| 摘要 |
<p>MANGANIC ION BLEACHING PROCESS A process for delignifying lignocellulosic pulps, which comprises the steps of (a) impregnating a lignocellulosic pulp slurry with a water-soluble manganous salt having a manganous ion concentration of from about 1% to about 10%, by weight of ovendried pulp; (b) mixing the impregnated pulp slurry with sufficient alkali to precipitate the soluble manganous ion as insoluble manganous hydroxide; (c) contacting the pulp slurry with an oxygen-containing gas for a period of time sufficient to oxidize substantially all of the manganous hydroxide to manganic hydroxide; (d) treating the pulp slurry with sufficient acid to lower the slurry pH to at least about 3, thus releasing soluble manganic ions to oxidize the pulp lignins; (e) separating the effluent containing manganous ions from the pulp slurry with a non-alkaline wash; and then (f) extracting the oxidized lignins from the pulp slurry with an alkaline solution.</p> |
