Process for separating and recovering base metals from used hydroprocessing catalyst

Abstract

A method is disclosed for separating and recovering base metals from a used hydroprocessing catalyst originating from Group VIB and Group VIII metals and containing at least a Group VB metal. In one embodiment, the used catalyst is contacted with an ammonia leaching solution to dissolve and separate the Group VIB and VIII metals from the Group VB metal complex and coke associated with the used catalyst. The resulting Group VIB and VIII metal containing solution is processed through at least two additional precipitation and liquid/solid separation steps to produce, in separate processing streams, a Group VIB metal product solution (such as ammonium molybdate) and a Group VIII metal product solution (such as nickel sulfate). Additionally, two separate filtrate streams are generated from liquid-solid separation steps, which filtrate streams are combined and subjected to hydrolysis and oxidation (oxydrolysis) to generate a purified ammonium sulfate solution for further processing, such as for fertilizer.