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By Ta M. Li, John D. Wiebmer

Record high prices, burgeoning exploration programs, mine-mill openings, and plant expansions have all characterized a dramatic: resurgence of the US uranium industry in recent years. But while the bull is leading the way on the production side of the nuclear fuel cycle, there is reason for caution from the end-users' viewpoint. How fast will electrical demand grow in the years to come, and what portion of that will nuclear generators supply? How do utilities play their cards when the government holds two of the largest jokers in the deck-a policy on spent fuel reprocessing and a timetable for the fast breeder reactor? Is there a shortfall in domestic uranium supplies on the horizon?

Jan 10, 1978

Jan 1, 1968

By Teja Reddy, Narasimha Mangadoddy, Mandakini Padhi

"In mineral comminution circuits, the feed to hydrocyclone consists of a heterogeneous mixture having varied degrees of liberation and sizes leading to the multi-component particle system. The presence of multicomponent particles exhibits a significant change in the classification performance parameters. In this work, a numerical study is conducted with an artificial mixture of magnetite and silica of different proportions having similar particle size distribution to understand the multicomponent interaction in a laboratory scale hydrocyclone. The heterogeneous feed is injected tangentially would attain different settling rates under the influence of centrifugal, drag and turbulent dispersion forces. In this work, Large Eddy Simulation (LES) is used to resolve the continuous phase turbulence. Modified Algebraic Slip Mixture (ASM) model using the corrected Newtonian rheology of fines to simulate multi-density and multi-size particles of the mixture in a hydrocyclone. The influence of the multi-component particles on classification performance is extracted from the simulation in terms of the performance curve, i.e. recovery to underflow, volume fraction distribution and the key forces acting on each particle in the mixture. An interaction was observed between different components during the classification process, featuring accumulation of heavier particle at wall-side pushing the lighter particles into the inner locus of zero vertical velocity (LZVV) zone. The comparison of separation factors of different size particles presented the higher probability of the magnetite of same size reporting to wall region and hence to underflow. Hence, an increased component cut-size with the increased magnetite proportion, particularly a profound effect on lighter density component’s cut-size was observed. INTRODUCTION The multicomponent existence is found in naturally occurring ores, affecting the pure metal extraction, nonetheless also affects the comminution and classification processes. Among many another classifier, hydrocyclone is a vital equipment used vastly in many industries. The main advantages over other classifiers are a static body, low operating cost and maintenance, high throughput, low floor space requirement etc. A typical hydrocyclone consists of a cylindrical section with a central tube connected to a conical section with a discharge tube. The fluid is injected tangentially into hydrocyclone causes swirling and thus generates centrifugal force within the device. The multiphase interaction inside the hydrocyclone is extremely complex and mostly explained by theories based on hypothesis. In past years, many theoretical models were proposed like a balanced orbital model (Criner, 1950), the residence time model (Reitema, 1961) etc. Though these models give an estimation of the cut-size and other performance parameters, it cannot predict the accurate performance of the actual state of operation. Among these models, the balanced orbital theory is the most adapted concept, based on the force balances of the particle in the dual vortex flow of hydrocyclone. The finer particle is subjected to the inward drag force, generated from the outer vortex flow to the air core, and drags the particle towards the overflow. The larger particle with the higher mass have enhanced centrifugal force and falls into primary vortex near wall reporting to the underflow. Generally, the forces acting on the particle include the drag force, centrifugal force, pressure gradient force, added mass force, Saffman lift force, Magnus force and basset force (Kraipech, 2005). The major forces like a drag, centrifugal, pressure gradient are the function of the particle properties like the size and the density. Hence, the existence of the multi-size and the multi-density particle will affect the separation phenomenon, with the varied forces acting on it. The understanding of the multicomponent classification effect using ores has been only explored in few studi"

Jan 1, 2018

By J. Dubinski

Passive tomographic imaging is a technique that can be used for assessing seismic hazard in mines with high seismic activity induced by mining. The basic idea behind such an interpretation is the assumption that there is a relationship between high values of seismic velocity and high values of stresses in the rock mass. This relationship was confirmed both in laboratory an in situ measurements and constitutes the basis for rock-burst and seismic hazard evaluation. In the paper seismic tomographic images of seismic P wave velocity and seismic P wave velocity gradient have been presented to determine rock-burst hazard and locate high seismic activity zones in the area of coal panel 306 in Zabrze Bielszowice mine. The zones of high values of P-wave seismic velocity gradient have been found to correlate with the distribution of high energetic seismic events. Passive tomographic images were obtained using modern bent ray tracing tomography algorithm with regularization. Recent study give rise to observation that not only high values of P-wave seismic velocity is important in seismic hazard assessment as many strong seismic events are located in the areas of high values of velocity gradient. This recent observation permits to increase quality of passive tomographic imaging for detection of seismogenic zones and is presented in the paper. The advantage of passive tomography comparing to active tomography is that sources of seismic waves are generated by rock mass itself and costly controlled explosions are not necessary. Another practical limitation of active tomography is the size of study area which usually do not exceed 200 m by 200 m. This restriction does not appear in passive tomography where area of study is usually 2000 m by 2000 m and the tomographic images delineate velocity structure in locations where mining induced seismicity take place. Passive tomography method utilized in analysis of rock mass state in underground mines encounter some difficulties concerned with the numerical stability of optimization algorithms. In the presented approach to passive tomography problem numerical stability is obtained by special regularization method and by application of very stable numerical seismic ray-tracing algorithm.

Aug 1, 2013

By A. W. Jacob

THE shatter cut, or burn cut as it is often called, is one in which the centre of the round is almost reamed out by drilling holes so close together that the blasting of a few holes shatters the rock embraced by all of them. The idea of shattering the centre of a face by shooting holes drilled parallel to one another is not new. Some miners have used this method for years past, when drilling quartz or a face near timber. But, they followed the age-old practice of first blasting the cut, then the square-up. It was not thought possible to shoot both together. In the case of machine men, the two largest contributors to silicosis are dust from drilling and dust from blasting. It follows, then, that material reduction of exposure to either constitutes an important step in lessening the incidence o silicosis. It was? the hope of being able to do away with the necessity of the men having to return early to a face, through dust concentrations of 60,000 to 80,000 particles per cubic centimeter, that aroused interest "in the shatter cut at McIntyre. Efforts to this end were successful. Now, with this kind of cut, all holes of a round are shot simultaneously.

Jan 1, 1942

By G. N. Jadhav

In India, bauxite deposits are concentrated in Central India, Western Ghats and Eastern Ghats. Bauxites from various regions in Gujarat were identified during the present investigations of geochemical mapping. Different types of Bauxites samples were collected from Kachchh, Jamnagar, Porbunder, Junagarh, Bhavnagar and Amreli areas of Gujarat state and were studied in detail for their geochemical signatures to plot the data on Geochemical map. Raw bauxites were characterized by using powder XRD, XRF, ICP and optical microscopy techniques (with the help of Model microscope having both transmitted and reflected light setups) and were later examined to grade their quality. Most of the bauxites from Kachchh region were of high-grade (gibbsitic) type; while those of Sourashtra region were of low-grade (lateritic / calcitic) types. Most of these bauxites were either of ferruginous/lateritic or of calcareous/calcitic types. Based on the mineralogical composition, such as gibbsite, hematite and/or goethite, Kaolinite and calcite minerals present in particular bauxites, the deposits were graded. Finally, the Geochemical mapping of Bauxites for Gujarat region was prepared and discussed.

Sep 1, 2012

By Rose L. Ballard

This chapter summarizes data on crude nonfuel mineral production for the United States, its island possessions, and the Commonwealth of Puerto Rico. Included also are tables that show the principal nonfuel mineral commodities exported from and imported into the United States, and that compare world and U.S. mineral production. The detailed data from which these tables were derived are contained in the individual commodity chapters of volume I and in the State chapters of volume II of this edition of the Minerals Yearbook. Although crude mineral production may be measured at any of several stages of extraction and processing, the stage of measurement used in this chapter is what is normally termed "mine output." It usually refers to minerals or ores in the form in which they are first extracted from the ground, but customarily includes the output from auxiliary processing at or near the mines.

Jan 1, 1982

The morphological changes that gold undergoes during transport in gravel-bed rivers are a function of transport distance in particular, as well as bedload material, river gradient and velocity, and bed roughness. Gold size, shape and outline are modified by abrasion, flattening, folding and breakage during transport. The resultant morphological characteristics can be used to predict source types, source location and transport distance, as well as the origin and dispersal patterns of gold in ancient placers where the transport history is unknown.

Jan 1, 1998

By N. B. Aughenbaugh

Subsidence due to abandoned coal mines has received copious attention recently. This is a result of many factors such as the enactment of new mining laws and the effect subsidence has on land use over the mines. Prediction of subsidence features and the time aspects over supercritical extraction (i.e., longwall and high extraction ratio pillaring) is relatively accurate. However, predicting when subsidence will occur and the surface features' size and shape above subcritical extraction of room and pillar mining is not yet possible. This paper will discuss the factors that influence the time aspects of subsidence in room and pillar mining.

Jan 1, 1983

By J. W. Meckenstock

Evidence of the fact that the beneficiation of sand and gravel is now going on is readily observed by visiting various and and gravel plants almost throughout the U.S.A. of necessity this beneficiation process is concentrated more in certain areas than in others, and it is steadily increasing. Therefore, it can be said that beneficiation is now one of the processes inn the manufacturing of sand and gravel, It started some ten to twelve, years ago when the need for beneficiation made itself known, and when the manufacturers of sand and gravel producing machinery began to make equipment available to the industry.

Jan 1, 1958

By A. Lyndon

Vertical and lateral load tests were carried out on two 13 m deep bored cast-in-place instrumented piles, socketed into weathered sandstone. The first pile, 1200 mm in diameter, was loaded vertically to a maximum of 16000 kN and then loaded to failure under lateral load (1900 kN). The second pile, 1500 mm in diameter, was tested under lateral load up to a maximum of 2400 kN. It was found that the deflections of the 1200 mm pile were more than twice those of the 1500 mm pile under similar loads. The soils on the site are not easily tested in the laboratory, or by conventional insitu site investigation techniques, parameters needed in design can only be reliably obtained from pile test results. In this report shear moduli are back analysed from the vertical load test and the two lateral load tests. For these similarly installed piles very different design parameters were determined from the lateral load tests, the only known major difference between the piles being that the 1200 mm pile was loaded vertically before it was loaded laterally. Changes in G values needed to match performance under vertical load if applicable to lateral loading could have accounted for a significant amount of the difference.

Jan 1, 1989

By Richard S. McCaffery, Morrison B. Yung

While assaying some copper carbonate ore from the Frazer claims, Similakameen, B. C., I noticed that on parting the gold button a deep orange solution was formed. The button gave off pink bands in the nitric acid, which became deep orange at a short distance from it; and as it traveled over the surface of the porcelain dish, it left a deep orange track behind. As the button brightened in the cupel, it appeared to have a bronze color; but I have since found that when amarillium is in large excess of the gold, the button is a very dark gray. The button parted easily. To the orange solution I added a salt (NaCl) solution, shook in a silver testbottle, and filtered. With H2S I obtained a precipitate, which I supposed due to platinum. However, on further tests, it did

Jan 1, 1903

By Richard H. Siller, Rex B. McLellan

A model for interstitial solid solutions has been considered in which a repulsive Potential exists between interstitial atoms in the solvent lattice. It has been shown that this model is consistent with the thermodynamic Properties of certain interstitial solid solutions. The model is then applied to the calculation of the variation of the diffusivity of carbon in au-tenite with composition. Although the energy levels at the saddle point, and thus the absolute values of dif-fusivity, cannot be calculated, it is shown that by taking the repulsive interactions between the diffusing atoms into account the functional form of the dependence of diffusivity on solute concentration can be derived. ThE composition dependence of the diffusivity, D, of carbon in austenite at a given temperature is well-known.'-3 smith3 tried to reconcile the observed composition dependence of D at 1000°C with the previously observed4 composition dependence of carbon activity using equations for D derived by arken5 and Fisher, Hollomon, and Turnbull,6 but was unsuccessful. In this paper we shall modify the approach of Fisher et al. by considering the "blocking" model7 for interstitial solid solutions, based on concept due to Speiser and Spretnak,' in which a repulsive potential exists between interstitial solute atoms in the solvent lattice, causing a certain number of interstitial sites to be "blocked" from occupancy by further solute atoms. We shall thus be able to describe the intimate relationship between the composition dependence of carbon diffusivity, a kinetic phenomenon, and the composition dependence of carbon activity in austenite. THEORY Consider for convenience one-dimensional interstitial diffusion in an fcc lattice in the [loo] direction. Fig. 1. Assume that solute atoms occupy octahedral sites only.7,9'10 These octahedral sites are located on {lOO} planes a/2Å apart. A solute atom, A, occupying an octahedral site on a {100 } plane denoted by 2, has twelve nearest-neighbor octahedral sites: four on plane 1, four on plane 2, and four on plane 3. Diffusion occurs when there is a net flux of solute atoms, through an imaginary plane shown with dashed lines, from plane 2 to plane 3. Fisher et al6. use the concept of activated complexes, as given in the theory of absolute reaction rates." They show that the number of solute atoms per cubic centimeter per second which pc — Fig. 1-Diagram showing the arrangement of octahedral sites (x) in the fcc lattice. pass in the direction of diffusion from activated to new interstitial position is: ?where C is the concentration of the solute in atoms per cubic centimeter, l/m + is the fraction of new interstitial positions corresponding to motion in the forward diffusion direction (transmission coefficient), ?F* is the free-energy difference between the activated complex and the reactants when each is in its standard state at the temperature of the reaction (independent of temperature and composition in the case of carbon in austenite), y is the activity coefficient of the solute species, and, finally, ym is the activity coefficient of the activated complex (assumed constant). The flux of atoms moving in the forward direction through an area of 1 sq cm perpendicular to the direction of diffusion is therefore: m+ Ym l ' atoms per second where is the distance between planes. The blocking model states that a nearest-neighbor octahedral site of a given solute atom has a probability, f, of being inaccessible to other solute atoms. The number of available sites for diffusion on a given plane will, therefore, depend on f, which is constant, and Nu, the number of solute atoms on that plane. The effect is to have more available sites in the diffusion direction, thereby increasing the net flux of solute atoms. This is reflected in the transmission coefficient, l/m. To calculate the transmission coefficient for solute

Jan 1, 1970

By A. Valenzuela

During the last years, Chile has been the largest copper producer, either as concentrates or cathodes. Copper obtained via pyrometallurgy is produced by seven smelters, which have carried out modernization plans to increase smelting capacity or to achieve environmental regulations established in the Chilean legislation. Thus, the present work updates technological innovations in smelters, environmental regulations and presents solutions for SO2 handling, particulate matter and arsenic. Also, the authors emphasize the important role of CODELCO Chile, the most important state-owned copper company, in developing technologies such as EI Teniente Converter and EI Teniente Slag Cleaning Furnace,

Jan 1, 2003

By Saul Hissaci de Souza

A liga de alumínio AA 7075 recebida no estado T6 (conformada e envelhecida artificialmente) sofreu tratamento térmico a 300°C com o objetivo de causar o engrossamento das partículas de MgZn2, intermetálico responsável pelo endurecimento do material. As amostras foram então deformadas 45% em redução de espessura por laminação e recozidas isotermicamente a 200°C e a 250°C por tempos variados para estudar a cinética de amolecimento por meio de medidas de dureza Vickers. Os resultados indicam que a cinética de amolecimento em ambas as temperaturas de recozimento aproxima-se do comportamento previsto pelo modelo Johnson-Mehl-Avrami-Kolmogorov (JMAK) com boa concordância (coeficientes de correlação de 0,9725 e 0,9140 a 200°C e a 250°C, respectivamente), ainda que as micrografias ópticas da amostra recozida a 300°C por 4 horas não evidenciem a ocorrência de recristalização.

Oct 30, 2017

By R. H. Mullennex

Application of depositional analysis concepts is becoming an ever-increasingly more important and more useable tool in exploration and development of coals in the Appalachian basin. Over the past decade, a rather large number of studies, papers, and publications have addressed various aspects of depositional environments of coals and, to some extent, applications to development. As would be expected as regards a subject so complex as Pennsylvanian sedimentation in the Appalachian basin, certain academic studies have produced conclusions at variance in some aspects to those of other studies. Overall, however, there has been a building- block progression and general refinement with time of understanding of the depositional settings and other factors controlling Appalachian coal distribution, quality, and other minability parameters. Most attempts to explain coal seam characteristics have revolved around a basic deltaic model. Some have attributed certain seam attributes to upper delta plain deposition, other attributes to transitional-lower delta plain settings, and yet others to lower delta plain environments, and so on. While these approaches have provided valuable insight into some general coal characteristics, they are somewhat incomplete and are, in a sense, too broad for specific mine-scale applications. Further, it is apparent that in order for widespread peat accumulation to occur, there must be a drastic decrease in the energy of the depositional system and amount of sediment being brought in, compared to the active deltaic and coastal processes responsible for deposition of the large volume of clastic sediments that dominate the Pennsylvanian system of the Appalachians. Consideration of this fact implies that peats (coals) may not necessarily reflect depositional settings that are directly coincident with those associated with adjacent rocks. Cecil and Englund (1985) address this point, and quite correctly state that "the primary controls on major stages of peat formation are allocyclic processes involving paleoclimate, eustatic changes in sea level, and tectonics." While this statement is inarguable, it does not negate the importance and usefulness of depositional analysis in predicting reserve characteristics that may impact mining and marketability.

Jan 1, 1986

By Rainer Kahrger

This paper is a follow-up to the paper presented at the SME meeting in April of 1996. Since then, the El Abra facility has been started up, 9 months ahead of schedule, and has processed about 45 million tons of ore and produced over 700 million pounds of copper. For those unfamiliar with the El Abra materials handling and leaching facilities, a brief overview of the facility is provided. The paper will then deal in detail with such aspects of Conveyor 103, the long regenerative overland conveyor, including: actual running resistance starting and stopping procedures emergency brake test at 10,000 t/h Additionally, we shall take the opportunity to report on a catastrophic culvert collapse in October 1996, which stopped the conveyor abruptly at full speed and under high load condition, causing a belt breakage. We would like to use this opportunity to thank the management of El Abra and Cyprus Amax for providing assistance and allowing us to present this paper. The El Abra team deserves a great compliment for building this one billion dollar facility in record time in a remote area of a high-altitude desert with no existing infrastructure, and for bringing it so quickly up to full operating capacity. The El Abra management had to assemble a completely new operator team. Considering the above circumstances, it took a great effort by all involved to achieve success. The official performance test which was required by the lending banks was successfully concluded in November 1997.

Jan 1, 1998

The MineSight Schedule Optimizer (MSSO) is a new production scheduling tool developed by Mintec, Inc. using mixed integer linear programming (MILP) techniques. This tool was developed to solve the short- and medium-term schedule problems for surface and underground mining operations that involve multiple mining areas, multiple processes, multiple destinations and blending requirements. MSSO finds the optimum schedule in each period that achieves the objective while satisfying comprehensive product quality and quantity requirements as well as physical and technical constraints. Using the MineSight Planning Database (MSPD) as a central data hub, MSSO seamlessly works with MineSight 3-D (MS3D) block models and third-party data, MineSight Interactive Planner (MSIP), MineSight Haulage (MSHaulage) and MineSight Activity Planner (MSAP) to prepare data, formulate MILP models, calculate, report, fine-tune, save and visualize schedules. This paper presents the features and capabilities of MSSO. A case study is also given to demonstrate the applications of this new tool.

Jan 1, 2009

By David Hartley

United States Steel Corporation Minntac Mine is located at Mt. Iron, Minnesota, on the Mesabi Iron Range. The taconite pit is two miles long by a mile wide, with a maximum depth of 170 feet. This paper will deal with the radio remote control of locomotives engaged in the railroad haulage of crude ore and waste rock at this property.

Jan 1, 1970

By S J. Schafrik, E S. Gilliland, E C. Jong, J Waynert, C W. Weiss

Two commercially available through-the-Earth (TTE) communications systems were evaluated at an active underground longwall mine in West Virginia. One system utilises magnetic field (H-field) antennae while the other system utilises electric field (E-field) antennae to achieve communication. A large portion of this mine is overlain by an inactive gas-oil field composed of densely spaced wells. This feature provided a unique opportunity to determine the impact of cased wells on both TTE technologies. The following communication modes were investigated: surface to underground, underground to surface, underground to underground and real-time two-way communications. Standard deployments of the TTE systems using the manufacturer’s recommended procedures were able to achieve clear communications between underground and surface locations under certain circumstances. As a result, the design and deployment that will optimise TTE transmissions are unique to each system and to the specific area of the mine. This field study was conducted as a part of a larger multisite evaluation of available TTE systems in an effort to determine their operational sensitivity. The performance of these two TTE systems suggested that one may be preferable over the other depending on the conditions present during deployment.CITATION:Jong, E C, Schafrik, S J, Gilliland, E S, Weiss, C W and Waynert, J, 2015. Pairing magnetic and e-field through-the-Earth communication systems based on mine site conditions, in Proceedings Third International Future Mining Conference, pp 245–252 (The Australasian Institute of Mining and Metallurgy: Melbourne).

Nov 4, 2015