Butter, but no jam
November 1st 2008 When Sanitarium Health Foods switched from whole
to broken nuts for its peanut butter, its conveyor
system couldn't cope. A flexible screw provided a
free-flowing solution
To reduce costs while retaining
product integrity, Australia-based
Sanitarium Health Foods changed
from whole, cooked peanut stock to diced,
broken nuts for its peanut butter.
Nuts used to be emptied into a bin and
conveyed to a porcelain peanut mill for
grinding and blending.
However, plant engineering
manager Carl Caldwell-
Cook, says that the rigidauger
conveyor system
turned broken nut stock into
peanut butter while being
augered to the mill.
Replacing the conveyor
with a pneumatic or a
gravity feed system was
considered too complex
and to lack the necessary
control to prevent frequent
blockages.
Sanitarium uses flexible
screw conveyors in its seven production
sites and asked the manufacturer, Flexicon
Corporation (Australia) to design a
conveyor to address the problems.
In the new process, diced and broken
peanuts are emptied from bulk bags into
an 80L hopper from which a 3.25m long,
90mm diameter flexible screw conveyor
transports stock, upwards through 45°, to a
height of 3.45m above the floor. The
material gravity feeds through a discharge
adapter and downspout into the mill.
Conveying rate is 2.46m3/h.
The peanut stock has a bulk density of
480kg/m3, medium oil content and an
angle of repose of 60°. As such it is nonfree-
flowing and prone to packing, caking,
bridging and cavitation in a conventional
flexible screw conveyor and hopper.
Sanitarium uses Flexicon's Bev-Con
flexible screw for materials that have these
characteristics. The screw imparts high
directional forces and minimal radial forces
while reducing the residence time of
material in the conveyor, eliminating or
minimising product degradation.
The enclosed system also maintains
product moisture and temperature levels
and prevents contamination of material and
plant environment. The conveyor's motor
drive is coupled to the upper end of the
flexible screw above the point at which
material is discharged, so material does
not come in contact with seals or bearings.
The conveying unit consists of hopper
and flexible screw conveyor on a castermounted
frame to roll between the mill and
the cleaning area during product changeovers.
To evacuate residual material and
flush the internals the operator simply
removes a clean-out cap on the bottom of
the tube and reverses screw rotation. The
screw is removed for sanitising and
inspection. More articles from Flexicon (Europe) Limited: | 
