Experience of gold mining by heap leaching in Kazakhstan

About 70% of the proven reserves of indigenous gold in Kazakhstan are concentrated in five large deposits with a gold content in ores in the range of 5.5–8.0 g/t. It is possible to extract gold from the waste of primary ore processing, the amount of which exceeds 10 billion tons. There are 18 tailings dumps and 6 dumps containing gold and other metals in the Republic of Kazakhstan. The tailings dumps of the Aksu, Bestobe and Zholymbet mines are most suitable for gold extraction, the enrichment waste of which can be processed by direct cyanidation heap leaching or in the mode of pulp sorption concentration with cyanidation in counter-flow. The systematization and classification of types of dump products according to their suitability for heap leaching have been carried out, and potentially achievable technological efficiency has been shown in comparison with traditional primary processing of gold-bearing ores. A classification of methods for the intensification of heap leaching processes is proposed. The advantages of the option of sorption leaching of “resin in pulp” gold are indicated. An algorithm for gold extracting by heap leaching has been developed. For gold heap leaching, a technology option is recommended, which includes agglomeration of tailings, the use of sites with a stack height of 6 m and four stages of sorption of productive solutions, ensuring the gold extraction into commodity desorbate at the level of 65%.