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To reduce needless paging of persons by all phones in a mine or mill, while retaining all-location page capability. Approach Standard pager phones of any manufacturer are modified to include the option of selective calling and message holding. How It Works All commercial mine pager phones presently rely upon voice paging via a loud-speaker. When a page is initiated, every phone in the system broadcasts the audible voice page, even phones in locations where the desired person could not possibly be. The advantage of this scheme is that whole-mine paging occurs. The disadvantage is that persons soon begin ignoring pages because they occur all the time, and most are for someone else. Also, it requires considerable battery power from all phones making it necessary to change batteries very frequently, even in phone locations where personnel rarely go. In addition, if a voice page is made and not heard, there Is no way to leave the message. Therefore, persons who at a later time come near a phone, have no way of knowing a page was made and was not acknowledged. This results in situations that often have a direct bearing on safety and productivity.

Jan 1, 1980

By Austin B. Clayton

The magnetite deposits of the Big Ore Bank, in Lincoln County, N.C., were mined during the reconstruction period following the Civil War. The country rock at the Big Ore Bank property consists of micaceous schists and schistose quartzite with a few beds of dolomitic marble. Magnetite occurs with micaceous chlorite schist and is often so schistose that it is hard to distinguish from associated minerals. A magnetic survey by the North Carolina Geological Survey indicated several magnetic anomalies that appeared to justify exploration. The Bureau of Mines drilled 10 diamond-drill holes, totaling 4,493 linear feet, to delineate the deposits. More than 500 sludge samples and 119 core samples were collected for analysis. The project was begun in November 1943 and completed in April 1944.

Jan 1, 1948

By J. R. Thoenen

During the year 1927 the Bureau of Mines, at the request of a number of quarry operators, undertook to make a study of quarry operating costs in order to determine average costs for certain operating conditions and to suggest a model cost accounting system for quarry operations. A detailed questionnaire was prepared and mailed by the bureau to all quarries on its records as employing ten or more men in 1926.

Jan 1, 1929

By Leonard Obert

This report describes the development of a dynamic strain gage and a companion amplifier and recording camera -an apparatus designed to pick up and record the strain waves produced in rock by a nearby explosion. Also included in the report is a discussion of the relationships connecting the strain with the displacement, velocity, and acceleration for both plane and spherical waves. The proposed tests for which the strain gages were intended required making measurements in solid rock, a factor that necessitated the development of a gage that could be inserted and anchored in a small-diameter diamond-drill hole. The restriction on the diameter of the drill hole is required so that the presence of the hole in the medium will not influence the propagation of the strain wave. The gage should respond with fidelity to the frequencies present in a wave pulse generated by the nearby detonation of a small quantity of high-velocity explosive. Preliminary tests showed that this frequency range extends from 200 to 10,000 c.p.s. or greater. Also, the gage should be capable of measuring strains ranging from a few micro-inches per inch to several thousand micro-inches per inch. Other desirable design specifications included a low gage output impedance to permit the use of long cables, and a low gage cost, particularly in view of the fact that for the final design none of the gages can be recovered from the medium.

Jan 1, 1949

By C. H. Elder, Maurice Deul

A 5-hole pattern was drilled from the surface at a site near Oak Grove, Jefferson County, Ala., to degasify the gassy Mary Lee coalbed in advance of mining. Gas and water production was monitored for 1 year, 4 months to allow gas flow to stabilize fully. A thickened water stimulation treatment was designed and applied in one hole of the pattern to evaluate this degasification technique for the Mary Lee coalbed. A gas production rate of 70,000 ft3 /day after stimulation treatment indicates that the use of vertical boreholes coupled with hydraulic fracturing in advance of mining the Mary Lee coalbed would provide for more rapid degasification and could provide a possible source of natural gas.

Jan 1, 1974

By Theodore Christos

The Bureau of Mines sponsored an investigation of the thermal oxidative degradation characteristics of selected ingredients employed in the formulation and manufacture of conveyor belts. This work was done to supplement similar studies of samples from finished conveyor belts and thus provide basic data for correlation of the potential toxic behavior of a finished belt with that of the individual ingredients. This report covers the study of (1) basic polymers (styrene-butadiene, neoprene), (2) reinforcing fibers (Nylon 6,6, Dacron, viscose rayon), (3) flame-retardant plasticizers (tritolyl phosphate-isomeric mixture, tri-p-tolyl phosphate, tributyl phosphate, tris (dichloropropyl) phosphate), (4) plasticizers (diphenylphtha1ate, di-(2-ethylhexyl) sebacate), and (5) a vulcanization accelerator (2-mercaptobenzothiazole).

Jan 1, 1977

By A. D. Bauer

For several years the Bureau of Mines has conducted surveys to determine the changes in motor gasoline being sold throughout the United States. The present survey shows that far the districts in which samples were collected, the average gasoline is becoming more volatile instead of less so, as is sometimes supposed. This year's gasoline is much more volatile than that sold two years ago, and it has a somewhat better distillation range than last summer's samples. A comparison of the average figures for several years, shows that motor gasoline is also becoming more uniform in character. The large seasonal change is disappearing, but ?winter gasoline', still has a lower initial boiling point than "scanner gasoline". This difference in volatility is made intentionally to facilitate starting the motor in cold weather. The end point shown in the present survey is slightly lower either than that of last winter or of the summer of 1921.

Jan 1, 1922

By Robert C. Ellman

Stockpiles containing 2.3 million tons of lignite constructed in the period 1948-56 in conjunction with the construction of Garrison Dam on the Missouri River demonstrate successful stable long-term storage of lignite. Uniform and thorough compaction of each of the I-foot-thick layers by which the piles were constructed produced a bulk density of 70 Ib/cu ft. Air penetration into the stockpiles was restricted to a degree that prevents spontaneous heating or deterioration of the stored lignite, A continuing record of observations beginning with stockpiling operations in 1948 has been accumulated, This includes periodic fuel analysis, analysis of pile gases, and measurement of pile temperatures on the first large stock-pile, pile 5. This report describes the stockpiling method, the changes in heating value, pile gas composition, and pile temperature and summarizes observations from 1953 to 1964, Data accumulated attest to the stability of the stored lignite. The variation of the average heating value of periodic pile-depth samples is only 160 Btu/lb (11,990 to 11,830) on the moisture" and ash-free (maf) basis during almost 10 years of storage. Temperature levels of the pile interior are progressively decreasing. At pile surface, cyclic variations occur with the season. The only problem encountered with the large stockpiles is wind and water erosion of the pile surface. The partially successful control measures used are described.

Jan 1, 1967

By John Owens, Marc Endicott, Hamid Maleki

This study presents a historic overview of the role of mobile roof support (MRS) technologies in improving stability and worker safety and presents the results of recent field evaluations of the MRS load rate monitoring device and other remote deformation-monitoring techniques. Field studies were implemented at two sites in cooperation among researchers from the National Institute for Occupational Safety and Health (NIOSH), Maleki Technologies, Inc., and J. H. Fletcher & Co. The objective of the field programs were to (1) study the interaction between MRS’s and coal mine strata and (2) develop and test suitable monitoring systems for assessing roof and pillar stability. An MRS consists of a roof canopy, four hydraulic cylinders, a caving shield canopy, and associated electromechanical systems mounted on crawler tracks. The machines are controlled by radio from a remote location and operate on self-contained power units. Typically, MRS’s have capacities of 5,340 and 7,120 kN (600 and800 tons). In comparison to posts, an MRS is capable of maintaining the yield load after significant amounts of roof-floor deformation. Because the mining cycle is accelerated, MRS’s help reduce the potential for time-dependent roof falls. MRS performance has been monitored in the laboratory under controlled static loading conditions and in the field under deep, two-seam mining conditions. Laboratory studies have quantified support capacity and system stiffness as a function of machine height. Field investigations have focused on determination of optimum operating conditions and development of warning systems that indicate excessive load on the machine and/or impending roof-pillar stability problems. Analyses of field data show that roof instabilities are influenced by (1) pillar failure, (2) pillar yielding, (3) mine seismicity, (4)geologic structures, and (5) panel layout designs and mining practice.Pillar yielding and failure (unloading) and seismicity can be conveniently monitored by the load rate monitoring device, but for consistent detection of roof falls, additional deformation measurements directly within the cuts are needed.

By G. T. Krempasky

This report covers the installation and evaluation of lb reinforced concrete sets, 6 in each of 3 mines in the Goeur d'Alene mining district, Shoshone County, Idaho, and is the second of a series to determine the feasibility of a more permanent type of mine support. Closure measurements, where applicable, were made periodically of the concrete-set installations and were compared to the initial cross section of the sets. A different method of blocking was used at each test site; at one test site the type of blocking was changed several times during the test. Results from each test site are reported separately. No attempt was made to compare the cost of the concrete installations with the cost of other types of support used in the district. Such an evaluation of permanent types of support would require a longer period of time. At this time, tests are not complete enough to determine the applicability of underground concrete supports. However, results to date tend to confirm the general opinion that precast concrete mine supports could be used to advantage in openings that require support and must have long life, especially where decay of timber is an important factor.

Jan 1, 1963

By L. B. Pankratzt

The heat content above 298.15° K of ferroelectric lithium columbate (LiCbO3) was measured to 1,770° K. The Curie temperature was determined to be 1,450° K, the melting point 1,540° K, and the heat of fusion 16.94 kcal/mole. Heat content and entropy increments have been tabulated for the temperature range from i98.15° to 1,800° K. Heat contents are also given in equation form.

Jan 1, 1966

By Stephen Krickovic, J. E. Carpetta, T. D. Moore

Air quantity-pressure and methane concentration surveys were conducted by the Bureau of Mines in accessible portions of an area being pillared in a Pittsburgh coalbed mine in West Virginia. These included two mined-out and three active butt headings and a bleeder system. The particular mine workings were started in virgin coal directly from a set of main headings; the main reason for the study was the difficulty usually encountered in adequately bleeding the gobs under such conditions. Although the two separate return airways in each active butt heading and the North and 1 Left bleeders contained acceptable methane concentrations (0.01 to 0.78 percent in the butts and 0.73 to 1.0 percent in the bleeders) with significant total methane removal (109 cfm in butts and 631 cfm in bleeders), there were relatively large areas in the gobs with possible minimal airflows. This condition appears to have developed from lack of systematic regulation of the airflow across the gobs and appears to indicate the existence of considerably more methane in the probably low flow areas in the gob.

Jan 1, 1973

By John D. Sullivan

The present article is one of a series which is being prepared by the Southwest Experiment Station of the United States Bureau of Mines in cooperation with the Department of Mining and Metallurgy, University of Arizona, Tucson, Ariz., of papers dealing with factors involved in the leaching of copper ores. A knowledge of the time required to dissolve the various copper minerals present in ores, as well as of the consumption of leaching reagents is very desirable, because with the decrease of the Nation's total tonnage of sulphide ores increasing attention is being given to the recovery of copper by leaching methods from low-grade disseminated ore containing both oxidized and sulphide minerals. As leaching has already been applied with success and profit, this study was undertaken to determine certain fundamental characteristics that are applicable to all ores suitable for leaching.

Jan 1, 1929

By F. Cherpereel, R. Gabillard, J. P. Dubus

We present an electromagnetic method taken from the well known radiogoniometer that allows us to locate at the surface of the ground the vertical axis of a magnetic antenna transmitter buried at a depth h in the earth. The method and the equipment achieved are called R. E. P. E. (Relevé Electromagnétique de Points Enterrés). They are daily used to accurately survey old quarries by using triangulation instruments at the surface of the earth rather than in galeries where the setting difficulties considerably reduce their accuracy and increase the work length. The results of several surveys allow us to give the optimum working conditions of the instruments and show that, when the transmitter is at a 20 meters depth, its position is known at the surface with an error lower than 1 centimeter. The power transmitter is of about 8 watts and we can find its location with an error smaller than 1 meter when buried at a depth of about 100 meters. This equipment may be successfully used for location of subsurface miners. The space surrounding the transmitter must then be free from ferromagnetic bodies.

Jan 1, 1973

By H. J. Heinen

This report summarizes preliminary research studies by the Bureau of Mines in electrowinning molybdenum directly from pure or impure molybdenum trioxide (MoO3) by fused-bath electrolysis in an open graphite cell without need of a protective inert atmosphere. A formulated electrolyte of the tertiary system containing 41.6 percent sodium pyrophosphate, 16.7 percent sodium tetraborat, 33.3 percent sodium chloride, and 8,4 percent molybdenum trioxide, by weight, electrolyzed at 1,000° C,, gave excellent results. Current density studies were made over a range from 20 to 260 amperes per square decimeter. Current efficiencies of 80 to 90 percent were obtained over the entire range. Yields up to 500 grams of molybdenum per kilowatt-hour were obtained. Higher current densities, however, reduced yields and produced a finer grained metal. The two most important facets in electrowinning molybdenum from MoO3, in an open cell, are temperature and electrode spacing to minimize or eliminate the formation of the suboxide MoO2, the major source of oxygen contamination. At temperatures of 1,000° C. and higher, together with the proper spacing of the electrodes, formation of oxides are practically eliminated. Molybdenum metal electrowon from pure MoO3 was 99.9 percent pure and contained 0,056 percent oxygen and 0,007 percent carbon. This metal, when arc-melted, had a Vickers hardness number of 175 and contained 50 parts per million oxygen and less than 10 parts per million carbon. Molybdenum metal electrowon directly from an impure MoO3 containing 90 percent MoO3 resulted in a metal of 99.8 percent purity.

Jan 1, 1961

Decrease dust concentra¬tions of longwall face workers by keeping them up¬wind of the headgate stage loader and crusher. Approach Direct the face airflow from tailgate-to-headgate, the direction of coal transport. How It Works Ventilation is the primary method of dust control on longwall faces, and the most effective ventilation control is to put workers upwind of dust sources. Recent ad¬vances in longwall dust sampling by the Bureau have shown that on some faces, the headgate crusher and transfer points are signifi¬cant sources of dust -some¬times making up more than half of the total dust to which the face workers are exposed. Also, when the air is coursed from head-to-tail, the relative velocity between the air and moving coal on the face conveyor can cause dust entrainment from the conveyor, particularly if the coal is dry. On the faces where these dust sources are a signifi¬cant problem, they may be eliminated by coursing the air from tailgate-to-headgate, provided that the mine roof is stable enough to permit the necessary intake of the tailgate along with an aux¬iliary intake at the headgate.

Jan 1, 1982

By Thomas V. Falkie, R. Venkataramani

The empirical nature of this investigation required measurements of variables under operating conditions in underground coal mines. The variables to be measured were based on the postulated character¬istics of the loading function, as described in the previous chapter. One class of variables presumed to influence the loading function are geological variables. Accordingly, the sites for data collection were selected in different bituminous coal seams at dispersed locations in order that variation in geological conditions would exist. Seven mines in central and western Pennsylvania and one mine in northern West Virginia were selected as data collection sites. Five different coal seams were represented by these mines. The remaining classes of variables - geometric, mechanical, and procedural - were measured as they occurred in the mines. A description of the measurements, and the conversion of these measurements to forms which could be-analyzed for effect on the loading function is given. Mining Dimensions At the underground working face, the following dimensions were measured: a. Thickness of coal excavated. b. Thickness of shale excavated. c. Total height excavated. d. Width excavated. e. Depth of penetration of each machine cut. With the exception of the last of these dimensions, all were measured

Jan 1, 1972

By R. L. Grant

Study of the ignition of firedamp by explosives and the phenomena that underlie it is one of the long-term investigations of the Bureau of Mines. This report is the third in e series by the Explosives Branch summarizing the progress made at Bruceton in this study. The first paper described preliminary work on small, carefully controlled cannon shots the second discussed the results of suspended shots.5/ In this paper, experiments are described and interpreted that extend and support the concept of ignition presented previously. ACKNOWLEDGMENT The authors wish to thank Bernard Lewis, former chief, Explosives and Physical Sciences Division, and Guenther von Elbe, former chief, Physical Sciences Branch, Explosives and Physical Sciences Division, for their guidance and constructive interest.

Jan 1, 1954

By H. W. Kilau

Thermodynamic calculations indicate that an electrochemical cell might serve as an analytical device for determining the composition of high-purity metals. An equation, readily derived, for the cell voltage, E, is as follows: [E I RT In F NFe unknown sample T of L NFe standard] The cell, however, must come to equilibrium, must be reversible, and must have no thermal effects or complicating side reactions whose magnitude is indeterminable. This Bureau of Mines investigation explores the feasibility of an electrochemical technique for the analysis of high-purity iron. Experiments were conducted using room-temperature aqueous cells and high-temperature molten salt cells. The room-temperature cells proved to be irreversible. The high-temperature cells utilizing FeCl2 and a eutectic mixture of KC1-LiCl were reversible, but did not attain a constant voltage necessary for analytical considerations.

Jan 1, 1963

By Edward L. Burwell

The Bureau of Mines investigated the use of dilute polymer in brine solutions to increase the efficiency of air in gas flooding model oil reservoirs. Slugs (0.23 pore volume) of 500 ppm polyacrylamide were injected into a model, consisting of a high- and a low-permeability core, that had been previously gas flooded to residual oil. Gas flooding was then resumed. Of the total gas volume injected, the percentage entering the high-permeability zone was greatly reduced after polymer injection but remained unchanged when slugs of water without polymer were used.

Jan 1, 1970