High temperature peroxide bleaching of mechanical pulps
A method of making bleached mechanical pulps is disclosed for pulping mills having a primary and a secondary refiner. A first step (100) is to provide cellulosic materials such a wood chips to refine into the pulp; the wood chips have an initial brightness level. A second step (102) is to provide a...
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Zusammenfassung: | A method of making bleached mechanical pulps is disclosed for pulping mills having a primary and a secondary refiner. A first step (100) is to provide cellulosic materials such a wood chips to refine into the pulp; the wood chips have an initial brightness level. A second step (102) is to provide a bleaching liquor to the refining system of the pulp mill, wherein the liquor comprises an amount of hydrogen peroxide and an amount of alkali having greater than 0% to 100% magnesium hydroxide or soda ash or a combination thereof. A third step (104, 106) is to hold the pulp with the bleaching liquor at a temperature in the range of about 85o to about 160oC and for about 2 to 180 minutes. |
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