Thermodynamic modeling of nickel and iron reduction from multicomponent silicate melt in bubbling process. Report 2. reducing agent – A mixture of Н 2 – Н 2 О

摘要

© 2018, National University of Science and Technology MISIS. All rights reserved. A number of technologies in ferrous and non-ferrous metallurgy are based on bubbling processes. For prediction of melting parameters including the reduction of metals from oxide melt by a reducing gas in a bubbling layer in industrial aggregates, a thermodynamic modeling technique is proposed based on calculation of the equilibrium in oxide-melt-metal-gas system. Originality of the technique is that equilibrium is determined for each unit dose of gas introduced into the working body, with the contents of oxides of metals being reduced in each subsequent design cycle equal to the equilibrium in the previous one. For the analysis NiO (1.8 ) – FeO (17.4 ) – CaO (13.5 ) – – MgO (1.9 ) – SiO 2 (58.0 ) – Al 2 O 3 (7.4 ) oxide system was taken, closely corresponding to composition of oxidized nickel ore. The ratio of Н 2 О/Н 2 in gas mixture varies between 0 and 1.0. (1823 K), amount and composition of formed metal (ferronickel), as well as the indices (the ratio of slag and metal, the degree of reduction of metals) are important in implementation of the process under commodity conditions. The increase in hydrogen consumption monotonously reduces the content of nickel oxide in the melt, while the content of iron oxide initially increases, and then decreases. When H 2 is introduced in an amount of about 50 m 3 per ton of the melt, the content of nickel oxide in it is reduced to 0.017 , and of iron oxide to 16.7 . Resulting ferronickel contains 61 Ni, ratio of slag and metal – 42 units. Further increase in H 2 consumption leads to preferential iron reduction. An increase in H 2 O/H 2 ratio worsens the results of reduction of metals from the melt: decrease in degree of reduction of nickel and iron, increase in nickel content in the alloy, and the ratio of slag and metal. However, even with a H 2 / H 2 O ratio of 1.0, which corresponds to 50 of H 2 O in the gas mixture, reduction process does not stop. For comparison, the work presents data on change in content of nickel and iron oxides, when metals are restored from similar melts with carbon monoxide. At a nickel recovery rate of 98 , indicators are close in case of using both H 2 and CO. However, to achieve them, it is required 2.5 times less hydrogen, and 1.36 times less mixture in which H 2 O/H 2 = 0.11 (H– 90 ) than carbon monoxide.