THERMODYNAMIC MODELING OF THE PROCESS OF METAL DESULPHURATION BY BORON CONTAINING SLAGS OF THE СaО–SiO2 –MgO–Al2 O3 –B2 O3 SYSTEM

Thermodynamic modeling of process of metal desulphurization with boron-containing slags of the СаО – SiO2  – MgO – Al2 O3  – B2 O3 system was carried out using HSC 6.1 Chemistry (Outokumpu) software. Influence of process temperature (1500-1700 °С), basicity of slag (2  –  5) and content of В2 О3 (1  –  4  %) on desulphurization of steel was studied. It was established that increase in temperature of metal desulphurization process from 1500  °C to 1700  °C helps to reduce sulfur content in the studied range of slag basicity. At temperature of 1600  °C, sulfur content in metal was 0.0052  % for slag basicity of 2, and at 1650  °C its concentration was 0.0048  %. Increase in basicity of slag from 2 to 5 had encouraging effect on the degree of metal desulfurization, increasing it from 80.7 to 98.7  %, respectively, at temperature of 1600  °C. At the same time, an increase in В2 О3 concentration in slag had a negative effect on the process of metal desulfurization. Slag with basicity of 2, containing 1 and 4  % of В2 О3 , allowed to obtain the amount of sulfur in metal, 0.0052  % and 0.0098  % respectively at a temperature of 1600  °C, and slag with basicity of 5 with the same content of В2 О3 at the same temperature provided the amount of sulfur in metal 0.00036 and 0.00088  %, respectively. It should be noted that more favorable conditions for metal desulphurization provided the slag without В2 О3 oxide comparing with the boron containing one. Slag with basicity of 2 and 5 without В2 О3 according to the results of thermodynamic modeling allowed to obtain metal at temperature of 1600  °C with sulfur content of 0.0039 and 0.00019  %, respectively. Results of calculation of thermodynamic modeling of metal desulphurization process with boron-containing slags of СаО – SiO2  – MgO – Al2 O3  – B2 O3 system with basicity of 2  –  5 in temperature range of 1500  –  1700  °C correlate with experimental data and can apply to improving technology of steel desulphurization with boron-containing slags in steelmaking industry. 

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