Abstract:
The recovery of gold concentrates has mainly been carried out by processes such as gravity concentration, amalgamation, and cyanidation. The latter processes use chemical reagents which pose extensive detrimental effects on the ecosystem; hence, the need to explore alternative methods of gold recovery while enhancing environmental sustainability. One such method is coal gold agglomeration (CGA) assisted flotation. This research employed the CGA assisted flotation method to recover gold concentrates from the Iperindo-Ilesha lode gold deposit, Osun State, Nigeria. Five (5) kg crude gold ore was sourced, comminuted and characterized. 3.2 kg of coal sourced from Onyeama-Enugu was subjected to proximate analysis. Coal-gold agglomeration (CGA) assisted flotation process was carried out using conventional reagents while varying oil-coal ratio and collector (potassium amyl xanthate – PAX) dosage at constant stirring speed and coal particle size of 1600 rpm and 500 μm respectively. Chemical analysis results revealed that the run-of-mine assayed 4.10 ppm. The scanning electron microscopy coupled with energy dispersive spectroscopy (SEM/EDX) analysis revealed that the surface of the bulk ore has a rough topography of mineral particles sparsely distributed abroad the ore matrix. The presence of gold within the ore matrix and high concentration of silica was confirmed. The X-ray diffractometry result also revealed that quartz was predominant in the ore matrix alongside trace associated minerals such as dolomite (CaMg(CO3)2), sylvanite ((Au,Ag)Te4), and annite (KFe32+AlSi3O10(OH)2). The estimated work index of the ore was 10.78 kWh/ton. The proximate analysis of coal samples showed a volatile matter content of 27.34 wt. %, 1.95% moisture content, 14.50% ash content and 56.20 % fixed carbon. An optimal gold grade of 150 ppm and % gold recovery of 76.46% was obtained at an oil-coal ratio of 0.1 by weight, PAX dosage of 0.3 g, stirring speed of 1600 rpm, and 500 μm coal particle size. At this optimal value, the enrichment and concentration ratios were 1.45 and 1.90 respectively which also attest to the optimal efficiency of the CGA process. Conclusively, the applicability of CGA to the processing of Iperindo-Ilesha gold deposit was viable.
