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By A. B. Hooker, L. C. IlsLey

"Field inspections and data relative to the use of rubber—sheathed trailing cables in mines show that much cable is ruined or its probable life shortened by being overheated in service.The length of cable required to make connection from a source of supply to a machine at the face workings may be 100 to 500 feet. As a rule, the cable is carried on a reel and unreeled as required; and thus in most cases some of the cable is not removed from the reel. The overheating generally occurs in that part of the cable which is left on the reel.Factors that determine the heating of trailing cables are:1. The size of the conductors in the cable.2. The maximum energy to be supplied through the cable, based upon the horsepower of the motor and the degree to which the motor is loaded.3. The voltage of the supply and the variation of the voltage at the receiving4. The time length of current flow and whether continuous or intermittent.5. The kind of current (direct or alternating).6. The amount of cable left on the reel.7. The type of cable used.8. The kind of reel used.In connection with an investigation of the general performance of rubber—sheathed trailing cables, the Bureau of Mines has made a limited study of some of these factors, including the following points:"

Jul 1, 1931

By J. R. Hauger, P. A. Romans, W. J. Niebuhr

With suitable instrumentation and techniques it is possible to determine the presence of tantalum in columbium to 20 ppm . This paper discusses the selection of X- ray spectrographic instrumentation and describes a technique for accomplishing the low level determination of tantalum . An ion- exchange method of separating tantalum from columbium is also described .

Jan 1, 1964

To pinpoint dust sources and to improve dust control on longwalls. Approach Use short-term gravimetric sampling to determine the severity of various dust sources, and to evaluate dust control techniques used in longwall mining. Short-term gravimetric sampling can be used to isolate dust levels produced by various dust sources. How It Works Traditionally, gravimetric samples have been collected over an 8-hour shift, yielding time-weighted, average dust concentrations. This method gives a good indication of the full-shift respirable dust exposure of underground workers, but is less than satisfactory for identifying dust sources, determining their severity, or for evaluating the effectiveness of dust control techniques. Short-term gravimetric sampling uses equipment available to all mine operators. Two individuals composing the survey team each collect multiple (three to four) gravimetric samples during selected segments of the mining cycle. Multiple samples are necessary to insure accuracy, and to obtain a valid average measurement of the respirable dust concentration when sampling for short periods of time (typically 20 to 30 minutes). The gravimetric instruments may be carried in a sampling package or in a "sampling vest." A fishing vest with four large pockets can be used for this purpose. The sampling pumps are carried in pockets and the sampling head assemblies arc hung across the front of the vest.

Jan 1, 1982

By Terry S. Cory

This report is a comprehensive summary of the results of the propagation measurements program conducted for the US Bureau of Mines under Contract H0366028. Data was gathered in the MF frequency range from a cross sample of six mines representative of the industry having typical wireless requirements. From the raw data which was gathered, a logical method of data reduction is presented which culminates in a set of average attenuation characteristics for all mines visited. These characteristics define a typical MF wireless system when the communication range requirements are known. Direct through-the-earth propagation and the range enhancement mechanism due to coupling on and off conductors are evaluated and related to the planning of a typical wireless MF communications system.

Jan 8, 1977

By A. Sainato, S. J. Kravits, G. L. Finfinger

This Bureau of Mines report describes and compares the procedures, capital investments, and operating costs of rotary and in-hole motor drilling techniques used to drain methane gas from the Pittsburgh Coal- bed in an underground mine located in southwestern Pennsylvania. A timestudy was conducted during the drilling of each of two boreholes, and the data were collated to serve as a base for comparing drilling procedures and operating costs. Findings indicate that drilling with an in-hole motor offers four advantages over rotary drilling; namely, an increase in drilling productivity, fewer worker-hours required, ease of maintaining vertical and horizontal bit trajectory, and less expensive drilling cost per foot of borehole.

Jan 1, 1985

By L. R. Willmott

An ethanolamine purification unit for removing carbon dioxide and hydrogen sulfide from Firscher-Tropsch synthesis gas was installed at the Bureau of Mines synthetic liquid fuels demonstration plant at Louisiana, Mo. The unit was a surplus Radford Girbotol unit from the Missouri Ordnance Works modified for a capacity of 90,000 std. cu. ft per hour of synthesis gas at 450 p.s.i.g., operating pressure. The hydrogen sulfide loading of the feed gas was specified at 500 grains per 100 cu. Ft. The unit was designed by the Girdler Corp. and installed by the Koppers Co. Initial operations were conducted far 11 days in May 1951. Thereafter 7 additional runs were made, varying lo duration from 8 to 54 days. The last run was terminated on May 29, 1953, the total time the Plant wars in operation being 219 days.

Jan 1, 1956

By R. P. Adams

Because of the extreme interest in materials with high melting temperatures and the advantages offered over the powder route for making high-density material, arc-melting and centrifugal-casting methods were investigated for preparing shapes of hafnium carbide with and without excess carbon. Highly satisfactory equipment was constructed and efficient operating procedures were established. Also, methods for preparing consumable electrodes and shrink-tolerant graphite molds were developed. Although crack-free hafnium carbide (6.3 weight-percent carbon) shapes were not made, coherent castings containing 9 to 13.5 weight-percent carbon were produced; the same compositions were shown to be resistant to thermal shock. Selected physical and chemical tests were performed on castings chosen for investigation by chemical and nondestructive inspection techniques. Electrical conductivity and thermal expansion measurements were made. Measurable oxidation of all the compositions studied was observed to start between 500° and 600° C. Attack by nitrogen, however, did not occur until temperatures exceeded 2,000° C. A linear relationship of the logarithm of the diamond pyramid hardness to the temperature was noted. Considerable scatter of the bend-rupture strengths at room temperature and of the tensile strengths up to 2,000° C was found. However, at the latter temperature and above, a definite relationship of strength to temperature was observed and some ductility was noted.

Jan 1, 1968

By Allen D. Look, Stanley M. Walker, Van Fleet. Leonard A.

"INTRODUCTION The hazards to be encountered in temporarily or permanently abandoned underground mines, quarries, and open pits are numerous, and hardly a year goes by without several reported cases of fatal or serious injuries occurring to unwary people who enter these old mines. Persons visiting mining areas for the first time, tourists, and young people, especially, proceeding in the spirit of adventure common to youth or to the venturesome have suffered many such accidents during exploration trips. The possibility of salvaging salable or usable equipment prompts men and boys to go into old mines, some through ignorance of the attendant hazards, but some jeopardize their lives hopeful of gain (in some cases pitifully small), thinking the hazards are not dangerous and that they can ""get away with it.""Persons fall into unprotected holes, some seek shelter from storms under high banks, and quarries and open pits are often chosen as places for recreation, picnics, swimming, etc; all such uses of these places are likely to be hazardous and to lead to accidents, frequently fatal.These hazards are known to men in the mining profession, and the danger to the public is realized by most of them. A solution to the problem has been sought at many mining meetings, and it is recognized that complete prevention of entry into old mine workings and surface mining areas is the ideal solution, but this, unfortunately, is not always practical; better education of the public, particularly children, should help to reduce the number of such accidents and will be effective in direct proportion to the extent and vividness of such education."

Aug 1, 1948

By S. J. Gerdemann

In support of its objective to improve mine safety, the Bureau of Mines has searched for better materials and systems to anchor roof bolts. TIlis report describes a study on the effects of mine waters upon accelerated gypsum, one of the materials under consideration. The accelerated gypsuw dissolved at an appreciable rate relative to an assumed 10-yr life span of a roof bolt. Surface orientation, initial ion concentration of a dissolving solution, and flow rate of the solu-tion had substantial effects on the dissolution rate. Factors such as water-cement ratio, accelerator content, wax capsule additions to the gypsum in cartridge-installed bolts, surface area, temperature, and curing duration had little effect. In an actual roof-bolt environment, dissolution will occur in static solutions to the solubility limit of gypsum (~2 giL) and cease, result-ing in minimal damage; but in flows of unsaturated solution as slow as 1 L per month, a loss of up to 10 pct will occur in 2 yr. Since miners cannot readily measure the flow or ion concentration of static-appearing water at every roof-bolt site, all such water must be assumed to be pure and flowing. It is recommended that gypsum-bonded roof bolts be confined to dry roofs only.

Jan 1, 1983

By Rose L. Ballard

This chapter summarizes data on crude nonfuel mineral production for the United States, its island possessions, and the Commonwealth of Puerto Rico. Included also are the tables that show the principal nonfuel mineral commodities exported from and imported into the United States and that compare world and U.S. mineral production. The detailed data from which these tables were derived are contained in the individual commodity chapters of Volume I and in the State chapters of Volume II of this edition of the Minerals Yearbook. Although crude mineral production may be measured at any of several stages of extraction and processing, the stage of measurement used in this chapter is what is normally termed "mine output." It usually refers to minerals or ores in the form in which they are first extracted from the ground, but customarily includes the output from auxiliary processing at or near the mines.

Jan 1, 1985

Improve the safety of mine workers by developing a sensitive ground-fault relay system capable of detecting and isolating low level ground faults and thereby minimize the danger of electrocution. Approach Inadvertent, direct contact with energized conductors in underground coal mines is a major cause of electrocutions. Although relay systems designed to protect workers against such fatal accidents do exist in some industries, there are no effective ground-fault-sensing relay systems that address the special problems presented by power systems designed for U.S. mines. The Bureau of Mines conducted research to design and construct a sensitive ground-fault relay for use with low-voltage, alternating current (ac) mine electrical systems. Such a relay, sensing current leakage or faults in an electrical system, would send a trip signal to a circuit interrupting device which would then shut down power.

Jan 1, 1986

By J. O. Winget

Phosphonic acid and iminodiacetic acid chelating resins were investigated to assess their potential as selective ion exchangers for separating lanthanide elements and yttrium . The affinity of phosphonic acid resin for lanthanides increases with increasing atomic number , and that of iminodiacetic acid resin for lanthanides increases with atomic number to a maximum for element 62 and then declines with atomic number throughout the remainder of the series . Elution sequences of the elements with mineral acid eluants corresponded favorably with equilibrium data , whereas the elution sequence obtained with chelating eluants was proportional to the relative values of the stability constants of the chelating agents with the lanthanides . Separation of lanthanide mixtures into groups of light and heavy elements with iminodiacetic acid resin appears feasible .

Jan 1, 1964

By R. W. Stahl

Increasing use of continuous miners, especially the boring type, has focused attention on the inadequacy of face ventilation in coal mines. The bulk of the machine, the rapid advance of working faces, and the increased liberation of methane from the larger expanse of freshly exposed coal surfaces have created ventilation problems that were unknown with conventional mining equipment. Ignition of gas, especially that caused by machine bits striking hard rock or pyritic inclusions, have increased at an alarming rate. As the mines penetrate beds under thicker cover at an ever-increasing rate of face advance, this problem will probably increase unless face ventilation is improved. A previous survey, described in Bureau of Mines Report of Investigations 5414, Auxiliary Ventilation of Continuous Miner Places, disclosed that auxiliary fans with tubing generally improved circulation of air and removal of gas at the face. The study here reported attempts to examine, face ventilation at various mines and to note any plan or innovation of. air coursing that industry might adopt to reduce the danger of gas ignition. ACKNOWLEDGMENT The mines visited were very cooperative in the study-and-generously supplied any data requested.

Jan 1, 1960

By V. R. Spironello

The Bureau of Mines is conducting studies of the slags related to ferrous technology to evaluate acceptable substitutes for the auxiliary flux, mineral fluorspar, in foundry operations. This work is directed toward the Bureau's goal of minimizing the Nation's dependence on scarce and critical minerals Comparative basic practice cupola (18-inch-ID) trials were made to evaluate a waste material called "used potlining," which contains significant levels of fluorine, sodium, and aluminum in various compounds. Used potlining is recovered from alumina reduction cells after its useful life, and was supplied by the Aluminum Co. of America (Alcoa) to the Bureau for evaluation. The material in the lump and pelletized form (with limestone) provided extremely fluid slags based on visual observation during cupola operation. No adverse effects were found on cupola performance, metal and slag chemistry, the environment, or mechanical properties of the castings produced. Fluorine recovery in the slag was equal to, or higher than, that of fluorspar; fluorine losses to the scrubber water and solids were lower. The acidity of the scrubber Hater was somewhat neutralized. No difference was observed in furnace-refractory attack, as determined by the level of magnesia in the slag and visual inspection. The recovery of sodium in the slag, presumably as the oxide, significantly increased slag fluidity, suggesting that less than equivalent fluorine may be required. There was no contamination of the gray iron by the aluminum from the used potlining. Used potlining was completely satisfactory as a substitute for fluorspar in cupola ironmelting.

Jan 1, 1981

By David P. Conover

The U.S. Bureau of Mines (USBM) has developed a computer-assisted Ground Control Management System (GCMS) for near realtime evaluation of underground coal mine ground conditions. The GCMS combines existing mine-monitoring system and sensor technology with automated computer analysis techniques to enhance the acquisition, analysis, and display of geostructural data. The GCMS, which combines mine structure data with other information, such as geologic conditions and mine layout, has provided information on mining-induced stress transfer and pressure buildup associated with several ground control events. The GCMS collects and analyzes shield-leg pressure, ground pressure, and strata movement data to evaluate the structural behavior of an active Western U.S. Iongwall coal mine. Field data are transmitted over a dedicated phone line to the USBM Denver Research Center (DRC) mine monitoring laboratory, 240 km (150 miles) from the mine site. Real-time collection, processing, and analysis of mine structure and shield pressure information has proved to be an effective method for near-face ground conditions while mining progresses. The GCMS provides the mine operator with information to rapidly identify and manage potentially hazardous ground conditions while mining is in progress.

Jan 1, 1994

By J. H. East, D. Harrington

Fires in metal mines have resulted in some of the worst disasters in American mining history insofar as loss of life is concerned. One fire caused the death of 163 miners and individual less spectacular fires have cost the lives of scores of workers. Metal mines are often very deep, and the men working on numerous levels far removed from direct communication with the surface. In many instances they cannot be warned quickly of an emergency or a mine fire by telephone or other usual method of communication, or by messenger, flashing lights, gongs, sirens, or whistles. Telephones are not paricularly effective as a means of warning unless placed at all strategic points and with attendants always on duty; though telephones well placed have a definite value in any well-pla.mied emergency procedure in mines of all kinds. Messengers are slow and men working in remote parts of a mine would not receive a warning quickly enough. Most metal mines are not electrically lighted, except at or adjacent to shaft stations and in principal haulageways, and this limits the effectiveness of flashing lights. Electric gongs and sirens or whistles have been tried as warning signals, but the sound is quickly deadened and does not travel upward into the stopes, especially those of an extensive volume. Shutting off the compressed air is by no means satisfactory as a warning, as not infrequently it is stopped accidently, so that it loses its value as an alarm. The introduction of water into compressed air lines is undesirable as a fire warning and necessitates considerable care, especially in deep mines; pressure-reducing valves must be provided to reduce pressure that otherwise would break connections or split the pipe. A quick, effective method of warning miners underground of the existence of an emergency requiring them to leave the mine immediately, such as a fire on the surface or underground, is provided by the introduction of stenches in the compressed-air lines. This method of warning is by no means experimental, inasmuch as it has been used successfully for many years in

Jul 1, 1943

By John W. Cole

Ore deposits in the? vicinity of Philipsburg, Mont., have been mined continuously since discovery of the Hope mine in 1865. Although originally famed chiefly for its silver production, since about 1917 the district has been the only important producer of battery-grade manganese ore in the United States. Also, it has produced substantial quantities of zinc ore and during World War I and World War II contributed notable amounts of manganese for metallurgical consumption. Nearly the entire production of base metal ores has been mined from the outcrop area of? a dolomitic limestone bed that plunges beneath overlying beds of limestone and shale northward from the outcrop area. The Hope silver mine, with a production record of over $4,000,000, was in one of the overlying limestone beds about 3,000 feet north of the base-metal producing area and about 1,000 feet vertically above the projected downward position of the dolomitic bed that has produced the base-metal ores. Furthermore, the Hope ore bodies were controlled, in part at least by east-west fractures similar to those that controlled the deposition of the base-metal ores.

Jan 1, 1949

By Ralph H. Espach

The value of careful fractionation in the manufacture of petroleum products is recognized more and more by petroleum refiners. Recent studies have shown that the quality of the products depends largely on the type of fractionating equipment and on the care used in operating the equipment. For example Rue3 has shown that careful fractionation of pressure distillate will greatly reduce the amount of chemical treatment necessary to produce finished gasoline. The advantages of the combination of pipe still and bubble tower in obtaining good fractionation are well recognized in the petroleum industry. However, the equipment designed in the past has in general been much too large for convenient laboratory use. The present paper describes a continuous-distillation apparatus for the laboratory study of fractionation. This apparatus has given very satisfactory results in the study of different crude oils and petroleum products. A discussion of the theory and action of bubble towers has not been given, as this subject has been discussed previously by Cooke and Rue4. It is believed that the distillation curves of the products obtained from this apparatus show clearly its capabilities.

Jan 1, 1928

By T. L. Hebble

The Bureau of Mines investigated a hydrometallurgical procedure to recover Co, Ni, and Cu from an electrolytic zinc industrial copper filter cake. The copper filter cake is presently unmarketable or of low value because economic and environmentally acceptable processing technology is lacking. Research by the Bureau of Mines has developed a multistage process for recovering or recycling over 93 pct of the Zn, Cd, Cu, Co, and Ni from this material. The stages involved are (1) wet sizing, (2) H2S04 leaching of undersized material, (3) H2S04-Mn02 leaching of H2S04 leach residue, (4) selective precipitation of As, Cu, and Co-Ni products, and (5) precipitation of manganese for recycling to the leach circuit. The final process residue is only 1.6 wt-pct of the initial cake and consists of lead sulfate.

Jan 1, 1981

By Robert S. Sanford

This paper deals with truck haulage methods and costs at one of the many open-cut mines that are replacing rail haulage with heavy-duty trucks. At this mine, ore is trucked to a crushing plant, centrally located within one of the open-cuts. The requirements for efficient low-cost truck haulage are: Good trucks designed for heavy loads, adequate truck maintenance, smooth roads, and well-trained truck drivers The weighted average cost of hauling a long ton of ore to the crusher and the waste to the dump was reduced from $0.1993 in 1948 to $0.1114 during the last half of 1949, his corresponds to a cost per ton mile of $0.0864.

Jan 1, 1952