Characterization of Dry Aggregates in Carbon Anodes by Image Analysis

Abstract

Carbon anode is one of the key components in the electrolytic production of primary aluminum. Anodes are mainly composed of dry aggregates such as calcined petroleum coke and recycled materials with pitch as the binder. Granulometry of the dry aggregates is important to obtain good physical, chemical, electrical, and mechanical anode properties. Sieving can indicate the size range of particles, but it does not reveal much information about the shape or nature of the individual particles. This article presents an image analysis technique to study not only the granulometry, but also the physical characteristics (e.g. aspect ratio, roundness, form factor, etc.) of each and every particle. The custom-made software for the image analysis can also separately identify the butt and coke particles based on different shape parameters. This technique could help track changes in granulometry at different stages of the anode production and consequently improve the quality.