SU840165A1 - Method of preparating charge for sintering - Google Patents

Description

The invention relates to the preparation of ore raw materials for smelting for ferrous and nonferrous metallurgy and can be used in the agglomeration of finely divided concentrates. There is a method of preparing the mixture for sintering, which includes pelletizing of finely ground ore materials with lime, drying the obtained granules with air or another gaseous agent and then mixing the granules with the rest of the charge components. To improve the gas permeability of the sintered layer and increase the productivity of the sintering plant, the granules are dried to a residual moisture content of 5-6% at room temperature (naturally)} fl. However, the known method of preparing the mixture for sintering does not allow to achieve the maximum possible aggregate capacity at a given quality. product, because it does not take into account the relationship between the drying speed of the granules, their residual moisture and strength in the dried state. The essence and the achieved result is the method of preparation of the sintering mixture for sintering, including its granulation, subsequent drying of the granules with sifting of granules less than 0.5 mm in the flowing layer and subsequent mixing of all components of the batch.In order to intensify the sintering process, the granules are dried to the residual moisture is not more than 2% at 300-600 C for 3-7 minutes, and the velocity of the heat-transfer gas is maintained within 18-26 m / s 2. The disadvantage of this method is that the moisture content of the granules (not more than 2%) corresponds totheir minimum strength. This is due to the fact that the strength of the granules during drying varies, successively passing through the maximum and minimum. The maximum strength of the granules corresponds to a moisture content of 3-4%, 3 to 8 minimum to direct drying, and in the moisture range of 3-2% a sharp drop in the strength of the granules to values close to the minimum is observed. As a result, the granules, dried by a known method, become unsuitable for transportation to mixing devices or sintering carts. In addition, sintering of the mixture containing dried (up to 1-2% moisture) granules should be carried out at a moisture content of 4-7%, i.e. the rest of the components. The mixture must be re-moistened for; preservation of average humidity, and this significantly aggravates the mixing of the granules with the rest of the components or causes the granules to reapply the granules with water (if it is partially supplied during mixing, which also negatively affects their strength, gas permeability of the layer and the capacity of the sinter plant. If, on the other hand, sinter only (with not more than 2% moisture, this will entail the thickness of the upper zone, an increase in the hydraulic resistance of the layer and the deterioration of heat recovery, i.e. In addition to the extremely unsuccessful choice of the residual moisture content of the granules, the known method did not take into account the possibilities of intensifying the drying process itself or the effect of its temperature parameters on the strength of the granules. The purpose of the invention is to increase the strength of the granules during their transportation and sintering and productivity of sintering machines. This goal is achieved by drying the granules to a residual moisture content of 3-4% at a heating rate of 50-600 deg / min. At the parameter In the proposed method, the heating rate of the granules during drying can reach 600 deg / min without deterioration of their strength. - Reducing the ash heating rate to 50 K / min intensifies the sintering process by improving the gas permeability of the layer, which provides an additional increase in the strength of the granules. 54 The process of drying the granules is characterized by several stages. In the first stage, when the capillary moisture evaporates, as it is removed, the adhesion strength of the particles increases, reaching a maximum value when the moisture content is 3-4%, close to the maximum molecular moisture capacity. Due to the high porosity of pelletized materials, the removal of capillary moisture occurs unhindered at heating rates of up to 600 deg / min. Subsequent drying removes molecular moisture, which leads to a dramatic softening of the granules. The method was tested in laboratory conditions on briquettes with a diameter of 7.1 and 4.8 mm, height 7.7 and 5.2 mm, respectively, prepared from Kachkanar titanium-magnetite concentrate. Their density is 3.22 g / cm-8% moisture, initial strength is 6 10 Pa and 4.2 10 Pa, respectively. The drying of briquettes is carried out in a furnace. The adjustable heating rate is at an air (gas) filtration rate of 0.2 m / s. EXAMPLE 1. The original briquettes are dried, with a heating rate of 200 degrees / min. Drying is carried out until complete drying and to a residual moisture content of 1-7%. In tab. 1-4 shows the effect of residual moisture on briquettes on their strength. PRI mme R 2. Initial briquettes are dried at a heating rate of 50 deg / min. The results of the experiments are given in table. 2. Example 3. Initial briquettes are dried at a heating rate of 600 deg / min. The results of the experiments are given in table. 3.: PRI me R 4. Source briquettes are dried at a speed of 700 degrees / min. At this heating rate, a rupture of the emulsion briquettes is observed, with which the heating rate is limited to 600 deg / min. Example 5. The original briquettes are dried natural) in air. The results of the experiments are given in Table 4. With natural drying in air at room temperature, the maximum strength of briquettes as compared with Examples 1-3 increases slightly, but the drying time increases dramatically (from 0.3-2.0 minutes to 3-4 hours), which makes it inappropriate to use the method. A similar character of the dependence of the strength of granules (briquettes from residual moisture (at the considered heating rates) was also obtained by increasing their initial density and equivalent diameter, respectively, to 2.8 g / cm 3, -0 mm. Cutting / sintering sintering mixture prepared according to the proposed and the known methods are given in Table 5. As can be seen from the examples given, the maximum strength of the granules during the drying process is achieved with a residual moisture content of 3–4%. With subsequent drying (as suggested in the known b; the strength of briquettes, other things being equal, depends on their size, but does not depend on the heating rate in the interval 50600 degrees / min. The data obtained show that the proposed method of preparing the mixture for sintering allows ing to tenify the drying process, increase the strength of the granules of the charge, determines their low crushability during transportation and sintering, as a result of which the productivity of the sintering plant increases by 15-17% while improving the ETS agglomerate at the exit of class mm 5 + 6.3% Sabsu. . Table 1

in the numerator - the strength of briquettes with a diameter of 7.1 mm, in the denominator - 4.8 mm.

t

Maximum residual moisture. The strength of the briquettes, 6.0 6.6 7.0 7.6 iii Pa. 5.5 6.4 6.9 7.5

Table M. lii ill lil 7,5 2,6 .2,1 2,1

The moisture content of the dried granules,%

The strength of the dried granules, Pa-Yu

The moisture content of the mixture (after mixing the granules with the other components),%

Equivalent diameter of charge granules, mm.

Equivalent diameter of the charge granules after 14 times dropping from a height of 2 m, mm

Specific productivity. Installations, t / m - hour 1,15

The strength of the agglomerate nd GOST 15137-77,

Table 5

3.0

2.0

1.25

0.5

6.0

6.0

4.1

4.1

1.2

2.9

1.32

Claims (1)

Claim A method of preparing a charge for sintering, including pelletizing finely ground ore materials, drying the obtained granules with a heat carrier gas, then mixing them with other components of the charge, characterized in that, in order to increase the strength of the granules during their transportation and sintering · ¹ 40 sintering machines and productivity, granules are dried to a residual moisture content of 3-4% at a heating rate of 50-600 deg / min.