SU783344A2 - Method of slag production in steel smelting - Google Patents

Description

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 The invention relates to the field of ferrous metallurgy, in particular to the production of steel in hearth steelmaking units.

There is a known method of pointing slag 5 in steel smelting according to the main ed. St. 501078, which includes feeding the slag to the surface during the period of smelting and finishing as a diluting agent a staurolite concentrate in the amount of 2-8 kg / t of steel. With this method, slag formation is accelerated due to the high dilution capacity of staurolite .15

This method has the disadvantage that the staurolite, having a fine fraction (0.1-0.5 mm) and a relatively low specific weight (2100 kg / m), with 20 additives on thick slags does not sink into the bath, but remains on the surface of the slag within 10-15 minutes This phenomenon inhibits the effect of staurolite on the donkey as an effective 25 thinner and reduces the degree of desulfurization of the molten metal.

The aim of the invention is the acceleration of slagging and blasting;

the degree of desulfurization of the metal. thirty

This goal is achieved by introducing the stavrolite concentrate in a mixture with a solid oxidizing agent in a ratio of 1: (0.2-1.0).

With this method, the addition of a staurolite concentrate (in a mixture, for example, with dross), the processes of slag formation, carbon oxidation and heating of the metal reinforce each other. On the one hand, the improvement of the conditions of interaction of staurolite with slag as a thinner is related the mixture in the slag, and active sparging in the area of the additive due to the interaction of scale with carbon in the metal. On the other hand, the acceleration of slag homogenization in the bath accelerates not only desulfurization. but also the processes of carbon oxidation and metal heating. This makes it possible to shorten the duration of the smelting period by speeding up the frequency of operations for decarburization, slagging and desulfurization of the metal used in the separate input of the oxidizing agent and the staurolite concentrate.

The proposed ratio of stavro.litovogo kbntsentrata and oxidizer

1: (0.2–1.0) is optimal because it provides maximum performance from any stavion. Different ratios are used depending on the excess carbon content in the metal. The optimum excess of the carbon content in the metal at the end of the melt over the average precipitate in the finished steel is usually limited to the bottom in "px-; him beyond. Thus, for 250-tonne open-hearth furnaces with a moderate effect of the purging of the bath with oxygen, the recommended carbon content for melting should be greater than the average e of the finished steel by 0.81.2%. At the same time, the intensive conduct of the peribda finishing of the dusmat |

polishing with solid sulphides. The ratio of stabroli-loci8a

one; (6,2-1,0) corresponds VSEZMYZKSHLU

and permissible soda limits) Z a: no carbon in the metal after melting.

An example of the method.

To compare the technological indicators of various methods of using slag thinners at the Makeevka Metallurgical Plant, pilot melts were conducted at the 250-ton open-hearth. Alloyed steel grades with a sulfur content in the finished steel of no more than 0.030%. Ras: a limestone run into the filling was located § preliminaries 1 - 36 tons. PlamensNavadaShsB n & fpiiM options: separate supply of bauxite and scale, staurolite and onaline, feed mixture of staurolite and scale in various ratios.

Due to the increased consumption of limestone in the filling at all melts and at the end of the melting, significant slag thickening is observed due to the large number of different fractions of undigested lime. Separate addition of bauxite and scale led to the fact that long-term bauxite cakes were on the surface of the slag, and scale additives caused only local temporary activation of Banna. Separate addition of staurolite and okaygyga is spontaneously accelerated by 1yr & 1 3; ё1 b of general activation of the bath and the dilution of slag. However, during the period of 15–20 m, a thick section with lime was observed on the surface of the bath, on the surface of which was undigested staurolite.

Additives of staurrlitic concentrate in a mixture with scale were accompanied by moderate activation of the bath, first in the area of the additive, and then over the entire surface. After 5-10 minutes u4zva: yid lidnaiKOM not only the mixture was planted, but also the pieces were not divided by the time the lime was added.

When planting a staurolite concentrate with dross, the processes of formation and oxidation of carbon mutually accelerate each other, and the favorable conditions are created for the assimilation of additional portions of lime in case of need of their additive.

Yao Rezul | 1T 1t ogshtnye melts with the use of stavrolite concentrate mixed with dross, the speed of monkeys glerenia increased by 0.08% / h compared to conventional technology and by 0.0b% / h - using staurolite concentrate And 3Ally and speed de youLuflation of the metal increased ria 2,1.10-% / hour.

The use of TaJKprp in this production process. Slag hovering method allows to conduct an ayakbreeding process, increase the desulfurization of metal, which together contributes to an increase in the productivity of the steelmaking unit and improves the quality of the smelted metal, l

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Claims (1)

-, .h, .- v. . ./,. Invention Formula Slag hovering method in steel smelting according to aut., St. No. 501078, characterized in that, in order to accelerate slag formation and increase the degree of desulfurization of the metal, the STT concentrate is mixed with solid oxidizer B in the ratio 1: (O, 2-1.0), respectively. .,., ..: .. ..-...-; ,