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By M Fitzgerald

Fimiston Open Pit is operated by Kalgoorlie Consolidated Gold Mines (KCGM) as a joint venture between Barrick Gold and Newmont Mining. Over 110 years of underground mining resulted in the development of nearly 3500 km of underground workings including backfilled and open stopes up to half a million tonnes in size. These voids significantly complicate blasting processes at KCGM, influencing blast movement direction and magnitude. Blast movement monitoring to improve mine reconciliations was identified as an improvement project in the business plan for the geology team in 2008. Following successful trials in 2008 to 2009, blast monitoring and translation of ore blocks were implemented as a permanent grade control program from late 2009 and is now part of the Management Operating System (MOS) of the mine. This paper presents a summary of results from the Blast Movement Monitoring (BMM®) data collected to date. Ore blocks at KCGM are translated primarily using BMM® data. This data is obtained from the BMM® system which measures the movement of a radio transmitter installed in a blast pattern from a preblast position to a post-blast position. The application of the data collected by the BMM® tends to be both mine site and blast specific. At KCGM, an average distance obtained from the BMM® data within a given shot is the primary method used for translation. In the case that BMM® data is unavailable, a theoretical movement vector established from Orica Shotplus with distances gained from the historical BMM® database is used. Data is presented in an ore loss and dilution exercise for a bench undertaken at KCGM to understand the potential effects on reconciliations. Improvements that have flowed from implementing blast monitoring include improved reconciliations when combined with other grade control improvement projects. The increase in liaison between the geology and blast personnel at KCGM has been a significant improvement gained from the implementation of the blast monitoring program. This has allowed a better understanding of blast movement and the effects on ore dilution and ore loss by the mine geology team. In addition, the discussion of blasting tie-in plans between geology and blasting personnel has been improved which leads to more favourable blasting practices that take ore movement into account.

Aug 22, 2011

By D Thornton

Geologists use large data sets and spend many hours and much computing time modelling the distribution of minerals throughout a rock mass. Significant investments in drilling, assaying and quality assurance and quality control (QA/QC) are made before sophisticated geostatistical techniques are applied to the collected data. A large amount of research has been done in this field such that the ore control model is a reasonably accurate reflection of the mineral that is actually in the ground. However, after all this effort, the mining engineers then work just as diligently to blast the in situ rock mass to a particle size that can be efficiently handled and further reduced by downstream comminution processes. In open cut mines, this invariably requires large amounts of explosive energy that displaces the ore boundaries from where the geologists originally defined them. Failure to accurately account for blast movement will result in misclassification, whether that is ore to waste; low grade to high grade; sulfide to oxide; or other contaminates û collectively referred to as ore loss and dilution. The financial consequence of getting this wrong is substantial and not well quantified. This diminishes all of the good geological QA/QC done in defining the ore. This paper discusses various technologies used to physically measure blast-induced orebody movement and the difficulties in modelling this with a purely theoretical approach. Rock mass structure, blast energy, design and timing contours all have significant and interrelated effects on blast movement vectors. Measured blast movement has a large variance due to the uncertainly of many of the controlling parameters û arguably dominated by the heterogeneous nature of the rock mass. Although there have been significant advances in blast movement modelling capability in recent years, this unpredictable blast movement limits their use in the context of production ore control. Certainly, without physical field measurements, accurate predictions of movement are near impossible.Limitations of traditional surface markers in determining three-dimensional (3D) blast movement within the orebody are also reviewed, and advancements in accurately measuring these vectors within blasted ore discussed

Sep 26, 2011

By M E. Watson

Minimising dilution and ore loss is an important part of ensuring profitability of a gold mining operation. White Foil open pit gold deposit is a low-grade deposit and therefore managing ore quality is a high priority. Ground movement through blasting can displace ore and waste boundaries up to 10 m from their in situ location and therefore requires stringent ore movement monitoring and adjustment. There are currently only two options for monitoring blast movement – utilising visual targets (commonly lengths of polypipe) but this has widely been replaced by electronic blast movement monitors (or BMM). Regardless of the technology used, the basic principle is to compare the pre- and post-blast locations of the targets to determine the movement of the rock mass during blasting, which is then used to determine the final location of ore and waste boundaries.The Blast Movement Technologies (BMT) BMM system has been used at White Foil since June 2014. The system has been effective and reliable during that time; however, the annual cost of using the BMM system is greater than other monitoring alternatives. As such, the open pit geology team conducted a study comparing the BMM system against the conventional polypipe technique. The objective was to quantify the profit and loss that would occur based on the ore block transformations from both methods. Eight blasts were selected where polypipes were installed in additional holes adjacent to the BMM monitoring holes. The resulting movement vectors from the respective methods were used to create post-blast ore blocks by transforming the in situ ore blocks. While polypipe is a cheaper alternative, the BMM system tracks ore and waste boundaries more effectively resulting in better quality control, enhanced ability to minimise dilution and ore loss thus maximising profit. For these eight blasts, it is calculated that the BMM system resulted in A$664 978 extra profit through a reduction of ore loss. The total cost of a yearly BMM package was recovered in the first two blasts of this study. The primary reason for the difference is that polypipe had a poor recovery rate of 32 per cent compared with 92 per cent for BMM at White Foil. Therefore, the data used to transform the ore blocks was less representative, resulting in inaccurate post-blast ore block boundaries when using polypipe.CITATION:Watson, M E, 2017. Blast movement monitors or polypipe? A study into cost-effective blast movement monitoring at White Foil gold mine, Western Australia, in Proceedings Tenth International Mining Geology Conference 2017, pp 433–440 (The Australasian Institute of Mining and Metallurgy: Melbourne).

Sep 20, 2017

Whilst employed by Dyno Nobel as the Technical Services Engineer û Brisbane, I was asked, as part of a contractual agreement, to look at optimising PioneerÆs blasting process to provide the most effective rock to the new crushing and screening plant. This paper details the preliminary blast designs and practices that have been in use at the quarry and the initial changes made to these designs, and the effect they have had on the excavation and crusher performance.

Jan 1, 1999

By Grobler H. P, Chitombo G. R

Production blasting of Dc Beers Consolidated Mines Limited, Koffiefontein and Finsch Mines involves both uphole trough rings of 9 to I I holes and near vertical 360 degree compound rings of 42-54 holes. The rate of production from these stages is dependent upon being able to achieve a specified fragmentation size range and this has driven the derivation of blasting practices to consistently achieve this target fragmentation. At the Dutoitspan Mine, in Kimberley, where mining of the kimberlite pipe is by block caving, 100 per cent extraction of the undercut level by ring blasting is essential. If this is not achieved, pillars are formed which not only inhibit the efficient initiation of the caving process, but also concentrates load onto the extraction level, causing damage to draw points and pillars. These two case studies demonstrate the importance of achieving optimum blasting performance for downstream mining efficiency; ie fragmentation for increased productivity at Koffiefontein Mine and 100 per cent undercut extraction for efficient initiation of the caving process at the Dutoitspan Mine. The case studies also serve to highlight the long road towards blast optimisation taken by De Beers Consolidated Mines Ltd (Koffiefontein. Finsch, Premier and Kimberley Mines) since 1989.

Jan 1, 1995

By Geoff Baldwin

The use of monitors to assess equipment performance is carried out on a routine basis in many industries. The benefits gained through process control in knowing exactly how the equipment is working far outweigh the initial capital costs of the monitor. In the mining industry several dragline monitors have been developed and installed on equipment through out the world, but to date none has been fully accepted by the industry. This paper describes the use of a sophisticated monitoring system which incorporates an onboard processor to assess both dragline and blast performance. The results of a case study are presented and an indication of the potential of the monitoring system to optimise mine production is given.

Jan 1, 1990

A blast is designed to completely break competent rock such that it can be economically extracted, and efficiently handled or processed. Efficient breakage of the rock is critical to the success of an operation, and in many operations blast design is optimised to achieve fragmentation, muckpile profiles, and material that is easily excavated. There are inevitably other issues, such as damage to adjacent rock, that should be taken into account when designing a blast to achieve overall optimisation. Some of the key issues with respect to the integrity of the in situ materials adjacent to a blast are identified and briefly discussed in this paper. The potential for damage and the effects of a blast will be strongly influenced by the rock mass properties. This makes it important that site specific conditions and their response to blasting are known. Practical techniques that allow the disturbance adjacent to a blast to be measured with minimum disturbance to operations are described in the paper. Experience shows that, during the blasting process, there is considerable potential to disturb the in situ rock mass adjacent to the blast. In some circumstances a very important objective must be to minimise disturbance outside of the immediate blast area. Measured and observed disturbances caused by blasting to adjacent rock, for various common types of blasting, are discussed in this paper. Blast induced disturbances to the rock mass have been observed in both the near and far fields. These disturbances have the potential to impact on geotechnical design. The geotechnical significance of blast disturbance on a rock mass that is to remain in situ is explored and suggestions with respect to design are given.

Jan 1, 2004

Against a background of deeper pits, the introduction of prestripping fleets and the need for closer control of operating costs (especially the waste removal component), Australian coal operations utilising draglines have in recent years become increasingly focused on:1. assessment of more efficient excavation methods; and2. application of explosive products and initiation systems which offer more flexibility than ever before.Additionally, developments in blast performance assessment techniques and equipment, and computer modelling and excavation monitoring systems have provided an improved opportunity to design a blast to achieve a desired profile suited to the excavation equipment and Sequence.

Jan 1, 1992

IN the present paper it is the writer's intention to largely confine the subject-matter to details relating to the metallurgical practice in connection W,ith the blast roasting of lead ores at the Port PiJ;ie works of the Broken Hill Associated Smelters Pty. Ltd. rather than to elaborate on mechanical plant details which are more or less standard equipment of the average Dwight and Lloyd or Huntington-Heberlein blast roasting installations (hereinafter referred to in the text as D. & L. and I.I. & H. respectively). The present blast roasting plant is a combination ot D. & L. straight line machines and IQ-ton H. & H. pots. The latter installation was an operating unit prior to the introduction of the D. & L. machines, the pre-roasting then being accomplished in Ropp roasting furnaces.On the introduction of the D. & L. machines the use of the Ropp roasting furnaces as a pre-roasting unit was discontinued, and this step of the process was then carried out on one section of the D. & L. installation.Consequently, then, the present plant consists of (1) A section of D. & L. machines, which operate solely as a pre-roastiIig unit. (2) A section of D. & L. machines which operate to their full capacity as 3, final roasting unit and treat the main portion of the pre-roasted material.

Jan 1, 1922

By Moore A. J, Evans R

Blast vibration control and assessment techniques have been developed which supplement traditional charge mass scaling methods. The improved techniques, which can be used to predict air and ground vibration levels at the planning stage, and to assist in the control of blasting operations, have reduced the level of operating risk concerning blast vibration. In addition to such factors as charge mass, distance and blast vibration levels, these additional techniques take account of orientation of the blasting face, topographic shielding, wavefront reinforcement, and meteorological conditions. They have assisted in compliance with specified blast vibration levels for environmental licence and mining lease conditions, the reduction of blast vibration nuisance to residents in the area surrounding a mine, and control of building and rock structure response in adjacent areas on the mine lease area.

Jan 1, 1994

By Moore A. J

This paper describes the use of a wavefront reinforcement model which has been developed to supplement established charge mass scaling methods. The model allows for the time taken for blast vibration wavefronts to travel from each blasthole, and has been successfully used to explain the reason for directional increases in both air and ground vibration in certain situations. The model has been used to identify wavefront reinforcement due to the propagation of air vibration and ground vibrations in certain situations. The paper includes a throw (or cast) blasting case history which provides multi-station evidence of the strong directional nature of wavefront reinforcement.

Jan 1, 1995

By Moore A. J

Control of blast vibration requires that its nature and causes be understood, and that effective control procedures be implemented to ensure compliance with limits related to the probability of damage to buildings/structures and human discomfort. This paper covers measurement equipment, assessment and prediction techniques, blast vibration control procedures and applicable statutory limits. It reviews current practice, and provides information on recent developments in blast vibration measurement equipment and control techniques, using examples based on Hunter Valley mining practice.

Jan 1, 1995

During underground mining, rock mass changes can occur as a function of the mining sequence and excavation processes. Mining-induced rock mass damage can occur due to redistribution of static stresses and the application of dynamic stresses from blasting and seismic activity. These rock mass changes can result in a degradation of strength of the bulk rock mass and the remaining rock surrounding existing excavations. Rock mass damage near existing excavations which lead to excavation-scale instabilities such as rock fall, excavation closure, or visible rock mass fracturing can detrimentally affect the safety and profitability of mining operations.The focus of the current work was the prediction and assessment of damage to mine infrastructure occurring in relation to the blasting of a sublevel open stope. The study case involved a 60kt stope located in a highly-competent rock mass at a large Australian sublevel open stoping mine. The mine infrastructure of interest for investigation included local stope access development, critical access and haulage development crossing a regional-scale fault, an explosives storage magazine and a ventilation return air raise. The methods used to predict or assess the blast-induced damage to each infrastructure element in response to stope extraction were:- intact rock strength testing,- discontinuity mapping,- linear-elastic static stress modelling,- blast-damage mapping,- near-field blast vibration monitoring and analysis,- geophysical assessment using inferred stiffness and wave velocity methods, and- post-extraction void assessment.The results of the detailed blast damage prediction and assessment program at the mine site have been discussed by the primary author elsewhere (Fleetwood, 2010). The current work will address blast-induced damage to mine infrastructure as a result of extraneous blasting vibrations from stope production blasting. A method for predicting the amplification of excavation surface motions from reflecting body waves will be discussed as well as the results of damage mapping around the study stope. The results of the damage mapping program identified blast-induced damage that occurred to the surface of the explosives storage magazine and local stope access development. No damage was observed at the main fault crossing or return air raise where higher vibration amplitudes were measured or predicted.

Dec 6, 2010

In order to satisfy environmental and mine operational requirements it is becoming increasingly important to minimise ground blast vibrations at certain locations. These locations are often in soil or on large resonant structures such as grain silos, highway bridges or even the walls of an open pit. A soil monitoring exercise was carried out to evaluate the common practice of coupling vibration detectors to the ground using spikes. At a series of locations in an operating quarry the spiked array response to single blastholes was compared with that of an accelerometer array attached to a calibrated embedded mount. The results clearly showed that the spiked arrays over-estimated the true ground vibration by 46.5 per cent on average, with a maximum observed error of 99.2 per cent. These errors are considered too large for compliance monitoring where accurate vibration levels are required for comparison with prescribed limits. Although spike coupling is convenient, its use for compliance monitoring should be viewed with caution. Unfortunately, however, many manufacturers supply their detectors as spiked arrays. A structural monitoring exercise was also carried out to evaluate the vibration response of a grain silo, highway bridge and a pit wall to the initiation of single blastholes. In this case accelerometers and standard geophones were firmly attached to the bridge which resonated at low frequencies. The results clearly show that, due to their limited low-frequency response, the geophones typically measured only half the true vibration level as measured by the accelerometers.

Jan 1, 1995

Blasthole cone samples are used for grade control in most of the iron ore mines of the Pilbara of Western Australia. This method of sampling is straightforward when the target sampling interval matches the mining bench height but is problematic when the blasted bench is 'flitch' mined in two or more passes. Crucially, the sampler needs to decide which part of the blast cone represents the upper and lower flitches to be mined. This sampling selection decision is usually made by assuming a certain proportion represents the subdrill component of a sampling face in a blasthole cone and the two flitches are split equally from the remaining portion. In this study of a West Australian channel iron deposit, sampling experiments were carried out to determine the actual proportions of a sampling face in a blasthole cone by spray painting the blast cones at flitch and subdrill boundaries during the drilling process. Measurements were then taken to assess the differences between assumed sampling face proportions and actual proportions. A set of paired samples was also collected from a number of blastholes with one set using the assumed proportions of each flitch for each sample, while the other set sampled the actual proportions, which were identified from the cone painting process.

Mar 1, 2010

By Bulters J, Sheppard I

Two blasthole density logging programmes have been conducted on the Mt Whaleback iron ore mine to evaluate the use of this type of logging as an aid to blast pattern design. The first programme also involved the setting up of a Density Test facility with which to calibrate the density probe. The programmes indicated that about 22-23 blastholes can be consistently logged per day at a cost of $1.30 per metre. Even though this is only half the rate required to log the average number of blastholes drilled daily on Mt Whaleback, testwork indicated that no significant loss of accuracy results if only half the holes in a pattern are logged. The major results of the programmes were: 1. The density range for black pyritic Shale is 2.2-2,9 g/cc. 2. The density range for soft to medium hard BIF is 2.1-3.0 g/cc. 3. The density range for hard BIF is 3.0-3.6 g/cc. 4. The front row blastholes show consistently lower densities than the main body holes due to blast damage. 5. A low density zone extending to a maximum depth of 6 m occurs at the top of most blastholes and results from blast damage from the bench above. These density results have been used to implement savings in drilling and blasting via pattern expansion and charge optimisation of blastholes. Eight ore

Jan 1, 1986

A good blasting result is largely achieved by putting the right amount of explosive in the right place and firing it in the right sequence. The best blast design in the world will not break the rock if the planned blast layout is not achieved in the field. One of the critical inputs into a blast design is the diameter of the blasthole. An assumption that the actual blasthole diameter is equal to the nominal drill bit size is generally made. However, a small deviation in the actual hole diameter from that assumed will have a dramatic effect on the hole's volume and, consequently, where the explosive is placed in the blasthole. Any discrepancy in actual blasthole volume from that assumed will be reflected in 'overloading' or 'underloading' of the blasthole with the calculated explosive quantity and, thus, reflect in explosive distribution and stemming lengths. When loading to a 'collar' in an oversized hole extra explosive will be used, resulting in higher than planned powder factors and explosive costs. A blasthole diameter assumed from a nominal drill bit size is an incorrect assumption. This paper will present some actual blasthole diameter measurements illustrating the variation in hole diameters seen in the field and proposes a practical method for achieving a useful blasthole diameter measurement.

Jan 1, 1990

By K H. Esbensen, K Engström

The conclusion from the debate over the last decade in the mining sector is that, for grade control, reverse circulation (RC) drill sampling gives more reliable results due to less sampling problems than blasthole samples. However, by conducting the latter with well-controlled procedures there still exist fair possibilities to counteract the major blasthole sampling problems and achieve fit-for-purpose representativeness, especially if based on minimal loss of fines. In the present PhD study, extensive replicate experiments and variographic characterisations are conducted to evaluate the performance of manual blasthole (BH) sampling and sectorial segment sampling. The experiments were performed in Luossavaara-Kiirunavaara AB (LKAB)’s Leveäniemi open pit mine in the north of Sweden. The experimental area is an apatite-magnetite iron ore deposit of the Kiruna type, with the demand to exhibit a maximum of local heterogeneity to allow the experiment the largest possible conclusion powers. Gathering and splitting the complete BH drill cutting cones (fines cone, coarse cone) served as an authoritative reference on which to assess the representativity of the two BH sampling methods.Results show that manual BH drill sampling is able to produce samples with an acceptable accuracy and precision if performed properly and with insight. Based on variographic comparison, segment sampling shows similar precision for chemical grades as the manual sampling, while the particle size distributions were more deviating for segment sampling than for manual sampling at the high and low size ranges. Possible reasons for these partly surprising results are discussed.For further investigation of the performance of BH versus RC drill sampling, a second experiment has been planned on a parallel profile. This will result in an unprecedented opportunity for a full variographic comparison between RC and BH sampling, aimed at designing specific, fit-for-purpose sampling procedures as a function of ore quality, cut-off grades and important contaminant levels.CITATION:Engström, K and Esbensen, K H, 2017. Blasthole sampling (replicate and variographic experiments) in LKAB open pit iron ore mines – fit-for-purpose representativity?, Australia, in Proceedings Eighth World Conference on Sampling and Blending , pp 85–96 (The Australasian Institute of Mining and Metallurgy: Melbourne).

May 9, 2017

Conventional blasthole sampling for grade control has acquired an extremely bad reputation for the last 50 years. The introduction of many sources of bias is a structural reality. Delimitation biases are devastating. Extraction biases are of great concern as well. Weighting biases aggravate an already bad situation. Furthermore, preparation biases are many. Some of these biases are due to the type of drilling machine that is used and are nearly unsolvable. Some of these biases are due to the sampling tools that are used and often unsatisfactory. Attempts to automate blasthole sampling at the drilling site have failed, not because it cannot be done, but mainly because it interferes with drilling productivity. As a result the miner most often rejects the idea after a few weeks of practice. Manual sampling of blasthole piles is a disaster for many reasons; some are related to the methodology, some to the selected sampling protocol, some to the training of operators, some to limited manpower available, and some to limited supervision. Furthermore, with blasthole sampling a time logistic problem is unsolvable as the miner wants the ore grade control geologist to make up his mind within two or three days at most; as a result not enough time is allowed for samplers, preparation facilities, laboratory, and resources department to perform a good job as everyone is working under unreasonable pressure. The economic impact of poor blasthole sampling for grade control has been vastly underestimated by mining companies. The resulting ore grade misclassification is responsible for severe reconciliation problems and massive financial losses every year. This paper suggests areas along this grim scenario where things can be greatly improved; however it is clear that too many problems are unsolvable. An alternative using reverse circulation drilling for grade control is suggested. A thorough analysis of the respective advantages and disadvantages for blasthole and reverse circulation drilling for grade control is presented in this paper.

Jan 1, 2008

By Hyde L. J

Blasting is one of the available technologies to be employed in underground excavation systems. In many instances it can be the only technology which is suitable. The recent moves towards more mechanised working systems is resulting in a reduced awareness of new blasting practices and technologies on the part of many excavation engineers. Recent developments in blasting systems can be utilised to significantly improve operating efficiency, reduce total cycle times, better comply with regional environmental constraints and reduce the total cost of underground excavation. Blasting is and will remain, a very adaptable and exciting alternative which is far from boring.

Jan 1, 1987