Phase Formation Processes in Natural Magnesium Silicates of Various Structures by Ammonium Fluoride Treatment

The processes of forsterite, enstatite, and talc treatment by ammonium fluoride have been studied. The phase-formation processes occurring during firing of fluorinated minerals were studied. It was established that structural silica of the minerals reacts with ammonium hydrogen difluoride with the formation of ammonium hexafluorosilicate, sublimation of which leads to removal of structural silica from the minerals with partial destruction of their structure. The firing of fluorinated minerals leads to their structural transformation with formation of magnesium nesosilicates and fluoronesosilicates.