Distribution Disciplines and Cause of Harmful Elements in Copper Tailing Sand

摘要

Measure content of fresh tailing sand in a certain skarn type copper mine selection tailing sand warehouse, lead, cadmium, arsenic, nickel and zinc elements, etc in old tailing sand by ICP-AES. Carry out eluviations test of tailing sand and leaching test of tailing sand by horizontal vibration method and Sulphuric-Nitric acid method respectively. Discuss with phase constitution of harmful elements such as arsenic in tailing sand by XRD analysis chromatogram of tailing sand. Compare with content analysis result and mineral constitution of related elements in raw mine on the basis. Research migration and distribution disciplines of associated harmful elements in raw mine to tailing sand by floatation. Test result shows that arsenic, zinc, cadmium and lead elements in raw mine deeply concentrated in tailing sand after mine selection. Percentage is 96.89%, 92.0%, 91.65% and 41.12% respectively. Main existence form of As in tailing sand is FeAsS (arsenopyrite). It intergrowth with pyrite (FeS_2); Zn mainly exists in a ZnS (sphalerite) form. Pb, Cd and As have migration trend from upstream to downstream of tailing sand warehouse and from shallow layer to deep layer. Dissolution rate of Cd, Cu, Zn, Cr and Pb under eluviation and weak acid leaching conditions is lower. However, they have release trend under acid conditions. Arsenic element is special as follows: It is undetected in various points during Sulphuric-Nitric digestion. However, tiny detection of fresh surface layer and deposit layer out of old tailing sand by horizontal vibration method prompts stability of arsenic tailing sand FeAsS and alarm of leaching activity under alkaline conditions. Cause of arsenic tailing sand FeAsS is that it is brought by raw mine without large destruction to FeAsS during mine selection process.