Mining & Mineral Resources
Chapter 16, Section 2: Mineral Exploration &
Mining
Standards: SEV4a, b, e
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
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
3 Types of Mining
A. Subsurface mining
Surface mining
C. Placer mining
B.
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
2. Longwall mining
3. Solution mining
1.
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.
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
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.
B. What is surface mining?
 Used when ore deposits are
located close to Earth’s
surface
 3 types
Open Pit Mining
2. Quarrying
3. Solar Evaporation
1.
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.
Bottom picture: Open pit gold mine with
heap leaching cyanide ponds down below.
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.
2. Quarrying
 Open pit mine that is used
to harvest
 Granite
 Marble
 Sand
Granite quarry in Elberton, GA
 Gravel
 Crushed rock (aggregates)
 Clay
 Gypsum
 Talc
LaFarge
Granite
Quarry in
Douglasville,
GA
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.
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.
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 through smelting (top)
OR through heap leaching (bottom).