Sodium Tungstate Simple Preparation Process

odium tungstate is a chemical that is soluble in water, sparingly soluble in hydrogen but insoluble in ethanol, and glossy, lamellar or crystalline powders. Preparation of sodium tungstate is mainly divided into three categories, as follows:

1. Tungsten ore alkali solution Wollaston crushed to 320 mesh, and 30% caustic added to the reactor for alkaline hydrolysis. After alkali hydrolysis and calcium chloride synthesis of calcium tungstate. Calcium tungstate reacts with hydrochloric acid to form tungstic acid, which reacts with caustic soda to form sodium tungstate. Crystallization by evaporation, centrifugal dehydration, drying, that is sodium tungstate finished.

2. In the industrial production of sodium tungstate process is mainly raw material minerals such as wolframite with sodium hydroxide aqueous solution extraction, made crude sodium tungstate. The crude product is then acidified to an aqueous solution of tungstic acid, which is then made into tungstic acid again with sodium hydroxide. Refining method can be recrystallized with water. For a purer product, the aqueous solution may be added to hot concentrated hydrochloric acid to precipitate a precipitate of tungsten oxide monohydrate WO3 · H2O. The precipitate was washed repeatedly, then dissolved in aqueous sodium hydroxide and allowed to crystallize. Available at 6 ℃ dehydrate, and more than 6 ℃ in the dehydrate.

3. Sodium tungstate in the experimental preparation is mainly the excess of tungstic acid added to 20% sodium hydroxide solution. Stir under heating 4h. Then heat 30 ~ 40 ℃, and keep stirring. After the reaction is complete, filtered and the filtrate is concentrated by heating until crystallization occurs. With ice cooling, centrifugal dehydration, drying, the reagent sodium tungstate. Evaporation of mother liquor can recover low purity sodium tungstate reagent.

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