There is disclosed a multivalent cation containing copolymer derived from one or more ethylenically unsaturated acids. The copolymer has the following characteristics: (a) an intrinsic viscosity of at least about 3 dl/g when measured in 1 M Na Cl solution at 25° C.; (b) the copolymer is derived from a monomer mixture comprising an ethylenically unsaturated acid and at least one comonomer, the ethylenically unsaturated acid present in an amount in the range of from about % to about 65% by weight; and (c) a residual comonomer content is less than 1000 ppm when the comonomer is an acrylamide. The copolymer, inter alia, is useful as a flocculant for treating an aqueous slurry comprising particulate material, preferably tailings from a mining operation.