Coal mining and acidic-mine drainage :causes and abatement techniques

Abstract

The term acidic-mine drainage is applied to acidic water draining from mining areas. The chemical controls of acidic-mine drainage include the amount of mineral sulfides present in the mined rock, the crystallinity of the sulfides, and the presence of carbonate minerals. Physical controls are based on the presence of air and water. The ability of certain bacteria to catalyze the acid-producing reactions is a biological control. Acid/base accounting is an abatement technique in which the acid potential of a rock is weighed against its base potential. Various alkaline agents, primarily limestone, can be used to neutralize acidic-mine drainage. Neutralization results in an adjustment of pH and chemical precipitation. It will not decrease the iron and sulfate contents of the water. The use of phosphate rock has been proposed as an abatement alternative. It contains the mineral apatite, which has the ability to prevent the acid-producing reactions from taking place.