The alkaline feed of crude sodium tungstate obtained from the caustic fusion of black tungsten ore was neutralized to a pH value near 9 to eliminate Si as routine, then the resulting feed was directly used as the external aqueous phase without eliminating P, As and Mo.

Through a single stage batch liquid membrane process at room temperature for 5 min under optimum operation conditions obtained by an orthogonal test, ammonium paratungstate directly crystallizes in the internal aqueous phase with 99.87% yield and the quality attained was the first grade of a national standard; meanwhile the pH value of the effluents was lowered to 6–7 in itself suitable for direct discharge and without W (VI) lost out of the raffinate. Finally, a continuous counter-current process of a single stage for a pilot plant was proposed.




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The crystallization of ammonium paratungstate tetrahydrate, ((NH₄)₁₀OH₂W₁₂O₄₂·4H₂O, APT·4H₂O) from aqueous ammonium tungstate solutions is a key unit operation in current tungsten powder production. Ammonium paratungstate hexahydrate (APT·6H₂O) can form under conditions where APT·4H₂O forms as well. Based on this information it was postulated that APT·6H₂O is metastable. Experiments were carried out to determine whether and under what conditions the hexahydrate is metastable.

It was found that the hexahydrate is metastable at a solution concentration of approximately 300-230 g/kg WO₃ and from approximately 90° to 96°C. APT·6H₂O is not formed when APT·4H₂O seeds are added prior to crystallization. It was found that the recrystallization of APT·6H₂O into APT·4H₂O is prompted by a decreasing water activity in solution during crystallization. The increase in solution temperature during isobaric crystallization also stimulates the recrystallization process. In industrial practice some residual crystals are always present in the crystallizer. Therefore, APT·6H₂O will not form during industrial crystallization.



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Ammonium paratungstate (or APT) is a white crystalline salt of ammonium and tungsten, with the chemical formula (NH₄)₁₀(H₂W₁₂O₄₂)·4H₂O.

Method using ammonia tungstate tungstic acid dissolved, add a boil deionized water. In the stirring, heating by ammonia, Ph value is 8, in the boiling solution by adding acetic acid, and then use the dilute nitric acid. The Ph value is adjusted to 2 ~ 4, continuing heating concentrated to a relative density of 1.5 ~ 2, stop heating, cooling and filtering. The filtrate is added with ethanol. Stir, settlement after filtration, crystal at 80 ℃ drying, pulverizing to obtain the product.

Ammonium paratungstate is used as a source for high-purity tungsten oxides, tungsten metal powders, carbides, or as a laboratory reagent. Also tungsten powder including tungsten trioxide, tungsten blue oxide.




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Tungsten copper heat sink is a composite of tungsten and copper. The coefficient of thermal expansion (CTE) of the composite can be designed by controlling the content of tungsten, matching that of the materials, such as Ceramics (Al2O3, BeO), Semiconductors (Si), Metals (Kovar), etc. The products are widely application in the fields such as radio frequency, microwave, high power diode packaging and optical communication system.

Tungsten copper heat sink is a heat base which is made of tungsten copper alloy. A heat base is a term for a component or assembly that transfers heat generated within a solid material to a fluid medium, such as air or a liquid. Examples of heat bases are the heat exchangers used in refrigeration and air conditioning systems and the radiator (also a heat exchanger) in a car. Heat bases also help to cool electronic and optoelectronic devices, such as higher-power lasers and light emitting diodes (LEDs).

Advantages: High thermal conductivity, Excellent hermetic, Excellent size control, surface finish and flatness, Semi-finished or finished (Ni/Au plated) products available properties of WCu and MoCu heat materials.

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