SU1617002A1 - Method of melting steel in converter - Google Patents

Abstract

The invention relates to the field of ferrous metallurgy, more specifically to methods for smelting steel in a converter. The purpose of the invention is to improve slag formation and increase steel output. The smelting method includes purging with a change in the intensity of oxygen consumption, the supply of lime and / or dolomite of various fractions. At the time of the supply of lime and / or dolomite fraction 21-80 mm purge lead with an intensity of 3.1 m ³ / t ^. min, and at the time of filing lime and / or dolomite fraction of 5-20 mm purge lead with an intensity of 0.4-0.5 intensity of oxygen consumption when applying lime and / or dolomite fraction 21-80 mm, and after 0.5-1 ,5 minutes. After the supply of lime and / or dolomite fraction 5-20 mm, the oxygen consumption increases to 2.6 m ³ / min ^. The proposed purge mode allows, on average, a 2-fold increase in the distribution coefficient of phosphorus and an increase in the yield of steel by 1.4%. 1 tab.

Description

The invention relates to ferrous metallurgy, specifically to the methods of the steel production in steel in oxygen converters of various irons of cast iron.

The purpose of the invention is to improve slag formation and increase steel output.

At the time of the supply of lime and / or dolomite fraction 21 - 80 mm purge 11 must be conducted with an intensity of 3, 1 m / min-, t.

When purging a bath with such intensity, lime and / or dolomite of the 21–80 mm fraction is maximally heated due to the accumulation of heat from the exhaust gases, which makes it possible to improve its dissolution in the slag melt and slag formation, as well as to increase the yield of steel. When blowing metal with an intensity of less than 3.1 m / min, t, lime and / or dolomite is not heated efficiently and its absorption by slag is inhibited. When lime and / or dolomite is supplied with a fraction less than 21 mm, the amount of lime and / or dolomite carried with exhaust gases increases dramatically, and when lime and / or dolomite is supplied, more than 80 mm fraction dissolves.

At the time of supplying lime and / or dolomite of a fraction of 5 to 20 mm, purging must be conducted with an intensity of 0.4–0.5 of the intensity of the oxygen consumption during the supply of lime and / or to CF

Bhi

Lomita fractions 21 - 80 mm. With a pro dude with an intensity of less than 0, 4 - 1 intensity of oxygen supply with lime and / or dolomite fraction 21. - 80 mm, the converter capacity decreases sharply by increasing the duration of the blow.

Without a significant improvement in slag formation, and when blowing with an intensity of more than 0.5, dramatically increase the exhaust and / or dolomite with waste - 1 | 1 with these gases and increase its loss, worsens the conditions of slag formation.

ten

Testing and testing the effect of the proposed method was carried out in 320-tonne constructors in the case of phosphor-iron. Melting was carried out with separate feed and lead and / or dolomite of fractions 5 and 21 - 80. mm in the converter. The melting was performed using the final slag of the previous melting two periods with an intermediate slag jump. Oxygen consumption in swimming trunks 850. The conditions of the slag development were evaluated by the coefficient

1 --- g - - jiJa.ouDann “identified by COEFITION

| and. When adding lime and / or dolomite, 5 phosphorus distribution (Lp). between the range of less than 5 mm ne kp vRpnMUMna- v "am ,,," ...,

fractions less than 5 mm increase dramatically; tc the amount of lime carried, c1 when lime is introduced and / or dolomite. Lime fractions more than 20 mm and / or dolomite do not get warm enough, which leads to deterioration of slagging conditions.

I After 0.5 - 1.5 minutes after the supply of Lime and / or dolomite fraction 5 - 40 mm, the oxygen consumption must be increased to 2.6 m / min. This is due to the fact that in the case of Zije purge .2.6. T oxygen consumption: dramatically increases the duration of the purge without significantly improving the dissolution of lime and / or dolomite and slag formation, and in case of an increase in the nominal oxygen consumption Bbmie the slag conditions deteriorate.

With an increase in the consumption of oxygen to the nominal in less than 0.5 minutes after the supply of a fraction of 5 to 20 mm, there is a loss of lime and / or dolomite with: exhaust gases due to removal, and in the case of an increase in oxygen consumption to the nominal more than for 1.5 min., the duration of the purge is increased without significant improvement in the formation and increase in the yield of steel.

Thus, in steel smelting In a converter, at the time of supplying lime and / or dolomite of a 21–80 mm fraction, it is necessary to conduct a blower with an intensity of 3.1 m / min-t, and at the time of supplying lime and / or dolomite of a fraction of 5 - 20 mm with an intensity of 0.4–0.5, the intensity of oxygen consumption when supplying lime and / or dolomite of a fraction of 21–80 mm, and 0.5–1.5 minutes after the supply of lime and / or dolomite of a fraction of 5–20 mm

25

thirty

35

40

45

50

55

metal and slag at the end of the second purge period and at the exit. It was taken into account that the higher the phospho (Lp) distribution coefficient, the higher the defocusing capacity of the slag melt is used and, therefore, the better the conditions of slag formation. The presence of well-formed molten slag makes it possible to increase the output of steel by reducing the loss of metals with and with slags both in iron oxide and in the form of cores.

An example. After the metal is drained from the converter, 4 tons of dolomite and 5 tons of lead are brought to the inactive state to transfer the remaining slag into the inactive state, 110 tons of scrap are poured, and 250 tons of pig iron at a temperature of 134 with a content of 0.80% manganese, 0.8 silicon, 1.20% phosphorus and 0.035%. After pouring, the cast iron converter is placed in a vertical position, the lance is lowered and rinsed with an oxygen flow rate of 1000 m / min (maximum intensity for this converter) for 15 minutes. During the first period of blowing through, portions of 2-4 tons of lime of 14 tons of fraction 21-80 mm are consumed. At the end of the first period of blowing, metal contains 0.58% carbon, 0.038% phosphorus at a temperature. After downloading the intermediate slag, the lead is blown with an oxygen consumption of 500 (0.5 of the intensity of the blowdown when the lime is supplied to the fraction 21-80 mm), 12 tons of the fraction 5-20 mm to the 4th minute are deposited 1 minute after the end of the lime fraction 5 - 20 mm oxygen consumption increases from 600 to

. - „., ...„ „v / Г1М pciu- oxygen is increased from 600 to

the course of oxygen is increased to 2,. t, 850 m / min (nominal flow) and

0

Testing and testing the effectiveness of the proposed method was carried out in 320-tonne constructors at the limit of phosphorous-cast iron. Melting was carried out with a separate feed of lime and / or dolomite of fractions 5, 20 and 21 - 80. mm in the converter. Experimental melting was performed using the final slag of the previous melting in two periods with intermediate slag downloading. Oxygen consumption in swimming trunks 850. The conditions of slag formation were evaluated by the coefficient

jiJa.ouDann “identified by COEFFICIENCY

5 phosphorus distribution (Lp). between v "am ,,," ...,

, 5 phosphorus distribution (Lp). between v "am ,,," ...,

0

five

0

five

0

five

0

five

metal and slag at the end of the second purge period and the steel output. It was taken into account that the higher the phosphorus distribution coefficient (Lp) is, the higher the deforforming capacity of the slag melt is used and, therefore, the better the conditions for slag formation. The presence of well-formed liquid slag allows to increase the yield of steel by reducing the loss of metal with and with slags both in the form of oxides and in the form of cores.

An example. After the metal is drained from the converter, 4 tons of dolomite and 5 tons of lime are put in the inactive state to transfer the remaining slag, 110 tons of scrap are poured, 250 tons of pig iron are poured at a temperature of 1340 seconds with a content of 0.80% manganese, 0.80% silicon, 1.20% phosphorus and 0.035% sulfur. After casting, the cast iron converter is placed in a vertical position, the lance is lowered and rinsed with an oxygen consumption rate of 1000 m / min (maximum intensity for this converter) for 15 minutes. During the first purge period, 14-4 tons of lime are added to portions of 2-4 tons each. At the end of the first purge period, 0.58% of carbon and 0.038% of phosphorus are present at the temperature in the metal. After downloading the intermediate slag, purging is carried out with oxygen consumption 500 (0.5 of the intensity of the purge when lime is supplied to the fraction 21-80 mm), 12 tons of lime 5 to 20 mm up to the 4th minute are placed. 1 min after the end of the additive. lime fraction 5 - 20 mm oxygen consumption increases from 600 to

oxygen increase from 600 to

850 m / min (nominal flow rate) and

blown to a carbon content of about 05% in the metal and temperature TbOO C. The chemical composition of the metal at the end of the second purge period,%: carbon 0.05; manganese 0.06; phosphorus 0,0 - 0,8; sulfur 0.014. The final slag contains,% Fe024,8; 7, 73; CaO 50.14; 5gO 7.66. The release and deoxidation of the steel is carried out in a ladle using the 1.7 tonnes of FeMn additive used in the workshop. Get steel containing,%: carbon 0,06; manganese 0.36; K15 dark 0,006; phosphorus 0,008; sulfur 0.014, corresponding to steel HVKP.

Spreading of materials and smelting: 240 tons of pig iron, 110 tons of breaking, 31 tons of lime, 4 tons of dolomite, 1.7 tons of FeMn.

The main indicators of heats, carried out by the proposed method with the output beyond the optimal values, as well as by a known method are shown in the table.

The results of experimental heats and studies show that the best conditions for slagging and increasing steel output are achieved when at the time of lime feed and / or dolomite fraction 21 - 80 mm purge is carried out with the maximum intensity for the converter used, and at the time of lime feed and / or dolomite fraction 5 - 20 mm purge lead with the intensity of oxygen consumption 0.4 - 0.5 intensity when applying lime and / or dolomite

fractions 21-80 mm, and 0.5–1.5 minutes after lime lime donations of a fraction 5-20 mm, the oxygen consumption should be increased to nominal. In this case, the distribution coefficient of phosphorus in the swimming trunks, carried out by the proposed method, in comparison with the melts carried out by a known method, is increased by 87% (from 382 to 716), and the steel output increases. 1.4X

Claims (1)

Invention Formula The method of steelmaking in the converter, including blowing with a change in the intensity of oxygen supply, input of lime and / or dolomite fractions different In order to improve slag formation and increase steel output, lime and / or dolomite feed is made separately in fractions of 21–80 mm and 5–20 mm, while at the time of lime and / or dolomite feed, fractions 21–80 mm It has an intensity of 3.1 m., and at the time of the supply of lime and / or dolomite fractions 5 to 20 mm purge lead with an intensity of 0.4 - 0.5 intensity of oxygen consumption when supplying lime and / or dolomite fraction 21 - 80 mm, and after 0.5 - 1.5 min supply of lime and / or dolomite fraction 5 - 20 mm oxygen consumption increase to 2.6 m / min.