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By Oleg G. Tovmachenko

We have studied optical properties of fluorescent nanoparticles. These particles consist of a metal (gold/silver) core, an empty and a dye labelled silica shells. The different dye molecules with moderate quantum yields (about 0.3) has been used. Almost all of types of nanoparticles show fluorescence enhancement. This enhancement is strongly dependent on the degree of the overlap between the surface plasmon band of the metal and the absorption/emission band of the dye molecules. The results are interpreted in terms of competition between local field enhancement and quenching of fluorescence by the metal surface.

Oct 1, 2003

By Julian V. Simela

Conventional methods of underground surveying use theodolites/total stations and 3D laser scanners to obtain information about the underground environment. Current methods of geo-referencing these instruments to a mine reference system include triangulation, trilateration and resection. However, despite technological advancements, surveying procedures have remained slow, laborious and relatively unchanged during the last half-century. Recent innovations in the robotics community have shown that automated mapping of underground mining tunnels can be undertaken using 2D/3D laser scanners. These techniques have the potential to, in turn, improve upon current underground surveying and mapping methods. Automating surveying and mapping using current surveying tools without changing the setting up procedures or removing current constraints, or even changing the type of equipment used, does not change the status quo. The problem of moving from a static, tripod based surveying and mapping system to an unconstrained mobile surveying and mapping system is the subject of this paper. A current challenge for automated mapping is the ability to automatically geo-reference a mobile mapping system to a mine reference system. For a mobile mapping system that uses a horizontally mounted 2D laser scanner to gather data of the underground environment, the challenge of determining its position and orientation within the mine environment is magnified even more. This paper introduces Mobile Automated Scanner Triangulateration (MAST), a technique under development at Queen?s that is designed to geo-reference a mobile mapping system to a mine reference system for the purposes of underground mine surveying. MAST quickly and automatically determines scanner 2D position and orientation (azimuth) in a mine reference frame by using minimal human input.

Aug 1, 2013

By E. M. Stiles

Introduction The papers that follow deal with recently completed major improvements in practices at the Sullivan operations in Kimberley. The papers have been prepared by members of the Consolidated Engineering Staff and outline the construction programme which has been in progress for the past three years, entailing an expenditure of some millions of dollars. Four major operational changes have been brought about in the mine and concentrator. They are: (1) A change in backfill procedure for filling stopes below the 3900 level. (2) A 12,000-ton,per-day sink-float plant at the concentrator. (3) A new haulage system from the mine to the concentrator. (4) A completely new crushing plant and ore storage facilities located underground. A brief outline of the background and history leading up to this overall project will be given to show how each started as an independent betterment and how they were finally co-ordinated into one major programme. The first of these, namely, the necessity for backfilling stopes below the 3900 level, was the most pressing problem. All filling to date bad been done above the 3900 level, where mining was carried on in an irregular pattern of open stoping. Stopes below the 3900 level were first opened in 1940 and are being worked on a regular pattern of panel sub-level open diamond drill stopes. The two areas are separated by a sill pillar traversing the entire length of the vein at the 3900 level elevation.

Jan 1, 1950

By Helen Shang, Jianjun He

In nickel and copper production, sulfur dioxide (SO2) is generated during mineral smelting. Emission of sulfur dioxide into the atmosphere causes serious health and environment issues. Sulfuric acid plants, which convert the harmful SO2 gas to commercially useful sulfuric acid product, ensures safe and environmentally sound smelter operations. The sulfuric acid plant is mainly composed of a SO2 to SO3 converter, a series of heat exchangers and SO3 absorption towers. The SO2 converter is crucial for minimizing SO2 emission in a smelter. In this paper, steady state and dynamic modelling are carried out for the converter using mole and energy conservations. Simulations are performed to investigate the effect of feed conditions on SO2 conversion. The developed model represents an important component for modelling the acid plant in a smelter and is expected to provide a fundamental tool for the future optimization and control development.

Jan 1, 2014

By C. R. Edwards, D. R. G. Watt

"Equity Silver Mines Ltd. a member of the Placer Development group of companies operates Canada's largest silver mine near Houston in north-central British Columbia. Initially, the silver-gold-copper flotation concentrate contained excessive levels of antimony and arsenic, so a leach process was installed to remove undesirable metals and provide improved smelter terms for the leached concentrate. The leach plant which has been fully described elsewhere (1, 2, 3), was forced by deteriorating process economics to shut down in April 1984. Equipment was mothballed and alternate uses sought.The Endako Mines Division of Placer Development Limited, located some 150 kilometres east of the Equity mine site, shut down its molybdenite mining and milling facilities in the spring of 1982. Endako has continued to produce molybdic oxide (molybdenum trioxide or MTO) via intermittent roaster runs, and also a high purity, lubricant grade molybdenum disulfide in the Ultrapure Plant. With the steel industry in the doldrums, molybdenum chemicals present an alternate and growing potential for molybdenum sales. In 1982 Placer Development began testing this market. Molybdenum chemicals were produced in the United States on a toll basis using Endako MTO as process feed. The transfer of this production to Canada was being considered when Equity's leach plant shut down, and it was noted that most of the equipment and skills necessary could be provided by the leach plant. See Figure 1.A careful investigation of process requirements was completed by engineering and production staff at Equity and Endako. A provisional capital and operating cost estimate was made, and it was decided to perform a test run during July 1984. There were strong reasons to proceed with this project. A positive cash flow was expected for both Endako and Equity. Endako would have product to continue to expand in the molybdenum chemicals market with the added selling point that now the complete production process would be under direct control of Placer Development companies. Equity would further benefit since a portion of the leach plant would continue in operation thus maintaining and exercising our hydrometallurgical engineering and operating skills. Finally, Equity would have a base from which to search out other processes adaptable to the idled leach plant equipment."

Jan 1, 1986

By A. S. H. Kabir, I-H. Jung, J. Su, S. Yue, M. Sanjari

The final mechanical properties of wrought magnesium alloys are mostly controlled by microstructure and crystallographic orientation or texture. In common magnesium alloys, grain coarsening occurs during annealing process and formation of undesirable basal texture cannot be changed markedly. The aim of this work is to investigate the effect of static precipitation on microstructure and texture evolution during annealing at 250 °C after warm rolling of Mg-Al-Sn alloy. Mg-3Al-3Sn (wt. %) alloy has been designed using thermodynamic modeling software, FactSageTM, based on forming target stable and incoherent Mg2Sn precipitate within the industrial deformation temperature range. Microstructures and precipitation were investigated by optical and scanning electron microscopes and macro-texture was measured by X-ray diffraction (XRD) techniques. It was found that static precipitates form in a large scale at the recrystallized grain boundaries and retards the grain growth during annealing. Slight weakening in basal texture was also observed during annealing.

Jan 1, 2014

By Roméo Roussin

"The yearly production from the Asbestos Hill pit is 1,550,000 tons of asbestos ore, with a yield varying between 18 and 20 % . The orebody was exposed at the top of a hill, and initial production started without having to remove any overburden. The projected ratio of barren rock to ore, based on the present orebody, was 2 to 1. However, as it was necessary to push back the upper benches, this ratio has changed to 3 to 1. The final pit will be 2,300 feet long by 1,000 feet at the longest and widest points. The final depth will be 680 ft. A pit slope stability study was carried out and an average wall angle of 60-70 degrees must be maintained. Preshearing of final pit limits will produce good wall stability. Permanent access ramps will be 60 ft wide, with an 8 % maximum grade. Geological conditions and the low rock temperature are the major causes of the operation's drilling and blasting problems."

Jan 1, 1976

Waste rock extracted from a mine is typically stored nearby on the surface. Such waste rock piles must be designed to ensure their geotechnical and geochemical stability during the mine operation and after closure. The optimal construction of a pile requires detailed planning. Deposition should involve benches of limited height to control the global slope angle, based on the long term factor of safety. It can also be advantageous to compact the top of each bench and to give the surface an outward inclination to control water flow by limiting infiltration and favoring lateral diversion. When part of the waste rock contains reactive minerals, it is also deemed necessary to use selective placement with the non-reactive portion to prevent direct exposure to natural conditions. The construction must be well documented, and include data from the monitoring program. These and related aspects are presented and discussed in the paper.

Aug 1, 2013

By Malcolm Scoble

School Values ?? Each other; ?? Students, & helping them develop intellectually, personally & professionally; ?? Freedom to pursue educational & research opportunities; ?? Home-work-life balance; ?? The geographic-business community in which we operate ; ?? The pursuit of excellence; ?? Our contribution to society; ?? Creativity & innovation; ?? Teamwork & collaboration; ?? Career development, achievement & reward.

May 1, 2008

By Yufeng Yao, Robert P. Lowell

Abstract - Conductive heat flow anomalies associated with hydrothermal sulfide mounds on the seafloor have been studied. Sulfide mounds tend to focus conductive heat flow because sulfide minerals have a greater thermal conductivity than country rock. The topography of the mound above the seafloor, however, leads to a reduction of heat flow, particularly near the center of the mound. Because the focusing effect is constant, whereas the topographic effect decreases with distance away from the center, the focusing effect dominates toward the edges of the mound. The magnitude of these effects depends upon the conductivity contrast and the height/radius aspect ratio of the mound. Conductive heat flow anomalies at sulfide mounds also result from fluid circulation within the edifice. For the active and relict mounds at the TAG hydrothermal field, which have an aspect ratio of approximately 0.3 and a conductivity contrast of 3, the heat flux through the center of the mound should be roughly 70% of the background heat flux. The maximum effect of heat flow focusing is to increase the heat flux by about 30% above background. By comparing these effects with conductive heat flow data at TAG, we find that advective processes dominate conductive heat flow at both the active and relict mounds. Advective circulation can also give rise to much larger lateral and vertical temperature gradients than would result from conduction alone.

Jan 1, 1999

By D. S. Salonine

Aluminum alloys are widely used in modern industry. Tubes and hollow shapes give great opportunities for structural purposes as well as fluid transport due to their stiffness and lightness, Extrusions on a mandrel or through a bridge die, that requires splitting of the billet with re-welding, produce hollow shapes with varied contours, fins and multiple cavities. Moving and stationary mandrels, mandrel lubrication, tooling for ribbed-tube heat exchangers, and for drilling pipes are considered. Bridge dies can be classified by the bridge position relative to the die face, by mandrel support structure, and by assembly type, The main parameters influencing the quality of the die-welded seams are considered, The difficulties of extruding various alloys through bridge dies are discussed in terms of metallurgical factors, Some approaches to the calculation of the stresses in a bridge are presented.

Jan 1, 2005

By Gonzalo Bernstein, David G. Meadows, German Naranjo, Edgardo Tapia

"During the last decade Antofagasta Minerals’ Los Pelambres Mine has dramatically increased its ore throughput following the fast initial phase ramp up through a series of planned incremental expansions. The original 85,000 mtpd, two SAG line plant was commissioned in 1999 and rapidly exceeded nameplate tonnage in only a few months. Following this, the inclusion of a pebble crushing circuit resulted in throughputs in excess of 114,000 mtpd and a recent, final third line SAG and ball mill addition have taken the plant to over 175,000 mtpd even with increasing ore hardness and changing ore feed characteristics. The progressive changes are described in this paper together with how the technical challenges have been met.INTRODUCTIONMinera Los Pelambres is a world class copper-molybdenum operation located in the Salamanca area in Chile, in region four, approximately 500 km north east of Santiago, the capital of Chile. In the late 1990s Antofagasta Minerals developed the Minera Los Pelambres project in Chile at an investment cost of approximately $1.3 billion USDs. The project construction was successfully led and completed by Bechtel Corporation in 1999 and within a matter of months the plant was already exceeding the nameplate capacity of 85,000 mtpd. In 2001 a pebble crushing circuit was added to raise the capacity to 114,000 mtpd. In the early part of 2003-2004, it was recognized that the hardness profile was changing with depth and that in order to maintain the plant capacity additional power would be needed in the SAG mills together with upgrading of the primary crusher. In conjunction with these changes a fifth ball mill and a second primary crusher station would also need to be installed. A further detailed engineering study and evaluation was initiated by Minera Los Pelambres. This was lead by Bechtel Corporation with major design contributions from FLSmidth and Siemens in order to establish the re-powering requirements for the SAG mills. These re-powering changes together with the inclusion of a pebble crushing circuit took the plant to up to 125,000 mtpd even with harder more competent ores. Finally in the last two years an additional grinding line has been added to take the capacity to consistently over 175,000 mtpd. The third line was installed in a record time of 256 days. A schematic of the current comminution circuit, discussed in this paper, is shown in Figure 2."

Jan 1, 2012

By R. Salimi

Tricalcium aluminate hexahydrate (TCA) is used as filter-aid for security filtration in the Bayer alumina process. TCA is typically produced on-site by mixing Bayer liquor with slaked lime. Specific properties are required from the TCA to ensure adequate filter throughput, lifetime and importantly effective reduction of solid/colloidal impurities from the solution. The effect of reaction time on morphology and particle size distribution of tricalcium aluminate was studied for a batch experiment at simulated process conditions. It was found that reaction time plays a critical role on the morphology, crystal structure (diameter and crystallinity) and particle size distribution. In the early stages of the reaction, nucleation dominates the crystallization process followed by growth dominated by agglomeration up to a mean particle size of 10 µm. The particle morphology shifted from an irregular shape to more spherical throughout the course of the reaction.

Jan 1, 2014

By V. I. Lakshmanan, I. G. McColl

"Heap leaching of gold ores in permafrost conditions is feasible provided certain criteria are met. These criteria include relatively short heap leach residence time and the availability of waste heat.This paper describes the conceptual design of such a system for a mining operation in the North West Territories of Canada. The design includes the concept of continuous countercurrent leaching in enclosed ore heaps.Indicative capital and operating costs are given.INTRODUCTIONIn April 1984, Acres Davy McKee Engineering Inc. (ADM Eng.) in association with Ontario Research Foundation (ORF), was invited to carry out a preliminary design, cost estimate and financial analysis to assess the viability of gold heap leaching in a permafrost region in North West Territories, Canada.An orebody was being explored which could, by nature of its mineralogy, be upgraded substantially by crushing and screening in the size range of 1/4 in. to 3/4 in. It was proposed to process the screen undersize through an existing gold mill on site and to treat the oversize material in a heap leach facility to be constructed adjacent to the existing mill.Despite the formidable challenges imposed by isolation, permafrost and harsh winter conditions, the heap leach project was considered worthy of examination because of the relatively high grade of the heap leach material (> 0.1 oz/ton), very short leach times (in the range of 1 to 4 days) and the availability of substantial quantities of waste heat from the diesel generating station on site.Design challenges included the necessity to maintain the permafrost in frozen condition, to prevent freezing of ore and leach solution, to limit size of construction materials to that which could be carried in a Hercules freight plane and to contain water usage at an absolute minimum level."

Jan 1, 1987

Productivity and efficiency of diesel-powered underground trucks and LHDs can be enhanced through the application of a range of advanced technologies. In addition, these machines are subject to ever more stringent emissions control requirements. This paper will review how various technologies can improve usability, maintainability, and performance of LHDs, through a number of examples. The use of instrumentation and monitoring to understand the role of operator practice on mucking efficiency, as well as the use of finite-element analysis to evaluate structural design, and the use of control techniques to modify operator inputs and hence decrease power consumption, will be presented.

May 1, 2002

By Cheowchan Leelasukseree

Mae Moh mine, operated by Electricity Generation Authority of Thailand (EGAT), is the largest open pit mine in Southeast Asia. Its production is approximately 15 million lignite tons and 90 million m3 of waste, annually. The bottom of the final pit limit is designed to be approximately 500 m in depth. Presently, the pit depth is almost 250 m below original surface. The complexity of geological structures, such as faults, has caused a number of geotechnical difficulties. In a challenging lowwall area, called Area 4.1, an inclined weak bedding plane, G1, will be daylighted along the lowwall as following by mine plans. The dimensions of Area 4.1 are nearly 300 m wide and 90 m high. The friction and dip angles of the G1 interface are reportedly 12° and 15°, respectively. A three million m3 claystone block, resting above G1, would potentially slide down, and possibly cause a massive failure. EGAT engineers are acutely aware of the potential gigantic sliding failure and are modifying the mine plan in Area 4.1 to improve mine safety and minimize the displacement of the potential sliding block, reduce the possibility of failure and lower the additional mining cost as much as possible. The cut and fill mining technique was selected and studied to achieve those goals for mining in Area 4.1. With this mining technique, G1 will be partially daylighted. Therefore, an arch formation is induced with a sliding block above the mining area, which could perform as a temporary support undercutting a certain span. Initial studies of the behavior of the partially undercut slope are presented in this paper, along with a review of the similar failure history in Mae Moh mine and a 3-dimensional numerical model of the mine. The failure history review provides an estimation of undercut span without failure. The three-dimensional numerical model results, using 3DEC, gave an initial approximation of the displacement of the sliding block in Area 4.1. The next exciting study of the behavior of partially undercut slope is a trial undercut slope field experiment in Area 4.1. Currently, a trial undercut slope field experiment in Area 4.1 is under construction. In the field experiment, a number of monitoring programs will be installed in Area 4.1 to monitor and obtain information to allow a better understanding of the behavior.

Jun 1, 2012

By Junhyun Choi, Allan Gomez-Flores, Chonbuk National University, Siyoung Q. Choi, Gahee Kim, Seungkon Kim

In this study, to confirm the effect of depletion attraction on the flotation, we theoretically and experimentally investigate the effect of the depletion attraction force on flotation. While varying the concentration of the depletion agent (polyethylene glycol), three different systems are studied: pure malachite, pure silica, and a 1:1 mass ratio of malachite and silica binary system. We find that recovery increases significantly as the concentration of the depletion agents increases for all three systems, as the depletion agent facilitates the adsorption of the particle on the bubble surface. However, the recovery suddenly decreases in a certain concentration range, which corresponds to the onset of the decreased surface tension when high concentrations of the depletion agent are used. This non-monotonic overall recovery trend implies the surface adsorption of the depletant on a surface. The decreased surface tension of the air/water interface suggests that the recovery rate is lowered due to the adsorption of the depletion agent to the bubble surface, acting as a polymer brush. Based on our observations, we conclude that the depletion force can greatly improve particle adsorption, as predicted in the accompanying theory paper, while simultaneously the adsorption of the depletion agent on the bubble surface plays an important role because it hinders particle adsorption. We also perform experiments in the presence of a small amount of a collector, sodium oleate. An extremely small amount of the collector leads to the increase in the overall recovery, which eventually reaches nearly 100 percent. Nevertheless, the grade worsens as the depletant provides the force to silica particles as well as target malachite particles.

Jan 1, 2016

By C. Cekerevac

The paper addresses some geotechnical issues related to the construction of the Deriner dam and HEPP. Design considerations and rock stabilization measures are presented for the excavations which took place in a highly fractured and weathered rock mass prevailing on site. Particularly, the shallow excavations for the overflow spillways tunnels are discussed. These present huge openings that are 12 m wide and 18 m high in portal areas, with an overburden of approximately 20 m, for which numerical finite element analysis and structural discontinuity analysis have been performed to ensure safe excavation process and future operation.

May 1, 2009

By J. A. Hillier

"IntroductionThe purpose of sampling is to remove a portion of material from a stream which is representative of it in size, moisture and mineral content.To prevent the effects of segregation, generally caused by the way in which a conveyor, pipe or launder is loaded or directed, the sampler should cut proportionally the entire cross section of the stream.If one conveyor transfers to another at a right angle, fines may be dropped on the near side, and the coarse material thrown to the opposite side. Segregation can also occur as a result of the motion of a conveyor belt passing over the idlers causing the coarse material to roll to the sides of the belt.When slurry changes direction of flow in a launder or pipe, the heavier and coarser fraction will centrifuge to the outside of the curve and tend to remain on one side of the stream. Similarly, if two streams joining in a common launder are not mixed at the point of confluence, they will continue down the launder unmixed . This effect is particularly noticeable in a plastic lined launder.Therefore, a proportional sample is usually accomplished by a constant rate of cutter travel across the entire stream, making certain that the cutter is not full or splashing over before reaching the end of travel.The cutter should operate on a constant interval based on time, tonnage and uniformity of flow. The opening should be at least three times the width of the largest piece to be sampled. The cutter width is more critical with ore samples where particle sizes are large. With slurry samples, the opening is usually much larger than the minimum in order to obtain sufficient samples"

Jan 1, 1989

By E. R. Landry

This paper reviews the current state of electric furnace technology, with emphasis on some of the more recent developments. A large section of the paper is devoted to the use of increasingly high power inputs by arc furnace operators. Operating practices are then covered, including some of the newer techniques which have been tried.

Jan 1, 1967