Solubility and Ionic Interaction of the CaF2–CaSO4–H2O System at 298.1 K

Solubility Phase Equilibrium of the Quaternary Reciprocal System Ca2+, Mn2+//F–, SO42– + H2O at 298.15 K

“…The solubility isotherms of the ternary systems of interest must be determined prior to the construction of the comprehensive phase diagram of the quaternary reciprocal system. Since the solubility isotherms for the ternary systems CaF 2 + CaSO 4 + H 2 O and CaSO 4 + MnSO 4 + H 2 O are known at 298.15 K, , the other ternary systems, namely, CaF 2 + MnSO 4 + H 2 O, MnF 2 + MnSO 4 + H 2 O, and CaF 2 + MnF 2 + H 2 O, and the quaternary systems, such as CaF 2 + CaSO 4 + MnSO 4 + H 2 O and CaF 2 + MnF 2 + MnSO 4 + H 2 O, will be determined in this work.…”

“…In this work, the solubility of CaF 2(s) in the reciprocal system Ca 2+ , Mn 2+ //F – , SO 4 2– + H 2 O and its subternary systems at 298.15 K has been elaborately determined by isothermal solid–liquid equilibrium measurements. Because the solubility isotherms for the ternary systems CaF 2 + CaSO 4 + H 2 O and CaSO 4 + MnSO 4 + H 2 O at 298.15 K have already been determined, , those at 298.15 K in other ternary systems, such as M + MnSO 4 + H 2 O (M = CaF 2 and MnF 2 ) and CaF 2 + MnF 2 + H 2 O, and quaternary systems, such as CaF 2 + N + MnSO 4 + H 2 O (N = MnF 2 and CaSO 4 ), will be investigated in the present work. The goal of this study is to provide fundamental solubility data for the process design of calcium and fluoride ion removal from MnSO 4 aqueous solutions.…”

Experimental Measurement of the Solid–Liquid Equilibrium of the Systems MF2 + H2O (M = Mg, Ca, Zn) from 298.15 to 353.15 K

“…The MgF 2 and CaF 2 concentrations in each saturated solution were analyzed by fluoride ion selective electrode (FISE, PF-1-01, INESA Scientific Instrument Co., Ltd.) as well as by titration with ethylenediamine tetraacetic acid disodium salt dihydrate (EDTA). The FISE analysis procedure was described in our previous work . On the basis of the reading precision ±1 of the FISE, one can evaluate that the relative uncertainty u r of the measured data is about 0.07.…”

“…Fluoride ions in the zinc hydrometallurgical system, when they are enriched to a certain concentration (say, more than 100 mg of F/L of solution), will harm the anode and cathode processes, and they need to be removed from the ZnSO 4 aqueous solution. It is well-known that CaF 2 and MgF 2 are sparingly soluble at 298.15 K. 1 If their solubility levels hold in ZnSO 4(aq) solution as in pure water, then calcium and magnesium ions in the solution should be effective substances to remove fluoride from the ZnSO 4(aq) solution. However, their solubility behavior in these systems is still unknown.…”

“…The FISE analysis procedure was described in our previous work. 1 On the basis of the reading precision ±1 of the FISE, one can evaluate that the relative uncertainty u r of the measured data is about 0.07. Meanwhile, the relative uncertainty u r of the data measured by EDTA titration can reach 0.01.…”