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By M. Menéndez

Enhanced gravity separation appears to be one of the most promising methods for processing all types of <200-µm coal feeds and tailings. Systems based on this technology are reviewed, and the results of investigations based on C900 Multi-Gravity Separator tests conducted to assess the treatment of <200-µm, extremely difficult-to-wash coal settling pond tailings are presented. Multi-Gravity Separator processing tests of ultra-fine tailings with a high clay particle size content (22.6% <10 µm and 60.1% <40 µm) and a 69.56% ash content show that this material can be effectively treated after desliming (<10 µm) of clay-size particles to produce a coal with a 20.6% ash at a separator combustible material recovery of 69.3%. Desliming is shown to be critical in reducing coal ash content and combustible material recovery. Similar improvements are anticipated in the recovery and separation pro-cesses for other enhanced gravity separation systems from the desliming of feeds. Although not a conventional form of treating Multi-Gravity Separator data, the existence of well-defined polynomial relationships based on the product of drum shake amplitude and shake frequency relative to product coal recovery, product ash content and yields at varying wash water flows is demonstrated. Low-amplitude and intermediate- to high-frequency bed agitation are shown to produce optimum ash reduction results.

Jan 1, 2007

By S. S. Peng

In dealing with the mining engineering problems, the traditional approaches of laboratory experimental simulations and/or analytical solutions are not very effective. Mainly because the field problems are too complex to be solved with a few simplified assumptions. Conversely it is also true that the experimental and analytical/ numerical models currently available are far from being able to model the actual cases. Under such conditions, the most effective mean of research into mining engineering problems is to combine the mine (field) investigations with laboratory and / or analytical modelings. It is with this concept in mind this research was initiated in 1973. &apos;The field investigations which began in the fall of 1978 consisted of mainly visiting the mines where surface subsidence monitorings had been or were being monitored and/or surface structural changes had occurred. From such visits, subsidence data were collected. A quick analysis of those data provided preliminary understandings of the characteristics of the surface subsidence parameters in the regions (1-5). Using those date, models of various types are being developed for subsidence prediction / control. So far, a total of 44 longwall subsidence profiles in 22 longwall panels and 10 room-and-pillar profiles in 5 room and-pillar sections have been collected. This paper summarizes the combined results published previously (1-5) and present the preliminary results of the predictive models developed.

Jan 1, 1982

By Don Phelps, John Hawley, David P. Field

In recent years observational techniques of tunneling have become increasingly popular methods to facilitate complex underground infrastructure projects. The traditional design and construction management practices developed in Europe have been adapted for application in North America to suit a more restrictive management and legal culture. This paper will discuss three recent projects, the San Diego Mission Valley East Extension, Washington Dulles International Airport People Mover, and the Seattle Beacon Hill Station and Tunnels, with the objective of identifying the challenges of applying observational tunneling methods to established contractual practices in North America.

Jan 1, 2005

By John L. Kaplin

The underground construction for the Phase I Combined Sewer Overflow(CSO) Project is on an impressive scale by any measure, appearing more so in a midsize city like Providence, RI. The Narragansett Bay Commission recently completed $350 mil-lion in construction to improve the water quality in Narragansett Bay. This project included a number of serious challenges, delays, and disputes. Looking back on this complex project completed within budget, it is hard to consider the work as anything other than a success. Along the way, this outcome did not always appear certain.

By L. Alan Weakly

Global warming is a political reality in the United States today. The actual impact of the continued utilization of fossil fuels is not known and is open to debate. However, the growing concern about the continued use of these fuels is problematic. There are technologies available to us today that would permit America to meet its future energy demand and not contribute to global warming. The inconvenient reality is that fossil fuels cannot completely be replaced with energy conservation and the use of wind, solar, hydroelectric, geothermal and nuclear energy. The connection between the greenhouse effect and global climate change was first identified by physicist John Tyndall in the 1860s. To prove the greenhouse hypothesis, Roger Revelle and his research team started measuring carbon dioxide concentrations in the earth?s atmosphere in the early 1960s (Becker, 2007). With the rising concern about global warming, scientists throughout the world have been obtaining surface and air temperature data. Scientists have also been comparing CO2 concentrations found in glaciers throughout the world with theorized annual temperatures. Data for both dates back 1,000 years. Armed with this data, many nations of the world and the United Nations Intergovernmental Panel on Climate Change (IPCC) have concluded that climate change is a reality. The IPCC also concluded that this climate change is the result of mankind?s consumption of fossil fuels and that catastrophic consequences will occur on a

Jan 1, 2008

By Steve Kral

Good times make for happy miners. And the past few years have seen a lot of smiling mining engineers, geologists, metallurgists, corporate executives, analysts, investment bankers and shareholders. And nowhere was that more evident than at the 74th Prospectors and Developers Association of Canada’s (PDAC) annual meeting. The meeting, held in Toronto March 5-8, attracted a record 14,500 people. Of those, the PDAC said attendees came from an estimated 100 countries. And about 40 countries sent national delegations to the meeting. Argentina, for example, sent nearly 100 people. The PDAC meeting has always been a event where companies and individuals can get a look at numerous properties in all parts of the world that could potentially become major mines. And through the many receptions, hospitality suites and just sitting in the local restaurants and taverns, deals are usually made.

Jan 1, 2006

By M. Okido, W. Wei, L. Chai

The kinetics on the growth of Thiobacillus ferrooxidans was studied by use of series piezoelectric quartz crystal ( SPQC ). Arsenic ioninhibits the growth of Thiobacillus ferrooxidans, which is consistent with the previous results by other measuring method. This further demonstrates that the SPQC can monitor the chemical activity of the growth of Thiobacillus ferrooxidans. Cupric ion accelerates the growth of Thiobacillus ferrooxidans. The mechanism was discussed, it was considered that copper promotes the protein enzyme of Thiobacillus ferrooxidans, rustic yanin, to form over the range of cupric ion concentration studied. There action order of cupric ion in accelerating the bacterial growth is 0.067. The growth of Thiobacillus ferrooxidans is dependent on temperature, the apparent reaction activation energy decreases from25.56 kJ / mol to 18.32 kJ / mol because of the addition of 10 mg / L Cu(II) to the bacterial growth solution of pH 2.0 at initial inoculum of 10%.

Jan 1, 2000

By G. Aggistalis, N. Kazilis, C. Rawlings, N. Rachaniotis, S. Raptopoulos, M. Knights, R. Game

The Egnatia Odos (Odos meaning road) is one of Greece’s largest ever highway construction projects and one of Europe’s most important. The Highway will assist in the connection of the Greek Ionian/Adriatic Coast with Turkey and the Black Sea reviving an historic Roman alignment “Via Egnatia” connecting Rome to Constantinople (now Istanbul). There are 74 twin tunnels (60 bored and 14 cut-and-cover) with lengths ranging from 160 m (175 yd) to 4,600 m (5,031 yd) and 100 m (109 yd) to 270 m (295 yd),respectively. The complex geology and resulting physical geography have had a major influence on both the design and construction of these tunnels. This paper describes the management, design and construction challenges of these numerous tunnels.

Jan 1, 2005

By M. R. Shahan, C. E. Seaman, Mischler S. E., T. W. Beck

"Float dust deposits in coal mine return airways pose a risk in the event of a methane ignition. Controlling airborne dust prior to deposition in the return would make current rock dusting practices more effective and reduce the risk of coal-dust-fueled explosions. The goal of this U.S. National Institute for Occupational Safety and Health study is to determine the potential of open-air water sprays to reduce concentrations of airborne float coal dust, smaller than 75 µm in diameter, in longwall face airstreams. This study evaluated unconfined water sprays in a featureless tunnel ventilated at a typical longwall face velocity of 3.6 m/s (700 fpm). Experiments were conducted for two nozzle orientations and two water pressures for hollow cone, full cone, flat fan, air atomizing and hydraulic atomizing spray nozzles. Gravimetric samples show that airborne float dust removal efficiencies averaged 19.6 percent for all sprays under all conditions. The results indicate that the preferred spray nozzle should be operated at high fluid pressures to produce smaller droplets and move more air. These findings agree with past respirable dust control research, providing guidance on spray selection and spray array design in ongoing efforts to control airborne float dust over the entire longwall ventilated opening. IntroductionCoal mining processes produce airborne dust that naturally deposits on the floor, roof and ribs of mine airways. These fine dust particles, termed float coal dust when smaller than 75 µm in diameter, are deposited in the return entries of coal mines and can be reentrained by pressure waves induced by methane-air explosions (Rice et al., 1911; Nagy, 1981; U.S. National Institute for Occupational Safety and Health (NIOSH), 2006). These particles are also those most likely to participate in coal-dust-fueled explosions, which can potentiate and propagate explosions resulting in extensive damage. In order to meet compliance requirements of at least 80 percent incombustible content in the composition of material deposited in mine entries (U.S. Mine Safety and Health Administration (MSHA), 2016), coal mines apply an inerting agent, specifically, rock dust (Harris et al., 2009). Should methane be present in the mine atmosphere, the required fraction of incombustible content is further increased by 0.4 percent for each 0.1 percent methane. The removal of airborne float coal dust (AFCD) prior to deposition is an approach intended to make current rock dusting practices more effective by increasing the proportion of inert material to combustible material, resulting in a lower risk of coal-dust-fueled explosions."

Jan 1, 2018

By K. Zabrusky

Estimation of high grade epithermal vein deposits can present challenges in correctly representing the continuity of grade within an undulating structure. One solution to this problem is to use dynamic anisotropy to follow local variations in the strike and dip of veins. Dynamic anisotropy (D.A.) allows the search parameters to change block by block throughout the model to account for the local variations. Presented here is a study of a vein that changes orientation down-dip. A traditional resource estimate using one search ellipse orientation was performed. The resulting estimated grades did not accurately reflect those of the sample data. Using a search ellipse with an average value for the two distinct dips caused the grade estimation to be less representative than desired. Rather than performing domain-based analysis with different search ellipses, the issue was corrected by using Datamine Studio 3?s D.A. function. The 3D vein trend was used to estimate the dip and dip direction of the vein in each block. The resulting D.A.-estimated model follows the two dip trends of the vein. This software makes a previously tedious task faster, and allows for more accurate estimations.

Feb 27, 2013

By Z. Zhang, M. S. Gonzalez, M. de P. Bueno, P. Holopainen, S. Luukkanen

"Despite being a field of study that requires practical knowledge and experience, mining engineering education follows the same pattern in most mining universities around the world, consisting of theoretical courses and laboratory-based practical modules (Mischo, 2015). The possibility of having practical training in real mining conditions on actual mine sites or processing plants is limited, while the only contact that undergraduate students have with mining operations during their time of study is usually through shorttime internships or visits in the context of educational trips. Real integration between universities and the mining industry may be scarce, which does not help students to observe the actual processes and thus understand the whole picture of mining operations.Indirect practical training is now possible since that technology is shifting from mechanical to digital, and the use of virtual reality — in the context of Mining 4.0 — can provide additional experience to the learning process. However, virtual reality is limited to the visual impression and is also limited in actions (Binder et al., 2018). In any case, when there is not a proper pragmatic view of how the different disciplines link to each other, especially if there is a lack of communication, unfortunately the results could be seen at a later stage in the mines as a poor performance of professionals and workers.Another major challenge for educating specialists in the mining sector is that experimental mines suitable for practical education, where the skills and knowhow could be developed and/or enhanced, are rare worldwide. Such research and educational (R&E) facilities are practically former metal ore mines that have been transformed into experimental sites. Besides being limited in number, not all facilities of this kind serve both a research and educational purpose.An early example of asolely experimental mines is the Luossavaara-Kiirunavaara Mine site operated by LKAB in Sweden, where systematic research on rock mechanics and mining engineering was successfully carried out in the 1980s. As a result, the developed underground mining technology was applied in LKAB’s mines at a later stage. There have also been research mines within collieries such as the former Lake Macquarie Mine at New South Wales in Australia and the Zeche Tremonia Mine in Germany), but these are no longer in operation (Mischo, 2015)."

Oct 1, 2019

By T. Lamond, J. O. Costello

Marble is a preferred surfacing material in up-scale buildings. Its use increased in the 1870&apos;s with rising national wealth and declined in the 1950&apos;s when synthetic materials for these applications were developed. Natural marble is now limited to high-end domestic and commercial structures. Cultured marble is a paste of white marble dust and polyester resin cured in molds yielding fixtures of specific finished dimensions. Dyes incorporated at different stages in the mixing cycle mimic shades and veining of natural marble. This paper discusses the filler requirements for cultured marble production and reviews new techniques to cut and finish natural marble.

Jan 1, 1999

By G. W. Bonnell, D. A. Young, D. G. Genter

Through 1996 and 1997, CANMET and the Cape Breton Development Corporation (CBDC) conducted a project to study the Phalen Mine’s 7 East longwall ventilation network to help determine methane emission patterns that were having a negative impact on coal production. Increased methane emissions were primarily related to mining depth and were also affected by the influence of a large sandstone body located above the worked seam. The research included the installation of tube bundle systems to monitor waste (gob) methane and pressure differentials. The focus of this paper is on the novel use of tracer gas techniques that helped shed light on the performance of the ventilation system and in determining the methane migration paths in the waste.

Jan 1, 2001

By Steve Kral

"Liebherr, as most anyone involved with the global mining industry knows, is one of the world’s largest makers of mining and construction heavy equipment. The familyowned company has been around since the 1940s and, according to Stefan Heissler, by the end of next year, will employ about 44,500 people worldwide. Heissler is a member of the board of directors of Liebherr International AG.It all started for the Switzerland-based company when Hans Liebherr first recognized a need for heavy equipment in the construction industry, Heissler said. His first product, introduced in 1949, was the TK10, a mobile crane that, at the time, was a groundbreaking innovation to the heavy construction industry. From there, the company began its growth into a world-leading heavy equipment manufacturer that always relied on innovation.In October, Liebherr gathered a group of mining and construction magazine editors in Leoben, Austria to take a look at the company’s latest addition to the global mining and construction markets. On the mining side, Liebherr provided a demonstration of its T-236 100-t (110-st) haul truck and the PR- 766 50-st (55-st) crawler tractor. The one-day demonstration took place at the Erzberg iron mine near Leoben, where both machines are being proven.The Erzberg Mine, operated by VA Ersberg, has been in operation for about 1,300 years and is said to be Europe’s largest surface mine. It employs about 230 people and mines about 12 Mt/a (13,200 million stpy) of ore, producing about 3 Mt/a (3.3 million stpy) of fine-grained iron ore.T-236 rigid-frame truckThe new T-236 rigid-frame dump truck, with a diesel electric drive system, is Liebherr’s entry into the 100-t (110-st) class and is the first in this class with a four-corner, oilimmersed braking system. The haul truck was first introduced during the 2016 MinExpo in Las Vegas, NV. The unit has since successfully completed its testing phase and is currently in its first field operation trials at the Erzberg iron mine in Austria."

Jan 12, 2017

By J. L. Carr

Every year, severe injuries and fatalities occur when a miner is struck or pinned by a continuous mining machine, shuttle car, scoop or other piece of mobile mining equipment. Proximity detection systems offer a means to prevent these types of injuries and fatalities by sensing the presence of a miner and disabling machine motion. Although hundreds of these systems are installed and in use in operating coal mines, the influence that coal has on the electromagnetic fields associated with these systems has never been rigorously quantified. NIOSH researchers have conducted tests to measure whether the proximity of coal has a significant influence on a popular design of proximity detection system. The system tested utilizes a low frequency magnetic field generator that would be mounted on the mining machine. At the NIOSH Safety Research Coal Mine in Pittsburgh, researchers measured the performance of a simplified proximity detection system of this type first on the surface then underground at varying distances from a coal face. Analysis of these measurements shows that the presence of coal does not have a measurable impact. Disclaimer: The findings and conclusions in this report are those of the author(s) and do not necessarily represent the views of the National Institute for Occupational Safety and Health. Reference to specific brand names does not imply endorsement by the National Institute for Occupational Safety and Health.

Feb 27, 2013

By K. A. Larsen, J. L. Ariail, C. M. LaRosa

This article discusses the evolution of U.S. laws and policies towards environmental remediation at mine lands over the last 20years, the opportunities that these changes present for reuse, and the remaining challenges associated with community capacity for effective reuse planning and implementation. Emerging initiatives by the U.S. Environmental Protection Agency and Department of Interior for addressing these challenges are discussed.

Jan 1, 2004

Traditional fine grinding mills in mineral processing relied on the use of steel medium for particle size reduction. The successful development of the Isa Mill(a horizontal stirred mill with 3000 litres of net chamber volume and 1120 kW rated motor power)adopted a novel product separator design that has led to a major revision of medium use in fine grinding. The Isa Mill separator has also successfully operated with a wide variety of medium types such as silica sands, river gravel, smelter slag, run-of-mine ore fractions and steel shots, with size ranges from 0.5 to 10 mm. A great flexibility of the Isa Mill operations has been achieved for processing a feed as coarse as 120 um to a product as fine as 5 µm. This paper discusses the performance of two inert grinding media used in the Isa Mills in Mount Isa Mines of Australia for processing galena and sphalerite bearing ores to below 10 microns. They are the copper reverberatory furnace slag (CRFS)and the heavy medium plant rejects (HMPR). A methodology was also demonstrated for comparing the medium performance and for scaling up the Isa Mills from a 1.5-litre laboratory batch mill to a full scale 3000-litre mill.

Jan 1, 2000

By R. J. Kline

Most accidents are the result of risk taking. They can happen anywhere. Our coal industry categorizes accidents by type, occupation, commodity, age, every way you can imagine. We now know, how many were injured and when, for all the different types of accidents. We have ask ourselves many times, why are we having accidents, how can we stop the accidents and fatals in our industry? Present numbers and projections do not show that this will happen. Serious accidents can result in fatalities. Fatal accident can be prevented, and the coal industry can achieve zero fatalities. How soon this happens, depends on a great number of factors. I will discuss accidents and reasons for us having accidents in an attempt to get to the root causes. The historical perspective will be touched on, and the risk and analysis of accidents will be probed.

Jan 1, 2000

By H. Lyn Bourne

This marks the 15th consecutive year for this column. During 1995, readers were asked to supply royalty data for construction raw materials especially for states where none is available. The response was discouraging and royalty data are still missing for several states for either sand and gravel or crushed stone. Several readers have said that this article has merit but more new information is needed to justify its continuation. Several articles and pieces of news relative to mineral royalties appeared in the trade journals. R. Lee Aston (E&MJ, November, 1995, p. 16N) described South Australian royalties as amended by the government in1994. The royalty rate (a percentage) was lowered but the assessed value for minerals was raised and the current rate amounts to 20 cents//t (18 cents/st).

Jan 1, 1996

By R. Steele

In addition to compliance with government emissions and reporting requirements, mining and mineral processing companies are increasing energy efficiency to reduce costs and become more competitive in the global marketplace. One of the major obstacles to identifying opportunities for increased energy efficiency is the lack of readily available data on energy use, and more importantly the energy use linked to production data, that identify energy reduction opportunities. As well as energy reduction, mining and mineral processing companies often struggle with the prediction of energy use, and are often penalized for under or over forecasting. Once again, it is the lack of timely information that makes this prediction difficult. This paper looks at expanding the use of a Manufacturing Execution Systems by integrating with Energy Solutions. This will provide automatic, timely information, at a granularity that makes it easier to identify energy reduction opportunities, reduce energy costs, and better predict energy use in a mining and mineral processing operation.

Jan 1, 2011