Method And System For Dewatering And Controlling Foam In Pulp And Paper Processes

Abstract

Methods and systems are provided for dewatering an aqueous cellulosic pulp slurry or mat of cellulosic fibers or sludge. The method includes adding at least one anionic surfactant and at least one amide of a carboxylic acid to cellulose containing material to form a treated material and then dewatering the material. Besides effective dewatering, the present invention also provides foam control such as, but not limited to, the suppression of foam. Pulp products containing the treatment compounds are also described.

What is claimed is: 
     
         1 . A method for dewatering a cellulose-containing material, said method comprising:
 adding at least one anionic surfactant and at least one amide of a carboxylic acid to said cellulose-containing material to form a treated cellulose-containing material; and   dewatering said treated cellulose-containing material to provide a dewatered cellulose-containing material.   
     
     
         2 . The method of  claim 1 , wherein said cellulose-containing material is an aqueous cellulosic pulp slurry. 
     
     
         3 . The method of  claim 1 , wherein said cellulose-containing material is a mat of cellulosic fibers. 
     
     
         4 . The method of  claim 1 , wherein said cellulose-containing material is a sludge from a paper and pulp manufacturing process. 
     
     
         5 . The method of  claim 1 , wherein said anionic surfactant and said amide of a carboxylic acid are added together to said cellulose-containing material. 
     
     
         6 . The method of  claim 1 , wherein said anionic surfactant and said amide of a carboxylic acid are separately added to said cellulose-containing material. 
     
     
         7 . The method of  claim 1 , wherein the anionic surfactant is an organic anionic surfactant. 
     
     
         8 . The method of  claim 1 , wherein said amide of a carboxylic acid comprises a dimethylamide of a fatty acid. 
     
     
         9 . The method of  claim 1 , wherein said amide of a carboxylic acid comprises a dimethylamide of a fatty acid having 14 to 18 carbon atoms. 
     
     
         10 . The method of  claim 1 , wherein said cellulose-containing material is an aqueous cellulosic pulp slurry, and wherein said method further comprising bleaching the aqueous cellulosic pulp slurry after pulp forming and before the adding of the anionic surfactant and said amide of a carboxylic acid. 
     
     
         11 . The method of  claim 1 , wherein said cellulose-containing material is an aqueous cellulosic pulp slurry, and wherein said method further comprising thermally drying said cellulose-containing material that is dewatered to form market pulp. 
     
     
         12 . The method of  claim 1 , wherein the anionic surfactant is a sulfate surfactant, a sulfonate surfactant, a sulfosuccinate surfactant, or any combinations thereof. 
     
     
         13 . The method of  claim 1 , wherein the anionic surfactant is an alcohol sulfate, an alcohol alkoxy sulfate, a sulfonate, a dialkyl sulfosuccinate, a sulfosuccinic acid ester with an ethoxylated alcohol, or a soluble or dispersible salt thereof, or any combinations thereof. 
     
     
         14 . The method of  claim 1 , said method further comprising bleaching said cellulose-containing material before the adding of the at least one anionic surfactant and the at least one amide of a carboxylic acid. 
     
     
         15 . The method of  claim 1 , said method further comprising adding at least one enzyme to said cellulose-containing material before said dewatering step. 
     
     
         16 . The method of  claim 1 , wherein said amide of a carboxylic acid is added in an amount to control foam height during said dewatering. 
     
     
         17 . The method of  claim 1 , wherein the at least one anionic surfactant and the at least one amide of a carboxylic acid are added to the pulp in a weight ratio of from about 90:10 to about 10:90. 
     
     
         18 . The method of  claim 1 , wherein the anionic surfactant is added to the pulp in an amount of from about 0.1 lb./ton dry fiber to about 10 lb./ton dry fiber, and the amide of a carboxylic acid is added to the pulp in an amount of from about 0.001 lb./ton dry fiber to about 2 lb./ton dry fiber. 
     
     
         19 . The method of  claim 1 , wherein said cellulose-containing material is formed from hardwood chips, softwood chips, recycled paper fiber, or any combinations thereof. 
     
     
         20 . The method of  claim 1 , wherein the combination of treating the pulp with the at least one anionic surfactant and at least one amide of a carboxylic acid before said dewatering is effective to provide at least one of the following:
 (i) increased dewatering of a pulp slurry to a value which is at least 7.5% times greater than the amount of water removed obtained without any treatment in the pulp;   (ii) reduced foam height during said dewatering compared to foam height occurring with using the same anionic surfactant in the absence of said amide of a carboxylic acid.   
     
     
         21 . The method of  claim 1 , wherein said method is effective for increasing obtained water removal to a value which is at least five times greater than the water removal obtained without any treatment of the pulp. 
     
     
         22 . A dewatered cellulosic containing material dewatered by the method of  claim 1 , said dewatered cellulosic containing material comprising dewatered cellulosic containing material, said anionic surfactant and said amide of a carboxylic acid. 
     
     
         23 . The dewatered cellulosic containing material of  claim 22 , wherein said dewatered cellulosic containing material is dewatered pulp or dewatered sludge.