REFINING

93

fibre clusters or particles of pulp or paper that have in some way escaped the
action of the roll and plate, or have been packed into knots or lumps by the
violence of the beating. The roll is raised so as to be just clear of the plate, and
the beaterman uses the stirring-stick freely to turn up the stuff in those portions
of the trough that experience has shown to have a sluggish circulation. The
clearing proceeds until a sample of stuff examined in a hand-bowl shows no
lumps or knots or paper 'bits'. This may take from 15 minutes to i hour,
according to the fibres or stock being treated and how it was prepared previous

[Masson, Scott and Co. Ltd.
FIG. 30.—MASCOT REFINER WITH TOP HALF OF CASING REMOVED, SHOWING CONE
to beating. Broke filled into the beater without preliminary treatment is very
difficult to clear; in fact, sooner or later uncleared bits, notwithstanding every
precaution, will get to the machine chests and spoil the paper.
A lump of pulp or paper may lodge about the plate or backfall or stick
about the bottom of the beater, and be flushed down to the chests when the
beater is emptied. This danger, and the time and power required for clearing,
brought the 'refiner* into being.
The refiner (Figs. 30 and 31) is a machine expressly designed for clearing
beaten stock, and its proper woddng position is exactly the same as the beater
roll 'clearing'.
When the beating proper has proceeded far enough, the action is stopped
and the refiner takes up the work. Instead of the whole charge ckcubtmg
round the beater, for the purpose of treating what is relatively a very small