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By Philani Larrance Ngwenyama, Ronald CW Webber-Youngman

The survival chances of trapped miners in underground mines depend on how quickly they can be located and rescued post-accident. During entrapments, emergency rescue is highly desired but can be hindered by the lack of positioning information when a fit-for-purpose missing-person locator system is not available. Various types of missing-person locator systems are available to aid search-and-rescue operations. From the wide range of the available systems, selecting the most suitable one becomes the next challenge. The available systems have not been measured if they are fit-for-purpose or not, and to what situation. This study proposes user requirements that can be used as a guideline to facilitate the system selection process. These user requirements provide a framework for the design and development of a fit-for-purpose missing-person locator system. The user requirements can also be used for evaluating the performances of a particular system, predict its success, and also drive future research toward developing new technology to enhance the capabilities of the current systems.

Apr 1, 2024

By William Gleason

"On April 4, 2017, the largest earth-pressure-balance tunnel boring machine (TBM) ever built finally completed its 2.7-km (1.7-mile) journey beneath Seattle, WA, nearly four years after it began boring the SR-99 tunnel that will eventually replace Seattle’s Alaskan Way Viaduct.By now, readers of this publication are familiar with the ordeal that began on Dec. 6, 2016, when the machine overheated and shut down. Until that point, the TBM, named Bertha, had grabbed headlines for being the largest in the world with a 17-m (57.6-ft) diameter face. But after the incident that stopped the progress, the headlines suddenly stopped focusing on the engineering marvel of the tunnel project and began asking what went wrong. Just 300 m (1,000 ft) into the tunneling journey the machine was stuck, unable to move forward and impossible to retract.The project’s contractors, Seattle Tunnel Partners,(STP JV) – a design-build consortium comprised of Dragados - USA, Tutor Perini, say a 20-cm (8-in.) steel well-casing buried in the path of the machine caused the problems that halted the TBM. The Washington State Department of Transportation (WSDOT) disagrees, and the issue over who ultimately pays for the repairs is now with the courts.Eventually, engineers determined the best way to get Bertha back to work was to dig a 36-m (120-ft), deep concrete lined shaft pit in front of the machine and lift the 1.8-kt (2,000-st) cutterhead out for repairs. The repairs took two years but eventually the machine resumed mining in January 2016. In April 2017, the TBM finished building the tunnel, breaking through at the tunnel’s north end near Seattle’s Space Needle, with little to no ground surface movement measured on the entire alignment.While the cause of the TBM breakdown and who should pay for repairs was debated above ground, the work below ground continued. David Sowers, deputy program administrator, engineering and program management with WSDOT, told Mining Engineering during the 2017 Cutting Edge Conference in Seattle that in addition to the technical marvel that the tunnel became, the fact the parties involved were able to work through the unprecedented challenge is a great example of how to overcome challenges on massive projects."

Jan 12, 2017

By J. P. A. Hortley

In conventional electrolytic copper production, looped copper starter sheets, on which the copper is deposited, are supported by hard-drawn copper bars. These bars have cross-sectional areas of between 1 and 1.4 in2. The suspension bars serve two purposes: firstly to support the cathode, which can weigh up to 150 kg, and secondly to introduce the electric current. IYI examined these two requirements in detail to see whether a better design could be achieved. Considering firstly the current carrying requirement, it wee noted that under normal refinery conditions, each cathode carries between 400 and soak. If one applies the generally accepted rule that 1 in of copper can carry 1000A4 a suspension bar need theoretically contain only 1/2 in2 of copper. This contention is supported by the fact that the 500A current passed through the cathode also appears to pass quite satisfactorily through the two support loops, which have a cross-sectional area of approximately 0.35 in 2. Turning now to the strength requirements, the cross-section of hard-drawn copper bar required to support a 150 kg cathode is relatively small, and easily met by the present designs. It is not, however, the static load applied by the 150 kg cathode immersed in the electrolyte which causes the damage to the hard-drawn copper, or even the increased static load of a 100 kg man standing on one foot in the centre of the bar; the damage is actually caused by the dynamic loads applied to the bare when they are dropped, thrown into containers, lowered too rapidly into the cell, or otherwise mistreated. The important requirement is therefore that the bar does not permanently bend. Its proof stress of limit of proportionality, rather than the amount that it deflects under static loading, should be the strength criterion. With the hard-drawn copper normally used for the manufacture of suspension bars, it has been observed that the copper becomes annealed during use, particularly at the end of the bar where the current is introduced. Thus, after a relatively short time, the cathodes are in effect being supported by annealed copper bars.

Jan 1, 1978

By M. Karmis

The determination of the surface area which may be impacted by underground mining is an important consideration in subsidence engineering. A number of parameters have been utilized to identify this influence area, most notably the angles of draw and break. This paper discusses the implications of selecting an appropriate "damage angle" for defining a potential damage area due to mining, within which surface structures may be impacted Furthermore, the influence of both mining and geological factors, such as mining width and depth and overburden lithology, on this angle is examined, using the Surface Deformation Prediction System (S.D.P.S) software. Finally, recommendations are given for applying these concepts in subsidence control.

Jan 1, 1994

By AKIHIRO YOSHIMURA, HIDEKAZU KATO, KOTA TAKATORI, YASUNARI MATSUNO

Chalcopyrite (CuFeS2) is the most refractory copper mineral when treated in conventional sulfate media leaching systems. This study is the first to examine the use of a dimethyl sulfoxide (CH3SOCH3), or DMSO, solution containing copper chloride (CuCl2) in the leaching of chalcopyrite. The DMSO solution containing CuCl2 could selectively dissolve the valuable metals of copper (Cu) and gold (Au) from chalcopyrite while leaving minerals with little economic value, such as pyrite (FeS2), and the penalty element arsenic (As) in the residues. Leaching chalcopyrite using a DMSO solution that contains CuCl2 offers a number of advantages, including eco-friendliness and easy operation.

By T. K. Kim

Iron, cobalt, and nickel in waste ferric chloride solutions were separated from each other by solvent extraction. The iron was extracted from the cobalt and nickel by the use of methyl isobutyl ketone, and then the cobalt was separated from the nickel by the use of a high-molecular-weight quaternary amine dissolved in a solvent of high aromatic content.

Jan 1, 1980

By Jozef S. Stachulak, Bruce R. Conard

INTRODUCTION The concern of occupational exposure to diesel exhaust pollutants is an important workplace issue for the mining industry. During the last three decades of diesel operations at Inco, a significant amount of research and improvement has been made in the area of work environment, and effective diesel operation. This paper will review the experience gained by Inco's Ontario Division from the implementation and the use of modern engines, improved fuel quality, and the exhaust control technology, coupled with adherence to proper maintenance and ventilation design and practices. Past monitoring practices and the current occupational monitoring program at lnco are outlined. A major new research initiative involving multi-stake holders in diesel performance is described. MINING IN THE SUDBURY AREA The discovery of nickel-copper ore in the Sudbury area dates back to the year 1856. The existence of this orebody was noticed when a strong compass deflection was observed by a provincial surveyor. This discovery, even though documented in official re- ports, failed to arouse any public attention at that time. In 1884, a rock-cut was blasted through a small hill near the village of Sudbury to permit laying track for the Canadian Pacific Railway (Boldt 1967). The rock-cut uncovered a body of massive sulfides with a copper content of over nine percent. The mineralization is concentrated along the outer margin of the Sudbury Basin, an oval-shaped structure having a dimension of 55 x 95 kilometres. The ore extends down-dip to to at least 3000 metres below the surface. The mining methods at lnco can be divided into two categories: "filled-stope" and 'bulk" mining. This division, in the broad sense, may also reflect the environmental conditions of the mine. In the past, the selection of a mining method was based on the size, shape, grade and the strength of the ore and its surroundings. The recent development of improved technology and mining equipment permitted wider application of low cost bulk mining methods. UNDERGROUND DIESEL EQUIPMENT The first diesel-powered machine, a 145-horsepower scooptram, was put into operation in March 1966, in a cut-and-fill stoping complex at Frood Mine. The number of diesel machines underground in the Inco, Ontario Division, mines was increased to 360 units by 1971,550 in 1977 (Rutherford 1978), and over 830 diesel-powered units in 1995. The following list indicates current mobile diesel equipment. LHD 194 Loaders 81 Trucks 28 Jumbo Drills 78 Personnel Carrier 101 Service Equipment 155 Locomotives 50 Bolters 30 Scissor Lift 113 About 20 percent of the LHD and truck units are equipped with electronic fuel controlled engines. COMPOSITION OF DIESEL EXHAUST Diesel exhaust contains hundreds of pollutants (Watts 19921, including components of unburned fuel and lubricating oil and products of incomplete combustion of the fuel and oil. These pollutants are emitted either as gases or as particles. Gaseous pollutants include carbon monoxide, nitrogen oxides, and sulfur ox- ides, as well as a variety of organic compounds, such as hydro- carbons, aldehydes, and polynuclear aromatic hydrocarbons. The particle phase, also known as diesel particulate matter (DPM), is the filterable portion of diesel exhaust. Figure 1 depicts the trimodal particle size distribution that arises from different mechanisms of aerosol generation (Cantrell and Rubow 1992). Primary combustion aerosols, including diesel exhaust aerosol, are formed as very small particles (in the 0.001 to 0.08 micrometre range), but physical mechanisms such as condensation and coagulation quickly transfer the aerosol mass from the nuclei mode to the accumulation mode. These processes result in a mass median diameter of approximately 0.2 micrometres for diesel particulate matter, and 90% of the particles are less than 1.0 micrometre in size. These particles have a high surface area, permitting the adsorption of different substances produced during combustion. Mechanically generated aerosols, on the other hand, typically contain particles greater than 1 micrometre in diameter. The particle phases of diesel exhaust contain three components (Bagley, et al, 1996) shown by Figure 2, namely: a carbon- aceous fraction composed mainly of solid-carbon particles, a sulfate fraction containing small hydrated sulfate particles, and a soluble fraction that contains compounds that are soluble in organic solvents and are adsorbed or condensed onto carbon core particles. These compounds consist primarily of higher molecular weight hydrocarbons and PAH's and may contribute 15% to 45% of the weight of the total particulate matter (Schuetzle, 1983). The control of these pollutants is necessary to ensure a healthy work environment. Proper engine maintenance, engine design modifications, improved fuel quality, and use of exhaust control technology, coupled with good ventilation practices, all

Jan 1, 1997

By J. C. Agarwal

A significant portion of the, coal mined by U. S. Steel is beneficiated to upgrade the quality of the resultant coke to meet blast-furnace requirements. Primarily because of degradation from modern mechanized mining methods, a considerable quantity of the coal to be beneficiated is in the 1/4-inch by 100-mesh size range. In the cleaning plants, this coal is usually cleaned on concentrating tables and then mechanically dewatered in solid-bowl centrifuges to 9 to 14 percent water. At some plants, to further decrease the amount of water shipped with coal, and to improve the coking characteristics of the coal at its destination, mechanical dewatering is followed by thermal drying. At U. S. Steel's-Alpheus preparation plant at Gary, West Virginia, approximately 50 percent of the total coal produced is in this fine size range, and two fluidized-bed dryers are used for the thermal drying step. The two fluidized-bed dryers are 14 feet in diameter and were designed by the Dorr-Oliver Company. Although the original design called for a rate of drying equivalent to 37 tons, of moisture per hour, presently they are removing twice that amount. This paper describes, the major problems encountered' in operating these dryers at the present, high capacities and how they were overcome.

Jan 1, 1963

By A. J. S. Spearing, T. Kostecki, D. Benton

The use of paste backfill in room-and-pillar coal mines in the United States needs to be fully investigated. This paper discusses a series of physical tests that were conducted to examine the support benefits of theoretical paste backfill regimens in Illinois Basin room-and-pillar coal mines, which necessarily included consideration of weak floor conditions. The series of tests included those simulating strong floor conditions, weak floor conditions, under-confined scenarios, and testing of actual coal-based paste backfill samples. The testing indicated that a paste backfill regimen utilizing a minimum backfill strength of 22 psi at a minimum fill height of 50% of pillar height could significantly increase the longterm stability of coal pillars in the Illinois Basin. Considering typical coal wash plant recoveries, 50% fill would be feasible.

Jan 1, 2014

By Dapeng Zhang, Brij Moudgil, Shibo Zheng, Chunhui Feng, Wenyi Song, Wending Xiao, Patrick Zhang

The separation of dolomite from phosphate is the most challenging problem in phosphate mineral processing. More than 50 percent of the phosphate reserve in Florida contains too much dolomite to process using current industry practice. The current way of producing phosphoric acid requires less than one percent MgO in the phosphate concentrate as the feed material. The Florida Industrial and Phosphate Research (FIPR) Institute has collaborated with worldwide experts in the field to address this issue. As a result, the industry is now offered three feasible options. Option I entails three methods for reducing MgO content in the concentrate from the Crago process, including adding a dolomite depressant in the rougher flotation step, dolomite flotation of the cleaner concentrate, and scrubbing the cleaner concentrate in quartz sand, which could reduce MgO content in the final concentrate by 20 to 40 percent. Option II involves the crushing and grinding of high-dolomite phosphate pebbles followed by dolomite flotation at slightly acidic pH using a new collector that does not require phosphoric acid as a phosphate depressant, achieving a final concentrate analyzing less than 0.9 percent MgO at about 87 percent P2O5 recovery. Option III is a gravity separation technique using an innovative separation jig, and its full potential remains to be demonstrated.

By A. R. Conroy

Microscopic observation of physical and chemical changes which take place in various materials under conditions of elevated temperature and controlled atmosphere can often yield valuable insight into the fundamental physical-chemical reactions which control processes in which these materials play an active role. The technique of high-temperature microscopy thus becomes an important tool for basic and applied research in pyrometallurgical and allied fields. Investigators have long been aware of this and through the years have applied the technique to a wide variety of problems. However, up to this time, application has been on a rather limited scale due to the high initial cost of equipment and the relatively low rate of production of data resulting from the complexity of the apparatus and attendant problems in manipulation.

Jan 1, 1964

By J. D. Megeath

In the October 1988 issue of MINING ENGINEERING, J.G. Wargo's paper discusses the problem of measuring and analyzing permeability, porosity, and fracturing in its relation to in situ leaching of disseminated gold deposits. This paper made me suspect that a good deal of information and analysis may have been done on this in reverse in the petroleum industry. Some years ago, I was involved with the US Geological Survey in a project studying the Devonian shale of the eastern United States. The Devonian shale contains gas deposits that have the characteristic of slowly seeping gas over a very long time period. To understand the rate of seepage, considerable study and analysis was done on the interrelationship of poros¬ity, permeability, and fracturing. The purpose was to find out how and why the gas could escape in the varying rates found in wells throughout the formation. It strikes me that this is the mirror image of the problem faced in attempting to understand how a cyanide solution will travel into a deposit. To possibly invent our own personal wheel a little faster, I would suggest a look at the work done on the Devonian shale. Some of it is contained in "Estimates of Unconventional Natural-Gas Resources of the Devonian Shale," US Geologi¬cal Survey Open-file Report 82-474, 1982, and "Additional Data for the Estimates of Unconventional Natural-Gas Re¬sources of the Devonian Shale," Open-file Report 83-676, 1983. It is entirely possible that some of this previous work could shorten the time required to make in situ leaching of dissemi¬nated gold deposits a profitable technique.

Jan 1, 1989

By J. D. Megeath

In the October 1988 issue of MINING ENGINEERING, J.G. Wargo's paper discusses the problem of measuring and analyzing permeability, porosity, and fracturing in its relation to in situ leaching of disseminated gold deposits. This paper made me suspect that a good deal of information and analysis may have been done on this in reverse in the petroleum industry. Some years ago, I was involved with the US Geological Survey in a project studying the Devonian shale of the eastern United States. The Devonian shale contains gas deposits that have the characteristic of slowly seeping gas over a very long time period. To understand the rate of seepage, considerable study and analysis was done on the interrelationship of porosity, permeability, and fracturing. The purpose was to find out how and why the gas could escape in the varying rates found in wells throughout the formation. It strikes me that this is the mirror image of the problem faced in attempting to understand how a cyanide solution will travel into a deposit. To possibly invent our own personal wheel a little faster, I would suggest a look at the work done on the Devonian shale. Some of it is contained in "Estimates of Unconventional Natural-Gas Resources of the Devonian Shale," US Geological Survey Open-file Report 82-474, 1982, and "Additional Data for the Estimates of Unconventional Natural-Gas Resources of the Devonian Shale," Open-file Report 83-676, 1983. It is entirely possible that some of this previous work could shorten the time required to make in situ leaching of disseminated gold deposits a profitable technique.

Jan 1, 1990

By S. Mathur

Oxide particles are commonly used as fillers in plastics, paper, rubber etc. (particulate composites). The successful fabrication of such composites is dependent upon the adhesive strength of the filler particles to the matrix. The compatibility of the matrix and the filler particles is generally enhanced by adsorption of surface modifiers such as surfactants and polymers at the particle-matrix interface. In order to develop a scientific basis for selection of appropriate modifiers it is necessary to understand their adsorption mechanism(s). Specifically, adsorption of polymeric additives is attributed to a combination of chemical and electrostatic interactions, hydrogen bonding and van der Waals forces. Hydrogen bonding has been suggested to be the primary adsorption mechanism for non-ionic polymers. However, a literature survey of Poly(ethylene oxide)(PEO)-oxide system suggested PEO, a non-ionic polymer, to be substrate specific. A systematic study was undertaken to investigate the adsorption mechanism(s) of a PEO on oxide particles. It was determined that strong Bronsted acid sites on the surface interact with the ether oxygen, a Lewis base, of PEO to induce adsorption. In this work characterization of PEO binding sites on oxides is reported and the mechanism(s) of PEO adsorption discussed.

Jan 1, 1997

By Earl Parker

The mining/mineral processing industry constantly faces the challenges of handling tons of material in a variety of processes such as crushing, milling, drying, belt transfer and loadout. These processes result in the production of high volumes of dust. A variety of dust detection and collection equipment is needed to properly manage these emissions to remain compliant with stringent air quality and safety requirements. Dust monitoring and bag leak detection can provide ways to reduce air pollutants, make work environments safer and remain compliant with requirements from the U.S. Environmental Protection Agency (EPA), U.S. Mine Safety and Health Administration (MSHA) and U.S. Occupational Safety and Health Administration (OSHA). There are several approaches to monitoring particulate emissions from dust collection equipment. These can include visual inspections, differential pressure gauges or bag leak detection systems. Bag leak detection and monitoring systems can be optical, light based or electrostatic/triboelectric. Recent developments have advanced the efficiency and reliability of electrostatic/triboelectric style monitors. New technological improvements have been developed that are based upon the principal of unifying dc (impaction) and ac (induction) signals and incorporating other proprietary circuit innovations. This higher signal resolution technology results in a more robust and stable measurement for detecting the presence of particulate in a dust collector emission duct or a flow process pipe.

By G. M. Matheson

Mining in the Colorado Springs coal field took place from the 1880's to 1940's. The depth of mining in the coal field varied from about 10 meters to over 150 meters. Review of sequential historical aerial photographs from 1937 to 1960 indicated about 2400 chimney subsidence sinkholes had developed throughout the study area. Statistical analyses of the location and size of these sinkholes with respect to the time since mining, depth of mining, mined thickness and type of mining indicated definite trends in the time of occurrence, size, and location of these features. This data is valuable in the assessment of potential future subsidence in this and other areas of similar mining conditions.

Jan 1, 1985

By D. R. Willmer, E. J. Haas

As national and international health and safety management system (HSMS) standards are voluntarily accepted or regulated into practice, organizations are making an effort to modify and integrate strategic elements of a connected management system into their daily risk management practices. In high-risk industries such as mining, that effort takes on added importance. The mining industry has long recognized the importance of a more integrated approach to recognizing and responding to sitespecific risks, encouraging the adoption of a risk-based management framework. Recently, the U.S. National Mining Association led the development of an industry-specific HSMS built on the strategic frameworks of ANSI: Z10, OHSAS 18001, The American Chemistry Council’s Responsible Care, and ILO-OSH 2001. All of these standards provide strategic guidance and focus on how to incorporate a plan-do-check-act cycle into the identification, management and evaluation of worksite risks. This paper details an exploratory study into whether practices associated with executing a risk-based management framework are visible through the actions of an organization’s site-level management of health and safety risks. The results of this study show ways that site-level leaders manage day-to-day risk at their operations that can be characterized according to practices associated with a risk-based management framework. Having tangible operational examples of day-to-day risk management can serve as a starting point for evaluating field-level risk assessment efforts and their alignment to overall company efforts at effective risk mitigation through a HSMS or other processes.

Jan 1, 2016

By R. J. McGregor, Deepak Malhotra

Engineers frequently encounter situations where decisions that are counterintuitive to the logically trained engineering mind are made because of other influences, whether they be financial, social, cultural, or environmental. Such influences can overrule the "logical" decision-making process. The aim of this book is to explore some of the nontechnical issues, which most engineers don't learn about in school, that can have a major impact in the mining industry. This chapter gives a brief overview of this volume and introduces the topics that will be addressed.

Jan 1, 2001

By P. Conrad, S. Rosenthal

"Engineers remain in demand. Job opportunities in the United States still exceed the number of students graduating from college with degrees in Mining Engineering. Although enrollment is up for freshman studying Mining Engineering, many of those students will either change majors or not complete their degree, maintaining that deficit of available Mining Engineers. What can be done to ensure that enough Mining Engineers will graduate to fill the needs of the mining industry over the next ten to 20 years? The authors believe that this need can be met by recruiting students to Mining Engineering programs who are genuinely interested in working in the mining industry. With this in mind, Montana Tech conducted its first Mining Engineering camp in July 2014 to get junior and senior high school students interested in careers in the mining industry by showing them that Mining Engineering is both an exciting and rewarding career. This paper discusses What a Blast! The 2014 Montana Tech Mining Camp. INTRODUCTION The concept of summer camps for high school students is not new. For example, Missouri University of Science and Technology has offered their “Explosives Camp” for several years. A large percentage of attendees to these camps discover or confirm an interest in Mining Engineering and enroll in the school’s program. The Dean of the Montana Tech School of Mines and Engineering challenged department heads to develop and offer summer camps for prospective high school students to get a taste of engineering with the goal being to improve recruitment for each discipline. Mining Engineering embarked on the concept of a summer camp in 2013 with a concept to provide a week’s experience in Mining Engineering during the summer of 2014. What it takes to progress from concept to reality, with some of the learnings to be shared, follows."

Jan 1, 2015

By H. Wesley Peirce

Arizona, in 1966, has continued to be the site of an extensive and intensive search for metallic mineral deposits. Over fifty separate entities--companies and individuals--have been actively engaged in mineral exploration programs, both large and small, in the Basin-and-Range portion of the State. Certainly, copper has been primarily responsible for the major efforts, although associated gold, silver, and molybdenum mineralization also has been important in the economic evaluation of potential copper deposits. It is not difficult to explain why the Basin-Range portion of Arizona is receiving such attention. Part of the story, undoubtedly familiar to most, can be illustrated by reference to three graphical presentations. For example, Figure 1 shows Arizona's annual copper production for the period 1955-1965, inclusive, and it demonstrates that new records of production have been accomplished in each of the past 6 years and in 9 of the last 11 years.

Jan 1, 1967