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By W. M. Weigel

"Sand is one of the commonest materials for industrial use, not only as a building material, but in many industrial processes. The general name applies to all grades, from the comparatively impure, unsorted product used in concrete, to especially sized products of extreme chemical purity. Various definitions have been proposed, all more or less open to objection, as they fail to cover special applications. One is: ""Sand - The fine granular material naturally or artificially produced by the disintegration or crushing of rock or slag"". This does not fit the definition of sand as understood by geologists, who consider sand only as a naturally formed product. Another is: ""Sand - The fine granular material naturally produced by the disintegration of rock"". This does not take the chemical com-position into account, and for practically all uses, except in concrete and plaster products, a material composed predominantly of silica or rather quarts is implied.Sand for special purposes usually requires different methods of preparation from those where the ordinary mixture of sizes as naturally occurring are suitable. One of the classes requiring the most uniformly sized grains is sand blast sand.Sand Blast SandThe use of the sand blast has increased rapidly during the past few years. It was formerly used almost entirely in the foundry to clean and remove inequalities from rough castings. This is still the most important application, but in addition, it is now employed for the removal of paint from old surfaces, carving and engraving on stone and marble, glass cutting, cleaning or renovating the rails of stone and brick buildings that have become discolored, preparing the surface of metals for the electrolytic bath, putting the final finish to metal surfaces, and has even been proposed as a means of channeling or cutting out blocks of stone in the quarry."

Jun 1, 1924

By Samuel B. Flagg

The Bureau of Mines is endeavoring to ascertain how mineral fuels in which the Government has a direct interest, by ownership or use, can be utilized with highest efficiency. For this reason the bureau has been, and is, carrying on investigations to ascertain the condi- tions of furnace construction and management that are necessary to insure the smokeless combustion of the different coals that are found in public lands or are purchased for Government ships and power plants. Another reason for the bureau undertaking these investigations is the need of better furnace management and a more careful selec- tion of fuel at many Government plants. There are Federal build- ings in hundreds of cities. The coals available at many of these cities differ greatly in quality, and the furnaces in some of the Fed- eral buildings were not designed for efficient utilization of the cheap- est available coal. Hence, some of the boiler plants smoke badly unless fed with low-volatile coal and have caused repeated com- plaints not only from neighboring property owners who have suffered damage, but from persons endeavoring to create a civic pride in clear air. In the course of its fuel investigations the bureau has noted the conditions governing fuel consumption in different cities and has studied the attempts made by these cities to abate smoke through the passage of ordinances imposing penalties on smoky stacks. Some results of that study are presented in this report. The most im- portant conclusion reached is that smoke abatement by ordinance can not hope to succeed unless supported by public sentiment and that a smoke ordinance should look to future prevention rather than to immediate prohibition. In other words, strict control of furnace construction offers much greater hope for smoke abatement than desultory imposition of severe penalties on the escape of "dense" or "black" smoke.

Jan 1, 1912

By S. H. Brooks

"IntroductionThis preliminary report deals with the effect of oxygen pressure on the ignition temperature and combustibility of oils, it is the third of a series which will present the results of an investigation being made by the Bureau of Mines, on oxygen-oil explosions. The purpose of this research is to obtain technical data that will serve as a basis for safety precautions general outline of the problem has been given in the first report (Serial 2507).The present experiments have resulted in (1) a method for determining spontaneous ignition points of oils in an atmospheric of oxygen under pressure; and (2) the determination of these ignition temperatures for three typical oils, one being an animal oil (sperm), one a vegetable oil (linseed), and one a mineral oil (""Moiloil A"").These experiments on explosibility of oil were performed in order to discover the general nature of the phenomenon, especially the order of magnitude of the temperature necessary for spontaneous explosion (120°C. and upwards) and the effect of pressure variation (negligible as regards ignition temperature but important in relation to the violence of the explosion). A continuation oftests should provide a basis for selecting the safest lubricants for high pressure compression of gases particularly air and oxygen; and should be of value when devising new specifications for lubricants, both in the government departments and the compressed-gas manufacturing industry."

Dec 1, 1923

By Alan A. Bergeron, J. L. Michels, R. L. Collins

Advanced communication and monitoring systems were developed and demonstrated in three underground mines representing different mining techniques, geographical areas, and material mined. The first mine was a large coal mine in western Pennsylvania that used room and pillar techniques and continuous mining methods. The system developed for this mine provided private telephone channels, environmental monitoring, and control of underground equipment, all on a single coaxial cable, with all system operations under the direction of a minicomputer. Many advanced features were incorporated into the system, such as paging of roving personnel, two-way section wireless, through-the-earth emergency communication, and redundant signal paths. Television was multiplexed into the system for underground equipment surveillance. A hoist radio system completed the complement of equipment at the mine. The second mine was a magnetite ore mine in eastern Pennsylvania that used block caving mining techniques. A radio system was developed that provided two-way communications between trackless vehicles and roving personnel. A unique system of uhf/vhf repeaters combined with a flleaky-feeder" transmission line offered operational and emergency features not previously found in mine communication systems. Evacuation alarming, personnel paging, fan-hole drill operator communications, and maintenance and safety vehicle dispatch were provided. The system required no dispatcher and operated during power failure. A hoist communications/shaft inspection system completed the installation. The third mine was a deep silver mine in the Cour d’Alene district of Idaho. The system developed for this mine utilizes a single wire pair to provide up to 14 voice channels. A unique combination of PBX, telephone carrier system, and intercoms offered private conversations, selective signaling, and emergency backup communications. Two hoist communication systems were installed to provide a voice link and in-cage belling signal between hoistman and cage.

Jan 11, 1981

By Gary R. Gavan

This report presents the documentation and User's Manual for a data retrieval and report generation computer program. The program operates on a data base containing over 19,000 pieces of coal mine equipment in use in 1976.

Jan 1, 1979

By C. C. Clark, R. R. Backer, J. D. Vickery

This report presents the results of tests conducted by the U.S. Bureau of Mines to determine the transport characteristics of highly concentrated paste backfill mixes made from dewatered total mine tailings. The slurry concentrations of the mixes were all above 78 pct by weight with slumps ranging from 6.4 to 16.5 cm (2.5 to 6.5in). Laboratory material property tests and full-scale pumping tests were conducted using pipe diameters of 102,128, and 154 mm (4, 5, and 6 in) and a positive-displacement pump. The results indicated that the tested backfill mixes can be successfully transported as a stiff paste and identified the influence of and the interaction among the various mix and system variables.

Jan 1, 1995

By A. W. Deurbrouck

Four samples of Pittsburgh-bed coal, of various size consist and ash content were dewatered in a pilot-size vacuum-disk filter partially enclosed with a steam jacket. Steam fed at 2.5 to 12.5 pounds per minute reduced the moisture content of the filter cakes from 2.8 to 13.8 percentage points more than normal vacuum dewatering. Approximately 1.5 pounds of steam was required to remove 1 pound of water.

Jan 1, 1966

By Louis H. Berkelhamer

"INTRODUCTION The method of differential thermal analysis suggested by Le Chatelier (1)1 in 1887 has recently emerged as an outstanding means of studying the constitution of various substances, particularly clays, soils, and miscellaneous hydrous materials (2). The literature ably discusses the applications and results obtained but has paid too little attention to specific details of construction of the apparatus. Knowledge of the apparatus is of importance to the experienced research man as is extremely useful to the novice v ho ventures into this field of analysis. Further, it is generally acknowledged that the variations in design and conditions of operation are one of the essential causes for differences in characteristic temperatures as reported by various investigators. A step forward in the elimination of such differences is the publication of the details of construction and operation of a simple and inexpensive apparatus that has proved useful at the southern Experiment station of the Bureau of Mines, where it was used in cooperation with the University of Alabama, Tuscaloosa, Ala."

Jul 1, 1944

By Jr. Allan

"Although the advantages of large-capacity air receivers for underground mines are plainly evident from published information about various installations in the United States and abroad, details of their construction are not generally known in this country., Ordinary present-day air-compressor installations servicing mining machines are designed to supply air at a specified pressure in sufficient quantity to meet the peak demand of the mine,2/ although this demand may exist for only a few minutes out of 24 hours and, as usually happens, eventually exceeds the capacity of the compressor. Most of the receivers provided with these compressors (to a certain degree of standardi¬zation) are capable of storing a volume of air approximately equal to that compressed in 1 minute by the machine.3, 4/ As a result, during peak-load periods the compressor operates at full load capacity without maintaining kick-off pressure. At other periods of the work cycle, production of compressed air is intermittent.At least one large mine5/ has adopted large-capacity receivers to reduce wear on its air-compressing system caused by the sudden demand of peak loads. Under the old system, the compressors jumped suddenly from half speed to full speed; boilers furnishing steam to the compressors were taxed heavily to provide the increased requirements of power; and machines using the air, among which were four large hoists, were required to operate at 65 pounds per square inch rather than at the 90 pounds per square inch for which the compressors were regulated. Operation of air machines, especially drills, at pressures lower than those for which they were designed decreases their efficiency and increases maintenance costs. In addition, air that comes directly from the compressors has had little opportunity to cool and dry enroute.6./ As a result, quantities of compressor lubricant and water are carried into the machines that use the air. When expansion occurs in the cylinder or turbine of such engines, the temperature of the air drops, and this oil and water is precipitated. The water washes away lubricating oils in the machine, causing poor performance and high cost of maintenance; the compressor oil, in addition to being a poor lubricant for compresed-air engines, exerts a corrosive action on gaskets and rubber hoses.7/Reduction of peak demands on air compressors by large receivers lowers power costs by establishing more nearly constant load factors,8/ and in some cases by permitting the use of smaller compressor capacity.8,9/Load factor is the ratio of average demand to maximum demand; a low load factor costs money.10/Elimination of high-peak demands raises the load factor by making the average and the maximum demand more nearly equal. Further savings may be made possible by large receivers where their use permits charging to be done at night in regions having lower power rates during that period.11/Where ordinary receivers are used, compressor breakdowns cause immediate work stoppages in the mine owing to lack of air. Similarly, the capacity of a large receiver has been known to permit uninterrupted work in the mine until the compressors have been returned to service.9/Large-capacity receivers, either steel-tank or underground rock-chamber, offer a practical solution of many existing problems by providing a sufficient reserve of compressed air within the pressure range required for efficient operation of machines to level off peak demands on the compressor. The com¬pressors operate when the demand has reduced the pressure in the receiver below the regulating pressure and until all air used from the receiver has been replaced. It has been found possible in at least two mines,8.9/ one of which the author has visited, to entirely eliminate one compressor and to obtain more efficient performance from the remaining one by the construction of an underground coal-chamber receiver.8/"

Jan 1, 1950

By Stephen C. Brown

THE expansion of the world economy which has been in process since 1958 continued in 1963 and both production and consumption of minerals rose. Gross national product (GNP) rose sharply in the United Kingdom and Japan, continued to expand in the United States and Canada, and maintained a high though slightly declining rate of growth in the European Economic Community (EEC) despite the appearance of excess capacity in certain lines and inflationary pressures in Italy and France. The steel and motor vehicle industries both increased output in North America, Western Europe, and Japan. The less developed areas benefited substantially from an improvement in their terms of trade, and their export earnings increased some 8 percent in 1963; although estimates of GNP for the majority of them are 110t yet available, it is probable that this increase was partly reflected in a substantial rise of GNP.2 In the United States the expansion was steady and extended through all sectors of the economy producing no distortions likely to disturb its continuing growth; at yearend with unemployment still at about 5.5 percent of the labor force and operating rates of industry estimated at about 87 percent of capacity, there was a substantial margin for further expansion. Though the balance of payments was still in heavy deficit for the year, in the last half it was moving rapidly toward equalibrium as net exports rose and capital outflows declined; prices were relatively stable, inventories increased only slightly and the activity of mineral-consuming industries remained high, steel output rising by 11 percent to highest level since 1957 and the auto industry output equalling the 1955 record.3

Jan 1, 1964

By Herbert R. Babitzke

As part of a project to develop refractory metal alloys suitable for high-temperature structural applications, the Bureau of Mines applied solid solution and precipitation-hardening techniques to columbium and tantalum alloys. Thirty-three alloys were evaluated to determine their formability, strength, and oxidation resistance. Three alloys had tensile strengths near 40,000 psi at 1,200° C: Cb-1N-5W-5V-10Hf (No.4), Cb-15Hf-5W-0.5B (No. 31), and Cb-15Hf-SW-IB (No. 32). Oxidation resistance of the high-strength alloys was good. Alloy4 gained only 34 mg/cm2 at 1,200° C, and 21 mg/cm2 at 1,000° C in 2 hours. Hot forming was done without any protection from oxidation.

Jan 1, 1968

By D. E. Ingersoll

This report describes the preparation characteristics of anthracite from the Mammoth and Holmes veins in Schuylkill County, Pa., as determined by the Federal Bureau of Mines laboratory separations at specific gravities of 1.50 to 1.90. The Holmes vein anthracite contains approximately 13 percent ash, and the Mammoth vein contains about 9 percent as fed to the breaker. Crushing Broken, Egg, and Stove sizes from each vein produces Pea-size anthracite of lower ash content than that contained in Buckwheat No.1 size and smaller. The Buck-wheat No.5 size has the highest ash content of all the sizes examined. Potential recovery from a mixture of the two veins as received at the breaker, separated at 1.90 specific gravity, is approximately 64 percent of the feed at 11.0 percent ash. The same materials separated at 1.80 specific gravity yield about 61 percent with an ash content of 10.1 percent. All rejects are from the Holmes vein, because the entire Mammoth material is less than 10.0 percent ash.

Jan 1, 1960

By M. J. Ferrante

Low-temperature heat capacities and high-temperature enthalpies for syn¬thetic Cu2S and CuS were measured. This investigation is part of the Bureau of Mines goals to provide thermodynamic data essential to the more efficient processing of copper ores, and thereby minimize the current dislocations in energy, environment, and mineral supply. Heat capacities were measured with an adiabatic calorimeter from 5 to 310 K, and resulted in S°298 = 27.76 for Cu2S(c) and S°298 = 16.05 cal/deg mole for CuS(c). Low-temperature values are tabulated for Cp°, S°, -(G°-Ho°)/T, and H°-Ho°. Enthalpies were measured with a copper block calorimeter from 298.15 to 1,600 K for Cu2S(c,1) and 298.15 to 780 K for CuS(c). The thermal behavior of CuS showed no transitions or other significant anomalies for the low- or high-temperature investigations. Cu2S showed reversible transitions at 376 K with an isothermal heat absorption of 0.865 kcal/mole, 720 K with an isothermal absorption of 0.280 kcal/mole, and approximately 1,400 K (congruent melting point) with a heat of fusion of 3.070 kcal/mole. High-temperature data are tabulated for H°-H°298, Cp°, S°, and -(G°-H°298)/T. Enthalpies are also expressed in equation form. The low¬and high-temperature data were combined with data from the literature to cal¬culate and tabulate ?Hf°, ?Gf°, and log Kf as a function of temperature.

Jan 1, 1978

By C. P. Mangelsdorf

This report deals with the efforts to develop a portable device suitable for underground use for the purpose of measuring the frequency of vibration of the horizontal chords of Birmingham roof trusses. Four devices are investigated and evaluated. An approximate emperical expression developed from a mathematical analysis provides a means of converting the frequency into tension. The method appears to be effective in mines with shale roof but requires some modification for other roofs.

Jan 1, 1983

By C. E. Wethered

This paper describing the mining methods employed by the Federal Mining and Smelting Co., operating the Morning mine at Mullan, Idaho, is one of a series being prepared by the United States Bureau of Mines on mining practices, methods, and costs in the various mining districts of the United States. The daily tonnage produced at the Morning mine, including that mined by leasers, is 1,100 tons. Mine run of ore will average 9.1 per cent lead, 5.8 per cent zinc, and 4.4 ounces silver per ton. A stull set and fill method of mining is employed.

Jan 1, 1930

By T. E. Gray

This report describes the preparation characteristics of the more significant coal beds in Washington County, Pa. It is one of a series planned to determine coals suitable for producing metallurgical coke, either as mined or after beneficiation. More than 15 million tons of coal was produced in Washington County in 1956; 89.8 percent was cleaned mechanically in 10 cleaning plants. The Bureau of Mines has estimated that 2,280 million tons of recoverable coal remained in beds 28 inches thick or more as of January 1, 1954.

Jan 1, 1959

By H. K. Kutter

The pressure pulse generated by an underwater spark \vas investigated in relation to its potential use for rock fragmentation. The study established (1) the relation between the peak discharge current and the peak wave pressure; (2) the relationships among the peak wave pressure, the discharge voltage, and the spark gap width; (3) the type and pulse duration of the generated wave; (4) the percentage of energy transmitted in the spark as a function of spark gap width and discharge voltage; and (5) the percentage of energy converted into the pressure wave as a function of gap width and discharge voltage. Spark-generated fractures were studied in two-and three-dimensional rock and plastic specimens. The laboratory results indicated that the pressure pulse generated by an underwater spark is a potential practical tool for rock fragmentation. The paper contains an appendix describing the capacitive pressure gage specially developed for the laboratory tests.

Jan 1, 1969

By F. D. Wang

The Bureau of Mines has developed a computer program for evaluating pit slope stability by the finite element stress analysis and limiting equilibrium method. The program includes the finite element method of stress analysis using triangular elements, finite-element model mesh generation, plotting of the model mesh and stress contours, calculation of a factor of safety along a circular or a plane failure surface, and location of a critical circular failure surface. Instructions for preparation of input data, an example problem, and the program listing are presented.

Jan 1, 1972

By Douglas Pollock, John Organiscak

Water spray characteristics, including droplet size and velocity, airborne dust capture potential, and induced airflow quantity for various spray nozzle designs were evaluated to provide basic information for improving spray applications. Water droplet size and velocity characteristics were initially measured by a Phase Doppler Particle Analyzer (PDPA) for hollow cone, full cone, flat fan, and air atomized spray nozzles at similar operating parameters. Airflow inducement and dust capture experiments were also conducted under the same operating parameters to examine any salient features of the spray nozzle type, droplet characteristics, induced airflow, and airborne dust capture. Test results indicate that there are trade offs between airflow inducement and dust capture efficiency. A spray nozzle with a wider discharge angle was observed to induce more airflow, but at reduced dust capture efficiencies. Increasing spray nozzle fluid pressure(s) generally reduced water droplet sizes with concurrent increases in droplet velocity, airflow inducement, and airborne dust capture. Placing a three-sided barrier around the spray nozzles normally reduced spray air induction and increased dust capture efficiency. A direct relationship between airborne dust capture efficiency and spray input power normalized per unit of airflow induced was ob- served. This information can be utilized to improve the performance of water sprays for reducing airborne dust levels.

By R. V. Ramani, V. T. Burgos, J. A. McClay

Introduction The Cost program was developed to provide the planning engineer with a tool to evaluate the cost implications of the technical mine design decisions. Direct costing methods are employed, where feasible, to provide greater detail and accuracy in the primary cost centers. Options have been provided in the cost computation, economic analysis, and output data subsystems to increase the flexibility of the system. Computer Program The program is written in Fortran IV for use in the IBM System 360/370 computers. i. Main - The main routine reads and stores input data from three sources, user input, Cost Data Library, and data transfer from the Master Design Simulator. Data is trans¬ferred to the appropriate subroutines, as they are called, by means of labeled common blocks. ii. Subroutine CSTCOM - is a data modification routine which computes the peripheral charges related to labor and supervisory costs. iii. Subroutine MANPWR - interrogates section data to determine the total labor and supervisory costs for each cost center. iv. Subroutine CAPCST - computes the total capital investment for each cost center, including the economic life and salvage value of each element. Capital costs are determined by user selection of quantities and models of equipment. Equipment costs are stored in the Cost Data Library for retriev-

Jan 1, 1975