DE4119303C2 - - Google Patents

Description

In many productions and preparation processes as well as in the collection of Residues may fall a. Types of waste from mechanical connections of lumpy metal parts, polymers, color pigments and mostly others inorganic and organic additives such as fillers, plasticizers etc. exist. The metals are often environmentally hazardous heavy metals such as e.g. B. with copper cable scrap. Without further processing, there would have to be Waste is disposed of as special waste, which means high disposal costs would and in addition the waiver in such waste still contained, in itself recyclable components such. B. the Heavy metals, the polymers and possibly also the plasticizers.

Various methods have therefore been proposed, firstly, to be independent only the bulk of the type of non-metallic parts Separate (heavy) metals from the waste, e.g. B. by crushing / Shredding the waste into particles so small that all or most of it particles consisting of metal and thus specifically heavier mechanically separated from the particles containing little or no metal can be, e.g. B. by sighting.

On the other hand, in the event that the non-metallic components of the waste are sufficiently meltable because they e.g. B. contain thermoplastics, processes have been developed, the metals and the melted or only warmed to softening portions of the Separate scrap mechanically, this separation process often only after shredding / shredding of the scrap is possible. So that the Scraps are broken down into a portion that has a lot of metal and only a little of the polymer / aggregate mixture and in a proportion that the Most of the thermoplastics and additives and hardly any Contains metal residues.

Before the metal-containing portion of one processed by such a method Scrap can be processed as a recycling raw material the still adhering non-metals are removed, e.g. B. by thermal Decompose the organic components and then mechanically remove them of inorganic substances.

The mixture separated from the metal, melted or plasticized, predominantly consisting of thermoplastics, plasticizers, color pigments, inorganic additives, such as. B. rock flour, can either directly as a recycling raw material for inferior products such as B. road posts, Base plates, bank fortifications, are used or only in very limited proportions as an additive / admixture in production higher quality plastic products. The mixture is particularly disturbing here the different color pigments of the original products from which the mixed scrap has arisen, which usually results in a strong dark brown / black hue of that obtained by such melting processes Recycled material.

Methods are also described in which the organic substances be decomposed by pyrolysis to such an extent that they are drawn off in gaseous form can be, so that only the metal parts and possibly the inorganic additives remain in the pyrolysis vessel.  

Methods for removing lacquers / paints are also described, at which either (hot) acid or alkali solutions are used with whose help the lacquer / paint layers are destroyed or dispersed. Or an organic solvent, e.g. B. methylene chloride used in the the varnish / paint layers swell and then as flakes from the metal parts can be replaced, e.g. B. by a high pressure jet wash. Act it is a pure varnish, then this can be done by another method first in an organic solvent, e.g. B. methylene chloride, dissolved and then, if necessary after distilling off part of the solvent, as a recycling chemical can be used again.

None of these methods can separate the metal parts Multi-component mixture of (chlorine) hydrocarbon polymers, if necessary Plasticizers, organic and inorganic color pigments, and any soluble ones Dyes and possibly other, especially inorganic fillers and additives disassembled directly after a dissolving process be that the more valuable components are obtained separately and the rest is more environmentally friendly to dispose of than the original multi-component mixture.

There is therefore an economic and ecological interest in a process for separating waste from a lumpy mixture (Heavy) metal parts, soluble (chlorinated hydrocarbon-containing) polymers, Plasticizers as well as organic and inorganic colorants and additives consist in

• - a fraction that only contains the metals without any residues adhering to them of organic material or of inorganic fillers,

and depending on the type and proportion of plasticizers and, if applicable, also the soluble dyes and auxiliaries either in

• - two other groups, one of which
  • - Contains the (soluble) polymers, in particular those made from chlorinated hydrocarbons, and possibly also the plasticizers in the highest possible purity, in particular with no proportion of color pigments or inorganic additives, and the lowest possible proportion of non-pigment-form, ie homogeneously distributed, dyes, and the other
  • - Contains the color pigments, inorganic additives and possibly also the plasticizers and the non-polymeric organic constituents of the waste, but does not contain any (heavy) metals and in particular no chlorinated hydrocarbons, and is therefore easier to dispose of than the starting material.
• - or in three further fractions, one of which
  • - contains only the most possible color, plasticizer and additive-free polymers, the second
  • - Contains the least colorable plasticizer phase and the third
  • - only the color pigments, which contain inorganic and organic, especially chlorine-free, non-polymers, and which is therefore also easier to dispose of.

Such a reprocessing process creates a process chain the (heavy) metals directly as a recyclable, high-quality raw material for the known metallurgical / electrolytic processes for further processing and at the same time the soluble (thermoplastic) polymers and possibly also the plasticizers as compared to the known ones known  Melting / dissolving processes much better recyclable raw materials for the production of high quality plastic products. The Remaining waste remains no longer contains recyclable materials (heavy) metal-free, and it also contains no, possibly chlorinated, polymers, e.g. B. polyvinyl chloride, so that it can be disposed of much more easily, e.g. B. in an incinerator, without risk of synthesis of multiple chlorinated pollutants such as dioxins / furans and without the occurrence of heavy metals Ashes.

It has been found that the task can be fulfilled if the lumpy scrap of metal parts, (thermoplastic) polymers, inorganic and organic dyes and fillers with the help of a possibly multi-stage Dissolving and precipitation process in the desired recyclable Components and the residual residue that is easier to dispose of becomes.

If necessary, the waste must first be washed with water, if necessary with the addition of suitable detergents, with subsequent drying of any. adhering dirt and / or oil / fat as well as largely from all Moisture residues are freed.

It is the case with elongated, folded or intertwined waste parts also advantageous that the waste is crushed so far that the Individual parts no longer get caught mechanically to form larger agglomerates / can solidify, d. that is, e.g. B. the length of cylindrical waste parts how electrical cable scrap is on average <20-30 of the diameter.

It turned out that this scrap, which had been pretreated in this way, failed only the soluble (chlorinated hydrocarbon-containing) polymers with the help of suitable, dissolve unlimitedly with water-miscible solvents, but that it moves by intensive mechanical mixing and moving against each other the lumpy pieces of waste during the dissolving process z. B. with help of stirring blades that pass through the mixture also succeeds all organic and inorganic dyes and additives that are common in such scrap after adequate pre-cleaning are present in the homogeneous solvent-polymer mixture either also to solve or to disperse so finely that pure metal parts without firmly adhering residues.

This dissolving / dispersing process can be carried out in addition to mechanical removal already dissolved or softened, non-metallic components accelerate considerably by the above-mentioned mixing, that the solvent is preheated as high as possible (e.g. up to near the boiling point) fed and also heated the container during this process becomes. It is natural to avoid pollutant emissions necessary, a sufficient in the pressure compensation line of the container large condenser connected to a sufficiently cold coolant built in to condense the resulting solvent vapors and again to be able to return to the release container.

It was also shown to accelerate the dissolving and dispersing process and in particular also the following mechanical separation of the particles dispersed in the solution and also those that may still be required adsorptive separation of dissolved dyes is useful, more To use solvents than is only required for dissolving / dispersing.  

To reduce the effort involved in the and cleaning steps, it is then advantageous to use this excess amount of solvent separate again before the first precipitation process, e.g. B. by a Evaporation.

The addition of an excess of solvent also has the advantage that the Metal parts by simply rinsing off any paint and paint still adhering Filler particles can be freed. It is not a pressure jet wash required.

By stirring and applying heat and a corresponding excess of solvent it succeeds in the entire dissolving / dispersing process z. B. for Perform copper cable scrap in <30 minutes, making it a economically interesting cycle time for a batch process is made possible.

It has also been found that the overall process is particularly favorable and is environmentally friendly when the solvent is mixed with water is infinitely miscible, e.g. B. tetrahydrofuran because so

• - Small water residues, which may still be on the pretreated scrap pieces adhere, interfere less with the dissolving / dispersing process;
• - The adhering to the metal parts after the last rinsing process and no polymer or dispersion containing organic solvents Water can be rinsed off;
• - Also in the filter / centrifugation processes to be described to separate the dispersion, possibly the activated carbon and the polymers after rinsing with organic solvent as the last rinsing step then water can be used;
• - In the process step to be described for separating the Polymers or other dissolved components water as a precipitant can be used;
• - In a multi-stage precipitation process for selective precipitation of the polymer and other dissolved components in the last stage, water can be used.

If sufficient solvent is added in the dissolving / dispersing step, e.g. B. in the treatment of copper cable scrap ∼ 10 to 15 times Weight of the total non-metallic content in the scrap, then it succeeds in the treatment of scrap, which with strong coloring plastic parts, especially with black ones, Surprisingly, the mixture running out of the dissolving container dispersed, d. H. insoluble, organic and inorganic color and aggregates mechanically before further processing the solution to be largely separated so that a low-color solvent-polymer mixture arises, e.g. B. by centrifuging, filtering, and (possibly only as a post-stage) also by ultrafiltration with solvent-resistant membranes and such large pore size that the dissolved polymers can pass through.

The resulting residue after this mechanical separation process remaining residues of the solvent-polymer solution can then be used analogously for the rinsing processes of the metal parts in the dissolving tank, if necessary in several Processes with solvent and / or (as the last rinsing step) with water removed will. This gives you a solvent, chlorinated hydrocarbon and (heavy) metal-free residue from the non-soluble and non-metallic Components of the refurbished scrap, accordingly is easier and cheaper to dispose of.  

It was found that from the particle-free, i.e. H. homogeneous solution of solvent, Polymers, plasticizers and, if applicable, soluble dyes and additives the polymers are separated by precipitation in an analogous manner as in the separation of the polymer in the known production of polymer from monomer by polymerization in the solvent with subsequent Precipitating and filtering / centrifuging the resulting dispersed Polymer particles.

If the scrap used is sufficiently uniform, e.g. B. electrical cable scrap, especially from the (new) installation, and / or the solvent-polymer solution is sufficiently poor in color, d. i.e. when the solubility of the staining Components in the scrap is sufficiently low to get through (one-step) felling z. B. only with water a sufficiently uniform and poor in color Recycling raw product from precipitated polymers, plasticizers and other soluble additives, if necessary, which after removal of the Residues of the solvent and water from the precipitated and separated Particles analogous to the previously described rinsing and drying steps for the production of higher quality plastics can be used.

If that obtained by felling only with water and appropriate after-washing Mixture of polymer, plasticizers, soluble colors and other additives are not yet uniform enough or too strongly colored is to be able to use it as a high-quality recycling material the quality of the recycled polymer can be improved. It was found, that two process steps are suitable for this, individually depending on the requirement or both can be used: multi-stage, selective felling and adsorptively removing the dissolved dyes before precipitation.

In the event that the solution after separating the dispersed scrap parts still has too high a non-polymer content to make a higher quality one Separate the recycled polymer from the solution by one-step precipitation Being able to do a multi-stage precipitation to a purer recycled polymer to lead. It has been found that for selective felling the Polymeric alcohols are suitable. This is done by a first precipitation step preferably to displace the polymers as a dispersion from the solution and the other components, especially the plasticizers, in the solution hold. It has been found to be particularly advantageous to use alcohols or their To use mixtures that:

• - are miscible with water or at least partially miscible and
• - In their boiling point as much as possible from that of the solvent and if necessary, also distinguish it from water in order to describe it below (multi-stage, possibly also hetero-azeotropic) rectification process to be able to separate from the mixture in the most energy-saving manner; e.g. B. in tetrahydrofuran as a solvent butanol as a selective precipitant, if the plasticizers are subsequently precipitated by water.

In the event that the proportion of recyclable in the remaining solution Plasticizers high and the proportion of water-insoluble, coloring or otherwise disruptive components, possibly only after that described below Adsorption step, is small enough, it is appropriate to this plasticizer phase by precipitation with water, filtering / centrifuging, rinsing and separate drying if necessary.  

It was also unexpectedly found that in the event that Par particle-free solution of solvents, polymers, plasticizers and possibly others soluble components still contains too much soluble dyes, so that the polymer precipitated therefrom (possibly selectively) because of its color These color components are not to be used as a valuable recycling raw material are to be removed from the solution by an adsorption step. Normal water cleaning activated carbon has proven particularly suitable proven that with the solution analogous to the known, discontinuous What Water cleaning process introduced into the solution and then after about 15-30 Minutes is filtered again. With a larger content of soluble, disruptive Dyes can be saved in several stages with Ge to save activated carbon counter current flow of solution and coal.

It was also found that the filtered, dye-loaded activated carbon together with those first filtered out of the solvent-polymer mixture Particles, e.g. B. the color pigments to separate the adhering solvents and residues of precipitant can be treated in one rinsing process; With the possibility of then recovering the latter (by distillation).

Adsorptive removal of the dissolved dyes before filtering / Centrifuging the particles dispersed from the scrap into the solution, the z. T. much finer than the activated carbon particles is possible. The activated carbon can also be used as a filter aid in the separation of the fine suspension particles work, and you save yourself one at the same time mechanical separation step, but this is done until the solution is decolorized more coal is needed for the same residual color values.

The remaining solution of solvent (e.g. tetrahydrofuran), possibly organic Precipitants (e.g. alcohol or alcohols) and possibly non-recycling worthy plasticizer phase and water can then be used in the usual way e.g. B. also by distillation and with partial solubility of solvent / precipitant in water heteroazeotrope are largely separated again so that one has enough pure components for dissolving / dispersing, selective cases if necessary and overall cases. Of course, this must be done in this separation process Proportion, e.g. B. as a bottom product from the last workup stage, and by fresh substances are replaced so that there is no disruptive enrichment, e.g. B. from soluble high boilers comes.

Claims (7)

1. A process for the separation of metals, low-color polymers, in particular thermoplastic (chloro) hydrocarbons and possibly low-color plasticizer phase from lumpy waste mixtures which contain additives such as inorganic fillers, color pigments and dyes which are soluble or insoluble in the solvent, characterized in that

• - if necessary, after comminution in a first step in a dissolving container, the soluble, organic polymers are dissolved in an organic, water-immiscible solvent with mechanical mixing of the lumpy waste with excess solvent and the insoluble additives are dispersed in this solution,
• the lumpy metal parts are freed from residues of the solvent mixture and dispersed particles still adhering after the dispersion obtained has been discharged from the dissolving container in a subsequent one- or multi-stage washing and drying process,
• the particles still contained in the dispersion are separated from the homogeneous solution in a mechanical separation process and are freed from solvents and polymers by a washing and drying process,
• - The dissolved polymers are selectively precipitated by adding one or more stages of an organic, at least partially water-miscible precipitant, or the dissolved polymers and plasticizers are precipitated by adding one or more stages of water, mechanically separated and converted into a recyclable polymer by a washing and drying process. Raw material are transferred
• - The solvent and the precipitant are separated from the remaining liquid mixture and recycled for dissolution / precipitation.

2. The method according to claim 1, characterized in that that tetrahydrofuran is used as solvent. 3. The method according to any one of claims 1 and 2, characterized in that alcohols or mixtures thereof are used as selective precipitants. 4. The method according to any one of claims 1 to 3, characterized in that the solvent, in particular preheated to near the boiling point is added and / or that the dissolving container during the dissolving / Dispersing process is heated and that vapors formed in one The condenser is deposited and returned to the container will. 5. The method according to any one of claims 1 to 4, characterized in that the dispersion before or after the mechanical separation of the suspended Particles and adsorptively cleaned before the precipitation of the polymers.   6. The method according to any one of claims 1 to 5, characterized in that that the plasticizer after the mechanical separation of the previously precipitated Polymers in particular are precipitated with water.   7. The device for carrying out the method according to claim 1, characterized in that in a lying, cylindrical container with heating possibility through the wall

• - A known coaxial stirrer shaft with stirrer blades is arranged, which in one direction of rotation promotes the finished metal parts to an ejection opening with a closure that is as flush as possible with the cylinder wall at the bottom of one end of the container and the drive further a constant change of direction with an angle of rotation of ∼180 ° enables
• - That at the bottom or top of the container further openings / sockets, each with a closure, such as filler opening, drain opening with strainer and vapor extraction, are attached.