RU2375503C2 - Cold-padded baked in furnace mass - Google Patents

Abstract

FIELD: metallurgy.

SUBSTANCE: invention relates to non-ferrous metallurgy field, particularly it concerns to manufacturing of carbon-base materials used for brickwork of bottom of electrolytic cell. Cold-padded baked in the hearth mass contains electro-calcined anthracite, liquid carbonic binding agent, plasticiser and special addition, liquid carbonic binding agent allows following content, wt %: coal-tar asphalt 53.3-61.7, stripping oil 37.8-43.7, antioxidative addition 0.5-3.0. In the capacity of antioxidative addition it is used boron nitride.

EFFECT: there is provided the ability of application at manufacturing of cold-padded baked in the hearth mass for filling of inter-blocked and, particularly peripheral seams in bottom of electrolytic cells and increasing of service durability of carbon bottoms at operation of electrolytic cells.

2 cl, 2 dwg, 2 tbl, 9 ex

Description

The invention relates to the field of non-ferrous metallurgy, in particular to the production of carbon materials used for lining the bottom of the cell.

The hearth mass is used to fill the space (seams) between the hearth blocks in the bottom of the cell, as well as to connect the side blocks with the hearths on the periphery of the bath.

The main problems in the operation of the electrolyzer arise due to leakage of the electrolyte and metal through interblock or peripheral joints, as well as due to the destruction of the mass during operation due to oxidation in the places of air access, for example, through bloom windows, especially this danger is great in powerful electrolyzers with large bathtubs. To eliminate these problems, a well-compacting cold-packed hearth mass is required, which expands during firing and firmly connects the hearth blocks to each other, is resistant to oxidation, with high quality indicators.

Known expanding ramming hearth for aluminum electrolytic cells (International patent RTS WO 2004/081260 A1, 2004, class C. S25C 3/08), which consists of a mixture of pitch with light oil (with a boiling point of 210-355 ° C) and filler - anthracite, calcined coke, as well as crushed anode cinder. The filler may also additionally contain from 10 to 15% of the crushed refractory material, as well as titanium dioxide, titanium diboride. The filler has a complex composition in order to obtain a printed hearth mass, well wettable by liquid aluminum. In the known composition of the packed hearth mass, a large number of components are used (3-5 items) and solid, expensive materials are also used in large quantities (for example, from 30 to 60% titanium diboride). The main disadvantage of the packed hearth mass is that a high volumetric expansion of the mass is achieved by increasing the sodium expansion of the packed hearth mass by 4 times due to the presence of 15-20% of crushed anode cinders in the filler.

Known capable of wetting and resistant to erosion and oxidation of carbon-containing composite materials used to form the cathode of the hearth (RF patent No. 2232211, 2004, class C. S25C 3/08). The invention relates to the production of carbon-containing composite materials for the production of printed paste.

The material made according to the specified patent, intended for use in the form of a packed mass, is a mixture of a carbon component with oxide reagents in a ratio of 50:50 parts by weight. A mixture of anthracite and graphite (or without it) is used as the carbon component, coal tar is used as a binder; as a raw material for obtaining a refractory material, a mixture of oxide reagents from TiO ₂ and B ₂ O ₃ (or H ₃ BO ₃ ) is used. Oxide reagents are used in the form of a mixture in stoichiometric proportions, for the subsequent production of TiB ₂ during the heat treatment and the mixture in the bath during electrolysis. Oxide reagents are pre-crushed to a state of powders with a particle size of not more than 100 microns, the most preferred average particle size of 10-30 microns. Then a mixture of oxide reagents (sometimes 3-10% Ti B ₂ is added) is mixed with carbon components (anthracite, graphite) in a ratio of 50:50 parts by weight, then mixed with coal tar and light oil and after complete mixing a carbon composite material is obtained, in particular, the stuffed mass, ready to eat.

The disadvantage of this composition of the packed mass is the use of expensive oxide components TiO ₂ and B ₂ O ₃ in large quantities (50% of the composition of the charge), which leads to unreasonable rise in the cost of the packed mass, as well as the need to provide an additional preliminary grinding operation of the oxide components to an average size particles no more than 100 microns. These oxide components TiO ₂ and B ₂ O ₃ are introduced into the composition of the mass to thermochemically obtain a composition of TiB ₂ with carbon. The mass is intended for special hearths using hearth blocks of the same composition with high erosion resistance and easily wetted by aluminum.

Also known is a carbon-containing packing material for aluminum electrolysis cells (European patent EP 0831075 A2, 1993, class C04B 35/528, C25C 3/08), consisting of one or more carbon components of the filler (graphite, anthracite), a binder (resin, pitch or other coking material) and solid powder additives (aluminum, alumina).

The use of aluminum and alumina additives in a carbon-containing packed mass is advisable if the specified mass is subjected to special high-temperature firing (above 1100 ° C) in an inert medium after compaction. It is known that alumina dissolves in the electrolyte, therefore, if the firing conditions do not provide the required strength of the connection with carbon, the resistance of the joints to the effects of the electrolyte will significantly decrease. It is known that during the electrolysis as a result of the reaction of aluminum with cryolite, liquid sodium is released, which penetrates the carbon blocks and spreads throughout the carbon cathode after about three months of operation of the electrolyzer. The greater the presence of aluminum additive in carbon, the faster the formation of two destructive compounds: aluminum carbide (Al ₄ C ₃ ) and sodium fluoride (NaF), which are known to tend to create column-forming crystals, which can lead to deformation of the hearth.

Closest to the claimed technical solution is a cold-packed hearth mass (RF patent No. 2155305, 2000, class C25C 3/08, C04B 35/52), containing the main components: electrocalcined anthracite, a liquid carbon binder, a plasticizer and a special additive.

The main disadvantage of this mass is insufficient ductility, low volume expansion due to the specifics of its application. The mass is designed to connect semi-graphite (with a graphite content in the formulation of not more than 30%) and amorphous (anthracite) hearth blocks, has low oxidation resistance and is not intended to connect graphite and graphite hearth blocks.

In the context of the development of new designs of powerful electrolyzers, designed to operate at a current strength of 300 kA and above, as well as increased anode current densities, the latest generation hearth blocks, graphite and graphite, are used for lining the bath.

The surface properties of graphite and graphitized hearth blocks differ significantly from the surface properties of amorphous and semi-graphite blocks (based on thermo- and electrocalcined anthracite), primarily, with a smaller area of areas that are easily wetted by a coal-tar binder and sintered with a hearth mass. Accordingly, when connecting the bottom graphite and graphite blocks with the bottom mass (according to the prototype), the density and strength of the connection will not be achieved due to the low expansion of the mass during firing, which during operation of the mass can lead to the formation of gaps between the mass and the block and the electrolyte leaks.

Hearth blocks in powerful bathtubs are also subject to significant oxidative effects of the environment during operation, which leads to an additional risk of fracture of the joints. Accordingly, for lining the bottoms of powerful electrolyzers, hearth blocks and cold-packed hearth masses are required that are more resistant to oxidation than for electrolyzers with amorphous blocks.

The objective of the invention is to increase the operational properties of the cold-packed hearth mass in the interblock seams by improving the physico-mechanical properties, providing, ultimately, increased battery life.

The technical result consists in obtaining a cold-packed hearth mass having high ductility (compactibility) during tapping, increased volumetric expansion during firing and increased resistance to oxidation.

The specified technical result in the implementation of the invention is achieved by the fact that the cold-packed hearth mass, including electro-calcined anthracite, a liquid carbon binder, a plasticizer and a special additive according to the claimed invention contains a liquid carbon binder of the following composition, wt.%:

coal tar pitch 53.3-61.7 absorption oil 37.8-43.7 antioxidant supplement 0.5-3.0

Boron nitride can be used as an antioxidant additive.

The inventive mass differs from the prototype composition, namely the presence of additives in the composition of the liquid carbon binder, with the claimed ratio of all components, therefore, it meets the condition of "novelty."

The specified amount of antioxidant additives in the liquid carbon binder is optimal and is due to requirements for the use and operation of the hearth mass.

The analysis of the prior art by the applicant, including a search by patents and scientific and technical sources of information and identification of sources containing information about analogues of the claimed invention, allowed to establish that the applicant did not find an analogue characterized by features identical to all the essential features of the claimed invention.

To verify the compliance of the claimed invention with the criterion of "inventive step", the applicant conducted an additional search for known solutions that match the distinctive features of the claimed substance from the prototype. The search results showed that the claimed invention does not follow explicitly from the prior art for the specialist, since the influence of the transformations provided for by the essential features of the claimed invention on the achievement of the technical result is not revealed from the prior art determined by the applicant. The described invention is not based only on a change in the quantitative trait. New values of these signs could not be obtained on the basis of known dependencies.

Therefore, the claimed invention meets the condition of "inventive step"

The use in the proposed cold-packed hearth mass of a liquid carbon binder containing an antioxidant additive, with the claimed ratio of components, provides a new effect - an increase in the ductility of the cold-packed hearth, oxidation resistance and volume expansion during firing, which are not inherent in the cold-packed hearth of the prototype.

The use of antioxidant additives is due to the implementation of the necessary permissible degree of interaction between the components of the binder without a sharp change in component composition and the technology for producing cold-packed hearth mass.

The liquid carbon binder should ensure the wettability and uniform distribution of electrocalcined anthracite in the volume of the hearth mass and should be evenly distributed in the volume of the hearth mass, which guarantees the ductility of the cold-packed hearth mass after preparation, compaction during filling in joints and volumetric expansion of the mass during firing. The physicomechanical properties of the liquid binder are represented by viscosity characteristics at 50 ° C and the yield of coke residue.

Accordingly, to ensure the required operational properties of the cold-packed hearth mass, the preparation is carried out under equivalent viscosity conditions, i.e. in a narrow range of viscosity binder. The viscosity of a liquid carbon binder depends on the ratio of all components - coal tar pitch, absorption oil, antioxidant additives.

An excess of coal tar pitch (more than 61.7%) with an insufficient amount of absorption oil (less than 37.8%) leads to a significant increase in the viscosity of the liquid carbon binder with a slight increase in the yield of coke residue. The higher the content of coal tar pitch in a liquid carbon binder, the higher the yield of coke residue, but the viscosity of the liquid carbon binder sharply increases. A binder having a high viscosity is poorly distributed in electrocalcined anthracite, as a result of its mixing, neuromeses are formed, which are sticky lumps of thick binder and electrocalcined anthracite. When stuffing in the seams, the cold-packed hearth mass with non-impurities “floats” under the rammer, does not condense, which after firing results in a loose seam.

The lack of coal tar pitch (less than 53.3%) with an excess of absorption oil (more than 43.7%) leads to the production of a liquid carbon binder with a low viscosity. A liquid carbon binder with a low viscosity mixes well with electro-calcined anthracite, forming a plastic cold-packed hearth mass, but during the tamping of such a mass, the effect of “sand” is observed (the mass is poured under the rammer in the seam volume), and when firing the cold-packed hearth mass in the seams, low-viscosity liquid carbon the binder begins to migrate along the height of the sealed seam from top to bottom. As a result, the upper layer of the cold-packed hearth depleted in a liquid carbon binder has a low yield of coke residue and is easily destroyed after firing.

The second indicator characterizing the achievement of physical and mechanical properties due to the sinterability of the liquid carbon binder with electrocalcined anthracite, the coke residue of the liquid carbon binder, also has a lower acceptable limit. The presence of an antioxidant additive in an amount of 0.5-3.0% provides the effect of increasing the yield of coke residue while maintaining the viscosity of the liquid carbon binder in the optimal range.

It has been experimentally established that the maximum effect of increasing the oxidation stability of a cold-packed hearth mass is achieved by introducing an antioxidant additive into a liquid carbon binder with the stated ratio of components.

As an antioxidant additive in a liquid carbon binder, boron nitride can be used as a neutral substance at temperatures up to 900 ° C, which significantly increases the yield of coke residue during heat treatment of the binder to 995 ° C, acting as a catalyst, and helps to increase the resistance of the calcined cold-packed hearth mass to oxidation. Boron nitride is convenient to use, has a low cost.

Coke formed during the heat treatment of a liquid carbon binder forms compounds with reduced boron oxide B ₂ O ₃ , the precursor of which is a special additive, for example, boric acid (H ₃ BO ₃ ), distributed in the composition of a cold-packed hearth mass.

Boron nitride protects carbon from interaction with aluminum, since it is not wetted by aluminum, and due to the formation of covalent bonds with carbon, it significantly strengthens the carbon composition that it contains.

To achieve uniform distribution, boron nitride is introduced into a liquid carbon binder at a temperature of 180-200 ° C. During firing, compounds of carbon with boron nitride in a cold-packed hearth mass are oxidized under the influence of an oxidizing environment, forming a glassy substance containing boron oxide at the contact sites that is very resistant to oxidation. The oxidation process with the formation of an additional substance takes place with an increase in volume expansion. The optimal content of an antioxidant additive, boron nitride, is determined by both the chemical processes of interaction with carbon and the aggregative stability of the prepared liquid carbon binder.

The introduction of an antioxidant additive in a binder of less than 0.5% increases the viscosity of the liquid carbon binder, but does not affect the yield of coke residue. The lack of antioxidant additives (less than 0.5%) does not lead to a positive effect, i.e. increase in volume expansion and decrease in oxidizability of the cold-packed hearth mass, as it is distributed in a liquid carbon binder to a concentration insufficient for interaction with the components of coal tar pitch.

Exceeding the content of boron nitride (more than 3.0%) in a liquid carbon binder leads, due to its great dispersion, to a sharp increase in viscosity and loss of aggregate stability of the liquid carbon binder, which is expressed in the formation of a precipitate.

The high viscosity of the liquid carbon binder with the precipitate prevents its mixing with electrocalcined anthracite, requires an increase in the temperature of preparation and the use of a cold-packed hearth mass, i.e. new technology.

The compositions of the proposed masses, as well as masses with an exorbitant content of antioxidant additives are shown in table 1. Examples of obtaining cold-packed hearth masses.

Example 1. To prepare the mass using the following components in the ratio, wt.%:

electrocalcined anthracite 83.0 plasticizer 1,5 special additive 1,5 liquid carbon binder fourteen

The mixture of electro-calcined anthracite has a specific surface area of 150 m ² / kg. Properties of electrocalcined anthracite:

true density 1.88 g / cm ³ electrical resistivity 545 μΩ · m ash content 5.4%

As plasticizer, diethylene glycol with a density at 20 ° C of 1.12 g / cm ³

As a special additive in electrocalcined anthracite

use boric acid - H ₃ IN ₃ .

Use a liquid carbon binder of the following composition wt.%:

brand B coal tar pitch (GOST 10200) 61.7 absorption oil (TU 14-107-148) 37.8 antioxidant additive - boron nitride (BN) (TU 212-003-19534204-2002) 0.5

The preparation of a liquid carbon binder is carried out as follows: grade B coal tar melt (GOST 10200) (with a softening temperature of 76 ° C according to the KiS method) at a temperature of 155-165 ° C is introduced an absorption oil with a temperature of 60-70 ° C and the resulting composition is mixed for 3-5 hours at a temperature of 160-180 ° C until a homogeneous mixture is obtained. Boron nitride is added to the resulting mixture and further mixed until the antioxidant additive is evenly distributed and there are no white streaks on the surface of the liquid carbon binder.

The liquid carbon binder, according to the claimed composition with 0.5% antioxidant additives, is uniform in color and composition and has the following properties:

viscosity at 50 ° C 400 cps; coke residue output 34.6%

Preparation of the mass in laboratory conditions is as follows: in a laboratory mixing machine with Z-shaped blades with a capacity of 10 l, electrocalcined anthracite is loaded, then a special additive, boric acid, is added, and the mixture is mixed for 5 minutes. Lastly, a plasticizer - diethylene glycol is introduced, the mixture is mixed, and a previously prepared liquid carbon binder with an antioxidant additive of boron nitride is poured into the machine. Mixed at a temperature of not more than 80 ° C for 25 minutes, the cold-packed hearth mass is ready for use.

Tests of the cold-stuffed hearth mass are carried out in accordance with accepted control methods.

The mass compaction is determined on a Fischer machine according to the R&D Carbon MVI by determining the density of the cold-packed hearth mass after 50 and 100 strokes and calculating the compaction by the formula:

K = (D ₁₀₀ -D ₅₀ ) / D ₅₀ × 100,

Where D ₁₀₀ is the apparent density of the unfired cold-packed hearth mass after 100 strokes;

D ₅₀ is the apparent density of the unfired cold-packed hearth mass after 50 strokes.

Physico-mechanical properties according to TU 1914-071-05785218-99.

For this, samples are pressed in the matrix at a pressure of (19.6 ± 2.0) MPa; and prepress time 120 ± 5 seconds, at a temperature of 25 ° C.

The determination of the physicomechanical parameters of the cold-packed hearth mass is carried out on samples with a diameter of 60 and a height of 30 mm.

Dilatometric tests are carried out according to the method of MVI "KGATSMiZ" on unfired samples with a diameter of 50 mm and a height of 50 mm. The results of determining the volume-linear expansion of the cold-packed hearth mass during firing are presented in figure 1.

The heat treatment of the samples is carried out by firing in carbon powder to a temperature of 980 ° C at a rate of 100 ° C / h and holding at a final temperature for 3 hours.

Open porosity is determined according to GOST 2409-95.

Oxidation resistance is tested according to ISO 12988 on calcined samples.

Resistance to the effects of cryolite-alumina melt is determined on calcined samples according to the procedure TU 48-12-21-95.

Example 2. As in example 1. The difference is that they use a liquid carbon binder of the following composition, wt.%:

brand B coal tar pitch (GOST 10200) 58.2 absorption oil (TU 14-107-148) 38.8 antioxidant additive - boron nitride (BN) (TU 212-003-19534204-2002) 3.0

Liquid carbon binder has the following properties:

viscosity at 50 ° C 550 cps; coke residue output 38.6%

The preparation of a cold-packed hearth mass is carried out under industrial conditions under the following conditions: electrocalcined anthracite with a specific surface of 150 m ² / kg is loaded into a batch mixer and mixed for 10 minutes, then a special additive (boric acid) is poured. At the same time, the plasticizer charge is started and mixed for 15 minutes. At the end of time, a liquid carbon binder is added, with which the mass is mixed for another 20 minutes. The total mixing time is not more than 45 minutes.

Example 3. As in example 1. The difference is that they use a liquid carbon binder of the following composition, wt.%:

brand B coal tar pitch (GOST 10200) 53.3 absorption oil (TU 14-107-148) 43.7 antioxidant additive - boron nitride (BN) (TU 212-003-19534204-2002) 3.0

Preparation of a liquid carbon binder is as follows.

Absorption oil with a temperature of 70-75 ° C is introduced into the melt of brand B coal tar pitch (GOST 10200) (with a softening temperature of 89 ± 1 according to the KiS method) at a temperature of 200 ° C and the resulting composition is mixed for 4.5-5 hours at a temperature of 185-190 ° C until a homogeneous mixture is obtained. Boron nitride is added to the resulting mixture and further mixed until the additive is uniformly distributed and there are no white streaks on the surface of the liquid carbon binder. Liquid carbon binder has the following characteristics:

viscosity at 50 ° C 520 cP; coke residue output 38.0%.

Example 4. As in example 3. The difference is that they use a liquid carbon binder of the following composition, wt.%:

brand B coal tar pitch (GOST 10200) 57.7 absorption oil (TU 14-107-148) 41.8 antioxidant supplement boron nitride (BN) (TU 212-003-19534204-2002) 0.5

Liquid carbon binder has the following characteristics:

viscosity at 50 ° C 400 cps; coke residue output 35.0%

Example 5. As in example 1. The difference is that they use a liquid carbon binder of the following composition, wt.%:

brand B coal tar pitch (GOST 10200) 59,4 absorption oil (TU 14-107-148) 39.6 antioxidant additive - boron nitride (BN) (TU 212-003-19534204-2002) 1,0

Liquid carbon binder has the following characteristics:

viscosity at 50 ° C 530 cps; coke residue output 38.2%

Example 6 (going beyond). As in example 1. The difference is that they use a liquid carbon binder of the following composition, wt.%:

brand B coal tar pitch (GOST 10200) 59.8 absorption oil (TU 14-107-148) 39.9 antioxidant additive - boron nitride (BN) (TU 212-003-19534204-2002) 0.3

Liquid carbon binder has the following characteristics:

viscosity at 50 ° C 410 cps; coke residue output 34.0%

Example 7 (going beyond). As in example 3. The difference is that they use a liquid carbon binder of the following composition, wt.%:

brand B coal tar pitch (GOST 10200) 53.1 absorption oil (TU 14-107-148) 43,4 antioxidant additive - boron nitride (BN) (TU 212-003-19534204-2002) 3,5

Liquid carbon binder has the following characteristics:

viscosity at 50 ° C 720 cps; coke residue output 39.2%

Example 8 (going beyond). As in example 3. The difference is that they use a liquid carbon binder of the following composition, wt.%:

coal tar pitch with temperature softening 90 ° C (according to KiS) 62.0 absorption oil (TU 14-107-148) 37.5

antioxidant additive -

boron nitride (BN) (TU 212-003-19534204-2002) 0.5

To prepare the binder, high-temperature pitch with a softening temperature of 90 ° C (according to KiS) of a foreign manufacturer is used. Liquid carbon binder has the following characteristics:

viscosity at 50 ° C 896 cps; coke residue output 38.8%

Example 9 (going beyond). As in example 1. The difference is that they use a liquid carbon binder of the following composition, wt.%:

brand B coal tar pitch (GOST 10200) 54,2 absorption oil (TU 14-107-148) 44.0 antioxidant additive - boron nitride (BN) (TU 212-003-19534204-2002) 1.8

Liquid carbon binder has the following characteristics:

viscosity at 50 ° C 320 cps; coke residue output 32.4%

An example of a prototype.

The mass is prepared on the basis of electro-calcined anthracite with an external specific surface of 100 m ² / kg.

Properties of electrocalcined anthracite:

true density 1.98 g / cm ³ electrical resistivity 545 μΩ · m ash content 4.0%

The mass is prepared from 89% of the mixture of electro-calcined anthracite, 0.4% of plasticizer (diethylene glycol), 0.6% of a special additive (boric acid), 10% of a liquid carbon binder.

A liquid carbon binder of the following composition is used, wt.%:

brand B coal tar pitch (GOST 10200) 60.0 absorption oil (TU 14-107-148) 40,0

with the following properties:

viscosity at 50 ° C 400 cps; coke residue output 34.0%

Preparation of the mass is carried out in laboratory conditions as follows: in an unheated mixing machine with a capacity of 10 l, electrocalcined anthracite of the indicated specific surface is loaded, mixed, a special additive is loaded, then a plasticizer and mixed for 5 minutes. A liquid carbon binder with a temperature of 50 ° C is loaded last. The mass is mixed for 35 minutes without heating.

After mixing, the cold-packed hearth is ready to eat. The tests are carried out in accordance with the quality control methods of carbon lining materials. The tests are carried out on samples of cold-packed hearth mass obtained by pressing in a blank matrix.

Apparent density is determined on samples with a diameter of 60 mm, a height of 60 mm.

Resistance to cryolite-alumina melt is determined by the method described in TU 48-12-21-95.

The proposed compositions of a liquid carbon binder with a different content of antioxidant additives for the examples shown in table 1.

Physico-mechanical characteristics of the cold-packed hearth mass prepared on the basis of the claimed compositions of the liquid carbon binder are shown in table 2.

The results of dilatometric tests of cold-stuffed hearth mass according to example 1 are presented in figure 1, for the prototype - in figure 2.

The data in table 2 show that the proposed masses (examples 1-5) are characterized by increased compaction during tapping, which results in the achievement of the optimal range of the coefficient of compaction of the mass according to the Fisher test (2-6). The main effect of the use of a special antioxidant additive - boron nitride - increased oxidation resistance is achieved in examples 1-5, as evidenced by a significant increase in the CRR value of the residue after the reaction in CO ₂ , as well as a decrease in the rate of crumbling after the reaction in CO ₂ . In general, the reactivity of the mass (CRL) is significantly reduced in the presence of boron nitride in the composition of the cold-packed hearth mass.

The presence of an antioxidant additive also leads to volume expansion of the mass during firing.

Going beyond the claimed limits for the content of antioxidant additives (examples 6, 7) does not ensure the achievement of the required technical result.

Going beyond the claimed limits for the content of coal tar pitch and absorption oil in a liquid carbon binder (examples 8, 9) does not ensure the achievement of the required technical result.

The examples show (Table 1) that the antioxidant additive, boron nitride, improves the quality of the liquid carbon binder, obtained on the basis of both medium-temperature coal tar pitch (grade B) and high-temperature coal tar pitch (grade B), significantly increasing the yield of coke residue when a slight increase in the viscosity of the liquid carbon binder within the requirements for this indicator.

The invention is applicable in the manufacture of cold-packed hearth masses for filling interblock and peripheral joints in the bottom of electrolytic cells, especially with graphite and graphitized hearth blocks, and allows to increase the operational resistance of carbon bottom in the operation of electrolytic cells.

Table 1 Examples Coal tar pitch, wt.% Absorption oil, wt.% Boron nitride, wt.% The dynamic viscosity of the binder, SP The yield of coke residue from the binder,% one 61.7 37.8 0.5 400 34.6 2 58.2 38.8 3.0 550 38.6 3 53.3 43.7 3.0 520 38,0 four 57.7 41.8 0.5 400 35.0 5 59,4 39.6 1,0 530 38,2 6 (exit) 59.8 39.9 0.3 410 34.0 7 (exit) 53.1 43,4 3,5 720 39.2 8 (exit) 62.0 37.5 0.5 896 38.8 9 (exit) 54,2 44.0 1.8 320 32,4 According to the prototype 60.0 40,0 0 400 34.0

table 2 Examples The coefficient of compactibility, K,% Density is apparent adore. mass, g / cm ³ Volumetric expansion during firing,% Resistivity, μOhm · m Open porosity,% CRR residue after reaction in CO ₂ ,% CRD-showability after reaction with CO ₂ ,% CRL reactivity in CO ₂ ,% Relative elongation (sodium expansion)% Example 1 3.2 1.42 1.09 74.3 19.0 38,0 44.8 17,2 0.56 Example 2 4.2 1.44 1.38 71.6 18.2 46.8 40,2 13.0 0.51 Example 3 5.1 1.45 1.24 72.0 18.0 45.9 39.5 14.6 0.50 Example 4 3.0 1.40 1.40 76.5 18.5 38.5 45,2 16.3 0.57 Example 5 3.6 1.44 1.42 73,2 18.9 52.3 30.9 16.8 0.59 Example 6 2.0 1.40 0.50 79.0 19.0 26.6 54.6 18.9 0.64 Example 7 1.4 1.25 0.20 85.0 24.0 10,4 65,4 24.2 The sample crumbled Example 8 The sample is not molded due to the high viscosity of the mass. Example 9 6.2 1.33 0.30 90.0 25.1 The sample crumbled during testing 1,0 Example 10 1,0 1.25 0.05 91.5 26.0 10,2 65.0 24.8 0.81 Prototype 2.0 1.40 0.50 79.0 19.0 26.5 54.7 18.8 0.65

Claims (2)

1. Cold-packed hearth mass, including electro-calcined anthracite, a liquid carbon binder, a plasticizer and a special additive, characterized in that it contains a liquid carbon binder of the following composition, wt.%:
coal tar pitch 53.3-61.7 absorption oil 37.8-43.7 antioxidant supplement 0.5-3.0 2. The mass according to claim 1, characterized in that boron nitride is used as an antioxidant additive.

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