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By E. D. Gardner

This paper is the third of a series of three on placer mining in the western United States. The first paper4 discusses the history of placer mining in the Western States and the production of placer gold, geology of placer deposits, location of placer claims on public lands, sampling and estimation of gold placers, and classification of placer-mining methods, together with hand-shoveling and ground-sluicing. The second papers deals with hydraulicking, sluice boxes and riffles, recovery of gold and platinum from placer concentrates, treatment of amalgam, and marketing of placer gold. The discussion of sluice boxes and subsequent subjects in the second paper applies to all forms of placer mining. The present paper treats of dredging and other forms of mechanical handling of placer gravels, and drift mining.

Jan 1, 1934

By R. D. Joseph

This report deals exclusively with roof-fall accidents that occurred during 1955 and 1956 in both anthracite and bituminous-coal mines throughout the United States. The report stems from a cooperative study conducted by the Bureau of Mines and the Roof-Control Committee of the Coal-Mining Section, National Safety Council. The study includes an analysis of individual accident reports, sets forth the measurable factors, and compares such factors with a representative sample of average data from 39 anthracite mines and 117 bituminous mines (appendixes A and B). Particular emphasis is placed on fatal roof-fall accidents with respect to their causes, locations, and the methods of support used at the point of occurrence. INTRODUCTION The purpose of the report is to classify all measurable details of the occurrences of roof-fall fatalities so that the material presented will assist those promoting safety and will serve as a manual for those whose principal duty is inspection of mines.

Jan 1, 1958

By S. M. Shelton

Ferrograde manganese ore or its equivalent is essential to the manufacture of every ton of steel produced; although it is well-known that there are largo deposits of low-grade ore in the United States, production of substantial amounts of ferrograde material from domestic sources presents a problem that becomes more and more critical as the stock piled ore is depleted through inability to obtain adequate supplies from foreign sources. Consequently, a program of laboratory and pilot-plant investigations designed to solve the problem of obtaining a domestic supply of manganese has been undertaken by the Metallurgical Division, Bureau of Mines. This paper is one of a new series that will include reports of results obtained in the various investigations conducted under the manganese program. The scope of the program and the organization that was set up to direct and supervise the work were discussed in the foreword of the first paper of this series, Report of Investigations 3506, Manganese Investigations 1. Concentration of Manganese Ores from the Drum Mountain District, Utah, by S. R. Zimmerley, J. D. Vincent, and C. H. Schack. Other reports will be published as the work progresses.

Jan 1, 1942

By Robert W. Metcalf

Corundum, natural alumina, or aluminum oxide (A1203) is the hardest mineral known except diamond. Theoretical composition is Al 52.9 percent and 0 17.1 percent, but it always contains small quantities of impurities, chiefly silica, iron, and lime. The melting point of corundum is above 1950° C., and it is insoluble in the strongest acids. Its hardness (9 on the Mohs scale) varies slightly according to purity, and its specific Gravity ranges from 3.95 to 4.10, 4 being a fair average. The index of refraction is 1.760 to 1.768 and its streak is white. Luster is adamantine to Vitreous, come specimens pearly, and color varies widely from white, gray, pink, and blue to black, brown, or bronze. Gem varieties are transparent or translucent, and of more brilliant coloring - red, blue, yellow, purple, or green. Corundum occurs in opaque massive or block structure with parting planes little developed or only roughly delineated and in granular form as minute crystals or small, irregular grains interspersed throughout the contact zones of schists and gneisses.

Jan 1, 1944

This report summarizes the results of the Narragansett Win Projec't's activities during the U.S. Bureau of Mines (BOM) Phase 1, which was transitional from and which followed the National Science Foundation (NSF) Phase which initiated the investigation of New England's potential roil resource. The 960 sq. mile basin is structural and topographic lowland containing 12,000 to 20,000 ft. of terrigenous clastic sediments of late Pennsylvanian age, and which rests on an upper Precambrian and Cambrian basement. The Rhode Island Formation, which is the coal-bearing unit, comprising the bulk of the Pennsylvanian rocks consists, in order of decreasing abundance, of sandstone, conglomerate, silts tone, shale, and coal. In the NSF Phase, 24 drill-holes yielded 17,900 ft, of core; in the BOM Phase I study, 4 drillholes yielded 2,100 ft. of core. Anthracite and semi-anthracite was encountered in beds Up to 30 ft. thick in widely spaced parts of the Basin. The coal, typically very low in sulfur, and a high ash anthracite, won mined in substantial volumes from 1808 to 1959 from shaft and open lit in Portsmouth and Cranston, R.I., and in lesser volumes in Mansfield, Mass. Currently coal is now being mined in Plainville, Mass. as a fuel in the manufacturing of light-weight aggregate from the same quarry that serves as the source of the rock being processed. The structurally complex Narragansett Basin is now known to have a greater extent than earlier since recent drilling by others (Chapter 2) has confirmed our interpretation that the Basin extended offshore south A Boston. The, Basin also extends into Rhode Island Sound to the south. The geological structure is more complex in the southern part of the Basin than in the northern part. Three episodes of folding have been documented on Aquidneck Island and four episodes of faulting have been demonstrated for the Basin as a whole. Relatively less well exposed rock in the northern part of the Basin, increases the difficulty of recognizing and correlating structural episodes in the northern part of the Basin. The Basin his hewn subdivided into six structural domains which appear to have distinctive structural, metamorphic, paleontological and sedimentological differences that mw assist in isolating important events in the evolution of the Basin and its component parts. The tentative structural model recently developed in POP Phase I has important implications for exploration and mining. In the first and second folding stages the coal is mobilized and thickened in the crests and troughs of folds whose axes are horizontal to subhorizontal. While conventional coal exploration and mining methods are not applicable, great thickening in the crests and troughs of large scale structures, which can he defined by geology, geophysics and drilling, may provide compensating advantages. Bedrock over most of the Basin is 0-50 ft., but thicknesses of glacial deposits up to 150 ft. are present locally. Pro-Pleistocene topographic trends are controlled by structure and rock hardness; Pleistocene deposits aligned to the S. F. are superimposed on earlier trends. The southern part of the Basin is mainly dominated by high grade Barrovian metamorphism and plutonism of Permian age, related to the Alleghanian Orogeny. About 300 sq. miles of the 960 sq. mile Basin has been affected. The remaining 660 sq. miles, in the chlorite and subchlorite zones of metamorphism are compatible with the presence of high quality anthracite and semi-anthracite. Illite crystallinity studies begun in the NSF Phase, have been carried out in the BOM Phase l with important results. About ME of the northern Basin is now known to be in the diagenetic (unmetamorphosed) or subchlorite zone and the remainder in the chlorite zone of metamorphism. Mite studies, probably best recording temperature effects, show a generally progressive increase from the NW corner of the Basin near Plainville, Mass. toward the south and southeast. Reflectivity and coal petrography studies, probably best recording pressure and effects related to shearing, indicate a generally opposite pattern. Thus these methods provide powerful tools for the ultimate solution of problems important to coal exploration for coals of higher combustible volatile content and exploitation of these. Due to the complex nature of the coal, chemical data may not he easily used to determine rank. The coals have been tectonically deformed and mineralized. This deformation plus thermal metamorphism have altered the coals, in some cases by producing natural coke. Brecciated coal is often coated with a secondary depositional carbon. The coals' hydroscopic nature and high ash contents are due to the deformed nature of the coal and the presence of this secondary carbon. The stratigraphy and sedimentology of the coal-bearing Rhode Island Formation is similar to described alluvial fan deposits. The non-geological studies al-low three conclusions to be made: 1. A substantial number of areas have been identified in the Narragansett Basin in which mining could be carried out without undue difficulty from a land use point of view. 2. Substantially more than two hundred instances of past or current- mining activities have been identified in the Basin. Many of those are in areas defined as geologically interesting, and may be advantageous From the point of view of future exploration. 3. The map synthesis technique developed for this contract is successful and may easily be adapted to future exploration in its current form and also in its expandable form dealing with unit measurements of one-tenth mile. We recommend that BOM Phase 2 exploration should accomplish the intent of the Congressional language in House Report No. 95-1251, to continue a substantial drilling and geophysics program: "The Committee expects the Bureau to continue studies involved in ascertaining the extent and quality of low sulfur coal reserves in the Narragansett Basin in New England including necessary drilling and geophysical studies. The knowledge of the extent of such deposits is of great importance to this 'energy pour' area".

Jan 1, 1979

By Alfred Wild

The Kraftile Co. plant, Fremont, Alameda County, Calif.--the largest producer of glazed, structural wall units west of the Rocky Mountains--maintains modern processing facilities to evaluate and blend a wide variety of clays from several sources to produce quality products. The report desribes the prospecting, exploration, and test methods used to locate raw material sources and covers processing methods, cost factors, and trends. Also, the geologic and ceramic factors are considered in a general discussion of the economics, potentials, and requirements of clays as raw materials for ceramic tile manufacturing.

Jan 1, 1963

By H. P. Greenwald, H. C. Howarth

There was reported in Bureau of Mines Technical Paper 5754/ a series of tests to determine the compressibility and bearing strength of specimens prepared from blocks of potash salt obtained from a mine near Carlsbad , N. Mex . The events leading up to the investigation were sketched in a foreword by George S. Rice , then chief mining engineer of the Bureau ( retired September 30 , 1937 ) ; this foreword also gives a discussion of the possibility of increasing the ultimate total recovery of the potash salt by " second mining" of pillars or by use of a longwall system . In June 1936 , Rice and the senior author visited Carlsbad with H. I. Smith , chief of the mining division of the Geological Survey , to observe mining then in progress and to discuss with the management of one of the mines records of convergence of roof and floor which they were obtaining . It developed that serious thought was being given to the possibility of roof failure resulting from shear at the faces of pillars . There was envisioned the danger of such cracks extending upward to water - bearing strata . Obviously , the simple compression tests of the potash salt then being made would throw no light on this question , and tests of assemblies of potash and roof salts would have to be made . In this connection it is to be remembered that in the mine no sharp division exists between the potash salt being recovered and the nearly pure halite which forms the roof . The interlocked crystalline structure is continuous , and there is merely a very rapid decrease in the proportion of sylvite in a short distance vertically . Figure 2 of Technical Paper 575 shows that two samples near the top of the salt being mined contained , respectively , 51 and 65 percent potassium chloride . Contrasted with this is an analysis of the roof salt given on page 24 of that publication , which showed only 3.6 percent potassium chloride . As the data given in Technical Paper 575 show , the roof salt is much less plastic than the potash salt . The immediate roof may then be thought of as a more rigid stratum of indefinite extent resting on and continuous with yielding supports and loaded uniformly at the rate of 900 to 950 pounds per square inch . Just what thickness of the salt should be considered as immediate roof is uncertain .

Feb 1, 1938

By W. D. Kaiser

Recent legislation and expected future legislation is aimed at reducing the dust levels developed in underground coal mines. Several techniques for reducing dust levels are being evaluated. One of these is the modification of cutting parameters such as feed rates, cutting speeds, and pick configurations in order to reduce the amount of dust generated. In order to evaluate the feasibility of modifying cutting parameters to reduce dust, the Bureau of Mines commissioned Battelle to construct a small scale mining machine which could be used for evaluating the effects of those changes in cutting parameters. Specific features of this machine were that it should be highly instrumented to measure various cutting parameters, should have a wide range of feed and speed controls, and it should be possible to vary the pick configurations and geometries on the machine. In addition, it was desired that this machine should have cutting capabilities which greatly exceed present coal mining practice and also that the unit should be small enough and portable enough that it could be taken into and out of operating coal mines with a minimum of interference with the normal coal mine operations. The first step in constructing a machine to meet these requirements was to determine the cutting forces and approximate sizes of components which would be required to cut at the speeds and feeds specified by the Bureau of Mines. Initial calculations using; published data on cutting forces indicated that cutting forces in the neighborhood of 5,000 lbs and power levels of approximately 30 horsepower would be adequate for the application. However, further data developed during the course of the project indicated that when low efficiency picks are used, cutting forces and powers can be two to three times as high as these initially estimated values. After several design iterations, a design was chosen in which the cutting head was driven by four hydraulic motors which were part of a hydrostatic transmission which, in turn,

Jan 1, 1973

By Alvin Kaufman

To aid industry and Government in planning water developments the Bureau of Mines in 1963 canvassed mineral producers to determine water use in 1962. Water use by the mineral industry comprises only 2 percent of the water withdrawn by industry as a whole. The major water-using mineral industries are natural gas processing, phosphate rock, sand and gravel, and iron ore. Analysis indicated the following conclusions: 1. Total water use and new water intake is dependent on the quantity of material processed and the process water requirements of the particular industry or commodity. 2. Recirculation is dependent on the processing requirements of a particular commodity, the manner in which the water is used, cooling and condensing requirements in certain large industries, the quality of new water intake, and the need to treat new and discharged water. 3. Consumed water is dependent on the quantity of water recirculated, the temperature and humidity in the area, and the proportion of water used for cooling and condensing. 4. A threefold increase in water use by the mineral industry by 1985 is forecast

Jan 1, 1966

By J. L. Konchesky

In gasifying pulverized coal with steam and oxygen, the particle size of the coal fed to a gasifier should be as small as economically possible. A potential way to achieve this advantage is to reduce the particle size of the coal by passing the coal-steam mixture at high velocity through a heated tube coil before the mixture enters the gasifier. To evaluate this method the Federal Bureau of Mines flashed coal-water slurries in externally heated metallic tube coils to determine the extent of size reduction. The first of two different laboratory-scale apparatus reduced the average particle diameter of subbituminous C coal from 190 to 110 microns at an outlet velocity of 330 feet per second (f.p.s.). At the same outlet velocity, a second apparatus reduced the average particle diameter from 250 to 140 microns. An increase in velocity produced more finely divided coal, but variation in temperature and pressure had no effect except as they affected velocity. Virtually the same size reduction was noted for five ranks of coal at equal velocities. The rate of increase in particle-size reduction with increase in velocity decreased with a decrease in particle size. The pulverizing mechanism was concluded to be abrasion of the particles with each other and with the tube wall.

Jan 1, 1961

By Christopher Mark

The first International Conference on Ground Control in Mining opened with the topic of pillar design. Two classic papers were presented, one by Bieniwski and the other by Wilson. Unfortunately, the two methods were so radically different from each other that it was nearly impossible to reconcile them. Adding to the confusion were the many other pillar strength formulas (such as the Salamon-Munro, the Holland-Gaddy, and the Obert-Duvall, just to name a few) that were also available. Little wonder that discussions of pillar design in those days often ended with anguished cries of “but which formula is the right one?” The past 25 years have seen substantial progress in the science of coal pillar design. Indeed, one testament to the improvement is the relative scarcity of papers on the topic at recent Conferences. Two factors have been largely responsible for the progress that has been made. The first has been the collection of large data bases of actual case histories of pillar performance in a variety of settings, from shallow room-and-pillar mines through deep cover longwalls. These have made possible the development of empirical design procedures that are closely linked to real world experience. The second important factor is the development of sophisticated computer models that can accurately simulate pillar behavior and roof/pillar/floor interactions. Together, these two lines of research have led to a new understanding of pillar mechanics that identifies three modes of pillar failure: • Sudden, massive collapse, accompanied by airblast, for slender pillars (width/height<4) • Squeezing, or slow, non-violent failure, for most room and pillar applications (4<w/h<10) • Entry failure or bumps for deep cover and longwall applications (w/h>10) It is particularly satisfying that the insights gained from numerical models broadly support those obtained from the empirical studies. While far less controversial than in the past, pillar design problems continue to arise. One recent example is pillar design for highwall mining. NIOSH has just released a software package, called ARMPS-HWM, which employs a number of modern pillar design concepts. Since highwall mining web pillars are long and slender, the greatest danger is that of a sudden collapse. ARMPS-HWM suggests two possible prevention strategies, one which

By D. Ng

A facility to evaluate the fire endurance of mine stoppings was constructed by the Bureau of Mines in the multiple entry section of the Bruceton (PA) Experimental Mine. Stoppings up to 6 by 18 ft can be tested in a manner simulating mine conditions. The stopping is subjected to a 70-min liquid fuel tray fire with an energy output of 75,000 Btu/min. The stopping and adjacent areas are instrumented with thermocouples and heat flux gauges. Data acquisition is by an automatic data logger capable of continuously recording over 100 channels of information. Two 8-in-thick concrete block stoppings and a galvanized steel stopping were tested. A crack developed on the fire side surface of the block stoppings where the flames were most intense. However, the temperatures of the unexposed surfaces of the stoppings never exceeded 800 C and the surfaces were undamaged. The steel stopping retained its structural integrity during the test. The temperature of the unexposed steel surface reached 5000 C, but combustible materials located 1 ft from the surface did not ignite. A 3/4-in-thick coating of construction plaster was applied to the fire side of the previously tested uncoated steel stopping. The quantity of heat energy transmitted across this coated metal stopping was reduced approximately 50%. All stoppings prevented the passage of flame and smoke.

Jan 1, 1988

By Rodney D. Rosenkranz

Energy consumption in domes tic copper production has increased nearly 60 percent in the last 10 years, reaching approximately 175 trillion Btu in 1973. Energy required to produce 1 pound of copper rose from nearly 41,000 Btu in 1963 to nearly 50,000 Btu in 1973. Production from lower grade ores and strict pollution control regulations have contributed to this increase. Each stage of copper production has been analyzed to determine total energy consumed, energy mix required, cost of the energy, and recent or proposed changes in operations which may affect the consumption of energy by the copper industry. Data have been gathered from a recent Bureau of Mines canvass of the industry, from visits to copper operations, and from conversations with copper industry officials.

Jan 1, 1976

By Lawrence J. Froisland

To aid in minimizing adverse environmental impacts of mining and mineral processing, the Bureau of Mines studied changes in soil characteristics in topsoil stockpiled during mining operations. Topsoil stockpiles in arid areas of New Mexico, Utah, and Wyoming were sampled over a 1- to 8-yr period to determine any changes in physical, chemical, or biological parameters in the top 15 ft of soil. Parameters examined in this study included soil moisture, pH, electrical conductivity, and cation exchange capacity; total nitrogen, organic carbon, carbon to nitrogen ratio, extractable potassium, and soluble phosphorus levels in the soil; general levels of bacteria activity in the soil; and productivity of the soil as measured by shoot yield in growth tests. Data were analyzed by multiple linear regression to determine possible effects of stockpile age and depth. Bacteria population counts, used as an indicator of goner l bacterial activity, was the only parameter found to be significantly correlated with stockpile age and depth at more than one site. Bacterial activity increased with depth at the two sites where it was measured. Activity increased with age at one site and decreased with age at the second. Significant changes in soil pH, electrical conductivity, and moisture were significantly correlated with stockpile age and depth at single sites. This study did not show significant, consistent deterioration in soil characteristics or growth yield of topsoil stored in stockpiles.

Jan 1, 1987

Operator efficiency and control capability along with cost effectiveness have been the quest of mining, industrial, and mobile hydraulic engineers for years. The majority of the functions in present day fluid power systems are controlled by on/off control valves. They are inexpensive and provide easy installation and operation, but they lack the quality of fine control of load flow or what is sometimes known as "feathering the load". An alternate approach to obtaining this capability is the use of electro-hydraulic servo-valves, but their implementation into a system is complex, and they are expensive. As a result, electrohydraulic systems are still used primarily in the aerospace industry. Of late, a compromise seems to have evolved between the on/ off control systems and the servo-technology is the so-called proportional flow control valves. A proportional flow control valve meters fluid to the load in proportion to the input command from the operator. In principle, it is similar to a conventional flow control valve and is tailored to meet the control requirements from the load point of view. The hydraulic system using this valve usually works in an open-loop mode with the operator closing the loop. Incorporating load-sensing mechanisms and adoption of electrical/electronic signalling into the valve make it the "ideal valve" which designers have been looking for from a techno-economic point of view.

Jan 1, 1983

By George A. Costello

A theoretical analysis is presented for the static and dynamic response of wire rope in deep-shaft mining operations. Expressions for the stresses in the individual wires of complex wire ropes are derived, and specific results for simple strands, 7x7 ropes, 6x 19 Seale ropes both with and without internal-wire-rope cores, and 6x25 filler-wire ropes both with and without internal-wire-rope cores, are presented for the case of ropes subjected to a combination of axial loading and bending over a sheave. Consideration is also given to the dynamic overloading associated with certain mining operations, such as dumping ore into a suspended skip and accelerating a fully loaded skip upward. Experiments to determine the axial stiffness of wire rope are described. Factors affecting the service life of wire rope, such as residual stresses, contact stresses, and fatigue behavior, are discussed. Specific research areas in need of further investigation are identified.

Jan 1, 1983

By R. L. Rickel

The Bureau of Mines, as part of its minerals environmental technology research, conducted a study of mine waste tailings disposal. Part of the investigation evaluated the sand bed dewatering technique for disposal of alumina mini plant tailings as a means to increase consolidation rates and contain effluents. The technique employs a bed of sand resting on an impervious bottom. The tailings slurry is impounded over the sand layer and is dewatered through bottom drain piping. The study employed a single 10-ft-high, 6-in-diam, clear polyvinyl-chloride (PVC) column, and thickener wastes from the acid leaching of calcined kaolin clay. Results showed a consolidation rate of 41 in in 186 days for a total volume reduction of 37 pct. Sand bed dewatering was an efficient technique for solid consolidation and effluent containment when compared with data obtained from other dewatering studies.

Jan 1, 1982

By Anthony T. Xannacchione, Luis E. Vallejo

At present, there is little knowledge concerning the shear strength of clays containing floating rock particles with concentrations from 0 to 30%. In practice, the effect of rock particles is typically disregarded in shear strength analysis The two primary reasons for this are: 1) a lack of agreement concerning the influence of rock particles on material strength, and 2) the expense and difficulty of testing day-rack mixtures with existing laboratory procedures. These factors have impeded the development of successful slope remediation design techniques far colluviums derived from resistant sedimentary rocks or spoil produced from surface mining. This study reviewed 3 1 technical papers which contain analysis of shear strengths for clay and sands with varying mixtures of rock particles. These technical papers, published over the last 40 years, are comprised of field case studies, laboratory evaluations, and theoretical analysis. Evaluation of this body of knowledge ha shown that the shear strength gradually increases with increasing percentages of floating particles in unsaturated clays.

By Stephen R. Iverson

Manganese deposits exist in the Wonder Mountain RARE II area (fig. 1). The manganese mineral is primarily bementite, a silicate. It occurs with Jasper and manganese oxides in tabular or irregular lenses along the contact between red limestone and basalt. There are about 11,000 tons (10,000 t) of indicated sub-economic resources in the northeast part of the study area. Of this, 10,700 tons containing 27.1 percent manganese is at the Apex Prospect and 300 tons averaging 24.8 percent is at the Brown Mule Mine (fig. 1). Another 1,000 tons (900 t) containing 27.0 percent manganese is at the Steel Creek deposit 0.5 mi (0.8 km) west of the area (Wiebelt, 1942, p. 1, 2). Each of these deposits is subeconomic due to small tonnage and high estimated recovery costs. They are in a regional belt of manganese occurrences trending northwesterly through the area. Pardee (1921) reports that manganese ore was shipped from the Triple Trip (Brown Mule) Mine in 1916.

Jan 1, 1982

By K. L. Paciorek

Organic materials utilized as cable Jacketing, cable insulation, standoffs, insulating boards and potting compositions were identified and d literature survey performed to obtain the required thermal oxidative and moist tracking data. Thirty representative compositions were procured and subjected to thermal and moist tracking evaluations. Tracking was found to invariably result in ignition or glow of the test specimen. Influence of parameters such as electrolyte strength and composition, temperature, conductor spacing, and electrode material were investigated. Volatile s produced by selected insulators on thermal oxidative and electrical stress were identified, quantitated, and their potential impairment action upon a current interrupter assessed.

Jan 1, 1980