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By Mike Robotham

When RFQ?s are received they often contain detailed technical specifications which suggest a departure from the suppliers own customary approach to the design. Both client and end user are quite rightly influenced by their own experiences. The question is who is right, the client and his consultant, the supplier or perhaps a combination of these. This paper looks at some of the fundamental variances that often occur in the approach to the mechanical design of drum hoists, based on our experiences of recent years. Director of Engineering, Mike Robotham is a chartered engineer and has been with DavyMarkham for over 30 years. Having completed a craft apprenticeship he later joined the engineering department as a junior engineer. He has a wealth of experience of working on medium to large engineering projects in the field of mechanical, electrical and hydraulic equipment

May 1, 2011

By D. E. Calisaya, É. Poulin, A. Desbiens, R. del Villar, A. Riquelme

"A 15 cm diameter by 732 cm height, fully automated pilot column was installed in the Agnico-Eagle’s Laronde concentrator (Québec), for evaluating the performance of newly developed sensors and advanced process control algorithms. For eventual comparison purposes, the pilot column is continuously fed with the same slurry feeding the copper-circuit third cleaner column. It is equipped with electrical conductivity-based sensors for estimating the three variables used in the multi-variable control algorithm under evaluation: froth depth, fraction of wash water underneath the interface and gas hold-up. Froth depth is regulated using a PI controller while a predictive controller is formulated as the minimization of the tracking errors of gas hold-up and bias rate, keeping several operating constraints between their practical upper and lower limits. In particular, an unreachable high set point of gas hold-up can be selected in order to maximize the bubble surface area available for particle collection, while maintaining bias rate above a minimum value required for froth cleaning. The proposed strategy may indirectly help optimizing flotation column operation by using these secondary variables, without the implementation of a real-time optimization layer.INTRODUCTION Flotation columns have already been used for more than 30 years, mainly in cleaning stages, as a result of their froth washing capabilities. Despite their widespread usage, the measurement of some pertaining variables and their use for automatic control is rather scarce. Among the most important variables directly related to the process metallurgy (concentrate grade and recovery), froth depth (hf) is the only one normally monitored and controlled. Even though commercial sensors are available, gas hold-up (eg), a variable directly related to concentrate recovery, is seldom measured and never controlled. Another important variable, bias rate (Jb) responsible for concentrate cleaning, is simply not measured at all, as there is no commercial sensor available. Therefore, besides froth depth, continuous monitoring of process variables is limited to flow rates (gas, feed, tailings, wash water), i.e. to manipulated variables. Some new available sensors have been industrially tested, e.g. the Sonar-TracTM for eg (O'Keefe, Viega & Fernald, 2007) and the McGill hold-up sensor (Tavera & Escudero, 2002). Others, for bias rate and frother concentration, have been successfully validated at laboratory scale by Laval’s LOOP researchers (Maldonado, Desbiens, del Villar & Chirinos, 2008b; Maldonado, Desbiens, del Villar & Aguilera, 2010a). Some devices have been extensively used for monitoring bubble size and space distri-bution, e.g. McGill bubble viewer (Gomez & Finch, 2007) and others."

Jan 1, 2012

By Robert Boyd

The Diamond Markets ? Supply has continuously increased over the past 25 years ? However, global supply is expected to drop by 1 to 2% by 2015 ? Demand Driven Market ?Demand is expected to grow 3% annually through to 2015 ? Supply Squeeze Anticipated (2010 to 2015) ? Consumption is exceeding rate of discovery, mine development and reserve replacement ? These fundamentals are driving increased capacity and production at existing mines in South Africa, Botswana and Russia and new areas such as Canada ? Canada is now the third largest diamond producing country in the world ? These fundamentals are also driving record levels of exploration expenditures throughout the world with particular focus on Africa and Canada

May 1, 2006

By J. M. Gregg, C. J. Persellin, I. D. Somerville, E. A. Atekwana, K. L. Shelton

"Zn-Pb sulfide mineralization at Abbeytown mine and Twigspark quarry comprise the only known car¬bonate-hosted base metal sulfide deposits in the Sligo syncline, northwest Ireland. Limestone sedimentation occurred uniformly throughout the region during the Early Carboniferous (Mississippian) as observed by field relationships and lithofacies; however, petrographic and stable isotope evidence indicate that host-rock dolomitization occurred under different conditions at localities to the west and east of the Ox Mountains inlier, suggesting significant uplift and geologic isolation of these areas prior to dolomitization. Localized fluid flow systems are thought to be responsible for sulfide mineralization and associated epigenetic carbonate cements. West of the Ox Mountains inlier at Abbeytown, evidence of three geochemically distinct fluids are observed: (1) a lower-temperature, lower-salinity fluid (70°-130-°C, 4-9 wt.% equiv. NaCl); (2) a lower-temperature, higher-salinity fluid (70°-140°C, 15-24 wt.% equiv. NaCl); and (3) a higher-temperature, moderate-salinity fluid (165°-220°C, 8-14 wt.% equiv. NaCl). Similar fluid types were observed at the Twigspark deposit. The source of the higher-salinity fluid is likely seawater evaporated to near the point of halite precipitation. The higher-temperature fluid is thought to have been derived from deep circulation of basinal brines. It is speculated that mixing of the higher-salinity fluid with the high-temperature fluid was vital for ore formation at Abbeytown because fluid inclusions in sphalerite have homogenization temperatures and salinity values that fall along a mixing trajectory of these end member fluids. Also, areas where the high-salinity end member fluid is absent are barren of sulfides. Less complex fluid systems are indicated for sites east of the Ox Mountains inlier where no sulfide mineralization was observed. Data from base metal sulfide prospects in northwest Ireland indicate no connection with the regionally extensive flow system thought to be responsible for Zn-Pb deposits throughout the Irish Midlands.Les minéralisations en sulfures de Zn-Pb de la mine Abbeytown et de la carrière Twigspark sont les seules gîtes de métaux usuels à encaissant carbonaté connus dans le synclinal de Sligo, au nord-ouest de l’Irlande. Ces carbonates se sont déposés d’une manière uniforme dans la région au Carbonifère inférieur (Mississippien) tel que l’indiquent les relations de terrain et les lithofaçiès; les données pétrographiques et d’isotopes stables indiquent toutefois que la dolomitisation de l’encaissant s’est faite sous des conditions différentes aux localités situées à l’ouest ou à l’est de la boutonnière des Ox Mountains, ce qui suggère un soulèvement et une isolation géologique significative de ces secteurs avant la dolomitisation. L’action de systèmes de circulation locaux sont considérés être à l’origine de la minéralisation sulfurée et des ciments carbonatés épigénétiques qui leur sont associés. À Abbeytown, à l’ouest de la boutonnière des Ox Mountains, on note les effets de trois fluides géochimiquement distincts: (1) un fluide à basse température peu salin (70°-130°C, 4-9% poids équivalent NaCl); (2) un fluide à basse température fortement salin (70°-140°C, 15-24% poids équivalent NaCl); and (3) un fluide formé à plus haute température et salinité modérée (165°-220°C, 8-14% poids équivalent NaCl). Des fluides similaires ont été observés au gîte Twigspark. La source présumée du fluide le plus salin est de l’eau de mer amenée par évaporation près du point de précipitation de la halite. Le fluide à plus haute température est probablement dérivé de la circulation profonde de saumures dérivées d’un bas¬sin sédimentaire. Il est possible que le mélange du fluide à haute salinité avec celui à haute température ait joué un rôle central dans la genèse de la minéralisation d’Abbeytown parce que les températures d’homogénéisation et les valeurs de salinité des inclusions fluide"

Jan 1, 2009

By David Seaman, J-P Franzidis, Emmy Manlapig

"A new device has been developed to directly measure the bubble loading of particle-bubble aggregates in industrial flotation machines, both mechanical flotation cells as well as flotation column cells. The bubble loading of aggregates allows for in-depth analysis of the operating performance of a flotation machine in terms of both pulp/collection zone and froth zone performance. This paper presents the methodology along with an example showing the excellent reproducibility of the device and an analysis of different operating conditions of the device itself.The device has been used to investigate the froth selectivity of attached particles. Simultaneous measurements were made using a different froth recovery measurement technique in the same flotation cell. A comparison of these techniques shows that in this case, particles are selectively detached from bubbles at or near the pulp-froth interface.INTRODUCTIONA flotation cell can be considered to operate in two distinct phases or zones; namely the pulp or collection phase and the froth phase. The pulp zone is responsible for the formation of hydrophobic particle-bubble aggregates, whilst the froth phase is responsible for the separation of these aggregates from surrounding suspended hydrophobic and hydrophilic particles. Thus, the froth phase is the grade determining phase in flotation. A measurement of the bubble load (the mass of particles attached to air bubbles in units of mass/volume) will enable the analysis of the performance of both the collection zone at creating bubble-particle aggregates and also the froth zone at separating these aggregates from surrounding pulp.A measure of froth zone performance that has been used extensively in flotation research is the Froth Recovery, Rf, of a particular system. Froth recovery is defined as the mass of particles collected in the concentrate launder by true flotation as a fraction of the mass of particles entering the froth phase. The measurement of bubble load allows for this term to be calculated easily, rather than having to go through the laborious task of, for example, changing froth depths to determine this performance criterion (Contini et al., 1988; Vera et al., 1999b; Feteris et al., 1987)."

Jan 1, 2004

By René Lefebvre

Numerical simulations of the physicochemical processes related to acid rock drainage (ARD) in the Sugar Shack South rock pile of the Questa Mine were performed with the TOUGH AMD simulator. The objectives were to 1) identify the main processes responsible for observed present-day conditions, 2) provide an estimate of gas phase humidity transfer, and 3) give a preliminary indication of the potential impact of closure involving the installation of an alluvial soil cover. Modeling results indicated that the mine rock geometry (thin layers placed along steep mountain slopes) favors the onset of strong thermal air convection. Simulations also indicate that resloping the piles would not significantly reduce convection and oxidation. For simulation purposes, a potential cover with the permeability range of a local alluvium was investigated and found to be of questionable effectiveness since its permeability can exceed the value of 3x10-13 m2 required to prevent thermal air convection and reduce ARD.

Nov 1, 2002

By H. Soto, J. Jara, F. Nava

"A combination of oxidation and precipitation was used to eliminate cyanide from gold milling effluents. Preliminary laboratory work developed with both synthetic cyanide solutions and with industrial effluents indicated that ozone can easily destroy free cyanide and weakly complexed cyanide (i.e. copper and zinc cyanide). In this case the reaction is quite fast and seems to be controlled by the mass transfer of ozone to the solution. Experimental results indicate that free cyanide and weak-acid dissociable cyanide in mill effluents can be reduced to less than 1 ppm. However, the iron-cyanide complexes proved to be quite resilient to destruction with ozone and they remained in the solution even after most of the free and weakly complexed cyanide was destroyed with ozone. These results were confirmed in a pilot trial developed at the Sphinx plant in northern Quebec.To deal with the problem presented by the presence of the iron complexes two different approaches were studied: use of a combination ozone-ultraviolet light oxidation, and the precipitation of iron-ferrocyanide complexes in the residual solution after ozonation. This last method proved quite promising since reduced the total cyanide levels of industrial solutions assaying as much as 250 ppm to less than 1 ppm of total cyanide. Control of the · pH of the solution was the key to obtain the precipitation of the iron complexes. The use of iron to precipitate cyanide complexes has the advantage of being less expensive and less toxic than copper (used by the Inco process)."

Jan 1, 1992

By K. Schrijver, G. Beaudoin

"Four occurrences of galena-cemented sandstones, exposed in the Lower St. Lawrence - Gaspésie area, are described. They constitute a new, insufficiently explored type of deposit in Quebec.One mineralized body, a minor occurrence, is hosted in Lower Devonian rocks deposited in an estuarine, intertidal river channel during a marine regression; major cements are dolomite and sulphides. Another occurrence, a drilled prospect, is hosted in Upper Silurian rocks deposited unconformably on Cambro Ordovician basement during a marine transgression. With galena and quartz as main cementing minerals, it is similar to some well-known, economic sandstone-lead deposits. A third and fourth, a drilled prospect and a minor occurrence, are hosted in Upper Cambrian rocks deposited on continental slopes. In both, sulphides mainly occupy a secondary porosity. The differences between the third and fourth occurrences are: (1) cementing translucent minerals (carbonates and barite in one; chlorite in the other); (2) chronology of final subsurface dissolution (prior and subsequent to sulphide precipitation, respectively); and (3) important fracture porosity only in the barite-bearing deposit.The diversity of the four occurrences, and the unequal geological knowledge of their respective features, prohibit the formulation of uniform guidelines for further exploration.IntroductionThe attention of the mineral exploration community is drawn to four occurrences of galena-cemented sandstones (Fig. 2A) in the Cambrian of the Taconian Orogen and in the Siluro-Devonian basin of the Lower St. Lawrence and Gaspésie area (Fig. 1). In view of the fact that sandstone-lead deposits (Bjerlykke and Sangster, 1981) are, or have been, mined in several countries (e.g . Laisvall in Sweden: see Rickard et al., 1979; Largentiere in France: see Foglierini et al., 1980), the mere presence of occurrences in Quebec indicates that the mineral potential of some parts of the Appalachians requires further evaluation.Exploration for the deposits considered here is essentially restricted to geological methods and drilJing (e.g . Mainguet Suares and Samama, 1969), since the response to geophysical methods is virtually nil, at least in the initial, surficial stage of an exploration program. As the particular disciplines of geology utilized in exploration depend a great deal on the geological setting of a mineral occurrence, the diversity of the Quebec deposits is of prime importance. Therefore, the four occurrences (Fig. I, Table 1) studied by the authors are herein briefly described with emphasis on their stratigraphic and tectonic setting, and on the evolution of pore space and sequential occlusion of pores and fractures. Prior to further research in and around the occurrences, now in progress (e.g. Beaudoin, 1987; Beaudoin et al., 1987), it is hoped that the following outline will be useful to the explorationist."

Jan 1, 1987

By Monique Pharand, Jeet Basi, Simon Hille

"High quality activated carbon is essential in the recovery of gold in Carbon-in-Leach (CIL), Carbon-in-Pulp (CIP), and Carbon-in-Column (CIC) circuits. Goldcorp’s Campbell complex at Red Lake Gold Mines (RLGM) experienced a period of low soluble gold (Au) recoveries during Q3 2013, during which time the processing plant saw higher than typical Au grades in the CIP tails solution stream. A technical review identified that the CIP circuit may be experiencing a carbon-fouling issue. To further understand the degree of fouling, and to troubleshoot the low recovery problem, samples of carbon were collected from the CIP, elution, acid wash, and regeneration circuits, and submitted for characterization test work. This paper summarizes the steps taken to remedy the carbon-fouling problem at RLGM resulting in increased overall Au recovery.Overview of Red Lake Gold MinesRed Lake Gold Mines is located approximately 450 kilometres northeast of Winnipeg, Manitoba, in Ontario’s western boundary region.All mining is carried out through underground operations, utilizing overhand cut and fill, underhand cut and fill, and long-hole mining methods. Ore types include: silica-replaced carbonate veins with free milling gold, siliceous replacement-type mineralization (rich with arsenopyrite) marginal to veins, broad disseminated sulphide mineralization along major shears, and some minor sulphidized chemical sediment-hosted ore. The operation is supported by two milling complexes: Red Lake, and Campbell.Process DescriptionThe Campbell processing plant's main unit operations consist of grinding, gravity concentrating, flotation, autoclaving, leaching, carbon-in-pulp (CIP), carbon elution and reactivation, electro-winning, bullion smelting/refining and cyanide destruction, and concentrate handling. A schematic of the plant flowsheet is shown in the figure below.BackgroundHigh quality activated carbon is essential in the recovery of gold at many CIP/CIL/CIC processing plants. At RLGM, gold-bearing ore is milled and cyanide is added to leach the gold from the solids into solution. The dissolved gold then comes into contact with activated carbon, and adsorbs onto its highly porous surfaces. Gold is then recovered by separating the activated carbon from the main slurry for further refining. As such, the characteristics and quality of the activated carbon have a significant and direct impact on overall gold recovery."

Jan 1, 2016

By Carlos F. Perucca, Maria Virginia Ramírez A.

"Chile based SQM S.A., exploits potassium chloride rich salts at the Salar de Atacama, in northern Chile. The process includes the solar evaporation of natural brines existing in the Salar salt bed, followed by conventional flotation to recover Muriate of Potash (MOP) for fertilizer use.This paper describes a structured method developed to aid in understanding the metallurgical response of the solar evaporated salts to conventional flotation. The method uses classical metallurgical data analysis combined with laboratory and plant-scale testing, and rudimentary mineralogical studies.As a result of the study, several changes were made to the flotation circuit which produced an operation that is much more consistent and easier to control, and has an increased recovery. An optimized circuit, currently being financially evaluated, has also been conceptually designed based on the findings of this work.INTRODUCTIONSQM S.A. is the world’s largest producer and distributor of specialty fertilizers, iodine, lithium, as well as a wide array of industrial and specialty chemicals. SQM is a public corporation whose shares are traded in the Santiago and the New York Stock Exchanges.SQM S.A. exploits the mineral rights at the Salar de Atacama in northern Chile. Its production processes involve the solar evaporation of natural brines existing in the Salar salt bed, aimed at the recovery of Potassium, Lithium and Boron compounds."

Jan 1, 2004

By W. B. Burchall

Introduction In presenting this paper the author wishes to state that the opinions here given represent only his personal views. A general survey of the subject has been attempted, but such deductions as may have been drawn are not necessarily endorsed by the Company with which he is associated. The aeroplane as an instrument of transport is yet a novelty, for it is only twenty-five years since man first flew. This statement, by itself, may be very deceptive, for compared with the steam locomotive or even the auto-mobile, this infant in industry has made some remarkable showings. The 'actual performance' speed-curve of aircraft plotted over a ten-year period is rising faster than the 'expectancy' speed-curve of 1924 indicated, and it should be noted that, today, the possibilities of 600 miles per hour provoke less scepticism than did the prophecies of 400 miles per hour only a decade ago. Commencing with the remarkable achievement of raising one man into the air, aircraft with an all-up weight of 14 tons are now in daily use on the British airways, and recently a non-stop flight of 5,340 miles was accomplished in an aeroplane, without refuelling. More true than ever is the statement that the records of yesterday are commonplace tomorrow, for new ideas are today seized on and exploited to the utmost once the period of scepticism and doubt has been overcome. In fact, so many new ideas have been brought forward, during the past few years, and applied successfully in our economic life, that one may well ask if today we are not a little too impatient, too exacting in demands, forgetting that real worth-while progress -is attained by no short-cuts.

Jan 1, 1933

By M. Rebolledo, N. Mora, G. Zarate

For decades, the mining industry has been focussed to find an efficient and economically attractive process for the leaching of chalcopyrite. Jetti Resources has developed a novel hydrometallurgical alternative to extract metals of value from mineral ores that the mining industry has struggled to process. Jetti’s catalytic technology, whilst being especially advantaged for extracting copper from low-grade and highly refractory minerals, such as chalcopyrite, seamlessly integrates with existing heap leaching methods and downstream processing operations. The technology uses a catalyst which weakens the metal-sulfide bond in the crystalline structure of the chalcopyrite mineral and alters the structure of the passivation layer allowing the leaching process to continue. Metallurgical test work was conducted to examine the effect of ore variability, in terms of grade and copper deportment. The results presented in this study highlight the amenability of the technology and demonstrate that it is possible to enhance leaching performance of copper primary sulfides over a wide range of copper grades, from 0.1 to 2.2%. Further, it is concluded that despite the copper grade, the tests with increasing chalcopyrite content render copper recoveries up to 4 times higher compared to the tests under non-catalyzed conditions. Jetti’s catalytic technology is currently being evaluated at larger scales, namely a commercial dump leach operation and 50-tonne crib tests. The results obtained thus far are compared to the results from conventional sulfide heap leaching tests. INTRODUCTION For decades, the mining industry has been focussed to find an efficient and economically attractive process for the leaching of chalcopyrite. Chalcopyrite (CuFeS2) is the most abundant and recalcitrant of the copper sulfides (Singer, 2017). Owing to its abundance and economic importance, it is the most demandable natural source for copper worldwide. In fact, the projected demand for copper is further expected to rise much higher beyond the current demand by the year 2020 (Panda et al., 2015). Therefore, it becomes imperative to find low intensity hydrometallurgical technologies for the extraction of copper from chalcopyrite in ores of such low-grades that are un-economic to concentrate and to augment the supply by extracting copper from ores with complex mineralogy that cannot be concentrated (Watling, 2013).

Jan 1, 2019

By Jon R. Maki

"EVTAC, an iron ore mine in Minnesota, had trouble meeting the customer’s pellet silica requirements. In addition, the mine plan was moving towards a lower grade ore and funding was not available for plant improvements to compensate for the change in ore or improving quality. Small changes to optimize various processing equipment resulted in significant improvements in both quality and productivity; for example, productivity on one mill line increased by 10% while producing lower silica concentrate. This paper will provide the methodology that allowed EVTAC to improve quality and productivity through process optimization with little capital investment.INTRODUCTION EVTAC, an iron ore mine in Minnesota, had trouble meeting the customer pellet silica requirements. In addition, the short-term mine plan was changing to a lower ore grade. Because of limited funds, EVTAC did not have the capital for investing in the plant to compensate for the ore change or to make improvements to lower product silica levels. Small changes to optimize process equipment resulted in significant improvements in quality and productivity; for example, one mill line feed rates increased by 10% while also producing a higher quality concentrate. These changes were sufficient enough to allow the mine to lower the target ore grade beyond their initial goal. At one time, a $3M flotation facility was considered as a way to meet quality with the new ore grade. However, the process changes were able to accomplish the same silica reduction with roughly a $50,000 investment in VFDs for sump controls. This paper will discuss some of the modifications that allowed EVTAC to meet the quality and production objectives with little capital investment. It also discusses the methodology used to make these process improvements."

Jan 1, 2014

By B. Hilscher, P. Nayak, N. Yoon

"The mining industry is currently facing challenges with declining feed grades and is struggling to find solutions to improve the project’s economic value. By means of pre-concentration, ore sorting aims to separate the barren material from the valuable ore to reduce energy consumption and tailings generation, while increasing the feed grade, concentrate grade, mill recovery, and revenue. In addition, ore sorting allows the modification of deposit geometallurgy in order to allow the creation of an optimal mill feed.This paper evaluates the applicability and challenges of ore sorting by utilizing the results from four different mines, and reviews them in detail. The mines include two underground and two open pit mines that are base metal and precioius metal operations. In order to understand the applicability of ore sorting in these operations, initial rock-by-rock test results and different types of assays (atomic adsorption [AA], inductively coupled plasma [ICP], and fire assay) are utilized. Using the assay results, the grade recovery curves for ore sorting are generated and they are further improved by using and developing an ore sorting algorithm, which is discussed in this paper. The application and evaluation of ore sorting in greenfield and brownfield properties will also be discussed.The state of the art ore sorting technologies for both rock-by-rock and bulk sorting are reviewed in this paper. The future technologies on the horizon, including different combinations of sensors, are explained. The sorting technologies include, X-ray transmission (XRT), X-ray fluorescence (XRF), colour, infrared, electromagnetic, and laser induced breakdown spectroscopy (LIBS).IntroductionOre sorting is a sensor-based sorting technique introduced between the excavation stage and processing stage, where the unwanted waste is diverted to the waste dump and only the ore is sent to the mill for further processing. As a result, the quality of the material entering the mill is improved and the dilution of the ore is reduced. In greenfield projects, sensor-based ore sorting provides an opportunity to reduce the capital cost of the project and increase the return on investment (ROI). With most operations currently facing the challenge of finding a high grade deposit, having a sorting unit provides several advantages while keeping the cost at minimum."

Jan 1, 2017

By P. Dyas, H. Zouitt, D. M. Smith

"Falconbridge Copper's Lac Shortt gold mine is located in northern Quebec approximately 300 km northeast of Val D'Or and 100 km west of Chibougamau (Pig. 1). Engineering for the mill commenced in early 1983 with a feasibility study. The plant was commissioned in the fall of 1984 at a capital cost of approximately $12 million. Design capacity was 750 tpd which was increased in the fall of 1985 to the current level of 1200 tpd.The ore at Lac Shortt is free milling, grading an average of 5.5 g/t gold which is finely disseminated throughout the host rock. Pyrite at 3 to 5% by volume and traces of copper mineralization are also present.Some of the latest gold processing techniques known at the time of design were incorporated into the mill. These include carbon-in-pulp, pressure stripping, electrowinning of pregnant solution and induction furnace refining. The plant also features several innovations such as a unique interstage carbon retention screen in the CIP circuit and the outdoor location of the cyanidation feed thickener, mill solution tank and reagent storage silos despite -40° Celsius winter temperatures.This paper describes the current mill process and discusses some of the problems encountered during the first two years of the plant's operation. CRUSHINGThe Lac Shortt surface crushing facilities are located in a separate building, isolated from the wet processing circuits for dust and noise control reasons. The crushing plant equipment was originally utilized at the Manibridge operation in northern Manitoba where it had been designed to operate at 135 tph. However, at Lac Shortt a rate of only 80 tph has been achievable to date, mainly due to the hardness and frequently slabby breakage characteristics of the ore. Therefore, in order to meet fine ore requirements at the current mill throughput of 1200 tpd, the crushing circuit is run seven days a week. 24 hours a day. Availability has been averaging 65%."

Jan 1, 1987

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

By Gavin Ritson, Chris Ward

"The oil sands industry is still fairly young with the first viable oil sand operation having been started in Alberta in 1960. Since then numerous modifications and improvements have been tried and implemented. The current process makes use of high velocity pumping of oil sands slurry with hot water (hydrotransport) to achieve separation of bitumen from the sand.A number of the oil sands processes have been adapted from unit operations that are used in mineral processing, such as crushing, screening, flotation, cycloning and thickening. This paper outlines a typical oil sands process flowsheet and investigates the differences and similarities in technologies and costs to other mineral processing industries. It also considers the very large throughputs required, and presents some of the difficulties and challenges currently faced by the industry as a result of high demand for oil and environmental pressures.INTRODUCTIONOil sands (also known as tar sands) deposits are found throughout the world. The Athabasca Oil Sands deposit in Aberta is the largest of these. Oil sands consist of a mixture of crude bitumen (a semi-solid form of crude oil), silica sand, clay minerals, and water. The Athabasca, Peace River and Cold Lake deposits cover 141,000 square kilometers and contain about 1.7 trillion barrels (270×109 m3) of bitumen in-place, comparable in magnitude to the world's total proven reserves of conventional oil"

Jan 1, 2009

By J. -P. Saindon, L. D. Nel, A. E. Hall, S. G. Hardcastle

"This paper reports on an investigation into gas and dust concentrations in Ruttan Mine's exhaust air. The values obtained indicate that there is excellent potential to recirculate approximately 25% of the hot exhaust air into the intake air to reduce winter heating costs. Contaminant concentrations vary significantly during the course of the working shift and decrease in the mine exhaust system as the air returns to surface. A proposed on-line control system is outlined which would permit recirculation to be implemented with a pay-back period of less than two years. IntroductionIncreased energy costs and depressed mineral prices have resulted in mines, which use winter ventilation air heating, reviewing their systems to try to reduce costs. Heating costs can be significant, for example, Potash Corporation of Saskatchewan spends an average of $580,000 per mine per year and Ruttan mine spends approximately $IM per year on propane for its direct-fired heating system.Several method s of reducing heating costs have been considered and the following have potential application.Heat Exchange Between Exhaust andIntakeThis is usually accomplished by run-round glycol systems. The system is limited by ice formation on the coils in wet exhaust air and by the low exhaust air temperature, usually l0ºC. It also requires close proximity of the intake and exhaust airways to ma~e the cost of the connecting pipeline and pump systems economic . A feasibility study by Inco's Thompson operation reported that a proposed system of this type had a 19-year payback period and was, therefore, uneconomic. Potash Corporation of Saskatchewan is currently investigating plastic heat exchangers for a trial system because of corrosion on metal exchangers. It has the advantage of a 17°C exhaust temperature and relatively dry exhaust air.Waste Heat ReclamationThe waste heat from compressors and hoists can be used for heating in some mines. The feasibility of such a system depends on the individual layout and the proximity of the heat source to the inlet airway. Other mines have considered using the exhaust air in greenhouses to provide a cash crop."

Jan 1, 1988

By Claude Bazin

"The On-Stream Analyzer has proven and is still proving to be an extremely valuable tool for the control of flotation circuits. This paper examines the possibility of going further in the utilization of the provided assays using a real-time material balance program to calculate the distribution of solids within the streams of a circuit. Mass balance results can be used for process control, process analysis and detection of sensors malfunction. Examples from 3 Canadian and one American concentrators are presented to illustrate the potential of the method.IntroductionThe On-Stream Analyzer (OSA) has gained, over the last two decades, the status of key instrument for the control of flotation plants. The OSA is currently used in almost every sulphide flotation plant and its application in oxide mineral flotation plants is increasing. On-Stream Analyzers provide X-rays pulse counts that are converted into assays using multilinear regression programs. The estimated assays are passed to the flotation operators, via an operator console, or to control loops of various degrees of complexity (McKee, 1991) implemented in a Distributed Control System (DCS). Operators and/or controllers take control actions based on these assays to ensure an adequate operation of the plant. Although this application pays off very rapidly for the purchase of the OSA, one should ask: Could we get more from the OSA?Some plants reported the use of OSA measurements to process optimization (McKee, 1991). The optimization strategy is based upon economic indices calculated from metal recovery using the 2 product formulae (Wills, 1992, page 124). The 2 product formulae is however sensitive to measurement errors in the assays and can lead to considerable scatter in the calculated indices (Hodouin et al., 1993). Least squares algorithms provide an interesting alternative to filter out measurement errors (Spring, 1992). This paper presents a recursive least squares algorithm that estimates in a real time fashion the mass flow rates in a flotation plant using OSA and mass flow measurements. The algorithm is robust and its recursive structure is not demanding in terms of computation time and memory. The method was tested with data from four concentrators. Results of the material balance algorithm prove to be useful to detect sensors malfunction and may potentially be used for the control and optimization of flotation plants.The paper is divided into two sections. The first section gives a description of the proposed method. The mathematics of the method are kept to a minimum, since the detail is presented elsewhere (Bazin and Franklin, 1994). The second section shows the application of the method to different flotation plants."

Jan 1, 1995

By T. R. Raponi

"The Williams Mine, Canada's largest gold mine, processes over 6,000 t/d of ore utilizing SAG/ball milling, leaching and CIP, carbon stripping, electrowinning and refining to produce gold dare bullion.Grinding accounts for over 50% of milling costs with grinding media, power and mill liners making up over 75% of grinding costs. Since 1991, several changes in these areas have been made which have significantly reduced costs, while fineness of grind and mill recovery have both been increased.This paper discusses the changes made in the grinding circuit over the past few years and assesses their impact on operating costs and mill operations.IntroductionThe Williams Mine is located in the Hemlo area of northwestern Ontario, about 40 km east of Marathon. It is operated by the Williams Operation Corporation, which is equally owned by Teck Corp. and Homestake Canada Inc. Canada's largest gold mine, the Williams Mine commenced operation in October 1985 at a rate of 3, 000 t/d. Mill throughputs have typically exceeded design, averaging 3, 397 t/d in 1986, and 3,380 t/d in 1987. In August 1988, production was increased to 6,000 t/d. Throughput averaged 4,212 t/d in 1988. Production increased over the next few years averaging 5,477 t/d in 1989, 6,248 t/d in 1990, 5,987 t/d in 1991, and 6,283 t/d in 1992. With a recovery of over 95.5%, production for the first three quarters in 1993 is averaging 6,408 t/d.GeologyThe main ore body is a steeply dipping conformable zone of microcline-quartz-muscovite rock. It occupies the contact zone between hanging wall metasedimentary rocks and foot wall felsic quartz feldspar porpyritic rocks of possible volcanic or subvolcanic intrusive origin. The ore body is enveloped by muscovite schists which are thickest on the footwall side. The schist is enriched with tourmaline, pyrite, and green mica containing vanadium and barium. The ore body contains pyrite and barite which occurs mostly in laminae and bands to veinlets and breccia fillings. The gold occurs as free (native) grains, 20 to 30 µm in size at grain junctions of the microcline and quartz. Visible gold is rare in the main zone. There are commonly two or more discernable layers of economic value which are separated by weakly gold mineralized material which usually consists of muscovite schist, barite rich zones or sulphide poor-microcline-quartz rock and in the upper and western fringes by biotite rich schist with feldspathic fragmental characteristics. Molybdenite is a common constituent as very fine disseminated grains in the microcline-quartz rock and is most prominent with gold enrichment. Stibnite and realgar are two of the more common accessory sulphides."

Jan 1, 1994