Abstract: A method of separating copper from chalcopyrite, including heating a mixture containing chalcopyrite particles containing copper components and hydrochloric acid at a temperature of at least 110.degree. C. for a period of time sufficient to convert the copper components into a water-soluble state. The heated mixture is then mixed with water to leach out the water-soluble copper components from the particles into water.

Abstract: The invention provides a novel method for selectively recovering molybdenum nd vanadium values from a spent catalyst used for the hydrogenation desulfurization of petroleums by the extraction with an alkaline extractant solution without the necessity of preliminary calcination of the spent catalyst containing, in addition to the molybdenum and vanadium values, nickel, cobalt and other heavy metals as well as sulfur and carbonaceous matters as the contaminants supported by or deposited on an alumina carrier. The inventive method utilizes an aqueous alkaline solution of sodium carbonate with admixture of hydrogen peroxide as an oxidizing agent whereby an unexpectedly high percent extraction is obtained for the molybdenum and vanadium values reaching 99% or higher for the former and about 85% for the latter while the extraction of nickel, cobalt and aluminum can be minimized.