This roller type powder press was installed in the Swiss black powder plant in
1978, replacing the traditional vertical plate powder press.
This roller (Laminoir) type powder press is unique to the Swiss bp plant. The
only such powder press in operation.
Figure 26 shows the feed end of the powder press.
Broken down mill cake is fed onto the slowly moving rubber belt in a specified
thickness. The powder then passes under the roller. The roller operating at up to 30 metric
tons of pressure.
Figure 27 shows the pressed powder end of the press. After passing
beneath the roller the powder cake will break off and drop into the collection box.
The cake produced by the powder press ranges in thickness from I cm.
to 0.5 cm. depending on the type of powder being pressed.
Powder from the wheel mill is low in density and lacks the required degree of
cohesiveness required in a propellant powder. During powder pressing the volume of the
powder is reduced by about 35 to 40% of its original volume as it comes from the wheel
mill. The pressing operations both compacts and consolidates the powder. This imparts a
high degree of mechanical strength in the pressed powder.
The press densification and consolidation of the powder does not require that the
powder be held under great pressure for any length of time, as would be seen in the
typical plate press. Imparting mechanical strength in the powder comes about after the
water has begun to evaporate from the pressed powder cake. As the press cake is exposed
to air there will be a slight loss of moisture and a bonding within the mass that provides
the desired degree of mechanical strength to the powder.