FI105699B - Method and application for treatment of stock from pulp or paper mill - Google Patents

Description

105699

METHOD AND USE FOR THE PROCESSING OF PULP MILLS IN A PULP OR PAPER MILL

The present invention is directed to a method and apparatus for treating a pulp or pulp mill pulp, in particular a slurry, according to the preamble of the independent claims below.

5

TECHNICAL BACKGROUND

At various points in the papermaking process, the wreck contains fiber, and possibly fillers, adhesives, coatings, etc. Thus, the wreck contains both usable raw materials and wastes that must be removed from the reusable raw material. The purpose of the wreck treatment system is to return valuable raw material components in the wreck back to the process. 15 I «(•«

Wrecking of the wreck • «i

I

• <I

', The first step of processing is the pulping of the wreck. There are many pulp reefers for paper machine and coating machine a 20 below. In the event of a breakdown, the production of the machine can be run.

«· · V 'In addition, powders are found in the vicinity of polishing calenders and length cutters.

• · · "« ·. _____ «·. _____ · * · ...

The edge strips of the cutters can be applied to one of the above or a separate edge stripper. • · · ”* usually has its own pulper for dismantling the reels.

* · • · • · ·. ...___ ': A: Because the factory wreck contains plastics and other impurities, the system usually also has a two-stage sorting system before you _____ 30 before precipitation and defibration.

Pulppering refers to mixing a web-shaped wreck with water to form a pumpable pulp slurry in which the fibers are at least partially separated.

105699 2

The wreck is leveled in the pulper. Fibers in dry pulp or paper are firmly attached to each other. It is necessary to soak the pulp in water to dissolve the fiber-to-fiber bonds. Thereby the fibers also swell as water penetrates into the pores of the fiber. External forces are also required to separate the fibers. They are produced by vigorous mixing of the pulp slurry. This is achieved by a rotor disposed in the pulper. It works like a pump impeller; the mass ejects from the periphery outwards and at the same time a strong suction is created at the center of the rotor.

The degradability of scrap paper depends on the quality of the paper. Degradability is reduced by paper bonding, surface treatment and coating. The most easily degradable paper grades are newsprint and other uncoated woody paper grades.

15 Calendering impedes the degradation of these grades. Extremely difficult to decompose grades include wet strength and coated paper grades as well as kraftliner and kraft paper.

Wreck storage: The coated paper grade production line has: Y: 20 separate wreckage towers for uncoated and coated wrecks. This is because you want to dispense a controlled coating of debris back into the paper machine, for example because of the ash adjustment of the base paper.

Sorting and defibrating the wreck 25 The sorting of the wreckage mass is all the more necessary the higher the quality of the finished product.

• · • · · • · ·. ···. Poorly disintegrated wreckage or debris that comes with the wreck ^ (eg plastic, sticks, sand) causes problems in the process and • breaks on the paper machine.

30 The modern wreck sorting and defibration line includes 105699 3 typically - a screening screen, which is usually a pressure screen with a hole punch, - wreckers 5 - a pressure screen, a pressure screen with a slot or hole punch, and - a reject screen, which is either a vibration screen or a pressure screen

The purpose of the screening filter is to remove solid particles, such as pieces of tape, head-rope pieces, sticks, from the wreck.

The pressure sorter returns undissolved fiber bundles back to defibration.

The purpose of the wreck rejector is to separate the debris and other solid particles to be removed from the pulp and to return the authorized pulp to the sorting cycle and back to the process.

In the case of papers with fillers, etc.

; :: inorganic components, the mineral-containing fraction 20 is further taken to a separate recovery plant (recovery of filler components).

i. .

• ·

As stated above, the handling of glued, surface-treated and coated paper grades is very difficult. The organic components in the adhesives and coating pastes cause agglomeration of the fiber and mineral pigments. The resulting agglomerates do not decompose • · · - - - - \ * · in known dispersants, thus rendering much of the treated material unusable. in the sense that it cannot be pushed back into the process.

'·' 30 Therefore, such materials often have to be disposed of, for example by landfill. This is not only an environmental disadvantage but also, above all, a significant loss of fiber raw material and valuable inorganic filler.

105699 4 The coated paper machine can produce about 10 tons of material per day. Recycling and reusing this material in the process would result in significant cost savings on an annual basis.

It is an object of the present invention to overcome the above problems and to provide a process for treating a pulp stock containing fiber and other components in a pulp or paper mill to disintegrate the agglomerates therein.

The method can also handle difficult wreckage species and thus recover the useful raw materials contained therein and reintroduce them into the process. This treatment can also significantly improve the optical properties of the paper produced, i.e., increase both the brightness and the opacity.

The method can also be used to treat pulp stock containing extractives in an adhesive form (in agglomerate form) and to decompose the agglomerates therein to render the extractants in a non-adhesive form.

. . These objects are achieved by the process according to the invention; ; 20 device and device that is characterized by what it is

«I I

v is shown in the character portion of the following claims.

• ·: .v The term “pulp stock” covers any slurry made from wood: pulp. The pulp may be mechanical, semi-chemical or chemical. fresh pulp, or it may be any wreckage * * * present in papermaking, or a mixture of said components.

The term "wreck treatment" as used in this invention also includes deinking of printed paper to remove printing ink: · 30 pulp.

«* · * • *

Devices operating on the principle of repulsive milling are known from, for example, Danish patent publications DK 104778, Finnish patent applications FI 945945, FI 946048 and FI 955474. housing and arranged to rotate therein in opposite directions.

The device used in the method of the invention comprises: - a first rotor with blades, - a second rotor with blades concentric with the first rotor, arranged to rotate in an opposite direction to the first rotor such that the periphery of the first rotor and the periphery of the second rotor are spaced; a feed opening for the rotor hub.

The material stream to be treated (pulp stock) is led to an inlet opening to the center of the rotors and is made to flow through the nested rotor blades to the periphery of the outboard rotor and exit therefrom as a discharge flow 20 out of the device.

• · ......

For example, this method can be used to treat well different types of slurry fractions, including very high fiber content and high filler content. wrecks. Thus, the slurry fraction may be a coated slurry from the powders, a filler-containing flow to the filler recovery plant, a rejection from the filler recovery plant, or a reject from the wrecking and deburring plant.

• · · • · • ·, · · · _____. ···. The method is also well suited for reducing the infectious matter of various types of fresh • • - -: ---- ”wars.

: V 30 • · · --------------

The solids content of pulp stock can vary greatly,.:. suitably in the range of 3 to 60%.

According to a suitable embodiment, "the suspension obtained as a backflow mill discharge stream 105699 6 is recirculated in whole or in part to the backflow mill one or more times. According to another suitable embodiment, apparatus is used in which two backflow mills are connected in series.

In one embodiment, the device according to the invention is provided with its own housing.

The device has at least two rings. The energy consumption of the device increases with the increasing number of rings, and therefore the optimum number of rings may be 2-5.

The invention is explained in more detail in the accompanying figures, in which

Fig. 1A is a vertical sectional view of a backing mill used in the method of the invention,

Figure IB shows an alternative solution to Figure IA,

Figure 2 is a horizontal sectional view of the device of Figure 1,

Fig. 3 illustrates an apparatus for treating a wreck by the method of kek-20,

Figure 4 shows another apparatus in which a device according to the invention has been used to handle a wreck, * >>>; Figure 5 illustrates a third apparatus in which the m · of the invention. . The apparatus according to the invention has been used for the treatment of the wreck, Fig. 6 shows the fourth apparatus in which the apparatus according to the invention has been used for the treatment of the wreck. shows a fifth apparatus in which a device according to the invention. · * ·, 30 has been used for treating a wreck • · · * * S 66Π / • '1' Figure 8 schematically illustrates a wreck processing process for a paper mill to produce coated paper,:, Figures 9a-9d, 10a-10d and 11a-lld show microscopic images of 105699 7 samples taken from the rejection of a filler recovery plant, and

Figure 12 illustrates the effect of the skewed method of the invention on the reject particle size distribution of a filler recovery plant.

5

Fig. 1A is a vertical sectional view of a counter mill 20 used in the method of the invention, comprising a housing 10 fitted with a rotor 11 provided with blades 1a, Ib, 3a, 3b ... etc (individual blades 10 are shown in greater detail in Fig. 2). Also housed within the housing is a second rotor 12 which is concentric with the first rotor 11. The second rotor 12 is also provided with blades 2a, 2b ..., 4a, 4b ... etc. The blades 1a, Ib ..., 15a, 2b ..., 3a, 3b of the first rotor 11 and the second rotor 12. oh arranged in concentric rings 1, 2, 3 ... such that the rings 1, 3, 5 of the first rotor 11 and the rings 2, 4 of the second rotor 12 are spaced apart. Then the rotors 11 and 12 with their blades can rotate freely in different directions.

At the end of the housing is provided an opening 14 which opens into the center of the rotors 11 and 12, which acts as a feed opening for the pulp block. The housing wall is provided with an opening 15 which opens into the outermost wing and serves as an outlet.

• * • m • ·

Rotors rotating in opposite directions provide • · -: rr —____—----. .

. 25 powerful centrifugal forces that effectively keep the flow-throughs moving, which the stator-rotor system ♦ ·: "The T-theme would not be able to.

• «_________

In Fig. 2, which shows a device of the type IA of Fig. IA, · · · - V '30 in horizontal section (indeed modified so that each of the rotor Hall, 12 has one circumference more than I i · - ------ .. .. in the device of Fig. 1), the directions of rotation of the rotors are shown. Of course, each rotor can also rotate in the opposite direction.

• * i _ 'i 35 The circumferential wall of the countermeasure mill housing need not be in the immediate vicinity of the 105699 8 rotor pair, but may be farther away, whereby the housing may be very loose. The function of the enclosure is then essentially to serve as a container for the treated material. Fig. 1B shows a solution in which the apparatus used in the method according to the invention is not provided with its own fixed installation housing. The device comprising a pair of rotors 11, 12 is fitted to a container 30 having an opening 14a in communication with the inlet 14 and having an outlet 15a for the treated material stream 10.

According to the solution of Figure 2, the horizontal distance L between the frames 1, 2, 3 ... is about 3 mm and the same between all the rings. If desired, the device may be constructed or adjusted 15 so that the distance L between adjacent rings decreases or increases toward the outer periphery 7 of the device (not shown).

According to one embodiment, the device may be constructed such that the distance S between the outer peripheral blades is smaller or greater than the distance between the inner peripheral blades.

I I f! The measures just mentioned may have the potential to 'ensure that coarser' 'material can be fed to the device (e.g., sludge slurries with large agglomerate * * 25 gates), but still provide enough «·: V for a finely divided final product. The essential advantage is that · ·· V: the number of blades on the rotor blades and the spacing (tightness) between the blades are selected as needed. For example, the distance between the rings as well as the distance between the »30 blades in the ring may be reduced towards the outside. In this case, the disintegrating agglomerates are forced into an increasingly tight space before the resulting suspension is removed from the apparatus.

• I

«T • ·»

According to Figure 2, the wings of the perimeter wings having a rectangular cross-sectional profile are turned so that the collision surfaces of the 105699 9 wings are radial. The wings of one or more of the circles may also be rotated to increase the collision power, for example, so that the direction of their collision surfaces differs from that of the beam. Of course, the cross-sectional profile of the blades 5 can also be changed from rectangular to triangular, whereby the impact surfaces of the blades are not parallel but form a certain angle with each other.

Fig. 3 illustrates the apparatus 10 used in the invention, wherein the return mill 20 is connected to a collecting tank 16, which in the tests was 300 1. The collecting tank 16 has a mixer driven by an engine M. Reference numeral 17 is a feed pipe and 18 a discharge pipe. The exhaust pump is marked with reference number 19.

Figure 4 shows another apparatus having only a non-return mill 20 and an inlet outlet pipes 17 and 18.

Figure 5 shows a third embodiment of the apparatus in which the material flow 20 accumulated in the collection tank 16 is partially returned to the return mill 20 by means of a twist pipe 21. This arrangement returns f 4 .....

suitably 1/4 ... 1/2 of the material entering the tank 16 back to the counter mill 20. The rest goes from the overflow pipe. . 18 forward to the process.

Fig. 6 shows a hardware solution which is otherwise similar to the solution of Fig. 5 except that two • ·: .V counter-mills 20 and 20 'are connected in series. Instead of passing the material flowing in the overflow pipe 1818 back into the process, it is led to another counter mill 20 ′, · · · .......

30 from which material is removed through conduit 18 '.

I - ------------ • - • ΤΓ. - ~ “laitte: - :: t« «* ... · Figure 7 shows a hardware solution which is otherwise the same as Figure 6 except that there is no material recycling back to the first reciprocating mill 20.

105699 10

EXAM

A factory test was carried out in which 5 samples were taken from the treatment line of the coated paper mill's refuse pulp line, which was fed to a back-mill for processing. The test was conducted under operating conditions such that small side streams were fed to the counter mills at the test points.

exam points:

Figure 8, which is a very schematic representation of the paper-10 mill wreck treatment process, is marked with test points 1-4.

# 1 stream from the wreck handling and sorting section to the filler recovery plant before the dispersant (before the Supraton-15 dispersant counter, before the re-agitator) # 2 after the wreckage hopper (wreck tower) • # 3 after wreck sorting and defibration. ./ second reject # 4 «# 4 filler recovery plant reject • 1 1 20 At each test point, a sample was taken before and after the rebound mill. Test point # 1 also sampled • · V.5 after the Supraton dispersant. This sample serves as a reference for the mill mill because the Supraton disperser and mill mill were connected in parallel.

i • i

t I

• I

*; 25 The test driving variables were:

• I I

• · • · ·: \ j 1) Feed quantity to the counter mill 2) Rotational speed of the counter mill 105699 11 3) Effect of recycling in the counter mill on the disintegration result 4) Serial connection of several counter mills

In the laboratory, samples were analyzed for: 5 Microscopic images were taken of all samples. Ashes and consistency were determined from the streams (feed samples) entering the Counter Strike Mill.

In addition, SR values (drainage resistance, Schopper-Riegler) and particle size distribution 10 (Sedigraf) of some samples were determined. In addition, laboratory sheets were used to make test sheets using samples from different test points as subcomponents.

Score

Solids content (consistency): 15 test point 1 40% test point 2 4.3% test point 3 7.2% test point 4 17% i • «a • * .. ______ I | I .. ...

Figures 9a-9d show microscope images (90x magnification) • · ·· —- · -. . from a sample taken at test point 4, untreated • · · (9a), treated once in a counter-mill (9b), treated • · ............

'·' * Twice in the counter mill (9c) and treated three times in the counter mill (9d). From the figures it is noted that • · *, V 25 in the untreated sample (9a) contained large filler reagents.

: glomerates and that each round through the counter mill, · * ·, caused a substantial reduction in particle size.

i · I

• · - • · · - - -------------

Figures 10a-10d show the result of another similar but a · · test carried out in another factory, with sample f i 30 corresponding to the above test point 4. The magnification is 90x. Figure 10a shows an untreated sample, 10b, once handled in a back mill, 10c, sample twice treated in a back mill, and 10d sample treated three times in a back mill. Again, these patterns show the effective ability of the counter mill to degrade pigment agglomerates.

An experiment was also performed which monitored the effect of the back mill on the sample of test point 4. The counter mill was coupled prior to the pre-vortex purification tank of the filler recovery plant. Figures 11a-11b show 10 microscope photographs (90x) of samples taken at test point # 4 before (11a) before the counter mill was coupled, 1.5h later (11b), 3h later (11c), and 4.5h later (11d).

Figure 12 illustrates the effect of the method of the invention on the reject particle size distribution of a filler plant. The X-axis of the figure represents the particle size and the Y-axis the undertrain, i.e., the proportion of material whose particle size is smaller than the particle size indicated by the X-axis. The light bars represent material that has not been treated in the counter-20 ridge. The dark bars represent the material that has been treated once in the counter mill. Material with a particle size smaller than 15 μπι is less than 15 μπι, which is virtually a valid acceptance for the process. Untreated • I «| . material acceptability was only about 27%, while single • ·,. The 25-fold treated material increased its acceptability to approximately 91% *.

· «• ·« • · ·

In the experiments described above, a counter-mill, • · V, was used, which had three studs in the upper rotor and 2 studs in the lower * s *. The upper rotor motor 30 rotated at 1500 rpm and the lower rotor motor rotated at 2000 rpm. The maximum flow rate to the back flow mill was 6 m3 / h.

• · «•« • · «« ·

By optimizing the driving conditions, of course, even better results than those described above can be obtained.

105699 13

According to a particularly recommended driving mode, the outer peripheral rotation speed of the devices is 40 to 80 m / s.

A factory test was also carried out in which the pulp after the wreck tower was treated exclusively in a counter mill in accordance with the invention, after which the pulp was run on a paper machine. The paper specifications were at least as good as under normal conditions of use. Retention improved and filler consumption decreased because the pigment from the coating replaced the new filler.

From the experiments performed it can be seen that the invention provides considerable advantages. The device of the invention connected to the wreck treatment apparatus would allow for a substantial reduction in the vortex cleaning apparatus, which is currently 6 steps. Only a 2-step vortex cleaning would suffice for a wreck or a vortex purifier feed treated with a device according to the invention.

Laboratory sheets were also made to simulate the quality of the paper produced by the papermaking machine: Y: 20 in the event that the pulp after the wreck tower is treated exclusively in a back mill, then the pulp I <----- is run on the papermaking machine.

f <i ·,, 15% t · · ____ J of the wreck tower was used for laboratory sheets; post-pulp. The rest was normally • · · __ ____ * · * 25 materials going to the paper machine (fresh pulp, pigments, etc.). For comparison, three sets were made with the post-wreck tower • ♦ V. · pulp a) untreated b) once driven through a bounce mill ("1 Passage" and c) twice driven through a bounce mill ("2 getting through "). Each series measured «· f .....

.M. 30 consistency, ash, charge and turbidity of wreckage. The results are shown in Table 1. Sheets were prepared from each set, a a a -. 7 which contained 15% of the mass of rejects and were measured on the TV ___ _:, '> i brightness and opacity. The results are shown in Table 2.

105699 14

table 1

Characteristics of rejection stock untreated 1 Throughput 2 Throughput consistency,% 11.74 8.44 18.54 5 ash,% 84.1 84.3 84.8 charge -57.3 -46.3 -53.6 turbidity 114 18 26

Table 2

Optical Characteristics of Laboratory Sheets as a Function of Wreckage Component-10 Untreated 1 Passage 2 Passage

Lightness,% (ISO) - top of sheet 84.42 85.85 86.30 - bottom of sheet 83.84 85.65 86.16 15 Opacity,% 71.72 76.31 75.53

From the results shown in Table 2, it is found that the optical milling properties of the paper are surprisingly favored by the impact mill treatment of the wreck mass component. A brightness increase of 1-1.5 percentage points is usually considered to be 20 very significant achievements. Traditionally, the increase in brightness is achieved by adding bleached cellulose, which in turn reduces opacity, or by adding expensive titanium oxide or the like pigment.

Based on the results presented above, it has been demonstrated that the lightness and opacity of 25 papers can be simultaneously increased by treating one or more multipliers in a rejection mill and thereby leading to a pulp stream so treated.

• · · * · • · · · · · ·

The results presented in Table 1 also show that. . The turbidity of the aqueous phase of 30 pulp slurries decreases quite significantly as a result of the • · · * · '·' counter mill treatment. The high turbidity of the aqueous phase of the untreated • · ♦ *. * * Pulp slurry is due to substances in colloidal form which subsequently adhere specifically to the dewatering equipment of the papermaking machine. these

IM

35 substances typically include extracts such as pitch and latex. The colloidal form, i.e. the adhesive, is a small particle agglomerate on which the latex particles are deposited. Experiments performed show that the anti-shock mill treatment removes these adhesive agglomerates, either by attaching them to fibers or pigment particles, or by dispersing them into small, non-adhesive particles. Also, the maintenance of the pulp charge remains largely unchanged in favor of such a mechanism of action.

From the above-mentioned results, it is obvious that treating any pulp stock containing extractant by the process of the present invention can reduce the amount of adhesive extractant. The pulp stock may be a coated debris, such as in the experiment described above, any other reject stream or fresh pulp (mechanical, semi-chemical or chemical) that is processed during pulping (e.g. before pulp drying) or during papermaking. the pulp is led to the paper machine. The counter-mill can be equipped with the same. talc or other dispersant which "traps" the dispersed particles and prevents the formation of harmful agglomerates also leads to the pulp 20. In particular, mechanical v / w pulps such as hot pulp contain high concentrations of extractant. It would be extremely difficult to introduce talc or dispersant into the pressurized process equipment, but ... by treating the pulp in a separate working step according to the invention could solve the problem.

·

Ml -------- • Il • · · • _____ 1-. . The above embodiments of the invention are merely exemplary, · · · ·· .- -. .

30 of the invention. It will be apparent to one skilled in the art that the various embodiments of the invention may vary according to the claims set forth below. inks.

• «f ...... - · • ·« · · ______ • t * ♦ · • · · ....

2 ----------.

Claims (15)

105699 16 Patent Claims ET A process for treating a pulp stock containing pulp or paper mill fiber and / or possibly other components, such as mineral components, in order to decompose the agglomerates therein, characterized in that the pulp stock is fed to a reciprocating mill device (reciprocating mill (20)) comprising: a first rotor (11a), (1a, Ib ... 3a, 3b ...), - a second rotor (12) concentric with the first rotor and having blades 10 (2a, 2b ... 4a, 4b ...), arranged to rotate in the opposite direction to the first rotor such that the periphery (1, 3, 5 ...) of the first rotor (11) and the periphery (2, 4 ...) of the second rotor are disposed interleaved, and an inlet (14), whereby the pulp stock is introduced into an inlet (14) which opens into the center of the rotors (11, 12), from where it is flown through the blades of nested rotors (11, 12). the outer rotor and exit therefrom as an outflow of 20 earth from the device. Process according to Claim 1, characterized in that the pulp stock is a slurry containing fillers and / or coating pigments. • · The process according to claim 1 or 2, characterized in that the solids content of the pulp stock varies between 3% and 60%. • 1 · 1 A method according to claim 2 or 3, characterized in that the slurry is a coated wreck resulting from pulping. • i • 1 5. A method according to claim 2 or 3, characterized in that the slurry is a filler-containing flow to the filler recovery plant. 105699 17 Method according to claim 2 or 3, characterized in that the slurry is a reject of a filler recovery plant. Method according to Claim 2 or 3, characterized in that the slurry is a reject leaving the wrecking and deburring plant. A method for increasing the optical properties of paper, i.e., brightness and opacity, characterized in that the coated wreck resulting from pulverization is treated in a counter mill according to any one of claims 1 to 3, after which it is fed as one component to a paper machine. 9. A method for reducing the content of an adhesive extractant in a mechanical, semi-chemical or chemical pulp, the pulp stock is processed in a counter mill according to the method of claim 1, after which the treated stock stock is fed to a paper machine or dried. The process according to claim 9, characterized in that talc or other dispersing agent is also fed to the back mill. Method according to one of Claims 1 to 10, characterized in that the suspension obtained as a result of the removal of the high-speed mill is recirculated in whole or in part to the counter-mill one or more times. • · ♦ ... • · • ·. ···. Use of a device (20) for treating a pulp stock containing pulp or paper mill fiber and other components, such as mineral components, to disintegrate the agglomerates therein. ".:. 30 characterized in that the device comprises: - a first rotor (11) with blades (1a, Ib ... 3a, 3b ...), 105699 18 - concentric with the first rotor, with blades (2a, 2b ... 4a, 4b) ...) with a second rotor (12) arranged to rotate in an opposite direction to the first rotor such that the periphery (1, 3, 5 ...) of the first rotor 5 (11) and the periphery (2, 4) of the second rotor. .) are disposed intermittently, and - a feed opening (14) which opens into the center of the rotors (11, 12). Use according to claim 12, characterized in that one or both rotors (11, 12) comprise at least two rings, and that the rings (1, 3, 5 ...) of the first rotor (11). and the peripheries (2, 4 ...) of the second rotor are disposed interleaved. Use according to Claim 12 or 13, characterized in that the rotors (11, 12) are arranged in the housing (10) and that the inlet (14) opens at the end of the housing and the outlet wall (15) is provided on the wall of the housing. opens to the periphery of the outer rotor. Use according to claim 12, 13 or 14, characterized in that between the wings of the outer periphery! the distance (S) is less than the distance between the wings' of the inner periphery. i I * f I «• a *« · «« »» · a * • a »i aaa • · • *» »il • f • Il • • • aa •« · Aaa 105699 19