The Thermodynamic Evaluation of the Interphase Distribution of Elements in the Chromium and Nickel-containing System


The results of thermodynamic modeling of the process of element reducing from a chrome-containing ore-lime melt by silicon ferronickel depending on temperature are presented in this article. The consumption of reducing agent is equal to 105% of the required stoichiometric amount of reducing agent for complete reduction of iron and chromium in the temperature range of 1300–2200∘С. The chemical composition of the ore-lime melt is, wt. %: 24 Cr2O3; 13 FeO; 42 CaO; 3 SiO2; 9 MgO; 9 Al2O3 and of silicon ferronickel is, wt. %: 65 Si; 28 Fe; 7 Ni. The HSC Chemistry 6.12 software package developed by Outokumpu Research Oy (Finland) is used. The composition of oxide Cr2O3-FeO-CaO-SiO2-MgO-Al2O3 and metallic Fe-Si-Ni-Cr systems are calculated using the module «Equilibrium Compositions». A gas phase pressure is 1 atm. The gas phase of the system contains 2,24 m3 N2. It is established that the increase in the process temperature from 1300 to 2200∘С contributes to reducing of the degree of chromium reduction from 98,9 to 69,8%. The degree of reduction of aluminum and magnesium increases from 0,2 to 8,7% and from 0,007 to 2,5% respectively, and the degree of reduction of iron doesn’t change over the entire temperature range and is equal to 100%. The chromium content in the metallic phase decreases with increasing temperature from 51,7 to 41% and the residual CrO content in the slag increases. The chemical composition of the alloy is, wt. %: 50,41 Cr; 44,06 Fe; 1,97 Si; 3,3 Ni; 0,035 Mg; 0,21 Al; 0,005 P at the temperature of 1700∘С. The results of thermodynamic modeling can be used for laboratory experiments and technological calculations for obtaining chromium and nickel-containing complex ferroalloys suitable for smelting stainless steel grades.

Keywords: thermodynamics, system, interphase distribution, reducing agent consumption, degree of recovery, temperature, chromium, nickel

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