The effect of temperature and moisture on the chosen parameters of briquettes made of shredded logging residues

Highlights: • Shredded logging residues requires specific parameters of briquetting. • Increasing temperature positively affects material's susceptibility to compaction. • The highest densities were obtained for the lowest material moisture of 10%. • Increase in temperature and moisture cause increase in durability of briquettes. -- Abstract: The aim of this work was to determine the effect of compaction parameters of shredded logging residues on the durability of obtained briquettes. Logging residues have a different composition than raw materials currently used in the agglomeration process, because they contain a high amounts of bark, needles and mineral contaminations. The innovation of this study results from the type of biomass used in the research – non-homogenous fraction containing significant amounts of needles and non-woody parts. Correlation between the physical properties of obtained briquette and raw material parameters and the course of briquetting process were determined. Biomass was compacted in a special designed closed die. The investigated material with moisture contents of 10, 15, 20% was compacted at temperatures of 22 and 73 °C. Single briquettes with a density from 799 to 1215 DM kg·m⁻³ at the compaction index values ranging from 27.73 to 35.37 (J g⁻¹)/(g·cm⁻³), respectively were obtained. For both temperatures 22 and 73 °C, the highest values of durability coefficient were obtained for 10% moisture content and they were 16% and 22%, respectively which were not satisfying durability. It was also found that the temperature of material during agglomeration influences its susceptibility to compaction and durability of obtained briquettes and that it is more advantageous to carry out the compaction at a higher temperature. On the other hand, the higher temperature of the agglomeration process affects the increase in specific work of compaction which to a small extent depends on the moisture content of the material.