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By J. R. Patts, L. D. Patts, S. J. Janisko, T. Barone

"Controlling float coal dust in underground coal mines before dispersal into the general airstream can reduce the risk of mine explosions while potentially achieving a more efficient and effective use of rock dust. A prototype, flooded-bed scrubber was evaluated for float coal dust control in the return of a continuous miner section. The scrubber was installed in line between the ventilation tubing and an exhausting auxiliary fan. Airborne and deposited dust mass measurements were collected over a period of three days at set distances from the fan exhaust to assess the changes in float coal dust levels in the return due to the operation of the scrubber. Mass-based measurements were collected on a per-cut basis and were normalized per foot of advance by the continuous miner. Results show that average float coal dust levels measured under baseline conditions were reduced by over 91% when operating the scrubber. INTRODUCTION In 2012, underground mining in the United States produced over 342 million tons of coal [EIA 2013]. During the cutting, crushing, and transport of this coal, dust is generated and can be entrained in the air ventilating the mine. Title 30 Code of Federal Regulations Part 75.400-1 (30 CFR§ 75.400-1) defines float coal dust as particles of coal that can pass a No. 200 sieve. These coal particles can be carried by the ventilating air into return entries before settling onto mine surfaces [NIOSH 2006]. If this float coal dust becomes re-entrained into the airstream, it can propagate an explosion throughout mine workings [Harris et al. 2010]. Application of rock dust in underground coal mines is required by Federal regulation as a means of preventing the propagation of explosions by float coal dust. In order to meet Title 30 Code of Federal Regulations Part 75.403 (30 CFR § 75.403), 80% incombustible content must be maintained in the composition of dust deposited in mine entries [76 Fed. Reg. 35968 (2011)]. This fraction of incombustible content is increased if elevated levels of methane are present. In order to maintain the required incombustible content, frequent or constant application of rock dust is undertaken by mine operators. Title 30 Code of Federal Regulations Part 75.2 (30 CFR § 75.2) defines the properties of the rock dust that must be used by mine operators."

Jan 1, 2015

By A. Gene Collins

The demand for lithium may increase because of its potential use id lithium batteries and in the generation of electrical power by fusion. Therefore, lithium abundance in some United States oil-field brines was surveyed. Oil-field brines from numerous locations were found to contain more than 100 mg/l lithium and several exceeded 500 mg/l. An area of 25,000 km2, with a reservoir thickness of 60 m, an effective porosity of 5 percent, and a brine with a specific gravity of 1.2 containing 100 mg/l of lithium, contains about 0.75 x 106 tonnes (1 tonne = 1 metric ton = 1,000 kg) of lithium in 7.5 km3 of brine. It is postulated that the brines were enriched in lithium by lithium-rich spring water or lithium leached from volcanic rocks followed by evaporation sequences.

Jan 1, 1978

By Kenneth N. Han, Xinghui Meng, A. J. Monhemius, G. W. Warren, E. Peters

The leaching of gold in ammoniacal solutions containing various oxidants in an autoclave has been investigated. Also studied are thermodynamic and kinetic aspects of the ammonia leaching of gold and silver. The variables studied included stirring speed, temperature, concentration of ammonia, ammonium, and various anions. Arrhenius activation energy values were found to be between 47.1 kJ/mol and 86.2 kJ/mol depending upon the kinds of oxidants used. An electrochemical reaction controlling mechanism has been proposed for the dissolution reaction. The leaching behavior of gold and silver from various ores in ammoniacal solutions containing various oxidants has also been investigated. The samples tested included sulfidic as well as carbonaceous refractory ores. The recoveries of gold and silver from these refractory ores were better than 96% within 2-3 hours of leaching time.

Jan 1, 1993

By Donald A. Brobst

The minerals barite (BaSO, -barium sulfate) and witherite (BaCO, -barium carbonate) are the chief commercial sources of the element barium and its compounds, whose many uses are nearly hidden among the technical complexities of modem industrial processes and products. Barite, the major ore mineral, is extremely vital to the petroleum industry, which in 1990 consumed about 90% of the world's production of 4.9 Mt as a major ingredient of the heavy fluid called mud that is circulated in rotary drilling of oil and gas wells. The remaining 10% of the barite production was consumed chiefly in the manufacture of barium chemicals and glass and as a pigment, filler, and extender. Barite is found throughout much of the world and is available from three major geologic types of deposits-vein and cavity-filling, residual, and bedded-in sufficient quantity at competitive prices to meet current demands. The world's demand for barite is expected to increase because of the world's need for oil and gas. Geologic circumstances are favorable for the discovery of new deposits of commercial value. Witherite, desirable as a raw material for the production of barium chemicals, is much less common and abundant than barite.

Jan 1, 1994

By R. V. Ramani, R. Bhaskar

Control of respirable dust in mines has been given paramount importance due to the health and safety implications associated with fine dust. Understanding the temporal and spatial behavior of dust has been recognized as essential for increasing the efficiencies of existing control techniques and for developing new control strategies. Mining-related studies in this area are, in general, limited. They are also mostly experimental. Some mathematical and computer analyses have been at-tempted. In this paper, first, a review of the mathematical studies performed in the last three decades in this area is presented. Second, a mathematical model for analyzing dust flow in mines is proposed. The model takes into account a number of factors affecting dust transport. It in¬corporates varying dust generation source strengths and dispersion, deposition, and coagulation of dust in mine airways. Finally, application areas for the model are discussed. A computer program based on the mathematical model has been developed. The program will output the dust concentration in the mine atmosphere as a function of time and distance from the source. The amount of dust deposited on the sides, roof, and floor of the airway is also determined.

Jan 1, 1987

By Eileen Ashworth

Introduction A study was completed that investigated the enrollment in mining engineering programs in 24 universities and colleges. All programs considered in the study award four-year bachelor of science degrees in mining engineering. They also provide all the engineers for the mining industry and a large portion of the geotechnical engineers working on environmental problems, storage of hazardous waste, civic, and Federal government underground projects. The numbers used as the base for the study are those reported by each program to SME-AIME and published yearly (SME, 1986). Data for the study came from the period 1975-1985. Also, since some programs include students in related disciplines and special categories, such as cooperative students, a few inaccuracies were unavoidable. A 23-page document has been prepared that reports on the overall picture of current enrollment, the trends, and discusses the results, perceived effects, and what can, or should, be done. There has been an obvious, and dramatic decrease in total undergraduate enrollment since the late 1970s. In 1978, 3117 students were enrolled. In the 1985 fall semester, enrollment was 1022, less than one-third. There were 485 seniors, 265 juniors, 147 sophomores, and 125 freshmen. The downward trend in total enrollment is likely to continue for at least another two years. Class size The catastrophic drop in enrollment is shared by all programs across the country. It does not discriminate between types of programs, coal or hard rock mining, or location. In general, 1985's enrollment is about 30% of whatever the maximum enrollment was in any program, though this varies from the teens to 50%. The latter percentage occurs only for some programs with special circumstances, particularly new programs not well established in the late 1970s. The beginning of the decline in enrollment has occurred at slightly different times as affected by the demise of each program's local industry. The numbers in each class produced from a specific freshmen year (Fig. 1) are worthy of comment. The dramatic drop in enrollment for all classes after 1982 is clearly demonstrated. The timing coincides with the general downturn in the mining industry, when many employed engineers were laid off and new graduates could not find jobs. Also, significantly fewer students are being attracted to mining programs as freshmen. The number of seniors shown seems inappropriate. Where did so many seniors come from and why are so few graduates produced? There is an increasing trend for students to take four-and-a-half or five years to graduate. Therefore, they are counted twice, once when they are first classed as seniors and again the following year. Some students purposely delay graduation to obtain more summer work experience and take additional courses. They believe that this gives them a better

Jan 8, 1986

By Steve O. Green

Introduction The US coal mining industry is in the midst of a serious economic crisis. To overcome increased operating costs, operators must take advantage of technological advancements in mining systems and equipment. A relatively new concept available to underground operators is that of extending the cutting depth for continuous mining machines (continuous miners). This system is referred to as deep-cut mining, and may be described as mining cuts to depths greater than the standard 6 m (20 ft). Productivity is increased through the reduction in continuous miner tram time since the machine stays longer in each working face. To successfully implement a deep-cut mining system, three problems must be overcome: Exposing personnel to unsupported roof, methane removal, and controlling respirable dust. Remote control cutting The solution to the unsupported roof problem is remote control. Recent advances in remote operation, especially in radio remote controls, have resulted in what is generally accepted as a safe and reliable tool. By installing remote control on the continuous miner, the operator and helper can now be stationed in a supported area. This allows for improved visibility while cutting coal. With this in mind, the limiting factor now becomes the position of the haulage equipment operator. North River No. 1 uses Joy 21SC shuttle cars and Jeffrey 4110 diesel ramcars. These cars are pulled against the bumper of the continuous miner. Thirteen meters (43 ft) can be cut with the shuttle car and 14 m (45 ft) with the Ramcar before the operator of the car is inby permanent supports. By loading away from the bumper, about 1.5 m (5 ft) can be added, bringing total cut depths up to 14.5 and 15 m (48 and 50 ft), respectively. Methane removal The second problem involves methane removal, and the line curtain-to-face distance. In other words, how to maintain the line curtain to allow sufficient ventilation to remove methane and not expose workers to unsupported roof. The solution, in most cases, is to use a blowing-type ventilation system. Unlike the exhausting system that, to be effective, must be installed within 3 m (10 ft) of the working face, the blowing system can be effective at greater distances from the face. Numerous studies have documented the advantages of a blowing-type ventilation system over an exhausting system. Furthermore, a blowing system can be significantly improved by in¬creasing the velocity of the air delivered without increasing the volume of air. With this greater ventilation efficiency, it is possible to secure ventilation plan approval from the Mine Safety and Health Administration (MSHA) for a greater curtain set-back distance. This eliminates the need for personnel to travel inby permanent supports to extend the face brattice. The distance from the face MSHA will approve, however, is on a mine-by-mine basis. MSHA will evaluate the particular mine's face methane liberation rates, along with the specific proposals regarding face ventilation volumes and velocities. Dust control The third problem is controlling respirable dust. This is actually a result of the solution to the second problem. In the blowing system, while mining on the slab cut, both the continuous miner and haulage units are located on the dusty side of the line curtain (Fig. 1). In the early 1970s, underground operators virtually abandoned this system, in order to comply with the 2 mg/m3 (0.87 gr per cu ft) federal dust standards. The blowing face curtain did offer increased face ventilation efficiency. With that, greater curtain-to-face distances were also

Jan 8, 1987

By A. Palit, M. K. Mohanty

This investigation has concentrated on optimizing the newly developed Pansep linear screen and developing empirical models to predict the screening performance. Most empirical models developed in the past to predict the performance for industrial screens are suitable for the vibratory screens. Understandably, these models are deficient in predicting the performance of linear screens due to the difference in their operating principle. Thus, the main objective of this study has been to develop empirical models suitable for linear screens to predict the partition coefficient for a given size fraction as a function of the aperture size. The inadequacy of the conventional model equation originally developed for vibratory screen has been demonstrated and a modified equation developed to predict the partition coefficient as a function of the normalized mean particle size (d/d50c). In addition, new model equations have been developed for linear screens to predict the screening efficiency as a function of the separation size(d50) and to predict the separation size as a function of the screen aperture. It is believed that these model equations will be useful for the plant operators in selecting the mesh panels of correct aperture size and in predicting the product size distribution based on the selected aperture size.

Jan 1, 2003

By E. P. Reed

We are proud that one of our predecessor companies originated the phrase "Safety First". That phrase remains today as the guiding principle that governs our total approach to safety and well being in U. S. Steel. U. S. Steel management is totally committed to this attitude and our objective is to have every employee as deeply conscious of his safety responsibilities. Safety is a state of mind but like most things it must have a physical side - both intertwined and inseparable. You might say each promotes the other; and this gives us confidence that with hard work, cooperation from all individuals, and proper application of knowledge and experience, our ultimate objective of frequency "0" will be attained. It is in this vein of thought we present a paper today which gives you briefly our progress, mainly in the physical, or mechanical, protection of miners at work in the Southern District mining operations of U. S. Steel. The Southern District not only includes the underground mining of coal but the underground mining of zinc ore in Jefferson City, Tennessee, and the quarrying of dolomitic limestone near Bessemer, Alabama.

Jan 1, 1970

By Elif Çevik

This study deals with the mineralogical-geochemical characteristics and the industrial usage of the olivine from the dunites that crop out on the west of the Topuk village (Orhaneli). Mineralogical compositions of non-altered dunite samples are averagely as: Olivine (>90%), serpentine (1-4 %), opaque minerals especially chromite, magnetite, pyrite (1-3 %), and secondary minerals as magnesite, chlorite (1-2 %). X-Ray Diffractograms of the dunite samples indicate that olivines are in forsterite (93 on an average) composition, and chlinochrysotile and lizardite accompany to the forsterite. Chemical analyses of the dunites show that MgO, SiO2, Fe-,03 and LOI contents vary from 40,99 to 50,2 %, 34,67 to 40,6 %, 6,8 tol3,7 %, 0,11 to 11,27 %, respectively. SE-TAT Mining Company states that the study area has 400.000.000 tonnes proved, 800.000.000 tonnes probable and totally 1.200.000.000 tonnes olivine reserve. Consequently, all studies indicate that Orhaneli Olivin has convenient mineralogical and chemical properties and the grain size (0.04-40 mm) for industrial usages such as abrasive, olivine sand products, steel slag conditioner, balast and covering material in industry: Orhaneli olivines are demanded especially from the firms related to refractory industry, iron-steel factories, naval forces and shipyards. SE-TAT Mining Company also exports these olivines to different countries such as Macedonian and Spain.

Jan 1, 2005

By A. Bruynesteyn

Many papers 'have been publihed on the role of the bacterium.Thiobacillus ferrooxidans in the oxidation of reduced sulfur compounds, and years of research have established the following environmental factors, which influence biological oxidation. 1. Oxygen is required for the oxidation of reduced sulfur compounds to the sulfate form. Sufficient oxygen. is available from the air, consequently, it is of importance to get the air to the bacteria. 2. The bacteria are active in the pH range 1.4 3.5. Maximum activity occurs at pH 2..0 - 2.8. 3. -In order to allow the bacterial populations to expand, certain essential nutrients must be available. Nitrogen has to be supplied for the production of body protein, and ammonia is the source most readily accepted by the bacteria. Carbon dioxide is the only utilizable source of carbon and the small amounts available in air are the primary source of this element. Small amounts of phosphate, manganese,, potassium,. calcium. and magnesium are also required. These trace minerals are available from the water and host rock in sufficient quantities. 4. Water is required as a carrier for the oxygen carbon dioxide and other nutrients, as-well as a solvent for the metallic sulfates produced. The bacteria are motile and the water allows the bacterial populations to spread:: bacterial activity ceases if the equilibrium relative humidity drops below 100%. 5.-optimum bacterial activity occurs at temperatures of 34 - 35°.C (93 -.95° F). All activity ceases above 45° C. At lower temperatures, activity its dramatically decreased, but there is still a significant amount at 10 - 11° C.- Thiobacillus ferruoxidans has been isolated from a mine with a year round temperature of 3° C. 6. Unpublished results from our laboratory show that biological leach ore oxidation takes place during the rest periods at the same rate as during the wet leaching periods providing there is a film of moisture remaining around the particles. Optimum conditions can be readily achieved in the laboratory, but application of our laboratory knowledge to commercial leaching dumps is riot as simple. Attempts to achieve improved environmental conditions for the bacteria in leaching dumps would require substantial capital investment and careful planning of leaching operations. This paper

Jan 1, 1972

By J. J. Gusek, T. C. Richmond, R. W. Reisinger

A high-altitude (9,500-ft [2,900-m]) historic underground copper mine in Wyoming discharges neutral but copper-laden water into a pristine creek. Under a Comprehensive Environmental Response, Compensation, and Liability Act (CERCLA) deferral agreement, the Wyoming Abandoned Mine Land Program performed site characterization and treatment studies in preparation for reclamation of the site. An integral part of the project included addressing the needs of a variety of interested and affected parties, including property owners, local populations, government agencies, and the media. This paper discusses an overall approach and specific methods employed to enlist public support for the project as well as some of the successes and failures experienced.

Jan 1, 2004

By J. G. Nalven

On July 1, 1999, most domestic metal mines will have to report releases of toxic chemicals into the environment for the first time as required by SARA Title 313. Some of these reportable releases will appear huge in relation to reports by other industries. The reasons for the potentially large reportable releases, special considerations for mining operations, and strategies for dealing with the reports are described. Data composited from experience with several mining companies is presented in the context of a typical gold mine.

Jan 1, 1999

By R. Henley, S. S. Webster, L. Harris

High resolution airborne magnetic and radiometric data have been shown to optimize exploration for epithermal gold deposits in the vicinity of Charters Towers, northeastern Queensland. The radiometric data allow extrapolation of poorly outcropping geology to provide a cost-effective mapping technique, even at exploration scales (eg. 1:25,000). At a regional scale (eg. 1 : 100,000) the magnetic data reflect the regional tectonics and divide the area into domains for the application of different genetic models. For example: 1. the Ravenswood Batholith is characterized by multiple intrusions dating from Ordovician to Permian age. The polarity of the magnetic anomalies implies an age for the intrusions and indicates a deposit style for exploration. 2. extensional and wrench tectonics along the northern margin of the Drummond Basin are interpreted from the magnetic data and indicate favourable blocks for detailed exploration. Genetic exploration models may be tested in favourable environments by the recognition of geophysical signatures. These signatures reflect structural, lithological and alteration patterns arising from controls on ore deposits and can be applied at regional or detailed scales.

Jan 1, 1989

By Babu R. Yama

Artificial Intelligence research has produced several tools for commercial application. Neural Networks, Fuzzy Logic and Expert Systems are some of the techniques that are widely used today. Artificial Neural Networks (ANNs) are excellent predictive, pattern recognition, and data analysis tools. In the mining industry, ANN techniques are being used commercially for real-time process control applications. Modeling of spatial data, ore reserve estimation, tunnel design, longwall stability prediction, and geologic roof classification are additional application areas in which neural networks have been applied successfully. A standard back-propagation algorithm was used to train a series of neural networks for a real-world predictive task. After training and optimizing the neural network architecture, performance of the network is measured on an independent validation set. Results indicate a correlation coefficient of up to 84 % between the actual and predicted values. A neural network model is developed for learning the spatial continuity of a mineral field and, consequently, for predicting sulfur values given coordinate values. The neural network performed not only satisfactorily, but in some cases performed better than the kriging model.

Jan 1, 1997

By W. L. Hollinshead

For more effective and cost saving production in tunnels, the machinery used on construction sites will be equipped with guidance systems combined with working procedure management systems. This paper describes sensors for these systems and various system configurations. A project is described which uses a computerized guidance system on an underground mining machine for guidance and profile control.

Jan 1, 1999

By Jean-Pierre Nossereau, Allen J. Hulshizer

The main thrust of this paper covers the design, installation techniques and experience associated with the installation of eleven 1.5 m (4'-11") and three 2.87 m (9'-5") diameter shafts in 15 to 23 meters (50 to 75 ft) of water over 1.6 Km (a mile) out in the Atlantic Ocean. The approach implemented, permits the use of pre-fabricated shaft linings and incorporates a safe dry-tap method for connecting the offshore shafts to tunnels driven blind from deep land shafts over 4.8 Km (3 miles) away. This tunnel-shaft system is a unique venture employed at the Seabrook Nuclear Power Station to meet plant cooling water requirements.

Jan 1, 1981

By Bekta? Uz

The study area is located between Orhangazi and Sapanca geographically known as Armutlu Peninsula (Figure 1). It is steep broken and mountainous with an area of 4000 km2. [ ] Economic marbles are investigated in regionally such as Orhangazi, Elmali, Menek?eyayla, Sapanca, Pamukova and they are seperated approximately 800 km2 (Figure 2). These marbles are massive, thick and dispersed as small sized outcrops in Armutlu Peninsula.

Jan 1, 2005

By Lui Bin, Li Xinghua, Jiang Guoan

By employing decision support system and Borland C++ and Foxpro 2.58 For Windows as development means and tools, this system comprehensively applies the price decision theory, fore- casting and optimization techniques as a complete theoretical system, realizing the computerization of analysis, forecasting and decision process of coal price.

Jan 1, 1996

By Yong Yuan, Wenhao Xiao, Luc Taerwe

"The static shear stiffness of an immersion joint subjected to combined compression and shear forces is investigated by experiments in a test set-up. To explore the performance of the immersion joint, the compression-shear loads, which are applied on a specimen according to test protocol, are determined based on real design situation. In this test, the main focus is on the steel shear keys and the rubber sealing. For the applied loading schemes, different levels of axial force, corresponding to the water depth of the joint, are considered as well as the changing amplitudes of the shear force. The force-displacement curve is obtained and the hysteresis is observed during the whole test. The joint‘s static shear stiffness is calculated, showing to increase linearly with respect to the magnitude of the axial force. Moreover, it is found that the rubber sealing has a significant influence on the shear behavior of the joint. INTRODUCTION An immersion joint is the connecting part between two adjacent elements of an immersed tunnel. Compared to that of the bulk elements, the stiffness of the immersion joint is relatively small. When it is subjected to shear actions, whether resulting from vertical foundation settlement or horizontal earthquake movements, shear-resistance of the joint is the main concern for a safe and reliable water-proof design. A flexible immersion joint, which normally consists of a rubber seal and shear keys installed at an element end is a common solution in practice. The way in which the shear keys and the rubber seal behave in the joint together is of vital importance to a comprehensive understanding of the shear behavior of the joint. However, in literature very few experiments on the shear behavior of immersed joints are available although the flexible joints are applied in practice for more than 50 years already. O. Kiyomiya (2004) carried out both a 3-dimensional experiment and a finite element analysis for a new type of flexible joint referred to as the Crown Seal. The results indicated that this new type of joint can be applied in practice because of the effective reduction of lateral deformation. A linear model was found in the paper of Anastasopoulos et al. (2007) to describe the behavior of the shear keys, which consider that the stiffness of the shear keys tends to infinity. R.S. van Oorsouw (2008) discussed the shear capacity of concrete shear keys in segmental joints, by analyzing the influences of reinforcement and friction force between shear keys."

Jan 1, 2016