Search Documents

By D. M. A. Flight, P. M. Green, J. A. Plant, P. R. Simpson

Paper presented at Mineralisation in the Caledonides, the Mike Gallagher memorial meeting held in Edinburgh, 27-28 June 1996. The British Geological Survey's regional geochemical database is used to identify the patterns associated with the various mineral deposit types and to examine the extent to which their distribution reflects the presence of long-lived metallogenic provinces in the crust. Image analysis provides new insights into the setting of the mineralisation, geochemical constraints on tectonic models of Caledonide evolution and evidence for terrane amalgamation and large-scale processes. There is evidence that much of the mineralisation reflects the presence of long-lived provinces with a distinctive geochemistry reflecting their origins as zones of crustal extension. In the case of the Middle-Upper Dalradiam sedex deposits, the relationship between geochemistry and tectonic setting is direct. In other cases, rocks deposited in extensional zones appear to have acted as reservoirs of ore-forming elements which were further concentrated during later events

Jun 19, 1905

By A. Holeyman

The displacement compaction piles described in the paper are installed using a heavy casing or tube and an internal drop hammer. The casing which initially is closed at the bottom by a sand plug displaces the surrounding soil during the driving. Additional sand is rammed down through the casing during the extraction of the casing. The applications and limitations of the method are reviewed in the paper. The importance of checking the sand compaction piles during and after the installation is stressed. Indications of the compaction of the surrounding soil during the driving can be obtained by comparing the initial and the redriving logs of the casing as well as from the volume of sand added. A method to estimate the increase of the mean cone resistance as measured by CPT tests in sandy and silty soils is presented. The governing parameters are the volume of the added sand, the granulometric index and the initial cone resistance.

Jan 1, 2010

By W. C. Blanchard

Time Domain Reflectometry (TDR) is a remote sensing technique using active backscatter. This technique is applicable to the testing for faults and multiple partial faults on cable. The battery operated hardware developed on this con¬tract has tailored this technique for testing of mining equipment trailing electrical cables. The processing of-t-he back-scatter is accomplished using a microprocessor. The visual output from the hardware to the operator is; the type, magnitude and distance to the cable fault in a numerical format. This greatly simplifys the use of this techniques for the operator.

Jan 1, 1980

By H. A. Wright

This report assesses the economic, legal, institutional and technical factors that affect the current and future status of implementation of mine monitoring systems in the United States. It begins with a description of a poll of the Mining Production Research Committee and the Mine Monitoring and Communications Committee of Bituminous Coal Research that was conducted to establish industry monitoring needs and constraints. Existing systems in the United States and foreign countries are then reviewed and compared with the requirements set forth by the industry committees. At the same time, state and federal mining laws are reviewed, and equipment currently available from suppliers of mine monitoring systems and components is discussed. A framework for cost/benefit analysis is established and a series of case examples for various monitoring functions are presented. The total values of the market for mine monitoring systems in 1980 and 1990 are estimated on the basis of industry statistics and system cost estimates.

Jan 1, 1982

By John C. Machisak

INJURY and employment figures for nonmetal mines and mills in 1959 are presented in this publication. Data for nomnetal mines are presented separately from those for nonmetal mills. The Bureau of Mines is authorized to send questionnaires to the nonmetal mining industry each year requesting their voluntary submission of injury experience and employment data. The voluntary response to these requests has contributed greatly toward the promotion of safety in the industry, and every effort has been made to make the information as complete as possible.

Jan 1, 1963

By Darren Medd

Kumtor Gold Company (KGC) currently operates the 500,000 tonnes per day Kumtor open pit gold mine located in the Issyk-Kul region of the Kyrgyz Republic at an elevation of more than 4,000 m. To supplement the open-pit mill feed with high grade underground ore from outside the current pit limits, KGC started pre-production design and development of the underground mine for the SB ore zone in late 2006. The initial phase of pre-production development consists of exploration and haulage declines which, upon completion, will provide ventilation and access to the underground mine. Design and construction of these declines presented many challenges to the project team considering the mines unique location at high altitude, the limited experience with Western underground mining techniques in the Kyrgyz Republic, and the impact of the nearby Davydov glacier and resultant ground conditions. Completion of the exploration and haulage declines was undertaken jointly by KGC and mine contractor, J.S. Redpath Limited (Redpath). The initial phase of development including several ground falls provided detailed information on geotechnical ground types and conditions that were useful in determining the overall mine design and methodology for production. This paper covers the various aspects of the design and construction process of developing the declines under the glacier, minimizing the likelihood of further ground falls, and the journey of both KGC and Redpath which led to the successful breakthrough between the declines on 01 July 2012.

Aug 1, 2013

By W. A. Naismith

On 16 July 2004, at 07:10 a collapse of about 1.8 million m3 (about 4 ½ million tons) took place on the north wall on Nchanga Open Pit. This collapse was the result of a developing instability that was first identified when the benches in this area were exposed during September 2002. The NOP geotechnical and survey departments closely monitored the development of the failure. Control measures were implemented to reduce risk to men and equipment. These measures were continually improved and adjusted in reaction to observations and changing conditions. The purpose of this paper is to describe in detail the monitoring results that were obtained both by traditional methods and the novel slope stability radar system (SSR). Difficulties encountered in establishing critical deformation levels and deformation rates that can be used to predict the onset of collapse are described. Details of the monitoring and control measures, which led to the successful completion of mining in the area, are also described in this paper.

Jan 1, 2005

By R. D. Rosenkranz

The Bureau of Mines has investigated the availability of copper from 272 deposits in market economy countries. The deposits studied have demonstrated resources totaling 413 million metric tons of contained copper and account for more than 90 pct of the reserve base for market economy countries. Using data gathered as part of its Minerals Availability Program, the Bureau performed geologic, engineering, and economic evaluations in order to determine the copper production potential of each deposit. At the 1981 copper market price of $0.85/lb, the deposits studied could economically produce an estimated 88 million metric tons of copper (allowing for profit computed at a 15-pct rate of return), primarily from mines operating at the time of the study (1981). At this price, producing mines in market economy countries could economically produce only 2.1 million metric tons of refined copper per year. However, actual 1981 production was 6.2 million metric tons, indicating that many mines continued to operate even though they were unable to cover all production costs. For U.S. producing mines, the estimated average cost of production per pound (including profit at a 15-pct rate of return) was $0.15 higher than the average cost in other market economy countries.

Jan 1, 1983

By V. R. Miller

The Bureau of Mines developed and evaluated a detecting and sorting device to separate the copper-bearing portion from the barren portion of Michigan native copper ore in the minus 4- plus 1-inch size range. Small-scale sorting tests were also conducted on minus 1- plus 1/2-inch material from the Centennial No. 6 mine, using a previously developed system that was modified to increase sensitivity. Results showed that, with the added sensitivity, 85 to 90 pct of the copper in the minus 1- plus 1/2-inch material could be recovered in about 50 to 60 pct of the fraction. Sorting tests on minus 4- plus 2-inch and minus 2- plus 1-inch fractions from the Centennial mine were conducted with the large sorting system. Results showed that 86 to 93 pct of the copper was recovered in 43 to 64 wt-pct of the sorted fractions. Combining of concentrates from the two fractions resulted in a recovery of 90 pct of the Popper in 55 pct of the weight. The composite concentrate contained 2.40 pct copper, and the tailing analyzed 0.33 pct Cu; the head sample assayed 1.46 pct Cu.

Jan 1, 1978

Steady increases in longwall production have required operators to apply greater quantities of ventilating air in an effort to control and dilute respirable dust. Significant increases in shearer speeds necessitate that longwall supports also be advanced at a faster rate. Both of these factors may contribute to overall respirable dust levels on the longwall face because as supports are lowered and advanced, broken material falling from the top of the canopy is entrained directly into the air stream. To address this issue, the Pittsburgh Research Laboratory collected respirable dust samples from four longwall faces to characterize shield-generated dust. This paper investigates the influence of air velocity and shield advance rates on respirable dust levels. Also discussed are engineering controls currently used to reduce shield dust and alternative controls being investigated by the National Institute for Occupational Safety and Health (NIOSH).

Jan 1, 2009

By Thomas C. Shapiro

Introduction In recent years - even months - the number of articles on computers has increased rapidly. One can hardly pick up a newspaper or magazine without seeing a computer-related article. The article usually explains how the computer will change our lives. Many of us have some concern about the nature and type of change. For most of us, though, the problem is lack of information and understanding about how computers work. In other words, how do we make cost-effective decisions about computers? This three-part series will explain, simply, what a microcomputer is, how it works, and how to decide if you need one. This first article will define terms and briefly discuss areas where computerization might be economic. The second article will discuss geology and mining applications. The third article will discuss plant, administrative, and geotechnical areas as well as the future of software development in the minerals industry. Terms and Concepts All computers have input and output devices and a central processing unit (CPU). Information - instructions and data - is communicated to the computer by means of input devices. These instructions to the computer are converted into language that the computer understands. This causes the instructions to be carried out in the CPU. The result of these operations is translated back into language that we understand. This information is then sent to output devices such as printers and video display tubes. Traditionally, peripherals were devices separate from the main-frame (the CPU and memory) and were used to input, output, and store information or instructions. Today, peripherals perform the same functions though they may be housed in the same cabinet as the CPU and memory. Historically, peripherals included all input and output devices not part of the mainframe. Input devices include keyboards, magnetic tape, and card readers. Tapes and disks are input as well as output devices. Output devices are printers, CRTs (Cathode Ray Tubes), and any mass storage device capable of storing data when directed to do so by the computer or the program. In fact, any mass storage device that can give the computer data when requested is an input device. Mass storage devices include floppy disks (thin, round sheets of plastic covered by metal particles), and hard disks. The latter are thicker and more densely coated with metal particles. This allows much more information to be stored. Another type of mass storage is magnetic tape. Its type and size varies widely. Processing and Storage Any computer understanding must include how instructions and data are processed and stored. Information is stored as a positive or a negative field known as a "bit." There are eight bits in a byte. The bits can be represented as either a one or a zero. Thus the code for a byte representing the numeral one is 00110001. The byte representing the letter A is 01000001. These codes are from the American Standard Code for Information Interchange (ASCII). ASCII defines the standard set of characters including alpha, numeric, and special characters. The computer's memory has allocated locations where instructions as well as incoming information can be stored. All information and instructions are stored as binary numbers bit by bit - zeros and ones. The amount of data that can be stored is referred to as either thousands or millions of bits or bytes. The letter "K" is used to designate one thousand units. The letter "M" is used to mean one millon units (one meg). Disks Thus, a 113-mm (5 1/4-in.) floppy disk - double sided and double density (DSDD) - contains 320,000 bytes (characters) or 320K. This is about 164 double-spaced, type-

Jan 2, 1984

By G. W. Jones

The results presented in this report deal with the elimination of explosion hazards of ether-oxygen mixtures by the addition of helium. The method is based upon the fact that every combustible gas, vapor, or dust will not burn or explode when the oxygen content of the mixture is reduced below certain definite values. These critical oxygen values are usually different for each combustible, varying with the percentage of the combustible present in the mixture and also with the inert gaseous material used to reduce the oxygen content of the mixture.

Jan 1, 1941

By K. K. Kershner

The purpose of this investigation was to develop methods, on a laboratory scale, for recovering tin from Bolivian metallurgical slimes. Petrographic and chemical analyses were made of slime ore fractions from several well-known tin operations. High percentages of the total tin were volatilized as chlorides at temperatures below 600° C. Under optimum conditions reaction rates were relatively rapid, and the chloridizing reaction approached completion. Owing to the low temperatures involved and the high yields of tin, the process was considered to have possibilities for treating Bolivian slimes on a commercial basis. ACKNOWLEDGMENTS Appreciation is hereby extended to the Patino Mines and Enterprises, Inc., of Bolivia, for supplying slimed tin ores that were used in the experimental work. This company has since been nationalized.

Jan 1, 1959

By R. Raghavaraju

Estimation of the dynamic stress field in terms of its amplitude and decay around a blast hole is a key input parameter in all numerical modeling and blast prediction exercises. However, there is very limited information available in literature on these critical parameters, which would be considered essential in any blast modeling exercise. A laboratory-scale experimental study has been carried out in two different rock types to study at very close range the stress wave decay from a blast hole at distances ranging from 3 to 10 borehole radii. The single–hole blasting experiments employed a centrally located detonating cord (5.3 g/m) in 6 mm(1/4 inch) and 10 mm (3/8 inch) boreholes. The coupling medium employed was air and water, in addition to using a thin-walled copper tube in intimate contact with borehole wall to prevent of penetration of explosion gases into the emerging cracks. The paper describes the nature (amplitude and decay) of the transmitted shock pressure and their evolution in the two rock types for these various experimental conditions, which are present to varying degrees in all blasting operations.

Jan 1, 2014

A President, soon after he is appointed, sees looming ahead of him the Presidential Address; and in something approaching despair wonders what he can possibly talk about which might hold the interest of his audience. After various casts about, it occurred to me that perhaps prospecting, and more particularly prospecting in Australia, might provide a subject. This is because, 'in the first place, 'prospecting is passing from the stage of chance surface discovery to that of systematic search applying scientific methods to theproblems involved, and in the second, it is the section of the industry with which I have been concerned through much of my: working life. As it makes an address of this sort more interesting if it includes specific reference to actual experience, I hope you will bear with me in such references to actual prospecting as I may use to illustrate the argument. Prospecting has always carried the glamour of sudden wealth. The picture of the prospector engaged, perhaps for years, in fruitless search suddenly coming on riches beyondhis hopes is, deeply etched in the Australian imagination. In few other places has the fervour of prospecting run higher than it did in Victoria in the generation beginning little more than a century ago following the discovery of gold.People arrived from overseas in great numbers. Most of them proceeded to: the goldfields. They moved in thousands from new find to new find. In 'so doing' they determined much of the course of the State's development. The experience of prospectors led them to formulate all sorts of theories little impeded by awkward facts, to account for the apparently unpredictable occurrence of gold.The ideas which men followed, occasionally to success, and which they were prepared to back with all they had were strange and, various, many stories are told of them.

Jan 1, 1959

By C. Sawmliana, P. Pal Roy

Near-field blast vibration response of restrained pipelines either buried or exposed was studied during rock excavations at sensitive locations for Stage-II (4x500 MW) commissioning work in a super thermal powerplant of the National Thermal Power Corporation Ltd. (NTPC) of India. The existing running plant of capacity 1000 MW has many important installations including pipelines of varying diameters. These pipelines were very close to the blasting locations (mostly within 12m). Blast optimization and consequent monitoring of vibrations were carried out simultaneously for more than 250 experimental blasts conducted by the authors. This paper emphasized, particularly, on the safety of pipelines and their responses due to repeated blasting impacts. A few guidelines supported by theoretical derivations are provided for futuristic research.

Jan 1, 2001

Vitrinite reflectance forms the basis of a study of coal rank variation in two areas of the Upper Hunter Valley, New South Wales, on the northern margin of the Sydney Basin. A selective analysis procedure, based on samples rom twenty-two boreholes, has resulted in a small range of reflectance values for each sample and consequently a high degree of significance for calculated mean values. The patterns of rank distribution derived from these data have facilitated an interpretation of the rclative timing of coalilication and deformation in each area.This study provides support for the suggestion by several authors that there were at least two periods of folding in the tJpper Hunter Valley. In the Hebden-Ravensworth area, minor folding took place after most of the coalilication was completed.To the west, in the region of the Muswellbrook Anticline, coalification occurred during or after the formation of this major structure. Tectonic instability during deposition of the Singleton Super-Group, in the region of the Hunter-Thrust on the basin margin, is evidenced by rank variation suggesting differential subsidence across this zone.

Jan 1, 1980

By L. Maday, V. J. Perrone, M. B. Gilbert

INTRODUCTION The Brightwater conveyance system project in King County, Washington consists of constructing about 21 km (13 mile) of effluent and combined influent and effluent tunnels. The influent tunnels will collect sanitary sewerage from the service area and convey it to the new wastewater treatment plant (WTP) site at Route 9 in Woodinville, Snohomish County, Washington. The effluent tunnels will convey treated effluent from the WTP to an outfall at Puget Sound. The tunnels will be constructed primarily under residential areas, busy suburban roads and state highways. This 21 Km (13-mile) soft ground tunneling project faced many design challenges because of the geologic and hydrostatic conditions, long tunnel reaches, and large overburden depths. Boring depths typically varied from 45.7 M (150 ft) to 114 M(375 ft) with a maximum depth of 185.6 M (566 ft) deep. Conventional empirical methods for non-mountain terrain based on a 1:1 ratio of drilled footage per foot of tunnel bore (National Research Council, 1984) for evenly spaced borings provided a good start for the Phase 1 explorations. However a continuation of this approach with closer spacing was deemed inadequate by the geotechnical team for efficiently allocating geotechnical exploration resources for the final design. This paper presents a rational approach that was used to evaluate the value of a particular geotechnical exploration boring, pump test or other in-situ test. The method of analysis, which was initially developed for rock tunnels (Einstein et al., 1978), was modified for the Brightwater project. The method considers the potential construction cost risks resulting from variable geologic conditions, the cost and reliability of the geotechnical exploration and the earned value (cost risk reduction) of performing the geotechnical exploration. PROJECT DESCRIPTION In total the land portion of the conveyance system will include approximately21 Km (13 miles) of tunnels ranging in size from 3.0 to 5.2 M (10 to 17 ft) minimum inside diameter with overburden depths of 30.0 to 168 M (100 to 550 ft) and

Jan 1, 2005

By G. W. Jones

The results presented in this report deal with the elimination of explosion hazards of ether-oxygen mixtures by the addition of helium. The method is based upon the fact that every combustible gas, vapor, or dust will not burn or explode when the oxygen content of the mixture is reduced below certain definite values. These critical oxygen values are usually different for each combustible, varying with the percentage of the combustible present in the mixture and also with the inert gaseous material used to reduce the oxygen content of the mixture.

Jan 1, 1941

By H. Zhu

Coal desulphurization by flotation is often difficult due to the surface oxidation of coal pyrite. Scanning electron microscope (SEM) and X-ray diffraction (XRD) were adopted to obtain detailed information about the surface oxidation of pyrite. Fresh pyrite surfaces were found to be hydrophilic, and to turn hydrophobic after initial oxidation, with oxidized products such as polysulphide FeSx and free sulphur. The oxidized products on the pyrite surface were reduced by an electrochemical method, returning the surfaces to a hydrophilic state and thus increasing the separating efficiency of coal from pyrite by flotation. Key words: surface oxidation, pyrite, SEM, XRD pattern, electrochemical modification.

Jan 1, 2002