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By Thomas C. Atchison, James J. Olson

INTRODUCTION Technologic progress depends on new and innovative ideas, the practical application of these ideas, and finally as the technology is developed and demonstrated, the engineering improvement or replacement of existing capabilities. In many areas the new ideas, although known, are not immediately put to practical use in all applicable fields. Good technologic forecasting for research and development within the excavation field coupled with adequate technology transfer is necessary to ensure timely application of innovative ideas to remove bottlenecks in the total system. The purposes of this paper are (1) to show the potential ability of technologic forecasting to meet future demands in rapid excavation through the acceleration of excavation rates by research and development in several related technologic fields, (2) to provide a brief review of the initial development of the ARPA (Advanced Research Projects Agency) Rock Mechanics and Rapid Excavation Program, (3) to draw attention to the research projects completed or underway in the FY 1970-1972 ARPA program and explain where information or program results can be obtained, (4) to summarize the progress and accomplishments of applied research contracts in the rock disintegration element of the ARPA program, and (5) to discuss the research directions planned for the remaining years of the program. The Advanced Research Projects Agency (ARPA) is a group within the Defense Department responsible for conducting basic and applied research and development for advanced projects assigned by the Director

Jan 1, 1997

By S. A. Saki, J. F. Brune

"INTRODUCTION Longwall coal mining leaves large areas where the coal has been made removed and the roof rock strata collapse, forming a zone of broken rock rubble called the gob. Figure 1 shows a typical longwall gob area along with the gate roads. The ventilation pattern for progressively sealed longwall panels follows a simple “U” pattern where fresh air is coursed inby to the headgate, flows along the face and exhausts through the outby tailgate as shown in figure 1(a). An important variation of this pattern is the back return (BR) arrangement where the exhaust air from the face is drawn inby and around the nearest open cross cut before it turns in the outby direction towards the exhaust fan. Figure 1(b) illustrates the use of back return. This arrangement moves the point of low pressure from the tailgate corner up to 60 m inby and thus maintains fresh air in the tailgate region that could otherwise be contaminated with gob air.The gob area may contain remnants of unmined coal or parts of overlying coal beds that continue to release methane, eventually filling the gob area with methane in concentrations far above the explosive range of about 4.5 to 15%. Many gob areas must be equipped with gob ventilation boreholes (GVBs) to extract methane, and GVBs often exhaust methane at concentrations from 50% to 90% (Saki, 2016). Due to oxidation processes occurring in the gob, the oxygen content is reduced to a low level, with nitrogen and CO2 making up the major remaining components of the gob atmosphere. FORMATION OF EXPLOSIVE GAS ZONES IN GOBS Since the longwall face area is ventilated with fresh air below 1% methane and the face and gob areas are not separated, an explosive fringe will form where the methane content lies within the explosive range and oxygen content remains above 12%. Figure 2 shows a typical development of such an EGZ. This figure is based on a computational fluid dynamics (CFD) model developed by CSM researchers to analyze gas concentrations and flow patterns in longwall mining. Figure 2(a) shows the formation of EGZ in the gob with a U type ventilation scheme, where EGZ lies right behind the shields in the tailgate corner. Figure 2(b) shows the formation of EGZ in the gob combining U type ventilation scheme with BR, where EGZ is pushed away from the face deep into the gob. The CFD modeling parameters and boundary conditions have been verified with field data from two cooperating, active longwall mines (see Worrall 2012, Marts 2015, Gilmore 2015 and Saki 2016). Other mine geometries, methane inflow rates and gob permeability distributions can be modeled to establish representative gob atmospheric conditions. Two GVBs were operating in the model, extracting 0.165 m3/sec each. The methane in the working areas and returns was kept below 1%. Methane flowing into the model from a rider coal bed above the mined seam was at the rate of 0.55 m3/sec."

Jan 1, 2017

By B. Waquet

The genesis of a hydrothermal subsea mound, by chimney debris heaping and mineralizing fluid circulating upward, induces a vertical maturation gradient. Connected porosity is easy to measure and, after mineralogical evidence, can be use as a maturation index. Thus, to understand how a rock property evaluates with maturation, it is possible to plot it against connected porosity. Results are that uniaxial compressive strength, Young's modulus, and in a lesser certitude tensile strength, abrasivity and hardness, increase very weakly with maturation until a maturation threshold (equivalent to a connected porosity equal to 0.2), and rocket to much higher values after it.

Jan 1, 2011

By Gunter Zimmermeyer, Hartmut Eicker

Radon in the Environment Radon, as a natural nobel gas, can be detected nearly everywhere in the environment as a decay product of ubiquitous uranium. As it is emanated from soil and rocks measurable concentrations have been found at the surface of soils and in even higher concentrations in enclosed spaces like, for example, mines and buildings. While above soil surface activities caused by radon have been found in an order of magnitude of up to 1 pCi/l (Weigel, F. 1978), concentrations in enclosed spaces and mines are higher because of the lack of atmospheric circulation. Beside air circulation the relevant figure depends on the Ra226-concentration in the surrounding rocks or building material, as well as on emanation coefficient and the diffusion coefficient. While representative Rn222concentrations in well ventilated buildings are reported to be in an order of magnitude of 1 pCi/l maximum values up to one order of magnitude higher have been found in badly ventilated brick buildings (Ettenhuber, E., Lehmann, R., Clajus, P., 1978) (Aitken, J.H., et al., 1977). Just now it was stated that the reduced air circulation due to German legal regulations on energy conservation will increase radon exposure of the public considerably (Jacobi, W., 1979). Radon in Mines Radon exposure of workers is, of course, a matter of concern in uranium ore mines where relatively high concentrations of the uranium to be mined are present. Measures to protect workers' health have been implemented, based on experience on dose-effect relationship. They serve to meet exposure standards by limiting inhalation of radioactive particles, in reducing radon concentrations or in limiting working hours. Both improved measuring devices and capacity as well as the lower discrimination threshold enable to measure radon concentrations in other mines, e.g. in coal mines. It is known that radioactivity in coal is small compared with that in other minerals and even soil, rocks. Nevertheless, radioactive elements were identified in coal and so the question was whether the concentrations of radon in coal mines might be a subject of concern. The problems encountered when measuring radon in coal mines are described below, as the measuring device has to be flame proofed which is an important additional requirement. Measured radon concentrations in British coal mines have already been published (Duggan, M.J., Howell, D.M., Soilleux, P.J., 1968 (Dungey, C.J., Hore, J., Walter, M.D., 1978). The authors found concentrations of up to 14 pCi/l in Cornish mines. In most cases the values were in the order of 2 pCi/l. These results were consistent with measurements reported from U.S.-coal mines (Lucas, H.F., Gabrush, A.F., 1966). Such concentrations of radon were not considered to represent a hazard for British miners (Ogden, T.L., 1974). In Germany, too, first measurements have been carried out in five coal mines in the Saarland in the 60's. Air samples were taken at different places in the coal mines, dried, fed to an ionisation cell and measured by a device including reference cells. Samples taken at ventilated places showed radon concentrations consistent with the lower British results. They all kept within the standards of the first German regulation on protection against radiation. Measuring the radon daughters was renounced because of the relatively low radon concentrations and the requirements for flame proofness in coal mines. Moreover, it can be ascertained that because of the effective ventilation the disequilibrium factor between the decay products and the radon concentration remains far below the value of one (Muth, H., 1978) (Keller, G.). In 1979 the committee on mine safety and health protection in coal and other mines of the EEC proposed to have measured and evaluated radon concentrations in European coal mines to find out whether they complied with international standards. Great Britain and Germany agreed to this proposal and by commissioning such measurements to scientific institutes complied with the request to harmonize the methods used. In the Federal Republic of Germany, e.g. Westfälische Berggewerkschaftskasse (WBK) and Staatliches Materialprüfungsamt; Dortmund (MPA) were requested to carry out the measurements in coal mines of the Ruhr coalfield whereas Saarberg Interplan was responsible for the Saar coalfield. The WBK measurements are reported in later paragraphs.

Jan 1, 1981

By Edmundo Tulcanaza

Increasing exploration costs and the need to reduce the time-frame from exploration to production presently demand formalized procedures to assist exploration planning and reserve analysis. Exploration planning is basically required to select the most cost-effective drilling/sampling program, and to flag the needs for data of greater relevance and reliability. Reserve analysis is necessary to determine the sensitivity of grade-tonnage relations, and to clarify the economic implications of mining when alternative technical choices are to be considered.

Jan 1, 1982

By Rodolfo V. de la Cruz

The broad front concept is based on the principle that gasification can be achieved more efficiently and completely from a plane broad combustion front in contrast to other geometries obtainable with current methods of gasification. By restricting combustion to a plane broad front, the ideal condition for gasification is achieved. A plane broad combustion front can be developed in coal by initiating and propagating combustion from the walls of an oriented channel and collecting product gases from another similarly oriented channel. Flow will then be directed along the highest permeability of the coal bed, the available cross-sectional area for fluid flow is substantially increased and, more importantly, the increased flow will be uniformly distributed throughout the whole mass of coal. The success of the method is greatly dependent on how well an initial and rigorous permeability survey and associated corrective measures yield a well-characterized coal bed. To maintain uniform reaction rates, the advance of the combustion front is located with pressure- or mass flow-transducers. These sensors are then connected to servo-controlled mufflers for controlling segments of the fire front which are advancing ahead of others. Finally, the development of the concept to overcome problems of roof collapse, reactant and product gas leakages, and water invasion are briefly summarized.

Jan 1, 1976

By J. R. Walls

The United States potash industry had its beginning in the early Colonial days. Potash was initially manufactured by leaching of hardwood ashes in large iron pots. Production of potash was recorded as early as 1631 in New Hampshire, and in Maine a few years later. According to the census of 1850, the production of potash was America's most thriving chemical industry and, at that time, 569 plants were reported producing potash from wood ashes. Interest in potash was so great prior to the 1800's that the very first United States patent, signed by George Washing- ton, was granted for the production of potash on July 31, 1790. A new era for the production of potash began when potash was discovered by the analysis from a brine well in 1839 near Stassfurt, Germany while exploring for salt. The predominant use of potash at that time was in the chemical industry rather than agriculture. The discovery, by Justice von Liebig in about 1858, that potash salt contributed greatly to the essential plant food in soil opened up an enormous potential market for a suitable potash material.

Jan 1, 1985

By F. L. Wilke

Bong Mining Co. Ltd. in Liberia, West Africa, operates an iron ore open pit some 60 miles northeast of Monrovia. The production is at present about 40,000 t/d (metric tons/day) from which about 18,500 t/d concentrate with 65.5% Fe is produced. The ore waste ratio is about 1: 1.5 to 1:2. The technical layout and the equipment are very similar to those in many modern open-pit operations as described by Jacobs and Thomson (1967). As described by Lersch in detail (1966), the deposit is a very irregular one. The quality of the ore changes within very short distances with regard to both physical conditions (hardness) and chemical properties. Very soft and very hard ore as well as high-grade and low-grade ore are found adjacent to each other. In addition, there are enclosures of sterile rocks. For the purpose of identification and production scheduling, 12 different types of ore are distinguished.

Jan 1, 1979

By A. Iordanidis

Mining activities have recently been taken place in Vourinos mountain, northern Greece, exploiting the so-called ?olivinite?. A representative sample was collected from this mining area. Mineralogical analysis was conducted using X-Ray powder Diffraction (XRD). A thin section was prepared and analyzed under optical microscope. X-Ray Fluorescence (XRF) was employed for the chemical analyses of major, mi-nor and trace elements. Environmental Scanning Electron Microscopy coupled with energy dispersive x-ray analysis system (ESEM-EDX) was also applied for the characterization of the sample. Forsterite (Mg-rich olivine) and enstatite (Mg-rich orthopyroxene) were the main mineral phases determined by XRD, with a 56% and 44% content respectively. Trace amounts of chromite spinels were also determined. Based on this characterization, the industrial rock proved to be a hartzburgite (a type of peridotite in petrological terms). Optical microscopy and ESEM-EDX provided similar observations and confirmed the above-mentioned results. XRF revealed a composition of 43.31 MgO, 44.25 SiO2, 9.98 Fe2O3, 1.40 CaO, 0.67 Al2O3, 0.22 MnO, 0.01 TiO2 and negligible amount of LOI (<0.1%). Trace elements with high concentrations were Cr (2678 ppm) and Ni (2044 ppm). The comprehensive characterization of this mining product suggested the suitability for various uses, such as refractories, foundry and slag conditioner. Additional experiments are being carried out for environmental applications, e.g. wastewater treatment.

Jan 1, 2006

By Gerald C. Smith

Carlin Gold Mining Company is a wholly owned subsidiary of Newmont Mining Corporation and is located 76 kilometers north west of Elko, Nevada. Multiple bench open pit mining methods are being used to mine 24.5 Mt of ore and waste per year. Mining started in 1964 and up through 1983 Carlin has mined 138 Mt of ore and waste and has milled 13.8 Mt of ore. Selective mining of carbonaceous and oxide ores together with a good grade control program have been key factors in the success of the operation. This paper will present the raining methods and the mining equipment being utilized to make Carlin Gold Mining Company a very profitable operation while mining and milling low-grade gold ore.

Jan 1, 1985

By A. Bruynesteyn

I would like to talk to you today about microbiological leaching or, the solubilization of metal values due to the action of Thiobacillus ferrooxidans. Bacterial attack of sulfide minerals has been going on for centuries but only recently was it discovered that the acid and iron often found in coal mine drainage is produced by bacterial action on the iron sulfides in the coals. Not until 1950 was it proven that bacteria were playing a role in the dump leaching of sulfide ores. B. C. Research became involved in microbiological leaching in 1955 while examining mine drainage from the copper-zinc mine at Britannia Beach, north of Vancouver. Since 1955, B.C. Research has maintained a continuous re¬search program on microbiological leaching which, due to its applied nature, was put under industrial sponsorship in 1962. Most of the information pro¬vided in my talk today has been gathered under this sponsored research program and I would like to express our appreciation to the many sponsors who have made our work possible.

Jan 1, 1970

By R. V. Ramani

In this paper, the application of the concepts of reliability engineering to the evaluation of longwall system performance is illustrated with data from an operating longwall face. A number of cases are analyzed to highlight the impacts of longwall equipment, geological conditions and outby haulage on systems reliability and availability.

Jan 1, 1988

By R. I. Yano

Analyses of trace elements in bulk ores and in chalcopyrite and other ore minerals from porphyry copper systems worldwide, including skarns and breccia pipes, reveal some key factors regarding byproduct critical elements. Petrographic and scanning electron microscope analyses combined with a laser ablation inductively coupled plasma mass spectrometry technique developed by the USGS on selected ores from the Mackay-Stanford Ore Deposits Collection suggest that selenium occurs as atomic substitutions in sulfides, particularly pyrrhotite (up to 430 ppm) and chalcopyrite (up to 300 ppm Se); tellurium occurs predominantly as less-than-five-micron-sized inclusions of bismuth-tellurium minerals in other ore minerals, particularly chalcopyrite; cobalt and nickel are locally enriched in pyrite (up to 7800 ppm Co and 9100 ppm Ni); gallium is locally enriched in magnetite (up to 83 ppm Ga); indium and silver are locally enriched in chalcopyrite (up to 890 ppm In and 770 ppm Ag); cadmium substitutes for zinc, particularly in sphalerite (up to 4100 ppm Cd). There is considerable variation, both between and within individual deposits, in both selenium and tellurium content in these copper ores, ranging from 0.6 to 148 ppm Se and 0.09 to 64 ppm Te. Indium tends to be high in copper ores that are also enriched in silver. At current prices, many of these elements are sufficiently enriched to warrant investigation into metallurgical recovery as byproducts of the major elements.

Feb 27, 2013

By S. W. Thomas

One of the most difficult tasks associated with placer mining is the sampling of the deposit. More placer projects have failed due to inaccurate assessment of the reserves than to any other reason. Within the realm of placers, those containing valuable minerals with a high unit value .are more difficult to sample than those with larger bulk, lower unit value minerals. Some items to consider when sampling a placer deposit are as follows: A) A relatively large size sample is needed for accurate valuation of the ground being tested. Placers are composed of many sizes of gravel which makes a representative sample difficult to obtain. B) When sampling placers for high unit value minerals such as gold, any error in mineral content of the sample will be magnified in the calculation of reserves.

Jan 1, 1985

By W. R. Reed, W. J. Archer, A. B. Cecala, J. D. Potts

The U.S. National Institute for Occupational Safety and Health (NIOSH) uses light-scattering real-time dust monitors (nephelometers) in its research to develop dust controls to reduce respirable silica dust overexposures in miners. Recently, the model 1500-pDR, an active nephelometer (i.e., with cyclone and pump configuration), was introduced by Thermo Scientific. Testing was completed to ensure compatibility with the metal/nonmetal mine dust personal sampling unit (M/NMDPSU). Results of testing demonstrated that gravimetric concentrations measured from the 1500-pDR are comparable to the gravimetric concentrations measured using the M/NMDPSU, without need for correction, under commonly observed dust loading conditions.

Jan 1, 2012

By B. Kolonja

A SIMAN and CINEMA PC-based simulation model was developed to simulate and animate the truck-shovel operations of surface mines. The model is capable of simulating one mathematical dispatching strategy using linear and dynamic programming and six heuristic dispatching strategies. Data were collected from an actual operating mine through time studies and analysis of historical records. The statistical analyses were performed and appropriate theoretical distributions were fitted for various time events in the truck-shovel work cycle. The model was then applied to study overall impact of these dispatching strategies on constrained and unconstrained mine productivity. The simulation/animation model developed in this study seems to be an efficient planning tool for choosing optimal fleets and finding an &apos;optimal" dispatching strategy to produce an equilibrium between "the quality and quantity of production.

Jan 1, 1993

By Steven T. Mitchell

The introduction of Vertical Crater Retreat (VCR) Stoping at the Homestake Mine in Lead, SD, constitutes a major advance in Homes take Mining Company&apos;s efforts to improve productivity and reduce costs through underground mine mechanization. The work to date indicates that Vertical Crater Retreat Stoping is one of the safest methods of underground hardrock mining today, and is competitive with all other forms of stoping in terms of cost and productivity. Homes take anticipates that VCR stoping rill account for approximately 30% of the total mine production in 1980.

Jan 1, 1980

By W. M. Pytel

A simplified two-dimensional model to analyze time-dependent load distribution and surface subsidence associated with longwall mining geometries is described. The model is based on the theory of beams resting on inelastic foundations and includes visco-elastic behavior of immediate floor strata, non-linear behavior of coal pillars, elastic behavior of face supports, and visco-elastic behavior of the overburden strata. The relative importance of the different variables affecting the performance of longwall mining geometries from ground control point of view is also analyzed. The model has been validated for field observations from one Illinois longwall mine.

Jan 1, 1986

By Dmitriy A. Malovichko

The general theory for the description of seismic sources is briefly discussed. The effect of excavations on seismic radiation is considered. Expressions for seismic source mechanisms in terms of the geometrical and mechanical parameters of source processes are provided for the following cases: fault slip and shear failure in a confined environment, dynamic stress fracturing around a tunnel, rock fall, landslide and sudden subsidence. A classification of seismic events in mines based on source mechanisms is introduced. The classification separates blast-, slip- and crush-type events. Various approaches of analysis of source mechanisms involving forward modelling and inversion are discussed. The following examples demonstrating the utility of source mechanisms in mining are presented: forensic analysis of damaging seismic events, assessment of the increase in the depth of failure for dynamic stress fracturing around tunnels and its duration, examination of the rockmass deformation regime, assessment of deformation around tunnels using crush-type events, identification and parameterisation of weak geological structures, stress inversion from slip-type events. Finally, the requirements for seismic data to ensure high quality source mechanism solutions are briefly reviewed and future challenges in the interpretation and utilisation of seismic source mechanisms in mines are speculated on.

Apr 26, 2022

By Jamal Rostami, Tom Iseley, Saleh Behbahani

Tunnels and underground infrastructures assets, like all assets, deteriorate with time. At some point, they reach the end of their useful life. Therefore, frequent inspections, higher levels of maintenance, and rehabilitation are needed to address loss of life and safety concerns. The repair cost of tunnels will increase if maintenance of tunnels is not satisfactory and timely. Historically, tunnel inspections have primarily relied on visual and manual procedures. Due to their time-consuming nature and susceptibility to human error, there is a demand for alternative automated techniques that can enhance efficiency and reliability in tunnel inspection. By utilizing a tunnel scanning system, such as laser scanner and thermography, or photogrammetry system, tunnel inspection cost, time, and personnel can be reduced. The goal of this study is to utilize deep convolutional neural networks (CNNs) for automated identification of defects in tunnel lining inspection. This paper presents a framework to classify two types of defects in tunnel lining (water leakages and cracks) using CNNs. The CNNs were trained and tested using 4,608 images. The Precision, Recall, and F1 Score were each 99.6%, confirming the viability of this approach in the automated defect identification in tunnel lining.

Jun 23, 2024