Production of a Poly-ferric Sulphate Chemical Coagulant by Selective Precipitation of Iron from Acidic Coal Mine Drainage

The aim of this work was to produce a ferric sulphate rich solution from acidic coal mine drainage that could be used as coagulant. Precipitating the iron at pH 3.8, followed by dissolution in sulphuric acid, produced a coagulant consisting of 12.4% iron and 1.3% aluminium. Water treatment tests proved that this coagulant was as efficient as the coagulant chemicals conventionally used in water treatment plants. The process can be easily incorporated into conventional AMD treatment plants, thereby reducing sludge waste issues and producing a valuable chemical reagent.