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By J. R. Thoenen

This paper outlines briefly results of seismic measurements recorded in the vicinity of quarry blasting under practical operating conditions. The data cover field work done from January to the middle of August 1930, during which time records were made of 61 blasts in 19 quarries. Of the tests made, one was in biotite-gneiss, two in dolomite, two in a flintlike volcanic complex, three in gabbrodiorite, five in trap rock, and six in limestone. One quarry was in Alabama, two were in South Carolina, two in New York, four in Kentucky, five in Connecticut, and five in Massachusetts. Explosive charges ranged from 0.30 pound to 41,900 pounds, and the method of shooting varied from mud caps through hammer and wagon drill holes to churn drill holes and coyote tunnel shots.

Jan 1, 1937

By W. G. Pariseau

A two-dimensional finite element program has been modified and extended to account for some of the rock mechanics complexities associated with single entry development of longwall coal mine panels. Program capability includes arbitrary assignment of element properties without regard to element ordering, anisotropic elastic, plastic and brittle rock properties that may be time dependent (aging), arbitrary mining sequences and provision for the effects of artificial support on the adjacent strata. Failure is according to an extended von Mises criterion that may be linear or quadratic in form; flow rules are obtained from the yield function taken as the plastic potential, but brittle behavior is treated as a discontinuous process of material properties change with deformation. In either case the extent of failure is calculated from the external boundary conditions. Application of the program to essentially two-dimensional problems resulted in lose agreement between calculated displacements and field measurements in the double entry system. Bleeder entries were stable in one locality and not in another. Artificial support had little influence on stability.

Jan 1, 1978

By Norma Golumbic

The primary purpose of the Bergius (hydrogenation of coal) and Fischer-Tropsch (hydrogenation of carbon monoxide) processes is the production of synthetic liquid fuels. This objective is of importance in insuring an adequate supply of motor fuels and lubricating oils in the United States. In the urgency of the basic research and process development work on synthetic liquid fuels, the possibilities for the production of synthetic chemicals inherent in these processes have hitherto received little attention in this country. However, the by-products, as well as the primary products, from the Bergius and Fischer-Tropsch processes are rich source materials for organic chemicals. The overhead oil from liquid-phase hydrogenation of coal, for example, contains benzene, toluene, xylene, cyclohexane, methylcyclohexane, aromatic solvents, about 20 percent tar acids (largely phenol, cresols, and xylenols), and 3 percent nitrogen bases. Wax, alcohols, and acids are by--products of the Fischer-Tropsch synthesis. In addition, techniques have been developed which make possible the production of aliphatic hydrocarbons, alcohols, acids, aldehydes, and other oxygenated organic compounds. These chemicals are more valuable on a unit basis than gasoline. Because of continued rapid expansion of the plastic, resin, lacquer, and solvent industries, larger amounts of many of these chemicals will be needed in the near future.

Jan 1, 1949

By R. R. Faddick

A mineral slurry data hank has been compiled, containing slurry pipelining data on sixteen ores, concentrates, and tailings. The data bank it in the form of a computer print-out all they necessary system constants and headloss data for each mineral commodity. The purpose of the data bank was to assist in the development of a universal head loss correlation for mineral slurries, if such a thing exists. Present headloss correlations were tested and found to be inconsistent for the various mineral slurries. Consequently, a different approach was taken, that of compiling a library or Stanton diagrams relating friction factor and Reynolds numbers for a given slurry in a given pipe diameter. The advantages of the diagrams arc demonstrated and discussed. While this correlation shows excellent potential, it is necessary that additional work, both theoretical and experimental, be performed. In addition, two equations are given from which a design velocity may be obtained to minimize deposition or formation of bedload. The equations are based on data taken from the mineral slurry data bank.

Jan 1, 1972

By Henry H. Ginsberg

The Federal Bureau of Mines made pilot plant investigations of the process requirements necessary to produce heavy fuel oil by the liquid-phase hydrogenation of bituminous coal. The investigation was carried out in three separate series of experiments. The first series studied the effect of temperature and contact time on product distribution at 3,500 p.s.i.g. and 420° to 480° C. in the presence of 0.1 wt.-pct../ stannous sulfide plus 0.05 wt.-pct. iodoform based on gross coal. As a result of increased contact times and temperatures, the conversion-6/ and yield of hydrocarbon gas increased, the viscosity of product oil decreased, and elimination of oxygen, nitrogen, and sulfur from coal increased. The yield of oil did not indicate any definite trend with changes in temperature and contact time. The yield of oil ranged from 76 to 85 pct. for Pittsburgh coal and from 60 to 85 pct. for Rock Springs coal. Asphaltenes in the product oil ranged from 17 to 38 pct. of the total oil for Pittsburgh coal and from 12 to 22 pct. for Rock Springs coal. Fuel oils meeting Bunker C or American Society for Testing Materials (ASTM) Grade 6 specifications were produced with Rock Springs coal at 0.2- to 1.0-hr. contact time and 440° to 480° C. and with Pittsburgh coal at 0.3- to 1.0-hr. contact time and 420° to 460° C. In the second series of experiments tin, nickel, iron, and zinc were evaluated as catalysts for the hydrogenation of Rock Springs coal to heavy fuel oil at 3,500 p.s.i.g. and 460° C. Using the apparent conversion of coal as criterion of catalyst activity, at a contact time of 0.45 hr. tin was the most effective catalyst; nickel and iron were nearly as effective, but the use of zinc resulted in much lower conversion. When the contact time was increased to 0.80 hr., the apparent conversion of coal was essentially the same for each of the catalysts. When the yield of oil boiling below 3550 C. was used as criterion of catalyst activity, at 0.45 hr. the order of activity was tin, iron, nickel, and zinc; at 0.80 hr. tin was far superior and the others were essentially equal. The product oils contained from 8 to 20 pct. asphaltenes.

Jan 1, 1960

By D. W. Scott

Thermodynamics is a powerful tool for investigating rotational isomerism in substituted ethanes and related molecules. Accurate calorimetric data can be interpreted to give information, not only about the energy difference between conformations, but also about the shape of the potential barrier hindering rotation from one conformation to another. However, a deterrent to this use of thermodynamics is the labor required to calculate the contributions to the thermodynamic functions for assumed potential functions. Tables of thermo-dynamic contributions for appropriate potential functions can eliminate that labor and greatly facilitate the thermodynamic study of rotational isomerism. In this research, tables of contributions to the thermodynamic functions were compiled for two potential functions typical of some commonly encountered examples of rotational isomerism. TYPES OF POTENTIAL FUNCTIONS Potential function 1, illustrated in figure 1, A, has two equal minima higher than the third. It has the general shape of the barrier to internal rotation in n-butane, for example. The trans conformation of n-butane has the lowest energy, and the two skew or gauche conformations have equal but higher energy. Potential function2, illustrated in figure 1, B, has two equal minima lower than the third. It has the general shape of the barrier in 2-methylbutane, for example. The two C1 conformations of 2-methylbutane have equal energy much lower than the assumed Cs conformation, which has not been observed spectroscopically.

Jan 1, 1962

By J. A. Lamonica

The Bureau of Mines conducted an environmental noise survey to determine the noise levels to which underground coal mine employees are exposed, to evaluate noise survey techniques and equipment, and to compare noise exposures using two criteria, Walsh-Healey and CHABA, for determining allowable exposures that were under consideration for the Federal Coal Mine Health and Safety Act of 1969- Time study techniques and Bureau-approved standard sound level meters were employed. The shift exposures of 20 percent of the miners studied were in excess of the safe standards established by both criteria. The shift exposures calculated using the Walsh-Healey criteria were greater than those calculated using the CHABA criteria owing to the intermittent nature of the exposure. Ultimately the CHABA criteria were rejected, and the Walsh-Healey criteria were adopted.

Jan 1, 1971

By John W. Colburn

A tractor-integrated version of an explosive ripping system was developed for mining application. This system utilizes diesel fuel and a tractor-mounted blower supplying 30 psig compressed air to a two-stage combustion chamber to produce a high pressure (600 psia) gas charge. The charge is rapidly released into the rock formation near the tip of the ripper. The system, mounted on a D9 tractor, was tested at several quarry and mining operations to investigate rock fracturing effectiveness. Although the results of comparative ripping passes conclusively demonstrated that the system increases rock fracture, performance of the system is strongly dependent on rock morphology and properties as well as basic performance of the tractor-ripper. The theory of conventional and explosive ripping modes is described and existing correlations of seismic velocity and ripper performance are shown to be in error.

Jan 1, 1977

By J. J. Shields

This study by the Federal Bureau of Mines concerns different methods of face haulage used with various types of continuous-mining machines, mobile-loading machines, and track-mounted equipment under varying roof and bottom conditions and in coalbeds of varying thicknesses. This report is the ninth in a series on mechanical mining in bituminous coal mines. Reference to the reports previously published is made in appendix III, p. 106. Use of modern mining equipment in bituminous coal mines has resulted in increased productivity at the face. This especially is true where continuous-mining machines are used, and the supervision is good. Previous methods and equipment for moving coal from the face became inadequate and had to be improved to restore balance to the mining systems. Sometimes new equipment was needed to improve the face haulage, and in some instances, a new combination of existing equipment was used. Detailed studies of face haulage methods were made at 13 mines in Pennsylvania, West Virginia, Ohio, and Illinois to compare their effectiveness and to describe fully the conditions under which each method was used.

Jan 1, 1960

By Steven A. Hawkins

This report details the conduct and results of a 5-month study to collect data on the use of steel support for ground control in European underground coal mines. The report summarizes European steel support design practices and describes the applicability of steel supports to U.S. mining conditions.

Jan 1, 1980

By Bruce Pinkston

This report presents a description of the Prototype Demonstration Vehicle developed under U.S. Bureau of Mines Contract No. JO 366003, "Improving Man Transit Safety". This vehicle was constructed to assess the feasibility of a set of equipment related guidelines which were drafted in Phase I of the same contract. State-of-the-Art improvements were embodied in such areas as collision survivability, occupant comfort, and multiple mode (on and off rail) operation. The electric battery-powered vehicle carries a twelve man section crew at speeds up to 12 mph. The description of the demonstration vehicle is presented in Volume I. Safety Guidelines are presented in Volume II.

Jan 1, 1981

By William C. Cooley

This study Identifies and evaluates deposits of noncoal minerals in the U.S. which are most amenable to be mined underground hydraulically and transported hydraulically. A method was developed to screen and compare mineral deposits including economic comparisons. The most applicable minerals for hydraulic mining by borehole monitor jets from underground entries are soft uranium sandstones In Wyoming in locations where water is available. This method with hydrotransport could improve the safety, health and economy of underground uranium mining. Soft oil-bearing sandstones in California and Texas could be mined and transported by this method more safely than by other underground mining methods. Other weak sandstones may be hydraulically mined economically. Man, minerals are too hard to be mined by monitor jet but are amenable to hydraulic transport and hoisting. Uranium sandstone in New Mexico is of interest because of potentially improved health and safety in transport and lower transport cost, Increases in mine output for potash, in New Mexico and trona in Wyoming can be achieved most economically by adding hydraulic hoisting when existing skip capacity is at its limit. Research is recommended to obtain site-specific data on the feasibility of mining uranium ores by monitor jets.

Jan 1, 1981

By Richard L. Ash

Introduction The blasting capabilities of commercial explosives are often rated according to their loading densities and detonation velocities. Both the density and velocity are relatively easily measured, the values of which can be used for determining the approximate detonation pressure developed by an explosive during any given set of blasting conditions (1-5). Knowledge of the actual rate of detonation attained at all points along a charger's length also is considered to give a good indication of how well the explosive is functioning. Many factors affect the density and velocity and have been thoroughly discussed by various authors (4, 6-12). For recording velocities several methods are available, but the resistance-wire, or probe, continuously recording technique has the distinct advantage of providing a record of the complete progress of an explosive reaction from the time it first initiates. Figure 1 is a copy of a typical record obtained by the procedure with certain significant information indicated. The theory and applications of the method are extensively covered in the literature so need not be reviewed for this report (13-18). Only the specific equipment and procedure employed for this investigation are presented.

Jan 1, 1973

By Meliton M. Garcia

The volume of gases produced in major and trace amounts following the detonation of two water gel and two emulsion explosives in a mine were determined. The volume .of the major gases (CO, CO2, NO, and NO2) was measured immediately following detonation, during the mucking operation, and following the removal of the muck. Tests to identify and quantify the gases produced in trace amounts were performed following the detonation only. The volume of each major gas per pound of explosive (ft /lb) ;ranged as follows: CO, 0.0424-0.3231; CO , 0.6819-1.5632; NO, 0.0129-0.1320; and NO2, 0.0019-0.1111.. An approximate average of 95% of the gases produced was found in the test chamber immediately following the detonation, while less that 2% was found in the chamber following removal of the muck. Benzene was the most significant compound found to occur in trace amounts. Scaling tests performed with a water gel and an emulsion explosive suggest that the volume of the gases per unit mass of explosive detonated diminishes as the amount of explosive per blast increases.

Jan 1, 1986

By D. J. Dollhopf

This research was part of an effort to investigate means of reestablishing non¬polluted hydrological systems in areas where surface mining directly impacts shallow ground-water resources. Chemically undesirable overburden material was selectively backfilled with the intent that it would be below the future root zone, be above the reestablished aquifer, and would not be leached as a result of deep percolation. After 2 years the buried material remains above the spoil aquifer and below the maximum rooting depth. Unsaturated water flow from the land surface to the buried material occurred during wet climatological periods. No significant leaching of buried material was observed, however. Overburden sample contamination from drill stem joint grease with Pb, Zn, and Cu additives caused substantial error regarding DTPA extractable trace metals. A grease with teflon and talc additives was recommended for use in future sampling programs. DTPA extractable trace elements in overburden material had no statistical relationship to post-mine ground-water quality. Overburden columns leached with water produced leachates comparable to overburden and spoil ground-water trace metal quality. A depositional model described the Rosebud Coal overburden as a fluvial system with distinct units of sand, silt, and clay, with distinct chemical properties. Physical and chemical characteristics of the model were comparable to the in situ geochemical system, a relationship which may aid in locating overburden materials unsuitable for reclamation.

Jan 1, 1979

By Rupert O. Yantz

This report, authorized under contract Number H0111403 Amendment Number One, entitled, "Exploration of Illumination Concepts for Underground Coal Mines", contains the results of an investigation of methods, procedures, and technology for providing working place lighting in underground coal mines and construction of a prototype, man portable, mine illumination system and a prototype, machine mounted, mine illumination system for use in high and low coal entries of underground coal mines.

Jan 1, 1972

By G. E. McElroy

The purpose of tins paper is not to present new date on the pressure losses due to bends and chances of area in mine openings through which air flows, but rather to correlate existing data, determined mainly on small duct systems and expressed in a variety of ways, according to uniform methods that facilitate their use in pressure-loss computations. These are required in such, air-flow problems as determining the quantity that will flow through is mine openings under a certain pressure difference or, conversely, the pressure difference that will be required to maintain a certain rate of flow. Air flowing through h ducts, such as mine airways, encounters resistance to flow due to interference of the individual air streams with each other caused by the wall surfaces. The result is that part of the kinetic energy of the flowing stream is converted to heat; and constant renewal of the kinetic energy from the total energy of the flow is required to maintain it. This process manifests itself by a decrease of the total pressure (static pressure plus velocity pressure; of the air in the direction of flow; in order that flow pray occur, there must necessarily be a differences in total pressure between the two cads of the air-ay equivalent to the pressure losses occasioned by the flow, which automatically adjusts itself in magnitude to the pressure difference maintained.

Jan 1, 1932

By Jack Touseull

On November 15, 1972, the Bautsch mine, a lead-zinc mine in Paleozoic dolomites, experienced a massive rock failure involving 3 to 5 million tons. Because this failure was large and extended to the surface, it was included in the Federal Bureau of Mines investigations on "Massive Rock Failures." Analysis of the rock mechanics and mode of failure revealed that failure at the Bautsch mine was the result of the interrelationship of many factors. Factors related to the failure were found to be external and internal to the mining environment. Unlike internal factors, external factors were not apparent and, therefore, many external factors were investigated; some of which are not normally considered in rock mechanics analyses. External and internal factors determined to be of significant importance were: (1) precipitation, (2) fractures, (3) plastic clay layer, (4) topography, (5) rock alteration, (6) bedding, and (7) mining zone dimensions. Because of the conditions at the mine, failure could have been predicted without extensive instrumentation. Application of basic geologic and engineering principles to the internal and external factors could have predicted failure. Alternately, failure would, in all probability, have been delayed by years if, after 1962, mining had been curtailed in the area of failure.

Jan 1, 1980

These proceedings consist of papers presented at two Bureau of Mines Technology Transfer Seminars for the purpose of disseminating recent advances in mining technology related to coal mine fire and explosion prevention. Primary, although not exclusive, emphasis is placed on underground coal mining. The papers address research accomplishments ranging from methods for detecting mine fires to remote sealing systems for extinguishing coal mine fires. Each paper represents the current state-of-the-art in the respective research categories. Presentations include research occurring from both Bureau in-house and contract efforts.

Jan 1, 1978

By Oliver Bowles

Sandstone, a widely distributed siliceous sedimentary rock, is the third most popular building stone in the United States. It is formed by the breaking down of preexisting rocks by weathering, subsequent segregation of the detrital quartz grains into discrete deposits by the sorting action of water or wind, and finally cementation of the quartz sand into a coherent rock. The homogeneity and resistance to weathering of the resultant sandstone make it suitable for exterior construction. Its excellent wearing properties explain its popularity for flagging and stair treads. However, quarrying and dressing methods and costs are adversely affected by the abrasiveness and hardness of sandstone especially as compared to limestone.

Jan 1, 1963