Process of extracting gold and silver from ores and mining by-products

Abstract

The invention relates to a process for the extraction of gold and silver from ores and mining by-products. The process according to invention consists in treating ores and mining residues having a content of 0.5 . . . 12 ppm Au with a solution of ammonium thiosulphate, recycled at a temperature of 15-25° C.; the filtrate resulting after solubilization is subjected to an electrolytic extraction with high-alloy electrodes with a current density of 200 . . . 250 A/m 2 , until the electrolyte reach a concentration of 5-15 ppm Au, 1-100 ppm Ag and 0.1-1.0 g/1 Cu; afterwards, the separated cement is filtered off and dissolved in aqueous ammonia, dried at a temperature of 105° C. and melted at a temperature of 1200° C., resulting a Au-Ag alloy, which is processed by electrochemical and thermal refining operations, from which there are obtained Au and Ag of high purity.

1 . Process of extracting gold and silver from gold ores and mining by-products, which comprises treating gold ores, pyrite concentrates or mining by-products consisting of mining and metallurgical residues, characterized in that:
 solubilizing the raw material in a solution of ammonium thiosulphate, recycled from the process, with a content of 10 to 25 g/l (NH 4 ) 2 S 2 O 3 ; 0.1 to 1.0 g/l Cu; 0.3 to 0.4 g/l NH 4 OH at a solid:liquid ratio of 1:1 . . . 1:1.5, at a temperature of 15-25° C. for 2-4 hours;   the filtrate obtained after dissolution, with a content of 10 to 25 g/l (NH 4 ) 2 S 2 O 3 , 6-20 ppm Au, 2-150 ppm Ag, 0.12-1,2 g/l Cu, 0.3-0.4 g/l NH 4 OH, is subjected to an electrolysis with high-alloy steel electrodes with a current density of 200-250 A/m 2 , until the electrolyte has a concentration of 5-15 ppm Au, 1-100 ppm Ag and 0.1-1.0 g/l Cu;   the cementum separated in electrolysis cells, after a total of 20 cycles, is filtered off and dissolved in aqueous ammonia having a concentration of 20% NH 3 at a solid:liquid ratio of 1:5   1:10 for 3-5 hours; after which it is filtered, washed with water, dried at a temperature of 105° C. and melted in a alkaline-reducing medium at a temperature of 1,200° C., resulting a Au—Ag alloy, from which, by electrochemical and thermal refining, there are obtained gold and silver 99.9%, and the filtered solution copper ammine—is recycled to process, in order to correct the copper content of the electrolyte used in the leaching of raw materials.