Pretreatment Using Alkaline Sulfide Leaching and Nitrogen Species Catalyzed Pressure Oxidation on a Refractory Gold Concentrate

Hydrometallurgical technology for the pretreatment of refractory gold concentrates has been developed at Sunshine Mining and Refining Company. It employs a patented nitrous-sulfuric acid pressure leaching process which' was proven industrially at the Sunshine refinery. Additionally, pretreatment for removal of antimony and some other impurities is done with alkaline sulfide leaching. This paper will discuss the successful application of these two technologies for pretreatment of a refractory gold concentrate prior to CIL gold recovery. A complex gold concentrate composed of pyrite, arsenopyrite and stibnite was tested. Results of antimony leaching in alkaline sulfide media will be discussed including some details of a novel and selective recovery method for gold leached by polysulfide or thiosulfate" Also, the factors important in and the results of the application of nitrogen species catalyzed pressure leaching to refractory gold concentrates will be detailed.