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By J. Guha, R. Kanwar, G. Archambault, A. Tremblay

The Copper Rand Cu-Au deposit lies within a shear zone which strikes N50-60W and dips steeply southward (50°-55°) and extends over 1. 5 km with a thickness which varies form 350 to 425 metres. Mineralization, inside the shear zone, is structurally controlled by a dilation mechanism which can be explained by a fracture dilatancy model. The principle of this model involves the mechanics of overriding of irregular planes and surfaces of faults and schistosities, These structures are characteristic features of the Copper Rand shear zone. A structural analysis of the shear zone has been carried out to establish relations between the different structures within the shear zone and their evolution with the development of the shear zone. A geomechanical interpretation of the Copper Rand shear zone explains the formation of internal structures such as faults, schistosities and microstructure during the shearing. This interpretation confirms Ramsay's theoretical model on the geomechanical evolutuion of shear zone development, and the experimental work of Morgenstern-Tchalenko on the simulation of shear zones in clay models. The geomechanical interpretation of the shear zone demonstrates that at the onset, subsidiary fracture patterns are developed in second order faults in the following sequence. At peak strength Riedel shears ( R and R') are formed which propagate outside the strength, restraint (P) shears are developed in the thrust attitude within the shear zones. Principal displacement shears (D) develop toward residual strength in the direction of movement. Shear lenses are formed by the interaction of these shear discontinuities and these facilitate the formation of schis tosi ties with the continuation of the shear displacement within the main shear zone. While the main shear zone and the P and D shears within the main shear zone were in continual movement, the Rand R' structures, once formed, retained a simple fracture pattern and moved little outside the shear limits in comparison to the main shear zone. Parts of these structures inside the shear zone were reactivated by subsequent movements and deformed into folds to account for the present attitudes of the HW-1 and HW-2 and HW-3 structures. This geomechanical model for the shear zone with its subsidiary structures (R, R', P and D shears) is also applied on a larger scale to the Dore Lake shear belt and explains the different structures accompanying it. The initial development of the WNW shears (most are ore deposits) was followed by the subsidiary structures of the Dore Lake shear in a north-south stress field and is well defined by the movements characteristic of the different structures. It is concluded that the Dore Lake shear cannot be the prolongation of the McKenzie Narrows shear but it seems that this prolongation relates to the Henderson-Portage shear zone.

Jan 1, 1984

By SeyedBijan Mahbaz

Development of Geomechanical Earth Models (GEM) is a prerequisite to reservoir management, involving issues such as stress path analysis, prediction of induced seismicity and sanding initiation, and coupled flow-stress modeling that leads to more realistic predictions of oil rates and rock response. Part of GEM development is the stipulation of the 3-D lithostratigraphic disposition (geometry) which is used to choose the geomechanical units. The digital geological model is then populated with quantitative and semi-quantitative data on rock properties, fluid properties, saturations, initial conditions (p, T, [_]) and other information. Both fluid and solid properties are needed this requires integration of geomechanics skills with geophysical and rock physics skills, and this article deals with a subset of this integration process, with an example from two wells in southwest Iran.Rock physics approaches are used to predict reservoir rock and fluid properties with wellbore and 3-D seismic data, which are also used to interpolate rock mechanics properties to the inter-well regions. The first step in a generic rock physics approach is diagnostic and involves the introduction of a suitable Rock Physics model.Acoustic impedance (AI), shear impedance (SI), and density (_) are the fundamental rock properties usually derived using AVO equations, and these parameters, along with attenuation coefficients, can then be correlated to static rock mechanics properties that define deformability and perhaps even strength. In this study, Poisson Impedance is introduced as a new seismic attribute used for lithology and fluid differentiation in the FahliyanFormation (reservoir rock) in two oil wells in the southwest of Iran. To do this, a novel rock physics model was developed for this naturally fractured carbonate reservoir.Currently, these data are also being used to correlate to a limited rock mechanics data base to develop a more extensive GEM to serve as input to more general geomechanical and reservoir modeling tasks.

Jun 1, 2012

By B. Vorobyov

A Canadian company, Sight Power Inc., has developed a revolutionary, fully automated shaft monitoring and inspection system for deep-level mining based on a 3D mobile laser scanning technology. It consists of a special hardware unit and proprietary software with Artificial Intelligence elements for object recognition, features identification and change detection. The main purpose of this system is to significantly improve the safety of underground mining as well as to increase the available hoisting time thus generating substantial additional revenue for the mine.

Aug 1, 2013

By R. Grau

"After commissioning and start-up of the first 500m3 TankCell® flotation cell in 2014, the over 300m3 mechanical flotation cells have earned their place in large-scale flotation operations. These 500 to 630m3 cells, designed for projects with large throughputs, are proven to provide savings in project capital and operational expenditure through savings in foot print, energy consumption, and less equipment to install and maintain. Addition to savings in different phases of a project, these cells provides operational flexibility and has shown improvements in metallurgical performance. In this paper a case study from Kevitsa TankCell® e500 installation and Buenavista del Cobre TankCell® e630 installations will be given.INTRODUCTION After development (Grönstrand and Bourke, 2008), characterization (Morales et al. 2009; Yanez et al. 2009; Grönstrand at al. 2009), validation (Elgueta et al. 2009; Coleman and Dixon, 2010), and more than 350 industrial installations of the Outotec TankCell® e300 flotation cell, the well proven energy efficient TankCell® product family introduced the TankCell® e500 forced-air flotation cell late June 2012 (Outotec.com, 2012). The introduction of the 500 m3 flotation cell followed by introduction of a 630 m3 flotation cell, TankCell® e630, in October 2014 (Outotec.com, 2014). These large flotation cells are designed for projects with high throughputs where the number of cells needed for operation with smaller equipment would become large. The benefits of this size of flotation cells comes from the lower capital expenditures due to lower equipment costs, savings in plant footprint, less installation work with less auxiliary equipment, lower energy consumption, and less units per installation resulting in less components, spare parts and maintenance.The first TankCell® e500 was commissioned and taken into operation in October 2014 at FQML Kevitsa Cu-Ni-PGE concentrator, nowadays owned by New Boliden. The first TankCell e630 was taken into operation in January 2018 at GrupoMexico’s Buenavista del Cobre Cu-Mo concentrator. The start-ups of the first TankCell® e500 and TankCell® e630 followed with test work where the hydrodynamic performances of the cells were characterized and metallurgical performance studied. The results of the TankCell® e500 test work were presented in detail by Mattsson et al (2015a; 2015b) and TankCell® e630 by Grau et al. 2018. In this paper the metallurgical improvements achieved with the large cell installations will be presented."

Jan 1, 2019

By BARRY BANNATYNE

Gypsum in Manitoba is quarried from the Jurassic Amaranth Formation a1 Gypsumville and Harcus; it has been mined near Amaranth and Silver Plains. At Gypsumville, gypsum is carbonate- free but has thin clay laminae between gypsum layers; the rock is folded in places, and some anhydrite is present. At Harcus, gypsum contains scattered dolomite, both as patches in a penemosaic pattern and as thin layers; small chalcedonic concretions also can be found. The quarry at Harcus was opened late in 1978 and currently produces about 100,000 tonnes annually. The two inactive mines near Amaranth operated from 1932 lo 1963 and from 1967 to 1970, and contain a central anhydrite layer. The mine near Silver Plains was flooded from an underlying artesian aquifer in 1975 and has not been reopened. Manitoba gypsum is used in cemem plants in Mani1oba and Saskatchewan and in wallboard plants in the three Prairie Provinces.

Jan 1, 1984

By J. Olsson

The paper describes and discusses the use of stainless steels for leaching plants emphasising the duplex family, i.e., austenitic-ferritic stainless steels. This group has generally twice the proof strength of the more common 300-series austenitic grades, which implies possibilities to reduce the gauge at construction of pressure vessels and atmospheric tanks and vessels and thereby possibilities to reduce the weight. The duplex grades have also higher surface hardness resulting in better resistance to mechanical wear, i.e., abrasion and erosion corrosion. The lower contents of nickel and molybdenum imply lower cost and a more stable price considering the present market situation for these alloying elements. Corrosion data from laboratory and pilot plant tests, as well as examples of applications of duplex and highly alloyed austenitic grades, are presented. Cu2007 - Volume IV (Book 1) The John E. Dutrizac International Symposium on Copper Hydrometallurgy Edited by P.A. Riveros, D.G. Dixon, D.B. Dreisinger, M.J. Collins Toronto, Canada,

Jan 1, 2007

By John R. Morgan, Peter Graham

"Onakawana Development Ltd. and Mana/ta Coal Ltd. have completed feasibility studies on a large lignite deposit located in the James Bay lowlands of northeastern Ontario. The mining plan described in this paper would supply coal for approximately a 33-year period with peak production in the early years of approximately 6.5 million tonnes per year then declining to 1.2 million tonnes in year 33. This paper describes the geology, resources, lignite quality, mine planning and related topics. LocationThe Onakawana lignite deposit is located in northeastern Ontario in the James Bay lowlands (Fig. l). The Ontario Northland Railway crosses the property and links it to Moosonee, JOO km further north, and Cochrane 180 km south. The area is crossed by latitude 50° 37', the approximate latitude of Calgary. Toronto lies 800 km south of the study area. History of Development The deposit has been known since the late 1600s when early English settlers extracted limited amounts of lignite for use at Moose Factory. The deposit has undergone sporadic periods of exploration activity in the late 1920s and early 1930s when the Ontario government drilled 116 holes, sunk two exploration shafts and published several technical and economic studies. Interest in the property was reactivated from 1939 to 1945 when the Timiskaming and Northern Ontario Railway Ltd. drilled 182 additional closely spaced holes, excavated a test pit adjacent to the rail line and installed a boiler for testing purposes. In 1965, Alberta Coal Ltd., the predecessor of Manalta Coal Ltd., first became involved. Since then a further 182 holes have been drilled and coied, and the existing test pit reopened for sampling. In 1980, various reassessment studies were launched, including geology, mine engineering, conceptual design and environmental assessment studies. The following discussions have been drawn extensively from these reports."

Jan 1, 1985

By J. A. Reid

THE views and observations expressed herein on this old but constantly recurring question are our own, no effort having been made to align them with standard texts. Therefore, while they may find general acceptance amongst fellow engineers, they must stand as personal opinions and as such are open to debate and discussion. In order properly to consider the subject, it should first be 'set in proper perspective. Why are Prospects Examined? Prospects are examined to determine whether they may contain economic concentrations of metals or minerals, the legitimate mining business being run, pretty largely, to make money. Next to food and clothing, modern civilization is based on metals, with which are included in this discussion minerals, oils, and fuels. A constant and increasing demand for the common metals requires the location of replacements for depleted orebodies, while the use and appreciation of new metals brings increasing demand for them. Aluminium is a good example of a metal which has, within recent years, made great progress. Today, we are becoming increasingly aware of magnesium, chromium, tungsten, thallium, and other lesser known, metals.

Jan 1, 1945

By Roderick C. McDonald

Great Bear lake, the fourth largest body of water on this continent, comprises an area of approximately 12,000 square miles, and is set astride the Arctic circle, with a large portion of it witnessing both the Arctic winter night, and the Arctic summer day with its midnight sun. The very name itself, Great Bear, suggests an Arctic region. The seasonal contrasts at Great Bear lake are very marked by the cold and darkness of winter, and the warmth and brightness of summer. Signs of winter such as low clouds, snow, sleet, fog, and night frosts, generally appear the latter part of August, while ice forming on bays during the last two weeks in September ends boat travel on the lake about September 30th.Early in June the ice leaves the river mouths, during the last ten days of the month it disappears from small bays, and at some time during the last two weeks of July the main body of the lake becomes navigable. In 1916, the ice disappeared earlier than usual, and the lake was navigable on July 5th. Great Bear river generally breaks up about June 1st, but, on account of ice cliffs and floes, it is not navigable with safety until early in July. Even then, the traveller is confronted with the Charles rapids, but these might be overcome by a wagon or motor road, such as the one from Fitzgerald to Fort Smith: However, in 1931, Mr. A. W. Boland, Fort Norman, N.W.T., carried with scow and motorboat practically all freight between Fort Norman and LaBine point and Hunter bay, at the east end of the lake. During July and August, two types of clothing are required, for, although the days are mainly ones of warm sunshine, the nights are cloudy and cold. In the winter season, fur clothing is used exclusively. Considerable timber, mainly white spruce, suitable for fuel and building purposes, borders the lake and extends eastward to the Coppermine river. North of the lake, no timber is found except in the river valleys, but with oil and coal possibilities near Fort Norman, the fuel situation might be solved.

Jan 1, 1932

By Mike Smith, George Chung

"A 23 million dollar Flotation Plant has been commissioned at the Iron Ore Company of Canada in 1998. Nine OK-50 cells &re used to float silica in this 1,400 tomes per hour plant. The paper details project development, construction and operating results. This plant gives IOC the capability to produce not only high quality blast furnace pellets of varying silica, CaO and MgO levels, but also a high iron, DR grade pellet. The first activity was simply to sit down with the suppliers, Outokumpu, Wemco. GL&V and Svedala, to discuss applications and share experiences. We learnt what each supplier had to offer, what features would particularly suit this application, what options were offered, what were the materials of construction, how the equipment is maintained, which wear parts require replacement, etc., etc. We tried to learn as much about the equipment as the suppliers themselves knew. Then we tried to learn more: we contacted users and asked about any weak points, which options were worth incorporating and which items were not. We then discussed these points with the suppliers and established how potential problems might be overcome."

Jan 1, 1999

"Since World War II, urban communities have expanded at an unprecedented rate. The industrial mineral industry supplies the sand, grave], limestone, crushed rock, cement, gyp-sum, etc. for urbanization. Most de-posits in use are close to or within communities. Pollution of water and air has become a matter of public concern. Waste disposal and the effects of noise and vibration are subjects of public debate. Need for the reclamation of land after operations such as strip mining is discussed in magazine articles and on TV pro-grams; i.e., the general public is educated in the unattractive features of mining.Legislation is on the books and being drafted to regulate mining operations and their side effects. To avoid over-regulation and restrictive legislation, it is necessary that the public be educated and legislators informed of problems peculiar to the mining industry. Our side of the story needs publicity."

Jan 1, 1968

By J. Fellowes, Z. Liang, J. Robson, M. Kenyon

"Dispersoids play a significant role in the recrystallization and texture development for wrought Al-Mg-Si (6xxx series) alloys by inhibiting grain boundary motion. It is therefore important to understand the precipitation kinetics of such particles. It is the additions of Mn and Cr in Al-Mg-Si based systems that can lead to dispersoid phases being formed. These phases are currently thought to nucleate on ß’-Mg2Si via an intermediate semi-coherent precipitate. Scanning transmission electron microscopy (STEM) has been conducted to study the precipitation of a-Al(CrFe)Si and a’-AlCrSi dispersoids. Corresponding electron dispersive spectroscopy (EDS) has been used to distinguish the dispersoids. The volume fraction and size distribution of dispersoids has been measured as a function of distance across a grain. Electron probe microanalysis (EPMA) has been conducted to study the inhomogeneity of elements in the cast structure and the effect on dispersoid precipitation. Dispersoid free regions have been observed in the microstructure correlating to regions depleted in the dispersoid forming elements.INTRODUCTION Al-Mg-Si (6xxx series) based alloys are increasingly being used in the automotive industry. The primary reason is to reduce the weight of vehicles, resulting in a reduction of CO2 emissions and increased fuel efficiency. The demand for 6xxx series is predicted to increase over the coming decade. Due to the high cost and CO2 emissions produced by raw extraction of aluminium, close loop recycling of these alloys becomes a more important process. However recycling of automotive alloys can be difficult due to pick up of impurity elements such as Mn, Cr and Fe. The addition of these elements can form dispersoid particles during early heat treatment processes. Although a controlled population of dispersoids is necessary to control the grain structure during thermo-mechanical processing, a significant change to the dispersoid population due to a composition change could profoundly influence the final microstructure, affecting the final properties of the material. More research is required on the precipitation and effect of additional minor alloying elements; in order to increase the 6xxx series alloys recyclability."

Jan 1, 2018

By C. I. Walker

Field tests at a number of large mineral processing operations have been undertaken to better understand the wear life impact of different aspects of pump design, materials of construction and maintenance procedures. Data are presented for wear rates, and typical result variability is explored. To improve the availability of pumping equipment in a milling circuit it is not only important to improve the wear life, but also reduce the variability in the wear life of components so that the incidence of premature failure is lessened. Localised gouging wear due to flow separation and turbulent eddy formation is often the point at which part-holing occurs. A number of improvements to the design of pump impeller and throatbush (suction side liners) to reduce the localised gouging wear are outlined. Also, results are presented on the use of composite materials (mix of metal, rubber and ceramic) for throatbush materials to protect specific areas against wear.

Jan 1, 2012

By Rodney A. Cooper

The Mary River iron ore deposits were discovered in the 1960?s. The high quality of the deposits was immediately evident, and drilling programs were successful in defining a resource adequate for supporting a feasibility study. Through a combination of ownership, market and political forces, the deposits were not developed. Having missed the window of opportunity, the project remained dormant for over three decades. Baffinland Iron Mines Corporation, with its 100% ownership of the Mary River deposits, began trading publicly in 2004. Modern exploration and metallurgical test work began in 2004 and has continued in 2005 and 2006, resulting in total expenditures during this period of almost C$60 million. In May 2006, an engineering team lead by Aker Kvaerner E&C, a division of Aker Kvaerner Canada Inc., completed a scoping study based on the first of five identified deposits. Highlights of that study include direct shipping of high quality lump ore to Europe over a 34 year mine life at a production rate of 10 million tonnes per annum, based on an indicated resource of 309 million tonnes at 66.1% Fe and an inferred resource of 28 million tonnes at 65.9% Fe. Capital costs were estimated at C$1.5 billion. Using iron ore prices approximately 36% below that of the 2006 market, a pre-tax internal rate of return of 15% was estimated assuming equity financing. Payback on initial capital was 5.9 years. The pre-tax life-of-mine cash flow was estimated to be C$6.3 billion. As a result of this study, Baffinland initiated a Definitive Feasibility Study, under the management of Aker Kvaerner, which is scheduled for completion in December 2007. This paper touches on the geology of the deposits, the current resource and the outlook for expansion. Project permitting, construction planning, logistical challenges and ocean shipping considerations are discussed, providing a current perspective on the project scale, scope and timeline for commercial production. In addition, an overview of the Company?s bulk sampling program will be provided.

May 1, 2007

By E. S. Moore

To properly understand industrial conditions in Spain it is necessary to consider the early history of the country. Spain is very backward in many lines. They use the sickle for cutting grain, and plows for cultivating the land, which resemble those of Biblical days. In the great mining camp at Bilbao only one steam-shovel is in use, although about two hundred million tons of ore has been produced, and this almost entirely from open cuts. It is the lack of industrial development, such as is found in many other countries, which permits large mining enterprises to be controlled almost entirely by foreign capital, although Spain is such an old country, and which permits mines opened in the days of the Phoenicians to still operate. Such deposits in America would be exhausted in a comparatively few years. The Phoenicians are supposed to have reached Spain about 1100 B.C. and to have worked some of the properties in the Rio Tinto district. The Carthagenians invaded the country about 236 B.C., and they were driven out about 205 B.C. by the Romans. The Romans ruled until 483 A.D., when they were overthrown by the Visigoths. Then, about 711 A.D., the Moors from Africa became prominent and they were finally expelled by the Spaniards in 1492. Spanish power reached its zenith under Phillip II, during the latter half of the 16th century, and since the close of that century the country has lost its prominent place among the nations. There are some evidences of revival in the development of good roads, the construction of a satisfactory network of railways, and the building of magnificent thoroughfares through the capital city, Madrid.

Jan 1, 1927

By M. Tsesarsky, M. Hazan, E. Gal

"Rock masses comprised of stiff inclusions in softer matrix are common in various geological environments. The heterogeneity and multi-scale nature of these materials make the evaluation of their mechanical properties a challenging task, which cannot be accomplished using conventional laboratory tests and composite mixture rules. We employ the homogenization method to estimate the mechanical properties of geological materials with inclusions. The homogenization method solves the equations of elasticity on the material (microscopic) scale for a unit cell subjected to unit strains under periodic boundary condition. The micro-scale elasticity equations are solved using the Finite Elements Method, and are in turn used to obtain the structure scale (macroscopic) material matrix.In this research, Finite Element models for unit cells with spherical and ellipsoidal inclusions were developed. Using the unit cells, a parametric study of the geometrical and statistical microscopic properties of the material composites was performed. The following parameters were studied: volumetric ratio, Young’s modulus ratio, size-distribution of inclusion and inclination angle of inclusions. The main purpose of the parametric study was to study the deviation from isotropy as a function of the aforementioned parameters.It was found that for volumetric ratio of 5%-40%, the deviation from isotropy increases, as the volumetric ratio of inclusions increases. For spherical inclusions, most of the cases studied exhibit quasiisotropic behaviour; whereas ellipsoidal inclusions exhibit considerable deviation from isotropy. The inclination of the ellipsoidal inclusions enlarges the deviation from isotropy (9% at random orientation and 26% at 0°)."

Jan 1, 2015

By T. Scully

Since early days in coal mining, it has been known that some coals and the carbonaceous materials associated with them will heat and fire spontaneously. Many theories have been advanced to account for this phenomenon, but it is only within comparatively recent years that any scientific research has been carried out to determine the causes of this heating, the conditions which bring about its occurrence, and the reason why different coals heat with a varying degree of readiness. So far, this research has not cleared up these points entirely, but a great advance has been made in our knowledge of the matter. In general, any coal will fire spontaneously, although with a varying degree of readiness, provided conditions for its doing so are favourable enough. These conditions are that the coal must be in a fine state of division, that sufficient oxygen must be present for rapid oxidation, and that the air current passing must be so small that it is insufficient to carry off the heat produced by this oxidation. Many other minor factors, however, contribute to bring about spontaneous heating, either by producing initial heat themselves or by inducing the other major conditions.

Jan 1, 1931

By O. E. Humeniuk, A. I. A. Salama, M. W. Mikhail

"The Western Research Centre (WRC) of CANMET operate a unique pilot plant facility where ongoing R&D on coal preparation and mineral processing is conducted. The pilot plant carries out two functions: coal preparation processing using state-of-the art technology and coal-liquid mixture preparation with intensive cleaning circuits that can also be used for mineral processing. In total, the pilot plant includes more than 30 different flowsheet options. The facility is dedicated to small and fine coal, and designed to be flexible and versatile.This paper describes the use of a pilot-scale facility as a research tool for process control development, fine coal beneficiation, development of coal-liquid fuels technologies, development of process models and testing and evaluation of new developments. The pilot plant is used to assist in resource development by evaluating and optimizing flowsheet selection, and producing sufficient samples for utilization tests. The facility is also an important tool for evaluating and testing samples from troublesome circuits of operating plants to find means to optimize and improve recovery, particularly of fines circuits.Detailed examples are given to demonstrate the role of a pilot scale facility in coal preparation R&D, coal industry development and optimization of coal processing operations. These examples include the development of heavy-medium cyclone computer control system, detailed evaluation of beneficiation of a coal deposit with high clay content, development of column flotation, and its role in fine cleaning circuits and treatment of ultra-fines in relation to intensive cleaning, the importance of testing coals in different processes, and cleaning processes influence on coking quality and other utilization applications. The potential of the facility for helping the mineral industry is also described."

Jan 1, 1992

By Stanley G. Butcher

"The methods generally applied to predict performance and financially evaluate beneficiation options are reviewed.Typical costs f or a western Canadian thermal coal operation are examined. Preparation-from truck dump to loadout-frequently amounts 10 over a quarter of total minesite costs. Failure to achieve projected yield-whether caused by mine or plant problems-s-substantially increases production costs because more coal has 10 he mined to meet a specific market demand. Problem identification by mass/ash balances is recommended.Thorough characterization of the coal and associated waste materials and more reliable prediction of beneficiation process performance are therefore essential to determine a project 's financial viability.IntroductionWestern Canadian coal prep a ration plant capacity is partway through a massive expansion program . In 198 1 potential product ion was 14 million tonnes, by 1985 it will be 26 million tonnes per year. Only two years ago the industry was concerned whether it could sustain this rate of growth to meet market demands : now with diminished market demand and lower coal prices being offered by our international competitors there are doubts whether t his potential will be fully employed , even by 1990.One direct consequence o f the occurrence of a variety of coals in a stunningly beautiful but complex geo logical setting such as the Rocky Mountains and their Foothills is that each project is unique. Coal is a low value per tonne product. To supply distant markets from geographically isolated deposit s necessitates expensive , dedicated , infrastructure . T o be profitable these operations must achieve eve ry advantage of the economy of scale.Each of the mi ne complexes commissioned in the 1970s experienced severe problems in the area o f co a l preparation . Most bought their way out , paying for major plant modifications by increasing the scale of their total operation . The current market recession may not allow new operations this route to profitability.The objective of this paper is to illustrate the economic impact of coal preparation problems on the profitability o f the total minesite operation and thus provide a sound basis for decision making process."

Jan 1, 1985

By D. F. Sangster

"Eight volcanogenic massive sulphide districts in Canada and Japan, ranging in age from Archean to Miocene, were selected for analysis. The study revealed that: {I) each district has an average diameter of 32 km; (2) the districts contain 4 to 20 deposits each, with an average of /2 deposits; (3) the average total base metal content per district is 4.6 million tonnes, with a coefficient of variation of32%; (4) ranked in order of size, the largest deposit in each district contains, on average, 67% of the total metal and the second largest about 13 %. The remaining deposits range downward in decreasing proportions. Empirical observations such as these may be used f or evaluating the undiscovered potential of new districts as well as contributing to a better understanding of the distribution and genesis of this important class of base metal deposits. Previous WorkThe characteristic geological features o f volcanogenic massive sulphide deposits have been described by numerous authors over the past fifteen years and it is now widely accepted that these deposits comprise a major ""deposit-type."" In addition to these geological parameters, however, it is now becoming apparent that volcanogenic massive sulphide deposits show several distinctive grade-tonnage relationships. For example, Singer et al. (1975) demonstrated a slight negative correlation between copper grade and ore tonnage in their sampling of 146 volcanogenic deposits. In a study of 110 Canadian Precambrian deposits of this type, Boldy (1977) showed that the size of the modal deposit is 0.39 million tons, that of the median deposit is 1.40 million tons and the arithmetic average is 6.85 million tons. Moreover, Boldy's data show that the average grade of combined base metals (Cu + Zn + Pb) for each of the se three deposit-sizes is, respectively, 6.25%, 5.35% and 6.47%. Because the lead content of Canadian Precambrian volcanogeni c deposits is most frequently less than 1%, the total metal grade is effectively Cu + Zn . From Figure 2 in Bold y (1977), it can be seen that 83% of the deposits fall in the range of 0.l to 10 million tons ."

Jan 1, 1980