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By C. C. Shale

Electrical resistivities for various coal ashes in air and in a nitrogen atmosphere are given over the range 100° to 1,500° F. Resistivity of low-carbon ash in air is very high at low temperature, rises to a maximum at about 250° F, decreases very rapidly with increasing temperature to about 800° F, then decreases gradually to approach an asymptote at 1,500° F. Resistivity of high-carbon ash in air follows this same general trend at values which are much lower and are proportional to the carbon content. After the carbon has been burned off, resistivity of the remaining ash approaches the high values corresponding to low-carbon ash of similar chemistry. Two factorial experiments show the effects of temperature, particle size, chemical content, and compressibility on the resistivities of four fly ashes of widely different chemical composition in the temperature range proposed for coal-fired turbines. Resistivities of all low-carbon ashes tested fall in the range 106 to 107 ohm cm at 1,500° F and should be removable by electrostatic precipitators. Ashes containing carbon in excess of about 8 percent, however, have low resistivity (as determined in nitrogen), especially at high temperatures. Therefore, high-carbon materials may not be collectable in precipitators because the resistivity is below the minimum value necessary for precipitation. Consequently, high carbon residues from partial combustion of coal probably could not be removed effectively at high temperatures.

Jan 1, 1968

By D. L. Boreck

Thick coal seams are common in the Western United States, Many seams are over 50 it thick (some are over 200 ft thick) and are too deep to extract using surface methods. Currently, such deposits are developed using standard "eastern" mining methods which only extract a few feet of total seam thickness, often rendering the remaining coal unminable with current technology. Novel methods that increase thick-seam recovery have been developed and are currently being used in Europe. These methods--high-face single-pass and multislice longwall, longwall caving, and hydraulic mining--have great potential for use in the United States. Successful use of these methods is an objective of the Bureau of Mines. Their use requires, among other things, a full evaluation of geologic features common to thick coals. The objective of this report is to present and summarize those features that will affect the introduction of the methods into thick-seam mines in the Western United States. The geologic elements delineated are three-dimensional configuration of the seam, cleat development, joints and fractures, roof and floor lithology, and faulting.

Jan 1, 1986

By Roy C. Bartholomae

An accurate characterization of the vibration environment and a vibration qualification test derived from it will be a very useful tool for manufacturers of instrumentation for use on underground coal mining equipment. Recognizing this, the Bureau of Mines sponsored a study wherein vibration levels were measured on mining equipment to form a basis for developing the required vibration test. The data base was composed of 160 samples taken at different positions on a variety of underground machinery. The data were analyzed and presented in a format typical of military vibration qualification tests. The form was shown to be virtually identical to the swept sine test envelope specified in MIL-STD-810B for tracked vehicles.

Jan 1, 1982

By Martin H. Stanczyk

Freezing to dewater typical Florida phosphate rock slime as demonstrated in laboratory tests appeared to have potential commercial use because of indicated moderate energy requirements, good compaction of dewatered solids, and effective recovery of usable water. After freezing, thawing, decanting, and filtering, batch freezing of gallon-size 13.7 percent solids slime samples yielded 42 percent solids products. Cationic amine, used as a process additive, yielded 46.8 percent solids product with significant filter area reduction. Semicontinuous 8 stage freezing tests also produced thickened slimes. Cooling and freezing 13.7 percent solids slime from 30° to minus 10° C required removal of 183 Btu per pound of slime; Carnot cycle calculation indicated that the theoretical minimum energy to transfer this heat was 27.8 Btu per pound. To produce 1 ton of 44 percent solids slime from 13.7 percent sol-ids slime, the calculated theoretical energy required for cooling and freezing was 52.3 kilowatt-hours. During the research heat capacity and heat of fusion data were determined for the slime at various percent solids.

Jan 1, 1971

By J. Roger Loebenstein

Small amounts of arsenic trioxide were shipped in 1988 from remaining stocks at ASARCO Incorporated's closed plant at Tacoma, WA. Imports of arsenic trioxide were at about the same level in 1988 as in the previous year. Legislation and Government Programs The Occupational Safety and Health Administration (OSHA) levied a $1.6 million fine against Asarco for exposing its workers at its East Helena lead smelter in Helena, MT, to unacceptably high levels of lead and arsenic. The bulk of the fine was for violations of a respiratory protection program. The same smelter and its environs has been listed as a Superfund toxic-waste site by the Environmental Protection Agency (EPA). Tests had shown high levels of lead, cadmium, and arsenic in the soil near the smelter. EPA planned to extend the cleanup to areas within the town of East Helena because high levels of arsenic had been found in shallow test wells outside the smelter site. Federal and State health officials have warned residents living in the vicinity of East Helena to avoid eating certain home-grown vegetables because of high concentrations of heavy metals.2

Jan 1, 1990

By Scott Turner

The settlers of a new country necessarily suffer at first from the lack of accumulated stocks of metals - in-use that are possessed in older countries . Our American colonists were at first compelled to import their metals in manufactured forms , and it must have proved difficult to produce an exportable surplus of commodities with which to pay for them . These circumstances stimulated a search for domestic ore deposits . Various discoveries resulted , so that as early as 1628 , we find the colonists importing two craftsmen from England to establish iron -works in Massachusetts to beneficiate local ores . In 1648 , an iron -works at Lynn was producing metal at an annual rate of 400 tons . Later on , the colonial iron industries became of importance , some metal being actually exported to England . The people of this country thus early became convinced of the necessity for domestic mineral production . It is now little realized how persistent were their efforts to - make mineral discoveries , before the gold- rush to California ; the extraordinary success of our subsequent mineral explorations has overshadowed the earlier record . Precise and complete accounting of our mineral production , having the character of national bookkeeping , is available only for the series of years beginning with 1880 , when commences the official record that is provided by the Government publication called Mineral Resources of the United States . In the period of 52 years , from 1880 through 1932 , the value of mineral production of the United States amounted to more than 122 billion dollars . Only 12 billions of this total were produced in the 21 years , 1880-1900 , while nearly 110 billions were produced in the first 31 years of the present century . Of this 110 billions , over 53 billions were produced in the most recent decade , 1921- 1930 , the production of the previous decade , 1911-1920 , having been only 37 billions , though it included the war period ; that of the decade 1901-1910 was 16 billions . In 1931 , the total value of mineral products of the United States was $ 3,180,000,000 , compared with an average annual value of $ 5,556,000,000 during the previous five - year period , 1926-1930 . The decline in 1931 from that average was therefore 43 per cent . As to the three great groups of mineral commodities , metals fared worst , with a decline of 55 per cent in the value of their production , while the value of fuels declined 39 per cent , as did that of the nonmetals group .

Jan 1, 1933

By M. H. Stanczyk

Bench-scale laboratory tests were made by the Bureau of Mines of a segregation-flotation concentrate, assaying 20.43 percent copper, to investigate the influence of various ratios and concentrations of ammonia and carbon dioxide on copper extraction. Leaching the concentrate with a solution containing 900 pounds of ammonia and 360 pounds of carbon dioxide per ton of feed, followed by washing the leach residue with 1.75 tons of a 10-percent solution of ammonium carbonate and about 1 ton of water (as steam) per ton of solids, resulted in a copper recovery of 96.3 percent. Resegregation and flotation tests of the washed residues revealed that 85 percent of the copper in the residue could be recovered. Steam distillation tests of a typical ammoniacal leach liquor, assaying 39 grams copper, 105 grams ammonia, and 77 grams carbon dioxide per liter, recovered over 99 percent of the copper as a mixed oxide-carbonate precipitate. The ammonia losses in leaching, filtering, washing, and distillation were 0.12 pound per pound of copper recovered in the precipitate. Calcination and subsequent hydrogen reduction of the precipitate yielded a metallic copper powder assaying 98 percent Cu, 0.87 percent Si02, 0.10 percent MgO, 0.54 percent CaO, and 0.41 percent R203.

Jan 1, 1961

By L. A. Neumeier

The Bureau of Mines evaluated creep and other properties of extruded Zn-30 pct-AI alloys containing 0 to 0.7 pct Mg. The alloys were extruded both above and below the Zn-Al eutectoid temperature of 275° C. Creep behavior is defined for the alloys as extruded and after various heat treatments. Tensile properties, hardness, thermal expansivity, impact resistance, and microstructures are given. The alloys, either with or without magnesium, required substantially less pressure for extrusion near 275° C than at higher or lower temperatures. The alloys containing magnesium exhibited significantly greater hardness, tensile strength, and creep resistance, but much lower ductility than the 2n-30 pct Al alloy. The properties were very sensitive to the processing conditions.

Jan 1, 1971

By L. J. Froisland

The Bureau of Mines conducted a 4-year research program at Uravan, Colo., on a 2-1/2-acre reclamation plot on the slope of a uranium tailings pile that had been covered with mine waste rock. The purpose of this study was to determine the effects of plant species, type of irrigation, type of fertilizers, and use of dust control chemicals on plant growth and surface coverage. Best grass coverage, nearly 100 percent with 240 plants per square foot, was developed in a section that was seeded with crested wheatgrass, fertilized with sewage sludge, and sprinkler irrigated. For comparison, a section that had been treated with commercial fertilizers developed 3.1 crested wheatgrass plants per square foot and 24 percent coverage without irrigation, and 8 plants per square foot and 75 percent coverage with irrigation. Results of spraying a dust control chemical were inconclusive. Russian-thistle invaded all test sections and ranged in density from 0.6 to 7.3 plants per square foot.

Jan 1, 1982

By L. W. Higley

Procedures were developed for reclaiming high-temperature alloy scrap in the form of standard cobalt-base alloy. A cobalt-base, multicomponent, high- temperature alloy, such as S-816, can be successfully melted from scrap, and its specified chemical composition can be retained. Induction furnace melting in a controlled atmosphere was used to obtain ingots that were subsequently fabricated by impact forging to provide specimens for heat treatment and testing. Of the numerous metal elements in S-816 alloy, only small quantities of molybdenum were lost in the melting operation as finally developed. Test results indicated that the scrap material, after melting, forging, and heat treatment, was equivalent in room-temperature tensile strength, in high-temperature creep and stress-rupture properties, and in chemical composition to commercially produced S-816 alloy made from virgin material.

Jan 1, 1963

By David C. McHuron

The U. S. Bureau of Mines in their continuing research into sealants, selected MBAssociates to design, build, and test equipment and evaluate sealant as to its effectiveness is shale degradation. There were 20,050 sq.ft. of coal mine roof sprayed with a mine sealant and as a result, it has been estimated that the sealant coated roof has from 50% to 95% less roof falls than that roof which was not coated with sealant.

Jan 1, 1980

By J. Burlin Johnson

In small-scale blasting experiments conducted in the Bureau of Mines laboratory, small charges were used to produce craters in blocks of concrete mortar. The results are compared with larger scale experiments of other research workers, and the comparison demonstrates the similarity of the results obtained and indicates that small-scale blasting should be a useful tool for predicting large-scale blasting effects. INTRODUCTION The purpose at this investigation was to conduct blasting experiments in mortar in the laboratory and then, by comparing the results with those from larger scale field blasts in rock to determine to what extent, if any, the laboratory results resemble those in the field. The work described herein was the initial phase of a project aimed at evaluating small-scale blasting as a tool for use in improving blasting techniques. It is evident from the stand-point of control and cost that small-scale blasting would be valuable in the study of rock fragmentation by blasting in mines and quarries, if the extrapolation is valid.

Jan 1, 1962

Provide the U.S. mining industry with a user friendly computer program to calculate stresses in underground coal mines in order to improve safety conditions for mine workers. Capabilities of MULSIM/NL MULSIM/NL (multiple seams, nonlinear) is a three-dimensional boundary-element method (BEM) program developed at the U.S. Bureau of Mines for stress and displacement analysis of coal mines. It can analyze one or two parallel seams that can have any orientation with respect to the Earth's surface. Three main new features distinguish MULSIM/NL from its predecessors: (1) non¬linear material models, (2) multiple mining steps, and (3) energy release and strain energy computations. MULSIM/NL has six material models for the in-seam material: (1) linear elastic for coal, (2) strain softening, (3) elastic plastic, (4) bilinear hardening, (5) strain hardening, and (6) linear elastic for gob. The multiple mining step capability enables the user to efficiently simulate a changing mine geometry. Finally, MULSIM/ NL computes energy release rate due to mining using the most recent concepts advanced by Salamon.

Jan 1, 1993

By Elaine T. Cullen

Safety training materials appropriate for specific underground noncoal operations in the United States are often outdated or nonexistent. The Spokane Research Laboratory (SRL) of the National Institute for Occupational Safety and H ealth has developed several new training tools, including three videos on common underground activities, software that will allow trainers to create a virtual training mine using their own mine map, and toolbox training materials. SRL is working closely with industry in the development of these tools. Teams of safety professionals are involved in the early stages, and actual mines and miners are involved throughout the production phase. This presentation describes the development process and results of SRL’s safety training projects.

By Robert L. Chufo

The U.S. Department of Energy Pittsburgh Research Center,1 has developed and field tested a spatial, spectral sensor for measuring the thickness of mineral deposits. Knowledge of the dielectric constant of the material is not necessary because the electrical properties of the media are determined automatically along with the thickness or distance measurement. The technology was developed to measure the thickness of coal remaining in the roof and floor of a mine or the thickness of a coal pillar remaining between two mining entries for the purpose of guiding a mining machine. However, field tests have shown the new technique is equally valuable for measuring the thickness of each layer in a multilayer manmade structure such as highway paving or building foundations and the thickness of geological deposits other than coal, such as, salt, granite and sandstone. The noncontacting electromagnetic technique uses spatial modulation created by moving a simple dipole sensor antenna in a direction along each axes to be measured while the complex reflection coefficient is measured at multiple frequencies over a two-to-one bandwidth. The antenna motion imparts spatial modulation to the data and enables frequency domain signal processing to solve the problem of media, target and antenna dispersion. The technique overcomes the problem of multipath reflections from nearby metal structures and avoids the use of radio frequency absorbing material. In its present form the system measures material thickness of zero to over 3 m to within ±2.5 cm accuracy. The system parameters are variable to suit the application but for most applications default values of 40 cm antenna motion with measurements made at 401 frequencies from 0.6 to 1.4 GHz at each of 32 antenna positions with a power level of 0 dBm or less are more than adequate to provide a satisfactory signal-to noise ratio. In the range of 0 to 10 m the system operates in the continuous wave mode and by simply turning off the transmitter for ranges beyond 10 m the problems of time domain processing are entirely avoided. The technique can be implemented with a vector network analyzer, a servo controlled L-band antenna positioner, an IEEE488 bus controller and a process computer. An electronics package designed and constructed to operate in the harsh mining environment and providing 1, 2 or 3 dimensional image presentation is being evaluated as a replacement for the network analyzer. Key words: Ground penetration radar, Spatial, Spectral

By H. Schultz

Urban refuse that was mechanically separated at the U S Bureau of Mines pilot plant in College Park, Md., was successfully evaluated for its fuel values using standard coal analysis methods. Analyses performed on refuse samples taken from five sample points included moisture, ash, sulfur, chlorine, and heating value. It was recommended that characterization of the combustible portion of urban refuse by standard coal analysis procedures should be widely adopted.

Jan 1, 1975

By Philip W. Holland

The U.S. Bureau of Mines has designed and built an inexpensive, weatherproof, temperature-controlled cabinet to provide temporary housing for analytical instrumentation. The cabinet consists of an inverted Styrofoam ice chest, an electric fan for air circulation, and a proportional temperature controller equipped with a thermistor sensor and a light bulb as the heater. The cabinet provides a constant-temperature environment for a moisture analyzer and a strip chart recorder when outside temperatures range from -SO to 21° c.

Jan 1, 1993

By W. C. Phalen

"The Phosphate Rock Market:Indications, in the fertilizer market, point to a prosperous condition, caused chiefly by the growing demand for all classes of fertilizer material in spite of a shortage of supplies. Both of these conditions have been caused by the war. The shortage in phosphate rock is being relieved as production increases, but the supply has not caught up with the demand for this spring's trade, at least. Reports from Florida are to the effect that more than half the necessary quota of laborers are at work. This may not appear to be a very good showing, but even this situation is en¬couraging because there is a larger force now at work than has been the case for some time, and it is steadily, though slowly, increasing. Some of the producing companies are conducting advertising campaigns to get laborers back to the phosphate fields and attractions in the way of better housing and living conditions are being offered.Producers are far more confident about the situation than they were two months ago, and though the shortage will not be met before the end of 1920, theme is a surplus accumulating over what is going out on existing contracts.Quotations are now being offered on all Florida rock excepting land pebble and this, it is expected, will be soon quoted.Quotations on Florida rock per ton are as follows:"

Jan 1, 1920

By Michael S. Miller

The U.S. Bureau of Mines (USBM) conducted mineral investigations in the 1,227,000-acre Emigrant Trail study area of Nevada during 1992. During the USBM investigation of 25 areas of development interest, 190 mineral localities were identified and 260 rock and 50 alluvial samples were taken. At least 0.5 million troy ounces of gold, 2.3 million troy ounces of silver, 3.3 million pounds of copper, 10.9 million pounds of lead, 2.4 million pounds of zinc, 500 tons of alunite, 40,000 tons of sulfur, 9,000 pounds of mercury, and 21,000 pounds of tin have been mined from the area and vicinity. Adjacent to the study area, gold is being mined at large, open-pit gold mines, the Hog Ranch and Hycroft Resources, Inc., Sulphur mines, and new production is planned at the Rosebud LAC/Equinox. Hog Ranch mine is nearing depletion, but resources of more than 0.5 million troy ounces of gold and about 5 million ounces of silver are estimated for the Rosebud LAC/Equinox project and more than 0.4 million ounces of gold for the Hycroft Resources, Inc., Sulphur mine. Significant investigations are occurring at SP Ridge and other sites near Scossa and at the Dan claims in the Southern Calico Mountains. Precious opal, placer gold, and geothermal energy resources occur in the study area and vicinity.

Jan 1, 1993

By Jacob N. Frank

A factorially designed, hydraulic fragmentation experiment using a high-pressure water jet was conducted on concrete blocks. Three levels of pressure, standoff distance, and impact angle and two levels of traverse time and surface condition were used. Three variables were measured: depth of penetration, volume of material removed, and width of slot. Three stepwise linear regression equations were developed from the jet parameters and the physical properties of the concrete. The three basic equations, describing the significant jet parameters and physical properties, were developed into 15 predictor equations, five for each variable investigated. Direct regression equations were also developed for each variable investigated to show the result of increasing or decreasing each significant variable. Energy efficiencies were developed for the experiment and for each significant factorial variable.

Jan 1, 1971