Process for producing mechanical pulp suitable for paper or cardboard making

US8764936B2 · kind B2 · utility

Assignee

• M-real Oyj · FI

Inventors

• Auli Laurila-Lumme · Lohja, FI
• Markku Leskelä · Espoo, FI
• Kristiina Manninen · Lohja, FI
• Ole Nickull · Vogtei, DE
• Isto Nikamaa · Kouvola, FI
• Marko Pekkola · Lappeenranta, FI
• Maija Pitkänen · Jyväskylä, FI
• Pirita Suortamo · Jyväskylä, FI
• Kai Vikman · Pertunmaa, FI

Key dates

• Filing date: May 3, 2006
• Grant date: Jul 1, 2014
• Expiry date: Jan 6, 2030

Classification

• Technology area (CPC D): Textiles; Paper
• CPC primary: D21D5/02
• WIPO field: Textile and paper machines
• WIPO sector: Mechanical engineering

Abstract

Method for the production of mechanical or chemi-mechanical pulp as raw material for paper or cardboard. According to this method, the pulp is fibrillated and the fibrillated pulp is bleached in alkaline conditions. According to the present invention, the pulp is screened to separate the reject from the accept, at maximum approximately 60% of the total amount of pulp is separated as the reject, the reject is bleached separate from the accept, and, after that, the bleached reject is remixed with the accept. When operating according to the present invention, the strength of the pulp increases and the energy used for refining is reduced, which is seen both in the refining of the reject and in the post-refining of the final mechanical pulp.