A new technology of one-step leaching of refractory gold concentrate containing arsenic and sulfur was studied and 96. 8% of gold was extracted in an hour by this technology. Themodynamic possibility of reactions of a...A new technology of one-step leaching of refractory gold concentrate containing arsenic and sulfur was studied and 96. 8% of gold was extracted in an hour by this technology. Themodynamic possibility of reactions of arsenopyrite. pyrite and gold with sodium hypochlorite in NaOH medium, and solution chemistry of H3AuO3 at different pH values were analyzed. The reason why the gold wrapped by FeAsS, FeS2 can be leached out rapidly by grnding of porcelain ball mill. is explained.展开更多
Na2SiO3 and Na2SeO3 were chosen as stable reagents of alkaline thiourea solution substituting Na2SO3, according to the structure-property relationship between the stability of alkaline thiourea and the structure of th...Na2SiO3 and Na2SeO3 were chosen as stable reagents of alkaline thiourea solution substituting Na2SO3, according to the structure-property relationship between the stability of alkaline thiourea and the structure of thiourea and sulfite ion, and the effect of the stable reagents on stability of alkaline thiourea was investigated. The results show that contrary to Na2SeO3, Na2SO3 and Na2SiO3 affect the stability of alkaline thiourea solution remarkably. The stable effect of Na2SiO3 on alkaline thiourea is obviously better than that of Na2SO3. The stable reagents Na2SO3 and Na2SiO3 decrease the decomposition rate of alkaline thiourea solution greatly, and the decomposition rate of alkaline thiourea reduces from （72.5%） to （33.8%） with addition of (0.3 mol·L-1) Na2SiO3. Dissolution currents of gold in the alkaline thiourea solution containing Na2SO3 and Na2SiO3 are （2.0） (mA·cm-2) and （3.5） (mA·cm-2) at the potential of 0.42 V, respectively, and Na2SO3 is consumed excessively due to the oxidation reaction of Na2SO3 occurring in the studied potential range. Na2SiO3 is an efficient stable reagent of alkaline thiourea solution, and gold dissolution is accelerated much more obviously by Na2SiO3 than by Na2SO3.展开更多
For the high sulfur refractory gold concentrate with 41.82%sulfur and 15.12 g/t gold,of which 82.11%was wrapped in sulfide,a well-controlled stirring tank leaching was carried out to improve the bio-oxidation efficien...For the high sulfur refractory gold concentrate with 41.82%sulfur and 15.12 g/t gold,of which 82.11%was wrapped in sulfide,a well-controlled stirring tank leaching was carried out to improve the bio-oxidation efficiency.Results show that bio-oxidation pretreatment can greatly improve the gold recovery rate of high-sulfur refractory gold concentrate,and at the optimum pH 1.3 in this study,compared with the process without pH control,the oxidation rate of sulfur increased from 79.31%to 83.29%,while the recovery rate of gold increased from 76.54%to 83.23%;under this condition the activity of mixed culture could be sustained and the formation of jarosite could diminish.The results also displayed that for the high sulfur refractory gold concentrate,the recovery of gold is positively correlated with the oxidation rate of sulfur,and the recovery rate of gold increases with the increase of sulfur oxidation rate within a certain range.展开更多
The linear potential sweep voltammetry and electrochemical methods were used to study the mechanism and kinetics of gold dissolution in thiourea solution in the absence and presence of sodium sulphite.The results show...The linear potential sweep voltammetry and electrochemical methods were used to study the mechanism and kinetics of gold dissolution in thiourea solution in the absence and presence of sodium sulphite.The results show that in the absence of sodium sulfite the dissolution rate of gold in thiourea solution is relatively slow and it increases with the increase of the concentration of thiourea and decreases with pH. Thiourea is easily oxidized to formamidine disulphide, which reduces the leaching efficiency and increases reagent consumption. In the presence of sodium sulphite, the effective concentration of thiourea is increased and the dissolution rate of gold in thiourea solution is greatly increased. The activation energy required for gold dissolution in thiourea solution with sodium sulphite is 20.9 kJ·mol -1 which is much lower than 55.0 kJ·mol -1 in the absence of sodium sulphite. It is evident that sodium sulphite has a significant effect on the electrochemical reaction kinetics of gold in thiourea solution.展开更多
The paper thermodynamically examined the behavior of various copper minerals in cyanide solu tions and investigated the influence of copper minerals on cyanide leaching of gold. In elucidating the influence of copper ...The paper thermodynamically examined the behavior of various copper minerals in cyanide solu tions and investigated the influence of copper minerals on cyanide leaching of gold. In elucidating the influence of copper minerals on cyanide leaching of gold, copper minerals were classified into two types according to their solubility in cyanide solutions by proposing two concepts, cyaniding easily soluble copper (E Cu ) and cyaniding insoluble copper. The former involves copper occurrence in metal, oxides and secondary sulfides, and the latter refers mainly to primary sulfides. Experimental results show that not all the total copper in an ore affected cyanide leaching of gold, while cyaniding easily soluble copper turns out to be the decisive factor that interferes with gold cyanidation by causing decrease in gold cyanidation recovery and increase in cyanide consumption. When cyaniding easily soluble copper content ( w E(Cu) ) lies in the range of 0 0.25%, it linearly affects gold cyanidation recovery ( R ) as well as cyanide consumption ( m c). The regression equations have been worked out to be R (%)=94.177 5-142.735 7 w E(Cu) with a correlation coefficient of -0.902 and m c=5.590 7+33.572 9 w E(Cu) with a correlation coefficient of 0.945, respectively.展开更多
The regularities of anodic oxidation of thiosulfate ions on a gold electrode have been investigated using electrochemical methods in order to improve gold extraction. Effects of ammon, copper-ammon ions, pH and sulphi...The regularities of anodic oxidation of thiosulfate ions on a gold electrode have been investigated using electrochemical methods in order to improve gold extraction. Effects of ammon, copper-ammon ions, pH and sulphite on anodic oxidation of thiosulfate ions have been examined in details. Results show that the anodic oxidation of thiosulfate ions is an inreversible reaction whose oxidizing peak potential is 620 mV/SCE in the absence of ammon. Oxidation rate increases with concentration of thiosulfate ions, but not in linear relation. It is also shown that ammon has significant effects on the oxidation of thiosulfate ions by causing great decrease in oxidation rate and negative shift of peak potential. The degrees of the rate decrease and negative shift increase with ammon concentration. When ammon concentration is increased to 1. 0 mol/L, the oxidation rate decreases to one fourth of that without ammon and the peak potential shifts from 620 mV/SCE to 350 mV/SCE.展开更多
Heap leaching is a promising, less costly, alternative technology for processing low grade gold ores compared with traditional, energy intensive processes (e.g. autoclave/tank leaching). This research investigated the...Heap leaching is a promising, less costly, alternative technology for processing low grade gold ores compared with traditional, energy intensive processes (e.g. autoclave/tank leaching). This research investigated the effectiveness of lime for enhancing gold leaching rates of gold ores from ajialongwa gold mine in china. Column and heaping experiments were performed using cyanide leaching solutions at pH=10, with and without lime (CaO). The presence of lime greatly increased gold leaching rates. Column leaching experiments showed without the addition of lime, there was 35.2% of gold leached. The addition of lime resulted in the release of 50.56% gold. Lime assisted cyanide of refractory gold was proved by heap leaching experiments.展开更多
The ultra fine grinding and resin in pulp with pH value of 10 are used to extract gold from pyrite roster cinder. During leaching process, aluminium oxide ball is used as stirring medium, hydrogen peroxide as leaching...The ultra fine grinding and resin in pulp with pH value of 10 are used to extract gold from pyrite roster cinder. During leaching process, aluminium oxide ball is used as stirring medium, hydrogen peroxide as leaching agent and sodium hexametaphosphate as grinding agent. With AM 2б resin as absorber and sulfocarbamide as eluent, gold is recovered from cyanide pulp of pyrite roster cinder by resin in pulp. The effects of contact time, temperature and acidity etc. on the gold absorption are investigated by static methods and dynamic method respectively. The effects of flow rate of solution on dynamic adsorption and elution of gold are studied. The results show that AM 2б resin has good adsorbability in cyanide solution, and gold can be easily eluated from the loaded resin with 0.1mol/L hydrochloric acid and 1mol/L sulfocabamide. The adsorption rate and the elution of gold exceed 98%. When leaching time is 2 h, mass ratio of liquid to solid 4∶1, consumption of sodium cyanide 3 kg/t, concentration of hydrogen peroxide and sodium hexametaphosphate 0.05% respectively, adsorption time 30 min, temperature 10 30 ℃, volume of resin 3 mL, ratio of eluent to resin (10 20)∶1, velocity of eluent 1.5 mL/min, the leaching rate of gold reaches 85%. Compared with traditional leaching technology, it can reduce leaching time, avoid complex filter process, decrease sodium cyanide consumption and increase leaching rate of gold by 35%.展开更多
文摘A new technology of one-step leaching of refractory gold concentrate containing arsenic and sulfur was studied and 96. 8% of gold was extracted in an hour by this technology. Themodynamic possibility of reactions of arsenopyrite. pyrite and gold with sodium hypochlorite in NaOH medium, and solution chemistry of H3AuO3 at different pH values were analyzed. The reason why the gold wrapped by FeAsS, FeS2 can be leached out rapidly by grnding of porcelain ball mill. is explained.
文摘Na2SiO3 and Na2SeO3 were chosen as stable reagents of alkaline thiourea solution substituting Na2SO3, according to the structure-property relationship between the stability of alkaline thiourea and the structure of thiourea and sulfite ion, and the effect of the stable reagents on stability of alkaline thiourea was investigated. The results show that contrary to Na2SeO3, Na2SO3 and Na2SiO3 affect the stability of alkaline thiourea solution remarkably. The stable effect of Na2SiO3 on alkaline thiourea is obviously better than that of Na2SO3. The stable reagents Na2SO3 and Na2SiO3 decrease the decomposition rate of alkaline thiourea solution greatly, and the decomposition rate of alkaline thiourea reduces from （72.5%） to （33.8%） with addition of (0.3 mol·L-1) Na2SiO3. Dissolution currents of gold in the alkaline thiourea solution containing Na2SO3 and Na2SiO3 are （2.0） (mA·cm-2) and （3.5） (mA·cm-2) at the potential of 0.42 V, respectively, and Na2SO3 is consumed excessively due to the oxidation reaction of Na2SO3 occurring in the studied potential range. Na2SiO3 is an efficient stable reagent of alkaline thiourea solution, and gold dissolution is accelerated much more obviously by Na2SiO3 than by Na2SO3.
基金Projects(51704028,51574036)supported by the National Natural Science Foundation of ChinaProject supported by Program for Key Laboratory of Biohydrometallurgy of Ministry of Education Foundation,China。
文摘For the high sulfur refractory gold concentrate with 41.82%sulfur and 15.12 g/t gold,of which 82.11%was wrapped in sulfide,a well-controlled stirring tank leaching was carried out to improve the bio-oxidation efficiency.Results show that bio-oxidation pretreatment can greatly improve the gold recovery rate of high-sulfur refractory gold concentrate,and at the optimum pH 1.3 in this study,compared with the process without pH control,the oxidation rate of sulfur increased from 79.31%to 83.29%,while the recovery rate of gold increased from 76.54%to 83.23%;under this condition the activity of mixed culture could be sustained and the formation of jarosite could diminish.The results also displayed that for the high sulfur refractory gold concentrate,the recovery of gold is positively correlated with the oxidation rate of sulfur,and the recovery rate of gold increases with the increase of sulfur oxidation rate within a certain range.
文摘The linear potential sweep voltammetry and electrochemical methods were used to study the mechanism and kinetics of gold dissolution in thiourea solution in the absence and presence of sodium sulphite.The results show that in the absence of sodium sulfite the dissolution rate of gold in thiourea solution is relatively slow and it increases with the increase of the concentration of thiourea and decreases with pH. Thiourea is easily oxidized to formamidine disulphide, which reduces the leaching efficiency and increases reagent consumption. In the presence of sodium sulphite, the effective concentration of thiourea is increased and the dissolution rate of gold in thiourea solution is greatly increased. The activation energy required for gold dissolution in thiourea solution with sodium sulphite is 20.9 kJ·mol -1 which is much lower than 55.0 kJ·mol -1 in the absence of sodium sulphite. It is evident that sodium sulphite has a significant effect on the electrochemical reaction kinetics of gold in thiourea solution.
文摘The paper thermodynamically examined the behavior of various copper minerals in cyanide solu tions and investigated the influence of copper minerals on cyanide leaching of gold. In elucidating the influence of copper minerals on cyanide leaching of gold, copper minerals were classified into two types according to their solubility in cyanide solutions by proposing two concepts, cyaniding easily soluble copper (E Cu ) and cyaniding insoluble copper. The former involves copper occurrence in metal, oxides and secondary sulfides, and the latter refers mainly to primary sulfides. Experimental results show that not all the total copper in an ore affected cyanide leaching of gold, while cyaniding easily soluble copper turns out to be the decisive factor that interferes with gold cyanidation by causing decrease in gold cyanidation recovery and increase in cyanide consumption. When cyaniding easily soluble copper content ( w E(Cu) ) lies in the range of 0 0.25%, it linearly affects gold cyanidation recovery ( R ) as well as cyanide consumption ( m c). The regression equations have been worked out to be R (%)=94.177 5-142.735 7 w E(Cu) with a correlation coefficient of -0.902 and m c=5.590 7+33.572 9 w E(Cu) with a correlation coefficient of 0.945, respectively.
文摘The regularities of anodic oxidation of thiosulfate ions on a gold electrode have been investigated using electrochemical methods in order to improve gold extraction. Effects of ammon, copper-ammon ions, pH and sulphite on anodic oxidation of thiosulfate ions have been examined in details. Results show that the anodic oxidation of thiosulfate ions is an inreversible reaction whose oxidizing peak potential is 620 mV/SCE in the absence of ammon. Oxidation rate increases with concentration of thiosulfate ions, but not in linear relation. It is also shown that ammon has significant effects on the oxidation of thiosulfate ions by causing great decrease in oxidation rate and negative shift of peak potential. The degrees of the rate decrease and negative shift increase with ammon concentration. When ammon concentration is increased to 1. 0 mol/L, the oxidation rate decreases to one fourth of that without ammon and the peak potential shifts from 620 mV/SCE to 350 mV/SCE.
文摘Heap leaching is a promising, less costly, alternative technology for processing low grade gold ores compared with traditional, energy intensive processes (e.g. autoclave/tank leaching). This research investigated the effectiveness of lime for enhancing gold leaching rates of gold ores from ajialongwa gold mine in china. Column and heaping experiments were performed using cyanide leaching solutions at pH=10, with and without lime (CaO). The presence of lime greatly increased gold leaching rates. Column leaching experiments showed without the addition of lime, there was 35.2% of gold leached. The addition of lime resulted in the release of 50.56% gold. Lime assisted cyanide of refractory gold was proved by heap leaching experiments.
文摘The ultra fine grinding and resin in pulp with pH value of 10 are used to extract gold from pyrite roster cinder. During leaching process, aluminium oxide ball is used as stirring medium, hydrogen peroxide as leaching agent and sodium hexametaphosphate as grinding agent. With AM 2б resin as absorber and sulfocarbamide as eluent, gold is recovered from cyanide pulp of pyrite roster cinder by resin in pulp. The effects of contact time, temperature and acidity etc. on the gold absorption are investigated by static methods and dynamic method respectively. The effects of flow rate of solution on dynamic adsorption and elution of gold are studied. The results show that AM 2б resin has good adsorbability in cyanide solution, and gold can be easily eluated from the loaded resin with 0.1mol/L hydrochloric acid and 1mol/L sulfocabamide. The adsorption rate and the elution of gold exceed 98%. When leaching time is 2 h, mass ratio of liquid to solid 4∶1, consumption of sodium cyanide 3 kg/t, concentration of hydrogen peroxide and sodium hexametaphosphate 0.05% respectively, adsorption time 30 min, temperature 10 30 ℃, volume of resin 3 mL, ratio of eluent to resin (10 20)∶1, velocity of eluent 1.5 mL/min, the leaching rate of gold reaches 85%. Compared with traditional leaching technology, it can reduce leaching time, avoid complex filter process, decrease sodium cyanide consumption and increase leaching rate of gold by 35%.
