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By Richard Schellinger, Ronald H. Carlson, Robert D. Norris

INTRODUCTION A very important key to the success of an in-situ leach venture is proper choice of well field chemistry, in which type and concentration of oxidant plays a significant role. For proper design of well field and plant, an engineer must be able to estimate uranium production levels and their change with time. The rate controlling step in the uranium leach process is generally acknowledged to be the oxidation step (Goddard and Brosnahan, 1980; McKnight and Anthony, 1979; Mays, 1979). Uranium head grade is very dependent upon concentration of oxidant injected into the ore zone. If oxidant levels are too low, uranium production requirements will not be met; if levels ate too high, excess oxidant will be wasted in side reactions with gangue material and leach economics will suffer. To date, no reliable laboratory technique exists for generating data easily translatable to field conditions. Empirical correlations based upon lengthy field testing have been the major tools avail- able to the design engineer to date. During the past five years, FMC has developed lab- oratory techniques for studying uranium leach chemistry under conditions simulating as closely as possible the field situation. Both agitated batch and consolidated core leach procedures have been developed. Results of FMC agitated batch studies are described in detail in a companion paper (Carlson, et. al., 1980). This paper will focus on the technique developed for leaching consolidated undisturbed core under simulated down-hole conditions. Through use of a follow-up computer model (Winkley, 1980), generated data can be translated to expected field response, thus providing the design engineer with valuable information in a relatively short period of time. CHEMISTRY In addition to uranium (+4), other oxidant-consuming species present in uranium ore are iron sulfides and carbonaceous material. Iron sulfides are usually present in concentrations far exceeding those of the other two materials and, therefore, represent the major oxidant-consuming species present in uranium sandstone ore. Previous studies (Carlson, et. al., 1980) have shown that iron sulfides exist in both Texas and Wyoming ores as a mixture of pyrite and marcasite (FeSz); furthermore, uranium mineralization (existing as uraninite) was shown to exist as a fine granular material coating or imbedded in iron sulfide crystals and sand grains (i.e. quartz and feldspars). The leach chemistry of a uranium ore body can be described by the following equations using hydrogen peroxide (Hz021 as oxidant:

Jan 1, 1980

By C. E. MACQUICC

WITHIN a period considerably less than two decades, the engineering view of alloy steels has greatly changed-both as to their composition, and applications. Inasmuch as the elements used in manufacturing alloy steels are substantially the same as those which have been used for the past two or three generations, a statement like the foregoing may reasonably call for some explanation. The first commercial use of alloy steels in this country dates back to the sixties of the last century, when one of the earliest alloy steel patents, covering the use of chromium, was taken out by Bauer. About ten years later, German and French toolmakers began to introduce tungsten into tool steels. Developments along this line were more or less static for 25 years or more, the tool steel, compositions progressing along lines worked out by Mushet and one or two others in Europe. The next step in advance, made by Taylor and White inn the late nineties, consisted of heat-treating the alloy steels to enable much higher cutting speeds, thus introducing what soon became known as "rapid" or "high-speed" steels. All these developments being aimed toward the improvement of cutting tools, the compositions made were essentially of a hard, brittle nature. Following a different line of development started in the seventies, naval ordnance material began to embrace the nickel steels. These were rapidly popularized, became, and still are, with the addition of one or more elements, as chromium, molybdenum, vanadium, standard for heat-treated armor plate. During that period, however, no notable uses were made of alloy steels for engine parts or other high-stress parts where they are now considered indispensable; moreover, the present-day use of metals in the chemical industries was probably not even imagined. After the turn of the century, the necessity for making heavy-duty. machine parts, and especially the develop¬ment of the automobile, caused alloy steels to rapidly supplant plain carbon steels for engineering purposes.

Jan 1, 1930

DEPENDENCY on foreign sources for many mineral raw materials is a characteristic of our economy which is becoming painfully evident. Although investment in foreign mining projects has increased, it has not kept up with the growing demand for foreign minerals. The sphere of American investment capital in mining ventures abroad has been severely limited by the rise of nationalism in many underdeveloped countries. Consequently, we can look back over half a century in which mining investment, exclusive of petroleum, has increased by 50 pct whereas other American investments abroad have multiplied by better than 300 pct. Investment in foreign mining or petroleum encounters different problems than capital investment for other industries. It is rarely invested in industrialized nations. Most of it goes to countries with expanding frontiers, like Canada, or to underdeveloped nations like Liberia. It must be used for building communities, recruiting and training labor, and establishing lines of communication and transportation. These complications are an accepted part of the mining game. However, the most complex problem is in those countries which consider mineral exploitation a usurpation of the people's natural heritage. This is a characteristic of the young government existing by a tenuous balance of power in an underdeveloped nation. American mining capital understandably has shunned these nations as being poor investment risks. However, they possess minerals which are needed by industry. Our government has attempted to stimulate mineral supplies beyond those provided from abroad by private capital. ECA, now under DMPA, makes loans to foreign mining companies. Since the ECA program cannot be expected to continue indefinitely, Point IV seems to be the logical next step to encourage foreign countries to fill our shortages. However, only 1 pct of the $35 million budget provided in the first year for Point IV was alloted for mining programs. Considering the need for minerals and the difficulties of procuring them by private investment, a larger share is needed and justifiable. Those who have been engaged in foreign mining can vouch for the fact that it takes many decades to teach the complex technology and economics of mining to the natives of under-developed countries. For this reason Point IV must be considered a long range program. Mineral requirements for the present must be met by more direct measures. Encouragement of private investment in foreign mining by such incentives as tax relief on profits from foreign sources, international bank-borrowing facilities for private capital, and diplomatic assistance in encouraging foreign countries to cooperate are imperative for our future mineral security.

Jan 1, 1952

By A. U. Seybolt

RECENTLY, cases of coexisting ordered and disordered phase equilibria have been reported among face-centered cubic metals,1"3 but not on body-centered cubic systems.4 McQueen and Kuczynski5 showed a single line as the boundary between ordered solid solution of Fe3Al type and corresponding disordered solution in the Fe-A1 phase diagram based mainly on dilatometric and magnetic measurements. Such a single line would indicate a second or higher order transition. or an absence of coexisting order and disorder. The writer found previously a two-phase equilibrium region at 800°C consisting of ordered and disordered solid solutions of Fe3Si in a matrix of approximately 1-6 wt pct Si (Fe3Si is of 14.3 wt pct Si). A similar two-phase region of ordered and disordered Fe3Al solid solutions might be expected if the similarity between Fe3Si and Fe3Si structures hold true. In the present investigation, a wire of 22 at. pct Al, balance Fe and 0.0513 cm in diameter was subjected to electrical resistivity measurement in vacuum as a function of temperature between 300 and 800°C, see Fig. 1. There was excellent agreement between data taken on heating and on cooling: no hysteresis was observed. The Curie temperature was determined to be 640 °C which agrees with the finding by McQueen and Kuczynski.5 But in addition, there were two transitional points in the resistance-temperature plot at 510oC and 400 "C. The former is thought to be a connection with the transition from disordered state to a coexisting order and disordered equilibrium state; while the latter, from such coexisting state to ordered state. Fig. 2 shows a phase diagram where the suggested two-phase region lies between dotted lines. The solid lines are those of McQueen and Kuczynski.5 Since these authors found only a single-phase boundary between ordered and disordered Fe3 Al, it would seem likely that the dilatometric method used by these authors was not sufficiently sensitive to resolve the ordering reaction into the two-phase boundaries. In addition, their phase diagram conflicts with the statement they make on P. 1 of their paper: "The sharpness of the peaks indicates that ordering to Fe3A1 is a first order reaction." The suggestion of coexisting order plus disorder in Fe3A1 must be considered tentative until confirmed by high-temperature X-ray examination. If

Jan 1, 1961

By Ralph J. Schilthis

Several investigators1-8 have reported evidence of the existence of native or connate water in oil-and-gas-bearing strata. Both water and salt have been detected in cores of oil sands that yielded oil and gas exclusively when produced. Electrical logs often reveal unexpectedly low resistivity through oil and gas sands, indicating the presence of some material that is a considerably better conductor of current than oil and gas. Furthermore, calculationsg of the oil and gas content of reservoirs based upon production and reservoir-pressure decline data indicate appreciably lower values than are arrived at under the assumption that the pore space is occupied completely by oil and gas. Origin and Occurrence of Connate Water in Oil-and-gas-bearing Formations The view has been expressed, 10-15 and is generally agreed upon, that the expulsion of oil and gas material from source beds and the subsequent migration and accumulation occurred in the presence of salt water. As the strata that usually form reservoirs for oil and gas were laid down by, or in the presence of, ancient seas, the pore space within the strata must have been saturated with salt water before the entrance of the oil and/or gas. Thus, the accumulation of oil and/or gas in the upper regions of structures suitable for reservoirs must have required displacement of the connate water therefrom. In the absence of any forces other than gravitational, it would be expected that the displacement of the connate water out of the zones finally occupied by gas and oil would be complete, and that the vertical distribution of gas, oil, and water in a reservoir would be strictly in the order of their densities. Apparently, however, surface and interfacial forces that will not permit complete segregation of the fluids are active within the capillary spaces comprising a reservoir. The effects of these forces on both accumulation and production of oil and gas have been the subject of study by a number of investigators.16-37 In general, the view is held that the character of most materials that make up the reservoir rock leads to preferential wetting of the rock by

Jan 1, 1938

By S. K. Nowak

The lithium solubility limit in solid aluminum was determined by the use of micro-graphic techniques. The solubility limit thus established was shown to be a true equilibrium by checking the reversibility of AlLi phase precipitation and dissolution around the equilibrium temperature. The experimental results fit a straight line by plotting log N(LI) against 1/T. The metallurgical reasons explaining the lack of agreement among previous investigations are discussed. THE solubility limit of lithium in solid aluminum was determined by Shamray and Saldau1 by micrography and by Grube et al.' and also Voss-Kiihler- by measurement of electrical resistivity. Since the addition of lithium induces extremely small changes in the aluminum lattice, X-ray techniques could not be employed for this purpose; in fact, the addition of lithium does not cause an expansion of the lattice as might be expected from a consideration of atomic radii, but causes a small contraction from 4.040 to 4.037A3, 4 when the solvent aluminum is saturated with this element. An analysis of the results from previous investiga-tions'" shows that with improvement of investigation techniques the solubility limit tends toward a lower lithium content. Again, some of the author's own experimental results on the action of atomic hydrogen on A1-Li alloys seemed to indicate that the solubility of lithium should be much lower, i.e., about 0.3 pet at 300°C: instead of 1.15 pet, the lowest published value.4 For the foregoing reasons it was decided to investigate this problem. The aluminum and the lithium used for this purpose were of the highest purity. The lithium solubility limit was determined by metallographic techniques, in particular by the use of a reagent especially developed for the purpose of revealing the AlLi phase. The solubility limit thus determined was shown to be a true equilibrium by checking the reversibility of AlLi phase dissolution and precipitation around the equilibrium temperature. All of the experimental work was carried out in 1951 at the Centre d'Etudes de Chimie Metallur-gique at Vitry, France, under the direction of Georges Chaudron.

Jan 1, 1957

By C. W. Mason

TIN has long been cited as offering a classic example of polymorphism, second in repute only to the allotropy of sulphur. The notorious "tin disease," which Cohen1 has studied so exhaustively in terms of the enantiotropic transformation of tetragonal white 0 tin to cubic gray a tin, has apparently encouraged the expectation that one or more addi-tional polymorphic modifications might exist. The search for confirma-tion of this idea has, as might be anticipated, led to the accumulation of a body of miscellaneous evidence, much of which would probably never have been sought, or taken seriously even by its discoverers, but for previous assumptions. The ball apparently was started rolling in 1880 by Trechmann,' who reported a new modification of tin (y tin), which was brittle and found in "hard head," a highly arsenical, slaggy material produced in a certain stage of tin smelting. A mixture of two kinds of crystals was obtained from a Cornish tin furnace, and those thought to be y tin were studied crystallographically. The results indicated that these crystals were rhombic and of different density from the tetragonal tin prepared electrolytically by Miller.3 Their analysis was given as 98.7 per cent Sn, 1.3 per cent Fe, and traces of As, Sb, Bi and S. In 1881 von Foullon4 obtained similar crystals from a Bohemian tin furnace. Headden5 examined crystals similar to those of Trechmann and von Foullon and reported them to be monoclinic, but of analysis corresponding to stannous sulphide. Later, Stevanovic,6 by goniometric measurements, proved that these crystals of SnS were really rhombic. Groth7 pictures and describes both "rhombic tin" (Fig. 9, vol. 1) and stannous sulphide (Fig. 84, vol. 1); their faces and angles correspond within the accuracy of measurement. Spencer3 in 1921 examined the above evidence critically; he found similar crystals from Cornish tin furnaces, proved them to be SnS, and even was able to analyze some of Trechmann's original specimens, finding high sulphur content. (Apparently Trechmann's analysis had been based on a second lot of crystals, not described crystallographically.)

Jan 1, 1939

By Arnlf Muan, Bert Phillips

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

Jan 1, 1961

By W. H. Craigue

The scope of this article covers only the mathematical principles involved in discounting to present worth future expected profits and it is believed answers definitely two questions, which were raised at a recent meeting of the Committee on Methods of Valuing Coal Properties, as follows: 1. The accumulative effect of carrying charges on the value of coal mines showing definitely the number of years beyond which the coal may not be mined at a profit and subsequent to which the possession of any unmined coal will be a liability rather than an asset. 2. The effect on the valuation of coal mines, in the presence of the carrying charges described in question 1, of an increase in plant capacity and production. In general, in considering these questions, it may be stated that the consideration of an increase in plant capacity and production follows as a matter of course after a determination has been made of the year beyond which no profits are to be realized (giving the carrying charges accumulative effect, or in other words capitalizing the carrying charges, as shown hereinafter). For example, if it is determined that any coal that is unmined after 45 years will have no value or less than no value, the question immediately arises as to whether or not a plant should be constructed that would result in a yearly production great enough to extract the entire tonnage in a time less than 45 years, and if so the number of years less than 45 years that would, from a financial standpoint, be the most desirable, all under the assumption that the market for the product or the transportation facilities are such that the yearly production can be increased to the desired amount. Specifically, the carrying charge is considered herein as yearly expense, such as state or local taxes, which are assessed each year against the total tonnage remaining in the ground (or the total coal acreage remaining) at the beginning of the year, at a fixed rate per ton (or a fixed rate per acre) OF a fixed percentage of the assessed value, in the latter case it being necessary to convert such percentage into a rate per

Jan 1, 1934

By G. S. Rice

With so tremendous a subject, an attempted review of the coal situation of the world in a short talk must necessarily be of a sketchy character. It is hardly necessary to tell a body of engineers that had it not been for nature's gift of coal the material side of modern civilization would never have reached its present status. On the other side, it is regrettable that it was a byproduct of coal, T. N. T., which made possible Germany's initial success in this war, because that country had an enormous development of manufacturing plants that could be immediately utilized to make this destructive agent: One sometimes hears the casual remark that when the coal of the world is exhausted we shall use electricity; but, of course, electricity is ordinarily only a means of transforming and transmitting energy derived from fuel or water power, and chiefly from coal. It is true, we have much undeveloped water power, but it is more or less remote from 'the, centers of industry; and when all shall have been developed it will not begin to supply the power requirements of the world. It is, however, reasonable to expect that before the world's supply of coal shall be exhausted, methods will have been discovered of harnessing other forces of nature, such as the tides, or the energy emanating from the sun. Petroleum and natural gas naturally come to mind, but the days of both, as fuel, appear to be numbered, although the products of petroleum, if economically used, doubtless will be available for internal-combustion engines, automobiles, trucks, and boats for a long time, provided the reckless use of crude petroleum as an ordinary fuel is stopped. The products of petroleum are too valuable to mankind for such waste to be permitted. The civilization of the world, therefore, appears to rest, and, so far as can be seen, will indefinitely continue to rest, upon coal. COal Resources of the World According to the compilation made by the geologists of the principal countries for the 12th International Geologic Congress, held in Canada

Jan 1, 1918

By B. G. Zambre, G. A. Parks, J. N. Roco

Automatic controls have long been a fact of technological life. Some understanding of control systems is rapidly becoming essential to the competence of mineral engineers. Students in undergraduate mineral engineering curricula, however, should not be expected to develop proficiency in the design and interpretation of control systems. They should be provided the opportunity to absorb some of the fundamental concepts and cant of such highly specialized peripheral fields as automatic controls. The present paper describes the components of a simple, flexible and relatively inexpensive control system designed primarily for the use of students in independent study projects. The control system is based on a continuous on-stream optical analyzer analogous to commercially available systems using X-Ray fluorescence analysis. The components can be easily adapted to control other separators and separations. As described here, they have been arranged to control the magnetic separation of a magnetite bearing specular hematite from quartz to produce a quartz product of fixed hematite content using a minimum of power. The control system consists of the magnetic separator* with a vibrating feeder, † a sampler, an optical scanner, a differential amplifier, a millivolt recorder ‡ and a motor driven, metered variable DC power supply for the separator electromagnet. An optional magnet current recorder is useful. The system as arranged for closed loop control is illustrated in Fig. 1. The elements of the loop are identified in automatic control jargon in Table I. The same components can be easily adapted for use in other control modes.§.1 * A Carpco Induced Roll High Intensity Magnetic Separator (Carpco Manufacturing, Inc., Jacksonville, Fla.); modified for external magnet power supply. A Jeffrey-Traylor Vibrating Feeder Type 1B (Jeffrey Manufacturing Co., Columbus, 0.). A Beckman Laboratory Potentiometric Recorder (Beckman Instruments, Inc., 619-A) fitted with adjustable limit switches for external circuit control (Beckman Instruments, Inc.. 71980). Terminology is taken from ref. 1. CLOSED LOOP OPERATION The separation is monitored through the optical reflectivity of the tailings stream which is proportional to the hematite content, THA. The difference, A, between the measured analysis (actually a proportional voltage) and a reference analysis (also a proportional voltage) is continuously recorded. The separation is controlled through changes in the electromagnet current, I, supplied from a motor driven variable source. The two primary variables, ? and I, are linked through adjustable limit switches on the

Jan 1, 1965

By E. P. Hindes

The total amount of oil produced in the state of Oklahoma during the year 1928 was 242,286,400 bbl., as compared to 273,372,650 bbl. in 1927; 177,650,000 bbl. in 1926; and 167,900,000 bbl. in 1925. The year 1928 ranks second to 1927 in which more oil was produced in the state than in any previous year. The large in in 1927 and 1928 was due principally to the development of the Greater Seminole district. The decrease of approximately 31,000,000 bbl. in the 1928 production as compared with the production in 1927, was caused by a drop of nearly 8,500,000 bbl. in the Seminole district production and a more or less normal decline in the production of practically all the other older and more settled fields. During 1928 approximately 1800 producing wells were drilled in Oklahoma, which yielded during the year approximately 90,000,000 bbl. of oil. The average initial production of these wells was 850 bbl. per day, and the average daily production per well for the year was 137 bbl. The average daily production per well of the total number of wells producing in 1928 was 10.9 bbl., which is a 13.5 per cent. decrease from the 1927 average of 12.6 barrels. At the close of 1928 a total of 95,400 producing wells had been drilled in the state, and approximately 61,000 were still producing. The grand total amount of oil produced in the state from the time the first well was drilled up to and including 1928 was 2,553,000,000 bbl. The production in 1928 was 9.5 per cent. of the total oil produced in the state. Texas led all other states in 1928, with a production of 251,835,200 bbl. Oklahoma was second with 242,286,400 bbl., and California was third with 231,982,600 barrels. Fields outside Greater. Seminole District Practically all the old settled fields in Oklahoma experienced a normal and expected decline during the year 1928. The fields showing the most, pronounced decline as compared to 1927 were: Burbank, which dropped from 15,230,400 to 11,939, 150 bbl.; Tonkawa, from 7,692,000 to 4,952,900 bbl.; Garber, from 5,056,300 to 3,139,400 bbl., and Wewoka, from 6,188,-800 to 2,450,400 bbl. There were no new extensions, discoveries of

Jan 1, 1929

By Julian M. Avery

IN its dual role of pig-lion smelter and gas producer, the blast furnace is a remarkably satisfactory and efficient apparatus Many metallurgists and engineers have pointed out, however, that since the primary function of the blast furnace is to produce pig iron at the lowest possible cost, its function as a gas producer should be subordinated to this primary purpose During the past 10 years or more, improvements in blast-furnace technique and economy have, n fact, been directed primarily to increasing efficiency n the use of the reducing power of the gases produced by combustion of coke at the tuyeres, to reduce iron ore within the furnace The net over-all result is a decrease n the fuel value of the top gas per unit of volume, and per ton of pig iron, which is evidently amore than offset n value by the corollary saving in coke and the possibility of increased furnace capacity, for otherwise there would be no point in making such improvements The purpose of the present paper is to suggest that, while progress has been made n this direction, there is another approach to the problem of increasing the chemical and thermal efficiency of the blast furnace in its primary role as a pig-iron smelter, which appears to offer possibilities of improvement in over-all economy of a different order of magnitude than results thus far obtained by the use of other expedients The present argument is based in large part upon the hypothesis that the efficiency and economics of pig-iron smelting are seriously and adversely affected by the phenomenon known as "solution loss," and that the problem of solution loss can be successfully attacked by increasing the over-all pressure, i e , the "top pressure" under which the furnace is operated It is indicated that pressure operation may also be expected to result n concomitant benefits, which may be summed up as generally improved operating conditions, together with a substantial saving in fuel and/or a substantial increase in furnace capacity In a broad sense, the suggestion of pressure operation of the pig-iron blast furnace is not new, for operation under moderately increased over-all pressure was suggested as early as 1871, by no less an authority than

Jan 1, 1938

By Eugene F. Poncelet

This paper attempts to analyze the phenomena involved in the fracture of brittle solids by simple compression. Glass squares standing on edge, and compressed between two parallel steel jaws, developed jagged fractures, roughly parallel to the compression. Polarized light disclosed the presence of high local stress concentrations indicating poor contact all along the contact surfaces with the steel jaws. Teszar has shown that partial contact between the jaws and such a compressed solid causes tensile stresses in the free surfaces of the solid normal to the compression. Furthermore, Scoble has shown that in brittle solids fractures are caused by, and develop normally to, a sufficient tensile stress. It follows that such "partial-contact" cracks must be expected. With optically flat jaws and specimens, no "partial-contact" cracks developed. Instead, very smooth cracks vertical to the compression appeared 'upon release of the pressure. Investigation showed that the friction with the rigid steel opposed the return of the glass to its original width, after creeping on the steel as compression built up, thus setting up tensile stresses in the glass surfaces. It was not found possible to eliminate these "release" cracks. Compressed to destruction, such specimens flew to dust. A Microflash photograph taken during the explosive disintegration revealed: (I) oblique parallel fragmentation cracks, 30" off the direction of the compression; (2) transverse forking fragmentation cracks, normal to the former; (3) release cracks parallel to the compression; (4) a disintegration cloud. Given a distribution of submicroscopic cracks of random orientation throughout the glass, Griffith has shown the highest tensile stresses to be located at the tip of the cracks 30" off the direction of the compression. Although the preexistence of such cracks or flaws in unstressed glass is doubtful, they can be generated by the distorting forces set up by the compression itself. Atoms, in a structure held together by Morse-type forces or bonds, have under tension both a stable and an unstable state-of equilibrium. The difference in energy level between these two states is a function of the tension, and this difference must be borrowed from the thermal energy level of the bonds to reach the unstable state and result in a broken bond. As the fraction of the bonds having at any instant a sufficient thermal energy level is a known function of that level, it is possible to determine, in function of the prevailing tension, the fraction of the bonds that are broken. Upon breaking of the bond uniting two atoms at the tip of an advancing crack, the two atoms accelerate away from each other, causing in the solid propagation of a

Jan 1, 1944

By Eugene F. Poncelet

This paper attempts to analyze the phenomena involved in the fracture of brittle solids by simple compression. Glass squares standing on edge, and compressed between two parallel steel jaws, developed jagged fractures, roughly parallel to the compression. Polarized light disclosed the presence of high local stress concentrations indicating poor contact all along the contact surfaces with the steel jaws. Teszar has shown that partial contact between the jaws and such a compressed solid causes tensile stresses in the free surfaces of the solid normal to the compression. Furthermore, Scoble has shown that in brittle solids fractures are caused by, and develop normally to, a sufficient tensile stress. It follows that such "partial-contact" cracks must be expected. With optically flat jaws and specimens, no "partial-contact" cracks developed. Instead, very smooth cracks vertical to the compression appeared 'upon release of the pressure. Investigation showed that the friction with the rigid steel opposed the return of the glass to its original width, after creeping on the steel as compression built up, thus setting up tensile stresses in the glass surfaces. It was not found possible to eliminate these "release" cracks. Compressed to destruction, such specimens flew to dust. A Microflash photograph taken during the explosive disintegration revealed: (I) oblique parallel fragmentation cracks, 30" off the direction of the compression; (2) transverse forking fragmentation cracks, normal to the former; (3) release cracks parallel to the compression; (4) a disintegration cloud. Given a distribution of submicroscopic cracks of random orientation throughout the glass, Griffith has shown the highest tensile stresses to be located at the tip of the cracks 30" off the direction of the compression. Although the preexistence of such cracks or flaws in unstressed glass is doubtful, they can be generated by the distorting forces set up by the compression itself. Atoms, in a structure held together by Morse-type forces or bonds, have under tension both a stable and an unstable state-of equilibrium. The difference in energy level between these two states is a function of the tension, and this difference must be borrowed from the thermal energy level of the bonds to reach the unstable state and result in a broken bond. As the fraction of the bonds having at any instant a sufficient thermal energy level is a known function of that level, it is possible to determine, in function of the prevailing tension, the fraction of the bonds that are broken. Upon breaking of the bond uniting two atoms at the tip of an advancing crack, the two atoms accelerate away from each other, causing in the solid propagation of a

Jan 1, 1944

By W. T. Thom

ALL engineering education is faced by certain basic problems, three of which seem to have particular present importance in geological engineering training in general, and in respect to training for oil field geoexploratory work in particular. PROBLEM I The first of these problems has to do with present and future educational objectives and with the numbers and qualities of the men who should be coming out of our geoexploratory training programs. Before the war we needed ever-increasing numbers of graduates at the Bachelor's level and a very much smaller number of men who had reached the Doctorate degree. Now, with more difficult, more extensive, and more costly exploratory work; with a rapid expansion of company "staff" activities, and with the initiation of many new research organizations and laboratories; it is clear that men of exceptional ability will be more and more in demand, and that the schools will need to carry a greater proportion of their students through to the Ph.D. degree. PROBLEM 2 Assuming that the mineral industries will need an increasing supply of well-qualified Ph.D.s for future geoexploratory work (staff, line and research), can the schools expect to provide this supply of able Ph.D.s merely by expanding the proportion of B.S. and B.A. majors who go on through to the doctorate stage of training? And the answer is definitely "No "-as the situation stands at present. Most A.B. graduates are years short of the preparations in basic science and elementary engineering prerequisite to effective graduate study in the geoexploratory fields (paleontology excepted), and similarly many of the annual crop of B.S. graduates lack adequate training in English; in ancient and modern history; and in the modern principles of labor and public relations. Indeed, several basic problems of undergraduate curricular organization and integration remain to be solved before most recipients of a Bachelor's degree will have that sound and broad educational foundation prerequisite to graduate training on a really effective basis. It is for these reasons that we have continued to experiment with our geological engineering program at Princeton, in an endeavor to provide a pilot-plant demonstration of a suitably broad and flexible undergraduate curriculum. PROBLEM 3 But assuming that the schools can and do get undergraduate curricula set up in proper phase and scale to meet needed enrollment quotas for graduate training, what about the most urgent part of our whole mineral-industry educational problem? What about finding and bringing into mineral-industry training those youngsters of superior ability who are, by potential or known inclination, especially well-qualified for geoexploratory work?

Jan 1, 1947

By Klaus Schwerdtfeger, Leo Zwell

The equilibrium between Ir-Fe or Rh-Fe alloys, iron oxide (wüstite or magnetite), and CO2-CO atmospheres has been determined at 1200°C. The data are used to derive the activities in these binary solid solutions. Both systems show negative deviations from Raoult's law. The lattice parameters are given for the investigated Ir-Fe and Rh-Fe alloys. IRIDIUM and iron form a continuous series of fcc solid solutions at elevated temperatures.' Rhodium-rich Rh- Fe alloys have fcc structure.' In the medium concentration range an ordered bcc phase is stable at temperatures up to about 1300°C. Phase relations in iron-rich alloys are not well-known. No thermody-namic data are available for these alloys. EXPERIMENTAL METHOD The experimental method used was to measure the equilibria between a gas phase of known CO2/C0 ratio, the alloy, and iron oxide (wüstite or magnetite). In one series of experiments the alloys of known composition were heated in CO 2-CO gas mixtures. After treatment (usually 1 day) the sample was quenched to room temperature and its surface examined visually to determine whether an oxide tarnish had formed. The procedure was repeated at slightly higher CO 2/CO ratios until the CO 2/CO ratio of incipient oxidation was found. Subsequently, the CO 2/C0 ratio was lowered again in small increments until the tarnish was reduced. In other experiments mixtures of alloy and iron oxide powders were pressed into pellets and equilibrated with the CO2-CO gas phase. In order to ensure that equilibrium was attained, two specimens with different starting iron content were heated side by side; in most cases, equilibrium was approached in one pellet by reduction of iron oxide and in the other pellet by oxidation of metallic iron. The sample was quenched to room temperature, and the composition of the equilibrated alloy was determined by X-ray measurements of lattice parameters and comparison of these values with calibration curves obtained from alloys of known composition. The oxides present in the specimens were identified by comparison of their diffraction patterns with those in the ASTM Card File. It may be expected from the noble character of iridium and rhodium that no appreciable amount of iridium or rhodium is dissolved in wiistite and magnetite under the present experimental conditions. The activity of iron in the alloy is then equal to that established in the iron oxide by the COrCO atmosphere. The activities of iron in wüstite and magnetite, as a function of oxygen pressure, were taken from the work of Darken and Gurry,

Jan 1, 1969

By L. D. HUNTOON

MY first article on Canadian Gold, published in the Canadian Mining Magazine in 1911 expressed the view that the Hollinger mine would repay all the money invested and that other mines would be developed in this area. Many published forecasts have since been made. Quoting from the Northern Miner of Oct. 29, 1931: "It will be noted in studying the chart prepared by this engineer that his forecast for 1931 at $50,000,000 was too modest, as the output for this country this year will be closer to $54,000,000."

Jan 1, 1932

By William F. Boericke

RESEARCH in the modern refractories laboratory has two practical ends in view-to develop refractory materials for the metallurgist that will meet particular operating difficulties more effectively and to ?manufacture these refractories at a cost sufficiently low to make their use economical to the metallurgist. At the research laboratories of E. J: Lavino and Co., at Plymouth Meeting, Pa., the technical staff, under Dr. Gilbert E. Seil, is giving principal attention. to an. exhaustive investigation of the following factors in refractories:

Jan 1, 1931

By AIME AIME

THE papers presented at the geophysics session" on Feb. 17 were concerned largely with three aspects of the science. The first ones dealt with the transmission of elastic waves through the earth, then electrical methods came in for their share of attention and finally, the question of the teaching of geo- physics came up for the first time at these meetings. Also, for the first time, there was a symposium of mining men on the practical value of the new science. The paper (T. P. 267) entitled "Seismic Propagation Paths" was presented by Donald C. Barton in the absence of the authors. It dealt with an investigation of the speed of propagation of seismic waves. The latter travel in a straight line when proceeding at a constant velocity, but if the velocity increases at increasing depths, the line of travel becomes a curve. Under the assumption of the authors this curve is found to be the arc of a circle, and their paper gives calculations for reflected and refracted wave paths under these circumstances.

Jan 1, 1930