Method for Preparing Ultrafine Tungsten Trioxide

The invention relates to a method for preparing ultrafine tungsten trioxide, which comprises the steps of crystal seed preparation, material proportioning, hydrothermal reaction, separation by filtration, low-temperature roasting and the like. The invention has the advantages of short technical process, mild conditions and no need of complex equipment; the prepared tungsten trioxide has the advantages of high purity and small particle size; the mother solution can be recycled; and the utilization ratio of the sodium tungstate raw material is high.

A process for preparing ultrafine tungsten oxide, characterized by comprising the steps of:

(1) Preparation of seed: the preparation concentration of 10% ~ 52% of the sodium tungstate solution, with an organic acid or inorganic acid to adjust the solution pH to 4.0 - 8.0 range, in the hydrothermal autoclave for 4 to 15 hours, and the resulting precipitate was filtered, evaporation, crystallization, to obtain seed;

(2) Mole ratio of: the concentration of the preparation 10% to 55% solution of sodium tungstate, seed crystals are added to the solution, the seed crystal in the solution quality and the mass ratio of sodium tungstate in I: 2. 5 ~ I: 8. 5 range;

(3) High reaction: sodium tungstate solution with a seed crystal was placed on a stainless steel autoclave at 60 ~ 350 ° C reaction temperature and under strong stirring, stirring hydrothermal reaction, hydrothermal reaction for 4 to 20 hours After stirring was stopped, the autoclave was cooled to room temperature, taken out after one of the solid-liquid mixture;

4) It was isolated by filtration: the step (3) of the liquid mixture in the slurry was separated by filtration to obtain the tungsten trioxide fine cake and a mother liquor;

(5) Low-temperature firing: the fine tungsten trioxide cake was calcined in a baking furnace to obtain the low temperature of the tungsten trioxide fine product;

(6) The mother liquor was evaporated: the mother liquor and the washings were separated by filtration with heating evaporation stage , the concentration of sodium tungstate was prepared from 3% to 20% of the circulating liquor;

(7) Recycling the mother liquor: the loop back to the seed crystal mother liquor preparing step, for the preparation concentration of 5% to 45% of sodium tungstate water.




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