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By A. Azizi, P. Blatter, A. Bouajila

"Due to the high reactivity of sulfide minerals in alkaline cyanide solutions, some parasitic reactions inflict a heavy gold surface passivation and excess cyanide consumption resulting in a dramatic decrease of the gold leaching rate. Atmospheric pre-oxidation was shown to be an effective tool to enhance gold extraction by preventing a passive film from forming on the surface of gold grains. This work aims to highlight efforts undertaken to determine: (1) how gold cyanidation is limited by passivation; (2) what are the reactions and mechanisms involved during gold cyanidation; and (3) how a better understanding of fundamental issues can be used to design a proper pre-oxidation strategy. INTRODUCTION Precious metals (PM), gold in particular, naturally occur in contact within a wide range of sulfide mineral systems. Hence, one of today’s most challenging R&D tasks consists in accounting for the presence of sulfides on the cyanidation behavior of gold. An important body of knowledge reveals that metal sulfides display a range of reactivities in alkaline cyanide solutions (Marsden & House, 2006). Such reactivities are acknowledged to inflict additional utility costs and loss of profits because they are accompanied with higher consumption of cyanide and/or formation of undesirable by-products that are often detrimental to gold leaching rates. Gold recovery in cyanidation is hampered by a multitude of factors, among others: (1) consumption of excess cyanide as a result of the formation of thiocyanate and dissolution of transition (Cu, Fe, Zn, etc.) metals (Habashi, 1967); (2) gold surface passivation by solid reaction products, e.g., Fe(OH)3 (Guo, Deschenes, Pratt, Fulton & Lastra, 2005), sulfur (Dai & Jeffrey, 2006; Jeffrey & Breuer, 2000;) or oxo and thiooxo (SbO33- SbS33-) salts in alkaline solutions (Guo et al., 2005). Because of their energy structure, most of the sulfide minerals exhibit semiconductor properties (Marsden & House, 2006). Therefore, the contact between constitutive sulfide minerals inside complex sulfurous ores entrains electrochemical phenomena in which sulfide dissolution is a genuine corrosion process (Azizi, Petre, Olsen & Larachi, 2010). For instance, galvanic interactions could be initiated between the various constituents within the ore and could substantially increase or decrease the reactivity of some of the associated minerals."

Jan 1, 2012

By Eric Johnson

"IntroductionHistoricalCyanidation is a leaching process, in world-wide use, to extract gold (and silver) from ores and concentrates. The process has many inherent advantages on account of its adaptability:a. to any scale of operation;b. to a wide range of ore types and mineral associations;c. to a wide range of physical characteristics of the gold particle size, alloy (electrum) or mineral (telluride);d. to relatively simple plant controls and operating procedures;e. to simple marketing procedures and quick cash return.The basic idea for cyanidation was first described and patented by a German chemist, L. Elsner, in 1846. Some forty years later, J.S. McArthur, a metallurgical chemist and R.W. and W. Forrest, medical doctors, all of Glasgow, Scotland, came to realize the import of the discovery and accordingly, registered patents in Great Britain in 1887 and in the United States in 1889. The keystone of the McArthur-Forrest patent registration was the use of weak (0.05o/o) instead of strong (1.0%) solution.The years 1890-1910 saw much progress in equipment design and the advance from batch to continuous processing to increase efficiency and reduce operating costs.In later years, technological progress followed advances in materials of construction and control systems. Current innovations include large-scale equipment, high-capacity thickeners, belt type filters and Steller, candle-type filters for plants using zinc dust precipitation. As well, environmental protection is increasingly a major concern.The technology of gold adsorption from cyanide solution onto activated carbon has made rapid strides in recent years. This has followed the initial efforts of Potter, Salisbury, Zadra and their colleagues of the U.S. Bureau of Mines Research Station in Salt Lake City, Utah, and the field work of Homestake Mining Company personnel, in Lead, South Dakota."

Jan 1, 1989

By E P. Graham

Orebodies occur in an infinite variety of grades, shapes and sizes, and take many millions of years to grow. When extraction starts there is only one possible end -the mine sooner or later will run out of ore and shut down. If the mineral industry is to supply the ever increasing demands of modern civilizations, more and more metals must be found and mined. This will require a never-ending search for ore, and the development of every economic body, large or small. To justify the mining of a small orebody, it first of all must pay its way. If the size of the burden imposed by the capital cost estimates is not carefully worked out, an otherwise promising situation could be killed. The very nature of mining, as a transient industry, re-leases a steady stream of good used equipment, and the trained personnel to install and operate it. All manner of plans and layouts, which can be utilized at a new property, are available. Working these and other economies into the estimates will sometimes make enough difference to give a prospect the green light.

Jan 1, 1964

By F. Mohamm

"Recent changes in regulations and scientific advances concerning selenium bioaccumulation have placed greater importance on non-biological treatment systems for selenium control. Mining wastewater contains hexavalent selenium (selenate) as the predominant aqueous species and possibly small amounts of tetravalent selenium (selenite). Non-biological removal of selenite is accomplished readily and cost effectively by ferric co-precipitation and adsorption using ferric oxyhydroxides sourced from ferric salts or iron anodes in electrocoagulation cells. Selenate on the other hand is difficult to remove. It is often incorrectly assumed that electrocoagulation is suitable for removing both selenite and selenate. Selenate removal efficiency by electrocoagulation is low and the amount of waste residue produced high. In contrast, BioteQ’s Selen-IX™ process removes selenate very efficiently and produces a much smaller amount of stable residue. The process combines selective ion exchange with electro-reduction of selenate in electrocells that physically resemble electrocoagulation cells but are designed and operated differently. This paper summarizes four years of pilot scale demonstration on a wide range of mine waters and discusses the key benefits and limitations of Selen-IX™. The pros and cons of combining ion exchange with electro-reduction in comparison to direct electro-reduction of selenate are also reviewed.INTRODUCTION Selenium in Mining and Mineral Processing Effluents Similar to sulphate and metals, selenium presence in mining and mineral processing wastewater originates from minerals contained in the mined deposits. Therefore, no organoselenium species are typically present in these kinds of waters and inorganic species including selenite (SeO32-), selenate (SeO42) and elemental selenium account for the majority, if not all, selenium present in these streams. Elemental selenium is not always present in mine water but is often contained in smelter wastewater. To comply with new environmental regulations, a successful water treatment plant must remove selenium from all these forms effectively and economically without generating by-products that are difficult to dispose of or manage. Elemental selenium can be dealt with using filtration or gravity separation in clarifiers often assisted by flocculants and/or coagulants. Mine impacted waters typically contain other forms of suspended solids which are removed from water in this way. Once the solids are removed, the selenium species that remain untreated are the dissolved forms. In mining waters this is mostly selenate with small fraction of selenite. In smelter wastewater, the majority could be selenite. It is well established that tetravalent selenium is readily removed from water by using ferric iron co-precipitation at pH > 4 (NAMC SWG, 2010). Ferric hydroxide/ferrihydrite solids act as the adsorbent for tetravalent selenium when it is in one of the ionic forms of biselenite or selenite. This treatment for tetravalent selenium is highly efficient. Therefore, tetravalent selenium removal is generally not an issue and is often easily incorporated into lime neutralization or unit operations such as electrocoagulation used for removing other metals present in mine impacted waters. Another option of dealing with tetravalent selenium is sulphide precipitation in acidic pH which produces SeS2 and can separate selenite from other metals and/or sludge produced at neutral to alkali pH."

Jan 1, 2017

By F. S. Thurner

"This paper describes the engineering and construction activities of the ""design-build"" project awarded to the joint venture of Foundation-Comstock-Janin for the construction of the plant and wharf facilities, camp site, power plant and all supporting services. As a member of the Foundation Group of companies at that time, Fenco actecl as consulting and design engineers for the project. Particular emphasis is given to the problems which adversely affected design and construction activities due to prevailing arctic conditions and the remote location of the project. The paper also describes the approach taken in the investigation of the site and soil conditions as well as the selection of the special structures for the 225,000-toncapacity fibre storage building, the wharf structure for 50,000-dwt vessels, and the 1,000-tph-capacity reclaiming and ship-loading facilities . It further covers the logistics problems and the scheduling activities related to the short duration of the shipping season, and the transportation of equipment and mate1•ials by sea as well as by air."

Jan 1, 1976

By S. A. Bunk, E. C. Eccleston, J. J. Amsden

Fluidized bed technology has been widely applied to mineral and metallurgical processes. Over the years, modeling of fluidization technology has progressed to a level at which basic design parameters can usually be defined based on empirical correlations. In addition, scale-up considerations have become better understood, and significant advances have been made in the area of computer simulation. Despite these advances, fluidization is a complex phenomenon, and modeling tools remain limited in their ability to simultaneously model both fluidization and chemical process parameters. As a result, almost all mineral and metallurgical applications of fluidized bed technology require pilot testing prior commercial scale design. This paper outlines pilot plant testing requirements and process development considerations for development of low technical risk commercial designs.

Jan 1, 2011

By P. Hanniala, S. Harkki, B. Andersson

"The Outokumpu Flash Smelting Process was put into commercial operation in 1949. The original process was based on the use of preheated air. The adoption of oxygen enrichment of the flash smelting process air in 1971 was a crucial improvement, especially for smelter capacity. Oxygen use according to the Outokumpu method means selection of the most suitable oxygen content for the process air on the basis of the concentrate composition, capacity and matte grade. The furnace is not bound to only one fixed degree of process air oxygen enrichment; the oxygen content may vary from 21% to 100%.The degree of oxygen enrichment and the matte grade are the most important process parameters in reducing the operating costs of the whole system, including smelting, converting and acid production. Raising the matte grade allows more efficient use of the reaction heat in the smelting stage. Sulphur is recovered in a high-strength, constant-flow gas stream. The blowing time in the converters is reduced considerably.Oxygen enrichment and high matte grade improve the energy efficiency of the plant complex as long as the surplus heat from the system is not wasted. When the operating costs and investment expenditure of the total plant complex are taken into account, a reasonably high degree of oxygen enrichment (35-80°/0) is the best alternative in practice. Existing operating smelters have achieved single-stream thoughputs of over one million t/yr of concentrates.HistoryLocal capital and operating costs as well as lower energy consumption per unit of metal produced are now the crucial factors in determining the choice of process. In the late I940s, the same reasons prompted Outokumpu to develop the original flash smelting process in Finland. Between 1900 and 1940, very few technical changes in pyrometallurgical copper production took place. However, the commercial use of the flash smelting technique began a new era in metal extraction from sulphide concentrates. The characteristic feature of the method is that the concentrate is smelted in suspension: this offers the most favourable conditions for heat and mass transfer, and thus high reaction velocities. Outokumpu was the first to exploit the known advantages of flash smelting in a commercial installation at Harjavalta in 1949."

Jan 1, 1982

By Raj Thamburaj

"Over the last few decades, the emphasis on affordability and reduced cost of ownership has necessitated the development of innovative processes to carry out repairs in aero engine components. Conventional weld and braze repairs have evolved into advanced, sophisticated processes using state of the art knowledge in lasers, robotics and materials technology. This paper illustrates past and present scenarios in an attempt to illustrate progress that has been made in this area. The problems encountered in the past have been detailed along with the solutions that have been developed and commercially implemented to address these issues. Apart from technical progress, this presentation also addresses the progress made in business approaches and in Certification/Regulatory issues surrounding aero engine repair. Progress in Technology Repair technologies have also been the embryo from which new and revolutionary manufacturing technologies have evolved as well. Electron Beam Free Forming and LENS are examples of how a completely new manufacturing concept can evolve what was originally only a process to join metals. The current and future potential of these spin offs is discussed providing examples of application. While several problems have been solved over time with the implementation of advanced repair technologies, the demands of the industry have created new challenges. The paper describes these issues, outlines potential solutions and discusses the future of repair technologies in terms of the far reaching influence it is sure to have in design, manufacturing, maintenance management and life extension. Progress in Business Trends.Business approaches to repair and maintenance have also gone through considerable change with the introduction of ""Power by the Hour"" and other similar arrangements between the companies responsible for engine overhaul and the end-users. Program Based Logistics (PBL) is yet another innovation to provide a win-win situation for the repair service provider and the end user. This paper traces the development of these business initiatives and highlights successful applications. Progress in Repair Certification, Regulatory Issues.Understanding of the issues surrounding certification of repairs has also evolved with time and regulatory issues have been clarified considerably. Procedures for analysis and testing are much clearer and ""Check Lists"" are being drafted for certifying repairs on various engine components. The PMA phenomenon has added yet another dimension to the issues regarding certification and these are discussed as well."

Jan 1, 2010

By G. Stafford Whitby

N ATURAL gas is found in several provinces of Canada, particularly Ontario, New Brunswick, and Alberta. The largest producer is Alberta, and there the most important field is the Turner Valley, where some low-gravity crude oil and naphtha are associated with the gas. Last year there was produced from the Turner Valley field an average of 3,462 barrels, or about 450 tons, of oil a day. The gas flow from the wells in this field bears such a high ratio to the oil which comes from them that, despite the enforcement of a measure of conservation, it amounted to the vast quantity of 6,000 tons a day, or more than 2,000,000 tons a year. Prior to the application of any conservation measures, the gas flow was at one time of the order of 12,000 tons a day. The heat content of one ton of the gas is almost equal to that of two tons of coal. A certain amount, say, 10 per cent," of the gas is used in Calgary and surrounding towns and in re-pressuring the Bow Island gas field, but the greater part of it goes to waste. What are the possibilities of making use of this waste gas, in whole or part? The possibilities of using it profitably as fuel for domestic and industrial purposes have undoubtedly been carefully considered by the Company which now distributes a part of the gas to cities and towns in Alberta. But the relative sparness of the population and the cost of pipe lines makes such possibilities strictly limited. There are, however, distinct possibilities of making use of at !east a part of the gas for the production of a variety of chemical products and of liquid motor fuel. The present paper is devoted to outlining some of these possibilities. About three-quarters (by weight) of the Turner Valley waste gas consists of methane, the lightest and, chemically speaking, the simplest of hydrocarbon gases. The remaining quarter consists of heavier hydrocarbon gases-ethane, propane, and butane. Formerly, naphtha was separated from the well gas by a simple process of self-refrigeration. The gas coming from the wells at a pressure of, say, 1,200 to 1,800 lb., was passed through simple cylindrical vessels fitted with baffles and known as 'separators'. The pressure was allowed to drop to, say, 300 lb. in the separators, and the cooling effect secured by this expansion brought about separation of the naphtha. The naphtha thus obtained was 'wild', that is, it had a high vapour pressure owing to the presence in it of dissolved and liquefied gas. In order to reduce the vapour pressure to a level at which the naphtha could be shipped, this gas was removed either by distilling it out through a 'stabilizing' column or, according to the practice at many wells, merely by allowing the naphtha to 'weather' in open tanks (heated by coils if necessary) until the gas had been driven off in to the air.

Jan 1, 1936

By P. H. Riordon

ONE OF the major sources of the world's supply of asbestos lies in a belt of ultrabasic rocks stretching through the Eastern Townships of Quebec where chrysotile asbestos has been mined continuously since 1878. The productive portion of the belt extends from the town of Asbestos in Shipton town-ship northeastward some 60 miles to the eastern edge of Broughton town-ship. (See map). Twelve mines, currently treating an aggregate of over 60,000 tons of rock daily, produce more than one million tons of asbestos :annually. An equal number of mines are now dormant, having for the most part exhausted their reserves. It is evident from the past and present activity, in this belt that it can look forward to at least half a century or more of large scale production. The host rock to the asbestos de-posits is essentially a peridotite which originally contained I 0 to 15 per •cent pyroxene. The peridotite, associated with dunite, pyroxenite

Jan 1, 1962

By Mike Fontaine

The success of a project is defined by meeting the financial performance objectives of the business case within a stipulated timeframe. Early in design, little information is normally available; the uncertainty introduces risk to the project outcome. Using a range of risk management tools and techniques, a project can be developed from front end loading phases 1 through 3 (FEL1–FEL3), and project implementation (FEL4) and then into operations with an optimized probability of success. For every project element, the risk management framework embodies: establishing a context; assessing risk (identify, analyze, and evaluate); and treating risk. Embedded within design activities, this process mitigates or eliminates risks. Monitoring and control, as well as extensive communication and consultation with stakeholders, is integral to the risk management process.

Jan 1, 2015

By A. P. Schissler

Mining has several characteristics, uncommon in other business sectors, which pose additional challenges to the implementation or design of IT and management systems that use the information. Understanding these characteristics would improve the chances of successfully importing new information technology and management techniques to mineral producers. The most important characteristics that should be understood are workplace issues, the industry’s dual nature of being a continuous construction project using cyclical factory processes, labour challenges, workplace culture, information availability, integrative data elements, and the current technical education of mining engineers. These characteristics were taken into account in two applications of information technology and systems design at operating companies. The research and consulting projects focused on the development of an IT-enabled performance management system at several underground metal mines in Canada and an integrated data warehouse for surface mines spread throughout the United States and Latin America.

Jan 1, 2006

By R. Gallinger, B. Kelley

"In 1997, a group of Canadian mining companies met to review the Mine Environment Neutral Drainage (MEND) program and to consider future activities. They concluded that (1) that Canadian industry and Natural Resources Canada (NRCan) should fund a small secretariat in Ottawa to support technology transfer in Canada and, (2) that it was important for industry to continue the momentum of MEND on an international scale.The need for the International Network for Acid Prevention (INAP) was strongly endorsed by consultants, company, university, and government experts from Australia, Canada, and the United States who convened in Vancouver in February 1998. The initial focus was the development of a solid knowledge base covering the collective experience of INAP’s members to promote the dissemination of successful practices, the identification of knowledge gaps, and the formulation of effective research proposals. The sharing of information on past successes and failures alone was viewed assufficient justification for the formation of INAP.INAP was officially launched in October 1998, and is now an effective, industry-based initiative to globally coordinate research and development in the management of sulphide mine waste. Significant improvements in the management of sulphidic mine materials through knowledge sharing, research, and development of technology by INAP will reduce liability associated with acid drainage.This paper will explore the international efforts and activities of INAP."

Jan 1, 2005

By R. Gallinger

In 1997, a group of Canadian mining companies met to review the Mine Environment Neutral Drainage (MEND) program and to consider future activities. They concluded that (1) that Canadian industry and Natural Resources Canada (NRCan) should fund a small secretariat in Ottawa to support technology transfer in Canada and, (2) that it was important for industry to continue the momentum of MEND on an international scale. The need for the International Network for Acid Prevention (INAP) was strongly endorsed by consultants, company, university, and government experts from Australia, Canada, and the United States who convened in Vancouver in February 1998. The initial focus was the development of a solid knowledge base covering the collective experience of INAP?s members to promote the dissemination of successful practices, the identification of knowledge gaps, and the formulation of effective research proposals. The sharing of information on past successes and failures alone was viewed as sufficient justification for the formation of INAP. INAP was officially launched in October 1998, and is now an effective, industry-based initiative to globally coordinate research and development in the management of sulphide mine waste. Significant improvements in the management of sulphidic mine materials through knowledge sharing, research, and development of technology by INAP will reduce liability associated with acid drainage. This paper will explore the international efforts and activities of INAP

May 1, 2005

Why innovate? ? How are we doing in Canada? ? How can we do better? ? Why now? ? What?s next? ? Lowering production costs ? Improving productivity ? Increasing value-added ? Discovering new mines, extending life of existing ore bodies ? Reducing environmental footprint ? Improving health and safety

May 1, 2008

By J. Budac, R. Krentz, P. Cordingley, G. Freeman, M. E. Chalkley, H. Scheie

Pressure hydrometallurgical unit operations have been in commercial use at the Fort Saskatchewan refinery of Sherritt International Corporation for fifty years. This paper traces the history of Sherritt from its origins in northern Manitoba, and the development of the first hydrometallurgical nickel-cobalt refinery in 1954, utilizing pressure hydrometallurgy, to the modern day refinery. Sherritt's involvement with pressure hydrometallurgy during the past 50 years has included the operation of the refinery, the development and licensing of technology, incorporating pressure hydrometallurgical unit operations, to more than 30 companies worldwide, the joint venture at Moa, Cuba involving both leaching and precipitation at elevated temperature and pressure, and the production of specialty metal powders. Developments in each of these areas are reviewed.

Jan 1, 2004

By W. L. Murphy

The Star Lake property, located 115 km northeast of La Ronge, Saskatchewan is underlain by metamorphosed andesitic tuffs and flows which have been intruded by the dioritic to granitic Star Lake Pluton. Gold mineralization on the Star Lake property was first discovered at Ru h Lake by E. Beveridge in 1959 and by M. and E. Hird in 1961. In 1960 E. Partridge discovered Kahn 18 and Kahn 28. In 1982 the SMDC-Starrex joint venture completed geophysical and geochemical urveys including magnetics, VLF, IP/Resistivity, vegetation, bulk till and oil sampling, followed by drill testing of pecific targets. To date the most ignificant depo it is the 21 Zone which contain drill indicated reserves of 230,000 tons grading 0.5 oz/ton Au . The 21 Zone con ists of quartz with 5-10% (locally > 30%) drusy pyrite, minor chalcopyrite and trace amounts of scheelite, chalcocite and arsenopyrite. The 21 Zone is enclosed by a 25-50 m wide band of mylonitized monzonite. The mylonite occurs in the central portion of a 300 m wide northeasterly trending zone of brittle deformation .

Jan 1, 1986

By Jon A. Carlson, W. Scott Williams

The EKATI"" Diamond Mine commenced operation in October 1998. It is operated by BHP Diamonds Inc., which is a part of the Non-Ferrous and Industrial Materials Division of BHP Minerals, a business unit of BHP Company Ltd. of Melbourne, Australia. The EKATI"" Diamond Mine is a joint venture of BHP Diamonds Inc. (51%), Dia Met Minerals Ltd. (29%), Charles E. Fipke (10%) and Dr. Stewart L. Blusson (10%). In December 1993, an office was opened in Yellowknife, Northwest Territories specifically for the then Northwest Territories Diamonds Project (EKATI"" Diamond Mine) development. EKATI"" Diamond Mine is located 300 kilometres northeast of Yellowknife and 200 kilometres south of the Arctic Circle in the Northwest Territories of Canada (Figure 1 ). The site is located in a remote tundra area of continuous permafrost, north of the tree line, which is part of the Canadian Shield. Wekweti (Snare Lake), a Dogrib community approximately 180 kilometres southwest of the project, is the closest neighbour. The mining area and facilities lie within the 10 960 hectares land leases held by the joint venture. The total claim block (core zone and buffer zone joint ventures) covers 344 000 hectares. To date, more than one hundred kimberlite pipes have been identified within the claims. Five of these provide the basis for the present mine plan. Total capital investment in the project is over C$700 million. At full production employment will be about 600, including employees and long-term contractors, with over 33% being Aboriginal from the Northwest Territories.

Jan 1, 2001

By Doug Russell

Natsource: At a Glance l 160 employees l Global reach ? New York, Washington, Calgary, Ottawa, Toronto, London, Tokyo l Major Environmental Commodity Broker ? Rated as Top GHG Broker (Environmental Finance Magazine Survey, Dec. 2000 & 2001) ? Leading RECs Broker ? Large Broker of SO2, NOx l Large Energy Broker ? One of Highest Volume Gas Brokers ? Major Electricity Broker Overview l International Market l Implementing the Rate-Based Proposal l Assessment and Management of Risk from GHG Emissions Limitations

Nov 1, 2002

By C. H. Attwood

Introduction In presenting this paper on the water-power resources of the Province of Manitoba, it was considered that a brief resume of the power resources of Canada, of the power already developed, and its utilization in the industries 9f the country, would be of particular interest in showing the rapid progress that has already been made. Amongst Canada's national assets, water power occupies a foremost place because of the facilities it provides for the development of her other great natural resources. The rapid development of the mining, pulp and paper, and general manufacturing industries, and the concomitant growth in urbanization, with its numerous demands for domestic, commercial, and municipal service power, have combined to stimulate hydraulic development to a point surpassing even the most sanguine predictions of a few years ago. With the bringing into operation during 1928 of hydraulic turbines aggregating over 550,300 h.p., and of a further 378,400 h.p. in 1929, Canada's total hydraulic development at the end of 1929 amounted to over 5,700,000 h.p., and in this year, 1930, the active construction in hydro-electric plants throughout the country totals in excess of 1,600,000 h .p.

Jan 1, 1930