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US 3,951,734 AGranted
Ammonia-ketone pulping process
AssigneeWeyerhaeuser Company
InventorsGerrit G. DeHaas, Charles J. Lang
Life of this patent
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Abstract
A method of employing the combination of ammonia and ketones as the cooking chemicals in a digester of a pulping process. This method results in a pulp which has a higher yield than the kraft process yet is characterized by kraft's high strength and fair bleachability. The spent liquor extracts are primarily lignin and contain little cellulose and hemi-cellulose.
Claims6
A pulping process comprising the steps of:
- mixing cellulosic raw materials with an aqueous pulping liquor containing ammonia and one or more ketones;
- digesting said cellulosic raw material in said liquor at a temperature of 170.degree.C to 220.degree.C and for a time of from 10 to 300 minutes with the ratio of 2 to 20 pounds pulping liquor to 1 pound oven-dried cellulosic raw material, the ammonia concentration and the ketone concentration being from 5 to 22% and 15 to 70% by weight, respectively, of the total liquor;
- cooling the mixture;
- separating the pulping liquor from the digested cellulosic raw material.
1 more element
A pulping process comprising digesting cellulosic raw material with an aqueous pulping liquor containing 10-22 weight % ammonia and 20-60 weight % ketone.
Dependencies are inferred from the claim text.