Method of regeneration of metallic chromium from slags containing chromium oxide

FIELD: converter process with use of oxygen lance.

SUBSTANCE: proposed method is used for converter processes such as AOD, MRP, AOD-L, MRP-L, CLU, ASM, Conars-Stainless steel, or vacuum processes such as VOD, SS-VOD, RH and RH with use of oxygen lance. Slag formed at the end of blowing and treatment in converter or vacuum plant is drained and removed in unreduced state; this slag is fed to electric furnace which is loaded with standard charge consisting of metal scrap and residual dust; then carbon is additionally fed and silicon if necessary; during melting, chromium oxide contained is slag is reduced by means of carbon and silicon.

EFFECT: low cost of process.

1 dwg

The invention relates to a method of regeneration of metal containing chromium from chromium oxide slag.

When widely used furnace processes, such as AOD, MRP, AOD-L, MRP-L, CLU, ASM, Conarc-Stainless steel, or vacuum processes, such as VOD, SS-VOD, RH, RH using an oxygen lance, is the principal decarburization reaction in a multicomponent system, and recovery of chromium oxide carbon is the key.

After the initial oxidation of chromium that is present in high concentrations in high-quality steels, conduct its restoration on the surface of the bubbles dissolved in the melt, the carbon in the so-called focal spot. Product recovery, metal chrome-circulate back into the melt and the carbon monoxide after diffusion into bubbles dissipate into the atmosphere of gas above the melt.

Chemical reactions proceed as follows:

The reactions take place at the next thermodynamic equilibrium:

,

and

where p is the parameter.

Due to incomplete reaction of chromium during decarburization partial amount of chromium oxide in the form of various spinel gets into the slag. The effect of recovery on subsequent decarburization is greatly reduced, since the content is the use of a restorative element, carbon, temporarily decreases. The economy of the process is based on regeneration associated thus chromium. This is usually at the end of the decarburization and process oxygen blast carry out the restoration of slag having a high affinity of silicon in the form of FeSi.

The basis of the invention is to create a simpler and therefore more cost-effective way.

This problem is solved due to the fact that the slag formed in the end of the process of purging or processing in the Converter or vacuum installation, drain or divert without recovery, and this slag is sent to the furnace, loaded the rest of the usual manufacture, consisting of scrap metal and, if necessary, residual dust, impose additional carbon and optionally silicon, and during the melt contained in the slag, chromium oxide, carbon and silicon directly restore in chrome metal.

Traditional surgery for slag reduction is not carried out. The slag is saturated by a high content of chromium oxide and manganese oxide-iron and formed, for example, after oxygen blast, is separated from the metal in unrestored form, i.e. merge or take away from the bucket and served in the upstream furnace. Through carbon additives and silicon contained in the normally loaded in the furnace IU is allalone, containing, if necessary, residual dust, there is a direct recovery of slag. Thus, chromium oxide restore in the electric furnace instead of have one of her installations and regenerate the metal chromium.

The reduction proceeds according to the following scheme:

In the electric furnace under atmospheric conditions is the direct recovery of chromium oxide with carbon monoxide and certain amounts of silicon, and this reaction proceeds as follows:

or in the case of silicon:

Resubmission of slag in altropico can be done immediately after each treatment, but also after various processing operations in the form of the accumulated amount.

Depending on the technology, this can be arranged at optimal cost and optimal energy consumption. When implementing the method does not matter whether the slag in solid, liquid or intermediate state. This only affects the duration of the melt in the furnace.

In General, through such procedures are achieved following the economic and technological advantages:

- reduced the total melt treatment for 15-20 minutes depending the on the type of technology

- reduction of FeSi

- reduction of the slag-forming additives

- high metal extraction

- increased service life of the refractory material,

- increased service life of the tuyeres and the purge nozzles,

- improved energy balance Converter or vacuum installation

- a higher degree of purity of the metal,

- failure or sudden drop in the amount of slag protection zones for converters and Kovshov.

Using the on shapes block diagram implementing the method further explains its implementation, and figure 1 is presented a three-stage process, in figures 2 and 3 presents a two-step process.

Method of regeneration of metal containing chromium from chromium oxide slag from BOF processes, such as D, MRP, AOD-L, MRP-L, CLU, ASM, Conarc-Stainless steel, or vacuum processes, such as VOD, SS-VOD, RH, RH using an oxygen lance, characterized in that the slag formed in the end of the process of purging or processing in the Converter or vacuum installation, drained and absorbed in unrestored form the slag fed into the furnace, which in the rest of the load of conventional manufacture, consisting of scrap metal and, if necessary, residual dust, additionally serves the carbon and optionally silicon, and in time the I melt contained in the slag chromium oxide restore using carbon and silicon directly in chrome metal.