Characteristics and environmental implications of coal fines at Hwange Colliery Company, Zimbabwe: A comprehensive analysis

Abstract

The study investigates the characteristics and environmental implications of coal fines at Hwange Colliery Company in Zimbabwe, aiming to address gaps in understanding and propose sustainable management strategies. The research encompasses a comprehensive analysis, including particle size distribution, proximate properties, elemental composition of coal fines, water and soil quality analysis. Sample collection and analysis were conducted following standardized procedures, revealing significant variations among sites in terms of particle size distribution and proximate properties. The sieve analysis revealed that around 80 % of the coal fines passed through the 2 mm sieve. Sites A and B exhibited lower moisture content and higher carbon content in contrast to site C, possibly due to variances in disposal duration. With an average gross calorific value of 17.43 MJ/kg, the coal fines showcase notable potential for energy extraction. Elemental analysis uncovered traces of heavy metals like Fe, Co, Cr, Ni, and Cu, posing an environmental risk if not managed appropriately. The water quality analysis revealed generally low turbidity levels in groundwater, with readings ranging from 0.34 to 0.55 NTU. However, elevated sulfate concentrations in some samples, averaging 113.67 mg/l, coupled with traces of nickel at levels up to 0.07 mg/l, warrant continuous monitoring to ensure compliance with safety standards. Soil analysis indicated the presence of heavy metals near coal fines dump sites, with lead levels reaching up to 52.32 mg/L, nickel at 36.17 mg/L, and copper at 53.70 mg/L, impacting soil enzyme activity and agricultural productivity. The study emphasizes the importance of improved waste management practices and sustainable utilization strategies to mitigate environmental risks and enhance resource efficiency in coal mining operations.