DE2339591C2 - Process and system for processing waste paper - Google Patents

Description

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^ J ^ ⁰ _ier ^g _processing by means of flotation eruie λ.ρ _{V f} , _the process: This has been followed so far η g ^ ^ ^ "^ ^^^

wires **? _Require chemicals, mostly

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large heavy parts were eliminated _ffsortierer floating from one ™™ L ^ impurities _to ^U. In a ^U ^ ^SI _no effect Mahlgradsteigerung f ",, _t e the fabric was deflaked. After de-stippling, wuraeuci ο. · The flotation system was fed into the material in my hotation system

3 Method according to one of claims 1 and 2, characterized in that the noted Suspension thickened in a known manner and the mechanical

however, in addition to the fact that the mea-

^^^^ S to be eliminated. Also there are ETwS ₈ S of recycled paper

^^ rin ^^ pSi, thereby characterized in that the waste paper by adding a chemical solution in the ratio paper to Solution of about 1: 1 pretreated and only afterwards introduced into the screw conveyor (6) ^

^W1 5 / Method according to Claim 4, characterized in that the waste paper torn into small pieces is pneumatically transported through a cyclone (3) in

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preparation of ^ ^A Ä ^e
reclaimed fabric

^ StenEinsatz ver a wide insert

fj% £ Zr solved by the method according to the invention according to claim 1

The focus of this process »is the dissolution of the waste paper in the snail and in that

^ ArfSe »r5u of the proceedings

according to claim 1 to 3, characterized by a screw conveyor (6) with a spray device (7) for feeding the chemical solution, a reaction tower (8) with a device for feeding dilution water (10, 11) into the area of the discharge opening, known per se Cleaning, (13) sorting, (15) and deflaking devices (18) and a flotation plant (19)

7. Plant according to claim 6 for performing the method according to claim 4 and 5, characterized in that a pneumatic conveyor (2) for transporting the torn waste paper and a cyclone (3) with a spray device (5) for supplying the chemical solution, the screw conveyor (6) are preceded _by ⁵

60

The invention relates to a method for processing waste paper by adding chemicals, by cleaning, sorting, deflaking and by floating in a flotation plant.

One of the main problems in recycling waste paper is the removal of printing inks. For this purpose, two essentially have been resolved. The screw transports the waste paper and mixes it with the chemical solution. Defibration should be avoided. In the reaction tower, irr ^^ ^lchem * ^e ^ paper ^{consistency-e} ^ prechend d _e r _TO given Chemikahenlosung more than 12 "/" bet Agu "" 8t d 'chemical Auflosereaktion, the Verwe.lze.t be set depending on the application For further transport and for the subsequent processing stages, the suspension is then appropriately diluted with water.

In addition to the advantage of a; gentler treatment of the waste paper is due to the higher chemical concentration a stronger reaction with that Waste paper. This is especially true for dyeing. The chemicals in a higher concentration act directly on the printing ink, as the paper bandage is still preserved. This also causes the detachment of firmly adhering printing inks - such as offset printing - and harder to dissolve printing ink binders such as asphalt pitch. Accordingly If the same chemicals are used, better results will now be achieved, or if the use is reduced, the obtained the same results. There is also a Energy savings, wed been found to be one Heat supply for the dissolution no longer required is.

It was also found that this marriage

mixed dissolution in the thick matter range due to the higher chemical concentration a very good dissolution of the waste paper is achieved, but foils, latex etc. are not attacked from now on, so that they can later be eliminated more easily. A significant advantage is that the waste paper processing can now take place continuously.

A preferred consistency range which gives good results is specified in claim 2.

By recycling the water obtained during thickening according to claim 3, the Water consumption kept low and wastewater problems avoided.

By pretreating the waste paper according to claim 4, a better digestion is achieved and this improves the result even further.

Claim 5 shows a simple and economical pretreatment process for this purpose.

In claims 6 and 7 are systems for ao Implementation of the method according to the invention shown.

A system for carrying out the method according to the invention is described below, from which further features according to the invention emerge. This system is only shown schematically in the figure.

The waste paper to be processed is fed into a shredder 1, a so-called shredder, from where it is blown into a cyclone 3 via a fan 2 after it has been shredded. In the cyclone 3, the waste paper is separated from the air. From a line 4 an alkaline chemical solution in a weight ratio of 1: 1 is injected into the cyclone 3 via a spray nozzle 5, to which water glass and peroxide are added to lighten the substance and destroy soluble dyes. The solution also contains oleic acid as a wetting and flotation aid, which is already saponified in the alkaline range. Calculated on the dry weight basis, the addition is expediently 1.5 to 2% sodium peroxide, 3 to 4% water glass and 0.8 to 0.9% oleic acid. Instead of sodium peroxide, it is also possible to use the equivalent amounts of NaOH and H ₂ O ₂ . The detachment of the printing inks can be supported by adding a small amount of detergents or surfactants, e.g. B. polyethylene oxide adducts of fatty alcohols and fatty acids, alkylphenol, polyglycol ethers or esters, alkyl sulfonates.

From the cyclone 3, the waste paper arrives in a screw conveyor 6, which is also fed through spray nozzles 7 from line 4 the chemical solution now in the ratio of waste paper to chemical solution 1: 4 is added.

The waste paper interspersed with the chemical solution is conveyed by the screw conveyor 6 into a reaction tower 8, in which it remains for about 2 hours at a consistency of 16 to 20%. In the lower area of the reaction tower a circulating propeller 9 is arranged, in the intake area of which dilution water is added via lines 10 and 11. The thick material mixture of chemical solution and waste paper, which lies like a column above the circulating propeller 9, is diluted by the ducts 10 and 11 by means of the circulating propeller 9, breaks down into individual fibers and can thus be discharged from the reaction tower 8. A pump 12 conveys the suspension, which now has a consistency of 4.0 to 5.0% dry weight, into a hydrocyclone 13, in which the heavy parts are separated out. The accept outlet 14 of the hydrocyclone 13 is connected to a vibrating sorter 15, in which floating impurities are separated. Via an intermediate vat 16 and a pump 17, the suspension is passed into a deflaker 18, in which no increase in the degree of grinding should take place. After deflaking the pulp flows into the flotation unit 19 where it on by a further dilution water supply via a line 20 to a density% 'is about 0.8 to 1.0 ⁰ Zo is atro diluted. The flotation plant has a conventional structure. It essentially consists of two sections, a so-called primary stage 21 with several cells and a secondary stage 22 with two cells. The primary stage is used to purify the starting material, and its accepted material goes through the outlet line 24 to the further production. In addition to the dirt particles and some of the fillers, the waste (foam) from the primary cells also contains a proportion of fibers that is largely recovered in the secondary stage 2. The raw material of this stage is returned to primary stage 1 via return line 24 for further treatment. The foam from secondary stage 2 is removed from outlet 25. In the thickened state with a dry content of 35 to 45%, the foam can either be incinerated or taken to a landfill. The clear water resulting from further processing, when the substance is thickened, is returned to the reaction tower 8 as a circuit via the lines 10 and 11.

For this purpose, 1 sheet of drawings

Claims (2)

Claims: Ait r, i- 1. Process for recycling waste paper by adding chemicals, by cleaning, ο sorting, deflaking and by floating m one Flotation plant, thereby marked.inet, that what was torn into small pieces: waste paper by a screw conveyor (6), in the for Dissolution of a chemical solution m at most 7.5 times the weight of the waste paper is introduced, transported, then into a Reaction tower (8) for further unlocking, with a consistency of at least 12 · / ·, then for cleaning, sorting »5 and deflaking the fabric diluted with water and finally in a flotation plant (19) in is known to float. 2. The method according to claim 1, characterized in that that the waste paper with a material density of 16 to 20 «/» in the reaction tower (8) entered and treated there for about 2 hours drive known, namely the removal of printing inks by washing out or by flotation. Compared to the flotation process, the washing-out process has, from an economic point of view, some post-; "" ^SV ^ _{ez B large} fiber losses and the accumulation of _{dirty water from dksem} erhemicner _di waste paper processing by means of FIo- and