Column experiments investigated the stabilization of waste rock from Ljusnarsberg mine in Kopparberg, Sweden. In order to inhibit the generation of acidic leachate from the waste rock, biosludge and a Ca carbonate – rich residue from the paper industry were mixed with the sulfidic mine waste. The results of the column experiments indicate that the stabilization of the waste rock with the reactive amendments succeeded in maintaining a near – neutral pH in the waste rock leachate, compared to a pH 3 leachate from untreated waste rock. Copper and Zn concentrations in leachate from the untreated waste exceeded 100 mg/L, while these metals were detected at concentrations less than 0.1 and 1 mg/L, respectively, in the leachate from the treated wastes. This study indicates that the stabilization of acid – generating waste rock with biosludge and Ca carbonate residues is effective in preventing the generation of acid mine drainage; the treatment is expected to continue until the reactive amendments are exhausted.