International Journal of Minerals, Metallurgy and Materials

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Hydrometallurgical application for treating a Nigerian chalcopyrite ore in chloride medium: Part I. Dissolution kinetics assessment

Alafara A. Baba, Kuranga I. Ayinla, Folahan A. Adekola, Rafiu B. Bale, Malay K. Ghosh, Abdul G. F. Alabi, Abdul R. Sheik, Ismael O. Folorunso

2013, 20(11): 1021-1028. doi: 10.1007/s12613-013-0829-x

中文摘要(230) PDF(12) SpringerLink

摘要:
The dissolution kinetics of a Nigerian chalcopyrite ore in hydrochloric acid was studied in this article. Acid concentration, reaction temperature, and ore particle size were chosen as experimental parameters. The chemical and morphological studies of the ore before and after leaching at optimal conditions were carried out by X-ray diffraction (XRD) and scanning electron microscopy (SEM). It is revealed that increasing the acid concentration and system temperature and decreasing the ore particle size greatly enhances the dissolution rate. The dissolution kinetics was found to follow the shrinking core model for the diffusion control mechanism where the activation energy (E_a) of 32.92 kJ·mol⁻¹ was obtained for the process and supported by morphological changes at a higher dissolution of 91.33%.

Nickel solvent extraction from cold purification filter cakes of Angouran mine concentrate using LIX984N

A. A. Balesini, A. Zakeri, H. Razavizadeh, A. Khani

2013, 20(11): 1029-1034. doi: 10.1007/s12613-013-0830-4

中文摘要(282) PDF(16) SpringerLink

摘要:
Cold purification filter cakes generated in the hydrometallurgical processing of Angouran mine zinc concentrate commonly contain significant amounts of Zn, Cd, and Ni ions and thus are valuable resources for metal recovery. In this research, a nickel containing solution that was obtained from sulfuric acid leaching of the filter cake following cadmium and zinc removal was subjected to solvent extraction experiments using 10vol% LIX984N diluted in kerosene. Under optimum experimental conditions (pH 5.3, volume ratio of organic/aqueous (O:A) = 2:1, and contact time = 5 min), more than 97.1% of nickel was extracted. Nickel was stripped from the loaded organic by contacting with a 200 g/L sulfuric acid solution, from which 77.7% of nickel was recovered in a single contact at the optimum conditions (pH 1–1.5, O:A = 5:1, and contact time = 15 min).

Recovery of iron from copper slag by deep reduction and magnetic beneficiation

Ke-qing Li, Shuo Ping, Hong-yu Wang, Wen Ni

2013, 20(11): 1035-1041. doi: 10.1007/s12613-013-0831-3

中文摘要(208) PDF(10) SpringerLink

摘要:
Aiming at recovering iron from high-iron-content copper slag, this article introduced a combination technology of deep reduction and magnetic beneficiation, investigated the iron recovery efficiency and optimized the technical conditions. When coke powder with 86wt% fixed carbon was used as a reductant, iron was successfully extracted from the copper slag. Under the optimized condition of the coke powder content of 14wt%, the calcium-to-silicon mass ratio (Ca/Si) of 0.2, the roasting temperature of 1300℃, the roasting time of 3 h, the grinding time of 20 min, and the magnetic field intensity of 61 kA·m⁻¹, the iron recovery rate of the copper slag can reach 91.82%, and the extracted iron powder has an iron grade of 96.21%. With the characteristics of high iron grade and low impurity content, the extracted iron powder can be used as high-quality raw materials of weathering steel.

Mathematical simulation of direct reduction process in zinc-bearing pellets

Ying Liu, Fu-yong Su, Zhi Wen, Zhi Li, Hai-quan Yong, Xiao-hong Feng

2013, 20(11): 1042-1049. doi: 10.1007/s12613-013-0832-2

中文摘要(234) PDF(12) SpringerLink

摘要:
A one-dimensional unsteady mathematical model was established to describe direct reduction in a composite pellet made of metallurgical dust. The model considered heat transfer, mass transfer, and chemical reactions including iron oxide reductions, zinc oxide reduction and carbon gasification, and it was numerically solved by the tridiagonal matrix algorithm (TDMA). In order to verify the model, an experiment was performed, in which the profiles of temperature and zinc removal rate were measured during the reduction process. Results calculated by the mathematical model were in fairly good agreement with experimental data. Finally, the effects of furnace temperature, pellet size, and carbon content were investigated by model calculations. It is found that the pellet temperature curve can be divided into four parts according to heating rate. Also, the zinc removal rate increases with the increase of furnace temperature and the decrease of pellet size, and carbon content in the pellet has little influence on the zinc removal rate.

Element distribution and diffusion behavior in Q&P steel during partitioning

Hai-tao Jiang, Bao-tong Zhuang, Xiao-ge Duan, Yan-xin Wu, Zheng-xu Cai

2013, 20(11): 1050-1059. doi: 10.1007/s12613-013-0833-1

中文摘要(228) PDF(9) SpringerLink

摘要:
Carbon, manganese, and silicon distribution in quenching and partitioning (Q&P) steel during partitioning process was investigated to reveal the diffusion behavior. The microstructure and chemical composition were analyzed by means of scanning electron microscopy (SEM), transmission electron microscopy (TEM), and three-dimensional atom probe. It is shown that the studied Q&P steel consisted of martensite laths and thin, film-like retained austenite showing extraordinary phase transformation stability. Carbon atoms mostly diffused to the retained austenite from martensite at a higher partitioning temperature. In the experimental steel partitioned at 400℃ for 10–60 s, carbides or cementite formed through carbon segregation along martensite boundaries or within the martensite matrix. As a result of carbon atom diffusion from martensite to austenite, the carbon content in martensite could be ignored. When the partitioning process completed, the constrained carbon equilibrium (CCE) could be simplified. Results calculated by the simplified CCE model were similar to those of CCE, and the difference between the two optimum quenching temperatures, where the maximum volume fraction of the retained austenite can be obtained by the Q&P process, was little.

In situ observations of austenite grain growth in Fe-C-Mn-Si super bainitic steel

Feng Liu, Guang Xu, Yu-long Zhang, Hai-jiang Hu, Lin-xin Zhou, Zheng-liang Xue

2013, 20(11): 1060-1066. doi: 10.1007/s12613-013-0834-0

中文摘要(176) PDF(8) SpringerLink

摘要:
In situ observations of austenite grain growth in Fe-C-Mn-Si super bainitic steel were conducted on a high-temperature laser scanning confocal microscope during continuous heating and subsequent isothermal holding at 850, 1000, and 1100℃ for 30 min. A grain growth model was proposed based on experimental results. It is indicated that the austenite grain size increases with austenitizing temperature and holding time. When the austenitizing temperature is above 1100℃, the austenite grains grow rapidly, and abnormal austenite grains occur. In addition, the effect of heating rate on austenite grain growth was investigated, and the relation between austenite grains and bainite morphology after bainitic transformations was also discussed.

Effects of thermal aging temperature and Cr content on phase separation kinetics in Fe-Cr alloys simulated by the phase field method

Shu-xiao Li, Hai-long Zhang, Shi-lei Li, Yan-li Wang, Fei Xue, Xi-tao Wang

2013, 20(11): 1067-1075. doi: 10.1007/s12613-013-0835-z

中文摘要(151) PDF(7) SpringerLink

摘要:
Phase field simulations of phase separation in Fe-Cr binary alloys were performed by using the Cahn-Hilliard diffusion function. A new mobility model in relation to aging temperature and Cr content was used in the simulations. Two alloys of Fe-30at%Cr and Fe-35at%Cr were investigated at two different aging temperatures of 573 and 673 K. The phase separation kinetics was found to consist of three stages: wavelength modulation, amplitude increase, and coarsening of Cr-enriched regions. A higher thermal aging temperature accelerated the phase separation and increased the wavelength of concentration fluctuation. While the effect of Cr content on the phase separation kinetics was slight, Fe-Cr alloys with a higher Cr content were found to generate a larger number and a finer size of Cr-enriched regions. The simulation results provide consultation for design and safe operation of duplex stainless steel pipes in nuclear power plants.

Near-net shape processing of spherical high Nb-TiAl alloy powder by gelcasting

Hui-ping Shao, Xiao-ting Liu, Ye Ji, Zhi-meng Guo

2013, 20(11): 1076-1080. doi: 10.1007/s12613-013-0836-y

中文摘要(170) PDF(8) SpringerLink

摘要:
Spherical Ti-45Al-8.5Nb-(W,B,Y) alloy powder prepared by an argon plasma process was near-net shape by gelcasting. In the non-aqueous system, methaerylate-2-hydroxy ethyl, toluene, benzoyl peroxide, and N,N-dimethylaniline were used as the monomer, solvent, initiator, and catalyst, respectively. To improve sintering and forming behaviors, many additives were included in the suspension. The concentrated suspension with a solid loading of 70vol% was prepared. The high Nb-TiAl powder was analyzed by electron microscopy and X-ray diffraction. It was found that the green bodies had a smooth surface and homogeneous microstructure, exhibiting a bending strength as high as 50 MPa. After sintering at 1480℃ for 2 h in vacuum, uniform complex-shaped high Nb-TiAl parts were successfully produced.

Production and characterization of hydrophobic zinc borate by using palm oil

Nil Baran Acarali, Nurcan Tugrul, Emek Moroydor Derun, Sabriye Piskin

2013, 20(11): 1081-1088. doi: 10.1007/s12613-013-0837-x

中文摘要(194) PDF(7) SpringerLink

摘要:
Zinc borate (ZB) was synthesized using zinc oxide, boric acid synthesized from colemanite, and reference ZB as seed. The effects of reaction parameters such as reaction time, reactant ratio, and seed ratio on its yield were examined. Then, the effects of palm oil with solvents (isopropyl alcohol (IPA), ethanol, and methanol) added to the reaction on its hydrophobicity were explored. Reactions were carried out under determined reaction conditions with magnetically and mechanically stirred systems. The produced ZB was characterized by X-ray diffraction (XRD), Fourier transform infrared spectroscopy (FT-IR), scanning electron microscopy (SEM), and measurements of contact angle identified hydrophobicity. The results showed that hydrophobic ZB was successfully produced under determined reaction conditions. The change of process parameters influenced its yield and the usage of palm oil provided hydrophobicity.

Effect of light response on the photocatalytic activity of BiOCl_xBr_1−x in the removal of Rhodamine B from water

Xiao-ming Mao, Cai-mei Fan

2013, 20(11): 1089-1096. doi: 10.1007/s12613-013-0838-9

中文摘要(193) PDF(7) SpringerLink

摘要:
BiOCl_xBr_1−x catalysts were synthesized through an alcoholysis method and characterized by X-ray diffraction (XRD), transmission electron microscopy (TEM), high-resolution transmission electron microscopy (HRTEM), and diffuse reflectance spectroscopy (DRS). The as-prepared photocatalysts were found to be tetragonal crystal structure and lamellar plate morphology. Their band gaps were between 3.44 and 2.83 eV. The effect of light response on the photocatalytic activity of BiOCl_xBr_1−x was investigated by degradation of Rhodamine B (RhB). Complete removal of RhB from water was realized under simulated sunlight irradiation for 50 min with BiOCl_0.5Br_0.5. Mechanism studies showed that photogenerated holes and superoxide anion radicals played important roles in RhB photodegradation. The results of chemical oxygen demand (COD) confirmed RhB mineralization. The effect of light response on the activity of BiOCl_xBr_1−x was further investigated under monochromatic light irradiation, and BiOCl_0.5Br_0.5 catalyst exhibited the highest activity. Furthermore, BiOCl_0.5Br_0.5 exhibited high stability, suggesting its practical application for the removal of RhB pollutant from water.

Synthesis and characterization of boron-doped NiO thin films produced by spray pyrolysis

U. Alver, H. Yaykaşlı, S. Kerli, A. Tanrıverdi

2013, 20(11): 1097-1101. doi: 10.1007/s12613-013-0839-8

中文摘要(194) PDF(16) SpringerLink

摘要:
Boron-doped NiO thin films were prepared on glass substrates at 400℃ by airbrush spraying method using a solution of nickel nitrate hexahydrate. Their physical properties were investigated as a function of dopant concentration. From X-ray diffraction patterns, it is observed that the films have cubic structure with lattice parameters varying with boron concentration. The morphologies of the films were examined by using scanning electron microscopy, and the grain sizes were measured to be around 30–50 nm. Optical measurements show that the band gap energies of the films first decrease then increase with increasing boron concentration. The resistivities of the films were determined by four point probe method, and the changes in resistivity with boron concentration were investigated.

Preparation of metal oxide doped ACNFs and their adsorption performance for low concentration SO₂

Hong-quan Yu, Yan-bo Wu, Tie-ben Song, Yue Li, Yu Shen

2013, 20(11): 1102-1106. doi: 10.1007/s12613-013-0840-2

中文摘要(251) PDF(7) SpringerLink

摘要:
Metal oxide (TiO₂ or Co₃O₄) doped activated carbon nanofibers (ACNFs) were prepared by electrospinning. These nanofibers were characterized by X-ray diffraction (XRD), scanning electron microscopy (SEM), and Brunner-Emmett-Teller method (BET). The results show that the average diameters of ACNFs were within the range of 200–500 nm, and the lengths were several tens of micrometers. The specific surface areas were 1146.7 m²/g for TiO₂-doped ACNFs and 1238.5 m²/g for Co₃O₄-doped ACNFs, respectively. The electrospun nanofibers were used for adsorption of low concentration sulfur dioxide (SO₂). The results showed that the adsorption rates of these ACNFs increased with an increase in SO₂ concentration. When the SO₂ concentration was 1.0 μg/mL, the adsorption rates of TiO₂-doped ACNFs and Co₃O₄-doped ACNFs were 66.2% and 67.1%, respectively. The adsorption rate also increased as the adsorption time increased. When the adsorption time was 40 min, the adsorption rates were 67.6% and 69.0% for TiO₂-doped ACNFs and Co₃O₄-doped ACNFs, respectively. The adsorption rate decreased as the adsorption temperature increased below 60℃, while it increased as the adsorption temperature increased to more than 60℃.

Rapid synthesis of MoSi₂-Si₃N₄ nanocomposite via reaction milling of Si and Mo powder mixture

Majid Abdellahi, Alireza Amereh, Hamed Bahmanpou, Behzad Sharafati

2013, 20(11): 1107-1114. doi: 10.1007/s12613-013-0841-1

中文摘要(178) PDF(7) SpringerLink

摘要:
The nanocomposite of MoSi₂-Si₃N₄ (molybdenum disilicide-silicon nitride) was synthesized by reaction milling of the Mo and Si powder mixture. Changing the processing parameters led to the formation of different products such as α- and β-MoSi₂, Si₃N₄, Mo₂N, and Mo₅Si₃ at various milling times. A thermodynamic appraisal showed that the milling of Mo₃₂Si₆₈ powder mixture was associated with highly exothermic mechanically induced self-sustaining reaction (MSR) between Mo and Si. The MSR took place around 5 h of milling led to the formation of α-MoSi₂ and the reaction between Si and N₂ to produce Si₃N₄ under a nitrogen pressure of 1 MPa. By increasing the nitrogen pressure to 5 MPa, more heat is released, resulting in the dissociation of Si₃N₄ and the transformation of α-MoSi₂ to β-MoSi₂. Heat treatment was also performed on the milled samples and led to the formation of Mo₂N and the transformation of α-MoSi₂ to β-MoSi₂ at the milling times of 10 and 40 h, respectively.

Microstructure and properties of nano-TiN modified Ti(C,N)-based cermets fabricated by powder injection molding and die pressing

Shan-jie Yi, Hai-qing Yin, Ke Chen, Dil-Faraz Khan, Qing-jun Zheng, Xuan-hui Qu

2013, 20(11): 1115-1121. doi: 10.1007/s12613-013-0842-0

中文摘要(213) PDF(7) SpringerLink

摘要:
Powder injection molding (PIM) and die pressing were employed to fabricate nano-TiN modified Ti(C,N)-based cermets. The shrinkage behavior, microstructure, porosity, and mechanical properties of the samples with and without nano-TiN addition fabricated by PIM and die pressing were analyzed. It is demonstrated that for either PIM or die pressing, the porosities are obviously reduced, the mechanical properties are significantly improved after adding nano-TiN, and the hard particles are refined; the rim phase thickness obviously becomes thinner, and the number of dimples in fracture also increases. Compared the samples fabricated by die pressing, it is difficult for PIM to obtain dense Ti(C,N)-based cermets. Due to the too much existence of pores and isolated carbon, the mechanical properties of the sintered samples by PIM are inferior to those of the sintered ones by die pressing.

Erratum to: Mathematical model of burden distribution for the bell-less top of a blast furnace

Zhao-jie Teng, Shu-sen Cheng, Peng-yu Du, Xi-bin Guo

2013, 20(11): 1122-1122. doi: 10.1007/s12613-013-0843-z

中文摘要(129) PDF(12) SpringerLink

摘要: