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By Martin Landwehr

"Dust samplers are based on different principles. The konimeter is based on the number of particles counted; mining applications are based on routine sampling; and the photometrical evaluation of samples is used after the pre-separation of particles above 5 micron by the mining konimeter. In special cases, the Draeger sampler is used for quantitative analysis. General trends are toward larger samples, concentration on a weight basis, fractionation into size groups by different techniques and an analysis of composition. Standards or TLVs already exist in all industries. Surface industries base their criteria on concentrations and quartz contents in particles below 5 micron. The mining industry uses the tyndalloscope routinely to determine concentrations; concurrent] y, the rock content, as deter-mined by ashing samples, is obtained by konimeter.Threshold limits are related to the rock content in respirable fractions and tyndallometrically determined concentrations. The TL Vs are based empirically on Landwehr's ""dust values,"" as agreed upon with the Mines Inspectorates. Recently, and in accurate sampling, dust samplers have been used that count the dust in two fractions -above and below 5 microns. Mineral composition is determined either for all minerais or just for quartz. In assessing the dust hazard by Landwehr's ""dust values,"" all minerais are taken into consideration; in coal dust sampling, however, only the quartz content is taken into account. Efforts are now being made to co-ordinate the different assessment methods, arriving at uniform MAC values in agreement with those of other countries."

Jan 1, 1969

Several inorganic reagents and organic polymers were tested as depressants in the single mineral flotation of ultrafine iron oxide and hydroxylapatite with Dowfroth 250 as a frother. It was observed that the inorganic reagents and the low molecular weight polymers generally caused dispersion of the ultrafine particles, and consequently their recovery into froth products more or less equaled the recovery of water. On the other hand, the high molecular weight polymers caused different degrees of flocculation of the ultrafine particles, and their recoveries were much lower than the recovery of water. These observations pointed to a need to re-define flotation depressants in fine particle flotation. The traditional definition of a flotation depressant, i.e., to make particle surfaces hydrophilic by forming a hydrophilic film and/or by removing collector and activator coatings, is sufficient for relatively coarse particles. However, to prevent fine and ultrafine particles from floating, a successful depressant should not only make the particles hydrophilic, but also enlarge the particle sizes so that they do not enter the froth product by mechanical entrainment. Polymeric depressants are ideal for these purposes. The different schemes to use polymeric depressants in the selective flotation of fine and ultrafine particles were discussed These schemes involve the integration of the polymeric depressants into other size enlargement processes such as shear flocculation, oil agglomeration, etc., for hydrophobic particles.

Jan 1, 2004

By H. S. Wilson

"The property owned by the Lamaque Mining Company comprises a group of forty-four claims and fractions occupying an area of about 2,458 acres, in west-central Bourlamaque township, Abitibi county, Quebec. It is on ,the outskirts of the towns of Bourlamaque and Val d'Or, about 70 miles east of Noranda, near the eastern end of the belt of greenstones of Keewatin and Timiskaming age that extends eastward through Kirkland Lake into northwestern Quebec, terminating in Haig and Jurie townships 40 miles to the east.The claims on which the orebodies occur were first staked in 1923; No. 3 vein was discovered the following year. The original discovery was made by R. Clark in 1923. This was a small quartz vein containing a pocket of coarse gold on the north side of a hill near the northwestern corner of block 3. It is said that all the gold was removed in one shot in blasting into the vein; elsewhere it was barren. A picket line was then run west along the strike of the vein, which occupied a narrow shear zone, and about 2,000 feet west, in prospecting on either side of the picket line, a large boulder of quartz and tourmaline containing visible gold was found. This led to more intensive prospecting by trenching in the vicinity with the result that the No. 3, or 'float' vein, about 250 feet north of the boulder, was found. Due to low ground this vein was exposed in only one trench. The only other important vein found on the surface was the No. 1, or H, vein, which was exposed in several places by stripping and trenching, but it did not carry appreciable amounts of gold."

Jan 1, 1954

By H. L. Ramandi, P. Moore

"The corrosion of support bolts in underground mines has become an increasingly prevalent issue over the past two decades. With an increase of premature failures due to Stress Corrosion Cracking (SCC), it is evident that understanding the environmental factor influencing the cable bolt corrosion is critical for maintaining effective ground support hence the safety and productivity of underground spaces. Experimental testing of rock and cable bolts were accomplished in a variety of packings, including saturated clay, saturated coal, mine water and grout/cement to investigate their corrosion behaviours. Water samples were obtained and analysed for pH and electrical conductivity (EC) during the experiment. After a period of 76 days the bolts were retrieved and analysed visually. Primary factors were found to be the presence of geological materials and the aeration of the bolts, i.e. the vicinity to air and air flow, while secondary factors were observed to be pH levels and EC. It was also found that the coal/clay interfaces and the water/grout/cement interfaces are non-relevant to corrosion of rockbolts and cable bolts. The proposed framework can be applied to other reinforcement materials used in underground spaces for improved understanding of corrosion environment.INTRODUCTION Rock bolts and cable bolts are the major reinforcement elements used in mining industry to improve the rockmass properties for safe and productive mining. They are normally used to pin large beams or blocks of rock in underground mines to stabilise the rockmass in the roof (strata) against collapse. The rockbolts are typically low cost hot rolled rebar while cable bolts are composed of strands of wire, normally wound together around a central king wire (Hyett and Bawden, 1993; Vandermaat, 2014). The typical length of the bolts in underground mines is 2.4 m and 4–12 m for rockbolts and cable bolts, respectively (Vandermaat, 2014; Windsor and Thompson, 1997). Cable bolts are much more flexible and usually offer a much higher load capacity than rigid rockbolts. Their increased length and flexibility allows cable bolts longer than the height of a roadway to be used in underground mines."

Jan 1, 2017

By E. Bonsall, J. J. Brummer, A. R. Graham

"A method and device are described for sampling diamond-drill core by cutting a continuous fillet of constant cross section from the cylindrical surface of the core throughout appropriate sample lengths. The apparatus employs a tapered, abrasive-set, cutting wheel, the conical cutting surface of which projects slightly into a rectangular core-guiding trough set parallel to the axis of rotation. The depth of fillet and thus the amount of sample per unit length can be regulated by adjusting the core guides. The freshly cut fillet itself, by engaging in a guide beyond the cutting wheel, acts to prevent rotation of the core during operation of the device.The cuttings which form the sample are normally collected in a tray below the cutting-wheel and appear at about 80 per cent -100 mesh. They require little or no further treatment or comminution before analysis. Speed, economy and convenience of sampling are thus greatly increased as compared with conventional sampling by im-1>act breaking or sawing, followed by crushing, grinding and sub division for assayAssays from fillets (about 1/20 the cross-sectional area of the core) and from 180-degree segments, from the same ninety-three core-samples, representing 431 feet of nickel-copper mineralization, gave the following results:"

Jan 1, 1968

By W. McCombe, G. Remple, L. Zunti, M. Bernardin, L. Nightingale-Mercer

"The McClean Lake Mill is located approximately 700 kilometres north of Saskatoon, Saskatchewan, Canada and is operated by AREVA Resources Canada Inc. (AREVA). The mill was designed to process high grade uranium ores, and has been undergoing a multiyear expansion to increase its production capacity to 24 Mlbs U3O8 per annum, while also undergoing upgrades to allow it to safely transition to processing high grade ores from the Cigar Lake Mine. During the metallurgical test work on the Cigar Lake ores, it was identified that some ore zones in the Cigar Lake deposit have a propensity to generate hydrogen gas during acid leaching. Hydrogen is a volatile and explosive gas, which poses obvious safety concerns in the leaching circuit. Uranium processing is further complicated by the fact that an oxidant in the form of oxygen gas or hydrogen peroxide is required to regenerate iron in the leach, which further increases the risk from hydrogen gas. During 2013 Hatch and AREVA designed and engineered a number of novel upgrades for the leaching circuit to mitigate the risk of hydrogen gas evolution in the process. Best in class technology was utilized in addition to control and operating strategy changes to ensure the leaching circuit can be safely operated with ores that can evolve hydrogen gas. This paper reviews the design concepts and modifications implemented on this unique and challenging project.INTRODUCTION The McClean Lake mill was originally designed to process high grade uranium ores, however until 2014 the average ore grade processed was 1%. The facility has been undergoing a multiyear upgrade and expansion to increase its production capacity from 12 to 24 Mlbs U3O8 per annum, while also undergoing upgrades to allow it to safely transition to new high grade ores, averaging 18% U, from the Cigar Lake Mine. During the last round of metallurgical test work on the Cigar Lake ores, it was identified that some ore zones in the Cigar Lake deposit had a higher propensity to generate hydrogen gas during acid leaching than previous test work had indicated. Hydrogen gas is a volatile and explosive gas, which poses obvious safety concerns in the leaching circuit."

Jan 1, 2017

By Dave Price

"Canada is scheduled to become the 4th highest diamond revenue producing country in the world by year 2004 with the already operating Ekati Mine and the anticipated operation of the Jericho Mine in 2002 and the Diavik Mine in 2003.This paper provides an overview of worldwide diamond production statistics and a brief introduction to a diamond processing plant. The dense medium separation (DMS) extraction process is presented and this process is discussed in more detail with respect to the extraction of diamonds in terms of feed preparation, dense medium, dense medium cyclones, ferrosilicon recovery and dense medium cyclone operating efficiencies.INTRODUCTIONThe Ekati Diamond Mine in the Northwest Territories started commercial production of diamonds in the 4* quarter of 1998. At full production, the mine is anticipated to produce annually some 3 million carats of diamonds. The Jericho Mine in Nunavut Territory and the Diavik Mine in the Northwest Territories are anticipated to come into production in the 1'' quarter of 2002 and 1st half of 2003 respectively. The combined annual diamond production of these three mines will total approximately 10.34 million carats by 2004, making Canada the 4~ highest diamond revenue producing country in the world.A diamond processing plant initially utilizes crushing, scrubbing and screening in the beneficiation process to liberate diamonds from kimberlite ore and size the product for further treatment through DMS. Alluvial diamond operations do not require initial crushing and scrubbing but incorporate a feed preparation and sometimes a recrush facility with the DMS plant. The heavy sink product from the DMS, which contains diamonds, is further upgraded through x-ray separation and high intensity magnetic separation prior to producing the final diamond product.DMS is a relatively simple separating principle. A mixture of particles of different density is immersed in a dense fluid, so that particles having a density lower than that of the fluid will float while those of heavier density will sink. The translation of the float-sink principle from a laboratory method to continuous industrial practice offers the prospect of very precise mineral separations based on density differences alone."

Jan 1, 2000

By L. Voisin, K. Yamaguchi, D. G. Mendoza, K. Ltagaki

The behavior of arsenic and antimony in the Cu-0 system was thermodynamically investigated to understand their elimination during a blister-making stage in copper smelting. Firstly, the phase relations in a miscibility gap composed of the liquid slag and copper phases in the Cu-0-As and Cu-0-Sb systems at 1523 K were established by a quenching technique. It was found that arsenic and antimony distributed preferentially into the slag phase in the miscibility gap. Secondly, the activities of arsenic and antimony in the miscibility gap of these systems were determined at 1523 K by using a double Knudsen cell - mass spectrometer method. It was clarified that the activity of arsenic in the copper and slag phases showed the negative deviation from ideality while that of antimony in the copper phase a slightly positive deviation. These data obtained in this study suggest a possibility to eliminate arsenic and antimony by means of over-blowing in a converter after discharging the slag.

Jan 1, 2007

By James E. Wennen

The through-put and energy efficiency of an autogenous (AG) grinding mill are adversely affected by variability in rock size and rock competency. This applies to both fully autogenous and semi-autogenous (SAG) grinding circuits. In this paper we focus on an approach to overcome the problem of inconsistent mill through-put related to variability in mill feed size and rock competency. The focus is on ores containing hard, competent rock. This approach consists of preparing feed to an autogenous mill that contains 20% coarse media rock and 80% of material crushed to pass 37 mm. Results of pilot-scale testing for two iron-ores will be presented to show that a 10% to 12% reduction in unit energy consumption is possible with prepared feed, compared with feeding the mill with conventional primary crusher discharge.

Jan 1, 2012

"Conveyed coal flows have been diverted on the basis of real time ash analysis since the 1980s. Many coarse particle separation methods are available through screens, jigs, heavy media separation, particle sorters, to name a few, however bulk diversion requires a representative, continuous analysis to ensure diversion decisions can be made with confidence. Sensors also need to be able to provide measurements at useful time increments so that small tonnages can be diverted for maximum selectivity. Particle separation typically requires high capital costs and there are limitations either in throughput tonnage or particle size or both. Few techniques are able to provide robust and representative analysis of conveyed flows in a useful time basis. Prompt Gamma Neutron Activation Analysis provides multi-elemental analysis of conveyed bulk materials and has been proven in the minerals industry since 2003. This paper outlines the success of this technology in minerals applications in iron ore, phosphate rock and most recently in copper-gold ores, including its use in bulk diversion.INTRODUCTION Naturally occurring quality variability, or heterogeneity, in mineral deposits enables separation and recovery of the valuable components through mining and processing operations. There are distinct advantages in processing the minimum quantity of material to achieve the highest possible yield. Unfortunately, declining ore grades has resulted in larger scale operations and a subsequent loss in selectivity for mining operations. As limits are approached on the practical size of equipment, there is more motivation to investigate alternative solutions. Mining companies are subject to increasing social resistance to growing waste disposal requirements in addition to higher energy and transport costs. Major savings are available by reducing the quantities of material processed where pre-concentration can be effectively applied at early stages in the process. One of the simplest ways to pre-concentrate is to measure the bulk material and reject waste soon after mining so that minimal expense is incurred and that only higher quality material is sent to processing operations. This bulk sorting can occur within the mining operations and has major benefits through energy and other consumables savings. This paper discusses the application of real time analysis technologies suitable for bulk sorting within the minerals industry. Technology that has proven representative for conveyed material bulk analysis and its successful applications to date is explained. Analysis using a sensing technique is only one component of a successful bulk sorting process; the importance of effective diversion systems and a bulk sorting strategy are also discussed. The bulk sorting stage may be one component of a system that could include additional downstream technologies such as particle based sorting systems on a diverted stream."

Jan 1, 2018

By A. K. Ratte, C. M. Brown

"IntroductionIn autogenous mills, grinding of the ore feed is accomplished by the direct action of the variously sized rocks making up the feed on each other and the mill interior. Size reduction is achieved without the addition of grinding media foreign to the mill feed, differing in this respect from rod, ball, and pebble milling. The term ""semi-autogenous"" has entered common usage in the industry to describe autogenous mills to which supplementary grinding ball additions are made to increase the rate at which size reduction of the mill feed occurs, beyond that achieved solely by the action of rock on rock. In a semi-autogenous grinding (SAG) mill, 50Jo to 10% of the mill volume may be occupied by grinding balls, whereas a range of 25% to 45% is more usual in ball milling.The comminution of mineral ores using ""conventional"" techniques has been described in previous papers. In conventional operations, size reduction of mined ore, and liberation of the valuable mineral content, is typically accomplished using flowsheets employing two to four stages of crushing. Crushing is followed by one to three stages of grinding and classification using various combinations of rod, ball, and pebble mills. This paper describes operations employing autogenous or semiautogenous grinding as the principal stage in the comminution process. Primary crusher discharge, or in some instances run of mine ore, is fed directly to an autogenous or semi-autogenous grinding circuit. Final product sizing may be accomplished in a single grinding stage, the mills operating in closed circuit with classification equipment, or in several stages using autogenous and semi-autogenous mills for primary grinding, and ball or pebble mills for secondary grinding. In several operations a portion of the primary mill discharge is crushed in an intermediate comminution step, these circuits being called autogenousball- crusher circuits (ABC). Many different flowsheets exist, but common and important to most are crushed ore stockpiles, reclaim feeder and mill feed conveyor systems, pumps, screens, and classifiers. Autogenous grinding is employed in both wet and dry processes, although today wet predominate."

Jan 1, 1989

By Guocheng Pan

"Although many factors play roles in the estimation of recoverable reserves, smoothing effect and conditional bias are considered major geostatistical issues in the estimation. This paper introduces measures for smoothing effect and conditional bias, and provides insights into their relation to the estimation of recoverable reserves. Both smoothing effect and conditional bias are intrinsic to the information effect and kriging estimators. For a given level of drilling information, however, it is possible to identify the optimal search radius that minimizes conditional bias. Furthermore, it is also feasible to define variance correction factor for reduction of the smoothing effect from exploration block models. Both of these components are key to the accurate estimation of recoverable reserves. IntroductionThe accurate estimation of recoverable reserves is critical to decision making in different phases of feasibility study and mine planning. Much attention for improving the methodology of estimation has been focussed on the effect of the change-of-support (Parker, 1980; Dagdelen, 1996). For example, it is essential to make a volume- variance correction to the estimate of multiple indicator kriging (Hoerger, 1992). When the size of block, b, in the geostatistical model differs from that of selective mining unit (SMU), v, a volume-variance correction is warranted for the prediction of recoverable reserves.Most mining plans and decisions are made prior to the availability of high density blast-hole samples. In most mining operations, the true SMU grade Zv is unknown at the time of selection. Instead, the selection is based on the estimate Z v**derived from high density blast-hole samples within the deposit G. Nevertheless, the estimate Z v * of recoverable reserves in the stage of mine planning is derived from exploration data. At the end, the production result must be reconciled to the estimate Z v * . In other words, the selection is based on Z v** from blast-hole samples, while the final production figures are reconciled to Z v * from exploration drilling. For a given preselected cutoff grade z0, the actual mining panels will consist of the units having the estimated grade Z v** =z0 rather than the true grade Zv =z0. The difference between Z v** and Zv is usually of less concern."

Jan 1, 1998

By R. J. R. Schaller

NO. 3 winze, the sixth shaft to be sunk on the San Antonio property, is practically a duplicate of No. 3 shaft, which was the main shaft prior to the installation of the larger hoisting equipment in 1939. It is collared on the tenth, or 1,500-ft., level, and goes down vertically to the sixteenth, or 2,500-ft., level, with a loading pocket, spill pocket, and sump below this. It is 1,000 feet east of No. 3 shaft. All ore, men, and materials are handled through the latter. The winze location with reference to the rock formation is shown in Figure 1. (In plan, this section strikes N.30°E. and cuts most of the main orebodies of the mine normal to their strike.) It is collared eighty feet inside the footwall contact of the basalt and cuts through it before reaching the eleventh level. In this location there will be no ore tied up in shaft pillars, as the closest ore to the shaft is on the tenth level, and here it is eighty feet northeast of the collar. The winze headframe and hoist-room straddle the main haulage to the No. 3 shaft, on the tenth level (see Figure 2). At no time during the excavation for the headframe and hoist-room was the general routine work of this haulage held up.

Jan 1, 1941

By M. Fall

The progressive depletion of ore available at shallow depths in several underground mines around the world means that underground mining operations would increasingly be carried out at greater depths and therefore at higher temperatures. However, our understanding of the effect of hot temperatures on the response (mechanical, economical, environmental) of cemented paste backfill (CPB) is still limited. Hence, an extensive laboratory investigation was conducted to study the performance of young and aged CPB, in response to deep mine temperatures. Several CPB samples with different compositions, cured at different temperatures (20 to 50°C) and different times (7 to 160 days) were tested regarding their mechanical properties, economical performance (binder consumption) and microstructural properties. The results show that hot temperatures significantly affect the performance properties of CPB at young and advanced ages. An increase in the curing temperature leads to a considerable improvement of the rate of gain of CPB strength and also to a significant increase of the strength of CPBs studied. CBP samples cured at hot temperatures show lower binder consumption and finer pore structure. Results of this study could serve as background information for the development of optimal mine backfill design procedures.

May 1, 2007

By Leroy C. Stewart

Owing mainly to the use of ethylene dibromide in the production of tetraethyl lead for gasoline treatment, there has been a tremendous increase during the past decade in the demand for bromine. In the United States, production, derived mainly as a by-product from the treatment of brines from salt wells, rose steadily from about two million pounds in 1924 to nine million pounds in 1931. In 1936, production amounted to between 20 and 21 million pounds. Much of the increase during the past four or five years has been due to the operation of the Ethyl-Dow Chemical Company's plant, which extracts bromine directly from sea water. The process employed by the Ethyl-Dow Company is somewhat similar to that in use on salt-well brines at their plant at Midland, Michigan, but whereas these brines contain around 1,300 parts per million bromine, sea water contains only 65 to 70 p.p.m.-about as much as the waste effluent in the brine process. By intensive research, however, a process was developed whereby a very considerable percentage of the bromine content of sea water could be recovered, and at a satisfactory operating cost. In its essentials, the process consists in liberating the bromine from the sea water by treat-ment with chlorine, blowing the bromine out of the water by a current of air, and finally absorbing it in a solution of soda-ash.

Jan 1, 1938

By T. Motegi

Semisolid casting provides grain refinement of the cast structure and prevents macro-segregation. The conventional semisolid slurry is obtained by electromagnetic or mechanical stirring. In our process, the magnesium alloy (AZ31) slurry is made using an inclined cooling plate instead of the conventional methods. The slurry obtained is cast into a twin-roll caster and makes a continuous sheet of 2 or 3 mm thick. The most important factors that influence the sheet casting are the casting temperature and twin-roll speed.

Jan 1, 2007

By A. R. Farkoosh, K. Korgiopoulos, McGill University, O. Rodop, L. A. Villegas Armenta

"New generation of Al-Mg-Si alloys with thermally stable dispersoids that prevent recrystallization and grain growth during hot deformation are currently used in automotive components requiring good formability. Alloy chemistry controls the phase formation especially age-hardening precipitates, dispersoids, and primary intermetallic which have pronounced effect on grain structure, strength and formability. In this work, thermodynamic calculations have been used to predict the effects of varying levels of Si (0.5-1.5wt%), Mg (0.5-1.5wt%) and Mn (0.1-2.5wt%) on phase selection. Thermodynamic calculations have been performed in equilibrium and non-equilibrium conditions via the FactSage™ software using the FTlite database. Selected compositions have been cast, heat treated, extruded and characterized through scanning electron microscopy with energy dispersive spectroscopy and electron channeling contrast imaging techniques. The calculations showed that at the hot deformation temperature of ~540 oC, exceeding certain Mg and Si levels would lead to retained *-Mg2Si intermetallics and Si particles at the grain boundaries in addition to a-Al-(Mn,Fe)-Si. It was found that retained *-Mg2Si phase which adversely affects formability can be avoided for Si+2Mg levels lower than 2.3wt%. FactSage calculations also showed that increasing Mn from 0.5wt% to 1wt% leads to an increase in the amount of dispersoids (from 1wt% to 2wt%) that can potentially slow down recrystallization and grain growth during hot deformation and improve formability. Calculations at room temperature also show that for an alloy with 0.7wt% Mg, excess Si beyond 0.7 wt% promotes the precipitation of Si clusters in the Al matrix that accelerate natural age-hardening. Results were confirmed by experimental investigation.INTRODUCTIONAluminum alloy 6082 (Al-Mg-Si) is used in the automotive industry because of its high strength, and good weldability (I. J. Polmear, 2006). The alloy is age-hardenable through the precipitation of ß-Mg2Si and its precursors, and the recrystallization is usually inhibited by Mn- and Cr-containing dispersoids formed through high temperature heat treatments (I. Polmear & Couper, 1988). However, it is known that minor changes in alloy chemistry (Mg/Si ratio) can have significant influences on the ductility and formability of these alloys by altering phase selection and the resultant microstructure (Gupta, Lloyd, & Court, 2001; McQueen & Celliers, 1997; Zajac, Hutchinson, Johansson, & Gullman, 1994). For automotive applications where wrought alloys (usually extrusions) are cold-formed to produce suspension components, the chemistry of the alloys and the extruded structure are of crucial importance as they determine the formability at room temperature (Asensio-Lozano, Suárez-Peña, & Vander Voort, 2014). In this study, thermodynamic calculations along with experimental investigations were carried out on the Al-Mg-Si system to understand their phase formation and precipitation hardening as a function of alloy composition."

Jan 1, 2016

By R. D. Clarke, E. De Souza

"A framework for ventilation planning, with a focus on planning to the end-of-mine life, was developed for the Diavik Diamond Mine, Northwest Territories. This framework was successfully used by Diavik’s mine engineers to select a cost-effective ventilation plan that met the life-of-mine requirements. The framework achieved this result by reconciling the production plan with the ventilation plan. A set of design acceptability criteria was created and a PICK (possible, implement, challenge, kill) chart was used to quickly narrow down the generated ideas for detailed assessment and economic analysis. RÉSUMÉ Un cadre de planification de l’aérage, qui met notamment l’accent sur la planification jusqu’à la fin de vie de la mine, a été développé pour la mine de diamants Diavik. Les ingénieurs miniers de Diavik ont su mettre à profit ce cadre pour sélectionner un plan d’aérage rentable qui répondait aux exigences propres à la durée de vie de la mine. C’est en conciliant le plan de production et le plan d’aérage que cet objectif a pu être atteint. Un ensemble de critères d’acceptabilité de la conception a été créé et un tableau PICK (de l’anglais possible, implement, challenge, kill, une méthode donnant la priorité à certaines actions proposées ou à des idées visant à résoudre des problèmes) a été utilisé pour rapidement limiter les idées générées et les soumettre à une évaluation et une analyse économique détaillées.INTRODUCTION The Diavik Diamond Mine, Northwest Territories, has been an underground-only operation since 2012 and has a remaining mine life of 8 years. In the first year of underground-only operations, the production rate increased from 60 kt of ore per month to more than 160 kt of ore per month. In subsequent years, this rate was continuously increased (Table 1) because the operation went through various improvement initiatives. By the end of 2016, Diavik’s total production was 0.41 Mt (+22.8%) ahead of the 2012 budget for 2016 production."

Jan 1, 2018

By R. Howard

"In projects involving resource development and plant optimization, the use of in-mine geophysics can deliver considerable benefit. The value proposition lies in using very high resolution downhole measurements to model process-plant outcomes. The calibration procedure used to convert in-situ physical properties into process engineering parameters is illustrated using two iron ore projects. Data correction was related either to orebody structure or mineral formation. The deliverable from this approach is a series of high-definition sections indicating the variability of ore delivered to a front-end separation plant and parameters for mine scheduling and stockpile design needed for maximum product yield.RÉSUMÉ Dans des projets de développement des ressources et d’optimisation de l’usine, l’utilisation de la géophysique minière peut engendrer des bénéfices considérables. La valeur de la proposition réside dans l’utilisation de diagraphies à très haute résolution afin de modéliser les résultats de l’usine de traitement. La procédure d’étalonnage utilisée pour convertir les propriétés physiques in situ en des paramètres d’ingénierie de procédés est illustrée en se basant sur deux projets de minerai de fer. La correction des données porte sur la structure de la masse minérale ou de la formation minérale. Les livrable attendus de cette approche sont une série de sections à haute définition, signalant la variabilité du minerai livré à une usine de séparation de première ligne, des paramètres pour l’échéancier de la mine et la conception des haldes requis pour une production optimale."

Jan 1, 2016

By Andrew Dobson, Cheryl Allen, Enrique Acuña

"Totten Mine return air raise was designed with two parallel fans equipped with silencers to reduce the noise emitted from the outlets into the environment. As development and production of the mine progressed through the past years, the silencer system needed to be upgraded, and additional maintenance strategies have been necessary to meet the regulatory noise limits enforced by the province of Ontario. The current mine plan will require the fans to reach the upper limit of their capacity by Q1 2019. To achieve this operational target, additional silencing capability has been required and Totten Mine has explored alternatives to further extend the noise silencing capacity available considering the current constraints at the mine site. The alternatives included a new silencer baffle design and a new layout that have allowed doubling the length of the silencer system. Using acoustic measurement data collected on several occasions, this paper presents and discusses the performance of the various silencing systems which have been installed on the return air fans at Totten Mine.INTRODUCTION Vale Canada Limited’s Totten Mine is a base metal, underground mine extracting nickel and copper, situated in the Sudbury Basin of Ontario. The mine initiated operations at the end of 2013, and is equipped with two main return air fans and two main fresh air fans located on surface. Both fresh air and return air fans are set in a parallel arrangement to operate as integrated units and are equipped with variable frequency drives (VFDs) to allow for the remote modification of their operating set point, usually between 600 to 880 rpm, depending on the mine’s requirements. The main return air raise (RAR) fans are also equipped with dissipative baffle silencers to attenuate the noise emitted to the environment. Approximately four years ago, acoustical measurements conducted to verify compliance with the applicable regulatory criteria, and respond to noise concerns from neighboring residents, concluded that the sound emissions of the main return air raise exceeded the noise design parameters. The acoustic tones of the fans were audible offsite, at a residential location, approximately 9 km northeast of the mine site. The elevated sound levels and offsite audibility was due to degradation of the original discharge silencers from moisture and particulate being drawn from underground workings and passing through the silencer baffles. The audibility was also due to an outlet directivity pattern which directed noise towards the residential location."

Jan 1, 2019