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By N. E. Hanna

Originally developed for use in coal mines where on-shift blasting with explosives was prohibited, compressed-air blasting has been used for the past 15 years as a substitute for fixed explosives. With the current commercially available compressed-air systems -Airdox and Armstrong -coal is dislodged by a high-pressure discharge of air from a pressurized shell placed in the coal borehole. In the original systems stationary compressors were mounted on the surface or in the underground ventilated areas. These proved so successful that a mobile compressor unit was developed for use at the working face. Because of the possibility that such a unit might operate in a gassy atmosphere, the Bureau of Mines has investigated the hazards associated with operation under conditions where firedamp could accumulate in explosive concentrations. ACKNOWLEDGMENTS Grateful acknowledgment is made of cooperation of C. E. Carter, H. R. Hiller, R. E. Kennedy, H. Kohn, H. D. Metzinger, J. Mahoney, J. Nickovich, G. So Scott and I. Spolan in the experimental work.

Jan 1, 1956

By G. A. Smyres

The Bureau of Mines investigated a HCI-02 leaching procedure to recover Cu, Ni, and Co from a low-grade bulk sulfide flotation concentrate prepared from the Duluth gabbro complex. Since the Duluth gabbro complex is the largest known and unexploited Ni resource in the United States, the development of options for extracting the metal values from the flotation concentrate of this domestic resource is necessary. Conditions were determined for producing a pregnant solution low in Fe to facilitate recovery of the metal values. Leaching experiments were conducted at 15 pct solids, 1000 to 1200 C, 0.2 to 0.3 g HCI per gram concentrate in a 50-gal reactor pressurized to 50 pSig with 02. Base metal extractions from the concentrate were, in percent, 90 to 92 Cu, 99 Ni, 97 to 99 Co, and 0.1 .Fe. Precious metals extractions were erratic and unpredictable; at best their extractions were, in percent, 55 Au, 90 Ag, 40 Pt, and 45 Pd. The reaction time at 1200 C was 0.5 h. The use of compressed air instead of 02 as the oxidant was also investigated. Solvent extraction using LIX 622 was used to remove Cu from the pregnant solution. Cementation on Cu was tested for precious metals recovery, while sulfide precipitation was used to produce a Ni-Co product. A conceptual flowsheet for treating the Duluth gabbro concentrate is proposed.

Jan 1, 1985

By J. M. Mutmansky, C. Lee

"This paper outlines some of the work associated with a research study into the relationship between the characteristics of coal mine dust and the incidence of coal workers' pneumoconiosis (CWP). The project involves study of the chemical, mineralogical, and morphological characteristics of the dust. Early stages of the study have dealt primarily with the size analysis and elemental composition of airborne dust in continuous miner sections. This paper outlines the procedures and findings of the elemental analysis portion of the study.Most of the previous elemental analyses of coal were made available in the quest for information on the combustibility of coal dust or on causal agents and prevalence of CWP. However, no extensive studies have been performed to date, primarily due to the limitations of the analytical methods. A review of the analytical methods for elemental characterization of coal and coal dust particles is presented. TI1e comparisons are made based on the sample mass required, the sample preparation required, the destructivity of the test, and the capability of providing an easy multi-element analysis. The reasons for selecting the proton-induced x-ray emission spectroscopy (PIXE) method are outlined.The PIXE method was applied to both the airborne coal mine dust and channel samples collected from seven continuous miner sections in six different mines. Channel samples of the coal, roof and floor were collected and analyzed. Airborne dust sampling was performed using multi-stage cascade impactors and permissible 2.0 I/min pumps. Sampler locations were fixed in the sections with respect to the continuous miner and roof bolter or with respect to the intake and return airways. Sampling times varied from 45 minutes to 6 hours, depending on the dust concentration.The statistical analysis of the resulting elemental data is presented. Of particular importance are the analyses of the variation of elemental composition with size and the variation in elemental composition over the working section. One interesting finding is outlined showing the multivariate statistical analysis of the trace elements and its implications in the identification of the dust sources. The paper concludes with an analysis of the ramifications of the elemental data to related medical studies."

Mar 1, 1989

By John C. Machisak

The thirty-fifth consecutive National Safety Competition sponsored and conducted annually by the Federal Bureau of Mines, Department of the Interior, closed with several noteworthy accomplishments to its credit. Some of them are: 1. A record low injury-frequency rate of 18.293 disabling work injuries per million man-hours equal to that established in 1957. 2. The third lowest injury-severity rate (4,335). 3. The second highest number of mines and quarries participating (672) 4. A record number of participants finishing the competitive year without a disabling work injury. 5. All recipients of Sentinels of Safety trophies free of disabling work injuries for the first time since 1952.

Jan 1, 1961

By Joseph J. Wallace

1. The investigation shows that nine coal beds have been mined in Harlan County, of which the Harlan and Upper Elkhorn No, 3 are the most important from the standpoint of present production. Of less importance are the Hindman, Flag, Haddix, Wax, Fire Clay, Armburgy, and Upper Elkhorn No. 2. The Harlan, Upper Elkhorn No. 3, and Upper Elkhorn No. 2 beds contain the largest remaining known reserves. 2. Known measured and indicated reserves in all beds, based on a minimum thickness of 14 inches and 1,800 tons per acre-foot of coal in place, are estimated at 2,138 million short tons as of January I, 1932. Of this total, 1,956 million short tons is in beds 28 inches and more thick. Areas in each bed were omitted from the estimate because available data relative to the bed characteristics are too meager for making an estimate that conforms with the definitions of measured and indicated coal adopted for this study, Should future drilling or development prove reserves in these areas, such reserves should be added to the total estimated reserves.

Jan 1, 1954

By F. D. Stevenson

Thermodynamic properties of metal halides and, in particular, vapor pressures have become of great importance in recent years owing to increased application of chemical processing to extraction of metals from their ores. Vapor pressure data serve not only as a valuable source of latent heat of vaporization and fusion values but also differences in metal-halide vapor pressures often provide the basis for their separation by conventional mass transfer operations. This literature search was made to provide a ready reference to experimental vapor-pressure data of metal halides and oxyhalides. Results are reported in two main sections: (1) A tabulation of vapor- pressure references for each of the metal halides (listed by metal) for which actual experimental data are reported (table 1), and (2) a bibliography of the citations. Metal halides and oxyhalides are listed by chemical formula and chemical name, based on the stock4 system. To facilitate location of the references, a listing of the journal titles and their abbreviations follows the bibliography.

Jan 1, 1963

By D. C. Crowell, A. G. Loomis

Both Dimensional and Inspectional Analysis are developed from fundamental concepts , and dimensionless groups are derived which represent the viscous , capillary , and gravitational forces existing in two - phase , incompressible flow in petroleum reservoirs . It is shown how properly scaled models may be devised by means of the foregoing groups . Laboratory measurements with such models faithfully duplicate the behavior of the reservoir on a miniature dimensional and compressed time scale , and when all the pertinent variables are evaluated , the model is a most effective tool for the study of complex fluid displacements in the reservoir . Applying the Principle of Similitude , it is shown how dimensionally scaled models are applied to various types of reservoir displacements : ( 1 ) Oil displaced by water , ( 2 ) gas displaced by water , and ( 3 ) miscible displacement . The special case of water displacing gas by imbibition is analyzed , and it is shown that the dimensionally scaled model must be fabricated of sandstone rather than unconsolidated sand , which is generally used in such models . This report is intended to be a review and summary of the application of Dimensional Analysis to reservoir displacement problems for those who are beginning the study of this useful and interesting method .

Jan 1, 1964

By L. B. Pankratz

Enthalpies above 298° K were determined for AgCl to 1,400° K and for AgBr to 1,200° K by copper-block calorimetry. Before melting, both compounds showed an anomalous increase in enthalpy, an effect associated with lattice defect formation. Melting points and heats of fusion were determined to be AgCl, 730° K and 2,945 cal/mole; AgBr, 700° K and 2,030 cal/mole. The heat capacity of both melted substances decreased with increasing temperature over the entire liquid ranges investigated. Enthalpies above 298° K were tabulated at even temperatures along with derived entropy increments and heat capacity values. The results were combined with the known heats of formation and entropies at 29.8.15° K to obtain values of the heats and free energies of formation over the range 298.15° to 1,400° K for AgC1 and 298.15° to 1,200° K for AgBr.

Jan 1, 1970

By Frederick W. Horton

The lack of comparable and accurate statistics of coal-mine accidents in the United States as a whole led the Bureau of Mines in 1911 to undertake the collection of such data. The importance of such statistics as a basis for remedial legislation can not be overestimated, moreover they serve to indicate the results of the efforts made by the Federal Government, State mining departments, and mine operators throughout the country to lessen the hazard of coal mining. The mining departments of the leading foreign coal-producing countries have long taken cognizance of the importance of such statistics. In Great Britain, official statistics of coal-mine accidents have been collected and published since 1851, in France since 1853, in Austria since 1875, in Germany since 1852, and in Belgium since 1831. The United States not only leads these countries in the production of coal but the output of its coal mines is greater than those of Great Britain, France, Belgium, Austria, India, Japan, and New South Wales combined. Accordingly, it is proper that there should be some official record of the accidents in this, the greatest mining industry not only in the United States but in the world. It is especially appropriate that this work should have been undertaken by the Bureau of Mines, as, through its investigations of mine accidents in the field, it is constantly in close touch with coalmining conditions throughout the country. Its engineers are not only able to obtain first-hand information as to a great many accidents, but, through their special training and experience, are able to appreciate the significance of the figures reported by the coal-mine operators, thus aiding an intelligent and uniform classification 01 the accidents for the country as a whole. Further, the State mining dnpartments and State mine inspectors of every State in the country having a system of coal-mine inspection are cooperating with the bureau by sending it monthly reports of accidents in the coal mines of their respective States. The receipt of such reports places the bureau in a most advantageous position to publish promptly statistics of these accidents. Although a few years ago accurate statistics of c~al-mine accidents in the United States as a whole were entirely lacking this bureau was able to pubjiish the 1912 statistics within three n:onths after the close of the year and long before corresponding statistics had been issued by the mining departments of the leading foreign coal-producing countries. The cooperative agreement with the State coal-mine inspectors has not only made possible the prompt publication of the statistics, but it has also enabled the bureau to classify the fatalities by months and according to cause, showing the months in which the greatest and the least number of men were killed and from what causessomething that has never before been accomplished for this country.

Jan 1, 1913

By H. E. Powell

Basic data were recorded on the decompositions that take place during thermal decomposition of siderite (FeC03). Both the naturally occurring and a synthetically prepared mineral were studied by differential thermal, thermo-gravimetric, X-ray-diffraction, and chemical (including gas) analyses. Thermal decomposition was studied in the media of dry air, moist air, dry carbon dioxide, dry helium, and dry carbon monoxide and at atmospheric and at reduced pressures. Results showed the thermal decomposition of FeC03 to be an extremely complex process, dependent on environmental factors and side reactions that cannot now be completely controlled. Therefore, full understanding of the reaction involved must depend on additional research with advanced evaluation techniques.

Jan 1, 1965

By G. L. Oldright

In the first Report of Investigations of the present series?(No. 4562) the usual course of progress ill reducing the minerals of low-grade ores to their valuable metallic components had been noted as advancing along two lines to concentrate a usually diminishing percentage of these minerals to a smaller bulk of richer product, and then to smelt the smaller bulk more cheaply per pound of metal produced. Fundamental properties of lead compounds made it difficult to treat much richer lead products than are treated at present in several steps of conventional lead smelting, unless ?marked modifications were made. No limits to the richness of the feed itself' were set by the ore (Scotch) hearth; on the contrary, the richer the feed, the better the results given by the hearth. The natural field of operation of the hearth, as determined by the ores available, was seen to lie in the Central United States, with their lead concentrates containing negligible quantities of precious metals and. with few ores of such metals available for use as fluxes. It was noted) however, that even in its chosen field, the Scotch hearth, or "ore" hearths developed from them, was not always used; the usual smelting practice was followed, at times, of sintering followed by blast-furnace smelting for even rich ores.

Jan 1, 1949

By Thomas C. Denton

ALL of the 45 political divisions of Africa were accessible to non-Communist world industry and commerce throughout 1964, although in some of them revolt and political attitudes presented problems. The position of the continent as a whole for mineral and mineral fuel resources, production, and oversea exports continued to improve. At yearend, significant quantities of a greater number of mineral commodities vital to industry and agriculture were being produced than in any other continent. This statement excludes Communist areas on other continents but might well hold true even if such areas were included. Deriving from its exceptionally diversified production, Africa furnished overseas industrialized countries as a w ole a greater variety of key mineral commodities than any other area. In addition, the value of mineral imports from Africa into the United Kingdom and continental non-Communist Europe probably exceeded the value of such imports from any other area if gold is included and mineral fuels excluded.

Jan 1, 1966

These proceedings consist of papers presented at Bureau of Mines Technology Transfer Seminars in December 1983 for the purpose of disseminating recent advances in mining technology in the area of mine ground control. The Bureau of Mines conducts several of these seminars each year in order to bring the latest results of Bureau research to the attention of the mining industry as quickly as possible.

Jan 1, 1984

By Oliver Bowles

In 1943 the Bureau of Mines began a review of trends in consumption and prices of the more important nonmetallic minerals. The first report covering building materials4/ appeared in December of that year. The present paper, which deals with chemical raw materials and fertilizers, is the second of the series. The 34 years from 1910 to 1943, for which statistics are presented herein, comprise periods of uneventful peace, unparalleled prosperity, industrial depression almost to the point of stagnation, and two wars of world proportions.

Jan 1, 1945

By R. E. Heithecker

Zwolle oil field of Sabine Parish, La., is different from most oil producing areas of the State in that the oil is obtained from marl and chalk-rock formations. The thickness of the reservoir rocks averages 500 feet; but production is not continuous throughout this thickness, as the oil apparently is localized in vertical and nearly vertical solution cavities and channelways or in porous zones of limited horizontal extent. The nature of the oil accumulation has caused two outstanding peculiarities of the field: (1) About 60 percent of the tests drilled were dry holes and (2) there were many instances of well interference. Commercial production was discovered in November 1928, after 17 years of prospecting in and around the present limits of the area now developed which has a length of about 22 miles and a maximum width of 4 miles. The field had produced 10,266,896 barrels of oil to January 1, 1934. The oil ranges in gravity from 400 to 420 A.P.I. Although the field is divided into several districts which are more or less clearly defined and separated by unproved territory the term Zwolle field", as used in this report, includes the entire area from Blue Lake on the west side, through Zwolle proper, and eastward, including the Many or Eastern extension.

Jan 1, 1934

By Frederick C. Trutt

A guide to the development and utilization of an interactive mine-power-system fault program (Z-bus by algorithm) is presented. Theoretical foundations, as well as implementation considerations are discussed with respect to the mine-power system. Alternative Kron reduction techniques are presented along with a triangular-storage method for storage conservation. Program capabilities include the analysis of balanced and unbalanced (line-to-line, line-to-ground, and line-to-line-to-ground) fault situations using symmetrical component theory. To account for phase shifting in delta-wye transformers and zero-sequence network constructions, transformer and load configurations are specified by the user. The positive-and zero-sequence connections needed for network conformity are automatically constructed with the required impedances.

Jan 1, 1979

By R. A. Cattell

Continuing progress in a petroleum and natural gas research program of world-wide significance makes it difficult to pinpoint accomplishments within definite time limits, and it is helpful to look back as well as forward in attempting to introduce and summarize the petroleum work of the Bureau of Mines in the fiscal year 1953. The 1952 report2 / indicated progress in a long-range program applicable in large part to both defense and peacetime requirements. The present report indicates a continuation of that program, modified partly by new demands and interests of government and industry, and is highlighted by a number of significant contributions to the knowledge of petroleum and natural gas and their production and utilization. The intent of the program was clearly epitomized in a statement made near the end of the fiscal year at a general conference of Bureau of Mines personnel where the record was critically reviewed:

Jan 1, 1955

By Donald J. Keefe

The Remote Working Level Monitor (RWLM) is an instrument used to remotely monitor the Rn-daughter concentrations and the Working Level (WL). It is an ac powered, microprocessor based instrument which multiplexes two independent detector units to a single central processor unit (CPU). The CPU controls the actuation of the detector units and processes and outputs the data received from these remote detector units. The remote detector units are fully automated and require no manual operation once they are set up. They detect and separate the alpha emitters of RaA and RaC' as well as detecting the beta emitters of RaB and RaC. The resultant pulses from these detected radioisotope; are transmitted to the CPU for processing. The programmed microprocessor performs the mathematical manipulations necessary to output accurate Rn-daughter concentrations and the WL. A special subroutine within the program enables the RWLM to run and output a calibration procedure on command. The data resulting from this request can then be processed in a separate program on most computers capable of BASIC programming. The calibration program results in the derivation of coefficients and beta efficiencies which provides calibrated coefficients and beta efficiencies.

Jan 1, 1977

By W. J. Fene

A comprehensive study of all bituminous coal-mine fatalities occurring in Pennsyl¬ vania during the 5-year period, 1926-1930, was made to try to determine the factors that in¬ fluence accidents which cause these fatalities. During this study some two thousand reports of fatalities were reviewed, and pertinent information as to causes and influencing factors were tabulated therefrom. These tabulations are discussed in detail, and in some instances recommendations are made with a view to reducing the hazards in certain classes of these accidents.

Sep 1, 1931

By D. Harrington, W. J. Fene, H. B. Humphrey

In the fiscal years 1946 and 1947 the number of mine explosions decreased compared with the preceding years. However, the loss of life was so serious during the fiscal year 1947 the period when the Government administered bi- tuminous-coal and lignite mines that from April to June 1947 extraordinary measures were taken in mines then under Government possession to obtain com- pliance with provisions concerning rock dusting, ventilation, and blasting that had not been followed. The great loss of life in explosions during the fiscal year 1947 as compared with 1944, 1945, and 1946 is not easy to explain, but the necessity for maintaining adequate protection has been definitely demonstrated. Management, workers, and inspection agencies alike must keep the mines reasonably safe against explosions or allow them to lapse into a condition where chance is the principal protection against disaster. The at- tention given to protecting coal mines and the men employed in them against mine fires, following the disastrous fires in 1944 and 1945, has at least tem- porarily controlled this hazard loss of life from coal-mine fires was re- duced to 1 fatality in 1947. The number of fires was also less, and progress has been made in reducing the heavy losses in both life and property from un- derground coal-mine fires that occurred in the two years mentioned. Fatalities from mine explosions during the past 6 fiscal years, July 1942 to June 1947, totaled 674, and there were 149 explosions; during the preceding 6 years there were 655 fatalities in 132 explosions. The 6 fiscal years 1942- 47 cover the active period of Federal coal-mine inspection. During the fiscal year 1947, there were 154 fatalities from explosions compared with 58 during the fiscal year 1946, 64 in 1945, 94 in 1944, 152 in 1943, and 152 in 1942.

May 1, 1948