Claude Cunningham
ASIEX October 2012
• • • •
Where are we? What we think we know What we aren’t good at Getting it right
ASIEX October 2012
• • • •
Where are we? What we think we know What we aren’t good at Getting it right
ASIEX October 2012
• • • • • • • • •
Mining and Construction Companies Blasting Contractors Explosives Companies Academics Consultants Government Public Law firms Insurance Companies
ASIEX October 2012
• • • • • •
Blasting Consultants: a rare breed Engineers usually in transition Hard to differentiate levels of competence Expertise in one area seen as all-encompassing Lack of standards or recognition “Free” advice from Explosives Companies
ASIEX October 2012
• Blasting increasingly serious discipline • Enabling effects • Environmental • Security/Safety
• Blast Engineering too big to be part of Mining • Main entry via Explosives Makers (EM’s) • EM’s truly focussed on volumes, not effects • Low volume blasting can need greatest expertise • Career growth in tech not viable: punish tech choice
• Need for proper degree courses ASIEX October 2012
• Mining Degree: NIL! (survey, rock mech, geology useful) • Masters Degree • USBM research papers • Langefors and Kihlstrom • High Speed Photography, Dynamic strain models
• Explosives Company 33 years (AEL) • • • • •
Archives, Courses, Chemists, Specs, Explosives engineering Research projects – Kuz-Ram, Compa-photo, ED’s etc. etc. International Liaison - ICI group/ modelling, RAS (Dremin) Conferences – ISEE, Fragblast, EFEE, Explo HSBM – Global detonation and rock modelling specialists
• Consulting: Hands-on, fully documented, intense ASIEX October 2012
Pressure
Density
• Kuz-Ram – Empirical Fragmentation Radial velocity
• BOBCAT – Empirical, Energy concentration Axial velocity
• SABReX – Empirical mechanistic • MBM - Mechanistic
HSBM ANFO in 100mm Weak rock
• HSBM - Mechanistic
Reaction
ASIEX October 2012
• Prediction not great, post-analysis ok • Initial thought: mechanistic models the answer • Empirical models tend to do better • Because based on field measurements • More easily calibrated • But minimal physics
• Mechanistic: excruciatingly difficult physics • Immense computing • Dearth of useful field data • Too slow for field application
• So what is the use of models? ASIEX October 2012
• Powder Factor is also a model, with no output! • Prediction gives expectation to measure against • And raises awareness of what needs to be measured • Improvement of measuring technology
• Forces focus on input parameters • Collection of data
• Questions raised on ever-higher planes • Drives research
• Common language for training • Calibration process leads to advances • Provides framework for blast design ASIEX October 2012
• Intuition often wrong • Things that should work don’t • Things that shouldn’t work do
• “Optimised Blast Design” • “Controlled fragmentation”
• “Measured fragmentation” • Effect of Detonation Velocity • Where explosive energy goes
ASIEX October 2012
Holy Grail:
All Costs
Optimum Blasting: Lowest unit cost
Cost/m3 Crushing Shovel Hauling Blasting Drilling Fragment size
Production rate
Safe range
% Oversize
ASIEX October 2012
Kuz Ram Blasting Fragmentation Curves Same mean size, varying uniformity
0%
100%
12%
0.80 2.00
Oversize
g n i s s a P %
X50=20
10%
4%
Fines
Mid Range: 0.6 - 80 Saleable and Handleable 0%
1% 0.1
1.0
Size, cm ASIEX October 2012
10.0
100.0
• What fragmentation? • Mean size? (what range?) • Fines? ( = waste, degradation) • 20 % fines = 20% loss of resource, disposal • Oversize? ( = Showstopper) • Omits breaking to grade as an issue
ASIEX October 2012
With Editing
ASIEX October 2012
ASIEX October 2012
• Almost impossible to get real production data • Imaging systems cannot handle muckpiles or fines: • Mass, shape and lighting factors • “you cannot measure what you cannot see” • “you should not extrapolate where there is no check”
• Ok with even, coarse material.
ASIEX October 2012
So fragmentation isn’t that easy to understand or measure. What about detonation energy?
ASIEX October 2012
• Universal faith in Pdet = ρD2 /4 • General faith that: Higher VOD = More Energy • And complete confusion as to implications for blasting: Backbreak, Fragmentation, Throw. • Repeated claims that propellants are “more efficient and cleaner”.
ASIEX October 2012
Research at Chernogolovka, Russia. (Prof A Dremin (RAS), Cranfield, AEL, over 3 years)
• Two 30/70 TNT/AN formulations: • Coarse and fine grain • Same density - 0.88g/cc • Confined in 28 mm steel pipe within sand buffer. • VoD coarse – 1.8 km/s VoD fine – 3.6 km/s • Will high VoD expand more? Pb = 1.43 GPa vs 0.36 GPa
C o a r s e
F i n e
C o a r s e
F i n e
(Dozens fired) ASIEX October 2012
So VOD is easy to measure but isn’t that easy to interpret. What about explosive energy?
ASIEX October 2012
Usable
Seis
Heave
Frag
Loss
%
%
%
%
%
Q1
65
7
8
0.15
40-50
Q2
55
3
12
0.2
25-35
Spathis
60
5
27
0.3
25
(Ouchterlony, 2003) ASIEX October 2012
Cavity expansion and brittle materials Concrete:
Powder factor ~ 0.5kg/m3 in blasting. Energy factor = 1.5 MJ/m3 = 0.0015 kJ/cc or !a"ity E#$ansion% E = 0.3 k&/cc
'(e im$lication) *00 times more work to e#$and t(e (ole t(an to fragment t(e rock... 0.3k&/cc
+n e#$lanation of ,(ock Energy and indication of (ig( atten-ation aro-nd t(e rock skin... 0.0015k&/cc ASIEX October 2012
60 50 %40 y g r 30 e n E 20
Seismic Kinetic Frag
10 0 Ouch 1
Ouch 2
Spathis
Author
ASIEX October 2012
CunnSzend
• Grossly overestimating “gas” losses through collar. • Movement of face takes tiny portion of energy. • “Shock” really does the important work
ASIEX October 2012
• Important conflicts in blasting theories and ideas • Blast training and engineering dominated by explosives companies, usually low level • Excessive secrecy with useful data • Lack of cooperation and synergy • Poor connection with Chemists, Physicists, Maths, Geotech • Blasting research is expensive
ASIEX October 2012
• Inefficient blasting controlled by blaster focussed on
production, or • Ineffective blasting controlled by manager focussed
on limiting D&B cost • Commercial “Blasting Seminars” • D&B a dirty and onerous process: need real interest and reward for trying hard. • But real potential for continuous, significant, positive impact on operations
ASIEX October 2012
SPONSORS
RESEARCHERS
1. 2.
Itasca (USA) JKMRC/UQ (Australia) AEL (SA) Cavendish Labs
3. #. . +. .
*echnica Ad!isors Martin Braithwaite inn 4uchteron$ 5ohn ied -an &ar0er
/. .
ASIEX October 2012
De Beers (South Africa) Debswana Diamond Mines (Botswana) African Exposi!es "imited (South Africa) D$no %obe (Asia &acific'Europe) io *into *S (Austraia) ,odeco -M2 (,hie) &acer Dome *S (,anada) Sand!i0 *amroc0 (inand) Base Metas Di!ision of Ano American pc.
Pressure
Density
Radial velocity
Axial velocity
HSBM ANFO in 100mm Weak rock Reaction
ASIEX October 2012
100 mm/ Low Hole diameter
150 mm/ Low Blue – shock Red – sonic locus Green - contact
200 mm/ Low
100 mm/ Medium Confinement
100 mm/ Strong ASIEX October 2012
Centre and Edge Pressure Profiled for ANFO in various diameters and confinement
100 mm 0.8 g/cc
150 mm 0.8 g/cc
200 mm 0.8 g/cc
100 mm 4 g/cc
100 mm 8 g/cc
ASIEX October 2012
(After Prof J E Field, Cavendish Lab, Cambridge: HSBM work Radial cracks from intersecting shear failure cracks
ASIEX October 2012
Some radial cracks from wall, allowing gas entry
PETN
Diluted PETN
• Technology • Knowledge, Method, Systems and Equipment for achieving desired results
• Finance: Costs, Consequences, Value • Charging enough, Paying enough, Reaping enough reward for sustainability
• People: Blasters/ Suppliers/ Customers/ Consultants • Each involved person trained, consulted and recognized
• Legitimacy/ Values • Benevolent intent, Transparency, Justice, Courage, Temperance
ASIEX October 2012
• The guy at the face – has to handle the results: dislikes delay and struggle. • Shovel operator, dragline driver, truck supervisor, chief engineer
• The plant foreman • Throughput, steel costs, replacements, recoveries, waste.
• But often ignored through normal clashes.
ASIEX October 2012
• • • • • • • • •
There are no issues that are not people issues There are no costs that are not people costs Distrust, secrecy, bureaucracy disable synergy Sharing is risky but very rewarding In blasting, we do not share enough! Progress is therefore very slow and isolated We need to share more, even if it feels risky Identify and isolate trolls who only take And actively resist moves to limit sharing
ASIEX October 2012
• Trying to patent blast timing designs • • • • •
How can this help progress? Shuts down the most basic communication and sharing Policing it would be a nightmare anyway Who takes the risk with timing designs? Patent the system, not the timing!
• Unlimited Non-Disclosure clauses • Should release data older than 5 years • If owner can’t mine the data by then, give it to someone who can • Need external peer-review for real learning
• Tech Conferences polluted by Marketing agendas ASIEX October 2012
• Grow a professional class of blasting engineers, don’t see it as a transient career. • Ensure proper peer review! • Link all clients of blasting process together to give practical feedback • Track whole value chain created by blasting • Share learning, foster debate!
ASIEX October 2012
