Appeal No. 1999-0400
Application No. 08/316,938
may conveniently be performed by passing the surface
of a blade across powder on the surface of the sieve.
The function of the rolling step in the process
is to strengthen the agglomerates of particles formed
in the extrusion step, and to mould them into a
spherical shape. The rolling may conveniently be
effected by allowing the agglomerates to tumble in a
rotating vessel, preferably a cylindrical vessel.
The screening step removes over and undersized
pellets. It is conveniently performed using two
sieves with apertures defining the upper and lower
desired pellet diameters [page 4, lines 15 through
25].
Edwards goes on to detail a specific embodiment of this
process in Example 5:
Form X was micronised to produce a powder
consisting of at least 98% by weight of particles
having a diameter of less than 10 microns.
30g of the powder was then placed in one heap on
a brass sieve having an aperture size between 210 and
500 microns. The powder was then extruded through
the apertures of the sieve using a stainless steel
pallette knife. The extrudate thus formed was then
placed into a screw topped glass jar.
The glass jar was then placed on to a set of
rollers, which were rotated at 100rpm for between 8
and 20 minutes. The soft pellets thus formed were
then sieved through an 850 micron sieve and then a
150 micron sieve, the fraction retained on the 150
micron sieve being the required product.
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