Search Documents

By E. Morrice, R. D. Smith

Thermal expansion and electrical resistance measurements were made on cerium metal from 4° to 300° K. The apparatus developed , including a specimen holder and a cryostat system , are described along with the experimental techniques used in obtaining the measurements . The total linear thermal expansion Data at of 99.83 weight - percent cerium metal between 4 ° K and room temperature was 4.24 percent . The resistivity at 4° K was 7.0 x 10-6 ohm- centimeter . 4° K indicate a fundamental relationship between residual resistivity and purity of cerium metal . The effects of annealing and repeated thermal cycling on resistivity were determined .

Jan 1, 1964

By W. Collingwood

As openpit mines continue to grow deeper and productivity continues to increase, the management of respirable dust and noxious gases can become a challenge. The natural wind flow in openpit mines is often recirculatory. This recirculation traps dust and gases in deep openpit mines. This problem is particularly acute in high-latitude openpit mines, due to a phenomenon known as atmospheric inversion. In the winter, arctic and subarctic regions experience short days and long nights. This deficit of solar radiation creates a situation in which cold, still air accumulates near the bottom of the pit. In openpit mines, this can result in unhealthy accumulations of gases and other contaminants. In this study, the natural wind flow patterns in and around openpit mines were investigated using a computational fluid dynamics (CfD) program. Two-dimensional models were created for a variety of pit geometries. The effect of depth, slope angle and wind speed on the recirculation pattern in the pit was examined.

Jan 1, 2012

By Eric E. Cather

A mineral survey of the Fisher Gulch RARE II area (A5299), Trinity County, California was conducted by the U.S. Bureau of Mines and U.S. Geological Survey. The Bureau of Mines was responsible for detailed examination of mines, prospects, and mineralized zones; the Geological Survey conducted geological, geochemical, and geophysical studies of the area. The area is underlain by the Salmon Hornblende Schist. Tonalite stocks 1.5 mi (2.8 km) to the east and northeast of the area intrude the schist and are closely associated with the nearby nines (Cox, 1967). The mines have quartz veins containing sulfides and gold in shears trending east to north past in the schist and tonalite (Hotz, 1972). Strewn and terrace gravel s occupy most of the drainages, many have yielded substantial quantities of gold.

Jan 1, 1981

By P D. "Takis" Katsabanis

The phenomenon of sympathetic detonations in blastholes is investigated by comparing experimental observations and numerical modelling results. Numerical modelling using the TDL computer code and Forest Fire decomposition rates for commercial explosives has shown the importance of blasthole diameter, impedance of the stemming and host rock. Comparison with experimental observations has also shown that sympathetic detonations cannot always be treated as shock to detonation transition. Examination of previous results which have been obtained from calibrated low amplitude shock experiments reveal that there is an ignition threshold prior to the detonation threshold. The difference between the two thresholds is more pronounced in the case of air bubble sensitized products. The ignition threshold can be very important under the confinement provided by the blasthole and the conditions of application. It also correlates well with the pressures expected at the gap distances of interest in the practical application. It is suggested that critical energies are used as the criterion for cross initiation in blastholes. Practical suggestions based on the numerical calculations and experiments based on these calculations are also given and discussed.

Jan 1, 1991

By J. A. de Carvalho Junior

This paper analyses the impact of the uncertainty associated with the input parameters in a mine planning optimization model. A real example was considered to aid in the building of a mathematical model that represents the coal production process with reference to the mining, processing, and marketing of coal. This model was optimized using the linear programming concept whereby the best solution was perturbed by the stochastic behaviuor of one of the main parameters involved in the production process. The analysis of the results obtained permitted an evaluation of the risk associated with the best solution due to the uncertainty in the input parameters.

Jan 1, 2012

By Mike Perkins

The Summitville Au-Ag-Cu district in the southeastern part of the San Juan volcanic field has been a major gold producer in Colorado. Mineralization is hosted by the composite South Mountain quartz latite porphyry volcanic dome, which is believed to have been localized by the intersection of the northwest margin of the Platoro-Summitville caldera complex and the northwest-trending Platoro fracture zone. K-Ar age dates indicate that alteration and mineralization were nearly contemporaneous with emplacement of the dome at 23-20 m.y. ago, 6-7 m.y. after collapse of the Platoroo-Summitville caldera complex. The dome consists of at least four major phases including strongly altered quartz latite porphyry; a late-mineral, coarse-grained sanidine quartz latite porphyry; and postmineral quartz latite dikes. The dome was emplaced into intracaldera rhyodacite and andesite. Gold-silver-copper mineralization is concentrated near the top of the dome and is associated with pods, pipes and steeply dipping tabular zones of silicification and advanced argillic alteration. Alteration is zoned outwards from the center of mineralization through argillically and propylitically altered rocks, and is largely confined to the area of the dome. Trace element geochemical patterns for the deposit indicate a central zone of anomalous As-Au-Pb-Ag and low Mn within an exterior zone of anomalous Ag-Au-Pb-Hg and high Mn. The chief ore mineral is native gold which is associated with goethitic iron oxide in the oxide zone. In the sulfide zone, native gold is associated with copper sulfide-sulfosalt mineralization. A genetic model for the Summitville deposit is based on recent models of modern geothermal systems, with which it shows similarities in alteration, ore mineralogy, zoning, and structural patterns.

Jan 1, 2013

By S. H. Ash

THE INUNDATION of anthracite reserves in the Eastern Middle field of Pennsylvania affects the life of the anthracite industry in this field; it also influences the economic status of people, communities, and industries that depend wholly or in part upon anthracite for their livelihood. The trends of production and of employment in the anthracite-mining industry in this field are downward, and they probably will continue in this direction. The reserves have been depleted to the extent that the end of the active life of the industry as a. major economic factor is approaching. By removing the water in those pools where it can be done economically, the future of this industry may be extended somewhat.

Jan 1, 1950

By H. M. Kim, J. Rutqvist, D. W. Ryu

"Demand of high pressurized gas storage in underground rock caverns is increasing. Compressed natural gas (CNG) and compressed air energy storage (CAES) are one of the promising examples after since lined rock cavern (LRC) concept has been verified through in-situ pilot tests. Two key essential concerns of high pressured gas storage in underground rock caverns are mechanical stability of the cavern against high inner storage pressure and the risk of gas leakage from the caverns.In this study, we introduce our results of numerical simulations so as to investigate the potential of monitoring for gas leakage at a pilot facility for CAES in underground LRCs. The pilot facility was constructed at a comparatively shallow depth of 100 m, compared to the previous cases with several hundreds of meters, aiming at validating the feasibility of the LRC storage concept in which inner sealing liners, consisting of steel plate and concrete linings, are installed inside the excavated rock caverns (KIGAM, 2011). Compressed air may leak through either initial defects of inner containment liners such as imperfect welding regions and in-situ construction joints of the liners, or through structurally damaged points of the liners during the CAES operation where compression and decompression of the caverns are necessarily repeated and their structural robustness can be deteriorated.For this perspective, we carried out a coupled thermodynamic and geomechanical deformation analysis using TOUGH-FLAC simulator, and investigated the effectiveness of strain monitoring method in detecting mechanical failure of liners which may provide major pathways of air leakage. We therefore used an equivalent continuum model to relate the localized tangential strain to fracture permeability changes, which was developed in our early work (Rutqvist et al, 2012). In detecting and characterizing the leakage location, we tested a cross correlation technique using the synthetic pressure responses monitored in case of the failure of the inner liners. From the investigations, we showed that tangential strain, rather than radial, monitoring especially at the inner face of the sealing liners can be more effective in detecting the mechanical failure of the liners.In localizing the leakage point, we noted that the interface between the inner liners and surrounding rock may not be perfectly bonded so as to increase permeability through which any leaking air pressure may migrate more dominantly. We also demonstrated that the cross correlation of the time histories of pressure measurement especially at these interfaces can be useful in identifying the leakage point. These results may provide useful information in overall design of monitoring and alarming system of our upcoming CAES pilot facilities."

Jan 1, 2015

By Jonathan K. Hrica, CASSANDRA L. HOEBBEL, Jennica L. Bellanca

Accidents involving powered haulage and mobile equipment such as haul trucks often account for the greatest number of fatalities in the mining industry each year. Despite previous analyses that have identified root causes and other contributing factors, there is still a need to better understand the events leading up to these types of accidents, what lessons may be learned, and what strategies can be employed to prevent fatal accidents from occurring. This study examines Naturalistic Decision Making (NDM) using the critical decision method (CDM). The CDM is a retrospective interview approach used to explore timelimited, high-stakes, decision-making. In this study the CDM is used to obtain more information about what happens prior to, during, and after a potentially fatal situation such as a near-miss event, loss of control, or minor accident involving equipment damage. Researchers captured firsthand accounts from 21 haul truck operators involved in near-miss events from mine sites of various sizes and commodities throughout the United States. These accounts provide rich and detailed narratives from the perspective of haul truck operators themselves and reveal insights into what decisions haul truck operators make, what sensory cues they perceive, and what strategies they employ during challenging and non-routine situations. Decision-related themes that emerged from the data are presented and discussed. These results, along with potential solutions offered by study participants, can help to inform future research, raise awareness about hidden hazards, and build more creative interventions and realistic training scenarios for use by the industry to address haul truck safety issues.

Feb 1, 2024

By M. Dobbins

The advent of the more efficient and effective rare-earth roll (RER) separator in the early 1980s began a new era of dry magnetic separation. The RER units quickly became the separator of choice within the materials processing industry. Though RER separators are now commonplace throughout the world, only modest advancements have been made to the original design. This paper details recent, more significant, rare-earth magnetic separation developments. These developments maintain the best features of existing technology while minimizing shortcomings. The discussion includes discerning features that aid in better metallurgical performance. Also discussed are improved mechanical aspects that allow for both easier operation and maintenance. Performance details from various test programs are included.

Jan 1, 2010

By Larry M. Southwick, Phillip J. Mackey, A. E. (Bert) Wraith, Albert Pelletier

In 1881, the first commercial pneumatic Bessemer-type converter treating copper matte was successfully introduced by Pierre Manhes at the Eguilles copper plant near Vedène in France. This development followed over a year of testing on a smaller scale at a foundry in Vedène, during which the vertical tuyeres of the conventional Bessemer converter had been successfully replaced by horizontal tuyeres in an effort to avoid the freezing of copper which had occurred in the bottom of the vessel having vertical tuyeres. The Manhes Converter, as it became known, was the first successful large-scale adaptation of the Bessemer concept of using compressed air blown into a melt for metal refining and treatment. Within a few years, Manhes Converters utilizing horizontal tuyeres in either the original type of vertical converter, or a later and more enduring horizontal barrel converter, were in operation at over a dozen copper smelters around the world. It was this process that Messrs Peirce and Smith essentially improved with the introduction of the larger converter which bears their name and the development celebrated at this Symposium. The present paper briefly traces the original development by Pierre Manhes in the early 1880s and which set the stage for the later Peirce-Smith adaptation. The paper observes that the original development by Manhes was in part driven by the need to reduce coal (energy) consumption and hence the production cost in order for Eguilles to remain competitive with the larger plants in Swansea, Wales, where a ready supply of cheap coal helped keep smelter treatment terms of the day low. These themes are eerily resonant of today where booming copper production in China has impacted the industry, and also where energy consumption, closely linked to today’s more familiar theme of ‘climate change’ remains an important challenge currently confronting the entire industry. The paper concludes with comments on these seemingly parallel situations today and offers some thoughts for the future.

Jan 1, 2009

This report presents depth and producing rate statistics pertaining to oil reservoirs (or fields) in each of the 14 States that produced more than 20 million bbl of oil during 1965. The combined oil production was about 2.6 billion bbl, or 96 pct of the U.S. total. Data are presented for each of the 14 States, each Texas Railroad Commission district, and four geographical areas of Louisiana. About 8 pct of the total oil produced in the 14 States was from depths of lees than 2,000 ft, 24 pct from 2,000 to 4,000 ft, 22 pct from 4,000 to 6,000 ft, 16 pct from 6,000 to 8,000 ft, and 30 pct from 8,000 ft and deeper. The average production per well in the 14 States ranged from 4.4 bopd for wells less than 2,000 ft deep to 57.6 bopd for wells 8,000 it and deeper. Data indicate that 9.5 pct of the 460,968 wells produced more than 1.2 billion bbl or 46.6 pct of the total oil. Oil production from reservoirs (or fields) not undergoing stimulative recovery operations, such as steam, air, gas, or water injection, wee about 1.1 billion bbl or 42.1 pct of the total.

Jan 1, 1967

By John C. Holtz

"The Federal Bureau of Mines serves the mining industry by approving equipment that is designed to prevent explosion, fire, shock, or toxic hazards in mines when such equipment is used and maintained in a proper manner, through research, consultation, testing, and inspection, the Bureau studies machinery and component parts submitted by manufacturers and others. Before receiving the Bureau's approval as permissible for safe use in mines, equipment must pass exacting tests and must meet strict requirements established through research and experience and listed in the Bureau's various permissibility schedules. An important phase of the Bureau's research is the testing of diesel engines.Mobile diesel-powered equipment can be used safely in underground noncoal mines and tunnels when mechanical ventilation is provided to dilute and remove the exhaust gas and to replenish oxygen in the underground atmosphere. Safe ventilation is determined by suitable tests of each engine used in a diesel machine. This ventilation cannot be predicted safely, accurately, and economically from any general empirical relationship.In determining safe ventilation, the quantities of carbon dioxide, carbon monoxide, and oxides of nitrogen generated by a diesel engine must be ascertained. These quantities are related to the displacement of the engine, its speed of operation, the design of the combustion chamber, and the fuel:air ratio needed to produce useful power. At overrich fuel:air ratios, all diesel engines generate excessive quantities of toxic carbon monoxide and smoke. The results of engine tests are used to determine a maximum fuel-injection rate at or below which carbon monoxide can be controlled by a reasonable ventilation and smoke is essentially eliminated. Toxic oxides of nitrogen are related to fuel:air ratio and the design of the combustion chamber. Their concentration in the exhaust cannot be controlled by engine adjustments, and each engine appears to have individual characteristics concerning formation of these oxides. Production of oxides of nitrogen frequently is the most important factor in determining safe ventilation."

Oct 1, 1959

By Michael Rieber

A new mode of coal transportation based on the principles of pneumatic conveying has been recently, proposed by Soo, et al. [5]. Pneumatic transport is not a novel concept and commercial experience with pneumatic pipelines for short haul distances is plentiful. The list of applications is long and includes transporting ores, chemicals and pharmaceutical products, agricultural products, and domestic and industrial wastes. The study by Soo, et al. [5] updated an earlier one [l0] and presented the most recent economic evaluation of pneumatic transportation of coal. Their preliminary study concluded that there are immediate advantages for short-distance transport (less than 100 miles) and that it is both technologically and economically feasible. That study also concludes that pneumatic transport has a higher potential and more promising profitability in long-distance applications than rail if new track and roadbed must be built. Some of the advantages of long and short distance pneumatic pipeline transport of coal compared to rail and slurry transport are: 1) Replacement of diesel fuel consumed by unit trains, as the pipeline can be powered by coal-generated electricity; 2) Reduction of the skilled-labor costs required for upgrading and maintaining railroads; 3) Elimination of signaling, rerouting and overpass costs due to increased rail traffic on' mainline trackage;

Jan 1, 1977

By Robert F. Chaiken

More than 500 fires are now burning in abandoned coal waste banks and coal deposits in the United States. Once established, such fires can burn for decades, and extinguishing them by conventional methods such as surface sealing to exclude air, excavation to remove fuel, or flushing to cool the fire zone is usually difficult and always expensive. Burnout Control, a technique developed by the Bureau of Mines for the control of abandoned fires, involves the accelerated combustion of coal in place with total management of the heat and fumes produced. A burning waste bank or mine is placed under negative pressure relative to the atmosphere, and heat and combustion products are drawn from the combustion zone through an exhaust ventilation system. Heat produced appears as sensible heat in the exhaust, at temperatures as high as 1,000° C (1,832° F), and can be recovered for the production of steam, hot water, process heat, or electricity. The Bureau's first field demonstration of Burnout Control was at Calamity Hollow in Allegheny County, PA (near Pittsburgh). Calamity Hollow was the site of an underground mine in the 1900's and was surface mined in the 1940's. In the winter of 1961-62, a fire of undetermined origin was discovered in the exposed coal. In 1963, the Bureau constructed a trench barrier around the fire and a surface seal over the affected area. The fire was isolated, but not completely extinguished. In 1979, when the Bureau began work on the Calamity Hollow Mine Fire Project, to demonstrate controlled burnout, the fire was still smoldering on the hot side of the trench barrier. The project, which was begun in December 1979 and ended in July 1982, consisted of the design, construction, operation, and subsequent dismantling of a Burnout Control ventilation system. This report is the fourth in a five-part series that describes the Calamity Hollow Mine Fire Project. The first report, part 1, describes the design and construction of the field installation. Part 2 will present the results of a continuous 4-month burnout operation. (Because part 2 involves the analysis of a substantial body of data, it will not be published until after publication of parts 3, 4, and 5). Part 3 describes the instrumentation used to control and monitor the progress of the burnout operation. This part (part 4) and part 5 both deal with the closeout phase of the field demonstration. The quenching of the fire is described in this report, and part 5 will describe the final excavation and backfilling of the heated zones. The reports in this series document the Calamity Hollow controlled burnout demonstration, which showed that (1) controlled in situ combustion is a feasible method for controlling underground fires in abandoned mines, (2) the resultant thermal exhaust output is sufficient for energy utilization, and (3) water injection with fume exhaustion is a potentially effective method for cooling large underground fire zones. Further trials of both Burnout Control and water injection with fume exhaustion are planned.

Jan 1, 1984

By Michael J. Lehnen

Slurry diaphragm walls are commonly used as both temporary excavation support walls, and permanent structural walls, for circular shafts and long rectangular structures (such as underground subway stations); however, they are not commonly used for more compact rectangular or square shafts. In these instances, a second wall is typically cast inside the slurry walls to form the permanent structure. This paper discusses the approach used on the Silicon Valley Rapid Transit Project in California to analyze these compact rectangular types of structures for static and seismic loading, and to determine whether or not slurry walls can be confidently used as both the temporary and permanent walls for two tunnel ventilation shafts.

By Chee Theng

"What would you do if you are an industry leader and disruptive technology threatens to overturn your business model? Although bearings and seals are in little danger of being displaced in the near future, one company is taking no chances in an age of digital disruption.“For SKF, digital transformation and the Industrial Internet of Things (IIoT) make this time right now arguably the most exciting time in our 100-plus years of history,” John Schmidt, president of SKF USA Inc., said during the SKF Technical Press Day in Philadelphia, PA.The company is not merely integrating digital technologies into its products and services but is taking a forward-looking, strategic approach. “To be successful, legacy companies have to undertake a process called digital transformation. It’s not just an IT initiative but is really about upgrading the strategic thinking,” explained Michael D’Argenio, vice president of digital transformation and customer experience at SKF Americas.Learning from those who went beforeD’Argenio cited the examples of two companies that saw entirely different outcomes in the face of digital disruption. The well-known case is that of Kodak, one of the storied brands in history, whose business was disrupted by the advent of digital photography. Although it invented digital photography, Kodak decided to box it up and put it on the shelf because it was scared of disrupting its business in photographic fim. Instead, it was disastrously disrupted from the outside.Less well known is the case of Encyclopedia Brittanica Inc., publisher of the longest-running English-language, general-knowledge encyclopedia in the world. Sales peaked at 120,000 sets in 1990, plunging to 8,000 sets in 2012. In 20 short years, it saw not one but two massive digital disruptions. The first was in 1993, when Microsoft published the first digital interactive encyclopedia on a CD-ROM, called Encarta, priced at just $99. The second was in 2001, when a communitycurated, free website called Wikipedia launched. Taking the opposite approach from Kodak, Encyclopedia Brittanica looked at its industry, its company and its customers through the lens of the new technologies, made a prediction about the future and, based on that prediction, took a bold move. Having identified its core value proposition as the delivery of reliable, high-value, verifiable knowledge, Encyclopedia Brittanica replanned, restructured and rebuilt its company from the ground up to deliver that same value proposition, only in a different way. It stopped producing the only product that it had known for 244 years and began producing digital products that it sold to educational institutions.“There is a lot to learn from the Encyclopedia Brittanica case,” said D’Argenio. “The company embraced its market change, it embraced its customer change, and it rethought what it needed to do to be successful. Because it owned that disruption internally, it was never disrupted from the outside. It continues to operate today and is as profitable as it has ever been.”"

Aug 1, 2019

By R. S. Fowkes

The degree and manner of packing of bulk materials influences all phases of their loading, such as by a front end loader or a dragline, and their mechanics of flow, such as through a binhopper or an ore pass. The most important quantity in analyzing the handling of a bulk material is its shear strength which depends primarily on the same parameters as those that determine the packing state. Some of these are size, size distribution, moisture content, particle shape, particle orientation, and cohesion. The variables that affect the packing state arc vibration, pressure, intensity of deposition, velocity of deposition, and, when the material is confined, container used. The analysis of packing by a number of investigators has been done almost entirely with spherical particles. Most of these studies have dealt with monosized spheres. There is scant information on particles with angular shapes. Since most of the investigations by far have been concerned with ceramics and powder metallurgy, the particle sizes and ranges of size distribution have been small compared to those generally found in mining after fragmentation.

Jan 1, 1974

By Guangyi Sun

Wall rock classification method for coal mine support is the main factor affecting mine support. It is greatly affected by the combined effect of randomness, fuzziness and human being's incomplete knowledge. There are several coal rock classification methods. Using different rock classification methods the same engineering rock mass can be classified into different classification leading to different construction practices.

Jan 1, 2005

By Y. Zhang, M. Yekich, C. Zhou, C. Jobes, J. Galanko, D. Tuchman, J. Srednicki, J. Carr

The continuous personal dust monitor (CPDM) is an essential instrument for working in hazardous environments, is used to monitor real-time coal dust exposure, and is mandated by the Mine Safety and Health Administration (MSHA) for underground coal mines. Researchers from the National Institute for Occupational Safety and Health (NIOSH) found that it is possible for electromagnetic interference (EMI) between a CPDM and a proximity detection system (PDS) to occur. Various approaches have been taken by researchers and manufacturers to address this EMI issue. Administrative controls were recommended to keep the CPDM six inches away from the wearable PDS device. Shielding pouches were made to contain the electromagnetic (EM) emission from the CPDM. Metal shielding was added to major EM emitting components. EMI filtering with large capacitors was introduced to mitigate EMI. Most recently, a novel magnetic-field-cancellation-based approach was developed and achieved remarkable results. In this paper, we provide a comparison between these approaches. The pros and cons of each approach are presented and discussed, so that mining device manufacturers and operators can best evaluate the technology and controls that improve the health and safety of mine workers.

Feb 1, 2023