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By Elizabeth A. Johnson

The vaporization thermodynamics of the aluminum-silicon carbides Al4SiC4 and Al8SiC7 were studied by the Bureau of Mines over the temperature range of approximately 1,500 to 1,700 K. Vapor pressures were measured by a Knudsen effusion-mass spectrometry technique in which powdered samples were effused from graphite crucibles through small orifices. For each compound, a total of six orifice diameters was tested to verify equilibrium within the cell. Aluminum, mass number 27, was the only vapor species detected over the range 4 to 200 amu. Experimental results are based on the following equations for incongruent decomposition: A14SiC4(cr) - 4A1(g) + SiC(a,hex) + 3C(gr); Al8SiC7(cr) - 8A1(g) + SiC(a,hex) + 6C(gr). The observed vapor pressure-temperature relationships determined with a cell orifice area of 2.0 x 10-3 cm2 for Al4SiC4 and 1.81 x 10-3 cm2 for A18SiC7 are the following: Log P - (-18,682/T) + 12.476, for Al4SiC4 (1,550 to 1,643 K) and Log P = (-19,308/T) + 12.421, for Al8SiC7 (1,526 to 1,784 K), with P in pascals and T in kelvins. Third-law analysis of the data provided the following heats of formation: A14SiC4 ?H at 298.15 K - -50.0 kcal/mol and A18SiC7 ?H at 298.15 K - -92.1 kcal/mol.

Jan 1, 2011

By Martin Hertzberg

The concept of limit burning velocities is used to formulate a quantitative theory of flammability limits. Competing processes dissipate power from a combustion wave and quench propagation at some characteristically low limit velocity. There are four competing processes and one complication: (a) Free, buoyant convection, (b) conductive-convective wall losses, (c) radiation, (d) selective, diffusional demixing (the complication), and (e) flow gradient effects (flame stretch). These complexities are unraveled by creating an idealization that is initially freed from these competing processes. The ideal serves as a standard, and its burning velocity (Su), ideal is a unique function of the initial thermodynamic variables of state. By adding each process individually, it is possible to evaluate their significance, quantitatively, in terms of a limit velocity (Su)a , b , c , or e , and to explore the nature of their cooperative interactions. The larger the limit velocity, the more significant the process. The apparently diverse observations of flammability behavior are readily unified within this simple, conceptual framework.

Jan 1, 1976

By Will H. Coghill, Fred D. DeVaney

"INTRODUCTION The Mesabi iron district of Minnesota has a potential production of over 50 million tons of iron ore annually. The large shipments of ore each year are gradually depleting the reserves, and if the present rate of production is to be maintained there must be a growth in the present available ore supply.Growth is a natural course. The growth of a city may be affected by the addition of city blocks or by the improvement of utilities necessary for its betterment, these may go on in the order named or concurrently. The city-block type of growth of the Mesabi has been tremendous, and the ""betterment"" type has followed in due course. Probably the former has reached its limit, and if so, more time will be allotted to the latter. It is not the intent of this paper to present either a eulogy of the wonderful mining methods or a history of the milling, but it is pertinent to say that if the lean-ore area continues to produce, the continuance will be more the result of further improvement of milling methods now well under way than of extension of boundaries by the city block plan of growth.In an examination of the western end of the Mesabi district one finds sludge basins containing millions of tons of millable ore rejected by washing plants which were built for economy in operating cost and with little thought of conservation, and rich tailings piles of jigging plant rejects. In addition, there is an appreciable tonnage of bawl rake pro-ducts so low-grade that it requires mixing with the best ore of the district to make it merchantable.Any of these three products is a source of additional reserves, but gangue must be removed before the products will comply with blast-furnace stipulations. All investigators are agreed that to effect this separation comminution must be fine enough for liberation, but beyond this point opinions diverge; some would seek new processes, while others adhere to methods and machines developed in other mining districts.In the investigation by the Mississippi Valley Experiment Station of the United States Bureau of Mines working in conjunction with the Missouri School of Mines and Metallurgy,Rolla, Mo., the latter course has been followed. Attention was first given to the sludge basins mentioned. From their contents good grades of concentrates were made and the results published 4 later commercial-scale tests were made in a pilot plant of 10 tables, and the laboratory results were confirmed, The tailings from jigging plants are high in iron, and a study of their possible retreatment showed that if they are recrushed, high recoveries of acceptable grade may be expected. The results will be published later."

Apr 1, 1932

USBM Contract H0133045 consists of the design, build and test of 50 waveform generators. The waveform generator is a small ULF transmitter operating in the 1 to 3 KHz frequency range for the purpose of locating trapped miners during a mine disaster. This contract provided for the design, test, and building of 50 waveform generators using a discrete component construction with an option of using hybrid construction techniques within 105 days after the effective date of the contract. Because of large quantity economic considerations, this option was not initiated. Two engineering models were designed, constructed and tested and 50 final production units were fabricated using discrete construction. Complete documentation is supplied under a separate package which includes final schematics, parts list, layout information, equipment specification, production test procedures and qualification test procedures. Ten units have been delivered to the USBM. The remaining 40 units are being retained for packaging under contract H0242010 Transmitter Package and Receivers.

Jan 1, 1974

By J. A. Herdlick

The Star mine, near Neihart, Cascade County, Mont., has been in continuous operation since the construction of a 50-ton bulk flotation mill in 1939. The mine was examined by G. N. Bennett, an engineer of the Bureau of Mines, in November 1942. At that time the life of the operation appeared to be limited and a program of crosscutting and core drilling were recommended. The program had as its objective the investigation of a promising undeveloped area lying west of the Star vein and, if possible, the development of enough reserves in this area to insure continuous operation during the war emergency. Development of additional reserves would then justify necessary changes in the mill in order to eliminate the heavy penalties imposed for excess zinc in the bulk concentrates. The Bureau of Mines work began in February 1944 and was completed in September 1944. The project was started by Wilder R. Brinton and continued by Thomas W. Oster, mining engineers in the Bureau's Montana district office. Beneficiation tests on are and concentrates were made after completion of the underground work. This report presents the factual data obtained during all phases of the Bureau's investigation.

Jan 1, 1949

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

The Bureau of Mines, U.S. Department of the Interior, devised a flotation technique for upgrading chromite in chromium ores and gravity concentrates. The technique consisted of cationic flotation of chromite from a slime-free pulp acidified to pH 2.5 or lower using H2S04 modifier. Flotation results showed that ore containing serpentine as the primary gangue mineral was more amenable to concentration by this technique than ore containing the readily floatable olivine as the primary gangue mineral. Rougher flotation of a chromite ore containing abundant serpertine increased the grade form 19 to 41 percent Cra03 at a chromite recovery of 89.6 percent. Rougher flotation of ore containing abundant olivine upgraded the chromite from 23.4 to 29.6 percent Cr203 at a recovery of 89.4 percent. The technique was also applied to chromite gravity concentrates to further upgrade chromite and to reject silicates. Flotation of a gravity concentrate containing 40.9 percent Cr203 and 4.4 percent SiO2 recovered 90 percent of the chromite in cleaner products containing 44.9 percent Cr203 and 0.63 percent Si02. The combined recovery by gravity and flotation was 87 percent. An economic evaluation of this technique will be undertaken to deter-mine its feasibility for commercial use.

Jan 1, 1980

By Lewis M. McNay

Description of methods employed and cost data are given for surface-mined land reclamation in Moraine State Park, Butler County, Pa. This project was conducted under the authority of the Appalachian Regional Development Act; a total of 177 acres of land was rehabilitated for specific land use purposes. The use of large equipment expedited the project work, and similar results could be anticipated on similar reclamation programs.

Jan 1, 1970

By Earl L. Hastings

Although the principal market for diatomite in the United States is in the East,4 production of the material is presently restricted to the West, because the deposits are larger, mining costs are cheaper, and the quality of product is better than that obtained from other domestic deposits. However, Tallahatta diatomite, occurring in Choctaw and Clarke Counties, Ala., has a freight rate advantage, which should encourage competition for those market that are now being supplied with the purer diatomites from the western deposits. For this reason, diatomite occurrences in the Tallahatta formation were examined by the Bureau of Mines and physical properties of samples from the deposit were determined to obtain additional data for use by any potential producer who wished to evaluate the material for its commercial possibilities. In 1894 K. M. Cunningham5 found that the buhrstone formation (now known as the Tallahatta formation) contained "siliceous shells of marine diatoms, radiolaria and foraminifera, thus being rather of the nature of tripoli or diatomaceous earth than of a true clay." Cooke6 and Semmes7 also reported the Tallahatta formation to be composed principally of diatomaceous earth with accompanying beds of sand, clay, and sandstone.

Jan 1, 1963

By P. A. Wasson

The investigation described in this publication was conducted by the Bureau of Mines to determine the effectiveness of the anionic silica flotation method on goethitic iron-bearing materials from the Cuyuna Range, Minn. Samples used in this investigation were a composite of drill core from 13 holes, and 3 samples from lean ore stockpiles. These samples are believed to be typical of the mineralization occurring in an area with a potential reserve of several million tans of submarginal iron ore. Results from batch tests showed that the iron-bearing minerals could be effectively concentrated by flotation removal of the siliceous gangue. The drill hole composite yielded laboratory flotation concentrates from locked tests containing 56.8 percent Fe and 6.1 percent silica, with an accompanying iron unit recovery of 94.2 percent. Concentrates containing 52.4 to 53.7 percent Fe also were produced from the lean ore stockpile materials; corresponging iron recoveries ranged from 71 to 79 percent in the batch tests, with the possibility remaining for additional recovery of iron from the middlings.

Jan 1, 1963

By Kenneth M. Earl

In its investigation of deposits of strategic minerals, the Bureau of Mines did same development drilling at the Perkiomen Creek deposits, 5 miles east of Phoenixville, Pa. This area was the center of much copper mining from 1851 to 1858. The most productive vein was the Perkiomen-Ecton mines, owned by the Perkiomen Consolidated Mining CQ. The mines were closed in 1858, and no further production has been recorded. The Perkiomen-Ecton vein ranges in thickness from 2 to 19 feet. The principal mineral of value is chalcopyrite, with minor amounts of galena and sphalerite. No definite record was found as to the grade of ore min d. It was reported that 617 tons of 18-percent copper are obtained by hand sorting 12,200 tons of mine-run ore was shipped in 1851-1852. To cut the vein below the old mine workings, the Bureau of Mines diamond-drilled five holes aggregating 2,216.2 feet. The vein, where intercepted by drilling, carried narrow stringers of copper, lead, and zinc minerals.

Jan 1, 1950

By D. R. Mathews

The solubility of carbon in electrorefined vanadium was determined to be approximately 0.27 wt pct at the eutectic temperature 1,650° C and 0.03 wt pct at 700° C. The tensile strength and hardness of vanadium increased with car-bon content to the solubility limit, but this effect was small, probably because of the narrow solubility range. Between the solubility limit and 0.3 weight-percent carbon, the second phase had essentially no strengthening effect in vanadium. The second phase, observed metallographically at the grain boundaries and within the grains, was shown by autoradiography to contain high-carbon concentrations. This second phase was identified as VgC by X-ray analysis. The VgC in the grain boundaries contributed largely to the poor cold-and-hot workability of vanadium-carbon alloys. Increased concentrations of V2C occurred at the grain boundaries of the high-carbon alloy ingots as a result of homogenization at 1,600° C for 1 hour. Alloy ingots containing more than 0.36 wt pet carbon (a calculated 2.9 wt pct VaC) following homogenization, cracked severely and failed by intergranular fracture upon swaging at 900° C.

Jan 1, 1965

By John R. Reigart

The Tri-State district, as its name indicates, is composed of portions of three States, the southeastern corner of Kansas, the northeastern corner of Oklahoma, and an adjacent strip of Missouri east of these portions of Kansas and Oklahoma. An area approximately 40 miles long in a northeasterly-southwesterly direction, and 30 miles wide at right angles thereto, containing minable occurrences of ore at widely scattered locations, comprises the district. However, what has been and is the main productive area, is a strip about 35 miles long and 10 miles wide, which begins at Miami, Okla., as its southern extremity and runs in a northeasterly direction through Commerce, Picher, and Hockerville, Okla., Baxter Springs and Galena, Kans., and Joplin, Webb City-Carterville and Carthage, Mo. Almost the entire present production comes from the area between Commerce and Baxter Springs.

Jan 1, 1932

By C. P. Bowie, George L. Gates

"INTRODUCTION Experience in drilling oil and gas wells has shown that the voidance of blow-outs, twist-offs, fishing jobs, loss of circulation, and heaving and caving of shale formations into the drill hole depends largely on how well the drilling-mud fluid serves its purpose. A possible method for the control of the drilling fluids may be seen from a study of the relation between the particle-size distribution and some of the important drilling-fluid properties, such as the ability to build quickly a relatively impervious mud sheath on the wall of the hole in the porous formations penetrated by the bit during drilling operations. In a wartime economy, which urgently requires conservation of steel, proper functioning of the drilling fluid is particularly important because, as Parks 4/ has stated, intelligent use of good drilling fluids makes possible drilling of wells for thousands of feet in open holes without the necessity of setting protective strings of casing to control the movement of salt water, gas, and troublesome formations into the borehole; consequently, especially in deep wells, of proper drilling fluids materially reduces the need for casing and lowers the cost of drilling and completing the wells."

May 1, 1942

By Israel Liebman

The Bureau of Mines developed three types of passive water barriers for suppressing slow-moving coal dust explosions. One type is a modification of a conventional tub barrier and depends on the dynamic pressure generated ahead of an explosion to tilt the tub to release its water and suppress the explosion. The other two barriers operate in response to an increase in static pressure developed ahead of the explosion. Tests indicate the first barrier begins to release its water at air speeds as low as 50 ft/sec, and the second and third barriers will operate at a rise in static pressure as little as 0.5 psi. All three barriers were found to be effective in suppressing coal dust explosions propagating at speeds as low as 100 ft/sec. A plan is described for installing a water barrier in a working mine on a trial basis.

Jan 1, 1976

By F. W. Wood

A program of research was conducted by the Bureau of Mines to investigate anomalies in electrical-discharge behavior during consumable-electrode arc melting of titanium and to study the effects of these irregularities on arc-furnace explosions. A major effort was devoted to an experimental survey of arc behavior and a qualitative definition of discharge phenomena.3/ An important conclusion was that the "glow" of industrial arc-melting terminology is not a glow discharge but a skittering arc in a displaced position. The conditions that permit displaced skittering were tentatively defined. The displaced skittering arcs tended to damage melting crucibles in two ways, and details of possible mechanisms leading to crucible rupture and explosive reactions have been proposed accordingly. However, no acceptable means of preventing crucible damage was discovered.

Jan 1, 1961

By Richard D. Miller

The helium resources base of the United States was estimated by the Bureau of Mines to be 1,070 Bcf as of January 1, 1985. These resources are divided into four categories in decreasing degree of assurance of their existence: (1) helium in storage and in proved natural gas reserves, 280 Bcf, (2) helium in probable natural gas resources, estimated at 243 Bcf, (3) helium in possible natural gas resources, estimated to be 287 Bcf, and (4) helium in speculative natural gas resources, which makes up the remaining 260 Bcf. These helium resources are further divided into depleting, non-depleting, and stored classifications. The depleting resources are those associated with natural gasfields that are, or will be, produced for the natural gas they contain. Almost all of the helium in potential (probable, possible, and speculative) natural gas resources is included in this classification. These depleting resources are estimated to contain 900 Bcf of the total helium resource base. Helium resources contained in nondepleting natural gas resources, those in shut-in, abandoned, or otherwise nonproducing natural gasfields, are estimated to total 133 Bcf. There is 37 Bcf of helium in storage in the Federal Government-owned Cliffside Gas Field near Amarillo, TX.

Jan 1, 1987

By H. Winkelmann

The author, who himself has worked inn the field with various types of torsion balances, expresses in the article his experience with the recently marketed Haff-Torsion-Balance. The advantages of practical work with Haff?s s torsion balance as compared with other types are mentioned. In spite of low weight and corresponding small dimensions (Model M = 23.5 kg., Model Al = 11.5 kg.) the sensitiveness is not less than that in the largest instruments. It is at 1.10-9, which is proved by calculations. A comparison with the corresponding values of other types of torsion balances (Eötvös, Askania, Gepege) is given. The mechanical features of the instrument are briefly described, and the balance is illustrated by a, cross section of it. -- W. Ayvazoglou. DETERMINATION OF THE ELEMENTS OF THE MAGNETIC AND GRAVITATIONAL FIELDS INDUCED BY AN INFINITELY LONG HOMOGENEOUS CYLINDER By G. A. Gamburzeff Gerlands Beiträge zur Geophysik, Band 19, Heft 2/3 Leipzig, 1928, pp. 210-230. The present work is a. contribution to the quastion of the reason for the magnetic and gravitational anomalies in the government of Kursk (Russia).

Jan 1, 1929

By Deborah A. Kramer

This Bureau of Mines report presents a cost estimate of the Bayer process, which is used for virtually all cell-grade alumina production. The report will serve as a reference point to determine the economic merits of processes that have evolved from Bureau of Mines investigations on technology for producing alumina from domestic nonbauxitic raw materials. The Bayer process involves dissolving the alumina present in bauxite in a caustic solution at high temperature and pressure. After the un- dissolved impurities are removed, the solution is seeded to produce an alumina trihydrate precipitate. This precipitate is filtered, washed, and calcined to produce the cell-grade alumina product. This cost estimate is for a plant producing 1 million tons of alumina per year. The estimated operating cost is approximately $250 per ton of alumina.

Jan 1, 1983

By Robert W. Ageton

The Bureau of Mines investigated the in situ vertical component of the rock stress in the rib of the haulage drift on the 6100-level of the Star mine, Burke, Idaho, using the flatjack and borehole deformation methods. The estimate of the vertical component of stress about 2 feet into the rib at a station along the haulage drift on the 6100-level of the Star mine by the flatjack method is approximately 5,875 psi, whereas the borehole deformation procedure at this station yielded a value of 5,500 psi for the same depth into the rib. The test zone is approximately 5,625 feet below the surface.No attempt was made to extrapolate stress estimates beyond the depth of the flatjack installation.

Jan 1, 1967