More metal, less waste
The first trials of the new leaching plant at Rönnskär began during the fall of 2020. Construction has been in progress for more than two years, and once in full operation, the plant will handle 45 ktonnes of residual material from intermediate storage and current production processes every year. One part of the plant comprises an infeed conveyor and pre-treatment where the residual material is homogenized, before water is added to form a slurry. The slurry is leached in sulfuric acid before passing through a filter press where pellets containing lead sulfate are produced. The impurities are then removed from the leachate. Copper and zinc sulfates are crystallized from the purified leachate. Along with lead sulfates, these are used in Rönnskär’s production processes. The leaching process reduces the volume of material deposited as waste in the underground repository by 80%.
Production will be ramped up in 2021 and existing residual material at Rönnskär
is scheduled to be processed by 2029. Around 10 km of cable ladders, 15 km
of cable, 10 km of steel pipes and 5 km of plastic pipes have been installed in the
leachate plant. The investment totaled SEK 750 m.