Method for loading fibers contained in a pulp suspension

Abstract

The present invention serves for loading a pulp suspension (S) with calcium carbonate. Liquid calcium hydroxide as milk of lime ( 7 ) is added during or before the pulp operation ( 1 ) carried out to form the pulp. By introducing gaseous carbon dioxide ( 8 ) into the pulp suspension thus treated, a chemical reaction is triggered therein, in which the finely divided calcium carbonate is precipitated. The present invention is particularly economic and effective due to the early addition of calcium oxide or calcium hydroxide.

1 . A method for loading a pulp suspension containing cellulose fibers with calcium carbonate, comprising the steps of:
 introducing one of a calcium oxide and a calcium hydroxide in one of a liquid form and a dry form into a pulp;   forming the pulp suspension from said pulp;   introducing a gaseous carbon dioxide into the pulp suspension;   precipitating calcium carbonate by way of the carbon dioxide;   performing a pulping operation; and   adding at least one of the calcium oxide and the calcium hydroxide one of during said pulping operation and before said pulping operation.   
     
     
         2 . The method of  claim 1 , wherein said pulping operation is carried out continuously. 
     
     
         3 . The method of  claim 1 , wherein said pulping operation is carried out discontinuously, at least a portion of the calcium hydroxide is metered into the pulp in a liquid form at a beginning of said pulping operation. 
     
     
         4 . The method of  claim 1 , wherein said pulping operation is carried out in a pulper. 
     
     
         5 . The method of  claim 1 , wherein said pulping operation is carried out in a pulping drum. 
     
     
         6 . The method of  claim 5 , wherein at least one of the calcium oxide and the calcium hydroxide is added to a charging region of said pulping drum. 
     
     
         7 . The method of  claim 1 , wherein said pulping operation is carried out in a consistency range of between 3% and 30%. 
     
     
         8 . The method of  claim 7 , wherein said consistency range is between 10% and 20%. 
     
     
         9 . The method of  claim 1 , further comprising the step of steeping the pulp with water and calcium hydroxide before said pulping operation. 
     
     
         10 . The method of  claim 9 , wherein said steeping step is carried out using a steeping drum. 
     
     
         11 . The method of  claim 9 , wherein said steeping step includes the step of spraying the calcium hydroxide onto the pulp. 
     
     
         12 . The method of  claim 1 , further comprising the step of adding the calcium hydroxide in the form of milk of lime, said milk of lime having a consistency in the range of 0.01% to 60% of existing solids content of a dry paper mass. 
     
     
         13 . The method of  claim 1 , further comprising the step of setting a time of between 0.01 and 10 minutes for the reacting of the calcium hydroxide. 
     
     
         14 . The method of  claim 1 , wherein the pulp has a consistency of between 40% and 100% of a starting material. 
     
     
         15 . The method of  claim 1 , further comprising the step of cleaning the pulp suspension of anionic trash, said cleaning step being carried out after said pulping operation. 
     
     
         16 . The method of  claim 15 , further comprising the step of executing a flotation process whereby ink particles are removed to thereby clean the pulp suspension. 
     
     
         17 . The method of  claim 1 , further comprising the step of thickening the pulp suspension prior to said introducing a gaseous carbon dioxide step. 
     
     
         18 . The method of  claim 17 , wherein a filtrate produced during said thickening step is used in said pulping operation. 
     
     
         19 . The method of  claim 1 , further comprising the step of converting the pulp suspension into a fine fiber crumb in a crushing step one of during and after said precipitation step, the fine fiber crumb being disperged. 
     
     
         20 . The method of  claim 1 , wherein said precipitation step is carried out at a consistency of between 5% and 60%. 
     
     
         21 . The method of  claim 20 , wherein said consistency is between 10% and 35%. 
     
     
         22 . The method of  claim 20 , further comprising the step of expending energy executing said precipitation step, said energy being between 0.3 and 8 kWh/t. 
     
     
         23 . The method of  claim 22 , wherein said energy is between 0.5 and 4 kWh/t. 
     
     
         24 . The method of  claim 1 , wherein said precipitation step is carried out at a temperature of between −15° and 120° C. 
     
     
         25 . The method of  claim 24 , wherein said temperature is between 20° and 90° C. 
     
     
         26 . The method of  claim 1 , wherein said precipitation step is carried out at a pressure of between 0 and 15 bar. 
     
     
         27 . The method of  claim 26 , wherein said pressure is between 0 and 6 bar. 
     
     
         28 . The method of  claim 1 , wherein said precipitation step is carried out with a pH value of between 6 and 10. 
     
     
         29 . The method of  claim 28 , wherein said pH value is between 6.5 and 8.5. 
     
     
         30 . The method of  claim 1 , wherein said precipitation step is carried out within a reaction time of between 0.001 minute and 1 minute. 
     
     
         31 . The method of  claim 30 , wherein said precipitation step is carried out within a reaction time of between 0.5 second and 10 seconds. 
     
     
         32 . The method of  claim 1 , further comprising the step of producing one of a paper and a board from the pulp suspension containing loaded cellulose fibers, said producing step generating white water containing calcium hydroxide which is used as a returned water in one of said pulping operation and for diluting the pulp. 
     
     
         33 . The method of  claim 1 , wherein the cellulose fibers used in said pulping operation consist at least in part of de-inked waste paper.