A hydrometallurgical process for tungsten extraction and recovery from scheelite is reported.The technology includes leaching scheelite using phosphoric acid as chelating agent in nitric acid solutions,extracting tung...A hydrometallurgical process for tungsten extraction and recovery from scheelite is reported.The technology includes leaching scheelite using phosphoric acid as chelating agent in nitric acid solutions,extracting tungsten by solvent extraction and reusing leaching agent.In the leaching process,affecting factors,such as temperature,leaching time,nitric acid and dosage of phosphoric acid,were examined on recovery of tungsten.Results show that more than 97%of tungsten could be extracted under conditions of leaching temperature of 80-90°C,HNO3 concentration of 3.0-4.0 mol/L,liquild-to-soild ratio of 10:1,H3PO4 dosage of 3 stoichiometric ratio and leaching time of 3 h.Solvent extraction was then employed for the W recovery from the leachate with a organic system of 40%(v/v)N235,30%(v/v)TBP,and 30%sulfonated kerosene.Approximately 99.93%of W was extracted and ammonium tungstate solution containing 193 g/L W was obtained with a stripping rate of 98.10%under the optimized conditions.展开更多
The recovery of nickel from molybdenum leach residue by the process of segregation roasting-sulfuric acid leaching-solvent extraction was investigated. The residue was characterized by microscopic investigations, usin...The recovery of nickel from molybdenum leach residue by the process of segregation roasting-sulfuric acid leaching-solvent extraction was investigated. The residue was characterized by microscopic investigations, using X-ray fluorescence spectrometry （XRF） and X-ray diffractometry （XRD） techniques and the residue after segregation roasting was characterized by chemical phase analysis method. A series of experiments were conducted to examine the mass ratio of activated carbon （AC） to the residue, segregation roasting time and temperature, sulfuric acid concentration, liquid-to-solid ratio, leaching time, leaching temperature, addition amount of 30% H2O2, stirring speed （a constant） on the leaching efficiency of nickel. A maximum nickel leaching efficiency of 90.5% is achieved with the mass ratio of AC to the residue of 1：2.5, segregation roasting time of 2 h, segregation roasting temperature of 850 ℃, sulfuric acid concentration of 4.5 mol/L, liquid-to-solid ratio of 6：1, leaching time of 5 h, leaching temperature of 80 ℃, addition of 30% H202 of 0.6 mL for 1 g dry residue. Under these optimized conditions, the average leaching efficiency of nickel is 89.3%. The nickel extraction efficiency in the examined conditions is about 99.6%, and the nickel stripping efficiency in the examined conditions is about 99.2%.展开更多
基金Project(51334008) supported by the National Natural Science Foundation of China
文摘A hydrometallurgical process for tungsten extraction and recovery from scheelite is reported.The technology includes leaching scheelite using phosphoric acid as chelating agent in nitric acid solutions,extracting tungsten by solvent extraction and reusing leaching agent.In the leaching process,affecting factors,such as temperature,leaching time,nitric acid and dosage of phosphoric acid,were examined on recovery of tungsten.Results show that more than 97%of tungsten could be extracted under conditions of leaching temperature of 80-90°C,HNO3 concentration of 3.0-4.0 mol/L,liquild-to-soild ratio of 10:1,H3PO4 dosage of 3 stoichiometric ratio and leaching time of 3 h.Solvent extraction was then employed for the W recovery from the leachate with a organic system of 40%(v/v)N235,30%(v/v)TBP,and 30%sulfonated kerosene.Approximately 99.93%of W was extracted and ammonium tungstate solution containing 193 g/L W was obtained with a stripping rate of 98.10%under the optimized conditions.
基金Project(2007CB613604)supported by the National Basic Research Program of China
文摘The recovery of nickel from molybdenum leach residue by the process of segregation roasting-sulfuric acid leaching-solvent extraction was investigated. The residue was characterized by microscopic investigations, using X-ray fluorescence spectrometry （XRF） and X-ray diffractometry （XRD） techniques and the residue after segregation roasting was characterized by chemical phase analysis method. A series of experiments were conducted to examine the mass ratio of activated carbon （AC） to the residue, segregation roasting time and temperature, sulfuric acid concentration, liquid-to-solid ratio, leaching time, leaching temperature, addition amount of 30% H2O2, stirring speed （a constant） on the leaching efficiency of nickel. A maximum nickel leaching efficiency of 90.5% is achieved with the mass ratio of AC to the residue of 1：2.5, segregation roasting time of 2 h, segregation roasting temperature of 850 ℃, sulfuric acid concentration of 4.5 mol/L, liquid-to-solid ratio of 6：1, leaching time of 5 h, leaching temperature of 80 ℃, addition of 30% H202 of 0.6 mL for 1 g dry residue. Under these optimized conditions, the average leaching efficiency of nickel is 89.3%. The nickel extraction efficiency in the examined conditions is about 99.6%, and the nickel stripping efficiency in the examined conditions is about 99.2%.
