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By Clarence Hardy Long

In January of 1969 the United States Department of Health, Education and Welfare, through the National Air Pollution Control Administration, published a series of Air Quality Criteria (4'S) and Control Techniques (6,7) for air pollutants in compliance with the 1967 Clean Air Act which will affect the operation of all fuel burning equipment in the very near future. The design of equipment for the future which will use fossil fuels will also be affected. The purpose of this paper is to discuss some of the modifications which might be anticipated in the future for fuel burning equipment. One class of the several air pollutants looked at first by the USDHEW was the sulfur oxides. Other pollutants, such as nitrogen oxides, will be studied and controls for these will supposedly be written in due time. The obvious use of low-sulfur fuels, coal, oil and natural gas is suggested by the Control Technique(6). Conversion to other sources of power, such as nuclear energy and hydropower, is also suggested. The statement is made that since possible hydroelectric sources are limited and nuclear plants are not yet available on a large scale, the changeover to these sources of power will not be overnight. The bulletin (6) suggests that one possible solution in some areas may be the use of low sulfur coals for short periods of time during periods of severe air pollution. A curve showing the effect of this was given in the 1969 April issue of the Power magazine, where A. E. Boyer and F. B. Kaylor of Stone and Webster also described a computer program called DOSAGE which might be used to check weather, temperature, humidity, wind direction and velocity, and sound an alarm when that 0.1% of the time per season is here that requires the use of low-sulfur fuel. Inversion is eminent! Once this has passed operation on regular fuel may be resumed. This would mean a separate storage

Jan 1, 1970

By R. Fernando

"The National Institute for Occupational Safety and Health (NIOSH) National Personal Protective Technology Laboratory (NPPTL) is leading an effort to develop the next generation of self-escape breathing apparatus for egress from confined spaces in emergency scenarios. A backpack style closed-circuit mine escape respirator design was one configuration explored as part of the research imperative directed by the 2006 MINER Act. Stakeholder feedback from MSHA and at the NIOSH Breathing Air Supply Partnership Meeting indicated a smaller belt worn unit that does not sacrifice performance is desirable. This paper outlines some further technology advancements that may be investigated toward developing such a small-sized respirator. Technologies being considered are novel chemicals for improved carbon dioxide (CO2) absorption and oxygen (O2) production, eliminating a dedicated CO2 scrubber by incorporating its function in the spaces of the respirator’s breathing loop and storing O2 in a liquid form with long standby capabilities. When these technologies are applied to a future design, there is the possibility of having an escape respirator that can be belt worn and capable of being certified to 42 Code of Federal Regulations (CFR) Part 84 standards, including sub-part O for escape purposes including mine escape. BACKGROUND NIOSH NPPTL has a Research and Development effort to provide mine workers with state-of-the-art breathing air technologies to comprehensively support initial and continued self-escape, refuge alternatives, and rescue needs, resulting from mine emergencies. As part of this R&D effort, NIOSH invested in the development of a next-generation closed-circuit mine escape respirator (CCMER) which would be compliant with NIOSH’s respirator standard requirements, 42 Code of Federal Regulations Part 84, including sub-part O. The design features of the CCMER also address the MINER Act’s requirements for transitioning between devices without the need for doffing the initially donned device. It would also allow for improved protection when using voice communications with a donned device ."

Jan 1, 2018

By AMIR EHSAN KIANFAR, Moritz Ziegler, TOBIAS HARTMANN, ELISABETH CLAUSEN

Accurate positioning information is a central step in the process of increasing automation and digitalization in the mining industry. Underground mine environments are prime examples for GNSS-denied environments that pose several additional challenges for the employed indoor positioning system (IPS). This work presents an ultra-wideband (UWB)- based system specifically tailored for underground mine environments. Initially, the UWB technology is reviewed and basic concepts of IPS are explained. Both software and hardware are described in detail, including positioning algorithms, electrical circuitry and the mining-compatible enclosure. Finally, the results from field tests in an underground mine are presented and positioning performance and the influence of dilution of precision (DOP) on positioning results are empirically evaluated. The results show that the localization errors are mostly below 1 m. Individual zones of high localization errors are suspected to be caused by noise interference. Significant DOP influence due to the mining drift geometry can be confirmed. The system shows promising localization results for different mining applications, while influences negatively impacting the accuracy are presented as items for future research.

Jan 1, 2024

By Ronald J. Doll, John Elkin, M. P. Evans

The application of "Alignment Free” right angle shaft mounted drive systems offers improved reliability and reduced costs for surface and underground belt convey- ors. Comparisons to conventional approaches will cover installation, operating, maintenance, and spares inventory cost savings. Various options for belt acceleration and load control on fixed and variable length (booster) belt conveyors will be reviewed for operating performance, reliability, and total cost. Lastly, a case study of a successfully operating installation will be highlighted.

Jan 1, 1996

If a fire occurs outby an underground coal mine section, the immediate safe evacuation of miners from the working section should always take precedence. Unfortunately, in many cases, the dedicated escapeways (escape routes) for the evacuation of the miners become contaminated by the byproducts of fire from the adjacent entries. The purpose of this paper is to present the ventilation-control process that would keep the escapeway free from contaminants and, thus, available for travel. A few scenarios of mine fires in longwall development panels are analyzed and discussed. To perform these studies, a mine fire simulator (MFS) was used. This (MFS) provides a dynamic representation of the fire's progress (in real time) and gives a color-graphic visualization of the spread of oxygen, combustion products and temperature of the gases throughout the ventilation system. Also presented and discussed are ways in which the MFS can be used as a training and teaching tool for miners and, particularly, for ventilation and safety specialists.

Jan 1, 1997

By G. Blackwell

In the 1980's the Canadian surface mining industry was confronted by declining competitiveness in the face of low cost foreign producers and alternative materials. Low metal prices undermined profits for many mining companies. Restructuring, rationalization, capacity reduction, technology transfer, as well as favourable currency rates and higher commodity prices, helped revitalize the industry by the close of the decade. Now in the 1990's, however, the need to improve competitiveness for profitability has re-emerged in greater intensity. In the current climate it is considered that there are three strategies available to industry to ensure profitability: continued rationalization and restructuring; optimization of operating practice; and technology development and transfer.

Jan 1, 1993

By Joseph M. Keane

A number of innovative techniques exist for solving heap leaching problems in special situations. Some of these techniques have been successfully applied and others await an opportunity for application. Discussions in this paper will deal with gold heap leaching under severe thermal conditions, in tropical rainfall circumstances, in the absence of fresh water, and in other situations removed from the ordinary. CLIMATIC CONSIDERATIONS The success or failure of precious metal dissolution operations may be strongly dependent upon proper attention to the influence of climate. A few examples are given in the following paragraphs.

Jan 1, 1987

By MYRIAM FRANCOEUR, JOHN R.R. BOWLING, ADAM MCFADDEN

As duct-fan systems push the envelope of power, length and cost, their design calls for a more comprehensive technoeconomic analysis to ensure they deliver the expected results without failure and cost overrun. This work explores the numerous factors to include in the design of an extensive (semi-)rigid duct-fan system. Besides delivering a given airflow, the system must satisfy component limitations and power constraints during its lifetime. We evaluate the assumptions underlying the positioning of in-line booster fans in a long gapless duct-fan system and propose a strategy for specifying the location and blade pitch of successive booster fans to prevent system failure due to a partial vacuum.

Oct 1, 2022

By C. R. Peterson

A cutter vibration monitoring system is described which would map seam strata non-uniformities to permit guidance within the seam. An extremely simple and rugged transducer is used which is compatible with conventional cutters and cutter replacement practices, and believed to be suited to the mining environment. Laboratory tests show that the system can detect bedding planes in otherwise homogeneous material. A data display system which would employ the human operator's natural pattern recognition skill and judgement will be developed, Intended for remote control applications in general, the system is of direct interest for today's continuous excavators in coal or in any other machine excavated bedded deposit.

Jan 1, 1985

By Colin C. Brooks

The Ok Tedi gold/copper deposit of almost 800 million tonnes was found in I968 because at that time technology had just developed sufficiently to enable exploration of such an area, world markets and prices for copper encouraged exploration for large deposits of low grade ore, Papua New Guinea law encouraged exploration by groups with men, money, management and expertise necessary for successful prosecution of such a search and such groups were already operating in the country.

Jan 1, 1990

By L. Michael Kaas

In recent years a number of data processing and analytical techniques have proven to be useful to engineers and geologists in various segments of the mineral industries. Petroleum companies were among the first to utilize the computer to store well data files and to analyze that data for exploration purposes. A few years later, metal mining companies began to apply the same basic computer methods to problems in mineral exploration, ore reserve evaluation, and open pit mine planning. Because of the increasing complexity of planning for coal mines and land reclamation, a case study was undertaken to evaluate the usefulness of computer techniques to assist mining engineers and geologists in mapping coal deposits, evaluating coal reserves, strip mine planning and land management. The data used in the study was provided by the Illinois State Geologic Survey. This paper describes some of the results of that study. First, considerations for the development of a computer data base for coal deposits are presented. Next, a series of analytical techniques for processing the data is described. Finally, the case study is presented to illustrate how the coal data base and the analytical techniques could be used in actual practice.

Jan 1, 1973

By S. S. Hsieh

As part of a program to address long-term needs for ensuring adequate supplies of domestic phosphate raw materials, the Tennessee Valley Authority (TVA) has conducted considerable research on dolomitic phosphate rock beneficiation. The discovery that alkyl diphosphonic acids act as phosphate mineral depressants led to the development of several processes involving a carbonate flotation step for the effective beneficiation of these problem ores. Most recently, a partial de-oiling process in which the reagent consumption is greatly reduced has been developed. The reduction is achieved because part of the initial feed is beneficiated without passing through the separate carbonate flotation step. Using this method, a phosphate product containing 30.6-30.9% P2O5 and 0.7-0.8% MgO was obtained from a Florida dolomitic phosphate pebble which contained about 23% P2O5 and 2.0% MgO. The P2O5 recovery was 80.8-86.5%.

Jan 1, 1989

By R. W. Hagemeyer

By way of background. it is important to keep in mind that the information presented in this paper relates specifically to synthetically produced precipitated calcium carbonate (PCC) fillers. Natural calcium carbonate fillers manufactured by grinding limestone, marble and chalk, though having similar chemical and physical analyses to PCCs, normally contribute somewhat different performance properties in paint, paper and polymer systems. Many factors have been cited and numerous theories have been proposed for the observed differences. Particle size parameters, surface chemistry and particle morphology are the items most frequently mentioned. A discussion of this subject is beyond the scope of this paper.

Jan 1, 1989

By David C. Slack

In recent years public concern over the environment has grown enormously. A very aware populace has exerted pressure on its legislators to enact enforcement laws dealing with pollution. Among the different types of pollution, sulfur dioxide in the air is a large and readily identifiable constituent. Air pollution, according to the EPA, costs the U, S. billions annually with SO2 a major portion of this cost. Fossil fuel and oil fired power plants release better than 50% of the SO2 in the country. Thus great attention is being focused on the methods power plants are utilizing to control emissions. With a time schedule of compliance by early 1975, decisions are being made and systems chosen that will have to perform - and perform - and perform. Therefore, a large majority of the power plants are presently considering lime in the planning and operational phases of their stack gas desulfurization programs. The reasons for this are: Lime scrubbing has more development and pilot work completed than most other methods; the removal potentials are relatively high; the stoichiometric ratios are not excessive and, the process has relatively low capital and operating costs. Many pilot plant studies have been completed recently using lime and the first operational full scale lime scrubbing unit is now in the start-up phase at this time at Duquesne Light Company's Phillips Station here in Pittsburgh. Also, because of completed development work, the problem of solid waste disposal will also be tackled at this power station at the same time. There are various methods for the use of lime in scrubbing for S02, but for our purposes I would like to describe the cyclic wet lime process. This method called "Scrubber Addition of Lime" involves contacting the flue gas with a slurry of milk of lime.

Jan 1, 1973

By George R. Powe

If Campbell County, Wyoming were an independent nation, it would rank fifth in the world among countries with known coal reserves. Only the United States, Russia, mainland China and West Germany would have greater volumes available. Not too many years ago that statement would not have seemed important, because oil and natural gas had become our nation's principal fuels. Western coal deposits, particularly those of the Powder River Basin in Montana and Wyoming, and which underlie virtually all of Campbell County, were largely unknown. But recently, in response to the three-pronged stimulus of vanishing gas reserves, rising petroleum prices, and clean environment statutes, these vast deposits have been delineated and have become, in the minds of many, indispensable to our goal of energy independence. Not only does western coal lie in thick seams near the surface where it can be mined in huge quantities at low cost, but also it possesses another coveted attribute in this age of environmentalism: low sulfur content. At Burlington Northern we count ourselves at the forefront of those who believe this coal is essential to any hope for the government's "Project Independence." But to that belief we add another article of faith. We are convinced the economics of unit train delivery of this incredibly immense resource make it the only transportation system that can help us achieve energy self-sufficiency in this country.

Jan 1, 1975

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. M. Keane

Critical to successful dump and heap leaching for copper is an adequate testing program for evaluation of the applicable parameters. This paper deals with testing methods to establish best conditions for dump and heap leaching of copper so that commercial operations can proceed on a rational basis. Discussion is also offered of ore occurrences suitable for dump and heap leaching.

Jan 1, 1985

By V. Ramirez, M. Mankosa, G. Luttrell, E. Wasmund

"The performance of column flotation is strongly influenced by the effectiveness of the gas sparging system. Unfortunately, field studies suggest that gas injector systems used for column sparging are not always optimized. This unfavorable condition can create a number of issues within the concentrator including lower recoveries, poorer metallurgical upgrading, decreased capacities, increased circulating loads, higher reagent consumption and inefficient energy usage. To help overcome these problems, techniques have been developed that can be adopted by plant operators to improve sparger performance. These techniques include (i) design modifications to sparger components such as nozzles, distributors and internal parts and (ii) operational improvements such as proper balancing of gas/water flows, elimination of unnecessary pressure drops, and staged injection of frothing agents. This article reviews the important criteria that govern sparger operation and provides data showing how simple low-cost improvements can positively impact column performance. INTRODUCTION Column flotation cells have become the most popular machine design for industrial applications that require high purity concentrates. The superior metallurgical performance of column cells can be largely attributed to their unique geometry, which readily accommodates the use of froth washing systems. The wash water minimizes the nonselective entrainment of ultrafine gangue minerals that would otherwise be hydraulically carried in the water reporting to the froth concentrate. The larger height-to-diameter ratio of columns allows a deep froth to be maintained, which is essential to achieve even water distribution. Due to these unique features, column cells can provide impressive levels of metallurgical performance closely approaching the ultimate separation curve predicted using the flotation release analysis method (Kohmuench et al., 2007). Another very important feature of column cells is the design of the gas sparging system. One popular choice in the minerals processing industry is the Eriez SlamJet® sparger. As shown in Figure 1, this type of sparger operates by passing compressed gas through a small discharge nozzle. Fluid turbulence created by the exiting gas disperses and distributes small bubbles into the flotation pulp. The sparger is equipped with an internal moveable rod that is attached to a pressure diaphragm in the back housing of the sparger. The internal rod automatically moves back/forward and opens/closes the nozzle outlet when the compressed gas is switched on/off. This patented design effectively eliminates the accidental backflow of flotation pulp into the injection tube during shutdowns. The sparger can be operated as a gas-only injector or with the introduction of a small amount of high-pressure sparger water (Kohmuench et al., 2010)."

Jan 1, 2016

By Gerald Pinter, David Nitsche, Márton Bredács, Markus Haager, Andreas Frank

"The reliable prediction of service lifetime of tunnel constructions is of essential technical and economic interest. Polymers used for tunnel liners have to fulfill the requirement of 100 years lifetime. However, today no reliably proven test method is available which confirms such long lifetimes. The current paper introduces a recently started research project which focuses on lifetime prediction of highly flexible, very low density polyethylene (VLDPE) for tunnel geomembranes. Different PE grades in combination with different antioxidant packages are conditioned at elevated temperatures and immersed in different media. Initial results confirmed significant material aging of unstabilized resins already after exposure of up to 34 weeks, at least at the highest exposure temperature of 80 °C. To consider application relevant material properties the material characterization was done by means of tensile tests and dynamic oxidation induction temperature tests. High pressure liquid chromatography was used for further investigation of antioxidant consumption kinetics. 1. INTRODUCTION For a reliable service of modern tunnel constructions a sustainable proofing against water infiltration is essential for the lifetime of the structure. Geomembranes made of polymeric materials have been used successfully for tunnel lining since several decades. Whereas previous geomembranes usually were made of plasticized polyvinylchloride (PVC-P), due to several technical advantages today very low density polyethylene (VLDPE) has become a more and more popular material for such applications. For modern geomembranes, current guidelines expect minimum lifetimes of at least 100 years (ÖBV-Richtlinie 2012). In contrast to this requirement it must be considered that today no test methodology is available which reliably confirms such long lifetimes of polymeric materials."

Jan 1, 2016

By T. P. Harrington

Research efforts are just beginning to identify the acoustic signatures of very short pulses of sound associated with the fracture of single particles in an autogenous mill. This presentation will discuss the anticipated correlation between these data and the fundamental mechanisms of rock fracture It is hoped that further tests will help identify what design and operating parameters influence the acoustic spectra, determine whether different minerals have different spectra and correlate product particle size distribution with acoustic spectra.

Jan 1, 1980