| 摘要 |
FIELD: chemistry.SUBSTANCE: invention relates to a method for continuous precipitation of lignin from black liquor, wherein pH of the black liquor is lowered to the lignin precipitation point and the precipitated lignin is separated from the black liquor. The black liquor is fed so as to flow as a pressurised stream in a reactor (2) with a dwell time of less than 300 s; an acidifying agent selected from a group consisting of carbon dioxide, an acid and combinations thereof is fed to the stream at one or more feeding points (2a) in order to lower the pH of black liquor; the pH is allowed to decrease under the effect of the acidifying agent in the pressurised stream to the lignin precipitation point; the pressure of the pressurised stream is abruptly released, and lignin particles are separated from black liquor.EFFECT: method enables to obtain lignin with high output, having a suitable particle size with a short dwell time and at an industrial scale with low operating costs, which enables to quickly change process conditions.15 cl, 5 dwg, 1 tbl |
