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By H. W. Ahrenholz

Seven weeks of 1971 were devoted to a nationwide coal walkout resulting in lost production of some 70 million tons and leaving 1971 coal production at about 550 million tons. Compounding the problem, consumption of coal in 1971 by electric utilities rose by about 5% to 336 million tons. In the mean- time, numerous contracts were awarded for coal R&D including $24.8 million given by the Office of Coal Research to Bituminous Coal Research for the construction of a coal-to-gas pilot plant using the BIGAS process. Exports declined mainly due to Japan's decrease in steel production and to that country's increase in coal imports from Canada and Australia. The advances in equipment design and mining procedures made 1971 a noteworthy year. Introduction of the variable pitch I dipper, the trend toward wheeled vehicles, the greater use of scrapers in reclamation and battery-operated vehicles and oscil-mining, and the increased activity in the areas of ventilation and dust control were given widespread approval. There were also strides made in computerization, longwall mining, roof bolting, rock dusting, mine haulage and methane detection.

Jan 2, 1972

By E. Daniel Baker

"The term ""oxide disseminated gold deposits"" refers to near surface, gold-bearing veins, faults, and shear zones that typically contain appreciable amounts of oxidized ore or gossanous material, resulting from oxidation of sulphides.The concept of oxide gold deposits underwent a dramatic change after the discovery of the Carlin gold mine in north-central Nevada in the early 1960's. Now the term implies large tonnage, low-grade bulk minable deposits that are processed by milling and/or heap leach methods.Oxide gold deposits may now be classified into two types: (1) primacy ores derived directly from the effects of hydrothermal alteration on host rocks, and (2) secondary oxide ores derived from the supergene oxidizing effects of circulating post-mineral meteoric waters on gold-bearing sulphides. Each type of deposit has unique diagnostic mineralogic and metallurgical characteristics that must be addressed to achieve successful exploration strategies and viable metallurgical exploitation.The author would like to thank the management of Newmont Metallurgical Services and Newmont Mining Company for allowing presentation of this paper. Thanks are due Sevkett Acar, Donald M. Hausen, Jerry R. Odekirk, and D. Erik Spiller for their critical review of the manuscript. Also, thanks are extended to all those cited and uncited whose hard work and dedication have led to the discovery and exploitation of near-surface oxide gold deposits. Our knowledge would be greatly limited without the dedication and research of many others."

Jan 1, 1997

By Philip W. Holland

The Bureau of Mines has developed a trace helium analyzer for deter-mining helium-4 in the parts-per-billion range. The instrument is used for analyzing pure gases, laboratory-prepared standards, and atmospher-ic samples. Accuracy at the 95-pct confidence level in the 50-to 20,000-ppb range is within ±2 ppb or ±0.4 pct, whichever is greater. The minimum detectable helium-4 concentration is calculated to be 5 ppb. The analyzer consists of a modified helium leak-detector mass spec-trometer, a laboratory-built sample inlet system, and a liquid-nitrogen-cooled charcoal trap. A programmable integrator and event-control module make automatic operation possible. The portability of the analyzer allows it to be used in the field.

Jan 1, 1984

By Elford H. S, Hughes J. F

The object of this paper is to bring before Members of the lnstitute the very important and much discussed question of scientifically prospecting for ores, oil, coal, etc.The paper is divided into three sections:SECTION l - Description of Geophysical Prospecting methods.(1) Sound-Vibration.(2) Magnetic.(3) Gravitometric.(4) Electrical.(a) Equipotential.(b) Electro-magnetic.(c) Schlumberger.(d) General.SECTION II - General discussion of Cicophysical Prospecting.SECTION III - Appendices.(1) Systematic summary of methods of survey.(2) Table of electrical conductivities.(3) Bibliography.SECTION I - DESCRIPTION O:F GEOPHYSICAL PROSPECTING METHODS.(1) SOUND-VIBRATION.THE transmission of sound waves or vibrations underground will depend on at least three factors: (a) Type of Rock. - Hard, dense rocks wiII transmit sound waves much more quickly than softer, more porous rocks. In the former the speed may be eight times that of the latter.(2) Uniformity of Rock. - Any variation in the texture, hardness, etc, wiII have an effect on and direction of transmission of the waves.

Jan 1, 1927

By W. A. Backofen, D. Lee, F. S. Jabara

THE empirical character of plasticity analysis insures a continuing need for measurements of the yield surfaces of anisotropic materials. Recently, Wheeler and Ireland (W-I) proposed that an octahedral yield locus could be constructed on the basis of six Knoop hardness indentations. Such simplicity would have obvious appeal, if it led to consistently dependable results. In other recent work, a much more straightforward (and more tedious) method of measurement was used to establish all quadrants of the plane-stress yield loci for two substantially anisotropic titanium alloys.2,3 The same materials have since been reex-amined by the W-I method with results being reported here. A full description of the stress state under a Knoop indentor would be complex. In principle, however, this can be avoided in relating the hardness number to a plane-stress yield locus, by the expedient of superimposing the appropriate hydrostatic component on that state of stress. Six possible orientations of in-dentor on orthogonal (symmetry) planes, along (principal) coordinate directions, are illustrated in Fig. 1(0). Pictured in Fig. l(b) are normal-stress components nominally associated with indentation n: o2(H), directly proportional to the Khn in this case, together with By overlaying a hydrostatic tension, ah, that in general is equal to the stress state around the indentation is reduced to one of plane stress in the x-y plane for which the stress ratio is a The key step in the W-I yield-locus construction is to represent the Khn for any indentor orientation as a vector quantity on the octahedral plane. In the plotting, the vector is given as deviatoric stress components along the principal axes in the ratio , where represents the direction of the minor (width) diagonal and 1 that of the major (length) diagonal. There is no attempt by W-I to justify the 7/1, although it might be supposed that the value originates in the usual ratio of major to minor diagonals in a Knoop indentation of about 7/1. If that were its origin, the link to the deviatoric stress ratio would presumably be made by first taking 7/1 and then turning to the Levy-Mises equation for isotropic material: Interpreted in this way, the W-1 approach seems arbitrary and even contradictory. Yet it would still be favored by two circumstances: the deformation under a Knoop indentor approaches plane strain: when dcw/del =a; and the shape of the locus where plane strain is represented is not overly sensitive either to the exact value of dc,/dcl or to the degree of anisotropy, within a rather wide range of both variables. The second point is illustrated below, after a few additional comments on applying hardness

Jan 1, 1968

By Persifor Frazer

IN his “Final Report," Vol. II, part second, p. 763, Prof. Rogers sums up the metalliferous veins of the mesozoic sandstone by remarking that these are not associated with dykes or trap-rock, but are independent metalliferous injections. But singularly enough, in enumerating the different kinds of ores, no mention is made of

Jan 1, 1877

By Ron Ketterling

We will discuss electronic and paper record keeping, what works and what doesn’t. We’ll review record keeping in light of those five sub-committees: Audit, Awards, Constitution, Ethics and Planning. You’ll come away with concrete steps you can use to improve your record keeping processes

Feb 1, 2020

By R Jaine, D Strang, M Fowler

"This paper presents a case study demonstrating active geotechnical pit slope management at the now completed Carina Iron Ore Project operated by Mineral Resources Ltd (MRL). The site is located 105 km north-east of Southern Cross, Western Australia. The paper is primarily focused on the slope stability failure modes and the remedial measures employed to maintain mining.Between a quarter and a third of the excavated slopes were impacted by some form of instability that was beyond expectations of the intended slope design criteria and common practice. Ongoing mining was supported by intensive geotechnical pit slope management including close cooperation between geotechnical, mine planning and operations staff to achieve timely and practical mining solutions.Mining encountered varied slope failure mechanisms which required a combination of remedial solutions comprising: horizontal depressurisation holes, deferral of excavation, unloading, buttressing and catch berms.The root cause of the challenging slope performance was a mismatch between the predicted and encountered geotechnical model, resulting from a failure to recognise the critical mechanisms that control slope stability.Despite the extensive zones of instabilities at completion of mining, full ore recovery was achieved without major delays and in a controlled and safe manner.Citation:Fowler, M, Strang, D and Jaine, R, 2016. Adapting to Geotechnical Change - a Case Study of the Carina Open Pit Mine, in Proceedings Ninth AusIMM Open Pit Operators' Conference 2016, pp 150–161 (The Australasian Institute of Mining and Metallurgy: Melbourne)."

Nov 15, 2016

By LeRoy D. Loy

The coal mining industry must be able to compete with alternate sources of fuel for the utility and industrial customers. If the industry is unable to control transportation costs, either due to government interference, or for other reasons, then mining costs must be kept down. Australia, South Africa, Canada, (and later Colombia) will take larger shares of the export market if mining costs are not kept competitive. The government's environmental regulations must be met without incremental increases in mining costs. Entrepreneurial instincts must be retained by the industry to provide for their investment in the future. What are the Problems with Existing Research? Government funding for coal mining research has been reduced or virtually eliminated. BCR (Bituminous Coal Research) is now a membership- supported organization, but its primary focus has been on health and safety-oriented research. BCR, however, is now attempting to widen its scope and conduct other types of research. There are almost no funds in EPRI's (Electric Power Research Institute) program for coal mining research. Large mining companies do some research for their own purposes and needs, but this is proprietary and therefore results are not shared with the remainder of the industry. The mining industry as a unit is not undertaking productivity (systems) oriented research in any common or cohesive manner.

Jan 1, 1983

By J. J. DeMull, B. A. Boster

Amax's Sleeper mine uses conventional cyanidation milling and heap leaching techniques to produce gold. Since milling operations commenced in March 1986, average ore processing rates have improved from the design rate of 455 t/d (500 stpd) to more than 720 t/d (795 stpd). Heap leaching was added to the process facilities in September 1986 at a design rate of 1.5 kt/d (1650 stpd) and current heap leaching rates exceed 2.7 kt/d (2950 stpd). Presented are descriptions of the Sleeper processing facilities with emphasis on the crushing and grinding circuits, a review of the selection of crushing and grinding equipment, and a summary of operating performance during the first 16 months of operations.

Jan 1, 1990

By L. Shevenell

Nevada now has, or will have, 35 pit lakes resulting from open-pit mining below the water table. State regulators are requiring that the ultimate pit lake water quality be predicted as part of the permit application process. Water balances/pit lake filling rates must be esti¬mated in support of the geochemical modeling. In Nevada, analytical and numerical methods have been employed for the study of pit lakes. In the current work, analytical solutions are investigated for one pit lake, the Getchell south pit lake, which previously filled be¬tween 1968 and 1982 during a hiatus in mining. Water levels vs. time are available for this lake and these data have been fitted with a hyperbolic curve. This water-level-vs.-time curve was used in simple water-balance computations to find the net inflow rates by forcing computed water levels and volumes to match those of the known water levels and volumes through time. The model described here provides realistic volume fluxes into and out of the lake on a monthly basis as the pit lake filled.

Jan 1, 2000

By Persifor Frazer

In his " Final Report," Vol. 11, part second, p. 763, Prof. Rogers sums up the metalliferous veins of the mesozoic sandstone by remarking that these are not associated with dykes or trap-rock, but are independent metalliferous injections. But singularly enough, in enumerating the different kinds of ores, no mention is made of

By R. S. Wagner, W. C. Ellis

A new mechanism of crystal growth involving oapor, liquid, crnd solid phases explains many observations of the effect of implurities in crystal growth from the vapor. The role of the impuuitq is to form a liquid Solution with the crystalline tnalerial to be grown from the vapor. Since the solution is n prefevred site for deposition firorti the uapor, the liquid becorrles supersaturated. Crystal growth occurs by precipitatzon from the supersaturated liquid crt tlie solid-liquid zntevfnce. A crystalline defect, such as a screw dislocation, is not essetztial for VLS (vapor -liquid-solid) growth. The concept of the VLS mechanism is discussed in detail with reference to tire controlled growth of silicon crystals using gold, platinum, palladium, nickel, silver, or copper as an implurity agent. RECENTLY a short communication' described a new concept of crystal growth from the vapor, the VLS mechanism. In this paper we present a detailed description of the process and its application to the growth of silicon crystals and we discuss its relevance to existing concepts of .'whisker" crystal growth. Crystal growth from the vapor is usually explained by a theory proposed by Frank2 and developed in detail by Burton, Cabrera, and Frank.3 In this theory a screw dislocation terminating at the growth surface provides a self-perpetuating step. Accommodation of atoms at the step is energetically favorable, and is possible of much lower supersatu-ration than required for two-dimensional nucleation. Crystals of a unique form resulting from aniso-tropic growth from the vapor are "whisker" or filamentary ones. Such crystals have a lengthwise dimension orders of magnitude larger than those of the cross section. For most filamentary crystals both the fast-growth direction and directions of lateral growth have small Miller indices. The special growth form for a whisker crystal implies that the tip surface of the crystal must be a preferred growth site. sears4 proposed that, according to the Frank theory. a whisker contains a screw dislocation emergent at the growing tip. Such an axial defect provides a preferred growth site and accounts for unidirectional growth. The hypothesis was extended by Price. Vermilyea. and Webb," still implying the presence of a dislocation at the whisker tip. They postulated that impurities arriving at the fast-growing tip face become buried while those arriving on the surface of slow-growing lateral faces accumulate and thereby hinder growth. These considerations led to a whisker morphology. There is increasing evidence that most whisker crystals grown from the vapor are dislocation-free. Webb and his coworkers6 searched for an Eshelby twist7 in zinc? cadmium, iron. copper, silver, and palladium whisker crystals. They found unequivocal evidence for an axial screw dislocation in only one element, palladium. However, not every palladium crystal examined contained a dislocation. Observations with the electron microscope have failed to show dislocations in whisker crystals of zinc, silicon.9 and one morphology of AlN.10 Since many whiskers are completely free of dislocations, an axial dislocation does not appear to be required for whisker growth of many substances. A significant advance in understanding whisker growth has been a recognition of the need for impurities. This requirement has been clearly demonstrated for copper,11 iron,13 and silicon9-1 whiskers. For silicon, detailed studies proved conclusively that certain impurities, for example, nickel or gold, are essential. Another pertinent phenomenon which has received little attention is the presence of a liquid layer or droplets on the surface of some crystals growing from the vapor. Crystals in which this has been observed include p-toluidine,14 MoO3,15 ferrites,16 and silicon carbide.'" The liquid layers or globules were considered to be metastable phases, molecular complexes, or intermediate polymers originating from condensation of the vapor phase. The possibility has been suggested that the halide being reduced is condensed at the tip18 or adsorbed on the surface11 of a growing metal whisker, for example copper. The literature on whiskers discloses illustrations of rounded terminations at the tips. These appear. for example, on crystals of A12O3,19,20 sic,21 and BeO.22 For BeO, Edwards and Happel suggested that during growth of the whisker the rounded termination consisted of molten beryllium enclosed in a solid shell of BeO. A recent paper9 on the growth of silicon whiskers contains many observations pertinent to an understanding of the mechanisnl of whisker growth. These observations are summarized as follows. 1) Silicon whiskers are dislocation-free. 2) Certain impurities are essential for whisker growth. Without such impurities the silicon deposit is in the form of a film or consists of discrete polyhedral crystals.

Jan 1, 1965

By A. M. Gaudin

The flotation process has been applied extensively in the mineral and chemical fields. This paper reveals results obtained by an exploration of an application to the biological field. In many ways this study was indeed an exploration since so many factors are different. In the mineral field, the particles, both those floated and those not floated, cover a wide range of sizes and shapes; in the biological field, the particles of one population are primarily of one or two sizes and one or two shapes. This identity in size and in shape gives biological systems the advantage of homogeneity. In the mineral field the particles may be as coarse as a millimeter; in the biological field the size may be a micron, or less. In the mineral field the particles may have a gravity several times that of water so that their apparent gravity is quite substantial. Microorganisms, on the other hand, may have a gravity so near that of the liquor that their settling velocity in the liquor is vanishingly small. These two facts conspire to make bubble-particle encounter in the pulp-body less likely. Finally, microorganisms are living, reproducing, and dying-all of which does not help the experimenter get a balance of materials. The analytical problems, too, are extraordinarily difficult, for the organisms can contain only elements that occur in their environment, although at a different level of concentration. The chemical composition of the surface of microorganisms is readily altered. In spite of these areas of difficulty, microorganisms can be floated to leave practically water-clear tailing, they can be floated from each other and, in fact, the same organism can be fractionated into a float that differs from the sink. SIZES AND SHAPES OF ORGANISMS Most ore pulps are described with reference to the percentage of the pulp that is fine enough to pass a 200-mesh sieve. Thus a copper-ore pulp may be 80% -200 mesh. Since 200 mesh equals 74 µ, a 2000-mesh particle would be 7.4 µ in diameter, and a 20,000-mesh particle would be 0.74 µ. The microorganisms with which this work is concerned are of the order of magnitude of 20,000 mesh. We have worked with Escherichia coli, the colon bacillus, Bacillus cereus, Bacillus subtilis, Bacillus megaterium, and Serratia marcescens. In some pioneer work, Dognonl,2 reported the use

Jan 1, 1962

By Phillip Mackey, Elmira Moosavi-Khoonsari

L'industrie du cuivre traverse une période passionnante, marquée par une forte demande, de bons prix et l'ouverture de nouvelles grandes installations. L'année 2022 a battu des records de production de cuivre, ce qui laisse entrevoir un potentiel de croissance supplémentaire. De grands projets sont en cours, comme la technologie Double Flash à Manyar, en Indonésie, qui peut produire plus de 500 000 tonnes de cuivre par an. À Munda, en Inde, on a construit la plus grande usine de cuivre du monde, qui produit plus de 1 000 000 tonnes de cuivre par an en combinant deux phases. De plus, l’installation de cellules de flottation de dernière génération au Mexique, au Chili et dans d'autres pays témoignent de la volonté de l'entreprise d'utiliser les technologies les plus récentes [1]. L'importance du cuivre dans la transition énergétique est évidente, l'accent étant mis à la fois sur la croissance et sur la protection de l'environnement. Cela se traduit par le développement d'usines de premier ordre dédiées aux pratiques durables.

May 2, 2024

By V. Feldman, I. Holl, J. Zampini

"The Renard Mine, 100% owned by Stornoway Diamonds, is located approximately 250 km north of the Cree community of Mistissini and 350 km north of Chibougamau in the James Bay region of north-central Québec. The project benefits from a large and growing resource, good mining conditions, strong social acceptance, a modest environmental footprint, and the development of direct-to-mine road infrastructure. Construction began on July 10, 2014; following the completion of a 946 million CAD project financing transaction. Now completed, the mine is the first diamond mine in Québec, and one of only six in Canada, employing approximately 500 people. First ore was delivered to the plant approximately 5 months ahead of schedule on July 15, 2016. Commercial production was declared on January 1, 2017. In general, the project ramp up has been characteristic of a type 1 McNulty curve. One of the challenges during production ramp-up was a redesign of processed kimberlite dewatering (replacing the dewatering centrifuge with two stages of hydrocyclones and a dewatering screen). A processing opportunity captured by Stornoway was the design and installation of an ore sorting facility which rejected free waste rock from the valuable host rock; kimberlite. Through tackling both challenges and opportunities, Stornoway has realised and is now exceeding their original design tonnage.PROJECT DESCRIPTION Stornoway Diamond Corporation (Stornoway) was established in 2003 resulting from to a plan of arrangement between Northern Empire Minerals Ltd. and Stornoway Ventures. In 2011, Stornoway acquired 100% interest of the Renard Mine. The construction of the Renard Mine began in 2014 and achieved full production in 2017 [1, 2]."

Jan 1, 2019

By G. S. Dobby

Particle collection is considered to occur by particle collision with the bubble followed by the particle sliding over the bubble during which attachment may occur. Collision is quantified by a collision efficiency, EC. The existing model for EC is extended by including particle inertia. Attachment is quantified by an attachment efficiency, EA calculated as the fraction of particles which reside on the bubble for a time greater than the induction time. These calculations use recent data on the liquid velocity distribution over the upper half of rigid spheres. Collection efficiency, EK is given by EK = EC ? EA. Detachment is not considered. The mode is examined and shown to agree with much experimental data. For example the maximum observed in recovery vs particle size (d) can be explained as E increases with increasing d , while EA decreases. The decrease in selectivity at fine sizes is in accord with the model result that for dp < 5µm, EA ? 100% (i.e. EK ? EC) almost regardless of induction time. A decrease in bubble size does increase EK but does not improve selectivity. A high particle density (> 5g/cm3) is shown to cause a sharp peak in recovery vs size and a decreased maximum size of floatability. Finally, the possible effects of bubble and particle concentration are explored.

Jan 1, 1985

The Kanowna Belle deposit was discovered in 1990 following encouraging assays from soil sampling and RAB drilling. At the end of September 1993, diamond drilling had been completed to a vertical depth of 1,000 metres and a resource of 22 million tonnes grading 5.73 grams of gold per tonne containing a million ounces of gold had been defined. The deposit remains open at depth. Pre-production mining for the open pit began in November 1992, construction of the oxide treatment plant began in January 1993 and the first gold was poured in September 1993. Sulphide ore roasting commenced in December 1994 and the underground mine development commenced in July 1995. The Kanowna Belle project is owned by the Golden Valley Joint Venture (GVJV), an unincorporated joint venture with equal shareholdings between North Gold (W.A.) Ltd and Delta Gold N.L. North Gold are the managers of the development and operations and Delta Gold are the managers of exploration throughout the GVJV tenements.

Jan 1, 1990

By D. Tao, B. K. Parekh

Fine coal particles are difficult to separate effectively from liquids or other solids. Ultrasonic energy may be used to enhance the efficiency of the conventional fine-particle separation processes widely used in the coal and mineral industries. Flotation, settling and dewatering tests were conducted using several fine coal samples to study the effects of ultrasonic treatment on these processes. Process variables such as particle size, ultrasonic treatment time and solids concentration were investigated for their impacts on ultrasonic treatment effectiveness. The results obtained from this study showed that ultrasonic treatment is an effective approach for enhancing solid/solid separation in flotation and solid/liquid separation in sedimentation and dewatering of fine coal. SEM microphotographs demonstrate that ultrasonics cleaned particle surfaces, which is, in part, responsible for the observed improvement in fine coal separation processes.

Jan 1, 2000

By C. Alexander

Stillwater Mining Company is developing a second underground palladium and platinum mine approximately 21 km (13 miles) west of their existing Nye operation in south central Montana. A 5650 meter (18,550-foot) tunnel is required to gain access to the ore bearing horizon (J-M Reef). Access and primary mine development can be accelerated through the use of two 4.6 meter (15-foot) diameter tunnel boring machines (TBM). One TBM was purchased new while the other was purchased used. Machine specifications, site support facilities, portal/launch chamber construction, TBM assembly, startup and operation are discussed in this paper.

Jan 1, 1999