SU1219657A1 - Powder-like refining mixture - Google Patents

Description

one

This invention relates to ferrous metallurgy, in particular to steelmaking with metal blowing through powdered materials.

The purpose of the invention is to adjust the chemical composition of the metal over silicon and increase the refining capacity of the mixture.

- In the powder mixture, including lime, fluorspar and aluminum, additionally introduced silicides of rare-earth metals in the following ratio, wt.%:

Silicides of RZM 2,0-4, 5 Aluminum 5,0-15,0

Fluoric

spar5.0-10.0

LimeEverything

The introduction of rare earth silicides into the composition of the proposed mixture makes it possible to adjust the chemical composition of the metal with silicon, while simultaneously improving the refining capacity of the mixture with respect to sulfur, which contributes to the achievement of a low sulfur content (0.002-0.003%) in the metal.

The composition of the proposed mixture was developed on the basis of the results of experimental melting with the injection of powders into metal, conducted in an open induction furnace.

The mixture is prepared as follows. The materials are crushed and sieved to a fraction of not more than 1 mm, lime and fluorspar calcined for 1 h at 600-650 ° C, then the materials are mechanically mixed. Purging with prepared mixtures is carried out in a stream of argon at a flow rate of 0.1 and a pressure in the pneumosupercharger not exceeding 3 atm. Consumption of powdered refining mixtures 1% by weight of the metal. The duration of the purging defect 2 min in all experienced swimming trunks. Metal temperature is 1600-1620 ° С. The content of the main elements in the metal before purging,%: From 0.25-0.30 About 0.0088-0.0096; Si 0.18-0.20; MP 0.23-0.26; S 0,050-0,056.

Metal treatment efficiencies with mixtures of different compositions are determined by the content of silicon, sulfur, oxygen and non-metallic inclusions in metal samples taken before and after blowing with powders.

In determining the optimal composition of powdered refining

96572

the mixture revealed that the content of silicides of rare-earth metals 2.0-4.5 wt.% allows you to adjust the chemical composition of the metal with silicon, and also contributes to the process of desulfurization of steel. When the content of rare-earth silicides in the mixture is less than 2.0%, the amount of silicon going to doping decreases, and the degree of desulfurization decreases. The increase in the content of silicides of rare-earth metals in the mixture (more than 4.5%) is impractical, since there is a danger of getting the silicon content in the metal above the brand, except

moreover, the degree of desulfurization is not increased.

To increase the oxidative capacity of the mixture, 5-15 wt.% Aluminum is introduced into it. While decreasing

The amount of aluminum in the mixture is less than 5 wt.%, The deoxidizing ability of the mixture decreases, and the consumption of rare-earth silicides for deoxidation increases. Use of REM silicides

5 as a deoxidizing agent is inexpedient, since their solubility in the metal is low compared with aluminum; moreover, the amount of REM silicides, which is spent on the alloying of steel with silicon, decreases. An increase in the amount of aluminum in the mixture of more than 15 wt.% Does not affect the further reduction of oxygen in the metal, but at the same time, the contamination of the steel with non-metallic alumina-based inclusions increases.

The introduction of 5-10 wt.% Of fluorspar into the mixture ensures the production of liquid slag, which contributes to the refining of the metal from sulfur and non-metallic inclusions. When reducing the content of fluorspar less than 5 wt.% Decreases the liquid mobility of the slag and

45 the steel desulfurization process is deteriorating. An increase in the fluorspar content of more than 10 May. 7 is not advisable, since the liquid mobility of the slag does not increase.

The addition of lime to the mixture provides an improvement in the technological parameters of the slag, i.e. its basicity, desulphurisation capacity, increases, which contributes to improving the refining capacity of slag from sulfur and non-metallic inclusions.

0

five

0

The compositions of the proposed and known powder refining mixtures are given in table. one .

Experimental melting was performed with the indicated mixtures.

The results of metal processing by mixtures are presented in Table. 2

The metal treatment offered by powdered refining mixtures (2-A) allows the metal to be doped with silicon, and also contributes to an increase in the degree of desulfurization, a decrease in the oxygen content and non-metallic inclusions in steel to a lower content than when treated with a known mixture.

The proposed mixture tested in the smelting of structural steels. After the release, the metal in the ladle is blown in a stream of argon at its pressure

0.0540.02946.2

0.0530.03043.4

0.0540.03044.4

0.0530.02258.9

0.0520, 5

NII in argonpipe not less than 8 atm. Argon consumption 0.25, mixture consumption 1% by weight of metal. For comparison, the metal is treated with a known mixture.

The results of the processing of steel proposed mixture and known are given in table. 3

Thus, the use of the proposed mixture provides an adjustment of the steel's iron hardening composition, achieving a consistently low sulfur content in steel, and a way of reducing the content of non-metallic inclusions. In addition, during the smelting of structural steels, the duration of melting is reduced, and the consumption of aluminum and ferrosilicon is reduced.

Table 1

table 2

0.044 0.031

0.030 0.015

Continuation of table 2

Table 3

0,0100,00280,0

0,0110,00645,4

0,0120,00833,3

0,0140,00564,2

0,0120,00650,0

Compiled by K. Sorokin Editor V. Petrash Tehred I.Popovich Proofreader A. Ferenc

Order 1236/37 Circulation 552Subscription

VNIIPI USSR State Committee

for inventions and discoveries 113035, Moscow, Zh-35, Raushsk nab., d, 4/5

Branch PPP Patent, Uzhgorod, st. Project, 4

Continuation of table 3

1.04

1.11

0.027

Claims (1)

POWDER-REFINING MIXTURE, including lime ^ fluorspar and aluminum, characterized in that, in order to adjust the chemical composition of the metal in silicon and increase the refining ability of the mixture, it additionally contains rare-earth silicides in the following ratio, wt.%! REM silicides 2.0 - 4.5 Aluminum 5.0 - 15.0 Fluffy spar 5.0-10.0 Lime Rest Q 5s SU „., 1219657>