DE19519865C2 - Process for sorting plastics from a mixture of particles of different plastics - Google Patents

Process for sorting plastics from a mixture of particles of different plastics

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Publication number
DE19519865C2
DE19519865C2 DE1995119865 DE19519865A DE19519865C2 DE 19519865 C2 DE19519865 C2 DE 19519865C2 DE 1995119865 DE1995119865 DE 1995119865 DE 19519865 A DE19519865 A DE 19519865A DE 19519865 C2 DE19519865 C2 DE 19519865C2
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DE
Germany
Prior art keywords
plasma treatment
mixture
flotation
particle mixture
plastics
Prior art date
Legal status (The legal status is an assumption and is not a legal conclusion. Google has not performed a legal analysis and makes no representation as to the accuracy of the status listed.)
Expired - Fee Related
Application number
DE1995119865
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German (de)
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DE19519865A1 (en
Inventor
Bjoern Dipl Phys Stueckrad
Karsten Dr Loehr
Current Assignee (The listed assignees may be inaccurate. Google has not performed a legal analysis and makes no representation or warranty as to the accuracy of the list.)
Daimler AG
Original Assignee
Daimler Benz AG
Priority date (The priority date is an assumption and is not a legal conclusion. Google has not performed a legal analysis and makes no representation as to the accuracy of the date listed.)
Filing date
Publication date
Priority to DE4427718 priority Critical
Application filed by Daimler Benz AG filed Critical Daimler Benz AG
Priority to DE1995119865 priority patent/DE19519865C2/en
Priority claimed from CH02247/95A external-priority patent/CH689380A5/en
Priority claimed from JP21830695A external-priority patent/JP2797072B2/en
Publication of DE19519865A1 publication Critical patent/DE19519865A1/en
Publication of DE19519865C2 publication Critical patent/DE19519865C2/en
Application granted granted Critical
Anticipated expiration legal-status Critical
Expired - Fee Related legal-status Critical Current

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Classifications

    • BPERFORMING OPERATIONS; TRANSPORTING
    • B03SEPARATION OF SOLID MATERIALS USING LIQUIDS OR USING PNEUMATIC TABLES OR JIGS; MAGNETIC OR ELECTROSTATIC SEPARATION OF SOLID MATERIALS FROM SOLID MATERIALS OR FLUIDS; SEPARATION BY HIGH-VOLTAGE ELECTRIC FIELDS
    • B03BSEPARATING SOLID MATERIALS USING LIQUIDS OR USING PNEUMATIC TABLES OR JIGS
    • B03B1/00Conditioning for facilitating separation by altering physical properties of the matter to be treated
    • BPERFORMING OPERATIONS; TRANSPORTING
    • B03SEPARATION OF SOLID MATERIALS USING LIQUIDS OR USING PNEUMATIC TABLES OR JIGS; MAGNETIC OR ELECTROSTATIC SEPARATION OF SOLID MATERIALS FROM SOLID MATERIALS OR FLUIDS; SEPARATION BY HIGH-VOLTAGE ELECTRIC FIELDS
    • B03DFLOTATION; DIFFERENTIAL SEDIMENTATION
    • B03D1/00Flotation
    • B03D1/02Froth-flotation processes
    • BPERFORMING OPERATIONS; TRANSPORTING
    • B29WORKING OF PLASTICS; WORKING OF SUBSTANCES IN A PLASTIC STATE IN GENERAL
    • B29BPREPARATION OR PRETREATMENT OF THE MATERIAL TO BE SHAPED; MAKING GRANULES OR PREFORMS; RECOVERY OF PLASTICS OR OTHER CONSTITUENTS OF WASTE MATERIAL CONTAINING PLASTICS
    • B29B17/00Recovery of plastics or other constituents of waste material containing plastics
    • B29B17/02Separating plastics from other materials
    • BPERFORMING OPERATIONS; TRANSPORTING
    • B29WORKING OF PLASTICS; WORKING OF SUBSTANCES IN A PLASTIC STATE IN GENERAL
    • B29BPREPARATION OR PRETREATMENT OF THE MATERIAL TO BE SHAPED; MAKING GRANULES OR PREFORMS; RECOVERY OF PLASTICS OR OTHER CONSTITUENTS OF WASTE MATERIAL CONTAINING PLASTICS
    • B29B17/00Recovery of plastics or other constituents of waste material containing plastics
    • B29B17/02Separating plastics from other materials
    • B29B2017/0203Separating plastics from plastics
    • BPERFORMING OPERATIONS; TRANSPORTING
    • B29WORKING OF PLASTICS; WORKING OF SUBSTANCES IN A PLASTIC STATE IN GENERAL
    • B29BPREPARATION OR PRETREATMENT OF THE MATERIAL TO BE SHAPED; MAKING GRANULES OR PREFORMS; RECOVERY OF PLASTICS OR OTHER CONSTITUENTS OF WASTE MATERIAL CONTAINING PLASTICS
    • B29B17/00Recovery of plastics or other constituents of waste material containing plastics
    • B29B17/02Separating plastics from other materials
    • B29B2017/0213Specific separating techniques
    • B29B2017/0217Mechanical separating techniques; devices therefor
    • B29B2017/0248Froth flotation, i.e. wherein gas bubbles are attached to suspended particles in an aerated liquid
    • BPERFORMING OPERATIONS; TRANSPORTING
    • B29WORKING OF PLASTICS; WORKING OF SUBSTANCES IN A PLASTIC STATE IN GENERAL
    • B29KINDEXING SCHEME ASSOCIATED WITH SUBCLASSES B29B, B29C OR B29D, RELATING TO MOULDING MATERIALS OR TO MATERIALS FOR MOULDS, REINFORCEMENTS, FILLERS OR PREFORMED PARTS, e.g. INSERTS
    • B29K2033/00Use of polymers of unsaturated acids or derivatives thereof as moulding material B29K2035/00 takes precedence
    • B29K2033/18Polymers of nitriles
    • BPERFORMING OPERATIONS; TRANSPORTING
    • B29WORKING OF PLASTICS; WORKING OF SUBSTANCES IN A PLASTIC STATE IN GENERAL
    • B29KINDEXING SCHEME ASSOCIATED WITH SUBCLASSES B29B, B29C OR B29D, RELATING TO MOULDING MATERIALS OR TO MATERIALS FOR MOULDS, REINFORCEMENTS, FILLERS OR PREFORMED PARTS, e.g. INSERTS
    • B29K2055/00Use of specific polymers obtained by polymerisation reactions only involving carbon-to-carbon unsaturated bonds, not provided for in a single one of main groups B29K2023/00 - B29K2049/00, e.g. having a vinyl group, as moulding material
    • B29K2055/02ABS polymers, i.e. acrylonitrile-butadiene-styrene polymers
    • BPERFORMING OPERATIONS; TRANSPORTING
    • B29WORKING OF PLASTICS; WORKING OF SUBSTANCES IN A PLASTIC STATE IN GENERAL
    • B29KINDEXING SCHEME ASSOCIATED WITH SUBCLASSES B29B, B29C OR B29D, RELATING TO MOULDING MATERIALS OR TO MATERIALS FOR MOULDS, REINFORCEMENTS, FILLERS OR PREFORMED PARTS, e.g. INSERTS
    • B29K2069/00Use of PC, i.e. polycarbonates or derivatives thereof, as moulding material
    • BPERFORMING OPERATIONS; TRANSPORTING
    • B29WORKING OF PLASTICS; WORKING OF SUBSTANCES IN A PLASTIC STATE IN GENERAL
    • B29KINDEXING SCHEME ASSOCIATED WITH SUBCLASSES B29B, B29C OR B29D, RELATING TO MOULDING MATERIALS OR TO MATERIALS FOR MOULDS, REINFORCEMENTS, FILLERS OR PREFORMED PARTS, e.g. INSERTS
    • B29K2071/00Use of polyethers, e.g. PEEK, i.e. polyether-etherketone or PEK, i.e. polyetherketone or derivatives thereof, as moulding material
    • B29K2071/12PPO, i.e. polyphenylene oxide; PPE, i.e. polyphenylene ether
    • Y02W30/622

Description

The invention relates to a method for Sorting plastics from a mixture of particles different plastics according to the generic term of claim 1, such as from the U.S. Patent 4,046,677 is known to be known.

The effort to recycle the garbage reduction of plastics contained in the garbage gladly, has led to the plastic of the garbage collected separately and for recycling to be led. For this it is necessary to collectively plastic types contained in waste plastic separate. In this endeavor one has several Separation process developed.

Most of the separation processes used today are based on the use of density differences of the individual mixture components, for example the separation of plastics by means of floating-sink Separation or by means of cyclones / hydrocyclones (Al bert Bahr, Erzmetall 33, 1980, pp. 324-330). Such Processes fail with plastic mixtures whose Components have the same or similar densities. The highest possible reuse of art However, garbage requires that it be as pure as possible Separation of the mixture.

Another selection characteristic for sorting In addition to density, plastics are wettable speed of the plastic surface. This selection feature is used in the flotation by the crushed plastic mixture in a liquid (ex licher water) is suspended and there one Stream of rising gas bubbles (usually Air) is exposed. These gas bubbles are deposited speaking of the wettability of the mixture components selected them. Good wettability of the art fabric surface through the suspension liquid bad bladder attachment and vice versa Most of today's plastics are owned a naturally hydrophobic surface, that means she are poorly wettable by water, so store well Bubbles on and then swim to the liquid surface che on. A selective bladder attachment and thus one Sorting into a floating and a sinking Fraction requires a selective modification of the na door wettability of the plastic surfaces. Be standing methods for sorting plastics these surface modifications lead by flotation through chemical conditioning of art substances in the suspension liquid. In this Please refer to US Pat. Nos. 4,046,677, 4,132,633, 4,167,477, 5,120,768, CA-PS 2,073,951 or the EP 0 535 419 A1, which deals with flotations separation of individual plastics from different ones Groups of plastic mixtures deal and that there on required chemicals and treatment methods propose that.

So far, sorting using flotation was not necessary agile surface modification of the plastic parts So always wet with chemical conditioning achieved, d. h by adding interfacial active chemicals directly into the flotation cell. Out For economic and ecological reasons, the Flo tion liquid circulated. Usually must be in addition to that required for surface modification so-called pusher reagent another so-called Foamer reagent is added to the training to enable a stable foam. The Concentrations of both reagents decrease over time time through foam and plastic discharge. The un dependent regulation of both concentrations to one each because optimal level is difficult. Furthermore would need a ge for each type of plastic own set of reagents, namely pusher and Foaming reagent can be provided, but not is fulfilled for all types of plastic. Otherwise it is Find a new, selectively active reagent very time-consuming and expensive, at least when it is Selection effect should be sufficiently high.

The object of the invention is to overcome these disadvantages sides and the generic Ver drive to improve that less chemi Kalienarten, especially no trigger reagents be necessary and the adjustment of optimal flotation conditions gene is simplified and a flotation separation also such plastics is made possible, which so far has not been based on could be separated this way.

This task is based on the gat Process according to the invention by the characterizing features of claim 1 solved. There after the surface modification will be some time before the flotation dry using plasma treatment achieved. It is essential to adhere to a certain storage time in which the actual sorts selectivity of the plasma treatment automatically poses. Surface modification using plasma treatment achieved, only the foamer rea be introduced into the flotation liquid.

The regulation of this one concentration on one opti Male level is much easier.

Sorting by flotation is done by off use of the different wettability of the ver different mixture components by the flotations liquid. Most real plastic plastic mixes do not show sufficient differences in their wettability to sort using flota tion.

It is known that by means of plasma treatment any wettability of plastics turned on can be put. However, previous results show that the same treatment of different plastics only one for all varieties in a mixture even shift than to fanning out leads within a wettability scale. I.e. without Plasma treatment are all components of the Sample mixtures are distinctly hydrophobic, they store well Bubbles on and all float immediately. According to the Plas Ma treatment are all highly hydrophilic, they store no bubbles on and no mixture component floats. Surprisingly, it has now been found that the one set with the help of plasma treatment Wettability of the different mixture components changes at different speeds, d. H. that through the Plasma treatment caused wettability of Plastic surfaces for different plastics only remains effective for different long periods of time.

After a few days, a mixture component is again strongly hydrophobic while others are still very hydrophilic. Such Gemi flots can be sorted well using flotation.

For example, they become naturally hydrophobic that is, plastics that are not wettable by water Acrylonitrile-butadiene-styrene copolymer (ABS), styrene Acrylonitrile copolymer (SAN), polycarbonate (PC) and Polyphenylene oxide (PPO) by means of plasma treatment hy drophil, none of them are stored in a flotation cell  Air bubbles more and remain in the suspension liquid. The impact of plasma treatment however, the wettability of ABS is compared to on the wettability of the other plastics from short duration. ABS is like this after just a few days again hydrophobic and very well stored in the suspension ascending air bubbles during the other plastics are still extremely hydrophilic, thus do not attach bubbles and sink.

Using a mixture of ABS, SAN, PC and PPO and possibly other plastics the surface of the ABS can be plasma treated and mixture-specific aging period hydrophobic set above that of other plastics. In the subsequent flotation, the ABS is floated and can be applied as a foam product while the other plastics in the suspension liquid remain.

The plastics used are the aforementioned types of plastic, which by Shredding into a form capable of flotation the. The origin of the art used plays here substances don't matter. So z. B. foils, fibers, cables, Nonwovens, knitted fabrics or molded parts are used the.

The size and shape of the plastic used parts is not particularly limited. Because of Handling, especially the pumpability is the suitable size of the plastics used half of about 20 mm, preferably at 2-12 mm. In between it could be shown that the separation process with particles up to 100 mm in size ten length is feasible. The regarding the Trennver driving optimal particle size is material and Ge mix-specific and would have to be empirically opti be lubricated. This size of the art used substances is achieved in that the aforementioned Plastics through common shredding processes such as Chopping, cutting, chopping or tearing in Plastic parts of the size above are performed and optionally also as granules or schnitzel can be used for flotation. That ever shredding processes used is to be chosen on a case-by-case basis; the optimal choice depends on Degree of "growing together" of the composite parts.

The mixture of ABS and one or more of the The plastics mentioned above are used before flotation plasma treatment with regard to its wettability modified. The plasma is left at small plants - laboratory size - over a period of up to 60 seconds, preferably 5-10 seconds act on the plastic mixture. For larger systems on a pilot plant scale with a different plasma chamber mer and larger loading capacity (1.5 kg) good results at around 30 Pascal base pressure and 60 up to 120 seconds of treatment achieved suitable Process gases require an enrichment of art fabric surface with polar functional groups that Oxygen, nitrogen, sulfur or similar polarization containing elements (hydroxyl, carboxyl and / or carbonyl groups, esters, ethers, amines, amides, sul fonate or similar). Are polarized surfaces through polar suspension liquids (water or on ) well wettable, accumulate bad gas bubbles and are not floated.

The introduced polar functional groups represent an excited state of the surface and have a high steric mobility. After one substance-specific period, these are functional Groups in the energetically more favorable position under fold over half of the surface. This explains the substance specific, time-dependent change in wettability.

Suitable discontinuous plasma plasma for the polarization of the plastic surfaces are from surface activation and cleaning knows. Also continuously in a free atmosphere, i.e. H. in air or U. work under a special gas End treatment lines for a plasma treatment of substrates, which are also expedient in the present case have been put in by other research institutes already presented.

The investigations were mainly in the present case Lich with oxygen as a process gas in plasma treatment carried out and thus basically positive results made trips. Nitrogen is also for a plasma treatment in the same sense - d. H. discount of Wettability - like oxygen in plasma treatment applicable. A treatment of the plastic mixture argon plasma also leaves in the same Directional surface modifications, albeit to a lesser extent. A plas MA treatment of plastics with tetrafluorocarbons fabric increases the already high hydro as a rule phobia of plastics and therefore does not come seriously into consideration. A rapid, specific regression of the artificially increased hydrophobicity - this became all not examined - may also occur here and u. U. to a different kind of diversification with regard to Lead wettability through storage. It can be pleasant men that u. U. a certain material type of Plasma in plasma treatment for individual art substances of a mixture acts selectively; e.g. B. will report tet that a plasma treatment with noble gas plasma Ver triggers wetting reactions, these reactions se lective with regard to the molecular weight of polyols we like polyethylene (PE) and polypropylene (PP) ken.

Following the plasma treatment and after ei In a mixture-specific aging period, this will be Plastic mixture introduced into a flotation cell The plastics are in the cell in a polar - preferably aqueous - suspended solution. Usual The aqueous solution is usually water, but water, which salts, can also be used contains examples from the literature for salt water species, which are suitable for flotation purposes are sea water, Brine, bitter water (magnesia-containing water) such as also aqueous solutions, the halides and / or sul fate included.

The aqueous solution contains a flotation foam mer. This serves to train a viable one Foam layer and to reduce the bladder koa gulation and thus to the formation of a relatively schma len bubble size spectrum.

Suitable flotation foamers, such as those in the Litera are referenced

  • - Aliphatic and cycloaliphatic alcohols with 5 to 10 carbon atoms or
  • - Polyglycols with a molecular weight (Ge weight means) from 200 to 500, such as. B. Polyalkylene glycol (Flotanol® C7; manufactured by HO- ECHST AG) or
  • - Alkyl polyglycol ether with a molecular weight weight from 200 to 500 (Flotanol® D14; manufactured by HOECHST AG).

The concentration of the flotation foam used mers is between 0.5 to 30 g per 1000 L of suspension liquid, preferably at 3 to 10 g per 1000 L. According Adding the flotation foamer to the suspension liquid for a few seconds using an agitator kes mixed. Then the plastic mixture fed and the flotation in itself in the flota tion technology known procedures performed.

After the flotation has ended, the foam pro dukt (concentrate) and the chamber product (Rück stand) isolated in a suitable manner and the suspensions liquid added to the process again. Foam and Chamber product can be easily, for. B. by sieving, winning.

After looking at the plastic types mentioned in ABS brought about by the plasma treatment The state of hydrophilization is the fastest to recover regresses - a regression in one for a flota suitable extent has already become apparent with ABS set a few hours - and accordingly after the Storage time with ABS again the greatest hydrophobicity the foam product of the first flota is present tion level from the ABS separated here. yield and content (purity) of the various plastics Fractions are well over 95 weight percent cent. Second fastest among the art mentioned fabrics, albeit much slower than ABS, the modified surface condition is formed on the PC towards hydrophobicity again, which half in a second flotation stage of this plastic is foamed. Then in a third stage a mixture of PPO and SAN with the foam will wear. These two types of plastic would have to be after a modified and with regard to in as far as close fabrics optimized Plasma treatment process or for a reason other procedures are separated. By the way exist - contrary to the inherently hydro ABS, PC, SAN and PPO - certain types of PA, which are inherently hydrophilic and those of the flota tion of a plastic mixture without special preparation act as a pure chamber product.

It was also observed that the pH and the The temperature of the flotation bath affects the Separation effect - at least certain plastics to have. The pH of the flotation bath affects fol to the conditioning of the examined Plastics from: As already mentioned, is ever lost by type of plastic by the plasma treatment induced hydrophilization of the plastic particles different - quickly through storage; ABS will be on fastest hydrophobic again; so it can be a group pe of plastics, from ABS a typical distributor ter is to be distinguished, which is only briefly hydro are philosible. In contrast, there are PPO and SAN due to the plasma treatment, obviously relatively long stably hydrophilizable. Polycarbonates (PC) take in an intermediate position in this regard. It appears now that the pH of the flotation bath is neither on the briefly hydrophilisable plastics ABS on the relatively time-stable hydrophilizable plastics PPO - SAN has not been studied in this regard has an influence; these types of plastic behave agree on the pH of the flotation bath clear, d. H. ABS plastics, i.e. first-class materials called group, can be found both at an alkali as well as with an acidic flotation bath in the Swimming fraction, against which PPO, so the second named in both cases contained substances in the soil fraction are. It is different with the intermediate group. e.g. B. PC; this plastic behaves in an acidic Flotation bath with a pH of about 3 hydro phob, so rises with the foam fraction, whereas he is in an alkaline flotation bath with a pH value of about 10 behaves hydrophilically and drops. In in this context, be to the below Example 3, experiments a and b referenced. Ten in principle, an alkalization of the flotation bath appears the result is similar to outsourcing the plasma hub traded plastic particles at least in the medium long hydrophilizable plastics such. B. PC too Act.

The temperature influence of the flotation bath is too say that warming the different che conditioning of the ABS and PC particles practically eliminated, d. H. in an impermissibly strong, at for example, the flotation bath heated above 33 ° C the different plastic particles (ABS and PC) practically all the same hydrophilic, so that hardly any part float on, but the particle mixture itself almost closed in the soil residue. It So it must be ensured that the flotation bath does not heat up to over 30 ° C. If any heat or energy sources, e.g. B. a constant circulation of Bath liquid for automatic heating of the Should carry out baths, their temperature would have to cooling permissible values are maintained. In this connection also applies to the below referenced example 4, experiments a and b referenced. Open There are energy barriers depending on the material determine bladder attachment and adhesion. Out of it result in a mixture-specific critical bath temperature For example, ABS can be made from an ABSIPC / PPO Mix at a bath temperature of approx. 20 ° C separately against this, but not above 33 ° C is more possible. It cannot be ruled out that the temperature influence described not for all art types of fabric can be observed in the same way. It appears quite conceivable that it is for certain plastic sor a certain, deviate from the room temperature The desired temperature range of the flota tion bath, in which the flotation separation particular that runs effectively. Such an influence of temperature, in particular the presence of a limit temperature or a possible optimum temperature of the flotation Baths would have to be examined or searched for on a case-by-case basis.

The purity of the plastics obtained - can through suitable, mostly analytical methods check. For different colored plastics, the Check the purity optically chatting. With plastics of the same color, the over purity test according to the usual chemical Procedures are carried out, for example by selective soldering sen.

To explain the present invention Examples that have been carried out in the following riert. The two comparative tests according to Example 1 show gene that neither the untreated flotation nor a Float with mere plasma pretreatment of art a separation of the mixture into its material components. Example 2 shows the substance-specific diversification of the conditioning both by plasma pretreatment and subsequently eating storage. The two comparison attempts after Example 3 show the effect of an acid and one  alkaline flotation bath on the medium long Plasma treatment hydropilatable plastic PC and finally, the two attempts by Example 4 the influence of the bath temperature.

example 1

A mixture of 10 g ABS (to facilitate the Control colored black), PC (transparent) and PPO (colored gray) in the form of regrind the grain size class 4.0-6.3 mm sieve size is in a han standard plasma chamber at a base pressure of 10 Pascals a microwave excited (13.56 MHz) Oxygen plasma for a period of 10 seconds exposed. After the plasma treatment it will Verify the plastic mixture in an airtight sample bag packs and stored for a period of 8 days. After the storage period, the plastic mixture is in given a pneumatic flotation cell. The cell is with 9 L tap water (pH about 8, temperature about 20 ° C) filled by the flotation foamer Flotan ol® C7 in a concentration of 5.5 g per 1000 L. Water is added. Then the flotation takes place according to known methods. In the foam product 9.78 g of ABS are applied in the chamber product remain 20.22 g mixture of PPO, PC and ABS, wor the latter contains 0.22 g. The foam product consists of 100 percent by weight ABS.

Attempt a

Analogous to example 1, but without plasma treatment of the plastic mixture. There is no separation instead of; all mixture components accumulate bubbles are applied in the foam product

Attempt b

Analogous to example 1, but flotation directly after the Plasma treatment of the plastic mixture. It takes place also no separation takes place; none of the mixed comm components accumulate bubbles and therefore all remain Components in the chamber product

Example 2

A mixture of 10 g ABS (this time from control establish brown colored), SAN (transparent) and PPO (gray) in the form of regrind in the grain size class 4.0-6.3 mm sieve width becomes analogous to example 1 Subject to plasma treatment, but this time for egg stored for a period of 45 days. The subsequent one Flotation is also analogous to example 1. In Foam product is applied 9.68 g of ABS, in Chamber product remains 20.32 g of SAN, PPO and ABS, which contains 0.32 g of the latter. The Foam product consists of 100 percent by weight SECTION.

Example 3 (on the influence of the pH value)

Experiment a: A mixture of 10 g ABS (black), PC (transparent) and PPO (gray) in the form of regrind in the grain size class 2.5 to 4.0 mm sieve is subjected to a plasma treatment analogously to Example 1 and then 20 Stored for days. The plastic mixture is then placed in a pneumatic flotation cell. This is filled with 9 liters of water at a temperature of around 20 ° C, to which a Flotanol® C7 floatation foamer is added in a concentration of 5.5 g per 1000 L of water. A pH of 3 is adjusted by adding dilute sulfuric acid (H₂SO₄). It is then floated in a known manner. 10.00 g ABS, 9.85 g PC and 0.21 g PPO are applied in the foam product, whereas 0.15 g PC and 9.79 g PPO remain in the chamber product.

The purity of the chamber product PPO is 98.5 Percent by weight.

Experiment b: Analogous to experiment a, but setting the pH value by adding dilute sodium hy hydroxide solution (NaOH) to about 10. In the foam product 9.98 g ABS, 0.45 g PC and 0.04 g PPO brings; 0.02 g ABS remains in the chamber product, 9.55 g PC and 9.96 g PPO. The purity of the foam pro ductile ABS is 96 percent by weight

Example 4 (on the influence of temperature)

Experiment a: A mixture of 20 g ABS, PC and PPO in the form of regrind in the grain size class 4.0 to 6.3 mm sieve width is analogous to Example 1 of a Plas undergo treatment and then for 20 days stored. The plastic mixture is then in given a pneumatic flotation cell. This is filled with 9 liters of tap water (pH about 8), which a flotation foamer Flotanol® C7 in a con concentration of 5.5 g per 1000 L of water is added. The The temperature of the flotation bath is 19 ° C. On finally float in a known manner. In the foam 20.00 g ABS and 0.50 g PC are applied, whereas in the chamber product 19.50 g PC and 20.00 g PPO remain. The purity of the foam product ABS is 97.5 percent by weight.

Experiment b: Analogous to experiment a, but temperature the bath liquid about 41 ° C. Who in the foam product the 0.16 g ABS and 0.92 g PC applied; in the chamber product remain 19.84 g ABS, 19.08 g PC and 20.00 g PPO.

Claims (24)

1. A process for the pure separation of plastic particles from a particle mixture of different plastics by flotation, in which the plastic particles are treated superficially with a view to a variety-dependent change in their wetting behavior, such that the different types can be floated individually from the particle mixture, characterized in that the superficial treatment of the plastic particles in the Hin view of a species-dependent change in their Benetzungsver holding before the floating and outside the Flotationseinrich processing is carried out by plasma treatment of the particulate mixture and then stored on dry-physical manner.
2. The method according to claim 1, characterized, that the plastic mixture before the plasma treatment to a par Particle size with a diameter of less than 20 mm is noted.
3. The method according to claim 2, characterized, that the crushing of the plastic mixture before the plasma act on a particle size with a diameter of about 2 up to 12 mm.  
4. The method according to claim 1, characterized, that the plasma treatment of the particle mixture in batches loose bulk.
5. The method according to claim 1, characterized, that the plasma treatment of the particle mixture is continuous he follows.
6. The method according to claim 5, characterized, that the continuous plasma treatment of the particle mixture in the case of occasionally adjacent particles.
7. The method according to claim 1, characterized, that the plasma treatment of the particle mixture over time duration of 1 to 120 seconds.
8. The method according to claim 7, characterized, that the plasma treatment of the particle mixture at smaller loading handling systems and / or lower bulk layer thicknesses via egg ne duration of 5 to 10 seconds.
9. The method according to claim 7, characterized, that the plasma treatment of the particle mixture with larger loading handling plants and / or larger bulk layer thicknesses over a Duration of 60 to 120 seconds.
10. The method according to claim 1, characterized, that the plasma treatment of the particle mixture in an abge closed treatment chamber in the presence of a microwave  excited process gas at a pressure of less than 200 Pa follows.
11. The method according to claim 10, characterized, that as a process gas in the plasma treatment of the particle mixture microwave-excited oxygen is used.
12. The method according to claim 10, characterized, that with smaller treatment plants and / or less bulk layer thicknesses a pressure of about 10 Pascal is used.
13. The method according to claim 10, characterized, that with larger treatment plants and / or stronger Schüttla pressure of at least about 30 Pascals is used.
14. The method according to claim 1, characterized, that the plasma treatment of the particle mixture in free atmosphere sphere in the presence of air with continuous promotion of the Particle mixture to be treated through a treatment section through it.
15. The method according to claim 14, characterized, that the atmospheric oxygen and / or the atmospheric nitrogen within the Treatment route is excited to a plasma.
16. The method according to claim 15, characterized, that the plasma excitation of atmospheric oxygen and / or air nitrogen by means of a so-called direct barrier discharge.
17. The method according to claim 1, characterized,  that the plasma-treated particle mixture before the flotation stored for at least about five hours.
18. The method according to claim 17, characterized, that the previous storage of the plasma-treated particle mixture is spread over several days.
19. The method according to claim 1, characterized, that the storage of the plasma-treated particle mixture in free Atmosphere in a loose bed.  
20. The method according to claim 1, characterized, that to separate the mixture of the conditioned plastic par the flotation bath is acidified by flotation, whereby art that can only be hydrophilized briefly by plasma treatment substances and medium-long hydrophilisable by plasma treatment Float plastics and time-stable through plasma treatment plastics that can be conditioned in a hydrophilic manner sink.
21. The method according to claim 20, characterized, that the acidification of the flotation bath to pH values of less than 4 he follows.
22. The method according to claim 1, characterized, that to separate the mixture of the conditioned plastic par the flotation bath is alkalized by flotation, whereby art that can only be hydrophilized briefly by plasma treatment fabrics on float and time-stable due to plasma treatment hydro phil can be conditioned plastics and by plasma treatment plastics that can be hydrophilized over a medium period of time.
23. The method according to claim 22, characterized, that the alkalization of the flotation bath to pH values above 10 takes place.
24. The method according to claim 20 or 22, characterized, that the flotation bath to a mixture-specific optimal tem temperature set and kept constant at this temperature becomes.
DE1995119865 1994-08-05 1995-05-31 Process for sorting plastics from a mixture of particles of different plastics Expired - Fee Related DE19519865C2 (en)

Priority Applications (2)

Application Number Priority Date Filing Date Title
DE4427718 1994-08-05
DE1995119865 DE19519865C2 (en) 1994-08-05 1995-05-31 Process for sorting plastics from a mixture of particles of different plastics

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DE1995119865 DE19519865C2 (en) 1994-08-05 1995-05-31 Process for sorting plastics from a mixture of particles of different plastics
CH02247/95A CH689380A5 (en) 1994-08-05 1995-08-03 A method for sorting of plastics from a particle mixture of different plastics.
JP21830695A JP2797072B2 (en) 1995-05-31 1995-08-04 Method for selecting synthetic resin from a mixture of particles of various synthetic resins
US08/512,525 US5566832A (en) 1994-08-05 1995-08-07 Method for sorting plastics from a particle mixture composed of different plastics

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Cited By (1)

* Cited by examiner, † Cited by third party
Publication number Priority date Publication date Assignee Title
DE19741323A1 (en) * 1997-09-19 1999-03-25 Daimler Benz Ag Differentiation and separation of mixed, coarse plastic granules

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Publication number Priority date Publication date Assignee Title
CA2246422A1 (en) * 1997-08-29 1999-02-28 The Pilot Ink Co., Ltd. Direct liquid supply writing implement
DE19758575C2 (en) * 1997-09-19 2001-08-30 Daimler Chrysler Ag Process for changing the surface properties of a particle mixture and device for carrying out the process

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JPS5032270A (en) * 1973-07-21 1975-03-28
GB1473274A (en) * 1974-03-14 1977-05-11 Mitsui Mining & Smelting Co Method for separating a mixture of plastics
US4167477A (en) * 1978-01-17 1979-09-11 The United States Of America As Represented By The Secretary Of The Interior Separation of plastics by flotation
US5120769A (en) * 1990-04-30 1992-06-09 Basf Aktiengesellschaft Process for the preparation of thermoplastic syntactic foam and thermoplastic powder compositions suitable therefor
CA2073951C (en) * 1991-08-02 1996-12-03 Jiann-Yang Hwang Separation of normally hydrophobic plastic materials by froth flotation
US5248041A (en) * 1991-09-14 1993-09-28 Hoechst Aktiengesellschaft Process for the separation of plastics by flotation

Cited By (2)

* Cited by examiner, † Cited by third party
Publication number Priority date Publication date Assignee Title
DE19741323A1 (en) * 1997-09-19 1999-03-25 Daimler Benz Ag Differentiation and separation of mixed, coarse plastic granules
DE19741323C2 (en) * 1997-09-19 2000-03-09 Daimler Chrysler Ag Process for sorting plastic particles from a particle mixture of different plastics by flotation and device for carrying out the process

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