SU1266571A1 - Method of processing slags of low-carbon ferrochrome - Google Patents

Abstract

The invention relates to ferrous metallurgy, in particular, to the processing of disintegrating slags from the production of low carbon ferrochrome. The aim of the invention is to reduce metal losses with a non-magnetic product and to improve the quality of the magnetic product. The method consists in that the slag is first screened, then the fraction up to 20 mm is additionally treated for 10-15 minutes in an air cooled flow with material moving in suspension to a temperature of -60 ° C. After that, the material is subjected to air separation in the upward flow and the dust-free material is subjected to magnetic separation. 2 tab. "with

Description

1HE

05 О5 СП

The invention relates to ferrous metallurgy, namely to the production of ferroalloys, and can be used to process decaying slags, in particular the production of low-carbon ferrochrome.

The aim of the invention is to reduce metal losses with a non-magnetic product and to improve the quality of the magnetic product. The cooling and disintegration of slag from low carbon ferrochromium is proceeding slowly due to its thermal insulation, their properties of decomposition products. The hot pieces of undissolved slag inside the decay products can remain in this state for many hours and even sugok. Air-mechanical mixing of the slag accelerates the processes of its cooling and disintegration. It has been established that with the active mutual movement of non-dissolved slag particles and decomposition products in an air-mechanical cooling flow, the slag decomposition processes are almost complete in 12-15 minutes. Slag disintegration in the air-mechanical cooling flow is most intense in the first minutes (Table 1). At the same time, the air flow rate should ensure that particles of decomposition products soar, the limiting particle size of which for slags of low-carbon ferrochrome is usually no more than 0.4 mm.

The almost complete completion of the slag decomposition provides maximum opening of the metal beads that were previously in non-dissolved slag particles. Such material after air separation (dedusting) in an upward air flow is effectively separated in magnetic separators.

The analysis of the operation of the separation equipment according to the prototype method and the proposed method showed a decrease in the efficiency of metal extraction from slag in cases of increased temperature of the material entering the magnetic separation. In order to study the effect of the temperature of the separated slag on the metal extraction from it, special tests were carried out in the winter time (Table 2).

It has been found that when the slag temperature is above 60 ° C, the efficiency of magnetic separation decreases significantly, which leads to a deterioration in metal recovery. When the slag is cooled down to 80 ° C and below, the metal recovery increases and stabilizes, practically unchanged up to 0 ° C. At negative temperatures, separation becomes again less effective due to the freezing of particles of the material being separated to each other, to the conveyor belt and the separator drum.

The method is carried out as follows.

The slag was processed to produce low carbon ferrochrome. For

Comparison of the processing indices according to the proposed and known methods. The chemical composition of the initial slag in both cases is assumed the same, May. %:

49.5

27.9

3.5

12.2

6.5

0.4

The change in the content of the fraction — 0.4 mm in the slag during its processing in the air-mechanical flow is presented in Table. one.

The temperature dependence of metal extraction into a magnetic product is presented in Table. 2

After screening, the slag had the following fractional composition, May. %:

-20 + 10 mm -10 + 0.4 mm-0.4 mm 2,542,555.0

The content of metal crowns in it is 4.5 May. %

Then, according to a known method, air separation was carried out in an upward air flow at a flow rate of x 10 m / s, the slag powder of the fraction less than 0.4 mm (dust removed) was removed from the slag, after which both products underwent magnetic (two-step) separation .

In the proposed method, after screening, it was additionally carried out for 10–15 min: the slag was treated in an air cooling flow, which was maintained at a speed of 4 m / s. Further processing of the slag was carried out, as in the known method.

The proposed method provides in comparison with the known increase of 8.5 abs. %, the extraction of metal in a magnetic product and a large (by 10.1 abs.%) metal concentration in a magnetic product. At the same time, the metal content in the non-magnetic product is reduced by 1.5 abs. %

Claims (1)

Invention Formula A method for processing low-carbon ferrochrome slags, including screening the raw material, air separation of the fraction material up to 20 mm in the upflow and magnetic separation of dust-free material, characterized in that to reduce the loss of metal with the non-magnetic product and improve the quality of the magnetic product, the fraction After screening, 20 mm is additionally treated for 10-15 minutes in an air cooling flow with the material moving in suspension to a temperature of about -60 ° C. Table f Processing time, min О 2 4 6 8 10 Content of the fraction -0.4 mm, May. % 55.0 57.5 63.0 77.2 86.9 93.1 Slag temperature, С-11-5 О 7 18 27 35 Extraction of metal into magnetic product,% 79.0 79.5 For initial (100% ) accepted the amount of metal nitric two-stage separation. Table 2 92.1 93.0 92.0 92.5 92.8 92.3 93.1 92.5 87.3 86.0 85.0 80.4 12 14 16 18 20 94.0 94.8 95 , 1 95.1 95.2 44 56 60 63 69 75 82 in pshak in front of the magician