GB859269A - Copolymers of acrylamide and vinyl aromatic sulfonates - Google Patents

Abstract

Copolymers of 99 to 90 mole per cent of acrylamide and 1 to 10 mole per cent of at least one compound selected from vinyl benzene sulphonic acid, vinyl benzyl sulphonic acid, water-soluble alkali and alkaline earth metal salts of said acids, and alkyl substitution products of said acids and salts having 1 or 2 alkyl radicals, each containing 1 to 3 carbon atoms, attached to the benzene nucleus, may be prepared by copolymerizing acrylamide with the acid or salt in aqueous solution at a pH of 3 to 9. The aqueous media may contain alcohols such as methyl alcohol, ethyl alcohol and isopropyl alcohol. The polymerization may be catalysed by soluble free-radical polymerization catalysts, e.g. sodium persulphate, potassium persulphate, ammonium persulphate, hydrogen peroxide and tertiary butyl hydroperoxide, or by ultraviolet light, X-rays, g -rays and high energy electrons. Traces of acrylamide peroxide normally present in the acrylamide may be sufficient to initiate polymerization in the presence of sodium sulphite. Examples describe the copolymerization of acrylamide with sodium vinyl benzyl sulphonate and sodium vinyl benzene sulphonate. The products may be used for flocculating suspensions of mineral solids, e.g. uranium ores.ALSO:Sodium vinyl benzylsulphonate may be prepared by adding vinylbenzyl chloride portionwise with agitation to an aqueous solution of sodium sulphite at room temperature. Unreacted vinylbenzyl chloride may be extracted with benzene and the sodium vinylbenzyl-sulphonate crystallised by chilling the aqueous solution.ALSO:A method of flocculating aqueous suspensions of finely divided mineral solids comprises admixing with the suspensions aqueous solutions of water-soluble high molecular weight copolymers of 99 to 90 mole per cent acrylamide and 1 to 10 mole per cent acrylamide and 1 to 10 mole per cent of at least one sulphonated vinyl aromatic compound selected from vinylbenzene sulphonic acid, vinylbenzyl sulphonic acid, water-soluble alkali and alkaline earth metal salts of said acids, and alkyl substitution products of said acids and salts having 1 or 2 alkyl radicals, each containing 1 to 3 carbon atoms, attached to the benzene nucleus. The flocculated material may be separated by decantation, filtration or centrifugation Examples describe the flocculation of aqueous slurries of acid-leached South African uranium ore using (6 and 8) acrylamide-sodium vinylbenzene sulphonate copolymers, (7) acrylamide-sodium vinylbenzyl sulphonate copolymers and, for comparison, polyacrylamide.