SU1713937A1 - Method of making steel in converter using phosphorus-rich hot iron - Google Patents

Abstract

The invention relates to ferrous metallurgy, more specifically to methods for smelting steel from phosphorous iron in a converter. The purpose of the invention is to increase the dephosphorizing ability of the slag melt while simultaneously improving the quality of the phosphorous slag due to p-oxide. The method of smelting includes the filling of scrap, pouring iron with a phosphorus content of 0.5-1.4%. input of slag-forming agents, purging with gaseous oxidizing agent in two periods with intermediate downloading of phosphorous slag used in agriculture, supply of powdered lime in a stream of oxygen. Lime is served in a mixture with nepheline and apatite concentrate 1-4 minutes before the end of the first period of purging with a ratio of lime, nepheline concentrate and apatite concentrate 1:

Description

The invention relates to ferrous metallurgy, and more specifically to methods for smelting steel from special cast irons, such as phosphorous.

The purpose of the invention is to increase the crushing capacity of the slag melt while simultaneously improving the quality of the slag due to potassium oxide.

The method is carried out as follows: SIZE .-,.:,:,,. -. ; . . ; .

Scrap is poured into the converter, cast iron with phosphorus retention of 0.5-1.4% is injected, lime is injected and blown with a sulfur-like oxidant, for example, oxygen, in two periods with intermediate loading of phosphorus slag with a stream of powdered lime. - breed, while 1-4 minutes before the end

In the first purge period, nepheline and apatite concentrates were additionally added with lime at a ratio of lime, nepheline and apatite concentrate 1: (0.1-0.4): (0.6-4.0) to obtain CaO / (SiO2 + A1203 + P2O5) in phosphorous slag within 1,, 5,

Nepheline concentrate is a powdered material containing not less than 28.5% alumina (A1203). contains potassium oxides and is a raw material for the production of aluminum, soda, potash, etc.

Apatite concentrate is a powdery material with a P205 content of at least 39.4%, (Fe203 + A12Oz) - no more than 3%, the residue on the sieve with a grid of Ns 016K-not more than 11.5%.

Entering nepheline concentrate ensures the presence of phosphorous

. of potassium oxide slag, which leads to the formation of complex phosphorous fertilizer, and the introduction of apatite concentrate allows the introduction of active CaO and an increase in the phosphorus pentoxide content in phosphorous slag.

Lime must be mixed with nepheline and apatite concentrate 1-4 minutes before the end of the first purge period. When entering the mixture in less than 1 minute, homogenization was not achieved; When the mixture is introduced more than 4 minutes before the end of the first period, a large amount of potassium is consumed, which reduces the value of phosphorous slag.

 Lime must be injected at a ratio with nepheline and apatite concentrate 1: (0.1-0.4) :( 0.6-4.0). When a nepheline concentrate is introduced in a ratio of less than 0.1, complex phosphorous slag is not obtained due to a drawback: potassium is present in it, and when a nephane / clay concentrate is introduced more than 0.4, the deforming capacity of the slag melt deteriorates.

When you enter apatite concentrate in

 a ratio of less than 0.6, a slag with a high dephosphorizing capacity is not obtained, and when entering apatite concentrate more than 4.0

the phosphorus content in the metal due to an excessive increase in phosphorus pentoxide in the slag. The best indicators of slag dephosphorizing capacity and quality are achieved when the CaO / (SiO2 + A1203 + P205) ratio in the slag is in the range of 1.3-1.5. If the ratio of CaO / (Si02 + Al203 - P205) is not obtained in the phosphorus slag, the slag composition is adjusted within the indicated limits by entering lime, nepheline or apatite concentrate (within the proposed ratio) to obtain the ratio in the slag

; CaO / (Si02-t-Al20 + P205) in the range of 1.3-1.5. Testing of the proposed method for smelting steel was carried out in 300-ton converters. A nepheline concentrate was used with a content of 32.3% AlaOa, 22.8% (Na20 + K20), 44.6% 5102 O, 4% CaO. the rest is impurity and apatite concentrate with a content of 53% CaO, and 39% P205. the rest is impurity. The mixture is produced by displacing powdered lime, nepheline and apatite concentrates in the storage bin of the converter shop. Feed mixture

carried out through a five-tuber tuyere in a stream of oxygen with a flow rate of 2500 kg / min.

P ROME er. 5 tons of dolomite, 5 tons of lumpy lime and 90 tons of scrap are deposited on the final slag of the previous melt in the 300-tonne converter. Then 250 tons of pig iron with a content of 1.2% phosphorus, 0.8% manganese, 0.8% silicon, and 0.035% sulfur at 1340 ° C are poured.

On the 2nd and 4th minutes of the blowdown, 4 tons of lime are sown, and on the 12th minute (3 minutes before the end of the first period) a mixture of lime, nepheline and apatite concentrates is introduced for 2 minutes at a ratio of 1: 0.3 : 2.0 with an intensity of 2500 kg / min.

At the end of the first purge period, when the metal contains 0.6% carbon and 0.04% phosphorus, intermediate phosphorus slag is downloaded with a content of 44.2% CaO, 16.4% P205, 14.7% SlOa, 2.2% A120z. 0.0 & K20, 5.7% MnO, 6.1% MdO and 11.7% (PeO + Pe203) with a CaO ratio {{5102 + А120з + Р205) 1.3. After slag loading, a second purge period begins, in which 12 tons of lime are deposited. Steel is obtained, after deoxidation in the ladle, 1.8 tons of ferromanganese with a content of 0.07% carbon. 0.42% manganese, 0.008% phosphorus

and 0.013% sulfur.

To test the effectiveness of the method, experimental melting was carried out according to the proposed method and beyond the optimal limits, as well as by a known method.

Technological indicators of the bottoms carried out on the proposed and known methods are given in the table. Evaluation of the dephosphorus capacity of the slag melt is carried out by changing the phosphation ratio of the phosphorus between the metal and the slag, and the quality of the phosphorous slag is estimated by the content of phosphorus pentoxide and potassium oxide,

The data of the experimental heats show that the best results on the dephosphorizing ability of the slag rasplavu while simultaneously improving the quality of the phosphorous sclac are achieved with the delivery of lime, nepheline and apatite concentrates at a ratio of 1: (0.1-0.4) :( 0.6-4.0 ) 1-4 minutes before the end of the first purge period before the CaO / (Si02-i-Al203 - ' Fe205) ratio in the phosphorus slag is within 1.31, 5. In this case, as compared to the known method, the slag defining capacity increases by 3.4-2.9 times, while simultaneously increasing the K2O content in the slag by 0.02-0.07%.

Claims (1)

Invention Formula The method of steelmaking from phosphoric iron in the converter, including the filling of scrap, pouring iron with a phosphorus content of .4%. input of slag-forming agents, purging with gaseous oxidizing agent in two periods with intermediate downloading of phosphorous slag, supply of powdered lime in a stream of oxygen, o tl and c oo and so that, in order to increase the dephosphorizing ability of the slag melt while simultaneously improving the quality of the slag due to potassium oxide, 1-4 minutes before the end of the first purge period, nepheline and apatite concentrates are additionally added with lime at a 1: (0.1-0, nepheline and apatite lime ratio) 4): (0.6-4.0) to obtain the ratio CaO / (Si02 + Al2Q3-i-P205) in the phosphorous slag within 1.3, 1.5. :. -:. . . . :. . Porsametbrazka come to know.