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By Bernard Tougas, Franco Chiesa, David Levasseur, Bernard Duchesne

"In the present paper, the optimization of a tilt poured permanent mold will be carried out using filling and solidification modeling. This exercise resulted in 3 modifications of the initial mold design which was based on the foundry experience. The optimization provided a 20% improvement in the yield while increasing the output from 10 to 15 castings per hour.In a subsequent study, the value of the critical fraction solid of AlSi7Mg (A356) alloy was verified by radiographic analysis of the castings produced in the first 5 cycles of a run, which are necessary to bring the mold to a dynamic thermal equilibrium."

Jan 1, 2014

By A. W. Jacobs

SHORTLY after Denny, Robson, and Irwin(l) published their first paper, in 1937, on the prevention of silicosis by metallic aluminium, experiments were begun on the practical application of the discovery. It was thought at that time that aluminium powder, to be effective in aluminium therapy, would have to be intimately admixed with siliceous dust at the latter's source. There followed several years of experimental work underground, during which the application of aluminium powder was tested in: (1) Shakers on machine columns, vibrated? by drills (2) Vials placed in drill holes to be blasted (3) Both homogeneous and heterogeneous. mixture with explosives ( 4) Packages with tamping (5) Compressed-air lines (6) Special compressed-air ejectors for use while drilling and after blasting (7) The discharge of ventilation fans (8) The filters of respirators It was concluded from this research that any adequate method of introducing aluminium powder into a mine atmosphere would require too much extra gear, supervision, and aluminium powder, and would interfere unduly with underground routine. Later, animal experiments by Denny, Robson, and Irwin(2) showed that aluminium powder provided effective therapy when inhaled independent of silica dust. Therefore, some means of surface treatment was deemed more practical.

Jan 1, 1944

By W. A. Jones

THE Ross mine, a subsidiary operation of Hollinger Consolidated Gold Mines, Limited, is situated near the north end of lot 1, concession 2, Hislop township, Ontario. The property comprises the north half of lot 1, concession 2, and the south one-third of lot 1, concession 3. It is readily reached by a good motor road from the village of Ramore, 7.5 miles to the southeast on the Temiskaming and Northern Ontario railway. The-mine has been developed to a depth of 900 feet and the current daily production rate is about 260 tons. From the inception of operations in March, 1935, until December 31st, 1942, 455,720 tons of ore with a total value of $4,169,-316 have been milled. The silver to gold ratio of 1.48 to 1 is unusually high for Ontario gold mines. The deposit is interesting because the relationship between hydrothermal metamorphism and three successive stages of fracturing and mineralization is marked with considerable clarity. During the past seven years, detailed geological maps of the mine have been kept up to date, many thousands of feet of diamond-drill core have been logged, and numerous thin and polished ore sections have been studied. The present paper describes the structure and mineralogy of the orebodies.

Jan 1, 1944

By P. Woo, N. Brodusch, R. Gauvin, H. Demers

The scanning electron microscope (SEM) was primary developed for imaging applications. With the introduction of the Si(Li) energy dispersive spectrometer (EDS), simultaneous imaging and x-ray microanalysis became possible. However, long working distance and high current were needed because the position and small solid angle of the EDS detector. The high spatial resolution is generally obtained at short working distance with a SEM. Unfortunately x-ray microanalysis is never performed in the best imaging conditions. The annular silicon drift detector system is inserted below the objective lens which gives a higher solid angle (up to 1.3 sr). In consequence, a lower working distance and probe current can be used. An improved spatial resolution becomes possible during x-ray microanalysis. With this x-ray detector installed on a cold-field emission scanning electron microscope, quantitative x-ray microanalysis with high spatial resolution at low beam energy and low current becomes possible with the possibility of using the various different type of imaging at the same time. Also, since the count rate can be as high as 1,500 kcps, which lowers significantly the detection limit of elements as well as the minimum feature sizes of different phases that can be distinguished.

Jan 1, 2014

By K. J. Aglias, M. Jeffery, J. V. Simmons, J. A. Johnston, S. G. Fityus

"Shales and mudrocks undergo weathering in the near-surface geological environment, and degradation when directly exposed at the surface. Despite having superficially similar appearances, many shales have very different degradation behaviours. For example, some shales break down readily upon exposure whilst others remain more or less intact. Further, for those shales which break down, the style of degradation can vary greatly. A phenomenon is described where fresh shale blocks that are exposed at the surface undergo rapid breakdown to a fragmented texture which then persists for relatively long times, without further breakdown to finer soil particles. This is illustrated for some coal mine waste rocks. Furthermore, this metastable fragmented texture seems to be particular to each particular type of shale. The paper presents a conceptual model for this physical breakdown of shales which accounts for the differences in fragmental texture that are observed. The importance of several factors including strength, permeability and expansive clay content are identified for their contribution to the degradation behaviour of different shales.INTRODUCTIONShales and MudrocksThe term shale is applied widely to a class of mudrocks having a range of distinctive but gradational appearances and mechanical behaviours. Mudrocks are sedimentary rocks primarily composed of silt and clay sized particles (Tucker 1982). Mudrocks form in low to very low energy environments such as flood plains, lakes and deltaic environments, where the finest detrital particles are able to settle out of suspension (Reeves et al., 2006; Stow, 2005; Tucker, 2001).Unlike coarser siliciclastic sedimentary rocks, mudrocks do not present with a wide variety of sedimentary structures and textures. The most common texture is a preferred orientation of clays and micas parallel to the bedding plane. This textural component is related to the property of fissility or the ability for such textured mudrocks to split along smooth planes that are parallel to the bedding. Another common structure is lamination, formed by variations of grain sizes and types during deposition, Massive texture describes the situation where no sedimentary structures or textures are apparent (Boggs Jr., 2009; Tucker, 2001). The term shale varies between sources and contexts, with Reeves et al. (2006) stating that a shale is a fissile mudrock, where “fissility is a property that has developed at a certain stage of weathering”."

Jan 1, 2015

By J. K. Van Beek

The Deep Underground Science and Engineering Laboratory (DUSEL) is a scientific facility that will be placed in the deeper reaches of the Homestake mine, Lead, SD. Our team of geologists and engineers is carrying out the first scientific project awarded to the site ? Towards a Transparent Earth. Taking advantage of the thousands of open exploratory and sand-line holes, we are installing the beginnings of a seismic observatory. Each installed station consists of a 3-D accelerometer package and a 1 nanoradian 2-D tilt meter. In order to allow for a variety of monitoring and characterization studies, the array instruments are sensitive over the frequency bandwidth of 0.2 - 1 KHz. Three, three component accelerometer stations are currently installed ? in a 140 m deep bore beneath the slurry pump house, and in 12 m deep bores on the 2000-foot level, 800 and 400 m from the Ross shaft. There is a tilt-meter installed at each 2000 level station. These installations are in 150 mm diameter sand-holes. From the currently installed tilt sensors we are investigating solid earth deformation as a response to tidal potential. The accelerometers are being used to locate and characterize events associated with mine dewatering and rehabilitation.

May 1, 2009

By J. F. Nie

Mechanical properties of precipitation hardenable magnesium alloys depend critically on the chemistry, structure, morphology, orientation and distribution of strengthening precipitates. It is therefore important to gain an improved understanding of these information and their correlations with mechanical properties. Our recent studies indicate that additions of 1-2 wt% of Zn to a Mg-6wt%Gd alloy result in a substantial enhancement in precipitation hardening and in creep resistance. If the strength and creep resistance of the resulting ternary alloy are to be further enhanced for commercial applications, then a detailed characterisation of the strengthening precipitates in these alloys is required. In the present study, the precipitates formed in a Mg-6Gd-1Zn-0.6Zr (wt%) alloy, peaked aged at 250°C, have been characterised in detail using transmission electron microscopy and 3-dimensional atom probe field-ion microscopy. It is found the peak-aged microstructure contains a dense and uniform distribution of precipitate plates that form on the basal plane of the matrix phase and are typically less than 1 nm in thickness. Detailed analyses of the structure and composition of these basal precipitate plates will be presented and discussed in the context of previous work on other Mg-RE¬Zn alloys of similar compositions.

Jan 1, 2006

By A. Jeffkins

Visibility is restricted when operating load haul dump vehicles resulting in a number of serious accidents in the Ontario Mining Industry. One of the leading causes of these accidents is the inability of the equipment operator to see clearly people, objects or hazards around the machine. Previous line of sight testing by the research team found specific machine characteristics were responsible for blind spots and impaired visibility. In order to identify feasible design modifications a computer simulation program, Classic JACK 3.1, was utilized. Program features include human factors analysis, which allows evaluation of line of sight and operator posture in order to decrease risk of musculoskeletal injury. Research within the virtual computer environment consisted of a Visibility Audit and a Target Audit in order to quantitatively determine how certain components of the LHD design affected the line of sight around the vehicle. Results indicate that modifying the LHD light brackets, engine profile, cab posts and other components will enhance visibility. The addition of cameras located on the front and rear of the vehicle were able to enhance the operator?s sight lines to previously obstructed areas. Modifications to seat height and the operators orientation both improved sightlines and decreased risk factors associated with back and neck musculoskeletal disorders.

May 1, 2003

By Yue hua Hu, Wei Sun, Pan Chen, Li Wang, Runqing Liu, Central South University

"The flotation separation of muscovite from quartz was investigated using mixed sodium oleate/dodecylamine (NaOL/DDA) collectors. The flotation experiments were conducted on single minerals and their collecting performances were studied by means of adsorption amounts and molecular dynamics simulation. Flotation results show that muscovite presents good floatability while quartz exhibits poor floatability in alkaline condition. Adsorption amounts show that both NaOL and DDA can absorb onto surfaces of muscovite and quartz in presence of mixed surfactants. Molecular dynamics simulation indicates that DDA plays an important role in the adsorption of mixed surfactants on these two mineral surfaces. The molecules of mixed NaOL/DDA are arranged in a rigid and well-ordered packing on muscovite (001) surface. Only a few DDA adsorb on quartz directly, and rest DDA and NaOL molecule exist near by the quartz surface, forming a hydrophilic cylinder-like structure. This study may provide guidance for the flotation mechanism and application of mixed anionic/cationic collectors.INTRODUCTIONIn the past decades, there has been an ever-increasing demand for muscovite (KAl2(Si3Al)O10(OH)2) because of its potential applications in cosmetics, construction and metallurgy industries (Barlow & Manning, 1999). Besides, muscovite is an important carrier for some rare metals, including vanadium, titanium and lithium (SsuerrN, 1979). Quartz (SiO2) occurs as the main gangue mineral in muscovite ores, which results in a low purity of muscovite and limits its wide applications. Therefore, there is an urgent need for the beneficiation of low grade muscovite ores. Many studies remove quartz by screening and gravity separation in virtue of their differences in shape, hardness and density. However, these methods undergo poor efficiency in case of small particle size (below 50µm) of muscovite and quartz (Liubakka, Sullivan, Lamphere, Corradi, & Dykhuis, 2011; Santos, Franca, & Ogasawara, 2011)."

Jan 1, 2016

By V. Caps

Gold has been often used as an alloying component in order to increase or modify the catalytic properties of an active metal. For example, in the hydroconversion of methylcyclopentane, Riahi et al [1] shown that the addition of gold to palladium or platinum enhances the activity which becomes greater than that of the pure metals whereas the selectivity towards products resulting from ring expansion increases. Molenbroek et al [2] presented a detailed study on Ni-Au catalysts which exhibit activity for steam reforming and have been proved to be more resistant toward carbon formation than the pure Ni catalysts. Blocking of highly reactive Ni edge and kink sites by Au atoms is assumed to be the reason for the increased robustness of the Ni-Au catalyst. Nevertheless, the own catalytic properties of pure gold have been almost ignored up to the pioneering work of Haruta et al [3] which demonstrates the high activity of gold for CO oxidation at low temperatures. Other reactions such as WGS reaction, propylene epoxidation or benzene total oxidation have then been shown to be catalyzed by gold [4]. This discovery induced the publication of papers devoted to analyze the different factors controlling the activity of gold catalysts. Among them the most relevant appears to be the gold particle size, the nature of the support [5] and the preparation methods [6]. Clearly distinguish between support and size effect is not straightforward. Indeed, the calcination step often needed to synthesize supported catalysts on different supports, leads to different particle sizes showing that particle size and support are interdependent. To circumvent this difficulty, Au-based supported catalysts have been synthesized by using laser vaporization and low energy cluster beam deposition. The as prepared catalysts have then been characterized and tested in CO oxidation reaction.

Oct 1, 2003

By A. J. Sinclair

"Abstract-Geology contributes essential information toward obtaining high-quality resource/reserve estimates. In this context, geology can be considered under the following overlapping topics: regional geology, detailed (deposit) geology, mineralogy, ore deposit models and continuity, with geological mapping being fundamental to all. Each of these topics is considered here in terms of potential contributions to "improved" mineral inventory estimation. Some of the principal conclusions are:1. Regional geological relations must be consistent with deposit geology. It is common that important geological relations are more clearly evident in various regional locales than in highly altered and/or highly deformed mineralized areas containing mineral deposit.2. Detailed geology provides information for a geometric model of a deposit, a model that serves as a basis for mine planning. It is important to distinguish fact from interpretation in such models. Substantial effort is required to characterize the geometric margins of a deposit and the relation of these margins to the simplistic geometric form that normally emerges as an interpretation.3. Mineralogical studies relate to many aspects of deposit evaluation including abundance of ore and deleterious minerals, spatial distribution of ore and deleterious minerals, grain size characteristics of important minerals, mill design, etc.4. Ore deposit models contribute substantially to confidence in developing a three-dimensional geometric model of a deposit for mine planning. Specifically, they are a basis on which to develop rules for interpolation and extrapolation of ore, and they contribute to recognition of domains, each with its own characteristic continuity and margin character.5. Continuity is dependent on mineralization style and may be controlled structurally and/or chemically. It is important to distinguish geological continuity and value continuity. A wide range of classical geological methods are useful in examining geological continuity; value continuity is best viewed as a statistical characteristic that is quantified by any of several measures of autocorrelation."

Jan 1, 1998

By Jerry Z. Lu

Belt conveyor design involves the evaluation of belt tensions, drive selection, pulley configuration and other technical issues. The conveyor belt tensions vary with conveyor layout, drive pulley configuration, belt selection, and idler selection. The decisions for the belt conveyor construction always take all technical, commercial and maintenance issues into consideration. A good conveyor design shall provide required operational features and at the same time be cost effective. The common issues for an engineer to face during belt conveyor design include: (1) Conveyor drive selection ? drive with fluid couplings or variable frequency drives; (2) Drive system configurations - single pulley large drives or dual pulley smaller drives, if intermediate tripper booster drives shall be applied, what power ratio should be adopted for a multi-drive conveyor; (3) Gear reducers ? shaft mount drives, right angle gear reducers or parallel gear reducers; (4) Drive pulley lagging - ceramic lagging or rubber lagging; If ceramic lagging, what type should be used. (5) Conveyor speed variation ? If conveyors run at variable speeds, faster speed/lower percentage loading or slower speed/higher percentage loading. In many cases the decision maker find themselves in a dilemma ? technical benefits vs. financial benefits, capital cost vs. operational cost, and capital and operational cost vs. maintenance effort. Although many conveyor design topics above have been discussed in numerous technical papers and design reference books, management executives and inexperienced engineers may be confused and feel lost. The consultation of people around them may lead to different opinions since experiences tend to vary, making the decision making process complicated. The purpose of this paper is to simplify these complicated issues and provide useful guidelines for belt conveyor design. This paper focuses more on providing simple and practical answers and solutions instead of discussing each topic academically and theoretically in depth.

Nov 1, 2011

By T. R. Bieler

"Hot forming and superplasticity in powder metallurgy aluminum alloys and composites is reviewed. The effects of alloy composition, particulate composition, size, and size distribution is summarized. The role of climb distance for recovery is described in connection with the size of strengthening phases. In materials with fine strengthening phases on the order of one micron or less, high strain rate superplastic deformation processes are likely. However, the quality of superplastic deformation depends on the prior processing history, and these effects are reviewed. Very few data describing the effects of hot forming history on post-forming properties exist, but some results emerging in the literature are compared.IntroductionHot deformation in aluminum based materials is done for several technological purposes, such as thermomechanical processing to alter mechanical properties of simple forms, and/or final shaping operations to produce a complex shaped part by means of extrusion, forging, or superplastic forming. In the interest of improving the mechanical properties of aluminum based materials, two microstructural design strategies are commonly used, dispersion strengthening, and composite strengthening. The introduction of fine, stable dispersions is commonly done for high temperature strength, and the dispersions are typically ceramic particles in the range of 10 nm to 1000 nm in volume fractions around 5 vol.% (Higashi et al., 1990; 1991a; 1991b; 1992; Bieler and Mukherjee, 1990; Otsuka et al., 1987; Bieler et al., 1991; Oliver and Nix, 1982). Alternatively, composite strengthening strategies using 10-40 v% of 3 µm to 40 µm ceramic particles provide high modulus and high strength aluminum based materials (Midling and Grong, 1995; Lloyd, 1994; Subramanian et al., 1995)."

Jan 1, 1997

By Francisca San Martin, Tomas Vargas, Willy Kracht

"In Cu-Mo deposits it is usual to find considerable amounts of pyrite (FeS2). When processing this kind of ore by flotation, pyrite is rejected using lime to increase the pH to alkaline conditions (pH ~10.5). In the case of using seawater without pre-processing, i.e., raw seawater, the lime consumption increases dramatically and the recovery of molybdenite drops due to the precipitation of magnesium hydroxide on its surface. In order to avoid these negative effects, alternative ways of depressing pyrite should be considered.The current work introduces the use of Acidithiobacillus ferrooxidans, bacteria commonly used in bioleaching, as an alternative to depress pyrite in seawater flotation. The paper presents the results of biodepression in three systems: fresh water, water with added sodium chloride at 35 g/L (which corresponds to the salt concentration in seawater ) and seawater. The results show that it is possible to bio-depress pyrite with A. ferrooxidans in natural seawater pH (7.8-8.2). A similar behaviour is observed when running the experiments in fresh water, and in water with sodium chloride added.INTRODUCTIONWater is a scarce but essential resource for human development. The main reason for this scarcity is that, although 70% of the earth's surface is covered with water, only 3% of the total is fresh water and an important part of this water is frozen, so that only 1% of fresh surface water can be used for human activities. In Chile, most of the mining activity is concentrated in the north of the country, located in the Atacama Desert, considered the world's driest desert. That is why some mining companies have chosen to use seawater in their processes. For example, Esperanza (Antofagasta Minerals), and Sierra Gorda (KGHM International) use raw seawater in their flotation processes."

Jan 1, 2016

"These guidelines have been prepared to assist the Qualified Person(s)in the planning and supervision of exploration programs which will be reported under National Instrument 43101. The Companion Policy of NI43101 references the guidelines and states that issuers and Qualified Persons should follow them.Exploration Best Practices GuidelinesPreamble: These guidelines have been prepared to assist the Qualified Person(s) in the planning and supervision of exploration programs which will be reported under National Instrument 43-101. Such exploration programs must be under the supervision of the Qualified Person who will be responsible and accountable for the planning, execution and interpretation of all exploration activity as well as the implementation of quality assurance programs and reporting. These guidelines are also recommended for use in the planning and execution of exploration programs which will not be reported under NI 43-101. This set of broad guidelines or ""best practices"" has been drawn up to ensure a consistently high quality of work that will maintain public confidence and assist securities regulators. The guidelines are not intended to inhibit the original thinking or application of new approaches, that are fundamental to successful mineral exploration.Results should be summarized and reported in a Technical Report of good professional quality in accordance with the National Instrument 43-101 and Form 1 contained in that instrument. All exploration work from which public reporting will ensue must be designed and carried out under the supervision of a Qualified Person (""QP""). A QP is defined in National Instrument 43-101 as an individual who is an engineer or geoscientist with at least five (5) years' experience in mineral exploration, mine development, mine operation or project assessment, has experience relevant to the subject matter of the project or report and is a member in good standing of a recognized professional association."

Jan 1, 2003

By Henry Hengeveld

Are the IPCC results credible? The most recent IPCC assessment is??an admirable summary of research activities in climate science? US National Academy of Science 2001 report to President Bush Joint statement by Academies of Science from 17 other countries ? May 2001 ?The work of the?IPCC represents the consensus of the international science community on climate change science. We recognize IPCC as the world?s most reliable source of information?and endorse its method of achieving this consensus.?

Nov 1, 2002

NANA Accepts Mining ­ 1974 - Leadership presented mining option to people ­ Community meetings; recognized need for cash economy ­ 1979 - Poll shows consensus in favor of mine development ­ 1980 - Shareholders approve mining; Congress approved land selections

May 1, 2002

By R. W. Thompkins

"PREFACEPart 1 of this paper, published in the September issue, covered the occurrence of uranium, radiation from uranium ores, the uranium series, radioactive theory, radioactive equilibrium and application to the radon series, the working level, the theory of emanation and diffusion, transport by thermal diffusion of radon emanating from porous rocks, and definitions.The October issue carried Part 2, which dealt with radiation theory applied to uranium ores, other radon migration factors, factors affecting the radon gas release rate, the measurement of radon gas emanation rates, the tunnel concept, variation of emanation rate with grade and estimating radioactivity from grade analysis.Part 3, in this issue, concludes the series by discussing the techniques for controlling radiation and providing some example calculations.17.0. Techniques for Controlling Radiation17.1. Altering the Factors In the Diffusion EquationIt has been noted that radon gas emanates from the surfaces of exposed ore to the mine atmosphere. The diffusion laws establish the rate of this flow. The fundamental relationship is that the rate of flow (J) is a function of the pore concentration and the distance from the surface. It is expressed as: []If any of these terms is varied, either naturally or artificially, the rate of gas emanation will be altered.Altering the Diffusion CoefficientThe literature describes many ways to lower the radon gas emanation rates which are dependent on changing the diffusion coefficient:1. A layer of ice on top of a tailings dam or on a soil.2. Humid clayey materials and swamped soils over a radon source."

Jan 1, 1982

Cambior has been involved in the Guiana Shield since 1990, first in Guyana and then in Suriname starting in 1994. This paper presents the history of Omai Gold Mines Limited in Guyana, where commercial production started in 1993 after an investment of US $150 million. In 1995, the mine was expanded in order to increase the milling capacity to 21,000 tonnes per day. After ten years of production, approximately 3 million ounces of gold have been produced. Building on this experience, Cambior became involved in Suriname with the Rosebel Project. A US $95 million pre-production program started in the fourth quarter of 2002, and the mine should be in commercial production early in 2004.

May 1, 2003

By G. C. Laurence

"This paper discusses the hazards and extensive precautions taken in Canadian uranium mines, concentrating plants and processing plants. It also outlines Canadian policy regarding the control of the sale and distribution of uranium and other nuclear materials.OVER THIRTY YEARS AGO, I spoke to The Canadian Institute of Mining and Metallurgy here in Montreal about radioactivity and its dangers. I must have made quite an impression thirty odd years ago, because now you have asked me to do it again. Of course, the picture has changed. Then they were mining uranium ore, recovering the radium from it and throwing away the uranium. Now they are still mining uranium ore, but are throwing the radium out on the tailings dumps. Thirty years ago, most people did not know what ""radioactivity"" meant. Nowadays, they have beard that it is dangerous, and some of them, recently, be-came worried about the radium in the tailings dumps and what becomes of it."

Jan 1, 1969