In recent years,a new process for leaching scheelite concentrates with sulfur-phosphorus mixed acid has been successfully industrialized.This process suffers from the elimination of the retarding effect of calcium sul...In recent years,a new process for leaching scheelite concentrates with sulfur-phosphorus mixed acid has been successfully industrialized.This process suffers from the elimination of the retarding effect of calcium sulfate,the selective extraction of tungsten from the H_(3)PW_(12)O_(40)-H_(2)SO_(4)-H_(3)PO_(4)mixture solution,and the removal of introduced phosphorus.Therefore,in this paper,we investigated the inhibition measures of a calcium sulfate-blocking membrane,the selective extraction of tungsten by ion exchange,and the removal of phosphorus by the magnesium ammonium salt method.The results showed that the addition of calcium sulfate whisker seeds and a higher H_(3)PO_(4)concentration inhibited spontaneous diffuse nucleation,promoted crystal growth,and avoided the formation of a dense blocking film.About 98 wt.%of the scheelite concentrate was digested by H_(2)SO_(4)-H_(3)PO_(4).The selective adsorption of PW_(12)O_(40)^(3-)was realized using D301 resin,and the extraction efficiency of tungsten exceeded 99.9%.After desorption with ammonia water,PW_(12)O_(40)^(3-)was depolymerized into WO_(4)^(2-)and PO_(4)^(3-).99.9 wt.%of phosphorus was removed in the form of MgNH_(4)PO_(4)by the magnesium ammonium salt method,and the residual phosphorus concentration in the solution was lower than 10 mg·L^(-1).After purification,the highest-grade ammonium paratungstate product was prepared by evaporative crystallization.展开更多
基金jointly supported by the National Natural Science Foundation of China(No.51334008)the Basic Science Center of the National Natural Science Foundation of China(72088101)the National Key Research and Development Program of China(No.2022YFC2904505)。
文摘In recent years,a new process for leaching scheelite concentrates with sulfur-phosphorus mixed acid has been successfully industrialized.This process suffers from the elimination of the retarding effect of calcium sulfate,the selective extraction of tungsten from the H_(3)PW_(12)O_(40)-H_(2)SO_(4)-H_(3)PO_(4)mixture solution,and the removal of introduced phosphorus.Therefore,in this paper,we investigated the inhibition measures of a calcium sulfate-blocking membrane,the selective extraction of tungsten by ion exchange,and the removal of phosphorus by the magnesium ammonium salt method.The results showed that the addition of calcium sulfate whisker seeds and a higher H_(3)PO_(4)concentration inhibited spontaneous diffuse nucleation,promoted crystal growth,and avoided the formation of a dense blocking film.About 98 wt.%of the scheelite concentrate was digested by H_(2)SO_(4)-H_(3)PO_(4).The selective adsorption of PW_(12)O_(40)^(3-)was realized using D301 resin,and the extraction efficiency of tungsten exceeded 99.9%.After desorption with ammonia water,PW_(12)O_(40)^(3-)was depolymerized into WO_(4)^(2-)and PO_(4)^(3-).99.9 wt.%of phosphorus was removed in the form of MgNH_(4)PO_(4)by the magnesium ammonium salt method,and the residual phosphorus concentration in the solution was lower than 10 mg·L^(-1).After purification,the highest-grade ammonium paratungstate product was prepared by evaporative crystallization.
