Abstract: A process is disclosed for recovering metallic constituents of spent or waste catalysts containing metallic compounds fixed on an aluminous support. The process is particularly applicable for the recovery of metals such as Al, Mo, V, Ni and Co, contained in spent catalyst. The process comprises transforming the metals to be recovered into volatile chlorides by carbochlorination and then separating the chlorides obtained by dry means and fixing them successively in a selective manner. The separation of AlCl.sub.3 is accomplished by passage through granules of anhydrous NaCl, and the separation of MoCl.sub.5 by passage through granules of crystallized KCl. The process is particularly suitable for the treatment of waste catalyst from the catalytic hydrocracking or hydrodesulfurization of oils.

Abstract: A process of recovering molybdenum from waste products and particularly from spent catalyst based on active alumina and containing molybdenum compounds comprising mixing the spent catalyst with sodium carbonate powder, adding water and remixing to absorb the water in the catalyst particles, baking the mixture to convert the molybdenum present to sodium molybdate, treating the mixture at ambient temperature with carbon dioxide gas, treating the resultant mixture with hot water to dissolve the sodium molybdate, neutralizing and clarifying with concentrated nitric acid, and precipitating to produce molybdic acid high in purity that is suitable for the production of molybdenum compounds as well as for the recovery of the pure metal.

Abstract: A process of recovering molybdenum in the form of molybdic acid from waste products and particularly from spent catalysts containing a support based on gamma-alumina wherein the molybdenum is in the form of molybdenum oxide or molybdenum sulfide comprising treating the waste products with sodium carbonate and heating to convert the molybdenum present to sodium molybdate, and converting the sodium molybdate to molybdic acid by treatment with concentrated nitric acid to produce molybdic acid high in purity that is suitable for the production of molybdenum compounds as well as for the recovery of the pure metal.