JPS5934834B2 - Method and apparatus for recovering paper fibers from raw materials including waste paper - Google Patents

Description

DETAILED DESCRIPTION OF THE INVENTION Waste paper has become an important source not only for past paper fiber utilization but also for reuse in new paper products, and waste paper raw materials of various types and grades are used in the paper industry and paperboard manufacturing. It has become a necessity for businesses.

In recent years, the trend to reuse post-consumer paper stock has only increased, and this trend is particularly evident in the patents granted to the applicant, for example, U.S. Pat. , 736, 223.

When recycling waste paper used on a commercial scale, collection,
Due to the economic constraints of sorting and packaging, used paper products often contain a large amount of inorganic contaminants in addition to plastics and rags, so cleaning and screening them usually involves various technical challenges. Met.

It is difficult to separate contaminants in the waste paper mixture from the paper using conventional bulky waste removal equipment or centrifugal cleaners.

A more important problem is that it is difficult to separate garbage such as plastics, which has a specific gravity similar to that of cellulose fibers, and such garbage may be mixed in at a weight ratio of 15% or more of waste paper.

In addition, the pulper that is normally used first to crush wastepaper is very effective in thrashing, but the disintegration is incomplete, and therefore the pulper passes through relatively small extraction holes, e.g., 3/8 inch or less in diameter. In order to crush paper to such a degree, it would require pulping for quite a long time.

For this reason, not only is it difficult for the plastic component in the mixture to become fine, but it also accumulates in the pulper and becomes a hindrance to extracting the disintegrated paper fibers.

Such a situation lowers the efficiency of the pulper, unnecessarily increases power consumption, and causes problems such as the pulper having to be frequently stopped to scrape out the inside.

Up until now, attempts have been made to increase the extraction pores of the pulper in order to avoid the above-mentioned problems, but this has only created new problems.

For example, the disintegration of the charged waste paper is incomplete, resulting in a large number of paper fiber fragments that are as large as plastic fragments, making it difficult to separate them by screening.

During this time, the problem can be solved by treating the mixture of fibers and various pieces with a deflaker that disintegrates only the paper without reducing the particle size of the plastic.

However, processing using this deflaker requires that all of the plastic, paper pieces, and defibrated paper fibers be processed by the defibrator, resulting in unnecessary power consumption.

A technique effective in solving the above problems is disclosed in commonly assigned US Pat. No. 3,877,410.

According to this patent, the pulper is used only for thrashing rather than for complete defibration of the paper, and the slurry that has been subjected to thrashing and centrifugal cleaning is screened with a large consistency to mix the disintegrated paper fibers with plastic etc. The stations in the system are arranged to separate at high speed and then deflaker the material that does not pass through the screen and recirculate the material that passes through the screen.

According to the above-mentioned U.S. Pat. No. 3,877,410, the pore diameter of the extraction plate of the pulper is quite large, more than 1 inch, so it is essential to pass all the extracted raw material through a fine screen to remove the disintegrated raw material. Ta.

All material that does not pass through the screen, which contains a large amount of good quality fibers, is disintegrated in a deflaker and then screened in a tailing screen, where the material that passes through the screen is returned to the feed line to the first screening station or one of the pulpers. be done.

It is clear that this system is a significant advance over conventional approaches for recovering fibers in particular from municipal solid waste.

The present invention further improves upon the teachings of the above-mentioned US Pat. No. 3,877,410 while retaining all its advantages.

In other words, the present invention completely disintegrates most of the waste paper material charged into the pulper at a relatively high speed, and the power consumption in this case is reduced to the continuous disintegration of lightweight waste such as plastics that interferes with pulping and extraction. By providing the pulper with a sufficiently large extraction hole suitable for the continuous separation of the above-mentioned lightweight waste, the present invention is capable of reducing the processing power required for the total amount of waste paper charged. The feature is that most of the paper fibers that have become defibrated are taken out, and all of the paper fibers that are subjected to the defibration action are defibrated.

As a result, it is initially thought that the refining will be carried out excessively, but the efficiency of the deflation force may be reduced to the point where there is no need to further disintegrate the raw material.

According to the invention, the pulper is provided with two extraction plate regions with virtually different pore sizes.

The pore size in one region is relatively small, 1/8 to 3/8 inch, typically 3/16 inch, and this region communicates with the extraction chamber from which the raw water is continuously fed to a storage tank of appropriate volume. is extracted.

The pore size in the other region is larger, 1/2 to 2 inches, typically 1 inch, and communicates with another extraction chamber.

The first fractionated slurry of the raw water extracted from the above-mentioned small-diameter extraction hole mainly consists of almost completely disintegrated paper fibers and a very small amount of floating debris such as plastics.

The second preparative slurry also contains a significant amount of fully disaggregated fibers and incompletely disaggregated fibers, but this is dominated by floating debris such as plastic sheets or films.

It is recommended that the hole diameter of the second extractor plate be selected so as to prevent clogging of the pulper or unnecessary load on the rotor by continuously removing the above-mentioned floating debris.

The above-mentioned second preparative slurry is first centrifugally cleaned to remove contaminants with a large specific gravity, and then filtered through a screen having a porous surface with a pore diameter somewhat smaller than the above-mentioned small-diameter extraction hole, i.e. 1/16 to 3/3 A screen with a 16 inch perforated plate, typically 1/8 inch, is desirable.

The feedstock passing through this screen consists primarily of mostly disintegrated paper stock.

Therefore, it is transferred to a storage tank to be mixed with the raw water extracted from the first extraction plate.

The feedstock that does not pass through the above-mentioned screens contains almost all floating debris from the pulper, but it also contains a significant amount of undisintegrated paper stock, which can be re-recovered.

This is further disintegrated by a deflaker, and the processed material from the deflaker is fed to a tailing screen having a hole diameter of 1/4 to 1/2 inch, which is relatively larger than the first screen.

The raw material that passes through this tailing screen is recycled to the pulper, and the material that does not pass through the tailing screen, which is mostly floating garbage such as plastic, is discarded.

Alternatively, the deflaker can be removed from the processing system and the screen similarly used to separate floating debris and return recoverable paper stock to the pulper.

An advantage of the invention is that the extraction plate region as a whole performs the function of extracting the small pore size of the raw material, so that no further disintegration is required.

At the same time, the large-pore extraction area continuously removes floating debris from the pulper that obstructs the small-pore extraction plate.

Furthermore, only a small part of the extraction plate has a large hole diameter, and the first
The screen flow can be correspondingly reduced to minimize the load when deflation forces are used as well as the recirculation of the disintegration feed water to the pulper.

This increases the efficiency of each processing station and increases the overall production of useful fibers.

Embodiments of the invention will be described in detail below with reference to the accompanying drawings, which illustrate embodiments of the invention.

The main parts of the machine in the equipment system shown in the figure include a processing tank 10, a rotor 11 rotating within this tank, and an extraction hole located below the rotor with a relatively small hole diameter, that is, 1/8-3/8 inch. a second extraction plate 13 with extraction holes of relatively large diameter, i.e. 1/2-2 inches;
There is a pulper that incorporates an extraction area consisting of.

As shown in the figure, the extraction plate 12 has a wider area than the extraction plate 13 and occupies about 90% of the total extraction area.

Each of the extraction plates 12 and 13 communicates with a separate extraction chamber below it, and each of these extraction chambers is provided with an extraction conduit 14, 15, respectively.
is provided.

The conveyor 20 carries the waste paper raw material to the tank 10.
In this case, the charging amount can be arbitrarily selected depending on the raw material content of commercially available "waste paper" or waste paper that becomes municipal waste.

The bulky waste removal device 22 is adjacent to the tank 10 and is interconnected via a conduit 23.

Water is continuously supplied from the pipe line 24 to the treatment tank via the coarse sludge removal device 22 and its connecting pipe 23.

Good examples of pulpers suitable for use in the stations described above are U.S. Pat.
No. 88, and a bulky waste removal device is disclosed in No. 3,549,092.

The basic characteristics of a pulper are to mix the waste paper raw material and water using mechanical shearing force, hydrodynamic force, and impact, and to efficiently mix the solid raw material in the tank through the porous surface of the extraction plate 12 at high speed. The point is that it can be crushed.

Typically, this pulper also includes U.S. Patent No. 3,549,
Climbing removal device 25 for removing sharp objects, large sheets of plastic, etc. as shown in No. 092
is installed.

The pulper 10 is operated continuously, while waste paper and water are added one after the other at such feed rates that the solids content is maintained at 2-8%, in practice around 3-5%.

A first preparative slurry consisting of paper and water that has been disintegrated to the extent that it can pass through the small diameter extraction holes of the extraction plate 12 is pumped to the pump 2.
6 is continuously withdrawn from the corresponding extraction chamber via line 14 into a surge tank 30 and further processed in conventional manner for cleaning and purification screening requiring raw water.

A second preparative slurry consisting of water and crushed raw materials that has passed through the large-diameter porous surface of the extraction plate 13 is transferred to the pipe line 1 by the pump 33.
If this slurry contains a considerable amount of impurities with a high specific gravity such as metal or glass, it is sent to a centrifugal cleaner 34 by a pump 33 to remove these impurities with a large specific gravity. It is desirable to not only remove it to prevent damage to the screen in subsequent steps, but also to simplify the screening process itself.

The slurry cleaned by the cleaner 34 contains a significant amount of relatively large undisintegrated paper pieces and similarly sized pieces of plastic, etc., but the initial pulping process When the pulper is used, the paper fibers that have been completely disintegrated pass through the extraction plate 13 together with most of the floating debris.

This slurry is therefore subjected to a screening process in screen 35 in a manner that allows at least a large portion of the substantially completely disintegrated paper to pass through, while leaving undisintegrated paper stock, plastics, and other objects to be rejected.

The actual configuration of the screen 35 is described, for example, in U.S. Pat.
It is preferable to use the one disclosed in No. 835,173.

The screen 35 comprises a housing 40 having at its upper end a tangential inlet port 41, an outlet port 42 for receiving raw water and sending it to the surge tank 30 from a line 43, and a discharge port 44 for the raw material not passing through the screen. It is shown.

There is a screen cylinder 45 inside the housing 40,
A rotor 46 rotates within this cylinder 40 and further carries vanes 47 spaced inward from the surface of the screen cylinder.

For purposes of the present invention, the pores in the screen cylinder are sized to allow passage of substantially only defibrated paper fibers and comparable particles.

Satisfactory results have been obtained using a screen constructed as described above, i.e. when the pore diameter of the porous surface is smaller than the pore diameter of the extraction plate 12.
/16-1/8 inch, preferably about 1/8 inch.

The material that does not pass through the screen 35 will therefore include a relatively small amount of undisintegrated paper chips and almost all floating debris such as plastics.

This flow of non-passage material is sent from conduit 49 to a deflaker 50, such as a discifier.
The stream exiting is fed to a tailing screen 55 suitable for separating fine paper fibers and undisintegrated paper from floating debris such as large plastics.

For example, screen 55 may be a Johnson-type vibrating flatbed screen having a porous surface with a larger pore diameter than screen 35, such as 1/4 to 1/2 inch.

Water necessary for operating the screen 55 is supplied to the pulper through a branch channel 56 of the water supply pipe 24.

Since the flow of the material passing through the screen 55 needs to be further pulped, it is returned to the pulper tank 10 at a point 57, and the material not passing through the screen is discharged from 58.

It should be noted that the use of this deflaker is optional.

In most cases this can be omitted and the non-permeate line 49 of the screen 35 connects directly to the tailing screen 35 to return the stream of screen permeate recycled from the screen 55 requiring further disintegration to the treatment tank. be able to.

The present invention has the great advantage of allowing equipment at each station of a processing system to be operated with an appropriate balance of load and efficiency.

For example, in a 300 ton/day system, the flow of almost disintegrated raw material water extracted from the small-pore extraction plate 12 is 3%.
265 tons on average at a consistency of
That's a ton.

Screen 35 therefore only needs to process about 35% of the total extraction volume.

The flow through the screen 35 is approximately 75 tons/day at a consistency of 2.7% and that to be processed by the deflation force 50 and/or tailing screen 55 is approximately 70 tons/day at a consistency of 3.4%. It becomes only

An average of 15%-20% of the feedstock from the tailing screen is removed and the remainder is recycled to the pulper.

Deflaker or tailing screen is screen 3
It should also be noted that if the capacity is such that it is not possible to process the entire amount of non-passage from 5, the flow can be split and the excess material recycled to the pulping tank 10, as shown by dashed lines 60 and 61. There is.

In the subsequent repulping process, most of this recycled raw material portion is sufficiently disintegrated to pass through the small-pore extraction plate 12 or screen 55, reducing the load on the deflaker and tailing screen. Ru.

That is, in either configuration, the equipment at each station can process material with only a fraction of the total load required for each operation, which not only minimizes operational maintenance costs and equipment wear, but also This makes it possible to improve processing efficiency.

[Brief explanation of the drawing]

The accompanying figure is a flowchart of a device system for an embodiment of the invention. 10... Processing tank, 11... Pulping device, IZ13... Extracting device, 27.33...
···screen.

Claims (1)

[Claims] 1. A method for recovering paper fibers for reuse from raw materials containing waste paper, characterized by comprising the following steps: (a) The consistency of the suspension is about 2-8. (b) continuously pulping the suspension in the tank to fragment the raw material; (c) relatively (d) continuously extracting a first preparative slurry consisting of a liquid passing through a small-diameter extraction hole and the debris from the tank; continuously extracting a second separate preparative slurry of said debris from said vessel; (e) screening said second preparative slurry through a small diameter pore having a pore size not larger than said small diameter extraction hole; (f) a step of mixing the raw water that has passed through the first screening step and the first preparative slurry; (g) a step of mixing the small-diameter extraction hole and the large-diameter extraction hole; a second screening step in which the raw material that did not pass through the first screening step is screened through pores having a pore size intermediate in size; and (h) the raw water that has passed through the second screening step is returned to the tank. The process of making it circulate. 2. The method according to claim 1, wherein the first screening step is performed through a pore having a smaller pore diameter than the small extraction pore. 3. The method of claim 1, wherein the small diameter extraction hole has a pore diameter of approximately 1/8 to 3/8 inch, and the large diameter extraction hole has a pore diameter of approximately 1/4 to 2 inch, and the small diameter extraction hole has a pore diameter of approximately 1/4 to 2 inches. Pore diameter is approximately 1/16 to 3/1
16 inches, and the intermediate pore size is approximately 1/4 to 1/2 inch. 4. The method according to claim 1, comprising the steps of applying a disintegrating action to the raw material that did not pass through the first screening step, and screening the disintegrated raw material through the pores having an intermediate pore size. 5. A device for processing raw materials including waste paper and recovering paper fibers suitable for reuse, characterized by consisting of the following components: (a) a pulping device including a processing tank; (b) a suspension (C) a device for supplying the raw material and water to the treatment tank at a flow rate such that the consistency of the liquid is maintained within the range of approximately 2-8%; (C) a device for continuously supplying the suspension in the treatment tank; (d) a pulping device for pulping and fragmenting the raw material;
an apparatus for continuously extracting a first preparative slurry consisting of a liquid and the debris from the treatment tank through a relatively small diameter extraction hole; and a device for simultaneously extracting a second preparative slurry consisting of the crushed pieces from the processing tank; (g) a device for mixing the raw water that has passed through the screen device and the first preparative slurry; (h)
a second screen device having pores with a pore size intermediate between the small-diameter extraction hole and the large-diameter extraction hole, and connected to receive the raw material that has not passed through the screen device;
and (i) a device for recirculating the raw water that has passed through the second screen device to the treatment tank. 6. The apparatus according to claim 5, wherein the small-diameter pores have a smaller pore diameter than the small-diameter extraction holes. 7. The apparatus of claim 5, wherein the small diameter extraction hole has a pore diameter of approximately 1/8 to 3/8 inch, the large diameter extraction hole has a pore diameter of 1/4 to 2 inch, and the small diameter screening hole has a pore diameter of approximately 1/8 to 3/8 inch. A device in which the pores have a pore diameter of 1/16 to 3/16 inch, and the intermediate pore diameter is 1/4 to 1/2 inch. 8. The apparatus according to claim 5, comprising a disintegrating device connected to receive raw material that has not passed through the screen device, and a device for transferring the disintegrated raw material to the second screen device.