| 摘要 |
<p>1506580 Filtering ZnO AVTEX FIBERS Inc 11 March 1975 [8 Nov 1974] 48552/74 Heading C1A The filtration characteristics of solids in neutralized waste liquors from a viscose process for manufacturing rayon filaments and which contains hydrated zinc oxide are improved by a process which comprises elevating the temperature of the neutralized waste liquor and then treating the waste liquor to recover filtrable solids including hydrated zinc oxide, characterized in that the temperature of the waste liquor is raised to at least 125‹ C. under an elevated pressure sufficient to prevent any substantial loss of the water in the waste liquor until the room temperature filtration characteristic (as defined) is increased by at least 50%. The waste liquor is preferably neutralized with lime, and the filtered zinc oxide is preferably converted to zinc sulphate solution by the action of aqueous sulphuric acid and recycled to the viscose process, preferably after removing iron by oxidation to ferric iron and adjusting the pH to precipitate ferric hydroxide.</p> |
