Non-cyanide reagents for gold extraction from the products of pressure oxidation of sulphide concentrates

Abstract

The standard pressure oxidation (POX) technology for sulfide gold-bearing concentrates processing has many problems associated with the use of cyanide as a gold lixiviant. Therefore, works to find of alternative gold recovery methods are currently now. This paper describes some technological solutions, which can become a real alternative to cyanide technology in the future. Five different refractory gold-bearing concentrates from Russian gold deposits were investigated. Concentrate 1 was gold-copper concentrate. Concentrate 2 was gold-pyrite concentrate. Concentrates 3–5 were pyrite-arsenopyrite double refractory concentrates. The POX tests at the temperature of 110, 200 and 220 oC and the oxygen pressure of 1.5, 2.4 and 3.0 MPa were carried out. Chloride, thiosulfate, sulfite and thiocyanate were tested as gold lixiviants. The gold recovery by non-cyanide methods was 97–99%, and from double refractory concentrates was 86–92%. The tested reagents are less toxic than cyanide and makes possible to recover gold in acidic POX slurry. As well, “POX-pyrometallurgical” technology for precious metals recovery from POX cakes to lead collector was tested in pilot scale. It was shown that “POX-pyrometallurgical” technology for preg-robbing concentrates could be used. The recoveries of gold and silver are 97 and 96%, respec tively.