Search Documents

By Eric Lutz

"Great effort has been expended for more than 40 years to improve the workplace safety and health of surface and underground miners across the United States. When looking at the past decade, withstanding the 2010, Upper Big Branch (UBB) disaster that took the lives of 29 miners, this effort has resulted in a generally decreasing trend from 57 fatalities (22 coal; 35 metal/non-metal) in 2005, to 45 (16 coal; 29 m/ nm) in 2014. Through August of this year, there have been 23 mining-related deaths (eight coal; 15 m/nm). These results reflect continued diligence and perseverance on the part of miners that stay true to our legacy; and demonstrate significant investments from mine-site leadership, mining corporations, and state and federal regulators. However, over the past five years there have been an average of 32 fatalities per year, with a low of 36 (2011 and 2012) to a high of 45 (2014). If we know that there will be somewhere between 30 and 50 mining related deaths next year, which of us will volunteer to be counted as one of the numbered? Clearly, we all agree that one fatality is too many; and as evidenced by changes following UBB, deaths in any sector are deaths reflective of all mining across all sectors.The impact of each miner death touches us all. Miner’s deaths are felt deeply by family and friends, most significantly the children; their communities in which they served, supported, and worshiped; and by society that has lost a hardworking, dependable contributor. Further, to take a slightly cynical, but realistic view, miner fatality events impact the financial vitality of mining and contracting companies and broadly diminish investor confidence. Just as important, these events significantly impact our communities and result in negative public perceptions, which ultimately drive regulatory policy and related compliance pressures. This resulting pressure forces operations to broadly address safety and health gaps in very specific ways (i.e., see U.S. Mine Safety and Health Administration (MSHA) regulations regarding lids for trash cans) minimizing a mine site’s opportunities for operational flexibility. To break this cycle that is the operational reality, mining companies are focusing tremendous efforts on fatality prevention and specifically on dedicated investment to prevent multiple fatality events."

Jan 1, 2015

By Terence G. McCusker, Bruno Dietl

The only previous attempt to use a tunnel boring machine in the rock formations encountered in New York City was unsuccessful. However, technology has been developed since then which made a new attempt a practical proposition. Nine thousand feet each of 8'6" and 11'0" diameter tunnels were driven in Manhattan schist using Jarva TBM's together with 1100 ft. of the smaller diameter driven conventionally in Inwood marble and earth. (1) The selection of tunneling method was largely based on the need to avoid community reaction and hazardous tunneling conditions where the larger diameter tunnel passed beneath residential structures in poor condition in seamy and blocky rock. Experimentation with cutters and cutter mountings indicate that good cutter life and ease of change are available. It was found practical to use unusually large muck cars for an efficient muck disposal system. Conventional tunneling was successfully executed beneath a subway station whose invert was less than seven feet above the crown of the tunnel. Attempts at chemical consolidation and dewatering were unsuccessful in the earth section which was completed under compressed air.

Jan 1, 1974

By Thomas H. Koenning, William E. Bruce

Determination of the state of a mine fire is an important function during firefighting and during rescue and recovery operations. It is imperative that an accurate, up-to-date assessment of fire conditions be available for persons directing such activities in order to avoid unacceptable risk to mine rescue teas and/or fire fighters. Many indicators which consist of ratios of the concentrations of fire gases have been developed over the years for determining the state of a mine fire. Results from numerous gas sample analyses are necessary for determining the trend of the fire. Some indicators are preferred because the influence of sample dilution, a frequent problem, is said to be eliminated. Definitions and examples of indicator6 found to be useful in diagnosing recent western U. S. coal mine fires are presented. Mine gas explosibility is an important subject also requiring rapid assessment. Example explosibility calculations are presented applying one widely used method. Establishing limits for withdrawal of personnel are discussed.

Jan 1, 1987

By Ravi Ray, Kostas Kaklis, Zach Agioutantis

"Modern underground mining is becoming more complex and geotechnically challenging. The engineer uses numerical, analytical, and data-driven methods (empirical and/or experimental) or their combination to overcome these challenges. Each method has its advantages and disadvantages. Nevertheless, given the amount of innovation and experience involved in developing each of these techniques, it will be prudent to use all their benefits rather than favoring one technique over the other. Pillars are the most important support element in an underground mine. A holistic geo-mechanical solution needs to be determined to design mine pillars using a proper sequence and exact mix of the three methods. A combination of these methods, in sync, can encompass the several advantages of the three methods while eliminating their disadvantages. This paper presents a conceptual three-tier solution to the pillar design problem, to improve its design pedigree, using a proper combination of numerical, analytical, and data-driven methods. At the focus of this proposed method lies the Ground Reaction Curve (GRC) concept.INTRODUCTIONAlthough the stability analysis of underground excavations is a challenging problem, its understanding has improved tremendously over recent years through the use of improved tools and techniques. The trial and error method was replaced with more scientific methods like the empirical and analytical methods that are still in use today. Empirical methods were developed based on large data sets obtained from experiments and observations (e.g., coal pillar strength equations). Analytical methods were developed based on mechanical understanding of stability (e.g., safety factor for vertical pillar loading, Convergence Confinement Method). Improvement in computing power and numerical techniques led to the development of several numerical methods (e.g., finite difference, finite element) suitable for geo-mechanical analysis.Each of these methods have certain advantages and limitations. Nevertheless, the user is often puzzled over the proper method selection and over the proper sequence of using them. This exercise becomes more challenging when different methods are combined, where, for example, one has to estimate the pillar strength based on empirical equations (e.g., Mark-Bieniawski coal pillar strength equation), determine the factor of safety based on an analytical approach (e.g., tributary area load divided by pillar strength), and analyze pillar-strata interactions using numerical analysis (see Esterhuizen, Mark, and Murphy, 2010b).Challenges increase when current pillar design methods are designed as passive structures to balance the fixed dead weight of the overburden. This classic suspension design approach does not recognize the self-stabilizing capacity of the overburden (Frith and Reed, 2018). A practical solution to address these issues is the use of numerical analysis. However, one should always keep in mind that the numerical modelling approach may have certain practical limitations."

Jan 1, 2019

By Chaoxun Zhao, Daniel Tao, Craig Blue, Narendra B. Dahotre, Rick Honaker, Bhupendra K. Parekh, Hongyang Han

Equipment wear and corrosion have significant adverse impacts on the operating cost and efficiency of mineral processing plants. In this project advanced surface enhancement technologies are being investigated to decrease the wear and corrosion rate of metal surface. Enhanced metal surfaces are achieved through surface conversion, enrichment, and coating by use of advanced High-Density Infrared (HDI) and other technologies. Studies have been done to determine the effects of process parameters on surface properties and identify optimum conditions. The microstructure of the enhanced metal surfaces was characterized by SEM, EDS, and microindentation. Laboratory wear testing was carried out to investigate the wear performance and the viable coating candidate was determined.

Jan 1, 2005

By R. G. Graber

Field testing of GPS mining applications has confirmed the technical and operational viability of GPS for precise, centimeter-level positioning in harsh taconite environments. GPS hardware has provided consistent availability exceeding 90%, with precision in certain applications of ± 0.07 foot at 95% confidence levels. Despite these technical successes though, challenges persist in achieving effective GPS integration. These challenges include the acceptance of new job tasks by mine personnel, the capacity of typical mine data communications infrastructure and the need to design GPS interfaces for new mining equipment.

Jan 1, 1998

By George G. Reed

Approximately 200 samples of iron ores and other iron- bearing materials have been tested for amenability to treatment by the R-N process in bench scale laboratory work. Twelve large lots, ranging in size from 900 net tons to 18,500 net tons, but generally 3,000 to 4,000 tons each, have been processed in the R-N demonstration plant. The ores tested in the demonstration plant ranged from 27 to 70 percent iron content and gave excellent results. (1) The demonstration plant has a nominal daily capacity of 50 tons of high quality iron briquettes and has now operated for over five years. A continuing program of process improvement is carried on between demonstration on potential licenses ores. An important development is the complete elimination of any secondary products which, in the past (2,3,4,5), resulted from treatment of certain low-grade ores.

Jan 1, 1960

By S. K. Ghosh

This paper discusses how the information on ash composition, ash-fusion temperatures, and ash-slag viscosity can be utilized to predict slagging and fouling potentials of a particular coal. A review of several empirical parameters which are commonly in use for determining such potentials is given. Also, some guideline values for interpreting the relative propensity of slagging and fouling of various types of coal are provided.

Jan 1, 1983

By Stephen W. Lambert

One of the primary interests of the United States Department of Energy's Mine Planning Division is to fully develop avenues of technical research which potentially offer positive effects on coal mine productivity. One such area of research involves the removal of methane gas from unmined portions of coalbeds through vertical wells drilled from surface locations. As coalbed methane content is reduced, less gas is available for flow into the mine, and consequently ventilation requirements are decreased and/or coal extraction rates increase. Another attractive aspect of the vertical borehole drainage method is that it presents an opportunity to recover and utilize significant quantities of methane gas, which would otherwise be wasted to the atmosphere. The viability of removing gas from the Mary Lee coalbed using stimulated vertical boreholes was first suggested by Elder and Deul as a result of a United States Bureau of Mines' drilling project conducted from 1971 to 1974 (4). Other United States Bureau of Mines' studies forecasted that degasification would eventually be necessary in the Mary Lee coalbed because most new or expanding mine development would take place at depths exceeding 1 000 feet (305 meters), where the methane problem would be severe (3) (13). In 1975 a large-scaled drilling program was designed in order to supply industry's anticipated need for a degasification technology in the Warrior coal basin, Alabama. The results of this government/industry sponsored effort were to be specifically applicable to the Mary Lee coalbed, the most extensive and economically important deep minable coal present in the area. Major technical objectives of this program are twofold: (1) to measure the effects of various well completion designs, particularly hydraulic stimulation, on mining and (2) to determine the effects of well spacing on gas drainage rates. A cooperative agreement was established with United States Steel Corporation in late 1975 and field work began shortly thereafter in the proximity of a newly developing mine near Oak Grove, Alabama. Government responsibility for this program was transferred from the United States Bureau of Mines to the United States Department of Energy in October 1977. To date, as a result of this program, twenty-one wells have been completed into the Mary Lee coalbed at the Oak Grove site. Seventeen of these wells were drilled on an experimental grid pattern located two miles from the active mine. These grid wells are primarily being used to generate data necessary to determine the effects of well spacing on gas drainage rates and will also provide a large amount of information regarding the long-term effects of degasification on mining. The four remaining wells (designated Ton through TW4) were placed near the mine so that the full effects of completion could be studied within the short time required for underground interception. Results gathered from the first two test wells (TW1 and TW2) have been reported in detail (10) and indicated that several improvements were necessary to increase gas drainage rates. Hydraulic stimulation was one of the most important aspects of well design that required improvement. Nitrogen-charged foam stimulation treatment was used at TW3 and TW4 instead of the gelled-fluid type stimulation used at the first two near-mine test wells.

Jan 1, 1980

By Robert L. Randall

The mineral industries have a continuing need for market forecasting and analysis for a variety of purposes, among which are organization and control of the sales effort, financial and corporate planning, and evaluation of the anticipated revenue from investment in proposed projects. For anything beyond the simplest extrapolation, some kind of economic reasoning or analysis is called for, which may or may not be incorporated into a formal or quantitative model. The principles described here apply to most of the commercially significant minerals and metals. The examples are drawn largely from the copper market, as it is the one with which I have the most practical experience. Practical forecasting is the process of analysis and synthesis from three categories of knowledge: facts and statistics, theory, and practical knowledge and informed opinion. Although many attempts have been made to build forecasts on only one of these three pillars, none has been successful as an operating procedure because of the lack of balance. There are no facts about the future-only about the present and the past. Facts can illuminate the future, but the future can be described only in terms of probability or more or less likely states of affairs-not as a continuous extension of the past and present. Likewise, theory, although useful as an organizing discipline and for providing a methodology of analysis, is inadequate for the complexities of reality. This is especially so when there is feedback between plans and forecasts to produce a new outcome and when there are significant elements of unpredictable free will, such as presidential jawboning or foreign policy considerations. Such elements are difficult to accommodate in neat theories, although they must certainly be reflected in the forecasts. Pure opinion frequently suffers from both a lack of-disciplined reasoning and the presence of biases or self-interest. While the future is unknown, it tends to cast its shadow before it; hence, forecasting is the art and science of positioning oneself so that the shadow becomes visible to the forecaster.

Jan 1, 1979

By T. H. Eyde

Worldwide production of natural zeolites during 2001 was estimated to be about 3.5 Mt (3.85million st). Construction and agriculture continued to be the major consumers. Estimated production in North America during 2001, including the United States, Canada and Mexico, was about 40 kt (44,000 st). In the United States and Canada, the zeolitic tuffs are ground, extruded or modified for use as adsorbents, desiccants, ion-exchange media and carriers. In Mexico and the rest of the world, the zeolitic tuffs are cut into dimension stone that is used in construction. Zeolitic tuffs are usually composed of the minerals clinoptilolite, mordenite or both. They occur in a variety of colors and are easy to cut and shape. And they have low thermal conductivity. This construction application is classified with dimension stone rather than with chemical and agricultural uses.

Jan 1, 2002

By M. Pope

By 1950, packaged oil and gas fired boilers were on the market for capacities up to 30,000 lbs./hr. By 1962, capacities were up to 100,000 lbs./hr. and even higher when separate heat traps (economizers and air preheaters) were attached to the boiler packages. During this period, complete packaged coal fired boilers were developed into the 10-15,000 lbs./hr. range. Oil and gas fired plant designs became very compact, "basementless", and far: less costly than the coal fired plants of any capacity. Coal fired plants remained large and expensive, required field erection of boilers and required basements. With the spectacular strides made in automation, oil and gas plants became far less costly to operate, requiring only the part-time attendance of a single operator. Some advances were made in coal fired plants, but not to the degree attained by the fluid fuel competition.

Jan 1, 1965

By Donald J. Reining

The California Surface Mining and Reclamation Act (SMARA) is the nation's first legislation establishing a statewide mineral resource policy governing mining activities that recognizes regional needs and retains local autonomy. The Southern California Rock Products Association supported this proposed legislation. It was through our efforts that SMARA was passed in 1975. The local planning and zoning processes, which are so critical to the mining industry, have been significantly improved with implementation of SMARA. Recognition of the importance of the mining industry is now being developed by the State Mining and Geology Board and the California Division of Mines and Geology (CDMG).

Jan 1, 1984

By E. Rigopoulos

Mining disturbs the environment, even when the ores or the minerals extracted are non-toxic. Silver & Baryte Ores Mining Co S.A (S&B) is committed to minimizing the environmental impacts of its mining activities, by implementing an integrated rehabilitation program wherever it operates. The paper discusses the principles for mining-disturbed land restoration activities on Milos Island for a successful outcome.

Jan 1, 2003

By Merwin Bernstein

Peru has been an important source of metals since Aug. 29, 1533. On that day Francisco Pizarro took charge of the 24 t (772,000 oz) of gold and silver that constituted Atahualpa’s ransom. At today’s prices, the value of that booty ranges between $100 and $150 million, depending on the proportion of gold to silver. Since then, Peru’s silver and gold production has been legendary. Current mine production Most of Peru’s metals are mined from the Andes Mountains and its foot-hills. The Andes run the length of the country parallel to the Pacific coastline from Ecuador to Chile, a distance of nearly 3000 km (I 875 miles). They are about 300 km (187 miles) wide and much of the range is more than 3000 m (9900 ft) in elevation. High plateaus (altiplanos) occupy a large part of the range. Both flanks are rutted by large valleys and canyons. Many of these peaks are prodigious. which make road building expensive and adds to the cost of mining.

Jan 1, 1993

By P. L. Dunn, G. T. Adel, E. B. Cruz

Automatic control of fine-coal cleaning circuits has traditionally been limited by a lack of adequate sensors. Although several nuclear-based analyzers are available, none have seen widespread acceptance. In this investigation, image analysis is used for the on-line determination of ash contents in fine-coal slurries. The ash content of a flotation tailings stream is correlated to the mean gray level of the slurry. Based on a 90% prediction interval, an analysis of sensor performance indicates an accuracy of 73[±] 4% ash over a range of from 65% to 90% ash. While the results are comparable, the video-based system costs only a fraction of what a nuclear-based analyzer costs. The sensor is now installed at the Middle Fork preparation plant, which is owned by Pittston Coal Co.

Jan 1, 1999

By M. D. Loy

In addition to products available from private vendors, many useful programs are developed at universities - in fact, many of these programs led the way to commercial development. Other projects are assigned to consultants with backgrounds in system design and mining. Both types of development have led to programs that can be acquired for the cost of a tape or disk. This paper highlights several underground mining packages. These programs consist of: ? USBM model-developed by the United States Bureau of nines. ? PSU model-developed by Pennsylvania State University. ? VPI model-developed by Virginia Polytechnical Institute and State University. ? NUS model-developed by NUS Corp.

Jan 1, 1987

By Vanessa M. Torres

Diagnostic leaching tests provide a good indication of gold deportation in its various occurrence phases. With the results of these tests, possible flowsheets for difficult ore treatment can be established for further evaluation and plant operation can be optimized. The use of this technique can be extended, including heap leach evaluation and complex copper-gold ores. The results on the use of diagnostic leaching tests in gold ores from Companhia Vale do Rio Doce (CVRD) are presented and discussed, as well as the methodology to select steps and interpret results used at CVRD Technology Center (Sutec).

Jan 1, 1998

By Y. H. Zhan

In beneficiation of phosphate ores it is common to use screening to produce the coarse "pebble" concentrate, and flotation to process the -1+0.1 mm size fraction. The -0.1 mm desliming product is treated as tailings. A new partially hydrophobic flocculant, P(MAAA) latex was developed to enhance flotation recovery of fine apatite particles through selective flocculation.

Jan 1, 2002

By Tim Wolf, Barry Fink

Mine site managers reported occurrences of locking assembly bolt failures on the Enlow Fork Coal Mine's slope belt conveyor. The observations were made after a number of years of operation and raised questions as to the status of the assemblies in operation. These questions prompted a detailed review of the situation by independent consultants. Using operational history of the conveyor and confirmation of belt loads by static and dynamic methods, a locking assembly fatigue curve was created to suggest expected service life. From this work, suggestions were made to modify the pulley assemblies for extended service life.

Jan 1, 2002