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By D. R. Hay, E. Scala

Electrotransport has been superimposed on the rate-limiling- step in zone refining which is the impurity diffusion through the liquid at the solid/liquid interface. The efficiency of zone refining is increased and relative resistivity ratios (P300°k/P4 2°K) he increased by 50 pel in tungsten for a given number of posses using- the electrotransport field-aided method. The effiect of zotze refining in the presence of an electric field on the relative resistivity ratio is examined as a function of its intensity and polarity. THE effect of electrodiffusion on the effective distribution coefficient of zone refining has been discussed by Pfann and Wagner.' Control of the distribution coefficient in zone refining is of twofold interest. A distribution coefficient of unity can be increased or decreased, making possible the transfer of some previously inseparable solutes. The general efficiency of zone refining can also be increased. In the conventional zone-refining process impurities are removed by their retention in the molten zone and subsequent deposition at the end of the rod after a complete passage of the zone. In higher-melting-point systems a second mechanism may also operate, the volatilization of impurities from the molten zone. It has been suggested by schadler2 that, in refractory metals, vacuum distillation plays the predominant role in purification. In Koo's results,3 the resistivity ratio decreased beyond a zone-refined length of 6 in. from the starting end, indicating that some purification does in fact occur by true zone-refining action. Hay and scala4 showed that the degree of purity as measured by the relative resistivity ratio method depends on the square root of time in the molten zone (number of passes) and thus appears to be limited by diffusion in the boundary layer at the solidifying interface assuming good mixing in the body of the molten zone where a linear rate would prevail. The final concentration of impurities in electron-beam floating-zone purification depends very much on the operating conditions and results obtained by various investigators2,3,5 are difficult to correlate. The diameter of the starting material, operating vacuum, and rate of traverse are among the factors to be considered. There are, nevertheless, some general observations to be obtained from the literature. Lawley5 reviewed the literature up to 1962 and concluded that the major contaminants generally remaining in tungsten after electron-beam zone refining are molybdenum and carbon. Molybdenum due to its high melting point and distribution coefficient of nearly unity would be expected to be difficult to remove by either volatilization or zone refining. Carbon is not only a common contaminant in vacuum systems, but is also very difficult to remove by conventional vacuum melting. even with vacuums of 10-7 mm Hg. For each of those impurities removed by zone refining the equation of Pfann and Wagner may be applied: It relates the effective distribution coefficient k to a superimposed driving force which accelerates the solute away from the interface with a terminal velocity L" and to the more conventional zone-refining parameters; v = rate of traverse, t = thickness of the diffusion layer at the solidifying interface, D = diffusivity of the solute in the molten zone, and ko = equilibrium distribution coefficient of the impurity.

Jan 1, 1965

By Roy J. Greenfield, Charles H. Stoyer

A geophysical survey was made in Kylertown, Pa., in an area where the ground water is polluted with acid mine drainage. Since acid mine water is a good electrical conductor, both direct-current electrical and electromagnetic loop methods were examined for their ability to determine the subsurface electrical conductivity structure and from this to imply the location of the acid water. Consistent results were obtained with the two methods and the interpreted subsurface resistivities were consistent with the electrical resistivity measured for water samples. It was demonstrated that fracture traces which act as conduits for ground water flow can be located with electromagnetic surveying methods. Thus geophysical methods for measuring subsurface electtrical resistivity can be used to advantage for monitoring the environmental impact on the ground-water system of acid mine water.

Jan 1, 1977

By John Gross

THE deductions drawn in crushing and grinding operations have heretofore been based on a separation of the products into various sizes. A crushed product may be sized by sieving, by elutriation, and by aid of the microscope. To estimate the surface of each size the relation of the surface to the estimated average diameter must be assumed. Such a relation, owing to the irregularity of the particles, may involve two assumptions: First, a factor to convert average diameter to surface for one particular size; and second, a variation in the factor as the diameter of the particle changes. Obviously a surface measurement in which such assumptions and estimates are involved is questionable. In the first paper of this series1 a method has been given by which an accurate measure of surface of quartz can be obtained from its dissolution rate. By the use of this method, surface measurements have been made on a series of sieve sizes of crushed quartz, the results of which are given and discussed in this paper.

Jan 1, 1928

By F. H. Gilpin

SINCE Noah pitched his ark within and without with pitch, the use of asphalt in human endeavor has been increasing-for Noah's pitch was asphalt. Asphalt is a bituminous material found in nature, either pure or admixed with smaller or greater quanti-ties of mineral and non-mineral materials, or obtained by the refining of crude asphaltic-base petroleum under proper methods of control. Native or "natural" asphalts are scattered through-out the world, though the commercial value of the various deposits varies greatly, depending upon both their accessibility and magnitude and the quality of the material found. It is an acknowledged fact that such asphalts have been produced through natural causes by practically the same application of tempera-ture and pressure as are used in the modern refining of crude asphaltic-base petroleum. The best known of all the native asphalt deposits are those of Trinidad Lake in the Island of Trinidad, British West Indies, and of Bermudez Lake in Vene-zuela. Asphalt from Trinidad Lake, after refining to remove organic and some inorganic diluents, contains approximately 35 per cent, of inorganic residue, and the asphalt thus produced must be fluxed with lighter asphaltic or semi-asphaltic base oil to make it com-mercially utilizable. The refined asphalt obtained from the Bermudez Lake deposit contains from 4 to 6 per cent. of inorganic material which cannot be removed. This asphalt, also, must be fluxed to produce com-mercial products. Small quantities of similar materials are available in other locations. The best pure native asphalt' is known as. gilsonite and is mined in com-mercial quantities in the State of Utah. In numerous places in the United States, particularly Oklahoma and Kentucky, there are deposits of sand¬stone and limestone impregnated with bitumen, which are known as rock asphalts. These rock asphalts may be used, particularly in the paving industry, either as found or by slight fluxing; from some deposits the asphalt is extracted and marketed commercially.

Jan 2, 1923

POSITIONS VACANT The National Bureau of Standards needs men to fill metallurgical positions with salaries varying from $1200 to $2000, depending upon the training and experience of the candidate. Experience either in ferrous. or, non-ferrous metallurgy. Duties will be almost entirely of an investigational nature, in connection with problems of military importance. Qualified men are urged to send to the Bureau of Standards at once a statement of training and experience, names of references, acid minimum salary that would be accepted, so that they may he advised of appropriate civil service examination for which to file papers. Until further notice, such papers are received by the Civil Service Commission at any time and ratted promptly.

Jan 10, 1917

By Newell G. Alford

Forecasts of future timber consumption in soft-coal mining are handicapped by the lack of adequate experience records for estimating properly the timber requirements of the industry. Data were obtained from plants where records are kept or from operators who collected the information and to these were added composite figures for the continental United States in 1905 and 19191 and for central and western Pennsylvania and for Illinois in 1922.2 The result, representing slightly over 928,000,000 net tons, is shown in Table 1. Some of the companies furnishing data were unable to segregate the timber into classes of use but for those who did, Table 2 shows the board feet of posts and cross ban used per ton of coal mined and the percentage of the total timber consumed that was used in roof support. The wide variation in amounts of timber per ton of coal mined is the result of

Jan 1, 1924

By J. K. Kerver, J. S. Osoba, J. G. Richardson, J. A. Hafford

A detailed study of a number of methods of relative permea-abilitv measurement has been made in a search for the tech-niqrle most suited to routine analysis of cores taken from reservoir rock. It has been found from tests run on the same samples of core material by a number of techniques that the Penn State, Hassler, Hafford, and dispersed feed techniques all yield results which are felt to be reliable. Conditions under which the faster single core dynamic technique may be used are described. Further work on the calculation of relative permeabilities to oil from data obtained by the gas drive method is needed before this latter rapid method can be utilized. Correlations between theoretical studies and experimental results have been obtained in studies of the boundary effect. pressure distribution in two-phase flow, and gas expansion effects. Previous conclusions that the effects of the outflow boundary could be made negligibly small have been substantiated. Results of experimentally determined oil and gas pressure distributions along a core sample during flow are presented. Further studies of the effects of rate of flow in the measurement of relative permeability-saturation relations have shown that results are independent of the rate of flow as long as the flow rate is below the point where inertial effects commence. An analysis of the effects of a severalfold expansion of gas along the flow path indicates that while saturation gradients are induced in the test sample, the errors caused by this phenomenon in relative permeability measurements are small. INTRODUCTION Many pages of literature have been devoted to pointing out the need for relative permeability-saturation relations in reservoir engineering. One of the most attractive ways of obtaining this information is by the analysis of samples of core material taken from the formation in question, and again literature has described man); methods for obtaining these data. It is the purpose of this paper to present the work that has been done in the study of some of these published methods together with some other methods that have been recently developed in this laboratory. Also, a study of some of the factors that influence the laburatory determination of relative permeability-saturation relations is presented. FACTORS WHICH AFFECT LABORATORY STUDY OF FLUID FLOW THROUGH RESERVOIR ROCK To determine relative permeability-saturation relations of samples of reservoir rock in the laboratory, it is important to know what factors affect these measurements in order that the magnitude of these effects can be ascertained and steps then can be taken to eliminate or, in some cases, to minimize them. The factors that have been investigated are the boundary effect, the effect of gas expansion. and the rate effect. Boundary Effect In laboratory experiments in which two immiscible fluids are flowed through a porous medium, there exists a discontinuity of capillary properties at the outflow face. This discontinuity exists became the fluids pass from a region of finite capillary pressure in the sample to a region of zero capillary pressure in an open receiving vessel. The capillary forces existing in the core caupe the rock to tend to retain

Jan 1, 1952

By J. J. Kramer, G. W. Wiener, K. Foster

The effects of the primary grain size and sheet thickness on the secondary growth rates of grains with (100) surface planes were studied in 3 pct Si-Fe sheets. This secondary grain growth was carried out under conditions in which the {100} plane had the lowest surface free energy. The value of the surface energy difference, between the (100) plane and the random matrix planes was found to he only about 3 pct of the grain boundary energy, indicating that most of the driving force for secondary growth is supplzed by grain boundary energy. A method for obtaining cube texture in 3 pct Si-Fe sheets by a secondary recrystallization process has been reported.' It has been demonstrated that a difference in surface free energy between the (100) plane and other planes is responsible for this growth, where the (100) plane has the lowest surface energy. A semiquantitative relation has been derived for secondary grain growth in sheets where primary grain growth has proceeded until the grains have grown through the sheet and the average grain diameter in the plane of the sheet is from one to two times the sheet thickness. Then, the linear growth rate, G, for the secondary grains can be given by where M is the grain boundary mobility, is the grain boundary free energy, is the average primary grain radius, A is the average difference in surface free energy between the (100) plane and planes of other orientations, t is the sheet thickness, and C is a term first proposed by zener6 which acts as a negative driving force, the effect of inclusions in holding up grain boundary motion. Since the problem of grain growth being discussed is under conditions where the matrix grain size is at least equal to the sheet thickness, the radius r is, of course, a function of the sheet thickness. The term B/r is the grain boundary driving force normally associated with inclusion inhibited or texture inhibited secondary recrystallization. Here, however, the term is modified to account for the fact that growth occurs in thin sheets. The term is the additional driving force available because of the difference in surface free energy. The purpose of the present work has been to evaluate the driving force terms of the growth equation by studying growth rates of (100) secondary grains as a function of sheet thickness and primary grain size. From these data it has been possible to determine the relative values of grain boundary energy, surface energy difference, and the inclusion term, C. EXPERIMENTAL PROCEDURE A 3 pct Si-Fe alloy was melted and cast under a helium atmosphere using electrolytic iron and a pure commercial grade of silicon as raw materials. The alloy was hot and cold rolled to a thickness of 0.6 mm, and samples approximately 5 in. long by 1 1/4 in. wide were cut from the cold-rolled sheets. Four different primary grain sizes were obtained

Jan 1, 1963

By A. G. Paithankar, G. B. Misra

Although certain physical mechanical properties of rocks have been claimed to give an estimate of penetration rate in percussive drilling, the authors' work shows that the correlation of penetration rate with individual rock properties is Poor. The authors have developed a good correlation between penetration rate and a set of rock properties but the relation is complex. Energy per unit volume has been used as a measure of penetration rate in percussive drilling by Hustrulid and Fairhurst; however, their test setup is large wing a full size drill bit. The authors determined the minimum energy for unit volume Ev min for any rock at the optimum index angle in a simple laboratory drop tester wing a sharp microbit with a tip angle of ll0°. This Ev min has been found to correlate well with penetration rate obtained in controlled laboratory drilling in different rocks for different stages of bit wear. A comprehensive relation has been developed between penetration rate and Ev min.

Jan 1, 1981

By O. F. Thornton, D. L. Marshall

Results of the determination of the inter stitial water content of several core samples from oil reservoirs are presented. Data obtained by the capillary pressure method, which has recently been developed, are compared with water saturations measured in cores cut with oil-base mud and with values calculated from the electrical resistivity of the formation. The agreement between the capillary pressure and other methods, combined with the fact that similar agreement has been obtained by others, indicates that the capillary method properly applied yields results sufficiently accurate for most engineering purposes. In some cases, it may be possible to extend the utility of data obtained with the capillary pressure method by correlation of interstitial water saturation with more easily measured physical properties of the media. Introduction Several methods are in use for determining or for estimating the interstitial water saturation at given points within oil and gas reservoirs. The direct measurement of the water content of cores obtained with nonaqueous fluid in the hole is believed to be an accurate method under most conditions. The water saturation may be calculated by use of the resistivity curves of the electric log,' although this method is not applicable under conditions that exist in some reservoirs. Recently, a method has been developed and described3.' wherein the interstitial water saturation of cores is measured at a capillary pressure such that conditions existing in the reservoir are simulated. The purpose of this paper is to present data obtained by use of this latter method, and to compare the results obtained with determinations made by other means. Method The theory underlying the capillary pressure method applied to petroleum reservoirs has been discussed adequately in the literature by Garrison,2 Leverett,5 and Others.3,6,7 Briefly, and simply, capillary pressure is defined as the difference in pressure between two contacting fluid phases, such as oil and water. For the simplified sand, water and oil system illustrated in Fig I, the pressure difference can be stated as follows:6 where Pc is the capillary pressure in pounds per square inch, ? is the interfacial tension between oil and water in pounds per inch, r1 and r2 are the radii of curvature of the interface between oil and water in inches. Capillary pressure varies in a given reservoir with depth because of the greater density of the water phase as compared with oil or gas. The following equation expresses the difference in pressure between two points: p1- p2 - h?p/144 [2] where p1 — p2 is the capillary pressure difference in pounds per square inch, h is

Jan 1, 1947

By D. L. Marshall, O. F. Thornton

Results of the determination of the inter stitial water content of several core samples from oil reservoirs are presented. Data obtained by the capillary pressure method, which has recently been developed, are compared with water saturations measured in cores cut with oil-base mud and with values calculated from the electrical resistivity of the formation. The agreement between the capillary pressure and other methods, combined with the fact that similar agreement has been obtained by others, indicates that the capillary method properly applied yields results sufficiently accurate for most engineering purposes. In some cases, it may be possible to extend the utility of data obtained with the capillary pressure method by correlation of interstitial water saturation with more easily measured physical properties of the media. Introduction Several methods are in use for determining or for estimating the interstitial water saturation at given points within oil and gas reservoirs. The direct measurement of the water content of cores obtained with nonaqueous fluid in the hole is believed to be an accurate method under most conditions. The water saturation may be calculated by use of the resistivity curves of the electric log,' although this method is not applicable under conditions that exist in some reservoirs. Recently, a method has been developed and described3.' wherein the interstitial water saturation of cores is measured at a capillary pressure such that conditions existing in the reservoir are simulated. The purpose of this paper is to present data obtained by use of this latter method, and to compare the results obtained with determinations made by other means. Method The theory underlying the capillary pressure method applied to petroleum reservoirs has been discussed adequately in the literature by Garrison,2 Leverett,5 and Others.3,6,7 Briefly, and simply, capillary pressure is defined as the difference in pressure between two contacting fluid phases, such as oil and water. For the simplified sand, water and oil system illustrated in Fig I, the pressure difference can be stated as follows:6 where Pc is the capillary pressure in pounds per square inch, ? is the interfacial tension between oil and water in pounds per inch, r1 and r2 are the radii of curvature of the interface between oil and water in inches. Capillary pressure varies in a given reservoir with depth because of the greater density of the water phase as compared with oil or gas. The following equation expresses the difference in pressure between two points: p1- p2 - h?p/144 [2] where p1 — p2 is the capillary pressure difference in pounds per square inch, h is

Jan 1, 1947

By E. W. Enqelmann

DURING January, 1933, burlap or coco matting was placed in the bottom of launders handling various products of the flotation plant of the Magna mill of the Utah Copper Co., with the hope of increasing the total recovery of gold. This was soon followed by placing various materials, such as coco matting, cotton twill, and common 10-oz. burlap on the bottom of the main tailing launder. The burlap was found to be the most economical material to use. The test was first conducted in an old wooden launder, 40 in. wide and 2000 ft. long, with 10-oz. burlap fastened

Jan 1, 1935

By David H. Browne

The use of coal-dust fired reverberatory furnaces, or indeed of rever-beratory furnaces of any description, was for the Canadian Copper Co. a matter of necessity, and not of choice. For 20 years smelting had been done in blast furnaces alone, and with the Herreshoff furnaces used prior to 1904 there was no trouble in treating fine ores. But little flue dust was produced, and this, following the time-honored custom, was wetted down and put back with the charge. Whether the flue dust really smelted, or whether it was worn out by being chased around in a circle, was a problem that troubled no one. With the installation of modern blast furnaces and high-pressure blowing engines, in 1904, flue dust commenced to assert itself. Evidently more dust was made than could be smelted, but so many vital. problems engaged our attention at that time that this minor question was pushed to one side. In 1906, the details of blast-furnace smelting and the conversion of matte had been worked out to a satisfactory conclusion, and the ever-increasing piles of flue dust and fine ore on the stock yard demanded serious consideration. Numerous experiments in sintering, briquetting, mixing with converter slag, forming blocks of flue dust with green-ore fines and cement, and so on, were undertaken. None of these showed much promise. Our problem was still further complicated by the question of treating converter slag. The ore was basic, the slag was not needed as a furnace flux, and it was felt that under these conditions the old method of pouring slag in molds and resmelting in the blast furnace was an unnecessary expense. If the converter slag could be settled in basic-lined reverberatory furnaces, in which at the same time flue dust and green-ore fines could be smelted, two problems might thus be solved. Reverberatory practice with our ores was, however, an unknown factor. As carried on in the West, on siliceous ores and concentrates, at least 25 per cent. of fuel was required, and even this ratio depended greatly

Jan 1, 1915

By AIME AIME

THE autumn is the time that nearly all the special groups within the broad field of the Institute's activitives chose for their own special meetings. The big annual meeting in New York in February has its own special advantages, but to realize them involves sacrificing others. A meeting of a smaller group with the subjects brought up for discussion much more closely limited to a single field of interest has some advantages that a big general meeting cannot possibly have. And so the custom has gradually developed of having these smaller meetings in the autumn, at con¬venient places, so the men will not have to travel too far from the job to be present. Sometimes the meetings have for their field of interest a single phase of mineral technology, and are called divisional, and at other times they cover a diversity of topics that are locally important in that geographical area, and are then called regional meetings. Of the five meetings to be held this fall, four are divisional and one regional. Two of the divisional meetings are to be held in the same place at the same time, but with programs so arranged that they do not conflict.

Jan 1, 1930

A discussion at a joint meeting of the New York Section of the American Electrochemical Society and the American Institute of Mining Engineers, Nov. 20, 1913. Chairman Lawrence Addicks:-Our program this evening represents an attempt to set before you the present situation and outlook in the metallurgy of zinc. It is a time-honored custom to throw bricks at the zinc man. The accusation is that he has borrowed a lime kiln and a gas retort and part of a sulphuric acid plant, hitched them together, and spent the last 50 years in regarding with holy veneration the reactions which take place in that retort. The copper man, who thinks of zinc as something with which copper is adulterated to make brass, and the iron man, who regards it as a sort of paint for corrugated sheets, and the lead man, whose opinion as to zinc is not fit for publication, have long felt that, when two or three of the minor details of their respective metallurgies were put in order, they would take a few clays and fix up zinc on a modern basis. But somehow there still seem to be some unsolved problems at home, and while we are waiting it seems only fair that the case for the defense should be adequately presented. There is probably no man in this country to-clay better able to do this than Mr. George C. Stone, of the New Jersey Zinc Co., on whom I have pleasure in calling to talk to us on "Progress in the Metallurgy of Zinc." George C. Stone:-It is frequently stated that there has been no change in the metallurgy of zinc since the first Belgian furnaces were built in the early part of the last century. It is true there have been no such spectacular and radical changes as were worked in the metallurgy of copper and iron by the introduction of converters; but, in the essentials, I believe the progress in zinc metallurgy has been as great as in that of the other common metals. The main reason that there have not been revolutionary changes is that the chemistry of zinc differs radically from that of the other metals and these differences control the type of apparatus that can be used. The differences are: 1. The temperature at which zinc is reduced by carbon is much above the volatilizing point of the metal and it is therefore always produced as a vapor.

Jan 1, 1914

By A. Weiss, W. A. Coster

The search for ore is characterized by a great variety of uncertainties, each of which can be resolved by obtaining information at a cost. Three exploration stages may be distinguished in which information can be obtained, based on inherently different cost structure: 1) the reconnaissance or scanning stage, 2) the examination or screening stage and 3) the project stage. This exploration sequence would roughly coincide with replies to questions as to: where, how, why and how much. As complete information in each stage is too costly to acquire, we must assess the probability that adequate information will be furnished by a limited amount of effort and attempt to maximize the expected value of ore to be found for a given exploration expenditure. Several problems are discussed relative to the mathematical formulation and possible computer procedures for determining the optimum allocation of a total exploration effort. Based on the available literature possible solutions to this problem are indicated. When scanning through published literature on mineral exploration, it seems at first that there is little room for substantial and systematic improvements in the efficiency with which the problem of discovery of new ore deposits is presently being handled by large organizations active in exploration. It appears equally difficult to offer something relevantly new which could generate a break-through in exploration thinking and cause a marked improvement in the ratio of successful undertakings to the total exploration projects started. On the other hand, a number of experts in recent years have urged that the problems in prospecting be analyzed in a more skillful and sophisticated manner than in the past. Their thesis is based mainly on the premise that the cost of finding mineral deposits will increase with increasing technical difficulties. In present large-scale exploration ventures, especially in those regions where outcrops and immediately visible geologic evidence are scarce, older methods of prospecting are increasingly being replaced by more indirect and systematic geophysical and geochemical methods with more emphasis on correct statistical design of exploration patterns. It is perhaps the oil industry which has made the greatest strides in developing statistically, well justified patterns in its search for oil; possibly because oil seepages, as indicators of the presence of oil, left off at an earlier point in time than did outcrops as indicators of base metals. Among the pioneers in the field of statistics and operations research, as applied to mineral exploration, the excellent works of Allais, Slichter, Koop-man, Mickey, de Guhnin, Krumbein, Griffith, Sichel, Krige, de Wijs, and Matheron may be mentioned. It should, however, be pointed out that three subjects of basic importance to the allocation of exploration efforts have so far received only scant attention in published literature, even by the aforementioned authors. In the first place, a more precise definition of the object of the search, i.e., a minimum-size orebody, seems to be outstanding. Secondly, a decision model is not a widely-discussed subject. Thirdly, no concentrated attempt so far seems to have been made to establish probabilities of the occurrence of economic deposits on a regional scale and to arrive at a slightly more accurate knowledge of the probability laws governing the deposition of ore. It is not the purpose of this paper to create new order in the complexity of uncertainties in which our decision processes in exploration necessarily have to be conducted. Rather, we intend to highlight some of the outstanding, hitherto unmapped territory, where diligent compilation and a utilization of present and historic data may statistically improve our chances of success. We hope that the contribution of this paper will lie in bringing allocation problems into better focus and in increasing the mineral industry's realization of the magnitude of the factors involved. THE MINIMUM-SIZE OREBODY The concept of target specifications for what constitute a minimum-size orebody in exploration is a rather variable one and depends to some extent on

Jan 1, 1963

In reply to inquiries and comments which have reached me since the publication of this paper, and in explanation of some seeming discrepancies between my statements in the text concerning the amount of displacement of the faults, on one hand, and certain figures in the plates on the other hand, I give here, with some additional remarks, my measurements of the displacements in the different sections, which it originally seemed unnecessary to print : By displacement, I mean neither the throw, i.e., the vertical distance apart of the two edges of a faulted bed (what Mr.

Jan 1, 1896

By M. A. Mahtab, J. D. Dixon

The results of a parametric study of the influence of natural features (stress field, rock strength, and strength and orientation of fractures) as well as the influence of induced features (undercut span, boundary slot, and other boundary-weakening measures) on the cavability of an undercut block of ore in mining by the block- caving method are presented. The two-dimensional finite-element analysis technique was used for this study. A coarse "mesh," along with linear homogeneous assumptions for rock properties, was used to model the problem of initiation of caving in a block of ore. Interpretation of the test results suggests that weakening the "abutments" of the block as well as certain orientations of natural fractures exercise significant influence on cavability. These findings hold promise for immediate application to known situations in block-caving mines.

Jan 1, 1977

President MRS. HARRISON SOUDER south Paramus Road Ridgewood, N. J. First Vice-president MRS. ROBERT HURSH New York N. Y. Second Vice-president MRS. RICHARD LLEWELLYN LLOYD Great Neck, L. I'. N. Y. Third Vice-president MRS. PERCY E. BARBOUR New York N. Y. Fourth Vice-president MRS. E. P. MATHEWSON Tucson Ariz.

Jan 1, 1937

By Frederic Benard

PRIOR to 1936, the Ontario Refining Co. received all incoming blister copper from The International Nickel Company's smelter in the usual form of 460-lb. cakes, or slabs. These were received in open cars in lots of 250 pieces. At the refinery the cakes were unloaded onto narrow-gauge cars, for convenient handling and pickup by charging cranes. In March 1936, an investigation was started on the feasibility of trans-ferring converter copper in the molten state from the smelter to the refinery anode furnaces, a distance of 114 miles. Although common in steel practice, the transportation of blister copper in this form had not previously been attempted and a preliminary study of the various factors involved was therefore necessary. For this purpose, a series of experiments was made in which molten copper, removed at different stages during the furnace cycle, was held in a small portable holding furnace. This vessel was essentially a refractory-lined steel cylinder provided with ports for filling and emptying, heated by an oil burner. Dimensions of the steel shell were 3 ft. 10 in. diameter by 7 ft. 3 in. long, and thickness of refractories depended oil the design and combination used for the particular experiment. The vessel was filled with approximately 2 ½ tons of copper at a predetermined temperature, the lining having been preheated to a definite point by means of an oil burner. All openings were well luted and temperature readings were made every 15 min. by means of an immersion-type thermocouple. In this manner the rate of heat loss resulting with different refractory design could be developed. The ratio of exterior surface to weight of metal was taken into consideration in comparing the experimental results with what might be expected for a full-sized unit, and observations were also made on type and degree of slag accretion. It was not possible to get as much information on this latter point as desirable, but all evidence showed that the problem would be control of slag build-up rather than attack oil refractories.

Jan 1, 1938