Processing Converter Slags with Total Utilization of All Components
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PROCESSING CONVERTER SLAGS WITH TOTAL UTILIZATION OF ALL COMPONENTS S. A. Kvyatkovskii,1 E. A. Sit’ko,2 B. M. Sukurov,3 A. S. Semenova,4 and R. S. Seisembaev5
UDC 669.333.4.184
Currently, almost all plants converted to autogenous smelting of copper-containing concentrates use flotation of converter slags (CS) while leaving 0.55–0.90% Cu in tailings that exceeds the industrial copper ore content. Most of the iron, zinc, lead and silicate components of CS enter dumps. The resultant converter slag concentrate (CSC) contains magnetite having an unfavorable effect on smelting furnace operation, and part of the copper is lost during magnetic separation of the resultant concentrate. A pyrometallurgical method for processing CS with its complete utilization is developed under laboratory conditions. Optimum parameters of the CS-based charge reduction melting are selected by crucible melting: in the first stage at 1250–1300 °C copper is extracted into metallized product and the slag composition is adjusted, from which in the second stage at 1450–1500 °C iron is reduced and recovered in cast iron. The method provides complete utilization of all slag components. 95% of the copper goes in metallized alloy, and about 0.02% Cu, 2–5% Fe, and 0.2% S remain in the slag of the second reduction stage. The copper-containing alloy is converted, and lead and zinc are transferred into sublimates. The metal-free slag obtained is suitable for use in building objects. In addition, hot slag of stage II depletion may be used as an excellent conversion flux, which is especially important when processing rich matte to blister copper, since this process occurs with an intense thermal balance. Keywords: converter slag, reduction, depleted slag, cast iron, copper-containing alloy, temperature.
With conversion of copper smelting plants to autogenic melting the problem arises of separate treatment of converter slag (CS). Almost all plants converted to autogenic melting use slag flotation [1–10]. Sometimes they float a mixture of furnace and converter slags after granulation [1] of a mixture of CS and original ore in different ratios [2]. During flotation treatment of CS cooled in ponds in the Central Ural Copper Smelting Plant (SUMZ) [2] refinement is performed to a size of –74 μm of 90–92% CS. The copper concentrate separated from converter slag (CCS) contains not less than 25% Cu, and 0.55–0.65% Cu, the main part of iron, zinc, and arsenic (≈ 70%), and half of the overall amount of lead and antimony remain in flotation tailings. In the Balkhash Copper Smelting Plant (BMZ) CS flotation tests have been conducted, cooled by a normal method (in ponds for one day) and slowly (in slag basins for ≈ 3–4 days). Slag refinement and its treatment were conducted by the SUMZ scheme. The tailing copper content was 0.57–0.6%, and extraction into to concentrate with a change in heat treatment was unchanged, i.e., 89.2–89.6% [4]. According to the normal BMZ scheme CS treatment includes two stage refinement; 60–65% of slag to a size of 74 μm. In this case copper Sa
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