International Journal of Minerals, Metallurgy and Materials

姓名
邮箱
手机号码
标题
留言内容
验证码

Quantitative mineralogical characterization of chrome ore beneficiation plant tailing and its beneficiated products

S. K. Das

2015, 22(4): 335-345. doi: 10.1007/s12613-015-1078-y

中文摘要(385) PDF(30) SpringerLink

摘要:
Mineralogical characterization and liberation of valuable minerals are primary concerns in mineral processing industries. The present investigation focuses on quantitative mineralogy, elemental deportment, and locking-liberation characteristics of the beneficiation of tailings from a chrome ore beneficiation plant in the Sukinda region, Odisha; methods used for the study of the beneficiated tailings are QEMSCAN®, X-ray diffraction (XRD), and mineral chemistry by a scanning electron microscope equipped with an energy-dispersive spectrometer (SEM-EDS). The tailing sample was fine grained (69.48wt% below 45 μm size), containing 20.25wt% Cr₂O₃ and 39.19wt% Fe₂O₃, with a Cr:Fe mass ratio of 0.51. Mineralogical investigations using QEMSCAN studies revealed that chromite, goethite, and gibbsite are the dominant mineral phases with minor amounts of hematite, kaolinite, and quartz. The sample contained 34.22wt% chromite, and chromite liberation is more than 80% for grains smaller than 250 μm in size. Based on these results, it was predicted that liberated chromite and high-grade middling chromite particles could be separated from the gangue by various concentration techniques. The tailing sample was beneficiated by hydrocyclone, tabling, wet high-intensity magnetic separation (WHIMS), and flotation in order to recover the chromite. A chromite concentrate with 45.29wt% Cr₂O₃ and a Cr:Fe mass ratio of 1.85 can be produced from these low-grade chromite ore beneficiation plant rejects.

Roasting-induced phase change and its influence on phosphorus removal through acid leaching for high-phosphorus iron ore

Min Yang, Qing-shan Zhu, Chuan-lin Fan, Zhao-hui Xie, Hong-zhong Li

2015, 22(4): 346-352. doi: 10.1007/s12613-015-1079-x

中文摘要(312) PDF(14) SpringerLink

摘要:
In the present study, roasting-induced phase change and its influence on phosphorus removal via leaching has been investigated for high-phosphorus iron ore. The findings indicate that phosphorus in the ore is associated with goethite and exists mainly in amorphous Fe₃PO₇ phase. The phosphorus remains in the amorphous phase after being roasted below 300℃. Grattarolaite (Fe₃PO₇) is found in samples roasted at 600-700℃, revealing that phosphorus phase is transformed from the amorphous form to crystalline grattarolaite during roasting. Leaching tests on synthesized pure grattarolaite reveal a low rate of phosphorus removal by sulfuric acid leaching. When the roasting temperature is higher than 800℃, grattarolaite is found to react with alumina to form aluminum phosphate, and the reactivity of grattarolaite with alumina increases with increasing roasting temperature. Consequently, the rate of phosphorus removal also increases with increasing roasting temperature due to the formation of acid-soluble aluminum phosphate.

Ultrasound effects on zinc recovery from EAF dust by sulfuric acid leaching

K. Brunelli, M. Dabalà

2015, 22(4): 353-362. doi: 10.1007/s12613-015-1080-4

中文摘要(401) PDF(23) SpringerLink

摘要:
In this work, an ultrasound-assisted leaching process was studied for the recovery of zinc from electric arc furnace (EAF) dust, in which zinc was mainly present in the form of franklinite (60%). Hydrometallurgy is emerging as a preferred process for the recovery of a variety of metals, and the use of ultrasound could offer advantages over the conventional leaching process, especially for the dissolution of franklinite. Franklinite is a refractory phase that is difficult to leach and represents the main obstacle in conventional hydrometallurgy processing. Atmospheric leaching with different sulfuric acid concentrations (0.2-2.0 M) at two temperatures (323 and 353 K) was performed. The tests were conducted using both conventional and ultrasound-assisted leaching. After the leaching tests, the solid residues were characterized by scanning electron microscopy (SEM) and X-ray diffraction (XRD) techniques, whereas the leach liquor was analyzed by inductively coupled plasma spectroscopy (ICP). The use of ultrasound facilitated the dissolution of franklinite at low acid concentrations and resulted in a greater zinc recovery under all of the investigated operating conditions.

Comparison of kinetic models for isothermal CO₂ gasification of coal char-biomass char blended char

Hai-bin Zuo, Wei-wei Geng, Jian-liang Zhang, Guang-wei Wang

2015, 22(4): 363-370. doi: 10.1007/s12613-015-1081-3

中文摘要(342) PDF(17) SpringerLink

摘要:
This study investigated the isothermal gasification reactivity of biomass char (BC) and coal char (CC) blended at mass ratios of 1:3, 1:1, and 3:1 via isothermal thermogravimetric analysis (TGA) at 900, 950, and 1000℃ under CO₂. With an increase in BC blending ratio, there were an increase in gasification rate and a shortening of gasification time. This could be attributed to the high specific surface area of BC and the high uniformity of carbon structures in CC when compared to those in BC. Three representative gas-solid kinetic models, namely, the volumetric model (VM), grain model (GM), and random pore model (RPM), were applied to describe the reaction behavior of the char. Among them, the RPM model was considered the best model to describe the reactivity of the char gasification reaction. The activation energy of BC and CC isothermal gasification as determined using the RPM model was found to be 126.7 kJ/mol and 210.2 kJ/mol, respectively. The activation energy was minimum (123.1 kJ/mol) for the BC blending ratio of 75%. Synergistic effect manifested at all mass ratios of the blended char, which increased with the gasification temperature.

Optimized use of MgO flux in the agglomeration of high-chromium vanadium-titanium magnetite

Jue Tang, Man-sheng Chu, Xiang-xin Xue

2015, 22(4): 371-380. doi: 10.1007/s12613-015-1082-2

中文摘要(338) PDF(12) SpringerLink

摘要:
The optimized use of MgO flux in the agglomeration of high-chromium vanadium-titanium magnetite was investigated systematically through sinter and pellet experiments. MgO was added in the form of magnesite. When the content of MgO in the sinter was increased from 1.95wt% to 2.63wt%, the low-temperature reduction degradation index increased from 80.57% to 82.71%. When the content of MgO in the pellet was increased from 1.14wt% to 2.40wt%, the reduction swelling index decreased from 15.2% to 8.6%; however, the compressive strength of the oxidized pellet decreased dramatically and it was 1985 N with an MgO content of 1.14wt%. This compressive strength does not satisfy the requirements for blast-furnace production. When all of the aforementioned results were taken into account, the sinter with a high MgO content (2.63wt%) matching the pellet with a low MgO content (less than 1.14wt%) was the rational burden structure for smelting high-chromium vanadium-titanium magnetite in blast furnaces.

Reduction and melting behavior of carbon composite lateritic bauxite pellets

Ying-yi Zhang, Jie Zhao, Yuan-hong Qi, Xiang-li Cheng, Zong-shu Zou

2015, 22(4): 381-388. doi: 10.1007/s12613-015-1083-1

中文摘要(270) PDF(8) SpringerLink

摘要:

Direct reduction of low-grade lateritic bauxite was studied at high temperature to recover Fe and beneficiate Al₂O₃ slag. The results show that a metallization rate of 97.9% and a nugget recovery rate of 85.1% can be achieved when the reducing and melting temperatures are 1350 and 1480℃, respectively. Moreover, a higher-grade calcium aluminate slag (Al₂O₃=50.52wt%) can also be obtained, which is mainly composed of α-Al₂O₃, hercynite (FeAl₂O₄), and gehlenite (Ca₂Al₂SiO₇). In addition, high-quality iron nuggets have been produced from low-grade lateritic bauxite. The nugget is mainly composed of iron (93.82wt%) and carbon (3.86wt%), with almost no gangue (slag).

Solid fraction evolution characteristics of semi-solid A356 alloy and in-situ A356-TiB₂ composites investigated by differential thermal analysis

S. Deepak Kumar, A. Mandal, M. Chakraborty

2015, 22(4): 389-394. doi: 10.1007/s12613-015-1084-0

中文摘要(574) PDF(10) SpringerLink

摘要:
The key factor in semi-solid metal processing is the solid fraction at the forming temperature because it affects the microstructure and mechanical properties of the thixoformed components. Though an enormous amount of data exists on the solid fraction-temperature relationship in A356 alloy, information regarding the solid fraction evolution characteristics of A356-TiB₂ composites is scarce. The present article establishes the temperature-solid fraction correlation in A356 alloy and A356-xTiB₂ (x=2.5wt% and 5wt%) composites using differential thermal analysis (DTA). The DTA results indicate that the solidification characteristics of the composites exhibited a variation of 2℃ and 3℃ in liquidus temperatures and a variation of 3℃ and 5℃ in solidus temperatures with respect to the base alloy. Moreover, the eutectic growth temperature and the solid fraction (f_s) vs. temperature characteristics of the composites were found to be higher than those of the base alloy. The investigation revealed that in-situ formed TiB₂ particles in the molten metal introduced more nucleation sites and reduced undercooling.

Effect of equal channel angular extrusion on Al-6063 bending fatigue characteristics

J. Nemati, G. H. Majzoobi, S. Sulaiman, B. T. H. T. Baharudin, M. A. Azmah Hanim

2015, 22(4): 395-404. doi: 10.1007/s12613-015-1085-z

中文摘要(369) PDF(12) SpringerLink

摘要:
The purpose of this investigation was to refine the grains of annealed 6063 aluminum alloy and to improve its yield stress and ultimate strength. This was accomplished via the equal channel angular extrusion (ECAE) process at a temperature of 200℃ using route A, with a constant ram speed of 30 mm/min through a die angle of 90° between the die channels for as many as 6 passes. The experiments were conducted on an Avery universal testing machine. The results showed that the grain diameter decreased from 45 μm to 2.8 μm after 6 extrusion passes. The results also indicated that the major improvement in fatigue resistance occurred after the first pass. The subsequent passes improved the fatigue life but at a considerably lower rate. A maximum increase of 1100% in the case of low applied stresses and an approximately 2200% increase in fatigue resistance in the case of high applied stresses were observed after 5 passes. The improvement of fatigue resistance is presumed to be due to (1) a reduction in the size and the number of Si crystals with increasing number of ECAE passes, (2) the aggregation of Cu during the ECAE process, (3) the formation and growth of CuAl₂ grains, and (4) grain refinement of the Al-6063 alloy during the ECAE process.

Effects of La addition on the microstructure and tensile properties of Al-Si-Cu-Mg casting alloys

Tao Lu, Ye Pan, Ji-li Wu, Shi-wen Tao, Yu Chen

2015, 22(4): 405-410. doi: 10.1007/s12613-015-1086-y

中文摘要(308) PDF(10) SpringerLink

摘要:
The effects of La addition on the microstructure and tensile properties of B-refined and Sr-modified Al-11Si-1.5Cu-0.3Mg casting alloys were investigated. With a trace addition of La (0.05wt%-0.1wt%), the mutual poisoning effect between B and Sr can be neutralized by the formation of LaB₆ rather than SrB₆. By employing a La/B weight ratio of 2:1, uniform microstructures, which are characterized by well refined α-Al grains and adequately modified eutectic Si particles as well as the incorporation of precipitated strengthening intermetallics, are obtained and lead to appreciable tensile properties with an ultimate tensile strength of 270 MPa and elongation of 5.8%.

Microstructure and texture evolution of Mg-3Zn-1Al magnesium alloy during large-strain electroplastic rolling

Yan-bin Jiang, Lei Guan, Guo-yi Tang, Bo Cheng, Da-bo Liu

2015, 22(4): 411-416. doi: 10.1007/s12613-015-1087-x

中文摘要(290) PDF(8) SpringerLink

摘要:
Large-strain deformation by single electroplastic rolling (EPR) was imposed on AZ31 magnesium alloy strips. During EPR at low temperature (150-250℃), numerous twins formed in the alloy. After EPR at a high temperature (350℃), the number of twins reduced and some dynamic recrystallization (DRX) grains formed at grain boundaries and twinned regions. The synergic thermal and athermal effects generated by electropulsing, which promoted dislocation motion, induced a few small DRX grains, and ductile bandings were mainly responsible for large-strain deformation during EPR. The inclination angle of the basal pole stemmed from the counterbalance of the inclination direction of the basal pole between the DRX grains and deformed coarse grains.

Optimal design of sintered Ce₉Nd₂₁Fe_balB₁ magnets with a low-melting-point (Ce,Nd)-rich phase

Shu-lin Huang, Hai-bo Feng, Ming-gang Zhu, An-hua Li, Yan-feng Li, Ya-chao Sun, Yue Zhang, Wei Li

2015, 22(4): 417-422. doi: 10.1007/s12613-015-1088-9

中文摘要(376) PDF(7) SpringerLink

摘要:
A systemic investigation was done on the chemistry and crystal structure of boundary phases in sintered Ce₉Nd₂₁Fe_balB₁ (wt%) magnets. Ce₂Fe₁₄B is believed to be more soluble in the rare-earth (RE)-rich liquid phase during the sintering process. Thus, the grain size and oxygen content were controlled via low-temperature sintering, resulting in high coercivity and maximum energy products. In addition, Ce formed massive agglomerations at the triple-point junctions, as confirmed by elemental mapping results. Transmission electron microscopy (TEM) images indicated the presence of (Ce,Nd)O_x phases at grain boundaries. By controlling the composition and optimizing the preparation process, we successfully obtained Ce₉Nd₂₁Fe_balB₁ sintered magnets; the prepared magnets exhibited a residual induction, coercivity, and energy product of 1.353 T, 759 kA/m, and 342 kJ/m³, respectively.

Effect of CeH_2.29 on the microstructures and hydrogen properties of LiBH₄-Mg₂NiH₄ composites

Xin Zhao, Shu-min Han, Yuan Li, Xiao-cui Chen, Dan-dan Ke

2015, 22(4): 423-428. doi: 10.1007/s12613-015-1089-8

中文摘要(274) PDF(7) SpringerLink

摘要:
A composite of LiBH₄-Mg₂NiH₄ doped with 10wt% CeH_2.29 was prepared by ball milling followed by dynamic interspace vacuum treatment at 573 K. The introduction of CeH_2.29 caused a transformation in the morphology of Mg from complex spongy and lamellar to uniformly spongy, resulting in refined particle size and abundant H diffusion pathways. This LiBH₄-Mg₂NiH₄ + 10wt% CeH_2.29 composite exhibited excellent hydrogen storage properties. The starting temperature of rapid H absorption decreased to 375 K in the doped composite from 452 K for the unmodified material, and the onset decomposition temperature of its hydride was reduced from 536 K to 517 K. In addition, the time required for a hydrogen release of 1.5wt% (at 598 K) was 87 s less than that of the un-doped composite.

Extraction and characterization of alumina nanopowders from aluminum dross by acid dissolution process

Md. Saifur Rahman Sarker, Md. Zahangir Alam, Md. Rakibul Qadir, M A Gafur, Mohammad Moniruzzaman

2015, 22(4): 429-436. doi: 10.1007/s12613-015-1090-2

中文摘要(386) PDF(20) SpringerLink

摘要:
A significant amount of aluminum dross is available as a waste in foundry industries in Bangladesh. In this study, alumina was extracted from aluminum dross collected from two foundry industries situated in Dhamrai and Manikgang, near the capital city, Dhaka. Aluminum dross samples were found to approximately contain 75wt% Al₂O₃ and 12wt% SiO₂. An acid dissolution process was used to recover the alumina value from the dross. The effects of various parameters, e.g., temperature, acid concentration, and leaching time, on the extraction of alumina were studied to optimize the dissolution process. First, Al(OH)₃ was produced in the form of a gel. Calcination of the Al(OH)₃ gel at 1000℃, 1200℃, and 1400℃ for 2 h produced θ-Al₂O₃, (α+θ)-Al₂O₃, and α-alumina powder, respectively. Thermal characterization of the Al(OH)₃ gel was performed by thermogravimetric/differential thermal analysis (TG/DTA) and differential scanning calorimetry (DSC). The phases and crystallite size of the alumina were determined by X-ray diffraction analysis. The dimensions of the alumina were found to be on the nano level. The chemical compositions of the aluminum dross and alumina were determined by X-ray fluorescence (XRF) spectroscopy. The microstructure and morphology of the alumina were studied with scanning electron microscopy. The purity of the alumina extracted in this study was found to be 99.0%. Thus, it is expected that the obtained alumina powders can be potentially utilized as biomaterials.

Preparation of a novel PAN/cellulose acetate-Ag based activated carbon nanofiber and its adsorption performance for low-concentration SO₂

Yan-bo Wu, Jun Bi, Ting Lou, Tie-ben Song, Hong-quan Yu

2015, 22(4): 437-445. doi: 10.1007/s12613-015-1091-1

中文摘要(388) PDF(32) SpringerLink

摘要:
Polyacrylonitrile (PAN), PAN/cellulose acetate (CA), and PAN/CA-Ag based activated carbon nanofiber (ACNF) were prepared using electrostatic spinning and further heat treatment. Thermogravimetry-differential scanning calorimetry (TG-DSC) analysis indicated that the addition of CA or Ag did not have a significant impact on the thermal decomposition of PAN materials but the yields of fibers could be improved. Scanning electron microscopy (SEM) analysis showed that the micromorphologies of produced fibers were greatly influenced by the viscosity and conductivity of precursor solutions. Fourier transform infrared spectroscopy (FT-IR) analysis proved that a cyclized or trapezoidal structure could form and the carbon scaffold composed of C=C bonds appeared in the PAN-based ACNFs. The characteristic diffraction peaks in X-ray diffraction (XRD) spectra were the evidence of a turbostratic structure and silver existed in the PAN/CA-Ag based ACNF. Brunner-Emmett-Teller (BET) analysis showed that the doping of CA and Ag increased surface area and micropore volume of fibers; particularly, PAN/CA-Ag based ACNF exhibited the best porosity feature. Furthermore, SO₂ adsorption experiments indicated that all the three fibers had good adsorption effects on lower concentrations of SO₂ at room temperature; especially, the PAN/CA-Ag based ACNF showed the best adsorption performance, and it may be one of the most promising adsorbents used in the fields of chemical industry and environment protection.

留言板

2015年第22卷第4期

视频展示更多>

期刊特色

期刊荣誉更多>

友情链接更多>

留言板

2015年 第22卷 第4期

视频展示更多>

期刊特色

期刊荣誉更多>

友情链接更多>

2015年第22卷第4期