Recovery of fibers from a fiber processing waste sludge

Abstract

A process of recovering a useful population of fibers and fines from the waste stream of fiber processing facility is disclosed. Steam explosion of the fiber-containing waste stream is used to increase the separation efficiency of the fibers from the ash. The steam explosion also enhances the quality of the recovered fibers and fines, providing a population of recovered fibers which can be incorporated into the fiber component of a tissue or absorbent paper product.

What is claimed is:  
     
         1 . A process of recovering fibers from waste paper recycling sludge comprising: 
 providing a waste sludge stream comprising a plurality of fibers and fines;    placing said waste sludge in a first vessel;    bringing an interior of said vessel and said waste sludge to an elevated temperature and pressure;    maintaining said elevated temperature and pressure for an effective time interval;    discharging said waste sludge from said first vessel to a second vessel, said second vessel being sufficiently vented to maintain a pressure drop during said discharge step, and to thereby provide a treated sludge product comprising treated fibers and fines;    passing said treated sludge through a separator to separate and collect a portion of said treated fibers and said treated fines from said sludge.    
     
     
         2 . The process according to  claim 1 , wherein said elevated temperature is within the range of about 130° C. to about 250° C.  
     
     
         3 . The process according to  claim 1 , wherein said effective time interval is between about 0.5 minutes to about 30 minutes.  
     
     
         4 . The process according to  claim 1 , wherein said elevated pressure is about 100 to about 300 psi.  
     
     
         5 . A process of converting waste fibers from a fiber process waste stream to a recoverable fiber having improved fiber properties comprising: 
 providing a waste stream comprising a mixture of fibers and ash from a fiber processing facility;    exposing said waste stream to an elevated temperature and pressure;    releasing rapidly said pressure from said waste stream, thereby providing a plurality of treated fibers within a treated waste stream; and    separating said treated fibers from said waste stream.    
     
     
         6 . The product according to the process of  claim 5  wherein said mixture of fibers further comprises a plurality of fines.  
     
     
         7 . The process according to  claim 5  wherein said elevated temperature is within the range of about 130° C. to about 250° C.  
     
     
         8 . The process according to  claim 5  wherein said elevated pressure is about 100 to about 300 psi.  
     
     
         9 . The process according to  claim 5  wherein said waste stream is from a waste paper recycling operation.  
     
     
         10 . The process according to  claim 5  wherein said waste stream is from a paper making operation.  
     
     
         11 . A process of converting waste fibers from a fiber process waste stream of a paper making facility to a recoverable fiber having improved fiber properties comprising: 
 providing a waste stream from a papermaking facility comprising a mixture of a plurality of fibers and ash;    exposing said waste stream to an elevated temperature and pressure;    releasing rapidly said pressure from said waste stream, thereby providing a plurality of treated fibers within a treated waste stream; and    separating said treated fibers from said waste stream.    
     
     
         12 . A process of improving the useful properties of fibers comprising: 
 providing a first supply of fibers, said fibers contained within a portion of a waste stream from a paper fiber processing operation;    subjecting said fibers in said waste stream to an elevated temperature;    discharging said fibers and said waste stream from a first pressure environment to a second pressure environment, said first pressure being greater than said second pressure;    separating a portion of said fibers from said waste stream, thereby providing a second supply of fibers, said second supply of fibers having improved fiber qualities than untreated fibers.    
     
     
         13 . The process according to  claim 12  wherein said portion of a waste stream further comprises a first supply of fines.  
     
     
         14 . The process according to  claim 13  wherein said separating step further comprises separating a supply of treated fines from said treated waste stream.  
     
     
         15 . The process according to  claim 14  wherein said supply of fines have improved fiber properties for paper product usage than said first supply of fines.  
     
     
         16 . The process according to  claim 12  wherein said waste stream further comprises a waste stream from a paper recycling facility.  
     
     
         17 . The process according to  claim 11  wherein said separated treated fibers are reintroduced into a paper making process stream.  
     
     
         18 . The process according to  claim 12  wherein said waste stream is from a waste paper recycling operation.  
     
     
         19 . The process according to  claim 12  wherein said waste stream is from a paper making operation.  
     
     
         20 . A modified cellulosic fiber that is prepared by a process comprising steam explosion of fibers contained within a fiber processing waste stream, said steam explosion occurring at a pressure at super-atmosphere and at a temperature range of about 130° C. to about 250° C. to give a modified cellulosic fiber having an altered morphology which increases the separation efficiency of the modified fiber from the waste stream.  
     
     
         21 . The modified fiber of  claim 20  wherein the modified fiber is in the form of a fine.  
     
     
         22 . The modified fiber of  claim 20  wherein said altered morphology includes a curl index greater than a curl index of fibers within said unmodified waste stream.  
     
     
         23 . An absorbent structure comprising modified cellulosic fibers according to the process of  claim 20 .  
     
     
         24 . An absorbent structure comprising treated fibers according to the process of claim  5 .