Diffusion Measurements of CO2 Within Carbon Anodes for Aluminium Smelting

A study of the CO/CO2CO2diffusion coefficientsDiffusion coefficients within the carbonCarbonanodeAnode and cryoliteCryolite was carried out. Gas diffusion experiments were conducted to measure the diffusion coefficient of CO2CO2 in conjunction with anode characterizationAnode characterization using Mercury Intrusion Porosimetry (MIP). The diffusion coefficient value obtained varied from 1.38 × 10−6 m2/s to 7.89 × 10−6 m2/s in the temperature range from 25 to 960 °C. In addition, the diffusion coefficient of CO2CO2 in cryoliteCryolite at 960 °C was predicted to be 2.74 × 10−9 m2/s. Two verification studies were attempted to measure the diffusion coefficient in cryoliteCryolite, but no reliable results were obtained. The results from this study suggest the gas transport for bubble growth is controlled by gas flow in the anodeAnode due to slower diffusion coefficient value in cryoliteCryolite which is three orders of magnitude lower when gas diffusion coefficient for CO2CO2 through the anodeAnode samples.