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By H Lieberwirth, M Pfeifer, F Heinicke

HPGRs (high pressure grinding rolls) have been developed within the last decades for energy efficient processing of a wide variety of ores. Special interest has been raised by projects increasing the capacities of processing plants by installing HPGRs prior to ball mills. Bond ball mill tests have been used for decades as a base for ball mill dimensioning in mineral circuits. For final CAPEXOPEX considerations of the processing circuit, one key question is about the level of grinding energy split between HPGR and downstream grinding stages. This is especially interesting if the downstream process comprises multiple grinding stages combined with separation steps. The paper presents investigations on grinding energy consumption, size distribution and microfracturing of HPGR products, which affect the efficiency of the whole comminution and sorting process.

Aug 24, 2022

By Larry Hopkins

The molten metal circulation pump has become a staple for melting aluminum in reverberatory furnaces. The forced convection that is created in the melt efficiently provides circulation while dramatically improving melt rates, lowering fuel consumption, extending refractory life, and providing metallurgical homogeneity. Two metallurgical guidelines that are important to many casthouses are molten metal inclusion levels and hydrogen gas content. In order to improve molten metal quality, furnace and casting practices must 'manage these molten metal defects, Today specialized in-line degassing and filtration equipment is used downstream of the furnace to accomplish these tasks. In contrast, the molten metal gas injection pump has metallurgical contact time in the process for hours during the charging/homogenization cycle. The qualitative benefits of employing a gas injection pump to "pre-clean" are outlined and discussed against historical empirical information obtained with alternate methods. Further, a recent study quantifies the merits of this gas injection technique as an effective molten metal quality improvement tool. Specifically, the effects on inclusion level as determined by PoDFA?, gas content as determined by A1SCAN? sampling and alkali metal content as determined by spectrographic analysis are examined in relationship to various gas feed compositions and flow rates.

Jan 1, 1995

By J. Lu, D. G. Ivey, H. Henein

Microalloyed steels are widely used in the oil and gas industry. They are a class of high strength, low carbon steels containing small additions of niobium (Nb), titanium (Ti), molybdenum (Mo) and/or vanadium (V). These steels have good strength, toughness and excellent weldability, which are attributed in part to the presence of nano-sized carbides, nitrides and carbonitrides. In the pursuit of developing higher strength microalloyed steels, it is of great interest to quantify the size, distribution, volume fraction and chemical speciation of these precipitates. However, characterization techniques suitable for quantifying fine precipitates are limited. Possible characterization techniques include SEM, TEM and matrix dissolution. A comparison is presented of the various techniques.

Jan 1, 2005

By Angus Maxwell, Jacob Grasmick

As the tunneling industry continues to adopt Tunnel 4.0, digital twins of the tunnel construction site are becoming standard requirements for tunneling projects. However, the benefits of these remain unproven to many practitioners. The paper discusses the various implementations of digitalization and describes efforts to combine all data types to analyze the relationships between influences, predictions and performance in a single digital platform. This includes data pertaining to investigations, design, construction, monitoring and post-construction asset performance and management. Based on 16 years of global tunneling projects the paper aims to quantify the tangible and intangible benefits of such systems. Using a number of real examples, the paper describes where opportunities were taken and where they went unrealized. Challenges and considerations for both procuring and developing these digital twins are also discussed.

Jun 13, 2021

By Florian Kongoli

"Lime ferrite" slag with limited silica content has proven to be a valuable choice in the modem processes of copper smelting and converting due to several advantages that this slag offers compared to classical silicate slags. Nevertheless the liquidus surface of this slag has been experimentally measured only at low oxygen potentials such as in equilibrium with iron or hear it and in air. Although most of the smelting and converting processes that use this slag occur at intermediate oxygen potentials, the liquidus surface of this slag is not known at these conditions and the effect of oxygen potential and silica has not been correctly understood. This has brought some confusion in literature as well as in the industrial practice. In this work the liquidus surface of the calcium ferrite slags has been quantified by the means of a new thermophysicochemical model and a new type of liquidus surface diagrams which are very convenient for any industrial process that uses calcium ferrite slags. These diagrams can be easily used to select the lowest liquidus temperature of calcium ferrite slags at a minimum cost and can help design several fluxing strategies in copper smelting and converting processes. The effect of the oxygen potential and silica is also quantified and important industrially related conclusions are drawn.

Jan 1, 2003

By Florian Kongoli

"Lime ferrite" slag with limited silica content has proven to be a valuable choice in the modem processes of copper smelting and converting due to several advantages that this slag offers compared to classical silicate slags. Nevertheless the liquidus surface of this slag has been experimentally measured only at low oxygen potentials such as in equilibrium with iron or near it and in air. Although most of the smelting and converting processes that use this slag occur at intermediate oxygen potentials, the liquidus surface of this slag is not known at these conditions and the effect of oxygen potential and silica has not been correctly understood. This has brought some confusion in literature as well as in the industrial practice. In this work the liquidus surface of the calcium ferrite slags has been quantified by the means of a new thermophysicochemical model and a new type of liquidus surface diagrams which are very convenient for any industrial process that uses calcium ferrite slags. These diagrams can be easily used to select the lowest liquidus temperature of calcium ferrite slags at a minimum cost and can help design several fluxing strategies in copper smelting and converting processes. The effect of the oxygen potential and silica is also quantified and important industrially related conclusions are drawn.

Jan 1, 2003

By Mark F. Sindelar, Yi Luo, Hua Jiang, Michael T. Shook

"Convergence of roof and floor in underground mine openings is a common occurrence. This convergence not only adversely affects the ability of workers, equipment and supplies to travel through the mine, it also reduces the effectiveness of the mine ventilation system, which is essential for the dilution of methane gas and airborne respirable dust. While installing secondary standing supports to control floor and roof convergence, such supports, by nature, partially obstruct a portion of the airway. These added obstructions inhibit the ability of the ventilation system to operate as efficiently as it could by increasing the resistance in and reducing the cross-sectional area of the airway.This study introduces and demonstrates the benefits of The Eye CAN™ standing roof support, which controls floor and roof convergence and is less obstructive to air flow than conventional wooden cribs. Laboratory findings show that the normal resistance of a supported lined airway is reduced by using this new product from Burrell Mining Products, Inc., while providing the same roof support characteristics of an established product-The CAN®. Load vs. displacement curves generated from laboratory tests demonstrated that this new product behaves with the same roof support characteristics as others in The CAN product family. Ventilation data gathered from a simulated mine entry was then used for computational fluid dynamics (CFD) modeling. The CFD analysis showed an improvement with The Eye CAN versus other accepted forms of standing roof support.This proof-of-concept study suggests that, when using this new product made by Burrell Mining Products, Inc., not only will the convergence from the roof and floor be controlled, but airway resistance will also be reduced.INTRODUCTIONOne of the basic elements of underground mining is the necessity to support the mine roof. It is well-known that easier reserves have been mined so that today's underground mines present challenging conditions. Factors influencing roof support decisions include mine depth, mining method, overburden composition, and agency regulations. Mining engineers, therefore, have to balance three objectives: safety, engineering, and cost. While safety is obviously paramount, and engineering often complements safety, the cost effectiveness of any product, method, or device warrants additional consideration in today's harsh business climate. Avenues for adaptation and improvement are found at the intersection of the three objectives."

Jan 1, 2016

By E. Brouillette

Difficult operating and mining conditions such as low visibility, difficult roadbeds, fast cycling, small openings, and sharp corners create high demand for LHD manoeuvrability and operator dexterity. Operator experience and patience is especially solicited to fill the bucket rapidly and efficiently and performance can be particularly affected by the skill level of individual operators. Teleoperation and automated loading are viewed as options to improve overall equipment and operation performance in certain mining conditions. Comparative statistical measurements of autoloading performance in different production environments at Noranda demonstrate an increase in bucket filling efficiency and a reduction in filling variance, allowing LHD operation to be more consistent and within manufacturer specifications. Consequential cost savings and productivity increases are demonstrated to be transferable to other mining situations.

May 1, 2003

By J. Hadjigeorgiou, T. R. Stacey

This paper introduces the Quantified Value-created Process (QVP), a decision-making process for use in mine design and operation. The implementation of the QVP is founded on a ten-step rock engineering design process and a ten-step strategic planning process. The potential of this approach is demonstrated by examples of value created as a result of good research, design, and planning. The QVP is divided into two parts, namely, a ‘planning the process’ section and an ‘implementing the process’ section, and can be considered to be an extension of the risk approach. All costs, direct and indirect, associated with a significant mining decision (design, operational, investment) must be quantified in advance of committing to that decision, to determine the value that will be created in the short, medium, and long terms. Ethical values, associated with health, safety, the environment, public perception, and social aspects, may be difficult to quantify in economic terms, but must nevertheless also be considered. In contrast with a traditional risk approach, the QVP will identify the upside, and allow executives to make more informed strategic decisions. In this context it is essential to actively engage upper management in the decision process.

Feb 2, 2022

By S. Kemball-Cook, D. Heinze, A. Kornberg, M. Harmon

Climate change presents risks to mine infrastructure, operations and long-term obligations to protect environmental conditions. Management strategies and design of infrastructure and containment systems based on past or current climate conditions may be inadequate in the future if changes in climate are not taken into account in planning for mine operations, decommissioning, closure and post-closure. Data-driven assessments using climate model projections of the future can be used to quantify: • Changes in site-specific risks to mine structures, access, containment facilities, operations and staff safety. • Changes in vegetation and water balance/chemistry, and potential for acid mine drainage, erosion and design failure. Climate- and weather-related risks are a serious threat to the mining industry, but risk transfer solutions can alleviate these vulnerabilities. Mining companies can protect themselves through bespoke solutions which provide operators, investors and buyers with protection against weather-related disruptions to operations by hedging to smooth revenues. Using risk transfer structures to mitigate climate risks is a mechanism that is available to all types of mining operations world-wide. In this paper, we describe methods for evaluating site-specific climate change impacts and developing risk transfer solutions to mitigate their effects. EVALUATING MINE RISKS FROM CLIMATE CHANGE The best available tool for understanding potential future changes to the earth’s climate system are global climate models (GCMs) (IPCC, 2014). GCMs are computer simulations of the climate system which include the atmosphere, ocean, land surface, cryosphere and biosphere. Because of the computational demands of running a global model for many decades, the spatial resolutions of the GCM grids are necessarily coarse, typically on the order of 100-300 km. GCM data are therefore suitable for evaluating future physical risks on global or continental scales, but may not be appropriate for evaluating location-specific risks (e.g. Kotamarthi et al., 2016). For site-specific, quantitative physical risk assessment, GCM projection data are “downscaled” or adapted for use at the local level using statistical techniques together with observed data (statistical downscaling) or using high-resolution regional climate models (RCMs) that focus on a single geographic region and have spatial resolutions of 10-50 km (dynamical downscaling). Downscaling bridges the gap between the GCM scale and regional/local scale. Through the downscaling process, new information is added to the GCM output from observations and/or RCMs, resulting in patterns for weather variables that are more consistent with local terrain and weather influences. Downscaled climate change projections for the mine site are selected considering mine location and geography, the availability of local observations, and the performance of the downscaling method and global/regional models used to develop the projection in simulating the variable under study. Where possible, we use projections from an ensemble of global and regional model runs spanning a range of future greenhouse gas (GHG) scenarios.

Jan 1, 2019

By Mustafa Kumral

Monte ? Carlo simulation is often used to assess the risks associated with uncertain variables in mining operations. The success of Monte-Carlo simulations depends upon reproducing the dependencies among variables to some extent. However, some variables may exhibit different dependency patterns. In these cases, classical techniques for dependency quantification cannot capture dependencies. As an alternative, the copulas allow modeling nonlinear dependencies. Furthermore, any choice of marginal distributions can be used. Especially, for the data, which is sensitive to extreme case such as financial crisis, the copulas arise as a means to reproduce the correlations among variables. In this paper, the copulas are introduced to mining practitioners using Monte-Carlo simulations for risk assessment. Then, a case study is given to show the superiority of the copulas over classical techniques using ModelRisk Software. In conclusion, it was observed that the copulas enhance the quality of Monte-Carlo simulations by capturing variable dependencies.

Aug 1, 2013

By E Amini, M Scott

Grade Engineering® involves the planning, integration and operation of coarse preconcentration techniques to reject uneconomic material as early as possible in the mining value chain to improve the quality of ore delivered to mineral processing activities. These preconcentration techniques include screening for natural and induced deportment of grade to finer size fractions during blasting and coarse breakage, sensor-based measurements of grade and mechanised sorting at particle or bulk scales and coarse gravity separation. Over the last decade, the Cooperative Research Centre for Optimising Resource Extraction (CRC ORE), with the support of its participants, has developed a framework for the holistic evaluation of economic and production impacts attributable to these preconcentration techniques. The framework combines the characterisation of preconcentration responses, geostatistical modelling, process modelling and simulation of downstream and upstream production impacts and the optimisation of strategic mine plans to quantify changes in net present value due to different preconcentration strategies. This framework has been applied to evaluate preconcentration techniques at numerous metalliferous operations and can also be used to quantify changes in the environmental metrics for energy, water and steel consumption and emission, tailings and waste rock production. This paper collates the results of these Grade Engineering® studies to show the range and magnitude of economic and environmental impacts attributable to preconcentration. The studies have shown that rejection of uneconomic material prior to mineral processing activities can have a pronounced improvement in energy, water and comminution steel productivity, emission intensity and the profitability of metalliferous mining.

Nov 10, 2020

By T P. Medhurst

In many cases mine design is the most important driver of the profitability of a mining project, however to reach an æoptimumÆ mine plan many compromises have to be made. Some of the fundamental profit (and loss) drivers relate to stoping methods and stope design parameters. Inevitably trade-offs have to be made between the stability of underground openings, ground support costs and production efficiency. This paper looks at the role of geomechanics in the mine planning and design process. The concepts of æcontrollable lossesÆ and æuncontrollable lossesÆ are developed as a means of partitioning ground control costs. A stope design example is given which provides a method of examining mining costs, and includes a decision making element in order to quantify geotechnical impacts and select stope dimensions. The method also provides a general framework as a means of balancing ground control costs against maximising returns from an underground mining project.

Jan 1, 2000

By P Cherepanskiy, G Elphick, R Hus, C Perring

When an iron orebody nears its end of life, the extracted material can become increasingly problematic to handle. Higher moisture content occurs as larger portions of originally-below-water-table material is mined, which in some deposits is accompanied by further changes in physical and/or chemical properties present along the edges of the orebody. Plant delays related to problematic material have affected all of BHP’s mining hubs to various degrees. Following the recent successful work in Yandi, where the development of an index to quantify the handleability of channel iron ore deposits resulted in an increase in extracted volumes and an extension to the expected life-of-mine, the value of implementing similar indices for bedrock iron ore deposits has been recognised. A materials handling index has been developed by combining observed empirical relationships between material properties and processing plant performance. Indices for each deposit were further refined and optimised by implementing a back-testing strategy which facilitated an understanding of what weighting or scaling each of the contributing components should carry to yield the highest success rate of predicting actual delays at a given plant. Currently materials handling indices are deployed to all mine sites and are made available in block models as well as calculated for individual blasthole and production samples. Values in block models are obtained by predicting the required properties using machine learning models, whereas hyperspectral data is used to ‘measure’ some of those properties on a sample level. This paper discusses the work that has been undertaken to obtain materials handling indices, the testing that has been done to optimise them, and what processes have been developed to ensure the best metrics are being used in the different planning and scheduling horizons to optimise extraction.

Jun 22, 2022

By B Reynolds

The process design for green- or brown-fields metallurgical plants typically starts with two fundamental elements: the detailed mass and energy balance and the plant flow availability. The detailed mass and energy balance is generally developed using process flow-sheet simulation software and represents the steady-state operation of the plant at normal operating conditions. The plant flow availability, also known as a range of other industry-specific terms such as ‘flow availability’ and ‘operating factor’, describes the ratio of plant production to the steady-state mass balance. These elements are then used together as the basis for equipment selection and design.Plant flow availability takes into account a myriad of production loss factors including planned and breakdown maintenance, feed availability and composition changes, variability in operational performance and the interaction of batch and continuous unit operations. The combined impact of these loss factors are complex and as such plant flow availability is usually derived using a top-down approach such as comparison to an existing operation, a group of similar operations or to an anecdotal ‘industry leading’ benchmark. These top-down approaches are fraught with risk however, as they cannot factor in changes to equipment selection, flow-sheet or plant operating philosophy, and can result in over-expenditure of scarce capital or shortfalls in plant production.The use of dynamic simulation to provide a bottom-up alternative to quantifying the plant flow availability in metallurgical plant design has been growing rapidly in recent years. It provides a technique to quantify the combined impact of the loss factors described here and a tool to support process design and equipment selection by facilitating a range of sensitivity and what-if analyses. This paper presents a case study of how dynamic simulation has recently been used to support the

Aug 8, 2011

By G Gilchrist, S C. Dominy, T Jashashvili, R C. A Minnitt

The grouping and segregation error is one of Gy’s seven errors that cannot be measured in any qualitative manner because of its transient and changing characteristics each time the sample is handled mechanically. Attempts to calculate the mean and variance of the segregation error is considered by some as ‘an exercise in futility’ that would not help us achieve representative sampling. This research is aimed at understanding the process of segregation of dense, finely divided and dilute particulate materials supported in a clean quartz substrate during intense agitation. Several mixtures of fine-grained materials including steel, tungsten carbide and gold grains were used in these experiments. Four hundred grains of each of the minerals and metals at a top size of 2 mm were mixed with approximately 600 g of finely ground quartz material (95 per cent passing 2000 microns) in a 500 ml plastic jar with a sealable lid. The mineral–?metal mixtures were analysed in three steps using microfocus X-ray computed tomography. Step one consisted of rolling the containers on a flat surface in an attempt to concentrate the mineral and metal grains in the core of the supporting substrate; this is a base case that can be reconstructed after each session of analysis. The second step involved gentle and vigorous shaking of the mixtures in order to segregate the denser minerals and metals from the supporting quartz substrate. In some cases, a third step involved splitting the sample through a riffle splitter. Three-?dimensional images of the surface of each grain, its volume and its X-, Y- and Z-coordinates, before and after intense agitation of the container, were interpreted from the reconstruction of the tomographic X-ray data. The spatial analysis of grains using cell declustering and 3D variography provided a useful means of characterising the distribution of the grains in space and the extent to which they had become segregated during the process of agitation. Spatial analysis indicates that in general, grouping and continuity of grains is weakly developed. The modelled nugget effect remains high for most tests, indicating that grains of similar size did not group together strongly. Agitation through rolling provided the best continuity, although not consistently in the long axis of the plastic jar. The nugget effect was consistently highest, and the range of continuity shortest in samples that had been split, indicating that the grouping and continuity were reduced through splitting the sample. Initial results indicate that very little segregation of the minerals and metals occurs in the quartz substrate. This is somewhat counter-intuitive, but suggests that the effects of agitation on mixtures of dense minerals and metals in substrates of lower density do not lead to excessive segregation. Differences in behaviour between dense materials in response to agitation are evident. Grains of different composition and shape did not group and segregate in a predictable manner in response to the agitation methods. Initial results indicate that the degree to which a material groups and segregates relates more to the characteristics of the denser material itself, rather than the agitation method employed.CITATION:Minnitt, R C A, Jashashvili, T, Gilchrist, G and Dominy, S C, 2017. Quantifying segregation of minerals and metals in particulate materials using computed X-ray tomography and variography, in Proceedings Eighth World Conference on Sampling and Blending , pp 173–182 (The Australasian Institute of Mining and Metallurgy: Melbourne).

May 9, 2017

By J. F. Kvitfkovich, R. L. Bate

Coal production in the Central Appalachian region has a long history, and it remains a major US coal-producing region. The coal industry consensus is that the region is in a state of decline as evidenced by the recent lower regional output. Are Central Appalachian coal reserves adequate for the region to continue as a major supplier of low sulfur coal? To answer that question, this paper focuses on the Central Appalachian coal reserve base estimates and production trends. Central Appalachian (CAPP) reserve evaluations face the difficulty that there are no publicly available databases that provide a thorough analysis of remaining CAPP reserves. Based on best available Energy Information Administration (EIA) data, a coal reserve estimate of 17.6 billion tons is developed. This estimate appears high according to industry perception. Recent United States Geological Survey (USGS), and other state agency coal reserve estimation projects are evaluated as alternative approaches to the re-serve estimation problem. Using the conclusions from these studies, the CAPP reserve base is estimated at 7.1 billion tons. Another perspective on the CAPP reserve base is provided by reserve holdings of major CAPP operating companies reported at 5.2 billion tons. A conceptual mining cost analysis indicates substantial price increases will be necessary to offset this deterioration in the economic viability of the reserve base.

Jan 1, 2004

By J C. de Vries

When times are tough in the mineral industry û as they have been for some time û typical responses by mining companies are to cut costs and/ or increase production. The latter is seen to spread fixed costs, thereby also reducing unit costs per tonne mined. However, most mineral deposits respond to increased production rates by lowering ore grades, so the reduction in cost per tonne of ore does not necessarily result in a reduced cost per unit of metal produced. The authorsÆ experience is that this process often leads to a mine plan that is a long way from optimal. Producing to the point where marginal cost equals marginal revenue may work well in a manufacturing operation, but it is not necessarily the best strategy for a mining company with a depleting resource. Variations in tonnage and grade with depth, ore reserve optimism and a variety of other factors conspire to produce variations in production rates and grade that often result in suboptimal outcomes and potential mine failure. Added to this is the focus of industry analysts and senior corporate management on such measures as unit costs and ounces in reserves. This is perceived to have the perverse effect of driving the share price down when strategies are adopted that actually improve the value of the mining operation, and vice versa! Many mine failures can be prevented by a close examination of the tonnage grade curve and an understanding of how margins, net cash flows and resulting business risk change with cut-off grades and rates of production. A few relatively simple analyses early in the evaluation of a project can demonstrate the tradeoffs between the main decision parameters, leading to right-sizing of the operation. Once major commitments to major capital items have been made, and reserves have been publicly reported, optimisation of the operation becomes much more difficult than if it had been done earlier. Such investigations can also identify the upside potential and downside risks associated with factors outside the companyÆs control. Many strategies that may enhance value in the good times significantly increase the downside risk in the bad times. What is often called risk analysis typically looks at superficial issues, and does not evaluate the major factors leading to the potential for financial disaster. This paper illustrates some of these major risks, and demonstrates how they may be fully evaluated so that corporate decision makers can make fully informed decisions that take account of the real risks.

Jan 1, 2003

By C. Samson, R. S. Smith, S. W. Hefford

"Abstract - Time-domain electromagnetic systems are most sensitive to highly conductive targets during the transmitter on-time. Data collected during the on-time is highly influenced by the geometric relationship between the transmitter and the receiver. Unless corrections can be applied for these geometric variations, the ability to correctly detect and identify highly conductive targets can not be fully realized. Variables affecting the relative position between the transmitter and receiver include changes in the position of the receiver with respect to the transmitter, variations in transmitter attitude, and transmitter loop deformation. The level of accuracy in the determination of the relative geometry required to permit complete removal of the effects due to geometric variations is different for each of the variables and is dependent on the depth of the target. The most influential geometric variation involves changes in the relative position of the receiver with respect to the transmitter along the direction of flight; this variable, therefore, requires the highest degree of accuracy. The accuracy required for receiver motions along the vertical direction is roughly one order of magnitude less, and in the lateral direction, several orders of magnitude less. The objective of this paper is to relate the sensitivity of the response to transmitter-receiver geometry to the ability of an airborne, time-domain electromagnetic system to resolve a highly conductive vertical target. This is achieved by a detailed analysis of the effect of the individual x, y, and z distances between the transmitter and the receiver, the transmitter attitude (roll, pitch, and yaw), and transmitter deformation.Sommaire - Les systèmes électromagnétiques en domaine temporel sont particulièrement sensibles aux cibles à forte conductivité durant le temps d’excitation. Les données collectées durant l’émission du transmetteur sont fortement affectées par les relations géométriques entre le transmetteur et le récepteur. Si un facteur de correction n’est pas introduit pour tenir compte de ces variations géométriques, la capacité de ces systèmes à détecter et identifier correctement les cibles fortement conductrices ne peut pas être pleinement réalisée. Les facteurs affectant les positions relatives du transmetteur et du récepteur comprennent les changements de position du récepteur relativement au transmetteur, les changements d’altitude du transmetteur et la déformation de la boucle du transmetteur. Le degré de précision requis pour déterminer la configuration nécesaire pour compenser complètement l‘effet des changements géométriques est différent pour chacune des variables et dépend de la profondeur de la cible. Les changements géométriques qui ont le plus d’influence sont ceux qui font varier la position du récepteur relativement au transmetteur dans l’axe de la ligne de vol; c’est donc cette variable qu’il faut contrôler avec le plus de précision. La précision requise pour le suivi des mouvements du récepteur le long de l’axe vertical est moindre d’environ un ordre de grandeur, tandis que selon l’axe latéral elle est diminuée de plusieurs ordres de grandeur. Le but du présent article est d’établir comment la susceptibilité de la réponse à la géométrie transmetteur-récepteur affecte la capacité d’un système électromagnétique en domaine temporel aéroporté à reconnaître une cible verticale fortement conductrice. Cet objectif est atteint par l’analyse détaillée de l’effet individuel des distances x, y, et z entre le transmetteur et le récepteur, l’attitude du transmetteur (lacet, roulis, tangage) et la déformation du transmetteur."

Jan 1, 2006

By J Seppelt, G S. Lane, E Wang

Newcrest’s Cadia concentrator operated from 1998 to 2012 with a traditional SABC grinding circuit treating Cadia open pit ore. The Cadia comminution circuit was well characterised through surveys and data that are available in the public domain, and became a benchmark standard for the industry and practitioners modelling large SAG mill based circuits. In 2012, the HPGR-based crushing circuit was introduced in front of the SAG mill to increase throughput when treating the Cadia East ore that was derived from an underground block cave. This ore was expected to be more competent and have a coarser run-of-mine size distribution.Numerous previous papers have described the design and commissioning of the Cadia HPGR-based circuit.This paper describes the improvement in comminution energy consumption resulting from the introduction of the HPGR, including identifying the impact of process complexity and an increase in ancillary energy consumption for conveyors, screening, and crushing.CITATION:Lane, G S, Seppelt, J and Wang, E, 2018. Quantifying the energy efficiency transformation at Cadia due to HPGR crushing, in Proceedings 14th AusIMM Mill Operators' Conference 2018, pp 141–152 (The Australasian Institute of Mining and Metallurgy: Melbourne).

Aug 29, 2018