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By M. H. Rauschkolb, J. A. Cremeens

Geotechnical solutions were developed for closure of two historic, remote underground mines in the deserts of southern California. Closure criteria included access closure, minimal site impact, and optimum use of native materials. The closure designs and construction activities incorporated techniques for protecting sensitive biota, particularly bats and desert tortoise. The types of mine openings that were closed include adits, declines, shafts, daylighted stopes, and dugout dwellings. The desert locations permitted implementation of cost-effective closure techniques that relied upon the use of native materials. The strategies and techniques developed for these desert closures are adaptable to other climates.

Jan 1, 2002

By Turan Uysal, Ramazan Aydogmus, MURAT ERDEMOGLU

The paper investigates the effects of calcination for thermal activation and intensive milling for mechanical activation on aluminum recovery by acid leaching of pyrophyllite ore enriched via attrition scrubbing and froth flotation. The study compares these methods in terms of energy consumption and aluminum recovery, concluding that mechanical activation is more economical and environmentally friendly.

Nov 1, 2023

By Madan M. Singh

A new mining project can raise questions about what effect it will have on the community after it closes. Historically, little was done by communities to plan for and accommodate the changes in the economic infrastructure when a mine project is finished either after the ore runs out or if market conditions deteriorate and make it unprofitable. Projects that were underfunded were generally unable to withstand periodic market downturns. However, data in a recent study conducted by the Seidman Research Institute leads to the conclusion that, even when a mining project is terminated, there can be (and, in the specific case studied, is) a residual beneficial economic effect in the community, which lasts for a long period of time.

Jan 1, 2010

By Willard A. Murray

Investigations of underground coal gasification (UCG) have been actively pursued by the U.S. Department of Energy since the early 1970s; the Lawrence Livermore National Laboratory (LLNL) conducted its first field experiment in 1976. In conjunction with field and laboratory studies of the process of recovering energy in the form of combustible gases from the burning of coal deposits in situ, an extensive environmental program has been conducted at LLNL under the auspices of both the U.S Department of Energy and the U.S. Environmental Protection Agency. This program has focused on groundwater contamination and ground surface subsidence caused by UCG. The material presented in this paper is a summary of results from the environmental studies of UCG activities conducted by LLNL as described by Mead, et al. (1981) and supplemented by the author's experience with this program in 1980 and 1981. The following sections describe specific groundwater contamination and surf ace subsidence problems encountered during field experiments in northeastern Wyoming, and will discuss implications of preliminary findings from geohydrological investigations of a site in southwestern Washington. Finally, possible environmental control technologies that are most likely to be effective in mitigating environmental impacts are discussed.

Jan 1, 1982

By J. J. Kollé

A compressed-water hydraulic pulse generator (HPG) for nonexplosive blasting of rock and con¬crete is described Energy is stored in the HPG by compressing water to ultrahigh pressure. A large, fastopening valve discharges the com¬pressed water, resulting in a high-energy impulse. The HPG can be used for small-scale bench blasting by discharging the water through a nozzle that is closely fitted into a borehole. A bench blasting system requires an HPG, a drill and an indexing mechanism to allow insertion of the HPG nozzle into a drilled borehole. Systems with discharge energies ranging from 40 to 250 kJ have been used to excavate hard rock, including andesite, granite and quartzite. The largest system can excavate 15 t/h (16.5 stph) of massive quartzite based on a 2-min cycle time for hole drilling. Blasting with an ultrahigh-pressure hydraulic pulse generator was demonstrated as an effective means of excavating hard massive rock under the confined conditions of a tunnel opening or underground sloping panel. Hydraulic blasting provides a continuous mechanized mining capability that is well suited for deep-level mining and urban excavation sites where explosives are prohibited

Jan 1, 1997

By X. Tang, N. Ripepi

The Langmuir model has been widely used for the coal-methane sorption process through an isothermal test. However, even though the temperature-dependent Langmuir model was recognized theoretically and experimentally, the quantitative relationships between the Langmuir constants a and b and temperature have not been clarified and confirmed by laboratory test data. This paper collects 158 methane-coal sorption data under different temperatures that apply the Langmuir model to the relationships between the Langmuir constants a and b and temperature. Even though the Langmuir model cannot be used to show the physical state of methane adsorption on coal, it is widely used because of its simplicity and the reasonable explanation of its parameters a and b. The results from these published isothermal tests indicate that (1) there is no consistent relationship between Langmuir constant a and temperature, (2) the Langmuir model is a temperature-dependent model whose temperature-dependent feature is mainly shown by the relationship between the Langmuir constant b and temperature, and (3) the relationship between the Langmuir constant b and temperature can be described by both exponential and linear relationships with dried coal. This paper provides a database for the temperature-dependent Langmuir model that can be used for the reservoir simulation of coalbed methane reservoirs and for the coal seam degasification modeling of underground coal mines, considering the heating effects induced by geothermal and heat injection through factors such as hot water, hot steam and ultrasonics.

Jan 1, 2016

By Harold J. Schock

This paper describes an experimental method for the monitoring of diesel-generated exhaust gas pollutants in a dead-ended drift for the purpose of assessing the effect of control approaches. Experiments were conducted to determine the relative merits of these ventilation configurations: no auxiliary ventilation, induction ventilation at the entrance to the drift, and ventilation of the dead-ended drift with positive displacement tubing. The drift used in this experimental work was approximately 105 ft. (32.0 mf long and slightly downsloping, with an average height and width of 8 ft. (2.4 m) and 28 ft. (8.5 m1 , respectively. The data were gathered for assessing these ventilation methods and for gathering data to support a computer model of the dispersion and mixing processes. For this drift, it was found that ventilation with positive displacement tubing provided the best removal of diesel-generated pollutants. Induction ventilation appeared to be the least effective of the three methods examined. A comparison was also made between personal monitoring and area monitoring. Results of this analysis showed that in regions of high concentration gradients, it was not possible to get good agreement between point sampling and personal monitoring. In well-mixed areas, good agreement between the two methods of monitoring was obtained.

Jan 1, 1980

By Setareh Afrouz, Emily Sarver, Cigdem Keles

The resurgence of severe lung disease among US coal miners since the mid-1990s has led to efforts to better characterize and monitor respirable dust exposures, particularly focusing on mineral constituents from rock strata surrounding the coal. A rapid analysis method for silica (quartz) mass using direct-on-filter Fourier transform infrared (FTIR) spectroscopy has been developed, which can also estimate kaolinite, a primary silicate mineral in many coal mines.

Feb 24, 2022

By Richard E. Barrett

The relationship between coal characteristics and power plant performance has become a matter of increasing interest to utilities. This relationship can affect the value of coals, decisions as to coal washing, setting penalties for delivery of coal that fails to meet specifications, and justifying buying better coals (at higher costs) before public utility commissions. The study described in this paper was directed to identifying how coal characteristics impact on boilers and related coal and gas handling systems. TVA data for the period 1962-1980 was the basis for the study. Models were developed for boiler efficiency, boiler availability, and maintenance costs as a function of such coal characteristics as ash, sulfur, and moisture content and boiler age. Boiler load and maintenance efforts were considered as variables in some of the models, but were found not to be statistically significant. Although the results of this study are strictly applicable to only the TVA system, they can serve as guides or first approximations for other utilities.

Jan 1, 1983

By T. J. Lutz, D. S. Yantek, L. Yan, J. R. Srednicki, J. A. Yonkey, G. T. Homce

Federal regulations require the installation of refuge alternatives in underground coal mines. Of the inuse refuge alternatives, more than 95 percent are mobile refuge alternatives, with the remainder being built-in-place (BIP) refuge alternatives. Heat/humidity buildup has been one of the major concerns with mobile refuge alternatives. For BIP refuge alternatives, however, there is a lack of in-mine heat/humidity test data to determine the extent of heat and humidity buildup. To quantify heat/humidity buildup in BIP refuge alternatives, the U.S. National Institute for Occupational Safety and Health (NIOSH) performed a series of heat/humidity tests on a 60-person BIP refuge alternative with and without a borehole air supply. At various times during the year, tests were performed with cooled, heated or unconditioned borehole air to examine how various outdoor temperatures may affect the thermal conditions inside a BIP refuge alternative. The results show that the air supplied to a BIP refuge alternative may require heating or cooling, depending on the outside air temperatures and the temperature of the mine. For example, during tests with an external ambient temperature above 21 °C (70 °F) and a relative humidity of 90 percent, providing 13 °C (55 °F) dew point air at 775 scfm, which is slightly higher than the mandated flow rate of 12.5 scfm per person, kept the internal apparent temperature below the mandated 35 °C (95 °F). Results for each test case are presented.

Jan 1, 2018

By Arthur B. Cummins

It is appropriate to discuss diatomite at an AIME meeting in San Francisco. California has led the nation, and the world, in the production of diatomite products for more than 40 years. It appears that our State will maintain this position for a long time to come. Diatomite today ranks high in the list of California mineral commodities, with a total value since 1889 well in excess of $100 million. California's production has more than doubled since 1942. In 1959, the value of diatomite production in California is exceeded only by the following industrial mineral materials-borates, stone, sand and gravel and cement20,28. Also, not unimportant is the production of diatomite in each of our other Pacific Coast States, including Nevada. First, let us define diatomite. It is a sedimentary siliceous rock of organic origin, which consists mainly of the fossilized remains of diatoms. Diatoms are microscopic aquatic plants which have the capacity of precipitating silica bio-chemically so as to form a part of their organized structure. In the economic sense, we are not concerned with the numerous types of sedimentary materials which contain minor amounts of diatom residues, or with impure or highly indurated siliceous materials, which may have been formed from diatomite2. Diatomite (synonyms--diatomaceous earth, kieselgurO is a term generally restricted to material of such qualities as to be suitable for commercial uses. Diatomaceous silica is a designation which is best used to distinguish the basic component of diatomite, that is, the substance of the silica shell itself, and which is the major' constituent of beneficiated diatomite or processed diatomaceous products.

Jan 1, 1959

By M. Ralchenko, C. Samson, M. Svilans, C. Walsh

"Through-the-Earth (TTE) radio has been proposed as a means of emergency communications in mines. The propagation of a TTE radio signal depends chiefly on the subsurface conductivity distribution. Robust forward models of signal propagation can be computed based on a realistic conductivity estimate. These models can be used, for example, to optimize frequency, estimate signal range, identify zones of anomalously strong or weak signals, or to optimize the position of the above-ground TTE radio unit. A method was developed to determine the conductivity distribution of a mine overburden using TTE radio transmission data. At multiple locations in an underground test mine, we recorded a wideband electromagnetic signal, spanning a frequency range of approximately 500 to 8,500 Hz, transmitted from a vertical magnetic dipole at the surface. Using a finite-difference time-domain forward modeling code, a layered Earth conductivity model that accounts for topography was fitted to the observed data, which minimizes the difference between the calculated and observed attenuations for each transmitter-receiver pair, for each frequency of interest. Introduction and objectiveThrough-the-Earth (TTE) radio has been proposed for emergency underground communications. The most common type of TTE radio is based on the transmission and reception of signals by electromagnetic induction. These signals are in the extremely low to very low frequency range — in practice, between 400 and 9,000 Hz. This technology was historically developed for mine safety, although recently other applications have been suggested, such as communications in civilian infrastructure like high-rise buildings or tunnels, in the military, and even for wireless detonation and activation. In a coal mine, which is a setting of particular importance for TTE radio due to the higher risk of accidents, day-to-day communications can be done through a wired link. High-frequency line-ofsight systems, whose signals cannot penetrate rock, are also used for communications from nonfixed points. Another option is a leaky feeder system, which is a permutation of a line-ofsight system and a wired link, where a partially shielded coaxial cable allows the signal to “leak” (Delogne, 1982). In an incident such as a mine collapse or explosion, a TTE radio system can still provide a communication link, as wired systems can be severed, and line-ofsight systems cannot penetrate through collapsed portions of the mine, or to the surface (Forooshani et al., 2013; Yarkan et al., 2009)."

Jan 7, 2018

By Ray H. Hario

Background of Erie Mining Company Erie Mining Company, managed by Pickands Mather & Co., is one of the largest producers of iron ore pellets in the United States. The plant is located at Hoyt Lakes, Minnesota, sixty-five miles north of Duluth on the eastern end of the Mesabi Range. Taconite Harbor, situated on the north shore of Lake Superior, is the location of its Power Plant and shipping facilities. (Figure 1) Even though the plant commenced operation in September, 1957, its true be-ginning can be traced back to 1931 when Pickands Mather, in conjunction with Bethlehem Steel Corporation and Youngstown Sheet and Tube Company, began investi-gating the possibilities of processing low grade ores. In 1940, Erie Mining , Company was formed. During the early and middle 1940's, laboratory and pilot plant research was proven to a point where a preliminary plant was deemed feasible and built in 1948. This plant had an annual capacity of 203,200 t (200,000 long tons) per year and, until mid-1952, was the only taconite plant in existence using commercial-size equipment. During this period, ownership of Erie Mining Company was expanded to include Interlake, Inc. and The Steel Company of Canada, Limited. In 1953, authorization was obtained from the owners to build a 7.62 M t (7.5 M long tons) per year plant at a cost in excess of $300,000,000.

Jan 1, 1977

By A. Hajati

The main purpose of this study was to find the optimum values for factors affecting the Zn recovery rate using oxine or dithizone as a chelating agent collector during flotation in a Hallimond tube. Eight control factors, including four levels of pH, oxine/dithizone, corn starch, sodium thiosulfate, sodium citrate, sodium silicate, conditioning and floating durations were considered in a Taguchi experimental design technique. An L32 orthogonal array was applied to determine the signal-to-noise (S/N) ratio. Analysis of variance (ANOVA) was used to determine the optimum conditions and the most significant parameters affecting the reaction rate. Analysis of the experiments using the Taguchi approach indicated that pH had the highest contribution to the recovery rate of zinc oxide particles. The results showed that the recovery rate of zinc increased by 43.4 ± 3.0% and 24.9 ± 3.2% using oxine and dithizone, respectively, under optimum conditions with a confidence level of 90%.

Jan 1, 2010

By Kwame Awuah-Ofei, Sisi Que, Shaochun Yuan, Yumin Wang, Ziwei Ding

This research sought to facilitate improved stakeholder analysis in mining by providing further insights into the preferences of local community members using discrete choice theory. While recent research has demonstrated the usefulness of discrete choice theory in mining stakeholder analysis, no previous work has examined which discrete choice model (DCM) is most suitable. This paper provides a research note on a case study in a mining community that was performed to compare three DCMs. After a thorough examination of the benefits and deficiencies of all models, this study concludes that the conditional logit model stratified by questions is the most useful DCM for mining stakeholder analysis. The recommendation is based on the usefulness and accuracy (ability to match the survey data) of this model.

Jul 25, 2022

A computer simulation of the automatic control of continuous mining machines has been prepared, similar to previous simulations of longwall mining systems and coal thickness sensors. The simulation allows for programmed variation of the horizon detection method, the azimuthal guidance system, the type and configuration of the miner, varying hardness in the unmined face material (leading to varying error in the machine heading), and the miner's cutting cycle. It simulates control of the miner in three axes. Use of the simulator makes it possible to anticipate problems arising from the complex character of underground mining, which include unpredictable multi-pass coupling and unpredictable variation in geological conditions.

Jan 1, 1993

By John Matthews

During 1982 and 1983, it became increasingly clear that North River No. 1 Mine would have to buy a set of replacement longwall shields. Despite extensive efforts to make improvements, the shields that were in place at that time were incapable of holding the roof. North River Energy had limited experience in specifying and acquiring longwall roof supports, but a great deal of experience with our conditions and needs. We there- fore compiled a shield evaluation method that uniquely responded to our situation. The resulting system emphasized teamwork among operating, maintenance and engineering personnel. The charge from management was threefold: select shields to support maximum expected loads, optimize face operations, and pay attention to detail. Final selection was made objectively, based on all available information. We chose a 5516 KN (620 tons) support with a minimum yield load density of 760 KN/m2 (7.9 tons/ft2). This paper reviews our process of specification, design, prototype testing, and fabrication, and offers some relevant suggestions.

Jan 1, 1986

By Jun Yuan

Kaolin clays from five different commercial deposits in Georgia were studied to understand the variations of zeta potential and related fundamental properties. The results suggest that higher negative zeta potential is related to exchangeable or soluble calcium ions in the clays.

Jan 1, 1997

By R. E. J. Putman

The, principle purpose of applying control to any process is to improve -its profitability. Even when considering the impact of a plant on its surrounding ecology this is still, true, since the sanctions felt most immediately from violations of the regulations are the economic penalties or fines which result. 'Economic performance can be improved within a plant in several ways. Steps can be taken to cut the cost or quantity of resources (power, water, steam, reagents) consumed per ton of throughput. Alternatively the operation of the plant can be changed so as to increase product yield per ton of throughput. Or the cost of labor and plant overhead per ton of product can be reduced by raising the total 'throughput, assuming-that the increased amount of product can be sold for the same unit price. In designing a program to improve plant performance, all three routes should be borne in mind. To maximize the return on investment over a longer period, it is also desirable to set up a comprehensive plan of improvement, equipment being specified at each step in the implementation so as to ensure that it fits in with later requirements later implementation being either by means of modular additions or by having the necessary interfaces built into the original equipment. It is much cheaper in the long run to buy features which have been factory-installed, than to have to make provision for their later addition in the field. This paper examines some ways of improving plant performance by the application of various process control techniques using both analog and digital con¬trol equipment. A general philosophy of application is suggested and specific examples described.

Jan 1, 1972

By M. Fan

Coal has in general a wide range of density from minus 1.3 to plus 2.0 g/cm3 because of its variations in purity, rank, and porosity, etc. The coal density has great impact on froth flotation performance, but much less attention has been paid to particle density than particle size. Our previous research results demonstrated that cavitation-generated nanobubbles around 700 nm in diameter can significantly improve coal and phosphate flotation performance over a wide particle size range. In this study, the effect of nanobubble on the flotation performances of different density fractions (minus 1.3, 1.3-1.4, 1.4-1.5, 1.5-1.6, 1.6-1.8, 1.8-2.0, 2.2-2.2, and plus 2.2 g/cm3) of coal was investigated using a bank of 10-liter flotation cells, a specially designed 50-mm-inside-diameter column, and a 152-mm-inside-diameter column. It was found that nanobubble has the biggest impact on the flotation performance of 1.4-1.8 g/cm3 medium-density coal particles.

Feb 23, 2014