Drives & Controls March 2023

36 n BELTS, BEARINGS AND CHAINS March 2023 www.drivesncontrols.com Is rubber still the best choice for recycling plant conveyor belts? R ecycling facilities are facing major challenges caused by soaring operating costs, especially during the global energy crisis. Plant managers worry whether recycling is still good for the environment as the costs and energy consumption may outweigh the benefits. However, some do not realise is that many of their challenges can be overcome by using the right belt material. Traditionally, rubber conveyor belts have been the go-to choice for recycling plants because of their high mechanical strength and resistance to abrasion, and they are still used widely. They are ideal for separating mixed waste, especially when materials such as brick, concrete, glass and steel are involved. However, rubber belts have some major drawbacks. They are extremely energy- intensive compared to alternative materials because of their thickness and weight. They are slow to run and the motor power required to move wide, heavy rubber belts, and the increased mechanical strain they put on a system, can raise costs, both in terms of energy use and maintenance. For example, a 3m-wide rubber belt can typically run at 1–1.5m/s, whereas other materials can reach 4–6m/s. Because of their weight, larger pulleys are needed to drive rubber belts compared to similar-sized belts made from lightweight materials. To add to the problem, the added tension on the pulleys increases the energy needed to drive the belt and causes more wear-and-tear on the system, increasing maintenance costs. So, with all the challenges associated with the recycling industry’s traditional belt material of choice, what are the alternatives? Alternatives Lightweight materials, such as polyvinyl chloride (PVC), are becoming increasingly popular for applications such as eddy current separators or general-purpose conveyors. PVC belts are much lighter than rubber belts and use less energy. These factors reduce running costs and a plant’s carbon footprint. While not as durable as rubber, PVC is ideal for transporting materials such as plastics and paper which place less mechanical strain put on a belt than heavier materials such as brick and concrete. However, PVC does not work well if exposed to sunlight and at temperatures below –10ºC. Another alternative is thermoplastic polyurethane (TPU). Generally, TPU belts have the highest upfront costs, but a lower total cost of ownership. TPU belts are extremely lightweight – roughly half as much as similarly sized rubber belts – facilitating faster, wider recycling lines. They have lower energy and maintenance costs than rubber belts, while offering increased throughput. Furthermore, TPU belts are extremely durable and have high abrasion and cut resistance, so can be used with most materials. However, TPU belts also have their downsides. They are not as resistant to hot water as PVC, so are not well suited for applications involving a hot washes – such as the trommel separation of PET plastics where they are used to remove excess debris or labels. Every belt material has its pros and cons, so it is easy to see why recycling plant managers might get confused. However, by consulting with a knowledgeable conveyor partner, they can rest assured that they are using the best belt material for the job. n Traditional rubber belts have limitations when used in recycling plants. What are the alternatives? Marcin Grzeszek, manager for the recycling industry at the belt-maker Habasit, offers advice on choosing the best belt material to help recycling facilities to cut their costs and improve efficiency. The correct choice for conveyor belt materials for recycling facilities can help to cut energy and maintenance costs, and deliver other benefits