Effect of Particle Size on Leachate Formation Characteristics from Gold Mine Waste Rocks: At Source Acid Mine Drainage Management in Tanzania

Abstract

Waste rocks from gold mining operations represents a significant environmental burden and impairs sustainable environmental management in developing countries. This study focused on understanding the leachate properties of different particle sizes (>10mm, 20mm, 30mm and 50mm) from the waste rock dump (WRD) - GPAF in the 30 liters containers to represent waste rocks by using quick static testing to determine a more rational design basis for material storage and management. This study found that small particle sizes of waste rocks with <10 mm showed a strong leaching with a low pH of 3.5, while large particle sizes of 50 mm showed a high pH of 6.5. Metal leaching of small particle sizes had a higher concentration of Manganese, Zinc and Iron than large particle size. Similarly, sulphate concentration from leachate of small particle size of waste rocks had higher levels than large particle size. In addition, this study also demonstrated that the majority of dissolved metals (Mn, Zn and Fe) leached higher in the low pH (3.5) leachate. This study recommended that great emphasis be taken on the separation of small particles from large particle sizes of mine waste rocks during and after mining operations to reduce the risk of metal leaching and the possibility of acid mine drainage (AMD) formation and pollute surface and groundwater.