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By P. R. Pereira

This paper presents a comparison between the simulations of a semi-empirical model and a theoretical model for the prediction of radial stress in rock. The results of the simulations were compared to the results of a field test. The comparison of the radial stress predictions shows that in the semi-empirical model use of the plane wave approximation as the basis for the prediction of the radial stress provides a much better result than the theoretical model. The theoretical model includes the correct elastic wave geometry and theory but fails twice, firstly by considering the charge as a point (unit) energy source therefore; and secondly by using a Delta function with a very sharp rise and decay time to simulate, with no distinction between non-linear and linear zones, the attenuation of the energy per unit volume at the shock wave front as the wave moves away from the borehole. The results of the semi-empirical model were within the same order of magnitude as the results from the field test whereas only one result from the theoretical model came close to the result of the field test. However, even this closer result for the theoretical should be taken with caution as there was no measurement in the field test made at this distance from the borehole. Finally, because of its potential portability, convenience, and cost-effectiveness the theoretical model can be a most valuable tool for mining and civil construction operators in the early design of blasting rounds and of the mining operation itself.

Jan 1, 1993

By Behzad Vaziri Hassas, Firat Karakas, Mehmet Celik, Onur Guven

Since dewatering is a costly process, removal of moisture from relatively fine size lignites is an important industrial problem. As the lignite gets finer, the presence of micropores and relatively low hydrophobic nature of lignite lead to trapping of large quantities of water in the coal matrix. Lignites used in power stations need to be dried to a certain degree of humidity before it is transferred to the combustion chamber. It is generally wise to dewater coal as much as possible by physical means before it is dried. However, dewatering cost in some cases may be prohibitive. Thus, sometimes removal of even little percent moisture may be of great help in such operations. Surfactants have been used to increase the efficiency of coal dewatering. It is crucial to select appropriate type and amount of surfactants in order to get higher efficiency. Since the hydrophobic characteristic of coals increases with increasing the coal rank, dewatering of bituminous and anthracite can be accomplished using low HLB surfactants (Oily), however, these surfactants are not efficient in the case of low rank coals like lignites and brown coals. It is suggested that adsorption of low HLB surfactants on high rank coals is governed by Acid-Base interactions rather than electrostatic and van der Waals forces. Since this characteristic in lignites is not strong enough, low HLB surfactants could not be effectively adsorbed on low rank coals to make surface more hydrophobic. In this paper, a special set-up has been designed to study the effect of high HLB surfactants on dewatering of fine lignite particles. It is shown that high HLB surfactants function more efficiently on low rank coals than low HLB ones.

Jan 1, 2014

By R. Sharon

Barrick Goldstrike Mines, Inc. Betze-Post open pit operations, located in northeastern Nevada, have experienced slope instability attributed to the presence of generally weak rock mass conditions, local adverse structural geology and perched groundwater. Ground movements are monitored with acombination of optical survey, extensometers, inclinometers, and time domain reflectometry (TDR).The slope monitoring system at Goldstrike includes two robotics theodolites, which provide real-time coverage for all highwall areas. Survey instruments are housed in specially designed climate controlled shelters in locations where all slopes can be observed. A “remote” computer housed with each theodolite collects data. The “base” computer, located in the mine offices, is used to access data from the remote computers via radio modem.

Jan 1, 2000

By M. J. Ankeny

Coal-mine haulage ranks second as a cause of coal-mine fatalities, and the prevention of such accidents will materially improve progress in safety in the coal-mining industry. Beginning March 1950, Federal coal-mine inspectors were made responsible for completely investigating all fatal accidents in and around coal mines. During these 10 months, Federal coal-mine inspectors investigated 447 fatal accidents. This is a study of 121 of the fatal haulage accidents investigated, which constituted 27 percent of fatalities from all causes. Haulage employees represent only 12 to 15 percent of mine personnel, but, on the basis of accident frequency, their work is the most hazardous in coal mines. Fatal haulage accidents occurred in 53 bituminous coal-producing counties representing 14 States and Alaska. The physical conditions represent a cross section of' producing coal beds. Mining and transportation methods vary, from those of small hand-loading mines to those of modern mechanized mines.

Jan 1, 1951

The energy supply in the 21st century is still secured by coal. According to estimates of the International Energy Agency (IEA), coal will have the same importance as oil for the world-wide supply of energy until 2030. Coal is also an important element of EU policy, its future use is closely linked to effectively addressing the environmental challenges it poses. Hard and brown coal represent approximately 80 per cent of European Union (EU) reserves of fossil fuels and coal utilisation can co-exist with the development of power generation based on renewables. Europe is the world's third largest consumer of coal behind China and the United States.The Czech Republic is poor in energy resources except for coal. Brown coal is relatively abundant (mineable reserves estimated at 1800 Mt, output 48 Mt/a) and significant quantities of hard coal (mineable reserves 900 Mt, 13 Mt/a), much of it suitable for coke production, are also present.Severoceske Doly (SD Company), the biggest Czech coal mining company (22 Mt/a, 48.6 per cent Czech market share) and one of the biggest in Europe, reinforces despite the last deep crisis in the Czech and European economies its long-standing stable and strong market and financial position. From 2009, the SD Company co-owns, with partners, a brown-coal mining company MIBRAG (21 Mt/a). SD Company invests in large mining equipment (eg new giant spreaders and bucket-wheel excavators, extension of overland belt conveyors), rebuilds and upgrades mining and processing installations, auxiliary and other machinery. We should see the investment we make today in tomorrow's mining and reclamation as an opportunity and not as a burden. They enable to make our position more resistant in the longer term. Projects focused on the environment and operational safety went hand in hand with these efforts.R&D activities relate to technical innovations, improvements of mining equipment, research and evaluation of conditions for extracting coal seam and/or overburden and mitigation of environmental impacts, utilisation of coal in new products. The company spends considerable amounts on reclaiming affected land and creating a new post-mining landscape.Our dialogue with influential stakeholders in the region where we operate contributes to the long-term improvement in the quality of life of local residents. Such dialogue with communities in the last ten years has been instrumental for confidence building. SD Company helps to develop many projects of towns and villages in its vicinity. The stable and transparent relations with our neighbours are in accordance with our basic principles of corporate social responsibility.

Dec 6, 2010

By J. R. Thoenen

This paper outlines briefly results of seismic measurements recorded in the vicinity of quarry blasting under practical operating conditions. The data cover field work done from January to the middle of August 1930, during which time records were made of 61 blasts in 19 quarries. Of the tests made, one was in biotite-gneiss, two in dolomite, two in a flintlike volcanic complex, three in gabbrodiorite, five in trap rock, and six in limestone. One quarry was in Alabama, two were in South Carolina, two in New York, four in Kentucky, five in Connecticut, and five in Massachusetts. Explosive charges ranged from 0.30 pound to 41,900 pounds, and the method of shooting varied from mud caps through hammer and wagon drill holes to churn drill holes and coyote tunnel shots.

Jan 1, 1937

By Frank Parrish

THIS REPORT by the Federal Bureau of Mines presents data on water-supply wells used by waterflood operators in North Texas and shows the distribution of permeable source sediments. Averages of well characteristics, including static fluid levels, working fluid levels, net thicknesses, producing rates, and depths, are presented and discussed. Essentially all water used in waterflooding is mineralized water from consolidated sediments. This study is concerned with the geology and distribution of these mineralized source sediments, whereas previous work in this area was predominantly a study of shallow sources of potable water. Tables, isopachous maps, and electric-log cross sections are included to describe the several source aquifers. In general, water-producing capacity increases with depth of the sediments. Wells completed in Cretaceous sediments 82 to 600 feet deep yield 50 to 600 barrels of water daily, whereas those completed in Pennsylvanian sediments 360 to 4,110 feet deep yield 100 to 7,000 barrels daily. Although deeper formations are used where oil and water are produced conjunctively and where large withdrawal rates are required, insufficient well data prevented mapping of deeper formations.

Jan 1, 1961

By N. Arbiter

If two fluid phases are brought into contact with a solid, one fluid may completely wet the surface to the exclusion of the other, or both may wet it, forming a three-phase line of contact. These relative wetting tendencies are quantified by the contact angle 0 which is related by Young's equation (1,2) [12 cos? = 13 ? 23] [to the three interfacial tensions (3). No contact angle for the first fluid, indicating that it does not wet the solid in the presence of the second, means that the difference between the two solid-fluid fluid surface tensions, - 8 is greater than (or just 13 -23 equal to) the fluid-fluid tension 12; a finite angle indicates that the difference is less.*]

Jan 1, 1964

By R Shelton

The Big Wainihinihi River and tunnel are located on the western side of the Southern Alps of New Zealand within the active Alpine Fault zone, which marks the boundary between the Pacific and Australian Tectonic Plates. The tunnel was built over 100 years ago to supply water for gold mining, but it now conveys water from a high-energy intake to a canal that supplies three of TrustPower’s hydro-electric power stations with a combined installed generating capacity of 10 MW. Part of the tunnel passes through an unstable 50° schist slope, which fi rst suffered a wedge failure in the 1929 Arthur’s Pass Earthquake and was reinstated in the mid-1970s for hydro generation. In 2008, TrustPower’s monitoring system showed that the wedge failure had remobilised and that urgent remediation was required.Harker Underground Construction (Harker) was awarded a design-build contract to restore the tunnel to service by tunnelling a new central section. Their geotechnical engineers, Peters and Cheung, reviewed the tunnel’s stability and proposed a new, safer tunnel alignment, deep behind the failure wedges. This work was based on their failure model, cost-benefit studies, and engineering geology completion mapping at the time of re-opening.Construction innovation was an important factor in ensuring the project’s success, as were detailed geological and geotechnical information, a robust methodology, strong client relationship and planning. To suit the varying rock conditions and restricted space, Harker combined a traditional drill-and-blast method with light-weight modular steel sets and timber supports to reduce construction costs and mitigate support risk. To make material handing easier in the tight conditions, a special electric locomotive was designed and built and blasting confi gurations were adapted to suit varying rock conditions in the highly fractured schist.The isolated site meant interesting and unexpected challenges, particularly communications and resources (both human and material). Despite that, the project was completed within budget, on schedule, and with no lost-time injuries.

Mar 8, 2011

By Lawrence L. Davis

This paper describes current research by the Bureau of Mines to develop technology for improving efficiency and productivity in metal/ nonmetal mines. The research program addresses a wide variety of problems associated with each of the major categories of mining: underground mining, surface mining, in situ mining, and premining investigations. An overview of the Bureau's research activities is given with emphasis on underground mining. In particular, two innovative and promising concepts currently under development are described: a unique shaft sinking system that uses an impact hammer for rock fragmentation, and a low-profile, portable crusher for underground hard-rock applications.

Jan 1, 1979

By H. W. Smith, C. L. Lewis

"A process control computer has been installed in the Lake Dufault concentrator to: (a) control the on-stream X-ray analyzer and convert chart readings to elemental percentages, (b) calculate the flow rates required for the most important flotation reagents, using the amount of material entering the process, the analyses and the slurry pH, and (c) set the reagent feeder to these flow rates automatically. Although this project was largely experimental, to gain knowledge and experience in flotation process control, the objectives have been met and fully automatic computer control is now the normal mode of mill operation.This paper describes project planning and defines the system with respect to both control design and functional design. System operation -as seen by the mill operator -is detailed. Implementation of the system is described and the system is discussed in terms of its success, economic justification and future plans."

Jan 1, 1969

By Thomas M. Barczak, Joe Bower, Jinsheng Chen

Pumpable roof supports provide an alternative longwall tailgate roof support and have grown in usage during the past few years. Heintzmann Corporation has been installing pumpable roof supports at the RAG Resources Emerald Mine in western PA since 1998, where they have provided effective roof control in their longwall tailgates. Despite the success of these supports in this application, questions remain regarding critical design issues for optimizing the use of this support technology. The support loading profile is characterized by a high initial stiffness with peak loading occurring at less than one inch of convergence, followed by significant load shedding with a post failure capacity comparable to that of wood cribbing. Therefore, the key to optimizing the support utilization is to provide sufficient load density to prevent convergence from occurring beyond the peak loading capacity. This requires an understanding of how the supports interact with the ground conditions, hence measurement of the ground reaction curve. In order to obtain this information, pumpable roof supports were instrumented to measure support loading. Roof deformation and roof-to-floor convergence measurements in the vicinity of the instrumented supports were also made. The experimental parameters for the installation were the support spacing and water-to-solids ratio of the grout, which controls the grout strength and ultimately the maximum capacity of the support. The study clearly shows that at this mine a 24-inch diameter support is fully capable of providing adequate ground control under depths of cover of 750 ft as only 50 pct of the available support capacity was utilized outby the longwall face. It was also shown that the 2.00 to 1 water-solids ratio, despite providing a slightly softer support response, is sufficient for maintaining the same degree of roof control provided by the traditional 1.75 to 1 grout mix. The 10-ft spacing of the supports did not cause any ground control problems outby the face. However, inby the face the performance of the support is degraded once the peak capacity of the supports is exceeded. It appears that the large load shedding behavior, which is characteristic of this support following peak loading, allows the immediate roof to separate. When this happens, the support is unable to regain control of the roof in time to prevent failure of the immediate roof beam.

By Yi Luo, Jian Yang

Subsurface strata movements and deformations associated with longwall mining operations in underground coal mines could cause various disturbances to subsurface mine structures, ground water bodies, and coalbed methane reservoirs. In order to assess those disturbances correctly and to design effective and efficient mitigation measures, it is necessary to develop an accurate prediction model for subsurface strata movements and deformations. Decades of research have demonstrated that variations of stratification and lithology in the overburden have significant influence on the subsurface strata movements and deformations during ground subsidence process. The key strata theory states that the thick and hard key strata serve as the backbone of the overburden and control the movements of the thin and soft weak strata located above them. From an engineering standpoint, the overburden strata are subdivided into several individual groups by the key strata with each group consisting of a key layer at the bottom and weak layers overlying it. A new subsurface subsidence prediction model considering the key strata effects on subsurface strata movements and deformations has been proposed. In this method, elastic modulus, specific weight, tensile strength, and uniaxial compressive strength (UCS) of each layer are used to identify the key layers and to determine the needed subsurface subsidence parameters. The influence function method, proven to be accurate and versatile for surface subsidence prediction, was employed to predict the subsidence on each of the overburden layers from mining horizon progressively upward to ground surface with the assumption that the predicted subsidence on a given layer serves as the subsidence source for the layer immediately above. The enhanced subsurface subsidence prediction model has been demonstrated with an actual case to show its applicability and improvement.

Jan 25, 2021

By Henry P. Cole

A series of studies are described that identify critical health and safety skills needed by underground coal miners for coping with mine emergencies. First aid and self-rescue and escape were selected as two broad performance domains that include many subordinate skills needed for preventing, recognizing, and coping with mine emergencies. The performance domains and their objectives were used to direct the development of simulation exercises that permit miners to experience mine emergencies in the safety of a training room. The exercises are based upon research with similar simulations for the training of flight crews and medical personnel in information gathering, judgment, and decision making skills. Exercise content is drawn from actual mine accident and disaster case studies. The exercises incorporate recent principles of cognitive psychology and instructional design. Initial studies in annual refresher training classes suggest the exercises are stimulating for miners and their instructors, easy to use and read, sufficiently complex and authentic to challenge experienced miners, and useful devices for both teaching and testing critical problem solving skills required for preventing and minimizing emergencies.

Jan 1, 1988

By H. C. Fowler

The social economy, or public interest, and national defense require wise development and efficient use of the oil and gas resources of the United States. In this development and use, and in the prevention of economic and physical waste of oil and gas, the objectives of the petroleum and natural-gas industries, the Government (Federal, State, and local), and the public are the same. Differences of viewpoint generally have originated in the failure of one of the triad to have a clear or complete understanding of the motives behind the activities of the other component groups or full knowledge of what each is trying to accomplish. The Unites States Bureau of Mines through its petroleum and natural-gas division makes technologic and scientific investigations pertaining to recovery,3 preparation, refining, and use of oil and natural gas with the view of reducing waste, increasing safety and efficiency and aiding economic development.

Jan 1, 1933

By Niels Verbaan, Ernesto Bourricaudy, Ronald Molnar, James Brown, Sunil Jayasekera

"SGS Minerals commissioned an internal R&D program to develop in-house expertise to design, set up and operate REE separation pilot campaigns at its Lakefield, Canada site. A team approach was used that included expert consultants in the field of REE separation as well as in-house expertise supported by the on-site Analytical Laboratories.A mini pilot scale SX circuit was designed and constructed consisting of several modular banks of 30 stages each. About 80 stages of mixer-settlers were used to separate Pr and Nd from La and Ce contained in a synthetic REE chloride stream simulating the raffinate from an initial La-Nd|Sm-Lu+Y separation.Two pilot campaigns were operated totalling 25 days of 24/7 operation with 99.4% plant availability in the final 20 day campaign. Purities of > 99.9% in the Pr-Nd strip liquor and > 99% in the La- Ce raffinate were achieved and simultaneously sustained in the second campaign for prolonged operating periods. Key to controlling and adjusting the circuit was the rapid assay turnaround (as low as 2 hours) provided by the on-site SGS analytical lab. This permitted the operating team to modify conditions and observe the effect of changes relatively quickly considering the large number of stages. A portable XRF analyser was also used to track evolving assay trends in the circuit. The small physical size of the circuit enabled longer operation with a limited amount of sample.This paper discusses the design of the circuit, operating conditions, some of the key operating factors and controls and results obtained.INTRODUCTIONSGS Minerals commissioned the design of and built a solvent extraction (SX) pilot plant for the separation of rare earth elements (REE). The plant consists of a battery of 120 mixer-settlers set up in a dedicated piloting facility.The purpose of the programme was to develop capabilities and in-house expertise in REE SX separation technology. The program aimed to establish operating procedures, sampling regimes, and analytical methodologies and protocols for this type of process/plant. A team comprised of SGS personnel and several external consultants with prior industrial and REE separation piloting experience was assembled to achieve these objectives."

Jan 1, 2016

By J. A. Harle

Introduction When considering power in Alberta, there automatically come to mind ideas of either hydro or thermal generation, leaving in one's thought an uncertainty as to which one would propose. There is frequently an obvious source of power in some locations on our fastflowing rivers, the major possibilities being described in the report on Surface Water Supply and Water Power of Alberta issued by the Alberta Government in 1948, but it must be realised when reading that report that the sites so described will require extensive geological and other surveys before they can be exploited, and account must be taken also of the transmission distances involved in each instance. From a conservation point of view, where water power can be economically developed and power transmitted to the load centres, this should be done, and our thermal resources should be husbanded for our coming generations, especially if our water resources are falling owing to glacial shrinkage.

Jan 1, 1951

By H. J. Ramey, I. S. Bousaid

Experimental results on the oxidation reaction kinetics in the forward combustion oil recovery process are presented. A total of 48 runs were made wherein a stationary thin layer of coked, unconsoli-dated sand was burned isothermally in a combustion cell. Individual runs were made at various temperature levels to permit determination of the effect of temperature upon the reaction. An expression was obtained for the burning rate of carbon as a function of carbon concentration, combustion temperature and oxygen partial pressure. The carbon burning rate for two types of crude oil indicated a first order reaction with respect to both carbon concentration and oxygen partial pressure. The effect of combustion temperature on the reaction rate constant matched the Arrhenius equation. The activation energy was similar for the two crude oils examined. The activation energy decreased for a porous media containing clay. The rate of oxidation of crude oil at reservoir temperature was found to be significant. Other significant findings included information on hydrogen-carbon content of fuel residues, fuel reactivity and the products of combustion. INTRODUCTION The production of crude oil by underground combustion has been studied in the laboratory by many investigators.1-5 Results of laboratory and field experiments have been reported in the literature describing the forward combustion process. But as yet, no qualitative or quantitative study of the kinetics of fuel combustion involved in this process has been reported. The fuel concentration and the rate at which fuel is burned at the front are important factors governing the air requirement in a forward combustion operation. Although the fuel is essentially unrecoverable crude, the air required to burn the fuel is an important economic factor in this process. Because fuel is burned, the heat transport associated with forward combustion is a key and unique feature of this new oil recovery method. Many investiga-tors5-9 have presented information on the heat transmission and fluid mechanics involved in forward combustion. Berry and Parrish10 demonstrated the utility of considering reaction kinetics in reverse burning. From differential thermal analysis, Tadema11 presented a qualitative discussion of the nature of reactions between oil and oxygen in combustion oil recovery. Although little quantitative work has been done on the reaction kinetics involved in forward combustion oil recovery, an extensive literature does exist on combustion of carbons and oils, and carbonaceous residues from cracking catalyst pellets. Dart, et al., 12 studied the combustion rate for oxidation of carbonaceous residues on clay catalyst pellets, and found the reaction to be second-order with respect to carbon concentration, and first-order with respect to oxygen partial pressure for carbon concentrations less than 2 weight percent of the catalyst weight. The reaction appeared to be first-order with respect to carbon concentration for concentrations greater than 2 percent. Metcalfe13 noted that other workers had found that aging of the fuel during the combustion process was responsible for changing coke properties, and it accounted for the apparent second-order carbon concentration effect found by Dart, et al. It appears that burning of residues from cracking pellets is first-order with respect to both carbon concentration and oxygen partial pressure. Dart, et al., also observed that hydrogen in the hydrocarbon residue appeared to react faster than the carbon. Lewis, et al.,14 studied oxidation of charcoal, coke and graphite in a fluidized bed. Gas velocities were high enough to partially lift and circulate the carbon particles. Their results indicated first-order reaction dependency with respect to both carbon concentration and oxygen partial pressure. One

Jan 1, 1969

"1.0 INTRODUCTIONThese Guidelines reflect the state-of-the-practice of the Deep Mixing Method (DMM) in North America. DMM is an in situ mixing process that breaks down the soil structure; injects binders, fillers and reagents into the soil; and blends them with the soil. DMM is also commonly referred to as Soil Mixing. The final properties of the treated soil in situ are a function of the composition of the native soils and groundwater, the binders introduced, the mixing methods and energy, and the conditions and time of curing. Treated soils generally have increased strength and stiffness and/or reduced permeability relative to the native soils.This document addresses DMM performed by rotating single and multiple axis mixing tools, rotating cutter wheels at the end of a rigid kelly bar, or trench mixing using a rotating cutting/mixing chain around the perimeter of a rigid bar. Binder may be injected through low or high energy (velocity) jets.The treated soils created through wet DMM are heterogeneous mixtures of binder, water, soil, and groundwater. Treated soils produced by dry DMM techniques are a mixture of binder, soil, and the water already present in the native soil.DMM applications described in this document include•,Earth retention•,Liquefaction mitigation•,Groundwater seepage control and containment isolation•,Bearing capacity improvement•,Deep foundations•,Mass stabilization and contamination containment•,Embankment, levee and dam strengthening, and stabilization•,Casing replacementThis document was developed to address deep foundations applications. Use of deep mixing for seepage control is not specifically addressed. The reader is referred to documents prepared by the U.S. Army Corps of Engineers for additional information. Shallow soil mixing and the use of DMM for stabilization/solidification of contaminated soils performed at depths less than 10 feet (3 m) are mentioned briefly. Jet grouting is not covered by these guidelines."

Jan 1, 2016

By H. C. Young

This paper deals with roof bolting in Alabama coal mines and iron-ore mines from the time it was introduced in early May 1948 to May 1, 1953, a 5-year period. The Tennessee Coal & Iron Division of the United States Steel Corp. began systematic roof bolting in early May 1948 in a coal mine and in an iron-ore mine, which had some of the poorest roof conditions in the Alabama mines. After the efficiency of roof bolting had been proved by the Tennessee Co. it was gradually adopted by other companies throughout the State, until in May 1953 approximately 53 percent of Alabama's total coal production and 100 percent of Alabama's total iron-ore production, mined underground, was being produced from roof-bolted areas. Statistics in this report will show the advancement made in roof bolting in the 5 years and also the amount of roof bolting that was being done as of May 1, 1953. Significant progress has been made in the coal and iron-ore mines of Alabama in reducing the roof-fall fatality rates during the past several years by adopting systematic roof bolting. The groundwork was laid through successful experiments early in 1948 by the Tennessee Coal & Iron Division of the United States Steel Corp. in cooperation with the Federal Bureau of Mines. This experimental work was based upon the previous experience of the St. Joseph Lead Co.2/ in its Southeastern Missouri mines.

Jan 1, 1954