Method for recycling aluminum alloy wheels

[0001] The invention relates to a method and apparatus for recycling aluminum, and in particular to a method and apparatus for recycling wheels of aluminum alloys.

Background of the Invention [0002] Aluminum has a relatively low density and high strength. Accordingly, aluminum in pure form or in alloys with other metals is used in many cases because it allows the preparation of lightweight structures. For example, this particular feature of aluminum makes it suitable for the production of beverage cans and wheels made of aluminum alloys. With the increasing consumption of aluminum in these fields and the increase in demand for them, it is increasingly important that structures made of aluminum can be effectively recycled.

[0003] Technologies according to the state of the art have created opportunities for aluminum recycling. For example, US Patent 5,133,505 discloses a method and apparatus for separating aluminum alloys from other materials. This invention consists of magnetic separation and subsequent milling. However, for many reasons, the process and device cited in the patent are not perfect when recycling aluminum alloy wheels. Namely, the prior art method and apparatus are not suitable for processing aluminum from a single source, for example aluminum alloy wheels. Furthermore, the state of the art technologies do not provide an effective way to deal with the impurities that may be present on aluminum products, such as aluminum alloy wheels.

[0004] Aluminum car wheels are made of high purity aluminum alloys, often of the Aluminum Association alloy No. A356.2. In addition to high-purity aluminum alloy, car wheels may also include the following materials: paint, colorless coating, lead weights, brass, rubber, brass fittings, stainless steel or iron inserts. If a wheel made of alloy A356.2 is melted, contaminated with too much of any of the above metals, the composition of the melt will differ from the specification of alloy A356.2 and will not be usable when casting new wheels from alloy A356.2. As a result, aluminum alloy wheels are often processed into lower value products. For example, aluminum alloy wheels are often remelted and used in the production of a second quality alloy, namely alloy A356.1 or as an iron thinner in the production of lower purity aluminum alloys.

[0005] The value of alloy A356.1 or iron diluents is lower than that of alloy A356.2. For this reason, when processing aluminum alloy wheels in this way, most of their hidden properties are lost because the processed material has a lower value.

-2 than the high quality aluminum alloy A356.2, which was originally made of aluminum wheels.

[0006] The paint and colorless coating present on the wheels is also a problem when the alloy wheels are re-remelted, for recycling, or when the wheels are first heated to remove impurities, as these impurities release toxic fumes during remelting. Therefore, it is necessary to use purification devices, such as bag filters, which increases recycling costs.

Summary of the Invention [0007] According to a first object of the invention, a method of processing aluminum alloy wheels is provided. The method includes: (a) providing a charge of wheels of aluminum alloys of a particular grade, (c) dividing the wheels of aluminum alloys into multiple pieces; and (d) subjecting these pieces to shot blasting to produce shot pieces.

[0008] According to a second object of the invention, a method of processing aluminum alloy wheels is provided. The method includes: (a) providing a charge of aluminum alloy wheels of a particular grade, (b) subjecting the aluminum alloy wheels to X-ray separation to remove contaminants; (c) dividing the aluminum alloy wheels into multiple pieces; and (d) subjecting these pieces to shot blasting to produce shot pieces.

Brief Description of the Figures [0009] These and other advantages of the invention will become clearer and clearer in connection with the detailed description of preferred examples of the invention and with reference to the figures of the drawings, of which:

Fig. 1 is a diagram showing a method of recycling aluminum alloy car wheels according to a preferred object of the invention; and

Fig. 2 shows the method of recycling aluminum alloy car wheels according to another object of the invention.

Detailed description of preferred aspects of the invention [0010] Fig. 1 is a diagram showing a method of recycling aluminum alloy wheels according to the subject matter of the invention. Alloy wheels can be made of any aluminum alloys that are currently or will be used in the production of vehicle wheels. These vehicles can be passenger cars, trucks, motorbikes, although they are preferably passenger cars.

[0011] To maintain the alloy composition, the wheels that are processed simultaneously are preferably made of the same alloy. At present, alloy 356.2 is used for the production of aluminum car wheels, therefore it is preferable to provide wheels made of alloy A356.2 as process input. However, those skilled in the art will recognize that when different alloys are used to make alloy wheels, the wheels can be sorted into stacks of the same alloy, and each can be processed separately.

[0012] The method starts from step 10, during which the wheels sent for recycling are examined and classified. At the inspection stand, for transporting the material to further stands, depending on the classification of the material at the examination stand, many means of transport are used, preferably drive belts or conveyor belts 12. Any known known alloys can be used to move wheels with a mass similar to that of alloy wheels. means of transport. At the visual inspection stage 10, the fed wheels can be divided and forwarded to the 14 reject area, manual processing area 18, or they can also be directly processed and sent to the crusher 20.

[0013] The wheels sent for recycling are evaluated to determine whether they are sufficiently free of impurities 13, including foreign substances such as lead, brass, stainless steel or iron, which may be present in the form of batteries or other materials from the owner buying scrap metal or garbage such as wood or cardboard. These impurities can affect the chemistry of processed products, so they are removed.

[0014] The chrome wheels are covered with chrome. If too much chrome is added during remelting, the processed alloy will not have the appropriate parameters. For this reason, the chrome wheels are removed at this stage and can be stored for future processing or transfer to another recipient. It should be remembered that several chrome wheels will not significantly affect the composition of the melted alloy. However, it is beneficial to get rid of all chrome wheels at this stage. Such wheels can be transferred to the manual processing area 18 in which they are separated, e.g. an employee manually removes chrome from the wheels and transfers to the storage area. Alternatively, which is not shown, the visual inspection station 10 may be equipped with a separation belt 12 to transport the chrome wheels to a separate storage area. Chromed wheels can be subjected to the rest of the process, while chromium-plated alloy wheels made of an alloy, e.g. 356.2, are not processed.

[0015] The wheels of trucks and motorcycles are usually made of a different alloy. If so, these wheels should also be removed because their presence will change the composition of the alloy being processed. If these wheels are made of aluminum alloy, they can be stored and processed in the machine at a different time to prepare another processed alloy. For example, motorcycle wheels can be separated and stored in the first area for later processing, and truck wheels can be separated and stored in the second area for later recycling. The splitting step can be carried out to prepare several stacks, each of which will contain wheels of the same alloy. These wheels can be sent to the manual processing area 18 in which they will be separated, e.g. manually by an employee who will move the wheels to the storage area. Alternatively, which is not shown, the visual inspection station 10 may be equipped with a separation belt 12 to transport the wheels to one or more storage areas. These wheels can be subjected to the remainder of the process, while other aluminum alloy wheels will not be processed.

[0016] Contaminants 13 are removed, e.g. after placing them on the separation belt 12 and stored in the storage area (step 14), where they can then be collected in step 16. In addition, any wheel that is not suitable for processing (e.g. not made of aluminum alloy), it can also be directed to the 14 reject area.

[0017] Some wheels have a level of impurities that prevents them from being directly processed. Excessive impurities can be removed from the wheels in the manual processing area 18 to prepare the wheels for recycling. After machining, the wheels can be transported to the crusher 20, for example using a transport belt 19.

[0018] At the crushing stage, the recycled wheels are fed to a crusher 20 that is suitable for crushing the wheels to a size that will be the input material to the magnetic separator 24. Any type of crusher known in the art can be used. For example, aluminum alloy car wheels can be fed into the hopper of a conventional crusher, e.g. an SSI 45H crusher from SSI Shredding Systems Inc. from 9760 SW Freeman Drive, Wilsonville, Oregon, 97070-9286, USA. The crusher includes a milling crate in which the milling cutters are mounted, mounted on parallel shafts that rotate horizontally in opposite directions. The charging hopper is located above the chest with cutters. Thanks to the force of gravity, aluminum alloy wheels placed in the basket are fed down to the appropriate place where they are picked up by cutters and cut or torn into small pieces, shredded product 21. Preferably the aluminum alloy wheels are cut into small pieces from two inches to three inches, more preferably about two inches. After shredding the wheels to such a size, impurities in the form of valve stems are released and the corresponding percentage can be removed thanks to a magnetic separator 24, optionally a separator of 28 eddy currents, so as not to change the composition of molten processed aluminum, so that it does not deviate from the specifications of the recycled alloy.

[0019] In addition to preparing two-inch aluminum pieces, the comminution process generates particles and dust. Preferably, the by-products of the grinding process are separated from the two-inch pieces of aluminum by screening. Thus, after the comminution stage, the comminuted product may be fed to a vibrating screen 22 to prepare the processed comminuted product 23, free of this type of material. The vibrating screen has many holes that allow dust and particles to pass through and retain the crumbled material. For example, each hole may be smaller than two-inch pieces to retain them on a vibrating screen, allowing particles and dust to pass through simultaneously. Particles and dust that pass the vibrating screen are preferably recovered by remelting or other process. For example, the particles will usually have a high aluminum content and it is preferred to smelting them for recycling.

[0020] At the magnetic separation stage, the shredded aluminum alloy is fed to a magnetic separator 24, which removes the iron material from the shredded pieces to prepare the shredded product having a limited iron content 25. Such a magnetic separator can be, for example, a magnetic drum having a working beam 180 °. Two-inch pieces are introduced into the drum

-5 aluminum alloy. These pieces, which do not contain a significant amount of ferrous material, pass through the magnetic drum, while those that contain a significant amount of ferrous material stick to the magnetized drum and are removed from further processing. Pieces containing a significant iron content will include pieces having bindings and inserts, for example pads made of iron or steel.

[0021] Optionally, the magnetic separation step can be omitted, provided that the particulate product is mostly free of ferrous material. This can be guaranteed by pre-sorting the alloy wheels so that only pieces that do not contain a significant amount of iron will undergo further processing.

[0022] The shredded product having a limited iron content is fed to a shot blasting device 26. At the blasting stage, aluminum alloy pieces are fed to a shot blasting device suitable for processing pieces of the size of the crumbled product having a limited iron content. For example, the device may be a centrifugal shot blasting device, e.g. model (FB-4/28 / E / MR) Flexbelt ™ system by BCP Wheelabrator with 1219 Corporate Drive, Burlington, Ontario, L7L 5V5, Canada, which is suitable for shot blasting . Preferably, half-inch or larger S330 shots, also available from BCP Wheelabrator, are used.

[0023] Model FB-4/28 / E / MR centrifugal shot blasting device includes a housing that completely closes the transfer means in the form of a plurality of scrapers extending transversely between the continuous chains to follow a fixed path. This casing is divided into four compartments, which include one input chamber, two shot blasting chambers and one shaker chamber. The scrapers in the shot blasting chamber are made of manganese rods resistant to pellets, while the scrapers in the shaker and input chambers can be made of cheaper and less durable materials.

[0024] In the blasting chambers, the abrasive is thrown onto aluminum pieces to clean their surface. Impact of the abrasive on the surface releases residue residue. Then these residues are removed from the system in the shaker chamber, and the used abrasive is returned to the shot blasting wheel. Residues removed by shot blasting include organic compounds, for example paints, a transparent coating and rubber, as well as copper and chromium.

[0025] After the shot blasting step, the cleaned aluminum pieces 27 can be collected and then transferred for use as wheel material in another production operation at step 30. Alternatively, a eddy current separator 28 can be used to further process the cleaned aluminum pieces 27.

[0026] The eddy current separator 28 separates materials based on their density and electrical conductivity, using electromagnetically induced eddy currents to generate repulsive forces between the electromagnet and the material in which the eddy currents are generated. Any type of device known in the art can be used. Usually, in the eddy current separator, a rapidly changing current in the inductor

The separator generates a magnetic field. The magnetic field flux is cut through by conducting material placed in the generated magnetic field. Because the flux changes over time, and the conductive material in the field is unable to bind the time-varying flux, current is generated in the conductive material to generate a net zero stream that passes through the conductive material. A current called eddy current has a magnetic field associated with it. The magnetic field exerts a repulsive force on the first magnetic field. Thus, because the electromagnet is placed in a fixed position, the material in which the eddy current has been induced will be pushed away from the electromagnet, while the other non-conductive materials can move freely. The repulsive force will change directly with the value of the eddy current, which in turn varies depending on the electrical conductivity of the material. The effect of repulsive force will of course depend on the density of the pieces it affects.

[0027] This is an optional step, the cleaned aluminum pieces 27 pass through a high unidirectional magnetic field. The direction of movement of the pieces is about 90 ° in relation to the direction of the field. As described above, pieces with higher conductivity will be rejected to a greater extent than those with lower conductivity. Pieces that have a lower density will respond to generated repulsive forces more than those with a higher density. Thus, many pieces will be separated based on relative conductivity and density.

[0028] The cleaned aluminum pieces 27 may vary in density and conductivity due to the presence of other materials. For example, aluminum alloy wheels may include, but are not limited to, lead weights, brass mounts, or stainless steel mounts. The cleaned aluminum pieces 27 may include lead weights, brass housings or stainless steel, and thus differ in average density and conductivity from those cleaned aluminum pieces 27 that do not contain a large amount of this type of material. The cleaned pieces of aluminum 27 of the second type, which do not contain significant amounts of lead, brass or stainless steel, are separated by means of an eddy current separator and transferred to the stage

30.

[0029] When aluminum alloy wheels that do not contain chromium are not processed, the wheels containing chromium or another alloy material can be processed. The steps are essentially the same as those described above, however, the end product is an alloy with a different composition.

[0030] For typical chrome-plated aluminum alloy wheels, the content of non-aluminum components is as follows:

<td>Cu</td><td> 3,5%</td><td>fe</td><td> 0,16-0,20%</td>

<td>mg</td><td> 0,35%</td><td>Ni</td><td> 3,0%</td>

<td>si</td><td> 7,0%</td><td>ti</td><td> 0,15%</td>

<td>cr</td><td> 0,50%</td><td></td><td></td>

[0031] After shot blasting, a sample of the above-described chromium-plated aluminum alloy wheel was analyzed, and its composition, except aluminum, was as follows:

<td>Cu</td><td> 0,60%</td><td>fe</td><td> 0,20%</td>

<td>mg</td><td> 0,28%</td><td>Ni</td><td> 3,0%</td>

<td>si</td><td> 7,0%</td><td>ti</td><td> 0,15%</td>

<td>cr</td><td> 0,009-</td><td> 0,17%</td><td></td>

[0032] The above analysis shows that shot blasting removed most of the copper and chromium, but did not allow removal of silicon, iron, nickel or titanium (silicon, iron and titanium are melted in the metal). As a result, the product was obtained, which is a relatively valuable aluminum alloy containing 0.6% Cu and 3.0% Ni with very low chromium content. This product can be sold to piston alloy manufacturers and is a very good addition to nickel. Thus, the process carried out on chromium-plated wheels makes it possible to obtain processed aluminum of high value, which is suitable for many commercial applications.

[0033] Fig. 2 is a diagram showing the method of recycling aluminum alloys according to another object of the invention. As with the method of Fig. 1, alloy wheels can be made of any aluminum alloys that are currently or will be used in the production of vehicle wheels. Vehicles can be passenger cars, trucks or motorbikes. Preferably they are passenger cars. For the sake of explanation, to designate elements analogous to those shown in Fig. 1 the same reference symbols were used together with the apostrophe. For the sake of brevity, the description of Fig. 1 will not be repeated in relation to Fig. 2.

[0034] As shown, Fig. 2 includes an additional step, where after step 10 ', the wheels undergo X-ray separation in step 32. X-ray separation step 32 consists of x-ray fluorescence. At this stage, a high energy radiation source, for example an X-ray tube or radioisotope source, is set to eject the electromagnetic radiation onto the wheels. When electromagnetic radiation hits a wheel, the wheel will emit fluorescence that will be representative of the materials the wheel is made of. Fluorescence will be captured by a detector, such as a proportional counter or Si (Li) detector. Based on the fluorescence received by the detector, it will be possible to determine the composition of a single circle.

[0035] If it is determined that the wheel contains significant amounts of lead, brass, stainless steel or other impurities, it will be separated from the other wheels by suitable mechanical means, for example a lever that pulls the wheel from the conveyor to the container or by means of an openable flaps on the conveyor so that the wheel falls into the container. Similar to the process described above for stage 10 visual inspection, the supplied wheels can be divided based on information obtained in stage 32

- X-ray separation to the 14 'reject area, 18' manual processing area or for direct processing and sent to a 10 'crusher.

[0036] Preferably, as shown in Figure 2, the X-ray separation step 32 takes place before the separation strips 12 '. Optionally, it can be used to supplement or to some extent replace the 10 'visual inspection. However, optionally, the X-ray separation step can be used to replace the 24 'magnetic separation step or it can be immediately before or after the 24' magnetic separation step. For a description of the magnetic separation technology, refer to (1) US Patent 4,848,590 (Kelly) issued July 18, 1989; (2) US Patent 5,738,224 (Sommer, Jr. et al.) Issued April 14, 1998; and (3) US Patent 4,317,521 (Clark et al.) Issued March 2, 1982.

[0037] Still other modifications and changes of the invention are possible. For example, aluminum alloy wheels can be broken into pieces in many different ways other than by using a crusher. For example, aluminum alloy wheels can be crushed, not crushed. However, crushing can be more expensive because it will be more difficult to separate the other elements from each other. In addition, crushing could result in lower value particles. Although the objects of the invention have been described above that are used for aluminum alloy wheels, it will be appreciated by those skilled in the art that the method may be used to recycle other aluminum components, regardless of whether such components have previously been broken into pieces or not . For example, the methods of the invention may be applied to the recycling of scrap aluminum windows or doors.

Prepared and verified

Anna Stenzel Patent Attorney