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By D. T. Peterson, T. Carnahan

The diffusion coejTicients of carbon, nitrogen, and oxyget were determined in $ thorium over the tempernilcre range 1440" io 1715°C. The diffusion coyfiicir?zls are given by: D = 0.022 exp (-27,000/RT) jor carbo)~, D = 0,0032 exp(-l7,00Q/RTj for nitrogen, and D = u.0013 expt(-11,UOU/RT) for oxygen. Cavl~orz was found to increase the hardness of thoriunz nearly linearly with concentration over the range 100 to 1000Ppm carbon. ThORIUM has a fcc structure up to 1365°C and a bcc structure from this temperature to its melting point at 1740°C. Diffusion of carbon, oxygen, and nitrogen in bcc thorium was of interest in connection with the purification of thorium by electrotransport.' In addition, it was possible to measure the diffusion of all three of these interstitial solutes in the same bcc metal. Only in niobium, tantalum, vanadium, and a iron have all three interstitial diffusion coefficients been measured in a given bcc metal. Diffusion coefficients have been measured for carbon and oxygen in a thorium by Peterson2, 3 and for nitrogen by Gerds and Mallett.4 Activation energies for diffusion are reported by the above authors to be 38 kcal per mole for carbon, 22.5 kcal per mole for nitrogen, and 49 kcal per mole for oxygen. Values of the diffusion coefficients of carbon and nitrogen in 3 thorium have been reported by Peterson et al.' However, these were secondary results of their investigation of electrotransport phenomena in thorium and it was hoped that the present study could provide more precise data. EXPERIMENTAL PROCEDURE The specimens used in this study were the well-known pair of semi-infinite bar type. The couple was formed by resistance butt welding two 0.54-cm-diam by 3.0-cm-long bars of thorium together under pure helium, the concentration of the solute being greater in one cylinder than that in the other. The finished couple then contained a concentration step at the weld interface and diffusion proceeded only along the axis of the rod. The thorium used in this study was prepared by the magnesium intermediate alloy method.5 The total impurity content was less than 400 ppm. The major impurities were: carbon, 100 ppm: nitrogen, 50 ppm; and oxygen. 85 ppm. The total metallic impurity content was less than 150 ppm. The high solute concentration portions of the diffusion couples were prepared by adding the solute to the high-purity thorium in a non-consumable electrode arc melting procedure. Carbon and nitrogen were added in the form of spectroscopic graphite and nitrogen gas while a Tho2 layer was dissolved by arc melting to add oxygen. High-purity thorium formed the low concentration portions in the carbon and nitrogen couples. The low oxygen portions were obtained by deoxidizing high-purity thorium with calcium for 3 weeks at 1000°C according to a method reported by Peterson.3 The high C-Th contained 400 ppm C, the high N-Th contained 400 ppm N, the high 0-Th contained 220 ppm 0, and the low 0-Th contained 25 ppm O. The high O-Th was brine-quenched from 1500°C to retain most of the oxygen in solution at room temperature. These concentration levels were all below the solubility limits in 0 thorium at 1400°C. A resistance-heated high-vacuum furnace was used to heat the couples. The samples were mounted horizontally on a tantalum support which had small grooves near each end. Spacer rods of thorium, 0.4 cm in diam, were placed in these grooves to prevent contact between the sample and the tantalum support. This arrangement should have prevented contamination of the sample by contact with the support. In further effort to reduce contamination, the oxygen diffusion couples were sealed inside evacuated outgassed tantalum cylinders lined with thorium foil. Thorium rings around each end of the samples acted as spacers in this case. Pressure during diffusion runs was about 10-6 torr after an initial outgassing stage. Temperature measurements were made by sighting on black body holes in the sample support adjacent to the samples with a Leeds and Northrup disappearing-filament optical pyrometer. Temperatures were constant during a diffusion anneal to ±5C. The observed temperatures were corrected for sight glass absorption after each diffusion run. The pyrometer was checked against a calibrated electronic optical pyrometer and a calibrated tungsten strip lamp with the electronic pyrometer being taken as the standard. All temperature readings agreed to within ±3C over the temperature range 1450" to 1690°C. Time corrections due to diffusion during heating and cooling were necessary because of the short diffusion times. The diffusion times ranged from 6 min for the oxygen sample run at 1690°C to 90 min for the carbon sample run at 1500°C. A series of temperature vs time plots were made for heating and cooling of the samples to the various diffusion temperatures. This data was then used in a method according to shewmon6 to determine the time corrections. The corrections amounted to

Jan 1, 1970

By John H. Fowler

"Most of the aggregate used in Nova Scotia is produced from numerous glaciofluvial and ice-contact deposits scattered throughout the province. Production from bedrock sources is increasing, with most of the coarse aggregate used in the Halifax-Dartmouth area coming from quarries operating within the metro area.A recently completed provincial sand and gravel inventory mapping program has identified some ""resource-poor"" areas where comprehensive aggregate evaluation programs are underway. Although some areas of the province are experiencing aggregate supply problems, large volumes are exported to markets as far away as Bermuda.IntroductionThe Nova Scotia Department of Mines and Energy has been involved with aggregate resource studies for several years, although sand, gravel and crushed stone are not designated as minerals under the Mineral Resources Act of Nova Scotia. Our role has been to provide the aggregate industry with resource data as well as provide similar information to governmental agencies involved with municipal planning, water resource studies and environmental protection regulations. Several private consulting firms use the information in many of their site development studies.We became involved with aggregates in a rather roundabout way. Several years ago, an outcry from inhabitants of a small coastal community over the removal of sand and gravel from a local beach moved the provincial Department of Lands and Forests to take action to protect provincial beaches. We were asked by the Department to provide information and to suggest alternative sources here operators extracting sand and gravel from beaches could relocate. This request initiated an aggregate inventory survey in southeastern Cape Breton, which was later extended to cover the entire province. The initial provincial sand z and gravel inventory survey provided a series of 1:50,000 maps showing the distribution of sand and gravel deposits in the province."

Jan 1, 1982

By Jose P. T. Agapito

Several underground coal mines currently operating in the Beckley District of West Virginia are experiencing serious roof and floor problems. A significant portion of the estimated two billion tons of coal resources may be lost as a result of these ground control problems. Preliminary studies by the Bureau of Mines indicated that these problems are due in part to a high horizontal stress field. During this contract study, a field program was conducted to quantify the horizontal in situ stress. A total of 14 overcoring sites (using the Bureau of Mines strain-relief overcoring technique) in five mines were drilled producing 53 data sets. Analysis of the data was done to provide in situ horizontal stresses for each of the five mine, and for the district as a whole. Stress data indicate horizontal stresses far in excess of that predicted by theory and in some cases, up to six times the estimated vertical stress. In addition to the field testing, a detailed computer modeling study was conducted using finite element and boundary integral (displacement discontinuity) methods. Verification of in situ stresses was obtained by the models and analysis of various development geometries, mining methods and remedial techniques were conducted. Recommendations for reducing ground control problems and future studies are presented.

Jan 1, 1980

Jan 1, 1988

By James M. Spear

The U.S. Bureau of Mines and the U.S. Geological Survey conducted a mineral survey of the Elk Creek RARE II area during the summer of 1981. The study area encompasses 18,900 acres [29.5 sq mi (7,680 ha)] along Elk Creek, 18 mi (30 km) southeast of Covello, California. No mineral resources were identified by the U.S. Bureau of Mines during this survey. Assay results of samples taken in this area indicate only trace amounts of manganese and chromium. No radioactive or fluorescent minerals were detected. No oil and gas, coal, or geothermal leases have been recorded for the study area.

Jan 1, 1982

By E. V. Kleber, V. F. Novy, R. C. Vickery

The constitutional diagram for the gadolinium-cobalt system has been determined. Seven intermetallic compounds have been found at compositions corresponding to the follwing gadolinium-cobalt ratios: 3:1, 1:1, 2:3, 1:2, 1:3, 1:4, 1:5. The GdCor compound has a congruent melting point above 1600°C. whereas the remaining compounds melt incongruently. Eutectics exist at 16 wt pct Co and 84 wt pct Co, with melting points of 620° and 1260°C, respectively. PREVIOUS papers'" have recorded constitutional data for systems of gadolinium with iron and nickel. This paper presents data obtained on alloys of gadolinium with the remaining 3d transition element-cobalt. voge13 found that cerium forms, with cobalt, the intermetallic compounds; Ce3Co, CeCo, CeCo2, CeCo3, CeCo4, and CeCo5 Other workers4-' found the 1:2 compound in this series to exist in a C-15 (face-centered cubic) structure and the 1:5 compound to exist in a hexagonal crystal system. Comparison of earlier data with that now reported will be made subsequently. EXPERIMENTAL Methods of alloy preparation, annealing procedures, and experimental techniques have been previously reported.' The cobalt content of alloy specimens was determined volumetrically. RESULTS Microstructure—The alloy containing 10.5 wt pct Co corresponds closely to the composition of the first intermetallic compound Gd3CO. In Fig. 1 the microstructure is essentially single phase composed of Gd3Co which formed peritectically. The globular areas are remnants of the peritectic reaction which did not quite go to completion. A eutectic occurs between Gd3Co and the next higher compound GdCO, which is followed by a series of peritectic compounds. Fig. 2, an arc-cast alloy containing 20.2 wt pct Co, shows large primary crystals of GdCo etching either white or black (depending on crystallographic orientation), embedded in the eutectic. Similarly, in Fig. 3 at 31.2 wt pct Co, a compound, probably GdCo3, has separated from the melt. Subsequent peritectic reactions were almost completely by-passed as the alloy cooled, the residual liquid freezing as a fine eutectic. In the 47.5 wt pct Co alloy, Fig. 4, the high melting point compound, GdCO4, has solidified as massive, white-etching grains, which reacted with the liquid to form GdCo3 as the second phase. The microstructure of an arc-melted alloy containing 60.5 pct Co is complex, Fig. 5, and presents some difficulty in interpretation. The grey etching matrix is probably primary GdCO4. The dappled phase represents grains of GdCO5 which have separated from the melt on cooling. The discrete spots in this phase are eutectic liquid. Small light etching crystallites are probably GdCO5 formed by the incomplete high-temperature peritectic reaction. GdCO4 is retained in arc-melted specimens containing 70.5 wt pct Co, Fig. 6. White areas of this compound are held in a matrix of GdCO5 the appearance of which is mottled slightly by inclusions of the second eutectic in this system. The development of the spheroidized eutectic at high cobalt contents is depicted in Fig. 7 (80.3 wt pct Co) in which the white massive crystals are GdCO5 compound. Further development of this eutectic is seen in Fig. 8, the primary white phase here being pure cobalt. Thermal Studies—Differential thermal analyses and melting point determinations have yielded the data shown in Fig. 10. The high gadolinium eutectic, indicated by microscopy, was confirmed at about 16 wt pct Co, melting at 620°C . A eutectic also occurs at about 84 wt pct Co melting at about 1260°C. The thermal arrests at 8803 960°, 1060; and 1210°C,

Jan 1, 1962

The Dizon open pit mine of Benguet Corporation in western Central Luzon, Philippines has yielded some 182 000 t copper, and about 26 000 kg gold and 48 000 kg silver as by products since it started operation in November 1979. The 140 million tonne orebody is associated with a small quartz diorite porphyry stock emplaced in volcanic rocks on the basal slope of a stratovolcano complex as stockworks, fracture fillings and disseminated sulphide mineralization averaging 0.43% Cu, 0.93 g/t Au and 2.5 g/t Ag. Intense hydrothermal alteration accompanied the mineralization that developed fairly distinct mineral assemblages within and around the intrusive. Post-ore volcanic activity later gave birth to an upward-flaring diatreme which broke out south of and adjacent to the orebody and partially destroying it. Subsequent volcanic activity buried the mineralized area along with the rest of the stratovolcano's surrounding slopes under a thick deposit of pyroclastic and laharic debris. Erosion eventually removed the volcanic cappings over Dizon and also exposed the quartz diorite porphyry stock which might have resulted in the truncation of a sizeable section of the Dizon deposit. The chain of stratovolcanoes that comprise southeastern Zambales range hugging the southeastern edge of the Zambales ophiolite is part of a west-facing volcanic arc that extends for some 300 km along the western margin of central and southern Luzon whose development has been correlated to the subduction in the Manila Trench located off the west coast of Luzon. Prominent WNW-trending lineaments that cut across the ophiolite appear to be splays of the Philippine Fault whose intersection with the Mt. Pinatubo stratovolcano complex might have localized the emplacement of a number of intermediate stocks along with the gold-rich porphyry copper mineralizations associated with some of them.

Jan 1, 1987

By Stanley Griff, William Herrera, William O. Seals

"The Navy initiated liquid propellant research in the early 1940's. The first promising Navy liquid propellant, Otto Fuel II, was developd in the early 1950 as a potential torpedo fuel. Later, the Navy developed a HAN based liquid propellant designated NOS-365, a hydroxylammonium nitrate, isopropylammonium nitrate and water formulation. A large gas volume generated by this propellant produced a large wake behind the torpedo. As one can readily understand, this negated the useof the propellant for this application. Recognizing the large gas volume as a desirable propulsion system for guns, the Navy embarked upon a gun propellant proqam. Utilizing a bulk loaded gun sysytem, the program failed when the gun was destroyed by the propellant detonating."

Jan 1, 1990

By Rodney G. Orr, Phil Robertshaw, Roland Loewer, Klau Lehnert-Thiel

This paper documents the 1988 discovery and subsequent evaluation (to 1991) of diamond bearing kimberlites in the Fort à la Corne area, Saskatchewan, by Uranerz Exploration and Mining Limited. Cameco Corporation began participating as a joint venture partner (50%) in mid-1989. The first indications that kimberlite-type intrusions might exist in the area carne from Geological Survey of Canada aeromagnetic maps. Because of the overburden thickness (over 100 m), magnetometer surveys continue to be the main exploration tool in defining pipe locations and sizes. Magnetometer surveys in varying levels of detail have outlined one main cluster and two sub-clusters, the main group being some 10 km by 50 km in size. In excess of 70 individual targets have been interpreted from the magnetics as probably representing kimberlites. The size range of the individual magnetically-defined bodies is between 1 ha and 74 ha. Proof that the magnetic anomalies were kimberlite intrusions carne in 1989 when each of seven test holes, all drilled on different targets, intersected the potential diamond host rock. The majority of the targets tested were diamond-bearing, with the indicator mineral chemistries suggesting that both peridotitic and ecIogitic diamond parageneses could be expected. To date, 18 individual kimberlite bodies have been drill-tested. A total of 39 bulk samples, amounting to 186 t (representing 360 t of theoretical sample recoveries) were processed in 1990 and 1991. One hundred and sixty diamonds were recovered, averaging 0.04 carats in weight, the largest being 0.6 carats. Most of the bulk sample grades are less than 2 carats/loo t; only three bulk samples have higher grades, the best being approximately 10.5 carats/l00 1. The diamonds are predominantly gem-quality stones.

Jan 1, 1992

By E. A. Mihok

A pilot plant for treating mine drainage by neutralization with limestone was designed, fabricated, and operated by the Bureau of Mines. The process consists of (1) producing a very fine (minus 400-mesh) limestone slurry, (2) mixing the slurry with the mine water, (3) aerating the resulting mixture to remove carbon dioxide and precipitate iron, and (4) separating the solids from the liquid by sedimentation. A mine discharge of pH 2.8, containing 1,700 ppm total acidity, 36 ppm ferrous iron, and 360 ppm total iron, was treated at rates from 300 to 400 gpm. The treated water ultimately reached a pH of 7.4 and contained no detectable iron. The resulting sludge compacted to approximately one-third the volume of sludge from mine water neutralized with lime. The advantages of the limestone process, compared with the conventional lime process are as follows: Widespread distribution and lower cost of run-of-mine, indigenous limestone; simplicity of plant design; reduced hazards and plant operating and maintenance costs accruing from the use of a less reactive chemical agent; higher solids concentration of the precipitated sludge; and no deleterious effect caused by accidental overtreatment. While total process costs could not be determined, it is conservatively estimated that the cost of treating mine water by the limestone process is one-third to one-half the cost of the lime process, depending on the characteristics of the water to be treated and the availability and quality of limestone used.

Jan 1, 1968

By S. G. Cupschalk, F. A. Dahlman, J. J. Wert

Studies have been undertaken to determine the indicidual effects of particle size, degree of long-range ovder, antiphase domain size, and root mean square stran on the microhardness and yield strength of ordered alloys. Dnta have been analyzed for Cu3Pt initzally ordered to a value of 0.82 and after deformations of 1 and 6 pct. It was observed that deformation fleatly reduced the degree of long-range order. Furtherrnore, wztkin this range of relatively small deforntntlons, the average particle size changed very little while the antiphase domain size was greatly reduced. Smultaneosly, the mcrohardness changed by a factor of two durzng the deforrtation process. PREVIOUS studies have reported some of the effects of cold work on the broadening of X-ray diffraction peaks. These investigations were performed on powder and wire samples representing both ordered and disordered states; i.e., the specimens were initially studied in a severly cold-worked condition. By comparing the difference in line shape between the annealed and cold-worked peaks, fundamental information was obtained concerning particle size, strain distribution in different crystallographic directions, degree of long-range order, and change in antiphase domain size. Considerable theoretical work has been done concerning the analysis of diffraction data obtained from cold-worked metals. Stokes' expressed the change in diffraction profiles in terms of Fourier coefficients. Much of the work in this area has been summarized by warren2 in an extensive review article concerning the analysis of plastic deformation by X-ray diffraction. Cohen and Bever3 applied these techniques in studying the effects of cold work on alloy systems exhibiting long-range order. They utilized the Fourier coefficients of fundamental peaks in conjunction with those of the superlattice peaks to determine the change in antiphase domain size. Little work of this nature has been reported for ordered systems that have undergone small degrees of plastic deformation. The purpose of this investiga-tion was to determine the effects of small deformations in such a material with respect to particle size, strain distribution in various crystallographic directions, antiphase domain size, degree of long-range order, and hardness. EXPERIMENTAL PROCEDURE CusPt was used for the initial investigation since the order-disorder transformation takes place with- out a change in crystal structure. The transformation is readily detectable via X-ray diffraction techniques due to the large difference in the scattering factors of copper and platinum. Additionally, the alloy is relatively low melting (approximately 1300°C) and is easily deformable in both the ordered and disordered states. 1) Specimen Preparation and Cold Working. A 100-g, 12-in. diam., cylindrical specimen of Cu3Pt was prepared by melting and casting 99.99 pct pure Cu and Pt i.n vacuo. Prior to any mechanical working, the material was homogenized in a vacuum for 60 hr at 100O0C, and surface defects were removed by machining to a depth of approximately 116 of an in. The material was then cold-rolled, with an intermediate anneal, into a strip approximately 12 in. wide by 14 in. thick. Straightening and flattening removed another 0.025 in. from the thickness. After a recrystallization treatment at 750°C for 30 min, the specimen was slow-cooled from 55OoC, at the rate of 6°C per hr, down to 150°C to induce superlattice formation. This treatment yielded an ASTM grain size of 7 and a degree of long-range order equal to 0.83 0.06. After obtaining X-ray and Knoop hardness data, the sample was cold-rolled approximately 0.75 pct in one pass through a hand-operated jewelers' mill. X-ray and hardness data were again obtained and the specimen was reduced an additional 5.41 pct in a single pass through the mill. 2) X-Ray Measurements. The specimen was examined in the ordered condition and after the two degrees of cold working previously mentioned using a General Electric XRD-5 unit equipped with a spectrometer and scintillation counter. Using Mo-Ka radiation with a zirconium filter, six orders of the 100 reflection were obtained. It was anticipated that point counting would be necessary for an accurate determination of the low-intensity peaks and tails: however, it was demonstrated that, by using a scanning speed of 0.2 deg per min and the appropriate time constant, the recorded data were sufficiently accurate. Thus, for ease of experimental procedure, all peaks were recorded on chart paper. Specimen position in the holder was considered to be insignificant after making a series of measurements of the same peak area in different positions with respect to the beam. Since peak overlapping did occur at high values of 20, it was necessary to separate the peaks graphically prior to analyzing the data in order to minimize this source of error. The peak tails were also carefully drawn to obtain the best possible data. Fourier coefficients of the line profiles were calculated on an IBM 7072 computer, and graphical meth-ods2j3 were employed in analyzing the results. For this type of calculation, in which the line profile is represented by intensities taken at set intervals, the intervals selected must be sufficiently small to give an accurate representation of the line profile. It was decided that for 20 = 0.02 deg the line profiles were

Jan 1, 1967

By R. F. Rolsten

The preparation of pure metals by the thermal decomposition of volatile halides was developed byde boer' and van Arkel.2 This has proved to be a useful technique for the refining of columbium,the mechanical and physical properties of which are seriously altered by such interstitial contaminants as oxygen, nitrogen, hydrogen, and carbon. The conventional deposition surface of a resis-tively heated metal filament was replaced, Fig. I, with an indirectly heated clear quartz surface. The impure columbium (feed) was contained in the annular space between the Vycor deposition bulb and the perforated molybdenum retaining cylinder. The head assembly was attached to the deposition bulb by fusing the Vycor at "A". This unit was then connected to a vacuum system composed of a three-turn glass coil to eliminate fracture due to vibration or expansion, a McLeod gage, a cold trap, a two-stage mercury diffusion pump, and a mechanical pump. The entire system was cold outgassed, and the 10 to 20 g of iodine in the auxiliary bulb (reservoir) was held in dry ice to prevent excessive loss of iodine. The columbium was hot outgassed at 800" to 825oC with the pressure maintained at l0-5 to 10-6 mm Hg for 48 hr and cooled under vacuum to 200° to 240oC. Iodine was sublimed from the reservoir and collected in the deposition bulb. The feed material temperature was adjusted to give the desired iodide vapor pressure and the finger temperature of 1000" C was independently attained and measured with a platinum-platinum 10 pct Rh thermocouple located in the center of the nichrome wire helical heating element, "F." The system was attended until temperature equilibrium was established, whence it operated without attention. This is a definite ad- vantage over the conventional "hot-wire" technique which required either constant attention or automatic control. In operation, the iodine vapor originally introduced into the vessel reacted with the crude metal to form a columbium iodide. This iodide vapor diffused to the hot deposition surface where it thermally decomposed, depositing columbium and releasing iodine. This liberated iodine then diffused back to the crude columbium where iodide was formed again. Thus, by repetition of this process, the iodine carried pure columbium from the crude material to the filament, where it deposited. The success of the "iodide" process in producing ductile metals depends on preventing the transfer of oxygen, nitrogen, hydrogen, and carbon from the feed material to the deposit. In many cases relatively minor quantities of these interstitial contaminants impair the ductility of metals. The material produced by the iodide process has such exceptional ductility that it is frequently and mistakenly assumed that iodide metal is always of very high purity. This assumption is not necessarily true since a number of metallic impurities can also be transferred. In the present investigation, the temperature of the feed material was adjusted to iodinate selectively and the deposition temperature adjusted to decompose the iodides selectively. By this technique, some metals present in the feed material were prevented from codepositing with the columbium. It is quite important to have the feed material symmetrically located around the deposition surface in order to obtain a uniform deposit at the maximum rate. For example, Runnalls and pidgeon3 observed that, when the base of a titanium filament was about 1 cm from the feed material, deposition was rapid on that section close to the feed, but that the rate decreased with distance from the feed so that a

Jan 1, 1960

By Khamis Y. Haramy

This Bureau of Mines paper describes the use of the borehole shear tester (BST) In mines. Assembly and procedure sections explain how the equipment is assembled and used properly. Schematics of the BST, limitations, test hole specifications, data recording and calculations are all explained briefly, and an example of the data collecting and calculations is given to assist understanding.

Jan 1, 1981

This report summarizes the results of several field tests conducted by Collins for the Bureau of Mines under contract S0122076 and contract H0232056. The field projects represent a part of Collins continuing effort on a broad study of coal mine communications. These experiments analyze the propagation characteristics of radio signals in a working coal mine environment. The intent of the program is to provide basic propagation loss characteristics by which we may evaluate various approaches to an integrated mine communications system. The goal of such a system is to satisfy both operational and emergency communications needs in the mine.

Jan 1, 1974

By Edward Hyde

THE HIGH-TEMPERATURE SCALE IN OPTICAL PYROMETRY AT the basis of optical pyrometry lie the theoretical and experimental data of the so-called blackbody. The black body is essentially a theoretical conception, with certain simple properties attributed to it -fundamentally, the property that its radiation at any temperature is a unique function of the temperature and does not involve any other variables. As a theoretical conception, an equation has been developed by Boltzmann connecting the total radiant power with the temperature, and another equation by Planck connecting the distribution of radiant power throughout the spectrum with the temperature. The integral of the latter with respect to wave-length conduces to the former and permits the evaluation of the constant c1 of the Planck equation, ass given in the form. J-= cl?-5 c2 (1) e ? T ? 1 assuming that the constant Q of the Stefan-Boltzmann law E=a(T4-T40) is known. The other constant c2 is arrived at by other methods, which will be discussed later. This equation for the black body lies at the foundation of optical pyrometry. To make the discussion complete, it should be stated that the theoretical black body is quite closely realized by a hollow enclosure with walls at a uniform temperature and radiating through a small orifice. The electrically heated black body, first introduced by Lummer and Kurlbaum, is an essential part of the equipment of a pyrometric research or testing laboratory. Numerous investigations have shown that its radiation conforms to that of the theoretical black body within experimental errors. Hence by operating the electrically heated black body at the melting point of some pure metal for which the temperature of melting has been determined on the vas scale. a standard is obtained for comparison with

Jan 9, 1919

By G. St. J. Perrott, G. W. Jones

"In the course of its investigations pertaining to the promotion of safety the Bureau of Mines is actively engaged in investigating all promising materials that may be of value in rendering methane or other combustible gases, vapors, or solids less inflammable.Added substances are of value if such additions narrow the limits of inflammability, raise the ignition temperature, lower the speed of propagation of flame, or reduce the maximum pressure developed. Of major importance is the effect of added materials on the limits of inflammability, because methane is the chief combustible s liberated in mines, considerable work has been done with extinguishing agents on methane flames. For obvious reasons, a substance to be of value for the extinction flames should be a gas, or a liquid having a sufficient vapor pressure to give concentrations of the vapor in sufficient amounts to extinguish the flames or markedly narrow the limits of inflammability. The substance should be nontoxic, cheap, and noncorrosive and must be incombustible. Solids, such as rock dust, are undesirable and of little value for combustible gases because they soon settle out of the atmosphere, and their flame- extinguishing value is thereby lost. There are at present only a few gases and vapors-for example, nitrogen, carbon dioxide, and carbon tetrachloride-which meet these requirements.The extinction of methane flames by nitrogen, carbon dioxide, and argon has been reported by Coward and Hartwell 4; the extinction by water vapor by Coward and Gleadell 5, and the extinction by helium and carbon tetrachloride by Coward and Jones 6."

Oct 1, 1930

By Bruce Rock

A continuous mining machine was redesigned for the installation of an integrated illumination system. The illumination system was designed by first calculating the theoretical number of luminaires required to meet the Federal Illumination Standards. Luminaires initially were placed using isointensity diagrams. A darkroom was used for "fine tuning" and demonstrating that the system met the illumination requirements. The luminaire mounts were installed on a machine underground. The performance of this illumination system was monitored in the working environment of an operating coal mine. Design changes were made as necessary during this evaluation period to improve the system.

Jan 1, 1979

By N. E. Garner

Laboratory experiments were conducted to investigate the cutting of a single diamond on limestone and shale under simulated down-hole conditions. A high-pressure chamber was modified by adding a rock-rotating device so that planing tests could be run. Weight on the diamond, diamond geometry and differential pressure across the face of the rock were varied. It was found that (I) high differential pressure reduced the volume of rock cut by the diamond at a given bit weight by strengthening the rock and changing the mode of failure; (2) a finely powdered rock left in the bottom of the grooves reduced the volume cut by as much as 50 percent; and (3) orientation of a single diamond about the axis of a drill point had considerable influence on diamond cutting efficiency. INTRODUCTION Diamond bits consist of many diamonds held in a matrix provided with water courses for fluid passage to clean, cool and lubricate the diamonds as they drill formation. Each diamond contributes its share to the overall effectiveness of a bit, but a lack of understanding of the performance of a single diamond has hampered efforts to engineer improvements in diamond bits. The need for those improvements prompted this study. This paper describes the findings of a laboratory investigation of the outting action of a single diamond where the differential pressure between the wdlbore and formation, diamond geometry and vertical force on the diamond were independently varied. The tests were conducted in a pressure chamber that provided relative horizontal motion (planing) between a rock and diamond under simulated down-hole pressure conditions. EQUIPMENT HIGH-PRESSURE CHAMBER WITH ROTATING DEVICE The high-pressure chamber used in previous rock mechanics studies' was modified for this study by addition of a rock-rotating device. The modified chamber (Fig. 1) differs from the old chamber in that the rock can be rotated to provide relative horizontal movement between the rock and the penetrator which may be a small element of a diamond or a drag bit. In this study the penetrator was a single diamond. The rock sample holder inside the chamber is mounted on a thrust bearing and is connected to the external drive mechanism by a stem that passes through two seal elements. The seal elements are needed to allow formation pressure to enter the bottom of the rock sample through a small hole in the stem. The Kapseal seal elements (Tefion boots backed by O-rings) provide low friction (hand free) even at differentials of 5,000 psi. The drive mechanism is a variable-speed transmission with a speed range from 0 to 30 rpm and an output torque of 2,800 in.-lb. A right-angle-drive gear box couples the drive to the stem. The new design has two independent pressure systems (formation and borehole) to simulate down-hole rock stress environment. Formation pressure enters from the bottom of the rock through a 6-in. diameter area, and borehole pressure acts over the remaining surface. A 14-in. layer of zero fluid loss oil-base mud poured over the top of the rock and an O-ring seal on bottom allow a differential between the borehole and formation pressures. Bayol 50 was used as the hydraulic fluid in the chamber. The differentials reported here were obtained by elevating the borehole pressure while keeping the formation pressure at zero.

By F. W. Jessen, C. C. Patton

Adsorbed films were formed on polished stainless steel specimens from dilute benzene solutions of two crude oil distillation residua. Although the two residua were extremely dissimilar in composition, contact angle measurements showed that the two films increased the wettability of the steel specimens to oil by equal amounts. Furthermore, the wettability of the films was essentially unaffected by the desorption techniques used. Paraffin deposits were formed from heptane-wax solutions on the same stainless steel specimens. These deposits definitely adhered to the surface. Presence of an adsorbed crude oil film on the metal surface increased its free surface energy and resulted in increased deposition of paraffin. The addition to the heptane - wax solution of small amounts of the same distillation residua that were used to form the adsorbed films resulted in decreased cohesive strength in the deposits formed, which resulted in decreased deposition. The presence of a crude oil fraction both in the solution and as a preadsorbed film eliminated the adherence of a deposit of any kind. A mechanism of deposition is proposed which explains the results obtained. INTRODUCTION The natural formation of any predominantly organic accumulation in oilwell tubing, surface flow lines or other production and storage facilities is called a paraffin deposit. These deposits restrict the production of crude oil, causing a substantial increase in production costs because of decreased flow capacity, expense for periodic deposit removal and unproductive downtime. The conditions under which such deposits form, their physical characteristics and the nature and severity of the problem created are extremely varied. Over the past several years, much progress has been made in developing and utilizing methods to remove accumulated paraffin deposition. However, like so many other problems, the basic stumbling block appears to be a lack of understanding of the fundamental mechanism involved in the formation of such deposits. Crude petroleum is known to contain considerable quantities of polar, surface active substances which Doddl has shown to be present at the oil-water interface. Denekas, Mattax and Davis2 observed that the wettability of reservoir rocks was drastically altered by exposure to crude oil fractions; and Zisman, et a1.3 showed that the nature of the compounds adsorbed on a surface would determine its wettability characteristics. Cole and Jessen4 and Ehrig5showed that surface wettability can have a profound effect on the magnitude of paraffin deposition, and Parks6 demonstrated chat the presence of certain adsorbed films on a metal surface would reduce the adherence of paraffin to that surface. Zisman7 has since advanced the theory that the conditions for adhesion are the same as for wetting. Therefore, it was felt that there was adequate evidence to support the supposition that adsorption of compounds from a crude oil might play an important part in paraffin deposition. ADSORPTION-WETTABILITY EXPERIMENTS Initial experiments were conducted to determine the effects of adsorption from solution of crude oil residua on the wettability of a polished stainless steel surface. Distillation residua with initial atmospheric boiling points of 700F were used in preference to the whole crudes in order to concentrate on the molecular weight range of interest, and to eliminate the possibility of composition change due to evaporation of the light ends. Also, these high boiling materials would be expected to be adsorbed from the whole oil in preference to similar compounds of lower molecular weight.

Jan 1, 1966

This report presents the results of reconnaissance-level investigations of the mill refuse disposal systems for 15 plants throw-heat the conterminous United States. The sites visited represent a cress section f the copper, iron, lead and zinc, and phosphate industries' practices in the field of fine-grained refuse disposal. The reconnaissance-level investigations were carried out to gather supplemental data to tae in-depth studies of Kennecott's Magma and Phelps Dodge's Morenci tailings deposits and Kennecott's Chino leaching dump. The various sites visited were classified according to the different systems and techniques used by the mining industry. The probable effects and relationships between site conditions and disposal methods were determined and evaluated to the extent feasible by a reconnaissance level investigation.

Jan 1, 1974