Mining_Methods_UnderGround_Mining - Mining and Blasting
Mining_Methods_UnderGround_Mining - Mining and Blasting
Mining_Methods_UnderGround_Mining - Mining and Blasting
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CAF fill<br />
Secondary<br />
BaCkFilling<br />
Primary<br />
Tertiary<br />
Unmined<br />
Unmined Secondary<br />
Designed stopes<br />
ROCK fill<br />
Primary<br />
Secondary stope extractio n<br />
CAF filled on side adjacent to unmined stope<br />
ROCK filled on side adjacent to mined stope<br />
Stope extraction <strong>and</strong> filling sequence at Olympic Dam.<br />
on the design, as do the fill mix <strong>and</strong><br />
strength attainable using available ma-<br />
terials. Fill quantities will determine the<br />
size of the preparation <strong>and</strong> placement<br />
systems, <strong>and</strong> the location <strong>and</strong> eleva-<br />
tion of stope openings relative to sur-<br />
face facilities such as tailing dams <strong>and</strong><br />
concentrator are major considerations.<br />
Mine planners focus on tailormade fill<br />
to save cement costs by strengthening<br />
the fill only where it is required, close<br />
to the stopes to be mined, such as at<br />
Olympic Dam.<br />
Underh<strong>and</strong> cut <strong>and</strong> fill mining sequence.<br />
Low cement<br />
content<br />
High cement<br />
content <strong>and</strong><br />
reinforcement<br />
Slice 1<br />
Slice 2<br />
Slice 3<br />
Unmined<br />
CAF fill<br />
Unmined<br />
Unmined<br />
Hydraulic fill<br />
Originally, backfill comprised waste<br />
rock, either from development or h<strong>and</strong><br />
picked from broken ore. Some larger<br />
mines in the US quarried rock <strong>and</strong> gravitated<br />
it down fill raises to the mine<br />
workings.<br />
Nowadays, rock fill is used for fil-<br />
ling secondary <strong>and</strong> tertiary stopes,<br />
<strong>and</strong> is usually a convenient <strong>and</strong> economic<br />
means of disposal for waste from<br />
development.<br />
The first hydraulic fills were composed<br />
of concentrator tailings that would<br />
otherwise have been deposited on the<br />
surface. The mill tailings were cycloned<br />
to remove slimes so that the contained<br />
water would decant.<br />
This fill was transported under-<br />
ground as slurry, composed of around<br />
55% solids, which is the typical underflow<br />
for thickeners <strong>and</strong> is the pulp density<br />
normally used for surface tailings<br />
lines.<br />
When the grind from the mill was too<br />
fine for decanting in the stopes, alluvial<br />
s<strong>and</strong> was employed instead of tailings.<br />
Particles of alluvial s<strong>and</strong> are naturally<br />
rounded, enabling a higher content to<br />
be pumped than for hydraulic fill made<br />
from cycloned tailings. This type of fill<br />
is commonly referred to as s<strong>and</strong> fill.<br />
Many mines still employ non-cemented<br />
hydraulic fill, particularly for filling ter-<br />
tiary stopes.<br />
The quantity of drain water from hydraulic<br />
backfill slurry containing 70%<br />
solids is only a quarter that resulting<br />
from a 55% solids mix.<br />
The porosity of hydraulic backfill is<br />
nearly 50%. It may be walked upon just<br />
a few hours after placement, <strong>and</strong> will<br />
carry traffic within 24 hours.<br />
44 underground mining methods<br />
Unmined<br />
Unmined<br />
Primary stope extracted<br />
CAF filled due to unmined adjacent stopes<br />
CAF fill<br />
ROCK fill<br />
Secondary stope extracted<br />
CAF filled on side adjacent to unmined stope<br />
ROCK filled on side adjacent to mined stope<br />
Hydraulic fill<br />
Slice 4 Face 1 Face 2<br />
Unmined<br />
Unmined<br />
Unmined<br />
2nd Primary stope extracted<br />
CAF filled due to adjacent unmined stopes<br />
ROCK fill<br />
CAF fill<br />
Tertiary stope extracted<br />
ROCK filled as no adjacent stopes