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By F. J. Haller

IN 1943, we found, in the new Mather operation, a very unusual and disappointing condition in the footwall rock where all of our main haulageways were to be located. With the exception of a few hundred feet out of the thousands then planned and since driven, all of the openings require support. In general, the ground is not particularly heavy, at least by our standards, but it must be supported and the back carefully covered. Also, our operations require rather wide plat openings (16 to 18 ft) and rather flat curves at the turn-outs, all of which adds to the problem. When this completely unforeseen condition was discovered, ordinary timbering was the only answer, because of the impossibility of obtaining adequate steel supplies in time due to war shortages. Then by the time steel supplies were obtained and a practice developed, we found ourselves with between four and five miles of main haulage drifts and plat openings of a permanent nature, all of which were supported by hardwood timber, some of which had already rotted to an unsafe degree. Also, our drifting program was adding some two miles per year to the above figure. F. J. HALLER, Member AIME, is Superintendent, Mather Mine, Cleveland-Cliffs Iron Co., Ishpeming, Mich. AIME Columbus Meeting, September 1949. TP 2840 A. Discussion (2 copies) may be sent to Transactions AIME before May 31, 1950. Manuscript received Aug. 22, 1949. Revision received Jan. 17, 1950. To give all of the details of our experiments, studies, and experiences would fill a large book, but we were satisfied that our organization had done an excellent job, starting from scratch. You can appreciate our surprise when we discovered that we had added very little to an existing record. Attention was called to a footnote in a copy of "Carnegie Pocket Companion" year 1923. The note read: "Full information as to uses of H-Beams is given in pamphlet entitled 'Steel Mine Timbers.' " A search of our Engineering Library brought to light a pamphlet printed in 1911 showing extensive use of steel for this purpose. Except for welding in place of riveting, we have added very little to the designs in that book. We have, however, developed an experience which proves, at least to our own satisfaction, that steel mine supports pay off under the proper conditions. We are now convinced, in spite of the relatively high initial cost of materials, that steel sets, because of comparatively low installation cost, are actually cheaper than either treated or untreated wood sets, if they are properly designed and adapted. Several Sections in Use: Convenience guided our first experiments in steel sets, since for a number of years, we had used the 4-in. WF, 10 lb per ft section in 10-ft lengths as safety forepoles along with wood forepoles. This section replaced the 40-lb rail which had formerly been used for the purpose. Having the 4-in. WF sections on hand, it was natural that our first experiments in steel sets involved their use. Later, the rolling of the 10-lb section was discontinued in favor of the much stronger 13-lb section, which is now standard for both legs and caps in areas of no particular weight, but which, none the less, require permanent support. Our experiments involved the use of the 10- and 13-lb sections as legs and 6- and 8-in. I beams, 16 and 23 lb per ft, respectively, as caps. Experience soon indicated that, if the ground were heavy enough, and the opening wide enough to require a cap stronger than 13-lb, the 8-in, 23-lb should be used, eliminating the 6-in. I beam. We now know that the 8-in. WF section of the same weight, which we propose to use in the future, is considerably stronger for the amount of money involved. Comparative Strengths: Tables I to IV giving strengths of several species of timbers as compared with the structural sections that we now use have been prepared in accordance with accepted practice. Experience indicates that failure due to compression perpendicular to the grain of the wood does not destroy the effectiveness of a wood set frequently enough to be a practical factor. Therefore, no table of these values is included.

Jan 1, 1951

By N. N. Clark

Pachuca tanks are used widely as reactors for treating gold slimes, and for alumina digestion and uranium leaching. In some designs, slurry mixing in the tank is achieved by introducing air at the base of a draft tube, which is the full height of the tank. A buoyant air-slurry mixture rises in the draft tube and is discharged at the top. The slurry flows back through the bulk of the tank volume. Little information is available to predict the relationship between slurry flow rate in the draft tube, and the volume of air added at the base of the tube. Most current designs are based on the energy balance proposed by Lamont 25 years ago. Recent two-phase flow theory is used to develop a momentum balance for the flow in the draft tube, and a new, accurate design equation is derived. Bubble slip, frictional (wall) losses, entrance losses, and acceleration effects all contribute to the pressure gradient in the draft tube. None of these factors may be neglected under typical operating conditions. The new design equation accounts for all of these factors, and finds good agreement with Lamont's experimental example. Also, the new equation demonstrates that it is uneconomical to operate the draft tube with high airflow rates.

Jan 1, 1985

By I. Tamura, J. O. Brittain, T. Mura

Plain carbon steel in the cold worked or marten-sitic conditions has an internal friction peak at about 250 oC at a frequency of I cps. The influence of substitutional alloying elements on this peak was examined experimentally. The alloys were vacuum melted Co-, Cr-, Mo-, Ni-, and Si-iron (about 3 pct alloying elements), and carburized Si-iron. The internal friction of the alloys in the temperature range 30o to 500 OC was determined by means of a torsion pendulum. The 250 oC peak of the cold-worked alloys was lower in height than that observed in plain C-iron and steel. Carburized Si-iron in the quenched condition had a peak which occurred at a slightly lower temperature than in quenched plain C-steel, but the height of the peak was substantially greater than that found for the same alloy in the cold-worked condition. The activation energy of this peak for martensitic Si-steel was about 35 kcal per mol. ANNEALED a iron has two internal friction peaks due to nitrogen and carbon at 20o and 40o C respectively, at a frequency of 1 cps. If a iron is cold worked, these diffusion peaks become smaller and a new peak appears at about 250o C. The activation energy for the 250o C peak is in the range of 32 to 44 kcal per mol and has an average value of 38 kcal per mo1. It has been experimentally verified that both interstitial solute atoms and dislocations are necessary for the 250o C peak. 3 Wert has also shown that an incubation period precedes the appearance of the 250 C peak.4 With regard to quenched martensitic steel, Ke et al.596 observed two peaks at around 130o and 250o C. They conjectured that the 250o C peak in martensite was due to the same mechanism as the 250°C peak in cold worked a iron, and the 130°C peak was due to the nature of tempered martensite. They did not report the activation energy for these peaks. Chernikova7 found only one peak at about 200° C in tempered martensite. In a previous paperS we reported an activation energy of approximately 40 kcal per mol for the 250° C peak in plain carbon martensitic steels. Ichiyama8 found the activation energy to be about 36 kcal per mol for the 250° C internal friction peak in steels in the martensitic condition. The present authors proposed a theory for the 250°C peak for cold worked and quenched iron and steel.= The theory for the peak is based upon the addition of a strain-energy term to the free energy for the formation of a carbide precipitate due to the presence of a disclocation. The model employed for the relaxation process consists of the growth and solution of a carbide precipitate of critical size as a consequence of an oscillating dislocation. In this report, the influence of substitutional alloy ing elements on the 250° C peak is examined and the experimental results are discussed in terms of our theory for the peak. Most of the experimental work on the alloy steels was confined to the Fe-Si-C alloys.

Jan 1, 1962

By H. R. Peterson

The control of autogenous grinding circuits is very similar to the control of conventional grinding circuits. In both circuits the classifier must be operated to achieve the required degree of mineral liberation. Crude ore grade and grinding mill density are important in both circuits. The biggest difference between the control of the two circuits is the pronounced effect that crude ore changes have on autogenous circuits. The importance of crude grade, weight recovery, size and hardness is greatly magnified because the crude ore in the autogenous circuit is also supplying the grinding media. Crude ore sizing is a particularly critical factor in achieving efficient primary autogenous milling. Because of the above, computer control is advantageous for autogenous circuits. Changes in crude ore may necessitate rapid changes in the entire circuit control strategy, and only a computer can facilitate these changes. Also, the techniques of control are very different for conventional and for autogenous grinding. Set-point control is usually satisfactory in conventional circuits, but the multiplicity of varying conditions in an autogenous circuit usually require some type of computer optimizing search routine. Autogenous mills can be separated into two general types. In primary autogenous mills the media is obtained from the mill feed, and in pebble mills the sized pebble media is added separately from the material being ground. PRIMARY AUTOGENOUS MILL CIRCUIT CONTROL - FIGURE 1 Power Draw Primary autogenous mills are usually run at full motor loading so production will be at maximum. Therefore, power draw must be closely controlled; this is done by adjusting feed rate. The versatility of computer control is extremely valuable for power control, especially during starting and stopping. To bring the mill power up as fast as possible at

Jan 1, 1982

By F. W. Glaser, Benjamin Post

A LTHOUGH most transition metals form a wide variety of boride compounds, the existence of only one zirconium boride, ZrB2, had been established prior to this investigation.' The crystal structure and some properties of a hitherto unreported zirconium boride, ZrB12, are described in this paper. Only one other dodecaboride of a transition metal, UB12, has been reported up to the present.' Chemical analysis of the new compound showed 44 pct Zr and 56 pct B, compared with 41 pct Zr and 59 pct B computed for ZrB12. The difference is within the range of error of the analytical method employed. ZrB12 shows marked metallic properties. It is obtained as a fine black powder. Measurements of electrical resistivity were made at —79°C, + 22°C and +64°C. At 22°C the electrical resistivity is approximately 60 microhm-cm. Over this range the temperature coefficient of resistivity is +0.00162. The thermal conductivity at room temperature is 0.122 watts per cm per "C. The product of the electrical resistivity and thermal conductivity is therefore 8.05, which is not far from the normal Wiedemann-Franz ratio (approximately 7.5 at room temperature). These measurements were made on hot pressed samples which were not always high density specimens. The hardness of ZrB12 on the Rockwell A scale varies between 92 and 92.5. Crystal Structure Determination Single crystals of ZrB12 of a size suitable for X-ray diffraction analysis could not be obtained and powder samples had to be used. Filtered Cu radiation was used throughout. Powder diagrams were indexed on the basis of a face-centered cubic unit cell. After correction for film shrinkage, a Bradley and Jay extrapolation³ to ? = 90" indicated that a, = 7.408 ±0.002A. The volume of the unit cell is 406.5A.V he assumption that there are four "molecules" of ZrB12 per unit cell leads to an X-ray density of 3.63 g per cc. The measured density is 3.7 g per cc (as measured by the immersion method). Relative intensities of reflections were determined by integrating the intensities of diffraction peaks using the count register of a North American Philips wide range spectrometer. Intensities measured in this way showed good agreement with photographic intensities estimated visually using multiple film techniques. The usual Lorentz, polarization, and multiplicity corrections were applied to the observed intensity measurements. There are striking similarities between ZrB12, and UB12. The unit cell of the latter is also face-centered cubic and contains four molecules. a, = 7.473, compared with 7.408 for ZrB12. The radius ratio rB/rU is 0.57; rB/rZr is 0.54. In both ZrB12, and UB12 the four metal atoms in each unit cell are in special positions; only the boron positions need be determined. The latter may be inferred from the extent to which diffraction of X-rays by the 48 boron atoms reinforces or weakens the diffraction by the metal atoms. This effect is relatively much greater in the case of the zirconium compound. In their determination of the crystal structure of UB12, Berthaut and Blum' assumed holohedral symmetry (space group Oh5 , Fm3m) and reported that the U atoms are in positions 4(a): 000; 01/2 1/2; ½ 0 ½ ; ½ ½; the boron atoms were reported to be in positions 48(i) with x = 1/6: ½xx; ½xx; x½x; x½x; xx½; xx½; ½xx; ½xx; x½x; x½x; xx½; xx½

Jan 1, 1953

By J. E. Lawver, J. D. Raulerson, J. P. Bernardi, R. S. Hearon, D. Lynch, G. F. McKereghan

Despite recent economic problems, the future of the Florida phosphate industry appears optimistic. Florida has enormous reserves and will continue to produce a third of the world's phosphate supply simply by making changes in the present system of mining, beneficiation, waste disposal, and land reclamation. The geology and mineralogy of future deposits are discussed with reference to specific deposits. Lower ore grades, increasing power costs, and environmental regulations are necessitating development of new concepts of mining and matrix transportation. Because one of the ores to be mined in the future contains appreciable amounts of dolomite, research and development efforts are being concentrated on new techniques in beneficiation. Changes are being made in plant design to meet environmental and regulation standards. However, the expected new technology outlined for the industry depends on the geology and mineralogy of future reserves.

Jan 1, 1985

By M. Gensamer

IT has been suggested by a number of people that it would be worth while for some one to attempt to summarize or condense the proceedings of this symposium. This task has fallen to me as organizer and co-chairman. Its difficulty will be appreciated by anyone who attempts to read the whole proceedings. It is therefore with trepidation that I offer the following digest. In recent years there has been a renewal of interest in America on this subject of the cohesive strength of materials, and a growing appreciation of the need for a better theory of cohesion failure. The theories of elastic action and plastic action are well developed, particularly the former. The theory of plastic action is still in the course of development, but it is well along. Plastic action is terminated by cohesion failure and what is needed is a theory that will tell us when to expect the cohesion failure. In the past it has generally been assumed that cohesion failure will occur when a critical value of the maximum tensile stress has been reached. Many experiments have shown that this is not strictly true, and this symposium concerns itself with the failures of this simple hypothesis, and with the efforts that have been made to devise a more satisfactory theory. The most active contributor in recent years to knowledge in this field is Dr. McAdam, and he was asked to open the symposium with a summary or condensation of his papers and views. Undoubtedly it is presumptuous to attempt a still greater condensation, but perhaps it will be useful, because even his contribution to this symposium contains no summary, no concise statement of just what his contribution has bees. Dr. McAdam makes two main points. The first is that the cohesive strength is not a single valued quantity, but that it is a function of all three principal stresses and hence must be represented diagrammatically by a surface in a three-dimensional figure. Dr. McAdam has attempted so to delineate the cohesion limit, basing his

Jan 1, 1944

By J. C. Smock

The primitive mode of mining clay by open workings, in which the overlying beds of earth (commonly termed the " bearing ") were removed, and the clay then dug out by sinking shallow pits, is still the prevalent and almost universal mode of extraction. This is particularly true of our cretaceous and tertiary clays, which are generally earthy in character, and but slightly covered by drift and alluvium. The most accessible beds in many of our clay districts have been worked out, and clay miners are compelled to search for new outcrops, or to remove thicker beds of top dirt or bearing. Under this stimulus subterranean working, or mining proper, has been suggested. A brief notice of this new mode, as employed by Mr. Otto Ernst, near the head of Chesquake's Creek, three miles south of South Amboy, New Jersey, is here presented for your consideration. Previous to mining, the old mode of extraction, digging pits, was found to be too expensive, in' consequence of the heavy amount of top dirt and the excessively large amount of water in these overly

By J. C. Smock

THE primitive mode of mining clay by open workings, in which the overlying beds of earth (commonly termed the "bearing") were removed, and the clay then dug out by sinking shallow pits, is still the prevalent and almost universal mode of extraction. This is particularly true of our cretaceous and tertiary clays, which are generally earthy in character, and but slightly covered by drift and alluvium. The most accessible beds in many of our clay districts have been worked out, and clay miners are compelled to search for new outcrops, or to remove thicker beds of top dirt or bearing. Under this stimulus subterranean working, or mining proper, has been suggested. A brief notice of this new mode, as employed by Mr. Otto Ernst, near the head of Chesquake's Creek, three miles south of South Amboy, New Jersey, is here presented for your consideration. Previous to mining, the old mode of extraction, digging pits, was found to be too expensive, in' consequence of the heavy amount of top dirt and the excessively large amount of water in these overly-

Jan 1, 1875

ION exchange is one of hydrometallurgy's new tools, new in application, vet old in principle. Cation exchange between solution and a solid exchanger has been known for more than a century, but ion exchange is still in its infancy for metallurgical use. Still hampered by cost of media, it is faced with much development of actual physical handling. Growing consumption of the rarer metals and need to treat leaner ores are pushing extractive methods ahead. Public concern with stream pollution, or legal requirements, are forcing a clean-up of waste discharge. Industries are finding it vital to make some recovery from heretofore waste material to help pay costs of discharge treatment.

Jan 5, 1953

By T. L. Berger, M. C. lnman, M. F. Rose

AFTER shock loading, mechanical twinning has been observed by several authors1-4 for a variety of fcc metals and alloys. It has been shown2,3 that low stacking fault energy materials deform primarily by the formation of mechanical twins and stacking faults during dynamic loading. Further, Inman, Murr, and Rose2 have shown that a correlation exists between the average hardness and the volume percent of mechanically twinned material in stainless steel. It has been observed in nickel' that mechanical twins are produced during shock deformation if the peak pressure associated with the shock wave is greater than 350kbar. It is the purpose of this work to discuss shock-hardening mechanisms in nickel and to determine to what extent the initial condition influences the final response. The "flying plate technique" was used to generate planar shock waves with peak pressures as high as 710 kbar. The details of the technique5" have been discussed elsewhere and will not be repeated here. The material used in this study was polycrystalline nickel of 99.98 pct purity and had an initial grain size of 0.18 mm. Prior to any deformation, all samples were given a stress-relief anneal of 6 hr at 600°C in a vacuum furnace. After annealing, the initial condition of the samples was changed by cold rolling individual samples from 0 pct to a maximum of 80 pct reduction in thickness. This provided samples with controlled initial histories for shock deformation. Immediately after shock loading, the specimens were slowed and quenched by suitable arrangement of buffer material and water bath. This technique minimized specimen damage and the effects of shock heating on the samples. Since deformation twins in high stacking fault energy fcc metals are only produced at high stress levels, the initial defect configuration prior to mechanical twinning should greatly influence the number of twins formed. In fact, Zukas and Fowler7 have found that prestraining in iron and steel greatly suppresses the formation of mechanical twins during the shock deformation process. Following the methods of Warren and warekois8 and Cohen and Wagner,9 X-ray diffraction profile analysis was performed to determine the incidence of stacking faults and mechanical twins in the deformed nickel. Analysis was made on samples in the annealed, cold-rolled, shock-loaded, and cold-rolled—shock-loaded states. The estimated accuracy of the peak position measurements is *0.01 deg in 2?. Therefore the accuracy in the measurement of the relative peak shifts between the (400) and (222) diffraction line profiles is on the order of *0.04 deg in 2?. None of our measurements indicated peak shifts greater than 0.04 in 28. This would correspond to a fault density of -1 pct and sets the limit on the sensitivity of our instrument. Similarly, analysis of the shift in the center of gravity of the diffraction line profiles yields the minimum measurable value of the twin fault probabilitya to be -0.002. Fig. 1 shows mechanical twinning in nickel shock-loaded to 400 kbar. In this photograph, fault intersections are clearly visible. The thickness of the individual fault lamellae was determined from the image widths of their lines of intersections by the

Jan 1, 1968

By C. Gatlin, M. E. Chenevert

The effects of bedding plane orientation on the elastic constants and the yield strengths of three laminated rocks (one sandstone and two shales) and one isotropic rock (a limestone) were studied. The directional dependence of the elastic properties of these rocks was experimentally evaluated using a triaxial compression cell and auxiliary stress-strain measuring equipment. Symmetry of Poisson's ratios within the bedding plane suggested that horizontal isotropy exists, but the bedding planes do give rise to an appreciable difference between properties in the horizontal and vertical directions. For the three bedded rocks studied, Young's modulus was lower normal to bedding than along bedding. Yield strengths were determined at confining pressures from 0 to 12,000 psi in a triaxial compression cell. The rocks studied showed strength reductions as high as 40 per cent when the test specimen was oriented at 20°-30° to the bedding planes. The mechanical behavior of these rocks suggested that the rock properties of shear strength and/or coefficient of internal friction can vary with direction, depending on the particular rock tested. Tensile strengths were also measured and found to be lowest when failure occurred along bedding. This work shows that bedded formations exhibit sizable directional variations in both their elastic constants and yield strengths. It is suggested that these variations may be accounted for by using the "elastic laminate" model and the "variable coefficients" failure model. INTRODUCTION The nature of rock deformation at elevated pressures has been studied by many workers; papers by Handin,l,2 and Robinson3 illustrate the present state of knowledge. Most investigators have either chosen rocks which were as isotropic as possible (in order to avoid complications of data interpretation and analysis) or they have oriented their samples so that the effects of anisotropies (such as bedding planes) have been avoided. Of the studies performed, few were concerned specifically with mechanical anisotrop-ies. Griggs4 has presented limited data for specimens cut parallel, normal, and 45° to the bedding plane; he relates the strength anisotropy observed to the fabric (bedding) anisotropy. His tests were primarily concerned with large deformations (20 per cent strain); thus, no directional values of the elastic constants were reported. Handin has reported the results of similar experiments. Bott5has discussed rock strength anisotropies due to faults, cleavage, or bedding. He was concerned primari ly with determining the shear stress on such planes and did not mention the effect of friction. Jaeger6 later generalized Bott's work by taking friction into account and presented a limited theory for the failure of rocks having a "single plane of weakness", and also for rocks having a constant coefficient of friction, and a shear strength which varies with bedding plane orientation. Donath and Cohen,7 and Donathg have evaluated rock strengths from shale and slate specimens cut normal and parallel to bedding. A dependence of cohesive strength (7,) on the specimen orientation was also shown. Adler9 has also studied this problem and lists similar results. He assumes that all bedded rocks behave according to Jaeger's single-plane-of-weakness theory. Kalinin and Belorussov10 list results for strength tests parallel and perpendicular to bedding and use this information as a basis for hole deviation analysis. From the literature it is apparent that sedimentary rocks have been tested under widely varying conditions of stress; however, the assumption of isotropy is generally, but not always, made. Since geologic sedimentation often deposits sediments in very definite lavers.,. it seems that more svstema tic attention should be given to the possible effects of this natural bedding. Bedding, as used here, refers to visible regularities of grain size or orientation resulting from depositional processes. The mechanical strength anisotropies, which bedding may present, is not the only anisotronic property to be considered, since the elastic

Jan 1, 1966

By M. M. Slotnick

IT was once aptly said that a sign of approaching senility is ceasing work on a subject and beginning to talk about it. Perhaps that explains why, after many years in which part of my duties has been the training of college men in various branches of petroleum exploration geophysics, I have now begun to talk about it. In making an outline of what I believe ought to be discussed under the general heading of the title, I found it almost impossible to subdivide the ideas into an ordered set of discrete subjects. Rather, the pertinent remarks seemed to interlock almost everywhere. The consequence is that it will be necessary to start with the conclusions and then try to justify them by jumping back and forth. However, based on the types of men with whom I have had to deal, the subject naturally divides itself into two parts. In the first part, I should like to deal with the case of those undergraduates whose natural bent is toward the physical sciences and who may decide to enter the geophysical fold as a career. The other part will deal with those many men, geologists and engineers for the most part, who have drifted into exploration geophysics by one means or another, and whom it is necessary to train for geophysical work while they are occupied in their routine jobs. Here it may be in point to remark that most men in exploration geophysics at present have been developed from precisely the latter group, and that the problem of training here is of great importance even though, in this paper, it will perforce occupy the secondary place. TRAINING OF A GEOPHYSICIST The outstanding reason for the perplexing problem on the training of a geophysicist is that ideas differ on the answer to the question: "What is a geophysicist?" In any of the scientific "specialties," like physics, for example, it is relatively simple to pigeonhole a man as being qualified to call himself a physicist. That appellation applied to an individual does not mean that he has mastered only the branches of intellectual endeavor usually associated under the broad name of "physics." We expect him also to have a more than mere acquaintance with mathematics and chemistry and some understanding of most of the other sciences. But note this important point-we expect our physicist, whom we have chosen as an example, to be intelligently trained so that, if necessary, he can and will know how and where he can get the proper information on a subject in which he is not a specialist; he will know how to absorb that information and turn it to his uses. It seems to me that this is the outstanding characteristic of a man who can truly call himself a scientist: that he is a specialist in one of the broad branches of science and that he has enough training and discipline in the scientific approach so that, when called upon to do so, he can intelligently absorb knowledge from another bordering science (and all sciences not only border upon one another to some extent, but more often, overlap one another), and

Jan 1, 1941

By C. S. Smith, L. H. Beck

KNOWLEDGE of the Cu-Zn constitution diagram was critically examined in 1944 by G. V. Ray-nor,1 who suggested the diagram reproduced in Fig. 1 as the best evaluation of available data. No pertinent work on the constitution has been published since that time, although a number of authors have discussed transformation kinetics and theory. Despite the large amount of work that has been done on the constitution of these industrially important and scientifically interesting alloys, minor uncertainties still exist. For example, it is still not possible to say definitely whether a two-phase region exists between the ordered and disordered forms of the 8 phase. A careful re-examination of the phase boundaries in this part of the diagram was therefore undertaken. Two methods were selected for the new investigation—quantitative metallography for the higher temperatures and precision lattice parameter measurement for lower temperatures. Because of the relatively narrow two-phase regions flanking the ß phase in these alloys, quantitative metallography is particularly suited for their examination, since the relative amounts of the two phases are very sensitive to their compositions. The method, however, is useless below about 350°C because of the inadequate resolution of the two constituents. Below 400°, however, the X-ray diffraction method is applicable, although it is of somewhat lower sensitivity in this system. The changes of composition that occur during quenching from above about 500°C entirely vitiate X-ray measurements at room temperature though they do not affect metallographic area measurements. The two methods overlap and supplement each other admirably. Both methods depend on the attainment of equilibrium composition of the two phases in a more or less intimate mixture and thus avoid the difficult problems of nucleation and long range diffusion involved in the conventional metallographic bracketing method. The alloys were melted from a master alloy made from re-electrolyzed cathode copper and Horsehead 99.99 pct Zn. Melting was done under a cover of either borax or charcoal and the alloys cast into a 7/8 in. sq graphite mold for the a-ß alloys or a 3/8 in. diam cylindrical graphite mold for the ß-? alloys. The a-ß alloys were rolled at 750°C to 5/8 in. sq; annealed for 24 hr at 800°C and quenched; then rolled and swaged at 200°C to 3/8 in. diam rods, annealed 24 hr at 200°C, quenched and cold rolled 2 pct reduction. This treatment was intended to obtain a small grain size and to produce many nuclei of the minor phase for growth on subsequent heat treatment. The unworkable ß-? alloys were given preliminary treatment by sealing in Vycor tubes in vacuum and annealing for 4 hr at 800°C followed by cooling in air. Samples of homogenized alloys were checked spectrographically for impurities, but the principal components were determined on samples subsequent to heat treatment. The impurities analyzed averaged approximately as follows: Ag, 0.0002 pct; Fe, 0.004; Si, 0.0008; Cd, 0.005; Mg, 0.0002; and Pb, 0.002. For metallography, samples of appropriate composition were cut into rods 5/8 in. long, sealed in pyrex tubes in vacuum and annealed for eight weeks at temperatures of 470°C and below, two weeks at 480°, 500°, and 600°C, and 4 hr at 700°C, followed by quenching in cold water. Temperatures were accurate to ±2°C. The cylinders were then machined to 8.7 mm diam and a slice weighing 1.5 g cut with a thin saw transversely from the center of each. This

Jan 1, 1953

By M. C. Leverett, W. B. Lewis

The dynamic behavior of a multiple fluid system is completely describable in terms of driving forces and resistances to flow. The latter are proportional to the viscosity of the fluid under consideration and inversely proportional to a property of the system termed the " effective permeability " to that fluid, a property therefore defined by this relation. Since three phases are usually present in oil reservoirs, it is essential to know the effective permeabilities to the several fluid phases, and the relationship between the composition of the fluid in the pore space and that of the flowing stream, in order to handle satisfactorily certain problems of oil production. In this regard, there are many unknown factors and parameters, and many that can be evaluated only indirectly. However, it is expected that work along lines similar to this present undertaking will help materially in solving these problems. .. . . Previous workers in this field have investigated the two-phase systems, water-gas,' water-oil2 in unconsolidated sands, and water-gasg in consolidated sands. The extension of the study of the flow of heterogeneous fluid systems from two to three phases involved only slight changes in technique. The apparatus used in the present work, except for slight changes to be described, was that used by Leverett in his water-oil experiments.~ Correlation and interpretation of data were made by methods analogous to those used in two- phase work. The relative permeability to a phase—the effective permeability divided by the permeability of the system to a homogeneous fluid—was employed throughout in correlating the rate of flow of that phase with the composition of the pore space. Quantitative measurements of two independent physical properties of the system were required to determine the composition of the pore space. As in the two-phase work, the fraction of water was determined electrically, The gas fraction was determined by measuring changes in volume accompanying measured pressure changes. Suitable account was taken of the solubility of the gas in the liquid phases, and of the vapor pressure of the water phase. Since this work was exploratory in nature, no attempt was made to obtain highly accurate numerical results. Reasonable precision and reproducibility were sought. Experimental Procedure variables Considered.—Of the properties of the fluids, the oil viscosity is most likely in practice to vary widely. Variations in oil viscosity were therefore included in this work, but variations in other properties of the fluids are as yet unexplored. It appears unlikely that the normally encountered variations will produce significant changes. ~h~ observations were made at fairly high pressure gradients, no attempt being made to detect a variation of the relative permeabilities with pressure gradient. It should be pointed out also that since most of the data were taken on one sand size only, it call Only be assumed at present that changes in

Jan 1, 1941

By W. B. Lewis, M. C. Leverett

The dynamic behavior of a multiple fluid system is completely describable in terms of driving forces and resistances to flow. The latter are proportional to the viscosity of the fluid under consideration and inversely proportional to a property of the system termed the " effective permeability " to that fluid, a property therefore defined by this relation. Since three phases are usually present in oil reservoirs, it is essential to know the effective permeabilities to the several fluid phases, and the relationship between the composition of the fluid in the pore space and that of the flowing stream, in order to handle satisfactorily certain problems of oil production. In this regard, there are many unknown factors and parameters, and many that can be evaluated only indirectly. However, it is expected that work along lines similar to this present undertaking will help materially in solving these problems. .. . . Previous workers in this field have investigated the two-phase systems, water-gas,' water-oil2 in unconsolidated sands, and water-gasg in consolidated sands. The extension of the study of the flow of heterogeneous fluid systems from two to three phases involved only slight changes in technique. The apparatus used in the present work, except for slight changes to be described, was that used by Leverett in his water-oil experiments.~ Correlation and interpretation of data were made by methods analogous to those used in two- phase work. The relative permeability to a phase—the effective permeability divided by the permeability of the system to a homogeneous fluid—was employed throughout in correlating the rate of flow of that phase with the composition of the pore space. Quantitative measurements of two independent physical properties of the system were required to determine the composition of the pore space. As in the two-phase work, the fraction of water was determined electrically, The gas fraction was determined by measuring changes in volume accompanying measured pressure changes. Suitable account was taken of the solubility of the gas in the liquid phases, and of the vapor pressure of the water phase. Since this work was exploratory in nature, no attempt was made to obtain highly accurate numerical results. Reasonable precision and reproducibility were sought. Experimental Procedure variables Considered.—Of the properties of the fluids, the oil viscosity is most likely in practice to vary widely. Variations in oil viscosity were therefore included in this work, but variations in other properties of the fluids are as yet unexplored. It appears unlikely that the normally encountered variations will produce significant changes. ~h~ observations were made at fairly high pressure gradients, no attempt being made to detect a variation of the relative permeabilities with pressure gradient. It should be pointed out also that since most of the data were taken on one sand size only, it call Only be assumed at present that changes in

Jan 1, 1941

By H. C. Howarth

THIS paper gives observations on ground movement and subsidence resulting from pillar drawing in the Lick Run section of Montour No. 10 mine of the Pittsburgh Coal Co. adjacent to solid coal owned by the U. S. Bureau of Mines at its Experimental mine in Snowden Township, Allegheny County, Pennsylvania. The investigation was planned by George S. Rice, chief mining engineer of the Bureau, who arranged the necessary cooperation with Dr. L. E. Young, vice president of the Pittsburgh Coal Co. Engineers of that company placed permanent monuments on the surface to establish the boundaries of the coal owned by the Bureau and to furnish fixed points to which all levels were referred. Engineers of the Experimental mine staff then covered the ground under observation with a checkerwork of monuments made of oak pegs set into the ground at 50-ft. intervals in two directions at right angles to each other. The level of these pegs was determined first from Dec. 16 to 30, 1929; again from May 25 to June 5, 1930, and finally from July 7 to 15, 1931. Observations were then discontinued because work had been stopped temporarily in this part on Montour 10 mine.

Jan 1, 1933

By Frank S. Hurley

To comply with the California Mine Safety Orders pertaining to transportation of mine workers over mine railroads, the management of the New Idria mine in San Benito County, Calif., designed special man-cars. The new regulations, dated October 1958, make it mandatory for mine man-cars to be designed for carrying five or more men to and from the mine workings. At the New Idria mine, largest single producer of mercury in the U.S., each shift normally employs about 70 men. However, with the possibility of a future increase in the work force, seven man-cars were constructed with a total carrying capacity of 84 men. The general design of the mine man-cars was dictated by safety regulations plus the physical characteristics of the mine-low headroom, limited side clearance in haulageways, and track irregularities due to ground swells. The cars measure 10 ft long, 44 in. wide, and 50 in. high and were built at an average cost of $450 per car. All assembly work was done at the mine site.

Jan 7, 1960

By Arnlf Muan, Bert Phillips

The quenching technique has been used for- a study of phase velntiorzs within the composition triangle 2CaO.Fe2O3-FeO.Fe2O3 Fe2O3 of the system Ca-Fe-O. Desired total compositions of sanzples were attained by weighing of starting materials in required proportions and keeping them in sealed 80 pct Pt 20 pct Rh tubes during equilibration .runs. The liquidus surface has been delineated. the existence of two ternary compounds has been established, and seven ternary inwariant situations have been determined. ONE unit within the research program on refractory oxides in progress in our laboratories is the study of phase relations in the system Ca-Fe-Si-O. The present paper deals with the ternary system 2CaOFe2O3-FeO.Fe2O3-Fe2O3, which is only a small part of the enormously complex quaternary system. Many of the phases occurring in iron ore sinter products have compositions which can be closely approximated within this ternary system, and a knowledge of stability relations existing among these phases may be expected to be a useful guide for improving sintering operations. Two fundamentally different experimental approach es are commonly used in studies of systems containing iron oxides, both permitting control of the oxidation state of Fe. One method consists in keeping constant the oxygen partial pressure of the gas phase in equilibrium with condensed phases (liquid and crystalline). In the other method, which is the one used in the present investigation, the total composition of condensed phases is kept essentially constant by keeping the samples in a gas-tight container. The details of this experimental procedure will be described in a later section. PREVIOUS WORK Extensive studies of phase relations in the bounding binary system FeOFe2O3-Fe2O3 have been reported by Greig, Posnjak, Merwin, and Sosman,' by Darken and Gurry,2, 3 and recently by Phillips and Muan.4 A diagram summarizing the results of these studies is shown in Fig. 1. Particular attention is

Jan 1, 1961

By M. J. McPherson

Having worked on the thermodynamics of air/liquid-water mixtures passing through the surface fans of deep mines, I find this paper of great interest and congratulate the authors on producing it. There are two matters, however, deserving discussion. First, the authors have described the classical theory of fog formation with fogging occurring at "supersaturation." In fact, the process of fog formation begins well below 100% humidity. The more strongly hygroscopic nuclei in the atmosphere will attract water molecules and begin to grow at a relative humidity perhaps as low as 70%. The process is a dynamic one with both condensation and evaporation taking place throughout the mixture on microscopic liquid surfaces. As saturation is approached, the rate of condensation accelerates rapidly producing the familiar reduction in visibility. Hygroscopic nuclei are present in all natural atmospheres and under the appropriate conditions of pressure and temperature, will produce clean fogs. However, if the air is polluted by particulates from combustion or other processes then the resultant coagulation with growing liquid particles may produce dense (and sometimes photochemical) smogs. It is this process that is likely to occur in underground mines when moist air is cooled below dew point. Second, the authors have summarized very well the individual measures that might alleviate the problem. In particular, I agree that neither heating nor refrigerating the air, by themselves, provides a satisfactory solution. However, there is a combination of these that provides a neat and effective control of fog formation. This involves a small, self-contained refrigeration unit within a duct but without the usual external heat rejection facility. The air is cooled below dew point and, hence, dehumidified on passing over the cold evaporator coils. The heat from the condenser is rejected back into the air down-stream from the water eliminator, as shown in [Fig. 1]. The duct configuration can be designed to create good mixing at the outlet.

Jan 1, 1984