Abstract: The invention relates to a method of bleaching and/or delignifying cellulose, in which (a) a sodium hydroxide solution and a peroxydisulphate solution are first of all produced by electrolysis of a sulphate, (b) the peroxydisulphate solution is converted by hydrolysis into a Caro's acid/caroate solution, (c) said Caro's acid/caroate solution is left to cool and (d) used immediately as a bleaching solution for bleaching and/or delignifying cellulose, the Caro's acid/caroate solution becoming neutralised upon introduction into the bleaching solution.

Abstract: The invention relates to a method of bleaching and/or delignifying cellulose, in which

Abstract: For bleaching natural chalk, an aqueous suspension consisting of 50 to 80% by weight fine-grained natural chalk and 50 to 20% by weight water and containing 0.1 to 1.5% by weight, based on the dry weight of the chalk, of a dispersant and optionally containing a hydrogen peroxide stabilizer or activator or a salt of hydrogen peroxide with a divalent metal is prepared, the suspension is wet ground to reduce the particle size until about 9/10 of the particles have a grain size of <4, the suspension is mixed with hydrogen peroxide or a salt of hydrogen peroxide with a divalent metal at temperatures between 50.degree. and 99.degree. C. and at a specific pH-value or at an alkaline pH, respectively, and stirred intensively until it is mixed and foaming commences, the suspension is allowed to stand until foam formation is complete and then the foam formed is separated with the dark particles contained therein.