SU1108763A1 - Method of melting steel - Google Patents

Abstract

METHOD OF MELTING STEEL in a converter with a combined pro-; ... ... 2 ....: a duvka, including loading a solid charge and scrap metal, pouring iron and supplying oxidizing gas and fuel from above to the surface of the melt and below to the level of the melt, from the fact that, in order to increase the proportion of scrap metal and eliminate emissions during the pouring of pig iron, the solid charge and scrap are preheated, and immediately before casting the pig iron the heating of solid charge and scrap is performed by supplying through the bottom tuyeres fuel in the amount of 1.5-6.0 kg of conditional i (L Fuel per 1 ton of scrap loaded and air at the same time) With a consumption of 50-100% of the flow rate required for complete combustion of the fuel.

Description

The invention relates to the production of steel and can be used in converter shops.

Recently, steel production in converters with a combined blowing with a drift and upper or side tuyeres has become widespread. Thanks to this, it became possible to replace outdated open-hearth furnaces with converters. - However, the replacement will require an increase in the share of scrap in the composition of the metal charge.

Known converter methods for the production of steel with

00

scrap consumption in the charge, including scrap preheating in

About the converter with the supply of gaseous 00 or ldsdkogo fuel and oxidizer through the bottom or upper tuyeres.

Ndgrev s.podayu fuel and oxidant only bottom tuyere, which is listed in the analogues, has the disadvantage. Conclusion in the backlog of heating the upper and middle layers of the charge compared to the bottom. At the same time, heating with fuel supply and oxidizer only the turn of the upper tuyeres, on the contrary, leads to overheating and intensive scaling of the upper layers as compared with the lower and middle layers.

The closest to the described invention to the technical essence and the achieved result is a method of steel smelting in the converter with j combined blowing, including: loading of solid charge and scrap metal, pouring pig iron and supplying oxidizing gas and fuel to the surface of the melt and from below to the bottom melt.

The disadvantages of the method are the limitation in the amount of scrap metal to be processed due to the absence of its preheating and the possibility of 5 emissions when pouring iron into the converter.

The aim of the invention is to increase the proportion of scrap metal and the elimination of emissions during cast iron. 20

The goal is achieved by the method, including loading the solid charge and scrap metal, pouring the cast iron and supplying oxidizing gas and fuel to the top of the melt surface and below the melt level, according to the invention, immediately before casting iron, additional homogenizing heating of solid charge and scrap is performed by feeding 1.5–6.0 kg of conditional fuel per 1 ton of loaded scrap metal through bottom tuyeres and at the same time, air with a flow rate of 50-100% of the flow rate necessary for complete combustion of the fuel.

The temperature in the combustion zone of the air-jet plume is 1100- 40 1300 C, depending on the type of fuel and the combustion conditions, and the temperature of the fuel-oxygen torch is 700 EOO C above (1800-230 C) also depending on the combustion conditions. Therefore, 45 when passing from the supply of oxygen to air, the likelihood of scrap melting and the formation of a liquid phase disappears.

With the transition from oxygen to air. 4-5 times the volume of combustion products increases. This leads to the fact that hot flue gases on the way to the throat of the converter tend to penetrate into all gaps and gaps between the each and every scrap pieces, as a result of which the heating of the inner part of the metal pool is intensified, other

In other words, the metal dumping is homogenized by temperature.

The optimal amount of fuel equivalent. The feed through the bottom tuyeres during the time of homogenizing heating of the charge is 1.56, 0 kg per ton of metal dumping. When feeding less fuel, the effect of the homogenization period is not significant. When the fuel supply is more than 6.0 kg / t, the period of homogenization is irrational due to the fact that with good alignment of the temperature the heat losses with waste gases significantly increase, and the process becomes economically unprofitable. For this reason, it is not advisable to supply air with a flow rate exceeding theoretically necessary for complete combustion of the fuel. If during the period of the main heating of the charge in the converter, puddles of molten metal were formed, then it would be necessary to freeze before pouring the iron. Dp of this air supply is conducted with a flow rate below 100%, theoretically necessary, for burning fuel. Part of the fuel (natural gas, fuel oil, etc.,) that is not burnt due to lack of air, decomposes under the influence of high temperature on low-molecular-mass compounds with heat absorption. Air supply with a flow rate of less than 50% required for complete combustion is impractical due to the absence of the effect of homogenization of the mixture in terms of temperature.

Below are examples of specific implementations of the method of steel in the converter box 10 tons.

PRI me R 1. The converter is loaded with 0.5 tons of lime, 0.4 tons of bituminous coal and 7.5 tons of scrap metal. 6.0 natural gas and 10.0 oxygen are supplied through the bottom tuyeres, and 12.0 oxygen through the top tuyere. After 5-7 minutes of purging, the upper lance is raised, and Natural Gas (flow rate 3.0) and air (flow rate 30) are supplied along the bottom ones. After 5 min, the blowdown is stopped, 2.5 tons of pig iron are poured. And the cage is again flushed with bottom oxygen containers (flow rate 35m / min) and natural gas (flow rate 3.5m / gdan. PRI me R 2. A converter is charged with 0.5 tons of lime, 0.4 tons of coal and 7.0 tons of scrap metal. 6.0 natural gas and 10.0 m / min of oxygen are fed through bottom tuyeres, and on the upper lance - 12.0 oxygen. After three to seven minutes of purging, the upper lance is raised, and natural gas is supplied through the bottom lances (consumption 8, Cm / / in) and air (flow rate 40.0 m / min). After 6 min, the blowdown is stopped, 1 3 3 tons of pig iron are blown and the charge is again flushed down with a bottom tuyere; 01 with oxygen (flow rate 35) and natural gas ({flow rate 3.5 m / min) Upon reaching the required composition of the melt and temperature, the metal is drained from the converter into the bucket and bottled. Technical and economic advantages; the method compared to the prototype consists in eliminating metal and shpak emissions when purging cast iron and replacing 30-80% of the expensive and scarce cast iron cheaper scrap

Claims (1)

Method of steelmaking in a converter with combined pro- duvkoy ^2, comprising feeding the solid charge and scrap iron casting and feeding oxidizing gas minutes fuel on top of the melt surface and the melt from below, the level of T l and h and w and w minutes with the I that, in order to increase the share of scrap metal and eliminate emissions during casting, preheating of the solid charge and scrap metal is carried out, and immediately before casting, additional homogenizing heating of the solid charge and scrap metal is carried out by feeding bottom tuyeres of fuel in an amount of 1.5-6.0 kg of equivalent fuel per 1 ton of scrap and charged simultaneously with the air flow rate is 50-100% FLOW · da necessary for complete combustion.