Process Design for Igun Ore Deposit in Ilesha Goldfield


Occurrence of economic quantities of gold deposits over a large expanse of area and in finely disseminated form has been reported in Ilesha (Western Nigeria). The problem, however, has been unavailability of appropriate technology for efficient recovery of gold. This is the thrust of this work. This investigation, process design for Igun ore deposit in Ilesha goldfield, is aimed at proposing process flowchart for efficient recovery / extraction of gold from Ilesha gold ore accentuating on Igun deposit. The research essentially entails preliminary investigation, mineral processing and mineralogical characterization of the ore which involve sampling, concentration, particle size analysis, ore chemical analysis by fire-assay-gravimetric and atomic absorption spectrophotometric methods, petrography and x-ray diffractometry. In addition, amenability assessment of Igun gold deposit to amalgamation and percolation leaching was carried out. It has been established that free gold is scanty in the ore, rather the gold occurs as specks and inclusions finely disseminated in sulphide and quartz phases. It is postulated that Ilesha alluvial gold ore of which Igun gold deposit is a paradigm belongs to a non-refactory class. The experimental results confirm this as the gold ore is amenable to percolation cyanidation leaching but responded poorly to amalgamation. At the optimum leaching parameters of 6-hour retention time, sodium cyanide concentration of 0.3% and hydrogen ion concentration (pH) of 11.5, the highest recovery (63.60%) was obtained with the smallest size fraction of -75µm. These results form the basis for the evolution of a process flowchart for recovery of gold from Igun ore deposit which is aimed at sustainable gold production under safe environmental conditions.