Placer deposits are the coastal sands, which are located along the
shores of oceans, seas and rivers. The size of mineral particles is 0.07-0.2 mm
(to 1 mm). Placers are occupied from hundreds of meters to tens of kilometers
along the coast. The width of the placers is tens of meters (sometimes hundreds
of meters). Seam Thickness is 2 meters (sometimes up to 10 meters).
Placer deposits are a traditional source of the production of zirconium,
rare earth, titanium, tantalum, niobium, tin metals. Mining and processing of
placer deposits are very developed throughout the world
Today, due to the rapid development of technology, the extraction of
marine placers is possible. There are special marine dredges.
This is a very important point, because stocks of marine alluvial
deposits are very large.
In my opinion, the placer deposits can be considered as of
the most promising feedstock for obtaining RARE EARTH, TITANIUM, TANTALUM, NIOBIUM,
ZIRCONIUM AND TIN MINERALS.
Placers are the complex raw
materials and they contain:
Rare earth
minerals (mainly monazite, xenotime and sometimes euxenite)
Titanium
minerals (ilmenite, rutile and leucoxene)
Zirconium
minerals (zircon)
Tin minerals
(cassiterite)
Tantalum
and niobium minerals (columbite, tantalite and euxenite).
Corundum
Garnet
Kyanite
Quarz
(ganga)
To extract minerals from placers one can use
environmentally friendly and cheaper technologies. Since the placers are small
particles, there is no need to apply crushing and grinding.
Current and future processing schemes of placer
minerals are included usually several ways of gravity separation of minerals to
produce a collective concentrate (schlich, heavy concentrate). The tails of
placer minerals don’t accumulate. The tails return to the ocean in a secure
form (in the same form as the original raw material). Next may be used a
combination of advanced methods of wet and dry separation of minerals. The
schemes of ore processing may be different by sequence of operations depending
on the mineral composition of placer. I would not recommended the use of
flotation for the separation of placers due to the formation of harmful
tailings. Today, there are environmentally friendly methods of mineral
separation.
The
processing of placer deposits has many advantages:
1.
Processing of placer deposits
is produced by environmentally friendly technology without the use of any
chemicals. Virtually no negative impacts on the flora and fauna of the ocean
and coastal areas.
2.
Processing of placer deposits
decreases the radiation background at the shores of seas and oceans. The
ecological situation is improving becourse radioactive minerals are removed
from the beaches. Beaches become a beautiful light color.
4.
Perhaps the complex use of
raw materials and the obtaining of several concentrates, which increases
profit.
5.
The use of cheap technology.
6.
Low cost of search and
exploration of placer deposits. One deposit can be used for long time. Ocean
continuously feeds new portions of raw materials without a limit.
7.
There are no the costs for
the construction of the quarry or mine.
8.
Low construction costs for
the processing plant. One floating plant – the marine dredge can be used for 50
years and more at the numerous placer deposits.
9.
There are no the costs of
crushing and grinding.
10. There are no the waste rock dumps, tailings
containing hazardous and radioactive waste. There are no the costs for it.
11.
There are no the costs of
restoring the site.
12.
Fresh water is not used.
There are no the costs of preparation and purification of fresh water.
Separation is made directly in seawater. Not any chemicals or minerals pollute
the seawater.
Development of marine placers are very
promising direction.
It is solution of tomorrow day.
However each placer deposit has its
own individual characteristics.
Each ore must have its own individual
technology.
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