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By Ann G. Kim

The Bureau of Mines estimated the methane content of a coal, which depends primarily upon rank and pressure, from the adsorption equation V kpn, where k and n are constants related to rank. By incorporating corrections for moisture, ash, and temperature, and estimating pressure and temperature as a function of depth, the methane content of coal in place can be estimated from the following equation: [ ] Values calculated with this equation generally are in reasonable agreement with direct determinations. By assuming a standard moisture and ash content, and using the hydrostatic head to estimate pressure, a graph of rank and depth versus gas content was constructed. Although estimated values were consistently high for several high-volatile bituminous coals from an area where the pressure is known to be less than hydrostatic, the estimated methane content for most coals shows reasonable agreement with values determined by the direct method.

Jan 1, 1977

By E. H. Illsley

This bibliography is the first report of a Bureau of Mines research project on thermoelectric materials. Interest in such research has increased because of recent success in the design of commercial products, including generators and refrigerators, using the principles of thermoelectricity. This success made possible by the discovery of semiconductors that have much higher [effincies] than the metals and alloys formerly studied. Thermoelectricity is a term that includes a large number of phenomena relating heat to electrical energy. However, the moat important applications arise from two effects discovered by Seebeck in 1822 and by Peltier in 1834. When pieces of two unlike materials are joined at their two ends to form a continuous circuit, both of these effects may be observed. If the two junctions are maintained at different temperatures, an electromotive force known as the Seebeck voltage is generated. If, on the other hand, a current is made to flow through the circuit, the junctions of the materials will be found to differ in temperature. This phenomenon is called the Peltier effect.

Jan 1, 1959

By Ludwig Schmidt

The petroleum industry has recently shown sucks great interest in the evaporation of crude oil and of gasoline, and in the prevention of evaporation losses that almost daily there is being developed and placed on the market equipment designed especially to reduce these losses. Among the recent developments is a new type of tank roof known as the "floating roof," which practically eliminates the vapor space over the surface of the oil, thus removing one of the chief causes of evaporation. There are at the present writing at least two types of floating roofs which, while similar in fundamental principle, differ mainly in the method of making contact with the inside shell of the tank. One type of floating roof is known as a floating tank deck, and has on its circumference flexible metal baskets containing gravel that .rest against the inside shell of the tank. In the other type of floating roof contact with the tank shell is made by the use of movable buffers or shoes. These are attached to the outer ring of the roof and are pressed against the tank shell by means of springs.

Jan 1, 1923

By Robert Hall

The Lynch Creek beryllium-tungsten prospect was investigated as part of the domestic beryllium resource studies by the Bureau of Mines. This prospect is in the Birch Creek mining district, Lander County, Nev., 9 airline miles south of Austin. A tungsten mine was operated intermittently from 1952 to 1957. Beryl was identified in the pegmatite dikes in 1960, and the lode claims were relocated. No beryl has been produced. Rocks in the area are Paleozoic sediments2 cut by pegmatite and aplite dikes and quartz stringers. Beryl occurs in random pockets, as disseminations throughout the dikes, and in occasional pockets in the quartz stringers.

Jan 1, 1962

By J. Tomlinson

Shuttle car trailing cable splices were tested for resistance to failure upon being subjected to repeated bending, abrasion, and tensile shocks using a new testing method that closely simulates shuttle car induced stress. The results show that under normal stresses, splices can be made to withstand the equivalent of three months of operational use. Restoring the tensile strength to the conductors is found to be as critical as restoring flexibility. Splices in which the conductors are of slightly unequal length did not present as serious a workmanship problem as previously thought since test results show that the conductors tend to equalize when longer cables, in contrast to short cables employed in previous testing methods, were used. Dynamic recordings of cable tensile stresses are presented for a shuttle car and the new simulated testing method. Two simple but effective methods for removing insulation using a knife and a pair of pliers are described. None of the designs tested for a sacrificial splice covering were satisfactory.

Jan 1, 1979

By D. Harrington

This circular presents part I of a series of papers of a review of the literature on air conditioning in mines, with particular reference to the health, safety, and efficiency of miners. It deals with the physiological aspects of exposure to air contaminated by organic matter, noxious and toxic gases, and dusts that emanate from various sources in underground workings; part II will discuss the relation of abnormal mine temperatures and humidities to the health and efficiency of minors; and part III will describe theoretical and practical methods of air conditioning mines to correct or alleviate the conditions mentioned and will discuss the results attained by some of the systems now in use in various parts or the world.

Jan 1, 1938

By Robert L. Lappi

This report covers the final phase of a project demonstrating the economic efficiency of cross-ridge mountaintop coal mining. A demonstration mine was established at Big Wheel Gap in northeastern Tennessee. Not only was cross-ridge mining feasible for the selected site, but parallel cut methods could not be used due to a deficit in available spoil storage. Cross-ridge mining permitted coal extraction at a cost almost identical with costs simulated by computer projections using mathematical optimization techniques. No unexpected environmental problems were encountered. Volume I is accompanied by Volume II which describes the MATHMINE Mine Simulation System, software used to support the mining demonstration.

Jan 1, 1984

By William C. Larson

A study was conducted by the Bureau of Mines to provide quarry operators with information regarding (1) the effects of jointing and bedding on rock fragmentation when bench blasting in two small-scale (2.5-ft) limestone benches, and (2) the successful use of inexpensive equipment and field techniques to determine the orientation and spacing of joints and bedding separations within the quarry. Using inexpensive equipment, such as a pocket transit and steel and paper tapes, joint and bedding separations were mapped and their frequencies measured. Results from two small-scale bench blasts in the Stewartville member of the Galena limestone formation showed that when the row of vertical blast-holes was oblique to the vertical joint orientations, the backface expression was outlined by two relatively large triangular protrusions (joint surfaces). In this blast, part of the rock burden was unbroken. When the line of vertical blastholes paralleled a predominant joint set, all of the rock burden was broken and displaced. The thickness of fragments that had been displaced by a blast correlated with the observed bedding thickness in the bench.

Jan 1, 1974

By P. C. Good

The work reported here was undertaken by the Federal Bureau of Mines to investigate new methods of preparing high-purity metal. Tungsten hexachloride was prepared by direct chlorination of scrap tungsten metal and by treating tungstic oxide with carbon and chlorine. The resulting tungsten hexachloride was purified by distillation and reduced win: sodium, magnesium, or hydrogen. The metal prepared by these techniques was at very high purity after arc melting but of variable quality prior to arc meIting. Metal recovery ranged from about 40 to 90 percent of theoretical values, It was found possible to deposit a smooth, dense coating of high-purity tungsten on the inside of a heated tube by vapor-phase reduction of tungsten hexachloride at reduced pressure.

Jan 1, 1961

By M. M. Tilman

Etchants containing hexavalent chromium and sulfuric acid are used in a variety of surface-finishing operations. When the resultant spent solutions are discarded, substantial quantities of chromium are lost and pollution prob¬lems are created. To minimize the undesirable environmental effects while improving metal and minerals recycling technology, the Bureau of Mines is con¬ducting research on a method for the economic inplant recycling of these waste etchants. Trivalent chromium, produced when the etchant reacts with a substrate, is oxidized in the anode chamber of a diaphragm cell; other metals, dissolved during the etching operation, are transferred to the catholyte. When waste brass etchants are treated in this manner, all of the trivalent chromium is oxidized and more than 40 percent of the copper and zinc is removed. Similar copper removal and chromium oxidation are achieved with waste printed circuit board etchants and rinse waters from plastic etching operations. The electrical energy needed to regenerate 1 kg sodium dichromate is less than 9 kwhr. Regenerated brass etchants evaluated by two companies equaled or exceeded the performance of fresh etchants.

Jan 1, 1979

By Willard J. Tesch

The borehole surveying system described is used to measure ground movement over and near operating mines. The magnitude of any movement is con-trolled by the ground conditions, the mining method, and the mine progress. By correlating these factors with the measured movement, equations can be determined for predicting the effect of mine progress on the surrounding ground. These equations can also be used to predict the effect of mining a similar deposit with similar ground conditions. The borehole surveying system is used in cased boreholes to measure the inclination of the hole in two perpendicular planes. Grooved casing with an inside diameter of 3 inches is grouted in the hole. Two probes are used to obtain the data necessary to calculate the hole position versus depth. One of the probes contains a gyroscope, and the other contains a biaxial force-balance [s]ervoaccelerometer. Readings from the transducers in the probe are punched on paper tape by an automatic data acquisition system as the probe is pulled up the hole at 30 feet per minute by an electric winch. Readings from the inclinometer probe containing the accelerometer are used as input data to an on-line programmable calculator as they are punched on tape. The calculator computes preliminary results of the survey being made. The paper tapes obtained during the survey runs are later used as input to a computer that computes the offsets of the drill hole versus depth in true north-south and east-west planes. These offsets are printed for each foot of depth. Changes in these offsets between the first survey and subsequent surveys are a measure of the horizontal ground movement between the surveys.

Jan 1, 1976

By Oliver Bowles

"Score of the Bureau's Investigations.There has been outlined in a previous report* the results obtained regarding the adaptability of pulverized waste slate as a filler in road asphalt mixtures. As pointed out in that report the percentage of waste at slate quarries is very high, and the Bureau of Mines has undertaken the problem of discovering new and enlarged outlets for the waste material.Many products such as paper, rubber, road asphalt, floor coverings, paints, etc., require as one of their important constituents a considerable percentage of finely pulverized inert mineral matter to give ""body"", to obtain the desired consistency, or to supply the necessary wearing or other qualities demanded. Such materials are known as ""fillers"". The possibility that slate flour might be used as a filler with advantage in several products other than road asphalt led the Bureau to undertake further investigation.The Importance of Discovering Advantageous UsesIt has been found that in some products slate may be substituted for materials now in use without any marked effect on the quality of the products. A wider use of slate in such products could result only from a definite price advantage as compared with other fillers. Mile it is probable that waste slate may be placed on the market at prices which will encourage its wider use, it is evident that a waste slate utilization industry can never attain sufficient magnitude to definitely assist the slate producers unless it is demonstrated that some definite advantage in quality may be gained when slate is substituted for fillers now in use. The main purpose kept in view throughout the inquiry has been, therefore, to find advantageous uses for waste slate in order that both producer and consumer may be benefited."

Sep 1, 1921

By Frank G. Horino

A rock mechanics program (composed of laboratory and field tests) was initiated by the Bureau of Mines in an effort to determine the causes of pillar instability at the Fletcher mine, near Bunker, Mo. Compressive strength, Young's modulus, shear strength, and the angle and coefficient of internal friction were determined on drill cores obtained from 16 different locations in the mine. Results of the laboratory tests showed that highly mineralized zones and brecciated zones in pillars could significantly affect pillar strengths and stability in locations where extraction ratios exceeded the normal design ratio of approximately 78%. High-angle fractures that were present in Some locations also may have contributed to pillar deterioration. In the field tests, in situ stress determinations were made in one pillar to establish the pillar-loading conditions and to evaluate the stability of the pillar. Continued monitoring of stresses in the pillar showed a gradual decrease in compressive stress, indicating that the pillar was probably in the postfailure state. A second stress determination was made in a vertical hole in the underlying igneous rock that was exposed on one section of the mine. Horizontal stresses were compressive and larger than would be expected from gravity loading.

Jan 1, 1978

By Charles C. Hwang

In this Bureau of Mines report, a previously developed theory of reverse stratified flow in ventilated duct fires is applied to mine-related ventilation systems that utilize an exhaust fan to supply the forced airflows. The coupling between a fire and the ventilation airflow in a single-entry duct is analyzed to relate the air velocity in the absence of a fire to air velocity during a fire. By combining the derived coupling equations with the results of the previously developed theory of reverse stratified flow, it is possible to calculate critical flow velocities required to prevent reverse stratified flow in the event of a duct fire. The sample calculations shown agree with the few experimental results available from small-scale tunnel fires.

Jan 1, 1978

By Irving Hartmann

Rock-dusting of coal mines is a most important safety measure for preventing or limiting the propagation of explosions. The Bureau of Mines has recommended for many years that rock dust be distributed on the top, ribs, and floor of mine entries and other workings of all bituminous coal and lignite mines in sufficient quantities to maintain the incombustible content of the dust above the minimum requirements. Rock-dust barriers constitute a secondary safeguard used occasionally to complement generalized rock dusting at entrances to panels and side entries or at other locations. In general, rock dust can be applied effectively with modern rock-dusting machines. However, in thin coal beds, in certain back entries, and in some other areas, rock-dusting machines cannot be used conveniently. Furthermore, many small mines find the purchase of machines costly. In such cases, rock dust is not used at all, or else it is distributed by hand, a relatively slow and costly procedure. In recent years some coal mines have started applying rock dust with the aid of permissible explosives. This may be done in various ways. One method consists in placing a stick of explosive on the floor of a room or entry midway between the ribs and covering the stick with two bags of rock dust that are slit on top and set crosswise one above the other. The explosive is then fired, causing the rock dust to be distributed on the nearby roof, rib, and floor surfaces. The procedure is repeated at desired intervals until the entire area is rock dusted. The method is claimed to be rapid, safe, and inexpensive.

Jan 1, 1950

By Hylton R. Brown

Advertisements and articles in technical and trade journals announce the approach of a new age, in which plastics, light metals, laminated wood, and numerous other products or byproducts will be used in the construction of automobiles, airplanes, and furniture and equipment used in our factories, offices, and homes. Undoubtedly, after the war there will be many such developments which will introduce new manufacturing methods and new hazards to challenge the safety engineer. Already we know, from experience in laboratories and pilot plants where these new products are being tested, that there will be many fire and explosion hazards to be overcome. The danger of dust explosions may be one of the principal hazards, because thetic resins and other materials used in the plastics industry, as well as metal powders, wood dust, and other finely divided substances, are capable of forming explosive mixtures in air. Heavy losses of life and property have been caused by dust explosions in flour and feed mills, starch factories, and grain elevators, and it will be well to consider the possibilities that such losses may occur in any new industry and to provide all possible safeguards against hazards. Fortunately, we have learned something about the behavior of dust explosions and know something about the ease of ignition, limits of Explosive concentration, end pressure developed. Our efforts should now be directed toward the application of this knowledge in the development of safe operating practices.

Jan 1, 1945

By Fremont F. Clarke

"INTRODUCTION Clay beds of southwestern North Dakota were investigated to determine (1) the average alumina content of the clays in four principal areas of occurrence, (2.) which, if any, would be the most feasible method of extracting alumina from the clays, and (3) whether the clays had any other commercial uses.During the investigation exposed sedimentary beds were examined for clay and the thickness and areal extent of outcropping clay beds in the more promising areas were measured. Four-principal areas of bentonitic clays, comprising 6,967 acres in Stark, Slope; and Billings Counties, N. Dak., were mapped and sampled.ACKNOWLEDGMENTSIn its program of investigation of mineral deposits, the Bureau of Mines has as its primary objective the more effective utilization of our natural resources to the end that they make the greatest possible contribution to national security and economy. The Mining Division, Lowell B. Moon, chief, conducts preliminary examinations, does the actual investigative work, and prepares the final report. The Metallurgical Division, Oliver C. Ralston, chiefs analyzes samples and makes beneficiation tests.Acknowledgment is duo John P. Gries, professor of geology, South Dakota School of Mines and Technology, for his studies of and advice on geological phases of the work. His data were drawn on freely in preparing this report; also E. D. Gardner, regional engineer, Rolla, Mo., and E. Y. Dougherty, district engineer, Rapid City, S. Dak., for assistance and advice in supervising the program."

Mar 1, 1948

By R. L. Montgomery

The literature has been surveyed and values recalculated for the heats and free energies of formation of solid rare-earth compounds at 298° K. In most instances it was necessary to estimate the entropies. Thermodynamic properties of aqueous rare-earth ions have also been calculated. INTRODUCTION The accumulation of thermochemical data on rare-earth compounds in recent years makes it possible to review the subject and to obtain more consistent and more reliable information than was available previously.

Jan 1, 1959

By Lowell B. Moon

Regardless of how a mineral deposit in first discovered or by whom, any mining enterprise based upon it must pass through a preliminary stage of exploration. The common understanding of ?exploration? among mining engineers is well-expressed by Jackson and Knaebel:3/ Exploration work ranges from that performed by the individual prospector employing only the simplest tool, and equipment to elaborate campaigns involving the expenditure of largo stuns of money end the use of churn- car diamond-drilling equipment, large test-pitting crews, or sometimes a regular mining organization. In any event, the object is to determine as accurately as possible, with the funds available, the size, shape, and other characteristics of the ore bodies and their average value or grade.

Jan 1, 1945

By W. J. Fene, H. B. Humphrey, J. J. Forbes

"INTRODUCTION Loss of life from coal-mine explosions in the United States in 1949 was the lowest in any year since before 1870. Although fatality reports from coal nines before 1910 were incomplete,' the explosion fatalities from single disasters or individual States exceeded the 1949 total in each year as far back as 1870, when the records become fragmentary. Since 1890, the only other year in which fewer than 35 were killed was 1946, with a total of 32. Figure 1 shows the total yearly fatalities from explosions in all coal mines and those in anthracite mines alone since 1870. The fatalities in bituminous coal mines were not completely reported before 1910, but enough reports were issued by major coal-producing States to compile reasonably representative figures back to 1885. Any corrections would be additions to these totals.The reason for the moderate total of 46 explosion fatalities in 1948 and the low total of 8 killed in 1949 is thought to be the serious and careful attention devoted to elimination of coal-mine explosion hazards after the disastrous explosions in 1947. The standards now being observed generally with respect to ventilation, rock-dusting, and inspections for gas are better than those found earlier in even the mines having the best reputations for safety. Exceptions are still numerous, but they are fewer, month by month, because of the pressure of Federal and State inspections and a changing conception of the hazards that should not be permitted underground. The prevailing precautions have not eliminated all ignitions of gas or dust, but they have limited propagation to small explosions and have prevented serious loss of life.The number of ignitions (14) reported for the year was less than the average (24) for the 5 years 1944-48 and only half the average for the fiscal years 1929-44. Another favorable factor is that Bureau of Mines representatives were probably in closer contact with both small and large mines in nearly all coal-mining districts. Inspectors now assigned to individual districts are better able to keep informed on the happenings and the progress of safety in their districts. In 1948, one-fourth of the explosions were in mines that employed fewer than 10 men; this condition was duplicated in 1949."

Jul 1, 1950