Selective Flotation of Scheelite and Calcite

Abstract

The gold tailings from Gold Fields containing low scheelite values has a compled mineralogy with hornblende, quartz, arsenopyrite and calcite as major gangue minerals. The most difficult problem in scheelite flotation is not the removal of the siliceous or sulphide gangue, but the separation of Scheelite and calcite minerals which have similar surface properties. This is greatly influenced by many factors(1)such as (1) the extent of adsorption of the collectors (2) the dissolution of the minerals and the interference by the released species and (3) the intera-ction of adsorbed ions with the mineral surface. Direct flotation tests to recover scheelite from tailings failed due to the dilution of the concentrate by calcite. Hence to adopt the flotation process successfully, it is nece-ssary to depress the calcite selectively which is not achi-eved easily(2) due to the presence of small amounts of Ca, Mg and Fe salts and the lean grade of the ores to be treated. Slime coating(3) is also another factor adver-sely affecting the flotation of scheelite. The present study is an attempt to improve the selectivity of separ-ation of scheelite, based on the flotation of pure clacite-scheelite system using sodium oleate as collector.