Archippe Manzila Archippe Manzila

Project Title: A study of alternative techniques for gold extraction from alluvial deposits in artisanal gold mining (AGM).

Research Theme: Artisanal and Small-scale Mining

Supervisor(s): Thandazile Moyo, Jochen Petersen

Abstract

Artisanal gold mining (AGM) refers to operations that make use of low-tech or rudimentary techniques to mine and process gold. The AGM sector provides a source of livelihood for millions of people worldwide and continues to expand as a result of the ever-rising price and demand for gold on the market. Artisanal miners mostly extract their gold by amalgamation with mercury (Hg) to form an alloy with gold, called amalgam. Despite its simplicity of application and quick return, mercury amalgamation presents serious health and environmental risks. These arise primarily from the vaporisation of Hg during amalgam burning and the dumping of Hg rich tailings into local water streams. This anthropogenic Hg produced can cause serious neurological disorders and even death if inhaled or ingested. Due to these risks, new technologies such as borax smelting, cyanide, thiourea, thiosulphate and chlorine leaching have been developed to substitute the use of Hg. Most of these methods have, however, not been successful due to their complexity making them unattractive to artisanal miners.

My research aims to investigate the application of borax smelting, cyanide and thiosulphate leaching as efficient alternatives to mercury amalgamation for the recovery of gold from alluvial deposits. The investigation will particularly look at the extractions and recoveries that can be achieved with the three technologies and compare their performance to mercury amalgamation from an economic, safety and environmental standpoint.