Conversion of magnesium fluoride to magnesium hydroxide
10.1016/S0892-6875(03)00002-5
The research investigates the conversion of magnesium fluoride to magnesium hydroxide as part of a process to remove magnesium from zinc sulphate electrolyte in electrolytic zinc plants. The study aims to improve the conversion process to reduce the residual fluoride content in the magnesium hydroxide product, which is essential for its marketability. Experiments showed that optimizing operating conditions such as reaction temperature, stirring velocity, and leach concentration could not reduce the residual fluoride content to below 1 wt%. X-ray diffraction analysis indicated that the residual fluoride was incorporated into the brucite crystal structure. However, it was possible to reduce the fluoride content by calcining the magnesium hydroxide to magnesium oxide at temperatures above 1273 K, resulting in a saleable product with less than 1 wt% fluoride. The study concludes that while complete conversion to pure magnesium hydroxide is not feasible, thermal decomposition to magnesium oxide is a viable alternative for producing a marketable product.
Theoretical study of magnesium fluoride in aqueous solution
10.1021/jp2053647
This research is a theoretical study on the stability and solvation structure of magnesium fluoride (MgFn 2-n) complexes in both the gas phase and aqueous solution using the RISM-SCF-SEDD method. The study finds that in the gas phase, MgF3- is the most stable species among the complexes (n = 1–6), while in aqueous solution, the stability of various complexes is comparable due to the compensation between intramolecular energy and solvation free energy. The mole fraction of MgF4 2- is highest in the pF range of 2.0 to 3.0, which is consistent with available PDB data of enzymes catalyzing phosphoryl transfer reactions. The solvation structures reveal that the complexes form hydrogen bonds with surrounding water molecules, and the stability of the complexes is determined by a delicate balance between intramolecular interactions (Coulombic interactions between Mg-F and F-F) and intermolecular interactions with the solvent. The study highlights the importance of accurate free energy evaluation and careful consideration of solvation free energy, including hydrogen-bonding effects, to understand the behavior of these complexes in solution.
Compacted Magnesium Fluoride: Preparation, Characterization, and Optics
10.1134/S0036023619060081
A. F. Golota et al. investigate the electronic structure and optical properties of magnesium fluoride (MgF2) with a focus on the impact of defects. The study employs X-ray photoelectron spectroscopy (XPES) and other analytical techniques to explore how deviations from fluorine stoichiometry in MgF2–x result in a long-wavelength shift of the absorption edge. The authors find that defects in the fluorine sublattice cause coloration, reduced mechanical strength, and optical instability. They propose methods to reduce defectiveness, such as specific synthetic procedures and doping with a fluorine donor like fluoroaluminic acid (H3AlF6·6H2O). The modified MgF2, when heat-treated, shows improved properties, including a refractive index of 1.38–1.40, enhanced mechanical strength, and moisture stability for up to 28 days. The study concludes that the presence of structural oxygen in MgF2 leads to absorption centers in the visible and IR range, and that the decisive factor for material quality is the cation-to-anion ratio at the defect level rather than stoichiometric equilibrium.
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