Assessment of efficiency of the use of Bakal siderites in blast furnace smelting

Abstract

Metallurgical plants in the Urals are experiencing a shortage of iron ore raw materials, which is compensated by the use of materials imported from Central Russia, the Kola Peninsula and Kazakhstan. Replacing them with the local raw materials would increase the competitiveness of metal produced in the Urals, so the question of assessing the possibility of replacing imported raw materials with local ones is very relevant. Such raw materials could be siderite ores from the Bakal deposit. They are not in demand among metallurgists because of their low iron content and high magnesium content. Calculations of blast furnace smelting made by means of balance logical-statistical model showed that additions of annealed and metallized concentrates improve performance. However, with increasing siderites in the charge, content of magnesium oxide in the slag increases, which affects its viscosity and makes it difficult or impossible to smelt using more than 20 % of siderites. It was proposed to use boron oxide to liquefy the slag. Thermodynamic modeling was used to assess the effect of adding 1 – 3 % B2O3 to the charge on chemical composition of the slag and distribution of boron between the metal and oxide phases. It was shown that in the melting process, boron is recovered from the slag phase and partially transferred to the metal. This leads to a decrease in B2O3 content in the final slag. Comparative analysis of the calculated and experimental data shows a close content of boron in the metal, determined theoretically and experimentally. It should be taken into account when calculating the charge. According to the calculations, the main reducing agent of boron is silicon, and the experimental data shows that it is carbon.