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By H. E. McKinstry

LIKE nearly everything else, mining geology has been reconverting. Many geologists had been in military and other government service. Many more, with mining companies, had been working primarily toward increasing production from known reserves. All of these are turning now toward their normal peacetime endeavor-the search for new ore; for most mining companies, finding themselves with accumulated deficits in development work, are more than ready to go ahead with their postwar plans made a year or more ago but still stalled at the close of 1945 for lack of man power. These plans include not merely development in the old home camp but also wide exploration for new prospects both domestic and foreign. Most of the large concerns have geologists and engineers in the field in the United States, despite the outlook for higher mining costs here, and at least half a dozen strong American companies are already investigating opportunities abroad, notwithstanding past unhappy experiences in certain Latin-American nations which have welcomed capital but later found means of preventing investors from reaping the reward of their enterprise. A few of these new foreign expeditions are following well-planned programs, but too many, in their haste to get any sort of footing, are proceeding without well-considered policy. with the result that their geologists can do little more than desultory scouting.

Jan 1, 1946

By Hans Lundberg, Basil T. Wilson, H. Steuart Scott

FOR the benefit of those readers who may not be in close touch with present practices in the geophysical prospecting for ore, brief reference will fiat be made to the advantages and shortcomings of the methods to be discussed. Magnetic and electric methods are generally accepted as the most useful for ore prospecting. By magnetic methods, magnetic intensities that are not normal may be recorded and outlined. From these can he located concentrations of such highly magnetic minerals as magnetite or pyrrhotite, which sometimes occur in such large masses that they are of economic value in themselves. More often. however, these magnetic min¬erals are associated with others, such as copper, zinc, lead, gold, and silver, which, if existing in sufficient concentration and quantity, may constitute valuable ore bodies. It is therefore only when pyrrhotite and magnetite are present in these bodies that the magnetic method can be used to indicate their presence.

Jan 1, 1945

By Morris Cohen, Robert C. Ruhl

Fe-Ni-B alloys were inresligated by X-ray diffraclion after splat quenching. Although this rapid cooling did not produce a measurable supersaturation of dissol1ed boron in either binary Fe-B or Ni-B alloys, a marked increase in dissolved boron was achieved by the splal quenching of lernary Fe-Ni-B alloys. Boron additions up to 2.0 wl pcl to Fe-13Ni and Fe-24Ni alloys cause an increase in retained austenite from 0 to 59 pet and to 92 pet, respectively. The martensitic phase in the Fe-13Ni-9 at. pct B alloy is .found to conlain about 0.6 at. pet interstitial boron, as evidenced by the tetragonality of this phase, and about 3.6 at. pct substilutional boron, us deduced from the lattice paratrieler decrease, the balance of the boron being precipitated as (Fe,Ni)aR. The austenitic Fe-Ni-B plznses also contain both interstitial and substitutional boron. Iron-Boron System. The phase diagram and related information about the solid solutions and intermediate phases in the Fe-B system are given by ansen,' Elliott.2 and Pearson.1 The equilibrium solid solubility of boron in both ferrite and austenite is quite small: the maximum solid solubility of 0.02 wt pct B (0.11 at. pct B) occurs in iron at the eutectic temperature of 1150°C. while the maximum solubility in a iron is less than 0.01 wt pct.l There is disagreement in the literature as to whether these solid solutions are substitutional or interstitial. Based on the measured activation energy of boron diffusion in iron, it appears likely that boron moves interstitially in austenite. 4 However, this observation does not rule out the possibility that some of the dissolved boron may also occupy substitutional sites in this phase. Investigations of internal friction of boron in iron have suggested that boron is interstitial there.' Shevelev, 5 on the other hand, reports a decrease in the ferrite lattice parameter with dissolved boron content, thus indicating a substitutional solution. Unfortunately. Shevelev's methods and analysis are unclear. Goldhoff and spretnak6 have measured the lattice parameters of pure iron and an Fe-0.005 wt pct B (0.027 at. pct) alloy at both room temperature (ferrite) and from 920° to 1200°C (austenite). They reporte: a lattice contraction in the ferrite of 0.0003 ± 0.0002 due to boron, thus indicating a predominately substitutional solution. Appreciable (0.0010 to 0.0060) lattice contractions were found in boron-containing austenites, but these effects were much larger than could be accounted for by the substitutional solution of all the boron present. Nickel-Boron System. Elliott 2 gives a summary of thephase diagram and recent work on this system. The solubility of boron in nickel reaches a maximum of 0.03 wt pct at the eutectic temperature of 1080°C. Iron-Nickel System. ansen' presents the equilibrium diagram for this system and also discusses the metastable austenitic and martensitic phases along with the a=? transformations. The lattice parameters of Fe-Ni ferrites have been recently redetermined by Abrahamson and Lopata.7 Their data, Fig. 1, show an unusual change in slope at about 1.7 at. pct Ni. Very few measurements of the lattice parameters of Fe-Ni martensites are available in the literature. The values of Roberts and Owen8 are considerably higher than those measured in the course of the present work: they find that a, is constant at 2.874? from 8 to 30 at. pct Ni. Both the slope change in the ferrite parameters and the occurrence of a maximum plateau in the marten-sitic lattice parameters vs composition denote the

Jan 1, 1970

By R. A. Burmeister, G. P. Pighini, P. E. Greene

An open tube vapor phase epitaxial growth system has been used for large area (multiple substrate) growth of GaAs1-xPx on GaAs substrates. The GaCl-GaCl transport reaction is used with either a GaAs or Ga (nonsaturated) source. Selenium and tellurium have been used for donor impurities, and zinc as an acceptor. The useable substrate area in this system is approximately 20 sq cm. The uniformity of thick-ness of the epitaxial layers are typically better than ±5 pct across a given wafer. Electrical and optical measurerments indicute comparable uniformity in electrical and luminescent properties within a wufer. The application of this system to the large scale pro-duction of GaAs1-x Px for display devices, both discrete and arrays, is discussed. Typical electrical and luminescent properties of light emitting diodes fabricated front material produced by this technique are presented. THE most promising materials currently being utilized for visible injection electroluminescence are GaAs1-xPx, Ga1-xAlxAs, and Gap. All have reasonably efficient emissions in the red portion of the visible spectrum at room temperature; Gap also has an efficient green emission.' At present, GaAs1-xPx has a technological advantage over Ga1-xAlxAs and Gap for display applications, since relatively large (several sq cm) areas of GaAs1-xPx suitable for use in electroluminescent devices may be readily grown by vapor phase growth techniques. In contrast, the preparation of Gap and Ga1-xAlxAs for electroluminescent device applications generally employs solution growth techniques which are at present not well suited for the growth of large areas of uniform thickness and doping level. The capability of uniform growth over large substrate areas and the use of multiple substrates is necessary for the practical utilization of electroluminescent devices. This is particularly important when quantity production or monolithic devices are required. Furthermore, in many display applications arrays of light emitting devices are used, the individual elements of which are of a size resolvable by the unaided eye. Thus the overall dimensions of display are substantially larger than those of most semiconductor devices. It is also necessary to achieve a high degree of control over the growth parameters to attain the required degree of reproducibility of materials properties for electroluminescent devices. In the case of GaAs1-xPx it is necessary to accurately and precisely control the phosphorus content of the alloy, both on a macroscopic and microscopic scale, in addition to the parameters generally associated with epitaxial growth such as thickness and doping level. This value is critical, as it has a major effect on the performance of electroluminescent devices. This paper describes the epitaxial growth of GaAsl-xPx suitable for electroluminescent display devices using a system developed specifically for this purpose, and which contains several novel features. The results of studies of selected physical properties of the epitaxial layers are also discussed. Finally, a brief summary is given of the characteristics of display devices fabricated from GaAsl-xPx grown in this system. EXPERIMENTAL A) Reactants. A number of techniques suitable for the vapor phase epitaxial growth of GaAs1-xPx have been reported in the literature.'-' The method selected for this investigation is that in which the Ga is transported by the GaC1-GaCI3 reaction in an open tube process. The results reported here were obtained using either the combination of GaAs, AsC13, and pH3, or Ga, AsH3, pH3, and HC1 as the initial re-actants.* The ASH3 and pH3 were obtained as dilute *Several different sources of supply were used for these reactants, y~elding comparable results._____________________________________________________ mixtures in HZ; the HC1 was obtained from the reduction of AsC13 by Hz at elevated temperatures. Both selenium and tellurium were employed as donor impurities, and zinc as an acceptor impurity. Selenium was introduced in the form of H2Se, tellurium in the form of tellurium-doped GaAs, and zinc in the form of diethy1 zinc. B) Apparatus. The prinicipal difference between the apparatus used in the present study and that of Tietjen and Amick,8 in addition to size and other related design features, is that RE induction heating is utilized in place of resistance heated furnaces. Induction heating was selected for this application because it appears to have several advantages, including: 1) It is possible to keep all fused silica portions of the apparatus at temperatures well below those of the reaction zone, thus minimizing a possible source of contamination. 2) The thermal mass of an induction heated system can be made small, thus reducing the total time required for the growth process. 3) Sharp temperature profiles (desirable for high deposition efficiency) are easily achieved. 4) The volume of the system for a given substrate area can generally be made smaller than a comparable resistance heated unit. This results in shorter time

Jan 1, 1970

By D. C. Sisti

A technical evaluation of actual performance of the preparation facilities at Beaver Consolidated Coal Co.'s Stinson plant is presented, with special emphasis on sulfur reduction in 1-1/2 x 3/8 in., 3/8 in. x 28 mesh, and 28 mesh x 0 size fractions. Evaluation of the heavy medium section of the plant and the treatment of the 28 mesh x 0 coal is included. Design criteria considered for sizing and selection of equipment required to process 1-3/4 million tpy of raw coal on coals of divergent washability characteristics are summarized.

Jan 1, 1976

By D. E. Mikkola, G. E. Poquette

X-ray diffraction was used to study the growth of antiphase domains in quenched (or "disordered&apos;? Cu3Au annealed in the range 300" to 385°C. Measurements of the long-range order parameter indicate that a high degree of order is established rapidly at these annealing temperatures. Average domain sizes obtained by Fourier analysis of the superlattice peak profiles show that antiphase domain growth is analogous to classical metallurgical grain growth (i.e.,fol-lows a D2 US kt relation). The activation energy for the growth process, 44 kcal per mole, indicates diffusion control. The anisotropy in the observed effective domain sizes from seven different superlattice peaks can be best accounted for by a configuration involving antiphase domain boundaries on {100 } and (111 ) planes, where the (100) boundary is the low-energy type, {lOO} Type I. The disappearance of the (111) antiphase domain boundary during domain growth is dif-fusion-controlled with an activation energy of 48.5 kcal per mole. On the other hand, the behavior of the parameter representing the amount of (100) Type I boundary indicates that there may be a conversion of the higher-energy boundary types to (100) Type I boundary during the growth process. THE order-disorder transformation in the alloy Cu3Au has been the subject of numerous experimental investigations over the past 40 years, most of which have involved measurements of convenient physical properties such as resistivity and hardness as a function of heat treatment. The interpretation of these data is difficult because measurements of this type have the disadvantage that they yield total changes resulting from several different atomic processes which may be occurring simultaneously. The present study was undertaken to establish by means of X-ray diffraction the kinetic behavior of one of these atomic processes, namely antiphase domain growth. In the completely ordered state Cu3Au has an L12 structure which can be described as an fcc type arrangement of atoms in which the gold atoms occupy the corner sites and copper atoms the face-centered sites. Three other equivalent unit cells can be formed by allowing two gold atoms to occupy opposite face-centered sites and copper atoms to occupy the remaining corner and face-centered sites. These four different unit cells are crystallographically related by a shift of 1/2<110>. Quenching from above the critical temperature (392°C) to room temperature retains the "disordered" structure-a "random" arrangement of copper and gold atoms having the fcc structure. Annealing the disordered alloy below the critical temperature causes ordering to occur through the nucleation and growth of ordered regions at different points throughout the crystal. These small ordered regions, each based on one of the four types of unit cell, grow by consuming the disordered material until they impinge to form a domain structure in which the domains are antiphase by a shift of 4(110). The boundaries between domains are called antiphase domain boundaries (APDB) and they have been found to lie primarily on &apos; {100} planes in highly ordered Cu3Au. Two types of APDB can occur on ( 100) planes. An example of an (001)1/2[110] shear type APDB is shown in Fig. I. Because of the layer of copper atoms separating the domains in this case, there are no near-neighbor violations across the boundary and it has a low surface ener This type of APDB will be referred to as {lOO} Type I. Fig. 2 shows an (001): [011] climb type APDB, (100) Type 11. This type of APDB can be described as resulting from removal of a (200) plane followed by a shift of 1/2<110> to bring the separated regions together. Near-neighbor violations across (100) Type I1 APDB make it a high-energy boundary. There are numerous other possible APDB configurations; however, it is only worth noting that shear type APDB can be produced on the (111) plane by motion of a normal fcc dislocation with Burgers vector 1/2<110> through the ordered structure. A (111); [110] shear type APDB is shown in Fig. 3. Again, because of the near-neighbor violations this type of APDB has a higher energy than the (100) Type I APDB.

Jan 1, 1970

By Ernest A. Hersam

IN every commercial establishment,&apos; it is customary and necessary to take inventory, periodically, and to account for profits and detect losses, to achieve productiveness and enhance efficiency. So, too, in the ordered life of every individual, there is the need of periodic introspection. The exercise of the Sabbath for rational thought, the utilization of pause, or rest, from the technique of daily occupation, orient the efforts. These are the constructive opportunities by which we grow always better than we were. Thus, also, there&apos; is need of a periodic analysis of the organizations to which we belong and toward which we con- tribute. So we find&apos; reason for the fitness of our loyalty. There seems to be no half-ground for the engineer. Whatever presumes to bear his name demands either the crushing pressure of his heel or the supporting pressure of his hand.

Jan 1, 1929

By Stanley L. Lopata, Eric B. Kula

The problem of preferred orientation has been considered in quantitative phase analysis by X-ray diffraction techniques. The average intensity of a diffraction peak can be obtained by integration over the whole pole figure, or by random rotation of the specimen in the X-ray beam, or by a combination of both. For rod or wire, where the pole figure shows rotational symmetry, the intensity is measured along a radius of the pole figure. Where no symmetry is present, rotational symmetry is imparted by rapid rotation of the sheet around its surface normal during measurement. These methods are applied to the determination of aus-tenite in an Fe-31 pct Ni rod and Fe-28 pct Ni sheet. X-RAY diffraction techniques are frequently used for quantitatively determining the relative amounts of two or more phases present in a structure.1,2 Briefly, the method requires a measurement of the intensity of a Bragg reflection for each phase. The method is based on the principle that the intensity of a Bragg reflection, IA, is directly proportional to the volume fraction of the given phase present, CA: T KRACA/2µ [1] where K is a constant independent of the diffracting phase, RA can be calculated and depends on the Bragg angle ? and the particular reflection measured, and µ is the linear absorption coefficient of the mixture.&apos; For a mixture of two phases A and B, IA = RAcA [2] IA/IB=RAcA/Rbcb and CA+ CB = 1 [3] This allows the volume fraction of a phase to be calculated directly from the measured integrated intensities of the two phases present. This method is frequently used for quantitatively determining retained austenite in steels, but can be used for the quantitative determination of in titanium alloys, as well as phases in other alloy systems. The intensities are generally measured by diffracting only from planes whose normals are perpendicular to the specimen surface, with the implicit assumption being made that this intensity is typical of reflections from planes whose normals lie at other angles to the surface. If the specimen contains a texture or preferred orientation of the crys- tallographic planes by virtue of previous mechanical working, however, this measured intensity is correct only if the intensity level fortuitously is one times random. Examination of pole figures for actual rolled sheet shows that the intensity level at the center of the figure is seldom at the random level, and can very easily differ by a factor of five or more, leading to a commensurate error in the calculated amount of the phases. Textures have been commonly found in materials which are cold-rolled or recrystallized after cold rolling. This problem is becoming of greater importance since structural materials in use today, such as the high-strength stainless steels, frequently are further strengthened by cold rolling, and hence contain textures. Although high-strength carbon-containing alloy steels generally do not contain textures, some of the newer thermomechani-cal treatments will impart a texture even in these cases. In the case of hexagonal metals, such as titanium, probably every wrought sample will show some anisotropy. Since the standard X-ray techniques are inapplicable in all these cases, there is a clear need for some method of taking this anisotropy into account. The specific problem is to obtain the integrated intensity of a Bragg reflection for each phase, averaged over all orientations of the sample with respect to the X-ray beam. This can be done either by purely mechanical means or by a mathematical averaging. Mechanically, a small spherical speci-

Jan 1, 1965

By A. E. Jenkins, L. A. Baker, N. A. Warner

Rates oj decarburization of levilated Fe-C droplets conlaining 5.5 to 0 pct C have been measured at 1660°C. Gas mixtures of 1, 10, and 100 pct 0, with helium diluenl were used at velocities of 12.5 and 62.5 cm per sec. Rates were independent of carbon concentration in the mell and in good agreement with the calculated rule of oxygen diffusion through the gas boundary layer. The effects of flow rale and total pressure are as predicled and the rates are approxitnalely 2.5 times those with CO2 as oxidant. The mass-transfer correlation used incorporaled the efject of natural convection as well as forced conrection. Graphile spheres are shown to oxidize at the same rate as Fe-C droplets under the same experimental codlions. It is concluded that, for high carbon concentrations in the melt, the rate of- decarburizalion is controlled wholly by the rate of gaseous diffusion. Rate measurements with pure CO, are reported for low carbon concentrations where CO bubbles nucleate within the droplet. Under these circumstances the decarburi-zation decreased with carbon concentration and it is proposed that carbon diffusion is significant in conlrolling the decnvburization rate. In an earlier paper1 decarburization rate measurements were reported for levitated Fe-C alloys at 1660°C but with CO2 as the oxidant. The decarburization rate was found to be independent of carbon concentration in the melt but slightly affected by total pressure. The authors were unable to explain the slight pressure effect but in all other respects the results were consistent with control by diffusion in the gas boundary layer. Subsequent work has been directed at finding the reason for the slight pressure effect and whether the kinetics with oxygen as oxidant parallel those with CO2. Recently Ito and Sano2 have shown that with water vapor-argon atmospheres the decarburization rate is gaseous diffusion controlled until an oxide film appears on the surface. In this work the melts were contained in crucibles. MASS TRANSFER IN THE GAS PHASE In the earlier analysis1 only forced-convection mass transfer was considered. Subsequent recognition of the existence of some free-convection mass transfer explained the observed small effect of total pressure on the decarburization rate. Steinberger and Treybal3 and Kinard, Manning, and Manning4 have developed correlations involving the linear addition of the contribution of radial diffusion, free and forced convection. Steinberger and Treybal&apos;s correlation was chosen as the most applicable to the present work since it correlated most of the data available in the literature and handled the low Reynolds number region exceptionally well. The correlation for (Gr&apos;Sc) < 108 is where Nu&apos; is the Nusselt number for mass transfer based upon the total surface of a sphere in an infinite medium, G&apos; is the mean Grashof number for mass transfer defined by Eq. [2], Sc is the Schmidt number (µ/pDAB)f, Re is the sphere Reynolds number (dpu,pf/µf), p is the viscosity of the gas (poise), p is the density of the gas (g cm-3), Dab is the binary diffusivity for the system A-B (sq cm sec-&apos;), dp is the sphere diameter (cm), u is the approach velocity of the gas (cm sec-I), and subscript f denotes the property value is computed at the film temperature Tf defined by Tf = +1/2(To + Tr) where To is the specimen temperature and T, is the approach gas temperature (oK). Natural convection occurs when inhomogeneities exist in gas density. These may be caused by concentration gradients, temperature gradients, or both. In the present work the temperature gradient between the sphere and the bulk gas was very large and in some cases, for example the runs with pure oxygen, the concentration gradient was also appreciable. The Grashof number defined by Mathers, Madden, and piret5 was used since it took account of both temperature and concentration gradients: where Gr&apos; is the Grashof number for mass transfer (p2fgd3|-yA-yA|/µ2f), Gr is the Grashof number for heat transfer (p2f gd3p|To - T,]/µ2fTf), Pr is the Prandtl number (cpµ/k)f, g is the acceleration due to gravity (cm sec-&apos;f, a is the concentration densification coefficient (1/p)(ap/ayA)T, yA is the mole fraction of component A at the gas-metal interface, yA is the mole fraction of component A in the bulk gas stream, cp is the heat capacity of the gas per unit mass at constant pressure (cal g-I OK-&apos;), and k is the thermal conductivity of the gas (cal cm-&apos; sec-1 OK-1). Mathers et al. tested this combined Grashof number

Jan 1, 1968

By Frank J. Windolph

Grinding Practice-These tests were run in the 9 ft diam by 8 ft long grate discharge ball mills at Climax. Each mill functions in closed circuit with a 78 in. Akins duplex high-weir classifier, and a circulating load of 300 pct is maintained. The size of the mill feed is 6 pct on 3/8ths, which is ground to pass 28 mesh. Testing Methods-Each grinding section is equipped with a conveyor scale on the ball mill feeder belt, a watt-hour meter on the ball mill motor, and an automatic sampler for the ground product. These instruments are exceptionally valuable to the mill testing program.

Aug 1, 1956

By Claude P. Heiner

mountain region to M tht Coast points for domestic consumption and for export are shown in Table 11. There is considerable disparity in rates from both Rock Springs, Wyo., and Castle Gate, Utah, to the four coast cities where the slack coal is to be used for purposes other than export. The rate on coal to be exported is the same from either starting point to any of the four coast cities even though there is a difference of as much as 341 miles in the shipping distance. It is interesting to note that the freight rate between Sunnyside, Utah, and Fontana, Calif., on coking coal is $5.05 per ton and that coal up to 8 in. can be moved on this rate if it is suitable for coking. This rate was published late in 1942 on a contemplated annual movement of more than 500,000 tons. There have been decreases in freight rates since 1923 on movements of slack coal from Utah into Seattle and Portland due to pressure on the railroads and to greater. quantity of coal shipped. It is the author,&apos;, opinion that a movement of slack coal in excess of 3 million tons of coal per year from Utah to any point in central California would justify a freight rate equal to that puhlished for Fontana, Calif.. or $5.05 per ton. The movement of 3 1/2 million tons of coal per year on the basis of 240 mine working days per year would require that 14,600 tons be handled each mine working day. If it is assumed that shipments could be arranged for a 6-day week, the average railway movement would he 11,200 tons, or approximately 3 trains containing fifty-five 70-ton coal cars per day. Such movements of coal would require railroad equipment represented by the investment amounts stated in Table 12 and entail the services of 250 men. Table 12 ... Railroad Equipment and Investment Required To Move 11,200 Tons of Coal a Day from Utah to California Railroad Equipment Cost 2800. 70-ton coal cara at $6.000 each $16,800.000 32 locomotives at $310.000 each. 9.920.000 Miscellaneous eauiument:.......... .5;000:000 Total........................ $31,720,000 It therefore appears that, under presently known mining methods, the lowest price at which coal could be sold f.0.b. the mine in amounts of 3 1/2 million tons per year for generation of power in central California would be $4.60. It also appears that the lowest freight rate that could be expecled between intermountain points and the central California area would be $5.05 per ton, making a total cost of coal delivered at a plant site of $9.65 per ton. Conelusions The following are the author&apos;s conclusions: 1. Coal mines in Utah and in the Kemmerer and Rock Springs districts of Wyoming could increase annual production by 6 1/2 million tons per year. 2. Under present conditions coal could probably be delivered to any steam electric plant in central California at a price not to exceed $9.65 per ton. 3. The use of coal at such a price, while higher than the equivalent present price of fuel oil, is entirely feasible. 4. There are adequate railroad facilities for movements of large quantities of coal from the intermountain region to the Rest Coast. 5. In a national emergency it probably would be extremely difficult, if not impossible, to obtain sufficient oil to meet requirements of the greatly expanded West Coast steam electric generatsing capacity. 6. The intermountain region contains ample coal reserves to supply all conceivable demands for West Coast power generation for a number of generations. 7. Increasing demands of labor threaten to lessen, if not eliminate, savings in cost of coal production through the use of new mining machinery. 8. Continuation of experiments in socialism by the Federal Government through construction of hydroelectric generating plants, particularly those unrelated to land-use reclamation, defies justification. Rates under this concept of a governmental function are subsidized through greater taxation of its people. Private capital is available to construct steam plants, or hydro plants where feasible, and should be permitted to continue in order to preserve the principles of our free enterprise system. DISCUSSION (L. C. McCabe and Robert P. Koenig, presiding) C. C;. BALl*—I was asked to lead off the discussion, but it is not with the thought that I might be able to add anything to the paper. The thoroughness with which it was prepared rather forestalls the asking of many questions. Your treatment, Mr. Heiner, is a very valuable contribution. I do want to suggest—that although you have limited your study to this specific question, with certain geographic limitations, many of the things in your paper apply just as well to the eastern coals. I want to agree 100 pct with your final conclusion concerning government-subsidized construction. Id. C. McCabe*—It is certainly worthwhile to take stock occasionally to see where we are going in problems of this nature. I agree with Mr. Heiner that ultimately the only reliable source of fuel that the West Coast has is coal hut the time factor is the difficult element to evaluate. Just before I came here I discussed this subject with N. B. Hinson, Vice President and Executixe Engineer of the Southern California Edison Company, and Chairman of the West Coast Inter-Power Exchange Committee. He has given much thought to utilities&apos; fuel supply and it was very helpful to me in preparing a discussion of the paper to talk with him beforehand. Stock taking and forecasting of future development are essential to the continuing success of any enterprise. Mr. Heiner has called attention to the unprecedented growth of central and southern California and to the increased demands for fuel and power which have accompanied it. He discusses the increased fuel oil and natural gas requirements and the probable limits on the future use of these fuels and of hydroelectric power. In contrast to the calculable limits of these sources of electric energy, the author points to the availability of enormous reserves of coal in the Rocky Mountain States adjacent to the Pacific Coast which can be utilized for power generation. That there will be increased use of coal for power generation in the area under discussion is generally accepted hut it is in the timetable of such development that there is not complete agreement. In a recent report, Mr. Hinson reviewed the future power outlook for the Pacific southwest area. He pointed out that the use of steam plants in connection with water power plants in this region has made the maximum use of hydroelectric energy possible, and that the correct balance between hydro and steam generating plants produces the most economical overall system. Steam plants in the area which had been installed to protect against deficiency in hydro energy in dry years were used to carry war loads. Fortunately, no dry

Jan 1, 1950

Iron Ore Resources of the World (Die Eisenersvorrate der Welt)_ By G. Einicke. Verlag Stahleisen, Dusseldorf, 1950. 418 p., with 192 tables and an atlas volume containing 100 p. of reaps. 66 German Marks.-A notable work in which the latest available information on iron ore deposits has been compiled by diligent work, continent by continent, country by country. The author reveals the effect of geological formations, iron content of ore, accessability, cost of transportation, political and economic considerations. Ore beds of importance to the German iron and steel industry are given more space than others. The bibliography contains almost 250 references. A tragic comic feature is the author&apos;s complaint that as soon as a map of iron ore resources of a country has been completed, the country&apos;s boundaries are changed. Reviewed by W. Trinks, Carnegie Institute of Technology. Industrial Research Laboratories of the United States. National Research Council, Washington, D. C. Ninth Edition. 1950. 445 p. $5.-Contains information on the research laboratories of 2845 industrial and commercial organizations, including names of research executives, location of labs, types of activity, whether any consulting services are offered. There are two appendices, one of which lists data on government labo ratories which cooperate with industry, and the :)ibex naming universities and colleges offering research services to industry.

Jan 2, 1951

By J. N. Ong

The oxidation of tantalum is assumed to occur by four simultaneous first-order chain reactions; solution of oxygen in the metal, nucleation and growth of a suboxide phase at the metal surface and two phase boundary processes which give rise to two different modifications of Ta2O5. A rate equation is then formulated which accounts for all principal details of oxidation behavior, unifies and correlatss the results of the principal investigations, and expresses the rate as a function of pressure, temperature, and time. For purposes of practical application, the expressions: may be used below and above 700T respectively to determine the regression rate of tantalum in cm per hr, where T is to be expressed in "K and P in atmospheres pressure of oxygm. The equations will reproduce within a factor of two all reported experimental rates in the temperature range 475" to 1400°C and pressure range 0.000026 to 40.8 atm 0. 1 HE oxidation kinetics of tantalum have been investigated thoroughly in the temperature range 50" to 1400 and pressure range 1.32 x l0-&apos; to 40.8 atm pressure of 0,and as a result, the principal features of the oxidation of tantalum are known and have been described in considerable detail. The exposition of the characteristics of the behavior of tantalum in oxygen has been largely descriptive, with considerable attention being devoted to elucidating the structure, composition, and morphology of the resulting oxide products. The weight change vs time results have usually been reported graphically. With the exception of the linear rate below 700 C and the process of diffusion of interstitial oxygen into the metal,6&apos;9 no effort has been made to characterize the reaction rates in functional form. It is the purpose of this paper to demonstrate that when the fundamental principles of chemical kinetics are rigorously followed, the results of the principal investigations will be correlated and unified and the oxidation rale may be expressed as an analytic function of pressure, temperature, and time. In addition to accounting for the temperature and pressure dependency of the oxidation rate, the following minor features will be accounted for as a result of the basic analysis: the initial period of nonline-arity in rate at low temperatures, which decreases with increasing temperature;3&apos;5&apos;7 the rate vs temperature cusps obtained at constant pressure"5 the concentration gradient of oxygen interstitially dissolved in the metal.5&apos;7 The analysis will also be consistent with the overall chemistry of reaction and with all visual, microscopic, and X-ray observations. DEVELOPMENT OF RATE EQUATION As a fundamental basis for the treatment of metal-oxygen reaction kinetics, it will be regarded that the rate of reaction is determined by the concentration and not the activity or chemical potential. It is further assumed that all metal-oxygen reactions are first order complex chain reactions" whose rate is dependent on the concentration of an intermediate species which is a complex function of the oxygen concentration, or oxygen pressure, only. The basic rate equation is therefore: is the weight of oxygen consumed by the reaction, A is that portion of the area of the metal over which the reaction is occurring (cm2), t the time (sec), kf the rate constant for forward reaction, C the intermediate species concentration and f &apos;([Oz]) and f (Po,) are complex functions of oxygen concentration and Oxygen pressure respectively. Reverse reactions may usually be neglected in metal-oxygen systems since a large negative free energy generally accompanies these reactions. Eq. [I] takes different forms when the rate of reaction is controlled by diffusion into or through a phase or at a phase boundary. For diffusion into the metal phase, the rate is given by1&apos; Di is the diffusion coefficient of species diffusing into the metal phase (cm2/sec), and Q is the corre-

Jan 1, 1962

By J. H. Schulman, M. H. Buckenham

Although much interest has been taken in the use of mixed collectors in flotation, this investigation is probably the first in which oppositely charged collectors have been considered. The results obtained and the techniques used could well be applied in the behavior of other mixe the behavior of other mixed collector systems and could possibly explain the effective flotation results which have been reported when various collector combinations have been used. Collectors conventionally employed in flotation systems are soluble in water, but many of their homologs of longer hydrocarbon chain length are insoluble. The properties and behavior of these insoluble compounds may be conveniently studied when they are spread as monolayers at the air/water interface on the Langmuir-Adam trough. Although some extrapolation is involved in applying effects observed at this interface to the solid/liquid interface where the action of collectors is most important in flotation, the technique nevertheless is most useful for the study and interpretation of flotation phenomena. Of particular interest in this field are investigations on the insoluble monolayers of the fatty acids, alkyl sulfates and alkyl amines; the penetration of these insoluble monolayers by soluble surface active components and their interaction with metal ions from the underlying solution.&apos;-&apos; Unfortunately, the insoluble xanthates and related compounds do not exhibit stable monolayer properties due to rapid oxidation at the air/water interface and, therefore, cannot be studied directly in this way. These approaches have enabled Leja and Schulman8 to suggest mechanisms explaining dynamic attachment of mineral particles to air bubbles involving collector-frother interaction and the adsorption of collectors onto mineral surfaces. In this and other papers 9-12 considerable evidence is presented to support the concept of collector-frother and metal ion-monolayer interaction and to emphasize the value of monolayer techniques in elucidating the flotation system. Molecular interactions resulting from monolayer penetration are determined by the nature of and the association between both the polar and nonpolar groups of the two molecules concerned. Stable complexes are formed on penetration when interaction takes place between both the polar and nonpolar groups, and although the resultant complexes are not necessarily true chemical compounds, the properties of the molecularly associated complexes are very different from those of the individual components. Shortening of, or changes from, a straight hydrocarbon chain in one of the reacting molecules reduces considerably the stability of the associated complex as do changes in temperature, pH and substrate composition. The effect of hydrocarbon chain length becomes most important when observed effects are to be applied in flotation studies where soluble homo-logs and, therefore, much shorter hydrocarbon chain lengths are used. The present investigation is based on Langmuir trough work carried out by Bowcott,l3 who studied the penetration of insoluble amine monolayers by potassium lauryl xanthate. Bowcott observed that cetyl amine monolayers were readily penetrated by xanthate, but found that with time the high film pressures resulting from penetration and association fell off, indicating decomposition and ejection of xanthate from the film. This decomposition was pH dependent. Of particular interest in this work were studies on an equimolecular mixed monolayer of the fully N-substituted ammonium compound, for example, cetyl trimethyl ammonium iodide (CTAI) and potassium cetyl xanthate. Despite the fact that the CTAI is water soluble and the xanthate on its own is incapable of forming a monolayer, the mixed film was stable up to a surface pressure of 67 dynes per cm. In this condensed state the xanthate was stabilized against atmospheric oxidation, although iodine injected beneath the film caused an immediate collapse. The stabilizing of xanthate against oxidation by association with an alkyl trimethyl ammonium bromide (TAB) could be important in flotation, and a study of the performance and behavior of mixed collectors therefore was undertaken. A modified Hallimond tube operated under controlled conditions was used to evaluate flotation. Surface tension measurements were made to investigate the properties of the soluble

Jan 1, 1963

By S. S. Marsden, S. H. Raza

An experimental study of the flow of line-textured. aqueous foams through Pyrex tubes is described. The foams range in quality F (ratio of gas volume to total volume) from 0.70 to 0.96 and behave like pseudoplastic fluids. At lower flow rates they exhibit laminar flow ad have apparent viscosities which increase with quality, and which cover a range of 15 cp to 255 poise for tubes of 0.25- to 1.50-mm radius rj. At higher flow rates a plug-like type of flow is developed, the extent of which increases with both T and ri. When the same foams flow through either open or packed Pyrex tubes, remarkably high streaming potentials ?E are often generated. These can easily reach 50v if nonionic foaming agents are used, but are at least an order of magnitude less for ionic foaming agents. A linear relationship between ?E and the pressure differential ?p is observed; this usually extrapolates to positive values of ?p at ?E of zero. The slope of the line increases with both F and ri. An equation was derived to describe the streaming potential of non- Newtonian fluids in circular tubes and was used to correlate experimental results. The calculated < potentials are of the right order of magnitude. INTRODUCTION Foams are both unusual and inniguing in their physical properties, and have been the subject of many scientific studies. However, present knowledge of foams is still fragmentary, specific and often contradictory. Apparent viscosity of foam is the physical property of greatest interest to both rheo1ogists and engineers. sibreel reported that the apparent viscosity decreased with increasing shear rate in a manner similar to some non-Newtonian fluids. Penny and Blackman2 reported that fire-fighting foams had both a limiting shear stress and a tensile yield stress. There is little doubt that some foams at least behave like non-Newtonian fluids, and have apparent viscosities considerably higher than those of either constituent phase. The high apparent viscosity of foam with its concomittant effect on mobility ratio and sweep efficiency no doubt prompted several attempts by research groups to use foam as a displacing agent in porous media. Based on recent experience, most of these groups probably succeeded in completely blocking fluid flow in the porous media and then abandoned their efforts. Two groups apparently found the successful combination of experimental parameters at about the same time.3,7 Others have recently added to our knowledge of foam flow in porous media and its use as a displacing agent.8-13 An experimental problem encountered by Fried3 was a transient blockage of foam flow in porous media when distilled water was used to prepare the foam-producing solution. Fried surmised that this was due to an electrokinetic effect and he eliminated it by using electrolytes in preparing foaming solutions. He also measured the streaming potential of a number of foams in capillary tubes which he found to be appreciably higher than those obtained when the constituent liquid flowed under comparable conditions. This paper presents results of a more comprehensive study of the streaming potential generated by aqueous foam flowing in both open and packed Pyrex tubes. It also adds to knowledge of the rheology of these foams as deduced from their flow behavior in open tubes. APPARATUS AND PROCEDURE A diagram of the apparatus used is shown in Fig. 1. Details of its construction, testing and use are described elsewhere.14 Careful selection of materials, extreme cleanliness and rather elaborate electrical insulation and shielding were necessary to obtain reproducible results (±5 percent). Both streaming potential and streaming current were measured with an electrometer. The design of the foam generator developed for this work is novel (Fig. 2). It will produce uniform fine-textured foams at pressures sufficiently

"Located in Madison River Canyon, about 14 miles by road from Norris, Mont. Built in 1907 by Madison River Power Co.DAM: Rock filled wooden crib structure, 183 ft. long, 34 ft. high or 44 ft. to top of flashboards.SPILLWAY: 140 ft. long, equipped with flashboards 10 ft. high.PIPE: One 10-foot and one 12-foot wood-stave pipe, 7,515 feet long.PRESSURE: One pressure chamber, 32 ft. high, 30 ft. wide and 81 ft.CHAMBER: long, built of concrete.PENSTOCKS: 4 9-foot steel penstocks about 200 ft. long, one for each wheel.WATER WHEELS: 4 double horizontal, center discharge, Sampson special 44-inch turbines, 3,600 h-p., at 100 ft. head. Speed 300 r. p. m„ direct connected to generators.GENERATORS: 4 G. E., W. C., 2,250 k-w., 4,000 volts, 300 r. p. m., 3 phase, 60 cycles, alternators, with exciters mounted on same shaft.TRANSFORMERS: 12 G. E., W. C., 900 k-w., 60 cycles. High tension voltage 23,100, 34,650, 46,200; low tension voltage 4,000, 3,800, 3,600. Now operating at 46,200, delta connected. They can be connected Y for 40,000, 60,000 or 80,000.OPERATION: This is the principal plant of the whole system and carries most of the load."

Jan 1, 1913

By Gilbert P. Moore

Production in the Argentine in 1930 amounted to 1,415,099.7 metric tons, which converted into barrels of 42 gal., using the factor of 6.29, amounts to 8,909,773 bbl. This is a decrease of 481,613 bbl. from the 1929 production, which was 9,391,386 bbl. The production for 1930 was divided among three fields, as shown in Table 1. Table 2 covers Table 1.—Argentine Oil Production, 1930, by Fields Barrels Comodoro Rivadauia District Government........................................... 4,547,670 Railways Co........................................... 1,314,358 Astra-Eastern......................................... 1,016,024 Anglo-Persian......................................... 365,021 Solano Co............................................. 24,613 Dutch Shell........................................... 6,963 7,274,649 Neuquen District Government........................................... 569,245 Standard Oil-Argentina................................. 659,551 Astra-Eastern......................................... 8,234 Challaco Co. (Sol)...................................... 121,598 1,358,628 Salta District Government........................................... 90,576 Standard Oil-Argentina.................................. 185,920 276,496 8,909,773

Jan 1, 1931

By Ralph Hultgren, Bernard York, David W. Mitchell

It is a well-known fact that magnesium-alloy castings are apt to be coarse grained if the melt is not superheated several hundred degrees above the melting point before casting. (The casting temperature varies according to the shape of the mold. A typical casting temperature is perhaps 1400°F.) British practice is to heat to 900°C. (1650°F.) for 15 min., cool rapidly to casting temperature, and cast.&apos; In Germany superheating is carried out at 850&apos; to 900°C. (1560° to I650°F.) depending on the amount of scrap used. It is stated that further refinement will be obtained by prolonging the period of superheating or by increasing the superheat temperature to 950°C. (I740°F.).2 In the United States superheating is carried out at 1600&apos; to 1700°F. (871&apos; to 927°C.), perhaps even higher in some places. It is stated that superheating effects are found as low as 1500°F. (816°C.), but several hours are required.3 These commercial treatments lead to grain sizes in sand castings that may vary from 4 to 8 grains per sq. mm.! in heavy sections and from 60 to IOO in 1/2-in. sections to perhaps 380 in thin sections. It is also generally known that the refining effect of superheating is lost if the melt is held for some time at lower temperatures before casting. Aside from these very qualitative statements, there is little to be found in the literature as to the effect of temperature and time of superheat on the final grain size. Because of the uncertainty of these factors, the Office of Production Research and Development of the War Production Board placed a research contract with the University of California, supervised by the War Metallurgy Committee. This research, which was done under the "Restricted" Project NRC-550, is the basis of this paper, which has been released for publication by the O.P.R.D. The material studied was an alloy prepared from carbothermic magnesium. The temperatures required for grain refinement proved to be widely different from those used in practice, as described in the statements in the first paragraph. This difference is attributed to the fact that the magnesium in the specimens was of carbothermic origin instead of the electrolytic magnesium in common use. Materials and Methods The magnesium alloy studied was one of the most popular sand-casting alloys, with a nominal composition of 9 Per cent aluminum, 2 per cent zinc, and 0.1 per cent (minimum) manganese and the balance magnesium. This is designated

Jan 1, 1945

By T. PH. D. Egleston

THE origin of gold both in placer deposits and in veins, and especially the origin of nuggets, has been the subject of repeated discussions and investigations, which have been recently brought to my attention by several extremely interesting specimens sent to me for examination, and more especially by the one exhibited at the meeting of the Institute in February, 1880.* In the year 1874 I made some examinations of the hydraulic mines of Califor¬nia, and was very much struck with the distribution of the gold throughout these deep placers, which were almost invariably poor on&apos; the surface, while gradually growing richer towards" the bed¬rock. The constant presence of fossil wood, and the large quantity of organic matter contained even low down in these beds, was also remarkable. Not being satisfied with the various theories advanced to account for the formation of these deposits, I began an investiga¬tion early in the year 1879 on the conditions of solubility of gold and the causes of the loss in working gold ore in a large way: The researches which I have undertaken show that gold must be considered a soluble rather than an insoluble metal, and that the conditions of solution are such as will be found anywhere where gold is likely to occur, and the solution may take place even under the ordinary cir¬cumstances of surface drainage, and may be going on freely even where the presence of gold has never been suspected, and that there are causes enough in nature to produce the solution of the gold in sufficient quantities to account for all the phenomena of both the vein and placer formations. The general theory with regard to the formation of these placer deposits and nuggets has been that they were the result of the de¬struction of pre-existing- vein-matter, which does not accord with the facts as shown in the deep placer deposits. The gold in such case would be distributed in layers of unequal richness throughout * Transactions of the American Institute of Mining Engineers, vol. 8, p. 451.

Jan 1, 1881

By J. Kucera, J. Vreštál

DIFFERENT authors1 &apos; have been engaged in meas-uring the vapor pressure of pure cobalt. The results of their measurements satisfy the expected temperature dependence of vapor pressure and are in mutual agreement, with the exception of the results by De Dyk Man and ~esmejanov.~ The latter authors, by using the effusion method, have achieved considerably higher values than other workers. By using the isotope exchange method they obtained much lower values than other authors. The determination of thermodynamic functions of the binary Ni-Co system was carried out, as far as we know, only by De Dyk Man and Nesmejanov.4 This determination was based on extremely low values of vapor pressure over pure cobalt obtained by the isotope exchange method. Therefore we considered it useful to repeat these measurements. Furthermore, the reliable values of thermodynamic functions should complement the migration characteristics, the inner magnetic field data obtained by Miissbauer effect measurements, specific heat data, and the K effect and positron annihilation characteristics that have been achieved for the Ni-Co system in the Institute of Metallurgy of the Czechoslovak Academy of Sciences in Brno.5-9 The measurements in this paper were performed by the isotope exchange method. In this method, as has been shown by analysis,10-&apos;3 the vaporization rate, w, can be calculated from the relation w = k/1oSw [1] i0Sw) [1] where L, is the activity per unit mass of the source, S is the area of evaporation, k is the tangent at the point t = 0 to the curve giving the radioactivity de-pendence of the target vs annealing time, t, and wis the probability for the tracer atom condensation on the target surface. The value for cc. can be obtained from the equation w = a + 2P(l-a) [2] where P is Clausing&apos;s coefficient and a is the condensation coefficient. In the present work the cylinder shaped containers for annealing the samples were used, characterized by the ratio 1:d = 1.06. Here 1 is the length and d the diameter of the container. For this ratio P = 0.514 and w =0.5, and w is independent of the condensation coefficient. The vaporization rate is related to the vapor pressure p by the relation where R is the gas constant, T is the absolute temperature, and M is the molecular weight of the component investigated. Measurements of the vapor pressure of the i component over the pure metal, p!, and the alloy, pi, at the given temperature and composition enable one to calculate the thermodynamic activity of this component from the equation ai=pi/pi [4] is and the activity coefficient ri=ai/xi [5] xi where xi is the molar fraction of the investigated alloy component. EXPERIMENTAL Evaporization rate measurements were carried out with pure cobalt and eight different Ni-Co alloys, which were kindly delivered by the Centre National de Recherches Me&apos;tallurgiques Liege, Belgium. The composition of the alloys is given in Table I. The cobalt used in these alloys contained the following impurities: 0.016 wt pct Fe, 0.014 wt pct Cu, 0.01 wt pct Mn. Other elements were present in much lower concentrations. From the melts, samples in the form of small cylinders of 12 mm in diam were ma-chined. The thickness of the targets and sources was 2.5 and 1.2 mm, respectively. The lower thickness of the sources was chosen to make their over-all ac-tivity as low as possible. Sources were activated in

Jan 1, 1970