CS240334B1 - Powder powders for continuous steel casters - Google Patents

Abstract

The invention solves the improvement of the desired properties of the casting powder, in particular its ability to absorb inclusions based on alumina, improving lubricating properties, increasing the surface and subsurface quality of slabs or billets while using a wider and more accessible raw material base. The casting powder for the above purpose according to the invention contains in mass terms 4 to 20% of sodium and/or potassium carbonate, 4 to 20% of fluorspar, sodium fluoride and cryolite individually or in their mutual combination, 2 to 15% of powdered graphite, carbon black and ground coke individually or in their mutual combination and 45 to 90% of a slag-forming component, formed by blast furnace slag, coal fly ash, manganese-silicate welding flux and flotation waste from graphite production individually or in their mutual combination. The essence of the invention lies in the fact that the casting powder contains slag-forming oxides, namely calcium oxide, silicon dioxide, aluminum oxide and manganese oxide in a molar ratio of 1: 1.0 to 2.3; 0.04 to 0.6: 0.01 to 0.3 parts in the resulting mixture.

Description

240334

BACKGROUND OF THE INVENTION The present invention relates to a casting powder c1 of a continuous steel casting mold, in particular by providing a deep-sealed deep-drawing and structural casting and improving the properties of the casting powder, particularly its ability to absorb alumina-based compositions, , lubricating properties, increasing surface and subsurface quality by the blades or billets using a wider and more affordable raw material base.

Powder casting powder, which is intended to form a lubricating film between a layer of solidified steel and a wall-crystallizer, provides a constant and uniform heat transfer between the solidified steel layer and the crystallizer, absorbing non-metallic inclusions, mainly oxidic inclusions, onto the liquid steel level. , to protect the surface of the liquid steel against oxidation oxygen and to provide it with thermal insulation. Most of the known dusting powders are mixtures consisting of slag-forming substances, viscosity-reducing substances, and the melting point of the powder and of the melt-speed control of the powder. As a tart-forming ingredients, Portland or Blast Furnace Cement, ashes from coal, limestone, lime, quartz sand, basalt, glass, nepheline and others are used. To reduce the viscosity and melting temperature, fluorspar, cryo-lithium, sodium fluoride, sodium carbonate, carbonate potassium, borax, and the like are added. Ground coke, carbon black, graphite powder and others are used as the melt speed regulator. The slag formed by the melting of the casting powder upon contact with the liquid steel level penetrates between the steel layer and the crystallizer wall, acting as a lubricant reducing the frictional forces of the crystallizer walls. In this case, if the heat transfer is too low, the layer-hardened steel formed is very thin and can break the steel, while the excessively high heat dissipation rate can cause surface defects in the blades. Therefore, the property of the powder, especially its viscosity, melting temperature, and metal absorption capacity, must be adapted to the particular type of steel casting and to the characteristics of the equipment used. All currently used casting powders have a biasity expressed as a calcium oxide / silica ratio close to 1. The melt of the casting powder to crystallize, resulting in a deterioration of the lubricating capacity, decreases with decreasing calcium oxide to silica ratio. , and with decreasing viscosity. A further disadvantage of the known powders is that they use hygroscopic components, such as ground, portland or blast furnace, to prepare them, which may cause powder to clump. For casting aluminum-soaked, especially deep-drawing and structural steels, casting powders having low viscosity, a high degree of alumina uptake and a low crystallization temperature are suitable, thereby preventing surface or surface defects of gates or bulges and other manufacturing difficulties. .

These drawbacks are overcome by the problem of casting powder for the purpose of the present invention, comprising from 4 to 20% by weight of sodium carbonate or potassium carbonate, from 4 to 20% of fluorspar, fluoride and cryolite by weight, or in combination with each other, from 2 to 15% by weight. % of graphite, carbon black and ground coke in combination with each other and 45 to 90% of a blasting component, consisting of blast furnace slag, coal fly ash, manganese silicon welding flux, graphite flotation waste, or in combination with each other. The manganosilicate welding flux contains 35 to 45% silicon dioxide, 35 to 40% manganese oxide and, as further components, titanate, calcium oxide, alumina and calcium fluoride. The present invention is based on the fact that the casting powder contains the wax-forming oxides, namely calcium oxide, silicon dioxide, aluminum manganese oxide in a molar ratio of 1: 1.0 to 2.3: 0.04 to 0.6: 0.01 to 0.3. parts in the resulting mixture. The resulting mixture has a moisture content of less than 1% and a fraction content above 0.1 mm should be below 10% by weight. The advantages of the casting powder of the invention, in particular, are that it has the ability to absorb an increased amount of oxide-aluminum inclusions, lower viscosity, less tendency to crystallize during melt cooling, thereby maintaining the presence of liquid slag on as large a surface as possible in the crystallizer and to the lowest surface temperatures at the exit of the crystallizer. This ensures an optimum level of inhalation removal, lubrication, heat transfer, while achieving good surface and subsurface quality or billets while substantially reducing manufacturing difficulties. The powder according to the invention does not contain hygroscopic ingredients which increase the susceptibility of the powder to clumping and, in addition to the alkali metal carbonates, contain other components which would release the gaseous products and cause the bulk powder to change in the crystallizer. A further advantage is that the powder is predominantly made up of waste products such as blast furnace slag, manganese silicon welding flux, coal fly ash, thereby extending the raw material base to its production and eliminating the need for energy-intensive products such as cement or lime. The increased manganese oxide content significantly reduces the interphase tension, thereby further improving the ability to assimilate. EXAMPLES: EXAMPLE

The casting powder is prepared by mixing 10

Vg! ~ 240334 wash. wt. % sodium carbonate, 12% w / w fluorspar, 3% w / w; powder graphite, 10 wt. 15% by weight of manganese carbonate flux; Coal and 50% wt. ground high-slag debris. The molar ratio of calcium oxide to silica, alumina and manganese oxide in the resulting mixture is 1: 1.46: 0.16: 0.14 die. The weight composition of the casting powder is silicon dioxide 31.6%, calcium oxide 20.2%, alumina 5.7%, magnesium oxide 4.4pre, manganese oxide 3.6%, sodium oxide 5.8%, calcium fluoride 10.5 %, elemental carbon 6%, moreover, components up to 100%. Melting point is at 1120 ° C, melting time 50 ° C. The viscosity at 1500 ° C is 0.13 Pa. Example 2

The casting powder is prepared by mixing 10pre. wt. sodium carbonate, 12 wt. Fluxed fluorspar, 6 wt. of powdered graphite, 22 wt. coal fly ash and 5 wt% ground blast furnace slag. The molar calcium hydroxide to silica, aluminum oxide and manganese oxide of the resulting mixture is equal to 1: 1.67: 0.26: 0.01 parts. Mass composition of casting powder: silica 33.0 ° / o, calcium oxide 18.5%, alumina 8.8 ° / o, magnesium oxide 7.1%, manganese oxide 0.3%, o: sodium oxide6.0% , calcium fluoride 10.1%, elemental carbon 6.5% and, moreover, components up to 100%. Melting point is at 1140 ° C, melting interval is 50 ° C. Viscosity at 1500 ° C is 0.27 Pa. Example 3

The casting powder is prepared by mixing 8 wt. sodium carbonate, 12 wt. Finished fluorspar, 6% wt. of graphite powder, 40 wt. of flotation waste from graphite production and 34% wt. ground blast furnace slag. The molar ratio of calcium oxide to silicon oxide, alumina and oxidumanganate in the resulting mixture is equal to 1: 1.99: 0.18: 0.01 parts. The weight composition of the casting powder is: silica 37.6., Calcium oxide 17.6%, alumina 5.6., Magnesium oxide 5.5%, manganese oxide 0.3%, sodium oxide 4.5. %, Calcium fluoride 10.1%, elemental carbon 7.3% and other components up to 100%. The melting start is 1100 ° C, the melting interval is 60 ° C. The viscosity at 1500 ° C is 0.26 Pa. s

The casting powder is prepared by mixing 10pre. wt. sodium carbonate, 15 wt. Flammable fluorspar, 7% wt. of powdered graphite and 68 wt. ground blast furnace slag. The molar ratio of calcium oxide to silica, alumina and oxidumanganate in the resulting mixture is equal to 1: 1.02: 0.07: 0.01 parts. The weight composition of the casting powder is: silica 29.8p., Calcium oxide 27.2%, alumina 3.4p., Magnesium oxide 5.8%, manganese oxide 0.3%, sodium oxide 5.8. %, calcium fluoride 12.8%, elemental carbon 7% and other components up to 100%. Melting point is 1 070 ° C, melting point 80 ° C. Viscosity at 1500 ° C is 0.035 Pa. Example 5

The casting powder is prepared by mixing 8pre. wt. sodium carbonate, 10 wt. Flammable fluorspar, 8% wt. powdered graffiti, 10 wt. of ground manganese silicon welding flux and 64 wt. mletejvysokopecnej slag. The molar ratio of calcium oxide to silica, aluminum oxide and manganese oxide in the resulting mixture is 1: 1.17: 0.06: 0.11 parts. The weight of the casting powder is: 31.3% silica, calcium oxide 24.9%, alumina 2.8%, magnesium oxide 7.5%, manganese oxide 3.6%, sodium oxide 4.7%, calcium fluoride 8.8%, elemental carbon 8% and, moreover, ingredients up to 100%. The start of melting is at 1060 ° C, the melting interval is 100 ° C. The viscosity at 1500 ° C is 0.07Pa. p

The casting powder is prepared by mixing 10pre. wt. sodium carbonate, 12 wt. Flammable fluorspar, 8% wt. of powdered graffiti, 50 wt. ground blast furnace slag, 10% wt. of ground manganese silicon welding flux and 10 wt. flotation waste from graphite production. The molar ratio of calcium oxide to silica, aluminum oxide and manganese oxide in the resulting mixture is 1: 1.42: 0.09: 0.14 parts. Mass composition of casting powder: silica 31.5%, calcium oxide 20.8%, alumina 3.3%, magnesium oxide 6.2%, manganese oxide 3.6%, sodium oxide 5.9%, calcium fluoride 10 5% elemental carbon 8.3% and, moreover, components up to 100%. The melting point is at 1025 ° C, the melting range is 75 ° C. The viscosity at ISOO ^C is 0.06Pa. with.

The invention can be utilized by manufacturing in rolling mills dealing with the extraction and processing of non-metallurgical raw materials, but also in steel mills where continuous casting or billet casting equipment is used, in particular aluminum deep-drawn and structural casting. .

Claims (1)

Casting powder for continuous steel casting crystallizers, in particular for casting deep-drawn and structural aluminum steels, containing by weight 4 to 20% of sodium and / or potassium carbonate, 4 to 20% of fluorspar, sodium fluoride and cryolite, individually or in combination , 2 to 15% of graphite powder, carbon black and ground coke, individually or in combination with each other, and 45 to 90% of the slag constituent, consisting of blast furnace slag, coal fly ash, manganese silicon welding flux and flotation waste from graphite production, a combination thereof, characterized in that the casting powder comprises slag-forming oxides, namely calcium oxide, silica, alumina and manganese oxide in a molar ratio of 1: 1.0 to 2.3: 0.04 to 0.6: 0 0.01 to 0.3 parts in the resulting mixture.