A research on the pelleting of various agricultural residues and determination of pellet physical properties

In this study, pelleting of sesame and cotton stalks obtained from agricultural areas were aimed. In the experiments, pelletting machine with 15 kW electric motor power, 8 mm die diameter and 70-100 kg/h capacity for pelleting of raw materials was used. The experiments were conducted in three different moisture content (cotton stalk: %10.70 (P1), %15.14 (P2), %20.37 (P3) and sesame stalk: %10.67 (S1), %14.88 (S2), %20.22 (S3)) of dried-ground sesame and cotton stalks and liquid molasses mixtures (15 kg raw material + 1.125 kg molasses (7.5%)). The physical properties of pellets such as bulk density, particle density, durability resistance, shatter resistance, compressive resistance, tensile strength and moisture sorption resistance were determined. Also, average capacity of pelleting machine and its energy consumption values were measured. Before testing, the pellets were kept in a room at 22ºC temperature and 60% relative humidity during 7 days for ensure their stabilization. At the end of the study, pellets were produced with a diameter range 8.1 - 8.97 mm depending on material type and moisture content. The bulk density and particle density of pellets were between 430-717 kg/m3 and 922-1368 kg/m3 depending on material type and moisture content, respectively, and pellet densities were decreased with increasing moisture content. The result of physical tests showed that the produced pellets were quite strong due to durability resistance, shatter resistance, compressive resistance, tensile strength and moisture sorption resistance and the highest values were obtained in P1 pellets for cotton stalk and S2 pellets for sesame stalk. The average production capacity and energy consumption of pelleting machine were found between 131-306 kg/h and 18.40-22.64 kWh depending on material type and moisture content, respectively.