METHOD OF EXTRACTION OF NOBLE METALS FROM GRAVITATIONAL SILICATE CONCENTRATES CONTAINING GOLD AND SILVER Russian patent published in 2004 - IPC

FIELD: non-ferrous metallurgy; methods of extraction of noble metals from silicate concentrates obtained in processing auriferous ores containing gold in form of sulfide solutions and native gold. SUBSTANCE: proposed method includes introduction of one of compounds, such as calcium oxide, ferric oxide and materials containing these oxides into starting concentrate as flux for forming slag of preset basicity at simultaneous addition of copper-containing material followed by melting and forming of matte and silicate slag and separation of slag and matte. Used as copper-containing additive is floatation concentrate containing copper, gold and silver dissolved in sulfides; sulfidizing agent is additionally introduced in form of material containing calcium sulfate or in form of calcium sulfate formed in the course of mixing components of calcium oxide and/or calcium hydroxide and sulfuric acid and carbonic reductant. Addition of floatation concentrate is carried out by mixing pulps of gravitational and floatation concentrates followed by thickening, settling and filtration, drying thickened mixture of concentrates, mixing with other additives and palletizing accompanied by hardening and final drying; then mixture is molten for matte and slag. Drying is performed at residual humidity of 25-30% and palletizing is performed by modulating or briquetting. Drying concentrate mixture and palletizing are combined in one unit. After holding at heat, palletized material is subjected to heat treatment in counter flow of hot gases supplied from melting unit followed by charging hot cinder into melting unit. EFFECT: high degree of extraction of copper, gold and silver; enhanced efficiency; reduced power requirements. 8 cl, 1 tbl, 3 ex