The processing and recycling of fluorescent tubes require a carefully designed, multi-step approach to efficiently separate and recover valuable materials, including metals, rare earth elements, glass, and plastics.
By Al Pena
Fluorescent tubes contain various metals, rare earths, and other materials that can be separated and reused through recycling. However, to achieve the separation into a magnetizable fraction, a non-ferrous metal fraction, a glass fraction, and a plastic fraction, a suitable separation process is required. High recovery rates combined with a high degree of purity are of central importance.
Process Step 1: Screening Technology
As with most separation processes, efficient screening forms the basis for all further processing steps. It is recommended to implement a protective screen after the material has been shredded. The control screening machine helps to remove disturbing long parts (at a screen cut of 50 mm; see Figure 1) and to keep the longs safely away from the undersized fraction.
A waste screen in a flat design without steps and equipped with specially designed louver-type panels ideally meets this requirement. Waste screens are flat screen designs with an unbalanced shaft. The screen panels are arranged in cascades and their louver-like design allows for maximum screen openings, guaranteeing a nearly non-clogging operation. Diverging bars loosen the material and prevent covering of the screen decks. In addition, the design of the waste screen allows the material to be distributed evenly over the required width, which facilitates the treatment on the downstream equipment.
Images courtesy of IFE Material Handling.
Process Step 2: Magnetic Separation Technology
When the shredded and screened material (grain size < 50 mm; see Figure 2) was placed on a barium ferrite drum and a high-intensity drum (neodymium) as part of a material test, it showed that a strong neodymium magnetic drum type KHP is the right choice in order to also split off the small ferrous wires that were still present within the material. Magnetic drum separators are used to separate tramp iron from bulk material of all kinds. Bulk material is fed via a chute or vibrating feeder to the separator and is conveyed by the rotation of the drum casing. Magnetic particles are attracted by the internal permanent magnet, whereas nonmagnetic particles follow their flight path determined by inertia and gravity. The attracted material is conveyed by the drum shell to the end of the magnetic field and dropped to the other side of an adjustable splitter. A large content of magnetizable material (23 percent) is regained by choosing this method.
Process Step 3: Eddy Current Separation
The remaining mixture of fractions (non-ferrous metals, glass, and plastics) is then fed onto an eddy current separator. In this process, the non-ferrous metals contained (11 percent) have been separated. The residuals (glass and plastics; see Figure 3) can be separated again with additional sensor sorting technology. An alternative option is to split the remaining fines from the glass with the help of a flip-flop screen that is suited for difficult to handle material. These screens perform outstandingly where the decks of conventional screens clog or stick.
After the multi-stage separation process has been completed, the fluorescent tube mixture is optimally fractionated and prepared for further processing.
A Comprehensive Approach
The processing and recycling of fluorescent tubes require a carefully designed, multi-step approach to efficiently separate and recover valuable materials, including metals, rare earth elements, glass, and plastics. The process begins with screening technology, which lays the groundwork by removing large contaminants and ensuring that materials are evenly distributed for subsequent treatment. Next, magnetic separation technology uses high-intensity neodymium drum magnets to effectively isolate ferrous components from the shredded mixture, capturing a significant percentage of magnetizable material. This is followed by eddy current separation, which effectively extracts non-ferrous metals, allowing the remaining glass and plastic fractions to be further refined through additional sorting methods, such as sensor sorting or flip-flop screens for challenging materials. Together, these methods optimize the separation and purity of each recovered fraction, ensuring that materials from fluorescent tubes are effectively prepared for reuse and further processing. This comprehensive approach not only enhances recycling efficiency, but also supports sustainable resource management by maximizing material recovery from these complex products. | WA
Al Pena is the North American Sales Manager for IFE Material Handling NA Inc. He is a seasoned sales executive with a background in industrial sales. With his natural ability to understand customer needs, he has been able to build strong client relationships during his career. IFE stands for high quality, long-term solutions, partnership-based relationships, and finding solutions that are also outside the box鈥攙alues and mindsets with which he also strongly identifies. Al can be reached at (905) 228-2094 or e-mail [email protected].