chemical and refining energy consumption as well as vapor and liquid effluent pollution are significantly reduced application_number US 53696783 A description referring first to fig1 green wood chips are fed through line 10 to an impregnation vessel 12 containing an aqueous solution of a loweralkanolamine such as monoethanolamine which serves to pre treat the chips so as to soften the lignin therein make up solution of the amine is fed via line 14 and the pre treatment liquor is heated with steam fed through line 16 sand dirt rocks and the like are removed from the vessel via line 18 when the pre treatment is carried out under pressure vent gases can be directed to a heat recovery unit via line 19 after impregnation the chips are passed to a conventional drainer 20 which may include a screen or perforated bottom conveyor so as to drain away excess pre treatment liquor and are then optionally fed to a conventional press 22 such as a screw press disc press drum press or the like to remove more pre treatment liquor from the chips and to obtain chips having a high oven dry wood content the spent liquor removed from the drainer 20 and optional press 22 is recycled via line 24 to the impregnation vessel 12 to recover chemicals water and heat after pressing the impregnated chips are fed to a cooking vessel 26 for treatment with conventional pulping.