50% Blasting Cycle efficiency improvement
Document type: Case Study

Increased Blast Size Leads to 50%
 Blasting Cycle Efficiency Improvement
 At Cracow

Project Summary
 How to Be a Safety and Security HotShot
LARGER BLASTS, REDUCED DILUTION AND
ENHANCED SAFETY
Electronic detonation has transformed production efficiency at
Newcrest’s underground Cracow Mine in central Queensland. In 2005, blasting at the steeply dipping epithermal gold and
silver mine was being managed conventionally, until the mine
struck a geo-technically sensitive stope. If pyrotechnic
detonators were used, the stability of the stope’s 10 meter
span could be compromised. Dyno Nobel’s solution was to use its electronic detonator
 ®
HotShot to mass blast and extract the ore. The results were Project Goals
outstanding. Increased accuracy allowed firing of much larger
blasts. With greater control of the firing direction, the company HIGH LEVELS OF SAFETY AND SUSTAINED
was able to reverse fire the whole stope in one mass blast, PRODUCTION
throwing the ore away from the waste backfill. The production The overall goal in 2005 was to sustain production while
benefits were tangible and the system reduced exposure of maintaining high safety standards. As conventional blasting at
charge crews to the hazards of working next to a stope void. the 10 meter span would expose charge crews to several
 charging sequences adjacent to a stope void, electronic
 detonators were selected to mass blast the stope, instead of
 Background blasting in sections.

meter span would expose charge crews to several
 charging sequences adjacent to a stope void, electronic
 detonators were selected to mass blast the stope, instead of
 Background blasting in sections. Working closely with Newcrest’s technical
 team, Dyno Nobel developed a 20-ring, 96-hole design to
A JOINT VENTURE MINING HIGH-GRADE GOLD minimize ground vibration while maintaining fragmentation and
 hanging wall and footwall conditions. Cracow is owned by a joint venture between Newcrest Mining
(70%) and Sedimentary Holdings (30%). Gold production The initial shot increased fragmentation, reduced vibrations,
 reduced dilution, and improved efficiency in hanging-wall and
began in November 2004. The high-grade gold mineralization
 footwall conditions. lies in the Royal, Crown and Sovereign shoots 100 to 600
meters underground. The Royal is approximately 350 meters The mine’s practice was to fire blasts into an open stope,
along strike and the Crown and Sovereign approximately 300 which was filled with waste backfill. As a result, ore could be
meters along strike. While there may be abrupt changes in diluted or not fully recovered, if thrown into the waste while
horizontal thickness and grade, the ore bodies’ width averages firing. 5 meters. In September 2006, a refinement to the established mining
More than 110,000 ounces of gold were produced at Cracow in practice was trialed.

and grade, the ore bodies’ width averages firing. 5 meters. In September 2006, a refinement to the established mining
More than 110,000 ounces of gold were produced at Cracow in practice was trialed. Electronic detonators allowed firing the
its first year of operation at a grade of 11.57 grams per tonne winze up to a 5 meter cap, with all rings being fired in a single
and a cash cost of $307 per ounce*. blast. This enabled the mine to change the direction of firing
 away from the waste backfill, into the void created during the
*Newcrest 2006 annual report
 firing of the winze and slot holes. Greater accuracy allowed
 short delays between blastholes, improving fragmentation and
BEFORE AFTER minimizing risk of cut-offs.

Increased Blast Size Leads to 50%
 Blasting Cycle Efficiency Improvement
 At Cracow
 Technology Applied
USING THE SMARTSHOT SYSTEM
Today, the mine uses the SmartShot™ electronic detonator
system, which enables design and implementation of
advanced blast designs. Detonators cannot fire unless the
system’s coded signal provides the correct instruction and
voltage. Electronic blasts are fired through pre-installed cable. Prior to SmartShot’s introduction in 2007, the mine used the
HotShot system, which is suitable for small to medium blasts “SmartShot’s accuracy allowed us to boost size of firings,
and can fire up to 600 detonators. decrease re-entry and design firing to minimize cut-off risk. The Cracow mine was the first to use HotShot detonators Electronics gave us full flexibility in timing, allowing us to avoid
underground. The mine now uses electronic detonators for all cut-offs in closely spaced ring holes by separating the time by
production stope blasting. Better timing control allows only a few milliseconds, rather than the full 25ms offered by
operations to improve fragmentation and throw and to reduce non-electronic detonators.”
vibration. “Increased blast size led to a 50 per cent improvement in
 blasting cycle efficiency,” Strong said. Value Added Results:
  Reduced exposure to the hazards associated with
GREATER BLAST CONTROL AND BETTER working adjacent to voids.

50 per cent improvement in
 blasting cycle efficiency,” Strong said. Value Added Results:
  Reduced exposure to the hazards associated with
GREATER BLAST CONTROL AND BETTER working adjacent to voids. Mass blasting means that
EFFICIENCY there are no open voids while charging.  Improved conventional/tele-remote bogging ratio from
According to Newcrest mine superintendent at Cracow, Nick
 10/90 to 50/50. Strong, greater blast control using SmartShot led to
  Charging time per stope reduced from approximately
significantly increased efficiency. 7 x 3-hour cycles to two cycles of 2 and 7 hours (9
“SmartShot gives us great confidence, as there is no scatter hours). and the firing sequence is guaranteed. Electronic detonation  Zero re-drills from blast damage. made mass blasting possible, when pyrotechnic detonators
  Fragmentation improved and oversize significantly
didn’t have enough range. We were able to increase time
 reduced. available for the blast from about 4 seconds to 18 and to cast
  Detonator inventory halved. broken dirt in the direction of the loader, which greatly
  Greatly improved safety profile from reduced charging
improved productivity.”
 cycles and elimination of open void.

Disclaimer This case study is provided for informational purposes only. No representation or warranty is made or intended by DYNO NOBEL INC. /
DYNO NOBEL ASIA PACIFIC PTY LIMITED or its affiliates as to the applicability of any procedures to any particular situation or circumstance or as to
the completeness or accuracy of any information contained herein. User assumes sole responsibility for all results and consequences.

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