Journals →  Tsvetnye Metally →  2022 →  #5 →  Back

ArticleName Pre-baked anode structure and properties as a function of the Blaine number
DOI 10.17580/tsm.2022.05.05
ArticleAuthor Buzunov V. Yu., Zykov S. A., Khramenko S. A.

RUSAL ETC Ltd., Krasnoyarsk, Russia:

V. Yu. Buzunov, Director, Aluminium Technology and Technical Implementation, Candidate of Technical Sciences
S. A. Zykov, Manager
S. A. Khramenko, Project manager Aluminium Technology and Technical Implementation, Candidate of Technical Sciences, e-mail:


Anode paste for pre-baked (PB) anodes represents a composite material based on calcined coke and coal tar pitch (used as a binder). A coke aggregate mix includes 3 to 5 fractions with a particle size of 12 mm down to 75 μm, and even less. Grain fractions larger than 0.2 mm form a sort of skeleton of the binder matrix and are prepared by crushing and screening. For filling the space between the grains, a dust fraction with particles less than 0.2 mm is used. The dust fraction constitutes up to 50% of the aggregate and can contain up to 70% of particles with a size of <75 μm. The dust fraction is prepared in a fine grinding circuit of ball mills. The dust fineness is determined based on the Blaine number (BN). The BN correlates with both Specific Surface Area (SSA) and Particle Size Distribution (PSD). High BN dust may account for up to 90% of the total aggregate surface area. If dust is too fine, it leads to a higher surface area of coke particles, which causes both higher particle reactivity and higher pitch demand. The above might result in higher carbon consumption. Therefore, it is important to keep a balance in terms of the particle size of the dust fraction. This paper discusses the PB anode structure and properties as a function of the BN. Lab anodes containing dust fractions with a BN of 2120, 2880, 3600, 3950 and 4700 were used for analysis. The paper presents obtained correlations between the BN and the physical, chemical and mechanical properties of PB anodes. An optimal BN of 3600 to 4200 was determined based on porosity tests of anode blocks with different BNs using mercury porosimetry; the above range can now be recommended for PB anode production.

keywords Anodes, coke aggregate, Blaine number, dust fraction, binder matrix, mercury porosimetry, pore size distribution, surface area, anode reactivity

1. Grjotheim K., Kvande H. Introduction to aluminium electrolysis. 2 ed. Düsseldorf : Aluminium-Verlag, 1993. 260 p.
2. Fischer W. K., Keller F., Perruchoud R. Baking parameters and the resulting anode quality. Light Metals. 1993. pp. 424–433.
3. Fischer F. G., Feichtinger A. R., Fischer W. K. Carbon reactivity — the combined effect of purity, structure and porous texture on reactivity investigated and generalized by means of the compsation effect. 14th Biennel Conference on Carbon, United States. 1979. pp. 165–172.
4. Engvoll M. A., Øye H. A., Sørlie M. Influence of bath contaminations on anode reactivity. Light Metals. 2001. pp. 661–667.
5. Coste B., Schneider J. P. Influence of coke real density on anode reactivity consequence on anode baking. Light Metals. 1994. pp. 583–591.
6. Chevarin F. et al. Active pore sizes during the CO2 gasification of carbon anode at 960 oC. Fuel. 2016. Vol. 178. pp. 93–102.
7. Sadler B. A., Algie S. H. Porosimetric study of sub-surface carboxy oxidation in anodes. Light Metals. 1991. pp. 594–605.
8. Azari K., Alamdari H., Ammar H., Fafard M. Influence of mixing parameters on the density and compaction behavior of carbon anodes used in aluminum production. Advanced Materials Research. 2012. Vol. 409. pp. 17–22.
9. Samanos B., Dreyer C. Impact of coke calcination level and anode baking temperature on anode properties. Essential Readings in Light Metals: Electrode Technology for Aluminum Production. 2001. Vol. 4. pp. 101–108.
10. Schmidt-Hatting W., Kooijman A., Perruchoud R. Investigation of the quality of recycled anode butts. Light Metals. 1991. pp. 251–266.
11. Hulse K. L. et al. Process adaptations for finer dust formulations: mixing and forming. Essential Readings in Light Metals, Electrode Technology for Aluminum Production. 2013. Vol. 4. pp. 322–327.
12. Yanko E. А. Anodes for aluminum cells. Moscow : Ruda i Metally, 2001. 670 p.
13. Barclay R. Anode fabrication, properties and performance. Seventh Australasian aluminum Smelting Technology Conference and Workshop, Australia. 2001. pp. 2–15.
14. Hulse K. L. Raw materials, formulation and processing parameters. Switzerland : R&D Carbon Ltd, 2000. pp. 70–80.
15. Buzunov V. Yu., Zykov S. А., Khramenko S. А., Anushenkov А. N. The use of aerodynamic turbo classifier in the production of calcined coke dust fraction. Tsvetnye Metally. 2020 No. 11 pp. 31–36. DOI: 10.17580/tsm.2020.11.05.
16. Mizonov V. Е., Ushakov S. G. Aerodynamic classification of powders. Moscow : Khimiya, 1989. 156 p.
17. Chmelar J., Foosnaes T., Oye H. A., Sandvik K. L. Coke quality effect on the grinding in an air swept ball mill circuit. Light Metals. 2005. pp. 647–652.
18. Thiel J.-P., Paepcke J., Hilck A. Changing the fineness of calcined petroleum coke with ball race mills. Light Metals. 2019. pp. 1187–1193.
19. Hulse K. L. Anode manufacture raw materials formulation and processing parameters. Sierre : R&D Carbon Ltd., 2000. 176 p.
20. Jin X. et al. Influence of ultrafine powder on the properties of carbon anode used in aluminum electrolysis. Light Metals. 2011. pp. 1141–1147.
21. Buzunov V. Yu., Zykov S. А., Khramenko S. А. Developing a technique to estimate the anode paste impregnation degree. Tsvetnye Metally. 2018. No. 11. pp. 51–54. DOI: 10.17580/tsm.2018.11.07.
22. Sadler B. A., Welch B. J. Anode consuption – practical review of the theory and anode property consideration. 7-th Australasian Aluminium Smelting Technology Conference and Workshops, Melbourne, 2001. pp. 1–42.
23. Plachenkov Т. G., Kolosentsev S. D. Porometry. Leningrad: Khimiya, 1988. 175 p.
24. Leontev N. Е. Fundamentals of filtration theory. Moscow : Izdatelstvo TsPI pri mekhaniko-matematicheskom fakultete MGU. 2009. 88 p.
25. Andersen D. H., Dedecker F., Emam S., Walderhaug M. A study of elastic and crack resistance properties of the anode carbon material. Light Metals. 2019. pp. 1205–1211.

Language of full-text russian
Full content Buy