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By John N. Murphy

INTRODUCTION It's a pleasure to be with you and to share in this opening session for the 27th Annual Institute on Mining Health, Safety, and Research. As we come together today, I would like to reflect for just a moment on the past Institutes. Much of the progress in Mine Health and Safety has been the subject of presentations and discussions at the previous Institutes, either by identifying the issues, proposing techniques to overcome the problems, or presenting new findings to address important issues for the mining industry. May I extend our thanks and congratulations to VPI and to the planners and organizers of all of these Institutes for their important contributions to our mutual goals of improving mine health and safety. In the time available today, I would like to accomplish two objectives: 1. Provide my assessment of the current status of the Mining Health and Safety Research Program; and 2. Share with you the continuing need and direction for the Mining Health and Safety Research. MINE HEALTH AND SAFETY RESEARCH TODAY Mine Health and Safety Research was conducted formerly at four geographical locations within the USBM, specifically: Pittsburgh, Spokane, Twin Cities, and Denver. Although the Twin Cities and Denver Centers were closed, we have been successful in relocatingfmaintaining much of the core competencies to conduct a responsive, multidisciplinary Mine Health and Safety Research Program. The current staff at Pittsburgh and Spokane directed toward Health and Safety Research totals 397. This includes Lake Lynn Laboratory, about 60 miles southeast of Pittsburgh, where large-scale mine fire and explosion research is conducted. With the closures and transition we have worked to maintain the core competencies necessary to address Health and Safety issues. In some cases we have made arrangements to provide the requisite core competencies through external organizations. An example is the reassignment of the diesel particulate instrumentation capability from Twin Cities to Pittsburgh. In the case of diesel emission control, due to the cost of relocating laboratories and the lack of the appropriate skills at Pittsburgh or Spokane, the emission control laboratory is now being operated in Minneapolis through a contractual arrangement with the University of Minnesota.

By L. C. IlsLey

A specially recommended cable is a rubber-sheathed cable that has met the minimum performance requirements for cables as set forth in Schedule 20. The first in the series of recommended cables was listed September, 1930, by an ad- vance notice published as Information Circular 6375 which described the conditions under which the cable tests were made. Since that time six additional cables have met the test re- quirements and have been specially recommended. The complete list of specially recommended. cables is as follows: Specially recommended-cables Cable Symbol No. Hazacord No. 2 BM1 Stranding 19 x 7 Hazacord No. 3 BM2 do. Hazacord No. 4 BM3 do. Super-service No. 3 BM4 7 x 19 Super-service No. 2 Super-service No.. 4 BM5 do. BM6 do. Super-service No. 4 BM7 7x 7 Manufacturer Hazard Insulated Wire Works (division of the Okonite Co.) Do. Do. Rome Wire Company (division of the General Cable Corporation) Do. Do. Do. The cables listed were all twin (parallel duplex) cables having outer belts or cov- erings of approximately -inch high-grade rubber compound, and have the same general appear- ance and relative dimensions as the types of twin cables in general use. The cables were tested under conditions designed to show their approximate perform- ance under mine conditions. Only twin-type cables have met these test conditions. Although the recommended trailing cables are much better and safer for mine use than other cables and withstand being run over by a 7-ton car, they should not be considered as 100 per cent safe. The 7-ton car test represents the minimum limit requirement effective at present under Schedule 2-C, but the test car operates on a straight and level track, and thus does not represent the more severe conditions of mine use such as might result from uneven and curved tracks.

Mar 1, 1931

By Clarence O. Babcock

This report describes the results of a Bureau of Mines investigation in which an elastic inclusion, orebody, or mining system is replaced for purposes of analysis with an imaginary effective inclusion of rectangular shape that encloses the region. This effective inclusion has averaged physical properties that are directly related to the average inclusion stresses. The results were in excellent agreement with those predicted by Donnell's theory (2)2 for an isotropic elliptical inclusion in a state of plane strain for all height-to-width ratios and for all degrees of inclusion hardness from very soft to very hard. The results are exact for an isotropic circular inclusion and provide an easy method of evaluating the stresses obtained by cylindrical inclusions in boreholes when the Poisson's ratio for both host and inclusion equals 0.25 for plane strain or 0.333 for plane stress. The theory was also used to predict the average stresses in 48 finite-element models of single transversely isotropic inclusions of ovaloid and rectangular shape. An interesting and useful observation from this work was that the forces on elliptical inclusions in the x and y directions, produced by applied uniaxial stresses in the y and x directions, respectively, were equal in magnitude but opposite in sign when the applied stresses were equal. This occurred when the plane strain condition was used with a Poisson's ratio of 0.25. The practical usefulness of the method is given by treating a variety of mining problems: (1) The average stresses in an orebody of irregular shape; (2) the average stresses in single-level room-and-pillar mining systems; (3) the average stresses in multiple-level room-and-pillar mining systems; (4) the effect of mining sequence on the average stresses produced during mining; (5) the stresses in cylindrical borehole plug related to host rock stresses as a function of plug hardness; and (6) methods for simplifying finite-element analysis of complex structures.

Jan 1, 1974

By Ronald D. Hill, Elmore C. Grim

The cost of reclamation can vary widely, depending on the primary objectives of the restoration activities. statistics in this study originated from State files, publications, and personal communications relating to restoration and pollution control measures for previously mined lands (orphan lands) and active mines. Reclamation of orphan lands is generally considered a public burden and constitutes an economic problem. All work reported here was completed under government contract, by the lowest bidder, with money coming from State and/or Federal funds. Cost would have been substantially lower had the reclamation been concurrent with mining. Several persons connected with some of the projects have observed that costs could probably be reduced by at least one half, if the reclamation had been conducted along with the mining. The expense of clearing and grubbing of volunteer vegetation, disposal of buried trees and brush, loosing of compacted spoil, and re-establishing access to areas could be saved. In addition, a contracting firm doing the work for a government agency would have mobilization costs and receive a profit. Mining companies also are profit conscious and would consider these costs in anticipating their profits (e.g., overhead would be less if reclamation is integrated with mining). The data presented here should serve as a guide for estimating and determining cost ranges, however, it should be recognized that variations exist. Adjustments may be necessary from the standpoint of physical conditions, economic conditions, price changes, and more restrictive requirements of recent surface mining laws. Reclamation conditions, procedures and successes in the eastern United States, particularly in Appalachia, have no bearing on conditions to be expected in the western United States. The situations are wholly different. Reclamation in the West differs from th t in the East, primarily because of aridity especially a during the summer months 1). Because of the many variables and differences between reclamation in eastern and western areas, they will be discussed separately.

Jan 1, 1974

By Sean Gallagher

Study Design. A split-plot experimental design was used to evaluate the influence of posture, trunk angle, and rotational velocity on peak torque output and myoelectric activity during maximal trunk extension maneuvers. Objectives. To determine whether the kneeling posture alters extension torque capabilities in isometric and isokinetic exercises as compared with standing. Also, to ascertain whether recruitment of trunk muscles is modified by such a postural change. Summary of Background Data. Factors such as workplace geometry may force workers to adopt awkward or unusual postures in the performance of manual tasks. An understanding of the limitations placed on strength in unconventional working postures is crucial to the proper design of jobs. Methods. Twenty-one healthy male subjects (mean age = 36 years 7 SD) performed 12 trunk extension exertions in standing and kneeling postures. Isometric tests were performed at 22.5°. 45°, and 67.5° of trunk flexion. isokinetic tests were done at three velocities: 30°/sec, 60°/sec, and 90°/sec. Electromyographic data were collected from eight trunk muscles to assess muscle recruitment under each condition. A prior; orthogonal contrasts were specified for analysis of both torque and electromyographic data. Results. The kneeling posture was associated with a 15% decrease in peak torque output when contrasted with standing; however, no concomitant change in trunk muscle activity was evident. Trunk hyperflexion (isometric tests) and increasing rotational velocity (isokinetic tests) were associated with reduced torque in both postures. Trunk muscle activity was primarily affected by changes in trunk angle and velocity of contraction. Conclusions. A reduced extensor capability exists in the kneeling posture, despite equivalent trunk muscle activity. The similar activation patterns in both postures suggest that the strength deficit does not result from alterations in trunk muscle function. Rather, it may be the consequence of a reduced capability to rotate the pelvis in the kneeling posture, due to a disruption of the biornechanical linkage of the leg structures. [Key words: electromyography, isokinetic, isometric, low back pain, posture. strength1 Spine 1997;22:1864-1872

By Charles L. Parsons

The United States produces all of the fuller's earth used for re- fining petroleum within its borders. On the other hand, most of the fuller's earth used in bleaching edible oils has been imported from England. Recently a few of the refiners of cottonseed oil have begun to utilize domestic fuller's earth, whereas others have been unable to substitute it successfully for English earth in their practice. Many samples of American earth distinctly superior in bleaching power to the English earth have come to the attention of the Bureau of Mines. For these reasons an investigation of the mining, preparation, and use of fuller's earth in this country, especially in its application to edible oils, was conducted in order to ascertain why our own raw material has been deemed inapplicable to our needs. During the calendar year 1912, according to figures of the United States Geological Survey," there were imported into the United States 1,970 tons of unground fuller's earth, valued at $11,619, and 17,139 tons of ground fuller's earth, valued at $133,718, these values being based on the wholesale market price at the port of origin. The addition of transportation charges, commissions, etc., make the price to the American refiner $14.50 to $16 per ton. Accord- ing to the latest figures compiled by the United States Geological Survey, the United States in 1912 produced 32,715 tons of fuller's earth, valued at $305,522, or $9.34 per ton, at the mine. Most of this domestic production was from three plants in Florida and one in southwestern Georgia and was used almost wholly for decolorizing petroleum. A small amount from other localities was used in the refining of edible oils. No figures definitely differentiating fuller's earth from other clays are kept in regard to our exports, but it is certain that several thousand tons of domestic earth was exported to Germany, and it is also true that German refiners of edible oils have

Jan 1, 1913

Homans [1950] offered a working definition of group that is useful for this research: "We mean by a group a number of persons who communicate with one another often over a span of time, and who are few enough so that each person is able to communicate with all the others, not at secondhand, through other people, but face-to-face." This chapter begins with a discussion of the group concept in reference to the hypothesized escape groups mentioned earlier. It then moves to an examination of analysis techniques used by the authors. Finally, the subjects themselves are profiled according to their demographic characteristics. The Nature of Groups Warriner [1956] took a realist approach to understanding groups: "(1) the group is just as real as the person, but (2) both are abstract, analytical units, not concrete entities, and (3) the group is understandable and explicable solely in terms of distinctly social processes and factors, not by reference to individual psychology." Warriner's realist position merely holds that "group" occupies a different domain in which it is no more or less concrete than "person." At this group level the unit of analysis will be those relations that indicate social rather than individual behavior. It is possible to investigate these group properties empirically-if a researcher avoids confusing conceptual entities with concrete ones. Most people seem to accept that group attributes must somehow be inferred, but think personal attributes will be directly manifested, requiring little or no interpretation [Snizek 1979]. In other words, nobody would equate physical components of an underground working section with the actual work group, yet social scientists (as well as laypeople) very often confuse real individuals with notions of the person. In actuality, neither groups nor persons are directly disclosed to the senses; both are inferred by experience and observation. One can "see" a group just as clearly as one can "see" a person, given the proper perspective from which to do so. It is necessary, in developing this perspective, to begin with a sound definition of the thing being examined. Besides communication, or more generally, social interaction, Homans [1950] included three other components of group makeup. "Sentiment" is characterized as the feelings people tend to form about one another when they interact often. These feelings include not only friendliness and dislike, but attitudes such as approval or disapproval. A "norm" is an idea, held in common by group members, that specifies how people ought to behave in given circumstances. In lay terms, norms are simply those informal rules individuals abide by in order to get along together in social situations. Finally, "activity" refers to those things persons do with others. In work groups, as an example, many of the activities are cooperative and goal-directed.

Jan 1, 2000

By L. C. IlsLey

One of the details which the engineers observe closely in conducting tests on explosion-proof type equipment at the Pittsburgh experiment Station of the Bureau of Mines is the construction of covers and their means of fastening. These covers are of particular concern from a safety standpoint, because they are very liable to be frequently disturbed for the purpose of making inspection or repairs to internal parts of motors, controllers, etc. When depended upon to permit frequent inspections it is desirable from a practical operating standpoint that the cover be easily and quickly removed and replaced. The position that been taken by the Bureau of Mines is that the questio of ease with which covers will permit inspection should be determined by the mamu- facturer and the user. If the scheme used requires considerable effort, as in the removal of several bolts, it has been assumed that the one going to all this trouble to get the covers off could be trusted to put the cover back in place properly, especially as the approval plate generally calls specific attention to this point. Where a cover is simply screwed in place, fastened by a single bolt, or secured by a hing in or other similar arrangement, the bureau has not been willing to assume that the, cover would in all cases be properly fastened and has required further security by means of a lock or seal. In the course of its investigations the bureau has had occasion to inspect and test five types of covers as follows: (1) Covers having two plane surfaces bolted together. (2) Covers having two plane surfaces held together by lugs, clamps, or other means besides bolts. (3) Covers which have screw thread and fit a similar thread in the compartment. (4). Covers having plane surfaces with the addition of a tongue-and-groove joint at about the center of the plane surface and in general secured by hinge pins or similar means of fastening. (5) Covers in the form of an annular ring accurately fitted to a motor shell which can be rotated around the shell, and thus make easy access to inspection openings in the shell and rotated back again to effectively seal these openings. Tests. have also been made of large bolted covers having a smaller and more accessible cover within the large one, which could be opened for inspection purposes.

May 1, 1930

By A. M. Dale, J. Standeven, B. Evanoff

Tool manufacturers continue to incorporate new designs to the internal mechanism of tools in order to decrease the vibration that is delivered to the hand during operation. Modification of some tools to minimize tool vibration is not easily resolved through internal tool design. For this reason, vibration damping materials applied between the tool and the hand are a simple alternative. The damping materials may be applied to the area of the tool directly contacted by the operator or in a glove containing a vibration absorbing pad. These interventions are developed specifically to damp vibration but are not necessarily produced and tested under the same work conditions that a company may expose their workers. Therefore, it is important to test the value of the proposed interventions for the specific applications. This study evaluates the effectiveness of anti-vibration interventions currently in use at a local manufacturing company. Methods The design of this study evaluates the vibration energy produced at the tool handle and from the back of the operator’s hand. Each operator performed a series of fastener installations in metal using several interventions and one series with no intervention as a control. Four of the interventions were gloves containing anti-vibration material and the fifth intervention was an anti-vibration material wrapped around the tool handle. The protocol for wrapping the tool handle was developed and is part of the equipment procedure at this manufacturing company. Test conditions mimicked production work conditions including similar materials, fasteners and technique for installation. Vibration values were collected using 3 tri-axial accelerometers with one firmly glued to the tool handle close the hand grip as recommended by ISO 5349. A second accelerometer was placed on the top of the pistol shaped tool. The third accelerometer was attached to the back of the hand close to the third knuckle using double sided tape. Results Preliminary results for 3 volunteers show a difference between the vibration values of the control condition (mean hand vibration on bare hand = 1.77 Gs) compared to all of the interventions (p=.0001 using Mixed Procedure, Tests of Fixed Effects). The graph below shows individual trials for each subject for each condition. Glove 3 with the air bladder insert shows large variability between subjects (Range = 0.84-3.33 Gs). The other interventions show much less variability both within subjects and between subjects indicating consistent response with use of the intervention.

Jan 6, 2006

By E. D. Gardner

"The Bureau of Mines receives many inquiries concerning favorable areas in which to prospect for gold, procedure to be followed, equipment required, and allied subjects. This circular has been prepared for use in reply to these inquiries.Interest in gold mining and prospecting for gold remains steady. From time to time many people take to the field to search for new gold deposits. A large percentage of them have had no previous experience in prospecting for lode gold; this paper has been written with the hope that it might assist these newcomers.A majority of the metal mines in the United States have been discovered by qualified prospectors who were searching for valuable minerals at the time. Chance, however, always has played a large part in finding mineral deposits. Some of the discoveries of the past were made by men on other errands, such as rounding up burros or hunting game. Accidental discoveries of ore bodies have been made in building roads and trails and in excavating for mine struc¬tures. Evidence of ore has been brought to the surface by burrowing animals and by ants; gold found in the craws of fowl has led to discoveries of deposits. Important discoveries have been made by men who had no knowledge of rocks or minerals; on the other hand, many ore bodies have been found by experienced prospectors, sometimes after hundreds of untrained men had already passed over the ground.The prospector who carries on his work diligently and intelligently is of course more likely to be rewarded for his efforts than the lazy or unintelligent worker; nevertheless, it is obvious that if valuable deposits are not present at the place being prospected none will be found. Conscientious and painstaking efforts to trace gold to its source usually disclose nothing more valuable than some narrow, unworkable seams; however, many deposits that were developed into profitable mines were found by this method of prospecting. Although some prospectors have made several lucky strikes, many others have spent their working lives searching for gold without finding anything worth while. Probably only one prospector out of several thousand ever finds anything worth developing. Moreover, only 1 out of every 300 or 400 properties developed becomes a profitable mine.Prospecting was begun in the Western States in the fifties as the miners looked for the source of gold found in placers. The search for gold has been continuous since that time; the number of prospectors in the field at any one time, however, has varied greatly. Except in some desert regions, practicallyall of the placer fields now being worked were discovered by old timers; more-over, most of the important gold districts were found by early prospectors. Important discoveries of lode mines, however, have been made from time to time. Most of the area in the mining regions of the West has been searched many times by prospectors, and nearly all of the easily found deposits have been located, but it is reasonable to expect that new gold mines will continue to be found. Most of the future discoveries undoubtedly will be of deposits that do not outcrop. Prospecting for such deposits requires considerable digging.Several important discoveries were made in 1934. One of these, the Rogers-Gentry gold mine at the edge of Antelope Valley in Los Angeles County, Calif., was found by an experienced prospector on an old patented homestead a number of miles from the nearest producing mine. The initial discovery at this mine was an iron-stained, decomposed, silicous limestone outcrop, with no vein structure evident at the surface, near a small, barren quartz outcrop and a water seep. Another discovery, the Silver Queen gold mine, in the same general region and near Mojave, Calif., was found by an experienced miner on an open fraction 400 by 1,400 feet in size between two old properties that were thought to have been worked out years ago. The Silver Queen discovery was made as the result of finding a"

Feb 1, 1950

By J. Feldman

This report contains a description of the distillation laboratory at Bruceton, Pa., which was established to aid in the separation and identification of the products produced in the synthetic liquid fuel processes under study there. Compounds present in synthetic liquid fuels may include aliphatic from C1 to C60 or greater. Alcohols, ketones, esters, aliphatic carboxylic acids, saturated hydrocarbons, olefins, and diolefins are all found in Fischer-Tropsch products. Coal-hydrogenation products contain, in addition to aliphatic compounds, a large proportion of naphthenic material and aromatic compounds ranging from benzene to coronene; in addition, appreciable quantities of tar bases and tar acids are present. In designing the laboratory, therefore, provision had to be wade for the greatest amount of flexibility and versatility. A great deal of standardization of basic equipment had also to be designed to permit interchange of parts and services.

Jan 1, 1951

Reduce exposure of longwall face workers to respirable dust generated during the advancement of roof supports. Approach Identify and implement current water-application and improved support-movement practices used to lower support-generated dust. Defining the Problem Bureau studies have shown that on some longwall faces support dust can contribute over 30 percent of the respirable dust exposure of face workers. Conditions contributing to high levels of respirable dust generation during support movement are: depth of cover greater than 1,000 ft; immediate roof consisting of coal top or friable shales; and face-air velocities in excess of 500 fpm. Moreover, at most longwalls, supports are advanced on the intake-air side of the shearer as it travels with the airflow. This places the shearer operators, and in many cases the support movers, downwind of support advance, thus increasing their respirable dust exposures.

Jan 1, 1984

By A. T. Coumbe

The Bureau of Mines has compiled pipeline mileage every 5 years since 1926, with the exception of the war period 1941 to 1949. The present survey has been made to reflect the progress under mobilization of the petroleum pipeline industry where efforts have been made by the government to stimulate construction of those facilities that would best equip the nation for a possible major emergency. This report summarizes the total mileage change 1n petroleum pipelines for 1950 through 1952. In order to increase the value of the information gathered the reporting companies were requested for the first time to report not only the net change in mileage as formerly, but also all new and used pipe laid and the total taken up. This new information permits effective appraisal of the construction effort of the industry and relates it to steel requirements.

Jan 1, 1953

By C. M. McKinney

Sulfur content data from Bureau of Mines routine analyses of 1,060 United States crude oils were used with crude oil production data for the years 1956-66 to prepare tables and charts that illustrate the volume and percentage distribution according to sulfur content of crude oil produced in 10 geographical areas of the United States. Similar relationships for foreign crude oils based on analyses of 201 crude oils and production during 1966 are illustrated for Africa, Canada, Middle East, and South America. Tables are included giving field name, sulfur content, geologic name and age of producing formation, depth of producing formation, and production during 1966 for 882 United States crude oils and 201 .foreign crude oils. Between 1955 and 1966 the average sulfur content of crude oils produced in the United States decreased from 0.73 to 0.67 percent.

Jan 1, 1967

By John C. Edwards

Chapman-Jouguet detonation calculations were carried out for pentaerythri-tol tetranitrate (PETN), TNT, and ammonium nitrate-fuel oil (AN-FO) explosives using the compressibility form of an equation of state of hard spheres based upon Percus-Yevick (PY) theory, and a chemical equilibrium detonation code called TIGER. Similar calculations were also carried out with the Becker-Kistiakowsky-Wilson (BKW) equation of state. For PETN, the BKW equation gives somewhat better agreement with experimental values of detonation velocity and pressure. However, in terms of experimental temperatures and concentrations of the minor product species (NO), the predictions of the PY equation are shown to be more satisfactory. Similar comparisons of experimental and theoretical results for TNT and AN-FO indicate that the PY equation has general utility in predicting the detonation properties of condensed explosives at moderate loading densities (Po < 1.3 g/cm3).

Jan 1, 1974

By Parviz F. Rad

The Bureau of Mines conducted groove cutting experiments in marble, lime-stone, granite, and quartzite with a 7-inch disk cutter under a normal thrust of 7,000 lb. The values of muck weight per unit length, specific energy, cutting coefficient, and groove depth for each of these rocks were determined for groove spacings ranging from 0.1 to 4 inches, and from these results the values of optimum and critical spacing were computed" The results indicate that compressive strength may be used to predict some of the cutting characteristics of the independent grooves. Considering all the cutting characteristics, particularly those for the interacting grooves, Shore hardness, coefficient of rock strength, and torsional velocity correlate with cutting characteristics better than do other physical properties. Some of the field applications of the principles established in this report are identified.

Jan 1, 1974

This chapter describes the adverse health effects associated with exposure to respirable coal mine dust. Epidemiological studies of underground and surface coal miners in the United States and other countries are discussed. Also discussed are animal studies that add to our understanding of particle deposition and retention in the lungs and associated disease responses. This chapter emphasizes studies that (1) were performed since the passage of the Federal Coal Mine Health and Safety Act of 1969 [P.L. 91- 173], (2) used standardized methods of exposure monitoring and disease classification, and (3) investigated exposure-response relationships between respirable coal mine dust exposure and disease. Several published review articles contain further discussion of health effects studies of coal miners [Attfield and Wagner 1992b; Petsonk and Attfield 1994; Cotes and Steel 1987; Merchant et al. 1986; Morgan and Lapp 1976; Morgan 1975].

Jan 1, 1997

By Joseph B. Huvos

Said to be one of the world&apos;s most under-developed countries, Benin had a gross national product (GNP) estimated at $1 billion in 1980.2 Contribution of the mineral industry such as cement and limestone to the GNP was negligible, but exploration of mineral potential continued Minerals.-The United Nations Development Program (UNDP) conducted an investigation of three deposits from 1977 to 1980: Phosphates (Mekrou), gold (Perma), and chromite (Buem). A phosphate rock deposit containing about 4.5 million tons recover- able by opencast techniques was discovered. It was not known if the gold and chromite deposits were recoverable economically. Iron ore deposits of some 230 million tons near Loumbo-Loumbo are at present not exploitable because of lack of infrastructure in the northern part of the country. Geologic mapping with British and French assistance was also pursued in 1980.

Jan 1, 1982

By G. M. Wilemon

The Bureau of Mines conducted preliminary investigations on the use of an acid-alcohol leaching technique for recovering phosphate values from phosphate matrices. H2S04 and methanol were used as the leaching agents. Starting-matrix particle size and acid-apatite ratio were found to significantly affect the efficiency of phosphate leaching. Phosphate extractions of more than 80 pct were obtained when minus 200-mesh ore was used and the acid-apatite ratio was 8:1 or more. The iron and aluminum oxide impurities (R203) present in the crude acid products were monitored, and R203-P205 ratios are reported. Phosphate extractions in excess of 80 pct also were obtained when phosphatic clay wastes were leached. Typically, leach slurries filtered using test leaf filters ex-hibited filtration rates of 100 lb/(h·ft2) or more.

Jan 1, 1987

Provide a means to (1) rapidly disconnect a multifunctioning signal channel from a multichannel data collection system, (2) protect electronic devices from damage while causing the minimum amount of data collection disruption, and (3) operate electronic devices under gassy mine conditions. Background Data collection system instrumentation and cables are often located in hazardous areas of underground coal mines. As a result, frequent damage to the instrumentation cables occurs from roof falls, heavy equipment, and the relocation of air, water, and power lines. A similar problem exists in surface areas where cables and instrumentation can be damaged by animals and by vehicle traffic. Without a circuit-breaking feature, the damaged cables could cause instrumentation to be ruined, cause power supply failure, and otherwise disrupt data collection in some situations the lack of a circuit-breaking feature might cause an ignition in a methane atmosphere.

Jan 1, 1990