Assessment of environmental toxicity of ancient pyrometallurgical slag treated by electrokinetic removal technology

Ancient pyrometallurgical zinc generated large amounts of slag. Natural leaching from ancient pyrometallurgical zinc sites has contaminated the soil closed to the deposits. In this paper, total analysis and x-ray diffraction analysis were adopted to investigate the basic characteristics of the ancient pyrometallurgical slag. The results showed that the heavy metal content in slag was high. The content of zinc was up to 109240 mg/kg. The main phases in slag were silicate and oxide. Extraction toxicity identification was used to assess the environmental toxicity before and after the enhanced electrokinetic removal technology with cation exchange membrane. The decrease of environmental toxicity was rather obvious, though the extraction quantity of zinc was still above the “Identification standard for hazardous wastes”. In order to further decrease the environmental toxicity of ancient pyrometallurgical slag, some effective means still had to carry out to improve the electrokinetic removal technology.