Research on Industrial Microwave Steelmaking Technology

As a new steelmaking technology, microwave equipment steelmaking has a prominent significance in promoting the development and transformation of world metallurgy. In microwave steelmaking, iron ore is crushed, milled and concentrated by traditional methods, and then mixed with coal and limestone. Here coal is used as reductant, and the auxiliary heat source is formed by exothermic oxidation reaction, while limestone is used as flux. Compared with traditional steelmaking, microwave steelmaking uses coal with abundant resources rather than coke with high price. Under the condition of 1000 C and air, coal reacts with oxygen in the air to produce CO2. In the presence of sufficient coal, only CO exists in the furnace. Iron ore pellets directly generate steel in CO atmosphere, thus eliminating the step of "oxygen injection and carbon removal". The control of reaction temperature is also easy to accomplish through arc furnace. The whole steelmaking process not only saves time, but also saves energy. According to calculation, compared with traditional steelmaking, it can save 48.5% energy. The blast furnace ironmaking technology of

is still the most basic steelmaking technology after continuous improvement. After the iron ore sintering pellets, coke and limestone are loaded into the blast furnace, high-speed hot air is injected into the blast furnace. Some of the coke is consumed to produce CO and heat, and the iron ore sintering pellets are reduced to iron by CO. The reduced molten iron is then sent to the oxygen top-blown converter (BOF), where pure oxygen is blown into the molten iron to remove carbon and obtain steel. As a technological innovation, microwave assisted EAF steelmaking is accomplished by combining microwave, arc and exothermic heating. This technology can directly obtain molten steel from raw pellets consisting of concentrated iron ore, coal and flux without coking, sintering, blast furnace iron smelting and oxygen blowing. This technology can make full use of the characteristics of microwave bulk heating, energy efficient absorption and high-speed chemical reaction. In general, the thermal conductivity of non-conductive materials is very poor, and external heating methods often fail to effectively heat them. This is especially true for concentrated iron oxide powder material, which is a basic problem in traditional steelmaking. Microwave heating has a very high heating efficiency. Microwave heating is more effective for powder materials, including agglomerated powder materials. Its heating efficiency is as high as 90%~95%. The results of two scientists'experiments show that the temperature of magnetite can rise to 1000 C in one minute under microwave heating, which solves the basic heat transfer problem in steelmaking.