Patent ID: 7709042

Claim:
A process for producing a pretreated feedstock comprising: a) providing a feedstock selected from the group consisting of grasses, cereal straws, stover, and combinations thereof, wherein at least 80% of the feedstock has a particle length of between about 2 and about 40 cm; b) wetting the feedstock in an aqueous stream at about 0.25 to about 10 times the maximum water holding capacity of the feedstock to produce a wet feedstock; c) pressing the wet feedstock through one roll press or a series of roll presses to remove at least a portion of water and soluble substances from the wet feedstock and to shear the wet feedstock to produce a pressed feedstock having a particle size such that, when the pressed feedstock is slurried to produce a slurried feedstock, the slurried feedstock is capable of being pumped at a dry solids concentration of about 8% to about 20%, wherein the one roll press, or one or more than one roll press in said series, comprises rolls with circumferential v-shaped grooves, and wherein the pressed feedstock has a consistency of at least about 35% dry solids after passing through a nip point in the one roll press or a nip point in one or more than one roll press in said series; d) slurrying the pressed feedstock particles to produce a slurried feedstock having a dry solids concentration of about 8% to about 20% and pumping the slurried feedstock into a pretreatment reactor; and e) carrying out dilute acid pretreatment of the slurried feedstock, at a temperature of 160° C. to 280° C. to produce the pretreated feedstock.