Method for producing spongy iron by direct reduction of dry coal powder gasification and hot coal gas fine ore fluidized bed

Abstract

The invention discloses a method for reducing and producing sponge iron directly by a dry coal dust gasified hot coal gas fineore fluidized bed, which comprises the following steps of: a) grinding and drying the feed coal; b) spraying the dry coal dust and pure oxygen into a pressured gasification furnace; c) chilling the hot coal gas at the top of a gasification furnace to be 900 DEG C to 950 DEG C by the cooled coal gas of 30 DEG C to 80 DEG C, then removing dust, and after washing and cooling part of the coal gas to be 30 DEG C to 80 DEG C, which then returns to the top of the gasification furnace, chilling the high-temperature coal gas; d) desulfurizing the remaining coal gas which is taken as reducing gas for entering a fluidized bed reactor; and e) introducing the hot coal gas into the last level of the multilevel fluidized bed; and then the coal gas flows in the opposite direction of the iron-containing powder lot; the coal gas flows through all levels of the fluidized bed in the reverse direction and the iron-containing powder lot flows through all levels of the fluidized bed in the forward direction, and then the iron-containing powder lot and the reduced gas countercurrent contact with each other, therefore, the sponge iron is obtained by progressive reduction and carburization. The reduced gas is produced by adopting the technology of gas generation; the energy utilization rate is improved by using the sensible heat of the hot coal gas to provide the energy which is necessary in the hematite reduction; and the generated sponge iron can be used for the electrosmelting of steel directly.

Description

technical field [0001] The invention belongs to the field of metallurgy and ironmaking, and in particular relates to a method for producing sponge iron by direct reduction of dry coal powder gasification hot coal gas powder ore fluidized bed. Background technique [0002] At present, the industrial production technology of direct reduced iron can be divided into two categories: gas-based method and coal-based method. [0003] The gas-based method can be divided into two types: shaft furnace direct reduction and fluidized bed direct reduction. Among them, the shaft furnace method is represented by Midrex and HYL processes, and the sponge iron produced by these two methods accounts for more than 80% of the world's total output. The gas-based shaft furnace method has mature production technology, reliable equipment, and high productivity (volume utilization factor reaches 8-10t / m 3 · d), large single furnace output (up to 1.8 million t / a), etc., has strong competitiveness. T...

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Problems solved by technology

[0006] Chinese patent CN1275624A discloses a sponge iron production process using a Texaco coal-water slurry gas-making shaft furnace to reduce iron ore. Compared with the high specific oxygen consumption, CO+H in crude gas 2 The active ingredient is low, the gasification temperature of the hot fireplace is lower than that of the water-cooled fireplace, the life of the refractory material is short, and there is a limitation on the pulping of the raw coal

(2) Although pulverized coal can be directly used to solve the problem of using lump coal and lump coke, the shaft furnace still needs to use lump pellets, lump ore or cold-consolidated pellets, which increases the consumption required for agglomeration energy and raw material costs

The disadvantages of this method are: (1) It is impossible to get rid of the dependence on lumpy carbonaceous raw materials (lump coal or coke) and lumpy iron oxide-containing raw materials (pellets, lump ore or cold-consolidated pellets)

(4) The purified cold gas needs to be reheated to 850-1000°C to provide the energy required for shaft furnace reduction, so the cooling and reheating process reduces the energy utilization rate

Although this method can use powdered iron oxide-containing raw materials and use hot gas for direct reduction, it still cannot get rid of the dependence on lumpy carbon-containing raw materials (lump coal or coke)

In addition, due to the poor quality of the reducing gas in this method, the quality of the produced sponge iron is not high, and the sponge iron must be added to the melting and gasifier to be melted into molten iron and slagging, which also determines that this method can only be used in fixed bed gasification Way

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