International Journal of Minerals, Metallurgy and Materials

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Effects and mechanisms of fluorite on the co-reduction of blast furnace dust and seaside titanomagnetite

Tian-yang Hu, Ti-chang Sun, Jue Kou, Chao Geng, Yong-qiang Zhao

2017, 24(11): 1201-1210. doi: 10.1007/s12613-017-1512-4

中文摘要(469) PDF(15) SpringerLink

摘要:
The co-reduction roasting and grinding magne -tic separation of seaside titanomagnetite and blast furnace dust was investigated with and without fluorite addition at a reduction roasting temperature of 1250℃ for 60 min, a grinding fineness of -43 μm accounting for 69.02wt% of the total, and a low-intensity magnetic field strength of 151 kA/m. The mineral composition, microstructure, and state of the roasted products were analyzed, and the concentrations of CO and CO₂ were analyzed in the co-reduction roasting. Better results were achieved with a small fluorite dosage (≤ 4wt%) in the process of co-reduction. In addition, F^- was found to reduce the melting point and viscosity of the slag phase because of the high content of aluminate and silicate minerals in the blast furnace dust. The low moisture content of the blast furnace dust and calcic minerals inhibited the hydrolysis of CaF₂ and the loss of F^-. Compared with the blast furnace dust from Chengdeng, the blast furnace dusts from Jiugang and Jinxin inhibited the diffusion of F^- when used as reducing agents, leading to weaker effects of fluorite.

研究论文

Sulfuric acid leaching of high iron-bearing zinc calcine

Jin-lin Yang, Ji-guang Liu, Han-xin Xiao, Shao-jian Ma

2017, 24(11): 1211-1216. doi: 10.1007/s12613-017-1513-3

中文摘要(479) PDF(12) SpringerLink

摘要:
Sulfuric acid leaching of high iron-bearing zinc calcine was investigated to assess the effects of sulfuric acid concentration, liquid-to-solid ratio, leaching time, leaching temperature, and the stirring speed on the leaching rates of zinc and iron. The results showed that the sulfuric acid concentration, liquid-to-solid ratio, leaching time, and leaching temperature strongly influenced the leaching of zinc and iron, whereas stirring speed had little influence. Zinc was mainly leached and the leaching rate of iron was low when the sulfuric acid concentration was less than 100 g/L. At sulfuric acid concentrations higher than 100 g/L, the leaching rate of iron increased quickly with increasing sulfuric acid concentration. This behavior is attributed to iron-bearing minerals such as zinc ferrite in zinc calcine dissolving at high temperatures and high sulfuric acid concentrations but not at low temperatures and low sulfuric acid concentrations.

研究论文

Deep cleaning of a metallurgical zinc leaching residue and recovery of valuable metals

Peng Xing, Bao-zhong Ma, Peng Zeng, Cheng-yan Wang, Ling Wang, Yong-lu Zhang, Yong-qiang Chen, Shuo Wang, Qiu-yin Wang

2017, 24(11): 1217-1227. doi: 10.1007/s12613-017-1514-2

中文摘要(652) PDF(29) SpringerLink

摘要:
Huge quantities of zinc leaching residues (ZLRs) generated from zinc production are dumped continuously around the world and pose a potential environmental threat because of their considerable amounts of entrained heavy metals (mainly lead). Most ZLRs have not been properly treated and the valuable metals in them have not yet been effectively recovered. Herein, the deep cleaning of a ZLR and recovery of valuable metals via a hydrometallurgical route were investigated. The cleaning process consists of two essential stages:acid leaching followed by calcium chloride leaching. The optimum conditions for extracting zinc, copper, and indium by acid leaching were a sulfuric acid concentration of 200 g·L^-1, a liquid/solid ratio of 4:1 (mL/g), a leaching time of 2 h, and a temperature of 90℃. For lead and silver extractions, the optimum conditions were a calcium chloride concentration of 400 g·L^-1, a pH value of 1.0, a leaching time of 1 h, and a temperature of 30℃. After calcium chloride leaching, silver and lead were extracted out and the lead was finally recovered as electrolytic lead by electrowinning. The anglesite phase, which poses the greatest potential environmental hazard, was removed from the ZLR after deep cleaning, thus reducing the cost of environmental management of ZLRs. The treatment of chlorine and spent electrolyte generated in the process was discussed.

研究论文

Effect of diboron trioxide on the crushing strength and smelting mechanism of high-chromium vanadium-titanium magnetite pellets

Gong-jin Cheng, Zi-xian Gao, He Yang, Xiang-xin Xue

2017, 24(11): 1228-1240. doi: 10.1007/s12613-017-1515-1

中文摘要(505) PDF(12) SpringerLink

摘要:
The effect of diboron trioxide (B₂O₃) on the crushing strength and smelting mechanism of high-chromium vanadium-titanium magnetite pellets was investigated in this work. The main characterization methods were X-ray fluorescence, inductively coupled plasma-atomic emission spectroscopy, mercury injection porosimetry, X-ray diffraction, metallographic microscopy, and scanning electron microscopy-energy-dispersive X-ray spectroscopy. The results showed that the crushing strength increased greatly with increasing B₂O₃ content and that the increase in crushing strength was strongly correlated with a decrease in porosity, the formation of liquid phases, and the growth and recrystallization consolidation of hematite crystalline grains. The smelting properties were measured under simulated blast furnace conditions; the results showed that the smelting properties within a certain B₂O₃ content range were improved and optimized except in the softening stage. The valuable element B was easily transformed to the slag, and this phenomenon became increasingly evident with increasing B₂O₃ content. The formation of Ti(C,N) was mostly avoided, and the slag and melted iron were separated well during smelting with the addition of B₂O₃. The size increase of the melted iron was consistent with the gradual optimization of the dripping characteristics with increasing B₂O₃ content.

研究论文

Utilization of gold-bearing and iron-rich pyrite cinder via a chlorination-volatilization process

Jian Ding, Pei-wei Han, Cui-cui Lü, Peng Qian, Shu-feng Ye, Yun-fa Chen

2017, 24(11): 1241-1250. doi: 10.1007/s12613-017-1516-0

中文摘要(536) PDF(10) SpringerLink

摘要:
The chlorination-volatilization process has been adopted to make full use of gold-bearing and iron-rich pyrite cinder. However, problems of low recovery rate, pulverization of pellets, and ring formation have been encountered during the industrialization of this process. The effects of various parameters on the volatilization rates of valuable metals and on the compressive strength of roasted pellets were investigated in this paper. The parameters include the CaCl₂ dosage, heating temperature, and holding time. The results show that heating temperature is the most important parameter for the recovery of target metals. More CaCl₂ was needed for the recovery of zinc than for the recovery of gold, silver, and lead. CaCl₂ started to react with sulfides/SO₂/SiO₂ at temperatures below the melting point of CaCl₂ to generate Cl₂/HCl. Gaseous CaCl₂ was formed at higher temperatures and could react with any of the components. The compressive strength of roasted CaCl₂-bearing pellets first decreased slowly with increasing temperature at temperatures lower than 873 K, which could result in the pulverization of pellets during heating. Their compressive strength increased dramatically with increasing temperature at temperatures greater than 1273 K. Certain quantities of CaCl₂ and Fe(Ⅱ) could improve the compressive strength of the roasted pellets; however, the addition of excessive CaCl₂ decreased the compressive strength of pellets.

研究论文

Mechanism and simulation of droplet coalescence in molten steel

Bing Ni, Tao Zhang, Hai-qi Ni, Zhi-guo Luo

2017, 24(11): 1251-1259. doi: 10.1007/s12613-017-1517-z

中文摘要(605) PDF(21) SpringerLink

摘要:
Droplet coalescence in liquid steel was carefully investigated through observations of the distribution pattern of inclusions in solidified steel samples. The process of droplet coalescence was slow, and the critical Weber number (We) was used to evaluate the coalescence or separation of droplets. The relationship between the collision parameter and the critical We indicated whether slow coalescence or bouncing of droplets occurred. The critical We was 5.5, which means that the droplets gradually coalesce when We ≤ 5.5, whereas they bounce when We > 5.5. For the carbonate wire feeding into liquid steel, a mathematical model implementing a combined computational fluid dynamics (CFD)-discrete element method (DEM) approach was developed to simulate the movement and coalescence of variably sized droplets in a bottom-argon-blowing ladle. In the CFD model, the flow field was solved on the premise that the fluid was a continuous medium. Meanwhile, the droplets were dispersed in the DEM model, and the coalescence criterion of the particles was added to simulate the collision-coalescence process of the particles. The numerical simulation results and observations of inclusion coalescence in steel samples are consistent.

研究论文Open Access

Effects of chitosan inhibitor on the electrochemical corrosion behavior of 2205 duplex stainless steel

Se-fei Yang, Ying Wen, Pan Yi, Kui Xiao, Chao-fang Dong

2017, 24(11): 1260-1266. doi: 10.1007/s12613-017-1518-y

中文摘要(707) PDF(17) SpringerLink

摘要:
The effects of chitosan inhibitor on the corrosion behavior of 2205 duplex stainless steel were studied by electrochemical measurements, immersion tests, and stereology microscopy. The influences of immersion time, temperature, and chitosan concentration on the corrosion inhibition performance of chitosan were investigated. The optimum parameters of water-soluble chitosan on the corrosion inhibition performance of 2205 duplex stainless steel were also determined. The water-soluble chitosan showed excellent corrosion inhibition performance on the 2205 duplex stainless steel. Polarization curves demonstrated that chitosan acted as a mixed-type inhibitor. When the stainless steel specimen was immersed in the 0.2 g/L chitosan solution for 4 h, a dense and uniform adsorption film covered the sample surface and the inhibition efficiency (IE) reached its maximum value. Moreover, temperature was found to strongly influence the corrosion inhibition of chitosan; the inhibition efficiency gradually decreased with increasing temperature. The 2205 duplex stainless steel specimen immersed in 0.4 g/L water-soluble chitosan at 30℃ displayed the best corrosion inhibition among the investigated specimens. Moreover, chitosan decreased the corrosion rate of the 2205 duplex stainless steel in an FeCl₃ solution.

研究论文

Effects of heat treatment on the intermetallic compounds and mechanical properties of the stainless steel 321-aluminum 1230 explosive-welding interface

Mohammadreza Khanzadeh Gharah Shiran, Gholamreza Khalaj, Hesam Pouraliakbar, Mohamma dreza Jandaghi, Hamid Bakhtiari, Masoud Shirazi

2017, 24(11): 1267-1277. doi: 10.1007/s12613-017-1519-x

中文摘要(780) PDF(28) SpringerLink

摘要:
The effects of heat treatment on the microstructure and mechanical properties of intermetallic compounds in the interface of stainless steel 321 explosively bonded to aluminum 1230 were investigated in this study. Experimental investigations were performed by optical microscopy, scanning electron microscopy, and microhardness and shear tensile strength testing. Prior to heat treatment, increasing the stand-off distance between samples from 1 to 2.5 mm caused their interface to become wavy and the thickness of intermetallic layers to increase from 3.5 to 102.3 μm. The microhardness increased from HV 766 in the sample prepared at a stand-off distance of 1 mm to HV 927 in the sample prepared at a stand-off distance of 2.5 mm; in addition, the sample strength increased from 103.2 to 214.5 MPa. Heat treatment at 450℃ for 6 h increased the thickness of intermetallic compound layers to 4.4 and 118.5 μm in the samples prepared at stand-off distances of 1 and 2.5 mm, respectively. These results indicated that increasing the duration and temperature of heat treatment decreased the microhardness and strength of the interface of explosively welded stainless steel 321-Al 1230 and increased the thickness of the intermetallic region.

研究论文Open Access

Solid FeS lubricant:a possible alternative to MoS₂ for Cu-Fe-based friction materials

Tao Peng, Qing-zhi Yan, Xiao-lu Zhang, Xiao-jiao Shi

2017, 24(11): 1278-1283. doi: 10.1007/s12613-017-1520-4

中文摘要(573) PDF(18) SpringerLink

摘要:
Molybdenum disulfide (MoS₂) is one of the most commonly used solid lubricants for Cu-Fe-based friction materials. Nevertheless, MoS₂ reacts with metal matrices to produce metal sulfides (e.g., FeS) and Mo during sintering, and the lubricity of the composite may be related to the generation of FeS. Herein, the use of FeS as an alternative to MoS₂ for producing Cu-Fe-based friction materials was investigated. According to the reaction principle of thermodynamics, two composites-one with MoS₂ (Fe-Cu-MoS₂ sample) and the other with FeS (FeS-Cu₂S-Cu-Fe-Mo sample), were prepared and their friction behaviors and mechanical properties were compared. The results showed that MoS₂ reacted with the Cu-Fe matrix to produce FeS, metallic ternary sulfides, and Mo when sintered at 1050℃. The MoS₂-Cu-Fe and FeS-Cu₂S-Cu-Fe-Mo samples thereby exhibited similar characteristics with respect to phase composition, density, hardness, and tribological behaviors. Micrographs of the worn surfaces revealed that the stable friction regime for both composites stemmed from the iron sulfides friction layers rather than from the molybdenum sulfides layers.

研究论文Open Access

Effect of pre-annealing treatment on the microstructure and mechanical properties of extruded Al-Zn-Mg-Cu alloy bars

Zhi-hao Zhang, Jie Xue, Yan-bin Jiang, Feng Jin

2017, 24(11): 1284-1292. doi: 10.1007/s12613-017-1521-3

中文摘要(509) PDF(11) SpringerLink

摘要:
Taking extruded Al-Zn-Mg-Cu alloy (7A04 alloy) bars as the research object, the effect and mechanism of pre-annealing treatments on the microstructure and mechanical properties of the aged alloy bars were investigated. The results show that a pre-annealing treatment at 350℃ for 15 h before a T6 treatment substantially reduced the sensitivity of the microstructure and mechanical properties of the extruded 7A04 aluminum alloy specimens toward the extrusion temperature. The average grain sizes of the specimens extruded at 390 and 430℃ after T6 treatment were 3.4 and 8.1 μm, respectively, and their elongations to failure were 7.0% and 9.2%, respectively. However, after pre-annealing + T6 treatment, the differences in both the grain sizes and the elongations of the specimens became small, i.e., their average grain sizes were 3.2 and 3.8 μm and their elongations were 12.0% and 13.3%, respectively. For the specimens extruded at the same temperature, pre-annealing treatment obviously improved the plasticity of the alloy, which is attributed to an increase in soft texture or to grain refinement in the specimens as a result of the pre-annealing + T6 treatment.

研究论文

Corrosion behavior of ultrafine-grained AA2024 aluminum alloy produced by cryorolling

P. Laxman Mani Kanta, V. C. Srivastava, K. Venkateswarlu, Sharma Paswan, B. Mahato, Goutam Das, K. Sivaprasad, K. Gopala Krishna

2017, 24(11): 1293-1305. doi: 10.1007/s12613-017-1522-2

中文摘要(611) PDF(29) SpringerLink

摘要:
The objectives of this study were to produce ultrafine-grained (UFG) AA2024 aluminum alloy by cryorolling followed by aging and to evaluate its corrosion behavior. Solutionized samples were cryorolled to ~85% reduction in thickness. Subsequent aging resulted in a UFG structure with finer precipitates of Al₂CuMg in the cryorolled alloy. The (1) solutionized and (2) solutionized and cryorolled samples were uniformly aged at 160℃/24 h and were designated as CGPA and CRPA, respectively; these samples were subsequently subjected to corrosion studies. Potentiodynamic polarization studies in 3.5wt% NaCl solution indicated an increase in corrosion potential and a decrease in corrosion current density for CRPA compared to CGPA. In the case of CRPA, electrochemical impedance spectroscopic studies indicated the presence of two complex passive oxide layers with a higher charge transfer resistance and lower mass loss during intergranular corrosion tests. The improved corrosion resistance of CRPA was mainly attributed to its UFG structure, uniform distribution of fine precipitates, and absence of coarse grain-boundary precipitation and associated precipitate-free zones as compared with the CGPA alloy.

研究论文

Solidification, microstructure, and mechanical properties of the as-cast ZRE1 magnesium alloy with different praseodymium contents

Z. M. Sheggaf, R. Ahmad, M. B. A. Asmael, A. M. M. Elaswad

2017, 24(11): 1306-1320. doi: 10.1007/s12613-017-1523-1

中文摘要(579) PDF(11) SpringerLink

摘要:
The influence of praseodymium (Pr) content on the solidification characteristics, microstructure, and mechanical properties of ZRE1 magnesium (Mg) cast alloy was investigated. The obtained solidification parameters showed that Pr strongly affected the solidification time, leading to refinement of the microstructure of the alloys. When the freezing time was reduced to approximately 52 s, the grain size decreased by 12%. Mg₁₂Zn (Ce,Pr) was formed as a new phase upon the addition of Pr and was detected via X-ray diffraction analysis. The addition of Pr led to a substantial improvement in mechanical properties, which was attributed to the formation of intermetallic compounds; the ultimate tensile strength and yield strength increased by approximately 10% and 13%, respectively. Pr addition also refined the microstructure, and the hardness was recovered. The results herein demonstrate that the mechanical properties of Mg alloys are strongly influenced by their microstructure characteristics, including the grain size, volume fraction, and distribution of intermetallic phases.

研究论文

CuCrW(Al₂O₃) nanocomposite:mechanical alloying, microstructure, and tribological properties

Mohammad Baghani, Mahmood Aliofkhazraei

2017, 24(11): 1321-1334. doi: 10.1007/s12613-017-1524-0

中文摘要(586) PDF(8) SpringerLink

摘要:
The effect of alumina nanoparticle addition on the microstructure and tribological properties of a CuCrW alloy was investigated in this work. Mechanical alloying was carried out in a satellite ball mill. The tribological properties of the samples were evaluated using pin-on-disk wear tests with different pins (alumina, tungsten carbide, and steel pins). The results indicated that the tungsten carbide pin had a lower coefficient of friction than the alumina and steel pins because of its high hardness and low surface roughness. In addition, when the sliding rate was decreased, the weight-loss rate increased. The existence of alumina nanoparticles in the nanocomposite led to a lower weight-loss rate and to a change in the wear mechanism from adhesive to abrasive.

研究论文

Fabrication and properties of aluminum silicate fibrous materials with in situ synthesized K₂Ti₆O₁₃ whiskers

Hao Liu, Nan Wei, Zhou-fu Wang, Xi-tang Wang, Yan Ma

2017, 24(11): 1335-1340. doi: 10.1007/s12613-017-1525-z

中文摘要(415) PDF(11) SpringerLink

摘要:
To improve their mechanical and thermal insulation properties, aluminum silicate fibrous materials with in situ synthesized K₂Ti₆O₁₃ whiskers were prepared by firing a mixture of short aluminum silicate fibers and gel powders obtained from a sol-gel process. During the preparation process, the fiber surface was coated with K₂Ti₆O₁₃ whiskers after the fibers were subjected to a heat treatment carried out at various temperatures. The effects of process parameters on the microstructure, compressive strength, and thermal conductivity were analyzed systematically. The results show that higher treatment temperatures and longer treatment durations promoted the development of K₂Ti₆O₁₃ whiskers on the surface of aluminum silicate fibers; in addition, the intersection structure between whiskers modulated the morphology and volume of the multi-aperture structure among fibers, substantially increasing the fibers' compressive strength and reducing their heat conduction and convective heat transfer at high temperatures.

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2017年第24卷第11期