Geologic Resources Chapter 15. General Mining Law 1872 Encouraged mineral exploration Help develop the West – selling land Mining provides – jobs, resources,

Geologic Resources

Chapter 15

General Mining Law 1872

Encouraged mineral explorationHelp develop the West – selling land

Mining provides – jobs, resources, stimulation of economy

Environmentalist want – lease not ownership, pay royalty, clean up

Resources

Metallic – nickel, iron, gold, aluminumNonmetallic – salt, gypsum, clay, soilEnergy – coal, oil, natural gas, uranium

Ore – rock containing a metallic mineralReserve – known deposit of mineral that can be extracted for a profit

Resources in the ocean

Black smokers – hydrothermal vents that deposit minerals in tall chimneylike stacks

Manganese nodules – found on the ocean floor, they contain 30-40% manganese and other important minerals

Magma

Black smoker

Sulfidedeposit

White crab White clam

Tube worms

Whitesmoker

Fig. 14.3, p. 322

Removing mineral resources

Shallow deposits are removed through surface mining

Open-pit miningDredgingArea strip miningContour strip mining

Deep deposits through subsurface mining

Contour Strip Mining

Fig. 14.4d, p. 324

Area Strip Mining Fig. 14.4c, p. 324

Dredging Fig. 14.4b, p. 324

Open Pit Mine Fig. 14.4a, p. 324

Fig. 14.5b, p. 325 Room-and-pillar

Underground Coal Mine Fig. 14.5a, p. 325

Fig. 14.5c, p. 325 Longwall Mining of Coal

Mining

Overburden is removed to expose mineral, disposed of as spoil

Surface mining accounts for about 90% of non fuel mining and 60% of coal

Surface Mining Control and Reclamation Act 1977 – companies had to restore most of the surface to pre-mining conditions

Environmental effects of mining

Scarring and disruption of land surfaceCollapse and subsiding of landWind and water caused toxin-laced mining wastesAcid mine drainage

Sulfuric acid from rain water combinationRun-off to streamsDestroys aquatic life

Toxic chemical emission into air

Percolation to groundwater

Leaching of toxic metalsand other compounds

from mine spoil

Acid drainage fromreaction of mineralor ore with water

Spoil banks

Runoff ofsediment

Surface MineSubsurfaceMine Opening

Leaching may carryacids into soil andgroundwater

supplies

Fig. 14.7, p. 326

Steps Environmental Effects

exploration, extraction

MiningDisturbed land; mining accidents;health hazards; mine waste dumping;oil spills and blowouts; noise;ugliness; heat

Solid wastes; radioactive material;air, water, and soil pollution;

noise; safety and healthhazards; ugliness; heat

Processing

transportation, purification,manufacturing

Use

transportation or transmissionto individual user,

eventual use, and discarding

Noise; uglinessthermal water pollution;

pollution of air, water, and soil;solid and radioactive wastes;

safety and health hazards; heat

Fig. 14.6, p. 326

After mining

Ore contains desired metal and waste called gangue

Removed gangue is piled into heaps called tailings

Smelting is then used to separate the metal minerals

Smelting

Smelters create a large quantity of air pollution

They also produce liquid and solid hazardous waste that must be disposed

Companies are trying to reduce pollution, lower costs, and decrease liability

How much is there?

Depletion time is the time it takes to use up 80% of the reserve (profitable)

Reserve to production ratio – how long will the known reserves last at current rates of production

Present Depletiontime A

Depletiontime B

Depletiontime C

Time

Pro

du

ctio

n

C

B

A

Recycle, reuse, reduceconsumption; increasereserves by improvedmining technology,higher prices, andnew discoveries

Recycle; increase reservesby improved miningtechnology, higher prices,and new discoveries

Mine, use, throw away;no new discoveries;rising prices

Fig. 14.9, p. 329

The big three

US, Germany, and Russia

Only 8% of the population

Use 75% of the most common metals

US uses 25% of the fossil fuels (cars)

Fig. 14.10, p. 329

Ocean mining

Will the ocean supply us with enough minerals?They are there, but too expensive currently

Energy resources

99% of energy used to heat the earth and all the buildings comes from the sun

The sun also creates renewable energy resources – wind, flowing water, biomass

The rest

The last 1% comes from fuel resources

Fossil fuels make up the vast majority

Petroleum, coal, and natural gas

A small portion also comes from nuclear sources

Mined coal

Pipeline

Pump

Oil well

Gas well

Oil storage

CoalOil and Natural Gas Geothermal Energy

Hot waterstorage

Contourstrip mining

PipelineDrillingtower

Magma

Hot rock

Natural gasOil

Impervious rock

Water Water

Oil drillingplatformon legs

Floating oil drillingplatform

Valves

Undergroundcoal mine

Water is heatedand brought upas dry steam or

wet steam

Waterpenetratesdownthroughtherock

Area stripmining

Geothermalpower plant

Coal seam

Fig. 14.11, p. 332

Shifts in energy usage worldwide

During the 20th century

Coal use dropped from 55 to 22%Oil increased from 2 to 30%Natural gas rose from 1 to 23%Nuclear rose from 0 to 6%Renewable (wood and water ) dropped from 42 to 19%

Way to go US

The U.S. is the world’s largest energy consumerWe use 25% of the world’s energy (even though we only have 4.5% of the total population)India with 17% of the population only uses 3% of the world’s commercial energy91% of the U.S.’s energy in nonrenewable

EnergyNet energy refers to the amount of useful energy minus the energy needed to find, extract, process, concentrate, and transport to the users

Nuclear energy has a low net energy ratio because it is expensive to extract and process uranium, convert it into a fuel, build and operate the plant, and dismantle and deal with radioactive plants and waste

Oil, Oil everywhere and not a drop to drink

Extracted as crude oil or petroleum, a thick liquid consisting of hydrocarbons, and some sulfur, oxygen and nitrogen impurities

Produced from decayed plant and animal material over millions of years

Oil continued

Normally crude oil is not found in underground pools, but is spread out in the pores and cracks within rock deep beneath the ground

Primary recovery – drill a hole and pump out the light weight crude that fills the hole

Oil continued

Secondary recovery – pumping water into the well to force oil out of the pores The oil and water mixture is separated after pumping

Only about 35% of the oil is removed by primary and secondary recovery

Oil continued

Tertiary recovery – either a heated gas or a liquid detergent is pumped into the well to help remove more oil

Tertiary is expensive

Oil continued

At the refinery oil is converted into petrochemicals and used as a resource to create industrial organic chemicals, pesticides, plastics, synthetic fibers, paints, medicines and more.

OPEC – organization of petroleum exporting countries control 67% of the worlds oil and maintain control over pricing

Diesel oil

Asphalt

Greaseand wax

Naphtha

Heating oil

Aviation fuel

Gasoline

Gases

FurnaceFig. 14.16, p. 337

Heatedcrude oil

Low land use

Easily transportedwithin and between countries

High netenergy yield

Low cost (withhuge subsidies)

Ample supply for42–93 years

Advantages

Moderate waterpollution

Releases CO2 when burned

Air pollutionwhen burned

Artificially low price encourageswaste and discourages search for alternatives

Need to findsubstitute within50 years

Disadvantages

Fig. 14.21, p. 340

Oil continuedOil shale is a fine grained sedimentary rock containing solid combustible organic material called kerogen

Shale oil is made from heating oil shale

Tar sand contains bitumen another combustible organic materialBoth are more expensive than crude recovery

Advantages Disadvantages

Moderate existingsupplies

Large potentialsupplies

High costs

Low net energyyield

Large amount ofwater needed toprocess

Severe land disruption fromsurface mining

Water pollution from mining residues

Air pollution when burned

CO2 emissionswhen burned

Fig. 14.25, p. 342

Natural Gas

Mostly CH4 methane with some ethane, propane and butane and small amounts of hydrogen sulfide (toxic)

LPG (liquefied petroleum gas) the propane and butane are removed from natural gas and stored under pressure

How long will it last?

Natural gas should last about 125 years worldwide

About 75 years in the US

Overall about 200-300 years with rising prices, better technology, and more discoveries

Advantages Disadvantages

Good fuel forfuel cells andgas turbines

Low land use

Easily transportedby pipeline

Moderate environ-mental impact

Lower CO2 emissions thanother fossil fuels

Less air pollutionthan otherfossil fuels

Low cost (withhuge subsidies)

High net energyyield

Ample supplies(125 years)

Sometimes burned off andwasted at wellsbecause of lowprice

Shipped acrossocean as highlyexplosive LNG

Methane(a greenhouse gas) can leakfrom pipelines

Releases CO2

when burned

Fig. 14.26, p. 342

The future of power plants

There is currently being developed a combined cycle natural gas electric power plant with 60% efficiency

This is much better than 32-40% efficiency of others (coal, oil, nuke)

What other reasons make it better?

Coal

Solid fuel of combustible carbon, most formed 285-360 million years agoPeat – 1st, low heat contentLignite – 2nd, low heat and low sulfurBituminous Coal – 3rd, high heat and abundant supply, high sulfurAnthracite – 4th, high heat, low sulfur, limited supply

Increasing moisture content

Increasing heat and carbon content

Peat(not a coal)

Lignite(brown coal)

Bituminous Coal(soft coal)

Anthracite(hard coal)

Heat

Pressure Pressure Pressure

Heat Heat

Partially decayedplant matter in swampsand bogs; low heatcontent

Low heat content;low sulfur content;limited supplies inmost areas

Extensively usedas a fuel becauseof its high heat contentand large supplies;normally has ahigh sulfur content

Highly desirable fuelbecause of its highheat content andlow sulfur content;supplies are limitedin most areas

Fig. 14.27, p. 344

Coal for energy

Coal provides about 22% of the commercial energy in the world

It is used to create 62% of the worlds electricity75% of the worlds steelChina is the largest user followed by USUS creates 52% of energy with coal

Advantages Disadvantages

Low cost (with huge subsidies)

High net energyyield

Ample supplies(225–900 years)

Releases radioactive particles and mercury into air

High CO2 emissionswhen burned

Severe threat tohuman health

High land use (including mining)

Severe land disturbance, air pollution, andwater pollution

Very high environmentalimpact

Fig. 14.28, p. 344

The cost of coalLand disturbanceAir pollution (especially sulfur dioxide)Co2 emissionsWater pollution

Electricity production (coal) is the second largest producer of toxic emissions

The most deadly emission is mercury

Wonderful coal

60,000 babies annually are born with brain damage due to mercury exposure, typically from pregnant mothers eating mercury in fish

Coal also releases more radioactive particles into the atmosphere than nuclear power plants

Also, acid rain and methane release

Coal in the US

Air pollutants kill thousands (estimates are from 60,000 – 200,000)Cause at least 50,000 cases of respiratory diseaseCost several billion dollars in property damage

The good news

Fluidized bed combustion is reducing the amount of pollution

Hot air is blown under a mix of crushed limestone and coal while it is burntThis removes most sulfur dioxide, reduces Nox and burns the coal more efficiently and cheaply

Calcium sulfateand ash

Air

Air nozzles

Water

Fluidized bed

Steam

Flue gases

Coal Limestone

Fig. 14.29, p. 345

Coal gasification

Solid coal can be converted into synthetic natural gas (SNG)

It can also be made into synfuels (liquids) through coal liquefaction

Neither is expected to play a major role in our future energy needs

Raw coal

Pulverizer

Air oroxygen

Steam

Pulverized coalSlag removal

Recycle unreactedcarbon (char)

Raw gases CleanMethane gas

Recoversulfur

Methane(natural gas)

2CCoal

+ O2 2CO

CO + 3H2 CH4 + H2O

Remove dust,tar, water, sulfur

Fig. 14.30, p. 345

Advantages Disadvantages

Large potentialsupply

Vehicle fuel

Low to moderatenet energy yield

Higher cost thancoal

High environmentalimpact

Increased surfacemining of coal

High water use

Higher CO2 emissions than coal

Fig. 14.31, p. 346

Nuclear Energy

Uranium 235 and plutonium 239 are split (nucleus) to release energyThe reaction rate is controlledThe energy heats water and turns it to steamSteam spins turbines connected to generators which create electricity

LWR light water reactors

All US reactors are of this type, so know it

Periodic removaland storage of

radioactive wastesand spent fuel assemblies

Periodic removaland storage of

radioactive liquid wastes

Pump

Steam

Small amounts of Radioactive gases

Water

Black

Turbine Generator

Waste heat Electrical power

Hot water output

Condenser

Cool water input

Pump

Pump Wasteheat

Useful energy25 to 30%

WasteheatWater source

(river, lake, ocean)

Heatexchanger

Containment shell

Uranium fuel input(reactor core)

Emergency coreCooling system

Controlrods

Moderator

Pressurevessel

Shielding

Coolantpassage

Fig. 14.32, p. 346

CoolantCoolant

Hot coolantHot coolant

Nuclear is out of favor

The US has not ordered a new nuclear facility since 1978, and 120 ordered since 1973 were cancelledMost countries are phasing out nuclear plants or are not continuing to expand their programs, except China who is trying to move away from dependence on coal

Why is nuclear not meeting expectations?

Multi-billion dollar cost of constructionStrict govt. safety regulationsHigh operating costsMore malfunctions than expectedPoor managementPublic concern after Chernobyl, and Three Mile IslandInvestor concern about economic feasibility

Low risk of accidents because of multiplesafety systems(except in 35 poorly designed and run reactors in former SovietUnion and Eastern Europe)

Moderate land use

Moderate landdisruption andwater pollution(without accidents)

Emits 1/6 asmuch CO2 as coal

Lowenvironmentalimpact (withoutaccidents)

Large fuelsupply

Spreads knowledge and technology for building nuclear weapons

No acceptable solution for long-term storage of radioactive wastes and decommissioning worn-out plants

Catastrophic accidents can happen (Chernobyl)

High environmental impact (with major accidents)

Low net energy yield

High cost (even with large subsidies)

Advantages Disadvantages

Fig. 14.35, p. 349

Coal

Ample supply

High net energyyield

Very high airpollution

High CO2emissions

65,000 to 200,000deaths per yearin U.S.

High land disruption fromsurface mining

High land use

Low cost (with huge subsidies)

Nuclear

Ample supplyof uranium

Low net energyyield

Low air pollution(mostly from fuelreprocessing)

Low CO2emissions(mostly from fuelreprocessing)

About 6,000deaths per year in U.S.

Much lower landdisruption fromsurface mining

Moderate land use

High cost (with huge subsidies)

Fig. 14.36, p. 349

ChernobylIn the former Soviet Union, April 26, 1986 the reactor core went out of control and exploded sending a cloud of radioactive dust into the atmosphere3,576 – 32,000 people died400,000 forced to evacuate62,000 square miles still contaminatedMore than 500,000 people exposed to high level radiationCost the govt. $385 billion

Three Mile Island

March 29, 1979 in Harrisburg, Penn.Coolant failed and core meltedRadioactive material escaped into air50,000 people evacuatedLuckily the radiation release was believed to be too low to cause death or cancerCleanup has cost $1.2 billion so far

What do we do with the waste?

Low level radioactive waste must be stored for 100-500 years until it reaches a safe level (does not give off harmful ionizing radiation)This was done by sealing the waste in steel drums and dumping it in the oceanToday some countries (US) stores the waste at govt. run landfills, but no one wants to live anywhere near them

Waste container

Steel wall

Steel wall

Severalsteel drumsholding waste

Lead shielding

2 meters wide2–5 meters high

Fig. 14.38a, p. 351

Clay bottom

Up to 60deep trenchesdug into clay.

As many as 20flatbed trucksdeliver wastecontainers daily.

Barrels are stackedand surroundedwith sand. Coveringis mounded to aidrain runoff.

Fig. 14.38b, p. 351

And the bad stuff?

High level radioactive waste must be stored for 10,000 to 240,000 years until it reaches a safe levelCurrently most is stored at the reactor site, sealed in drums, in pools of water

Proposed methods of disposal

Bury deep underground – this is the leading strategy currentlyShoot it into space/SunBury it deep in the Antarctic ice sheetDump it into descending subduction zonesBury in deep mud deposits on ocean floorConvert into less harmful isotopes (currently we do not have the technology)

Fig. 14.39a

, p. 352

Slide 52

Personnel elevator

Air shaft

Nuclear waste shaft

2,500 ft.(760 m)deep

Fig. 14.39b, p. 352

Slide 53

Storage Containers

Fuel rod

Primary canister

Overpack container sealed

Fig. 14.39c, p. 352

Radioactive contamination

The EPA suggests that there are 45,000 sites in the US (20,000 belong to the DOE)It is expected to cost over $230 billion over the next 75 yearsMore than 144 highly contaminated weapons construction sites will never be completely cleaned