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By Walter Rose

Theoretical expressions are presented to describe wetting and non-wetting phase relative premeability relations. These expressions have then been compared with existing published data, the conformance noted being sufficiently good to satisfy the requirements of some engineering use. As a consequence, it may be supposed that relative permeability characteristics of porous media now can be inferred from basic core analysis data, in a manner more convenient (although less direct) than presently available methods of experimental evaluation. INTRODUCTION This paper presents a new approach to the problem of relative permeability evaluation. A classification of published discussions of relative permeability concepts which have appeared in the petroleum literature will show that previously emphasis has been placed on methods of experimental measurement, on the interpretation of the data so obtained with respect to the variable properties of the system, and on theoretical and practical considerations which relate relative permeability to gross fluid behavior in petroleum reservoirs. Essentially, no detailed examination has appeared which treats the fundamental factors controlling the quantitative features of the relative permeability relation*, although cer- tain references can be Cited where a qualitative awareness of their existence and nature is indicated. This condition is explainable in terms of the recognized complexity of the problem, and in order to provide some basis for theoretical development, the general emphasis has been placed in the past on experimental procedures of evaluation, the validity of which, in principle, could be confirmed by the analysis of well and reservoir performance. However, because of the experimental difficulties which have been encountered (notably, difficulties due to the so-called "end effects"), and because of the general unreliability of field performance tests required to study the applicability of the data, relative permeability phenomena continue to be incompletely understood and described.? In this paper is examined the possibility of predicting relative permeabilities entirely from fundamental considerations. In addition, attention is called to certain important factors, previously unemphasized in the published literature, which now can serve as a basis for the eventual experimental confirmation of this and similar theoretical approaches, as well as the experimental solution of the problem in general. Therefore, the analysis presented herein has the dual purpose both of orienting future experimental activity and also of providing an immediate solution for the relative permeability porblem, sufficiently adequate for some engineering use. It will be seen that the conclusions reached are supported by theoretical and intuitive considerations, and they are not contradicted insofar as gross features are concerned by existing concepts and interpretations of published experimental data, except as specifically noted. Darcy's law, expressed simply as: k dp q = k/u dp/dx .......(1) where q is linear rate of flow (assumed horizontal), k is the † The poor comparison usually obtained between laboratory and field gas-oil ratios (c.f.. Fig. 4 of paper by L. E. Elkins) is illustrative of conditions which dimcourage unqualified acceptance of the results of previous studies except as presently useful approximations. In this connection, Evinger and Muskat have discussed in detail the discrepancy observed between field well productivity values and values obtained from the analysis of laboratory flow data.

Jan 1, 1949

By Walter Rose

Theoretical expressions are presented to describe wetting and non-wetting phase relative premeability relations. These expressions have then been compared with existing published data, the conformance noted being sufficiently good to satisfy the requirements of some engineering use. As a consequence, it may be supposed that relative permeability characteristics of porous media now can be inferred from basic core analysis data, in a manner more convenient (although less direct) than presently available methods of experimental evaluation. INTRODUCTION This paper presents a new approach to the problem of relative permeability evaluation. A classification of published discussions of relative permeability concepts which have appeared in the petroleum literature will show that previously emphasis has been placed on methods of experimental measurement, on the interpretation of the data so obtained with respect to the variable properties of the system, and on theoretical and practical considerations which relate relative permeability to gross fluid behavior in petroleum reservoirs. Essentially, no detailed examination has appeared which treats the fundamental factors controlling the quantitative features of the relative permeability relation*, although cer- tain references can be Cited where a qualitative awareness of their existence and nature is indicated. This condition is explainable in terms of the recognized complexity of the problem, and in order to provide some basis for theoretical development, the general emphasis has been placed in the past on experimental procedures of evaluation, the validity of which, in principle, could be confirmed by the analysis of well and reservoir performance. However, because of the experimental difficulties which have been encountered (notably, difficulties due to the so-called "end effects"), and because of the general unreliability of field performance tests required to study the applicability of the data, relative permeability phenomena continue to be incompletely understood and described.? In this paper is examined the possibility of predicting relative permeabilities entirely from fundamental considerations. In addition, attention is called to certain important factors, previously unemphasized in the published literature, which now can serve as a basis for the eventual experimental confirmation of this and similar theoretical approaches, as well as the experimental solution of the problem in general. Therefore, the analysis presented herein has the dual purpose both of orienting future experimental activity and also of providing an immediate solution for the relative permeability porblem, sufficiently adequate for some engineering use. It will be seen that the conclusions reached are supported by theoretical and intuitive considerations, and they are not contradicted insofar as gross features are concerned by existing concepts and interpretations of published experimental data, except as specifically noted. Darcy's law, expressed simply as: k dp q = k/u dp/dx .......(1) where q is linear rate of flow (assumed horizontal), k is the † The poor comparison usually obtained between laboratory and field gas-oil ratios (c.f.. Fig. 4 of paper by L. E. Elkins) is illustrative of conditions which dimcourage unqualified acceptance of the results of previous studies except as presently useful approximations. In this connection, Evinger and Muskat have discussed in detail the discrepancy observed between field well productivity values and values obtained from the analysis of laboratory flow data.

Jan 1, 1949

By W. N. Logan

WHAT is mineral wool? This question is frequently asked by those unacquainted with its manufacture. The word "mineral" suggests that it is of mineral origin; the word "wool" suggests that it is of animal origin; but the only similarities it has to wool are its fibrous character and its white fleecyness. Mineral wool is a fiber produced by melting rock to a glasslike condition and blowing the glass into fine white, wool-like threads. A -number of the products fabricated from-mineral wool are used for some form of insulation, but mineral wool is adaptable to many other uses. It is used in the manufacture-of pipe covering designed to with; stand the high temperatures produced in steam pipes. In a similar form of insulation it is used to cover boilers and furnaces. It is used in ,the fabrication of upholstery tow for sofas and car seats: In acoustics it has many uses, such as acoustifibroblock, which is used in floors to destroy sound and vibration, and acoustic mat, which is used under carpets to destroy sound. In the insulation of houses, loose wool and granulated wool are used beneath attic floors and between the studding in frame buildings to prevent the escape of heat in winter and the entrance of heat in summer. Mineral wool is used also in fabrication of linofelt, which is a quilted form of insulation; in fibrofelt, which is an insulating board; in the fabrication of lith, which is an insulating block; in anti-fibroblock ,which is used in insulation and refrigeration; in flexfelt; in loose wool; in pressed block; in heavy oiled wool; in dark oiled block; and for many other purposes. The materials used in the manufacture of mineral wool are of two kinds. The first is a rock which contains silt, clay and silica, with smaller amounts of lime and magnesia. The second is a more highly calcareous rock which may carry a small amount of magnesia. The latter is used as flux to assist in the melting of the former. The relative proportion of the alumina-iron-silica content to the lime-magnesia content is normally as fifty to fifty but a considerable range is possible.

Jan 1, 1932

LANS are underway for the annual meeting of AIME, to be held in New York, February 17 to 21. The technical program includes meetings of all divisions of all three branches, Mining, Metals, and Petroleum. The bulk of the technical sessions will be held at the Statler Hotel, and the annual banquet will be held at the Waldorf-Astoria, Wednesday evening, February 20. The technical program of the Mining Branch activities is included in this issue. While it is not complete in every detail, it shows general interest groupings as well as subjects to be discussed. The program for each division is shown separately to facilitate following the activities of these special interest groups. Then, after a full scale and possibly somewhat strenuous technical meeting, a post-meeting feature will appeal to many of the members. A restful cruise to Bermuda and Nassau is offered at special rates to AIME members and friends. The schedule is a 3:00 pm departure from New York on the Queen of Bermuda on Saturday, February 23; arrival at Bermuda at 7:00 am Monday, February 25; arrival at Nassau at noon, Wednesday, February 27; and the trip ending again in New York at 9:00 am, Saturday, March 1. Rates begin at $202.10 per person, with higher rates depending upon accomodations desired. The base rate includes outside room with private bath and all meals, as well as Federal, Bermuda and Nassau taxes. Reservations for the trip should be made immediately through Leon V. Arnold, 36 Washington Square West, New York 11, who is in charge of arrangements.

Jan 1, 1952

By F. V. Lenel, G. S. Ansell, E. C. Nelson

IRMANN'S' discovery that extrusions of fine alumi-num-flake powders possess remarkable high-temperature strengths has led to the production of a new class of engineering materials whose properties are derived from a fine dispersion of oxide particles in a metallic matrix. A fundamental study of such materials and elucidation of the mechanism whereby the oxide parti-

Jan 1, 1958

By Hertha Freche

THE diffusion of magnesium and silicon from the core into the high-purity coating of Alclad sheet is important commercially, and led to the use of a duplex product for the study of diffusion by means of spectro-graphic analysis of successive layers. It has been found that in the duplex materials the diffusion of magne-sium from an undersaturated aluminum-magnesium alloy into its high-purity aluminum coating is approximately of the same order of magnitude as the diffusion of silicon from a saturated aluminum-silicon alloy into its high-purity aluminum coating. However, if magnesium and silicon are both present in the alloy in the ratio of Mg2Si they appear to diffuse in the approximate ratio of this compound. Finally, if the alloy contains silicon in excess of the amount required by magnesium silicide, the amount of diffused silicon in the high-purity aluminum coating will also be in excess. The interdiffusion of metals in the solid state is of both scientific and technical interest, because it is helpful in the study of the alloy structure and in the solution of problems pertaining to the strength and surface condition of the fabricated product. W. C. Roberts-Austen1 carried out the first quantitative determination of the coefficient of diffusion of gold into lead. This classical experiment was followed by a series of investigations on the diffusion of metals and nonmetals in iron and steel and in nonferrous metals and alloys. Recently the diffusion of copper in coated strong aluminum alloys was investigated by A. Burkhardt2. This appeared to be the first published investigation on the diffusion of metals into aluminum.

Jan 1, 1936

By Daniel R. Hull

In 1926 Gendersl reviewed the existing theories of this subject and stated his views in support of the gas-pressure theory. Again, in 1937, the subject was thoroughly reviewed by N. B. Vaughan3 and by Phillips and Brick,2 so that no résumé is called for here. The purpose of this paper is to describe certain observations made in the course of mill work, and to point out that they mostly tend to confirm the gas theory of Genders. Vapor Segregation There is, however, one type of inverse segregation that can be accounted for by considering the volatility of one of the constituents of an alloy. The most familiar case is ordinary brass, which is subject to a zinc enrichment of a few tenths of a per cent at the surface of a chill casting. This has been noted in 70-30 brass by Genders, and a typical example of it is given in Table 1, which represents a cylindrical billet 7 in. in diameter by 55 in. long. After lathe-turning 1/32 in. from the surface, the remaining distance to the center was sampled at six equally spaced intervals. the lead, which is essentially the same throughout, will be mentioned later. Consider a brass-mill mold, either round or rectangular in cross section, standing several feet high. It may require a minute or two for pouring. Before it is full, the metal in the lower end has partly solidified and contracted somewhat away from the mold. The initial shell of solidification follows not far behind the top of the column, even if the central portion is liquid for a long way down. There is, then, a space between metal and mold that is filled with zinc vapor. The vapor has no exit, because the liquid at the top of the rising column is not only in contact with the mold but keeps UP a fresh supply of zinc vapor, which has, perhaps, already begun to condense in the lower portion. The cycle is short. Within a minute or two after the mold is full the bar has cooled enough to condense all the zinc. Some of it may condense on the mold; it might be expected that most of it would condense there, but the mold at that time is well coated with a velvety carbon residue from the oil dressing, overlain by fluffy zinc oxide that commenced covering the inside of the mold as soon as pouring began. The clean skin of the freshly cast brass offers a preferred surface for condensation. Reabsorption is quick and inevitable. A simple experiment indicates that a surprisingly large quantity of zinc vapor is trapped in the space between mold and

Jan 1, 1941

By Daniel R. Hull

In 1926 Gendersl reviewed the existing theories of this subject and stated his views in support of the gas-pressure theory. Again, in 1937, the subject was thoroughly reviewed by N. B. Vaughan3 and by Phillips and Brick,2 so that no résumé is called for here. The purpose of this paper is to describe certain observations made in the course of mill work, and to point out that they mostly tend to confirm the gas theory of Genders. Vapor Segregation There is, however, one type of inverse segregation that can be accounted for by considering the volatility of one of the constituents of an alloy. The most familiar case is ordinary brass, which is subject to a zinc enrichment of a few tenths of a per cent at the surface of a chill casting. This has been noted in 70-30 brass by Genders, and a typical example of it is given in Table 1, which represents a cylindrical billet 7 in. in diameter by 55 in. long. After lathe-turning 1/32 in. from the surface, the remaining distance to the center was sampled at six equally spaced intervals. the lead, which is essentially the same throughout, will be mentioned later. Consider a brass-mill mold, either round or rectangular in cross section, standing several feet high. It may require a minute or two for pouring. Before it is full, the metal in the lower end has partly solidified and contracted somewhat away from the mold. The initial shell of solidification follows not far behind the top of the column, even if the central portion is liquid for a long way down. There is, then, a space between metal and mold that is filled with zinc vapor. The vapor has no exit, because the liquid at the top of the rising column is not only in contact with the mold but keeps UP a fresh supply of zinc vapor, which has, perhaps, already begun to condense in the lower portion. The cycle is short. Within a minute or two after the mold is full the bar has cooled enough to condense all the zinc. Some of it may condense on the mold; it might be expected that most of it would condense there, but the mold at that time is well coated with a velvety carbon residue from the oil dressing, overlain by fluffy zinc oxide that commenced covering the inside of the mold as soon as pouring began. The clean skin of the freshly cast brass offers a preferred surface for condensation. Reabsorption is quick and inevitable. A simple experiment indicates that a surprisingly large quantity of zinc vapor is trapped in the space between mold and

Jan 1, 1941

By S. R. du Toit, W. J. Oberholzer, M. I. Watson, D. G. Krige

The objectives, essential features and implications of the 'random' and 'deterministic' types of ore value surfaces are examined as well as the basic requirements for a satisfactory prediction model. The 'random' method used on the South African gold mines and based on observed auto-covariance patterns is briefly discussed as well as its justification in preference to the 'deterministic' approach. Various mathematical models for auto-covariance patterns are examined for the one-dimensional case. It is also shown that these patterns as estimated for ore values in certain mines agree closely for various sizes of ore unit. In two case studies the variations in gold, uranium and ore thickness covariance patterns are examined and compared with certain geological features established independently from sedimentological studies.

Jan 1, 1969

By Roswell H. Johnson

What becomes of the water which must have filled the oil and gas sands at the time of deposition, has long puzzled students of oil and gas and has found expression in Munn's well-known article on the hydraulic theory. Both Munn and Clapp have pointed out that in the Appalachian field the deeper sands carry increasingly less proportionate amounts of water. It seems to me probable that the principal source of oil and gas has been in the shales in proximity to the sands which now contain these products. The sand spits which mark off the lagoons from the sea comply particularly with the requirements of a limited sand imbedded in shales rich in organic matter. Cunningham Craig has objected to this view that the rich organic muds of lagoons are found only at the surface. That such muds do extend to considerable depth 1 am assured by Prof. Douglas W. Johnson, who has made an extensive study of the Atlantic Coast marshes. As any particular sand body becomes weighted by a heavier and heavier overburden, the result of increasing deposition, a part of the very large percentage of water in the uncompacted sand and mud is forced out. The water percentage of freshly settled mud is vastly higher than that of the resultant shales, or even of a very porous sand. If beds of less compressible material meet or underlie the shales in question, there will frequently be a lateral motion along such beds to some point where the upward movement will be resumed. We find in our laboratory work here that oil, gas, and water have extremely slight capacity for gravitational sorting while in a state of rest, but when moving the gravitational sorting is readily accomplished. As the oil, gas, and water pass a body of larger pores, the gas, owing to its lack of capillary attraction, is retained in the large pores. This has been predicted by Washburne, Blatehley and others on the ground that the water has a higher capillarity and grips the finer pores in such a way that there will be a greater proportion of oil and gas in the large

Jan 1, 1915

By W. B. McCarter

Broadly speaking, the year 1934, one of the most active in the history of the Coast, has been both disappointing and revealing. Of the 18 new oil-producing areas, only two have shown the qualities of a first class oil field. Many of the new areas are discouraging for the horizons exploited, because of close association of gas and salt water, and the absence of any appreciable oil zone. In spite of amply fulfilling the expectations of drilling and geophysical development, the year has fallen far short of the results that normally should be expected from such a campaign. In 1934, the Cockfield zone has been disappointing because its exploration down the dip from the Conroe and Tom Ball fields revealed only such distillate fields as Splendora, Eureka, and the great gas-sand thickness at Katy. The zone proved good at Raccoon Bend. Newer Oligocene and Frio fields in Texas, with the exception of Hastings, were also disappointing, as Van Vleck arid Old Ocean attest. The discovery at Dickinson is not startling. The development of Hastings, Tom Ball, Dickinson and the deep zone at Raccoon Bend will be slow. A new strip of prospective territory of minor importance lying inland from the Conroe trend was opened by the Kittrell discovery. During the year 206 unproductive wildcats were drilled on the Texas Coast, compared with 207 during 1933 and 141 during 1932. During 1934, there were 835 oil and gas wells and 229 dry holes drilled in proved fields, in contrast with 1100 in 1933 and 512 in 1932. The past year's production was actually 60,868,260 bbl., or 2,020,764 bbl. less than in 1933. The present annual rate of Texas Gulf Coast production is about 61 million barrels per year. The daily Texas Coast production decreased 5537 bbl., or 3.2 per cent, during the year. The total daily production at the end of the year was 173,598 bbl. Eighteen wildcats opened up new oil and gas pools during 1934, so that there are now 78 active pools and 3753 producing oil wells. The production of the average well is 45 bbl. per day. The price of crude oil was almost uniform in 1934,

Jan 1, 1935

By James G. Crawford

Correlation Of water with its reservoir zone or formation has been one of the applications of oil-field water analysis of greatest direct value to the petroleum engineer. The water in each producing zone tends to have diagnostic characteristics by which it can be distinguished from every other water above or below that zone in that immediate vicinity. Representative analyses of oil-field waters from producing oil and gas fields in the Rocky Mountain region are included, and the diagnostic characteristics are discussed briefly. It is concluded that the generally dilute nature of Rocky Mountain oilfield waters is a result of dilution by meteoric waters, and that there is no relationship between presence or absence of commercial oil and the character of water in a structure. Introduction The study of waters associated With oil and gas began more than 50 years ago and has been well recognized by operators, engineers, and geologists for about 30 years. It appears unnecessary at this time to recite the history of oil-field water analysis; suffice to say that it has proved its worth many times to the production engineer suddenly confronted with water problems in producing oil and gas wells. Chemists and geologists have studied the possible origin of these waters and as Yet the subject is unsolved in many important phases. There are both local and regional problems connected with the explanation of concentrations and character- istics peculiar to each field, each subsurface zone and each province. Criteria useful in postulating the Occurrence of oil Or gas in One province completely fail when applied to another, and data carefully prepared and analyzed from one field may be actually misleading when applied to another. Correlation of water with its reservoir zone or formation has been one of the applications of oil-field water analysis of greatest direct value to the engineer. The concentrations and characteristics of the waters are essential to the engineers and geologists making interpretations of electric logs in this region. The behavior of water under conditions of reservoir temperature and pressure is dependent to a great degree upon its concentration and characteristics, and thus important to the reservoir engineer. With the advent of secondary recovery methods in the Rocky Mountain region the characteristics and treatment of water will become increasingly important. Premises upon which Correlation Is Based A brief review of the geochemical history of oil-field waters will suffice to present the premises upon which correlations of the waters are based. Sedimentary rocks which are now stratified were first sediments in seas, lakes and streams. These sediments were filled interstitially with connate water. With burial the sediments were compressed arid consolidated, integrated and indurated into bed rock and much of the connate water was dispelled. Following the formation of bed rock the strata were sub-

Jan 1, 1949

Equilibrium in Lead Smelting. By S FREDERICK RAVITZ AND KENNETH E FISHER (Tech Pub 681, also Trans , vol 121 2300 words) Four liquids are ordinarily produced in lead smelting, namely, bullion, speiss, matte and slag To determine whether these exist together in equilibrium, the distribution of gold and silver among them was measured To crucibles containing similar mixtures of all four products, varying amounts of silver were added, and the crucibles were heated together under the same conditions for 3 hr, during which the charges melted and separated into four layers After cooling, these layers were assayed for silver, and the distribution coefficients, 1 e , the ratios of the concentration of silver in any particular layer to that in the bullion, were calculated In each experiment, each distribution coefficient was found to be constant, regardless of the amount of silver used Similar results were obtained using gold instead of silver The constancy of the distribution coefficients indicates that the bullion, speiss, matte, and slag exist together in equilibrium

Jan 1, 1937

By M. M. Fine

Normally the U. S. produces less than 10 pct of its annual manganese requirement. About 95 pct of domestic consumption is used by the steel industry.1 The strategic and critical nature of manganese has been recognized by its inclusion in the national stockpile and by intensified research directed toward cataloging and evaluating domestic manganiferous deposits. The USBM has participated in these activities for many years with field and laboratory studies to assess the extent and potential utilization of domestic manganese ores. One area of particular interest is in the vinicity of Batesville, Ark., where deposits have been mined since 1849 for both manganese and ferruginous manganese ores. Production is centered in Independence County, but deposits are also found in Sharp, Izard, and Stone counties in north- central Arkansas. Miser has described the geology and manganese mineralization in some detail.2,3 The rocks of the area are sedimentary, consisting of sandstone, limestone, shale, and chert. The two formations of greatest importance,4 Fernvale lime- stone and Cason shale, are host rocks of the primary manganese mineralization.

Jan 8, 1959

By Waldemar Lindgren

The following pages present data accepted by many geochemists and geologists regarding the succession of minerals and the temperatures of formation in ore deposits affiliated with igneous rocks. They also present the individual views of the author on the composition of the solutions that were active and on the mode of deposition. He does not regard these views as speculations or hypotheses but as forming a well motivated and consistent theory. It is not certain, however, that all investigators will subscribe to them. Introduction The mining engineer may not always be interested in the field of stability and temperature of origin in the mineralogy of ore deposits, but he certainly is interested in the succession of minerals because this has a definite bearing on the understanding of the ores and on the best processes of extraction. It is proposed, therefore, to summarize in plain language the principal features of succession as shown in metallic ores. Chemical analyses of ores are always important, but the real knowledge of succession—sometimes called paragenesis-—of ores has been gained only in the last 20 years, by the study of polished sections. The study of hand specimens threw much light on the subject—as shown, for instance, by Breithaupt, whose "Paragenesis," written a hundred years ago, is still useful—but the results have been modified by our slowly gained understanding of the processes of replacement. Indications of Temperature Melting Points.—In the first place, a distinction must be made as to whether the ore is a product of magmatic consolidation, of pegmatitiza-tion or of hydrothermal activity. Most of the ores fall in the latter class. In any case, the melting points, although of importance, are not definite indications. In a magma the oxides and sulfides are likely to be among the earliest crystalline products (magnetite, ilmenite, zircon, corundum,

Jan 1, 1937

By M. R. Geer, H. F. Yancey

Although the use of dense suspensions for coal cleaning was pioneered in the United States with the Chance sand flotation process, and during the past year a pilot plant using a magnetite suspension has started operation in this country, the more recent developments in this field of coal cleaning have occurred principally in the Netherlands. During the thirties the Dutch developed the Barvoys process, in which a medium of barite and clay is employed, the Tromp process, which utilizes a magnetite suspension, and the Loess process, in which is used the air-borne earth or soil known as loess.1-3 All these processes are finding increasing use in European coal-cleaning practice. Now a fourth process, the cyclone cleaner, is under development by the Netherlands State Mines. A cyclone thickener for reclaiming and thickening the dense suspension is a novel feature of the Loess process. Through accident, the discovery was made that the cyclone could be utilized as a cleaning device for fine coal. When the cyclone thickener at the Maurits mine plugged, the overflow was found filled with clean coal free of refuse, and from this observation developed the concept of the cyclone as a coal cleaner. In June 1945 the cyclone cleaner was observed by one of the authors,' and in September 1945 it was described by Dries-sen6 in a paper presented in London before the Institute of Fuel. As the cyclone seemed to offer unusual promise as a means of extending heavy-medium cleaning to the finer sizes of coal that cannot readily be treated in existing heavy-medium processes, the Bureau of Mines, following Driessen's, presentation, launched an investigation of the cyclone as a coal cleaner. Added impetus was given to this study by the present increased interest in heavy-medium cleaning in this country. Object and Scope of Investigation Driessen's report, although comprehensive in many respects, did not include a detailed description of the cyclone cleaner, and contained almost no information on the influence of the various operating variables of the cyclone. It was necessary, therefore, to investigate the influence of the cyclone adjustments on its performance before studying the application of the cyclone to various coal-washing problems. The present report is confined entirely to these preliminary tests, designed to demonstrate the operating characteristics of the cyclone. The investigation has been in progress

Jan 1, 1949

By E. Hoek

INTRODUCTION Rock slope stability research has been in progress for the past four years at the Royal School of Mines in London under the sponsorship of a consortium of 23 companies* with interests in open pit mining. This paper reviews the principal aims and achievements of this research project. In order to assist the reader in following these details, the basic philosophy underlying the formulation and direction of this research project is discussed. DISTRIBUTION OF RESPONSIBILITY In open pit mining, the economic necessity of keeping waste rock removal to a minimum generally means that the mine slopes have to be excavated to the steepest possible slope angle. On the other hand, excessive steepening of these slopes can induce failures, which may negate the economic benefits that have been aimed at and which may also result in loss of life and damage to equipment. Consequently, where slope failures are likely to prove to be a problem, an evaluation of the stability of the slopes to be created should be included as part of the overall pit design. How is the stability of a rock slope evaluated? When this question was examined, during discussions on the research policy to be followed at the Royal School of Mines, it was clear that relatively few satisfactory techniques were available in a form that would be comprehensible and therefore useful to the practical mining engineer. It was recognised that the research project must be directed towards two distinct aims: a) The evaluation of existing techniques for rock slope stability analysis and the provision of new techniques where these existing methods were found to be inadequate and b) The presentation of the results of this evaluation and research in a form that would be useful to engineers without specialist training in rock mechanics. It was soon realized that a university based research team, however large and efficient, could not achieve these aims without the co-operation and assistance of mining engineers,

Jan 1, 1972

By B. Chalmers, Stefan Wojciechowski

Rotary oscillation of the mold has been used to produce mechanical stirring of the melt during unidirectional solidification. Al-Cu alloys (1 to 4 wt pct Cu) were solidified to study the influence of alloy composition, temperature at which intensive cooling was initiated, and intensity of stirring on the temperature distribution in the sample, the resulting structure, and the copper microsegregation at the columnar to equiaxed transition. The Proposed explanation for the equiaxed solidification in stirred castings consists of the melting off of dendrite fragments, their partial remelting in hotter liquid, and the subsequent growth of the surviving part when the temperature of the melt is lowered. This may result in the formation of a crystal network, which can stop the growth of the columnar crystals and produce the equiaxed zone. It has long been known and many times affirmed that ultrasonic vibrations or relative motion of liquid and solid can significantly reduce the length of the columnar zone and refine the grains in the equiaxed zone in ingots and castings. Because of the technological importance of these phenomena many investigations have been conducted in which ultrasonic energy or mechanical vibration,1-6 electromagnetic stirring,7"10'17 magnetic stirring,"'12 or mechanical stirring13'14 were used to produce the relative liquid-solid motion. More recently, the question of the importance of natural (or thermal) convection has been raised.15-l7 Several possible mechanisms have been suggested.l,8,18-20 They can be divided into two main groups. The first group includes such nucleation hypotheses as nucleation frequency enhancement due to cavitation at the mold wall or other surfaces; cavita-tion in the body of the liquid resulting from the pressure wave, or an agglomeration mechanism, which involves the formation of nuclei by the accretion of subcritical nuclei. The second group considers the grain-refining action to be due to crystal multiplication phenomena such as the removal of the dendrite fragments by viscous forces or by a high-pressure cycle following cavitation or by a melting-off process. Sbme recent investigations give good experimental support to the melting-off proposa1.21-23 The purpose of the present study was to examine the effect of mechanical stirring during the unidirectional solidification on the structure of alloy samples and on the solidification variables. The motion of the liquid was produced by rotary oscillation of the mold around its vertical axis.

Jan 1, 1969

By R. C. Temps, G. E. Aiken

Compania de Acero del Pacifico, S.A., the sole Chilean steel producer, is adding to the expanding Chilean economy with development of the El Algarrobo mine. Expected to go on stream early in 1962, Algarrobo is a conventional open pit mine that will include facilities for ore extraction, crushing and screening, rail transport to the harbor at Huasco, modern ship-loading equipment and maintenance shops. CAP anticipates producing 1.38 mil- lion tons annually of high-grade ore for national and world market consumption. Chilean and North American management and engineering teams combined more than a decade ago in the financing and building of CAP'S Huachipato integrated steel plant. A similar performance is being achieved in northern Chile near the town of Vallenar with the opening of a 50-year supply of iron ore from the Algarrobo deposit. This successful intra-American undertaking deserves special mention in these times when some U.S. foreign assistance programs must be defended, particularly with respect to Latin America. North American financial participation in Algarrobo, through the Export-Import Bank of Washington, represents the greatest portion of the $24 million being invested.

Jan 3, 1962

By R. E. Reed-Hill, W. H. Hartt

The "(3034) " twin lamellae in magnesium have been reexamined using electron microscope replicas. The double twinning sequence (1011)- (1012) for these lamellae has been reconfirmed. Evidence is presented showing that the irrational habit of these twins is probably the direct result of a need to accommodate the second-order twinning shear. This accommodation vesults in both an external shear in the matrix and an internal shear in the lamella. A model is presented which accounts for the experimental obseruations. HCP metals are generally characterized by strong textures in which the basal planes of the grains tend to be aligned parallel to the rolling direction in sheet or plate and to the axis of wires and rods. Since these directions are normally those in which finished products may be subjected to uniaxial tensile stress, these textures effectively place the crystals of magnesium objects in orientations unfavorable to both basal slip and {1012) twinning, the easily activated deformation systems of this metal. However, when magnesium crystals are deformed near room temperature by a tensile stress nearly parallel to the basal plane, another mode of deformation can occur.',2 This is _a double twin which forms first by twinning on {loll), followed by retwinning on (1012). The resulting twin lamellae are of considerable interest. First, they can be responsible for "brittle fracture''; when a tensile stress axis lies in the basal plane, because the reoriented crystal structure of a lamella is well-aligned for slip while the parent crystal is not. Extensive internal deformation may thus occur while the matrix is still almost undeformed. This deformation can produce a ductile rupture running the length of the twin.3 Complete failure of the specimen may then oc-cure by the spreading of cracks from one twin lamella to another, or by the movement of a crack into a grain boundary and then along grain boundaries. Since the the volume fraction of these doubly twinned elements is normally very small, the fracture may be classed as brittle, although the fracture mechanism is, of itself, essentially ductile. It is quite probable that the ductility transition, normally observed4 in magnesium at or slightly Obove room temperature, is closely associated with these second-order twins. The detailed relationship of these twins to fracture in single crystals will be the topic of another paper. The present paper is concerned with a second important aspect: the irrational habit of these double twins that falls close to {3034), or approximately 7 deg away from the primary (10il) twin habit. There is good reason to believe that this habit results directly

Jan 1, 1968