Iron Oxide Gold-bearing Ore Processing Based on Ore Characterization: Gravity Pre-concentration and Cyanide Dissolution

Abstract

Abstract The application of ore characterization and mineralogy holds a significant role in the development of a mineral processing route. The current investigation endeavors to evaluate the processing of iron oxide gold-bearing minerals exhibiting a gold grade of 1.07 g/ton. First, the mineralogical and microscopic characteristics of the ore sample were scrutinized. Subsequently, the recovery of gold from the ore was analyzed through gravity concentration and cyanidation techniques, following the characterization of minerals and ore using diverse methodologies. The outcomes revealed that the sample comprised free gold and oxidized structures, predominantly in the size fraction of -149 + 88 microns, and smaller within the range of 5–10 microns. Pre-concentration of gold-bearing minerals was performed via gravity separation techniques, including a shaking table and Knelson separator. The results indicated that the recovery of gold through these methods was limited, likely due to insufficient quantities of free gold present in the coarse-grained fractions. Subsequent cyanidation studies were conducted at pH 10.5, utilizing sodium cyanide concentrations of 3000 mg/l, and varying temperature, solid percentage, and size distribution parameters. The highest gold recovery rate of 95.03% was achieved in the size distribution of d80 = 53 microns, at a temperature of 80° C and a solid percentage of 25%. If a detailed technical and economic evaluation is conducted to optimize energy consumption and reduce grinding costs in the industry, it may be feasible to use the size distribution of d80 = 147 microns as the appropriate particle size for the cyanidation process, where a gold recovery rate of 90.51% was achieved at ambient temperature with a solid percentage of 30%.