CARBOTHERMIC REDUCTION OF COMPLEX SULFIDES CONTAINING ARSENIC AND ANTIMONY .2. CARBOTHERMIC REDUCTION OF COPPER ARSENIC SULFIDES

The lime-enhanced carbothermic reduction of synthesized enargite (Cu3A sS4) and tennantite (Cu12As4S13) has been investigated in the temperat ure range 700-1000-degrees-C. Reduction mechanisms were determined by analysing rate data obtained by thermogravimetry and by optical and el ectron microscopy and X-ray diffraction analysis of the reaction produ cts. The reduction of Cu3AsS4 and Cu12As4S13 results in the formation of copper arsenide (Cu3As), metallic copper and calcium sulphide. At 1 000-degrees-C reduction is complete after about 40 min, but it does no t go to completion at lower temperatures. The lattice parameter of the metallic copper phase obtained by carbothermic reduction is 3.641 ang strom, indicating a dissolution of 7.8 wt% arsenic in the metallic cop per product. This represents the maximum level of arsenic solubility i n copper.