Drill Selection – What Do I Pick? Bill Hissem
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Drill Selection – What Do I Pick?
Bill Hissem
50,000
40,000
30,000
120,000
100,000
80,000
60,000
Down-The-Hole
(Air)
Top
Hammer
Air &
Hydraulic
* Hole Diameter
20,000
10,000
60,000
40,000
20,000
Rock Strength
(PSI)
Pull-Down Weight
(LBS)Drilling Domains
Rotary
Tri-ConeDrag
Bit
1 2 3 4 5 6 7 8 9 10 11 12 13 14 15Hole Diameter (inches)
* General Configuration
DTHTop - Hammer DTH - Trackdrill
* Primary DifferenceDTHTop - Hammer
Puts more
percussion energy
in the hole
Puts more
flushing air
in the hole
Rotary
Puts more
flushing air
in the hole
* Hammers
DTHTop - Hammer
350 PSI
Operating Pressure
2300 PSI
Operating Pressure
* Bit Penetration Rates
DTHTop - Hammer
Penetration Rate
Fast
Hard Rock
Soft Rock
1 2 3 4 5 6 7 8 9 10
Slow
Hard Rock
Hole Diameter (inches)
* Drill String ElementsDTHTop - Hammer
“Drill Rod”
Thick Wall Pipe
“Drill Pipe”
Thin Wall Pipe
Lift Plug
Top Sub
Drill Pipe
Bit Sub
Rotary Bushing
Petol Tong
DTH Hammer
Petol Chain
Bit Basket
X-Section X-Section
* Fuel
DTHTop - Hammer
Compressed
Fluid (hydraulic oil)
Compressed
Gas (air)
300 liters 1000 liters
per
10 hr-shift
per
10 hr-shift
70 % Volume consumption rate difference
80 % Cost per Dr-Ft difference in production
OK – How do I pick out a drill?
Or Not?
Drill ownership and operation in-house
oror
Contract Drilling
Drill type determines energy distribution within the shot:
• Hole diameter
• Hole straightness
OK – How do I pick out a drill?
Explosive energy + rock fabric determine fragmentation:
• Charge diameter
• Drill pattern
Ownership or Contract Drilling requires an understanding of true costs, effect, and
outcome for each case
Typical desired outcomes:
• Easy to load muck pile
• Little or no oversize
•
Drilling is the foundation for explosives distribution in the shot
• Controlled muckpile shape
• Minimum fines and overburden material content
• Safe blast event
• Minimum off-site disturbance in urban neighborhoods
• Minimum overall quarrying costs
• Maximum overall quarrying productivity
OK – How do I pick out a drill?
Or Not?
Whether you own the drill or not, drilling is required.
So the real question is whether I can So the real question is whether I can get the quality and quantity of drilling I need at a cost equal to or less than the expense of an in-house drilling program.
Consider each of these criteria as they apply to your site and organization, assigning value according to your priorities.
There are 3 approaches taken in drill selection:
There are 3 approaches taken in drill selection:
There are 3 approaches taken in drill selection:
Drill Selection
• Establish your criteria
• Eliminate drill alternatives that
don’t fit the application
• Evaluate support issues
• Run cost analysis for each
scenario for comparison
What are the advantagesof drill ownership?
Operational• Control of Training • Schedule as needed• Daily driller communication
Economic• Low $/ton with good utilization• Specialized Drilling• Better if no viable contractors
are available
What are the advantagesof a Contract Driller?
• Can backstop spot production demands
• Requires no mechanical support• Requires no mechanical support
• Fewer operators required (more staff ?)
• More predictable operating $ budget forecast ?
What to look for in a Contract Driller
•MHSA/Safety Compliance - Part 46
•Well trained, dependable staff
•Internal back-up fleet capacity
•Insurance/bond capacity
•Equipment in good order - reliable
•DOT concerns – compliance
•Schedule response availability
•Ability to deliver required production - accurate holes
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