Measurement and Analysis of Blast Fragmentation

163 Pages·2013·21.244 MB·English

by  Jose A. Sanchidrian Blanco (ed.), Ashok Kumar Singh (ed.)

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OK KUMAR SINGH EDITORSÉ A. SANCHIDRIÁN
Fragmentation characteristics influence mucking productivity, crusher throughput M
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and energy consumption, plant efficiency, yield and recovery, or the price itself
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of the end product in the case of industrial minerals and aggregates. Reliable,
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quantitative measurements of fragment sizes are instrumental in controlling and R
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optimizing the blasting results. M
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Measurement and Analysis of Blast Fragmentation presents the latest devel-
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opments in rock fragmentation measurement techniques and analysis. It includes n
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image analysis and machine vision techniques, either photographic or 3D such
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as stereo-photogrammetry and laser triangulation; case studies of fragmentation
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measurements in a variety of situations and used in different optimization and L
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control tasks; fragmentation analysis and new suitable functional descriptions of
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size distributions, and model-scale fragmentation tests with weighed size distribu-

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tion data. f

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The contributions in this book were presented at the workshop Measurement and
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Analysis of Blast Fragmentation, which was hosted by Fragblast 10 (New Delhi,

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India, November 2012). They provide a snapshot of the activity in rock fragmenta- R
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tion measurements and analysis around the world and are a must-have reference G
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for engineers and researchers working in rock blasting
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ASHOK KUMAR SINGH
EDITORS
WS Fragmentation FINAL.indd 1 11-10-2012 12:13:05
MEASUREMENT AND ANALYSIS OF BLAST FRAGMENTATION
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WORKSHOP HOSTED BY FRAGBLAST 10 — THE 10TH INTERNATIONAL SYMPOSIUM ON
ROCK FRAGMENTATION BY BLASTING, NEW DELHI, INDIA, 24–25 NOVEMBER 2012
Measurement and Analysis
of Blast Fragmentation
Editors
José A. Sanchidrián
Universidad Politécnica de Madrid – ETSI Minas, Madrid, Spain
Ashok Kumar Singh
Central Mine Planning & Design Institute Limited, Ranchi, India
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Version Date: 20130321
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Measurement and Analysis of Blast Fragmentation – Sanchidrián & Singh (Eds)
© 2013 Taylor & Francis Group, London, ISBN 978-0-415-62140-3
Table of contents
Preface vii
Organising Institution ix
Committees xi
Sponsors xiii
Technology developments
A history of digital image analysis technique for blast fragmentation assessment and some
Indian contributions 3
A.K. Raina
Automated rock fragmentation measurement with close range digital photogrammetry 13
M.J. Noy
Automated, on-line, calibration-free, particle size measurement using 3D profile data 23
M.J. Thurley
Surfometric imaging for dimensional analysis of individual aggregates and bulk samples 33
G. Dislaire, P. Illing, C. Laurent, E. Pirard, P. Di Carlo & C. Moitroux
Designing and optimising surface blasts using 3D images 41
M. Pötsch, A. Gaich & R.A. McClure
Fragmentation testing
Experimental blast fragmentation research in model-scale bench blasts 51
P. Schimek, F. Ouchterlony & P. Moser
Fragmentation under different confinement conditions and the burden behavior—small
scale tests 61
N. Petropoulos, D. Johansson & F. Ouchterlony
Size distributions
A three parameter rock fragmentation distribution 73
A.T. Spathis
On the performance of truncated distributions to describe rock fragmentation 87
J.A. Sanchidrián, P. Segarra, L.M. López, F. Ouchterlony & P. Moser
Applications of fragmentation measurement
Assessment of objective based blast performance: Ranking system 99
V.R. Sastry & K.R. Chandar
Return on experience from full-scale open pit blasting experiments 107
F. Delille, D. Goetz & B. Tessier
Fragmentation risk assessment in open-pit blasting using interaction matrix-vulnerability
index method 115
F. Faramarzi, H. Mansouri, M.A.E. Farsangi & M. Monjezi
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Optimisation of blast design for an iron ore mine and assessment of fragmentation through
image processing 123
H.S. Venkatesh, K. Vamshidhar, G. Gopinath, A.I. Theresraj & R. Balachander
Research on prediction of average blasting fragmentation based on BP neural network 133
G.Q. Zhang, T.J. Tao, X.G. Wang & C.P. Wu
Assessing the effect of rock mass properties on rock fragmentation 139
A.K. Sirveiya & N.R. Thote
Author index 145
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Measurement and Analysis of Blast Fragmentation – Sanchidrián & Singh (Eds)
© 2013 Taylor & Francis Group, London, ISBN 978-0-415-62140-3
Preface
The assessment of fragmentation by blasting and by any of the subsequent crushing and grinding stages is
important in order to control and optimize the mining operation. Fragmentation characteristics influence
the mucking productivity, crusher throughput and energy consumption, plant efficiency, or the price itself
of the end product in the case of industrial minerals and aggregates.
It is clear to everyone that measuring and reporting rock fragmentation means obtaining a
size-percentage passing curve of the blasted rock. However, the precise meaning and complications of
such size-passing relation are in many cases overlooked. In statistical terms, determining a distribution
of sizes involves measuring the sizes of the particles by any suitable gauge system, building a histogram
of sizes and deriving a density function of size thereof. Besides this being impossible to carry out with
rock samples, usually involving millions of particles, it is not the histogram of numbers, or frequencies, of
particles of a given size interval that is of interest, but the amount of material in each size interval. What is
meant by amount of material is, in the usual sieving procedure, the mass, or mass fraction, in each interval
of mesh size, which represents a discrete density function of the mass for each size. The corresponding
representation of the mass fraction of material with size less than a given mesh is a discrete cumulative
distribution, the well-known size-fraction, or percentage, passing curve. This is the standard representation
of rock fragments size distribution.
Sieving is almost impossible to carry out in a large scale on a permanent basis in a mining operation
since it is disruptive of the production work and extremely expensive in time and human resources, though
some experiences of full scale sieving exist. In small scale, blasts can be done in a fully controlled way and
fragmentation can then be measured accurately by sieving and weighing. Significant experimental efforts
to understand the mechanisms of rock fragmentation are being done on the basis of small scale blasting,
and two papers on this research area are presented in this volume.
Image analysis techniques have been used for particle size measurement in the last thirty years. As
computers and high resolution cameras have become popular and inexpensive, the cost of an image
analysis system is relatively low and particle size and shape analyses can be handled easily. For operational
control purposes (of blasting, crushing, etc.), sampling and sieving encompass a late feedback of the size
distribution data, while image analysis systems can determine the size distribution on-line with reasonable
accuracy, and with a set up such that images are taken in the production environment without interfer-
ing with the production process. The solutions adopted for image acquisition are very much application
dependent but they classically involve 2D camera systems; computational methods involve techniques to
elaborate images transformed into numerical information in order to extract edges and delineate (or seg-
ment) particles. Segmentation routines are aimed to determine gray intensity or color changes to assign
edges or boundaries, this way determining the size and shape parameters of the particles. In this case, usu-
ally the size distribution is obtained from the number of particles in size classes, or from the surface cov-
ered by them; the amount of material in this case is not mass, but surface, or number of particles. If mass
fractions are required, they must be estimated from those by means of experimental conversion factors.
In 1996, on the occasion of Fragblast 5 in Montreal, Canada, a workshop was held that reviewed the
state of the art technology on image processing applied to rock fragmentation measurement. It was a
brilliant gathering of technical and scientific knowledge and its proceedings volume is, even today, one of
the top cited references amongst the blasting community. At that time, image processing was an emerging
technology; since then, it has grown and evolved through the years and its use has spread in the mining
sector. Along with mathematical research, the development of higher resolution cameras and computers
with ever increasing capacity and processing speed have made image analysis a relatively mature technol-
ogy today, with a number of products available off-the-shelf; image analysis systems are not rare nowadays
in mining operations. Difficulties and errors of the image processing techniques are well identified, some
of them stemming from the physics of the measurement itself (i.e. trying to measure a property of the
bulk of a material by sampling only on its surface, such as segregation, overlapping, capturing errors, etc.)
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and others from the unavoidable inaccuracies of the algorithms (e.g. segmentation errors arising from the
fact that particles usually have similar texture which makes it difficult to differentiate between particles,
and texture or color changes within a single particle that may be wrongly interpreted as boundaries).
Methods for measuring the third dimension have been developed by different techniques, such as stereo-
photogrammetry, laser triangulation or laser scanning. The leading edge of research in fragmentation
measurement by machine vision stands in these 3D systems, of which several solutions are discussed in
this volume.
There is no single approach that will solve the fragmentation measurement problem at every site. Practical
implementation of image analysis systems include taking images of the muckpile, dipper, truck loads, fall-
ing material from trucks while dumping, crusher hoppers and feeders, conveyor belts, etc. A variety of
case studies in which fragmentation by blasting is measured and applied to blasting assessment is pictured
in several papers hereafter. The combination of measurement and analysis techniques based on Statistics,
optimization techniques, on-site calibration and data reconciliation provides an undoubted solution for
accurate fragmentation measurement and control. Appropriate functional descriptions of the fragment
size, beyond the classical Weibull distribution, may also be instrumental in this task; research in this aspect
of fragmentation analysis is also reflected in this volume.
The aim of the workshop has been to bring together researchers and practitioners in the field of
measurement and analysis of fragmentation by blasting: developers of measurement systems, users of
such systems, along with researchers on fragmentation by blasting performing actual fragmentation
measurements by sieving, and also analysts seeking to describe fragmentation by improved distribution
functions. Contributions have come from Australia, Austria, Belgium, China, France, India, Iran, Spain
and Sweden. This does not make it a comprehensive volume on fragmentation measurement and analysis
but it delivers a snapshot of the activity in this field around the world, while the workshop itself provides
an opportunity for speakers and attendees to share their experience and their knowledge, to analyze and
to discuss the evolution of new techniques and to devise new scenarios where fragmentation measurement
techniques can be applied.
We thank the Fragblast International Organizing Committee for the long term support of blasting
research and technology worldwide, through the organization of the prestigious Fragblast Symposia.
We also thank the National Organizing Committee of this Tenth International Symposium on Rock Frag-
mentation by Blasting for the initiative of hosting this workshop on fragmentation measurement and
analysis, and for providing an excellent support to it throughout. We wish to thank very especially the
reviewers for their silent and efficient work and, above all, the authors for taking their time for writing
their papers and for sharing their experience and knowledge with all our community.
José A. Sanchidrián
Universidad Politécnica de Madrid – ETSI Minas, Madrid, Spain
Ashok Kumar Singh
Central Mine Planning & Design Institute Limited, Ranchi, India
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Measurement and Analysis of Blast Fragmentation – Sanchidrián & Singh (Eds)
© 2013 Taylor & Francis Group, London, ISBN 978-0-415-62140-3
Organising Institution
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