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By C Artica

Two quantitative methods for Mineral Resource classification have been applied to a copper skarn deposit beneath a large open pit that is mining a world-class porphyry complex. A drill hole spacing study (DHSS) using the single block kriging method (SBK) and a conditional simulation method (CS) were applied to the skarn deposit and the results compared. Inputs to both processes included the proposed mining rate and stope designs to estimate the likelihood of achieving grade and metal production targets. Mineral Resource classification of the deposit considers the relative precision of tons, grade and metal predictions over quarterly and annual production periods. These relative precision estimates are calculated at 90 per cent confidence interval (CI). The SBK method represented the production period as a single large block. Kriging estimates were performed in the large block for various synthetic drill hole grids, and the estimation errors derived. The error was assumed to be normally distributed due to the large block size and quantity of samples, allowing CIs to be deduced. The CS method followed a conventional sequential Gaussian simulation workflow where grades were simulated with a 5 ft × 5 ft × 5 ft grid node spacing inside mineralisation domains. Each realisation was then averaged up to monthly production volumes represented by a combination of designed stopes, and the coefficient of variation (CV) for the averaged grade was calculated. CI on the relative precision of grade predictions were then deduced from the CVs. The two methods produced similar results; despite being calculated independently. CS results were used to report uncertainty in the proposed life-of-mine plan and highlight areas for additional drilling. SBK results were used as the basis for Mineral Resource classification as this method has been previously applied to the skarn deposit.

May 24, 2023

By Willett, Jacka

Group 3 were asked to discuss the treatment of spontaneous combustion. Before discussing specific cases we agreed that certain preliminary information should be available. The following questions are typical of the information which might be requested: 1. Have workmen been withdrawn? 2. Have gas samples been taken? 3. Is the mine gassy? 4. What are the details of water supply? 5. Are mine plans available? 6. What equipment is available? We discussed treatment in four different circumstances as follows: 1.

Jan 1, 1973

By K Eglinton

The extractive industries response to community engagement due to social and political pressures in the 1980s and 1990s was the starting point of development leading to the modern function of corporate social responsibility.Challenged by communities who have greater access to information, demand greater transparency and responsibility of corporate organisations and who possess greater awareness of the communities they participate in, the mining sector faces another step change in how it approaches and integrates corporate social responsibility, transparency and engagement.Mining is seeking reserves of lower grades, in more sensitive environments and in countries with minimal transparency and governance. Not only are the locations changing but so to the stakeholders to engage with and issues to contend with. An increasingly savvy opposition, including not just the ‘green hippies’ but the Gen-Ys interested in the wider sustainability debate and Baby Boomers moving to life style environments, are now questioning mining’s behaviour and encroachment into ‘their space’. Issues including effect on lifestyle amenity, property value, energy efficiency, social provision; concepts such as ‘doing more with less’, participatory engagement, increasing transparency and balancing economic, environment, cultural and social aspects are becoming the norm.The traditional model of supporting local communities, communicating plans and providing employment, community investment and indigenous support programs is not enough. Our industry faces challenges on multiple fronts. It must now be able to address these from a personal/community perspective if it is to remain relevant within communities and play a role in addressing the global sustainability issues.This paper draws on corporate social responsibility trends, integrated functions and implementation approaches through the application of activities within Newmont operations across Asia Pacific.The approach presented works on the philosophy that communities do not necessarily have to like what we do, but should be able to identify and recognise the way in which we involve them in decision making, communicate our intentions and respond to issues.

Nov 22, 2011

By R Dimitrakopoulos, K Kawahata, L Montiel

A method that optimises mining complexes that are comprised of multiple processing destinations, open pits and underground operations is presented. Mining, blending, processing and transportation decision variables are simultaneously optimised while accounting for geological uncertainty. The method uses a simulated annealing algorithm at different decision levels to generate a stochastic-based extraction sequence and processing policies. A case study shows its ability to generate a higher net present value while facing a reduced amount of risk when compared to traditional optimisation methods.CITATION:Montiel, L, Dimitrakopoulos, R and Kawahata, K, 2014. Globally optimising open pit and underground mining operations under geological uncertainty, in Proceedings Orebody Modelling and Strategic Mine Planning Symposium 2014, pp 201–212 (The Australasian Institute of Mining and Metallurgy: Melbourne).

Nov 24, 2014

By S Juras

The terms measured resources and proven reserves denote the highest level of estimation confidence in all of the major classification schemes. But what do they really bring to today’s project or mine with respect to production planning and expectations? Initial reserve declaration does not need measured resources, just indicated resources. Economic viability of a project is assessed on total reserves with nary a bonus for the amount of proven reserves. Production plans are based on grade and tonnage goals that may only coincidently correspond to proven reserves. So are the measured and proven categories still relevant? Historically, and almost exclusively in underground mines, companies only allowed mining in areas of proven reserves. Some companies still follow that philosophy. But many others will mine a mixture of probable and proven reserves without hesitation. Also what of the undeveloped project in a new district – what is to be made of their declared measured resources and proven reserves? Measured resources are commonly set either by some type of proximity to data scheme or a matter of ‘feel’ based on the qualified person’s experience. The parameters for reserve conversion focus on the project as a whole and then a portion becomes classified as proven reserves almost solely based on whether the resource category is measured. So should the mining industry continue to use these categories of resource and reserve classification? This paper will present arguments about making these categories once again more relevant. A more disciplined usage of these categories may re-introduce their relevancy in public disclosures of resources and reserves. As well a more consistent usage in operations may lead to increased confidence in managing production targets and costs.

Aug 22, 2011

By D H. Laubscher

The in situ rock mass rating system û IRMR - leading to the mining rock mass rating system - MRMR - for jointed rock masses has been used (and abused) in mining operations around the world for the past 27 years. Despite the recent development of elaborate design procedures and computer-aided design packages, MRMR remains one of the most versatile and practical mine design systems available. It is important to realise that the rock mass classification system should not be replaced but rather complemented by more sophisticated and detailed design procedures. The classification system is not only the æcrudeÆ method used for initial assessment (as described in some geotechnical literature) but also in many respects a very effective and practical engineering tool. MRMR could, and should be used during the entire stage of mine life as an integral part of the design process. The objectives of this paper are to illustrate using practical case histories from the past decade, some of the pitfalls of the MRMR classification system, to clarify certain misconceptions in its application and update its mining application.

Jan 1, 2000

By J E. Everett, F Grobler

This study considers realistic data for a planned open pit iron ore mine, but is applicable to any open pit situation. By interpolating drill hole data, grades are generated for a rectangular block model. Each blockÆs grade designation vector has components for each analyte (chemical element or compound) influencing ore value. Interpolation by means of geostatistical kriging leads to each block being assigned its expected value, and thus underestimates the overall grade variability. Alternatively, interpolation by means of conditional simulation is a method that implements random sampling from an infinite population of solutions. Each conditional simulation has appropriate overall grade variability, but estimating any blockÆs mean and variance requires sampling from multiple conditional simulations. For a block model, an ore/waste selection criterion maximises the expected tonnage at a target grade. This criterion is a linear composite of the grade components, with positive coefficients for the beneficial analyte (iron) and negative coefficients for the deleterious analytes (such as silica, alumina and phosphorus).Although conditional simulation gives the same expected grade as kriging for each block, the expected maximum tonnage of ore selectable at a target grade may differ from that obtainable from the kriged solution. We apply the linear composite selection criterion to each of 25 conditional simulations, as well as to the kriged block model. The resulting distribution of product tonnage is confirmed to have an expected tonnage that is over 20 per cent greater than that of the kriged model. The method also enables a selection probability to be computed for each block, and thus a probabilistic pit boundary distribution to be identified and used in mine planning. Proposed extensions will consider risk-based scheduling of the multiple selection solutions through minimisation of a derived æstress factorÆ and treating the mining process as an iterative system with actual or artificial ædepletionsÆ modelled in line with the mine plan, using the updated state (with new information) to re-evaluate the mine plan for subsequent periods.CITATION:Everett, J E and Grobler, F, 2013. Risk-based ore selection from conditionally simulated block models, in Proceedings Iron Ore 2013 , pp 149-156 (The Australasian Institute of Mining and Metallurgy: Melbourne).

Aug 12, 2013

EIA is a test of a development proposalÆs legitimacy and asks two questions: not only æis the proposal competent?Æ but also ædoes the proposal have moral authority?Æ For reasons of miningÆs historic importance and of a scientific and technological industry culture, traditional EIA has focussed on the first on these, an increasingly misplaced priority in a changing world.This paper explains why competence alone is not enough and examines the second of the two questions: what is meant by a projectÆs moral authority, why does it matter, why has it taken so long to become an issue and what, in practical terms, can project proponents do about it.

Jan 1, 2004

By L Tatnell, R Mackay, A Tolooiyan

The multi-reversal direct shear test (MRDS) method is commonly used to measure the residual shear strength of soils. However, when the standard direct shear (DS) apparatus is used, the MRDS method is prone to two major sources of error: load cap tilting and specimen loss. These two sources of error can cause erratic behaviour in the residual shear strength curve, making it difficult or even impossible to determine the correct residual shear strength value of the specimen being tested. This paper presents the results of new modifications to the standard DS apparatus that prevent load cap tilting and specimen loss. Consolidated drained testing was performed on highly-over consolidated cohesive soil samples from a Latrobe Valley open pit mine, with results obtained from the modified DS apparatus showing a great improvement in the residual shear strength profile compared to those obtained using the standard apparatus. Large numbers of reversals (up to 14) conducted on a single specimen in the modified DS apparatus showed no notable load cap tilting and no specimen loss occurred. The modifications are easily applied to the standard DS apparatus, and analysis and correction of the data are simple.CITATION:Tatnell, L, Tolooiyan, A and Mackay, R, 2014. Measurement of residual shear strength using a modified direct shear apparatus, in Proceedings AusRock 2014: Third Australasian Ground Control in Mining Conference , pp 425–434 (The Australasian Institute of Mining and Metallurgy: Melbourne).

Nov 5, 2014

By R A. Anand, N N. Viswanathan, M M. Pande

Slags are the most voluminous solid by-products generated in pyrometallurgical operations, and, as such, finding an application for these oxidic materials is pertinent to maintaining resource efficiency. In particular, pyrometallurgical copper production is associated with high slag rates, typically ranging from 2.2 to 3.0 tons of slag per ton produced copper, which necessitates slag valourisation. A possible application for these iron silicate slags is as supplementary cementitious materials (SCMs), which effectively lowers the CO2 emissions per ton of cementitious material. Although utilising iron silicate slags as SCMs has been studied in previous work, the scientific literature has limited data on the effect of composition on the inherent reactivity in cementitious systems. More specifically, no reports on the impact of FeO/SiO2 ratio have been presented in previous publications. Therefore, the present study aimed to isolate this parameter in a synthetic FeO-SiO2-Al2O3-CaO-MgO-Cr2O3 system. Since the amorphous content is a pertinent parameter for SCMs, a high-temperature confocal laser scanning microscope (HT-CLSM) was utilised to assess the crystallisation behaviour at continuous cooling conditions. Furthermore, high-temperature rheological experiments were conducted to measure the viscosities of the slags in relation to the crystallisation behaviour. The experiments showed that depolymerising the slag by increasing the FeO/SiO2 ratio generated a less viscous slag, which showed higher tendencies for crystallisation. Furthermore, experiments assessing the inherent reactivity as an SCM showed that depolymerising the slag by increasing the FeO/SiO2 ratio as the sole independent parameter generated an initially more reactive slag. However, replacing SiO2 with FeO was found to negatively affect the reactivity as measured over seven days within the tested compositional range.

Jun 19, 2024

By J J. Grobler

The George Fisher Underground Mine at Mount Isa applies the long hole open stoping methodology. During the reconciliation process of transverse stopes in the George Fisher North mine it was identified that excessive underbreak was regularly experienced, with the major contribution coming from the toe area inside the stope.While over break and the resultant dilution was well investigated and well understood, limited work was done on underbreak improvement. It was decided that a re-engineering process would be followed in an attempt to improve results. The prevailing stoping practices were scrutinised and the possible causes were listed.Some of the identified causes were design, drilling accuracy, equipment condition, mucking practices and direction of firing. It was identified that in most instances the underbreak was initiated in the slot area of the stope during the first firings. Once this happened, it was impossible to get good recoveries on the rest of the stope. The slot area was carefully scrutinised and the blasting practices were changed individually.During the following two years several different strategies were trialled to increase the toe recoveries. The results indicated an overall improvement of six per cent reduction in underbreak on average, by ensuring drilling accuracy and changing the direction of firing. The economic significance of these results outweighed the time and additional work load expended to establish the cause of the problem. This paper outlines the continuous improvement process undertaken to identify and rectify the major contributing factors to the problem. It also presents a set of recommendations to be followed in order to achieve positive results.

Mar 21, 2011

By L Dubron

This study details a mineralogical and textural characterisation of West African iron ores with an emphasis on their behaviour during mineral processing. By means of both qualitative and quantitative characterisation, a simulation of the beneficiation process applied to these iron ores is performed. A series of different analytical tools are used, including:X-Ray Diffraction (XRD) for qualitative mineralogical analysis;• qualitative optical microscopy (phase identifi cation, description of micro-textures) and (semi)• quantitative optical microscopy (counting of particles, phases and textural types); and• chemical analysis.All the information provided by these analytical methods are combined into a quantitative mineralogical and textural analysis, here called ‘modal analysis’, which enables us to simulate the capability of West African iron ores to be benefi ciated by magnetic and gravimetric separation techniques.On one hand, both qualitative XRD and optical microscopy have revealed the presence of the following mineralogical phases: magnetite, haematite, goethite and quartz. On the other hand, the chemical analyses provide us with quantitative inputs expressed as oxides. We have converted the oxides into mineralogical contents expressed as magnetite, haematite, goethite and quartz. In this way, we build a simple quantitative mineralogical analysis.Beside this, the semi-quantitative approach of the characterisation by optical microscopy also provides us with a liberation study, enabling us to split the gangue-bearing content between two types of particles:1. liberated gangue-bearing particles, and2. composite particles composed by both iron (oxhydr) oxides and gangue-bearing minerals.We have assumed that we could anticipate the behaviour of these two kinds of particles through a mineral process, by simulating the removal of at least the liberated particles of gangue. Optical microscopy also revealed a trend in the weathering profi le of the Tokadeh ore horizon with a decrease from bottom to top of magnetite and an increase of both goethite and martite showing a higher level of oxidation and hydration in the upper ore horizon.We have applied this removal extent upon the quartz content of the mineralogical quantitative analysis and we have re-calculated the quantitative mineralogical analysis considering the expected decrease in the quartz content. Finally, by converting the re-calculated (oxhydr) oxides contents into iron grades and summing them, we do obtain a fi nal simulated iron grade for the upgraded products.

Jul 11, 2011

By D L. Kennedy

Many aspects of the physical layout of manufacturing plants and storage facilities for explosives are governed by so-called quantity-distances tables. Both the British and the American tables were originally derived from an analysis of the injuries and the building damage documented by an early 20th century compilation of significant accidental explosions. However, progressive changes in explosive process technology and in building techniques have reduced the relevance of much of this historic data set. Extensive scientific research has been conducted over recent decades to characterise the potential injuries and damage from accidental explosions under more modern conditions. This presentation will showcase some of this research.**This is an abstract only. No paper was provided for this abstract**

Nov 8, 2011

By C Harwood

Underground coal mines in the United States are in the process of completing installations for tracking and communication systems, mandated by Congress after a number of recent coal mine disasters. Yet, evaluation, modelling and testing of such systems has lagged due to legislated changes, abruptly introduced into the coal mining industry. System installation in a wide array of mine types, configurations, layouts and characteristics has provided a wealth of information regarding their potential in underground environments. Data collected from numerous installations for a variety of systems can be used to further define true capability and accuracy of communication and tracking packages. This paper describes a uniform means of evaluating the performance of a communication and tracking system. Several performance measures are proposed and described. These measures can also be predicted using an interactive software program. This program predicts the signal propagation, given the input mine characteristics and layout, with numerical and visual feedback. New or alternative system installations can also be more accurately designed to potentially minimise initial system cost and time required for trial and error installs. The focus of this research is to develop tools and protocols that can evaluate and measure the effectiveness of installed underground communication and tracking systems.

Nov 22, 2011

By S Bourke, R Stone, B Hill

Since Jameson Cell flotation technology was first installed in a coal flotation application in 1988/89 at Newlands Coal Handling and Preparation Plant (CHPP) there have been fundamental improvements to its design which has led to its current status as the leading technology in Australia for fine coal flotation. These improvements, which include key hardware modifications, consist of the re-development of the orifice plate to produce considerable increase in wear life and reduction in power consumption for a given air entrainment and a significant increase in the amount of air that is entrained. Modifications to the downcomer allow maximisation of residence time and air entrainment while changes to the feed and air distribution system allows a reduction in installation cost and a reduction of solids ingress into the air line. Additionally, operational improvements such as the use of recycle to maintain constant flow to the cell feed are discussed. The recent installation at Hail Creek in the Bowen Basin, which consists of three B6000/20 Jameson Cells (6 m diameter bottom-fed distributor with 20 downcomers) will be reviewed as a case study. The latest design and operability of the cells are summarised and compared against one of the original designs at Riverside CHPP also in the Bowen Basin.

Jan 1, 2005

By J Vann, S Dunham, M Job

Two-dimensional (2D) estimation approaches have significant advantages over three-dimensional (3D) approaches when dealing with a narrow vein- or layer-like geometry. The main motivation for 2D estimation is that bias due to non-additivity of grade is avoided. The various aspects of 2D estimation are illustrated by use of a case study from the 1A Shoot Nickel deposit at Leinster, Western Australia. The width of the 1A mineralisation is variable, and so are the angles of drilling intersection. Consequently, the variable of interest (in this case nickel grade) is not suitable for direct kriging because it is defined on non-uniform support. However, grade can also be defined as the ratio of two variables that are suitable for direct kriging: thickness and accumulation. In the 2D approach, tonnage equates to thickness and metal equates to the product of grade and thickness, also called æaccumulationÆ. In the simplest approach we can independently krige accumulation and thickness and derive the grade by the ratio of the two resultant estimates. The thickness and accumulation variables must be in a consistent projection orientation, for example a horizontal projection in the case of steeply inclined mineralisation like 1A. Because the density is not constant across the 1A (and most other) deposits, the issue of density weighting is also discussed. The impact of the correlation between grade and length, or grade and density are important issues in implementation of 2D estimation. The circumstances under which these correlations need to be taken into account (by co-kriging) are reviewed. Finally some comments are made on the final use of the resultant 2D estimate for mine planning purposes.

Jan 1, 2003

By A Melkumyan, F Ramos

This paper addresses the problem of prediction of grade variables over volumes (block estimation) for an autonomous mine. Resource estimation is usually concerned with the prediction of the quality of material over volumes (blocks in resource models). This problem is tackled by developing Bayesian block estimation with the Gaussian processes (GPs) framework. GPs are commonly used for nonparametric regression and classification and offer an elegant solution to deal with incomplete knowledge and information. A GP is defined by its mean and covariance function. The parameters of the covariance function can be learnt by maximising the marginal likelihood of the data. This offers a way of automating the covariance fitting process, while at the same time allowing for an assessment of how well the covariance function fits the data. Within the GP framework the calculation of the average grade over a volume can be performed using Bayesian quadrature, which treats an integral as a random variable. First, it is demonstrated that the block kriging equations in geostatistics are the same as Bayesian quadrature. Then, it is determined when closed form analytical solutions for the integrals are possible and quadrature approaches for approximations are briefly discussed.

Sep 26, 2011

By A Dix

Fire suppression systems are but one of the many technologies currently available to manage operational tunnel risks. However, the actual reasons for their use are often shrouded in mischievous discussions of the marketing variety.The international tunnelling community still stands divided on the merits (or otherwise) of fire suppression systems. For some the debate focuses on their cost compared to the theoretical benefits they bring to human safety.Long standing concerns about their potential adverse effects in an emergency are often at odds with the experience from tunnels which use them. High installation and operational costs are cited as reasons not to use them, yet toll road operators and insurers increasingly use them as a risk mitigation strategy for toll revenue protection.Fact or fiction, myth or reality, should such systems be seriously entertained or are they just another expensive gadget in the escalating array of expensive toys for modern tunnels? Ultimately this presentation argues that they have their place as a risk mitigation measure to achieve a range of objectives. The exact circumstances for their use ultimately fashioning their design and operational characteristics. This is an abstract only. No paper was prepared for this abstract.

Mar 8, 2011

By B Belle

In a deep, gassy predrained coalmine, ventilation and goaf drainage systems act as critical controls to manage longwall (LW) panel return gas levels. The goaf capture efficiency of most LW panels ranges from 45 to 85 per cent based on the gas domain at respective workings. Recent operational experiences have indicated that 50 m goaf hole spacing is optimal for management of high production retreat gassy LW panels, where the probability of goaf hole failures are frequent. Due to the horizontal stress direction geotechnical issues, goaf hole failure just behind the LW face is a recurring challenge resulting in significant and immediate increases in LW panel return gas levels. This paper presents a successful implementation of an innovative LW tailgate (TG) road cut through seal goaf fan/venturi system. The system incorporated a 17' (400 mm cased) hole drilled to 320 m deep in a perimeter roadway on a retreating LW TG road drawing the working seam horizon goaf gas behind the perimeter of seals. The surface goaf fan/venturi system was aimed to safely exhaust the LW deep goaf gas and thus withhold the goaf stream spillage to TG drive area and reduce the panel gas load by controlled operation of the system using continuous monitoring of CH4, CO and O2 levels. This control philosophy was made operational without impacting the use of the perimeter inbye ventilation shaft used for mine cooling and providing additional ventilation dilution capacity. The instantaneous reduction in TG gas levels of up to 0.3 per cent was observed even when the LW was 300 m away from the c/t seal goaf hole. Success of this concept TG seal goaf gas control system used even when the LW was 1300 m outbye has become an inventory of additional control for future deep and long LW blocks. This paper attempts to share the design process in addressing other risks and desired outcomes in managing the LW gas levels.CITATION:Belle, B, 2015. Innovative tailgate mobile goaf gas management in two gate road longwall panels – concept to implementation, in Proceedings The Australian Mine Ventilation Conference, pp 31–40 (The Australasian Institute of Mining and Metallurgy: Melbourne).

Aug 31, 2015

By T M. Campos, H A. Petit, L M. Tavares, R Olympio

Much practical experience has been gathered in the last 30 years of application of high-pressure grinding rolls (HPGR) integrated with ball milling in size reduction of fine iron ore concentrates. The company Vale S.A, in Complexo de Tubarão (Brazil), was one of the pioneers applying the technology prior to pelletisation with an outstanding size reduction energy efficiency in the circuit and a significant increment in the specific surface area of the product. Recent studies by the authors demonstrated benefits of modelling and simulation to improve the performance of HPGRs in this particular application, with the model being able to describe HPGR performance under different operating conditions and under variations of feed size distribution. Despite these important advances, this modelling approach has only been used offline and under steady-state conditions. The present work applies the modified Torres and Casali model proposed by the authors in pseudodynamic simulations. The ability of the model to predict the characteristics of the product in real-time is evaluated using data available online for the pellet feed preparation circuit. Results demonstrated the model capabilities to map the physical operation and give a realistic representation of the process. Additionally, the model is demonstrated to be able to support the pellet feed production by providing extended real-time information of the process, making it a useful tool for improvement of the operational strategies and process stability.

Aug 24, 2022