Method for preparing clean steel by coal gas direct reduction one-step method

Abstract

The invention discloses a method for preparing clean steel by a coal gas direct reduction one-step method. Low-coal-rank coal is pyrolyzed to tar, pyrolyzed coal gas and sponge-shaped fixed carbon at a medium temperature; the sponge-shaped fixed carbon and water vapor are reacted to prepare reducing gas; the reducing gas is introduced in iron pellets or lump ores; iron therein is selectively reduced to obtain pure sponge iron; the pure sponge iron is filled in an electric furnace for smelting to obtain pure liquid-state steel; and meanwhile, the pyrolyzed coal gas is used as heating energy for pyrolysis of the low-coal-rank coal, gasifying reaction of the sponge-shaped fixed carbon and selective gas base direct reduction of the iron pellets or lump ores. The method extracts the tar and the pyrolyzed coal gas in the low-coal-rank coal to a greater extent, and prepares the reducing gas by the sponge-shaped fixed carbon to serve as by-products in the whole process; the energy cost in the whole smelting process is almost zero; and in the selective reducing process, only iron is reduced, and other elements are not reduced, so that the foundation is laid for preparation of clean steel, the oxidation period and the reducing period in the smelting procedure of a traditional electric furnace are synchronously disappeared, and the clean steel is obtained by a simpler flow.

Description

technical field [0001] The invention belongs to the technical field of smelting reduction ironmaking, and relates to a process method for smelting metallic iron through direct reduction of coal-to-gas based on low-rank coal. Background technique [0002] The "blast furnace-converter" process is currently the most important iron and steel metallurgical process in the world. In this process, coke is used as the energy source and reducing agent required for the reduction reaction, and the iron oxide ore is reduced to make iron. While obtaining iron, elements such as Si, P, and Mn in the iron oxide ore are excessively reduced, and C is also in the iron oxide ore. Saturated and dissolved in molten iron. Then the molten iron obtained from the blast furnace is added to the converter for oxygen-blowing steelmaking. Due to the previous excessive reduction, 30-50Nm per ton of steel needs to be consumed 3 About 50Kg of oxygen and about 50Kg of lime, although most of the Si, P, Mn and...

AI Technical Summary

Problems solved by technology

The SL-RN process uses coal as the reducing agent, and can obtain a sponge with a metallization rate of about 93%. However, the problem of ring formation has been plagued by the development of this process. In addition, low efficiency, slow reduction speed, and high energy consumption also limit this process. further development of the process

[0010] 2) The tunnel kiln production process is characterized by easy handling of raw materials and fuel, easy control of the production process, stable equipment operation, and uniform product quality. It is mainly used to produce high-purity iron powder, but the tunnel kiln process has high coal consumption, short tank life, and high labor intensity. , long smelting cycle and poor economies of scale, etc., limit that this process will not be the inheritance of the new ironmaking process after all.

Therefore, none of them can be compared with the currently commonly used "blast furnace-converter" process in terms of comprehensiveness.

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