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By Stephen Phillips, Luigi P. Gonano

Vertical circular shafts have been proposed for multiple access to high level nuclear waste deep geologic repositories. Shaft construction is a critical path item in the commissioning of a repository. Other constraints on the shaft design and construction criteria include the lack of design precedence for long term performance and the importance of minimizing rock and groundwater disturbance. A comparative evaluation of conventional and mechanized shaft sinking techniques is presented in the context of the particular geologic and design constraints. Technical and non-technical factors for blind drilling, blind boring, raise-reaming, drill-and-blast and ream-and slash methods are reviewed for typically "hard rock" and "salt" type repository sites. Appropriate shaft designs are developed, the suitability of each method to the particular requirements evaluated and construction costs and schedules determined. The explicit appraisal of the significant design factors for each method serves as a rational basis for the preliminary selection of the most suitable sinking technique for a particular set of site/design conditions.

Jan 1, 1983

By R. J. Sweigard, R. V. Ramani

G.F. Learning The paper by R.V. Ramani and R.J. Sweigard is a wonderful description of the labyrinthine web that has been spun about the mining industry by energetic bureaucrats and politicians over the past 50 years. The remedy for the problem, however, is not more of the same, but less. That may be difficult for the industry to achieve, for it is not a technical solution but a political one. And the current fervor for more detailed planning at all levels of government and private enterprise has become deeply ingrained. The authors recommend the provision of more information about mining and mineral resources to "macro" (i.e., government) land use planners. They apparently overlook, however, the already strong tendency on the part of most government land use planners to consider themselves omniscient. Thus, giving them more information about the technical problems of mining will only make them want to get more and more involved in the "micro" (private, site specific) mine development and production plans of the individual mining firm. In fact, this has already happened at all levels of jurisdiction from municipal to federal government. Examples are legion. The most effective way to ameliorate the adverse impacts of government land use planning on existing and potential mining operations is to: (1) introduce greater flexibility in the definition of land use zones by local and state governments; (2) adopt realistic and relevant ambient environmental performance standards in governing relationships between mineral land uses and concurrent or subsequent nonmining land uses; (3) allow greater leeway for economic considerations in land use decisions in contrast to the explicit legalistic approach now in vogue; (4) recognize that all minerals are not the same and that sand and gravel mining should not be treated the same as underground metal mining, coal stripping, oil field production, or in situ leaching; and (5) eliminate the notion that mining operators should be responsible for determining in detail the use of land by subsequent owners of mined land. This last bit of conventional ethic really makes no more sense than requiring the builders of every shopping center or government office complex to provide detailed plans for the use of that land when its use for shopping or government is ended. Did the builder of Ebbetts Field plan for Brooklyn after the Dodgers went to Los Angeles? Should the developer of the Bingham Pit plan for suburban Salt Lake City after the copper mining goes to Chile? The nation's mining industry must address these questions before further bankrupting itself to provide more data to planners and spending thousands of dollars per acre to create land that when reclaimed is worth only a few hundred dollars per acre. Reply by R.V. Ramani and R.J. Sweigard We thank Mr. Leaming for his valuable contribution. His views on the problems of land use planning and mineral resources are most welcome additions to our paper. As the title indicates, our paper was more concerned with the impacts of land use planning on mineral resource conservation than with the details of the planning process. On the whole, his five recommendations would be helpful for mineral resource conservation. However, we would suggest that the argument he presents for his final recommendation does not address the differences between mining as a land use and commercial or institutional uses. We believe that this difference is the crux of the issue. We share Mr. Leaming's desire to ameliorate the adverse impacts of land use planning. Possibly the most detrimental impact is the loss of mineral resources. Any development, whether mineral or community, that does not give proper consideration to other resources can result in permanent loss or sterilization of resources. With proper planning, some of these losses can be avoided. As our paper indicated, one factor that limits the consideration of mineral resources, and ultimately leads to their sterilization, is the generally inadequate levels of resource characterization and understanding of the unique nature of mineral resources and mining operations. The last point raised by Mr. Leaming is also important. In terms of reclamation and land use planning in mining districts, we certainly do not advocate spending more than what the results are worth. The main thrust of the paper was to explore the avenues for conserving the mineral resources so that, at some appropriate time, the issue of mining and reclamation can still be addressed.

Jan 4, 1985

By G. G. Gold

A leach pad’s fluid flow characteristics greatly affect the recovery of metals from heap leaching. However, because there are other factors such as particle size distribution, application rate and method, and chemical reactions to consider, mining companies often overlook potential problems associated with fluid flow until it is too late. In an effort to better understand the dynamics of fluid flow in leach pads, a series of experiments were preformed using temperature probes. A model leach pad was set up using a particle size distribution, fluid application rate, and application method common to modern leaching methods. Variable water temperatures were applied in succession and data gathered from the three dimensional grid of temperature probes built in to the model. Current work is analyzing these data along with visual observations of the model, computer simulations, past mining experiences, and other related research, in an attempt to develop a low cost test that could be performed prior to large scale leaching to determine the fluid flow characteristics of a particular ore. This paper will summarize the work and findings to this point as well as suggest areas of additional related research.

Jan 1, 2004

By B. P. Spigarelli

To meet the growing need for CO2 capture and storage technology, Michigan Technological University is researching CO2 capture and storage using carbonate solutions. The objective of the present study was to increase the absorption rate of CO2 into the carbonate solution without reducing the absorption capacity of the solution. This approach used a polypropylene glycol methyl ether (PPGME) as a surfactant to chemically alter the gas bubble size. Experiments were conducted to study the absorption rate of CO2 at varying surfactant concentrations of 0, 0.12, 0.24, 0.36 and 0.48 g/L. Results showed that as the concentration of surfactant increased in solution, the absorption rate also increased. The CO2 absorption rate increased from 3.45 mmol/min CO2 at 0 g/L PPGME to 3.92 mmol/min CO2 at 0.48 g/L PPGME. This amounted to a 14% increase in the CO2 absorption rate with no decrease in absorption capacity of the solution.

By Robert L. Marovelli

The major mining health and safety problems of concern to United States Government and private industry researchers in 1981 included the difficulty experienced by longwall operators in complying with the Federal 2 .0-mg/m3 respirable dust standard, the accident rate associated with falls of ground and materials handling hazards, and the upsurge in the incidence of disasters after the steady decline in recent years. Although the many mines and manufacturing companies involved in the research projects to be described are not specifically identified, it is important to note their significant involvement. This is not by way of acknowledgement, but rather to establish that these projects, using mostly Federal funds, represent close cooperation between the U.S. Government and the mining industry. The ongoing work to be described on the development of critical longwall dust control technology is a classic example of Government-industry participation through the phases of problem identification, planning, cost-sharing, and implement at ion.

Jan 1, 1982

By D. F. Machuca-Mory

A change of support model consists of a procedure to change a stationary histogram at a small data scale to represent a larger scale; typically a distribution of sample drill-hole data is changed to represent a chosen selective mining unit (SMU) scale. Most grade variables average arithmetically. Thus, the mean stays the same for different scales, and the variance changes according to well-established theory using average variogram values. The longstanding challenge has been to predict how the shape of the histogram changes. The discrete gaussian model is widely used because it appears reasonable and introduces few artifacts; there are no artificial minimum/maximum values and the target mean and variance are reproduced exactly. The resulting distribution shape, however, is strongly dependent on a multivariate gaussian distribution. The authors generalize the approach by taking advantage of a property of the isofactorial model, which allows one to specify where the random function falls on the spectrum between a low-entropy mosaic model and a maximum-entropy diffusion model. A measure of dissemination (MD) is computed using a ratio of the madogram and the variogram. The change of support algorithm is developed that uses a variable measure of dissemination (VMD) that is easily calculated and fit to data from the deposit. The resulting VMD change of support model is very flexible to represent different mineralization styles encountered in practice; global predictions of recoverable reserves are more accurate and decision-making is improved. A number of real examples are shown to demonstrate the approach.

Jan 1, 2008

By R. B. Elver

The level of steel consumption per capita is one of the principal indicators of a country's standard of living. It is no coincidence that the materially advanced nations possess viable iron and steel industries to provide a reliable and economic source of steal for the manufacturing industries. No other metal is as dominantly important in manufacturing as steel. The blast furnace - steel furnace complex based on coking coal, ferrous scrap and iron ore - continues to be the principal steel-producing method. Less important is the electric furnace method based on scrap, In recent years, there has been considerable interest in the many direct reduction processes that are not dependent on coking coal but usually produce a product for further refining in steel furnaces. No matter which series of processes are used, iron ore is essentially the only source of virgin iron units. Thus, to such a vital and capital-intense industry as steel, access to a relatively inexpensive, long- term supply of iron ore is essential.

Jan 1, 1964

Where space is limited, as it is throughout most of the northeastern United States, new construction either takes place high above street level, or below it. In Lower Manhattan, NY both kinds of expansion can be found in abundance. That is good news for the nearly 200 attendees at the George A. Fox Conference, presented by the Underground Construction Association (UCA) of SME at the Graduate Center, City University of New York, on Jan. 30. Among the many projects taking place in Lower Manhattan?s massive trans-formation process, are expansions to the city?s vast underground network of subways and other tunnels. ?New Yorkers either live on the ground or below it,? said keynote speaker Charles J. Maikish while explaining how an attempt to build above street level walkways never caught on in the city. Maikish is the executive director of the Lower Manhattan Construction Command Center. His job is to oversee the $22 billion project that will transform the island by 2010. From the construction of Freedom Tower at the site of the fallen World Trade Center buildings, to the expansion of the Second Avenue Subway, the extension of the East Side Access, No. 7 line, the new trans-Hudson line and numerous waterway tunnel expansions, including City Water Tunnel No. 3, the task Maikish is charged with is a huge one. He is primarily responsible for coordinating the scheduling and staging of the overall rebuilding plan, along with the day-to-day coordination of construction work down-town. He places particular focus on mitigating impacts on the environment and mobility, maintaining and improving access and alleviating congestion of any kind related to construction. At the time of the Fox Conference, there were 59 projects under way in Manhattan. All of those projects need things like concrete and steel delivered to sites in very tight working environments. And some need the equipment in even tighter spaces. ?This is not just about the recovery of Lower Manhat-tan (from the 2001 terrorist attacks) but this is a plan to restore it and to maintain its integrity,? said Maikish. ?I think that is the appropriate response to the terrorist attacks.? When Freedom Tower is completed, it will stand 541 m (1,776 ft) about the skyline. That will be a strong statement to the world about America?s strength. But it is the work that takes place much lower that was of interest to the conference attendees. On this respect, Maikish said Manhattan?s efforts below ground aim to provide relief to the city?s street level congestion and to make sure Manhattan ? already essential to the economy of the United States and the world ? stays current by upgrading the existing telecommunications and technological network while also allowing room for growth in that area.

Jan 1, 2007

"INTRODUCTION The characterization of groundwater hydrogeology is a common component in feasibility studies, geotechnical investigations and regulatory permitting for mining operations. The lithology at a location of interest may include several discrete water-bearing units; and the means of isolating each for testing can be accomplished through the use of inflatable packers. Consideration for testing during drilling program planning and communication between all stakeholders is essential to ensure that the Mine, Drilling Contractor and Hydrogeological Testing Specialist (Specialist) are ready to perform packer testing when the call is made to mobilize. Often, the notice to mobilize can be delayed and then occur with little warning due to the issues that can occur during drilling of very deep boreholes, as well as other factors. Hydrogeological investigation reports and journal articles generally discuss testing methods and results, with limited information available describing the planning and coordination of the field testing program, as evidenced by the lack of references cited below. The source of inspiration for the subject matter of this paper is grounded in the author’s past shortsightedness; with the hope that others not share similar misfortunes but experience success through thorough preparation for their future hydrogeological testing programs. The sections below focus on the planning stages of a field investigation using inflatable packers, including considerations for site specific conditions, designation of stakeholder responsibilities, and communication of testing expectations. Following these sections is a presentation of two examples of successful field programs and lessons learned in addressing problems encountered along the way. PRELIMINARY PROGRAM PLANNING & CONSIDERATIONS From the onset of planning for drilling programs, the Specialist should be in communication with the Mine to review plans and identify fatal flaws which could impede collection of hydrogeological data. Preliminary scope decisions can significantly affect the budget and duration of hydrogeological field programs and may dictate the means by which the field data is collected. The issues that need to be considered include the following factors. Testing Objectives The setup of the packer tool is dependent on the testing objectives. Is the goal to estimate bulk aquifer hydraulic conductivity or to identify discrete discontinuity hydraulic characteristics? Are groundwater samples needed? The answers to these questions affect selection of test interval length and what instrumentation might need to piggyback on the packer tool. Identifying the testing goals initially will provide adequate time to prepare packer equipment for mobilization. Borehole Size While inflatable packers come in many shapes and sizes, some sizes are more readily available and easier to procure on short notice. Packers for NQ and HQ size boreholes have been historically easy to procure and are commonly used in exploration drilling. Packer equipment is available for smaller holes, but it becomes more difficult to fit instrumentation down-hole as the borehole size decreases. This is particularly a consideration if collection of groundwater samples is required. In addition, risks of losing the hole or equipment downhole are greater for smaller boreholes. Larger boreholes require larger packers and clearly require more effort and heavier capacity machinery to manually manipulate due to the increased size."

Jan 1, 2017

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 Neil White

South Africa (SA), a country in which all three commercially important asbestos minerals have been mined and milled, has retained proven cases of mesothelioma linked with environmental exposure to asbestos. This study illustrates the importance of fiber type in the occurrence of environmental mesothelioma. Four studies have reviewed the source of occupational or environmental asbestos exposure in 504 histologically proven cases of mesothelioma in South Africa. One hundred and eighteen cases (23%) were thought to be related to environmental exposure to asbestos. In the vast majority of these cases, exposure was linked to crocidolite mining activities in the Northern Cape Province. Two cases were thought to have occurred in relation to amosite and Transvaal crocidolite exposure in the Limpopo Province. In the balance of cases there was some uncertainty. No cases were reported with exposure to South African chrysotile. Consequently, in the vast majority of cases of mesothelioma, environmental exposure to asbestos occurred in the Northern Cape Province, in proximity to mines, mills and dumps where crocidolite was processed. Crocidolite appears to be far more mesotheliomagenic than amosite, and chrysotile has not been implicated in the disease. This is true for both occupationally and environmentally exposed individuals. ©2007 Elsevier Inc. All rights reserved. Keywords: Crocidolite; Mesothelioma; Chrysotile; Amosite; South Africa

Jan 1, 2007

By Thomas Gregor, Brian Garrod

As the popularity of precast concrete segmental linings for tunnels is growing in North America, some problems related to grouting of, and near, these linings are starting to appear. The installation of a segmental lining behind a TBM requires that the annular space around the lining be quickly filled with grout to prevent collapse of the ground. In practice, the filling of the annulus is frequently delayed and takes place a distance behind the machine typically via grout ports centrally located in the segments. If partial collapse of the annulus has occurred, it may become necessary to use higher grouting pressures in an attempt to distribute the grout. There have been several occasions where these increased pressures have caused damage to the tunnel linings. Similarly, compaction grouting adjacent to a tunnel lining can cause damage. This paper quantifies the effects of such grouting on a typical precast lining.

Jan 1, 2005

By C. Dirscherl

"Declining ore grade, leading to increased material transport and plant throughput requirements, is one of the major challenges in the current mining environment. This is accompanied by rising energy and labor costs, decreasing plant productivity and the requirement for highest plant availability. Siemens’ answer is the latest gearless drive technology for grinding and conveying. Gearless drive solutions are surpassing the mechanical limits of conventional drive systems serving to utilize the principle of economies of scale. By elimination of various components of the drive train the maintenance activities and spare parts inventories are reduced. The advantages are culminating in the incomparable availability of the Siemens’ gearless drive technology of 99.46 to 99.71% - as confirmed by real operational data from the Antapaccay mine in Peru. It was the first plant worldwide to use gearless drives for both applications. KEYWORDS: Gearless Mill Drives, Gearless Conveyor Drives, Availability, SAG Mill, Ball Mill, Overland Conveyor, Antapaccay INTRODUCTION – THE GEARLESS PRINCIPLE The principle idea behind a gearless drive system is to reduce the number of components and diversity of parts. Especially those components that are at the edge of current manufacturing or power limits are eliminated. The used equipment provides the possibility to scale up and increase the power transmitted to the driven machine. This finally results in a possible increase of throughput respectively transported or processed material. In order to apply this principle of simplification we will take a look at the components of a conventional drive system consisting of: - Driven equipment (mill, conveyor, slurry pump…) - Components altering the rated speed (gearboxes, girth gear / pinion) - The electric motor - Starting devices for the motor (VSD, CCV, LRS, clutch…), which are necessary because a direct across-the-line start of high power motors with load would result in a significant drop in the line supply voltage - Alternatively a variable speed drive (VSD) or cycloconverter (CCV) to utilize the possibility of speed variation during operation - The electrical supply system (cables, switchgear, transformers, protection equipment) Intermediate gearboxes are not required when a motor is used with a rated speed that directly matches the speed requirement of the driven equipment. Furthermore the VSD can be used to smoothly start the motor and to vary speed during operation, which means that it satisfies both requirements."

Jan 1, 2015

By R. P. Sloan, A. S. Whitford

In November 1999, CCI's Empire Iron Mining Partnership and MinnovEX Technologies Inc. developed an expert system for advanced control of their Empire IV Grinding Section. Empire IV is comprised of three autogenous Primary Mills and six autogenous Pebble Mills, with a single Pebble Crusher and high pressure Roll Press. The challenges of controlling and optimizing three distinct grinding lines that are inter-woven by a pebble crushing circuit were met with innovative and unique solutions. This paper will detail the approach employed at Empire and will focus on the aspects that make this application unique.

Jan 1, 2001

By W. McMahon

Following the Sago Mine accident, the Mine Safety and Health Administration (MSHA) asked the U.S. Army Engineer Research and Development Center to study several possible methane explosion scenarios in the Sago coal mine. The study used a 1-ft resolution map of the mine to produce a 3-dimensional (3-D) model of a portion of the mine, including the sealed area where the explosion occurred. An advanced 3-D computational fluid dynamics (CFD) code was used to calculate the explosion pressures within the sealed area, on the mine seals, and in nearby regions of the mine. Based on the best available information on methane concentrations and assumptions on homogeneity and on layering and mix composition, three separate initial conditions of methane-air concentrations and location were studied. This paper discusses the CFD modeling technique, the results of the calculations, the challenges of conducting this type of modeling, and the advantages and limitations of CFD modeling of accident investigations of mine explosions.

Jan 1, 2009

By Helmut Hass, Michael S. Shultz

For many tunneling, deep shaft and deep excavation projects ground freezing is one of the best if not the only technique available to create a watertight and load bearing temporary support system in soft ground conditions. When appropriate attention is given to the details of the ground freezing system design, ground freezing is a very safe method and is economically viable with competing techniques and combinations of techniques. Recent innovative uses of the technique in Europe are highlighted in this paper and compared with current uses in North America.

Jan 1, 2005

By Setareh Afrouz, Emily Sarver, Cigdem Keles

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

Feb 24, 2022

By M. Ge

Signal processing is a major challenge for In-Seam Seismic (ISS) technique. Fourier Transform is an important tool for signal processing such as frequency analysis. However, for ISS signal, localized information, especially time-frequency localization is even more important. Wavelet Transform (WT) provides another approach to study the signal as a function of frequency and time. The objective of this paper is to demonstrate the application and advantages of WT to seismic signal analysis. Both transmission and reflection signals from coal mine void detection experiments are analyzed. The results illustrate that WT appears to be a powerful and convenient method for the in-seam seismic signal processing.

Jan 1, 2007

By M. Pérez-Tello

A mathematical model to represent the expansion and fragmentation of copper matte particles oxidized under flash converting conditions is presented. The model assumes that the particles are initially nonporous, have a constant mass prior to fragmentation and travel at a constant velocity throughout the reaction chamber. The model requires the specification of the following five parameters: the particle expansion rate, a fragmentation diameter factor, a fragmentation size distribution parameter and the fractions of the finest and the coarsest particles in the feed that undergo fragmentation. The model predictions show good agreement with the experimental data collected in a laboratory furnace over a wide range of experimental conditions. The evolution of the size distribution of the particles along the reactor length was computed, and the model parameters were correlated with the experimental operating variables. Model predictions indicate that particle residence time is an important factor in the generation of dust. The presence of two maxima in the particle density function may be attributed to turbulent conditions prevailing in the furnace, which cause particles to follow different trajectories within the furnace even if they are injected at the same location.

Jan 1, 2008

By W. Szymanski

The United States contains one of the world's largest reserves of uranium. Domestic production and exploration activities, however, have declined since the early 1980s due to weaker-than-expected growth in nuclear power demand and to foreign competition. The main result has been that more costly and less productive conventional mines and mills have closed. Meanwhile, industry productivity as measured by uranium output per employee has increased threefold since 1980. At the end of 1992, only six plants, all nonconventional, were operating in the United States. Due to cost considerations and increased environmental awareness, any additions to existing capacity are expected to be met through nonconventional in situ leach plants.

Jan 1, 1994