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By D Moy, T Carter

This paper outlines the feasibility assessment conducted to explore the possibility of constructing two submarine water supply pipelines beneath the Ma Wan Channel in Hong Kong using either horizontal directional drilling or tunnelling. The Ma Wan Channel is a major shipping channel in the Northwest New Territories, which separates Ma Wan Island from the mainland. The challenges faced by the projectÆs designers included space limitations on either side of the channel, marine department restrictions on construction activity within the channel and selection of a suitable crossing alignment and profile given the channelÆs depth, irregular sea floor topography and complex geology. The existing geological information indicated the proposed alignment would cross granitic and volcanic formations, which would likely be faulted. The primary concerns with horizontal directional drilling were:the length, diameter and depth of the crossing were at the limit of precedent experience in rock; the lack of available space at both the entry and exit sites; and whether the technique would be flexible enough to cope with the anticipated range of ground conditions. The primary concerns for tunnelling were: the possibility of encountering large inflows of high pressure groundwater; andthe possibility of encountering disturbed ground within the fault zones which could flow if not properly treated. As a means to evaluate and mitigate these technical risks for both construction options, a directionally drilled pilot hole was used to investigate the ground conditions along the proposed pipeline alignment. The pilot hole results indicated that either directional drilling or a closed face TBM drive were technically feasible crossing options at a crossing depth of 80 m. The results also indicated that either an open face TBM or a drill blast drive would need to be constructed at much greater depth because of the presence of highly permeable, disturbed ground in mid-channel at this crossing elevation.

Jan 1, 1999

By E Amini, N Beaton

Application of ore pre-treatment technologies such as Grade Engineering and in-pit ore treatment require comprehensive analysis to show proven value is being generated by switching away from the current practices. Considering most mining operations last several decades; the pre-treatment technologies must be investigated over life of mine (LOM) to truly show value was generated or lost. Therefore, a value chain flowsheet model has been usually developed to run those analysis/simulations over LOM using a set of defined ore characteristics and the operating equipment capacities. The Integrated Extraction Simulator (IES) has been used for this type of LOM simulations as it has the necessary flexibility to accommodate the whole mining value chain flowsheet in one platform and provide essential computation power to run mass simulations for the given scenarios using the resource block model. This allows to forecast the value chain response over the LOM for all given scenarios in a feasible amount of time. The traditionally developed flowsheets for the analysis/simulations are usually limited to the mineral processing plant and were developed based on a single audit conducted on the plant in a very short time, e.g. several hours. The process plant is being operated with a certain ore at a certain condition during the short audits which would not reveal the true capacity of the operation equipment when ore characteristics changes. Therefore, it would be impossible to define the true capacity of the equipment and identify the constraints along the value chain. In this study, a methodology was developed to identify the constraints along the value chain and implement those in the IES flowsheet using process information. Also, the equipment models were fine-tuned to represent the true capacity of the equipment in the flowsheet using the same data set. The methodology was tested over five process plant in two operations and showed the performance forecast was significantly improved over the traditional methods being used so far. Then those high-fidelity flowsheets were used to evaluate the ore pre-treatment technologies proposed by the relevant resource company experts.

Nov 10, 2020

By Watsford RMS, Schache IS, Slaughter PJ

As part of the overall Copper Smelter expansion activities at Mount Isa Mines from 1970 - 1975, a decision was made to open circuit the converter slag from the Smelter and treat this product by flotation. This paper describes the technical aspects of plant operating and reagent practices employed, with particular emphasis on the large scale milling of this product and the effect through the use of reagent hydroxy ethyl cellulose on chalcocite grade and recovery.

Jan 1, 1978

By B Newcombe

From many years practical industrial experience the author has drawn together a list of the key points to consider when embarking on a large-scale geometallurgical project. Fundamental aspects which must be considered include (but are not limited to):understanding the variability of the orebody both laterally and with depth;comminution properties and variability;flotation properties, requirements and variability – differing ore zones may have substantially different requirements for optimal performance;the role of texture – the consequences of both grain size and distribution and how the circuit will handle these;realistic expectation in terms of the financial requirements and time frame results are required within; andintegration of, and communication between key personnel within the various departments of the site (mining, geology and processing) is a fundamental aspect of any geometallurgically based processing system. An example of a highly complex nickel sulfide ore will be used as the basis of discussion.

Sep 5, 2011

By A Mooney, J Marsden, H Grosser, G Dunstan

Carrapateena is a copper-gold deposit hosted in a brecciated granite complex, located 500km North of Adelaide, South Australia. The deposit is being mined using the Sub Level Caving (SLC) Mining method at a rate of 4.25 MTPA. The Carrapateena SLC construction was completed in Q4 2019, with ramp up to a mine production rate of 4.25 MTPA completed within 12 months; ~ 6 months earlier than originally planned (OZ Minerals, 2020b). Traditional SLC designs have had issues with safety interactions on production levels, namely at the perimeter drive, as well as presented challenges for the application of automation due to frequency of activity required to achieve ring turnover rates. Safety in design provides an opportunity to learn from experience at recent modern SLC operations and by considering hazards early in the design process minimise exposure and improve safety, productivity and automation of mining activity. This paper discusses the work carried out during the Carrapateena feasibility study and optimised during project execution; to update the SLC production level mine design, with a layout known as the Carrapateena Crows Foot Level Layout. This paper focuses on: • An introduction to the Carrapateena Operation and mine plan. • An overview and historical challenges of traditional level layout. • An introduction to the Carrapateena Crows Foot level layout, including production level design parameters as well as development metres and productivity comparisons. • Outlines the benefits of the Crows Foot design for safety in design of SLC operations. Provides a roadmap for improved production efficiency, level operational philosophy and the application of automation within the SLC.

Mar 15, 2021

By G Campbell-Cowan

Much has been written about the fact that most transformation efforts disappoint. This paper addresses factors that should be taken into consideration in planning and implementing transformation programs to ensure success.In 2009, St Barbara commenced a transformation program to address issues of chronic poor quarterly operational performance; financial pressure caused by the unreliable operational performance; and an inability to develop business plans with integrity and to reliably deliver on the plans. As a result of a number of years of disappointing operational performance, St BarbaraÆs culture was not conducive to business success.This paper uses lessons learnt during St BarbaraÆs transformation program to highlight key characteristics of change programs that can generate significant sustainable benefits. While there were many benefits from the transformation program, the most significant impacts of St BarbaraÆs program have been transformation of the companyÆs culture and capability of people as business leaders; the establishment of a business systems framework to guide the design and development of systems; and developing support functions, for example centralised procurement and supply chain, business improvement and technical services.CITATION:Campbell-Cowan, G, 2012. Business transformation - Lessons learnt for successful change, in Proceedings International Mine Management 2012, pp 135-142 (The Australasian Institute of Mining and Metallurgy: Melbourne).

Nov 20, 2012

By E Kabwe, M Karakus

Deep hard rock underground mines tend to experience high stress as such drives exhibit dynamic responses attributed to a rock burst variant (strainburst). This dynamic behaviour is difficult to predict, and every effort is made to devise the appropriate dynamic support system for its associated failure restraint. This paper outlines the back analysis and the support scheme design for an underground decline that exhibited damage from a dynamic strainburst occurrence. It employs a decline section that experienced a dynamically loaded strainburst that initiated rock fragment ejections. The procedure involves a preliminary structural analysis, a seismic intensity measure, and a rock mass simulation to determine the static stress concentration and ground support system response. The numerical simulation is conducted in FLAC3D which employs the advanced strain-softening IMASS constitutive model governed by two Hoek–Brown (HB) bounding yield surfaces. To account for the post-peak brittleness response associated with strainburst the plastic strain multiplier () is adjusted to 0.0 < < 1.0. The back-analysis shows that the occurrence was initiated by a low-intensity seismic wave that superimposed an extra stress component to the initial static stress which triggered rock fragment ejections. Additionally, the appropriate support scheme comprised of Weldmesh, Fibrecrete, static (split set) and yieldable (Kinloc) reinforcements is recommended and implemented. Thereafter, the bolt’s efficiency is evaluated based on the axial force and elongation capacities and then compared with the published bolt performance data. The evaluation results show that the maximum bolt axial force (0.1 per cent) and elongation (0.006 per cent) are below the designed capacity and rupture strain.

Nov 29, 2022

The information age has arrived. In every aspect of life, at the end of the second millennium, computers and information technology have made significant inroads. In mining there has been huge growth in the use of digitally controlled systems. From resource evaluation to mine planning to daily operations, information is being acquired, analysed, modeled and presented, using state-of-the-art information technology. Explosives, too, have moved into the information age. Computer controlled trucks and manufacturing plants have been developed and are now a regular feature on many mine benches. The next challenge for the explosives industry as a whole is to integrate blast initiation with information technology. The benefits are there, both to the supplier and to the end-user. Much has been written in the past about the potential for blast improvement but there are other significant advantages to a digital initiation system. These include security from unauthorised use, stock control and minimisation, reliability through testability and ease of use to name a few. So why is it taking so long? Surely the complexity of an electronic initiation system is far less than that of mobile phones that have been around for a long time. The answer, it seems, lies in the level of new technologies that need to be developed. There are enormous technological hurdles to be overcome in order to put into the market a cost-effective, reliable, user-friendly electronic initiation system. The most significant of these are:Safely and reliably initiating an explosive from an electronic device powered by a small capacitor. Prior to the development of electronic detonators primary initiation of explosives was by shock tube spit or by passing large currents and voltages down a pair of wires. Electronic detonators do not have that luxury. For example the energy stored in a æBeethovenÆ exploder is more than 500 times greater than that available to an electronic detonator. Communicating to a multitude of devices over very long cables installed by miners in harsh conditions. The deployment of an electronic detonator system has been likened to building a large telephone exchange in the rain and getting it to work perfectly first time! New communications protocols needed to be developed and tested. Wiring and connection systems have to be designed to survive the mining environment. In spite of these technological hurdles most of the major explosives manufacturers have persisted with electronic initiation systems and we are now, in 1999, starting to see the results of these multi-million dollar efforts. At SMI we are often asked many questions about this technology. The remainder of this paper seeks to answer those most often asked. As with any business linked to information technology todayÆs breaking news is tomorrowÆs archive and we expect the rate of development and understanding to accelerate as these technologies become accepted by the global mining industry.

Jan 1, 1999

By C Vejrazka1

The occurrence of airblasts is one of the principal mining hazards in caving operations between the time of cave establishment and breakthrough of the cave to surface. As such, it needs to be managed continuously and risk assessments need to be reviewed on a regular basis for applicability to changing conditions. The likelihood of an airblast occurring is based on a range of geotechnical factors over some of which engineers on-site only have limited control. However, the impact of an airblast to the underground mine, if it does occur, can be managed by following established safety guidelines for the production from the cave.This paper outlines how the Caving Airblast Simulation Tool in Ventsim was used to determine a risk management strategy for a sublevel and a block cave at a mining operation in Australia. The block cave has a footprint of 14 500 m2 with the extraction level located 1250 m below surface while the sublevel cave currently has a footprint of around 18 000 m2 operating between 660 m and 800 m below surface. Both caves are currently in their early operational periods. The risk analysis provided valuable information for the production planning of the caves including confirmation of extraction ratios for the block cave undercut, locations of airblast walls and maximum allowable air gaps for different muck pile heights to ensure safe operation is achieved.

Oct 12, 2022

The demands of the economy require larger manufacturing facilities using greater quantit- ies of raw materials which must be mined, handl- ed, stockpiled and recovered with efficiency and dependability. All over the world, mining com- panies, steel manufacturers, power stations and process plants are not only seeking but finding methods of increasing outputs and&apos;reducing costs in the field of materials handling. In mining bigger continuous mining machines and shovels, larger trucks and crushers are digging and processing greater quantities of differing materials which have to be handled and shipped at rates once thought to be impossible. To implement such schemes demands the blending of a lot of diverse-equipment, mining machinery, bins, feeders, reclaimers and it is here that the belt conveyor assumes a role of ever increas- ing importance. Significant developments have taken place in the seventies with respect to conveyor belt transportation; not only in the systems but also in the components which combine to make such systems work efficiently.

Jan 1, 1976

By K Jupp, T J. Howard

Cliffs Natural Resources Pty Ltd (CNR) operates iron ore mines in the Koolyanobbing region of Western Australia, about 50 km north of the town of Southern Cross. Ore is trucked from three geographically isolated sources to the crusher at Koolyanobbing, where it is blended before and during crushing. Lump and fines products are produced and railed to Esperance for ship loading and export to Asian customers. CNR is examining alternative processing paths, from mining to ship loading, with the aim of improving efficiency and reducing costs. Modifications to the system must be consistent with potential future expansions and maintain the low inter-shipment grade variability on which CNR prides itself and has built a strong relationship with its customers. In searching for the optimum process design, many options from mine face to ship loading must be evaluated and compared. Pilot plant studies are infeasible, while complex mineralogical interactions, competing goals and numerous possible system configurations limit the applicability of theoretical analysis. It was therefore concluded that simulation modeling would provide the confidence to take the next step into production trials. This paper describes techniques applied at CNR to simulate grade variability resulting from potential process design changes. The simulation models are easily run Excel-based modules, with each module representing a different part of the process. The modules use extensive Visual Basic macros driven by Excel&apos;s user-friendly interfaces. Presentation of the results is enhanced by Excel&apos;s excellent graphical capabilities. The simulation software stores and graphically presents time-stamped data from a run, enabling detailed analysis of different process configurations. Final success of a simulation run is measured by inter-shipment variability (standard deviation and process capability) and in-process ore tonnages. Meaningful results from the simulations require the initial input data contain the same correlations present in the real production environment, between the mineral components, production linkages and across time. The data also have to allow simulation of potential changes to mining method and introduction of new pits into the blend. Mining data from the real operations under study are therefore used, with average grades and variability adjusted to match potential future development proposals. It is also necessary to filter out medium and long-term variations from the production data as this variability is best controlled through the conventional medium to long-term mine planning process, not by the process design being studied. The filtering was carried out using a Fourier transform technique, which is described.

Jan 1, 2009

By G R. Hancock, M J. Saynor, J B. C Lowry, K G. Evans, M Narayan

Tools such as landform evolution models (LEMs) provide a means of predicting how a landform may evolve over extended periods of time. Here, we utilise the CAESAR-Lisflood LEM to assess a proposed rehabilitated landform of the Ranger Uranium Mine in the Northern Territory of Australia (Figure 1). The environmental requirements for the closure of the mine state that the final landform must be able to physically isolate tailings material from the environment for a period of at least 10,000 years (Australian Government, 1999). However, uncertainty exists as to the reliability of model predictions representing thousands of years.In this study, we use model predictions from an undisturbed pre-mine landform to calibrate the parameters used in model simulations of a post-mining rehabilitated landform over a simulated period of 1,000 years. Specifically, we vary environmental conditions such as rainfall, presence/absence of vegetation and surface particle size characteristics in a series of model simulations to determine their impact on the respective landforms, to revise model input parameters as required. A simulated period of 1,000 years was used as it represents a period in which long term landform evolution patterns and trends may be established and identified. CITATION:Lowry, J B C, Narayan, M, Evans, K G, Saynor, M J and Hancock, G R, 2018. Using an undisturbed landform to calibrate long-term predictions of the evolution of a rehabilitated landform, in Proceedings Life-of-Mine 2018, pp 133–137 (The Australasian Institute of Mining and Metallurgy: Melbourne).

Jul 25, 2018

University education in Australia is changing, driven by greater market orientation, reduced funding available per student, especially in the higher-cost minerals industry disciplines, and the call for more flexible delivery of subjects and courses to meet changing lifestyles and expectations. The opportunity exists for a true partnership to develop between industry, government and academia that will reshape minerals education in Australia and secure the future supply of the specialists industry needs to maintain international competitiveness. If this partnership does not emerge, it is anticipated that AustraliaÆs somewhat fragmented and unstable higher education system, especially in the disciplines of particular relevance to the minerals industry, will be put under further pressure so decreasing its effectiveness to produce quality graduates. The Minerals Council of Australia in 1998 published æBack from the BrinkÆ, a discussion paper which proposed strategies to build a world class minerals tertiary education system in Australia. Those strategies are now being implemented collaboratively with principal emphasis on the disciplines of mining engineering, metallurgy and earth science and as far as process is concerned, on the necessity to æcooperate to competeÆ. For metallurgy, the challenge is to integrate more closely undergraduate teaching with the existing world-class research centres and to link the tertiary institutions in such a manner that the strengths of all components are harnessed and then made available nationally in major population centres and at remote sites where appropriate. For industry the challenge is to build effective partnerships with the academic community that will enable and assist the agreed course of action to take place.

Jan 1, 2000

By T Amiconi

Ernest Henry Mining commenced operations on its copper-gold project in August 1997, some two months ahead of schedule and ten per cent ($35 million) under budget. The mine is located in the highly prospective Mount Isa/Cloncurry mineral district in north-west Queensland, approximately 38 km north-east of Cloncurry. The developer and operator of the project is Ernest Henry Mining Pty Ltd (EHM), an incorporated joint venture between MIM Holdings Limited (51 per cent) and Savage Resources Limited (49 per cent). The deposit is located approximately 40 km north of Cloncurry in North West Queensland and lies beneath a featureless black soil plain with no significant creeks or gullies cutting across the site. Vegetation is sparse and consists essentially of Mitchell grass with occasional low shrubs and trees. Up to nine million tonnes of ore and over 43 million tonnes of waste will be extracted each year from an open pit operation to produce approximately 350 000 tonnes of concentrate when in full production.

Jan 1, 1998

By J Johansson, B Johansson

The mining industry needs to attract and recruit young talented people. An important task is, therefore, to create an attractive mining workplace that engages with, and motivates youngsters who are not particularly interested in working in the industry. This paper aims to illustrate a way forward for the mining industry to form healthy and safe workplaces honouring key components such as knowledge, skill, co-operation, continual development and acceptance of diversity. This is a way to create a vision of healthy and safe mining work. The mining industry must work towards zero vision; a future without accidents and hazardous environments. In this paper the authors discuss different aspects of an ‘attractive workplace’ and summarises lessons learnt in 26 statements dealing with safety, both physical and social work environments, and social responsibility. The authors hope these recommendations will provide some guidance for how attractive workplaces should be designed for future deep mining.The paper is based on lessons from two large European projects, a Swedish-Polish project: The Smart Mine of the Future; and a European Union project: Sustainable Intelligent Mining Systems (SIMS). One of the authors was the WP leader of health and safety in both projects.CITATION:Johansson, J and Johansson, B, 2017. Attractive workplaces in future underground mining, in Proceedings 13th AusIMM Underground Operators’ Conference 2017, pp 99–102 (The Australasian Institute of Mining and Metallurgy: Melbourne).

Oct 16, 2017

By F D Durao, Muge F. H, Rogado J. Q

In the scope of the project named CAPUME II (EEC BRITE/EURAM contract - project MA2M-CT90,-0042(SMA)) for the development of an integrated mine planning system for underground mines, two of the main tasks were the development of a short-term mining planning procedure (module) and a numerical simulator of the mineral processing plant of Pirites Alentejanas - PA. The short-term mining planning module defines the mining sequences by solving a constrained minimisation problem. The ore grade variability is the objective function subject to the geometrical constraints of the mining method and to the maximum of `internal blending&apos;. The optimisation problem is solved by applying a dynamic programming algorithm. The plant simulator is an essential tool of the planning system allowing the preview of metal grades/recoveries of copper, lead and zinc of concentrates streams, given the corresponding metal assays of the run-of-mine ore, defined by the short-term mine planning module. This way, the management can plan the short-term mining operations (the weekly sequence of exploration blocks and the internal planning) in order to fulfill given required conditions, based on a shipment schedule and on a purchaser&apos;s formula. In this paper, after a short description of the short-term mining planning module and of the simulation package named SIMUL, a synthesis of the main model development steps and the results of some simulation runs are presented and discussed.

Jan 1, 1995

By R Lachenicht, J Player, A Thompson, E Villaescusa

Kanowna Belle Gold Mine is a deep, high-stress, sublevel open stoping mine located near Kalgoorlie. Seismic activity during the development cycle presented problems, including concerns regarding the exposure of personnel. A number of seismic management systems were developed and tested to monitor seismicity and control the risk. It was recognised that a dynamically capable reinforcement and support system was required to be installed as part of the development cycle to reduce the risk of exposure of the underground workforce to uncontrolled movement of rock. The performance of a new Garford Dynamically capable bolt was measured in tests performed by the Western Australian School of Mines (WASM) at their Kalgoorlie Dynamic Test Facility. Detailed descriptions of the facility and data processing were reported by Player, Villaescusa and Thompson (2004) and Thompson, Villaescusa and Player (2004). The development of the Garford Dynamic bolt is described and dynamic testing results are presented and evaluated. This bolt was implemented in the mining cycle following the testing program; the observed performance is described and assessed in this paper. &nbsp;

Jan 1, 2008

By B Besa

Australia is a world leader in the design and operation of mines accessed by the decline method. Literature indicates that a number of metalliferous underground mines using the decline system are also increasing steadily. This increase has generated a great deal of interest in underground haulage systems in future due to the huge costs involved in the development of declines. Studies have also shown that the current method of accessing orebodies by the conventional decline method has proved to be expensive, especially for narrow vein deposits. This is because decline development costs are influenced by mine planning and design parameters as well as available haulage systems that the mining engineer can choose from. The current access method suggests that more waste material is being extracted because of the size of decline openings adopted (5.5 mW and 5.5 mH). Also the conventional 1:7 decline gradient and turning radius of 20 m makes decline lengths, as well as the duration of development, excessively longer. This paper discusses results of a mine design case study with monorail technology as a method of accessing and developing the decline. The proposed system is economical, has high advance rates and offers a significant reduction in capital expenditure. The study compares costs, development metres and the duration of decline development using the monorail system with the conventional (truck haulage) access method. Results obtained indicate that the monorail technology has the potential to reduce the decline length by over 62.6 per cent and decline costs by 63 per cent for the case study. The monorail system also reduces the total capital development costs by 22 per cent for the same case study. Due to rapid development resulting from increased advance rates and the shorter decline length coupled with smaller decline openings, the time to access the deposit reduced by 71.8 per cent. This case study demonstrates that the economics of narrow vein deposits can be improved significantly by using the monorail system of decline development.

Jan 1, 2008

By D R. Seaman, Y Peng, F Burns, D J. Bradshaw

Telfer Gold Mine is a gold-copper mine in the eastern Pilbara of Western Australia, owned and operated by Newcrest Mining Limited. TelferÆs ores are processed by a dual train, 21 Mt/a, concentrator where gold is primarily recovered by gravity concentration and the flotation of a gold-bearing copper concentrate. A minor portion of TelferÆs gold is also recovered to a pyrite concentrate that undergoes treatment via carbon-in-leach (CIL) cyanidation. The gold recovery of the CIL circuit is below the industry standard and operates with a high reagent consumption rate.With a new fine-grinding facility, the Telfer process plant will have the ability to liberate copper and gold from the pyrite concentrate and recover these by flotation prior to the existing leaching circuit. This process will improve overall gold and copper extraction, while reducing reagent consumption in the CIL circuit.This article is an overview of the development of this methodology. Size-by-size analysis and mineralogical studies of monthly composites identified factors limiting the CIL gold recovery and the causes of high reagent consumption. Laboratory studies confirmed a relationship between the regrind product size and gold leach recovery. The addition of an intermediate flotation stage ensured that the regrind circuit will improve overall recovery while at the same time reducing operating costs. Without the addition of a flotation stage, the additional reagent consumption from regrinding alone would be prohibitive towards increasing recovery. Pilot scale studies confirmed the conditions required to selectively recover gold and copper from the pyrite concentrate as well as establishing the full scale regrinding energy requirements. Construction of this facility at Telfer is currently underway.CITATION:Burns, F, Seaman, D R, Peng, Y and Bradshaw, D J, 2012. Development of a pyrite regrind circuit at Telfer Gold Mine, in Proceedings 11th AusIMM Mill OperatorsÆ Conference, pp 45-52 (The Australasian Institute of Mining and Metallurgy: Melbourne).

Oct 29, 2012

By M Bilodeau, G Caro, R Beaudoin, D Labrie

In 2005, Dyno Nobel Canada Inc, DynoConsult and CANMET-MMSL used their pool of expertise in blasting, ground control, open pit and underground mining, mineral processing, information technology and applied mineralogy to launch a research project aimed at evaluating the role of electronic detonators in the development of a sustainable energy-efficient rock reduction process. The overall objectives were to improve health and safety in a mining environment and reduce energy consumption and greenhouse gas (GHG) production in the Canadian mining industry. The study was conducted in a quarry located in Nova Scotia, Canada, with the objective of taking advantage of the higher accuracy and flexibility of electronic detonators towards improving blast efficiency and measuring its impact on productivity in a quarry environment and energy savings. Optimising the blast sequence was the first aspect to be considered before starting to look at designing bigger blasts and achieving productivity improvements, without creating additional environmental concerns, as the quarryÆs location was representing a challenge in itself in the surrounding community. The use of high-speed cameras (500 fps) was an improved means of analysing blast dynamics during the firing sequence. Seismic monitoring and linear superposition techniques were also applied to validate the sequences to be tested in all three specific geological areas. The combination of field measurements allowed to identify the optimal blasting sequences that would then be delivered accurately with the electronic initiation systems. The data from 12 blasts (six with electronic detonators and six with pyrotechnic detonators) carried out in three different geological formations (soft, medium and hard rock) showed that the electronic blasting technology could increase rock fragmentation by 15 to 20 per cent. A more uniform distribution of rock fragment size was also obtained. Blast improvements on downstream processes resulted in a five per cent productivity increase in rock excavation and transportation, a ten per cent energy reduction in primary crushing and a 15 per cent increase in the primary crusher throughput. A prototype soft-sensor based on primary crusher data (eg energy consumption, throughput, feed and product size distribution) and a simplified computer process model were developed for online measurement of a rock operating work index. Furthermore, rock samples were collected and specimens were prepared in order to determine the tensile and compressive strength of the rock materials, evaluate the aggregate crushing work index and examine the development of micro and macro-fractures under binocular and scanning electron microscopy (SEM). Blast-induced rock damage was evaluated at the end of the laboratory testing program. A reduction in rock hardness by about 30 per cent was observed after blasting. However, the impact of the blasting method (eg using electronic versus pyrotechnic detonators) on the induced rock damage was either absent or not perceptible within the measurement technique accuracy and the number of samples analysed.

Jan 1, 2007