Allana Potash fka AAA

[AAA-FTW]

Another Comparison Surface VS Underground Mining

One of the major advantages AAA and the other potash plays in Ethiopia have over ALL OTHER Potash miners in the world is the potential to be the only open pit potash mines in the world.

Because we are going to be somewhat the pioneers at this, I've been researching this a bit more to see if there were any "issues" that may impact the likelihood that AAA will be able to succeed.

I found this technical article comparing SURFACE VS. UNDERGROUND METHODS

Some of the highlights include:

The development of a large underground mine can take from
five to ten years. The interest cost during the construction time
will thus be high and can account for up to 30 to 40% of the
capital requirement before mining can start.
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Many surface mines operate 24 hr/day and almost 365 days/
yr. The high capital requirements for purchase of open pit equipment
make it important to use as many hours per year as possible
so the number of machines can be reduced. In the case of a
machinery breakdown, it is often easy to move the vehicle and
replace it with a spare, so that ore production can resume.

Underground mines, on the other hand, often must limit their daily,
weekly, and yearly operating times because of the need for ventilation
and maintenance. In the case of underground coal mines,
tradition and union attitudes have so far prevented work crews
from being rotated into weekend time slots. This makes the
number of mines greater than what it could be with a higher
equipment time utilization and the capital requirement higher
per ton of capacity.
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In a surface mine, a large part of the operating costs is
variable. If a surface mine operator must decrease production,
it is often possible to sell the mining equipment, because there is
a large market for such equipment that is also used by other
industries.

Underground mining requires more mine-specific equipment.
In addition, large amounts of money are often invested in
shafts and haulage systems. It is, therefore, more likely that an
underground mine will keep producing as long as the revenues
cover the variable operating costs, even though the operation is
not profitable on an overall cost basis.
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In a surface mine, it is normally possible to recover almost
all the mineral or coal one wants to mine. As a general rule, surface
mining allows extraction of a larger part of a deposit than if
underground methods are used.

The recovery underground is usually lower and depends upon the mining method
used.
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Published data indicates that most surface operations require
5 to 10 kWh energy equivalents/ton of rock handled. Most of
this is diesel fuel, although the use of electric power has increased
in recent years because of trolley-assist trucks and in-pit crushing
and conveying.

Underground mining normally requires an average
of 15 to 30 kWh of energy equivalent/ton, with up to 50
kWh in smaller cut and fill operations. A large part of this is
electricity. During recent years, electric trucks and load-hauldump
(LHD) equipment have been developed.
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Only in very cold or hot climates do miners find it better to work underground than in a surface
mine.