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
Active carbon supported H 3PW 12 O 40 (PW 12 )solid acid catalysts are prepared and used in the etherification of light FCC gasoline with methanol.The effects of preparation conditions and the PW 12 loading on the act...Active carbon supported H 3PW 12 O 40 (PW 12 )solid acid catalysts are prepared and used in the etherification of light FCC gasoline with methanol.The effects of preparation conditions and the PW 12 loading on the activities of PW 12 (40)/C catalysts are studied.The results showed that the reflux time and the activating temperature influence the activity of the catalyst.As the loading of PW 12 on active carbon is lower, the reaction of PW 12 with the hydroxyl on the surface of active carbon makes the activity of the catalyst decrease.With the increase of loading of PW 12 on active carbon, the activities of the catalysts increase.Using PW 12 (40)/C as catalyst,under the conditions of reaction temperature 75?℃,pressure 0.8?MPa,molar ratio of methanol with tertiary carbonic olefins 1.0,and hourly space velocity 1.0 h -1 ,the ethers content in etherified light gasoline is up to 13.86%.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.
文摘Active carbon supported H 3PW 12 O 40 (PW 12 )solid acid catalysts are prepared and used in the etherification of light FCC gasoline with methanol.The effects of preparation conditions and the PW 12 loading on the activities of PW 12 (40)/C catalysts are studied.The results showed that the reflux time and the activating temperature influence the activity of the catalyst.As the loading of PW 12 on active carbon is lower, the reaction of PW 12 with the hydroxyl on the surface of active carbon makes the activity of the catalyst decrease.With the increase of loading of PW 12 on active carbon, the activities of the catalysts increase.Using PW 12 (40)/C as catalyst,under the conditions of reaction temperature 75?℃,pressure 0.8?MPa,molar ratio of methanol with tertiary carbonic olefins 1.0,and hourly space velocity 1.0 h -1 ,the ethers content in etherified light gasoline is up to 13.86%.
