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By M. R. Shahan, W. R. Reed

A laboratory apparatus (shield dust simulator) was designed and constructed to simulate the dust generated during the advance of longwall hydraulic roof supports, or shields. The objective of the study was to develop a tool that could be used to test the hypothesis that foam applied to a mine roof prior to a shield advance could be used to reduce the respirable dust generated during shield advances. This paper will outline the design parameters for the development of the system, as well as describe baseline testing of coal and limestone dust. Results show the average instantaneous respirable dust concentrations that occurred during simulated shield advance. Confidence intervals were calculated from the instantaneous respirable dust data to determine the repeatability of the data produced by the device. INTRODUCTION During longwall mining, miners can be exposed to respirable dust that is generated during the advance of hydraulic roof supports or shields. National Institute for Occupational Safety and Health (NIOSH) researchers have conducted numerous surveys of longwall mining operations, benchmarking the operating practices and dust control measures in use. It has been determined that the shields are responsible for 27% of the respirable dust that is generated on the longwall face [1]. The dust generated by the shield advances ranks second, next to the longwall shearer which is accountable for 43% of the respirable dust generated on the longwall face. The respirable dust generated during the advance of the shields can be a significant contributor to the respirable dust exposure of the mining personnel operating at the longwall face, especially since some of this dust is generated in the walkway. Control systems designed to reduce the dust levels generated during the shield advance have the potential to greatly reduce the respirable dust exposures of the personnel downwind of these activities. One control technology to decrease the dust generated by the shield advances would be to apply a layer of foam to the forward shield-roof interface prior to the shield advance [2]. The blanketed layer of foam would interact with the material located on the top of the shield during the advance, preventing a portion of that dust from becoming entrained in the mine air. This layer of foam would be applied using a foaming nozzle located on the longwall shearer body that would spray foam on the roof surface as the shearer passed. Substantial laboratory work has been completed to determine the feasibility of this type of foam application. NIOSH engineers have classified the various characteristics of foaming agents, using foam expansion ratio and drainage as important properties, as well as developed the mechanical systems required to apply the foam safely to the mine roof [2, 3]. The construction of an apparatus that could simulate the mechanical interaction between the dust-laden shield top and mine roof was necessary to adequately test the hypothesis that foam could be an appropriate control. A team of engineers designed and constructed a shield dust simulator system allowing for in-house testing prior to a full-scale field investigation.

Jan 1, 2019

By Neil B. Prenn

Mine Development Associates, Inc. was formed in March of 1987 to provide mine engineering assistance to the mineral industry. To be competitive with other firms, Mine Development must be able to provide quick and accurate ore reserves and mine plans for clients. Commercially available mining software was necessary for Mine Development to assist the client. This paper describes how Mine Development chose mining software, the time involved in getting up to speed, and several case histories of how the software is used. The case histories discussed include: * 3,000,000 ton gold deposit in Nevada. * 5,000,000 ton gold deposit in South Dakota. * 1,000,000 ton gold deposit in Australia. * +100,000,000 ton gold deposit in Nevada. * 25,000,000 ton carbonate deposit in California.

Jan 1, 1989

By James M. Link

The first rule of mineral deposits always seems to be: the deposit is never close to the market. With gems and precious metals, this is not much of a problem. But with most of the mineral commodities used in today's world, transportation becomes a major part of the cost to the consumer. In Japan, for example, more than 60% of the cost of coal to the consumer may be attributed to transportation. The purpose of this article is to examine pipeline transportation, particularly mineral slurry pipelines, as a means of getting the mineral to market. Pipelines Today Regulated pipelines in the US totaled nearly 724 Mm (450,000 miles) in 1980 according to the Federal Energy Regulatory Commission (FERC). Worldwide, more than 210 Mm (125,000 miles) of new pipelines will start construction in 1982 at an estimated cost of more than $150 billion. According to the Bechtel Corp., the period between 1982 and 2000 will see major growth in pipelines of all kinds. In North America, major movements of crude oil from Alaska and synfuels from the Rocky Mountains will require the construction of nearly 16 Mm (10,000 miles) of new pipelines. Nearly 42 Mm (26,000 miles) of new gas transmission pipelines will be needed to tap both US and Canadian arctic gas fields and move the gas to major markets on both coasts. Other pipelines will be required to move additional quantities of natural gas from the Rocky Mountains to more populous regions. Bechtel says more than 24 Mm (15,000 miles) of slurry pipelines will be needed to transport coal from both eastern and western coal provinces to the Mississippi valley and coastal areas. In 1980, 125 companies delivered more than 1 km3 (6.5 billion bbl) of crude oil and 652 hm3 (4.1 billion bl) of products in the US. At the same time natural gas pipelines transported 498 km3 (17.6 trillion cu ft). The reported investment by these companies was nearly $20 billion at the end of 1980. Advantages of Pipeline Transportation The obvious success and vitality of the oil and gas pipeline industry is based, at least in part, on the fact that pipelines are a very efficient and low-cost method of transportation. This fact, coupled with the need for lower cost trans¬portation, has led to the marriage of oil and gas transmission technology and the bulk mineral solids transportation industry. The off-spring of this marriage is the mineral slurry pipeline. Slurry pipelines have a number of advantages over other transportation methods. One of these is the fact that they are buried-out-of-sight, out-of-mind. Second, they are relatively small users of labor because they lend themselves to automation and remote, or even computer control. Third, they offer an attractive economic alternative to other transportation systems. For example, for a 1000 km (621 miles) distance, rail costs of 1?/ km (1.7?/ton-mile) are about equivalent to slurry pipeline costs. But, as the distance increases, pipeline cost per t-km continues to drop while equivalent rail charges remain essentially insensitive to distance. Where existing rail, barge, or ocean ships are available, the cost of new construction associated with a slurry pipeline probably will render it noncompetitive. However, where new rail or other construction is needed, the cost of a slurry pipeline is very competitive. About three-fourths of the cost of a pipeline is in pipe, fittings, and construction. Nearly a fifth of the investment is in pump stations and the remainder is in right-of-way, surface facilities, utility acquisition, communication facilities, and other support areas. The fact that pipelines are capital intensive is, at the present time, a mixed blessing. For example, the delivered cost of coal in a hypothetical project doubles when the cost of money rises from 9% to 17.5% per year. The largest cost element for delivered coal in this example is in depreciation and finance charges. The next largest cost element is electricity to power the pumps, with labor making up the smallest increment of the delivered cost of coal. World Slurry Pipelines The idea of a slurry pipeline was probably first investigated in the latter 19th century, but the first ones were successfully built and operated in the US in the early 1900s. Today, they are fairly common worldwide. Table 1 shows a number of the world's slurry pipelines. An examination of these will further emphasize the fact that pipelines provide a cost competitive alternative where new construction of a transportation system is required. In each of the examples, the desired mineral commodity is located in a remote corner of the world, markets are at a great distance, value of the commodity is not great, and no other transport system is available.

Jan 10, 1982

By Ahmet Unal

Use of radio frequency identification (RFID) technology to solve informational needs in isolated and restricted underground mining environments will be reviewed, giving specifications of some past and currently available systems. The advantages and disadvantages of using various frequencies, system configurations, and specific components, including their construction standards and capability, will be discussed. The remaining challenges to more widespread use of RFID systems for personnel and vehicle tracking will be identified, and recommendations concerning operating environment capabilities will be detailed. Finally, the ultimate requirements for maintaining system integrity during and following a coal mine emergency will be discussed.

Jan 1, 1997

By J. L. Yordan

An induction time apparatus has been constructed in the present work which has a sensitivity limit of 100-150 micro-seconds. The basic unit is similar to the one used by Eigeles and Volova (1960) and Trahar (1983), but it operates with a micro-computer and has a greater sensitivity. Using this apparatus, the flotation chemistry of the quartz-amine system has been studied. It has been found that at a given dodecylamminium hydrochloride concentration, the induction time is at a minimum at approximately pH 10.5. At this pH, the collector hydrolizes to form neutral amine and the flotation recovery reaches a maximumy,suggesting that iono-molecular species are the surface-active species responsible for flotation. This finding confirms the earlier conclusions obtained using the surface tension (Somasundaran, 1976; Finch and Smith, 1973) and contact angle (Smith, 1963) techniques. The induction time measurements have also been conducted as a function of particle size, collector concentration, indifferent electrolyte concentration and temperature. The results are compared with flotation data, and the activation energies for the bubble-particle adhesion have been calculated.

Jan 1, 1986

By S. C. Carniglia

Bayer-process alumina hydrate becomes in turn the source of a host of special products in addition to the calcines that feed aluminum reduction cells. Though relatively smaller in tonnage, specialty aluminas serve important industrial markets in an exciting and growing variety. Production methods and applications are discussed for: (1) trihydrate as flame retardant in organic materials; (2) high-surface-area transition aluminas as desiccants and scavengers, catalysts and substrates; (3) calcines for industrial ceramics, refractories, and abrasives; and (4) tabular alumina for refractories, bed supports and other uses.

Jan 1, 1977

By N. B. Aughenbaugh

Compacted clays are used as permeability barriers in many mineral engineering projects such as heap leaching, containment ponds, tailings disposal and earth dams. Source materials used for clay liners include a wide variety of sand, silt and clay admixtures that exhibit dramatically different engineering properties when densified. The permeability and plastic properties of fine-grained soils are reviewed with respect to the state of compaction as the water content varies. Be-cause they are weak in tension, compacted clays are susceptible to cracking when subjected to differential flexural movements. Designs of compacted clay liners must include an evaluation of their flexibility which is the ability of a fine-grain soil to bend plastically without cracking. This paper will also discuss the importance of flexibility with respect to soil types, compaction effort, failure mechanism and testing evaluation to the performance of clay liners in preventing seepage of pollutants from a containment site.

Jan 1, 1990

By N. D. Cristescu

The aim of the present paper is to show how a mathematical modeling of a creeping rock and that of an yieldable lining can allow us to obtain an optimization of the lining design and generally of the whole procedure and sequence of excavation-lining application. We follow the procedure presented by Cristescu (1989) Chap. 13, and Cristescu et al.(1987); for some other approaches see the literature mentioned, for instance, by Ladanyi and Gill (1988). We have in mind to describe the creep of the rock, i.e. the tendency of the tunnel to close in time, and to take into account that the lining itself may be deforming, i.e. possesses some rheological behavior. We start from the well known fact that "intelligent" lining, which are yielding to the pressure of the rock, may be much more successful in supporting creeping rocks than excessively strong, badly designed supports which are unable to resist to pressure of the rock, though these are oversized supports (too strong, too stiff, installed too early, etc.). In order to optimize the lining to be used for a certain rock, it is absolutely necessary to study in the laboratory the main mechanical properties of that specific rock and to formulate for it a reasonably simple mathematical model. Standard triaxial test results are quite enough to determine the model for the rock, combined with some creep tests which have to reveal the long-term behavior of rock (the so-called rheological model). What concerns the lining, we consider several kinds of linings existing today, for which a mathematical model was also formulated. One shows which is the interaction between the creeping rock? and the yielding lining and how can it be formulated in mathematical terms. Once written in mathematical terms, an optimization of the lining design and that of the excavation layout and support application sequence is possible. We will try to make the exposure as simple as possible, avoiding details and having in mind to give only a sketch of the problem, while the mathematical details could be worked out quite easy.

Jan 1, 1994

By M. M. Foss

Geophysical methods are gaining acceptance in the evaluation of coal mine ground control condition. The use of in-seam seismic investigations has contributed significantly to the body of information concerning ground control feature identification and analysis. Seismic methods have been used successfully in locating voids, faults, fracture zones, roof and floor rock interfaces, and more recently in characterizing in-seam stress distribution. Seismic tomography is an effective tool in data interpretation for several of these applications, but as is the case with other engineering application of geophysical techniques, there are limits as to how much substantive information can be interpreted from a given data set. This paper discusses some of the applications of in-seam seismic geophysical tomography, and the limits to which the transformation from raw data to information should be taken.

Jan 1, 1995

By J. Kretschmann

According to the model of product life cycles, the global coal mining industry is in the stagnation phase. The coal demand of the main consumer, China, has peaked in 2013 and is slowly declining. The Norwegian sovereign wealth fund, the world´s largest, has excluded coal-related companies for ethical reasons. Important players like the UN or the EU have already begun to describe pathways towards de-carbonization. Increasing competition between coal mining companies and the mining regions can be expected worldwide if companies want to keep their positions on the global and national coal markets. Companies will focus on the best deposits. European countries like France, Spain or Germany are only forerunners of this development - their centuries of coal production have been finished. The concept of Sustainable Development (SD) is fundamentally based on a model of progress where ecological, economic and social dimensions should be developed equally and positively. But without the idea of competition, the concept of SD is incomplete. Questions arise, such as: How can SD be realized on stagnating or declining markets without guarantees for companies “to live forever”? How can SD be a corporate goal in a phase of decline? How can declining mining regions sustainably progress into a better future? The German hard coal mining industry´s lifecycle has ended in 2018 after 60 years of stagnation and decline. As of 2019, all hard coal consumed in Germany will be imported, especially from Colombia, Russia and South Africa. What has been done in Germany to handle the coal decline in a sustainable way and the lessons learned from this process is described in this paper. It may be useful for mining regions who will face a similar future sooner or later. INTRODUCTION Principally, mining natural resources is a finite business that reaches its limits once the deposits mined are depleted, the resources can no longer be mined in an economically profitable way, or substitutes are pushing the mined products out of the market. An example for the latter is the increasing replacement of coal with natural gas and renewables in power generation in the USA. (Kok 2017) According to the model of the product lifecycle, the global mining hard coal mining industry has reached the stagnation phase. (Kretschmann 2000) Although the coal mining business is more a multi-regional than a global business the trend is obvious. The peak of coal use is behind us, especially because the coal demand of China is slowly decreasing since 2013. (Shell 2018) China´s government has announced investing $360 billion in renewable energy by 2020 and scrap plans to build 85 coal-fired power plants. In March 2018, Chinese authorities reported that the country was already exceeding official targets for energy efficiency, carbon intensity, and the share of clean energy sources. China’s energy regulator, the National Energy Administration, rolled out new measures to reduce the country’s dependence on coal. (Kejun and Woetzel 2017) Coal consumption in the US is facing a 16 % decline in five years from 800 to 670 million short tons between 2015 and 2019 and - according to the EIA – will not rise again. (EIA 2018) The decline is attributed to complex market dynamics from low gas prices because of the “shale gas revolution” (Kok 2017, p. 3) to federal environmental regulation like the Clean Power Plan. The United Nations´ UNEP Finance Initiative is cooperating with the Portfolio Decarbonization Coalition of institutional investors to implement decarbonization strategies across their portfolio. Amongst these investors is the New York State Common Retirement Fund, the third largest public pension plan in the USA. (UNEP 2017) The European Union has already begun to de-scribe pathways to decarbonization. (European Union 2018) The Norwegian sovereign wealth fund, the world´s largest, excluded coal-related companies for ethical reasons. The oil giants Total S.A. and Royal Dutch Shell, tradi

Jan 1, 2019

By Duluth Engineers' Club, Engineers' Club of Northern Minnesota

"In recent years, much has been said and written on Lake Superior ores, giving the impression that the quality of the ore is deteriorating in grade and that the reserve of high grade ore is rapidly being depleted. Average analyses of ore produced in this district since 1902 show that the average quality has been practically uniform since 1910, and now closely approximates the average for the total reserves of merchantable ore.The accompanying tables and charts show the average analyses for the past ten years, weighted according to tonnage: The chart above shows graphically the average natural iron content for the old range, Mesabi, and grand total Lake Superior ore shipments since 1902.During the last ten years the decrease in iron content for shipments from all ranges except the Menominee was only' .05 of 1 per cent, while for the Menominee ores there was an increase of .052 of 1 per cent. These tabulations and the chart prove that the average quality of the total annual production of iron ore from the Lake Superior district is uniform. Mining men of the district know that all of the merchantable ores of every ore body are being mined out cleanly, and therefore the present average iron ore content of total annual shipments from the district may be expected to continue as long as the present merchantable ore reserves last. There is no logical reason to expect a decrease in the average iron content. Furnaces require ore of definite quality, and if this quality of ore cannot be produced from the natural ore bodies, it must be produced by mechanical means—that is, by concentration of low grade ores or iron formation."

Jan 1, 1920

By Samer Sadek, Phoebe Cheng, Changmo Kwon, Myat Ohn

BART Facilities Standards (BFS) Structural Criteria is a living document that governs planning, design, and construction of all BART projects. Since its development, the document undergoes incremental changes and updates to reflect policy changes, changes in local, State, or national design codes and guidelines, advancements in engineering and technology, or based on the performance of past built infrastructure. In 2020, the BFS-Structural Criteria underwent a comprehensive update and was released with BFS version 3.2. This paper summarizes the updates to the Tunnels and Underground Structures Section of the Structural Criteria, and provides insights to the basis and logic of the requirements.

Dec 1, 2022

By R. K. Singhal, D. B. Stewart

A variety of equipment is being used for roadheading and tunneling in the mining industry. In United States drum-type continuous miners are used most extensively. In Europe and Canada mine roadways are driven mainly by roadheaders. The application of tunnel boring machines to coal mining is somewhat recent. Such machines are however being used on major projects driving main mine entries.

Jan 1, 1985

By Bo-Hyun Kim, Mark K. Larson

"Bumps remain a critical safety concern in underground coal mining, despite significant advancements in engineering controls. These events occur when relatively high stresses in a coal pillar in conjunction with low confinement exceed the pillar’s critical capacity, causing the pillar to rupture without warning. Floor failure often occurs and can be an indicator of bump risk, as it is strongly associated with brittle failure known as spalling under a lower confinement. Significant floor heave at a western U.S. coal mine has been observed where the pillar width in a three-entry gate road system was 53 m, while no significant floor heave was observed where the pillar width in another gate road system was 22 m. This phenomenon was widely reported in the region and at another mine in another western coal field it has been reported that larger pillars are always associated with floor heave. In this study, a spalling model based on the S-Shaped brittle failure criterion and associated with the anisotropic characteristics of the materials was used in FLAC3D. The observed floor heave phenomenon associated with the larger pillars was demonstrated using this modeling approach.INTRODUCTIONFloor failure in a coal mines often inhibits longwall mining operation, as large displacement of floor strata, known as floor heave, interferes with travel, access, ventilation, and equipment operation. Aggson (USBM 1978) investigated floor heave in West Virginia where underclay is relatively strong and high horizontal stress is present. It was reported that the failure mode is mainly by buckling rather than by plastic flow.This study was developed as part of an effort by the National Institute for Occupational Safety and Health (NIOSH) to better understand rock mass behavior in longwall coal mines in highly stressed, bump-prone ground. More specifically, this study attempts to explain through numerical models small energy releases in the form of floor heave. The authors believe that brittle rock failure is associated with both floor heave and some bump mechanisms, if not directly involved in their cause."

Jan 1, 2019

By A. K. Smith

Overexposure to noise remains a widespread, serious health hazard in the U.S. mining industry. Most other categories of illnesses and injuries associated with mining have improved, with the exception of hearing loss. U.S. Mine Safety and Health Administration (MSHA) coal noise data from 2000-2004 show that the continuous mining machine (CMM) is first among all equipment, accounting for 35% of noise overexposures. Joy Mining Machinery, in collaboration with the National Institute for Occupational Safety and Health (NIOSH), is conducting research to reduce noise generated by continuous mining machines. This paper describes a "JOY Designed for Noise Reduction" (JOY DNR; patent pending) tail section as a noise control for reducing the noise overexposures of CMM operators. Underground testing shows a 45% to 65% noise exposure reduction for the operator when comparing the JOY DNR tail section results to those for a standard machine. Utilizing this newly developed noise control, along with previously proven controls, will provide CMM operators an opportunity to be within the MSHA permissible exposure limit (MSHA-PEL). Mining Engineering, 2011, Vol. 63, No. 7, pp. 83-85. Official publication of the Society for Mining, Metallurgy and Exploration, Inc.

Jan 1, 2011

By Paul C. Lingo

Two recent antitrust cases, coming from widely separated areas, different industries and involving wholly different facts were decided by the Supreme Court on June 7, 1965. The decisions in there two cases may well prove to be the most important and far-reaching decisions in the field of labor law that have been handed down in the last 24 years. These cases, although quite dissimilar factually, had one common element. In both, the gravamen of the antitrust violation was bottomed on the terms of labor agreements negotiated by a multiemployer group. These cases are usually referred to as Pennington1 and Jewel Teat. Since a number of references will be made to the antitrust laws, it may be well to state briefly the applicable portions. Section 1 of the Sherman Antitrust Act makes "every contract, combination in the form of trust or otherwise, or conspiracy, in restraint of trade or commerce among the several states, or with foreign nations, is declared to be illegal...". Section 2 imposes criminal sanctions against "Every person who shall monopolize, or attempt to monopolize, or combine or conspire with any other person or persons, to monopolize any part of the trade or commerce among the several states...". Under Section 4 of the Clayton Act a person who sustains damages as a result of a violation of the anti¬trust laws is entitled to recover treble damages plus costs.

Jan 1, 1966

By D. E. Walsh

Over a period of seven years (1989-1996) the Mineral Industry Research Laboratory (MIRL) University of Alaska Fairbanks, has investigated the effects of temperature, residence time, and particle size on the degree of low-rank coal (LRC) upgrading for a non-evaporative, hydrothermal drying process, also known as hot water drying (HWD). Three Alaskan LRCs were used in this study: Usibelli coal (Seam No.4) from the Nenana Coal Field, Little Tonzona coal from near McGrath, and Beluga coal from the Beluga-Yentna field on the west side of Cook Inlet. Replicated, factorial tests were conducted. Experimental results indicate that most of the low-rank coal upgrading via HWD occurs rapidly within the first 10-20 minutes of residence time. Thereafter, the upgrading process slows down and over 100 minutes of additional residence time are required to produce similar percentage increases in coal properties to those achieved in the first 10-20 minutes. The properties of the hot water dried products were very sensitive to process temperature. Calorific value, carbon and oxygen contents, equilibrium moisture levels and Hardgrove grindabilities all appear to change linearly with temperature within the 275" C to 325" C range.

Jan 1, 1997

By Robert M. Jimeson

The competitive market potential for solvent refined coal is estimated. Market advantages of solvent refined coal are enumerated. Markets are possible in combustion, railroad locomotion, and carbon electrodes. The combustion characteristics are consistent with expected air pollution restrictions on the emission of sulfur and particulate matter. A market potential of sufficient size exists to support the initiation of solvent refining in the United States. The market analysis should help fuel producers determine the advisability of their undertaking the solvent refining of coal.

Jan 1, 1969

By W. Joseph Schlitt

Aqueous SO2 (sulfurous acid) is an interesting chemical compound. It functions as a reagent in various hydrometallurgical systems, but also represents an undesirable constituent in pyro- and hydrometallurgical effluent solutions. When present in such streams, SO2 can be oxidized to the more stable sulfate form to avoid exsolution of SO2 as a source of fugitive emissions and to simplify standard water treatment plant operation. This study provides information on the stoichiometry, kinetics and mechanism of SO2 oxidation using oxygen and an iron salt catalyst with solutions containing 0.05 to 20.0 g/l S02. Other test variables include iron salt concentration, oxygen pressure, temperature, degree of agitation and pH.

Jan 1, 1982

By CEM SENSOGUT, OZER OREN, YASAR KASAP

The mining sector, which is important in terms of raw-material and energy supply, is seen as a sector with high number of fatal accidents compared to other sectors. In this century of heightened occupational health and safety awareness, it is important to review past accident statistics and analyze current deficiencies using the information in inventory. Although there are many studies assessing occupational accidents occurring in the mining sector, there are few studies using the nonparametric linear programming method. There are many input and output parameters related to occupational health and safety. Nonparametric linear programming method has been found to be useful because it provides simultaneous evaluation of these input-output parameters, does not require functional form in the analyses and provides guidance on the improvement needed by the related parameter. However, this method analyzes data using a single period of time and does not take into account any changes in efficiency over time. In the literature, there is no study in which the change of occupational accidents occurring in mining and even other sectors over time is examined and the Malmquist total factor productivity index (MPI) is used. Within the scope of the present study, the aim was to examine the change of occupational accidents occurring in Western Lignite Corp. in Turkey, where underground and surface production methods are applied, between 2005 and 2018. It is the first time MPI is used to examine the change of occupational accidents over time. The DEAP 2.1 computer program written by Coelli [1] was used in the solution of the models [2].