Empirical Analysis of Particle Size Distribution and Mineral Liberation in Coltan Processing at Small-Scale Plants in Plateau State

Efficient recovery of columbite-tantalite (coltan) in small-scale processing plants is critically dependent on achieving adequate mineral liberation through grinding, yet liberation analysis has not been applied systematically to Nigerian coltan processing operations. This study empirically analyses particle size distribution, mineral liberation, and processing efficiency relationships at three small-scale coltan processing plants in Plateau State, North Central Nigeria. Automated mineralogy using a TESCAN Integrated Mineral Analyser was applied to polished sections of feed, gravity concentrate, and tailings samples collected at each plant. Liberation spectra were generated for coltan, ilmenite, and quartz at each measured size fraction. Comparison of liberation profiles against plant recovery data identified optimal and sub-optimal size classes for processing. Results demonstrate that coltan liberation above 90 percent is achieved at 80 percent passing 500 micrometres for the Plateau coltan ore types studied, while current grinding practice achieves 80 percent passing only 1,200 micrometres at two of the three plants, resulting in substantial composite particle losses to tailings. Tailings assays indicate coltan losses equivalent to 18 to 27 percent of contained metal value per tonne of feed processed. Grinding circuit upgrades estimated to cost below 8 million Naira per plant are projected to recover 15 to 22 percent additional coltan. The study provides liberation data applicable to plant optimisation decisions for Plateau State coltan operators. Keywords: mineral liberation, coltan processing, Plateau State, particle size, small-scale mining.