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Fish meal with high
protein content and low in minerals is in demand for feeding juveniles
in aquaculture. Digestible proteins are contained in the soft tissue
of the raw material; the minerals come from the bones. All fish meal plants
can be equipped to separate the fine fraction of the dried product from the
coarse mainstream––the bones––before it is milled,
known as Enhancement of the product. The separated fraction
can contain up to and over 80% digestible proteins and, since
it is comparatively small, the reduction in the protein content of the very
much larger volume of standard product is negligible.
(picture above) are used for controlled sifting of powdered and grainy materials,
such as wheat flour, rye flour, fish meal, blood meal, powdered milk, maize
powder, salt, sugar, chalk and other products of similar characteristics.
The mainstream is fed through a hopper (top, left) and brought into the sieve
by a screw feeder; there it is flung against the screens, where fine dust
separates and the coarser particles travel along to the outlet (right, bottom).
Turbo-sieves are equipped for self-cleaning and convenient replacement of
screens with different mesh size.
Another way of doing this––the
do-it-yourself way––is to make a section in the bottom
of the mill conveyor replaceable (picture above). Sections with different
perforations can be inserted to suit demands from the markets and/or
different raw materials, including a solid section if no
enhancement is desired.