Two-step purifying solution for preparation high pure aluminium hydroxide

Aluminium hydroxide with 99.99% of purity was obtained by two-step purifying aluminium sulfate solution made from aluminium hydroxide and sulfuric acid with industry purity. The effects of the activated carbon and the ion exchange resins, and the effect of pH value in the presence of the shielding reagent on the purification were investigated. The results show that the chelate exchange resin Da is the best one for purification of solutions with 6 times of saturation exchange capacity in volume. In the presence of shielding reagent, 4.8% Fe~(3+) and 16.41% Fe~(3+) was co-precipitated in aluminium sulfate solution at pH 4.5 and 6.5 , respectively. In the absence of the shielding reagent, 80% Fe~(3+) is co-precipitated .The experiment results are in good agreement with the calculation results based on mass balance. Therefore the shielding reagent A is selected for the second purity step in the course of precipitation.