WO1994014542A1

WO1994014542A1 - Process and device for the mechanical separation of metal-containing plastic mixtures and compounds

Info

Publication number: WO1994014542A1
Application number: PCT/DE1993/000793
Authority: WO
Inventors: Detlef Schulz
Original assignee: Wemex Ingenieurbüro Gesellschaft Für Mechanische Aufbereitungstechnik Mbh
Priority date: 1992-12-23
Filing date: 1993-08-26
Publication date: 1994-07-07
Also published as: AU6808494A; DE4244449A1

Abstract

The invention relates to a technology and a device for the space-saving, economical and non-polluting separation of metal-containing plastic mixtures and compounds, e.g. electronic and small instrument waste. The prior art thermal, chemical and mechanical processes are inadequately designed for the recovery of directly usable metal and plastic fractions. According to the invention, besides the extensive separation of plastic and metal, it is possible to recover various re-usable metal and plastic fractions which, in subsequent processing steps, provide an important source of products, especially non-ferrous metal components which can be processed into powder-metallurgical products without electrolysis. The necessarily pre-finely divided material compounds or mixtures are largely freed from ferrous components and taken to either a hammer mill (1) or a cutting granulator (2). After air-separation (3), the light fraction is sorted into at least 3 grain size ranges. The heavy fraction is freed from the residual ferrous components and also sorted. A coarse fraction is taken via a sorting machine (19) in which at least one non-ferrous metal concentrate is separated off. The fine fraction is taken to a dry-mechanical density separator (10, 11) and decomposed into at least 3 basic fractions, whereby copper strands are added to the agglomeration. The process is performed in a special, compact, container-like, transportable plant.

Description

description

Method and device for the mechanical separation of metal-containing plastic mixtures and composites

The invention relates to a mechanical method for material separation of metal-containing plastic mixtures and composites according to the preamble of claim 1 and to a compact device for performing such a method according to the preamble of claim 7.

The recycling of materials from small device scrap and other metal-containing material mixtures and compounds requires a sorting according to recyclable groups of substances. The variety of materials found in metal-containing plastic mixtures and composites, such as printed circuit boards, electronic devices, small electrical devices, cables, vehicle dashboards, etc., presents extraordinary difficulties in recovering individual components of recyclable materials.

Up to now, material recovery from electronic scrap has mainly been carried out by combustion, pyrolysis or other thermal processes for the decomposition of the plastics with subsequent metallurgical treatment and / or electrolysis. Significant amounts of primary energy are required if a high proportion of non-combustible material has to be heated without effective mechanical pretreatment and larger amounts of unusable waste are produced. Cf. also DE-PSen 2130049, 2054203 and DE-OSen 2142760, 2739963 and 2626589. The elements Ni and Cu act as a catalyst in the formation of toxic dioxins and furans. This effect is reinforced by the presence of halogenated flame retardants and PVC.

Another disadvantage is that the pollutants incorporated in many plastics, e.g. Heavy metal stabilizers are released.

Various chemical processes are known which involve dissolving the metals with inorganic or organic acids and lyes, salt separation and reducing the metals, and which can be used for material recovery from electronic scrap (cf. DE-OSen 1592499, 3640028 and 1483161 ).

The expenditure on equipment for reducing the environmental impact and for producing the necessary product purity is extremely high in thermal and chemical processes and limits their profitability to electronic scrap containing more precious metals.

Because of the manifold problems in the process control of thermal and chemical recycling processes in the processing of untreated equipment scrap The inhomogeneity and variety of materials are increasingly reduced by prior mechanical processing, for example by comminution and separation of substances, so that extensive pre-sorting into ferritic iron alloys, non-ferrous metals. Glass and plastic are made, which are then further processed using different thermal and / or chemical processes. This ensures that no significant contaminated plastic residues are contained in the metal fractions after the separation. In recent times, harmful components such as PCB capacitors, mercury switches, NC batteries and, in case of doubt, unknown components have been manually removed and materials have been sorted according to material groups before shredding is started.

Various mechanical methods for processing metal-containing plastic mixtures and composites are known.

Although the disadvantages of the thermal and chemical processes outlined would give preference to mechanical solutions for economic and ecological reasons, their current technical status cannot yet be satisfied.

Different material properties of the components used in devices quickly lead to malfunctions. Cables and lines can wrap around machine elements, copper also tends to friction welding, which can lead to considerable problems. Ceramic parts that are used as a carrier material for resistors and circuits, ferrite cores of coils as well as iron and steel and stainless steel parts lead to heavy wear during cutting comminution processes. The toughness of the reinforced laminates and ductile metals complicate impact and impact crushing processes. In addition, the material often heats up during comminution, which can soften the thermoplastics and thus lead to smearing. To improve the crushability of this material, e.g. Before it is ground with liquid nitrogen, it becomes brittle, which is associated with high energy expenditure and can lead to condensation problems.

For this reason, attempts are increasingly being made to counter these problems by means of multi-stage comminution with downstream separation stages for pieces of material that have already been sufficiently exposed.

Methods are already known for separating mixed material comminuted with hammer mills or other impact and tear crushers by means of air classifying, sieving, eddy current non-separating and electrostatic separation (e.g. DE-OS 3923910.1 and EPA no .: 90810655.2). In the case of inhomogeneous and strongly fluctuating material qualities, a satisfactory process control is often only possible in different machine chains specially designed for the individual material components.

However, the mechanical processes known from the prior art are designed in such a way that they lead to metal fractions which in any case have to be subjected to an electrolytic and thermal aftertreatment, even in those cases in which the starting materials contain particles made of chemically pure metals or alloys that would be usable without melting and electrolysis.

The invention has for its object to provide a dry-mechanical process and plant technology solution, which in addition to the metal-plastic separation, the separation of non-ferrous metal fractions that can be processed directly to sinter powder with a defined composition.

Because of the wide variety of materials and mixed compounds present in the device scrap, the focus of the proposed technology should not be on separating raw materials that are as pure as possible, but on mixtures of materials whose further processing requires little effort to achieve secondary raw materials with a high added value.

However, the separation of high-purity raw material fractions should not be ruled out (e.g. when processing cable scrap and pre-cleaned mixtures). In particular when processing low-grade electronic scrap, the process is intended to separate copper components from the other diverse alloys from which the components are made, in order to reduce the proportion of non-ferrous metals to be further processed electrolytically.

The aim is to create a machine arrangement that is as simple as possible, that is suitable for processing a wide range of materials, and that fulfills the specified function with little disruption. The most important parameters should be freely selectable. In addition, a compact embodiment is to be chosen in which the necessary mechanical process stages and the air supply devices are combined in a portable machine.

This object is achieved in the generic method according to the invention by the characterizing features of claim 1 and in the generic device according to the invention by the characterizing features of claim 7.

The processing of equipment scrap according to the method according to the invention requires a coarse shredding by known cutting or tearing scrap shredders, which ensure the most homogeneous grain size and length of about 25 mm, with a sufficiently good digestion to obtain a qualitatively adequate iron scrap fraction.

The method according to the invention offers advantages through the use of the "Klauben" method step for non-ferrous metal piece deposition compared to the eddy current separating method which is otherwise usually used for non-ferrous metal deposition. Using a special detection sensor system, only the large clumps of metal can be separated, while small metal structures and composites that are to be further shredded cannot be detected. Stainless steel and lead components can also be separated. By using different special sensors, metal separation, color sorting, glass-ceramic sorting and possibly different NE- Realize metal sorting in one machine without the need for major retrofitting.

The metal-plastic separation by classifying and multi-stage density separation instead of the known electrostatic separation processes by means of L-C, offers the advantage that electrically conductive plastics, plastic particles wetted with conductive liquids or surface-metalized plastic particles do not get into the metal fraction and the influence of grain size on the separation quality at the the flow method used is larger due to the principle. Classifying the classifier light fraction offers the advantage that a low-dust film / flake fraction can be obtained from device scrap, which e.g. can be used in the furniture industry. Metal debris can subsequently be better separated from the screened dust.

The advantages of the device according to the invention are that it is possible to carry out metal-plastic separation, film-fiber separation, dust separation, iron recovery and aluminum-copper separation from complex material mixtures such as mixed cables, populated printed circuit boards, metal-containing device housing parts and shredder fractions with a compact machine has a self-contained functionality and its area of application is expandable. While on the one hand high purities can be achieved in the metal fraction, on the other hand it is not possible due to the known devices for density separation used to cleanly separate stranded hair, aluminum foil pieces and copper-coated plastic parts (printed circuit board parts) from the light plastic fraction. The tendency of copper strands to get caught and to form lumps on the air stoves used for density separation is used to largely separate these copper fractions from the other diverse non-ice metal alloys (in the density range of the copper), which are generally not in wire form. Two air stoves arranged in a row also offer advantages when processing mixed cables by largely separating copper and aluminum. In a subsequent process step, the plastic fraction is selectively ground (see DE-OS 4213274.6), so that the thermosets and ceramics are ground, most (impact-resistant) thermoplastics are largely preserved as pieces, and the ductile metal fractions are predominantly pure copper, solder metal and aluminum be balled, after which they can be separated well with classification and density separation processes. A further advantage for the processing of the non-ferrous alloy mixtures, which are then largely freed from copper wires, is that this results in an increase in the concentration of the noble metal components in this fraction. The compact design, designed as a transportable container, allows mobile operation if required. This shows transpoitlogistic advantages that stationary processing plants do not offer.

In view of the legal requirements for the avoidance of residues and waste materials, the method according to the invention represents an environmentally friendly and inexpensive possibility of enriching valuable materials from metal-containing plastic waste and production residues. It forms a link between waste disposal and recycling of valuable materials by using dry-mechanical waste from metal-containing plastic and light scrap Recyclable secondary raw material concentrates can be produced at room temperature without the addition of solid or liquid auxiliaries, which, if necessary, can be further mechanically enriched and refined.

The method and the device according to the invention are explained in more detail below using an exemplary embodiment. In the accompanying drawings: Fig.l shows the process flow diagram Fig.2 the inventive device

The free-flowing metal-containing plastic material arrives in a suitable conveyor in the device according to the invention after a magnetic separator, with which ferrous iron alloys can be removed. Depending on the material, you can choose between two different shredders, both of which are connected to the following separation devices. In a hammer mill (1), the composite material is broken, preferably at joints, by selective comminution, brittle components are greatly comminuted and larger pieces of ductile metal are only rounded off. It is relatively unaffected by larger metal and ceramic particles. The use of a vertical hammer mill offers advantages when processing materials with a high content of bright metals. In the cutting granulator (2), cables and pre-cleaned, metal lump-free material fractions are preferably comminuted to a finer particle size. A gravity classifier (3) after comminution ensures that the lumpy material is separated from light fiber, film and dust components, which are separated from the carrier medium by air in a dust separator (4) and can then be separated and used by suitable sieve classifying devices (5). Suitable oscillating movements of the sieve device (5) can cause fibers to agglomerate, which can then be separated by a further sieve (6). A classifier heavy fraction is conveyed upwards again and freed from ferritic residual fractions with an iron separator (7). Classification is then carried out using a sieve (8). The coarse fraction is passed through an electronically controlled chewing device (9), where at least one non-ferrous metal concentrate is separated. The minimum piece size of the metal fraction to be separated can be set via the sensor sensitivity. This ensures that thin copper wires and other fine metal structures that are usually still attached large pieces of plastic stick, cannot be detected. The fine fraction reaches devices for dry-mechanical density separation and is broken down into at least 3 basic fractions. In the device according to the invention, this is realized with two air stoves (10, 11) connected in series, which operate according to the inflow method. Vibrating movements of the inclined, air-flowed, textured surfaces of the air sources cause agglomeration phenomena of fine copper wires and strands. The copper strands agglomerated into mats are regularly drawn off via a clearing device, while the heavy, lumpy metal particles leave the device via the heavy material discharge. To reduce the fresh air consumption of the machine, multiple use of pre-filtered exhaust air takes place inside the machine. Only a part of the air volume from the open circuit mills (1 and 2), wind sifter (3), compact dust extractor (4), blower (12) and return (13) via a distributor valve (14) into an exhaust duct (16) while the remaining air is returned to the air classifier (3) (partial air recirculation mode). Likewise, the amount of air required for the air sources (10 and 11) is dedusted using a compact filter (16) and only an adjustable amount of leakage air is transferred to the exhaust duct (16) via a distributor valve (15). If necessary, another air-consuming machine or an absolute filter can be connected to this exhaust duct. The soundproofed containe-shaped system is brought to such a working height for operation that containers or conveyors can be placed underneath to hold the separated bulk goods.

Claims

1. Process for the mechanical separation of metal-containing plastic mixtures and composites by crushing, magnetic separation, sifting, classifying and non-ferrous metal-plastic separation, characterized in that the non-ferrous metal-plastic separation by classifying and two density separation stages connected directly in series and the non-ferrous metal / recyclable material is separated by picking.

2. The method according to claim 1, characterized in that the separated after crushing the input material in the air classifier light fraction in at least three

Grain size ranges are classified and that in the fractions in the grain size range 0.3-3 mm fibers are agglomerated by oscillating movements of the sieve classifying device and then discharged.

3. The method according to claim 1, characterized in that after the classification of a largely iron and dust-free coarse fraction, the non-ferrous metal concentrate and other valuable materials, e.g. Plastic particles of the same color, preferably in the grain size range of 4-25mm, are sorted out by chewing so that only a residual metal content of almost exclusively fine metal structures remains in the non-metal fraction.

4. The method according to claim 1, characterized in that after the classification of a largely iron and dust-free fine fraction by means of the density separation stages, the material is separated so that the metal fractions are largely free of plastic and fine copper wires, aluminum foil and metal-coated Ku___tsto__particles remain in the plastic fraction, whereby the copper wires are agglomerated and then discharged.

5. The method according to claim 1 to 4, characterized in that multiple use of pre-filtered exhaust air takes place within the individual process stages air separation and density separation by a partial amount of air from the open circuits in circulating air operation.

6. The method according to claim 1 and 2, characterized in that the screened dust in the grain size range <0.3 mm after-treated by wind sifting and is thus freed from metal parts.

7. Device for performing the method according to claim 1 to 5, characterized in that within a container-lined with sound-absorbing material container-like portable container at least one hammer mill (1) and a cutting mill (2) together with a wind sifter (3) and then chained with classifying devices. Scattering device and density separators for further treatment of the air classifier fractions are connected.

8 .. Device according to claim 7, characterized in that at least one dust separator (4) with a downstream screening device (5) for processing the classifier light fraction is present.

9. The device according to claim 7, characterized in that with a heavy material outlet of the air classifier (3) at least one iron separator (7), a classifying device (8), one

Klaubevvorrichtung (9) and two series-connected density separation devices (10, 11) are chained.

10. The device according to claim 7 and '9, characterized in that the chucking device (9) is arranged after the coarse material discharge of the classifying device (8). 11. The device according to claim 7 and 9, characterized in that the two series-connected density separation devices (10,

11) are arranged after the fine material discharge of the classifying device (8).

12. The apparatus of claim 7, 9 and 11, characterized in that the density separation devices (10, 11) are designed as air stoves, each separating only two fractions and which have a clearing device for discharging the agglomerated copper wires.

13. The apparatus of claim 7 and 8, characterized in that for regulating the partial air flow between the compact dust extractor (4) and air classifier (3) with the exhaust duct (17) connected distributor valve (14) is arranged 14. Device according to claim 7 and 11, characterized characterized in that a distributor valve (15) connected to the exhaust duct (17) is arranged to regulate the partial air flow between the air sources (10 and 11) and the filter (16).

Two sheets of drawings