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By R. Simon

Maurer's review1 summarizes quite thoroughly the various theoretical developments and experimental findings that contribute to the knowledge of rock mechanics in drilling. This discussion supplements Maurer's paper by including generalities that either have been incompletely treated in his review, or formulated from new considerations by the discussant and from hitherto unpublished experimental data. These generalities are associated with the observation that all mechanical methods of rock drilling essentially comprise a sequence of indexed, concentrated loadings on the bottom of the hole being drilled. A concentrated loading is defined as a mechanical loading by a tool that contacts at any one time only a small fraction of the surface of the body being worked and penetrates only a small fraction of the body thickness. The surface in this application is the bottom of the hole. The deformation of ductile material by concentrated loading has received considerable attention because of the importance of indentation tests for measuring hardness of metals. Some of the generalities involved in concentrated loadings on ductile materials apply also to concentrated loadings on more brittle materials such as rock. Among these generalities is the applicability of similitude considerations to scaling laws and to force-displacement and energy-volume characteristics for tools of various shapes, as summarized by Tabor.2 Vork on the flow and fracture behaviors of glass loaded with pyramidal and spherical indenters is reviewed by Douglas.3 Maurer refers to the work of Evans and Murrell on wedge loadings on coal and on mixtures of pitch and sand. It is evident from Maurer's paper that a considerable portion of the studies of rock mechanics in drilling, such as crater formation experiments, has involved concentrated loadings on rock.

Jan 1, 1967

Wrenching between basement blocks is considered to be the mechanism whereby a well developed set of en echelon folds and an associated fracture system are developed in the Fitzroy Depression, Western Australia. The regular geometry of these structures accords with a right lateral regional coupling between high-standing, basement blocks bounding a trough filled with a thick pile of stratified Phanerozoic sediments. The structures developed during or after the Mesozoic Era, but the couple is inferred to have been applied to blocks outlined by old lineaments, which may reflect strains or ruptures in basement that developed during the Precambrian, and which were regenerated during Palaeozoic and Mesozoic time.

Jan 1, 1967

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 Charles R. Simcoe

It was pointed out in a recent paper'g that the initial flow stress of as-quenched martensite is very low even in an alloy steel with an M, well above room temperature. It was also shown that the high ultimate tensile strength resulted from a very high rate of work

Jan 1, 1967

By E. L. Day

"In the early 1930s during the course of test work with a simple gold ore, it was evident that the time required to dissolve the gold by cyanidation was very much longer than should have been needed theoretically for the maximum size gold particles in the ore, A similar conclusion appeared to be valid for other gold ores. In a cyanidation system there are many factors which can influence the dissolution rate of gold, and a decision was made to investigate the more obvious variables, because a literature survey at the time showed that with the exception of the work of Yamazarki on the dissolution of silver in cyanide solution, virtually no attention had been given to this subject, Our work was not reported because the intention was to do this on completion of the Study, but owing to the demands on the Section's personnel for other work the investigation was never completed. Although other investigators have since studied the problem, the methods which we adopted and some of the conclusions may be of interest to metallurgists concerned with gold ore treatment.Form of GoldExperiments with gold ores were not possible because of the number of uncontrollable variables present in a gold ore-cyanidation system, therefore pure metal and reagents were used. Initially some experiments were carried out with gold leaf, but it was soon apparent that metal in this form was unsuitable because the uneven thickness of the leaf caused it to break up into pieces and. there was difficulty in determining precisely when complete dissolution had taken place, Numerous factors both expected and unexpected were found to influence considerably the results and much experimental work was necessary to establish the procedures which were finally adopted, Experiments were carried out with gold in the form of foil, wire, rings and sols. Finally, gold foil in the form of cylinders was adopted for most of the experiments although some work with gold in the sol form was included in the programme. Also some experin1ents were carried out with a gold ore to see if effects which were obtained with sodium chloride on gold sols were applicable to gold ores."

Jan 1, 1967

By George W. Healy, Ko Yamaguchi

In typical calorimetry the energy given off by a material under study is transferred to a water bath, whose temperature is sensed by a thermometer; for correct measurement the water bath must attain a uniform temperature to which the thermometer must respond. This introduces two sources of error, non-uniformity of the heat sink and a time lag until its temperature is registered. These errors may become important where a rapid process such as solidification of metals and alloys is being studied by means of Oelsen'sl quantitative thermal analysis. To overcome this difficulty, a calorimeter sink was conceived in which the water bath is replaced by a copper coil, which serves simultaneously as heat

Jan 1, 1967

By P. L. Hendricks, J. W. Spretnak

The interstitial atom principally responsible for the yield point and strain aging in electron-beam-melted tantalum is identified by analysis of the kinetics of the return of the yield point after an increment of plastic deformation. Two sets of specimens contained two levels of oxygen with very low hydrogen contents and the third set had comparable oxygen and hydrogen contents. The activation energy for the return of the yield point agrees well with that for diffusion of oxygen for the first two sets of specimens. For the third set of specimens, the activation-energy value lies between those for diffusion of hydrogen and for diffusion of oxygen. The advent of the dislocation model of plastic deformation in metals has revitalized interest in the yield point and strain aging in bcc metals containing a certain minimum content of interstitial solute elements. Much theoretical and experimental work has been performed in recent years to elucidate the detailed mechanism of these phenomena. The purpose of this investigation is to attempt to identify the principal interstitial element responsible for the yield-point phenomenon in electron-beam-melted tantalum by analysis of the kinetics of the return of the yield point after an increment of plastic deformation. Some of the earlier theories of the yield-point phenomenon proposed a grain boundary film of iron carbide. Such models could not satisfactorily explain all features of strain aging and the yield-point phenomena. The most widely accepted explanation is that of Cottrell,1 later extended by Cottrell and Bilby.2 Strain aging is ascribed to "locking" of dislocations by interstitial solute "atmospheres". The yield-point phenomenon results when the dislocations are torn away from their atmospheres. The strain-aged condition is re-established after sufficient time to allow the interstitial atoms to diffuse to the dislocation lines and re-establish the locking atmospheres. Clearly, the Cottrell-Bilby model is concerned with the bulk of the grain and does not specifically involve the grain boundary. The recent modification of the Cottrell-Bilby model is a redirection of attention to the role of the grain boundary and the possibility of multiplication of a limited number of free dislocations rather than unlocking all of the dislocations. Theories have been advanced by Hahn3 and conrad4 which are modifications of the Cottrell-Bilby theory. The model proposed by Hahn indicates that, although the possibility of un- locking anchored dislocations is not excluded, it implies that unlocking is not necessarily required to explain yield drop. Locking of dislocations during the aging treatment is a necessary part of the theory; however, it assumes that dislocations once locked remain locked. It is suggested that the yield drop observed is a result of the following factors: 1) the presence of a small number of mobile dislocations initially, 2) rapid dislocation multiplication, 3) the stress dependence of dislocation velocity. In the case of bcc metals, locking is considered to be the means by which dislocations are immobilized. Cold working of the metal results in the generation of larger numbers of new dislocations and the stress dependence of the dislocation velocity accounts for yield drop observed. Conrad' has proposed a model similar to the one just described which applies to strain aging of iron and steel and which logically could be extended to other bcc metals. This model also does not require large-scale unlocking of dislocations. It is proposed that, during initial loading of a specimen below the upper yield stress, a few dislocations are torn free of their Cottrell atmospheres at regions of stress concentrations. With an increasing stress, some multiplication of dislocations occurs by a double cross slip mechanism, thus giving a preyield microstrain. At some critical stress represented by the upper yield stress, sudden profuse multiplication of dislocations occurs, enabling plastic flow to proceed at a lower stress. In this model, microstrain, preyielding, and flow represent the movement of free dislocations. It should be noted that this model also requires the locking of dislocations by interstitial solute atoms for the occurrence of a yield point; however, unlocking of large numbers of dislocations is not required. If it is assumed that the yield point will return when some fraction of free dislocations produced during pre-straining are pinned, the number of solute atoms required to pin unit length of a dislocation line can be calculated when prestrain and reloading are done at the same temperature and strain rate. Since the migration of solute atoms back to the stress fields of dislocation lines is controlled by the diffusion rate of interstitial solute atoms, it is to be expected that the activation energy for strain aging would be identical to the activation energy for diffusion. It would also be expected that the strain aging observed will be controlled by the fastest diffusing species capable of producing locking over the temperature range investigated. The rate of yield-point return has been found to be adequately expressed by an empirical rate equation of the form: rate=Ae-Q/RT [1] where A = constant, Q = activation energy, R = gas constant, and T = absolute temperature. Cottrell and Bilby2 have expressed the number of atoms per unit length of dislocation line which arrive

Jan 1, 1967

By K. L. Komarek, P. F. J. Landler

Synthetic polycrystals of wustite were reduced ilz H2-H2O mixtures over limited roncentration ranges wiltun the wustite. field and the weight changes were continuously followed with a McBain quartz spiral balance. The reduction was. found to be controlled by a combined surface plus solid-state diffusion reaction. The solid-state diffusion had an activation energy of 38 kcal. Self--diflusioities of iron decreased with itzcreasing vacancy concentration. The activation energy of. the surface reaction runs different tor- different samples. The surface reaction-rate constan increased with increasirzg vacancy concentration. THE reduction of the oxides of iron has been studied for many years. Edstroem' has summarized the early work and has provided much information on the reduction of magnetite and hematite by hydrogen and carbon monoxide. More recent summaries are those by smeltzer2 and Themelis and Gauvin.3 Most investigators have reported that the iron metal which forms the outer layer during gaseous reduction is rather porous. According to Kohl and Engel14 the formation of such a porous iron layer depends on the properties of the underlying wiistite layer, on the reaction of the gas with the wustite surface, and on the transport of matter through the wustite layer. McKewan, Quets, Wadsworth, and Lewis, and Knacke 10 have found that, if a porous iron layer is formed, a surface reaction between gas and wustite at the bottom of the pores controls the rate of reaction. Seth and ROSS 11 and Warner 12 have pointed out that the influence of the gaseous pore diffusion through the porous iron layer cannot be neglected. It has further been shown that the wiistite layer formed during reduction is dense and that transport of matter across the layer occurs only by solid-state diffusion of iron ions.13,14 The solid-state diffusion rates observed by Edstroem and Bitsianis 14 and the surface reaction rates observed by Quets eta1.' show that an interaction of the two steps in controlling the reaction rate has to be considered. In this investigation the reduction of wustite was studied with respect to the interaction of the two steps, isolated from any other effects, by reducing wustite within the wustite field from higher to lower oxygen concentrations with H2-H2O gas mixtures. A similar study with CO-CO2 mixtures has been performed by Levin and wagner.15 Fused synthetic wustite polycrystals were reduced in steps of 0.4 wt pct from 24.4 to 23.2 wt pct 0 and over a temperature range from 700" to 1050°C. A few tests were also conducted with reduction steps from 24.4 to 23.6 wt pct 0 and 24.5 to 23.2 wtpct0. The Fe-O phase diagram is shown in Fig. 1 where the composition of the gas phase in equilibrium with the condensed phases is plotted as pct H2 vs the temperature. A careful study of the literature led to the conclusion that the fully drawn equicomposition curves (in wt pct O) in the wustite field used by Edstroem 1,16 and other authors needed some correction. Based on results by Darken and Gurry17 (shown as open circles) and on some of our own data, four corrected curves for 23.2, 23.6, 24.0, and 24.4 wt pct O were calculated (drawn as dashed lines in Fig. 1) which should replace the fully drawn equicomposition curves. MATERIALS AND APPARATUS Materials and Specimen Preparation. Wustite was prepared from iron sulfate (Fisher Scientific Co., New York) which had a purity of over 99.92 pct, with small amounts of manganese, copper, and zinc adding up to 0.03 pct. From the aqueous solution iron oxalate was precipitated and decomposed to magnetite according to Economos. 18 The magnetite powder was pressed into cylinders and sintered in vacuum at 900°C for several hours. The sintered compacts were placed in a platinum crucible of 2.5 cm diam which was fitted into a high-purity alumina crucible and then inserted into the center of the graphite heating element of an electric resistance furnace.lg The furnace was evacuated to below 1 p Hg and the magnetite sample was slowly heated. The evolution of gases during heating deter-

Jan 1, 1967

By Thornton L. Neathery

Geologic investigation of a mineralized zone in eastern Alabama indicates that large quantities of talc and soapstone are scattered over a wide area close to the surface. Laboratory experiments show that this material may be upgraded to a high-quality talc. A market survey indicates that the talc deposits may be of current and long-range interest. The anthophyllite asbestos which is associated with the talc does not appear to occur in sufficient quantities to be considered as a primary commercial source.

Jan 1, 1967

By Edwin M. Thomasson

Helium shipments for 1965 exceeded the volume shipped during the previous year for the 16th successive time. Shipments from Bureau of Mines helium plants were 698.6 million cubic feet, 2 about 4.7 percent more than in 1964. Production at Bureau of Mines plants totaled 757.4 million cubic feet, and an additional 3,549.6 million cubic feet was produced by private companies participating in the helium conservation program and purchased by the Bureau of Mines and stored underground for future use. The Bureau of Mines continued to sell helium at $35 per thousand cubic feet, the price established in 1961. Production and sales of helium increased from the one private plant operating entirely outside the Government's helium program. A second private plant was virtually complete at yearend, although actual production had not commenced.

Jan 1, 1967

By P. T. Allsman

INTRODUCTION The honor of being the recipient of the Mining Society's Daniel C. Jackling Award for 1966 imposes on me the responsibility to search for the subject that I would be best qualified to discuss. It seems that my experience in the mineral industry — nearly 15 years in private and 30 years in public employment — should uniquely qualify me to comment upon the relationships between the mining industry, mineral engineering as a profession, and government, and the changing economic, technologic, political and social changes that dictate their relationships. Such conditions, the increasing knowledge of the world mineral resource base, the greater demands of an expanding population with a rising standard of living, shall be evaluated with respect to our profession — mineral engineering. In all of these forty or so years, I have been in close touch with many phases of the mineral and energy resource industries, especially those of the United States. Particularly during the past 10 years, I have had a ringside seat at the "goings on" in Washington. During all of this period I have observed and analyzed many of the problems of the industry and its relations with the government. During the past few years, I have had increased opportunity for doing research and have found a need to learn something about the mathematical techniques that are undergoing such a revival since electronic computers were developed. One of these techniques is multivariate analysis, which is a system for correlating a large number of complex variables. By applying this technique to the seemingly chaotic present-day situation, there emerges a course of steady improvement in the minerals resource industries that wars, depressions, and political strife have failed to obstruct for long. In short, I advocate a need for new concepts in mineral engineering to cope with the changes, pos- sibly adding many more specialized areas on one end of the spectrum, and broad engineer-generalist approaches at the other. The meeting place shall be where the intricate mineral resource problems at the frontier of knowledge merge into the socio-techno-logical problems of the world. HISTORICAL INVOLVEMENT OF GOVERNMENT IN MINERAL RESOURCE PROBLEMS Involvement of government in mineral resource problems undoubtedly is as old as government itself. But passage of the Mining Act of 1866, superseded by the Act of 1872, was the first major entry of our Federal Government into the problems of mining. Passage of the law was necessary to resolve many conflicting claims and disputes in mining. The General Mining Law of 1872 and the Mineral Leasing Laws of 1920 apply to millions of acres of public lands and to certain privately owned land on which the mineral rights have been reserved to the Federal Government. The extensive involvement of government in the mineral industry business today often comes as a shock to the mineral engineer who has begun to climb the ladder to the top in his company. He is often poorly prepared to cope with the situation and becomes frustrated and even hostile. Better knowledge of the role of government perhaps would ease his situation. In our political system, private industry is responsible for producing minerals. To make certain that the production is adequate for a peace-time economy, and to guarantee the Nation's security in an emergency, the Federal Government finds it expedient to develop policy and engage in regulatory, educational, and research activities. A few examples will illustrate the varied role of government in relation to mineral problems. In varying degrees many agencies of the Executive Branch of Government have responsibilities that influence the functioning of the mineral and energy industries. In addition, of course, Congress, the Judiciary, and State and local governments exercise great influence. The Department of the Interior is primarily responsible for activities to promote the development and conservation of mineral and fuel resources, and the

Jan 1, 1967

By Robert C. Bates

Variations in water percolation rates through saturated cohesionless hydraulic backfill (mill tailings) have been studied in relation to the many physical aspects of the system to determine the most important factors in causing these variations. A multivariable least-squares regression analysis of 135 separate tests shows that a reliable estimate of the water percolation rate through typical hydraulic backfill can be made if the bulk density (unit weight), specific gravity, and grain-size distribution are known or can be estimated. Equations for predicting percolation rate, coefficient of permeability, and seepage velocity are developed both for the range of data analyzed and for extrapolation. The prediction equations for use within the range of data studied are quite accurate, while the ones developed for extrapolation are less accurate but still give reasonable approximations of flow rates. The equations given are valid for cohesionless materials that are free of clays and micas, exemplified by classified mill tailings. The equation developed for predicting percolation rates is as follows: 1nP20 = 11.39147 + 2.853422 1n(VR X D10) + 0.1747436 VR X Cu -178.8039 D10 X D50 + 311.7034 (DSO )3, (1) where P20 = percolation rate, inches per hour at 20° C; correction factors for other temperatures are given in the text, VR = void ratio, dimensionless, D10 = effective size (diameter in millimeters of the 10-percent-finer grain size), Cu = coefficient of uniformity (ratio of the diameter of the 60-percent-finer grain size over D10), D50 = average size (diameter in millimeters of the 50-percent-finer grain size), and In = natural logarithm (log to the base e). The prediction equation for percolation rate is rather complicated, so for practical use a nomograph that simplifies the solution of the prediction equation was developed.

Jan 1, 1967

By B. C. Allen

The interface energies of chronzium, molybdenunz. hugsten, and their solid-solution alloys Cv-35Re, MO-33Re, and UJ-25Re were studied at 0.6 to 1.0 of the absolllte liquidus ter)zpe,vature using fiz&apos;e )izethods. Liquid surface tension, yv , was deter mined clsing the pendant-drop and drop-weight methods. Results are, respectizlely, 1700, 2370, and 2480 +100 dynes per ct for the rhernium -containing alloys and essentially the same as tlwse reported for liquid chro)riln, trolybdenum, and tungsten. Average solid slrjace energy, rsv< xias ))zeasured using tlre fiber-extetlsion method. The ratio of ysS, the acerage high-angle grain-boundary energy, to ySV cclas jolnd fronz grain-bolzdary grooue angles fort)zed at the surface in an inert atrfizosphere. Absolllte iute?:face energies were deterawined using ?nultip/rase equilibria involzing suitable liquids of known surface tension (tin, silver). Interpretation of the experimented results in view of pvobable tenzperatzcre, orientation, and purity effects giz,e the follouling approximations in ergs per sq ctn: ysv (i2lo. Mo-33Re) - 2100, ySS (Mo, Mo-33Re) - 800, rr (defornzation twins in MO-33Re at 1200"C) - 800. ysV (Cr. Cr-35Re) - 2400. YSS (CY, Cr-35Re) - 1000. Probably Ylv- YSV- 2500 for tungsten and W-25Re, giving yss (It&apos;, W-25Re) - 900. The interface energies of solid and liqid ch?&apos;omiu?.z, nolybdenu?rr, and tungsten are not geatly aff&apos;ected by rhenium and therefore are not a ttlajor factor in the ductili zing rhenium effect in Croup VI-A metals. THE interface energies of the refractory Group VI-A metals, chromium, molybdenum, and tungsten, are not well-established. The objective of this investigation was to study the liquid surface tension, solid surface energy, and grain-boundary energy of these metals and compare them to those found for the bcc solid-solution alloys, Cr-35e,&apos; 0-33e,&apos; and -25e. Five techniques were used to measure interface energies in high-purity polycrystal rod, wire, and sheet at 0.6 to 1.0 of the absolute liquidus temperature. The alloys were chosen to see if there was any connection between interface-energy behavior and the ductilizing rhenium effecL4j5 EXPERIMENTAL WORK Materials. A description of the materials used is presented in Table I. Chromium rod was prepared by arc melting iodide process crystals supplied by Chromallo Cor., hot extruding, and warm swaging to 0.63-cm-diam rod.6 The sheet was prepared by rolling as-extruded rod to 95 pct reduction in area from a hydrogen furnace at 800" to 900°C and surface grinding off 0.02 cm from each face. Cr-35Re rod was prepared by arc melting sintered rhenium powder and iodide chromium crystals, warm rod rolling to 50 pct reduction in area in cans, and swaging to 60 pct reduction in area at 1100" to 1200°C. Some of the rod was warm-rolled to sheet and then surface-ground. Portions of swaged chromium and Cr-35Re were further reduced by swaging and drawing to 0.013-cm-diam wire by the General Electric Co. Mo-33Re and W-25Re rod, sheet, and wire were provided by Chase Brass and Copper Co. The molybdenum sheet consisted of two lots, both essentially the same except for the carbon content. Liquid Surface Tension. The liquid surface tension of Cr-35Re, Mo-33Re, and W-25Re was measured by a combination of pendant-drop and drop-weight methods using techniques already decribed." Following out-gassing, molten drops were formed on the ends of centerless-ground Mo-33Re and W-25Re rods by electron bombardment at 5 x 106 mm. Similar drops were formed on outgassed Cr-35Re rods by induction heating under 1 atm of 99.995 pct Ar. Solid Surface Energy. Solid surface energy was measured by conducting microcreep experiments on molybdenum, Mo-33Re, chromium, and Cr-35Re wires at 2350°, 2306, 1550°, and 180O°C, respectively. In preparation, gage marks -2.5 cm apart and -0.001 cm deep were circumferentially scribed on the wire with a razor blade. Weights of the wire material were then attached. Five to seven reasonably straight wires were hung in a container made out of the wire material. The free end was placed through a small hole in the removable top and secured by bending a small portion 90 deg. The containers not only tended to provide vapor-solid equilibrium for the wires but also protected them from gaseous impurities. They were nominally 2.5 cm in diam by 5 cm high and were made from extruded chromium rod, Cr-35Re arc casting, molybdenum bar stock, or welded Mo-33Re sheet. After deg re as ing, the assembly was outgassed at a relatively low temperature to 2 x 10"5 mm and then recrystallized 2 to 8 hr at the creep temperature in a rhenium-element resistance furnace. The static argon atmosphere was gettered by tantalum radiation shielding. Specimen temperature was measured optically to 25"C using calibration with known melting points and blackbody conditions. The wires generally developed a stable bamboo-type structure according to Fig, l(b), (c), and (d) and retained their gage marks [upper portion of Fig. l(d)]. One or two of the weights were clipped off to provide a low load for the creep anneal. To minimize the possibility of bending or breakage, the wires remained attached to the top of the annealing container which was held to keep the wires vertical. The distance between gage marks was

Jan 1, 1967

By Glenn E. Johnson

The Bureau of Mines investigated the production of hydrogen cyanide by reacting powdered coal (minus 300 mesh) with ammonia at 1,250° C in a bench-scale study. Both metallic and ceramic reactors were used. Yields up to 0.7 cu ft of hydrogen cyanide per cubic foot of ammonia consumed r- obtained. The resulting ammonia conversion of about 75 volume-percent approximates conversion obtained commercially in processes utilizing natural gas and platinum catalysts. The coals that had higher volatile-matter contents gave the best yields of hydrogen cyanide. Allowing the coal to adsorb ammonia before reaction resulted in increased yields of hydrogen cyanide. Cost studies for a plant with a 40-million-pound-per-year capacity indi-cate that hydrogen cyanide can be profitably coproduced with carbon black, from coal and ammonia, at the current market price of hydrogen cyanide (11.5 cents/lb). These figures are based on heating the reactor electrically. If a cheaper heating method were devised the economics of the process would be more favorable.

Jan 1, 1967

By C. M. McKinney

Sulfur content data from Bureau of Mines routine analyses of 1,060 United States crude oils were used with crude oil production data for the years 1956-66 to prepare tables and charts that illustrate the volume and percentage distribution according to sulfur content of crude oil produced in 10 geographical areas of the United States. Similar relationships for foreign crude oils based on analyses of 201 crude oils and production during 1966 are illustrated for Africa, Canada, Middle East, and South America. Tables are included giving field name, sulfur content, geologic name and age of producing formation, depth of producing formation, and production during 1966 for 882 United States crude oils and 201 .foreign crude oils. Between 1955 and 1966 the average sulfur content of crude oils produced in the United States decreased from 0.73 to 0.67 percent.

Jan 1, 1967

By C. Q. Cupps

n view of increased interest in secondary recovery of oil in the Cut Bank field, Montana, a review has been made of unpublished data obtained during a 1943-44 study of reservoir oil characteristics in this field. Considerable uncertainty was attached to interpretations of subsurface oil sample analyses from six Cut Bank zone wells, one Lander sand well, and one Moulton sand well, because of adverse sampling conditions and wide range in the data. Much of this uncertainty has been removed by this review which has shown two of the Cut Bank zone samples and the Moulton sand sample to be representative of the reservoir oils. Estimates of original reservoir oil characteristics derived from differential-liberation analyses of these samples show that the oil in the Cut Bank zone was initially saturated at the gas-oil contact pres-sure, 750 psia, and the oil in the Moulton sand was undersaturated with a saturation pressure of only 380 psia. The rest of the samples were indicated to be nonrepresentative of the reservoir oils because of a disproportional vaporization of heavier components of the solution gas. The vaporization of these components is believed to be a cumulative effect of contact of the oil with bypassing, light-gravity gas which had been liberated at higher pressures from solution in oil farther back in the formation, or which had come from the gas cap, rather than from the singular effect of gas evolution caused by excessively low bottom-hole pressures. Change of oil composition caused by the latter was found to conform closely to that occurring during a differential liberation of gas in the laboratory.

Jan 1, 1967

By Klaus Schwerdtfeger

The rate of formation of silicon monoxide from silica spheres has been measured at 1500°C in H2, H2-H2O, H2-He, H2-Ar, and CO-CO2 gas mixtures. Indications are that in the hydrogen-containing gases the reaction rate is mainly determined by convective diffz~sion. In the CO-CO2 mixtures the rate approches a constant value which is independent of sphere diometer (and gas velocity). This suggests that a surface reaction becomes rate controlling in CO-CO2 gas. WHENEVER silica is exposed at elevated temperature to a strongly reducing atmosphere there occurs, inevitably, a volatilization of silica by the formation of gaseous silicon monoxide. Because of the importance of this reaction in metallurgical processes and laboratory experiments, its kinetics were studied in the present work. EXPERIMENTAL The spheres made of vitreous silica were suspended by a molybdenum wire in the hot zone of a gas-tight high-purity recrystallized alumina furnace tube of 3.1 cm internal diam and 100 cm length. Molybdenum wire resistance heating was used. A purified H2, H2-H2O, H2-He, H2-Ar, or CO-CO2 gas mixture was passed through the tube, from top to bottom. The amount of silicon monoxide formed was determined by weighing the silica balls before and after the experiments. The silica balls were made from commercially available translucent fused quartz glass. In experiments with hydrogen-containing gases the silica stayed vitreous during the experiment, whereas in experiments with CO-CO2 mixtures, which were performed over longer times, the balls were always crystallized to cristobalite (as determined by X-ray examination) at the surface. Constant-pressure head capillary flowmeters were used to control the composition of H2-He, H2-Ar, and CO-CO2 gas mixtures. The oxygen and water vapor were removed from the gases containing hydrogen by passage through columns containing platinized asbestos (450°C) and an-hydrone. The CO was purified from O2 and CO2 by passing it through activated copper (200°C) and through ascarite. The H2-H2O gas mixtures were prepared by passing purified Hz through a mixture of oxalic acid dihydrate and anhydrous oxalic acid held at a constant temperature in a water bath. The equilibrium water vapor pressures of oxalic acid dihydrate-anhydrous oxalic acid mixtures were taken from the available data.1 The furnace system was checked for sufficient gas tightness at regular intervals. As an additional check, the H2O and CO2 contents were measured in the exit gas and were found to agree closely with the metered contents when H2-H2O or CO-CO2 mixtures were used. When purified H2 was used, H2O pressures found in the exit gas were always below 0.1 mm Hg. These contents originate either from an incomplete reoxidation of silicon monoxide in the cold part of the furnace or from small leaks which cannot be avoided. If the latter is the case, such small uncontrolled H2O contents decrease the partial pressure of SiO in equilibrium with SiO2 by less than about 7 pct, which is considered small in comparison to other experimental uncertainties. The temperature of the furnace was controlled automatically in the usual manner. The reported temperature was measured with a Pl-Pt/l0pct Rh thermocouple and was accurate to ± 5°C. TRANSPORT-CONTROL LED RATE OF REDUCTION The gaseous convective diffusion from the surface of a sphere can be predicted from the semiempirical relationship obtained by Ranz and Marshall2 in a study of the evaporation of water and benzene drops in air. The following equation applies:

Jan 1, 1967

By K. Leutwyler

The key to realistic casing stress analysis in thermal recovery installations is accurate knowledge of the temperatures involved. Much information leading to prediction of heat losses from tubing string to wellbore has been published. This .same information permits calculation of casing temperature under certain conditions. This paper reviews the basis for most of the published work, the line source solution to the diflusivity equation and examines some of its application criteria in the light of unsteady-state conditions. An alternate finite differences method is presented for correlation, and experimental data pertaining to the heat transfer mechanism in the annulus is reported. In the light of the information presented in the paper, it appears that the assumption of a line source for the tubing-wellbore system is valid even for reasonably short periods of heat flow, .such as "steam soak" operations. The empirically modified equation presented earlier matches computer derived results of the finite differences approach lor periods as short as 50 hours. Previously predicted cas ing temperatures and the associated stress levels are thus verified based on these correlative computations and the reported experimental information. Fall out from the computer output resulting in some studies of the influence of insulating cement properties on casing temperature, and experimentally studied effects of nitrogen placed in the annulus at various pressures., are described. INTRODUCTION Generally speaking, predictions of average casing temperatures have been based on an idealized model involving a centralized tubing string at uniform constant temperature radiating energy towards the casing under steady-state conditions.&apos;. &apos; Heat is transferred away from the casing to the formation by unsteady-state conduction across thermal barriers consisting of cement and the mud sheath. Heat balances written on the casing permit prediction of instantaneous casing temperatures. During early periods of injection, casing temperature varies appreciably as a function of time; however, for long injection times this variation decays as heat flow from the wellbore to the formation stabilizes, and it becomes virtually negligible as conditions surrounding the wellbore become quasi-steady-state (Fig. 1). Carslaw and Jaeger -escribe a solution to the diffusivity equation for a line source (Fig. 2). A constant supply of heat is introduced into the medium from the line placed into the origin of the x-y coordinate system and parallel to the z-axis. Heat spreads outward in the infinite cylindrical solid and the temperature increase on a line going through point (x, y) parallel to the z-axis at a distance r can be predicted by: The following criterion must be considered: the Carslaw and Jaeger equation is obtained on the basis of a large

Jan 1, 1967

By D. W. Peaceman

In previous papers by this author on numerical calculations of multidimensional miscible displacement, some simplifying assumptions were made in writing the dispersion term of the differential equation. It was assumed that the flow vectors were essentially parallel to the x-axis. However, in most multidimensional miscible displacements, the flow vectors are not so simply oriented with respect to the coordinate axes. This paper derives the correct dispersion term /or the more general case; gives a difference approximation /or the dispersion tern; and derives the stability criterion for the corresponding explicit difference eguation.

Jan 1, 1967

An attempt was made to determine the lateral extent of analcite in the Newcastle Coal Measure sediments of the Sydney Basin. From an examination of the cores of eleven bores it was concluded that the mineral is concentrated in the western sector of the original Newcastle Basin and this presumably was the region of greatest sodium concentration and aridity. The distribution of the analcite is such that it appears to have little correlative value.

Jan 1, 1967