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Coeur d'Alene Mines is a precious metals producer which is dedi- cated to growth through it's exploration and acquisitions efforts. We foster and support these activities by providing our staff with long-term financial support, the encouragement to proceed with their projects and ideas, and a firm belief that we will be successful. Coeur's corporate headquarters are located in beautiful, historic Coeur d'Alene, Idaho. Our main mining operations are Rochester, locate near Lovelock, Nevada, Coeur Mine,located near Wallace, Idaho, and Thunder Mountain, located in central Idaho. Our Ken- sington Gold project is located about 45 miles north of Juneau in southeast Alaska. We have exploration offices located in Reno, Nevada, and Santiago, Chile. At this time, Coeurd'Alene Mines produces precious metals from mines located in the United States. Our Rochester open-pit opera- tion, which is 100 per cent owned and operated, is located in Nevada. Presently, this operation produces 5.5 to 6 million ounces of silver per year and 60-70,000 ounces of gold. We move 65,000 to 70,000 tons of rock per day of which about 23,000 tons is ore. The ore is crushed, stacked on permanent heaps and leached. The recovery is by Merrill-Crowe. Although the average grade is rela- tively low, 1.4 ounces per ton silver and 0.012 ounces per ton Au, the operation is very low cost. Our cost of production is less than $4.00 per silver equivalent ounce. Rochester is anunusual operation in that the crushed rock stacks without much compaction and the ores are easily leached. The final height on our heaps will be about 220', and overall recovery will be about 55 per cent of the silver and about 85 per cent of the gold. Reserves at Rochester are expanding and are now adequate for at least fifteen years of opera- Tion.

Jan 1, 1991

By G Bickert

Australia is currently developing and engineering a range of specialised processing options for rare earth (RE) (Lynas, 2011, Alkane, 2005), zirconia (Alkane, 2005), lithium (Galaxy Resources, 2008) and other special minerals and metals required in high-tech applications. The processing of lithium, zirconium and RE minerals is based on complex leaching processes which require extensive liquor clarification, solid liquid separation and solids washing. The filtration properties for those leach liquors, residues and precipitates are not well understood and differ drastically according to the process route applied. Thus, filtration test work is essential for equipment selection, sizing and design. Similar types of slurries are filtered in laterite nickel, TiO2 and other chemical oriented processes, while more experience is available here as those processes are applied widely for a number of decades. The increasing need for dry stacking of tailings requires advanced tailings filtration with properties differing drastically depending on tailings properties. More traditional mineral processes such as flotation commonly apply filtration. All of these and other cases require proper filtration test work particularly evaluation of vacuum versus pressure filtration and the need for cake pressing and/or air blowing for filter presses. Bench scale test work and/or pilot plant operation is common to determine filtration rates, achievable cake moisture and wash efficiencies and sometimes filtrate clarity. While those values are important, there is much more valid information to be obtained by filtration test work.This paper discusses the intricacy of filter selection and sizing based on driving forces (vacuum and pressure air, compression by mechanical means and slurry) and parameters (cake thickness, forces and times) and different processes utilised in common filtration equipment. It will discuss the in’s and out’s of filtration test work design, planning, and in particular data gathering, processing, reporting, evaluation and filter sizing from recent examples of bench and pilot scale filtration test work for above applications together with methods for predicting filtration performance for example where test work is lacking. One focus will be the realistic extrapolation of test work results towards different parameters utilised in full scale equipment and plants. The conclusion of the paper will contain checklist for filtration test work.

Aug 8, 2011

By M Doran

The Olympic Dam mine utilises 1.1 m to 1.4 m diameter raise bores for generating the initial slot void for most production stopes. Slot raise bores generally span two development levels ranging from 30 m to 50 m in height. Raise bores are reamed upward and typically leave a cap of rock equivalent to two times the raise bore diameter on the drill level (minimum 3 m). This provides safe access over the cap for subsequent production activities. It is therefore critical to ensure robust falling object protection for personnel accessing underneath, and in the vicinity of the raise bore void on the lower level. Recently, a number of mesh failures have occurred at Olympic Dam as a result of falling rock from the underside of the cap and raise walls. In addition, as Olympic Dam transitions to deeper and more challenging ground conditions, rockfall-off onto the raise bore protection mesh is anticipated to increase in frequency. This paper discusses the evolution of raise bore protection mesh used at Olympic Dam and presents results from recent site-based drop testing. This impact testing was carried out using a built for purpose object to replicate point loading and shear failure of mesh wires. Testing was also carried out on an improved mesh design which utilises two layers of Geobrugg high-tensile MINAX mesh. Results from the drop testing suggest an improvement in performance of the raise bore protection mesh is realised with the updated design.

Mar 29, 2023

Mt Muro was a gold and silver mine in Central Kalimantan on the Island of Borneo, Indonesia. Aurora Gold through its Indonesian subsidiary Indo Muro Kencana owned the project. Processing commenced in November 1994, and ceased in June 2002. Mining, including prestripping, commenced in March 1994, and ceased in May 2002. Nominal throughput was 1.5 Mtpa, at average grades of 3.80 g/t Au and 99 g/t Ag. From the start of prestripping until the end of 1996, Drill Blast sampling was the main grade control method. After several studies into the viability of Reverse Circulation, including an assessment of costs and benefits, the switch from Drill Blast to Reverse Circulation was made in late-1996. From 1997 until the end of the project Reverse Circulation was the main grade control method. The mine-to-mill call factors û the reconciliation between predicted and actual tonnes and grades delivered to the mill û for the period from commencement of processing to December 1996 were 1.069 for tonnes, 0.949 for gold, and 0.969 for silver. The mine-to-mill call factors between January 1997 and June 2002 (excluding a period of significant illegal mining) are 1.086 for tonnes, 0.977 for gold and 1.025 for silver. At face value this indicates a 2.8 per cent absolute improvement for gold, and 5.6 per cent for silver. Using average grades for the project, an additional 5112 oz of gold, and 267 173 oz of silver were delivered annually to the mill using Reverse Circulation sampling instead of Drill Blast sampling. The additional recovered metal value is estimated at $US 2.87 M annually, significantly exceeding the cost of Reverse Circulation drilling. This paper discusses a number of issues that may affect the estimated benefits.

Jan 1, 2003

By K Clode, J Al-Shdifat, S Daykin

Planning for a circular economy allows for previously untapped market opportunities to be explored, resulting in new, innovative revenue generating opportunities, while also reducing environmental impacts. In particular, rare earth elements (REE) are in rising demand as they are key components of over 200 products across a wide range of applications (Xie et al, 2023) including renewable energy technologies. There is a geographical disparity in deposits, with China being the top producer, generating 70 per cent of global production in 2022 (Laboure, 2023). This single dominating source has created supply chain concentration and hence supply risks for other nations, providing a driver for finding alternative sources, such as mine-influenced water (MIW) and tailings. In this study, Isle presents a robust due diligence methodology for undertaking a global horizon scan into REE recovery technology, for a large mining company, from tailings decant water on a specific site. Previous studies of the tailings decant water at this site had shown potentially significant concentrations of both heavy and light REE, but challenges such as high flow, very low pH and high concentrations of iron had previously made recovery unfeasible. Due to these challenges, the horizon scan focused on technologies that had the potential for selective recovery, despite the challenges with water quality, and considered a range of Technology Readiness Levels (TRLs). This included an adsorption-based process that has the potential to selectively separate individual REE, and a polymer based selective flocculation technology.

Sep 1, 2024

Many young mining engineers do not consider consulting as a possible job, believing that many years of working on-site is required to achieve practical experience, develop expertise and acquire industry contacts. However, mining consultancies employ engineers with varying levels of experience, including part-time university students, graduates and engineers who are relatively new to the industry. This paper outlines the role of a young engineer in a large mining consultancy and the benefits to both the consultancy and the client of having a mix of consultants with a diverse range of experience. From the authorÆs perspective, the work experience, lifestyle and rewards of mine consulting are compared to site based work, including a discussion on whether consulting is able to offer the professional development that a young engineer needs.

Jan 1, 2009

The current economic climate and demand for iron ore has resulted in mine operators being prepared to accept aggressive slope designs and associated failures provided that they can be quantified (ie volume of failure and clean up costs, etc) and incorporated into the mining costs, at a feasibility study level. This has numerous implications for pit slope design/geomechanics. Typically when geotechnical engineers conduct slope stability modelling a single value, usually the average or mean value for model input parameters (ie structural orientations, material properties and hydrological conditions) are chosen. The implications resulting from using a single value for model input parameters will vary depending on how the modeller has chosen the value, ie should the modeller choose a mean value from a log-normal distribution of material strengths an optimistic representation of the stability may eventuate, consequently if the designer decides to conservatively downgrade the values by a nominal factor, a pessimistic representation of slope angles may occur, which would result in excessive stripping and mine development costs. A more realistic and representative way to model the inherent variability of geological/geotechnical conditions would be to do so probabilistically. Whereby the modeller can assess the variability of the geological structure as observed/recorded during the core logging process and a similar approach for the material strength properties. The final model output would be a distribution of factors of safety in relation to overall slope angles, ie probabilities of failure for individual slope angles could be determined. This output (graph) could be modified by the mining engineer to incorporate mining costs as well as clean up costs for the respective slope angles and associated failure volumes, ie probabilities of failure. The author intends to provide a detailed overview of the processes involved in deriving a geotechnical design, ie; starting from the data collection phase (core logging/face mapping), through to the data interpretation and formulation of slope parameters; determining the variability and uncertainties associated with each of the process; ensuring that it is adequately captured in the model input parameters; and how the mining engineer could utilise this information to derive final feasibility study mining costs.

Jan 1, 2009

By M Hawkes, Z Ji Gang, Z Ming, R Hassell

As underground mines become more geotechnically challenging with increasing depth and excavation size, the requirement for ground support to be installed as per design becomes more critical. The verification of installation quality for cable bolts and grouted rock bolts is difficult to assess. Current methods to control quality have limitations; pull testing is largely inconclusive with only extremely poor installation being identifiable. Audits during installation can only capture a small percentage of installed bolts. Following large rock mass displacement from either squeezing ground or seismic events, even previously well installed bolts may have yielded and require replacement. A method to provide an improved understanding of the reinforcement installation quality is Non- Destructive Testing (NDT) using acoustic reflection. To validate the accuracy of an NDT system, both plain and bulbed strand cable bolts were grouted in clear plastic tubes. The encapsulation grout quality was deliberately varied from full encapsulation through to partial encapsulation and a range of different size voids. The clear tubes allowed the ground encapsulation to be observed. Cable bolts strands were cut at varying lengths and different water cement grout ratios were used. Acoustic testing of the cable bolt specimens was completed blind; the technicians were not aware of what was being tested. The NDT results correlated well with the grout encapsulation, with differences between full encapsulation, minor voids and major voids being determined. The different water cement ratio and bolt lengths (including when partially cut) were also identifiable but with some discrepancies. Trials of the technology underground have also shown the data collection process to be relatively quick with each bolt taking 1-2 minutes to test, with interpretation of the results able to be completed soon after. The NDT results collected from the underground trial showed a wide variance in cable bolt grout encapsulation quality indicating that there were installation issues.

Mar 15, 2021

By D P. Blair

The theme of this conference is blasting productivity. This article only considers the technology aspect of this theme, and in particular, the collection and analysis of experimental data. In many cases, field trials are set up to collect data on variables such as fragmentation and vibration with the aim of comparing different explosive products and/or blast designs. An important aspect of such trials is the collection of sufficient data to draw sound conclusions. In this regard, there is no doubt that the scatter in real data is the root cause of all problems of obtaining misleading results due to an insufficient number of trials. This article shows that the typical one-off trial has a high probability of producing misleading information, which could be considered to be worse than having no information at all. Assuming that sufficient data has been collected, this article also highlights the methods that can be used to make the most of that data. These methods include the application of appropriate statistics that are dependent on the nature of the scatter in the data, and the use of some of the more recent filtering and spectral approaches that can be used to reduce the noise in measured blast signals and increase the resolution of their spectral characteristics.

Nov 8, 2011

By N Arrys, A Jani, S Shahin

Optimising pit slope stability and reducing strip ratio of a mining operation are two key tasks in geotechnical engineering. With a growing demand for minerals and an increasing cost associated with extraction, companies are constantly re-evaluating the viability of mineral deposits and challenging their geological understanding. Within Rio Tinto Iron Ore (RTIO), the Structural Geology (SG) team investigate and collect critical data, such as point based orientations, mapping and geological inferences from adjacent pits to remodel deposits where previous interpretations have failed to account for structurally controlled slope failures. This work outlines the key methods utilised by the Structural Geology team which form the foundations of informed orebody knowledge and subsequent geotechnical design recommendations. This publication utilises the results from a recent analysis to highlight the benefits of this methodology and how it has impacted the economics of an operation through optimisation of a pit wall ‘cutback’ and crest relocation.

Sep 1, 2024

By H Mischo, M Ferber, M Donner, B Jung, S Grehl, A Dietze

Mobile robots have been making impressive inroads in a variety of domains. Within the Mining-RoX project, Technical University Bergakademie Freiberg is exploring a further frontier for mobile and autonomous robots: underground mines. The potential benefits of mobile robots in underground mining are plentiful as underground mines are strenuous and potentially dangerous working environments for humans. A higher degree of automation, with robots either acting as helpers for human miners or even replacing all human personnel deployed underground, could help to significantly reduce mining costs. In disaster cases, rescue robots could help to find missing personnel. Unmanned mines operated by robots alone would not endanger human lives at all. Further use cases, and a particular focus of the Mining-RoX project, are mobile robots that gather sensory information of the underground mine (eg for the purpose of creating detailed 2D and 3D maps) as well as monitoring environmental conditions such as air and water quality. This paper presents the design of a prototypical mobile robot for mapping and monitoring underground mines. A generic robotic platform was extended with various 2D and 3D imaging devices as well as other sensors. First results from test runs in an underground mine are reported. Maps of two sections of the mine enhanced with localised sensor measurements were successfully created.CITATION:Grehl, S, Donner, M, Ferber, M, Dietze, A, Mischo, H and Jung, B, 2015. Mining-RoX – mobile robots in underground mining, in Proceedings Third International Future Mining Conference, pp 57–64 (The Australasian Institute of Mining and Metallurgy: Melbourne).

Nov 4, 2015

By R Zhang, J Xu, X Lv, C Bai, S Zhang

This paper studies the grinding behaviour of vanadium-titanium magnetite concentrate in a ball mill. The grinding kinetics, surface morphology, lattice distortion, wettability and moisture capacity were analysed. Grinding kinetics equation was established based on population balances model with the size distribution data from a laser diffraction technique. The SEM photos of the ground concentrate showed that the surface gets rough with increasing grind time. Agglomeration of fine particles was enhanced when the grinding time reached 30 minutes. X-ray diffraction results showed that a loss in crystalline occurred with increasing the grinding time. The peaks of the X-ray diffraction patterns are significantly broadened with increasing grinding time. Wettability, characterised by contact angle between the material and water, improved due to the fact that the surface roughness increased with increasing grinding time. Moisture capacity of concentrate ascends abruptly in the first three minutes and then changed slowly with increasing grinding time. The water transfer coefficient in the particles increased rapidly in the first six minutes and then decreased quickly until grinding time reached 12 minutes.CITATION:Zhang, R, Lv, X, Bai, C, Xu, J and Zhang, S, 2013. Wet grinding of ?vanadium-titanium magnetite concentrate in a ball mill, in Proceedings Iron Ore 2013 , pp 511-518 (The Australasian Institute of Mining and Metallurgy: Melbourne).

Aug 12, 2013

The general types of industrial behaviour of liberated valuable sulfide minerals in the 0 - 10 ¦m size fraction are described and tests to explore on site at a concentrator the general nature of any deficient behaviour are discussed. In addition, the general types of behaviour of the gangue minerals in this size fraction are also described in terms of their mechanisms for recovery. These behaviours are also discussed in terms of the type of grinding device and grinding environment in which they were produced and the target grinding product size. Major recent improvements in the industrial capabilities of grinding devices are discussed.Present difficulties in characterisation of particles in the 0 - 10 ¦m range are described and desirable improvements for the future are outlined. Further, desirable improvements for industrial processing of valuable minerals in this size range are discussed along with some remedial actions.

Jan 1, 2005

By T E. Norgate

Salinity in Australia is caused by over irrigation and land clearing for agricultural use over the last 100 years. It is now the biggest threat to the quality of land and water in the Murray Darling Basin and Western Australia. Pumping the saline waters straight into the ocean or transporting the solid residue (mainly sodium chloride) to the ocean after evaporation of the water is expected to cost the taxpayer millions of dollars every year. This paper proposes that the salinity problem of Australia, at least in part, can be converted to an asset rather than a liability if it is exploited and used to make value-added products. The more value made out of saline waters, the more saline water is processed and therefore the more salt is extracted from the land. The value-added products that can be made out of saline waters are numerous and diverse. Rough calculations show that value addition to the saline waters could potentially generate up to $A 200 million per annum business in the Murray-Darling Basin. Although it is a challenge to make cost competitive products and find markets for these products it is possible that up to $A 100 million per year may be gained from import substitution. Value addition to salinity would also reduce the threat on the environment and existing agricultural industry. Investment to add value to salinity will create business in the region, nurture the local small population communities, and increase services and long-term employment.

Jan 1, 2002

By Y Li, D J. Williams, E Topal

A mine waste rock dump does not have any intrinsic value, yet is an inevitable structure in surface mining operations. Since the purpose of mining is to maximise profit, possible expenditure reduction in hauling waste rock to the dump, which can represent up to 50 per cent of the total operating cost, is highly desirable. Apart from cost, potential acid mine drainage (AMD), due to seepage from surface waste rock dumps containing reactive waste rock, could threaten the ecological balance, drinking water supplies and irrigation systems downstream from a mine site. In order to minimise these potential risks, selective placement of benign and reactive waste rock, and the encapsulation of reactive waste rock by benign waste rock, need to be carried out during the construction of the rock dump.In this paper, a new methodology, based on mixed integer programming (MIP) is developed to manage waste rock dumping. The model aims to minimise waste rock haulage costs by locating the optimum destination(s) for each waste rock block, while at the same time controlling the placement of reactive waste rock to minimise the potential for AMD. Tests on small-scale virtual data demonstrated that the model is capable of dealing with selective placement of different waste rock types, encapsulating reactive, potentially acid forming (PAF) waste rock, and stockpiling benign waste rock for encapsulation and rehabilitation purposes. The solution time for the MIP model is far less than the traditional manual approach, and the resulting schedule is up to 46 per cent more cost effective.CITATION:Li, Y, Topal, E and Williams, D J, 2012. Mathematical approach for better mine waste rock dumping management, in Proceedings Life-of-Mine 2012 , pp 207-214 (The Australasian Institute of Mining and Metallurgy: Melbourne).

Jul 10, 2012

By S A. Ravishankar

An overview of flotation reagents used in sulfide and non-sulfide separations, from an industrial perspective, is given in this presentation to highlight the current applications knowledge. The historical and theoretical aspects, which are well documented in numerous books and reviews, will only be highlighted, when necessary, to support the theme of this paper, viz critical analysis of reagent research, design, selection and optimisation with an emphasis on relevance to plant needs and practice. The three types of flotation reagents; viz collectors, frothers and modifiers, used currently in the industry are briefly reviewed; pitfalls and gaps, arising from somewhat arbitrary and reductionistic practice in reagent applications, are identified; and the impact of environmental regulations on current and future reagent development is discussed. The importance of frothers and modifiers, which have received less overall attention than collectors, is highlighted. The need for a rational, holistic (or ætotal systemÆ, ætop-downÆ) approach for reagent design, selection and optimisation is discussed with a view to provide remedies for pitfalls and a platform for filling gaps in reagent chemistry and applications, and to develop reagent technology that can deliver robust solutions to plant needs. Flotation Matrix 100TM, a comprehensive package designed at Cytec to incorporate all the elements of the holistic approach û viz definition of mineralogy and plant needs, rule-based expert system rational reagent selection, and laboratory and plant best practices û will also be described.No paper available for this abstract

Jan 1, 2005

By M Akop, G Phillips, L Elliott

An estimation geologist has many tools in their kit and using the correct one for the job is vital for creating a useful model. Reconciliation is a key step to monitor the performance of a resource model and to ensure the correct tools have been selected and appropriate parameters are set. This paper presents an example of refining the estimation methodology for a Channel Iron Deposit (CID), resulting in an improved model. Rio Tinto Iron Ore (RTIO) CIDs are unique iron ore deposits located in the Pilbara region of Western Australia and contribute a significant volume to the world’s seaborne iron ore market. A problematic feature of these deposits is the irregular dispersion of clay pods that cannot be delineated with confidence within the resolution of the exploration drilling. Resource to grade control reconciliation showed an over-prediction of high-grade material in the resource model. A fresh approach was required to improve grade and tonnage predictions. Historically, clay pods were delineated using traditional wireframing techniques and estimated using ordinary kriging with hard boundaries. The new method utilised indicator kriging to estimate the probability of clay. Probabilities generated from the indicator kriging estimate were used as an additional weighting following the ordinary kriging of grades. Results showed indicator kriging improved global high-grade tonnes reconciliation, however, as expected, it did not improve the spatial prediction of clay. Based on improved reconciliation results indicator kriging has now been adopted as a suitable alternative for analogous CIDs at RTIO. These improvements benefit the mine planning process, but do not replace grade control models.

Mar 22, 2022

By K Brand, M J. Ind, M Rynhoud

Water management at a tailings storage facility (TSF) presents one of the major risks to the safe performance of the facility. International and domestic dam safety guidelines assess a dam’s hazard category based on the consequences of a dam failure and the subsequent downstream damage to the environment and communities.Often a rigorous risk assessment is undertaken during the design stages to identify and control hazards associated with water management through life-of-mine (LOM) phases. However, as experienced during the recent downturn in commodity prices, early closure of a mine can occur rapidly and unexpectedly. Although guidelines such as the Australian National Committee on Large Dams Incorporated (ANCOLD) recommend that one of the key objectives of integrated TSF planning is to ‘plan all phases of a tailing dam’s life to ensure adequate storage capacity including early closure ’ (Australian National Committee on Large Dams Incorporated (ANCOLD), 2012) this is often overlooked by owners who are focused on fulfilling the mine’s potential and early closure is not on their radar.CITATION:Ind, M J, Rynhoud, M and Brand, K, 2016. Life-of-mine spillway strategy – managing risk associated with surface water at a tailings storage facility, in Proceedings Life-of-Mine 2016 Conference, pp 209–211 (The Australasian Institute of Mining and Metallurgy: Melbourne).

Jun 28, 2016

The Cadia Valley Operations currently hosts a large operational open pit, a large operational sublevel caving underground mine and two other underground projects at the study stage. This scenario creates an unusual situation for the evaluation and planning of a fifth major open pit project. The Cadia East Open Pit is a large gold-copper development located adjacent to the operational open pit and above one of the underground projects. A study team is conducting a comprehensive and robust analysis of the target orebody. Two key factors for this project include the existing and planned projects within the valley and the wide range of available mining methods. The aim for the study team is to present an optimal and practical case which suits the entire Cadia Valley Operation. A rigorous and robust analysis of the situation requires that each factor be properly evaluated. A modular system has been developed which allows the wide range of scenarios to be quickly and meaningfully considered. Sensitivities for each module drive the further development of that particular module. As each scenario progresses, an assessment is made evaluating its value, strategic value and practicality. In such a way, the number of scenarios is gradually reduced at each stage to produce a final short list of feasible cases. Each scenario on the shortlist is then assessed with regard to the existing operations and other projects. A qualitative and quantitative analysis is made. This ranking is used to provide the recommended case.

Jan 1, 2007

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's user-friendly interfaces. Presentation of the results is enhanced by Excel'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