| 摘要 |
<p>PURPOSE:To recover a reusable phosphor, by adding hydrogen peroxide to an effluent mainly composed of a phosphor discharged from the step of forming a fluorescent surface, a polyvinyl alcohol, and a salt of dichromic acid, and adjusting the pH value with aq. ammonia. CONSTITUTION:In the step of forming a fluorescent surface for a color picture tube by making use of a phosphor slurry mainly composed of a phosphor, e.g., an Eu-activated rare-earth red phosphor, polyvinyl alcohol and a salt of dichromic acid, 0.1-1.0wt.%, based on the solid matter, of hydrogen peroxide is added to an effluent discharged from this step and the pH value of the effluent is then adjusted to 9-10 by adding ammonia thereto. This decomposes and removes solidified PVA remaining in the phosphor and enables the salt of dichromic acid to be converted into a salt of chromic acid which exhibits a lowered sensitizing activity, so that a phosphor which can be reused like a fresh phosphor can be recovered.</p> |
