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By John Zetterstrom

Increased activity in the beneficiation of taconite, particularly the magnetic variety, has shown the need for more information on the rate of oxidation of magnetite to hematite. This oxidation occurs in the pelletizing step of the beneficiation process. Magnetic taconite is an intimate association of magnetite and a siliceous gangue. It must be ground to approximately 70 to 30 percent minus 325 mesh to liberate the magnetite from the gangue. With sufficient liberation, magnetic concentration will yield a product high enough in iron and low enough in silica for blast-furnace use. The magnetic concentrate must be agglomerated before it can be used in a blast furnace. Agglomeration is the general term applied to all methods of compacting or consolidating fine iron-oxide materials, sintering and pelletizing being the two most common methods. Sintering is clone on a Dwight-Lloyd or Greenawalt sintering machine. Pelletizing consists of balling fine, moist oxide in a rotating drum, followed by baking at .a temperature below that of incipient fusion to develop a permanent bond within each pellet. The magnetic concentrate from taconite is too fine for good sintering practice but fine enough for good pelletizing practice.

Jan 1, 1950

By Robert W. Ageton

Optimal planning for mining the deep, lead-zinc-silver deposits of the Coeur d'Alene mining district, Shoshone County, Idaho, could be facilitated by a knowledge of the magnitude and direction of the pressure acting in the virgin rock. The distribution of primary stresses should be considered in order to prevent possibly destructive mining-induced stress concentrations. This particular investigation was concerned with determining stress in a zone 4,000 feet below the surface and known to be ender stress concentrations due to mining operations. Disking of the stress-relief cores obtained in a vertical down hole permitted qualitative evaluation from visual observations; the results indicate that a high lateral stress existed at the time the measurements were made. Stress-ellipsoid determinations gave a compressive principal stress of -13,000 psi oriented about N 45° W and nearly horizontal, a compressive principal stress of -11,000 psi oriented about S 45° W and abut 60° off the vertical pointing away from the vein, and a compressive principal stress -5 -7,000 psi oriented N 45° E and about 60° off the vertical, pointing toward the vein. Subsequent to the overcoring stress-relief drilling, a rock burst occurred about 100 feet northwest of the test site.

Jan 1, 1967

By Harry Freund, Kenneth H. Hammill, Francis C. Bissonnette

"Gallic acid is a sensitive, stable, colorimetric reagent for the determination of tantalum in the range of 2 to 40 µ g.Ta/ml. The method consists of the fusion of tantalum oxide with potassium pyrosulfate and solution of the cooled melt in saturated ammonium oxalate, followed by development of a yellow complex with an ethanolic solution of gallic acid. The tantalum-gallic acid complex absorbs over a broad region in the blue and near ultraviolet. Adverse effects due to interfering ions and solution conditions, such as oxalate concentration and pH, can be minimized by a suitable choice of wave length.by a suitable choice of wave length.A new and sensitive colorimetric method is provided that has been used successfully at the Northwest Electrodevelopment Laboratory of the Federal Bureau of Mines for determining minor amounts of tantalum.INTRODUCTIONThe development of corrosion-resistant alloys at the Northwest Electrodevelopment Laboratory prompted a review of the analytical chemistry of columbium (niobium) and tantahnn. Not only are these elements difficult to determine in small amounts, but tantalum especially lacks both sensitive and characteristic color reactions. Various phenolic compounds have been suggested as colorimetric reagents for tantalum, Quentin and Wagner (10, p. 24B) 1/ recommend the use of tannin. The use of pyrogallol was suggested originally by Krivoshlykov (6, pp. 59-60), whose method recently has been subject to a number of modifications (3, pp. 249-254; 5, pp. 1340-1344; 1, pp. 1803-18oi; 4, pp. 345-350). The yellow coloration produced by pyrocatechol in an oxalate solution containing tantalum may also be used to estimate tantalum ( 11, pp, ll-1-4-148) . The use of hydrogen peroxide has been recommended also (7, pp. 164-165; 9, pp. 926-931).Aside from a lack of specificity and sensitivity, the major failing of phenolic reagents is their susceptibility to air oxidation. The oxidation products are highly colored and absorb in the same spectral region as the tantalum complex. Holding reductants are not completely satisfactory in minimizing this effect. Increasing the acidity, while retarding the oxidation, has an adverse effect on the tantalum sensitivity."

Sep 1, 1956

By G. D. Jermain

The Bureau of Mines investigated the Gypsum-Camel deposit on Iyoukeen Cove Chichagof Island, Southeastern Alaska, from April 21 to August 26, 1948, as A part of the United States Department of the Interior program for developing an Alaskan construction industry. As gypsum is one of the components necessary for the manufacture of cement and one of the raw materials for plaster and plaster-board products, it is desirable to locate and develop a readily accessible deposit of gypsum in Alaska. In 1928, B. D. Stewart of the Territorial Department of Mines surveyed the gypsum deposits at Iyoukeen Cove, and during the summer of 1946 George M. Flint, Jr., and Edward H. Cobb of the Federal Geological Survey examined and mapped the old workings at Gypsum Creek and the prospect at Iyoukeen Cove. Both the Territorial Department of Mines and the Federal Geological Survey recommended the Gypsum-Camel prospect as warranting a diamond-drilling program by the Bureau of Mines. The Bureau of Mines project consisted of cleaning out and sampling, the old underground workings and diamond drilling from the surface to ascertain the lateral extensions of the deposit.

Jan 1, 1952

By F. C. Gibson

An electrical method for the continuous determination of propagation velocities in opaque, confined explosives, and propellants is described. A resistance element imbedded in the reactive material generates electrical signals that are displayed oscillographically and indicate the position and progress of a reactive zone associated with progress of a reactive zone associated with burning or detonation. The method is applicable to both solids and liquids.

Jan 1, 1963

By A. Wahab Khair, S. Jung

"This paper deals with the fracturing process of laterally confined blocks of coal subjected to impact indentation. During the test, blocks of coal with approximate dimensions of 10 in. x 10 in. x 6 in. were laterally confined to predetermined equivalent in-situ stresses and then subjected to an impact indentation by dropping coal cutting bits (various shapes) attached to a known weight from a known height. During the test a number of parameters, namely surface strains (using strain gages), penetration depth (using L.V.D.T.) and acoustic emission characteristics were measured. After the test, the fractured surfaces were photographed with the aid of a camera attached to a microscope. The fracture, its intensity and extended zone within the coal blocks were mapped using sonic techniques. By correlating measured parameters, fractured zones under a given set of test parameters were identified and characterized.INTRODUCTION To improve the understanding of basic failure mechanisms in coal cutting, a better knowledge of fracture and crack regions caused by the indentation in coal is needed. This study reports the detailed experimental procedure used in fracture analysis of indentation experiments on coal specimens using the Acoustic Emission (A.E. hereafter) and sonic techniques. The relationship between microcracking and the inelastic deformation of rock was confirmed by a series of experiments in which the A. E. generated by the cracking in the rock specimen were recorded and the number of events were compared to the strain measurement. (Scholz, 1967).According to fracture mechanism theory, crack initiation in brittle materials such as rocks begins from ""flaws"" either pre-existing or induced by the indentation process itself. Rocks are pervaded by natural cracks and pores, from which numerous possibilities for crack initiation arise (Lindquist, Lai and Alm, 1984)."

Jan 1, 1989

By Charles A. Seitz

This Bureau of Mines report describes an automatic and continuous transducer-drift compensator. The compensator formed a part of the instrumentation used to indicate the saturation by hydrogen of a cryogenic, adsorption column. It has a variable delayed-response characteristic and will respond only to signals having rise times faster than component drift times. Zero drift due to varying ambient conditions and component aging is nullified. Equations relating the output as a function of the input signal are given.

Jan 1, 1981

By R. V. Mrazek

The heat of formation of vanadium trichloride was determined at 298.15° K. Measurements were made in a solution calorimeter in which an aqueous hydrochloric acid-potassium dichromate solvent was employed. Data are presented for the heats of solution of vanadium trichloride and the vanadium trioxide "backup" compound, and for appropriate dilution reactions needed to preserve stoichiometry. The resulting heat of formation of vanadium trichioride (VCI3) at 298.15° K was found to be ?H°298.15° K = -138.89 ±0.37 kcal/g mole.

Jan 1, 1968

By S. R. B. Cooke, J. Bruce Clemmer, F. P. Diener

"The limestone deposit utilized by one of the plants of the Universal Atlas Cement Co. is covered in part by a stratum of cherty limestone. If this overlying deposit could be utilized by removing the excess of chert economically, quarry costs could be reduced and the amount of rock economically available would be increased greatly. On account of the distribution of flint and limestone, a product fairly free of flint can be obtained until the quarry face is about 50 or 55 feet high. As the face is worked farther back into the hill, the comparatively clean stone is overlain with a constantly increasing amount of high-flint limestone. If this flint remained with the limestone, there would be a prohititively high silica ratio in the finished cement; if the flinty layer were removed as overburden a very large tonnage would be handled and much good stone lost. Consequently it was felt that means should be devised for separating the flint from the limestone after it reaches the plant.The investigation was undertaken by the Mississippi Valley Experiment Station of the United States Bureau of Mines in cooperation with the Universal Atlas Cement Co. and the Missouri School of Mines and Metallurgy, Rolla, Mo.CONSIDERATION OF PROCESSESMany schemes for the separation of Minerals are based on differences in the specific gravities of the minerals to be separated. In this case the flint has a specific gravity of approximately 2.62 while the limestone averages about 2.70. This differential is not large enough to permit separation by any method based on specific gravity. Furthermore, all the limestone particles in any given sample are not alike; usually about 10 percent of them have a specific gravity the same as, or lower than, the flint."

Mar 1, 1935

By M. M. Fine

"Button" type ore from the Cason mine, Batesville, Ark., can be up-graded to plus-40-percent manganese by mineral-dressing procedures. A simple process including gravity concentration and. magnetic separation yielded more than 50-percent recovery of concentrates containing 38.1 to 40.6 percent manganese. These values in turn could be raised to 41.4 and 42.8 percent, respectively, upon sintering to conform to size specifications. The Bureau of Mines in the past has surveyed and tested many manganese ores and prospects in an endeavor to alleviate the shortage of manganese. The present period of emergency again emphasizes the strategic position of the metal, and manganese investigative work is being stressed to find new ore bodies and to apply newer beneficiation techniques to the known deposits.

Jan 1, 1953

By John L. Miller

The synthetic fluormicas may be divided on the basis of silicon content into tetrasilicic, trisilicic, and disilicic. Properties of lead and barium disilicic fluormicas were determined to characterize these two representative members of the disilicic group. Properties described include unit-cell parameters from X-ray diffraction, optical data, chemical composition, density, melting point, and mechanical and dielectric properties. Both the lead and the barium micas were typically monoclinic; neither was sufficiently cleavable to yield usable mica splittings. Both yielded polycrystalline, machinable ceramics with excellent mechanical and dielectric properties.

Jan 1, 1963

By F. W. Horton

This paper covers the salient features of the occurrence and mining of sheet mica in the United States and the preparation of mica for market; presents the results of a study of the physical properties of domestic and foreign micas, which the author hopes may he of interest to every mica user, as it definitely answers many questions as to the suitability of various minas for particular purposes; and discusses mica-trade conditions and the future outlook for the domestic mica industry. ACKNOWLEDGMENTS The author takes pleasure in acknowledging his indebtedness to J. R. Thoenen, of the United Stator Bureau of Mines, under whose guidance the work reported herein was performed, and to Frank L. Hess, also of the Bureau, for information on the geological and mineralogical characteristics of mica-bearing pegmatites.

Jan 1, 1935

By Fred D. DeVaney

The Mesabi iron district of Minnesota has a potential production of over 50 million tons of iron are 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 in¬tent 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 non well under way than of extension of boundaries by the city block plan of growth.

Jan 1, 1932

By A. J. Forney

A high-Btu gas was made at the Bruceton, Pa., laboratories of the Bureau of Mines to demonstrate the feasibility of using the gas as a nonpolluting fuel for automobiles. The pilot plants at Bruceton were revised to combine the processes of coal gasification, gas purification, and catalytic methanation in one overall system. Tests in the Bureau's test automobiles at Bartlesville, Okla., showed the Synthane gas was less polluting than natural gas.

Jan 1, 1972

By Charles H. Parr

A testing program was conducted to determine the suitability and reliability of adhesives and polycarbonate lenses for extended use in luminaires in mine environments. Polycarbonates were exposed, for periods up to 36 months, to four environments including ultraviolet light, humidity, intermittent water spray, and heat of either 180°F or 407 in various combinations. Rod impact tests on the exposed lens material indicated, that polycarbonate functions well under all 180°F environments and could be used with confidence for periods exceeding the test period, for as long as ten years, with a suit) able safety factor employed in design. The specimens exposed at 240°F showed decreased toughness after 24 months' exposure. Extrapolation of these data was deemed to be risky. A 462-day compatibility test between polycarbonate and six hydraulic fluids was run on stressed PC beams. One fluid caused beam breakage in less than one day, while three caused breakage at intermediate times. Two fluids exhibited essentially no effect on the PC when compared to a control. Epoxy and silicone adhesives were tested as lens adhesives and sealants. Three epoxy combinations tested showed low and erratic failure stresses. A room-temperature-cure silicone adhesive functioned extremely well for time periods up to 36 months and temperatures u2 to 240°F.

Jan 1, 1985

By Eric R. Bauer

The magnitude and rate of advance of an inmine coal squeeze was deter-mined by measuring roof-to-floor convergence on a regular basis. A dial-gage tube extensometer was used to collect data. Using these measurements) Bureau of Mines employees drew contour maps and graphs to show the direction and rate of squeezing. Information on the rate of squeeze advance was used to determine whether steps should be taken to prevent roof and/or floor movement from closing an entire section of the mine and if alteration of mining plans was necessary to prevent further squeeze development. Data analysis revealed that the squeeze was decelerating; thus there was no need to strengthen support in the areas of the mine that were studied. Mining plans were altered, however, as a result of the findings of this investigation.

Jan 1, 1981

By Don M. Coulter

"INTRODUCTION The Margerum bauxite district, in Colbert County, Ala. was investigated in December 1940 and in February 1943 by R. W. Smith of the Bureau of Mines .3/ A geologist of the Federal Geological Survey investigated and mapped the district in the fall of 1942.These preliminary investigations indicated bauxite showings over an area about a mile long by 2,000 feet wide. It was felt that the chances were good for finding one or more large deposits of low- to medium-grade bauxite. The location - within 35 miles of the alumina plant of the Reynolds Metals Co. atLister Hill, Ala. – made it especially attractive. A field office was established in Iuka, Miss., on May 19, 190,, and mineral agreements were executed with four landowners covering 1,146.6 cores.The drilling on the project was done under contract. The power drilling was supplemented by a labor crew that drilled hand-auger holes, where there was little or no gravel overburden, and sampled the old test pits.The Federal Geological Survey, after thorough study of the district, recommended 54 drill holes 4/ to delimit the known deposits and to search for possible extensions. After the drilling started, many of these locations eliminated, and others were changed upon the basis of information gathered from the holes as they were drilled."

Mar 1, 1948

By A. C. Fieldner, S. H. Katz

"Introduction.Recent experiments (Fieldner, A.C., Katz, S.H., Kinney, S.P., and Longfellow, E.S., Poisonous gas from carbon tetrachloride fire extinguishers, Jour. Franklin Institute, October, 1920, pp. 543-565), by the Bureau of Mines have shown that carbon tetrachloride extinguisher liquids when applied to fires produce small quantities of irritating and poisonous gases which may be dangerous in very closely confined spaces where conditions are such that the user can not escape without breathing the fumes. The results of the experiments have been confirmed in an independent investigation by the Underwriters Laboratories (Nuckalls, A.H., Corrosive action and products formed when carbon tetrachloride extinguisher liquids are applied to fires, Nat. Fire Protection Assoc. Quarterly, vol. 14, January, 1921, pp. 221-236) who conducted similar experiments for the purpose of determining the corrosive action of these fumes on metals. Both investigations showed that carbon tetrachloride vapor, hydrochloric acid gas, and phosgene were produced in addition to the ordinary products of combustion, such as smoke, carbon monoxide and carbon dioxide. The Bureau of Mines' tests were made by applying a one-quart extinguisher to a wood fire of excelsior in a gas-tight room of 1000 cubic foot capacity. The glass and metal construction of this chamber limited the experimental fire to very small dimensions. It was, therefore, deemed desirable to make a test on a larger scale in the entry of the Bureau's experimental mine in order to similate more nearly the practical use of carbon tetrachloride and other types of extinguishers in mines.Description of extinguishers.Two series of tests were made under identical conditions on different days. Commercial carbon tetrachloride extinguishers were used in the first series of tests and ""foamite firefoam"" extinguishers in the second series of tests."

Jun 1, 1921

By K. C. Dean

A flotation method was developed by the Bureau of Mines for concentrating pollucite, a cesium-aluminum-silicate mineral that may contain from 20 to 40 percent cesium oxide. Separation of the pollucite from three typical ores was achieved by froth flotation of the associated micas, feldspars, and other gangue minerals, using sulfuric and hydrofluoric acids and a cationic-type collector. A low-tenor, 8 percent cesium ore from Maine was upgraded to 20 percent cesium with recovery of 87 percent of the cesium. Relatively high- grade ores from Canada and Southern Rhodesia were beneficiated at lower ratios of concentration to 28 and 29 percent cesium content respectively with recovery of over 92 percent of the cesium. In addition to concentrating the cesium content of ores, the method also effectively separates cesium from sodium, potassium, and lithium, and in certain ores from rubidium. This is accomplished by selective froth flotation of the alkali metal-bearing gangue minerals such as lepidolite, other micas, and feldspars. Since the alkali metals, especially potassium and rubidium, are difficult to separate chemically or thermally from cesium to prepare high- purity cesium products, separation by physical mans is important.

Jan 1, 1962

By Charles L. Ross

A successful placer mine is being operated by the E. T. Fisher Co. on Rock Creek in the South Pass mining district at Atlantic City, Wyo. About 2,800 cubic yards of gravel is dug daily by a gasoline-driven dragline shovel with a 1 1/4-yard bucket and washed in a movable plant with a gold-dredge trommel and standard-dredge sluice boxes; the total cost is about 12 cents per cubic yard. The gold-bearing gravel occupies a narrow valley between two low ranges, of hills. The ground is covered by brush and willows, which are cleared of in the fall by burning after the leaves have dried. The elevation at the mine is 7,600 feet above sea level.

Jan 1, 1935