Study On Preparation Of High-pure And Ultra-fine Aluminum Hydroxide

In the paper, the aluminum hydroxide gel was prepared by direct precipitation method, and then the gel was purified through aluminum-type mixed resin to obtain the high-pure and ultra-fine aluminum hydroxide powder. The conditions were optimized to confirm the effects of the process conditions of purifying gel on the morphology and purity of product. The structure, morphology and purity of product were characterized by XRD, SEM, EDX, FTIR.The optimum technical parameters of purifying gel by mixed resins were confirmed: pneumatic stirring time is 4h and proportion of anion and cation exchange resins is 2:1. The lowest conductivity of as-prepared gel is 1.0μs/cm ,and the morphology of product is symmetrical triangle.The treating method of regenerated liquids and the water saving technology of washing resins were confirmed: the anion and cation exchange resins are washed respectively by deionized water to the conductivities of 3300μs/cm and 6000μs/cm,and then above two resins are mixed in 1:2 to take off the salts of gel.It was confirmed by IR pattern that there are vibrating peaks of carbon-carbon double bond and polysubstituted benzene ring on the surface of aluminum hydroxide. The organic groups are linked on the powder to bring steric hindrance between particles, which has effective action to the dispersion of powder. It was confirmed by XRD pattern that the activating way of pneumatic agitation has great change to crystal model of aluminum hydroxide powder.The resins and purified gel were separated by gas floatation method, and it was confirmed that the pressure of gas-liquid blending pump is 0.5MP, and aluminum hydroxide powder with good dispersion and uniform strip shape was obtained.The aluminum hydroxide powder was prepared by aluminum-type mixed resin to treat aluminum hydroxide gel that was prepared by direct precipitation method, and the purity of powder was higher and the dispersion performance was better, in addition there was much surface-modificative aluminum hydroxide powder, which realized one-step finish of purification, dispersion, modification of powder and solved the problem that was difficult to wash off the soluble ions in direct precipitation method and reduced the wastage of water and the cost of preparation.