Drum screen with elongated slots for plastic separation

Abstract

A drum screen apparatus has a cylindrical body configured for rotational motion and a plurality of elongated apertures or slots formed in the cylindrical body. The drum screen equipment can be used for sorting fragments of automobile crushing residues.

Description

[0001] Statement on Related Patent Applications

[0002] This application claims the benefit of U.S. Provisional Patent Application No. 63 / 432,634, filed December 14, 2023, which is incorporated herein by reference in its entirety. Technical Field

[0003] The present application relates to separation equipment. Background Art

[0004] A trommel, or rotary screen, is a mechanical device used to separate materials, primarily in the minerals and solid waste industries. It features a perforated cylindrical drum, typically angled at the feed end. As the feed descends along the rotating drum, material separation occurs, with smaller particles passing through the mesh and larger particles exiting at the opposite end.

[0005] While not typically associated with plastics, trommel screens are widely used in municipal waste management to sort solid waste by size. They also enhance fuel recovery from solid waste by removing inorganic materials such as moisture and ash from the air-sorted light fraction of pulverized solid waste, thereby improving fuel quality. Trommel screens also have applications in wastewater treatment, where they help separate solids from liquid streams. When the liquid reaches a set level, the screen rotates, with solids accumulating on the screen mesh and being conveyed for further processing.

[0006] The screens in trommel screens are typically made of perforated plate or mesh. Perforated plate screens, manufactured through rolling and welding, offer strength and fewer ridges, simplifying cleaning. In contrast, mesh screens, while replaceable and more susceptible to wear, require more intensive cleaning due to objects becoming lodged in the mesh ridges. The screens are often uniform or irregularly shaped, making them less suitable for plastic separation.

[0007] Therefore, there is an ongoing need for an improved trommel screen. Summary of the Invention

[0008] The present application discloses a trommel screen apparatus having a cylindrical body configured for rotational movement and a plurality of elongated holes or slots formed in the cylindrical body.

[0009] One aspect is a trommel screen apparatus comprising: a cylindrical body configured for rotational motion; and a plurality of elongated holes or slots formed in the cylindrical body. The elongated holes or slots may be oriented longitudinally along the axis of the cylindrical body. The elongated holes or slots may have an aspect ratio greater than 3:1, greater than 4:1, or greater than 6:1. The elongated holes or slots may be arranged in a spiral pattern along the cylindrical body. The edges of the elongated holes or slots may be reinforced.

[0010] Another aspect includes a method for separating materials using a trommel having elongated slots. The method may include providing a trommel apparatus having a cylindrical body configured for rotational motion and a plurality of elongated holes or slots formed in the cylindrical body; providing a material comprising plastic into the rotating cylindrical body; introducing the material into the rotating cylindrical body; and allowing smaller material to exit the cylindrical body through the elongated holes or slots. The material may comprise plastic or may be automotive shredder residue. BRIEF DESCRIPTION OF THE DRAWINGS

[0011] Figure 1 is a perspective view of one embodiment of a trommel screen featuring a cylinder having elongated slots as described in this application;

[0012] Figure 2 Yes Figure 1 a perspective view of the cylinder depicted;

[0013] Figure 3 yes Figure 2 a perspective view of a section of the cylinder shown; and

[0014] Figure 4 is an illustrative diagram illustrating a method related to the present application. DETAILED DESCRIPTION

[0015] The present application describes the specific embodiment of a trommel, which is designed to sort, grade and separate mixed solids of various sizes (with a large amount of plastics) in many applications. The device can have a rotating drum or cylinder equipped with circumferentially arranged elongated bars or slots. These bars are spaced apart to allow objects of desired size to pass through for collection. In essence, the trommel or trommel equipment described here is a cylindrical screening device, mainly used to separate materials containing a large amount of plastics. Incorporating elongated slots in the design of the trommel or trommel equipment helps to improve the efficiency and precision of the material separation process.

[0016] Figure 1A trommel or trommel screen apparatus (10) is shown which consists of a cylindrical body (20) typically constructed of a durable metal such as steel or aluminum. The cylinder is located in a frame (30). The length and diameter of the cylinder may vary based on the intended use and capacity requirements. The surface of the cylindrical body (20) has a screen (50) with elongated slots. These slots are oriented longitudinally parallel to the axis (A) of the trommel. The aspect ratio of the slots is optimized to help ensure efficient sorting of material while minimizing clogging. The edges of the slots or bars or screen (50) may be reinforced to resist wear.

[0017] A drive motor (not shown) rotates the drum body (20) via a shaft operatively connected to the drum, which can be controlled via an interface or switch (40). The trommel or trommel screen apparatus (10) is mounted on a horizontal axis and powered by an external motor. This motor facilitates the rotational movement of the trommel or trommel screen apparatus, which is essential to the screening process. The speed of rotation can be adjusted depending on the material being processed.

[0018] Figure 2 A perspective view of a cylinder body (20) equipped with screens (50) is presented. These screens are designed to allow plastic solids of a specific size to pass through based on their mesh spacing. In order to prevent or reduce mesh clogging and minimize downtime, a brush can be applied to the screen. In certain embodiments, these screens feature elongated slots that allow flat materials of a specific size to pass through them.

[0019] In this example, the sorting device or drum screen or drum screen apparatus (10) features a drum having elongated slots spaced at various distances (e.g., approximately 3 inches, 4 inches, 6 inches, 8 inches, 10 inches, 12 inches, or more). These slots are designed to selectively allow flat particles to pass through. The drum screen or drum screen apparatus (10) retains the larger three-dimensional or less flat particles on top of the screen while sorting out the flatter particles. Despite their larger size, these flat particles can pass through the slots because their thickness is minimal compared to their other two dimensions. The drum screen sorter is designed to utilize centrifugal force or elevators. These mechanisms lift the particles so that they repeatedly fall onto the slotted screen deck. This repeated reorientation increases the chances of the flat particles being vertically aligned, thereby allowing them to pass through the slots in a flat orientation.

[0020] Figure 3An example of a screen (50) designed to be mounted on a cylindrical body (20) is illustrated. The figure highlights how rods (60) are used to form slots, each having specific width and length dimensions. Additionally, the screen (50) may include reinforcements (55) to increase stability and durability. Slots (70) are depicted as the spaces between the rods (60).

[0021] Figure 4 A method 200 for recycling waste materials using a trommel equipped with elongated slots is depicted. The method includes the following steps: first, providing a trommel apparatus featuring elongated slots (210); second, adding a material containing plastic to a rotating cylindrical body of the trommel (220); third, adding additional material to the rotating cylinder (230); and finally, allowing smaller materials to exit the cylindrical body through the elongated holes or slots (240).

[0022] In their operation and use, the trommel or trommel apparatus is effective in sorting lightweight materials, particularly plastics. The material is fed into the higher end of the trommel or trommel apparatus. As it rotates, smaller particles are able to fall through the elongated slots, thereby being separated from the larger items. The sorted material is then collected at the lower end of the trommel or trommel, or via a conveyor located below the slots. Specifically, flexible materials such as rubber pass through, while three-dimensional objects such as rubber hoses, tire rubber, wood, etc. are filtered out. The incorporation of elongated slots brings several benefits, such as improved sorting accuracy, reduced likelihood of clogging, and increased processing capacity. In addition, the design excels at handling a wide variety of materials, including those that are wet or sticky. An important application of such a sorting machine is the separation of plastics from waste materials.

[0023] In one embodiment, these processes and systems have been found to be very effective in recovering plastics from waste materials that are extracted as waste (which is common in the EU without incineration). Extractors are well known in the field of sorting and produce a light fraction containing organic material that has limited amounts of metals, and this metal is often buried, embedded, or entangled with organic fibers. Typically, the fiber raw material has plastic buried, embedded, or entangled.

[0024] The waste material may have less than 60%, 50%, 40%, 30%, 20%, 10%, 6%, 5%, 4%, 3%, 2%, or 1% plastic by weight or volume. In some examples, the fibrous lightweight material contains greater than 95% plastic or organic matter. In some examples, plastic material comprises more than 90% of the waste material, second only to large three-dimensional objects (unshredded material or large objects greater than 5 mm or 6 mm).

[0025] With respect to waste streams, particular embodiments can be used to process waste materials or recyclable materials that contain a plastic concentration greater than 15%, or 25%, 35%, 45% and / or 50%. This means that as long as the plastic concentration is good (as low as 20% or greater), the system can correctly sort the material. Household waste that is pre-sorted into "plastic and non-plastic" streams would be a good example. Typically, household waste that is not landfilled can be pre-sorted at a recycling facility where the plastic separation would take place. This plastic concentrate is an example of a "good quality feed." Municipal waste containing plastics is an exemplary waste stream material.

[0026] In one embodiment, the feed material can be automotive shredder residue (ASR). Automotive shredder residue (ASR), which typically represents 15% to 25% of a vehicle's mass at the end-of-life stage (after becoming an end-of-life vehicle or ELV), is the residual material remaining after processes such as decontamination, dismantling, shredding, and extraction of metals from vehicle bodies. ASR can be divided into three categories: "lights," "heavys," and mineral components. Both light and heavies are distinguished by their high concentrations of combustible materials, including plastics, rubber, and textiles.

[0027] Figure 1 and Figure 2 An exemplary drum screen sorter is illustrated that features narrow slots in which bars extend along the length of the drum screen, supported by circumferential rings. The slot width can range from a quarter inch to an inch in various embodiments, or any increment within that range. The slot length varies between 3 inches and 24 inches, with increments selectable within that range. These dimensions are carefully selected to optimize plastic recovery in the waste stream. In some designs, the longer dimension of the slot is 2 to 8 times the size of the plastic fragments being sorted. In one example, the longer dimension can be 2-8 times, 3 times, 4 times, 5 times, 6 times, 7 times, or 8 times the size of the plastic drop.

[0028] Different elements or components of the module are constructed using different construction materials such as stainless steel, mild steel, etc.

[0029] As can be seen, a trommel or trommel screen apparatus can be optimized in various ways. For example, the size of the elongated slots can be adjusted to accommodate specific material sizes. Additional features such as brushes or scrapers can be added to keep the slots clear. Furthermore, depending on the application, a trommel or trommel screen apparatus can be designed to be portable or stationary.

[0030] Although the specific embodiments of the present disclosure have been described in detail above, this description is for illustrative purposes only. It should be understood that this specification illustrates those aspects of the present invention that are relevant to a clear understanding of the present invention. Certain aspects of the present invention that will be apparent to those of ordinary skill in the art and therefore will not facilitate a better understanding of the present invention are not presented in order to simplify this specification. Although embodiments of the present invention have been described, those of ordinary skill in the art will recognize that many modifications and variations of the present invention may be adopted when considering the foregoing description. All such variations and modifications of the present invention are intended to be covered by the foregoing description.

Claims

1. A drum screen device, comprising: a. a cylindrical body configured for rotational movement; as well as b. A plurality of elongated holes or slots formed in the cylindrical body.

2. A trommel screen apparatus as described in claim 1 wherein the elongated holes or slots are oriented longitudinally along the axis of the cylindrical body.

3. The trommel screen apparatus of claim 1 , wherein the elongated holes or slots have an aspect ratio greater than 3:

1.

4. The trommel screen apparatus of claim 1 , wherein the elongated holes or slots have an aspect ratio greater than 4:

1.

5. The trommel screen apparatus of claim 1 wherein the elongated holes or slots have an aspect ratio greater than 6:

1.

6. The trommel screen apparatus of claim 1 , wherein the elongated holes or slots are arranged in a spiral pattern along the cylindrical body.

7. The trommel screen apparatus of claim 1 , wherein edges of the elongated holes or slots are reinforced.

8. The trommel screen apparatus of claim 1 wherein the elongated apertures are at least 0.75 inches wide.

9. A method of separating materials using a trommel having elongated slots, the method comprising: Providing a trommel screen apparatus according to any one of claims 1; providing a material having a plastic into the rotating cylindrical body; adding material into the rotating cylindrical body; as well as Smaller materials are allowed to exit the cylindrical body through the elongated holes or slots.

10. The method of claim 9, wherein the material comprises plastic.

11. The method of claim 9, wherein the waste material is automobile shredder residue.

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