Abstract: A powder containing tungsten carbide has an Fsss particle size of greater than or equal to 0.3 ?m and less than or equal to 1.5 ?m, and a content rate of the tungsten carbide of greater than or equal to 90% by mass. The powder has a crystallite size (average particle diameter) Y satisfying a relational expression of Y?0.1×X+0.20 (X: the Fsss particle size of the power containing tungsten carbide).

Abstract: A powder containing tungsten carbide has an Fsss particle size of greater than or equal to 0.3 ?m and less than or equal to 1.5 ?m, and a content rate of the tungsten carbide of greater than or equal to 90% by mass. The powder has a crystallite size (average particle diameter) Y satisfying a relational expression of Y?0.1×X+0.20 (X: the Fsss particle size of the power containing tungsten carbide).

Abstract: Provided are a method for producing sodium tungstate by supplying an oxidant made of sodium nitrate or sodium nitrite to bring a tungsten containing material and the oxidant into contact with each other in an atmosphere containing oxygen to thereby continuously produce a reaction product; a method for collecting tungsten using the method; and an apparatus for producing sodium tungstate. Also provided are a method for producing a sodium tungstate aqueous solution in which a reductant is introduced into a melt containing the above-described reaction product which is then dissolved in water; and a method for collecting tungsten using the method.

Abstract: Provided are a method for producing sodium tungstate by supplying an oxidant made of sodium nitrate or sodium nitrite to bring a tungsten containing material and the oxidant into contact with each other in an atmosphere containing oxygen to thereby continuously produce a reaction product; a method for collecting tungsten using the method; and an apparatus for producing sodium tungstate. Also provided are a method for producing a sodium tungstate aqueous solution in which a reductant is introduced into a melt containing the above-described reaction product which is then dissolved in water; and a method for collecting tungsten using the method.

Abstract: A method for producing an ammonium tungstate aqueous solution includes the steps of: adding sulfuric acid to a solution containing tungstate ions; bringing the solution having the sulfuric acid added therein, into contact with an anion exchange resin; and bringing the anion exchange resin into contact with an aqueous solution containing ammonium ions.

Abstract: There are provided a cemented carbide high in thermal diffusivity and excellent in wear resistance, and a cutting tool including a base material formed of this cemented carbide. The cemented carbide is a WC based cemented carbide in which a hard phase mainly constituted of WC grains is bound by a binder phase mainly constituted of Co, and is used for a cutting tool. The binder phase is substantially constituted of Co, or Co and Ni. A total content of Co and Ni is not less than 4.5 mass % and not more than 15 mass %. In this cemented carbide, the WC grains have an average diameter of not less than 0.4 ?m and not more than 4 ?m.

Abstract: Provided are a method for producing sodium tungstate by supplying an oxidant made of sodium nitrate or sodium nitrite to bring a tungsten containing material and the oxidant into contact with each other in an atmosphere containing oxygen to thereby continuously produce a reaction product; a method for collecting tungsten using the method; and an apparatus for producing sodium tungstate. Also provided are a method for producing a sodium tungstate aqueous solution in which a reductant is introduced into a melt containing the above-described reaction product which is then dissolved in water; and a method for collecting tungsten using the method.

Abstract: Provided are a method for producing sodium tungstate by supplying an oxidant made of sodium nitrate or sodium nitrite to bring a tungsten containing material and the oxidant into contact with each other in an atmosphere containing oxygen to thereby continuously produce a reaction product; a method for collecting tungsten using the method; and an apparatus for producing sodium tungstate. Also provided are a method for producing a sodium tungstate aqueous solution in which a reductant is introduced into a melt containing the above-described reaction product which is then dissolved in water; and a method for collecting tungsten using the method.

Abstract: Provided are a method for producing sodium tungstate by supplying an oxidant made of sodium nitrate or sodium nitrite to bring a tungsten containing material and the oxidant into contact with each other in an atmosphere containing oxygen to thereby continuously produce a reaction product; a method for collecting tungsten using the method; and an apparatus for producing sodium tungstate. Also provided are a method for producing a sodium tungstate aqueous solution in which a reductant is introduced into a melt containing the above-described reaction product which is then dissolved in water; and a method for collecting tungsten using the method.

Abstract: A method for producing an ammonium tungstate aqueous solution includes the steps of: adding sulfuric acid to a solution containing tungstate ions; bringing the solution having the sulfuric acid added therein, into contact with an anion exchange resin; and bringing the anion exchange resin into contact with an aqueous solution containing ammonium ions.

Abstract: There are provided a cemented carbide high in thermal diffusivity and excellent in wear resistance, and a cutting tool including a base material formed of this cemented carbide. The cemented carbide is a WC based cemented carbide in which a hard phase mainly constituted of WC grains is bound by a binder phase mainly constituted of Co, and is used for a cutting tool. The binder phase is substantially constituted of Co, or Co and Ni. A total content of Co and Ni is not less than 4.5 mass % and not more than 15 mass %. In this cemented carbide, the WC grains have an average diameter of not less than 0.4 ?m and not more than 4 ?m.

Abstract: Provided are a method for producing sodium tungstate by supplying an oxidant made of sodium nitrate or sodium nitrite to bring a tungsten containing material and the oxidant into contact with each other in an atmosphere containing oxygen to thereby continuously produce a reaction product; a method for collecting tungsten using the method; and an apparatus for producing sodium tungstate. Also provided are a method for producing a sodium tungstate aqueous solution in which a reductant is introduced into a melt containing the above-described reaction product which is then dissolved in water; and a method for collecting tungsten using the method.