SU850679A1 - Slag-metal mixture - Google Patents

Description

(54) SLACOMETALLIC MIXTURE FOR REFINING

i

The invention relates to ferrous metaplurgia and can be used for out-of-furnace processing of steel in a ladle at its release from a steelmaking unit.

The use of shpakometapichesky mixtures for refining, pulverizing and alloying of metal is known. An exothermic slag-forming mixture containing aluminum, oxide, iron, CaO, Aba is used to descale the scientific research institute, cesulfurapia and remove non-metallic inclusions (HB). Oe, SiO2, CaFg,, MgO, MI About p ..

However, the mixture is highly basic, which implies an active interaction, j outside with the lining of the ladle and, as a consequence, the additional introduction of HB into the steel. In addition, in the case of the use of this mixture, the issue of saving ferroalloys, jp

Known slag metal mixture for metal refining, containing 5-7% of lime and 30-95% of electrothermal silumin production slag. Got off

the last one contains,%: ACjj. Oj45-58; SiO / j 3-10; Si 5-20; A 1O-25, 5i 3-12 and aluminum oxycarbide 1-10.

When a metapp is processed with this mixture, the content of impurities in it decreases and the consumption of deoxidizers 2J is reduced.

The disadvantage of this mixture is that when using its day of refining the metappad, the injected components of the mineral part do not contribute to an increase in the absorption of the epitheliosis. The composition of the mineral part of the known mixture is not beneficial for the assimilation of non-metallic non-metallic inclusions, the formation of negative inclusions of unfavorable form is not excluded. Nonmetallic inclusions formed during the working of a metal with a known mixture have a high melting point, which does not contribute to coarsening and removal from steel.

The slag metal mixture is known, consisting of alloy powders of 5-15%. MI of SO-5O% and Si) and 3s of poor manganese ore (65-7O% of the AMC alloy weight), which is used for oxidized steel NW. When using poor manganese ore, containing wt.%: E 19.3; Si O 14.8; Ca 14.8 Fe 5.96; shpakometappicheskii mixture has the following composition, wt.%: Aluminum 1.5-6.25 Silicon7.5-9.0 Manganese9-17.5 Iron Oxide 5.5.5-5.6 Silica 9.6-1O, 3 Calcium oxide 9.6 -10.3 Manganese Oxide 16.2-17.0 However, the mixture contains not more than 10.3 silica, and the ratio CaO / 5-i0 -1. those. slag is basic. In addition, the mixture does not provide for the deep degradation of the steppe and the necessary purification from non-metallic inclusions. The chain of the invention is to obtain an additional effect when using i mixture - reducing the consumption of racial elements: acidifiers, primarily manganese, and the content of nonmetallic inclusions. This goal is achieved by the fact that the slag metal mixture for refining steel, including aluminum, silicon, manganese, iron oxide, Silica, Calcium Calcium, Manganese Oxide, contains the following components, wt.%: Aluminum 2-12 Silicon 2-6 Manganese 1 O-24 Iron Oxide 0.1-1.0 Silica C3 Calcium Oxide 6-2 O Manganese Oxide 5-2 Processing gishy st with a mixture of the present composition provides glubokoraskislennoy STAP with minimal especially harmful for fatigue tests nonmetallic zkt1yucheny AE type 2 OZ including -trochechnyh inclusions. Any steel inevitably contains oxide nanotubes, which are formed mainly by hardening at the moment of introduction of deoxidation of metals, the time of hardening of steel and as a result of the destruction of refractories. The occurrence of zhidnyh HBs directly in the ingot is highly undesirable, since these are difficult to remove and are distributed unevenly in the volume of the metal. In order to suppress the process of the formation of oxide HBs in an ingot, deep cleavage is necessary, which should ensure the oxygen solubility by the time of solidification less than the limit of its dissipation in solid iron (0.003%). A reduction in the content of less than 0% OO1% greatly enhances the processes of secondary oxidation during steel casting. In the composition of the proposed mixture, 2-12% AE provides obtaining of oj in precursors O, OO1 0, 003%. The introduction of silicon and manganese into the mixture provides non-metallic inclusions in steel with a favorable composition. When the ratio of manganese introduced. to the silicon introduced equal to 2.5 and more, liquid silicate inclusions are formed. These inclusions are fusible, coagulate well and are easily removed from steel. The aluminum introduced into the metal is consumed for the binding of dissolved oxygen. The less it is consumed for this purpose, the less oxide is formed. The oxidation of aluminum depends on the content of iron oxides in the induced slag. Thus, with a content of 15% FeO in the slag, the oxidation rate of aluminum reaches 0.0015% / min, and in the case of a content of up to 1%, the oxidation rate decreases by a factor of 15 and is O, OOO1% / min. The content of FeO in the proposed mixture is limited to 0.1-1%. A decrease in the FeO content in the mixture below 0 ° C, 1% has almost no effect on the oxidation rate of aluminum, while the use of materials with such a low GeO content leads to an increase in the cost of the mixture. Oxide HBs are also formed as a result of the destruction of refractories. This kind of inclusions. It is a very dangerous consequence of their large size. Therefore, the slag brought in during processing should be the least aggressive to the fireclay lining of the ladle, at the same time a light-melt CIM (Tp | no more) and flowable (at 1550С viscosity not more than 5 П). Slag must assimilate well HB and have the least adhesion to the liquid metal. The latter is necessary in order to reduce its entanglement in the metal. Such conditions are best met by an acid base shpak with a 5iO2 content of 30-60%; CaO 6-2O% and basicity not higher than O, 5. The introduction of a mixture of Mi O with not less than 5% ensures that the melting temperature of the obsease slag is below 1350 ° and the viscosity is less than 2 P at processing temperatures

metal. An increase in M and O content above 20% MPO affects the melting temperature and viscosity of acid slags, therefore, in the composition of the recommended mixture, the content of MI O is limited to 5-20%.

Conjugation in the igpacommetric mixture of deoxidizing elements and their oxides

in the presence of a nonanachigular amount of FeO spsp; it is more active in rec. ay of oxygen from metal to the slag phase, complying with the law of the distribution of the elements between metape and shpak. Thus, the proposed slag mix ingin1 "identifies the process of deoxidation.

PR in m and r. In the inoculation furnace with a capacity of 6O kg, smelting was carried out with the treatment of steel with the proposed slag-and-mash mixture. The chemical composition of coated steel, wt.%: C 0.3-0.4; Mi 0.25-0.35; Si O, 2-O, 4; 5 O, O16O, O25; P O, O16-O, O2O; iron else. Treatment temperature CTQ; IH l (3OCfc amount of the mixture 2% by weight metpppp.

In tab. Figure 1 shows the pre-burn composition of the mixtures and the absorption of manganese oxide (Mie O). In tab. 2 the content of non-metallic inclusions (HB) and their chemical composition are presented.

In tab. 3 shows the composition of the proposed mixture in comparison with the known.

Thus, with an increase in the aluminum content of the steel, the recovery of manganese from oxides increases. However, the determination of the content of nonmetallic inclusions in the metal showed that an increase in the aluminum content in the slag-metal mixture of more than 12% leads to an increase in the contamination of steel with inclusions of the type that are very dangerous during wire drawing.

As a result of processing the steel with the known and proposed mixture, a decrease in the content of nonmetallic inclusions by 30% was obtained, in particular for alumina inclusions by a factor of 2-3.

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Table

8506798

Continued table. 2

Claims (3)

1. Japanese Patent No. 49-5128, cl. 10 L 154, 1969. 2. USSR author's certificate number 467941, cl. C 21 C 5/54, 1974. 3. Metappurga manganese. Tbilisi, 1977, p. 236-237.