The selective leaching and recovery of zinc in a zinciferous sediment from a synthetic wastewater treatment was investigated.The main composition of the sediment includes 6% zinc and other metal elements such as Ca,Fe...The selective leaching and recovery of zinc in a zinciferous sediment from a synthetic wastewater treatment was investigated.The main composition of the sediment includes 6% zinc and other metal elements such as Ca,Fe,Cu,Mg.The effects of sulfuric acid concentration,temperature,leaching time and the liquid-to-solid ratio on the leaching rate of zinc were studied by single factor and orthogonal experiments.The maximum difference of leaching rate between zinc and iron,89.85%,was obtained by leaching under 170 g/L H2SO4 in liquid-to-solid ratio 4.2 mL/g at 65 ℃ for 1 h,and the leaching rates of zinc and iron were 91.20% and 1.35%,respectively.展开更多
Citric acid was used to selectively extract cobalt from limonite-type laterite ores in the presence of ammonium bifluoride.The results show that ammonium bifluoride enhances the leaching of cobalt by citric acid,and 8...Citric acid was used to selectively extract cobalt from limonite-type laterite ores in the presence of ammonium bifluoride.The results show that ammonium bifluoride enhances the leaching of cobalt by citric acid,and 84.5% cobalt is extracted from a laterite ore containing 0.13% Co when leached at ambient temperature for 2 h with 30 g/L citric acid and 10 g/L ammonium bifluoride.Pyrolusite is reduced by citric acid during leaching,cobalt intergrown with which is liberated and subsequently chelated by the citric acid.The extraction of cobalt is enhanced in the presence of ammonium bifluoride because the matrix of silicate minerals is destroyed by ammonium bifluoride and the adsorbed cobalt is subsequently liberated.展开更多
In order to utilize low-grade manganese ore resources effectively, a hydrometallurgical process was developed for manganese extraction in dilute sulfuric acid medium, and the kinetics of leaching manga- nese was also ...In order to utilize low-grade manganese ore resources effectively, a hydrometallurgical process was developed for manganese extraction in dilute sulfuric acid medium, and the kinetics of leaching manga- nese was also investigated. At room temperature, manganese from low-grade manganese carbonate ores was extracted by sulfuric acid leaching without reductants. During the extracting process, single-factor analysis method was used to evaluate the effects of grinding fineness, sulfuric acid concentration, liquid-to-solid ratio, agitation rate and leaching time on the leaching efficiencies of Mn and Fe. The optimal leaching conditions are determined as coarse particles of below 2 mm size （without ball-milling）, sulfuric acid concentration of 0.86 mol/L, liquid-to-solid ratio of 5：1, agitation rate of 150 r/rain and leaching for 180 min at room temperature. Under the optimal conditions, the leaching efficiencies of Mn and Fe are 96.21g and 13.35%, respectively. In addition, through the experiments at different temper- atures, it is found that the leaching process follows the shrinking core model under the conditions of changing acid concentration and intermittent reaction device. Moreover, the apparent activations of effective diffusion and chemical reaction in the kinetic model are calculated to be 18.83 and 27.15 kJ/mol, respectively.展开更多
文摘The selective leaching and recovery of zinc in a zinciferous sediment from a synthetic wastewater treatment was investigated.The main composition of the sediment includes 6% zinc and other metal elements such as Ca,Fe,Cu,Mg.The effects of sulfuric acid concentration,temperature,leaching time and the liquid-to-solid ratio on the leaching rate of zinc were studied by single factor and orthogonal experiments.The maximum difference of leaching rate between zinc and iron,89.85%,was obtained by leaching under 170 g/L H2SO4 in liquid-to-solid ratio 4.2 mL/g at 65 ℃ for 1 h,and the leaching rates of zinc and iron were 91.20% and 1.35%,respectively.
基金Project(50725416) supported by the National Natural Science Foundation of China for Distinguished Young Scholars
文摘Citric acid was used to selectively extract cobalt from limonite-type laterite ores in the presence of ammonium bifluoride.The results show that ammonium bifluoride enhances the leaching of cobalt by citric acid,and 84.5% cobalt is extracted from a laterite ore containing 0.13% Co when leached at ambient temperature for 2 h with 30 g/L citric acid and 10 g/L ammonium bifluoride.Pyrolusite is reduced by citric acid during leaching,cobalt intergrown with which is liberated and subsequently chelated by the citric acid.The extraction of cobalt is enhanced in the presence of ammonium bifluoride because the matrix of silicate minerals is destroyed by ammonium bifluoride and the adsorbed cobalt is subsequently liberated.
基金the Key Laboratory of Resources of Nonferrous Metals Ministry of Education (Central South University) for the laboratories and financial support
文摘In order to utilize low-grade manganese ore resources effectively, a hydrometallurgical process was developed for manganese extraction in dilute sulfuric acid medium, and the kinetics of leaching manga- nese was also investigated. At room temperature, manganese from low-grade manganese carbonate ores was extracted by sulfuric acid leaching without reductants. During the extracting process, single-factor analysis method was used to evaluate the effects of grinding fineness, sulfuric acid concentration, liquid-to-solid ratio, agitation rate and leaching time on the leaching efficiencies of Mn and Fe. The optimal leaching conditions are determined as coarse particles of below 2 mm size （without ball-milling）, sulfuric acid concentration of 0.86 mol/L, liquid-to-solid ratio of 5：1, agitation rate of 150 r/rain and leaching for 180 min at room temperature. Under the optimal conditions, the leaching efficiencies of Mn and Fe are 96.21g and 13.35%, respectively. In addition, through the experiments at different temper- atures, it is found that the leaching process follows the shrinking core model under the conditions of changing acid concentration and intermittent reaction device. Moreover, the apparent activations of effective diffusion and chemical reaction in the kinetic model are calculated to be 18.83 and 27.15 kJ/mol, respectively.
