Search Documents

By Dennis Ofiara, Michael Lewis

An experimental 1.75 meter Shaft Boring Machine was designed and manufactured by The Robbins Company. The drill was used by contractor Drillcon Raise AB to drill test shafts at an SKB underground test facility. SKB is the Swedish authority responsible for safe management of nuclear waste materials. This “SBM1.8” Shaft Boring Machine was used to drill shallow test shafts ingranitic rock at SKB’s Aspo underground laboratory. The drill used a unique vacuum mucking system. The bored shafts were held to very strict tolerances for bore diameter, straightness, and verticality. This drill was launched and operated from a mobile launcher. Headroom and working space were limited. The SBM1.8 drill produced acceptable test holes. SKB will carry out several studies to determine the suitability of this geology, and of this technique, for safe nuclear disposal. In addition to future use at SKB, many applications are foreseen, particularly in the civil construction industry.

Jan 1, 2005

Editor?s note: Each year, Mining Engineering features an industrial minerals review. Several people put in a fair amount of time in developing the material for this issue, all the while doing their own jobs. Thank you to the industrial minerals annual review editor, to the Industrial Minerals and Aggregates Division technical committee chair and vice-chairs, and to the authors of the individual commodity profiles. Jim Norman, member SME, of Tetra Tech, is the industrial minerals annual review editor. Rajesh Raitani, member SME, of Cytec Industries Inc., is chair of the Industrial Minerals and Aggregates Division?s Technical Committee. The technical Committee vice chairs include: ? Vishal Gupta, member SME, of FlSmidth, Agricultural Materials. ? Candace Trimble, member SME, of Oil- Dri Corporation of America, and Bradley Van Gosen, of the U.S. Geological Survey, ceramics and refractory materials. ? Stanley Krukowski, member SME, of the Oklahoma Geological Survey, chemical raw materials. ? Russell Winn, member SME, of R.E. James Gravel Co., chemical raw materials. ? Justin Zdunczyk, member SME, of Plum Creek, construction materials. ? Jerry Gauntt, member SME, of Golder Associates, fillers and pigments. ? Michael Cheshire, member SME, of Los Alamos National Laboratory, sorbents, filters and process aids. ? Rajesh Raitani, member SME, of Cytec, Industries Inc., specialty minerals. Their help makes possible this June industrial minerals issue. On behalf of ME readers, the editors thank them.

Jul 1, 2013

By A. J. Martin, M. J. Peoples, D. J. Adams, A. Opara

"The weathering of coal mine waste rock releases iron, calcium, sulfate and associated trace elements like selenium (Se). Nitrogen species are also found in association with coal-mining drainages mainly due to the leaching of residual blasting compounds. Elevated concentrations of Se are a ubiquitous occurrence in coal-mining environments in British Columbia. A major concern with waterborne Se in British Columbia is the potential for its bioaccumulation in aquatic food chains.Treatment to remove Se from coal-mining waste waters has proven to be challenging for conventional water-treatment technologies. Compounding this challenge, many streams are characterized by high flows and low selenium concentrations. Conventional membrane and ion exchange treatments produce concentrated brine streams that are difficult to treat or require disposal. Conventional biotreatment systems use excess nutrients to provide the required electrons to compensate for inefficient and variable electron availability, as well as to adjust reactor chemistry.This paper's electro-biochemical reactor (EBR) technology provides a controllable and consistent supply of useable electrons to the microbes directly at a low voltage potential (1-3 V) and low current. In this manner, the EBR technology overcomes the shortcomings found in conventional systems, as it reduces the required nutrient addition and provides a more controllable, efficient, economical and robust biotreatment system. Additionally, the EBR process does not produce excess solids or biomass; therefore, solids management post-treatment is not required.Laboratory EBR bench-scale and on-site pilot-scale systems were used to treat five British Columbia coal-mine waste waters; influent Se concentrations ranged from 35 µg/L to 531 µg/L. Se treatment targets for the tested waters ranged from 5 to 10 µg/L. Mean Se concentrations in EBR effluents ranged from 0.5 µg/L to 1.4 µg/L, while reducing sulfate concentrations. The test data demonstrate that the EBR technology is an effective Se removal option for British Columbia’s coal-mining waste waters.IntroductionSelenium in Mining. Selenium (Se) is a naturally occurring trace element, which is an essential nutrient in small amounts (Thompson and Robinson, 1980; Brown and Arthur, 2001). However, it is also toxic to aquatic life, birds, and humans at very low concentrations. A major concern with waterborne Se is the potential for its bioaccumulation in aquatic food chains, resulting in acute and/or chronic toxicity to fish, water birds and amphibians (Besser et al., 1996; Conley et al., 2009)."

Jan 1, 2015

By R. H. Mullennex

Application of depositional analysis concepts is becoming an ever-increasingly more important and more useable tool in exploration and development of coals in the Appalachian basin. Over the past decade, a rather large number of studies, papers, and publications have addressed various aspects of depositional environments of coals and, to some extent, applications to development. As would be expected as regards a subject so complex as Pennsylvanian sedimentation in the Appalachian basin, certain academic studies have produced conclusions at variance in some aspects to those of other studies. Overall, however, there has been a building- block progression and general refinement with time of understanding of the depositional settings and other factors controlling Appalachian coal distribution, quality, and other minability parameters. Most attempts to explain coal seam characteristics have revolved around a basic deltaic model. Some have attributed certain seam attributes to upper delta plain deposition, other attributes to transitional-lower delta plain settings, and yet others to lower delta plain environments, and so on. While these approaches have provided valuable insight into some general coal characteristics, they are somewhat incomplete and are, in a sense, too broad for specific mine-scale applications. Further, it is apparent that in order for widespread peat accumulation to occur, there must be a drastic decrease in the energy of the depositional system and amount of sediment being brought in, compared to the active deltaic and coastal processes responsible for deposition of the large volume of clastic sediments that dominate the Pennsylvanian system of the Appalachians. Consideration of this fact implies that peats (coals) may not necessarily reflect depositional settings that are directly coincident with those associated with adjacent rocks. Cecil and Englund (1985) address this point, and quite correctly state that "the primary controls on major stages of peat formation are allocyclic processes involving paleoclimate, eustatic changes in sea level, and tectonics." While this statement is inarguable, it does not negate the importance and usefulness of depositional analysis in predicting reserve characteristics that may impact mining and marketability.

Jan 1, 1986

What is the preferred electrolytic cell design and why? Hall: Considerable research remains to be done on electrolytic cell design. Studies are presently being conducted to determine optimum voltage and amperage. Zadra cells, which were used in some of the first carbon plants, are efficient when properly installed. Gold and silver are deposited on large-capacity, cylindrical steel wool cathodes. At times high value sludge falls from the cathode to the bottom of the cell. Rectangular cells, which were developed at some smaller operations in Nevada, require less floor space and have some desirable features in that cathodes can be moved and sludge can be removed from cell bottoms without actually shutting down the circuit. In South Africa two types of cells using graphite and diaphragm configurations are being tested. Duncan: The rectangular cell has one problem it's easy for shortcircuiting to occur. If you don't have a good seal on the side of the tank and on the bottom, the solution is going to want to flow around the bottom and sides of the cathodes and you're going to get poor performance in the cell. That is the advantage the Zadra cell has over the rectangular cell. With good sealing, which is a must, you should be able to get a ratio of the value of the solution going in to the value of the solution coming out of 10 to 1. Ken, can you tell me what you're attaining on the Zadra? Hall: At the Homestake gold operation in Lead, the cathode in the No. 1 electrowinning cell is loaded to about 600 ounces when it is moved to the refinery. At this time the No. 2 cathode is moved to the No. 1 cell. The No. 3 cathode is moved to the No. 2 cell and a cathode with new steel wool is placed in the No. 3 cell. In rectangular cells this sometimes is not possible because the loading on the cathode in the last cell may be as high as that in the No. 1 cell. As Don has pointed out this can probably be prevented by good seal design between cathodes. Potter: At the risk of sounding as though I'm straddling the fence, I really believe that either the round cell, as developed by Jack Zadra, or the rectangular cell will do an acceptable job. The Zadra is a fine unit. Leaks are not unknown but there are not very many. However, the rectangular cell is very saving of floor space. Plastics have been greatly improved during the past year or two and there is a very efficient design for the rectangular cell. It would have six cathodes in it and contain about 25 ft of steel wool. The body of this rectangular cell would be reinforced fiberglass plastic but with an integral lining of a high temperature plastic. I think either cell is so efficient and reliable that I would almost be tempted to flip a coin depending on floor space requirements. Either cell can be used to pull a loaded cathode and to advance the lesser loaded cathodes. Don, what is the configuration of your cell? Duncan: The Pinson rectangular cell has dimensions 2 ft wide, 30 in deep, and 10 ft long-long enough to take a dozen cathodes and anodes. We are currently using six of each but are not up to full capacity as yet. It's a steel tank coated with rubber. We have copper bus bars, which brings to mind that the last cathode in the tank, in one instance, was loaded heavier than the first one. That was probably a function of poor contact between cathodes and the bus bar. You can have erosion of the bus bar and if you don't get current flowing into the anode and out of the cathode, the cells will not function properly. Kappes: Just a few comments on cell design. In an alcohol stripping circuit we are running in Beatty„ NV, we are using PVC pipes for all circuitry piping and a commercial polypropylene electrolytic cell. They seem to be working quite nicely. The cell itself has eight cathodes measuring 18 in2. At six gallons per minute flow into the cell, at an average gold content of about 500 ppm, we seem to get good loading on the first three to four cathodes and not much on the end cathodes. At 12 gallons a minute flow we seem to be seeing gold uniformly along all eight cathodes. We are running at quite a high amperage level, about 400 amps into that cell. Gene McClelland, US Bureau of Mines, Reno Research Center (from the floor): I was associated with a company where the packing density of their steel wool cathodes was much too high and created some short-circuiting problems in their electrowinning circuit. I would like to ask the panel if they can recommend a packing density for cathodes in pounds of steel wool per cubic foot. Hall: The weight of steel wool put on one of our cathodes is 10 lb and the dimensions of the cathode are such that density would be about 0.75 lb/ft3. Duncan: I made a rough calculation and I'm estimating about 2 lb/ft3. Potter: In checking over a number of electrowinning operations, I found apparently very satisfactory operation within the limits that have been mentioned. I have come to a figure of about 0.5-1.0 lb of medium grade steel wool per cubic foot packed as uniformly as possible, of course. One consideration in packing is the fact that there should be good contact between the steel wool and the conductor. Operators tend to compact the steel wool more than would be desirable just to try to maintain good contact.

Jan 10, 1981

By Michael E. Zellars

The distribution of phosphate in Pliocene-Miocene deposits of the Southeastern United States was controlled by the prevailing geologic setting. For each basin a unique set of conditions in terms of relationship of land mass to shelf, depositional environment and seawater composition, and movement controlled phosphate distribution. Concentration sufficient to recognize the deposits as a resource occurred in lagoons or shallow neritic zones, with clastics and carbonates diluting the section basinward. Each deposit within a basin displays similar metallurgy and lithology, notwithstanding post-depositional alteration.

Jan 1, 1978

By J. B. Platt

Many utility fuel choices 1990-95 defied expectations, with utility decisions and coal market developments ever more closely linked. The Central Appalachian coal boom never occurred; clean-enough coal was developed in the hard-hit Midwest; Colorado-Utah coal surged; Pittsburgh seam production strengthened; utilities embraced Powder River Basin coal; and emission allowance prices collapsed. Competition drove productivity gains, but the future is not a simple repeat. Phase 2 brings fewer viable compliance options. Mega-railroad pricing has become a key risk factor -- will this be countermanded by merging utilities and power market competition? Revenue losses from vintage contracts are problematic. Uncertainty also plagues natural gas, in spite of unanimity across major forecasts, since recent experience has been so heavily influenced by the gas bubble.

Feb 24, 1997

By G. T. Lineberry

Underground mine development begins with the positive investment decision to mine and ends with the inception of full-scale exploitation. It incorporates all activities, personnel, and equipment required for creation of underground access to a mineral deposit. Because of the depletion of near-surface mineral resources, the reduced mobility of large surface mining equipment, increasingly stringent environmental constraints, and the introduction of promising innovations to rock penetration and rock excavating equipment (e.g., continuous miners, rock borers), under-ground mining is projected to account for an increased share of worldwide mineral production in the foreseeable future. Without proper engineering during the mine development phase, failure of the underground mining project is axiomatic. A frustration attendant to coverage of the complex area of underground mine development lies not only with the need for treatment of the many disparate specialties within the area but even with the lack of systematization of these specialties in what is recognized as a vital precursor to successful mining. Section17 offers insights into (1) the basic principles of the planning and design process, including baseline assessment, reserve determination, premine planning, and subsystem design (Chapter17.1); (2) equipment selection and sizing, with emphasis on exca-

Jan 1, 2008

By Steve Kral

The domestic mining industry may be in the doldrums but there appears to be hope, at least from a regulatory standpoint. At least one US senator believes that the events of Sept. 11, 2001 made many citizens see the need for the country to become more self-reliant on its growing energy needs. Even before that tragic day, however, the Bush administration was making a strong push to open up more public land for energy and natural resource development.

Jan 1, 2002

By Dimitrios Litsas, Michael Kavvadas, Panagiotis Sitarenios

"The paper discusses the results of 3D finite element analyses to investigate the effect of face support pressure and soil permeability on face stability conditions in EPB tunnelling. Two main types of face behavior are identified: Undrained conditions ahead of the tunnel face, typically occurring in soils with permeability less than about k=5·10-7m/s, are shown to be favourable for face stability; analyses show that an applied face pressure comparable with the initial hydrostatic pore pressure is sufficient for adequate face stability, even for soils of relatively low strength. Drained or partially conditions, typically occurring in soils with permeability higher than about k=5·10-6m/s, show that face stability is strongly dependent on the horizontal effective stress of the muck in the excavation chamber; the presence of even a small effective stress in the muck is very beneficial for face stability conditions and can be a possible explanation of successful EPB tunnelling through relatively permeable soils. INTRODUCTION Face stability is probably the most important aspect in urban tunnelling. Usually, Earth Pressure Balance (EPB) machines are utilized, to ensure that a reasonable amount of face pressure is exerted on the advancing excavation face, reducing ground loss and preventing potential instability of the face core, thus controlling the amount of disturbance caused by tunnel excavation to surface structures. However, the ideal amount of face pressure depends on several factors (ground and groundwater conditions, tunnel size and depth, muck conditioning, etc.) which are difficult to include in analytical calculations. For many years, conventional empirical or analytical methods (e.g. Anagnostou & Kovari 1996) were the only available tools for quantifying face stability and selecting the required face pressure. In the last few years, however, numerical analyses have gained power over conventional methods, allowing more accurate designs and providing useful information about the anticipated ground deformations due to tunnelling. Numerical analyses have also been used in assessing safety against face instability using face extrusion (horizontal face displacement) calculations (e.g. Prountzopoulos 2012)."

Jan 1, 2016

P.T. Freeport Indonesia's latest expansion has increased total mill throughput to 125,000 dry metric tonnes per day. The most recent expansion included the installation of a Semi Autogenous Mill designed to treat more ore than any other single SAG mill currently operating in the world. Also included in the expansion were two large ball mills, rougher and cleaner flotation including conventional and column cells and a regrind circuit. All equipment is supported by a modem distributed control system. This paper describes the design considerations, construction, commissioning and start-up of the SAG concentrator and support facilities and includes an overview of the oreflow and milling facilities.

Jan 1, 1996

By Jean-Michel Rendu

That you are giving the Daniel C. Jackling award to me is a great personal honor. But more significantly, it is a recognition that geostatistics has come of age. And since I am considered by many as belonging to an older generation of geostatisticians, I thought that it would be fitting that I reflect on where geostatistics came from and where it might be going. First, though, let me propose a definition of geostatistics. Etymologically, paraphrasing Webster's definitions of "geo" and "statistics," it is "a branch of mathematics dealing with the collection, analysis, interpretation and presentation of masses of numerical data taken from the earth." This definition is most appropriate in the context of mining geostatistics. It includes both classical and spatial statistics. It emphasizes the earth aspect, or the analysis of geologic features. And it should remind the practitioner that geologic input is a critical part of all geostatistical applications. In the 1910s, statistical methods were already used to analyze geological data. However, the origin of geostatistics, as we know it today, is best set in the late 1940s, when H.S. Sichel recognized the lognormal distribution of sample values in the South African gold mines. In 1951, Daniel Krige observed that "it can be expected that the gold values in a whole mine will be subject to a larger relative variation than those in a portion of the mine." In other words, samples taken close to each other are more likely to have similar values than if taken farther apart. This observation is the foundation on which spatial statistics, which characterizes values defined in a multidimensional space, is built. However, the 1950s were marked by studies based on classical, as opposed to spatial, statistics. It was only in the 1960s that the need was recognized to model the similarity between sample values as a function of the distance between samples and that the semivariogram was defined. A theoretical framework was developed by Matheron that supplied an elegant mathematical explanation to the empirical observations made by Krige. Matheron coined the term "kriging" in recognition of Krige's pioneering work on the geostatistical evaluation of mineral deposits. As soon as this theoretical framework was developed, it was possible to bring geostatistics to the academic world. The "Centre de Geostatistiques" was founded in Fontainebleau. Numerous students were trained there, disciples eager not only to improve the theory and develop more sophisticated mathematical tools, but also to spread the new faith throughout the world. Expansion of geostatistics exploded in the 1970s, arguably the most fertile decade if it is judged by the frequency of theoretical breakthroughs, the number of original publica-

Jan 1, 1995

By Charles J. Kucera

Today's highly publicized issues of resource development and environmental protection are not new. But recently these issues have been played one against the other, and some would have us believe they are mutually exclusive. Why? Because modern man has realized that the shortest route to achieving economic progress is to subdue nature. He extracts mineral resources from the earth to provide the raw materials upon which other processes and services are based. But often in his search for economic progress he finds that other highly- held values (e.g., an unspoiled environment) have been violated. The natural response is a counter action - to attempt to protect nature. But this response is basically unsatisfactory because it is reactive.

Jan 1, 1979

By J. Kretschmann

Mining heritage can be of outstanding value for many regions around the world, because mining has been done for thousands of years for the benefit of mankind and its development. This paper presents an ongoing project creating a general guideline for the handling of mining heritage on the basis of experiences made in Germany. Interactions of stakeholders in the ?heritage network? as well as strategies for the technical proceeding will be described. An action plan for the sustainable handling of mining heritage has already been developed in part, which includes necessary measures. Best-practice recommendations will be derived. Keywords: m ining heritage / preservation / guidelines / action plan / Sustainability

Feb 27, 2013

By George L. Wilhelm

Timber support of mine openings continues to be an effective system for ground support, due to its avail¬ability, flexibility, and ease of installation. Timber support of mine openings as a primary method to support loose rock has been replaced to a large extent by rockbolting and by filling systems. How¬ever, the many designs of square-set timber and varia¬tions of crib and stull support that have been developed to suit many stope configurations have proven reliable over many years of application. Integrated in modern excavation and stoping methods, timber remains an im¬portant ground support material for today's mines. ADVANTAGES AND DISADVANTAGES OF TIMBER SYSTEMS Timber, when used as a part of the total support system, is recognized for its unique support properties. More than a cover to prevent minor falls of ground, timber systems have been carefully designed to provide adequate support with sufficient compressive qualities to achieve a safe working environment in extremely diffi¬cult ground conditions. In some cases, a timber support method is designed to yield while retaining its protec¬tive support qualities. Little or no initial investment in equipment or plant is required for incorporating timber into the mining support system. Low cost cutoff saws and portable chain saws are sufficient equipment for effective use of dimen¬sioned (sawed) or round (stull) timber support. Until recently, small sawmills of various complexity were com¬mon at mine surface plants. Sawmills at the mine sites have generally been replaced by timber vendors' mills. Suppliers have been able to use efficient cutting and lumber handling methods to reduce the cost of mine timbers. Most suppliers will package dimensioned mine timber into bundles that are suitable for handling down mine shafts and on level conveyances. The principal disadvantage of timber as a support method is higher material cost and labor cost associated with its labor-intensive installation. Furthermore, stand¬ing timber reserves of mine quality wood are in short supply in some areas, and heavy competition exists for alternative uses of the timber supplies. Vendors are reluctant to supply large cross section dimension tim¬bers relatively free of defects. Some mine operations require 4.8-m (16-ft) lengths of firm timber over 0.09 m2 (144 sq in.) in section and these are difficult to obtain in large quantities. APPLICATION OF TIMBER FOR MINE SUPPORTS Timber used in mine support has been cut from many species of trees. A firm hardwood with physical properties similar to western Douglas fir has been pre¬ferred in the US. Other harder and softer woods, how¬ever, have been used when readily available or where the specific strength or crushing quality of the wood is a desired specification of the support system design. Hard¬ wood, commonly oak, has been used where maximum crushing resistance is required. Mahogany and fir are widely used for shaft guide timber. Normally, timber is used with its core axis parallel to the long axis of the timber dimension. However, in some cases, it is placed normal to its core in a "butt" log position, so as to provide maximum resistance to abrasion of the ore passage adjacent to the cut end of the block. By selective placement of timber block¬ing, controlled resistance to ground closure can be achieved which will prevent early failure of primary sup¬port members of the timber structure. Timber is widely used in modern mining operations as a construction member for chute-lip support. These designs are tailored to each operation to conform to the dimensions of the haulage equipment being used. As a construction material, wood requires none of the spe¬cial equipment necessary for placement of concrete or steel support. Placement of these alternate support ma¬terials requires carefully dimensioned and engineered excavation for their installation. Wood can be easily sawed to fit on location. The successful use of timber in heavy ground de¬pends on the careful and accurate placement of block¬ing and bracing to achieve the controlled yielding re¬sistance needed to support the mine opening. Similarly, frequency, size, and placement of top and bottom block¬ing stulls in flat-bedded deposits are carefully determined to provide adequate support at the mining face. Con¬trolled caving through failure of the stulls may be required as the scope retreats from the earlier mined-out sections. The support program must achieve both of these dimensionless qualities by specification of stull frequency and size. The utility of the square set-system of ground sup¬port and timber support is described in Chap. 2, re¬printed from US Bureau of Mines Information Circular 6691. Four examples of effective use of timber for support of stoping and other mine openings are pre¬sented in other chapters in this section. The Gilman mine's use of Mitchell slice stoping described in Chap. 3 is an early modification of the square-set mining system. This application proved reli¬able for heavy ground and overcame some of the dis¬advantages of conventional square-set timber. Chap. 4 describes the Burgin mine's use of timber with other reinforcement material. This combination of materials achieved high strength and control with yielding com¬ponent members necessary for heavy, squeezing ground. Chap. 5 describes the Bunker Hill mine's use of square¬set timber in a new configuration that provides an effi¬cient and safe support for stoping using small load¬haul-dump (LHD) mobile equipment. Chap. 6 describes some considerations in placing the widely used stull in bedded ore deposits. Finally, in Chap. 7, cost calcula¬tions for

Jan 1, 1982

By Wern-ping Chen, Jean Habimana, Jinyuan Liu, Mirza M. Rabbaig, Robert Barbour

To mitigate and control the combined sewer overflows from 17 outfalls in the City of Detroit, three outfalls in Dearborn Heights and eight outfalls in Redford Township, the Detroit Water and Sewerage Department has completed the preliminary design of a storage tunnel in 2005. In 2006, a final design has revised the alignments and the inside diameter (ID) of the tunnel. The revised tunnel system includes an 11.28-km(7-miles) 9.14-m (30-ft) ID tunnel, a 24.4-m (80-ft) ID pump station, two work shafts about 15.2-m (50-ft) ID each, and 14 drop shafts with various IDs. This paper discusses the latest development of this tunnel system.

Jan 1, 2007

By Barry A. Hillman

The rapid evolution of computer and field sensor technology is now providing the ability to integrate mine and office operations. Digital maps and mine plans as well as CAD and GIS can be transferred to ruggedized field computers for development of real-time mine surveys and real-time GPS machine navigation and monitoring. Surveyors can insure that their surveys are accurate before returning to the office. Engineers and surveyors are also able to upload field computer-based surveys to mine planning software and directly to mine equipment including shovels, drills, and dozers providing the operator of the equipment with a real-time view of their work space. Production information can be transmitted through dispatch and/or centralized mine servers to update mine plans with mining progress and production data. Static mine models then become a dynamic element of operations, providing greater use of information that emphasizes the spatial aspects of the mine by providing real-time maps, productivity charts, and graphs. This information can be disseminated through various mine communication systems to provide operators and management with real-time feedback as well as daily and weekly reports. Integrated systems now being used in extensive trials are reporting productivity increases of 4 -7% or more thereby providing rapid payback to the mine.

Jan 1, 1998

By F. Maciosek, D. Denton, J. Johnson

Researchers from the Spokane Research Laboratory of the National Institute for Occupational Safety and Health and personnel from Coeur Silver Valley, Wallace, ID, conducted tests using rock strain strips and Split-Set rock bolts instrumented with strain gauges to monitor wall rock strain at the Galena Mine, Osburn, ID. The objective of the test was to identify whether strain on the rock bolts increased prior to a rock burst. Although results were inconclusive, researchers learned that the Split-Set rock bolts yielded in stick-slip fashion in the highly jointed walls of the stope. The bolts were also bent as stress was redistributed following blasting and subsequent movement along joints in the wall rocks.

Jan 1, 2004

By William Crowe Kellogg

By now the term AFMAG has been fairly well introduced to the mining industry. Several papers have been presented and published concerning AFMAG (references 1 and 2). However, the term AFMAG remains rather new to the industry, and the exact place which AFMAG occupies in the minerals exploration field is still somewhat uncertain in the minds of many who may have use for this new and interesting method of electromagnetic exploration for conductive minerals. It is the purpose of this paper to again review the basic theory of the AFMAG system, to describe and - illustrate the equipment and data presentation as used in aerial surveying, and to provide some idea of the cost and nature of airborne AFMAG surveys. This paper is primarily of a general descriptive nature and presents AFMAG theory in a schematic rather than mathematical form; emphasis is placed on the equipment, the present method of data presentation and survey operations, since it is believed that such, information will now generally best serve to inform the mining industry of the characteristics of the AFMAG system.

Jan 1, 1960

By Jeffrey A. Yonkey, Timothy J. Lutz, Jacob L. Carr, Christopher C. Jobes

"Since 1984, there have been 39 fatalities involving striking and pinning of the operator and other workers by the continuous mining machine (CMM). In January 2015, the U.S. Mine Safety and Health Administration (MSHA) finalized a regulation to require proximity detection systems on all continuous mining machines except full-face machines (MSHA, 2015). Proximity detection systems are designed to stop machine motion to protect miners from striking/pinning hazards. Several MSHAapproved proximity detection systems are commercially available.NIOSH researchers have been involved in the development and testing of proximity detection technology since creating the HASARD system (Schiffbauer, 2002) and have recently conducted research intended to develop more advanced proximity detection technology for CMMs (DuCarme et al. 2013; Jobes et al. 2012; Carr, DuCarme et al. 2013 and Carr, Li et al. 2013). In addition, NIOSH has also conducted research investigating how the signals of a proximity detection system propagate (Li, Carr et al. 2013 and Li, Jobes et al. 2012) and have developed a novel method for determining the location of a personal wearable device (PWD) relative to the magnetic field generators (Carr et al. 2010 and Jobes, et al. 2012).To evaluate the performance of proximity detection systems implemented in industry, NIOSH researchers conducted tests in 2013 on three systems installed on CMMs at three underground mines in Illinois and West Virginia. The results of these tests indicated that, while generally consistent performance was observed, there were opportunities for improving performance. These results were presented at the 2014 SME Annual Meeting (Carr, Lutz, et al. 2014). Since that time, second-generation systems have become available to the industry and are becoming more commonly used.Beginning in early 2014, NIOSH researchers conducted underground testing of these secondgeneration proximity detection systems installed on CMMs. Five tests were conducted on four installations of second-generation proximity detection systems, with one installation being tested twice. The tests were conducted at mines located in Illinois, Virginia and Kentucky with seam heights ranging from 137 cm (54 in.) to 213 cm (84 in.). These tests were conducted using the same test protocol used during first-generation testing, which is summarized in the following section."

Jan 1, 2014