CS248571B1 - The method of obtaining fibers from waste water from pulp mills and paper mills and the equipment to perform them - Google Patents

Abstract

The subject method solves the problem of recycling fibers that enter the wastewater during pulp production. Its essence lies in the fact that the wastewater is thickened, its consistency is adjusted, sorted, fractionated, while the long-fiber fraction is thickened and the short-fiber fraction together with the effluents is thickened and drained. The equipment used to perform this method consists of a settler, a consistency regulator, an overflow tank, a vibrating screen, a mixing tank, a screen with a sieve basket, a battery of vortex screens, a fractionator, a thickening drum, an overflow tank, an effluent tank, a secondary sedimentation stage, a thickening press and a belt conveyor. The method and equipment can be used to recover fibers that are used for the production of cardboard and paperboard.

Description

The present invention relates to a method for recovering fibers from cellulosic waste water and paper mills in order to reuse a portion of the waste fibers into paper and board production,

In the production of pulp, paper and board, the quantity of Italians is in the range of 2% of the production volume · The sludge leaving the production is very diluted, has a consistency of 500 to 1000 mg / l and contains a mixture of fibers, *

In most cases, the sludges are disposed of after dumping to landfills or by incineration. The methods of using paper sludge for non-paper production are also known. production of composts with the addition of paper sludge, adding sludge to the mixture in the manufacture of bricks or building insulation materials, adding sludge to the feed mixture, etc. · However, these methods are also basically only liquid sludge ·

For example, Soderhjelm in Svensk Papperstidning 81,

No · 4 s · 110-113 recommends the use of low-sludge sludge to improve soil and high-sludge sludge, especially in building materials ·

There are also known ways of using sludges for paper production, eg · to lower-value paperboard · In this case, however, the accompanying feature of sludge use is deterioration of product quality, reduction of carton machine performance in discharge press and drying parts. has only a very small part of paper and board production ·

Said drawbacks of the technologies used so far are remedied by the method of recovering waste water fibers according to the invention, which is characterized in that the waste water is thickened in the primary settled stage of the waste water treatment plant, it is adjusted to 0.5 to 1% by weight. On the sorters with circular openings or slots and on the swirl sorters they are sorted, the sorted suspension is sent to a fractionation machine where it is divided into a short-fiber and long-fiber fraction, the long-fiber fraction is thickened and used to return to production and shortly. fibrous, together with screening separators, is concentrated in a secondary sedimentation stage, drained and treated or disposed of as sludge *

The principle of the apparatus according to the invention is that it consists of a primary settler for the cleaning of waste water, the outlet part of which for concentrated sludge is connected via a consistency regulator to an overflow tank and a vibrating screen, where the outlet part for good substance is connected through a stirred tank , a sewage sorter and a sorter battery with a fractionator which is coupled to a thickening drum for the long-fiber fraction and the paper machine centralization center. The discharge part of the vibrating screen is connected to the belt conveyor for pressed sludge and the discharge part of the screen with sewing basket, the discharge part of the swirl separator battery, the part for short filament discharge from the fractionator and the overflow tank is connected through the a reservoir with a secondary sedimentation stage, wherein the portion of the filtrate of the thickening drum to the long fiber fraction is connected via the overflow reservoir via a consistency regulator to the piping between the primary settler and the overflow reservoir and the secondary sedimentation stage is connected to the thickening press and the primary settler.

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The fractionated and sorted long fiber portion contains practically only long, easily dewatered and solid fibers which can be returned to the production process without adversely affecting the product quality or the performance of the paper machine. from screen separators goes to secondary thickening stage and liquidation, or non-paper processing, is mostly a mixture of short debris fibers, mucilages and kaolin *

The amount of fibers obtained is 30 to 50% of the total sludge *

The attached figure shows an example of the arrangement of the devices in the technology line according to the invention.

The sludge sludge is fed to the primary settler 4 of the sewage treatment plant * The clarified water from the primary settler χ is led back to the production plant. mm * Separate non-paper ingredients such as * wood, cloths, plastics foils, etc. * from the vibratory screen 4 are conveyed to a conveyor belt (extruded sludge) and screened sludge into a mixing tank 4 on a sewage basket £ which has passed through the screen of the screen 6 is guided to the battery of the swirl screen 7, the discharges from the screen 6 which contain small impurities are fed to the discharge tank * On the battery of the swirl screen 6 ^, small inorganic contaminants such as * sand, small chips and leave the last step fill into the reservoir (at Dobplýu / řiv »Good substance from the battery of swirl separators 7 is fed to the frsicoionator 8« Long fiber portion

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The short-fiber fraction from fractionator 8 containing fiber fragments, mucilaginous fractions and kaolin is fed to the tank / discharges. A mixture of fillers from the sorters 8 and the short-fiber fraction from fractionator 8 and the overflow of the filtrate from the overflow tank 10 is pumped to the secondary sedimentation tank. A portion of the filtrate from the thickening drum 6 is pumped as dilution water from the overflow tank 10 to the consistency regulator 2.

The sludge 12 is fed to the primary settler 1. The sediment from the thickener 13 is concentrated on the thickening press 13 and conveyed to the densified sludge dump. The filtrate from the thickening press 13 is led back to the secondary 12, long fiber portion. from fractionation and sorting, pumped at the paper machine's centralizing station, contains predominantly long fibers with a grinding degree of about 25 ° SR »

Thickened sludges in the landfill contain non-paper admixtures such as wood pieces, rags, plastic foils, etc., inorganic admixtures such as sand, kaolin etc. · and small fiber fragments ·

The quality of the obtained long fiber portion is approximately the same as that of the primary fibers used on the paper or board machines in the plant.

In this way, an economic benefit is obtained by returning usable fibers back to production while maintaining fiber quality comparable to the raw material, while at the same time substantially reducing the volume of sludge for further processing into non-paper production or disposal.

Claims (2)

SUMMARY OF THE INVENTION A method for obtaining fiber from waste water and pulp waste, characterized in that the waste water is thickened by the admixture of Acotin thipine waste wastes. f is adjusted to a consistency of 0.5 to 1% by weight, and is then screened and pulverized into a long-fiber and short-fiber fraction, whereby the long-fiber fraction is concentrated and used to produce a short fiber composition with it is concentrated by evaporation in a secondary sedimentation stage, draining off. elebo alcLvidu is ύ, ί, ο ί.4.Ιγ » 2. A device for obtaining fiber from waste water and paper waste water, characterized in that it comprises a primary settler (i) for cleaning waste water, the outlet portion of which is connected to the overflow regulator (2) for thickened sludge. a reservoir (3) and a vibrating class (4), wherein the good substance exit section is connected by a shunt tank (5), a sewed-sieve sorter (6) and a swirl sorter battery (7) with a fractionator (8), is coupled to a thickened drum (9) and a misfed paper machine center, wherein the spool portion (4) of the vibratory sorter (4) is coupled to the belt conveyor (14) and the scrubber portion (6) to the sieve basket; * the swirl sorter battery (7) »the short-fibrillated fraction of the fracoionator (8) and the overflow of the overflow tank (10) are connected by a filler of the filler vessel (11) to the secondary t / s and xov.0 wq (12), wherein the filtrate drainage portion of the thickening drum (9) is connected by the overflow tank (io) through the middle of the consistency regulator 248 871 (2) to the line between the primary settler (i) and the overflow tank 0} and the secondary va (12) is connected to a thickening press (13) and a primary settler (i) · 1 drawing