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.