USE OF FLUORSPAR IN WATER FLUORIDATION

This paper describes work aimed at investigating the physico-chemical factors influencing the fluorspar dissolution kinetics, with the objec tive of evaluating the feasibility of fluorspar as a source of water f luoridation. Experimental results indicated that under optimum conditi ons effluent fluoride concentrations well above 2 mg/L were obtained. However, fluoride concentrations can be reduced to below practical lev els at temperatures less than 20 degrees C and hardness greater than 1 00 mg/L as CaCO3. By treating fluorspar as a blend of CaF2 and CaCO3, the kinetic characteristics of fluorspar dissolution were accurately d escribed by a steady-state mass-transfer model. Basic operating parame ters for continuous fluoridation using a natural fluorspar-packed bed were investigated and the optimum conditions established. This study d emonstrated that water fluoridation with natural mineral fluorspar can be more practical for small communities located in warm climates with soft-water sources.