Development of resource saving technology for gold recovery with intensifying additives

Abstract

Study of biochemical leaching performances in gold-bearing sulfide minerals processing enabled to develop environmentally sound technology of enhanced gold recovery from rebellious gold-containing raw materials. It was found that the Т-10 IMO bacteria activity contributes to increasing system oxygen concentrations and incrementing in rates of oxygen delivery onto surface of gold-bearing minerals. Bacteria activity products, i.e., amino-acids (А), support the formation of such heterocomplexes as [A-Au-CN]– , providing additional gold recovery into solutions. Technological properties of proposed bacteria solutions were studied. It was found that the proposed bacteria inoculants are capable to growing directly in process of raw materials leaching within a large pH range of media containing cyanides and thiosulfates. They oxidize the sulfur to the sulfate, as well as the antimony (III) and arsenic (III) sulfides to the pentads. For the first time, the hydrophobic cells properties, metabolites emulsifying efficiency, adsorption properties, wetting ability, surface tension and electro-kinetic potential of new bacteria strain solutions were studied as compared with chemical solutions. It was found that the proposed bacteria inoculants reduce surface tension at the solvent-mineral and solvent-concentrate phase boundaries. All above-mentioned effects enhance mass-transfer processes efficiency. IR-spectroscopy of new bacteria strain culture liquid allowed identifying available amino acids which substantially contribute to heterocomplex anion [A-Au-CN]– formation. Active involvement of heterotrophic bacteria in gold dissolving processes was identified. It was shown that the structure of metals complexes is substantially modified at intensive pulp agitation and during long-term storage. Fractional-order reaction in biochemical and chemical gold leaching was identified. It evidences that the gold and impurity metals dissolving processes advance in synchronism. The both processes are running in diffusion zone. Biochemical leaching has advantages over chemical leaching, i.e., it provides enhanced rates of precious metals dissolving, improved gold recovery by 20–30%, decreased cyanide consumption by 50%. At the same time it allows to decontaminate dangerous substances contained in productive solutions produced in rebellious gold-containing raw materials processing.