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By J. P. Rider, T. W. Beck, J. A. Organiscak

"The National Institute for Occupational Safety and Health (NIOSH), Pittsburgh Mining Research Division (PMRD) has recently developed a series of models utilizing computational fluid dynamics (CFD) to study gas distribution around a continuous mining machine (CM) with various fan-powered flooded bed scrubber discharge configurations in an exhaust curtain working face. CFD models utilizing species transport model without reactions in FLUENT were constructed to evaluate the redirection of scrubber discharge toward the mining face rather than behind the return curtain. The study illustrates the gas distribution in the slab (second) cut. The following scenarios are considered in this study: 100% of the discharge redirected back towards the face on the off-curtain side of the continuous miner; 100% of the discharge redirected back towards the face, but divided equally to both sides of the machine; and 15% of the discharge redirected toward the face on the off-curtain side of the machine, with 85% directed into the return. These models were compared to a model with a conventional scrubber discharge where air is directed away from the face into the return. The models were validated based on experimental data and accurately predicted sulfur hexafluoride (SF6) gas levels at four gas monitoring locations. One additional prediction model was simulated to consider a different scrubber discharge angle for the 100% redirected, equally divided case. This paper describes the validation of the models based on experimental data and the gas distribution results of the CFD models. INTRODUCTION To control methane gas and dust concentrations on continuous mining operations, it is important to provide sufficient quantity of fresh air from the end of tubing or curtain to the active face. In this region, operating machine-mounted water sprays and fan-powered, flooded bed scrubbers can significantly increase the amount of airflow reaching the face [1-3]. However, when an entry is large, especially in higher coal seams, the water spray configuration and the scrubber capacity may not be adequate to maintain sufficient forward airflow to confine the dust cloud to the face. Dust can roll back toward the machine operator as a result [4]. Currently, several coal mines having negligible gas emissions in higher coal seams (2.4 to 3.0 m [8 to 10ft.] thick) with exhaust tubing systems redirect the scrubber discharge back towards the face in an effort to improve dust collection. NIOSH studied the redirected scrubber exhaust techniques for dust and gas control in a full scale CM gallery to assess its potential for industry-wide application [5]. For a CM face, previous studies have concluded that the behavior of gas and respirable dust is a complex process. The distribution/dispersion and transport of gas and respirable dust after they are liberated at the face are governed mainly by their mass properties, the movement pattern of the ventilation air, and interactions with the mining machine and water droplets created by the external water spray systems used for dust control [6-10]. To understand these behaviors in a complex CM environment and to evaluate the effectiveness of various control techniques, numerical modeling has become a necessary supplement to laboratory experiments and field studies."

Jan 1, 2017

The Forestry Reclamation Approach (FRA) specifies that the upper 1.22 m of material on the reclaimed surface should be left as uncompacted as possible to facilitate tree root growth. One of the main concerns about applying the FRA to steep slopes is that the upper 1.22 m of material could cause the reclaimed slopes to be unstable. Successful application of FRA on flat and rolling surfaces precipitated this investigation. Details of a field investigation conducted at a steep-slope mine are available in an earlier publication (Kumar and Sweigard, 2011). A total of 70 survey monuments were driven into the slope in a regular pattern to monitor slope movement. Quarterly surveys of the monuments were done to quantify any type of mass movement either horizontally or vertically. The methodology proposed for slope movement was verified using numerical models. Analytical models based on limit equilibrium technique and numerical models based on the finite element method were developed for slope stability analysis. The limit equilibrium analysis was done using Geo-Slope software following the Simplified Bishop Method. The finite element (FEM) numerical model was developed using the Plaxis computer program following the strength reduction technique. Two kinds of slope stability analysis were performed: first with the top 1.22 m of loose material and second without top loose material. Finally, the field investigation results were compared with stability analysis results. Both of these approaches showed that application of the FRA on steep slopes is not causing any significant instability problems that would not exist otherwise for overly steepened slopes. Keywords: Forestry reclamation approach, steep slope, slope movement, factor of safety

Feb 27, 2013

On Nov 1, 2007 House Resolution 2262 ? The Hardrock Mining and Reclamation Act of 2007 ? was passed by the U.S. House by a vote of 244-166. HR-2262, among other things, would impose a 4-per-cent royalty on existing mines with commercial production and an 8-percent gross royalty on all new claims. Not surprisingly, this possible new law was one of the hottest topics of discussion at the Northwest Mining Association?s conference that this year returned to Spokane, WA for its 113th annual meeting on Dec. 3-7. More than 1,800 delegates attended the conference that was held under the banner theme of ?Mining ?. For today and tomorrow.? Northwest Mining Association executive director Laura Skaer was one of many speakers during the three-day conference to respond to the threat to the industry posed by HR-2262 with a presentation titled ?Potential changes to the 1872 Mining Law.? In the presentation that she first unveiled at the Alaska Miners Association?s convention and trade show on Nov. 8, Skaer laid out a comprehensive list of problems with HR-2262. In addition to the association?s obvious concerns about the proposed royalty, Skaer noted that the bill includes a mine veto provision that would allow the Secretary of the Interior the authority to deny an operations permit to a project if the secretary determines that the operation would cause undue degradation to public lands and resources. Potential massive withdrawals from mineral entry are also included in HR-2262. Among the lands that could be off limits to miners under HR-2262 are wilderness study areas, areas of environmental concern and 23.6 hm2 (58.5 million acres) identified as Roadless Rule. States, political subdivisions and Indian Tribes would also have more authority to withdraw lands, she said. To combat the proposed changes, Skaer made 10 trips to Washington D.C. on behalf of NWMA members in 2007. In her presentation at the annual meeting, she also objected to provisions that include no life-of-mine permits and uncertain permit renewals and new and duplicative environmental standards that she said are vague, ambiguous and inconsistent with current federal and state environmental laws. Debra W. Struhsacker, an environmental permitting and government relations consultant, also spoke on the issue of HR-2262 with a presentation titled ?The House mining law bill ? Rip van Winkle is back ? and he?s meaner than ever.?

Jan 1, 2008

By T. M. Barczak

Stoppings are required to resist lateral forces on the face of the structure to control pressure differentials created by ventilating air. The design criteria in other parts of the world, including Australia, exceed this requirement by specifying over pressurization control to as much as 14 kPa (2 psi) in the active sections and 35 kPa (5 psi) in the main ventilating control areas. This is done to provide protection to the mine workers from explosive or air blast events within the mine that can create this over pressurization. The National Institute for Occupational Safety and Health (NIOSH) has been conducting research to develop a new testing protocol for rating mine ventilation stoppings. The premise of this work is that arch-loading conditions more accurately reflects the transverse load capabilities of stoppings in underground coal mines than the freestanding flexural strength test specified in the current Code of Federal Regulations (CFR). This work clearly shows that the transverse load capabilities of dry-stacked, mine ventilation stoppings are dependent upon the material strength of the block and the height and thickness of the wall, none of which are part of the current CFR criteria based on ASTM E-72 specifications. This paper compares the transverse load capabilities of several block materials and wall dimensions commonly used in stopping constructions based upon simulated three-hinge, rigid-arch loading tests of half-wall constructions in the NIOSH Mine Roof Simulator. The results indicate a wide-range of transverse load capacities, ranging from as low as 21 kPa (0.3 psi) to as much as 117 kPa (17 psi) for the conditions evaluated in this study. The current CFR criteria do not distinguish between applications of these stopping designs despite their wide variance in transverse load capabilities, which is not conducive to employing ventilation control strategies that isolate certain sections of the mine to prevent injury to mine workers.

Jan 1, 2009

By Alan Weakly

The Powder River Basin (PRB) of northeastern Wyoming and south-central Montana is the largest strippable reserve of compliant coal (0.6 or less lb of sulfur per million Btu) in the United States. In mining parlance, it is the Mother Lode! Wyoming’s portion of the Basin provides one fifth of the coal produced in the United States annually, and the state has been the nation’s top coal producer for the past six years. Based on 1993 production statistics and estimated strippable compliance coal reserves, Wyoming may remain the nation’s top producer for the next 76 plus years. Past articles on the PRB have focused mainly on production. After living and working in the Basin for the past five years, I have developed an appreciation for the area and its major industry that transcends size and production data. In the fall of 1993, MINING ENGINEERING’s publisher and I decided to present a series of articles that would cover many other aspects of the Basin. Ten topics were outlined, and specific individuals, selected for their knowledge and experience, were asked to contribute articles about their specialties. Although Montana has four large mines producing coal from the PRB, this series of articles will concentrate on the Wyoming portion of the Basin.

Jan 1, 1994

By Peter N. Calder, J. L. Workman

There are many opportunities for computers to assist in dragline mine planning. Three important areas particularly lend themselves to computer assisted study. These are overall mine design and planning, the computation and display of range diagrams and the calculation of production and production variability. The computation of range diagrams is of particular interest because of the importance of matching the dragline and site geometries. This paper examines the uses of range diagrams in dragline mining and illustrates the application of computer techniques to the computation using one such program as an example. The use of computer generated range diagrams for machine selection, pit design and in parameter analysis is discussed. Directions for further development are also provided. There is a great deal that can be done to additionally enhance the ability to provide accurate designs for the dragline operation. One area that needs special attention is the dumping of overburden around access ramps into the pit. This situation is one of the most difficult dumping sequences and affects machine selection and pit operation. It is also suggested that programs that simulate the production schedule of the drag-line would be useful. It is concluded that large overall mine planning programs are very important in dragline mining. However, smaller programs designed for a specific, task are also important tools in many cases. These are easy to learn and use, well adapted to the PC environment and provide useful information, both for design and for daily planning.

Jan 1, 1989

By H. Walqui

This paper describes operating gains resulting from standardizing operating and maintenance practices to improve the performance of the pebble crushing circuit at he Empire Concentrator. Past efforts have led to improved operating time but no additional throughput gains. New Operating standards and checklists were developed and introduced. The content and frequency of the review process indicators was then changed to take advantage of the new practices resulting in an increased feed rate and availability through the pebble crushing circuit.

Feb 27, 2013

By R. Owen, T. Canty, C. Marks

The industrial vision system provides on-line 2D particle size analysis for aggregate slurries in both the overflow and underflow of hydrocyclones. This paper covers required vision system features allowing CCD cameras to function in the harsh environment of a mine milling area. The study conducted demonstrates the system’s capacity to obtain particle size distributions for controlling hydrocyclonic separators. The particle size distribution is obtained within seconds and immediately updated to allow for process adjustments. Results are then provided as a graphical computer generated display or output as a 4-20mA current loop for process control. The primary use of the vision system is in classifying particles in cyclone overflows which are often a few microns in size. Typical size information for actual mine slurry samples are presented and possible control schemes discussed.

Jan 1, 2002

By G. Wang, L. R. Moore, Y. Xiong, A. Gorken

"Feldspar may represent 60% of the earth’s crust, but the mineral does not exist in a pure state. It is generally associated with quartz, iron containing minerals such as mica, and titanium containing minerals such as rutile. Feldspar itself can even exist in different lattices from those containing sodium to various divalent ions. As such, its beneficiation has become a process that is quite complicated, when compared to the beneficiation of other minerals. It is this complexity that has made feldspar beneficiation dependent on tailor made reagents to successfully yield the industry specified feldspar products. This paper reviews the mineralogical variations found from two feldspar mines and the development of collectors to specifically target a Fe+Ti concentration of < 0.05%, while maintaining a feldspar recovery greater than 90%.INTRODUCTION Feldspar is a class of aluminum silicates that represents the most abundant mineral on earth (Vidyadhar, 2002). This class of mineral can further be defined by the types or concentrations of cations present in the crystal lattice, MAlSi3O8 (M = K, orthoclase and microcline; M = Na, Albite; M = Ca, Anorthite) (Heyes, 2012). Feldspar is most commonly mined and processed for either the alumina used in glass making or for the alkalis used in ceramics. The alumina is known to improve product hardness, durability, and resistance to chemical corrosion. The alkalis act as flux, which means they not only lower the melting temperature of the mineral mixture, but also assist in connecting the other components present in ceramics. It was stated in 2009 that the world production of feldspar was in excess of 18.3 million tons produced, with the majority coming from China, Italy, and Turkey. Raw feldspar is typically found with quartz, iron containing minerals such as mica, titanium containing minerals such as rutile, and other feldspar minerals (Celik, 2001). Quartz is stated as having a negative effect on the melting point of the feldspar, whilst the iron and titanium based mineral contaminants are known to have negative effects on color and quality of the product produced; these mineral contaminants must therefore be separated prior to application (Barns, 1997 & Celik, 2001). Mineral flotation and magnetic separation are the most common means of feldspar beneficiation. However, conditions vary greatly from mineral contaminant to mineral contaminant (Table 1). Some literature suggests feldspar can be floated with an amine, but this generally yields lower than acceptable recoveries and often still requires the magnetic separation of iron based minerals to achieve the desired grade (Amarante, 1997 & Heyes, 2012). Feldspar flotation can be further improved with the addition of hydrofluoric acid (HF) as a silica depressant and feldspar surface modifier, but this still requires the removal of some of the other minerals first. Rutile can be floated with an anionic fatty acid collector at a pH range of 7-8 or with a petroleum sulfonate at a pH < 4 (Celik, 2001), while mica can be floated with a petroleum sulfonate or an amine collector at a pH of 3.5."

Jan 1, 2016

By Tim O’Neil

Tire companies have historically used the mining industry as a platform to launch new technologies. And the mining industry has been receptive to that. So, while developing its Two Piece Assembly, Goodyear noted a number of trends in the mining industry: •The global market sophistication of equipment and operations requires the packaging of products and services to provide the best return on investment. •Industry consolidation and growth have resulted in fewer, more powerful mining houses, leveraging purchasing power in the marketplace. •User productivity demands continue to drive original equipment manufacturers to develop higher pay-load equipment. •Technology needs include improved ergonomics, to reduce fatigue and increase operator productivity. •Increased laws and environmental regulation prohibit on-site whole tire disposal practices.

Jan 1, 2003

By Samer Sadek

The Georgia Department of Transportation (GDOT) undertook an exploratory feasibility study to one of the most ambitious tunneling projects in the United States. HNTB Corporation was retained to perform the study, deemed the Atlanta North-South Tunnel, which is approximately 7 miles long and consisting of four lanes (or six lanes) starting at the southern terminus of SR 400 extending to the south connecting with the northern terminus of I-675, providing substantial relief to the Downtown Connector (I-75/I-85), the most congested portion of Atlanta?s freeway system. This paper summarizes the analysis performed during the first phase of this challenging assignment which, if constructed, would be one of the longest roadway tunnels ever built in the United States.

By Vince Saporito

Miners work in dangerous terrain, around the clock, with heavy equipment. Is there room for improvement in safety and standardization in the mining industry? Recent history would suggest there is a need for action. At a 2011 Spring Thaw conference in Denver CO, one speaker commented, ?We are having a number of incidents with workers getting ?pulled? into rollers or ?trapped? at transfer points when trying to manually clean (it) while the conveyor is still in motion.? It?s a troubling thought. These actions are specifically prohibited under U.S. Mine Safety and Health Administration (MSHA) regulation 57.14202. Another official from MSHA earlier this year indicated with today?s technology and policies presently in place, ?we should not be repeating the same incidents and violations year after year as we currently do.? But we are doing exactly that.

Jan 1, 2012

By Robert L. Hautala

In 1978, Congress established a series of mineral institutes for a limited time to assist financially in mineral industry education and research. Later, education and research were separated, establishing generic institutes for specialized research that transferred the former research budget from the base mineral institutes program. One of the generic institutes is the Mine Systems Design and Ground Control (MSDGC). It provides for research funding specifically for mining. Other parallel generic institutes were established in pyrometallurgy, comminution, waste management, etc. MSDGC was established at Virginia Polytechnic Institute and State University(VPI). The founding group included the University of Alabama, University of Kentucky, University of Nevada Reno, University of Idaho and University of Alaska reporting through VPI to the US Bureau of Mines (USBM) and Congress. Other universities also participated on an ad hoc basis.

Jan 1, 1996

By J. B. Seymour

This paper provides an overview of the current use of backfill for ground support in underground metal mines in the United States and a summary of recent accident data reported for these mines by the Mine Safety and Health Administration (MSHA). Backfill mines comprise a major part of the underground metal mining industry and are particularly important in terms of the fatalities and injuries impacting this workforce. Ground falls are the leading cause of fatal accidents at these mines accounting for 50 percent of the total fatalities (4 out of the 8 fatalities that occurred from 2006 through second quarter of 2011). MSHA reported several different types of accidents involving backfill at these mines. While backfill ground falls do not occur frequently, these accidents result in a much higher proportion of fatalities than host rock ground falls. Backfill ground fall accidents are especially hazardous in underhand cut-and-fill mining operations where employees work directly beneath the backfill. An analysis of recent MSHA accident data supports the need for further cooperative research with the mining industry to identify and address ground control problems in underground metal mines using backfill.

Feb 27, 2013

By N. Aouad

Dump truck operators are exposed to whole-body vibration (WBV) levels that exceed the International Standard Organization (ISO) 2631-1. The WBV level measured by RMS acceleration value, for operator comfort, and long-term health and safety is under 0.315 m/s2 by these standards. However, fundamental research by Frimpong and Aouad (2009, 2012) and field experimental study by Kumar (1999) have shown that operators are exposed to extreme WBV levels exposing them to injuries and musculoskeletal diseases in the long-term. These extreme WBV values in the vertical direction are equal to 3.56 m/s2, 1.12 m/s2 and 0.87 m/s2 for the operator?s seat, lower-back and cervical regions, respectively. This paper will outline current research to solve these problems. Keywords: WBV, Truck Vibrations, MSC.ADAMS, Virtual Prototyping

Feb 27, 2013

By R. K. Dunham

It has been estimated that 30% of the United States coal reserves occur in the Western States at depths which would preclude exploitation by surface techniques. Much of this coal occurs in seams considerably thicker than those presently mined in other parts of the country. Recognizing the lack of technology and experience in exploiting the thicker seam range the Interior Department&apos;s Bureau of Mines is implementing a major "Mining System for Western Coal," research program which has as its ultimate objective the development and demonstration of underground mining methods and technology for extracting these seams. One investigation, being carried out by D&apos;Appolonia Consulting engieers, under contract to the Bureau of Mines, is concerned with design of an entry system for longwall top slicing of thick western coal seams. This presentation presents an overview of some of the problems which have to be faced in designing such layouts.

Jan 1, 1977

By Thomas A. Gray

The Dolph Mine fire site is located in Lackawanna County, PA, approximately three miles northeast of the city of Scranton. The fire was burning in both coal refuse (culm) and underground anthracite mine workings. It was reportedly begun by rubbish burning on top of a culm bank. A site investigation was completed in 2006 to define the extent of the fire and to recommend fire control measures. A cut off trench was selected as the principal control method. Plans and specifications were prepared in late 2006. The project was bid and a contractor selected in early 2007. The trench construction was completed in 2007. This paper describes the investigation and selection of the fire control method and discusses the trench construction.

Jan 1, 2009

By Alex Naudts

Pre-excavation grouting is a predictable and reliable technique performed to prevent or minimize settlement in advance of, or during the tunneling operation. It safeguards the infrastructure above the tunnel alignment. Cement based suspension grouts and sodium silicate based grouts are frequently injected to consolidate and strengthen the formation and create a reinforced canopy above the tunnel trajectory. Grouting is typically performed through permeation and permeation in conjunction with hydrofracturing. Multiple injection passes through steel sleeve pipes are ideal, since they create an effective forespiling system to facilitate tunneling without causing unacceptable settlement, even with minimal overburden thickness. Ten pre-excavation grouting projects performed in the North America are discussed in this paper.

Jan 1, 2008

By L. M. Cenegy

The formation of scale is common in gold ore processing plants. A working definition of scale, applicable to the various scaling conditions found in gold ore processing plants, would be: "a hard, tightly adhering deposit formed in place by the precipitation of calcium-bearing mineral compounds from water". The most common scale found in gold processing plants is calcium carbonate (CaCO3) although calcium sulfate (CaSO4) is occasionally a problem.

Jan 1, 1990

I am deeply honored and grateful to receive the prestigious Gaudin Award. Frankly, I find myself amazed to be included in the company of those outstanding individuals who have previously received this recognition. I am humbly honored to receive this award from an industrial research group. Gaudin was an internationally respected leader of mineral processing. His research contributions widely covered the whole spectrum of mineral processing science and technology, including comminution, size distribution, electrostatics, magnetics, thickening and, especially, the development of flotation theory and application. In his later career, he increased his emphasis on hydrometallurgical technology. In fact, one of his most notable practical contributions was in the development of leaching and ion exchange purification of uranium from low-grade ores. Gaudin catalyzed the trend in mineral processing toward engineering science for a better understanding of process mechanisms and kinetics. He said that those working in academic fields should have an underlying responsibility to the industry they represent. This imposed on him the objective of seeking out research areas that had some relevance to industry&apos;s problems. He said, "research without an audience cannot survive." Gaudin performed a most vital service, both in the areas of research in which he was actively involved and through his less-direct influence on current research by his many former students and their students in turn. Interestingly, Gaudin&apos;s strength has influenced Newmont Mining Corp. His favorite student was Plato Malozemoff. He had a long and distinguished career with Newmont, beginning as staff engineer in 1945, serving as Newmont&apos;s president for more than 30 years and as chairman of the company for 20 years. Newmont&apos;s greatest growth occurred during his leadership. Another one of Gaudin&apos;s graduate students from Montana School of Mines, Oscar F. Tangel, joined Newmont in 1967. He was a vice president of research and development until 1986. In their efforts, Newmont built a research group, developing the technologies of exploration, geophysics and metallurgy. The Newmont technical facility is named in honor of Malozamoff as "a leader in the development and implementation of new technologies." The mining industry is facing very difficult times, especially in the metals industry. Most metal prices have declined and are still not stable. Most domestic mining companies have largely done away with in-house research and development. Many are reluctant to invest in technology development for which there is not an immediate need. The metal mining industries are focusing on reducing operating costs to survive. Newmont is in the same situation. I appreciate that Newmont&apos;s management believes in the importance of research and technology and the impact technology has on the company&apos;s value. At Newmont, technology development involves working in the area of applied research. The connections from academic fundamental research to applied research and finally to process development and implementation are very important to develop a new technology. Fundamental research is our foundation, our guidance, giving us direction, providing the principal and mechanism and understanding why it works. Understanding the why will lead to further innovative development. Applied research needs to find the approach to reality, how it works, how to make it better and how to commercialize it. Process development and implementation needs a strong leadership, requires long-term commitment, makes improvements in practical engineering and finally develops an economically favorable process. Implementation is the most important stage in making research a reality. Each stage needs to give feedback to the other stages. Problems need to be understood and solved. Otherwise, the new technology will go nowhere. Simplicity of operation is a key of success in any plant. Necessity is the

Jan 1, 2002