Mechanism of the Decomposition of Calcium Fluoride by Aluminum Salt under Mechanical Force and Controllable Preparation of Cryolite

This work designed an efficient recovery of fluorine resources from fluoride-containing solid waste (FCSW) using acid-free aluminum salt and mechanochemical activation coupling methods. First, FCSW was leached in the traditional acid-free aluminum salt system, and the effects of various factors on the leaching efficiency in the leaching process were investigated. The kinetics and mechanism of the leaching process were further studied. Then, FCSW was treated by using a coupled mechanical activation technique, and the leaching conditions were optimized. Under optimal conditions, the fluoride leaching efficiency reached 98.09%, significantly higher than that of traditional leaching (75.86%), with the improvement mainly attributed to the reduction in the particle size, increase in the specific surface area, and decrease in the activation energy. Notably, the resulting leachate can directly prepare cryolite with a purity of 95.88%. Additionally, the process proposed in this study yields significant economic benefits and is environmentally friendly. This work provides a new strategy for the efficient recovery of fluorine resources from FCSW and a strong guarantee for the development of the fluorine chemical industry.