The researchers produce coarse spherical tungsten powder by ammonium paratungstate reduction using ammonium tungstate solution as a raw material, and adding additives containing Li, Na, and K alkali metal salts.
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Ammonium Paratungstate Reduction Producing Coarse Spherical Tungsten Powder
Add Li2CO3, NaCl or Li2CO3, NaCl and KCl to 1L of ammonium tungstate solution, stir quickly to make it completely dissolved to make mother liquor, crystallized at a temperature greater than 50 °C. Add the solution continuously during the crystallization process to satisfy the required grain size and control the powder particle size requirements. Dry the prepared ammonium paratungstate wet slurry in a far infrared oven at 80 °C for 10 h to obtain ammonium paratungstate powder. After grinding and crushing through a 60 mesh sieve, it is placed in a single-tube hydrogen furnace, and the reduction is carried out at a temperature of 1000 °C for 90 to 180 min. Tungsten powder obtained after reduction needs to be put into hydrochloric acid and deionized water, and ultrasonic wave is used for cleaning and washing until the solution is clarified, finally dried, grinded and sieved again, and the obtained tungsten powder is analyzed by energy spectrometer to determine alkali metal elements. If recorded in the allowable range, then pack the product, or to be re-cleaned.
