Here are some notes I took from the book "The Silica Sands of Ottawa". Hopefully this will give you a better understanding of how the sand is processed.
Processing
Ottawa Silica has no need for mechanical crushers. Each dynamite blast disintegrates the quarry’s
sandstone into free-flowing banks of silica composed of thousands of tons of separate
grains, just as the sand used to be, in its original state. Any few remaining boulders are broken up by
secondary blasting.
After the initial blasting of the quarry face, jets of
water under pressure stab into the banks of sand. This does three things: it breaks up the few
consolidated chunks of rock not completely disintegrated by the explosion, it
gives the sand the first of many washings, and it forces the sand into a sump
pit where it gets another cleansing.
From here, powerful rubber-lined rotary pumps pipeline
the sand to the main pumping station at the base of the refinery. Here the sand is washed again. In addition to the primary washings, the sand
has been scoured and polished in the pumps and pipelines. The sand is then moved into a large main
washing plant. A second washing is
administered as the sand is discharged into a sump and is pumped into great
draining bins. Here is where the final
washing takes place. The sand is then
left to drain.
The sand is then conveyed from the drain bins to steam
coil dryers by an overhead crane with a clam-shell bucket. The steam and vapors from the drying sand
pass off through the spaces between the pipes and baffles of the dryers and are
vented out. The sand works its way
between the pipes, dropping below onto a continuous conveyor belt. It is transported to the end of the building
and elevated up and conveyed to the top of the refinery to the distribution
screens.
Ottawa Silica Sand is not ground to size for the hundreds
of uses to which it is put. It is
screened to size, thus preserving the quality of the naturally rounded grains. The grains are screened and graded by
electrically vibrated screens with various sized meshes. The vibrating machines comprise most of the
mechanical equipment in the refinery. It
is elaborate, expensive equipment. Each
grain vibrates along the screen until it finds its particular mesh, and drops
through into bins below. Using this
method a greater variety of grades is achieved and with flawless accuracy.
In summary, sand is washed, re-washed, scoured, polished,
screened and then vacuumed. The sand is then shipped via rail using 2 and 3-bay covered hoppers.
Ground Silica Mill
No grinding is performed to effect sizing of grains. Grinding is only done in the manufacturer of
powdered silica. It is ground to the
fineness of confectionery sugar.
Originally, the sand was ground with imported beach
pebble from Danish and French coastal beaches.
Today, the grinding mill uses high-density aluminum-oxide balls to the
grind the sand. Although they are much
more expensive than the imported pebbles, the new aluminum medium lasts longer,
and does an even better job at grinding.
The powder product is stored in bins and bagged for
market.
Some Uses of
Silica Sand
·
Glass
·
Tableware
·
Sand-formed-and polished silver
·
Wall and ceiling plaster
·
Composition floors
·
Hand-washing products
·
Concrete
·
The safety in Safety Matches
·
Oil well fracturing
·
Furnace lining
·
Composition siding
·
Silicate of soda
·
Filter sand
·
Concrete improvements
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