WO2006032333A1

WO2006032333A1 - Method and device for charging a fibre material suspension

Info

Publication number: WO2006032333A1
Application number: PCT/EP2005/008851
Authority: WO
Inventors: Klaus Doelle
Original assignee: Voith Patent Gmbh
Priority date: 2004-09-17
Filing date: 2005-08-16
Publication date: 2006-03-30
Also published as: US20070151681A1; DE102004045089A1; CN101014740A; EP1792008A1; BRPI0514926A; CA2580697A1

Abstract

The invention relates to a method for charging a fibre material suspension, which contains cellulose fibres, with calcium carbonate, said method consisting of the following steps: calcium hydroxide in a liquid or dry form or calcium oxide is introduced into the fibre material suspension, carbon dioxide is introduced into the fibre material suspension, calcium carbonate is precipitated from the calcium hydroxide by the carbon dioxide in a pressurised pressure container (2).

Description

Method and device for loading a pulp suspension

The invention relates to a method for loading a pulp suspension with calcium carbonate.

Several processes for loading pulp fibers with calcium carbonate are already known. No. 6,413,365 B1 describes a process in which fiber material is transported via a feed line together with calcium oxide and / or calcium hydroxide present in the suspension. From this, the pulp suspension is forwarded to a rotating distribution device. Carbon dioxide is introduced annularly into the pulp suspension as the reaction gas; As a result, calcium carbonate crystals are formed in the pulp suspension. About the rotating distributor, the calcium carbonate crystals are distributed in the pulp suspension. This process is referred to as a fiber loading process.

From DE 101 07 448 A1 a method for loading a Faserstoffsus¬ pension with calcium carbonate is known, in which the pulp suspension is fed to a crystallizer and is acted upon in this by shear forces auf¬ break larger fiber agglomerates in smaller or even in individual fibers, and in the crystallizer is used simultaneously as a reactor for the chemical precipitation reaction.

It is the object of the invention to further simplify a method of the type mentioned.

According to the invention, this object is achieved by a method with the following process steps:

Introduction of calcium hydroxide in liquid or dry form or of calcium oxide into the pulp suspension, introduction of carbon dioxide into the pulp suspension, precipitation of calcium carbonate from the calcium hydroxide by the carbon dioxide in a pressurized pressure vessel.

The invention describes a process for producing fibers laden precipitated calcium carbonate (FLPCC), the fiber raw material to be loaded being recycled paper, DIP (= deinked paper) paper, secondary pulp , bleached or unbleached pulp, mechanical pulp, bleached or unbleached sulphate pulp, pulp, cotton, and / or hemp fibers (predominantly cigarette paper) and / or any stock that is used on a paper machine.

With the method provided in accordance with this invention, the currently used filler material is replaced, supplemented or activated by the filler material made with the Fiber Loading (= Fiber Loading) process technology. Activation means that existing filler particles are superimposed by the fiber loading process or serve as nucleation nuclei, resulting in better optical properties.

In particular, the method is also suitable when using Flexolnk (water-based ink) printed paper, especially newsprint, for the recovery of the fiber raw material is used. The pressure particles consisting of Flexolnk can not or only with difficulty be separated by a flotation process. By means of the invention, it is now possible to incorporate fillers and foreign substances such as printing ink, impurities, stickies, and the like which are forcibly present in DIP papers into the fiber loading (= fiber loading) crystallization process, wherein already existing filler particles be superimposed by the fiber loading process or as crystallization nuclei serve.

The process is independent of whether the fiber raw material contains filler which has been produced by a precipitation process in batch reactors or by a milling process, or whether talc, titanium dioxide (TiO ₂ ), silicon, etc. are used. The milling process is also referred to as GCC process (GCC = ground calcium carbonate = ground calcium carbonate).

When a pulp suspension is treated with fiber-loading technology, a completely new product for the papermaking application area results in new and improved properties over a prior art product. The fiber-loading technology allows filler, in particular calcium carbonate, to precipitate directly in the stock preparation of a paper mill, which filler material is evenly distributed and deposited on, in and between the paper fibers.

The field of application of the fiber-loading process technology-produced filler extends to the fields of application of papermaking all types of paper including cigarette paper types, types of filter paper, types of sack kraft paper and paperboard and packaging paper, including those using recycled paper grades and DIP papers , Such packaging papers may have a filler content between 1 and 60% and / or have a white topcoat with a filler content between 1 and 60%. The loaded and produced types of paper may be made of recycled paper, deinked paper (DIP), secondary pulp, bleached or unbleached pulp, wood pulp, bleached or bleached sulphate pulp, pulp, cotton, and / or hemp fibers (mainly for cigarette paper) and / or any paper raw material are produced on a paper machine, regardless of whether the end product contains filler.

Pulp produced using fiber-loading combination process technology generally has a higher dewatering capability than pulp produced by other methods; The drainage capacity is 5 to 100 ml of CSF or 0.2 to 15 ⁰ SR depending on the required freeness. In addition, the fabric or pulp produced by the fiber-loading method has a lower water retention capacity of 2 to 25% depending on the raw material used for production. This enables a more effective production of different types of paper such as FL (FL = fiber loaded) - copying and printing paper of all kinds, FL-paper of all kinds, FL-newsprint of all kinds and FL-cigarette paper of all kinds, FL-B & P- Paper of all kinds, FL sack paper of all kinds and FL filter paper, because the existing water of the stock suspension can be removed faster. The fabric dries faster as well.

When a pulp suspension in papermaking is treated with the fiber loading technology, a completely new product results, which has new and improved properties over the papers available on the market. The fiber loading process described below makes it possible to precipitate filler directly in the stock preparation of a paper mill, in particular calcium carbonate, which is uniformly distributed and deposited exclusively on and in the paper fibers.

By a combination or by a single application of the measures described below according to the invention, it is achieved that exclusively precipitated calcium carbonate is prepared for the fiber loading process and already existing filler material is activated.

By using the fiber loading technology in the pulper or in the batch container, the optical properties of the paper suspension and of the raw material can be improved by 0.5 to 30 brightness points, preferably by 1 to 25 brightness points, mainly by the masking of impurities such as color particles or dirt. In addition, there is a conversion of non-activated pulp constituents which are present in the recycled paper stock. or incorporated in the DIP pulp, for example, unconverted calcium hydroxide, PCC (precipitated calcium carbonate = precipitated calcium carbonate), GCC (ground calcium carbonate = ground calcium carbonate), lime components, etc.

Advantageous embodiments of the invention will become apparent from the Unteran¬ entitlements, the description and the drawings.

According to one embodiment, as the starting material, aqueous fiber raw material, in particular aqueous paper stock, having a consistency of between 1 and 20% of pulp fraction is introduced into the pressure vessel, wherein at one

Share between 1 and 6% LC pulp material (low consistency), at one

Proportion between 6 and 10% of MC pulp material (medium consistency) and used in a proportion between 10 and 20% HC pulp material (high consistency).

Advantageously, the aqueous fiber raw material is diluted with dilution water to a pulp suspension having a consistency of between 0.1 and 20%, in particular with a consistency of between 2 and 18%, diluted.

In a suitable embodiment of the method, the pressure vessel is closed after introduction of the aqueous fibrous material and / or the dilution water through a sluice.

It is advantageous if the calcium hydroxide or the calcium oxide is mixed into the aqueous pulp in a range between 0.1 and 60% of the solids content of the mass of the dry pulp present.

The pH is preferably between 6 and 11, in particular between 6.5 and 10.5.

The reaction time is between 0.0005 and 30 minutes, especially in the range between 0.05 to 10 minutes.

Advantageously, the calcium carbonate can be precipitated by mixing in the carbon dioxide in a pressure range between 0 and 15 bar, in particular between 0 and 6 bar.

In one embodiment of the method it is provided that the Faserstoff¬ suspension and / or carbon dioxide by process water or Verdünnungs¬ water or water vapor during its dissolution in the pulp suspension or by the fiber loading process or by supplying heat energy from the outside, in particular by steam energy or electrical energy , is heated.

The carbon dioxide may be supplied before, during or after the addition of the carbon dioxide or the calcium hydroxide or the calcium oxide.

In this case, advantageously, the pressure vessel can be closed by a valve or a lock before the reaction of the fiber load and opened after the reaction.

The energy required for the precipitation of the loaded fibers is between 0.3 and 8 kWh / t, in particular between 0.5 and 4 kWh / t, if no device for grinding the pulp is used. A grinding machine can also be connected upstream of the container if the fiber pulp is already sufficiently dissolved. The grinding machine can also be connected downstream of the pressure vessel in an alternative embodiment of the invention.

Preferably, the process temperature is between -15 and 120 ⁰ C, in particular between 20 and 90 ⁰ C. The fiber loading process produces rhombohedral, scalenohedral, and spherical crystals.

Crystals with dimensions between 0.05 and 5 μm, in particular between 0.3 and 2.5 μm, can preferably be produced by this method.

It is possible to use static and / or mobile, in particular rotating, mixing elements for mixing the pulp suspension.

Advantageously, it is also provided that the process is carried out in a pressure range between 0 and 15 bar, in particular between 0 and 6 bar.

According to the invention, in a preferred embodiment, it is also possible to simultaneously undergo a grinding treatment within the pressure vessel during the precipitation process.

The invention also relates to a device for carrying out the method.

According to the invention, the device is characterized in that it comprises a feed device for feeding fiber raw material and a pressure vessel.

In an advantageous embodiment of the method, it is provided that the pressure vessel comprises a lock or a valve, via which the fiber or raw material for producing the pulp suspension with loaded fibers is supplied. Advantageously, the pressure vessel has inlets for diluting or pressing water, for calcium oxide or calcium hydroxide and for carbon dioxide.

In addition, the pressure vessel comprises a rotor for mixing the fibrous suspension. The invention will be described in detail in an embodiment with reference to the ein¬ zigen figure. This shows a schematic view of a Vor¬ direction for loading a pulp suspension.

A fiber raw material is fed to a pressure vessel 2 via an inlet pipe 1 (FIG. To set and limit the inflow, a lock 3 is present between the inlet pipe 1 and the pressure vessel 2, which is opened and closed by a motor-operated shutter mechanism.

Dilution water, calcium hydroxide in liquid or solid form or calcium oxide or chemicals are supplied via further supply connections 4, 5, 6, so that, when the fiber raw material was first fed, until it reaches a filling level 7, above this level 7 forms a filling of the pressure vessel 2 with the serving for the pulp loading calcium hydroxide together with the water and / or the diluting water in which it is dissolved forms.

To mix the fiber raw material with the calcium hydroxide so that it penetrates into the fibers, a rotor 8 is used, which has either at the bottom of the Druckbe¬ container 2 and / or further above a propeller or the like. The rotor 8 is driven by a motor 9.

Preferably, at least one inlet 10 for carbon dioxide is present in the lower region of the pressure vessel 2, through which the calcium hydroxide reacts to Calciumcar¬ carbonate. After the pulp is dissolved and loaded with calcium carbonate, it is discharged via a discharge pipe 12 provided with a valve 11 to a machine for producing a fibrous web.

At the pressure vessel 2 is preferably also a measuring point 13 for measuring the chemical composition of the contents of the pressure vessel 2, in particular for measuring the pH, arranged. LIST OF REFERENCE NUMBERS

1 inflow pipe

2 pressure vessels

3 lock

4 supply connection

5 supply connection

6 supply connection

7 level

8 rotor

9 engine

10 carbon dioxide inlets

11 drainage pipe

12 valve

13 measuring point

Claims

claims

A method of loading a pulp suspension of cellulosic fibers with calcium carbonate, comprising the steps of:

Introducing calcium hydroxide in liquid or dry form or of calcium oxide into the pulp suspension,

Introduction of carbon dioxide into the pulp suspension,

Precipitation of calcium carbonate from the calcium hydroxide by the

Carbon dioxide in a pressurized pressure vessel (2).

2. The method according to claim 1, characterized in that is introduced as starting material aqueous fiber raw material, in particular aqueous paper stock, with a consistency of between 1 and 20% Faserstoff¬ share in the pressure vessel, wherein at a proportion between 1 and 6% LC pulp material , with a share between 6 and

10% MC pulp material and in a proportion between 10 and 20% HC pulp material is used.

3. The method according to claim 2, characterized in that the aqueous fiber raw material is diluted with dilution water to a Faserstoff¬ suspension having a consistency between 0.1 and 20%, in particular with a consistency between 2 and 18%, is diluted.

4. The method according to any one of claims 1 to 3, characterized in that the pressure vessel (2) after the introduction of the aqueous Faserstoff¬ material and / or the dilution water through a lock (3) is concluded.

5. The method according to any one of claims 1 to 4, characterized in that the calcium hydroxide or calcium oxide is mixed into the aqueous pulp in a range between 0.1 and 60% of the existing solids content of the mass of the dry pulp.

6. The method according to claim 5, characterized in that it is carried out at a pH between 6 and 11, in particular between 6.5 and 10.5.

7. The method according to claim 5 or 6, characterized in that the reactivity of the calcium hydroxide is between 0.0005 and 30 minutes, in particular in the range between 0.05 to 10 minutes.

8. The method according to any one of claims 1 to 7, characterized in that calcium carbonate by mixing the carbon dioxide in a

Pressure range between 0 and 15 bar, in particular between 0 and 6 bar, is precipitated.

9. The method according to any one of claims 1 to 8, characterized in that the pulp suspension and / or the carbon dioxide by Prozeß¬ water or dilution water or water vapor during its development solution in the pulp suspension or by the fiber loading process or by supplying heat energy from the outside, in particular by steam energy or electrical energy is heated.

10. The method according to any one of claims 1 to 9, characterized in that the carbon dioxide is supplied before, during or after the addition of Kohlen¬ dioxide or calcium hydroxide or calcium oxide.

11. The method according to any one of claims 1 to 11, characterized in that the pressure vessel (2) is closed by a valve or a lock (3) before the reaction of the fiber load and opened after the reaction.

12. The method according to any one of claims 1 to 11, characterized in that the energy required for the precipitation of the loaded fibers between 0.3 and 8 kWh / t, in particular between 0.5 and 4 kWh / t, if no device for grinding of the pulp is used.

13. The method according to claim 12, characterized in that the pulp is subjected to a grinding treatment within the pressure vessel (3) during the precipitation process.

14. The method according to any one of claims 1 to 13, characterized in that the process temperature between -15 and 120 ⁰ C, in particular between 20 and 90 ⁰ C, is.

15. The method according to any one of claims 1 to 14, characterized in that rhombohedral, scalenohedral and spherical crystals are produced.

16. The method according to claim 15, characterized in that the crystals are produced with dimensions between 0.05 and 5 .mu.m, in particular between 0.3 and 2.5 microns.

17. The method according to any one of claims 1 to 16, characterized in that static and / or movable, in particular rotating, Mischele¬ elements (8) are used for mixing the pulp suspension.

18. A device for carrying out a method according to one of claims 1 to 17, characterized in that it comprises a feed device (1) for supplying fiber raw material and a pressure vessel (2).

19. The device according to claim 18, characterized in that the pressure vessel comprises a lock or a valve, via which or the fiber raw material for producing the pulp suspension with loaded fibers can be fed.

20. The apparatus of claim 18 or 19, characterized in that the pressure vessel (2) inlets (4, 5, 10) for dilution or

Press water, for calcium oxide or calcium hydroxide and for carbon dioxide.

21. Device according to one of claims 18 to 20, characterized in that the pressure vessel (2) comprises a rotor (8) for mixing the Faser¬ suspension material.