Abstract: This paper proposes luteolin (LUT) as a novel depressant for the flotation-based separation of scheelite and calcite in a sodium oleate system. The suitability of LUT as a calcite depressant is confirmed through micro-flotation testing. At a pH of 9, with LUT concentration at 50 mg/L and sodium oleate concentration at 50 mg/L, scheelite recovery reaches 80.3%. Calcite, on the other hand, exhibits a recovery rate of 17.6%, indicating a significant difference in floatability between the two minerals. Subsequently, the surface modifications of scheelite and calcite following LUT treatment are characterized using adsorption capacity testing, Zeta potential analysis, Fourier transform infrared spectroscopy (FTIR), X-ray photoelectron spectroscopy (XPS), and atomic force microscopy (AFM). The study investigates the selective depressant mechanism of LUT on calcite. Adsorption capacity testing and Zeta potential analysis demonstrate substantial absorption of LUT on the surface of calcite, thereby impeding the further adsorption of sodium oleate, while its impact on scheelite is minimal. FTIR and XPS analyses reveal the selective adsorption of LUT onto the surface of calcite, forming strong chemisorption bonds between the hydroxyl group and calcium ions present. AFM directly illustrates the distinct adsorption densities of LUT on the two mineral types. Consequently, luteolin can effectively serve as a depressant for calcite, enabling the successful separation of scheelite and calcite.

We proposed a strategy of indirectly inducing uniform microarc discharge by controlling the content and distribution of β-Mg₁₇Al₁₂ phase in AZ91D Mg alloy. Two kinds of nano-particles (ZrO₂ or TiO₂) were designed to be added into the substrate of Mg alloy by friction stir processing (FSP). Then, Mg alloy sample designed with different precipitated morphology of β-Mg₁₇Al₁₂ phase was treated by microarc oxidation (MAO) in Na₃PO₄/Na₂SiO₃ electrolyte. The characteristics and performance of the MAO coating was analyzed using scanning electron microscopy, energy dispersive spectrometer, X-ray diffraction, X-ray photoelectron spectroscopy, contact angle meter, and potentiodynamic polarization. It was found that the coarse α-Mg grains in extruded AZ91D Mg alloy were refined by FSP, and the β-Mg₁₇Al₁₂ phase with reticular structure was broken and dispersed. The nano-ZrO₂ particles were pinned at the grain boundary by FSP, which refined the α-Mg grain and promoted the precipitation of β-Mg₁₇Al₁₂ phase in grains. It effectively inhibited the “cascade” phenomenon of microarcs, which induced the uniform distribution of discharge pores. The MAO coating on Zr-FSP sample had good wettability and corrosion resistance. However, TiO₂ particles was hardly detected in the coating on Ti-FSP sample.

Electrochemical lithium extraction from salt lake is an effective strategy for obtaining lithium resources with low cost. Nevertheless, the elevated magnesium (Mg) to lithium (Li) ratio in salt lake brines, along with the presence of numerous coexisting ions, gives rise to challenges such as prolonged lithium extraction periods, diminished lithium extraction efficiency, and significant environmental pollution. In this work, Lithium iron phosphate (LiFePO₄) serves as the electrode material for electrochemical lithium extraction. By adjusting the type of conductive agent, optimization of the conductive network for the LiFePO₄ electrode is achieved, resulting in a high lithium extraction efficiency and extended cycle life. Replacing the single conductive agent of Acetylene black (AB) or Multi-walled carbon nanotubes (MWCNTs) by the mixture conductive agent of AB/MWCNTs, the average diffusion coefficient of Li⁺ in the electrode increased from 2.35×10^-9 cm² s^-1 to 4.21×10^-9 cm² s^-1. Under the current density of 20 mA g^-1, the average capacity of lithium extraction increased from 30.36 mg (Li)/g (LiFePO₄) of the single conductive electrode to 35.62 mg (Li)/g (LiFePO₄), and the efficiency of lithium extraction was significantly improved. Using the mixed conductive agent, the capacity retention of the electrode after 30 cycles reaches 83.0%, which is much higher than that of the single conductive electrode of 65.8%, meanwhile the mixed conductive agent of AB/MWCNTs shows a better cycling performance. Reducing the content of conductive agent or increasing the loading capacity, the mixed conductive agent electrode still shows an excellent electrochemical performance. Furthermore, a self-designed, highly efficient, continuous lithium extraction device is constructed, in which the electrode utilizing the AB/MWCNTs mixed conductive agent maintains excellent adsorption capacity and cycling performance.  This work provides a new perspective for electrochemical extraction of lithium using LiFePO₄ electrode.

The synthesis of carbide coatings on graphite substrates using molten salt synthesis (MSS), has garnered significant interest due to its cost-effective nature. This study investigates the reaction process and growth kinetics involved in MSS, shedding light on key aspects of the process. The involvement of Ti powder through liquid-phase mass transfer is revealed, where the diffusion distance and quantity of Ti powder play a crucial role in determining the reaction rate by influencing the C concentration gradient on both sides of the carbide. Furthermore, the growth kinetics of the carbide coating are predominantly governed by the diffusion behavior of C within the carbide layer, rather than the chemical reaction rate. To analyze the kinetics, the thickness of the carbide layer is measured with respect to heat treatment time and temperature, unveiling a parabolic relationship within the temperature range of 700~1300℃. The estimated activation energy for the reaction is determined to be 179, 283 J mol⁻¹. These findings offer valuable insights into the synthesis of carbide coatings via MSS, facilitating their optimization and enhancing our understanding of their growth mechanisms and properties for various applications.

Porous intermetallics show potential in the field of filtration and separation as well as in the field of catalysis. Herein, porous TiFe₂ intermetallics were fabricated by the reactive synthesis of elemental powders. The phase transformation and pore formation of porous TiFe₂ intermetallics were investigated, and its corrosion behavior and hydrogen evolution reaction (HER) performance in alkali solution were studied. Porous TiFe₂ intermetallics with porosity in the range of 34.4% - 56.4% were synthesized by the diffusion reaction of Ti and Fe elements, and the pore formation of porous TiFe₂ intermetallic compound is the result of a combination of the bridging effect and the Kirkendall effect. The porous TiFe₂ samples exhibit better corrosion resistance compared with porous 316L stainless steel, which is related to the formation of uniform nanosheets on the surface that hinder further corrosion, and porous TiFe₂ electrode shows the overpotential of 220.6 and 295.6 mV at 10 and 100 mA cm^-2, suggesting a good catalytic performance. The synthesized porous Fe-based intermetallic has a controllable pore structure as well as excellent corrosion resistance, showing its potential in the field of filtration and separation.

Multi-material Laser-based Powder Bed Fusion (PBF-LB) allows manufacturing of parts with 3-dimensional gradient and additional functionality in a single step. This research focuses on the combination of thermally-conductive CuCr1Zr with hard M300 tool steel. Two interface configurations were investigated, i.e. M300 on CuCr1Zr and CuCr1Zr on M300. Ultra-fine grains form at the interface due to the low mutual solubility of Cu and steel. The material mixing zone size is dependent on the configurations and tunable in the range of 0.1–0.3 mm by introducing a separate set of parameters for the interface layers. Microcracks and pores mainly occur in the transition zone. Regardless of these defects, the thermal diffusivity of bimetallic parts with 50 vol.% of CuCr1Zr significantly increases by 70–150% compared to a pure M300 part. The thermal diffusivity of CuCr1Zr and the hardness of M300 steel can be enhanced simultaneously by applying the aging heat treatment.

CsPbX₃-based (X = I, Br, Cl) inorganic perovskite solar cells (PSCs) prepared by low-temperature process have attracted much attention because of their low cost and excellent thermal stability. But the high trap state density and serious charge recombination between low-temperature processed TiO₂ film and inorganic perovskite layer interface seriously restrict the performance of all-inorganic PSCs. Here a thin polyethylene oxide (PEO) layer is employed to modify TiO₂ film to passivate traps and promote carrier collection. The impacts of PEO layer on microstructure and photoelectric characteristics of TiO₂ film and related devices are systematically studied. Characterization results suggest that PEO modification can reduce the surface roughness of TiO₂ film, decrease its average surface potential and passivate trap states. At optimal conditions, the champion efficiency of CsPbI₂Br PSCs with PEO-modified TiO₂ (PEO-PSCs) has been improved to 11.24% from 9.03% of reference PSCs. Moreover, the hysteresis behavior and charge recombination have been suppressed in PEO-PSCs.

Water-quenched copper-nickel metallurgical slag, enriched with olivine minerals, exhibits promising potential for the production of CO₂ mineralization cementitious materials. In this work, we synthesized copper-nickel slag-based cementitious material (CNCM) by using different chemical activation methods to enhance its hydration reactivity and CO₂ mineralization capacity. Different water curing ages and carbonation conditions are explored with the examination of the mechanical properties and microstructure development of carbonated CNCM blocks. Meanwhile, thermogravimetry-differential scanning calorimetry and X-ray diffraction methods are used to evaluate the CO₂ adsorption amount and carbonation products of CNCM. Results show that the 3 d water-cured CNCM exhibited the highest CO₂ sequestration amount of 8.51 wt.% at 80 ℃ and 72 h while achieving a compressive strength of 39.07 MPa among the studied samples. This means that one ton of this CNCM can sequester 85.1 kg of CO₂ as well with high compressive strength. The addition of citric acid does not improve the strength development but is beneficial to increase the CO₂ diffusion and adsorption amount at the same carbonation condition. This work provided a possible solution for This work could be guidance for synthesizing CO₂ mineralization cementitious materials with large usage of metallurgical slags containing olivine minerals.

Solid-state impedance spectroscopy is used to investigate the influence of structural modifications resulting from the addition of Nb₂O₅ on the dielectric properties and relaxation processes in the quaternary mixed glass former (MGF) system 35Na₂O–10V₂O₅-(55–x)P₂O₅-xNb₂O₅ (x = 0–40 mol%). The dielectric parameters, including the dielectric strength, and dielectric loss, are determined from the frequency and temperature-dependent complex permittivity data, revealing a significant dependence on the Nb₂O₅ content. The transition from a predominantly phosphate glass network (x < 10, Region I) to a mixed niobate-phosphate glass network (10 ≤ x ≤ 20, Region II) leads to an increase in the dielectric parameters, which correlates with the observed trend in DC conductivity. In the predominantly niobate network (x ≥ 25, Region III), the highly polarizable nature of Nb⁵⁺ ions leads to a further increase in the dielectric permittivity and dielectric strength. This is particularly evident in Nb-40 glass-ceramic, which contains Na₁₃Nb₃₅O₉₄ crystalline phase with a tungsten bronze structure and exhibits the highest dielectric permittivity of 61.81 and the lowest loss factor of 0.032 at 303 K and 10 kHz. The relaxation studies, analyzed through modulus formalism and complex impedance data, show that DC conductivity and relaxation processes are governed by the same mechanism, attributed to ionic conductivity. In contrast to glasses with a single peak in M''(ω) due to DC conductivity, Nb-40 glass-ceramic exhibits two distinct contributions with similar relaxation times. The high-frequency peak indicates bulk ionic conductivity, while the additional low-frequency peak is associated with the grain boundary, confirmed by EEC modeling. The scaling characteristics of permittivity and conductivity spectra, along with the electrical modulus, validate time-temperature superposition and demonstrate a strong correlation with composition and modification of the glass structure upon Nb₂O₅ incorporation.

Heavy components of low-alloy high-strength (LAHS) steels are generally formed by multi-pass forging. It is necessary to explore the flow characteristics and hot workability of LAHS steels during the multi-pass forging process, which is beneficial to the formulation of actual processing parameters. In the study, the multi-pass hot compression experiments of a typical LAHS steel are carried out at a wide range of deformation temperatures and strain rates. It is found that the work hardening rate of the experimental material depends on deformation parameters and deformation passes. It is ascribed to the impacts of static and dynamic softening behaviors. A new model is established to describe the flow characteristics at various deformation passes. Compared to the classical Arrhenius model and modified ZA model, the newly proposed model shows higher prediction accuracy with a confidence level of 0.98565. Furthermore, the connection between power dissipation efficiency (PDE) and deformation parameters is revealed by analyzing the microstructures. The PDE cannot be utilized to reflect the efficiency of energy dissipation for microstructure evolution during the entire deformation process, but only to assess the efficiency of energy dissipation for microstructure evolution in a specific deformation parameter state. As a result, an integrated processing map is proposed to better study the hot workability of the LAHS steel, which considers the effects of instability factor (IF), PDE, and distribution and size of grains. The optimized processing parameters for the multi-pass deformation process are the deformation parameters of 1223~1318 K and 0.01~0.08 s^-1. Complete dynamic recrystallization occurs within the optimized processing parameters with an average grain size of 18.36~42.3 μm. It will guide the optimization of the forging process of heavy components.

To increase the proportion of fluxed pellets in the blast furnace burden is a useful way to reduce the carbon emissions in the ironmaking process. In this study, the interaction between calcium carbonate and iron ore powder and the mineralization mechanism of fluxed iron ore pellet in the roasting process were investigated through diffusion couple experiments. Scanning electron microscopy with energy dispersive spectroscopy was used to study the elements' diffusion and phase transformation during the roasting process. The results indicated that limestone decomposed into calcium oxide, and magnetite was oxidized to hematite at the early stage of preheating. With the increase in roasting temperature, the diffusion rate of Fe and Ca was obviously accelerated, while the diffusion rate of Si was relatively slow. The order of magnitude of interdiffusion coefficient of Fe₂O₃-CaO diffusion couple was 10⁻¹⁰ m²·s⁻¹ at a roasting temperature of 1473 K for 9 h. Ca₂Fe₂O₅ was the initial product in the Fe₂O₃-CaO-SiO₂ diffusion interface, and then Ca₂Fe₂O₅ continued to react with Fe₂O₃ to form CaFe₂O₄. With the expansion of the diffusion region, the SFC liquid phase was produced due to the melting of SiO₂ into CaFe₂O₄, which could strengthen the consolidation of fluxed pellets. Furthermore, andradite would be formed around a small part of quartz particles, which was also conducive to the consolidation of fluxed pellets. In addition, the principle diagram of limestone and quartz diffusion reaction in the process of fluxed pellet roasting was discussed.

Traditional hydrometallurgical methods for recovering spent lithium-ion batteries involve acid leaching to simultaneously extract all valuable metals into the leachate. This is followed by a series of separation steps such as precipitation, extraction, and stripping to separate the individual valuable metals. These processes are time-consuming and result in high lithium loss rates due to its late recovery stage. In this study, we present a process for selectively leaching lithium through the synergistic effect of sulfuric and oxalic acids. Under optimal leaching conditions (leaching time of 1.5 h, leaching temperature of 70 °C, liquid-solid ratio of 4 mL/g, sulfuric acid: oxalic acid = 1.3:1.3), the lithium leaching efficiency reached 89.6%, with good selectivity. XRD and ICP-OES analyses showed that most of the Ni, Co, and Mn in the raw material remained as oxides and oxalates in the residue. This study offers a new approach to enriching the relevant theory for the selective preferential leaching process of lithium.

With the application of resins in various fields, a large number of waste resins that are difficult to treat have been produced. The wastewater containing chromium produced by industry has seriously polluted the soil and groundwater environment, thus endangering human health. Therefore, in this paper, a novel functionalized mesoporous adsorbent PPR-Z for adsorption Cr(VI), was prepared from waste amidoxime resin. The waste amidoxime resin was firstly modified with H₃PO₄ and ZnCl₂, and subsequently was carbonized by slow thermal decomposition. The static adsorption of PPR-Z conforms to the pseudo second order kinetic model and Langmuir isotherm, which verifies that the adsorption of Cr(VI) by PPR-Z is mainly chemical adsorption and belongs to single-layer adsorption. The saturated adsorption capacity of the adsorbent for Cr(VI) can reach 255.86 mg/g. The adsorbent could effectively reduce Cr(VI) to Cr(III) and reduce the toxicity of Cr(VI) during adsorption. PPR-Z exhibited selectivity for Cr(VI) in electroplating wastewater. The main adsorption mechanisms includes chemical reduction of Cr(VI) into Cr(III), electrostatic interaction and coordination interaction. Preparation of PPR-Z not only solves the problem of waste resin treatment, but also effectively controls the pollution of chromium, and realizing the concept of "treating waste with waste".

The proper recycling of spent lithium-ion batteries (LIBs) can promote the recovery and utilization of valuable resources, while also negative environmental effects resulting from the presence of toxic and hazardous substances. In this study, a new environmentally friendly hydro-metallurgical process was proposed for leaching lithium (Li), nickel (Ni), cobalt (Co), and manganese (Mn) from spent LIBs using sulfuric acid with citric acid as a reductant. The effects of the concentration of sulfuric acid, the leaching temperature, the leaching time, the solid-liquid ratio, and the reducing agent dosages on the leaching behavior of the above elements were investigated. Key parameters were optimized using response surface methodology (RSM) to maximize the recovery of metals from spent LIBs. The maximum recovery efficiencies of Li, Ni, Co, and Mn can reach 99.08%, 97.99%, 98.76%, and 97.65% under the optimized conditions (the sulfuric acid concentration was 1.16 mol/L, the citric acid dosage was 15wt%, the solid-liquid ratio was 40 g/L, and the temperature was 83°C for 120 min), respectively.  It was found that in the collaborative leaching process of sulfuric acid and citric acid, the citric acid initially provided strong reducing  CO₂^·-  and the transition metal ions in the high state underwent a reduction reaction to produce transition metal ions in the low state. Additionally, citric acid can act as a proton donor and chelate with lower-priced transition metal ions, thus speeding up the dissolution process.

Although the commercialized poly (3,4-ethylenedioxythiophene):poly (styrenesulfonate) (PEDOT:PSS) is usually used as hole transport layer (HTL) in tin-based perovskite solar cells (TPSCs), its acidity damage the stability of TPSCs and restrict its further development. The PEDOT:PSS solution can be diluted by water to decrease acidity and reduce the cost of device fabrication, but the electrical conductivity will decrease obviously in diluted PEDOT:PSS. Herein, potassium thiocyanate (KSCN) is selected to regulate the properties of PEDOT:PSS HTL from the diluted PEDOT:PSS aqueous solution by water with a volume ratio of 1:1 to prepare efficient TPSCs. The concentrations of KSCN additive have been optimized. The effects of KSCN addition on the structure and photoelectrical properties of PEDOT:PSS HTL and TPSCs have been systematically studied. At the optimal KSCN concentration, the TPSCs based on KSCN-doped PEDOT:PSS HTL (KSCN-PSCs) demonstrate a champion power conversion efficiency (PCE) of 8.39%, while the reference TPSCs only show a champioan PCE of 6.70%. A series of characterization demonstrate that the KSCN additive increases the electrical conductivity of HTL prepared by the diluted PEDOT:PSS solution, improves the microstructure of perovskite film and inhibit carrier recombination in TPSCs, leading to the reduced hysteresis effect and enhanced PCE in KSCN-PSCs. This work gives a low-cost and practical strategy to develop a high-quality PEDOT:PSS HTL from diluted PEDOT:PSS aqueous solution for efficient TPSCs.

Co-Ni-based superalloys possess the capability to function at elevated temperatures and exhibit superior hot corrosion and thermal fatigue resistance. Therefore, they are expected to serve as crucial high-temperature structural materials for aero-engine and gas turbine hot-end components. In our previous work, we elucidated the influence of Ti and Ta on the high-temperature mechanical properties of the alloys. However, the intricate interplay among the elements also significantly affects the oxidation resistance of the alloys. In this paper, Co-35Ni-10Al-2W-5Cr-2Mo-1Nb-xTi-(5-x)Ta alloys (x = 1, 2, 3, 4) with varying Ti and Ta contents were designed and synthesized, and their oxidation resistance was studied from 800°C to 1000°C. After oxidation at three test conditions, 800°C for 200 h, 900°C for 200 h and 1000°C for 50 h, the main structure of the oxide layer of the alloy is spinel, Cr₂O₃ and Al₂O₃ in order from outside to inside. The oxides formed by Ta, W, and Mo are produced below the Cr₂O₃ layer. The findings reveal that the interaction of Ti and Ta elements imparts the highest oxidation resistance to the 3Ti2Ta alloy. Conversely, an excessive amount of Ti or Ta has an adverse effect on the oxidation resistance of the alloy. This study firstly reports the volatilization of W and Mo oxides during the oxidation process of Co-Ni-based cast superalloy with a high Al content and explains the formation mechanism of holes in the oxide layer. These results provide a basis for understanding the effect of the interaction of alloying elements on the oxidation resistance of the alloy.

The machine learning models of multiple linear regression (MLR), support vector regression (SVR), extreme learning machine (ELM), the proposed ELM model of online sequential ELM (OS-ELM) and OS-ELM with forgetting mechanism (FOS-ELM) are applied in predicting the lime utilization ratio of dephosphorization in BOF steelmaking process. Among the three basic models of MLR, SVR and ELM, ELM performs the best. OS-ELM and FOS-ELM are applied for the sequential learning and model updating. The optimal number of samples in validity term of the FOS-ELM model is determined to be 1500 with the smallest population MARE value of 0.058226. According to the variable importance analysis, the lime weight, initial P content and hot metal weight are the three most important variables for the lime utilization ratio. The lime utilization ratio will increase with the decrease of lime weight and the increases of initial P content and hot metal weight. A prediction system based on FOS-ELM is applied in the actual industrial production for one month. The hit ratios of the predicted lime utilization ratio in the error ranges of ±1%, ±3% and ±5% are 61.16%, 90.63% and 94.11%, respectively. The values of R², MARE and RMSE are 0.8670, 0.06823 and 1.4265, respectively. The performance of the system is pretty good for the application in the actual industrial production.

Iron-rich electrolytic manganese residue (IREMR) is the industrial waste residue produced during the processing of electrolytic metal manganese, which contains amounts of Fe, Mn resources and other heavy metals. In this study, to recover high-purity Fe powder from IREMR, slurry electrolysis technique was used. The effects of the IREMR and H₂SO₄ mass ratio, current density, reaction temperature and electrolytic time on the leaching efficiency and current efficiency of Fe were studied. The results indicated that high-purity Fe powder can be recovered from the cathode plate and that the slurry electrolyte can be recycled. The leaching efficiency, current efficiency and the purity of Fe were 92.43%, 80.65% and 98.72%, respectively, when the mass ratio of H₂SO₄ and IREMR was 1:2.5, the reaction temperature was 60℃, the electric current density was 30 mA/cm², and the reaction time was 8 h. In addition, the VSM analysis showed that the coercivity of electrolytic iron powder was 54.5 A/m, which reached the electrical pure iron powder coercivity advanced magnetic grade (DT4A coercivity standard). The slurry electrolytic method provides fundamental support for the industrial application of Fe resource recovery in IRMER.

A new process for the efficient recovery of molybdenum from molybdenum concentrate by microwave roasting and sodium hydroxide leaching was proposed, as an environmentally benign and economical alternative. Thermodynamic analysis indicated the feasibility of oxidative roasting of molybdenum concentrates. The effects of roasting temperature, holding time and power to mass ratio on the oxidation and leaching process on the formation of sodium molybdate (Na₂MoO₄-2H₂O) were investigated. The optimal process conditions for oxidation roasting were found to be a roasting temperature of 700°C, a holding time of 110 min and a power to mass ratio of 110 W/g, while for leaching the optimal conditions correspond to sodium hydroxide concentration of 2.5 mol/L, a liquid to solid ratio of 2:1, a leaching temperature of 60°C and the leaching solution was terminated at pH 8. The optimum conditions result in the leaching rate of 96.24% for sodium molybdate with 94.08% content. A variety advanced characterization techniques such as XRF, XRD, SEM-EDS and FTIR were utilized to elucidate the conversion process.v

With a growing depletion of high-grade iron ores, the increased aluminum content in the iron ore concentrates is unavoidable, which is detrimental to the pelletizing process. Therefore, it is essential to discover the effect mechanism of aluminum on pellet quality. In this paper, the effect of aluminum occurrence and content on the induration of both hematite and magnetite pellets was investigated by adding corresponding Al-containing additives including alumina, alumogoethite, gibbsite and kaolinite. The related mechanism was also revealed through not only systematic process mineralogy analyses combined with the thermodynamic properties of different aluminum occurrence, but also the quantitative characterization of consolidation behaviors. The results show that the alumina from different aluminum occurrence had an adverse effect on the induration characteristics of pellets, especially when the aluminum content was more than 2.0wt%. The thermal decomposition of gibbsite and kaolinite will tend to generate internal stress and fine cracks, which go against the respective formation of microcrystalline bonding and recrystallization between the Fe₂O₃ particles. The adverse effect on the induration characteristics of fired pellets with different aluminum occurrence can be relieved to varying degrees through the formation of slag bonds of CaO-Fe₂O₃-Al₂O₃-SiO₂ polybasic eutectoid between the hematite particles. The kaolinite is more beneficial to the induration process than other three aluminum occurrence because of formation of more liquid phase which improves the consolidation of pellets. The research results can help to further understand the effect of aluminum occurrence and content in iron ore concentrates on downstream processing, and then provide a good guidance for the utilization of high-alumina iron ore concentrates in pelletizing.

The paper proposes a biomass cross-upgrading process that combines hydrothermal carbonization and pyrolysis to produce high-quality blast furnace injection fuel. The results demonstrate significant reductions in the volatile content of biochar, from 45.35% to 16.19%, as well as decreases in alkali metal content, ash content, and specific surface area. The optimal route for biochar production is hydrothermal carbonization-pyrolysis, resulting in biochar (P-HC) with a higher calorific value, C=C structure, and increased graphitization degree. The apparent activation energy (E) of the sample ranges from 199.1 kJ/mol to 324.8 kJ/mol, with P-HC having an E of 277.8 kJ/mol, lower than that of raw biomass, primary biochar, and anthracite. This makes P-HC more suitable for blast furnace injection fuel. Additionally, the paper proposes a path for P-HC injection in blast furnaces and calculates potential environmental benefits. P-HC offers the highest potential for carbon emission reduction, capable of reducing emissions by 96.04 kg/tHM when replacing 40% coal injection.

Direct reduction process based on the hydrogen metallurgy gas-based shaft furnace is a promising technology for efficiently and low-carbon smelt vanadium-titanium magnetite (VTM). However, in the direct reduction process, sticking of pellets occurs due to the aggregation of metallic iron between the contact surfaces of adjacent pellets, which will have a serious negative effect on the continuous operation. This paper presents a detailed experimental study of the effect of TiO₂ on the sticking behavior of pellets during direct reduction process under different reduction conditions. The results showed that sticking index (SI) decreased linearly with increasing TiO₂ addition, which stemmed from the increase of unreduced FeTiO₃ during reduction, leading to decrease of the number and strength of metallic iron interconnections at the sticking interface. When the TiO₂ addition was raised from 0% to 15% at 1100°C, SI increased from 0.71% to 59.91%. The connection of slag phase could be attributed to the sticking at low reduction temperature corresponding to low sticking strength. Moreover, interconnection of metallic iron became the dominant factor as reduction temperature increased, and SI increased sharply. Additionally, TiO₂ had a great effect on SI at high reduction temperature compared to low reduction temperature.

The development of anode materials with high rate capability and long charge-discharge plateau is the key to improve performance of lithium-ion capacitors (LICs). Herein, the porous graphitic carbon (PGC-1300) derived from a new triplyinterpenetrated cobalt metal-organic framework (Co-MOF) is prepared through the facile and robust carbonization at 1300 ^oC and washing by HCl solution. The as-prepared PGC-1300 features an optimized graphitization degree and porous framework, which not only contributes to high plateau capacity (105 mAh g^-1 below 0.2 V at 0.05 A g^-1), but also supplies more convenient pathways for ions and increases the rate capability (128.5 mAh g^-1 at 3.2 A g^-1). According to the kinetics analyses, it can be found that diffusion regulated surface induced capacitive process and Li-ions intercalation process are coexisted for lithium ion storage. Additionally, LIC PGC-1300//AC constructed with pre-lithiated PGC-1300 anode and activated carbon (AC) cathode exhibits an increased energy density of 102.8 Wh kg^-1, a power density of 6017.1 W kg^-1, together with the excellent cyclic stability (91.6% retention after 10000 cycles at 1 A g^-1).

Cation additive can efficiently enhance the total electrochemical capabilities of zinc ion hybrid capacitors (ZHCs). However, their energy storing mechanisms are still under debated in zinc-based systems. Herein, we assemble several Zn // AC devices with different concentration electrolytes and investigate their electrochemical reaction dynamic behaviors. The zinc ion capacitor with Mg²⁺ mixed solution provides 82 mAh g^-1 capacity at 1A g^-1 and maintains 91% of original capacitance after 10,000 cycling. It is superior to the other assembled zinc ion devices in single component electrolyte. It demonstrates that the double ion storage mechanism enables superior rate performance and long cycle lifetime in ZHCs.

The separated preparation of pre-alloys and amorphous alloys leads to severe solidification-remelting and beneficial elements removal-readdition contradictions, which greatly increases the energy consumption and emissions. In this study, a novel strategy for the direct production of FePC amorphous soft magnetic alloys via smelting reduction of high-phosphorus iron ore (HPIO) and apatite was proposed. The thermodynamic conditions and equilibriums of the carbothermal reduction reactions in HPIO were first calculated and the elements content in reduced alloys were theoretically determined. Experimentally, the phase and structure evolutions as well as the elements migration and enrichment behaviors during the smelting reduction of HPIO and Ca₃(PO₄)₂ were then verified. The addition of Ca₃(PO₄)₂ in HPIO contributes to the enrichment of P element in reduced alloys and the successive appearance of Fe₃P, Fe₂P phases. The content of P, C elements in the range of 1.52-14.63wt% and 0.62-2.47wt% can be well tailored by adding 0-50 g Ca₃(PO₄)₂ and controlling the C/O ratio of 0.8-1.1, which is quite consistent with the calculated results. These resultant FePC alloys were then successfully prepared into amorphous ribbons and rods. Compared with the conventional production process, the energy consumption of our proposed strategy was estimated to be 680 kgce/t, which can be reduced by 30%. These results are quite vital for the comprehensive utilization of mineral resources and pave the way for the cleaner production of Fe-based amorphous soft magnetic alloys.

The activation of alkyl dimethyl betaine (ADB) on the collection capacity of sodium oleate (NaOL) at low temperatures was evaluated using flotation tests at different scales. The synergistic mechanism of ADB and NaOL under low temperatures was also explored by infrared spectroscopy, X-ray photoelectron spectroscopy, surface tension measurement, foam performance test and flotation reagent size measurement. Based on the results of flotation tests, the collector mixed with octadecyl dimethyl betaine (ODB) and NaOL in a mass ratio of 4:96 revealed the most outstanding collection capacity. Under a low temperature of 8 °C–12 ℃, the combined collector could increase the scheelite recovery by 3.48% in the Luanchuan area, which has the largest scheelite concentrate output in China. The mechanism research results confirmed that ODB optimised the collection capability of NaOL by improving the dispersion and foaming performance. Betaine can be introduced as an additive of NaOL to improve the recovery of scheelite at low temperatures.

Aluminum (Al) is considered as a promising lithium-ion battery (LIB) anode material owing to its high theoretical capacity and appropriate lithation-delithation potential. Unluckily, its inevitable volume expansion causes the electrode structure instability, leading to poor cyclic stability. What’s worse, the natural Al₂O₃ layer on commercial Al pellets is always existed as a robust insulating barrier for electrons, which brings the voltage dip and results in low reversible capacity. Herein, we synthesized core-shell Al@C-Sn pellets for LIBs by a plus-minus strategy. In this proposal, the natural Al₂O₃ passivation layer is eliminated when annealing the pre-introduced SnCl₂, meanwhile, polydopamine-derived carbon is introduced as dual functional shell to alleviate the volume swellings and liberate the fresh Al core from re-oxidization. Benefiting from the addition of C-Sn shell and the elimination of the Al₂O₃ passivation layer, the as-prepared Al@C-Sn pellet electrode exhibits little voltage dip and delivers a reversible capacity of 1018.7 mAh g⁻¹ at 0.1 A g^-1 and 295.0 mAh g^-1 at 2.0 A g^-1 (after 1000 cycles). Moreover, its diffusion-controlled capacity is muchly improved compared to those of its counterparts, confirming the well-designed nanostructure contributes to the rapid Li-ion diffusion and further enhances the lithium storage activity.

X-ray excited photodynamic therapy (X-PDT), is the bravo answer of photodynamic therapy (PDT) for deep-seated tumors, as it employs X-ray as the irradiation source to overcome the limitation of light penetration depth. However, high X-ray irradiation dose caused organ lesions and side effects became the major barrier to X-PDT application. To address this issue, firstly, we employed a classical co-precipitation reaction to synthesize NaLuF₄: 15%Tb³⁺(NLF) with an average particle size of 23.48 ± 0.91 nm, which was then coupled with the photosensitizer merocyanine 540 (MC540) to form the X-PDT system NLF-MC540 with high production of singlet oxygen. Secondly, the system could induce antitumor efficacy to about 24% in relative low dose X-ray irradiation range (0.1-0.3 Gy). In vivo, when NLF-MC540 irradiated by 0.1 Gy X-ray, the tumor inhibition percentage reached 89.5 ± 5.7%. Finally, we try to find the therapeutic mechanism which may exist in low dose X-PDT. A significant increase of neutrophils in serum was found on the third day after X-PDT. By immunohistochemical staining of tumor sections, we studied the Ly6G⁺, CD8⁺, and CD11c⁺ cells infiltrated in the tumor microenvironment. Utilizing the bilateral tumor model, we found the NLF-MC540 with 0.1 Gy X-ray irradiation could inhibit both the primary tumor and the distant tumor growth. Detected by Elisa assay, two cytokines IFN-γ and TNF-α in serum were upregulated 7 times and 6 times than negative control. Detected by Elispot assay, the number of immune cells attributable to the IFN-γ and TNF-α levels in the group of low dose X-PDT were 14 times and 6 times greater than that in the negative control group. Thus, we could conclude that our low dose X-PDT system could successfully upregulate the levels of immune cells, stimulate the secretion of cytokines (especially IFN-γ and TNF-α), activate antitumor immunity, finally inhibit colon tumor growth.

High chromium vanadium-titanium magnetite (HVTM) is a crucial polymetallic-associated resource to be developed. All pellets operation is one of the trends of blast furnaces to reduce CO₂ emission in the future. By referencing the production data of vanadium-titanium magnetite blast furnaces, this study explored the softening-melting (S-M) behavior of high chromium vanadium-titanium magnetite and obtained the optimal integrated burden based on flux pellets. The results showed that the burden composition of 70% flux pellets and 30% acid pellets obtained best S-M properties. In comparison with single burden, the S-M characteristic temperature of this burden composition was higher, the cohesive zone shifted downward and narrowed from 307 °C to 282 °C, the maximum pressure drop (ΔP_max) decreased from 26.76 kPa to 19.01 kPa, and the Permeability index (S) dropped from 4643.5 kPa·°C to 2446.8 kPa·°C. The S-M properties of integrated burden improved apparently. During the softening process, the acid pellets played a role in withstanding the load, and the flux pellets in the integrated burden during the melting process exhibited a higher slag melting point, which increased the melting temperature. The homogeneity of the slag and the TiC produced by the over-reduction led to the deterioration of the gas permeability of single burden. The segregation of acid and flux pellets in the HVTM proportion and basicity was the main reason for the better S-M properties of the integrated burden.

The pure cobalt (Co) thin films were fabricated by direct current magnetron sputtering, and the effects of sputtering power and pressure on the microstructure and electromagnetic properties were investigated. The results reveal that as the sputtering power increases from 15 W to 60 W, the Co thin film transitions from an amorphous to a polycrystalline state, which is accompanied by an increase in intercrystal pore width. Concurrently, resistivity decreases by 65%, coercivity escalates from 162 Oe to 292 Oe, and the in-plane magnetic anisotropy disappears as the film transitions to a polycrystalline state. As the sputtering pressure decreases from 1.6 Pa to 0.2 Pa, there is a notable increase in grain size, along with a dramatic drop in resistivity (from 377 μΩcm to 37 μΩcm) and a significant rise in coercivity (from 67 Oe to 280 Oe), which can be ascribed to the increasing defect width. Correspondingly, a quantitative model for the coercivity of Co thin films has been formulated. In the polycrystalline films sputtered under pressures of 0.2 Pa and 0.4 Pa, significant in-plane magnetic anisotropy is observed, which is primarily attributable to increased microstress.

The hot deformation behaviors of 316LN-Mn austenitic stainless steel (ASS) are investigated under uniaxial isothermal compression tests at different temperatures and strain rates. Additionally, the microstructural evolutions are investigated using electron backscatter diffraction (EBSD). The flow

stress decreased with increasing temperature and decreasing strain rate. A constitutive equation is established to characterize the relationship among the deformation parameters, and the deformation activation energy is calculated to be 497.92 kJ/mol. The processing maps are constructed to describe the

appropriate processing window, and the optimum processing parameters are determined at the temperature of 1107-1160 °C and the strain rate of 0.005-0.026 s ^-1 . The experimental results show that the main nucleation mechanism is discontinuous dynamic recrystallization (DDRX), and continuous dynamic recrystallization (CDRX) plays the secondary place. The formation of twin boundaries also facilitates the nucleation of dynamic recrystallization (DRX).

Chromium plays a vital role in stainless steel due to its ability to improve the corrosion resistance of the latter. However, the release of chromium from stainless steel slag (SSS) during SSS stockpiling causes detrimental environmental issues. To prevent chromium pollution, the effects of iron oxide on crystallization behavior and spatial distribution of spinel were investigated in this work. The results revealed that FeO was more conducive to the growth of spinels compared with Fe₂O₃ and Fe₃O₄. Spinels were found to be mainly distributed at the top and bottom of slag. The amount of spinel phase at the bottom decreased with the increasing FeO content, while that at the top increased. The average particle size of spinel in the slag with 18wt% FeO content was 12.8 µm. Meanwhile, no notable structural changes were observed with a further increase in FeO concentration. In other words, the spatial distribution of spinel changed when the content of iron oxide varied in the range of 8 to 18wt%. Finally, less spinel was found at the bottom of slag with a FeO concentration of 23wt%.

W-based WTaVCr refractory high entropy alloys (RHEA) may be novel and promising candidate materials for plasma facing components in the first wall and diverter in fusion reactors. This alloy has been developed by a powder metallurgy process combining mechanical alloying and spark plasma sintering (SPS). The SPSed samples contained two phases, in which the matrix is RHEA with a body-centered cubic structure, while the oxide phase was most likely Ta₂VO₆ and TaVO₄ through a combined analysis of X-ray diffraction (XRD), energy-dispersive spectroscopy (EDS), and selected area electron diffraction (SAED).  The higher oxygen affinity of Ta and V may explain the preferential formation of their oxide phase based on thermodynamic calculations. Electron backscatter diffraction (EBSD) revealed an average grain size of 6.2 μm. WTaVCr RHEA showed a peak compressive strength of 2997 MPa at room temperature and much higher micro- and nano-hardness than W and other W-based RHEAs in the literature. Their high Rockwell hardness can be retained to at least 1000 ºC.  

The variation characteristics of bubble morphology and the thermal-physical properties of bubble boundary in the top-blown smelting furnace are explored by means of the computational fluid dynamics method. The essential aspects of the fluid phase (e.g. splashing volume, dead zone of copper slag, and gas penetration depth) are explored, together with the effect of sinusoidal pulsating gas intake on the momentum transfer performance between phases. The results illustrate that two relatively larger vortices and two smaller vortices appear in the bubble waist and below the lance, respectively. The larger ones expand and the smaller ones shrink, leading to the contraction of the bubble waist. Compared to the constant velocity condition, the splashing volume and dead zone volume of the slag under the V_g=58+10sin(2πt) condition are reduced by 24.9% and 23.5%, respectively. Gas penetration depth and slag velocity of the latter are 1.03 and 1.31 times higher than those of the former, respectively.

The hot compression behavior of the as-extruded Mg-0.6Mn-0.5Al-0.5Zn-0.4Ca alloy was studied on a Gleeble-3500 thermal simulation machine. The experiments were conducted at temperatures ranging from 523 K to 673 K and strain rates ranging from 0.001 s^–1 to 1 s^–1, respectively. The results exhibited that an increase in strain rate or a decrease in deformation temperature will lead to an increase in true stress. The constitutive equation and processing maps have been obtained and analyzed. The influence of deformation temperatures and strain rates on microstructural evolution and texture were studied with the assistance of electron backscatter diffraction (EBSD). The as-extruded alloy showed a bimodal structure, consisting of deformed coarse grains and fine equiaxed recrystallization structure (about 1.57 μm). The EBSD results of deformed alloys revealed that both the recrystallization degree and the average grain size increase as the deformation temperature increases. In contrast, the dislocation density and the texture intensity decrease. The compressive texture becomes weak with the increase of deformation temperature at the strain rate of 0.01 s^-1. Most grains with {0001} planes tilt away from the compression direction gradually. In addition, when the strain rate decreases both the recrystallization degree and the average grain size increase. Meanwhile, the dislocation density decreases. The texture seems not to be sensitive to the strain rate.

Coagulation process is a core technology that has been widely applied in water and wastewater treatment. In this paper, novel composite coagulants poly-ferric-magnesium-silicate-sulfate (PFMS) were synthesized by using Na₂SiO₃·9H₂O, Fe₂(SO₄)₃ and MgSO₄ as the raw materials. The effects of aging time, Fe:Si:Mg and OH:M molar ratios (M represents the metal ions) on the coagulation performance of the as-prepared PFMS were systematically investigated to obtain optimum coagulants. The results showed that PFMS coagulant exhibited good coagulation properties in treating simulated humic acid-kaolin surface water and reactive dye wastewater. When the molar ratios were controlled at Fe:Si:Mg=2:2:1 and OH:M=0.32, the obtained PFMS presented excellent stability along with high coagulation efficiency (the removal efficiency of UV₂₅₄ was 99.81%, and the residual turbidity of the surface water was 0.56 NTU at a dosage of 30 mg/L). After standing the coagulant for 120 days in the laboratory, the removal efficiency of UV₂₅₄ and residual turbidity of the surface water still maintained 88.12% and 0.68 NTU, respectively, meeting the surface water treatment requirements. In addition, the coagulation performance in treating reactive dye wastewater was greatly improved by combining the advantages of magnesium and iron salts. Compared with poly-ferric-silicate-sulfate (PFS) and poly-magnesium-silicate-sulfate (PMS), PFMS coagulant played a good decolorization role within the pH range of 7-13.

It is meaningful to improve the impedance matching of the material while maintaining its excellent wave absorption properties. In this paper, according to the hydrolysis characteristics of isopropyl titanate (TTIP), a simple preparation process of carbonyl iron powder (CIP) coated with TiO₂ was designed. Due to the coated TiO₂, the impedance matching of the CIP@TiO₂ composite was well adjusted by decreasing the dielectric constant. Moreover, the interfacial polarization of CIP@TiO₂ has also been enhanced. Ultimately, the electromagnetic wave (EMW) absorption property of CIP@TiO₂ composite was significantly improved, the minimum reflection loss (RL_min) reach -46.07 dB, and the effective absorption bandwidth (EAB) can reach 8 GHz when the thickness is only 1.5 mm. Moreover, compared the CIP, the oxidation resistance of CIP@TiO₂ was significantly improved. The results shown that the oxidation starting temperature of CIP@TiO₂ is 400^oC, whereas uncoated CIP has an oxidation starting temperature of about 250^oC. Moreover, the largest oxidation rate temperature of CIP@TiO₂ was increased to about 550^oC. This work opens up a novel strategy for producing high-performance EMW absorbers with the help of structure design.

Flotation separation of magnesite and its calcium-containing carbonate minerals is a difficult problem. Recently, new regulators have been proposed for magnesite flotation decalcification, although traditional adjusters such as tannin, water glass, sodium carbonate and sodium hexametaphosphate are more widely used in industry. However, they are rarely used as the main regulators in research because they perform poorly in magnesite and dolomite single-mineral flotation tests. Inspired by the limonite pre-desilting method and the addition of a modifier to magnesite slurry mixing, we used a tannin pretreatment method for separating magnesite and dolomite. Microflotation experiments confirmed that the tannin pretreatment method selectively and largely reduces the flotation recovery rate of dolomite without affecting the flotation recovery rate of magnesite. Moreover, the contact angles of the tannin-pretreated magnesite and dolomite increased and decreased, respectively, in the presence of NaOL. Zeta potential and Fourier transform infrared analyses showed that the tannin pretreatment method efficiently hinders NaOL adsorption on the dolomite surface but does not affect NaOL adsorption on the magnesite surface. X-ray photoelectron spectroscopy and density functional theory calculations confirmed that tannin interacts more strongly with dolomite than with magnesite.

The multiple quantum transitions within d-band correlation oxides such as rare-earth nickelates (ReNiO₃) triggered by critical temperatures and/or hydrogenation opened up a new paradigm for correlated electronics applications, e.g., ocean electric field sensor, bio-sensor, and neuron synapse logical devices. Nevertheless, these applications are obstructed by the present ineffectiveness in the thin film growth of the metastable ReNiO₃ with flexibly adjustable rare-earth compositions and electronic structures. Herein, we demonstrate a metal-organic decompositions (MOD) approach that can effectively grow metastable ReNiO₃ covering a large variety of the rare-earth composition without introducing any vacuum process. Unlike the previous chemical growths for ReNiO₃ relying on strict interfacial coherency that limit the film thickness, the MOD growths using reactive isooctanoate percussors are tolerant to lattice defects and therefore achieves comparable film thickness to vacuum depositions. Further indicated by positron annihilation spectroscopy, the ReNiO₃ grown by MOD exhibit large amount of lattice defects that improves their hydrogen incorporation amount and electron transfers, as demonstrated by the resonant nuclear reaction analysis and near edge X-ray absorption fine structure analysis. This effectively enlarges the magnitude in the resistance regulations in particular for ReNiO₃ with lighter Re, shedding a light on the extrinsic regulation of the hydrogen induced quantum transitions for correlated oxides semiconductors kinetically via defect engineering.

In recent years, it has become widely acknowledged that the addition of nickel (Ni) can enhance the mechanical properties of Al-Si alloys. However, the impact of Ni on the wear behavior of Al-Si alloys and Al matrix composites, particularly at elevated temperatures, remains an understudied area. In this study, Al-Si-Cu-Mg-Ni/20wt% SiCp composites with varying Ni contents were prepared by a semi-solid stir casting method. The effect of Ni content on the dry sliding wear behavior of the prepared composites was investigated by sliding tests at 25℃ and 350℃. The results indicated that the θ-Al₂Cu phase gradually diminished and eventually disappeared as the Ni content increases from 0 to 3wt%, accompanied by the formation and increase of the δ-Al₃CuNi phase and ε-Al3Ni phase in the microstructure. The hardness and ultimate tensile strength of the as-cast composites are both improved, and the wear rates of the composites are decreased from 5.29 to 1.94 at 25℃ and 20.2 to 7 mm³/(N∙m) at 350℃ with a rise in Ni content from 0 to 2wt%. The enhanced performance is due to the strengthening network structures and the presence of more Ni-containing phases in the composites. However, the wear rate of the 3Ni composite is approximately 2 times higher than that of the 2Ni composite due to the fracture and debonding of the ε-Al₃Ni phase. The predominant wear mechanisms of the investigated composites are abrasive wear, delamination wear, and oxidation wear at 25℃, while delamination wear and oxidation wear are dominant during sliding at 350℃.

The challenge of high temperatures in deep mining has remained harmful to the health of workers and their production efficiency. Adding phase change materials to filling slurry and using the cold storage function of these phase change materials to reduce downhole temperatures was shown to be an effective approach to alleviate the aforementioned problem. Paraffin-CaCl₂·6H₂O composite phase change material was prepared in the laboratory. The composition, phase change latent heat, thermal conductivity, and cemented tailings backfill (CTB) compressive strength of the new material were studied. Its heat transfer characteristics and endothermic effect of the phase change material were simulated using Fluent software. The results showed the following: (1) The new paraffin-CaCl₂·6H₂O composite phase change material improved the thermal conductivity of the native paraffin while avoiding the disadvantageous water solubility of CaCl₂·6H₂O. (2) The calculation formula of the thermal conductivity of CaCl₂·6H₂O combined with paraffin was deduced，and the reasons were explained in principle. (3) The “enthalpy–mass scale model” was applied to calculate the latent heat of phase change of nonreactive composite phase change materials. (4) The addition of the composite phase change material Paraffin-CaCl₂·6H₂O reduces the CTB strength but increases its heat absorption capacity.

Lithium recovery from spent lithium-ion batteries (LIBs) becomes increasingly important due to the skyrocketing price of lithium. Medium-temperature carbon reduction roasting was reported in this work, which aimed at preferential selective extraction of lithium from spent LiCoO₂ (LCO) cathodes to overcome the incomplete recovery and loss of lithium during the recycling process. The LCO layered structure was destroyed and lithium was completely converted into water-soluble Li₂CO₃ under a suitable temperature to control the reduced state of the cobalt oxide. The Co metal agglomerates generated during medium-temperature carbon reduction roasting were broken by wet grinding and ultrasonic crushing to release the entrained lithium. The results showed that 99.10wt% of the whole lithium could be recovered as Li₂CO₃ with a purity of 99.55wt%. This study provided a new perspective on the preferentially selective extraction of lithium from spent lithium batteries.

Flotation separation of calcite from fluorite is a challenge on low grade fluorite flotation, which limits the recovery and purity of fluorite concentrate. This paper proposed a new acid leaching-flotation process for fluorite. This innovative process raised the fluorite's grade to 97.26% while producing nanoscale calcium carbonate from its leachate, which contained plenty of calcium ions. On the production of nanoscale calcium carbonate, the impacts of solid-liquid ratio, pH, temperature, and titration rate were examined. By modifying the process conditions and utilizing crystal conditioning agents, calcite-type calcium carbonate with a particle size of 1.823 μm and amorphous calcium carbonate with a particle size of 1.511 μm were produced. The influence of the impurity ions Mn²⁺, Mg²⁺, and Fe³⁺ was demonstrated to reduce the particle size of nanoscale calcium carbonate and make crystal shape easier to manage in the fluorite leach solution system when compared to calcium chloride solution. The combination of the acid leaching-flotation process and the nanoscale calcium carbonate preparation method improved the grade of fluorite while recovering calcite resources, presenting a novel idea for the effective and clean usage of low-quality fluorite resources with microfine particles embedded.

There is a rapid performance degradation in the initial aging process of solid oxide fuel cell (SOFC), and the discussion of degradation mechanism needs quantitative analysis. The Focused Ion Beam - Scanning Electron Microscopy (FIB-SEM) technique is used to characterize and reconstruct the ceramic microstructures of SOFC anodes. The lattice Boltzmann method (LBM) simulation is performed to simulate the multi-physical and electrochemical processes in the reconstructed models. Two samples taken from industrial size cells are processed, including a reduced reference cell, and a cell with an initial aging process. Statistical parameters of the reconstructed microstructure show a significant decrease in the active triple-phase boundary (TPB) and Ni connectivity in the aged cell compared to the reference cell. The LBM simulation reveals that the activity degradation is the dominant factor compared to the microstructure degradation during the initial aging process, and the electrochemical reactions spread to the support layer in the aged cell. The microstructure degradation and activity degradation can both be attributed to the Ni migration and coarsening.

The prediction and control of furnace heat indicator was of great significance to improve the furnace hot level and furnace condition for the complex and difficult to operate the hour-class delay blast furnace (BF) system. In this work, a prediction and feedback model of furnace heat indicator based on the fusion of data driven and BF ironmaking process was proposed. The data of raw and fuel materials, process operation, smelting state and slag and iron discharge during the whole BF process were comprehensively analyzed, a total of 171 variables, 9223 groups of data. A novel method of delay analysis of furnace heat indicator was established. and the extracted delay variables had played an important role in the modeling. Compared with the traditional machine learning algorithm, the method that combined the Genetic algorithm (GA) and Stacking was efficient to improve the performance. The hit rate for the predicting the temperature of hot metal in the error range of plus or minus 10 ℃ was 92.4%, and that for [Si] in the error range of plus or minus 0.1% was 93.3%. On the basis of the furnace heat prediction model and the expert experience, a feedback model of furnace heat operation was established to push the quantitative operation suggestions to stabilize the BF heat level, which had been highly recognized by the BF operators. Finally, this comprehensive and dynamic model had been successfully applied in the practical BF, and the BF temperature level was improved remarkably with the furnace temperature stability rate increasing from 54.88% to 84.89%, which had achieved significant economic benefits.

A Ni-P alloy gradient coating consisting of multiple electroless Ni-P layers with various phosphorus content was prepared on the aviation aluminum alloy. Several characterization and electrochemical techniques were used to characterize the different Ni-P coatings’ morphologies, phase structures, elemental compositions, and corrosion protection. The gradient coating showed good adhesion, and high corrosion and wear resistance, enabling the application of aluminum alloy in harsh environments. The results showed that the double zinc immersion was vital in obtaining excellent adhesion (81.2 N). The optimal coating was not peeled and shredded even after bending tests with angles higher than 90° and was not corroded visually after 500 h of neutral salt spray test at 35 ℃. The high corrosion resistance was attributed to the misaligning of these micro defects in the three different nickel alloy layers and the amorphous structure of the high P content in the outer layer. These findings guide the exploration of functional gradient coatings that meet the high application requirement of aluminum alloy parts in complicated and harsh aviation environments.

Higher thrust-to-weight ratio poses challenges for the high-temperature performance of Ni-based superalloys. The oxidation behavior of GH4738 at extreme temperature has been investigated by isothermal and non-isothermal experiments. Resulted from the competitive diffusion of alloying elements, the oxide scale includes the outermost porous oxide layer (OOL), the inner relatively dense oxide layer (IOL) and internal oxide zone (IOZ) depending on the temperature and time. Higher temperature leads to the formation of big voids at the IOL/IOZ interface. At 1200°C, the continuity of Cr-rich oxide layer in the IOL is destroyed and thus spallation occurs. Extending oxidation time contributes to the size of Al-rich oxide particles within the IOZ increase. Based on this, the oxidation kinetics of GH4738 is discussed and the corresponding oxidation behavior at 900-1100°C is predicted.

To achieve the rational utilization of low-grade co-associated complex manganese ore resources, this paper systematically elucidated the mechanism of the phase transformation process of roasting in a reducing atmosphere with pyrolusite ore (MnO₂) as the research object. According to the single-factor experiment results, the divalent manganese (Mn²⁺) reduction rate of the roasted product obtained as 95.30% at a roasting time of 25 min, a roasting temperature of 700°C, a CO concentration of 20at% and a total gas volume of 500 mL·min^-1, in which the manganese was mainly in the form of manganosite (MnO). Scanning electron microscopy (SEM) and Brunauer-Emmett-Teller (BET) demonstrated the microstructural evolution of the roasted products, and the reduction of pyrolusite ore was completed gradually from the surface to the core. Thermodynamic calculations, X-ray photoelectron spectroscopy(XPS), and X-ray diffractometry (XRD) elucidated that the phase transformation of pyrolusite follows MnO₂→Mn₂O₃→Mn₃O₄→MnO phase by phase and that the reduction of manganese oxides in each valence state proceeds simultaneously.

Conversion of agricultural residual biomass into biochar as sulfur host materials for Li-S batteries is a promising approach to alleviate green house effect and realize waste resource re-utilization. However, the low electrical conductivity and less electocatalytic sites of pristine biochar hinder its large-scale application. Herein, these challenges are addressed by constructing Fe-N co-doped biochar (Fe-NOPC) through co-pyrolysis of sesame shells and NaFeEDTA. During synthesis process, NaFeEDTA can be used as an extra carbon resource to regulate the chemical environment of N-doped, producing high content of graphitic, pyridinic, pyrrolic N, and Fe-N_x bonds. When the resulted Fe-NOPC is used as a sulfur host, the pyridinic and pyrrolic N can greatly adjust the surface electron structure of biochar for accelerating the electron/ion transport, while electropositive graphitic N can combine with sulfur-related species by electrostatic attraction. Moreover, the Fe-N_x is capable of promoting the redox reaction of LiPSs owing to the strong Li-N and S-Fe binding. Benefiting from these advantages, the resultant Fe-NOPC/S cathode with a sulfur loading of 3.8 mg cm^-2 delivers an areal capacity of 4.45 mAh cm^-2 under 0.1 C, and retains 3.45 mAh cm^-2 at 1 C, holding enormous potential for achieving energy-dense Li-S batteries.

Phase change material (PCM) can be incorporated with low-cost minerals to synthesis composite for thermal energy storage in building applications. Stone coal after vanadium extraction treatment shows potential in secondary utilization of composite preparation. This work prepared the stone coal-based composite PCM that stone coal as matrix, stearic acid as PCM, and expanded graphite as additive. To understand the effect of vanadium extraction on promotion of loading capacity and thermal conductivity, the analogous treatment of roasting and acid leaching on raw stone coal was conducted. Results show that the combined treatment of roasting at 900°C and leaching increases the loadage of stone coal in composite by 6.2% due to the improvement of specific surface area. Being contributed by 3% expanded graphite, both loading capacity and thermal conductivity of composite are obviously increased by 127% and 48.19%, respectively. Data is supported by the designed composite which has high loadage of 66.69% and thermal conductivity of 0.59 W m^-1 K^-1. The obtained composite exhibits phase change temperature of 52.17°C and melting latent heat of 121.5 J g^-1, as well as good chemical compatibility. The stone coal-based composite has prospects in building applications by taking advantage of secondary utilization of minerals.

3D reconstruction and quantitative characterization of the drainage channels and the coarse tailings particles in the bed were carried out in this study. The influence of the variations in the azimuthal angle (θ) and polar angle (φ) of the coarse particles on the drainage channel structure was analyzed, and the drainage mechanism of the bed was studied. Results show that water discharge in the bed reduces the size of pores and throat channels, increasing the slurry concentration. The throat channel structure is a key component of the drainage process. The φ and θ of the particles were changed predominantly along the length-axis direction. Changes in particle φ have a cumulative plugging effect on the drainage channel, and increase the difficulty of water discharge. The rake and rod form a shear ring in the tailings bed when with shear, and the rotation process realizes the particle θ from disorderly distribution to an orderly arrangement. The drainage channel is squeezed during the shearing process by the change in particle θ, which breaks the channel structure, encourages water discharge in the bed, and facilitates a further increase in slurry concentration. This finding is expected to offer theoretical guidance for preparing high-concentration underflow in the tailings thickening process.

There is a rise in demand for alternative low-grade iron ores, due to the rapid depletion of high-grade natural iron ore resources and an increase in the need for steel usage in daily life. However, using low-grade iron ores is always a clinical task for industry metallurgists. Direct smelting of low-grade ores consumes a lot of energy due to the large volume of slag generation. This can be avoided by direct reduction followed by magnetic separation (to separate the high gangue or refractory and metal parts) and smelting. Chromite overburden (COB) is a mine waste generated in chromite ore processing which mainly consists of iron, chromium and nickel (<1%). In the present work, the isothermal and non-isothermal kinetics of solid-state reduction of self-reduced pellets prepared by using low-grade iron ore (COB waste) were thoroughly investigated using thermal analysis. Results show that the reduction of pellets follows a first-order autocatalytic reaction control mechanism in the temperature range 900oC to 1100oC. The autocatalytic nature of the reduction reaction is due to the presence of nickel in the COB. The apparent activation energy values obtained from the kinetics results show that the solid-state reactions between COB and carbon are the rate-determining step in iron oxide reduction.

Mg-Zn-Ca-Mn series alloys are developed as promising candidates of 5G communication devices with high strength and excellent thermal conductivities. In present paper, extruded Mg-xZn-0.4Ca-0.2Mn (x=2, 4, 6 wt.%) alloys were prepared and the effect of Zn content on the mechanical and physical properties were investigated. The results showed that the addition of minor Ca led to the formation of Ca₂Mg₆Zn₃ eutectic phase at grain boundaries. A bimodal microstructure occurred in the as-extruded alloys, where elongated coarse deformed grains were embedded in refined recrystallized grains matrix. Correspondingly, both the yield strength and the ductility were significantly enhanced after extrusion due to the great grain refinement and random grain orientation of the recrystallized grains. Specially, higher yield strength and slightly reduced elongation were obtained in the alloys containing higher Zn content. Fine grain strengthening and basal texture strengthening were the main strengthening mechanisms for the as-extruded alloy. The thermal conductivity of as-extruded alloys was also improved compared with that of as-cast ones. The room temperature thermal conductivity of both as-cast and as-extruded alloys decreased with the increment of Zn content, which was due to the increased second phase fraction and solution atoms, that hindering the motion of the electrons. Mg-2Zn-0.4Ca-0.2Mn (wt.%) alloy in the as-extruded state exhibited a balanced mechanical properties and thermal properties, with ultimate tensile strength of 244.0 MPa, elongation to failure of 27.7% and thermal conductivity of 139.2 W/(m•K). The present paper may provide some scientific guidance for the preparation of lightweight materials with high ductility and high thermal conductivity materials.

The responsiveness to UV light only (~3.2 eV) and high photogenerated charge recombination rate are the two primary drawbacks of pure TiO₂. Accordingly, we combined N-doped graphene quantum dots (N-GQDs), morphology regulation, and heterojunction construction strategies to synthesize N-GQDs/N-TiO₂/P-doped porous hollow g-C₃N₄ nanotube (PCN) composite photocatalysts. The optimal sample (0.1%G-TPCN) exhibits significantly enhanced photoabsorption due to the change in bandgap caused by elemental doping (P, N), improved light harvesting resulting from hollow tube structure, and the upconversion effect of N-GQDs. In addition, the internal charge separation and transfer capability of 0.1%G-TPCN are dramatically boosted, and its carrier concentration is 3.7, 2.3, and 1.9 times that of N-TiO₂, PCN, and N-TiO₂/PCN (TPCN-1), respectively. This is attributed to the formation of Z-scheme heterojunction between N-TiO₂ and PCN, excellent electron conduction ability of N-GQDs, and shorter transfer distance by porous nanotube structure. Compared to N-TiO₂, PCN, and TPCN-1, H₂ production activity of 0.1%G-TPCN under visible light is enhanced by 12.4, 2.3, and 1.4 times, and ciprofloxacin (CIP) degradation rate is increased by 7.9, 5.7 and 2.9 times, respectively. The optimized performance is contributed to the excellent photoresponsiveness and improved carrier separation and migration efficiency. Finally, the photocatalytic mechanism of 0.1%G-TPCN and five possible degradation pathways of CIP were proposed. This study clarifies the mechanism of multiple modification strategies to synergistically improve the photocatalytic performance of 0.1%G-TPCN and also suggests a potential strategy for rationally designing novel photocatalysts for environmental remediation and solar energy conversion.

Exploring and designing a high-performance non-noble metal catalyst for hydrogen evolution reaction (HER) can be one of important factors for the large-scale application of H2 by water electrolysis. In this work, we reported novel catalysts with Ni-Mo nanoparticles decorated on reduced graphene oxide (NiMo@rGO) synthesized by a two-step hydrothermal method. The physical characterization results showed that the prepared NiMo@rGO-1 had irregular lamellar structure, and the Ni-Mo nanoparticles were uniformly dispersed on the rGO. NiMo@rGO-1 exhibited outstanding HER performance in alkaline environment, and it required only 93 and 180 mV overpotential for HER in 1.0 M KOH solution to obtain current densities of -10 and -50 mA cm⁻², respectively. In addition, the stability test of NiMo@rGO-1 showed that it had a certain operating stability for 32 h. In the same condition, the performance of NiMo@rGO-1 can be comparable to that of commercial Pt/C catalysts at high current density. The synergistic effect between Ni-Mo particles and lamellate graphene can significantly promote charge transfer in electrocatalytic reactions. As a result, NiMo@rGO-1 presented the advantages of high intrinsic activity, large specific surface area, and small electrical impedance. Meanwhile, the lamellar graphene played the role of dispersion to prevent the aggregation of nanoparticles. The preparation of NiMo@rGO-1 can be used in anion exchange membrane electrolysis of water to produce hydrogen. It provides a simple preparation method for efficient and low-cost water electrolysis to produce hydrogen in the future.

We constructed a machine learning (ML) model to predict the atmospheric corrosion rate of low-alloy steels (LAS). The material properties of LAS, environmental factors, and exposure time were used as the input, while the corrosion rate was obtained as the output. A total of six ML algorithms were used to construct the proposed model. Through optimization and filtering, the eXtreme gradient boosting (XGBoost) model exhibited good corrosion rate prediction accuracy. The features of material properties were then transformed into atomic and physical features using the proposed property transformation approach, and the dominant descriptors that affected the corrosion rate were filtered using the recursive feature elimination (RFE) as well as XGBoost methods. The established ML models exhibited better prediction performance and generalization ability via property transformation descriptors. In addition, we applied the SHapley Additive exPlanations (SHAP) method to analyze the relationship between these descriptors and the corrosion rate. The results showed that the property transformation model could effectively help with analyzing the corrosion behavior, thereby significantly improving the generalization ability of corrosion rate prediction models.

Efficient separation of chalcopyrite and galena is essential for optimal resource utilization. However, finding a selective depressant that is both environmentally friendly and cost-effective remains a challenge. This study explores the use of ferric ions (Fe³⁺) as a selective depressant for galena through various techniques such as micro-flotation tests, Fourier Transform Infrared Spectroscopy (FT-IR) analysis, Scanning Electron Microscope (SEM) observation, X-ray Photoelectron Spectroscopy (XPS) studies, and Raman Spectra measurements. The results of the flotation tests revealed the impressive selective inhibition capabilities of Fe³⁺ when used alone. Surface analysis showed that Fe³⁺ significantly reduced the adsorption of isopropyl ethyl thionocarbamate (IPETC) on the galena surface, while having minimal impact on chalcopyrite. Further analysis using SEM, XPS, and Raman spectra revealed that Fe³⁺ can oxidize lead sulfide (PbS) to form compact lead sulfate (PbSO₄) nanoparticles on the galena surface, effectively depressing IPETC adsorption and increasing surface hydrophilicity. These findings provide a promising solution for efficient and environmentally responsible separation of chalcopyrite and galena.

Rechargeable sodium-air batteries (SABs) are one of the most promising contestants in the field of energy storage and conversion. Despite the superior electrochemical performance of aqueous SABs, ensuring a long cycle life and high safety in practical applications of SABs remains challenging owing to the use of volatile aqueous electrolyte. In the paper, a novel quasi-solid-state SAB is fabricated by utilizing sodium biphenyl solution/carbon black composite (Na-BP-DME@C) anode and 92.5wt% succinonitrile (SN) plastic crystal cathode electrolyte. The gelatinous Na-BP-DME@C anode makes good interfacial contact with Na₃Zr₂Si₂PO₁₂ (NASICON), and facilitates interfacial electron transfer due to the high conductivity. In addition, 92.5wt% SN plastic crystal electrolyte is substituted for aqueous electrolyte, which has excellent stability to air, and ensures good physical contact and interfacial charge transfer kinetics between the catalytic cathode and NASICON. The constructed quasi-solid-state SAB exhibits a small voltage gap of 1.2 V, excellent cycle performance (nearly 374 h at 0.1 mA cm⁻²), and a high discharge capacity of 4.96 mAh at 0.5 mA cm⁻². This study provides a strategy for manufacturing quasi-solid-state SABs, which could greatly contribute to the development of solid-state metal-air batteries.

The amount of oxygen blown into the converter is one of the key parameters for the control of the converter blowing process, which directly affects the tap-to-tap time of converter. In this study, a hybrid model based on oxygen balance mechanism (OBM) and deep neural network (DNN) was established for predicting oxygen blowing time in converter. A three-step method was utilized in the hybrid model. Firstly, the oxygen consumption volume was predicted by the OBM model and DNN model, respectively. Secondly, a more accurate oxygen consumption volume was obtained by integrating the OBM model and DNN model. Finally, the converter oxygen blowing time was calculated according to the oxygen consumption volume and the oxygen supply intensity of each heat. The proposed hybrid model was verified using the actual data collected from an integrated steel plant in China, and compared with multiple linear regression model, OBM model, and neural network model including extreme learning machine, back propagation neural network, and DNN. The test results indicate that the hybrid model with a network structure of 3 hidden layer layers, 32-16-8 neurons per hidden layer, and 0.1 learning rate has the best prediction accuracy and stronger generalization ability compared with other models. The predicted hit ratio of oxygen consumption volume within the error ± 300 Nm³ is 96.67%; R² and RMSE are 0.6984 and 150.03 Nm³, respectively. The oxygen blow time prediction hit ratio within the error ± 0.6 min is 89.50%; R² and RMSE are 0.9486 and 0.3592 min, respectively. As a result, the proposed model can effectively predict the oxygen consumption volume and oxygen blowing time in the converter.

Engineering geological disasters such as rockburst have always been a critical factor affecting the safety of coal mine production. The study of residual stress is considered a feasible method for explaining these geomechanical phenomena. In this study, electron back-scattered diffraction (EBSD) and optical microscopes were utilized to characterize the rock microcosm. A measuring area that met the requirements of X-ray diffraction (XRD) residual stress measurement was determined to account for the mechanism of rock residual stress. The residual stress of siliceous slate-containing quartz vein was then measured and calculated using the sin²ψ method with an X-ray diffractometer. The analysis of microscopic test results showed that there were homogeneous areas with small-sized particles within the millimeter range, meeting the requirements of XRD stress measurement statistics. Quartz was determined as the calibration mineral for the slate samples containing quartz veins. The diffraction patterns of (324) crystal planes were obtained under different ψ and φ. The deviation direction of the diffraction peaks was consistent, proving that the sample tested had residual stress. In addition, the principal residual stress within the quartz vein measured by XRD was compressive, ranging from 10 to 33 MPa. The maximum principal stress was parallel to the vein trend, while the minimum principal stress was perpendicular to the vein trend. Furthermore, the content of the low-angle boundary and twin boundary in the quartz veins was relatively high, giving the rock mass stronger resistance to deformation and making it easier to form strain concentrations, resulting in residual stress. The proposed method for measuring residual stress can serve as a reference for subsequent observation and related research of residual stress in different types of rocks.

The waste heat was resumed from hot steel slag in a granular bed by the combination of numerical simulation and industrial test method. Firstly, the effective thermal conductivity of the granular bed was calculated, and then the unsteady state model was used to simulate the heat recovery from three different flow fields (O-type, S-type and Non shielding type (Non-type)). Secondly, the validation of simulation results was conducted by in-suit industrial experiments. Both of these two methods confirmed that the heat recovery efficiency of flow field order from high to low was Non-type, S-type and O-type. Finally, the heat recovery was carried out under Non-type flow field in industrial test, and the heat recovery efficiency increased from ~76%, ~78% to ~81% when the steel slag thickness decreased from 400, 300 to 200 mm, corresponding to the decrease of steel slag mass from 3.96, 2.97 to 1.98 t with a blower air volume of 14687 Nm³/h. Therefore, the research results showed that numerical simulation can not only guide the experiments of waste heat recovery, but also optimize the flow field. Most importantly, this method achieved a higher recovery rate of waste heat in industrial sense.

Traditional 3Ni weathering steel cannot fully meet the requirement of offshore engineering development, the design of novel 3Ni steel with the addition of micro-alloy element such as Mn or Nb to enhance the strength has become a trend. In this study, the stress-assisted corrosion behavior of the novel designed high strength 3Ni steel is studied by corrosion big data method. The information of the corrosion process was recorded by using galvanic corrosion current monitoring method. Gradient boosting decision tree (GBDT) machine-learning method was used to mining the corrosion mechanism and the importance of the structure factor was studied. Field exposure tests were held to verify the results calculated by GBDT method. Results depict that GBDT method can be used to effectively study the influence of structural factor on the corrosion process of 3Ni steel. Different mechanism for the addition of Mn and Cu on the stress-assisted corrosion of 3Ni steel suggest that Mn and Cu have no obvious effect on the corrosion rate of non-stressed 3Ni steel in the early stage of corrosion, when the corrosion reaches a stable state, the increase of Mn element content can increase the corrosion rate of 3Ni steel, while Cu reduces the corrosion rate of 3Ni steel. The increase of Mn element content and Cu addition could inhibit the corrosion process in the presence of stress. The corrosion law of outdoor exposure 3Ni steel is consistent with the law based on corrosion big data technology, which verifies the reliability of big data evaluation method and data prediction model selection.

The iron and steel industry of China faces urgent demands for both steel slag utilization and CO₂ abatement. Previous works have successfully modified the stainless steel slag for the dual goal of Cr immobilization and Ca/Mg recovery. In this paper, Ca-Mg-Si-Al solution is determined after acetic acid leaching treatment of modified stainless steel slag. The calcium-based sorbents are prepared from Ca-Mg (Si-Al) solution by co-precipitation. The effects of different contents of MgO on the morphology, structure, and CO₂ chemisorption capacity of the sorbents were investigated by doping the inert component MgO, and the skeleton support effect of MgO in calcium-based sorbents was determined. The chemisorption kinetics of the sorbents was studied using the Avrami-Erofeev model. There were two processes of CO₂ chemisorption, and the activation energy of the first stage (reaction control) was found to be lower than that of the second stage (diffusion control). The initial CO₂ chemisorption capacity of the sorbent prepared from the Ca-Mg-rich simulated solution was 0.60 g/g after pretreatment, and the initial CO₂ chemisorption capacity of the sorbent prepared from Ca-Mg-Si-Al solution was verified to be 0.4 g/g, which implies that part of the CO₂ emissions from steelmaking could be captured in this way.

In the last decades, vanadium alloyed coatings have been introduced as potential candidates for self-lubrication due to their perfect tribological properties. In this work, the influence of V incorporation on the wear performance and oxidation resistance of TiSiN/CrN films coatings deposited by D.C. reactive magnetron sputtering is investigated. The results show that vanadium incorporation significantly decreases the oxidation resistance of the coatings. In general, two layers are formed during the oxidation process: i) Ti(V)O₂ on top followed by a protective layer, which is subdivides into two layers: Cr₂O₃ and Si-O. The diffusion of V controls the oxidation process of V containing coatings. Addition of vanadium improves the wear resistance of coatings, and the wear rate decreases with increasing V content in the coatings, however, the friction coefficient is independently on the chemical composition of the coatings. The wear of the V-containing coatings is driven by polishing wear.

Bipolar electrochemistry is used to produce a linear potential gradient across a bipolar electrode (BPE), providing direct access to the anodic and cathodic reactions under a wide range of applied potentials. The occurrence of pitting corrosion, crevice corrosion, and general corrosion on type 2205 duplex stainless steel (DSS 2205) BPE has been observed at room temperature. The critical pit depth of 10-20 μm, with a 55-75% probability of pits developing into stable pits at potential from +0.9 V_OCP to +1.2 V_OCP are measured. All pit nucleation sites are either within ferritic grains or at the interface between austenite and ferrite. The critical conditions for pitting and crevice corrosion are discussed, with E_pit and E_crevice decreasing from 0.87 V_OCP /0.80 V_OCP after 150 s of exposure to 0.84 V_OCP/0.76 V_OCP after 900 s of exposure. Pit growth kinetics under different applied bipolar potentials and exposure times have been obtained. The ferrite is shown to be more susceptible to general dissolution.

Effectively strengthening the surface sulfidation is essential for recovering hemimorphite by froth flotation. In this work, ICP-OES measurements, Visual MINTEQ calculation, XPS analysis, ToF-SIMS analysis, and micro-flotation experiments were explored to systematically investigate the effect of ammonium sulfate ((NH₄)₂SO₄) on the formation of zinc sulfide species on hemimorphite surface and its role in sulfidation flotation. The results showed that (NH₄)₂SO₄ exhibited a positive influence on hemimorphite sulfidation flotation. It was ascribed to the number of zinc components in the form of Zn²⁺ and [Zn(NH₃)_i]²⁺ (i = 1 - 4) increased in the flotation system after hemimorphite treatment with (NH₄)₂SO₄, which was beneficial to its interaction with sulfur species in solution, resulting in a dense and stable zinc sulfide layer was generated on the hemimorphite surface. [Zn(NH₃)_i]²⁺ participated in the sulfidation reaction of hemimorphite as a transition state. In addition, the sulfidation reaction of hemimorphite was accelerated by (NH₄)₂SO₄. Thus, (NH₄)₂SO₄ presents a vital role in promoting the sulfidation of hemimorphite.

The tensile properties of 2297-T87 Al-Li alloy thick plate at different thickness positions and in different directions were analyzed by means of tensile test, optical microscopy (OM), X-ray diffraction, scanning electron microscopy (SEM), energy dispersive spectrometry (EDS) and transmission electron microscopy (TEM). The results show that the ultimate tensile strength (UTS) and yield strength (YS) of the alloy decrease first and then increase from the 1/8T position to the 1/2T position, whilst the elongation to failure (E_f) decrease gradually that the values of E_f along the rolling direction (RD) is higher than that along the transverse direction (TD) at the same thickness position. From the 1/8T position to the 3/8T position of the alloy, the UTS and YS values along the TD are higher than that along the RD. At the 1/2T position of the alloy, the values of the UTS, YS and E_f along the RD are the highest, whilst that along the normal direction (ND) are the lowest. Microstructure observations revealed that the anisotropy of tensile properties is related to grain morphology, crystal texture, second-phase-particles and Li atom segregation.

The solution and quenching heat treatment are generally carried out in a roller hearth furnace for large-scale aluminum alloy thick plates. However, the asymmetric or uneven spray water flow rate is inevitable under industrial production conditions which leads to asymmetric residual stress distribution. In this paper, the spray quenching treatment was conducted on self-designed spray equipment and the residual stress along thickness direction was measured by layer removal method based on deflections. With the asymmetric spray quenching condition, the subsurface stress of the higher flow rate surface is lower than that of the lower flow rate surface and the difference between the two subsurface stresses increases with the increasing of difference in water flow rates. The subsurface stress underneath surface with water flow rate of 0.60 m³/h is 15.38 MPa less than the one of 0.15 m³/h. The simulated residual stress by FEM of the higher HTC surface is less than that of the lower HTC surface which is consistent with experimental results. The FE model can be used to analyze the strain and stress evolution and to predict quenched stress magnitude and distribution.

For the comprehensive utilization of ludwigite ore, an integrated route for the efficient boron and iron separation was proposed in this work, via soda-ash roasting under CO-CO₂-N₂ atmospheres followed by grind-leaching, magnetic separation and CO₂ carbonation. Influences of roasting temperature, roasting time, CO/(CO+CO₂) composition and Na₂CO₃ dosage were primarily investigated. Under the optimized conditions of the roasting temperature of 850^oC, roasting time of 60 min, soda ash dosage of 20wt% and CO/(CO+CO₂) of 10%, 92wt% of boron was leached during wet grinding, and 88.6wt% of iron was recovered in the magnetic concentrate with a total iron content of 61.51wt%. Raman spectra and 11B NMR results indicate that boron exists as B(OH)₄^- in the leachate, from which high-purity borax pentahydrate could be prepared by CO₂ carbonation.

Porous magnesium strontium phosphate (Sr_3-xMg_x(PO₄)₂) (x=2, 2.5, 3) composite scaffolds were successfully prepared by 3D gel-printing (3DGP) method in this study. The results show that Sr_0.5Mg_2.5(PO₄)₂ scaffolds had good compressive strength, and Sr_1.0Mg_2.0(PO₄)₂ scaffolds had good degradation rate in vitro. The weight loss rate of Sr_1.0Mg_2.0(PO₄)₂ scaffolds soaked in SBF for 6 weeks was 6.96%, and pH value varied between 7.50 and 8.61, which was within the acceptable range of human body. Preliminary biological experiment shows that MC3T3-E1 cells had good adhesion and proliferation on the surface of Sr_3-xMg_x(PO₄)₂ scaffolds. Compared with pure Mg₃(PO₄)2 scaffolds, strontium doped scaffolds had excellent comprehensive properties, which explain that Sr_3-xMg_x(PO₄)₂ composite scaffolds can be used for bone tissue engineering.

Coal gasification fine slag (FS) is a typical solid waste generated in the coal gasification process, and its current disposal methods of stockpiling and landfilling have caused serious soil and ecological hazards. Separation recovery and high-value utilization of residual carbon (RC) in FS is the key to realize the win-win situation of coal chemical industry in terms of economic and environmental benefits. The structural properties such as pore structure, surface functional group structure, and microcrystalline structure of RC in FS (FS-RC) not only affect the flotation recovery efficiency of FS-RC, but also form the basis for the high-value utilization of FS-RC. In this paper, the characteristics of FS-RC in terms of pore structure, surface functional groups, and microcrystalline structure are sorted out from the type of gasification process and the particle size of FS, and the reasons for the formation of its special structural properties are analyzed, and its influence on flotation separation and high-value utilization of FS-RC is summarized. Based on the pore structure characteristics of FS-RC, it is proposed that separation methods such as "ultrasonic pretreatment - pore blocking flotation" and "pore breaking - flocculation flotation" may be the key development technology to improve the FS-RC recovery in the future; based on the surface structure and microcrystalline structure of FS-RC, it is proposed that design of low-cost, low-dose collectors containing polar bond is an important breakthrough point to strengthen the flotation efficiency of FS-RC in the future. High-value utilization of FS should be based on the physicochemical structural properties of FS-RC, and should focus on the environmental impact of hazardous elements and the recyclability of chemical waste liquid to form an environmentally friendly utilization method. This review is of great theoretical significance for the comprehensive understanding of the unique structural properties of FS-RC, the breakthrough of the technological bottleneck in the efficient flotation separation of FS, as well as the expansion of the field of high value-added utilization of FS-RC.

Plastic instability, including both the discontinuous yielding and stress serrations, has been frequently observed during the tensile deformation of medium Mn steels (MMnS) and then be intensively studied recently. Unfortunately, many research results are controversial and a universal agreement has not been made yet. Here we first summarized all the possible factors that affect the yielding and the flow stress serrations in MMnS, including the morphology and stability of austenite, the feature of phase interface, and the deformation parameters; and then tried to propose a universal mechanism to explain the conflicting experimental results. We conclude that the discontinuous yielding is attributed to the lack of mobile dislocation before deformation and the rapid dislocation multiplication at the beginning of plastic deformation, while the stress serrations are formed due to the pinning and depinning between dislocations and interstitial atoms in austenite. Strain induced martensitic transformation, influenced by mechanical stability of austenite grain and deformation parameters, should not be the intrinsic cause of plastic instability but it can intensify or weaken the discontinuous yielding and the stress serrations by affecting the mobility and density of dislocations, and the interaction between the interstitial atoms and dislocations in austenite grains.

The mechanisms of oxide metallurgy technology include inducing IAF using micron-sized inclusions and restricting the growth of prior austenite grains (PAGs) by nano-sized particles during the welding process. The typical oxide metallurgy technologies include the HTUFF technology, JFE EWEL, KST technology, the ETISD technology, and so on. The complex deoxidation of Ti with other strong deoxidant elements such as Mg, Ca, Zr and rare earth metals (REM) can improve the HAZ toughness. The Mg addition is more effective in promoting the precipitation of TiN particles to refine the PAG size. The Ca addition can effectively improve the IAF nucleation due to the formation of Ca oxysulfide. Zr-containing inclusions are also effective in inducing IAF nucleation. REM can refine precipitates and induce IAF. Increasing C, Si, Al, Nb, Cr content will all impair the HAZ toughness. Higher C content usually increase the number of coarse carbides and decrease the potency of the IAF formation. The Si and Cr addition both lead to the formation of undesirable microstructures. The high Al content in steel is not beneficial to the IAF nucleation due to the formation of Al₂O₃ inclusions. Nb is soluble in TiN particles to form (Ti,Nb)(C,N) particles which have poor high-temperature stability. On the other hand, Mo, V and B can enhance the HAZ toughness. Mo-containing precipitates seem to present better thermal stability, and increasing Mo content can refine precipitates. VN or V(C, N) prefers to be effective in promoting the nucleation of IAF due the good crystallographic coherent relationship with ferrite. The segregation of B atoms at the PAG boundary and the B depleted zone around inclusion will promote the formation of IAF.

Compared with the traditional plastic forming technology, ultrasonic vibration plastic forming has the advantages of reducing the forming force and improving the surface quality of the workpiece. It has a very broad application prospect in the industrial manufacturing field. In recent years, researchers have conducted extensive research in ultrasonic vibration plastic forming of metals. A deep foundation has been laid for the development of this field. This study classified metals according to their crystal structures. The effects of ultrasonic vibration on the microstructure during plastic forming of face centered cubic (FCC), body centered cubic (BCC) and hexagonal close packed (HCP) metals and the forming mechanism of ultrasonic vibration were reviewed. The main problems and future research direction of ultrasonic vibration plastic forming of metals were pointed out.

In the traditional long process of steelmaking, excess oxygen is blown into the converter, and then alloying elements are used for deoxidation. This inevitably results in a large amount of deoxidation products remaining in the steel liquid, affecting the cleanliness of the steel. With the increasing requirements for steel performance, it is necessary to not only reduce the oxygen content in the steel liquid, but also ensure its high cleanliness. After more than a hundred years of development, the total oxygen content in steel has been reduced from over 100×10^-6 to around 10×10^-6, and it can even be controlled below 5×10^-6 in some steel grades. A relatively stable and mature deoxidation technology has been formed, but further reducing the oxygen content in steel is no longer significant for improving steel quality. Our research team has developed a deoxidation technology for bearing steel based on the optimization of the entire process. It is a combination of silicon-manganese pre-deoxidation, ladle furnace diffusion deoxidation, and vacuum final deoxidation. We have successfully conducted industrial experiments on the production technology of interstitial free steel with natural decarbonization pre-deoxidation. The former can control the oxygen content in bearing steel to between 4-8×10^-6, change the type of inclusions, eliminate large particle Ds-type inclusions, improve the flowability of the steel liquid, and obtain a higher fatigue life. The latter not only reduces aluminum consumption and production costs but also significantly improves the quality of cast billets.

Cobalt has excellent electrochemical, magnetic, and heat properties. As a strategic resource, it has been applied in many high-tech products. However, the rapid growth of the battery industry in recent years has resulted in a significant depletion of cobalt resources, leading to a crisis of cobalt resources supply. The paper examines cobalt ore reserve and distribution, and summarizes recent development and consumption of cobalt resources. And the principles, advantages and disadvantages, and research status of various methods are discussed comprehensively. It can be concluded that the utilization of diverse sources (Cu-Co ores, Ni-Co ores, zinc plant residues, and waste cobalt products) for producing cobalt will be enhanced to meet developmental requirements. And in recovering technology, the pyro-hydrometallurgical process employs pyrometallurgy as the pre-treatment to modify the phase structure of cobalt minerals, enhancing its recovery in the hydrometallurgical stage and facilitating high-purity cobalt production. Consequently, it represents a highly promising technology for future cobalt recovery. Lastly, based on the above conclusions, the prospects for cobalt, in terms of cobalt ores processing and sustainable cobalt recycling for which further study should be conducted in the future.

The laser powder bed fusion (LPBF) process can integrally form geometrically complex and high-performance metallic parts that have attracted much interest, especially in the mold industry. The appearance of the LPBF makes it possible to design and produce complex conformal cooling channel systems in molds. Thus, LPBF-processed tool steels have been widely studied. The complex thermal history in the LPBF process makes the microstructural characteristics and properties different from those of conventional manufactured tool steels. This paper provides an overview of LPBF-processed tool steels by describing the physical phenomena, the microstructural characteristics, and the mechanical/thermal properties, including tensile properties, wear resistance, and thermal properties. The microstructural characteristics are presented through a multiscale perspective, ranging from densification, meso-structure, microstructure, substructure in grains, to nanoprecipitates. Finally, a summary of tool steels and their challenges and outlooks are introduced.

Hypo-peritectic steel is widely used in many industrial fields attributed to its excellent combination of high strength, high toughness, high processability, high weldability and low material cost. However, surface defects are quite liable to occur during continuous casting, including depression, longitudinal crack, deep oscillation mark, and severe level fluctuation with slag entrapment. It is still a great challenge to produce hypo-peritectic steel in high efficiency mode by continuous casting due to the limited understanding on the mechanism of peritectic solidification. This work reviews the definition and classification of hypo-peritectic steel, and introduces the formation tendency of common surface defects related to peritectic solidification. The new achievements on the mechanism of peritectic reaction and transformation have been listed. At last, the countermeasures to avoid the surface defects of hypo- peritectic steel has been summarized. It is helpful for the researcher to get some enlightening points in continuous casting of hypo-peritectic steel and develop new technique to overcome the present problems.

The metal to insulator transitions (MIT) as achieved in 3d-band correlated transitional metal oxides triggers abrupt variations in the electrical, optical and/or magnetic properties, beyond conventional semiconductors. Among such material families, the ion (Fe: 3d⁶4s²) containing oxides are interesting owing to their widely tunable MIT properties associated with various valance states of Fe, while their potential electronic applications are also promising noticing the large abundance of Fe on earth. Representative MIT properties triggered by critical temperature (T_MIT) were reported for ReFe₂O₄ (Fe^2.5+), ReBaFe₂O₅ (Fe^2.5+), Fe₃O₄ (Fe^2.67+), Re_1/3Sr_2/3FeO₃ (Fe^3.67+), ReCu₃Fe₄O₁₂ (Fe^3.75+) and Ca_1-xSr_xFeO₃ (Fe⁴⁺). It is also interesting to note the common feature in MITs of these Fe containing oxides that are usually accompanied by the charge ordering transitions or disproportionation associated with the valance states of Fe. Herein, we review the material family of the Fe-containing MIT oxides, their MIT functionalities and the respective mechanisms. From the perspective of potential correlated electronic applications, the tunability in the critical temperatures associated with MIT (T_MIT) and its resultant resistive change are summarized for the Fe-containing oxides and further compared to other materials exhibiting the MIT functionality. In particular, we highlight the abrupt MIT and wide tunability in T_MIT for the Fe-containing quadruple perovskites, such as ReCu₃Fe₄O₁₂, while their more effective material synthesis is yet required to be further explored to cater for potential applications.

The flotation separation of Cu–Fe sulfide minerals at low alkalinity can be achieved using selective depressants. In the flotation system of Cu–Fe sulfide minerals, depressants usually preferentially interact with the pyrite surface to render the mineral surface hydrophilic and hinder collector adsorption. This study summarizes advances in depressants for the flotation separation of Cu–Fe sulfide minerals at low alkalinity. These include inorganic depressants (oxidants and sulfur-oxygen compounds), natural polysaccharides (starch, dextrin, konjac glucomannan, and galactomannan), modified polymers (carboxymethyl cellulose, polyacrylamide, lignosulfonate, and tricarboxylate sodium starch), organic acids (polyglutamic acid, sodium humate, tannic acid, pyrogallic acid, salicylic acid, and lactic acid), sodium dimethyl dithiocarbamate, and diethylenetriamine. The potential application of specific inorganic and organic depressants in the flotation separation of Cu–Fe sulfide minerals with low alkalinity is reviewed. This paper comprehensively discusses advances in the use of organic depressants in the flotation separation of Cu–Fe sulfide minerals and summarizes the depression performance and mechanism of different types of organic depressants on mineral surfaces. Finally, perspectives on depressants in the flotation separation of Cu–Fe sulfide minerals at low alkalinity are proposed.

This article provides an overview of the latest developments in metal-covalent organic framework (MCOF) and covalent metal-organic framework (CMOF) materials, whose construction entails a combination of both reversible coordination and covalent bonding adapted from metal-organic frameworks (MOFs) and covalent organic frameworks (COFs), respectively. With an emphasis on the structures of MCOFs and CMOFs, this review surveys representative materials’ building blocks and topologies. Specifically, the frameworks are classified based on the dimensions of their components (building blocks): discrete building blocks and 1D infinite building blocks. For the first category, the materials were further divided into collections of two-dimensional (2D) networks and three-dimensional (3D) networks according to their topologies. For the second category, this article mainly covers the recently emerging MCOFs with woven structures. Finally, state-of-the-art in MCOF and CMOF chemistry has laid out promising avenues for future development.

Metal corrosion can result in significant economic losses, safety issues, and environmental pollution, which has attracted great research interests. Carbon dots (CDs), a new class of zero-dimensional carbon nanomaterials, have recently been proposed for corrosion protection applications due to their excellent properties such as corrosion inhibition effect, fluorescence property, low toxicity, facile chemical modification, and cost-effectiveness. This study provides a comprehensive overview of the preparation methods, physical and chemical properties, and anti-corrosion mechanisms of functional CDs. The corrosion inhibition performance of different kinds of CDs is first introduced, followed by the discussions on application of CDs in the development of smart protective coatings with self-healing and/or self-reporting properties. The effective barrier formed by CDs in the coatings can inhibit local damage expansion and achieve the self-healing property. In addition, the diverse functional groups of CDs can interact with Fe³⁺ and H⁺ ions generated during corrosion process to change the fluorescence of CDs, so as to achieve the self-reporting property. More importantly, the challenges and future prospects for the development of CDs-based corrosion protection systems are proposed.

With the development of automation and informatization in the steelmaking industry, the human brain is gradually unable to cope with more and more data generated during the steelmaking process. Machine learning technology provides a new method other than production experience and metallurgical principle in dealing with the large amounts of data. The application of the machine learning in the steelmaking process has become a research hotspot in recent years. This paper provides an overview of the applications of machine learning in the steelmaking process modeling involving hot metal pretreatment, primary steelmaking, secondary refining and some other aspects The three most frequently used machine learning algorithms in steelmaking process modeling are artificial neural network, support vector machine and case-based reasoning, with the proportions of 56%, 14 % and 10%, respectively. Since the data collected in the steelmaking plants are frequently faulty, the data processing, especially the data cleaning, is crucially important to the performance of machine learning model. The detection of variable importance can be used to optimize the process parameters and guide the production. Machine learning is used in hot metal pretreatment modeling mainly for the endpoint S content prediction. The predictions of the endpoints of element compositions and the process parameters are widely investigated in the primary steelmaking. Machine learning is used in the secondary refining modeling mainly for LF (ladle furnace), RH (Ruhrstahl Heraeus), VD (vacuum degassing), AOD (argon oxygen decarburization) and VOD (vacuum oxygen decarburization) processes. For the further development of machine learning in the steelmaking process modeling, more efforts should be made in the construction of the data platform, the industrial transformation of the research achievements to the practical steelmaking process, and the improvement of the universality of the machine learning models.