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55 Cards in this Set
- Front
- Back
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What is an Ore?
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Any rock that is enriched enough in a particular element or mineral to be mined.
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What production costs control the value of the ore?
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digging up rocks, marketing and distribution and waste disposal
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a mineral deposits increase in depth, the cost of extracting them usually what?
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increases
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The gold concentration at a hypothetical mine is 10 gold particles for ever 1,000,000 sediment particles. How can this correctly be written?
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10 ppm
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What is the ultimate control on the definition of “enriched”
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Cost of extraction
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Factor of Enrichment
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grade/average crustal concentration
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what percent of Gold (AU) is waste?
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99.999%
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sedimentary - placer deposits
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Heavy minerals grains require high
velocity water to carry them downstream Grains settle where water velocity drops placer gold placer diamonds |
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Igneous processes
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Settling of dense (metal rich) mineral crystals out of a
magma chamber Enriched layers accumulate in bands in chamber |
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Hydrothermal Processes
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“hot water”Magma rising into the shallow crust heats water in the surrounding rocks
Hot water is also released from magma Valuable elements are dissolved in the hot water which flows through adjoining, cooler rocks |
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igneous processing
“enriching the host rock” |
fluids cool down and new minerals and elements are deposited.
near ground water or seawater |
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Hydrothermal Veins
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mineral-filled fractures
formed by cooling hydrothermal fluids |
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Divergent boundaries often deposit
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lead (Pb)
zinc (Zn) copper (Cu) mid-ocean ridges |
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Convergent boundaries often
deposit |
gold (Au)
copper (Cu) other metals |
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Heated seawater dissolves elements from the crust
Deposits them around submarine hot springs (black smokers) at where? |
at the sea floor.
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inexpensive geophysical prospecting techniques
to measure unique mineral properties |
radioactivity
high density magnetism Exploration and Mining -Prospecting stage - measuring local variations in radioactivity - gravity - magnetic field |
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anomalies
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disturbances
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Geochemical Prospecting
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Analyze stream sediments for
gold concentration Gold ore weathers from an outcrop and is dispersed into stream sediments |
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Exploration wells
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most expensive
require permission private lease from landowner and/or gov’t exploration permits |
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Assay
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chemical analysis to
determine the amount of valuable elements present |
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Predicted tonnage of the deposit =
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amount of ore present
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Mine Operation Plan
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long-term plan for entire lifespan of deposit
Covers all phases of development, exploitation, and decommissioning |
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Surface Mining
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either strip mining or open pit
- generally cheapest mining option - used whenever deposit is close to the surface |
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Underground Mining
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uses series of shafts and tunnels to access deeply buried
deposits - more expensive; used mainly for high value commodities |
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what percent of US production uses strip mining?
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85% US production uses this mining.
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Common minimum length of mine operation
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10 years
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open pit mining
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Most common type of surface
mining Benches - shallow ledges with stepped sides. Benches are blasted with explosives and the debris is loaded into large trucks Ore is taken to the processing plant, where metals/minerals are extracted |
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Heap Leaching
problem? |
Crushed ore is spread on plastic mats and sprayed with an acid solution
Acid dissolves the metal from the rock Ex: Au (gold) Low concentration ores are soaked with the Sodium Cyanide solution Heap leaching operations create environmental hazards because the cyanide solutions can leak |
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heap leaching use?
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Used for shallowly buried and flat lying ores
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Overburden
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soil and rock overlying the deposit
stripped away to expose the ore Leaves unsightly scars on the landscape Federal and state regulations now require mines to restore mines after production grade land and replant the vegetation |
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Dredging
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Mining loose sand and gravel in rivers for gold and other heavy minerals (placers)
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Dredge
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floating barge that has a conveyer belt with buckets
Sand and gravel are scooped up and processed on the barge Waste material is dumped behind Dredge moves slowly upstream, digging a trench in front and filling it up behind |
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dredging problem?
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Destroys river bottom
(plant/animal habitat) Releases large amounts of sediment in the water Harms all users of water downstream (plants, animals, people) |
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Room and Pillar Method -
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Some of the deposit is left as
pillars to support the overlying rock Allows further mining operations |
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Dump piles aka
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tailings
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Separation
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use of properties of minerals to separate them from waste material (gangue)
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how are they separated?
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density - cyclone/compressed air
wettability - attract/repulsion from oil (froth floation) magnetism -- separate magnetic and non-magnetic minerals - |
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Froth Flotation
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Water-oil mixture circulates
with crushed ore in tank |
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Smelting
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heating/melting/burning the concentrate, produces a pure metal
- metal can be refined by chemical processes |
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Three general aspects of mineral resource development:
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1) ownership or control of mineral resources
2) conditions for conducting exploration, development and mining 3) mineral taxation |
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Regalian Law
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(a.k.a. civil law)National government owns all mineral resources
Authorize exploration, development and mining by granting concessions (contract and lease) Discretion over granting permits Tax (royalties) mineral production |
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Common law
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Private ownership of land and the rights to extract minerals from that land
Mineral or land rights can be sold or leased by the owner together or separately |
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Communist System
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The “state” owns all mineral rights and controls all phases of mineral development Most former communist countries have slowly
return to privatization of land and resources |
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U.S. mining law
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complex mix of regalian and common law traditions
Metallic minerals - Common law tradition Regalian law leasing system (for non-metallic and energy resources) Established free and open access for metallic mineral exploration on public by a claims system Mining Law |
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General Mining Law of 1872
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Established free and open access for metallic mineral exploration on public by a claims
system Claim problems during the California Gold Rush of 1849 Settling the West Job opportunities for soldiers after the Civil War New federal tax revenue The federal government can no longer collect a royalty (mineral production tax) Individuals can claim and ultimately own federal (public) land |
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Patent
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acquiring full title (ownership) for both surface and subsurface resources
$500 fee and evidence of a valuable deposit present with its boundaries mapped |
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Apex Rule
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person who claims the highest surface outcrop of a lode has a right to
mine the entire deposit, even if it passes beneath a neighboring claim at depth A.K.A. - Rule of Extra-lateral Rights the right to mine the lateral extent of the lode outside of the original claim ( doesn't apply to placer claims) only lodes (vein). |
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Mineral Leasing Act of 1920
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Governs exploration and exploitation of energy resources (FOSSIL FUELS) and industrial mineral
resources on federal lands Passed at the end of WW I to generate revenue and encourage oil and coal exploration |
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Regalian Law
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Established leasing system for blocks of public lands containing energy resources
both competitively and non-competitively Companies pay royalties on the resulting resource production Land title remains with the federal government 2-6 year prospecting permits in areas of unknown resource potential |
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Reserve areas
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Areas with known resource potential
Offered during periodic lease sales |
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Common Varieties Act of 1955
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Covers common, non-metallic deposits
sand gravel stone cinders pumice People or companies purchase (not claim or lease) the right to mine these minerals on federal lands |
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State and Local Government Lands follow what laws?
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most by regalian
Some states (like California) do allow claim-staking of metallic deposits |
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The California Desert
Protection Act of 1994 |
Removed vast portions of CA
deserts from mineral and energy exploration and development Important resources are known or suspected to be present in the withdrawn lands Voting public approved the law but it has long-term consequences for domestic mineral and energy industries |
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withdrawing land from development
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200 million acres of federal lands are withdrawn National parks - 1872 yellowstone national park created. --all parks included by 1976 no claims or leasing mineral and energy rights.
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mineral leasing act of 1920 established the system used by the US gov to develop what typeo f economic resource?
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fossil fuels
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