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By Stephen G. Downs

PCF?, or Penetrating Cone Fracture, is a propellant-based technique for rock excavation, which has significant potential for the mechanization of narrow-vein mining. The technique is currently being developed for use in the narrow-vein flat-dipping gold and platinum deposits in South Africa in conjunction with major mining companies. The technique is also applicable to steeply dipping vein deposits, such as those found in North America, Australia and elsewhere. The implementation of PCF? in South Africa to date is reviewed and plans for the introduction of PCF? excavation in other areas are highlighted.

Oct 1, 2001

By Paul J. O'brien, George N. Neary

"The base metal mine at Buchans, Newfoundland, has been producing since 1928. For many years, mill tailings were disposed of by dumping into a nearby natural watercourse via which they were transported to Red Indian Lake and deposited. In 1965, environmental concerns prompted the establishment of settling ponds near the mine site. Effluents fed to these ponds included slimes washed from mine backfill sand and waste water pumped from underground as well as mill tailings. Dusting around the perimeter of the ponds was first observed around 1970and within a couple ofyears reached serious proportions. A program to alleviate the condition by developing a vegetative cover over the tailings was commenced in 1974. The work was successfully carried out and demonstrated that the large area of waste could sustain a permanent cover of grasses.This paper outlines the experimental work done at Buchans as well as the procedures followed and the problems encountered in carrying out full-scale revegetation."

Jan 1, 1981

By C. O. Aksoy, H. Kose, K. Heasley, E. Yalçin

"In Turkey, the growing demand for lignite has resulted in increased lignite production and an emphasis on improving underground recovery. This has resulted in a gradual increase in the application of the retreat longwall mining method and also in the extraction of the safety pillars protecting permanent underground structures (drifts, shafts) in mines prior to their abandonment.Extracting these safety pillars presents a special hazard to mine employees and the stability of the mine. Often subjected to high stresses, the behaviour of these pillars is not always predictable. Special care must be taken to ensure that infrastructure does not collapse prematurely, and that working conditions remain safe. Otherwise the extraction must be halted, and the remaining coal lost.This investigation reports on a study of the stability of safety pillars during the final extraction phase of the Hustas mine in Soma, Turkey.” The model construction was based on mine plans, and material properties were derived from physical properties testing. Observed subsidence effects from other mining events were used to calibrate the overburden lamination thickness.The model results compared well with surface physical disturbance occurring as a result of mining, as well as with conventional longwall stress redistribution theory and underground observations. The study has shown that properly calibrated models can be useful in assessing mine safety during remnant pillar extraction. The LAMODEL results demonstrate the convenience of this easy to use software."

Jan 1, 2004

By John G. Henning

The Porcupine Joint Venture operates the Dome Mine in South Porcupine, Ontario. Dome underground began production in 1910. It is the longest continuous operating gold mine in Canada, producing in excess of 15 M ounces. More than 900 underground stopes have been mined and hundreds of miles of drifts, sublevels and raises developed. Underground mining methods included shrinkage, cut and fill and longhole. Not all stopes were backfilled upon completion, particularly the longhole stopes. The Dome open pit was designed above the underground mine workings such that, as the pit is excavated, it intersects underground drifts and stopes. Potential operational problems associated with the interactions between the stopes and the pit walls may occur, necessitating pit wall redesign, ground support installation and operational rescheduling. Each intersection of the pit with the underground mine workings is closely evaluated to maintain a safe working environment and wall stability. This paper discussed how risks to pit wall stability are assessed, mitigated and monitored.

May 1, 2004

By Phil Thwaites

"The mining industry uses many types of mineral and metallurgical plants to produce saleable product from ore mined. Plant design history has left current operations with a mixture of manual operation and various forms of automated process controls. Consequently, we typically see high variability in the continuous operations together with a shortfall in the attainment of full capacity, or higher utilization of consumables.At a level of best practice, “Operational Performance Excellence” focuses on process control, using automation and control systems to deliver process optimization. This more sophisticated delivery is a great deal more difficult than the first stage of equipment selection / installation. It includes the appropriate selection of the right instrumentation, control system, key process knowledge, individuals with a solid control engineering background/experience, and the essential backing/ support of the operations management team together leading to higher value delivery. Robust solutions can be realized, considerably minimizing process variation, thus leading to process optimization. This approach results in an easier, efficient and safer process while providing considerable returns for the plant owners.How variable are your processes, and do you maintain optimized process performance with dedicated resources, modern instrumentation, ‘best practice’ control systems and performance monitoring tools? In this lecture, these questions and their possible answers are discussed.357"

Jan 1, 2013

By John Hoffert, Darren Colwell, Greg Tucker, Jeremy Kinch, Greg Rasmussen

"The Kemess Mine, a major producer of gold and copper, is located in north-central British Columbia. Kemess was brought into production in May 1998 by Royal Oak Mines. On February 11, 2000 Northgate Exploration Limited acquired Kemess Mine from receivership. Since acquisition in 2000 Kemess has seen many accomplishments, including the reduction of costs by 40%.One of the largest site capital costs was the construction of the tailings storage facility dam, which when finished will be one of the largest earth filled dam structures of its type. The existing construction design by AMEC called for a kilometer wide rock dam to be built from the 1350 M elevation to the 1504 M elevation at a 5.5:1 slope by hauling over 30 million tonnes of non-acid generating waste rock 7-kilometers from the open pit to the tailings dam, which was highly expensive.Kemess realized an opportunity for cost reduction was possible if the dam could be built from suitable quality tailings sand; however the sand did not meet the neutralizing potential ratio specifications. It was determined that cycloning combined with flotation to reduce pyrite concentration in the sand would produce a non-acid generating product for dam construction. The sand plant design challenges were to remove the sulphides from the tailings to obtain an NPR greater than 2:1 and provide a consistent sand product for the construction with a fines content of less than 15% passing 200 mesh. After a 2-year testing design and construction period, the sand plant was successfully started at the end 2002 resulting in higher than expected sand quality and production rates.This paper describes the plant design phase, commissioning, and operation of the tailings sand plant for construction of the tailing storage facility dam to enable us to meet all the engineering and regulatory requirements. The many challenges faced were successfully met using several innovative designs. The operational, economic, and environmental benefits are detailed."

Jan 1, 2004

By J. A. Stewart

"A common problem in the mining industry involves the overloading of established conveyor systems. This overloading can have a number of causes, such as new production technology or a changing market condition which increases demand. An overloaded system usually spells disaster and leads to clean-up problems, equipment failures and lost production. The Cape Breton Development Corporation's Lingan Mine had a serious overloading situation on its underground coal clearance system, and equipment was being damaged and production was being lost. It was rectified, in part, by increasing the coal clearance capacity through the use of booster conveyors. This paper discusses the problems which led to this situation, the booster concept and the installation of the first unit at the Lingan Mine.IntroductionThe Lingan Mine is a submarine coal mining operation with an annual production of 1.5 million tonnes from three advancing longwalls. Coal is conveyed 3400m up a 13% slope to the surface. Designed and installed in the early 1970s, the system's 820-tonne/hour design initially proved adequate; however, by the late 1970sthe system was handling surge loads of 1640 tonnes per hour due to the introduction of new face equipment.The coal clearance system consisted of three 485-Kw, two 210-Kw and one 105-Kw conveyors. Each conveyor was designed for 820 tonnes per hour using 1050-mm, Type 10 belt with a 35-degree troughing profile.There were many effects of the overloading on the system:• Loading beyond the physical capacity of the belt resulted in spillage along the conveyor, which increased operational and maintenance costs.• Overloading of the drive components resulted in premature equipment failures.• Spillage at the drive pulley often resulted in damage to the belt and pulley lagging and, under extreme conditions, the conveyor would require partial unloading before it would operate. This was a particular problem under wet conditions because the 485-Kw conveyor drives were fitted with single-drive drums."

Jan 1, 1982

By Jean Cayouette

"In 1995, Louvicourt Mine started one of the first paste backfill operations in Canada. From 500,000 tonnes in 1995, the annual paste backfill tonnage produced reached 800,000 tonnes in 1999. The maximum throughput of the surface plant (including binders) is 3,50Ot/d with a final density of 75 to 76% solids which gives a slump of 15 to 17cm. Following the start-up of the paste backfill plant, the backfill strength performance levels were well below the pilot plant’s predictions. The introduction of ferrous slag, laboratory tests on various binder ratios with or without additives, and the desliming of the tailings enabled us to optimize the mix and operation costs. Primary and secondary stopes are filled respectively with a paste containing 4.5% and 2% binders consisting of a mixture of 20% cement and 80% ferrous slag. In certain stopes, the binder ratio may vary from 2 to 7%, but always in a ratio of 80/20. Six years after start-up, or 4.5mt of paste backfill later, this paper discusses the present operation and the major changes that have occurred over the years to optimize both the operation and the paste fill quality.INTRODUCTIONLouvicourt Mine is operated by Aur Resources Inc. which owns 30% of the shares. Its partners are Novicourt Inc. (45%, subsidiary of Noranda Inc.) and Teck Corporation (25%). The mine is located in the north-west part of Quebec, about 600 km north of Montreal and about 25 km east of Val d’Or. The mine commenced commercial production in July 1994."

Jan 1, 2002

A series of fault slip seismic events have occurred at Garson mine. The events have occurred during development advancement exposing faults, after the extraction of single stopes due to mining induced stress change, and due to time effects after delays of many days during which no mining had been conducted. This paper discusses the study completed consisting of a global or holistic approach aimed at mitigating some of the risks associated with the structurally controlled rockbursts at Garson. Background Garson mine is located in the south east area of the Sudbury Basin (Ontario, Canada). Mining occurs in two main ore bodies (the #1 Shear and the #4 Shear) which are copper-nickel-sulphide and occur within shear zones that (as well as the ore bodies) strike approximately east-west and dip steeply south. From the north (footwall), lithologies progress (Figure 1a) from norite (NR), to greenstone (GS), and finally to meta-sediment (MTSD). A generally WNW-ESE striking, bifurcated sub-vertical dyke of olivine diabase (OLDI) cuts the series. The current active mining block at Garson is between 4700L and 5100L (levels denote depth in feet below surface).

May 1, 2009

By Marc C. Bétournay

Hydrogen fuelcells are a known technology, having been applied to stationary (e.g equipment, buildings, power plants) and vehicle applications (e.g transit buses, space shuttles). There is currently a growing need to provide alternate power systems to diesel fuel for underground mining vehicles to improve underground air quality and reduce production costs and green house gas emissions. To date, however, fuelcells have not been exposed to underground mine air and physical conditions. A testing program was carried out to provide information on the vulnerabilities of fuelcells as part of a number of proof-of-concept projects to apply hydrogen power to underground mining vehicles. The fuelcell type of choice for the industry, the Proton Exchange Membrane, would function at the range of temperatures encountered in underground and surface operations, and use hydrogen that is stored under low pressure and risk. A small fuelcell stack was tested in a cooperative project between CANMET, the Fuelcell Propulsion Institute, INCO, the Ontario Ministry of Labour, Sandia National laboratories and H-Power. This article will review the tests carried out to measure the effects from high humidity, mineral dust, diesel emission gasses and diesel particulate matter as well as from shock and vibration provided to the unit in underground conditions, at INCO?s 175 Orebody minesite and INCO?s Stobie Mine. The test results provided will show that the unit was not affected by the underground conditions: physically and electrically the unit performed without any reduction in operation or adverse effects imposed.

May 1, 2003

By H. A. Steane

"This presentation will cover some crushing and grinding considerations in plant design and operation. There is nothing basically new in the subject matter presented here; however, the viewpoint and interpretation may be novel and some of it controversial.The presentation is based on experience gained in the metallurgical design of plants for Placer Development Limited from 1960 to the present. The plants are listed on SLIDE No. 1.These plants have conventional crushing, followed by rod mill and ball mill grinding. I would like to think that autogenous grinding plants are the answer for eliminating secondary crushing plants and reducing the capital and operating costs; however, the autogenous plants seem to have some problems of their own and I have had no experience with them.Fineness of Grinding RequiredFirst let us consider the fineness of grinding required.The fineness of grind will affect the recovery obtained, and the relationship must be determined. If the grinding is too coarse, some of the valuable mineral, either free or locked in middling grains, will not be floated. However, as grinding is probably the greatest single operating cost, we do not want to grind any finer than is justified economically.Finer grinding should not be carried beyond the point where the net smelter return for the increment saved becomes less than the added operating cost. Even this fineness will be beyond the economic limit because of the additional capital cost for the equipment needed to achieve it. These factors will be discussed in more detail later.The Bond work index is the commonest method of expressing a measure of the effort that has to be expended in grinding. It is the kilowatt-hours required to reduce a ton of rock from an infinite size to 80% passing 100 microns. The formula allows a calculation to be made for other size ranges."

Jan 1, 1976

By Eduardo Nunez, Asim Tuzun, Dan Graffi, Glenn MacPherson

"In preparation for the milling of a new nickel and copper mine ore, Nickel Rim South, Xstrata’s Strathcona Mill is undertaking numerous process improvement projects. Within the grinding circuit, several projects are under development and an automated grinding control strategy, consistent with the operating objectives, was identified as a key requirement. The grinding strategy is to maximize the throughput (quantitative objective) while maintaining the cyclone overflow within specifications (qualitative objective).This paper describes the implementation of a robust grinding control strategy using the existing control system. The implemented controls maintain the cyclone overflow density at the desired target, while continually optimising the rod mill feed rate to allow maximum throughput. This approach has the added benefit of improving the stability of the rougher flotation circuit down stream of the grinding and improving energy efficiency of the rod and primary ball mills. This paper discusses the comparison of the before and after the implementation of results.INTRODUCTIONThe grinding process is a size reduction operation used in the mining industry to liberate the valuable minerals from the gangue. Grinding is one of the most important and expensive processes in a concentrator (Xi-song, 2007; Pomerleau 2000; Najim 1995), often accounting for around half of the total operating costs in base metal concentrators (Wills, 1990), which has led to a focus on development and implementation of control and optimisation strategies. The grinding process prepares the ore for the subsequent concentration step, which for sulphide base metal operations, is predominantly flotation. The performance of the concentration (flotation) is very much determined by the feed characteristics of the slurry coming from grinding. The valuable minerals recovery process in flotation is very much influenced by the grinding process and the liberation of the desired minerals from the gangue minerals (McIvor, 1991).The true objective of grinding is to obtain a proper liberation of the minerals as defined by a particle size distribution referenced typically by d80 (80% passing size of product). Besides achieving the desired mineral d80 size, it is clearly desirable to produce as narrow a size distribution as possible to squeeze the maximum amount of the mineral value into the highest recovery region (McIvor, 1991). This is an important criterion for the mill in economically optimizing the grade and recovery for the concentrate product. It is important not to over or under grind, while keeping the specific comminution energy as low as possible (Nunez, 2005) to achieve the target liberation. In other words, maintain an optimal throughput depending on the ore conditions to the capacity of the grinding mills, while providing the flotation process with a constant and narrow size distribution, at a cut size selected to meet the metallurgical requirements (Bascur, 1991)."

Jan 1, 2009

By D. Hatfield

"Flotation plants typically aim to maximise recovery at or above a target grade. As the ore from the mine varies, operators increase or decrease the mass pull in different flotation banks by adjusting air and level set points in order to achieve target concentrate grade. A methodology has been developed to maximise overall recovery at target grade by determining the optimal mass pull for each bank. However, the approach of targeting equal grade for each ore type in the deposit leads to sub-optimal overall recovery. This is because some ore types sacrifice a large amount of recovery to reach target grade while others easily achieve target grade and can be processed at higher than target grade for little or no loss in recovery. Processing different ore types at different grades and blending the concentrates therefore gives a higher overall recovery.This paper presents a case study where an 80 year production forecast was made for a large Chilean copper concentrator in feasibility stage. A circuit model was created using SGS’s Integrated Geometallurgical Simulator (IGS) for the different ore types to be processed. The model was calibrated from standard rougher flotation tests (MFT), cleaner tests and from the results of plant surveys of similar operations. The pull rates for each bank in the circuit were determined to achieve an optimal graderecovery curve for each ore type. These curves were combined at different concentrate grades for each ore type to obtain the mathematically optimal overall recovery at target grade. The paper shows a methodology for obtaining an optimal combination of operating conditions for each ore type to maximise overall recovery at a set combined concentrate grade."

Jan 1, 2013

By P. Desclaux, A. Gosselin

"In 1999, PFC measurements were carried out at Alcan smelters as part of a large measurement campaign led by the Canadian Aluminium Association. Side worked prebake (SWPB) and horizontal stud Söderberg (HSS) plants in Arvida were the selected sites. CF4 and C2F6 emissions were measured continuously in the exhaust duct and at the roof vents for a week. In parallel, voltages from four designated cells were recorded at a high scan rate. Results were analyzed and correlations between voltage, anode effect duration and PFC emissions were tested. Some fundamental anode effect mechanisms were proposed and validated with the observations. IntroductionFollowing the international agreement reached within the scope of the Kyoto protocol, voluntary partnerships have been established in many countries especially for the aluminum industry. It is well known that the PFCs that are periodically emitted during aluminum production are the major source of fluorocarbon emissions. The latter are part of the greenhouse gases. In the fall of 1999, Alcan announced that it will adopt, promote and regularly renew a long-term greenhouse gas management commitment at all of its facilities within the framework of the so-called TARGET program that was implemented during 2001. The program is intended to produce on-going reductions, which will be reported publicly on an annual basis.Improvements in the understanding of the mechanisms leading to PFC emissions will contribute to targeting the most appropriate reduction actions. PFC measurement campaigns have been driven toward this end. The first measurement campaign was conducted in 1993 in order to get a picture of the emissions and a base line. The last measurement campaign was conducted in 1999 and its main objective was to compare current emissions with those measured in 1993 and to confirm the accuracy of the predictive equations for the calculation of PFC emissions. This campaign has been conducted by the Canadian Aluminium Association and measurements were made in plants using different technologies. Results of this campaign have already been reported by Bouchard et al. (2001)."

Jan 1, 2002

By J. Sliwinski, J. Oliveira

"The application of geometallurgy and corresponding sample selection can take on several formats within industry. Current practice can range from a strictly geostatistical approach to one in which geological and metallurgical parameters are used in combination to create a representative sample selection strategy. The stage of a project and the level of information available at the time of sampling influences the methodology used to create a representative sample.A geometallurgical study of Carpathian Gold’s Rovina Valley Project in Romania is used to demonstrate a sample selection strategy that integrates geological, mineralogical and metallurgical data to maximize the relevance of the geometallurgical unit definitions. This approach, practiced by Xstrata Process Support for its’ clients, ensures that the results of the metallurgical program can be interpreted in the context of these units.INTRODUCTIONGeometallurgy is a cross disciplinary approach in which metallurgical performance of an ore is linked to intrinsic geological and mineralogical characteristics. The objective of a geometallurgical study is to characterize the range of metallurgical performance of an orebody. This allows the geoscientist or metallurgist to create a robust flowsheet able to treat the full range in variability and to develop production strategies to maximize financial performance. The standard approach is to individually sample and test a series of ore types or geometallurgical units. Several different approaches are used in industry to define what constitutes geometallurgical units and how to sample them.One current methodology is the use of multivariate statistics. Geochemical data along with available geological data are used to define multiple variability domains (Williams, 2004; Walters, 2009). There are risks associated with this methodology since the extent of the data set itself may not support a purely statistical approach at the time that metallurgical units need to be defined. The assay suite collected by exploration programs is often limited to pay metals while metallurgical performance is often affected by ore gangue components. Furthermore, in many cases metallurgical scoping and pre-feasibility studies take place prior to the availability of extensive geochemical data sets. Purely statistical methods can produce multiple populations which require extensive sampling, testing and validation prior to consolidation into a reasonable number of composites for metallurgical testing. Methodologies are therefore required that allow representative sampling and testing of consolidated geometallurgical composites to occur at various phases throughout the development of a mining project."

Jan 1, 2013

By A. Takala, B Nielson, J. Schunicht

"Pre-concentration in minerals processing presents clear advantages in energy efficiency, water efficiency, reduction of consumables and minimization of capital and operating costs. Outotec’s sorting solutions are powered by Tomra Sorting in order to achieve pre-concentration of concentrator feed in a variety of mineral processing applications. Sensor based sorting combines advanced sensors with rapid computational evaluation and mechanical separation of valuable material from waste and/or gangue. Modern sensor based sorting machines typically use fine air jets to propel individual rocks, thus optimizing recovery and minimizing “mis-sorting”.Gold is generally present in such low concentrations that sensors suitable for ore sorting cannot directly detect it. Therefore, in order to sort gold ore, properties of associated host rock are used. Free and sulphidic gold is often hosted on the quartz-host rock contact zone. Laser scattering effect can be used to detect the surfaces of quartz and composite quartz-host rock particles for subsequent sorting with very high recovery of 95 to 99%. In addition, ore often preferentially fractures along the quartz-host rock contact zone in the crushing circuit. This behavior helps because it liberates more quartz for detection.The feasibility of sorting is investigated for four gold projects in Northern Europe with similar mineralogy. This includes geometallurgical evaluation, amenability testing, small scale “mini-bulk” factory testing in full scale sensor based sorting. The results of the various tests are presented and basic feasibility demonstrated with information on flow sheet development. In addition, the amenability process is evaluated and recommendations made for future projects."

Jan 1, 2017

By Hamid-Reza Manouchehri

Mining & Sustainability? A Paradox?! ? Production: gradually or exponentially increasing (giant mining) ? Ore Grades: gradually declining, ? Open Cut Mining: now widespread, likely to be sustained in the future though the long-term is hard to predict as new mineral deposits are likely to be deeper ? Waste Rock / Overburden: increasing rapidly, likely to be sustained in the future and closely linked to open cut mining, especially for coal and base metals ? Economic Resources: commonly increasing but some remain stable or gradually declining, future is linked closely to exploration, technology and economics; Increasing population, changing life style and technology development, ultimately result in sustainability in mining industry to hang in the balance and continue.

May 1, 2013

By Ingrid Hann

The Triple Bottom Line ? Economic Sustainability ? Creation of Joint Venture companies ? Planned evaluation of other kimberlites ? Social Sustainability ? Impact Benefit Agreement and Participation Agreements ? Education and training initiatives ? Environmental Sustainability ? Environmental management ? Mine closure planning

May 1, 2008

"The link between ore texture and mineral liberation has previously been established at a microscopic scale. To construct ore texture models that can be used in mining applications requires this relationship to be retained at a significantly larger scale. This is initially dealt with by finding a basic set of microtextures that form the elements of the ore textures at the next larger mesoscopic scale, simulating these mesotextures at a fine scale, then changing the support of the mesotexture simulations to generate the expected mining block/stope mesotexture distributions. Thus, a mutually exclusive and exhaustive set of spatially locatable mesotextures can be used to fully characterize the metallurgical properties of in situ material.A method that generates expected distributions of mesotextures for any mining block size or shape is proposed, and includes: (1) characterizing the spatial correlation of the set of mesotextures with a single covariance function; (2) generating multiple simulations of mesotextures at a fine scale; and (3) using the simulations at a fine scale to generate the expected mining block/stope mesotexture distributions. A case study, using the George Fisher sediment-hosted base metal deposit in Queensland Queensland, Australia, is developed to demonstrate the proposed methodology as well as show the inadequacy of off-the-shelf approaches.Mining-scale texture models can be used to improve the in situ discrimination of ore from waste by exploiting the joint spatial variability of grades and textures to quantify the expected metal recovery of in situ material, then calculate local marginal cut-off grades. An artificial case study is presented to demonstrate the changes in ore/waste selection when considering ore texture models compared to constant metal recoveries."

Jan 1, 2005

By G. M. Ritcey, K. E. Haque, S. H. Lucas

"Laboratory-scale hydrochloric acid leach tests were conducted on an Elliot Lake uranium ore. Hydrochloric acid leaches without an oxidant or with molecular oxygen (i.e., air or pure oxygen gas) as an oxidant favoured uranium and radium extractions. Conditions for maximum uranium, thorium and radium extractions with hydrochloric acid in the presence of sodium chlorate were determined. The highest extractions of uranium (96%), thorium (81%) and radium (91%) were obtained using a mixture of 44.0 kg HCI and 2.5 kg NaCIOJ per tonne of ore at 75°C with 18 hours ' retention.Flowsheets for two-stage leaching are proposed. The residues obtained from the second-stage leach contain uranium (0.002%), thorium (0.006%) and radium (15 to 20 pCi/g). Tailings of this nature are considered suitable for mine backfill, and, if pyrite is removed, suitable for surface disposal.IntroductionThe nuclear energy industry forecasts an increasing demand for uranium. This increasing demand requires not only largescale mining and processing of conventional and complex uranium ores, but also leads to the consideration of new and nonconventional sources of uranium, e.g., black shales, phosphate rocks, granite, sea water and fossil-fuel ash."

Jan 1, 1980