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By Phillip R. Moyle

In 1985 the U.S. Bureau of Mines evaluated the mineral resources of the Sheep Creek West Wilderness Study Area (ID-111-36A), Owyhee County, ID, for the U.S. Bureau of Land Management. The Wilderness Study Area consists of 11,680 acres centered approximately 20 miles south of Grasmere, 10. It contains no mines, claims, or prospects. No mineral resources were identified; however, a geode occurrence within and adjacent to the Wilderness Study Area, and minor amounts of placer gold along Sheep Creek, may be of interest to rorkhounds and recreational gold panners.

Jan 1, 1986

By A. Rios

ENAMl's Paipote Smelter commenced operations in 1951. At present, it processes 230,000 tonnes/year of green feed in a conventional smelter, which comprises one reverberatory furnace, two Hoboken, one Peirce-Smith converters and one rotary anode furnace. The feed is composed of 83% copper concentrate and 17% metallic copper precipitates, which results in a feed average grade of 32% of copper content. The final products are 75,000 tonnes/year of copper anodes and 48,000 tonnes/year of sulphuric acid. At present, the plant is undergoing a modernization to expand the smelter capacity to 300,000 tonnes/year of green feed and increase the sulphuric acid production to 100,000 tonnes/year. This will be achieved with the installation of an El Teniente Converter and an expansion in the acid plant. The work began in November 1991 and is scheduled to be in operaton by March 1993. The paper provides an overview of the modernization plans and results achieved to-date.

Jan 1, 1993

By Lung Cheng

Based on earlier tests that showed steel to be much more likely to cause frictional ignition than tungsten carbide, the Bureau of Mines redesigned coal-cutting bits to reduce the hazard of face ignitions. Two bit designs--a mushroom-shaped bit with a conical shank and a dove-tail bit with a rectangular shank--are described, as well as bit wear tests conducted in the laboratory and in an operating coal mine. In laboratory tests, for 1/8-, 1/4-, and 1/2-in-deep cuts and cutting speeds of 280, 500, and 660 ft/min, the mushroom bit had significantly longer tip wear life than the conventional bit; the dovetail bit was also superior to the conventional bit. Results of in-mine tests on the mushroom bit agree well with laboratory results. In-mine tests of the dovetail bit are underway.

Jan 1, 1983

By John Hickey

Management teams at mining companies begin to ask themselves whether to take a company public and, if so, how to do it as they approach the normal threshold for going public in terms of revenue and operating performance. Today, the expense of going public generally suggests the company has at least $20 million in annual revenue and at least $2 million in cash. The revenue number can be lower for mining companies with large reserves. In order to properly attract the investing public, the company must also be operationally strong with robust prospects. The company should have a strong management team and a consistent history of double-digit growth that will continue into the foreseeable future. Assuming the thresholds are met, a company?s management needs to weigh the pros and cons of going public.

Jan 1, 2012

By J. P. Josien, J. F. Noirel, F. Lahaie, P. Bigarre, M. Al Heib

ABSTRACT: In June 2001, a fatal rockburst affected a longwall face in the Houillères du Bassin de Lorraine (HBL), France. Subsequently, a large operation of in situ stress measurements by overcoring was carried out with two main objectives: providing input data for the back analysis of the dynamic event and characterising the stress field in the next panels to be mined for identifying other potential high-risk zones. This paper makes a synthesis of the results of the overcoring tests performed and discusses those results in connection with the mining context, numerical model predictions, laboratory rock test results and microseismic activity. KEY WORDS: Mine, rockburst, stress, overcoring, measurement. ZUSAMMENFASSUNG: Im Juni 2001 hat ein Bergschlag eine Kohlengrube des Houillères du Bassin de Lorraine (HBL, Lothringen, Frankreich) schwer beschädigt. Nach diesem Unfall sind Spannungsmessugen durch Überborung durchegeführt worden, mit zwei Hauptziele : 1/ Daten zu liefern für die Retro-analyse des dynamischen Gebirgsschlag und 2/ die Spannungen in den zukünftigen Ausbauen so gut wie möglich zu charakterisieren, um eventuele andere Risikozonen festzustellen. Dieser Artikel stellt eine Synthese der erzielten Ergebnisse vor. Er diskutiert diese Ergebnisse in Verbindung mit dem gesamten Kohlengruben Zusammenhang, mit den Ergebnissen von numerischen Modellierungen, mit der Labor-Charakterisierung und mit der microsismische Überwachung. SCHLÜSSEL-WÖRTER: Kohlengruben, Bergschlag, Spannung, Überborung, Messung. RESUME: En Juin 2001, un coup de terrain a gravement affecté une longue taille aux Houillères du Bassin de Lorraine (HBL) en France. A la suite de cet accident, une importante campagne de mesures de contraintes par surcarottage a été réalisée, avec deux objectifs majeurs : fournir des données d’entrée permettant la rétroanalyse du phénomène dynamique et caractériser au mieux le champ de contraintes dans les futurs panneaux exploités afin de détecter d’éventuelles autres zones à risque. Cet article présente une synthèse des résultats obtenus, et discute ces résultats en liaison avec le contexte d’exploitation, les résultats de modélisation numérique, de caractérisation en laboratoire et de surveillance microsismique. MOTS CLES: Mine, coup de terrain, contrainte, surcarottage, mesure.

Jan 1, 2003

By Gregg W. Davidson, J. Andrew McGlenn, Frank Huber

The Second Narrows Water Supply Tunnel will ensure system reliability in the event of a major earthquake and increase the Greater Vancouver Water District’s capacity to meet the long-term needs of a growing population. The tunnel will be 1,100 m long and 6.5 m in diameter (3,610 LF × 21.3 ft), constructed under Burrard Inlet between North Vancouver and Burnaby in British Columbia. It will be excavated through mixed ground conditions under high groundwater pressure, using a slurry TBM, between a 72 m (236 ft) deep shaft in soil and a 110 m (361 ft) deep shaft in rock. The completed tunnel will accommodate three large-diameter water mains that will be installed as part of the tunnel contract. This paper presents the project from design and contractor procurement, into the current construction stage describing some of the unique challenges encountered during the project development to date.

Jun 13, 2021

By Benkendorff P. N

Cement production in Australia approximates 6.5 million tonnes per year. Cement clinker is sourced from 15 plants which operate 28 kilns. Cement grinding is conducted at 14 of the clinker plants plus 7 grinding plants. Average annual capacity per kiln or plant is lower than in many overseas countries, but kilns introduced since 1970's have been of larger size more in keeping with size trends overseas, although still smaller than the large units overseas. Substantial economies in capital and labour costs can be achieved in large production units, particularly with dry process kilns using precalcination techniques in which part of the fuel is introduced in the static preheater section ahead of the kiln while the balance is added to the kiln in a conventional manner. Precalcination techniques have been introduced to the Australian cement industry but as cement transport costs form a major part of supplying diverse market areas, the size of kilns is likely to remain less than maximum owing to balance with distribution costs. The cement industry uses significant amounts of thermal and electrical energy which can be minimised by proper selection of equipment and technology. Labour costs are also significant and can be contained by automation and computer control of the process.

Jan 1, 1989

By Steve Davidow, Ashely E. Evans, Peter M. Kandaris

"Annually thousands of deep foundations are constructed across North America supporting high voltage transmission line structures. However, a recent state of the practice survey by the Deep Foundation Institutes’ Electric Power Systems Foundation Working Group discovered that the electric power utility industry lacks consistent foundation design guidelines. The survey identified a wide variability in design assumptions, a minimal understanding of risk based analysis, and a need to standardize design methodologies. This paper summarizes the state of practice in electric system foundation design and proposes a framework for risk-based foundation design by accounting for uncertainty from both loads and resistances. Loads derived from electric system codes do not necessarily provide a compatible level of reliability for the design of foundations, as they are a mixture of probabilistic and deterministic values. Load uncertainty is derived from variability in weather conditions, structural models and material properties, typically accounted for by code derived overload factors. Resistance uncertainty arises from variability in natural soil properties, resistance models, subsurface construction techniques, material sampling methods, and limited observations. A consistent methodology is offered relating nominal resistance capacity (strength) to structure loads and service state criteria. Discussion also includes the need for risk-based assessments to account for non-structure load influences (fluvial loads, scour ground loss, liquefaction, etc.).INTRODUCTIONNearly 40 years ago the Electric Power Research Institute (EPRI) embarked on a major research effort to optimize reliability and economics of transmission line foundation design. Strategies focused on improvements in design models, site characterization, exploration strategies and testing to reduce uncertainty and variance in analysis. Transmission line engineers realized that safety and reliability advancements in design based on probabilistic approaches, with a focus on the unique nature of transmission line, could better control risk and cost.Some transmission line professionals took full advantage of these advancements, particularly where research led to improved software and models. Yet, even after two decades of extensive research, by 1995 the industry still had made little progress in changing design habits. The majority of designers were still characterizing sites via deterministic methods, using loads that may or may not relate to a consistent probability of occurrence, and applying a traditional global factor of safety approach (Phoon, et al. 1995). The following two decades have seen even greater developments in software and reliability-based analysis methods, but old habits seem to die hard as recent surveys show less than half of design professional quantitatively assess risk in their design process."

Jan 1, 2017

By Frank E. Cash

Published or available data on safety in quarries are few except those pertaining to blasting issued by manufacturers of explosives. During the past 25 years the quarrying industry (including various types of quarries producing many different materials) has had a markedly improved accident experience. The downward trend has not been phenomenal or has it been uniform from year to year, owing to occasional major disasters; but from the information at hand it appears that improvement during the 25-year period has been definite.

Jan 1, 1941

By G. A. Brown

"Mining executives are becoming increasingly involved with decisions of the ""What would happen if ... "" variety. Potential changes in government policy, such as tax incentives, E.G.M.A. allowances, etc. affect the economic future of present and proposed mining ventures.This paper will discuss various measures of effectiveness normally used in assessing this future, such as discounted cash flow, etc., and will describe means of introducing uncertainty into the computations. As the recognition of risk and attitudes toward accepting it are very important in the life of a mine executive, there will be a brief discussion of utility theory and its application to risk analysis.Risk models are usually of a size to warrant the use of an electronic computer. Therefore, to demonstrate the simple interaction necessary between a financial analyst and such a model, data will be read into a remote computer from a time-sharing terminal in the meeting room. It will be shown that changes may be rapidly made and alternative policies investigated ""on line"" to a computer."

Jan 1, 1970

By J. M. Barker

The concept of global-market access through transportation efficiency is a concept whose time has come. The basis of this approach is customer satisfaction—the higher the better. But beyond what seems almost too logical is the question of how to achieve this market access. All industrial mineral exporters face stiff competition. Factors include proximity of competitive industrial minerals and substitutes, pricing pressure, political and cultural differences, currency fluctuations, communication problems, trade finance restrictions, and transportation imbalances. The following discussion will focus on transportation activities in global competitiveness, but the producer with the larger offering of services will often make the sale, not necessarily the low-cost producer (Cook, 2002). Some key concepts for global-market access are “the market concept,” just-in-time delivery, quality retention, and global customer service.

Jan 1, 2003

By Robert W. Van Dolah

The prevention of fires and explosions involving the combustibles and oxidants likely to be found in flight vehicles requires a knowledge of the flammability and related characteristics of these materials. This circular is a compilation of the available charactersilics data for a series of combustibles and oxidants of current interest. Vapor pressure data are presented for fluorine, oxygen, chlorine trifluoride, nitrogen tetroxide, nitric acid, hydrogen peroxide, ethylene oxide, hydrogen, ammonia, pentaborane, unsymmetrical dimethylhydrazine, monomethylhydrazine, hydrazine, and a series of hydro-carbons including decalin, tetralin, bicyclohexyl and other high-density fuels. In addition, flammability characteristics diagrams are included for each of the fuels in contact with air and, where available, other oxidants (for example, oxygen and nitrogen tetroxide). To assist in understanding these data, sections on definitions and theory and applications have been included. Each section is complete in itself and can be used separately. For example, a reader who is familiar with the general theory of combustion and detonation may find the data sections more useful than the definitions and theory and the application sections. However, since pertinent data are included in these sections, they should also prove useful to the experienced engineer interested in preventing fires and explosions.

Jan 1, 1963

By D. F. VanDine

The phases of a typical exploration program for sand and gravel resources include: (1) collection and assessment of existing information; (2) air photo interpretation and remote sensing; (3) ground investigation and mapping; (4) sampling and testing; and (5) data storage, retrieval, analysis and presentation. Depending on the purpose, time frame and funding available for the study, these phases, and the various techniques used within each phase, will vary. Once a sand and gravel deposit has been located, defined in size and quality, and found to be suitable for a given purpose, it can then be classified as a granular resource.

Jan 1, 1984

By Willemijn Husslage

Tata Steel Group At a glance ? Part of the Tata Group ?Tata Steel Group: ?Fortune 500 company ?Top 10 global steel producer ?Annual crude steel capacity of 28 million tonnes ?More than 80,000 employees ?Manufacturing operations in 26 countries across 5 continents ?Serving customers all across the globe ?Turnover 2009-10: $22.8 billion

May 1, 2011

By P. J. Cook

Comminution is one of the fundamentals of mineral processing, requiring large expenditures to be made on capital equipment, installation, power and maintenance. The trend toward lower grades and higher operating costs, mean mining operations are becoming increasingly marginal. The challenge is to improve and more importantly, utilise crushing and milling technologies that provide for reduced capital and operating costs whilst providing increased unit efficiencies. The Svedala Barmac Autogenous Crushing Mill presents such an opportunity by providing many of the cost savings and production increases required by its ability to produce a finer mill feed size and realise reduced energy consumption. This paper briefly describes the operation of the Svedala Barmac Autogenous Crushing Mill and reviews its benefits towards improving the efficiency of crushing and milling operations.

Jan 1, 1999

By Dave Marsh, John Goode, Niels Verbaan, Kevin Bradley, Henrie Notzl

The mineralogy of the Avalon Nechalacho deposit is complex with significant fractions of HREEs, Zr, and Nb found in refractory minerals such as zircon and fergusonite. Sulphuric acid baking followed by water leaching can be used to extract REEs from flotation concentrates, but acid baking does not completely "crack" the zircon and fergusonite, so the extractions of Zr, Nb, and HREEs are not high. An alternative flowsheet has been developed that is able to obtain significantly improved extractions of HREEs, Zr, and Nb from flotation concentrates or acid bake residues. This is accomplished by cracking the zircon and fergusonite minerals with caustic soda at high temperatures, followed by water washing to recover excess caustic soda and soluble sodium silicates and phosphates. REEs, Zr, and Nb in the solid residue can then be solubilized with HCl or H2SO4. This paper highlights some of the findings from an extensive laboratory program and discusses several flowsheet implications.

Jan 1, 2014

By W. R. Cowan

The availability of mineral aggregates for construction purposes is rapidly declining through inadequate resource planning. restrictive zoning and legislation , and competing land uses. The Geological Branch of the Ontario Ministry of Natural Resources has undertaken to provide aggregate inventory reports for all townships designated under The Pits and Quarries Control Act, 1971, and eventually for all towns hips in heavily populated areas. The reports contain maps and recommendations for extractive zoning by municipalities; of necessity only the largest deposits are given priority recommendations. It is intended that these reports should improve the resource planning in areas underlain by large aggregate deposits. The inventory is only possible because a concentrated effort has been made to map the Quaternary geology of populated areas over the last ten years. Future needs require that we develop methods to determine the extent of poorly defined and buried aggregates and that we look for natural alternatives.

Jan 1, 1978

By Y. M. Zhao

The separating performance of a pilot dry beneficiation system using a gas-solid fluidized bed was investigated with coal from South Africa. The coal used for the study has a low inherent moisture content, a moderate ash content, a moderate volatile content, a low sulphur content and a high calorific value. Its washability is moderate. Experimental results show that the separating quality of the fluidized bed drops gradually as the feed-coal particle size decreases. The probable error, E, values for 50?25mm, 25?13 mm and 13?6 mm coals were 0.04 g/cm3, 0.06 g/cm3 and 0.09 g/cm3, respectively. The cause of the differences in separating characteristics was analysed by particle dynamics and numerical modelling. Furthermore, the pilot fluidized bed was employed to separate 50-6mm coal. In this experiment the coal ash content was reduced from 23.74% to 11.79%, with a probable error, E, value of 0.07 g/cm3and a recovery efficiency of 98.26%. This indicates that the fluidized bed is applicable to the separation of coal from South Africa and has good separating performance and wide applicability. Keywords: feed-coal particle size; gas-solid fluidized bed; dry coal beneficiation; numerical simulation.

Jan 1, 2010

By Lala Zhao, Yuemin Zhao, Guangyuan Xie, Chusheng Liu, Chenlong Duan

"Screening is an important means of size classification used on granular or particulate materials. The vibrating modes of screen separator have a great effect on the screening process. Elliptical vibration mode is a complex motion mode which gets the common characteristics of both linear and circular vibration modes. However, the fundamental motion and screen penetration of the particles on the elliptically vibrating screen deck are still poorly understood. A numerical study of the motion of particulates flow along an elliptically vibrating screen deck is presented by means of a three dimensional Discrete Element Method (3D-DEM). The motion characteristic of the particle flow is analyzed at a particle scale. The effects of vibration amplitude, throwing index, vibration direction angle and screen deck inclination angle on the screening process are discussed. The results show that the particles average velocity increases linearly with the increase of vibration amplitude, throwing index and screen deck inclination angle, but decreases linearly with the increase of vibration direction angle. The screening efficiency is highest when the vibration amplitude, throwing index, vibration direction angle and screen deck inclination angle are 4.5 mm, 3.3, 40° and 6°, respectively. This work is helpful for developing a deep understanding of particle motion on the elliptically vibrating screen and for optimizing screen separator designs."

Jan 1, 2014

By Song Yongxue

During the design and operation stages of a block caving project, a large amount of research and development work has been undertaken in the Tongkuangyu Copper Mine. This paper presents the research achievements from these studies, including a rock mass quality evaluation method, cavability prediction, fragmentation evaluation, caving mechanisms, a computerised production scheduling model and the optimised draw control system. The main features of the block caving system in the Tongkuangyu Copper Mine are also discussed.

Jan 1, 2000