Pulp delignification and bleaching process comprises treating raw material with magnesium or calcium compounds to reduce heavy metal content

摘要

The raw material is treated in a liquid environment with magnesium and/or calcium oxides and/or carbonates in order to remove heavy metals. A process for delignifying and/or bleaching raw materials (e.g. straw), lignocellulosic material (e.g. wood) and refined pulp, preferably used to produce newsprint, copier paper, hygiene products or card, comprises reducing the heavy metal content of e.g. manganese, iron and copper prior to delignification and/or bleaching. The material is treated in a liquid environment with magnesium and/or calcium compounds in the form of oxides and/or carbonates. Excess liquid is then removed.