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By Ing. E. h. Martin Herrenknecht

The paper will describe a number of developments and innovations now in use in microtunnelling machines. These include the use of fuzzy logic steering systems, the proven ability to successfully undertake complex curved microtunnel drives, the ability to complete ultra long drives using microtunnelling techniques, and machines with access to the face of the machine from inside the machine. The ability to tunnel in relatively hard rock utilizing a rock head with back loaded cutters changeable from inside the microtunnel machine and the ability to utilize microtunnel machines in multi modes, such as hard rock mode, “open” mode, EPB mode, and slurry mode with the same base machine again with access to the face of the machine will be described. In addition, the latest computer technology gives the operator “full visualization” of machine functions together with the ability to data log machine operating parameters. Reference will be made to a number of projects worldwide recently completed or under way where these innovations have successfully been utilized.

Jan 1, 1999

By B. Jensen, R. Davis, P. Golledge, A. D. S. Gillies, W. Urbanik Urbanik

A current program of research on the explosibility of coal dust/methane mixtures is described. During the study an explosion test chamber based on a novel design has been developed. This 20 litre open chamber uses a rotating drum concept for dust dispersion and infra-red sensors for dust concentration measurement. The chamber design allows different initiators to be tested while varying methane gas and coal dust concentrations. A new approach to the determination of coal dust concentration is included with a description of a dielectric dust probe. The measurement technique is based on the change in dielectric constant as the proportion of coal dust in air between probe capacitor plates increases or decreases. Characterization of coal dust samples is of vital importance. The particle size distribution, coal proximate analysis and elemental analysis were studied. Coal dust was sourced from airborne collected samples, settled dust from mine sources and seam channel samples crushed and sized. Explosibility test results indicate that a very low concentration of coal dust can form an explosible mixture when dispersed in methane concentration of just below five percent. With low temperature initiators, the coal dust lean limit concentration rises rapidly as the methane concentration is reduced. An accurate knowledge of the potential explosion hazards of coal dust and coal dust/methane mixture is necessary to establish safe operating conditions in underground mines. The research results outlined extend knowledge in this area.

Jan 1, 1989

By Byron V. Knelson

Although the concept of centrifugal recovery has been around in one form or another for many years, it has not been until recent times that it has become clearly understood and properly put into perspective. Simplistic in theory, it is when one begins to examine the variables involved that the true complexities of this matter begin to emerge. In creating an enhanced g force concentrator, there are many aspects both positive and negative that are encountered. Many conditions that are inherent to all conventional 1 g concentrators do not apply to centrifugal concentrators and therefore very few cm factors exist between them. In developing this technology, virtually all principles were proven by method of trial and error. Among the topics discussed are the effect of g force enhancement on particulate behavior with respect to size and shape, density, enrichment, fluidization, and the "teeter principle". In addition, we will discuss the physical effects of g force enhancement with respect to manufacturing in the areas of abrasion, bearings, and vibration. In discussing the recovery parameters of centrifugal concentrators we will draw direct comparisons to various other recovery methods, outlining the conditions most favorable to their application.

Jan 1, 1988

By K. H. McDaniel, K. G. Wallace

This paper describes the development of a Windows-based interactive mine ventilation simulation software program at the Waste Isolation Pilot Plant (WIPP). To enhance the operation of the underground ventilation system, Westinghouse Electric Corp. developed a program called WIPPVENT. While WIPPVENT includes most of the functions of the commercially available simulation program VNETPC from Mine Ven- tilation Services Inc. and uses the same subroutine to calculate airflow distributions, the user interface was completely rewritten as a Windows application with screen grap-hics. WIPPVENT is designed to interact with WIPP ventilation-monitoring systems through the sitewide central monitoring system. Data (e.g., air quantity and differential pressure) can be continuously collected from the underground ventilation remote-monitoring and control system and from the mine's weather stations (psychrometric data). Furthermore, WIPPVENT incorporates regulator characteristic curves specific to the site. The program utilizes this data to create and continuously update a real-time ventilation model. This paper discusses the design, the key features and the interactive capabilities of WIPPVENT.

Jan 1, 1998

By Michael J. Howes

The nature of business in a free enterprise system is to maximise the return on an investment i.e. to maximise the wealth of the shareholders. This is normally achieved within constraints dictated by many agencies, one of which is the health and welfare of the employees. In the mining industry considerable effort has been expended in improvements in this field, however, the major problem still confronting the practicing ventilation or environmental engineer is the determination of what standards he should design for, which satisfy both the economic and health requirement s. Normally the basic health requirements are satisfied by the minimum standards defined in regulations and codes of practice. These are, however, based on an acceptance of a certain risk or lower production potential. A prime function of the ventilation engineer is therefore to financially justify and implement improvements to both standards and systems. The main purpose of this paper is to examine the basis and techniques of providing this financial justification. Changes in existing methods to achieve the same standards but at lower costs are also covered.

Jan 1, 1980

By J. J. Kellar, W. M. Cross, J. D. Miller

Infrared spectroscopy has been one of the most useful experimental techniques for the analysis of surface reactions in flotation systems, including surface alteration and surfactant adsorption reactions. With the advent of Fourier transform infrared (FTIR) spectrometers, many low-energy throughput IR experimental techniques previously unused by flotation researchers have come into greater use. In particular, internal reflection spectroscopy (IRS) is the most often used technique for in-situ studies. To date, three IRS methods have been used for in-situ measurements. These techniques are evaluated for use in characterization of surface reactions in flotation systems. The method using mineral crystals as reactive internal reflection elements (IRE) is of particular interest because it allows surfactant adsorption densities to be calculated directly from in-situ spectral data in real time. Application of in-situ FTIR/IRS with reactive internal reflection elements will be demonstrated for collector adsorption reactions in each of the major flotation systems. The alumina (A1203)/sodium dodecylsulfate system is used as an example for insoluble oxide/silicate flotation, while the fluorite (CaF2)/oleate system serves as a paradigm for semisoluble salt flotation. For sulfide flotation, sphalerite (ZnS) is used as the reactive IRE with potassium amylxanthate and potassium ethylxanthate as collectors. In the case of soluble salt flotation, sylvite (KC1) is used as the IRE with n-octylamine as collector. Finally, the use of reactive IREs in the near-IR spectral region and in spectroelectrochemical research is discussed.

Jan 1, 1989

By P. Mousset-Jones, G. Danko

Rock thermophysical properties, i.e. heat conductivity and thermal diffusivity, were obtained for reference values at the Waldo Test Mine for mine fire simulation purposes. An in situ measurement method was chosen since it could include the effect of rock fractures. The REKA method (Rapid Evaluation of k and alpha) was used because it can measure conductivity (k) and diffusivity (alpha) simultaneously within an eight-hour measurement period. A total of six measurements were taken in three different holes, and at two different depths from the collar of the hole. Each measurement provided an averaged conductivity and diffusivity for a volume of rock of approximately one cubic meter. The boreholes were driven into the upper and lower limestone, two at right angles to and one parallel to, the stratification of the rock. Significant representative conductivity and diffusivity values were obtained for the whole mine by averaging the six measurement results. The thermal properties for the band of shale in between the two limestones were not measured in situ, but only in the laboratory. Problems were encountered in the evaluation because of unexpected heat conduction on one side of the symmetrically built probe. A modification was made to the previously developed evaluation method together with further testing and correction, before the final results were obtained. As expected, the in situ and lab- oratory measured values of k and alpha compared favorably, since the in situ rock was dry and relatively unstressed.

Jan 1, 1989

By Robert C. Cifelli

INTRODUCTION Background and Objectives Underground coal mining is a vital component of West Virginia's economy. However adverse environmental effects including ground subsidence and aquifer dewatering are often associated with such mining activities. Many families in northern West Virginia still rely on private water wells and springs for domestic water needs. In such areas where underground coal extraction and land subsidence have occurred, a disruption of the ground water flow system commonly exists with subsequent drainage of water to lower levels that may extent as deep as the mine workings; this causes loss of water supplies to landowners and represents a nuisance to mining companies 2 This report represents a summary of an M. S. thesis project in geology at West Virginia University by the senior author (3). The intent for this study was to document the effects of underground coal removal on ground water levels at selected mine sites in northern West Virginia, as observed from water wells, springs, and streams. This research should be useful to coal companies and regulatory agencies and aid in recommendations of future water well locations and specifications in areas of existing or proposed underground coal mines.

Jan 1, 1986

By C. J. Bise, D. A. Poukhovski

Hazard recognition and prevention of accidents are two components of the 30 CFR 48 training requirements, which are mandated for new miners and newly employed experienced miners. These components are also part of the annual refresher training course required of all miners. In these categories, instruction shall include the recognition and avoidance of hazards present in the mine and shall include a review of accidents and their causes. Unlike instruction preparation for fact-based material, program development for hazard recognition presents a particular challenge to safety-training specialists, because they are often limited in their ability to adequately gauge the level of awareness of the individual prior to training. Further, they must also assure that the training is relevant and presented in a thought-provoking manner. Computer-based instruction is particularly well suited for assisting trainers in developing hazard-recognition topics, because it can be used in pretraining and posttraining modes for assessment of training effectiveness, in addition to its use as a presentation tool. This article presents a recent approach, developed at The Pennsylvania State University, that applies the technology for the assessment and instruction of accident prevention through hazard recognition. The application is prepared for surface coal mines.

Jan 1, 1999

By S. K. Mishra, S. B. Kanungo, D. Biswal

Jigging of the -2.8 +0.7-mm size fraction of a friable, low-grade manganese ore sample from Andhra Pradesh increased the Mn content of a concentrate by 7% to 8%, with an average recovery of 57%. The jig concentrate was mixed with the unjigged -0.7-mm size fraction and ground to -150 µm. The sample was then subjected to wet high-intensity magnetic separation (WHIMS). The magnetic fraction thus obtained showed an increase in Mn content of 6%, but with an overall recovery of only 50%. The results of hydrocyclone classification of -150- µm ground ore indicated that the method is not capable of upgrading the manganese content, as both ferromanganese oxides and aluminosilicate gangue minerals constitute the fine size fraction. However, when the nonmagnetic fraction obtained from the WHIMS of -150- µm ore is subjected to hydrocyclone classification and the underflow obtained is subjected to WHIMS again, an overall recovery of about 50% to 52% is obtained with at least a 7% to 8% increase in the Mn content of the product. The phosphorus content in the product is not reduced by either of the two combinations of methods. The complex association of phosphorus with all the major phases in the ore has been clearly demonstrated from the linear correlation between the distribution ratios of major constituent phases and phosphorus.

Jan 1, 2000

By Daryl R. Tweeton

The Bureau of Mines has developed PC-based tomographic computer programs for geophysical applications, and is making them available to potential users as part of a Bureau plan to facilitate the transfer of technology to industry. These programs were initially developed for predicting and monitoring the flow pattern of leach solution during in situ mining. Seismic crosshole tomography has located fractured zones of low seismic velocity and saturated zones of high seismic velocit above the natural water table. The Bureau has applied tomography also to assessing high-wall blast damage, and examining the integrity of mine-related geological structures. The tomographic programs include the straight ray pro ram BOMTOM (Bureau of Mines Tomography? and the program BOMCRATR (Bureau of Mines Curved Ray Tomographic Reconstruction) that can be run with either curved or straight rays. Both programs provide optional mathematical constraints to help counteract the nonuniqueness of reconstructions that occurs with crosshole data. They are available from the Bureau free of charge. With typical data sets, they can be run on a 386 microcomputer with 640 Kb RAM. BOMTOM was described in the Bureau Report of Investigations 9159, so this report emphasizes BOMCRATR. Curved and straight ray reconstructions using seismic field data collected while simulating injection of leach solution were compared. The curved and straight ray tomograms were quite similar even with velocity variations of more than 50 percent.

Jan 1, 1992

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 K. H. McDaniel

This paper describes the development of a Windows-based interactive mine ventilation simulation software program at the Waste Isolation Pilot Plant (WIPP). To enhance the operation of the underground ventilation system, Westinghouse Electric Corp. developed a program called WIPPVENT. While WIPPVENT includes most of the functions of the commercially available simulation program VNETPC from Mine Ventilation Services Inc. and uses the same subroutine to calculate airflow distributions, the user interface was completely rewritten as a Windows application with screen graphics. WIPPVENT is designed to interact with WIPP ventilation-monitoring systems through the sitewide central monitoring system. Data (e.g., air quantity and differential pressure) can be continuously collected from the underground ventilation remote-monitoring and control system and from the mine's weather stations (psychrometric data). Furthermore, WIPPVENT incorporates regulator characteristic curves specific to the site. The program utilizes this data to create and continuously update a real-time ventilation model. This paper discusses the design, the key features and the interactive capabilities of WIPPVENT.

Jan 1, 1997

By Vathsala Rajagopal, lwao lwasaki

The grinding media materials for the mining industry require corrosion and abrasion resistance properties not only to minimize the wear but also to improve the flotation recoveries of sulfide minerals. The media wear mechanisms and the factors influencing the grinding ball wear during grinding are discussed with respect to abrasion, corrosion and impact wear of grinding media materials. Interactions between the grinding media and sulfide minerals in a ball mill adversely affect the floatabilities of the ground minerals. The possible galvanic interactions between grinding medium-mineral and their effects on the flotation responses of sulfides are also reviewed. The selection criteria for alloy composition that reduces the overall wear along with adverse effects on flotation are brought out.

Jan 1, 1992

By T. R. Ellis

A number of important international events took place in 2001 in the development and evolution of mineral valuation standards internationally. In Canada, the CIMVal Committee released a draft discussion paper for public and industry comment on principles to guide the development of the planned Canadian mineral-property valuation standard. The International Accounting Standards Board (IASB) received comments on its Extractive Industries Issues Paper. IASB will decide whether the financial statements of public mining and petroleum companies will be allowed to provide the value of mineral and petroleum assets on a current value basis instead of an historic cost basis. The author led the Extractive Industries Task Force of the International Valuation Standards Committee (IVSC) in developing its submission to IASB. IVSC intends to develop an extractive-industries valuation section for its International Valuation Standards, which could support the planned IASB standard. In Australia, AusIMM has carried out an in-depth review of its highly regarded VALMIN Code. The AusIMM's MICA subdivision organized the VALMIN `01 Conference in Sydney, Australia, with a range of international and current issues papers published in the VALMIN '01 book. Considerable support for the IVSC initiative was evident at this conference. The results of the review of the extractive industries submissions to the IASB were expected to be released in early 2002. The CMMI Congress in Cairns, Australia in May 2002 is likely to prove to be an important forum for continued discussion of the development and implementation of international standards and qualifications for mineral valuation. The outcomes and implications of these events are discussed.

Jan 1, 2003

By Paul B. Queneau, Barry J. Hansen, D. Erik Spiller

Most lead and zinc secondaries are recycled pyrometallurgically. However, many problems encountered in secondary smelters have been solved by addition of physical concentration and/or hydrometallurgical processing steps, with resulting important environmental benefits. U.S. secondary lead and zinc operations are described, covering conventional smelters, EAF-dust treaters, and zinc sulfate/fertilizer producers, including plant capacities, technologies, and outputs. During the past two decades, remarkable advances have been achieved by recycling spent lead-acid battery components. Interaction between primary and secondary zinc producers, the fertilizer industry, and the zinc chemical industry has substantially decreased waste generation.

Jan 1, 1993

By P. Diehl

The increasing public interest in a useful framework for an assessment and classification of mineral resources (1) is documented by the recently published international classification scheme of the United Nations (1979) and the revision of the classification system of USBM/USGS (2) (1980). Moreover, various classification systems are currently discussed by the mining industry. In spite of major improvements in respect of the concepts, definitions, and taxonomy of ore classification, it has been recognized that the recent practice to classify mineral resources does not create truly reproductible results, i.e. an assessment to the various categories which is free from personal bias or corporate interests. Following are geostatistical methods proposed for a standardization and quantification of various terms in ore classification. After critical review of present practices, we will establish a precise link between the classical terms such as "measured", "indicated", and "inferred" reserves and the geostatistical concept of estimation errors. Moreover, we will demonstrate, how the basic criteria of economic feasibility, geologic assurance and recovery can be taken into account by geostatistics. A specific algorithm will be proposed to block out and to classify reserves according to the degree of geologic assurance. . We will also show computerized methods which perform complete classification procedures, and will also exemplify them with typical case studies.

Jan 1, 1982

By J. D. Miller

Fluid flow phenomena and therefore the flotation efficiency of air-sparged hydrocyclone (ASH) flotation are strongly dependent on operating and design variables such as air and slurry flow rates, underflow and overflow opening areas, percent solids of the feed, reagent levels, particle size and ASH length. Time-averaged multiphase flow characteristics, as determined by X-ray CT (described in a previous publication), are used to understand and explain the steady-state ASH flotation of quartz. A detailed parametric study of quartz flotation by a nominal 2in. diam. air-sparged hydrocyclone (ASH-2C) revealed the influence of these variables on the flotation response, which is discussed in terms of the multiphase flow characteristics. Thus, a phenomenological description of quartz flotation has been established to assist in the further development and utilization of the ASH technology.

Jan 1, 1996

By Vernon R. Degner

The past two decades has seen the application of the mechanical flotation machine, originally developed primarily for metal1iferous ore beneficiation, increasingly applied to cleaning coal in the 28x0 T. Mesh size range. Internal cell hydrodynamic studies of mechanical flotation machines of all sizes, as well as computer aided modeling studies of flotation kinetics has, within the last five years, established a basis for optimizing coal flotation circuit design and machine operation, and has a1 so pointed a way toward improvements in mechanical flotation machine design for the future. Consideration of the trend toward increased fines produced by current mining techniques, as well as the environmental need for a progressively cleaner product, lends support to basing the design of the mechanical coal flotation machine of the future on finer feed; below 100 microns in size. Future types of mechanical flotation machines, which may satisfy the fine coal cleaning requirements for a significant improvement in product grade while maintaining the combustible recovery levels of current technology, are discussed.

Jan 1, 1988

By Kenneth S. Johnson

Oklahoma is a region of complex geology where a mobile belt of Paleozoic geosynclines and uplifts on the south abuts against the margin of the North American craton to the north. The state contains many classic areas where fundamental concepts of sedimentation, stratigraphy, structural geology, historical geology, mineral investigation, and petroleum exploration have been formulated through the years. In the southern Oklahoma mountain belts, there are exposed a great variety of igneous and sedimentary rock units seen at few other places in the Midcontinent area. Major geologic provinces of Oklahoma (Fig. 1) include: (1) the cratonic and relatively stable northern shelf areas, including the Ozark uplift; (2) the Ouachita geosyncline (now the Ouachita Mountain belt) and associated Arkoma basin in the southeast; and (3) the southern Oklahoma aulacogen (geosyncline), comprising the area of Anadarko, Ardmore, Marietta, and Hollis basins, as well as the Arbuckle and Wichita Mountain uplifts. The three principal fold belts, the Ouachitas, Arbuckles, and Wichitas, all originated from a series of Pennsylvanian orogenies (about 300 million years ago) in the two Paleozoic geosynclines.

Jan 1, 1999