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By Joseph Kuti

Longwall mining is the term used for the underground extraction of a wide and deep panel of coal. Such a panel may be blocked out by one or more entries on either side ("head" and "tail") of a longwall face. If all the entries are pre-driven, the panel extraction is termed longwall retreat mining. With one exception, all the longwall faces in the United States are of this type. (1) prior to the general decline in the rates of production with Continuous Miners, the development of the multiple entries generally kept ahead of the longwall extraction rate. This is no longer the case: longwall extraction rates far exceed the rate of development. In addition to this problem, in newly established mines, the development of a haulage and bleeder system based on multiple entries results in a lead-time of three years or more before longwall mining can be applied. This is one reason why earlier projections and much of the optimism attached to longwall mining as a principal "savior" in the energy crisis should be viewed with some caution.

Jan 1, 1978

Editor's note: Biographical information about Ihor Kunasz, president, Newmont Uzbekistan, can be found in the February 1998 issue of ME, page 94 and in the May 1996 issue, page 92. Your personal assessment of the minerals business. Gosh! When I think about what has happened to the minerals industry over the past 27 years that I have been a member of SME! There have been fundamental structural changes in the industry. And I think that SME has been quite successful in coping with these changes as well. There has been a reorientation in how the minerals industry does business. It used to be called rationalization. Today we call it reengineering. In addition, the minerals industry has become more complex and more global. Shareholders have become more vocal and demanding in the management of the business, asking for protection of their shareholders' value. In the 1980s, a fundamental change was precipitated by a merger and acquisition fever in all industries, including the minerals industry. Raiders such as T. Boone Pickens put enormous demands on companies that, in turn, had to spend substantial management time to fend off the raiders. This resulted in a major restructuring of the mining houses. Today, for example, Anaconda, Kennecott and Amax are only historical names.

Jan 1, 1998

By Bhaskar B. Thapa, Michael T. McRae, Johannes V. Greunen

This paper describes the preliminary design of the fourth bore of the Caldecott Tunnels along State Route 24 in Oakland, California. The paper focus is on two major aspects of the project: initial support system design and seismic design. The initial support system was designed based on the New Austrian Tunneling Method (NATM).NATM provides the required flexibility to accommodate the variable ground conditions in the weak, folded, and faulted rock along the alignment. The seismic design provides a final lining system that meets serviceability requirements for a 1,500 year seismic event with an estimated peak ground acceleration of 1.2g.

Jan 1, 2007

By Thomas Novak, Sampurna Arya

Controlling dust generation and keeping it below permissible limits to meet federal dust standards at the working face of a roomand-pillar coal mine is a challenge for a mine operator. With the recent changes in federal dust regulations requiring lower worker exposure, maintaining compliance has become increasingly difficult. The current most effective practice of dust control at a continuous miner face in an underground mine is the use of a flooded-bed scrubber. A study carried out by the National Institute for Occupational Safety and Health (NIOSH) indicated that a flooded-bed scrubber could achieve cleaning efficiencies between 58 and 90%. But, the operation of such a system is maintenance intensive. The flooded-bed scrubber screen becomes clogged with dust particles and requires frequent cleaning to maintain performance. However, the dust control issue is not solely a mining industry problem. Other industries face similar issues. The University of Kentucky collaborated with Toyota Motor Manufacturing on the development of a novel wet scrubber, called the vortecone scrubber, for capturing oversprayed paint particles in automotive paint booths. The vortecone scrubber achieved a cleaning efficiency of 99% and required minimal maintenance. This study aims to assess the ability of this vortecone scrubber to capture respirable dust in an underground coal mine. The paper presents the results of computational fluid dynamics (CFD) modeling of this vortecone scrubber. It discusses the effects of air quantity and dust particle size on the performance of the scrubber.

By D. S. Yantek, C. B. Brown

The mining industry is beginning to implement lithiumion batteries (LIBs) to power mine utility vehicles (MUVs) and rubber-tired mantrips (RTMs). However, the ability of LIBs to withstand the harsh conditions for these applications has not been rigorously evaluated. Concerns with the use of LIBs in the mining environment will be discussed including the effects of mechanical shock and vibration, temperature extremes, and moisture exposure. This paper will discuss adverse effects of the mining environment on LIBs and provide an overview of scientific gaps associated with the environmental susceptibility of LIBs used on MUVs and RTMs.

Feb 1, 2024

By D. J. Pyra, J. Kudelko, Korzekwam W.

Polkowice region (Lower Silesia, Poland) is an area, where the copper mining activity started about 40 years ago and new technologies were applied. There are 3 underground mines, 3 processing plants, tailings pond (the biggest one in Europe), pipelines for flotation waste transport, railways. Although new technologies were applied during the copper ore exploitation, the environment in this area were polluted mostly by dust containing copper, lead, zinc and arsenic. Estimated values of heavy metals in polluted soils were compared to the natural contents of this metals. The geochemical background for Polkowice area was defined. The pollution zones occur around mining facilities. Copper ore exploitation and processing is planned for the next 20-40 years depending on market situation. After mines and other facilities closing the most important problem will be sustainable development of this area. To evaluate the scope of revitalization activities the analysis of recent soil environment condition will be necessary as well as forecasts for pollution migration. Geostatistic methods used also in mining will be very helpful for this task.

Jan 1, 2005

By MAHESH SHRIWAS, CHRISTOPHER PRITCHARD

Ventilation monitoring and control in mines are becoming an integral part of day-to-day activity for maintaining the health and safety of miners. This paper evaluates potential real-time monitoring solutions for detecting and reducing diesel particulate matter (DPM), mine fires and dust in situ and examines the state-of-the-art use of ventilation monitoring and control in underground mines for detecting and reducing air contaminants to acceptable regulatory limits. In this study, relevant documents, including research papers, trade publications and manufacturer website information, are reviewed to identify research gaps. This paper also includes evaluations of contemporary sensors (airflow, gas, dust and silica), control system and software technologies, data transport systems, the Industrial Internet of Things (IIoT), ventilation network simulators and control devices to identify potential health and safety research gaps. Examples of some mines in Canada, Australia and the United States that have been using ventilation monitoring and controls are included as well. Overall, this review identifies multiple challenges and research gaps in applying mine monitoring and control systems that could be the focus of future research, offering potential improvements to miner safety and health and financial benefits.

By Shanming He, Jinliang Wang, Xiaoming Wang, Chunfa Liao

Large amounts of manganese-rich slag were generated from smelting low-grade manganese ore containing high iron and high phosphorus in electric furnace or blast furnace, which contain 25–40 mass% Mn. This paper describes an efficient hydrometallurgical process for the utilization of high manganese slag instead of conventional usage of pyrometallurgical route for manganese recovery. Pressure acid leaching of manganese-rich slag using air as pressurized gas is studied systematically. The effects of mass ratio of manganese-rich slag to pyrite, concentration of sulfuric acid, leaching temperature, partial air pressure, leaching time, and liquid-solid (L/S) ratio on the separation of manganese with other main impurity components were investigated comprehensively. Under the following optimal process conditions, weight of manganese-rich slag powder,100 g; mass ratio of manganese-rich slag to pyrite, 20:1; sulfuric acid concentration of 140 g/L; air pressure of 0.6 MPa; leaching temperature of 140 °C; leaching time of 1 h; L/S of 7:1; ore size of 75–80 μm; and stirring rate of 600 rpm, the extraction rate of Mn reached 94%, and the dissolution percentage of Si, Al, and Fe are as low as 2%, 6%, and 10%, respectively. The leaching slurry presented a good solid-liquid separation characteristic. The silicic acid formed during sulfuric acid leaching manganese silicates was converted to filterable dehydrated SiO2 particles which precipitated in the residue under the condition of higher temperature with higher pressure. The effect of adding pyrite may be to reduced iron ions and decreased the output of iron hydroxide colloid and also reduced MnO2 to manganese sulfate in sulfuric acid leaching. Thus the formation possibility of colloid such as silica gel and iron hydroxide was decreased, and higher yield of manganese sulfate could be achieved.

By Shanming He, Jinliang Wang, Xiaoming Wang, Chunfa Liao

Large amounts of manganese-rich slag were generated from smelting low-grade manganese ore containing high iron and high phosphorus in electric furnace or blast furnace, which contain 25–40 mass% Mn. This paper describes an efficient hydrometallurgical process for the utilization of high manganese slag instead of conventional usage of pyrometallurgical route for manganese recovery. Pressure acid leaching of manganese-rich slag using air as pressurized gas is studied systematically. The effects of mass ratio of manganese-rich slag to pyrite, concentration of sulfuric acid, leaching temperature, partial air pressure, leaching time, and liquid-solid (L/S) ratio on the separation of manganese with other main impurity components were investigated comprehensively. Under the following optimal process conditions, weight of manganese-rich slag powder,100 g; mass ratio of manganese-rich slag to pyrite, 20:1; sulfuric acid concentration of 140 g/L; air pressure of 0.6 MPa; leaching temperature of 140 °C; leaching time of 1 h; L/S of 7:1; ore size of 75–80 μm; and stirring rate of 600 rpm, the extraction rate of Mn reached 94%, and the dissolution percentage of Si, Al, and Fe are as low as 2%, 6%, and 10%, respectively. The leaching slurry presented a good solid-liquid separation characteristic. The silicic acid formed during sulfuric acid leaching manganese silicates was converted to filterable dehydrated SiO2 particles which precipitated in the residue under the condition of higher temperature with higher pressure. The effect of adding pyrite may be to reduced iron ions and decreased the output of iron hydroxide colloid and also reduced MnO2 to manganese sulfate in sulfuric acid leaching. Thus the formation possibility of colloid such as silica gel and iron hydroxide was decreased, and higher yield of manganese sulfate could be achieved.

By Joel Darmstadter

The position of the coal industry in America’s fuel and power picture remains one of prime importance. Measured in Btu terms, the industry is the country’s leading energy producer and an important exporter. Foreign coal sales yield annual proceeds of about $4 billion. Coal’s one-fifth share of the nation’s energy consumption is nearly as high as that of natural gas. Coal is the electric utility sector’s principal fuel supplier. It accounts for about55% of the electricity generated at power stations.

Jan 1, 1999

By M. Leslar

Slope monitoring has been an important issue in static terrestrial lidar for some time. Several solutions for monitoring the progress of a slide have been devised over the years. All of these solutions have required users to be in the field operating the lidar equipment. This paper presents a new system developed using the Optech ILRIS-HD or ILRIS-LR lidar and the scripting language of PolyWorks to produce an autonomous slope monitoring system. This system has proven invaluable in detecting and alerting mine workers to potential danger within their mine sites. It has already been deployed in two mine sites and is scheduled to be installed at a third.

Feb 27, 2013

By B. A. Comley

Over the past few decades a great deal of effort has gone into characterizing the effects of frother type and concentration in flotation using a variety of two-phase techniques. Whilst useful and informative, this research still does not assist in the selection of suitable frothers for three-phase industrial-scale froths. This paper investigates the effects of frother type and concentration in a three-phase industrial froth. The objective was to determine if progress could be made in terms of understanding the behavior of frothers in flotation and understanding how they affect the sub-processes occurring in the pulp and froth phases and, ultimately, the metallurgical performance of a flotation cell.

Jan 1, 2007

By İbrahim Çınar, Hakan Özşen

Mine workers in heavy and dangerous work are under several physical risk factors, for example temperature, humidity, noise, vibration, lighting and air velocity. Thermal comfort includes parameters such as air temperature, air humidity, air flow rate, radiant heat, metabolic rate and garment insulation. In this study, thermal comfort conditions were evaluated using thermal comfort indices defined as predicted mean vote (PMV) and predicted percentage dissatisfied (PPD) which were determined by measurements taken from an underground coal mine for approximately 100 days. Although the metabolic rate (light work) was kept at 2 met, it was found that predicted mean vote ranged between − 2.58 and 1.68. The predicted percentage dissatisfied index was found to reach 95%. According to the results, it can be seen that thermal comfort may have negative effects on occupational health and safety. The change in thermal comfort index values in the Soma Underground Coal Mine was investigated in detail and the reasons for the changes were determined. Furthermore, determining the optimal working environment for the mine workers was also an aim of this study.

By J. Kretschmann, A. Müterthies, T. Rudolph, C. Yang, P. Goerke-Mallet

Catastrophic failures of dams and tailing storage facilities (TSF) have triggered the development of integrated ground monitoring concepts for hazard assessment, risk management and public safety. These concepts are based on knowledge and expertise of persons technically responsible for TSF. The aim is to combine this implicit and explicit knowledge with the data of in-situ- and remote sensors. Risk management for TSF must include a comprehensive monitoring program that integrates data from ground based-, air-borneand satellite-based sensors. Researchers at Technical University Georg Agricola (THGA) in Bochum, and EFTAS, Muenster, Germany, are fusing a variety of sensor data to enhance the capability and performance of TSF monitoring to ensure public safety downstream of TSFs. This paper describes the variety of sensors implemented in numerous research projects. It gives an outlook in terms of planned satellite missions with innovative equipment like hyperspectral sensors. The implementation of the data of these sensors in the analysis will increase the understanding of spatio-temporal impacts of mining activities. Future opportunities are explained by a datacube approach.

Mar 2, 2022

By J. Wagner, P. Eger

Although lifetime estimates for sulfate reduction based on total substrate carbon typically range from 20 to 30 years, field and laboratory experiments showed that rates of sulfate reduction decreased over time as readily available organic material was consumed. When the rate of acid input exceeded the rate of sulfate reduction, alkalinity was removed from the substrate, pH decreased and metals increased. Output pH increased from 4 to over 6 after the system was shut down for several weeks and the rate of acid input was reduced. Successful long term treatment requires a design based on the input pH and the long-term organic decomposition rate.

Jan 1, 2001

By Garry Biles

The Eskay Creek Mine is a high-grade gold and silver underground mine in northwestern British Columbia. The mine started operations in late1994. For the first three years, ore was crushed to -50 mm(-2 in.), blended to satisfy smelter terms and shipped to smelters in Japan and Canada. Preliminary evaluations indicated that a complex metallurgical facility, requiring a large capital investment, would be required to recover the precious and other economic metals. So markets for raw ore were identified and underground mining and ore transportation operations began at a production rate of 300 t/d (330stpd).

Jan 1, 2000

By David Hatem, Michael Vitale, Joseph Gildner, Michael Roach, Fred Dunham

Dispute Review/Resolution Boards (DRB’s) are a highly successful dispute avoidance and resolution tool. In a joint effort between the UCA of SME and the Dispute Resolution Board Foundation (DRBF), the authors embarked on an informal assessment of the state of the DRB practice in the tunnel industry from the point of view of the Contractor, Owner, DRB Practitioner, and Attorney. The results of this assessment were presented in a panel discussion at the Rapid Excavation and Tunneling Conference (RETC) in June of 2021. This paper presents the results of that session with recommendations for further industry discussion and implementation

Dec 1, 2022

By Randy Vranes

Sophisticated information technology, quality management systems and a commitment to the environment has allowed Solutia’s Soda Springs phosphate mine and elemental phosphorus plant to reduce operating costs, improve product quality and contribute to the sustainable development of Idaho’s industrial minerals. Soda Springs background The Soda Springs phosphate mine and plant is a joint venture between Monsanto and its operating partner, Solutia Inc. The operation is based in southeastern Idaho in the Western Phosphate Field. The plant is located about 275 km (170 miles) northeast of Salt Lake City, UT and about 4 km (2.5 miles) north of the town of Soda Springs.

Jan 1, 1999

By Robert M. Semple, Harvey W. Parker

INTRODUCTION Two promising innovative tunnel support systems are being developed by the Civil Engineering Department of the University of Illinois. One of these is a lining which can be placed by a slipform located immediately behind and contiguous with a tunneling machine. Recent advancements in construction materials appear to provide the breakthrough required to make such a system feasible and practical. The lining material which permits this construction scheme is wire fiber reinforced concrete made with high, very early strength regulated-set cement. Parts I and II of this paper relate to this slipformed liner. Part I discusses the material and equipment required to install the liner. The "Extruded Liner System" (ELS) has been devised to place the lining. This ELS concept is briefly described and a tentative development program is outlined. In Part II, the physical properties and practical construction aspects of the liner material are discussed and a program for structural testing of 10-ft diameter prototype tunnel supports is presented. Part III contains descriptions of improvements to conventional steel-rib tunnel supports. It is shown that square tubular box sections are structurally superior to wide flange sections for complex loading conditions often encountered in rock tunnels. Analytical studies and tests on connections have been performed to evaluate their structural behavior. These are presented along with a program for comparative large-scale tests on horseshoe-shaped frames with a 10-foot span. This research is being conducted by the Department of Civil

Jan 1, 1997

By Zach Ahinga, Mike McRae, Dave Hopkins, Steve Klein

The San Vicente Pipeline project involves the construction of an 8-1/2 foot diameter water pipeline in an 11 mile long tunnel in San Diego, California. The tunnel will be excavated in extremely variable geologic conditions consisting of strong granitic and metamorphic rocks, weak sedimentary rocks, abrasive conglomerates, and mixed face conditions. This paper discusses the challenging geologic conditions and some of the key design evaluations for the project. Currently design work for the project has been completed and construction will be underway by mid-2005.

Jan 1, 2005