Patent ID: 9545636
Date: 2017-01-17
CPC Classifications: B03B,B03D,C22B

Claim:
1. A method for processing mineral material containing precious metal with one or more sulfide minerals and containing non-sulfide gangue minerals comprising acid-consuming carbonate, the method comprising flotation processing, wherein the flotation processing comprises: flotation of the mineral material in aqueous liquid medium at a pH less than pH 7 with flotation gas to prepare a flotation concentrate enriched in sulfide minerals and associated precious metal relative to the mineral material as fed to the flotation and a flotation tail enriched in non-sulfide gangue minerals relative to the mineral material as fed to the flotation; and prior to the flotation, conditioning the mineral material, comprising treating a slurry including the mineral material with a conditioning gas comprising at least 5 volume percent carbon dioxide; and wherein: the mineral material comprises at least 1 weight percent acid-consuming carbonate before and after the conditioning; the conditioning comprises reducing the pH of the slurry from greater than pH 7 to a range of from pH 5 to pH 6.2 due mostly or entirely to carbon dioxide in the conditioning gas; during the conditioning and the flotation no more than 10 percent of acid-consuming carbonate in the mineral material as fed to the conditioning is decomposed; the flotation is conducted at a pH in a range of pH 5 to pH 6.2; and the mineral material comprises at least 1weight percent acid-consuming carbonate when the mineral material is fed to the flotation and the flotation tail and the flotation concentrate together comprise at least 1 weight percent acid-consuming carbonate relative to the combined weight of the flotation tail and the flotation concentrate.