Search Documents

By Richard F. Hewlett

Numerous populations of assays have been simulated for a range of assay values representative of low-grade mineral deposits to facilitate the study of problems encountered in evaluating these deposits. Analysis of these simulated populations of assays (obtained by using statistical probability models for the simulation) makes possible the quantification of the effects of (1) various composite assay intervals, (2) ore reserve computational methods, (3) uneven assay intervals, and (4) various cutoff grades on both the precision and the accuracy of the estimated average grade and tonnage of ore.

Jan 1, 1964

By H. V. Makar

The Bureau of Mines successfully demonstrated, on a pilot plant scale, a sodium sulfate (Na2S04) refining process for removal of copper from molten ferrous scrap. Previous tests established technical feasibility on a bench scale for achieving low copper concentrations and determining the principal factors controlling process efficiency. The pilot plant study involved a 1-ton arc furnace for melting ferrous scrap and a 1-1/2-ton treatment ladle. Results of these tests showed that copper removals obtained in laboratory tests (approximately 40 relative percent copper removal with 10 weight-percent surface addition of sodium sulfate) could be achieved on the pilot plant scale when excess carbon was added with the sodium sulfate compacts. Data were obtained on temperature losses and carbon consumption related to Na2SO4 treatment.

Jan 1, 1974

By A. S. Moore

The Bureau of Mines is doing research and development work on removing acid-gas impurities from synthesis gas made directly from coal. Since conventional gas scrubbers, packed towers and bubble-cap columns, are expensive to construct and difficult to operate with viscous solutions, one aspect of the work was developing a compact, agitated, gas-liquid contactor for use with concentrated absorbents. The efficacy of the agitated contactor for absorbing carbon dioxide in diethanolamine increased with increasing solution rate, turbine speed, diethanolamine concentration, and carbon dioxide concentration in feed gas, and with decreasing liquid-gas ratio. It was unaffected by pressure between 200 and 300 p.s.i.g. and little affected by temperature between 115 and 190° F.

Jan 1, 1961

By C. B. Manula, R. L. Sanford, R. A. Rivell

PART I. FLOW CHARTS

Jan 1, 1974

By Frank E. Cash

Data on the accident experience of the pebble-phosphate industry in Florida for 1930 and 1940 are combined in this report with statistics for the 9-year period 1930-38, inclusive, which were published in Information Circulars 69173/, 69684/, and 71005/. The periodic compilation and publication of such data enable the pebble-phosphate industry, as well as other industries, to consider the relative hazards, compare experience, and thereby help to prevent accidents. ACKOWLEDGMENTS Accident data were furnished by the following operating companies: Amalgamated Phosphate Co., Brewster; American Agricultural Chemical Co., Pierce; Coronet Phosphate Co., Plant City; International Agricultural Corporation, Mulberry; Phosphate Mining Co., Nichols; southern Phosphate Corporation, Bartow; and Swift & Co., Fertilizer Works, Bartow.

Jan 1, 1941

By Frank E. Cash

"INTRODUCTION The iron—ore ranges in the Lake Superior district are the Marquette in Michigan, Menominee and Gogebic in Michigan and Wisconsin, and the Cuyuna, Mesabi, and Vermilion in Minnesota. These ranges produce about 85 percent of the iron ore mined in the United States. Accident experience in connection with this production is better than that of the regions producing the remaining 15 percent. Production and shipments vary slightly from year to year but closely approximate each other over a period of years.This information circular supplements, continues, and combines the data in Information Circular 7321,2/ including figures of 1944 and 1945.During the 6—year period 1940 to 1945, inclusive, 481,485,475 long tons of iron ore was shipped from the Lake Superior district. 4/ Michigan and Wisconsin shipped 93,787,648 tons, or 19,5 percent of the total, and employed annually an average of approximately 14,300 men; Minnesota shipped 387,697,827 tons, or 80,5 percent, and employed annually an average of approximately 9,300 men. The tons produced per man employed is much greater in Minnesota than in Michigan and Wisconsin, owing to the large open-cut production in Minnesota."

Jul 1, 1947

By R. O. Pynnonen

This circular is a study by the Bureau of Mines of 346 accidents in underground iron-ore mines of the Lake Superior district from June 1949 to August 1954. These accidents caused 354 lost-time injuries, including 28 fatalities and 2 permanent-total disabilities. The accident reports were analyzed by the Bureau to show the causes of injuries and the time charges and unsafe practices or conditions that caused the accidents. Also shown are the times of occurrence, ages of the injured by job classification, and experience of the injured in mines and on the job being performed when hurt. Detailed information is presented on approximately 14 percent of the total number of Lake Superior district underground mine accidents that resulted in lost-time injuries during the period covered. These facts are presented to aid accident-prevention measures in underground mines and as a record for measuring future safety accomplishments.

Jan 1, 1956

By John Ward Smith

Variations in specific gravity of oil retorted from oil shales of the Eocene Green River Formation in northwestern Colorado were evaluated statistically, demonstrating that these variations are very strongly associated with stratigraphic position and less strongly but still significantly associated with geographic location. Specific gravity of oil retorted from these oil shales apparently varies with the carboxyl group content of the oil shale's organic matter. Higher temperatures accompanying increasing depth of burial probably progressively decarboxylated oil shale's organic matter producing the decrease of oil specific gravity associated with deeper stratigraphic position. The geographically associated oil-gravity variations were probably produced by regional variation in the original thickness of late Cenozoic extrusive rocks once overlying the Green River Formation.

Jan 1, 1966

By H. R. Babitzke, H. Kato, M. D. Carver

A number of columbium and tantalum alloys were investigated to determine their suitability for use at elevated temperatures . Columbium-vanadium , tantalum-vanadium , and tantalum-hafnium alloys , and also columbium- 10 wt pct titanium alloys modified with additions of 0.1 to 2 mole pct ZrO2 , TiO2 , ZrB₂ , TiB , ZrC, or TiC were prepared and examined . Workability , tensile properties , and oxidation resistance were tested . Of the columbium alloys studied , the columbium- 12 at . pct vanadium exhibited the best properties ; it compared closely with the columbium- 10 at . pct vanadium alloy studied in a previous investigation.

Jan 1, 1964

By Jack R. Woodyard

Scientists at the U.S. Bureau of Mines are studying iron aluminides as possible substitutes for stainless steels to reduce the Nation's dependence on imported strategic and critical materials. In a Bureau investigation on the mechanical properties of Fe-28Al, it was found that the material's machining properties were significantly improved at slow tool and feed speeds. Machining techniques normally used for brittle materials failed or were costly. Further experiments using a 5-in (12.7-cm) mill cutter with carbide inserts, operating dry at minimum machining speeds, produced visually smooth sample surfaces with no tool damage. As a result of these experiments and a review of published data on hydrogen embrittlement of iron aluminide under tension, non-water-based (e.g., sulfur-based) lubricants were chosen for production machining. Four-flute, 3/4-in (19-mm) carbide end mills were used at slow speed under lubrication. This latter procedure reduced tool wear and breakage by a factor of 2. Machined surfaces and specimen cross sections were analyzed by scanning electron microscopy to detect microcracking. Tensile tests gave the expected yield and ultimate strengths, indicating that no degradation by low-speed machining occurred. This study extends this work to show that the alloy can be machined at higher speeds using high-speed steel end mills, and that water-soluble cutting oil is a suitable lubricant and coolant.

Jan 1, 2010

By Wallace W. Roepke

Research to evaluate the lubricity effects achieved by spraying water on the cutting bit of a mining machine or spraying water on the coal during cutting has shown that neither practice affects cutting forces, as had been believed. However, when water was supplied to the cutting zone axially through the bit at 3,000 to 5,000 psi pressure, tangent'ial cutting forces were reduced an average of 30 pct at a I-in depth of cut while normal bit forces were reduced an average of 65 pct. Lower normal forces mean reduced bit wear, faster advance with greater depth of cut, and fewer coal fines.

Jan 1, 1985

By S. H. Ash

The Pennsylvania anthracite-mining region is the only one in the world of major magnitude. As the deposits of anthracite in the United States are limited virt113.lly to Pennsylvania, the difficulties of this industry have been commonly considered a State rather than a national problem. However, there is also national interest in the conservation and wise utilization of all fuel resources and in the control of interstate waterways. The anthracite industry is confronted with the very se:;-ious :problem of accumu.lation of water in many of the mines. This problem must be solved soon if progressively higr-er mi~ing costs are to be avoided. The water proble~ cannot be solved by the operating compa,nies without State or Federal aid, or both, owing to the magnitude of the work requir~d, diversity of interests of the coal ana surfa.ce ovmerships, hazard to the whole mining community, and interests affec~ed outside the mining region. The cost of abati~ the ever-increasing_surface seepage to mine workings and of handling this seepage once it }3s occurred is beyond the economic resources of most ope~ating ma.'18.gements. The data in this paper giving the high lights of the water problem and indicating what appears to be a step in the right direction are based upon observations made during the past year that the industry desires and believes it is to the npublic interesttr to keep mine workings free of flood end surface waters.

May 1, 1941

By Seth C. Schaefer

The Bureau of Mines investigated the standard Gibbs energies of forma-tion AGfo, for NiCr204 (nickel chromite) and CoCr204 (cobalt chromite). High temperature galvanic cells employing stabilized ZrOz (zirconia) as the solid electrolyte were used to measure the open-circuit potentials for the cell reactions ?

Jan 1, 1986

By G. E. McElroy

When mechanical ventilation is to supersede the natural ventilation of a mine it is desirable to determine what resistance the mine as a whole offers to the flow of air in order to specify properly the limiting duties of a ventilating fan. The relation of pressure to volume of flow for the mine as a whole may be calculated from experimental data, or it may be determined directly by measurements of volume of flow and the natural draft pressures causing flow; but in both methods the determinations are affected by many variables. With the intention of making a practical application of both methods, a small metal mine in process of development at Butte, Mont., was selected by the writers as the object of experiments planned to compare the mine resistances determined by measurements of natural draft and volume of flow with those calculated from experimental data. Four sets of teats were made with natural draft in October, 1925, December, 1925, April, .1926, and September to December, 1926; the last set consisted of a series of weekly observations. DESCRIPTION OF MINE The mine selected for the experiments was a typical vertical shaft metal mine in the development stage. No stoping had been done, and ventilation was confined to shafts, crosscuts, drifts, and raises. Figure 1 is a dia¬grammatic sketch of the main openings. All were timbered with full sets on approximately 5-foot centers. The shaft compartments were 4 by 4.5 feet, and one in each shaft was partly blocked by staggered manway landings. A pump column in the upcast shaft was discharging about 280 gallons a minute of water at 70° F. from the 1,000-foot level. The drifts were slightly sinuous, but the crosscuts were exceptionally straight and uniform in area; both drifts and crosscuts were about 5 by 7 feet in cross section. The raises were composed of vertical sections joined by frequent 450 offsets; each had three 4.5 by 4.5-foot compartments, of which two were plank-lined ore chutes and one was partly

Jan 1, 1928

By N. A. C. Smith

[The beau of Mines made its first survey of motor gasolines sold throughout the United States in 1915, a second in 1917, and a third in April. 1919. These surveys shored that motor gasoline had become notably less volatile during each two-year interval. In order to ascertain whether this change was continuing, it was planned to institute semi-annual surveys, the first of which teas made in January, 1920. Contrary to expectations based on the previous surveys, the average volatility of the gasoline tested at this time was practically identical with that of the average volatility of the gasoline from the same districts in 1919. The next survey, made in July, 1920, showed a very marked decrease in volatility but as it has long been recognized that the volatility of motor gasoline manufactured for sale during the summer months is loss tan that of gasoline made and sold during the winter, part at least of the change was attributed to this factor. The average boiling point of the samples collected in the present survey is 263 degrees Fahrenheit, as compared with 264 a year ago. This shows that the average gasoline marketed at the present time is fully as volatile as that marketed a year ago. There has been, however, a noticeable change in the character of the product: the initial boiling point and 20 per cant point are lower than a year ago, whereas the 90 per cent and end-points are higher, which indicates a greater proportion of gasolines made by blending casing-head, or natural gas-gasoline, and naphtha.]

Jan 1, 1921

By C. G. Storm

Permissible explosives are those that have passed the tests pre- scribed by the Bureau of Mines for explosives intended for use in coal mines, and are therefore recommended by the bureau as suitable for this class of work when used under the prescribed conditions. The tests for permissible explosives and the conditions prescribed for their use are described in Miners' Circular 6 of the Bureau of Mines. Up to June 1, 1915, 168 explosives had been classed as per- missible explosives; 133 of them were then on the bureau's "per- missible list" and 35 had been withdrawn by the manufacturers. In addition to the required physical tests, each explosive is sub- jected to a complete chemical examination in order that its exact composition may be known and also that the composition of future samples of the same explosive collected in the field may be compared with that of the sample which originally passed the bureau's tests, for by such comparison it may be possible to ascertain whether or not the explosive as supplied to the miner is still "permissible." This bulletin is published primarily for the purpose of informing manufacturers of such explosives as to the methods used by the Bureau of Mines in the analysis of samples received for tests to determine their permissibility. Such information may be of value in cases of possible controversy over the results obtained in the analysis of a field sample as compared with those obtained in ana- lyzing the sample originally tested by the bureau. Also, a descrip- tion of the methods used by the Bureau of Mines in the analysis of explosives should be of assistance to the many chemists engaged in similar analytical work.

Jan 1, 1916

By Donald E. Redmon

This Bureau of Mines report reviews injury experience in the metallic mineral industries for 1966-67. For each of the years, 27 tables summarize disabling work injuries by department, source of injury, extent of disability, part of body injured, and nature of injury. Correlative information on employment, worktime, and operating activity is also presented.

Jan 1, 1973

By W. E. Anable

The Bureau of Mines researched methods for recovering copper from cyclone and electrostatic-precipitator dusts of primary copper smelters as part of its program to maximize minerals and metals recovery from primary and secondary domestic resources. Small-scale studies showed that use of 110 pct stoichiometric sulfur and 123 pct stoichiometric carbon, based on producing a 40-pct copper-iron matte, resulted in the recovery of 95 pct of the copper contained in the dust. Typical mattes contained less than 10 pct of the arsenic, 30 pct of the bismuth, and 45 pct of the antimony and tin contained in the dust. Matte was converted to blister copper by injecting up to 200 pct of the stoichiometric oxygen requirement over a period of 2 to 3 hours. Up to 76 pct of the copper contained in the dust was recovered as a crude blister copper containing about 2 pct arsenic, 0.5 pct antimony, and less than 0.1 pet bismuth and tin. A matte-white metal product resulted from carbothermically reducing dust with coal, lime, and silica. Up to 95 pct of the copper was recovered in the combined product.

Jan 1, 1981

By Bertrand L. Johnson

Pure talc is a hydrous magnesium silicate (Mg3Si4010(OH)2). Pyrophyllite, although it resemble: talc in certain physical properties and uses, is a hydrous aluminum silicate (Al2Si4010(OH)2) - like kaolin, except that kaolin has a somewhat different composition (Al2Si205(OH)4) and structure. Soapstone can be considered essentially an impure talc grid when pulverized is used for many of the same purposes as talc. Massive, compact varieties of talc often are called steatite. PROPERTIES Talc and pyrophyllite are characterizes; by their softness (hardness on Mohs' scale, 1) their greasy feel, pearly luster, white color, and perfect basal cleavage. They have similar crystal structures, and this similarity explains the close resemblance of the two minerals in physical acid chemical properties. Talc is a good electrical insulator, resists the action of most acids and alkalies, and has an exceptional heat-retaining capacity. Its specific gravity is about 2.7.

Jan 1, 1939

By C. N. Adams

The purpose of this investigation was to evaluate the physical and mechanical properties of high-purity titanium made by two processes. Sodium-reduced metal with 58 Brinell hardness number (B.h.n.) and electrorefined metal with 60 B.h.n. and 70 B.h.n. were used. Titanium of these hardness levels did not work-harden excessively, and beyond 40 percent cold work the hardening effect was not great. Rapid softening occurred when the metal was annealed at temperature between 300° and 600° C. Full annealing, as determined by property and microstructure studies, was accomplished after 30 minutes at 700° C. A recrystallization diagram is presented which is based on determinations of annealed grain size as a function of rolling reduction and annealing time. For reductions of less than 20 percent, exaggerated grain growth occurred during annealing; for reductions greater than 20 percent, the variation in grain size for each annealing temperature was minor.

Jan 1, 1961