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In this video Paul Andersen explains how mining is used to extract valuable minerals from the Earth’s crust. Surface and subsurface mining are used to extract ore which is then processed. A discussion of ecosystem impacts and legislation is also included.
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Transcript Provided by YouTube:
00:03
Hi. It’s Mr. Andersen and this is environmental sciences video 19. It is on mining. In 1848
00:10
at Sutter’s Mill in California James Marshall discovered some gold. This kicked off the
00:14
gold rush. Over 300,000 people came by land and by sea to California to strike it rich.
00:20
A few did, most of them did not. The people who did make money were the merchants who
00:25
were selling mining equipment. But what is mining? It is extracting valuable minerals
00:30
from the earth, locked away in the earth and locked within ore within the earth. Now we
00:35
need minerals. My computer is made of minerals, my glasses, my ring is made of minerals. We
00:39
need minerals. The problem is that they are formed naturally and they are distributed
00:44
unevenly. And so we are going to have different reserves in different parts of our planet.
00:49
Once we discover those reserves however, mining allows us to pull it out. Once it is gone
00:53
it is gone. These are nonrenewable resources. It is not like crops where you can plant them.
00:58
Once they are gone they are gone. What do we do once we have pulled the ore out. We
01:01
process it and what is left over are called tailings. Now there are a lot of different
01:05
types of mines. We have what are called surface and subsurface mines. Surface mines could
01:10
be things like strip mining, open pit mining. We have mountain top mining and placer mining.
01:16
Subsurface is where we actually dig down below the surface. Now we have had legislation that
01:20
has been put forward to encourage mining. The big one was in 1872. That was the general
01:25
mining act which encouraged mining on federal lands and offered protection to miners. They
01:30
could stake a claim. Now there are impacts of mining of course. We have contamination
01:35
of the air, the soil, the water. It is a decrease in biodiversity and also it can also be dangerous
01:41
to humans who are doing the mining. A hundred years ago being a coal miner was incredibly
01:45
dangerous. You could develop what is called black lung. And so since then we have put
01:48
forward more legislation. In 1977 is the surface mining control and reclamation act, also known
01:54
as SMCRA. It is a way to regulate coal mining but also reclaim some of these old mines.
02:00
And so what do we need? We need minerals, valuable minerals. That could be in the form
02:04
of fuel, like coal. We can have metals. And then we can also have non metals, like gravel
02:10
for example. How did these minerals get there? They are formed through this rock cycle. And
02:15
so for example as igneous rock is cooled you are going to have minerals deposited within
02:19
the rock. They can also come out of solution. But the key point is that it is somewhat random
02:25
on our planet where those minerals are found. This shows you the uneven distribution of
02:29
those valuable minerals. So for example we might be able to find gold. But a lot of those
02:34
minerals are owned privately and we do not even where they are. The key point is that
02:39
they are nonrenewable. This is Hubbert’s peak theory, and so if you look at for example
02:44
oil extracted in Texas, once they discovered oil in Texas, the amount increased and then
02:50
it dropped off. If we look at other parts of the US it increased and then it dropped
02:55
off. Or Norway for example. It increased and then it dropped off. Once we discover minerals
03:00
in an area we are going to deplete those minerals in an area. And so everything is going to
03:04
have a peak. We will have peak coal, peak oil, peak gold. It is all eventually going
03:09
to run away. And so how do we get the ores out? How do we get the minerals out? Imagine
03:13
this is a mountain that I have kind of sliced in half. And you can see some of the valuable
03:17
ore inside it. So how do we get to it? We we could do what is called a surface mine.
03:22
So that is what they were doing during a lot of that gold rush. You have these big troughs.
03:25
We have a placer mine where we dig the ore out and then we use water to rinse it off.
03:30
And then we have the tailings that are left at the end. We could do mountain top mining
03:34
where we literally remove the top of a mountain. We do do strip mining. This is really common
03:38
with coal. So we are going to build strip after strip after strip. And then we are going
03:42
to extract that ore. We are left with a lot of these tailings. We could even get to ore
03:47
that is really deep. So this could be a giant copper mine for example. Open pit, we dig
03:51
down from the top down to the bottom. Some of these are kilometers across at the top.
03:56
Again we have that same problem, what do we do with all of the tailings when we are done?
03:59
Or we could do a subsurface mine where we sink a shaft and then we are going to dig
04:03
out those ores as well. Once we have them then we have to process them. We have to grind
04:07
up that rock. And lots of times you grind it over and over and over again. So if we
04:12
are looking at for example a copper mine, now I have these really small ore and so I
04:18
have to extract the minerals. So I could do that with chemicals and also they will use
04:22
bubbles. So this is froth filtration where we will get the minerals deposited on the
04:26
surface of these bubbles. We extract them that way. And then we use smelting which is
04:30
heating them up. We get different densities and so we can pour off a lot of the, what
04:35
is called slag, the metals that we do not really need. But when we are done we are left
04:40
with what are called these tailings. And it is hard to get rid of those. This is red mud.
04:45
It comes from the processing that gives you aluminum. And so legislation has been put
04:50
forward to increase the amount of mining in 1872. The General Mining Act allowed miners
04:55
to mine on public lands. And it also allowed them to stake a claim. So you get 160 acres.
05:00
And so you do not have to worry about somebody else grabbing the ore. You can build up your
05:04
mining equipment and develop that. Of course there have been impacts over the last 100
05:09
years. You are removing the soil. You are removing a lot of that biodiversity. We get
05:14
some of the minerals moving into the air. A lot of it gets leached into the soil and
05:19
it is really dangerous for humans as well. And so in 1977 more legislation was put forward.
05:25
SMCRA, Surface Mining Control and Reclamation Act. It instituted the office of surface mining.
05:30
This kind of falls to the level of the states and so they are regulating coal mining. But
05:35
also it allows for reclamation of lands. And so this coal mine is actually in Europe. You
05:41
can see what it looked like years later. So we removed the soil and then we are putting
05:45
all of that back in and hopefully we get that biodiversity again. Now this problem never
05:49
goes away. We have thousands of abandoned mines in the US. You maybe heard about this
05:53
one in 2015, the Gold King Mine in southwest Colorado. It was a candidate for a superfund
05:58
site. EPA was monitoring it, but you had a rupture of the dam and we have all of these
06:03
chemicals spilling into the river that moved through Colorado and New Mexico. And so it
06:08
is a problem that we will have to deal with into the future. So did you learn the following.
06:12
Could you pause the video at this point and fill in all the blanks? I will try to. Again
06:15
what we are looking for are valuable minerals. And so the reserves are going to be here they
06:20
are found. We eventually create what are called tailings. Surface mining could be strip mining.
06:25
We also have open pit mining. In 1977 we had SMCRA put forward as a way to govern coal
06:32
mining and increase reclamation. So that is mining. And I hope that was helpful.
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This post was previously published on YouTube.
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