Patent ID: 7445691

Claim:
A method for a pre-treatment of chips, comprising: exposing the chips to an acidic treatment device by adding an acidic treatment fluid to establish an acidic slurry having a fluid fraction exceeding 50%; draining an acidic fluid from the chips so that the drained chips obtain a remaining free acidic fluid fraction surrounding the chips that does not exceed 10% by volume excluding any chip moisture disposed inside the chips; heating the drained acidic fluid to a temperature in a temperature range of 20-80° C.; recycling the drained acidic fluid directly to the acidic treatment device without adding or removing substances from the drained acidic fluid; adding additional acidic treatment fluid to the acidic treatment device only in a replacement amount that corresponds to an amount of acidic fluid that is retained in the drained chips; heating the drained chips by steam to a first temperature; and heating the drained chips to a second temperature not exceeding 140° C. while adding an alkali impregnation liquid, the second temperature being higher than the first temperature.