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By J. F. Cornelsen

Wheel loaders are currently being used in many mining applications for a variety of reasons. While they sometimes provide the lowest loading cost, a primary advantage of the wheel loader versus other loading systems is the increased versatility and mobility inherent in a wheeled vehicle. The advent of large wheel loaders with much greater digging capability enhanced wheel loader usage in severe loading applications. To match these severe conditions, machines offered today were designed to work in these rocky conditions. Soon after the introduction of large wheel loaders into rocky conditions, however, it became apparent to many users that tire costs could at times account for up to 50% of total hourly operating costs on large wheel loaders. In some applications, tire costs alone pushed wheel loader economics beyond the economic feasibility for these jobs, prohibiting their use. In an effort to combat high tire costs, several attempts have been made to put fast moving steel around the tires to provide a strong interface between vehicle and ground. Some earlier attempts involved wrapping tracks around tires. Mechanical difficulties with these systems limited their customer acceptance. Subsequently, the development of protective tire chains came into favor. While tire chains offered added protection to the tires, the cost and maintenance of the chains remains a problem in 1972, the Dystred arrangement was announced for usage on a 6 cu yd wheel loader from Caterpillar Tractor Co. (See Figure 1). The Dystred offered the advantages of greatly increased tread life over conventional tires, as well as resistance to tread puncture in most situations. The arrangement basically employed a track system similar to that used on track type loaders. Pin and bushing wear often caused high hourly operating costs and excessive machine downtime. In addition, the connection of shoes through the use of links, pins, and bushings forced a limitation on too speed of the vehicle.

Jan 1, 1976

By Oscar M. Wicken

Iran was a lodestone for the attention of industrial countries and companies wanting to share in its industrial development during the last two decades and particularly after 1972. Prior to 1972, most industrial projects in the private sector were on a relatively small scale and could be carried out in reasonably orderly fashion in spite of limitations of a primitive infrastructure and meager indigenous supply of managerial and technical skills. People with these skills could be found but not in abundance, and many of them were total¬ly engaged in various government ministries and projects. Thus it was that nearly all private sector industries, even long-established ones, required one or more foreigners to give guidance. A barite mine and processing facility was brought on line by Dresser Industries in 1960 without serious operational problems. A few expatriate experts were able to select and train a stable group of staff and production people and establish sound management principles for continued growth. The huge and increasing oil revenues after 1973 gave superficial credence to ideas of the Iranian government that the country could easily finance the jump into the industrial 20th century. All necessary skills and equipment not available in Iran would be imported, and intensive training programs would prepare Iranians for operating the new facilities. Large projects for steel production, copper production, oil refining, petrochemical production, cement production, and others were started or expanded. These are basic industries that consume substantial quantities of refractories. Studies made in 1972 indicated that the existing industries plus expanded and new projects scheduled to come into production would lead to a market sufficiently large to justify a refractory producing plant. Concurrent studies of raw material sources showed that clay, the largest tonnage item, would be locally available; the other raw materials would be imported. Iran Refractories Company (IREFCO) was founded in 1973 and started production in 1976.

Jan 1, 1981

By Philip Weaver

The MIDAS project is funded by the European Commission (DG Research) and began on the 1st November 2013. The project will investigate the environmental impact of deep-sea mineral and energy extraction: specifically, polymetallic sulphides, manganese nodules, cobalt-rich ferromanganese crusts and the potential mining of rare earth elements. As deep-sea mining becomes ever closer, and the International Seabed Authority begins to develop its regulatory framework for exploitation of deep-sea minerals, MIDAS is well timed to provide fundamental scientific information. The MIDAS partnership represents a unique combination of scientists, industry, social scientists, legal experts, nongovernmental organisations and small and medium enterprises. MIDAS is carrying out research into the nature and scales of the potential impacts of mining including 1) physical disturbance of the seabed by mining, the creation of mine tailings; 2) the potential effects of particle-laden plumes in the water column, and 3) the possible toxic chemicals that might be released by the mining process. Key biological unknowns, such as connectivity between populations, impacts of the loss of biological diversity on ecosystem functioning, and how quickly the ecosystems will recover will all be addressed. The plan is to use this information to aid development of recommendations for best practice in the mining industry. A key component is the involvement of industry within the project and through stakeholder engagements to find feasible solutions. The project will work closely with European and international regulatory organisations to take these recommendations forward into legislation. A major element of MIDAS will be to develop methods and technologies for 1) preparing baseline assessments of biodiversity, and 2) monitoring activities remotely in the deep sea during and after exploitation, including ecosystem recovery. To carry out this work MIDAS is conducting a number of research cruises to examine the above issues at potential sites for exploitation of SMS and nodule deposits. This talk will present some of the recent findings of the project.

Sep 1, 2014

By Ken Deter

My recent experience has been with wet tropical environments, which address a different set of concerns than Nevada, for example. Spraying rather than drips are required in most cases just to assist the water balance requirement, and my comments address those situations. Most tropical operations are faced with both extremely wet and very dry seasons, with some having multiple cycles during the year. A heap leach operation must address the rate of solution building up within the ponds and how long the volume must last until the next rainy season. It may be easier to construct sufficient pond volume to permit yearlong operation than by discharging excess solution now, and searching for water later. Pond capacity requirements can help with the following: Consider using the solution that could be locked up in the pads during leaching to assist water balance problems. Spray excess solution continuously onto spent ore that would not be normally be sprayed again to "soak up" the excess solution, and stop spraying when the water balance is low, allowing the solution in the spent ore to return back into the system-with or without cyanide added. In a multiple lift system, if intermediate HDPE liners are planned for solution grade control, have drips placed before the HPDE liner is in place. The drips can distribute excess precipitation throughout the lower lifts to control the water balance, while the most current lifts are being leached and sent directly for the preg pond. With only 2 million tonnes (2.2 million tons) of spent ore involved, up to 200,000 cubic meters (53 million gallons) of solution could be moved into or out of the water balance system, if proper methods are designed and installed. That is equivalent to one meter (40 inches) precipitation falling on a 200,000 square meter (2.2 million square feet) pad area. You may even get a little bit more gold recovered as the solution drains from the earlier pads, as well.

Jan 1, 1999

By Richard M. Crowell, John W. Shield, Todd J. Harvey

Facing lower gold prices, gold mine operators throughout the world are seeking ways to reduce costs for treating refractory sulfide ores. Many gold mines, currently producing oxide ores, have underlying refractory sulfide deposits and the operators could extend the mine life by processing these sulfides. Fortunately, oxidation technologies for refractory ores need not be complex nor costly. GeoBiotics, Inc. has developed heap biooxidation technologies (GEOCOAT™) for treatment of refractory gold ores and concentrates. GEOCOATTM uses simple low cost unit operations common to heap leaching of gold and copper ores. The cost effectiveness and flexibility of GEOCOAT™ heap biooxidation allows mining companies to expand operations to include refract01y ore. In addition, GEOCOAT™ can be utilized to supplement or replace existing oxidation processes such as roasting, autoclaving, or agitated tank biooxidation, and to treat a lower resource grade than is currently economic. The GEOCOAT™ technology involves coating sulfide concentrates onto sized support rocks and biooxidizing the sulfides in a heap configuration. After biooxidation the concentrate is stripped from the support rock, neutralized and leached in conventional cyanidation facilities. Ashanti Goldfields Company Ltd. (AGC) produces over 885,000 ounces of gold per year from oxide and refractory ores at its Obuasi operations in Ghana. Refractory flotation concentrates are treated in roasters and in the world's largest stirred tank biooxidation facility. In August 1998, AGC and GeoBiotics jointly constructed and operated a field demonstration heap of the GEOCOATTM process at the Obuasi operations. The heap contained I 082 tonnes of support rock and 125 tonnes of concentrate. The heap was approximately 19 meters square at the base and 3.8 meters high, and ran for 88 days after which the concentrate was reclaimed. Average gold recovery after biooxidation was 91.5% with a NaCN consumption of 8.6 kg/t. Baseline gold recovery by direct cyanidation of the concentrate was 53.8%.

Jan 1, 1999

By Rebecca A. Miller, Terry M. Hertel

In-pit identification of neutral waste rock at the Zortman and Landusky minesites in Montana, by visual and chemical analy­ses, will assist in proper segregation and placement of rock so that soil and water resources can be protected. The use of too few or very general segregation criteria to identify neutral waste rock can result in ineffective waste rock segregation. Conversely, the use of overly restrictive criteria can result in the unnecessary loss of valuable reclamation material that would otherwise have to be mined elsewhere and hauled to the site. Recognition of nonre­active materials can be accomplished on a site specific basis with the use of visual observation and simple chemical analyses. The choice of chemical parameters used to analyze rock samples is constrained by the length of time needed to conduct the test. These analyses must require no more than 24 hours to complete so mining can proceed without delay. Limits set for the chosen parameters must be reasonable and defensible. To achieve these objectives over one thousand samples were collected at the Zortman and Landusky minesites and clas­sified by rock type, total sulfur content, paste pH, and net neu­tralizing potential (NNP). In addition, over 22 humidity cell kinetic tests were conducted to help corroborate static results for waste rock. Another 8 humidity cells were configured in series to test waste rock blending and waste rock/limestone capping alternatives as mitigation for acid rock drainage. Leachates were analyzed for pH, conductivity, alkalinity, acidity, sulfate, Al, Cd, Cu, Fe, Mn, Zn, Mg, and Cr in some cases. Petrographic analysis, as well as total sulfur content, paste pH, and static and kinetic test results identified three geochem­ically different waste rock groups: 1) Archean amphibolite gneiss and Paleozoic carbonates and shales, 2) Tertiary syenite porphyry, and 3) other less abundant Tertiary igneous and Archean metamorphic rocks.

Jan 1, 1996

By J. E. Stephens

US Borax began exploration in southeast Alaska in the summer of 1971 with a staff of two, Barry Watson and Jackie Stephens, based in Spokane, WA. After several years of prospect examinations in the islands west of Ketchikan, AK, and with the able assistance of prospector-pilot Kenny Eichner, Jackie Stephens proposed and organized a boat-based, helicopter-supported, stream sediment sampling program to explore the western contact of the Coast Range intrusive complex on the mainland. The rationale for this included: the extension of known mineral trends from Canada into southeastern Alaska along favorable geologic zones; the western contact area of the Coast Range intrusives with metasediments and metavolcanics was a favorable target for metals exploration as shown by numerous small prospects. Knowledge gained from mineral exploration of the island areas indicated that they were well mineralized, but already well explored, and that the known mineral potential was probably present in subeconomic quantities (Brooks, et al.). Publications of the US Bureau of Mines and other scientific agencies were gathered and every prospect within the southem southeastern Alaska area was plotted. This in itself lent a tremendous amount of knowledge to the total exploration program. US Borax's McLean Arm copper property on Prince of Wales Island was drilled and dropped while this compilation of data was proceeding. We found that many companies had followed one another around the island areas, but little or no exploration had been done on the west side of the Coast Range, and that many explorationists flatly stated that the west side of the Coast Range was barren of mineralization. In summary, although some of the shoreline and near shoreline areas of the mainland had been explored, no organized boat-helicopter exploration program had been done along the favorable western zone of the Coast Range Intrusive complex. We decided to use a boat as a floating hotel for the crews that were to be helicoptered into the back country from tidewater for our initial stream-sediment sampling program.

Jan 1, 1991

By G. Johnston, P. K. Chatterjee, S. Holguin

M. Gershon The article is an excellent one, providing a basis for the conduct of the major tasks in underground mine planning and scheduling. I object to only one word. Since that word is featured in the title, it is a strong objection. The word used erroneously is optimization. There is no optimization performed in the article. By definition, an optimization is an approach that yields the best of all possible solutions. We can limit this definition to its narrowest sense, the optimization techniques of operations research such as linear programming, or broaden it to include less sophisticated search procedures that find the best mine plan or schedule. No such claim is made in the article. No optimization of any kind is performed. The major tool used is a simulation, which, in truth, is probably more appropriate for this problem than any optimization. But simulation does not optimize. It only allows for quick evaluation of many options, leading to the selection of the best plan "of those tried," not "of all possible plans." This article, of course, is not the first mining paper to make this error. It seems that the word optimization is used more to impress people than to refer to any act of optimizing. It is used in a way that implies "try to optimize"or "come close to optimize," but not to really do it. It is usually appropriate to quietly ignore this error. But when Dr. Chatterjee, who has done so much good work in true optimization projects and whose work I have come to admire, makes such an error, it is time to publicly dispute it. Having discussed this very point with him in the past, I am sure that he will agree. If he can support this position in his response, perhaps people will start to listen and we can reduce the number of false claims of optimization. This should be easy for him in this case since the approach he used, simulation, is the more appropriate one anyway.

Jan 8, 1988

By M. G. Ayat, B. C. Scott

H. P. Ferri I refer to the article "Degradation Process in Coal Slurry Pipelines" by M.G. Ayat and B.C. Scott in the September 1988 issue of Mining Engineering. I would like to congratulate Dr. Ayat and his colleague on a very interesting and valuable piece of work. This article is an excellent one, describing a real phenomenon that has been ignored for so long. I do, however, have an objection. The article fails to address the degradation process when coal is processed or transported in other ways than slurry form, particularly those employed in this work. Could, for example, screening (wet or dry) have contributed to the extent of degradation? Perhaps scanning electron micrographs of the samples examined and after screening would have helped to clarify this. I would like to point out that degradation is also observed in pneumatic conveying systems, mechanical conveying, and other means of transportations employed by the mineral industry. Reply by M. G. Ayat We gratefully acknowledge Dr. Fern's comments on the subject paper. As he so rightly points out, the degradation process is a real problem, not only in coal slurry pipelines, but also in many handling and processing equipment employed by the coal and mineral industry. Scanning Electron Microscopic examination of samples may offer very little information about the extent of degradation for several reasons. One is that preparing a representative sample that has undergone degradation will be extremely difficult if not impossible. This problem is exacerbated by the fact that SEM requires only very small amounts of material for testing. Secondly, there is a sample preparation step involved in the SEM examination and, as such, it would be very difficult to associate the extent of degradation to either sample preparation or handling and processing operations. Finally, it is probably worth mentioning that degradation is a multi-faceted phenomenon involving many natural and man-made factors. The logical approach to this problem would, therefore, seem to be a "one-step-at-a-time" approach.

Jan 2, 1989

By N. E. Norman

A great deal of effort has been put forth in recent years to arrive at accurate projections of the demands for tunnels in this decade. In reviewing the statistics presented by various study groups, it appears that during the decade from 1960-69, there were some 1,335 miles of rock and soft ground construction tunnels excavated throughout the world. These statistics indicate 645 miles of rock tunnel and 689 miles of soft ground tunnel were excavated during the last decade. This is expected to increase to 3,000 miles in the 1970's according to projections made by various authorities in the field of construction tunneling. I point out the above statistics to emphasize two main points: (1) The demands for tunneling in this decade alone are staggering. (2) There is a fairly even distribution in the amount of rock tunneling and soft ground tunneling being excavated. Unfortunately, available statistics do not answer many important questions about tunneling which are of great importance to the contractor and to boring machine designers. For example, how many of the projects completed in the past decade involved both soft ground and rock tunneling? How many projects involved tunneling in conditions where both rock and soft ground were contacted at the same face. While the answers to these questions remain unanswered, I am sure most of you can think of numerous examples of projects where mixed face conditions are prevalent. Many of you are probably familiar with the Austin Crosstown Interceptor which was bid last month in Austin, Texas. Here is a project involving 57,000 feet of tunnel where limestones and clay shales are expected to be traversed. Another project, the Tonner Tunnels No. 1 and No. 2, near Los Angeles, involve some 22,000 feet of tunnel where mixed soil and rock conditions are expected. A large majority of the projected tunnels for this decade are to

Jan 1, 1997

By M. Gershon

The article is an excellent one, providing a basis for the conduct of the major tasks in underground mine planning and scheduling. I object to only one word. Since that word is featured in the title, it is a strong objection. The word used erroneously is optimization. There is no optimization performed in the article. By definition, an optimization is an approach that yields the best of all possible solutions. We can limit this definition to its narrowest sense, the optimization techniques of operations research such as linear programming, or broaden it to include less sophisticated search procedures that find the best mine plan or schedule. No such claim is made in the article. No optimization of any kind is performed. The major tool used is a simulation, which, in truth, is probably more appropriate for this problem than any optimization. But simulation does not optimize. It only allows for quick evaluation of many options, leading to the selection of the best plan "of those tried," not "of all possible plans." This article, of course, is not the first mining paper to make this error. It seems that the word optimization is used more to impress people than to refer to any act of optimizing. It is used in a way that implies "try to optimize" or "come close to optimize," but not to really do it. It is usually appropriate to quietly ignore this error. But when Dr. Chatterjee, who has done so much good work in true optimization projects and whose work I have come to admire, makes such an error, it is time to publicly dispute it. Having discussed this very point with him in the past, I am sure that he will agree. If he can support this position in his response, perhaps people will start to listen and we can reduce the number of false claims of optimization. This should be easy for him in this case since the approach he used, simulation, is the more appropriate one anyway.

Jan 1, 1987

By S. S. Churchill

Introduction Amidst the apparent chaos of the final push to complete a major construction project, a small group of specialists works with great intensity. Armed with yellow "in test" and green "turned over to operations" tags, these startup engineers follow detailed preoperational test procedures to confirm that a plant is ready to operate. They follow a test schedule designed to complete individual process system in the order they will be needed by operations. After extensive preliminary testing, the startup engineers begin the truly exciting part of their work - initial operations. The thrill of engaging the clutch for the first time on a 10,000 horsepower grinding mill makes all the long hours worthwhile. Preoperational testing and startup are of critical importance to the success of a project. No other aspect of a construction project allows such opportunities for success or failure, and no other aspect is so critically influenced by careful planning. At Bechtel, the tasks of preoperational testing and startup are among the responsibilities of the Mine and Plant Operations group. The Preoperational Testing Process Preoperational testing is the transition phase between constructon and startup on a new plant. It includes the preparation of detailed test schedules and procedures. The schedules are used to coordinate construction completion activities, so that systems are available for startup and operations in a rational sequence. The procedures form the basis for performing the testing and documenting its completion. Tests include instrument calibration, wire insulation tests, wire termination verification, mechanical alignments and inspections, and system cleaning and flushing. Where possible, the systems are then operated on water and their performance recorded. Normally, either the construction contractor or a team of specialists has the responsibility to perform preoperational testing. Witnesses to the testing may be owner operations and maintenance personnel, engineers from the design firm, or specialists assigned to the project who provide assistance and guidance to the contractor in addition to witnesing the work.

Jan 1, 1986

By B. M. Sadashiva Murthy

Increasing quantities of nutrients and pesticides in agricultural runoff in recent years has caused the more developed western nations to become concerned about diffuse agricultural pollution. Thus, the problem of diffuse pollution is of greater importance and concern for any integrated water quality management programme. The above mentioned sources and activities causing pollution to groundwater cannot be completely avoided. The best solution is to entail a firm understanding of the principles of solute transport through porous media. The complex factors that control the movement of contaminants in porous media and the resulting behavior of contaminant plume are usually intricate to assess because of interaction of many factors such as dispersion, advection, sorption, degradation, volatilization, etc. As accurate quantification of solute under field conditions is inherently difficult, the fate of nitrate and phosphate have been analyzed in laboratory column and channel studies. From the analysis of the breakthrough curves, the dispersion co-efficient for nitrates and phosphates through sandy soil was found to be 0.262 m2/d and 0.114 m2/d for column studies, 0.321 m2/d and 0.231 m2/d for channel studies respectively. The column studies revealed that the concentration of nitrates and phosphates increased steadily in the first few days (around 5 days) and then it increased rapidly after 8 to 10 days. However, it attained equilibrium after 20 days. Similarly, the channel studies revealed a steady increase in concentration of nitrates and phosphates in the first few days (1 to 2 days) and rapid increase up to 15 days and there after it attained equilibrium. In the study, one-dimensional analytical model has been developed which include the advection, dispersion, and a characteristic term called ?total elimination rate?. The comparative study of column and channel studies, and model output (in which the term total elimination rate ?K? is considered as zero) exhibited a variation of 30 to 50 % in leaching characteristics of pollutants (nitrates and phosphates).

Jan 1, 2008

By Jennifer B. Leinart

With the signing of the North American Free Trade Agreement (NAFTA), Canada, the United States and Mexico entered into an international experiment in economics amid a cloud of controversy that still lingers. Central to the controversy are the disparities in wages that exist among workers in the signing countries. Wage surveys completed by Western Mine Engineering show the degree of disparity that exists among the mining industries of those three countries. Labor costs constitute 30% to 50% of operating costs. So these wage differences are a matter of interest to the mining industry. It is unclear how much of a factor they are in determining where companies search for and develop new mines. That depends on where minable deposits are expected to be found. However, a deposit that may not be minable in the United States or Canada may be minable in Mexico because of lower labor costs. Some adjustments are anticipated for the Mexican mining industry if and when its wages begin to approach comparability with US and Canadian wages. Table 1 combines the results of four recent surveys. It lists benchmark wages for mining job titles common to all the countries. About 220 mines are covered by the combined surveys. Canadian miners' wages, converted to US dollars, are typically 75% to 95% of US wages, while Mexican miners' wages are less than 10% of those in the United States. Table 1 also shows that wage disparities are not confined to international borders. In fact, the difference in average wages between the US coal industry and the US metal and industrial mineral industries is greater than between the Canadian and the US mining industries overall. Table 2 shows that managerial, technical and administrative salaries show similar, but less pronounced differences among the three countries. Salaried personnel at Canadian mines earn 80% to 90% as much as their US counterparts, while those in Mexico earn 20% to 30% as much. Here again, average US coal salaries exceed average salaries for the US metal and industrial mineral industries.

Jan 1, 1998

By F. Allen Meek

The Upshur Complex of Island Creek Coal Corp. consists of approximatly 35.000 acres of both surface and deep mine researves located in Upshur County West Virginia. The principle seams on the researve are the Middle and Lower Kittanning. Other mining in the area during the late 1960's and early 1970's produced surface mines that exhibited severely acidic drainage characteristics both during the mining phase, and after reclamation was completed. The Buckhannon River, the principal drainage for the area, is a high quality, lightly buffered stream, that is periodically stocked with trout. Because past mining had caused post mining acidic discharges and the Buckhannon River was a valuable recreational resource, mining permits for the area were put on hold by regulatory authorities, until solutions to the acid mine drainage questions could be addressed. In 1978, the director of the West Virginia Department of Natural Resources appointed a Task Force consisting of Industry, Regulatory. and Academlc participants. This Task Force was charged with gathering information and evaluating field procedures used during mining to prevent acidic mine drainage. In 1979, the group published a document titled "Suggested Guidelines for Mining in Potentially Acid Producing Overburdens" which summarized material handling and mining procedures that could be employed to help prevent the occurrence of post mining acid mine drainage. In 1982, a Technical Advisory Committee was appointed consisting of well known researchers in the field of acid mine drainage prediction and prevention. The group was charged with the task of conducting research in the field of acid mine drainage prevention. Mining conducted at the Upshur Complex between 1979 and 1986 employed various acid mine drainage preventative techniques recommended in the suggested guidelines manual and techniques concurrently being researched by the Technical Advisory Committee. Costs for the various techniques were documented and the resulting post-mining water monitored. The results of these evaluations are used by Island Creek in the planning of future mining operations in potentially acid prodcuing environments

Jan 1, 1991

By William J. Maloney

OVERVIEW Blind drilled shafts are becoming increasingly popular, particularly in the Appalachian coalfields, as a secondary and sometimes primary means of ventilation. The reasons for the rebirth of the blind shaft are mainly due to it's economics, timeliness, safety characteristics and inherent independence from underground operations. Historically blind drilling has been used to a limited degree in hard rock and tunneling ventilation. With the recent advances in cutters, bit design, equipment and lining systems, particularly in the Appalachian coalfields, blind drilled shafts are once again the shaft construction technique of choice to the educated ventilation specialist. [ ] HISTORY OF BLIND DRILLING Blind drilling has it's roots in numerous places, including the Nevada Test site, the coalfields of Appalachia and Germany along with the uranium mines of Arizona. Early technology was developed using a variety of equipment mainly of oilfield origin with oilfield drillers entering the industry on a project basis only to "pull in their horns" and return to the oil patch. Shafts completed by oilfield equipment range from the shallow 5' and 6' lined shafts on the Nevada test site to two (2) 10' lined, 730' deep shafts in Alberta for heavy oil development. Several of these shafts were completed to extraordinary depths with the record being a 90" diameter, 6,150' deep shaft being completed in the Aleutian Islands of Alaska in 1969. EQUIPMENT Oilfield equipment is still being used on the Nevada test site but elsewhere specialized blind hole equipment has been developed to enhance the efficiency of particular applications. Where steel liners are required the A-leg derrick with a simple hoist and rotary system is used. The largest user of this type equipment in the world is the former USSR where blind drilling for mine ventilation is the norm. On applications where trip time and cutter changeout are a priority, top drive hydraulic rigs have been developed which are highly automated, efficient and mobile. These rigs are particularly well suited for tunneling applications where shafts are shallow and sites are usually tight.

Jan 1, 1993

By Bruce K. Cantrell, Stephen W. Stein, Kenneth L. Williams, David Hassel, Harvey Patashnick

In June 1992, the Mine Safety and Health Administration (MSHA) published the 'Report of the Coal Mine Respirable Dust Task Group; Review of the Program to Control Respirable Coal Mine Dust in the United States." As one of its recommendations, the report called for the accelerated development of two mine dust monitors: (1) a fixed-site monitor capable of providing continuous information on dust levels to the miner, mine operator, and to MSHA, if necessary, and (2) a personal sampling device capable of providing both a short-term personal exposure measurement as well as a full-shift measurement. In response to this recommendation, the National Institute for Occupational Safety and Health (NIOSH), Pittsburgh Research Center, initiated the development of a fixed-site machine-mounted continuous respirable dust monitor. The technology chosen for monitor development is the Rupprecht and Patashnick Co., Inc. tapered element oscillating microbalance. Laboratory and in- mine tests have indicated that, with modification, this sensor can meet the humidity and vibration requirements for underground coal mine use. NIOSH is continuing that effort by developing prototypes of a continuous dust monitor based on this technology. These prototypes are being evaluated in underground coal mines as they become available. This effort, conducted as a joint venture with MSHA, is nearing completion with every promise of success. The immediate benefit of this effort will be to researchers, regulatory personnel, and mine personnel, by permitting evaluation of specific mining practices to see which expose mine workers to excessive dust levels. Using this information, mine personnel can optimize mining procedures to reduce dust exposure. MSHA and the operators will also be able to use the dust concentration data to judge whether dust plan parameters are adequate to continuously maintaining environmental dust levels below the applicable standard. The second development recommended by the Dust Task Group was a person-wearable version of the continuous dust monitor. It will be a monitoring system designed to provide a measurement of worker exposure to respirable dust, both during and at the end of the shift.

Jan 1, 1997

By Timothy J. Orr, Jami M. Girard

A NIOSH study on occupational deaths between 1980 and 1989 indicated that in the United States, mining had the highest average annual fatality rate (3 1.9 per 100,000 workers) of any other major industry. Since "lack of training" was often cited as the primary cause of accidents, NIOSH has been investigating new methods for effective training. One such method is the use of low- cost, desktop computers to simulate a virtual mining environment. Computer-based training offers several advantages over conventional training because the computer programs provide a three- dimensional environment that allows the trainee to practice using evacuation routes, encounter mining hazards, and view mining operations without being exposed to any real danger. One major focus of the project is mine escapeway multiuser training using desktop virtual reality programs. Researchers have imported mine maps into the software for the purpose of practicing actual evacuation routes and procedures. Various scenarios for evacuation can be practiced in a three-dimensional computer simulation of the mine in a disaster situation, complete with smoke, fire, and other dangers. Depending on the trainee's job description (i.e., foreman, shift boss, beltman, etc.), certain tasks need to be performed in addition to navigating primary and/or secondary escape routes. Each scenario allows for individual or team-based training and provides a means to educate mine workers in hazard recognition and hazard avoidance. Using this program, mine workers can practice evacuating various mine layouts without the danger and expense associated with escapeway training in an actual underground mine. Each scenario can be changed to test the trainee's reaction in a variety of circumstances and run many times so the trainee can practice concepts. This training experience will help reinforce the knowledge acquired during more conventional classroom instruction, and the inherent flexibility of the program allows training materials to be tailored to meet the specific requirements of individual mines.

Jan 1, 2002

By Stefan Lorenz, Robert Galler

"The technical lifetime of underground structures does not only depend on the long-term behavior of individual support elements and material characteristics, but also on various boundary conditions, which influence the entire long-term system behavior of the structure. Thanks to the construction of second tunnel tubes and the corresponding cross passages sampling of support materials such as shotcrete, concrete of the inner lining and rock bolts including sheet membranes is possible. To evaluate the stresses and the supporting effects of the tunnel shells, flat-jack tests and different simulations were performed. With these simulations the percentage of the load bearing behavior of the shotcrete shell can be determined. From the results, conclusions for new design approaches for tunnel construction should be generated. New concepts, in which the outer lining is part of the permanent support elements can be considered. This approach would be applicable for conventional as well as mechanical tunneling. INTRODUCTION Tunnels are an indispensable part of modern transport infrastructure. As multi-generation structures their long-term preservation as well as their technical service life is of central importance. The current state of research in the field of durability of structural elements must be considered separately. In almost all areas a prediction of materials and structural components towards lifetime exists. System-wide investigations were rarely performed, so that there is no technical lifetime consideration of the outer lining in systems included. In this study the mechanical behavior of the interface connection in a double shell lining (DSL) tunnel was investigated in laboratory tests. Objective The target of this work is, at first, to create a large database with the lifetime of different structural elements and materials, which may be the basis of durability considerations of tunnels. Secondly, the goal of these investigations is to optimize tunnel designs and their dimensioning regarding to the technical lifetime. For that matter, it is necessary to analyze the selected approaches of the loss of strength and stiffness of the outer lining."

Jan 1, 2016

By S. G. Vick, K. E. Robinson, W. D. Webb

INTRODUCTION This paper discusses two uranium tailings waste disposal studies that reflect the United States Nuclear Regulatory Commission (NRC) regulatory actions and their changing requirements during the mid to late 1970's. Present guidelines require that all new uranium tailings impoundments be designed and constructed to eliminate, to the extent that it is reasonably achievable, exposures and risks to the public from the tailings. This includes positive measures for control of seepage losses from the impoundment and for control of radiological releases caused by wind and water erosion. Long-term stability of the reclaimed impoundment is also a very important requirement. That is, it is intended that the tailings impoundment, once it is reclaimed, will require little or no care or maintenance as long as the uranium tailings remain a hazard. Principally because of the long-term stability objective, the NRC has now identified subsurface burial of the tailings as the "prime option" for tailings disposal. The environmental implications of these proposed regulatory actions are obviously desirable. The economic implications the actions may have on a particular project are not always so obvious because they are so dependent on environmental suitability of site conditions. Selection of a site with favorable topographic, geologic and hydrologic conditions will usually result in the most economically and environmentally attractive alternative for tailings disposal. The first project discussed in this paper was initiated before the NRC guidelines had been developed to favour subsurface burial. At the beginning, seepage and radon emission control requirements were moderate. Constraints were imposed on the design by site topography, geology, and project capitalization considerations, factors which were dealt with according to straightforward engineering and design principles. More serious constraints were imposed by changing regulatory requirements. Unlike the more usual engineeringrelated constraints, regulatory requirements were upgraded during the design process, causing the design itself to undergo numerous modifications. The second project was initiated after the NRC proposed regulations had become better defined and below grade burial appeared to be the preferred

Jan 1, 1980