SU1013489A1 - Method for smelting steel in converter - Google Patents

Description

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The invention relates to metallurgy and can be used in the smelting of steel from low-manganese iron in oxygen converters with upper and lower blast.

A method of producing steel from low-manganese iron is known, which involves blowing metal with oxygen, directing slag by supplying lime. In this method, the basicity of slag is 5.0-6.0.

The disadvantages of this method are the high basicity of the slag and, as a result, the low rate of the refining reactions and the whole process as a whole.

The closest to the invention to the technical essence and the achieved result is a method of steel smelting in a converter, including blowing metal with oxygen from above {and below, downloading oxidative slag, directing new slag by feeding low-phosphorous manganese-containing slag from ferroalloy production and lime, feeding silicon-containing materials and recovering it. basicity 2-3.5, mixing of metal and slag C - 1

The disadvantage of this method is the high basicity of the slag at the beginning of the reduction process, which leads to an increased consumption of silicon-containing materials, and with the use of a thinner, and the high cost of steel produced.

The aim of the invention is to reduce the cost of steel.

The goal is achieved in that according to the method of steelmaking in the converter, which includes blowing the metal with oxygen from above and below, downloading oxidative slag, directing new slag by supplying low-phosphorous manganese-containing slag of ferroalloy production and lime, supplying silicon-containing materials and lime to obtain basicity of 2-3.5 , mixing metal and slag, supplying silicon-containing materials and lime is carried out in portions every 2–3 minutes, and the portions are 1025 of the total consumption, after the supply the last one exposure portion is carried out for 2-3 minutes and stirring lead metal by blowing inert gas with the intensity of 1, X 0m7th min.

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The essence of the invention is as follows.

In the production of manganese fergus rosflavs, low-phosphorus manganese-containing slag of the following composition is formed, weight: MnO C-70. SiOn, CaO 0, MgO 0.2-3.0, FeO 0.2-0.8: 0.1-i “, o: P 0.010, 05. When smelting manganese-containing 10 steels in the converter leads to slag from low-phosphorous manganese-containing slag from ferroalloy production, and then the silicon-copper elements are reduced by burning materials, elements that have a lower affinity for oxygen than silicon should be recovered. At the same time, reactions of reduction of iron, phosphorus and manganese take place:

° 2FeO + Si Si02. + 2Fe

2P20j + 5Si 5Si02 + P 2MnO + Si SiOj, -f 2Mn Due to the fact that low-phosphorous slag is used, the recovery of a small amount of phosphorus does not significantly affect the properties of the steel. When manganese is reduced from Margon oxides, slag basicity must be at least

0 two, otherwise the silicon will go into the metal and not work. as a reducing agent, for example, with a basicity of 1.3, the amount of silicon in the metal can be up to 1.5. With basicity more

5 3.5 in the slag, the amount of unassimilated lime increases, the slag becomes heterogeneous and additional operations are necessary to dilute it — entering the slag

0 Sar2, Si02 or silicon and slag blowing.

In addition, in the reduction of elements from the slag, the product of the reduction is also silica, which significantly reduces the basicity of the slag. The size of portions of silicon-containing materials and lime in the amount of 10-25% of their total required amount is chosen from the calculation

 convenience of maintaining the required basicity and processability. Thus, the use of portions below 10 of their total amount is impractical because it leads to cooling of the bath and an increase in the duration of smelting, the use of over 251 is also impractical due to the fact that difficulties arise in supplying 3G large portions of materials and difficulties in maintaining the required basicity. The interval between the feeding of portions is selected for 2-3 minutes, since, if the interval is less than two minutes, the necessary slag may not be formed and the reduction reaction will not have time to complete. Exposure of more than 3 min is also impractical, since it only leads to elongation of melting and cooling of the bath. In order to improve the mixing of the reacting phases, in the reduction process they inject with an inert gas or nitrogen with an intensity of 1.5-2.0 per ton of steel. Purging intensity less than 1.5 per ton of steel does not provide sufficient mixing, and over 2 m / min per ton of steel is undesirable as the gas flow rate increases and the bath temperature drops much faster. PRIme R. The smelting of manganese-containing steel grade is carried out in a 60-kilogram converter with top and bottom blowing. At the bottom of the converter, 2.5 kg of lime is charged and 50 kg of cast iron are poured with the temperature of the following chemical composition: C 3.9 MnlO, 72, 8 S 0, P 0.020. The bath is purged with oxygen with an intensity of χ x X min (oxygen content 39.2%) through the upper lance with a nozzle with a diameter of 2 mm, located at a distance of 60 mm above the level of the quiescent metal. Blowing is stopped at the eighth minute. When the content of carbon in the metal is 0.03% and t. After downloading the maximum possible amount of slag (about 95%) under these conditions, 5 kg of low-phosphorous manganese-containing ferrous alloy slag from the following chemical composition D is loaded into the converter: SiOg 25 MpO 65; CaO 5-, 5: FeO 0,2: APgOs 2,2; M 2.3, P 0.01. Simultaneously with the supply of slag give. 2.5 kg of lime and rinse the bath with argon for 12 minutes through a bottom tuyere with a nozzle with a diameter of 2 mm and an intensity of 1.5 m / min per ton of steel. The basicity in this case is 2.3. Then, starting from the second minute of the purge, five pieces of 0.175 kg of 75% ferrosilicon and 0.6 kg of lime are given in the converter; the interval between feeding the portion is 2 minutes. Due to such lime feeds, the slag basicity is maintained at a level of 2.2-2.25. Two minutes after the last portion of the ferrosilicon and the lime are supplied, the metal is poured into the ladle. Before discharge, the metal temperature is 1 ° C. When metal is discharged under the stream, 1bOg of ferrovanadium gives a vanadium content of t5%), nitrated manganese with a nitrogen content of 5% in an amount of 258g and 50g of aluminum. The resulting metal is cast into molds for a weight of 20 kg. The ingots are forged onto cards41 with a thickness of mm and, after heat treatment, mechanical properties are determined on them. To compare the quality of steel obtained by the proposed technology and the known scheme, a comparative melting of steel in the same converter with the introduction of metallic manganese was carried out. The resulting metal was also installed on cards with a thickness of 20 mm. The chemical composition (Table 1) and mechanical properties (Table 2) of the steel after normalization and tempering were determined on experimental and comparative maps. Table 1 ,

Table 2

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The metal obtained according to the expected expected economic effect

The way to the method corresponds to the me-from the implementation of the proposed isobalt, obtained by the usual technique, reteni in the production of 100,000 tons

At the same time, while reducing the cost of steel ingots, the average cost was 1.21. rubles, 1.5 million rubles.

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Claims (1)

METHOD OF STEEL MELTING IN THE CONVERTER, which includes blowing metal with oxygen from above and below, loading oxidizing slag, introducing new slag by feeding mayofosforistro manganese-containing slag of ferroalloy production and lime, feeding silicon-containing materials and lime to * obtain basicity of '2 ~ 3.5 ash, mixing characterized in that, in order to reduce the cost of steel, the supply of silicon-containing materials. and lime is carried out portionwise every 2 ~ 3 min, and the portions are 10-25? of the total flow, after feeding the last portion, hold for 2-3 minutes, and stirring is carried out by purging the metal with a neutral gas with an intensity of 1.5 ^_ 2.0 ^h m ^ / tmin. § GO 00 CO>