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By R Wolff

One critical factor in open pit mining projects is the estimation of the recoverable reserves. The reason for this is that at the valuation stage there is a lack of information about future metal prices and production costs. Consequently, the estimation of the recoverable reserves needs to be done based on a fixed break-even cut-off grade (BECG), in which fixed expected metal prices and production costs are assumed throughout the operating life of the mine (OLM). In this paper, an alternative technique for estimating the recoverable reserves of an open pit mining project is presented and explained in detail. The main characteristic of this technique is that it estimates the recoverable reserves of the project using mining costs as reference: this is done due to the fact that mining costs are easier to model than metal prices. Another important characteristic of this technique is that it uses the uncertainty of the geology of the orebody, given by simulations of the deposit, to make final strategic decisions, such as the selection of the operating life of the mine and the optimal production rate, which minimise the risk of not achieving future production targets while maximising the upside potential of future rewards. As it will be shown, the final outcome of the proposed technique is the generation of a robust open pit design, that include cutbacks and ultimate pit limits, called the marginal open pit mine design (MOPMD). One characteristic of the MOPMD is that, at each production period, it will be characterised by their respective geological uncertainty, given as probability distributions of ore, waste and metal quantities, and by marginal economical project indicators, such as cut-off grades and metal prices, among others. The details follow in the paper.

Jan 1, 2006

By S Bailey

In-field sampling programs generally take time, equating to money, and unless you have an onsite laboratory, you have the issue of having to wait long periods for your data. Until recently, field portable X-ray fl uorescence (FPXRF) analysers, which can help provide instant indicative results, were not able to detect penalty elements, such as Al and Si, or do so reliably enough to act upon.The purpose then of this field test then was to show that the latest FPXRF devices are capable of producing reliable readings on field samples of variable grain size, in particular for Al and Si, such that the readings still correlate well with the assay for those samples and thus be reliable for an iron ore grade control application.We tested RC chip samples on-site in the Pilbara, Western Australia, with the Niton, analysing for a range of elements including Fe, Mn, Al and Si and then compared the results for those elements against assay data for the same. A strong correlation would tell us that the FPXRF results were reliable. Furthermore, to show the effect of simple sample preparation, we also analysed pulps of the same samples in the same way.The correlations were good for the all of the four elements of interest for the RC chip samples (R2 values between 0.82 and 0.9), and excellent for the pulps (R2 values between 0.89 and 0.998).The results also showed a direct correlation between sample preparation and improved quality of results with the FPXRF.The data showed allowed for two conclusions:1. the FPXRF can produce data from unprepared RC chips for Al and Si that, when compared with assay, is reliable for a fi eld application in drilling and grade control; and2. the greatest limitation to data quality is sample preparation.

Jul 11, 2011

By J Cronin, R Burgess-Limerick, T Horberry, L Steiner

"Automation offers the mining industry great potential for improvements in productivity and safety. However, the experience of introducing automation in other industries has been that the full potential of new technology is not always realised. Designers are surprised, for example, to find that automation does not eliminate human errors. Unwanted and unexpected consequences also arise if the introduction of automation fails to consider how people will adapt to the new technology. A focus on the technical aspects of automation is necessary but not sufficient for success. The potential for improvements in productivity and safety promised by automation will only be achieved if the joint cognitive system that emerges from the combination of humans and automation is designed to perform the functions required for system success. This case study describes the human factors issues associated with the introduction of automation generally, and describes a case study of the successful implementation of loader automation at Northparkes mine.Information obtained through a site visit and interviews with operators, safety staff and the project manager revealed the following strategies for successful design and implementation of the automation system: involve the people who will be impacted encourage constant communication between operators and designers provide operators with essential information avoid providing non-essential information provide the operators with flexibility empower operators to take action take advantage of the new possibilities automation provides.CITATION:Burgess-Limerick, R, Horberry, T, Steiner, L and Cronin, J, 2017. Mining automation human-systems integration – CMOC-Northparkes case study, in Proceedings 13th AusIMM Underground Operators’ Conference 2017, pp 93–98 (The Australasian Institute of Mining and Metallurgy: Melbourne)."

Oct 16, 2017

By T Napier-Munn, D J. Bradshaw, M Chauhan, L Keeney

An important aspect of geometallurgy is quantifying mineral processing attributes, which leads to improved orebody understanding. One of these attributes is flotation performance. Several methods have been developed as indicators for flotation performance, including batch testing leading to kinetic information and the standard grade-recovery curve. This paper makes a preliminary statistical comparison between a newly proposed geometallurgical batch flotation procedure and the æstandardÆ batch flotation test commonly used to measure flotation performance in the laboratory. The new test uses much less material than the standard test, and is much faster. It is concluded that the new method follows the final recovery of the standard method well, suggesting that it will be effective in reflecting ore variability for geometallurgical purposes. Comparison of the methods based on the full grade-recovery curve shows less agreement, but this may be due to the fact that the curve is sensitive to the particular experimental set-up and conditions, which make such comparisons quantitatively challenging. Further development work is therefore planned.CITATION:Chauhan, M, Napier-Munn, T, Keeney, L and Bradshaw, D J, 2013. Progress in developing a geometallurgy flotation indicator, in Proceedings The Second AusIMM International Geometallurgy Conference (GeoMet) 2013 , pp 201-206 (The Australasian Institute of Mining and Metallurgy: Melbourne).

Sep 29, 2013

Ok Tedi Mining Limited has recently completed the first phase of a trial to compare the performance of D26B Krebs cyclones in different configurations to the new Warman 650 mm CAVEX cyclones. From 1992, rougher flotation feed size has increased from the target d80 grind size of 150 ¦m with increasing SAG mill throughput. At high SAG mill throughput, operators have difficulty maintaining the target cyclone feed pressure and must increase the cyclone feed density, thus resulting in a coarsening of the cyclone split. Warman International have developed the CAVEX high capacity cyclone. The new CAVEX cyclones, when compared to the Krebs units appear to:produce a measurable increase in volumetric flow for the same pressure drop; maintain or decrease the proportion of coarse particles reporting to overflow; and lower the overflow density. In all plant trials to-date, the CAVEX cyclones appear to be superior to the standard Ok Tedi Krebs cyclones. Further testwork is planned to evaluate modified Krebs cyclones (with recent design improvements) against the CAVEX cyclones.

Jan 1, 2000

The optimisation and validation of shearer cutting methods is a time consuming engineering task. Many different parameters, of which not all can be controlled, can vary. The easiest solution, to increase the installed power and the longwall length, is not always the best. A different cutting method can increase the capacity without the need of new machines. The Department for Mining and Metallurgy Machinery at RWTH Aachen University therefore developed ProSL, the simulation tool for shearer and longwall operations. ProSL enables the engineer to create his own cutting methods and compare it with other methods. Machine-data can easily be varied to see the impact on the method. The research shows that sophisticated longwall methods increase the productivity of the system. The paper presents the results of the calculation with ProSL and shows how higher efficiency and lower costs can be achieved.

Dec 6, 2010

By J Coombes

"In today’s challenging climate of reduced staffing, limited funding and uncertain markets, we are called on to operate more productively and ‘be more innovative’. As an industry, we are quick to identify our practice areas as a mark of our role in the machinery of the mine value chain. We proudly note our profession – ‘geologist’, ‘mining engineer’ or ‘accountant’ – and demarcate our responsibilities and even our physical space. We even subdivide our disciplines into sacred entities such as ‘logging geologist’, ‘resource geologist’ or ‘structural geologist’ to prevent any blurring as though somehow the confusion will cost valuable disciplinary ground. How can we function professionally to heed the call to be more productive and more innovative?The purpose of this paper is to underscore what is expected from project evaluation, examine the ways in which we work as an industry and explore alternatives used in other industries and environments.The paper begins with a summary of project evaluation expectations and the ways in which disciplines typically interconnect when conducting project evaluations. Next, the paper examines alternative work frameworks and making a distinction between multidisciplinary, interdisciplinary and transdisciplinary frameworks. In-practice examples of these frameworks in alternative industries and contexts provide evidence for application as well as an opportunity to examine their pros and cons.The paper closes with a call to re-examine working practices in the mining industry, with a view to enhancing productivity and heeding the call for greater innovation.CITATION:Coombes, J, 2016. Transcending the mining discipline divide – multidisciplinary, interdisciplinary or transdisciplinary?, in Proceedings Project Evaluation 2016, pp 2–10 (The Australasian Institute of Mining and Metallurgy: Melbourne)."

Mar 8, 2016

By K Esmaeili, S Aziznejad

Impact-induced rock fragmentation is a mechanism that is commonly used for rock breakage in drilling and crushing. Additionally, rock fragmentation by blasting is frequently used in rock excavation operations. Experience shows that the presence of discontinuities can significantly influence the impact-induced damage and fragmentation of rock. Quantification of the response of jointed rock masses to impact loads is complicated by the fact that the available laboratory tests are mainly designed for aggregates or intact rocks. It can be argued that neither of these tests adequately represent a jointed rock mass. This paper presents the results of a series of numerical simulations used to investigate the influence of pre-existing discontinuities on the impact-induced fragmentation of rock masses. The methodology includes determination of the static and dynamic mechanical properties of a rock unit by conducting a series of laboratory tests on intact rock samples collected from a quarry in Canada. A 2D distinct element code, Particle Flow Code, was used to generate a bonded particle model in order to simulate both static mechanical properties (uniaxial compressive strength, elastic modulus, Poisson’s ratio and indirect tensile strength) and dynamic mechanical property (drop weight tensile strength) of the intact rock. The calibrated numerical model was then used to construct large-scale synthetic rock mass samples by incorporating discontinuity networks of different intensity into the bonded particle model. Finally, the impact-induced fragmentation inflicted by a rigid projectile particle on the jointed rock mass samples, simulated by a synthetic rock mass model, was determined. More fragmentation was observed for the rock mass samples with higher joint intensity.CITATION:Aziznejad, S and Esmaeili, K, 2015. Effects of joint intensity on rock fragmentation by impact, in Proceedings 11th International Symposium on Rock Fragmentation by Blasting, pp 377–384 (The Australasian Institute of Mining and Metallurgy: Melbourne).

Aug 24, 2015

By M R. Dehghan, H Mansouri, A Hakami, M A. Ebrahimi Farsangi, F Faramarzi

Today, it is accepted that rock fragmentation by blasting affects loading and hauling operations, and also directly influences on downstream processes such as crushing and grinding. In this research, the influence of rock fragmentation by blasting on the performance of three mills at Gol-e-Gohar iron ore mine No 1 was studied. Firstly, the fragmentation of conventional blast patterns in iron ore (5 × 6 m) was studied using image analysis and the performances of three mills were monitored. Then, a new blast pattern (4 × 5 m) was designed and nine blasts were carried out using this pattern. Increasing the powder factor form 1650 gr/m3 to 2480 gr/m3 by changing the blast pattern design showed that mill throughputs increase five per cent to 30 per cent for the new pattern.CITATION:Hakami, A, Mansouri, H, Ebrahimi Farsangi, M A, Dehghan, M R and Faramarzi, F, 2015. Study of the effect of blast pattern design on autogenous and semi-autogenous mill throughput at Gol-e-Gohar iron ore mine, in Proceedings 11th International Symposium on Rock Fragmentation by Blasting, pp 315–320 (The Australasian Institute of Mining and Metallurgy: Melbourne).

Aug 24, 2015

By R Dwyer, S Rea, W J. Bruckard, N McSweeney, R Holmes

"The innate ability of microorganisms to adapt to changing or inhospitable environments has often been exploited for industrial purposes and forms the basis of many current biotechnological processes. The ability of bacteria to adapt and adhere to specific mineral surfaces ensures that the energetic or nutritional requirements of the cell are met and often serves as a survival mechanism under unfavourable?growth conditions or conditions of stress. In this process, cells may rearrange or modify the macromolecules expressed on the cell surface itself or produce extracellular molecules, modifying mineral surfaces to render them more suitable for growth. The modifications that these molecules produce on mineral surfaces may result in changes to the surface charge and hydrophobicity of a mineral. As a result, these biomolecules may have some potential application as flotation collectors or modifiers.In this work, the effect of long-term exposure of Paenibacillus taiwanensis to goethite and common gangue minerals associated with Australian iron ores on the differential expression of membrane and extracellular proteins was determined. Both groups of proteins play a role in cell adherence to mineral particles. Cells were adapted to grow in the presence of each mineral over time. The proteins expressed on the cell membrane and the extracellular proteins excreted by the cell were isolated and analysed by two-dimensional polyacrylamide gel electrophoresis (2D gel PAGE). The outcomes of these studies are presented here and potential application of these products for flotation discussed.CITATION:Dwyer, R, Rea, S, McSweeney, N, Bruckard, W J and Holmes, R, 2013. Microbes and their metabolites - potential iron ore flotation reagents, in Proceedings Iron Ore 2013, pp 369-372 (The Australasian Institute of Mining and Metallurgy: Melbourne)."

Aug 12, 2013

By W P. Darcey

Jabiru Metals completed a feasibility study on the Jaguar Base Metal Project in July 2005. The study was based on conventional truck haulage via a decline. Conveyor haulage was considered but not in sufficient detail to provide a meaningful comparison. The current study investigates the cost and productivity of alternative ore transport systems for the Jaguar project. The options considered are conventional underground truck, conveyor, road train, rigid frame truck, monorail haulage and shaft hoisting. Shaft hoisting was not considered in detail due to the high capital outlay for such a relatively short mine life of less than six years. This study goes beyond the common approach of evaluating haulage systems in isolation; it includes development costs, timing of ore production and costs associated with mine services as well as administration and milling costs. The results of this study indicate that the best haulage option for the Jaguar project is conventional truck using the Hitachi AH400 trucks. The net present value (NPV) for this option is A$8.13 million higher than the next best option namely the Kiruna E635 electric truck. The conveyor option has the lowest operating cost per tonne of ore but the longer development time negatively impacts on its NPV. The monorail option is considered impractical due to the number and length of trains required to achieve production targets.

Mar 21, 2011

By Neville WE, Parkinson J

One of the earliest recorded risk management schemes was implemented by the boatmen of the Yangtze river some 4,000 years ago.. Between them they arranged for shipments to be split up in such a way that a load was divided five ways: if one was lost, then 80% of the shipment got through. Bottomry contracts were in vogue in Babylonian times with similar systems being used in India, in 60OBC and 4th century Greece. One of the first accepted mutual insurance ideas came in 1835 when a mill owner in America negotiated a lower insurance premium in return for installed fire safety measures. Approximately 20 years ago risk management as a philosophy was developed in the U.S.A., the philosophy followed to England and hence to Australia about 10 years ago. The business climate which induced the philosophy of risk management was that of "tight money". The definition of "assets" was then broadened to include earning capacity, skilled personnel and in a negative sense, a corporation's liabilities. In more affluent days losses were comfortably absorbed into the ongoing business expenses, the more prudent managers took out insurance which "covered everything" at a suitable premium. Statistics are available to indicate that a high percentage, (over 60%) of businesses which suffer massive plant damage due to fire, do not restart operations, or in the event of restarting have closed operations within the next 2 to 3 years - in spite of collecting an insurance payout.

Jan 1, 1986

By A Hewitt

Portland cement is the chief binding ingredient in mine backfill. In the presence of water, the chemical compounds within portland cement hydrate causing hardening and strength gain. During hydration, heat is generated. In certain cases, hydration heat may be produced significantly faster than it can be dissipated, which can create high temperatures in the underground environment. This paper presents the results of a series of investigations aimed at quantifying the heat generated by cemented backfill during hydration. Scaled stope models, instrumented with thermistors, were used in the investigation. Heat transfer to the hanging wall, orebody, footwall and cross-cut and production drifts was assessed during the backfill curing process and relationships between cement content, cure time, and heat generation were developed. The results of this work will assist mine operators in predicting the heat generated by cemented backfill and provide the necessary information to implement effective engineering control of heat in the underground environment.

Jan 1, 2005

By J M. Nel

Richards Bay Minerals (RBM) has recently undertaken an exercise to improve orebody basal definition. Older mineralisation bases (pre-2005) were highly erratic using old protocol reverse circulation (RC) (also known as Air Core) drilling and interpretation. The erratic nature of this estimation tool, resulted in impractical modelling towards the end of mineralisation (EOM), difficult mine design and unrealistic reconciliation. New protocol drilling, which includes high definition SONIC drilling data, has provided more data to be available for more accurate interpretation. Recent advances in drilling methodology has allowed for better penetration depths for SONIC drilling, which was previously restricted to approximately 80 m (pre-2005). This improved data set allows more emphasis on geological interpretation with factors such as lithology, slime content, and mineral species distribution. These factors when in unique combination enable more accurate and realistic EOM data points. These points are modelled into surfaces using conditional simulation techniques and result in a vastly smoother surface and consequently, a more representative resource.

Oct 5, 2011

Comparison of Grinding and Liberation Processes for Stalky Biomass Materials as a Prerequisite for Production of Energy Pellets with High Calorific Value Pelletising biomass, especially straw and stalky materials, requires a product specific size reduction and liberation. However, moisture content plays an important role in palletising and also affects the energetic properties of the biomass. The paper illustrates the characteristics of the mentioned type of biomass and specifies the necessities for production of energy pellets. Defined requirements for biomass energy pellets will be shown based on relevant standards. The work focuses on a comparative investigation of the straw fibres after grinding with hammer/impact mill and after the liberation of the straw fibres with twin-screw extruder (two different communition units). A traditional hammer mill as well as an hydrothermal process taking place in a twin-screw extruder were utilised. Results of the grinding and liberation of rye and wheat straw fibres are discussed based on a detailed particle characterisation (particle size and shape distribution). Besides high calorific value the main pellet quality parameters are mechanical stability, abrasion resistance and further combustion technical characteristics. The particle size distribution displayed optimum characteristics for the combustion processes to be carried out in a furnace. The durability of the pellets produced from straw fibres liberated with twin-screw extruder was comparatively better then that prepared with the straw fibres after grinding with impact mill. Particle size distribution, abrasion values and the strength characteristics showed a good correlation with each. The high presence of N and S would result in high NOx and SOx emissions, where as the high concentrations of Cl would corrode the furnace. These chemical properties of the straw would restrict its usage in small scale furnaces.

Sep 13, 2010

Rare-earth permanent magnetic roll separators, pioneered by our group a few years ago, have distinctly different operation characteristics compared to prior art electromagnetic separators of various types. Many new applications for dry high-intensity (or better: high-force) magnetic separation have been developed in a short time period. It has also been found that the new generation of separators generally are more efficient with regards to removal of weakly magnetic contaminants in glass and ceramic raw materials with minimum loss of valuable product compared to induced magnetic roll (lMR) separators. The latest development is in the area of production of clean magnetic concentrates at high recoveries. It is likely that the PERMROLLR magnetic separator will replace cross-belt and lift-type magnetic separators as a result of this most recent advance.   The paper will review the features of the PERMROLLR magnetic separator in comparison with other types of magnetic separators on the market and give examples on applications.

Jan 1, 1990

By I Jabou, D G. Blazak, L C. S Hogarth

The R70 test is a good indicator of coal reactivity to oxygen and is commonly used to provide a rating of propensity for self-heating. Tests performed by The University of Queensland Spontaneous Combustion Testing Laboratory have resulted in the development of a large database that shows the impact of coal quality on this parameter. From these results it is possible to infer an R70 value, which can be used to gain an appreciation of the intrinsic coal reactivity before it is even tested. However, any interpretation of R70 values must consider the influences of coal rank, mineral matter and moisture content to provide a better understanding of the spontaneous combustion risk of a particular coal.

Jan 1, 2005

By M J. Saynor, W D. Erskine an, D R. Moliere

The Jabiluka uranium mine was constructed in the Ngarradj catchment, a right bank tributary of Magela Creek in the Northern Territory. The Jabiluka Mineral Lease is adjacent to Kakadu National Park, near an area listed as Wetlands of International Importance under the Ramsar Convention and recognised under the World Heritage Convention. In the late dry season of 1998 and prior to the 1998 - 1999 wet season, a stream-monitoring program was implemented in the Ngarradj catchment to collect baseline data on sediment transport within the catchment to assess and proactively manage associated impacts caused by mining at Jabiluka. Stream suspended mud concentration, stream discharge and rainfall data were collected for four wet seasons (1998 - 2002) giving an almost continuous data set. The stream system has high natural variability dependent on rainfall intensity and subsequent discharge and pre-wet season fire distribution and intensity. In general, mud concentration is elevated at the commencement of the wet season until about February. This is caused by first-flush removal of surface material detached during the dry season by agents such as bioturbation (including anthropogenic activity), wind erosion and surface desiccation. Water quality trigger values downstream of the mine were derived using upstream percentiles and the before-after-control-impact, paired site design. Both analyses showed no observable impact from mine construction in 1998 or during the study period. However, the impacts of dry season fires could be clearly detected. The data set provides good baseline information for future assessment at Jabiluka and demonstrates the need to view measured parameter values on a catchment-wide basis with knowledge of rainfall, discharge and fire distribution.

Jan 1, 2004

By M Scoble, E Rubio

The re-engineering of manufacturing production systems has demonstrated the benefits from using production information for optimising processes. This paper explores the techniques and issues in the acquisition and analysis of mine production data for tactical decision making in production control. The use of information and operations management tools is presented in the context of block caving studies, with particular focus on the relationship between secondary breaking and LHD production performance.

Jan 1, 2000

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