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By Immo H. Redeker

Tile Asheville Minerals Research Laboratory is a member of the Engineering Research Department of North Carolina State University. The Laboratory is engaged mainly in applied nonmetallic mineral processing research to assist the North Carolina mining industry. A few out of state projects are handled at times. The Laboratory helped to bring the flotation process to North Carolina feldspar, spodumene, mica and phosphate producers and maintains versatile batch and pilot plant facilities at Asheville. It is of interest that North Carolina has now one of the newest and largest flotation plants at Lee Creek where Texas Gulf Sulphur Company produces 10,000 tons of phosphate concentrate per day, and one of the smallest flotation plants at Pittsburgh Plate Glass Company's fiberglass plant in Shelby, North Carolina where $50,000 per year of platinum-rhodium metal is reclaimed from wasted fiberglass furnace refractories in a tiny flotation operation of pilot plant size. The conservation of mineral resources through improved processing methods has been the object of most of the Laboratory's projects. This work has been extremely interesting and rewarding in many instances. Or, the example of projects for Kings Mountain Mica Company it will be demonstrated how waste could be reduced step by step from 20 tons of waste per ton of product to LO tons of product per ton of waste by improved processing methods. Brick, high grade potash feldspar, and silica sand are now produced from formerly wasted materials. AL this time Laboratory work sponsored by three feldspar companies, the State of North Carolina, and the U. S. Bureau of Mines, is aimed at reducing the amounts of feldspar tailings in the Spruce Pine area. Mineral dressing techniques are applied to reclaim saleable mineral products such as feldspar, mica quartz, and to make more uniform material for possible ceramic and other applications. Processes to produce new products such as sand-lime brick, and lightweight foamed autoclaved calcium silicate building products will be tested.

Jan 1, 1969

By G. M. Rao

It has been a universal observation that rich grades of ores and minerals are getting depleted, simultaneously the demands for civilization are ever increasing coupled with occurrence of poor grades of ores and minerals posing a problem to the processing engineers. At the same time, the cost of mining and milling are increasing, creating a situation where the management has to handle and process low grade ores at an economic level keeping environmental stipulations and control to be safeguarded which has been an additional cost for the management to comply with.

Jan 1, 1994

By Ingvar Janelid

During recent years, numerous articles have been published regarding theories and practical applications of sublevel caving. The reason is the great interest this method has created through its possibilities of standardizing and mechanizing operations and equipment. Other advantages are that the method can be adapted to orebodies of different shape, size, strength etc., and especially that working conditions can be made safe and relatively comfortable since all work is carried out in drifts. As is well known, the disadvantages or sublevel caving are that ore recovery hardly exceeds 85-90 % if waste rock dilution is to be kept below 20-30 %. Therefore, the main research and development work has been concentrated on parameters which can affect and reduce these disadvantages. This paper deals only with principles and problems which apply to large, massive orebodies. The problems with narrow, vertical or inclined orebodies are so different that they require a special handling. In my opinion, the intense research and development work during recent years, combined with practical experience, has given enough knowledge of the influence of different parameters, so that normal sublevel caving can be efficiently planned.

Jan 1, 1975

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 Penglu Gan, Jinjie Zou, Chenglang Pan, Xiaowu Tang, Yu Zhao

"The north segment of the Zizhi Tunnel that consists of twin tunnels was excavated at a shallow depth in soft ground using the Shallow Tunneling Method. Based on continuous field measurements, the development histories of surface settlement were analyzed first. The observed development process could be roughly divided into three stages and the influence of river was evidenced. Transverse and longitudinal surface settlements above the twin tunnels were then fitted with empirical models. The obtained trough width parameters in transverse and longitudinal direction (it and il) and the volume loss (VLs) were presented and discussed. Additionally, surface settlement was compared with the crown settlement. The relationship between surface and crown settlement behaved in two different ways inside and outside the river-affected region. The findings in this project give references for predicting surface settlements in similar tunneling condition. INTRODUCTION Nowadays tunnel construction has become a major way of utilizing underground space in many large cities. The ground deformation will be inevitably induced in the tunneling process. Engineers should always be careful about excessive deformation that may damage adjacent structures. For shallow tunnels, controlling ground deformation turns to be more risky. Since soil arching is not completely formed in the shallow tunneling, settlements can easily develop from tunnel crown to ground surface.A conventional tunneling method named Shallow Tunneling Method (STM) has been developed and widely applied to constructed shallow tunnels in China. The major difference between this method and the New Austrian Tunneling Method (NATM) is whether considering self-supporting capacity of surrounding ground or not. In order to reduce the disturbance of surrounding soils, several guidelines are highlighted in this method, including advanced pipe forepoles, strict grouting, short excavation length, strong support, quick closure and frequent measurements (Fang 2012). Nevertheless, the ground deformation is still hard to control and becomes a concerned problem, mainly because ground settlement has some regional features and largely depends on the detailed excavation methods (bench cut method, multiple heading method, etc.) and ground condition (sand, clay, decomposed rock, etc.)."

Jan 1, 2016

By Drew F. Holbrook

Most of the siliceous rocks of the Arkansas Novaculite are novaculite, but they also include some chert, siliceous shale and, rarely, sandstone. Novaculite is defined as a homogeneous mostly white or light-colored rock, translucent on thin edges, with a dull to waxy Juster, and comprised almost entirely of microcrystalline quartz. The most plausible theory of origin for novaculite is that primary silica from submarine volcanism was picked up by organisms and deposited as amorphous silica, which was subsequently converted to microcrystalline quartz (novaculite) through diagenesis. The Arkansas Novaculite crops out over an east-west distance of 200 miles in the Ouachita Mountains of Arkansas and Oklahoma. Three divisions of the formation have been defined: a Lower Division, almost entirely massive light-colored novaculite; a Middle Division of interbedded dark chert and shale; and an Upper Division of massive calcareous novaculite. The Lower Division and most of the Middle Division are Devonian in age, and the remainder of the Middle Division and all of the Upper Division are Mississippian. The massive novaculites of the Upper and Lower Division attain their maximum development along the southern and central outcrop belts of the formation in Arkansas, and it is these rocks that are the source of current silica production. The calcareous novaculite of the Upper Division weathers readily to a light-colored, porous, less brittle rock, and in places to tripoli deposits. Currently tripoli is mined from a single deposit near. Hot Springs, Arkansas, and the rock is processed for highly specialized filler and abrasive applications. In the vicinity of Hot Springs, Arkansas, certain novaculite layers from the Lower Division with unique textural characteristics are quarried and processed into whetstones. Several small quarries produce this rock for two local and one out-of-state whetstone-fabricating plants. Chemical analyses of composite samples of novaculite from both the Upper and Lower Divisions taken at widely separated localities average 99 percent SiOz indicating a substantial resource of high-silica rock.

Jan 1, 1978

By S. Henley

There is much in common between the requirements of open-pit mining and quarrying operations. Both involve the extraction of large volumes of material from surface excavations. The principal differences are of degree: open-pit mining of materials such as coal or gold generally involves the extraction of only small volumes of 'mineral' and large volumes of waste-they are operations with very high stripping ratios, and are made viable only because of the high unit value of the extracted mineral. In quarrying operations, the unit value of the mineral - sand, aggregate, limestone, or clay - is much lower, but stripping ration Are also lower. Thus the same techniques of geological modelling, reserve estimation, and pit planning are applicable, as is shown in two examples from the British quarrying industry. In each case, a primary requirement is the definition of production volume or tonnage. Sometimes, this need may be addressed simply by the use of a survey data processing package. However, in other cases, such as the two examples addressed in this paper, of sand and clay quarries, detailed assessment of the variation of mineral grades is a vital part of the exercise, and simple volumetric modelling cannot in itself be sufficient. In these cases, a block model approach using simple logical and numerical post-processing is also required to obtain required parameters for commercial classification of the products to be extracted. Pit designs themselves may be optimised by use of algorithms such as Lerchs-Grossmann, but the value of mineral produced can be dependent on factors other than its grade in any one part of a single pit, and the 'optimised' pit itself must be considered only a good sub-optimal. Given the right degree of healthy skepticism, and a software package with sufficient flexibility to be adapted readily to the rather different requirements of the quarrying industry, there is no reason why the quarrying industry should not benefit from the many years of investment in mining software technology.

Jan 1, 1989

By Andrew Burton, Damian Schofield, Jeremy Noond

This paper will introduce and discuss a range of techniques that utilise new developments in Computer Graphics (CG) and Virtual Reality (VR) for the investigation of incidents and accidents in mining environments. The future of mining safety may not be totally led by the demands of the mine operators, but sometimes by the academics, commercial software developers and legal pioneers who generate new ideas and products and set admissibility precedents which may change the way certain traditional investigative operations are performed. In any accident investigation the outcome from the investigating team is often a complex affair and the results of the investigation are often reported in large, convoluted documents. Computer-generated forensic reconstructions allow investigators to present accident scenarios in an accessible and easily understood, visual manner. Surveys in the US have also shown that people have increased recall of computer-generated images over many other forms of evidence. The AIMS Research Unit in the UK have been pioneering the use of Computer Graphics (CG) and Virtual Reality (VR) technology for both industrial and road traffic accident reconstruction. This paper and accompanying presentation will contain examples of forensic reconstructions developed by the authors that explain some of the methodologies used to ensure admissibility of this type of digital evidence. The paper will contain a number of case studies based on UK and International industrial accidents. The paper will focus on how AIMS Research is extending the capabilities of the accident reconstructions created to take advantage of the latest developments in VR technology. As digital technology makes its impact within professional and commercial fields, computer generated forensic reconstructions will form important admissible evidence in the courtrooms of the future. The technology will also make a great impact in the way we train our workforces, with highly visual three-dimensional (3D) interactive training tools becoming the norm. Acceptance by the public, courts and workforce is an important issue, and implementation strategies must be considered carefully.

Jan 1, 2002

By Jon “Ike” Isaacson, Frank Perrone, Eric Prantil

"Tunneling through an urban environment carries many inherent risks to the immediate local infrastructure and subsequently to the project stakeholders. On the CQ031 Contract of the East Side Access Project in Queens, New York, twin 22.5’ diameter Herrenknecht Slurry TBMs were mined within close proximity to many infrastructure assets, with cover of less than half a shield diameter at times. Multiple public bridges and critical railroad infrastructure including catenary poles and signal towers supporting the busiest rail interlocking in the United States required underpinning systems. The support program for these structures was refined over the course of the four tunnel drives. It is the intent of this paper to show how the interaction between the temporary structures, instrumentation monitoring plan, and risk assessment program melded to provide a system which the owner, contractor, and designer relied on as a tool to ensure the project success without impacting the public surroundings. PROJECT BACKGROUND The East Side Access (ESA) megaproject located in New York City, N.Y is a multi billion dollar program for the Metropolitan Transit Authority Capital Construction (MTACC) with the main goal of bringing the Long Island Railroad (LIRR) commuter rail to Grand Central Station located in the heart of Midtown Manhattan. When completed, the project will significantly reduce congestion both into and out of Penn Station, the current terminus of the LIRR. In order to accomplish this, multiple contracts of varying scope are required to operate simultaneously in both Queens, N.Y and Manhattan. In 2009, the CQ031 Queens Bored Tunnels Contract was awarded to the joint venture of Granite Construction Northeast, Traylor Bros. Inc., and Frontier Kemper (G.T.F). The main scope of this contract was to excavate four segmentally lined soft ground tunnels underneath the Sunnyside Rail Yard in Queens, New York. Additional scope of work included the construction of a tunnel approach structure, electrical substation, and multipurpose ventilation and egress facility."

Jan 1, 2016

By Wayne Charlie, Joseph P. Martin

INTRODUCTION Typically, uranium mills produce slurred tailings which are transported by pipeline to a tailings impoundment. The slurried tailings contain about 250 solids (75% liquids) by volume and, depending on the milling process, have a high or low ph. Despite decanting water from the tailings pond and losses by evaporation and seepage, Staub (1978) estimates that for lined impoundments over half of the input water is stored in the tailings. As long as the impounded tailings remain in a loose and saturated state, potential hazards exist and include potential for short and long-term seepage from the impoundments and the potential for large scale release and movement of liquified tailings should an embankment fail. The breach of an earthen dam on July 16, 1979 at Church Rock, New Mexico, and the subsequent release of 100 million gallons of water and liquified uranium tailings, underlines the potential hazard. Loose saturated tailings also have a high potential of liquefaction during earthquakes (Charlie and Wardwell, 1979; Martin, Finn and Seed, 1978; and Mittal and Morgenstern, 1976). If the tailings could be dewatered, the liner's integrity would become less critical, longterm seepage and settlements would be greatly reduced. In addition, the potential for tailings liquefaction from an embankment failure or earthquake would be greatly reduced. This paper reviews the concept, criteria, and design of various proposed interior drainage systems to dewater the tailings after deposition. ADVANTAGES OF INTERIOR DRAINAGE The primary purpose of interior drainage systems for uranium mill tailings impoundments is dewatering the tailings as rapidly and as thoroughly as possible. The expected benefits of this new technology are: • Reduction of potential seepage losses by decreasing the hydraulic head. • Reduce earthquake liquefaction potential of the tailings by inducing non-saturated conditions and/or lowering the water pressure. • Reduce the potential for large-scale release and movement of tailings should an embankment fail. • Stabilize the tailings to permit early reclamation. • Recovery and potential recycling of tailings liquid. • Inhibiting long-term seepage out of the impoundment by inducing nonsaturated conditions to provide capillary suction in the tailings.

Jan 1, 1980

By T. M. Karppanen

Shotcrete is used both in mining and tunnelling for supporting rock. Both dry and wet processes are used for shotcreting, and each produces good quality concrete. Thick shotcrete layers function as a concrete arch supporting loose rock. Thin layers prevent relative movements between the blocks of rock due to the fine concrete in the cracks and joints. No progressive fallouts occur since key blocks are kept in place. Rockbolts are often used together with shotcrete in order to create an arch around the tunnel making the rock to support itself. Shotcrete is sprayed either manually or by means of mechanized equipment. The aim is to spray required the layer thickness in one pass and with a minimum amount of rebound. Sprayed layers should also be as even as possible. The tip of the nozzle should be moved in circular movements. The shotcrete should be sprayed at a right angle to the rock surface; the optimum distance from the nozzle to the application surface must be found by experiment. In a mine shotcreting forms a materials handling system which includes batching, transporting and the actual shotcreting. The equipment used vary depending on the spraying method, mining conditions and the location of the mine. Shotcreting is performed with a purpose-designed unit in most cases where operation is mechanized. The shotcreting unit consists of a spraying machine with a hose and a nozzle, an additive system, a manipulator and a mobile carrier with all the necessary controls and accessories. The key element of the unit is the shotcreting manipulator which holds and guides the nozzle as required. The manipulators currently in use are hydraulically operated, and their remote controlled booms are also often called robots. These manipulators have enabled users to increase their output capacities, to remove the operator away from unsafe areas and from the influence of dust and rebound. Furthermore, they improve the shotcrete quality and reduce shotcreting costs.

Jan 1, 1989

By Jerzy F. Sobala

Large - scale tests at the Polish Safety in Mines Institute /established in 1925 as "Barbara" Experimental mine/ performed in underground and surface experimental galleries, simulating conditions in roadways in mines, are the basic source of knowledge about development and propagation of explosions. Investigations up to 1973 were performed under the Institute's former research director Professor W.B. Cybulski s supervision, whose handbook concerning combating of coal dust explosions in collieries has been also published in the U.S. (2), and are continued until now. For investigating explosions the "Barbara" Mine disposes of 170 m /7.5 sq m/, 200 m /5 sq m/ and 400 m /7.5 sq m/ underground gallieries as well as of 10 m, 25 m, 44 m and 100 m surface galleries. For example, in the 200 m gallery more than 5200, and in the 400 m gallery - more than 2200 test explosions have been performed. Basing on determination of explosion hazard in roadways in collieries and on data of scientific research performed at the Safety in Mines Institute, the strategy of combating the explosion hazard in mines was elaborated; it includes mainly diminishing of coal duet. deposition in roadways, and -because of the possible inefficiency of this safety means in some roadways in mechanized collieries -- the introduction of three additional defence lines against coal dust explosions. It should be mentioned that at the "Barbara" Mine the problem of coal dust explosion initiation was elaborated as contract work for the U.S. Bureau of Mines. The main aim of this paper is to discuss some aspects of methods and measures for combating coal dust explosion hazard in highly mechanized mines in the Polish mining industry where in some roadways explosible coal dust is present, but it is not the aim to evaluate the effectiveness of methods and measures for diminishing the make-up of coal dust and coal dust deposition rates in roadways.

Jan 1, 1980

By William Moser, B. P. Shagula

INTRODUCTION Every day mine management and mining personnel face the threat of a possible mine disaster or fire. Their ability to deal with such a situation safely and effectively depends on the level of emergency preparation developed and maintained. After conducting numerous informal evaluations or audits at different mine sites throughout West Virginia (as well as other states), the authors concluded that many mining operations are not prepared to handle a fire situation. The results of the audits indicate that while most mines are in compliance with federal and state legal regulations regarding levels of emergency equipment, water systems and training sessions, these levels - particularly in the area of fire training - are probably not sufficient to enable the mine employees to effectively combat a fire in its early stage. This paper will present the authors' recommendations for designing and maintaining an efficient mine emergency preparedness Program and an overview of the curriculum of the mine fire training Program currently being conducted. MINE EMERGENCY FXEPAREDNESS PROGRAM The Mine Emergency Preparedness Pro- gram (MEPP) is a management tool developed by the Mining Extension Service at West Virginia University and was designed to assist company personnel in effectively managing a mine emergency operation. The program goes beyond the traditional and required training of mine rescue teams by offering a complete emergency operations package. Included in MEPP are suggested approaches for training and organizing all personnel, ideas for developing plans of action concerning transportation, security and communications. The MEPP program may also be used as to assess present readiness levels. While the MEPP program is designed to address all types of emergency operations, the authors are convinced that emergencies involving mine fires are the ones of greatest concern and so are concentrating their efforts in that direction. Incidents where fires are involved seem to be increasing in frequency and are extremely costly to control if allowed to go beyond the incipient stages. With a proper emergency preparedness program in place and properly trained and equipped fire brigades, the authors feel that it is possible

Jan 1, 1992

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 P. Somasundaran, F. F. Aplan

The Formative Years Douglas Winston Fuerstenau was born December 6, 1928 in Hazel, SD to Edwin Arnold and Hazel Pauline (Karterud) Fuerstenau. His father, of German extraction, was a farmer and, later, a cabinet maker, while his mother, of Norwegian lineage, was a school teacher. His parents are still alive today at ages 91 and 88, respectively. Two younger brothers, Richard and Maurice and a sister, Jean, completed the family. The family first lived near Watertown and later in Lemmon and Mobridge, SD. The 1930's were a difficult period for any family in South Dakota. A decade-long drought made this a part of the dust bowl, which together with a serious infestation of grasshoppers (the locust plague described in The Bible), and the world-wide depression, made living difficult for all. In spite of these privations, Doug has many happy memories of his childhood which can be attributed to the resilience of youth and a strong family structure. He has fond memories of summers spent with his cousins on family farms where the children were introduced to farm chores at an early age. When he was old enough, he worked in a grocery store after school. At the age of 14 he spent the summer hearding 2,000 sheep near Lemmon, SD as his contribution to the war effort in that labor-short period. He remembers well the dust storms of the 1930ts, the destruction at his grandmother's farm by tornado, pulling weeds on the farm, threshing grain with a monstrous steam-driven machine and such pleasant childhood activi- ties as fishing for bullheads, hunting for rabbits, searching for arrowheads in newly plowed fields, and ice skating in the winter. Early in life his parents instilled in him a strong work ethic, a love of learning and the need for a good education. In 1943, the family moved to Rapid City, SD. With a population of 13,000, it was

Jan 1, 1989

By T. C. Rao

The quantum of coal fines below 6 mm in run-of-mine (ROM) coal has been increasing due to progressive mechanization of mining methods which has created a substantial incentive, worldwide, to develop suitable fine coal beneficiation techniques. The majority of the efforts have been directed toward reduction in ash/sulfur contents in clean coal. The beneficiation techniques may be broadly grouped as those based on specific gravity and surface property. The processes, which use heavy medium cyclone, water-only cyclone, concentrating tables, and spirals, belong to the former group while the latter group encompasses froth flotation, column flotation, oleo- flotation, and oil agglomeration. In almost all the gravity based techniques, it has been noted that a classification step prior to beneficiation is essential for effective treatment. In general, the effect of design and process variables on the performance of these units and also the quantification of the processes have been the main areas of research and development. In froth flotation, efforts throughout the world have been mainly to understand the effect of variables and to optimize the process. Quantification of the process has been attempted through kinetic studies and mathematical modeling. The efforts have led to the development of new reagents, machine designs, and flowsheets for a specified objective. The attempts so far with the column flotation and oleoflotation processes have indicated a great potential. Extensive R&D efforts are in progress to understand as well as to commercialize the processes. The efforts in the oil agglomeration process have been toward substantiating the inherent merits of the process by developing cheaper bridging liquids and technology to recover and reuse the oil to make the process commercially viable. Modeling of the process has also been attempted to predict the yield and size distribution of the agglomerates. This paper reviews and summarizes the recent developments in the science and technology of fine coal beneficiation processes. The current trends in R%D efforts for these processes are also highlighted.

Jan 1, 1987

By Duk-Won Park

Ground water has been a problem in underground mines (Anon., 1981; Aughenbough, 1973; Stansbury, 1981). Water migrates from water-bearing formations and surface water bodies such as lakes, ponds or creeks into the underground workings through fractures and cracks. As a result, under- ground workings become plagued with the necessity of having the water pumped out in large quantities. Underground workings become flooded when unexpected amounts of water flow into the openings, especially when mines use pillar extraction or longwall mining methods. It is difficult to detect water bodies above the coal mine roof before water problems take place. The resistivity method was used as a method for detecting water saturated rock layers and bodies of water above the roof of a coal mine in northern West Virginia, where the multiple seam mining method was being used.

Jan 1, 1983

By L. F. Delgado

Environmental and cost pressures sparked renewed interest in gravity separation. Industrial sands in Mexico are generally processed by screening, desliming, and flotation. Gravity separation with spirals was evaluated as an alternative to flotation in order to lower operating costs and decrease water pollution. Outstanding operating results are obtained in glass and foundry sand operations, plus a more competitive position for Mexican producers due to lower operating costs. Coal fines, generally recovered by flotation, have the same cost and environmental advantages when processed with spirals.

Jan 1, 1994

By Rick T. Richins

Despite what may be overwhelming evidence that natural degradation of cyanide and cyanide attenuation in hydrogeochemical processes are capable of reducing or eliminating potential water quality problems associated with heap leach facilities, the recent sharp increase in the price of gold and wide interest in the cyanidation process has focused all regulatory eyes on cyanide leaching. Regulations continue to increase, design criteria are more strict, and detoxification requirements approach or exceed the level of detectability. Current governmental regulation of mining and milling operations using cyanide varies considerably from state to state. The lack of regulatory consistency at this level is largely attributable to the current Bevill Amendment exclusion of mine wastes as potentially hazardous wastes, the undefined status of the Environmental Protection Agency's ongoing mine wast study effort, and the mining industry's reluctance to develop a consistent policy regarding state versus federal mine waste regulation.

Jan 1, 1998

By Michael M. Donahue

"The public interest -- as opposed to the narrow interests of particular shippers -- will also benefit from the establishment of adequate revenue levels and the revitalization of the railroads. And this is particularly true with respect to the transportation of coal. "

Jan 1, 1981