Thermodynamic simulation of iron and nickel reduction from oxide melts

The significance of research on recovery of metals from oxide melts is primarily associated with pyrometallurgical processing of ferrous and non- ferrous metals. The main task during the processing of oxidized nickel ores is to increase the extraction of valuable metals with the required (10 – 20 %) nickel content in ferronickel and a minimum amount of impurities. The indicators achieved during the reduction of iron and nickel from oxide melt were evaluated by the thermodynamic simulation methods. Two series of calculations were carried out. In the first series, the working medium composition was changed by the amount of iron and nickel oxides at a С_FeО / С_NiО ratio equal to 10. In the second series, at a С_NiО content equal to 1.8 %, С_FeО value for С_FeО / С_NiО ratios was varied from 10 to 20. A dosed increase of CO amount in the working medium made it possible to trace the changes in compositions of oxide (С_МеО ) and metal (С_Ме ) melts, as well as the transition degrees of nickel (φ_Ni) and iron (φ_Fe) to the metal state. The С_NiO , φ_Ni = f (C₀ , V_CO ) correlation dependences are presented in form of the second-degree polynomials. The φ_Ni and φ_Fe indicators are changed with amount of introduced reducing agent, but it depends little on the initial condensed phase composition. The composition of the formed Fe – Ni alloy is affected by the content of elements in the initial melt and amount of the introduced reducing agent. Alloys are characterized by the high (65 – 90 %) nickel content. The φNi value of about 98 % was achieved with the amount of introduced CO of about 80 m³ per ton of melt. In this case, the degree of iron reduction was no more than 5 %. When the С_FeО / С_NiО ratio is 10, the nickel content in the alloy is practically independent of the content of its oxide in the initial ore melt and is close to 65 %. An increase in the С_FeО / С_NiО ratio from 10 to 20 leads to the change in С_Ni from 68.5 to 52.9 %, respectively. The data obtained are significant for substantiation of the technology for processing low-quality oxidized nickel ores with the release of the required ferronickel composition.

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