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By John R. Thalimer

For the past four years the U.S. Bureau of Mines has investigated the early detection of insulation failure in squirrel cage induction motors. Data modeling techniques based on values calculated from a motor's voltage and current phasors were used to produce a pair of polynomial equations that calculate a motor's insulation leakage current and power. This paper describes a prototype system using these models that monitors six motors on a continuous miner for insulation leakage in order to anticipate insulation failure. The system consists of a motor-data system for each motor on the machine, a control computer located some ' distance from the miner, and a serial bus to interconnect these items. Each motor-data system consists of an analog interface to the motor's voltages and currents, a single-board computer that reads digitized data and calculates voltage and current phasors, and a bus node that interfaces the single-board computer with the serial bus. The control computer can request and receive phasor data from any motor-data system on the bus. Using models developed at the Bureau, the control computer calculates and displays two deterioration values for each motor, one for leakage current and the other for leakage power. These values are then stored into a database from which the user can display them over time.

Jan 1, 1992

By D. R. Wilburn

This summary of international mineral exploration activities for the year 2005 draws upon available information from literature, industry and U.S. Geological Survey (USGS) specialists. It provides data on exploration budgets by global region and mineral commodity and identifies significant mineral discoveries and exploration target areas. It also discusses government programs affecting the mineral exploration industry and presents analysis of the mineral industry based on these data. Two types of information are reported and analyzed in this annual review of international exploration for the year 2005. They include budgetary statistics provided by Metals Economics Group (MEG) and information on regional and site-specific exploration activities in 2005 compiled by the USGS.

Jan 1, 2006

By Frank R. Cappuccitti

This paper will deal with current market trends for sulfide mineral collectors in three distinct parts; the global market for sulfide collectors, collectors as tools to solve mineral processing problems and new collector Research in the 1990's. The global market and manufacturing of sulfide collectors will be detailed as well as the trend towards using increasing amounts of specialty products. The use of Total Quality Concepts for laboratory and plant evaluations of new products will also be discussed. Research in the 1990's for sulfide collectors will need to focus not on the development of new chemical species but on the application of the new technologies that have already been developed.

Jan 1, 1994

By A. M. Marabini, G. Belardi, V. Alesse, M. Acosta

Sotiel mine is situated in the Iberian Pyrite Belt in southern Spain, some 40 km north of the port of Huelva. Although mining operations at the site date back to Roman times, the present mine came into production in 1983 and 5.6 million tonnes of ore had been extracted by 1993. The orebody is volcano-sedimentary and consists of fine grained copper, lead and zinc minerals in massive pyrite surrounded by slates and volcanics. Prior laboratory research had resulted in the synthesis of a new collector, belonging to the MercaptoBenzoOxazole (MBO) class that acts selectively towards Cu and Zn minerals after activation with CuS04. The MethylMercaptoBenzoOxazole (MMBO) version of this collector had been used for the laboratory flotation of Cu minerals and sphalerite activated by CuS04. This resulted in identification of the optimal physicochemical conditions for laboratory-cell flotation of the two minerals from samples of complex sulphide ores, and subsequently the reagent has been tested in the Sotiel plant (Spain). The plant has three flotation sections. With conventional re-agents, the first section yields a Cu concentrate grading 21% with a total recovery of 29%, and the second one yields a 40% Pb concentrate with total recovery of 34% and a 47% Zn concentrate with total recovery of 78%. Application of the new synthetic reagent in the copper and zinc circuits produces a more selective process with a decrease in re- agent concentration grade and recovery are increased by 2 and 9 points respectively in the case of Cu and by 1 and 3 points where Zn is concerned. Moreover, the penalty elements in the Cu concentrate are halved.

Jan 1, 1995

By A. D. Walters

Computer simulation models of preparation plant operations and cost analysis have been used to determine the profitability of individual coals. The model's input consists of raw coal size and washability analysis, operating cost data, and raw coal and clean costs. The model's output predicts yields, qualities, costs and profitability for an individual coal.

Jan 1, 1987

By Brian E. Gombos

During early stages of the detailed design for Detroit?s Upper Rouge CSO Tunnel Project, a Value Engineering Recommendation suggested the design team investigate alternative concepts to the usual cast-in-place or precast concrete lining system for the Project?s many smaller diameter Deaeration Vent Shafts. The resulting design investigation produced not only an alternative lining system, but lead to a proposed non-conventional approach to shaft installation means and methods through soil and rock necessary to construct the permanent shaft lining system. This paper will outline and summarize the technical issues, contractual restrictions, and cost considerations that eventually lead to the final shaft design

By Leslie S. Halasz

This paper describes the techniques implemented at Randfontein Estates to develop twin-haulages at 'high speed'. An operation which culminated in the world record advance for twin-end multiblast cyclic development in hard abrasive quartzites. A major expansion project was planned for the mine, with the sinking of a third twin-shaft system (to be known as Cooke No. 3), to raise the level of ore production from 3 500 000 to 5 000 000 tonnes per alumm. Subsequent redesign of the proposed shaft system as a single 9 m brattice wall shaft took place, reducing the planned shaft sinking period by 12 months and saving an estimated R 250 000 (U.S. $ 330 000) in sinking costs. The advancement of the Cooke No. 3 Shaft sinking and development programme necessitated a rapid excavation schedule for two interconnecting twin-haulages from the existing Cooke No. 2 twin shaft complex to provide a second means of egress. An early holing between the two shafts would provide significant financial and technical benefits. Pre-development and equipping of shaft pillar excavations would enable a rapid shaft production build up and blocking out of at least one year's ore-reserves.

Jan 1, 1983

Ventilation network modeling in mine planning dates back at least three decades, but it is not widely accepted and/or practiced until the last decade, thanks to the advent of modern computers with their increase d speed and storage space. There are at least half a dozen such modeling software packages available on the market each with different features and acceptance. This paper compares five popular software packages,?? VnetPC Pro, MineVent, VentSIM Visual, VentGraph and MFIRE 3.0. A case study using Missouri S&T?s Experimental Mine is conducted to compare the five software packages in features, interface, output display and user-friendliness.

Jan 1, 2012

By Kumar Vikram

Rich reserve of prime quality limestone in east khasi hills of India and abundant quantity of low-cost fuel (Natural Gas) in Bangladesh made Lafarge Surma cement limited a joint venture company of Lafarge France and Cementos Molins Spain to envisage an integrated cement plant at Chatak District-Sylhet) a bordering town of Bangladesh. Since April 2006 the single flight 17 km Long Belt Conveyor (LBC) built by M/S Larsen & Toubro Ltd. (L&T), ECC Division an engineering and construction company of India, is feeding limestone/shale to the Lafarge Surma cement plant. This engineering marvel was created on a turnkey basis with technology support of M/S Aumund France

Jan 1, 2008

By St. Mergentime, K. Zeidler, V. Gall

2001, the New Jersey Transit Authority commissioned the JV Merco-Obayashi with the rehabilitation contract of the approximately 130-year-old, 4,200 ft long, partially brick- lined Bergen North Tunnel. The contract entailed the tunnel enlargement, shotcrete and rock dowels initial support according to the NATM, a waterproofing system, tunnel drainage and a cast-in-place concrete lining. The rock conditions encountered required design adaptations and significant modifications of the initial tunnel support. Flexibility, skill and extensive experience on the Authority’s and Contractor’s side finally lead to a success. This paper describes the operations and design modifications carried out.

Jan 1, 2003

By A. A. El-Midany

Traditionally, the choice amongst different upgrading techniques or in finding the optimum operating conditions for a given upgrading technology depends on whether one is looking at the grade or the recovery of the valuable mineral in the concentrate. In fact, the conclusions are not usually the same. This is because the best technique or optimum operating conditions for the highest grade are not the same as the conditions to achieve the maxi-mum recovery. Therefore, a unique measure that takes into consideration both grade and recovery is urgently needed. Finding such a measure is the objective of this paper. A proposed measure provides a selectivity index in the range of 0 to 1, where 0 is no selectivity and 1 is ideal selectivity. The index can be obtained by plotting the so-called Fuerstenau upgrading curve, which relates the recoveries of the components in products of separation and a running regression applying a one-parameter equation. The measure was applied to assess the selectivity of selective flocculation under different operating conditions when used as a sensitive upgrading technique for ultrafine ground ores. After applying the proposed selectivity measure in the case of the selective flocculation of ultrafine Egyptian iron ore without the addition of cations, it was found that the optimum conditions are pH 11, 1 kg/t sodium silicate and 0.4 kg/t potato starch with a selectivity index of 0.55. With the addition of cations, the optimum conditions were found to be pH 11, 1 kg/t sodium silicate and 2 kg/t potato starch with a selectivity index of 0.65. It should be noted that determining these optimum conditions using the traditional grade or recovery measures was highly ambiguous.

Jan 1, 2008

By R. L. Grayson, J. R. Warneke

Environmental conflict between the public and private sectors, including mining, is highly visible and often based on deeply divergent environmental, social, and economic values. In order to achieve sound public policies by government, scientifically rigorous and objective analyses of mining’s impacts are demanded. Material flows accounting and analysis, linked with other data to generate indicators of environmental, social, and economic impacts of mining activity are means toward providing cogent input into public policy-making on key issues. This paper will present a material flows analysis scheme for the coal industry and recommend derived, objective indicators of coal mining’s impact on society.

Jan 1, 2004

By Daniel Saint Don, Jacques Dumouchel

QIT Madagascar Minerals (QMM)’s heavy mineral sand deposit located near the Village of Fort Dauphin, Madagascar was recently drilled using Boart Longyear Company’s Mini-Sonic drill. Continuous sand core samples were obtained to a depth of up to 30 meters for analysis and compared with the existing drilling data. Results were used as part of a validation process of the resource estimate, based on approximately 1,500 exploration holes drilled to date.

Jan 1, 2005

By H. Kinilakodi

The authors previously had developed a methodology that combines injury and citation measures into an overall mine safety performance evaluation tool, called the Safe Performance Index (SPI). It can be easily adopted by mine operators to monitor trends in their injury and citation experiences as a risk assessment method. In this paper, six normalized safety measures and the SPI are used to evaluate the risk that existed at mines in the two years preceding the occurrence of a fatality. The percentage of mines is given for which the risk was high or where trends of some of the safety measures indicated moderate risk. In 50% of the mines, this mine safety performance tracking method could have been helpful to the companies, state agency, or MSHA in recognizing and addressing emerging problems with actions that may have been able to prevent high-risk conditions, the fatality, and/or other serious injuries. The approach would have given scrutiny to the risk for mines that encompassed 74% of the fatalities during 2007-2010.

Jan 1, 2012

By M. V. T. Da Silva, J. C. Harrison

Eldorado Gold Corporation of Vancouver, B.C. owns and operates three gold mines. The São Bento underground gold mine in Minas Gerais State, Brazil produced 105,907 ounces in1997. The La Colorada and La Trinidad open pit, heap leach mines in Mexico produced over 83,000ounces in 1997. With a deteriorating gold market plaguing the industry throughout 1997 Eldorado had to take critical measures at each mine to enhance gold production while lowering cash operating costs. Each mine had its own unique problems to confront. This case study will discuss three distinct courses of action taken at the three mine sites.

Jan 1, 1999

By M. Imazu, Ö. Aydan

"A new rock classification, Rock Mass Quality Rating (RMQR) proposed by the authors is briefly explained and its application for the design of tunnels and large underground openings support systems is described in this paper. RMQR is an index to evaluate the state of rock mass. The preliminary support design may be based on the concept to prevent structurally controlled failures of rock mass. RMQR can also evaluate the yielding characteristics of rock masses so that it is possible to design a support system to prevent or control the deformation of surrounding rock through the utilization of the proposed rock mass classification and some analytical and numerical techniques.INTRODUCTIONThe first three authors proposed a new rock classification system named Rock Mass Quality Rating (RMQR) (Aydan et al. 2014). RMQR quantifies the rock mass state, and using the classification system together with intrinsic geo-mechanical properties of intact rock, possible geo-mechanical properties of rock masses can be estimated. The instability modes of underground openings can be structurally controlled because of the orientation of discontinuities in rock mass and the in-situ stress induced (Aydan 1989; Aydan et al. 1993, 1996; Aydan and Genis, 2010). The authors (Aydan and Ulusay, 2013; Aydan, 2016) have also tried to apply this system to the design of a tunnel support system. The authors presented initial guidelines for the RMQR classification system earlier (Aydan and Ulusay, 2013).In this paper, the authors provide further guidelines and establish some criteria for support system design that considers loading conditions and types of underground structure according to RMQR. Guidelines are alsos proposed for selecting the proper size of rockbolts, rock anchors, shotcrete, steel ribs and concrete liner. These guidelines are based on past experiences with various underground structures, theoretical understanding and the anticipated behavior of rock mass under given in-situ stress conditions and excavation techniques. The authors also utilized some databases developed for large underground caverns and tunnels excavated in squeezing or rock-bursting ground conditions."

Jan 1, 2016

By J. C. Yingling, R. J. Sweigard, P. W. Conrad, J. M. Ringe, D. H. Graves

Much of the land reclaimed since enactment of the 1977 Surface Mining Control and Reclamation Act is over-compacted. Research has shown that excessive compaction in replaced growing media is detrimental to establishment of trees. If trees are to be grown on reclaimed surface mined sites, something must be done to alleviate this excessive compaction. Dry bulk density and penetration resistance are two soil parameters that can be used to indicate the level of compaction in reclaimed growing media. The University of Kentucky has developed test cells on reclaimed sites at a surface mine in eastern Kentucky to determine the impact of tillage (ripping) on soil compaction and tree survival rate. The ripping methods being evaluated include shallow tillage using conventional farm equipment and deep tillage using a dozer with a ripping arm. The impact of organic soil supplements on soil physical properties and tree survival rates is also being evaluated at the site. The organic soil supplements being evaluated include application of hardwood bark and application of straw and mulch. Each test cell has been planted with various species of trees, and for the first two years, data have been collected at these test cells for soil dry bulk density, penetration depth and resistance, and survival rate of trees. These data are currently being correlated to determine how ripping and the application of organic soil supplements affects the relationship between soil compaction and tree survival rate.

Jan 1, 2002

By Donald R. Lamont

The paper outlines the reasons for and research behind the recent decision to adopt oxygen decompression in the UK. Currently used measures of decompression illness are critically appraised. The paper describes the main precautions to be taken on site to manage the fire risk from the use of oxygen underground. A summary of the initial results from the use of oxygen decompression in the UK is presented.

Jan 1, 2003

By Palmer King

The increased emphasis on environmental protection, together with the exorbitant costs, or in many urban areas the complete unavailability of surface space, has resulted in a burgeoning demand for greater use of underground space. More and more, those considering new or expanded facilities are looking toward the possibility of utilizing underground space for communications installations, for transportation of people, industrial products, water, sewage and energy, and for industrial installations. Happily, this growing demand for use of underground space is accompanied by fast forward strides looking toward more efficient underground excavation techniques. The tunnel boring machine is already here and where ground conditions are suitable for its use it can greatly reduce the cost of underground excavations, savings of one-third or more often being realized. Research is underway involving excavation by use of laser beams, jetting, vibrations, improvement of tunnel boring machines to make possible the excavation of harder rock, and other advanced techniques. The Engineering Foundation estimated in 1973 that tunneling costs can be reduced as much as 30 percent by rapid excavation methods which are expected to be developed through ongoing research programs in the next few years. Your American Society of Civil Engineers reported in 1973 that $60 billion per year, or 15 percent of the gross national product, could be saved if facilities required to support life were located in the subsurface. Studies looking toward improved contracting practices are going on under the sponsorship of the National Academy of Sciences, and Mr. Al Mathews who is heading this program will address you during this session on the status of this project. I myself am a member of Mr. Mathews' study group and, considering the human element involved, it is too early to make predictions as to what can be accomplished in the way of savings in costs of

Jan 1, 1974

By M. J. Zdunczyk

Sand is one of the most common materials on the earth’s surface. It is a naturally occurring material resulting from the physical and chemical breakdown of rocks. The definition of sand varies, as do the number of products made from the material. Sand is generally classified by grain size, however the measurement or scales differ depending on the context in which it is being used. Geologist define sand as particles of rock between .05 and 2 millimeters in diameter. The variability of the mineral composition generally dictates which sand can be used for different industrial purposes. For example, sand used for Portland cement concrete and asphaltic concrete mixtures can be very different in physical and chemical composition than sand used in the making of fiberglass. In this paper, construction uses of silica sand, which consists almost entirely of the mineral quartz (SiO2), will be discussed and analyzed.

Jan 1, 2001