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By B Stewart

It has long been recognised that knowledge of the conditions existing in a mine after an incident is essential in deciding whether to deploy responders as part of the incident recovery process. Applying this knowledge in a structured manner to the assessment and the acceptability of the risks likely to be faced by those teams during response activities before authorising their deployment is an onerous task incumbent upon the person controlling the incident response. The Mine Event Management System (MEMS) provides structure and coordination in the management of mine events. It assists with the skills and knowledge for incident control teams to effectively manage any emergency or non-emergency event, be it large or small. In cases where multiple organisations are involved, the MEMS promotes effective joint operations through the use of common terminology and structure to provide seamless communication between agencies at all operational levels. The SQL-based software developed by Queensland Mines Rescue Service (QMRS) assists decision-makers to make considered options; it does not make decisions for you. When set-up, it allows the information that already exists within a mine’s Safety Health Management System that is relevant to the incident to be accessed and considered rapidly within the pressured environment of an emergency. Additionally, the incident specific questions contained within MEMS focuses the management team on gathering and assessing information relevant to the incident as it progresses. The software’s event log can be utilised as an auditable document for post incident investigation. The MEMS provides a process to properly consider the adequacy of the information available upon which decisions have to be made, to consider and acknowledge the hazards of the environments within or adjacent to which responders will need to work and to acknowledge and authorise the entry of responders into or to remain within a mine either during or post an incident occurring, once an acceptable level of risk is achieved.

Apr 16, 2024

By P Church

What is the best method of splitting a sample from a reverse circulation drill rig? How important is it to obtain a correctly split sample? What is the impact of an incorrectly split sample? These are just a few of many questions asked daily in the mining industry with regard to sampling. Modern sampling theory is well described in the literature in texts and is taught in short courses throughout the world, however little has been published on the relative performance of sample splitting devices used in the field. This paper compares the performance of the Jones tiered riffle splitter with a cone splitter manufactured by SGS Metal Craft in Western Australia. The testwork was carried out at AnglogoldÆs Sunrise Dam Gold Mine, 55 km south of Laverton in Western Australia. Mineralisation at Sunrise Dam is hosted in a structurally complex framework of shear zones with dips that range from steep (70¦) to shallow (25¦). The deposit is characterised by significant amounts of coarse gold, which presents a challenge in sampling, analysis and grade estimation. The three major areas where sampling errors can occur are in drilling, sampling, sample preparation and analysis. Sampling errors attributable to drilling and sample preparation often far outweigh the errors made at other stages in the process, however historically most effort to identify sampling errors has concentrated on the laboratory and analytical procedures. Splitter design and cleanliness can have a large impact on sample collection and preparation. Splitter performance was tested with respect to sample weights, particle size distribution, and gold grade consistency. The aim was to determine if each particle has an equal probability of being sampled, the resulting sample has integrity, and if any segregation problems occurred. The cone splitter was found to provide the best split in terms of particle size distribution, with no apparent size bias. Duplicate samples had more comparable masses than those provided by the riffle splitter. Most importantly, the cone splitter gave less grade variability between duplicate samples than the riffle splitter. Testwork also confirmed that, like the riffle splitter, the cone splitter must be oriented vertically and the design of the rig or cone splitter trailer should accommodate this requirement.

Jan 1, 2003

By C Beal, S Singh

Sensor-based bulk ore sorting is a form of preconcentration that autonomously measures and physically separates discrete bulk ‘pods’ of run of mine (‘ROM’) or primary crushed material. This case study examines the results of a full scale bulk ore sorting trial undertaken at Cozamin mine in Zacatecas, Mexico in 2019. The bulk ore sorting plant comprised primarily of a mobile jaw crusher, fixed conveyor, MR analyser, and diverter gate. Results of the trial demonstrate that bulk ore sorting could deliver a net improvement in copper metal fed to the processing plant of 6-8 per cent within an equal gross tonnage of ore. Copper metal increases were the result of improvements in mining recovery, where valuable mineralisation is recovered from marginal or sub-grade material that would otherwise be discarded as waste or stockpiled as low-grade. The increase in mining recovery more than compensates for metal losses suffered in the bulk ore sorting plant.

Nov 10, 2020

Much of the coal and gold mining industry of New Zealand is small scale. Funding is tight and mechanisation limited. The country has many well documented small coalfields (some with significant outcropping) and alluvial gold deposits. These are generally remote, difficult to access (physically and otherwise) and of submarginal value (largely a consequence of size when viewed for extraction by traditional techniques). The industry is also burdened by environmental and bureaucratic constraints. The above over simplified setting suggests to the Author, a newcomer to New Zealand, the opportunity to consider some novel concepts based on technology and techniques developed overseas or borrowed from other industry sectors. The objective being to make viable in economic and environmental terms projects that might otherwise be stillborn if considered for exploitation by conventional means. The paper mainly discusses 2 concepts focusing on the application of augers for exposed high wall or outcrop coal and micro-tunnelling augers for alluvial gold extraction. These may be considered high mobility 'container' (as in shipping container) packaged, or 'non invasive' mining systems. It is stressed that these are but concepts and have yet to be subjected to rigorous financial or engineering scrutiny. This could only follow their acceptance by, and input from, New Zealand miners. There will also be brief mention of a new modular conveyor system which might have application within the concepts or existing small scale mineral extraction operations and mention of a project currently in progress to apply tangible 'sustainability' to underground coal mining.

Jan 1, 1996

To enable ammonium nitrate-fuel oil (AN-FO) to be used on an equal weight basis with nitroglycerine explosives, smaller diameter bore holes became necessary with consequent modifications to drill steel and burden on holes. Detonation of AN-FO in small diameter holes proved successful both with and without primer charges but some alterations were required to adapt anoloders to the smaller holes.Important factors in training all operators in the new charging method were the retention of improved fragmentation, avoidance of excessive overbreak and keeping wall rock dilution to an absolute minimum. The successful storage of ammonium nitrate in climatic conditions with daily temperature fluctuations above and below the critical 90°F has been achieved.INTRODUCTIONTechnical aspects of ammonium nitrate-fuel oil (AN-Fa) blasting agent are well covered in recent literature. This paper deals primarily with the manner of its introduction as the principal explosive underground at Great Boulder Gold Mines Ltd. and with the many problems encountered in the process. Following reasonably successful experimental firings in June 1962', using granular ammonium nitrate and an anoloder, permission was granted by theWestern Australian Mines Department to carry out test work in selected areas of the mine. The permit allowed for fuse firing only, and for a mixture of AN-Fa containing between 5t and 6 per cent fuel oil, with an adequate primer.The use of AN-Fa on an equal weight basis with nitroglycerine explosives, involved smaller diameter holes with alteration to ground burden and modification to drill steel.Initial tests indicated that it was apparent that AN-Fa could not replace gelignite on an equal weight basis if the...

Jan 1, 1965

By R Grogan

Nautilus Minerals Inc is a sea floor resource exploration and development company focused on developing the Solwara 1 Project, a copper-gold sea floor massive sulfide deposit in the territorial waters of Papua New Guinea, for which it holds a mining lease and associated environment permit.Economies depend upon four key types of capital: built, natural, financial and human. Natural capital consists of the ‘minerals, energy, plants, animals, ecosystems (climatic processes, nutrient cycles and other natural structures and systems) found on Earth that provide a flow of natural goods and services’ (Daly and Farley, 2004). Many ecosystem goods such as fish, fruit and water are already valued and sold in markets; however, some ecosystem services are not amenable to markets and have remained unvalued in traditional accounting methods, even though they provide significant value (such as flood protection, climate stability etc; Batker and Schmidt, 2015).There are now economic methods available to quantify and value natural capital and many non-market ecosystem services. When valued in dollars, these services can be incorporated into a number of economic tools, including benefit-cost analysis, accounting, environmental impact statements, asset management plans and rate of return on investment calculations. Their inclusion ultimately strengthens decision-making. When natural capital assets and ecosystem services are not considered in economic analysis, they are effectively valued at zero. This omission can lead to poor decisions, inefficient capital investments, higher incurred costs and losses due to unexpected events (Batker and Schmidt, 2015).In 2015 Earth Economics was commissioned by Nautilus Minerals Inc to conduct an independent, objective environmental and social benchmarking analysis of the proposed deep seabed Solwara 1 mine with terrestrial copper mines (referred to as ‘the report’). The report represents the first ever natural capital accounting and ecosystem goods and services framework for seabed mining.The report compares the proposed Solwara 1 mine with three terrestrial mines: Bingham Canyon (Utah, USA), Prominent Hill (South Australia, Australia), and Intag (a proposed mine in Intag Province, Ecuador), and provides a natural capital accounting assessment for all four operations.CITATION:Grogan, R, 2016. Natural capital accounting – a sea floor mining application, in Proceedings Life-of-Mine 2016 Conference, pp 2–4 (The Australasian Institute of Mining and Metallurgy: Melbourne).

Jun 28, 2016

By J E. Everett, K Jupp, T J. Howard

Precrusher stockpiles are designed principally as buffers to decouple the mining and processing operations. They are usually paddock dumped or dumped over a face to form fingers by dumping haul truckloads and reclaimed by front-end loader in an ad hoc manner. In addition, they are often not built and reclaimed to completion but continually added to and extracted from. While this design suits the mining process and is operationally simple, there can be little confidence in the grade of the ore that is fed to the crusher. This makes short-term grade control difficult and reconciliation back to the mine face imprecise. Well-designed and operated precrusher stockpiles can overcome these deficiencies.The different types of grade variability in mining are reviewed in this paper. The role of precrusher stockpiles in reducing short-term variability is discussed and their ineffectiveness in addressing long-term variability is highlighted. Their role in removing the serial correlation of the extracted ore is explained.Precrusher stockpiles carry out the four, at times competing, objectives of storing, buffering, blending and grade separation. Their actual design and operation result from a compromise between these four competing roles. These roles are explained in detail along with the advantages and disadvantages of the different types of precrusher stockpiles. The recommended blended-in blended-out stockpile (BIBO) design is discussed in detail. Matched pairs of BIBO stockpiles of limited tonnage built and reclaimed to completion retain the best knowledge of grade and facilitate the reconciliation process.Simulation studies have been carried out on BIBO stockpiles to understand the blending opportunities of the different options for building and reclaiming, and to identify the methods that achieve maximum blending. It was found that laying down rows in one direction and reclaiming across these rows gives the best blending. Matching the width of the reclaim face with the daily crushing requirements is also important. The length of the rows, and building in either one or two layers has little effect on the extent of blending.Appropriate design can provide a reasonable compromise between the four objectives.CITATION:Jupp, K, Howard, T J and Everett, J E, 2013. The role of precrusher stockpiling for grade control in mining, in Proceedings Iron Ore 2013 , pp 203-214 (The Australasian Institute of Mining and Metallurgy: Melbourne).

Aug 12, 2013

By M Salu, G J. Kay

"As underground mines increasingly face the challenge of maximising production without losingfocus on safety excellence, the ability to predict the eff ectiveness of mine seals and stoppings andthe identifi cation of defects plays an increasingly important role in mine ventilation management.While technologies for sample testing installed seals provides signifi cant assurance, the difficulty of conducting tests in operational environments, combined with the production impact of destructive testing procedures, has led to the development of a new method for non-destructively testing ventilation control devices (VCDs). This paper addresses the challenges of in situ testing and reviews the approaches previously employed to verify the quality of VCD installations. It then describes a new testing methodology jointly developed by Whitfield Minerals PTY Ltd and Parsons Brinckerhoff (PB) and the range of tests that have been carried out in the laboratory, above ground, at trial underground sites and in active coal mine operations. Although this is a new approach to testing underground VCDs, the method employs recognised testing equipment in a new application. The aim of the new non-destructive technology is to not only verify the thicknessand therefore overpressure rating compliance, of new VCDs, but to allow mine operations t oidentify and locate defects in installed VCDs without causing damage to the material structure.Currently it is difficult, time-consuming and costly to carry out physical sampling and testing ofevery VCD. Therefore, a reliable and accurate means of non-destructively testing concrete andplaster seals in situ will provide substantial operational and safety benefi ts to the underground coal mining industry."

Jun 1, 2012

By A Whaanga

The use of photogrammetry has greatly increased the accuracy of 3D mapping underground. However, this has not reduced the need or desire for geologists to produce plans and sections showing an interpretation of the mapped geology. At the Waihi Underground Gold Mine, a hybrid solution has been developed that utilises the accuracy of photogrammetry and mapping onto face photos with the CAD-based Deswik.MappingTM functions to create plan and section maps. These have the benefit of looking like traditional paper maps but are more spatially accurate and richly attributed with metadata that can be filtered and exported to downstream processes. Deswik.MappingTM is a tablet-based solution that allows the geologist to map digitally with a stylus. Automation is utilised for the updating of survey as-builts, approved designs, drill holes, geological mapping, vein interpretations and mine work areas, reducing the requirement to print out maps at various locations and scales. Having 3D mine software on a tablet device provides a wealth of features not available when using paper: scaling is a problem of the past; information can be turned on and off; features can be viewed in 3D; and measurements between points of interest can be calculated in 3D space, for example, between vein wireframes and drill hole sample information. A suite of custom scripts has been developed that take the spatially accurate, registered and attributed polyline data from photogrammetry scans and converts them to a geological mapping legend with vein textures, structural information, and lithological boundaries. These 3D maps can be plotted in plan or section view and satisfy the requirements of the most ardent paper map supporter.

Mar 22, 2022

Copper ores are widespread through the Lachlan Geosyncline in New South Wales, but the size of the orebodies is generally small. The largest deposits occur in the Cobar district where an iron-rich copper ore type has been developed in Silurian sediments. Similar de- . posits to the south in the Nymagee-Mt. Hope-Melrose districts are related to quartz feldspar porphyries of probable Upper Silurian age. Deposits to the east in the Tottenham-Girilambone districts are less complex mineralogically and are possibly related to an ultra-basic source.Copper mineralization in the Highlands further to the east is often developed in Ordovician andesite or MiddleUpper Silurian acid volcanic sequences. The deposits in andesite contain considerably less galena than those in the acid extrusives; a small proportion of the mineralization in the latter has texture, mineralogy, and geologic setting analogous to the Captain's Flat copper-Iead-zinc deposit, for which both syngenetic and epigenetic origins have been proposed. Very little copper mineralization occurs within granitic material, even though rocks of this type ranging from Silurian to Carboniferous in age crop out through much of the geosyncline, and the extent of the metal contribution from plutons to the deposits in volcanics is open to question. Numerous deposits are known in the contact zone around Mid-Devonian and Mid-Carboniferous granites, however, and the formation of these orebodies has undoubtedly been influenced by plutonic activity. Small occurrences of copper with associated minor nickel sulphides are developed in a narrow serpentinite belt of possible Lower-Middle Devonian age in the southern section of the Highlands.

Jan 1, 1970

By Mosusu N

Geothermal anomalies of different types occur within distinct geological/structural settings in Papua New Guinea. According to R.F. Herring, geothermal occurrences in Papua New Guinea can be classified into two types, those related to vulcanism (Lihir, Rabaul and other series of islands along the volcanic arc) and those resulting from a regional heat flow probably caused by radiogenic sources, for instance those in the Wau/Bulolo area. The manifestation of this potential source of energy generally coincides with either converging or diverging tectonic plate boundaries. Previous inventories on thermal waters were carried out by vulcanologists from the Rabaul Observatory in the early 1960s. However, these studies rarely included chemical analyses of water and gas emissions and the investigations were carried out in an ad hoc manner, generally as a secondary activity. The most recent investigation on thermal waters was conducted on Lihir Island in connection with the development of the open pit gold mine. These studies included detailed exploratory drilling to a maximum depth of 730 m, and a water chemistry isotopic sampling and analysis programme. The hydrothermal waters were not considered as an energy source but as a hazard during the development stage of the mine. Nevertheless, the geothermal anomaly observed at Lihir includes hot springs emerging along the coastal zones with temperatures that approach 100¦C, steam, and thermal borehole waters with temperatures that exceed 200¦C. Chemical analysis results of thermal fluids from Rabaul, Talasea and other areas in Papua New Guinea generally show high total dissolved solids and low pH. In contrast, recent results from the deepest and hottest thermal source at Lihir shows a neutral pH, a Na-CI-SO4 composition and temperatures above 200¦C. Despite the concentration of chloride being similar to that of sea water, other chemical results and stable hydrogen and oxygen isotopic compositions of thermal fluids imply the source to be mixture of local meteoric water and deep thermal water rather than sea water. Results of geothermal modelling suggests that the total geothermal uptlow is equivalent to 54 MW.

Jan 1, 1997

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 Umar N

Traditional exploration has been undertaken by both local and overseas experts to discover tin deposits in Indonesia over almost 300 years. Indonesia is part of a tin belt which runs from Myanmar in the north through Malaysia to Singkep, Bangka, and Belitung islands in Indonesia in the south. The discovery of alluvial tin deposits is becoming harder as the more obvious geological targets are exhausted and topographical conditions become more difficult. New approaches are required to sustain successful exploration. There are indications that tin deposits can be found at depth on-shore as well as off-shore. These deposits are found associated with tough clays. On-shore tin exploration is hampered by swampy areas, while the off-shore search is often affected by difficult sea conditions. These factors lead to increases in the cost of exploration as well as the cost of subsequent production. Tin price fluctuations and environmental issues are also of major concern in the planning of the future operation of tin mining in Indonesia.

Jan 1, 1996

By A R. Penney

Safety management, both personal and that associated with catastrophic hazard, helps to define the success of mining companies. Personal safety management, often categorised by slips, trips and falls, has been widely addressed, with numerous approaches successfully adopted. Catastrophic hazard can lead to a single accident (eg ground collapse, underground fires etc) causing multiple fatalities. Catastrophic hazard management in mining is an emerging discipline, and as such there are various pitfalls to demonstrate its effectiveness and success; it is much more than simply meeting regulatory requirements. Various standards, guidelines, and leading practices are available for reporting key performance indicators. While measuring and reporting safety related key performance indicators (KPIs) such as Total Recordable Injury Frequency Rate (TRIFR), Lost Time Injury Frequency Rate (LTIFR), are important, they often lack detail, and give little insight into the effectiveness of catastrophic hazard management strategies and controls. Catastrophic hazards are low likelihood, high consequence events, and as such demand a different management approach. Companies cannot use the suite of personal safety metrics to help demonstrate management of catastrophic hazards. In-field verifications have revealed that senior management commitment to safety is often clear, well organised, and resourced. However, there are often some inconsistencies between what management promotes and plan, to what the operational teams understand and implement. Communication and clear understanding of expectations were the common themes identified to help empower supervisors to reinforce requirements of catastrophic hazard management. A lack of specific, measurable, and time-sensitive goals and objectives for the short- or medium-term, making it challenging to track progress was another key observation. Development of an integrated, multi-disciplinary auditing process executed by an experienced team of technical subject matter experts, provided an in-depth understanding of the requirements of catastrophic hazard management. Areas such as underground fire prevention, explosive storage, electrical safety, mobile vehicle interactions, ground control, inrush, and shafts and winders management have substantial overlap and intertwined processes, and similar strategies for emergency responses. Auditing of catastrophic hazards and safety management systems compliance is only the first step in safety assurance. Completing operational performance audits in technical areas and benchmarking the site verification of safety management documents and verifications forms a critical part to clearly demonstrate industry leading safety practices. No longer is it the external inspection or regular hazard management plan review requirements that dominate, but rather the culture of continual hazard identification, management, controls verification, underpinned by improvement and follow-up verifications of the corrective actions.

Mar 29, 2023

By Walton S, Wheeler D. J, Sargent D. M, Ting L. Y

Goonyella-Riverside mine is an open cut coal mine in Central Queensland. One component of the mining operations at this site is an uncompacted spoil dump some 50 m above the natural ground surface and over 300 ha in extent formed as a result of bucket wheel excavator operations. Plateau area slopes are 0.5¦ to 1.5¦ with irregular outer dump slopes of 9.5¦ - 17¦Investigation was undertaken and a series of trials planned to assess the suitability of a variety of stabilisation proposals to meet the client's requirements and to conform with Department of Resource Industrystabilisation guidelines.

Jan 1, 1992

By J Jardine

An improved ground support method for development intersections, wide spans and stope brows was implemented at Kanmantoo mine. The method uses a jumbo to simultaneously drill and install self-drilling anchors (SDAs) to depths from 4.5 m to 7.0 m. Resin is subsequently pumped into each SDA using a specially designed integrated tool carrier basket, with plating occurring within 10 mins due to rapid resin cure. This methodology means that SDAs can be installed rapidly due to reduced process steps and wait times with reduced hazards to personnel. Cablebolts are used extensively in underground mines to reinforce the ground in wide spans, such as at intersections and stope brows. The flexible cablebolt tendon allows for a long, continuous and high-capacity reinforcing element to be inserted into the rock. A common cablebolt installation practice at Australian underground mines that do not utilise a mechanised cable bolter, is for cablebolt holes to be drilled by a jumbo or longhole rig, hand installation and grouting by a service crew, then plate tensioning following a grout curing wait time of typically 12 to 24 hours. This process involves multiple separate labour-intensive work processes and results in reduced availability of priority headings. This paper discusses the development history of vertical SDA use in wide spans at Kanmantoo mine. The installation process is fully described, including aspects such as reliable in-hole coupling of SDAs, resin selection and pumping aspects. A cost benefit assessment, and a case for ground stability are presented to compare cablebolt use to SDAs in development intersections.

Mar 29, 2023

By Wylie A. W, Mathew PJ

Bulk density and grade were determined on a variety of ore samples from the Mount Tom Price iron ore mine and the interrelationship between these properties and porosity deduced.Variable porosity is responsible for the wide scatter of data points and low accuracy of prediction in the grade of a single sample from grade/bulk density relationships.However, with a sufficient number of such data points, as from a nuclear geophysical borehole logging operation, the mean ore grade in an exploration-type drill hole (~63 per cent Fe) could be determined by regressionanal~sis with 95 per cent confidence intervals of approximately ± 1 per cent Fe. From the same logging operation, utilizing core data for calibration of the probe, the -mean fractional porosity for the drill hole (0·19 ± 0·016 at 95 per cent confidence interval) was deduced. This is less accurate than the corresponding result obtained on core material in the laboratory (0·20 ± 0·005).The range of porosity was from 0·08 for dense, high grade sectIOns of the ore, to 0·28 for friable ore of high grade or goethitic ore of lower grade. Shale band porosity ranged from 0·15 to anomalously high values of 0·48 believed to be caused by leaching of iron minerals from the shale. Porosity values for the iron ore component of the deposit are comparable to those found for the Cockatoo Island (W.A.) mine, and for sections of the Krivoy Rog (Ukraine) iron ore deposit of the Soviet Union.

Jan 1, 1978

The Australian Coal Combustion Testing and Research Facility has been operating commercially for one year and during that period coal product evaluations have been conducted on behalf of four coal companies and one electricity commission. The facility is equipped to assess the behaviour of steaming coal in milling, combustion (including flame stability, burnout and heat transfer), ash deposition and erosion, fly ash collection and gaseous emissions. The relevance of the results of the pilot testing to industrial practice was demonstrated during the calibration of the facility using four coals burnt in Australian power stations. The calibration coals were from the Tarong and Gladstone Power Stations in Queensland, tluja Power Station in Western Australia and Bayswater Power Station in New South Wales. Also an opportunity arose to visit an overseas power station to observe a full scale test burn using one of the early coals tested on a commercial basis in the combustion test facility. The calibration trials showed excellent agreement with industrial coal performance in t:orms of flame stability, turndown, carbon burnout and gaseous emissions. Encouraging correlations were also found in the case of furnace radiation, boiler deposits (slagging and fouling) and electrostatic precipitation. In the case of the last group the only real reservations about the correlations are due to the non-availability or qualitative nature of results collected around the power stations. In all cases there is a high degree of confidence in the facility's ability to predict the relative performance of different coals and in some cases direct numerical predictions can be Made.

Jan 1, 1987

By C A. Myburgh, S Craig, K Deb

In focusing on open pit mine scheduling, one of the biggest areas that a mining engineer can add value is in the area of cut-off grade optimisation. It is not atypical to add up to an extra 20 per cent in value by bringing forward higher-grade ore and deferring costs into the future.There are many techniques available to maximise net present value (NPV) when applied to open pit mine scheduling. That in itself raises the question of why so many of these techniques exist. The short answer is that none of these techniques are robust. Every time the problem changes, the algorithms also have to change.Instead of trying to make a problem fit the constraints of an existing technique, there is much to be said for usefully hybridising different approaches. This paper describes an innovative approach where evolutionary algorithms are combined with both local search and linear programming. The goal is maximising NPV through optimisation of cut-off grade policy and extraction sequence for an open pit mine. The cut-off/cut-over grade policy produced caters for multiple processing streams and stockpiles.Finally we demonstrate the quality of the algorithm by comparing some results with a well-known mathematical solution.CITATION:Myburgh, C A, Deb, K and Craig, S, 2014. Applying modern heuristics to maximising net present value through cut-off grade optimisation, in Proceedings Orebody Modelling and Strategic Mine Planning Symposium 2014, pp 155–164 (The Australasian Institute of Mining and Metallurgy: Melbourne).

Nov 24, 2014

By J, T C. McCuaig, J Hodgkison, T Fouet

Olympic Dam is the eighth largest Cu deposit and the largest U deposit in the world, with approximately 35 million tonnes of contained Cu and 1.2 million tonnes of U. The most recent resource estimate was for 2.95 billion tonnes of mineralised material with average grades of 1.2 per cent Cu, 0.4 kg/t U, 0.5 g/t Au, 2.6 g/t Ag as contained mineral resources. Olympic Dam is expected to produce >200 000 tonnes of Cu and 4200 tonnes of U3O8 from 9.8 million tonnes of ore in 2004, making it the 12th largest Cu producer in the world. One of the impediments to achieving targeted rates of production has been oversize material (>0.9 m) reporting to stope draw points. A major contributor to oversize material may be overbreak along pre-existing structural weaknesses from stope walls and backs during the production life of a stope. Underbreaking to structures can also have a detrimental effect on the performance of a stope. In an effort to understand the influence of structural geology on stope performance, WMC Resources and SRK Consulting partnered during 2003 to refine the current system of structural mapping, and to use historical data to produce a structural interpretation covering a large part of the mining area. The interpretation has been wireframed in DATAMINETM into a three-dimensional structural framework model. To date, there are more than 600 structures of >50 m strike length incorporated into the structural framework model, which covers a study area 1500 m + 600 m + 350 m. A back-analysis exercise to assess the influence of interpreted structures on overbreak and underbreak was completed for laser-surveyed stopes.

Jan 1, 2004