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By Les Johnston

_ BACKGROUND - About EPCOR - Genesee Generating Station - Phase 3 Expansion _ TECHNOLOGY SELECTION - Selection Criteria - Combustion Options - Flue Gas Emission Control Options _ STAKEHOLDER VIEWS _ PROJECT STATUS _ EPCOR is an integrated utility company for water, gas, electricity and technology services. _ EPCOR has about 1.6 million customers in Alberta, Ontario, Manitoba, BC, and the U.S. Pacific Northwest. _ EPCOR Generation Inc. operates three power stations in Alberta which were in operation before deregulation, including the coal-fired Genesee Generating Station. _ EPCOR Power Development Corporation owns generating stations in Alberta, BC and Washington State and will be building the Genesee Phase 3 expansion.

May 1, 2002

By Marius Jacobs

"Safety performance in many companies and even industries has stalled in the few years. Accidents rates are at a "plateau" and yet, serious accidents and fatality rates are not. In more dramatic cases, such as in the BP Texas disaster, organizations that have "exemplary" safety statistics, suddenly have a catastrophic or multi-fatality event occurring. Other classic examples are the Piper Alpha disaster and NASA’s Challenger and Columbia disasters and even the Chernobyl nuclear reactor. Looking into the root causes of these accidents provides an insight into the events and deficiencies that led up to the accident, but what are the common features in the organization’s mindset? What characterizes these organizations’ decision-making, their approach to safety and to risk and are there specific cultural features that can be delineated? The research and review presented in this paper covers a period since 1994, which started in the Australian resource industry and since then covered international events. The features of these organizations are summarized as the seven deadly delusions, based on extensiveresearch since 1997 of organizations that suffered unexpected disasters.The Piper Alpha Oil Rig disaster in the North Sea, on the 6 July 1988, was one of the most pivotal events in safety around the world. It changed the thinking and focus of governments, whole industries and led to numerous books and papers. It resulted in new legislation, textbooks and a critical self-examination by the oil and gas industry.In short, an explosion and fire occurred when a pipe started leaking gas and ignited. A temporary flange, with no safety valve, was used to block off this pipe during a maintenance operation the previous shift. The permit to advise operators not to start the pumps on this line was misplaced and lost. Several deficiencies, problems and system failures coincided. A key factor was that the water deluge system was inoperable at the time and failed to extinguish the large fire that erupted, followed by an even larger gas explosion. The accommodation unit, situated on top of the oil rig, was the main "killing field" - most men gathered here to await instructions (which never came) and where they died from smoke inhalation. Later, a large explosion of the gas pipeline from an adjoined rig exploded and killed more people.The line of events and the associated system failures are all very relevant in the analysis of the accident, and provide the only insight into what caused the accident. But much "further back", inside the organization’s culture, lurks more dark matter. The first inclination is to ask what was "deficient" in the culture. Did they not care enough about safety, or about their people? Did they have a culture where production decisions were more important than safety considerations? Did they ‘coerce’ supervisors and employees to ignore safety precautions or did they just "fly by the seat of their pants"?Not surprisingly, it is very difficult to identify the true nature of the culture in that business because in such an aftermath of death and destruction, no one dare say that the safety culture was a ‘positive one, focused and caring’ or that the company was doing well in safety and that this is only a freak accident. Indeed, there were many deficiencies in the organization’s systems and procedures, such as the permit to work system.But there are some niggling questions: How is then that the Piper Alpha Oil Rig was actually considered the company’s most productive and safest oil rig in the North Sea? Why would this rig win a safety competition, 6 months before the disaster, with the deficient permit as its most outstanding successful system?"

Jan 1, 2014

By Brad Wells, Wayne Bull, Wayne Dickinson

"Antiscalants were evaluated for control of calcium carbonate (CaCO3) in gold processing applications. Under severely supersaturated conditions, 100 percent inhibition was achieved with 30 ppm antiscalant. Laboratory and field testing established that an antiscalant could both inhibit scale buildup and remove an estimated 0.5 kg/m2 per annum of pre-existing scale. A program was developed to control CaCO3 at a gold mill experiencing severe scale buildup. Annual accumulation of as much as 3 cm of scale in process piping was reduced to unmeasureable levels when 10 ppm antiscalant was applied. No scale-related upsets in mill operation occurred during a five-month trial period.INTRODUCTION Inorganic mineral scale is a crystalline deposit that forms when dissolved mineral constituents exceed the solubility of the respective mineral phase. Formation of mineral scale adversely affects a wide range of industries and is of particular interest in mining and metals processing. Scale affects numerous stages of metal extraction processes. Restricted flow in piping, nozzles, valves, screens, pumps and other components used to transport mineral slurries, metal concentrates, and tailings as well as scale in millwater and thickener overflow circuits are primary concerns (Alfano & Boffardi, 1994). Heap leaching, comminuation, flotation, vat leaching, carbon adsorption, and heat exchangers as well as oxidation steps used in processing sulfidic ores are among key unit operations that may be adversely affected (Simmons & Gathje, 2003). Antiscalant chemicals are designed to prevent formation and growth of mineral scales such as CaCO3. These chemicals, which include two primary classes – phosphonates and anionic carboxylate polymers and copolymers - are added to the gold processing stream at low parts-per-million (ppm) concentrations to interfere with nucleation and growth of scale forming crystals and to disperse fine particulate material. Application points may be located throughout the gold extraction process. Evaluation of the performance of antiscalants plays a critical role in determining the best product for a specific application. Performance evaluations include laboratory testing, pilot scale studies, in-plant trials, and ongoing performance monitoring during mill operation."

Jan 1, 2014

By Andrea McGlynn

Iron Ore Company of Canada, Labrador City 2011?Canada's largest iron ore producer, leading global supplier of iron ore pellets and concentrates ?Rio Tinto (58.7%), Mitsubishi Corporation (26.2%), Labrador Iron Ore Royalty Income Fund (15.1%)

May 1, 2011

By Kevin M. Ansdell, Irvine R. Annesley, Christine L. Mckechnie

The U-Th-REE mineralization at Fraser Lakes Zone B is hosted by granitic pegmatites and leucogranites, which lie along the deformed contact between Paleoproterozoic metasedimentary gneiss of the Wollaston Group and Archean orthogneiss, approximately 25 km from the southeastern edge of the Athabasca Basin. The pegmatites/leucogranites are subcordant to concordant with the regional foliation and are concentrated within a northeast-plunging antiformal fold nose, the study area, which lies west of Fraser Lakes. The mineralized pegmatites/leucogranites in the western part of the study area (Group A) are typically enriched in U (± Th) with Th/U ~1, and contain uraninite, thorite, zircon, and allanite. Those intruding the central part of the study area (Group B) are generally enriched in Th and LREE, with Th/U >2, and contain monazite, thorite (commonly U-enriched), and zircon. The pegmatites and leucogranites in Group A tend to be slightly enriched in SiO2 and depleted in TiO2 relative to those in Group B and are interpreted to represent more evolved crustal melts. Both groups are peraluminous and show varied chemistry. Partial melting (~850ºC and 9 kbar) of a metasedimentary rock-dominated source, entrainment of accessory minerals as xenocrysts, and assimilation-fractional crystallization processes combined to enrich the granitic pegmatites/leucogranites in U, Th, and REE elements. Transfer of melt from the source region to the crystallization sites was assisted by deformation within and along major structural zones, such as the folded Archean-Paleoproterozoic discontinuity. The character of mineralization and structural control in the study area is reminiscent of the alaskite-hosted deposits at Rössing, Namibia.

Jan 1, 2013

By Marty Hudyma

Large seismic events have been reported in mines in the Sudbury mining camp for more than 70 years. Nevertheless, no detailed record of the events has been compiled. In 2008, the Sudbury Regional Seismic Network (SRSN) research project was initiated to collect more accurate data with regard to the magnitude and locations of mining-induced seismic events in and near the mines in the Sudbury Basin. The data is used to better understand the mechanisms of the events and cause-effect relations between mining and seismic events. Through the collection of a central database of large seismic events, new insight is being be gained into why some mines are much more prone to large events than others. Fifteen low cost seismic stations have been distributed throughout the Sudbury basin. The data from each seismic station is uploaded to a central server using the internet. Data recorded on the SRSN is processed on a daily basis, and a weekly summary of blasts and events is issued to project sponsors. Seismic events smaller than local magnitude +1.0 have been identified and located. Event location accuracy is less than 2 kilometres, however, many events have been located less than 1 km from a mine. The SRSN fills a seismic monitoring gap between the in-mine microseismic monitoring systems and the earthquake monitoring system operated by the Geological Survey of Canada. Since July 2008, more than 600 mine blasts and more than 450 mining-induced seismic events have been recorded in the Sudbury basin. This paper primarily discusses the technical aspects of the design and operation of the SRSN. The SRSN is a Canadian Mining Industry Research Organisation (CAMIRO) research project, with industry sponsorship and support from FNX Mining, Itasca Canada, Vale Inco and Xstrata Nickel.

Oct 1, 2010

By Takahiro Kubo, Katsunori Yamaguchi, Hidehiro Sekimoto

Equilibrium relation between B2O3 slag, RExOy-B2O3 (RE = rare earths) slag and Fe-C alloy formed by melting treatment of neodymium magnet and B2O3 was investigated. When neodymium magnet was melted together with B2O3 and Fe-C alloy in carbon crucible, 3 liquid phases of B2O3 slag, RExOy-B2O3 slag and molten Fe-C alloy formed and clearly separated by the difference of the specific gravities. In the case that excess amount of Cu was also introduced in that system, molten Cu phase additionally formed. Almost all amount of RE were concentrated in RExOy-B2O3 slag. The concentration of RE in RExOy-B2O3 slag increased with the decrease of the melting temperature. While chromium, phosphorous, nickel, cobalt, and copper were concentrated in molten Fe-C alloy, silicon and aluminum were distributed in B2O3 slag and RE2O3-B2O3 slag.

Jan 1, 2014

By Don Welch

Pressures for change ?Land use constraints ?Project financing ?Local communities ?Environmental issues ?Sustainability requirements ?Stricter regulatory procedures ?Technical excellence ?Reduce risk ?Impacts of failure & non-compliance

May 1, 2010

By Mani Manimaran, Inna Dymov, Mariam Melashvili, Chris Fleming, Joe O’Day

This paper presents experimental evidence that supports the use of bromine/bromide as a potential alternative to conventional cyanidation for gold leaching. The study evaluated a brominebased lixiviant, Stabilized Bromine, with considerably lower vapour pressure than liquid bromine. Using a rotating device, the rate of gold dissolution was determined at various concentrations of this reagent. The reactivity of pure pyrite, arsenopyrite and chalcopyrite minerals was also evaluated in stabilized bromine reagent. Furthermore, bromine leaching of gold in a number of gold bearing ores was undertaken. Results showed that significantly higher gold recovery can be achieved with bromine than with cyanide when leaching gold encapsulated in sulphides, but bromine consumption was high owing to simultaneous oxidation of the sulphides. The greatest promise for the bromine leach process was with oxidized gold ores. The recovery of gold from oxide ores with bromine was comparable to that achievable with cyanide and bromine consumption was reasonable when leaching was conducted at a near neutral pH of ~6. In the case of oxidized gold ores containing copper mineralization, it is possible that bromine consumption may be lower than cyanide consumption, since there is evidence to suggest that bromine is less reactive than cyanide with copper minerals.

Jan 1, 2014

By M. Y. Solar, W. G. Davenport

Most of the recent growth in nickel demand has been for the production of stainless steels and virtually all of it has been satisfied by new ferronickel and nickel pig iron projects. But "good" laterite resources are more and more difficult to find: Ni grades are decreasing while Fe contents are increasing and SiO2/MgO ratios vary from 1 to 3 and even higher if limonites are included. Predicting the smelting behaviour of such ores requires a more fundamental understanding of the thermodynamics of these systems in commercial operations. One valid question is thus whether these furnaces are at thermodynamic equilibrium or not. The present paper investigates this question, compares calculated and measured O2 partial pressures and mechanical/chemical slag loss ratios and concludes that ferronickel furnaces are not at thermodynamic equilibrium. This departure from expectation is actually to the operators’ advantage: the targeted ferronickel grades can be obtained at lower reduction potentials than calculated from pure thermodynamics.

Jan 1, 2014

By Patrick Pelletier, Pierre-Alexandre Bossé, Julie Fournier, Gianni Bartolacci, Jayson Tessier, Ahmed Bouajila, Carl Duchesne

"This paper summarizes research into the study of the control of flotation processes based on froth images. The use of numerical image analysis techniques for the extraction of significant patterns (froth structure and colour) from industrial flotation froths is discussed.First, the froth was analysed by the use of the Multivariate Image Analysis (MIA) method to extract the spectral variation contained in a RBG image. The Partial Least Squares (PLS) was applied to develop the empirical model for the prediction of froth grade. The results of this application are illustrated using one industrial case study.Second, the froth was also analysed by Gray Level Co-occurrence Matrix (GLCM) and Wavelet Transform Analysis (WTA) to extract features related more to morphological aspects. Since there is useful information hidden in froth texture, these methods are used as texture descriptor to classify different types of froths.Third, a control strategy based on a froth structure indicator was developed and implemented on an industrial zinc flotation circuit. The feedback controller uses a reagent flow-rate in order to maintain the froth structure at its set point. Process improvements obtained with the implemented control strategy are highlighted.Finally, the feasibility to implement a hybrid control strategy consisting in a froth structure supervision controller based on the froth concentrate grade estimated by MIA and recovery inferred by image analysis is discussed.INTRODUCTIONThe development of control strategies to achieve satisfactory control performance has always been a great challenge for engineers and the need for improved process diagnosis, control and optimization has become more and more evident for the mineral processing industry in the last decades. That is why new process variables need to be measured particularly in highly multivariable processes such as flotation. This industrial process is subject to a wide variety of disturbances mainly generated by frequent and sometimes abrupt changes in physical and/or chemical ore characteristics and also, due to some irregularities in manual process operating procedures. A flotation circuit scheme is always a complex network of more than two dozens slurry streams. Information about those streams (% solid, metal content analysis and flow rates) is important for process diagnosis performance evaluation and control. Also, because of the grade decrease and increasing complexity of the new processed ores, more instrumentation outputs and more powerful and significant pr"

Jan 1, 2005

By S. McPhail, D. Richardson, G. J. Simandl, C. Akam, S. Paradis, M. Yakimoski, A. Teucher, Y. Cui, F. Ferri

Historically, extracting dissolved solids from formation water was economically motivated. Today, main drivers are environmental benefits and regulations, as large volumes of water needed for hydraulic fracturing require treatment before reuse or disposal. The concentration of dissolved solids in flowback water increases with each use and may require treatment prior to disposal. Element recovery from produced water is not profitable unless market conditions are favourable, recoverable elements are abundant, and economical recovery methods are established. Sale of recovered materials could offset recycling and disposal costs. This paper describes markets for Cl, Na, Ca, K, Sr, Mg, Br, Ba, I, B, and Li, and their concentrations in produced water from oil and gas wells in British Columbia. It recommends revising sampling protocol for produced water.

Jan 1, 2018

By Cosmin Carpinisan, Erich J. Hofmann, Stephen J. Hall

"Since presenting a technical paper regarding their unique capabilities in Forged Steel Mill Gearing at the SAG-2006 Conference, Australian heavy engineering company Hofmann Engineering has pioneered a number of new manufacturing processes and design concepts for components of large comminution equipment. These include: 1. Novel design improvements for HPGR Rolls with forged steel tyres and a unique patented tungsten carbide insert designed to improve wear life, enhance autogenous layer build-up, and to reduce breakage & chipping under load. 2. Development of forged fabricated Mill Heads using rolled & welded high-tensile steel plate as alternatives to cast conical mill heads. 3. Insitu Girth Gear measurements for profile and wear via portable 6-axis CMM. 4. Gear and Pinion designs to AGMA-6114 for SAG mills of 38’-40’ diameter to 24MW and for Ball Mills of 26’ diameter to 18MW. The paper presents case studies from the Australian heavy manufacturing facilities of Hofmann Engineering, combined with news of their new gear manufacturing and gearbox overhaul facility in Canada."

Jan 1, 2012

By J. Don Scott

Analytical predictions of the rate and magnitude of settlement of deposited oil sands tailings slurries generally overestimate how fast pore pressures will dissipate. Field deposits of nonsegregating tailings to mature fine tailings show continued high pore pressures near the surface which impede surface reclamation. In geotechnical analyses which predict the consolidation behavior of soft soils a finite strain theory is used. Effective stress-void ratio and void ratio-hydraulic conductivity relationships determined from laboratory large strain consolidation tests, are used in the finite strain predictions. This theory, however, cannot predict the full range of sedimentation, consolidation and pore pressure dissipation which occurs in large scale deposits of thixotropic tailings slurries. A new large strain consolidation model which assumes that the creep rate of the slurry exceeds the pore pressure dissipation rate is being investigated. This model is relevant for rapidly deposited, low permeability thixotropic slurries where the upwards drainage path increases by several meters a year, such as, in oil sand fine tailings ponds and nonsegregating tailings deposits. The model will be verified by analyzing the 10m high column of fine tailings at the University of Alberta which has been monitored for over 20 years and in which the excess pore pressures are still very high.

May 1, 2004

By D. F. Cooper, J. G. Paterson, K. H. Pang

"Effective control of metallurgy by manual adjustment of cell levels is common flotation practice. With an on-stream XRF analyzer interfaced to a process control computer it is possible to program the computer to carry out this function automatically. This paper describes the development and implementation of closed loop control of the concentrate and tailing grades at the Clarabelle Mill of the International Nickel Company of Canada, Limited, The XRF analyzer was used as the sensor, cell level as the control and the computer as the controller.IntroductionThe International Nickel Company of Canada, Limited recently brought on-stream Clarabelle Mill having a rated capacity of 35,000 tons per day. The plant was required to increase milling capacity in the Sudbury area by 9,000 tons per day and to improve milling efficiencies by replacing the obsolete crushing and grinding equipment at the Copper Cliff Mill. This represents the fourth mill built since 1959 and incorporates the latest thinking in a continuing evolution of instrumentation and control concepts. Table 1 illustrates control progress at Inco since 1959.In 1967 Frood-Stobie Mill came on-stream incorporating a central control room, an on-stream analyzer, a data gathering computer, and a significant change in instrumentation from direct-contacted pneumatic to miniature electronic. The computer successfully controls the analyzer but has very limited process control capability. Based on this experience a process control computer system was installed at Clarabelle Mill with the objective of carrying out extensive supervisory control and a limited amount of direct digital control."

Jan 1, 1973

Peñasquito is Mexico's largest gold producer, consisting of two open pits - Peñasco and Chile Colorado - containing gold, silver, lead and zinc. Over the next three years, mining activities in the pit are expected to be focused on lower grade ore in the upper parts of the Peñasco pit while stripping is emphasized to ensure an economically optimal pit shell design to maximize the net asset value of the operation. By 2019, Peñasquito’s gold production is expected to benefit from an improvement in mined grades as it recommences mining higher grades at the bottom of the Peñasco pit and significantly enhanced metallurgical recoveries with the planned completion of the Pyrite Leach Project ("PLP").

Jan 1, 2017

By Faan Bornman

"Reeves and Platt1 stated that dense medium separation is one of the most complex unit processes in mineral processing today particularly if cyclones are used. It is also the most efficient gravity concentrating process available to process engineers. The complexity of the process and large number of design and operating variables means that the process has largely remained more an art than a science. Dense medium separation is well established in the diamond, coal and iron ore industries but is gaining popularity as a pre-concentration step in other industries. The maintenance issues are addressed that will affect the efficiency of the operation.INTRODUCTION The purpose of the dense medium separation (DMS) process is to separate the valuable material from the waste based on gravity differences. However, the specific gravity difference between the two fractions must be large enough to achieve high efficiencies. Heavy particles sink through the dense liquid and light particles float. DMS is also used for the pre-concentration of minerals before further downstream processes like communition, in order to minimise the treatment costs. Examples are the pre-concentration of diamond ores or metalliferous ores like nickel, copper and cobalt. Dense medium separation is also used to upgrade the material to meet different market specifications, for example in coal and iron ore applications. A typical dense medium separation process for a diamond application is shown in Figure 1."

Jan 1, 2014

By Mike Johnson, Niels Verbaan, David Dreisinger

The Search Minerals Foxtrot project in Labrador represents a significant Canadian resource of rare earth elements rich in the sought after heavy rare earth elements (19.8% HREE/TREE). A preliminary economic assessment of the project indicated that the project is technically feasible and economically attractive. A variety of metallurgical test programs have been undertaken which have led to significant streamlining and simplification of the process flowsheet. The improved flowsheet should allow Search to reach production earlier and will use conventional processing equipment. The results of these test programs are presented and discussed in this paper.

Jan 1, 2014

By David R. Macedon

"Through the years, a wide variety of dust control methods have been utilized at mineral processing operations. While some have been successful, many have been highly ineffective. Dust Control systems currently in use include baghouse systems, fog systems, surfactant spray systems, and foam dust suppression. While baghouse systems can be effective, they are capitalintensive and costly to operate and maintain. Chemical dust control programs can be very effective. However, if applied incorrectly, they can have detrimental effect on mineral recovery. Thus, many operations utilize a combination of baghouses and water, often with limited success.Recent advancements in surfactant and polymer chemistry have resulted in substantially improved chemical dust suppression programs. These products range from non-corrosive surfactant/humectant combinations for road dust control to foam-based systems for crushers and transfer points, to advanced polymers for pile binding and soil stabilization. These advances are discussed in detail, citing results from fieldwork in the precious and base metals industries.INTRODUCTIONThe global nature of the mineral processing industry presents a unique set of challenges. Traditional thinking would tell us what works in one place should work in another. This could not be further from the truth in the area of dust control. We learn very quickly that there are a number of factors that can affect the efficiency and success of a dust control program and that these factors are not all chemical or equipment related. Some of these factors include facility maintenance, product selection, water quality and characteristics, and economic considerations.What has been learned from past experience is that each mineral processing plant presents a unique set of factors that will affect the ability to create an optimal dust control program. This paper presents a myriad of treatment options that will highlight the advancements in chemical dust suppression products and equipment."

Jan 1, 2004

By H. Zhu, Y. Sato, O. Takeda, K. Nakano

Recycling of rare earth magnet wastes is essential to insure the stable supply of rare earth resources. For the development of a novel recycling process, the removal of rare earth oxide from an off-spec alloy magnet was investigated by melting the alloy magnet at 1503 K together with fluoride flux, LiF-50 mol% NdF3 and LiF-?25 mol% NdF3-25 mol% DyF3. After melting, the separation of magnet alloy from the fluoride flux was achieved, and neither suspension of alloy in the flux nor suspension of flux in the alloy was observed. Oxygen concentration in the alloy decreased from 5000 mass-ppm to 160 mass-ppm by utilizing 1.5 times of equivalent amount of flux needed to completely dissolve the oxide. The investigated process is suitable for mildly contaminated waste such as a used (end-of-life) magnet because of its simplicity, low energy consumption and small limitation on location for operation.

Jan 1, 2014