Development of smelting technology of refined ferromanganese with special complex reducing agents

Abstract

The role of manganese in the production of steel is exceptionally high. A feature of the silicothermic process of obtaining refined ferromanganese is the large loss of manganese with waste slag. When waste slag is cooled, it crumbles to form a fine dust due to the polymorphic transformation of calcium orthosilicate β-Ca2SiO4 → γ-Ca2SiO4 at temperature of 450 – 470 °С with an increase in volume by 12.3 %. As the volume increases, considerable internal stresses appear inside the slag, which leads to dispersion of the slags into finely dispersed state during their cooling. This work is devoted to improving the technology of smelting refined ferromanganese grades, using special complex reducing agents. Experiments have been carried out to simulate the smelting process of refined ferromanganese in an ore-thermal refining furnace RCO-0.1 MVA using aluminosilicomanganese (ASM). The technological modes of the smelting process are established, i.e. optimal composition of charge. Charge went evenly without collapses and emissions. The stability of the current load was observed. Thus, the principal possibility of obtaining a refined ferromanganese with the use of a complex ASM alloy as a reducing agent was proved by the largelaboratory experimental melting. The use of ASM as a reducing agent, instead of ferrosilicomanganese, is due to the sufficient content of silicon and aluminum in it. The presence of chemical compounds and solid solutions of iron, silicon and aluminum in ASM should significantly reduce losses of silicon and aluminum for oxidation processes when interacting with air oxygen. And involving ASM alloy in the metallurgical redistribution, in refined ferromanganese smelting, instead of expensive ferrosilicomanganese will make it possible to obtain an alloy with high added value and with the best technological parameters, due to the presence of additional aluminum in it. The results of X-ray phase studies of slag samples show that the mineralogical components are gehlenite, dicalcium silicate and manganosite. It is noted that gelenite in them is the dominant phase, which is a solid solution, preventing the dispersion of slag. As a result of the theoretical and experimental studies, the tasks have been solved - the smelting technology of refined ferromanganese was developed and tested using a special complex reducing agent – ASM.