Recycling of Cerium and Lanthanum from Glass Polishing Sludge

To examine the efficiency of La and Ce recycling processes from the sludge, two major methods were used, namely leaching and precipitation. The findings suggest that 12% of La and 24.2% of Ce were contained in the sludge. The sludge was leached in an optimum condition of 6N HCl at a temperature of 70°C with a 3g/50 mL solid/liquid ratio for 3 h to obtain a 100% leaching recovery of La and Ce. After pH adjustment of the obtained La and Ce optimum leaching solution to 6 with NH₄OH and a simultaneous addition of H₂O₂ in a ratio of 1:1, Ce precipitated out with 65.9% recovery. On the other hand, La was not precipitated. The results obtained in this study reveal that leaching and pH adjustment method could be used to recover the valuable REE of La and Ce from glass polishing sludge in order to reach the goals of resource recycling.