Patent ID: 7485267
Filing Date: 2009-02-03
Classification: C22B,Y02P,Y02W

Abstract:
1. A method for recovering vanadium, nickel and molybdenum from a spent, unsupported catalyst that has been used in a hydroprocessing process, said catalyst having been slurried with fluid comprising water, said method comprising the steps of: a) treating said spent slurried catalyst with an aqueous solvent and an oxidizer in a leaching zone at leaching conditions; b) passing the effluent of step (a), which comprises liquid and solid material to a filtration zone, from which solid material is recovered as a filter cake; c) passing the filter cake of step (b), which comprises ammonium metavanadate to a dissolution zone, to which ammonia is added under dissolution conditions; d) passing the effluent of step (c) to a first filtration zone for removal of coke contaminants; e) passing the effluent of step (d) to a crystallization zone, wherein the effluent is adjusted for pH and ammonium metavanadate crystallizes as a solid; f) passing the effluent of step (e) to a second filtration zone for the removal of ammonium metavanadate solid; g) drying the ammonium metavanadate solid; h) calcining the dried ammonium metavanadate solid to produce vanadium pentoxide, which is removed as product; i) passing the liquid material of step (b), which comprises an aqueous phase and an organic phase, to a mixer-settler zone; j) separating the aqueous phase of step (i), which comprises molybdenum, from the organic phase, which comprises nickel; k) subjecting the organic phase of step (j), which remains in the mixer-settler zone, to at least one cycle of extraction, scrubbing and stripping prior to the removal of nickel sulfate solution as product; l) removing molybdenum compounds from the aqueous phase of step (j) by solvent extraction or precipitation.