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Zhang J.,University of Science and Technology Beijing | Zhang J.,Beijing Key Laboratory of Green Recycling and Extraction of Metals | Deng Y.,University of Science and Technology Beijing | Zhou Q.,University of Science and Technology Beijing | And 3 more authors.
Journal of Hazardous Materials | Year: 2017

Separation of vanadium from molybdates is an essential task for processing the leaching solution of hazardous spent hydrodesulphurization (HDS) catalyst. In this study, the difference in the main naturally occurring mineral forms of Mo and V inspired us to develop a method for the deep removal of V from molybdate solution using Fe3O4 as an adsorbent. First, the adsorbent was synthesized with coprecipitation method, and then it was characterized by XRD, TEM, and VSM. The synthesized material consisted of pure Fe3O4 nanoparticles that exhibited paramagnetic property, with a saturated magnetization of 68.6 emu g−1. The V removal efficiency was investigated using batch adsorption experiments in varying conditions. Results indicated that V could be deeply removed from various concentrations of molybdate solution at pH of 7.0–11.0 within 5 min. A slight decrease was found in the adsorption ratio after the adsorbent had been reused for 4 cycles. The resulting molybdate solution contained less than 0.02 g L−1 of V, which satisfies the requirement for preparing high-quality products. Finally, a process flowchart is presented for the separation of Mo and V from the leaching solution of spent HDS catalyst, based on the excellent V removal performance and rapid separation rate of the Fe3O4 adsorbent. © 2017 Elsevier B.V.


Sheng L.,University of Science and Technology Beijing | Li J.-T.,University of Science and Technology Beijing | Li J.-T.,Chambishi Copper Smelter Ltd | Zhang J.-K.,University of Science and Technology Beijing | And 6 more authors.
Gongcheng Kexue Xuebao/Chinese Journal of Engineering | Year: 2017

The viscosity of solid-containing slags can be calculated using the Roscoe equation combined with the calculation functions of multi-component & multi-phase equilibria and pure-liquid slag's viscosity in FactSage software. An FeO-SiO2-Fe3O4-CaO-Al2O3-MgO system used in copper smelting was studied in this paper. Firstly, the parameters of the Roscoe equation were fitted using the measured viscosities of analogous slag in the literature, and the accuracy of viscosity calculated by the method for this slag system was verified additionally. Then, the effect of slag components' contents on the equilibrium phase-composition and viscosity was investigated based on the calculation model. Accordingly, the reasonable proportions of components in the slag were obtained. When the mass fractions of slag components are FeO 40%~60%, SiO2 25%~40%, Fe3O4 0%~15%, CaO 0%~10%, Al2O3 0%~8%, and MgO 0%~4%, the molten slag with good liquidity and fewer solids can be obtained in the smelting process. © All right reserved.


Chai Y.,Beijing Key Laboratory Of Green Recycling and Extraction of Metals | Zhang J.,Beijing Key Laboratory Of Green Recycling and Extraction of Metals
Materials Science and Technology Conference and Exhibition 2014, MS and T 2014 | Year: 2014

For more details about the rule of pulverized coal combustion with CeO2 as its catalyst, this article illustrated the influence of the experiment on anthracite coal combustion under different heating rates(5°C/min, 10°C/min, 15°C/min, 20°C/min) and with different addition of CeO2(0.5%, 1%, 2% respectively) by thermal analysis technique. And a micro analysis of the reaction residue was also made during the process through SEM-EDS. The result showed that (1) CeO2 had a catalytic effect on pulverized coal combustion, thus it was appropriate to be used as combustion adjuvant of blast-injection coal; (2) the higher the heating rate was, the higher the initial combustion temperature of pulverized coal became; (3) CeO2 had different catalytic effects on pulverized coal combustion under different heating rates. To be specific, the catalytic effect could became more remarkable with the increase of heating rate; (4) the increase of CeO2 addition promoted the combustion in a certain range; (5) the catalytic effect would however be limited at a high heating rate. Copyright © 2014 MS&T14®.


Zhang J.,University of Science and Technology Beijing | Zhang J.,Beijing Key Laboratory of Green Recycling and Extraction of Metals | Zhang L.,University of Science and Technology Beijing | Zhang L.,Beijing Key Laboratory of Green Recycling and Extraction of Metals
Xiyou Jinshu/Chinese Journal of Rare Metals | Year: 2016

Aiming at the deep removal of vanadium from molybdates, the thermodynamic equilibrium diagrams were drawn for the distribution of species at different pH and concentrations in Mo(VI)-V(V)-H2O system. The variation regularities were also analyzed. Then the theoretical analysis was conducted for the existing technologies of deep V-removal from molybdates using thermodynamic calculation. The results showed that during the pH-reduction process, VO4 3- firstly polymerized to metavanadate ions, while MoO4 2- polymerized at a lower pH-value which even decreased with the reduction of Mo concentration at the beginning. High concentration of molybdovanadate ions were formed at pH=2.0~5.5. MoO2 2+ and VO2 + were formed in strong acidic solution with low concentration, but V had the stronger ability to transform into cations. According to the theoretical difference, the existing technologies were divided into two types: the first was using the property that V could preferentially polymerise than Mo in weak-alkaline pH range and the second was using the property that V had more tendency to transform into cations. Obviously, the thermodynamic calculation could accurately predict the optimal pH-range for treating feed solution with different concentrations. © Editorial Office of Chinese Journal of Rare Metals. All right reserved.


Li S.-N.,University of Science and Technology Beijing | Ma R.-X.,University of Science and Technology Beijing | Ma R.-X.,Beijing Key Laboratory of Green Recycling and Extraction of Metals | Zhu H.-M.,University of Science and Technology Beijing
Optoelectronics Letters | Year: 2014

Chalcopyrite-type CuInSe2 nanoparticles are successfully prepared by using In2Se3 nanoparticles as a precursor reacted with copper chloride (CuCl) solution via a phase transformation process in low temperature. The reaction time is a key parameter. After the reaction time increasing from 0.5 h to 8 h, In2Se3 and CuCl react with each other gradually via phase transformation into CuInSe2 without any intermediate phase. The crystalline structure and morphology of the CuInSe2 nanoparticles are characterized by X-ray diffraction (XRD) and field emission scanning electron microscopy (FESEM). The diameter of CuInSe2 nanoparticles with good dispersibility ranges from 10 nm to 20 nm. The band gap of the CuInSe2 nanoparticles is 1.04 eV calculated from the ultraviolet-visible (UV-VIS) spectrum. © 2014, Tianjin University of Technology and Springer-Verlag Berlin Heidelberg.


Zhang J.-L.,University of Science and Technology Beijing | Zhang J.-L.,Beijing Key Laboratory of Green Recycling and Extraction of Metals | Hu J.-T.,University of Science and Technology Beijing | Zhang L.-F.,University of Science and Technology Beijing | Zhang L.-F.,Beijing Key Laboratory of Green Recycling and Extraction of Metals
Chinese Journal of Chemical Physics | Year: 2016

Raman spectroscopy was applied to investigate the speciation in both single and mixed solutions of molybdate and vanadate at pH values from 10.0 to 1.0. Evidence was obtained for the difference of existing forms between these two elements. Vanadium mainly exists as (VO3)n n- while Mo is MoO4 2- in the pH range of 9.0-7.5. This difference is the theoretical basis for many available separation process. The species in the binary system was identified by comparing the Raman spectra with that in the single systems. Molybvanadates are formed below pH=6.5, which may partly be ascribed to the replacement of V atoms by Mo atoms in some V-O-V groups. Vanadium mainly exists as the decavanadate species in the pH range of 6.0-2.0. The predominant species of Mo are heteropolyanions having structural features of heptamolybdate rather than Mo8O26 4- and Mo36O112 8- which are the predominant Mo species in single solution at pH=2.0-1.0. © 2016 Chinese Physical Society.


Chen S.,Beijing Key Laboratory of Green Recycling and Extraction of Metals | Chen S.,University of Science and Technology Beijing | Shen S.,Beijing Key Laboratory of Green Recycling and Extraction of Metals | Shen S.,University of Science and Technology Beijing | And 7 more authors.
Hydrometallurgy | Year: 2014

Rh extraction from spent auto-catalysts in an efficient and economical way is still an unresolved problem. In this work, the spent auto-catalyst samples were pretreated with O2, H2 and CO under certain temperatures. After the pretreatments, the samples were leached with acidic sodium chlorate solutions to extract Rh. The Rh extraction for the sample without any pretreatment was 56%. The optimal temperature, time and flow rate of O2 for the O2 pretreatment were 300 C, 3 h and 200 mL/min, respectively, and the Rh extraction under these conditions was 69%. Following O2 pretreatment under optimal condition, H2 or CO pretreatment was also carried out, respectively. The optimal temperature, time and flow rate of H2 for the H2 pretreatment were 300 C, 3 h and 200 mL/min, respectively, and the Rh extraction in this case was 82%. The optimal temperature, time and flow rate of CO for the CO pretreatment were 300 C, 1 h and 150 mL/min, respectively, and the Rh extraction in this case was 80%. In addition, the effects of pretreatment with H2 and CO only on Rh extraction were also studied. It was found that pretreatment with O 2 only was more effective than pretreatment with H2 and CO only, and O2 pretreatment plus a following H2 pretreatment was the most effective means to raise Rh extraction. Additionally, the possible mechanisms involved in pretreatment effects were also investigated. © 2014 Elsevier B.V.


Zhang J.,University of Science and Technology Beijing | Shen S.,Beijing Key Laboratory of Green Recycling and Extraction of Metals | Cheng Y.,University of Science and Technology Beijing | Lan H.,University of Science and Technology Beijing | And 2 more authors.
Hydrometallurgy | Year: 2014

A comprehensive investigation of Au leaching from gold ores with a solution containing thiourea and ammonium thiocyanate was performed. A gold ore A with 18 g/t of Au and 1.15 wt.% of sulfur and another gold ore B with 55.7 g/t of Au and 11.67 wt.% of sulfur were used. The percentages of extracted Au were 57%, 66% and 95% for the leaching solutions containing thiourea only, ammonium thiocyanate only and ammonium thiocyanate plus thiourea, respectively, under optimal conditions. There were some interactions among thiourea, ammonium thiocyanate and ferric ion, which affected gold extraction greatly. The addition of thiocyanate reduced greatly the consumption of thiourea and the process cost accordingly. The optimal concentrations of thiourea, ammonium thiocyanate and ferric sulfate for ore A leaching were 0.13 M, 0.78 M and 0.028 M, respectively. The optimal pH, temperature, time, ratio of liquid to solid, agitation speed and particle size for ore A leaching were 1.5, 21 C, 6 h, 10, 250 rpm and 54-74 μm, respectively. Au extraction for ore A was 95% under above optimal conditions. Au extraction was 97% when sulfur content of ore B was 1.48 wt.%. The preferential consumption of ferric ions by pyrite over by gold was the main reason for resulting in the decrease of gold extraction. Desulfurization is necessary to achieve a high gold extraction for this leaching system of thiourea-thiocynate-Fe3 +. After Au extraction, about 90% of Au was recovered as insoluble metallic Au by cementation using 5 g/L of Al powder. The cementation filtrate was reused to leach Au ore and about 91% of Au was extracted after pH adjustment. Thus, thiocyanate and thiourea could be reused, which reduced the process cost. The leaching speed of Au of this method was more than 4 times faster than that of cyanidation process. This process concerning extraction and recovery of Au from Au ore was effective, fast, environmentally friendly and also likely economical. © 2014 Elsevier B.V.


Xiong L.,Beijing Key Laboratory of Green Recycling and Extraction of Metals | Xiong L.,University of Science and Technology Beijing | Shen S.,Beijing Key Laboratory of Green Recycling and Extraction of Metals | Shen S.,University of Science and Technology Beijing | And 4 more authors.
Industrial and Engineering Chemistry Research | Year: 2014

The reduction of gold ions from HCl-NaClO3 leaching solution with oxalic acid was performed. It was found that, for 50 mL of gold-containing leaching filtrate, 20 mL of 6% (w/v) oxalic acid was required to achieve a selective and effective reduction of gold ions. The reaction temperature and time were found to have significant effects on gold reduction, and the optimal values were determined to be 85 °C and 2 h, respectively. The reduction of gold increased with increasing agitation speed and speed of addition of oxalic acid, and the optimal values were 180 rpm and 1.740 mL/min or more, respectively. Under the optimal conditions, the reductions of Au3+, Cu2+, Fe3+, Pb2+, Ag+, and Si4+ were 95.56%, 0.66%, 2.33%, 1.40%, 0.70%, and 0.50%, respectively. The appropriate solution acidity and solution potential, which are two important conditions for achieving the selective reduction of gold ions, were about 623 mV and 2.3-3.3 M, respectively. © 2014 American Chemical Society.

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