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By D. Olsen, S. Cole, J. Strid, G. Colzani

This paper focuses on the underground tunnel work at the Hollywood Water Quality Improvement Project (HWQIP) in Los Angeles, CA. The HWQIP is being constructed to provide a water distribution system to bypass the existing Hollywood Reservoir System, which supplies drinking water for 500,000 people. The major project features include, a 2.9-meter diameter 1,829 meter long bypass tunnel, a 1.8-meterdiameter 366 meter long utility tunnel, 3 jack and bore tunnels, two 136 million liters underground circumferentially wrapped pre-stressed concrete water storage tanks, associated piping, and mechanical facilities. The physical project location coupled with strong community involvement and stringent environmental concerns was a considerable driving force for this project located in the Cahuenga Pass area of the Hollywood Hills north of Los Angeles, CA.

Jan 1, 2001

By Donald W. Ross

Petroleum oils of widely different grades have long been clarified or decolorized by contact with fuller's earths. More recently, so-called activated clays have also been used for this purpose. Still more recently ouch clays have been used in the form of nodules termed "catalytic pellets." Clays of varied appearance and from different localities possess the desired bleaching qualities, but evaluation of such clays, so useful to the oil industry, has not been simple. Previous methods of identification and evaluation have largely followed procedures of production methods and were not primarily based upon the fundamental properties of the clays. Thus) a false assumption has grown up that) bleaching clays probably have no common properties on which a-method of comparison can be based. Fuller's earths and activated clays have a large absorptive capacity for the color constituents of petroleum and its products decolorizing is accomplished by bringing the oil into intimate contact with the clay and later separating the decolorized oil from the clay with its load of absorbed coloring matter. Former practice in absorbing "color" was to use the clay as granules or In' powdered form. More recent practice is to use clay pellets that are more abrasion-resistant than the granules. The oil is either filtered through a bed of clay, percolation method, or agitated on contact with the clay, contact method. Viscous oils are decolorized at an elevated temperature, so that their viscosity is lowered to the point at which thorough contact with the clay is insured. Nonhumidifying, nonoxidizing gas, such as dry steam or dry nitrogen, is used to seal such hot oil masses from the atmosphere.

Jan 1, 1948

It's long been suspected that there has been an increase in the incidence of premature failure of rock bolts in underground coal mines over the past ten years. As far back as 2002 a study found a possible contributor to such premature failure in some Australian coal mines might be linked to stress corrosion cracking (SCC) (Crosky et al, 2002). That study suggested the low impact toughness could be a major influence on the susceptibility to SCC of different steel compositions. A subsequent study involving laboratory corrosion tests however failed to confirm any link with metallurgical factors (Villalba and Atrens, 2007), a finding that is at odds with field experience. Some mine sites today are still reporting prematurely failed rock bolts to the rock bolt manufacturers; the failures are being identified at SCC induced. To this end a research project has recently been commissioned at University of New South Wales (UNSW), which aims to identify the environmental factors causing SCC, through field test sites and simulating the conditions within an accelerated corrosion laboratory. This paper outlines the methodology that will be used in this study.

Nov 25, 2010

By Dale Verran, Jared Orynik, Chad Sorba, David Bronkhorst

Denison Mines Corp. (“Denison”) has a 90% interest in the Wheeler River Uranium Project (“Wheeler River”) located along the eastern edge of the Athabasca Basin in northern Saskatchewan between the Key Lake mill and the McArthur River uranium mine. The project is host to the high-grade Phoenix and Gryphon uranium deposits, discovered by Denison in 2008 and 2014 respectively, which include combined Indicated Mineral Resources of 132.1 million pounds U3O8 (1,809,000 tonnes at an average grade of 3.3% U3O8). The Pre-Feasibility Study (“PFS”), completed in accordance with NI 43-101 in September 2018, is highlighted by the selection of the In-Situ Recovery (“ISR”) mining method for the development of the Phoenix deposit, with an estimated average operating cost of $4.33 (US$3.33) per pound U3O8. Phoenix is the highest-grade undeveloped uranium deposit known globally, including Indicated Mineral Resources of 166,000 tonnes at 19.1% U3O8 for 70.2 million pounds U3O8. The paper aims to provide a summary of Wheeler River and an overview of the proposed development of the Phoenix and Gryphon deposits according to the PFS completed for the Project. Further details regarding the PFS, including additional scientific and technical information are described in greater detail in the NI 43-101 Technical Report titled "Pre-Feasibility Study for the Wheeler River Uranium Project, Saskatchewan, Canada" dated October 30, 2018 with an effective date of September 24, 2018. A copy of this report is available on Denison's website and under its profile on SEDAR at www.sedar.com and on EDGAR at www.sec.gov/edgar.shtml.

Jan 1, 2020

By Wade Edward Speer

The Hiddenite District of Alexander County, NC has produced some of the world?s finest large emeralds since the first one was discovered 134 years ago. In fact, North America?s largest emeralds come from the district, making this one of the continent?s most unique gem deposits. In addition to emeralds, the Hiddenite District is also famous as the discovery site for the rare spodumene mineral hiddenite, first identified in 1881. Nowhere else in the world do these two minerals naturally occur together. The emeralds are a unique color variety of beryl (Al2Be3Si6O18) with trace amounts of Cr+3 and V+3 substituting for Al+3. The hiddenite (LiAlSi2O6) crystals also exhibit emerald green color due to traces of chromium. Consisting of three large deposits and numerous prospects, the district encompasses an area of 10 km2 (4 sq miles) centered on the small town of Hiddenite. Operations at the Adams, Ellis and North American Emerald Mines properties have been productive at irregular intervals since the 1880s. Currently, only the North American Emerald Mines property is being mined on a regular basis. Recent activity there has exposed a 3-hm2 (7.4-acre) pit with depths of 25 m (82 ft) that provides the best exposures of unweathered bedrock seen in the district in more than 120 years. Although no official records exist, public and private data indicate that the production of the entire Hiddenite District from 1880 to 2007 is about 70,000 carats of emerald and 20,000 carats of hiddenite. The bulk of the emeralds came from the North American Emerald Mine property (NAEM, formerly known as the Rist Mine) where sustained mining replaced the previous sporadic prospecting in 2000.

Jan 1, 2009

By Edward W. Parker

(Toronto Meeting, July, 1907.) NOTE.-The material from which this paper has been prepared was collected for the U. S. Geological Survey Bulletin, Contributions to Economic Geology, 1906, and appears also, though in somewhat more extended form without illustrations, in that publication. ALTHOUGH the briquetting of coals and lignites has been carried on for many years in Europe, and has reached a particularly high state of development in France, Belgium, and Germany, it has made comparatively little progress in the United States. The causes for the backwardness of the United States in this regard are several, and first among them has been the abundant supply of cheap raw fuel with which the manufactured article has to compete. With our millions of acres of coal-productive territory, from which the product can in most cases be cheaply extracted, it has appeared in many districts more economical to waste the slack or culm, which con¬stitutes a considerable percentage -of the product, than to attempt to save it at the additional expense required for briquetting. It is for this reason that the view in all sections of the anthracite-region of Pennsylvania is marred by the unsightly culm-banks which encumber the ground, and that in some of the bituminous-districts one sees huge piles of unmarketable- slack allowed to burn up in order to get rid of them. When the coal is of a coking quality, or when the slack can be used for steaming-purposes, these losses are not sustained, but many thousands of tons of what might be converted into usable fuel have been wasted every year simply because of the increased expense involved in its preparation.

Sep 1, 1907

By D. Hatfield

"Flotation plants typically aim to maximise recovery at or above a target grade. As the ore from the mine varies, operators increase or decrease the mass pull in different flotation banks by adjusting air and level set points in order to achieve target concentrate grade. A methodology has been developed to maximise overall recovery at target grade by determining the optimal mass pull for each bank. However, the approach of targeting equal grade for each ore type in the deposit leads to sub-optimal overall recovery. This is because some ore types sacrifice a large amount of recovery to reach target grade while others easily achieve target grade and can be processed at higher than target grade for little or no loss in recovery. Processing different ore types at different grades and blending the concentrates therefore gives a higher overall recovery.This paper presents a case study where an 80 year production forecast was made for a large Chilean copper concentrator in feasibility stage. A circuit model was created using SGS’s Integrated Geometallurgical Simulator (IGS) for the different ore types to be processed. The model was calibrated from standard rougher flotation tests (MFT), cleaner tests and from the results of plant surveys of similar operations. The pull rates for each bank in the circuit were determined to achieve an optimal graderecovery curve for each ore type. These curves were combined at different concentrate grades for each ore type to obtain the mathematically optimal overall recovery at target grade. The paper shows a methodology for obtaining an optimal combination of operating conditions for each ore type to maximise overall recovery at a set combined concentrate grade."

Jan 1, 2013

By Marius R. Campbell

Does mine-sampling show the commercial value of a coal, and if so, how should it be done? This question is often asked, but seldom answered. During the past summer, while engaged in securing coal for the Government coal-testing plant at St. Louis, I had an excellent opportunity to obtain information on this subject, and the results seem to furnish an answer to the questions propounded above. Sampling for the Geological Survey Coal-Testing Plant. In organizing the work of the testing-plant, it was decided that coal in car-load lots only would be accepted for testing, also that this coal should be loaded under the immediate supervision of a representative of the plant, so as to be certain that the car-load sample would be representative. As an additional check on the work, two mine-samples were to be collected from each mine visited, and these samples, as well as the sam¬ple from the car when it was received at the testing-plant, were to be carefully analyzed at the chemical laboratory, which was established in connection with the plant and operated under the direction of Prof. N. W. Lord, of the Ohio State University, Columbus, Ohio. Mine-Sanmhling:-Mine-samples were collected with great care by me and my assistants, Messrs. J. Shober Burrows, John W. Groves and Frank W. De Wolf. The dominant idea in the regulations which were adopted for mine-sampling was that it should be done in such a manner that the sample would have the same composition as the commercial output of the mine. .

Sep 1, 1905

By G. M. Rao, P. N. Deo

Graphite is soft and easily floatable but it is quite difficult to obtain high purity concentrate at coarse sizes. Chemical treatment can produce high grade concentrate but it is an expensive process. Graphite containing plus 96% fixed carbon (FC) with coarse flakes commands high price in international market. Such graphite concentrate containing plus 96% FC was produced in Indian Bureau of Mines (IBM) by using newly developed reagent (mixture of different hydrocarbons and terpenes, IBM/D7) instead of commonly used frothers viz. pine oil, MIBC, kerosine etc. and regrinding in a special type of mill with special grinding media instead of grinding in a conventional ball/ rod mill followed by cleaning. Both the new reagent (frother) and special grinding media are inexpensive and readily available. The process is under patenting. This paper focuses application of this new grinding methodology for flake size protection, and the new reagent for selective flotation of high purity graphite.

Jan 1, 1995

By A. C. Fieldner

The past full year of war has increased greatly the demand for virtually all kinds of fuel, and the Bureau of Mines research and service facilities have been extended to meet these unprecedented requirements. Liquid fuels, such as aviation and motor gasolines, are fundamental to modern warfare. Bituminous coal and anthracite are needed, not only to servo the expanded industrial program for which coal normally is used but also to replace natural gas, wherever possible, and fuel oil in the Eastern States, New England, and the Pacific Northwest. Railroad transportation with energy derived from coal is replacing much of the motor-vehicle transportation that has been stopped or curtailed to conserve rubber. Pulverized coal hoe been sound to be a satisfactory and cheaper substitute for fuel oil in metallurgical heating furnaces. Celloidal fuel - a mixture of coal dust and oil - may offer a partial substitution for curtain coal-burning equipment. Several industrial experiments have been made with this type of fuel. The expansion of the steel industry in connection with the war program has required a corresponding increase in the production of metallurgical coke and its associated byproducts - light oil, tar, ammonium sulfate, and surplus gas. If the war is of long duration and new reserves of petroleum are not discovered, wartime trends from fuel oil to coal probably will not be reversed.

Jan 1, 1945

By B. Yu, N. Verbaan, A. Mezei

The recent 20 years witnessed a boom and bust in the nickel laterite industry. Most notoriously is the story of the first three Western Australian nickel laterite projects which all suffered major ramp-up issues. Many hard lessons were learned by the industry and it has been widely reported that the major contributing factors included insufficient testing as well as a limited understanding of the materials handling characteristics at the front-end stage of the flowsheet. This paper compares the current "race to production" in the REE industry to the laterite industry 20 years ago and addresses the fundamental question: ‘Have mining and exploration companies with rare earth projects learned from past lessons and are they doing sufficient and appropriate testwork to prevent failure’? The authors will provide the perspective of a commercial metallurgical laboratory that has gone through the laterite cycle and is active in the present REE cycle.

Jan 1, 2014

By J. L. Henry

The development and status of technology for producing titanium from U.S. resource materials are summarized in this Bureau of Mines report. Commercially feasible processes and investigations of alternative procedures are reviewed in order to identify techniques that could make existing operations more effective or areas in which future research may lead to the development of new production methods. Procedures are described for producing concentrated titanium dioxide from starting materials such as sands, massive deposits, and mineral processing residues containing rutile, ilmenite, and perovskite; producing and purifying titanium tetrachloride from concentrated rutile, ilmenite, and titaniferous slags; reduction of titanium tetrachloride to titanium sponge metal using metallic magnesium or sodium; purifying and consolidating titanium sponge and scrap by arc melting or induction melting techniques; purifying sponge, scrap, and alloys by molten salt electrorefining; and electrowinning titanium from chloride salts.

Jan 1, 1987

By A. C. Johnson

The T. L. shaft of the Eureka Corp., Ltd., near Adams Hill, Eureka, Nev., was sunk in 1954 and 1955 to permit exploration and development of the lead-zinc-silver ore that had been indicated by drilling. This paper describes the sinking of the 4-compartment, vertical shaft to a depth of 1,127 feet and includes pertinent details of equipment, methods, and costs. A shaft crew of 10 men, supplemented by 13 hoistmen, topmen, carpenter, and shop crewmen, sank and timbered the 1,127 feet of shaft in 630 workdays. Total labor per foot of shaft was 107.95 man-hours. Supplies per foot of shaft included 20 pounds of explosives, 1.61 pounds of drill steel, and 200 board-feet of timber. Power consumption, including that required for pumping, averaged 3,726 kw.-hr. per foot.

Jan 1, 1958

By Fei Chen, Lesley J. Gaydos, Laurence M. Demers, Douglas C. Kuhn

The fibrogenic effects of silica in experimental animals and humans has been extensively studied (I 7, 20). However, the pathogenesis and molecular mechanisms underlying lung injury and fibrosis resulting from silica exposure remain to be elucidated. It is well-documented that silica can stimulate monocyte-macrophage lineage cells to produce cytokines and growth factors, including interleukin-I (IL- I) (20), tumor necrosis factor-ex (TNF-cx) (I 7), insulin-like growth factor-I (IGF-1) (4), and transforming growth factor-P (TGF-P) (24). Consequently, it has been suggested that the fibrogenic effect of silica may be mediated by cytokines in the fater stages of silicosis. During the early phase of interaction between silica and the pulmonary alveolar macrophage, several direct and indirect lines of evidence suggest that reactive oxygen intermediates (ROI) may play a pivotal role in silica- induced tissue damage (2I, 22). One of the most important components of and contributors to ROI is nitric oxide (NO) produced from L-arginine and molecular oxygen under the catalytic influence of NO synthase (NOS) (I 9). At present, at least three NOS genes have been cloned: a constitutive neuron NOS, a constitutive endothelial cell NOS and an inducible NOS (iNOS) (16). A number of factors have been shown to differentially induce iNOS gene expression in different cell lines including bacterial cell products and foreign antigens. During inflammation, NO is a double-edged sword in terms of the host immune defense mechanisms and the physiologic response to an inflammatory insult. The macrophage is one of the major cellular sources of NO. During the early phase of acute inflammation, NO produced from the macrophage appears to facilitate the clearance of pathogens and promotes a local relaxation effect on the microcirculation of vascular smooth muscle. When the production of NO is left unattenuated, especially under oxidative stress, direct cytotoxic effects of NO can emerge through the formation of peroxynitrite as a result of a reaction between NO and superoxide (2).

Jan 1, 1998

By Richard E. Bischke

Computer assisted finite element model analysis, originally developed to study stress distributions in aircraft, has been modified into a versatile mining program, that can be used to assist the engineer with predictions of mine subsidence. International Exploration, Inc. has developed an in-house finite element model program which incorporates a multitude of factors influencing mine subsidence such as mine design, physical rock properties, structure, faults, joints and topography. Finite element analysis of a mine model can mathematically determine the magnitude and direction of the principal stresses within each of the elements forming the model. By comparing the calculated in-situ stresses to the actual rock strengths, high risk regions within a mine can be identified. These potentially unstable regions of the mine can be allowed to fail within the model and the resultant stress redistribution and element movement calculated. Thus, the effects of the mine collapse at the surface can be predicted for the purpose of determining the potential damage, if any, that could occur to surface structures from deep mine failure. Stabilization materials can also be mathematically inserted into the model to design and analyze the effectiveness of subsidence prevention programs. Two examples are presented of the finite element program being used to predict mine subsidence at substantially different geologic and mining provinces in Pennsylvania.

Jan 1, 1984

By Volker Vogt, Wolfgang Sand, Eberhard Gock

"It was discovered that the selective activity of bacteria during the extraction of raw material concentrates by means of flotation could also be achieved with extracellular polymeric substances (EPS) excreted by bacteria. EPS, which is extracted by means of centrifuging bacterial cultures, can help to significantly reduce the use of cyanides, approximately 200,000 t/a of which are used for ore dressing today.The bacterium used was Acidithiobacillus ferrooxidans. In order to identify the bandwidth of the oxidation activity, 20 bacterial strains of the strain collection of the University of Hamburg were attracted to iron(II) sulfate and pyrite under defined conditions. All strains oxidized iron(II) sulfate ten times faster than pyrite.EPS has so far been derived from four strains. In general, EPS extracts are divided into a hydrophilic and a hydrophobic fraction. The hydrophilic fraction is composed of e.g. fucose, rhamnose and glucose; fatty acids such as dodecanoic acid, hexadecanoic acid, octadecanoic acid and nonadecanoic acid were found in the hydrophobic fraction.Pure mineral phases and mineral mixtures were used for the flotation tests. As opposed to current knowledge, the results were reproducible with technical flotation machines."

Jan 1, 2003

By A Jäger, J L. Lett, J Rachocki and B Mobilio

The Newcrest Mining Limited Cadia East Panel Cave mines near Orange, New South Wales, Australia commenced production 1200 m below the surface in May 2014. Understanding the mine-wide impact caving had on excavation stability was a primary objective to ensure a safe working environment as production ramped up in the Panel Cave 1 operation and establishment activities were implemented in Panel Cave 2. The impact of cave interaction between Panel Cave 1 and Panel Cave 2 and establishing monitoring systems to assist mine planning and production as both caves joined is explained in this paper. Monitoring tools such as a microseismic system, open holes, HI-cells, extensometers, fibre optic sensing, cave markers, closure monitoring, underground observations and damage mapping were used to characterise the performance and position of the cave back. The data and observations collected were compared to predictions from numerical and empirical methods and used to calibrate the numerical models for forward prediction and to develop site empirical design tools. The results and methodology for monitoring deep high-output caves are the key discussion points in this paper.CITATION:Lett, J L, Jäger, A, Thornhill, T, Rachocki, J and Mobilio, B, 2016. Geotechnical challenges in cave monitoring – a modern approach, in Proceedings Seventh International Conference and Exhibition on Mass Mining (MassMin 2016), pp 203–216 (The Australasian Institute of Mining and Metallurgy: Melbourne).

May 9, 2016

This paper investigates the effects of solids concentration and the addition of Dispersant S40 on the flowability of original and ground limestone slurries. A rotational viscometer with a concentric cylinder geometry and a controlled-stress rheometer with a cone-and-plate geometry were used to characterize the rheological behaviors of limestone slurries. The rheological behavior of original limestone slurries (<100 µm) is transformed through different types of flows with increasing solids concentration. The use of Dispersant S40 can improve the slurry flowability by decreasing viscosity and eliminating Casson yield stress. It is therefore used as a grinding aid for the wet ultrafine grinding of limestone. The rheological behaviors of ground limestone slurries vary with grinding from a starting dilatant flow-ability to a resulting pseudoplastic one with an evident Casson yield stress in combination with a thixotropic character. The appearance of pseudoplastic flowability combining thixotropy is related to the fineness of a ground product and its specific surface area, which are both correlated to solids concentration and the additive amount of Dispersant S40. In addition, the accurate rheological characterization of time-dependent fluids is dependent on the instruments used and operation conditions.

Jan 1, 2007

By James E. Parkes

The Silver Spring Transit Center is a new three-level transit center that will include bus loops for County, Metro and intercity buses, parking, and retail space. It replaces an existing bus station and connects to a busy metro rail station in downtown Silver Spring, Maryland. Significant site constraints in both plan and profile had to be dealt with in developing a design for support of the structure. Over 90 rock-socketed drilled shafts ranging in size from 3 to 7 foot in diameter were ultimately used to accommodate the limited space and large column loads, and to adapt to the variable rock surface at the site. Site access during design was limited due to the existing active bus station, so contract documents were adapted to include further explorations. Differences in anticipated and actual field conditions regarding the depth, quality, and variability of the rock had to be overcome in construction. Osterberg Load Cell testing during construction allowed for verification and optimization of the shaft design. Additional issues dealt with on this constrained site in an urban setting included construction staging issues, such as working around specialty contractors for tieback walls, blasting operations for rock excavation, productions issues for hard bedrock, as well as coordination issues with third parties, most notably the Washington Metro Area Transit Authority. Aspects of the foundation design and optimization, preparation of the contract documents to deal with the complicated nature of the project, and lessons learned from construction are also discussed.

Jan 1, 2011

By J. F. Shao, G. Duveau, W. Z. Chen, O. Ozanam

In this paper, we present a sensitivity study for the numerical modelling of hydromechanical coupling around a shaft in partially saturated claystone. Two representative constitutive models have been used: an elastoplastic damage model (IDEPLML) and an elastic perfect plastic model based on the Hoek and Brown failure criterion (H&B). A series of comparative studies have been performed with respect to main parameters involved in coupling process (mechanical, hydraulic and hydric properties). The emphasis is put on the evaluation of induced plastic, damaged and failed zone due to excavation and drying process. Dans ce papier, nous présentons une étude numérique paramétrique du comportement hydromécanique couplé d’une argilite partiellement saturé, lors du creusement et de la maintenance d’un puit L’étude paramétrique porte à la fois sur le type de modèle et sur les principaux paramètres (mécaniques hydrauliques et hydriques) intervenant dans le couplage. L’accent est principalement porté sur l’évaluation des zones plastifiées autour de l’ouvrage lors de la désaturation. In unserem Beitrag geht es um eine digitale parametrische Untersuchung über das hydromechanische Verhalten eines teilweise durchtränkten Tons beim Abteufen und dem Betrieb von Schächten. Die parametrische Analyse konzentriert sich auf den Modelltypus und auf die wesentlichen bei der Verbindung wirksamen Parameter, d.h. die mechanischen, hydraulischen und hydrologischen. Der Schwerpunkt liegt auf der Bewährung der plastifizierten Bereiche des Bauwerkes während der Austrocknung.

Jan 1, 2003