Utilization of fly ash to improve the quality of the acid mine drainage generated by oxidation of a sulphide-rich mining waste: column experiments.
The production of Acid Mine Drainage (AMD) as a result of the oxidative dissolution of sulphides is one of the main pollution problems affecting natural watercourses in mining environments with sulphide-rich residues. In this work, the generation of AMD was prevented by means of the addition of fly ash to sulphide-rich residues in non-saturated column experiments. A column experiment filled with a pyrite-rich sludge with artificial irrigation leached acid drainages (pH approx. 2) containing high concentrations of sulphate, iron and other metals. However, non-saturated column experiments filled with pyritic-rich sludge and fly ash drained leachates characterized by alkaline pH (pH up to 10), low sulphate concentration, and lack of iron and other metals in solution. The pyrite oxidative dissolution at high pH, as a consequence of the leaching of fly ash, favours the metal precipitation inside the column (mainly iron), the coating of pyrite grains, and the attenuation of the oxidation process, resulting in a great improvement in the quality of the leachates.
Pérez-López
Rafael
R
Department of Geology, University of Huelva, Campus El Carmen, E-21071 Huelva, Spain. rafael.perez@dgeo.uhu.es <rafael.perez@dgeo.uhu.es>
Nieto
José Miguel
JM
de Almodóvar
Gabriel Ruiz
GR
D001151:Arsenic / Q000032:analysis; D002118:Calcium / Q000032:analysis; D002244:Carbon / Q000737:chemistry*; D002845:Chromatography / Q000379:methods; D060729:Coal Ash; D003300:Copper / Q000032:analysis; D004339:Drug Compounding; D004553:Electric Conductivity; D006863:Hydrogen-Ion Concentration; D007220:Industrial Waste / Q000032:analysis*; D007854:Lead / Q000032:analysis; D008345:Manganese / Q000032:analysis; D008855:Microscopy, Electron, Scanning; D008906:Mining; D010084:Oxidation-Reduction; D052638:Particulate Matter / Q000737:chemistry*; D012722:Sewage / Q000737:chemistry*; D013431:Sulfates / Q000032:analysis; D013440:Sulfides / Q000737:chemistry*; D014877:Water Pollution, Chemical / Q000517:prevention & control*; D015032:Zinc / Q000032:analysis
D060729:Coal Ash; D007220:Industrial Waste; D052638:Particulate Matter; D012722:Sewage; D013431:Sulfates; D013440:Sulfides; D007854:Lead; D008345:Manganese; D002244:Carbon; D003300:Copper; D015032:Zinc; D001151:Arsenic; D002118:Calcium