QUARTZ CLEANING METHOD Russian patent published in 2003 - IPC

FIELD: optical glass manufacture. SUBSTANCE: invention relates to methods for cleaning quartz stuff used for fusing of transparent quartz glass employed in optics, light engineering, electronics, and chemical engineering. Cleaning of quartz stuff is accomplished by its fractionation to grain ratio D_max/D_min = 2.8-6.0 followed by heat treatment at 1650-1700 C for 0.5-1.0 h, cooling, and grinding of resulting alphacristobalite to specified fineness, whereupon material undergoes additional heat treatment to temperature of transformation into beta-cristobalite, which is chemically treated, rinsed, and dried. For quartz with summary level of impurity elements higher than 51 ppm, cycle comprising additional heat treatment followed by chemical treatment, rinsing, and drying is repeated until constancy of summary level of impurities in enriched material. EFFECT: increased degree of purity of quartz stuff due to removal of substantial part of structural impurities. 2 cl, 1 tbl, 4 ex