Assessment of the possibility of application of some weakly basic anionites for conversion of sodium tungstate into ammonium tungstate

There was made a comparison of efficiency of application of anionites Lewatit MP62 and AM-2b (АМ-2б) and ampholyte VP-14K (ВП-14К) for conversion of sodium tungstate into ammonium tungstate. Tungsten capacity of anionite Lewatit MP62 is closed to ampholite VP-14K and is by ~1.5 times higher than the one of anionite AM-2b. Tungsten desorption from anionites Lewatit MP62 and AM-2b by ammonia solution at the room temperature is not complete. Increasing of temperature to 52–54 оС makes possible the significant improvement of results of tungsten desorption from both anionites: tungsten desorption completeness is considerably increased; eluent volumes, which should be passed through anionites, are decreased; and tungsten concentration in strippants is increased. Experiments with application of anionite Lewatit МР62 were carried out in dynamic conditions for the processing of sodium tungstate solution, obtained as a result of autoclave-soda leaching of tungsten from scheelite concentrate of one of concentration plants. Initial solution had the following composition, g/l: 62 of WO3, 102 of Na2CO3; 0.23 of Si; 3.36 of organic substances (assessment was carried out by the indicator of chemical oxygen uptake). After hydrolytic purification from silicon, solution was oxidized to the pH = 3.3, separated from the isolated organic substances and directed to the sorption into the column, fulled with anionite. Tungsten desorption was carried out by 14% solution of NH4OH at the temperature of 54 оС. During the sorption of tungsten from the industrial solution, tungsten capacity of anionite МР62 is not less high than during the sorption from model solutions (>300 mg of WO3/ml of anionite). Besides, there is confirmed the complete desorption of tungsten with hot ammonia solutions from anionite MP62. Concentration of WO3 in marketable desorbate was 78 g/l.