JPH06313285A - Method for pulping waste paper - Google Patents

Abstract

PURPOSE:To enable to recover pulp fibers for paper production by treating waste paper, even when milk packs or plastic film-laminated paper sheets are contained in the waste paper or even when security documents packed in corrugated board boxes are treated in the state of the corrugated board boxes as such. CONSTITUTION:This method for pulping waste paper comprises feeding waste paper raw materials together with water, sodium hydroxide, a deinking agent, etc., into a pulper, grinding the waste paper raw material with the pulper into sizes enabling the flow transfer of the ground products into the next process, discharging the ground products, dehydrating the discharged ground paper pieces, charging the dehydrated paper pieces into an aging tower 33, accumulating and storing the charged paper pieces in the tower for approximately 10-20hr for their swell, thus pulping most of the swollen paper pieces, discharging the pulp and the swollen ground paper pieces from the bottom of the aging tower, and subsequently transferring the discharged pulp and the swollen ground paper pieces into dust-removing and refining processes 37, 38, 39 for disaggregating and refining the products.

Description

Detailed Description of the Invention

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention is applied to papermaking by processing not only conventional raw materials but also milk packs that are difficult to recycle, waste paper laminated with plastic films, and confidential documents stored in corrugated boxes together with corrugated boxes. The present invention relates to a pulping method of used paper for recovering fibers.

[0002]

2. Description of the Related Art In order to recycle general waste paper such as newsprint, magazines and office paper into fibers for papermaking, the waste paper is put together with caustic soda and deinking agent in a pulper equipped with a strainer having a large number of circular holes with a diameter of 2-3 mm. The crushing action of the disintegrating blade, which is in contact with the top surface of the strainer and rotates at high speed, rubs the paper against the strainer, and the turbulent shearing action of the turbulent flow generated in the pulper by the rotation of the disintegrating blade roughly disintegrates the paper, The rough disaggregated fiber is drawn downward from the hole of the strainer by a pump runner that rotates integrally with the disaggregation blade below the strainer, and is discharged to the outside.

[0003]

Even when the above-mentioned general waste paper is roughly disintegrated with a pulper, a large amount of foreign matters such as magazine binding metal fittings, newspapers and strings used to bundle the magazines remain in the pulper. Must stop the operation and perform cleaning to remove impurities accumulated by the workers inside the pulper. Then, when a milk carton or waste paper laminated with a plastic film is treated with a pulper, the paper adheres to the aluminum foil in the case of a milk carton, and the paper adheres to the plastic film in the case of a laminated paper with a plastic film. Therefore, it is difficult to roughly disaggregate the paper. Further, when the confidential documents in the corrugated cardboard box are supplied to the pulper together with the corrugated cardboard box, it takes a very long time until they become disaggregated fibers.

[0004]

In view of the above, according to the present invention, even if the waste paper raw material contains a milk carton or a laminated paper with a plastic film, or the confidential document contained in the corrugated cardboard box is supplied together with the corrugated cardboard box. Easy to make papermaking fibers,
It relates to a pulping method that can be recovered by supplying waste paper raw material to a pulper together with water, caustic soda, deinking agent, etc., and crushing the waste paper raw material into a size that can be sent to the next process with a pulper and discharging. Then, the discharged pieces of crushed paper are dehydrated and put into the aging tower, and the inside of the tower is filled with 10 to 20 pieces.
Most of the pulp is pulped by accumulating and accumulating the pieces of paper for a period of time, and then the swollen crushed pieces of paper are pulled out from the bottom of the aging tower and sent to the next dust removal and selection process for disaggregation and selection. It is characterized by

[0005]

EXAMPLES Pulper strainer holes typically have a diameter of 2
Although it is ~ 3 mm, in the present invention, for example, the diameter is 70-80 m.
Pulper 3 with strainer having circular holes and elliptical holes of about m
No. 1 is sufficient, and the disintegration that is performed by the conventional pulper is scarcely performed, and the waste paper supplied with water, caustic soda, deinking agent, etc. rotates at high speed on the strainer, and the disturbance caused by the rotation of the disintegration blade. Due to the shearing action of the flow, the strainer is crushed to a size that allows it to pass through circular holes and elliptical holes having a diameter of about 70 to 80 mm. In this way, since the pulper 31 mainly crushes waste paper, even a milk carton or a laminated paper with a plastic film can be easily made into small pieces.
Further, in the case of a cardboard box containing a confidential document, both the cardboard box and the confidential document inside can be easily pulled into small pieces. And
The strainer hole has a diameter of 70 to 80 mm, so the binding metal for binding paper, the string that was bundled, the empty cans such as juice that has been mixed in, and other miscellaneous contaminants also pass through the hole of the strainer and crushed paper pieces. It is discharged from the pulper together with. This means that it is almost unnecessary to suspend the operation of the pulper and carry out the cleaning operation to remove the impurities accumulated inside.

The crushed paper pieces discharged from the pulper 31 are supplied to the screw press 32 by the pump P ₁ , dehydrated and concentrated there to reduce the volume, and then introduced into the aging tower 33 from above. By accumulating and storing in an aging tower for 10 to 20 hours, during that time, crushed paper pieces swell and pulp most of them, and it is easy to release the ink components that adhere to the laminated aluminum foil and plastic film. Make it easy to peel off. After a lapse of 10 to 20 hours, pulp and swollen crushed paper pieces are sucked from the bottom of the aging tower by the pump P ₂ and supplied to the screw press 34, and the liquid containing the deinking agent is dehydrated and concentrated, and then put into the diluting tank 35. The cyclone 36 is supplied to the cyclone 36 from the diluting tank 35 by the pump P ₃ , and the contained metal such as staples, binder metal fittings, empty cans, etc. are removed and supplied to the first separator 37. still,
The crushed paper pieces sucked from the bottom of the aging tower by the pump P ₂ may be directly supplied to the cyclone 36. Most of the swollen crushed paper pieces are already pulped, but when they pass through the pump P ₂ sucking from the aging tower and when they pass through the screw press 34 for dewatering the deinking agent, they are supplied to the cyclone. Therefore, when passing through the pump P ₃ , a disaggregation action is exerted, and in addition to this, disaggregation action is also exerted by the disaggregation vanes which rotate in proximity to the wedge wire 11 of the first separator, which will be described later, so that a large amount of disaggregation fibers are produced in the first separator. Can be recovered.

The first separator 37 is equipped with a perforated plate having a large number of holes having a diameter of about 2 to 3 mm and a screen having slits having a width of about 0.1 to 0.2 mm. For example, the fiber passing through is
0 part is collected, and 35 parts of the raw material containing impurities and the like that do not pass through the perforated plate and 5 parts of the raw material that does not pass through the screen are discharged. 35 parts of the raw material that does not pass through the perforated plate, then the diameter of 4-5
It is supplied to the second separator 38 having a perforated plate having a large number of holes of about mm, 29 parts of the raw material that cannot pass through the holes are discharged, and the remaining 6 parts and the raw material 5 that does not pass through the screen of the first separator 5 Parts are supplied to the third separator 39. The third separator is provided with a screen having slits of the same size as the first separator, and collects 10 parts of the fiber that has passed through the slit from 11 parts of the supplied raw material, and discharges 1 part of the raw material that cannot pass. Then, 70 parts in total of 60 parts of the fibers collected by the first separator 37 and 10 parts of the fibers collected by the third separator 39 are supplied to the next processing step, for example, the deinking flotation separation step.

2, 3 and 4 show a first separator,
This is proposed by the present applicant in Japanese Patent Application No. 3-297707, and its outline is as follows. Reference numeral 3 designates a fixed horizontal cylindrical cylinder with both ends closed, and 1 and 2 are three chambers in the axial direction inside the horizontal cylindrical cylinder 3, namely, a first chamber I at one end, a third chamber III at the other end, and an intermediate chamber. These are the first and second barrier walls that partition into the second chamber II. In the first chamber I, there are provided in a tangential direction a supply pipe 5 for a stock solution containing a swollen rough disintegrated paper piece and a dust pipe 6 for discharging most of the impurities contained in the stock solution. It is connected. Further, a dust removing pipe 7 is connected to the second chamber II, and a paper material take-out pipe 8 is connected to the third chamber III. These tubes 5, 6,
7 and 8 are tangentially connected to each room. The first wall 1 has six concentric fan-shaped openings 1 ′ in the circumferential direction, and the edge of each fan-shaped opening 1 ′ facing the first chamber I has a diameter of about 2.5 mm. The fan-shaped plate 9 having a large number of circular small holes is detachably attached, and the fan-shaped opening 9 is closed by the fan-shaped plate 9. The opening ratio of the circular small hole 10 to the first wall is about 3
It is 0%. Similarly, the second wall 2 has six fan-shaped openings 2'of equal size in the circumferential direction, which are concentric with each other, and each fan-shaped opening 2'has an edge facing the second chamber II. The wedge wires 11 are attached in a radial direction in parallel with each other while keeping a narrow gap, and an innumerable slit 12 having a groove width of about 0.13 to 0.2 mm is provided by the narrow gap of the wedge wire. The flat bottom side of the wedge wire 11 having a triangular cross section faces (see FIG. 4). The opening ratio of the slit 12 to the second wall is 30 to 40%.

Then, a rotating horizontal shaft 13 is passed through the center of the third chamber III and from the outside of the cylindrical barrel 3 to the central portions of the second wall 2, the second chamber II and the first wall 1 of the cylindrical barrel. Provided on the rotating horizontal axis 13 is a dust vane 14 that rotates in the first chamber I in the vicinity of the first wall 1 and removes a contaminated portion that tends to be blocked in the circular hole 10 of the first wall 1. A disaggregation blade 15 that rotates in the vicinity of the second wall 2 inside the second chamber II is attached. As shown in the upper half of FIG. 3, a part of the dust-dispersing blade 14 is two sickle-shaped blades 14 retracted in an arc shape with respect to the rotation direction (arrow).
a, 14a. Further, the disaggregation blade 15 is almost the same as the disintegration rotor blade of the pulper, and has three disaggregation blade pieces 15a that are substantially radially protruding and are evenly spaced in the circumferential direction. A built-up layer 16 having a thickness of about 2 mm and made of a hard metal alloy such as stellite is provided in a U-shaped cross-sectional shape that encloses the edge portion facing toward. Reference numeral 17 is a bearing stand for the rotary horizontal shaft 13, and 18 is a pulley fixed to the rotary horizontal shaft 13 for transmitting rotational power to the rotary horizontal shaft 13. The diameters of the flange walls 1 and 2 are about 1 m2.
In the case of 0 cm, the horizontal axis of rotation 13 rotates at 300 to 400 RPM.

When the rotating horizontal shaft 13 is driven to rotate and the stock solution containing the swollen rough disintegrated paper pieces is supplied to the first chamber I at one end of the horizontal cylindrical barrel 3 by the supply pipe 5, the circular shape of the first dividing wall 1 is obtained. Contaminants that try to be clogged in the small holes 10 are splashed off by the rotating dust-removing blades 14 and separated from the wall 1, and the foreign matter that cannot flow through the circular small holes 10 flows into the dust pipe 6 together with other contaminants. First with some
It is discharged from the chamber I and supplied to the second separator.

Of the fine impurities that have sunk through the circular small hole 10 of the first wall, the impurities that are trying to be clogged in the slit 12 of the second groove wall 2 having a minute groove width (0.13 mm) are close to the wall. Is separated from the second wall by the disintegrating blade 15 that rotates and is discharged from the second chamber together with a part of the stock liquid that flows into the dust removal pipe 7 together with other remaining fine contaminants, and is supplied to the third separator. . Then, the rough disaggregation paper piece that has flowed into the second chamber from the first chamber is the disaggregation blade 1
5 is subdivided into fine fibers by turbulent flow generated by the rotation of the disaggregation blade, and is slid by the disaggregation blade 15 that rotates while contacting the slit 12 when passing through the slit 12. Then, it is taken out from the take-out pipe 8 connected to the third chamber and sent to the subsequent process such as the flotation device. The wedge wire 11 forming the slit 12
As described above, since the flat bottom piece faces the inside of the second chamber II as described above, the groove width of the slit is not expanded by water pressure or foreign matters.

From the viewpoint of pressure loss, the groove width of the slit 12 of the second wall 2 for partitioning the second chamber II and the third chamber III is very small (0.13 to 0.2 mm). The stock in the first chamber, which becomes resistant to the flow of the stock solution flowing from the chamber to the third chamber through the second chamber and tries to flow into the second chamber through the circular small hole 10 of the first wall 1 The liquid stays in the room,
Similarly, the stock solution in the second chamber, which is about to flow into the third chamber through the slit 12 of the second wall 2, stays in the chamber. Therefore, the diameter of the circular small hole 10 of the first wall 1 is smaller than that of the slit or the round hole of the conventional first-stage separator,
Contaminants in the stock solution that stagnant in the first chamber are agitated by the rotation of the dust vanes 14, and large contaminants approaching to try to block the circular small holes 10 are blown from the first wall 1 by the dust vanes. The contaminants that have been separated and thus cannot pass through the circular small hole 10 are smoothly discharged from the first chamber I to the outside together with a part of the stock solution flowing into the dust pipe 6, and the pressure loss is not increased. The contaminants discharged from the first chamber I by the dust pipe 6 and supplied to the second separator are about 80% of the contaminants in the stock liquid flowing into the first chamber, and It is comparable to the total amount of contaminants discharged by three conventional separators in which the slits or round holes are gradually reduced. The second chamber I is passed through the circular small hole 10 of the first wall 1
Contaminants in the stock solution that entered the I chamber and stagnant in the room were also stirred by the rotation of the disaggregation blades 15, and the contaminants approaching to try to clog the slits 12 were separated from the second wall 2, thus Contaminants that cannot pass through the slit 12 are smoothly discharged to the outside together with a part of the stock liquid flowing into the dust removing pipe 7,
Does not increase pressure loss. When the outflow pressure of the stock solution from the third chamber III is 0.65 kg / cm ^2, the inflow pressure of the stock solution into the first chamber I is 0.7 kg / cm ^2, the outflow from the third chamber When the pressure is 0.9 kg / cm ² , the inflow pressure into the first chamber is 1.0 kg / cm ² , and the pressure loss is 0.0
Only rises from 5 to 0.1 kg / cm ² . A flow control valve (not shown) whose opening can be adjusted is connected to the dust pipe 6 and the take-out pipe 8, respectively, and these control valves are used to feed the paper to the first chamber at the beginning of operation. If the inflow pressure of the stock solution and the outflow pressure of the stock solution from the third chamber are adjusted to values showing a predetermined pressure loss, the pressure loss hardly changes thereafter, so that it is not necessary to adjust.

In the second chamber II, the disaggregation blade 15
Rotation causes turbulent flow, and the swollen paper pieces in the stock solution are not only subdivided by touching the disintegrating blades, but are also torn by the shearing action of the turbulent flow to be disintegrated into fibers and pass through the slits 12. Or, those that cannot pass through the slit are slid by the disintegrating blades that rotate and move in contact with the slit, pass through the slit, pass through the slit, enter the third chamber III together with the stock solution, and are taken out from the take-out pipe 8. The material that has passed through the slits of the third separator is sent together with the floating separation step and the like.

At the center of the first wall 1 through which the rotating horizontal shaft 13 penetrates, there is provided a bearing cylinder 19 in which the end of the shaft 13 to which the dust-dispersing blade 14 is attached is fitted to the inner circumference. The rotating horizontal shaft 13 is steady. Further, an inner peripheral cylinder 20 is provided at the center of the second peripheral wall 2 through which the rotary horizontal shaft 13 penetrates.
A seal is provided between the penetrating part and the penetrating part to seal. The bearing 21 for fixing the rotating horizontal shaft 13 on the bearing stand 17 is provided with an elongated hole 22 in the front-rear direction parallel to the horizontal shaft 13, and the bearing 21 is mounted on the bearing stand 17 by a bolt 23 passed through the elongated hole. The bearing base 17 is provided with adjusting bolts 24, 24 'which come into contact with the bearing 21 from the front and rear, and the bolt 23 is loosened.
Are moved in the front-rear direction so that the intervals between the first cutting wall 1 and the dust-discharging blade 14 and between the second cutting wall 2 and the disaggregating blade 15 can be adjusted.

As described above, the first separator divides the inside of the horizontal cylindrical cylinder into three chambers in the axial direction by the first and second walls, and swells the stock solution containing the coarse disintegrated paper pieces. Flow through the second chamber to the third chamber, a large number of small holes are provided in the first wall, and a large number of slits having a fine groove width are provided in the second wall. By making resistance to the flow of the liquid, the stock liquid is stagnated in the first chamber and the second chamber, and most of the impurities contained in the stock liquid are contained in the first chamber and the foreign substances are contained in the second chamber. The rest of is smoothly separated and removed without causing an increase in pressure loss. Therefore, it is possible to remove dust with one separator, which has conventionally been connected in series with three to four separators having holes with successively smaller diameters. Since the fluctuation of the pressure loss hardly occurs, the fluctuation of the pressure loss is constantly monitored, and when it becomes higher than the limit, the opening of the flow control valve on the extraction pipe side is reduced to reduce the pressure loss. When it goes down, the number of steps to restore the opening of the control valve to the original value can be saved. Further, the coarse disaggregation paper piece is disintegrated into a fibrous shape passing through the slit by the cooperative action of the disaggregation blade rotating in the second chamber in the vicinity of the second wall and the slit having the minute groove width of the second wall. As a result, a large amount of disaggregated fibers can be recovered.

The raw material containing impurities discharged from the dust pipe 6 in the first chamber of the first separator is a normal separator provided with a perforated plate having a large number of holes with a diameter of 4.3 mm.
The plastic film piece and the aluminum foil piece that cannot be passed through the hole are discharged to the second separator 37 of the table, and the raw material that has passed through the hole and the dust removal pipe 7 in the second chamber of the first separator are discharged. The discharged raw material is branched and supplied to three third separators 38 which are normal separators having a screen having a slit having a width of about 0.13 mm. Second
The pores of the porous plate of the separator can be made larger because the raw material that has only been crushed by a pulper is large, and thus the contaminants contained in the porous plate are also large. Most of the pieces (film pieces, aluminum foil pieces, water resistant paper pieces, etc.) are also large, so even if the holes are large, they can be easily separated and removed.
The load on the third separator can be reduced. The screen of the third separator is the slit 12 of the first separator.
It may be formed of a wedge wire in the same manner as the wedge wire 11 forming the. This third separator discharges a small amount of impurities that cannot pass through the slit, and collects a small amount of disaggregated fibers that have passed through the slit without waste. In the third separator, a disaggregation blade similar to the disaggregation blade 15 of the first separator that rotates in proximity to the wedge wire 11 may be rotated in proximity to the screen to perform the disaggregation action. The contaminants discharged from the second separator are dehydrated by the screw press 43, reduced in volume and discharged.

The disaggregated fibers thus collected by the first separator and the third separator are supplied to the flotation / separation tank 40, and the bubbles ejected from the tank bottom are adhered to the ink components contained in the fibers to float the ink components. The separated fibers from which the ink components have been removed are discharged to the cushion tank 41. Then, it is supplied from the cushion tank to the two filter devices and the cleaning device 42 by the pump P ₄ for cleaning and concentration, whereby the white clay and the ink components remaining in the fibers are washed away and collected in the stock chest 44, and the stock chest. From the pump P ₅ to the screw press 45 for dehydration and concentration, the discharged fiber is added with a bleaching agent and, in the case of colored paper, a dyeing device 46 to a kneader 47, and the kneader 47 is disintegrated. Then, sterilize, put into the bleaching tower 48 from above, accumulate and store for 8 to 12 hours, and bleach in between.
Perform sterilization. And 8 from the bottom of the sterilization and bleaching tower 48
After ~ 12 hours, the fibers are drawn out by the pump P ₆ , supplied to the paper machine through well-known steps such as concentration adjustment, dust removal, etc. to make a medium-quality paper, sterilize, and 8-12 from the bottom of the bleaching tower 48.
After a lapse of time, the fiber is pulled out by the pump P ₇ , supplied to the extractor 49, the screw press 50, and the filter device 51, washed and concentrated again, and then the fiber is recovered to be a raw material for tissue paper making.

[0018]

As is apparent from the above, according to the present invention, the waste paper supplied to the pulper is crushed to a size that can be sent to the next step without being disintegrated by the pulper, and the crushed paper pieces are It was accumulated and stored in the next aging tower for 10 to 20 hours, swelled, and the swelled crushed paper pieces were pulled out from the aging tower and disintegrated in the next dust removal and selection process, so it was laminated with a milk pack or plastic film. Even used paper such as paper, which is conventionally difficult to recycle, can process confidential documents in a cardboard box together with the cardboard box and collect them as papermaking fibers.

[Brief description of drawings]

FIG. 1 is a flow sheet of the present invention.

FIG. 2 is a vertical side view of a first separator.

FIG. 3 is a sectional view taken along line III-III in FIG.

FIG. 4 is an enlarged sectional view taken along line IV-IV in FIG.

[Explanation of symbols]

 31 Pulper 33 Aging Tower 37 1st Separator 38 2nd Separator 39 3rd Separator

Claims (1)

[Claims] 1. A pulper containing waste paper, water, caustic soda,
It is supplied together with a deinking agent and the like, and the waste paper raw material is crushed and discharged by a pulper to a size that can be sent to the next step, and the discharged crushed paper pieces are dehydrated and put into a aging tower, and then placed in a tower. For about 20 hours, most of the pulp pieces are pulped by accumulating and accumulating them to swell the paper pieces, and then the pulp and the swollen crushed paper pieces are pulled out from the bottom of the aging tower and sent to the next dust removal and screening step. A method for pulping used paper, characterized by disaggregation and careful selection.