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Chapter 16 Mining and Minerals
Terms in this set (28)
inorganic, naturally occurring, solid material with a definite chemical composition, and with its atoms arranged in a regular, repeating geometric pattern
Made up of a single element or a compound
rock or mineral that contain economically desirable metals or non-metals
Most minerals are compounds composed of two elements:
oxygen and silicon which makes silica makes up 75% of the earth's crust
Give examples of some minerals and some ores
Mineral- gold, copper, quartz, calcite, fluorite
Ore- Hematite and Magnetite (iron), Galena (lead), Bauxite (aluminum)
What are metallic mineral characteristics?
Opaque (can not see through it)
Ductile- has the ability to be stretched and pulled into wires
Malleable- can be hammered and shaped without breaking
Act as a Conductor- allows electricity and heat to flow through them
What are some non-metallic mineral characteristics?
May have shiny or dull surfaces
May allow light to pass through
How are minerals formed?
-cooling of magma
Formation that occurs when hot, subsurface waters that contain dissolved minerals flow through cracks in rocks they dissolve minerals that they come in contact with. New minerals then crystallize and fill rock fractures (called veins) with ore.
Mineral formation that occurs as water washes over land it dissolves salts and carries them to the sea or inland lakes. When the water evaporates deposits are left behind. Ex. Halite (Salt), gypsum
Describe how geologists find a mineral deposit
Data on magnetism, gravity, radioactivity
Use aerial photography
They study the information gathered from the above techniques then decide to drill for core samples.
What is overburden?
Layers of rock, soil and vegetation removed from the surface to uncover mineral deposits
A type of surface mining operation in which explosives are used to break open the earth. Once open, blocks of earth are continually dug from the surface and brought up by trucks and other machines.
Describe mountain top removal
In order to reach coal seams the top of the mountain or the "overburden" is broken up and removed by blasting.
Once the rock surrounding the coal is blasted off, in what is known in the industry as "shoot and shove," the excess rock and earth is dumped over the side of the mountain into the valleys below, often burying the streams that run through them
What are four types of surface mining?
Mountain top removal
Describe how a placer deposit occurs
When rock weathers by erosion, wind and water it can expose a mineral. That mineral may be carried into certain surface deposits or placer deposits.
Often placer deposits are where currents in a river are weak so the mineral drops to the bottom
Involves scraping or vacuuming desirable minerals from ocean floors, lake bottoms, and streambeds
What are the environmental
Issues with dredging?
Massive removal of organisms and nutrients alter food webs,
increase sediment in water
Questions about how dredging effects currents, coral reefs and beaches
What are three ways minerals are mined below the surface?
Room and pillar
A type of subsurface mining where the excavation of a series of "rooms" into the mineral bed, leaving "pillars" or columns of coal to help support the mine roof. The mineral is broken up by explosives, loaded onto a vehicle by a mechanized loading machine.
Room and Pillar
Subsurface mining where a rotating shear on the mining machine shaves from blocks or panels of mineral in a back-and-forth motion, similar to that of a meat slicer, and dumps the broken coal onto a conveyor belt that extends across the longwall. As the mining machine advances, the roof behind it caves in.
What is extraction and what are the main methods of doing it?
Extraction is the process ore undergoes to release the mineral from the host rock.
Extraction is done by chemical means, physical -smelting or crushing the rock and using its physical properties to separate the desired mineral from the host rock
Describe the chemical method to extract the mineral from the gangue.
ores that contain the metals (normally gold and copper) are taken from the earth, crushed into very small pieces then put onto a pad with an asphalt or impervious plastic sheet. Next a cyanide solution is sprayed on the ore.
The cyanide then percolates or drips down the ore and leaches out the metal. The metal, which is now in solution, drains off the pad into a pond. From the pond, the metal is removed from the solution.
Describe the steps to smelting.
heat the ore till it melts
add flux to bind the impurities
separate out the metal
The metal then falls to the bottom and the impurities are taken out.
What are some environmental issues with smelting
Contributes about 8% of the worldwide sulfur dioxide. Sulfur dioxide causes acid precipitation.
Also emits large volumes of arsenic and lead into the atmosphere. These metals form large areas where plant and animal life cannot live. Chloroplasts in plants become damaged, so they can't produce or store food. Which in turn disturbs the entire food web
the process of returning the land to its original or better condition after mining is completed
What are the economic and environmental benefits of recycling metals?
It is cheaper to rework recycled metal than to mine and process new metal.
Less mining leads to reduced topsoil loss and habitat destruction.
What are the environmental impacts of mining?
Air and noise pollution
Displacement of wildlife
Erosion and sedimentation
Underground mine fires
What are three ways to minimize the impact of mining on the environment?
Recycling- waste materials are treated and used to make more products
Reuse- using the same material over and over again
Substitution- use an abundant material instead of one that has limited quantities