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By M. Kawahata

Methane sensors using principle of catalytic oxidation of methane are employed for determination of methane content in ambient air of coal mines. Certain foreign gases or vapors in the air poison the catalyst of the sensor effecting the sensor's response. After literature search of poison compounds of Pt and Pd oxidation catalyst, experimental studies of catalyst poison kinetics were made for three siloxane compounds, tributyl-phosphate, monobromotrifluoromethane, and hydrogen sulfide, selected as poison vapors. Concentration range of the poison vapors was varied in a range from 3000 to 0.1 ppb (v/v). Three siloxane vapors produced strong catalyst poison effect, followed by tributylphosphate, hydrogen sulfide and monobromotrifluoromethane for the high concentration level of the poison vapors. The poison effects are influenced significantly by concentration of the vapors. Threshold poison vapor concentrations where effect of the poison vapors on the sensor is minimal were determined experimentally. Experimental studies were made further for prevention method of catalyst poison by adsorption techniques. Use of activated carbon cloth inserted on the sensor's head prevented catalyst poisoning efficiently.

Jan 1, 1981

By Jerry Ran

Stope back caving in a mine using open stope mining interrupts the planned mining sequence and causes oversize muck and dilution with adverse economic implications. As many underground mines are mining or have plans to mine at depth, stope back caving could have significant impact on the mine sustainability. Therefore understanding the caving mechanism is important in preventing future occurrence and improving the mine economic performance. Falconbridge Ltd Kidd Mine is an underground mine using open stope method producing more than 2 million tonnes per year. Its current lowest mining level is approximately 2070m below surface and the lower portion of the orebody is being developed. In years of 2002 and 2003 the back of three stopes of approximately 1900m and 2040m below surface caved and caused substantial mining difficulties at the mine. As these caved stopes are subject to stress concentration, seismic activities and near major geological structures, the caving mechanism is much more complex than that of stopes near surface. In addition to the recorded caving history by site observations, the mine carried out cavity surveys and test drilling to define the caved profiles. The mine seismic monitoring database provided information at these stopes. Stress modeling work conducted by an external consultant provided the stress patterns at the caved stopes. Based on the field collected data and stress and seismic information, this paper presents details of the stope caving process and cavity surveyed profiles, reviews the predictability of the stability graph approach for these cases, discusses the caving mechanism and proposes preventive measures to stabilize the stope back.

May 1, 2004

By H. Reginald Hardy

This report describes the results of a research project carried out to investigate the feasibility of using transducer arrays, located on surface or in shallow boreholes, above an active coal mine to detect and locate the source of underground microseismic activity which normally occurs during mining. The initial stage of the project involves the design and development of a self-contained mobile microseismic monitoring facility capable of use in remote field locations. Following this a variety of transducers, and transducer field installation techniques were investigated to obtain optimum sensitivity and high signal-to-noise characteristics. Preliminary efforts were also undertaken to develop semi-automated techniques for analysis of microseismic field data. Using the facilities and techniques developed field studies were carried out at a number of surface locations over a central Pennsylvania coal mine operating at depths of the order of 500 feet. In particular studies were con-ducted over a previously mined development area, troubled by extensive problems of roof instability, and over two longwall panels during mining. Although many of the field studies were carried out during the development stage of the project, results in general have been most encouraging. Limited results were obtained over the development area, however excellent microseismic signals, correlating with underground strata instability, were detected over both long-wall areas, proving the general feasibility of surface monitoring techniques. More recent studies, carried out as part of a subsequent project, and utilizing modified geophone installation techniques at a third longwall site, have verified explicitly the feasibility of measuring underground microseismic activity from surface locations. Sections of typical field data are included in this report along with a brief review of the studies carried out at each of the field sites. Detailed analysis of data obtained at the second and third longwall test sites will be presented in a later report.

Jan 1, 1974

By A. J. Fejes

The purpose of this Bureau of Mines report is to provide mining industry personnel and regulatory authorities with a subsidence-reference list and annotated bibliography that will aid them in locating subsidence information and in developing their own subsidence information sources. Over 700 references are listed in the Bureau's subsidence information center bibliography; approximately 600 of these references were obtained for assessment. Of these 600 references, 167 were selected to be rated, categorized, and annotated. All literature referenced in this report was published prior to 1984. Table 1 is a cross - referenced index that classifies and rates selected references with respect to specific keywords. References are rated not on quality of content but rather on applicability to given subject areas. Appendix A is an annotated bibliography of the references listed in table 1 and provides further information of each article to aid the user in selecting articles for specific areas of subsidence technology. Appendix B is a copy of the subsidence information center bibliography.

Jan 1, 1985

Jan 1, 1987

By Robert A. Siokler

Approximately 75 percentage of the earth's land surface is comprised of shale or shale-like materials. Shale itself is composed of the residue from an almost infinite variety of weathered parent materials which have undergone deformations ranging from intense to negligible. Under standard test procedures, shales exhibit a very wide range of physical properties particularly if the test specimen is subjected to a change in moisture content, when the original test values may vary from 0 to 100 percentage. It is this wide variation in physical property values compounded by its ubiquitous presence that makes shale such a problem material to engineers. In reviewing the literature relating to shale, it is evident that the "problem" has been approached from many directions. In order to understand why shales behave as they do, investigators have sought mineralogical, geological, chemical, electrical, and physical answers. Each study yields valuable academic information, but few contribute much of value to the engineer in the field. Many valid relationships between shale strength or competency and clay type, clay content, organic content, water content, grain size, cementation, density, porosity, etc, have been established. Yet it is very difficult to extend these understandings to the in situ condition with results that can be used by the field engineer. One major reason earlier work has not produced better information lies in the ambiguity of the definition of shale. It is apparent that no one laboratory parameter can be successfully used to provide sufficient engineering information to properly describe in situ conditions. For example; shale with swelling clays will produce low strength values provided: the swelling clay is in sufficient quantity, the clay is dispersed throughout the medium involved, and there is a low value of cementation. Shales with high unconfined compressive strengths have been found with very low shear strengths. Sandy shales often provide as many ground control problems as clay shales. Shales of similar nature may provide good roof conditions in one part of a mine yet in another part of the same mine the apparently identical shale may cause substantial problems. A clear need exists to classify shale in a manner which will enable the engineer to better predict the strength and durability of shale-like materials. Studies at the University of Missouri-Rolla (UMR) have focused on finding parameters which influence durability and competency, while being discretely discernible through uncomplicated testing. Initial research concentrated on distinguishing shale8 on the basis of standard physical tests such as: unconfirmed compression, triaxial shear, and slake durability. As results accumulated, however, it became evident that moisture content played a much greater role in determining competency than had been recognized previously. As a result the focus of the research turned to developing tests which would evaluate the influence of moisture on shale behavior. The above work then became a foundation for a second phase of investigation in which a suite of standardized tests were developed to provide a classification procedure. From this study five tests were identified as being critical: Moisture Activity, Atterberg Limits, Submersion, Unconfined Compression, and Shore Hardness.

Jan 1, 1986

By Eduardo Rocha Costa

Barras trefiladas podem não apresentar o perfil desejado pelos seus fabricantes após o processo de produção, por isso, este trabalho tem por objetivo avaliar diferentes geometrias de ferramentas, mais precisamente, o ângulo de entrada e região de calibração (Hc) da mesma. Para modelamento numérico do processo, foi utilizado o software DeformTM, que possibilitou este estudo, com simulações da influência da ferramenta no perfil de tensões residuais dos produtos (barras de aço AISI1045). Foram analisados os diferentes comportamentos do material para processos com fieiras de ângulos de 15° e 20°, com foco nas variações de tensões residuais visando investigar o produto final da trefilação. Em uma das principais comparações entre as fieiras anteriormente mencionadas, observou-se uma diferença de tensões residuais de aproximadamente 206MPa no centro das barras trefiladas, resultado que somado a distribuições assimétricas de tensões em relação ao ponto central de determinado corte da barra, podem ocasionar o seu empenamento.

Aug 8, 2018

By A T. Spathis, M G. Wheatly

Some preliminary dynamic pressure data were obtained from several charges detonated in a tunnel situated in massive granite rock. The context of the work is the potential for desensitisation of explosives, failure of detonators, and sympathetic detonation due to the close proximity of inter-hole and inter-deck explosive charges to each other. Dynamic pressures were measured using piezoelectric gauges in water-filled 45 mm diameter holes adjacent to the charges. Some of the first arrival peak pressures were noisy, and although not fully resolved, may be due to reflections and the physical arrangement of the transducers and their size with respect to the monitoring holes. The estimated peak pressures were between 0.1 to 8.7 MPa at approximate distances of 2.8 to 0.8 m, respectively. Further work is planned with gauges that are disposable, have a higher pressure range, and can be used within a few borehole diameters rather than the piezoelectric gauges used in the present work.

Jan 1, 2016

By Cristiane Sales Gonçalves

O processo de injeção sob pressão de ligas de alumínio é empregado para a produção de peças diversas, destinadas principalmente à indústria automobilística, com a possibilidade de produzir peças complexas, contendo seções delgadas, e a alta velocidade de produção. O reduzido tempo de ciclo e as elevadas temperaturas envolvidas promovem danos por fadiga térmica na superfície de trabalho das matrizes, que crescem com o aumento da produção até atingirem condições que inviabilizam o uso da matriz. O presente trabalho visou estudar o efeito da nitretação na superfície do material, relacionando-o aos aspectos microestruturais e tensões residuais inseridas durante nitretação. O aço AISI H13, foi tratado para dureza de 45 HRC e posteriormente nitretado sob plasma em diversas condições de temperatura, tempo e composição da atmosfera gasosa. Os resultados obtidos mostraram que as variações dos parâmetros de nitretação afetam os perfis de dureza e de tensões residuais presentes nas camadas nitretadas, bem como os microconstituintes das mesmas. O material nitretado, após ser submetido a temperaturas da ordem de 600°C, apresentou redução no nível de tensões residuais de compressão, ocorrendo processo de alívio de tensões. O mesmo efeito não foi tão fortemente verificado no perfil de dureza do material.

Aug 8, 2018

By R. Armstrong

The stability of rock slopes is significantly influenced by their curvature in plan view. The importance of this in open pit mining is indicated by the fact that, in a deep pit, steepening of the slopes by 1° may save as much as $100 million. It is considered that there are two significant factors that play a part in the influence of plan curvature. These two factors are the effect of stress, and the effect of geological structure. The scant literature that pertains to this aspect of rock slope design was reviewed. The geometrical influence of the plan curvature was then investigated. It was seen that it has a parabolic effect on the maximum possible wedge that can fail into a circular pit, where the tighter the concave curvature the smaller the wedge. The plan curvature also affects the volume of a particular wedge, where concave slopes result in an exponential decrease in the volumes and convex slopes have exponentially increased wedge volumes. A change in the strike of the wedge did not affect the curvature’s influence on the volume, but the volumes of shallower dipping wedges were affected more by the influence of the plan curvature. La stabilité des talus des roches est très influence par la courbure de celles ci dans la vue en plan.Son importance de l peut arriver à sauver même $100 millions. Il est considère qu il y a deux facteurs importants qui jouent une influence sur cette courbure. Il s’agit de l’effet des contraintes et l’effet de la structure géologique. La brève littérature qui se réfère à cet aspect du conception sur le talus des roches a été revue. L’influence géométrique de la courbure des plans a été investiguée. Il a été vu que cela un effet parabolique sur la bosse ou le su relèvement maximum possible qui peut faillir dans un puits circulaire, ou le plus resserre est la courbure concave, le plus petit est su relèvement (bosse). La courbure plane aussi affecte le volume d’un particulier su relèvement ou les talus concaves résultent dans une décroissance exponentielle en volume alors que les talus convexes accroissent la volume de ces su relèvements (bosse). Le changement de l’orientation de la bosse (su relèvement) perpendiculairement ou obliquement n’ a par affecte l’influence de al courbure sur le volume mais les volumes des bosse (su relèvement) peu profonds étaient affectes par la courbure des plans. Die Stabilität der Felsensteigungen wird erheblich durch ihre Biegung im Plan beeinflußt. Der Wert von diesem in der Tagebaugrube wird durch die diese Tatsache, in einer tiefen Grube, steepening der Steigungen durch 1° angezeigt; kann soviel wie $100 Million speichern. Es wird betrachtet, daß es zwei bedeutende Faktoren gibt, die eine Rolle im Einfluß der Planbiegung spielen. Diese zwei Faktoren sind der Effekt des Druckes und der Effekt der geologischen Struktur. Die dürftige Literatur, die diesen Aspekt des Felsensteigungdesigns betrifft, wurde wiederholt. Der geometrische Einfluß der Planbiegung wurde dann nachgeforscht. Es wurde gesehen, daß es einen Parabolischen Effekt auf dem maximalen möglichen Keil hat, der in eine kreisförmige Grube ausfallen kann, wo, das fester die konkave Biegung, das kleiner der Keil. Die Planbiegung beeinflußt auch das Volumen eines bestimmten Keils, in dem konkave Steigungen eine exponentiale Abnahme an den Volumen ergeben und konvexe Steigungen exponential Keilvolumen erhöht haben. Eine Änderung im Schlag des Keils beeinflußte nicht den Einfluß der Biegung auf das Volumen, aber den Volu

Jan 1, 2003

By D G. Boxall

As an alternative to heavy water cooling, reactors cooled by organic liquids are being actively developed in Canada under the sponsorship of Atomic Energy of Canada Limited. One of the areas in which development has been required is that of core materials. The factors affecting the selection of fuel canning and coolant tube materials are discussed. It is shown that S.A.P. is a potentially attractive material for these applications. The fabrication of fuel sheathing is discussed. Difficulties met due to large inclusions and blistering due to high hydrogen contents have been overcome by magnetic separation and vacuum sintering of the powders. High-quality tubes can now be produced by extrusion to finished size. A study has been made of the mechanical properties of fuel-sheathing tubes and bar stock. The stress rupture properties of the tubes subjected to uniaxial and biaxial stress have been determined. The biaxial stress tests were performed by internal pressurization. For times in excess of about 200 hours, the curve of stress against time to rupture is extremely flat. The secondary creep rates of

Jan 1, 1965

By Albert J. Rambosek

The results obtained in a study of the stress conditions existing in a drill bit-point area and in the underlying rock, when the bit was in full but nonpenetrative contact with the rock, are presented. This investigation by the Bureau of Mines was the preliminary exploratory phase of a long-range program of research on rock drilling to establish criteria for the maximum economically feasible rate of rock penetration. The photoelastic technique of experimental stress analysis was the principal method used to obtain the data. Transparent models and transmitted light were employed to investigate patterns in drill-bit models and isotropic materials under the bit when subjected to a concentrated static load. Comparative stress data for anisotropic rock were obtained by the reflective photoelastic technique. Brittle lacquer and an extensometer were used obtain supplementary information wherever substantiating data were desired to check photoelastic results. The zone of maximum shear occurs along an arc near the contact face of the bit. The stress distribution pattern in an isotropic model rock near the area contacted by the bit was nearly a mirror image of that exhibited within a similar areal zone of the bit. The stress pattern in granodiorite specimens was similar, though not symmetric, to the pattern in the isotropic model rock. The asymmetry of the stress pattern in the granodiorite was attributed to the anisotropic characteristics of the constituent minerals of various sizes.

Jan 1, 1963

By B. R. MacKay

Introduction During the past six seasons the writer has been engaged in semi-detailed investigations on the coal areas lying along the front of the Rocky mountains between the Brazeau river and the Smoky River Coal Reserve (see Map, Figure 1). The purpose of this paper is to present some observations pertaining to the stratigraphy and structure of the district, touching especially upon the lithological units into which the Lower Cretaceous sediments have been divided, the thicknesses of the formations at different localities, the number, thicknesses and horizons of the principal coal seams, and the structural conditions which exist in the various fields.

Jan 1, 1930

By Tim Chapman

This general report considers what promoters of deep basement projects want from their teams and whether they get it often enough. Most large projects are based on complex financial models where the funding is related to a future income stream. Project delays and cost over-runs can critically affect the financial model. Too often, delays and cost over-runs originate in the substructure and foundations. We must take positive steps to improve our industry's reputation for reliability.

Jan 1, 2006

By W. J. Kroll

Despite the fact that barium minerals are plentiful and widely distributed in nature, this element is one that we do not yet know how to prepare cheaply in metallic form. This is due to its chemical activity, as evidenced by its great affinity for fluorine, chlorine, oxygen, nitrogen, hydrogen, and sulfur. Furthermore, it forms a very stable subchloride and subfluoride, which prevents isolation of the metal by fusion electrolysis from a halide bath. A good survey of the metallurgy of barium calcium, arid strontium has been made recently in Light Metals (54,55).3/ Metallic magnesium (46), calcium (83), barium, and strontium (27) reduce each other's oxides. Proof of this can be found in the activation of BaO after reduction with Mg, which leads to the formation of so-called "Maquenne" mixtures (58) used for absorbing gases. However, it is impossible to extract the reduced metal- from the residue, a fact that Guntz (25) attributed to the formation of barium suboxide. There is no necessity for presuming the formation of such a compound, as it has boon established that in the reduction there is always formed an alloy of the alkaline-earth metal with the magnesium, which is capable of producing hydrogen when brought into contact with water. The reduction of alkaline earth-metal oxides with aluminum was observed by Mallet (57) in 1877, but recent investigations have shown that the end product of the reaction is an alloy of aluminum with the alkaline earth metal (1,2). Silicon also has been suggested as a reducing agent, and the results obtained are the same (84,85).

Jan 1, 1945

By C. Iglesias

Innovation in the tilemaking ceramic industry is stressing properties like powder flowability, ability to toughen green tiles, so turning technological requirements of ball clays ever stricter in terms of plasticity, dispersion in water, rheological behavior, workability in the green state, refractoriness and firing colour. Technological performance of ball clays was improved by taking as benchmark the highest quality raw materials on the market. The mineralogy, plasticity, methylene blue index and ceramic response of the Patagonian ball clays are analogous to those of European clays, but improvement is needed to approach the highest quality materials. On this basis, the Frente A, Super, Puma, and Lote 8 deposits were selected and their characteristics enhanced by additions of highly plastic and white-firing corrective clays targeted on the benchmark. Porcelain stoneware formulations, containing improved ball clay mixes, were experimented at both laboratory and industrial scale. The improved ball clays behave like the best raw materials currently used, although modest changes occur in the mechanical properties, water absorption and whiteness of the fired products.

Jan 1, 2010

By Allan J. Clark

This paper, describing the milling practice of the Homestake Mining Co., is one of a series being prepared by the Bureau of Mines. The author acknowledges the assistance of T. G. Chapman, one of the consulting engineers of the Bureau of Mines, in arranging this paper for publication.

Jan 1, 1931

By Michael MacMillan

AI is already changing how mining companies are seen, judged, and trusted. This paper discusses “reputation engineering,” a structured way to build trust in a world where AI systems summarize and evaluate everything a company says publicly. Using mining examples, emerging AI search trends, and real communication work, the paper explains why the next 12–18 months are a crucial window for action. It also provides a practical framework to help mining companies improve their visibility, accuracy, and consistency across both human and machine channels.

Feb 22, 2026

By James M. Link

A program was initiated tinder sponsorship of the U. S. Bureau of Mines to investigate pipeline behavior of raw and spent oil shale slurries. Slurries were recirculated in pipeline loops with 150-mm and 200-mm diameter horizontal test sections and a 150 -mm diameter vertical test section. Slurry concentrations from 10 to 60 weight percent were investigated. Critical and deposition velocities were observed. Head losses were measured at various velocities. Rheology measurements were made on representative homogeneous samples from the pipeline. From these data, pipeline energy requirements were predicted by computer and compared to pipeline data. Computer programs were also used to analyze pipeline data for two flow models: 1. Heterogeneous flow regime for coarse, settling slurries 2. Homogeneous flow regime for nonsettling suspensions The economics of slurry transport of raw and spent shale were examined. Cost estimates encompassed a range of pipe diameters to transport a wide range of throughputs of both raw and spent shale. Similar estimates were made for conveyor belt systems to provide a valid cost comparison. Economic comparisons are valid in a general sense, but a specific study must be made to determine the cost advantages of hydraulic transport for a given mine.

Jan 1, 1977

By I M. Turnbull

QMAP (the Quarter Million Mapping Programme, 1:250 000 scale) is a geological mapping programme which will build a digital geological database of the whole country and publish maps and books to document it. The programme was established in 1993, following a recommendation by a review panel appointed by the Ministry of Research, Science & Technology, and is funded by the government, from the Public Good Science Fund. The relevance and fundamental value of QMAP lies in the greatly improved geological knowledge it will provide for researchers and other end-users of geological information.   QMAP research involves assessment of previous work, field and laboratory investigations in key areas, and data storage, manipulation and publication using Geographic Information Systems (GIS) computer technology. The QMAP digital database of New Zealand geology will be completed by 2006, as will the series of 21 full colour printed geological maps and accompanying explanatory texts. Two are already completed and published (Kaitaia and Dunedin), and six other projects are well advanced.   QMAP information will also be available in digital form. Next year we hope to expand the scope of the programme to cover the reconciling and linking of many other earth science databases to QMAP, because we believe this will create a powerful research tool. The intention is to develop internet access to the databases, to make the information publicly available.

Jan 1, 1997