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By Mario A. Morin

The last few years have seen considerable consolidation of the mining software industry and a trend towards greater planning and production control system integration, particularly for surface mines. The mining industry is starting to realize the benefits of system integration and will continue to drive the evolutions of these systems. Several trends can now be observed. The trends include application and system integration, data portability, ?intelligent? systems for support of decision-making activities, mine process-control and automation. While many planning systems are moving in this direction, there is room for considerable improvements. This paper will discuss these trends, examine the current state-of-the-art in mine design software, and identify areas where improvements should be made and why.

May 1, 2004

By Cheryl L. Allen

The power required to operate a ventilation system can be 25% to 50% of the total energy requirements of a mine. In an effort to reduce energy consumption, initiatives are being introduced at Vale Inco to increase the efficiency of ventilation systems with the objective of decreasing energy usage. One energy conservation measure being introduced is the use of variable frequency drive (VFD) technology for fan motor control. Advancement in technology is making VFD applications more of a standard in industry. The benefits include improved operating performance and system control, reduction in current peak demand, and optimized power usage. This paper describes the application of VFDs for main and auxiliary mine fans; and associated potential energy savings.

May 1, 2009

Introduction Gold Mining is an Important Economic Activity in Canada n Total value added during 1990-99 was $15.5 bn n The gold price is an important factor in the value added process n The gold price affects gold mining output, profits, exploration expenditures, employment, etc. Some Factors that Affect the Gold Price n The value of the US Dollar affects the US Dollar price of gold: a weaker US$ correlates with a higher gold price n Supply affects the gold price: the higher the supply on the market each year, the lower the average gold price that year Central Bank Gold Sales n Yearly central bank gold sales add to supply, and affect the price of gold negatively n The negative impact on the price of gold reverberates through the Canadian gold mining industry n Despite the modest amounts, even Bank of Canada gold sales affect the Canadian gold mining industry

May 1, 2003

By Jorge Amaya

A critical aspect of long-term open-pit mine planning consists in computing a production schedule based upon a block sequencing strategy. Such a schedule should specify when and if blocks should be extracted in such a way as to maximize NPV, while satisfying wall-slope and production capacity constraints. It is well known that this problem can be modeled with integer programming (IP). However, integer programming is not used in practice because the size of typical block models makes such problems intractable to standard IP solvers. In this article we describe a scalable IP-based methodology for solving very large (millions of blocks) instances of this problem. We show that embedding standard IP technologies in a local-search based algorithm we are able to obtain near-optimal solutions to large problems in reasonable time. This methodology has been tested in several mine wide block models.

Oct 1, 2009

By Jorge Amaya

A critical aspect of long-term open-pit mine planning consists in computing a production schedule based upon a block sequencing strategy. Such a schedule should specify when and if blocks should be extracted in such a way as to maximize NPV, while satisfying wall-slope and production capacity constraints. It is well known that this problem can be modeled with integer programming (IP). However, integer programming is not used in practice because the size of typical block models makes such problems intractable to standard IP solvers. In this article we describe a scalable IP-based methodology for solving very large (millions of blocks) instances of this problem. We show that embedding standard IP technologies in a local-search based algorithm we are able to obtain near-optimal solutions to large problems in reasonable time. This methodology has been tested in several mine wide block models.

Oct 1, 2009

By Bish Chanda

In the minerals business, like any other commodity-based business, management faces the daily challenge of holding down costs while the real prices of products are continually falling on an inflation-adjusted basis. Since the marketplace sets the prices, often without any premium attached for product quality, being one of the lowest-cost producers is the most viable competitive strategy. Continuous improvement is the mantra that can make the difference in terms of long-term survival of a mining company. Yet, this message has not always been followed, especially during periods of prosperity ushered by high commodity prices. More often than not, the need for improvement is only triggered by a crisis. This may be caused by events such as the onset of a severe economic recession, a prolonged oversupply situation due to an optimistic expansion of capacity during the period of prosperity, or simply falling profits alerting management to bring costs under control. At that time, there would be a need to implement a new cost-saving program, bring in a consultant to find ways to reduce costs, or re-activate an old program that had been shelved for some time.

May 1, 2003

By Christopher W. N. Anderson

Induced hyperaccumulation of gold by plants was first reported in 1998 by researchers from Massey University in New Zealand who proposed the idea of mining gold using plants (phytomining). Since that time research has been conducted to understand the conditions under which plants can be made to take up economic amounts of the metal. One key focus has been on the geochemistry of gold-rich soils, leading to a diagnostic test that can predict how suitable a particular soil might be to gold phytomining. Field trials have been conducted at several locations around the world in collaboration with industry partners. A Decision Support System has been developed to assist in the design and management of phytomining operations, and economic modeling has been carried out to set targets levels for phytomining technology. Novel studies are now examining the form of gold in plants. Research suggests that plants may store gold as discrete metallic nanoparticles in leaf and stem tissues, an observation that may lead to new ways to recover the metal from harvested biomass.

Oct 1, 2003

By H. Polkowska-Motrenko

Analytical methods for the determination of uranium and other precious elements in ores, industrial wastes and by-products have been developed. The analytical techniques employed are NAA and ICP-MS. Two procedures of digestion were applied: microwave acid digestion and alkali fusion. Accuracy was checked by using CRMs. Results of analysis of the same samples by the elaborated methods have been presented and compared. The methods will be used for estimating the capacity of uranium production for the Polish nuclear power programme.

Aug 1, 2010

By Michael Samis

NOFLEX valuation results ? CF deviations and net CF risk discount factors ??Cash flow deviations indicate average cash flow variability. ??Net cash flow riskdiscount factors (NCFRDFs) indicate the size of the risk adjustment applied to a cash flow. NCFRDFs profile should change with variations in cash flow uncertainty since the risk adjustments applied to the project cash flow reflect investor sensitivity to uncertainty.?DCF and RO will often produce different NCFRDFs for the same project since they use different methods of risk-adjustment.

May 1, 2006

By Larry Urbanoski

"This paper describes the application of a radioisotopic energy dispersive X-ray aY1alyser to complete on-stream analysis in a base metal concentrator.The major components of the system are outlined and some description of the application, operating experiences and benefits are provided.IntroductionThe ma1n intent of this paper is to describe the on-stream analysis system in operation at the Geco concentrator. X-ray analysis systems installed in Canadian concentrators to-date may be broadly classified as wavelength dispersive analysers whereas the installation described herein is an energy dispersive x-ray analysis system. Energy dispersive x-ray analysis techniques may utilize radioactive sources to provide primary x-rays for excitation of elements and separate the secondary x-rays on the basis of energy levels. In contrast wavelength dispersive analysers apply high voltage x-ray tubes to provide primary x-rays and utilize crystals to disperse and thereby separate x-rays generated by bombardment of the sample."

Jan 1, 1978

By J. A. Hurd

Towards the goal of a better understanding of the structure-proton conductivity relationship in PEM materials, this project concerns the design of ordered polymeric solids containing well-defined sulfonate aggregates. The approach employed involves the templation of sulfonated monomers using core principles of crystal engineering. In addition to sulfonate groups, the monomeric units contain crosslinkable functionalities to enable formation of a covalently linked network. The templation strongly directs the construction of well-defined sulfonate clusters and aggregates. Structural, sorption and conductivity data for the networks will be shown.

Jan 1, 2005

By Y. Qi

A cell-level nonlinear dynamic model of solid oxide fuel cell (SOFC) based on physical diffusion principles is built in this note. It demonstrates that reactant diffusion processes from gas flow bulks to triple phase boundaries (tpbs) play an important role in the dynamic behaviors of SOFC. The simulation shows that under certain condition, the effect of the double layer capacitance may be neglected. The phenomenon of slow rise of voltage in current interrupt experiment may be explained by the dynamic behaviors of partial pressures in the vicinity immediately above tpbs.

Jan 1, 2005

By Jan Nemcik

Among other products steel mesh has been used successfully for many years to support strata and minimise loose material from falling into the mine opening. Installation of steel mesh has proven to be difficult to automate and many other products, such as Thin Spray-on Liners (TSL), have been proposed as a replacement. Ideally, the mechanical properties of these products should be superior to those of the steel mesh, however, most TSL trialled in mines to date have been weak and in addition have had slow cure times, as a result none of these materials can seriously compete with steel mesh. Now a new polymer product that cures in seconds and forms a stiff strata binder that surpasses the properties of steel mesh is under development at the University of Wollongong. To enable selection of a suitable polymer material for roadway skin reinforcement several numerical models were constructed to investigate the role of interface roughness and the influence of polymer stiffness on load transfer along the rock-polymer interface. Laboratory tests indicate that the shear adhesion of the rock-polymer interface can be substantial while the tensile adhesion can be much lower. The models indicate that the natural stone roughness and surface waviness plays a major role in shear adhesion while the elastic properties of polymer liner can significantly influence the polymer ability to resist fracture opening.

Oct 1, 2009

By T. A. Postolski, A. J. Sinclair

"Abstract- Two examples are used to describe how geological features impact on the development of semi-variogram models to be used for geostatistical resource/reserve estimation of porphyry-type deposits. In the Main zone of the Huckleberry porphyry copper deposit, mineralization is concentrated in fracture zones localized in volcanic rocks, along the eastern and southern margins of a granitic stock. Mineralized volcanic rocks can be subdivided into three separate domains, each with its own preferred direction of mineralization that is reflected in contoured Cu diagrams and semivariograms.The East zone at Huckleberry deposit, spatially distinct from the Main zone, is controlled by a fracture zone elongate roughly east-westerly and bounded on the south by a major fault (easterly striking and steeply dipping) across which there is a dramatic drop in grades. The eastern part of the East zone appears to be coaxial with a large intrusive body; the western part contains a small, elongate dike-like intrusion. Contoured Cu values for many levels suggest that the principal direction of geological elongation of the east and west domains of the East zone differs significantly. Independently derived semi-variogram models for each domain are different and reflect this difference in trend.In both Main and East zones of the Huckleberry deposit, block estimates by ordinary kriging are significantly different using a domain-specific semi-variogram model than using a deposit-general semi-variogram model. The domain-specific estimates are deemed better because they are based on local controls of mineralization and have less conditional bias than those generated by the depositgeneral semi-variogram model."

Jan 1, 1998

Adaptive Processing as proposed in geometallurgy has to rely on spatially interpolated information on geometallurgical parameters like phase composition, size distributions of particles of different phases, grain shape parameters, and portions of value elements in different grains. Using the geostatistically predicted values for adaptive processing, e.g. for the selection of milling diameters, thresholds in physical separation, or choices on using an extra pre-separation step, is typically not optimal. Mathematically this effect is introduced by two forms of nonlinearities: 1) The nonlinear scales of compositions, distributions, and shapes have special properties with respect to geostatistics. Classical geostatistics creates some artefacts for these nonlinear scales. On the other hand, modern geostatistical procedures adapted to these scales do not provide unbiased results with respect to linear transformations of the data (e.g. biased block estimates). 2) Neither economic nor ecological effects (e.g. monetary gain) of processing decisions are linear in the interpolated geometallurgical parameters. These nonlinear transforms are not unbiasedly estimated by the likewise transformed unbiased geostatistical predictions of the geometallurgical parameters. Furthermore, we need to optimize the conditional expectation of the gain, rather than obtain an unbiased estimate. Standard geostatistics as such does not provide the "right sort" of estimates for adaptive processing. A nonlinear kriging procedure is needed to approximate the nonlinearities mentioned before. We propose to solve these problems simultaneously using a nonlinear geostatistical technique for predicting the target function (the monetary gain), rather than to predict the geometallurgical parameters and compute the gain from them. The optimization can then be performed directly on this estimated function. It can be shown that this optimization performed on the conditional expectations, not on unbiased predictions, would yield the best possible processing choice. We propose a procedure choosing the processing parameters on an approximation of the conditional expectation. The difficulties with the classical approach and the effectiveness of this new approach are illustrated by a simplified simulation example with a single processing parameter and a simple dependence on the microstructure.

Aug 1, 2013

"The Dome Mine, located in South Porcupine Ont. has been in operation since 1910 and is owned and operated by Placer Dome Inc. The current milling facilities were constructed in two phases with the first being commissioned in 1982. It consists of a grinding, gravity separation, thickening, and leaching circuits. The second phase was commissioned in 1988 with the addition of the CIP, stripping, electrowinning, and carbon regeneration circuits.It is now common practice in the gold processing community to add liquid oxygen to leach circuits to increase both recovery and kinetics. Along with these benefits the metallurgical group at the Dome realized the potential to replace compressed air with liquid oxygen as a source of oxygen for the dissolution of gold. A plant trial of liquid oxygen was undertaken during the fall of 1991. The results of this first test were favourable enough to warrant further investigation, and a second plant trial was conducted in December 1991.The data generated as a result of each trial revealed that oxygen could be economically substituted for compressed air as a source of dissolved 02. The energy savings in required horsepower enabled a rapid payback period. Thus the project was approved in the spring of 1992 and l should be operational during the final quarter of 1992. INTRODUCTIONIn a continuing effort to reduce operating costs and improve recovery at the Dome mill it was decided to investigate the feasibility of adding liquid oxygen (02) to the leach circuit. It is now common practice in the gold processing community to add 02 to the leaching process to increase both kinetics and recovery. It was anticipated that an increase in kinetics would allow us to eliminate one or more leach tanks while maintaining acceptable recoveries. The metallurgical group felt that along with these benefits, the potential was also there to reduce power consumption through the reduction in the processing of compressed air which is quite costly (12 cents/1000 cubic feet per minute in 1991)."

Jan 1, 1993

By Leibniz University, D. Zapf

"The demand for gas storage operations with high withdrawal rates and operation modes different to a seasonal storage regime requires a more detailed rock mechanical consideration of thermal induced stresses in the vicinity of the caverns. This means that the change of gas temperatures during operation and the consequences of these temperature changes on the stressing of the salt rock mass must be taken into account in the rock mechanical dimensioning. Within the rock mechanical calculations a loading history, i.e. a pressure versus time dependency, has to be defined. As rock salt has a time dependent material behavior stress redistributions in the rock salt mass take place even under constant internal pressure conditions. Therefore not only withdrawal and filling periods but also the duration of phases with nearly constant internal pressure is significant for the resulting state variables. Within the paper the differences and consequences for the rock mechanical recommendations are discussed. As a result it can be concluded that recommendations with respect to minimum operation pressure as well as for maximum withdrawal rates can be answered only in connection with the respective time intervals."

Jan 1, 2015

By Hang Zhao, Xinping Li, Pingan Wu, Yi Luo

The deep-buried rock surrounding the Jinping II Hydro-power Station was taken as the engineering background. Using model specimens of classified rock materials to simulate fractured rock mass under high in-situ stress conditions, the test about acoustic propagation law on single fracture model of specimen under different pressures and different angles were carried out. The variation of p-wave velocity in fractured rock mass and axial stress-strain relationship in the whole test procedure was also studied. Based on damage mechanics principle and the acoustic wave propagation in cracked rock mass, comparative study on damage constitutive relation of fractured rock mass under high in-situ stress in consideration of equivalent strain and equivalent energy was performed. As the results showed, with the change of axial stress level under constant confining pressure, the change in wave velocity can be divided into three stages: slow increase (small variation in amplitude), rapid reduce (large variation in amplitude ) and accelerate reduction. When the confining pressure is constant, the maximum p-wave velocity and the peak strength of specimens increases with the decrease of the crack angle. When the crack angle is constant, the maximum p-wave velocity and the peak strength of specimens increases with the increase of confining pressure.It is identified that the theoretical calculation results of constitutive relation about elasto-plastic damage model containing variable wave velocity in the fractured rock mass is consistent with the model test results.Therefore,the constitutive relation can provide reasonable suggestions for engineering practice.

Jan 1, 2015

By Weimin Fu

Chondrite-normalized rare earth elements (REEs) profiles and high field strength elements (HFSEs) in rocks and minerals represent important tracers of geological processes. Of these the birdwing-shaped profile with negatively-sloped light REE ((La/Sm)N >1), positively-sloped heavy REE ((Tb/Yb)N <1), and strong negative Eu anomalies is commonly associated with large-scale hydrothermal systems or granitic intrusions. In a different way, severe deviation of Nb/Ta, Hf/Sm ratios from those of chondrite may also indicate hydrothermal signatures in the rocks involved as these ratios are generally stable and chondritic in normal magmatism as a result of their nearly identical ionic radii and charge. In this study, we present a typical setting where birdwing-shaped REE profiles together with Nb/Ta, Hf/Sm ratios unusually higher than those of chondrite, are systematically developed in a series of garnetite, quartzofeldspathic gneiss, Fe- or Mg-rich aluminous gneiss, and sulfides and magnetite. These units and associated Cu-Au mineralization form a VHMS-style hydrothermal system in the granulite-facies 1.4 Ga -1.35 Ga volcano-plutonic, arc-related Bondy gneiss complex (BGC), western Grenville Province, Canada. Outside the recognized hydrothermal system of the BGC, such REE profiles are not observed. Instead the surrounding felsic and mafic gneisses display primary trace element characteristics of island-arc magmas, suggesting that granulitefacies metamorphism did not modify significantly the trace element signatures of the protoliths. Although magmatic fractionation of accessory minerals can produce birdwing-shaped profiles, it cannot explain the extreme fractionation of isovalent trace elements (Nb-Ta) and the high Zr content of the hydrothermal rocks. Neither is it compatible with the lack of significant Nd depletion that would normally incur during this process. Following our study, we demonstrate that F-rich fluid and mineral phases enriched in LREEs and HREEs respectively must have been involved in the main hydrothermal alteration and REE fractionation process in the BGC. Preferential removal of REEs from the interstitial glass of the volcanic protoliths together with dissolution of plagioclase and subsequent external influx of HREEs and HFSEs can produce birdwing-shaped REE profiles. In turn, such profiles and/or unusual Nb/Ta, Hf/Sm ratios can be used as a sensitive marker of hydrothermally altered rocks in targeting mineral exploration.

May 1, 2003

By M. Y. Williams

Introduction During the economic investigation of Pacific Great Eastern Railway subsidy lands, the P.G.E. Survey of Resources made a geological and mineral survey of a large part of the valley of the Peace river as included in the Province of British Columbia. The immediate valley of the Peace river was surveyed from the mountains to the Alberta boundary; the valley of the Pine river was surveyed throughout; and the Dominion block, 70 miles square and lying astride the Peace river, westward from the Alberta boundary, was very carefully surveyed. The writer was in general charge of the field work, and spent half the field season of 1929 and the field season of 1930 in the region . J. B. Bocock, however, did the major part of the work, spending two seasons, 1929 and 1930, in the area. General Conclusions The rock formations within the area discussed are all sedimentary and range in age from pre-Cambrian to recent. As might be expected, the minerals are in the main non-metallic, coal being by far the most important. Favourable conditions exist for natural gas occurrence, and suitable structures for petroleum concentration occur, although the high carbon ratio of the coals sheds considerable doubt upon the actual occurrence of oil in the area. Materials of minor interest are ochre, calcareous tufa, marl, limonite, gravel, and building stone.

Jan 1, 1934