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By D. W. Frommer

Mineral dressing research was conducted by the Federal Bureau of Mines under a cooperative agreement with the St. Joseph Lead Co., on three samples of iron ore from the Pea Ridge deposit in central Missouri. The objective was to provide information on how to upgrade these submarginal ores and produce marketable concentrates. Samples were prepared from drill-hole cores of similar composition and character to produce (1) a medium-grade mixed hematite and magnetite, (2) a high-grade mixed hematite and magnetite, and (3) a high-grade magnetite. In all three ores phosphorus and sulfur constituted objectionable impurities; excessive amounts of silica were also present in the medium-grade ore.

Jan 1, 1960

By Manuel Gomez

Carbon number distributions were obtained for tar acid fractions from five low-temperature tars by low-ionizing voltage mass spectrometry. Quantitative data for phenols representing seven structural compound types were examined by statistical analysis. It was shown that for the phenols discussed, the data could be represented by regression equations expressing phenolic concentration as a function of the reciprocal of the carbon number and the carbon-to-hydrogen ratio of the parent coal. The total concentration of each structural type present was found to depend on the molecular weight and boiling point of the initial member of the group. Carbon distribution data for the tar acid fractions studied support the view that low-temperature tars contain the same chemical compounds but in different proportions.

Jan 1, 1965

By James A. West

THE South Asian countries of India, Ceylon, Pakistan, Afghanistan, Nepal, Bhutan, and Sikkim have a large variety of mineral resources; however, in spite of mineral industry growth during 1964, development of resources remained far short of possible development, and, in terms of value of trade in minerals, the area remained a sizeable net importer. India's mineral industry is by far the most significant; its minerals production in 1964 accounted for more than 90 per cent of the total value of all minerals produced in the area. The total value of all minerals produced in South Asia in 1964 was only about 1 percent of the area's estimated gross national product of $55,125 million. Despite the rather small current contribution of minerals to the economy, development of mineral resources figures prominently in plans for the industrial development of the nations of this area.

Jan 1, 1966

By Joseph Cervik, J. H. Perkins

The Bureau of Mines has conducted desorption work on fine coal particles at near atmospheric pressure. An apparatus has been developed that uses a capacitance manometer to measure desorption of methane from coal particles up to 2 inches in diameter and pressures up to 1,000 psi. This will make it possible to duplicate the desorption process as it occurs in its natural under- ground environment.

Aug 1, 1970

By H. E. Powell

A laboratory mineral-dressing investigation was conducted by the Federal Bureau of Mines on four limonitic and four sideritic iron ores from the North Basin of the east Texas iron-ore district. The samples, composited from drill cores, were considered representative of the iron-ore reserves of the area. The objectives of this research were twofold: (1) To devise a mineral-dressing method whereby the yield from currently mined east Texas iron ores might be increased and the grade improved, and (2) to extend such treatment to include the lower grade ferruginous materials that are not amenable to beneficiation by simple washing and, therefore, are not being exploited. Of the mineral-dressing methods used in this investigation, magnetic separation of roasted are was shown to be the most effective. Results show that, by this method, a laboratory recovery of 82 percent of the iron is attainable at a grade surpassing that obtained by current plant practice and that both limonite and siderite are amenable to concentration by the process. The existence of large deposits of iron are in eastern Texas has been recognized for over 100 years. These ores were first exploited during the Civil War and were mined intermittently until about 1911. From that time until 1944 when the Defense Plant Corporation financed the erection of three blast furnaces to use these east Texas ores, production was almost at a standstill.4/

Jan 1, 1960

By A. F. Colombo

Infrared spectroscopy employing attenuated total reflectance (ATR) techniques on thin films of dried gelatinized starch solution was used during Bureau of Mines research to determine the structural and impurity differences in starch products and to correlate these characteristics with the flotation response of a nonmagnetic taconite. All of the starch products evaluated gave spectrograms which were characteristic of the anhydroglucose monomer and its polymerization product. Distinct infrared absorption peaks caused by the protein molecule were observed and were used to classify the starches. Correlation of laboratory flotation of calcium-activated gangue from a Mesabi Range nonmagnetic taconite and infrared spectra produced from gelatinized starches showed that protein impurities and linear chain structure limited the effectiveness of starches as iron mineral depressants. Starch products having spectrograms similar to pure amylopectin were generally good depressants for iron oxides, were effective at about one-half the addition that was required for starches that gave infrared responses similar to pure amylose, and yielded acceptable iron concentrates containing 61.5 percent iron and 6.5 percent silica.

Jan 1, 1969

By G. R. Hopkins

A fifth successive record in fuel efficiency was established by the petroleum-refining industry in 1937, when the average heat requirement per barrel of crude oil run to stills was 554,000 3. t. u. compared with 597,000 3. t. u. in 1936. These amounts represent roughly the heat ob¬tainable from a tenth of a barrel of fuel oil (see fig. 1). Innumerable factors can influence heat consumption at rep aeries, but only a few are important enough to be subject to statistical measurement. Foremost of these is the ratio of runs to capacity, it being generally recognized that because the fuel demands for other than stills are comparatively inelastic, total heat requirements do not increase in direct proportion to crude runs. Thus, in 1937, crude runs of 1,183,440,000 barrels wore 11 percent higher than in 1930; the average operating ratio was 93 percent compared with 79 percent in 1936; but the total heat requirement increased only 4 percent, or from 639,149 billion 3. t. u. in 1936 to 663,966 billion 3. t. u. in 1937.

Jan 1, 1938

By J. P. Baur

The sensitivity of radiochemical techniques makes possible the study of the initial-stage sulfuric acid leaching kinetics of chalcopyrite and other copper sulfide minerals. This Bureau of Mines study of the initial leaching of chalcopyrite used techniques to evaluate the molecular and electrochemical processes. High-grade Transvaal chalcopyrite was neutron-irradiated in a TRIGA reactor4 to produce radioisotopes copper-64, iron-59, and sulfur-35. Dissolution rates were measured in the time interval zero to 60 minutes, during which time significant anomalies were observed. First was an initial period of rapid dissolution lasting a few minutes; second, an arrest or ?plateau? region usually lasting from 6 to 10 minutes; third, a second period of dissolution of lesser rate than the first. The effects of solution variables such as pH, oxygen partial pressure, and ferric ion concentration at different temperatures were measured.

Jan 1, 1974

By Steven J. Page

The Bureau of Mines used fiber-laden air to test two identical fibrous aerosol monitors (FAM) in order to establish the FAM-optical count correlation. The FAM is a unique instrument developed by GCA Corp. (GCA) to measure real-time fibrous aerosol concentrations. It will also respond to particulates that have sufficient shape irregularities to possess fiber characteristics such as the 3:1 length: diameter (L:D) aspect ratio. Results of the Bureau's laboratory tests showed that the FAM response is linearly correlated to concentration data obtained using the optical membrane filter count technique approved by the National Institute for Occupational Safety and Health (NIOSH), U.S. Department of Health, Education, and Welfare. A plot of the FAM-optical count correlation showed that FAM concentration readings are generally well within ±25 pct of the optical membrane filter count. Initial tests to estimate the best ratio control setting of the FAM for 5-µm fiber-length discrimination were performed using one instrument only (the ratio control setting determines the minimum threshold fiber length that will be detected by the FAM). The estimated setting was then used to correlate both FAM units. The result was a 65 pct difference in correlation between the two units. It appears that the major factor responsible for this difference was the internal adjustment of the photomultiplier detector sensitivity for each of the two FAM units.

Jan 1, 1980

By W. S. Anderson

The use of flexible liners for support of underground openings has been investigated by the Bureau of Mines. This report presents installation procedures and instrumentation results of a full-scale flexible liner field installation in the Burgin mine. The flexible liner is a part of the mine support system and has provided maintenance-free support for 22 months

Jan 1, 1975

By Francis R. Redfern

Newton's method of solving a nonlinear equation is employed to develop a least-squares acoustic emission source location method in which the spatial residuals of the location equations are minimized. These residuals, related to the distances from the least-squares source location perpendicular to the surfaces described by the location equations, permit location error to be estimated to first order along the spatial axes. The solutions obtained by this method are the best spatial solutions to the location equations in the least-squares sense. Also presented is a procedure by which the geometrical control of a transducer array can be evaluated using the rate of change of source location with fractional velocity change.

Jan 1, 1982

By Victor E. Kral

"SUMMARYA preliminary examination of the Buena Vista iron deposit was made in June 1942 by Paul E. Pesonen, mining engineer of the Bureau of Mines. Subsequent examinations were made by D. W. Butner, of the Bureau, in March 1943, and by the author in July 1944, who recommended exploration by diamond drilling, trenching, and sampling. Work on the project was done during the period March 28 to May 26, 1945.Property holdings, comprising 16 claims known as the Buena Vista group, are situated in sec. 4, T. 24 N., R. 34 E., Mount Diablo base and meridian, north Churchill County, about 37 miles east of Lovelock, Nev.Three diamond-drill holes totaling 575 feet were drilled; 45 small pits and ten trenches, totaling 435 linear feet, were excavated, and 84 channel samples totaling 862 feet were obtained under supervision of the Bureau.Purpose of the project was to determine the possible downward extension of the mineralized sections exposed in the outcrops and to determine grade of the ore.Bureau work was confined to one claim only - the Iron Mountain."

Jun 1, 1947

By Robert K. Koch

Laboratory-scale studies on defluorination of natural and synthetic fluorspars by pyrohydrolysis at 1,500° C. were made to determine the feasibility of developing a process for producing hydrogen fluoride from siliceous fluorspars. It was found that the reaction (at 1,500° C.) is not promising for process development, even though a silica-free offgas can be generated. The primary difficulty is the low hydrogen fluoride content of the offgases; an HF content of 6 percent was the best achieved. Previous research by the Bureau of Mines has demonstrated that offgases averaging 27 percent hydrogen fluoride can be produced under carefully controlled conditions at 1,280° C. The lower temperature process is a better method for production of HF. However, charges in which the CaF to Si02 mole ratio varied from 0.4 to 2 could be processed with similar results. Also, combined alumina and ferric oxide contents up to 25 mole-percent did not noticeably alter the rate of defluorination. Therefore, virtually any natural siliceous fluorspar would respond in essentially the same manner when exposed to water vapor at 1,500° C.

Jan 1, 1962

Part Two of this report is based upon six working memoranda prepared during the first half of 1972 at an early stage in our work for the Bureau of Mines. This work presents preliminary performance estimates of baseband voice and narrowband through-the-earth electromagnetic communications systems of principal interest to the Bureau for operational/ emergency mine communications applications. The calculations were prepared to obtain early indications of the feasibility and governing parameters of such communications systems. They are based on limited, but pertinent, coal mine electromagnetic noise data acquired to-date by Bureau of Mines contractors; on theoretical signal-attenuation characteristics for two transmitter antenna types of present interest to the Bureau and on semi-empirical models which describe the intelligibility of voice communications as a function of the frequency variations of the signal-to-noise ratio across the voiceband. This work examines the cases of baseband voice and narrowband communications for uplink and downlink transmissions, for frequencies up to 3kHz. Downlink transmissions are via a horizontal wire antenna, and uplink transmissions via a vertical-axis loop antenna, for typical mine depths of 300, 600, and 1000 feet. Representative coal-mine overburden conductivities of 10-2 mhos/meter (moderate and common) and 10-1 mhos/ meter (high) were used; the former figure for both voice and narrowband calculations and the latter for narrowband calculations only. Examples of high, moderate, and low, surface and subsurface, harmonic and broadband-impulsive noise conditions were taken from NBS and Westinghouse (WGL) mine noise data, together with examples of high- and low-levels of ELF atmospheric noise taken from M.I.T. Lincoln Laboratory data. The effects of simple voice spectrum shaping techniques on the intelligibility of through-the-earth voice communications are examined, and indexes of intelligibility more broadly based than signal-to-noise ratio are discussed. Finally, a means of overcoming the affects of 60 Hz noise and its harmonics which are the largest contributors to typical audio frequency in-mine noise, is suggested. These feasibility calculations are not intended to serve as definitive and complete treatments, but as a starting point: to establish first-order estimates of the magnitude and variability of transmitter power requirements under different noise, overburden conductivity, and mine depth conditions; to identify relationships, conditions, or frequencies that are likely to limit or enhance system performance; to reveal items requiring further investigation and data still required; and to suggest practical methods for optimizing system performance. These objectives were met by the calculations. Simple experiments to support these calculations can and should be carried out; together with more detailed investigations of specific modulation, coding, noise-suppression, voice-compression and signal-conditioning techniques, aimed at producing through-the-earth operational/emergency mine-communication systems that are not only effective, but practical and economically sound.

Jan 1, 1974

By J. M. Kuchta

The chemical and thermal criteria used for predicting the spontaneous combustion hazard are briefly reviewed and data are presented to characterize the gas desorptions and self-heating tendencies of 29 U.S. coals. Closed vessel desorption experiments showed that CO, CO2, and CH4 are the main gases evolved and that the CO, CO/?O2 index, and 02 absorption rate increase with decreasing rank and increasing oxygen content of the coal. In this Bureau of Mines report, the effects of temperature, moisture, and other variables are discussed together with the application of the data to the complex conditions encountered in a mining environment. An important finding is that the presence of CO alone in a mine is not necessarily an indication of a self-heating reaction of the coal. Based upon experiments conducted in an adiabatic-type calorimeter, the self-heating temperatures of lignite and subbituminous coals can be as low as 30° C, whereas the bituminous coals require a temperature of about 60° C or more. The self-heating hazard is greatest when the coals are dried and exposed to a high humidity condition, apparently as a result of the "heat-of-wetting." Generally, the hazard is greatest with the western coals of the United States.

Jan 1, 1980

By W. H. Coghill, B. W. Gandrud, F. D. DeVaney

"The self-fluxing iron ores of Alabama are the foundation of the thriving iron and steel industry of that State. In addition to these deposits of self fluxing ores there are seams containing practically the same percentages of iron but too much silica. These ores at present are valueless, but if they could be concentrated by reducing the silica content, the ore reserves of the Birmingham district would be greatly augmented. A detailed report on the iron-ore deposits of the district, describing the types of ore and their extent, has been published.In forwarding its mineral conservation policies the United States Bureau of Mines has given some attention to the siliceous ores of this district.The low cost of gravity concentration gives this process first rank in the beneficiation of iron ores. For this reason many experimenters have tried to concentrate the Alabama iron ores on tables. In the face of the early failures a new trial has been made and the results have justified the effort.In this work more attention than formerly has been given to the physical, properties of the ores. The removable siliceous gangue is in the form of oolitic grains which ""shell"" out like corn, leaving the hematite as rich high-grade ""slime"" and as clean granular grains. The ""slime concentrate"" may be recovered by well known desliming processes. The oolitic grains and granular hematite are separated on tables."

May 1, 1929

By C. L. Karr

Researchers at the U.S. Bureau of Mines (USBM) have developed adaptive process control systems in which genetic algorithms (GA's) are used to augment fuzzy logic controllers (FLC's). GA's are search algorithms that rapidly locate near-optimum solutions to a wide spectrum of problems by loosely modeling the search procedures of natural genetics. FLC's are rule-based systems that efficiently manipulate a problem environment by modeling the "rule-of-thumb" strategy used in human decision-making. Together, GA's and FLC's include all of the capabilities necessary to produce powerful, efficient, and robust adaptive control systems. To perform efficiently, such control systems require a control element to manipulate the problem environment, an analysis element to recognize changes in the problem environment, and an adaptive element to adjust to the changes in the problem environment. The control system also employs a computer simulation of the problem environment. Details of an overall adaptive control system are discussed. A specific laboratory acid-base pH system is used to demonstrate the ideas presented; all results are from the physical laboratory system and not from a computer simulation.

Jan 1, 2010

By A. E. Isaacson

Bureau of Mines researchers developed and tested equipment to measure corrosion rates on a commercial scale mill. Bench-scale experiments were designed for duplicating ore grinding conditions closely enough so that realistic rate determinations could be made in laboratory tests. Rates measured in a laboratory system compared favorably with those measured in the field. Cast steel was found to have corrosion rates in a copper mill and laboratory test cell of 22 and 21 mpy, respectively. Corrosion was found to account for less than 5 pct of the total grinding media wear in the operations studied.

Jan 1, 1988

By John Nagy

Tests were conducted in the Experimental coal mine to study some of the factors that should be considered in fighting mine fires and to obtain data on the effectiveness of different types of extinguishing agents. The investigation was confined to class "A" fires in a zone 20 feet long, involving coal burning on the floor, on the floor and ribs, and on the floor, ribs, and roof of the mine entry. It was determined that the time elapsed between ignition and attack of the fire is very important. A fire in the early stages was found to be controlled more easily and quickly than a similar fire that had burned longer. It was also found that, under suitable conditions, a fire in the floor, ribs, and roof develops very rapidly and consequently might spread over a considerable area if not brought under control quickly. The ventilating current affects fire-controlling operations markedly. Attack in intake or fresh air is highly advantageous, the chief inconvenience being the radiant heat from the fire. Attack in direct return air was impossible for the fires tested in this investigation, because of the high temperature. Universal-type gas masks for noxious gases and smoke offered no protection against the intense heat. Approach to a fire in the return air behind a water-fog curtain is not feasible unless the direction of air flow can be reversed. In one" test fresh air was carried to the fire area with a line brattice. Although the entire controlling operation was in fresh air and masks were not necessary, it was considerably more difficult to control the fire than when a similar fire was attacked in intake air.

Jan 1, 1950

By M. L. Whisman

The Bureau of Mines developed a radiotracer method for detecting the contribution of selected components and additives to thermally induce deposits of turbine aircraft fuels. Fuels were examined before and after 52 weeks of storage at 130° F. Of particular concern was the influence of aromatic hydrocarbon fuel constituents on thermal-stability quality of jet fuels during storage. A microfuel coker test apparatus was used to thermally stress the test fuels and blends, and the resultant contribution to deposits of selected fuel components, labeled with carbon-14, was determined by radioactive-counting techniques. Ninety-one blends of five test fuels with carbon-14-labeled fuel additives or components were prepared, tested, stored for 52 weeks at 130° F, and reanalyzed for deposit-forming tendency. These additives included two anti-oxidants, a metal deactivator, and a corrosion inhibitor. Of the labeled hydrocarbon fuel systems studied, the greatest reaction was observed in blends containing methyl-and ethyl-substituted indenes. Other aromatic types also showed some contribution to the deposits. Three of the additives showed a marked tendency to degrade and react during storage and thermal stress. A cresol antioxidant, however, barely contributed to deposit formation. Oleic acid interacted with cadmium present in aircraft fuel systems and produced deleterious effects upon the thermal-stability quality of the fuel.

Jan 1, 1971