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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 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 K. Nagata, T. Kawashima, S. Tejima

The expanding volume of maritime coal transportation is intensifying the problems concerning large vessel service, port construction, trans-shipment, and environmental control. The major problem is the shipment of coal. Customary methods for bulk transfer must be improved and new systems developed. Slurry unloading has a key role in the new systems. This report reviews progress in slurry transportation research that has been done in Japan since the 1960s, when large-scale experiments for domestic transportation were done. Experiments on the effects of vibration on the slurry cargo and on reslurrying are focused on.

Jan 1, 1987

By T. C. Bibb

Longwalls using shearers in seam heights of less than 1.2 m (48 inches) are relatively rare in the U.S. Westmoreland Coal Company is currently operating a shearer-equipped longwall at a cutting height of 1.17 m (46 inches) in its Bullitt Mine. This face has averaged 2795 metric tons/day of operation since its startup on April 3, 1984. Longwall productivity in thin seams is substantially impacted by equipment reliability and availability of useable working room for travel and access. This paper addresses the design criteria used in selecting this face equipment, with the goal of maximizing these two parameters. Equipment discussed includes shearers. face conveyor, shields, stageloader, and emulsion system.

Jan 1, 1985

By Erik Vlot

"The mining industry has recognized the advantages of high density backfill or ‘paste’, which is typically pumped with a hydraulically driven piston pump. Due to the discontinuous flow of this type of pump, pressure pulsations can occur in the discharge line. Pressure pulsations are an undesired phenomenon in pumping installations for a number of reasons that include: damage to the pumping system; piping and supports; disturbing noise levels; and even safety risks for operators and maintenance personnel.This paper describes an advanced system on the GEHO® piston pumps, which will prevent virtually no pressure pulsations from occurring, rather than merely reducing the already existing pulsations.INTRODUCTIONThe first GEHO® hydraulically driven piston pump was developed in the mid-1970s. It was an industrial design pump designed to operate in the high-standard industrial environment with regards to operating hours per day, duties, maintenance and lifetime of the pump and spare parts. This type of pump has a proven track record and has been further developed for the type of applications that we are describing today. The special feature of this pump type is its ability to pump extremely viscous slurry with solids content of up to 90% by weight, at high pressures. Typically, in the mining industry, this pump is used for tailings transportation, with a focus on mine backfill and is often referred to as a paste pump.In the 1980’s the hydraulically driven piston pump made its entry into the application of mine backfill, thanks to the high discharge pressure capabilities enabling the mines to pump higher density (i.e. higher solids concentration) slurries and pastes over longer distances.Part of the ongoing development was (and still is) the increase in discharge pressure and flow capacity to comply with the ever growing demands for high power piston pumps. In line with the technological developments and increase in performance duties, the popularity of this pump type increased significantly and many other industrial applications have discovered the benefits of this pump type.Together with the increase in pump discharge pressures and flow capacities the effect of an undesired phenomenon also increased: the phenomenon of pressure pulsations. Before we explore this subject in more detail it is important to first understand the design and the characteristics of a hydraulically driven piston pump."

Jan 1, 2017

By Someswar Kesh, Gavin J. Faulkner

Introduction Powered supports in longwall mines essentially operate under two conditions: 1. Static (non-working) 2. Dynamic (working) There is a variety of static conditions which may exist in a mine. These may include a temporary stoppage of work for a few minutes or stoppage of work for days because of strikes or lack of demand for coal. Studies on pressure behavior were made during brief stoppages of work (few hours) as well as a long stoppage of work (two weeks). In dynamic conditions, the pressure variation on supports is expected to follow a certain pattern. However, in many cases that does not happen. Pressure-time characteristics of each leg of the supports were studied. This paper discusses the research findings of the studies made on powered support pressure behavior under both static and dynamic conditions. Studies on Pressure Variation in Static Conditions It has been noted (Brenner et a1.,1975) that the pressure distribution on mechanized longwall faces is random in nature and changes with time and position along the face. Figure 1 and Figure 2 show the distribution of support pressures for the front left leg of supports in two different mines. In both the cases it can be seen that the variation of the support pressures along the face is indeed absolutely random. However, the nature of randomness in both the cases is very different. The data in Figure 1 (Mine 1) is much more random than the data in Figure 2 (Mine 2). This can also be seen from the standard deviation of the data (81 26 Pa versus 4000 pa) . By comparing the results of ten other sets of data the same conclusions can be arrived at. Since it was found that in Mine 1, the pressure on support legs was extremely random, batches of ten supports each were taken and the mean pressure plotted. This mean pressure line is shown in Figure 1. It was expected that this would smooth out the variation due to individual props and reveal a better picture of the support pressure distribution. For the case cited, the standard deviation is lowered to 5043 Pa from 8126 Pa which indicates that, on an average, the supports tend to take loads more uniformly, however for individual support legs the load on the supports is very random. The significance of this is that, if the supports are selected on the basis of theoretical load calculations alone (based on the roof block concept or some other concept), only the mean value of the support load required will be known. In the case of a pressure distribution with a high standard deviation, some supports selected on the basis of mean value will fail, while others will be supporting low loads. Hence, for proper selection of support capacity, it is not only necessary to know the average load but also the expected nature of the distribution. The only reason why the supports are supporting the roof in Mine 1 well is the fact that the yield load is above the highest level of load attained. If Mine 2, which has a much higher average load, had the same sort of standard deviation, the loads on the individual legs could easily exceed the support load. For example, if the pressure distribution followed a normal curve and the mean pressure was 36,700 Pa with a standard deviation of 9000 Pa, it is possible that 67% of the supports will be within the pressure range of 36,700 plus or minus 9,000 Pa, or 22,700 and 45,700 Pa. Many of the supports could then exceed the yield load of 40,000 Pa. It is clear then that the mean load is an inadequate criterion for estimating support resistance. The nature of the problem is statistical and such an analysis should therefore be made as far as pressure data are concerned. Statistical Analysis of Pressure Data. In general, in longwall mining and other geo-mechanics studies, it is extremely difficult to specify the exact nature of the distribution of a variable. Under these circumstances, probability

Jan 1, 1986

By D. D. Harbuck

The U.S. Bureau of Mines investigated germanium and gallium extraction from an ore containing 0.089% Ge and 0.036% Ga. While previous researchers concluded that a reducing agent such as 502 is needed to extract germanium and gallium from such ore, this research showed that high extractions (87% Ge, 97% Ga) were possible using sulfuric acid alone, if the acid concentration were properly controlled. This control was achieved using a two-stage counter-current leach circuit. Microprobe analyses revealed that the non-extracted germanium is in solid solution with quartz, and therefore cannot be leached with 502 or sulfuric acid.

Jan 1, 1991

By Meghan M. Murphy, Derek Penrice

The Downtown Rail Extension (DTX) is principal element of the planned second phase of the Transbay Joint Powers Authority’s (TJPA) Transbay Program. When complete, this regionally critical project will connect Caltrain’s regional rail system and the California High-Speed Rail Authority’s statewide system to the Salesforce Transit Center in downtown San Francisco via a 1.3-mile tunnel. Studied since the 1970s, the DTX has now received environmental clearance, and key stakeholders are aligned on the project’s configuration and its expedited delivery. This paper describes efforts to optimize the DTX configuration and develop an informed project delivery strategy that incorporates construction industry feedback on project phasing, contract packaging, and procurement methods that accomplish the project’s budget goals.

Jun 13, 2021

By T. J. DeMull

The business of heap leaching requires accurate forecasting of metal production from the heaps. Business forecasts typically follow a format that project periodic (monthly, quarterly, or annual) product shipments based on anticipated operating results, e. g., tons of ore placed, grade of ore, and rate of leach extraction. Since revenue and cash flow are dependent on the metal production stream, forecasts of metal production are very important for project evaluation and business planning purposes. Nevertheless, production forecasts, particularly for new heap leach projects, have been prone to errors. The present paper identifies some of the pitfalls that would be encountered in preparing production forecasts for new heap leach operations and provides a checklist of considerations to assist in preparing a forecast. Also, the paper presents a case study of copper production forecasting used for the Sanchez Project, a heap leach operation located near Safford, Arizona, that is presently under development by AZCO Mining, Inc.

Jan 1, 1995

The Putnam Coal Mine, at design capacity, will be the third largest underground bituminous coal mine in the world and will feature the world's longest single flight belt conveyor. Construction is now in process; initial mining will commence in early 1969 and design capacity will be reached in 1971. I'm Jerry Workman, Assistant Mining Manager for the Coal Group of the Mining and Metals Division of Union Carbide Corporation, and I am acting as Project Manager for installation and start-up of the Putnam Mine. The Putnam Coal Mine reserves are located in south-central West Virginia and contain approximately 27,000 acres of prime Pittsburgh No. 8 coal; reserves are sufficient to support a 3.5 MM tons per year operation for over 30 years. The mine portal area is located some six miles inland from the Kanawha River. The river loading facility is located approximately 156 miles by way of river from the market.

Jan 1, 1968

By Hervé Le Bissonnais, Jean-Pierre Janin, Anne Bergère, Pierre Renier

"The most important impact on the environment of a tunnel excavation is the creation of surface settlements. Nowadays, the mechanized tunneling allows minimizing the settlements, applying a confinement pressure which counterbalances the ground de-confinement. It is thus essential to determine the correct amount of confinement pressure. In this paper, the authors present a 3D numerical study simulating the EPB-TBM excavation of a water tunnel, in the Flanders clays (north of France). Firstly, a simplified 3D simulation, based on the concept of instantaneous longitudinal settlement curve, was performed to predict the surface settlements for different values of heading confinement pressures. Secondly, the same pressures were tested by the EPB-TBM in a monitoring zone. The comparison between the prediction settlements and the measurements was very satisfactory and allowed validation of the numerical approach and the choice of the optimal confinement pressure value for a sensitive area of the project. INTRODUCTION The excavation of a tunnel can create displacements of the surrounding soil which may affect existing structures and generate unacceptable dysfunction. The development of the closed shield tunneling has permitted to reduce the volume loss generated around the excavation and consequently the surface settlements. In this case, as explained by different authors (Clough et al., 1985; Kastner et al., 1996; Mair and Taylor, 1997), the ground movements are influenced by the TBM works: the heading confinement pressure, the shield overcutting and conicity, the annular void grout injection parameters, the segment concrete lining rigidity, the consolidation of the grout. Hence, in the tunnel design, it is important to take into consideration these different processes of the excavation works to simulate correctly the tunneling process."

Jan 1, 2016

By Norman F. Schulz

The Davis magnetic tube concentrator is a laboratory machine designed to separate a small sample of pulverized magnetic iron ore into magnetic and non-magnetic fractions. It was developed in 1921 by mechanization of a test previously performed manually. (1)(2)(3)(1) No significant changes have been made in the design of the apparatus since that time. The Davis magnetic tube test continues to serve as a practical basis for judging the amenability of an ore to magnetic separation and for controlling magnetic separation plant operations. The apparatus consists of an inclined cylindrical glass tube supported adjacent to closely spaced pointed poles of a powerful C-magnet. (Figure 1). To conduct a tube test, a sample of a suitably prepared ore is poured into the water-filled tube. With wash water flowing through, the tube is oscillated to gradually reject the weakly magnetic ore particles until the desired degree of separation is attained. Both the magnetic concentrate and the tailings may be recovered for examination.

Jan 1, 1963

By Gabriele Eccher, Michele Caponero, Paolo Cucino, Roberto D’Angelis

"This paper describes the optic fiber structural monitoring system implemented for Pavoncelli Bis tunnel. The paper highlights the optic fiber sensors customization capabilities, how they smoothly fit precast concrete lining processes and TBM operations, and how a lifelong service monitoring can be achieved. An overview of readings’ evolution during excavation concludes the paper.INTRODUCTIONPavoncelli Bis is a 10 km hydraulic tunnel designed to by-pass the existing Pavoncelli tunnel which experienced severe damages during the 1980 Irpino-Lucano earthquake, in south of Italy (Barla 2009). Pavoncelli Bis excavation work commenced in 1988-90, however, when excavation approached pk. 0+583 in 1992, water percolations became more and more consistent and resulted in work suspension. The tunnel was eventually sealed at pk. 0+383, leaving a flooded section between pk. 0.383 and pk. 0+583. Work resumed in 2012 where EPB-TBM excavation was adopted to cross the flooded section and to overcome complex hydro-geological conditions in various lito-types and, in particular, in the Varicolori Clay-shales area (Figure 1).Consequently, stress evolution monitoring is extremely important during construction and during the service life of tunnel lining in clay-shales and in faults areas. In particular, the paper focuses on the monitoring system proposed for the newly EPB-TBM excavated portion from pk 0+583 onwards where optic fiber sensing technology was chosen for its reading stability and reliability in presence of water and its ability to be connected in series and remotely interrogated at kilometers of distance. FBGS OPTICAL FIBER SENSOR TECHNOLOGYFiber Bragg Grating Sensors (FBGS) are gaining increasing attention in the field of experimental stress analysis. Basically, Fiber Optic Bragg Sensors are strain-measuring devices and therefore provide many of the advantages of the well-known metal foil strain gages (Kreuzer 2007).Bragg gratings are written into so called single-mode fibers. These fibers consist of a very small inner core of 4 to 9 µm diameter and an outer part (cladding) of pure glass (SiO2) of 125 µm diameter. The difference of refraction indexes between inner core and cladding causes the light to propagate only inside the small core."

Jan 1, 2016

By Milan Yekich, Emanuele Cauda, Justin Patts, Cody Wolfe

A worker’s personal exposure to respirable dust in occupational environments has traditionally been monitored using established methodologies which entail the collection of an 8-hour representative sample that is sent away for laboratory analysis. While these methods are very accurate, they only provide information on the average exposure during a specific time period, generally a worker’s shift. The availability of relatively inexpensive aerosol sensors can allow researchers and practitioners to generate real-time data with unprecedented spatial and temporal granularity. Low-cost dust monitors (LCDM) were developed and marketed for air pollution monitoring and are mostly being used to help communities understand their local and even hyper-local air quality. Most of these integrated sensing packages cost less than $300 per unit, in contrast to wearable or area dust monitors specifically built for mining applications which have been around for decades but still average around $5,000 each. At the National Institute for Occupational Safety and Health (NIOSH), we are leveraging the power of high-volume data collection from networks of LCDM to establish baseline respirable hazard levels and to monitor for changes on a seasonal basis as well as following any application of control technologies. We have seen the effective use and advantages of monitoring live data before, during, and after events like shift changes, operational changes, ventilation upgrades, adverse weather events, and machine maintenance. However, many factors have prevented a systematic adoption of LCDMs for exposure monitoring: concern for their analytical performance, the complexity of use, and lack of understanding of their value are some factors. This contribution outlines a one-year case study at a mine in Wisconsin USA, covering the installation, maintenance, data visualizations, and collaboration between NIOSH researchers and the industrial hygiene professionals at the mine.

Feb 1, 2024

By E. E. Maurer

Kerr-McGee has operated the Ambrosia Lake uranium mill since startup in 1958. Tonnage milled per day has varied from 3500-7000 tons. The mill capacity is currently rated at 7000 tons per day. The process consists of two parallel circuits following crushing and sampling, \\lhich include open circuit rod mill grinding, sulfuric acid leach, cyclone classification, and counter-current washing circuits of sand classifiers and slime thickeners. Pregnant solution is clarified and polished by precoat pressure leaf filters prior to amine solvent extraction. Yellowcake is precipitated from the pregnant strip solution with ammonia, filtered and dried.

Jan 1, 1972

By Yongsik Jeong, Kwangmin Kim

Conventional tailings slurry contains a significant amount of water, and water management is key to ensuring the stability of a tailings storage facility (TSF). Simply reducing the water content in the slurry before discharging it from the mill could be an effective way to improve TSF water management. This study investigated the potential for using an environmentally friendly polymer as a new drag reduction agent (DRA) to reduce frictional pressure loss and also conserve water. It entailed conducting pipe loop tests to assess the polymer’s effect on pressure loss in tailings flow and then applying the test results to validate a numerical model using computational fluid dynamics (CFD). The model was also used to determine the polymer’s optimal concentrations at given solid concentrations and flow rates, its effect on energy efficiency for tailings transportation, and its potential for saving water. A case study for a mid-sized, hard-rock mine with a throughput of 50,000 t/day found that the solid concentration could be increased from 30 to 45% with no pressure loss by applying 1996 m3 of the polymer per day. Adding the polymer also resulted in water savings of 57,552 m3/day. The results of this study demonstrated the potential for using the new DRA not only to improve TSF stability but also to save water.

Jun 29, 2020

By Jeffrey A. Holcomb

INTRODUCTION The passage of Comprehensive Environmental Response Compensation and Liability Act (CERCLA/Superfund) as well as the Resource Conservation and Recovery Act (RCRA) and state laws, have placed added regulatory pressures on the mining industry. These laws which focus on the regulation of hazardous substances and wastes for the protection of the public health and welfare and the environment, present the potential for tremendous financial impacts and liabilities on existing mine operators and owners and/or potential mine operators/owners. This paper takes a brief look at these laws and presents an environmental audit procedure to identify environmental liabilities prior to mine land transactions. The environmental audit approach presented is an overview of the procedures that could be used to document, evaluate and inventory existing and/or potential environmental concerns. This audit procedure can be applied to developed or undeveloped properties and at active or inactive mining sites. REGULATORY OVERVIEW Mining environmental liabilities have been addressed in RCRA, Superfund, the Clean Air Act (CAA) and the Clean Water Act (CWA). Even though the U.S. Environmental Protection Agency (EPA) has determined that mining wastes will be treated as solid wastes under RCRA and not as hazardous wastes, these wastes could still bring about a great deal of financial liability under Superfund. The catch is if the mine wastes generated contain hazardous substances such as the heavy metals arsenic, beryllium, cadmium, chromium, copper, lead, mercury, nickel, selenium, silver, thallium, zinc and others as well as cyanide. Thus, it is not only important for a mine operator/owner or a potential mine operator/owner to know if the mine wastes generated are hazardous, but it is important to know if the wastes contain hazardous substances. Following is a brief overview of RCRA and Superfund and their potential implications. RCRA RCRA, which provides the basis for the regulation of solid and hazardous wastes, is applicable to active mining and milling sites. Within RCRA the definition of a hazardous waste is provided. This definition applies to owners and operators of mining and milling sites if the operator has stored, disposed or treated hazardous wastes on-site. If this is the case and if strict process control and waste management activities are not adhered to, environmental liabilities may be associated with the site. Superfund The 1980 Superfund law can be applicable to inactive mining sites or to inactive sections of an active facility. The provisions of Superfund call for the regulation of hazardous wastes and hazardous sub- stances disposal and release not only by the existing owner, but also for any previous owner. This concept of joint and several liability means that one party, as among many, can be held totally responsible for the costs of hazardous waste cleanup (Haller, 1987). Furthermore, liabilities under Superfund have also been applied back to past acts; thus, several mining properties, active or inactive prior to the 1980 Superfund law, are at risk of being placed on the EPA's National Priority List (NPL) for cleanup. Last years amendments to Superfund, known as the Superfund Reauthorization Act of 1986 (SARA), provided some significant developments for the mining industry. The major requirement of the amendments as it pertains to owners or operators of mining sites is that the EPA must revise its present Hazard Ranking System (HRS). This is important be- cause in most cases the primary reason for several mining sites having been included on the NPL was due to the large volume of wastes generated. As is typical at most mining sites, large volumes of low toxicity wastes are generated and the current HRS model prejudices against this. It should be noted that this provision only applies to sites that are not already on the NPL or have not been proposed for inclusion on the list.

Jan 1, 1987

By Andrew Chegwidden, Tara Wilk

Construction of Shaft 17B-1, a part of The New York City water supply system, required an excavation of approximately 38 m (123 ft) through water-bearing overburden soil and more than 152 m (500 ft) of gneiss bedrock to make a connection to Water Tunnel No. 3. Ground freezing was the specified method to provide temporary earth support and ground water control for the overburden material. The ground freezing process relied on a supplemental geotechnical investigation and comprehensive laboratory testing of the frozen soil to evaluate the potential long-term creep behavior of the soil and the elimination of a temporary lining system. This paper describes that process as well as the drilling and installation methods of the ground freezing system. Additionally, the methodical system of excavation and insulation is discussed that permitted a safe and timely excavation followed by the installation of the permanent concrete liner.

Jun 13, 2023

By R. J. Sheets

In 2009 the Gold Quarry open pit mine, located 11 km northwest of Carlin, Nevada, USA, experienced multiple large-scale slope instabilities of the upper east highwall that reduced gold ore extraction for nearly 18 months. The slope instabilities occurred within a weak, consolidated sedimentary sequence that exhibits strength characteristics that are transitional between soil and rock. Instability initiated as mining exposed the lower clay-rich sub-units of the Carlin Formation (Fm.). This deformation created preferential flow paths that allowed groundwater from the upper sandy sub-units to infiltrate low permeability clay-rich sub-units, thereby enhancing deformation of the slope toe which in turn destabilized the upper portion of the highwall. The outcome was a 160 m high slope instability that had a lateral run-out of 850 m. The effort to return the pit to ore production required both the geotechnical and hydrogeological investigations and the preliminary remediation mining activity to be concurrent. This approach required the development of detailed safety procedures and a requirement to modify the remediation design as new results were obtained. An initial challenge was to mitigate a near vertical, 90 m headscarp with blast induced, localized slope failures. Back-analyses applying numerical modeling indicated that the failure surface did not coincide with initial interpretations based on field observations; drilling results eventually confirmed this alternative failure geometry. The final remediation design incorporated shallower slope geometries and an approximately 3 Mt buttress along the base of the Carlin Formation and bedrock contact to reinforce the lower clay-rich sub-units. The outcome is a stable highwall within the Carlin Fm. following nearly ten years of repeated slope instability, and an example of the necessity to conduct appropriate geotechnical and hydrogeological studies during the early stages of a new layback evaluation or new open pit development.

Feb 23, 2014

By R. E. Doerr

The successful technical demonstration of coarse coal slurry transportation at Consolidation Coal Company's Loveridge Mine in West Virginia suggests that it is now appropriate to seriously consider this technology in other applications, especially the transport of ' coal in surface mining. Early examination indicates that coarse coal slurry transport may be highly competitive with existing haulage systems, depending on a number of factors. These factors are not yet completely defined, but certainly will include production rates, coal physical and chemical properties, terrain, soil conditions, climate, water availability and quality, availability of skilled labor and other economic considerations impacting the existing haulage systems.

Jan 1, 1983