Analysis of the use of magnesium-containing additives in the charge of iron flux in order to reduce CO2 emissions

Abstract

The growing requirements for the quality of finished steel products oblige to obtain steel with a low content of harmful impurities, especially sulfur. The main charge for steel production in the conditions of JSC EVRAZ NTMK is vanadium iron, the external desulfurization of which leads to large losses of valuable vanadium. Therefore, the smelting of iron with a low sulfur content is an urgent task. The main way to reduce sulfur in iron is to increase the basicity of the slag (B2), but MgO is the best desulfurizer. The paper evaluates the effectiveness of the use of various magnesium-containing materials in the conditions of the blast-furnace stage of JSC EVRAZ NTMK, taking into account CO2 emissions. The possibility of replacing limestone in the iron flux charge with dolomite, as well as with steel converter slag, is considered. Both materials will increase the proportion of MgO in blast-furnace slag, however, the use of dolomite is accompanied by a two-fold increase in CO2 emissions compared to limestone. Converter steel slag (CSS) does not contain carbonates, thus eliminating the formation of CO2 during the limestone decomposition. An additional advantage of CSS is its high content of valuable vanadium and manganese. The effect of an increase in MgO in slag on its melting point is considered. It has been established that an increase in the proportion of MgO to 14% will not cause difficulties in the processing of blast-furnace smelting products and will reduce the sulfur content in iron and the formation of titanium carbides and carbonitrides.