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.

Description

CROSS REFERENCE TO RELATED APPLICATIONS[0001]This is a continuation of PCT application No. PCT / EP2006 / 004922, entitled “METHOD FOR LOADING FIBERS CONTAINED IN A PULP SUSPENSION”, filed May 24, 2006, which is incorporated herein by reference.BACKGROUND OF THE INVENTION[0002]1. Field of the Invention[0003]The present invention relates to a method for loading fibers contained in a pulp suspension, and more particularly to a method of loading cellulose fibers for producing paper or board.[0004]2. Description of the Related Art[0005]In the manufacture of paper, fillers, in particular precipitated calcium carbonate (PCC) or crushed or ground calcium carbonate (GCC), are standard substances which are used to reduce the fiber content and to improve the optical properties of the paper.[0006]Commercially available PCC or GCC fillers are products produced in bulk in special manufacturing facilities which can be associated with a paper mill in the form of a satellite plant. The online productio...

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Benefits of technology

[0017]A further advantage of the present invention is that under certain circumstances it is possible to economize by omitting a machine for thickening, such as the disintegrated pulp during the puling operation is diluted only to such an extent that the subsequent loading can be carried out. In other cases, in particular should greater demands in terms of cleaning of the stock be necessary (waste paper) or should separation of the fibers not be adequately achieved otherwise, it is also possible that thickening, such as in the form of a screw press, may be necessary. The filtrate from such thickening is returned directly into the pulping apparatus in a short circuit, to serve for dilution therein. This has the decisive advantage that the calcium hydroxide or calcium oxide is used optimally, as not only the water, but also the chemicals can be recirculated.

[0018]In many cases, the pulping operation is carried out not only with water, but also with the addition of pulping chemicals, in particular sodium hydroxide solution, in order to provide a basic medium. Here too, the present invention has advantages since the sodium hydroxide solution can be replaced by calcium hydroxide, which is required anyway for the precipitation reaction resulting in calcium carbonate which is carried out later.

Problems solved by technology

The online production of PCC has, however, never been, nor is it now, considered in the paper industry because of the special process necessary to produce PCC.

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