SU971897A1 - Method for preparing slag-forming granules for steel smelting production - Google Patents

Description

C 54) THE METHOD OF OBTAINING CRUSHING PRODUCTS FOR STEEL MELTING

The invention relates to the agglomeration of powdered materials, in particular the production of exothermic slag-forming 1 granules used in steel casting, and can be used in the metallurgical and engineering industry.

A known method for producing exothermic slag-forming granules for steelmaking, in which the components of a mixture containing 30% silicate lump are crushed to a content of 65-80% of fractions less than 0.074 mm, moisten the obtained mixture with water at 5095 ° C and maintain it for 10-20 minutes one.

The disadvantages of this method are to obtain granules with low strength (about 4 kg / granule) with a high consumption of silicate block.

The closest in technical essence and the achieved result is a method of obtaining slag-forming granules for steelmaking using silicate lump as binder, including mixing, grinding the components of the mixture, moistening,: Granulation and subsequent drying

granules. The grinding of the components of the mixture is carried out together with a silicate block to a content in the mixture of 65-80% of a fraction less than 0.074 mm (the specific surface of such a mixture is about 1000). Drying is carried out in one stage by pumping a gas-heat carrier with a temperature of 150-350 ° C with a filtration rate of Of2.0 1.0 s for 20-30 min t2j.

However, the known method is characterized by an insufficiently high strength of the granules with a significant consumption of silicate lump.

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The purpose of the invention is to increase the strength of the granules.

The goal is achieved by the fact that in the method of producing slag-forming granules for steelmaking production using crushed silicate lump as a binder, including grinding the charge components, mixing them, moistening, granulating and drying the granules

lump grind to specific over the top. 2100-2700, after which it is added to the mixture, and the granules are dried in two stages: first 30; at 80-100 0 5-10 min, then at 200-300 0 10-15 min. When the granules are kept at a low temperature (80 ° C) for 5-10 minutes, the water present in the granules heats up, slowly and steams the solution of the silicate particle particles. In addition, evenly, the fine grain dispersed in the granules in the granules (specific surface area 2100-2700 CMVr) dissolves more intensively than the coarse lump, more water is formed in this process, which contributes to the strength of the granules. In the subsequent period of heat treatment at 200–300 ° C for 10–15 min, water is removed from liquid glass, which is accompanied by the bonding of charge particles among themselves, by strengthening of the granules. Thus, the step-drying of the granules and the fine grinding of silicate lumps contribute to obtaining durable granules. Experiments were carried out to obtain exothermic slag-forming granules under pilot-scale conditions, in which one of the parameters alternately changed in a wide range, all other conditions being equal. Components of the exothermic slag-forming mixture,%: aluminum 12 ,. manganese oxide concentrate 25, fluorspar 10, datolite 5, domain donkey 38, are mixed and crushed together to a particle size of 65% of a class less than 0.074 mm. The silicate g bu is crushed separately to a specific surface of 1000–3500 cm / g, after which it is added in the amount of 10% to the other components of the mixture. The resulting mixture is then moistened with water and granulated. Raw granules with a size of 8–15 mm are laid with a layer of 300 mm on the grate of an agglossa type firing plant and dried with a heating gas suction. Drying is carried out in two stages: first, at 50-130 ° C, 2-12 minutes, then at 150-350 ° C, 7-18 minutes. In tab. 1 shows the result of testing granules with silicate blocks of various size. The test results indicate the feasibility of using a silicate lump with a gage surface of 2100-2700 cMVr. A further increase in the grinding fineness of the lump, which is associated with the high energy consumption, is inexpedient, since the strength achieved satisfies the requirements of the steelmaking industry. Table 2 shows the dependence of the strength of the granules on the temperature of the drying, at the first stage. in tab. 3 shows the dependence of granule strength on the duration. drying in the first stage. From tab. 2 and 3, where the results of determining the optimal mode in the first stage of drying ensuring the production of granules with maximum strength properties are shown, it is clear that with further increase in temperature (over) and drying time (more than 10 minutes) in the first stage of drying there is no increase in the strength of the granules. This is because as the drying temperature rises, water evaporates more intensively and the process of forming liquid glass does not end. It is impractical to increase the exposure time, since the silicate lump has time to dissolve in 10 minutes. In tab. 4 and 5 show the dependence of the strength of the granules, respectively, on the temperature and duration of drying in the second stage. From tab. 4 and 5, it can be seen that with a further increase in the temperature and duration of drying, the strength of the granules decreases. At a drying temperature above 250 ° C, the water from the granules is removed so quickly that the duration of the contact of the hot water and the steam formed with the silicate block is not sufficient to completely dissolve it. The increase in drying time is also impractical, since the pellets have time to dry over the entire height of the layer for 15 minutes in the second stage of drying. The results of experiments to determine the dependence of the strength of the granules on the amount of silicate lump added are given in Table. 6. From the table. B it can be seen that the strength of the granules with 6% silicate lump, obtained by the proposed method, is close to the strength of granules with 10-15% silicate lump, obtained in a known manner. The method is optimally tested under semi-industrial conditions. The components of the slag-forming mixture are mixed and crushed together to a particle size of 65% of a class less than 0.074 mm. The silicate lump is crushed separately to a specific surface of 2400 and in an amount of 10% is added to the steel. nym components of the charge. The mixture is moistened and granulated on a plate granulator with a diameter of 1 m. The obtained granules are dried on a semi-industrial roasting plant of the aglochash type with a diameter of 300 mm. The height of the layer of granules 300 mm. Drying is carried out in two stages through the pumping down of the heat transfer fluid: first at 100 ° C for 7 minutes, then at 250 ° C for 12 minutes. For comparison, parallel experiments are carried out in a known manner. The results of the experiments are given in table. 7

According to the prototype method, the silicate lump consumption is 10-15%, while the compressive strength of the granules is 20-30 kg / granule.

The proposed method for producing slag-forming granules for steelmaking provides an improvement in the dosage of a silicate block and an increase in the strength of the dried granules in comparison with the known

which makes it possible to transport them over long distances. The use of stepwise heat treatment of granules and a fine silicate lump allows, in comparison with

5 in a known way to increase the strength of the granules 2.5-3 times or reduce the consumption of silicate lumps with a constant indicator of the strength of the granules (as in the known method 21-22 kg / granule)

10 to 4-9%.

Table 1

Table

Table 4

Claims (2)

Claims. . A method for producing slag-forming granules for steel-making using grinded silicate lumps as a binder, including crushing the components of the charge, mixing them, wetting, granulating and subsequent drying the granules, characterized in that, in order to increase the strength of the granules, the silicate lump grinds to a specific surface 2100Table 7 2700 cMVr, after which it is added to the mixture of charge components, and the granules are dried in two stages: first with SO-lOOc 520 for 10 minutes and then at 200-300 seconds for 10-15 minutes. Sources of information taken into account in the examination 25 1- USSR Author's Certificate ff 675081, KJi. From 22 to 1/00, 1976. 2. USSR author's certificate in application number 2814749 / 22-02,28.03.80.