fundamentals of mining

8/9/2019 Fundamentals of Mining

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Fundamentals of Mining


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This lecture will help you understand:

• Mineral resources and their contributions to society

• Mining methods• Social and environmental impacts of mining

• Sustainable use of mineral resources


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Minerals and mining

• We extract raw minerals from beneath our planet’s surface

– Turn them into products we use everyday• Rock and resources from the lithosphere contribute to our

economies and lives

• Rock = a solid aggregation of minerals

• Mineral = a naturally occurring solid chemical element orinorganic compound

– t has a crystal structure! specific chemical composition!and distinct physical properties

Minerals are nonrenewable, so we need to be aware of their finite and decreasing

supplies


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Minerals are everywhere in our products


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We obtain minerals by mining

• We obtain minerals through the process of mining

• "ining = in the broad sense! it is the extraction of anyresource that is nonrenewable

– We mine minerals! fossil fuels! and groundwater

• Mining = in relation to minerals! it is the systematic removalof rock! soil! or other material to remove the minerals ofeconomic interest

• #ecause minerals occur in low concentrations! concentrated

sources must be found before mining


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We extract minerals from ores

• Metal = an element that is lustrous! opa$ue! and malleableand can conduct heat and electricity

• re = a mineral or grouping of minerals from which weextract metals

• %conomically valuable metals include copper! iron! lead!gold! aluminum

Tantalite ore is mined, processed into tantalum, and used in electronic

devices


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We process metals after mining ore

• "ost minerals must be processed after mining• &fter mining the ore! rock is crushed and the metals are

isolated by chemical or physical means

– The material is processed to purify the metal

• Alloy = a metal is mixed! melted! or fused with another metalor nonmetal substance

– 'teel is an alloy of iron and carbon

• Smelting = heating ore beyond its melting point then

combining it with other metals or chemicals


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Steps in btaining Mineral !ommodities

• "rospecting# finding places where ores occur • Mine exploration $ development# learn whether ore can

be extracted economically• Mining# extract ore from ground

• %eneficiation# separate ore minerals from other minedrock• Smelting $ refining# extract pure mineral from ore mineral

(get the good stuff out of waste rock)• Transportation# carry mineral to market

• Marketing $ sales# find buyers * sell the mineral


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Conversionto product

Surfacemining

Meltingmetal

Metal ore Separationof ore fromgangue

Smelting Discardingof product

Recycling

&ife !ycle of a Mineral Resource


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'xtraction process depend on shape(

position and value of ore body

• 'urface "ining (+heap! 'afe for miners! ,arge amount ofenvironmental destruction)

– -pen .it

– 'trip "ining• /nderground "ine (%xpensive! 0a1ardous for miners! ,ess

environmental damage)

• 2issolution3 potash! uranium!

• n situ mobili1ation3 oil shale• 0eap ,each


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pen "it Mining

%ingham !anyon !u Mine

) km in diameter * km in

depth( at its +enith ),,,,,tons of rock per day

'kati -iamond Mine

a4 -verlaying material is

removed using largee$uipment

b4 +reates pits that arehundreds of meters wide andhundreds of meters deep4

c4 The amount of waste rock tobe removed to providereasonable gradient fortrucks4

d4 -nly efficient for large ore

bodies close to the surfacee4 +an be useful for dumpingmine waste at closure


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Strip Mining

a4 ,ike open pit but notas deep of a pit

b4 'ame environmentaldamage

c4 5ery efficient for highlevel flat lying orebodies

d4 -verburden and topsoil can be replacedminimi1ingenvironmentaldamage


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.nderground Mining

a4 5ery expensive and the mostdangerous of the threemethods! but has the leastimpact environmentally on theearth’s surface4

b4 /nderground mining is donewhen the rocks! minerals! or

gemstones are too farunderground to get out withsurface mining4

c4 %ntry into underground minesis by vertical shafts! or by asloping tunnel4

d4 'ome types of /6 "ining –Room and .illar! +ut and 7ill!,ong wall (coal)! 'hrinkage'toping! #lock +aving etc4


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2issolution3 potash! uraniumn situ mobili1ation3 sulfur! oil shale

NaCl or KCldissolved inwater

Acid insitu leach ofmetallicore

Hot water or steamused to mobilize

sulfur or oil


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/eap &each

Landusky, Montana, CN Heap Leach old Mine !"#"$!""%


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Mining and environmental issues

• 6aping holes in ground (old open pit mines)

• &ccidental draining of rivers and lakes• 2isruption of ground water flow patterns• .iles of gangue8 mine tailings (mining waste)• ,oss of topsoil in strip8mined regions• 'poil banks are where holes were filled in with waste8 cheap * easy8

susceptible to erosion! chemical weathering! causes high sediment runoff in

watersheds4 'teep slopes are slow to re8vegetate (succession happensslowly8 no topsoil)• +ontamination of soil or water from heavy metals (e4g4 arsenic! mercury) in

mine tailings4• +ontamination from sulfuric acid (09'-:) produced through weathering of

iron sulfide (7e'9! pyrite) in tailings4 – :7e'9 ; 09'-:

• Water leaking into mine shafts! washes dissolved metals * toxic materialinto water sources4

• ,oss of biodiversity in the area• &bandoned mines can still pose safety ha1ards such as deadly gases


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Minimi+ing the impact:

- f mining will cause $uality deterioration of either surface water orgroundwater! remedial and treatment measures must be developedto meet discharge standards4

- The mine plan must include all the technical measures necessaryto handle all the environmental problems from initial data gatheringto the mine closure and reclamation of the disturbed surface area4

Mining and environmental issues


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/ow can we conserve geologic

resources0

• Recycling

– 'aves energy

• Recycling aluminum cans re$uires


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T/213 4.

fundamentals of mining

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