Abstract

Acid leaching has been developed for the extraction of chromium, iron, magnesium and other metals from industrial solid wastes. Leather industries which promote hide stabilization by chrome tanning are a major source of chromium sludge. In the method, sulphuric acid was used to extract chromium and the leach liquor was analyzed. Different influences, such as dosage, volume ratio, temperature, reaction time and mode of action were investigated. Under the optimum conditions, the maximum extraction rate was up to 70%. The samples (before and after acid leaching) were compared by scanning electron microscope (SEM) and the content of each element was determined and analyzed by energy disperse spectrometer (EDS). SEM results display large changes in the surface appearance. The surface area of the sludge is greatly increased. Compared with other methods, acid leaching is simpler and economical and has good potential.