Abstract:
Zircon is dissociated in a direct arc plasma to a chemically reactive form called Plasma Dissociated Zircon, which is dissolved in HF. Distillation of the mother liquor is controlled on the basis of the prevention of the formation of possibly Zr2F 12 polymeric groups. The degree of evaporation affects the purity of the zirconium fluoride crystals that are formed. These crystals are used in preparing fluorozirconate chemicals such as K 2ZrF 6 and (NH4 ) 2ZrF 6 • Further purifying can be done by recrystallisation in a water solution. Other zirconium chemicals can be prepared by breaking the stable zirconium-fluoride bond by precipitating and suspending the crystals in alkaline solutions. Fluoride-free zirconium chemicals can then be prepared by dissolving the precipitate in the corresponding mineral acid. High purity zirconium chemicals like K2ZrF 6, (NH4) 2ZrF 6, H2Zr0(S04) 2 .3H20 and Zr0Cl2.8H20 can be prepared in this way. During the fluoride recovery process, high value silica, that can be used as a filler in the rubber industry is prepared from H2SiF 6 solutions. Fluoride recovery is done by preparing aluminium fluoride from ammonium fluoride solutions. The properties of the aluminium fluoride are determined by the phase of the alumina used as starting material.
