SU1104165A1 - Charge for obtaining synthetic slag - Google Patents

Abstract

1. CHARGE TO GET A SYNTHETIC SHPAK, including lime, alumina-containing material and reducing agent, characterized in that, in order to increase the plastic properties of steel, it additionally contains bastnesite in the following ratio, wt.%: Alumina-containing material 5-20 Reducer 5-20 Bastnesit 5-30 Lime Rest 2. The mixture according to claim 1, characterized in that. Bastnesite has the following chemical composition, wt%: cerium 30-41% Total of other rare earth metals oxides 34-37 g Carbon dioxide 18-22 Fluorine .3.0-8.5 (L

Description

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1 Invention relates to metallurgine, specifically to the production of slags of a special composition intended for use in the production of steels by mixing molten steel billets obtained in one melting unit with deoxidizing and alloying alloys, produced jointly with synthetic slag in another melting unit The known charge for smelting the synthetic donor LU, including, in May, the production of electrocorundum 20-30 Spent synthetic slag 12-20 Known for the Other The disadvantage of this mixture is With t that obtained with its use has become low rates of strength and ductility. For example, for ZOHGSA steel, the tensile strength of 6g does not exceed 100 kgf / mm, the yield strength of bu 90 kgf / mm, the relative elongation O is not more than 8%, the relative narrowing of C is not more than 12%, the impact strength of ac + 20s is not more than | 1.5 kgcm / cm. Closest to the invention is the charge for the production of synthetic slag of the following composition, wt.%: Alumina-containing material 20-40 Lime1-40 Reducing agent 0.5-10 Dump steel-smelting slag Else Using synthetic slag obtained from this mixture avoids slag foaming , since as a reductant, instead of coal of the purer, it may be used in the amount of 1-5% or aluminum in the amount of 0.5-1.0% Y. However, obtained with the use of known charge steel have insufficient plasticity indicators. For example, for a given brand, the relative narrowing became (f does not exceed 51%, the relative elongation is about 15.5%, and the impact strength, and, | +20 C is not more than 6.6 kgf-m / cm. This is because the desulfurizing ability of synthetic slag is not high enough (the degree of desulfurization does not exceed 40-50%) 52 due to the use of dump steel-making shpaks containing an increased amount of sulfur in the mixture. The aim of the invention is to increase the plastic properties of steel. The goal is that the mixture is to produce synthetic slag , including lime, alumina-containing material and reducing agent, additionally contains bastnesite in the following ratio, wt.%: Alumina-containing material 5-20 Reducing agent 5-20 Bastnesite 5-30 LimeExtra And bastnesite has the following chemical composition, wt.%: Cerium oxide 30-41 The sum of other oxides of rare-earth metals34-37 Carbon dioxide 18-22 Fluorine .3.0-8.5 Rare-earth metals are reduced from bastnesite when interacting with a reducing agent to reduce impurities, including sulfur, th and modifying steel. The limits of the content of the reducing agent (aluminum) are determined by the consumption of bastnesite, lime and alumina-containing slag - the need to induce highly basic aluminous slag. The introduction of more than 30% bastnesite into the mixture deteriorates the plastic properties of steel, since brittle intermetallic iron compounds with supercoe l and metals are precipitated at the grain boundaries in steel, which, in turn, leads to deterioration of the mechanical properties of the steel B produced. The introduction of less than 5% bastnesite into the mixture (as shown by melts) did not lead to an increase in plastic properties, since the effect of steel modification due to the low content of rare earth metals in it is not observed, which also does not allow an increase in the degree of metal desulfurization. During the industrial testing of the proposed mixture, the following compositions were prepared, given in the table .. where compositions 1-3 are proposed: 4 below the lower limit, 5 — above the upper limit of the bastnesite.

The composition of the mixture was worked out upon receipt of silicon, chromium-manganese containing steels.

In the preparation of the mixture, all components were uniformly mixed and then fed into the furnace for slag-forming,

Example. Production of silicon-chrome-marg4-containing steel ZOHGSA using the proposed mixture. Open-hearth steel billet (smelting H2-9374) is smelted in the main open-hearth furnace with a capacity of 70 tons according to the existing technology in the enterprise.

Liquid alloy and synthetic slag were prepared in a 12-ton electric furnace.

During the smelting of the alloy into the furnace, it was loaded, kg: waste steel 2000J ferromanganese Mnb 680, ferrochrome PF 800 680, ferrosilicon 45% 1450. Total: 3810kg

 To prevent the charge components from oxidizing, 300 kg of lime was loaded into the electric furnace during smelting.

After melting, synthetic slag began to be induced in the electric furnace. For slagging, materials are fed into the furnace in accordance with the specified mixture of composition 2 (Table 1) in an amount of 1350 kg (including lime, given in melting).

The resulting synthetic pshak had

the following chemical composition,%: calcium oxide 47.5i silica 8.12 alumina 31.72) magnesium oxide 8.32, titanium oxide 1.03 iron oxide 0.37 manganese oxide 0.6, CejO 1.2 (La, PrJjO 1.12.

The chemical composition of the liquid master alloy after the release is as follows,% carbon 2.12 manganese 9.82; chromium 9.87, silicon 11.82, oxides of rare-earth metals 1.78; iron the rest

Before the open metal, before the extrusion, it contained% carbon 0.17, manganese silicon 0.21, chromium 0.17J sulfur 0.025., Phosphorus 0.013f molybdenum 0.01; Nickel 0.25; copper 0,22, iron else.

After the opening of the open-hearth billet and its processing with a synthetic putty and liquid alloy, steel was obtained that meets GOST 4543-71 and has the following chemical composition by mass%: carbon 0.31; manganese 1.03; silicon 1.01, phosphorus 0.015, sulfur 0.011; chromium 1.00; Nickel 0.24; copper 0.21; molybdenum 0.01 Ce (La, Pr) 0.0

For comparison, ZOHGSA steel was also obtained using a known mixture for the production of synthetic fiber (fusion H5-2192),

Also melted melting using the mixture of composition 4 (melt H5-2202) and the mixture of composition 5 (melting NZ-7567) with the content of bastnesite in the mixture of 4.5 and 32% cooTBefcTBeHHo.

Data on the mechanical properties and degree of desulfurization of ZOHGSA steel using different mixtures of the mixture listed in Table. 1, are presented in table. 2,

The use of the proposed grinder, as compared with that known for producing synthetic slag, improves the relative elongation and impact strength by 56%, the relative narrowing by 14% for the specified steel grade while maintaining the strength properties at the same level.

Table 1

30/600

5/100 20/270 13.5 / 182

5/120

20/480 4.5 / 108 15/360

32/710

9.5 / 212

2000

45/900 51/689 1350

70/1680

2400 75/1800 2400

38/844

20/444

2220 H2-9378,124.2 116.130.6 H2-9374129.3 117.234.6

Table 2 56,29,360,0 60,1. 10,156,4

Claims (3)

1. Batch for the production of synthetic slag, including lime, an alumina-containing material and a reducing agent, characterized in that, in order to increase the plastic properties of steel, it additionally contains bastnesite in the following ratio of components, Alumina-containing material Bastnesitis 5-20 5-20 5-30 Lime Else 2. The mixture according to claim 1, characterized in that. bastnesite has the following chemical composition, wt.%: Cerium Cerium 30-41 Sum of other rare earth metal oxides · Carbon dioxide Fluoride 34-37 18-22 3.0-8.5