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By Bo Hyun Kim, Mark K. Larson

Although techniques and practices of mining are highly advanced, coal pillar bursts or bumps continue to occur. Many uncertainties remain because of the highly anisotropic characteristics of coal seams that are associated with geologic structure and the mining-induced spatial redistribution of stress in coal pillars. Thus, to prevent fatalities in underground coal mining, continuous efforts are required to better understand the catastrophic failure mechanisms in coal mines. In this study, 3DEC modeling in conjunction with the Discrete Fracture Networks (DFNs) technique was performed to better understand the true anisotropic behavior of the specimens acquired from a bump-prone underground coal mine. The spatial characteristics of the dis- continuities (i.e., cleats and bedding planes) as input data for the 3DEC model are estimated based on the results of the laboratory tests and field observations. The DFNs explicitly generated the coal seam that was poorly or well cleated, indicating the different spacing between cleat apertures using the probability distribution functions for fracture density (or frequency) and size. The heterogeneity of the engineering properties (i.e., cohesion and tensile strength) are also considered by Monte Carlo simulations. Simulation results of laboratory tests using the 3DEC model and DFNs technique agreed well with the results of the laboratory tests. These calibrated results can be used as we seek to evaluate bump risk by modeling at field scale.

Jun 25, 2024

By Carrie Smith

In 1972, in Denver, CO, five women with a shared goal joined forces to create the first formal space for women in the mining industry: Women in Mining USA (WIM USA). When the organization first took shape, few could have predicted that a small gathering of women would grow into one of the most influential organizations that would advocate for inclusion in the industry. Now, more than 50 years later, the group remains a vital network for professionals across the United States with a diverse array of membership and chapters.

Jan 1, 2026

By N. W. Stump

New developments in on-stream analysis using immersed radioisotope gauges including results from plant installations are described. The control of grinding and flotation using a small digital computer has been complemented by this development. A control scheme for grinding which is based on maximum throughput at constant product size and preliminary work in flotation control are also outlined.

Jan 1, 1974

By R. D. Coursen

Tin has been one of the very few commodities which has been covered by an international commodity agreement. It is the only metal so covered. The reason behind tin's prediliction for an agreement has been the inconsistency of the price pattern for tin during the entire 20th century. It is not surprising in view - of the wide and wild fluctuations in its price that tin has been called the Cinderella metal. An examination, for example, of prices in 1977 alone attests to the erratic behavior of the tin markets. The high was recorded on October 27 at M$1,895 per picul and the low on January 3 at M$l,314 3/8, on the Penang market, a spread in Malaysian dollars of $581 for a picul weighing 133 1/3 pounds. The first steps in international cooperation on tin were taken after the price bonanza of the First World War. Despite a lack of increased consumption, and in spite of the fact there was no shortage of mining production during the war, prices boomed. Shipping shortages and thinning stocks brought about a situation where in the U.S., industrial stocks were only 1/6 of what they had been in 1914. The boom busted early. In 1921 the tinplate industry of the world had cut its output in half and total world consumption of tin fell by 1/3. Tin producers became so concerned that they created what was called the Bandoeng Pool. It accumulated stocks held by countries now known as Indonesia and Malaysia, amounting to 28 percent of the combined production of the two countries and about 15 percent of the total world for 1921. The pool holdings were shortly exhausted and thereafter in the years 1924 to 1928, general boom conditions existed for tin.

Jan 1, 1978

By R. E. Hucko

The goal of the U.S. Department of Energy (DOE) coal preparation R&D program is to develop technology to reduce the ash and sulfur contents of United States coals to levels such that the resultant product can be formulated into a high- quality solid or slurry fuel that could replace oil or natural gas in both new and retrofit applications. The Coal Preparation program is implemented by the Pittsburgh Energy Technology Center (PETC) and is conducted both in-house and by a cross section of industrial organizations, universities, and national laboratories.

Jan 1, 1986

By K. C. Kocsis

Underground ventilation systems, which require electricity to operate the fans and fossil fuel for heating in winter, can account for a significant portion of the energy consumption of mines. Recent studies have shown that the ventilation system in deep and highly mechanized metal mines could be responsible for 40 to 60 percent of their overall energy consumption. Presently, underground ventilation systems are designed for peak air volume requirements, which usually occur well into a future stage of the mines’ operating life. As a result, during their early operating stages, the intake air volume of the mines could be well in excess of their true air volume needs. Such ventilation systems could be considered as uneconomic, and to remain competitive the ventilation design needs to improve while the mines are trying to reduce energy consumption and their carbon footprints. This paper introduces a new mine ventilation design method where an underground base-metal mine’s ventilation system is designed by integrating discrete-event mining process simulation (DES) with mine ventilation modeling techniques. Furthermore, based upon the output data generated by means of discrete-event mining process simulations, the air volume requirement for the operating life of the mine is determined for “traditional” versus “activity-based” ventilation requirements. The output data generated through ventilation simulations are then used to quantify the economic and environmental benefits of an activity-based ventilation delivery system.

Jan 1, 2018

By W. Lin

When a large area of open gob collapses suddenly, a windblast is produced that can cause considerable damage throughout the infrastructure of a mine. In a few cases, the windblast has been accompanied by ignitions of methane and/or coal dust. This paper describes the conduct and results of laboratory tests involving the compression of mixtures of air, methane and coal dust under a falling weight and while allowing controlled escape of the mixture. The transient responses on pressure and temperature sensors were recorded. In addition to an analysis of those records, the paper highlights those conditions in which ignitions occurred.

Jan 1, 1997

By Luther W. Hyde

Ground water, one of Florida's most valuable resources, is also one of its most abundant. The State is fortunate to have several prolific ground- water reservoirs that yield tremendous quantities of water to wells and to some of the world's largest springs. These ground-water reservoirs, or aquifers are of two types artesian and nonarteaian. Ad artesian aquifer is one that contains water under sufficient pressure to rise above the top of the oontaining formation. A nonartesian aquifer is one that contains water which is not confined, and the upper water surface (water table) is free to rise and fall. The principal source of ground water in Florida is the artesian Floridan aquifer which supplies most of the water users in the State. Nonartesian sources include the Biscayne aquifer of southeastern Florida, the sand-and-gravel aquifer of extreme western Florida, and a shallow aquifer which lies at depths of less than 100 feet over much of the State. The accompanying map shows the approximate areas where these aquifers are the main source of supply; however, the boundaries do not represent the areal extents of the aquifers. For example, the Floridan aquifer extends beyond the southern boundary shown on the map, but it is not of great economic significance there because the water is highly mineralized. Aquifers other than the four described occur in the State, but they are, for the most part, of minor significance. One of these is an artesian aquifer which is formed by permeable zones that occur locally within the confining beds above the Floridan aquifer.

Jan 1, 1966

By Preston McGrain

Geologic maps are indispensable tools in the modern search for mineral and fossil-fuel resources. They are the first essential step in understanding the lithologic nature and structure of rock units that form the land surface and that lie beneath it. They provide the basic foundation for planning mineral resource exploration programs and form the superstructure from which subsurface investigations are projected. In view of the economic application of such maps, the Commonwealth of Kentucky and the Federal Government entered a formal agreement in 1960 to map Kentucky geologically on a scale of 1:24, 000, or one inch map distance equals 2,000 feet on the ground. A 7. 5-minute quadrangle would comprise the unit map area. A resolution which urged the preparation of a new geological map of the entire State was passed by the Kentucky Society of Professional Engineers in February 1959, and was presented to the Governor of Kentucky, the Legislative Research Commission, Kentucky Department of Economic Development (now Department of Commerce), Kentucky Chamber of Commerce, and Kentucky Geological Survey with a request for support and action. The request was subsequently endorsed and actively supported by numerous civic and professional societies as well as representatives of various facets of Kentucky government, commerce, and industry. Monies to initiate the program were appropriated by the next session of Kentucky legislature; this appropriation was matched by federal funds (Hagan, 1961). Kentucky's state-wide topographic mapping project was completed in 1956, just four years prior to starting the geologic mapping program. The recently completed modern 7. 5-minute, 1:24,000 topographic maps made ideal bases for plotting areal geology. Had they not been available, it is doubtful if a geo- logic mapping program so large and comprehensive could have been undertaken.

Jan 1, 1966

By Michael D. Loy

This paper examines the computerization steps of United Coal Company of Bristol, Virginia. OVERVIEW Producing close to 7,000,000 tons per year, United Coal Company is one of the most interesting mining companies in the east. Their approach to mining reflects a dedication to modern technologies and extraction methodologies. With varying amounts of production coming from four divisions (a fair amount of production comes from contract operators) and over a billion tons in recoverable reserves, United rests heavily on the planning and engineering efforts of a centralized engineering group. Although each division relies on its own engineering personnel for day-to-day management and operations, long range planning and reserve management is conducted at the corporate engineering level. This group, while extremely competent and efficient, is relatively small (7 people), when compared to the needs of a large mining company.

Jan 1, 1985

By J. Richard Tonry

In portland cement manufacturing, the raw materials axe changed to clinker in the burning operation. Generally the rotary kiln is used for this purpose and involves many processes, including pelletizing and nodelizing. This transformation is called clinkering, and is analyzed as now generally practiced in cement making, from the raw material to the resulting clinker.

Jan 1, 1963

By C. L. Karr

Establishing suitable control of pH, a requirement in a number of mineral and chemical industries, poses a difficult problem because of inherent nonlinearities and frequently changing process dynamics. Researchers at the U.S. Bureau of Mines have developed a technique for effectively controlling such systems. This technique successfully combines the process control capabilities of fuzzy logic and the search capabilities of genetic algorithms. Fuzzy logic offers an effective mechanism for handling nonlinearities, while genetic algorithms can provide fuzzy logic controllers with real-time adaptive capabilities. This Bureau-developed technique is applied to a laboratory acid-base neutralization experiment. Nonlinearities in the laboratory system are associated with the logarithmic pH scale and the changing process dynamics are due to alterations in pH and buffering capacity input solutions. Results indicate fuzzy logic controllers augmented with genetic algorithms offer a powerful alternative to conventional process control techniques in such nonlinear, rapidly changing systems.

Jan 1, 1992

By Myron W. Mellor

Much has been published concerning the subject of coal preparation as related to electric power generation however it is always a most vital topic for both utilities and coal producers, It also constitutes a field of study that is never finished since new concepts and changing demands continually require altered perspectives. One graphic illustration that has been used to emphasize the rapidity with which times are changing is the fact that during World War I, a station that consumed 1000 tons per day was looked upon as a large central station, while today some single generators require 1500 tons during the same period, For further emphasis, at that time a 20,000 horsepower turbo-generator was a mighty large machine; today, a unit of this size is planned for driving the boiler water feed pump required for a single large main unit. During the past ten years alone, electric utilities have more than doubled their percentage of coal consumed as compared to the total market. They now account for approximately 40% of the United States consumption and one-third of all production including export, Conversely, approximately 70% of all U. S. steam electric generation is by coal and this percentage is expected to increase. It is further predicted that utility consumption will increase from the current 160,000,000 tons per year to between 400 and 500 million tons in 1975 which is approximately equal to todays total production

Jan 1, 1959

By S. R. Stine

The Cyprus Thompson Creek Mine is located at 2,286m (7500 feet) elevation in the Central Idaho mountains, 61.16 kilometers (38 miles) southwest of Challis, Idaho off State Highway 75. The Thompson Creek molybdenum deposit lies near the eastern border of the late Cretaceous Idaho Batholith within a complexly deformed sequence of Paleozoic sedimentary rocks. Molybdenum mineralization is contained in a composite biotite granodiorite-quartz monzonite stock considered to be genetically related to the Idaho Batholith intrusive event. The ore is being mined by open pit methods and delivered to the concentrator stockpile with an overland conveyor belt system. The concentrator is designed as a 22,680 metric tons (25,000 ton) per day plant at an average head grade of 0.1% Molybdenum.

Jan 1, 1986

By Robert W. Elayer

For the design of a coal mine and process plant, a comprehensive foundation of geologic information is essential. Historically, the development, collation, and use of this information for design have been costly and time consuming. With the application of a digital computer, however, the effort expended can be reduced and maximum effective use of the geologic information realized. The purpose of this paper is to demonstrate the feasibility and convenience of using a computer to Store and manipulate geologic data for use in mine and process plant design.

Jan 1, 1975

By M. R. Yenchek

Faulty insulators on mine trolley/track haulageways may allow the flow of leakage currents into the mine roof and ultimately result in combustion of the local roof material. The National Institute for Occupational Safety and Health (NIOSH), Pittsburgh Research Laboratory (PRL), has devised a passive means to detect overheating insulators on direct current systems. The detector consists of a spring-loaded cartridge that ejects a reflective streamer of white Teflon tape when subjected to elevated temperatures. The cartridge assembly can be easily installed over the outer metallic shell of an existing trolley line insulator. If an insulator overheats due to ground leakage currents, the visible streamer alerts mine personnel traveling on the haulageway.

Jan 1, 1998

By Bjørn Nilsen

"INTRODUCTION/BACKGROUND Weakness zones or faults containing clay-rich gouge represent one of the most challenging rock mass conditions to be encountered during tunneling. In Norway, such conditions count for a large part of the rock support costs, and in cases where the rock support has been insufficient, serious instability and cave-in have in many cases been the result. Most commonly, such cave-in has occurred after water filling of hydropower tunnels, but in some cases it has also occurred in tunnels under excavation and in completed “dry” tunnels. To avoid instability, two important requirements have to be fulfilled: 1) The location of the weakness zone and its character have to be identified in time. 2) The rock support has to be sufficient to withstand the loading caused by the zone. An incident which really brought the problems related to swelling clay into focus was the cave-in at the Hanekleiv road tunnel in 2006. Here, rock fall from the roof as shown in Figure 1 occurred unexpectedly about 10 years after the tunnel was completed. Fortunately this happened at a time with very little traffic, and nobody was injured. This incident emphasized the significance of the issue of swelling clay, although it was found to be caused also by gravitational collapse of the clay-rich gouge material of the weakness zone, and not related to swelling only (Nilsen et al. 2007).In this paper, main focus will be on discussing the characteristic features of swelling clay, test procedures which are being used for characterizing swelling clay, and the reliability of the results from testing for use in support evaluation and design in conditions with swelling clay. It is generally well known that swelling clay may cause considerable pressure on support elements, but quantifying this pressure for reliable analysis and design of rock support is still a great challenge."

Jan 1, 2016

By P. M. Krishna

A five-year effort by the ASTM subcommittee E10.14 on Uranium Resource Evaluation has culminated in the approval of E901-82, Classification System for Uranium Resources. The standard classification was prepared with participation of representatives from the Dept. of Energy, the Dept. of Interior's Geological Survey and Bureau of Mines, utilities, and consultants. The classification of a resource is based on level of knowledge and the economic producibility of the resource at a given time. Alpha-numeric identifiers are used rather than words to avoid confusion with existing terms, definitions, and classifications. An effort is underway to develop estimation criteria to guide users in classifying a resource according to the above format.

Jan 1, 1983

By Raymond O. Dannenberg

Potential processes for the recovery of precious metals and copper from diverse types of complex electronic scrap were investigated. Leaching-type processes were not successful, and attempts to physically separate the various gangue metals and plastics from more valuable components were also unsuccessful. The most promising approach was a smelting process, followed by electrolytic treatment to separate precious metal from copper. Recovery of precious metals from the anode sludge may follow conventional procedures. An alternative to the above process is incorporation of the scrap with the concentrate fed to an industrial copper reverberatory or converter furnace, possibly preceded by direct melting to form an assayable bullion and dross.

Jan 1, 1970

By Thomas S. Mackey

The industrial types, sources, and quantities of USA tin residues are identified and the methods of treatment reviewed. The effect of a lower tin price, due to a current major world surplus of tin metal, is mentioned and covered in some detail. The names and locations of over 100 USA firms recovering tin residues are listed. Current smelting and refining charges are included to convert the residues into tin metal and alloy. The impact of the suspension of the LME daily tin price since October 24, 1985 to date, and the failure of the International Tin Council to support the Buffer Stock Manager are reported with comments.

Jan 1, 1986