Metso Chemical Pulping Oy

Valmet Chemical Pulping Oy

Thomas Fant

Mikael Svedman

Panu Tikka

Seppo Martikainen

A method for preparing pulp from lignin-containing cellulosic material is disclosed, including a step for acid cleaning of the lignocellulosic material, followed by alkaline delignification. The acidic step removes undesired components such as metal ions and side groups of polysaccharides, which may have adverse effects on the process especially when extensive recycling of liquors is employed within the plant.

Method for the production of precleaned pulp

A process for the production of pulp using alkaline delignification is disclosed, wherein cellulosic material is initially treated with steam, and a chelating agent is added in connection with the steam treatment. The end pH of the steam treatment stage is below 5. Liquors containing chelated, so-called non-process compounds are not recycled in the pulping process, but expelled therefrom for further processing where non-process compounds are eliminated.

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Böle, Finland

Thomas Fant