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Reverse Circulation. Halco History. Reverse Circulation. EXPERTS. Halco - Reverse Circulation. Conception. RC drilling was introduced over 15 years ago as an alternative to core drilling. Almost half the cost of traditional core drilling.
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Halco History Reverse Circulation EXPERTS
Halco- Reverse Circulation Conception • RC drilling was introduced over 15 years ago as an alternative to core drilling • Almost half the cost of traditional core drilling • 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 • Ability to drill through broken or fractured rock • Returns uncontaminated samples unlike RC drilling operations using cross over subs
Halco- Reverse Circulation RC Drilling using DTH hammer, bit & cross over sub Sample Contamination Sample Contamination
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 • Continuous samples making logging extremely easy for the geologist • Ability to give fast results in hard deposits where high value minerals are usually found • RC equipment is flexible and can be used in other drilling operations such as • Water Well • Soil Investigation • Construction • Mine Development
Halco- Reverse Circulation Principles • Retrieved sample split into 2 portions 87.5% 12.5% • 87.5% marked, bagged and remains on site next to the bore • 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: • RockType • Structure • Alteration • Mineralogy • Small sample kept in chip tray for records • 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 • 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 Swivel Exhaust air returns sample to hopper via the inside of the bit, hammer, dual wall rods, swivel and rotation head 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 • 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 In coming Air Exhaust Air
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 • Redesigned sample tube provides 25% longer life • Reversible cylinder increases life by a further 20%
Halco- Reverse Circulation Halco RC5 Reverse Circulation Hammer • Hammers available with a wide choice of top adaptors • Re-designed back head assembly allows for a shorter lighter product • New innovative drill bit head design • Returns the highest quality uncontaminated sample • Trials undertaken in the most extreme conditions