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By Ning Shi

This paper suggests an alternative design approach for an innovative shovel dipper, for use in ground conditions where cutting of virgin ground rather than scooping of blasted material is required. Not only does the new design have an optimized dimension ratio (width:height:depth) and attachment arrangement (angle, position), but also a non-linear pro¯le in 2D and 3D. The approach is based on the simulation of a shovel's duty cycle to verify a pilot dipper model. In order to achieve a realistic simulation that could be used to evaluate a dipper design, the model is e®ectively a descriptor of actual shovel activity under soft ground conditions. The shovel geometry, motion and operation, with an emphasis on digging and dumping kinematics and dynamics are the principal elements of the simulation. The simulation considers a fresh face location, repeating tucking, digging and dumping swing motions within the geometric range of the machine, ending when no more face material remaining within reach without re- positioning. The simulation yields digging force, friction force, trajectory, ¯ll time, ¯ll factor, etc, which may be integrated into two basic considerations: power draw (output) and volume delivered (production), as indicators of dipper performance. The simulation has been used as a tool to modify an existing dipper design, prior to looping further simulation cycles. Ultimately, an optimized or totally-new-concept shape is realized. A prototype dipper as a fractional scale model will be built to verity the performance under actual mining conditions.

May 1, 2004

By William H. Schiffbauer

This report details a microcomputer-based control and monitoring network that was developed in-house by the U.S. Bureau of Mines and installed on a continuous mining machine. The network consists of microcomputers that are connected together via a single twisted-pair cable. Each microcomputer was developed to provide a particular function in the control process. Machine-mounted microcomputers, in conjunction with the appropriate sensors, provide closed-loop control of the machine, navigation, and environmental monitoring. Off-the-machine microcomputers provide remote control of the machine, sensor status, and a connection to the network so that external computers can access network data and control the continuous mining machine. Because of the network's generic structure, it can be installed on most mining machines.

Jan 1, 1993

By Jeremy Stone, Yiming Sun, John Stolz

The Courthouse Commons Tunnel facilitates the secure transfer of inmates between the County Jail and State Courthouse across a city block in downtown San Diego, California. This shallow tunnel was excavated using the Sequential Excavation Method in soft ground. It passes under 8- and 10-story buildings with a foundation cover of 6 feet, and crosses the active San Diego Fault with a design offset displacement of 18 inches. In this paper, key design challenges of tunnel construction are presented: limiting building settlements without using underpinning of building foundations and incorporating an oversized seismic section with seismic joints and crushable backfill

Dec 1, 2022

By A. Baldwin

Reports technical progress in designing four machines to be used in mining coal underground, applying innovative concepts at the design stage (instead of add-ons). A study phase was followed by design activity, including calculations supporting the designs. Scale models of three machines were built, and a full-scale mock-up of the conventional loader was used to measure human factors parameters.

Jan 1, 1976

By Dudley L. Davis, E. C. Peterson

INTRODUCTION THE Darwin District is 30 miles east of Olancha which is 220 miles north from Los Angeles via U. S. Highway No. 6. The ore deposits occur in the Darwin hills that have been elevated above the Darwin Plateau by typical basin and range-type faults. Some of these faults have been active quite recently as shown by the displacement of Quaternary (?) basalt flows and the rejuvenation of erosion in Darwin wash. The ore bodies occur as fissure fillings and replacement of favorable beddings in a thick series of Paleozoic limestones, dolomites, shales and quartzites. Rich oxidized lead-silver ores were discovered in the early seventies. By 1875, Darwin had a population of about 5000, and by 1880 several small mills and smelters had been built. Early exhaustion of surface ores, the isolated location of the district, and fluctuation of metal prices caused intermittent operations until World War II. The district production is estimated at about $3,000,000 prior to 1900 and perhaps $4,000,000 between 1900 and 1945 when Anaconda purchased the major producing mines. For the past two years, daily production has averaged 75 tons of direct shipping and 150 tons of milling-grade ore. At present, 300 tons of mixed oxide and sulphide ore are treated by flotation, the oxidized lead minerals being activated by addition of sodium sulphide after galena and sphalerite have been recovered from the circuit. Extraction averages 85 pct of the lead, 80 pct of the silver, and about 33 pct of the zinc in a bulk concentrate. The mill is designed so that minor changes permit selective flotation of pyritic lead-zinc ores encountered at depth. GENERAL GEOLOGY The oldest rocks in the Darwin hills are a series of Paleozoic limestones, dolomites, shales and quartzites probably Pennsylvanian in age. These rocks have been intruded on the west by the Coso granite batholith and on the east by a granodiorite stock. Numerous sills and dikes grading from orthoclase granite to gabbro are exposed in the underground workings. The sedimentary rocks have been considerably folded and faulted, the most prominent structure being a northwest pitching anticlinal fold, the crest of which lies just west of the ridge line of the Darwin hills. The east limb of this fold has been intruded by the granodiorite stock and east of the stock the sediments show several closely spaced anticlines and synclines. The minor flexures on the west flank of the major fold are structurally important in localizing the ore in the Defiance and Essex mines of the Darwin group. There are three principal systems of faulting and fissuring, most of which are post-intrusive and premineral in age, with minor amounts of postmineral movement. The Darwin tear fault is the largest, most persistent fault in the district. It strikes N 60 to 95°W, dips steeply south and is traceable for about 1o miles. It is a normal

Jan 1, 1947

By Robert Vinson

This article examines the spatial variability of dust concentrations within a coal miner?s breathing zone and the impact of sampling location at the cap lamp, nose, and lapel. Tests were conducted in the National Institute for Safety and Health Pittsburgh Research Laboratory full-scale, continuous miner gallery using three prototype personal dust monitors (PDM). The dust masses detected by the PDMs were used to calculate the percentage difference of dust mass between the cap lamp and the nose and between the lapel and the nose. The calculated percentage differences of the masses ranged from plus 12% to minus 25%. Breathing zone tests were also conducted in four underground coal mines using the torso of a mannequin to simulate a miner. Coal mine dust was sampled with multi-cyclone sampling cans mounted directly in front of the mannequin near the cap lamp, nose, and lapel. These four coal mine tests found that the spatial variability of dust levels and imprecision of the current personal sampler is a greater influence than the sampler location within the breathing zone. However, a one-sample t-test of this data did find that the overall mean value of the cap lamp/nose ratio was not significantly different than 1 (p-value = 0.21). However, when applied to the overall mean value of the lapel/nose ratio there was a significant difference from 1 (p-value < .0001). This finding is important because the lapel has always been the sampling location for coal mine dust samples. But these results suggest that the cap location is slightly more indicative of what is breathed through the nose area.

Jan 1, 2007

By D. S. Salonine

Aluminum alloys are widely used in modern industry. Tubes and hollow shapes give great opportunities for structural purposes as well as fluid transport due to their stiffness and lightness, Extrusions on a mandrel or through a bridge die, that requires splitting of the billet with re-welding, produce hollow shapes with varied contours, fins and multiple cavities. Moving and stationary mandrels, mandrel lubrication, tooling for ribbed-tube heat exchangers, and for drilling pipes are considered. Bridge dies can be classified by the bridge position relative to the die face, by mandrel support structure, and by assembly type, The main parameters influencing the quality of the die-welded seams are considered, The difficulties of extruding various alloys through bridge dies are discussed in terms of metallurgical factors, Some approaches to the calculation of the stresses in a bridge are presented.

Jan 1, 2005

By Amauri Garcia, Rodrigo Valenzuela Reyes, Noé Cheung, José Eduardo Spinelli, Leonardo Fernandes Gomes, Rafael Kakitani

"The present research work deals with directional solidification (DS) of both Al-15wt.%Si and Al-15wt.%Si-1.5wt.%Mg alloys and further characterization of the related microstructures. The growth of refined primary Si and refined eutectic is well-known as positive in order to improve mechanical properties of the Al-Si based alloys. Alloying is also an effective method to strengthen the Al-Si based alloys, in which Mg is considered an important alloying element. However, lack of investigation regarding the effects of Mg on microstructure of these alloys is noted. So, in the present research work emphasis is given on both dendritic and eutectic growth being affected by solidification kinetics (V-growth rate and G-thermal gradient) during transient directional solidification. Experimental evolutions of microstructural spacing of both alloys have been determined which becomes possible to understand the effects of Mg coupled with the effects of growth rate on the final microstructural arrangements. A direct comparison of the tensile mechanical properties obtained for the alloys is also performed. It is shown by these correlations that the addition of Mg generally improves the tensile mechanical resistance with a minor decrease in ductility. Furthermore, the Scheil solidification path of the ternary Al-Si-Mg alloy was determined using the computational thermodynamics software Thermo-Calc, resulting in the following sequence of precipitation: Liquid-Si-a (Al)+Si- a(Al)+Si+Mg2Si. This sequence is compared with the experimental microstructure findings.INTRODUCTION Al-Si alloys containing from 4wt.% to 22wt.% Si comprise more than 90% of all Al-based castings. Parts manufactured with these alloys have a wide range of industrial applications due to their excellent castability, crack resistance, good corrosion resistance, good weldability, low density and high strength (Bray, 1976; Zolotorevsky, 2007; Reyes, 2017). Hypereutectic Al-Si alloys are widely used and researched in the automotive and aerospace sectors due to the low coefficient of thermal expansion, resistance at high temperatures, good wear resistance and high strength (Reyes, 2017; Tebib, 2013). Above the equilibrium eutectic composition (~12.5wt.%Si) the amount of primary Si particles becomes significant (Lasa, 2003). In the place of conventional hypoeutectic Al–Si, there is growing interest in hypereutectic Al–Si alloys as a candidate material for the high-quality engines because a higher volume fraction of silicon may bring about superior properties (Matsuura, 2003)"

Jan 1, 2017

By Goodman, Richard E.

A complete rational analysis for design of excavation slopes and loaded rock masses is a desirable but perhaps unattainable goal. Irregular external and internal boundary conditions, poor understanding of failure criteria for large masses of rock, capricious material properties, and the importance of indeterminate forces and inaccessible and virtually un- sampleable rock defects emphasize the importance of experience in this aspect of rock engineering. The experience must be correlated with geological factors. In certain regions the accumulation of such experience through the observation of existing rock slopes in various formations constitutes an important aspect of studies for design of rock excavations.

Jan 1, 1969

By Saulo Brinco Diniz

O presente trabalho buscou explorar a aplicação da nanoindentação instrumentada na caracterização microestrutural e mecânica de materiais metálicos. Para isso foi utilizado um ultramicrodurômetro (Shimadzu, modelo DUH–211S) e um microscópio (Olympus, modelo BX51M) a fim de analisar uma chapa laminada a quente de uma liga de alumínio 7475-T7351. De acordo com algumas das possibilidades apresentadas, pode-se concluir que a nanoindentação instrumentada é uma ferramenta poderosa para a caracterização de materiais metálicos.

Aug 16, 2017

By I. Mikov

Established in the 60-ies, the Zlatna Panega quarry is a cement raw materials quarry supplying 95% of the needs of the Zlatna Panega Cement Plant with limestone, marl and other silica-aluminates. The two major types of raw materials are formed by accordingly dipping strata of Upper Jurassic limestones and lower Cretaceous marls. Between them there is a ?transition-zone? or ?contact-zone? of a high-silica content layer, about 5-m thick, defined as ?flint? by investigations including spot sampling throughout the quarry. For many years this ?contact-zone? layer was neglected due its negligible thickness. Further, with the increasing demand on the quality of the raw materials feed to the Plant and the focus on variability of the chemical and mineralogical components, it was decided not to mine any of the parts of the quarry contaminated by this material, for about three years. The latter had an impact on the availability of operating benches that could result in a substantial decrease in the total recoverable re-serves of Zlatna Panega, particularly with respect to marls. There were considerations for resorting to a partial, selective excavation of the quarry pit with a reduced lifetime for the lime-stones and re-opening of an other (currently in-active) marl quarry at a distance of 6 Km from the Plant. The Quarry Team of the Zlatna Panega quarry was assigned to study the problem. The ?contact? layer was duly confirmed with systematic geological (including mineralogy) studies, statistical analysis of available data, surface sampling and shallow exploration drills, resulted into distinguishing a third type of reserves and their credible subsurface delineation by means of geological 3-D modeling and quarry design. A new quarry design was finally elaborated with a view of providing flexibility in mining, utilization of the total volume of all available reserves and maximizing the mine life of Zlatna Panega quarry. An industrial test took place in December 2005, by using the contaminated parts of the quarry (co-mining of the ?contact-zone? materials) at a contribution of 15-20% in the raw materials mix, as dictated by their contribution in the total recoverable resources of the quarry. The purpose was to investigate the viability of this solution ? in line with improved quarry planning ? without compromising the quality of cement production and the efficiency of Plant Operations. Results were overall successful.

Jan 1, 2006

By P. R. Bradley

This paper is one of a series , dealing with mining methods and costs , sponsored and published by the U. S. Bureau of Mines . Papers of this series are written by engineers and executives of mining companies , at the solicitation of the Bureau , and in accordance with an outline prepared by Bureau engineers , for the purpose of securing uniform presentation and conformable data . The property of the Alaska Juneau Gold Mining Co. is situated near the city of Juneau , Alaska , in what is known as the Harris mining district . Wholesale mining operations have been adopted on a large scale and 10,000 to 11,000 tons per day of gold- bearing ore are mined and sent to concentrators near Juneau . In addition to gold , the ore yields 0.6 ounce of silver and 13.0 pounds of lead to each ounce of gold recovered .

Oct 1, 1929

By A. Muwila

Hercules? is a low nickel austenitic stainless steel developed at Mintek that has a typical composition of 9 wt% Mn, 0.05 wt% C, 2wt% Ni, 0.25 wt% N and 16.5 wt% Cr. A more corrosion resistant version of Hercules? (Hercules? B) with 0.5 wt% Mo has also been developed. Potentiodynamic tests performed on Hercules? B in a 5wt% sulphuric acid solution showed it to have improved corrosion resistance comparable to that of AISI 304. The effect of a varying Mn content on the corrosion resistance of Hercules? B has also been investigated and the results discussed in this paper. From the corrosion test results, it is clear that decreasing the Mn content of Hercules? B increased the corrosion rate, while increasing it decreased the corrosion rate. Keywords: austenitic stainless steel, % ferrite, molybdenum, manganese, nitrogen, electrochemical corrosion tests, potentio-dynamic scans, microstructure, chemical analysis.

Jan 1, 2007

By G. S. Rice, H. P. Greenwald, H. C. Howarth

"""Rock-dust barriers""5 as they are termed in this country, are for the purpose of confining a coal-dust mine explosion to the limited area in which it originates. These barriers were first tested in 1910-1911, with favorable results under the conditions of test, at the French official gallery which was then at Lieven, Department of Pas-de-Calais. Shortly afterwards the Bureau of Mines in the course of its investigation of all practical explosion-prevention methods tried barriers in the Experimental Mine near Bruceton, using the primary form of simple fixed cross shelves 20 inches wide extending over the passageway and laden with rock-dust. The Bureau termed them “Taffanel barriers"" in honor of the director of the Lieven testing station. The trials were made in conjunction with tests of explosibility of different coal-dusts.Experience showed that although the principle of barriers had merit when they were used for secondary defence, the primary form was uncertain in effectiveness. This led the senior author to design mechanically discharging barriers to be operated by the compression air waves which precede the flame of an explosion. For the better understanding of the principal involved, it is pointed out that the advance air waves are what make a coal-dust explosion possible by stirring up the coal-dust from the walls and floor of the passageway. If a barrier can throw inert dust into the air to form a cloud as dense or denser than that formed by the coal-dust, it will neutralize the explosiveness of the coal-dust, and the flame of the explosion will be extinguished. When the flame ceases, the pressure dies away in a short distance if the 'area that had been traversed by the explosion is not large."

Jan 1, 1930

By Elaine Araújo

Since the ancient times, clays were used as decolorant material for various types of oils. These clays were called ?decolorant clay?. They have the property to decolor dye materials present in mineral oils, plants and animals. Biofuel is a fuel derived from biomass of live organisms. As biodiesel is produced from renewable sources, the generation of employment due to industrial scale production may cause a reduction in the dependence on foreign diesel importing, as well as the reduction of air pollution by the addition of biodiesel to diesel. This study aimed to develop a technological process to decolor post- consumption oil to be applied as biofuel. The results were characterized by techniques of XRD (X-ray diffraction), X-ray fluorescence and FTIR (Fourier Transform Infrared). It was observed that the post-consumption oils presented a higher decoloration result after treatment with the Brazilian clay.

Jan 1, 2009

By Alexandra Kozak, Rodrigo Costa, Bob Fukuhara

"The Jacobina project in Bahia, Brazil commenced operations in 2004 with a design capacity of 4,200 tpd. A project development plan to increase plant capacity to 6,500 tpd will be discussed. The project included an evaluation of the existing circuit and addressed bottlenecks in the crushing, milling, sedimentation, leaching and tailings transport. These circuits and the methodology used to provide higher capacity will be presented.INTRODUCTIONThe Jacobina mine is located in the state of Bahia in northeastern Brazil approximately 330 km northwest of the state capital city of Salvador and 9 km from the town of Jacobina. The Jacobina Mine (Figure 1) is owned by Jacobina Mineração e Comércio, a wholly owned subsidiary of Yamana Gold Inc.The gold mineralization of the Jacobina mine is hosted within quartz pebble conglomerate reefs of the Serra do Córrego Formation which together with the Rio do Ouro Formation forms the Serra do Jacobina mountain chain.The Serra do Jacobina mountains have been mined for gold since the late 17th century. Since the 1970’s, the Jacobina mine has been operated by Anglo American, Williams Resources Inc., Desert Sun Mining Inc. The mine is currently owned by Yamana Gold Inc.In December of 1998, operations at Jacobina were suspended and the property was placed under care and maintenance. Desert Sun Mining Inc. began exploring the property in 2002 and eventually purchased the Jacobina mine in 2003. In 2003, a feasibility study was completed that evaluated the economics of re-developing the mining operations and expanding gold production. In 2004, refurbishment and re-development of the mining operations began and the milling facility throughput capacity was expanded from 1.08 to 1.512 Mtpy (3,000 to 4,200 tpd). The milling operations were commissioned in the 1st quarter of 2005 and commercial production was declared 1 July 2005. In April 2006, Yamana Gold Inc. acquired the Jacobina mine through its acquisition of Desert Sun Mining Inc."

Jan 1, 2008

By Jay Nopola, Christopher Johnson, Matthew Minnick, Erik Hemstad, Erik Walega

Mining data collection, storage, and interpretation methods have progressively changed over time. Data collection, for the most part, has transitioned from handwritten notes and logs based on manual gauge readings to real-time data streaming through instrumentation capable of directly communicating with site-based data historians or cloud storage. Data collection and storage have had to adjust commensurately with the volume of data, leading to more complex database architecture. Geoscience interpretation methods have also changed; however, the first goals of modeling and understandings from first principles remain the same and are typically deeply rooted in historical academic work. Machine learning methods are becoming more common, available, and implemented by industry and practitioners. Despite the wide accessibility of machine learning methods, the population of geoscience subject matter experts in the underlying theory of this analysis type is limited. This form of analysis, therefore, must be conducted carefully and in conjunction with subject matter experts, on both machine learning theory and the field it is being applied to. This paper aims to provide background history on data analytics and machine learning, current methods and practices, and high-level geoscience case study examples, as well as take aways regarding the mining industry, potential pitfalls specific to geosciences, and possible perspectives on the direction of artificial intelligence in the future.

Jun 25, 2023

By H. S. Martin

The Phosphate Recovery Corporation operates three flotation plants, Nos. 1 and 2 concentrators about three miles northeast of Mulberry, Florida, and No. 3 plant at Wales, Tennessee. These plants represent the first commercial phosphate flotation operation and are also believed to be the largest nonmetallic flotation operation in the world at the present time. The details of this paper will be confined to plant No. 2, this being the newest and largest concentrator in Florida, and the flow sheet being practically the same as at plant No. 1. The No. 3 plant has been operated but a short time and has been shut down since December, 1932, on account of the decrease in phosphate rock production. The phosphate washers usually are located centrally on a known deposit so that about two hundred acres of ground can be mined economically to each washer location. The washers are moved to new areas when the distance becomes too great for economical pumping. The flotation plants are built either adjacent to a washer, so that current debris may be utilized, or on the site of a former washer where there is sufficient accumulated debris available for mining, and the flotation plants must also be moved from time to time. Most of the water used in the Florida flotation plants is recovered after passing through a circulating system where most of the fine suspended matter is settled out, but some make-up water is obtained from deep wells near the plant. Power is obtained from the Tampa Electric Co. through the distribution facilities of the International Agricultural Corporation. Flotation concentrate is hauled from the plant by trolley over the International Agricultural Corporation&apos;s trolley system, to the drying plant at Prairie, one mile northwest of Mulberry. Ore Treated In the pebble phosphate district of Florida, the phosphate mineral, or collophane, is usually found in horizontal beds of varying thickness

Jan 1, 1935

By A Parry, C Fitzmaurice

After conducting laboratory ore sorting testwork on samples of a low grade nickel ore stockpile at Western Areas’ Flying Fox nickel mine, a mobile crushing, screening and ore sorting plant was located adjacent to the stockpile. An initial two month trial of the ore sorter program proved successful and was extended to process the entire Flying Fox low grade stockpile in a further four month campaign. A total of 167 660 t of low grade ore was processed, providing highly upgraded feed trucked 26 km to the Cosmic Boy concentrator. A more than three-fold grade increase was achieved on ore sorter accepts. The moderately upgraded fines that by-passed the mobile ore sorter were also subsequently blended into plant feed. This paper describes the mineralogy of the Flying Fox low grade ore, the mobile ore sorting campaign and provides some commentary on the economic and environmental benefits achieved in the ore sorting campaign. The ore sorting campaign demonstrated the benefits of being able to utilise mobile ore sorting equipment temporarily located adjacent to sub-economic low grade stockpiles in order to effectively treat these stockpiles and produce viable plant feed.CITATION:Parry, A and Fitzmaurice, C, 2018. The upgrading of low-grade nickel ore stockpiles at Western Areas Ltd Forrestania operations, using a mobile ore sorting plant, in Proceedings 14th AusIMM Mill Operators&#39; Conference 2018, pp 541–550 (The Australasian Institute of Mining and Metallurgy: Melbourne).

Aug 29, 2018

By K. Schimann, H. D. Knipping, J. P. Fouques

"RESUMELe gisement d &apos;uranium de Cigar Lake, dans la région de l&apos;Athabasca au nord du Saskatchewan, fut découvert en mai 1981 par Cogema Canada Ltée, opérant pour Ie compte de la ""Waterbury Lake Joint Venture"".Le corps minéralisé. qui est dépourvu de toute expression directe en surface, est situé a la discordance entre les met sédiments du wottaston Group (Protérozoïque inférieur ou Aphébien) et les grès de l &apos;Athabasca (Protérozoïque moyen ou Hélikien), à une profondeur de 410 a450 m.Fin 1984, Ie gisement était reconnu par 105 sondages minéralisés repartis sur une longueur de 1800 m, pour une largeur comprise entre 25 et 105 m. 11 se présente sous forme d’une lentille aplatie de 5 a30 m de puissance, et montre une remarquable continuité d&apos;ensemble. Une ride ou bombement topographique de la discordance est associée au gisement surtoute sa longueur.A l&apos;échelle régionale, le corps minéralisé à est associe à un corridor structural d’orientation est-ouest, a l&apos;intérieur duquel des facies particuliers aténdance blast mylonitique sont développes dans les formations métapolitiques agraphite du socle métamorphique. Il est entouré par un halo d&apos;altération très important, caractériser Ie développement de minéraux argileux alumino-magnesiens (illite-chlorite).La minéralisation est située, pour la plus grande part, dans les grès d&apos;Athabasca, et se compose essentiellement d&apos;uraninite et de sulfo-arseniures de nickel et de cobalt,De nombreux levés géochimiques et géophysiques ont été effectues dans la région de Cigar Lake. Aucune anomalie ne peut être associée directement au corps minéralise, mais la combinaison des données en provenance de plusieurs sources s’est révélée fort utile au niveau de l’interprétation géologique régionale et de la définition des cibles de sondages a l&apos;intérieur des zones reconnues favorables.Le gisement de Cigar Lake présente de nombreuses analogies avec plusieurs des gites classiques de la région de l&apos;Athabasca; il est caractérise en particulier par l&apos;intensité des phénomènes d’altération et la présence de minéralisations extrêmementriches.En 1984, les réserves géologiques globales estimées par géostatistique sur I ‘amas minéralise principal s &apos;élevaient a 110 000 tonnes d&apos;uranium, aune teneur moyenne de 12.2%, avec une précision de 25% à l&apos;intervalle de confiance de 95%.ABSTRACTThe Cigar Lake uranium deposit, in the Athabasca area of North Saskatchewan, was discovered in May 1981 by Cogema Canada LId., as operator of the Waterbury Lake Joint Venture. The deposit, which is devoid of direct surface expression, is located at the unconformity between the Lower Proterozoic (Aphebian) Wollaston Group meta-sediments and the Middle Proterozoic (Helikian) Athabasca sands tone, at a depth of 410 m to 450 m below surf ace.AI the end of 1984, the deposit had been defined by 105 mineralized holes over a length of 1800 m and a width of between 25 m and 105 m. It has the shape of a flat-lying lens 5 m to 30 m thick and shows a remarkable longitudinal and latera continuity from the information obtained to date. A well-defined bulge of the unconformity underlies the mineralized zone over its entire length.The deposit appears to be controlled by an east-west-trending structure within which a particular rock facies (""augen gneiss"") has developed in the graphitic metapelites of the Wollaston Group. It is surrounded by a strong alteration halo affecting both sandstone and basement, characterized by extensive development of Mg-A I rich clay minerals (illite-chlorite).The mineralization is hosted principally by the Athabasca sandstone, and consists mainly of uraninite and sulfo-arsenides of nickel and cobalt.Numerous geochemical and geophysical surveys have been carried out in the Cigar Lake area, and no specific geochemical or geophysical anomaly can be directly associated with the mineralized body, although there may be locally a good coincidence. However, a combination of several methods proved extre"

Jan 1, 1986