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By Rebecca S. Stanevich

BACKGROUND Diesel exhaust is an animal carcinogen, although evidence of the carcinogenicity in humans is "limited". (World Health Org. , 1989) Of the eight cohort studies in the 19808, five found an increased risk for lung cancer among workers who may have been exposed to diesel exhaust (RR from 1.3-1.5, SMR from 101-132). (Howe, et al., 1983) Only two studies accounted for smoking indirectly. Of the ten case-control studies in the 1980's, eight reported increased risk of lung cancer among those populations purportedly exposed to diesel exhaust. (Benhamou, et al. , 1988) All but one of these adjusted for smoking and other occupational exposures. The odds ratios ranged from 1.2 to 2.1. In two of these studies, miners experienced a two to three fold risk. (Benhamou, et al., 1988) Bladder cancer has also been linked to diesel exhaust in cohort and case-control studies. Excesses of approximately 50% were observed among truck drivers in studies by NCI. (Hoar, et al., 1985) In the National Bladder Cancer Study, risks for truck drivers rose with duration of employment. A study by NIOSH in Ohio also found an excess of bladder cancer among truck drivers, particularly among those with 20 or more years of employment. (Steenland, et al, 1987) Despite the large number of studies in which the relation between diesel exhaust exposure and lung cancer has been examined, exposure to diesel exhaust has been quantitatively estimated only in the studies of railroad workers and truck drivers. (Woskie, et al., 1988) The excess lung cancer risk experienced by workers in these two occupational groups was modest, ranging from 40 to 90% for those with long-term employment. However, diesel exhaust exposure among railroad workers and truck drivers is lower than that seen among miners. Several markers of diesel exhaust have been utilized in these studies. Diesel exhaust is a complex mixture of particulates, vapors and gases. One group of these gases, the nitrogen oxides, react with polynuclear aromatic hydrocarbons, forming mutagenic and possible carcinogenic nitrated derivatives. (World Health Organization, 1989) For this reason, and because it is easy to measure and analyze, NO, was frequently used as a marker of diesel exhaust exposure. As part of the Garshick (Garshick, et al., 1988) study of railroad workers, Woskie measured NO, exposures of 477 railroad workers. (Woskie, et al., 1988) Geometric mean exposures of 13 job groups ranged from 12 to 80 ppb. In a New Mexico potash mine, (Attfield, et al. , 1982) exposures of from 100 to 3300 ppb nitrogen dioxide

Jan 1, 1992

By Hou Xilun

Three production methods of rapid cold bonding and low temperature bonding pellets using sponge iron powder as a binder have been successfully developed. These methods differ from ordinary bonding method by no addition of salt and other catalyzers, no corrosion of equipment and no pollution of environment. Mechanism of pellet bonding is studied. Experiment shows that these pellets have good metallurgical properties. A semi-industrial test has proven the laboratory results, with the production of metallic pellets continuous and stable. These methods are substituted for traditional high temperature firing of oxidized pellets in direct reduction. As a result, the plant for oxidized pellets can be saved and substituted for grate in the grate-kiln system. Thus, 20% of the investment could be saved. Production cost may also be decreased. The production of cold bonding pellets does not need additional area.

Jan 1, 1980

By C. Y. Kao, Roger Y. Cheng, C. S. Hsieh

The mushroom-shaped Minghu power cavern located in central Taiwan is 21.2 m (W) by 40.5 m (H) by 127.2 m (L) and is designed to house 4 units of power generating-pumping equipment with a total capacity of 1,000 MW. This paper presents an introduction to the geological conditions at the cavern site; the rock mechanical tests undertaken; the design approach adopted; the construction method and sequence followed; and the instrumentation provided in the roof arch to monitor the behavior of the surrounding rocks. The measured data collected from the embedded instruments will be compared with those obtained from theoretical analyses and presented in this paper. Several technical problems encountered during the construction stage are covered and the solutions of these problems are also described therein.

Jan 1, 1983

By J. J. Kellar

Researchers have long speculated regarding the adsorption state of collectors on mineral surfaces. Only recently have analytical techniques become available which allow direct in-situ analysis of adsorbed layers. Fourier transform infrared spectroscopy coupled with internal reflection spectroscopy (FT-IRJIRS) with reactive internal reflection elements allows for unobtrusive investigation of the adsorbed layer (Harrick, 1979). This technique has been used both for the in-situ identification of adsorbed species and for the direct calculation of collector adsorption density in real time from infrared spectral data (Miller and Kellar, 1988). The reactive mineral IRE serves both to internally reflect the infrared light and to act as a substrate at which collector adsorption can be monitored. Shown in Figure 1 is a schematic of light being internally reflected in an IRE. As the light is totally reflected at the interface, an evanescent wave propagates a short distance (typically a few microns) away from the IRE, and sampling of the interfacial region occurs. Because of multiple internal reflections, great sensitivity can be obtained. Flotation systems for which this method has been demonstrated include CaF2/oleate, Al2O3/ dodecyl sulfate, CaCO3/oleate, ZnS/xanthate, and KCl/octylamine (Miller and Kellar, 1988; Kellar et al., 1989, 1990; Miller et al., 1990).

Jan 1, 1992

By Carl F. Austin

The subject of strata control in mining can be approached from both static or loading concepts or from dynamic or impulsive loading concepts. The fracture process itself appears to be primarily a dynamic process as is the gross creation of fractures through the use of impact, stress wave passage or in more general terms, the use of explosives. This paper presents experimental results which indicate that the understanding of the fracture behavior of rock that has been, established in the open literature is not always appropriate. In particular, the results of this experimental program have shown very interesting differences between the formation of fractures in rock and the formation of fractures in other materials such as metals and plastics which are often used as models for rock behavior studies Fracture patterns and causes of dynamic fracturing in various rock and artificial materials are presented.

Jan 1, 1965

By D. W. Olson

Estimated world production of natural and synthetic industrial diamond was about 630 million carats in 2004. Natural industrial diamond deposits have been found in more than 35 countries, and synthetic industrial diamond is produced in at least 10 countries. About 80 percent of the global output was produced in Ireland, Japan, Russia, South Africa and the United States. Russia and the United States are the world’s leading producers of synthetic industrial diamond. In 2004, the two U.S. synthetic producers, one in Pennsylvania and the other in Ohio, had an estimated output of 250million carats. Also in 2004, nine U.S. firms manufactured polycrystalline diamond (PCD) from synthetic diamond grit and powder.

Jan 1, 2005

By Charles T. Steuart

The Arkansas Novaculite of Devonian and Mississippian age is the most distinctive formation in the central Ouachita Mountains of Arkansas from the standpoint of both topography and lithology. The formation typically forms precipitous, narrow ridges (hogbacks) which reflect the steepness of dip and the resistance and thickness of the rock units. The Arkansas Novaculite varies from less than 200 feet thick in the north to locally over 800 feet thick in the south and outcrops over an east-west distance of 360 km (200 miles) in the Ouachita Mountains of Arkansas and Oklahoma. Most of the rocks of the formation are highly siliceous with novaculite predominating, and lesser quantities of chert, siliceous shale, conglomerate and rarely sandstone. Novaculite is commonly defined as a homogeneous mostly white rock, translucent on thin edges with a dull to waxy luster and composed almost entirely of microcrystalline quartz. The word novaculite comes from the Latin word novacula, meaning razor hone. This term was first used by Richard Kirwan in his mineralogy text of 1784. The origin of novaculite remains controversial but we believe it was a primary silica derived mostly from the alteration of submarine volcanic-rich materials, with numerous fine biogenic components and some minor clastics (derived mostly from foreland facies via turbidity currents) and deposited as an amorphous siliceous ooze in the deep Ouachita trough. It was subsequently converted to microcrystalline quartz during diagenesis by the compaction of the overlying rocks and the intense Late Paleozoic Ouachita Mountain tectonism. In the central and southern portions of the region three divisions of the formation have been defined: a Lower Division predominantly of light-colored novaculite; a Middle Division of interbedded dark chert and shale; and an Upper Division of massive often calcareous novaculite. In the northern exposures the formation is thinner and contains more black chert and shale, chert-shale conglom¬erate, sandstone and less novaculite. The massive novaculite of the Upper and Lower Divisions is a source of high purity silica (99+%). Indians were the first to use novaculite. They made their various tools and hunting implements from the weathered broken rock until they learned the quarrying techniques. The first white men in the area recognized the use of novaculite for sharpening their tools and knives: previously whetstones were obtained in small quantities from Europe. To this day whetstone is quarried mostly in areas which the Indians and possibly the Spanish previously worked. Some of the current mining practices have changed very little from those of the early quarryman. In areas where the novaculite of the Upper Division is poorly cemented, this friable tripolitic material has found applications in such uses as an abrasive, as a filler or extender in paints, plastics and other purposes. Some of the dense novaculite is suitable as a filler in fire bricks and also in plastics. Because some of it has the tendency to decrepitate when heated not all novaculite can be used for these applications. Several quarry operators are crushing novaculite for road, concrete, and other aggregate. This use was formerly rather limited due to the abrasiveness of the novaculite on crushing and screening equipment. Further potential uses of novaculite are speculative but include application of high purity silica in the production of silicon metal for solar cells, seed or "growing", and fusing quartz for electronics.

Jan 1, 1985

By T. J. McKeon

Gravity separators such as spirals are commonly used in multistage cleaning and scavenging circuits to improve the quality and recovery of concentrates produced in the industrial minerals industry. Unfortunately, field surveys suggest that many industrial operations are poorly configured in terms of equipment layout. This shortcoming can often be attributed to a failure by engineers to make use of fundamental process engineering tools for circuit design. One of the most important of these is linear circuit analysis. This powerful tool makes it possible to mathematically compare the relative efficiency of circuit configurations in advance of experimental testing. This article provides a basic review of the linear circuit analysis concept and discusses some of the key insights it provides for the layout of multistage circuits. An industrial case study is provided to show the tremendous impact that this process engineering tool can have on the design of multistage spiral circuits in a heavy mineral wet plant.

Feb 1, 2012

By D. Hodouin

The improvement of mineral processing data using material balance computer programs is nowadays a current practice in many plants, engineering companies or research centers. It now becomes more obvious that such programs should integrate new features such as the preprocessing of data, the estimation of less accessible process variables and an in-depth interpretation of: the computed results. A few solutions to these new problems are already available. The feasibility of a mass balance computation for instance can be examined by analyzing the degree of redundancy of the measurements prior to any data adjustment. New variables such as chemical analyses in particle size intervals or liquid phase composition can be included in a set of measurements. Finally, a sensitivity analysis can be used to analyze the reliability of the results, to detect eventual outliers or to redesign a sampling scheme. Some illustrations of these new developments are presented.

Jan 1, 1989

By Larry D. Wayland

Almost 100 sedimentation ponds were conceptually designed for a large surface mining study area in northeast Texas. An approximate procedure was developed to economically estimate construction quantities in order to predict surface water control costs. This procedure utilized site-specific empirical relationships developed from detailed analyses on a representative number of proposed sedimentation ponds. Use of these equations provided earthwork volumes, and spillway pipe lengths. The procedure developed for this study is presented along with the results of a verification analysis.

Jan 1, 1983

By William H. Langer

Nearly every community in the United States is dependent on aggregate (sand, gravel, and crushed stone) resources to build and maintain its infrastructure. Unfortunately, developing aggregate resources to meet societal needs causes environmental impacts. Most environmental impacts associated with aggregate mining are benign. Extracting aggregate seldom produces acid mine drainage or other toxic effects commonly associated with mining of metallic or energy resources. The most obvious environmental impact of aggregate mining is the conversion of land use, most likely from undeveloped or agricultural land use, to a hole in the ground. This major impact is accompanied by loss of habitat, noise, dust, blasting effects, erosion, sedimentation, and changes to the visual scene. Some of the impacts are short-lived, and most are easy to predict and easy to observe. Most impacts can be controlled, mitigated, or kept at tolerable levels and can be restricted to the immediate vicinity of the aggregate operation by employing responsible operating practices and available technology. The intensity of environmental impacts generated as a result of mining are determined in large part by the geologic characteristics of aggregate deposits (geomorphology, geometry, and physical and chemical properties). Mining deposits that are too thin, or contain too much unsuitable material, results in the generation of excessively large mined areas and large amounts of waste material. Mining aggregate can lead to serious environmental impacts in some situations. Some geologic environments such as active stream channels, slide-prone areas, and karst terrain are dynamic and respond rapidly to outside stimuli including aggregate mining. Some geomorphic areas and (or) ecosystems underlain with aggregate serve as habitat for rare or endangered species. Similarly, some geomorphic features are themselves rare examples of geologic phenomena or processes. Mining aggregate might be acceptable in some of these areas, but should be conducted only after careful consideration, and then only with extreme prudence. Failure to do so can lead to serious, long-lasting, and irreversible environmental consequences, either in the vicinity of the site or at locations distant from the site. Environmental impacts caused by irresponsible aggregate mining can compromise mining in an entire region.

Jan 1, 2001

By William Gleason

"In 2008, the world quietly hit a milestone that did not receive much fanfare or publicity, but it hit one that marked a turning point in the history of mankind and the way the planet is and will be inhabited in the future. It was in 2008 that, for the first time, more than half of the world’s population, an estimated 3.3 billion people, resided in urban areas. The world’s population had moved from being a majority of agricultural and rural society to an urban society. Andrew Whalley, deputy chairman for Grimshaw Architects, said this change in where and how people live will continue to increase urban populations and, by 2050, it is estimated that more than 6.4 billion people will live in urban areas. To meet these needs, Whalley, speaking during the keynote session of the 2105 Cutting Edge conference in Denver, CO, said future cities will have to be reimagined and redesigned to be more efficient. A large part of that design will be in the infrastructure of those cities.At the Fourth Annual Cutting Edge Conference, Sept. 21-23, much of the discussion was around how the tunneling and underground construction industries improve cities in a number of ways, including societal, environmental and in overall efficiency. There was talk, not just about the improvements that society enjoys at the completion of such projects, but also about the challenges faced by the owner and contractor in the construction of such projects.The conference, titled Urban Tunneling, brought together some of the top minds in the industry to not only discuss the issues faced today, but also those that will shape the industry in the future.For his part, Whalley spoke about a number of projects around the world and how they have impacted society in ways beyond simply providing a better means for transportation of people or water. Notably, he spoke about the Crossrails project in London.London is a city of 8.6 million people and a history that dates back nearly 2,000 years. It is a great example of the challenges the industry faces in bringing modern efficiencies to an established city.Running more than 100 km (62 miles) with more than 42 km (26 miles) of tunnels passing through 40 stations, including 10 new stations, the project is the largest in Europe and will transform the way people move about the city."

Jan 1, 2015

By Allan M. Hale

The central Florida phosphate industry is not a recent development. The first phosphate mining occurred in approximately 1888 (1). Many of the original mining companies were "wildcat" operations operated with rapid phosphate extraction as the sole purpose and no long-term commitment to development. Many of the early pioneers were ill-equipped to mine phosphate at either a practical or economical level; as a result many of these early companies "folded" after only a brief period of operation. However, as these early companies went out of business, several large companies developed, expanded their mining territories bought up the folding companies and by 1903 (little more than 10 years after the first mines were started), approximately 37 of the original 60 mines were control- led by three major companies (1). In the early period, mining reclamation was nonexistent. The mined out areas were left to revegetate and reclaim "naturally" over the period of many years. Reclamation practices were only started relatively recently and the various reclamation techniques developed and used in the past have continued to be employed with varying degrees of success through the present time. The reclamation techniques used in the past and currently include land and lakes restoration, sand tailing reclamation, slime ponds reclamation and overburden fill.

Jan 1, 1980

By Osvaldo A. Bascur, J. P. Kennedy

Companies have installed powerful desktops for their personnel and instrumentation and control systems in their plants. These desktops are, in many cases, connected to a company intranet. Still, process engineers have to obtain their data manually. Engineers use process calculations from manually calculated averages from the plant; field operators collect equipment data on log sheets; and maintenance engineers collect critical information on log sheets. All of this information resides in individual machines. What are the strategic tools that will enable collaboration between them? How can operators, engineers, and managers access plant information to proactively increase their effectiveness in process troubleshooting, plant debottleneclung, aligning with business strategic and customer demand, satisfying environmental and safety regulations, developing capital projects, and implementing control strategies? A nonintrusive environment at the desktop is required to provide the process information to these workers. How can value be added to MS Windows technologies with the legacy systems at a minimum cost? There is no straight answer; however, there is a proven framework to leverage the large investments in new technologies. Objects and components are changing the way everyone relates to their computer and networks. Three examples will be described to demonstrate paradigm change. Today, process engineers can access data at the required level of detail for analysis of critical process variables at their desk or remotely. 1. Process Troubleshooting and Analysis: The engineer can develop an inferential calculation, trigger a process advisor to deter- mine the behavior of the units for the last day, and get the population of a set of batches (heats, blocks, rolls, sheets, etc). 2. Process Control and Optimization: The engineer can connect to a process simulator at steady state or a dynamic simulator of the process to evaluate new control strategies or process unit line-ups and use the process simulator as a process observer for fault diagnosis. 3. Collaboration with Accounting and Maintenance: The engineer can review reconciled data and the process mass balances, suggest maintenance cleaning or recalibration of flowmeters, and evaluate key control performance of all advanced controls.

Jan 1, 1999

By J. L. Schroder, William J. Halvorsen, Wiliam W. Lyons, Kent C. Ware, Sheridan A. Glen, Donald C. Simpsom

The prospects for near-term growth in coal demand are exceptional: the federal government recently targeted 141 oil- and gas-fired generating units for mandatory conversion to coal; coal-to-synfuel developments are proceeding at a steady clip, with construction of a $1.2 billion gasification plant to begin this year in Beulah, ND; uncertainty over nuclear power and stratospheric oil prices enhance the steam coal market; the export market is ripening; and an influential new political force (the Senate Coal Caucus and Congressional Coal Group) is flexing its muscles on Capitol Hill. But the rosy picture is muddled by signals, often conflicting, sent out by federal agencies. Although EPA can be credited with relaxing its grip on the Clean Air Act, its sulfur dioxide control strategy is still often at odds with the Administration's call for domestic energy (coal) development. B. R. Brown, president of Consolidation Coal Co., sums up the situation: "Every mule is pulling in a different direction." Often in the midst of the fray is the small operator who has been hardest hit by the stagnation of coal markets. Layoffs, shortened work weeks, and mine closures were rampant in the eastern and midwestern coal fields, even among large producers. The longstanding boom in western coal was tempered during 1979 by a noticeable slowdown in announcements of new mine construction. The prognosis: Eastern coal will remain in the doldrums for quite a while to come as it works off some 90 Mt of overcapacity. Midwestern coal will fare no better due to the regulatory-influenced appetite of midwestern utilities for low-sulfur western coal. This displacement should ease, though, as new power plants equipped to burn high-sulfur coal come on line in the years ahead. In the West, the National Coal Association projects production to increase a healthy- 10% this year, although mine-to-market transportation looms as the single largest stumbling block to marketing efforts. Fatalities Up 40% in 1979 The National Coal Association estimated total coal production in 1979 at 671 Mt, an increase of 13% over 1978. Of this total, the East and Mid-west accounted for 476 Mt (71%) and the West produced 195 Mt (29%). With the consistent rise in western production playing against flat outputs in the East and Midwest, underground mining's share of total production continues to slip and is expected to account for only 38-39% in 1980. Incidence of deaths and injuries at US coal mines soared in 1979 over 1978 rates. MSHA figures (still subject to final adjustments) reveal a death rate of 0.07 per 200 000 man-hours, up 40% over 1978's 0.05 figure. MSHA chief Bob Lagather attributed the death incidence to the large number of new coal mines put on line in 1978, which he estimated at between 350 and 400. Nonfatal injuries rose to 8.48 per 200 000 man-hours, up about 15% from a 1978 rate of 7.35. In absolute numbers, MSHA counted 144 fatalities and 18 111 lost-day injuries during the 1979 calendar year. The 144 coal mining deaths in 1979 is the highest number of coal fatalities at US mines since 1975.

Jan 5, 1980

By J. R. Palmes

Flocculation of coal fines with varying degrees of wettability was studied under well defined hydrodynamic conditions. In this study, three coal samples were tested with three different flocculant types. The results revealed that flocculation depends strongly on both the coal surface properties and the type of flocculant used. A hydrophobic flocculant was found to be effective for hydrophobic and slightly oxidized coal, a semihydrophobic flocculant was found to flocculate, to different extents, all of the samples except the oxidized cool, and polyacrylimide flocculated all of the coals, which is a clear indication of its insensitivity towards coal wettability.

Jan 1, 1994

By Ahmet Unal

Inexpensive and effective means of delivering courses to mining engineers who live at remote and scattered locations remains to be a challenging issue. Computer-based instructorless but interactive multimedia delivery is a good substitute to traditional short courses and one-way broadcasts. Such a system, enhanced with a wide area network, is an inexpensive alternative to two-way broadcasts and even to a traditional university. Course material can either be delivered on compact disks (CDs) or on-line from the host servers over the phone lines using a personal computer and a modem. Although technically not feasible using ordinary telephone service lines at the present time without further modification, advances in this field indicate that this up and coming medium may dominate the competition in the future. This paper investigates the present and the future of this technology and discusses the experiences gained in creating and disseminating a prototype multimedia CD which was created at the Rock Mechanics and Explosives Research Institute of the University of Missouri-Rolla to teach a portion of a course in Ground Control. The hardware and software used in creating the audio, 3-0 graphics, animation dips, video clips, and movies are listed. The structure of the program and the way how interactivity was achieved is explained in detail.

Jan 1, 1996

By E. M. Frizzell

This paper addresses the use of the microcomputer programs BACKONE and BACKWEDG for an estimation of rock mass strength characteristics by back analysis of plane and wedge failures. The artificial support requirements are also determined by the programs PLANE2, BOLTPAT, and BOLTWEDG in terms of rock anchor installation angles, tensions, and installation patterns. These programs have been combined into a package called BACKPACK, which can be applied in open pit mines where some failures have already occurred.

Jan 1, 1988

By A. E. Michon

My comments today are directed toward western coal and its impact on Burlington Northern. I will be discussing three major topics. These are: location and extent of mining activities, the flows of this coal traffic into the various market territories, and finally the interaction of this western coal with coals found in the balance of the United States. When we at BN speak of western coal, we refer to those substantial deposits lying in southeastern Montana and north-eastern Wyoming. This territory covers many different coal formations. For the sake of simplicity, I will be referring to this general area as the Powder River Basin (or the "western" coal fields). This slide highlights the area overlayed by a map of the BN rail system. The U.S. Bureau of Mines estimates the demonstrated reserve base of Montana and Wyoming to be approximately 176 billion tons. Of this figure, about 73 billion tons is minable by surface methods. This is roughly 72% of the total strippable reserves in the western united states, BN does not have sole access to this coal for there are deposits in southern Wyoming near the union pacific railroad. I will say more about this later.

Jan 1, 1978

By Donald C. Trueblood

Since the Surface Mining Control and Reclamation Act (SMCRA) was passed in 1977, coal mine reclamation has been restricted from utilizing bluff-1ike features in permanent reclamation. This restriction is based on those provisions of SMCRA which require the elimination of all highwalls. In 1987, the Wyoming Mi ni ng Association began an effort to acquire the ability for coal mines to utilize bluffs in permanent reclamation for the purpose of enhancing the post-mining land use. The regulatory reform approach being uti1ized includes formation of a work group with members from industry, government, agriculture, and environmental organizations to prepare a proposal. Advantages of this approach are discussed.

Jan 1, 1989