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By S. C. Termes

To help develop the basis for new fine-particle separation methods, the Bureau of Mines has investigated the use of cross-linked starches containing four chelating groups--carboxylate, iminodiacetate, dietha-nolamine, and xanthate--as flocculants for selected metal oxide and hydroxide mineral fines. It was found that those starches capable of interacting with the mineral surface by a chemisorpti,on mechanism (as indicated by zeta potential measurements) produced the highest recover-ies and'grades of the metal oxide or hydroxide when flocculated from a binary mixture with quartz. The effects of pH, dispersing agent, stirring rate, stirring time, and starch dosage on selective flocculation were studied for binary mixtures of hematite and chromite with quartz. Floc strength becomes important in achieving maximum recoveries by mechanical postflocculation separations.

Jan 1, 1985

By Charles B. Kenahan

Application of ultrasonics in the electrolytic deposition of metallic manganese and manganese dioxide from sulfate electrolytes had several effects. Ultrasonics produced finer-grained deposits of electrolytic manganese at all current densities than obtained in normal cell operation, but at high current densities it resulted in less adherent deposits. Ultrasonic radiation did not affect cell voltage or cathode current efficiency. In the electrodeposition of manganese dioxide at 70° C., ultrasonic-; increased the current efficiency and decreased the cell voltage at a current density of 9 amperes per square foot, but it had little effect at current densities above this. The decrease in cell voltage was caused by the depolarizing action of ultrasonics at both anode and cathode. Ultrasonic radiation produced a smooth, glossy, adherent, and pit-free deposit at all current densities and at each temperature. Radiation had no effect on current efficiency or cell voltage at 90° C. Ultrasonics was more effective than conventional agitation in producing all of these effects.

Jan 1, 1962

By R D. Fleming

A single-cylinder research engine was operated on pure hydrocarbons and simple (two-component) mixtures of pure hydrocarbons to study the effect of fuel composition on exhaust emissions from a spark-ignition engine. Used as fuels were three pure hydrocarbons that represented the primary hydrocarbon types present in commercial motor fuels: A paraffin (2,2,4-trimethylpentane), an olefin (2,4,4-trimethylpentene-2), and an aromatic (meta-xylene). The engine was operated at the same equivalence ratio for all of the fuels used in the experiment. Exhaust gas samples were collected and quantitatively analyzed for carbon monoxide, carbon dioxide, hydrogen, nitrogen oxides, aldehydes, and hydrocarbons. Exhaust hydrocarbons were separated and quantitatively measured with a chromatographic system employing a flame-ionization detector. Unknown hydrocarbons and oxygenated materials in the exhaust were identified with a Time-of-Flight mass spectrometer coupled to a chromatographic system. The results of the exhaust gas analyses showed that ethylbenzene, l-methyl-3-ethylbenzene, and l-methyl-3-vinylbenzene were more abundant in the exhausts from either 2,2,4-trimethylpentane--m-xylene or 2,4,4-trimethylpentene-2--m-xylene fuel mixtures than in exhaust produced from m-xylene. Also, the pure 2,4,4-trimethylpentene-2 fuel produced smaller amounts of C2 to C7 olefins in the exhaust than that produced by the pure 2,2,4-trimethylpentane fuel. The exhaust from pure m-xylene fuel contained aromatic hydrocarbons of higher molecular weight than the parent fuel. The amount of total hydrocarbon (moles of exhaust hydrocarbon per mole of fuel used) in the exhaust from the three pure fuels decreased in the following order: 2,2,4-trimethylpentane > 2,4,4-trimethylpentene-2 > m-xylene. The hydrocarbon mole-fractions of unreacted fuel in the exhausts produced from each of the pure fuels were 0.20 for 2,2,4-trimethylpentane, 0.13 for 2,4,4-trimethylpentene-2, and 0.66 for m-xylene.

Jan 1, 1970

By J. E. Tress

The Bureau of Mines has developed a process to utilize waste heat from electric arc steelmaking furnace gases to preheat the ferrous material charged to the furnace. Four heat exchangers were designed, tested, and operated successfully on 1-ton electric arc furnaces. Briquets and pellets were charged continuously, both countercurrent to the hot furnace offgasses and at ambient temperatures. A comparison of the electrical energy consumed in each situation showed that preheating can lower energy requirements as much as 15.6 percent.

Jan 1, 1975

By J. M. Kuchta

The Bureau of Mines used laminar hot air jets of l/8- to 3/4-inch diam-eter to determine the hot gas ignition temperatures of various combustible vapor-air mixtures. The combustibles were n-hexane, n-octane, n-decane, a hydrocarbon jet fuel (JP-6), and an adipate ester aircraft engine oil (MIL-L- 7808). Minimum ignition temperatures occurred at a fuel to air weight ratio of about 0.5 and were not greatly sensitive to variations of fuel concentra¬tion. Moderate variations of jet velocity also had little influence on these ignition temperatures. However, these temperatures decreased with increase in heat source dimensions (jet diameter). The hot gas ignition temperatures of the combustibles were not necessarily much greater than corresponding autoignition and wire ignition temperatures when the size (,F the heat source and the ignition criterion were the same.

Jan 1, 1966

In 2006, a total of 4,573 stone mining operations reported employment to the Mine Safety and Health Administration (MSHA).1 Stone mines comprised 30.7% of all mining operations. ? Mines producing the primary commodity of limestone (crushed and broken) comprised the largest number of operations (n=2,042; 44.7%). ? Stone mining operations were located in all states and territories except Delaware and North Dakota. ? Pennsylvania had the most stone mines (n=368; 8.0%), followed by Texas (n=342; 7.5%).

Jan 1, 2008

By Clarence O. Babcock

ROCK BEHAVIOR has proved of national interest in a variety of fields. The behavior of rock consequent to a nuclear blast was used to detect such blasts, as criteria for the design of underground military defense installations that would resist nuclear blasts, and for judging the feasibility for peaceful uses of nuclear explosives. An obvious peaceful application of nuclear explosives would be for large-scale rock excavation, and plans were presented during the year to improve the present Panama Canal or create a new canal by this method. These plans were based largely on earlier crater tests that demonstrated rock behavior when subjected to a buried nuclear blast. A knowledge of rock behavior under impact was used to evaluate the materials of the moon by means of the geometric configurations visible in the close-up pictures of the moon surface taken by the U.S. rocket Ranger 7. The composition of the moon must be considered in devising methods for taking samples of the surface layers or in designing underground shelters as bases for future explorations of the moon.

Jan 1, 1965

By Carl E. Norman

An investigation of geologic structure on macroscopic, mesoscopic, and microscopic scales was conducted on near-surface igneous and metamorphic rocks in which the existing stress field was determined by in situ methods. A consistent NE-SW orientation of the maximum compressive stress in the horizontal plane at four of five test localities appears due to the intrusion of NW-trending diabase dikes. Structural features at the mesoscopic scale show no consistent directional relationship to determined stress directions. Petrofabric diagrams of open microfractures show preferred orientations, but these are not consistently related to the orientations of larger structural features, such as joints, foliation, or mineralized shear zones. However, at five of six test sites the preferred direction of microfractures occurs nearly perpendicular to the maximum principal stress directions; an anomalous parallel relationship exists at a test site in an intrusive rock body. The results suggest that the open microfracture subfabric may provide a means for gaining information on the directional properties of stress fields. Such information can be obtained from oriented cores taken from holes which exceed the approximate 100-foot depth to which other in situ methods are presently limited.

Jan 1, 1970

By John S. Berber

Olefin and paraffin mixtures (C10-C16 and C10-C22) were separated from low-temperature lignite tar by urea adduction and sulfated to yield secondary alkyl sulfate detergents. The C10 ?C16 secondary alkyl sulfate showed a 99.3 percent biodegradability, and the C10-C22 fraction showed a 96.8 percent biodegradability, exceeding the required standard of 80 percent for the biodegradability of anionic detergents in washing and cleaning compounds. Chlorination of paraffins yielded a detergent of 93.2 to 93.4 percent biodegradability.

Jan 1, 1968

By H. G. Lucas

A feeder screw supplied at constant pressure by a hopper-orifice arrangement was developed for feeding solids in size ranges up to several hundred micrometers at constant flow rates. Performance of the feeder was evaluated by measuring the flow rates obtained with 3-to 7-micrometer coal ash, 70 percent through 200-mesh coal, and minus 325-plus 400-mesh coal ash. Constant feed rates within a few percent of set values were achieved for half-hour periods for the larger particles and for 5-minute periods for the finer particles. Suggestions are given for feedstock preparation and feeder operation for optimum performance.

Jan 1, 1974

These proceedings consist of an overview of the underground metal and nonmetal mina fire protection research currently being conducted by the Bureau of Mines. The following papers address the areas of prompt, reliable fire detection, fire planning and warning, fire suppression, and personnel protection. Selected topics are included here that cover fire protection systems for shafts, underground fueling areas, and mobile underground mining equipment; spontaneous combustion, improved stench, and product-of-combustion fire warning systems; computer-aided ventilation modeling; fire doors; and an investigation of fire hazards in mine timbers. The projects described provide a current documentation of problems being addressed.

Jan 1, 1981

By J. W. Walkiewicz

Studies were conducted by the Bureau of Mines to develop a method for fabricating Sm-Co permanent magnets. This method consisted of arc-melting, crushing and grinding the alloy, alining and pressing the powder, and sintering the green compacts. Results indicated that the optimum composition was 36.7±0.3 weight-percent Sm and 63.3±0.3 weight-percent Co. This composition was obtained by blending together Sm2C07 and SmCo5. The maximum values exper¬imentally obtained were MHC = 27.4 kOe, BHc = 7,510 Oe, Br = 7,810 G, and (BH)max = 15.1 MGOe. The optimum sintering temperatures and grinding times for maximum MHc and (BH)max were determined. Lowering the grinding temperature from 0° C to -60° C resulted in a significant increase of magnetic properties.

Jan 1, 1973

Over and above the technical support arid consulting work described in the preceding Parts of this Volume, ADL staff also provided a wide range of additional technical assistance to the Bureau on an ad hoc basis over the course of the contract, and particularly in 1973. Some of these assignments were on tasks that temporarily assumed a high priority at PMSRC, requiring a fast response, while others were more suited to conventional schedules but on communication and location topics less directly related to those in the preceding Parts. Chapter I briefly describes some of the diverse short-term assignments while Chapters I1through V treat assignments on the other topics. I SHORT-TEXM ASSIGNMENTS A sampling of short-term, fast-response assignments undertaken on mine communications and miner location for PMSRC during 1973 are given below. These assignments included technical reviews, discussions and recommendations related to the theory, experimental data, designs, and hardware implementation of experimental CW and pulse miner location EM transmitters; preparation of technical performance specifications for a miniaturized preproduction prototype CW electromagnetic location transmitter; review of specifications for a seismic signal detection experimental study; participation in technical discussions and experiments with PMSRC and equipment suppliers regarding the UHF radio/radiax-cable communications installation in the Bruceton mine; participation in an informal conference to discuss mine communication and monitoring needs and preferences with representatives of the Bureau, mine operators, and equipment manufacturers; participation in technical discussions with representatives of a U.S. mine operator and CERCHAR* concerning the characterization of faults on trolley lines and means of improving their rapid detection;** recommendation of simple signal, noise, and ground fault measurements on mine phone lines; review of an inexpensive automatic telephone dialer; preliminary discussions regarding the feasibility of adapting and assembling a collection of available telephone industry carrier equipment for installation and test in an operating coal mine; evaluation of a proposed call alert mine paging system; review of hardware designs and future experiments for a mine communication sled; design critique of a proposed six-channel narrow-band FM voice modem for carrier communication on the mine phone line; preparation of technical performance

Jan 1, 1974

By Samuel P. Harteis, Eric S. Weiss

The National Mining Association and the Mine Safety and Health Administration requested that the National Institute for Occupational Safety and Health (NIOSH) conduct full-scale evaluations of a recently developed carbon fiber-reinforced polymer (CFRP) reinforcement technique for upgrading existing mine ventilation seals to withstand an explosion pressure of 50 psi or greater. The evaluation was conducted in the NIOSH Pittsburgh Research Laboratory’s Lake Lynn Experimental Mine (LLEM) near Fairchance, PA. The purpose of the evaluation was to determine the blast resistance of the CFRP reinforcement technique, designed to increase the strength of two types of existing 20-psi-rated in situ mine ventilation seals. Two candidate ventilation seals were selected to represent the 20-psi alternative seal designs typical of those used in mines prior to July 2006. Installed within the LLEM were (1) a 4-ft-thick pumpable cementitious foam seal using material with a designed 150- to 200-psi average compressive strength at 28 days and (2) a 24-in-thick, low-density cementitious block seal with a center pilaster and keyed to the floor and ribs. The materials necessary for the CFRP reinforcement technique were then installed on the outby (active) side of each seal, and the seals were subjected to explosion overpressures. Both seals with the CFRP reinforcement retrofit successfully withstood explosion pressures of 60 psi or greater during the full-scale evaluations in the LLEM.

Jan 1, 2008

By E. A. Rowe, G. H. Keith, B. D. Jones

An evaluation of electrowon tungsten powder was made by comparing its characteristics with conventional hydrogen - reduced tungsten powder . Electrowon tungsten powder was investigated with respect to particle size and shape , apparent density , flow rate , compressibility , green strength , and sintering characteristics . In addition , its chemical purity , absolute density , and purification by melting were determined . Significant findings were higher flow rates and better compressibility than hydrogen - reduced tungsten powder . However , the large particle size peculiar to the electrowinning process effectively prevented conventional sintering to a high- density material . The possibility of producing high - density material , using a new technique of hot swaging sheathed sintered - tungsten compacts , was demonstrated by the achievement of densities of 92 percent of theoretical .

Jan 1, 1965

By C. M. K. Boldt

The Bureau of Mines surveyed waste disposal sites at 18 metal and non-metal mines and conducted laboratory and full-scale field tests to de-termine the effects of tailings deposition techniques on physical properties of tailings pond beaches. Survey data included measurements of beach slopes, descriptions of deposition techniques, and measurements of beach physical properties taken at various distances from the point of discharge. Laboratory tests involved depositing two types of tailings, each with different grain-size distributions, into a settling trough and determining the resultant physical properties of settled materials along the length of the beach. Side confinement and the closeness of the water pool to the point of deposition caused the laboratory results to be inconclusive. Full-scale field deposition tests conducted at the tailings pond of a cooperating mine showed that there were similarities in relationships between exit velocities of tailings slurry and physical properties of the settled tailings on the beach.

Jan 1, 1988

By L. Hoogenboom

Under contract (H0232044) to the U.S. Bureau of Mines, Mechanical Technology Incorporated made an experimental investigation of the feasibility of measuring the load in roof bolts using a magnetostrictive sensor. The program was aimed at developing an inexpensive, moderately accurate, load-sensing element suitable for permanent installation and use underground. A combination of a cylindrical load-carrying sleeve under the bolt head and 3 removable circular multipole inductive sensor around the sleeve was tested. Program tasks included: design and fabrication of several sensors; design and manufacture of a large number of experimental sleeves; definition of electronic instrumentation specifications; design and manufacture of electronic sensor readout; and evaluation and testing of many sensor-sleeve combinations. Sleeves of different materials, various lengths, diameters and areas - with and without various nickel coatings -were combined with several experimental inductive sensors that were operated over a wide range of carrier frequencies.

Jan 1, 1974

By Keith L. Harris

Real gross national product3 (GNP) grew at a seasonally adjusted annual rate of 4.2% in the fourth quarter compared with a revised 4.3% rate in the third quarter, according to the most recent estimates released by the U.S. Department of Commerce (table 1). Expanding inventories, Government purchases of goods and services, residential fixed investment, and a narrowing of the trade deficit fueled the growth. Significantly reduced consumer demand led to the heavy inventory growth. Almost half of the buildup in inventories consisted of automobiles because consumers reduced purchases when Detroit ceased most incentive programs in late summer. Reduced consumer demand also affected imports, however, and the narrowing of the trade deficit resumed after widening in the third quarter. Nonresi- [ ] dential fixed investment also declined after a strong gain in the third quarter. On a year-to-year basis, the economy grew at an inflation-adjusted rate of 2.9%, the same as that of 1986. However, on a fourth-quarter-to-fourth-quarter basis, the real growth reached 3.8%, the highest growth since 19M, and exceeded the Reagan Administration's estimate of 3.4%. Rising merchandise exports accounted for about one-third of the growth in GNP for all of 1987 and are expected to continue to grow as domestic manufactures benefit from the lower value of the dollar vis-a-vis other major trading country currencies. Consumer demand became a less important factor of economic growth, but employment continued to grow (table 2), and civilian unemployment declined by 0.9 percentage points (December to December) as the industrial sector geared up to increase exports. Inflation, as measured by the fixed-weighted GNP price index, remained low at 3.4%.

Jan 1, 1988

By C. N. Rosenecker

The power required to circulate a gas-solids suspension was determined using a centrifugal compressor and a closed system. The suspension consisted of 18- to 40-micron glass beads in a mixture of 89 percent N2 and 11 percent CO2 at 20 psig. Solids-to-gas (S/G) ratios w re O to 2.2 lb/lb; gas flow rates were l.2 to 2.5 lb/min. Power requirement was found to follow the relationship hp t = hp(. + l), where hp t = the total power, and hpg = the power required for pure gas.

Jan 1, 1967

By E. G. King

Cerium and thorium sulfides have found use as crucible materials for melting certain radioactive metals. However, thermodynamic treatment of these sulfides has been hampered by lack of experimentally derived entropy values. This Bureau of Mines report describes heat-capacity measurements between 51° and 298° K, and entropy evaluations at 298.15° K, for cerium monosulfide (CeS), cerium sesquisulfide (Ce2S3), and thorium disulfide (THS2). The entropy values, with Literature results for the heats of formation, are used to obtain free energies of formation at 298.15°K. MATERIALS The samples used in this work were supplied by Prof, Leo Brewer of the Department of Chemistry, University of California. The methods of preparation and some of the physical and chemical properties of these sulfides were given by Eastman and coworkers.3 4/ Chemical analyses, conducted in our laboratory, gave the following results:

Jan 1, 1959