RU2629415C2 - Reduction melting introduction method in ore-thermal electric furnace - Google Patents

Abstract

FIELD: metallurgy.

SUBSTANCE: method includes the metering of the charging material, containing the ore part and the carbonaceous reductants, charging material loading into the furnace, carbothermic reduction to form the slug, containing the silicon carbide and silica, and the melt and the mentioned slug discharge from the furnace. Simultaneously with the reduction melting introduction, the slug viscosity is reduced by the combined loading with the charging material of the technical silicon or siliceous ferroalloys fine fractions of sizes 0-40 mm in the amount of 0.5-15.0 kg for 1 MW of the furnace active capacity.

EFFECT: invention allows to increase the technical and economic parameters of the reduction melting by reducing the slug amount in the furnace.

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Description

The invention relates to the field of metallurgy, in particular to the production of metals and alloys in ore-thermal electric furnaces, and can be used in the production of industrial silicon and silicon ferroalloys: ferrosilicon, silicochrome, silicomanganese.

A known method of producing technical silicon, including dosing of quartz or quartzite, carbon reducing agents, loading them into an electric furnace, carbothermic reduction of silicon, its release from the furnace (Vengin S.I., Chistyakov A.S. Technical silicon. M., Metallurgy , 1972, 206 p.).

A known method of producing silicon ferroalloys, which includes dosing the ore part and carbonaceous reducing agents and steel chips, loading them into an ore-thermal electric furnace, carbothermic reduction, and discharging the melt from the furnace. (Ryss M.A. Production of ferroalloys. M., Metallurgy, 1985, p. 33-58).

During the production of industrial silicon and silicon ferroalloys, part of the metal oxides introduced by the ore and ash of reducing agents is not completely restored and forms slag, which partially leaves the furnace in the process of melting products release, partially remains in the furnace, forming a skull of the furnace bath. In addition, the composition of the slag includes intermediate recovery products, such as silicon carbide. During the period when the furnaces stop for preventive maintenance and heating after repairs in the furnace bath, the temperature decreases, which reduces the degree of reduction of oxides and increases the amount of slag in the furnace. To set the optimum temperature for conducting the recovery process, the slag prevents the melt of the target product from leaving the furnace. The furnace reduces productivity, increases the consumption of raw materials and electricity.

The basis of the invention is the task of increasing the productivity of the furnace.

The technical result is to increase the technical and economic indicators of reduction smelting by reducing the amount of slag in the furnace.

The technical result is achieved by the fact that in the method of conducting reducing smelting, which includes dosing the ore part and carbonaceous reducing agents, loading them into an ore-thermal electric furnace, carbothermic reduction, releasing the melt from the furnace, according to the claimed invention, during reduction of furnace productivity into the furnace simultaneously with conducting reduction smelting load small fractions of products of reducing smelting with a size of 0-40 mm in an amount of 0.5-15.0 kg per 1 MW of active power of the furnace.

The proposed method complements a particular distinguishing feature, contributing to the achievement of the specified technical result. As products of reducing smelting can use technical silicon or silicon ferroalloys.

The method is as follows.

Fine fractions of the products of reducing melting (silicon ferroalloys or technical silicon) are melted in an electric furnace simultaneously with conducting reducing melting. The molten silicon of the finished product interacts with siliceous slag by reaction

The resulting silicon monoxide (SiO) reacts with silicon carbide slag by reaction

Thus, the additional technical silicon of the finished product loaded into the furnace destroys the silicon oxides and carbides in the slag, reducing the amount of slag due to the conversion of slag silica to a gaseous state, followed by the conversion of the slag component into the finished product. This increases the degree of extraction of silicon and ultimately leads to an increase in the productivity of the furnace.

Technical silicon of finished products loaded onto the furnace top, as it melts, when high temperatures are reached, it can evaporate, which leads to the loss of the leading element. To prevent evaporation of silicon of the finished product, after loading it on the top, close the carbonaceous reducing agent. Additional carbon binds gaseous silicon to carbide by the reaction:

This increases the degree of transition of the loaded technical silicon of the finished product into the melt.

The destruction of slag containing silica and silicon carbide, using technical silicon of finished products in an ore-thermal electric furnace simultaneously with conducting reduction smelting, is a novelty of the technical solution and has the signs of a “significant difference”.

In an ore-thermal electric furnace with a capacity of 16.5 MBA, melting technical silicon, when it was heated after a preventive repair, slag was destroyed, which prevented the melt from leaving the furnace. In addition to quartzite and carbon reducing agents, finished products (technical silicon) of various fractions were loaded onto the furnace top. The number of quartzite, carbon reducing agents and silicon loaded into the furnace was controlled, furnace productivity and the degree of assimilation of the loaded silicon were determined.

Example 1. In the furnace, in addition to quartzite and carbon reducing agents, during the period when the productivity decreased to 860 kg per hour, due to viscous slags, technical silicon of small fractions 0-40 mm was loaded in the amount of 0.25 kg per 1 MW of active furnace power. The productivity of the furnace during this period was 862 kg per hour.

The furnace in a stable period of work worked with a capacity of 870 kg per hour.

Example 2. The furnace continued to load technical silicon fines in the amount of 0.5 kg per 1 MW of power. Slag viscosity decreased. The furnace capacity was 867 kg per hour.

Example 3. The loading of fine fractions of technical silicon was increased to 5 kg per 1 MW of furnace capacity. The productivity of the furnace increased to 878 kg per hour.

Example 4. The furnace continued to load silicon fines in the amount of 10 kg per 1 MW of power. The viscosity and amount of slag is significantly reduced. The furnace capacity was 882 kg per hour.

Example 5. The loading of a fine fraction of technical silicon was increased to 15 kg per 1 MW of power. The productivity of the furnace was 894 kg per hour. Slag ceased to impede the exit of the melt from the furnace.

Example 6. The load of industrial silicon fine fraction was increased to 17 kg per 1 MW of power. The furnace capacity was 895 kg per hour.

Example 7. Produced loading technical silicon fractions of more than 40 mm in the amount of 15 kg per 1 MW of power. The furnace capacity was 881 kg per hour. The decrease in productivity is caused by the cost of electricity for the melting of silicon.

Example 8. Produced loading siliceous ferroalloy fine fraction of 0-40 mm in the amount of 10 kg per 1 MW of power. The productivity of the furnace increased at 1205 kg per hour to 1224 kg per hour. Slag in the furnace ceased to interfere with the release of the melt.

Example 9. Produced loading siliceous ferroalloys fraction 0-40 mm in the amount of 20 kg per 1 MW of power. The productivity of the furnace was 1208 kg per hour. The productivity of the furnace was not much higher than that of a technological breakdown. This is caused by evaporation of the product in case of difficulties in the release of the melt and additional energy consumption for the melting of the loaded product.

In case of difficulties with the release of the melt during the smelting of technical silicon, loading with a mixture of technical silicon or sintered ferroalloy in small fractions of 0-40 mm in an amount of 0.5-15.0 kg per 1 MW of active furnace power is optimal. The amount of loaded silicon less than 0.5 kg and more than 15 kg per 1 MW does not increase the productivity of the furnace. Performance also increases slightly when using larger classes of silicon (more than 40 mm).

Claims (1)

A method of conducting reduction smelting in an ore-thermal electric furnace, comprising dosing a charge containing an ore part and carbonaceous reducing agents, loading the charge into the furnace, carbothermic reduction to form slag containing silicon carbide and silica, and discharging the melt and said slag from the furnace, characterized in that at the same time as reducing melting is carried out, the slag viscosity is reduced by co-loading fine fractions of industrial silicon or silicon ferroalloys with a size of 0-40 mm together with a charge an amount of 0,5-15,0 kg per 1 MW oven active power.