Appeal No. 2001-0065
Application 09/048,289
1. A method of producing chemical pulp, comprising the steps of:
(a) cooking comminuted cellulosic fibrous material to produce brown
stock having shives;
(b) washing the brown stock to produce chemical pulp at a
consistency of between about 6-18%;
(c) oxygen delignifying the chemical pulp at a consistency of between
about 6-18%;
(d) screening the pulp from step (c) to produce at least an accept
fraction and a shive-containing reject fraction;
steps (a) – (d) being practiced in a main fiber line; and then after step
(d):
(e) further treating the accept fraction, and (f) directly transporting the
shive-containing reject fraction back to the main fiber line before step
(c).
18. A chemical pulp producing fiber line system, comprising:
a fiber line comprising in sequence: a digester for cooking cellulosic fibrous
material to produce brown stock; a first washer for washing the brown stock from
said digester; at least one oxygen delignification stage, and a screening stage for
screening chemical pulp from said oxygen delignification stage to produce an
accepts fraction and a shive-containing rejects fraction; and
means for directly transporting the shive-containing rejects fraction to said fiber
line before a said oxygen delignification stage.
21. A method of producing chemical pulp comprising the steps of:
(a) cooking comminuted cellulosic fibrous material to produce brown stock;
(b) washing the brown stock to produce chemical pulp; and
(c) oxygen delignifying the chemical pulp at a consistency of between about 6 –
18%, and to allow the shives to become impregnated by alkaline liquid to
enhance separation of fibers; and wherein oxygen delignification is practiced
utilizing at least first and second distinct oxygen delignification stages each
comprising an upflow vessel, and at least one of the vessels including a multiple
feeding device; and
2
Page: Previous 1 2 3 4 5 6 7 8 9 10 11 12 13 14 15 Next
Last modified: November 3, 2007