ABSTRACT
Polymeric depressants have been shown to be particularly advantageous in depressing gangue minerals. In some cases, such as the flotation of sylvinite potash ore, the use of a polymeric depressant is almost indispensible. This chapter discusses the important factors governing the effectiveness of polymeric depressants from a chemical viewpoint. The most commonly encountered functional groups on polymeric depressants are hydroxyl, carboxylate, sulfonate, and amine. Polymeric depressants usually bear a large number of functional groups. The authors have found that their steric arrangements may have a significant influence on the effectiveness of the depressant. Polymeric depressants based on ionic functional groups such as carboxylates, sulfonates, and amines have to be designed with a proper level of charge density. The term selective flocculation has been popularized by many well-known investigators in mineral flotation as the mechanism for separating the gangue and the valuables. In most cases, polymeric depressants do function with selective flocculation as the modus operandi.
