Process for reclaiming rare-earth metallic oxide and/or rare-earth metallic oxysulfide phosphors

US4473488A · kind A · utility

Assignee

• International Standard Electric Corporation · US

Inventors

• Heinz Beckerle · Esslingen am Neckar, DE
• Volker Gerstle · Lorsch, DE
• Gerhard Mauz · Köngen, DE

Key dates

• Filing date: Oct 6, 1982
• Grant date: Sep 25, 1984
• Expiry date: Oct 6, 2002

Classification

• Technology area (CPC Y): Emerging Cross-Sectional Technologies
• CPC primary: Y02W30/50
• WIPO field: Basic materials chemistry
• WIPO sector: Chemistry

Abstract

To a suspension of rare-earth phosphors and sulfidic or selenidic phosphors there is added about 1 to 2% of the amount of hypohalogenite which would be necessary to convert the entire sulfidic or selenidic chalcogenide phosphor into a soluble sulfate and/or selenate. When acidifying the dispersion to which hypohalgenite has been added, to a pH value of preferably between 1.5 and 2, a sedimentation of elementary sulphur and/or selenium forms and becomes attached to the sulfidic and/or selenidic phosphor solids, thus causing these phosphor solids to form sediment. The supernatant suspension containing the rare-earth phosphor is then decanted, and the rare-earth phosphor is reclaimed from the suspension. The disclosed reclaiming process is particularly suitable for decontaminating phosphor mixtures for use in manufacturing color television cathode-ray tubes.