RU1768662C - Carbonic mass for aluminium electrolyzer anodes - Google Patents

Abstract

Usage: for forming the anodes of aluminum electrolytic cells. SUMMARY OF THE INVENTION: a solvent with a boiling point of 150-350 ° C (e.g., absorption oil) is introduced into the anode paste, including the main components - coal tar pitch (binder) and electrode coke (filler), at a ratio of components, wt.% : coal tar pitch 20-24; said solvent 0.5-4.5; electrode coke - the rest. The invention allows to reduce the release of resinous substances and benzapyrine during heating and coking of the anode mass in aluminum electrolyzers. 1 tab.

Description

The invention relates to non-ferrous metallurgy, in particular to the composition of the carbon anode mass used to form the anodes of aluminum electrolysis cells.

An anode paste formulation is known in which calcined pitch and / or petroleum coke is used as filler and coal tar pitch is used as a binder, with a binder content of 26-33% in the anode mass. The disadvantage of this mass is the high content of coal tar pitch, when anodes of aluminum electrolysis cells are formed from it, this leads to an increased release of resinous substances and benzapirene from them, which worsens the working conditions in the electrolysis cells.

The anode paste formulation is known in which, by reducing the total surface of the coke-filler and plastic properties, the binder content is reduced to 23-25%. At the same time, it is known that

22% of coal tar pitch is sufficient for the formation of semicoke in the coking zone of the anode, and an excess of pitch-binder is introduced into the anode mass to give it the necessary plastic properties to ensure its spreadability when melted in the upper zone of the anode.

The anode paste formulation adopted for the prototype provides a significant reduction in emissions of resinous substances and benzopyrene from the anodes of electrolytic cells as compared to the analog, but does not provide the maximum possible reduction in the amount of emissions, since contains excess 1-3% of coal tar pitch.

The aim of the invention is to reduce the release of resinous substances and benzopyrene from the anodes of aluminum electrolysis cells.

This goal is achieved in that the composition of the carbon anode mass containing calcined electrode coke and coal tar pitch, additionally includes an environmentally friendly plasticizer from

cl

with

VI about

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oh oh

Yu

the number of solvents with a boiling point of 150-350 ° C with a ratio of components, wt.%: coal tar pitch 20-24; solvent (boiling point 150 350 ° C) 0.5-4.5; electrode coke - the rest.

Example, Take 75.5% of calcined electrode coke, 19-24.5% of coal tar pitch and 0.5-5.0% of a plasticizer, for example absorption oil, are placed in a 5 liter laboratory mixer, where they are mixed for 60 minutes while maintaining the temperature within 135-145 ° C. Toasted samples are prepared from the obtained carbon mass and their physicomechanical properties are determined.

The table shows the formulations of carbon masses and their quality characteristics. As can be seen from the table, the introduction of 0.5-4.5% plasticizer into the carbon mass composition allows a corresponding reduction in the content of coal tar pitch, while the carbon mass has the necessary plastic properties and maintains high physical and mechanical properties. By reducing the carbon tar pitch of the carbonaceous mass, the plasticizer mass is environmentally cleaner than known.

With an increase in the plasticizer content of more than 4.5% and a corresponding decrease in the content of coal tar pitch, a deterioration in the quality characteristics occurs. Thus, the anode mass loses its plastic properties, its mechanical strength decreases, and its electrical resistivity, porosity, and general destructibility in the flow of carbon dioxide increase.

When reducing the content of nlasticizer in the anode mass of less than 0.5%, the object of the invention is not ensured, because in this case, compared with the prototype, the decrease in the content of coal tar pitch is so insignificant that the decrease in emissions of resinous substances and benzopyrene will be insignificant,

The coke yield from coal tar pitch during coking of the anodes is 80-85%. The decrease in the content of coal tar pitch in the anode mass by 1% reduces the specific yield of resinous substances, including and benzapyrene, on

P 550 0.01 0, 6 kg / t of aluminum, where 550 is the specific consumption of the anode mass, kg / t of aluminum;

0.175 - the yield of resinous substances during coking of the anode mass;

0.01 - decrease in pitch content in the anode mass by 1%.

The introduction of a plasticizer into the anode mass allows, in comparison with the prototype, an average reduction in the content of coal tar pitch by 2.5%. The expected reduction in emissions of resinous substances from the anode of aluminum electrolysis cells will be in this case 9.6-2.5 24 kg per 1 ton of raw aluminum,

Claims (1)

Formula of the invention Carbon mass for the anodes of aluminum electrolytic cells, containing coal tar pitch and calcined electrode coke, characterized in that, in order to reduce the release of tarry substances and benzapyrene while maintaining the physical and mechanical properties of the anodes, it additionally contains a solvent with a boiling point of 150-350 ° With the following ratio of components, wt.%: Coal tar pitch 20-24 Solvent (boiling point) 150-350 ° C) 0.5-4.5 Electrode Coke