Process for reducing specific energy demand during refining of thermomechanical and chemi-thermomechanical pulp

Abstract

A method for producing thermomechanical or chemi-thermomechanical pulp is provided. The process is characterized as having a reduced specific energy demand during refining. The process involves processing a pretreated wood material using one or more high consistency refining steps to produce a first pulp, optionally applying a chelating agent to the first pulp during HC refining to produce a stabilized pulp and treating the first or stabilized pulp with an alkaline-peroxide liquor to produce a treated pulp. The treated pulp is then processed by one or more second low consistency refining steps. Alternatively, the first pulp or stabilized pulp may be divided into a primary and secondary stream. The primary stream is treated with alkaline-peroxide liquor to produce a treated pulp. The secondary stream is processed using a secondary HC refining step to produce a partially refined pulp, and removing latency of the partially refined pulp and the treated pulp is removed in a common location. The treated pulp and the partially treated pulp is processed by one or more than one second low consistency refining step to produce a final pulp. The methods utilize less energy when compared with a method for producing pulp that requires both primary and secondary high consistency refining stages.

Dependencies are inferred from the claim text.