Contract n° BOS-043-F

Summary

This study is attached to a great development on the perfecting of a new technology using a bi-vis extruder for the manufacture of bleached high yield pulps:

• with investments and exploitation costs reduced

• using softwoods and hardwoods

• allowing an aqueous effluent treatment

A bi-vis pilot plant having a capacity of 400 kg/h has been installed at Lancey mill (AUSSEDAT REY Company). This unit running continuously can produce mechanical or chemimechanical pulps unbleached or bleached from softwoods or hardwoods.

The objectives aimed are following:

• improvement of the pulp quality by optimisation of several steps of the process and particularly the chips impregnation and cooking, the refining and the bleaching,

• manufacture of bi-vis pulps lots for using in the manufacture of newsprints and printing grades on an industrial paper’machine, the bi-vis pulps taking the place of a part of conventional mechanical pulps and chemical pulps in the the paper compositions.

The work presented in this study comprises the following parts:

• optimisation of the step chips impregnation and cooking with a sodium sulfite solution,

• bleaching study of the pulps in the bi-vis machine: trials with bleaching effluent recycling,

• manufacture of softwoods and hardwoods bleached bi-vis pulps lots,

• manufacture of newsprints with bi-vis pulp on an industrial paper machine- and newspaper printing,

• manufactures of printing grades with bi-vis pulps on industrial paper machines in several mills.