1. Introduction

Gold metallurgical plants use the cyanide process for static leaching (heap leaching, for example) or dynamic leaching (stirred tank leaching). Some plants preconcentrate ore using conventional mineralurgical methods, with chemical attack on a gold-enriched concentrate.

The need to exploit more and more gold-bearing sulfide and arsenosulfide deposits, where gold is invisible (refractory ores), has led to the development of oxygen pressure leaching and bioleaching of ores or preconcentrates to make gold accessible to cyanide.

In general, for large, low-grade deposits, biohydrometallurgy on raw ore heaps becomes an ore preparation practice. For high-grade, rich deposits, cyanidation in stirred reactors, preceded or not by mineralurgical or oxygen pressure leaching operations, continues to be used.

Between 1990 and...