Carbon Raw Material Effects on Aluminum Reduction Cell Anodes

Abstract

In recent years significant variations have been experienced in carbon anode raw material properties, namely impurities and texture of petroleum coke, and in solvent insoluble contents of coal tar pitch. Impurities increase anode consumption mainly due to increased rates of carbon/gas-phase reactions. High porosity cokes impair the mechanical properties of the anodes; nevertheless they can be utilized either by pre-grinding or by altering the aggregate granulome-try. Pitches with low levels of primary QI can be used with satisfactory results. High levels of primary QI in pitch are normally associated with increased impurity content, thus such a pitch may be objectionable for that reason. The beneficial effect of high pitch softening point was confirmed in bench-scale test electrodes with a pitch of 130°C (Mettler) softening point.