Mining

By Brandon, Daniel, Liam, and Reilly

Mineral Resources

• A mineral, by definition, is any naturally occuring, inorganic substance, often additionally characterized by an exact crystal structure.

• Elements that occur naturally are also considered minerals.

Ore• An ore is a type of rock that contains

minerals with important elements including metals. The ores are extracted through mining; these are then refined to extract the valuable element.

• The grade of the ore affects how valuable it is.

• Metal ores are generally oxides, sulfides, silicates, or “native” metals

• The process of ore formation is called ore genesis.

Ore Genesis

• Three components: source, transport, conduit, and trap

• Source - Metal must come from somewhere• Transport- Required to move the metal

bearing fluids or solid minerals into the right position

• Trapping - Required to concentrate the metal by physical, chemical or geological mechanism into a concentration which forms mineable ore.

Ores formed by magma

• Internal process• Integral physical phenomena and

chemical reactions• Plutonic or Volcanic rocks to magma• Fractional crystallization or liquation

Hydrothermal Processes• As magmas solidify, water and other gaseous

constituents tend to be concentrated in the decreasing amount of molten rock.

• These constituents boil off, penetrate the surrounding rock and condense to a hot, water-rich fluid.

• The tend to lose the metals they carry and form ore deposits when they encounter a favorable location.

Sedimentary Process

• Sedimentary processes form ore either through the selective removal of nonmetallic components or by concentration of metallic minerals.

• Rock at the earth's surface is subjected to weathering and leaching, the process that turns rock into soil

• Bauxite forms in the humid tropics from intense and prolonged weathering of aluminum-bearing rocks.

• The concentration of heavy metallic grains forms placer ores.

Manganese Nodules

• At the bottom of the ocean• 3,000 meters below the water.• You can buy it for $26 for a 1.25 inch

block• Ore from ocean can come from these

Non-Metallic Mineral Resources

• Mineral resources that do not contain metals; examples include building stone, gravel, sand, gypsum, phosphate, and salt.

Environmental Impacts of Mining

•Mining, in all of its forms, causes damage to the land that is mined. Trees are stripped to allow for mining and as a result the land erodes into a barren wasteland.

•Land subsidence occurs when large amounts of ground water have been withdrawn from certain types of rocks, such as fine-grained sediments. The rock compacts because the water is partly responsible for holding the ground up. When the water is withdrawn, the rocks falls in on itself. Mining causes land subsidence by removing subsurface water to allow for mining to occur.

• All mining causes waste to be produced. In many cases, this waste is toxic and detrimental to the environment. Mine operators, looking for a cheap way to dispose of this waste, can dump it into the surrounding area through lakes, ditches, etc. This waste can poison the landscape and ultimately affect the humans living in the area.

• Acid mine drainage is the outflow of acidic water that is produced from mines, usually abandoned ones. This water can contaminate the surrounding environment and lead to the decline of organic life.

• Acid shock occurs when a body of water drastically changes its level of pH over the course of a year. If the pH level is too high, the water may become permanently changed. A high level of pH in the water can lead to the elimination of some species in the area and can alter the environment.

• Mining often releases detritus in the air, and this detritus can be seriously harmful to humans. The people in the area surrounding the mine, not only the miners, can be affected by this air pollution and develop serious medical problems.

• Wildlife can be severely harmed by mining. The noise from a mine can alter the habits of certain animals. In addition, mining can disrupt the habitats of animals and plants. The toxins often released through mining can cause an environment to become virtually uninhabitable.

• Bioremediation is a process through which microorganisms, green plants, fungi, or their enzymes return the natural environment altered by contaminants to its original condition. It can help to rejuvenate many sites that have been decimated by mining and render them livable once more.

Removal of Resources

Needed to locate and map deposits of mineral ores, test them for richness, and then drill to set charges, blast

and send in men to remove the material

Gangue is removed from coal by settling velocity separation which removes the alcohol content

Tailings is a waste product that consists of ground rock. Tailings are generally stored on the surface in retaining structures but can also be stored underground in mined out voids by a process commonly referred to as backfill.

• Surface mining is a type of mining where soil and rock overlying the mineral deposit are removed.

• Overburden is the term used in mining and archaeology to describe material that lies above the area of economic or scientific interest

• Spoils is the waste material brought up during the course of an excavation or a dredging or mining operation.

Open-Pit Mining

• A method of extracting rock or minerals from the earth by their removal from an open pit or borrow

• Dredging is an excavation activity or operation usually carried out at least partly underwater, in shallow seas or fresh water areas with the purpose of gathering up bottom sediments and disposing of them at a different location.

• Strip Mining is a method of mining especially for coal, by laying a mineral deposit near the surface of the earth, instead of by sinking a shaft

• Spoil banks are the areas of accumulation of overburden

• High wall mining is a method of coal mining in which a continuous mining machine is driven under remote control into the seam exposed by previous open cut operations.

• Mountaintop removal mining is a form of surface mining that involves the mining of the summit or summit ridge of a mountain.

•  Sub-surface mining consists of digging tunnels or shafts into the earth to reach buried ore deposits

• Additional sub-surface mining methods include Hard rock mining which is mining of hard materials, bore hole mining, drift and fill mining, long hole slope mining, sub level caving and block caving

• Borehole Mining is a remote operated method of extracting mineral resources through boreholes by means of high pressure water jets.

• Identified Resources are resources whose location, grade, quality, and quantity are known or well estimated from specific geologic evidence.

• Unidentified Resources are resources that are unknown or lack the specific geologic evidence to determine the location, grade, quality, or quantity.

• Reserves are a portion from which a usable mineral or energy commodity can be economically and legally extracted.

• Minerals are found through discovery of the ore body, which is carried out through prospecting or exploring to find them, then define the extent, location, and value of the ore body.

• Minerals are found all over the world in rocks and within the earth. Under the right circumstances and the knowledge of minerals, an experienced explorer can find them somewhat easily, especially in hotspots.

• Depletion is defined as the act of emptying, reducing, or exhausting the natural resources (ores).

• Economic depletion is defined as the reduction in the value of a mineral deposit as the mineral reserves.

• Depletion Time refers to the time frame in which 80% of the mineral or resource is predicted to be depleted; the other 20% being extremely expensive. For example, copper and iron found in Earth’s crust would last us 120 million years and 2.5 billion years respectively.

• When the depletion time comes near, economic depletion could become a problem quickly.

Reserves to Production Ratio• (The total amount of the resource) / (the

amount used annually). The R/P Ratio is used by companies and government agencies to predict the future availability of a resource to determine project life, future income, employment, and to determine whether more exploration must be undertaken to ensure continued supply.

Ore Grade• The grade or concentration of the ore

will directly affect the price.• The grade can change over time.• Knowing the ore grade helps optimize

the amount of the mineral that can be extracted.

SMCRA• The Surface Mining Control and

Reclamation Act of 1977 is the primary federal law that regulates the environmental effects of coal mining.

• Specifically, the act regulates active coal mines and reclaims abandoned coal mines.

• This act has focused on more efficient ways to extract resources.

General Mining Act of 1872• A U.S federal law that authorizes and

governs prospecting and mining for economic minerals, such as gold, platinum, and silver, on federal public lands. This law gives all citizens over 18 to rightfully claim minerals and natural resources.

• Formed by prospectors in California during the gold rush.