The present invention relates to a method for leaching precious metals contained in a waste denitrification catalyst by using a pressure leaching process, and more specifically, to a method for leaching precious metals contained in a waste denitrification catalyst by using a pressure leaching process, the method comprising the steps of: forming a mixture by mixing a waste denitrification catalyst with a sodium salt solution; and leaching vanadium and tungsten contained in the mixture by feeding the mixture into a sealed pressurized reactor, and then heating and stirring the mixture.

There is a process for the selective recovery of transition metals from an organic stream containing transition metals. The organic stream and possibly a first extractor if solid, are melted up to the liquid state. The extractor consists of an ionic liquid or a mixture of two or more ionic liquids and the ionic liquid contains an ammonium salt as cation and as anion an anion with chelating properties. A melted organic stream and a first extractor, optionally melted, are fed to a first liquid-liquid extraction unit working at a temperature of at least 150 C. where the liquid-liquid extraction is carried out obtaining a liquid mixture containing an ionic liquid, or a mixture of two or more ionic liquids, and metals. After extraction, the liquid mixture is cooled at a temperature between 0 C. and 70 C. and becomes biphasic; then the cooled mixture is sent to a first separation unit, to separate a liquid phase that contains ionic liquids and metals, and a metal-depleted solid phase. After the first separation, the separated metal-depleted solid phase is optionally sent to a washing unit to which a solvent is fed, so as to eliminate the residual ionic liquid by transferring it into the solvent and obtaining a metal-depleted solid phase. Then the separate liquid phase containing ionic liquids and metals is sent into a liquid-liquid precipitation and separation unit, adding a counter-solvent, thereby obtaining a solid phase containing the metals and a liquid stream containing counter-solvent and ionic liquids.