METHOD FOR MANUFACTURE OF HIGH-YIELD FIBROUS SEMI-FINISHED PRODUCT Russian patent published in 2004 - IPC

FIELD: pulp-and-paper industry, in particular, production of chemical-thermomechanical pulp from wood chips for different kinds of paper and cardboard.

SUBSTANCE: method involves first stage of treating, in screw-type apparatus, wood chips of foliar wood kinds with sodium hydroxide solution of 20-25 g/l concentration at consumption rate of 2.5-4.0% of Na₂O by weight of perfectly dry chips at temperature of 100-120⁰C and pressure of 0.1-0.2 MPa, and second stage of treating with sodium hydroxide solution of 26-30 g/l concentration at consumption rate of 4.5-5.5% of Na₂O by weight of perfectly dry chips at temperature of 150-160⁰C and pressure of 0.40-0.55 MPa. Second stage may be carried out in the presence of sodium sulfite solution of 120-150 g/l concentration at consumption rate of 1.5-2.5% by weight of perfectly dry chips having pH value of 8.0-8.5.

EFFECT: improved environmental ecology owing to reduced content of hazardous substances in sewage and improved physico-mechanical properties of base product.

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