Synthesis of fluorophlogopite using solid-state reaction techniques

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Virginia Tech

A commercial solid-state batch process for the manufacturing of synthetic fluorophlogopite (KMg3A1Si3010F2) mica powder was evaluated and standardized. The minimum firing temperature and time for this process was determined to be 1000°C for 10 hours to both ensure the complete reaction of the raw materials and to limit the decomposition of the mica into secondary phases that occurs during overfiring. The addition of an excess amount of the fluoride K2SiF 6 to compensate for the loss of fluorine that occurs during firing was found to increase the formation of fluorophlogopite. Additionally, enclosing the material within closed containers also limits the loss of fluorine from the batch. The practice of pressing the raw material blend into cakes before firing was found to have no effect on the formation of fluorophlogopite and is, therefore, an unnecessary processing step. Finally, a quality control testing procedure that will be used in industry was developed to determine the amount of mica formed during a given heat.