Recovery of chromium from sludge formed after neutralisation of chromic wastewater

This paper describes chromium recovery from sludge generated while neutralising chromic wastewater. Chromium(III) hydroxide is the main component of these sludges. The recovery method is based on the transformation of chromium(III) hydroxide to chromium(VI) and was developed in our department. The method includes precipitation of the chromium(III) hydroxide and its dissolution, oxidation of chromium (III) to chromium(VI), solvent extraction and reextraction of chromium(VI). The chromium recovery yield of each procedure stage was in the range of 92 to 99%. Overall chromium recovery yield was about 90%.