Efficient rotary hearth furnace direct reduction treatment process for zinc-containing dust and sludge in iron and steel plant

Abstract

The invention discloses an efficient rotary hearth furnace direct reduction treatment process for zinc-containing dust and sludge in an iron and steel plant. The process comprises the steps of carrying out raw material treatment, carrying out burdening, carrying out mixing, carrying out forming, carrying out material drying, carrying out roasting reduction, carrying out flue gas treatment and carrying out finished product cooling. According to the process, CO and H2 are used as reducing agents, and H2 is derived from low-rank coal pyrolysis. The process has the beneficial effects that iron oxide is reduced into metal iron through hydrocarbon combined reduction, zinc oxide is reduced into metal zinc and then volatilized, oxidized and collected, the metallization ratio of a product can reach more than 90%, the metallization ratio is increased by 30% compared with that of an existing product, and the dezincification rate is larger than 95%. A hydrocarbon combined reduction technology is adopted, the reduction temperature is low, and the energy consumption is low. The reduction temperature of a traditional rotary hearth furnace is 1250-1350 DEG C, while the reduction temperature of the process is 800-1230 DEG C, so that the application range is wider. According to the process, reduction coal is added in the burdening stage and the deep reduction stage respectively, the reducing atmosphere of later hydrogen reduction is enhanced, the reduction efficiency and the metallization ratio are improved, meanwhile, the reduction coal in the process adopts low-rank coal instead of anthracite, and the cost is low.

Description

technical field [0001] The invention relates to the technical field of metallurgy and mineral engineering, in particular to a high-efficiency rotary hearth furnace direct reduction treatment process for zinc-containing dust and sludge in iron and steel plants. Background technique [0002] Dust in iron and steel plants is generally 8% to 12% of steel production, and zinc-containing dust accounts for 20% to 30% of the total dust. At present, there are about four domestic methods for dealing with zinc-containing dust: (1) Sintering method. The problem of returning the dust to sintering is that with the continuous recycling of zinc-containing dust, the zinc content in the dust will become higher and higher, and the cyclic enrichment of zinc will affect the smooth operation and life of the blast furnace. (2) Mineral dressing method. Relatively simple process, low operating cost, easy to implement, but the dezincification rate is not high, from the perspective of zinc extractio...

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Problems solved by technology

The problem of returning the dust to sintering is that with the continuous recycling of zinc-containing dust, the zinc content in the dust will become higher and higher, and the cyclic enrichment of zinc will affect the smooth operation and life of the blast furnace

Compared with the traditional carbon reduction process, the hydrocarbon combined reduction process needs to consume a large amount of H2. The current large-scale hydrogen production methods mainly include: hydrogen production by electrolysis of water, hydrogen production by natural gas cracking, hydrogen production by petroleum gasification and cracking, and coal gasification production. Hydrogen, coke oven gas hydrogen production, etc., because of the high production cost of the above hydrogen production processes, there is no large-scale promotion and application. Therefore, the ability to supply hydrogen on a large scale is the premise and basis for the development of the combined hydrocarbon reduction process.

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