Cut & Fill Stoping

8/10/2019 Cut & Fill Stoping

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In cut and fll mining the ore is excavated bydrilling and blasting in horizontal slices, starting

rom the bottom o a stope and advancing upwardsas in shrinkage stoping. A slice has a thickness onot more than 3m. The broken ore is loaded andcompletely removed rom the stope. hen oneslice o ore has been excavated, the corresponding

volume is flled with waste material upto within !"#m o the back beore the next slice is attacked. Theflling serves both as support or the walls and as a$oor when the next slice above is mined.

Cut and fll Mining Description


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Cut and fll Mining

Description (Contd.) The flling material may be waste rock excavated during

development, crushed and distributed mechanically over thestope area. In modern cut and fll, however, the hydraulic fllingmethod is a normal practice. The flling material may be milltailings rom the ore dressing plant, sand, crushed rock, boilerplant ash or slag o smelter plants. The mill tailings should be ocoarse size as fne tailings , available rom the mills where theore needs to be crushed very fne or treatment, are easilywashed away by the $owing water. The flling material mixed

with water, is transported into the mine and distributed throughpipelines. hen the water is drained o% a solid consolidated fllwith a smooth surace is produced. &ometimes the material inthe last pour in a fll is mixed with cement to provide a hardworking surace.


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Cut and fll Mining

Applicability 'ut and fll mining can be used with steeply dipping as

well as large deposits with irregular outline can beworked. It is thus a versatile method.

The flling operations are easier with steeper deposits.An important advantage o this method is the $exibilityand high degree o extraction.

'ompared to sublevel stoping and high shrinkagestoping, cut and fll method o%ers advantage oselectivity. (igh grade ore can be extracted leaving thelow grade ore behind in the fll.

)ilution o ore is very little. It is thereore oten used orores with irregular boundaries, ores o rather high valueand unstable wall rocks.

This method is preerred to other mining methods whereground surace is to be prevented rom subsidence.


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Cut and fll Mining

PreparationThe ore block may be prepared in the same way asor shrinkage stoping but the chute raises are notunneled out at the top. The preparations o *

(aulage drit along the ore body at the lower mainlevel.

+ndercut o the stope, usually "- m above thehaulage drit.

&hort raises or manways and ore passes romhaulage drit to undercut.

/aise rom undercut to the level above ortransport o material and or ventilation.


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Cut and fll Mining

Preparation (Contd.) 0rovision o su1cient water and flling material and

arrangement or their storage and transport.

Ade2uate pumping capacity underground to pump out

water over$owing rom the flled stope.The ore slice in cut and fll can be drilled in twodi%erent ways, with horizontal shot holes or withupward, vertical holes. ith the later method a certainheadroom is re2uired between the back and the fll

surace, usually !."#m. Ater blasting and removal othe ore, this distance is increased to 3"4m, whichmeans that a comparatively competent ore andhanging wall are re2uired.


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5igure !.-3


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Cut and fll Mining

Preparation (Contd.)5or the drilling, light rock drills on simple wagons are otenused. 6ore mechanised drill rigs can also be used. Anadvantage o the up"hole drilling method is that large sectionso the root can be drilled without interruptions and large

rounds can be blasted.

Ater every !.7"!.m slice o ore has been stripped rom theback, a series o specially cut planks o wood are built upabove each chute to within about !.m o the back. asteflling material is now placed in the stope between ad8acent

timbered chutes and between the end chutes and thebarricades.

As the stope proceeds upwards, timbering and flling proceedon a cyclic basis. hen the crown pillar is reached, the stopeis completed and abandoned.


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5igure !.-4 in defnit


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Cut and fll Mining

Preparation (Contd.)'ut and fll mining has a very broad range oapplications, due to the $exibility, good recoveryand the possibility o mining under rather weak

rock conditions. The hydraulic fll has improved theeconomic and technical aspects o this method.

A characteristic o this method is that the cut andfll is a cyclic operation, ore production rom astope is discontinuous, as the mining has beinterrupted during the flling9 with hydraulic fll theflling period, however, is a compariaively short.


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Cut and fling Advantages +nlike in shrinkage stoping, ore is removed immediately

ater blasting. (ence no capital remain blocked up.There are no fre hazards and no oxidation problem.

It is a sae method. A large area is not exposed and theworkers work in newly exposed area which does not getsu1cient time to deteriorate.

0reparatory arrangements or stoping are not heavy.&topes can be brought into production comparatively

2uickly provided arrangements are made in advance orflling operations.

:entilation is comortable because o small area ostope or air current.


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Cut and fling Advantages (Contd.)

)ilution o ore is reduced to the minimum as thereis no spalling o wall rock.

;eneral saety in the mine is increased as there are

no old stopes to collapse or transer their roostresses to existing stope.

&econdary blasting can be done in the stope.

The method provides permanent support or

structures and other eatures on the surace whichmust not be disturbed.

6ill tailings, i they are used or flling, reduce theirdisposal problem on the surace.


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Cut and fling Disadvantages

As cut is a cyclic method, production o oreis intermittent unless a ew stopes are

worked simultaneously. hen productionoperations are suspended in one stope orflling the other stopes should be able tosupply ore.

&uitable flling material may not beavailable in all cases. Arrangements orprocuring flling material and transport tothe stope involves a sizable cost.

Documents

Cut & Fill Stoping