METHOD FOR TREATING SPENT DESULFURIZAION CATALYST

PROBLEM TO BE SOLVED: To provide an economical method for treating a spent desulfurization catalyst by which the majority of the spent desulfurization catalyst can be reused without using a large quantity of water. SOLUTION: This method for treating the spent desulfurization catalyst having no desulfurizing capacity since an alumina-based desulfurization catalyst carrying metal A being an active catalyst is used for purifying petroleum hydrocarbon oil and consequently contains metal B in contaminants stuck to it comprises an oxidatively decrepitating step to oxidize metal A and metal B in the spent desulfurization catalyst into respective oxides of them and a melting/separating step to feed the spent desulfurization catalyst treated at the oxidatively decrepitating step into a heating furnace together with a melting point depressing agent and a reducing agent, melt them and separate them into an alloy containing metal A and metal B and a slag so that the separated alloy and slag are used effectively.