On behaviour of sodium and potassium impurities at ammonium paratungstate fabrication

A study was made on sodium and potassium distribution at ammonium paratungstate fabrication from solutions formed during the leaching of sintering products of tungstate concentrate with water taken in surplus against its stoichiometric quantity. It was established that during the evaporation of (NH4)2WO4 solutions the major sodium mass remained in mother liquor and only 2-5% of it deposited with ammonium paratungstate. Much more amount of potassium impurity -60-70% of its content in ammonium paratungstate solution - turned into ammonium paratungstate deposit. The decrease of sodium and potassium content is possible at the stage of CaWO4 deposition, which must be rinsed by water containing no alkali metal