Extraction of Rare Earth from Rare Earth Mine Using Ammonium Sulfate Roasting

The technology of (NH4 )2SO4 roasting water bath leaching was used for extracting rare earth from rare earth concentrate and rare earth tailings, respectively. Bastnaesite was transformed into soluble sulfate by roasting with (NH4) 2 SO4. Preroasting bastnaesite played a positive role in turning bastnaesite into sulfate rare earth, then increasing the leaching rate. The highest leaching rate of Ce reaches 90%. High – grade magnetite concentrate and rare earth slag were obtained by coal – based reduction roasting and magnetic separation. Roasting process also benefited phase transition of rare earth. The main influence factors on the leaching rates of rare elements in roasted products were investigated including amount of ammonium sulfate, roasting temperature and roasting time. The optimized experimental conditions were obtained as follow- ing: 4:1 of (NH4 )2SO4 to slag mass ratio, 350 ℃ of roasting temperature for 45 min, 80 ℃ of water bath leaching tempera- ture for 2 h and 10 mL ·g-1 of leaching liquid – solid ratio, the highest leaching rates of rare earth( La, Ce, Nd) reach 82. 83% ,76. 53% ,77. 14%, respectively.