Preparation of cryolite from simulated leaching solution of alkaline roasting of carbon dust
Recovery of fluorine from leachate by cryolite is the key step of harmless treatment and resource utilization of carbon dust. However,during the synthesis of cryolite,the competitive reaction of components such as sodium and aluminum is the main reason for the decrease of fluorine recovery in the leaching solution. For studying the reaction mechanism between cryolite and the main impurity,cryolite was prepared by NaF-NaAlO2 simulated solution to recover fluorine in the form of cryolite. The effects of the aluminum-fluorine molar ratio,pH value of the reaction endpoint and reaction temperature on the recovery fluoride efficiency were investigated. The results show that the synthesis of cryolite is easier in the advantageous range of fluoro-aluminum complex ions. With the aluminum-fluorine molar ratio of 1∶6,pH value of 8 and reaction temperature of 20℃,cryolite had good morphology,and the fluorine recovery rate in the solution reached 98.89％.
carbon dustfluorine recoverycryolitealuminum-fluorine molar ratio
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