Modern condition and development prospects of alternative processes of the ferrous metallurgy

Abstract

Nowadays a significant number of alternative processes of ferrous metals production have been developed, it differs in the principles of operation, as well as the design arrangement of the aggregates. In general, "alternative" processes of ferrous metals production can be divided into 4 groups. The processes of the first group (the production of sponge iron in direct reduction units with remelting in electric arc furnaces) are based on the use of reduction gases (CO, H2 or a mixture of them) or coal for the reduction. Depending on this, they have different principles of work and design. Shaft processes of direct reduction, based on the use of reduction gases, have the dominant positions in the global production of HBI. This is due to the design simplicity of these units, the reliability of their work and the low content of harmful impurities (S, P) in the products. The principle of the processes of the second group (production of carbon semi-products in smelting reduction units with blowing in BOF) involves the reduction of iron ore with power-generating coal at temperatures of 1400-1600 °C and obtaining hot metal. The processes of this group can use as a charge partially reduced iron ore materials (Corex processes, Finex, Tecnored, etc.), as well as raw iron ore (processes Hismelt, Romelt, Ausiron). More than forty processes in various countries have been developed and tested to substitute blast furnace process. Currently, there are 7 Corex units in the world (2 - China, 4 - India, 1 - South Africa) with a total annual productivity of about 7 million tons; 3 Finex units (2 in Korea, 1 in India) with an annual productivity of about 3.5 million tons. The development of processes for the direct production of steel from iron ore (the third group) is currently focused on the processing of iron-containing waste (sludge, scale, dust iron ore) to crude steel. Examples include: the process of jet-emulsion refining, production of high carbon steel in rotary inclined furnaces or perspective direct electrolysis processes of iron ore (MOE), the development of which is at the initial stages of laboratory research. Continuous processes for the production of crude steel from hot metal (the fourth group), due to difficulties in controlling a continuous process, high consumption of refractories, low economic indexes and, most importantly, the rapid growth of ladle treatment of steel, could not compete with the LD-process and are currently hardly used. It should be said about the prospects of the considered alternative processes for the ferrous metals production. The processes of direct reduction have proven their competitiveness, the prospects of their development is determined by the need of electric steelmaking in high-quality metal charge. At the moment smelting reduction processes of ferrous metals production are not the real competitors to BF process and so far they should be considered only as an addition to it. However, if the price of metallurgical coke continues to grow, then the further spread of smelting reduction processes is possible. The processes of the third group are directed to the utilization of iron-containing metallurgical wastes and dust iron ores, but the development of majority of these processes is on its initial stages, their prospects will be determined by economic efficiency. Continuous steelmaking processes with use of hot metal as a charge could not clearly prove their superiority to the well-known steelmaking processes, at this stage their prospects are rather doubtful.