Technical and Economical Substantiation of the Technology of Joint Pyrometallurgical Processing of Oxidized Nickel Ores and Sulfide Copper Ores

Abstract

The technological scheme of processing of nickel and copper ores from the Urals deposits is substantiated, including calcination of oxidized nickel ore with limestone, partial oxidative roasting of sulfide copper ore, blending of calcines with coke, and melting of charge to obtain copper-nickel matte. The implementation of the scheme will increase the complexity of possible uses of raw materials and ensure a high environmental protection level. A feasibility study was carried out for the organization of industrial enterprise, which entailed the joint processing of oxidized nickel ores and sulfide copper ores with a capacity of 700,000 tons per year of a mixture of initial ores, including 400,000 tonnes of nickel ore and 300,000 tonnes of copper ore (dry weight). Finished products are: copper-nickel matte, containing not less than, wt.%: 3.3 Cu, 4.7 Ni, 0.6 Co, 1.5 g/t Au, 2.6 g/t Ag; granular slag containing, wt.%: 0.01–0.02 Ni, 0.01–0.02 Cu, 0.01–0.06 Co, 13–16 Fe, 44–50 SiO2, 13–14 MgO, 4–5 Al 2O3, 9–11 CaO; and technical grade sulfuric acid (mass fraction of monohydrate not less than 92.5 %). The planned enterprise is expected to produce the following annual volumes of finished products (not less than): 94,900 tonnes of matte; 512,300 tonnes of granular slag; and 235,500 tonnes of technical grade sulfuric acid. The estimated period of project implementation is 13 years. The total amount of investment costs is 1407 million roubles, current costs for the annual production program are 3820 million roubles. The financial results of the investment project are characterized by the following indicators: net profit is 5,735.5 million roubles, net discounted income is 1546.6 million roubles, the profitability index of discounted investments is 2.1, the internal rate of return is 36.4 %, and the discounted payback period is 5.5 years. The results indicate the viability and economic efficiency of the project.