DE9116529U1 - Recycling plant for plastic waste contained in household and/or hospital waste - Google Patents

Description

Recycling facilities for plastic waste contained in household waste and/or hospital hazardous waste

The invention relates to a recycling plant for plastic waste contained in household waste and/or in hazardous hospital waste.

With the increasing amount of waste from different sources such as household waste, commercial waste, industrial waste, or hazardous waste such as hospital waste, chemical waste and the like, as well as with the simultaneous increase in raw material prices, the interest of the public and of waste-producing companies in the economic recycling of waste materials is growing. This is all the more so because, in addition to the increase in waste quantities, the problems arising from its disposal, primarily environmental problems, are constantly increasing and thus causing higher costs.

For example, DE-PS 39 34 258 Cl describes a recycling process and system for oil-contaminated equipment. In this process, the equipment is collected and certain materials are sorted and/or cleaned for further use. The waste materials are roughly pre-sorted according to material, certain of the pre-sorted parts are shredded, the shredded parts are separated according to material, parts of them are washed and the washed parts are separated according to different materials. A portion of this is reused, while another portion is disposed of, incinerated or landfilled depending on the type and degree of contamination and the materials.

The disadvantage is that the system required for this is extremely large and therefore requires high investment costs, which can only be recouped if the system is fully utilized. Furthermore, even with this complex process, the proportion of reusable material depends on the type and condition of the material and is often unsatisfactory. The conditions required for the economic operation of such systems, in particular a collection system for a sufficiently large and consistent throughput, can only be achieved in rare cases, which is why the proposed recycling system has not yet been able to prevail.

DE - PS 32 48 493 C2 describes a process for recovering valuable materials from mixed waste from the construction industry and a plant for carrying out the process. This process is also complex and requires high investment costs for a corresponding plant. The mixed waste delivered is screened in front of an intermediate bunker and the screening is passed on, then wood suitable for further processing is separated by hand from the intermediate bunkered screen overflow before it is shredded, the shredded material is separated into a fine and coarse fraction after iron separation, the screening of this screening together with the screening that also went through iron separation is separated in a two-stage screening into a fine, medium and coarse fraction, the coarse fraction is separated by air sifting into a light and a heavy fraction, non-ferrous metals are removed from the light fraction while the combustible fraction remains and non-ferrous metals and combustible material are separated by hand from the heavy fractions while the stone fractions remain, and the fine and medium fractions of the two-stage screening are sifted into a sand-like fraction, a combustible fraction and a stone fraction.

This well-known process and the corresponding plant are also extremely complex, they also require a high level of investment and operating costs, which is why economic operation is only possible with permanent full capacity. Since it involves mixed waste from the construction industry, primarily demolition material and the like, high transport costs are also incurred, which is why this well-known process and the corresponding plant have not yet achieved any significance.

The situation is similar when reusing recyclable plastics, especially from household waste and/or hospital hazardous waste. The recycling industry is only interested in plastic material that has been sorted by type and which must also be processed in such a careful manner that no significant amounts of foreign matter or dirt adhere to it. In order to achieve this, known methods of floating and sinking processing have already been proposed for the sorting and processing of pre-shredded plastic waste. Such a floating and sinking vessel for separating and removing sinking and suspended particles is known from DE-PS 28 03 164. In column 2, second paragraph, it is stated, among other things, that known floating and sinking vessels are not sufficiently suitable for separating, for example, shredded plastic parts. Such plastic parts are sometimes provided with adhering paper parts, which detach in the vessel liquid and, depending on the density, then float in the liquid, float on its surface or sink to the bottom of the vessel.

In order to make the floating-sinking process suitable for the pure separation of plastic particles, the mixture must be set in motion with a high energy input in order to separate plastic parts and adhering dirt and/or paper particles before separation. These or similar processing processes and the mechanical equipment required for them also cause comparatively high costs, so that the economic incentive for such recycling processes and devices is very limited.

Attempts have therefore already been made to make a process for sorting plastic hollow bodies from garbage, especially from household garbage, more economical by moving the unsorted plastic hollow bodies on a conveyor line past or under an optical detection device that is connected to a storage and marking device for identifying the various plastic hollow bodies, and by arranging branches, switches or the like downstream on the conveyor line, which, controlled depending on the identified plastic hollow bodies, release feeds to individual intermediate collection containers for collecting plastic hollow bodies of the same type. For this purpose, the plastic hollow bodies should advantageously be marked with an optically detectable code (DE - PS 35 20 486).

But this method also remains questionable because, on the one hand, only hollow plastic objects are detected, and on the other hand, these are sometimes passed past a detection station in such a way that the identification device of the optical detection device is not able to assign them to the corresponding learned models and therefore does not recognize them.

Overall, it can be stated that the existing proposals for recycling processes and recycling plants for different types of waste and types of origin do not meet either the economic or practical requirements for sorting out waste and producing usable products using economical means and a high level of collection, which on the one hand are worth the effort required for this and on the other hand can be used sensibly in a suitable place.

Based on the aforementioned prior art, the invention is based on the object of specifying a recycling plant for plastic waste contained in household waste and/or hospital special waste, with which it is possible in an economically viable manner to manufacture products from the plastic waste obtained that are preferably suitable for problem-free disposal and can also be used in practice when setting up landfills.

The solution to the problem is achieved with a recycling plant for plastic waste contained in household waste and/or in hospital special waste with the invention in that a plastic fraction contained in the household waste and/or hospital special waste is sorted out in a delivery station and a mixed plastic raw material consisting of different types of plastic and containing parts of adhering contaminants is obtained and this is further processed unsorted to manufacture products.

The measure proposed by the invention, of mixing together parts of the most varied plastics with adhering impurities to form a mixed plastic raw material and further processing this mixture unsorted to manufacture products, obviously contradicts the previously established opinion of the experts that only plastic parts sorted by type can be recycled. It is all the more surprising that the invention proposes a recycling plant with the help of which the further processing of an unsorted mixed plastic raw material is made possible. But it is precisely through this proposal according to the invention, which contradicts widespread experience among the experts, that the previously existing economic barrier to recycling plastic parts is surprisingly broken down and a particularly economically advantageous solution is shown for processing such mixed raw material into usable end products.

One embodiment of the invention provides that a plastic fraction sorted out from hospital waste is first pre-shredded and disinfected in a shredding and disinfection station and thereby processed into waste similar to household waste, but in sterile form, and then mixed into the mixed plastic raw material obtained from household waste.

Because the plastic content in hospital waste is particularly high, another proposal is to sort out the plastic fraction from the hospital waste using mechanical means. This has the advantage that human workers do not come into contact with the hospital waste,

Another design provides for the plastic fraction from the household waste to be read out manually in a reading station.

Such a manual sorting process for waste is well known and leads to a comparatively productive sorting result at economically justifiable costs.

One embodiment further provides that pre-shredded mixed plastic material obtained from household waste and/or hospital hazardous waste is initially stored temporarily and delivered from one or more intermediate storage facilities to a central processing station and is initially shredded in a fine shredding stage, batches of shredded material that arise are fed into a silo and mixed and stored there, and then an intermediate extrusion product, preferably in the form of a strand, is produced using an extruder and this is cooled in a cooling calender during the further pass, heated in a diathermy station that preferably generates a high-frequency field, then the extrusion strand is shredded into pellets, the pellets obtained are temporarily stored and usable products are made from the pellets in a final processing process.

It is advantageously provided that the pre-shredded plastic chips are shredded in the fine shredding stage to a particle size of on average less than 10 mm, preferably 4 to 6 mm.

One embodiment provides that the final processing method is an injection molding process. This is particularly advantageous because it allows the intended end products to be molded in a specified and economical manner.

However, it is also possible that, according to an alternative proposal, the final processing method is an agglomeration and shaping process using a preferably hydraulic binding agent such as a cement/water mixture with or without blast furnace slag or a mortar that is insoluble in water after hardening. Here too, shaped bricks can be produced from the pellets using economical, economic means and using known plant elements.

According to a further proposal, a process step that can be integrated into the process sequence can be carried out in such a way that after the first and/or second crushing stage, an intermediate sieving is carried out, in which parts of fine matter, in particular adhering impurities or liquid and/or foreign matter released during crushing are sieved out of the mixed plastic raw material.

And finally, one embodiment provides that the method is used to manufacture in particular earth-bound, i.e. suitable for use in contact with the ground, usable products such as landfill aeration stones, cable cover plates, drainage pipes and similar simple building blocks or elements.

A recycling plant for producing products from plastic waste, in particular for carrying out the method described above, provides plant components corresponding to the features a) to c) of the main claim. Further advantageous embodiments are provided in accordance with the features of claims 2 and 3.

Further details, features and advantages of the invention emerge from the following explanation of an embodiment shown schematically in Figures 1 and 2. They show:

Figure 1: A purely schematic representation of the family tree of the described procedure.

Figure 2: A perspective view of a system according to the invention, also shown purely schematically.

In Figure 1, a motorized work train consisting of a motor vehicle and two trailers is shown at the top left, which has a device 1 for sorting out a plastic fraction from hospital hazardous waste in the motor vehicle, behind it in the first trailer a coarse shredder 2 and downstream of this a plastic chip disinfection device 13. These units are followed by a transportable coarse material storage unit for the sorted and pre-shredded plastic material in the second trailer. In the level below, a household waste processing station is shown, comprising a feed bunker 14 and a subsequent hand-picking belt 4 for manually sorting out plastic parts. These are then sorted into the containers shown to the side of the belt 4, whereby other types of waste such as glass etc. can also be sorted out and used for another purpose. The plastic parts sorted out of the garbage by the hand-picking belt 4 are then fed into a coarse shredding device with the shredder 5 and the chips produced are loaded into the coarse material storage unit 3b, which is also transportable. In these transportable coarse material storage units 3a and 3b, household garbage and/or

Pre-shredded plastic mixed raw material obtained from hospital hazardous waste is initially intermediately stored and then delivered from one or more intermediate storage facilities to a central processing station and then initially fed into a storage silo 16. The material is then mixed and homogenized again and delivered in such a quantity per unit of time that the subsequent processing can take place in a continuous flow through the individual work stages. From this storage silo 16 (Figure 2) for plastic mixed raw material, it is fed into a fine-grinding device, preferably having a grinding device 6, with a connected fine-material silo 15 and the finely shredded material is mixed again and stored in this silo. From the intermediate silo 15, the finely shredded mixed raw material is fed into an extrusion device, preferably having a twin-screw extruder, and processed into an extrusion strand 20.

Because the plastic waste contains 15 to 20% foreign matter depending on how it is extracted and can also contain abrasive materials such as sand, the screw extruder 7, which is known per se, is equipped with special, highly wear-resistant and particularly strong internal parts and tools. Because the plastic is converted into a partially viscous state under heat and pressure within the extruder and thus produces a kind of lubricating film, an extruder equipped with highly wear-resistant and particularly strong internal parts is able to work without problems with a long service life and corresponding availability. This is also a surprising, advantageous result of the invention for the professional world.

As the system diagram according to Figures 1 and 2 shows, the extrusion strand 20, after leaving the extruder head, is passed through a cooling section with a cooling calender 8 and, immediately thereafter, through a diathermy system 9 equipped with means for generating a high-frequency field, after which the extrusion strand 20 is chopped into pellets in a granulator-cutting machine 10. These pellets are temporarily stored in a storage silo 17 and then fed to a final station with an end product manufacturing device 18 for the production of end products. The end product manufacturing device 18 is then connected to a finished product storage area 19 in some cases. As shown in Figures 1 and 2, the end product manufacturing device 18 can advantageously have an injection molding machine 11 with means for molding the end products. 20 designates receiving containers for end products.

The end product manufacturing facility 18 can also comprise a machine system known per se for producing shaped bricks using hydraulic binding agents that bind the pellets, such as Portland cement, HO slag, water-insoluble mortar, etc.

Products such as usable earth-bound landfill cover stones, cable cover plates, drainage pipes, molded stones and the like are particularly suitable as end products made from mixed plastic raw material or the pellets produced from it. These are characterized in that they are manufactured according to the described process using pellets from unsorted mixed plastic raw material. As a result of the previous processing stages, in particular extrusion stage 7 and the molding, preferably in the injection molding process, the mass of the raw plastic material is mixed, welded, glued and thereby homogenized with the proportional inclusion of foreign substances or contaminants in such a way that the end products made from it, in particular stones suitable for landfill purposes, have a high degree of resistance to dilution by groundwater. These stones are therefore particularly suitable for the installation of landfill ventilation, landfill boundaries and the like. The recycling plant according to the invention achieves the great advantage that plastic waste of the most varied types of plastic can be disposed of easily and without harming the environment in the form of the end products now obtained, and these can also be used to create and ventilate landfills. This results in a high degree of economic efficiency because previously such ventilation and boundary stones for landfills had to be manufactured from valuable raw materials such as Portland cement and pre-classified aggregates at great expense. In the end, the economical recycling process is closed with the plant according to the invention, in that landfill elements for waste are obtained from waste.

Claims (3)

PROTECTION CLAIMS 1. Recycling plant for the production of products from plastic waste, characterized in that it comprises the following plant components; a) a processing station for hospital hazardous waste with a mechanical plastic sorting device (1), a downstream plastic coarse shredding device, preferably having a shredder (2), and downstream of this a plastic chip disinfection device (13) with a downstream, preferably transportable coarse material storage device (3a); b) a domestic waste processing station, comprising a feed hopper (14), a connecting hand-picking belt (4) for manually picking out plastic parts, a downstream plastic coarse shredding device, preferably having a shredder (5) with an associated, preferably transportable coarse material storage unit (3b); c) a central processing station comprising a storage silo (16) for mixed plastic raw material, a fine-grinding device preferably having a grinding device (6) with a connected fine material silo (15), an extrusion device arranged downstream of this, preferably having a twin-screw extruder (7) with a cooling section connected to it, preferably having a cooling calender (8), a diathermy system (9) immediately following this and equipped with means for generating an RF field, which is followed by a granulator-cutting machine (10) producing pellets; a storage silo (17) for pellets, and finally a final station with an end product production device (18) for producing end products from pellets, and in some cases with an adjoining finished product storage facility (19). 2. Plant according to claim 1, characterized in that the end product manufacturing device (18) comprises an injection molding machine (11) with means for molding the end products. 3. Plant according to claim 1, characterized in that the end product manufacturing device (18) has a machine system known per se for producing, for example, shaped bricks using hydraulic binding agents which bind the pellets, such as Portland cement, HO slag, water-insoluble mortar, etc.