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By D. W. McDonald, L. M. Heaman, R. A. Creaser, T. Davies, T. Chacko, A. Simonetti

"The Three Bluffs gold deposit is located in the Committee Bay greenstone belt, which forms part of the Rae domain of the western Churchill province, Nunavut, Canada. Gold mineralization is hosted by iron formation of the Neoarchean volcanosedimentary Prince Albert Group, and is associated with silicification (quartz veining) and sulfidation of magnetite and other Fe-rich minerals. Conventional U-Pb zircon dating of a conformable dacite unit within the volcanosedimentary host-rock sequence and a crosscutting diorite intrusion confirm a ~2.7 Ga age for deposition of the supracrustal package. U-Pb monazite dates and Pb isotopic analyses of sulfides were obtained by laser ablation-multicollector-inductively coupled plasma-mass spectrometry (LA-MC-ICP-MS). A subset of U-Pb monazite (1813.8 ± 8.7 Ma) and Re-Os arsenopyrite (1822 ± 21 Ma) dates, combined with a Pb-Pb secondary errorchron age for pyrite and arsenopyrite (1829 ± 77 Ma), suggest that gold mineralization associated with sulfidation of the iron formation occurred at ~1815 Ma, prior to high-grade (upper amphibolite facies) tectonometamorphism in the Three Bluffs area (D2TB/(M2TB). An ~1815 Ma age for deposit formation is broadly consistent with evidence from elsewhere in the western Churchill province and to the southwest in Manitoba and Saskatchewan for a late Trans-Hudson (1.9-1.8 Ga) gold mineralizing event. The majority of U-Pb monazite ages form a second population at 1780.6 ± 4.2 Ma, similar to the age of the majority of Re-Os arsenopyrite analyses (1763 ± 11 Ma). These dates are thought to reflect the timing of peak M2TB metamorphism. 40Ar/39Ar dating of amphibole, biotite, and muscovite yielded plateau ages ranging from 1723.8 ± 9.0 Ma to 1710 ± 17 Ma, which are interpreted to record the timing of postpeak metamorphic cooling to below the respective closure temperatures for Ar diffusion in these minerals. Le gîte aurifère de Three Bluffs est situé dans la ceinture de roches vertes de Committee Bay, laquelle appartient au domaine de Rae dans l’ouest de la province de Churchill, au Nunavut, Canada. La minéralisation aurifère est encaissée par des formations de fer d’âge Néoarchéen appartenant aux roches volcanosédimentaire du Groupe de Prince Albert; la minéralisation est associée à de la silicification (veines de quartz) ainsi qu’à la sulfidation de la magnétite et d’autre minéraux riches en Fe.Les résultats de la géochronologie U-Pb conventionnelle sur une unité de dacite concordante au sein de la séquence volcanosédimentaire ainsi que d’une intrusion de diorite qui les recoupe indiquent que ces roches supracrustales ont un âge de ~2.7 Ga. Les âges U-Pb de la monazite ainsi que les analyses des isotopes du plomb des sulfures ont été obtenus par ablation laser (LA-MC-ICP-MS). Certains des âges U-Pb obtenus à partir de la monazite (1813.8 ± 8.7 Ma) et des âges Re-Os retournés par l’arsénopyrite (1822 ± 21 Ma), en association avec l’âge indiqué par une isochrone à données dispersées « errochron » secondaire Pb-Pb pour la pyrite et l’arsénopyrite (1829 ± 77 Ma), suggèrent que la minéralisation aurifère associée à la sulfidation de la formation de fer s’est formée vers ~1815 Ma, avant que l’événement tectonométamorphique (D2TB/(M2TB) de niveau élevé (faciès des amphibolites supérieures) affecte le secteur de Three Bluffs. Un âge de mise en place de ~1815 Ma pour ce gîte est compatible avec les données en provenance de l’ouest de la province de Churchill ainsi que plus au sud-ouest au Manitoba et en Saskatchewan qui indiquent la mise en place de minéralisations aurifères à la fin de l’orogénèse Trans-Hudsonienne (1.9-1.8 Ga).La majorité des âges U-Pb de la monazite constituent une seconde population formée à 1780.6 ± 4.2 Ma, ce qui est similaireLà l’âge obtenu pour la plupart des analyses Re-Os sur l’arsénopyrite (1763 ± 11 Ma). Ces âges reflètent probablement l’atteinte du pic métamorphique M2TB.La géochronologie 40Ar/39Ar de l’amphibole, de la bio"

Jan 1, 2009

By Nilce Alves Santos, Vânia Lúcia de Lima Andrade, Keila Lane Carvalho Gonçalves, Harold Wyslouzi1

"When confronted with the difficult decisions on advancing an exploration project to the feasibility and construction stages, it is important to know how various regions of the ore body will react in the milling and concentration processes. While bench scale test work is common and inexpensive, the results and information provided are somewhat limited due to the difficulty in accurately predicting the effects of recirculating middling streams or gradual changes in solution chemistry.Conventional Pilot Plants, processing 100 to 1,000 kg/hour of sample ore, provide the detailed engineering data required to develop a final process flowsheet and to size the equipment. They are, however, expensive to set-up and operate, and are really only viable for major projects that are well advancedIn the latter part of 1999, the Mineral Development Center at CVRD (MDC) purchased a new piece of mineral processing equipment which can run continuous flotation tests using drill core samples. To evaluate its performance, and to compare it with conventional testing methods, various types of flotation tests were carried out using two different types of copper ore. The limitations and advantages of open circuit and locked cycle bench tests, as well as the Mini Pilot Plant and the Conventional Pilot Plant were evaluated.Open circuit tests carried out at the bench scale only provide basic information. More complete and trustworthy information is obtained, in terms of the recirculation of flows and reaching a permanent and stable flotation regime, as the dynamics and complexity of the tests increases. The data obtained showed that the MPP’s metallurgical performance was equivalent to that of a conventional pilot plant."

Jan 1, 2002

By Garry Keizer

The Cortez gold mine is located in Lander County, NR, about 130 km (80 miles) southwest of Elko. Cortez Gold Mines (CGM) is a joint venture between Placer Dome US Inc. (60% operator) and Kennecott Corp. (40%). The claims that supply oxide and refractory ore feed to the Cortez milling facility are located in both Lander and Eureka counties. These include the Cortez and Horse Canyon deposits, all operated by the joint venture. Other deposits outside the CGM claim area include Fire Creek, Buckhorn, Gold Bar and Tonkin Springs. These deposits all occur along the Battle Mountain-Eureka Trend. History Mining in the Cortez district began in 1862 with the discovery of high-grade silver ores. Grades in the hundreds of ounces per ton occurred in an area 7 km (4.5 miles) southeast of the current CGM mill site. Underground mining through the Garrison and Arctic tunnels provided the bulk of the ore production between 1864 and 1895. To a lesser extent, the Mill Canyon area also supplied ore until 1930.

Jan 1, 1993

By S. Dessureault, J. Porter, M. Woodhall

Information and communication technology (ICT) is seen as a key source of future productivity improvements in mines. The information technology infrastructure (ITI) necessary to achieve these productivity improvements will come in the form of data integrated from multiple source systems throughout the mining value chain. Two pure approaches are available: supplier-controlled or operations controlled data structures; each strategy has its own advantages and disadvantages. Case studies involving the South African mining industry are used to demonstrate the advantages of using hybrid-controlled data structures. Depending on the level of operational control, new skills are also necessary to be learnt by mining professionals including: information engineering; creating consistent and quality data; and process improvement techniques that use the integrated data for improving the operation.

Jan 1, 2004

By E. A. van Wyk, M. R. de Villiers

"Mining companies strive to increase and maintain production, while simultaneously remaining competitive in the global economy. Furthermore, they must ensure workers’ safety and maintain good safety records. The use of virtual reality (VR) facilitates the development of tools and systems for various purposes that can improve knowledge and understanding of the work environment. VR is a rapidly growing technology that uses the ever-increasing power of computing to simulate real-world and imaginary environments and situations with a high degree of realism and interaction. The availability of 3D modelling tools and simulation programming engines that work effectively with a mid-range desktop PC and standard 3D graphics card, make VR technology viable and attractive for mainstream training applications. The design, development, and implementation of interactive VR training systems is proposed as an innovative approach to augment safety training. However, in order to assess the impact of such VR training systems it is of particular importance to determine the effectiveness of the design of such systems. This article proposes an evaluation framework for this vital purpose. This framework comprises criteria to assess VR training systems, specifically relating to usability, instructional design, VR systems design, and mining industry context-specific aspects. Although the framework was developed as an evaluation tool to assess effectiveness of the design of such systems, it can equally well be used as a set of design principles to inform the design of VR training systems for mining. IntroductionMining in South Africa has been the main driving force behind the history and development of Africa’s richest and most advanced economy (Coka, 2012). The South African mining industry is frequently criticised for its poor safety record and high fatality rate (Stoddard and Skweyiya, 2016). Inadequate or insufficient training is often cited as a root cause of accidents (Van Wyk and De Villiers, 2009; Tichon and Burgess-Limerick, 2011). Virtual reality (VR) is a rapidly growing technology that utilizes the ever-increasing power of computing to simulate real-world and imaginary environments and situations with a high degree of realism and interaction (Webber-Youngman and Van Wyk, 2013). VR is currently being used or investigated as a training solution in a variety of industries. VR technology has developed rapidly and costs have fallen to levels where it can now be considered for mainstream training applications. The availability of 3D modelling tools and simulation programming engines that work effectively with a mid-range desktop PC and a standard 3D graphics card, make VR even more attractive to mine training centres (Van Wyk and De Villiers, 2009)."

May 1, 2019

By C. S. Samis, D. P. Seraphim

In the presence of oxygen, galena is oxidized in an aqueous medium containing ammonium acetate in accordance with the following reaction: PbS + 1/2 0, + 2 NH~Ac -» PbAc, + So + 2 NH: + H2O. This reaction was studied in an autoclave under oxygen pressure by polarographic measurement of the concentration of lead ion in solution. Oxidation rate is parabolic. The reaction products are lead acetote and elemental sulfur, the latter forming a film on the galena crystal. Reaction kinetics appear to be determined by the diffusion of lead from the galena phase to the solution interface through the film of sulfur. RECENT applications of pressure leaching on a commercial scale have emphasized the metallurgical importance of the oxidation of sulfide minerals in aqueous media by oxygen under pressure. Research experience has shown that sulfates, thio-nates, and metal oxides are the products of humid oxidation of sulfide minerals in basic solutions. The metal oxides may be solubilized in the presence of a complexing ion.' Certain oxide minerals are also amenable to treatment by this type of oxidation.' Several kinetic studies have been made of reactions of this type. Stenhouse' found that pyrite (FeS?) oxidized in a sodium hydroxide solution to produce a soluble sulfate and an insoluble layer of iron oxide and that the kinetics of the reaction were controlled by oxygen diffusion through the oxide layer. Andersen' studied the oxidation of galena (PbS) in a sodium hydroxide solution under oxygen pressure. He found the lead and sulfur to be simultaneously oxidized to produce plum bite ions and sulfate ions, and that the reaction rate was proportional to the surface area of the galena. The kinetics appeared to be determined by the reaction of oxygen and water with the galena surface. In each of the above reactions the metal and sulfur components of the mineral were oxidized simultaneously and at equal rates. In the present study the alkaline medium has been replaced by an approximately neutral solution of ammonium acetate in which lead sulfate is soluble. Under the conditions no sulfate was produced and no sulfur could be detected in the solution. The metal component of the mineral was solubilized and the liberated sulfur remained as a film of elemental sulfur on the surface of the galena crystal. A kinetic study of this reaction was undertaken to establish the kinetic mechanism and to determine the rate controlling step. Specific reaction rates were determined by oxidizing crystals of galena of measured surface areas in an autoclave maintained at the desired temperature and oxygen pressure. The rate of reaction was followed by measuring the concentration of lead in the ammonium acetate solution with a cathode ray polarograph, employing stationary platinum electrodes incorporated in the autoclave. Experimental Materials and Equipment Crystals of galena obtained from Violamac Mines, Retallack, B. C., were selected for oxidation because

Jan 1, 1957

By Philippe Dumont

?Lay out of the tunnel section ?General ?Geology ?Tunnels methods ?Stations constraints ?Impacts on tunnels ?Design ?Programs

By O. Bernal, G. Velarde

Sociedad Minera Cerro Verde, majority owned by Phelps Dodge produces 200M lbs per year of LME Grade A copper from low cost leaching of secondary sulfides and SXEW processing. Central to the success of Cerro Verde has been the continuous improvement of leaching practices which currently yield over 80% recovery of the contained copper in the ore. This recovery has been achieved by careful attention to operational practices and leaching process fundamentals. This paper details the development of the concept of “Lixiviant Request Rate” where by solution is applied at an optimal rate for the grade, mineralogy, and the point in the leach cycle. Also paramount to the success of Request Rate technology has been the development of irrigation practices such as drip irrigation and irrigation grid design. These developments have ultimately resulted in improved copper production, decreased sulfuric acid and water consumption, decreased pumping cost, and more consistent PLS grades.

Jan 1, 2004

By J. A. Bakken, T. Magnusson, G. Sævarsdottir

This paper describes measurements of current and voltage done on submerged arc furnaces. The aim is to focus on and attempt to separate from one another the electric arc current and the current bypassing the arc through the charge. Toward this goal two measurement campaigns on AC-arcs burning on coke beds are ac-counted for. The first was done on a 150 kVA pilot furnace at SINTEF in Trondheim Norway, and the second one was done on a 48 MVA industrial furnace run by Icelandic Alloys in Iceland. The measurements were compared to simulations employing an advanced MFD arc model. The main results are that a coke bed does not necessarily behave as a linear conductor. However the warmer chemically transformed part of an operating Si-metal or FeSi furnace probably exhibits linear behaviour and passes a considerable fraction of the phase current, perhaps on some operating conditions, as much as 50%.

Jan 1, 2007

By H. L. Barwood

Luminescence excited by electron bombardment, or cathodoluminescence (CL), is a very useful tool in petrographic examination of rocks, minerals and ores. Differences in luminescence colors and intensities allow detection and delineation of mineral species and composition zones difficult to separate visually by normal polarized light microscopy. The cold cathode CL chamber at Indiana University is used with a binocular microscope that has interchangeable attachments for a normal film camera, a digital camera and a fiber optic spectrometer. This allows imaging of the specimens as well as limited spectrographic analysis of the emitted luminescence. The chamber on this CL unit is large enough to accommodate several thin sections, polished mounts, grain mounts or rock slices at one time. Luminescence petrographic techniques were used to study alkali syenites and carbonatites from the Arkansas. Alkali feldspars in the syenites reveal a history of growth, fenitization and replacement through color and intensity differences. Primary orthoclase luminesces bright blue and is often zoned with a duller blue overgrowth of microcline. Fenitization of the feldspars is demonstrated by dull to bright red luminescence and replacement veins of albite often have a bright yellow green luminescence. Late microcline and perthites from the syenite pegmatites have a dull yellow to orange luminescence. Easily visible on this background of feldspars are grains of apatite (yellow), fluorite (violet), zircon (greenish), sodalite (orange) and mosandrite (green). Complex pseudoleucite syenites from Magnet Cove, Arkansas show similar minerals but also include xenolithic quartz (violet), manganwollastonite (bright orange), benitoite (intense blue) and lorenzenite (green). Carbonatites from Arkansas contain a wide variety of calcite textures and intensities of luminescence. Grains of carbonatite in well cuttings are easily distinguished from sedimentary calcites by their complex “flame” luminescence and the frequent presence of euhedral apatite grains (yellow). Apatite crystals separated from the Arkansas River Valley carbonatites by acid digestion show complex zoning. The cores of these apatites are yellow luminescing due to CL activation by Mn enrichment while the rims are violet luminescing due to REE enrichment. Complex zonation between the cores and rims is easily visible using CL.

Jan 1, 2001

By Lance A. Roberts

Micropiles are commonly utilized for applications other than foundation retrofit. In bridges, for example, micropiles can serve as the permanent foundation elements or can be used in temporary support applications. In this paper, a case study on the use of micropiles for the 18th Street Expressway Bridge rehabilitation/repair project in Kansas City, Kansas is presented. In the project, micropiles were utilized for support of six temporary jacking structures, which allowed the bridge to be lifted while repairs were completed. A group of six micropiles was required to support each jacking structure. The required compressive service load per micropile was approximately 300 kips (1300 kN) and the settlement of the micropiles under the service load was to be limited to 0.5 in. (12.7 mm). Two field compression tests were conducted as part of the project. The field load test data was integrated within a soil-structure interaction capacity approach in order to analyze and permit the shortening of the design bond length for the production micropiles.

Jan 1, 2009

By William J. Campbell

Three types of X-ray analytical instrumentation were compared for applications in the secondary brass and bronze industry. The instruments were a conventional X-ray spectrograph, a portable X-ray spectrograph, and a radioiso-topic X-ray analyzer using balanced filters. The following two general applications were considered: Rapid identification for sorting scrap metals and quantitative analyses to provide guidance in the melting and casting of alloys. Twenty-three analyzed copper-base alloys were used as standards. Although the alloys varied widely in composition, matrix correction procedures were not necessary except for copper. The conventional X-ray spectrograph provides positive identification of the alloys and quantitative values for the six elements investigated--aluminum, copper, iron, lead, tin, and zinc. Equivalent results were obtained with the portable X-ray spectrograph for those elements whose characteristic X-rays are in the wavelength range of the instrument. The radioisotopic X-ray analyzer distinguishes certain groups of alloys and provides quantitative determinations for copper, lead, tin, and zinc. The sensitivity of the analyzer was marginal for the determination of small concentrations of elements of atomic number 26 or lower.

Jan 1, 1972

By Z. M. Zhang

Fracture grouting is a particular technique which can be used in soils and rocks with low permeability to increase groutability and penetration rates and to solve some special foundation problems by inducing limited and controlled zones of hydrofracture surrounding the injection source. The present paper describes the basic principles of hydrofracture and its application to grouting in deep foundations, and indicates some recognitions about the mechanisms and effects of fracture grouting.

Jan 1, 2010

By Paul J. Axtell

Self-hardening cement-bentontie (c-b) slurry walls were constructed as shear walls to stabilize the downstream slope of Tuttle Creek Dam near Manhattan, Kansas. The slope stabilization was required to protect the existing pressure relief well system located at the downstream toe of the dam. The wells require protection from slope deformation induced by liquefaction of the foundation sands during or immediately after the design seismic event. The shear walls are transverse to the axis of the dam, unreinforced, and relatively brittle members that may be exposed to relatively large shear strains, and possible cracking, during or immediately after shaking. An extensive laboratory investigation was conducted on recovered core samples to optimize the mix design and stabilization scheme. Furthermore, as is the topic of this paper, a portion of the laboratory investigation was to determine the large-strain, or post-peak, shear strength of the c-b material for use in limit-equilibrium slope stability analyses and numerical deformation modeling to assess the magnitude of permanent deformation caused by the design earthquake. These data may be beneficial to other projects that are considering the use of unreinforced c-b slurry walls for seismic retrofit purposes.

Jan 1, 2010

By Tim O’Neil

Caterpillar has introduced its 5090B front shovel, to work with 40 to 70 st (36 to 63 t) trucks. The new unit replaces Cat’s 5080 hydraulic excavator. The 5090B offers more engine horsepower, higher flow, greater digging forces, higher swing torque, faster swing speed and more drawbar pull than its predecessor. It can also handle larger bucket sizes than the previous model. These improvements enhance productivity and make the 5090B a high-volume material handler for hard rock and aggregates producers.

Jan 1, 2003

Factors of importance in the ntilization of coal fines are mentioned, and the results of flotation tests on coal fines from three important coal seams in New South Wales are presented.INTRODUCTIONEconomic utilization of fine coal is an important problem in the Australian coal industry, particularly as the proportion of fines mined is increasing with progressive mechanization.While the use of uncleaned coal fines may be economic, it may be preferable to beneficiate them, but the most economic process must be selected.For beneficiating coal finer than about 28 mesh, froth flotation can be applied, but mining engineers should avoid practices that may be detrimental to flotation. Such practices include the indiscriminate use of water, particularly that containing a wetting' agent, for dust suppression. In addition, clay stemming in wet conditions may produce slimes which could adsorb on coal surfaces, while the use of oils and greases as well as the application of stone dust and chlorides in roadway consolidation may influence adversely fine coal beneficiation.This paper deals with the application of flotation to samples of fine coal from the Bulli, Greta, and Victoria Tunnel seams. In addition a discussion is given of the mineralogical constitution, size analysis, and degree of liberation of ash constituents of the various samples.COAL SAMPLESRepresentative samples of coal from the Bulli, Greta, and Victoria Tunnel seams were obtained for testing.

Jan 1, 1961

By Caithness SJ, Heape JMT

Following the discovery by CRA of gold at Mt Kare, and the subsequent 1988-90 gold rush, mechanised mining of the alluvial resource is now being carried by a company jointly owned by CRA (51%) and landowners of the area (49%). Mining is currently being carried out using small gravity processing plants fed by hydraulic excavators. Use of hydraulic mining techniques will be limited to over- coming difficulties related to the high clay content of the material and the soft nature of the bedrock. Current resource estimates suggest that the alluvials will have a mining life of three to four years. During this time, exploration of the hydrothermal gold mineralisation at Mt Kare will be carried out by a wholly-owned company of CRA. It is hoped that this will lead to establishment of an economic primary gold resource.

Jan 1, 1991

By Brian Gar Wingfield

"The introduction of the QuarryMan laser profile system in 1987, along with the development of the corresponding 3-D software, gave a qualified operator pertinent information about dimensions of quarry highwalls, pattern and hole loading design, stockpile profiles, etc . . . Attributes helpful for this endeavor included surveying, computer, and blasting knowledge. Since not all operators had theseskills, a simpler model, the QuarryAce, was designed to look a t highwall dimensions in 2-D view . Al though less sophisticated than the QuarryMan instrument and its software, it is simpler to instruct in its use and has the ability to determine burdens at different depth levels . An in-house user f r i e n d l y computer program was designed to utilize QuarryAce depth vs. burden data . This program was created to enable laser and computer novices to generate information useful to the everyday blaster."

Jan 1, 1992

Before presenting this address I desire to express my appreciation of the honour which has been conferred on me by my election as iPresident of The Australasian Institute of Mining and Metallurgy. At this stage it might not be out of place to recall that Broken Hill was the birthplace of The Australasian Institute of Mining and Metallurgy, originally formed as the Australasian Institute of Mining Engineers in 1893.In selecting for my address the topic of "The Broken Hill Mining Industry and its Contribution to the Economy of Australia" I realise it is impossible to cover fully every aspect of the nation's economy which owes all or part of its origin to the Broken Hill field. Nevertheless, I feel that some attempt should be made to give credit to the Broken Hill mining industry for its part in the progress which Australia has made over the past seventy years.. If we care to reflect for a moment it soon becomes apparent that, not only is the Broken Hill mining industry an important producer of base metals for domestic and overseas consumption, but its profits have provided the means whereby many of Australia's leading secondary industries have been established or built up. Examples which come to mind are the founding of the iron and steel industry by the Broken Hill Proprietary Company; the establishment of plants at Port Pirie in South Australia, and at Risdon in Tasmania, for the production of metallic lead and zinc; and also at Port Kembla for the smelting of copper ores. From profits derived from operations at Broken Hill, capital has also been provided to assist other new essential...

Jan 1, 1956

By Jones S. C

A specific arc can be cut in hard rock formations using a specially designed multistep piloI bit, variable sized drift joint and long heavy control rod as a stabilizer rather than the Vaughan Thompson "Lifting" arc cuttingequipment. The rate of deflection can be controlled after an initial determination of behaviour in any particular rock type.

Jan 1, 1966