Patent ID: 6932909

Claim:
A method of treating mine drainage water having a pH of from 4.5 to 10, a calcium hardness greater than 100 mg/l of Ca +2 , and containing metals in solution or suspension comprising: (a) adding an oxidizing agent to the mine drainage water wherein the oxidizing agent is selected from the group consisting of peroxides, hypochlorites, permanganates, percarbonates, perborates, chromates, ozone, osmium tetroxide, sodium metaperiodate, nitric acid, nitrous acid, and persulfates, to enhance metal hydroxide precipitation; (b) precipitating and settling the metals in their hydroxide form to provide clarified water; and (c) adding a scale control agent to the clarified water to control scale deposition, wherein the scale control agent is selected from the group consisting of polymeric scale control agents, water-soluble polycarboxylates, phosphonates, organic phosphates, and sulfonates.