A2 Economic Deposits, Extraction and Processing Flashcards
Ore
the rock containing valuable metal(s) that is economic to mine.
Resource
a useful and valuable natural material.
Mineral resources
can be metallic and non- metallic or industrial minerals.
Reserves
the amount of the resource that can be extracted at a profit using existing technology.
Ore deposit
an accumulation of metal that may be economic to mine.
Average crustal abundance
describes the amount of metal in ‘average’ continental crust.
Concentration factor
the amount by which the metal is concentrated to make an ore deposit.
Ore mineral
a mineral containing valuable metal(s).
Gangue mineral
a low-value waste mineral.
Grade
refers to the concentration of valuable mineral within an ore.
Cut-off grade
the grade below which it is uneconomical to mine.
Secondary enrichment
occurs when metals are leached from within surface rocks and precipitated just below the water table.
Chemical weathering
the in situ breakdown of rocks at the Earth’s surface due to chemical reactions.
Leaching
where ions are dissolved from rocks and carried downwards in solution.
Gossan
an insoluble cap of iron oxides at the surface of a mineral vein.
Oxidising
describes oxygen-rich conditions, allowing elements to combine with oxygen to form oxides.
Reducing
describes oxygen-poor, anoxic conditions.
Enriched deposit
a zone of high-grade ore just below the water table, formed by secondary enrichment.
Porphyry
a large igneous intrusion with a porphyritic texture.
Dredging
where material is scraped or sucked from the river or sea bed.
Hydraulic mining
the use of high-pressure water jets to dislodge material.
Geophysical anomaly
a departure from the normal value and may be positive or negative.
Geochemical anomaly
a concentration of a metal above its normal background value.
Dispersion
occurs when small amounts of metals are spread out around the ore deposit by the surface processes of weathering, erosion and transport.
Catastrophic dilution
occurs where tributaries meet and water and sediment from other sources are added.
Geographical Information System (GIS)
a computer application used to store, view and analyse spatial information, especially maps.
Sustainability
using a resource so that it is not depleted or harmful to the environment, supporting a long-term balance in ecological and other systems.
Non-renewable resources
do not renew themselves at a sufficient rate for sustainable economic extraction within a human lifetime.
Open cast
extraction is mining from surface quarries.
Shafts
vertical openings to an underground mine.
Stope
the void left when the ore has been extracted from an underground mine.
Flotation tailings
the waste rock fragments which do not attach to bubbles in the froth flotation process.
Leachate
the liquid that drains or leaches from a landfill site.
Pollution plumes
are zones of contamination, usually into an aquifer or water source. This can be from various sources, including leachate from landfill sites.
Transuranic elements
have atomic numbers greater than 92, the atomic number of uranium. These are unstable and decay radioactively into daughter elements.
Carbon sequestration
a process where CO2 is removed from the atmosphere and held in an alternative form, either solid or liquid.
Open cast mining
also called open pit mining, surface mining technique, common technique, cheap, large volumes of material quickly, massive habitat destruction
Stope mining
vertical or diagonal shaft, horizontal stopes (voids) directly into the ore body. Sometimes require roof supports depending on rock strength. More specialized equipment required, ventilation, water pumping. Far less habitat destruction that open cast.
Longwall retreat mining
Ore body/coal seam exposed. A circular cutting tool, shearer, moves along the face. Ore material deposited onto a conveyer. Machinery and roof supports move forward towards the face. Area behind the supports is allowed to collapse.
Kriging technique
A geostatistical computer model that creates a 3D block model of the deposit based on probabilities
Downhole logging
Drilled borehole. Cameras and/or instruments collect geophysical data and samples for geochemical analysis.
Geophysical survey techniques
Gravimetry, Magnetic, Electromagnetic, Resistivity
Geochemical survey techniques
Stream sediments, Water, Soil, Vegetation
Life cycle of a mine - 5 steps
in situ leaching
heap leaching
froth flotation
Formation of acid mine drainage
Reducing AMD at source
AMD diversion
AMD active treatment
AMD passive treatment
Smelting of iron ore
