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This paper presents the development of a knowledge based integrated decision support system (E.X.I.S) for the extractive industries to provide information concerning the environmental impact of extractive operations on land quality, surface and ground waters, and the best solutions for the rehabilitation/revegetation of the waste disposal areas to the relevant target groups (extractive industries, regional authorities, national authorities, research institutes, public). GIS was integrated with the decision-making models for the rehabilitation and revegetation of mine spoil. The system design involves several steps including site selection ? mine type identification ? waste identification ? selection of rehabilitation (revegetation or other methods). The knowledge based model consists of two integral parts: the model base, in which the input data are processed and classified using special fuzzy algorithms and criteria and the knowledge model, which hosts the various decision algorithms concerning evaluation of vegetation covers, selection of trees and plant species, selection of rehabilitation and revegetation schemes and also economic analysis for each option. The system input will include parameters on site characteristics (climate, topography, geology, hydrology etc), waste type and properties (physical-geotechnical and geochemical data) as well as environmental parameters of the existing waste disposal area. Based on the values of the above parameters and the characteristics of the rehabilitation technologies developed worldwide, the system, using IF-THEN rules will define a list of appropriate techniques for the rehabilitation of the examined waste. Then, the model will involve the application of multi-criteria analysis (MCA), i.e. a structured system for ranking alternatives and making selections and decisions. Each technique shall be judged based on its behavior into four fields, i.e. financial, social, technical and environmental criteria. In turn these fields will be analyzed into a lower level of evaluation criteria.

Jan 1, 2006

By Sean Harvey

One of the manifestations of the dynamically induced failures in deep coal mines is the violent ejection of coal from the ribs. A possible protection against such failures is the use of a specifically designed dynamic support system with reinforcement units having the sufficient capacity to absorb the kinetic energy of the dynamic failure and a skin support that can adequately contain the disintegrated coal. With this method of mitigation in mind, a recently introduced yielding rock bolt, trade name Roofex, has been identified (Harvey and Ozbay, 2009) as a possible energy absorbing component of a dynamic support system. According to the manufacturer?s specification, the Roofex bolts can yield 300 mm (or more) displacement while holding 80 kN pull load. In order to assess the performance of this support unit in coal ribs, a series of in situ pull tests performed in two coal mines in Colorado. The results show that, under conventional pull test loading conditions, Roofex yielding bolts perform very close to their claimed specifications, thus showing a potential for their use as the main energy absorbing component of a dynamic support system. Further studies are required to confirm the in situ performance of these bolts under dynamic loading conditions and also to develop a containment component for a dynamic support system for the mitigation of dynamic coal rib failures.

Jan 1, 2009

By A. Founie

The United States continues to be the world’s leading producer and consumer of diatomite. Production of diatomite in the United States during 2005 was estimated to be 653 kt (720,000 st). This was a 5-percent increase compared with 2004. The value of processed diatomite in the U.S. was about $179 million in 2005. Production was from six companies with 12 processing facilities in four states. California and Nevada were the principal producing states. They accounted for about 70 percent of U.S. production in 2005. U.S. diatomite exports were about 144 kt (159,000 st). Imports were negligible. The internal structure and chemical inertness make diatomite an excellent raw material for filtration, absorbent and filler applications. Filtration, especially the purification of beer, liquors and wine and the cleansing of greases and oils, continued to be the largest end use for diatomite. Other applications include the removal of microbial contaminants, such as bacteria, protozoa and viruses in public water systems, and the filtration of human blood plasma. The use of diatomite as fillers and in pharmaceutical applications, including the filtration of human blood plasma, continues to increase as has its use as an insecticide base and as pozzolan. The relative rank of end uses of diatomite were filter aids, 75 percent; fillers, 11 percent; absorbents, 7 percent and other (mostly cement manufacture), 7 percent.

Jan 1, 2006

By Sidney A. Suhler

The persistent requirement for methods and equipment capable of detecting hazardous anomalies in advance of underground mining has led to the development by the U.S. Bureau of Mines of a directional radar probe. The probe operates from boreholes drilled from the surface into the underground region to be mined. The engineering model radar was completed in early 1982 and field demonstration tests were performed in May of that year at a selected coal mine. Preliminary in-situ electromagnetic tests were performed at several candidate coal mines to evaluate the radio-frequency characteristics of the coal. A coal mine in New Mexico was selected on the basis of low EM propagation losses in the coal and the presence of an extensive coal seam displacing fault as a radar target. The borehole radar was operated in two vertical boreholes which intersected the coal seam at approximately 25 and 40 feet from the fault interface. Radar reflections from the coal/ rock interface were detected in both tests. Underground tests in a horizontal borehole in the coal were less successful because of interfering reflections. Additional borehole-to-borehole tests were performed with a separate ground penetrating electromagnetic system to obtain radar range calibration data. The coal was found to be bounded by very lossy roof and floor sandstone and shale while propagation through the coal seam was obtained at distances up to 175 feet between test boreholes. Coal seam continuity was indicated by the hole-to-hole experiments through a section of the seam previously thought to be completely cut off by the fault.

Jan 1, 1983

By E. Woodburn, H. W. Smith, M. C. Fuerstenau, R. Putman

This paper presents a review of developments to date in computer control practice, based in large part on Canadian experience. The basic problem examined is that of stabilizing control; matters considered are control strategies, hardware and software aspects of system implementation, reliability, human factors, and economic results.

Jan 1, 1976

By E. J. Duggan

In the course of the grinding experiments conducted at Climax over the past twenty years one interesting phenomenon was discovered. This was that balls made of certain types of steel grind more ore than some others. The most significant variation was found in the results secured with a hard alloyed forged bail compared with the forged carbon ball supplied by most ball manufacturers These findings were confirmed in many repeated controlled tests. The value of these tests depends on the methods used, the facilities available and the care with which the investigations were conducted. These are described in the following. This testing has largely been done in eight 91 x 81 low discharge ball mills in closed circuit with 7811 duplex screw classifiers. The mills run at 20 RPM on a feed approximately minus 3/8 inch. The ore is ground through 28 - 35 mesh in one stage. Each mill and auxiliary classifier is in a separate, parallel grinding and flotation section The, ore to each: section is the same in every particular and is fed to each mill bin from a common conveyor tripper. The ore from the bin to the ball mill is weighed on a conveyor scale. The power input to each mill motor is determined with a watt hour meter which measures the power to the mill motor only. Both the scales and meters are checked periodically by standard methods and have been found to give consistent readings. Automatic samplers are employed on each section to obtain accurate measurement of the size reduction. A size analysis of the classifier overflow is made each shift and a composite size analysis is obtained from a weighted average of the various shift analyses. The mills are driven by 450 horsepower synchronous motors so that there is no speed variation and shell liner age is kept as nearly the same as possible in mills under test. The same set of operators is assigned to a mill under test as to the control mill. In all other particulars such as ball load, mill density, liner design, etc., the mills are operated in precisely the same manner. This is an ideal arrangement for plant testing. From observations of ball mill performance over the past twenty years, it is the opinion of the operating staff that variations of as little as one to two percent in mill capacities may be determined if sufficient operating hours are devoted, to a test. Relations between mill capacities, fineness of grinds and power consumptions have been established with a high degree of accuracy. In Table I are given the figures for one test. These show that while the grind with the hard ball was slightly coarser, the tons ground per hour was 5.4 percent greater with the soft ball, and 6.1 percent greater on the basis of minus 100 mesh produced. The power consumed per ton with the hard ball was 4.4 percent greater on a tons per hour basis. The soft ball was inferior in wearing qualities and steel consumption per ton of ore was 24 percent greater with it. In this test the mills were charged with the two different balls for a period of three months to allow the ball loads to come to equilibrium. In Table II are given the specifications of the two balls. The difference in grinding rates may be accounted for by the nature of the ball surfaces. The surfaces of the soft balls after being worn a while are rougher to the touch. Enlarged photographs of the worn-in surfaces of hard and soft balls are shown in Figure I. These show the presence of scratches or skid marks on the hard ball surface which indicates less nipping effect. The Climax ore pulp has a pH of 6.0 and is in a dispersed state. The viscosity is low compared with most ores especially those that are conditioned with lime. This would lower the tendency of the pulp to adhere to the balls with a lower grinding efficiency as a result. It was also thought that the relative rates of wear from surface to center might affect the make-up of an equilibrium ball charge. This probably has little effect on capacity as shown by the size analyses of the two ball charges in Table III. This hypothesis was subsequently investigated by the use of rationed charges. The rationed charge did not overcome the advantage in

Jan 1, 1958

By S. C. O?Brien

This paper develops the procedure for simulating the special locked-cycle Work Index laboratory test using the kinetic parameters obtained by conducting standard size-mass balance (SMB) grinding tests and presents the results for three materials - quartz, a taconite iron ore and a bituminous coal. It was found that the WI could be determined by simulation; however, if a material breaks abnormally, a full description of its abnormal breakage is necessary. It was also found that the sensitivity of the WI test procedure to the sieving process and the estimating of the 80% passing size of the sieve undersize is sufficient to question the practice of quoting a WI to two or more decimal places. Finally, if a material grinds abnormally in the Work Index mill, then the WI test should not be conducted.

Jan 1, 1987

By Takashi Sasaoka

About 200 M tons of coal were imported into Japan in 2007 and Indonesia was its second largest exporter, accounting for about 30 M tons (12% of the total imported coal). Indonesia produced about 200 M tons of coal, about 75% of which was exported in 2007. As the Indonesian government has decided on an energy policy wherein 33% of the country?s primary energy demand will be met by coal by the year 2025, the domestic demand for coal has increased dramatically in recent years. Over 99% of the coal produced in Indonesia comes from surface mines. However, the conditions of surface mines are worsening each year: the stripping ratio is increasing, approaching the economic ratio, and the infrastructure for coal from inland mining areas is insufficient for such intense mining operations. To meet the demand for coal in Indonesia and the rest of the world, underground mines have to be developed. However, mining engineers and/or miners in Indonesia do not have a lot of experiences, expertise and know-how concerning the plans and operations of an underground coal mine. In addition, the industry faces a lot of problems which include poor conditions such as a steep coal seam, groundwater problem, stability of highwall, etc. Under these situations, a mine targeted in this research attempts to develop a new underground mine from an open-cut highwall because the stripping ratio in the surface mining area has almost reached the limitation of economic value. This paper discusses the possible development of a new underground coal mine from an open-cut highwall by means of field observation and numerical analysis.

Jan 1, 2009

Careful financial analysis of capital investments has always been a vital task in mining which is one of the most capital intensive sectors of the economy. Furthermore, mining costs have leapt ahead at an astonishing rate in recent years not just due to accelerated inflation, which affects everyone, but also due to the imposition of enormous costs of enviromental regulation and the continuing decline in ore tenor. Not only have unit costs risen, but the amount of effort expended to recover a pound of metal has increased due to the inexorable decrease in ore grades. New low-margin, high-volume mining investments place increasing importance on sound financial planning. Owing to the enormous investments involved, a greater share of individual corporate resources is committed to these projects than is normally the case in other industries. Thus, the consequences of failure are extremely grave, and a close examination of all inputs to the evaluation equation is clearly indicated.

Jan 1, 1979

By Chee Theng

"In 2013, Coeur Mining had more than $55 million in general and administrative (G&A) costs and less than $100 million in cash flow. This year, its G&A costs stand at $30 million, down by more than 40 percent, its all-in sustaining costs have shrunk by more than 30 percent, and its cash flow is above $200 million. To realize this, the company aggressively reduced both its corporate overhead cost and operating cost and repaid more than $300 million in debt.The more robust balance sheet meant the precious-metals producer was well positioned to reap the rewards of an upsurge in commodity prices in the early part of 2016. Its stock price soared from $1.75 in January to $15.98 in August. Although the stock price has since dropped to around $9 due to a stronger dollar and a more hawkish Federal Reserve that recently raised U.S. interest rates, shifting the opportunity-cost argument away from buying gold and silver, Coeur remains attractive to analysts in light of its prudent spending and improved fundamentals.Focus on balanced portfolioCoeur is the largest primary silver producer and one of the largest gold-producing companies in the United States and one of the largest silver companies in the world. Incorporated in 1928, the U.S.-listed company has a total of five operations: three in the United States, one in Mexico and one in Bolivia. About two-thirds of its revenue comes from the United States.The company is conscientious about having a balanced portfolio, so no single mine accounts for more than about 30 percent of its business. Being in three different jurisdictions provides further diversification, and its revenue split of about 60 percent from gold and 40 percent from silver gives it some metals mix. This year, it expects to produce about 466 t (15 million oz) of silver and 10.3 t (330,000 oz) of gold."

Feb 1, 2017

As the surface reserves are being depleted, more and more stone operators are seeking underground mining options. Stability of underground openings is a major concern for the safety and productivity. This paper relates to a field study conducted at a large underground limestone mine in Central Pennsylvania. Identification of hazards leading to ground failures and assessment of roof fall risks are important in mitigating injuries. Field observations at this mine were integrated with Roof Fall Risk Index (RFRI) mapping software recently developed by West Virginia University. The system is designed to combine field study data related to geologic factors, mining-induced damages, roof profile, and ground water influx to generate RFRI maps. The mine has adopted a proactive ground control program consisting of comprehensive examination of drilling and bolting logs; precision surveying of roof and rib; accurate mapping of cutters, falls, and geologic structures; and installation of extensometers and microseismic monitoring systems. Investment of time and resources has eliminated fatalities and lost-time injuries due to ground fall. This paper presents the geologic settings, mining conditions, ground control issues along with risk management and control techniques adopted at the study mine.

Jan 1, 2009

By David Crouthamel, Raymond Henn

"The need to fill the void space or annulus created between an excavated tunnel or shaft and the final lining system has long been a requirement in underground construction. Most of those types of voids are created as a result of employing the two pass tunneling lining method. Filling of this void is called backfilling. For many years the materials used as backfill were primarily reinforced and non-reinforced concrete, sanded grout, neat cement grout, or blown-in sand/pea gravel. However, in the past 20 years the use of cellular grouts/cellular concrete as the backfill material has greatly increased. Most cellular grout is made of a mixture of water, Portland cement (with or without the addition of fly ash), a foaming agent and admixtures such as a water-reducer or superplasticizer.It is the authors’ preference to use the term cellular grout as opposed to cellular concrete since by ACI Concrete Terminology an ACI Standard (ACI CT 13), concrete contains aggregates. Normally cellular grout does not contain sand (finite aggregate), but almost never contain course aggregates.The authors believe there are several reasons for this increased use of cellular grout as backfill, such as:• The increase utilization of the various trenchless tunneling methods. Tunnels constructed using trenchless method tend to be smaller in size, excavated diameter or cross sectional area. Making man-entry for placing backfill from inside the secondary liner, utilizing pre-installed grout posts, more difficult if not impossible. It is these workspace restrictions that are the drivers as to when to utilize grout ports installed during the pipe/liner fabrication versus grout delivery pipes installed within the void/annulus space.• The ability of cellular backfills to be pumped and flow longer distances.• The unit weight of cellular grouts can be controlled by mix design and generally can range from 560 Kg/m3 (35 lbs/CF) to 1040 Kg/m3 (65 lbs/CF)."

Jan 12, 2017

By A. A. Mular

Examining a typical curriculum for mineral process engineers shows that traditional subjects remain important, namely, engineering, earth and basic sciences, mathematics and mineral proc¬essing technology. However, Table I shows additional subjects that may be woven into a modern curriculum, because of micro- and macro-engineering advances over the years. The ways to incorporate these subjects into the curriculum will vary from school to school. Such changes are in response to evolutionary technological and political needs as determined by society and business. Beginning with the 1950s, engineering empiricism was strengthened through micro-engineering, where fundamentals and mechanism serve as foundations. Scientific apparatus unique to the basic sciences (Zeta meter, FTIR spectroscope) was adapted to test new hypotheses. Coincidentally, as computers became more available, complex differential

Jan 1, 1992

By Henry Rumfelt

Strip mining in the domestic coal industry is contributing a greater proportion of overall production than at any time in the past. U. S. Bureau of Mimes statistics show that the percentage of total production mined in 1958 by stripping methods in- creased to more than 30 pct, up from 22 pct in 1951. The tendency to favor strip and open pit mining exists in other mining activities, but such trends are not as clearly outlined as in the coal industry. Significantly, the depth of overburden in coal properties considered suitable for stripping is also increasing. A depth of 50 to 60 ft of overburden was once considered to be about the maximum amount that could be handled economically, Today, a depth of 80 to 100 ft is frequently taken into consideration for simple overcasting operations (i.e., excavating over- burden and dumping it in the spoil position where it remains indefinitely). Significantly, the depth of overburden in coal properties considered suitable for stripping is also increasing. A depth of 50 to 60 ft of overburden was once considered to be about the maximum amount that could be handled economically, Today, a depth of 80 to 100 ft is frequently taken into consideration for simple overcasting operations (i.e., excavating overburden and dumping it in the spoil position where it remains indefinitely).

Jan 1, 1960

By Thomas B. Faddies

The Trixie mine is located in the East Mining District. Since production began in 1970 over 450 000 tonnes of ore grading 239 grams of silver, 6.9 grams of gold, and 1.2% Cu have been mined from veins in Cambrian Tintic Quartzite. Detailed geologic mapping and extensive sampling are essential for compiling the data base required for efficiently developing and mining known reserves as well as planning exploration and development work. Although the basic techniques used by the geology group at the Trixie were developed many years ago, the reduced activity in underground precious metal mining in the U.S. have made these techniques less familiar to many presently active geologists. The increased activity in precious metals search and exploration again offer cause for the application of these techniques as a prerequisite to efficient exploration, development and production.

Jan 1, 1983

By J. Groppo, W. Zhang, R. Honaker

"Rare earth elements (REEs) found in coal are in the form of minerals, ion-substitution with clays and organically bound. Rare earth minerals (REMs) such as monazite exist in coal and have a grain size less than 5 microns. Froth flotation was successful in concentrating REMs existing in a thickener underflow material derived from Fire Clay seam coal which contained around 300 ppm of rare earth elements (REEs). Conditioning with fatty acid followed by processing using multiple stages of conventional flotation produced a final concentrate containing 2300 ppm REEs. Using a laboratory flotation column, a concentrate containing around 4700 ppm of total REEs was produced equating to an enrichment ratio of 10:1. INTRODUCTION Rare earth elements (REEs) are becoming increasingly important and have been widely used as raw materials for the production of phosphor, metal catalysts, magnets, and batteries [1, 2]. REE recovery from alternative sources such as coal and coal by-products has the potential to stabilize the economic viability of coal mining operations while providing a dependable supply of critical materials. The average REE content of the world coal is around 60-70 ppm [2]. There are many well-known coal beds with high contents of REEs such as those in the Far East coalfields in Russia (300-1000 ppm), the Fire Clay coal seam in eastern Kentucky (500 ppm), and the Sydney Basin in Nova Scotia, Canada (72-483 ppm) [3-6]. The occurrence of REEs in coal and coal by-products can be classified into three types, i.e., rare earth minerals such as monazite and xenotime, ion exchangeable REEs in clays, and REEs associated with organic matrix. The particle size of the rare earth (RE) minerals in coal and coal by-products is very small and normally in the micron and/or nanometer scales. The flotation technique, which is based on the surface chemistry difference, has been widely used to treat fine rare earth industrial minerals such as monazite, xenotime, and bastnaesite [7-11]. As such, flotation is a promising method for the concentration of REEs from coal and coal by-products. In the current study, rare earth flotation was conducted using the fine coal refuse generated at an operating coal preparation plant treating coal from the Fire Clay seam. REE concentration by flotation required an appropriate amount of grinding and control of the pH value while using typical collectors. Prior to RE concentration, release tests were conducted to evaluate the floatability of the recoverable coal and the REE distribution in the flotation fractions in the fine refuse. Mineralogy of the REE was studied using SEM-EDX."

Jan 1, 2017

By Jeffrey K. Whyatt

The Crandall Canyon accident investigation included an interesting and unexplained observation by rescuers that the ?barrier rib had shifted northward as a unit, as much as 10 feet.? This is not the first mention of such a movement, although such reports are rare. Historical accounts describe unusual movement and displacement of intact coal, cribs and timbers. Two movements of particular interest are the creation of gaps above coal pillars and falling of standing support elements without apparent damage. A dynamic boundary element program was used to explore movements induced by slip on geologic features removed from the affected panel. While the resulting models are much too simple to fully replicate these observations, they do show that the types of phenomena observed are possible. They can also provide insight into the types of motions that ground support elements are subjected to during large bump events. This was demonstrated for the case of a large bump in a Book Cliffs coal mine. Seismic information suggested the source mechanism to be normal slip on a fault. A model of that source showed initial dilation of the panel followed by dynamic compression and rebound ? consistent with underground observations. The initial dilation is important as it may allow slender standing support to shift or fall.

Jan 1, 2009

By Alexander N. Winchell

The cities of St. Paul and Minneapolis are located side by side on a double loop in the Mississippi River near the eastern boundary of Minnesota. Both cities lie on both sides 'of the Mississippi River, which in this region describes an S-shaped curve. The two cities together have a population of over 600,000 people, gathered in an area which has grown to be a single urban district inasmuch as the two cities have expanded until they occupy all the territory formerly between them, though the business centers are ten miles apart. St. Paul is located at the head of navigation on the Mississippi River and Minneapolis, farther upstream, at the Falls of St. Anthony. A recent water¬power development below the Falls of St. Anthony, constructed by the Federal Government, has at the same time made possible navigation to the foot of St. Anthony Falls through a lock around the dam which replaces the former rapids. Minneapolis, in 1920, had a population of 380,000 people, and St. Paul, 235,000. The two cities occupy land at an elevation of 700 to 900 feet above sea level. The average elevation is slightly less at St. Paul. Minneapolis has nearly 4,000 acres of parks and park¬ways, while St. Paul has nearly 2,000.

Jan 1, 1920

By I. L. Jennings

In most industrialized countries, the largest element of the mining industry in physical volume is that devoted to the extraction and processing of materials for use as construction aggregates. Required for all developments in industry and commerce, power and transportation, and housing and public services, their use is so widespread that possible sources are exploited throughout all geographic regions, as close as possible to the point of use. Thus, it is also the most frequently encountered form of mining throughout the world. These materials come from four main sources:- (a) Excavation of unconsolidated deposits of sand and gravel (b) Stone quarrying. (c) Processing of slags and other mineral wastes. (d) Manufacturing from clays and shales by heat fusion. The major uses are in: (a) Portland cement concrete, that most versatile of construction materials, including the many concrete products in current use. (b) Asphalt cement concrete; widely employed for paving roads, parking lots, airfields, etc. (c) Foundation materials, such as road base, granular backfills, railway ballast, etc.

Jan 1, 1968

By W. G. Pariseau

A study of coal pillar strength was done at the Beehive Mine during a three year period, 1974?1977, in a cooperative effort involving the University of Utah, RE/SPEC, Inc., and the American Coal Company (Pariseau et al, 1977). The Beehive Mine is located in the Wasatch Plateau coal field in central Utah near Orangeville, Utah, where mines are developed from outcrops between steep canyon walls with topographic relief of a kilometer or so (3,600 ft). Coal is found in Cretaceous sediments that dip gently to the west. Detailed geology of the Wasatch Plateau is described by Doelling (1972). Mining was done in the Blind Canyon seam. An earlier Deseret Mine worked the Hiawatha seam that is lower in the stratigraphic column by about 36 m (120 ft). Mining progress and ownership changes occurred in time with mine mergers and name changes eventually to the collective Des-Bee-Dove label. At the Beehive Mine, depth varied with topography but was approximately 360 m (1200 ft) on average; seam thickness varied from 1.5 to 6 m (5 to 20 ft) and usually required two passes of the miner. The mine was eventually closed and finally reclaimed in 2003. Semborski and Oakley (2006) present a brief history of the mine and describe the reclamation work in some detail. Figure 1 shows the surface topography in the vicinity of the mine that is in the center of the figure.

Feb 23, 2014