Crystallization method of ammonium paratungstate

A technology of ammonium paratungstate and ammonium paratungstate, applied in the field of ammonium paratungstate crystallization, can solve the problems such as unseen research on ammonium paratungstate crystallization, inability to obtain large particles of ammonium paratungstate, uneven distribution, etc., to achieve coarse particles, controllable particle size, simple and easy process Effect

Inactive Publication Date: 2008-05-21
JINDUICHENG MOLYBDENUM CO LTD
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  • Summary
  • Abstract
  • Description
  • Claims
  • Application Information

AI Technical Summary

Problems solved by technology

Scholars at home and abroad have used adding seeds or ammonium tungstate solution (NH 4 ) 2 WO 4 Methods Some experiments were carried out: by adding seed crystal method, large particles of ammonium paratungstate could be obtained, but the distribution was uneven and the crystal morphology was poor;

Method used

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Examples

Experimental program
Comparison scheme
Effect test

Example Embodiment

[0012] Example 1

[0013] Formulated density 1.25g / cm 3 , Ammonium tungstate solution with a volume of 1.01 and a pH of 8.0 was added to a 3l three-necked flask and heated by an electric heating mantle. When the boiling reaches the supersaturated state, or there are tiny crystal grains, or the density reaches 1.38g / cm 3 At this time, 20 g of ammonium paratungstate seed crystals with a Fisher particle size of 30 μm were added to the solution. Maintain the temperature at 95°C, return to boiling state after 40 minutes, and then add dilute ammonia (pH 11) to adjust the pH of the ammonium tungstate solution to maintain the pH of the solution at 8.0. Evaporate to a mother liquor density of 1.08g / cm 3 At the same time, the material is discharged, filtered, washed with dilute ammonia water once, then washed with deionized water twice, and finally dried at 90°C.

[0014] The produced ammonium paratungstate product has a Fisher particle size of >45μm, a normal distribution, a good crystal s...

Example Embodiment

[0015] Example 2

[0016] Preparation density 1.28g / cm 3 , Ammonium tungstate solution with a volume of 1.01 and a pH of 8.5 was added to a 31 three-necked flask and heated by an electric heating mantle. When the boiling reaches the supersaturated state, or there are tiny crystal grains, or the density reaches 1.38g / cm 3 At this time, 10 g of ammonium paratungstate seed crystals with a Fisher particle size of 35 μm were added to the solution. Keep the temperature at 93°C, return to the boiling state after 30 minutes, and then add dilute ammonia (pH 12) to adjust the pH of the ammonium tungstate solution to maintain the pH of the solution at 8.5. Evaporate to mother liquor density of 1.10g / cm 3 Time, discharge, filter, wash 2 times with dilute ammonia water, wash 2 times with deionized water, and finally dry at 90°C.

[0017] The produced ammonium paratungstate product has a Fisher particle size of >45μm, a normal distribution, a good crystal shape and a smooth surface.

Example Embodiment

[0018] Example 3

[0019] Industrial production

[0020] (1) Change the density to 1.30g / cm 3 , Volume 3.5m 3 , Ammonium tungstate solution with pH 9.0, pump into the evaporation crystallization kettle;

[0021] (2) Start stirring, slowly open the steam valve, after the solution boils, adjust the steam valve to evaporate to boiling;

[0022] (3) When reaching the supersaturated state, or when there are tiny crystal grains, or the density reaches 1.38g / cm 3 Add 15kg of ammonium paratungstate seed crystals with a particle size of 40μm, and keep the solution temperature at 90℃ for 20min;

[0023] (4) Open the dilute ammonia pipeline of the upper tank, add ammonia water (pH 13) dropwise to the solution, and adjust the pH of the ammonium tungstate solution to 8.0;

[0024] (5) Evaporate to a mother liquor density of 1.09g / cm 3 When, discharging, filtering, washing with dilute ammonia water 2 times, and then washing with deionized water 3 times;

[0025] (6) Dry at 90°C.

[0026] The pr...

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Abstract

The invention discloses a crystallization method of ammonium paratungstate and relates to a production method of ammonium tungstate by adopting hydrometallurgy. The method is characterized in that the invention has a crystallization process that ammonium paratungstate crystal seeds are added into ammonium tungstate solution when the solution is evaporated and concentrated to appear microcrystalline particles for isothermal crystallization under the solution temperature of 90-95 DEG C for 20-40mins; the solution is then heated up to boil and added with weak aqua ammonia to adjust the pH value of the ammonium tungstate solution to 8.0-8.5 and then treated with feeding and filtering when the density of mother liquor reaches 10.8 to 1.10 g/cm <3>; the solution is again washed with the weak aqua ammonia and deionized water and dried to obtain the ammonium paratungstate crystals with large particle size and uniform distribution. The method of the invention effectively controls the crystallization of the ammonium paratungstate through the measures of removing fine crystals through the weak aqua ammonia, adding the crystal seeds, controlling the evaporation speed, etc.; in addition, the produced ammonium paratungstate crystals with large and controllable particle size are uniform and smooth; and the technology is simple and easy to be operated.

Description

technical field [0001] A method for crystallizing ammonium paratungstate relates to a method for producing ammonium tungstate by adopting a hydrometallurgical method. Background technique [0002] With the continuous development of new types of cemented carbide and tungsten wire for lamps, more and more stringent requirements are put forward for the chemical composition, Fischer particle size, particle size distribution and crystal morphology of ammonium paratungstate as raw material. Some users require The particles are fine, reaching the micron or even nanometer level; some users require coarse particles and perfect crystal morphology, and this patent mainly solves the latter problem. [0003] At present, the production methods of ammonium paratungstate mainly include neutralization method, evaporation method, ion exchange and extraction method. Evaporation method is often used in industrial production, but when preparing ammonium paratungstate by evaporation method, it is...

Claims

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Application Information

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IPC IPC(8): C01G41/00C01C1/00
Inventor 唐军利
Owner JINDUICHENG MOLYBDENUM CO LTD
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