Abstract: In order to solve the problem of environmental pollution in the process of processing and utilization of fluorine resources,improve the comprehensive utilization rate of fluorine resources in fluorine-containing wastewater,the sedimentation behavior and particle size characteristics of calcium fluoride crystallization particles in fluorine-containing acidic wastewater were systematically studied,and the flotation characteristics of calcium fluoride crystallization particles were explored. Combined with the chemical precipitation formation process of calcium fluoride simulated by Visual MINTEQ software,the phase composition of crystallization particles was characterized by XRD,and the action mechanism between NaOL and calcium fluoride particles was analyzed by Zeta potential test. The results showed that when calcium chloride was used to treat fluorine-containing acidic wastewater,calcium fluoride crystallization particles could not be formed under strong acid conditions. When pH> 5,stable calcium fluoride crystallization precipitation products could be obtained. And the higher the concentration of F- in the wastewater,the more the number of crystallization particles,the larger the particle size. The obtained calcium fluoride crystallization had high purity and almost no other impurities. When the pH was 5~9,sodium oleate could be adsorbed on the surface of calcium fluoride crystallization particles,so that it had good floatability,and the dosage of sodium oleate was proportional to the concentration of F- in the wastewater,and the flotation recovery effect was good. The results of this study can provide a theoretical reference for the treatment of fluorine-containing wastewater and the recovery of calcium fluoride resources.

Key words: fluoride-containing acidic wastewater,calcium fluoride,crystallization behavior,floatability