Extraction Methods for Rocks, Minerals & Fossil Fuels

Strip Mining

• Many of the minerals people want to extract are under a layer of rocks and soil called the overburden. If the layer of overburden is not too deep, then strip mining is a practical way to excavate. If the terrain is fairly level, then area stripping is used to get deposits from a large area. If the terrain is hilly, then contour stripping is used. When the contour mining is done, it sometimes leaves a terraced appearance to the hillside.

Open Pit Mining

• Open pit mining consists of taking the minerals from a large pit in the ground. A quarry is one type of open pit mine. Granite can come from a quarry to be used on counter tops and other domestic applications. This type of mining is cost efficient if the minerals or rocks are close to the surface. It is also an option if underground mining is not feasible.

Mountaintop Mining

• This type of surface mining literally takes off the top of a mountain to get to the needed ore. It is common in coal mining and sometimes referred to as Mountaintop Removal Mining or MTR. Explosives are detonated to remove the overburden and let equipment reach the seam of ore that is several hundred feet below the surface. Because this changes the topography of the terrain, this is a controversial method of extraction. Those in favor say the extra land is dumped into valleys that provide flat land for other uses. Opponents say there is damage to the environment and ecosystems by putting more minerals into rivers and streams that affect wildlife. Blasting also can expel minerals, such as sulfer, into the air that cause air pollution.

Underground Mining

• Underground mining is done by digging shafts or tunnels to reach the deposits of ore. Drift mining uses access tunnels that are horizontal, while slope mining shafts are diagonal. Shaft mining uses vertical shafts. The mining methods include room, pillar and longwall. In room and pillar mining, rooms are cut out. The rooms feature pillars made of leftover ore to support the roof. The ore is placed into shuttles, then placed on a conveyor belt that takes it to the surface. The disadvantage to this type of mining is it leaves a lot of ore in the pillars, so sometimes when the job is done, the pillars will be mined as well. Longwall mining uses hydraulic-powered roof supports while the ore is extracted and placed on conveyor belts. These supports are only temporary until mining is done. This way is more efficient, but the machinery is more expensive.

Drilling for Oil/Fossil Fuels

• Geologists use different types of testing equipment to find deposits of oil under the ground. The equipment includes seismic surveys that use shock waves, gravity meters, sniffers and magnetometers. When oil is found, the drilling rig is set up and drilling commences. Some of the things needed are water, access roads, and reserve pit for the waste which is mud and rocks. When the oil is found, it is then pumped out of the ground and sent to a refinery.