Mild coal extraction for the production of anode coke

The quality and availability of petroleum coke used in the manufacture of carbon anodes for aluminum production is becoming of increasing concern to the industry. Coke quality and yields have progressively declined as changes in refinery practice and the move towards processing an increasing proportion of heavier sour crudes have affected coke properties, resulting in an increase in the metal impurities and sulfur content of the coke. An alternative supply of anode coke is required to supplement or eventually replace calcined petroleum coke. The significant world reserves of coal could represent a viable carbon resource for anode production, provided defined coke specifications can be met and at a cost that is economically viable. This paper will present an overview of the use of coal to substitute for pet coke, with a particular focus on recent efforts to producing anode grade coke through mild solvent extraction of coal.