Retsch BB 200 - Manual (Page 15)

04/05/2012 Retsch GmbH
15
Working instructions
Target group: Laboratory technicians
General
The BB 200 is a rugged, floor-mounted unit which is used
primarily for preliminary grinding in preparation for final size
reduction.
Its continuous operating concept also makes the BB 200
suitable for integration into fully automatic and semi-automatic
processing lines.
The performance data, throughput rates and ultimate fineness
which can be reached will depend on the breaking properties
and hardness of the product and on the gap width which is
selected.
Grain size of feedstock product
The maximum grain size is determined by the size of the fill
hopper opening and in the BB 200 is a maximum of 90 mm.
Properties of the product being ground
Every hard and brittle product, exhibiting a hardness of greater
than 3 on the Mohs scale, can as a rule be reduced with the BB
200.
Wet and oily product and that with a hardness index below 3
(Mohs scale) tend to be compressed and clump in the grinding
chamber, this being due to the pressure exerted by the breaker
jaws. It is for this reason that pre-grinding such material is
hardly possible.
Fill volume
If the grinding chamber W is filled more than 2/3=800ml full,
then the guide plates of the fill hopper could be damaged and the
moving breaker would force the product into the crusher
housing, behind the breaker arm. Fig. 6
The fill level will also influence the proportion of fine material in
the product or specimen after preliminary grinding; the fuller the
grinding chamber, the greater the share of fines.
Fig. 6
If the grinding chamber W is filled more than 2/3=800ml full,
then the fill hopper guide plates could be damaged; the moving
breaker arm would force product into the crusher housing,
behind the breaker arm.