Provided is a method for efficiently producing tungsten carbide from a raw material mixture comprising at least one valuable containing tungsten. The present invention relates to a method for producing tungsten carbide, comprising the steps of subjecting a raw material mixture comprising at least one valuable containing tungsten to electrolysis using an organic electrolytic solution to dissolve tungsten in the electrolytic solution; and calcining the electrolytic solution containing dissolved tungsten at a temperature of 800 C. or more to obtain tungsten carbide.

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.

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.

Provided are a method for crushing hard tungsten carbide (WC) scraps which is a pre-step of alkaline leaching and acid leaching processes for recycling of tungsten and cobalt, the method including mixing hard tungsten carbide (WC) scraps such as chips, wires, bolts, drills, etc., that are metalworking tools to be discarded after being used, with aluminum, followed by heating to a high temperature, to form an intermetallic compound, metal oxides, or mixtures thereof in a sponge form, and crushing the intermetallic compound, the metal oxides, or the mixtures thereof in a sponge form. Further, provided is a method for recovering tungsten and cobalt from hard tungsten carbide (WC) scrap powder through alkaline leaching and acid leaching methods.

Provided are a method for crushing hard tungsten carbide (WC) scraps which is a pre-step of alkaline leaching and acid leaching processes for recycling of tungsten and cobalt, the method including mixing hard tungsten carbide (WC) scraps such as chips, wires, bolts, drills, etc., that are metalworking tools to be discarded after being used, with aluminum, followed by heating to a high temperature, to form an intermetallic compound, metal oxides, or mixtures thereof in a sponge form, and crushing the intermetallic compound, the metal oxides, or the mixtures thereof in a sponge form. Further, provided is a method for recovering tungsten and cobalt from hard tungsten carbide (WC) scrap powder through alkaline leaching and acid leaching methods.

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).

A method of producing sodium tungstate of this invention including allowing cemented carbide scrap containing tungsten to react with a molten salt containing sodium sulfate and having added thereto a metal oxide, to thereby obtain sodium tungstate.

A method of producing sodium tungstate of this invention including allowing cemented carbide scrap containing tungsten to react with a molten salt containing sodium sulfate and having added thereto a metal oxide, to thereby obtain sodium tungstate.

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.

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.