PROCESS FOR REGENERATION OF PHOSPHOR BASED ON EUROPIUM YTTRIUM ACTIVATED OXYSULFIDE Russian patent published in 1997 - IPC

FIELD: application of red component onto three-color kinescope screen. SUBSTANCE: red phosphor waste is treated with ammonium persulfate in acetic acid in the presence of hydrofluoric acid and the whole is stirred. After settling, the liquid phase is decanted, precipitate is poured with water, chloric lime is added in alkaline medium in amount from 10 to 20% by weight of phosphor under stirring. After settling, the liquid phase is washed 5 or 6 times with deionized water with addition of citric acid during last washing operation in amount of 0.2-0.3% by weight of phosphor and ammonium carbonate. Liquid phase is decanted, precipitate is dried at temperature of not higher than 130 C. Brightness of the regenerated phosphor is at least 101 relative units, color coordinates x=0.638-647 and y=0.338-3.47. The phosphor is free from admixtures of blue and green phosphors, and free yttrium content is 0.012-0.018 wt.-%. EFFECT: more efficient regeneration process. 1 tbl