SU1027223A1 - Method for converting crude iron in converter - Google Patents

Abstract

METHOD OF TRANSMISSION OF A CAST IRON IN A CONVERTER, including filling scrap, pouring pig iron, adding slag-forming materials, purging with gaseous oxidizer in the first period for 15-25 minutes for the entire duration of blowdown, downloading intermediate slag, blowing, discharging metal of slag metal, and using final slag previous smelting, marked by the fact that, in order to accelerate the heating and melting of scrap ,. to increase the safety of the staff, the final slag of the previous smelting is poured with scrap at a temperature of 50-250 C higher than (the amount of its melting in the amount of 0.25-0.50 of the weight of the scrap piled up, then the cast iron is poured and the bath is blown.

Description

The invention relates to ferrous metallurgy, in particular to methods for the redistribution of pig iron in converters. There is a method of redistribution of iron in the converter by pouring scrap and pouring iron, in which lime in the amount of 20-25 of the total consumption for smelting is left on the final slag of the previous slag before melting, then, 5 min. blown to a carbon content of 0.81, 0, and download the intermediate slag. After the slag is loaded into the converter, scrap is loaded and the bath is blown to a carbon content of 0,, 0b in the metal. The disadvantage of this method is the increased risk of working due to emissions from the converter when casting iron and increasing the time of scrap melting. The closest to the proposed technical essence and the achieved result is a method of redistribution of cast iron by filling scrap, pouring pig iron, lime additive, blowing with oxygen, in which after the metal is drained from the converter in the latter, 90-95 of the final slag is poured scrap, cast iron is poured in and the bath is blown off during 15-25. during the whole period of purging, after which 70-80 intermediate slag is drained and 50-60 lime is used at the beginning of the second period to melt 23. The disadvantage is This method is slow heating and melting of scrap, an increased risk of work on the service personnel as a result of metal and slag emissions when casting iron into the converter. In fact, only the lower part of the deposited scrap has contact with the molten slag. In addition, the temperature of the final slag after the filling of the scrap, although it decreases, however, local zones of high-temperature slag remain, where an explosion-like explosion is possible.

the nature of the oxidation of carbon in iron casting.

The aim of the invention is to accelerate the heating and melting of scrap, increasing the safety of the operating personnel.

The goal is achieved by the fact that according to the method of redistribution 1

its melted down.

When the slag is discharged in an amount of more than 0.50 by the weight of the scrap piled up, it results in emissions from the converter due to an increased bath temperature. Pouring the cast iron after slag discharge and subsequent bath purging allows to conduct the process without emissions and pig iron in the converter, including filling scrap, pouring iron, adding slag forming materials, purging with gaseous oxidizing agent in the first period for the entire duration of the purge, downloading intermediate slag. , the release of metal and the final slag, as well as the use of the final slag of the previous smelting, the final slag of the previous smelting with a temperature of 50-250 ° С above its melting temperature is poured onto the scrap In the amount of 0.250, 50 of the weight of the scrap piled up, then cast iron is poured and the bath is blown. The pouring of the final slag of the previous smelting makes it possible to preheat and accelerate the melting of the scrap when it is dumped into scrap. At the same time, heating of scrap and slag goes into an inert state, which ensures the prevention of emissions during the process of pouring iron into the converter. Heating of scrap is achieved due to the even distribution of high-temperature slag when it is scraped into scrap, since scrap practically takes up more than 3 volume / volume of converter. The final slag of the previous smelting must be poured into the converter with a temperature of 50-250 ° C above the melting point of the slag. Slag pouring at a temperature of less than 50 ° C is impossible due to the high viscosity of the slag, moreover, this temperature does not provide sufficient pre-heating of the scrap, which hinders its melting. The slag pouring is more than 250 ° C, although it improves the conditions for scrap heating, but it dramatically increases the danger of you (Cables from the converter when casting iron, due to the formation of local zones of high-temperature slag in the converter. The final slag must be cast in the amount of 0.25-0.50 by the weight of the scrap piled in. When the slag is discharged in an amount of less than 0.25 from the weight of the scrap piled in, no heating and acceleration

metal nozzles and slag from the converter, intensify the decarburization process by accelerating the melting of scrap and increasing mass transfer.

Thus, the use of a lipeflozhennogo method for the conversion of pig iron in the converter provides for accelerated scrap scrap and safety of work of the staff.

Example 1. Preliminary calculation of the charge for smelting.

To melt 1 kg of metal, the heating of the metal to a temperature of 1b50 ° C (temperature of metal release from the converter) requires heat of 0.167-1500 + b5 + +0.2 (1650 - 1500) X 1 3 6 kcal, where 0.167 is the average heat capacity of Scum from 0 ° С to melting point, kcal / g);

0,2-average: heat capacity of liquid steel, kcal / g-O /;

65 - hidden heat of steel melting, kcal / kg.

Considering that converter slag is poured into converter in scrap in an amount of 50.0 tons at a temperature, and after the first period the output; 11 intermediate slag is discharged in an amount of 50.0 tons at a temperature of 1350 ° C, then the amount of heat absorbed by the bath from the final slag will be equal to 3,725,000 kcal: o, 298 -1600 + 50) 50,000 - (0.298 1350 + 50 X50000 3725000 kcal, where 0.298 is the average heat capacity of the liquid slag, kcal / {kg- ° C /.

If we neglect the heat loss by the converter during the discharge of slag and pig iron, then due to this additional heat, the scrap can be further melted down by 10.8 tons.

3,725,000: 10,800 kg or 10.8t.

The normal smelting charge for smelting low-carbon steels is 110 tons of scrap and 290 tons of cast iron at a temperature of 1430 ° C. Considering the heat introduced by the slag, the following melting charge is accepted: 120 tons of scrap and 280 tons of pig iron at a temperature of 1f30c,

8 tons of lime were added to a 350-ton converter, 120 tons of scrap were poured, and 50 tons (0, by weight of scrap) of the final converter slag of the previous smelting with temperature, which exceeds the melting point of the slag by, were drained. After draining the slag converter three. times shook with a view

uniform distribution of the loaded charge materials, and then poured 280 tons of pig iron with a manganese content of 0.25% and a temperature NZO ° C. The content in the iron of steel elements is: 0.50% silicon, 0.072% phosphorus, 0.017% sulfur. Purging was performed with a four-nozzle lance with an oxygen flow rate of 600-700 m / min with a variable position of the tuyere at a /) bath level. The purge in the first period was carried out for 7 minutes at the position of the lance 1.2m (for selsyn), then the purge was stopped, the converter was tilted, and 50.0 tons of slag were downloaded at 1350 ° С. After downloading the slag, the converter was turned into a vertical position, 6.0 tons of lime were added, and the purge was continued at the position of the lance 1.2 m for 8 and. 10 min total duration

0 another 3.0 tons of lime and for 12 minutes of purging lowered the lance to 0.8 m.

The purge was completed with a carbon content of 0.08% and temperature. The content of sulfur and phosphorus in the metal was, respectively, 0.008 and 0.006%,

The total consumption of lime for smelting was 20 tons, oxygen 17500 m of slag 50 tons. The pouring of the liquid converter slag proceeded quietly without emissions of metal and slag. The notice of the tuyere and the vapor tract was not detected. The content of the final slag .20,0%

5 with a basicity of 4.8. Slag melting point.

Example 2. Similarly to the example.

1 carried out the calculation of the mine in the filling.

350-tnn converter attached

0 8.0 tons of lime, poured 118 tons of scrap and poured 58.5 tons (0.50 of the weight of the final converter slag of the previous melt with temperature, which exceeds the melting point of the slag by. Then 283 tons of Guna gun with manganese content of 0, 25%, phosphorus O, O72%, sulfur 0,017% and silicon 0.51% at temperature. The lance was conducted by a four-tuyere tuyere with a nozzle outlet diameter of 57 mm at a position of 1.2 m for the tuyere (for the absinth) for 7 minutes, then stopped blowing, tilted converter to download slag. Slag 5 was downloaded in the amount of 58.5 tons at a temperature of 1350 ° C. After approx nchani intermediate shla1 {a perch 6 tons of lime and continued to purge with at

Claims (1)

METHOD FOR TRANSFER OF PIG IRON IN THE CONVERTER, including scrap filling, cast iron casting, doping of slag-forming materials, blowing with a gaseous oxidizing agent in the first period for 15-25% of the total blowing time, downloading of intermediate slag, purging, exhausting metal of the final slag, as well as using final slag of the previous melting, characterized in that, in order to accelerate the heating and melting of the scrap. to increase the safety of the staff, the final slag of the previous smelting is poured onto the scrap with a temperature of 50-250 ° C above its melting temperature in the amount of 0.25-0.50 of the weight of the scrap scrap, then cast iron is poured and the bath is blown.