Abstract: The feasibility of solvent technology treatment of oily spent clay by ultrasonic assisted was studied. The influences of the ultrasonic frequency, solvent dosage, treatment temperature and time as well as treatment times on the oil yield were investigated. The results indicated that the optimal treatment conditions were as follows: 30℃, extract time 10 min, 100g spent clay, ultrasonic frequency 68 kHz, solvent dosage 80 mL, twice extract with nonpolar solvent, and then extract with a mixed solvent two times. Under these conditions, the total oil recovery amount was 30.4 g. For the same effect, a higher temperature and longer treatment time an d more solvents are required just with traditional stirring method. The ideal oil extracted from spent clay possessed characteristics as naphthenic base oil; the regenerated clay recovered most of its adsorption capacity, and could be reused for lubricating oil refining. It is concluded that the ultrasonic assisted solvent treatment of spent clay is technically feasible and economically advantageous.

Key words: spent clay, ultrasound, solvent, recovery rate, regeneration