Case Study Analysis of Mineral Processing Operations at the Osun State Gold Mining Project: Efficiency and Recovery Assessment

This study presents a case study analysis of the mineral processing operations at the Osun State gold mining project in South West Nigeria, evaluating gold extraction efficiency, recovery rates, and operational performance relative to industry benchmarks. Artisanal and semi-industrial gold mining has expanded in Osun State following the discovery of significant alluvial and primary gold occurrences, and formal project-scale processing operations represent a more capital-intensive and regulated tier of this industry. Operational data covering a 12-month processing campaign are collected from the project operator, including head grade, milling circuit performance, gravity concentration efficiency, cyanide leaching recovery, carbon-in-pulp loading performance, and final product assay records. Metallurgical accounting and mass balance analysis are applied to identify efficiency losses across the circuit. Laboratory bottle roll leach tests are performed on representative ore samples to assess the potential for leach optimisation. Findings reveal an overall gold recovery of 84 percent against a benchmarked best-practice recovery of 91 percent for comparable ore types, with the primary recovery gap attributable to insufficient primary ore grind size and a suboptimal cyanide concentration regime. Economic modelling of the recovery shortfall indicates a potential revenue improvement of approximately USD 1.2 million per year at full production. Keywords: gold mining, mineral processing, recovery efficiency, cyanide leaching, Osun State.