Optimization of Purification Treatment of Spent Cathode Carbon from Aluminum Electrolysis Using Response Surface Methodology (RSM)

Purification treatment and carbon recovery of the spent cathode carbon (SCC) from aluminum electrolysis were optimized using response surface methodology (RSM) in caustic leaching process and purified further by acid leaching. The purity of treated SCC was 96.43%. A Box-Behnken design based on a single-factor experiment was utilized to model 3 independent variables, namely, temperature (55-85 degrees C), time (70-110 min), and initial alkali-material ratio (0.15-0.35), to investigate their responses to the carbon content of caustic leaching residue. A multivariate quadratic regression equation model was established according to RSM principles. Results revealed that the carbon content of caustic leaching residue was significantly influenced by the initial alkali-material ratio, temperature, and time, sorted from big to small. Interactions of any 2 of the 3 factors significantly affected the response. RSM is thus successfully applied in the optimization of the SCC impurities removal process.