Mineral Exploitation

• Lasky's principle states that as the purity of a mineral decreases, the amount of the mineral present increases exponentially.
• The major problems with future mineral supplies is the need to develop methods to exploit low-grade deposits so they can be considered economically-viable.
• Mining companies have to plan years ahead because it takes a long time to prepare a mine before any of the mineral can be extracted. This includes gaining detailed information on the mineral that's to be mined, however these methods are expensive. Therefore, deposits that won't be exploited in the near future may be investigated with cheaper methods that provide less detailed information, whilst more expensive and thorough exploratory investigations would be carried out nearer the time of exploration.
• A stock includes all of the material that exists in the lithosphere that can be exploited now, in the future, or never.
• A resource is all the material that can be exploited now or in the future with realistic increases in prices or improvement in technology. For example, deep, low-grade ores in protected locations or in difficult chemical forms could become viable in the future.
• A reserve is the amount of material that can be extracted now with current economic conditions and existing technology. The size of reserves can change if economic or technological conditions change.
• Inferred reserves are when the presence of the mineral can be predicted from knowledge of the geological structures present but not enough is known to estimate the amount that is economically-viable to be extracted.
• Probable reserves are when sufficient information about the deposit is known, so the amount of mineral that can be economically extracted can be estimated with enough accuracy that further exploration is justifiable.
• Proven reserves are when sufficient exploration has been carried out, including trial drilling, to accurately estimate the amount of the mineral that is economically-viable to be able to extract.
• Even if the amount of a material that exists may be greater than could ever be needed, there are other factors that may limit the viability of exploitation: the absence of required technology to exploit the deposits; financial costs of exploration may be too great; environmental impact may be unacceptable.
• Remote sensing involves any technique that gives information without taking direct samples. It can be done at different distances from the deposits, collecting data on a range of scales e.g satellite surveys or ground-based surveys.
• Large-scale surveys may be more expensive than remote sensing, but are often cost-effective by providing a lot of information at a relatively low cost per unit area that is surveyed.
• IR spectroscopy is used to identify minerals based off of the infrared radiation they emit at different wavelengths.
• Gravimetry identify different minerals using gravimeters, which detect variations in gravity caused by variations in density and mass - igneous rocks are usually more dense than others.
• Magnetometry identifies different minerals using magnetometers detect rocks that are more magnetic such as magnetite and the ores of tungsten and cobalt.
• Seismic surveys identify different minerals by using sound waves produced by controlled explosions or seismic vibrators on the surface. The echoes can give information about the depth, density and shape of rock strata.
• Resistivity is the measurement of the difficulty with electricity passes through a material. Sedimentary rocks have lower resistivity than igneous rocks as they have a higher water content.
• Trial drilling produces samples of the rocks undergrounds, however is the most expensive exploratory technique.
• Chemical analysis identifies different minerals by using lab tests to confirm the chemical composition and purity of the minerals in rock samples.
• One factor that affects mining viability is ore purity as it affects the financial costs and environmental impacts of exploitation. If the ore grade is low: more rock will be mined; more spoil (waste) will be produced; more pollution will be generated; more energy will be needed.
• One factor that affects mining viability is the chemical form of the mineral as it affects the ease of chemical extraction of the metal e.g aluminium can be easily extracted from bauxite but not from clay, so aluminium is extracted from bauxite even though clay is more abundant.
• One factor that affects mining viability is associated geological features. A hard overburden increases costs to remove them, and a loose overburden increase landslide risks, so precautions (gentler slope of the mine) may cause the area of the mine to increase. High precipitation or impermeable rocks increase the drainage costs. As the depth of the mine increases, so do the costs; waste produced also rises as the depth increases as the sides of the mine can't be vertical due to risk of collapse, which also increases the amount of water which runs into the mine, increasing pumping costs.
• One factors that affects mining viability is economics as cut-off ore grades affect the grade of ore that can be economically-viable to be exploited; transport costs increase with distance from the mine to the market; market prices rise and fall with the demand and sale value of minerals, which control the economic-viability of the mineral deposit.