Title (en)

MECHANICAL PULPING

Publication

EP 0138484 A3 19860702 (EN)

Application

EP 84306656 A 19840928

Priority

US 54384783 A 19831020

Abstract (en)

[origin: EP0138484A2] Thermomechanical, chemimechanical, and chemithermomechanical pulps are produced in a manner such that they have enhanced drainage and strength, and/or can be bleached to enhanced brightness levels and in a simple manner. Chips are impregnated with chemical or thermal treating fluid, such as by passing heated sulfite liquor countercurrent to the flow of the chips (at 12). After impregnation, and where applicable cooking, the chips are washed by a countercurrent flow of wash liquid (at 13, 27) including chelating and surface active agents. Immediately after washing the chips are mechanically refined to produce a mechanical pulp by passing the chips through a first pressurized refiner (14, 38), screening (at 15, 39) the pulp discharge from the first refiner to provide first (16, 40) and second (17, 41) streams, passing the first stream to a second pressurized refiner (18, 43) having a discharge (19, 44), and passing the second stream directly to the discharge of the second refiner. Further treatment of the pulp, including bleaching (at 21, 57) utilizing hydrosulfite and/or peroxide, is effected in order to achieve a mechanical pulp having the desired properties.

IPC 1-7

D21B 1/02; D21B 1/12

IPC 8 full level

D21C 3/22 (2006.01); D21B 1/02 (2006.01); D21B 1/12 (2006.01)

CPC (source: EP)

D21B 1/021 (2013.01); D21B 1/12 (2013.01)

Citation (search report)

• [A] EP 0034560 A2 19810826 - BELOIT CORP [US]
• [A] US 4229250 A 19801021 - LEHTINEN ANTTI
• [A] GB 1547939 A 19790704 - CROWN ZELLERBACH CORP
• [A] US 4116758 A 19780926 - FORD MICHAEL J, et al
• [A] GB 785060 A 19571023 - WALDHOF ZELLSTOFF FAB

Designated contracting state (EPC)

AT DE FR SE

DOCDB simple family (publication)

EP 0138484 A2 19850424; EP 0138484 A3 19860702; BR 8405320 A 19850903; CA 1240456 A 19880816; FI 844071 A0 19841016; FI 844071 L 19850421; JP S60146090 A 19850801; NO 844062 L 19850422

DOCDB simple family (application)

EP 84306656 A 19840928; BR 8405320 A 19841019; CA 462872 A 19840911; FI 844071 A 19841016; JP 22029984 A 19841019; NO 844062 A 19841010