Recycle of ceria-based glass polishing powder using NaOH solution

Recycle of ceria-based glass polishing powder was investigated. A waste pol ishing powder was treated in a 4 mol kg(-1) NaOH solution with a waste/NaOH weight ratio of I at 60 degreesC, and SiO2 and Al2O3 impurities were disso lved into the solution and removed from the polishing powder. A solution wh ich containing the impurities was heated to 100 degreesC, and hydroxysodali te (Na-8(AlSiO4)(6)(OH)(2)4H(2)O) was precipitate. Thus the glass polishing powder can be regenerated and hydroxysodalite was obtained as a by-product , and excess NaOH solution was reused. However addition of Si source, such as sodium silicate was required to central the leaching and precipitation p rocess.