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By D. A. Swanson

Predicting when and at what rate seepage will occur from waste-rock facilities is becoming an integral part of permitting and closure at mines situated in dry climates. Such predictions require development of a conceptual framework that accurately describes how water will percolate through a waste-rock facility. Also needed is a detailed hydrological characterization of the waste-rock facility, including measurement of the hydraulic properties of the waste rock and any potential cover materials. This paper presents a conceptual framework describing unsaturated water flow in a waste-rock facility and describes methods for characterizing the hydrology of a waste-rock facility in a dry climate. The methods are designed to collect site-specific data to support accurate and defensible predictions of long-term seepage rates.

Jan 1, 1998

By M. Z. Emad, M. U. Khan

"Coal mines opting for longwall mining or its variations rely on the main and tail gates for production. Stability of these entries or crosscuts is crucial in coal mining operations. Roof or strata failure can be fatal, may lead to property loss and delay in production. Failure of the gates depends upon many factors including the mining method, panel dimensions, pillar width, mine depth, caving rate, dimensions of gates and roof strength properties. In Pakistan coal is mined through a variation of longwall mining method with almost no mechanization while using timber as a primary support. Timber support as chock is very useful in coal mines especially in overhanging face. Similarly gate entries and coal faces are supported by chock supports throughout their length. In this paper the stability of the longwall gate is assessed for a typical coal mine in Pakistan by using finite element code. Numerical modelling considerations for gate entries are discussed. A model parametric study is performed for key factors. The results showed that the existing mining practice is not suitable and there is a need to review the mining approach. INTRODUCTION Main and tail gate entries leading to longwall mining panel play a crucial role in production cycle. Failure of any of these may lead to loss of life, property and production delays. The stability of gate entries depends primarily on the nature of loading and stresses incurred. It is relatively easier to assess the ground response to production for common longwall mining panel. In thin-seam coal mines the gate entries are generally supported throughout their length by timber made chock supports. The tailgates receive huge deformations and stresses during the mining and backfilling cycle. The chock supports are required to take care of rock falls leading to blockage of entries causing production delays and loss of capital. A number of supports are available for supporting the gate entries (Hoek and Brown 1980; Brady and Brown 1985). The support system can be selected based on load-deformation characteristics including the yielding behavior, pre- and post-yielding behavior (Barczak, 2003). The principal of support selection is that the support characteristics must match the ground response in order to maintain the gate entries (Mucho, et al., 1999). It has been observed that thin-seam mining (<1 m) is very challenging and it is necessary to develop an understanding of ground mechanics before the selection of an efficient support system Dolinar (2003). The chock supports have been tested for load-deformation characteristics in the laboratory (Barczak 2003). But the ground and support interaction, response and loads must be assessed for individual site. This can be accomplished by in-situ testing and observations at few locations. The generated data is generally insufficient for complete understanding. Numerical models can combine the data generated in the laboratory and on-site to fulfill the requirements."

Jan 1, 2017

By Michael T. Ballard

The key to productive computer usage is system software integration with full compatibility among individual components. The majority of software developers in our industry are still in the process of perfecting individual components. As a result, exchange and validation of data between disciplines becomes an arduous process. We at Morrison Knudsen Engineers, Inc. (MKE) have integrated an entire system, allowing exploration, geology, modeling, mine planning, and operation modules to work as a single, complete system with direct exchange and validation of data. The importance of integration to both developers and users of today&apos;s mining soft- ware is becoming increasingly apparent as we, an industry, move toward growth and enhancement of the technology of ore reserve acquisition, evaluation, and management. It is also important to understand the present state of integration and where it is leading US. Not long ago, another industry passed through the same stages we are now setting up for the mining industry. The stereo industry began with a few individual components, the record player, tape recorder, and radio. People were able to play records, listen to the radio and record conversations and music only through microphones on their tape recorders. Soon, one enterprising individual discovered he could tape sound directly from the radio or record player by capturing audio output from the speaker wires. Interfaces and patch cords were developed, providing a means to transfer audio information between components with not only little loss of sound quality, but also the elimination of back- ground noise. The industry took another step forward with the introduction of "integrated" stereo, where the components were packaged in one cabinet with shared resources. This reduced overall cost which paved the way for better quality. Today&apos;s stereos are now so well integrated that many of the components share data and resources from the same manufacturer, designed to work together for almost perfect data transfer between any of the components. The result is better sound, convenience, and reduced cost. This is the ultimate goal for integration. Any system development passes through these same steps on the road to total interaction. Initially, the components are designed, tested, and marketed individually, often by separate companies. As the users become familiar with the components, the need arises for an automatic interface between the components. This is necessary to cut down on error during data transfer and to eliminate the redundant work required to enter results from one component into the next component in the system. As a result, interfaces must then be developed to aid in this data transfer. After data transfer is accomplished, the next step is resource sharing. Resource sharing is careful design and engineering by either cooperative, individual manufacturers or one firm taking on the task to produce a single package product. Design and resource sharing leads to lower overall cost, while still providing component capability with options to grow as the user grows. The mining software industry has been working to develop some very high quality component software and has indeed accomplished this task in every aspect of the mining industry. However, realizing the importance of integration, some companies with limited individual resources have started working together to interface their individual components. Other firms have undertaken the project of developing complete, integrated systems.

Jan 1, 1987

By Arthur A. Schweizer

A method to improve the quality of Magmnt zinc concentrates to become acceptable feed to an electrolytic zinc refinery. The magnesia content of zinc concentrates produced was too high due to particle locking with the sphalerite in coarse fractions. Regrinding of the concentrates to a very fine particle size and then refloating the sphalerite was chosen to eliminate a sufficient amount of the magnesia to make the concentrates acceptable.

Jan 1, 1981

By J. Stoll

In May 1998, Hanson Aggregates Midwest, as an outcome of mine planning, offered a 10-acre tract of land containing the famed fossil-bearing Silica formation, to the City of Sylvania, OH. in the form of a 99-year lease agreement. The Olander Park System, and Ohio code park operating within Sylvania Township, was then approved by Hanson and the City to manage and fund the park. All parties signed the lease in August of 1999. In November 2001, local residents voted to fund the park by a margin of 2 to 1. The park will consist of a shallow (approx. 20 ft.) former cement production quarry that is 700 ft. long by 300 ft. wide. Hanson’s motivation and vision for the park was fivefold: 1) the site was located away from long-term reserve access; 2) it would serve nicely as buffer property for the active quarry; 3) it had become an area of illegal dumping by locals in the past; 4) trespassing and safety issues would be limited by allowing supervised usage; and 5) the shallow outcropping contains the world famous, fossil-bearing Silica shale. Hanson will supply shale to the park perpetually via stripping activities in the process of uncovering quality construction aggregate limestone and dolomite reserves. Thousands of enthusiastic fossil hunters have already combed throughout the shale in their quest for “treasures”. The park’s master plan also features nature trails, picnic areas, a fossil-themed play area, amphitheater, visitor’s center and gift shop. Given the natural and people resources that Sylvania Fossil Park will have to offer, Hanson is confident that it will become the premier invertebrate fossil hunting site in the United States. It will also remain a solid community relations vehicle for years to come.

Jan 1, 2003

By T. F. Torries

Market data commonly perceived as being useful to industry for decision making include prices, production and trade quantities, production and transportation costs, stocks, customer&apos;s needs, and competitor&apos;s qualifications. Costs and factors affecting costs are particularly important in determining competitive positions and possible future prices. These costs include relative cost of production as well as cost experienced by the buyer in making the final product. Care must be taken to calculate costs in a consistent manner to achieve meaningful analyses.

Jan 1, 1987

By Robert L. Bates

The field of industrial minerals and rocks includes such a wide diversity of materials and occurrences that communication is essential to foster a sense of "belonging? among geologists and other professionals. Besides, exchange of ideas and information is essential in meeting the needs of an ever-expanding world economy. A survey of the field shows to what an extent such communication--especially in the form of conferences and their proceedings--has increased during the past 25 years.

Jan 1, 1995

By C. G. Bock

Geologic profiles constructed from exploratory drill holes gave basic geologic information for bidding on 4913 ft. of twin rock tunnels under the Potomac River. To provide additional geologic information for construction, tunnel faces and shafts were mapped throughout excavation. This information was plotted in plan and section so that geologic structure could be projected ahead and prediction of conditions could be made. In structurally complex areas, 3-D models were made and used to show the geologic structure. Core from exploratory drill holes was relogged and structure oriented with that found in the tunnels to make the ultimate use of the core and refine the geologic picture. As excavation proceeded, geologic mapping showed that the projection-prediction approach was useful and essentially correct.

Jan 1, 1974

By Paul L. Russell, R. G. K. Morrison

9.1-CLASSIFICATION OF MINERAL DEPOSITS AND ROCK MATERIALS After a mineral deposit has been discovered, delineated and evaluated, the next step is to select a mining method that is physically, economically and environ- mentally adaptable to recovering the mineral from the deposit. The term "mineral deposit" is used to denote a concentration of mineral (including rock and coal). Even where there is considerable past experience available, many of the critical design criteria must be determined utilizing only information obtained from an examination of exploratory drill core specimens. The factors that affect this selection are as follows: (1) the spatial characteristics of the deposit (size, shape, attitude and depth); (2) the physical (or mechanical) properties of the mineral deposit and surrounding rock; (3) ground water and hydraulic conditions; (4) economic factors, including grade of the ore. comparative mining costs and desired production rates; and (5) environmental factors, such as the preservation of the surface overlying the mine, and the prevention of air and water pollutants. Of these factors, the spatial characteristics of the deposit and the physical (or mechanical) properties of the mineral and surrounding rock limit the methods that can be employed to mine it. Six types of mineral deposits are recognized, as follows: 1. Massive-A deposit of considerable lateral and vertical extent in which mineralization (or ore) is relatively uniformly distributed. Disseminated copper ores are typical deposits. Dome salt also is included in this classification. 2. Bedded or Tabular-A mineral deposit that parallels the stratification, most often in sedimentary rock, usually laterally extensive, and of limited thickness. Most coal measures and some evaporite mineral deposits (e.g., potash) fall in this class. 3. Narrow Vein-A zone or belt of mineralization (ore) typically long, narrow (less than 10 ft), often dipping steeply, and usually lying within boundaries separating it from neigh- boring rock. Many gold and other metallic minerals occur in narrow veins. 4. Wide Vein-As defined under narrow vein except that the vein thickness is greater than 10 ft. 5. Lentictclar or Pocket-An isolated ore body, or an enrichment of limited vertical and horizontal extent in a massive, bedded or vein deposit. Lead, zinc and iron ores often occur in this type of deposit. 6. Placer-A surface or near-surface deposit, usually tabular and may be of consider- able areal extent, containing mineral particles (e.g., gold, platinum) in detritus (e.g., sand, gravel). The rock materials associated with mineral deposits are classified as follows: 1. Detritus-Sediments and other accumulations of solid particles produced by the mechanical and/or chemical disintegration of rocks, and usually having a low cohesive strength and very low compressive strength (e.g.. soil, sand, gravel, alluvium, playa). 2. Jointed and Fractured-Unbonded-A rock mass, often occurring on or near the surface or in fault zones, in which the joints or fractures contain alteration or decomposition

Jan 1, 1973

By S. Vijayan

Despite the limited demand for rare-earth elements, as well as yttrium and scandium, in conventional applications, the emergence of ne~ high-technology applications such as supermagnets, lasers and superconductors is expected to result in significant demand for some of these elements. This paper examines the anticipated applications and demands for rare-earth elements over the next decade and their implications on the utilization of available resources. Process methods for the recovery of rare-earth elements from conventional and unconventional resources are reviewed in the context of their growing demand. Challenges facing the industries in meeting this opportunity are also discussed.

Jan 1, 1988

By B. K. Belle

The use of diesel engine locomotives in South African mines can be traced to Van Dyk Consolidated Mines Ltd on the Witwatersrand gold mines in 1928 as a replacement for battery locomotives. The advantages and disadvantages were recognized in those days, and surprisingly, there are no significant additions to this list, but only refinements. In the absence of any Occupational Exposure Limit (OEL) for Diesel Particulate Matter (DPM) in SA, the Mine Safety and Health Administration (USA) rule is currently being used as a benchmark for the ventilation engineering designs. This paper discusses the ongoing SA journey of measurement and limitations of exposure data for ventilation planning and regulatory purposes. The currently accepted DPM limits are based upon the belief that they are economically and technically feasible for the mines to reach and are not necessarily health based. For SA underground platinum mines, a median TC/EC ratio of 1.8 with a range of 1.2 to 5.8 was observed. For SA coal mines, a median TC/EC ratio of 1.44 with a range of 1.25 to 2.13 was observed. While it is common practice in the USA to use the ratio of TC/EC for metal mines to be 1.3, the ratio found in local platinum mines is 2.2 and for coal mines, the ratio was 1.53 which is lower than Australian studies, i.e., 1.96. It has been shown that a need for critical analysis of TC/EC ratios exists, and possible reasons for variance must be understood before stringent adoption of overseas recommended limits for DPM. It is hoped that the findings from this paper would provide input to scientific approaches in developing appropriate conversion factors, limits for DPM and also in ensuring appropriate error factors (currently 1.14 for TC and 1.2 for EC) for compliance determination.

Jan 1, 2009

By Ian Farmer, Nigel Glossop, Philip Garritty

Performance of tunnel boring machines - usually expressed in terms of penetration per revolution - is determined by relations between machine thrust and torque, head diameter and rock strength. It can be shown that for a given machine power and head diameter there is only one rock strength at which the machine performs optimally. In weaker rocks the available torque limits performance and in stronger rocks, the available thrust. Performance data shows that, historically, machines have been designed to cut weaker rocks. Optimization of thrust is required to improve performance in stronger rocks.

Jan 1, 1987

By E. Iasillo, R. R. Carneiro

Independent of the method chosen to forecast production, an accurate method to project metal extraction is needed in order to accommodate leach cycles that exceed leach data on hand and thus be able to accurately forecast production. Metal extraction data must be developed for each ore type identified in the deposit in order to apply the correct rate of leaching when a specific ore is being treated. Curve fitting is used to model the rate of disengagement of metal into the pregnant solution. This paper provides a description of a curve fitting algorithm developed by Mr. John T. Bartlett, inventor of the METSIM™ process simulation program. A methodology is provided by which the metallurgical data developed is evaluated to determine if accurate projections may be made from the data. A criteria has been developed to help determine when a column experiment may be terminated.

Jan 1, 2001

By J. B. Platt

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

Feb 24, 1997

By R. M. Quinlan

The coal industry in the United States has undergone significant economic changes during the past six years. The price of coal remained relatively constant from 1950 to 1969 (See Figures 1 and 2). Steam coal prices tripled and metallurgical coal prices doubled from 1969 to 1974. This price structure has created a new economic environment for coal preparation. Contributing factors to these price trends include: ? Coal Mine Health and Safety Act of 1969 ? Mid-East oil embargo of 1973 ? United Mine Workers of America contract agreements ? Productivity decrease (tons per man-day basis) ? Environmental Protection Agency regulations The increased value of coal justifies additional capital investment in cleaning facilities to optimize yield. Current trends include recovery of existing slurry ponds and recleaning of refuse. Coal preparation plant product yield and quality must be evaluated in terms of the amount of capital expended and cost of operation. Therefore, it is advantageous to optimize the plant product based on clean coal selling price and rate of return on investment.

Jan 1, 1976

By James F. Albus, Vincent C. Grimshaw

High pressure fluid energy grinding, or jet milling, is a versatile method of continuously fracturing solids into fine particles to gain substantial increases in exposed surface area Applications in industrial minerals grinding include calcium carbonate, talc, barytes, mica, diatomaceous earth, bauxite, rutile, coal, kaolin, sepiolite, diamonds, etc The basic principles can be extended to provide continuous drying and delivery of discrete par¬ticles from a wet process slurry The main design and operational features of jet mills and dryers are described, relating energy consumption for both air and steam milling and hot air drying techniques Mean particle sizes in the order of 1 micron are achievable from pre-milled feeds, or maintained from similar slurries in the drying mode Aspects of feed preparation and multi-stage processing are discussed

Jan 1, 1983

By Z. Scopa, E. Tarshizi, R. Setterlind, L. Frost, R. Livernois

"THE MINES OF THE FUTURE The mines of the future present a host of challenges, which may appear exciting or daunting depending on one’s perspective. Whether some sectors of the public recognize it or not, the demand for raw resources is not going away any time soon. In fact, it is rising as global population grows, urbanizes and attempts to steadily increase quality of life. Yes, at the same time that much of the highly developed world is calling for greener goods, reduced consumption, and cleaner production, in other areas there are cries for clean water and sanitation, consistent energy supply, access to health care and education, personal security, and support for basic human rights. The balancing act for sustainable development of our global society is indeed precarious, and the mining community is necessarily a key player. Fortunately, many industry members have accepted this role and the responsibility to provide leadership and a solid foundation for progress. Looking ahead, we need new generations of leaders, many of whom will be mine engineers, which are ready to tackle all sorts of complex problems. There are tremendous needs just for technological innovations. Increasingly tough deposits will require that we continue to expand scale toward “super” pits and “deep” underground mining fully develop unconventional recovery techniques like in-situ leaching and gasification or deep-sea extraction, and seriously consider off-earth endeavors. Such work will take entirely autonomous equipment; novel separations, processing and recycling methods; and systems that can withstand extreme physical conditions – just to name a few. It will also take a level of systems integration never-before seen in our field, complete with big data issues, sophisticated analytics and modeling efforts, and cyber-security challenges. Moreover, increasingly complex environmental problems will require creative solutions. Addressing issues like pollution control across multiple media, emerging contaminants, optimal management of wastes, selective mining, and shared use of resources between mine operations and surrounding communities and ecosystems are among top priorities. Really, a complete paradigm shift must occur, such that our focus is on overall improvement of environmental conditions, rather than minimization of impacts. A similar shift will be required in the social realm. How can we make miners safer and healthier on-site and off? How can we contribute to communities such that they are better off, now and long-term, for having a mine next door? How can we help transform artisanal mining practices to also contribute to sustainable development? How can our work be a factor in increasing economic and political stability? How can we improve the public understanding of raw resources and the need for mining enterprises?"

Jan 1, 2017

By M. Ge

Pattison Mine is a small sandstone mine located in Iowa. The sandstones produced by the mine are not common construction and aggregate materials. The stones are used to produce a special type of sand for hydraulic fracturing, a critical technique for recovering tight gas and shale gas. These sandstones are very different from the minerals and rocks which have been studied extensively in mining. On the one hand, they are brittle as characterized by an unusually high friction angle, up to 69°, and steeply curved failure envelopes. On the other hand, they are friable, possessing extremely low, and in most cases zero cohesion. The scarcity of the ground control techniques for this particular mining environment has created many difficulties for the mine operators. In order to resolve these problems, a research program was set up by the mine and Missouri University of Science and Technology. This paper discusses the preliminary results of this investigation.

Jan 1, 2012

By Allen G. Taylor

High-value materials, such as gold, platinum and other precious metals, are subject to loss through unauthorized removal from mines, smelters, refiners and other places where such materials are processed. A study by Gastrow (2001) determined that between 1994 and 1998 an average of 603 kg/a (1,330 lb/year) of gold was stolen from South African mines and subsequently recovered. This does not include the gold that was stolen but not recovered. At 2011 prices, 603 kg/a (1,330 lb/year) of gold would be worth approximately $33 million. Mine security personnel believe that the unrecovered stolen gold far exceeds what is recovered (Gastrow 2001). Traditionally, metal detectors have been used to screen personnel leaving secure areas to discourage such unauthorized removal. However, with the current near-record prices of gold, platinum and other precious metals, it has become worthwhile for people exiting a facility to walk out with quantities of product that are too small for ordinary metal detectors to register, resulting in substantial financial losses.

Jan 1, 2012

By H. F. Broicher

Introduction In April 1998, AIS Sommer GmbH of Germany delivered the first laser-induced fluorescence (LIF) analyzer to the mining industry. LKAB&apos;s Kiruna iron ore mine in Sweden shared the costs and the risk of building the prototype. This marks the beginning of LIF analysis as a technique for quality control in mining and mineral processing. Photoluminescence analysis is well established. In most laboratories, fluorescence spectrometers are standard equipment for quality or pollution control. LIF is being used in several applications, including combustion studies and particle image velocimetry. However, it has mostly been used in laboratory environments. The availability of rugged lasers for industrial use brings this powerful tool to the forefront of production, even in the rough conditions found in mining and minerals processing. Laser-induced fluorescence Basics. Fluorescence of naturally occurring minerals has fascinated man since scientific investigation of this phenomenon commenced about 200 years ago. However, importance in industrial application and peripheral activities. Hand sorting of ore under ultraviolet (UV) lamps is seen as an archaic method. Long gone are the days when geologists set out at night with UV hand lamps to find valuable ore deposits, especially those of tungsten. Today, fluorescent minerals are considered collectors&apos; items and museum exhibits. In the late 1960s (Hemphill, 1968) and during the 1970s, attempts to use lasers for excitation of fluorescence in minerals led to the development of an airborne fluorosensor (Seigel and Robbins, 1980). However, this prospecting technology did not gain industry acceptance and vanished from the market. During the past seven years, ongoing research of the LIF of minerals resulted in new findings that give good reason to revive the interest in fluorescence and its use in the mineral industries (Broicher and Zydek, 1995; Broicher, 1998). Fluorescence is defined as the short-lived form of photoluminescence, in which matter emits visible radiation during and after irradiation with light – the fluorescence generally being of a longer wavelength than the irradiation. Fluorescence of matter is described by: • the absorption spectrum, • the emission spectrum, • the decay curve and • the quantum efficiency. The absorption spectrum shows the fluorescence intensity in a fixed spectral band as a function of the excitation wavelength, while the emission spectrum shows the fluorescence intensity at varying emission wave- lengths for a fixed excitation wavelength (Fig. 1). The decay curves describe the exponential decrease of the fluorescence intensity with time. The quantum efficiency is the ratio of irradiating energy to emitted energy. Re- cent research has found that: the quantum efficiency of minerals can be measured and evaluated,

Jan 1, 2000