Process for reclaiming rare earth oxysulfide phosphor material

Details Process for reclaiming rare earth oxysulfide phosphor material Process for reclaiming rare earth oxysulfide phosphor material

1974-11-21

1976-05-04

Cooper, Jack

Compositions

Inorganic luminescent compositions

Compositions containing halogen; e.g., halides and oxyhalides

423 21, C09K 1146

Patent

active

039546578

ABSTRACT:
This disclosure depicts a process for reclaiming from contaminated color cathode ray tube screening waste rare earth oxysulfide phosphors, especially the red-emitting phosphor yttrium oxysulfide. The screening waste from which the phosphor material is to be reclaimed may contain, in addition to the phosphor material contaminants such as hardened photoresist material, blue-emitting and green-emitting zinc sulfide type phosphor materials and graphite. The novel phosphor reclaim process disclosed is characterized by having steps including subjecting the partially purified oxysulfide phosphor material to a wash in dilute nitric, acetic, hydrochloric or citric acid, preferably citric acid, in order to enhance the adherability of the reclaimed phosphor material during subsequent rescreening thereof. The phosphor material is subjected to a wash with sodium tri-polyphosphate to minimize during rescreening of the phosphor material cross-contamination of underlying blue-emitting or green-emitting phosphor materials. In accordance with another aspect of the disclosed reclaim process, graphite contaminants are separated from the phosphor material being reclaimed by suspending the graphite-contaminated phosphor material in an aqueous bath, adding tri-polyphosphate to the bath to cause the phosphor material to settle and then decanting the still suspended graphite.

REFERENCES:
patent: 3523904 (1970-08-01), Single
patent: 3625659 (1971-12-01), Hammond et al.
patent: 3740342 (1973-06-01), Platt et al.
patent: 3763050 (1973-10-01), Dikhoff et al.

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