Liquefaction biomass processing with heat recovery

Described are processes that include the non-enzymatic, hydrolytic liquefaction of lignocellulosic biomass to form digest slurries and heat recovery from such digest slurries. Due to enhanced flow properties of the digest slurries such heat recovery can be efficiently conducted in spiral, plate and frame or other heat exchanger designs, with the recovered heat going to unit operations of the process such as heating incoming pretreatment media for the liquefaction. Processes can also involve additional hydrolytic digestion of some or all of the initial slurry components with enzyme and/or additional heat recovery from the initial slurry by direct contact heat exchange in which a portion of the digest slurry liquids is flashed to vapor and that vapor is condensed onto incoming lignocellulosic biomass to the process. Processes as described can be integrated into ethanol manufacture by fermentation of sugars from the digested compositions.