JPH0429795B2 - - Google Patents

Description

DETAILED DESCRIPTION OF THE INVENTION The present invention relates to a method for removing lightweight foreign matter from a pulp manufacturing process.

In recent years, plastics and the like have been used everywhere, and it is difficult to avoid contamination with chips, which are raw materials for pulp.

The plastics mixed into the chips are reduced to fine particles by chemical and physical treatments during the pulp manufacturing process, which adversely affects the paper manufacturing process. Since the specific gravity of plastics is relatively close to that of pulp fibers, it is difficult to effectively remove them using conventional centrifugal cleaners, and flotation separation methods are also used.

Recently, as an improved flotation separation method, an impeller is attached to the separation tank to stir the foreign matter that has settled together with the pulp and to separate and float it (Japanese Patent Application Laid-Open No. 106793/1983).
However, in both of these methods, complete separation is impossible because the plastic is separated after being made into fine particles.

The finely divided plastics reach the paper manufacturing process and cause defects such as holes, streaks, and even paper breaks, so removing them requires a lot of effort and money.

The present invention provides a method and apparatus for separating plastics, etc. before they are made into fine particles, in order to eliminate problems in the paper manufacturing process caused by the contamination of lightweight foreign substances such as plastics, and to stabilize paper quality and production. purpose.

In order to easily and completely separate lightweight foreign substances, the present invention utilizes black liquor with a specific gravity of more than 1 while plastics, etc., are in a very light state of fineness, and separates them from knots with a large difference in specific gravity. Its structure is such that dilution water and knots are supplied to the separator 8, and the separated and floated lightweight foreign matter and the light foreign matter that floated up by the subsequent action of the knot recovery rake 21 are separated and floated. This is a method for separating lightweight foreign matter, in which the foreign matter is collected and removed by a foreign matter collection device 15, and the settled knots are collected by a knot collection rake 21.

The present invention will be explained based on examples and with reference to the drawings.

FIG. 1 is a schematic diagram showing an embodiment of the present invention,
The pulp that has been digested from a blow tank (not shown) is transferred to a seed box 4 by a seed pump 3.
and is separated into knots (undigested material) and pulp by a Janson screen 5. The separated knots are sent to a head tank 7 by a knot blower 6, mixed with a diluent sent from a filtrate tank 1 by a filtrate pump 2, and sent to a separation device 8. A separating device 8 separates light foreign matter adhering to the knots, and the knots are discharged into a chute 9, fed to a chip bin 11 by a chip conveyor 10, and re-digested. The diluent supplied together with the knot is discharged from the diluent outlet 18 and returned to the filtrate tank 1 for reuse.

Next, a separation method will be explained using the separation apparatus shown in FIG.

Dilution water and knots are supplied into the tank from the dilution water and knot supply port 12 of the separation device 8, and the turbulent flow generated by the baffle plate 14 mixes and stirs the supplies to separate and float light foreign matter.

Here, the diluent may be black liquor, white water from each process, or industrial water, but it is preferable to use black liquor from the viewpoint of recovering the chemical solution contained in the knots and increasing the difference in specific gravity. Furthermore, the diluent and/or the knots may be supplied from above the separation device 8.

On the other hand, lightweight foreign matter that adheres to the knot and settles out,
Thereafter, the knot collecting rake 21 is reciprocated by the eccentric cam 20 and the rake fulcrum 13 driven by the driving device 19, which may be used together with the lightweight foreign matter collecting device 15 or alone, and the knot collecting rake 21 is lowered by the raking action. At the same time, the knots in the knot are discharged upward along the oblique bottom 23, and at the same time, the lightweight foreign matter is separated from the knot and floated to the surface.

These lightweight foreign objects separated from the knot,
The liquid level in the tank flows toward the diluted liquid outlet 18, but a lightweight foreign matter recovery device 1 is placed above the liquid level in the separation device 8.
5 is installed, and the lightweight foreign matter recovery device 15 is provided with a plurality of net-like scrapers 22, and the net-like scrapers 22 have drive members arranged on both sides so that they go below the liquid surface when they come to the lower side during movement. Both ends are fixed to the net-like scraping board 2
2 moves in the opposite direction to the flow direction of the liquid to scoop up and collect the floating lightweight foreign matter, and when the mesh raking plate 22 reaches the upper part, the collected lightweight foreign matter is separated from the mesh raking plate 22 , and fall onto the tray 16.

A net-like partition plate 17 is provided in front of the diluted liquid outlet 18.
is installed over the entire width of the tank to prevent floating lightweight foreign matter from re-mixing into the diluted liquid and knots after separation.

On the other hand, the knots that have separated the lightweight foreign matter and settled at the bottom of the separation device 8 are deposited on the slanted bottom extending toward the chute 9 from the bottom near the front of the baffle plate 14 below the tip of the lightweight foreign matter recovery device 15. The knots are carried out to the chute 9 by a knot collecting rake 21 provided along the line.

In this example, black liquor was used as the diluent, a certain number of polyethylene grains and polypropylene grains were mixed into the supply knot, and the removal efficiency of lightweight foreign matter was measured.

The removal efficiency of lightweight foreign matter by this method is 99.4%
It was hot.

[Brief explanation of drawings]

FIG. 1 is a schematic diagram showing an embodiment of the present invention, and FIG. 2 is a sectional view of the separation device. 1...Liquid tank, 2...Liquid pump, 3...
Seed pump, 4...Head box, 5...Janson screen, 6...Knot blower, 7...
Head tank, 8... Separation device, 9... Chute, 10... Chip conveyor, 11... Chip pin, 12... Dilution water and knot supply port, 13
... Rake fulcrum, 14 ... Baffle plate, 15 ... Light foreign matter collection device, 16 ... Tray, 17 ... Partition plate, 18 ... Diluted liquid outlet, 19 ... Drive device,
20...Eccentric cam, 21...Rake for collecting knots.

Claims (1)

[Claims] 1. The knots separated from the pulp after cooking are supplied to the separator 8 together with a diluent, and the separated and floated lightweight foreign matter and the light foreign matter floated by the action of the knot recovery rake 21 are separated and floated. is removed from the tray 1 by the lightweight foreign matter collection device 15 installed at the top of the separation device 8.
6. A device for separating lightweight foreign matter. 2 A knot and a diluent supply port 12 are attached to one side of the separation device 8, a baffle plate 14 is provided in front of the supply port 12, and a baffle plate 14 is provided at the top, opposite to the flow direction of the liquid for collecting floating lightweight foreign matter. Reticular scraping board 2 moving to
2, a tray 16 for receiving the collected lightweight foreign matter, a diluted liquid discharge port 18, and prevent light foreign matter from flowing out to the diluted liquid discharge port 18 and re-mixing into the knot after separating the light foreign matter. A rake 21 is provided to collect the knots that have settled along the oblique bottom 23 extending from the bottom near the front of the baffle plate 14 to the chute 9, and a chute is provided at the tip for discharging the knots. 9. A device for separating lightweight foreign matter, characterized in that it is provided with a.