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By John E. Shelton

Flotation tests were conducted on two samples of copper-nickel-bearing ore from the Harriman area near Rockport, Maine. The samples were taken by Roland F. Beers, Inc., for tests in cooperation with the Federal Bureau of Mines. One sample, analyzing 0.38 percent copper and 0.71 percent nickel, was essentially a disseminated pyrrhotite in hypersthene. Pentlandite, chalcopyrite, pyrite, and millerite were intimately associated with the pyrrhotite. Locked series flotation tests on this sample showed that 87.4 and 73.4 percent of the copper and nickel, respectively, could be recovered in a bulk concentrate that analyzed 3.47 percent copper and 5.34 percent nickel. The copper-and nickel-bearing minerals were collected with sulfhydric collectors in an alkaline circuit. Cleaning the concentrate three times with the addition of pH regulators was sufficient to attain the previously stated grades. The second sample had analyses of 0.31 percent copper and 0.85 percent nickel; talc and hypersthene were the main gangue minerals. Bulk sulfide flotation, made while depressing the talc, resulted in a concentrate that analyzed 2.33 percent copper and 4.70 percent nickel at recoveries of 70.0 and 54.4 percent, respectively. Flotation of the talc followed by bulk sulfide flotation resulted in a nickel content greater than 5 percent. A locked-series test showed that 60.7 percent of the copper and 73.7 percent of the nickel could be recovered at grades of 1.29 and 4.85 percent, respectively.

Jan 1, 1961

By Phillip N. Yasnowsky

This Bureau of Mines report examines the percentage depletion allowance rate structure in relation to several criteria that are indicative of U.S. mineral import dependence. These criteria are the minerals considered as strategic and critical for stockpiling purposes, the ratio of reserves to forecast cumulative demand (1976-2000) for selected minerals, and the U.S. net import reliance as a percentage of apparent consumption (1978), also for selected minerals in general, it was Found that there does exist a direct, although not perfect, relationship between the percentage depletion allowance rates and the degree of import dependence as indicated by these three criteria. The higher percentage rates tend to he associated with those minerals for which the United States is, or will likely he, heavily dependent on foreign sources. In addition, a basic discussion of the mineral depletion allowance is provided, including numerical examples illustrating the computation of the allowance under several assumptions. Also, the percentage depletion allowance rates for individual minerals are tabulated.

Jan 1, 1980

By J. J. Drost

The feasibility of basic oxygen furnace (BOF) offgas heat recuperation by preheating scrap was investigated on a pilot plant scale by the Bureau of Mines. In this study, offgases generated during the oxygen blowing of a molten pig iron and scrap charge were passed through a static bed of shredded auto scrap. Scrap quantities varying from 100 to 180 pounds and representing from 22 to 40 percent of the 450-pound BOF metallic charge were preheated in this manner. Average scrap bed temperatures of 1,650° F for 100 pounds of scrap and 1,150° F for 180 pounds of scrap have been achieved during the blows. As compared to cold scrap used in the normal BOF practice, it was found that by preheating scrap, usage could be increased by 43 percent. The thermal energy recovered by this preheating method can account for up to 44 percent of the energy necessary to melt the scrap.

Jan 1, 1974

By W. A. Cole

As the mines get older and the active workings get Farther and farther away from the original mine openings, it becomes increasingly difficult and expensive to ventilate most coal-mines properly. At the same time, the avenues of escape for those employed underground have become so extended' as often to make it impossible for them to make their way out of the mine in the event of a fire, mine explosion, or other emergency. Where such Conditions exist, the only satisfactory solution is to make new ventilation and emergency-escape openings near the active mine workings. At most mines this would necessitate sinking shafts, which is often slow and expensive.

Jan 1, 1945

By Christopher D. Risbrudt

In this comprehensive study of the use of wood products in coal mining, a sample of over 220 mines provided data by questionnaire. Wood use per ton of underground coal was found to vary substantially by mining process and region. In the Eastern Coal region, 1.6 board feet of wood was used per ton of coal, wel above the 0.6 board feet usage per ton in the West. The kind of timber used varied also by Region. Hardwood use is about 40 times greater than softwood in the Eastern Region. There, hardwoods are plentiful, relatively cheap and strong. In the West where softwood forests predominate, softwoods were 2-1/2 times more common in mine wood use than hardwoods. Nearly 80 percent of the wood used in underground coal mines is used in cross bars and props. Nearly 54 million cubic feet of wood products were used in coal mining in the sample year 1979; about twice as much going to underground mines as surface mines. Wood requirements for mining were projected to 2030 for a range of three oil price scenarios. Much greater wood use will be required for greater coal output.

Jan 1, 1982

By S. A. Matthes

This Bureau of Mines report describes analysis of a copper slag for 13 elements from a single sample solution by flame atomic absorption spectroscopy. Samples are dissolved with 7 ml of an HC1-HF-HN03 (3:1.5:2) mixture in heated plastic pressure vessels. A 1.5-pct boric acid solution is added to dissolve precipitated fluorides and to reduce matrix effects that interfere with atomic absorption analysis. Preparation time is less than 1 hour per batch of 10 samples. Total analysis time is less than 6 person-hours for 130 determinations with an average relative standard deviation of 1.83 pct for the 13 elements. Simple acid standards were used for all determinations. Values obtained by this method are in excellent agreement with values obtained by slower, more costly procedures.

Jan 1, 1980

By C. R. Stephan, N. B. Greninger, S. J. Luzik

The U.S. Bureau of Mines conducted explosion tests on various full-scale cementitious bulkheads used in abandoned mine areas to evaluate the ability of the bulkheads to withstand gas explosion over-pressures of 20 psig. Tests were performed on 120-ft2 solid-concrete-block seals of varying thicknesses and designs. Of the seven solid-concrete-block seals tested, only the standard-type seal, having a 16-in thickness, keyed at the floor and ribs, all joints mortared, wedged at the roof, and a center pilaster, maintained its integrity when subjected to a 20-psig pressure wave. After being subjected to repeated explosions, the standard seal only showed a small hairline crack and had an air leakage of 87 ft3/min at a pressure differential of 1 in H2O. Tests were performed on cementitious foam seals of varying thicknesses and compressive strengths. Explosion tests have shown that 200-psi strength, 4- and 8-ft-thick seals can withstand a 20-psig pressure wave. At a pressure differential of 1 in H20, no air leakage was detected through the 200-psi, 8-ft-thick foam seal.

Jan 1, 1991

By H. E. Powell

A series of alkyl-dithiocarbamic acid amine salts was prepared and tested as collector for slimed lead minerals contained in the waste material from a commercial lead ore concentrator. The reagents, members of a homologous series differing only in the number of alkyl radicals in their structure, were prepared by reacting stoichiometric amounts of primary amines and carbon disulfide in a cold alcohol solution. Subsequent purification was by recrystallization from absolute ethyl alcohol solution. Evaluation was through froth flotation of a mill tailing containing 0.2 percent lead. Results show that maximum recovery (38 percent) was obtained with the reagent containing 8 alkyl radicals, but that maximum rougher concentrate grade (4.8 percent) was obtained with the reagents of intermediate number of radicals.

Jan 1, 1962

By E. H. Denny

"IntroductionOn May 27, 1927, a coal-dust explosion occurred at the Palagua No. 5 mine of the Victor American Fuel Company, Delagua, Colorado, resulting in the loss of even lives and in and in considerable damage to the main slope and to several overcasts the explosion did not extend into the mine working where 125 additional men were employed but escaped uninjured. It is believed that the saving of these 125 men and the evidence of large property loss were due in a large measure to coal-dusting and of other sanity measures taken by the coal company management. A number of features connected with the explosion and mine safety practice seem worth the attention of the mining public and grateful acknowledgment is made to the Victor American Fuel Company for its aid in assembling the data herein contained."

Nov 1, 1927

By M. J. Ferrante

The standard enthalpy of formation, low-temperature heat capacities, and enthalpy increments above 298 K were determined by the Federal Bureau of Mines for synthetic dawsonite [NaA1C03(OH)21. The enthalpy of formation was determined by hydrochloric acid solution calorimetry, with the result ?Hf°298 = -469.4±0.7 kcal/mole. The low-temperature heat capacities were determined from 6 to 307 K by adiabatic calorimetry. Tabulated are low-temperature values of Cp°, S°, and H.-Ho° from 3 to 298 K. The derived entropy at 298 K is S298 = 31.55±0.3 cal/deg mole. Enthalpy increments above 298 K were obtained by copper-block drop calorimetry. Tabular data of Cp°, S°, H°-H°298, -(G°-H°298)/T, ?Hf°, ?Gf°, and log Kf are given from 298 to 477 K. Enthalpies and Gibbs energies of decomposition are also reported.

Jan 1, 1976

By David E. Nicholson

This report investigates the mechanical behavior of fine soils in a lunar environment in engineering gravity-flow bins. The ultrahigh vacuum, absence of moisture, and a lunar gravity one-sixth that of earth gravity represents a unique environment, both advantageous and detrimental to these systems. On earth, moisture and gases contained in powder masses can be responsible for complex descriptions of gravity flow. Their absence appear to simplify the lunar soil behavior. However, simulation of the lunar gravity and vacuum complicates the development of experimental data for designing bins. The properties of a dry soil powder, its behavior under one-dimensional compression, and its torsional and direct shearing strength under earth atmosphere are described in part 1 of this paper. These properties provide the parameters for a finite-element analysis to optimize the design of bins, to be described by Dr. William Pariseau in part 2. Shear tests assess the failure criteria for the material. Compression tests provide modulus and (Ko) stress-ratio values from the loading portion of the compression cycle, duplicating the condition of a bin at rest with the discharge closed. During the unloading portion of the compression cycle (soil overconsolidated), the residual Ko values rise. It is postulated that this phenomenon creates a high-lateral stress in bins when they approach incipient flow. Assessment of the Ko value, overconsolidation ratio, and the void ratio state is proposed as a criterion to determine the flowability of powder.

Jan 1, 1971

Ten years ago we surveyed in "Uspekhi Khimii" the mechanism of the synthesis of hydrocarbons from CO and H2 (1).5 With new data obtained since then, mostly by Soviet researchers, our previous work (2), dealing with new forms and catalysts of the synthesis, is brought up to elate by reviewing research in this field. FORMATION OF CARBIDES The hypothesis that carbides are intermecliates in the synthesis assumes that carbon monoxide reacts with the metals of the eighth group and that this reaction is connected with the reversible reaction 2CO[=]C +CO2 (1) in a certain range of temperatures (3).

Jan 1, 1958

By S. H. Brooks

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

Dec 1, 1923

By A. J. Farstad

The current emphasis on energy needs in the United State sand abroad has placed an increased demand on the coal mining industry. The United States is fortunate to have abundant coal reserves. However, coal mining techniques and technology have not kept pace with the increased demand for coal. Consequently, coal mining in the United States continues to be one of the most hazardous industries. One of the daily hazards faced by coal miners is the sudden and unexpected occurrences of roof falls. The research program described in this final report focuses attention on the problems of unstable roof conditions in coal mines and describes prototype equipment which, with further development, has potential of being able to warn miners of impending roof falls in mines. Westinghouse Electric Corporation, Geophysical Instrumentation Systems Group was awarded a contract to develop and test a microseismic roof fall warning system based on general specifications derived from earlier Bureau of Mines research [1], [2]. During the first year of this two year effort (Contract H0242045) the electronic monitoring systems were de signed and built while the second year of the contract was devoted to equipment field testing in working coal mines.

Jan 1, 1976

By K. O. Bennington

The thermodynamic properties of aegirine, of composition [(Na0.869Fe30+7362 Fe20+16Mn0.03Ca0.1121)(A10.141Sil 9738)(06)], were experimentally determined at the Bureau of Mines as part of its efforts to advance minerals technology. The standard enthalpy of formation determined by hydrofluoric acid solution calorimetry is AHf298 = -641.12±0.73 kcal/mol. The standard enthalpy of formation from the oxides is AH298 = -37.136±0.509 kcal/mol. Low-temperature heat capacities were determined by adiabatic calorimetry from 19.1 to 304.6 K. The derived standard entropy is S298 = 38.03±0.14 cal/mol?K. The heat capacity was measured over the range 348 to 1,198 K by differential scanning calorimetry. These experimentally determined data were combined with data from the litera¬ture to calculate the Gibbs energies of formation and equilibrium constants of form¬ation over the temperature range of the measurements. Standard enthalpies of forma¬tion are given as functions of temperature. The standard Gibbs energy of formation at 298.15 K is AGf298 = -600.36 kcal/mol.

Jan 1, 1984

By N. A. Eilertsen

This report describes field investigations conducted in 1953 of two occurrences of manganese and a separate magnetic anomaly in the Southern manganese district of Aroostook County, vicinity of Houlton, Maine -the Pierce deposits, in Hammond Plantation Township; the Burnham anomaly, also in Hammond Plantation; and the Nickerson-Farm prospect in Hodgdon Township. The manganese occurs in a thinly laminated sedimentary rock containing manganiferous carbonate interlayered with fine-grained metamorphosed sediment, rich in chlorite or hematite. The surrounding rocks are mostly dark gray-green slates. Samples composited for metallurgical testing from the Pierce deposits and the Nickerson-Farm prospect assayed 9.0 to 12.3 percent of manganese. More than 90 percent of the manganese could be extracted with sulfuric acid, but in most instances 30 to 40 percent of the iron was also extracted. Leaching tests indicated that, after being reduced in a hydrogen stmosphere at 600° C., about 85 percent of the manganese could be selectively extracted by a solution of ammonia-ammonium carbonate with iron extraction of only 14 percent.

Jan 1, 1958

By H. G. Iverson

The purpose of this investigation was to beneficiate the Talladega gray iron ores by flotation. A component of the problem was the determination of the degree of beneficiation possible by flotation as well as the relative selectivity of certain reagents in promoting flotation of either the iron minerals or the siliceous gangue minerals. The scope of the present investigation involved only the use of small-scale laboratory equipment. Treatment by roasting and magnetic separation was not included in this study, inasmuch as a similar comprehensive investigation was completed and the results were published by the Bureau of Mines in 1927. The results of the work on Talladega iron ores are briefly summarized in this report. In the search for efficient and economic methods of beneficiating low-grade iron ores, the flotation process is among those that are receiving considerable attention. The Talladega ores are of particular interest for a flotation study, because they contain two iron minerals (magnetite and specular hematite) that are somewhat dissimilar in their flotative response.

Jan 1, 1949

By W. H. Lewis

This Bureau of Mines report and its companion report (Information Circular 9073) have been prepared as a complete reference on underground coal mine lighting. This report discusses system design criteria and procedures, data and specifications to aid in selection of suitable mine lighting hardware, and guidelines for system installation and maintenance. Topics include light measuring techniques and instruments, illumination regulations for underground coal mine environments and equipment, lamps and ballasts, available mine lighting hardware, design and evaluation of coal mine illumination systems, and installation and maintenance of a mine lighting system.

Jan 1, 1986

By F. A. Rutledge

Mercury deposits were discovered in 1941 in the sedimentary rocks of the Cinnabar Crook area, near the head of the Holitna River drainage in southwestern Alaska, by Russell Schaefer and Harvey Wincholl of Sloitmut, Alaska. High-grade float was found in both Canary Gulch and Cinnabar Gulch, and indications of other deposits wore found in Aldor and Broken Shovel Gulches. Schaefer and Winchell's exploration in 1942 and 1943 revealed placer deposits of cinnabar along Canary Gulch. During prospecting on Canary Gulch, 3,600 pounds of ore was recovered from the detrital material on the Lucky Day lode at the head of the gulch. When retorted, this ore was reported by the owners to have produced 26 flacks of quicksilver. During the summer of 1943, Wallace M. Cady and Charles A. Hickcox, of the U. S. Geological Survey, spent 4 weeks mapping and investigating the area. Bruce I. Thomas and Harold C. Pierce, mining engineers of the Bureau of Mines, examined and sampled several deposits in September 1943. Following their preliminary examination, in view of the exceptionally high-grade cinnabar present, additional investigation by the Bureau of Mines was recommended. A program of trenching, test pitting, and sampling to delimit the deposits was completed during the summer of 1947 under the direction of the author.

Jan 1, 1950

By Barry W. Klein

The U.S. economy was considerably stronger in 1976 than in 1974 or 1975. Real gross national product (GNP) rose sharply in the first quarter of 1976 and then increased at a more moderate rate for the remainder of the year. The unemployment rate fell until June and then increased for moat of the remainder of the year, finishing at the same rate as it had started the year. The inflation rate continued to decline in 1976. Reasons for the relatively low rate (compared with those of 1974 and 1975) included small increases in food prices and only moderate increases in energy prices. Total U.S. output measured in terms of GNP increased 11.6% in 1976. Real GNP in 1972 constant dollars rose 6.2%. Inflation as measured by the implicit price deflator increased 5.1%. In real terms, gross private domestic investment for residential structures rose 22.7% in 1976 after declining 14.7%a in 1975; State and local Government expenditures increased 1.4% in 1976; and personal consumption expenditures for services rose 4.5%. The Federal Reserve Board (FRB) index of industrial production increased 10.2%.

Jan 1, 1978