Effect of Silicate Matter on Pyrochlore Solubility in Fluoride Solutions at T= 550-850℃, P= 50-100 MPa (Experimental Studies)

摘要

The experimental results of natural pyrochlore behavior in KF solutions in the presence of quartz at 550-850 degrees C and 50-100 MPa are presented. It is shown that silicate matter (quartz) exerts a significant effect on pyrochlore solubility in aqueous solutions of fluorides of alkaline metals under hydrothermal conditions. This study of the fluid inclusions has revealed the occurrence of reactions of high-temperature hydrolysis of KF under the experimental conditions: KF + H2O = KOH + HF; in which case, the interaction with quartz SiO2 + 2KOH = K2SiO3 + H2O is followed by the formation of a silicate glass phase (an aqueous solution-melt). This phase of alkaline glass is a Nb concentrator (Nb2O5 up to 16 wt %). The coefficient of Nb distribution between the glass and the fluid is approximate to 500 (in favor of the glass). It is determined that the phase of the silicate solution-melt can serve as an effective concentrator of the ore component (Nb) at the last lowtemperature stages of crystallization of rare-metal granites.