Reduction ironmaking process of bottom heating type fixed furnace hearth

Abstract

The invention discloses a reduction ironmaking process of a bottom heating type fixed furnace hearth. A furnace is arranged below the furnace hearth; a furnace cover for sealing a material layer is arranged above the furnace hearth; heat is generated in the furnace through the fuel combustion, and is transferred and diffused to the material layer of the furnace hearth; and the redox reaction is generated on the material layer to generate sponge iron. The arrangement mode of the material layer is as follows: molded coals are directly arranged on the furnace hearth; and then, iron fine powder pellets are arranged on the molded coals. The diameters of the iron fine powder pellets are 10-30 mm; and the average size of the molded coals is 1.1-1.5 timers of that of the iron fine powder pellets. The carbon-oxygen mol ratio of the iron fine powder pellets is 1.0-1.5. The process separates a direct reduction area from a combustion area, so that the atmosphere in a reduction furnace is controllable, the secondary oxidation of the reduced sponge iron is prevented, and the high-quality sponge iron is produced. The reaction dynamic conditions are excellent; the reaction speed is quick; the quality of the reduced iron is good; and the problem of easy bonding of self-reduced pellets on the furnace hearth at the high temperature is overcome.

Description

technical field [0001] The invention belongs to the field of metallurgical industry, and relates to a direct reduction iron production method, in particular to a bottom-heating fixed hearth reduction ironmaking process. Background technique [0002] Direct reduced iron (DRI), also known as sponge iron, is formed by reducing iron ore, iron concentrate or iron-containing raw materials with natural gas or non-coking coal as a reducing agent. Depending on the reducing agent, the chemical composition of the produced DRI is also different. As smelting steel types have stricter requirements on residual elements, especially steel products such as nuclear power, hydrogenation, and power stations, the use of ordinary returned scrap steel and purchased scrap steel for smelting can no longer meet the product’s requirements for residual elements. Due to its very low content of impurity elements, direct reduced iron is often used to replace part of scrap steel in steelmaking to solve the...

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Problems solved by technology

Due to the strict requirements on raw materials and fuels, the high investment and operating costs per unit capacity, the difficulty in stable operation, and the small production scale (maximum 150,000 t / year), it is difficult to become the main process for the development of direct reduced iron in my country

[0006] Rotary hearth furnaces have achieved industrial production in the treatment of dust containing Fe, Zn, Cr, and Ni in iron and steel plants. The disadvantages are that the sponge iron (DRI) gangue and sulfur content are high, which leads to an increase in the amount of steelmaking slag in the electric furnace and electrode consumption. Difficult to be directly used in the production of direct reduced iron for steelmaking

Secondly, the rotary hearth furnace adopts the open flame heating method to heat the charge. Since the fuel combustion is an oxidizing atmosphere, and the reduction of iron oxides requires a reducing atmosphere, the open flame heating method usually has the difficulty of controlling the furnace atmosphere, and the reduced products are easy to be secondary. The problem of oxidation affects the final quality of sponge iron

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