Method of separately recovering metal values of petroleum refining catalyst

The method of recovering vanadium, iron, nickel, cobalt, aluminum, molybdenum and tungsten metal values from spent hydrodesulphurization catalyst which comprises the steps of contacting the catalyst with aqueous HCl at temperature near the aqueous acid boiling point and thereby dissolving substantially all the values of metals other then molybdenum sulfide or tungsten values, carbon and silica, adding to the leach solution a source of sulphur selected from the group consisting of sodium sulfide, sodium hydrogen sulfide and a combination of hydrogen sulfide and caustic soda and thereby precipitating nickel and cobalt sulfides under atmospheric pressure while the solution pH is in the range of 1-2.5 separating and removing the resulting sulfide precipitate from the leach solution, then adding to the leach solution caustic soda and an oxidant and thereby precipitating vanadium and iron in the solution in the form of redcake in which the vanadium is in the pentavalent state, separating and removing the redcake from the liquid phase, and recovering aluminum values from the liquid phase.

The method of recovering metal values from spent hydrodesulfurization catalyst containing alumina, and sulfides of iron, cobalt, vanadium, nickel and molybdenum or tungsten which comprises the steps of contacting the catalyst with aqueous HCl at temperature near the aqueous acid boiling point as a primary acid leach stage and thereby dissolving substantially all the aluminum and other metal values except those of molybdenum or tungsten, and separating and removing the resulting primary acid leach solution form the primary acid leach residue consisting mainly of molybdenum sulfide or tungsten values, oxidizing the iron contained in the solution to the ferric stage, selectively removing the ferric iron from the liquid phase, then oxidizing the vanadium contained in the liquid phase to pentavalent form and precipitating it as redcake, separating and removing the redcake from the liquid phase, selectively separating and removing cobalt from the liquid phase following redcake separation, then adding a source of sulfur to the liquid phase and thereby precipitating the nickel as nickel sulfide, separating the nickel sulfide product from the liquid phase and finally recovering aluminum values from the liquid phase.

The method of recovering metal values from spent hydrodesulfurization catalyst containing alumina and sulfides of iron, cobalt, vanadium, nickel, molybdenum or tungsten which comprises the steps of contacting the catalyst with aqueous HCl at temperature near the aqueous acid boiling point as a primary acid leach stage and thereby dissolving all the aluminum and other metal values except those of molybdenum or tungsten, separating and removing the resulting primary acid leach solution from primary acid leach residue, oxidizing the iron in the said leach solution to the ferric state, selectively removing the iron in the ferric state from the solution, oxidizing the vanadium to the pentavalent state and precipitating redcake, separating the redcake from the liquid phase, selectively removing cobalt from the liquid phase, then selectively removing nickel from the liquid phase, and finally recovering the aluminum values from the barren solution following the removal of the nickel values therefrom.

The method of recovering molybdenum, cobalt, nickel, and vanadium values from spent hydrorefining catalyst containing Group VIB and iron group metals in the sulfide form which comprises the steps of contacting the catalyst with aqueous HCl at temperature near the aqueous acid boiling point in a primary acid leach stage and thereby dissolving substantially all the values of metal other than those of molybdenum and tungsten, separating and removing from the primary acid solution the resulting primary acid leach residue consisting mainly of molybdenum sulfide, removing from the primary acid leach residue substantially all the molybdenum values, contacting the resulting substantially molybdenum-free leach solution with a first solvent extractant and thereby extracting the cobalt and iron values contained therein, contacting the raffinate from the cobalt and iron solvent extraction step with an oxidant and thereby oxidizing the vanadium values thereof to the tetravalent state, contacting the resulting solution with a second solvent extractant and thereby extracting the vanadium values in the said solution, then recovering the nickel values in the vanadium extraction raffinate, and finally recovering the aluminum values from the barren liquor remaining after the nickel separation and removal.