| 摘要 |
The present invention relates to a process for treating white liquor, which apart from mainly sodium sulphide, sodium hydroxide and water, also contains ions of transition metals and/or alkaline earth metals, in pulp and paper mills. According to the invention, the white liquor is treated on the one hand in a stage a), in which the white liquor is oxidised by first being contacted with an oxygen-containing gas for oxidising sodium sulphide to sodium thiosulphate, after which the white liquor is contacted with hydrogen peroxide for oxidising sodium thiosulphate to sodium sulphate, and, on the other hand, in a stage b), in which a magnesium salt is added to the white liquor and the formed precipitate is separated from the white liquor, the stages a) and b) being carried out in an optional order. |
