Open-pit mining is another kind of
mining. Mining companies choose this way to get rocks and
minerals out of the ground because it is the easiest and
cheapest way to do it. Open-pit mining would only be used if
the rocks or minerals were close to the surface of the land or
if a normal tunnel-type of mine wouldn’t be possible.
At first, a
geologist examines and tests the land to
be mined. He will also check the site for what it will do to
the environment. Even before they start to mine it, the scientists know the value of the
rock/minerals below the surface and how much it will cost to dig
them up. Mining companies make plans to get as much ‘yield’ as
they can for their money. The plans and the amount of money
it will cost to mine the area will change over the years because
prices of rock and minerals change.
Once the plan is decided, the top layers of the land are
removed. After that, layer after layer is taken away until the
rock or mineral is visible. This is taken out, processed when
it needs it, and sold. Taking away layer after layer of land
creates a gigantic, open hole [or pit] that keeps getting deeper
and deeper until there is nothing left to bring out. Explosives
[like dynamite] are used when the miners want to get large
blocks of materials out of the earth. The picture above
shows how an open pit looks.
Most of the time, when the mining company is done with it,
the pit is used as a landfill. A landfill is used as a dump to
get rid of our garbage. When it is filled with garbage, it is
covered over with layers of dirt. After the garbage rots a long
time, the land can be used again.
Materials that are
usually mined using the open-pit method are:
Equipment that is used to do
open pit mining: