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By M. D. Max, A. H. Johnson

INTRODUCTION Gas hydrates have considerable potential to be a major energy resource owing to their apparent abundance in Arctic regions and along continental margins throughout the world (Kvenvolden, 1988). Yet, the oil and gas industry has been slow to pursue this opportunity. The primary reasons for this are the large conventional reserve base for natural gas worldwide and the perception that gas hydrate will not be a viable resource for another twenty or thirty years. Gas hydrates are thus viewed as a potential resource for the distant future, but not a valid investment for the near term. This paper addresses both global gas markets and gas hydrate technology, and shows that the commercial development of gas hydrate could proceed rapidly enough to constitute a near-term energy resource. GLOBAL GAS MARKETS The proven worldwide reserves of conventional natural gas are truly enormous, totaling over 6,000 TCF according to BP (2004). Moreover, those reserves have nearly doubled during the past two decades and now represent 67 years of consumption at the current production rates of 80 TCF per year (Fig. 1). This reserve increase has occurred even as global production of natural gas has increased by 67% during the same two decades (Fig. 2). While declining conventional gas reserves are a concern in North America, especially in regions where established infrastructure exists to bring gas to consumers, large new discoveries continue to be made elsewhere in the world. Indeed, in many parts of the world (such as the Middle East and parts of West Africa), natural gas has been regarded as an essentially worthless byproduct of oil production or exists in stranded gas fields. Given this situation, pursuing unconventional gas resources that are inherently riskier exploration targets and more expensive to produce would appear to have little rationale from a business standpoint.

Jan 1, 2006

By T. L. Muldoon

The bagging of dry pulverized products using fluidized air packers creates severe respirable dust problems in many surface mining operations. During bag filling, excess air and product blows by the bag valve/nozzle interface. After bag ejection, dust blows out of the bag valve. During conveying and handling dust is released from the bag valve and dirty bag surface. Overexposure of the bagging machine operator and bag handlers is common. This report describes the development and testing of a new dust control system for bagging machines. The system features a new bag clamp design to reduce product blowby during filling. A controlled vacuum system removes excess air from the bag before ejection, eliminating the problems after bag ejection and during conveying and handling. The system has shown significant reductions in dust exposure for both bag machine operators and bag handlers. These reductions are achieved with no significant effect on total mill productivity.

Jan 1, 1985

By J. C. Poulos

The West Elk Mine is located near Somerset, Colorado approximately 70 miles southeast of Grand Junction, Colorado and 72 miles southwest of Glenwood Springs, Colorado on state highway 133 (Figure 1). The West Elk Mine was opened January 20, 1982 as the Mount Gunnison #1 Mine operated by the West Elk Coal Company, a division of ARCO Coal. In the early 1990?s ARCO changed the mine name to West Elk Mine and the operating company was renamed Mountain Coal Company. Arch Coal, Inc. purchased the West Elk Mine in 1998. West Elk Mine has produced coal from three different seams. Coal was first mined from the F Seam, the upper most seam in the stratigraphic sequence, from 1982 through 1991. Coal was produced from the B Seam, the lower most seam, starting with continuous miners in 1991 and transitioning to longwall mining in 1992and continued on through October 2008. The development of the E Seam, which is the middle seam in the stratigraphic column, started in 2004 with longwall production commencing in 2008. The ventilation conversion from exhausting to forcing for the E Seam portion of the West Elk Mine was implemented in late October 2009.

Feb 27, 2013

By Sandip K. Mukherjee

This report presents the results of the economic analysis of several applicable alternatives to increase airflow in four underground coal mines. Pressure-quantity surveys were conducted underground and measurements were also made at the main mine fan(s). The existing ventilation networks were modeled using the modified Penn State ventilation simulator. The applicable alternatives were simulated. Performance data obtained from these simulation runs were utilized to conduct the cost-effectiveness analysis. The costs for each of the alternatives included capital, operating and operating costs. These costs were expressed as annual ventilation costs per active section in terms of dollars per cfm taking into account the economic life associated with each of the alternatives. The benefits were expressed as increased airflow quantity in the critical sections. A section of this report also deals with comparison of simulator predicted air quantity values against air quantity values measured under-ground. This volume constitutes Volume II of the report and contains the outputs of the computer simulation runs.

Jan 1, 1983

By E. M. Watkin

"Although Canada has achieved one of the highest living standards in the world, people and organizations have, over the past decade, begun to question the cost and means of this achievement. Concern has been expressed about the degree of environmental disturbance arising from industrial activities which have greatly contributed to our increased living standards. These industries include hardrock mining, pit and quarry operations, hydro-electric schemes, various agricultural enterprises and urban land developments.In the construction and operation of the above industries many environmental problems arise because the natural vegetative land cover is destroyed or drastically disturbed. Disturbance may occur to such a degree that revegetation is di ffi cult, often it appears impossible. Portions of the environment around such industries remain aesthetically unacceptable and appear to offer little or no potential for future resource use in wildlife, recreation or agriculture.The general public cannot dissociate itself from the activities of the aforementioned industries. It has, over many years, accepted the benefits and conveniences arising from those activities. Despite this, the increasing level of public concern imposes upon industry a need to alleviate or repair past, present and future environmental disturbance. Therefore it is incumbent upon industry to modify present technology or develop new techniques which would allow the disturbed environment to be easily and rapidly repaired."

Jan 1, 1975

By LUDWIG VOGELSTEIN

WE are indebted to Mr. Barbour for his valuable contribution to the literature on copper statistics; it is to my knowledge the only intelligent attempt to throw light on a much misunderstood subject. If I should appear to criticize some of his findings and arguments, I do not want to leave the impression that I do not appreciate the article; I think Mr. Barbour has been painstaking, and even where one might not agree with his conclusions, he has opened our eyes and stimulated us in our search for the truth.' It might be well to define the term "secondary copper" and to make a few remarks about the origin and the reasons for the variation of the supply. Mr. Barbour has touched on these points, but not sufficiently to make them clear to those not in the business.

Jan 1, 1931

By F. G. Scott

This document is a proposed program plan for mining environmental research to be conducted by the U.S. Bureau of Mines in support of industrial oil shale mining and processing. This program plan is one of three research alternatives being considered by the Bureau, each based on a different level of anticipated funding. This report documents the low funding level program plan.

Jan 1, 1980

By B. J. Barfield

Standard erosion plots (4.6 m by 22.1 m on 9 percent slope) were constructed on the Alston Surface Mine of Peabody Coal Company in Western Kentucky to evaluate the effects of placement technique and density on the erodibility and eroded size distribution from mine spoil and reconstructed topsoil. PLots were constructed with a dozer and scraper pan from shale spoil material, topsoil (A horizon) and subsoil (B and C horizon mixture) using soils stockpiled at the Alston Surface Mine. Plots were evaluated under fallow conditions with a tilled plot surface and two compacted conditions. One compacted condition was generated by tracking the surface with a dozer and rolling with a loaded scraper pan. The second was generated by rolling the surface with a solid wheel compactor. Rainfall was supplied with the Kentucky Rainfall Simulator at a rate of 63.5 mm h-l with the plots in three different soil moisture conditions; dry, field capacity, and very wet. Runoff was evaluated for flow rates, sediment concentrations, and aggregate and primary particle size distributions. Sediment yields and the Universal Soil Loss Equation E130 indexes were calculated from the data for each plot. The erodibility was calculated from the tilled plot data using a weighted soil loss and E130 value from the dry, field capacity and wet runs, and a cover management factor calculated for every other condition. For the topsoil and subsoil plots, sediment yield was greatest for the dozer scraper pan plots and lowest for the tilled plots. For the shale plots, erosion rates from the wheeled compacter plots were the highest and tilled plots the lowest. Average erodibilities were 0.14, 0.38, and 0.41 tons ac h ft-1 tonf-1 in-1 hundred ac-1 for the shale, subsoil, and top-soil plots. Cover management factors for each plot were 1.29, 1.42, and 1.17 for shale, topsoil and subsoil plots compacted with the solid wheeled compacter and 1.29, 3.79, and 2.51 for shale, subsoil, and topsoil plots compacted with the dozer scraper pan conbination. The accuracy of the Wischmeier erodibility nomograph was evaluated on the data collected. Erodibilities were accurately predicted for the topsoil plot and poorly predicted for the sub-soil plot. The accuracy of the CREAMS procedures for predicting the composition (size distribution) of eroded particles was also evaluated. The composition was well predicted for the topsoil plots, moderately well predicted for the shale plots and poorly predicted for the subsoil plots.

Jan 1, 1983

By Wayne Rogers, Kell Monro, Arthur Pacunana

The Phu Kham Copper-Gold Operation (PKM) is a large-scale open pit mine located in northern Laos. It was developed and is operated by Phu Bia Mining Limited (PBM) a Lao-registered subsidiary company of Australian incorporated, PanAust Limited. Production commenced at Phu Kham in 2008. Since the second half of 2016, there has been a significant increase in ore hardness and this has negatively impacted the PKM concentrator and resulted in lower SAG mill throughput rates. Over the remaining life of mine, the changing ore body and increase in ore hardness is forecast to continue as the pit deepens and the availability of softer blending ores reduce. To manage this risk, PKM initiated a Hard Ores Management Program to determine the most effective way to improve the mill throughput of harder ores. This involved conducting a number of innovative and process control driven blasting trials to optimize run-of-mine (ROM) fragmentation and other blasting outcomes. From 2016 to 2017, the performance of high powder factor blasting, electronic detonators and fast timing, high velocity of detonation (VOD) explosives, double-priming, and deck blasting, were individually and systematically assessed. The success of each blasting trial was then based on a ‘value for money’ criteria. This criteria is a cost / benefit analysis that weighed-up the additional cost to implement the trial against the measured improvement in mill throughput. Electronic and high VOD 90:10 emulsion:ANFO blasts were determined to have the best value for money, achieving an increase in mill throughput of 54% compared to baseline. This paper discusses how the implementation of an innovative and process control driven blasting trial methodology was able to successfully manage the hard ore challenges at PKM. In addition, this success was achieved without any major cost implications, safety incidents or process plant set-backs.

Jan 1, 2018

By R. Dippenaar

Traditionally, iron ore has been reduced with coke in a blast furnace and the hot-metal product of the blast furnace containing carbon, manganese, silicon, sulphur and phosphorous, was subsequently refined in a steelmaking furnace. During iron making as well as during steelmaking, significant amounts of slag are produced. Two decades ago, more than 13 m tonne of blast furnace slag and 4 m tonne of steelmaking slag per annum were produced in the USA alone. It is, therefore, not surprising that many attempts have been made to re-use iron and steelmaking slags. However, these slags are not merely metallurgical waste products but, on the contrary, their compositions and physical properties are judiciously designed to optimize the operations in the respective metallurgical reactors. The variation in composition and properties of blast furnaces lags are largely determined by the gangue in the ore and ash in the coke and much progress has been made in the re-use of such slag. With respect to steelmaking slag, emphasis has in recent years been placed on hot-metal treatment before refining and ladle treatment after decarburization. The bulk removal of silicon, phosphorous and sulphur from the hot-metal product of the blast furnace by specially designed slags prior to refining in a basic oxygen furnace, has reduced tap-to-tap time, lowered cost and produced steel of much higher quality. The use of synthetic slags in ladle refining techniques subsequent to decarburization in the basic oxygen furnace has resulted in reduced hydrogen and nitrogen contents and reduced solute impurities. Moreover, inclusion shape and composition control, again by the use of specially designed slags has led to the achievement of much improved mechanical properties of the steel. In these revised process routes, slag of different compositions are produced in the variety of unit processes and hence the re-use of steelmaking slags has become much more complex. Clearly, a thorough understanding of the design and use of these different slags is a pre-requisite to the development of re-use strategies. Japanese steelmakers have spearheaded attempts to reduce slag volumes in the individual unit processes and to strive towards ‘slagless steelmaking’ by recycling slags internally. Steelmaking slag volumes have been reduced on commercial scale from about 140 kg/tonne steel to 60kg/tonne steel. Moreover, model predictions have shown that, in principle, all slag can be recycled and the phosphorous extracted to produce fertilizer. This development is of particular significance since the supply of low-phosphorous iron ores is diminishing at an ever increasing rate. Keywords: slag, environment, iron, steel,

Jan 1, 2004

By J. O. Marsden

Part I in this series of papers considered the chemistry of medium-temperature pressure leaching of copper sulfide concentrates and reviewed the metallurgical testing and initial process development for this technology. This initial work resulted in the development of a process flowsheet utilizing superfine grinding (to a P98 of 12 to 15 µm and P80 of 6 to 7 µm), pressure leaching at 160° to 170ºC, followed by conventional solution extraction (SX) and electrowinning (EW) for the recovery of copper. However, this process required a significant amount of concentrated acid to be fed to the pressure leach vessel to meet the reaction requirements, representing a cost of between $0.03 and 0.05/lb copper (2006 basis) produced by the process. It was immediately recognized that the development of a process that did not require such a large acid addition would be advantageous. This paper, which is Part II in the series, describes the development of a process that incorporates medium-temperature pressure leaching and direct electrowinning (DEW) in a novel and innovative process flowsheet. Phelps Dodge (a subsidiary of Freeport-McMoRan Copper & Gold Inc.) refers to this as the ?MT-DEW-SX? process. Part III in this series covers the large-scale demonstration of the MT-DEW-SX process at Bagdad, Arizona; and Part IV addresses the development and design of a full-scale commercial application at Morenci, Arizona.

Jan 1, 2007

By Louis Schaffer

The objectives of the research were to determine whether a model health and safety program could be defined in terms which would enable its application to mines of all types, and, if such a model program could be defined, to determine through evaluations in two mining companies whether it would achieve measurable improvements. Volume 1 describes the model, how it was applied in the field and how it was evaluated. This, Volume 2, describes the literature and field research that preceded the model definition.

Jan 1, 1983

By Shail J. Butani

In 1986 the Bureau of Mines conducted a probability sample survey, Mining Industry Population Survey, to measure such employee characteristics as occupation; principal equipment operated; work location at the mine; present job, present company, and total mining experience; job-related training during the last 2 years; age; sex; race; and education. The population estimates are necessary to properly analyze the Mine Safety and Health Administration (MSWA) injury (includes illness and fatality data) statistics; that is, to compare and contrast injury rates for various subpopulations in order to identify those groups that are exhibiting higher than average injury rates. This report uses the survey's results to characterize the U.S. metallic mining workforce from March through September 1986. Similar reports have been published for the stone, sand and gravel, and nonmetallic mining industries, as well as for the entire metal and nonmetal mining (includes metallic, stone, sand and gravel, and nonmetallic industries) sector and the coal mining sector.

Jan 1, 1988

By G. G. Campbell

The Bureau of Mines in cooperation with Quaker State Refining Corp. conducted two underground-combustion oil-recovery experiments in the Venango Second sandstone in the Reno pool, Foster-Rena-Oil City field, Sugar Creek Township) Venango County, Pa.) to determine the applicability of the process for reservoirs producing Pennsylvania-grade paraffin-base crude oil. Tests were terminated when analyses of produced gas showed that a self-sustaining combustion front did not exist. It was thought that insufficient fuel had been deposited in the formation. Laboratory retort tests made after the second field test was concluded showed that crude oil from the Reno area would deposit enough fuel to support combustion if air flux, temperature, and time were maintained within defined limits.

Jan 1, 1967

By Gordon Revey

The challenge of managing blasting risk, types of risk, public perception, and a system for managing risk were covered in the first part of this article in the May/June 2000 issue of the Journal of Explosives Engineering. This final part of this two-part series provides a method for identifying specific blasting risks and reviews the importance of community relations.

Jan 1, 2001

By Zhang Chuanfu

Keywords: modified coprecipitation method, Ni-Co alloy powders, solid-solution oxalate, growth mechanism Homogeneous solid-solution oxalates of Ni2+ and Co2+ ions were synthesized by modified coprecipitation method and the composition and morphology of the fibrous solid-solution oxalates precursor were characterized by XRD, IR, DTA/TG and SEM analysis. The effects of feeding methods, pH values, precipitation temperature, reactant concentration, addition surfactant, alcohol washing and drying process on the morphology and dispersion of the precursor were investigated in detail. The experimental results showed that the coprecipitated powders have characteristics that are different from those of the mechanical mixtures with the same stoichiometry. Based on the observations of precursors growth and SEM morphology of the precursor, the oriented attachment was proposed for the well-aligned growth of the fibrous Ni-Co alloy precursor particles.

Jan 1, 2005

By Michael Tenenbaum

The importance of semikilled steel as a high tonnage grade has long been recognized. The increasing severity of the applications for which semikilled steel is used makes it desirable to obtain further information regarding the features of open hearth practice and ingot structure that can affect steel performance in subsequent rolling and fabricating operations. Accordingly, an investigation is being carried out studying the structure of various types of semikilled steel ingots. This paper reviews some of the observations made and information gathered in this investigation. By definition, semikilled steel may be considered to include all nonrimming steels in which the natural shrinkage occurring during ingot solidification is offset to an appreciable degree by gas formation. Accordingly, this type of steel includes the entire range intermediate between rimmed and fully killed steel. The resultant ingot structures range from those of steels that have been capped to suppress a weak rimming action to those steels that have been killed in the furnace or ladle to the extent that no mold deoxidizer is required. A survey reported to the 1946 -AIME Open Hearth Conference' reviewed the practices being used at 28 major plants for the deoxidation of semikilled steel. It was found that most plants divide the deoxidizing additions between the ladle and the mold—many of the plants adding only minor amounts of deoxidizer to the bath or none at all. Silicon, aluminum and titanium were the only elements used for ladle and mold deoxidation. Mold deoxidizers were added as capping additions or as uniformly fed additions. Several practices were reported in which the steel was deoxidized in the ladle to the extent that little or no mold deoxidation was needed. No reference was made to grades capped by using special mold designs or special closures over the top of molds. .Accordingly, specific examples of this type of practice will not be considered in this paper. It appeared from this survey of deoxidation practice that semikilled steel can be divided into three types, namely, capped semikilled, in which aluminum is added near the end of pour or after shut-off, intermediate semikilled steels, in which aluminum is fed uniformly throughout the pour, and semikilled steels requiring no mold deoxidation. In an attempt to cover the ingot structures obtained by the range of practices reported in the preceding survey, three series of experimental heats were made using increasing amounts of aluminum, silicon and titanium for ladle deoxidizers. The ladle deoxidizers were added as stick aluminum, 50 pct ferrosilicon and 20 pct ferrotitanium (4 pct carbon), respectively. Two methods of studying ingot structures were used. Ingots were removed from production, burned longitudinally and machined to allow observation of the central pipe and coarse blowholes. During the machining operation much of the finely porous subsurface structure was obliterated. Accordingly, observations were also made

Jan 1, 1949

By Michael Tenenbaum

The importance of semikilled steel as a high tonnage grade has long been recognized. The increasing severity of the applications for which semikilled steel is used makes it desirable to obtain further information regarding the features of open hearth practice and ingot structure that can affect steel performance in subsequent rolling and fabricating operations. Accordingly, an investigation is being carried out studying the structure of various types of semikilled steel ingots. This paper reviews some of the observations made and information gathered in this investigation. By definition, semikilled steel may be considered to include all nonrimming steels in which the natural shrinkage occurring during ingot solidification is offset to an appreciable degree by gas formation. Accordingly, this type of steel includes the entire range intermediate between rimmed and fully killed steel. The resultant ingot structures range from those of steels that have been capped to suppress a weak rimming action to those steels that have been killed in the furnace or ladle to the extent that no mold deoxidizer is required. A survey reported to the 1946 -AIME Open Hearth Conference' reviewed the practices being used at 28 major plants for the deoxidation of semikilled steel. It was found that most plants divide the deoxidizing additions between the ladle and the mold—many of the plants adding only minor amounts of deoxidizer to the bath or none at all. Silicon, aluminum and titanium were the only elements used for ladle and mold deoxidation. Mold deoxidizers were added as capping additions or as uniformly fed additions. Several practices were reported in which the steel was deoxidized in the ladle to the extent that little or no mold deoxidation was needed. No reference was made to grades capped by using special mold designs or special closures over the top of molds. .Accordingly, specific examples of this type of practice will not be considered in this paper. It appeared from this survey of deoxidation practice that semikilled steel can be divided into three types, namely, capped semikilled, in which aluminum is added near the end of pour or after shut-off, intermediate semikilled steels, in which aluminum is fed uniformly throughout the pour, and semikilled steels requiring no mold deoxidation. In an attempt to cover the ingot structures obtained by the range of practices reported in the preceding survey, three series of experimental heats were made using increasing amounts of aluminum, silicon and titanium for ladle deoxidizers. The ladle deoxidizers were added as stick aluminum, 50 pct ferrosilicon and 20 pct ferrotitanium (4 pct carbon), respectively. Two methods of studying ingot structures were used. Ingots were removed from production, burned longitudinally and machined to allow observation of the central pipe and coarse blowholes. During the machining operation much of the finely porous subsurface structure was obliterated. Accordingly, observations were also made

Jan 1, 1949

By T Grenne, R. B. Larsen

Paper presented at the conference on Economic geology in Europe and beyond II, models for mineral deposits in sedimentary basins, held in Keyworth, UK, 13-14 April 1994. Paper originally entitled: Processes in a newly discovered sulphide-PGE mineralisation in Norway. The Stormyrplutten mineralisation is hosted by a minor tholeiitic metagabbro of low-Ti composition intruded at a high level in the volcanic lithology. It is thought to be the subvolcanic counterpart of submarine basalts generated during an extensional episode of ensimatic arc evolution. The sulphide-PGE mineralisation occurs as stratabound pyrite, pyrrhotite and chalcopyrite disseminations with average grades of 376 ppb Pd, 313 ppb Pt, 40 ppb Au, 0.5% Cu and 0.08% Ni in a deposit 15-25 m thick. Locally the PGE content peaks at 2 ppm over 1 m. Microprobe analysis isolated 14 different platinum-group minerals, dominated by sperrylite, temagamite and borovskite and occurring as 1-20 micron compounds embedded in the main sulphide minerals or along the sulphide/silicate grain boundaries. Mantle-normalised plots reveal strong depletion in Os, Ir and Ru and enrichment in Pt, Pd, Cu and Au. The general decrease in Pd and Pt and increase in S up through the stratigraphy is similar to PGE distribution in the Darwendale subchamber of the Great Dyke in Zimbabwe, and may reflect strong fractionation of Pd and Pt in favour of the first droplets of sulphide melt; two reversals of the trend at the 4 and 12 metre levels represent replenishment with fresh magma and repetition of the cycle. In contrast to the Darwendale system, Cu and Ni also show peak concentrations in the first-formed liquids and Pt appears to have fractionated more strongly into the sulphide melt than Pd

Aug 1, 1995

By Lisa A. McDonald

The environmental compliance process affects all aspects of hardrock-mining operations, from exploration through post-closure. The primary components of the environmental compliance process are requirements under the National Environmental Protection Act of 1969 (NEPA) and the permitting requirements associated with various other federal, state and local laws. This study considers the Greens Creek Mine and the development of two other projects (Alaska-Juneau & Kensington). These mines were used as the foundation for a case study of the impacts of the environmental compliance process on hardrock-mining activity in Southeast Alaska. The case study presents the institutional and legal requirements, followed by a discussion of the impact of this process on the production and timing of the three mines. The results of this preliminary study reveal some interesting findings, some expected and others unexpected, regarding the impact of the permitting process on the exploration, development and (proposed) operation of the three mining projects in the Juneau area. Determining the cost of compliance with these requirements is an important step in evaluating the appropriate course of action to protecting the environment while providing the necessary raw materials needed for society. This preliminary study highlights the initial starting point for such an analysis.

Jan 1, 1992