Thermodynamic modeling of cobalt and nickel reduction using hydrometallurgical enrichment concentrates for steel alloying

Abstract

The article provides studies on reduction processes in model thermodynamic systems and processes of nickel reduction from nickel concentrate and cobalt and nickel from cobalt-nickel concentrate. Concentrates are obtained during hydrometallurgical enrichment of polymetallic manganese-containing ores of the Kemerovo region – Kuzbass. By thermodynamic modeling using TERRA software complex, it was determined that nickel can be completely reduced from oxide in the NiO – C system at a carbon consumption of 0.08 kg/kg NiO, and at a carbon consumption of 0.15 kg/kg NiO ‒ in the NiO – Fe2O3 – C system. It was found that cobalt reduction in the CoO – C system begins at a temperature of about 513 K at any carbon consumption. With a further increase in temperature, the reduction process depends only on consumption of the reducing agent. From the obtained thermodynamic modeling data, it follows that cobalt reduction from the cobalt-nickel concentrate begins at a temperature of about 513 K and subsequently depends slightly on temperature. The extraction of cobalt increases with the amount of reducing agent at temperatures up to 553 K, then remains constant up to 1473 K temperature. Nickel reduction takes place at a temperature above 473 K. The degree of nickel reduction slightly depends on the temperature and amount of reducing agent at consumption of the latter over 0.02 kg/kg of concentrate. Laboratory studies showed that during the melting period, nickel can be reduced from its oxide almost completely with solid carbon, since nickel has less sensitivity to oxygen than iron. Theoretical and experimental studies of steel direct alloying showed that it is advisable to use a solid phase process in reduction of nickel and cobalt. Nickel concentrate and cobalt-nickel concentrate during steel smelting in an electric furnace is advisable to be introduced into charge in the form of mixtures pelletized with a carbonaceous reducing agent.