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By M. Karmis

"The process of coal mining, as indeed of the mining of any stratified mineral, is inevitably followed by some degree of sinking of the superjacent strata and consequently of the surface." Royal Commission on Mining Subsidence, Second and Final Report, London, 1927. INTRODUCTION The above statement was used to describe mining subsidence in the classic report of the "Royal Commission on Mining Subsidence," published in 1927. In fact, this phenomenon has been recognized in Britain since the early fifteenth century, as revealed from court records of disputes and litigations related to property damage above mine workings (Shadbolt, 1978). The first attempts to investigate and analyze the mechanisms associated with mining subsidence, however, date back to the 1800's and were pursued by Belgian Engineers. This research effort was initiated as a result of the widespread movements and subsequent structural damage suffered by the City of Liege in the 1820's. The most notable achievement of the Belgian school of that era was he publication of Gonot's treatise "Loie de la Normal" in 1871 (Gongt, 1871).

Jan 1, 1982

By Kenneth Savidge

With the recent demand for increased coal production there has been a corresponding increase in the horsepower of the shearing machines. The resultant increase in the machine haulage pull has heightened the incident of haulage chain breakage resulting in machine downtime, but more seriously the danger to face personnel. This paper discusses the application of chainless haulage to longwall mining and describes the systems currently available.

Jan 1, 1978

By Thomas Schwind, Benedikt Grau, Angelos Gakis

"In Crossrail’s Farringdon station, compensation grouting was successfully utilized to mitigate the surface settlements induced by the tunneling works. The main focus of this study was the platform tunnels, which were approximately 300m long each and were enlarged to platform size using sequential excavation method (SEM) from the existing TBM running tunnels, initially supported using sprayed concrete linings. The rear grouting injections were carried out at a typical distance of minimum 5m above the completed, fully strengthened shotcrete lining hence inducing some additional stresses. In-tunnel monitoring using surveying targets was performed systematically to ensure that no excessive distortion of the initial shotcrete lining occurred. 3D finite element analyses were utilized to back calculate the actual “effective” pressure that was imposed on the completed shotcrete rings against the additional measured in-tunnel displacements due to the compensation grouting episodes. Additionally an assessment of the theoretical, “maximum” allowable grouting pressures that would lead to overstressing of the lining is presented. INTRODUCTION As part of the back analysis performed for the SEM tunnels in Farringdon station, an investigation of the effect of compensation grouting on the two constructed platform tunnels was undertaken. The platform tunnels were 10.6m high by 11.4m wide and approximately 300m long each. They were enlarged to their final shape from the existing TBM tunnels using SCL methods. This study utilized 2D and 3D finite element (FE) analyses in order to back calculate the observed tunnel crown displacement, assessing the equivalent grouting pressures during the rear injection episodes of the concurrent grouting operations. The results provide a useful reference for the order of magnitude of the grouting pressure load cases that can be applied in the numerical simulation of similar cases. Part of the results presented in this paper, were derived by the second author as part of his Master of Science thesis in Technical University of Graz."

Jan 1, 2016

By J. W. Oberholzer, C. F. Meyer

The increased use of continuous miners to extract thicker coal seams has necessitated the use of enhanced ventilation systems in the headings. Due to the increased face size, more ventilation is required to effectively dilute the liberated methane down to acceptable levels. If more air is directed to the face an increase in the entrainment of dust creates an increased potential for workers to be exposed to dust. To enable the ventilation systems to reduce the methane levels and the levels of the airborne dust the ventilation systems in the heading have to be carefully designed. The matter is made more complicated through the use of other ventilation methods like jet fans, air-moving sprayfans on the continuous miners and high capacity scrubbers on the continuous miners. To enable the design of a balanced ventilation system in seam heights of over five metres requires methods that consider the system in a three- dimensional manner rather than in a two-dimensional fashion. Through the use of computational fluid dynamics (CFD) coupled with appropriate methods of taking underground face ventilation readings these problems can be solved in a cost effective way. Using computer modelling, ventilation methods can be designed and assessed instead of using costly underground trials to test the alternatives. Use of this system has led to a higher level of ventilation design as well as a more effective method to combat the health and safety hazards in coal mine headings.

Jan 1, 1995

Jurist, educator and historian Neil Reynolds will be the keynote speaker at the National Mining Hall of Fame's 11th annual induction banquet on Sunday, Oct. 11,1998 at the Pointe Hilton Resort in Phoenix, AZ. Reynolds is Municipal Court Judge for the City of Leadville, CO, home of the National Mining Hall of Fame & Museum, and a fifth-generation resident of the community. His family staked mining claims on nearby Mount Massive in 1862. Judge Reynolds is a fulltime faculty member at Colorado Mountain College, Chairman of the Lake County Historic Preservation Advisory Board and practices law in Leadville. In announcing the speaker, Board Chairman Richard Moolick said seven inductees into the National Mining Hall of Fame will join 138 mining greats previously honored in the annual ceremonies. This year's inductees will be enshrined by Thomas Falkie, president and chief executive officer of Berwind Natural Resources of Philadelphia, PA. Moolick also announced that Jeffrey Clevenger will be the master of ceremonies for the induction banquet. Clevenger is executive vice president of Cyprus Amax Minerals, Englewood, CO and president of Cyprus Climax Metals, Tempe, AZ. A cocktail reception at 6:30 p.m. will precede the black-tie (optional) dinner, to begin at 7:30 p.m. For additional information, contact Esther Mellott at 719 486 1229. Here are the biographies, then, of this year's seven inductees to the National Mining Hall of Fame & Museum.

Jan 1, 1998

By Allan E. Hall, Stephen G. Hardcastle, Lucien D. Nel, Jean-Paul Saindon

A description is given of the investigation conducted at Sherritt Gordon's Ruttan Operation in Manitoba during 1986. Gas and dust concentrations were measured in the exhaust air of the major working sections to assess the potential for recirculating exhaust air into the intake air in winter to reduce heating costs. The results indicate that there is excellent potential to significantly reduce winter heating costs by controlled recirculation of exhaust air. Gas and dust concentrations vary significantly during the working shifts but have consistent trends from shift to shift and day to day. The variations in gas concentrations have similar trends but no single gas could be reliably used to predict the variation of the other gas or the dust concentrations. Dilution and the other effects which reduce pollutant levels as the exhaust air returns to surface indicate that recirculation should take place as close to surface as possible, subject to the economic constraints of the airway construction required and the extra fan energy required for the longer recirculation path. Recommendations are made for the choice and positioning of air and dust monitoring sensors and the logic of a control system. Economic analysis of the results indicates that controlled recirculation is viable at an existing mine with a pay back period of approximately two years. Incorporation of a system into a new mine at the planning stage would significantly shorten the pay back period.

Jan 1, 1987

By Thomas G. Langton

The demand for mineral raw materials, especially in the major industrialized nations, has grown rapidly during the past three decades. One consequence of this growth has been an increasing reliance by the large industrialized countries upon nondomestic mineral supplies. These mineral supplies, to a large extent, have been developed by capital from the major industrialized countries. Until recently, most foreign mining ventures were either wholly-owned subsidiaries or joint ventures between two or more mining companies. The recent rise of economic nationalism has substantially changed the business climate and parameters under which foreign investors operate. This paper describes some of the underlying reasons for this change and notes how investors have adapted to the new business conditions.

Jan 1, 1974

By R. Y. Wan

Recent research efforts have shown have shown selective solvation extraction of a gold cyanide ion-pair complex from alkaline cyanide solution is possible with organic phosphorus esters. These alkyl phosphorus esters such as tributyl phosphate (TBP) and di-n-butyl n-butyl phosphonate (DBBP) can selectively load gold to rather high levels, even in excess of 30 gpl. However, traditional stripping techniques are not particularly effective. In this regard, gold recovery by direct electrolysis of the organic phase has been found to be an interesting possibility. Further, the rate of direct electrodeposition from the organic phase can be improved significantly by using an aqueous/organic mixture. Direct electrodeposition of sheet gold from loaded DBBP was successfully accomplished at a current density of 8x10 4 amp/cm2 and 55°C from such a two-phase mixture with the aqueous phase as the continuous phase. No appreciable degradation the DBBP was found after 5 cycles of extraction and, electrodeposition. Finally, the applicability of the process strategy for an industrial situation was demonstrated by the successful treatment of waste gold cyanide electroplating solutions.

Jan 1, 1986

By W. F. McDermott

The Iron Ore Industry has perhaps seen more varied and drastic changes in its approach to crushing and grinding in the last 5 years than any of the other mineral industries, Multimillion ton per year plants have become common place. Centralized control and computers have become an established benefit. Autogenous grinding along with a variety of rod and ball grinding flowsheets are in use. This morning I will discuss a few of the more important and new concepts in the control of these crushing and grinding circuits.

Jan 1, 1970

By J. Trimble, B. M. Davis, D. McClure

During initial mining operations at the Colosseum gold mine, discrepancies between the average blasthole grades and mill-head grades were quite large. In December 1987, mill-head grades averaged 39% lower than corre¬sponding estimates from the blastholes. The correlation between average blasthole grade and mill-head grade had an r-value of 0.015. The magnitude of the discrepancy and the lack of correspondence between estimated and actual grades led to a series of investigations of the sampling system, the effect of blast movement of the ore, and the estimation methodology. The discrepancy between blasthole grades and mill-head grades had been reduced by about half on a percentage basis at the conclusion of these studies. Ongoing studies have produced changes that reduced this discrepancy to its present level of less than 10%. Geology The Colosseum mine is within the Clark Mountain mining district about 68 km (42 miles) southwest of Las Vegas, NV in San Bernardino County, CA. Gold mineralization at the deposit is hosted in two 152 m x 213 m (500 ft x 700 ft) interconnected, rhyolitic intrusive breccia pipes that intruded Pre¬cambrian crystalline basement rocks and overlying Paleozoic marine sedimentary rocks. Subsequent erosion (deroofing) of all of the Paleozoic section and a portion of the Precambrian section has exposed the pipes to the present level (probably a significant depth in the original breccia pipe system). Lithologies exhibited within the breccia pipe complexes include rhyolitic felsite, and breccias of felsite and wall/ country rock. Breccia types grade from felsite plus Precambrian granite-gneiss fragments in an aphanitic felsite matrix to crosscutting breccias of felsite, Precambrian granite-gneiss, and Paleozoic sedimentary rocks in a matrix of finely comminuted material of the same composition. All the lithologies in and around the breccia pipes exhibit moderate to intense quartz-sericite-pyrite alteration, with sericite and pyrite the dominant visual alteration minerals. Gold at the Colosseum mine is generally submicroscopic and associated with sulfide mineralization, chiefly pyrite. It occurs as free gold, with minor alloyed silver. It is primarily in contact with pyrite in fractures or along pyrite grain edges. Secondarily, it appears as isolated particles in quartz and other gangue minerals but spatially always close to pyrite, and rarely as particles encased in euhedral pyrite. The pyrite mineralization and minor base metal sulfides occur in three distinct styles: as disseminations, as open space or vein/fracture filling, and in breccia clasts replacing dolomite. The pyrite megascopically ranges from absent to 30% of rock volume within the breccia pipes. Although the gold at Colosseum is apparently spatially and geochemically associated with pyrite, there is only a general proportional relationship between pyrite content and gold content. Sometimes, a high volume percentage of pyrite has only geochemically anomalous gold. This makes visual pyrite only a general grade control tool and not a specific tool. This further makes the ore control process at Colosseum all the more difficult. Initial grade control procedure Initial grade control was based on blasthole samples collected in two stages by an "automatic" sample collection device (rocket sampler). A sample was collected for the top 3 m (10 ft) in a hole. The bag was then changed so that a sample was collected for the lower 3 m (10 ft). Each sample was prepared and fire assayed to determine the grade. Large discrepancies were sometimes noted in the assays of top and bottom samples. The samples were averaged together and a plot was made showing the blasthole locations and their associated grades. Discrimination between ore and waste was based on as-

Jan 1, 1989

By H. C. Verakis, T. E. Lobb

During the past decade, approximately 5 billion pounds of explosives were used annually in the United States. Most of this quantity of explosives was used by the mining industry, with coalmining being the dominant application for explosives. Considering the large amount of explosives used, the accident safety record for the mining industry has improved significantly over the past several decades. Although blasting accidents usually represent a small percentage of the total number of mining accidents, they continue to occur and the severity of these accidents is disproportionately high compared to the other mining accidents. This paper is an analysis and summary of mine blasting accidents over the past several decades as they relate to surface coal mine operations. A compilation and review of surface mine blasting accidents from1978 through 2001 was made. The accident data was examined to identify the trends and primary causes, which continue to be blast area security, fly rock, premature blast, and misfires. Approximately 46percent of the causes of surface coal mine blasting accidents are attributed to blast area security, while fly rock, premature blast, and misfires represented an additional 50 percent of the causes. Accident categories were established based on the cause of the accident or the activity that was taking place when the accident happened. A discussion of the accident data is presented to increase hazard awareness and to emphasize safe blasting practices and MSHA requirements concerning mine blasting operations.

Jan 1, 2003

By Richard Keith Corbin

INTRODUCTION The purpose of this paper is to assist explorationists and entrepreneurs in deciding whether to invest in gold mining concessions in lesser developed countries (LDCs) and, if so, in deciding which LDCs provide the best opportunity. The first decision is difficult in the face of common notions that foreigners are not welcome - only their money; that the best gold deposits were worked out long ago; that even if you survive the mal- aria, and in spite of 51% control by a national partner, you manage to profit from a new discovery, they will tax your operation to death, or worse yet, nationalize it. Close scrutiny of what happened to foreign investors in LDCs during the “Mexicanizationt” of the 1930's through the "Zambianization" of the 1970's shows that many of these concerns are well-founded historically. But the trend of knowledgeable writers over the past decade seems to be away from this gloomy foreboding, and towards a cautious optimism, based on recently perceptible metamorphoses in certain LDCs' conditions and attitudes. If the explorationist or entrepreneur decides to seize on this apparent opportunity, the second decision -- which of these certain LDCs to invest in -- is doubly difficult, because of the formidable tasks of coming up with a rating system to provide rational comparison, and then gathering enough current, reliable information to apply. To assist in these tasks, a suggested rating system and case studies, respectively, follow a brief review of recent writings on the subject

Jan 1, 1987

By Kent S. Roessler

The Bureau of Mines is currently investigating the geophysical application of Tomography to monitor leachate during in-situ mining. Determining the location of the leachate is important for both economic and environmental reasons. By analyzing a sequence of tomographic images, we can determine where highly permeable/fractured regions are located and hence, major flow paths. Since BOMTOM (Bureau Of Mines TOMography - Tomographic Reconstruction Program), and BOMCRATR (Bureau Of Mines Curved RAy Tomography - Tomographic Reconstruction Program) are sensitive to user-selected ray path arrival times, we are also investigating the use of neural networks to automate the process of recognizing this feature. This paper presents a technique for detecting fracture zones and their orientations in a region between two boreholes, by using a motion analysis study of a sequence of tomographic images. It also addresses the need for an automated/unbiased method to pick crosshole seismic arrival times using a trained neural network. In exploration geophysics, the picking of first break arrivals represents a pattern recognition task. The neural net paradigm has proved to be a good method of solving this type of task. To pick the first arrival peak of a trace, the network is trained with a set of known (user selected) first arrival peaks by creating a binary image of a set of traces. Once trained, the neural net correctly picked first arrivals of the remaining traces in the set.

Jan 1, 1992

By G. Milojcic

The opencast lignite mines in the Rhinel and Di strict/Germany are equipped with the continuously operating bucket-wheel excavator - conveyor - spreader system. High productivity requires large capital expenditure on main mine equipment as a precondition for efficient mining. In operation, the technology employed leads to a particular cost pattern which is quite different from that of other industries. Labour, auxiliary equipment and mobile vehicles are the most important cost factors which can be controlled by the management. In this respect information processing computer systems are used for systematical and interpretable representation of operational tasks and jobs both in planning and work preparation and in recording the operational data describing the work result and the use of resources. Another aim of the project is to relieve the middle management of major part of its administrative routine work. Job-related work planning and data recording open up various possibilities of analyzing the operational procedures. This analysis shows, for example, what auxiliary machines are particularly suitable for specific tasks, and working groups can be organized so as to take account of the different skills of individual employees for the sake of an optimal work product. Computerized information processing provides the decision makers with topical information related to their respective responsibilities. The mining department of the Hambach opencast mine is the first user of the PERMAD system. Due to the favorable evaluation it has been decided to introduce PERMAD in three other mines in the course of 1992/93.

Jan 1, 1992

By Wayne J. Nordstrom, Dennis L. Murr, James E. Wennen

National Steel Pellet Company (NSPC) conducted pilot scale testing and computer simulation studies which indicates that the capacity of the secondary grinding mill could be increased and that concentrate grade improvement could be expected with improved classification in the grinding circuit. Based on these studies, a decision was made to modify one secondary ball mill line at NSPC to include both cyclone and screen classification with magnetic separation applied to the circulating load. This paper will briefly discuss the studies leading to the decision to modify the circuit, the design of the modified circuit and the initial start-up and operating experience.

Jan 1, 1997

By James B. Loftis

The importance of increasing the world's mineral production to help solve our food and energy problems has been widely discussed. Improved surface mining methods will be needed to meet these needs. This paper reviews the modern horizontal drilling and blasting methods which can increase the productivity and lower the costs of I surface mining. A substantial decrease in the number of blast holes required, total footage of blast hole required and amount of explosive used has been realized by many mining companies using this method. Applications of this method are presently in large coal surface mines. However, similar gains are possible and probable in open pit mining of copper and iron.

Jan 1, 1975

By A. S. C. Owili-eger

An efficient state-of-the-art dynamic model to simulate and predict the rate of water production in longwall coal mining operations was developed as a tool for mine planning purposes. The model can also provide an estimate of any potential resultant hydrogeological impacts of an operation via an array of element-specific single-valued parameters referred to as the field rating indices. The computational procedure was designed to fully exploit the benefits of hydrogeotechnology and utilize a combination of conceptual, physical, empirical, and numerical approaches to define, characterize, analyze, and evaluate flow con- trolling properties of fractured rock systems. The model presented here provides a dynamic prediction method for highly fractured flow; a practical tool in mine and water control planning; and a cost-effective means of assessing, based on the best available technology, the impacts of mining on the water resources within a mining environment to satisfy local and federal regulatory requirements. Unique features include consideration of laminar and non-darcian flow domains in double-porosity-pressure hydrogeological media.

Jan 1, 1987

By E. R. Spencer, E. R. Bauer, G. P. Cole

Overexposure to hazardous noise has been found in most mining sectors, with up to 100% of the surveyed workforce experiencing a noise dose that exceeds the U.S. Mine Safety and Health Administration (MSHA) permissible exposure level (PEL). As a result, miners show elevated rates of hearing impairment of 70-90% by retirement age. To help manage noise exposures, the U.S. National Institute for Occupational Safety and Health (NIOSH) developed the Determination of Sound Exposures (DOSES) software and implementation guide for use by mine management and safety personnel. This paper describes the development, functions and basic operation of the initial-release version of DOSES. A revised version is being developed to incorporate additional user-suggested functions, and its development and implementation to assess noise control solutions will be described in a future article. The software relies on a time-motion study that profiles the worker’s daily activities. Observations about the worker’s location and tasks or other activities are recorded along with the start and end time, to determine the duration of the tasks so they can later be matched up with the noise data. The software gives the user the option of assessing dose relative to the MSHA PEL, the action level or the NIOSH recommended exposure limit. The software generates a variety of interactive on-screen displays showing where, when and how the worker’s noise dose accumulated. It also can generate customizable printed reports. These outputs can be used to highlight the tasks, locations and times that are associated with the greatest amount of a worker’s noise exposure. DOSES simplifies and streamlines the record keeping and analysis associated with time-motion studies and worker noise exposures, so mine management can make engineering noise control or administrative control decisions to limit the noise overexposure of their workers.

Jan 1, 2011

By Gretchen K. Hoffman, George S. Austin

Soil amendments or soil conditioners generally carry the con- notation of being useful for problem soils or soils needing special treatments to produce maximum yields. Many different materials have been utilized, both inorganic and organic. Only the most commonly used and those that appear to have potential to become commonly used will be discussed. Soil productivity depends on many factors. Soil amendments mainly modify physical characteristics and microbial action, and/or change the pH of a soil, rather than directly supplying plant nutrients. They give soil the needed physical properties to allow plant growth, fight erosion, or save water. Some soil amendments provide nutrients in addition to altering the physical, biological, or chemical characteristics of soil. The term "soil amendment," as it is used by Soil Science Society of America, allows soil amendments to be materials other than those used primarily as fertilizers (Anon.,1987). Soil amendments as fertilizers of any type will not be considered here because this aspect is more relevant to the previous chapter entitled "Agricultural Materials: Fertilizers" in this volume. Several inorganic soil amendments have been used since the early 20th century to alter the character of soil: limestone, lime, and similar calcium-rich carbonates and oxides for acid soils, and calcium sulfate (gypsum) and native or uncombined sulfur for alkaline soils. The use of these amendments (limestone, lime, gypsum, and sulfur) or their equivalents has been studied and documented in many basic soils tests (McCaslin and Boyle, 1980). Perlite and vermiculite are considered in separate chapters and only a brief statement of their use as soil conditioners will be made in this chapter. Peat is the principal natural organic soil amendment, but manure, both as a fertilizer and soil conditioner, is used in every part of the world. In less-developed countries, manure is the primary soil fertilizerlconditioner. An organic-rich material designated as "humate" has been marketed as a soil amendment for many years and will be addressed in this paper. Other materials are discussed by the Soil Science Society of America in its Special Publication 7, "Soil Conditioners" (Stewart, 1975). They include bitumen emulsion, polyacrylamide, polyvinyl acetate, polyvinyl alcohol, bentonite, nonionic surfactants, and natural mulches. Zeolites can be added to the list of miscellaneous soil amendments (McCaslin and Boyle, 1980), as can calcium chloride (Pressler and Pelham, 1985), sulfuric acid, ferric and ferrous sulfate, aluminum sulfate, ammonium polysulfide, calcium polysulfide, and ammonium bisulfite (Stromberg and Tisdale, 1979). Sludge will not be considered as a soil amendment because it has properties more consistent with fertilizers. All these "other materials" account for a very small amount of the volume and value of soil amendments used and will be only briefly discussed.

Jan 1, 1994

By Dennis V. D’Andrea, Peter G. Chamberlain, James J. Olson, William C. Larson

Blasts designed for in situ copper leaching must produce adequate fragmentation and permeability for successful leaching. Copper recovery depends to a large extent on the particle size distribution created by the blast, the permeability in the blast- fractured zone, and the ability to maintain solution flow with a minimum amount of channeling. This paper presents the results of Bureau of Mines experiments where core drilling was used before and after blasting to establish the degree of fragmentation. Data are presented from tests at the Sierrita mine of Duval Corp., and also from tests at the Emerald Isle mine of El Paso Mining and Milling Co. Copper recovery is predicted from fragment size distribution data using a computer model. Data from several blasts are used to show how predicted copper recovery is related to powder factor.

Jan 1, 1977