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By S. G. Britton

Thin seam mining presents unique challenges when management or economic conditions require significant productivity increases. These challenges are increased depending upon the presence of various external factors such as labor unions, Federal and state regulations, and market characteristics. This paper explores the turn-around situation occurring at Tanoma Mining Company (TMC), a medium-sized underground coal mining company in central Pennsylvania, USA. Using a systematic approach of improving management controls and direction, labor relations, and communications, coupled with an intensive upgrade/rebuild/replacement program for equipment and systems used at the mine, TMC has begun reversing its' cashflow position from negative to positive within two years.

Jan 1, 1991

By Natalie White, Joel Asp, Allyz Kramer

"Minnesota has robust reclamation standards and have proven results in the taconite mining industry. Reclamation of overburden spoils, lean ore spoils and fine tailings from taconite production has generally been successful on the Iron Range, using a low input standard reclamation practice. Success at reestablishing vegetation on these landscapes is likely due to fairly favorable chemical and physical properties (e.g., few limitations due to acidic generating materials, metal toxicities and water and nutrient holding capacities). However, coarse tailings reclamation has proven more difficult, presumably due to lower nutrients and challenges with moisture holding capacities. Research efforts conducted since 1990 have struggled to develop a reclamation strategy for coarse tailings that meets the Minnesota Mineland Reclamation Rules, Chapter 6130. However, new breakthroughs in scram mining technologies are producing fine and coarse tailings that have not been encountered nor reclaimed in northern Minnesota. Scram mining in Minnesota is defined as those mining operations that produce natural iron ore concentrates. Innovative research is underway to investigate and determine successful reclamation strategies to reclaim scram mining tailings from these scram mining operations. The research program is conducted through collaboration with SEH, Prairie Restorations, Inc. (PRI) and Mining Resources, LLC with funding support from the Iron Range Resources and Rehabilitation Laurentian Vision Partnership minescapes grant program.The research program was divided into three phases:Phase I. Bench-scale testing to identify successful treatments to reclaim and restore scram tailings through evaluating surface soils amendments, viable seed mixes and plant germination, growth and densities. Phase I was completed in early 2015.Phase II. Field-scale pilot trial to test larger scale effectiveness of the treatments deemed successful in Phase I and test various vegetative assemblages and planting techniques focused on the unique challenges with scram tailing basins. Phase II was completed in late 2016 with a summary monitoring report.Phase III. Produce a technical report of results for the research undertaken in this study, as well as compile prior reclamation results used during previous Minnesota iron mining reclamation projects on tailings basin applications. Phase III was completed in 2017 with a summary monitoring report and recommendations."

Jan 2, 2018

By R. Kahrger

This paper is written to convey the latest developments in compact bucket wheel excavators (BWE's) operating in medium-hard rock and will serve to indicate that BWE and compact machines in particular do in fact have application in materials other than loose sandy soils and soft rock. A recently run extensive three month field test in hard marl, which was previously considered too hard and difficult to be handled by a BWE, is used as an example to explain some of the design requirements and problems associated with digging harder materials.

Jan 1, 1990

By Charles T. Holland

INTRODUCTION Insofar as I am aware, the term rock mechanics was not in the English dictionary in 1930 when I started my graduate program at West Virginia University. Hence, I never thought that I was undertaking studies in rock mechanics when I undertook to write a thesis on the physical properties of West Virginia coal. In this case, the subject was primarily concerned with the compressive strength of coal, the elasticity of the coal, the physical weathering properties of the coal and its friability. These days investigations of rocks pertaining to such properties are included in the term "rock mechanics". Other than this aspect, the principle interest in this part of my program was that I became interested in the strength of coal from the standpoint of structural purposes, and also became cognizant of its elastic properties as well as its energy storing properties. This research also tied in with a remark that Professor Lawall made in a Mining Methods class in 1928 when he remarked that a peculiar thing was happening in the southern part of West Virginia, namely, in the Pocahontas coal field. His remarks were to the effect that pillars were blowing up in the mines and when asked why he replied the cause was not known. The failure of three-inch coal specimens, especially those in stronger coal, in non-hydraulic actuated testing machines was reminiscent of his description of those pillar bursts or bumps.

Jan 1, 1971

By G. R. Hart

The expected 1990 Clean Air legislation is providing electric utilities with a series of challenges and decisions as the utilities prepare strategies to comply with the resulting regulations. This paper addresses the strategy development of a coal-based utility --the legislation, the process used, the fuel issues, the options available, and the decisions to be made.

Jan 1, 1991

By F. Calizaya

This paper explains and discusses a computer program developed to determine the ventilation design parameters for complex auxiliary ventilation systems such as those found in the construction of long excavations with multiple headings. The program is based on the principle of partitioning the system into segments of finite length, and formulating and solving the resulting networks recursively. The application of the program is illustrated by the detailed solution of an auxiliary ventilation system proposed for the Exploratory Studies Facility (ESF) at the Yucca Mountain project, Nevada.

Jan 1, 1994

By Mohan Dutt

This paper is concerned with applied platinum resistance thermometry which involves many considerations absent in precision thermometry. The historical development of the Callendar-Van Dusen Equation which describes the resistance- temperature relation of pure platinum is discussed. The advantage of using platinum resistance temperature sensors over thermocouples is described, and the improvements in design and construction of these sensors that have come about in the past few years are discussed. Integral and remote bridges that convert resistance changes into voltage together with signal conditioning techniques and equipment for voltage or current signals are described. Errors encountered in temperature measuring schemes and methods to reduce these errors are summarized.

Jan 1, 1969

By J. R. Patts, J. P. Rider, J. A. Organiscak, A. B. Cecala

"The U.S. National Institute for Occupational Safety and Health completed a 15-month study at an underground limestone mine crusher booth that evaluated three research parameters: (1) the effectiveness of a filtration and pressurization system for improving the air quality inside the operator booth, (2) the relative effectiveness of ? > 99 and ? > 95 experimental prototype filters in the system, and (3) the performance of three different cab pressure monitoring devices. The protection factor was quantified monthly using particle counters in the respirable dust range of 0.3 to 1 µm particle size, and gravimetric dust samples were gathered at the beginning and end of the overall study. Under static (closed-door) conditions, the filtration unit offered a gravimetric calculated protection factor between 10 and 31, depending on the filter type and loading condition. The monthly particle counting analysis shows that the ? > 95 filter offers a protection factor nearly five times that of the ? > 99 filter, where n = 15 samples. The booth pressure monitors were tested and proved to be a valid indicator of system performance over time. IntroductionDesigned and installed correctly, enclosed cabs, operator booths and control rooms offer mine workers protection from noise and physical hazards, such as flying rock and debris, as well as a more comfortable environment in regards to temperature and humidity (Organiscak et al., 2016). While it is easy to quantify the operation of a cab’s air-conditioning unit by measuring the temperature, or observe whether the cab offers protection from flying debris, it is somewhat more difficult to quantify its performance in reducing respirable dust hazards.The U.S. National Institute for Occupational Safety and Health (NIOSH) has been conducting applied research to improve the air quality inside the enclosed cabs of mobile equipment, resulting in the mathematical modeling of enclosed cab filtration systems (Organiscak and Cecala, 2008). The same principles that govern the performance of filtration systems on mobile equipment are applicable to stationary enclosures such as operator booths and control rooms (Noll, Cecala and Hummer, 2015). While stationary enclosures are similar to mobile cabs, the work area can be significantly larger. Workers in booths and control rooms also tend to stay within the enclosure for a greater percentage of the day as opposed to workers on mobile equipment who enter and exit frequently."

Jan 1, 2018

By Simon Strong, Tim Brown, Luis Ignacio Sanz Vivanco

"One of the most significant technical and practical challenges facing the tunnel construction team on the Legacy Way road tunnel project in Brisbane, Australia was how to erect the pre-stressed precast concrete slabs to form the smoke duct in the tunnel boring machine (TBM) tunnels. An essential part of the tunnel ventilation system, the smoke duct, extends the full length of the 4.6km long twin, two lane tunnels. The vast majority of the tunnels (approx. 4.3km) were constructed using two 12.4m diameter double shield TBMs. The refurbished Herrenknecht machines broke several world records on the way to completing the tunnel excavation works in just over nine months. With the excavation complete the focus turned to solving the complex civil tunnel fit out challenges. A key component of the civil fit out of the tunnels was constructing the smoke duct in the TBM tunnels which was designed as a precast solution. The slabs which each measure 8.62m long by 2.0m wide by 200mm thick and weigh close to 9 tonne need to be erected above cast in situ corbels whilst other tunnel finishing works continue. The space proofing clearance offered by the design to the support corbels below and the precast segmental lining above was in the order of only 100mm. This paper details the events of how the Transcity JV tunnel fit out team, comprising some of Europe and Australia’s leading tunnel construction specialists, drew upon the global strengths of the existing JV member companies and the global reach of leading TBM manufacturer Herrenknecht to develop an innovative system to solve this challenging problem. This globetrotting story, which starts in Australia, visits Europe and mainland China before returning to Brisbane where it all began."

Jan 1, 2016

By Rosa Malena Fernandes Lima, Kerollan da Silva Ramos, Joyce de Assis Silva, Geriane Macedo Rocha

This study evaluated the effects of collector type amide-amine compared with those of conventional etheramine acetate (both cationic collectors) on the surface properties of quartz and hematite. An examination of certain properties of the reagents indicated that the new collector amide-amine has CMC (critical micelle concentration) and pKa values (100 mg/L and 8.2, respectively) significantly lower than those of etheramine (800 mg/L and 9.4, respectively). Microflotation tests showed that the recoveries of quartz with amide-amine in all the concentrations tested were higher than those with etheramine. This is attributed to its lower CMC and pKa values. The selectivity window between quartz and hematite flotation using amideamine was higher at pH 10.5 (approximately 80% for 5 mg/L). Therefore, the use of starch is not necessary in siliceous itabirite flotation by amide–amine collector. Zeta potential measurements and infrared spectra reveal that the adsorption of amide-amine collector on quartz surface occurs mainly by electrostatic attraction. Considering the better collectability of amide-amine for quartz flotation and lower adsorption affinity for hematite surface than etheramine, the amide-amine is a promising collector to be used in reversal iron ore flotation.

Jul 30, 2021

By Zoheir Khademian, Gabriel S. Esterhuizen, Morgan Sears

Based on the 2010-2019 Mine Safety and Health Administration (MSHA) accident report database, 91% of reported ground control accident in the US longwall mines were caused by gateroad roof instability. This can be related to the significant changes in loading conditions that gateroads are subject to from the development to the longwall abutment loading phases, combined with the thinly bedded shale roof, found in many US longwall coal mines. One of the challenges in designing efficient support systems is to understand the roof instability mechanisms along with support-roof interactions under this complex loading condition. Field monitoring of roof displacement and stress changes coupled with detailed analyses using numerical models are well-documented techniques to study the causes of roof instabilities. However, traditional modeling techniques require additional calibration to simulate delamination and buckling of shale roof, one of the main roof instability mechanisms in longwall mines. One alternative modeling technique is the UDEC Bonded Block Method (BBM) where bedded roof and support interactions can be explicitly captured. This paper presents the development of a BBM model of a longwall entry at a 180 m depth of cover with a three-entry gateroad layout along with roof extensometer monitoring results. The models are validated against the monitoring data, showing the potential for BBM numerical models capturing the complex roof and support system interactions to assist with optimizing gateroad layouts and support systems.

By Stewart R. Wallace

In the spring of 1959 while visiting the offices of the US Geological Survey (USGS) in the Denver Federal Center, I had a chance encounter with Paul Theobold, a former but, at that time, casual associate. Paul mentioned to me the results of his work on stream sediment geochemistry (Theobold and Thompson, 1959). Using panned concentrates, Theobold and Thompson had discovered a tungsten anomaly in Clear Creek and followed it upstream to its source on Woods Creek, a small tributary to the West Fork of Clear Creek. The specific source was a debris cone about 0.8 km (0.5 mile) upstream from the mine yard at the Urad molybdenite deposit. Because of the genetic and zonal association of tungsten and molybdenum at Climax, I found this very interesting. Accordingly, I related this information to Robert Henderson, general manager of western operations for Climax, and asked his permission to do some follow-up work. He, in turn, telephoned Frank Coolbaugh, the president of Amax, telling him of my interest and saying that, "Climax would take care of it." On my first visit to Urad, my companions (Dave Jonson, Bruce MacKenzie, and Dick Baker) and I were confronted by a "Cousin Jack" caretaker who made up for his diminutive stature by a "pistolover" that hung down almost to his knee and by a watchdog that was one-half wolf and one-half mean sled dog. We retreated discretely to Clear Creek and then climbed up the "back" side of Red Mountain by separate routes, across the ridge crest, and part of the way down the "front" side, sampling as we went. Although much of the ground was covered with snow, we found lots of puzzling but friendly looking rocks and the geochemical results were interesting. A geologic map of central Colorado showing the location of the Urad-Henderson and Climax deposits is shown in Fig. I.

Jan 1, 1991

By Lim Thi Duong, Du Duy Bui, Thuat Ngoc Pham, Chuc Ngoc Pham, Que Anh Nguyen, Hoa Anh Bui, Chi Thi Ha Nguyen, Hoan Thanh Nguyen, Bac Quang Nguyen, Kien Trung Nguyen, Dung Trung Doan, Nhiem Ngoc Dao

The microstructures and kinetics of a rich iron ore ( TFe = 65.84%) of Na Rua mine, Vietnam, used for the iron production were investigated in this study. Thermal behaviors of iron ores were well-examined by heating microscopy, thermogravimetric analysis, and differential thermal analysis. After being pelletized and then oxidatively fired at 500–1200 °C for 2 h, the pellets fired at 1200 °C (P1200) displayed a hard and dense structure with a decent compressive strength of 317.9 kg/pellet whereas those fired at 500 °C (P500) had a soft and spongy structure. The reduction of iron pellets conducted in a flow of a 60–100% CO2/ Ar gas mixture at 900–1100 °C showed significantly higher efficiency than the reduction using coal. The spongy pellets showed superior performance for the reduction in the CO/Ar gas mixture compared to the dense ones, compatible with the production of sponge iron. When mixed with an amount of coal, P1200 designed for iron production in the blast furnace demonstrated an impressive reduction activity compared to P500 and previous studies. The kinetics of pellet reduction was determined by the diffusion of substances through the solid product layers having the mathematical model of 1 − 2 3 f − (1 − f )2∕3 = kt . The microstructures of pellets during the oxidative firing and reduction were also examined by X-ray diffractometry; scanning electronic microscopy; energy-dispersive X-ray spectroscopy; and Brunauer, Emmet, and Teller method.

Jun 7, 2022

By Luisa Alfieri, Giorgio Fantauzzi, Sergio Notarianni, Spencer Cavagnet, Alessandro Damiani

"The new tunnels of the Copenhagen ""Cityringen"" will be excavated, at Kongens Nytorv square, crossing over the existing M1 and M2 metro lines. After the crossing, the tunnels will underpass the historical building of the Magasin du Nord and adjacent masonry buildings, with a minimum tunnel cover of about 4.5 m. The tunnels have an internal diameter of 4.9m and are being excavated through earth pressure balanced Tunnel Boring Machines in mixed face.The Magasin du Nord estate is characterized by a very complex structure, with different blocks built in different times. An assessment of the condition of the building and its sensitivity to tunnellinginduced ground movements has been conducted through a fully coupled soil-structure interaction analysis; based on the results of this analysis, mitigation measures have been designed.INTRODUCTIONThe Copenhagen Metro Cityringen is expected to be running in July 2019 and will consist of two single tracks in a twin tunnels, each approximately 16 km in length, for transporting up to 243,000 passengers on an average work day. The Cityringen includes 17 underground stations with island platforms, 4 crossover facilities and 3 construction and ventilation shafts. The tunnels is being excavated using earth pressure balanced Tunnel Boring Machines and have an internal diameter of 4.90 m.The intersection with the existing M1 and M2 metro-line will take place at Kongens Nytorv and at Frederiksberg. According to the design alignment, in Kongens Nytorv the new tunnels will pass over the existing M1 and M2 ones; as a result of this, the tunnels will underpass the historical building of the Magasin du Nord and the adjacent masonry building hosting a Mc Donald’s with a minimum cover of about 4.5m.In the framework of Risk Assessment for sensitive buildings, the effects of tunneling-induced ground movements on the Estates ØS0437 (McDonald’s building), ØS0428 (Magasin du Nord) and ØS0004 (Hviids Vinstue) were evaluated. To achieve this goal a fully coupled soil-structure interaction has been considered and the entire excavation process has been reproduced in a 3D model where the abovementioned buildings have been modeled. In this way, a risk assessment analysis was performed evaluating directly the effects of the excavation in terms of settlements and variations of the internal forces as far as the excavation process proceeds. In figure 1, a picture of the construction of Kongens Nytorv station, with Magasin du Nord and Mc Donald’s building on the background, is presented."

Jan 1, 2016

By John Berney-Ficklin

Large scale grinding mills can reduce both capital and operating costs for concentrators. These mills can be effectively used, but they must be free from design and manufacturing deficiencies if they are to reach their full potential and avoid costly downtime. This paper presents the evolution of today's complex grinding mill specifications and discusses the most important items to look for when buying new equipment. It emphasizes the need to monitor specification requirements during design and manufacture. It also discusses the growing trend to have grinding mills fabricated in overseas plants, and the importance of recognizing this when preparing specifications.

Jan 1, 1987

By Stanley J. LeFond

The Republic of Botswana, one of the newer countries of southern Africa, attained independence on September 30, 1966. It covers an area of about 225,000 square miles (582,000 square kilometers) which makes it slightly larger than France, or slightly smaller than Texas. It is bounded by Zimbabwe, the Republic of South Africa and Namibia, including the Caprivi Strip. Angola and Zambia are close neighbors. (Map 1). Botswana lies at the center of the southern African plateau at a mean elevation of 3,300 feet (1,000 m). It is a natural habitat for most species of African fauna. The rolling sands and extensive grasslands of the Kalahari Desert cover the southwest. The climate is sub- tropical. Summers, although tempered by north- easterly breezes, are hot, but mean maximum temperature seldom rises above 100°F (38°C). Winters are dry with wide temperature variations, which often give rise to frosts.

Jan 1, 1981

By Aimee A. Woolsey

Enterprise Unmanned Traffic Management is a holistic system concept evolving from technological developments in radio frequency where dynamic tracking can be added into current and emerging platforms. This is done through inexpensive RF sensors capable of real-time and cooperative, non-GPS tracking enabling digital visualization of assets, including unmanned aerial systems (UAS). The RF sensors are low size, weight, and power (SWaP), creating efficiencies in energy and material consumption while transmitting positions in real-time and at long ranges. Multiple UAS and other unmanned vehicles can be visualized for risk mitigation in operations,

Oct 17, 2022

By Brian Fulcher, Matthew Bartlett, Jarrett E. Carlson

This paper discusses the challenges to complete the construction of two large underground Metro stations and connecting tunnels in the Tren Urbano system. The completion work includes the installation of specialized mechanical and electrical systems, extensive architectural finishing as well as coordination with systemwide power and controls installed by others. A unique feature of this project was the simultaneous design and construction of the structural/civil/architectural/mechanical/electrical works by KKZ separately from the power and control systems under the management of the Owner, its consultants and other contractors. Completion of this project comes after almost six years of continuous design and construction in a dense urban environment. The project was confronted by many challenges that could only be met with the combined efforts of the Joint Venture team in close cooperation with the Owner and its System wide Contractor. This paper will also address many of the major design and construction changes implemented to suit the Owner’s requirements.

Jan 1, 2003

By P. Schmäh

Nowadays, small diameter tunnels are increasingly considered in pipeline projects as an alternative for sensitive crossings or when soil conditions limit the use of conventional pipeline installation methods like HDD. Safety concerns play a key role, especially for inner-city installations. Pipe jacked microtunnels and small segment lining tunnels can serve as casing tunnels if access is required during construction for the change of cutting tools in challenging ground conditions or for maintenance of the pipeline in operation. Small diameter tunneling solutions offer a high degree of flexibility for alignment design in terms of geology, length and radius.

Jun 13, 2021

By William V. Robinson

The Iron Ore Company of Canada mines, processes and ships crude iron ore, concentrate and pellets from the rich ore bodies of the Labrador Trough area in the extreme north-eastern part of Canada, some five hundred miles from Montreal (see figure 1). There are three main sites of activity. At Schefferville, approximately 12 million tons a year of crude ore (chiefly limonite) are mined, crushed, screened and shipped to Sept-Iles. At Labrador City, 40 million tons of specular hematite are mined annually for processing into 17 million tons of concentrate. Of this, 9 million tons are converted into pellets. All product 1s shipped to Sept-Iles. At Sept-Iles, on the north coast of the St. Lawrence, a six million ton per year concentrator and pellet plant process much of the Scheffervllle ore into high-grade pellets. Also at Sept-Iles are the company's administration offices stockpiles and shipping facilities. The Terminal facilities can berth and load a 250,000 ton bulk carrier at 19,000 tons per hour.

Jan 1, 1975