Method for pre-processing and processing pulp

Abstract

the present invention provides a method for pre-processing and processing straw pulp and forming a byproduct suitable for animal consumption. The present invention also provides a paper product comprising straw pulp. According to the present invention, straw pulp is formed by steam exploding straw chips in the presence of either no caustic or a small amount of caustic.

What is claimed is:  
     
         1 . A method for pulping straw and forming a usable byproduct, comprising: 
 mixing straw chips with steam and water to form a mixture;    exposing the mixture to temperatures and pressures sufficient to significantly soften the straw chips to form straw pulp, lignins and hemicellulose when exposed to a rapid decrease in pressure;    passing the mixture through a press to separate a portion of lignins and hemicellulose from the straw pulp such that a usable byproduct of water, reacted lignins and hemicellulose is formed; and    passing the straw pulp through a defiberizer to form a usable straw pulp.    
     
     
         2 . The method of  claim 1 , wherein the straw chips are mixed with a caustic before the mixture of straw chips, steam and water is exposed to temperatures and pressures sufficient to significantly soften the straw chips to form straw pulp, lignins and hemicellulose in the mixture when exposed to a rapid decrease in pressure.  
     
     
         3 . The method of  claim 2 , wherein the caustic is present in the mixture in about less than two percent (2%) by weight based upon the dry straw chips.  
     
     
         4 . The method of  claim 3 , wherein the potassium hydroxide is present in the mixture in about less than one-half percent (0.5%) by weight based upon the dry straw chips.  
     
     
         5 . The method of  claim 2 , wherein the caustic comprises sodium hydroxide.  
     
     
         6 . The method of  claim 2 , wherein the caustic comprises potassium hydroxide.  
     
     
         7 . The method of  claim 1  wherein the mixture is exposed to temperatures and pressures sufficient to significantly softened the mixture when exposed to a rapid decrease in pressure for between about two and one half (2½) minutes to about eight (8) minutes.  
     
     
         8 . The method of  claim 1  wherein the straw chips are selected from the group comprising: 
 ryegrass;  
 wheat; and  
 a mixture of grain and cereal straws.  
 
     
     
         9 . The method of  claim 1  wherein at least about seventy percent (70%) by weight of the straw chips are formed into straw pulp.  
     
     
         10 . The method of  claim 1  wherein the pressures sufficient to significantly soften the straw chips when exposed to a rapid decrease in pressure from between about 140 psig and about 200 psig to about atmospheric pressure.  
     
     
         11 . The method of  claim 1 , wherein the straw chips are formed by chopping straw to form a mixture of straw chips, meal, ash and grit and screening said mixture to separate a substantial portion of the straw chips from the meal, ash and grit.  
     
     
         12 . The method of  claim 11 , wherein said separated meal, ash and grit is used as animal feed.  
     
     
         13 . The method of  claim 12 , wherein said separated meal, ash, and grit is mixed with the usable byproduct to form an animal feed.  
     
     
         14 . The method of  claim 1 , wherein the straw pulp has a Canadian Standard Freeness of between about 200 and about 600.  
     
     
         15 . A paper product made from wood pulp and straw pulp wherein the straw pulp is produced by mixing straw chips with steam and water to form a mixture of straw chips, steam and water; exposing said mixture to temperatures and pressures sufficient to significantly soften the straw chips into straw pulp when exposed to decreased pressures; separating a substantial portion of said straw pulp from said mixture, and refining said straw pulp.  
     
     
         16 . The paper product of  claim 15 , wherein a portion of the wood pulp is derived from processed post consumer waste.  
     
     
         17 . The paper product of  claim 15 , wherein said straw chips are formed by chopping straw to form a mixture of straw chips, meal, ash and grit and screening said mixture to separate a substantial portion of the straw chips from the meal, ash and grit.  
     
     
         18 . The paper product of  claim 15 , wherein said straw pulp has a Canadian Standard Freeness (CSF) of between about 200 and about 600 and an STFI between about 14 and about 21.