17
Alumina Ceramic
is harder than tungsten carbide, but is comparatively
lightweight. It grinds fairly slowly with low contamination
levels and is subject to fracture. Major elements: Al. Minor
elements: Si, Mg, and Ca.
Size
There are four sizes of ShatterBox grinding container: small, medium, large, and
extra-large. To pick the correct size it is necessary to know the minimum amount
of sample you have to grind, its approximate density, and the fineness of grind
desired, as each may affect your final choice. The typical sample capacities of each
container type are given below in grams, assuming a sample of the density of quartz
sand, rock, etc. (approx. 2 to 3-1/2) and the requirement to pulverize the sample
to around 325 mesh (44 microns). The sample capacity volume RANGE, which is
much broader, is given in ml. If you are unsure which ShatterBox grinding container
to select, consult our product specialists. You can also send your samples in for
evaluation and test grinding.
Small
:
8507 Small Hardened Steel and 8508 Small Tungsten Carbide
grinding containers. Each has a puck-shaped grinding element.
Typical sample capacity 8-15 grams, sample volume range 5-20 ml.
Requires 8507R Rack to operate one 8507/8508 or three
simultaneously.
Medium
:
8505 Alumina Ceramic and 8506 Zirconia Ceramic grinding
containers. Each has a puck-shaped grinding element. Typical
sample capacity 20-40 grams, sample volume range 15-40 ml.
Large
:
8501 Hardened Steel and 8504 Tungsten Carbide grinding
containers. Each has a puck and ring. Typical sample capacity 25-
75 grams, sample volume range 20-50 ml.
Extra Large
: 8521 Large Hardened Steel grinding container, with puck and ring.
Typical sample capacity 50-150 grams, sample volume range 30 -
100 ml.
The sample volume ranges given above are estimates, not absolute limits. The
upward limit on the weight/volume of a given sample for a given grinding container
is really determined by the point where the mill stops grinding the sample
satisfactorily. This limit can vary with the type of the sample and its particle size.
The lower limit on the size of the sample is usually reached when the sample
becomes highly contaminated and is hard to recover. (If very little sample is ground
there is a lot of direct contact between the grinding element or elements and the
container, and under these conditions the tungsten carbide and ceramic grinding
containers are more likely to become chipped.) Avoid grinding large chunks of
sample, as these can either jam the grinding container or damage it; even if they
grind satisfactorily, they will probably not grind consistently. We recommend
reducing the feed size to at least 1/4" for the tungsten carbide and steel grinding
containers, and to 1/8" for the alumina and zirconia ceramic grinding containers.
When developing a procedure for your combination of 8550 ShatterBox and
grinding container, try a sample size near the middle of the given range(s). Grind
for two minutes in steel or tungsten carbide, or four minutes in alumina or zirconia.
If grinding is not satisfactory but the sample is not caking, try increasing the
