Effect of Solution Supersaturation on Fluoride Removal from Fluidized Bed Crystallization
1. Changsha Environmental Protection College, Changsha 410004, China;
2. School of Metallurgy and Environment, Central South University, Changsha 410083, China
Abstract：To determine the treatment efficiency of the fluidized bed crystallization with different concentrations of fluorine-containing wastewater, the effects of supersaturation on fluorine removal and the growth rate of calcium fluoride crystals were investigated. The relationship between the supersaturation and the metastable zone of calcium fluoride crystals was explored. The results showed that the effluent fluorine concentration was less than 10 mg/L when the fluorine concentration was 100 mg/L in the wastewater and the solution supersaturation was 7.0. The precipitation conditions were close to the metastable zone of calcium fluoride, which favored the crystallization of the precipitates. The effluent fluoride concentration was between 20 mg/L to 40 mg/L at an influent fluoride concentration of 500 mg/L to 1 400 mg/L. The precipitation conditions were in the supersaturation zone of calcium fluoride and the linear growth rate of calcium fluoride was faster. However, the large amount of fine particles generated by homogeneous nucleation overflowed from the fluidized bed, resulting in an increase in the fluorine concentration and turbidity of the effluent. The fluoride removal process of the fluidized bed can be predicted based on the metastable zone of calcium fluoride and the solution supersaturation can be controlled to ensure the effect of precipitation and fluoride removal.
Jiang Ke 1,2,Zhou Kanggen 2. Effect of Solution Supersaturation on Fluoride Removal from Fluidized Bed Crystallization[J]. 化学反应工程与工艺, 2018, 34(2): 160-164.
