The Pelletizability of Tea Waste and the Effect of Moisture Content and Pellet Diameter on Pellet Properties

In this study, the pelletability of tea waste, a by product of tea factories, was investigated, along with the effects of different moisture contents and pellet diameters on the physical and mechanical properties of the resulting pellets. The experiments were conducted using two different moisture levels (8–9% and 11–12%) and three different pellet diameters (6, 8, and 10 mm). The findings revealed that moisture content is one of the most important parameters determining pellet quality. Pellets produced at higher moisture content (11–12%) exhibited significantly better performance in terms of mechanical strength, impact resistance, and fracture resistance under pressure compared to pellets with lower moisture content. Under low moisture conditions, pellets became more brittle, and strength losses were particularly pronounced in larger pellets. When evaluating the effects of pellet diameter, it was determined that as the diameter decreased, the mechanical integrity and strength properties of the pellets increased. Pellets with a diameter of 6 mm yielded the highest quality values, while pellets with a diameter of 10 mm exhibited weaker properties, especially under low humidity conditions. It has been confirmed that moisture content and pellet diameter have significant effects on all parameters defining pellet quality. Correlation and PCA results showed that properties such as mechanical strength, impact resistance, compressive strength, and density changed together and that high moisture–small diameter combinations were associated with higher quality pellets. It can be stated that tea waste can be converted into a high-quality pellet fuel without the use of any binder under suitable conditions, and that a moisture content of 10–12% and a diameter range of 6–8 mm are particularly favorable for tea waste pellet production. These findings point to significant potential for the energy-based utilization of tea waste in regions with intensive tea production.