The Impacts of Mining: Understanding Resource Extraction and Its Environmental Effects

hi everyone welcome to this lecture on the impacts of mining for AP environmental science

and we're only looking at one learning objective today that's topic 5.9 and the enduring understanding is that when

humans use natural resources they alter natural systems which we'll see as we move forward through this

the learning objectives are twofold describe natural resource extraction through Mining and describe ecological

and economic impacts of natural resource extraction through mining so basically be able to describe mining itself and

then be able to describe the effects of mining here's the vocab if you want to pause it

and jot this down and Mining is really really really important

um most of the materials that we get that are not plant or animal and origin come from mining so of huge wealth of

materials but mining itself is the extraction of valuable geologic materials from the earth that could be

in rock or liquid or even gas form we get a lot of things from mining so fossil fuels coal oil and gas so we see

both solid liquid and gas right there um uranium oil for Plastics so most Plastics are made from oil All Metals

gems uh and rock for building clay for bricks groundwater and you can even mine some

fertilizers most notably phosphates and then salt is one of the big ones for food so we get lots and lots and lots of

different things from Mining and most of human construction and human Goods if they are not made from plant or animal

materials are coming from the ground and one way or another and it's really important to note that

all resources that we extract from the ground are non-renewable all of these are non-renewable resources now

they are finite some are renewable under geologic time um say groundwater is renewable if you

allow that ground Waters to recharge and some of them are so prevalent that it seems as though we'll never run out a

good example of that might be clay for bricks and pottery I mean there's different grades of clay and everything

but in general it'd take a very very long time for us to exhaust our resources at clay the resource all right

the the um amount of oil on the planet though is a

lot more finite than um than Clay is okay but we get all of these things from Mining and many more

and if we break mining down into two very general categories we have surface mining and subsurface mining otherwise

known as underground mining I'm going to start with surface mining as we talk about this surface mining is where the

overburden is removed to access that deposit and your deposit is whatever you want to extract the or or whatever

material it is that you want to extract okay and that material is typically near the surface so you could just remove the

overburden and the overburden is The Rock and soil above that deposit so I'll show some pictures on the next slides

um but we're just literally removing the soil the vegetation and The overlying

Rock above that deposit whatever it is set it to the side or setting it somewhere and then accessing our deposit

from the surface and we can break surface mine into two into three large categories although

there are a few others that exist strip mining is the removal of overburden and Lawn strips to access the deposit

beneath and then the next strip that you use the overburden fills the previous strip

okay so you kind of go in this um in this manner where you dig out one strip access everything dig out the next strip

the overburden from that one goes and fills this one you probably have a bunch of overburdened over here from your

original strip and then another one

overburden is used to fill that Etc open pit mining is where you just carve a huge pit or a crater into the Earth

and mountaintop removal mining is where you remove the top of a mountain to access the

material inside of that mountain essentially what you do is Blast Off The Ridges and the peaks of that mountain

and that overburden is dumped off the sides of the mountains and to nearby valleys this primarily occurs for coal

extraction and the Appalachian Mountains and it is one of the most ecologically devastating types of mining

all right so this is a example of a strip mine this is the Bear Run mine in Indiana it is a coal mine and

essentially what they're going to do they're accessing the coal which is this darker material down here

and these lawn strips so they dug out one strip and they dumped all their overburden

right there on the ground next to it and then when they go and dump out I dig out this next strip which they probably

won't because that looks like private land like it looks like Farmland but whatever

they'll dump that overburden into the previous strip and they just do it in these lawn strips and you can see how

they um how their Machinery accesses it with these ramps that they leave and everything else

okay so that's strip mining and again you can see that it's a surface mine because it is at the surface it's at the

ground surface and you're not digging um tunnels and channels and shafts Underground

this is an example of an open pit mine this is the Twin Creeks gold mine in Nevada

um this is a very very very large pit you can see the size of these very large um

bulldozers or tractors that they use to remove material this looks like a portal potty for scale so you probably are very

familiar with those for scale so this is a very large very large pit and then an example of mountaintop

removal so let's just say that this mountain in the foreground looked like this mountain and the background and

essentially what they did is they located their coal seam and they started removing the material

above that so they're just blasting off all of this overburden and Blasting it down the sides of the mountain one way

or the or the other and then we have underground mining also called subsurface mining this is what

you probably think of as miners doing they're digging tunnels they're digging shafts into that into the Earth and

extracting deposits underground there's a lot of different types that exist but we're not really going to get into those

although I do want to show these pictures um this is from a salt mine in Poland I'm not even going to try to

pronounce um what this salt mine is called this is an underground mine so they're mining

salt out of here and as I was doing my research I came across some of these pictures and they're it's just like this

amazing City carved out of salt and rock underground it's really really kind of cool so

um it's a tourist attraction now I don't think that they actively mine the salt out of it but just thought I'd share

these pictures and like I said there are other types of mining that are less common so for

example we could be talking about groundwater mining which will which we have and will continue to talk about uh

several times so this is on the example in the bottom left where you have a house and a well and that well is

extracting groundwater you could be talking about the insutu leaching of uranium which they do and to

recover uranium for both weapons and more commonly for power plants we could be talking about oil drilling natural

gas extraction but we'll talk about those on other days when we talk about oil and natural gas in our energy unit

okay again and most of these materials um that we mine are finite resources now some of them will be replenished over

geologic time but we're going to treat all resources that we mine as finite because

um even if they're replenished over geologic time scales that's not on human time scales and for something to be

sustainably used it has to be sustainably used over a human time scale right it has to be replenished over a

human time scale and we have already gone through many of the readily accessible deposits for

pretty much every um every ore or every material that we've that we want around the planet

because those are the easiest to get those are the lowest hanging fruits right the stuff that is closer to the

surface the stuff that's um maybe in less dense Rock the stuff that is of higher quality or higher concentration

we've already gone through much of that for the different um the different materials that we want

to access we are moving towards and have been for a while deposits are more difficult to

access meaning that there's probably more overburden there's more cost and accessing those there's more fuel use

for the Machinery all of that stuff and then also lower quality deposits which means that there's more impurities

which means that we have to refine those impurities out which leads to a greater environmental cost and all of

the chemicals and water and everything that is used to refine materials okay and there's a ton of different processes

all for different materials that we're not going to get into in this class so both of those are going to be lead to

increased costs that are transferred to the consumer and there's going to become a point with pretty much every material

you know give or take where extract where the cost of extracted them is going to be greater than the cost that

they can sell it for so the cost and the amount of resources used will become unprofitable and we'll go through a

couple examples of those both fossil fuels so the first one is peak oil um

scientists have been predicting when peak oil um

will be for several decades and their predictions have more or less always been wrong

um scientists in the 70s thought that it might be in the 80s or 90s we know that that isn't the case because we're still

using oil scientists in the 90s might have thought that it was in the 2010s but we keep finding new deposits and

keep finding ways to new ways to extract oils such as from tar Sands or from fracking that have extended

um our use of of petroleum but anyway peak oil is the theoretical year which will come eventually because this is a

finite resource at which the rate of petroleum extraction will reach its maximum after

that it's going to Plateau so in this diagram it looks like it's maybe

if I could draw a straight line in the 2020s okay we don't know when it is but maybe some some sometime in the near

future okay because oil is finite there's only so much oil eventually the supply is

going to run out but before it does it's going to prove economically unviable to extract because we're essentially going

to at some point maybe around like right here maybe here maybe down here it's going to cost the equivalent of one

barrel to extract one barrel so once that does once it becomes unprofitable to extract oil then oil

will no longer be extracted or at least it will for only certain uses okay

and needless to say before we hit peak oil our oil-based economy really does need to shift in a major way

another example is coal now coal we believe that Peak coal occurred in 2013. because coal extraction and coal

use has declined ever since 2013. so a little bit of history about coal Coal Mine started as subsurface mines just

before the Industrial Revolution when people realize that you can burn this black rock and heat your homes

and uh use it to smelt steel and all of that stuff and then um

the Industrial Revolution hit coal became heavily used and much of that was from surface mines sorry subsurface

mines my bad um with larger Machinery it turned into

strip mining like we saw on the Indiana slide and then mountain top removal remaining like we saw in the appellation

slide but now that we've cleared out most of the surface deposits of coal we're

moving back again to subsurface mining so what remains is a little bit more rare a little bit more less pure in

terms of it being anthracytical which we'll talk about when we get to our energy resource uh unit and it's moving

into this subsurface mining and this is causing prices to increase and they have been increasing for the

past 50 years or so now obviously this is a huge generalization um in these three stages have occurred

at different times throughout the world in different countries as they go through the demographic transition but

in general this is what we've seen all right now let's get into the second learning objective which is the

environmental impacts of mining so there is a lot of environmental impacts and we're going to talk about each one of

these individually so the first one that we're going to talk about is the disposal of both

overburden and slag now I'm talking about both of these at the same time because the the disposal

of both of these materials is very similar but the materials themselves overburden versus slag is very different

and where they come from is very different so overburden

um has to be disposed of recall that overburden is the overlying Rock

and soil and often vegetation as well that is above your deposit

and overburden is greatest in surface mining okay now you're going to have some

overburden or at least material that you have to remove if you're doing subsurface mining because you have to

dig those shafts and you're going to dispose of that stuff as well but overburden is definitely going to be

greater in surface mining okay that has to be disposed of if your mind is you know right here then and all of this

outside of that is Forest so you clear-cut a patch of forest and put in your mine

you have to have some place to put that overburden so you're going to move that overburden

onto a patch of forest and degrade that patch of forest that overburden has to be disposed of somewhere and it's too

expensive too heavy and there's too much of it to cart it away too far so typically what they do is dispose of it

right next to the mine slag is a different product slag is a byproduct left from the

refining process of raw ore when you're making Metals okay when you're refining Metals so if you've ever seen somebody

smelt iron maybe in like a history show or maybe copper you know that you get a tiny little nugget of iron or a tiny

little nugget of copper and then you get all of this other Rock that's waste that rock that's waste is your slag

usually it's dumped in the molten phase so on the top right we see a train that is carrying slag from a Foundry where

they're probably smelting well they're definitely smelting some sort of metal and as a molten liquid rock they're

disposing of this slag off of the side of this train track and they're creating these slag mountains that we sleep that

we see on all on all these other pictures okay that is

that slag is very heavy and heavy very high in heavy metals it's typically like Solid Rock that's that's um that that is

just laying there so it's very difficult for plants to grow on imagine this is like you know Lava Rock right it's it's

not but it's um it pours out and flows like lava it cools like lava and it's just like solid rock metal

um right there and nothing can really grow on that or at least most a lot of things cannot grow on it without going

through the stages of succession okay um

you may see the terms clinker or dross those are somewhat similar to slag they're different but we don't really

have to get into the the um the technical differences but they have to be disposed of as well and their

disposal is very similar and has the same environmental impacts essentially habitat loss for the most part

and then there's mine tailings mine tailings are somewhat similar but mine tailings are the waste material that's

left over after the economic material is extracted that's at the mine okay so mine tailings are going to occur at the

mine you're going to have some refining at the mine or some sorting of rock to see what rock has

valuable stuff in it what doesn't and then a little bit of refining as well depending on on what you're on what

you're mining it could be a lot of refining and you're going to refine it as much as

possible just at the mines so you have less Transportation cost to move your ore to The Foundry or the factory or

wherever it's going next okay and that's all going to create mine tailings so again these are the fraction

of rock that's left over after the economic material has been removed usually it is in an aqueous form

so we have this mixture of water sand clay rock and all the chemicals that they use to extract the economic

material or to partially refine that economic material those can be extremely toxic and these tailing ponds are often

very high in heavy metals and other pollutants those aqueous Solutions are often stored

in tailing ponds which you see up here and the top right and you notice the different colors of these tailing ponds

are due to the different chemicals that are in those okay however tailings can also be solid

so that's what we see right here that tailings pile is the solid rock that's left over

um and it's just not an aqueous solution okay so it's just stored as Solid Rock

most uh mines pre 1900 just had tailing piles and if you go

hiking up in the Colorado Rockies and you see like a very old mine shaft and you can often find the tailing pile

right next to the old mine shaft and a lot of times those old tailing piles are going to start to be covered by

vegetation but they're still very distinctive as tailing piles because it's um it's rock that's obviously been

piled up by humans rather than by a geologic process nowadays it's mostly

tailing ponds okay now this is where we don't see like this is

one of the things that we don't see as consumers there's a huge amount of waste that's generated from resource

extraction so for example one ton of copper produces 99 tons of tailings so it's only about one percent efficient

okay so imagine that you get your one ton of copper that goes to make pipes and makes

um you know a electrical wiring and all of that stuff only one percent of the rock that was

extracted from that mine actually went to make that copper wire the rest of it is left piled up somewhere or Worse an

aqueous solution somewhere that has to be jammed up and kept and uh monitored for years to come

gold is even worse um 5.3 grams of gold produces one ton of tailings so one ton of gold produces 200

000 tons of waste rock and and to give perspective a gold ring is about three to five sorry three to

ten grams of gold depend on the Carrick and I I don't know gold rings and stuff but you know

whatever um so let's just say 5.3 grams is average for that 5.3 gram gold ring that

somebody's carrying around there's a ton of tailings one ton of tailings sitting somewhere

and then we that brings us to water pollution um mining in general uses a lot of water

just vast amounts of water um just like everything else that we do it needs water

um so much of that water is going to be Laden with with various types of

pollutants those pollutants could include arsenic or heavy metals I have some examples of those heavy metals a

lot of these tailing ponds include different acids whether that's Nitric phosphoric or sulfuric acid for sulfuric

acid always think coal I have a slide about that in a little bit um

and whenever tailing piles are piled there or any other mining material is piled up leaching a runoff also occurs

and Carries pollutants away that could be as innocuous as just sediments but it could be you know heavy metal pollution

as well okay all of that Wastewater from mining has to be disposed of in some way now

there's really no great option for this one option is to just leave it in tailing ponds I'll talk about one of the

consequences or potential consequences of that on the next slide the worst case scenario is that you dump

it in the nearby River this occurs in many of the developing nations around the world especially where laws and

regulations are a little bit Lacks um also worst case scenario submarine tailing disposal this is basically where

you take your mine tailings and um and dump them into the ocean or pump them into the ocean via a pipe that's illegal

in the US and Canada but it's practiced a lot in the developing world some other options though subsurface

tailings so you basically pump your mine tailings into porous ground walk ground rock into porous Rock in the ground like

Limestone and you essentially make um like your little like a little tailing aquifer the best case scenario

would be if you have let's say that's the surface of the of the ground and you have impenetrable materials such as a

clay and then another impenetrable materials such as clay beneath that and between those two layers of clay

you have limestone you can pump your tailings into that and they will be confined by those two

layers of emporis clay or impermeable clay rather not a great solution it can contaminate

groundwater it can contaminate aquifers and ruin drinking water or irrigation water for people and crops and animals

one of the cool Solutions is remediation by bacteria algae or plants this is definitely the most sustainable option

but it only works for certain pollutants some of these pollutants can be neutralized or can be metabolized by

different organisms and we can use those different organisms to refine our tailings

all right so let's look at a local example of water pollution from um a mine tailing now I should start

this off by saying how tailing ponds are constructed nowadays and obviously there's going to be lots of variation

um in their construction or in the way that they're made um you know whether based off of what

when that mine was uh created when that when the mining activity was done and what type of mining activity it is but

in this case you can see that there is a tailings pond here that tailings pond um you can see the remnants of it right

now and you can see that the base of that is plastic or rubber that they put down so they're going to dig out a pit

line that pit so that's the ground surface they're going to line that pit with plastic or Rubber and that ground

surface is actually probably going to be on a slope because a lot of a lot of mining happens in mountains so they're

going to have to Dam it up okay so we have our dam and we have

a plastic or rubber lining so that the tailing water does not go

and leech down into the um into the soil so this water is not going to go into the soil

it will instead just stay inside of this tailing pond that's not foolproof though this Dam can

rupture and if that Dam ruptures that water will go down downhill and that's what happened with the tailing pond at

the Gold Keene mine Dam that was near Durango Colorado or still is near Durango Colorado in

2015 the EPA of all groups of people accidentally um breached the dam uh while they're

doing some cleanup activity and they released about three million gallons of tailings into the cement Creek which

eventually um or very quickly actually went into the Animas River so the cement Creek is a tributary of the Animas river

which is a tributary the San Juan which is a tributary to Colorado okay

now it turned the water from bluish green to this rust colored orange that you see on the top right and on the

bottom left with what remains in the tailing pond now the environmental impact was pretty

severe but locally in the Animas River it wasn't that severe it was actually a

little bit worse into the San Juan in the Colorado the Animas River the reason that it wasn't quite as severe is

because um some stretches that River are already virtually devoid of life like before

this breach occurred due to all of the mining activity that's occurred there over the past 150 170 180 years

um you guys probably know growing up growing up and living in Colorado at least many of you

um that Colorado is a mining State okay there um through the 1800s especially

but I mean still today a lot of Colorado economy was based around Mining and the EPA was only

created in 1970. so before that people could just dispose of their tailings anywhere and in any way for the most

part okay barring any local regulations and a lot of contamination has already occurred in the Animas River and it's

led to some Rivers being some stretches of the river being devoid of life before this accident and then

um some fish populations near Durango um sterile so they're incapable of reproducing the Animus is typically

stocked by the official Wildlife service and um and is uh um you know pretty heavily contaminated

already but this is an example of a mine Dam failing or a mine tailing Pond um Dam

failing okay finally let's just look at coal for a little bit

um Cole perhaps is the most um heavily polluting natural resource that we consume um specifically mind resource

when you mine coal you first have to purify the that that coal bearing Rock to get the coal out of it you have to

wash that coal to remove any surface impurities and anything else you have to store that coal and all that's going to

expose it to lots of water you see the water right here maybe this was just right after a rain and your pile of coal

um as it rains on coal you're typically going to be making a lot of sulfuric acid because

coal often has sulfur in it it often has sulfur content and the associated rocks often have sulfur content with the

associated rocks we're often talking about Iron II iron ii disulfide which is pyrite also called Fool's Gold so in the

presence of water the iron and the sulfur will dissociate sulfur will react with the water to create sulfuric acid

okay recall that sulfuric acid is h2so4 okay um

that sulfuric acid is uh can run off into surface waterways it can Leach down into groundwater and it will obviously

lower the pH of any of the waterways that it gets into okay

now for this part we're going to talk about coal combustion when we talk about atmospheric pollution but in general

for right now just know that coal doesn't just release carbon dioxide in the atmosphere when you burn it just

like burning everything does but you'll also release some carbon monoxide you'll release sulfur dioxide from The sulfur

you'll release nitrogen oxides often and both of those will lead to acid rain among some other effects or acid

deposition I should more appropriately say okay so acid rain or acid deposition but we'll talk about both of

those when we get to our atmospheric pollution unit um coal combustion also releases

particulate matter that includes dust lead cadmium and other heavy metals as well as arsenic which isn't technically

a heavy metal it's a transition metal anyway let's get back to all right to the

learning objectives for the Essential Knowledge as the more accessible ores are mine to depletion mining operations

are forced to access lower grades accessing these requires increased use of resources that can cause increased

waste and pollution so recall that as we have moved through all of the readily accessible

deposits we're moving to those that are less accessible those that are more difficult to obtain just due to that

nature of that of being more difficult to access it's going to use more resources oil petroleum resources most

specifically but it's also going to require more manpower and more time and create more waste in the form of

overburden or slag or tailings surface mining is the removal of large portions of soil and rock called

overburden uh recall that we have three types we have strip mining pit Mining and mountaintop removal mining

okay and then mining waste include the soil and rocks that are removed to gain access to ore and waste um so this is

the soil and rocks that are moved that is your overburden um

this is not technically correct called slag entailings that remain when the minerals have been removed from the ore

so slag is when you are processing that material in the and The Foundry or in the factory and you're getting the bits

and of waste rock off of the off of the material that you want off of the metal that you want and you're depositing that

typically in a molten form and then tailings are what's being left at the mine itself so all of the waste rock

um from the mine itself not the overburden but from the um from the mine itself and then also the aqueous

solution of all the chemicals and dissolved rock and all that stuff dissolved soil and minerals and all that

heavy metals at the mine itself mining helps to provide low-cost energy

and material necessary to make products so we're talking low-cost energy primarily fossil fuels also uranium for

nuclear energy and material necessary to make products so that first slide where we talked

about all the materials that we get from mining the mining a cool can destroy habitats contaminate groundwater and

release dust particles and methane we'll talk about the methane release later on in the school year

especially related fossil fuels but realistically it's not just the mining a coal it's the mining of really any

material that can destroy habitat contaminate groundwater and release dust particles

I didn't really focus on too much because we're going to talk about when we talk about atmospheric pollution but

this dust particle part whenever you're digging into the soil and it's that soil dries out and it's windy you got lots of

dust that's particulate matter and it's a form of air pollution as coal reserves get smaller due to lack

of easily accessed reserves accessible reserves it becomes necessary to access coal through subsurface mining which is

very expensive okay so coal prices have gone up because of that and due to that we hit Peak coal in 2013.

all right guys I hope you have um I hope you learned something um write down any questions for me to

answer in class I'll see you all later bye