The use of image analysis for the optimization of pre-baked anode formulation

Carbon anodes represent about 25% of the production cost of aluminum[1]. The cost contribution is primarily that of the raw materials. The anodes are consumed during the electrolysis process and must be replaced approximately every 14-28 days depending on the size and density of the anode, and the operating parameters of the cell. Carbon anodes also present a source of electrical resistance in the cell, thereby contributing to the cost of electricity. It has been well established that anode life and electrical resistivity are optimized when the binder quantity is optimized. The aim of this research is to determine if semi-automated image analysis can be used to determine the appropriate binder quantity for a given coke particle size distribution. Samples of anode mix were taken from a bench-scale anode production process, and characterized using a microscope with semi-automated image analysis. The thickness of the pitch film around coarse coke particles was determined. Results show a minimum at the optimum binder content.