Search Documents

By R. A. Hill

A brief explanation of the theoretical functioning of a regenerative system followed by its application to firstly, shuttlecars and then continuous miners and its effect on performance thereof with regard to handling, production and safety.

Jan 1, 1986

By G. Krogman, C. Walla, B. Wood

The Gebo Mining District (District) is located in the Bighorn Basin of Wyoming. Commercial underground coal mining began in 1906 with the arrival of the railroad in Thermopolis, which is located approximately 11 miles to the south. Mining in the District ceased by the early 1970’s. In Fall of 1999, Lidstone and Associates, Inc. (LA) and their subcontractors were retained by the Wyoming Abandoned Mine Land Division (WyAML) to perform an inventory of over 500 abandoned mine sites across Wyoming. During the summer of 2000 field inventory, a 30-foot deep headcut (Figure 1) and sink-hole were noted in the West Fork of Sand Draw (WFSD), immediately west of the Town of Gebo. The headcut and sink-hole were located at the culvert outfall associated with a stream crossing of a relatively well traveled county road. Upon further investigation, it appeared that underground mine workings had been exposed at this location. This resulted in a condition whereby water would be conveyed directly into the mine workings during a runoff event. The exposed mine workings as well as stream capture created a very hazardous condition. The WyAML implemented mitigation measures in the summer of 2000 by constructing a temporary stream crossing upstream of the existing failed crossing. To address this hazardous situation as well as a number of other hazards identified in the District during the field inventory, the WyAML retained PHC Reclamation, Inc. (PHC). PHC was directed to perform a field investigation and develop a Reclamation Plan to address all existing abandoned mine hazards in the District. Federal, state, and private parties own lands within the District. Hazards identified during the investigation included an underground mine fire, open adits, open shafts, subsidence, drainage problems, and coal slack. A Report of Investigation (ROI) was submitted to various regulatory agencies that documented the existing conditions and conceptual reclamation plans to remediate the hazardous conditions. After review of the ROI by the US Department of Interior - Bureau of Land Management (BLM) an on-site meeting was conducted. BLM Cultural Resource personnel declined to approve a District reclamation project until a historical overview of the entire District was prepared. Due to the hazardous situation associated with the WFSD stream crossing, Hot Springs County Road and Bridge Department convinced various state and federal regulatory agencies to allow reclamation of the stream crossing to occur. A decision was made to allow reclamation on privately owned lands within the WFSD drainage. This decision limited the amount of channel that could be subjected to reclamation upstream of the crossing to privately owned lands. PHC contracted LA to perform a geologic, geomorphic, hydrologic, and hydraulic investigation of the drainage to assist in the development of a WFSD reclamation plan. LA’s investigation consisted of four parts: Delineate the extent of mine workings in the area; Identify all drainage structures that required mitigation; Survey a series of channel cross-sections and a longitudinal profile of the impacted channel; and, Develop basin hydrology to assist in the design of a stable reclaimed stream channel.

Jan 1, 2006

By A. Davis, C. Webb, J. Sorensen

The abandoned Belle Eldridge Mine near Deadwood, South Dakota, is on land controlled by the U.S. Bureau of Land Management (BLM). The mine produced lead and zinc during the first half of the 1900s. Because of acidic drainage and elevated levels of metals in tailings and waste rock, the site was evaluated in 1998 and 1999. After evaluation, the mine was remediated during 1999-2001 by the BLM. Since remediation, values of pH in water samples have been nearly neutral and specific conductance values have been much lower than before remediation. The Grizzly Gulch forest fire of July, 2002, consumed much of the Belle Eldridge site and resulted in greater than normal erosion and sediment flushing during the months following the wildfire. Had the site not been remediated and the tailings emplaced within a capped repository, generation of acidity and off-site migration of heavy metals within sediments could have been severe at downstream locations.

Jan 1, 2007

By R. W. Carn, D. Vincent

Environmental Considerations With significant increases in bulk coal movements through terminals, operators are under constant social and political pressure to reduce or remove environmental pollution problems incidental to their operations. To meet these requirements, both equipment manufacturers and terminal designers are endeavoring to design equipment and systems with stringent environmental controls. The most challenging environmental problems facing coal terminal designers and developers are terminal siting restrictions, dust control, and noise abatement. Terminal Siting Finding a suitable site can be a difficult problem because of public concern over coal dust or the impact of a terminal on the surrounding community or natural habitat of the area. Often the only suitable flat land available for terminal development is on a tidal estuary or salt water marsh with great environmental value. In many cases a period of four to six years of full environmental and social assessment has been needed. A recent example of such difficulties is the expansion at Roberts Bank, British Columbia, where environmental impact assessment studies and their public review took almost six years from initial expansion applications until the time of approval. Dust Control Modern coal terminal dust control techniques usually consist of water sprays at strategic locations to suppress dust. The application points include rail car or barge dumper, main conveyor transfers, perimeter sprays around stockpiles, stacker/reclaimer, ship-loader transfers, and loading spout. The water sprays may include a chemical wetting agent or surfactant to reduce the water requirement and increase effectiveness. Recently there have been advances with development of effective micro foam agglomerating agents. In these systems, a micro foam with very small bubble sizes is sprayed into the coal stream. The foam fills the interstices between coal particles and wets the coal fines. These systems have proven to be very effective and usually one application before stockpiling and one upon reclaiming will markedly reduce the coal dusting. Stockpile perimeter sprays can be operated either manually or at the sophisticated terminal, actuated by a computerized control system that senses key environmental conditions such as humidity, precipitation, and wind velocity. Most modern terminals collect the drainage from the stockpile area, remove the solids in settling basins, then recirculate the water to reduce water requirements and effluents from the site. Dusting of long-term storage stockpiles can be reduced by spraying the piles with chemical resin or latex binding compounds to seal the surface. These compounds also can minimize erosion of the pile by rainfall. Dust collection with air evacuation systems and cyclone or wet scrubbers can be used at key areas such as rail car dumpers, main conveyor transfers, and ship-loader spouts. The trend in dust control is away from dust collection since most dust collectors are high maintenance items requiring good operator supervision and servicing. Coal handling conveyors are usually open and uncovered. However, in areas requiring special attention they may be covered or even completely enclosed. Dust generation from terminal roads is often a significant amount of the total dust emitted from a terminal. To reduce this dusting, roadways where traffic is heavy can be paved or sprayed by water trucks. Speed limits can be enforced and use of tracked mobile equipment for stockpile handling rather than rubber-tired loaders is encouraged by authorities. Noise Abatement Terminals located close to residential areas are often faced with noise control problems. Noise can be one of the most difficult environmental problems to solve. Usually, use of electrically-powered equipment is encouraged to reduce noise levels. Rail car dumper houses can be totally enclosed to reduce both dust and noise emissions. Diesel locomotives can be fitted with special muffling devices. Green belts of trees surrounding a terminal or the ap-

Jan 7, 1983

By Steve Kral

More than 111,350 mining and construction industry professionals from throughout the world gathered in Las Vegas, NV, March 19-23 for ConExpo-Con/Agg 2002 and IFPE 2002. The triennial event is the Western Hemisphere’s largest equipment show for the quarrying, aggregates, construction and ready-mixed concrete industries. Despite the difficulties in the world economy, ConExpo-Con/Agg 2002 attracted more than 2,450 exhibitors from throughout the world. This was an increase from the 1,882 exhibitors that were on hand for the 1999show. And this year’s show occupied more than 180,225m2 (1.94 million sq ft) of exhibit space at the Las Vegas Convention Center. This was an increase from the160,900 m2 (1.73-million sq ft) occupied at the 1999event.

Jan 1, 2002

When defining a ?megaproject,? one need only to look at Seattle, WA?s State Route 99 Alaskan Way Viaduct replacement project. This $3.1-billion project is one of the largest of its kind in the world, and includes the use of the world?s largest tunnel boring machine (TBM). However, for as large as the Alaskan Way project is ? especially given the size of the TBM being used ? there are several other megaprojects underway around the world. Each has its own challenges that require innovative design techniques and financing arrangements, as well as variations on established tunneling technologies. So it was that 266 tunneling and underground construction professionals ? owners, contractors and engineers ? convened in Seattle in November for the Cutting Edge Conference on Megaprojects. This was the second joint meeting between the Underground Construction Association of SME and the North American Tunneling Journal. The first joint conference took place in April 2012 in Miami, FL and attracted 238 attendees. A third joint conference, to be held in 2014, is in the planning stage. The key reason Seattle was chosen as the site of the megaprojects conference is the Alaskan Way Viaduct project. Before the conference began, many of the attendees were able to visit the project and get a close look at Bertha, the Hitachi Zosen earth pressure balance TBM that is boring the tunnel. In addition, the conference included an exhibit that attracted 20 industry suppliers, up from 10 the previous year in Miami. The 25 presentations during the two-day conference covered all aspects of the tunneling and underground construction of megaprojects. Topics included the Alaskan Way Viaduct project; considerations for procurement and contracting; political risk, financing and insurance; international megaprojects; risk and risk sharing and project delivery. Each session concluded with panel discussions.

Dec 1, 2013

By W. R. Reed

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

Jan 1, 2012

By A. M. Al Taweel, S. M. El Mofty, T. A. Hassan, M. R. Moharam, A. M. Ramadan

The axial mixing characteristics of a pilot-scale flotation column were investigated with the objective of identifying means to mitigate the extent of axial mixing that adversely affects its grade/recovery performance. A wide range of design and operating conditions was investigated and the experimental results, obtained using the dynamic response method, were analyzed using three axial mixing models. The dynamic response of the column can best be described using the axial dispersion model. The results obtained suggest that the value of the axial dispersion coefficient, EL. can be signi6cantly reduced by judicial selection of hydrodynamic conditions and/or the use of column inserts that suppress the onset of hydrodynamic instabilities inherent to the operation of conventional flotation columns. Up to 40% reduction in the value of EL was thus obtained by using spargers that produce more uniform bubble sizes, while up to 30% reductions were obtained by controlling the residual frother concentration.

Jan 1, 1995

By Dan S. Nilsson

When an open pit mine is deepened, more and more waste rock must normally be removed. Techniques for optimization of open pit design are well-established within the mining industry. The recommended method is to choose the open pit alternative with the highest net present capital value of open pit and future underground mining. When the open pit is mined out, the operation must be closed, or, if it is profitable, mining must start underground. When planning an underground operation we experience the same type of optimization problem that occurs when determining the optimal depth for open pit mining. When mining underground the ore body is often divided into a number of areas, blocks or slices, each containing a transportation system with trains, trucks, conveyors, etc. When all the ore within such a part of the deposit is extracted, the operation must be closed, or, if it is profitable, a new transportation must be developed. The question that now arises is: how large a pan of a deposit shall be included in the first development and how much shall be left for future consideration?

Jan 1, 1981

By Rudolf Voigt

Lignite reserves occur all over the world in different climatic regions. This means, that the impact of the hydrologic regime upon mining activities and, vice versa, of the mining activities upon ground and surface water conditions will be different between any two mines. On the other hand, most economically important lignite deposits can be grouped according to principal depositional and structural features described briefly in the following section. These features do allow a preliminary assessments of the nature of ground water problems which may face the mine. The cost of protection against water which threatens a mine, the environmental impact of the appropriate measures to achieve this end and the restraints of population density which both might exclude the most cost-effective approach will govern the project expenditure for drainage work. Whether or not this expenditure can be borne by the project must be established during the feasi¬bility phases of mine planning. So, the somewhat provoking title of this paper does not mean that its question can be answered once for ever. It should rather serve to bring to the attention of the audience the major features of mine water control.

Jan 1, 1985

By O. Schumacher

Guidelines for publication of information defining the amount and grade of resource material available in a deposit are well established in Australasia?s JORC Guidelines, Canada?s National Instrument 43-101 and similar documents in South Africa, Peru, Chile and elsewhere (Table 1). These guidelines provide standards to apply regarding the geologic and geostatistical basis for describing the level of confidence to be assumed for an estimate of the amount and grade of material. All of them provide for a strict distinction between material that has been demonstrated to be economically mineable and that which has not, and all of them provide terms such as ?resource? or ?exploration information? to be applied to data regarding material that has not been demonstrated to be economically mineable. It is not until an economic study has been completed that we are allowed to apply the powerful terms ?reserves? and ?ore? to our deposit material. Indeed, the application of these eye-catching labels immediately tells the reader that an economic study has been completed by a qualified person, and that the results of the study were positive. While extensive guidelines are established for describing the level of confidence in published geologic data, and the nature of the economic study that should be accomplished before using the terms ?reserves? or ?ore?, surprisingly little guidance is provided regarding the process to use, and the level of detail to attain, for estimating capital and operating costs for the study. The intent of this paper is to lay the groundwork for development of suitable guidelines for the cost estimating process. While the codes do not provide specific instructions for the cost estimate, they do provide numerous hints and clues to help determine the level of detail expected and the type of procedure to apply in preparing the estimate. This paper will first review the various codes to gain an insight into the thinking of the drafters of the codes regarding their unstated expectations for the cost estimating process. Based on this review, a series of guidelines are proposed for this purpose.

Feb 27, 2013

By Birger Schmidt

INTRODUCTION Conceptual design of the first Exploratory Shaft (ES-I) for the Nuclear Waste Repository in Basalt (NWRB) began in July 1981; detailed design began in February 1982, and was largely completed by December (RKE/PB, 1983). The intent was to begin shaft construction by January 1983. The site had been prepared at that time, a construction manager selected and on board, the starter hole excavated and lined, and steel casings were under procurement. Government policy changed, however, and construction was halted before the drill rig started turning. Construction is now planned to begin in 1988. ES-I is a part of the site characterization program for the NWRB. The shaft will be used to develop production data and related information relative to drilling shafts at the site near Richland, WA, and to provide access to the repository horizon for site characterization and testing. The early program called for one shaft and some 330 m (1000 ft) of drifting. The program has since expanded to include a second shaft (ES-II) and more extensive drifting and testing. Currently, both shafts are planned to be 1.8 m (6 ft) in finished diameter, but studies are underway to determine if the second shaft should be larger. The drilling method was selected for shaft construction primarily because it offered a significantly shorter construction period than conventional shaft sinking using freezing and grouting. The finished drilled shaft will be lined with a continuous steel lining. Personnel are safer during construction with a drilled shaft than with a conventionally sunk shaft. The drilling method

Jan 1, 1987

By J. D. Potts

Installation of a horizontal air blocking shelf around the inside perimeter of the surface mining drill deck shroud is proposed to improve dust capture. Without the use of this shelf, a strong coanda effect airflow pattern results in dust leakage to the environment, especially at the shroud-to-ground interface. Bailing air exits the drill hole and travels along the drill steel to the underside of the table, where it fans out across the bottom of the drill table and continues down the sides of the shroud. This dust-laden bailing air then strikes the ground and fans out under gaps between the shroud and the ground. The proposed shelf prevents dust-laden air from striking the ground by redirecting it toward the center of the enclosure, where it can be captured. Laboratory tests demonstrated that the shelf reduced dust levels outside of the shroud by 81% under operating conditions consisting of a 1.9:1 collector to bailing airflow ratio, and a 5.1-cm (2-in) gap between the shroud and ground. The shelf was 15.2-cm (6-in) wide and located at a height equal to 2/3 the distance measured from the bottom of the shroud to the bottom of the drill table. The air blocking shelf was also capable of overcoming the adverse impact of vertical leakage along the shroud seams as long as this leakage was confined to an area below the horizontal plane defined by the shelf location.

Jan 1, 2009

By P. D?Elia

Following a study by NIOSH on the availability of teams in the U.S. as well as existing training sites and their capabilities, the Penn State University, leaders of the Pittsburgh Section of SME, providers of mine rescue equipment, and industry sponsors united to establish and make fully functional a student mine rescue team at Penn State University. With the growth of MERD and mine rescue competitive events at Missouri S&T, the Mine Training and Technology Center in PA, and at Colorado School of Mines Edgar Mine, a critical mass of effective training venues were made available to help student teams progress and develop mine rescue skills. The challenges to be met in creating and developing a student mine rescue team will be discussed. The rewards from this type of effort will be the quick capability of graduates from mining engineering programs to be involved in not only mining operations, but industry mine rescue teams and other leadership roles as well.

Jan 1, 2012

This paper investigates the effects of solids concentration and the addition of Dispersant S40 on the flowability of original and ground limestone slurries. A rotational viscometer with a concentric cylinder geometry and a controlled-stress rheometer with a cone-and-plate geometry were used to characterize the rheological behaviors of limestone slurries. The rheological behavior of original limestone slurries (<100 µm) is transformed through different types of flows with increasing solids concentration. The use of Dispersant S40 can improve the slurry flowability by decreasing viscosity and eliminating Casson yield stress. It is therefore used as a grinding aid for the wet ultrafine grinding of limestone. The rheological behaviors of ground limestone slurries vary with grinding from a starting dilatant flow-ability to a resulting pseudoplastic one with an evident Casson yield stress in combination with a thixotropic character. The appearance of pseudoplastic flowability combining thixotropy is related to the fineness of a ground product and its specific surface area, which are both correlated to solids concentration and the additive amount of Dispersant S40. In addition, the accurate rheological characterization of time-dependent fluids is dependent on the instruments used and operation conditions.

Jan 1, 2007

By J. H. Daniel

The reduction of accidents will play an ever increasing role in the mining of coal and hardrock ores as mining operations become more mechanized, the equipment becomes more costly and sophisticated, and as mineral production exploits deeper and more marginal coal and ore deposits. The most effective means to reduce accidents is through the design of mining systems and equipment. Results of safety research by the U.S. Department of the Interior, Bureau of Mines, to design safer coal extraction and haulage systems and to reduce electrical accidents are presented.

Jan 1, 1991

By I. Gombköto, J. Bohm

"In Europe, and therefore in Hungary opening a new mine is harder and harder. Depletion of mines, unfavourable legal and economic changes, and growing public concerns are the main reasons. Social and economic interests require total utilization of mineral raw materials of the operating mines, and furthermore utilization of waste heaps of the former mines. There are 5-6000 waste heaps of the operating and the closed mines in Hungary. 2000 of these waste heaps have already been estimated, and researches show that total amount of waste heaps can be calculated to 1 billion tones. These researches left out of consideration waste heaps exploited and placed in deep lignite mining. In several projects and researches we analysed processing of waste heap and possibilities to use its components. A processing technology for utilizing waste heaps has been developed based on laboratory and pilot plant tests. Great amount of useful materials of quarrying waste heaps can be utilized with this technology. Tests were also done for processing waste heap of a former ferrous metals mining. The developed processing technology contributes to use these waste heaps as aggregate for cement industry, as dielectric and aggregate for construction. The essay presents in details main characteristics of waste heaps, technologies already used for processing waste heaps of quarrying and ferrous metals mining, mass balances and qualitative parameters of the end products."

Jan 1, 2011

"The paper treats the spatial aspect of mine sequence optimization. This aspect is revealed in the context of determination of the optimum number of cutbacks of an open pit mine. Cutback mining is a dominating method currently in base\precious metal mining and it is based on a pseudo-economic discretization of the pit space by using advanced pit design algorithms. The result of the implementation of such approach of pit design is the generation of pit shells, which need to be grouped into an optimum number of cutbacks for maximization of the project value. A mathematical solution of this problem is developed with the utilization of a combinatorial analysis. The solution provides a multi-variant investigation of the optimum mine sequence with the implementation of an author’s method for production scheduling optimization, which uses the Net Present Value as a criterion for assessing the economic efficiency of mine sequencing. A case study is provided for the conditions of a hypothetical open pit gold mine to illustrate the applicability of the approach. The results obtained reveal the complex nature of the variation of the Net Present Value as a function of the cutback geometry. INTRODUCTION The mine sequence optimization in open pit mining is a procedure that predetermines the efficiency of the production scheduling optimization. From a technological standpoint, the mine sequence optimization deals with two aspects – spatial and time. Each of them plays a tremendously important role in searching for the optimum solution of the open pit design problem. Original results on the time aspect of mine sequence optimization are published by Halatchev [2002]. They reveal a wide range of the Net Present Value (NPV) variation for a multi-variant arrangement of mine sequence over time and using a fixed geometry of the cutbacks, which determines the economic potential of a single open pit mine from a deterministic standpoint. The results show a range of NPV variation up to 30% depending on the stripping ratio of the mine. The effect of this variation is mainly due to the implementation of the mine planning principle of waste deferment in the scheduling optimization and using all theoretically possible variants of mine sequence arrangement by the inclusion of the bench sequences over the Life-Of-Mine (LOM) in the production process."

Jan 1, 2015

By C. B. Manula

The application of computers to materials handling problems has recently been investigated by various mining groups. This approach has been found, especially useful where a large amount of alternatives must be investigated prior to arriving at a final decision. These alternatives may be expressed in terms of man hours, units and types of equipment such as trucks or conveyors, or the allocation and operation of proposed or existing haulage facilities. The decision problem becomes especially evident when we consider the mechanical revolution which has flooded the mining industry in recent years. The industry has become highly competitive, with the need to keep low profit materials away from high cost production faces ever increasing. The capital investment required for the highly sophisticated equipment that is necessary to perform this function is generally great, and management is faced with decisions which must all too often be made without sufficient data.

Jan 1, 1967

By Lee S. Richardson

Silicon is usually considered to be a useful metallic alloying element. To be more truthful, it is not a metal at all, but a semiconductor, whose electrical resistance (when pure) is high and decreases with temperature. We will join the metallurgists, at least for this paper, and refer to it as a metal. In its commercially available form, silicon is metallic in appearance, brittle, with a density of 2.33, less than that of aluminum. Silicon dioxide or quartz has a high heat of formation, which not only makes the metal a useful reductant for other materials, but also makes it difficult to reduce from its ore. The melting point is 1412°C, slightly less than steel, but substantially higher than aluminum or cast iron. The alloys of silicon with iron, usually called ferrosilicons, have some unique advantages. The melting points of most alloys are substantially below those of iron or silicon (Fig. 1). The two major compounds formed (FeSi and FeSi2) help somewhat in the reduction of silicon by their energies of formation, but the influence of these phases on the mechanical properties is more important. Four major groups of alloys are made -- silicon metal (>95% silicon), 75-85% ferrosilicon, 50% ferrosilicon, and silvery pig iron (12-22% silicon). The alloys between 50 and 65% silicon and between 25 and 40% silicon are normally avoided because of structural instabilities, presumably of the two compounds, leading to disintegration of the alloys on cooling.

Jan 1, 1974