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By H. Dundar, C. Dzomeku

An extensive testwork was performed around the HPGR plant at GoldFields Ghana Limited Tarkwa Gold Mine. The HPGR was used to prepare the feed for heap leaching. The circuit was configured in such a way that the edge material from the HPGR discharge was recycled for further crushing while the product from the centre reported to the heap leach section. The set-up of the Polysius HPGR provided an opportunity to study the effect of different design and operating variables. This paper will discuss the results from the tests performed to assess the effect of rolls’ speed and applied pressure on the capacity and the grinding efficiency of the HPGR. Applying different pressure values appeared to have an influence on the amount of edge material recycled.

Jan 1, 2012

By A. Sadough vanini A. Kami

In this paper, effects of different ageing treatments on the mechanical properties, microstructure and formability of 7075 aluminum alloy have been studied. Forming limit diagrams of the alloy have been obtained for four ageing conditions including T6, OA1, OA2 and O. For this purpose, combination of uniaxial tensile tests and the Erichsen cupping tests with different sizes and shapes of sheet specimens have been performed after each ageing treatment. The highest formability and the lowest formability have been observed at samples with O and T6 ageing treatments, respectively. Also, investigation of precipitated microstructures showed that the size of precipitation particles has a significant effect on the formability of the alloy. Formability improves with coarsening of precipitation particles.

Oct 1, 2011

By P. R. A. Andrews

"Garnet occurs in schists and gneisses in all provinces of Canada, all mainly in Quebec and Ontario. There is currently a renewed interest in exploration for economic sources of garnet for abrasive applications because of the inherent dangers from exposure to ground silica from sandblasting operations.High-quality garnet is used for lapping and grinding of glass and ceramics; for coated and bonded products such as sandpaper and cloth; and abrasive wheels for grinding and finishing various metals, woods, rubber and plastics. Low-quality garnet is used for cleaning and conditioning aluminum and other soft mewls, particularly by aircraft manufactures. Garnet may be added to grouting cements for oil-well drilling applications, and it has also been used for low- to medium-level radiation shielding. Garnet has been studied extensively by CANMET and its predecessor, Mines Branch, between 1917 and 1990. Twenty-nine studies relating 10 various aspects of beneficiation are presented and a review of the more important studies is presented. The information includes mineralogy, beneficiation methods, product sizes and analyses."

Jan 1, 1995

By Doug Barnstable

"Quinsam Coal Ltd. is assessing the potential of developing a thermal coal deposit near Middle Quinsam Lake on Vancouver Island. The coal reserve outlined is classified as a high-volatile, bituminous ""A” steam coal and is composed off our separate seams of varying quality within the Late Cretaceous Comox Formation.Open-pit mining methods will utilize a walking dragline and a truck / shovel module as the primary stripping tools. Following washing and mechanical drying in a Baum jig preparation plant, the coal will be transported to the proposed dock at Campbell River for shipment via 55, OOO-DWT vessels to world markets. The paper will outline the development and status of the project to date. IntroductionQuinsam Coal Ltd. is a joint venture of Weld wood of Canada Ltd. and Luscar Ltd . The participants propose to develop a thermal coal mine in the Middle Quinsam Lake area, 17 miles inland from Campbell River on Vancouver Island (Fig. I). By acquiring all the assets of Canadian Collieries in 1962, Weldwood also came to own the coal rights of the area proposed for development. Luscar Ltd . ha s been designated as project manager until completion of construction and thereafter will act as operator of the mine.Surface mining methods will be used to produce approximately 1.0 million short tons of coal annually from the Quinsam property. Seven separate mining pit s will be developed along with the supporting minesite facilities, including a proper paration plant. Transportation routing to Campbell River and the establishment of docking facilities will be required. The initial economic life of the mine is 12 years, with the provision to extend this in the future by developing higher-ratio, auger or underground reserves."

Jan 1, 1980

By A. E. Wraith, J. Protheroe Jones, P. J. Mackey

INTRODUCTION When Victoria became queen in 1837, that technical wonder of the 19th century—electricity— had progressed from being an exciting physical curiosity and was now a field of intense scientific investigation, invention and application. Its role in electrochemistry had been brilliantly quantified by Faraday in 1833–1834, and his earlier discoveries in electro-magnetism were to lay the foundations of electricity generation and the electric motor. In this age of electrical experiment, silver electro-plating emerged as a popular decorative art, at first using batteries to provide the deposition current, superseded by dynamos in the early 1840s. The decorative chemical and electroplating of precious metals was largely pioneered in England by the firm of G.R. Elkington and Co., founded in Birmingham by George Richards Elkington (1801–1865) in 1832, and protected by a series of patents which helped the company establish a leading position in the new field of ‘electrometallurgy’. In the same decade, the technique of electrotyping emerged, the first application of electro- forming by electrolytic deposition. Simultaneously invented by Spenser in England and Jakobi in Russia, but generally claimed for Jakobi, electrotyping involved plating a thick copper layer on to an electrically conducting mould wall embossed or incised with a pattern or profile which would consequently be replicated on the copper deposit—essentially a method of casting by electro-deposition with the mould wall as cathode. Woolrich’s invention of the low voltage magneto-dynamo in 1842 eliminated the need for batteries as a continuous source of deposition power, opening up the possibility of making more massive electroplated deposits, and by the mid-point of Victoria’s reign in 1869, the work of Wilde, Wheatstone and Siemens had produced the self-excited electro-dynamo, capable of higher voltages and yet greater deposition power. In this early Victorian period copper was extracted and refined by methods which had developed step-by-step over many decades. Only relatively rich copper ores containing more than, say, 6% Cu were economically useful, and the final copper product was far from pure. Copper production in Britain was located principally in the Swansea area of South Wales, based upon the ‘Welsh process’ of reverberatory batch smelting and refining, using locally mined coal and ore imported from Cornwall and elsewhere. Silver was an important by-product. Much of the output was exported and South Wales remained a principal supplier to the world copper market until the 1890s. It was here at Pembrey, a few miles west of Llanelli, that a new primary copper smelter was stablished in 1849 under the name Mason and Elkington, arguably to supply the Elkington company’s market for electrotype products.

Jan 1, 2019

By W. Marnette

The copper demand is booming. New epicentres with strong dynamic economic growth have arisen in China and other emerging markets. Furthermore, Europe contributes to higher copper demand due to positive economic growth. China and India are therefore expanding their smelter industries, with the backing of a coordinated policy of global raw material sourcing, which includes investments in raw material deposits and state-run measures to support their international trade and competition. Likewise, Europe faces scarcity of copper raw materials. The copper industry in Europe is historically grown and shows excellence in environmental protection and technical leadership. Recycling has always been an important sector. This reiterates the recycling-know-how which exists in the European sector. However, Europe still relies on importing a considerable amount of raw materials from foreign countries. As a result, the global competition for copper and copper raw materials has increased. Tough competition as regards industrial location and costs, the emergence of corporate concentrations and the use of protectionist trading practices by countries like China and India, which distort the markets, now determine the picture. Hence, a copper smelter in Europe is forced to develop tailor-made concepts to safeguard and improve its international competitive position. It is imperative that this is also flanked by improved conditions on the local level and a European raw material policy which takes account of the changed situation on the world market.

Jan 1, 2007

By Trevor Hamm, Nick Holl

"Cameco Corporation is operator of the world's richest uranium project, the Key Lake mine/mill complex, located within the Athabasca region of Northern Saskatchewan. Mineable resources from the Key Lake ore bodies with an average U,08 content of 2.5% will be exhausted by the year 2000 and open pit mining at Key Lake will be phased out at that time. The mill will continue to operate at increased capacity, using high grade ore from the McArthur River project, a new underground mine at a distance of about 80 km from the Key Lake site. The McArthur River ore with an average U308 content of about 15 % will be blended with separately stockpiled low grade materials from Key Lake with a U,08 content of about 0.1 %. The average (blended) mill feed grade will be about 4%, similar to peak concentrations found in Key Lake ore.The Key Lake ore tailings are presently being placed in the mined out Deilmann pit under sub-aerial conditions, using spigots and a highly efficient pit/tailings drainage system. The tailings resulting from the processing of the blended McArthur River ore will be deposited on top of the Key Lake ore tailings under sub-aqueous conditions. This staged approach shows distinct technical and environmental advantages over an alternative, fully sub-aerial in-pit deposition scheme.The first part of this paper presents an overview of site specific geotechnical and hydrogeological features found at Key Lake and details some of the extensive test and modelling work that was required for environmental impact predictions during the development phase of the facility. The second part of this paper deals with tailings modifications, innovative placement technologies and drainage methods that have been (and will be) employed at the Deilmann Tailings Management Facility {TMF) to produce a highly consolidated tailings body under non-buoyancy conditions. The application of this technology at Key Lake is expected to produce a tailings ""plug"" in the Deilmann TMF which will have a permeability similar to or lower than the original in-situ Deilmann ore, resulting in a minimization of contaminant mass loadings to the environment both during operation and after decommissioning."

Jan 1, 1998

By J. C. Botham, T. D. Brown

"Coke is the most costly item in steelmaking via blast furnaces . Recent innovations in cokemaking have been directed toward reducing this cost while simultaneously improving coke quality and expanding the range of coals used in the process. It is also important to meet increasingly stringent environmental legislation.Improvements in coke quality have been achieved by novel blend selection procedures, by charge density control using both selective pulverization and partial briquetting, and by the use of modifying additives.The Canadian Carbonization Research Association provides a focus for Canadian cokemakin g research which has demonstrated these technologies in a series of pilot-scale experiments."

Jan 1, 1980

By R. S. Forgan

The synthesis and study of a systematic series of phenolic oximes have shown that substitution in the 3-position can greatly affect extractive efficacy. Solid state, solution and gas phase analytical techniques, including X-ray crystallography, EPR and IR spectroscopy and collision induced dissociation mass spectrometry have been assessed for their applicability in interpreting the origins of differences in extractant strength. The dominant substituent effect on pH0.5 is the change in ligand pKa, with the more acidic ligands being stronger extractants. The influence of the 3-substituent on the stabilising intracomplex H-bonding of their copper(II) complexes also affects extractant strength. The 3-NO2 substituted ligand shows the lowest pH0.5 value, due to a combination of its low pKa and a stabilising bifurcated H-bond assembly around the copper(II) centre. Appending an aminomethyl group to the 3-position gives a ligand capable of binding a metal and its attendant anion. These metal salt reagents show potential to open up new flowsheets for the processing of high tenor copper feeds.

Jan 1, 2007

By Jean Descarreaux

"The Rexspar uranium deposits are located near Birch Island in central British Columbia. The property lies within the Omineca crystalline belt of the Cordilleran Orogen. Gneiss, schist, tuffaceous and porphyritic trachyte are the main rock types encountered on the property. These rocks are of pre-Late Triassic or probable Mississippian age.Lenticular bodies of mica and pyrite-rich rock are the host of three closely spaced uranium deposits and are found close to a fluorite deposit. The altered trachytic rock as well as the fluorite and uranium deposits are found in the upper part of the trachyte unit. The latest tonnage estimates are 1,441,820 tonnes averaging 23.46% CaF, for the fluorite deposit, 490,966 tonnes of 0.084% U10afor the 'W' deposit, 164,290 tonnes of 0.074% UP8 for the ""B"" deposit and 459,124 tonnes of 0. 071 o/o UP8 for the ""BD"" deposit.A hydrothermal replacement origin was first proposed for the fluorite and uranium deposits. The mineralizing and altering solutions would have been genetically related to a felsic batholith outcropping a few kilometres south of the property. Another hypothesis has been proposed more recently. A volcanic centre has been tentatively identified in the upper part of the trachyte unit, close to the mineral deposits. The fluorite and uranium deposits could possibly be volcanogenic, rather than related to the Cretaceous felsic batholith.IntroductionFluorite and uranium mineralization occur on the property of Consolidated Rexspar Minerals and Chemicals Ltd. in central British Columbia. The exploration and development works executed over the years are summarized in this paper. The deposits and their geological environment are described but the origin of the mineralization has not been definitely established."

Jan 1, 1986

By Susan W. Campbell, Bruce Regensburg

"The CIM Careers Task Force has addressed industry's concern of a perceived shortage of skilled personnel over the coming decade. The industry is faced with a fundamental shift by young Canadians away from scientific and engineering careers, coupled with the fact that today 's students know little about the minerals industry and have a poor image of it.The responses to two questionnaires which were distributed to CIM members, government, professional associations, and educational institutions, formed the backbone of the Task Force position paper, which presents a shopping list of ideas and initiatives for consideration and to facilitation by the various organizations concerned.Tackling the image of the minerals industry is part of the answer to the careers crisis. On the positive side, the minerals industry provides the allure of a treasure hunt for young people and is seen as a significant contributor to the economy. It is understood to be well paying, provide good opportunities for advancement, individualism, and travel, and to be rich in esprit de corps. Enhancement of these positive aspects of the image can take place at all student age levels.Numerous initiatives tackle the negative aspects of the image. Young people perceive the industry to be environmentally damaging, which is the most crucial aspect that needs to be addressed. The industry is seen as still in the pick-and-shovel days and as a sunset industry that is running out of ore. Work in the minerals industry is perceived as dangerous and lacking glamour. And finally, the perceived remoteness of operations and exploration is seen as a drawback to a largely urbanized student group.Tackling young peoples' curiosity and interest in the minerals industry throughout grade school and encouraging postsecondary science and engineering students to enter the minerals industry by ensuring summer employment is the second part of the equation.The CIM Careers Task Force position paper develops strategy to attract and maintain interest of students in grade school, junior high, senior high school, and in post-secondary levels. The strategy outlines initiatives targetted at each of the educational levels and action plans to accomplish the objectives."

Jan 1, 1993

By Hans von Michaelis

"INTRODUCTIONThe renaissance in gold and silver recovery technology has continued to unfold and it is appropriate to review some of the useful new technologies as well as try to identify some of the industry's future needs and frontiers.The remarkable strengthening in the US dollar has resulted in a relatively low gold price in US Dollars of around $310/oz at the time of writing and silver at $6.25/oz. This general softening in the dollar prices and the recent confusion as to environmental compatibility of cyanidation tailings and effluents, has led to a slowdown in announcements of new operations. Another reason for the slackening off in the USA is that in the past few years a large part of the capital has come from oi I and gas companies that now seem to be losing interest in mineral ventures, and foreign investors for whom the dollar is becoming out of reach. In the author's opinion this represents an unprecedented window of opportunity.Elsewhere in the world where local currencies have weakened, the price of gold is at or close to its all time high.For example, in South African Rands, the gold price was R571.00/oz when the rand was US$1.47 and the gold price reached US$800. Now at US $309/oz and with the Rand at US$0.51 = Rl .00, the local gold price is R600. The price of si Iver in Mexican pesos is not much less than it was when silver reached US$50/oz. Gold, and silver prices in local currencies outside North America are still buovant and at levels where additional investment in new projects is more encouraging.Even in Canada where the dollar is worth about US$0. 75, this provides a smaller but significant cushion compared with US operations. Considering the present strength of the US dollar and even the Canadian dollar relative to many other gold producing countries, there should be significant investment opportunities at today's prices. Mining companies have started to descend on Brazil, for example, where in a matter of just a few years annual gold production has increased from 10 to 70 tons. In South Africa, a Canadian company backed by Swiss financing has been able to take over a Witwatersrand gold mining operation and is installing a huge new tailin9s retreatment plant to process about 1 million tons per month of tailings."

Jan 1, 1985

By P. R. Day, W. K. Webster

"The introduction of large boreholes underground initially involved taking the techniques of open-pit bench blasting to the production stope, but with deeper boreholes and narrower stopes more controlled techniques must be developed in order to maintain good stope walls and prevent dilution of ore or structural damage to pillars due to blasting overbreak. The points discussed are drilling accuracy and drill pattern, the relationship between open-pit wall control and underground mining, the varied explosives products and initiation devices available, and some of the many ways that variations in loading, such as deck charging, etc., can produce desirable results.IntroductionThe use of large-diameter blastholes for underground mining began ten years ago and today they are widely employed in a variety of orebodies and stope configurations. These big blastholes, which range in size from 4.5 to 8 inches in diameter, were originally employed in the same manner ' as open-pit bench blasts; that is, the stope was silled out to full width and all holes were drilled vertical and parallel. This was suitable for competent, massive orebodies, however the popularity of the big drills saw their usage in more narrow stopes, often with poor ground conditions. The dipping orebodies and small drill sublevels resulted in inclined drilling.Today, there is full-ring drilling of 4.5-inch holes. Some 6.5-inch holes are drilled up to 350 feet deep. A 350-foot borehole may contain 6000 to 7000 pounds of explosive. The detonation of this size of charge weight within the confines of an underground stope can have considerable effect on the stability of stope walls and adjacent pillars. Obviously, precautions must be taken to minimize the damage which would result from the large charge weights possible with these big boreholes."

Jan 1, 1982

By F. Charette

The paper reviews recent investigations of the impact of corrosion on the performance of both plain and coated Swellex rock bolts. It addresses the problems associated with estimating and predicting corrosion rates of friction bolts, and based on field data it suggests an empirical relationship to predict corrosion rates. A review of the necessary qualities for a protective coating leads to recent experience with coated Swellex bolts that suggest that they can contribute to extending the useful life of Swellex bolts in potentially corrosive environments.

May 1, 2004

By Ralph Harris, Qi Xia

"Gold cyanidation rates are known to be limited by the rate of oxygen dissolution in the cyanidation tanks. The effect of solids loading on the oxygen dissolution rates is not obvious and the results of previous studies are ambiguous. The present paper presents an analysis of oxygen dissolution rates using a ""spent"" commercial gold slurry diluted to various levels of solids loading. It was found, in an 170 litre stirred tank reactor using an inverted cone sparger, that under certain high loading conditions, there was a decrease of as much as 50 %, i.e., there was a halving of the rate of oxygen dissolution as compared to that in clean water. In particular, it was observed that, due to gas flooding of the impeller, there was a drop in kLa even with an increase of gas velocity. Gas holdup reached a maximum value of only 1.7 %. The total power consumption was between 0.06- 0 .10 kw/m3 within the range of gas velocity before flooding occurred. The decrease in oxygen dissolution rate with increased solids loadings is believed to be mainly due to the increase in the apparent viscosity which reduced the turbulence and shearing effect and resulted in larger bubbles and hence reduced the reaction area a. The interrelations between solids loading, gas holdup, flow pattern, power consumption, and liquid mass transfer coefficient are discussed.IntroductionThe reactors generally used in gold cyanidation are Stirred Tank Reactors (STR). Compared with other types of reactors like fluidized bed reactor and column reactor, STR is of particular importance due to its wide application in industry. It is reported that the stirred tank reactor is used for more than 50 % of the world's chemical production (Xu and McGrath, 1996)."

Jan 1, 1997

By W. R. Hargrave

"Mining OperationsOre will be mined by open pit techniques. Because of the high grade of the deposit and the low strip ratio, mining rates are small relative to most other open pit operations.The ore deposit is located in the valley of the main fork of Red Dog Creek. The bulk of the deposit is located on the southwestern flank of the creek, but mineralization does traverse the creek in both the north and east directions.Erosion has exposed the orebody in a number of locations, and has resulted in oxidation of the mineralization closer to the surface. Although much of this oxide material is very high grade, it leaches readily and, at least in the initial phases of the operation, will be stockpiled and not treated in the concentrator.During construction, 2.3 million mt. (2.5 million st.) of overburden and waste will be stripped from the orebody to expose ore for initial operations. Competent non-mineralized waste will be used to build roads and waste dumps, but the bulk of material removed consists of oxide or ice-rich soils and weathered rock which is not suitable for construction.The annual ore mining rate will be 1.9 million mt. (21. million st.). The strip ratio will start off at 1.2 to 1, falling to 1.0 to 1 by year 5 and ultimately to 0.8 to 1.Bench heights are set at 7.6 m (25 ft). Pit slopes will vary depending on the material present in the wall. The slope, through competent waste and the sulphide package, was set at 45 degrees. This is flattened to 26 degrees (i.e. 2: 1) through overburden and Upper Kivalina shales. The Kivalina Shales are an ice-rich shale whose carbonate matrix has been leached out and which exhibits little or no strength as it thaws. In addition, a 100 ft containment berm will be left in the wall below overburden and Kivalina."

Jan 1, 1989

By Geir M. Haarberg

Electrochemical techniques, mainly linear sweep voltammetry and potential step chronoamperometry, were used to study the behaviour of dissolved phosphorus species in cryolite-alumina melts, The presence of AIPO4 or Na3PO4 gave rise to voltammetric current waves due to electrode reactions involving phosphorus species at potentials where dissolved alumina is stable in cryolite melts, Diffusion kinetics for dissolved P(V) species were studied, Data from industrial cells were used to determine mass balances for phosphorus, For cells being fed with secondary alumina, more phosphorus tends to end up in the produced metal, Laboratory experiments to study the effect of phosphorus in the bath on the current efficiency for aluminium were also carried out.

Jan 1, 2004

By D. D. Hogarth

"IntroductionThe Hull iron range, comprising the Forsyth, Scott , Baldwin and Lawless properties (Fig. I), is in Gatineau Park, on the outskirt s o f the city of Hull , and about 6 miles (10 kilometres) northwest of the Federal Parliament Buildings.The deposits have been known many years and described numerous times, although the history has been treated lightly in former publications. Total ore shipments have been calculated at 122,700 long tons, of which over 80% were mined before 1900 and 74% in two brief periods: 1870-74 and 1880-82. It is surprising that the period 1870-74 has been overlooked by most authors and 1880-82 ignored altogether. More surprising, the essential data for these two periods are contained in manuscripts of the Robert Bell collection, which must have been available to officers of the Geological Survey o f Canada.The period 1801-1874 ha s already been covered by the writer in ""Pioneer mines”, but much information has come to light since publication. The present paper is therefore based o n new data and a fresh appraisal. However, little additional data were found for the early history (1801-1854) or for the legal cases involving A.H. Baldwin, and these parts were mainly summarized from the relevant sections of the above-mentioned publication.GeologyThe ore deposits are all situated somewhat below the middle of a graphitic, calcitic marble horizon, here folded into a northeast-plunging synform. The Forsyth, Scott and Baldwin deposits are on the south limb of the synform; the Lawless is on the north limb. The marble is underlain by three non-carbonate groups: biotite gneiss with interlayered quartzite (top), granite gneiss and skarn (middle), and biotite-garnet gneiss (bottom). Below these groups is a lower horizon of graphitic, calcitic marble. The whole sequence is Precambrian and has been subjected to high-grade (Grenvillian) metamorphism, but, in the north, is cut by an unmetamorphosed Cambro-Ordovician diabase dyke. For further information, the reader is referred to the summary by Baird."

Jan 1, 1983

By S. Jeon, T. H. Kim

"Understanding the frictional properties of discontinuities is crucial to ensure the stability of underground structures. In particular, the frictional behavior at depth depends on the complex interaction among mechanical, hydrological, thermal and chemical characteristics and their coupled effects. In this study, a series of triaxial compression tests were carried out to investigate the behavior of rough shear surface of synthetic rocks. The frictional behavior showed little variation at different confining and water pressures. The test results were analyzed using Coulomb’s failure criterion. In addition, numerical analysis was carried out using PFC2D to simulate the test.INTRODUCTIONUnderstanding coupled behavior of rock at depth is of great importance in design, construction and operation of underground structures such as a disposal facility of radioactive waste, hot dry rock geothermal system and oil reservoir. In particular, many uncertainties are involved in characterizing deep rock mass deformation in the designing process and interactions among fluid flow of groundwater, high temperature and stress disturbance should be considered. Many independent studies have been carried out to investigate the thermal, hydro, mechanical and chemical coupled effects in numerical and experimental methods. They include the researches by Lockner, Summers, Moore and Byerlee (1982), Jafari, Amini Hosseini, Pellet, Boulon and Buzzi (2003), Tembe, Lockner and Wong (2010), Lee, Lee and Jeon (2012), Indraratna, Premadasa, Brown, Gens and Heitor (2014)."

Jan 1, 2015

By Gérald Riverin, Bernard Salmon, Marlo Gagnon, Réemi Asselin, Alain Cazavant, Michel LaBrie

"The Ansil deposit is located in the Noranda mining camp in the southern part of the Abitibi greenstone belt. /twas discovered in 1981 and production began in 1989 with proven reserves of 1.58 Mt grading 7.2% copper, 0.9% zinc, 26.5 glt of silver and 1.6 glt of gold. It is centered at a depth of 1.3 kilometre and represents one of the deepest ore discoveries ever made from surface.The deposit consists of a single massive sulphide lens located at the contact between the Northwest Rhyolite and the Rusty Ridge Andesite. The lens strikes north-south and dips 50° east. The thickness of the lens may reach up to 35 m and can change very abruptly both along strike and along dip. The maximum thicknesses of the sulphide lens are reached in its upper (western) and at its lower (eastern) edges, thus giving the deposit its present shape of two sulphide domes connected by a thinner central portion. The lower dome is underlain by a thick accumulation of massive magnetite which may reach 10 to 15m in thickness. The upper and lower domes are underlain by two distinct pipe-shaped zones of stringer and disseminated sulphides which merge with a larger stringer zone at depth.The Ansi/ deposit displays strong relationships between its morphology and the distribution of metals. Hydrothermal alteration consists of chloritization and sericitization. Chlorite alteration is closely associated with stringer sulphide mineralization while sericite is developed in diffuse zones bordering the chloritic zones. Unlike other similar deposits, the Ansil deposit is characterized by very extensive alteration and sulphide mineralization in the hangingwall of the massive sulphides. Several features of the deposit are consistent with an origin from a submarine hydrothermal system which was particularly long-lived, and which thus promoted the build-up of very high fluid temperatures with extensive replacement (and enrichment) of pre-existing sulphides after their original deposition onto the seafloor."

Jan 1, 1990