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.

The present invention relates to a method for recovering vanadium and tungsten from a leach solution of a waste denitrification catalyst, and more specifically, to a method for recovering vanadium and tungsten from a leach solution of a waste denitrification catalyst comprising the steps of: recovering vanadium by adding acid and then adding a calcium compound to a leach solution of a waste denitrification catalyst to precipitate the vanadium; and recovering tungsten by adding acid and then adding a calcium compound to the remaining leach solution after recovering the vanadium to precipitate the tungsten.

A single-heating stage method for reclaiming or recovering metals like nickel and vanadium from a petroleum waste byproduct has three steps: melting the petroleum waste byproduct in a reducing atmosphere, generating agglomerated metal in the melted byproduct, and lifting the agglomerated metal to an exposed surface of the melted byproduct. The metal precipitates out of the molten byproduct, agglomerates into a separate portion, and rises to an exposed surface of the melted petroleum waste byproduct even though the metal may have greater density than the molten petroleum waste byproduct. The original petroleum waste byproduct stratifies into a byproduct remnant and the agglomerated metal disk. The agglomerated metal disk is separable from the byproduct remnant and may be additionally separated into constituent metals in those embodiments with multiple metals in the disk.

The present invention provides a method for selective recovery of a valuable metal from a waste denitrification catalyst through alkali fusion, the method comprising the steps of: (a) adding an alkali metal to a waste denitrification catalyst, followed by mixing and alkali fusion, to generate a calcination product; (b) subjecting the calcination product to water-leaching to recover an alkali leachate and a residue; (c) adding a precipitator to the alkali leachate, followed by stirring, to recover calcium metavanadate (Ca(VO.sub.3).sub.2) or calcium tungstate (CaWO.sub.4) through precipitation; and (d) subjecting the recovered calcium tungstate to acid decomposition to prepare tungstic acid. Therefore, vanadium and tungsten can be recovered at high efficiency by a method in which a precipitator is added to a leachate, which is obtained by adding an excess amount of an alkali metal to a waste denitrification catalyst and carrying out calcination and water-leaching, and then a reaction rate is controlled.

Methods of isolating tungsten and, in particular, methods of separating tungsten and vanadium are described herein. The methods can generally comprise treating a tungsten-containing material in aqueous solution with a reducing agent suitable for the reduction of pentavalent vanadium to one or more lower oxidation states of vanadium, such that the tungsten can be more readily separated from the vanadium, e.g., via solvent extraction. In certain embodiments, the methods disclosed herein can provide tungsten, vanadium, or both tungsten and vanadium in sufficient purities for commercial use.

A single-heating stage method for reclaiming or recovering metals like nickel and vanadium from a petroleum waste byproduct has three steps: melting the petroleum waste byproduct in a reducing atmosphere, generating agglomerated metal in the melted byproduct, and lifting the agglomerated metal to an exposed surface of the melted byproduct. The metal precipitates out of the molten byproduct, agglomerates into a separate portion, and rises to an exposed surface of the melted petroleum waste byproduct even though the metal may have greater density than the molten petroleum waste byproduct. The original petroleum waste byproduct stratifies into a byproduct remnant and the agglomerated metal disk. The agglomerated metal disk is separable from the byproduct remnant and may be additionally separated into constituent metals in those embodiments with multiple metals in the disk.

The disclosure describes a method of separating and recovering valuable metals from remanufacturing solution of a spent desulfurization catalyst containing vanadium, and more particularly, to a method of separating and recovering a valuable metal from remanufacturing solution of a spent desulfurization catalyst containing vanadium, which includes: adding organic acid to a spent hydrodesulfurization catalyst after collecting the spent hydrodesulfurization catalyst in order to prepare the remanufacturing solution of the spent hydrodesulfurization catalyst; adding an extracting agent and a diluent to the remanufacturing solution to extract molybdenum and extracting vanadium from an extracted filtrate to obtain an organic phase; and adding a stripping agent to the organic phase to strip and recover vanadium.

Disclosed is a method for effectively leaching valuable metals such as vanadium and tungsten contained in a waste denitrification catalyst by using roasting and water leaching. According to the present invention, the method for leaching valuable metals contained in a waste denitrification catalyst comprises the steps of: (a) mixing a waste denitrification catalyst containing vanadium (V) and tungsten (W) in the form of an oxide with an alkali metal compound to form a mixture; (b) roasting the mixture to generate a roasting product comprising sodium vanadate (NaVO.sub.3) and sodium tungstate (Na.sub.2WO.sub.4); and (c) injecting the roasting product into water to water leach sodium vanadate and sodium tungstate in the form of a vanadate ion (VO.sub.3.sup.) and a tungstate ion (WO.sub.4.sup.2).

Methods of isolating tungsten and, in particular, methods of separating tungsten and vanadium are described herein. The methods can generally comprise treating a tungsten-containing material in aqueous solution with a reducing agent suitable for the reduction of pentavalent vanadium to one or more lower oxidation states of vanadium, such that the tungsten can be more readily separated from the vanadium, e.g., via solvent extraction. In certain embodiments, the methods disclosed herein can provide tungsten, vanadium, or both tungsten and vanadium in sufficient purities for commercial use.

A method for recovering valuable metals is disclosed. The method includes: a spent catalyst preparation step in which a spent catalyst is prepared; and a leaching step in which a first inorganic compound containing VO.sub.3.sup. is leached from the spent catalyst at a temperature of less than 100 C. under normal pressure.