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By K. N. Han

Coal is becoming increasingly important as a major energy source in the face of the world's depleting energy mainly based on oil reserves. Coal is by far the most abundant fossil fuel both in the United States and abroad. Currently, because of increased mine mechanization, the fineness of preparation plant feed is increasing. Further, in the future as the grade of coal diminishes and the sulfur content increases, upgrading preparation of coal is very important. Because the density of coal is less than that of rock materials that occur as impurities, coal is separated from such waste largely by gravity-controlled processes for particle size between 5 inches and 28 mesh. If the size of coal particles is below 28 mesh, froth flotation is a good method for upgrading fine coal. Previously, numerous investigators have tried to upgrade coal values by froth flotation(1-16) and have achieved moderate success. However, the recovery and grade of coals in the concentrates are not always satisfactory, especially when the particle size is small. In general, when the size of coal is below 100 mesh, the above methods suffer from poor grade and low recovery. The reason for this is that as size decreases, the effects of gravity diminish, and other forces take effect.

Jan 1, 1985

By D. G. Krige

I read the paper “The jackknife approach” with interest. There appears to be a widespread misunderstanding of the kriging variance as a measure of the error variance of the kriged grade estimate of an ore block. Virtually all mineral deposits display skew frequency distributions and are subject to the well-known proportional effect. Thus, it is usual to find in an ore body, when subdivided a really into subpopulations, that the variances of the grades (or the total sills of the variograms) for the subpopulations will be correlated with the corresponding mean grades (usually linearly with the squares of the mean grades). Thus, the variogram will be stationary.

Jan 1, 1996

By S. S. Peng

In this paper, the precise definitions for a number of commonly used subsidence parameters are given. The subsidence parameters have been determined using an integrated approach for 110 subsidence cases collected in the major US coal fields. Attempts have been made to establish empirical formulae for the parameters. The results of this study indicate that some traditionally-held concepts should be changed.

Jan 1, 1995

By McCarthy. Richard E.

The prime movers of the Centralia Project, the surface coal mine and the power plant, private utilities are very aware of public attitudes. They have established and maintain the reputation for leadership in public service and are genuinely concerned that this project initiate the pro-grams and design the hardware to answer the question :What will be the impact of the mine and the plant on the physical environment, i.e., the air, soil and the water." So in the beginning almost as soon as the decision had been made to go ahead with the project, officials of the two private utilities, Washington Water Power and Pacific Power & Light went on record and publicly stated time and again that the overall approach of the Operators would be to do all that was reasonably possible to safeguard the environment. This attitude became part of the thinking of the project planners, part of the design of the power plant and part of the plan for the surface mine. The coal to be mined is from the Skookumchuck formation. The formation is Late Eocene and is made up of poorly consolidated marine and non-marine deposits. The major overburden removal equipment is a bucket-wheel excavator -conveyor system and a 56 yard dragline. Mining of the coal will be done with truck and shovel. The coal is processed, washed and crushed to 1 ¼ " for delivery to the power plant. The muddy water created by the washing process is chemically treated and the solids removed by a thickener-vacuum filter system.

Jan 1, 1971

By W. A. Haley

Wheel loaders were first introduced shortly after World War II as small machines designed for handling loose materials in various industrial and processing applications. It was not until the early 1950?s, however, that machine size permitted widespread loading of loose or stockpiled material into on-highway type trucks. An ever increasing number of machines continue to be used for this purpose today. In fact, it is by far the major use for wheel loaders in mining and quarrying. Many of these loaders were working at mines or quarries handling in-process or finished material and some were doing shovel clean-up. It was quite natural then, when the primary pit loading shovel was down, to attempt to maintain some production by replacing it temporarily with the wheel loaders. Most of these attempts were not very successful, however, until the really large wheel loaders, 4- to 6-yd. size were introduced in the early 1960's. Since that time these machines have proven they can be productive and economical primary pit loading tools, a job that was once the exclusive domain of the power shovel. To be competitive with the shovel however, conditions must exist or be made to exist, that will be favorable for the wheel loader.

Jan 1, 1967

The rheological behavior of high concentrated coal -water slurry (cws), a new liquid fuel, is an important factor in the preparation, transportation and combustion. The conventional viscosimeters designed for Use with true fluids are not suitable to the measurement of the rheological behavior of cws. So that a special viscosimeter of tube type for cws was designed and set up in .laboratory. Experiments using two kinds of cws from two provinces from P. R. Olfna were conducted. It is found from test results that the experimental cws possess the rheological character of Bingham fluid and there is the existence of the wall effects which causes the measurement errors. In our former paper published the wall effects were discussed III the light of methods of Odroyd and Jastrzerbsiki to make the correction of the experimental results. But a number of tests are necessary to meet the need of determining the slip coefficient. In this paper the models of the wall slip velocity and the thickness of the slip layer of Bingham fluid were proposed III in theoretical approach which were satisfactorily used in the correction of the measured results of the rheological character of cws.

Jan 1, 1994

By Michael MacMillan

AI is already changing how mining companies are seen, judged, and trusted. This paper discusses “reputation engineering,” a structured way to build trust in a world where AI systems summarize and evaluate everything a company says publicly. Using mining examples, emerging AI search trends, and real communication work, the paper explains why the next 12–18 months are a crucial window for action. It also provides a practical framework to help mining companies improve their visibility, accuracy, and consistency across both human and machine channels.

Feb 22, 2026

By J. Paraszczak

Metal mining at great depths presents a number of serious challenges for mine operators. Among them is the high demand for fresh air required to cool down mine openings, evacuate noxious gases and contaminants and provide sufficient amounts of oxygen for miners. At the same time, modern mechanized mines extensively use diesel-powered load-haul-dump (LHD) machines, trucks and other mobile equipment. These vehicles not only emit exhaust gases and diesel particulate matter (DPM), but constitute an additional source of heat. As mine regulations get steadily more stringent with regard to air quality, the use of diesel engines has an additional adverse impact on ventilation costs. In this context, the present paper examines possible alternatives for diesel power trains, both those commercially available and those in development. They are reviewed with regard to their principles, required infrastructure, stage of technology development and progress. The questions of their flexibility, practicality and economic viability are also addressed. Finally, their possible benefits and potential for implementation in the conditions of deep metal mines are discussed. The paper concludes with short- to medium-term predictions concerning promising drive alternatives for vehicles destined to operate in deep metal mines.

Jan 1, 2009

By Bjorn Olsson

"Heavy impact. High frequency hammering. Extreme abrasion. Building on the experience of owning and operating its own mines, Ovako has developed a deep knowledge of how vital the right steel properties are in withstanding the extreme loads encountered in every part of the drill string. That is why Ovako’s product development process is focused on understanding the specific load cases and manufacturing operations associated with rock tools.The punishing conditions of percussive drilling can push the limits of most materials. And heavy mechanical loads are only the beginning. Highimpact energies at high frequency are a major source of fatigue. High temperatures result from impact energy losses. And abrasive, erosive and adhesive wear are constant risks. Handling any of these varying demands at a single point along the drill string is difficult enough — which makes optimizing for the entire drilling system an extremely complex challenge. Engineering for specific loadsOvako has specialized over many decades in analyzing the dominant loads for each of the parts and components used in rock tools, and testing for individual applications in its laboratories. The most critical fatigue properties are controlled through the steel metallurgy, and supported by performance measurements through extensive rotating bending fatigue (RBF) testing, along with special methods that combine impact load with various wear loads. The result is a fit-for-purpose steel with tightly controlled performance properties, making it possible for customers to precalculate the expected life time of their components for highly automated and repetitive processes Tailoring steels for the processing route.The same levels of control and predictability must be carried through to the customer’s own manufacturing processes. By ensuring minimal variations in chemical composition, everything from heat treatment and welding to automated machining can be carried out with high consistency. With precisely controlled material properties based on an existing processing route and exact load case, customers are able to minimize their total tool production costs while ensuring optimal performance for their end products. Development of Hybrid SteelBuilding on this experience in the mining industry, Ovako has developed a new steel family, known as Hybrid Steel, designed to meet the demands of high-stress, elevatedtemperature applications where mechanical and fatigue strength are critical. Traditionally, steels for these applications are produced by expensive small-batch processes. Hybrid Steel, however, enables high volume production at a competitive cost.The world of steel has traditionally been divided into clearly separated categories of tool steel, stainless steel and lower alloy engineering steel. Hybrid Steel is now challenging that division, offering attractive properties from all three categories."

Jan 12, 2017

By Ben W. Burdett

Since the late 19701s, the use of microcomputers in the minerals industry has grown to the point where today they can be found in virtually every plant within the industry. Their use in every aspect of instrumentation and control has increased the ease of operation and control of every phase of mineral processing. Their incorporation in sensors, transmitters, indicators, and controllers in addition to their use in distributed control and computer systems has provided operators with more timely accurate information than they have ever had before. This has led to an increase in the operator's effectiveness and an improvement in overall productivity. The ultimate aim of plant control is to maximize recovery in the mineral processing operation, and the microcomputer has spawned many tools that are now making this goal attainable. This paper discusses individual use of microcomputers in the areas previously mentioned as well as their collective use in overall control systems. The incorporation of local control systems in total plant control including the communication of information throughout all levels of plant management is also discussed. Finally the role the microcomputer is playing in today's plants is illustrated with numerous references to current examples.

Jan 1, 1985

By J. E. Gebhardt, D. King

Field-testing of a new on-stream X-ray fluorescence analyzer was conducted in a copper concentrator. The evaluation of copper tailings and concentrate streams indicated a statistically acceptable correlation with laboratory chemical analyses. The new equipment employs a “components off-the-shelf” approach to minimize capital cost and maintenance issues and to utilize the latest advancements in X-ray fluorescence detector technology and computer capability. A general description of the system is provided, and performance of the analyzer measuring copper (Cu), iron (Fe), and molybdenum (Mo) is presented.

Jan 1, 2003

By V. Rajaram

The oil shales located in the Appalachian Basin cover an eight-state area of the eastern U. S., and are referred to as Devonian (black) shales. These shales have been exploited for their gas potential for several years. The Institute of Gas Technology (IGT) has conducted research since 1972 on the production of shale oil from the Devonian shales, and this resulted in the development of the HYTORT process. This process demonstrated that the yield from the Eastern oil shales can be greater than the value indicated by the Fischer assay method. IGT estimates that 423 billion barrels (67.3 x 109 m3) of oil could be recoverd by HYTORT processing of surface-minable eastern U. S. shales. Recently American Syncrude Corporation and Southern Pacific Petroleum N. L. have proposed oil shale projects in Kentucky. This paper will describe the surface mining and retorting techniques that have been studied for exploitation of the Devonian shales, and enumerate the problems that have to be overcome before commercial production can be realized from these shales.

Jan 1, 1983

By Pramod C. Thakur

Coal is a major source of energy in the world today and will, undoubtedly, continue to be so for the next few centuries. Naturally, a great number of studies has been made of its physical and chemical properties. Unfortunately, the work on technical properties which influence the mining of coal and the consequent yield of inflammable gases and respirable dust particles has not progressed at a comparable pace. Coal is a brittle material. Irrespective of the mechanism of breaking coal, some dust is always produced. In mining parlance dust is defined as solid particle, smaller than 100 microns (micron = 10-6 meter), in size Coal dust, when raised into a cloud, creates two well known hazards in mines, namely, the coal dust explosion and Coal Workers' Pneumoconiosis (CMP). The latter is, perhaps, the greatest environmental hazard in U.S. coal mines today. In this context it is not only natural but also necessary to investigate the proneness of a coal seam to respirable dust production. It has been established that the amount of dust produced is a function of two groups of variables (1), (2), viz. (1) Material dependent variables, e.g., moisture content, compressive strength, hardness, etc. (ii) Breaking mechanism dependent variables, e.g., type of machine, depth of cut, etc.

Jan 1, 1973

By D. S. Yantek, L. A. Alcorn, M. J. Lowe, H. E. Camargo

U.S. National Institute for Occupational Safety and Health (NIOSH) studies show that 43.5% of surveyed coal preparation plant workers had noise exposures exceeding the U.S. Mine Safety and Health Administration permissible exposure level of 90 dB(A). Sound levels around vibrating screens in these plants often exceed 90 dB(A). NIOSH is currently developing noise controls for horizontal vibrating screens. To characterize noise sources, NIOSH researchers performed sound pressure level (SPL) measurements on a vibrating screen at their Office of Mine Safety and Health Research laboratory in Pittsburgh. The results show that the entire screen contributes to noise below 1 kHz, and the vibration mechanism housings are most significant above 1 kHz. Constrained layer damping (CLD) treatments and an enclosure were used to reduce mechanism housing noise in this range from 1-10 kHz. These were evaluated using sound power level measurements according to ISO 3744. The CLD treatments reduced the A-weighted sound power level by 3.1 dB in the 1 to 10 kHz one-third-octave bands. A panel-on-frame vibration mechanism enclosure using various types of panels further reduced the A-weighted sound power level from the CLD configuration in the 1 to 10 kHz one-third-octave bands by 3.7, 4.0, and 3.9 dB for aluminum, steel, and Dynalam™ panels, respectively. The combination yielded a 7 dB reduction from baseline in A-weighted sound power for the same frequency range.

Jan 1, 2011

By R. F. Davis

The evaluation and selection of coals for producing metallurgical coke is indeed a com- plex process simply because coal is a complex and variable substance which is sensitive to how it is treated from the time it is mined until it is transformed into coke. A review of the the more common evaluation tests made on coal and how the test results are applied in commercial practice. Parameters used to select coal blends for wet and preheated charges should also be of interest.

Jan 1, 1980

By Arshad Ali, Mudassar Khan, Waqas Ahmad, Nisar Muhammad, Muhammad Salman

Talc is an important industrial commodity due to its wide-ranging intrinsic properties; however, the presence of iron oxide hinders its industrial utilization. Herein, we report the purification of Pakistani talc through acid leaching assisted by chlorination techniques. Among various acids (i.e., HF, HCl, H2SO4, HNO3, H3PO4, Aqua Regia, H3BO3, and CH3COOH), HF was the most effectual, removing up to 67% of iron oxide at optimized conditions of temperature, 90–95 °C; time, 120 min; HF concentration of 5%; and at a pH of 1. In the second step, chlorination of the talc sample was performed separately by both wet chlorination and dry chlorination. Wet chlorination was carried out using KMnO4 and HCl in slurry phase which shown about 52% removal of iron oxide, whereas dry chlorination with CaCl2 at high temperature attained about 48% removal of iron oxide from talc sample. Further, the wet chlorination of HF leached samples was also performed under optimized conditions which showed up to 87% iron oxide removal. The original and treated talc samples were characterized by EDX and XRD analysis to monitor the changes in the elemental and mineralogical composition of the talc. It can be concluded that HF leaching followed by wet chlorination is an effective method for the upgradation of low-grade Pakistani talc ores.

Aug 9, 2021

By H. Shafick Hanna

The major problems are identified the high phosphorus content and the fine dissemination or encapsulation of mineral impurities, in, ,the iron bearing minerals, A process which combined extreme fine grinding techniques with magnetizing roasting or flotation separation methods, is suggested. By these methods concentrates assaying 60-61 percent Fe exceeding the widely accepted upper limit of 56 percent Fe set for these ores, were produced with 75-90 percent iron recovery. Moreover it was shown that the phosphorus content of these concentrates could be reduced from 0.25 to 0.03 percent phosphorus by acid leaching. A brief discussion on production costs based on current and future developments in iron ore processing is given.

Jan 1, 1980

By Virgil W. Carmichael

In the Fort Union formation of western North Dakota, eastern Montana and northeastern Wyoming there are immense tonnages of lignite and subbituminous coal that have not yet been evaluated in terms of present economic conditions. Continued expansion of United States energy requirements has focused ever increasing attention on this tremendous resource, particularly as efficiency in mining and transporting of coal, as well as in electrical energy generation and transmission have improved and as hydrogenation and gasification of coal approach economic feasibility. This "total energy" concept for coal includes all of the energy uses that coal offers and has resulted in mergers of oil and coal companies and acquisition of coal re- serves by oil companies, as well as by coal companies and others. There is no doubt that these coals are entering an exciting new era of exploration and development that will result in greatly increased production. As a matter of fact, increased consumption for energy generation is well under way and recognition of the economic feasibility of high-Btu pipeline gas and synthetic petroleum products from coal is imminent. As coal is gradually displaced in steam electric generation by the more exotic fuels and processes, it will be increasingly used as raw material for the synthetic petro-chemical industry and the organic chemical industry.

Jan 1, 1968

By L. Zhou, J. P. Rider, T. W. Beck, J. A. Organiscak, Y. Zheng

The National Institute for Occupational Safety and Health’s Office of Mine Safety and Health Research recently developed a series of models using computational fluid dynamics (CFD) to study the gas distribution around a continuous mining machine with various fan-powered flooded bed scrubber discharge configurations. CFD models using Species Transport Model without reactions in FLUENT were constructed to evaluate the redirection of scrubber discharge toward the mining face rather than behind the return curtain. The following scenarios are considered in this study: 100 percent of the discharge redirected back toward the face on the off-curtain side of the continuous miner; 100 percent of the discharge redirected back toward the face, but divided equally to both sides of the machine; and 15 percent of the discharge redirected toward the face on the off-curtain side of the machine, with 85 percent directed into the return. These models were compared against a model with a conventional scrubber discharge, where air is directed away from the face into the return. The CFD models were calibrated and validated based on experimental data and accurately predicted sulfur hexafluoride (SF6) gas levels at four gas monitoring locations. One additional prediction model was simulated to consider a different scrubber discharge angle for the 100 percent redirected, equally divided case. These models identified relatively high gassy areas around the continuous miner, which may not warrant their use in coal mines with medium to high methane liberation rates. This paper describes the methodology used to develop the CFD models, and the validation of the models based on experimental data.

Jan 1, 2015

By W. D. Keller

Scan electron micrographs, SEM's, will be shown of representative refractory clays from Missouri deposits, with counterparts from other localities. The story is in the pictures, ("1000 words in each picture"), but clay types include the following. Plastic, semi-plastic, and semi-flint "fire clays" of Missouri have textures which appear to retain certain relic texture of ball clay. Flint clay is composed of tightly interlocking packets, sheaves, and books of kaolinite. Diaspore and boehmite mineral textures characterize those "clays". Surface-boulder diaspore shows very pronounced recrystallization and crystal enlargement from original, unexposed first-grade diaspore.

Jan 1, 1977