The High Concentration Of Sodium Tungstate Solution Ion Exchange

Although the tradional strong basic type ion exchange process in tungstate hydrometallurgical process has been widely used, certain defacts of the process still existed, such as low cocentration of exchange solution (<25gWO3/L), low operating exchange capacity of the resin (240～260mgWO3/g(dry resin)), vast wastewater emmision, great comsumption of materials, high tungsten loss and so on. To overcome these deficiencies, this paper proposed a weak basic ion exchange process dealing with the tungstate solution with the concentration higher than 150gWO3/L. The study mainly includes:1) By comparing the properties of three resins(D301, D314, D363), the appropriate macroporous weak basic anion exchange resin D301 was choosen.2) The effects of the experiemental parameters such as solution pH, ammonia amount, and ammonia concentration were investigated. The experimental results showed that the D301 resin behaviorred quite well in the tungstate solution with the range of solution pH ranging 2.5～6.5, the concentration of solution ranging 150～350gWO3/L at room temperature. The exchange capacity of the D301 resin could reach over 850mgWO3/g dry resin. The results also showed that the stirring rate and solution concentration had little effect on the adsorption capacity. In desorption part, when the ammonia excess coefficient being 1.2～1.3, and the ammonia range being 20-40gNH3/L, D301 had rather well desorption behavior.3) The adsorption thermodynamics and desorption kinetics were discussed roughly. The results showed that the adsorption behavior could be described by the Freundlich model through fitting asorption isotherm equation. The kinetics study showed that the asorption rate of the resin was very quickly, which was conducive to inprove the efficiency of the process. The kinetics fitting results indicated that the Moving-Boundary Model could be used to describe the desorption kinetics.And the grain diffusion was the controlling step.4) The flow-sheet of weak basic anion exchange technique was designed and validated by using D301 resin to treat high solution (370gWO3/L) of industrial feed solution.