Selective flotation of bastnaesite from monazite in rare earth concentrates using potassium alum as depressant

Electrokinetic and flotation studies were carried out on single particles o f bastnaesite and monazite to develop a flotation scheme for selectively re moving monazite in the rare earth bulk concentrate from the Baiyunebo mine, in China (60.7% rare earth oxides or REO, 75% as bastnaesite and 25% as mo nazite). Low additions of potassium alum were found to efficiently depress monazite at pH 5 without affecting the flotability of bastnaesite with the collector benzoic acid. The bulk concentrate was treated through this schem e, and 85% of the bastnaesite was recovered in a concentrate that assayed 6 9.5% REO and contained 97% bastnaesite. The depressing effect of potassium alum appeared to be due to the preferential adsorption of hydrolyzed alumin um species on monazite in comparison to bastnaesite. (C) 2000 Elsevier Scie nce B.V. All rights reserved.