Mining


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

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