Types of Subsurface Mining

advertisement

Minerals and

Mining

Minerals

• Concentration of naturally occurring elements in/on

Earth.

• Formed over millions of yrs

 non-renewable resource.

What We Mine?!?

• Metallic minerals: Iron, Copper, Aluminum

• Non-metallic minerals: salt, clay, sand

• Energy minerals: coal, oil, uranium

Crushed Iron

Sodium Chloride

Crystal

“Dur”rty Coal

Ore

• Rock that has metallic mineral.

• Usable stuff is the mineral

• Non-usable is called

gangue

 landfill

Gold

Gangue

Smelter s

• Used to remove mineral from gangue in an ore

 major polluters (Runescape!).

Bauxite

Most Important Aluminum Ore

Oxygen: The Most Abundant

Element in the Earth’s Crust

Finding Mineral

Deposits

• Use aerial photos and satellite images to see rock formations.

Finding Mineral

Deposits

• Use planes w/ Geiger meter

(uranium) or magnetometer (iron)

Geiger

Meter…Only $460!

Magnetometer…

Only $700!

Finding Mineral

Deposits

• Drilling a deep well and extracting ore samples.

Exploration Drilling

Surface

Mining

• Minerals must be shallowly deposited.

• Removed rock and soil is called

overburden

or

spoil

.

Types of Surface Mining

Open Pit Mining

• Dig hole and remove ores

• Fe, Cu, and Sand

Types of Surface

Mining

Dredging (Sand)

• Draglines scrape up underwater mineral deposits

Types of Surface

Mining

Area Strip Mining

• Cut new strips away; spoil placed on side, mineral taken out.

Types of Surface

Mining

Mountaintop Removal

• Use TNT, huge shovels, and large machines to remove top of a mtn and expose coal underneath.

Case Study Gold: Cyanide

Heap Leaching

• Cyanide sprayed on low grade gold ore

Heap

in a giant heap

(pile).

• Gold flows down w/ cyanide and is collected at bottom of heap.

Case Study Gold: Cyanide

Heap Leaching

• Toxic to birds and mammals.

• Leach ponds can overflow

H

2

O pollution

• Leaky liners?

Leach Liner

Subsurface

Mining

• Used to remove minerals deep in Earth’s surface.

• Less env.

Impact

Types of Subsurface Mining

Room and

Pillar

• Machines are used to cut out minerals and are placed on a shuttle car.

Scraper

Types of Subsurface Mining

Longwall Coal

Mining

• Moveable steel props support cave while machinery cut off coal onto a conveyor belt.

Environmental

Damage

• Collapse/subsidence of land from subsurface mines.

• Causes houses to tilt, sewer lines crack, gas mains break.

Environmental

Damage

• Wind/water carry away [by erosion] toxic mining waste.

• Goes in food webs and watersheds.

Environmental

Damage

Habitat Loss!!

My

Home!!!

Environmental

Damage

• Transportation of minerals

 warming, lung probs. global

Environmental

Damage

Acid mine drainage

• Bacteria eat FeS in spoil 

H

2

SO

4

 create runs off into streams

Surface Mining

Reclamation and Control

Act

• Mining ops must reclaim area after land has been used and abused.

• Must put aside $$$ to reclaim before mining op’s begin.

• States oversee Act.

• Land put back, trees grow, no toxic runoff!

Download
Study collections