Mercury is removed from cyanide solutions, obtained by the cyanidation of gold ores, by mixing with a sulfide, preferably silver sulfide or zinc sulfide, to precipitate the mercury as insoluble HgS, which is filtered. Thus, 40 ml of a leach solution at ph 10 containing Au 20, Hg 10, Ag 10, and NaCn 500 mg/l is treated with 60 mg of Ag2S. Ninety-nine percent of the mercury from the leach solution was precipitated as HgS, which was separated by centrifugation.
U.S. Pat. 4,256,707, Mar. 17, 1981; Chem. Abstr. 93:135,825P