Search Documents

By V. Duddempudi, B. Goertz, J. Brune, G. Bogin, F. S. Barreto

"INTRODUCTION In designing a new pneumatic Dust Sampling Device (DSD) for coal mines, it was essential to analyze the air and particle flow inside the device in detail using Computational Fluid Dynamics (CFD) modeling. Several CFD models were developed to simulate the air and dust flow and sample collecting process of the DSD. These CFD models were developed to assist in the design of the DSD instrument prototypes for laboratory testing. Nozzle and injection parameters such as geometry, air velocity and pressure, were varied across a wide range to obtain the optimal settings to accurately simulate the fluid dynamics of the multi-phase flow within the DSD. Accordingly, these parameters were used as a guide for the design of the DSD and to verify the dust scouring dynamics, which is designed to represent the dust entrainment during an actual methane or coal dust explosion. BACKGROUND The 2010 explosion at the Upper Big Branch mine has demonstrated the destructive violence of a coal dust explosion. A major contributing factor for this disaster was that the mine operators did not have a reliable, direct-reading method to collect mine dust and determine inert content and combustibility. This led to the development of a new prototype handheld, pneumatic mine dust sampling device (DSD), which blows a puff of air and entrains the mine dust by mimicking the entrainment process during a mine explosion. A computational Fluid Dynamics (CFD) model is used to analyze the air and dust flow inside the DSD. The objective of the CFD modeling effort is to find the optimum design of the DSD prototype, nozzle orientation, air pressure and pulse length by analyzing and varying these parameters so that the scouring action collects a valid, representative and repeatable mine dust sample. CFD MODEL DESIGN Figure 1 shows a wireframe image of the DSD which is utilized in the setup of the CFD model. The DSD has a triangular cross section and is 10 cm wide. Two nozzles with cross-sectional dimension of 2.8 cm by 0.25 cm act as inlets at the narrow end of the triangular cross section. The CFD model includes a reference plane 6 cm away from the nozzle to measure the quantity of dust collected. The geometry shown in Figure 1 was created for the model and it matches with the design of the actual device shown in the figure 2. Symmetry, along the plane X-Y through the center of the device, is used to reduce the number of computational cells in the CFD model. Figure 2 shows the prototype device used for experimental testing. CFD MODEL SETUP Figure 3 shows a hexahedral mesh with a cell size of 0.8 mm and the total number of cells is around 650,000. The ANSYS Fluent® pressure based solver with a transient case was used with a total duration of 40 ms. The 40 ms simulation time is based on experimental measurements to capture the injection of air and initial scouring of dust."

Jan 1, 2016

By Liming Yuan, Wei Tang, RICHARD THOMAS, JOHN SOLES

Lithium-ion (Li-ion) battery pack fires pose great hazards to the safety and health of miners. A detailed experimental study has been conducted at the National Institute for Occupational Safety and Health’s (NIOSH) Pittsburgh Mining Research Division (PMRD) to investigate the effectiveness of different fire suppression systems on Li-ion battery pack fire extinguishment. Tests were conducted in a well-ventilated container. Two sizes of battery packs (12 V and 24 V) were heated by heater strips to trigger thermal runaway and fire. Water mist with different flow rates, ABC powder, type D dry chemical, and water mist with F500 additives were used as the fire suppression agents. Multiple thermocouples were installed on the battery packs to measure the temperature evolution during the tests. The results indicate that the water mist with F500 additives is the most effective suppressant among the agents tested. Dry chemicals, however, do quench the fire for a moment, but cannot prevent re-ignition of the battery since they do not provide enough cooling. The findings of this paper can be used to develop safer battery fire suppression techniques in mining environments.

Jan 1, 2024

By E. W. Lindroos, Fred D. DeVaney, R. L. Bennett, R. W. Hernlund, W. R. van Slyke, W. F. McDermott, C. U. Keranen

INTRODUCTION Iron is the world's most widely used metal and constitutes about 5% of the earth's crust. Iron ores are found widely distributed throughout the world. Because of its wide occurrence and relatively low value, an iron ore to be merchantable must contain a relatively high percentage of the metal to be considered as a source of iron. Few ores containing less than 25% iron would be considered as ore unless they existed in large amounts and could be concentrated very cheaply. The grade of the ore, the ease of concentration, and the transportation cost to market are fundamental considerations deter- mining its worth. Iron never occurs as a natural metal except in meteorites. Most iron ores occur as oxides, and to a lesser degree as carbonates. A small amount is recovered as a byproduct from iron sulfides. Iron ore must be reduced (oxygen removed) to metal for use. Iron is marketed in many forms and combinations, such as pig iron and a great variety of steels. Iron is practically never pure as marketed but contains varying amounts of carbon, phosphorus, sulfur, and alloying elements such as nickel, chromium, etc., all of which affect the physical proper- ties of the end product. Please note that in this section all analyses ore on a dry basis and all tonnage figures are on a long-ton basis of 2,240 lb unless otherwise noted.

Jan 1, 1985

By J. W. Powell

Several years prior to 1962, it became obvious that in order to develop ore reserves below the Storke Level, it would be necessary to devise a method to facilitate the ore being lifted three hundred feet to the surface or six hundred feet to the mill. The final plans called for an underground crusher complex with two stages of crushing and a conveyor belt gallery for transport of the ore six hundred feet above, to the third crushing stage. Access into the area was gained in 1962, by sinking Five Shaft approximately one quarter mile southwest of the proposed complex site, and drifting into the area. Collar elevation of Five Shaft is three hundred feet above the 600 Level Crusher Complex. All muck was loaded into ten-ton granby cars, hoisted to the surface and dumped. (See Figure 1 for the relationship between Five Shaft and the Crusher Area) Drifting into the Crusher Area contunued until 1965 at which time the Crusher Room Cutout was started. The Crusher Access Drift (CAD on Figure 2) war driven and mining pm- ceeded according to the description on drawings marked Figure 3a and 3b. After the arch portion of the Cutout was excavated and concreted, removal of the center "pillar" commenced. This muck was removed with an Eimco 123C crawler-mounted front-end loader. (See Figure 4) A total of 576,000 cubic feet of rock was removed from the Crusher Cutout. All sup- port was afforded by grouted roofbolts on a specified pattern, as shown in Figure 3c. Crane support columns were put into place and held by braces welded to roofbolt heads. Sidewalls and endwalls were formed and concreted. (See Figure 5 for the finished product)

Jan 1, 1970

By S. R. Clark

"INTRODUCTION Of all the natural resources being taxed by the needs of the modern world, perhaps the most important is the continually expanding demand for water resources. As water becomes scarcer, and increasingly important, new technologies are needed to find innovative ways to preserve this precious resource. In Chile, for example, the mining industry is investing billions of dollars to build desalination plants and pipelines; bringing ocean water as far as 200 kilometers inland to meet their demand and maintain operations. It is a full-blown crisis for that nation and a top priority for their government and economy. It has been reported that world water consumption will increase by 40 percent in the next 10 years, representing nearly exponential growth. In the U.S., as more and more communities continue to be built, more drain on the current water infrastructure is created. For 25 percent of people and operations that rely on water from aquifers, this source is being consumed at a rate that will create significant problems meeting the demand in as few as two generations.1 A PROACTIVE APPROACH When it comes to controlling dust at your operation, whether a landfill, a transfer station, a haul road or another ancillary area, what are the options? We know watering is not the answer, but at the same time, we need to prevent dust from flying to ensure a safe environment and keep our skies clear of pollution, for both regulatory requirements and neighbors. Creating a Dust Mitigation Program instead of looking to buy the first dust control product off the shelf is a first step to conserve water and, at the same time, maintain the operational demands and environmental standards for a given site. The program concept is straightforward enough. However, the process of effectively constructing and executing a program is quite involved. When undertaking a program, each manager needs to work with their team and their partners/vendors in analyzing the following elements: 1. Site Expectations—It is important to understand how to balance your internal standards with your regulatory requirements, as well as how to keep your neighbors satisfied. 2. Site Aggregate—Variations in native soil, such as clay content or gravel levels, greatly affect the approach that will yield the highest results. 3. Climate—Relative humidity and seasonal variations are critical to achieving predictable results through product choice, application frequency and timing. 4. Daily Traffic—The type and frequency of traffic is an essential variable for site management. 5. Environmental Responsibilities—If you have additional, specifically defined responsibilities, the approach to your site may vary. 6. Budget—While efficiency is the goal of any program, some sites will have more stringent restrictions than others. 7. Current Usage Rates—Document and understand where you’re starting from, both with water, supporting products, and maintenance so that effective measurement of results is possible."

Jan 1, 2018

By Robert W. Roscoe

For over a century, St. Joe Minerals Corporation in Southeast Missouri has been sinking shafts for their lead mining operations. Upon discovery of the Viburnum Trend, or "New Lead Belt", St. Joe brought its experience and expertise in shaft sinking to the area. Eleven shafts were then sunk in an 18 year period, ending in 1972. In 1981, St. Joe began sinking a new shaft in the Trend with hand-picked employees from the four operating lead mines and service facilities. The paper describes the general history of St. Joe shaft sinking methods and equipment, focusing on the current development of the Viburnum No. 35 Shaft.

Jan 1, 1983

By Ellsworth R. Spencer

An assessment of U.S. western hardrock miners? noise exposures was conducted as part of a multi-year National Institute for Occupational Safety and Health (NIOSH) survey of noise exposures in each sector of the mining industry. Noise from selected mining equipment and operator noise exposures were measured, analyzed and tabulated for dissemination to the participating sites and are being used to direct NIOSH research and interventions to address the greatest noise hazards. Eighty-two noise dosimeter measurements were obtained, along with time-motion studies as the miners operated hardrock mining machines. Of the operators, 96% had daily noise doses that exceeded the U.S. Mine Safety and Health Administration?s (MSHA) permissible exposure level. The average gold miner dosages while operating the following equipment were: haul trucks - 261%, load-haul-dumps (LHDs) - 235%, single boom drills - 221%, bolters - 214% and dual boom drills - 163%. The worst exposure level was a silver miner with a daily dose of 873%. Time-motion data showed that this miner?s exposure accumulated most rapidly while operating a jackleg drill. These results will be used to help prioritize noise control development by NIOSH and other partners.

Jan 3, 2010

By R. L. Virta

Twenty-three companies mined kaolin in nine States in 2004. Production was estimated to be 7.6 Mt (8.3 million st) valued at $912 million, based on preliminary data. This was a slight decrease from 7.68 Mt (8.46 million st) valued at $939 million in 2003.Georgia was the leading producer state with an estimated 6.5 Mt (7.1 million st) in production. It was followed, in decreasing order of tonnage, by South Carolina, Alabama, California, Texas, Arkansas, Nevada, Florida and North Carolina. Georgia accounted for nearly the entire domestic water-washed, delaminated, and pigment-grade calcined kaolin production. Consumption Sales to the paper industry accounted for 49 percent of domestic sales and 64 percent of total sales. Other major markets for domestic sales were refractory products (10 percent), paint (5 percent), fiberglass (4 percent), catalysts (3 percent) and rubber (2 percent).Paper coating and filler markets accounted for about 87percent of export sales of kaolin.

Jan 1, 2005

By J. A. Herbst, A. E. Oblad, Y. C. Lo

The major cost in comminution is energy consumption, which can be as high as 50% of the operating cost. Improvements in plant operations have resulted in up to a 15% reduction in energy usage (kw-hr/t). These improvements have been made through the optimization of grinding efficiency and the use of expert model-based control systems. Optimization involves the determination of the levels of the critical-operating conditions that result in the most efficient breakage of ore in the mill. These optimal levels are identified through plant/laboratory test work and through computer simulation using advanced process models. Model-based expert control achieves the maximum performance from the grinding circuit by identifying the characteristics of the ore in the mill with an optimal on-line estimator. Using this information, the control system dynamically determines the operating point that will yield the optimal performance. Two industrial applications of grinding-circuit optimization and model-based control are presented to demonstrate the power of this new technology.

Jan 1, 1997

By B. J. Arnold

Utility coal specifications usually contain a requirement for a maximum moisture content in order to prevent coal handling problems and to minimize evaporative losses in the boiler. As most coal cleaning processes are water-based, dewatering and sometimes thermal drying steps are required to meet moisture specifications. Screens are often used for dewatering, with centrifuges and filters used to further reduce moisture in many cases. Algorithms to predict the performance of commercial dewatering devices were developed for the Coal Cleaning Simulator running under Aspen Plus? during a project sponsored by the U.S. Department of Energy and the Electric Power Research Institute. These algorithms include calculations for size degradation in the devices and fines loss to effluents, where appropriate, and a calculation for moisture content of the product based on particle size and specific gravity distribution. This paper discusses the algorithm for coarse and fine coal centrifuges and gives comparisons between predicted moisture and solids loss and published moisture and solids loss values for various particle size ranges.

Jan 1, 1996

Flawed mining studies have been major contributors to poor investment decisions in mining for many years, contributing to the long period of poor industry profitability. Most of the major mining houses have now adopted quite formal processes and quality standards for mining studies to reduce the potential for poor investment decisions in the future. Other organisations such as the World Bank also have specific requirements for particular types of studies, such as bankable studies. This increasing requirement for rigour and discipline means a highly structured and phased sequence of studies is now required along with the development and adoption of industry-wide standards in mine ventilation studies. New terms in the study process such as ?independent peer review? and ?hold and review? are assisting in this process. More traditional terms such as ?feasibility study? and ?pre-feasibility study? now have much more precise technical definitions. Specific standards for the ventilation components of the various phases of a mining study are proposed in this paper.

Jan 1, 2009

By Y. Okahara

The chlorination behaviors of pure iron and manganese oxides were investigated by combining a thermogravimetric analysis (TGA) technique with batch-boat roasting followed by leaching. Ferrous and manganeus oxides could be chlorinated readily, but, in the absence of a reductant, the higher oxides of both iron and manganese were difficult to chlorinate. Thermogravimetric analysis curves were drawn to illustrate the complexitites of the reactions, and the possible mechanisms were discussed. Then three manganiferous materials from the Cuyuna Range of Minnesota were treated by a process involving the selective chlorination of manganese followed by leaching. The results were interpreted in the light of the chlorination mechanisms observed on the pure iron and manganese oxides.

Jan 1, 1969

By Duluth Engineers' Club, Engineers' Club of Northern Minnesota

"During the last ten years great strides have been made, on the Mesabi Range, in the practice of beneficiating low grade iron ore material. By .beneficiation is meant all methods of removing impurities, and raising the iron content to a point where it can be sold in open market, the principal impurities being silica and moisture. The • general processes to which low grade iron ores are amenable are as follows:1. Thermal(a) Drying ; removes hydroscopic or atmospheric moisture. .(b) Calcining; removes carbon dioxide from iron carbonate, molecular water from hydrated hematites, and atmospheric moisture.Roasting; removes sulphur, carbon dioxide, molecular water and atmospheric moisture.Agglomeration; primarily for the purpose of preparing finely divided material for blast furnace; briquetting and sintering.2. MechanicalScreen sizing; removes rock and sand.Classification; removes sand by means of currents of water of varying velocities.Log washing; removes fine sand.Jigging; removes larger particles of impurities than is possible by log washing. Certain types of jigs remove fine sand.Reciprocating tables; recover fine iron particles from sand discarded by above processes.Magnetic separation; applicable to the commercial separation of the magnetic oxide of iron from gangue material. From a scientific standpoint it is possible to separate certain hematites and limonites from their gangue:(g) Miscellaneous processes; comprise dry concentration, electro-static separation and other processes."

Jan 1, 1920

By John F. Gamble

Paper 1?South African experience with asbestos-related environmental mesothelioma: Is fiber type important? Neil White, Gill Nelson, Jill Murray The purpose of this review was to illustrate the importance of the type of asbestos in environmental mesothelioma. South Africa is a logical place to assess fiber type. The three major types of asbestos (crocidolite, amosite and chrysotile) were mined (all asbestos mining stopped in 2002) in South Africa. The association between asbestos and mesothelioma was discovered in South Africa. The occupational literature indicates high mesotheliomagenic potential for crocidolite, less for amosite and less still for chrysotile. Since South Africa has been a major source of crocidolite, relatively high rates of mesothelioma in the mining population is not surprising. High rates of mesothelioma due to environmental exposure is surprising, except perhaps when the authors? point out potential sources for community exposures (e.g., mine tailings used for road surfacing, golf courses, brick and plaster making; insulation in residential ceilings; children playing on fiber-rich waste rock). The authors? reviewed four studies reporting on mesothelioma cases and their sources of exposure and fiber type. Overall 23% of the known cases were attributed to the environmental (not occupational) exposure and about 90% were due to crocidolite asbestos. The proportion of environmental mesothelioma is considerably higher than in Western Australia where crocidolite is also mined. There the overall rate of environmental mesothelioma is about 6% (and less than 1% from residence in a crocidolite mining area).

Jan 1, 2007

By James W. Babcock

Introduction Geologic ore deposit models are key to any exploration program. In the search for ore deposits, the geologist first tries to understand the genesis of known ore bodies. During reconnaissance and evaluation of a prospect, a valid exploration model of a known ore body can help the explorationist focus on critical geologic attributes of the target area. Exploration models can conserve exploration funds that might otherwise be spent collecting data not critical to delineating an ore body. This article examines the benefits of using models, factors to be considered in developing models, and examples of the way recent models have evolved. New exploration concepts and techniques are developed in response to increased competition in the mining industry. New techniques can give an exploration group a slight edge that may translate into a discovery. Mine geology staffs may find previously unlooked for extensions to the ore body by applying new genetic concepts. When all appropriate techniques are applied to exploration and mining efforts, greater efficiency and increased profits may result. Before the 1950s, scientists speculated on the genesis of ore deposits and other natural phenomena. But they presented their results as if universal and final, even though they applied to only a few deposits. Because it did not provide sufficient criteria to distinguish the genetic processes, the classic conflict between hydrothermalists, epitomized by Lindgren, and nonhydrothermalists did not help the minerals explorationist much. Important information about individual ore deposits, such as age of the host rocks and mineralization, composition of the mineralizing fluids, and separation of mineralizing and nonmineralizing events in the paragenetic sequence, could not be gathered with past equipment and methods. But these early concepts of ore genesis contained excellent empirical observations, perhaps the most useful parts of these hypotheses. Through the years, prospectors have found most of the ore deposits in the world using direct observations and their collective empirical wisdom - an empirical model. The geologist's contribution becomes increasingly important after the more obvious surficial ore deposits have been discovered. In Europe and North America that time has arrived. With the introduction of sophisticated equipment and matching techniques in the 1950s in geochronology, geochemistry, geophysics, remote sensing, and computers, many previously equivocal genetic questions can be resolved. This proliferation of highly technical data has allowed the construction of many well-founded genetic models.

Jan 12, 1984

By Michael Lenz

Predictive maintenance technologies including vibration analysis, tribology, infrared thermography, ultrasonic detection, and electrical measurements have been applied to large electric mining shovels. The predictive program was initiated on the P&H Model 2300 and 4100 electric shovels. The utilization of these technologies has shown the potential for improving electric mining shovel availability and minimizing maintenance costs. Predictive technologies provide the tools to assess machinery condition. Availability is enhanced by the condition based planning of component replacement. Maintenance costs are minimized by focusing resources through condition based prioritization.

Jan 1, 1997

By R. G. L. McCready, G. Dr. Heinrich, V. I. Lakshmanan

The objective of this study was to prove repeat loading capacities of physically stabilized fungal biomass from Penicillium sp. for the removal and recovery of uranium from mine water (Denison Mines). The testwork was carried out on a bench scale in small columns and proved that it is possible to stabilize the biomass in an inorganic compound. A lifetime of 10 loading-eluting cycles of the stabilizer biomass product was obtained by additional pretreatment. Sodium carbonate proved to be an effective elution medium. Loading and elution can be controlled by the pH values of the column. The effective loading capacity until the breakthrough point is approximately 70 % of the overall loading capacity. The loading capacities of the stabilizer biomass product are comparable to that of the original biomass. Uranium recoveries of 90 to 99 % were achieved during the loading and eluting under optimized conditions. Depending on the used biomass the described process might be applicable to remove uranium or other dissolved heavy or rare metals from effluents.

Jan 1, 1989

By C. E. Jordan, B. J. Scheiner

The Bureau of Mines conducted research on the flotation hydrodynamics of fine particle flotation to improve the flotation efficiency in our domestic minerals industry. The turbulent fluid velocity profile was measured in various flotation cells at different levels of dissipation energy. The importance of dissipation energy and bubble size within the flotation cells for the flotation response of a chalcopyrite ore was evaluated. Both increased turbulent fluid flow and fine size bubbles improved the flotation rate of fine size chalcopyrite particles.

Jan 1, 1989

By Kenneth M. Reim

In 1971, United States Borax & Chemical Corporation (U.S.Borax) initiated a mineral exploration program on federal lands in Southeast Alaska, with the commitment that any possible development would be done with great care for the environment. This program resulted in the discovery of a molybdenum deposit and the location of mining claims in 1974, in an area 45 miles east of Ketchikan, now called the Quartz Hill Molybdenum Project (Figure 1). At the time of this mineral discovery, the area was part of the Tongass National Forest, managed by the Forest Service, United States Department of Agriculture, and open to mineral entry and multiple use. In late 1978, the area was designated Misty Fjords National Monument and closed to mineral entry, and in late 1980 the area surrounding Quartz Hill was classified as Wilderness. These new laws and regulations, as well as the special interest environmental groups which oppose resource development, have significantly delayed and increased the costs of developing Quartz Hill.

Jan 1, 1983

By R. J. Sweigard, R. V. Ramani

G.F. Learning The paper by R.V. Ramani and R.J. Sweigard is a wonderful description of the labyrinthine web that has been spun about the mining industry by energetic bureaucrats and politicians over the past 50 years. The remedy for the problem, however, is not more of the same, but less. That may be difficult for the industry to achieve, for it is not a technical solution but a political one. And the current fervor for more detailed planning at all levels of government and private enterprise has become deeply ingrained. The authors recommend the provision of more information about mining and mineral resources to "macro" (i.e., government) land use planners. They apparently overlook, however, the already strong tendency on the part of most government land use planners to consider themselves omniscient. Thus, giving them more information about the technical problems of mining will only make them want to get more and more involved in the "micro" (private, site specific) mine development and production plans of the individual mining firm. In fact, this has already happened at all levels of jurisdiction from municipal to federal government. Examples are legion. The most effective way to ameliorate the adverse impacts of government land use planning on existing and potential mining operations is to: (1) introduce greater flexibility in the definition of land use zones by local and state governments; (2) adopt realistic and relevant ambient environmental performance standards in governing relationships between mineral land uses and concurrent or subsequent nonmining land uses; (3) allow greater leeway for economic considerations in land use decisions in contrast to the explicit legalistic approach now in vogue; (4) recognize that all minerals are not the same and that sand and gravel mining should not be treated the same as underground metal mining, coal stripping, oil field production, or in situ leaching; and (5) eliminate the notion that mining operators should be responsible for determining in detail the use of land by subsequent owners of mined land. This last bit of conventional ethic really makes no more sense than requiring the builders of every shopping center or government office complex to provide detailed plans for the use of that land when its use for shopping or government is ended. Did the builder of Ebbetts Field plan for Brooklyn after the Dodgers went to Los Angeles? Should the developer of the Bingham Pit plan for suburban Salt Lake City after the copper mining goes to Chile? The nation's mining industry must address these questions before further bankrupting itself to provide more data to planners and spending thousands of dollars per acre to create land that when reclaimed is worth only a few hundred dollars per acre. Reply by R.V. Ramani and R.J. Sweigard We thank Mr. Leaming for his valuable contribution. His views on the problems of land use planning and mineral resources are most welcome additions to our paper. As the title indicates, our paper was more concerned with the impacts of land use planning on mineral resource conservation than with the details of the planning process. On the whole, his five recommendations would be helpful for mineral resource conservation. However, we would suggest that the argument he presents for his final recommendation does not address the differences between mining as a land use and commercial or institutional uses. We believe that this difference is the crux of the issue. We share Mr. Leaming's desire to ameliorate the adverse impacts of land use planning. Possibly the most detrimental impact is the loss of mineral resources. Any development, whether mineral or community, that does not give proper consideration to other resources can result in permanent loss or sterilization of resources. With proper planning, some of these losses can be avoided. As our paper indicated, one factor that limits the consideration of mineral resources, and ultimately leads to their sterilization, is the generally inadequate levels of resource characterization and understanding of the unique nature of mineral resources and mining operations. The last point raised by Mr. Leaming is also important. In terms of reclamation and land use planning in mining districts, we certainly do not advocate spending more than what the results are worth. The main thrust of the paper was to explore the avenues for conserving the mineral resources so that, at some appropriate time, the issue of mining and reclamation can still be addressed.

Jan 4, 1985