RU2256609C1 - Method for preparing electrode mass for self-firing electrodes - Google Patents

Abstract

FIELD: electrode making industry branch, metallurgy.

SUBSTANCE: method comprises steps of baking hard carbon- containing material such as thermoanthracite, anthracite, coke, breaking them and treating in vapors of coal tar separated from liquid phase of heavy coal-tar products whose mass consists 25 -30 % of mass of hard carbon- containing materials; sieving treated carbon-containing materials, metering them and mixing with binder for 3 - 5 min at 140-180°C; shaping briquettes of melt electrode mass. Self-firing electrodes made of composition according to invention features next characteristics: density, 1.71 - 1.98 g/cm³; specific electric resistance, 73.3 - 81.4 Ohm mm²/m, compression strength, 34.1 - 35.2 MPa.

EFFECT: enhanced properties of electrodes.

3 cl, 1 tbl, 6 ex

Description

The invention relates to the electrode industry and can be used in the manufacture of electrode masses for continuous self-firing electrodes of ore-reducing electric furnaces.

A known method of producing a carbon-containing mass for the manufacture of carbon products, including grinding the carbon filler, sieving it in fractions and subsequent mixing with a binder, while the grinding process and sieving of the filler are carried out in a molten binder medium [USSR Author's Certificate No. 793934, class. From 01 to 31/02, publ. 01/07/81].

However, the electrodes made from the carbon-containing mass obtained by this method have insufficient strength and density.

The closest in technical essence and the achieved result to the claimed solution is a method for producing a carbon-containing mass, including calcining, crushing, sieving and dosing of solid carbon materials, mixing them with a binder and subsequent molding of the mass [Gasik M.I. Electrodes of ore-reducing electric furnaces. M .: Metallurgy, 1984, p.65-78].

However, the electrodes made of such a mass, after firing, are characterized by low mechanical strength and density, which leads to breaks and chips of the working end of the electrode and causes a stop and downtime of the electric furnace.

The basis of the invention is the task of improving the method of obtaining the electrode mass for self-calcining electrodes, in which the processing of the material with coal tar vapors would provide an increase in the mechanical strength and density of the electrodes, and would also increase the conductivity of the working end of the self-calcining electrode.

The problem is solved in that in the method of producing electrode mass for self-calcining electrodes, including calcining, crushing, sieving and dosing of solid carbon materials, mixing them with a binder and subsequent molding of the mass, according to the invention, the new is that after crushing solid carbon materials treated with coal tar vapors, which are isolated from the liquid phase of coal fusas at a temperature of 500-550 ° C for 2-3 hours. In this case, the mass of coal fusi is 25-30% of the mass of solid carbon material.

A causal relationship between the set of essential features of the claimed invention and the technical result that can be achieved is that in the process of processing solid carbon material with coal tar vapors, which are separated from the liquid phase of coal fuser, a surface-active adsorption layer is formed, in which contains light, medium, heavy and anthracene resin fractions. In turn, due to the attractive forces and partial vapor pressure of the resin fraction, the surface of the solid carbon material is treated, surrounding each particle with a film.

The formed surface-active layer has a high adsorption and adhesive ability, which improves the quality of the electrode mass, increases strength and increases the density of self-firing electrodes.

The carried out complex of studies showed that in the case of increasing the mass of coal fusas above 30%, the surface of the solid carbon material is oversaturated with fumes of coal tar, which leads to its sticking.

Therefore, the technology for the production of electrode mass is difficult, especially at the stage of sieving and dosing of solid carbon components of different particle size distribution.

With a decrease in the mass of coal fusas below 25%, high physical and mechanical properties of the working end of the electrode are not ensured.

At temperatures below 500 ° C, anthracene fraction of coal is not completely separated from the liquid phase and the surface layer formed is less active, and above 550 ° C, sulfur-containing resin compounds are released.

When the processing time is less than 2 hours, the complete separation of the resin fractions and the necessary surface treatment of the solid carbon material are not provided, and heating over 3 hours is impractical, since the properties of the material do not change, and an increase in the heating time leads to unproductive energy costs.

The method is as follows.

Thermoanthracite, anthracite, coke and other solid carbonaceous materials are calcined to the required temperature, then subjected to crushing, and then treated with coal tar vapor, which is extracted at a temperature of 500-550 ° C from the liquid phase of coal fuser for 2-3 hours, and the mass coal fusi constitutes 25-30% of the mass of solid carbon material. The prepared materials are scattered on drum sieves or screens, then dosed according to the types of raw materials and particle size distribution in accordance with a given mass recipe, and then, together with a binder, they are fed to a mixer, where they are mixed for 3-5 minutes at a temperature of 140-180 ° С . After the mixer, briquettes are formed from the molten electrode mass, which are sent to the finished product warehouse.

Example 1

The method is reproduced according to the above technological scheme, while solid carbon materials are treated with coal tar vapors, which are released at a temperature of 550 ° C for 3 hours, and the mass of fus is 25% by weight of the solid carbon material.

Example 2

The method is reproduced according to the above technological scheme, while the solid carbon materials are treated with coal tar vapors, which are released at a temperature of 500 ° C for 2 hours, and the mass of fus is 30% by weight of the solid carbon material.

Example 3

The method is reproduced according to the above technological scheme, while solid carbon materials are treated with coal tar vapors, which are released at a temperature of 450 ° C for 3 hours, and the mass of fus is 25% by weight of the solid carbon material.

Example 4

The method is reproduced according to the above technological scheme, wherein solid carbon materials are treated with coal tar vapors, which are released at a temperature of 550 ° C for 1 hour, and the mass of fus is 30% by weight of the solid carbon material.

Example 5

The method is reproduced according to the above technological scheme, while solid carbon materials are treated with coal tar vapors, which are released at a temperature of 550 ° C for 3 hours, and the mass of fus is 35% by weight of the solid carbon material.

Example 6

The method is reproduced according to the above technological scheme, wherein the solid carbon materials are treated with coal tar vapors, which are released at a temperature of 550 ° C for 3 hours, and the mass of fus is 20% by weight of the solid carbon material.

Samples of the electrode mass for self-firing electrodes made according to the prototype and examples 1-6 were tested. The test results are shown in the table.

Table Indicators Examples Prototype 1 2 3 4 5 6 Density, g / cm ³ 1,69 1.98 1.87 1.71 1.70 1.70 1.73 Electrical resistivity, Ohm · mm ² / m 84.2 73.3 75,2 80.2 81.4 75.9 78.5 Compressive strength, MPa 34.1 35,2 35.0 34.3 34.1 34,4 34.1

From table 1 it is seen that the use of the invention (examples 1 and 2) allows to increase the density, compressive strength, and also to reduce the electrical resistivity of self-firing electrodes made by the proposed method, in comparison with electrodes made by the known method.

Claims (3)

1. A method of obtaining an electrode mass for self-calcining electrodes, including calcining, crushing, sieving and dosing of solid carbon materials, mixing them with a binder and subsequent molding of the mass, characterized in that after crushing, the solid carbon materials are treated with coal tar vapor. 2. The method according to claim 1, characterized in that the coal tar vapors are isolated from the liquid phase of the coal fusas at a temperature of 500-550 ° C for 2-3 hours 3. The method according to claim 2, characterized in that the mass of fusible coal is 25-30% by weight of the solid carbon material.