Abstract: A method for the removal of heavy metal ions from an aqueous solution which comprises the steps of admixing an aqueous slurry of FeS.sub.2 with a heavy metal ion bearing aqueous solution at a pH above 7, preferably 8-12, the slurry providing at least the stoichiometric amount of FeS.sub.2, preferably 2 to 6 times the stoichiometric amount of FeS.sub.2, for precipitating the heavy metal ions from the solution as sulfides and separating the precipitated sulfides from the aqueous solution. Desirably, a portion of the heavy metal ions are precipitated from the solution as heavy metal hydroxides and the precipitated hydroxides are separated from the solution prior to admixing the solution with the FeS.sub.2 slurry.