Thermodynamic simulation of iron and nickel reduction from oxide melts

Abstract

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 Ме О ) 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 ( C 0 , 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 φ Ni value of about 98 % was achieved with the amount of introduced CO of about 80 m 3 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.