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Lower costs associated with hands-on training in donning and using a CSE ,self-contained self-rescuer (SCSR). Background In June 1987, the Mine Safety and Heath Administration (MSHA) issued an Emergency Temporary Standard (ETS) requiring that all persons entering underground coal mines must be given bands-on SCSR training. The ETS will shortly be replaced by a new standard requiring this hands-on training. Bureau of Mines research has shown that the most effective means of delivering this training is to have the trainee go through a six-step training procedure while in a kneeling position. Once the miner has looped the neckstrap over his or her head, he or she completes the donning sequence in this order: 1) activate oxygen; 2) insert mouthpiece; 3) put on nose clips; 4) put on goggles; 5) adjust neck and waist straps; and 6) replace miner's cap and prepare to move out. This procedure is repeated until the miner demonstrates that he or she is proficient at the task.

Jan 1, 1988

By J. R. Welty

High-temperature thermodynamic data have, in recent years, become increasingly important for the extractive metallurgist. The extraction of metals from their ores previously was based on trial and error methods, involving hours of testing and often costly equipment fabrication. Using thermodynamic data it is frequently possible to predict the feasibility of a proposed metallurgical process as well as the optimum operating conditions for the process with reasonable accuracy. Such predictions can save consider-able tim~ and expense. Widespread use of thermodynamic analyses has been handicapped by lack of dependable experimental data. Investigators, notably K. K. Kelley (4)4. have devoted many years to determining and compiling such data. These investigators, although prolific in their production of thermodynamic values, have been unable to meet all the needs of industry and other branches of science. This becomes obvious when one considers the aeronautical and nuclear fields, in which previously unimportant, therefore uninvestigated, substances have become of prime importance.

Jan 1, 1962

By E. D. Regad, W. E. Wallace, V. Vallythan, V. Castranova, P. Hathaway, F. H. Y. Green, M. J. Keane

"Abstract—Inhaled particle contact with pulmonary surfactant in the hypophase lining pulmonary alveoli was modelled in vitro by exposing two respirable sized dusts, kaolin and silica quartz, to lecithin, a major component of pulmonary surfactant, emulsified in physiological saline. Lecithin adsorbs to the dusts upon incubation at 3TC and suppresses their cytotoxicity as measured by pulmonary macrophage and erythrocyte assays, suggesting that pulmonary surfactant provides a defence system against prompt cell membrane lysis by inhaled dusts. Subsequent pulmonary macrophage phagocytosis and lysosomal enzyme digestion of the coated dusts was modelled in vitro by incubation with phospholipase A2 for one hour. With increasing lipase activity, silica haemolytic potential was restored to native silica levels. Kaolin was retoxified to levels far in excess of native kaolin haemolytic potential. Elution, thin layer chromatography and phosphate assay of treated dusts indicate that most lecithin on silica is digested to lysolecithin and desorbed, silica retoxification being due to surface and adherent lysolecithin effects. Most lecithin on kaolin is not digested in the same time; that which is. results in adherent lysolecithin which is responsible for the kaolin retoxification. Digestion with phospholipases A2 and C together produces only weakly retoxified kaolin. Results suggest that surface adsorption properties which control the adherence of prophylactic surfactant distinguish the pathogenic potentials of quartz, kaolin and mixed dust.INTRODUCTIONERYTHROCYTE HAEMOLYSIS and pulmonary macrophage enzyme release assays show quantitatively comparable high cytotoxicities for both silica quartz and kaolin respirable sized dusts (BROWN, et al., 1980; DANIEL and LE BOUFFANT, 1980.) This contrasts with the strong potential for respirable quartz dust to induce pulmonary fibrosis and the much more limited potential of kaolin dust to do the same (MORGAN and SEATON, 1975).In an attempt to understand this anomalous situation, assays were performed on quartz and kaolin dusts incubated with dipalmitoyl lecithin emulsified in physiological saline, to simulate the initial contact of a respired dust with the pulmonary alveolar hypophase. The ability of kaolin dust to adsorb dipalmitoyl lecithin from physiological saline has been quantified (WALLACE, et al., 1975). Such lecithin treatment suppresses the cytotoxicity of both silica and kaolin to background levels (WALLACE, et a1.,1984).Surfactant coated detoxified dusts should then be phagocytised by pulmonary macrophages, incorporated into a macrophage secondary lysosome and exposed to hydrolytic lysosomal enzymes. Among these is phospholipase A2, which hydrolyses diacyl lecithin to lysolecithin. This was modelled by incubating lecithin treated dusts with phospholipase A2 in vitro to determine if the enzyme can digest the dust-adsorbed lecithin, and if the retoxification differs between the two dusts in a manner which might distinguish their pathogenicity."

Jan 1, 1988

"In sum, significant benefits to mine worker health have resulted and should continue to result from the synergistic scientific, engineering, and medical research in respirable dust. As always, an important objective is the rapid dissemination of the results of this research to industry. Video tapes and the Technology News series published by the United States Bureau of Mines (USBM) have been a very effective means of technology transfer. Individual no-cost subscriptions to the Technological News series are available from the Bureau of Mines, Branch of Technology Transfer, 2401 E St., N.W. Washington, DC, 20241.Two respirable dust conferences have been jointly sponsored by the Center, USBM, NIOSH, and MSHA. The proceedings from these conferences are titled:1. Coal Mine Dust Conference held in Morgantown, West Virginia on October 8-10, 1984 and2. Respirable Dust in the Mineral Industries: Health Effects, Characterization and Control held in University Park, Pa. on October 14-16, 1986.Copies of the proceedings from the first conference are available from the National Technical Information Service (NTIS):National Technical Information Service5285 Port Royal RoadSpringfield, VA 22161NTIS # PB86-169380Telephone Number: (703)487-4650Copies of the second conference proceedings, ISBN: 0-936712-76-7 (publication #3010), are available from ACGIH by writing toWilliam D. KelleyExecutive Director, A.C.G.I.H.6500 Glenway Avenue, Building D-FCincinnati, Ohio 45211Telephone Number: (513)661-7881During the period 1984-1987 more than sixty-four (64) papers and publications have been produced by the Center researchers. These publications have appeared in scientific journals and have been presented at national and international symposiums and meetings. A list of these papers, organized by topical headings, has been included in this publication.The generic center maintains a reference center that serves as a clearinghouse for technical information for the generic area and supplies reports on generic center accomplishments."

Nov 1, 1988

By R. H. Sprute

The Federal Bureau of Mines performed laboratory tests using direct current to dewater and densify fine-grained coal sludge in order to alleviate disposal problems and lead to recovery of high energy value often present in this waste. The laboratory tests described in the main body of the report were performed on thickened underflow (no flucculant added) from a northern Appalachian coal preparation plant. Solids in this slurry was very fine with 65 percent of the particles less than 0.1 mm in diameter. A variety of application procedures tested is exemplified by a test in which a soupy slurry (55 percent dry-weight moisture content) was converted into a firm dense material with a 20-percent dry-weight moisture content. These results were achieved in 3 hours with current density of 3.7 amp/ft2 and a power expenditure of 35 kwhr/yd3. The treated material has an average heating value of 10,400 Btu/lb. Varying current density, electrode configuration, and placement depth makes application of the treatment flexible. Two other types of sludge were tested briefly--thickener underflow from a southern Appalachian coal preparation plant with flocculant added, and sludge from an acid mine drainage treatment plant. The underflow responded well to the treatment, but response of the sludge from the acid mine drainage treatment plant was poor.

Jan 1, 1976

By R. V. Ramani, R. Stefanko, G. W. Luxbacher

Computer input data for an operating mine is developed on the basis of a detailed ventilation survey which includes air quantity, air quality, pressure loss and fan performance measurements. Quantity measurements must be reviewed extensively and assumptions made about leakage quantities and airflow paths. Pressure measurements must be reviewed and developed into a pressure gradient for the mine system. Air quality measurements are used to determine methane sources and amounts. Finally, the fan test data is used to develop the correct fan characteristic curve. Quantities and pressure losses for each branch in the system are used to calculate the branch resistances which are then utilized in the ventilation simulator to model the mine system. QUANTITY BALANCE The quantity of air coming into a mine based on field measurements will rarely equal the quantity exiting the mine, even if allowances are made for methane or compressed air input to the system. The same statement can be made for airflow through any isolated part of the mine ventilation system such as individual working section or main aircourses leading to an area isolated from the rest of the mine. The reason for the apparent discrepancies is the accuracy of the indicated quantities which in turn is based on the accuracy of the individual velocity and area measurements. Even with measurements following the guidelines described in the previous section on quantity measurement, this error can only be minimized but not eliminated. As a result the ventilation system must be carefully balanced so that, for any loop, the quantity in plus any methane or compressed air injection will equal the quantity out. The continuity of flow described by the balanced system must approximate the

Jan 1, 1977

By Clete R. Stephan, Mark J. Schultz, William A. Slivensky, Eric S. Weiss, Kenneth W. Jackson

he Pittsburgh Research Center (PRC)~ and the Mine Safety and Health Administration (MSHA) are participating in a research program to evaluate the strength characteristics and air leakage resistance of seals and water trap designs for use in underground coal mines. This program is being conducted at PRC's Lake Lynn Laboratory near Fairchance, Fayette County, PA. Seals designed with a 40-cm-thick polymer (polyurethane) and aggregate core between two dry-stacked (no mortar) concrete block walls (coated on out by sides) withstood a 138-kPa pressure pulse while maintaining acceptable air leakage rates. Similar seal designs utilizing a 97-cm-thick, 91-kg/m7-density, polymer-only core did not survive; however, a 5 1 -cm-thick, 203-kg/mi-density, polymer-only core seal successfully withstood the explosion pressures. Evaluations of cellular concrete seal designs have shown that a two-pour slurry injection technique did not adversely affect the strength of the 1.2-m-thick seals when subjected to a 138-kPa pressure pulse. Two seal designs utilizing low-density cementitious block have also been evaluated with successful results. In addition to seal strength tests, various 15- and 30-cm-diam U-shaped water trap pipes and a water trough design were evaluated under explosion conditions and were shown to be inadequate when evaluated under worst-case conditions. Simple modifications to the various water trap designs were successfu1 in preventing the passage of explosion flame through the trap.

Jan 4, 1996

By Paul W. Jeran, Michael A. Trevits, William P. Diamond

In this U.S. Bureau of Mines study, production trends have been analyzed for 82 gob gas ventholes on 7 longwall panels in the Lower Kittanning Coalbed, Pennsylvania. Cumulative production from individual holes was found to vary considerably, ranging from 0.03 x 106 to 10.1 x 106 m3. Peak production rates were generally about 0.03 x 106 to 0.06 x 106 m3/d, but rates over 0.10 x 1@ m3/d were observed. The variability of gas production from individual holes can be attributed to several factors, including completion practices and problems, the extent of fracture development in the strata above the extracted panel, water production, and location on the panel. Of particular significance is hole location. Holes on the ends of the panels, where overburden strata are in tension because of the support of the surrounding pillars, were generally the highest and longest producers. This observation led to the experimental placement of gob gas ventholes in the zone of tension along the margin of a panel, instead of in the traditional centerline location, which is in compression. Analysis of 7 months of gas production data indicates that the experimental near-margin holes produced 77 pct more gas than did centerline holes on the same panel.

Jan 1, 1994

By V. A. Marple, K. L. Rubow

"In our laboratory several impactors have been developed in the past which have penetration characteristics that approximate that of the ACGIH or the British MRC respirable curves. In these impactors the large nonrespirable particles are collected on an impaction plate of a multiple round nozzle stage where the nozzles are of different diameters. The principle for designing a respirable cut impactor is quite simple in that the respirable curve is divided into two or more segments and the nozzles are designed with the correct diameters and number of nozzles to have collection characteristics with 50% cutpoints at the center of each segment. The particles not collected on the impaction plates are then collected upon a filter. These particles represent the respirable fraction of the aerosol. Therefore the respirable curve is approximated in a stepwise fashion with the approximation becoming better as the respirable curve is divided up into increasing numbers of segments. It has generally been felt that three segments is satisfactory for most cases.A new version of the respirable impactor has recently been developed in our laboratory. This impactor approximates the ACGIH respirable curve in three steps at a flow rate of 30 liters per minute. However, unlike previous models where all of the particles larger than the three cut points designated by the three steps are collected upon one impaction plate, a separate impaction plate is now used for each of the three cut sizes. To approximate the respirable curve in three steps, the cut sizes must be 2.2, 3.5 and 5.8 microns diameter. Therefore, on each of these stages the particles collected will be the mass of particles that are larger than these three cut sizes. By determining the mass of particles collected on each of these three stages plus that on the after filter using Gravimetric techniques, some information can be obtained on the size distribution of the aerosol being sampled. Furthermore, the impaction plates of the three stages are rotated and the nozzles are placed in such a position such that a uniform deposit is obtained on each of the impaction plates. Therefore, the deposits collected are suitable for X-ray fluorescence analysis or other types of analysis where a uniform deposit is required."

Jan 1, 1988

By R. L. Anderson

Mechanical cleaning of bituminous coal in the United States was begun about 1875, with plants in western Pennsylvania and Illinois. The United States Geological Survey began to record the quantity of washed bituminous coal in 1906; and the series was carried forward to 1923, except that no data were collected, for 1922. This statistical work was transferred to the Bureau of Mines in 1925, and the collection of data on mechanical cleaning was resumed in 1927. Data collected before 1927 include only the coal that was washed at the mines and do not include that cleaned by pneumatic methods at the mines and that cleaned at central washeries operated by consumers.2/ The total bituminous coal washed in 1906 was less than 10 million net tons. In 1927, the first year for which complete figures are available for all types of mechanical cleaning, 28 million net tons of bituminous coal were cleaned in the United States.

Jan 1, 1951

By T. H. Ueng, S. D. Thompson, Y. J. Wang

"INTRODUCTION There is considerable interest among mining companies and government agencies in finding new ways to better control the generation and dispersion of respirable coal dust. Mine face ventilation generally has been considered the most effective tool for lowering the concentrations of respirable dust. Unfortunately, only a limited amount of research has been undertaken to determine the relationships between the various face ventilation parameters and the dust dispersion patterns. If these relationships are better understood, more efficient ways of controlling dust generation and dispersion may be evident. A practical and economical way to gain more in-depth understanding of these relationships is through scale model studies. Past research (1, 2, 3) has substantiated that scale models can be successfully used in studying ventilation parameters provided that geometric, kinematic, and dynamic similitues are maintained.To better understand face ventilation and dust dispersion, a 1/5 scale model of a room and pillar mine face was constructed. This model was then used to conduct experimental investigation on two ventilation parameters. The parameters which were examined included the line brattice distance from the face and the air quantity. The values of these parameters were varied in numerous experiments so that their effects on dust dispersion could be measured.The experiments of this study were unique in two ways. First, two different substances were used to simulate the respirable coal dust. Experiments were conducted with a tracer gas (methane) serving as the dust simulation substance. They were then repeated with an actual dust (Arizona Road Dust) replacing methane as the dust simulating substance. In previous scale model studies, the dust simulation substance has been limited to a tracer gas such as methane. The validity of using a tracer gas to simulate dust is not clearly known yet. The other unique thing about these experiments was the number of points measured for methane (or dust) concentration. Twenty five points in a grid arrangement were measured during each experiment of this study. The number of points measured for concentration in other studies has generally been very small (often 2 to 4). It is difficult to obtain an accurate assessment of how the ventilation parameters are effecting dust dispersion when only 2 to 4 points are measured."

Mar 1, 1989

By Thomas J. Peters

The U.S. Bureau of Mines studied the 63,9SS-acre Hanson Lakes study area, including the Ten Mile-East and part of the Ten-Mile West RARE II areas, plus additional acreage, all proposed at times for Wilderness designation. The study was part of a Idaho Land Assessment Program with the Idaho Geological Survey and the U.S. Geological Survey, to provide minerals information for land-use decisions, and ensure domestic mineral supplies. The area is at the north end of the rugged Sawtooth Range and includes parts of the Sawtooth National Recreation Area which is closed to mineral location. The Copper Mountain. Elk Mountain, and Observation Peak mineralized areas are in the study area, but only Copper Mountain is open to claim location. It is on the trans-Challis fault zone and contains Tertiary granite which is favorable for mineral deposits of gold, beryllium, niobium, REE (rare-earth elements), tin, molybdenum, copper, silver, and lead. Identified resources are 1.9 million tons of flake graphite at Elk Mountain, but much more graphite occurs in the vicinity REE occurs in 18 black sand placer sites along the lower reaches of study area streams just outside the study area, on Cape Horn Creek, Marsh Creek, and lower Valley Creek flood plains, and at one hydrothermal site near Observation Peak. Hydrothermal REE is commonly low in? by-product thorium. a radioactive disposal problem. Many advanced REE applications enhance the quality of life, and future uses in superconductivity may reduce energy consumption. Seventeen lode, one geothermal, and 11 placer prospects were examined. Workings totaled about 20 adits, one shaft, several open cuts, and numerous small pits. Approximately 500 mining claims have been located or relocated in the study area, including a 200-claim block for disseminated molybdenum.

Jan 1, 1992

"As stated earlier the primary goal of the Generic Mineral Technology Center for Respirable Dust is to reduce the incidence and severity of respirable dust disease through advancing the fundamental understanding of all aspects of respirable dust associated with mining and milling and the interaction of dust and lungs. While initial work was directed to coal dust the charge to the dust center has been expanded to include diesel particulates and asbestosis, the latter of deep concern not just to workers in the mineral sector of the economy but also to the general populace.A major facet of Dust Center research has been the analysis and documentation of comprehensive research protocol and procedures that are appropriate state-of-the-art in the various areas of respirable dust. In addition to definition of standardized research protocols and procedures which would be utilized by center personnel for uniformity and reproducability there is a considerable need for utilizing standardized respirable dusts in experiments with consistent, reproducible characteristics which simulate those of actual mine dust. This respirable dust needs to be available in large quantities for a wide variety of research uses that include animal and medical experiments. The dust must be free of the lubricating oils and grinding wheel contaminants that are frequently encountered in laboratory generated dusts.The holistic approach to establishing standardized protocols and procedures applicable to the five major research areas of the center is presented in Figure 5.In one hypothesis, range in coal volatility is considered to be a major causal factor in the incidence and severity of pneumoconiosis. Therefore a suite of characterized standard respirable dust samples have been prepared for researchers from coals representing the western (high volitile A bituminous), central (medium volatile bituminous) and eastern (anthracite) mining areas of Pennsylvania. Quartz, limestone (rockdust) and kaolin clay samples, representing important mineral constituents of coal dust have also been prepared.A suite of medical investigations have been developed utilizing small and medium size animals as well as non-human primates in a variety of dust/lung interaction projects which will be discussed in the next section. A number of respirable dust sampling and dust generation methods have been investigated and selected techniques utilized for both in-mine and in-laboratory research investigations. These will also be discussed in more detail later. A wide range of respirable dust size, chemical and mineralogical analyses have been investigated, standardized and documented for use in various research investigations.This interaction and documentation of various respirable dust sample procedures, animal and medical tests, sampling and dust generation methods, plus size, chemical and minerological analysis applied in the five major areas of research investigation have served to create a very favorable synergism and rapid technology transfer in the respirable dust center."

Jan 1, 1988

By Ernest R. Rodriguez, Allen D. Look

"INTRODUCTION The underground mine of the Miami Copper Co. has operated since 1927 without a fatality from blasting or the handling of explosives. To improve safety and efficiency, electrical blasting has been used exclusively since 1934. During the period January 1, 1934, to December 31, 1948, inclusive, over 4,000 tons of explosives were used to produce 60,925,071 tons of ore with 896,760 feet of development footage and 2,591,788 square feet of undercut area.The purpose of this paper is to recount the company's precautions to insure safe handling of explosives at this operation, where safety involves careful planning rather than ""trial and error.""GENERAL INFORMATIONThe Miami Copper Co. operates on underground mine in a large, low-grade, Porphyry copper deposit near Miami, Ariz. The deposit contains numerous fractures and planes of weakness, which contribute to ease of working the ore bodies by the block-caving method of mining.An individual stope-caving method is used with stoles 150 feet by 200 to 300 feet and 30- to 50-foot pillars between stapes. After the stope is undercut, the ore is drawn through the draw raises on the grizzly level, and thence through the transfer raises to the ore chutes on the haulage level.Access to the mine is by four active shafts, three of which are primarily for ventilation. No. 5 shaft is used for both hoisting and service. There are four operating levels in the mine. The elevations of the grizzly levels are governed by the contour of the bottom of the ore body and therefore vary in different locations in, the mine.Grizzly levels are on the 850, 900, and 975 levels. The 1,000 level is the haulage level. This mine operates in very low-grade ore and requires economical handling of large tonnages safely and efficiently."

May 1, 1950

Enhance the critical skill of hazard recognition among miners by providing quality training that can help jot performance and lead to a higher degree of safety in the workplace. Background In mining, as in many other occupations, the safety of the worker depends on his or her ability to recognize hazards in the workplace. Some of the information needed by the miner for recognizing potential areas of danger is available in the form of visual cues found throughout the mine. One aspect of the dynamic mine environment it which the task of hazard recognition is critical for al workers is that of ground control. Regardless of job responsibilities, every worker is continuously exposed to roof rib, and floor hazards. Fatality injury data for the "underground coal" segment of the mining industry continue to show that about half of all fatalities are due to falls of ground each year. It is hypothesized that some of these accident, can be prevented if miners are better able to recognize visual cues that forewarn of potential roof and rib problems.

Jan 1, 1992

By Joseph A. DeCarlo

This publication presents a tabulation of oven-and beehive-coke plants in the United States as well as pertinent statistical data on the number, capacity, kind, and condition of the ovens. Coke is an essential raw material in pig-iron production and the coal-chemical materials produced during the coking process are used to manufacture fertilizers, paints, plastics, synthetic rubber, explosives, detergents, nylon, pharmaceuticals; dyes, and many other products necessary to the high standard of living in this country. In table 1 the oven-coke plants in the United States on December 31, 1959, are listed. This shows the name and address of the company, location of the plant, classification or type of ownership, number and type of ovens, annual coke capacity, and the coal-chemical materials produced. The "furnace" plants I are those owned by iron and steel companies and most of them are integrated with blast furnaces to facilitate transportation of raw materials for steel making. Furnace plants represented 87 percent of the total coking capacity and their average annual capacity was 1. 3 million tons. The "merchant" plants are those associated with chemical companies, gas utilities, as well as those that produce metallurgical, industrial, and residential-heating grades of coke and coal-chemical materials for sale on the open market. These coke plants are smaller than furnace plants and in 1959 their average coke capacity was only 520 thousand tons annually. On December 3l, 1959, there were 54 furnace and 20 merchant oven-coke plants in existence in the United States.

Jan 1, 1960

By H. B. Cooke

In connection with its researches on the crude petroleums of the United States, the Bureau of Mines has made a particular study of apparatus for the distillation of hydrocarbon mixtures. While this study is still incomplete it has already resulted in the development of considerable laboratory and semi-plant equipment, motet of which has been described in various publications of the Bureau. The laboratory apparatus (Hempel distillation) and method gives satisfactory comparative results in the laboratory examination of crudes and have been found applicable to crudes of all types, but the agreement of laboratory and plant distillations is not as close as might be desired. This is due, in part, to limitations in size and construction of the laboratory apparatus. Some refiners claim that the Bureau of Mines' laboratory method (Hempel distillation3) for distilling crude petroleum, does not show the full gasoline content of the oil, while others have stated that it indicates more gasoline than can be obtained from the crude commercially. This difference of opinion among refiners results largely from the great variation in stills used and methods of operating them. The Bureau's experience has shown that crude oils from different fields vary widely in character; in fact, that it is not yet possible to classify crude's adequately on the basis of their Down chemical and physical characteristics. As a result of the differences that exist among crudes, and of the difficulty of designing refinery equipment, no standard practice has yet been adopted for the commercial distillation of petroleum, and ma" types of stills are used in the refineries of this country. Although many factors enter into the design of equipment and the development of commercial practice in refining of crude oil, there

Jan 1, 1924

By J. M. Oestreich

Supercritical water (sew) Is being tested for commercial use 1n several organic extraction systems but little work has been done on the extraction of metals from minerals. This lack of information prompted Bureau of Hines (BOM) research into the sew treatment of minerals. As a result, this research project is intended to serve mainly as a starting point for further experimentation. A simple flow-through reactor was built out of high pressure tubing and used to treat minerals with SCU at 400? C and 3500 to 7000 psi. The research produced four main conclusions: (1) carbonates of copper, iron, and lead convert to oxides; (2) most iron minerals showed alteration to oxides with some iron dissolution; (3) valuable trace elements including nickel, chromium, and others leached to some extent from sea minerals along with some calcium, iron, silicon, and sulfur; and (4) treatment of sulfides extracted elemental sulfur and resulted in several alteration reactions, though with the exception of cinnabar and the iron bearing minerals, the metals in sulfides were mainly insoluble. Surface alterations on many of the minerals show significant changes have occurred in the minerals even when only minor extractions were detected. These surface effects may be very important when used in conjunction with flotation processes since the sew treatment may selectively enhance or suppress a mineral's floatability.

Jan 1, 1989

Three types of communication systems have become popular in solving communication requirements underground: Loud-speaking pager phones, carrier current phones, and magneto ringing phones. Basically, all three are simply single-channel party line systems. Although these systems are quite reliable, the single channel creates a variety of problems. For example- 1. Since no call is confidential, messages are sometimes purposely made vague, especially if accidents or safety topics are being discussed. 2. A potential user must literally "wait in line" until the channel becomes clear for his use; thus, when foremen have to wait to call in reports or supply requests, this single chan-nel creates a serious productivity bottleneck. 3. In many large mines, there are independent branch lines that must be tied together by a dispatcher, adding further delays to the system. To solve these problems, some mines have installed other phone systems-mostly commercial dial phones in industrial enclosures that offer extra channel capacity and private line features. Others have installed a system that combines both dial- and page-phone features in a single unit. Although these do represent improvements, they do not truly solve the overall problems that face modern mines. Besides extra channels, a communication system should have the following features to enhance productivity and safety: 1. A means of paging a roving miner to alert him that he is wanted on the phone. 2. Wireless-to-wired system interconnects by which a miner can talk on the wired phone system by using a remote portable radio. 3. Remote monitors that alert personnel when there is a toxic or explosive gas buildup. 4. Control interfaces that allow remote control of fans, pumps, or other devices. 5. Transmitters and receivers that can serve as emergency links. 6. Loopback that allows an alternate path of communications if the main path is cut. This chapter focuses on equipment and methods to meet the special communication needs of individuals in various places of the underground mine. The communication requirements can be broken down into four categories: 1. The mine entrance (shaft communication). 2. Permanent and semipermanent locations (shop areas, lunchroom, crusher stations, etc.). 3. Mining areas (the room-and-pillar sections, longwall faces, block caving areas, etc.). 4. Haulageways (tracked trolley haulage, diesel, belt haulage). Methods of implementing systems to meet the communication needs of these areas are described in sections 3.2 through 3.5. Section 3.6 discusses methods of satisfying special communication requirements that exist. Major topics in this category include communications with roving personnel, the isolated miner, and motorman-to-snapper communications. Emergency communication systems are described in section 3.7.Detecting and

Jan 1, 1984

By Bruce T. Olenchuk, Wils L. Cooley

Electrical grounding is essential for the safe operation of power systems. A low-impedance path to ground is necessary to prevent the possibility of dangerously high potentials in human work areas. If for any reason this ground connection becomes faulty, a serious hazard may exist. One reason for faulty ground connections is ground bed corrosion. Corrosion of electrical ground rods has plagued the power industry and appeared in coal mine power systems. This paper will investigate ground rod corrosion, its cause, and possible solutions. Included is an evaluation of various ground rods for their ability to resist corrosion under stray current conditions. -The first known study of X-it3 Rod Corrosion is also presented.

Jan 1, 1979