1. Mining & Mineral Resources
Chapter 16, Section 2: Mineral Exploration & Mining
Standards: SEV4a, b, e

2. What are the steps in harvesting minerals?
Prospecting- finding places where ores occur
Mine exploration & development- learn whether ore can be extracted economically
Mining- extract ore from ground
Extraction- separate ore minerals from other mined rock
Smelting & refining- extract pure mineral from ore mineral (get the good stuff out of waste rock)
Transportation- carry mineral to market
Marketing & sales- find buyers & sell the mineral

3. How do we know where mineral deposits are located?
Airplanes can carry instruments that detect
Patterns of gravity
Magnetism
Radioactivity
Data is collected, satellite images are taken, and a geologic map is created.
Rock samples are taken & analyzed for their content & grade
Test holes are drilled to create a 3D estimate of the extent of the ore
This will tell the driller if the amount and grade of ore is high enough to warrant the cost of opening a mine.
How Much Does a Mine Cost?
Images of the Saline Valley in California.
Left picture- red indicates trees, white indicates snow
Middle picture- short wavelengths used to identify types of rocks
Right picture- thermal infrared used to identify types of rocks that contain valuable minerals. Red indicates quartz

4. 3 Types of Mining
Subsurface mining
Surface mining
Placer mining

5. A. What is subsurface mining?
Mining of ore deposits 50m or more below Earth’s surface. (This is as long as an Olympic size pool)
3 types of subsurface mining:
Room & Pillar mining
Longwall mining
Solution mining

6. 1. Room & Pillar Mining Coal & Salt can be mined this way
“Rooms” are cut into a coal seam. Coal seam is a long, wide, layer of coal.
The “walls” of the room act as pillars to prevent collapse.
After all rooms of coal removed, the pillars are taken down starting with farthest away.

7. 2. Longwall mining
A shearer machine moves back and forth along the coal seam.
Sheared coal drops onto a conveyor belt and exits the mine
Hydraulic roof supports are used to prevent collapse
Middle picture is the shearer scraping a coal seam.
Bottom picture is the hydraulic roof support

8. 3. Solution Mining Potash, salt, sulfur are soluble in water
Hot water is injected into ore
Ore is dissolved
Removal of ore from water:
Compressed air pumped into dissolved ore and ore trapped in air bubbles that rise to surface… or…
Water evaporates from dissolved ore leaving ore behind.

9. B. What is surface mining?
Used when ore deposits are located close to Earth’s surface
3 types
Open Pit Mining
Quarrying
Solar Evaporation

10. 1. Open Pit Mining
Soil & rock (overburden) are removed from top of ore deposit
Use explosives or heavy machinery
AKA- mountain top removal
Loaders remove the exposed coal
Pit is then refilled with overburden & covered with soil.
Some types of ore are taken to heap leaching ponds where mineral is removed from the ore rock.
Gold miners used to use mercury to extract gold but proved very poisonous to animals & plants
Now gold is extracted from ore rock using cyanide. Cyanide is also very poisonous.
Cyanide is very poisonous but does not accumulate in ecosystems like mercury which is probably why it is used.
Bottom picture: Open pit gold mine with heap leaching cyanide ponds down below.

11. Machine used in open pit mining
This would make an awesome Transformer!
Machine used in open pit mining
Bucket Wheel Excavator- cost $184,400,000
Takes 5 people to operate it, moves 10 meters per minute, power lines have to be removed when moving it.

12. 2. Quarrying Open pit mine that is used to harvest Granite Marble Sand
Gravel
Crushed rock (aggregates)
Clay
Gypsum
Talc
Granite quarry in Elberton, GA
LaFarge Granite Quarry in Douglasville, GA
Small picture is talc quarry in France. For making talcum powder.

13. 3. Solar Evaporation Place sea water into shallow ponds
Water evaporates and leaves crystallized salt behind
30% of world’s salt produced this way
Used largely in developing countries
Salt evaporation ponds in San Francisco Bay. The beautiful colors are a result of harmless bacteria and brine shrimp that live among the salt. The colors vary depending on the “age” of the pond.

14. C. What is placer mining? Rock with minerals weathers & disintegrates
Minerals carried by water in streams
As streams bend, the water slows, minerals fall out of slower water and accumulate as placer deposits
Can also occur along coastline where waves keep minerals from moving out to sea.
Use dredging to remove minerals
Bucket system that scoops sediment with minerals from bottom of body of water.
Minerals are separated from sediment
Scoop placer deposits in bucket, deposit on barge, barge takes to refinery for separation.

15. How is mineral removed from ore?
Smelting
Crushed ore heated to high temps.
Impurities are trapped by a material called flux & create slag that forms a layer on top of the melted metal which is easily removed (but toxic)
Purified molten metal falls to the bottom of the furnace and is harvested.
Heap Leaching
Using chemicals to dissolve mineral from ore
Ex: cyanide used to remove gold
Ex: sulfuric acid used to remove copper
Copper can be extracted thru smelting (top) OR thru heap leaching (bottom).