Search Documents

The authors of T.P. 4179 have conducted a large number of experimental water floods, and the data are reported in a very clear manner. These data show significant variations of residual oil saturation with changes in wettability, interfacial tension, flooding rate, and oil-water viscosity ratio. Furthermore, some of the data obtained cover a range of variables not previously reported in the literature. It is our opinion that at least some of the observed variation in oil recovery can be obtained only in floods made under conditions identical with those used by the authors. There are other systems which may be said to have the same wettability, but which exhibit an entirely different qualitative dependence of oil recovery on the experimental variables. In this regard, we would like to direct attention to several items which we feel are not given sufficient consideration in the paper. The first of these items has to do with wetting equilibrium. A survey of the current literature will reveal that little is known, and even less is understood, about wetting equilibrium. This is particularly true of the relation between contact angle measurements made under static conditions, and the wettability existing under the dynamic conditions of floods carried out at relatively high rates. We feel that this is a very important consideration, particularly in the floods the authors performed under what they consider to be "water-wet" conditions. It is our opinion that wetting equilibrium did not exist in these floods, except possibly at the very lowest rates. This opinion is in part based on some flooding tests we have made which are very similar to some of those described by the authors. These floods were made in unconsolidated cores, 6 in. long and 13/4 in. in diameter, made up of carefully graded glass spheres of the approximate size of the sand grains used in the subject paper. The cores were mounted vertically, and distilled water was used to displace a refined oil equivalent to the authors Soltrol C. The glass spheres had previously been carefully cleaned so that they were strongly wet by the water. The floods were made with and without an interstitial water saturation. When interstitial water was present, the solid surfaces were mostly covered with water prior to injecting the flooding phase. Consequently, a condition very near wetting equilibrium existed throughout the flood. The data in Fig. A show that under these eircumstances, rate had no influence on residual oil at flood-out, over the range of rates studied. On the other hand, in the absence of interstitial water, the surfaces are all covered with oil before the displacement. To achieve wetting equilibrium the injected water must displace the oil from the surfaces themselves. This is not a fast process. Therefore, the effective dynamic wetting condition in floods of this type must depend upon the flooding rate. When the flood rate is very low, compared to the rate at which wetting equilibrium is attained, the residual oil saturation at flood-out is essentially the same as the residual obtained when interstitial water is present. This is shown in Fig. A, and occurs because the dynamic wetting conditions are the same in both cases. However, at moderately high flooding rates, the rate has an important bearing on the amount of oil recovered because in this case the attainment of surface equilibrium is the slow step. We believe that, in the absence of an interstitial water saturation, oil recovery varies with rate because of the reasonably slow approach to wetting equilibrium which occurs during the displacement. In fact, as the rate is increased, the oil recovery performance indicates the core is becoming progressively less water-wet. At the highest rate there is even considerable simultaneous production of oil and water after breakthrough. This does not occur at the lower flooding rates, nor is there appreciable simultaneous oil and water produc-

Jan 1, 1957

By T. B. Armstrong

Electrical energy conservation sees that service facilities are operated only when needed and that production equipment is operated under an optimum condition. Specific energy consumption (kw-hr per tonne) is not regularly recorded for comminution circuits because of variations in ore characteristics and the low grinding efficiency (0.1 to 2.0%) of the equipment. Improved data acquisition can produce meaningful results. Particle size monitor systems and density gauges permit comparison of energy (kw-hr) and production (tonne) for a "fixed" condition. Finding the operating condition producing the lowest unit energy consumption provides a target for an effective energy management program.

Jan 1, 1982

By L. L. Davis

Current research by the US Bureau of Mines to develop technology for improving efficiency and productivity in metal/nonmetal mines is described. The research program addresses a wide variety of problems associated with each of the major categories of mining: underground mining, surface mining, m situ mining, and premining investigations. An overview of the Bureau's research activities is given with emphasis on underground mining. In particular, two innovative and promising concepts currently under development are described: a unique shaft sinking system that uses an impact hammer for rock fragmentation, and a low-profile portable crusher for underground hard-rock applications.

Jan 1, 1982

By Henry S. Munroe

THE plan of organizing a summer class of students of the School of Mines, for the practical study of mining and miner's work, received at the outset the following cordial indorsement : I have thought over the plan proposed by you of taking the students to the mines during the summer, and of having them actually take part, under the direction of skilled workmen, in all the various kinds of mining work; and of using them as a carps of engineers to make Inside and outside surveys, particularly with a view to the detailed study of the geology of the mine. I have no hesitation in saying, that if the students have been previously instructed in the theoretical part of their studies, by lectures and practice during the winter, the plan would be an admirable one. Of course experience will suggest modifications of detail. From the work you have done at our mines this spring, I feel sure that you would be perfectly competent to carry out your plan, and I shall gladly aid you in any way I can. "Yours, sincerely, T. B. Coxe." The plan of the proposed summer school thus indorsed by Mr. Coxe was adopted by the trustees of Columbia College, and an appropriation of one thousand dollars, or so much thereof as might be necessary, was voted for the experiment. A volunteer class of thirteen students was formed, and the first summer school was held at Drifton, in July and August of that. year (1877). The following extract, from an editorial notice in the Engineering and Mining Journal, of August 11, 1877, will give an idea of the 'organization of the school and the work required of the students. "The students, on reporting to Professor Munroe, were divided into squads of two or three men each, and on Monday, July 2d, were assigned to the Care of skilled miners, selected for the purpose by the mine boss, for instruction in gangway work. Half of the students worked in the morning and the other half in the afternoon, one squad at a time with each miner. The times of going and coming to and from work were so arranged that each student spent four to four and a half hours in the mine each day. While in the mine they assisted the miner to load his car, thereby learning readily to distinguish 'slate ' and

Jan 1, 1881

By Nev A. Gokcen

DISCREPANCIES and scattering in the equilibrium data on the reactions of hydrogen, and CO with dissolved oxygen in liquid iron are un- duly large. Available experimental results on the reduction of liquid ferrous oxide, i.e., wüs-tite, with hydrogen and CO are questionable, as pointed Out by Darken and Gurry'l Direct determinations of the solubility of oxygen in liquid iron are subject to errors which cannot be easily reduced by further experimental refinements, and therefore an accurate but indirect method is highly desirable. The purpose of this investigation was, therefore, 1)

Jan 1, 1957

By V. R. Thompson, R. C. Westgren

In a recent paper,1 the solid-solution strengthening of tungsten and tantalum in a portion of the W-T;-MO-C~ alloy system was described. Additions of tantalum and columbium to tungsten led to significant strengthening, and the introduction of dispersions into these alloys was suggested as a means of further increasing strength. Dispersion strengthening of columbium and molybdenum alloys has been studied extensively.2-4 The approach used to dispersion-strengthen molybdenum alloys appeared equally suitable for tungsten alloys, and, therefore, a brief study was undertaken to determine to what extent the introduction of carbide dispersions would strengthen a solid-solution tungsten-base alloy. A base composition of tungsten and 10 to 12 pet Cb was selected; previous work1 had shown that the tensile strength of this solid-solution alloy was 50,000 psi at 3000°F. For the study of the effects of small additions of

Jan 1, 1964

By F. C. Miller

The metallurgical fuel of Colorado, Utah, and New Mexico has been a Veiny tardy member in the caravan of western industrial progress. The history of western coke has naturally been closely related to the development of the metallurgy of iron and steel and the precious metals, in the State of Colorado. It was at Leadville, with a population of 300 in 1877, that the Sentinel was published by Richard S. Allen. The Sentinel gave very full accounts of the various mineral discoveries at the new town of Leadville, which found their way to the more widely circulated journals of the East, and attracted the attention of many people. At the close of 1878, a census slowed a total of 5040 persons. The first smelter was established in 1877, at Malta, two miles from Leadville, by A. R. Meyer, but was not successful. It was succeeded by the Harrison Reduction Works, in 1878. The La Plata began with one furnace in June, 1878, and in 1879 had four furnaces in active operation. These furnaces used charcoal for fuel, and, because of hot tops, suffered a tremendous loss in lead and silver. This difficulty was overcome by the erection of 50 single-bank 10-ft. beehive ovens at Crested Butte, Colo., in 1880. The slack coal sent to these ovens was very pure, and yielded a coke carrying as little as 4.5 per cent. ash. Among the pioneers in the Leadville district were Grant, Eddy, James, Billings, Eiler, and Dickson. To these men the West owes the present expansion of its mining industry, and the erection of metallurgical processes for the treatment of precious metals. On Mar. 1, 1876, Pueblo was connected to the Atchison, Topeka & Sank Fe by the Pueblo & Arkansas Valley branch. The first smelter was erected in Pueblo by Mather and Geist. This modest plant grew into the immense Pueblo Smelting and Refining Co., now a part of the American Smelting and Refining Co. Coke for these small furnaces was made from unwashed Engleville coal, in 186 single-bank 12-ft. ovens at El Moro, in the Trinidad district, and it was not uncommon for the percentage of ash to exceed the percentage of fixed carbon in the coke. On Jan. 23, 1880, the Colorado Improvement Co. consolidated

Jan 1, 1920

By E. J. Quinn, M. F. Fogler

In a recent paper, Rawdon and Mutchlerl gave some exceptionally interesting results on the Brinell and scratch hardness of severely cold-worked metals. In their work, they found that, on continued cold rolling, the metal hardened up to a particular point and then reversed and became softer; this was true for both Brinell and scratch hardness values. The generally reported behavior2 of metals, with respect to Brinell tests on cold-worked material, is that the metals harden up to a certain point and then, on further cold rolling, no change in Brinell hardness occurs. Jeffries and Archer3 state that there is little difference between the scratch hardness of annealed and cold-worked metals; the work of Faust and Tammann4 also indicated no difference between the hardness of annealed and cold-worked copper. Rawdon and Mutchler found, when they plotted the reduction ratio (initial thickness divided by thickness after rolling) against the hardness value for the cold-rolled material, that the hardness number increased up to a reduction ratio of about 3 and then decreased and became even smaller than that for the annealed metal. This behavior was reported for both scratch and Brinell hardness; Figs. 1 and 2 show their results for Brinell hardness on the metals for which they published data. This is an exceptionally interesting phenomenon, if it occurs under all conditions of rolling, and would have an important bearing on the practice of cold

Jan 1, 1925

By Frederic E. Carter

THE history of all the civilizations of the Eastern Hemisphere is underlaid and interwoven with the story of gold. Great nations rose, welded by the hand of the conqueror, flourished gloriously because of the wealth of gold inevitably attracted to them, only to fall, either through the sapping of their original virility by the softer living their material prosperity made possible, or by wars made upon them by enemies who craved possession of what was theirs. Imposing fleets sailed the seas, seeking gold or tangible wealth that might be converted into gold. Men suffered untold tortures in its quest. It sent Columbus out into unknown oceans, caused the migration of hordes of people from our Atlantic to our Pacific seaboard in '49 and accelerated the final subjection of our last frontier, probably by as much as a century. The mystic may see both something sinister and something beneficent in this metal that has played such a tremendous part in the shaping of the destinies of men. It has showered blessings and taken them away. It "hath deposed the mighty from their seats and hath exalted men of low degree" and, sardonically, reversed the order yet again. Its peculiar color, its incorruptibility, and its rarity all have contributed to excite the imagination of all races of men. In the Eastern Hemisphere and now in the entire modern world, the predominant emotion excited by gold is avarice. But in the social and economic organization of the civilizations native to the western half of the world, gold has a far different history. Before the advent of the white man, these sun-worshipping peoples saw in the permanently

Jan 1, 1953

By E. E. Gardner, P. A. Schumann

A description of a new four-point probe configuration which permits measurement of epitaxial layer resistivity is given. An analytic solution to the potential distribution due to a point current source on a multilayered structure is briefly described. Typical solutions for this probe configuration are presented. Probe spacing, layer thickness, substrate resistivity, and substrate thickness enter into the calculation. Correction factors for typical cases are given. A brief description of the construction of a probe which can achieve a small spacing of 15 is presented. The prohe is constructed so that all points are adjustable by micrometers and the probe spacing and configuration can be easily altered. Measurements of layer resistivity with the four-point probe are compared with those taken with the three-Point probe and diode-capacitance techniques. TWO techniques of obtaining profiles of N/N+ epitaxial structures are given. The reproducihility of the probe spacing and resistivity measurement is discussed. The effects upon the resistivity measurement of errors in the measurement of the lager thickness, substrate resistil)itv, and substrate thickness are presented. SINCE its introduction by valdes' in 1954, the four-point probe has been the most widely used tool for determining semiconductor resistivity. Its usefulness ranges from the evaluation of bulk semiconductor ingots to the characterization of impurity profiles in diffused structures. In general the four points, two current probes and two potential probes, are placed on one surface of the material being tested either in an in-line array or in a square array. Numerous correction factors1 8 have been worked out for these configurations which are dictated by the finite geometry of the sample being tested. One method of evaluating thin wafers has been proposed which has two probesg on each side of the wafer. Further modifications have added a fifth'' and a sixth" probe. One paper1' has discussed the accuracy of the four-point probe and the precautions necessary in its use. With the exception of the method where two points are placed on opposite sides of the wafer, the four-point probe is restricted to evaluation of wafers with a homogeneous resistivity or to the case where an isolating junction exists between the substrate and the layer (epitaxial or diffused) being evaluated. Due to the relative resistivities and thickness, the resistance of the epitaxial layer is much greater than that of the substrate, and consequently a majority of the current flows through the substrate. The potential distribution at relatively large distances from the current sources is determined by the substrate resistance, and hence the AV/I value is a measure of the substrate resistivity and not that of the epitaxial-layer resistivity. In the immediate vicinity of a current source the potential distribution is determined by the layer resistivity among other factors. Consequently, if the potential probe is placed very close to the current source, then with appropriate correction factors it is possible to determine the layer resistivity. This was the theoretical basis for using two closely spaced probes on opposite sides of an epitaxial wafer. However, due to mechanical problems, it is desirable to place the four probes on the same side of the wafer. This paper discusses the potential distribution in

Jan 1, 1965

By D. A. Sangrey, D. Marcus, S. A. Miller

A methodology was developed wherein the increase in compressive strength, mineralogical changes, and pore water composition were studied simultaneously as a function of moisturized spent shale curing time. From these results the relationship between the nature of cementation process and the composition of pore water was established. Heavy metals were entrapped in the cementing constituents and the pore water became mainly a solution of alkaline sulfates. The specific data are applicable only to the material studied. But the methodology and general conclusions are useful for evaluating the environmental factors in spent shale disposal and expected leachates composition.

Jan 1, 1986

C. G. Dunn (Generai! Electric Research Laboratory)— The author is to be commended on his attempt to calculate the residual strain energy from information on the dislocation density within the subgrains and a surface energy associated with the subgrains. However, much closer agreement between a calculated critical size of a nucleus and the observed size of grains that did not continue growing can be obtained if a reasonable correction is made in obtaining the energy of the surfaces of the subgrains. For example, since the sample is a single crystal with a cold-rolling reduction of 70 pct in thickness, one needs either an average disorientation for this or an average subgrain boundary energy rather than the 2.5 deg disorientation of a bent crystal, which was used by the author. From either the Laue photographs of the author or the pole density plot of Koh and Dunn 16 for a (113) [332] cold-rolled crystal the

Jan 1, 1961

By S. C. Lee

An uncoupled thermoviscoelastic finite element formulation with an application to Underground Coal Conversion (UCC) is presented. An incremental solution procedure with an implicit time stepping scheme is used under the thermorheologically simple material (TSM) postulate. The presented formulation, for a homogeneous and isotropic medium, is employed in the simulation of the UCC post-burn phase. Temperature, displacement, stress, and failure responses under thermomechanical loading are predicted. The solutions for the selected field problem indicate potential roof collapse, stress relaxation, and modest surface subsidence with a progressive thermal and failure front. The corresponding thermoelastic responses with temperature- dependent elastic properties are also presented and compared with the thermoviscoelastic results.

Jan 1, 1984

By James D. Sisler

Among the various studies made by the Coal Fact Finding Commission, appointed by President Warren G. Harding in 1922 to investigate all phases of the coal-mining industry in the United States and to report to Congress, was one concerning the amount and nature of losses in mining bituminous coal in the eastern part of the United States. This study was carried on under the direction of the U. S. Bureau of Mines. The writer was appointed field engineer to investigate the problem in Ohio, Pennsylvania and West Virginia. Some 400 mines were studied in these three states and conclusions were drawn from many sources of data. The summary report written by George S. Rice and J. W. Paul states that "the field reports indicate that the recovery in Ohio will remain about as at present, except in the Belmont district; whereas in Pennsylvania it will gradually improve, and in West Virginia it will improve rapidly." Since 1922, the writer has been interested in gathering material to substantiate or contradict these prophecies. Nature of Coal Losses There are six general causes of losses of coal in mining: (1) coal left on the roof and bottom; (2) coal lost in room, entry and panel pillars; (3) coal lost in oil-well or gas-well pillars; (4) coal lost under buildings, railroads and boundaries; (5) coal lost in handling and prepayation, underground and surface; (6) coal lost by rolls, thin or dirty areas and under streams. Local economic aspects that dominate the type of mining conditions determine to some extent whether certain losses are avoidable or unavoidable. In general, however, unavoidable losses include coal lost in the protection of buildings, streams, railroads, restricted properties and around oil and gas wells. Barrier pillars and other safety pillars are unavoidable losses as long as their size does not exceed the minimum for adequate safety. Natural physical conditions beyond human control, such as rock faults, clay veins, partings and binders, bad top and bottom, rolls and horsebacks, cause unavoidable losses. Unavoidable losses

Jan 1, 1931

By C. S. Barrett, A. Smigelskas

J. T. NORTON*—I think Mrs. Smigelskas Fischer has done a splendid job in working out the pole figures from rather difficult photograms which are common to beryllium. Is there not a mistake in Fig 2 in that the pole figures B and C have been interchanged? A. SMIGELSKAS FISCHER (authors' reply)—Yes, there is such an error in the labeling of the pole figures of Fig 2. The correct plane for Fig 2b and 2c is the plane in parenthesis above the figure numbers and not that in the figure subtitle. J. T. NORTON—Also, I would like to mention another method of obtaining the data for pole figures which would be particularly applicable to this problem. It is a method which has been published only

Jan 1, 1950

By E. B. Thornhill

Discussion of the paper of E. B. THORNHILL, presented at the San Francisco meeting, September, 1915, and printed in Bulletin No. 104, August, 1915, pp. 1653 to 1670. D. B. HUNTLEY, Oakland, Cal.-About 15 years ago it chanced to be my lot to cyanide some mill tailings, assaying about $5 per toll in gold and, a few cents in silver. It was in southern Idaho, a. desert region where costs are nearly as large as in central Nevada. We knew that we had a lot of tailings that had been amalgamated and contained about 1 lb. of quicksilver per ton. We knew that we would dissolve some of the quicksilver when we cyanided them with say 0.25 per cent. cyanide solution. We figured (optimistically) that the cyanide would dissolve all of the quicksilver, and we thought to capture all of that, 1 lb. per ton; and we figured out profits as partly gold, partly silver, and partly quicksilver from the recovery in working those tailings. Actually, however, we did this: We had a battery of three large, old-fashioned silver-mill retorts. We retorted our zinc-dust precipitate, recovering about ¼ lb. of quicksilver per ton treated. That was only a loss of 75 per cent. of what we originally had, but still it was profitable by virtue of the conditions. I mention it partly to call attention to the crude old way of doing it, and partly to call attention to how chemical methods for recovering quicksilver have developed in the last 15 years.

Jan 12, 1915

By Wilbur I. Duvall, Thomas C. Atchison

Over the past ten years a series of investigations have been conducted to determine some of the physical processes involved in breaking rock with confined concentrated charges. Detailed discussions of many of these investigations have been published elsewhere.1-6 Laboratory experiments made by other investigators using Hopkinson pressure-bar techniques have shown that solid materials are fractured in tension by the reflection of an incident compressive stress pulse at a free surface.7-12 In these tests a small charge of explosive is placed in contact with one end of a bar. Detonation produces some plastic flow and crushing of the bar near the charge and generates a compressive stress pulse that travels along the length of the bar. At the free end of the bar the compressive stress pulse is reflected back into the bar as a tensile stress pulse. If the tensile strength of the bar is exceeded during this reflection process, a tensile fracture normal to the length of the bar is produced, and the broken end of the bar moves forward with a constant velocity equal to the average particle velocity trapped in the broken fragment. The new surface formed by the fracture becomes the new free end of the bar that reflects the remaining portion of the incident compressive stress pulse. This process is repeated any number of times until all of the incident stress pulse is reflected.

Jan 6, 1959

By Bennett Bates

A PAPER presented in South Africa' during 1925 by H. A. White gave a formula to express the efficiency of classification. The formula was originally developed by H. W. Newton of The Dorr Co. The derivation of this formula is as follows: Where E = Over-all efficiency of classifier Eu = Efficiency with respect to sand discharge Eo = Efficiency with respect to overflow I = Tons feed to classifier (input) 0 = Tons overflow U = Tons sands (underflow) i = Fraction of oversize in classifier feed o = Fraction of oversize in overflow u = Fraction of oversize in sands

Jan 5, 1927

By A. W. Schlechten, C. M. Hsiao

J. Pearson (British Iron and Steel Research Association, London, England)—Dr. Wagner has referred to the work of Richardson and Dancy and Gellner and Richardson on the reduction at 900°C of wustite films on iron. He has assumed that iron ions and electrons migrate backwards to the iron-wustite interface and that the reduced iron grows on the metal substrate. This would be a possible explanation of the results of these workers were it not for the fact that, as stated by Gellner and Richardson but not stressed, this growth in the center of the specimen can occur even

Jan 1, 1953

By AIME AIME

WHEN your good secretary was kind enough to ask me to speak tonight I was rather reluctant to do so lest it be just another case of a man who has been abroad inflicting himself on his friends. So if anybody wants to walk out on me it will be perfectly all right. In the matter of statistics, geography, geology, and the like, you can get more from an encyclopaedia than I can tell you. For that reason I want to restrict myself to mentioning just a few personal impressions of that great country, Australia. About ten days ago I met the professor of mining from the University of Adelaide. In our conversation, which ran into a discussion of the relative characterstics of the two countries, he asked me whether it was fair to think of Australia as a land of strikes and not think of the United States as the home of murderers, bootleggers, and gangsters. At any rate those are the things most prominently played up in the news from the respective countries, so you can see how distorted our conceptions can be.

Jan 1, 1931