Investigating the effectiveness of ammonium thiosulfate in gold recovery.

Abstract

With the increasing environmental pollution and health risks in communities within and around gold mining areas in Tiira, Uganda, there is a growing need to find safer gold extraction methods. The government of Uganda, along with NGOs like the National Environmental Management Authority (NEMA) and the World Health Organization (WHO), has identified cyanide and mercury as major pollutants in artisanal and small-scale gold mining (ASGM). In Tiira, most small-scale miners rely on mercury amalgamation, which releases toxic mercury into the air, water, and soil. This exposure has severe health effects, including damage to the nervous system, kidneys, liver, and immune system. Additionally, mercury use in gold recovery results in impurities in the final gold product. This project investigates the effectiveness of ammonium thiosulfate (ATS) in gold recovery as a safer alternative to traditional methods. The study objectives are: to characterize the gold sample; to determine gold leaching efficiency of ammonium thiosulfate under varying conditions; and to optimize the operational parameters for maximum recovery. Chapter One introduces the study, presenting the background of the problem, clear research objectives, the scope of the study, and the justification for exploring ATS as an alternative gold recovery method. Chapter Two consists of the literature review, which examines previous research on gold extraction methods, comparing the efficiency, environmental impact, and feasibility of ATS leaching versus mercury amalgamation and cyanide leaching in small-scale mining. The chapter also highlights case studies where thiosulfate leaching has been successfully applied. Chapter Three covers the methodology used in the research. This involved collecting and characterizing a gold ore sample from Tiira, conducting laboratory tests under varying pH, temperature, and ATS concentrations, and analyzing the effectiveness of ATS using both qualitative and quantitative techniques. Chapter Four presents the results and discussions of all tests and experiments carried out. It includes a detailed analysis of the gold content in the sample, recovery efficiency under different conditions, and the optimization of parameters for improved leaching performance. The conclusion section summarizes the key findings, highlights the limitations and challenges encountered during the research, and provides recommendations for improving the use of ATS in small-scale mining. The references section cites various articles, journals, and reports that contributed to this study.