The paper presents a technological concept of limiting the concentrations of SO₄^2- ions in discharge waters from ore mines. It is based on authors’ research performed for waters of Bytom trough, discharged on the surface in the volume of 30 thousand m³/day. The method applied has been based on transferring SO₄^2- ions into a slightly soluble alkaline calcium-aluminium sulphate. The technological concept assumes the following: - use of the waste from anodic oxidation of aluminium (AUA) as a basic reagent in the process, - conducting the reaction with AUA in a heterogeneous system, - economic utilisation of post-process slime. The results of laboratory tests indicate that the process will be feasible in practical use, and water will reach, after treatment, the quality corresponding with, at least, class III purity of surface waters.