Use of slags from the production of manganese alloys in steelmaking

Abstract

669.18The Ural Institute of Metals has gained a great deal of experience in developing, studying, and introducing technologies for making steels from pig irons with a low content of manganese. For example, the Nizhniy Tagil Metallurgical Combine (NTMK) makes steel from a carbon-bearing low-manganese (0.02-0.05% Mn) semifinished product, the company "Severstal'" makes steel from pig iron containing 0.15-0.35% Mn, and the West Siberian Metallurgical Combine (ZSMK) makes steel from pig iron it smelts itself and pig iron transported in mixer ladles from the Kuznetsk Metallurgical Combine (KMK).The use of low-manganese pig irons in converters makes it possible to reduce or completely eliminate the use of scarce manganese ore, increase the production of pig iron [1][2][3], and reduce the production costs of pig iron and steel [1][2][3][4][5]. Studies [5] show that the quality of steel produced from low-manganese pig irons is the same as that of steel made from conversion pig iron containing more than 0.8% Mn.It has established that if no special measures are used to improve slag formation processes, the conversion of low-manganese pig iron is accompanied by an increase in the amount of metal sprayed from the furnace and a deterioration in the service conditions of the equipment. These problems are caused by an increase in the tendency of the slag to "coagulate" during the period of intensive decarbonization [5, 6]. There is also an increase in the consumption of fluorspar and a decrease in the residual content of manganese in the steel after the blow [5,[7][8][9][10], which requires the use of a larger quantity of manganese ferroalloys.Ways of alleviating or eliminating the above adverse effects have been found as a result of many years of studies. The use of recycled converter slag in liquid or solid form, changes in the blowing regime and the regime for addition of the slag-forming materials, the use of specially designed lances for blowing, and the use of different slag-forming mixtures and complex fluxes are allowing the oxygen-converter conversion of low-manganese pig irons and significantly improving the technical-economic indices of the process.Thus, the changeover to a more advanced technology for the oxygen-converter conversion of low-manganese pig irons is being delayed not only by the need to introduce a number of modifications and the lack of a universal method of fundamentally improving slag-forming processes, but also by the need to increase the unit consumption of scarce manganese-bearing ferroalloys.One promising direction is the use of manganese slags in steelmaking, particularly in the oxygen-converter conversion of low-manganese pig irons. The addition of such slags in the necessary amounts simultaneously solves the problems of increasing the efficiency of oxygen-converter steelmaking and saving manganese ferroalloys.Studies were performed on the use of ladle residues (crests) of slag from the production of silicomanganese at the Nikopol' Ferroalloys Plant to make steels at the Nizhniy Tagil combine...

Fabricação de lã de rocha a partir da escória da produção de ligas FeSiMn

“…A geração de escória para a produção da liga FeSiMn por uma única empresa situada no Brasil no ano de 2003 foi de 112 mil t [4]. Entre as aplicações para a escória, são citadas: base para a pavimentação de estradas, lastro para ferrovia [4], produção de aços com baixo teor de manganês [5,6], e na maioria das empresas produtoras a escória é descartada. Estudos sobre a avaliação ambiental da escória de ferro-manganês que foi utilizada como revestimentos de pavimentos na cidade de Salvador no estado da Bahia -Brasil, concluíram que os resíduos não podem ser classificados como inerte conforme a NBR 10004 [4].…”