| 摘要 |
1. Process for grinding and washing a cellulosic material for the preparation of a paper pulp by passing the material, reduced in size to chips and impregnated with a reagent for removing lignin in a machine comprising at least two parallel screws driven in rotation inside a casing and provided with helical flights the pitches of which vary so as to determine several successive treatment zones, each zone including a section for conveyance and progressive compression and a braking section constituted by flights of inverted pitch provided with apertures allowing downstream passage of the material, having a size which is adjusted to allow selective advancement in the downstream direction of the material as a function of the degree of grinding achieved upstream of said apertures, characterised by the fact that the grinding and the washing of the chips is carried out simultaneously in the successive treatment zones of the machine, the casing of which is, for this purpose, constituted by an alternating series of filled regions and filtering regions, covering, respectively, the upstream portion and the downstream portion of each section for conveyance, each filled region being extended into the preceding braking section, the material being subjected as it passes from upstream to downstream in the machine whilst passing through each treatment zone, successively to a dilution by carrying out mixing with an actual washing liquid introduced upstream of the treatment zone then, into the flights of the screws to alternation between relaxation phases and phases of increase in pressure and finally to a drainage operation carried out at the same time as the grinding downstream of the section for conveyance and in the braking section, the used liquid being evacuated through the filtering regions of the casing. |
