SU1595922A1 - Charge for producing steel in oxygen converter - Google Patents

Abstract

This invention relates to metallurgy, in particular to the production of steel in a converter. The purpose of the invention is to increase the technical and economic indices of the process by reducing metal losses with emissions, increasing the degree of phosphorus and sulfur removal and reducing the melting time by achieving the charge for steel in an oxygen converter consisting of scrap metal, molten iron, lime, fluorspar and heat carrier containing silicon carbide, introduced carbon-carbon carbide material in the following ratio of components, wt.%: scrap metal 27.7-33.2

lime 7,10-7,24

fluorspar 0,22-0,24

carbon-carbide material 0,28-0,32

cast iron - the rest. 1 tab.

Description

This invention relates to metallurgy, in particular to the production of steel in a converter.

The aim of the invention is to increase the technical and economic indicators of the process by reducing metal losses with emissions, increasing the degree of phosphorus and sulfur removal and reducing the purge time.

The technological process of production of graphite electrodes idu-. These types of graphite products provide for one-stage heating of the material without air access to 2200-2800 C in special electric furnaces. To more evenly distribute heat and prevent oxidation, electrode products are filled with highly ash carbon material mixed with quartz sand. When this furnace is loaded into the furnace in this way, the thermal energy released during the passage of electrodes and other products of electric current through the stack is spent on graphitizing carbon materials and heating has been combined with

The contact material with the backfill material is up to 2AOO-2800 C. At the end of the graphitization of electrodes or other products, the curved material is a carbon-oxo-carbide - the 1st material - a waste product.

The carbon dioxide material contains, May. % 5 Sic 15-40; Si 1-15; A1GPZ 1-15; FeO 1-10; MgO 1.5; -. CaO 1-5; With the rest,. It was found that the combined use of silicon carbide and carbon to increase the temperature has lisico-chemical features that distinguish the use of the proposed coolant from the use of pure SiC for this purpose and in the aggregate

with Si.

The proportion of heat introduced by the oxidation reactions of carbon and silicon is 40-45% and 25-30%, respectively, in the heat balance of smelting, with a significant proportion of the heat of oxidation of silicon occurring during the period preceding the intensive oxidation of carbon. During this period, the proportion of silicon and its compounds in the heat balance is 70-75%. With a higher consumption of scrap metal, when carbon oxidation slows down due to significant overcooling of the bath, the role of silicon as the primary coolant increases.

By simultaneously introducing the calcined silicon carbide and carbon, it is possible to achieve the following result. The use of silicon carbide (together with carbon) performs not so much the function of one of the heat sources to increase the heat content of the bath, but rather the function of a different thermal ignition of the temperature increase necessary for the start of intensive oxidation of carbon (t.

The use of calcined gas, as a result of the oxidation of which 242000 kL / kg Sic is released (for silicon, this value is 32966 kP / Si), significantly approximates the start time of the purge and the start time of the intense oxidation of carbon

The ratio between the mass and carbon content of silicon carbide in a carbon-oxygen-carbide material, W-2-6-2.8, allows by the time of the beginning of intensive oxidation of carbon

Yes, the SiC content in the bath is close to zero, while the carbon content is practically not reduced, as a result of which the further heat flow into the converter bath is due to carbon oxidation reactions. This provides a stable SiO content. in the slag, and hence its basicity. A rapid temperature increase in the initial period of purging leads to early slagging. Homogeneous, highly basic slag r is formed already for 2-3 minutes of purging.

The mixture of calcined C and Sic has a number of properties that distinguish it from non-calcined carbon-containing materials: high, specific porosity, low degree of contamination of various impurities, which greatly contributes to the oxidation of carbon and silicon carbide. The rate of these reactions significantly increases, which means that the amount of heat released per unit time. The blowdown time is reduced by 0.8 minutes.

The use of carbon-carbide material is also due to the fact that its introduction into the bath in the amount of 3.0-3.5 kg / ton significantly improves the conditions for slagging.

The main source of slag formation in the oxygen-converter vessel during the process is lime. A more complete and rapid dissolution of lime and the formation of slag of the desired composition is greatly facilitated by the preliminary preparation of slag-forming materials.

The use of lime containing oxides of other metals (MPO,, FeO), introduced by carbon-carbon carbide material, significantly accelerates its transfer to pshak, as a result of which the yield is good and the degree of removal of harmful impurities (phosphorus and sulfur) from the metal increases.

Entering carbon-carbide material into the charge is expedient in the amount of 0.28-0.32% (3.0-3.5 kg / t). With a decrease in its consumption of less than 28 28% (3.0 kg / t), the thermodynamic conditions of slag formation are significantly worsened. In addition, due to increased specific scrap content, the likelihood of converter closure sharply increases. With a magnified 40

In this case, the carbon dioxide content of the carbonaceous material in excess of the specified limits of the bath temperature at the end of the purge is much higher than the optimum one.

With the use of scrap metal in the amount of 33.2% (36%), as well as with a reduced content of carbon dioxide material, the thermodynamic conditions of slag are significantly worsened. And when using scrap in an amount of less than 27.7% (30%), the bath temperature at the end of the purge considerably exceeds the optimum one.

The use of fluorspar in the amount of 0.22–0.24% (2.4–2.6 kg / t) ensures optimal viscosity, high activity of iron and calcium oxides, etc. An increase in its consumption above the specified content leads to an excessive decrease in the viscosity of the slag, which causes poor slag separation from the metal and, consequently, large losses of metal with slag. In addition, the increased consumption of fluorspar significantly affects the economic performance of smelting, how it is expensive and scarce. A decrease in its consumption causes the viscosity of the slag to be significantly higher than the optimum, which, in turn, leads to a low transition to the slag of phosphorus, sulfur and non-metallic inclusions.

A decrease or increase in lime consumption in excess of 7.10–7.24 (76.9–78.1 kg / ton) does not ensure the basicity of the donkey, which is optimal for the occurrence of defosfradium reactions, moreover, the lime consumption above the right limit sharply reduces its assimilation i.e. Higher lime consumption does not increase the efficiency of its impact, but also increases the amount of slag produced, which leads to metal losses with removals and additional heat consumption for heating, melting and maintaining the slag in the liquid state, I

PRI mery Under laboratory conditions, a comparative analysis was made of the technical and economic indicators of the process of obtaining in the steel converter from the proposed charge and the prototype charge.

After the steel was rolled up, metal scrap was loaded into the converter, a small amount of lime (10–12 kg / ton) and half of the total amount of heat carrier — carbon dioxide material. Then, liquid iron, heated to 1305-1415 C, was poured into the converter, and purging was started. 2-3 minutes after the start

Purges were applied to 70% of the remaining carbonoxycarbide material and about the same amount of lime (the remainder of the lime and carbonoxycarbide material was placed in

after 5-7 min purge).

The results of the tests are summarized in the table.

The use of the proposed composition of the mixture to obtain steel in the con- (

A helicopter can significantly improve the efficiency of the process. This increases the degree of desulfurization and dephosphorization by 4.5 and 1.7%, respectively, and the blowing time is reduced.

by 0.8 min and the increase in the scrap ratio in the charge by 5.36%.

Firma of the invention Fir for steel production in an oxygen converter, including scrap metal, liquid iron, lime, fluorspar and heat carrier, silicon carbide content, which in order to improve the technical and economic indicators of the process by reducing the time of purging and increasing the degree of removal of sulfur and phosphorus, carbon dioxidecarbide material was introduced as a heat carrier in the following ratio of components,

wt.%:

Metal scrap 27.7-33.2 Lime7.10-7.24

Fluorspar 0,22-0,24 Carbon-doxycarbide material 0,28-0,32

Indicator

scrap possession, X cast iron possession, X lime lime, I / kg / g fluorspar asphalt, S / kg / t Fe-Si slag production, X

kg / t Carboxycarbide consumption

X material, Cao Particularity shpak, In -gj

Cast iron pouring temperature, С

Metal temperature at the end of the purge

Daphophsfraction degree, X Desulfurization degree, Z. Purging duration, mic Carbon content in finished metal, 2

1Sulfur sulfur in the finished metal, X

Phosphorus content in lb metal, X FeO content in a donkey, X

25.0923.99

The rest is still

6,987.01

0,250,20

0.13

33.20

The rest is the rest

7,247,84

0,240,26

Claims (1)

Formula of the invention Fir for production of steel in an oxygen converter, including metal scrap, molten iron, lime, fluorspar and heat carrier containing silicon carbide, characterized in that, in order to increase the technical and economic parameters of the process by reducing blowing time and increase the degree of removal of sulfur and phosphorus, carbon-carbon carbide material was introduced into it as a heat carrier in the following ratio of components, May 45 "% · Scrap metal 27.7-33.2 Lime 7.10-7.24 Fluorspar 0.22-0.24 Carbon Dioxide material 0.28-0.32 Cast iron Rest Indicator Receipt process steel from charge prototype proposed -: 1 I 2 1_l__ I ’ Loya content. X 25.09 23,99 27.70 30.45 33,20 35.99 - Cast Iron Content, X Rest Rest Rest Rest Rest Rest Lime consumption, X / kg / t 6.98 7.01 7.10 7.17 7.24 7.84 Flux board consumption, X / kg / t 0.25 0.20 0.22 0.23 0.24 0.26 Slag consumption of Re-Zx, X kg7t and, I O Carbonoxycarbide consumption X material . - 0.52 0.28 - 0.30 0.3¾. .0.24 Slag basicity, In 3.27 . 3.61 3.48 3,51 3,59 3.02 Cast iron pouring temperature, ° С 1409 1411 1410 1410 1410 1409 Metal temperature at the end purge 1610 1630 1608 1612 1609 1578 The degree of dephosphorization, X 91.3 91.4 93.8 94.1 93.7 86, A The degree of desulfurization, X 26.7 36.7 39.5 45,2 - 40.1 25.9 Purge Duration, min 17.1 16.3 16.3 16.3 16.3 17.8 Carbon content in the finished metal, X 0.15 0.27 0.13 0.15 0.16 0.11 Sulfur content in finished • - - .. metal, X 0,020 0.019 0.018 0.017 0.017 0,031 The phosphorus content in the finished metal, X 0.0069 0.0071 0.0057 0.0053 0.0054 0.0121 7 ReO content in the joint, X 12.8 12.9 12.7 12.5 12.7 13.5