Physical, chemical and X-Ray Computed Tomography characterization of anode butt cores

Three industrial anode butts, with and without recycled butt material, were studied. Non-destructive X-Ray Tomography (X-Ray CT) was used to quantify the spatial distribution of density and porosity in the sample. Apparent and absolute densities were measured and the specific pore volumes were calculated as a function of the distance from the airburn side. The results from the X-Ray CT and the densities and pore volume measurement showed a decrease in apparent density, and an increase in absolute density and specific pore volume from the center of the core to the surfaces. This work indicated that the main factors that derived the change in air and CO2 reactivities of the anodes along the electrolytic surface to the airburn surface were the concentration of the inorganic contents, e.g. sodium, calcium, etc., and the porosity of the carbon material.