Process for pretreatment of lignocellulosic biomass into inorganic salts hydrate

The invention relates to a lignocellulosic biomass processing method comprising at least: a) a step of suspending the lignocellulosic biomass in a liquid medium comprising at least one hydrated inorganic salt, b) a step of solid-liquid separation carried out the suspension obtained in step a) for obtaining on the one hand a solid fraction and secondly a liquid fraction, c) at least one step of baking the solid fraction obtained in step b) in a liquid medium comprising at least one hydrated inorganic salt, d) a step of solid-liquid separation applied to the mixture from step c) firing to obtain firstly a solid fraction and secondly a liquid fraction ; the method being characterized in that the liquid phase of the mixture obtained in step c) has an inorganic salt concentration greater than that of the liquid phase of the suspension obtained in step a); said inorganic salt concentration of the mixture obtained in step c) being at least 45% by weight.