Process for producing very low COD unbleached pulp
AssigneeWeyehaeuser Company
InventorsMichael D. Vrbanac, Brian Wester, Brian E. Dennis, Peter K. Lau, Julie A. Reimer, David W. Bickell
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Abstract
A pulp product that has a low COD is comprised of an unbleached pulp that is soaked and washed in alkaline water for a sufficient time so that the COD after soaking and washing is less than or equal to 3.0 kg/1000 kg of dry pulp. The pulp is produced by repetitively soaking and washing an unbleached pulp in alkaline water that is never allowed to drop below pH 7.0. The pulp is soaked and washed for a total of at least 400 minutes at an elevated temperature to produce the pulp product that has a low COD.
Claims13
A process for making a low COD pulp, comprising:
- (a) repetitively soaking and washing unbleached pulp containing sugars and other organic materials in water that is maintained at alkaline conditions such that said pulp is soaked for a total of at least 400 minutes at an elevated temperature to produce a pulp product having the sugars and other organic products reduced such that the pulp product has a COD of less than or equal to 3.0 kg per 1000 kg;
- (b) adding alkali to said pulp while soaking and washing;
- and
- (c) dewatering and drying said pulp while maintaining said alkaline conditions.
Dependencies are inferred from the claim text.