When some form of acid treatment is required for the recovery of rare earth salvage as a usable phos phor, the phosphors of Class I are immediately eliminated as desirable red components. The remain ing phosphors, the vanadates and oxysulfides of yttrium and gadolinium (Class II), have comparable stability to acid treatment under selected process conditions. From an economic standpoint, the gado linium-based phosphors become impractical because of Gd2O5 raw material cost. Although this cost may be alleviated in the future, these phosphors offer no ad vantages over their yttrium counterparts. As a result, the yttrium-based phosphors of Class II are the most practical red components for color-television picture tubes at the present time. It is possible that a technique for the recovery of Class I phosphors as usable phosphors, which does not require acid treatment, could be devised. The lower conversion factors exhibited by these Class I phosphors make continual reclaim and reuse questionable. The reclaim of salvage of any rare earth phosphor is mandatory to justify its use. If a given rare earth phosphor, which cannot be reclaimed as a usable material, is found to possess certain desirable charac teristics, its use should not be discouraged on this factor alone. Any rare earth phosphor salvage can be reclaimed by recovering the rare earth raw materials by standard chemical means and synthesizing into new virgin phosphor. From an economic standpoint, such a reclaim procedure is more expensive than the direct recovery of salvage as usable material. A phosphor which cannot be directly reclaimed must have unusual merit in order to justify the added cost of complete reprocessing. © 1969, The Electrochemical Society, Inc. All rights reserved.
