SU971573A1 - Slag-forming mix - Google Patents

Description

The invention relates to steelmaking, in particular to slag-forming mixtures, used for casting steel. There are various ways to increase the quality of metal when casting steel from above. A special place among them is casting under the slag. In this case, exothermic mixtures are usually used, which are introduced directly into the mold. Exothermic mixtures are used, which are used for casting steel with powders, containing oxidizing agents, combustible and inert slag-forming components (fillers) 1. However, these mixtures used for casting steel through a layer of slag in molds and used casting modes in most cases do not provide a sufficient rate of formation of the liquid slag phase in the initial stage of filling the mold, which leads to a deterioration in the quality of the surface of the ingot and the added contamination of the metal with non-metallic inclusions. With an increase in the rate of filling, heat transfer between the metal and the mixture is intensified, the melting of the varnish mixture is accelerated. However, obtaining high quality metal during high-speed casting of steel has become impossible with the use of known exothermic slag-forming mixtures. At present, the task is to create compositions of slag-forming mixtures applicable for high-speed casting of steel. Closest to the invention in its technical essence and the effect achieved is an exothermic slag-forming mixture, including blast furnace slag, as well as aluminum, manganese ore, silicate lump, bauxite and lime in the following ratio of components, wt. Aluminum 4-8 Manganese ore9-12 Silicate block6-12 Slag of blast furnaces 10-40 Voksite 5-10 Lime Rest This mixture contains a smaller amount of combustible components (4 8 weight parts) and oxidizers (9-12 weight parts) ,

what is described above and therefore suitable for steel casting at a speed of 0.02-0.027 m / s (45-65 kg / s) The quality of the metal obtained during such a casting is due to the fact that the exothermic reaction: slag formation proceeds less rapidly, the viscosity of the resulting the slag is closer to the optimum and the thickness of the slag skull increases.

However, this mixture is unsuitable for more rapid casting of steel (for example, with a speed of 0.028 0, 038 M / ci (66-100 kg / s), since it still contains a certain amount of combustible components and oxidizers in combination with low-melting components. The use of such a mixture during faster casting (casting speed of 0.028-0.038 m / s (66,100 kg / s) leads to a rapid exothermic slag formation reaction, which is accompanied by splashes of metal, which contribute to the formation of slag-metal captivity on the surface of the slag, and the quality uchaemogo metal sharply reduced, to the formation of slag legkoplavkoro low viscosity, and therefore the formation of slag scull insufficient thickness,

which leads to the appearance of hot cracks and cracks hanging on the ingot,

As a result of this casting process, a low grade metal is obtained. A significant amount of combustible components and oxidizing agents makes the mixture more expensive and difficult to prepare. This composition is an exothermic slag-forming mixture of r.1 one component. and this worsens the slagging process.

The aim of the invention is to improve the quality of the metal by reducing rejects for hot cracks and slag-metal traces on the surface of the ingots, preventing the preparation of the slag-forming mixture and reducing its cost.

To achieve the goal, the slag-forming mixture, including blast furnace slag, additionally contains loams and dolomite in the following ratio of ingredients, wt.%: Loams 30-35

Dolomite 15-20

Slag Domain

furnacesEverything else

The loams are prion aluminosilicate material (Dnepropetrovsk deposit), having the following composition, wt.%:

63.77- 8.44- 3.31- 0.75- 5.65- 1.42- 0.057686, 2 9.40 4.10 0.89 7.4 1/97 0.073

Dolomite is a natural miner. (Yamskoye field, 3.36 1, 40.54 29.55. Light gray

The mixture according to the invention does not contain hot components and oxidizing agents, it is nonexothermal, contains a composition of 2 relatively low-melting components (loams and blast furnace slag) and one more refractory component, dolomite.

During high-speed casting (casting speed 0,028-0 ,, 038 m / s

Donetsk region of the following composition, wt.%:

the composition of 2 relatively low-melting fractions forms in a short period of time a liquid slag phase with a low melting point, which, with vigorous stirring, contributes to the dissolution of dlomite in this phase and to obtain the final slag with an optimum viscosity for

65 data casting conditions. The resulting 1.7-0.75-1.32- 3.86-10502, 0 0.84 1.5 5.2 1100 19.76 0.70 1.50 1460-1550

The lacquer contributes to the formation of a skull of a satisfactory thickness (1-1.5 mm), which leads to a decrease in the likelihood of hot cracks and cracks hanging on the surface of the ingot and contributes to improving the surface quality of the ingot.

Since there are no combustible components and oxidizing agents in the mixture, at high casting speeds, the possibility of exothermic reactions and the likelihood of slag metal capturing on the ingot surface are excluded - the quality of the metal is higher.

The composition of the slag-forming mixture according to the invention makes it possible to improve slag formation by reducing the number of components in the mixture. The mixture contains expensive components, it is economical and easy to manufacture, toxic and explosion-proof.

Best slagging conditions are observed when using the proposed mixture with the following ratios of the components included in it, wt.%:

Loams 30-35: Domain slag

ovens45-55

Dolomite 15-20

When high-speed casting of steel using a mixture of the specified composition, you can get high quality metal.

The introduction of these components in an amount less than the claimed lower limit leads to a significant decrease in the viscosity of the slag produced. The slag becomes low-melting and forms an insufficient thickness of the skull, which, in turn, contributes to the appearance of hot cracks and cracks on the surface.

ten

Dolomite

The study of the compositions of slag-forming mixtures showed that the surface of the ingots, cast with the use of mixtures 1 and 5, struck by captives. In this case, the metal contains an inclusion, i.e. the quality of the metal produced decreases.

The introduction of a mixture of loam, blast furnace slag and dolomite in an amount greater than the claimed upper limit results in a high-viscosity refractory slag, thereby reducing the slag formation process, the liquid phase in the slag becomes insignificant, the quality of slag deteriorates skull, and hence the possibility of the appearance of hot cracks and cracks hanging on the surface of the ingot, contamination of the metal with slag inclusions — the quality of the metal sharply decreases.

For the manufacture of the mixture, blast-furnace granulated coke-smelting pitch according to GOST 3476-60 with a sulfur content of not more than 2%, sug0 links of the Dneprodzerzhinsky deposit and dolomite of the Yamskoye deposit are used. When preparing the mixture, the components must be dried, blast furnace slag and dolomite from Velchen to the fraction

5 0.0005 m and then thoroughly mixed.

The sequence of mixing the components together is not regulated.

0

The proposed mixture can be applied in the form of granules and in the form of a powder, the flow rate of the mixture is 0.005-0.008 kg / kg steel. Under the proposed. The composition of the mixture can be poured into mass production sta bles with a carbon content of 0.1–0.70%.

Casting steel into ingots weighing 4.36 and 8 tons using the prepared mixture is carried out at a speed of 80 kg / s

0 through a glass hole of 50 mm from 250 ton buckets. The invention is illustrated with slag-forming compositions. mixtures that are listed in the table.

17.5

20

thirty

Slag mixture.

Claims (2)

When casting with the use of mixtures, no foam is observed on the surface of the ingots, the contamination of the metal does not increase, the yield of the suitable metal increases by more than 2%. Investigation of the ingot surface quality was carried out visually by. The study of the macrostructure and the content of non-metallic inclusions in the metal was carried out by sampling samples from the head, middle and bottom parts of the ingot roll. The content of non-metallic inclusions was also investigated by the cross-section of selected samples in the direction from the surface to the center of the sample. Studies have shown that the quality of the macrostructure of the metal and the content of non-metallic inclusions of the investigated steel grades correspond to the state standards specified for certain steel grades. . The implementation of the slag-forming mixture according to the invention, in the case of high-speed casting of steel in comparison with the prototype, makes it possible to improve the process of slag formation and to obtain a high-quality metal. The proposed blend as compared to the prototype has a low component, it is economical — it consists of low-cost components and its manufacture does not present any difficulties, the mixture in the manufacture is non-toxic and explosion-proof. When using the proposed composition of the expected economic effect of 118.8 rubles. per 1 ton of mixture. Slag-Forming Mixture, Including Blast Furnace Slag, is so that, in order to improve the quality of the metal by reducing scrap on hot cracks and slag-metal traces on the surface of the ingots, simplifying the preparation of slag mixture and reducing its cost price, it additionally contains loam and dolomite at the following ratio of ingredients, wt.%: Loams 30-35 Dolomite 15-20 Blast furnace slag The Other Sources of information taken into account during the examination 1. Author's witness Soviet Union № 544507, cl. B 22 O 27/04, 1975. 2. USSR author's certificate number 428853, cl. B 22 D 27/06, 1972.