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By Terry S. Cory

This report covers magnetic field strength measurements vs range and frequency in low-medium coal mines. Both quasi-conductor-free and conductor-proximity areas were investigated. The program covered 5 mines, 4 seams, 6 measurement sets, and 3 geographic areas. The results have been summarized in terms of maximum communication range expected per seam and noise condition. Scatter gain is further explored as a simple measure of energy coupled to conductors.

Jan 6, 1978

By A. E. Wells

A critical study of the wet Thiogen process for extracting sulphur from the smoke of smelters is one of several investigations related to the general smelter-smoke problem that are being conducted under the direction of the Bureau of Mines. Part of the work done in the pyrometallurgical section of the cooperative metallurgical exhibit of the Bureau of Mines at the Panama-Pacific International Exposition during 1915 related to this investigation, and at the expiration of the exposition, the work was continued in the labora- tories of the Bureau of Mines in the Hearst Memorial Mining Building of the University of California, Berkeley, Cal., where a mining experiment station of the bureau has been established under the cooperative agreement with the University of California. Early in the spring of 1915, when plans were being made to co- operate with several metallurgical interests, the Thiogen Co. proposed to the Bureau of Mines that, along with the studies of various pro- posed methods for eliminating sulphur dioxide from smelter smoke, there should be included a study of the wet Thiogen process. In the study as outlined it was proposed to determine whether it would be technically and commercially feasible to use the, process for the recovery of elemental sulphur from the sulphur dioxide in waste smelter gases. Although there had been no large-scale work with the process, either in the laboratory or at a smelter, representatives of the metallur- gical and mining industry had shown considerable interest in the proposed method, and the desire had been expressed that a better knowledge of the possibilities of the process should be obtained. Thus, cooperation with the Thiogen Co. seemed justified by the in- terests of the metallurgical industry, and by the conservation promised by the recovery of a product of market value from what is otherwise a waste, and in some instances a serious nuisance. In accepting the responsibility for directing this investigation, the officials of the Bureau of Mines were necessarily free to conduct the work in the manner they considered necessary to determine the facts. It was also understood that any information obtained was to be made available to all who might be interested and might be printed in a Bureau of Mines report. To cover the cost of laboratory equipment and supplies, and the payment of salaries of assistants, other than Bureau of Mines employees, the Thiogen Co. in May, 1915, deposited with the cooperative metallurgical exhibit fund a sum considered sufficient to warrant starting the laboratory investi- gation. The origin and organization of this fund has been described by Clevenger and the author." In outlining the program for this investigation it was hoped that ultimately a small complete plant would be erected and the investi- gation center around the operation of the plant. However, pre- liminary to the erection of the plant, a laboratory study of the proc- ess was considered necessary, as the technical features of the process could be determined, it was believed, as satisfactorily on a smaller scale as on the scale first proposed. However, it was realized at the time that it would not be possible to determine so satisfactorily or definitely the commercial possibilities of the process on the scale of work adopted as in the larger operating plant. With this fact in mind it was planned that, if the study of the technical features on a laboratory scale gave sufficient promise of the process being commer- cially feasible, an operating unit should, if possible, be constructed later, and that more definite information concerning the commercial prospects should be determined. The investigations were started in June, 1915. In June and July work was confined entirely to small-scale laboratory tests, in which a careful study of the chemical reactions involved was made. In August, tests on a larger scale were started, and these were con- tinued until December, small-scale tests being made at the same time. On December 1, 1915, all work on the Thiogen process was discon- tinued temporarily, as the close of the exposition necessitated moving the laboratories. Work on the Thiogen process was started again in January, 1916, in the laboratories of the new mining experiment sta- tion at Berkeley, Cal., and was continued during the spring of 1916 until a point was reached where it was felt that the essential parts of the process had been carefully covered, and that some definite state- ments concerning the technical features and possibilities of the process, as given in this report, were warranted.

Jan 1, 1917

By John C. Edwards

Carbon monoxide (CO) sensors are used in mine fire early-warning systems. Experiments were conducted by the U.S. Bureau of Mines with six diffusion-type CO sensors to determine their response to a reference CO concentration under both static and dynamic flow conditions. Static experiments were conducted with 0.5 L/min flow of 16 ppm CO in N2 through 8-and 12-L chambers. Dynamic flow experiments were conducted in two environmental chambers: One had directional flow capability of 1 m/s, and the second provided moderately nondirectional flow as high as 1.8 m/s. Reference CO concentrations of 13.5 to 19 ppm in air were used for the dynamic experiments. The results of the static experiments demonstrated that the sensors consistently underestimated the reference gas concentration. The dynamic experiment results showed the sensors provided reasonable agreement with the reference gas concentration when directional flow effects were not considered. Directional flow effects were evaluated for two sensors. One of the sensors showed a strong dependence upon the relative orientation of the diffusion tube with respect to flow direction. The second sensor did not show a dependence upon flow direction. The sensors' directional flow effect is significant for their proper in-mine utilization.

Jan 1, 2010

To provide a means for rapidly evaluating proposed mine layouts in order to avoid potential hazards while minimizing loss of coal. The Approach: Development of a computer program that will compute many possible mine layouts by changing the mine plan until the arrangement giving minimal hazards with optimum extraction is found. How It Works: The Hazard Evasion Program for Mine Planning, developed by the Bureau's Denver (Colo.) Mining Research Center, tests hundreds of possible solutions to a mining layout, and by sorting out the 10 best (based on the criteria of maximum safety for workers with minimum abandoned coal), limits the number of choices that need to be considered and appraised for applicability to a given mine scheme. The program is applicable for room and pillar or longwall mining, for oil and gas well hazards, and for other hazards that can be described mathematically such as channel sands, potential bad roof areas, faulting, voids, or water pockets.

Jan 1, 1974

By W. W. Weller

This report provides low-temperature heat-capacity data and entropies at 298.15° K. for magnesium metavanadate (MgV206) and magnesium pyrovanadate (Mg2V207). The work completes low-temperature measurements planned for alkaline-earth vanadates; an earlier report dealt with calcium vanadates.4 No similar data for these compounds have been published previously. Free energy of formation values at 298.15° K. were derived by combination of the present entropy values with heat of formation data. MATERIALS The materials used in the measurements were portions of the samples described in a previous Bureau of Mines publication by King, Koehler and Adami.5 Methods of preparation, chemical analyses, and X-ray examinations are covered in this paper. The indicated purity of the samples was 99.9 pct.

Jan 1, 1962

By N. S. Dalal, V. Castranova, K. Van Dyke, V. Vallyathan

"IntroductionInhalation of crystalline silica is often associated with the development of pulmonary disease (Ziskind et al., 1976). Recently, it has been proposed that freshly sheared silica .may have surface properties that make it more reactive with lung tissue than aged silica, and that this unique reactivity ·of freshly crushed silica enhances its pathogenicity. A recent study in our laboratory strongly supports this theory (Vallyathan, et al., 1988a; 1988b). We found that grinding of silica cleaves bonds in a silica tetrahedral lattice generating reactive free radicals sites on the surface of the silica particles. The presence of surface radicals on freshly ground silica was monitored by electron spin resonance (ESR) spectroscopy. The ESR signal generated from fresh silica in air is characteristic of Si-0 and Si radicals. Evidence, i.e., the ESR signal after the addition of a spin trap (DMPO) and its sensitivity to ethanol, indicates that these silicon-based surface radicals can react with water to form hydroxyl radicals (OH). Results also indicate that these surface radicals make fresh silica more cytotoxic than aged silica; i.e., fresh silica causes more membrane damage as evidenced by hemolysis and lipid peroxidation. Therefore, the presence of reactive sites on the surface of freshly cleaved silica may play a significant role in its pathogenicity.If surface· free radicals are related to cytotoxicity, then screening dusts for the existence of such radicals may predict their relative pathogenicity. Since an ESR spectrometer is not available to many laboratories, the objective of this study was to develop a quick and simple technique to monitor the existence of reactive surface sites on dust. The technique chosen was the measurement of chemiluminescence using a liquid scintillation counter; i.e., an instrument which·would be accessible to most investigators."

Jan 1, 1989

By Edward F. Courtney

Loss of life, loss of sight, crippling injuries, and property damage nearly always result from accidents involving explosives. The severity of such accidents has prompted lawmaking bodies to pass laws concerning the transportation, handling, and use of explosives; manufacturers of explosives publish manuals 'describing explosives and practical methods of handling then; and mining companies and others who use large quantities of explosives publish rules based on actual experience for the guidance of their employees. Careless storage of explosives by thoughtless or incompetent persons, particularly if they are left where children or saboteurs have access 'to them, has led to many serious accidents. Many contractors and mining operators who use explosives are extremely careless about storing them. It is the purpose of this paper to discuss the explosive-handling practices of a large western mining company, which are considered better than most.

Jan 1, 1946

By Oliver Bowles

Slate possesses many admirable qualities, not only as a roofing material, but for blackboards, electrical switch boards, and for various structural uses such as stair trends, floor tile, baseboards, and sanitary enclosures. The American slate industry was established manor years ago, and has made remarkable progress, particularly during the past five years. One of the chief drawbacks to more rapid expansion is the high percentage of waste which reaches 75 to 94 per cent of gross production. Much of this waste is duo to rock imperfections over which man has no control, but a careful study of tae industry by the Bureau of Mines over a period of years indicates that an undesirably large percentage of the marketable slate is wasted in the processes of quarrying and manufacture. The initial step in quarrying slate is to separate from the solid ledge masses of a size that ray be conveniently removed from the quarry. This first step entails a greater waste of material than any subsequent process, and, therefore, invites the most earnest effort toward waste reduction. Attention has consequently been directed toward possible improvements in methods of making primary cuts in the quarry floor. A study of European practice with the wire saw, together with theoretical consideration of its advantages, convinced the writer that it possessed sufficient merit to justify its use as a primary slate cutter in American quarries. No practical conclusion in this matter could be reached except by experiment. Therefore, the desirability of obtaining equipment and trying it out under actual conditions of operation was urged upon operators. While no doubt the equipment could be readily manufactured in America, it had already been developed to the point of practical use in Europe; therefore the writer urged the desirability of purchasing one completely equipped wire saw in Europe, and determining through tests whether it gave sufficient promise of success to warrant its manufacture in America.

Jan 1, 1927

By Carlton E. Brown

In 1935 , Brown and Yant / described a microprojector ( microscopic arrangement for projecting images on a screen ) for use in counting and measuring the size of dust particles in Owens - jet dust - counter and simila dry samples of dust collected from the air . In 1938 Brown and others , described a modification of this microprojector that could be used also in counting dust in impinger samples . Microprojectors of this second type have been set up by many mining companies and others and have been made commercially available . Hamly and Pullen5/ described a modification of this microprojector for use in making rapid comparative estimates on konimeter samples and other determinations . This report contains information on still another modification named the "midget microprojector " because of its small size .

Sep 1, 1944

By M. J. Ankeny, J. J. Forbes

Several sets of questions and answers on the fundamentals of first aid to the injured, based on the Manual of First-Aid Instruction of the United States Bureau of Mines, are now in use in various parts of the United States. Persons experienced in first-aid instruction believe that a standardized set of questions and answers will assist materially in preparing men for examin- ations conducted by the Bureau for first-aid certificates. Inquiries as to whether a set of standardized questions and answers is available have been made frequently by those training men for the Bureau of Mines examination for certificates. It is believed that the following list of 171 questions and answers com- piled directly from the manual will be useful to company officials and em- ployees who are engaged in cooperative first-aid training to qualify for Bureau of Mines certificates. The list may also be used by field men of the Bureau in training instructors preparatory to a cooperative training campaign and in examining classes or individuals for first-aid certificates. The page references in parentheses refer to pages in the Manual of First-Aid Instruction.

Oct 1, 1935

By L. C. George

The Bureau of Mines measured the vapor pressures of selected mixtures in the binary systems CdCl2 ?SnCl2, CdCl2 -ZnC12, PbCl2 ?SnCl2, and PbCl2 -ZnCl2 by the static pressure method. These data were evaluated by the second-law (sigma-plot) method. Equations expressing the vapor pressures and the heats and free energies of vaporization as functions of temperature are given.

Jan 1, 1969

Provide an economic alternative to drill-blast excavation with the same ability to excavate openings of varied orientation, shape, and size. Approach Develop an efficient, adaptable, mechanical excavation machine that produces unconfined tensile failure in rock. How It Works A drill-split fragmentation machine that combines a drill and a unique splitter has been developed. The drill and splitter are mounted on a carriage that positions the splitter in a hole immediately after it is made by the drill. The splitter creates force loads that cause the rock to fragment, and the process is repeated for excavation. The unique splitter applies both radial and axial loads to the rock mass, which produces an excavation action comparable to pulling a plug. This excavation action distinguishes the radial-axial splitter from typical demolition splitters, which require a free surface parallel to the axis of the splitter toward which to break rock.

Jan 1, 1989

"While control of dust-related diseases, the objective of the Generic Mineral Technology Center for Respirable Dust, is of prime importance from the human standpoint it is also essential to the economic well-being of the mining industry (FIGURE 23). Although significant progress has been made, the problem continues to be a major concern to the mining community. An increasing global demand for coal and other minerals means that production and the number of miners employed is on the rise. Therefore, the importance of this research to the mining industry cannot be overemphasized.The five areas of dust research are 1) control of dust generation, 2) dilution, dispersion and collection of dust in mine airways, 3) characterization of dust particles, 4) interaction of dust and lungs, 5) relationship of mine environment, geology, and seam characteristics to dust generation and mobility. Some experimental projects where the research is conducted almost exclusively in the laboratory may still rely on industry for imput. No industrial resources are necessary to the research of the non-experimental projects, for example computer modeling .The remaining research is classified as experimental and these projects do require interaction with industry in varying degrees. Periodic trips to mining sites in Western Pennsylvania, Southern Ohio, and West Virginia are necessary to record measurements or collect samples. Or companies may provide needed samples or equipment to the university for use in the laboratory. On several projects interaction is limited to advice or information supplied to the researcher by industry personnel."

Aug 31, 1989

By T. J. Ballard

The Track Rock corundum mine was among the numerous corundum deposits investigated during the war by the Bureau of Mines in an effort to develop domestic reserves of that critical mineral. In the investigation of this property 562 feet of trenches were excavated and a l25-foot adit was reopened for the purpose of locating veins to of corundum which had been previously reported to occur in that locality. Only very minor amounts of corundum were disclosed in both the surface workings and the adit. The project was begun in May 1943 and completed in November 1943.

Jan 1, 1948

By Ralph B. Adair

The Bureau of Mines conducted laboratory and small-scale, continuous tests of weathered mica-pegmatite ores from Randolph County, Ala., to determine the feasibility of recovering commercial-grade mica concentrates by flotation. Two flotation methods were used in continuous tests for recovery of mica. One method utilized acid-cationic flotation for the recovery of coarse mica and alkaline-anionic-cationic flotation for recovering fine mica. This method yielded mica concentrates containing 98.6 percent mica with a recovery of 85.9 percent. The other method was based on the Bureau-developed alkaline-anionic-cationic method, and yielded concentrates containing 97.5 percent mica with a recovery of over 90 percent. In both methods, preconcentration of the ground ore on a Humphreys spiral was employed to reject over half of the feed in a product virtually free of mica.

Jan 1, 1968

By R. M. Winslow

"The phosphorus content of an iron ore is a determining factor as regards the value of the ore and also its metallurgical treatment. If some method of treatment, such as concentration, leaching, etc., could be used and the phosphorus con- tent of the ore reduced, it would be an important advancement in the iron mining industry towards the utilization of high phosphorus ores. Large bodies of material toe high in phosphorus to be marketable under present conditions would be made available, and a great deal of ore from the Cuyuna Range and other places, which is relatively high in phosphorus but otherwise suitable for making spiegel, could be reduced in phosphorus content sufficiently to permit its use in furnaces producing speigel.The form in which phosphorus occurs in iron ore is a much disputed question and it probably varies with the type and location of the ore. The statement has been made that ore piles on long exposure to the atmosphere often decrease in their phosphorus content. (Emmons, S.F. - Ore deposits, 1913, p. 652; Leith, C.K., Mesabi iron bearing district, U.S.G.S. Monograph 43, 1903, p. 275) There is described below experiments on the leaching of iron ores high in phosphorus, to determine whether it was economically possible to reduce the phosphorus content appreciably by leaching. As the research had a practical as well as a theoretical application, only low concentration of acids and alkalies were used.A number of variables were tried, among these being: (1) The solvent used, (2) strength of the solvent, (3) volume of solution used, (4) time ore was agitated (5) type of ore, and (6) screen size of the ore. The amount of ore taken was kept constant."

Jul 1, 1921

By Thomas Varley

"Concentration, ore-dressing, or the dressing of minerals are common terms used in metallurgy and indicate processes of separating valuable minerals from worthless gangue. It is understood, of course, that the products from such processes, being separated from the various minerals and gangue, are ready for commercial sale or for further treatment by smelters and refineries.Gravity concentration takes advantage of the difference in specific gravity of the various constituent minerals and gangue of waste material in the ore. The two most common forms of concentration by this means are jigging and table concentration. Jigs usually are used in the separation of relatively coarse material and the tables for the finer material, the line of division in general being about 20 mesh.There are mar factors to be considered .before a decision can be made as to what method would be best adapted to the successful treatment of an ore and only by careful experiments can this be determined. Among the important factors to be considered are. The nature of the minerals present, their physical and chemical relations to the gangue material, and the gangue material itself. Perhaps the most important is the number of minerals present and their relation to each other.Metals exist in ores in three principal forms -- sulphides, oxides or carbonates, and native. Concentration by gravity methods is in general best suited to sulphide ores, although in some places considerable success has, been obtained in the concentration of oxide ores by gravity methods."

Apr 1, 1920

By Michael R. Yenchek

The U.S. Bureau of Mines investigated the operational characteristics of spliced portable power cables. This research had a dual purpose: (1) to determine the thermal and mechanical performance of repaired trailing cables and compare them with undamaged cables and (2) to gauge the impact of long-term, localized heating on the insulating and jacketing materials contained in cable splice kits accepted or approved by the Mine Safety and Health Administration. The ranges of splice joint resistance and tensile breaking strength were determined from laboratory measurements. The choice of crimping tools affected the strength of the splice under tension. Thermal profiles of energized spliced cables were constructed, which showed that spliced conductor joints operated 5 to 20°C hotter than the intact cable at rated currents. Accelerated life tests of thermally aged samples of splice kit insulation and jacket materials confirmed a deficiency in the thermal rating of the insulating tape. The recommendations in this report may be utilized to revise splice kit design, splice kit approval criteria, and trailing cable loading guidelines. Characterizing the thermal operating limits of spliced trailing cables may help to minimize the associated risks from explosions, fires, personnel burns, and shock.

Jan 1, 2010

Develop a technology for producing high-quality hake graphite from the steelmaking waste known as kish. Approach Treat the waste kish as an ore and apply mineral processing techniques of physical beneficiation and chemical purification to produce a range of graphite products com¬petitive with the natural mineral. Background Graphite is a naturally occurring form of carbon with a unique combination of properties that make it indispensable in a very wide range of industrial and consumer applications. It has high electrical and thermal conductivity and remains stable to extremely high temperatures It has a low coefficient of friction and is nearly impervious to corrosion. The steel industry is dependent on graphite in clay-, magnesia-, and alumina-bonded refractories for crucibles, bricks, facings, and coatings. Electrical uses include graphite brushes in motors and generators, and electrodes in batteries. The transportation industry needs graphite for clutch and brake linings, and all industries depend on graphite in seals, gaskets, lubricants, and coatings. The consumer sees graphite in composite plastics and in the common pencil. As with all natural minerals, the availability of graphite is diminishing and costs are rising as quality decreases.

Jan 1, 1993

By Albert J. Forney

A process for the manufacture of high-Btu gas from coal has been developed by the Bureau of Mines. The process consists of fluid-bed gasification of the coal, followed by the gas treatment steps of gas purification and methanation. Advantages of the system are that caking coals can be used directly, and more than half of the ultimate methane is made in the gasifier.

Jan 1, 1970