SU1708864A1 - Method of steelmaking from phosphoric hot iron in basic oxygen furnace - Google Patents

Abstract

This invention relates to the steel industry. The purpose of the invention is to increase the yield and reduce the cost of steel. This is achieved by using high-ash low-sulfur steam coal with a content of 40 - 0 May. % ash containing 25-30 wt.% alumina, 3-5 wt.% oxides of alkaline-earth elements and 0.01-0.1 wt.% sulfur. Power coal is placed on the cast iron before the start of the purge and after wetting the intermediate slag at a cost ratio

Description

The invention relates to metallurgy, and more specifically to the production of steel from phosphorous iron in oxygen converters.

The purpose of the invention is to increase the yield and reduce the cost of steel.

The method is carried out as follows.

In the converter, slag of previous melting is left, dolomite and lime are sown, scrap is loaded and liquid iron is poured in and the bath is purged with oxygen for two periods with wetting of the intermediate slag, while high-voltage steam coal containing 40–50 wt.% Ash is sown in two portions - the first on the cast iron turn of the start of blowing, and the second after wetting the intermediate slag before resuming the blow, the expense ratio in the first and second positions is (2-1): 1 with a total consumption of 1 kg / ton of steel. Power coal ash contains 25-30 wt.% Aluminum oxide, 3-5 wt.% Oxides of alkaline-earth elements and 0.01-0.1 wt.% Sulfur. The essence of the invention consists in the use of a new low-sulfur diluting agent, the ash of which has so-called pl. 1100-1150 ° C and due to the high content of aluminum oxides and alkaline-earth elements, it contributes to the rapid dissolution of lime and the maintenance of liquid slag during the entire flushing. The addition of the reagent to the cast iron before the start of the blowing contributes to the rapid heating of the smelting, has a positive effect on its heat balance and, apart from the Torof, the use of high-ash energy coal makes a relatively small amount of sulfur, the removal of which does not require additional lime consumption. It should be noted that there is a decrease in the viscosity of the slag and the number of metal cores in it, which reduces metallope losses, and with wetted slag.

It has been established that with a total consumption of steam coal less than 5 kg / ton of steel, aluminum oxides and alkali-aemel elements are not sufficiently injected, which does not allow to obtain optimal indicators due to the slow dissolution of the monster and metal deposits (table, example 5). In this case, due to the low calorific value of high ash coal (3600-3900 kcal / kg), a noticeable decrease in the consumption of pig iron is not achieved, which leads to an increase in the cost of steel. At power consumption of more than 10 kg / t of steel, the blowing is unstable under the liquid slag, especially when the content of silicon is high; in the iron, as a result, slag emissions are observed, leading to a decrease in the amount of metal in the wetted slag, does not require additional lime additives That improves the heat balance of melting.

An example of the method.

The method was carried out in 300-ton KCIH-invertors when smelting steel 08 kp for steel production. In the converter, slags from the previous smelting are left, 4 tons of dolomite and 4 tons of lime are sown, 110-115 tons of scrap are loaded (bulk density is 0.9-io tons / m and 245-250 tons of pig iron with a content of 0.60, 65% MP, 1.25 - Т; ЗГа wt;% Р, 0.75-0.80 wt.,% Silicon and 0.032-0.035 wt.% Sulfur. The amount of high-ash coal in the converter is placed on the cast iron and before the beginning of the 2nd period 5-10 kg / ton, at a ratio of costs in the first and second portions (2-1): 1. Oxygen consumption averages 1000 im / min. In the first period 10-14 tons of lime are sown and at a content of 0.6- 0.8 wt.% C and the temperature of the metal 1540-1560 ° C. The intermediate slag is wetted.

In the second period, before the start of the purge, the rest of the high-ash coal is planted in the converter and the purge is deposited, during which 10-14 tons are placed in the converter; to lime. The purge is completed at 0.05-0.06 wt.% C, 0.05-0.06 wt.% Mn, 0.008-0.01 wt.% P and 0.007-0.01 wt.% Sulfur at 1615-1625 ° s The total duration of the purge 20-20.5 minutes In the process of deoxidation, 1.8 tons of ferromanganese and 15-45 kg of aluminum are placed in the ladle.

The results of the experiments are presented in the table.

Analysis of the above results shows that when using high-ash coal energy, slag and thermal conditions of smelting improve, as a result, the steel yield increases by an average of 1.2%, and the cost of steel decreases by 1.0rub / t.

Claims (1)

Invention Formula The method of smelting steel from phosphoric iron in an oxygen converter, which includes leaving and neutralizing slag, filling all the scrap before pouring iron, adding carbon-containing material in two portions: first to cast iron before starting to blow, and second to wetting the intermediate slag before resuming the blowing, at a cost ratio in the first and second portions {2-1): 1 and the total consumption of carbon-containing Mitial and 5-1 kg / t of steel, characterized in that, in order to increase the yield and reduce the cost of steel, as e carbon-containing and slag-thinning material using high-ash steam coal. the content of 4d-50 wt.% ash at 25-30 wt.% aluminum. 3-5 wt.% oxides of alkali-hemlene elements and 0.01-0.1 wt.% sulfur ..