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BINDER MATRIX REACTIVITY UNDER CO2 GASIFICATION: A POSSIBLE EXPLANATION
OF THE ANODE DISINTEGRATION IN THE ELETROLYSIS BATH IN HALL-HEROULT
PROCESS
F. Chevarin1,2, M. Kavand1,2, D. Ziegler3, M. Fafard2, H. Alamdari1,2*
Department of Mining, Metallurgical and Materials Engineering, Université Laval, 1065 avenue de la
Médecine , Québec, QC, G1V 0A6, Canada
1
NSERC/Alcoa Industrial Research Chair MACE3 and Aluminum Research Centre – REGAL Université
Laval, 1065 avenue de la Médecine, Québec, QC, G1V 0A6, Canada
2
(*[email protected])
3
Alcoa Primary Metals, Alcoa Technical Center, 100 Technical Drive, Alcoa Center, PA, 15069-0001,
USA
ABSTRACT
Carbon anodes, used in the Hall-Heroult process, are essentially consumed by the electrochemical reaction
to produce metallic aluminum. It is also consumed by parasitic reactions with air and CO2. The carbon
anode is made of petroleum coke with different particle sizes, butts (recycled anodes) and coal tar pitch.
The mixture of fines particles (fewer than 150 µm) of coke together with the pitch material form a matrix,
binding the large coke particles together. It is generally though that the binder matrix is more reactive than
the other anode constituents. This conjecture was not clearly proved in the literature. The present study is
focused on the CO2 reactivity of binder matrix and anode constituents at 960 °C, both under chemical
regime (100% of CO2) and under a concentration gradient (diffusion). The apparent reaction rates of these
materials were measured. The role of the binder matrix in anode consumption and its disintegration
(dusting phenomenon) was discussed.
KEYWORDS
Binder matrix, CO2 reactivity, anode, coke, pitch, chemical regime, diffusion