Search Documents

By J. -F. Lepage, M. A. Tomlinson, K. K. Murray

"The Éléonore mine, located in the James Bay region of Northern Quebec, generates a gold bearing flotation concentrate rich in pyrrhotite. Direct leaching of the finely ground concentrate results in high cyanide consumptions and poor recoveries, so effective pre-treatment to passivate the pyrrhotite is required before leaching. Following a number of process upsets at the mine, test work was performed to better understand the requirements for passivation so a more effective operational strategy could be implemented. This paper outlines the testing and implementation of the new strategy at Éléonore.ÉLÉONORE CONCENTRATOR The Éléonore mine is located 800 km north of Montreal, in the James Bay Region of Quebec, Canada. The ore, containing gold disseminated in sulfide minerals and free fine gold in silicate gangue, is crushed in a two-stage crusher plant before being ground in a single 9,000 kW ball mill. The ball mill is in closed circuit, with about 25% of the cyclone underflow passing through a gravity plant with two, 48” Knelson concentrators. Gold recovery in the gravity circuit varies between 15 and 20%, with gravity concentrate leached daily in an Acacia intensive leach reactor. Cyclone overflow, at a target P80 of 65 microns, flows to the flotation plant where the gold bearing sulfide minerals, mainly pyrrhotite and arsenopyrite, are recovered to concentrate with a mass pull of about 5%. The flotation concentrate, typically containing between 80 and 120 g/t of gold, is thickened and finely ground using a 1500 kW Isa Mill. The finely ground concentrate is diluted, to generate a slurry with about 32% solids by weight, before feeding the leach plant. Initially the concentrate slurry is pre-treated with oxygen and lead nitrate, to passivate the sulphide minerals before cyanide is added for gold dissolution. Gold is recovered from the leached slurry using carbon-in-pulp (CIP). The flotation tailings are also thickened and gold is recovered in a dedicated leach-CIP plant."

Jan 1, 2017

By S. Bastola, Y. P. Chugh

"This research determines shear strength and stiffness properties of bedding planes and joints in the roof strata rocks within 7.5 to 9 m (25-30 ft.) overlying the Illinois #6 coal seam (within the pressure arch zone). A shear test loading device was designed into a 1.334 kN (150 t) Forney Compression Loading Machine to perform direct shear tests in accordance with ASTM D5607-08 “Standard Test Method for Performing Laboratory Direct Shear Strength Tests of Rock Specimens under Constant Normal Force”. The data were used to determine peak and residual friction angles and the dilation angle. A total of 49 bedding plane samples were tested, out of which 46 (36 intact and 10 relatively weak and loose) samples passed QA/QC procedures in accordance to ASTM D5607. Samples from eight (8) different bedding planes- shale/limestone (SL), shale/sandstone (SSs), shale/bone (SB), laminated sandstone (LS), shale/shale (SS), bone/bone (BB), bone/limestone (BL), and limestone/limestone (LL) were tested. The number of samples tested for each bedding plane were: SL- 11, SSs- 8, SB- 5, BB- 4, LS- 6, SS- 9, BL- 1, and LL- 2. Peak and residual shear strength values at 2.75 MPa normal stress range 1.06 – 6.26 MPa and 0.82 MPa to 0.82 – 4.14 MPa, respectively. The average normal and shear stiffness values are about 11.98 GPa/m and 3.11 GPa/m. Dilation angles are low (<10?) and negative in some cases. Angle of sliding friction values range from 9? to 42?. Joint Roughness Coefficient (JRC) values were less than 10.INTRODUCTIONRock mass may be defined as the total in situ rock medium containing bedding planes, faults, joints, folds and other structural features. Therefore, it is discontinuous and may have heterogeneous and anisotropic engineering properties. Upon creation of an excavation in a rock mass, bedding planes and joints are the most likely points of failure initiation. The failure typically occurs either in tensile or shear mode. Upon failure initiation stresses are transferred to the neighboring rock mass and the failure progresses until stability is achieved through equilibrium of stresses and strength. An example of this mechanism is development of the pressure arch. This study determined the shear strength and stiffness properties in shear and compression of bedding planes and joints in the immediate roof strata rocks within 7.5-9 m ( 25-30 ft.) overlying the Illinois No. 6 coal seam (within the pressure arch zone). Since such data are currently not available for Illinois Coal Basin mines, researchers and engineers have been using estimated values for design purposes. The immediate roof lithology in the proposed mining area consists of shale 0.62 m; Bone 0.09 m (0.3 ft.); Limestone, 0.10 m (0.33 ft.); Shale 2.37 m (7.9 ft.); and sandstone 0.55 m (1.83 ft.). The bedding plane samples were provided by a mine in south-eastern Illinois operating at a depth of about 180 m (600 ft.)."

Jan 1, 2015

By C. Pichler, S. Luidold, C. Wagner, C. Sagadin, D. Kreuzer

Engineers and scientists have been combating the attack upon refractory materials of molten metals/matte and slags for hundreds of years. The details in many cases are still questionable or at least debatable. The corrosion is a major concern for furnace operators as refractory wear or failures inevitably results in reduced production efficiency and furnace reliability. Also the cost to industry is considerable and only a thorough understanding of all the complexities of the process will help to minimize that cost. One of the critical questions to overcome is the correct selection of refractories for the individual process steps to provide long and predictable refractory life together with high furnace availability. To understand the nature of the reactions involved in refractory corrosion, it is crucial to determine the complex thermo- chemical equilibria of the reactions occurring between the refractory materials and the process phases. A simulation model coupled with commercial software like FactSageTM is demonstrated aiming to understand the corrosion mechanisms between refractories and the molten process phases and draw implications for improving the performance of refractories and refractory lifetime. INTRODUCTION The extraction or recycling of valuable materials, e.g. metals, can be done by two main routes, pyro- and/or hydrometallurgical processing, depending on the chemical behavior of the used ore, scrap or pre-treated concentrate. Sometimes it is also necessary to use both process routes for the extraction or the recycling of valuable materials. In the case of a pyrometallurgical treatment, the usage of refractory materials is inevitable. This is mainly caused by high temperatures, prevailing during processing. The interaction between refractory material and slag, metal or matte leads to different reactions and interactions. As a main result corrosion of the furnace lining (refractory material) takes place. Hence, recurring furnace shutdowns occur for renewing the refractories. This leads to reduced production efficiency. Such refractory lifetimes are between some hours and decades, depending on the processes.

Jan 1, 2019

By L. Tong

The nickel laterite ore is composed of soft and hard minerals, and nickel distributes preferentially into the soft mineral rather than in the hard. Selective comminution of saprolitic and goethitic nickel laterites is investigated to upgrade nickel into the fine fraction using stirred milling. The optimal selective grinding conditions were determined through a kinetic study and the limit of selective grinding and nickel upgrade was analyzed. The breakage rates of minerals, grinding time, and the weight ratio of soft and hard minerals in the feed play an important role in selective grinding. A small breakage rate on hard minerals and a large breakage rate difference between the minerals are optimum for selective grinding. The soft mineral grade decreases with grinding time and the optimum grinding time is a trade-off of the soft mineral upgrade and recovery. The minerals weight ratio determines the limit of selective grinding. The effect of nickel upgrade is determined by both the conditions that influence selective comminution and the nickel grades in both the soft and hard minerals. The nickel grade in the soft mineral determines the limit of nickel upgrade.

Jan 1, 2015

By D. R. Pyke

Many of the gold deposits in the Timmins• area show a close spatial association to ultramafic metavolcanics. Available analytical data suggest that ultramafic rocks contain significantly higher gold contents than other major rock types. In addition, recent analyses by Keays (1975) suggest that talc-carbonate alteration of ultramafic rocks releases significant quantities of gold. It is proposed that the ultramafic volcanics formed the principal source of gold for the deposits in Timmins, and that the gold was derived from the ultramafic flows when they were extensively carbonatized. Carbonatization of the ultramafic rocks and emplacement of the auriferous quartz-carbonate veins was probably coincident with the last major period of deformation in the gold camp. Delineation of hitherto unrecognized ultramafic volcanics could be an important guide to the discovery of further gold deposits.

Jan 1, 1976

By T. Gerritsen, T. Plikas, K. Ochoa, M. Loveless, R. MacRosty, J. Reichart, R. Pula

Sidewall accretion in a smelting furnace plays an important role in furnace integrity as it provides protection to the sidewall cooling elements and thereby extends the furnace campaign life. The extreme thermal and mechanical stresses in the furnace and changes in the slag chemistry can cause the sidewall accretion to melt or break away decreasing the lining protecting the cooling elements. Thin accretion is highly undesirable as it increases the risk of exposing the cooling elements to the molten bath and in the worst case may lead to a failure. Therefore, monitoring the sidewall accretion on an operating furnace is extremely important to manage furnace integrity and to support safe furnace operation. Operators often generate estimates for sidewall accretion and refractory thickness using either copper cooler temperatures or heat load into the cooling water circuits. Multivariate statistical models, on the other hand, have the capability to consider all the process measurements simultaneously to provide a more reliable estimate. This paper describes the application of multivariate statistical models for sidewall integrity monitoring on a Flash Converting Furnace (FCF) and also discusses the online implementation of these models as the Sidewall Accretion Monitoring System. INTRODUCTION Rio Tinto’s Kennecott Utah Copper (KUC) smelter located near Salt Lake city, Utah operates a Flash Smelting Furnace (FSF) and a Flash Converting Furnace (FCF) to produce high-grade matte and blister copper respectively. Since the commissioning of smelter in 1995, several improvements were made to these furnaces to increase their efficiency and operational safety. At present, Kennecott smelter is known to be among the lowest-emission and highest energy recovery copper smelters in the world. Since the smelter start-up, Kennecott has invested in several advanced furnace monitoring practices to evaluate the integrity of the furnaces and improve their campaign life. An example is their temperature monitoring system installed for the smelting and converting furnaces, which continuously monitors the furnace sidewall temperatures and notifies the operators during temperature excursions. During an investigation on the converting furnace, it was revealed that there were frequent temperature excursions in the settler sidewall area towards the reaction shaft end of the furnace that caused significant furnace downtime. The reason for the sidewall temperature excursions was not clearly known.

Jan 1, 2019

By Simon C. Dominy, Ian M. Platten, Garry F. Johansen, Alwyn E. Annels, Brian W. Cuffley

Abstract - Coarse gold-bearing veins are characterized by high grades that are localized and erratic. Effective sampling of coarse gold-bearing veins is difficult because of the low concentration and erratic nature of the gold particles. Diamond drilling is an effective measure of geological continuity, however, grade distribution can only be reliably obtained from underground development (including close-spaced sampling, bulk sampling, and trial mining). Comparison between surface and underground drilling, underground linear/panel and bulk sampling indicate that drilling and linear/ panel samples generally understate bulk sample grades. Bulk samples are likely to be the closest estimators of true grade. It is unlikely that anything above an Inferred Resource category can be estimated from surface drilling alone, and at best the grade will only be a global estimate. Underground development, in-fill drilling and bulk sampling/trial mining will be required to delineate Indicated and Measured Resources. Closely spaced development and bulk sampling is likely to be the only way to determine Reserves. The resource estimation process must driven by a clear geological model that should attempt to understand both geological and grade continuity. Traditionally, grade interpolation has been undertaken using classical methods, though more recently, computer-based block modelling techniques have been used with some success. Three case histories are presented, documenting the problems of estimating resources in coarse gold-bearing veins and the practical ways in which they were approached.

Jan 1, 2000

By Robert Macdonald, William Coombe, John F. Lewry

Gold occurrences have been known in the La Ronge Domain for many year . Mineable reserves have more recently been outlined and there is every prospect of a major gold camp being established in the domain within this decade. The La Ronge Domain lies in the Lower Proterozoic 'Trans-Hudson Orogen' and is part of a collage of Early Proterozoic crust comprising volcanoplutonic arcs, batholiths, associated volcaniclastics and volcanogenic sediments lying between the Superior Craton to the outheast and the reworked Archean basement/Aphebian cover terrain to the northwest. The domain has several lithostructural subdivisions, the most important of whjch , from a gold exploration point of view, is the Central Metavolcanic Belt. This belt is composed dominantly of a range of metavolcanic rocks and gabbroic to granitic intrusives, which geochemically resemble younger subduction-generated 'primitive' arcs developed on oceanic crust. U-Pb zircon geochronology indicates that the arc volcarusm and pre- to late-kjnematic plutonism occurred about 1890 Ma to 1850 Ma ago. The belt has an attained grade of upper greenschist to amphibolite facies and is relatively undeformed , though high strain zones occur locally. Most gold occurrences in the La Ronge Domain have been found in the Star-Waddy Lakes area of the Central Metavolcanic Belt, and in the Sulprude-MacKay Lakes area to the south which is interpreted as a tectonically dismembered part of the main belt. Both tratiformand vein-type gold occurrences are present in the domain; vein-type predominate and form nearly 90 per cent of the occurrences. The stratiform-type occurrences show a regional lithological a sociation with iron-rich sediments within proximal felsic volcanjc sequences. Some vein-type occurrences appear related to brittle fracturing associated with intrusive emplacement (the magmatic-hydrothermal "syn:' and "subvolcanic" veins) and faulting. However, most of the vein-type occurrences exhibit a spatial association with regionalscale ductile shear and other high strain zones, and were probably formed by metamorphichydrothermal processes.

Jan 1, 1986

By Harry Siewert, Tom Milner, Jack Stickney

"LocationThe Gibraltar mine is located in central British Columbia (NTS 93B/9W), 362 km north of Vancouver. Access is provided by 20 km of paved road from McLeese Lake, which lies 45 km north of Williams Lake on Highway 97. Latitude and longitude of the mine are 52° 30' and 122° 16', respectively.The total area of the McLeese Lake site is approximately 1700 ha (4200 acres). This includes the orebodies, dumps, surface drainage collection system, plant site, roads and tailings ponds.Brief Description of OperationOre is mined by open pit methods and is concentrated using conventional crushing, grinding and flotation processes. Copper and molybdenum flotation occurs at an average rate of 40 000 tons per day. Tailing is discharged to an impoundment area and the water recycled as process water. Additional copper is extracted from the waste dumps using sulphuric acid as a leach solution followed by solvent extraction and electrowinning.HistoryExploration by Gibraltar began in 1964, continuing until late 1970, at which time it was announced that the property would go into production. Construction started in early 1971, with initial production in March 1972. Target capacity of 30 000 tons per day was achieved by the end of March and is currently at 40 000 tons per day.Ore reserves as of January 1, 1998 were 184 384 000 tons grading 0.31% Cu and 0.010% MoS2."

Jan 1, 2000

By D. D. Macdonald, G. Engelhardt

The accumulation of damage due to localized corrosion [pitting, stress corrosion cracking (SCC), corrosion fatigue (CF), crevice corrosion (CC), and erosion-corrosion (EC)] in complex industrial systems, such as power plants, refineries, desalination systems, etc., poses a threat to continued safe and economic operation, primarily because of the sudden, catastrophic nature of the resulting failures. Of particular interest in managing these forms of damage is the development of robust algorithms that can be used to predict the integrated damage as a function of time and as a function of the operating conditions of the system. Because complex systems of the same design rapidly become unique, due to differences in operating histories, and because failures are rare events, there is generally insufficient data on any given system to derive reliable empirical models that capture the impact of all (or even some) of the important independent variables. Accordingly, empirical models have generally failed to provide a robust basis for predicting the accumulation of corrosion damage in complex systems under realistic operating conditions. The alternative prediction philosophy is determinism, in which the development of damage is described in terms of valid, physico-electrochemical mechanisms with the output being constrained by the natural laws. The differential damage is then integrated along the corrosion evolutionary path for the system (i.e., over the future operating "history") to yield the desired integrated damage, which is the quantity that is most useful to an operator. In this paper, we review the theory of predicting corrosion damage within the framework of Damage Function Analysis (DFA), with particular emphasis on the pitting of aluminum in chloride solutions and on the accumulation of damage from SCC in Type 304 SS components in the primary coolant circuits of Boiling Water (Nuclear) Reactors (BWRs). These cases have been selected to illustrate the various phases through which localized corrosion damage occurs.

Jan 1, 2005

By S. J. Prout, J. M. Lang, D. Lascelles, K. Sarinas

"There is a growing demand for ore characterization methods to support metallurgical development programs from a true geometallurgical perspective. Today, there are multiple automated mineral analysis systems on the market, many of which are based on conventional mineral liberation data. However, liberation data can be limited when assessing the floatability of a mineral to predict its recovery as it doesn’t consider the surface area available for collector absorption and bubble attachment; whereas mineral exposure measurements can. Using the First-Order Rate equation to predict the recovery versus time of variously exposed particles, a model has been developed to predict the recovery of copper sulphides at a particular grind size. This model provides the opportunity for the prediction of copper recovery and grade from multiple, small-scale samples. These predicted values can be imported into resource modeling software, and guide the domaining of geometallurgical units within the ore body. Data has been analyzed from various global copper porphyry systems and compared with actual flotation testwork.IntroductionAs part of the development of a mining project, resource estimation primarily focuses on the definition of the quantity and grade of the ore in the deposit; as the project evolves from preliminary economic assessment through to feasibility, the geological model is usually further populated with hardness and recovery data.The CIM Definition Standards (2011) identifies measured mineral resource as the part of a mineral resource for which quantity, grade or quality, densities, shape, and physical characteristics are estimated with confidence sufficient to allow the application of “modifying factors” to support detailed mine planning and final evaluation of the economic viability of the deposit as an asset. The modifying factors include, but are not restricted to, mining, processing, metallurgical, infrastructure, economic, marketing, legal, environmental, social and governmental factors.With market fluctuations, many investors in the mining industry have become more and more risk averse which has increased the demand for more reliable data to support these modifying factors. This has led to the widespread use of geometallurgy and statistical analysis to better inform the resource estimation. Geometallurgy is used to characterize ore variability and is especially useful for highly variable or strongly zoned deposits, several close deposits that will be milled together, projects requiring complex or new metallurgical approaches, brownfields or sight-of-mine exploration, expansion projects that exploit new, deeper or adjacent reserves, and projects with significant legacy drill core that are being re-evaluated due to new economic circumstances."

Jan 1, 2018

By I. H. Warren, Forward F. A

The reduction of aqueous slurries of uranyl carbonate at elevated temperature with compressed hydrogen m the presence of metal catalysts and certain organic promoters has been shown. to yield uranium dioxide. The reduction takes place in a sequence of steps. The purity and sintering properties of the dioxide make it of interest as a starting material for fuel element production. Simple control can be exercised over the surface area and oxygen/uranium ratio of the product during reduction. URANIUM dioxide for fueling atomic power reactors 1s conventionally produced as a powder by simultaneously decomposing and reducing ammonium diuranate with hydrogen in a furnace at high temperature. Fuel elements are then generally made from this powder by compacting and sintering ( 1). In order that elements approaching theoretical density may be obtained,

Jan 1, 1961

By P. Simon, G. Falkinger, G. Angerer, B. Gerold

"This contribution presents an investigation of the evolution of shrinkage pores during hot rolling with a special focus on the microscopic mechanism. The reliable closure of pores, which inevitably occur during the casting process, is of crucial technological importance for high-quality hot rolled plate products. Therefore, lab-scale tests were carried out under different typical thermomechanical loadings. Extensive data from optical microscopy was collected before and after deformation. The analysis shows that the average volume of pores evolves similar to the volume of an idealized arrangement of voids in an ideally plastic matrix. The average shape of the shrinkage pores, however, was found to be almost constant during deformation. Even though individual pores exhibit complex morphologies far from any idealized geometries, the overall evolution of a large number of pores is well captured by simple assumptions. In addition to the quantitative analysis, a schematic representation of this counter-intuitive behavior is provided. A simple ‘Gurson’-type void evolution equation was implemented in a three-dimensional Finite-Element model of the industrial hot rolling process. With the help of this mechanism-based process simulation the thermomechanical closure of shrinkage pores during the rolling process has been optimized for a variety of plate products.INTRODUCTION Aluminum alloys of the 7xxx series are widely used in the aircraft industry. They have to meet high quality standards regarding microstructure as well as mechanical properties. For hot-rolled aircraft plates, one of the most important quality requirements is that they are free from pores. Pores, however, are inevitably created during the casting process either due to shrinkage or due to the dissolution of gas from the melt. The pores have to be closed mechanically during the hot-rolling process. Therefore, the mechanism of so-called pore closure or void closure has a high technological relevance for the production of aircraft plates. The behaviour of voids in a ductile matrix subjected to mechanical deformation has been extensively studied, especially in the context of damage mechanics. A recent review (Besson et al., 2010) on modeling methods for ductile damage gives a good impression on how much experimental as well as theoretical effort has been dedicated to the problem of void evolution under mechanical loadings. Although void closure has been studied to a far lesser degree, it obeys to the same general theoretical evolution laws as void growth. The most basic theoretical result is that hydrostatic pressure drives void closure, while hydrostatic tension leads to void growth. The mechanism of void closure depends on the void shape. This is illustrated by the example of a flat penny-shaped void, which under compression obviously closes much faster than a sphere with the same volume. Theoretical models have been developed for the evolution of simplified void geometries, such as spheres or cylinders (e.g. Gurson, 1977), spheroidal (Gologanu et al., 1997) and ellipsoidal voids (Ponte-Castaneda, 1994). In industrial cast ingots, however, the pores exhibit very complex morphologies, which are far from any idealized geometry. X-ray tomography revealed ‘tortuous’ voids in a 5xxx aluminium alloy (Chaijaruwanich et al., 2006)."

Jan 1, 2018

By Alfred W. G. Wilson

MR. F. E. LATHE: In studying any subject whatever, one should at least occasionally stand back from the canvas, as it were, and take a broad view of the picture. It is such a view of the subject of industrial minerals that Dr. Wilson has given us today, and, in consideration of our efforts to utilize Canada&apos;s resources to the utmost in the present emergency, it seems most timely. I shall confine my remarks on the subject to the resources of the atmosphere and hydrosphere. We seldom stop to realize our dependence upon the atmosphere, not merely as a source of the oxygen we breathe but also of other indispensable elements. As recently as the beginning of the present century, grave concern was felt lest the rapidly increasing population of the world should ultimately starve for lack of the nitrogen required for crop growth. I recently noticed a reference to the Scientific American for March, 1890-just fifty years ago-in which an account is given of work on the fixation of nitrogen, which, said the article, "leads to the conclusion that while cyanides and ammonia may be thus produced experimentally, there are as yet insuperable difficulties in the way of adapting those methods to industrial purposes". Y et, in the early part of the present century, the development of the arc, cyanamide, and synthetic ammonia processes of nitrogen fixation was such as to remove, for all time to come the possibility of a shortage of nitrogen. Today, the atmosphere is by far our greatest source of nitrogen, and the capacity of the nitrogen fixation plants of the world is at least 4,000,000 tons annually-much more than can at present be utilized. Pure oxygen or oxygen-enriched air offers great possibilities in metallurgy and industrial chemistry, but, so far, little application has been made. In a paper presented to the Institute in 1926, 1 pointed out the theoretical savings which could be effected by the use of oxygen in burning carbon-when the gases pass off at 2,460°F., the fuel saving is no less than 50 percent. The use of oxygen on a commercial scale is intimately tied up with the question of refractories, but we should not forget that the possible changes in metallurgical practice by the use of oxygen are truly of revolutionary character.

Jan 1, 1940

By Andrew Kerr

Overview of Presentation ? Introduction ? An historical context: From 1866 to the 21st century. ? Geological framework for iron ore in the region known as the ?Labrador Trough?. ? Producing iron-ore deposits of the Labrador City ? Wabush area, and near-future production from the Schefferville area. ? Exploration projects representing potential future production?.or expansion of the district. ? Some concluding remarks???

May 1, 2011

"Load-haul-dump machines (LHDs) are typically used in underground metal mining operations. Delays or inappropriate use of LHDs can result in production loss. Optimized LHD use is especially crucial in larger mines because longer travel distances increase heat, dust, and gas emissions, which in turn increase ventilation costs. This study, conducted at an existing Swedish sublevel cave underground mine, used discrete event simulation and the AutoMod™ DES tool to determine the ventilation costs related to using too many diesel LHDs in a production area with reduced ore pass availability. When fewer ore passes are available, ventilation costs related to operating LHDs in the production area were found to increase by as much as 200, 224, and 306% for one, three, and six LHDs in operation, respectively. ¦ KEYWORDS Discrete event simulation (DES), Loading operations, Production rate, Ventilation costs RÉSUMÉ Dans les exploitations souterraines d’extraction des métaux, on utilise généralement des chargeurs-transporteurs (LHD, de l’anglais Load-haul-dump machines). Les retards ou l’utilisation abusive des LHD peuvent entraîner une perte de production. L’utilisation optimisée des LHD est particulièrement importante dans les grandes mines en raison des longues distances parcourues, lesquelles augmentent la chaleur, la poussière et les émissions de gaz qui, à leur tour, décuplent les coûts de l’aérage. Cette étude, menée en Suède dans une mine souterraine utilisant la méthode d’exploitation en sous étages avec foudroyage, s’est basée sur la simulation à événements discrets (SED) et l’outil de SED AutoMod™ pour déterminer les coûts de l’aérage liés à l’utilisation d’un nombre trop élevé de LHD alimentés au diesel dans la zone de production, avec une disponibilité réduite de la cheminée à minerai. Lorsque les mines disposent de moins de cheminées à minerai, l’étude montre que les coûts de l’aérage liés à l’exploitation des LHD dans la zone de production augmentent respectivement de 200, 224 et 306 % pour un, trois et six LHD en fonctionnement. ¦ MOTS CLÉS coûts de l’aérage, opérations de chargement, simulation à événements discrets (SED), taux de productionINTRODUCTION Transporting material from the mine face to the dumping location requires flexible loading and hauling equipment that is able to cope with sharp curves and a complex mining environment. Load-haul-dump machines (LHDs) are designed for such an environment. Models are available to suit specific features of the working environment such as small, large, or narrow open stopes (Atlas Copco Rock Drills AB, 2007). When carrying a full load, haulage speed is higher for LHDs than for front-end loaders with the same engine size. Also, payloads are approximately 50% higher for LHDs than for front-end loaders (Atlas Copco Rock Drills AB, 2007). LHDs are capable of climbing steep (Bloss, Harvey, Grant, & Routley, 2011). The haulage distance between stope and ore pass is usually between 50 m and 400 m. LHDs are efficient for tramming distances up to 200 m (Bloss et al., 2011), whereas when loading trucks, the LHDs work efficiently when the distance is less than 100 m (Atlas Copco Rock Drills AB, 2007). The largest diesel-powered LHDs, with drive motors of up to 350 kW, can handle a payload of 21 t (Wennmohs, 2014). Most mining equipment runs on diesel fuel, which provides flexibility, high durability, and high efficiency (Pronk, Coble, & Stewart, 2009); however, other alternatives such as electric, hybrid diesel/electric, or hydrogen fuel cell machines are increasingly being developed and used. This change is due to diesel-powered machines accounting for a significant portion of the ventilation costs in the mine (Chadwick, 2008; Paraszczak, Laflamme, & Fytas, 2013). Currently, as part of the European sustainable intelligent mining systems (SIMS) project, Epiroc AB is planning to demonstrate technology for a diesel-free underground mine at Agnico Eagle’s Kittlä mine in Finland using"

Jan 1, 2019

By Cesar Carrasco

Mine reconciliation is the art and science of comparing predictions and real-world outcomes with the intent of revealing the true quality of performance of models, planning, mining, and mineral processing. When mine reconciliation is conducted in a systematic, transparent and sustainable way it can play a central role in the governance of Mineral Resource and Mineral Reserve (MRMR) estimation and reporting. The core processes of modelling, planning, mining, and processing need to be transparent to be able to demonstrate that MRMR are reliable predictors of mine performance and value. Transparency is also necessary for mine technical staff to generate meaningful analyses, conclusions, and business improvement actions that demonstrably maximise value for all stakeholders. Most mines have some form of mine reconciliation practice, however because there is no agreed industry standard, and because mine reconciliation is difficult for a variety of reasons, it is often unsustained and/or ineffective at delivering the required transparency of performance. To deliver true governance of MRMR and business value, mine reconciliation must be sustainable. There are two categories of issues that combine to make mine reconciliation extremely difficult to sustain, these are technical, and people related. Technical issues include defining standard terms, accurately tracking material flows, data availability/adequacy/quality, calculation of key performance indicators and tolerance limits, analysis, and interpretation of results, understanding limitations of modelling techniques, and defining appropriate actions that can deliver value. These technical challenges are non-trivial, however compounding these are a range of people issues that include personal agendas, scepticism, lack of knowledge and experience, poor teamwork, absent leadership, toxic workplace culture, staff turnover, ineffective communication, siloed organisational structure, and lack of deliberate change management. All these problems can be solved with clarity of purpose, definition of the process of mine reconciliation, discipline in following the process, appropriate resourcing, and commitment to success across the entire organisation. Outlined in this paper is a management system that delivers sustainable mine reconciliation by addressing both the technical and people issues described above. This approach can deliver significant value for a mine and adds a robust, defensible governance over MRMR estimation and reporting.

Oct 1, 2024

By J. A. Russell

IT IS the purpose of this paper to show how the design of the larger slope hoists in use in the mines of the Dominion Steel and Coal Corporation has tended to evolve ta suit the particular conditions of operation. These hoists are all used for hauling coal in trains or trips of pit tubs up the mine slopes, which usually follow the dip of the seam . As the mine is developed to the dip and the slope grows in length, the length of the rope and the size of the hoist required to handle it rends to become extremely cumbersome. It has been found that the best economic conditions of hoisting are obtained when the length of the slope is limited to about seven or eight thousand feet. Beyond this length it is necessary to offset to one side of the line of slope and start a second or auxiliary slope, which will be served by its own hoist installed underground. With this hoisting distance as a basis, we find that we can economically hoist the outputs required, usually about 1,500 tans per eight hours per slope, by hoisting the coal in trips of about twenty boxes. This, on the grades obtaining, will require a rope of about l 1/4in. diameter, running at a speed of 1,200 ta 1,800 feet per minute, and requiring from 1,200 to 1,800 h.p. at the hoist shaft. The tendency is for the rope speeds of the surface hoists to be a little higher than the underground hoists which relay to them, so that the surface hoist has a small margin of time in hand. The oldest surface hoists were steam-driven, but, with few exceptions, these have given place to electric hoists. With the exception of one hoist, which was altered in design, the steam hoists have not had the opportunity of evolving in the same way as the electric hoists, and will not be mentioned any further.

Jan 1, 1944

By D. Royston

In SAG mills fed with a variety of ore types, hard packing between the shell lifters can come and go depending on rock type and rock size distribution and the presence of a binder. Packing can appear in all sizes of SAG mills, and can be tenacious. High ball impact forces (depending on ball size) in larger mills may compact and encourage packing. Packing can have a negative impact on milling performance and a change in shell liner design may be required to remove it. However shell liner design changes need to be managed with care to ensure liner reliability. In smaller mills control of packing can extend shell plate wear-life and may help to maintain milling performance in fixed-speed mills through the liner wear-cycle.

Jan 1, 2012

By W. F. Harkness, D. Hodgkinson

"A non-destructive testing program was established at Crows Nest Resources (C.N.R.), Line Creek mining operation following an in-service fatigue failure of a front wheel spindle on a large haulage truck.This failure identified a definite need for improvements in the ultrasonic techniques used during the mandatory spindle integrity examinations. Initial investigations using common mining industry ultrasonic examination techniques showed that the smallest detectable cracks were 75 mm in length for the spindle types in service at the C.N.R. site. The Initial findings indicated that inadequate inspection technique design was the cause of the poor performance. To improve inspection reliability it was identified that improved ultrasonic techniques were required. Results using designed ultrasonic techniques were encouraging, with the detection of simulated and natural cracks 12 mm long achieved. The cost benefits associated with the extended spindle life, following the removal of these small fatigue cracks, far exceeded those of the expertise and effort necessary to implement and conduct the N.D.T. program.Introduction During 50 years of evolution, non-destructive testing (N.D. T.) has progressed from a laboratory curiosity to a well accepted and invaluable tool used in the assessment of material integrity. Unlike destructive testing, N.D.T. does not deform or render the material useless. Non-destructive tests may involve many applications, from the determination of a corrosion prevention coating thickness to the examination of a raw material for internal and external deformities.Within the mining sector, highly-stressed components will normally have been subjected to some form of non-destructive test during their manufacturing cycle. These tests are used to ensure the component does not contain material flaws whichmay be detrimental to its service performance.While the component may have assured quality when produced, deterioration by fatigue may occur during an aggressive service life. Large dynamically-loaded components such as haulage truck front wheel spindles are , in particular, prone to this service related problem."

Jan 1, 1987