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By J. R. del Castillo, J. Ruiz, N. Kuyucak, J. Chavez

Environmental Impact Assessment (EIA) and Feasibility Studies (FS) were carried out to evaluate the potential use of treated acid mine drainage (AMD) occurring at the Kingsmill Tunnel in the Central Andes of Peru. The 11-km long tunnel drains the underground works of the Morococha Mining District and discharges about 1.25 m3/sec of AMD directly into the Yauli River, which is located within the Amazon Basin. The communities living downstream cannot use the Yauli River water due to its low pH and elevated concentrations of metals (e.g., Cu, Zn, Fe, Mn, As, Cd) and sulfate. Studies carried out for this project included technical feasibility, EIA, economic viability and social impact assessment phases. During the "Technical Feasibility" phase, the treated AMD was produced by simulating a high density sludge (HDS) lime neutralization/precipitation process and was evaluated for various potential uses. Mining companies located in Morococha, in particular Centromin Peru S.A., and the Water Works Company of the City of Lima (Sedapal) collaborated with Golder Associates during the studies. The Canadian International Development Agency (CIDA) provided the financial assistance. The results of the physical, chemical, biological and toxicological analyses demonstrated that the treated AMD could be used for supplementing the drinking water supply of Lima and for agricultural (e.g., irrigation and livestock) and recreational purposes. Process design and scale-up parameters were also determined for the implementation of the full-scale treatment facility to the site. The use of the treated AMD as a drinking water supplement would be economically feasible.

Jan 1, 2004

By Robert B. Parsons

"The new Ontario Liberal government introduced its first budget in October. The changes to The Mining Tax Act proposed in the budget are mean t 10 simplify the current system without any loss of revenue to the government. It goes without saying that some operators will benefit from the changes while others will pay more taxes after 1985.With regard to ongoing matters at the federal level, the proposed carve-out legislation and the issue of northern allowances are being discussed with government officials, and a small victory has recently been scored with regard 10 the laxation of certain share transactions of prospectors and grubstakers. A report on these issues is provided herein.Ontario BudgetOn October 24, 1985, Ontario Finance Minister Robert F. Nixon tabled a budget proposing several significant changes to both the Ontario Mining Tax Act and the province’s income tax legislation.Mining Tax ActA flat rate of tax and reduced processing allowances highlight proposed changes to The Mining Tax Act. The proposed changes, with a comparison to the existing system, are set out in Table I.The most significant change is the replacement of the graduated tax rate schedule with a flat 20010 tax rate. This is a welcome change for most mine operators who viewed the high rate of 30% on profit over $20 million as counter-productive.However, the flat rate of ta x may not be welcome to all operators. Generally speaking, operators with less than $ 10 million annual profit are better off under the graduated rate system, while operators with annual profit exceeding $10 million will benefit from the 20010 tax rate."

Jan 1, 1986

By S. Leong

This paper reports on research examining disclosures from mining companies regarding their water usage in the Macquarie and Lachlan catchment areas, both parts of the Murray-Darling Basin in New South Wales, Australia. The objective of the research was to assess whether this disclosure is sufficient to allow communities to determine whether mining companies are complying with mining conditions of consent and abiding by the requirements of their water licencing agreements. These requirements are then compared to the water reporting requirements of the Global Reporting Initiative (GRI) and the Water Accounting Framework for the Minerals Industry (WAFMI). Communities are concerned about whether the mining industry?s use of water will have impacts on their livelihoods and lifestyle and thus require information concerning the quantity of water that will be extracted, how much water will be left for other stakeholders and whether the mining will affect water quality. This is an archival study. It has involved examining relevant publically available information released by mining companies and government regulators and determining if this is sufficient to meet the needs of the local communities. Additionally, it has involved looking at information indirectly provided by mining companies, via the use of intermediaries. Further, information availability concerning basic water accounting and regulatory breeches and whether such information is available at the mine site level has been considered. It is found that while NSW legislation places very little reporting requirements on mining companies, the development consent conditions for new projects and extensions to existing projects are quite significant and should be sufficient to meet the needs of local catchment residents though such information is not always easily accessible for the layperson.

Aug 1, 2013

By K. Sasaki

Ventilation measurements were carried out in a shallow underground-quarry space with relatively large internal volume of 14,600 m3 in order to evaluate its effective ventilation characteristics. Based on air velocity measurements with an ultrasonic anemometer in the exhaust airway connected to the space, it was found that the space was ventilated by natural ventilation airflow with intermittent changes in direction. It was difficult to measure the ventilation flow with typical methods of flow measurement provided from the intake portal and throughout the mine, because the cross-sectional area and volume of the openings were too large and the flow was variable. In the present study, a tracer gas method was applied to evaluate the effective ventilation airflow rate in the space. A photo-acoustic infra-red gas monitor, highly sensitive to SF6 gas used as a tracer gas, was set in the space to determine air exchange rates from gas concentration-time decay curves. The seasonal variations of airflow and thermal environment in the space were investigated through 13 sets of measurements taken over 15 months. Airborne rock dust concentrations were also measured at same time in the opening. The correlations between the effective ventilation airflow rate, thermal environment and dust concentrations in the opening space were analyzed and are discussed based on the presented measurements taken during year. It is concluded that seasonal variations in effective ventilation flow and the dust concentration are mainly due to differences in air temperature in the space, as affected by the rock?s surface temperature and atmospheric temperature. In summertime, the air temperature and associated air density difference generated lower natural ventilation flows resulting in higher dust concentrations.

Aug 1, 2013

"In today’s world of complex projects, where engineering and execution are supported by a high level of project management and systems, how critical is the human factor in design engineering. Based on his involvement on a variety of projects, Tony Lipiec will relate his experiences as the impact of 4 factors: the ‘team’ involved in the design and execution of the project; the project and information systems supporting the project; the impact of scope, time, and budget; and finally the selection of the proper success criteria to judge the project and the people who have enacted the project.The discussion of the team will relate to the quality of people and the impact of their knowledge, attitude and experience. It will also look at the relationships and interests of the various stakeholders. Decision making and taking responsibility will be discussed.Supporting the team are the management, document and information systems. The value that these systems bring to the project as a whole will be examined. How project size impacts the applicability of the systems will be discussed.Scope, time and budget are recognized as critical. Reference will be made to the interplay between these components which are vital to project success. The issue of iterative design and whether it is necessary will be considered together with the development of supporting technical information.Finally the selection of the proper success criteria and the awards provided to the team can have a big impact on the final, production success of the project. The author will discuss his views on the impacts of these on EPCM projects."

Jan 1, 2016

By Y. A. Grinin, M. A. Liamina, V. A. Shumskij, Y. I. Sannikov, M. V. Radashin

"A brief history of the development of the Kivcet flash smelting process is presented. The broad scope of the process with an ability to treat high grade lead sulphide concentrates, as well as oxidized lead-zinc residues, is emphasized. Fine coal in the charge serves two purposes, one as auxiliary fuel and the other as a pre-reductant for ferric iron in residues. Current Kivcet operations incorporate a layer of coke or “coke checker” at the surface of the slag in the reaction shaft that acts as a reducing agent for flame products or slag that flow through it. Details of this invention, are given. IntroductionFor many years, the sinter-blast furnace lead smelting process has been the main internationally accepted method used for the production of primary lead metal. In recent times, this process has been unable to meet legislated environmental restrictions and it became clear in the mid-1960s that a new and cleaner process would have to be developed. The present level of Kivcet performance was developed in three main stages:1. flash smelting natural sulphide lead raw materials with the attached electric furnace for production of lead bullion and crude zinc;2. natural raw material smelting with lead and zinc separation in a “coke filter” or “coke checker” at the surface of the slag in the reaction shaft to produce lead bullion and ZnO-bearing slag that can be fed to conventional slag fuming; and3. processing of oxidized lead-bearing raw materials, such as low grade zinc plant residues, with the production of lead bullion and ZnO-bearing slag periodically directed to slag fuming."

Jan 1, 1998

By Gordon Sparks, Lyle Kajner

"An often over-looked component in the assessed value of a mining property is the value derived from the ability of the operator to limit financial losses during adverse economic times (i.e. low market price, high energy prices, etc.) by suspending operations. Overlooking the value of this type of operating flexibility when conducting mine investment analysis may negatively bias the risk profile for the investment by over estimating the investment's downside potential, thereby effectively undervaluing the investment. This paper illustrates the nature of the value of operating flexibility and discusses how it may be explicitly quantified within the context of conducting stochastic mine investment analysis. IntroductionMining properties are evaluated using an array of techniques ranging from simplistic non-discounted payback calculation s to sophisticated, discounted-stochastic simulation. Stochastic simulation analysis is perhaps the most robust mine investment analysis technique as it not only provides an estimate of the expected value of the property, but also quantifies the associated risks (for examples of stochastic mine investment analysis, see: Billingsley and Yaychuk, 1986; Gentry and O'Neil, 1984; Munro, 1977; or Harris, 1970).The quantification of risk is important as it provides the necessary yardstick required to allocate the corporation's resources efficiently. Resources are said to be allocated efficiently when the corporation's expected long-term financial reward is maximized while at the same time minimizing its risk (see Hertz, 1968; or Markowitz, 1952 for in depth discussions on efficiency as it relates to investment policy). The efficient allocation of resources should be the objective of any rational corporation. Therefore, rational corporations should employ stochastic evaluation techniques when screening their investments."

Jan 1, 1992

By Y. P. Wu

Steeply dipping seam refers to the coal seam with dipping angle in the range of 35?55°, which is well recognized to be very hard to mine by the mining industry all the world. In the last two decades, some fundamental researches were focused on the strata behavior of long-wall panel, complicated rock mass breaking process of the steeply dipping seam, overburden stress field developing and evolution, rock strata breaking and moving process, rock structure stability mechanism and control. Results show that it?s presenting macro stress arch-shell (MSAS) of the stress distribution of the overlying rock in steeply dipping seam. The MSAS is the spatial distribution of intensity envelope line under the strength criterion and has the geometry shape asymmetry as well as the stress distribution heterogeneity. The arch- shell base will forward as the working face mine forward and the shell roof will extend to higher overlying strata above the gob. In this paper, the stress arch-shell analysis model and coordinate system were established and analyzed the inclined masonry structure at different zone. Analysis results show that the rock damage at the key part of the arch-shell is the main factor which causes whole overlying rock structure failure. The rock structure instability modes have tension instability of the shell roof, compression-shear instability of the shell shoulder and composite instability of the shell base, meantime, instability coefficient is proposed to determine instability condition. The above research results enrich the complex coal seams mining theory and provide a theoretical basis for mining safely and efficiently in steeply dipping seam.

Aug 1, 2013

By G. R. Guillet

"Bricks made from local Paleozoic shales, and floor and wall tiles made from imported clays, both established record production volumes in 1985 and are the strongest segments of Ontario's clay products industries. However, renewed interest in traditional materials also supports a good market for clay flower pots and flu e liners, and innovative processing studies are showing promise for possible new production of clay roofing tiles. This paper reviews the highlights of a comprehensive study of Ontario's clay products industries, completed in 1986. IntroductionFor some years now, Ontario's clay products industries have been unspectacular in their attempt to cope with the recent recession and the impact of alternative materials. But a strong demand for bricks in recent years has done much to dispel the gloom. Bricks, drainage tiles, sewer pipes, flue liners, structural and partition tiles, and flower pots have been commonly referred to as ""heavy"" clay products, and they have been based largely on local clays and shales. To this list might be added expanded aggregate and mineral wool. Clay refractories, sanitary ware, electrical porcelain, art pottery, and floor and wall tiles are not considered heavy clay products, and are commonly made from a variety of ceramic materials, many of which are imported.Production facilities for heavy clay products often began in Ontario as small family enterprises, using whatever clay was available locally to supply the local market with building bricks and other clay products needed for construction. Improved road systems increased the market range for these plant s, and new technology and industry standards resulted in gradual upgrading and consolidation of them as traced in Table I"

Jan 1, 1988

By William H. Pomroy, Kenneth E. Hjelmstad

An underground mine fire can seriously threaten the lives of all personnel in the mine. This fact makes fire emergency planning a high priority in the mining industry. A fire emergency plan includes a means of warning miners of the existence of a fire, and the need to evacuate or retreat to a place of refuge. The warning alarm must be fast and must reach all miners, regardless of their location or work activity. Means of fire warning are varied, and include such methods as stench, flashing lights, telephones, and word-of-mouth (messengers). Unfortunately, none of these methods are entirely satisfactory. Stench can be slow and seldom achieves total mine coverage, especially in high-back room-and-pillar mines with low ventilation velocity. Telephones are effective only where personnel are close enough to hear the phone ring. A novel fire warning alarm system has been developed by the U.S. Bureau of Mines which enables instantaneous warning of all underground personnel. The warning alarm is sent by an electromagnetic signal which penetrates through mine rock from a transmitter to small person-wearable receivers. Each miner's cap lamp battery could be equipped with a small receiver and when a fire or other emergency occurs the miner could be alerted to the danger by a blinking of the cap lamp. Testing of prototype equipment has demonstrated that the transmitted signal is capable of penetrating through over a mile of mine rock and activating the receiver. This paper describes the theoretical basis for through-the-rock ultra-low frequency electromagnetic transmission, design of the prototype transmitter and receiver, test results, and status of commercial development of systems utilizing this technology.

Jan 1, 1994

By Lorant B. Geller

Sixteen miners died tragically at the Paymaster gold mine at Timmins, Ontario in February, 1945, when a badly corroded hoist rope broke. The investigation of the Royal Commission that followed arrived at a number of recommendations (Investigations, 1947) aimed at avoiding future disasters of this kind. One consequence was the development, and legislated use in Canada, several decades ago, of powerful electromagnetic (EM) instruments for the nondestructive testing of mine shaft wire ropes. The authors have been involved for many years in the design, production, and testing of EM instruments (Geller and Udd, 1990 and 1992, Geller and Kitzinger, 1991, Geller et al., 1993). Since the mid-1990s particular attention was paid to the design and operational results obtained from the computer- controlled portable MagnographJ II wire rope tester (Geller et al., 1995 and 1998). In the present article the authors summarize further hardware- and software-related developments of this instrument. Further, an account is given of the results obtained from the most recent design known as the PermaScanJ testing system. This is also a computerized dual-function system. In it, however, the sensor head is designed primarily, if not solely, for permanent installation and for remotely controlled operation. This represents a basic departure from traditional designs, which were intended for ad hoc temporary installations. The remotecontrolled instrument described in this paper has now been in operational use for more than 4 years.

May 1, 2003

By Roy EI. Durr, Glen R. Davidge

"This paper presents the results of structural analyses and full-scale destructive tests conducted on liner plate culverts. The purpose of this work was to establish a design method and evaluate the suitability of using these structures in potential roof-fall areas for a rehabilitation application in lower stress and relaxed mining environments. Field evaluation of the design is currently in progress.Theoretical ultimate resistance functions were established for two different culvert shapes and were found to be representative of their experimental behaviour. The ultimate resistance function was used to determine their plastic behaviour to a rapidly increasing deflection condition, to determine the energy absorption capacity of these structures, and to predict their response to impact loading.IntroductionThe Kidd Creek mine of Falconbridge Limited is located justnorth of Timmins, Ontario. The area under rehabilitation for which this program was developed is the 2600 level of the No. I mine. The problem of effectively securing selected drifts at the 2600 level in NO.1 mine, for access to a high-grade ore block, is key to the economics of the operation. Diamond drill test holes had indicated a loosened rock mass above the 2600 level of about 7.5 m thick in response to the extensive mining operation below this level. This level forms the arbitrary boundary between the No. I and No. 2 mines, and has extensive volumes of cemented rock fill below it and largely untouched ore above it to the 2000 level in the North orebody. The walls at that level were showing relaxed ground conditions typical of de-stress: sub-horizontal joints opening up, and peeling.Due to the ground conditions, the consequent safety risks, the high grade of the ore, the potential production delays, and the likelihood of several phases of rehabilitation, regularly used drift rehabilitation employing rock bolts, cable bolting, or shotcrete was not practical. Two options were deemed possible alternatives to suit these conditions, steel sets with blocking and lagging, and liner plate culverts with backfill. Culverts were chosen."

Jan 1, 1995

By D. J. Bowen

"The Great Dyke extends for 540 krn along strike, to unknown depth, and varies in width from 3 krn to 11 krn. Rb/Sr age determinations gives values of approximately 2470 Ma.The Dyke consists of a variety of mafic and ultramafic rocks, many altered to serpentinites. These include, from top to bottom, successions of gabbro/norites, pyroxenites, peridotiteslharzburgites, and dunites/picrites.The layers dip in from either margin, steepest at the edges (20°) and flattening toward the central sections. Four separate complexes are present. From north to south these are termed the Musengezi, Hartley, Selukwe and Wedza Complexes, and are described as 'boat-shaped' or 'pig-troughed'. All are similar in petrological sequences. Physiographically, the Dyke is spectacular in the north, where as a mountain range it meets the Zarnbezi Escarpment. Elsewhere in the central parts there is little surface expression and wide open treeless vleis. Dyke rocks cut through granite and schist belt terrain and are termed 'The Magnesia Belt'.Vast mineral resources exist. These include chrome, asbestos, platinoids, nickel, copper and gold. Up to eleven chrome seams numbered from top to bottom occur in the lower ultramafic sequences. Seams are narrow at 10 em to 30 em but of high grade. The platinum occurs 10 m to 40 m below the norite/pyroxenite contact.A 60 m wide zone of Light Sulfide Mineralization (LSM) of less than 1070 sulfides extends from the lower gabbronorites into the upper pyroxenites. In this LSM, four enriched zones carry up to 5% sulfides. The most widespread is termed the Main Sulfide Zone (MSZ), below which is No. 2, No.3 and No.4 Sulfide Zones. The MSZ carrying pyrite, pyrrhotite and chalcopyrite is a multielement ore with components of PGE (pt-Pd-Rh), nickel, copper and cobalt, and gold and silver.Extensive exploration programs have been carried out and the intention is to begin large-scale mining. However, with Russia supplying metals to the western markets, South Africa's cutback on production, and an end to the Cold War, delays have arisen."

Jan 1, 1994

By N. Hwang

There has been increasing interest in the use of robotic machines, and several prototype robotic machines have been developed to automate the grit-blasting process for the purpose of steel bridge maintenance. To utilize such a robotic grit-blast machine effectively, the first consideration is automating the determination of the rust surface area to blast, on the basis of standards of practice, in a rapid manner. This study aims to propose a method to rapidly and accurately determine the rust surface area on steel bridges to blast, with consideration for the standards of practice, from images acquired via a blasting machine. The first step is to perform a color space conversion to transform the input image from a red/green/blue (RGB) color space to a hue/saturation/intensity (HSI) color space. The next step is to detect the presence of rust, using pixel-level classification via the C4.5 decision tree algorithm. Then it is necessary to confirm the blasting area by verifying whether the rust detection result satisfies the specified criteria on the basis of standards of practice. The proposed method was validated on 39 test images with various characteristics with respect to the degree of rusting and rust distribution type. The experimental results showed that the average accuracy rate of rust area classification was about 97.63%, and the success rate of the final decision of blasting area determination was 100.00% for 39 test examples. The whole processing time took an average of only 0.86 seconds per image. The preliminary results demonstrated that the proposed method not only determined whether rust was present in an image and the amount of rust but also indicated whether blasting was necessary, and, if necessary, it rapidly specified the rust surface area that should be blasted on the basis of standards of practice. The proposed method could be successfully incorporated into a robotic grit-blast machine.

Aug 1, 2013

By Gary Walters, Thomas Gonzales, David George, William Davenport, Andreas Siegmund, Suping Yao, Shijie Wang

The previous survey of world copper smelters was in 2016 (Copper, 2016). The copper smelting industry has grown and improved considerably since then, including continuing growth in China and modernization in Japan (Extraction, 2018). Outotec flash smelting and Outotec flash smelting/Kennecott - Outotec flash converting continue to be adopted while newer processes continue to be adopted in China. In addition, some of the world's original flash furnaces have been completely rebuilt (Extraction, 2018). This paper provides recent industrial production data and discusses these new developments. INTRODUCTION A world copper survey was redone in 2016 after a thirteen year lag since 2003. Some of the notable changes were the significant increases in production particularly from China. Since then, several smelters have gone through modernization processes and decommissioning of older technologies. This paper will review the notable changes since the last publication at Cu2016. In the last paper, Copper Smelting: 2016 World Copper Smelter Data, the author gave an audible sigh after observing that copper smelter sites as well as new and notable smelters have been spreading like wildfire in China since 2003. Indeed, seeing is believing. Figure 1 shows the Ningde Copper Smelter (double flashing, 400,000 MT Cu/Year capacity) that started up producing copper in 2018; Figure 2 shows the Nanguo Copper Smelter that is under construction with 300,000 MT Cu/Year capacity (first phase, side blown smelting and continuous top blown converting). We should not only admire the Chinese copper industry’s significant technological developments, but also the copper price support that it has provided throughout this century.

Jan 1, 2019

By S. Hussien, P. Somasundaran, P. Patra

"Rare earth elements (REEs) are essential for many applications in electronics, energy harvesting, and defense. The common resources for economic extraction of REEs are oxides such as bastnaesite and monazite, which are scarcely available in the earth’s crust. On the other hand, REEs are available in many clay and phosphate ores where REEs substitute Ca or Si in the mineral lattices or as physically adsorbed cations at negatively charged sites on the clay surface. While REE oxides readily dissolve in acid, making the chemical leaching of REEs an economically viable option, adopting a similar approach for leaching of silicates and phosphate ores is unfeasible because of significantly low REEs content in these ore deposits. Bio-leaching approaches are environmentally benign and economically viable. We investigated the bio-leaching (Acidothiobacillus ferrooxidans (Af) and the fungal Aspergillus niger (An)) of REEs from a phosphate ore, and examined the factors governing the leaching processes. Based on the shake flask leaching studies, an increase in surface area combined with an increase in pulp density (1-15 wt. %) was found to lead to an increase in the amount of REEs leached. In contrast, an increase in the surface area by reducing the particle size from 75 to 35 led to a decrease in the amount of REEs leached. These differing attributes are proposed to be due to the poor bacterial growth/activity with high F- ions in the leaching media, F- released from the edge-sites of the smaller particles. On the other hand, several advantages that associate with the Af bacterial bio-leaching processes relate to the media composition (Mg2+ and (NH4)+) and phenomena occurring at the electrical double layers of the mineral and bacterial- water interfaces. These studies suggested that leaching of particles occur in a layer-by-layer manner.INTRODUCTIONRare Earth Elements (REEs) are essential for many important applications, such as in electronics, energy generation, and defense. The common resources for economic extraction of REEs are typically carbonates such as bastnaesite and monazite, which are scarcely available in the earth’s crust (Y. Kanazawa and M. Kamitani, 2006). REEs are abundantly available in many clay and phosphate ores where REEs substitute Ca or Si of the mineral lattices. Conventional acid leaching of REEs from oxides is not economically feasible for clay and phosphate ores because of significantly low REE content (parts per billion) in these ores (Tian, J., Chi, R., Yin, J., 2010a; Moldoveanu G. A. and Papangelakis V. G., 2013; WK Goyne, LS Brantley and J Chorover, 2010). In some cases, REEs could be extracted from these ores via chemical leaching routes as they constitute reasonable amounts of REEs (0.1 - 1% REEs). A major challenge faced in general in chemical leaching processes (Chi, R., 1988) is the loss of REEs in the phosphate/gypsum precipitates/crystals, which are overcome in a step-by-step manner by sequentially removing impurities such as fluorine and calcium, including steps carried out at elevated temperatures. On the other hand, bio-leaching approaches provide environmentally benign and economical alternatives. Acidophilic bacteria are currently being used for industrial scale bio-leaching of Au/Cu/Ni from low grade ores. Studies on bioleaching of REEs from red mud (Al2O3) using Penicillium tricolor and Aspergilus niger (An), and, of bio-leaching (lab-scale) of phosphate rocks using Acidithiobacillus ferrooxidans (Af) have been reported (Boon, M., Heijnen, J.J., 1993; Qu, Y. and Lian, B., 2013). We conducted bacterial (Af) bio-leaching of REEs from a phosphate ore in shake flasks and columns, while examining the key factors that govern leaching kinetics."

Jan 1, 2016

By H. E. (Buzz) Neal

"Abstract - The Labrador Trough contains world-class iron deposits which have been mined since 1954. The direct shipping of Knob Lake ores were mined at Schefferville from 1954 to 1982. Concentrate production began in 1961 in the southwest end of the Trough, with three mines currently producing concentrate and pellets at a rate of 35 Mt per year. West and north of Schefferville, several billion tonnes of taconite have been outlined in fine-grained, cherty magnetite iron formation. Several deposits of highly metamorphosed magnetite-specularite iron formation are located west of Ungava Bay. Numerous studies have shown that this medium- to fine-grained iron formation can be beneficated to 66% to 68% iron. In the area from Wabush Lake to Mont-Wright, a medium- to coarse-grained friable specularite-quartz iron formation is repeated by folding to form several large deposits. In this area, three mining operations are located with reserves and resources in the order of 5 billion tonnes.The iron deposits occur within iron formation in sediments in the extensive Proterozoic geosyncline called the Labrador Trough. Several facies of iron formation within the Sokoman Formation reflect variations in chemical composition and depositional conditions. The correlation between the mineralogy and textures is discussed to illustrate the development of different types of iron ores. This band extends for about 1100 km southeast of Ungava Bay through both Quebec and Labrador. Further south, it turns southwest past the Wabush and Mont-Wright areas to within 300 km of the St. Lawrence River. The iron formation is essentially folded and faulted along most of its length. The degree of metamorphism is variable, ranging from intense in the northern and southern portions to greenschist facies in the central portion.The stratigraphy, structure and mineralogy of the producing mines are described along with the history of discoveries. Geological input is required to achieve the strict specifications of the international iron ore market."

Jan 1, 2000

By A. R. Laplante

"In this paper, the performance of the Knelson Concentrator and of the batch and continuous Falcon Concentrators are compared. The units are based on different operating principles, and as such they perform quite differently. The Knelson yields very high free gold recoveries over a wide size range of both the recovered and rejected species. It is ineffective in recovering very fine ( <15 µm) or flaky gold, as encountered in flotation feeds, concentrates or tails. It is the: preferred unit for gold recovery from grinding circuits. The batch Falcon is effective in the fine range, typically less than 37 µm for gold. Its recovery zone is quickly saturated when there is significant heavies in the feed. It works best as a pre-concentration unit. The continuous Falcon is a versatile unit which is capable of recovering fine heavies (density down to 5 g/cm3 ), especially from coarser gangue. INTRODUCTIONThe purpose of this presentation is to describe the mode of operation of two Canadian centrifugal concentrators, the Knelson and Falcon. It is hoped that it will prove informative to prospective users in the selection, testing and optimization for applications of either machine. The work is based on testwork both in Canadian mills and at McGill. I am indebted to many colleagues at these locations. Appropriate references will be made to articles further describing the work, either already in the open literature or in preparation.Although this work is meant to be more practical than scholarly, it is appropriate to begin by considering how the two units achieve selective recovery. This will become useful in establishing a suitable testing methodology, which will then be described, and interpreting typical results. In the last section I will attempt to define appropriate applications for the two units. This is a thankless task, as I am likely to miss some applications or to make projections based on partial results, as much of the work is still in progress. In deference to the reader and both manufacturers, areas where reasonable doubt still remains will be identified."

Jan 1, 1993

By Morris Wong

"An antimony-bearing gold ore was studied in a cyanide slurry containing 7 -20 ppm dissolved oxygen. 1 g/L NaCN at pH 9.5 and 48 hours retention time is required to extract 94 % of the gold from the 90 % minus 200 mesh ore by conventional cyanidation at a 7 ppm O2. As oxygen concentration was increased to 20 ppm, the conditions required to extract the same amount of gold were: 0.25 g/L NaCN, 16 hours retention time and 80% minus 200 mesh. Compared to conventional cyanidation, oxygen-enriched leaching was shown to reduce retention time by three times and cyanide consumption by four times. The kinetics of gold dissolution related to the dissolved oxygen concentration in slurry was expressed by following equation:XAu = 100 * (Kt + I0) / (1 + Kt + I0)where XAu is the percentage gold extraction; t is the retention time; K and Io are the slope and the intercept of the plot of XAu I (100 -XAu) vs. t respectively. The values of Kand Io depend upon the concentrations of cyanide and oxygen, the fineness of grind and the origin of ore sample etc.. A preliminary cost analysis was also performed to justify the use of oxygenating slurries.IntroductionGeneral:It was proposed almost 149 years ago (Elsner 1846) that oxygen is required for the dissolution of gold in cyanide solution. However, little attention were paid to oxygen application in the gold milling industry during the following one hundred years. Due to the constraints of gold price, reagent costs, refractory ores, and environmental issues in the past decade, the oxygen enhancement in the cyanidation process was introduced to the gold milling industry for increasing operation efficiency, reducing production costs, and meeting the requirement of environmental standard.The advantages of oxygen-enriched cyanidation have been reviewed by several investigators (Hague 1992, Jara et al 1992, Henderson 1989, Loroesch et al 1988, Elmore 1987, Cathro 1963). Common to all conclusions are the following advantages."

Jan 1, 1995

By E. W. Garner

THE greatest problem confronting business managers in modern times is not production, but distribution. It would be easy to expand productive output, but it is difficult to find markets for all that is produced. The fundamental source of economic difficulty, in the view of many observers, is a lack of proper balance between productive capacity and consumptive capacity. The studies conducted by the Brookings Institution on the general subject, "The Distribution of Income in Relation to Economic Progress", have led to conclusions of far-reaching significance, which may be summarized briefly as follows: (1) We have never lived beyond our economic means or capacity. (2) We have not been suffering from general overproduction. (3) We have not as yet reached a stage in our economic evolution at which it is possible to provide adequate standards of living for everybody. ( 4) It would require less than a 25 per cent increase in purchasing power among the masses to absorb our full productive capacity. (5) Production-curtailment programmes-whatever their merit in meeting temporary maladjustments-can only lead to national impoverishment. (6) Our inability to find markets adequate to absorb the full output of our productive establishments is explained by the unequal distribution of income and consequent restricted flow of purchasing power through consumptive channels. (7) The slow rate of growth of consumptive demand serves to retard the rate at which new capital is constructed, and hence the rate of economic progress. (8) The primary need is a rapidly expanding total income, and a broader diffusion of this income among the masses of the people. (9) A broader diffusion of income can best be achieved by reducing prices as rapidly as increasing efficiency will permit. That is to say, the benefits of technological progress, mass production, and low unit costs must be promptly passed on to consumers in the form of lower prices-giving more for each dollar.

Jan 1, 1936