SU1298256A1 - Method for steelmaking in oxygen converter - Google Patents

Abstract

This invention relates to the steel industry. The purpose of the invention is to increase the yield of liquid metal and reduce the consumption of cast iron, which is achieved by adding solid fuel and moving the tuyere in the vertical direction during purging. 40-50% of the total consumption of lime smelting load on the bottom of the conveyor. The first 10-15% of the time is purged from a distance of 65-75 given tuyere gauges from the level of the calm bath. The next 15–30% of the time from the start of the purge is from a distance of 35–40 given calibers. Solid fuel is applied to the next 30-60% of the time from the start of the purge, and purge during this period is carried out from a distance of 65-75 given calibers, and then purge is purged from a distance of 35-40 given calibers to the end of the melt. This method of steelmaking allows to increase the yield of liquid steel by 2.0-2.5% while reducing the consumption of liquid iron on average by 3-5%. 1 tab. from 9 00 ate

Description

The invention relates to black metal, in particular to steel production in oxygen converters.

The purpose of the invention is to increase the output of lshd metal and reduce the consumption of iron

Carrying out the initial period of smelting with the elevated position of the tuyere above the level of the calm bath allows you to quickly bring in the primary slag with a high content of iron oxides. At a low metal temperature during this period, the activity of iron oxides is quite sufficient5 to impregnate pieces of lime with iron acid II and prevent the formation of a refractory shell of two 1-shee tricalcium silicate. This means that during this period, conditions are created for the quick dissolution of lime in the clay melt. Therefore, part of the lime to successfully carry out the process of formation of lime must be introduced before the start of smelting to the bottom of the converter, while the optimum amount of lime is 40-50% of its total smelting expense. The amount of lime that is sown during this period does not exceed 50% of the shell; its quantity is j because its cooling effect leads to a cold start of melting 5 resulting in the ejection of metal and donkey from the converter S 40% of the total mass is added to lime on the bottom of the converter the amount of lime introduced during the blowing process is increased in this case, the degree of absorption of lime is reduced; the basicity of the final donkeys is reduced and the desulfurization of metal and metal dephosphorization is reduced. The position of the tuyere in the initial period; 65–75 calibers from the ypOBi-sh calm bath, however,

The position of the tuyere over the bath in the initial period of purging should not exceed 75 given calibers. At a higher position of the tuyere on the tub, the tub kinetic energy of the jet decreases, which leads to a slower discharge of the smelting, excessive coke of iron oxides and slag. subsequent lowering of the tuyere into the working position - to the dramatic development of decarburization and emissions, in addition to the risk of burning the converter lining under the influence of oxygen jets reflected by the scrap metal

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closer location of the burning spot to the lining,

When the tuyere is positioned above the bath in the initial period of blowdown of less than 65 calibers from the level of the quiescent bath, the accumulation of iron oxides in the slag decreases, as a result of which lime absorption is slowed down. In addition, the danger of damage to the tuyere tip of pieces of unmelted scrap metal increases. The termination period of the initial slag should be at least 10% of the purge time, otherwise the message will not have time to dissolve in the slag, and not more than 15%, since this will burn a lot of iron and reduce the yield of the liquid metal.

After 10-15% of the time spent blowing the lance down to the working position equal to 35 AO of the given calibres of the tuyere, and continue blowing up to 30% of the time, as after E. TOTAL time the bath decarburization reaction begins to develop.

The position of the tuyere over the bath during the working period is determined to deepen the jet stream into the bath; the distance of the tuyere from the level of the calm bath is 35–40 given tuyere gauges. The oscillations in the position of the tuyere above the level of the calm state of the bath depend in each particular case on the composition of the iron, its temperature and other technological parameters of smelting.

After 30% of the time the purge begins, the reaction of the freezing bath begins to develop. The carbon burn-out rate during the decarburization period is limited by the rate of reduction of the iron Cr from the slag, as a result of which the slag viscosity drastically increases5 s and the capacity of the converter.

In order that the oxidation reaction of carbon does not develop to the level of excessive reduction of iron oxides

Q in the slag, during this period is necessary

apply solid fuel and purge from a distance of 65-75 given calibers from the level of a calm bath, i.e. as in the initial period of the projection with the distance of 65–75 given calibers of the metal bath and the fuel with oxygen, combustion of the fuel and iron proceeds, which leads to heating of the bath. Form0

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Iron oxides react with carbon, as a result of which iron is reduced, and carbon monoxide that forms with carbon is burned in the bulk of the converter, which improves the heat side. Putting a tuyere during this period should not exceed 75 given calibers. At a higher position of the tuyere above the bath, excessive accumulation of iron oxides in the baton occurs, which reduces the yield of the liquid metal. When the tuyere is positioned above a bath of less than 65 calibers, from the level of a calm bath, incomplete afterburning of CO to CO in the volume of the converter occurs, which worsens the thermal side of the process.

The use of heat from the afterburning of CO to COj in the volume of the converter, in addition to the heat from the combustion of solid fuel, makes it possible to work with a lower consumption of liquid iron than by a known method. Work with a reduced consumption of molten iron helps to increase the yield of molten metal by reducing the waste of iron impurities.

In addition, such a regulated blowdown allows the rate of carbon oxidation to be maintained at a sufficiently high level, induce liquid-mobile ferrous slag, and reduce metal losses with emissions and effluents, which will further increase the yield of the liquid metal. As the decarburization rate decreases, when the carbon concentration in the metal is reduced to low values, the lance is lowered and the purge is continued from a distance of 35–40 of the above calibers to the end of the heat.

Example 1. In a 160-ton converter, an iron of composition is blown,%: C 4.2; Si 0.54; Mp 0.75; S 0.016; P 0.21. The consumption of pig iron, scrap and lime in the filling is respectively 104, 56, 4 tons (42% of the total consumption). The entire purge time is 20 minutes, the intensity is 400. Up to 3 minutes of purging (15% of the time) the position of the tuyere is set to 2.5 m (71 caliber given), then the lance is lowered to 37 calibers (1.3 m), for 7 min of blowing the tuyere it is raised to 2.5 m and the coking seat is set in the amount of 3 tons (2% by weight of the charge), for 13 minutes the lance is lowered to 1.3 m until the end of the purge. In the course of blowing sit down

g 10 15

20 25 30 h5 40

njiaFiUKOBbii i spar and lime, the consumption of which is respectively 0.3 and 6.65 tons. The temperature of the metal on the roll is 1615 ° C, the metal contains,%: C 0.18; Ml 0.14; P 0.010; Р 0.012, slag base 4 and Z FeO content 21.5%, liquid steel yield 91.6%, liquid iron consumption 65%, scrap consumption 35%.

Example 2. In a 160-ton converter, the composition cast iron is blown,%: C 4.2; RA 0.65; No. 0.74; P 0.22; S 0.019, The consumption of pig iron, scrap and lime in the filling, respectively, is 96, 64, 5.5 tons (50% of the total consumption). The whole purge time is 20.1 minutes, the intensity is 400. Two minutes (10% of the time) purge when the position of the tuyere is 2.6 m (75 calibers listed), then the tuyere is lowered to 40 calibers (1.4 m), for 7 minutes of purging the tuyere is raised to 2.6 m 5.6 tons (3.0% of the weight of the charge), for 13 min the lance is lowered to 1.4 m until the end of the purge. In the course of the blow down, fluorspar and lime are sown, the balance of which is 0.3 and 5.5 tons, respectively. The temperature of the metal on the roll is 1610 ° C, the metal contains,%: C, 0.10; Mp 0.17; P 0.010; G 0.010, slag basicity 3.9 and ZFeO content 22.1%, liquid steel yield 92.1%, liquid iron consumption 60%, scrap consumption 40%.

From the given examples of the method implementation it can be seen that the application of the proposed method (examples 2 and 3) makes it possible to reduce the consumption of pig iron to 60%. Additional examples of the method with various combinations of technological parameters are given in the table,

Claims (1)

45 claims A method of steel smelting in an oxygen converter, including metal scrap loading, smelting of liquid iron, solid fuel additive in an amount of 0.5-3.5% by weight of the charge metal, and oxygen blowing with lime feed, characterized in that, in order to increase the yield of liquid metal and reducing the consumption of iron, the lime feed is carried out in the filling to the bottom of the converter in the amount of 40-50% of its total melting powder, while blowing 50 55 In the first 10–15% of the time, talla are ejected from a distance of 65–75 given tuyere calibers from the level of a calm bath, for the next 15–30% of the time from the start of blowing, they are taken from a distance of 35–40 given calibers, and solid fuel is placed in 82566, the next 30-60% of the time from the beginning of the purge and purge during this period are carried out from an altitude of 65-75 given calibers, after which the purge is continued from a distance of 35-40 in the calibers given until the end of the melt.