low molecular weight compolymers and terpolymers of the general structure : ## str1 ## wherein r 1 is hydrogen or a methyl radical , r 2 is hydrogen or coom and m is a hydrogen , alkali metal cation or ammonium ion , exhibit excellent depressive action in the flotation of non - sulfide mineral ores thereby resulting in improved selectivity and recovery . the low molecular weight copolymers and terpolymers , perform depressing action without resulting in any associated flocculation in the flotation system . these copolymers and terpolymers can be combined with other known depressing agents in nonsulfide ore flotation processes such as starch , dextrin , water soluble gum and the like , to obtain equivalent or improved selectivity and recovery than would be obtained using these depressants alone .