Selective precipitation/UV production of magnetite particles obtained from the iron recovered from acid mine drainage

Acid mine drainage (AMD) is recognized as one of the major sources of environmental damage in the coal mining industry. The active treatment of AMD involves the addition of alkaline neutralization reagents to raise the pH and precipitate dissolved metals as oxides/hydroxides. This treatment generates large volumes of sludge, which requires further treatment and final disposal. This study is aimed at analyzing the production of magnetite from the iron present in AMD using a selective precipitation/photoreduction combined process. The methods involved include the selective precipitation of iron as a ferric hydroxide, the dissolution of iron with sulfuric acid, the photoreduction of Fe3+ to Fe2+, and the conversion of ferric/ferrous hydroxides to magnetite. The magnetite particles were characterized and applied for paint production. The process can be adopted at AMD treatment plants, thereby reducing sludge waste issues and producing a valuable mineral.