Two-stage decontamination process of mine water containing arsenic and iron ions

摘要

In the present invention, there is disclosed a decontamination process of mine water containing arsenic and iron ions wherein purification takes place in two stages. In the first stage, a portion of Fee2+ ions is precipitated at a pH ranging from 2 to 5 in the form of iron hydroxide oxides. Arsenic, in the form of arsenates (AsOi4e3-) is immediately quantitatively adsorbed on the surface of the precipitate being just formed. Other ions remain dissolved in the solution. After separation of the precipitate (by decanting and/or filtration), all the other ions are precipitated in the second stage and at pH 2 to 8.5, to thereby decontaminating the mine water. Waste precipitate is so separated into a "toxic" fraction containing arsenic and a non-toxic remainder.