6.6 Mining (minerals as a resource (a mineral is a naturally ocurring…
minerals as a resource
a mineral is a naturally ocurring chemical element or inorganic compund that exists as a solid with a regularly repeating internal arrangements of its atoms or ions.
a mineral resource is a concentration of one or more minerals in earth's crust that we can extract and process into raw materials and useful products at an affordable cost.
minerals are a non renewable resource
rocks consists of one or more minerals. some rocks such as limestone and quartzite contain only one mineral
an ore is a rock that contains a large concentration of a mineral- often a metal- to make it profitable for mining and processing.
high grade ore= high concentration of mineral
low grade ore= low concentration of mineral
minerals: aluminum, iron, manganese, cobalt, chromium, copper, gold, diamond
rocks: silicon dioxide, basalt, granite, limestone, marble, phosphate
how long will mineral supplies last?
we have never run out of a non renewable resource, but a mineral becomes economically depleted when it costs more than its worth to fund, extract, transport and process the remaining deposits
mineral reserves are the identified deposits from which we can extract the mineral profitably at current prices
economic depletion: depletion time is the time it takes to use up a certain proportion, usually 80%, of the reserves of a mineral at a given rate of use. once a mineral is economically depleted there are five choices: waste less, use less, recycle, reuse existing supplies, find a substitute, do without
minerals are not deposited evenly across the earth. the US, canada, russia, south africa, and australia supply most of the non renewable mineral resources that modern societies use
rare earth elements: most rare elements are not actually rare but they are hard to find in large concentrations
types of mining and their impact
surface mining: mineral deposits close to surface are removed by clearing away vegetation, soil, and rock overlying a mineral deposit area. surface mining is used to extract about 90
5 of the nonfuel mineral resources and 60% of the coal used in the US
strip mining: used to extract mineral deposits that lie in large horizontal beds close to the earth's surface. area strip mining: used on flat terrain. contour strip mining: used on hilly or mountainous terrain, mainly for coal.
mountaintop removal: explosives are used to remove the top of a mountain and expose seams of coal. this destroys forests, buries mountain streams, increases the risk of flooding.
sub surface mining: used to remove metal ores and coal that are too deep to be extracted by surface. subsurface mining disturbs less than 1/10 as much land as surface mining and produces less waste material
surface mining pros: cheaper, faster, safer for miners
cons: destroys huge areas, blocks river valley, toxic runoff pollutes rivers, groundwater, gets into food chain
subsurface mining pros: less destructive, less waste material
cons: expensive, slow, higher risk to miners
environmental damage: solid waste= 75% of all solid waste in the US comes from mining.
water pollution= acid mine drainage. 40% of all watersheds in western US are contaminated by mines.
air pollution= 50% of US toxic are emissions come from mining
the lower the grade of ore, the bigger the environmental impact. every metal product has a life cycle that includes mining the mineral. processing it, manufacturing it, disposal or recycling of the product. this process uses large amounts of energy and water and produces pollution and waste
mining lower grade ores takes more money, energym water and other resources and it leads to more land disruption, mining waste and pollution
processing ore: 1. separating ore from waste material. 2. separating metal from ore: smelting or chemical solvents
sustainable mineral use
reduce: develop alternatives instead. human ingenuity is creating a materials revolution
reuse and recycle: recycling has a much lower environmental impact than that of mining and processing metals from ores