Study of the Effect of Blast Pattern Design on

Autogenous and Semi-Autogenous Mill Throughput at Gol-e-Gohar Iron Ore Mine

Authors: A.Hakami, H.Mansouri, M.A.Ebrahimi Farsangi, M.R.Dehghan and

F.Faramarzi

Presenter: Farhad Faramarzi

• Previous works

• About Gole-e-Gohar iron ore mine (Mine No.1)

• Fragmentation measurement

• SAG power index (SPI) test

• Conventional blast pattern vs. new blast pattern

• Mills performance before and after implementation

• Conclusions

2

Table of contents

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Previous works

• The Mine to Mill concept (McKee, 1990)

• The relationship between fragmentation in mining and comminution circuit

throughput (McKee, 1995)

• Exploring the effect of blast design on throughput at KCGM (Kanchibotla et al., 1998)

• Blasting for reduced process plant costs at Argyle diamond mine (Bulow et al., 1998)

• Mine to mill blasting to maximize the profitability of mineral industry operations (Kanchibotla., 2003)

• Blast fragmentation for maximising the SAG mill throughput at Porgera gold mine (Grundstrom et al., 2001)

• Effect of Blasting on the Strength of Rock Fragments (Kemeny., 2003)

• Optimum blasting? Is it minimum cost per broken rock or maximum value per

broken rock? (Kanchibotla., 2003)

• Optimisation of the Cadia Hill SAG mill circuit (Hart et al., 2001)

• Adjusting blasting to increase SAG mill throughput at the Red Dog mine (Paley et al.,

2001)

• Mine to mill optimisation for conventional grinding circuits – a scoping study (Jankovic and Valery ., 2002)

• Process integration and optimisation; a case study in productivity improvement (Dance et al., 2007)

• The influence of blasting on Kemess hypogene ore milling (Hikita, 2008)

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Previous works

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Throughput gains of 5-15% have been recorded and confirmed at operations

with SAG mills such as (Jankovic and Valery ., 2002):

• Highland Valley Copper (Canada)

• Minera Alumbrera (Argentina)

• Cadia (Newcrest Mining in Australia)

• Escondida (Chile)

• Porgera (Placer Dome in Papua New Guinea)

• OK Tedi (BHP in Papua New Guinea)

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Previous works

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About Gole-e-Gohar iron ore mine (Mine No.1)

Gyratory Crusher

Crusher Stock piles

Bins

Line 3- AG 9m×2.05m

Line 1- SAG 9m×2.05m

Line 2- AG 9m×2.05m

Line 4- HPGR

Thickener Concentrate Stock piles

Crusher closed side set was 20 cm SAG : Operated at 5% ball charge Critical speed for SAG/AGs: 85% Mills are operated in dry mode Mills are air swept

Muck pile and Mills’ feed size distribution:

• Split-Desktop was used to carry out image analysis.

• Delineation was done manually and the 100% fines correction option used.

• Photos were taken by a digital camera during the excavation of muck piles.

• Stock pile distribution was also photographed before, during and at the

end of implementation.

• It was not possible to stop the belts for sampling and sieving belt cuts.

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Fragmentation measurement

• MinnoveEX SPI test developed by Starkey and Dobby, 1996. • It’s a laboratory batch test to evaluate comminution behavior

rocks and also SAG mills specific energy (Amelunxen et al., 2014).

• Why SPI? It was the only available equipment for evaluation ore hardness at Gol-e-Gohar laboratory.

• How SPI was done? The time required to; 2kg sample (F80<12.7mm) 2kg sample (P80<1.7mm)

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SAG power index (SPI) test

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Conventional blast pattern vs. new blast pattern

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Mills performance before and after implementation

Throughput: 30% Energy : -21% Throughput: 5%

Energy : -4% Throughput: 14%

Energy : -14%

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Mills performance before and after implementation

374

524 472 485

549 538

0

100

200

300

400

500

600

700

1 2 3

Trou

ghpu

t (t/h

)

Mill Number

Old blast pattern New blast patternNew Blasts

April May June July August September October November December January February March

• For the first time in Iran, a mine to mill blasting approach

implemented at Gole-e-Gohar iron ore mine No.1, “ A Good Start”.

• By increasing powder factor from 1.65 to 2.48 kg/m3 by a tighter

blast pattern and so finer ROM distribution; up to 30% increase in

throughput and also up to 21% decrease in the mills’ energy

consumption achieved, “A Good Result”.

• Studies should continue at Gol-e-Gohar iron mine by more blast

practices and comminution tests; if key decision makers accept the

concept/changes “A Sweet Hope” .

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Conclusions

Shahid Bahonar University of Kerman

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Acknowledgements

Gole-e-Gohar Mining and Industrial Company

Gol-e-Gohar Iron and Steel Research Institute

Thank You! Questions?