Use of Under-Calcined Coke for the Production of Low Reactivity Anodes

Abstract

The quality of petroleum coke used for the production of anodes for the aluminium industry is declining, with both the density and the purity of the cokes affected. As a result, anodes produced from these cokes will have higher reactivity resulting in higher carbon consumption in the smelter.

Under-calcined coke can be used as a response to this higher anode reactivity. Such coke has a structure more similar to the binder phase (a mix of fine fractions and coal tar pitch), resulting in a more homogenous reactivity of all anode components following baking. The preferential consumption of the anode binder phase by the side reactions with oxygen or carbon dioxide in the cell is thus reduced.

In this paper, the theory behind the performance of under-calcined coke will be reviewed. This will be followed by results from laboratory experiments and industrial tests. Examples of the benefits obtained by plants using under-calcined coke will also be provided.