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The surface properties of eight coal samples were studied by measuring contact angles, coal oxidation, equilibrium moisture and film flotation. The penetration tests were carried out with do de cane, while dodecane and MIBC were utilized in batch flotation tests and in the simplified release analysis. Coal floatability results from the properties of coal organic matter and coal liberation. While the wetting of coal by water seems to be determined by the surface properties of coal organic matter, wetting by hydrocarbons correlates very well with the content of coal mineral matter.

Jan 1, 1992

By Dai Wang

Stoppings are necessary ventilation control devices for effective air distribution underground. However, one of the major problems underground mining has is that every stopping is a potential leaking source. Since air always flows from a point of high pressure to one of lower pressure, and the total pressure at every point in intake airways is higher than that in the return airways, air will always tend to leak from intake to return (Tien, 1996). In many mines, less than half of the air entering the mine actually gets to the working areas; the rest of it simply short-circuits directly to return airways through leaky stoppings instead (Timko and Thimons, 1983). Leakage through a stopping occurs because of pressure drops across the stopping and available leaky path in stoppings. Empirical equation has been widely used to characterize the relation the amount of leakage and variables that affect leakage. However the use of this equation requires accurate information for constants which are not always readily available. It is the attempt of this paper to derive an equation similar to the Atkinson Equation that can readily be applied to characterize pressure-leakage relationship for any given stopping.

Jan 1, 1998

By H. Mischo, R. Ellmies

Uranium has been mined in Namibia since the 1970s. The worldwide increasing need for energy in the early 2000s has led to the development and opening of a second uranium mine in 2007 and has triggered an increased interest in uranium exploration, often referred to as “the Namibian Uranium Rush.” In all, four mining licenses have been granted by the Namibian Government, which currently has two mines in operation, a third undertaking trial mining and the fourth in project finance negotiations. In addition, highly intensive prospecting activities at additional deposits are at an advanced stage. The finalization of the strategic environmental impact assessment (SEA) on uranium mining in 2010, the first of its kind and scale in the world, has enabled the Namibian government to assess this uranium rush and its tremendous legal, socioeconomic and environmental impacts and to prepare for the different future scenarios conceivable when this article was written in 2011, including both a skyrocketing and a complete breakdown of demand scenario. The Fukushima disaster and plans of the Namibian government to significantly increase royalties and company taxes in 2011 have threatened the market situation, forcing investors to reevaluate Namibian uranium mining projects. However, with the tax and royalty increase initiative since withdrawn, most projects are back on track at this point in time.

Jan 1, 2012

By T. Mills, M. Evatz

Newmont’s Lone Tree Mine, located in northern Nevada, is an open pit gold operation supported by a standard truck and shovel mine production fleet (Caterpillar 785Bs and Hitachi EXs). Newmont continues to search for ways to decrease capital expenditure and lower operating cost, hence the implementation of the Ultra Light Body (ULW) concept. The fundamental idea associated with the ULWs is the increased payload potential. Economic justification comes from successful achievement of additional payload, within the truck’s rated GVW, without changing its loading and hauling characteristics. The increase in payload capacity allows equivalent tonnage movement using fewer trucks.

Jan 1, 2001

By J. C. Stankus

To protect mine personnel and moving equipment at underground roof fall areas, mine operators typically install steel sets, which are covered with wooden blocks and backfilled with an expanding type cement material. In large roof falls, the cost of void backfilling becomes prohibitively high causing some mines to leave the voids open. However, the durability of wood over time and the capability of the steel set and wood lagging to resist falling rock are unknown. This has caused concerns for the Mine Safety and Health Administration (MSHA) and ground control engineers. During past two years, Keystone Mining Services, LLC designed and developed various impact-resistant steel set designs that were approved by MSHA and installed in various underground fall rehabilitations. This paper presents the patent pending impact-resistant steel set design methodology, including (1) steel set design per AISC national standard, (2) design, development, and laboratory testing of a water proof composite impact resistant lagging panel, and (3) impact resistant steel set design based on Law of Conservation of Energy. Two underground cases will be included detailing the application of the system.

Jan 1, 2011

By A. L. de Vegt

For the past ten years Paques has been engaged in the development and installation of treatment systems based on biotechnological processes to remove sulfur compounds from water, air and gaseous streams. Metal and sulfate can be removed from mine waters using two biological steps: 1. Sulfate reducing bacteria convert sulfate to hydrogen sulfide (H2S). The H2S reacts with the dissolved metals to form insoluble metal sulfide precipitates. 2. Sulfide oxidizing bacteria convert excess H2S to elemental sulfur. Paques has designed and installed a groundwater treatment system for the Budelco zinc refinery in the Netherlands to remove metals and sulfate as described above. The system has been operating since May 1992 treating a flow of 5000 m /d. A pilot plant started operation in November 1995 at Kennecott's Bingham Canyon Utah copper mine to develop the processes for metal and sulfate removal from groundwater and selective copper recovery from leach water. The principle of the biotechnological methods, full scale experience, and an overview of the test program at the copper mine are presented.

Jan 1, 1997

Column flotation cells continue to gain acceptance in the coal industry for the treatment of high-ash streams containing clay slimes. Unfortunately, some industrial installations have failed to meet expectations due to improper scale-up, incorrect operation and poor ancillary circuit design. To overcome these problems, case studies have been conducted to fully define the capabilities of column cells for coal applications. These data have been used to develop generic engineering guidelines for column circuit design and operation. An economic analysis has also been conducted to illustrate the importance of key capital cost considerations. These analyses indicate that column cells are significantly more expensive than conventional machines, although this difference can be greatly reduced through the installation of very large-diameter columns.

Jan 1, 1999

By MARK J. VANARELLI

Estimating groundwater inflows in rock deep tunnels is critical to the safety of personnel constructing the tunnel and the cost of construction. This paper presents two case studies for estimating steady-state groundwater inflows into deep rock tunnels. The case studies included the Chattahoochee and Nancy Creek tunnels. In this paper, statistical methods were applied to packer test data obtained from exploratory borings during geotechnical site investigations. A semi-empirical procedure was utilized for estimating groundwater inflows into these deep rock tunnels. The Chattahoochee and Nancy Creek tunnels are deep rock tunnels which exhibit radial flow conditions. For the radial flow condition, a statistical analysis presented in this paper indicates that the semi-empirical procedure works well; however, variations in the procedure and/or an insufficient amount of testing could lead to underestimations of the inflow quantities. Packer test data plotted in histograms were observed in all cases to be log-normally distributed for the radial flow condition. Modeling using Monte Carlo simulations was observed to be an effective tool for removing irregularities in the distribution of the data and incorporating high-end permeability data to derive reasonable groundwater inflow estimates.

Jun 13, 2021

By T. V. Falkie

REMARKS OF DR. THOMAS V. FALKIE, DIRECTOR, BUREAU OF MINES, U.S. DEPARTMENT OF THE INTERIOR, BEFORE THE FALL MEETING OF THE SOCIETY OF MINING ENGINEERS, AIME, ACAPULCO, MEXICO, SEPTEMBER 23, 1974 This is a time of uncertainty on the world mineral scene. For some of the world's so-called "developed" countries, reserves and production of key minerals are running low. And, we have learned that the energy so essential in recovering and processing minerals can suddenly be in short supply. The prospects for a "no growth" situation in energy or mineral consumption are practically nil. Moreover, the world's economy is in flux, casting doubt on whether traditional mineral customers will continue to be able to buy, or for that matter, whether traditional suppliers of minerals will continue to sell. It is clear that the mineral situation is contributing to world inflationary pressures, which incidentally are most damaging to developing countries. So it is appropriate that SME members devote this session to the world mineral situation, and consider some of the opportunities and responsibilities that we will inevitably encounter as the future becomes the present. The opportunities, to me at least, are especially intriguing, I have the good fortune to be part of an organization that has an enormous capability and responsibility for dealing with mineral problems. The Interior Department's Bureaus, including the Bureau of Mines, have been around for a long time. They are. a prolific and reliable source of both mineral information and mineral technology.

Jan 1, 1974

By P. R. Taylor

Recent research by the investigators has evaluated the oxidation roasting of refractory gold concentrates in the presence of hydrated lime. (Taylor, 1990, 1991, 1992, 1993). These results have indicated that it may be possible to roast concentrates in such a way as to contain nearly all of the sulfur and arsenic in the roaster calcine and that cyanidation may be possible. To further evaluate the behavior of this type of roasting system a laboratory cyclone reactor was built and operated using pyrite and hydrated lime as a .model system. Approximately 50 years ago, the principle of cyclone firing entered practical boiler construction. The appeal of the cyclone configuration was that it afforded the flash combustion process greater efficiency due to turbulence-induced increased mass transfer, heat exchange, and combustion rates.

Jan 1, 1994

By C. W. Baxter

Eveleth taconite company was formed in 1963 to mine and beneficiate taconite on the Mesabi range of Minnesota. Its thunderbird mine is located midway between the cities of Eveleth and Virginia, Minnesota, and the crude ore is transported by rail to its Fairlane plant approximately ten miles to the south of the mine, "figure 1". As is implied by the names of the mine and plant, the ford motor company is the principal owner of Eveleth taconite company, with an 85% interest, Oglebay Norton company holds the remaining 15% interest and also is the managing agent.

Jan 1, 1972

By Nick Hasenack

In the pelletizing plant of Hoogovens, Estel BV, a varying mixture of hematites and magnetites is used for the production of acid and (occasionally) fluxed pellets. Optimum results regarding productivity, quality and process control are obtained with mixtures containing 30-40 % magnetites. A decrease of the magnetite ratio or an increase of the basicity has a great influence on both productivity and heat and power consumption. Tests have been carried out to find the extent to which magnetite can be replaced by b.f. dust, mill-scale and coke breeze. Pilot plant tests show that about 80-100 % of the production loss due to a decrease in magnetite content or to the increase in basicity can be regained without damage to the quality by adding coke breeze. The amount of coke breeze should be limited tot 1,5 %; if this percen¬tage is chosen higher, the quality of the pellets deteriorates rapidly. The amount of coke breeze to be added should be about 30 % above the theoretical value, based on heat balance considerations. The results achieved by incorporating b.f. dust and mill-scale into the pelletmix were also encouraging, but as some types of mill-scale are very difficult to grind and the supply of b.f. dust is limited, the research has not been carried out extensively in this field. The pilot plant tests on replacement of magnetite by coke breeze have been followed by industrial tests, during which the breeze was added to the ore feed before the dry-grinding system.

Jan 1, 1977

By T. L. Carstensen

The Miami In-situ mine of BHP Copper is located in Globe-Miami, Arizona. The mine leaches mineralized leach capping over a supergene enriched sulfide deposit, and has produced over 500 million lbs of copper during the last 50 years. The Miami unit has identified several opportunities to enhance and expand in-situ production. A computer block model consisting of strict geologic controls, mineralogy, and metallurgical data was developed to assist in the determination of the leachable copper resource. An understanding of the accessibility and solubility of the resource to leaching solutions and the integration of hydrogeologic and hydrometallurgical information was necessary for completion of this project.

Jan 1, 1997

By John S. Wakeman

The progress results of a pilot plant study on the effects of ball top size and other mill operating parameters are reported. Test series on taconite and quartzite crude ores using a 1.7m diameter primary mill in closed circuit with a vibrating screen indicate clear trends on the improvements of mill throughput and power consumption when using larger diameter balls. Possible effects on mill liner and ball consumption as well as future research plans are discussed.

Jan 1, 1984

By S. Shankar

The phenomenon of re-entrainment is seen in many environments, such as sand dune formation, soil erosion, fugitive dust emission, spread of radio-nuclides from accidents involving nuclear weapons, etc. A thorough review of existing literature reveals that work on re-entrainment of dust in mine atmospheres is scant. The present study was undertaken as a part of on-going research in the Respirable Dust Center on the prediction of ambient dust concentrations in mine atmospheres (Ramani, 1983) to identify the contribution of dust re-entrainment to the spatial and temporal concentration in mine airways and included wind tunnel and in-mine studies. A set of seven experiments was performed in the Lake Lynn Laboratory Mine of the U.S. Bureau of Mines under controlled conditions. Two types of source coal dust, anthracite and bituminous, were subjected to airflow with a range of air velocities and walking by two different walkers. Six sets of instruments were used along the test section for sampling the airborne particles. The average air velocity just above the coal dust bed varied between 2.1 to 3.2 m/s. Due to re-entrainment as a result of the airflow conditions, the average respirable dust concentration in the center of the mine airway increased to 0.09 mg/m3 (standard deviation = 0.03 mg/m3) from an initial value of 0.02 mg/m3. The concentration of all (i.e., total) airborne dust increased to 0.17 mg/m' (standard deviation = 0.10 mg/m') from an initial value of 0.02 mg/m'. The action of personnel walking, however, caused higher amounts of re-entrainment. Average concentration of respirable and total dust at the center of the mine airway increased to values of 0.28 mg/m' (standard deviation = 0.12 mg/m3) and 1.53 mg/m3 (standard deviation = 1.0 mg/m3), from initial values of 0.03 mg/m3 and 0.05 mg/m3, respectively. It was observed that the dust concentrations were much higher near the floor, immediately at the end of the coal dust bed. Depending on the level of activity and the amount of dust deposited in mine airways, re-entrainment may become an important source of airborne dust away from the point of actual mining.

Jan 1, 1994

By A. Cecala, J. Noll, J. Organiscak

Many underground metal/nonmetal mines are using enclosed cabs on mining equipment to reduce the exposure of miners to diesel particulate matter (DPM). However, some enclosed cab systems may not be meeting their expected efficiency in capturing DPM, which could be a result of inappropriate filter use, cab leaks or insufficient pressurization. NIOSH investigated several types of filters for reducing DPM to determine which type had the best capture efficiency. The laboratory results indicated that a MERV 8 (minimum efficiency reporting value, as defined by the American Society of Heating, Refrigerating and Air- Conditioning Engineers) filter captured about 50% of the DPM, a MERV 16 filter collected 96-98% of the DPM and two HEPA (high efficiency particulate air) grade filters captured over 99% of the DPM. NIOSH also performed a field study to measure the efficiency of two cabs at a limestone mine. The cab filtration systems of a loader and haul truck were found to be over 90% effective in removing DPM, except under certain operating conditions when the efficiency was as low as 41%. A possible reason for the low efficiencies is an open window in the cab, but more studies need performed to obtain a better understanding of the cause and solution of the problem.

Jan 1, 2011

By A. Rai

"This paper provides an overview of the current use of auxiliary ventilation product and the challenges with limited air quantity in dead-end entry or working face. The PVC low frictional factor, low physical constraint and minimum leakage ventilation duct was development with ""made in US and used in US"". The PVC duct development covering operational and total cost of ownership with on-going success will be presented. This paper will discuss mine sites using new PVC vent duct underground and the results from operational and technical side making a difference. INTRODUCTION The Turquoise Ridge Joint Venture (TRJV) is located in northern central Nevada, and is situated within the Basin and Range province, near the northeast end of the Osgood Mountains (see Figure 1). The TRJV mine consists of typical Carlin type- gold mineralization characterized by low strength rock of altered limestone’s, siltstones, and mudstones. The weak nature of the ground facilitates the underhand cut and fill mining methods [3].Mining Method; Underhand cut and fill : The mine uses underhand cut and fill method which has 12’x12’ top cuts and several different size undercuts. The ore body is accessed off of a secondary development heading, utilizing a heading with a cross section of 14W x 14H or 15W x 16H configuration. In the wider and more massive zones, two headings in a production panel may be worked at any one time. Drift round lengths are determined by the type of drilling machine being used. An example of a typical topcut and associated undercut layout is shown in Figure 2. SECONDARY / AUXILIARY VENTILATION IN UNUNDERGROUND METAL MINES The auxiliary ventilation system provides the required air volumes at the face of dead-end developments and production workings, which in many cases may be considered as the primary method of assuring that the air quantity and quality standards in these working areas are satisfied. The Auxiliary fans and ducting systems are usually the primary means of delivering the required air volumes to the face of dead-end developments and production workings. Both centrifugal and axial-flow fans are used in underground auxiliary ventilation systems, usually electric powered. The internally direct driven axial-flow fans tend to be more popular because of their compactness and adaptability to staging. The most commonly used materials for ridged tubing are coated steel, alloyed steel, fiberglass and resin. Flexible (collapsible) ventilation tubing is also used and is usually made from neoprene-coated or nylon material. To add stiffness and reduce collapsibility these fabric ducts can be formed over a steel spring frame. A very important factor in the design of an auxiliary ventilation system is to minimize leakage and reduce the frictional pressure losses along the auxiliary ducting systems by minimizing their friction factors (K)."

Jan 1, 2015

By MARK J. VANARELLI

Estimating groundwater inflows in rock deep tunnels is critical to the safety of personnel constructing the tunnel and the cost of construction. This paper presents two case studies for estimating steady-state groundwater inflows into deep rock tunnels. The case studies included the Chattahoochee and Nancy Creek tunnels. In this paper, statistical methods were applied to packer test data obtained from exploratory borings during geotechnical site investigations. A semi-empirical procedure was utilized for estimating groundwater inflows into these deep rock tunnels. It is the most widely used method/procedure in the tunnel industry. The Chattahoochee and Nancy Creek tunnels are deep rock tunnels which exhibit radial flow conditions. For the radial flow condition, a statistical analysis presented in this paper indicates that the semi-empirical procedure works well; however, variations in the procedure and/or an insufficient amount of testing could lead to underestimations of the inflow quantities. Packer test data plotted in histograms were observed in all cases to be log-normally distributed for the radial flow condition. Modeling using Monte Carlo simulations was observed to be an effective tool for removing irregularities in the distribution of the data and incorporating high-end permeability data to derive reasonable groundwater inflow estimates. This paper is based on the PhD thesis entitled “Improvements to the Current State of the Practice in Steady-State, Groundwater Inflow Estimates into Rock Tunnels based on the Application of Statistical Analysis Methods of Packer Test Data obtained from Exploratory Borings During Geotechnical Site Investigations.”

Oct 9, 2020

By J. A. Organiscak

Enclosed cab filtration systems are typically used on mobile mining equipment to reduce miners? exposure to airborne dusts and diesel particulates generated during mining operations. Various filter configurations can be used within the heating, ventilation, and air conditioning (HVAC) systems of cabs to remove the airborne contaminants. The air cleaning performance of cab filtration systems is highly dependent on the efficiency of the air filters, the number of filters used, and their placement within the HVAC system. This paper shows how to mathematically model cab filtration systems and illustrates a methodology for developing other cab filtration system design models. Node diagrams of several filtration system circuits are illustrated with their mathematical models at steady state airflow and concentration conditions. Laboratory and field data are presented to demonstrate the validity and utility of modeling enclosed cab air cleaning performance. The paper concludes that incorporating multiple filters throughout the HVAC system improves the air cleaning performance and robustness of the cab filtration system design.

Feb 23, 2014

By Christopher E. Dianora, Matthew Sorrell, Eileen Test

"Constructed between 1939 and 1945, the Rondout-West Branch Tunnel (RWBT) portion of the Delaware Aqueduct is 45 miles (72 km) long. The New York City Department of Environmental Protection (NYCDEP) first identified suspected areas of leakage from the RWBT in the 1990s. A $1 billion project is underway to mitigate the leakage through the construction of a bypass tunnel around the area of most severe deterioration, a 2.5-mile (4 km) section located beneath the Hudson River. Two shafts, 800 and 900 feet (244 and 274 m) below the ground surface, are being sunk to support the tunnel construction. The deep shafts will be subjected to high groundwater pressures and have been designed to accommodate multiple tunnel portals. This paper discusses the engineering decisions and analyses leading up to the final design. INTRODUCTION Project Background The New York City Department of Environmental Protection (NYCDEP) provides over 1 billion gallons (3.7 billion liters) of water to over 9 million residents of the City of New York and surrounding communities each day. This water is stored in upstate reservoirs and conveyed to the City via a system of aqueducts and tunnels. Water is delivered to the City almost completely by gravity and consists of three systems: the Croton, the Catskill, and the Delaware. The Delaware System is the largest of the three and supplies between 50% and 70% of the City’s daily water supply. In the 1990s, the NYCDEP discovered leaks in the central 45-mile-long (72 km) portion of the Delaware Aqueduct known as the Rondout-West Branch Tunnel (RWBT). The leaks release between 15 and 35 million gallons per day (MGD) (132.5 million liters per day) and are concentrated in two areas near Wawarsing and Roseton, New York. As part of the Rondout-West Branch Bypass Tunnel and Wawarsing Repairs Project (Bypass Tunnel Project), the leaks in the Wawarsing area will be repaired by grouting from inside the existing RWBT, and the leaks in the Roseton area will be mitigated by constructing a bypass tunnel parallel to and 1,750 feet (533 m) north of the leaking portion of the existing RWBT. Two deep shafts will be excavated on either side of the Hudson River: Shaft 5B in Newburgh and Shaft 6B in the Town of Wappinger."

Jan 1, 2016