Very low COD unbleached pulp

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 2.0 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 220 minutes at an elevated temperature to produce the pulp product that has a low COD.

The embodiments of the invention in which an exclusive property or privilege is claimed are defined as follows:  
     
         1 . A pulp product, comprising unbleached pulp, wherein the pulp product has a COD that is less than or equal to 2.0 kg per 1000 kg dry pulp.  
     
     
         2 . The product of  claim 1 , wherein the pulp product has a COD that is less than 1.8 kg per 1000 kg dry pulp  
     
     
         3 . The product of  claim 1 , wherein said pulp is repetitively soaked and washed for at least 220 minutes at an elevated temperature.  
     
     
         4 . The product of  claim 3 , wherein said pulp is maintained at a temperature of at least 70° C. for at least a portion of said 220 minutes.  
     
     
         5 . The product of  claim 1 , wherein said pulp before washing has a Kappa number of ≦30.  
     
     
         6 . The product of  claim 1 , wherein said pulp after washing has a Kappa number of ≦30.  
     
     
         7 . The product of  claim 6 , wherein said pulp after washing has a Kappa number less than or equal to 25±3.  
     
     
         8 . The product of  claim 1 , wherein the pulp is comprised of Southern Pine pulp.  
     
     
         9 . The product of  claim 1 , wherein the pulp is comprised of Douglas Fir pulp.  
     
     
         10 . The product of  claim 1 , wherein the pulp is comprised of mini-chip pulp.  
     
     
         11 . The product of  claim 1 , wherein the pulp is soaked and washed in water that is always at alkaline conditions.  
     
     
         12 . The product of  claim 1 , wherein the pulp is a Kraft pulp.  
     
     
         13 . A cementitious product containing the pulp of any one of claims  1  through  12 .