Chapter 16, Section 2-
Mineral Exploration and Mining
I.Mineral Exploration
MINING: The process of obtaining mineral resources from the Earth.
What do we mine? Coal, diamonds, aluminum, copper, salt, sulfur, granite,
Ore - a naturally occurring solid material from which a metal or valuable mineral can be profitably extracted.
(start around 3:00 –.Stop at 9:00)
surface-strip mining – (for sand and coal )______
surface-open pit mining – (copper)______
-Placer mining – (solution mining) (gold, diamonds) ______
-Subsurface mining - ______
I. Subsurface Mining- Is a type of mining performed when the ore deposits are found 50 meters (164 ft.) or more beneath Earth’s surface.
- Longwall Mining – What is longwall mining? –definition -
a cutter moves under a long panel of hydraulic roof supports and slowly chips away at coal seam
During this type of mining, a machine called a shearer moves back and forth across the face of a coal seam. The wall of the seam may be 300m (984 ft.) long. As the shearer breaks the coal from the face of the seam, the coal is collected in a conveyor, which conveyor transports the coal out if the mine
video- - Room-and-Pillar Method-rooms in the coal seam are cut out with pillars left as support, but the pillars of coal are rarely recovered
- Solution Mining – What is solution mining? - – definition -
______
______
video -
It is an economical mining method used to mine potash, salt and sulfur. In solution mining, hot water is injected into the ore and dissolves it. Compressed air is then pumped into the dissolved ore, and air bubbles lift it to the surface.
II. Surface Mining- this mining method is used for ore that is located close to the Earth’s surface.
Open-pit mining is a method that is used to mine large quantities of near-surface ore such as coal and copper. The ore is mined downward, layer by layer.
- Strip Mining (Surface Coal Mining) – In the first step, large machines are used to remove the overburden (a rock that covered near-surface coal deposits). The overburden could be 50 m (164 ft.) deep and 1km long. Next, loaders enter the pit and remove the exposed coal seam. The last step is to fill in the whole with the same overburden that was removed at the first step.
- Quarrying- Building stones such as granite and marble are mined in quarries. Sand, gravel, and crushed rock, known as aggregate are the main product of quarrying, which also produce clay, gypsum and talc. ( limestone quarrying - )
- Solar Evaporation- About 30 % of the world’s salt comes from the solar evaporation process. This process consists of placing seawater into enormous, shallow ponds. When the sun evaporates the seawater, sodium chloride concentration increases and reaches over 25%, which causes a formation of salt crystals. With further evaporation, layers of crystalline salt called halite, build up. After the desired thickness is reached, harvesting begins. (This video is about harvesting salt- )
D. Solution mining – pump boiling water down then salt (or other minerals) dissolves and
then it is pumped back out.
III. Case Study- Hydraulic Mining in the California Goldfields (summary) -
-Millions of years ago, river-bearing gold flowed across present-day northern California. But over time, a geological process formed Sierra Nevada Mountains and buried the gold. People were trying to recover the gold by finding a method to remove the 60meters of soil. They used hydraulic mining. However, it proved to be an environmental disaster because the muddy water and the sediments polluted the river with silt. The silt traveled downstream all the way to San Francisco and into the Pacific Ocean. Around 3million kg of mercury were released downstream which poisoned fish, amphibians, and invertebrates.
IV. Placer Mining(solar evaporation)
Placer deposits-The minerals are concentrated by wind and water into surface
deposits called placer deposits. It may form along coastlines from heavy minerals
that wash down to the ocean in streams. The minerals are mined by dredging.
V. Smelting –
During this process, crushed ore is meltedat high temperatures in furnaces to separate impurities from molten metal.
•Smelting is where crushed ore is melted at high temperatures in furnaces to separate impurities from molten metal.
•A material called Flux bonds with impurities and separates them from the molten metal
•Molten metal falls to the bottom of the furnace and is recovered.
•The Slag (impurities) form a layer on the top
•Gases (sulfur dioxide) are captured so they do not enter the environment
VI. Undersea Mining
-The ocean floor contains significant mineral resources:
diamonds, precious metals such as gold and silver, mineral ores, sand and gravel.
______
Chapter 16, Section 3: Mining Regulations and Mine Reclamation
I. The Environmental Impacts of Mining
-In the U.S., the federal and state governments and mining companies are spending billions of $ to clean up abandoned mines.
A. Air and Noise Pollution
-Surface mining can cause both air and noise pollution, by removing, loading, hauling, and dumping soil overburden produce dust and noise by the equipment.
B. Water Contamination
-Water resources can be negatively impacted by mining. Water can pick up or dissolve toxic substances like arsenic. This water can end up into streams where they can harm or kill aquatic life. Also water contamination occurs from this process is called Acid Mine Drainage (AMD). Acid mine drainage - the overburden (what they dig out to get to what they are looking for) has high amounts of sulfur so when you have rain, you get highly acidic water that is also full of heavy metals. BAD!!!!!!
C. Displacement of Wildlife
-Removing soil from a surface mine site strips away all plant life. Animals will leave their area if they lose their natural habitat. New ecosystems are established when the soil is returned on the original location after the mine is closed.
D. Erosion and Sedimentation
-Excess rock from mines is sometimes dumped into large piles called dumps.The running water can erode the dump and the sediments may harm water quality and aquatic life.
E. Soil Degradation
-Soil at a mine site gets removed from the uppermost layer downward. The soil gets stored and after mining the area, the layers of soil are arranged according to their original location (the top soil layer is returned at the top- most nutrition rich layer important for plant growth and development).
F.Subsidence
-The sinkingof regions of the ground with little or no horizontal movement is called subsidence. It occurs when pillars that have been left standing in mines collapse or the mine roof/floor fails.
-sink holes
G. Underground Mine Fires
-Are fires that start in underground coal seams are one of the most serious environmental consequences of coal mining. These fires are heard to put out (it may take decades or centuries to burn themselves out. (One is still burning since in Centralia, PA.)
- II. Mining Regulation and Reclamation (start at 10:30 )
4 federal laws that regulate mining activities in the United States
1. Clean Water Act
2. Safe Drinking Water Act
3. Comprehensive Response Compensation and Liability Act (CRCLA)
4.Surface Mining Control and Reclamation Act of 1977 (SMCRA)
A. Reclamation-The process of returning land to its original or better condition after mining. The SMCRA (Surface Mining Control and Reclamation Act of 1977) regulates surface coal mining on public and private land by minimizing the surface effects of coal mining on the environment.
B. State Regulation of Mining-
Mining companies must obtain permits from state environmental agencies before mining a site.
ENERGY RESOURCES NOTES
For thousands of years, people have used natural resources for energy. For example, the earliest known use of fire dates back to 460,000 BC somewhere in China.
What other sources of energy do people use?______
Identify which energy resources above are:
Renewable: these will _not_ be depleted due to our use of them. Examples: Solar, tidal, wind, hydro
Non-renewable: these _will_deplete due to our use (at current rates.) Examples: oil, coal, natural gas
I. What is a fossil fuel? highly combustible substances formed from the remains of organisms from past decades. (generally through compression and heat). THEY ARE READILY AVAILABLE AND RELATIVELY INEXPENSIVE! THE PROBLEM IS THAT WE ARE USING THEM FASTER THAN THEY ARE FORMED!
United States: 24% of all our energy used
We have 27% of the world’s reserves of coal (more than anyone) / United States: this is the most heavily used: 40% of all energy
We do not have any significant supply. Saudi Arabia has the most (22% of world’s reserves) / United States: 25% of all our energy used.
We have 2.9% of the world’s supply. Russia has the most (26% of the world’s reserves)
- COAL:
- A fossil fuel made of organic matter
(mostly from plants) that was put under high pressure to form dense, solid carbon material. - There is enough coal remaining globally to supply current needs for another century or so.
- Coal is considered the most polluting of the fossil fuels
Coal is removed from the ground through the process of mining.
In order for a company to mine materials from the ground, they must locate an ore:
Ore: Coal material that is high enough in quantity and quality to be profitable to mine
There are 4 different types of coal ore that vary in quality. These are:
Lignite(least valuable) / Sub-bituminous / Bituminous / Anthracite
(most valuable)
a. Lignite is the least compressed, has the most impurities, and the least energy. It also releases the most carbon dioxide emissions when burned.
b. Anthraciteis the mostcompressed, fewest impurities, and most energy. It releases fewer carbon dioxide emissions when burned.
Strip Mining: (surface mining)- Heavy machinery moveslarge amounts of earth to expose coal below.
- After the coal is removed, the pits are refilled with earth that has been removed (called spoils).
- Surface mining causes a lot of erosion problems and creates unstable ground around the spoils.
- Tunnels/shafts dug deep into ground, coal is removed and shipped to the surface.
- This is the most dangerous form of mining for workers.
- Empty shafts are often filled in with spoils and/or slurry (mix of coal and water)
- This type of mining creates unstable earth and groundwater contamination
- OIL
- (AKA Petroleum or crude oil) Oil is a mixture of 100’s of different carbon-based chemicals
- Oil is formed under high temperature and pressure about 1.5-3 km below the surface. Often found in the same rock formation as natural gas.
- Formed from the decay of marine organisms millions of years ago.
- 2nd most polluting fossil fuel
Petroleum- Oil that is pumped from the ground is also known as crude oil or petroleum. Products made from petroleum are called petroleum products (fuels, chemicals, plastics).
Exploratory drilling: Small and deep holes are drilled to determine the size/area of an oil deposit. _
Extraction:
- When oil is drilled and pumped from a deposit for profit.
- At first the oil may come to the surface due to natural pressure from the earth. To get the rest of the oil, you need to spend energy to bring the oil to the surface
Hubbert’s Peak:
- It is widely accepted by scientists that production of a finite resources, such as oil, starts as zero and rises until it peaks an then declines until the resources is completely depleted.
- Hubbert’s peak is an estimation of when the world will reach peak oil production. This means that when we reach the Hubbert Peak, we will have used half of all the recoverable oil that ever existed on our planet.
- In 1956, Shell Oil scientist, Dr. Hubbert, predicted that US oil production would peak in 1970 – he was right. He also predicted world oil production would peak in 1995 – he was close but not as accurate.
GLOBAL PEAK OIL
3. NATURAL GAS
- Made primarily ofmethane (CH4) and other volatile hydrocarbons
- Fastest growing source of fossil fuel used today.
- ¼ of global commercial energy consumption.
Estimated 60 year supply remains globally. - Least polluting fossil fuel
About 20%of the world’s nonrenewable energy comes from natural gas (methane, CH4)
Natural gas is transported through pipelines and it is used to heat homes. Vehicles that run on natural gas require fewer pollution control (cleaner than coal and oil).
Two ways that Natural Gas isFormed:
- Natural Gas (Biogenic form):
- Pure methane (CH4)
- Created at shallow depths through anaerobic decomposition of organic matter by bacteria. “Swamp Gas” that you may have smelled.
- Also formed in landfills and can be extracted using a series of wells and a vacuum system. It canbe used to produce electricity, used as an alternative to fossil fuels, or refined and injected into the natural gas pipeline
- Methane can also be generated by the fermentation of organic matter including manure, wastewater sludge, municipal solid waste (including landfills), or any other biodegradable feedstock under anaerobic conditions.
- Natural Gas (Thermogenic form):
- Formed from compression of buried organic matter that has been under a lot of heat and pressure about 3 km below the surface of the earth.
- May form in association with crude oil that is altered by heating.
Not pure methane (methane + hydrocarbons from crude oil)
How do we benefit from fossil fuels? What would you have to give up if there were none?
Transportation (including planes, cars, trains and buses) are fueled by fossil fuels. All devices that require electricity require burning of fossil fuels to power generators.
Environmental Impacts of Fossil Fuel Use:
Although we use fossil fuels daily, their use has many damaging effects on the environment as well as on human health.
- Air Pollution and Climate Change: burning fossil fuels emits
carbon dioxide the leading greenhouse gas contributing to global warming
- AcidDrainage: When mining for coal (and other materials), chemical runoff into waterways can occur. Minerals can react with oxygen in air to form sulfuric acid.
- Oil Spills: when drilling for oil (offshore, especially) or transporting oil, spills can occur.
- Habitatdestruction– when mining any material, habitats are disturbed or completely destroyed.
Energy Conservation: practice of reducing energy use to extend the lifetime of our existing supplies of non-renewable energy resources. Also serves to reduce emissions
- Insulation_- house, hot water heaters, pipes, etc.
- Energy saving devices, appliances, lightbulbs, using a power strip for tv’s, radios, cd players, etc to reduce “phantom load”
- using less hot water – shorter showers, less water in washing machines (or cold water only) Flash-heat hot water heaters. = less hot water used = less energy used
- thermostat: decrease 2-3 degrees in winter, increase 2-3 degrees in summer to reduce overall energy consumption Or – do not use A/C at all – use fans, etc.
- Drive less, or use more efficient means of transportation. Bikes, public transit, hybrid cars, etc.
Alternative Energy Resources:
- Nuclear: energy due to the splitting (fission of the nucleus of atom(s). All current methods involve heating a working fluid such as water, which is then converted into mechanical work for the purpose of generating electricity. Today, more than 15% of the world's electricity comes from nuclear
Nuclear Energy- is the energy within the nucleus of an atom. In nuclear power plants, atoms of the element uranium are used as the fuel.
Nuclear Fission- the collisions cause the nuclei to split in a process called nuclear fission. It releases a tremendous amount of energy and more neutrons, which collides with more uranium nuclei.
A nuclear reactor is surrounded by a thick pressure vessel that filled with a cooling fluid. The pressure vessel is designed to contain the fission products in case of an accident. Thick concrete walls also surround reactors. The reactor contains uranium pellets that are bombarded with neutrons. This chain reaction releases energy.
- The Advantagesof Nuclear Energy
-Nuclear fuel is very concentrated energy source
-Nuclear power plants don’t produce greenhouse gasses.
-When operated properly, nuclear power plant releases less radioactivity than coal-fired power plants do.
-Many countries with limited amounts of fossil fuel reserves rely on nuclear energy
- Why Aren’t We Using More Nuclear Energy?
It is very expensive to build and maintain a safe nuclear reactor.
c. Storing Waste – a concern!
-It is difficult to find a safe place to store nuclear wastes. The uranium waste remains radioactive and dangerous for organism’s health for thousands of years. Scientists are trying to find ways of more safe and efficient storage of nuclear waste.
- Safety Concerns
If the nuclear power plant is poorly designed, the fission process can potentially get out of control. An example is Chernobyl nuclear accident that occurred in 1986. HUMAN ERROR – generator got too hot.
- The Future of Nuclear Power
Nuclear Fusion- It is a possible future energy source that occurs when lightweight atoms nuclei combine to form a heavier nucleus and release tremendous amounts of energy. Nuclear fusion powers all the stars, including the sun.