The influence of moisture on the sieving performance of lignocellulosic biomass

Abstract

Sieving is an important operation for sorting solid particles both in industry and the laboratory. Although sorting is necessary for almost every process or energy conversion applied to biomass materials, sieving has not received enough scientific attention. The aim of this study was to obtain experimental data on the sieving performance of biomass materials. Three different biomasses – two wood pellets from the same species but each one obtained from a different process, plus a poplar sawdust residue – were sieved using a laboratory sieve shaker before milling with a hammer mill. Samples with three different levels of moisture were also studied: non‐dried, dried for 1.5 h at 75 °C, and dried for 3 h at 75 °C. The results were unexpected because the three samples showed quite different behaviors. A slight drying before sieving significantly enhanced the sieving performance of one of the wood pellets but its effect on the poplar sawdust was just the opposite; in the case of the other type of wood pellets, the effect was intermediate, because it improved the sieving performance but only for a short time and for the finest fraction. These results suggest the importance of conducting a preliminary study of the material to be sieved to save energy, time, and effort. Further research in this area is still necessary to understand the influence of variables in order to reduce blinding during biomass sieving.