RU2746198C1 - Alumina mixture for liquefaction of metallurgical slag - Google Patents

Abstract

FIELD: chemistry.

SUBSTANCE: invention relates to a mixture of aluminium oxide for liquefaction of metallurgical slag during production of steel and alloys. Mixture consists of metal cranberry component and slag component, at that, metal crust component contains not less than 20.0 wt. % of aluminium crustal fraction +10 mm, not more than 4.0 wt. % of magnesium, not more than 3.0 wt. % of iron, not more than 3.0 wt. % of silicon, not more than 1.0 wt. % of copper and not more than 1.5 wt. % of zinc, and slag component contains not more than 18.0 wt. % of chlorine ions, not more than 25.0 wt. % of sodium and potassium salts in ratio 1:1, not more than 6.0 wt. % of calcium oxide, not more than 3.5 wt. % of magnesium oxide, not more than 9.0 wt. % of silicon oxide, not more than 3.0 wt. % of iron oxide Fe₂O₃, aluminium oxide is the rest. Mixture has hygroscopic moisture content of not more than 2 wt. % and content of magnetic fraction of not more than 4.0 wt. %.

EFFECT: use of the disclosed alumina mixture as an improved alumina-containing thinner of metallurgical slag in the production of steel and alloys, increases efficiency of the liquefaction process by reducing consumption of graphitized electrodes of complex steel processing facility, reduced consumption of electric energy, increased stability of lining of ladle and reduced specific consumption of refractories of slag belt, and also reduced consumption of lime used for slag liquefaction.

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Description

Technology area

The invention relates to the field of metallurgy, in particular, to the processing of secondary aluminum raw materials, and can be used at ferrous metallurgy enterprises as an alumina-containing liquefier of metallurgical slags in the production of steel and alloys.

The invention also relates to the field of production of building materials, in particular, to the processing of secondary aluminum raw materials, and can be used at enterprises producing insulation materials, as one of the components of the charge in the production of insulation materials.

State of the art

One of the main tasks of any metallurgical production is to ensure its environmental safety, both for its own employees and for the environment. One of the main problems for enterprises of the secondary aluminum industry is the problem of processing secondary aluminum raw materials containing chloride and fluoride salts of alkali and alkaline earth metals. In this regard, the task of complete or partial processing and sale of such secondary aluminum raw materials is urgent.

One of the solutions to the problem is the implementation of the leaching process - the dissolution of water-soluble salts in water, followed by drying of the solid residue, as well as evaporation of moisture from the remaining salt solution with the precipitation of the above salts into a solid precipitate. The disadvantage of implementing this process is the high cost of equipment, the energy consumption of the process, as well as high requirements for its environmental support.

A known method of obtaining a granular slag-forming mixture, including grinding and mixing ingredients, preparing an aqueous suspension, granulating and heat treatment (RU 2100131, B22D 11/00, published on 27.12.1997). The disadvantage of this method is the use of water in the production of a granular mixture, the presence of which limits the use of alumina-containing materials, which include chlorides of alkali and alkaline earth metals.

Known mixture for processing molten steel in a ladle containing lime, alumina and fluorine material and aluminum. Alumina-containing slag of ferroalloy production (RU 2039091, С21С 7/064, published on 09.07.1995) is used as alumina-containing and fluorine-containing material. The disadvantages of the known mixture are the high price due to the use in the composition of a significant amount of pure aluminum, low refining ability in relation to the removal of non-metallic inclusions.

Known slag-forming mixture for protecting the surface of steel in the tundish MNRL, which includes 36-40% of microsilica, 19-23% of dusty waste from aluminum production and 39-43% of dusty waste from lime production (RU 2356687, С21С 5/54, published 27.05 .2009). The disadvantages of the known material are: high emissions of dusty waste from aluminum production, the presence of fluorine in the chemical composition of the mixture.

Known exothermic mixture for deoxidation, refining, modification and alloying of steel, containing: aluminum - 5.0-83%, aluminum oxide - 2.5-75%, calcium oxide - 0.5-10%, magnesium oxide - no more than 8 %, iron oxide no more than 15%, copper oxide - no more than 2%, titanium oxide - no more than 7%, manganese oxide - no more than 12%, Na and / or K oxides - 5-7% (RU 2252265, class С21С 7/00, C21C 7/06, published 20.05.2005). The disadvantages of the known material are the instability of the resulting chemical composition, which in turn reduces the quality of steel obtained by smelting using a known mixture, the high cost of the material in versions using primary aluminum slags to create an exothermic mixture.

Known flux for deoxidation, refining, modification and alloying of steel, containing: aluminum - 1.0-60%, aluminum oxide - 1.0-50%, calcium oxide - 0.28-1.0%, magnesium oxide - 1, 0-10.0%, iron oxide 1.0-9.0%, silicon dioxide - 1.0-16.0%, copper oxide - 1.0-10.0%, zinc oxide - 0.2-12 , 0%, manganese oxide - 0.1-2.0%, lead oxide - 0.01-0.5%, nickel oxide - 0.01-0.15%, chromium oxide - 0.05-0.5 %, sodium chlorides - 0.1-40.0% and potassium chlorides - 0.1-40.0%. The flux can be used in lumpy form with a fraction of 10-500 mm or in the form of a briquette with dimensions of 10-120 mm, obtained by pressing or sintering slag screenings with a fraction of -2 mm (RU 2396364, C22B 9/10, C21C 7/06, publication 10.08. 2010). The disadvantages of the known material are the instability of the chemical and fractional compositions, the high cost of the material, the high cost of the material in versions using primary aluminum slags to create a flux.

There is a known method for processing slag of aluminum production to obtain alumina-containing raw materials, which consists in crushing the slag, separating it into fractions, water leaching of crushed slag, filtering the solution with the separation of saline solution and solid residue, evaporating saline solution, drying and roasting the solid residue (RU 2215048, C22B 7/04, published 27.10.2003). The resulting alumina-containing material also contains aluminum, oxides of silicon, iron, magnesium, sodium and potassium chlorides. The disadvantages of this method are the high energy intensity of the technology used due to the operations of leaching, drying and roasting of the solid residue, evaporation of the salt solution, as well as the long duration of the technological process and the low percentage of the yield of the suitable product. In addition to alumina, the resulting raw material contains a significant amount of metal oxides, which greatly complicates its effective use as a flux for deoxidation and slagging in steelmaking.

Known exothermic mixture for deoxidation, refining, modification and alloying of steel (RU 2252265 C1, class C21C 7/06, published 20.05.2005). The known mixture contains aluminum, aluminum oxides, oxides of calcium, magnesium, iron, copper, titanium, manganese and sodium and / or potassium. The ratio of the components in the known briquette is as follows, wt. %: aluminum 5.0-83, aluminum oxide 2.5-75, calcium oxide 0.5-10, magnesium oxide no more than 8, iron oxide no more than 15, copper oxide no more than 2, titanium oxide no more than 7, oxide manganese not more than 12, sodium and / or potassium oxides 5-7. The disadvantage of the known mixture should be considered the laboriousness and high cost of manufacturing, additional costs for fusion.

The problem to be solved by the invention is the development of a cheap, waste-free and effective method for processing secondary aluminum raw materials (waste) with obtaining an alumina mixture of a certain chemical composition for use as an alumina-containing liquefier of metallurgical slags in the production of steel and alloys.

Disclosure of invention

The technical result of the invention is the development of the composition of an alumina mixture, which is used as an improved alumina-containing liquefier of metallurgical slags in the production of steel and alloys, which makes it possible to increase the efficiency of the liquefaction process during steel smelting by improving a number of process parameters, such as reducing the consumption of graphite electrodes AKOS, reducing consumption e / e, an increase in the durability of the ladle lining and a decrease in the specific consumption of refractories of the slag belt, a decrease in the consumption of lime used to liquefy the slag.

The technical result is achieved by the fact that an alumina mixture is proposed for liquefying metallurgical slags in the production of steel and alloys, consisting of a metal (bead) component (1) and a slag component (2), with the following content of the following components and elements:

1) metal (barb) component, wt. %:

- metal bead aluminum of fraction +10 mm not less than 20.0

- magnesium not more than 4.0

- iron not more than 3.0

- silicon no more than 3.0

- copper no more than 1.0

- zinc not more than 1.5,

2) slag component, wt. %:

- chlorine ions no more than 18.0

- sodium and potassium salts in a ratio of 1: 1 to 25.0

- calcium oxide not more than 6.0

- magnesium oxide no more than 3.5

- silicon oxide no more than 9.0

- iron oxide (Fe ₂ O ₃ ) no more than 3.0,

the mixture has a hygroscopic moisture content of not more than 2 wt. % and the content of the magnetic fraction is not more than 4.0 wt. %, and also characterized by the absence of pieces of "flushing" slag.

Provided that consumers are satisfied with the chemical composition of the proposed material, special attention is paid to the moisture content during production. So, the average permissible moisture contamination is no more than 2 wt. %. Alumina-containing materials are hygroscopic and usually lie in bulk in unheated warehouses or open areas for a long time before being shipped to consumers. Thus, the manufacturing process from the moment the material is formed to the moment it is packed in a moisture-proof container should be minimized.

It is also desirable that the alumina mixture has no mechanical clogging with ferrous metal scrap, which is constantly present in the original material, the minimum concentration of sulfur and the absence of fluorspar in the composition, which easily passes into the gaseous phase and forms hazardous volatile compounds with Al and Mg.

Sodium and potassium salts contained in the mixture of alumina flux, which form eutectics during the smelting process, reduce the reaction temperature in the ladle furnace, accelerate the process of liquefaction of the slag in the ladle furnace, removing the sulfur contained in the steel into the slag, simultaneously improve the reactivity of the mixture, promote uniform distribution of slag on the metal mirror in AKOS due to liquid mobility at high temperatures. In parallel, they protect the slag belt - the lining of the ladle, by creating a fluidized bed between the liquid steel and refractories (periclase).

According to the content of metallic aluminum: there is a process of active oxidation of aluminum with a transfer to the oxide phase and the release of iron oxide. Thus, the slag foams, improving the shielding of arcs from the AKOS electrodes.

The aluminum oxide present in the mixture helps to reduce the consumption of CaO (lime) during the slag liquefaction procedure. Converts the acidity of the slag to more basic compounds.

The quantitative content of the components of the mixture was determined experimentally and is optimal from the point of view of the beneficial effect. Going beyond the specified limits of the content of elements negatively affects the properties of the mixture and its effectiveness when used as a thinner.

The alumina mixture is a by-product of processing (crushing, classification) of aluminum slag - waste of secondary remelting of aluminum scrap, dross, as well as aluminum slag, rich in aluminum metal using rotary tilting furnaces.

The initial raw material for the manufacture of the alumina mixture is high-temperature salt dump slags formed immediately after remelting the aluminum-containing raw material in rotary tilting furnaces. It is not allowed to use as a raw material the slags formed during the "washing" of the furnaces with fluxes.

The technological process of processing raw materials for a mixture of alumina in general form contains the following stages: melting the starting material in a rotary furnace, cooling the material with subsequent crushing, magnetizing the magnetic fraction containing iron, magnetizing the non-magnetic metal fraction on vortex magnets, classification of the material with sampling and analysis in the laboratory , supply for packaging or pressing of material with enrichment according to the required parameters.

As a result of using this method, a material is obtained with a given fractional composition, purified from the mechanical magnetic fraction and with a stable chemical composition, while the moisture content of the material is no more than 2 wt. %.

The alumina mixture can be supplied in the form of two fractions:

- fraction 50-150 mm;

- fraction 0-50 mm.

Delivery of other fractions is also possible as agreed with the consumer. The lower and upper boundaries of the particle size distribution are determined by the method of feeding the material and the rate of melting in relation to each process.

Implementation of the invention

Industrial tests of this alumina mixture have shown that it can be used with great efficiency as an alumina-containing diluent of metallurgical slags in the production of steel and alloys. The given qualitative and quantitative composition of the alumina mixture is optimal from the point of view of the greatest efficiency and usefulness. This conclusion is dictated by the conducted laboratory and industrial research.

It was experimentally found that the use of the claimed alumina mixture allows, in similar processes, differing only in the used thinners, to reduce the consumption of graphite electrodes AKOS and the consumption of electricity, increase the durability of the ladle lining and reduce the specific consumption of refractories in the slag belt, and reduce the consumption of lime used to liquefy the slag. , which accordingly provides a reduction in the cost of the process of obtaining steel and alloys.

To compare the results obtained, standard breakers disclosed in the prior art were used.

The use of this invention also makes it possible to transfer all alumina-containing products of processing of secondary aluminum raw materials from waste of IV hazard class, requiring placement at a specialized landfill, into a finished material - an alumina-containing thinner of metallurgical slags.

The resulting alumina mixture is used in steel production technology at real operating enterprises and has proven its effectiveness. Based on the data obtained, technical specifications were developed, which were approved and are being successfully applied at the moment at the enterprise.

Claims (8)

1. An alumina mixture for liquefying metallurgical slags in the production of steel and alloys, consisting of a metal bead component (1) and a slag component (2), with the following content of components in them: 1) metal bar component, wt%: aluminum metal bead fraction +10 mm not less than 20.0 magnesium no more than 4.0 iron no more than 3.0 silicon no more than 3.0 copper no more than 1.0 zinc no more than 1.5 2) slag component, wt%: chlorine ions no more than 18.0 sodium and potassium salts in a 1: 1 ratio no more than 25.0 calcium oxide not more than 6.0 magnesium oxide no more than 3.5 silicon oxide no more than 9.0 iron oxide Fe ₂ O ₃ no more than 3.0 aluminium oxide rest, the mixture has a hygroscopic moisture content of not more than 2 wt% and a magnetic fraction content of not more than 4.0 wt%. 2. A mixture according to claim 1, characterized in that it is in the form of a fraction of 50-150 mm. 3. A mixture according to claim 1, characterized in that it is in the form of a fraction of up to 50 mm.