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AP Environmental Science Mr. Grant Lesson 90 - PowerPoint PPT Presentation

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AP Environmental Science Mr. Grant Lesson 90. Earth’s Mineral Resources & Mining Methods and Their Impact (Part 1). Objectives:. Define the terms placer mining and mountaintop removal mining . Outline types of mineral resources and how they contribute to our products and society.

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AP Environmental Science Mr. Grant Lesson 90

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  • AP Environmental Science

  • Mr. Grant

  • Lesson 90

Earth’s Mineral Resources


Mining Methods and Their Impact (Part 1)


  • Define the terms placer mining and mountaintop removal mining.

  • Outline types of mineral resources and how they contribute to our products and society.

  • Describe the major methods of mining.

Define the terms placer mining and mountaintop removal mining.

Placer Mining

A mining technique that involves sifting through material in modern or ancient riverbed deposits, generally using running water to separate lightweight mud and gravel from heavier metals of value.

Mountaintop Removal Mining

A large-scale form of coal mining in which entire mountain-tops are leveled. The technique exerts extreme environmental impact on surrounding ecosystems and human residents.

Outline types of mineral resources and how they contribute to our products and society.

  • Minerals we mine from the earth provide raw materials for most of the products we use everyday.

  • We mine ore for metals, as well as nonmetallic minerals and fuels.

  • Processing and refining metals through methods such as smelting is an important step between mining ore and manufacturing products.

Minerals and mining

  • We extract raw minerals from beneath our planet’s surface

    • Turn them into products we use everyday

  • Rock and resources from the lithosphere contribute to our economies and lives

  • Rock = a solid aggregation of minerals

  • Mineral = a naturally occurring solid chemical element or inorganic compound

    • It has a crystal structure, specific chemical composition, and distinct physical properties

Minerals are nonrenewable, so we need to be aware of their finite and decreasing supplies

Minerals are everywhere in our products

We obtain minerals by mining

  • We obtain minerals through the process of mining

  • Mining = in the broad sense, it is the extraction of any resource that is nonrenewable

    • We mine minerals, fossil fuels, and groundwater

  • Mining = in relation to minerals, it is the systematic removal of rock, soil, or other material to remove the minerals of economic interest

  • Because minerals occur in low concentrations, concentrated sources must be found before mining

We extract minerals from ores

  • Metal = an element that is lustrous, opaque, and malleable and can conduct heat and electricity

  • Ore = a mineral or grouping of minerals from which we extract metals

  • Economically valuable metals include copper, iron, lead, gold, aluminum

Tantalite ore is mined, processed into tantalum, and used in electronic devices

We process metals after mining ore

  • Most minerals must be processed after mining

  • After mining the ore, rock is crushed and the metals are isolated by chemical or physical means

    • The material is processed to purify the metal

  • Alloy = a metal is mixed, melted, or fused with another metal or nonmetal substance

    • Steel is an alloy of iron and carbon

  • Smelting = heating ore beyond its melting point then combining it with other metals or chemicals

Processing minerals has costs

  • Processing minerals has environmental costs

    • Most methods are water- and energy-intensive

  • Chemical reactions and heating to extract metals from ores emit air pollution

  • Tailings = ore left over after metals have been extracted

    • Pollutes soil and water

    • They may contain heavy metals or acids (cyanide, sulfuric acid)

    • Water evaporates from tailings ponds, which may leach pollutants into the environment

We also mine nonmetallic minerals and fuels

  • Nonmetallic minerals include sand, gravel, phosphates, limestone, and gemstones

    • $7 billion/year of sand and gravel are mined in the U.S.

    • Phosphates provide fertilizer

    • “Blood diamonds” are mined and sold to fund, prolong, and intensify wars in Angola and other areas

  • Substances are mined for fuel

    • Uranium for nuclear power

    • Coal, petroleum, natural gas are not minerals (they are organic), but they are also extracted from the Earth

Economically useful mineral resources

Describe the major methods of mining.

  • Strip mining removes surface layers of soil and rock to expose resources.

  • In subsurface mining, miners tunnel underground.

  • Open pit mining involves digging gigantic holes.

  • Placer mining uses running water to isolate minerals.

  • Mountaintop removal mining removes immense amounts of rock from mountaintops and dumps it into valleys below.

  • Solution mining uses water to dissolve minerals in place and extract them.

  • A great deal of mineral wealth exists in the oceans but is mostly uneconomical (so far) to reach.

Characterize the environmental and social impacts of mining.

  • Many methods of mining completely remove vegetation, soil , and habitat.

  • Acid drainage occurs when water leaches compounds from freshly exposed waste rock. It is often toxic to aquatic organisms.

  • Erosion, sediment disturbance, and other impacts add to water pollution.

  • Mountaintop removal for coal destroys forests, mountaintops, and adjacent valleys and streams.

  • Mining may have health impacts on miners and diverse social impacts on people living near mines.

Mining methods and their impacts

  • People in developing nations suffer war and exploitation because of the developed world’s appetite for minerals

  • In 2009, raw materials from mining gave $57 billion to the U.S. economy

    • After processing, minerals contributed $454 billion

    • 28,000 Americans were directly employed for mining

  • Large amounts of material are removed during mining

    • Disturbing lots of land

  • Different mining methods are used to extract minerals

    • Economics determines which method to use

Strip mining removes surface soil and rock

  • Strip mining = layers of soil and rock are removed to expose the resource

  • Overburden = overlying soil and rock that is removed by heavy machinery

    • After extraction, each strip is refilled with the overburden

  • Used for coal, oil sands, sand, gravel

  • Destroys natural communities over large areas and triggers erosion

  • Acid drainage = sulfide minerals form sulfuric acid and flow into waterways

Strip mining destroys the environment

Strip mining removes soil

Discolored water is a sign of acid drainage

A mining method: subsurface mining

  • Accesses deep pockets of a mineral through tunnels and shafts

    • The deepest mines are 2.5 mi

  • Zinc, lead, nickel, tin, gold, diamonds, phosphate, salt, coal

  • The most dangerous form of mining

    • Dynamite blasts, collapsed tunnels

    • Toxic fumes and coal dust

  • Acid drainage, polluted groundwater

    • Sinkholes damage roads, homes, etc.

A mining method: open pit mining

  • Used with evenly distributed minerals

    • Terraced so men and machines can move about

  • Copper, iron, gold, diamonds, coal

  • Quarries = open pits for clay, gravel, sand, stone (limestone, granite, marble, slate)

  • Huge amounts of rock are removed to get small amounts of minerals

  • Habitat loss, aesthetic degradation, acid drainage

    • Abandoned pits fill with toxic water

One open pit mine

One Utah mine is 2.5 mi across and 0.75 mi deep; almost half a million tons of ore and rock are removed each day

A mining method: placer mining

  • Using running water, miners sift through material in riverbeds

    • Coltan miners, California’s Gold Rush of 1849

  • Used for gold, gems

  • Debris washed into streams makes them uninhabitable for wildlife

  • Disturbs stream banks, causes erosion

  • Harms riparian plant communities

A mining method: mountaintop removal

  • Entire mountaintops are blasted off

    • The waste is dumped into valleys

  • For coal in the Appalachian Mountains of the eastern U.S.

  • Economically efficient

    • “Valley filling” = dumping rock and debris into valleys

  • Degrades and destroys vast areas

  • Pollutes streams, deforests areas, erosion, mudslides, flash floods

An area the size of Delaware has already been removed

Mountaintop removal is socially devastating

  • Mine blasting cracks foundations and walls

  • Floods and rock slides affect properties

  • Overloaded coal trucks speed down rural roads

  • Coal dust and contaminated water cause illness

  • Local politicians do not help

  • High-efficiency mining reduces the need for workers

A mining method: solution mining

  • Solution mining (in-situ recovery) = resources in a deep deposit are dissolved in a liquid and siphoned out

  • Salts, lithium, boron, bromine, potash, copper, uranium

  • Less environmental impact than other methods

    • Less surface area is disturbed

    • Acids, heavy metals, uranium can accidentally leak

A mining method: undersea mining

  • We extract minerals (e.g., magnesium) from seawater

  • Minerals are dredged from the ocean floor

    • Sulfur, phosphate, calcium carbonate (for cement), silica (insulation and glass), copper, zinc, silver, gold

  • Manganese nodules = small, ball-shaped ores scattered across the ocean floor

    • Mining them is currently uneconomical

  • Hydrothermal vents may have gold, silver, zinc

  • Mining would destroy habitats and organisms and release toxic metals that could enter the food chain

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