Fine grain metal salt powders - from metal salts eg ammonium para-tungstenate by reduced press evapn of salt soln at low temp

摘要

Process comprises introducing a metal salt e.g. 5(NH4)2O.12 WO3. 5H2O soln. into an enclosure; sealing the enclosure1 evacuating air from the enclosure to lower the press; introducing a gas inert to the metal salt in an amt. insufficient to raise the press. in the enclosure to atmos. press.; lowering the temp. to a point at which the solvent freezes; and evaporating the solvent from the frozen soln. The salt powders may subsequently be reduced to metal powders fo the same particle size by standard methods.