SU969746A1 - Slag-forming mix for smelting steel - Google Patents

Description

The invention relates to ferrous metallurgy, namely the production of steel in converters.

Slag-forming mixtures are known, including lime and fluxing additives that intensify the process of lime dissolution and slag formation, such as lime and fluorspar, lime and bauxite, lime and manganese oxides 1.

The disadvantages of the known slag-forming mixtures are scarcity, high cost and low efficiency of slag formation.

Closest to the present invention is a slag-forming mixture of steel 2, including lime and a flux additive, and as an additive it contains flux of the following composition, wt%:

Calcium fluoride

Creme dioxide 10-30 nor 5-19

Alumina 0.5-6.0 Magnesium oxide 0.5-10 Iron oxides 0.01-1.0 Sulfur

Carbonated carbon

A disadvantage of this mixture is the high consumption of calcium carbonate (70% over the upper limit), for which a significant portion of the heat is consumed; in connection with atim, the proportion of the scrap in the metal mill is reduced.

The purpose of the invention is to accelerate the dissolution of lime, increase durability

10 lining and converter performance.

The goal is achieved by the fact that the slag-forming mixture for

15 steelmaking, including lime and a fluxing additive, contains a nepheline-feldspar product as a fluxing additive in the following ratio, wt.%:

20

Lime90-98

Nepheline-feldspar product2-10

25

The nepheline-feldspar product is a waste from the process of enrichment of polymetallic ores and has the following chemical composition, wt.%: 22.3-24.7; FejO 5.5-7.0;

30 NaiO 12.6-13.5; KeO 4.2-4.8; CaO 1.01, 5; HgO 0.7-1.0; TI Oj 0.8-1.0; P, OS 0,25-0,40; SIOj 48-49. When using as an additive for the addition of nepheline-feldspath product, there is an intensive dissolution of lime, a decrease in viscosity and melting point of slag due to the presence of Na and K oxides in it in a total amount of up to 20%, as well as SI0 content. As the S i Oji content in the slag increases, its composition moves from the heterogeneous region to the homogeneous melt region, which leads to an increase in CaO (C,), an increase in slag activity with respect to lime dissolution. This has a positive role for Si 02 in the slag formation process. The presence in the slag and contributes to an increase in the activity of iron oxides in the slag. MgO found in the nepheline polymer product, dramatically reduces the viscosity of the slag. The content of nepheline-feld product in the slag-forming mixture of less than 2% causes low dissolution rates of lime, and with a content of more than 10%, the amount of silica introduced into the slag increases noticeably and an increase in lime consumption is required for its fusion despite the rapid dissolution of lime. The test results of the slag-forming mixture for steelmaking are shown in the table. Industrial tests of the slag-forming mixture for steel smelting show that the optimum composition is the following ratio of components, wt.%: Lime 94 Nepheline-feldspar product6 When using this composition, slag-forming, its final basicity of slag increases by 13%, consumption the linings are reduced by 0.7 kg / t, the content of sulfur and phosphorus in steel is reduced by 0.010 and 0.005%, respectively, and the total duration of the purge is reduced by 2 minutes. The expected econoxy effect from the use of a slag-forming mixture of 0.2 Ruy / ton of steel.

ZD

94

Known

17

0.035 0.020

2.7

Claims (1)

 1. Yavoisky V.I. and others. Metallurgists of steel. M., Metallurgists, 1973, p. 154. 2, USSR Author's Certificate 487946, cl. C 21 C 5/54, 1976.