Recycling of spent bleaching clay and oil recovery

Extraction experiments were performed on spent bleaching clay to recover oil using organic solvents at optimum conditions. The bleaching efficiencies of the clays deoiled by methylethylketone (MEK), acetone, petroleum ether and hexane were 73, 65, 51 and 27%, respectively. The corresponding percentages of extracted oil were 72, 67, 60 and 42%, respectively. Reactivation of the deoiled clays by calcination was investigated at different temperatures (400-600 degrees C) and for different periods of time (15-180 minutes). The optimum values of temperature and heating time were determined for each type of deoiled clay. The bleaching efficiency of the reactivated clays varied between 86 and 94%.