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By F. F. Peng, S. S. Peng, V. Z. Sun

A detailed study of ponding phenomenon relative to surface subsidence due to longwall mining was conducted for various surface stream conditions. Based on field monitoring, the stream-ponding process and three forms of stream water are described. Also discussed are the criteria of stream ponding and the influences on the ponding process by two key factors: the angle of stream flow and the change in the stream-bed gradient. A numerical (mathematical) model, which combines trend surface technique that describe the topographical features in the vicinity of a stream and the modified influence function, which represents the profile of the surface subsidence trough (or basin), is constructed to predict the formation characteristics of stream ponding in terms of location, boundary and accumulated water volume of migratory and stationary ponds produced by the stream-ponding process. Three cases are analyzed using the model to predict the interaction of the underground operations and the environmental impact due to stream ponding. The feasibility of various mitigative measures are assessed.

Jan 1, 1997

By Adam Bedell, Paul Derby, Brad Crenshaw

Modified contact grouting was introduced almost 15 years ago as a methodology combining traditional contact grouting and consolidation grouting to address groundwater infiltration into hard rock tunnels that utilize cast-in-place concrete as permanent tunnel support. This process has been used on additional tunnels (since initially presented) as a measure to mitigate both groundwater infiltration and exfiltration. During this time, self-sealing grouts have been developed and have been added to the process to further reduce groundwater infiltration that occurs through cracks and discontinuities within the concrete liner itself. This modification is presented and additional results from the grouting process are discussed.

Jun 13, 2021

By Timothy C. Richmond

The Stillwater District is located in south central Montana approximately 75 miles southwest of Billings, the state's largest city. It lies along the northeast front of the Beartooth Mountains and is within the boundaries of the Custer and Gelatin National Forests. The district contains some of the nation's most spectacular mountain scenery. Montana's highest peaks, including 12,799 foot Granite Peak, rise a few miles south of the area. Much of the district is located on a gently undulating plateau which averages 8500 ft. above sea level, broken by hills up to 10,000 feet and slashed by glacially carved canyons, some of which are more than 3,000 feet deep.(Fig. 1) Immediately to the north and east, the land falls away to the Great Plains, stretching unbroken to the Mississippi River. Two major tributaries of the Yellowstone River, the Stillwater and Boulder Rivers, traverse the area and several large streams originate in the district itself. Access to the high mountain country and the adjoining Beartooth Primitive Area is restricted to a few horse and jeep trails continuing from the terminus of improved roads in the bottom of the Stillwater and Boulder Valleys. Hunters, fishermen and cabin owners make intensive use of the area along its improved transportation routes, but hikers seldom venture more than three miles beyond the end of the roads. People from the Billings area are the most frequent visitors.

Jan 1, 1974

By John C. Gould

GENERAL DESCRIPTION The Climax mine is located 161 km (100 miles) southwest of Denver on Fremont Pass astride the Con¬tinental Divide. Climax employs 2800 people to pro¬duce 42 670 t/d (47,000 stpd) of molybdenum ore. The Storke level, the main underground level, produces 19 970 t/d (22,000 stpd); the 600 level, the lowest ac¬tive underground area, produces 7260 t/d (8000 stpd); and the open pit presently produces 15 430 t/d (17,000 stpd), Fig. 1. A panel caving method is possible because of the favorable geology and geometry of the Climax ore body. Geology The Climax deposit is composed of three separate ore bodies formed in a massive Tertiary stockwork which penetrates Precambrian granites and schists. The ore bodies are elliptical in plan with overall dimensions of 914 x 1219 m (3000 x 4000 ft). In section the ore bodies are arcuate with an overall height of 457 m (1500 ft), although the depth is not firmly ascertained. Ore grade decreases rapidly into a highly siliceous cen¬tral core and more gradually toward the outer bounda¬ries of the deposit. The mineralization is relatively continuous in the ore zone and contains few dilution-causing waste inclusions. Molybdenite is contained in pre-ore fractures which were largely recemented during the three mineralization pulses. Postore fractures, with a spacing of a few inches to several meters (feet), render the deposit amenable to caving when it is undercut. The peripheral rock caves similarly to the ore, but the central core is competent and is difficult to cave. Caving Feasibility Successful caving action requires an undercut area of approximately 122 by 122 m (400 by 400 ft). When the undercut area exceeds this minimum distance, the arching effect is lost, and the ore column collapses. Ore extensions from the main cave area less than 122 m (400 ft) wide usually cannot be caved. Waste or low¬grade areas within the deposit can be left if they are large enough to carry weight around openings passing through them. Experience indicates that these areas should be over 30 m (100 ft) in length and width. Smaller unprofitable units of waste, such as postore dikes, are mined to avoid weight problems and result in ore dilution. Successful caving and ore recovery are dependent upon timely ore removal from the undercut zone because columns of immobile ore inhibit caving and concentrate weight onto the underlying workings. Climax experience indicates that a finger (drawpoint) spacing* averaging 10.4 m (34 ft) yields an excellent caving action and a 92.5% ore recovery at the estimated grade. An additional 15% of the ore is recovered-at a diluted grade (Fig. 2). Mine Layout The slusher drift is the primary production facility (Fig. 3). The ore is undercut and caved into the fingers,

Jan 1, 1982

By B. A. Kuyper

The Cove gold-silver deposit is located 50 km southwest of Battle Mountain, Nevada and 1.5 km northeast of the McCoy Mine. Total proven and probable reserves are 48.7 Mt (53.7 Mst) with an average grade of 1.85 g/t (0.054 oz/st) Au and 87.1 g/t (2.54 oz/st) Ag. Mineralization is hosted by Triassic carbonate and siliciclastic rocks in two separate orebodies. Oxide ore consists of disseminated gold and silver in clay-altered, manganese-flooded limestone. Sulfide ore is dominated by pyrite-sphalerite-galena veins in siliciclastic rocks and sandy dolomite. Gold and silver occur in the native state, associated with the base metal sulfides. Mineralization is interpreted to be the distal expression of a porphyry system. The McCoy gold (copper) deposit is interpreted to be the proximal expression of the same system.

Jan 1, 1991

The role of ZnSO4 in activation of sphalerite (ZnS) and deactivation of lead-activated sphalerite has been investigated. Adsorption of metallic ions at the solid-solution interface, electrokinetic results for sphalerite under different chemical conditions, and thermodynamic calculations were used to elucidate the mechanisms involved. It is shown that flotation response of sphalerite in absence of activators is rather weak and that adsorption of ethyl xanthate on the mineral mainly electrostatic in nature. Zinc sulfate is found to activate the mineral but only in a narrow acidic pH range. This is attributed to the increase of zeta potential as well as the possible increase in amount of negatively charged bulk precipitated zinc xanthate. Lead ions activate sphalerite in a wide pH range and the lead activated mineral assumes a flotation behavior similar to that of galena (PbS). However, addition of ZnSO4 depresses the lead-activated sphalerite by replacing lead ions at the mineral/solution interface.

Jan 1, 1999

By Frank F. Aplan, Edward C. Jr. Dowling, Richard R. Klimpel

Thirteen kinetic models that mathematically describe the flotation process have been statistically evaluated for the flotation of copper, lead and zinc ores. Comparisons have been made for a variety of circuits involving roughing, cleaning, scavenging and regrind followed by cleaning. Variations in collectors, frothers, depressants and activators have been considered. Based on the statistical criteria used for the evaluation, and the reagent, circuit and ore variations studied, the most reliable flotation models have been identified and subsequently used to characterize the metallurgical results.

Jan 1, 1986

By P. Rusin

Many oxide silver and molybdenum deposits remain undeveloped because chemical extraction yields poor recoveries or is environ-mentally unacceptable. Bio-reductive leaching of such ore samples at MBX resulted in high recoveries of silver and molybdenum. When baseline 3-day cyanide bottle roll tests were conducted on manganiferous oxide silver ore, 13.7% of the silver was extracted. In contrast, 86% of the silver was microbially solubilized into the organic growth medium by bio-reduction with 99.8% dissolution of manganese. A follow-up cyanide bottle roll test yielded an additional 8.5% silver recovery for a total recovery of 94.5%. Baseline 3-day acid bottle roll tests of the iron oxide molybdenum ore yielded 1.8% moly. However, bio-reduction solubilized 93.3% of the moly into the growth medium. An additional 0.3% moly was recovered during the follow-up acid bottle roll test. Microbial treatment of refractory oxide ores with bio-reductive bacteria resulted in higher recoveries of silver and molybdenum than conventional chemical leaching. The bioleaching process occurred at a near-neutral pH at ambient temperatures. The bacterial solubilization of silver and moly was achieved without the use of cyanide or sulfuric acid.

Jan 1, 1992

By George K. Martin

This paper deals primarily with roof bolting in Kentucky coal mines from January 1, 1949, through December 31, 1954, a six year period. The Consolidation Coal Co? (Ky.), a division of the Pittsburgh Consolidation Coal Co., began systemmatic roof bolting in November 1948 in Mine #204, Elkhorn #3 Seam, at Jenkins, Kentucky, After the efficiency of roof bolting had been proven by the Consolidation Coal Co., this procedure was adopted by other companies throughout the state. In December 1954, approximately 46.4 percent of Kentucky's total production of coal from underground mines was obtained from roof-bolted areas. Statistics in this report will show the progress made in roof bolting during the six years, in addition to the roof bolting being done as of December 31, 1955. Significant progress has been made in the coal mines of Kentucky in reducing the roof-fall fatality, rates, during the past several years by adopting systemmatic roof bolting. The ground work by the Consolidation Coal Co, (Ky.) in cooperation with the Federal Bureau of Mines was based upon the previous experience of the St. Joseph Lead. Cc, in its Southeastern Missouri Mines and The Tennessee Coal and Iron Division of the United States Steel Corporation. The author gratefully acknowledges the cooperation and assistance given by officials of the various mining firms using roof bolts, the Kentucky Department of Mines and Minerals, and the Federal Bureau of Mines in furnishing photographs and information.

Jan 1, 1958

By Wei Li

Carbothermic reduction kinetics of ilmenite concentrates catalyzed by sodium chloride and the microwaveabsorbing characteristics of the resulting reductive products were investigated; the reduction degree of the reaction was deduced to be . Results show that the activation energy is 112.03 kJ/ mol when NaCl is used as catalyst, lowering to 23.11 kJ/mol for the final stage activation energy using sodium silicate as a catalyst. There is a sharp change in the reduction rate constant at temperature ranges of 1,223 K - 1,273 K and 1,373 K - 1,423 K. Microwave-absorbing characteristics of reductive products were measured by the method of microwave cavity perturbation. It was found that microwave-absorbing characteristics of reductive products obtained at temperatures of 850° C, 1,100° C and 1,150° C show sharp changes. Through X-ray diffraction (XRD) characterization, it was found that the formation of Fe occurs at a temperature of 900° C during the reduction process of ilmenite concentrate. The decrease of FeTiO3 content results in the decrease of microwave-absorbing characteristics, while the increase of Fe content gives rise to the increase of microwaveabsorbing characteristics. The decreasing trend is larger than the increasing trend, which is the main reason for the sharp changes in the microwave-absorbing characteristics of reductive products at the temperature range of 850° C to 900° C. When the decreasing trend is smaller than the increasing trend, it becomes the main reason for the sharp changes in microwave-absorbing characteristics of reductive products at the temperature range of 1,100° C to 1,150° C. Kinetics results show that sodium chloride can catalyze the carbothermic reduction of ilmenite, and microwave-absorbing characteristic investigations indicate that microwave heating can be used in the carbothermic reduction of ilmenite.

By James P. Connell

The American Concrete Institute defines "shotcrete" as "mortar or concrete conveyed through a hose and pneumatically projected at high velocity unto a surface." This definition thus includes what is traditionally known as "gunite," which is a pneumatically applied mortar. In mining practice, the term shotcrete is restricted to pneumatically applied concrete, and this differentiation will be used in this paper. In 1914, following the invention of the mortar gun in 1907, the then Chief Engineer of the U.S. Bureau of Mines, George Rice, developed the guntie process for underground test work at the bureau facility at Bruceton, Pennsylvania. After World War I, gunite was used extensively in American mines and was also utilized for underground civil works such as the San Jacinto Tunnel in California. The greatest development was In Europe where, as early as 1911, gunite was successfully used as an overlay for deteriorated tunnel linings. In 1951, the Swiss firm Aliva developed a pneumatic gun capable of handling coarse aggregate, thus making possible the first use of shotcrete at the Maggia hydropower development. Intially, shotcrete was used to reduce manpower requirements for forming; and placing conventional concrete. However, by 1954 Sonderegger was reporting that the structural advantages of shotcrete were derived from its flexibility and from the fact that it could be applied almost immediately niter the opening had been made. The incorporation of wire mesh into the shotcrete led to the New Austrian Tunnel Method, or NATM. The use of shotcrete in American mines has been implemented more recently. This delay seems to be due to previously unsuccessful experiences with gunite as a structural material and to the U.S. reliance on wood or steel supports in main line haulageways. The long experience with the apparently more substantial rigid supports led mine operators to be reluctant to the new and seemingly unrealistic lighter shotcrete support.

Jan 1, 1977

By David Jurich, Ed Perko, Jacob Prezkuta

Numerous Colorado mountain tunnels that date to the late 1800s convey water to the farming and urban communities of the eastern Front Range. Repairs to these remote facilities, often located in public lands at altitudes of 11,000 feet or more, require detailed planning, close coordination with multiple agencies, and creative execution. Issues and solutions discussed include designing repairs in undocumented ground and support conditions, logistical challenges, work in a short summer construction window, stabilization of historically signicant structures, and proect delivery strategies. xamples that illustrate early contractor involvement, exibility in design, and construction solutions are presented.

Jun 23, 2024

By M. C. Rockwell, G. F. T. Lay

Promising placer gold exploration sites offshore Lunenburg County are drowned pre- and post-glacial river channels and auriferous glacial tills. Gold values up to 5.67 9/m3 have been encountered in the vicinity of the Ovens Peninsula offshore Lunenburg County. Moderate gold values associated with notable amounts of heavy minerals were reported from various other exploration sites in this area. This paper highlights the major geological and gemorphological features for placer gold depositions in southern Nova Scotia. The past to present gold exploration activities nearshore and offshore Lunenburg County are summarized and potential areas for placer gold identified.

Jan 1, 1988

By Jim Buckley, Ryan Sibley, Scott G. Giltner, Thomas Pallua, Joe Schrank, Robert Cidlik

Because of variation in rock type and site conditions, it is important to create site-specific prediction models for peak particle velocity (PPV) and understand instrumentation mounting locations to better interpret the readings provided following blasting operations. The Atlanta Airport is expanding the section of underground tunnels for its Plane Train people mover, and drill and blast operations were determined to be the suitable method of excavation for the project. Extensive work was done to begin creating prediction models and determining levels of concern based on readings from various types of instrumentation. This paper analyzes the effect of close quarters construction blast vibrations and observed frequency spectrum on existing structures with data from 22 different seismographs mounted in various locations and ground conditions.

Dec 1, 2022

By John F. Burst

For several generations now, the high alumina clayey sediments of Southeastern Alabama and Southwestern Georgia have supplied those regions with steady, mineral-based income although the impact of that income has been relatively minor until recently. Since World War II, mining activity has increased algebraically with over half of the total ore value in the Alabama area having been recovered since that time. The Georgia area production increases are even more dramatic. The trends are continuing and the next decade should see ore winning figures which will dwarf all previous production. It's time for the mining engineers to take note of this development as the mining methods, similar to the production, have developed rapidly and now offer challenges for the most competent professional. The development of mining techniques has followed a classic pattern. Beginning almost a hundred years or so ago, with the loading of weather-resistant surface boulders into mule-drawn wagons, mining methods have progressed to discovery of limited surface exposures in outcrop and eventually to stripping and development of non-obvious, subsurface deposits. Little by little, the overburden thickness of new pits has increased until, at present, pits with 100' -125' of overburden are being actively worked. Ground water problems in the Eufaula District are particularly challenging. At A. P. Green's J. W. Baker Pit, #l, in Barbour Co., Alabama, it is necessary to continually pump groundwater at the rate of about 400 gallons per minute from wells on the periphery of this large pit in order to keep the water table low enough to allow mining of the ore body.

Jan 1, 1972

By A. Ballester, F. Gonzalez, M. L. Blázquez

Pyrometallurgical process are usually used to recover valuable metals from metal sulphide concentrates. However, their use is diminishing as the cost of energy rises and pollution controls become strictes. An alternative method of treatment sulphides could be bacterial leaching due its simplicity and negligible contamination (1-2). This process is presently used commercially to re cover metals such as Cu and U from low grade ore concentrates. In spite of numerous researchs during recent years (3-5) there exists very little kinetic data concerning the speed of bioleaching process. The kinetic analysis of bacterial activity is related with the metabolism and growth of microox ganisms . This fundamental information permits ma- king the best utilization of bacterial oxidation and to suggest techniques which might increase the production of the products desired. However, bio- kinetic models are especially complicated due to the existence of many metabolic routes and parallel reactions which are important for the life of the bacteria. Microbiological oxidation of a mineral substrate is influenced by its own inicial concentration: This influence can be determined by means of a kinetic study. In a medium with sufficient concentration of nutrients (nitrogen, phosphorous and potassium) and an adequate supply of 0, and CO2, as the only & L source of carbon for the biochemical synthesis, the substrate concentration would remain the only limitation in the rate of leaching. In this case the Michaelis-Menten model could be applied (6). The model is based on an association of the enzyme (El with the substrate (S) with consequent decomposition of the latter into enzyme and products [ ] The rate of dissolution is defined by the equation : [ ] Were V is the rate of metal extraction (mg 1-1 1 h-1 ) ; S is the pulp density Mn is the maximum rate for metal extraction (mg 1-1 h-1) and K is the constant of Michaelis (concentration of substrate that yields Vm/2). This method is applicable only when the rate of bacterial growth is similar to the rate of metal extraction. It would therefore be sufficient to control the concentration of metal in the medium over the period of time. In the present work a systematic study of the kinetics of ZnS and CuFeS bioleaching in sphalerite and complex ore concengrates was carried out. The rate of dissolution of the Zn and Cu as function of the pulp density and temperature was determined. However, most oxidations of sulphide dissolution take place with a very slow kinetic; but, this can be accelerated considerably by the addition to the solution of suitable catalytic ions, as was Suggested many years ago by Bjorling (7). Such ions can exercise an important influence on the rate of the oxidation-reduction reactions, both homogenous and heterogenous, which take place during the leaching of sulphides; they also affect the nature of the reaction products. The action of catalytic ions has been fully developed in aqueous systems, but in the absence of bacteria (8 - 11) although the actual machanisms is not totally known. The mechanisms proposed as hypotheses in the literature (8) indicate that, in the case of ZnS, the catalyst ion act through an electrochemical mechanism according to the reactions: [ ]

Jan 1, 1989

By Jeffrey L. Zelms

There is no known, practical substitute for lead in the automobiles, communications systems, medical equipment and computers that Americans use every day. However, there are many who say lead should be stopped at its source -- banned. As America's largest lead producer, The Doe Run Company has ralized that it must do more than mine and reclaim lead efficiently and safely. It must also earn the public's consent to operate if it is to continue to be a viable business. LEAD - THE BRILLIANT PERFORMER: REFURBISHING AN IMAGE It's been an embarrassingly long time since I was a college student. However, I remember there was no course at the University of Missouri's School of Mines and Metallurgy that had anything to do with the public relations aspects of mining or, put another way, the politicization of mining. It's been an embarrassingly long time since I was a college student. However, I remember there was no course at the University of Missouri's School of Mines and Metallurgy that had anything to do with the public relations aspects of mining or, put another way, the politicization of mining. I haven’t perused the course catalog for Penn State’s College of Earth and Minerals Sciences. But I strongly suspect I wouldn’t find such a course there today, either. A statement by the chairman of one of the country’s largest chemical companies leads to the point I want to make. He described his business this way. He said, “We’re a public affairs company that just happens to produce and market chemicals.” Like chemicals, minerals and mining are politicized today. To the extent that we don’t understand that reality, we don’t understand that reality – and act on it – we’re less likely to survive in this business. Some of you may well be saying to yourselves, “This guy Zelms is an alarmist.” That’s fair enough. Because it is absolutely true that there’s n o known, practical substitute for lead today. And it’s also absolutely true that, knowingly or not, Americans use lead everyday. It’s in our automobile batteries. It’s an integral part of communications systems. High tech (and low tech) medical equipment contains lead. And lead is an essential component of computer and TV screens. But even with all these uses, lead has a negative image today. An image so negative that its very existence is threatened. If you doubt that, consider these two statements made in 1989. Statement one. “It is probably reasonable to argue that exposure is the single most important and critical environmental health problem in the U.S., and possibly also the world…” Statement number two. “Many of the uses of lead should be terminated. We need to go back to the ultimate source: that is, taking lead out of the ground and putting it into the product stream and we need to turn it off at the ultimate source. Not the approximate lead in gasoline, or lead in air, or lead in food. Go right back to the source and start cranking it down." (End quote.) Those are what I call strong statements. And they weren’t made by some celebrity spokesperson for the environment like Meryl Streep. Both these statements were made by Dr. Ellen Silbergeld, whose long list of professional and academic credentials includes: o Adjunct professor and research scientist at the University of Maryland Medical School and Johns Hopkins: o Chief toxic scientist and director of the Toxic Chemicals Program of the Environmental Defense fund; o and President of the Society for Occupational and Environmental Health. If Dr. Silbergeld were the only person making these kinds of statements, it would be one thing. But she’s not a voice in the wilderness, by any means. Also for those of you who say, well since there’s no known substitute for lead, how on earth could it be banned. I refer you to a number of bills before Congress that would permit the EPA to ban any product if it is determined that its

Jan 1, 1992

By B. Pesic, J. E. Wey

Introduction One important class of manganiferrous ores is manganiferrous-silver ores. They occur in the oxidized portions of the silver deposits of the western United States. Silver is often associated with manganese oxides, which in some ore deposits are dispersed through calcite, causing the black color of the host rock, known as black calcite. Black calcites can occur in carbonate rocks (0.3 to 50 kg Ag/t) and in volcanic rocks (less than 30 g Ag/t). Silver mineralization associated with manganese oxides and black calcites can occur in veins (Hewett, 1968) or as disseminations (Graybeal, 1981). In the US, silver-bearing manganese veins are located in a broad arc that extends from southern Colorado to southwest New Mexico, southern Arizona, and southeast Califor¬nia (Hewett, 1964). Areas of disseminated silver-manganese mineralization include the Creede and Silver Cliff districts of Colorado and the Tombstone and Hardshell districts of Arizona (Graybeal, 1981). These deposits are also characterized by significant amounts of silver halides - cerargyrite (AgCl), bromargyrite (AgBr), and iodargyrite (AgI). Black calcites are also common in these deposits. Oxidized silver ores containing the higher oxides of manganese are generally refractory to hydrometallurgical methods of treatment. In the past when these ores could not be smelted, they were treated generally by cyanidation at very low efficiency. The US Bureau of Mines (USBM) studied the problem of treating silver-manganese ores in the early 1920s (Clevenger and Caron, 1925). It was found that the refractory silver in the original ore was insoluble in all the common solvents for metallic silver and its salts. The conclusion was that to obtain the highest recovery of silver, all the manganese had to be dissolved or the higher oxides of manganese reduced to manganous oxide. More recent results from treating refractory silver¬manganese ores were given by USBM (Scheiner et al., 1973). The silver ores from Candeleria District, NV, and Round Mountain District, CO, were investigated. Electrooxidation experiments recovered only 34% silver with minor amounts of manganese dissolved. Sulfurous acid pretreatment followed by cyanidation revealed that silver extracted was proportional to the amount of SO2 used. A similar approach, using sulfurous acid pretreatment followed by cyanidation, was also proposed by Rhoades et al. (1984). Hazen Research Inc. performed extensive testing on silver and manganese dissolutions from Ag-Mn ores obtained from the Candeleria and Round Mountain ore deposits. The methods examined were direct cyanidation, pretreatment with sulfurous acid followed by cyanidation, malonitrile leach, and leaching with ammonium hydroxide-sodium thiosulfate under slight oxygen pressure. The results were not satisfactory. The importance of the vast reserves of Ag-Mn ores and the lack of an efficient method to recover these metals warranted a search for new technologies. One novel method for extraction of these metals is treatment of Ag-Mn ores with acidified thiourea solutions. Preliminary results of the leaching of silver and manganese from Ag-Mn ores were very encouraging (Pesic, 1984a) ; thus, it was decided to examine the new lixiviant in more detail. Experimental Ore from the Round Mountain District was studied. It was crushed, ground, and dry sieved into monosized fractions in the range of 16 to +400 mesh. The ore composition was about 90 g Ag/t and 3% Mn, depending slightly on size. The leaching experiments were performed in apparatus described elsewhere (Pesic, 1982 and 1984b). All experiments were performed at constant temperature conditions. The leaching residues were analyzed for silver and manganese. Atomic adsorption was used to analyze the solution samples and fire assaying to analyze the leaching residues (for silver). The standard experimental conditions are given in

Jan 1, 1987

By F. Calizaya

A booster fan is an underground fan installed in series with a main surface fan and used to boost the air pressure of the ventilation air passing through it. To accomplish this objective, the fan is installed in a permanent stopping and equipped with airlock doors, a monitoring system, and interlocking devices between main and booster fan controls. The stopping and doors are used to prevent flow recirculation, and the monitors to ensure safe operation of the fan. A booster fan, properly sized and sited, can be used to create safe work conditions and allow the extraction of minerals from areas that would otherwise be uneconomic to mine. In deep and large mines with heavy emissions of air contaminants, the required quantities of air can only be supplied by using high pressure fans. These fans will inevitably induce significant losses of fresh airflow through the stoppings and doors. For well defined ventilation circuits, booster fans can be used to decrease the main fan pressures and reduce the leakage flows. However, this will require a good understanding of the correct ventilation practice, from planning to operation and maintenance of booster fans. The objective of this study is to investigate the conditions under which booster fans can be used safely and efficiently in underground coal mines. Specifically, the study is directed at (1) collecting reliable information on airway resistances and flow requirements from two large U.S coal mines, (2) collecting fan performance data from one or more existing coal mine where booster fans are used regularly, (3) monitoring the performance of booster fans in a laboratory model and an experimental mine, (4) developing a booster fan selection method to assist the ventilation engineer at the planning stage, and (5) training six M.S. or Ph.D. graduate students in advanced mine ventilation.

Jan 1, 2010

By William J. Orlandi

The intent and scope of this paper is to present to you, as concisely as possible, the problems and requirements -- and what we consider advantages -- of all-belt haulage in a modern underground coal mine. Mine No, 10, at Pawnee, Illinois, was opened in 1951; consequently, all the planning and consideration given to haulage selection was based on information then available and on Peabody Coal Company? s experience to that date,

Jan 1, 1961