| 摘要 |
When closing the process of manufacturing cellulose pulp of high brightness, i.e. including the recovery of essentially all waste liquor, there is an untenable enrichment of certain basic elements, such as sodium and sulphur. The present invention provides a partial solution to this problem and is concerned with a method in bleaching with ozone lignocellulosic material (cellulose pulp) which has been at least partially manufactured chemically, in the presence of water at a degree of acidity, expressed as pH, of 2-5. The method is characterized in that the acidity is maintained during the ozone bleaching process by adding a sulphuric acid solution or an acid sodium sulphate solution produced by electrolysis (or electrodialysis) of an essentially neutral sodium sulphate solution obtained by recycling chemicals in a system to which rest solution (waste liquor) from the ozone bleaching process is added. |
