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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. Source


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. Source


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®. Source


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. Source


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. Source

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