Gte Products Corporation

Douglas M Jackson

John A Arbie, Sr

Richard G Gingerich

A method for making stir-in type halophosphate phosphors to obtain a fluffy, deagglomerated powder is disclosed. A wet phosphor filter cake is fed into a toroidal-shaped direct-fired glass flash dryer in which a hot gaseous stream is circulating. The wet phosphor particles are suspended in the stream while the remaining liquid is evaporated. The dried phosphor powder is ejected from the dryer by centrifugal force and collected. Recovery efficiency of the process is about 99.9 percent.

Deagglomerating direct-fired flash dryer for drying stir-in phosphors

A method is disclosed for producing alkaline earth halophosphate stir-in phosphors which comprises forming a mixture of about 55% to 75% calcium monohydrogen phosphate, about 15% to 35% calcium carbonate, about 2% to 20% ammonium chloride, about 1% to 15% manganese carbonate, about 1% to 15% antimony trioxide, and about 2% to 10% by weight calcium fluoride, wherein the average particle size of the calcium monohydrogen phosphate by Fisher subseive size is about 4.6 to 6.8 micrometers in diameter and the 50% Coulter Counter size is about 9.0 to 11.5, firing in a non-reacting atmosphere at 600.degree. C. to 1300.degree. C., milling in acid, wet screening through a first screen of greater than 300 mesh, removing the acid, suspending the material in water, screening through a second screen of greater than 350 mesh, adding base to form a slurry, removing the liquid phase from the slurried phosphor material, drying, transferring the material by vacuum to holding means, and transferring the material by gravity from the holding means to a vibratory feeder, transferring the material from the vibratory feeder by gravity to a third screen of greater than 350 mesh, and passing the material through the third screen wherein vacuum pulls the material to and through the screen and at the same time a flow of air behind the third screen results in vibration of the particles of the material as they pass through the third screen, and thereafter passing the particles under vacuum to collecting means.

Method for producing alkaline earth halophosphate stir-in phosphors

In the manufacture of an alkaline earth halophosphate phosphor, the phosphor ingredients are mixed, fired, wet milled and dried. By sieving the material part way through the wet milling process and by sifting the dry phosphor powder, the phosphor powder weight in fluorescent lamps can be reduced.

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Monroeton, PA, United States of America

Douglas M Jackson