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Reverse Circulation
Halco History
Reverse
Circulation
Halco- Reverse Circulation
Conception
•
RC drilling was introduced over 15 years ago as an
alternative to core drilling
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Almost half the cost of traditional core drilling
•
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Over five times faster than core drilling, particularly in
hard rock
RC drilling is used for deep exploration holes on
Greenfield sites
Also used in mines for grade control
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Ability to drill through broken or fractured rock
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Returns uncontaminated samples unlike RC drilling
operations using cross over subs
•
Halco- Reverse Circulation
RC Drilling using DTH hammer, bit & cross over sub
Halco- Reverse Circulation
RC Drilling using RC hammer & bit
The hole is sealed by the bit
catcher and design of the drill
bit head
Halco- Reverse Circulation
Principles
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Continuous samples making logging extremely easy
for the geologist
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Ability to give fast results in hard deposits where high
value minerals are usually found
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RC equipment is flexible and can be used in other
drilling operations such as
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Water Well
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Soil Investigation
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Construction
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Mine Development
Halco- Reverse Circulation
Principles
Retrieved sample split into 2 portions
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87.5%
12.5%
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87.5% marked, bagged and remains on site next to
the bore
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12.5% placed in Callico bags marked with bore hole
information and sent for analysis
Halco- Reverse Circulation
Principles
•
Every metre the bore is logged with a sieve to
identify:
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RockType
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Structure
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Alteration
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Mineralogy
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Small sample kept in chip tray for records
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Onsite Geologist may measure the remnant
magnetic properties to aid results
Direction and depth of hole is also monitored by use
of a down hole survey machine
•
Halco- Reverse Circulation
Operation
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The principal operation of a Reverse Circulation
hammer is the same as a standard DTH hammer
•
RC hammers are pneumatically driven by
compressors
•
The piston in a RC hammer is the only major moving
part
•
As the piston impacts directly onto the bit the
penetration rate is not effected by the depth of the
bore
Halco- Reverse Circulation
Rotation
Head
Live air from the compressor enters the drill
string through the swivel and operates
hammer
Exhaust air returns sample to hopper via the
inside of the bit, hammer, dual wall rods,
swivel and rotation head
Swivel
Dual Wall
Drill Rod
Return
Hose
Hopper
Hammer
Bit
Halco- Reverse Circulation
Operation
•
Air enters the drill string from
the compressor via a side inlet
swivel
•
Live air travels down the
outside of the dual wall swivel
and drill rod into the hammer
•
Exhaust air containing the
sample returns through the
centre of the bit, drill rod and
swivel into the hopper
Halco- Reverse Circulation
Operation
•
In coming
Air
Exhaust
Air
When air exhausts through the bit, due to the bit head
design and the bit catcher acting as a seal, the debris
is forced back through the centre of the bit
Halco- Reverse Circulation
Halco- Reverse Circulation
Blow Down Adaptor
Converts all the air from the
compressor to clear any
blockages below the point it
is placed in the drill string
Blow Back Adaptor
Converts all the air from the
compressor to clear any
blockages above the point it
is placed in the drill string
Halco- Reverse Circulation
RC “Back Wash” System
Clears blockages in the
system by diverting the air
from the compressor by
using stop valves and non
return valves
Halco- Reverse Circulation
Halco RC5 Reverse Circulation
Hammer
•
RC hammers and bits follow the high performance
design associated with traditional DTH equipment
•
Halco RC hammers and bits have the ability to
withstand high pressure booster compressors
•
Improved cylinder and piston porting give 5% more
power than the RC512 hammer
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Redesigned sample tube provides 25% longer life
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Reversible cylinder increases life by a further 20%
Halco- Reverse Circulation
Halco RC5 Reverse Circulation
Hammer
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Hammers available with a wide choice of top
adaptors
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Re-designed back head assembly allows for a
shorter lighter product
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New innovative drill bit head design
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Returns the highest quality uncontaminated sample
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Trials undertaken in the most extreme conditions