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By Kenneth R. Miller

ThunderBasin Coal Co. has two mines located in the southern portion of Wyoming's Powder River Basin - the Black Thunder Mine and the Coal Creek Mine. Both are located 60 to 90 kin (37 to 55 miles) southeast of Gillette. The mines are principally located on federal coal leases acquired in the late-1960s. Development plans for the Black Thunder Mine focused on dragline stripping. Environmental considerations, however, made truck-shovel stripping the method of choice when the mine opened in 1976. In 1981, the Coal Creek Mine opened as the first dragline mine in the Gillette area of the Powder River Basin. The regional terrain is flat-lyimg with occasional clinker-capped hills. The mines are located on the Wasatch and Fort Union Formation contact. The coals are Paleocene in age. The deposits are structurally simple, dipping gently to the west. The seams are thick and are classified as sub-bituminous-C. The Black Thunder Mine, with its 21-m (70-ft) 'hick seam, is strategically located in the center of the highest heat value mining area of the southern Powder River Basin.

Jan 1, 1993

By G. J. Jansen

Introduction The usefulness of microscopes in exploration and ore dressing, problems has been documented for the older generation of mining industry personnel in such publications as Schneiderhohn and Ramdohr (1931). A more recent publication that examines the subject is Process Mineralogy, a conference proceedings of The Metallurgical Society (TMS, 1981). However, it is worthwhile to review some of the principles and advantages of microscopic examination of rocks, ores, and mill products. Transmitted light Microscopists can look at materials in transmitted or reflected light. Studying transmitted light is what is usually meant by petrography. In this method, the light passes through the specimen. The upper polarizing filter can be moved in (crossed nicols) or out (open nicols) of the light path. The specimen can be a thin section, a slice of rock mounted on a glass slide and ground to 30 µm (>400 mesh). Or, it can be a sample of rock or ore crushed to about 70 µm (200 mesh). Transmitted light study is particularly suited to gangue minerals, such as quartz, carbonates, and feldspars, and to the study of alteration processes and products. It has some applications to liberation studies. Minerals are identified in transmitted light by observable and measurable optical parameters, such as cleavage and twinning. Figure 1 is a photomicrograph of the mineral microcline, (original

Jan 8, 1985

By G. Van Weert, J. F. Breedveld

Both regular and Silver Impregnated Activated Carbon (SIAC) were studied for their effectiveness in removing WAD (Weak Acid Dissociated) cyanides from solutions at pH = 10. SIAC has already been shown to be effective in the removal of free cyanide down to 30 ppb or less. The present work deals with complexed cyanides. Zinc cyanide was used to represent the WAD component. At pH=10, in either batch or column tests it was not possible to lower the total cyanide in solution from either 30 or 8 ppm to less than 1 ppm, using SIAC, regular activated carbon as received, or after grinding. Silver (metal) impregnation of the carbon was not beneficial in the removal of WAD cyanide. However, when silver is added as silver ions (nitrate), the cyanide is adsorbed as silver cyanide in preference to zinc cyanide. The latter compound converts to zinc (hydr) oxide. This way, the cyanide concentration in solution can be lowered below 1 ppm, even when zinc cyanide is already adsorbed on the carbon used. A single exploratory test with added copper ions indicated a similar effect for that system.

Jan 1, 2004

By J. R. Sturgul

Computer simulation models of working mines can be a great benefit to mining engineers. Such models have been used in mine planning (how many trucks-shovels to have, when to add new equipment, etc.) and mine design (should a dispatch system be purchased, where is the optimum location, for mine equipment, etc.). A simulation model can be thought of as a dynamic representation of the mine. It can be easily changed to reflect a variety of situations. A major problem for the engineer is how to present the results of the simulation study. This has now been overcome by means of animation to present the results of the simulation. The main simulation languages in use for discrete system simulation are SLAM, SIMAN and GPSS/H. Each has animation with SLAMSYSTEM for SLAM, CINEMA for SIMAN and PROOF for GPSS/H. Animation with SLAM and CINEMA have been on the market for several years whereas PROOF is a relative newcomer and has features not found in other animation software. This discussion will be confined to PROOF. Some of the comments will apply to all simulation and animation software.

Jan 1, 1995

By I. S. Parrish

Reserve audits have increased in recent years as more companies, especially juniors, enter the ranks of producers. Corporate and individual investors are seeking corroboration of stated reserves. The reserve audit satisfies this need. An audit assures investors that the reserves, as presented, are a reasonable and accurate approximation of the quantity and grade of the economically viable material present. The reserve audit verifies that there are no fundamental errors in logic, style or the data base, and that the reserves, as given, may be used for mine planning or economic forecasting. Reserves that pass an audit may be used with confidence in preparing cash flow projections and in deriving net present value or internal rate of return on any given project. This article describes what a consultant does while performing the reserve audit. In performing an audit there are four general areas of concern that must be checked: definitions, parameters, data and procedures. In each of these, the auditor must convince himself that the reserve study has complied with governmental regulations and guidelines, professional standards and industrial practices. Any deviation from these norms must be identified and its effect upon the appropriateness of the reserves evaluated. By concluding that a reserve study passes his audit, the reviewer is stating that there are no fundamental errors in logic or style and that spot checks have revealed no substantive errors in procedure or mechanics. The responsibility for the reserves remains with the entity that compiled the original study.

Jan 1, 1990

By Donald E. Dickie

At Sifto Canada's Goderich salt mine near Goderich, Ontario, the stress control method of mining was introduced to overcome increasing roof failure problems. After successful testing, the conventional room-and-pillar mining method was converted entirely to the stress control method. This conversion has successfully stabilized the ground, increasing the extracton ratio from 38% to 50%. At the same time, it reduced the ground control and rehabilitation cost by more than 80%. The success of the conversion is due to the quantitative technique of mine analysis that was developed to ensure that the conversion was safe and reliable. A finite element model of the ground was constructed to predict and validate the safety of the stress controlled mine opening. A system of in situ stress-property measurement instruments was developed to obtain input data for the computer model as well as to evaluate its output quantitatively with regard to time and location. History of roof problems Severe roof safety problems have been encountered at Goderich Mine since it opened in 1959. These problems continued into the 1980s. Following excavation, the roof strata started to deteriorate by slabbing. Even after roof rehabilitation, deterioration continued to progressively higher roof elevations, requiring repeated rehabilitation. The operational impact of these roof failures was severe, ranging from a considerable safety hazard to major production interruptions.

Jan 1, 1993

By Charles Fisher

When considering the biodiversity of fauna endemic to hydrothermal vents or hydrocarbon seeps one must consider not only the numbers of unique species, but also the physiological diversity (and potential biochemical/physiological uniqueness) of the fauna. The deep ocean ridge system is home to some of most extreme animal habitats found on Earth. In addition to the high pressure, low temperature, and lack of light characterizing the deep-sea in general, hydrothermal-vent environments are characterized by toxic chemicals and temperatures that would be hostile to most other animal life. Perhaps even more challenging than the absolute levels of chemicals, dissolved gases, and temperature with which vent animals contend are the extreme gradients in time and space of all of these parameters. For example, temperatures around some vent animals can fluctuate from ice-water to hot-tub levels over seconds and can exceed 350°C only inches away. Specially adapted animals not only tolerate these conditions, they often thrive under them. As a result, the biomass of many deep ocean ridge ecosystems rivals that of coral reefs and tropical rain forests. In the Gulf of Mexico, hydrocarbon seepage through the sea floor driven by salt tectonics results in environments that are geologically very different from hydrothermal vents, but are geochemically similar enough that closely related animals are found in the two habitats. This includes seep mussels, clams, shrimp, worms, and other animals whose close relatives are found in hydrothermal vent environments. Although many aspects of the biology of the animals from the two environments are very similar, there are also significant differences in their life histories and physiologies that reflect the fundamental differences in the geology of their habitats.

Jan 1, 2008

By James M. Murphy

INTRODUCTION In the fall of 1983, the fourth new Rapid Transit System constructed in this country in the last forty years will go into revenue service. The Baltimore Metro will bring to this major Mid-Atlantic seaport the first phase of a planned intermodal transit system, serving a metropolitan area with a population in excess of four million people. Originally, the Mass Transit Administration (MTA) considered construction of a twenty-eight mile system known as Phase 1. Its two lines would run from the center of Baltimore City, one going northwest to Owings Mills and the other south to Anne Arundel County. Legislative approval was granted in April, 1976; however, funding was limited to constructing a segment fewer than eight miles in length, along the northwest corridor from Charles Center to the Baltimore City county line. This segment is known as Section A. The project is 80% federally funded and 20% state funded, with a capital cost estimate of $797,000,000 to complete. This report addresses the development and implementation of a Coordinated Insurance Program for the construction phase of Section A, and includes a description of the associated risk management process. GENERAL DESCRIPTION OF SECTION A Section A of the Baltimore Metro is composed of a rapid transit line eight miles in length which serves the northwest corridor between Charles Center in downtown Baltimore and Reisterstown Plaza at the Baltimore City county boundary. The line is completely grade separated and, once operational, will provide high speed automated rapid

Jan 1, 1983

By J. W. Danni

Today's mining industry faces many challenges. Perhaps none is more important than the challenge of improving our industry's public image. Opinion polls document public concern for a clean and safe environment. As part of that public, the mining industry must share that goal. The public is now the most powerful environmental group in society. And the public wants the environment to be protected. In May 1989, Edgar S. Woolard, chairman of DuPont, spoke to the American Chamber of Commerce. He said that industry's continued existence "requires that we excel in environmental performance and that we enjoy the non-objection - indeed even the support of the people and governments in the societies where we operate." In effect, Woolard called for "corporate environmentalism." He defined it as an "attitude and a performance commitment that places environmental stewardship fully in line with public desires and expectations." Environmentalism is no longer a fringe activity, but rather is now clearly in the mainstream. How can we meet public expectations and improve our image as an industry? One of the best ways is to plan, design and operate our mine facilities with environmental responsibility and social concern. The Mineral Hill Mine provides a good case study of a facility that has made this commitment. The project used an inter-disciplinary, multiagency task force, citizen advisory groups and engineering and design considerations. As a result, Mineral Hill achieved cost-effective permitting. At the same time, the operation demonstrated effective "corporate environmentalism."

Jan 1, 1992

By J. E. Stephens

US Borax began exploration in southeast Alaska in the summer of 1971 with a staff of two, Barry Watson and Jackie Stephens, based in Spokane, WA. After several years of prospect examinations in the islands west of Ketchikan, AK, and with the able assistance of prospector-pilot Kenny Eichner, Jackie Stephens proposed and organized a boat-based, helicopter-supported, stream sediment sampling program to explore the western contact of the Coast Range intrusive complex on the mainland. The rationale for this included: the extension of known mineral trends from Canada into southeastern Alaska along favorable geologic zones; the western contact area of the Coast Range intrusives with metasediments and metavolcanics was a favorable target for metals exploration as shown by numerous small prospects. Knowledge gained from mineral exploration of the island areas indicated that they were well mineralized, but already well explored, and that the known mineral potential was probably present in subeconomic quantities (Brooks, et al.). Publications of the US Bureau of Mines and other scientific agencies were gathered and every prospect within the southem southeastern Alaska area was plotted. This in itself lent a tremendous amount of knowledge to the total exploration program. US Borax's McLean Arm copper property on Prince of Wales Island was drilled and dropped while this compilation of data was proceeding. We found that many companies had followed one another around the island areas, but little or no exploration had been done on the west side of the Coast Range, and that many explorationists flatly stated that the west side of the Coast Range was barren of mineralization. In summary, although some of the shoreline and near shoreline areas of the mainland had been explored, no organized boat-helicopter exploration program had been done along the favorable western zone of the Coast Range Intrusive complex. We decided to use a boat as a floating hotel for the crews that were to be helicoptered into the back country from tidewater for our initial stream-sediment sampling program.

Jan 1, 1991

By Garrett R. Hyde, Aleksandar Stojsic

Introduction Economic pressures in the international marketplace have spurred advances in almost every facet of flotation. New developments have occurred in flotation chemicals, flotation machines, and in the application of automated process control technology to grinding and flotation. Many of these advances are the results of concerted efforts to apply the knowledge obtained from basic flotation research over the past 15 to 20 years, to develop industrial technology for the more efficient separation of sulfide minerals in real ores. Mining company executives and equipment manufacturers are being called on to make decisions for incorporating some of this technology into present operations. This discussion is limited to two developments now at the stage of being engineered into industrial scale operations. They are control of the electrochemical environment or redox potential of the slurry, and control of bubble size in column flotation. Potential economic impacts are noted. Froth flotation Froth flotation makes use of differences in the surface properties of finely ground minerals to obtain separation. If the mineral surface is water repellent, the mineral particle will stick at the air-water interface of a bubble and float. If a mineral surface is not naturally water repellent, a chemical collector is added to the slurry to make it so. The collector must adsorb on, and make water repellent only the mineral to be recovered, not the gangue minerals. To achieve this degree of selective adsorption, chemical modifiers may have to be added to the slurry. Modifiers include pH regulators, activators, and depressants. Electrochemical control One of the most significant developments in recent years in the area of mineral processing technology is the recognition that collector adsorption of sulfide minerals is an electrochemical process. Consequently, flotation of these minerals depends on the electrochemical or redox potential of the system. Many of the modifiers used to control various flotation processes are actually potential controlling reagents. For example, the role of well known depressants, such as cyanide, sodium hydrosulfide, and sulfur dioxide, is essentially to

Jan 7, 1987

By Pan Eimon

She was young, beautiful, intelligent, virgin. Her name was Barbara and she captured the attention of many men, especially those in dangerous occupations. Her rich and doting father was hopeful of making an advantageous marriage for his daughter. Instead, she defied him, became a Christian, and refused to marry. Traumatized, he killed her and was himself struck dead by lightning. That is not the plot of a new soap opera. It is the melodramatic story of a Turkish teenager who was martyred in the third century but lives still as patron saint of mining. The story begins with a 20th century fact. Santa Barbara is a figment of imagination - perhaps based on an early oriental folk heroine, embroidered by a seventh century storyteller, and reworked by a ninth century Greek martyrologist. The authoritative Lives of the Saints reports: "There is ... Considerable doubt about the existence of a virgin martyr called Barbara and it is quite certain that her legend is spurious. There is no mention of her in the earlier martyrologies, her legend is not older than the seventh century, and her cult did not spread until the ninth." The Catholic Dictionary adds that the Barbara story is probably "a pious legend." Widely revered Santa Barbara was one of the most widely venerated saints of the Middle Ages. She became the patron, not only to miners, but also to artillerymen, engineers, architects, builders, stonemasons, gravediggers, and sailors. Mines, mountains, churches, and places bear her name. Barbara's feast day, Dec. 4, appears on the most ancient holy day calendars. And a Barbara festival is still celebrated throughout central Europe, in Spain, and in mining areas of Latin America on that date. The Pacific coast channel, the city, and the mission of California are named for Santa Barbara. An expedition, sailing that coast under Viscaino in 1602, was saved from shipwreck on Dec. 4 after the sailors prayed for Barbara's intervention. Franciscans gave her name to the modern Franciscan Province of Santa Barbara, which embraces six western states and the Philippine Islands. Barbara is intimately entwined with mining. The origins of both saint and profession are lost in an-

Jan 11, 1985

By C. J. Johnson, C. J. Bise

Introduction Coal extraction by continuous miners (CM) is currently the most common underground method in the US industry and accounts for slightly more than two-thirds of the nation's deep mining production (National Coal Association, 1987). Even if longwall mining should become more commonplace, it can proceed only after ventilation and access entries have been driven by CMs. Since an area of concern continues to be the effects of the dust generated on the health of mineworkers, this paper discusses the relationship between the elemental compositon of mining-generated airborne dust sampled from the immediate ventilation return of a CM and laboratory-generated dust derived from channel samples taken from the mines. There are several potential contributions of this type of study to the coal mining industry. First, after more fundamental knowledge of the causes of Coal Worker's Pneumoconiosis (CWP) is learned, the laboratory-generated respirable dust could be used to identify a potentially hazardous coal seam. Also, this study could possibly aid in understanding the fundamental causes of CWP by producing mining-simulated samples of coal dust that could be used in epidemiological studies. Further, assuming that there is no difference in the elemental composition of a drill-core sample and a channel sample from the same location, a mining company could predict a new mine's respirable dust elemental composition in the immediate ventilation return by using exploratory drill core samples of the roof, coal, and floor rock to prepare the laboratory dust. Ventilation engineers could then use engineering design and control measures during premine planning to reduce the incidence and severity of CWP by better ventilating the potentially hazardous coal seam. If this proper planning prevented any future changes to the ventilation equipment and mine design, much time and money could be saved. Scope of work To investigate the variability of the chemical characteris tics of respirable dust, airborne dust samples from eight underground coal mines located in the eastern and midwestern United States were collected with eight-stage Sierra Model 298 Marple cascade impactors, as well as 25 channel samples of mined material. Each channel sample was removed from the middle of the coal face before mining occurred. Sampling of the mining-generated dust was conducted by Lee (1986) by sampling the entire working sections, primarily for characterization purposes, to obtain information on the locational variability of dust characteristics. Research performed for this study used the elemental analyses of the mining-generated dusts he sampled in the immediate ventilation returns of CMs. The procedure that was used to produce the laboratory-generated respirable dust was based on the Hardgrove grindability test since it reflects the pulverizing characteristics of coal. This test was chosen for several additional reasons. First, it is repeatable and reproducible. A consistent amount of input energy is used as well as a specified size range of feed material to be crushed (the channel samples). Second, it is thought to generate secondary dust in a way similar to that of the crushing and grinding of the coal and rock as they pass through the arc-shaped cutting path of the CM's cutter head. The potential effect on dust generation by this secondary grinding mechanism may be at least as much as that produced by primary fragmentation, which is dust produced by the cutting action of the bit against the coal or rock (Roepke, 1984). Finally, the Hardgrove grindability test is well known and is used in the coal industry to guide mineral processing engineers in estimating the capacity of mills used to grind coal. One hypothesis of dust researchers in the Generic Technology Center for Respirable Dust is that the elemental as well as the physical characteristics of coal mine dust will make a difference in the incidence and severity of CWP. Coal mine dust is generated not only from coal, but also from any rock partings contained within the seam or any roof or floor material mined with the coal. Thus, coal mine dust may not have the same elemental characteristics as the coal being mined. Given that hypothesis, mixtures proportional to each thickness mined of roof, coal, and floor rock derived from the channel samples of the face areas from which the respirable dusts were generated by the CMs were used to produce the feed material that was pulverized in the Hardgrove machine.

Jan 1, 1989

By D. D. Carda, S. Dunn, W. E. Dunn, T. Storbeck

Gold chlorination which will be presented in this paper is limited entirely to the use of gaseous chlorine in a fluidized bed reactor at elevated temperatures in the absence of aqueous water. The only water used in this process is that which is used in scrubbing the effluents. Low temperatures are defined as those below 500°C. All experimentation for this paper was carried out on a laboratory scale, with all calculations extrapolated frpm this. Some of the data is drawn from work with other projects which have been operated at pilot and larger scale.

Jan 1, 1998

By H. Lyn Bourne

The is the 13th year for this column and the 12th in which the royalty data have been tabulated. There still exist some holes in the list of royalties that readers hopefully will fill. The most common mineral commodity is construction aggregates - either sand and gravel or crushed stone. In spite of their pervasive use nationwide, there are states from which the author has no information about royalties for either of these commodities. The reader can help - share information about these missing states and next year there will be fewer states without information. Severn Brown again sends helpful information from the Prospectors and Developers Association of Canada (PDAC). The PDAC Digest contained an article that distinguished between ‘net smelter return royalty' and ‘net profits royalty’ (Haase). The article also lists clauses and details that Brown suggests should be included in a net profits royalty contract.

Jan 1, 1994

By N. P. Reddy, L. Adler

The valuable Maximum Utilization Factor (MUF) concept has been extended to other rotating excavators beyond Stripping Shovels and Draglines. In this concept the boom reach and bucket capacity are multiplied to get an MUF, then normalized by dividing by the equipment weight. Statistical analyses were applied to the remaining shovels (hydraulic and cable), draglines, and backhoes. Positive correlations were found. Stripping Shovels and Draglines were also re-examined. The results provide an estimate of equipment diggability and encourages versatility by the interchange of the boom and the bucket. The concept further clarifies the existing equipment classification by delineating General Excavating, Loading, and Stripping kinds. The results also forecast trends, and noted innovative advances and possible retrogression. Extension to other boom excavators, such as front-end loaders, is recommended. The MUF concept provides one of the few indices of gross external characteristics available to the engineer-user of equipment.

Jan 1, 1991

By David Humphreys

Assumptions about future commodity prices need to be made with close regard to the purposes for which they are being used. Prices generated for financial planning or trading purposes are unlikely to be suitable for the longer run purposes of project evaluation and reserve estimation. In this latter context, price assumptions need to be realistic, stable and rooted in a rigorous fundamental analysis of long run industry drivers. Amongst the factors to be considered in such analysis are price history, production costs and structural dynamics. It is also important that prices adopted are consistent with other information being used by a company in its decision-making.

Jan 1, 2003

By Paul Chamberlin

Although performing a heap leach test is inherently simple, a lot of information beyond extraction, leach time, and reagent consumption can be obtained from a well designed test program. The following is a list of information to look for and acquire when performing column tests and field heap leach tests.

Jan 1, 1998

By TONY CICINELLI

INTRO PAGE

Jun 13, 2021

By R. Bernard

This paper will discuss innovative strategies that combine the capabilities of an Enterprise Asset Management (EAM) solution, sometimes referred to as a Computerized Maintenance Management System (CMMS) and E-Commerce solutions. Strategies discussed include solutions that minimizes the costs of operations through maximized equipment productivity and availability. Thusly, achieving the ultimate goal of keeping the cost per production unit as low as possible.

Jan 1, 2001