SU1715872A1 - Method of preparing change for producing aluminium-silicium alloys by carbothermic reduction - Google Patents

Abstract

The invention relates to the metallurgy of non-ferrous metals and relates to a method for preparing a charge for producing electrothermal aluminum-silicon alloys by the carbothermic reduction of aluminum and silicon oxides to their elements in ore-reducing furnaces. The aim of the invention is to increase the recovery of aluminum and silicon from the charge into the alloy, to reduce the energy consumption for the production of aluminum-silicon alloys and to increase its aluminum content. What is new in the preparation of the blend is that the Method relates to the field of metallurgy of non-ferrous metals and concerns the method of preparation of the charge for producing electrically-thermal aluminum-silicon alloys-carbothermic reduction of aluminum and silicon oxides to their elements in ore-smelting furnaces. The technical and economic indicators of the process for producing aluminum-silicon alloys depend not only on the type and amount of raw materials used to obtain them, on the ratio between them in the charge, and directly carbon-containing reducing agent and alumina at a non-volatile carbon ratio to alumina 0.45 -1.06. Another difference is that lump silica / or granulated silica-alumina raw material is added to the mixture before sintering or after sintering, providing 90-155% non-volatile carbon in stoichiometric amount needed to reduce all oxides of the mixture to their metals. Thus, in the ore recovery furnace, the mixture consisting of a mixture of two compounds is melted: one component of the mixture contains a carbon-containing reducing agent and alumina and the other component of the mixture is either agglomerated with silica-alumina raw material, or lump silica, or their mixture. In addition, these two compositions of the mixture can be taken in separate pieces or co-agglomerated and be separate structural components in one piece of the charge. 3 tab. the volume of the pelletized charge. Therefore, one of the ways to improve the efficiency of smelting alloys is to create the most favorable conditions for the reduction processes by preparing the charge for smelting. Known methods for the preparation of the charge for the production of aluminum-silicon alloys, including the dosage of charge materials containing silica-alumina raw materials, for example, kaolin, high-alumina concentrate, distansillimanite concentrate, quarCO N N ...

Description

Purum sand, carbonaceous reducing agent - coal, petroleum coke and binder, their joint mixing, sintering of the charge and smelting of the agglomerated charge in the ore recovery furnace.

A known method of preparing briquetted charge for ore-smelting smelting consists in performing the following operations: crushing and grinding of the reducing agent and bonding clay, dosing of the charge components, mixing and running, pressing and drying the briquettes.

A method of producing aluminum-silicon alloys is known by restoring a briquetted mixture of raw materials with a carbonaceous reducing agent in an electric furnace / consisting in using briquettes made of alumina, silica sand and a high-melting fraction of coal extract, in which part of the alumina is replaced with kaolin.

A known method for producing aluminum-silicon intermediate alloys in an electrothermal furnace is characterized in that the reduced oxide and the reducing agent are loaded into an electrothermal furnace in a lumpy form and the kaolin alumina mixture in a lumpy form with quartz and a reducing agent in a lumpy form is loaded into an electric furnace.

A known method for producing aluminum-silicon alloys, including the preparation of charge materials, their dosing and mixing, briquetting the charge, drying the briquettes and melting them.

A disadvantage of the known methods for producing aluminum-silicon alloys is the slagging of a portion of the charge during the smelting reduction process and the associated loss of alloy.

The closest to the proposed method is the production of alumina-silicon alloys, characterized in that the mixture of silica-alumina raw material, before being mixed with charcoal-containing reducing agent, is pelletized to a particle size of 0.1-15 mm, i.e. carbon-based reducing agent and pelletized silica-alumina raw material are briquetted together.

A disadvantage of the known method of producing aluminum-silicon alloys is that it is not possible to produce alloys with a high aluminum content (60% and bdley) without significantly increasing the specific energy consumption for producing an alloy and reducing the extraction of aluminum and silicon from the charge into the alloy. .

The aim of the invention is to increase the extraction of aluminum and silicon from the charge into the alloy, reducing the energy consumption for the production of aluminum silicon

alloys and increasing its aluminum content.

The goal is achieved by mixing the mass of carbon-containing reducing agent and alumina with respect to

0 non-volatile carbon-based reducing agent for alumina 0.45-1.06 and then agglomerated silica-alumina is added to the mixture before sintering or after sintering.

5 raw materials and / or lump silica in an amount that provides the composition of the mixture with a nonvolatile carbon content of 90-115% of the stoichiometric amount necessary to reduce all oxides of the mixture to their metals.

Unlike the prototype, in an ore-reducing electric furnace, the mixture is melted consisting of a mixture of two compositions: one component of the mixture contains carbon-containing reducing agent and alumina and the other component is either agglomerated silica-alumina raw material, or lump silica, or their mixture. In addition, these two mixtures can be taken in separate pieces or jointly eaten and be separate structural components in one piece of the charge. At the same time to achieve the reduction of all oxides of the charge to their

5 metals, the content of non-volatile carbon in the charge is maintained equal to 90-115% of the stoichiometric amount required to reduce the oxides of the charge to their metals by introducing agglomerated silica-alumina raw materials and / or lump silica.

In the known method of producing aluminum-silicon alloys, silica-alumina raw materials containing

5 aluminosilicates, alumina, quartz sand and other components, thoroughly mixed, corroded and in lumpy form introduced into the carbon-containing reducing agent. Therefore, in the initial period, the processes of reducing aluminum and silicon oxides occur due to the diffusion of carbon into the bulk of the oxide raw material, forming primarily silicon carbide and aluminum oxycarbide, which, together with aluminum oxide and silicon, which have not been converted to carbon, produce low-melting systems leading to slagging. Despite the fact that, in the implementation of a known method, the processes of the onset of the reduction of aluminum oxides and silicon with carbon

proceeds at a higher temperature than in thoroughly mixed briquetted mixtures of oxide raw materials and a carbon-containing reductant; slag formation conditions remain in the ore recovery furnace due to the formation of low-melting systems in the oxide piece. The slagging of part of the charge leads to a decrease in the extraction of aluminum and silicon from the charge into the alloy, a decrease in the aluminum content in the melted alloy, and an increase in the energy costs for the production of the alloy.

In order to avoid loss of the alloy due to slag formation in the electric furnace and to increase the aluminum content in the alloyed alloy and reduce energy consumption, a method for preparing the charge for the production of electrothermal aluminum – silicon – silicon alloys has been proposed, which means that the mass of reduced carbon containing reducing agent containing the mixture is mixed with alumina with the ratio of non-volatile carbon-containing reducing agent to alumina 0.45-1.06 and then to the resulting mixture before sintering or after its lumps are additionally added with agglomerated silica-alumina raw materials and / or lump silica in an amount that provides the content of non-volatile carbon in the charge of 90-115% of the excess amount necessary for the reduction of all oxides of the charge to their metals.

By introducing into the mixture a separate component of a mixture of carbon-containing reducing agent and alumina in a ratio of 0.45-1.06, which ensures the reduction of alumina to aluminum carbide in the entire range of limiting values of this ratio, it is possible to change the reduction process chemistry in such a way that aluminum silicium The alloy in the final reduction stage is obtained by reacting mainly aluminum carbide and partially silicon carbide with silicon oxide or silicon oxides and aluminum.

Due to the fact that the alumina is reduced to aluminum carbide in the process of ore-smelting smelting and is separated from the silicon oxides and aluminum contained in the charge in the earthen form, it is possible to avoid the formation of fusible systems consisting of aluminum oxycarbide, silicon carbide and aluminum oxides and silicon, and ultimately reduce slagging in the electric furnace;

to increase the extraction of the alloy from the charge and reduce the energy consumption for the production of the alloy ...

In addition, thanks to the interaction

in the final stage of reduction of aluminum carbide with silicon oxide or silicon oxide and aluminum oxide contained in the calcined oxide raw material, it is possible to take aluminum silicon alloys with an aluminum content of 72% or more, while its content in alloys obtained by known methods does not reach more than 61%.

5 P p and me p. Powdered carbonaceous reducing agent coal gas and petroleum coke is taken in a 1: 1 ratio by weight, and technical alumina is metered at

In this, the ratio between the non-volatile carbon of the carbon-containing reductant and alumina is 0.45-1.06. Coal, petroleum coke and technical alumina, which can be used as

5 materials containing the basic alumina component are mixed and moistened with an aqueous binder solution, usually technical lignosulfonate. Then, agglomerated silica-alumina raw material, or lumpy silica, or lumpy silica and agglomerated silica, are additionally added to the mixture before sacking or after sintering.

5 raw materials.

Thus, agglomerated silica-alumina raw material and / or lump silica additionally added to the mixture of carbon-containing reducing agent and / or lump silica is either snapped together with the mixture and they are in the bulk of the piece as separate structural components or they are mixed after each piece separately.

five .

Since the mixture of carbon-containing reducing agent and alumina contains non-volatile carbon of at least stoichiometric amount required for reducing alumina to its carbide, an agglomerated silica-alumina raw material and / or lumpy silica are added to the mixture based on the reduction of aluminum carbide and add5 oxides to their metals, i.e. due to the addition to the mixture of carbon-containing reducing agent and alumina agglomerated oxides, in the total mass of the mixture, the content of nonvolatile carbon is equal to 90-115% of its stoichiometric mass, necessary for the reduction of all oxides of the mixture to their metals.

The limiting ratios between the non-volatile carbon of the carbon-containing reductant and alumina are selected from the condition of achieving the minimum slag formation in the electric furnace during the process of redressing smelting. This is achieved due to the fact that the most difficult-to-restore alumina is thoroughly mixed with the carbon-containing reducing agent and, being in the composition of the charge of a separate structural component, in the first reduction stage forms aluminum carbide by the reaction:

2А 20з + 9С А14Сз + 6СО (1)

The stoichiometric ratio between nonvolatile carbon and alumina, which ensures the reaction (1) is equal to 0.529. However, under industrial conditions, no chemically pure alumina is used. Usually, technical alumina with an alumina content of 93-97% and also alumina of fine fractions after low-temperature calcination of aluminum hydroxide containing up to 85% alumina (the rest is PPP and impurities) are introduced into the charge. Based on the composition of alumina used in the production of aluminum-silicon alloys (alumina content 85%), the stoichiometric ratio between the mass of nonvolatile carbon and the mass of alumina ensuring the reaction (1), i.e. the conversion of alumina to its carbide will be 0.45. This ratio of the mass of non-volatile carbon to the mass of alumina is taken to be the lower limit.

Subsequently, the formed aluminum carbide interacts with the silicon and aluminum oxides introduced into the mixture in a lumpy form and forms an aluminum – silicon alloy according to the total reactions:

ATSSS + 1.55 Ю2 4А1 + 1,551 + ЗСО, (2)

А14Сз + А12Оз 6А1 + ЗСО (3)

Reaction (2) proceeds when lump silica is added to the mixture of carbon-containing reducing agent and alumina, and reactions (2) and (3) are added by adding agglomerated silica-alumina raw material.

When added to a mixture containing nonvolatile carbon and alumina alumina in a mass ratio of 0.529, lump silica in a stoichiometric amount providing reaction (2), it is possible to obtain alloys with an aluminum content of up to 72%, and adding agglomerated silica-alumina raw materials provides in the alloy aluminum content more than 72%.

When smelting the mixture, which is composed of a mixture of carbon-containing reducing agent

and alumina has a ratio of non-volatile carbon and alumina less than 0.45; in an electric furnace, slag formation is noticeably enhanced due to an excess of aluminum oxide in the mixture, not provided with carbon for

Formation of aluminum carbide by reaction (1). The resulting aluminum carbide and the excess alumina mutually dissolve and create slag mixes.

Therefore, in order to avoid education in

5, a mixture of carbon-containing reducing agent and alumina of low-melting systems due to an excess of aluminum oxide, the lower limit of the ratio between the non-volatile carbon of the carbon-containing reducing agent and the alumina is assumed to be 0.45.

As the ratio of nonvolatile carbon to alumina increases in the mixture, the amount of aluminum carbide produced decreases and the fraction of free carbon increases.

5 (unrelated) non-volatile carbon, with which the oxides of bulk silica and / or agglomerated silica-alumina raw material enter into chemical interaction, forming primarily silicon carbide. Therefore, in order to avoid slagging in an electric furnace during the ore-smelting smelting process, the ratio between nonvolatile carbon and alumina and the addition of lump silica and / or agglomerated carbon dioxide

5 silica-alumina raw materials are calculated from the production of an aluminum-silicon alloy at the last stage of reduction as a result of the chemical interaction of two substances — forming silicon carbide with aluminum oxide.

The total reaction has the following stoichiometric ratios:

AI203 + 3Si02 + 9C 2AI + 3Si + 9CO (4)

5 According to reaction (4), the ratio of non-volatile carbon to alumina is 1.06. This stoichiometric ratio is taken over the upper limit of the ratio of nonvolatile carbon to alumina in the mixture.

0 In the composition of the charge, with an increase in the ratio of non-volatile carbon of a carbon-containing reducing agent to alumina above the upper limit of 1.06, both the bulk of free non-volatile carbon and oxide materials are separated in lump form. The production of aluminum-silicon alloys from the charge containing the oxide raw material in the lumpy form and the carbon-containing reducing agent in the lumpy form is accompanied by significant slagging in the electric furnace, loss of useful alloying elements, high power consumption.

Examples of the composition of the charge are given in table.1 and 2.

The proposed method for the preparation of the charge for producing aluminum-silicon alloys was tested in semi-industrial conditions and the mixture obtained by this method was smelted on a 120 kVA ore recovery furnace.

Crushed 50 kg of hard coal, 50 kg of petroleum coke are taken, and technical alumina is added in relation to the amount of nonvolatile carbon of coal and petroleum coke, equal to 0.529 in the amount of 141.8 kg. Mixed materials are mixed, a binder of -12.4 kg of technical lignosulfonate is added, the mixture is briquetted and the briquettes are dried. Lump silica (quartzite) in the amount of 62.4 kg is added to the mass of the obtained briquettes. In the resulting mixture containing briquettes and quartzite, the content of nonvolatile carbon is 100% of the stoichiometric amount of carbon needed to reduce all oxides of the charge to their metals.

To compare the results, briquettes of a known method for the production of aluminum-silicon alloys are melted.

The results are shown in table 3.

A positive result in the ore-smelting smelting of the charge prepared by the proposed method is achieved due to the fact that at the last stage of reduction the aluminum-silicon alloy is obtained as a result of the chemical interaction of aluminum carbide with silicon oxides and aluminum or

five

besides using charge in which the ratio of non-volatile carbon and alumina is at the upper limit, as a result of the interaction of silicon carbide and alumina. In addition, due to the separation in the bulk of the mixture of the formed carbides and oxides introduced into the composition of the charge in lumpy form, it is possible to avoid the formation of low-melting systems leading to slag formation in the electric furnace, and thereby increase the extraction of aluminum and silicon into the alloy alloy.

Comparing the data obtained during the tests, it is clear that using the invention, an improvement in the technical and economic performance of the process was obtained: specific energy consumption was reduced by 1.6%, briquettes by 2% and aluminum increased by 3-7%.

Formula of the invention The method of preparation of the charge for the production of aluminum-silicon alloys by carbo-thermal reduction, including the dosage of the charge materials and the binder, mixing and agglomeration of the charge, characterized in that, in order to increase the extraction of aluminum and silicon from the charge into the alloy, reduce energy consumption for the production of alloys and an increase in their aluminum content, carbon-containing reducing agent and alumina are subjected to mixing at a ratio of non-volatile carbon-containing reducing agent to alumina 0.45-1.0 6, lump silica and / or agglomerated silica-alumina raw materials are introduced up to a non-volatile carbon content in the charge of 90-115% of stoichiometric amount.

Table

Continuation of table

Table 2

Known method

The composition of the briquette,%:

Kaolin33,5 Disthen-sillimanite

concentrate14,4

Alumina15.6

Coal25.1

Petroleum coke5.8

Binding5,6 Specific consumption per 1 kg of alloy:

electricity, kWh / kg23,2

briquettes, kg / kg5.0 AI content

in the alloy,% 65

Table 3

The proposed method

Indicators

The composition of the mixture, kg: Coal50

Petroleum coke50

Alumina -141.8

Binding12,4

Ratio of non-volatile carbon of coal and petroleum coke to alumina 0.529 Addition of lump silica (quartzite), kg62.4 Content of nonvolatile carbon in the charge from stoichiometry to reduce the oxides of the charge to their metals,% 100 Specific consumption per 1 kg of the alloy: electricity, kWh / kg 22 , 83 mixtures, kg / kg 4.9 Al content in the alloy. % 72

Claims (1)

Claim A method of preparing a charge for producing aluminum-silicon alloys by carbothermal reduction, which includes the dosage of charge materials and a binder, mixing and sintering the charge, characterized in that, in order to increase the extraction of aluminum and silicon from the charge into the alloy, reduce energy costs for the production of alloys and increase their the aluminum content, the carbon-containing reducing agent and alumina are mixed with the ratio of non-volatile carbon of the carbon-containing reducing agent to alumina 0.45-1.06, lump flint is introduced I eat and / or agglomerated silica-aluminous raw materials to a nonvolatile content of carbon in the charge 90-115% of the stoichiometric amount. Table! The ratio of non-volatile carbon carbon-containing reducing agent to alumina The composition of the mixture of carbon-containing reducing agent and alumina, May. kg The addition of lump silica, kg The content of non-volatile carbon in the mixture,% of stoichiometry on rest. oxides to metals coal petroleum coke mass of non-volatile carbon in coal ⁴ and petroleum coke alumina binder 0.4 (less than the lower limit) fifty fifty 75 187.5 23.3 22.0 100 0.45 (lower limit) fifty ' fifty 75 166.7 21.0 40.4 100 Continuation of table 1 Non-volatility attitude The composition of the mixture of carbon-containing reducing agent and alumina, May. kg Lump silica supplement Non-volatile content stone oil mass of non- alumina I connect carbon coal coke volatile more ma kg carbon carbon carbon in Fichte, holding- in the cameo % of st go nom angle chiomet rebelled and oil rii on king to Mr. Coke rest. alumina i oxides to metal fishing 0.755 (average limit) 1.06 (top- fifty l 50 75 99.3 16,2 99.9 100 NIY limit) 1.7 (above ^fifty fifty 75 70.8 13.5 125.0 100 top 148.6. 100 I limit) fifty fifty 75 44.1 11.7 Table 2 Non-volatility attitude The composition of the mixture of carbon-containing reducing agent and alumina, May. kg Flavored Additive Non-volatile content stone oil mass of non- alumina I connect carbon coal coke volatile more silica carbon carbon carbon ma kg in the charge holding- in stone % of st go nom angle chiomet rebelled and oil rii on king to Mr. Coke rest. alumina oxides to metal fishing 0.4 (me- her lower - him limit) fifty fifty 75 187.5 23.3 27.6 100 0.45 (lower NIY - limit) 0.755 (average fifty fifty 75 166.7 21.0 50.7 100 limit) 1.06 (top fifty fifty 75 99.3 16,2 125.3 100 niy limit) 1.7 (above fifty fifty 75 70.8 13.5 156.8 100 upper limit) fifty fifty 75 44.1 11.7 186.3 100 Table 3 Known method The proposed method Indicators The composition of the briquette,%: The composition of the mixture, kg: Kaolin 33.5 Coal fifty Distylene Sillimanite Petroleum coke fifty concentrate 14,4 Alumina 141.8 Alumina 15.6 Binder 12,4 Coal 25.1 Non-volatility attitude Petroleum coke 5.8 carbon coal Binder 5,6 and petroleum coke to alumina 0.529 Specific consumption per 1 kg of alloy: Lump cream supplement electric power, kWh / kg 23,2 nezema (quartzite), kg 62,4 briquettes, kg / kg 5,0 Non-volatile content Contents ΑΙ carbon in the charge from in alloy,% 65 recovery stoichiometry charge oxide renewal to their metals,% 100 Specific consumption per 1 kg of alloy: electric power, kWh / kg 22,837 charge, kg / kg 4.9 Content ΑΙ in the alloy,% 72 ίδ