This invention relates to a process of treating a lignocellulosic material to produce bio-
ethanol. The process includes the steps of: (a) exposing the lignocellulosic material to conditions including a pH not less than about 8, and steam at a first pressure, to produce a step (a) product; (b) explosively discharging the step (a) product to a second pressure less than the first pressure to produce a step (b) product; and (c) further 
processing the step (b) product to produce bio-
ethanol and other co-products. In another embodiment, the invention relates to a conical 
auger fractionation column. The 
fractionation column includes a column body having an input and an output. A conical filter is positioned inside the column body, the filter having a larger 
diameter end directed toward the input and a smaller 
diameter end directed toward the output. A conical 
auger is positioned inside the conical filter, the conical 
auger having an outer 
diameter which is approximately the same as an inner diameter of the conical filter. The auger and filter are adapted to cooperate to separate cellulosic solids from a liquid 
stream in a process of producing bio-
ethanol from a lignocellulosic material.