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.