Improving quality of sulfate-containing acidic waters, e.g. opencasting mining residual lakes, by by two-stage neutralization using sodium hydroxide and calcined dolomite or sodium carbonate

摘要

A method for improving the quality of sulfate-containing acidic waters (I), by increasing the pH value and buffering action, involves: (i) initially neutralizing (I) and/or water having an acidic inflow (having pH less than 5.5 and sulfate content more than 400 mg/l) to pH 4.3-7.0 by volume- and acid potential-dependent addition of sodium hydroxide; then (ii) adjusting the pH and buffering capacity (Ks 4.3) to predetermined values in the ranges 5.5-8.2 and 0.2-32 mM respectively, at least partially by treatment at pH 4.3-8.2 with calcined dolomite (of magnesium oxide content more than 15% and particle size less than 2 mm) or sodium carbonate.