Introduction

A heap consisting of an oxide gold-bearing ore containing 3.5 g/t of gold and 14.0 g/t of silver was leached by solutions containing amino acids of microbial origin and thiosulphate as goldcomplexing agents. 68.4% of the gold and 53.6% of the silver were leached within 20 days in this way. The pregnant solutions after leaching were treated by cementation with metallic zinc. Mixed gold-bearing concentrates containing also zinc and copper as valuable components were the products from the cementation