Recovering excess vanadate phosphor removed from a cathodoluminescent screen

Claim 1

IN THE MANUFACTURE OF A CATHODE RAY TUBE HAVING A PHOSPHOR SCREEN EMPLOYING A RED-EMITTING PHOSPHOR COMPRISING A HOST CRYSTAL OF A VANADATEOF A TRIVALENT METAL SELECTED FROM THE GROUP CONSISTING OF YTTRIUM, GADOLINIUM AND LUTETIUM ACTIVATED BY A TRIVALENT RARE EARTH ELEMENT SELECTED FROM THE GROUP CONSISTING OF EUROPIUM AND SAMARIUM, A BLUE-EMITTING PHOSPHOR COMPRISING SILVER ACTIVATED ZINC SULFIDE, AND A GREEN-EMITTING PHOSPHOR COMPRISING SILVER ACTIVATED ZINC-CADMIUM SULFIDE, SAID RED, BLUE AND GREEN-EMITTING PHOSPHORS BEING MIXED WITH POLYVINYL ALCOHOL, THE METHOF OF RECOVERING SAID RED-EMITTING PHOSPHOR FROM SAID BLUE AND GREEN-EMITTING SULFIDE PHOSPHORS COMPRISING THE STEPS OF (A) REMOVING EXCESS RED, BLUE, AND GREEN PHOSPHORS AND POLYVINYL ALCOHOL FROM THE SCREEN TO FORM A MIXTURE, (B) SEPARATING THE SOLID PORTION OF SAID MXITURE OF PHOSPHOR AND POLYVINYL ALCOHOL FROM THE REST OF SAID MIXTURE, (C) HEATING SAID SOLID PORTION TO APPROXIMATELY 450* C. FOR ABOUT ONE HOUR UNTIL SUBSTANTIALLY ALL OF SAID POLYVINYL ALCOHOL IS REMOVED, (D) TREATING THE REMAINING MIXTURE WITH A HOT DILUTE MINERAL ACID THEREBY SELECTIVELY DISSOLVING SAID BLUEEMITTING AND GREEN-EMITTING PHOSPHORS WHILE BEING SUBSTANTIALLY NON-RECEIVE WITH SAID RED-EMITTING PHOSPHOR, AND (E) DRYING THE RECOVERED RED-EMITTING PHOSPHOR, SAID RECOVERED RED-EMITTING PHOSPHOR HAVING ESSENTIALLY THE SAME LUMINESCENT PROPERTIES AS THE ORGINIAL COMPOSITION.