PROCESS FOR RECLAIMING RARE-EARTH METALLIC OXIDE AND/OR RARE-EARTH METALLIC OXYSULFIDE PHOSPHORS

摘要

Abstract of the DisclosureTo a suspension of rare-earth phosphors and sulfidic or selenidic phos-phors there is added about 1 to 2% of the amount of hypohalide which would benecessary to convert the entire sulfidic or selenidic chalcogenide phosphor intoa soluble sulfate and/or selenate. When acidifying the dispersion to which hypo-halide has been added, to a pH value of preferably between 1.5 and 2, there iscaused a sedimentation of elementary sulphur and/or selenium which becomes atta-ched to the sulfidic and/or selenidic phosphor solids, thus causing these phos-phor solids to sediment. The supernatant suspension containing the rare-earthphosphor is then decanted, and the rare-earth phosphor is reclaimed from the sus-pension. The disclosed reclaiming process is particularly suitable for decontam-inating phosphor mixtures as resulting in the course of manufacturing color tele-vision cathode-ray tubes.