A coal-based method for rapid and deep reduction of high-density metallized pellets at low temperature

Abstract

The invention belongs to the technical field of metallurgy, and particularly relates to a coal-base low-temperature quick deep reduction method of high-density metallized pellets, which comprises the following steps: uniformly mixing iron ore powder or iron scale to be reduced with carbon powder and an adhesive, and spraying water to prepare phi8-phi20mm pellets; drying, preparing a material to be reduced from the pellets and a reducer, adding the material to be reduced into a flame-isolated rotary kiln, carrying out reduction reaction, and carrying out magnetic separation to obtain the high-grade high-density metallized pellets, of which the grade TFe is greater than or equal to 90%, etaFe is greater than or equal to 93% and the density is greater than or equal to 4.3t / m<3>. The reduction apparatus adopts a flame-isolated rotary kiln, thereby saving the energy. The material reaction is more violent, thereby greatly shortening the reaction time. The high-density metallized pellets with the density of greater than or equal to 4.3t / m<3> have the advantages of uniform particle size, high grade, simple components and trace amounts of harmful elements, and is suitable to be used instead of steel scrap, a diluter and a cooling agent for steelmaking.

Description

technical field [0001] The invention belongs to the technical field of metallurgy, and in particular relates to a coal-based low-temperature rapid deep reduction method for high-density metallized pellets. Background technique [0002] China's iron and steel industry used to vigorously develop blast furnace ironmaking, but reduced iron technology is relatively lagging behind. my country's annual output of reduced iron is 500,000 tons, accounting for less than 1.0% of the world's total reduced iron production. With the gradual increase in the proportion of high-quality steel in electric furnaces, there is a gap of more than 28 million tons of reduced iron products every year. Therefore, about 10 million tons of foreign DRI and HRI products are imported every year. As my country's coking coal reserves are increasingly scarce and environmental protection problems are becoming more and more serious, the state has introduced more relevant industrial policies to encourage the deve...

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Problems solved by technology

[0004] The density of liquid steel slag for steelmaking is generally 2.6-2.8t / m 3 , and the density of reduced iron produced by direct reduction is generally 1.8-1.9t / m 3 , the density of the mineral powder pre-pressed block after reduction is generally 2.3-2.5t / m 3 , into the steel furnace, can not sink into the slag, floating on the steel slag, it is easy to re-oxidize, unable to obtain satisfactory molten steel yield, resulting in narrow application range of reduced iron, high application cost and other factors, steel mills can not because of trace reduction The supply of iron and the frequent adjustment of the steelmaking process have led to difficulties in sales of the small reduced iron production in my country.

[0005] Existing iron reduction methods include coal-based tank type tunnel kiln method, rotary hearth furnace method, car bottom furnace method, tankless tunnel kiln method, internal combustion rotary kiln method, etc. The disadvantages of these methods are: coal-based tunnel kiln method The reduction temperature is generally 1130 ℃ ~ 1160 ℃, this temperature reflects the temperature of the roof of the tunnel kiln, and the entire section of the tunnel kiln has a temperature difference of 50 ℃ between the upper and lower temperatures, and there is a layer of 40mm reduced coal protection in the refractory tank There is a temperature difference of about 280°C between the temperature of the intermediate iron material and the outside of the tank, so the actual reduction temperature of the iron material in the refractory tank is 800-830°C, so the actual reduction temperature of the tunnel kiln method is relatively low, and the reaction is not very violent, so the reduction time Longer, the reduction time is generally 28-48h; the reduction temperature of the internal combustion rotary kiln method is generally 1220-1260°C, while the actual temperature of the material is about 950°C, and the reduction time is 6-8h, because the required reduction temperature is too high , resulting in energy consumption

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