X-Ray Diffraction and Infra Red Spectroscopy:
Wet grinding results in the least damage to the samples'
crystal structure which is crucial for XRD and IR. It also makes
for easier total sample recovery, eliminates the manual element and
vessel cleaning, and reduces sample oxidation and cross
contamination. It is superior to dry grinding in that it yields
much smaller particles, narrower particle size distributions and
gives more uniform phase distributions.
X-Ray Diffraction:
Dry grinding can be used to induce microstrains in the
crystal lattice for the determination of ultrastructural damage by
XRD line broadening measurements. Sample weight, grinding element
type and grinding time are the only variables which need to be
specified when describing the amout of induced lattice
deformation.:
Atomic Absorption
Analysis:
In the case of samples which are difficult to dissolve,
grinding with the mill is found to facilitate subsequent acid
digestion or alkali fusion greatly.
Principle of Operation
A 125 ml polypropylene jar containing 48 grinding pellets
in ordered array is gyrated around a horizontal axis.
Grinding may be carried out wet or dry.
It is absolutely necessary to maintain
the ordered array of 6 layers or 8 pellets in the jar.
During grinding each pellet moves with
respect to its neighbours so that both the ends and the sides of
the pellets contribute to the reduction of the sample. The powder
is continuously circulated around the grinding pellets and is
rapidly ground.
The mill must be secured to a
substantial, rigid bench to ensure that neither the bench nor the
mill move during operation. All the vibrational energy available
should be directed to the grinding jar and holder and not to any
other structure.
Ideally, vibration of the mill unit
itself should be barely detectable.
On wet grinding runs the mill is
operated for periods ranging from 2 to 30 minutes, depending on the
fineness of the product required and the fineness, volume and
grinding resistance of the starting sample. Changes in grinding
time affect the particles size distribution of the product.
