Dry fractionation process as an important step in current and future lignocellulose biorefineries: A review

► The choice of pretreatment depends on the heterogeneity of lignocellulosic materials. ► The breakdown of lignocelluloses is a necessary step within biofuel production processes. ► Currently, mechanical size reduction steps are not cost-effective. ► The factors influence the performances of biomass mechanical treatment is discussed. ► Innovative grinding processes or combinations with others pretreatments are required.