SU775182A1 - Bottom mass for lining aluminium electrolyzers - Google Patents

Description

The invention relates to the field of aluminum production by electrolysis and will find application in the electrode industry in the manufacture of powder mass for tamping the bottom of aluminum electrolyzers. The known hearth mass is 1, incl. Artificial graphite, thermo anthracite, medium-temperature chamber pitch with the following component correlation, weight,%: Artificial graphite 45-65 Thermoanthracite 15-35 Coal medium-temperature pec18-24 that it does not ensure the production of bottom mass with the necessary mechanical strength. Mechanical compressive strength is 220 kg / cm. The weight for the lining of aluminum electrolysis cells 2 including the following components, wt. %; Foundry coke 30-35 Artificial graphite 5-10 Coal tar 4-7 Organic plasticizing additive 0.1-0.2 Thermoanthracite Else This mass has a high porosity, but insufficient mechanical strength in compression (the porosity is within 2628%, and the mechanical strength is It is in the order of 230 kg / cm) and is selected as a prototype. The purpose of the invention is to reduce the porosity and increase the mechanical compressive strength of the bottom mass for lining aluminum electrolyzers. This goal is achieved by the fact that the stock weight additionally contains secondary carbon material in the following ratio of components, weight. %: Coal coke15-35 Secondary carbon material — siliconized electrode production waste5-25

Coal pitch 10–25 Thermoanthracite Else As a secondary carbon material, the proposed stock contains solitized electrode production waste.

Example. To obtain hearth mass according to the proposed composition, thermoanthracite is used as fillers according to GOST-4794-75, coal coke according to GOST 3340-71 secondary carbon material — siliconized electrode production waste (SG-M grade) and stone peg coal according to GOST 10200- 73.

Properties of the starting components are listed below.

Thermoanthracite has the following properties:

The yield of volatile substances,% 0,78 The content of the eola,% 4,40 Electrical resistance, Ohm.mm2 / m980,00

Coal coke has the following properties:

Volatile matter yield,% 1.2 Ash content,% 10.8 Electrical resistance, Ohm 967

.The secondary carbon material lytic electrode production waste (brand SG-M) have the following properties:

Compressive strength.

1400

to g / cm

Electrical resistance

160 hmmvm

Chemical composition (by weight),% С

52 38 7

Sic

Si

Properties of coal tar pitch: softening temperature, ° С68.2 Volatile matter yield,% 53.4 Component composition,%

carboids 26,4

asphaltenes 30.3

Malts 43,3

Thermoanthracite, coal coke and secondary carbon material — siliconized electrode production wastes are crushed to obtain a fraction with a particle size less than 10 mm.

in tab. 1 shows the composition of the proposed mass with the extreme and optimal content of components. Table 1

Secondary carbon material — siliconized electrode industry waste

Coal tar pitch

The mass of each composition is poured into a paddle-type mixing machine with an electric heating capacity of 10 liters and mixed at 125 ° C for 40-60 minutes. The mass of the mixing machine is fed to a vertical press with a force of 100 tons and in a closed matrix at a specific pressure of 2530 kg / cm, briquettes of mm size are pressed.

Porosity,% 21 16 19 25

Strength

under compression,

kg / cm 304 373 324 230

25

20

25

15

Briquettes are cooled in air to 25-30 ° C and analyzed with the determination of porosity and mechanical strength according to the methods regulated. technical conditions 48-12-25-74 Anthracite hearth mass.

The properties of the mass with different composition, components are given in table. 2

table 2

Secondary carbon material | siliconized electrode production waste combines the unique properties of silicon carbide and graphite. Silicon carbide gives it high heat resistance and heat resistance, and graphite reports resistance to high thermal and electrical loads.

The test results are shown in Table. 2 showed that the composition of the pad mass for lining aluminum electrolysis cells provides low porosity and high mechanical strength: for the optimal composition (3) the porosity is reduced by 1.6 times and the mechanical compressive strength is 1.5 times higher than that of the prototype .

Claims (2)

1. Bottom mass for lining aluminum electrolysis cells containing thermoanthracite, coal Coke and coal tar pitch, characterized in that, in order to reduce porosity and increase mechanical compressive strength, it additionally contains secondary carbon material in the following ratio of components, wt.%: Coal carbon-155 Coal tar pitch 10–25 Secondary carbon material 5–25 Thermoanthracite Remaining 2, A sub-mass according to claim 1, characterized in that it contains siliconized electrode production waste as secondary carbon material 5. Sources of information taken into account in the examination of 1- USSR Copyright Certificate 316747, cl. C 25 C 3/06, 1970. 2. USSR author's certificate I 395504, cl. C 25 C 3/06, 1973.