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[In selecting deposits for exploration projects, tabular deposits or large mineralized masses are favored because they may be explored systematically and because they afford the best opportunity for blocking out reserves in advance of mining whereas irregular, small pipes and scattered]

Jan 1, 1941

By J. C. Franklin

The Bureau of Mines substantially reduced shale degradation in a coal mine by two spray coat applications of a water-base epoxy sealant. More than 12,700 square feet of passageways were treated, and in 18 months only one failure occurred. This failure was due to improper spray application, Material costs averaged 13 cents per square foot, and labor costs were 7 cents per square foot. Labor included moving all materials into the mine, the setup time for each of the areas coated, and application of coatings.

Jan 1, 1977

This report, the second in an annual series, summarizes information on latest technological developments and advances, and identifies trends in mining and metallurgy based on a review of activities in the minerals industry in 1971. Exploration and mining data obtained from an annual canvass are presented for 1971 and are compared with similar data obtained over the past decade.

Jan 1, 1973

By L. E. Dalverny

This Bureau of Mines report describes the deployment, 5-month operation, and lessons gained from a continuous gas monitoring system using sampling-tube bundles at an underground mine fire in West Virginia. Research information gained indicates the utility of relating certain gas concentration ratios to events during fire development, mine reventilation, and mine recovery. In addition to monitoring the quality of remote fly ash seals, the system provided timely warning of dangerous gas concentrations which developed during surface and underground recovery activities. An evaluation of system components is supplemented by recommendations for improvements.

Jan 1, 1975

By L. J. Froisland

Water classification and heavy-media sink-float methods were investigated for concentrating metallic junk automobile shredder rejects initially upgraded to about 75-percent metal content in an air elutriation system. An 8-inch-diameter water elutriation column with a feed capacity of 2.7 tons per hour was constructed and operated. The results obtained were compared with those produced by sink-float methods. Tests made on duplicate samples of an intermediate-grade metal product were successful in upgrading the metal con-tent from 75 percent to 98.7 and 99.1 percent with respective recoveries of 95.5 and 98.9 percent for the water classification and sink-float procedures. Tentative flowsheets for treating junk auto shredder rejects are outlined.

Jan 1, 1972

By Oliver Bowles

The wire saw, introduced by the Bureau of Mines about two years ago, has revolutionized slate quarrying in Pennsylvania. The success of the saw since its early accomplishments has become greater and greater as the equipment has been perfected and skill acquired .in its use. In the first test made, a cutting rate of 9.7 square feet per hour was attained; in the next four cuts, made early in 1927, the average rate of cutting was increased to 12.8 square feet per hour; in 1928 a maximum of 34 square feet per hour had been attained, with a general average of about 20 to 25 square feet, The wire saw is now regarded as essential equipment in practically all of the quarries in the Bangor, Pen Argyl, and Windgap districts. The wire saw consists of a three-strand steel cable of 3/16 or 1/4 inch diameter running as an endless belt. The driving pulley is a 40-inch double-groove cast-iron sheave. A tension pulley supported by a frame mounted on wheels may travel back and forth on a short track. A weight of 800 to 2,000 pounds gives the desired tension on the wire. The driving units consist of electric motors with direct-drive compactly enclosed gear reduction, or double-belt speed-reduction units; the former is preferred. Silent chain and. pinion gear reductions are used to a limited extent. The travelling speed of the wire is about 15 feet per second. The driving and tension equipment are shown in Figure 1, A.

Jan 1, 1929

By Charles W. Huggins

Knoop hardness indentations were studied and measured with the electron microscope on TiB2, HfC, and A1B12 crystals. A detailed description of replicating the indentations using collodion and Faxfilm is made. A John Hopkins grating having 28,800 lines per inch was used to accurately determine the magnification used on the electron microscope. The primary objectives were to prepare carbon replicas of hardness indentations, to measure the indenations accurately, and to compare the results with those obtained with the light microscope. The resulting data showed excellent agreement between the measurements made on the replicas with the electron microscope and those made with the optical microscope. The replicas made from collodion showed slightly better agreement with the light optical values than did the replicas made from Faxfilm.

Jan 1, 1963

By John P. Savage

This paper is one of a series being prepared by the United States Bureau of Mines on tunneling methods. The tunneling methods described are those used at the Ojuela unit of the Compania Minera de Penoles, S. A., the Mexican subsidiary of the American Metal Co., Ltd., of New York. The Ojuela unit is situated some 4 miles southeast of Mapimi, Durango. Mexico, the latter place being connected by a 15-mile narrow-gage railway with the standard gage railroad at Bermejillo, some 40 miles to the north of Torreon, the location of one of the company's smelters.

Jan 1, 1931

By Oliver Bowles

Wire saws have been used for many years in European travertine, marble, and slate quarries. This method of sawing found very limited use in America until 1927 when it was accepted as standard equipment in elate quarries in Pennsylvania where it has been remarkably successful. Details of its operation in slate have been published in a recent bureau report.3 The very limited extent to which the wire saw has been employed in limestone and marble quarries in the United States and the seeming lack of interest even in experimental work to determine its advantages are difficult to explain in vied of its wide use in cutting similar rocks in Europe and its unquestionable advantages in sewing slate in America. In order to encourage improvement in quarry practice the United States Bureau of Mines has endeavored to obtain information as to the extent to which wire saws are used in Europe together with data on the rate and cost of sawing. The information at hand is by no means complete either in territory covered or in details of operation; it nevertheless brings out certain significant features that may be of interest and advantage to quarrymen in the United States.

Jan 1, 1931

By Sam S. Taylor

In most oil fields, natural gas is the major source of energy causing flow of oil to the well. The amount of gas produced with the oil generally exceeds actual energy requirements, so that in time the gas reserve of the field becomes seriously depleted and the oil production must be stimulated by some auxiliary means. One of these is to repressure the oil formation with natural gas; or, where a as supply is not available, often air is used. Although air is a cheap and convenient repressuring medium, its use sometimes is attended with several disadvantages. First, the return air-gas mixture decreases rapidly in fuel value, often until it can be used no longer as a source of power. At the same time, explosive mixtures may result if recycling is used, causing hazards to life and equipment. Second, sortie fields experience considerable trouble with the formation of emulsions which become increasingly difficult to treat. Although there is no definite proof that air repressuring always causes these emulsions, many operators are convinced that this is the case. The Petroleum Experiment Station of the United States Bureau of Mines at Bartlesville, Okla., has been interested in problems connected with air-repressuring for a number of years. Some time was spent in studying the so-called "bad gas"--return mixture of low fuel value. However, it appeared impossible to attack the problem successfully from this angle, and an approach was made through a laboratory-scale study of direct oxidation of crude oil.

Jan 1, 1934

By Wilder D. Foster

In the method used in the Health Branch of the Bureau of Mines for petro-graphic identification of the minerals in a rock, the sample is crushed, ground to a fine powder in a mortar, the powder is put on a slide, a drop of index oil and a cover slip are added, and the slide is ready for examination. The rock should be ground fine enough so that most of the particles consist of only one mineral, otherwise identification is difficult. Finally, the amounts of the minerals present in the sample are estimated to the nearest 5 or 10 percent. When quartz grains are mixed with some claylike minerals) of which by far the most common example is quartz and kaolinite in a shale, grinding in a mortar does not always separate the quartz from the kaolinite; instead, the quartz grains become coated with the kaolinite and are not visible, even after careful search. Talc acts Similarly, but muscovite and pyrophyllite do not. In evaluating the possible silicosis hazard of breathing dust from a shale, it is essential to be able to see and identify all of the quartz grains, as the other minerals present are relatively innocuous.

Jan 1, 1949

By W. D. Mcmillan

The Dempsey tract in Washington County, Mo., had a small production of lead-zinc ore from shallow workings. Old dumps from early-day lead mining contain about 25,000 tons of ore averaging about 3 percent combined zinc and lead. Because of the urgent war requirements for lead and zinc, the Dempsey property was examined by Otto Ruhl, formerly an engineer of the Bureau of Mines in August 1942 and selected for further investigation by churn drilling twenty holes totaling 1,309 feet were bored in the fall of 1943. The results of the work are presented in this paper.

Jan 1, 1948

By J. E. Chilton

The Bureau of Mines has developed a portable flammable gas detecting system for estimating the flammable gas concentrations in a mine containing one or more combustible gases at concentrations up to 100 vol pct. With this portable detecting system, mine rescue or recovery personnel can quickly determine if they are working in a potentially explosive gas atmosphere and either leave the area or make appropriate changes in the fresh air ventilation of the mine to render the area safe. The detecting system uses a commercial, intrinsically safe, flammable gas detector with a range from 0 to 5 vol pct methane (CH4). The flammable gas detector has a catalytic heat-of-combustion sensor that can detect all flammable gases that would be encountered in a mine including methane (CH4), ethane (C2H6), carbon monoxide (CO), and hydrogen (H2). To determine the mine gas concentration, the rescue worker dilutes a sample with fresh air carried within the detecting system. The concentration of the diluted sample is then measured with the permissable flammable gas detector. The actual mine gas concentration is calculated from the product of the indicated diluted gas concentration and the system dilution ratio using a pocket calculator or the nomograph on the side of the unit.

Jan 1, 1987

A spectrochemical procedure applicable to the determination of iron, manganese, and magnesium in titanium metal and to the determination of alloying constituents in three types of titanium alloys is presented. Acid solutions of samples and standards are excited with a spark-type discharge and porous-cup electrode arrangement. The method is particularly applicable for analyzing samples for which a self-electrode method cannot be used. Calibrations are accomplished with synthetic standard solutions, resulting in a primary method that makes calibrations based upon results of other analytical methods unnecessary. Replicate determinations are reproduced to within 5 percent, and the average percentage deviations from reliable chemical values are less than 6 percent. The method can be extended readily to determine additional elements that are similarly soluble and have similar spectral sensitivities. It also can be used as a starting point to establish standards for a direct sparking procedure for analyzing titanium alloys. In view of the absence of established reliable analytical methods in the titanium industry, the spectrochemical method described here should prove to be a timely contribution.

Jan 1, 1956

By James E. Bell, Clyde B. White

"INTRODUCTION The Friedensville district was one of the most important zinc-producing areas in the United States from 1859 to 1893. The ore minerals near the surface were principally calamine and smithsonite, but with depth sphalerite was found in increasing proportions. The ore bodies of the district are reported to have been in chimneys, occurring in folded and faulted beds of Beekmantown limestone of Ordovician age.The Correll was one of five mines near Friedensyille that were exten¬sively exploited. The high-grade ore shoots were mined to a depth of several hundred feet, but it is believed that inability to compete with lower-cost production elsewhere, rather than exhaustion of the ore bodies, compelled the mines to close.There is no record to indicate that any attempt was made during the period of operation to explore for additional ore in the limestone beds down the dip below the mine workings. The possibility that exploration might reveal additional ore in the limestone beds below the known ore shoots led the Bureau of Mines to diamond-drill the Correll property between September 1943 and January 1944."

Jan 1, 1948

By Jeffrey P. Schubert

The study site in northeastern Illinois underwent surface mining for coal in 1943 and was reclaimed by the state of Illinois in 1972-1973. Additional soil amendments and seed were applied to the spoil surface in 1975-1980. Previous studies in 1975-1978 had shown that the surface spoil materials and five final-cut lakes at the site were quite acidic and the lakes contained high concentrations of sulfate and dissolved metals. Surface runoff water from monitoring plots in 1976 were only moderately acidic and the mean concentrations of most dissolved metals and sulfate in the runoff waters were less than 25% of the concentrations found in Lake B. By 1980, vegetation had become well established over most of the mined area. However, the five final-cut lakes (Lakes A-E) remained acidic. The purpose of the study reported here was to determine the physical and geochemical subsurface conditions of the spoil materials, the hydrologic flow system within the spoils, and the magnitude of acidic spoil leachate migration into the lakes and into the wetland prairie north of the mine site. Lakes A, B, C, and E were still very acidic in 1980-1981 (pH range: 2.9-3.4; aridity range: 110-860 mg/L as CaCO3). Lake B had the worst water quality, with mean concentrations of dissolved aluminum, iron, manganese, and sulfate of 75, 25, 37, and 3340 mg/L, respectively. Shallow groundwaters in spoil materials around Lake B had a lower pH and about two to four times greater concentrations of aridity, aluminum, manganese, zinc, and other metals and nearly 20 times greater dissolved iron than the water in Lake B. The shallow groundwaters in undisturbed soils and bedrock 10-30 m north of the mine site spoils generally were alkaline, but did contain occasional moderately high sulfate and metal concentrations. Pumping tests and recovery tests conducted in piezometers showed hydraulic conductivities of spoil materials ranging from less than 10- to 10-5 m/s; hydraulic conductivities of natural soils and bedrock were measured between 10-10 to 10-7 m/s. Water levels in spoil materials increased rapidly in response to rainstorm events and the recession curves were relatively quick to decline, lasting only two or three days. Quick infiltration of rainfall into the spoil surface and percolation down to the water table caused a rise in groundwater levels and movement of spoil groundwater into the lakes. This groundwater component in the lake water budgets could account for most of the water quality problems occurring in the acid lakes.

Jan 1, 1984

By Douglas C. Corner

This is the first of a series of papers dealing with modern tunnel-driving methods, compiled in accordance with an outline prepared by engineers of the United States Bureau of Mines and to be published in a series of information circulars by the bureau. This series will supplement a similar and earlier series of papers dealing with mining methods and costs. ACKNOWLEDGMENTS The author desires to express hiss appreciation, of the assistance of A. C. Dennis, manager for the West Construction Co. Contractors, and Franc: E. Winsor, chief engineer for the Boston Metropolitan District mater Supply Commission who furnished much of the data and detailed description of operation appearing in the following pages. C. F, Jackson, mining engineer, United States Bureau of Mines, collaborated in the preparation and arrangement of the text.

Jan 1, 1931

By R. L. Crosby

The Bureau of Mines investigated alloys of copper with 2, 3, and 4 vol pct alumina and with 2 vol pct yttria. Alloys were prepared by a coprecipitation process and were fabricated by pressing and sintering of powders, extrusion, and swaging. Tensile properties at room and elevated temperatures, stress-rupture strength, electrical conductivity, and density were measured. The superiority in elevated temperature strength of dispersion-strengthened copper to OFHC copper was confirmed. Increasing the oxide content from 2 to 4 vol pct produced only a small improvement in strength properties and decreased the electrical conductivity. The 3 vol pet alumina alloy had the best overall combination of properties.

Jan 1, 1969

By J. R. Thoenen

During the past 6 years the Mining Division of the U.S. Bureau of Mines has prepared many information circulars containing valuable technical data covering the operating details of mining and ore-dressing plants throughout the United States, Canada, Mexico, and other countries. These papers, written for the most part by operating officials in the field, have been designed to comprise a reference library for the operating engineer. In order to make the information contained in these publications more readily available to the busy engineer the enclosed series of reference tables has been compiled. The tabular arrangement is by subject rather than alphabetical order, thus avoiding the bulk of an alphabetical index.

Jan 1, 1935

By B. K. Shibler

A highly flexible laboratory-scale fluidized-bed reactor was designed, constructed, and successfully operated continuously at temperatures up to 1,300° C during an investigation of thermal methods for decomposing gypsum. This report discusses briefly the many problems encountered in developing the 10-inch-diameter reactor and describes its design and construction in sufficient detail to enable other research organizations to build a comparable unit. The reactor consists of a 10-inch-inside-diameter vertical tube which can be varied from 6 to 10 feet high; it is formed from 2-and 3-foot sections of silicon carbide pipe. The tube is surrounded by a 3-inch heating space formed by an outer 4.5-inch-thick circular wall of insulating firebrick. A cone-shaped fluidizing chamber is bolted to the bottom of the reactor. Fluidizing gas enters through the bottom of the cone, and ore is introduced by means of a screw feeder connected to an inlet located just above the gas port. A silicon carbide overflow tube of 1.25-inch inside diameter extends upward into the reactor. The depth of the bed is controlled by substituting different lengths of overflow tube. Twin dust-recovery systems, each composed of a cyclone and Fiberglas filter, are attached to two gas outlets at the top of the reactor tube. The reactor is designed for research on both exothermic and highly endothermic reactions. It can be fired externally by means of four natural gas burners that jet tangentially into the annular space at the base of the reactor. Alternatively, it can be fired internally, using a mixture of air or oxygen and natural gas as the fluidizing medium. A separate instrument panel contains flowmeters, manometers, an automatic program controller, and a multiple-point recorder for printing a record of the temperatures measured by thermocouples located at critical points in the reactor.

Jan 1, 1963