Masterclass2014

Blasting Science – Energy in the science of blasting

WealthUnearthed

2020 WORLD VISION (O/P)• Applying large scale open pit mining to depths equal and/or

greater than current

• Approaching depths of 1000m and greater

• Ability to mine up to Gigatonne tonnes per-annum (ore and

waste)

Issues: Increased Depth, High Capacity Production And Lower Grade Mining

• A generational transformation in bulk mining (e.g. cave mining):

• Significantly Lower cost, Safe, Continuous and High Volume Cave

Mining Production

Issues: Increased Depth, High Capacity and Lower Grade Mining

2020 WORLD VISION (U/G)

Future of mass mining - 2020 Vision in Action

Probabilistic approach to risk

Probabilistic approach to risk

Probabilistic approach to risk

Challenges and Opportunities – Open Pit

Mining of steep to vertical walls (damage control)

Increased production via “mega” blasts

Enabling Grade Engineering through Fragmentation

Mine & Mill Integration (Next generation Mine to Mill)

Continuous mining and production (e.g. IPCC systems)

Lower cost waste rock mining

Mega Blasts – Differential Blasting/Grade Engineering

Blasting Science

“The Challenge”

The study of rock breakage:

bridge between:

• Rock Engineering

• Chemistry (thermodynamics of explosives)

• Detonation and Shock Physics

• Mathematics (numerical modelling)

• Explosive Engineering

The Future of Blast Modelling

Blasting Science

The Means – Blast Modelling

“The Challenge”

HSBM – The Blast Modelling Tool

What Started the HSBM Development?

Diamond Damage from open pit blasting

A De Beers / JKMRC (University of Queensland) 2 year study

Results – Diamond liberation

Undamaged Diamonds

Driver or MotivationThe ability to better predict the blasting process and results through better understanding of both detonation and rock breakage physics. Moving away from or empirical approaches.

End pointA numerical model (Software) of the complete blasting process combining a detonation code to a Geomechanical code (state-of-the approach).

Benefit

The ability to better control the blasting process and results and to better quantify impacts or benefits of blast design changes.

THE HSBM

HSBM – Project Achievements

Phase 1: Underpinning rock breakage and detonation physics

Phase 2: Validation of software –Recognition of potential as strategic tool(blast planning tool and scenario analysis)Tool for back analysis of “failed” blasts.

Phase 3 (current): Implementation of the HSBM by the sponsors to areas of interest and some enhancements to extend the HSBM range of application

Geomechanical code

Detonation codesIdeal and non-

ideal

VixenBlo-Up

Modelling EngineDetonation

Fracturing

Fragmentation

Displacement

Near-field Damage

Rock and fragment Conditioning

Back of

detonation

driving zone

(sonic surface)

Shock front

End of

reaction

zone

Detonation modelling The rock breakage engine

The Hybrid Stress Blasting Model (HSBM)

Questions we asked ourselves

Blasting to Customer Specification & Mine to MillAbility to achieve consistent & desired blast results

Excavator productivityShovel, truck productivity

Effective application of electronic detonatorsFragmentation, vibrations, movement, etc

Deep pits Pit wall damageOptimal limit blasting practices

Ore recoveries in sublevel cavingFragmentation and subsequent flow

Narrow vein mining and tunnel developmentDiamond damage

Kimberlite blasting

Vision - A blast planning or Scenario analysis (strategic) and Back analysis tool?? How HSBM can support tactical or operational teams.

Numerical modelling HSBM code not a tool for routine blast design.

However, it will embody the complete physics of the process, useful check and calibration on more empirical methods of blast design.

Utility of the code will increase as computer power increases, a date will certainly come when the HSBM can be used routinely and conveniently in design.

HSBM – Thought leadership

“We have a working tool” Version 2.7

PLUS

A unique and rich library of learnings (documents) from the

overall study

Pushing the Economic Boundaries

Damage Control:Higher Capacity, Lower Grades

Optimising the slope design with increased knowns

Damage Mechanisms Unpacked

Damage Mechanisms Unpacked

Rock type

Major joints

Joint orientation

Burden relief

Timing direction

Limit blast vs.

production blast

Decoupling

Spacing

Unpacked – Rock Types, Major Joints

Unpacked – Joint Orientations

Unpacked – Burden Relief

Unpacked – Timing, Standoff, Decoupling

Unpacked - Spacing

The Outcomes

The Outcomes –Optimisation of Controlled Energy

Reduced

waste

stripping

Pushback

with poor

blasting with

additional

catchments

Excessive

blast

damage

Increased

ore

recovery

Increased

ore

recovery

Ore body

Steepened

slope

Reduced

blast

damage, no

additional

catchments

Synergy

Blast Optimisation to achieve safe highwalls

Reality

Investigation

Recommendations

Results

Goal

Case Study

Dynamics of a coal mine

Financial DynamicsWhat Eskom doesn’t know…..

Coal Value – R 76M

Total Cost

R 2.1M + R 57.1M = R 59M

Total Loading cost – R 57M

Blasting Cost – R 2.1M Profit

R 76M - R 59.1M = R 17.1M

Coal @ R 788.40 / t

US$ / R 10.40

Pre-split: The benchmark

The GoalThis is what a coal operation should look like…

Recipe for highwalls

Pre-Split Bench Preparation and Drilling

Excellent Bench Prep

Straight Lines

Pre-Split Blasting

Good Pre-Splits

Simple Model for Blasting (SMB)

Previous papers

Model used for prediction of energy balance & throw

Assumption required of breakout angle…

What is the correct burden angle?

Solid sandstone rock mass

Parallel cracks initiating radially from blast holes

Breakout conforms to most theory

Massive Rock Mass

Highly Jointed Rock Mass

Highly jointed hard dolerite rock mass

No evidence of formation of radial cracks

Joints existing in rock mass define fragmentation

Does not conform to blasting theory of breakout

Hard Jointed Rock Mass

Jointed rock mass – HSBM; Results

Plan view of jointed rock mass for a range of burdens

0.5m

3m

5m

Critical burden 6.8m

Good Pre-Splits

Pre-split: The reality

What really happens out there…….

Oopsie.....

The results…..

Reality check….Costing

R 4.0M/ 100meters

Analysis unpacked

What we find in the field….Post mortem of a blast

Collapsed Holes

Short Drilled Holes

Out of Line holes

Incorrect Spacing

What we find in the field….Post mortem of a blast

What we find in the field….Post mortem of a blast

I think not...

Already blasted....

Explosive Engineer at work…

RecommendationsBest practices….

RecommendationsUse current designs and practices as a base….

Frozen material agains highwall

Did not split in the upper half

Replaced pre-split bag with gasbag

Achieved a proper split

More influences…

The relationship between Inter/Over Burden and pre-splits

The Mine - bankable value

Remember this…..

90% reduction in coal

losses

The Mine Manager’s Dream

A picture speaks a thousand words……

Partnering for synergistic benefits…change catalysts

Explosive Supplier

Mine

Technical Production

Reality

Investigation

Recommendations

Results

Goal

Thank You

Masterclass2014

Blasting Science – Energy in the science of blasting