CHAPTER

REPULPING 'BROKE-EFFECT OF ADDING BROKE TO THE
FURNISH-BROKE AND WASTE
WASTE paper, properly treated, is an important and valuable raw material
for the paper-maker, yet it would seem, from the inadequate space and appli-
ances for dealing with the disintegration of broke which are found in most
mills, that this department was seldom planned out at the beginning, but was
added when the necessity was realised. Yet it is in this department that a great
deal of money may be lost or saved. There are several methods of dealing
with broke or waste paper so that it may be again used in the furnish. Wet
doctor broke from press rolls may be carried to the beaters and packed in with
the next charge. Broke that has been dried but not tub-sized is sometimes
filled in and cleared with the other items of the furnish.
This, however, is a risky process, as even with the greatest skill and care
it is often the case that uncleared bits get into the chests.
The method employed must be one that is best adapted for the particular
qualities made, and will depend on whether waste paper bought from outside
die mill is used. So we find that nearly all mills have their own methods, of
which the following are typical:
1. Soaking in tanks.
2. Boiling or scalding (either in stationary or revolving boilers).
3. Breaking in potchers with hot water, followed by steeping in draining
tanks.
4. Boiling, followed by breaking, in edge runners, kneaders or pulpers.
.5. Breaking in pulping engines with steam or hot water, without pre-
liminary treatment.
From the above it will be seen that there are two essential requirements:
(a) the soaking in water (generally hot) and (&) the mechanical action of de-
fibring. To get good results these two must be combined in the process:
(a) alone takes too long a time and too much space for tanks, with imperfectly
soaked bits left to be dealt with by the beaters; (b) requires too much power
without (a) and is useless for reducing hard-sized papers.
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