Assessment of Environmental Impacts of Small-Scale Mineral Processing Operations in Kaduna State

This study assesses the environmental impacts of small-scale mineral processing operations, specifically ball milling and gravitational concentration of tantalite and columbite ores, in Kaduna State, North West Nigeria. Kaduna State hosts numerous artisanal and small-scale mining operations for tantalum and niobium minerals, and their associated processing activities generate fine mineral dust, process water discharges, and solid tailings with potential impacts on soil, surface water, and air quality. Environmental assessments were conducted at five active small-scale processing sites in Birnin Gwari Local Government Area using a combination of air quality monitoring, water sampling from site runoff, and soil sampling from tailings storage areas and adjacent agricultural land. Parameters assessed include airborne mineral dust and metals, process water pH and suspended solids, and soil concentrations of tantalum, niobium, manganese, and associated trace elements. Air monitoring reveals elevated mineral dust levels exceeding occupational exposure limits at grinding and concentration points due to absent or ineffective dust control. Process water discharged from gravity separation contains suspended solids exceeding 500 milligrams per litre, which affects downstream aquatic habitats. Tailings soils show high concentrations of manganese reaching 4,200 milligrams per kilogram, raising toxicity concerns for adjacent crops. The study documents a significant gap between the environmental impact of these operations and the oversight capacity of the Kaduna State Environmental Protection Agency. Keywords: small-scale mining, mineral processing, environmental impact, Kaduna State, tailings.