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By H. J. Struth

AN unusual engineering achievement in the Gulf Coast last year was the drilling of a wildcat well in the swamps of Louisiana, using direct current. More unusual was the fact that it was necessary to house a diesel engine and generator on a barge in order to supply power. The remoteness of the well made it necessary to transport living quarters and drilling equipment to the location by means of barges, and involved the digging of a canal from a lake to the location, approximated one mile. The drilling equipment used on this well consisted of two generating units, each having one 210-hp. six-cylinder @$-in. bore type VDMA, 600 r.p.m. diesel engine, direct connected to a type CD-169, 125-kw., 250-volt direct current generator, which in turn is direct connected to a type CD-105, 15-kw. 250-volt exciter. One of these motors operates the draw works, one the mud pump, and one a duplicate spare. The generating equipment on the barge was approximately 250 ft. from the derrick, the control wires being brought from the derrick to the generator barge enclosed in a standard fire hose. This is an original idea for confining the con- 11.01 wires in one cable; obtaining minimum space and ample protection. Both control and power lines were suspended on poles. This well was at Lake Grande Ecaille Dome, which was located by seismograph in 1928. Fig. 1 shows the derrick, power barge and living quarters where direct G. E. current was used with rotary drilling equipment.

Jan 1, 1932

By Philip D. Wilson

OF all the metals in the war program the demand for and the production of magnesium have increased percentagewise the most. In the prewar year 1939 the production was 3350 tons. The war program, twice expanded, now provides for nearly one hundred times that amount annually. The goal announced by the War Production Board in February 1942 was 362,500 tons per year. Be- cause of the development during the year of satisfactory types of incendiary bombs other than magnesium this objective has been somewhat reduced but the capacity of the plants already built or under construction will be huge. The Aluminum and Magnesium Division of the W.P.B. has had the responsibility of planning and implementing this expansion and of providing fabricating facilities as well for this greatly increased tonnage of magnesium ingot.

Jan 1, 1943

By J. H. Frye, J. L. Scott, J. W. Woods

THERE are at least two effects of temperature on the stress required to produce plastic flow. 1) Metals plastically strained for the same amount at different temperatures possess different stress-strain curves and different internal structures (e.g., nature and density of imperfections). 2) There is both experimental and theoretical evidence that the stress necessary to produce plastic flow may vary with temperature even though the internal structure remains constant.1-5 Much of the data in the literature is difficult to interpret because these two effects are simultaneously present. In the work reported here, they are considered separately. Standard 0.505 in. tensile specimens were prepared from high-purity Mond nickel and OFHC copper. Nickel specimens were annealed in hydrogen at 1150°C for 30 min and furnace cooled. This produced an average grain diameter of 1.4 mm. Copper specimens were annealed in vacuum at 525°C for 6 hr and furnace cooled. This produced an average grain diameter of 0.11 mm. Nickel tensile specimens were prestrained in tension at 500°K, whereas copper tensile specimens were prestrained in tension at room temperature. All specimens were cooled to 74°K and heated to room temperature. After these treatments all of the tensile specimens of a given set possessed identical structures. All specimens were returned to the tensile machine and tested at various temperatures and constant cross-head speed. Many of the tensile curves showed well defined yields but, in order to minimize personal judgment, the yield was always chosen as the stress corresponding to 0.2 pct plastic deformation. Results are summarized in the graph of yield vs temperature of test, Fig. 1. All of the specimens corresponding to any one line have had identical treatments and, therefore, have identical internal structures. Thus, each line gives the relation between yield stress and temperature for one constant internal structure. The lowest line, which is for annealed nickel, shows no measurable variation of yield with temperature. This is similar to Blewitt's6 results on copper single crystals, but a variation in yield with temperature was found by Andrade and Henderson' in single crystals of nickel, and by Car-recker and Hibbard8 in annealed polycrystalline copper. The three other lines, which are for prestrained materials, show that there is a linear relation between yield stress and temperature when the internal structure remains constant. Such a relation might be expected from a rate equation such as that of Kauzmannl on the assump- tion that the activation energy is either independent of or linear with temperature. These results would also be expected if the shear moduli of copper and nickel are linear functions of temperature for, as Cottrell and Stokes have pointed out," in all dislocation theories of strength the flow stress appears proportional to the shear modulus of the material. In copper and nickel, since the modulus of elasticity decreases roughly linearly with increase in temperature," it is probable that the modulus of shear also decreases approximately linearly with increasing temperature. A detailed discussion of the effect of these and other factors on the temperature dependence of flow stress in face-centered-cubic metals has recently been given by Seeger.4

Jan 1, 1958

By T. M. Girdler

INDUSTRIAL progress and development in this country from the earliest daps to the present has proceeded at an ever-quickening pace. Yet during recent decades the nature of our industrial progress and development has undergone a change of great significance. The earlier days were a period of tremendous expansion. Population was increasing by leaps and bounds. Vast areas of new land were being .2 opened to settlement. And almost boundless new sources of timber, coal, oil, ores, and power were being opened to ever-expanding markets. Today, however, that picture has al- most completely changed. Today, with population increase tapered way off and the opportunity for free expansion into western frontiers gone, the great industrial development of our country continues on a vastly different front. Industrial progress and development today rest on a foundation of technology. The key- stone is research. Our frontiers to- day are frontiers of sciencec

Jan 1, 1939

By M. W. BERNEWITZ

DURING my recent extended visit to Australia and New Zealand, these notes on oil and gas prospecting in that part of the world were compiled from recent reports-press and government, from conversation with one of the financial leaders in the search for oil, and from personal observation of operations of the principal importers, blenders, and distributors of oil products; also from the astonishing testimony given by them to the Petrol Commission. Australia and New Zealand have practically no petroleum production beyond a few thousand gallons a year from wells in the latter Dominion. Everything is imported, Table 1. showing the quantities for 1929-30 in Australia and for 1930 in New Zealand,

Jan 1, 1934

Organization Place Date 1919 American Railway Engineering Association Chicago, 111. Mar. 18-20 Society of Industrial Engineers New York, N. Y. Mar. 18-21 American Electrochemical Society New York, N. Y. Apr. 3-5 National Foreign Trade Council Chicago, Ill. Apr. 24-26 American Iron and Steel Institute New York, N. Y. May American Institute of Electrical Engineers Lake Placid, N. Y. June

Jan 3, 1919

By K. L. Sutherland, J. Rogers

The relationships between collector and mineral, activator and mineral, and activator, collector and mineral will be considered herein. We propose to criticize current theories of flotation but we will not repeat the many pertinent arguments presented by Wark and Cox28 in 1937 in which the "chemical" or more strictly the "solubility" theory proposed by Taggart and co-workers22 is shown to be untenable. Recently Taggart, Arbiter and Kellogg24 have studied the long-chain aliphatic amines as collectors and have attempted to resuscitate the solubility theory for these particular collectors. Dean and Ambrose3 have felt that "we stumble over words" when we distinguish different mechanisms of adsorption. Our view is that nothing is more stultifying to the development of a science than attempts to force widely different phenomena into one classification. This oversimplification leads immediately to difficulties in the interpretation of results. Experimental Procedure The response of minerals to activator and collector was determined by "captive-bubble" tests. The methods of preparation of specimens26 and of testingin have been previously described. Results from captive-bubble tests were confirmed by flotation tests in glass-stoppered cylinders.26 The full lines shown in the figures relating solution composition to contact (flotation) distinguish solutions in which contact (flotation) is possible from those in which it is not. The curve is derived by successive approximation and the accuracy is ±o.2 pH units and ±5 mg. per liter of collector or depressant. Solution compositions for which it was shown experimentally that contact or flotation is possible are marked by a circle, those for which it is not possible by a cross and those for which it is doubtful by a cross within a circle. It is assumed that at all other solution compositions within (without) the curve, contact or flotation is possible (not possible). After testing in the collector solution, the mineral was removed, washed, and tested by the captive-bubble method in water, or floated in a cylinder with frother only. In this way the composition of solutions in which a mineral was conditioned but in which properties of the collector solution prevented contact or flotation can be defined. The composition of solutions in which conditioning was possible lie between the full and broken curve, the experimental results being indicated on the figures by a square. The curves show the limits of composition of solution in which flotation in a cell would be possible. Many factors other than those considered in these tests determine recovery or grade of a given mineral in practice.

Jan 1, 1947

By J. Rogers, K. L. Sutherland

The relationships between collector and mineral, activator and mineral, and activator, collector and mineral will be considered herein. We propose to criticize current theories of flotation but we will not repeat the many pertinent arguments presented by Wark and Cox28 in 1937 in which the "chemical" or more strictly the "solubility" theory proposed by Taggart and co-workers22 is shown to be untenable. Recently Taggart, Arbiter and Kellogg24 have studied the long-chain aliphatic amines as collectors and have attempted to resuscitate the solubility theory for these particular collectors. Dean and Ambrose3 have felt that "we stumble over words" when we distinguish different mechanisms of adsorption. Our view is that nothing is more stultifying to the development of a science than attempts to force widely different phenomena into one classification. This oversimplification leads immediately to difficulties in the interpretation of results. Experimental Procedure The response of minerals to activator and collector was determined by "captive-bubble" tests. The methods of preparation of specimens26 and of testingin have been previously described. Results from captive-bubble tests were confirmed by flotation tests in glass-stoppered cylinders.26 The full lines shown in the figures relating solution composition to contact (flotation) distinguish solutions in which contact (flotation) is possible from those in which it is not. The curve is derived by successive approximation and the accuracy is ±o.2 pH units and ±5 mg. per liter of collector or depressant. Solution compositions for which it was shown experimentally that contact or flotation is possible are marked by a circle, those for which it is not possible by a cross and those for which it is doubtful by a cross within a circle. It is assumed that at all other solution compositions within (without) the curve, contact or flotation is possible (not possible). After testing in the collector solution, the mineral was removed, washed, and tested by the captive-bubble method in water, or floated in a cylinder with frother only. In this way the composition of solutions in which a mineral was conditioned but in which properties of the collector solution prevented contact or flotation can be defined. The composition of solutions in which conditioning was possible lie between the full and broken curve, the experimental results being indicated on the figures by a square. The curves show the limits of composition of solution in which flotation in a cell would be possible. Many factors other than those considered in these tests determine recovery or grade of a given mineral in practice.

Jan 1, 1947

By B. M. Larsen, K. Heindlhofer

THIS paper describes a relatively simple electrical apparatus that, through the close analogy between the flow of heat and of electricity, enables one to solve quickly and with satisfactory accuracy many complex problems in heat flow. This device, developed in 1935, has proved especially useful in the solution of certain practical problems relating to the design and efficiency of regenerators for an open-hearth furnace or coke oven, yielding within a few hours information that would take weeks or even months to acquire by mathematical1.2 or experimental3 methods of comparable accuracy. Its description now is prompted by growing interest in such analogues, as shown by several recent papers.4.5 The analogy between flow of heat and of electricity appears to have been recognized first by Maxwell who, in his famous Treatise on Electricity and Magnetism (1881) says: The analogy between the theory of the conduction of electricity and that of the conduction of heat is at first sight almost complete. If we can take two systems geometrically similar, and such that the conductivity. for heat at any part of the first is proportional to the conductivity for electricity at-the corresponding part of the second, and if we also make the temperature of any part of the first proportional to the electric potential at the corresponding point of the second, then the flow of heat across any area of the first will be proportional to the flow of electricity across the corresponding area of the second. .. Thus, in the illustration we have given, in which flow of electricity corresponds to flow of heat, the electric potential to temperature, electricity tends to flow from places of high to places of low potential, exactly as heat tends to flow from places of high to places of low. temperature He noted, however, that this analogy is restricted: ... there is, however, one remarkable difference between the phenomena of electricity and those of heat. Suspend a conducting body within a closed conducting vessel by a silk thread, and charge the vessel with electricity. The potential of the vessel and of all within it will be instantly raised, but however long and however powerfully the vessel be electrified, and whether the body within be allowed to come in contact with the vessel, or not, no signs of electrification will appear within the vessel, nor will the body within show any electrical effect when taken out. But if the vessel is raised to a high temperature, the body within will rise to the same temperature, but only after a considerable time, and if it is then taken out it will be found hot, and will remain so till it has continued to emit heat for some time. The difference between the phenomena consists in the fact that bodies are capable of absorbing and emitting heat, whereas they have no corresponding property with respect to electricity. According to this statement the application of the analogy would be limited to problems of steady flow that do not involve heat-capacity effects. In spite of this

Jan 1, 1945

By D. E. Thomas, C. E. Birchenall

ALTHOUGH Eoltzmann gave a mathematical solution for the diffusion equation (for planar diffusion in infinite 01. semi-infinite systems only) in 1894 allowing for variation of the diffusion coefficient with a change in concentration, it was not until 1933 that this solution was applied to an experimentally investigated metallic system. The calculation was carried out by Matano' on the data obtained by Grube and Jedele3 for the Cu-Ni system. Since that time concentration dependence of the diffusion coefficient has been demonstrated for many pairs of metals. However, the nature of this dependence has never been fully elucidated. Many investigators have suspected that these variations could be related to the thermodynamic properties of the solutions, one of the earliest explicit statements being contained in a discussion of irreversible transport processes by Onsager' in 1931. Development along these lines has been greatly retarded by the lack of reliable data on the variation of tliffusivity with concentration, the paucity of the thermodynamic data for the same systems at the same temperatures and compositions, and an incomplete understanding of the relation of the thermodynamic properties of the activated state for diffusion to the bulk thermodynamic properties. The last factor has been discussed by Fisher, Hollomon, and Turnbull.5 In many instances where data exist, it is difficult to know which are acceptable. This problem probably applies more strongly to diffusion data than to activity measurements. For instance, four sets of observers"-" have reported self-diffusion coefficients for copper. The average spread between extreme results is a factor of about four, though the individual sets of data are self-consistent to about 20 pct. Thus one or more factors are out of control, at least in these experiments, making estimates of internal error unreliable. The most reliable diffusion data in most systems have resulted from the use of welded couples with a plane interface from which layers for analysis are machined parallel to the interface after diffusion. The layers are analyzed, and the result is a graphical relation between distance and concentration, usually called the penetration curve. Given the same set of analytical data and distances and following the same procedure in computation, different observers will generally produce diffusion coefficients which vary appreciably, especially at the extremes of the concentration range. Experiments must be carefully designed so that the precision is good enough to answer a particular question unequivocally. In the first calculation of the dependence of the diffusion coefficient on concentration in the metallic solid solution Cu-Ni, Matano found that the coefficient was insensitive to concentration from 0 to 70 pct Cu, after which it rose more and more steeply to some undetermined value as pure copper was approached.' The same behavior was reported for Au-Ni, Au-Pd, and Au-Pt.* The data used were those of Grube and Jedele which were very good at the time, but are not considered particularly good by present standards. Furthermore, the method of calculation makes the ends of the diffusion coefficient-concentration curve unreliable. For better reliability, the high copper end of the curve has been checked by incremental couples, where the concentration spread is 67.7 to 100 atomic pct Cu. The implication of the curves calculated by Matano was that diffusion is very concentration sensitive in one dilute range of this completely isomorphous system and hardly at all in the other. Matano's result is confirmed. Later Wells and Mehll0 published data on diffusion in Fe-Ni at 1300°C, which represent a thorough test of the shape of the concentration dependence curve. They ran couples with the following ranges of nickel concentration: 0-25 pct, 1.9-20.1 pct, 0-20.1 pct, 20.1-41.8 pct, 0-99.4 pct, and 79.3-99.4 pct. Although the trend of the data indicates an S-shaped concentration dependence, their curve was drawn to the pattern set by Matano. Their original data have been recalculated for the 0-99.4 and 79.3-99.4 pct couples. Wells and Mehl's points and two independent recalculations from the raw data are plotted in Fig. 1. What appears to be the best curve is drawn through them. This curve shows little sensitivity to composition in both dilute ranges with a strong dependence at intermediate composi-tions.? Similar experiments on the Cu-Pd system are reported here at temperatures where solubility is unlimited. These lead to the same type of concentration dependence for the diffusion coefficients as was found upon recalculation of the data for the Fe-Ni system. Experimental Procedure Cu-Pd: The concentration dependence of the diffusion coefficient may be determined by the use of

Jan 1, 1953

By D. T. Peterson, F. A. Schmidt, J. D. Verhoeven

The velocity of mig-ration of these solutes in thorium metal due to a high amperage dc current was measured at several temperatures. All three solutes migrated in the same direction as the electron flow. Diffusion coefficients were combined with the migration velocities to predict the steady-state concentration profile. Electrotransport was shown to be an effective method of removing carbon, oxygen, and nitrogen from thorium and resistance ratios several times larger than for crystal bar thorium were achieved. However, the maxirnum attained purification was well below the predicted values, apparently due to some form of contamination. THE migration of solutes in metals when a high current density dc current is passed has been known for many years. This phenomenon has been the subject of a number of reviews published in recent years.l~* Many of the earlier investigators of electromigration of interstitial solutes interpreted the direction and velocity of migration on the basis of a charge on the solute particle. This interpretation is unclear because, in a given experiment, one cannot separate the contributions to the force moving the solute which arise from the charge on the solute in an electric field gradient and the momentum transfer from the scattering of the electrons or holes. There have been only a few quantitative measurements of interstitial migration velocities and some of these have been characterized by poor accuracy or by errors in the analysis of the experiment. The electrotransport mobilities of carbon, nitrogen, and oxygen in thorium were determined by observing the rate of movement of a discontinuity in the concentration profile. This method was used by Carlson el a~.~ to determine the mobilities of interstitial solutes in yttrium and its advantages are discussed in that paper. The specimen is essentially a pair of semi-infinite, bar-type diffusion couples. The electro-transport velocity was measured by observing the displacement of the mean concentration point in a measured length of time. The diffusion coefficients were calculated by the Grube method from the concentration profile. The transport mobilities and diffusion coefficients can be used to predict the concentration profile in an electrotransport experiment of a given time, current density, and specimen length. At long times a steady state will be reached such that the natural logarithm of the concentration of each solute varies linearly along the bar with a slope which is equal to the velocity of the migrating solute divided by its diffusion coefficient. The estimation of the purification potential of electrotransport is discussed by ~erhoeven.' A comparison of the concentration profile and the purification which should be expected from known solute velocities and diffusion coefficients with that which is obtained in an experiment can be very useful in indicating whether the maximum possible purification has been achieved. EXPERIMENTAL METHOD The apparatus used in this study consisted of a sample chamber which was equipped with two electrodes, a sight glass, and a flange for mounting to a high-vacuum system capable of obtaining pressure of 2 x lo-? Torr. The chamber was made of stainless steel and was 4 in. in diam and 6 in. long. The seal between the electrodes and the chamber was made with "0" rings and compression bushings. The thorium specimens were threaded and screwed into tantalum "U"-shaped adapters attached to the ends of the electrodes. This arrangement is shown in Fig. 1

Jan 1, 1967

By J. B. Morrow, D. H. Davis

THERE are two general approaches to the problem of increasing profits from an operation. One is to lower expense; the other is to raise income. Mechanical preparation of coal may be used for either purpose but a prudent consideration of many details must precede any decision lest the results be negative instead of positive. It is quite possible that any net gain will result from a combination of the two. Since mechanically prepared coal invariably is a better product qualitatively than a hand-picked coal from the same mine, it is a reason¬able expectation that the customer will be willing to increase the pro¬ducer's income by paying a higher price. Or there may be the possibility that a combination of mechanical mining plus mechanical cleaning will give a lower over-all production cost for the coal in the railroad car. More likely, there will be found a combination of these two factors. From the customer's point of view, the competitive delivered cost per B.t.u. considered in relation to such incidental factors as dust nuisance, handling properties, ash disposal, and ash fusibility determines what he will pay. In a bulk tonnage product such as coal, freight is a very considerable part of the delivered fuel cost, and obviously freight paid on incombustible ash has no economic attractions.

Jan 1, 1943

By T. R. Schermerhorn, Samuel L. Hoyt

The hardness of annealed copper has been given in the literature and is easily obtained by any of the standard methods of hardness testing. It is not our intention to correct published values or to add to them, but to describe tests of two bars of annealed electrolytic copper in which the methods of Meyer's analysis were employed. Meyer's Analysis of Ball Indentation Test The ball indentation test is probably the most valuable hardness test we now have but, as it is carried out in the Brinell or Rockwell test, the result may be seriously in error without the operator suspecting such to be the case. This condition results from the isolated and uncontrolled nature of the measurement. The accuracy depends on the accuracy of the equipment and the care and skill used in the operations; there is nothing in the impression diameter, which is all that is measured, to indicate the presence of error. Meyer's analysis supplies a control of the measurements that goes far toward eliminating unsuspected errors. The principles of this work may be obtained from elsewhere.' As this subject has not received the attention of this Institute, it may be well to summarize the more important points as follows. The chief difference between the usual ball indentation hardness test and Meyer's test is the use of a number of loads, instead of one, covering the range from small to large loads. The reason for this may not be obvious; the resistance to penetration may, and generally does, vary with the penetration of the ball; consequently a single determination can give only the resistance at that particular load. At some other load, the resistance may be quite different. For example, a test on annealed copper at 250 kg. gave a resistance to penetration of 39.5 kg. per sq. mm., while a similar test at 3000 kg. gave a resistance of 56.8 kg. per sq. mm. For the purpose of finding some figure that might be used to represent the hardness of the sample of copper, there is no reason for selecting one of

Jan 1, 1926

By A. Becker, J. A. Slankis

Equipment has been developed to utilize natural 8 Hz electromagnetic fields to measure rock resistivities. Telluric and magnetotelluric surveys have detected resistivity variations associated with geological contacts and metallic sulfide deposits. The fundamenfa1 premises of these methods are illustrated by the results of surveys across a Pleistocene-Precambrian contact in the Ottawa Valley and a near-surface sulfide deposit in Northern Quebec. Such interfaces are characterized not only by variations in apparent resistivity, but also, unexpectedly by the spatial anisotropy of the electric fields and the presence of a strong vertical magnetic field component in their vicinity. Standard geophysical electrical and electromagnetic methods (Heiland, 1940) for the determination of the electrical properties of the ground and the search of good electrical conductors necessitate the use of a transmitter and receiver which are coupled galvanically or inductively through the ground. The electrical properties of the ground are deduced from either the transfer function, or the impulse response, of the transmitter — ground — receiver system. Where deep penetration is desired these methods require powerful transmitters whose weight and size increase the cost and reduce the speed of operation. It is possible however, to resort to another class of electrical prospecting methods which employ ambient, natural electromagnetic fields in place of a transmitter.'-' In the audio and subaudio frequency ranges, these fields are generated by thunderstorm activity. At some distance from the seat of the disturbance, the e.m. fields propagate as plane waves with a horizontal magnetic field component. The incident wave, of course, induces currents in the ground. Where the ground is homogeneous the relation between the horizontal magnetic and horizontal electric fields vectors is particularly simple:' /E/ = \[SpT/H/ (1) where: /E/ = magnitude of horizontal electric field in millivolts/kilometer (RMS) /H/ = magnitude of the orthogonal inducing magnetic field in milligammas (RMS) p = rock resistivity in ohm-meters i = frequency of measurement in c/s In practice, the ground is seldom an homogeneous half space, lateral conductivity variations exist, (in the case of base metal prospecting these are the features actually sought) and the two field vectors are no longer simply related. The ratio of E to H is still useful, however, for the determination of an "apparent" ground resistivity. From a theoretical view point, the general problem of a two dimensional fault or dyke anomaly can be separated into two distinct cases. In the first case, where the e.m. energy propagates in a direction normal to the strike, the horizontal magnetic field remains constant and is oriented along the strike of the formation.3 As shown by d'Erceville and Kunetz," all the information about the anomaly is contained in measurements of the electric field component. In fact, away from the interface, the electric fields are proportional to the square roots of the resistivities:

Jan 1, 1970

By Frederic Brunton

I. INTRODUCTION THE smelting plant of the British Columbia Copper Co. at Greenwood, B. C., now closed because of the decline in the price of copper due to the European war, is of special interest to metallurgists for several reasons. It was successfully smelting in blast furnaces the lowest grade copper ore of all plants in America. In order to do so, it had to run at' very high efficiency, which necessarily required a large tonnage per square foot of hearth area, together with the minimum amount of labor and other costs. The furnaces smelted daily 2,250 tons of ore (6.62 tons per sq. ft. of hearth area), carrying 0.85 per cent. of copper, at a smelting cost of $1.18 per ton. The entire plant required 130 men to operate it and keep up repairs, showing a labor efficiency of about 17.5 tons per man per day. In the present paper, the method of obtaining these results is shown. Most of the information contained in this description I obtained as Assistant Superintendent, during the two years preceding the present shutdown. Other sources of information to which I am indebted are: The British Columbia Copper Co., Ltd., by Alfred W. G. Wilson, in The Copper Smelting Industry of Canada; Greenwood Smelting Works, by J. E. McAllister, Engineering and Mining Journal, vol. xci, pp. 1011 to 1015 (May 20, 1911); and Description of the Copper Smelter of The British Columbia Copper Co., by W. L. Bell, in Transactions of the Canadian Mining Institute, vol. xvi, pp. 151 to 154 (1913).

Jan 7, 1915

By Robert E. Green, Edmund G. Henneke

Expressions are derived for the orientation factors associated with dislocation damping due to dislocation motion in the basal slip plane. The results of the calculation of these factors for zinc crystals aye pvesepzted and the relevance of these results to ultvasonic-attenuation measuvements is discussed. In this paper expressions are derived for the orientation factors associated with damping of sound waves due to dislocation motion in the basal slip plane of hexagonal crystals. For zinc crystals, the orientation factors for dislocation motion in one slip direction only, as well as for simultaneous motion in all three basal slip directions, have been calculated at 1-deg intervals. The results of these calculations are presented in the form of contour diagrams in a sector of a standard polar coordinate graph. The calculations have been carried out for both the traveling- and the standing-wave conditions. The relevance of these results to ultra sonic-attenuation measurements is discussed. Associated with the calculation of the orientation factors, the modes of elastic-wave calculation were also evaluated, according to the procedure previously employed by Hinton and Green.' The results of these calculations are not presented here since similar results have been reported earlier by Mus-grave.2 However, it should be mentioned that, although the qualitative features of Musgrave's results are preserved, the quantitative values are somewhat altered since different values for the elastic constants of zinc were used. ORIENTATION FACTORS It is convenient to refer to three different sets of coordinate axes, Fig. 1, in the following calculations. First, there are the Miller-Bravais axes which are used in describing the Miller-Bravais indices of planes and directions in a hexagonal crystal. These axes are denoted in the conventional manner by a,, a,, a,, and c. The second set of axes used is a rectangular Cartesian coordinate system located as shown in Fig. 1. Note that the x axis coincides with the close-packed direction al [2110], the z axis coincides with the c axis [0001], and the y axis is orthogonal to these two lying in the [0110 ] direction. Finally, a form of Eulerian angles is used to locate the position of the specimen axis. The angle between the specimen axis and the c axis is denoted by 0 and the angle between the projection of the specimen axis on the basal plane and the a, direction is denoted by ø. The majority of observations on plastic deformation of metal crystals indicates that such deformation is caused by the motion of dislocations on a limited number of crystalline planes and in a close-packed direction. In crystals with hexagonal symmetry the most prominent slip plane is the basal plane (0001) and the slip directiops- are one of the close-packed directions, [2110], [ 12101, or [ 1120]. To properly set the stage for the following work, several points must be clarified. First, we want to consider the contribution to the attenuation of elastic waves by dislocations only. While the Granato-Lucke, model for dislocation damping is presently the one most quoted, it is not necessary to refer the present work to it. The only assumption that need be made is that the motion of dislocations absorbs energy from the elastic wave and therefore attenuates it. It is immaterial here how this energy absorption occurs. However, because dislocations have been observed to move most freely on the (0001) plane for hexagonal crystals undergoing plastic deformation, it will be assumed that it is the dislocation motion on this plane which attributes to the observed attenuation. The basic orientation factor, Ok, is essentially the same as that used by Green and Hinton for fee crystals,4 defined by the equation

Jan 1, 1968

By A. C. Watts

For several years, a mine in Colorado experienced considerable trouble from small fires caused by the blasting of coal. Although a well-known make of permissible powder was used, it was first thought that the powder ignited gas that might be present and that this, in turn, set fire to line brattices or to the coal. Experiments were, therefore, conducted with another make of powder, but the results convinced the superintendent of the mine, Robt. Williams, Jr., that the fires were not caused by the powder but by the high-voltage electric current used for detonating the shots. The mine "makes" gas very freely, giving off from three-fourths to one million cubic feet of methane every 24 hours. The coal is a good grade bituminous of a very free burning quality. Electric shot-firing from the outside, after all men and animals were outside, had been practiced for a number of years. The shooting circuit was connected with the main power circuit at the mouth of each entry. Shooting circuit switches were mounted in boxes, which were kept locked with the handle of the switch, in open position, showing through the bottom of the box. The door of the box could not be shut and locked when the shooting switch was closed. At the entrance to each room, or working place, a small switch, called the miner's switch, was placed on the shooting line. It was the duty of the miner, when entering his place at the beginning of the shift, to see that this switch was open and that it was kept open until he left the placc at the end of the shift to go out of the mine. Grounded return was used for main power lines. The current was 500 volts, direct current, with 100 to 300 amp. The nearest working face was 9600 ft, from the shot-firers' switch outside the mine and the most remote working face was 2½ miles. The various working faces were scattered over a wide area between these two points. A description of the main power line would be valueless; the conductors were of sufficient size, the drop in voltage being not more than

Jan 1, 1927

By Sidney H. Haughton

WHEN the white pioneers of the eighteenth and nineteenth centuries advanced from the coastal settlements of southern Africa into the interior of the subcontinent, they found it inhabited, more or less sparsely, by brown or black peoples mainly of pastoral habits but equipped with a fighting spirit and certain fighting weapons. Some of the tribes were smiths, others were miners and metallurgists; all used fuel, either industrially or domestically. Some of that fuel was wood, some cattle dung, and in some places the natives mined outcrop coal. Coal was first discovered by Europeans in Natal about 1840. After proper deliberation and after allowing due time for a consideration of all the implications, the Natal Government decided in 1881 (40 years after) to import an English expert to investigate and report on the discovery. Things then moved rapidly, and in what to a geologist is the remarkably short space of eight years, Natal collieries were producing at the rate of nearly 30,000 long tons per annum or 100 long tons per working day!

Jan 1, 1945

By Robert H. Merrill

In 1960, the Kennecott Copper Corp. and the U.S. Bureau of Mines entered into a joint research program to determine the changes in stress, strain, and displacement created by changes in slope angles. The field site was the Kimbley Pit, located near Ely, Nev. The supporting laboratory investigations were made at the Bureau's Denver Mining Research Center. Following a study to determine the rock stresses in the mining district, the strike and dip of geologic defects (fractures) in the rock, and the laboratory-determined strength of the rock, a new slope angle and pit configuration was selected, and instruments were installed to measure changes in stress, strain, displacement, microseismic noise rate, and sonic velocities at several points in the west wall of the pit. Between February and November 1966, the west slope was changed from an average angle of 45' to a slope angle that started at 45° on the south wall, and gradually increased to 575' at the center of the west wall, and to 61° on the north wall. The pit was deepened from about 500 ft to about 550 ft. About 2.55 million tons of waste and ore were removed by stripping and mining. Measurements made between November 1965 and September 1967 showed that the pit wall was stable before excavation began, that changes in the measured quantities occurred in the pit wall during the excavation, and that the wall returned to a condition of equilibrium after the mining was completed. The need for a method and the technology to pre-design a pit slope does not require elaboration. About 5 billion tons of material are excavated yearly by surface mining methods in the United States, and the economics, safety, and availability of lower grade metals, nonmetals and fuels could all be substantially improved if operators could preselect optimum slope angles. Mining companies and the Bureau of Mines have recognized the need for developing engineering methods to determine stable slope angles. In the industry, Kennecott Copper Corp. had been making an

Jan 1, 1969

Question 1—1s Structural Deformation of Some Character Always Necessary for the Migration of Mineralizing Solutions. Especially in Limestone or Other Dense Rocks Discussion by: A. M. Bateman.........120 S. F. Kelly........... 125 C. H. Behre. Jr........118.123 G. B. Langford......... 123 T. M. Broderick.........121 H. E. McKinstry......... 116 R. H. Clarke.......... 123 D. H. McLaughlin........ 118 J. D. Forrester for M. H. Gidel . . 11.4 W. H. Newhouse......... 123 G. M. Fowler......112. 116. 121 R. H. Sales.......... 116 L. C. Graton..........121 Edward Sampson......... 122 R. D. Hoffman.........120 J. 8. Stevenson.......... 117 I. B. Joralemon.........121 L.B.Wright........... 112 Question 2—What Are Some of the Chemical and Physical Characteristics in Certain Beds within a Limestone Formation that Determine Their Favorable or Unfavorable Aspects as Reservoirs for Ore and Other Introduced Minerals? Drscussion by: G. W. Bain....... 127 G. M. Fowler....... 131 C. H. Behre, Jr. ..... 131 L. C. Graton....... 128 J. S. Brown. ...... 126 G.. F. Loughlin...... 128 E. L. Bruce ....... 129 R. H. Sales........ 129 R. H. Clarke...... 130 A. K. Snelgrove....... 130 Question 3—Are There Any Criteria by Which One Can Determine When Mining Operations Have Reached the Roots of an Ore Deposit? Discussion by: J. M. Boutwell...... 139 G. B. Langford..... 139 T. M. Broderick..... 138 . G. F. Loughlin...... 135 E. Y. Dougherty..... 137 R. H. Sales...... . 134 G. M. Fowler....... 132 F. A. Thomson..... 136 I. B. Joralcmon...... 132 Edward Wisser:..... 140 General s. F. Kelly................. . ...........145 References...............................146

Jan 1, 1941