ABSTRACT
Federal water quality standards in the United States require that mine-water discharges have a pH between 6 and 9, and total iron and manganese concentrations equal to or less than 3.0 mg L-1, and 2.0 mg L-1, respectively. At many active and inactive mine sites water quality standards are not met by the drainage and needs to be treated before is discharged. In the United States, the mining industry spends over $1 million per day to treat Acid Mine Drainage (AMD). Wildeman pointed out that handling the environmental aspects of a coal mining operation can be just as costly as the actual coal extraction, and abatement of present AMD is far more troublesome than planning to avoid the problem. When AMD comes in contact with limestone in an anoxic environment is assumed that limestone dissolution and subsequent production of alkalinity can proceed without inhibitory armoring.
