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By P. G. Roden, G. A. Maki, P. J. Fullmann

"In October 1984, Rocanville Division began using a stacking system to handle potash mill tailings. Previous to this date, mill tailings were slurried to the top of the tailings pile and allowed to debrine while flowing mobile stackers. The stackers consist of cyclone packs to debrine the tailings and drag conveyors with screw discharges to deposit the tailings onto the existing pile. The paper will deal with the various aspects of the project from conception to its present state. Key Words: stacking, mobile stackers, Linatex Separators, potash mill tailings, reclaim brine ponds, settling ponds, tailings pile. IntroductionPrevious to 1984, when the stacking project was first implemented, potash mill tailings were handled as follows. Mill tailings were first debrined to approximately 65% solids using a cyclone cluster. The cyclone underflows were then introduced onto a vacuum scroll filter table. Here the tailings were further debrined and discharged into the disposal tank where the tailings were reslurried with reclaim brine and pumped to the tailings disposal site. At the disposal site the slurry was discharged onto the tailings pile and by a natural settling process the tailings were debrined with the brine ultimately collected in the reclaim brine ponds. The shape and profile of the tailings pile was controlled by building salt dikes to control the flow of the discharged tailings slurry. As the tailings pile grew in height, booster pumps were added to the disposal system."

Jan 1, 1986

By Tom Olsen, Tom Ohrling, Peter Taggart, Chris Martin

"North American Palladium commissioned the new concentrator at the Lac des Iles mine in the summer of 2001. The 15,000 tonnes per day mill replaced the existing 2,400 tonnes per day facility, as part of a major mine expansion.At Lac des Iles, the grain size distribution of the platinum group minerals (PGM) is bi-modal. Roughly two-thirds of the PGM are relatively coarse-grained, and often associated with fast floating copper and nickel sulphides. The remainder is ultra-fine, and locked in silicates, which poses a special challenge to the metallurgist. The previous mill typically recovered just the fast-floating mineralisation, but to achieve target recoveries, the new mill has to recover a substantial amount of the ultra-fine PGM. The metallurgical challenges associated with the recovery of fine-grained PGM in the talcous Lac des Iles ores, are described.The paper describes the approach used in circuit optimisation, and how metallurgical and operational optimisation raised palladium recoveries by more than 6% in six months, by tuning the circuit to recover some of the ultra-fine PGM mineralisation.BACKGROUNDThe Lac des Iles mine, owned and operated by North American Palladium Limited, is located about 115 kilometres north of Thunder Bay, Ontario. The mine originally opened in December 1993, and prior to 2001 included a mill capable of handling 2,400 tonnes per day of ore delivered from the nearby Roby pit.Following an intensive exploration programme conducted in 1999, and a detailed feasibility study, conducted in 2000, North American Palladium initiated a mine expansion project, the objective being to expand milling throughput from 2,400 tonnes per day to 15,000 tonnes per day. This required construction of an entirely new mill, which was commissioned in May 2001."

Jan 1, 2003

By P. K. Naik, B. Das

Flotation studies were carried out to recover carbon values from blast furnace flue dust containing ~30.34% carbon, 4.6% volatile matter (VM), and 65.03% ash. The variables chosen for the experiments were dispersant (sodium hexametaphosphate), pH, collector (diesel oil), and frother (MIBC). The experiments were designed according to a 24 full factorial design method and regression equations for the recovery of carbon and product grade were determined from the data. Experiments were performed to optimize recovery and grade using the steepest ascent method. The maximum recovery of carbon was 90.0% with a concentration of 56.5%, whereas the maximum obtainable grade of carbon was 66.35% with 50.45% recovery.

Jan 1, 2005

By A-A. Bogno, Ch. -A. Gandin, A. Maitre, H. Henein

Most metallic materials are produced from their liquid state. In order to control the properties of industrial products, it is very important to understand their solidification path and the resulting microstructures which can be significantly affected by melt undercooling. High undercooling results in rapid solidification and a refined microstructure with minimal microsegregation. This paper reports on the analysis of rapidly solidified Al-Cu droplets obtained by a single fluid atomization process, Impulse Atomization. A quantitative analysis by Rietveld refinement method of the Neutrons Diffraction data was carried out to determine the fraction of the intermetallic Al2Cu. Knowing the fraction of Al2Cu, the eutectic fractions and corresponding dendritic and eutectic undercoolings were estimated using the metastable extensions of solidus and liquidus lines of the Al-Cu system calculated by Thermo-Calc. In addition to this work, a model of microsegregation coupled with ThermoCalc software via TQ (application programming interface of ThermoCalc) and the Wang-Beckerman model for dendritic growth velocities has been developed for binary alloys. This has led to the development of a phenomenological relationship between primary phase undercooling and initial growth velocity. A comparison of estimated primary undercoolings using a coarsening model with the adiabatic undercoolings for each alloy composition has confirmed that solidification occurs under adiabatic conditions during recalescence.

Jan 1, 2014

By A. Vasenev

The quality and durability of asphalted roads strongly depends on the final step in the road construction process; the profiling and compaction of the fresh spread asphalt. During compaction machine operators continuously make decisions on how to proceed with the compaction accounting for project specific aspects as: ambient conditions, road geometry, roller type, asphalt mixture characteristics and behavior of other machines. In discussions over quality improvement in road construction it is often suggested to robotize rollers. To operate such robots would of course require operational strategies and routines. The reality of this moment is that these operational strategies and routines are not documented. To identify the existing best working practices and, ultimately, to proceed with developing automated robotized compactors, the knowledge of machine operators should at first be explored and described in a formalized way. Unfortunately operators have difficulty verbalizing their expertise. Observation of behavior, as machine movement patterns, could be helpful to extract the operational strategies, but such observations are time and labor consuming. To overcome this burden we developed a Virtual Reality (VR) environment. In this VR environment operators perform compaction virtually, and their operational choices are traced and analysed. This paper describes this VR development and explains how it helps in following machine operators and extracting their (tacit) professional knowledge. The road geometry and the working conditions are visually represented; the operators show - rather than explain - how they would proceed with the compaction process in the given conditions. Movements of virtual machines are documented, analysed, visualised and discussed. This VR approach is expected to contribute to learning, to more formal description of operational strategies; stepping stones towards compaction algorithms for roller robotisation.

Aug 1, 2013

The Stability Graph Method is widely used in Canadian underground hard rock mines for open stope support design and is frequently used in the mine planning phase to assess the viability of stope geometries and to determine maximum permissible spans. The Method is well accepted due to its simplicity and suitability to a wide range of mining methods requiring the use of sublevels to access and extract the mining blocks. While this Method is reliable in situations where the maximum induced tangential stress creates adequate compressive stress keeping the face in a state of confinement, the Method fails to reflect the effect of low confinement caused by lower compressive stresses and instances where tensile stresses are developed. In this paper, a new Rock Stress Factor, A?, an update to the original Rock Stress Factor, A, is proposed, which will reflect the impact of low confinement or overstress regime on critical face stability. Two case studies, based on two Canadian operating gold mine shows that using the new Rock Stress Factor A? to predict the stability of stope hanging-wall and footwall gives better agreement with the CMS survey results, compared with the prediction using the original rock stress factor.

May 1, 2011

By L. H. Shang

The 319 Al-Si alloy is one of the most prominently used aluminium-based alloys in motor vehicle and engine applications, Microporosity present in 319 alloy castings reduces the load bearing capacity of the castings, The quantitative prediction of microporosity levels in Al-Si castings has been a subject of much interest for several years. In this research a new criteria function, tf 1,98 R13° (tf: local solidification time, R: cooling rate) was developed by multiple regression analyses, correlating thermal data from simulation studies to experimentally obtained microporosity values. This new criteria function gives a general prediction of microporosity in 319 Al-Si castings.

Jan 1, 2005

By J. Y. Hascoet, M. Marya, S. Marya

Additive manufacturing (AM) brings disruptive changes over the ways parts and products are designed, tested, qualified, assembled, inspected and marketed. With these changes come real technical challenges, therefore, concerns that mainly stem from the maturity and diversity of today’s AM processes, the feedstock materials, and the interactions between the numerous process parameters. Additive manufacturing is somewhat similar to laser and electron-beam conduction-mode welding and involves a multitude of dynamic physical events between projected feedstock and moving heat source that influence process robustness, thus deposit properties. For this paper, a simple air vent, selected for its size, thin-wall, hollow geometry and materials (specifically 316L) was made using a laser-based powder blown technology (Construction Laser Additive Direct or CLAD) and systematically inspected by optical microscopy, microhardness indentations, and electron-back-scattering diffraction (EBSD). This exemplary part is first analyzed to broadly discuss metallurgical phenomena in additive manufacturing, particularly solidification and texture development. The paper then expands to other alloys and continues correlating metallurgical observations to process parameters and part properties, also borrowing from past experience with the same 3D printing CLAD system.

Jan 1, 2014

By Hugo Julien

According to OSHA 29 CFR Part 1910.119 (Process safety management of highly hazardous chemicals), Canadian Provincial Safety Standard Acts or Federal laws, the owner of stationary equipment (Boilers, stacks, piping, pressure vessel, etc.) should follow a complete inspection plan and follow an Integrity Operating Windows (IOW’s) adapted for each of them. Some important variables shall be included in the inspection plan such as specific damage mechanisms versus alloy used in the original design, process conditions, etc. Some North American’s standards exist, like the one listed in ASME PTB-2-2009, to help owner to create such inspection program. The new API RP 584, Integrity Operating Windows (IOW’s) can guide Mining & Metals owners to find out their specific IOW’s. Inspection frequencies are often described in the Jurisdiction Safety Acts such as the British Columbia B.C. Reg. 104/2004, etc. but often left in the owner representative responsibility (Bill C-21, federal Act to amend the Canadian Human Rights Act). Every deficiency should be repaired according to recognized Codes such as ASME PCC-2, etc.. If flaws not conforming to the original Code of construction are found, this article will introduce the Fitness-For- Service assessment principles to be able to accept it without any repairs.

Jan 1, 2014

By Ian Holl, Adam Hempstock, Rickardo Welyhorsky, Niel Morrison

"The Victor Diamond Mine is located in the James Bay lowlands, 90 km west of the First Nations village of Attawapiskat. The project was the first of its kind in northern Ontario and was completed approximately 9 months ahead of schedule.The Victor Mine process plant flowsheet was designed to produce a 95 - 98% by weight diamond concentrate. Main processing steps include 3 stages of comminution, dense medium separation and proprietary x-ray technology for final recovery. Reagent consumption for this process is limited to flocculant, for thickening of fine processed kimberlite, and FeSi for the dense medium separation.The commissioning phase of the Victor Project was executed over a period of 6 months and commenced prior to substantial completion of construction. The approach used was to focus on and complete commissioning of the higher risk dense medium separation and recovery systems prior to construction completion of up stream systems.INTRODUCTIONThe development of the Victor Diamond Mine took place over a period of approximately 5 years and had a capital cost of CAD997 million. It was a greenfields project in an undeveloped region of northern Ontario, only accessible by winter road. Figure 1, below, displays the location of the project within Ontario.The main stages of the project included feasibility, environmental permitting, engineering, construction, and commissioning. At the onset of the engineering phase, the mine was scheduled to enter production in October 2008. Through a team effort between AMEC and DeBeers Canada, the schedule was advanced by 6 months towards the goal of project completion in April 2008. Production status was attained in January 2008, approximately 9 months ahead of the original schedule. This paper focuses on the commissioning aspects of the project and includes a less detailed discussion of the engineering stage."

Jan 1, 2010

By H. E. Urtubia

"BHP-Billiton’s Minera Escondida Limitada, in Chile, is one of the world’s largest copper producers. It treats a combined 10,500 tph of copper ore through its two concentrators: Los Colorados and Laguna Seca. The performance of the rougher circuit at each concentrator was measured and analysed using the JKTech flotation optimisation methodology. This involved developing a flotation model for each concentrator based on cell operating parameters (for example bubble surface area flux and froth recovery) and feed ore floatability characteristics. The rougher circuit performance was evaluated in terms of traditional measures, such as grade and recovery. The operation was also analysed using the measured cell operating parameters and ore floatability and the effect of these with regard to performance (grade / recovery) was assessed.This paper presents a comparison of the rougher circuit at each concentrator in terms of these parameters. The main differences in rougher circuit performance between the two plants were attributed to differences in feed ore floatability characteristics and froth recovery. The comparison highlighted opportunities where performance improvements could be made. The study also showed the usefulness of separating the flotation process into easily measurable subprocesses to further identify the different mechanisms occurring in each rougher circuit. Traditional measures like grade and recovery are useful for monitoring flotation operation but this data lacks the depth to determine the root cause behind operational issues. Determining the operating parameters and ore floatability provides the operating plant metallurgist better tools to assess and manage these issues."

Jan 1, 2006

By Kenji Koga

In order to derive the population distribution of gold nanoparticle morphologies as a function of size, highresolution electron microscopic (HREM) observations and structural analyses were done for over 4000 particles (3-18 nm) grown by an inert gas aggregation (IGA) source using helium. To obtain structural features threedimensionally and not to skip high-contrast images, twenty photos were taken for each particle by changing tilting angle of a specimen holder in combination with the through-focus procedure. For the reliable structural determinations, HREM images and their tilting sequences were directly compared with multislice-simulation results for icosahedral, decahedral and face-centered cubic morphologies, and finally the population distribution of each morphology was obtained as a function of size. In the present sample, icosahedral particles were dominantly populated over the whole observed size range and decahedral particles with non-spherical truncated bi-pyramid shape were secondly dominant. Even though a large number of sampling has been done, few crystalline particles were observed.

Oct 1, 2003

By L. C. Bird, N. T. L. Landgren, M. W. Mikhail

"Through funds made available in 1972 by the Nova Scotia Department of Mines and Energy (DME) and the federal Department of Regional Economic Expansion, a program was initiated to recover saleable coal from mine waste dumps adjacent to the existing Acadia wash plant in Stellarton, Nova Scotia.Following evaluation of these dumps in 1972, the Acadia wash plant was modified to treat high-ash material. The first production was recorded in late 1974. By the end of 1979, a total of 738,202 t of dump material had been processed, yielding a total of 205,212 t of thermal-quality coal.The successful Stellarton operation led to considering the possibility of recovering thermal coal from other dumps. Evaluation of the Westville dumps indicated total recoverable reserves of 1,346,617 t averaging 53.8OJo ash.Parameters for plant design were defined from the washability characteristics of the dump material and the results of a bulk test. Two options were proposed; one was to use the existing plant with some modifications, the other was to build a modular mobile plant that could be used at future dump sites in the province after Westville. At the 25% ash level, the potential recovery of coal from the dump was estimated at 41% yield (by weight) or 549,679 t."

Jan 1, 1981

By Peter A. Oshust

The EKATI Diamond Mine has successfully completed the development and commissioning of the Panda Underground Project to extract the ore below the Panda open pit. The dominant kimberlite domain of the Panda Underground, intermixed olivine-rich and mud-rich resedimented volcaniclastic kimberlite (RVK), is very similar to the kimberlite domain characterizing the open pit portion of the pipe. A sublevel retreat mining method is in operation underground at Panda; near-vertical blast rings are drilled and blasted into an open void. Broken ore is mucked with load, haul and dump trucks (LHD?s), sized underground then moved to surface through a conveyor system to the process plant. An advanced feasibility study is in progress at the Koala Underground Project. The Koala pipe is geologically more complex than Panda. The pipe below the open pit is comprised of at least five distinct kimberlite domains. There is a 100 m thick zone of incompetent low-grade mud-rich RVK between the open pit and the stable high-grade olivine-rich primary volcaniclastic kimberlite where mining will be initiated. As a result, it is proposed that Koala will employ sublevel caving; each blast ring shot would be confined and mucked in sequence to maintain the cave of the over-lying low-grade RVK ore. The sublevel cave method seeks to safely defer the mucking of the low grade ore to the latter part of the mine life.

May 1, 2006

This paper discusses how elemental analysis of conveyed bulk flows in real time using PGNAA (Prompt Gamma Neutron Activation Analysis) technology has resulted in significant improvements in advancing plant control in mineral processing operations. Basis of operation of the PGNAA through belt, full stream, continuous, multi-elemental, real time analysis technology is explained. Capabilities and limitations in plant operating environments are discussed including comparison with other real time, online technologies through review of published information available for on-conveyor minerals applications. Case studies demonstrate benefits provided by this technology in two operating mines. An iron ore company had prior experience with the PGNAA analyser technology, implementing an early model in a minerals application in 2003 to develop confidence in its measurement performance and usefulness of the data. A number of analysers were subsequently included throughout the new plant design for extensive measurement and control of conveyed bulk flows, from conveying after mining through to rail load-out. A copper-gold company installed an analyser to address copper ore blending issues where an on-belt system was the only viable option for the degree of control required. Analyser suitability was evaluated through test work on site samples to determine customised multi-element precision guarantees for each application. Analyser results from normal operation are compared against laboratory analyses of multiple cross stream samples collected from conveyed flows to assess performance. Both projects discussed were able to realise benefits previously unattainable for plant quality control, surpassing capabilities of traditional technologies which were either unsuitable for measuring conveyed flows with adequate accuracy or in real time. Equipment payback within a few months was achieved for both sites. Through proven performance in these applications, the companies consider the technology an essential component in advanced plant control necessary in new process flow sheet designs, rather than an optimisation tool.

Jan 1, 2014

By Gheorghe Marin, Franco Chiesa, David Levasseur, Bernard Duchesne

Over the past 20 years, pressure die casting has evolved to a point where structural parts can now be produced by this process. This has been made possible by the development of vacuum die casting and by the development of die-castable, low iron content alloys. This resulted in the production of low porosity, weldable die-cast parts on which heat treatment may be applied. In the present paper, the influence porosities on the tensile properties of as-cast A360 tensile test bars was evaluated. This was done by casting 24 clusters, comprising three 6mm diameter test bars each, in a 280T cold chamber pressure die casting machine after a steady dynamic equilibrium had been reached. Modeling of filling allowed to explain the differences in porosity observed in the 3 samples of a same cluster while the results of solidification modeling were related to the microstructure. Tensile samples were radiographed on a real time X-cube apparatus and separated into 2 lots: samples where no porosity defect were visible and samples with visible defects. By measuring the tensile properties of the 2 lots it was possible to quantify the drop in tensile properties brought about by porosity, which is the most common defect observed in pressure die-cast parts.

Jan 1, 2015

By Mark W. Booth

THIS paper deals with the subject of inbye power as the mechanical . engineer sees it, and invites discussion, particularly from the electrical engineer. At the outset, it will be necessary to clear the ground a little by some definite statements. In this question of compressed air versus electricity for the transmission of power and driving of machinery in underground workings, we must see that there are definite fields that compressed air on the one hand, and electricity on the other, can fill to much greater advantage than the other, and in which there can be little or no direct competition, at least for the present. It is under conditions where these fields overlap, and as to where the line must be drawn between the two, that the respective merits of each must be considered. Steam was the first means used to transmit power from the surface of a mine to drive underground machinery, and so long as distances were short and means possible to ensure fairly efficient use of the steam, and where the fire hazard was not in evidence, it gave fairly efficient service. I have in mind an instance during my own connection with the mines-a duplex pump at the shaft bottom at Princess colliery, driven by steam, and which used the steam compound and condensing; and, but for the mechanical difficulties, it was a not inefficient proposition. The steam was taken direct from the surface boiler-plant through a line down the shaft, and used directly at the pump, being in effect a straight conversion from coal to steam to work done. It was the mechanical arrangement, and failure of the pump in that direction, that led to its removal and replacement by something better in the way of an electrically driven turbine pump. Given modern mechanical arrangements, such as a steam-turbine drive on a high-speed turbine pump, and all other parts made in accordance with best practice in the art of steam generation and use, a steam-driven unit fully as economical would have been obtained. But the central electric supply station, and all that that means or promises (not always the same), turned the scale against steam.

Jan 1, 1936

By Brian Hart, Roger St. C. Smart, James Francis, Mark Biesinger

"There are a number of challenges involved with the surface analyses of different mineral phases from process streams in a flotation facility. The first of course is to collect samples that are representative of the process and to ensure that they remain in a pristine condition prior to introduction into the instrument. In mineral processing, sample collection from the different streams is done on site and preservation involves simply removing oxygen from the sample by bubbling nitrogen or argon gas through the sample and snap freezing with dry ice.The second challenge in studying the surface chemistry of specific minerals is to find reliable methods of mineral phase recognition. In surface analysis of mineral particles confident mineral selection can be difficult with many multi-metal minerals (e.g. chalcopyrite, pyrite, sphalerite) and with precipitated, adsorbed, reacted and contaminant species in the outermost molecular layers.In this paper we show that principal components analysis (PCA) of ToF-SIMS data provides improvement in phase recognition, particle selection and associated variations in surface species. We will demonstrate, with specific examples, that this technique can be utilized to differentiate surface chemical factors promoting (hydrophobic species) or inhibiting (hydrophilic species) flotation.Species recognition based on the PCA method in a study of Cu transfer between chalcopyrite, pyrite and sphalerite mineral mixture clearly identified a statistical difference in copper intensities between the sphalerite and pyrite phases. A similar ToF-SIMS/PCA based study applied to concentrate and tails samples collected from the Inco Matte Concentrator demonstrated extensive CuOH and NiOH transfer between the chalcocite and heazlewoodite minerals. The statistical analysis has been able to confirm some mechanisms and deny others proposed to control recovery and selectivity giving more focus on the control factors.The ToF-SIMS PCA statistical analysis has elucidated differences in surface chemistries which illustrate the discriminating depressant action of adherent aluminosilicate (gangue) fine particles and adsorbed ions on the surface of sphalerite grains. In the flotation test concentrates, HIC conditioning resulted in the removal of these gangue fines thereby improving surface collector attachment efficiency, promoting a greater recovery of sphalerite."

Jan 1, 2007

By Roger Payne, John R. Goode, Feng Gao, James Brown

The Eco Ridge deposit is located in the Elliot Lake mining camp in Northern Ontario, Canada. Between 1955 and 1996, the area produced more than 138,000 t (300 million pounds) of U3O8 and very significant amounts of thorium and heavy rare earths. Based on the NI 43-101 Preliminary Economic Assessment by Roscoe Postle Associates (RPA) dated June 2012, and the economic review by RPA as announced in Pele Mountains’ Press release dated September 12, 2013, the Eco Ridge Mine Project would extract and process 46 Mt of material to produce about 19,000 t (42 million pounds) of U3O8 and about 65,000 t of rare earth oxide (REO) over a 14-year life. This paper discusses process optimization studies including beneficiation and hydrometallurgical testwork. The proposed modified flowsheet includes the flotation and processing of 1) a pyrite concentrate, 2) a dominantly light rare earth elements (LREE) concentrate, 3) a concentrate containing most of the balance of the uranium and heavy rare earths (HREE), and 4) a relatively inert tailings.

Jan 1, 2014

By Diankun Lu, Ganfeng Tu, Edouard Asselin, Feng Xie

A novel separation process for detoxifying cadmium-containing residues arising from zinc hydrometallurgical processes has been developed. An initial investigation indicated that a high concentration of zinc in the sulfate solution can be effectively separated from cadmium by solvent extraction with P204 (di(2-ethylhexly)phosphoric acid, D2EHPA). The mixture of sulfuric acid and ammonium citrate ((NH4)3C6H5O7) is thus used to extract metals from the residue at room temperature. Copper in the leachate is recovered by solvent extraction (SX) with LIX 973. Cobalt in the raffinate from the copper SX process is recovered by precipitation with a-nitroso-ß-naphthol. The results show that more than 50% of the copper and virtually all the zinc, cadmium and cobalt in the residue can be leached under the experimental conditions used here. Virtually all dissolved copper and cobalt can be recovered in the subsequent solvent extraction and precipitation processes. The presence of (NH4)3C6H5O7 could significantly facilitate the extraction of zinc by D2EHPA in the subsequent separation of zinc and cadmium. More than 97% of the dissolved zinc can be recovered through a two-stage counter current solvent extraction process. After separating copper, cobalt and zinc, cadmium can easily be recovered from the solution either by cementation with zinc powder or by electrowinning, while the purified solution can be recycled back to the leaching process.

Jan 1, 2014