Loading patent…
AssigneeMorton Thiokol, Inc.
InventorsThomas Joachimides, Stephen H. Levis, Bert A. Edstrom, Hans B. S. Moldenius
Estimating the term…
A paper pulp refining and bleaching process wherein the pulp is treated in one or more refiners with a sodium hydrosulfite bleach liquor in the presence of a strong alkali such as NaOH, whereby the bleaching solution has an alkaline pH, preferably 10 to 12, and the pulp is discharged from the refiner at a pH of from about 5 to 6. The bleaching produces a brightness gain of at least 8 to 13 ISO points in the refiners. The process is preferably carried out by passing the pulp successively through a primary refiner at elevated pressure, a secondary refiner at atmospheric pressure and a bleaching tower, an alkaline hydrosulfite solution being fed to each.
A process for simultaneously refining and bleaching wood pulp in a refiner to provide pulp of improved brightness comprising concurrently introducing bleach liquor and pulp or wood chips in one or more refiners including a primary pressurized refiner and wherein the bleach liquor comprises a solution of sodium hydrosulfite and sodium hydroxide, said solution having an alkaline pH of from about pH 10 to about pH 13 and wherein not more than about 2% by weight of sodium hydrosulfite, based on the total weight of the pulp or wood chips, is added, and the pulp is discharged from the refiner at a pH of from about 5 to 6 and whereby the bleaching produces a brightness gain of at least about 8 to 13 ISO points in the refiners.
A simultaneous wood pulp refining and bleaching process which comprises the steps of:
Dependencies are inferred from the claim text.