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By E. S. Leaver

The gold that is not recovered by a particular process is refractory to that process. A study to determine how the refractory gold is associated in the ore constituents usually indicates the needed improvement in the process or additional methods for bettering recovery. In preliminary work, segregation of the various minerals, gangue or impurities, and data showing the reactions of each in the recovery method readily confines the refractory gold to a certain part on which extensive research can be directed. In this dissecting plan, the microscope is an important aid in locating the refractory gold but should be supplemented by chemical tests. Each ore is an individual problem until the association of the gold has been determined. Knowing the problem through the interfering minerals or elements, the solution often is only the application of part of a former known practice as an auxiliary or additional feature. In the treatment plan for most gold ores, it has been the custom to try each of the usual recovery methods or combinations thereof, accepting the best results on a basis of the lowest cost. A better plan includes knowledge of the association of the gold and the various minerals from which it is to be recovered. This presents reasonable foresight into the problems that should be expected and permits some provision for avoiding probable difficulties. The preliminary work should include: Determination of the percentage of free gold with classification showing size of gold particles to be expected; determination of the percentage of gold associated with each mineral and whether it be freed from the mineral by crushing; and an analysis of representative samples of the ore to include other valuable minerals and the form in which they occur.

Jan 1, 1934

By M. L. Bowser

Pulse-forming circuitry is described for use in explosives research that requires precise synchronization and control of events in order to investigate detonation parameters. Included are pulse generators for oscilloscope sweep control, counterchronograph actuators, and a raster-type oscillographic method for the determination of velocities of detonation that are applicable to studies on solid, liquid, and gaseous detonations. INTRODUCTION Prom time to time, requests have been received for information on electronic circuitry used in explosives work at the Explosives Research Laboratory, Bruceton, Pa. The methods used are not entirely original;4 5 6 however, modifications of earlier techniques and some novel design aspects have resulted in time-tested methods that warrant a more detailed description.

Jan 1, 1962

By R. S. Dean

The development of metallurgical processes may be divided into periods : First , the discovery of a basic reaction which brings about the production of the desired product from the available raw material ; second , a long stage of mechanical development during which little or no attention is paid to the reaction itself ; and third , a careful study of the reaction . Most metallurgical processes are to -day approaching the end of the second period . This we may illustrate by the steel process . The reaction of carbon with iron ore to produce pig iron and the subsequent refinement of the pig iron by an oxidation reaction is very old . Development in modern times has been almost entirely mechanical , the development of the blast furnace , furnace , the Bessemer process , the Siemens process , and even the Aston process for wrought iron being mechanical improvements almost entirely . Metallurgy is now entering a phase where the reactions are being considered . The question of how far can they be made to proceed is being repeatedly asked . As mechanical processes are improved , we approach a limit to which our basic reactions can be pushed which is determined by the nature of the reactions themselves . We want to know : How far can iron be decarbonized by iron oxide ? How low can the oxygen of copper be reduced by any given reaction? How efficiently can the fuel in a zinc reduction process be used ? The demand for purer metals and lower production costs has forced these and similar questions upon us . How are we to answer them ? The determination of these equilibria or end points of metallurgical reactions by direct means is fraught with difficulty because here we must overcome mechanical difficulties which too often become the limiting factors even in the laboratory and we do nottherefore get the actual limit to which the reaction itself may be carried . Further , there are so many reactions of metallurgical materials that to survey each separately is a job to give pause to any experimenter or group of experimenters .

Dec 1, 1930

By E. C. Lane

This paper is the second report of the results of the United States Bureau of Mines twenty-third semiannual survey of motor fuel marketed in the United States. The first paper, reporting data relating to gravity, vapor pressure, and distillation range of the samples, was published as Report of Investigations 31293. A third and concluding paper giving the results of other tests will be published as soon as these tests have been completed. The present paper deals with the data of the twenty-third semiannual survey presented in accordance with the revised specifications for United States Government motor gasoline. The sample numbers used are identical with those used in Report of Investigations 3129, with additional data included for copper strip corrosion (method 530.22),4 and sulphur content by the lamp method. Three hundred and twelve samples were collected and analyzed in this survey. Two hundred and seven samples were competitive-price gasolines and one hundred and five samples were premium-price motor fuels.

Jan 1, 1931

By J. W. Paul

This circular is one of a series of papers4 on coal-mining methods and costs which are being prepared through the sponsorship of the U. S. Bureau of Mines for the purpose of presenting information on present mining methods and certain features which govern costs, safety, and conservation. The methods employed are influenced by natural local conditions with respect to the thickness, character, and dip of the coal bed, the nature of the roof and thickness of the overbearing strata, and the means employed for roof support and its control.

Jan 1, 1929

By G. S. McCaa

Rock-dusting is an. effective means of preventing coal-dust from propagating an explosion in a coal mine, but it will not prevent gas from igniting-explosively and with much attendant damage locally. Ventilation must therefore be effective at all times, regardless of the employment of other explosion-prevention methods, if gas explosions are to be avoided. This paper describes a gas explosion which occurred in as bituminous mine that was well rock-dusted at the point of ignition and which exemplifies the value of rock-dusting, the necessity of maintaining effective ventilation, and the need of permissible rock-dusting machines receiving power from a permissible locomotive. Description of Explosion The mine in which this explosion occurred is developed on a panel system in a practically level seam; the panel entries are driven in pairs, and the air current intakes on the right entry and returns on the left entry. Near the mouth of the intake a door is placed to control the ventilation; board stoppings are placed in crosscuts, except the second from the face, in which a brattice cloth curtain is hung, the last crosscut is left open and line brattices conduct the air current from the last crosscut to the faces. In No. 7 entry the last cross-cut was 152 feet from the face, the line brattice being within 38 feet of this face, and the second crosscut was 250 feet outby the face of the back entry or return. Seven days prior to the explosion the intake and return entries were rock-dusted to within 38 feet of the face, and as the entry had advanced during the week, the rock-dusting was to be extended.

Jan 1, 1929

By R. K. Conrad

The Bureau of Mines conducted corrosion research to determine suitable construction materials for geothermal resource recovery plants. Weight loss, pitting and crevice corrosion, U-bend stress corrosion, and electrochemical polarization measurements were made on selected metals in brine and steam process environments produced from high-enthalpy hypersaline brine from geothermal well Magmamax No. 1 at the Salton Sea Known Geothermal Resources Area, Imperial Valley, Calif. Cadmium (and by extension cadmium coatings) and a 6061-T6 aluminum alloy were unsatisfactory because of high general corrosion rates and, in the case of aluminum, severe pitting Molybdenum and niobium (columbium) were resistant to general corrosion, pitting, and crevice corrosion, Copper alloys corroded at rates that may preclude their use in wellhead brine, The presence of iron accelerated the corrosion of the copper alloys Titanium alloys were resistant to general corrosion and stress corrosion cracking in all of the environments. They exhibited crevice corrosion in some of the brine and steam environments and Ti6A14V pitted in the brine environments. They exhibited passive behavior over a broad range of potentials. Exposure tests were conducted on a high-temperature polyphenylene sulfide thermoplastic (Ryton) in the same environments. A 40-pct-graphite fiber-reinforced Ryton composite deteriorated readily in wellhead brine and failed in all of the brine and steam process environments; Ryton coatings on 316L stainless steel were adherent and performed well.

Jan 1, 1983

By J. B. Zadra, J. M. Gomes, Don H. Baker

Electrolytic deposition at 1,000 ° C in an electrolyte essentially consisting of 7 parts sodium pyrophosphate , 2 parts sodium chloride , and 1 part sodium tetraborate yielded tungsten of 99.9 percent purity . Scheelite concentrates containing 25 to 73 percent WO, and varying quantities of iron , lime , and silica were used as feed materials for the electrolysis . The metal contained less than 0.01 weight - percent each of iron , calcium , silicon , aluminum , carbon , and oxygen . Modification of the electrolyte permitted deposition of equal - quality metal from scheelite concentrates containing higher quantities of iron , calcium , and silica . The electrolytic separation of molybdenum and tungsten was accomplished by minor variations in the operating procedures .

Jan 1, 1964

By D. E. Shanks

The Bureau of Mines surveyed a variety of inorganic ion-exchange materials to determine their suitability for removing valuable accessory elements and troublesome contaminants from metallurgical process and waste streams. Most of the materials, which included molecular sieves, heteropolyacid salts, and hydrous metal oxides, did not give adequate separations, did not have the necessary stability in strong acids or bases, or were not in a physical form suitable for ion-exchange use. Many of the suitable inorganic materials, especially the hydrous oxides, were capable of cation exchange with high capacity only in basic conditions, which caused hydrolysis of most of the cations tested. Multivalent anions, such as arsenate and phosphate, were easily removed from acidic solutions by hydrous oxides. Hydrous zirconia was the best material for this purpose. Multivalent anions were not easily des orbed because of compound formation; therefore, conventional ion-exchange techniques could not be employed. As an alternative approach, hydrous ferric hydroxide was used as a filter material to remove arsenate and phosphate from acid solutions. One gram of arsenic was removed from solution for each 20 g of ferric hydroxide. Ferric hydroxide is preferable to hydrous zirconia for use as a filter material because of low cost.

Jan 1, 1983

By Paul S. Schopf

The results of an experimental investigation into the possible use of medium energy acoustic fields (130 to 140 dB) to precipitate 1 to 10 micron particles is presented. The aerosol was produced with a LeMer generator using oleic acid and nitrogen. The sound field was a sinusoidal standing wave field in an acrylic tube, with light transmission data used for concentration determination. The results showed collection efficiencies of up to 80% on 2 micron particles with a residence time of 11.8 seconds at a sound pressure level of 139 dB re 2x10-5 N/m2. A discussion of the possible turbulent mechanism is made, as well as review and comparison with others? work.

Jan 1, 1972

By R. H. Bedford

"The El Dorado copper mine is situated in the foothill copper-zinc belt of California, which traverses the western slope of the Sierra Nevada with unusual persistence from Butte County to Kern County, a distance of more than 300 miles. Although this area contains such important past producers as the Penn mine, Union, and others, a great part of the current production has been derived from smaller properties, which depend largely on premium metal prices for economical operation. The El Dorado mine is in the latter group, which constitutes an important source of metal in a national emergency.Exploration by the Bureau of Mines by means of eight diamond-drill holes Indicated narrow, intermittent lenses of copper ore along structures boo feet in length. The copper occurs in massive sulfides composed of chalcopyrite, pyrite, pyrrhotite, and minor quantities of bernite. The sulfides have evidently replaced tuffs, which are interbedded with the Mariposa slates and shales.H. A. Weiler and Hal T. Hall, owners of the El Dorado copper property, requested an examination by the Bureau during the latter part of 1914. In December of that year an engineer of the Bureau of Mines visited the mine and recommended the project work undertaken. The purpose was to aid the owners in bringing the property into production of copper and zinc, which at that time was critically essential to the war industries.Complete factual data obtained by the exploration are embodied in this report.In its program of exploration of mineral deposits, the Bureau of Mines has as its primary objective the more effective utilization of our mineral resources to the end that they make the greatest possible contribution to national security and economy. It is the policy of the Bureau to publish the facts developed by each exploratory project as soon as practicable after its conclusion. The Mining Branch, Lowell B. Moon, chief, conducts preliminary examinations, performs the actual exploratory work, and prepares the final report. The Metallurgical Branch, R. G, Knickerbocker, chief, analyzes samples and performs beneficiation tests. Both these branches are under the supervision of Dr. R. S. Dean, assistant director.Acknowledgment is made to A. O. Johnson, chief, Reno Division, Mining Branch, and Lowell B. Moon, chief, Mining Branch, for their aid and direction."

Jun 1, 1946

By J. E. Geier

This Bureau of Mines report reviews hypotheses for the mechanism by which water jets reduce the specific energy of cutting for drag bits. Several of these hypotheses are shown to be inconsistent with published evidence and new observations. The notion of a limiting cutting speed, above which water jets would be incapable of rendering assistance, is shown to be improbable. The hypothesis that seems most plausible is that specific energy reductions are mainly due to the erosion of crushed materials from in front of the bit. This hypothesis leads to a prediction that, for a given rock type and jet-bit configuration at a constant depth of cut, the reduction in bit forces should be a function of dM/dx, the jet energy spent per unit length of cut. This dependence upon dW/dx is shown to be consistent with other workers? results.

Jan 1, 1987

By J. Fletcher Smoak

The value of abrasive materials consumed in the United States increased 37% in value over that of 1983 to $439 million; of which, 58% was manufactured abrasives, 36% was industrial diamond (natural and synthetic), and 6% was natural abrasives. Production value of natural abrasives, which consist of crude tripoli, special silica stone, garnet, and emery, increased 4% Production of crude tripoli, a finely disintegrated chert, increased 12% in quantity and 8% in value. Shipments of processed tripoli increased only 3% in quantity but increased 16% in value, with large increases occurring in both major end-use categories. Production of garnet, an abundant iron-aluminum silicate, decreased slightly in quantity and value after posting continued increases in quantity and value since 1980. There was a significant decrease in the quantity and [ ]

Jan 1, 1985

By G. W. Grove

The Joseph A. Holmes Safety Association acid the Holmes Association have fostered many chapters that have served as a medium in increasing safety in the mining industry. Details relating to the formation, operation, and achievements of the J. J. Forbes District. Council of the Holmes Safety Association, which operates in the Uniontown-Brownsville bituminous coal district of western Pennsylvania will be of interest to all who are striving to increase safety in mines, quarries, and in the oil fields. The Joseph A. Holmes Safety Association The Joseph A. Holmes, Safety Association' was organized in 1916 by 24 of the leading technical societies and mining organizations to perpetuate 'the memory of Dr. Joseph Austin Holmes, first Director of the United States Bureau of Mines.

Jan 1, 1929

By Vibration Research Group, Natasha K. Lee Shee, Tammy R. Eger, James P. Dickey, Paul-Émile Boileau, Lana M. Trick, Michele L. Oliver

Introduction Industrial exposure to whole-body vibration is associated with injury and discomfort. Certain industries, notably mining, construction, and forestry, involve complex 6 degrees of freedom vibration. Laboratory-based studies of vibration are essential for controlled and systematic evaluation of the human responses to vibration2. The purpose of this pilot study was to evaluate whether the duration of the vibration exposure, and rest between vibrations, significantly influence the subjective ratings of comfort during laboratory-based studies of vibration. Methods Subjects: The cumulative vibration dose was calculated, and was below the health guidance caution zone recommended by International standards3. The experimental procedures were approved by the University of Guelph Research Ethics Board. Ten adult subjects participated in this pilot experiment. All subjects completed the entire experimental paradigm; no subjects complained of pain during or after the experiment. Experimental Design: The experiment consisted of four blocks of vibration exposures; either 15 or 20 seconds of vibration (1 df:Z axis, 3 df:XY plane, 3df:YZ plane, or 6 df) alternating with either 5 or 10 seconds rest. The order of presentation of the four blocks was randomized. Each of the blocks was composed of 37 individual sinusoidal vibration exposures in randomized sequence. This abstract focused on ten identical trials, (6.3 Hz vertical vibration, 0.55 m/s2 RMS) interspersed within each block, in order to assess whether the subjects’ comfort ratings systematically varied between the 15 or 20 vibration exposures, the 5 or 10 second rest between vibrations, or within each block. The experiment involved 43 minutes of vibration within the 62 minute experiment. Vibration Apparatus: A commercial parallel robotic platform was used to apply the specific vibration exposures (R2000, Parallel Robotics Systems Corporation, Hampton, New Hampshire). The subjects sat on a passenger seat from a 1992 Honda Accord that was rigidly mounted to the robotic platform (Figure 1). This robotic system performed the specific vibration exposures operating under closed-loop displacement control. A custom-written Matlab program automated the testing sequence.

Jan 6, 2006

By Jeffrey M. Listak

The Bureau of Mines has conducted a rock mechanics study to monitor deformation of near-seam strata above a longwall panel in the Pittsburgh Coalbed. The primary goal was to determine the height of caving immediately behind advancing longwall face supports. This study, although site specific, provides information on the caving mechanism associated with longwall extractions so that strata behavior and its interaction with longwall face supports can be better understood. Two holes were drilled, approximately 550 ft apart along the center line of a longwall panel, from the surface to the coalbed approximately 650 ft below. Various downhole geotechnical instruments were used to monitor strata deformation. In addition, surface elevation surveys were conducted to differentiate between surface and subsurface activity. This report discusses the caving characteristics of the strata as the longwall panel approached and passed beneath the boreholes. Physical property data are also presented to demonstrate the relationship between caving behavior and local geology. Data show that immediate caving of strata above the longwall face occurred at a height less than 23.5 ft and that strata behavior above longwall extractions is highly dependent upon lithology, with major disturbances occurring at weak lithologic zones.

Jan 1, 1986

By Robert Lee Stahl

Comprehensive field tests were made in the Gas Hills, Wyo., to determine whether surface geophysical techniques could be used to detect and delineate faults in marginal uranium deposits. The tests were made on property owned by Federal American Partners, Gas Hills, Wyo., and included seismic refraction, self-potential, induced polarization, magnetometer, electrical resistivity, airborne infrared thermal scanning, and airborne photography. Of the several geophysical techniques tested in the field, horizontal resistivity profiling with electrode spacings in the range of 25 to 50 feet was most diagnostic of faults. The method is quick, cheap, accurate, and one that can be easily used by personnel employed by mining companies to detect and delineate faults.

Jan 1, 1973

By Árpád B. Palotás, Adel F. Sarofim, John B. Vander Sande, Lenore Rainey Christian, J. Feldermann

"Interest in the fine structure of soots and carbon blacks is motivated by a variety of possible applications. The structure provides information on the origins of the particles and on their adsorptive and reactive properties. This paper describes a method for quantification of the structure of soots and carbon blacks based on direct electron microscopic observation followed by image analysis of these materials. High-resolution transmission electron microscopy (HRTEM) provides a very detailed observation of particle structure. The differences in soot structure, because of its complexity, may not be easily quantifiable with the human eye; therefore, high-level computer software has been used to manipulate HRTEM images. This technique involves the application of fast Fourier transforms (FFT) to single particles and the measurement of characteristic parameters such as interplanar spacings and crystallite sizes from these particles. The methodology and application of this characterization technique are presented here. Results are shown for dif¬ferent samples obtained from soot and carbon black particles selected to illustrate the capabilities of the methodology. Quantitative information can be obtained on structural characteristics, e.g., interplanar spacing, circularity, orientation, elongation, and length distribution of lattice fringes, as well as on the fractional coverage of the extracted pattern. c 1996 Wiley-Liss, Inc.This paper presents a combination of techniques for recognizing and classifying different carbonaceous materials, using their structural morphology. A new method to assess and quantify the parameters which define such structures is proposed and discussed. The technique is based on the use of HRTEM (high-resolution transmission electron microscopy) and computational image analysis.It is well-known that carbonaceous materials like graphite, soots, coals, cokes, chars, etc. possess characteristic structural appearances which can vary from mostly random or amorphous to a perfectly ordered graphitic crystalline structure (Buseck and Bo-Jun, 1985; Buseck et al., 1987). The carbon structure has been variously described as turbostratic (Oberlin, 1989) or as crumpled sheets (Rouzaud et al., 1991) to indicate that parallel layering, reminiscent of graphite, is observed over dimensions of nanometers, but that these planes or crystallites show disorder over larger scales. The degree of order of such structures is strongly dependent on the thermal treatment of the material as well as on the composition of the source of the carbonaceous material. The value of the electron microscope in studying the morphology of such materials has been well-established, and abundant information is available (Ishiguro et al., 1991; Lahaye and Prado, 1978; Buseck, 1992).The use of HRTEM has brought further insight into this matter. Qualitative assessment of the structural order of such materials has been attempted over a long period of time in order to differentiate between various sources or treatments. There is, to date, no successful method available for quantifying the structural characteristics of various carbonaceous materials. This paper presents a technique which is able to recognize dif-ferent materials and to quantify the structural parameters of those materials using HRTEM and computational image analysis, including pattern recognition techniques.In the case of perfectly ordered graphitic crystals, electron diffraction is widely used for obtaining details on structure. Analysis of diffraction patterns can reveal parameters such as interplanar spacing, d002, crystallite size along the c-axis, Lc, crystal size in the plane of the layers, L., mean number of crystallites, Nc, etc.Complicated electron microscopy methods such as defocusing, tilted illumination, axial illumination, etc., often have to be used in order to characterize complex materials such as randomly oriented crystals in soots and carbons. Obtaining the right fo"

Jan 1, 1998

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.

The Ringelmann Smoke Chart fulfills an important need in smoke abatement work and in certain problems in the combustion of fuels. A knowledge of its history and method of preparation is, therefore, of interest to many. Since instructions on its use are not shown on the recent edition of the chart, those included in this revision of the previous Bureau of Mines publication now are a necessary complement to the chart, More detail regarding the use of the chart is included than was given in the earlier version.

Jan 1, 1967