RU2374327C2 - Steel-smelting flux and method of its producing (versions) - Google Patents

Abstract

FIELD: metallurgy.

SUBSTANCE: invention relates to ferrous metallurgy field, particularly it concerns to manufacturing of flux used at manufacturing of steel in converters. Steel-smelting flux containing magnesium oxide, calcium oxide, ferric oxide, silicon oxide, aluminium oxide, organic and/or mineral compounds and carbon, additionally contains oxides and/or chlorides, and/or fluorides of alkaline metals and hydrocarbonate forms of magnesium, defined in the from of losses at ignition. At receiving of steel-smelting flux there are mixed burnt in rotary kiln magnesia-bearing and binding materials, there are briquettes received mass with additional introduction into content of charge aluminium-bearing wastes from aluminium manufacturing and also carbon-bearing materials or natural magnesite and/or nemalite.

EFFECT: invention provides receiving of flux with low accessible porosity and high durability at compression and also increasing of yield.

3 cl, 2 tbl, 1 ex

Description

The invention relates to the field of ferrous metallurgy, in particular to compositions and methods for the production of fluxes used in the manufacture of steel in converters.

Known flux ironized magnesia (POF), containing 80-90% of magnesium oxides; 1.5-3% calcium oxides; 6-8% iron oxides and 1.5-3.5% silicon oxides used for steelmaking in converters. Flux is produced by co-firing in rotary kilns of magnesia materials and iron-containing additives [1].

The disadvantage of the composition of sintered POF is its slow dissolution in the slag melt due to the small amount of iron oxides present in it, which are insufficient for the binding of magnesium oxides to magnesioferrites, which are instantly soluble in ferruginous slag. As a result, periclase (MgO) refractory grains are formed in the flux, which impede the rapid dissolution of the flux in the slag. The latter circumstance limits the use of POF in the converter during the application of the slag skull on the converter lining.

Closest to the claimed invention, a composition of the same purpose, adopted as a prototype for the totality of essential features, is the composition of the flux of magnesia briquetted with carbon and iron oxides (FMBUZH), containing 1-35% calcium oxides, 3-15% iron oxides; 1-10% silicon oxides; 1-4% aluminum oxides; 1-10% of organic and (or) mineral compounds; 3-20% of carbon and the rest are magnesium oxides [2]. The flux is made by mixing the components of the mixture, followed by briquetting the resulting mass into finished briquettes. The composition of the charge components is as follows: calcined magnesite containing iron oxides (a fine fraction of POF), caustic magnesite, coke and ligaments in the form of lingosulfanate [3].

The disadvantage of properties depending both on the composition of the above flux and on the method of its production, in particular the composition of the charge components, is the high open porosity and low values of compressive strength, which leads to a decrease in the yield of suitable flux. These disadvantages are explained by the fact that during mixing of the charge components together with a binder in which moisture is present, as well as with further briquetting of the mixture, significant amounts of thermal energy are released, which contributes to the release of moisture vapor. Moisture vapor forms pores during cooling of finished briquettes, increasing the porosity of the finished briquettes, reducing their density of the briquettes and reducing the cohesion of the particles of the components, leading to a decrease in the compressive strength.

The objective of the invention is the creation of a flux having low open porosity, high compressive strength, and increase yield.

The problem is achieved in that the known briquetted flux containing oxides of magnesium, calcium, iron, silicon, aluminum, organic and (or) mineral compounds and carbon, according to the invention additionally contains oxides and (or) chlorides of alkali metals and hydrocarbonate forms of magnesium, defined in the form of losses during calcination in the following ratio of components, wt.%:

calcium oxide 0.5-10.0 iron oxide 0.1-8.0 aluminium oxide 0.1-15.0 silica 1.0-8.0 oxides and (or) chlorides alkali metals 0.01-5.0 ignition loss 0.1-30.0 carbon 0.01-12.0 organic and (or) mineral compounds 1.0-10.0 magnesium oxide rest.

The open porosity of the inventive flux is reduced by a method for producing flux, comprising mixing magnesia-containing, carbon-containing and binder materials burned in a rotary kiln, briquetting the resulting mass in the form of briquettes and, according to the invention, additional introduction of aluminum-containing waste from aluminum production in the following ratio of charge materials, wt.%%

calcined magnesia-containing materials 20-80 carbon materials 0.5-12 binding materials 1.0-6.0 aluminum-containing waste from aluminum production rest.

The increase in compressive strength, as well as increase the yield of the inventive flux, is facilitated by a method for producing flux, comprising mixing magnesia-containing and binder materials burned in a rotary kiln, briquetting the resulting mass in the form of briquettes and, according to the invention, the additional introduction of natural magnesite and (or) brucite, and also aluminum-containing waste from aluminum production in the following ratio of charge materials, wt.%:

calcined magnesia-containing materials 10-28 magnesite and (or) brucite 20-65 binding materials 1.0-6.0 aluminum waste from aluminum production Rest.

The presence in the steelmaking flux of oxides and (or) chlorides, and (or) fluorides of alkali metals (Na ₂ O, K ₂ O, NaCl, KCl, NaF, KF) is due to the introduction of aluminum slag into the mixture, which is a waste in the production of secondary aluminum from aluminum scrap. The content of oxides and chlorides in such slag can reach 30%.

When the mixture is mixed with a binder containing moisture, with further briquetting of the flux, the oxides and (or) chlorides and (or) alkali metal fluorides contained in it, dissolving in water, form an alkaline solution with increased density. The evaporation temperature of this solution is higher than the evaporation temperature of water. Therefore, when mixing and briquetting the flux, the released thermal energy is not enough for the formation of substances in the vapor state. An exception in the manufacture of a flux of vaporous substances reduces porosity and increases the adhesion between particles of the components of the mixture during briquetting of flux.

The introduction of the mixture, along with the aluminum slag of natural magnesite and (or) brucite, due to the presence of hydrocarbonate forms in them, as well as the increased content of aluminum oxides in the aluminum slag increase the astringent properties of magnesite and brucite. As a result, the adhesion force of the flux particles increases, which leads to an increase in the compressive strength of the flux and, thereby, to an increase in the yield of flux during its manufacture.

If the content in the flux of oxides and (or) chlorides, and (or) fluorides of alkali metals is less than 0.01%, then they will not affect the density of water, and the amount of water vapor will not change, as a result of which the flux porosity will be high. If the content of oxides and (or) chlorides, and (or) fluorides in the flux is higher than 30%, the environmental situation worsens during the preparation of the flux due to the release of these substances into the atmosphere. The flux content of oxides and (or) chlorides, and (or) fluorides depends on the introduction of the appropriate amount of aluminum-containing waste into the charge from the production of aluminum.

If magnesite and (or) brucite are introduced into the mixture in an amount of less than 20% and, accordingly, less than 0.1% loss on ignition is obtained in the flux, the flux will have low compressive strength due to a decrease in the binding properties of aluminum slag and hydrocarbonate forms when briquetting flux. If the amount of magnesite and (or) brucite in the composition of the charge is more than 65% and, accordingly, in the composition of the flux, the loss content during calcination is more than 30%, then it will have a strong cooling effect on hot steelmaking slag when it is used due to the absorption of thermal energy at dissociation of hydrocarbonate forms of magnesite or brucite.

The novelty of the composition of the inventive steelmaking flux and the method of its production (with an option) is due to the absence in the patents and literature of fluxes containing oxides of magnesium, calcium, iron, silicon, aluminum, carbon, organic and (or) mineral compounds, the presence of oxides and (or ) chlorides, and (or) alkali metal fluorides and losses during calcination, and the composition of the mixture to obtain such fluxes is the presence of aluminum-containing waste from aluminum production.

The introduction into the charge of aluminum-containing waste from aluminum production in the inventive method for producing steelmaking flux and the presence in the composition of the flux of oxides and (or) chlorides and (or) fluorides of alkali metals, which increase the density of water entering into the binder and, thereby, reduce vaporization, which leads to a decrease in the porosity of the flux, determines the non-obviousness of the claimed composition of the flux and the method of its production.

The method of preparation of steelmaking flux is as follows.

The required amount of calcined magnesia-containing material of a fraction of less than 4.0 mm, aluminum slag of a fraction of less than 6 mm and a coke fraction of less than 4.0 mm are loaded into the cube. From the plug, the mixture is loaded into a paddle mixer. The required amount of binder (organic or mineral compounds) diluted with water to a density of 1.0-1.5 kg / l is introduced into the mixer and the entire mixture is mixed for 20-30 minutes. Through the conveyor, the mixture is fed into a roller briquette press (ПБВ-700/200) with a pressing force of 200 tons without a prepress. The finished briquettes from the press are conveyed to the drying chamber via a conveyor belt, and then to the finished product bin.

Example 1 of a specific implementation of the method.

A mixture of materials in the amount of 300 kg was loaded into the cube. The amount and composition of the mixture are presented in table 1.

While mixing the mixture, a solution consisting of a binder and water with a density of 1.2 kg / l was introduced into the mixer. Lingosulfanate (mineral binder) or phenol-formaldehyde resin (organic binder) were used as binders. Lingosulfanate or sulphide-yeast mash (SDB) is obtained from sulphide liquor formed during sulphate pulping. Phenol formaldehyde resin is a product of the joint condensation of phenols, formaldehyde and furfulol. After mixing, the mixture entered the press, after which the briquettes were dried at a temperature of 200 ° C and shipped to the finished product hopper.

Table 2 shows the compositions and properties of the resulting steelmaking fluxes produced according to various options for their preparation. The table shows that the inventive steelmaking flux containing oxides and (or) chlorides, and (or) alkali metal fluorides has a 6.5-11% lower porosity, and when it contains bicarbonate forms of magnesium (loss on ignition) flux strength higher by 1.8-6.2 MPa in comparison with the composition of the known flux. Also significantly increased the yield of steelmaking flux in the form of briquettes with the claimed methods of its manufacture.

Information sources.

1. Demidov K.N., Lamukhin A.P., Shatilov O.F. and others. Steel smelting in converters using fluxes with a high content of magnesium oxides. G. New refractories, No. 5, 2005, p.13.

2. Patent of the Russian Federation No. 2299913, filed April 12, 2005.

3. The production of steel smelting flux of magnesia briquetted containing carbon and iron oxides (FMBUZH). Technological instruction TI 201-0-01-4, LLC “Bumperprocessing”.

table 2 The composition and properties of the known (prototype) and the inventive fluxes, depending on the variants of the claimed blending of mixtures to obtain fluxes. Name Flux fabrication (options) Famous Of the claimed one 2 3 four 5 6 The composition of the flux,% Calcium oxide 3,1 2.9 2.7 1,5 1.4 1.32 Iron oxide 5.8 6.7 6.1 3.04 2.5 2.9 Aluminium oxide 1.3 7.1 8.7 13.9 14.2 Silica 2.5 3.4 3,1 3.2 2.9 3.2 Alkali metal oxides, chlorides and fluorides - 0.91 1.3 2.2 2.14 2.1 Loss on ignition - 1.3 2.1 21.9 24.9 14.5 Carbon 7.75 7.6 7.83 0.11 0.1 0.1 Organic and (or) mineral compounds - 4.3 3.9 3,5 3.2 3.2 Magnesium oxide 79.55 65.79 64.27 50.65 48.66 58.38 Flux Properties: 16.8 10.3 7.4 5.8 6.3 6.1 Open porosity,% The limit of compressive strength, MPa 3.6 5,4 6.1 8.7 9.8 7.9 The yield of briquettes,% 72 84 85 87 89 86

Claims (3)

1. Steelmaking flux containing oxides of magnesium, calcium, iron, silicon, aluminum, organic and / or mineral compounds and carbon, characterized in that it additionally contains oxides and / or chlorides, and / or fluorides of alkali metals and hydrocarbonate forms of magnesium, defined in the form of losses during calcination in the following ratio of components, wt.%:
calcium oxide 0.5-10.0 iron oxide 0.1-8.0 aluminium oxide 0.1-15.0 silica 1.0-8.0 oxides and / or chlorides, and / or alkali metal fluorides 0.01-5.0 ignition loss 0.1-30.0 carbon 0.01-12.0 organic and / or mineral compounds 1.0-10.0 magnesium oxide rest 2. The method of producing steelmaking flux according to claim 1, comprising mixing the magnesia-containing, carbon-containing and binder materials burned in a rotary kiln, briquetting the resulting mass in the form of briquettes, characterized in that aluminum-containing wastes from aluminum production are additionally introduced into the charge composition in the following ratio of charge materials , wt.%:
calcined magnesia-containing materials 20.0-80.0 carbon materials 1.0-12.0 binding materials 1.0-6.0 aluminum-containing waste from aluminum production rest 3. The method for producing the steelmaking flux according to claim 1, comprising mixing the magnesia-containing and binder materials burned in a rotary kiln and briquetting the resulting mass in the form of briquettes, characterized in that natural magnesite and / or brucite, as well as aluminum-containing waste from aluminum production in the following ratio of charge materials, wt.%:
calcined magnesia-containing materials 10.0-28.0 magnesite and / or brucite 20.0-65.0 binding materials 1.0-6.0 aluminum-containing waste from aluminum production rest