Processes for paper manufacture, useful for incorporating paper waste requiring a basic treatment into paper products

Abstract

Processes for manufacturing a paper product from cellulose pulp, part of which comes from a broke and part of which comes from a fresh pulp are provided. The processes involve first redissolving in a broke pulper, with stirring and in an alkaline medium, cellulose fibers contained in said broke to form a broke pulp. Next, the broke pulp is brought to a concentration and a pH close to that characteristic of the fresh pulp by ( 1 ) diluting said broke pulp with a white water and ( 2 ) acidifying said broke pulp by injecting carbon dioxide into said broke pulp after the broke pulp has left the broke pulper and before admixing said broke pulp with said fresh pulp. Then the broke pulp is admixed with the fresh pulp to form a pulp mixture and the pulp mixture is dewatered to form a paper product and a white water.

What is claimed is:  
     
         1 . A process for manufacturing a paper product from cellulose pulp, part of which comes from a broke and part of which comes from a fresh pulp, said process comprising the steps of: 
 redissolving in a broke pulper, with stirring and in an alkaline medium, cellulose fibers contained in said broke to form a broke pulp,    bringing said broke pulp to a concentration and a pH close to that characteristic of the fresh pulp by (1) diluting said broke pulp with a white water and (2) acidifying said broke pulp by injecting carbon dioxide into said broke pulp after the broke pulp has left the broke pulper and before admixing said broke pulp with said fresh pulp;    admixing the broke pulp with the fresh pulp to form a pulp mixture; and    dewatering the pulp mixture to form a paper product and a white water.    
     
     
         2 . The process of  claim 1 , wherein said redissolving step is carried out in a broke pulper.  
     
     
         3 . The process of  claim 1 , wherein said admixing step is carried out in a mixing chest.  
     
     
         4 . The process of  claim 1 , wherein said dewatering step takes place in a paper making machine.  
     
     
         5 . The process according to  claim 1 , wherein said step of diluting said broke pulp with white water comprises at least two steps of dilution with white water.  
     
     
         6 . The process according to  claim 1 , comprising injecting the carbon dioxide into the white water serving for diluting the broke pulp.  
     
     
         7 . The process according to  claim 4 , comprising diluting said broke pulp with white water recovered from the paper machine.  
     
     
         8 . The process according to  claim 7 , comprising diluting said broke pulp with white water from sources other than said paper making machine.  
     
     
         9 . The process according to  claim 8 , wherein said sources other than said paper making machine comprise white water coming from preparation of the pulp or clarified water coming from various steps of the process.  
     
     
         10 . The process according to  claim 1 , comprising introducing said carbon dioxide into said broke pulp partly immediately after forming said broke pulp and partly upon completion of the broke treatment.  
     
     
         11 . The process according to  claim 1 , further comprising, during said step of bringing the broke pulp to a concentration and a pH close to that of the fresh pulp, at least one of (1) deflaking the broke pulp or (2) complementary cleaning of said broke pulp.  
     
     
         12 . The process according to  claim 11 , further comprising introducing the carbon dioxide at least at a first point so as to obtain a suitable intermediate pH during at least one of said deflaking step and said cleaning step, and at a second point located after said broke treatment, so as to have a pH of the diluted broke pulp substantially compatible with the pH maintained in the step of mixing said broke pulp with said fresh pulp.  
     
     
         13 . The process according to  claim 1 , wherein the pH of the diluted broke pulp is between 5.5 and 8.5.  
     
     
         14 . The process according to  claim 12 , wherein the intermediate pH of the pulp during at least one of the deflaking step and the cleaning step is between 7.5 and 9.  
     
     
         15 . The process according to  claim 14 , wherein the intermediate pH is between 8 and 8.5.  
     
     
         16 . The process according to  claim 11 , comprising injecting the carbon dioxide: 
 into white water fed during said step of forming said broke pulp,    into white water employed during said diluting step, after formation of said broke pulp,    into white water after said broke treatment, before mixing with the fresh pulp,    into the broke pulp after its formation, and before said deflaking or cleaning steps, or    into the broke pulp, at the end of broke treatment, and before mixing with the fresh pulp.    
     
     
         17 . The process according to  claim 11 , comprising introducing the carbon dioxide (1) in a white water between the steps of forming said broke pulp and deflaking said broke pulp, so as to obtain a pH of between 7.5 and 9 during said step of deflaking said pulp and (2) in a white water between said step of deflaking said broke pulp and the end of the broke treatment, so as to have a pH of the diluted pulp coming from the broke treatment substantially equal to the pH maintained for mixing the broke pulp with the fresh pulp.  
     
     
         18 . The process according to  claim 17 , comprising introducing the carbon dioxide into the white water between the steps of forming said broke pulp and deflaking said broke pulp so as to obtain a pH of between 8 and 8.5.  
     
     
         19 . The process according to  claim 1 , wherein the carbon dioxide is essentially in gas form.  
     
     
         20 . The process according to  claim 1 , wherein the carbon dioxide is essentially in liquid form.  
     
     
         21 . The process according to  claim 1 , wherein the carbon dioxide is partially in gas form and partially in liquid form.