ASIEX October 2012

Claude Cunningham

• 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

ASIEX October 2012

• Kuz-Ram – Empirical Fragmentation

• BOBCAT – Empirical, Energy concentration

• SABReX – Empirical mechanistic

• MBM - Mechanistic

• HSBM - Mechanistic

Pressure Density

Radial velocity

Axial velocity

Reaction

HSBMANFO in 100mmWeak rock

• 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

Drilling

Blasting

Shovel

Hauling

Crushing

All CostsHoly Grail:Optimum Blasting:Optimum Blasting:Optimum Blasting:Optimum Blasting:Lowest unit costLowest unit costLowest unit costLowest unit cost

Cost/m3

Fragment size

ASIEX October 2012

% Oversize

Productionrate

Safe range

ASIEX October 2012

Kuz Ram Blasting Fragmentation Curves Same mean size, varying uniformity

1%

10%

100%

0.1 1.0 10.0 100.0Size, cm

% P

assi

ng

0.80 2.00

Fines

Oversize

Mid Range:0.6 - 80Saleable andHandleable

0%

0%

12%

X50=20

4%

• 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

ASIEX October 2012

With Editing

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

ASIEX October 2012

So fragmentation isn’t that easy to understand or measure.

What about detonation energy?

• 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

ASIEX October 2012

Research at Chernogolovka, Russia.

• 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/sVoD fine – 3.6 km/s

• Will high VoD expand more?Pb = 1.43 GPa vs 0.36 GPa

(Prof A Dremin (RAS), Cranfield, AEL, over 3 years)

Coarse

Fine

(Dozens fired)

Coarse

Fine

ASIEX October 2012

So VOD is easy to measure but isn’t that easy to interpret.

What about explosive energy?

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

ASIEX October 2012

(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

For Cavity Expansion, E = 0.3 kj/cc

The implication: 200 times more work to expand the hole

than to fragment the rock...

An explanation of Shock Energy and

indication of high attenuation around

the rock skin...

0.3kj/cc

0.0015kj/cc

0

10

20

30

40

50

60

Ouch 1 Ouch 2 Spathis Cunn-Szend

Author

En

erg

y % Seismic

KineticFrag

ASIEX October 2012

• 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

ASIEX October 2012

SPONSORS

1. De Beers (South Africa)2. Debswana Diamond

Mines (Botswana)3. African Explosives

Limited (South Africa)4. Dyno Nobel (Asia

Pacific/Europe)5. Rio Tinto TS (Australia)6. Codelco IM2 (Chile)7. Placer Dome TS

(Canada)8. Sandvik Tamrock

(Finland)9. Base Metals Division of

Anglo American plc.

RESEARCHERS

Itasca (USA)

JKMRC/UQ

(Australia)AEL (SA)

Cavendish Labs

Technical AdvisorsMartin BraithwaiteFinn OuchterlonyJohn FieldIan Parker

ASIEX October 2012

Pressure Density

Radial velocity

Axial velocity

Reaction

HSBMANFO in 100mmWeak rock

ASIEX October 2012

Blue – shockRed– sonic locusGreen- contact

100 mm/ Low

150 mm/ Low

200 mm/ Low

100 mm/ Medium

100 mm/ Strong

Hole diameter

Confinement

ASIEX October 2012

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

Centre and EdgePressure Profiledfor ANFO invarious diametersand confinement

ASIEX October 2012 PETNDiluted PETN

(After Prof J E Field, Cavendish Lab, Cambridge: HSBM work

Radial cracks from intersecting shear

failure cracks

Some radial cracks from wall, allowing

gas entry

• 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

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