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Open Pit Mining

www.MineralsEd.ca

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Openpitminingisusedtoextractoreinrockbodiesthatareatorclosetothesurfaceof

theEarth. Largescaleequipmentdrills,shovels,andtrucksareusedtomakeoperations

efficient

and

economical.

When

they

move

in,

the

ore

is

dug

up

and

sent

to

a

mill

for

processingandreclamationproceduresareinitiated.

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1 Inanopenpitoperationa

rotarydrillisusedtodrill

holesthatare~30cmin

diameterand~15mdeep.

Theholes

are

commonly

filledwithANFO(short

forammoniumnitratefuel

oil)explosives.

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2 Theblastpattern drillholelocationandspacingandlocationdependsonthe

type

of

rock

mined

and

overall

mine

plan.

The

depth

of

the

hole

will

determine

theheightofthe benchinthepit,generally1213m.

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3 Blasting!Explosivesinthedrillholearedetonated,breakinguptherockintosmaller

piecesthatcanbetransportedforfurtherprocessing.Dependingonthesizeofthe

mine,availability

of

equipment,

and

capacity

of

the

mill,

blasting

may

be

scheduled

everydayorevery23days.

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4 Largeelectricorhydraulicshovelsscoopupblastedrockandloadintohaultrucks.

Todaytrucks

are

very

large,

carrying

80

200+

tonnes per

load.

It

may

take

only

23shovelsfulltoloadahaultruck,thenanemptyoneisreadytotake

itsplace.

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5

Haultrucks

loaded

with

ore

transport

it

to

aprimary

crusher

which

crushes

the

oretopieceslessthan30cm.

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6Therearedifferentstylesofprimarycrushers(e.g.jaw,gyratory,cone)

which

all

use

heavy

steel

parts

that

move

together

to

break

up

the

rock.

Crushedore mustbehauledbytruckorconveyedtoamillforfurther

processing.

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7

Haultrucks

also

transport

waste

rock

from

ablast

out

of

the

pit

to

a

wasterockdump.

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8 Thelocationofwasterockdumpsisdeterminedintheoriginalminedesign.They

aregenerally

located

on

the

margins

of

an

active

pit,

but

later

on

can

be

situated

in

aninactivepit,asshownhere.

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9 Wasterockdumpsarebuiltuptospecificdimensions.Whenreachedthatsizeand

shape,they

must

be

reclaimed

(hyperlink

to

Mine

site

reclamation),

re

sloped

ifnecessaryandrevegetated.