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By W. H. McFarland

The mechanical properties have been determined for a large number of alloy-free martensitic steels with carbon contents ranging from 0.08 to 0.20 pct and with manganese contents of about 0.4 to 0.5 pet. These steels were tested 1) as water-quenched, 2) after quenching, temper rolling, and tinning, and 3) after tempering treatments which involved temperatures from 400o to 1300oF and times from 1 min to 8 hr. The majority of these tests represent steel from commercial-size coils, i.e., strip 32 in. wide, coil weights up to 20,000 16, and steel thicknesses from 0.0055 to 0.024 in. As a result of these treatments, it has been shown that as-quenched low-carbon alloy-free steels can be produced with tensile strengths ranging from 140,000 to 220,000 psi and tensile elongations from 3.0 to 4.0 pet in 2 in. The tensile strength of the as-quenched martensites can be represented by the equation, tensile strength (ksi) = 119 + 560 (wt pet C). The response to tempering of these steels is related to previous work by Muir, Averbach, and Cohen and by Grange and Baughman. Strain aging of low-carbon martensite has also been investigated. If low-carbon steels are defined as those steels with a maximum carbon content of 0.2 pet, it is found that the literature on low-carbon, alloy-free martensites contains little data on the mechanical properties of these steels. However, the following facts concerning low-carbon alloy-free martensites seem firmly established:'-' 1) The major factors in controlling the strength of the martensite appear to be a) fine structure, b) the internal strain resulting from the transformation, and, particularly, c) the amount of carbon in solid solution. 2) In low-carbon steels, the martensite is auto-tempered and is in the form of needles with only minor amounts of internal twinning, whereas the martensite in high-carbon steels forms as plates which are internally twinned on a fine scale. 3) Care must be taken in comparing the results of work that has been done on low-carbon steels with varying amounts of alloying elements to data on plain carbon steels. As has been noted by Irvine, Pickering, and Garstone,6 alloying elements generally lower the martensite start temperature and, thereby, decrease the amount of auto tempering obtained during the quench. This makes it difficult to

Jan 1, 1965

By E. B. Phillips, A. E. Miller

The title assigned to this paper permits a discussion of one of the most interesting chapters in the history of the American petroleum industry. Nature was kind to man when she prepared crude oil for him in commercial quantities in the hills of Northwestern Pennsylvania. Most of the refining operations we are now accustomed to apply were either not needed or had been carried out by earth processes ages ago. Such technology as was applied dealt with the physical separation of the valuable components in the crude oil and intermediate products and did not need more than mild refining treatments to bring them to marketable quality. • The pioneer refiners were concerned principally with distilling, dewax-ing and decolorizing operations. The products produced were limited in number and the uses to which they could be put were few. Natural products from the very high grade crudes, then plentiful, supplied the domestic demand and no other markets were open. As time passed, other producing fields were discovered and crude oils of lower natural quality were made available. To refine these grades to a quality expected by buyers, refinery practice had to be changed and new methods found. At the same time the accidental discovery that crude residues could be cracked by dry distillation at atmospheric pressure to produce a much larger amount of lamp oil than had been customary, opened a new vista for the industry. Export kerosene soon became the leading revenue product for all refiners and considerable new technic was added to refinery practice. High sulfur crude oils from Ohio next made their appearance, causing the development of the first commercial desulfurizing process, the sodium plumbite treating method for "sour" lamp oil stocks and the application of fine earth for the removal of "flock." Some improvements in methods of handling lubricating oils and cylinder stock fractions of crude were worked out, but in general, it can be said that the closing decade of the last century found the industry in a stabilized condition. Typical refinery operations of 1900 were simple and were conducted with the single purpose of producing as much export kerosene as possible Light naphthas and fuel oils were a drug on the market and every means

Jan 1, 1928

By Donald C. Branford

The place of geophysics in the curriculum of a college or an engineering school has been much discussed. There is uncertainty as to whether the graduate may be called a "geological geophysicist" or a "geophysical geologist." Some have used the term "geophysical engineer." The question of the specialized undergraduate curriculum versus a general undergraduate training in the parent sciences with the addition of cultural electives has been and is still being argued. The literature during the past Io years shows that there are two rather definite schools of thought on this subject. The prospective employer, engaged in active geophysical exploration, visualizes the graduate in terms of the routine work he will do in the field. The school administrator, grounded in many years of tradition in the cultural type of education, visualizes the graduate in terms of his position in a political and cultural society as well as in his work as a professional geophysicist. Both are right and both wrong. A third school of thought, that of the student himself, has been almost totally ignored. It would seem best, for the purpose of this paper, to treat these various points and allied material separately, and then to integrate the conclusions as a set of conditions that should be fulfilled as far as possible in the ideal curriculum. At the end the relationship of our findings to the curriculum that has been tentatively adopted at the University of Pittsburgh will be considered. Divisions in Definition or Field of Geophysics Geophysics is that field of science in which geological and earth problems are solved with the use of physical and chemical techniques. Altogether too much attention has been paid to the artificial separation in this science of the commercial applications from the so-called "pure" or academic geophysics. The only real difference in the two types of work is one of scale of operations. In the commercial field the scale is large in terms of fmancial backing, immediate economic importance, and speed of operations. In the academic field the scale is large in terms of breadth of interests, in eventual economic importance, and length of time allowable for theoretical investigations. In exploration work the scale is small in terms of dimensions, since the methods are applicable only to the outer 20,000 ft. or SO of the earth's crust. In academic work, the student is not pressed for results of immediate economic importance, and therefore can afford to spend more time on problems that seem unimportant at the time. In the sense of background knowledge of the parent sciences necessary to the geophysicist, no essential difference can be found. Physics, chemistry, geology, and mathematics together, and in their proper proportionate amounts, form the matrix from which geophysical ideas and methods may spring.

Jan 1, 1946

By Donald C. Bradford

THE place of geophysics in the curriculum of a college or an engineering school has been much discussed. There is uncertainty as to whether the graduate may be called a "geological geophysicist" or a "geophysical geologist." Some have used the term "geophysical engineer." The question of the specialized undergraduate curriculum versus a general undergraduate training in the parent sciences with the addition of cultural electives has been and is still being argued. The literature during the past 10 years shows that there are two rather definite schools of thought on this subject. The prospective employer, engaged in active geophysical exploration, visualizes the graduate in terms of the routine work he will do in the field. The school administrator, grounded in many years of tradition in the cultural type of education, visualizes the graduate in terms of his position in a political and cultural society as well as in his work as a professional geophysicist. Both are right and both wrong. A third school of thought, that of the student himself, has been almost totally ignored. It would seem best, for the purpose of this paper, to treat these various points and allied material separately, and then to integrate the conclusions as a set of conditions that should be fulfilled as far as possible in the ideal curriculum. At the end the relationship of our findings to the curriculum that has been tentatively adopted at the University of Pittsburgh will be considered. DIVISIONS IN DEFINITION OF FIELD OF GEOPHYSICS Geophysics is that field of science in which geological and earth problems are solved with the use of physical and chemical techniques. Altogether too much attention has been paid to the artificial separation in this science of the commercial applications from the so-called "pure" or academic geophysics. The only real difference in the two types of work is one of scale of operations. In the commercial field the scale is large in terms of financial backing, immediate economic importance, and speed of operations. In the academic field the scale is large in terms of breadth of interests, in eventual economic importance, and length of time allowable for theoretical investigations. In exploration work the scale is small in terms of dimensions, since the methods are applicable only to the outer 20,000 ft. or so of the earth's. crust. In academic work, the student is not pressed for results of immediate economic importance, and therefore can afford to spend more time on problems that seem unimportant at the time. In the sense of background knowledge of the parent sciences necessary to the geophysicist, no essential difference can be found. Physics, chemistry, geology, and mathematics together, and in their proper proportionate amounts, form the matrix from which geophysical ideas and methods may spring.

Jan 1, 1942

By Donald C. Branford

The place of geophysics in the curriculum of a college or an engineering school has been much discussed. There is uncertainty as to whether the graduate may be called a "geological geophysicist" or a "geophysical geologist." Some have used the term "geophysical engineer." The question of the specialized undergraduate curriculum versus a general undergraduate training in the parent sciences with the addition of cultural electives has been and is still being argued. The literature during the past Io years shows that there are two rather definite schools of thought on this subject. The prospective employer, engaged in active geophysical exploration, visualizes the graduate in terms of the routine work he will do in the field. The school administrator, grounded in many years of tradition in the cultural type of education, visualizes the graduate in terms of his position in a political and cultural society as well as in his work as a professional geophysicist. Both are right and both wrong. A third school of thought, that of the student himself, has been almost totally ignored. It would seem best, for the purpose of this paper, to treat these various points and allied material separately, and then to integrate the conclusions as a set of conditions that should be fulfilled as far as possible in the ideal curriculum. At the end the relationship of our findings to the curriculum that has been tentatively adopted at the University of Pittsburgh will be considered. Divisions in Definition or Field of Geophysics Geophysics is that field of science in which geological and earth problems are solved with the use of physical and chemical techniques. Altogether too much attention has been paid to the artificial separation in this science of the commercial applications from the so-called "pure" or academic geophysics. The only real difference in the two types of work is one of scale of operations. In the commercial field the scale is large in terms of fmancial backing, immediate economic importance, and speed of operations. In the academic field the scale is large in terms of breadth of interests, in eventual economic importance, and length of time allowable for theoretical investigations. In exploration work the scale is small in terms of dimensions, since the methods are applicable only to the outer 20,000 ft. or SO of the earth's crust. In academic work, the student is not pressed for results of immediate economic importance, and therefore can afford to spend more time on problems that seem unimportant at the time. In the sense of background knowledge of the parent sciences necessary to the geophysicist, no essential difference can be found. Physics, chemistry, geology, and mathematics together, and in their proper proportionate amounts, form the matrix from which geophysical ideas and methods may spring.

Jan 1, 1946

Payloader The Frank G. Hough Co. has made available another four-wheel drive tractor-shovel. It has a 1 cu-yd bucket with 60 hp Diesel or 54 hp gasoline power optional. The use of large pneumatic tires, same size all around, and drive on all four wheels gives this new Payloader traction to work effectively in sand, mud and snow, and travel on pavements with- [ ] out injuring the surface. Rear wheel steer with power booster plus short wheel base makes it easy to operate and highly maneuverable. Four speeds in both directions insure fast travel speeds for transport and fast operating speeds on shuttle loading or similar operations. Bulldozer blade, crane hook, fork lift and snow plow attachments are available, quickly interchangeable with the bucket to further increase its multi-purpose usefulness. Circle No. 1

Jan 1, 1952

By Wallace E. Pratt

IRon-oRe deposits in the Philippine Islands became the subject of official record as early as 1664. Undoubtedly iron ore was known and recognized by the Filipinos long before the earliest Spanish records. It is even possible that the Filipino practice of smelting iron ore is, like the native copper smelting, older than the Spanish conquest of the islands. The first records have to do with the magnetite-hematite ores near the towns of Santa Inez and Bosoboso in Rizal Province, from 15 to 20 miles east of Manila. The magnetite-hematite ores of Bulacan were exploited in 1783. Similar ores near the town of Mambulao in Camarines Province yielded a number of specimens to be exhibited in Spain in 1834. With the exception, then, of the lateritic iron ores on the eastern coast of northern Surigao, the true nature of which was not recognized until 1914, the important iron-ore deposits of the Philippines had all been discovered before the islands came under the dominion of the United States. Indeed, in the Spanish documents relating to the history of iron mining are statements which, if their accuracy be not questioned, leave us in the Philippines today with much less iron ore than the Spaniards found. To quote, for example, a report submitted to the Superior Government in Spain in 1835 by one of its emissaries, Don Lorenzo Calvo: "The Philippine Islands, most excellent Sir, possess iron and exhibit it in nearly every known mineralogical combination, and in such abundance that the cordillera of the island of Luzon, from Montufar Point in San Bernardino Straits to Cape Bojeador, is composed of no other mineral than iron, its ranges, of the third order, being in content and structure totally iron of the best quality, the more valuable in that its combinations are such as to facilitate its fusion and to render its redaction to metal simple." Today, however, it is recognized that the iron-ore deposits in the Eastern Cordillera of Luzon constitute, not a continuous belt, but a series of widely separated deposits, including a half dozen orebodies within a distance of 10 miles in Bulacan Province, a single outcrop at Santa Inez, Rizal Province, farther south, and three deposits around

Jan 1, 1916

By George A. Grandy, D. W. Fuerstenau

Simulation of nonlinear grinding systems is discussed in the context of the size-discretized batch-grinding model. A linear approximation of environment-dependent (or nonlinear) selection functions is postulated for systems which exhibit feed grinding orders less than unity. For this, a convex linear combination of zero and first-order selection function forms is used to obtain an analytical solution that can be used for simulation. An example in which marked nonlinear behavior occurs is rod-mill grinding. Accordingly, a series of grinding experiments was carried out in a batch laboratory rod mill to test these techniques; agreement between experiment and the model was found to be very good. Recently, significant progress has been made in the simulation of linear grinding systems by using a population balance mathematical model. Herbst and Fuer-stenaul presented a parameter estimation scheme that can be used with the size-discretized batch-grinding model, and Gumtz and Fuerstenau3 have extended these techniques to the simulation of locked-cycle grinding. Grandy et aL." summarized the simulation of linear systems and noted important alternate solutions to the batch-grinding equation. Kelsall et a1.'-" discussed the dynamic simulation of linear batch grinding, as well as linear open and closed-circuit grinding. In all of these, the key word is linear, which certainly restricts the engineer trying to simulate a variety of grinding systems. This paper discusses an approach for the simulation of non-linear grinding systems, particularly those which exhibit grinding orders less than unity. Experimentally, dry rod-mill grinding is used to evaluate the technique presented. Batch Grinding Model The size-discretized batch-grinding model has been discussed in detail by Mika et al.'.' and by Herbst and Fuerstenau,' and therefore, will only be briefly developed here. The model is formulated by making a differential mass balance of each size fraction in such a manner that the equation parameters are precisely defined in terms of selection and breakage functions,' which can be either calculated'.' or estimated1 from experimental data. The model is phenomenological because it averages all stress-application events in the system and, therefore, does not distinguish the manner in which individual particles are stressed.' For this average environment, the resistance of all particles in a size fraction to breakage is defined by that size-frac-tion's selection function; and when fracture occurs from an average event, the breakage product size distribution is defined again by that size-fraction's breakage function. The model is deterministic and is derived in terms of a continuous time variable and a discretized size variable,' i.e., the n mass fractions associated with the n defined size intervals (see Table 1 for nomenclature).

Jan 1, 1971

By G. M. Ritcey, M. J. Slater, B. H. Lucas

The recovery of uranium from acid leach slurries by continuous ion exchange, or solvent extraction using sieve-plate pulse columns, is compared. Differences in processing costs are of prime concern and can be related to differences in the unit operations of the two methods, as well as the chemical and physical properties of the slurry. Parameters are defined for the operation of the solvent-in-pulp process and the design of the continuous ion exchange column. Pilot plant operating experience with both recovery systems is described, and an overall assessment of the relative costs is presented.

Jan 1, 1973

By Laurence Pellier

Electron microscopical studies were made of the effect of sensitization at 1200oF on a Type-.104 stainless steel with high carbon and low nitrogen and oxygen contents, after solution annealing and after cold working. The loci of the carbide precipitates in the early stages of sensitization were followed in dry stripped plastic replicas. Some observations were made by direct electron transmission on thinned films. Intragranular dislocations showed a high degree of stability through the annealing necessary to produce sensitization. I HE present work was undertaken to determine the effect of sensitization, at 1200°F, for 1/2 hr, on the electron microstructure of a Type-304 stainless steel with high carbon, and low nitrogen and oxygen contents, after solution annealing and after cold working. Many electron microscopical studies of sensitization of 18-8 stainless steels have already been made. Most of them utilized extraction replicas, from which the morphology and composition of the precipitated carbides could be established.'-" ry stripped replicas were seldom used for such studies, although it was demonstrated that they are applicable, in general, to EurveYs of the general microstructure of many alloys' and, in particular, to the observation of precipitated carbides in austenitic stainless steels.3

Jan 1, 1963

By C. L. Prokop

A laboratory investigation has been made of the effects of mud hydraulics upon the formation and erosion of mud filter cakes. The tests were conducted to simulate drilling conditions as nearly as possible. The formation of mud filter cake in a drilling well does not proceed at a uniform and unbroken rate. Instead, the rate of cake accumulation depends upon whether or not the mud is being circulated. If the mud column is quiescent, filter cake formation is a smooth function of the filtration characteristics of the system. If the mud is being circulated filter cake formation depends not only upon the filtration characteristics of the mud but also upon the erosive action of the flowing mud column Filter cakes formed during continuous mud circulation were observed to reach an equilibrium thickness after several hours' circulation. Mud circulation was maintained at a constant volumetric rate throughout each experiment. The fluid velocity at equilibrium cake thickness was dependent upon the thickness of the filter cake. Muds having exceptionally high water loss deposited thick filter cakes in spite of very high eroding velocities. The muds having good filtration characteristics deposited thin filter cakes at equilibrium circulating velocities well within tile range of those in a drilling well. It was observed that filter cakes deposited during stagnant filtration were quite difficult to erode by mud circulation. The - rate of crosion computed from the rate of filtrate accumulation after equilibrium cake thickness had been reached was in reasonable agreement with the rate of erosion obtained by direct observation. Continuous mud circulation usually caused the permeability of the filter cake to decrease with time. INTRODUCTION Many of the difficulties encountered during tile drilling of a well have been attributed to the loss of water from the mud and the attendant deposition of solids upon the walls of the hole. Past experience has shown that a reduction of the filtration rate of the drilling fluid eliminates or greatly reduces these difficulties. Definite filtration requirements, however, are hard to establish for a given set of conditions. This is due. in part, to the fact that the usual filtration test performed upon mud doe? not simulate well conditions as closely as desirable. The filtration characteristics of a mud are customarily determined by means of the standard low-pressure API wall-building tester.' In this instrument a filter cake is deposited upon a horizontal bed under a pressure differential of 100 psi. The rnud is quiescent during the filtration period. In actual practice. mud filtration occurs within a well under quite different conditions. One of the major differences is that mud flows upward across the filter bed as the filter cake forms. This undoubtedly produces a change in the filter cake which cannot be reflected in the results of the API test. The laboratory work described in this paper had as its primary objective a better understanding of the influence of mud circulation upon the thickness and ,characteristics of the filter cakes deposited under conditions similar to those existing in a drilling well. ANALYSIS OF PROBLEM Once a permeable formation is penetrated by the bit, filtrate from the mud flows into the formation. 'he mud solids plaster against the walls of the hole, forming a filter cake. If the mud column is stagnant, that is, if it is not being circulated. the filter cake will increase in thickness until the hole is filled. Prior to the time that the hole is filled, the thickness of filter cake existing at any given time will be a function of the filtration characteristics of the mud, the temperature, and the pressure differential. The effects of these variables have been investigated in the past for both flat bed filtration2'3 and for radial filtration.' When the mud is circulated in a hole in which a filter cake i. being deposited. some of the solids that would ordinarily deposit in the filter cake will be carried away by the eroding action of the mud. This will limit. filter cake thickness. Some work has been done to determine the effect of flow upon the filtration rate in a circulating mud system' but little work has been done upon the factors which determine the filter cake thickness existing in a circulating system. On first sight it would appear that the major factors controlling filter cake formation in a circulating system should be: 1. The rate of deposition of solids from the mud. 2. The erosive force that the flowing mud exerts upon the filter cake. 'A. The erodabilitv of the filter cake. 4. Any change in filter cake characteristics attributable to the scouring action of the mud. The rate at which solids are deposited from the mud will be controlled to a large degree by the filtration characteristics of the mud, the pressure differential. the temperature under

Jan 1, 1952

By J. M. Neilson

The occurrence of iron ore deposits in the State of Western Australia has been known at least since the 1930's,3 but the true significance of the deposits has only come to light within the past four years. Although they are widely distributed throughout the State, it is now known that more than 90% of the available iron ore reserves are located in the "Hamersley Iron Province". Western Australia may well contain the world's largest known reserves of iron ore. Recent reports place this reserve at 15 billion tons and an even higher figure may appear in the future. LOCATION, CULTURE AND COMMUNICATIONS It is difficult to comprehend the immense size of Western Australia (Fig. 1). The State occupies almost one million sq miles and it is more than 2000 miles from north to south. More specifically, it stretches from the 14th to the 35th parallel of latitude south. The Ophthalmia Region in the Hamersley Iron Province is barely halfway up the long dimension of the State. Nevertheless, the region is 800 miles north of Perth, a distance comparable to that from New York to Chicago or to that from Chicago to New Orleans. The Hamersley Iron Province (so named in 1963 to distinguish it from the Pilbara mineral district adjacent to it on the north) covers an area of approximately 30,000 sq miles in the northwestern part of the State. It extends in a roughly oval form from the Indian Ocean to the Gibson Desert of the interior, a distance of about 300 miles. With the exception of the small coastal towns of Onslow, Roebourne and Port Hedland and a few other communities such as the asbestos-mining town of Wittenoom, the region is very sparsely populated. Sheep and cattle stations are scattered thfough the region and these and the main towns are connected by truck tracks and a few main highways. Voice communication is almost entirely by the short-wave radio net operated by the Royal Flying Doctor

Jan 1, 1965

By Arthur R. Kommel, Robert F. Mehl, Gerhard Derge

The orientation relationships resulting from allotropic transformations and the formation of segregate structures in metals and alloys have been the subject of the eight earlier papers in this series'. A brief summary of orientation studies has also been given by Sachs2. A survey of these papers discloses that the factors that determine the orientation relationship of a precipitated phase to its parent solid solution, as well as the outward form and appearance of the new phase, are not completely understood. It is now evident that crystallographically analogous systems, as a rule, exhibit the same type of Widmanstatten figure and orientation relations, so that useful information is not to be expected from examination of a new alloy involving lattice combinations of which the orientation relationships are already known. Therefore, the determination of the relations existing between lattice types that have not already been studied seems to be the most promising mode of attack upon the problem; both of the systems reported in this paper represent new combinations of lattice types. A. The Mg-Mg2Sn System The magnesium-tin equilibrium diagram given by Hansen3 shows the phase Mg2Sn to be the only intermediate phase. The solid solubility of Sn in Mg decreases from 14.8 weight per cent at the eutectic temperature, 561' C., to 2.3 per cent at 450°, while no solid solubility of Mg in Mg2Sn has been observed. The crystal structur: of Mg is close-packed hexagonal with a0 = 3.202 A. and co = 5.199 A.4, while Mg2Sn is of the CaF2 type with a. = 6.78 A., with four molecules in a unit ce115,6. Alloys from two different sources have been used: (1) those supplied by the Dow Chemical Co., which contain 6 and 8 weight per cent Sn, and (2) those prepared in this laboratory, containing 8 and 13.5 per cent Sn. The latter were made from Dow high-purity Mg and Baker chemically

Jan 1, 1937

By W. T. Thom

RegaRding the elements necessarily involved .in working out a scientific scheme of classification, Stansfield and Sutherland, (94)† quoting Grout, (34) make the following statement: All bases (for a scientific classification) should be capable of quantitative determination, or be exactly related to some property capable of such a test, so that, if no natural groups are found, arbitrary lines may be drawn to limit the classes. The best basis for classification should involve inherent and fundamental qualities of the materials considered. Allied to this is the requirement that advantage should be taken of any natural grouping. As a further help in selection, the bases or tests should be easily applied, widely known, and have a wide range of values in the material classified. In order that we may apply the philosophy thus expressed, it is necessary for us to have clearly in mind both the reasons why coals differ and the specific purposes to be served by the classification to be devised. Coals differ because, as modern science has shown, coal beds are actually neither more nor less than buried and altered peat deposits, formed in remote geologic time. And as is generally known, such peat beds consisted of masses of partly macerated and decayed trees, shrubs, plants, mosses and/or algae, deposited under swamp or semiswamp conditions. It is therefore to be expected that coals will vary: 1. Because of differences in the parent vegetation, due either to evolutionary plant changes, as from the fernlike types of the Paleozoic to the coniferous and hardwood types of the late Mesozoic and Tertiary; or due to the differences in floral assemblages (growing at the same time) induced by differences in local environmental conditions. For example, moss, sedge, woody and other peats are today accumulating simultaneously in different bogs in North America. 2. Because of differences in the stage to which bacterial decay proceeded in the peat bed. Peats laid down in stagnant waters suffer

Jan 1, 1932

By R. E. Pollard

The National Bureau of Standards received, in August 1940, a number of samples of bridge wire taken from the cables of the General U. S. Grant suspension bridge over the Ohio River at Ports- mouth, Ohio. These cables were 7% in. in diameter under the wrapping and each was made up of 1458 ungalvanized wires of No. 8 gage in 3 parallel-wire strands. The choice of ungalvanized wire was based on the previous satisfactory performance of similar wires in other bridges over periods of 20 to 50 yr. of service(1).2 After about 12 yr. of service a number of breaks were discovered in the Portsmouth bridge cables, most of them at the anchor- age shoes, and they were replaced by cables made up of galvanized wire(2).

Jan 1, 1945

By F. B. WEEKS

I HAVE chosen for my subject a mining district which in an article published four years ago I referred to in the following words: "One of the un- usual anomalies of mining development and history is that a district having added thirty or more millions of wealth to a principal mining state, situated within four to six miles of two transcontinental railways and two auto highways, and within 150 miles of the most widely advertised part of the United States, should have been so completely lost sight of that probably not one mining man in ten can tell offhand where it is situated." But this district never was a dead one: it was only slumbering. During the past four months, day by day, it has been emerging from that state of slumber.

Jan 1, 1929

By G. Sachs

THE iron-rich iron-nickel alloys have at-tracted considerable academic interest in recent years. The carbon-free alloys are of minor practical importance, but they are Atomic per cent nickel FIG. I. FIG. 2. FIG, I.-HONDA'S AND MERICA's IRON-NICKEL DIAGRAM, FIG. 2.-MARSH'S IRON-NICKEL CONSTITU-TIONAL DIAGRAM. the base of many alloys with various out-standing properties. The iron-nickel alloys, therefore, have been investigated exten-sively regarding both their structures and their properties. The researches on these alloys up to 1938 have been collected and critically reviewed by J. S. Marsh,1 and will be discussed in some detail in the sec-tions of this paper dealing with specific subjects. These numerous investigations have not succeeded in establishing the equilibrium conditions in this system. Alloys containing more than a certain amount of nickel (8 to10 per cent Ni) undergo the allotropic transformation extremely sluggishly, both on heating and cooling, showing a large hysteresis,2 which is not dependent upon

Jan 1, 1940

By Frank E. Hauser, Philip R. Landon, John E. Dorn

The flow and fracture strengths of polycrystalline aggregates of high purity magnesium and a solid solution of aluminum in magnesium were determined as functions of temperature and grain size. Magnesium was found to obey two distinct fracture laws. Over the high temperature range, the fracture stress decreased with increasing test temperatures in a manner that closely paralleled the flow stress-temperature relationship. However, over the low temperature range, the fracture stress was independent of the test temperature though highly dependent on grain size, following the trend that is typical for the low temperature brittle fracturing of polycrystalline aggregates of body-centered-cubic and close-packed-hexagonal metals. Even at 78°K, however, plastic strains of 1 to 7 pet were obtained preceding onset of brittle fracturing. Over the brittle fracture range of temperatures, the fracture stress increased linearly with the reciprocal of the square root of the mean grain diameter, while over the entire range of temperatures investigated, the flow strength was observed to increase linearly with the reciprocal of the square root of the mean grain diameter. PREVIOUS investigations', 'have shown that deformation of coarse grained aggregates of high purity magnesium is interrupted by fracturing at very small strains. Such tendency toward brittle fracturing increased with increasing grain size and decreasing test temperature. In several respects, however, low temperature fracturing of magnesium appeared to differ from the truly brittle type exhibited by zinc, molybdenum, tungsten, and iron, so often characterized as a cleavage mode of fracturing. The absence of a well-defined cleavage mechanism for fracturing and the fact that some plastic deformation precedes fracturing might suggest that magnesium does not exhibit the same kind of brittle fracturing that is common to body-centered-cubic metals and to other close-packed-hexagonal metals. But, as will be shown, the low temperature fracture laws for magnesium are analogous to those that apply to iron, molybdenum, tungsten, and zinc in spite of differences in mechanisms and in plastic strains to fracture. In view of these observations. the low temperature fracturing of magnesium will also be called brittle fracturing. This, of course, does not imply that the brittle fracturing of metals is synonymous with the brittle fracturing of glass or other nonmetallics. Whereas the brittle fracturing of glass probably obeys Griffith's law, the low temperature brittle fracturing of metals arises from stresses induced by a series of dislocations piled up at an opaque grain boundary. Experimental Results All tests were made on tensile bars having gage sections that were 2 in. long and 0.375 or 0.25 in. wide. In order to develop a series of grain sizes, the

Jan 1, 1957

By Edwin S. Smith

Current research in the phenomenon of liquefaction has indicated some of the in situ material properties which should be considered in the planning of waste deposits. Practical experience in tailings disposal, however, must be combined with the results of theoretical and laboratory studies to develop the most economical and safe techniques against liquefaction failure. One of the many responsibilities of mining engineers and mill superintendents is providing for the safe and economic disposal of wastes (or tailings) that remain after a mineral has been extracted from an ore. The cost of disposal of these tailings exerts a considerable influence on the minimum grade of ore extracted from the mine. It varies to a great extent with each project and is dependent on many diverse factors, such as the local topographical, meteorological and seismological conditions together with the applicable water pollution laws of the area. The process used to extract a mineral from an ore determines the physical characteristics of the tailings and, thus, is one of the more important factors to be considered in the planning of disposal facilities. Today's trends in ore-processing operations complicate the problems of waste disposal: recently developed extraction methods result in the production of finer tailings, the use of lower grade ores produces greater volumes of wastes, and the enhanced land values in the vicinity of industrial plants preclude the former practice of spreading wastes laterally and force the expansion of waste deposits upwards to greater heights. The frequent occurrence of stability problems in waste deposits indicates that many mining organizations may not be employing current soil mechanics concepts and practices. One of the most spectacular, and often most disastrous, types of tailings dike failure is that resulting from liquefaction of the fine particles combined with a breach of the main retaining dike. TAILINGS DISPOSAL Since the many variations in site conditions, ore bodies and extraction processes dictate the general disposal procedures and mill superintendents incorporate special facilities to provide the most economical disposal method consistent with accepted safety standards, it is only natural that there are almost as many different disposal techniques as there are disposal areas. Methods used in the construction of retaining dikes include: (1) transporting granular material from an adjacent borrow pit and (2) mechanically segregating the total effluent and allowing the coarse fraction to form a retaining dike by hydraulic deposition. The location of a plant and the surrounding topography exert the greatest influence on the layout of tailings disposal facilities. Most of the above-ground waste deposits can be classified as side-hill, (Fig. 1,) cross-valley, (Fig. 2,) or stockpile deposits. Side-hill disposal areas are probably the most common type of layout because of the natural advantage of gravity flow, without the disadvantage of river diversion usually needed for tailings ponds formed behind cross-valley dikes. Stockpiles, which are placed on relatively level ground, require four retaining dikes and the effluent generally has to be pumped up into the disposal area. Changing production techniques or developments adjacent to disposal areas have produced variations or partial combinations of these three categories. In a series of articles, Lenhart describes many of the problems encountered in the disposal of tailings and certain innovations used to overcome them. He discusses weaknesses in design and layout and shows that disposal techniques are often learned the

Jan 1, 1970

By Frank J. Markewicz, William Lodding

Greensand, greensand marl, and green earth are names given to sediments rich in the bluish green to greenish black mineral known as glauconite by the mineralogist. The word glauconite is from the Greek word glaukos, meaning bluish green. The term "greensand" as a rock name for a glauconite-bearing sediment is more appropriate than "greensand marl," a term that has been doggedly perpetuated in the literature. Because of its potash and phosphate content, greensand was dug and marketed as a fertilizer and soil conditioner for more than 100 years. The advent of prepared fertilizers with adjustable nutrient ratios led to the decline of green- sand for agricultural application. The material has since been recognized for use in water treatment. Unfortunately, in spite of large reserves and worldwide distribution, the mineral has not been utilized to any significant commercial extent because no major application has been found for a substance with its chemical composition and properties. This lack is probably due to a paucity of research on its potential commercial application. Extraction of potash received considerable attention during and just after World War I. Because of relatively high extraction costs and generally low potash content (up to 8%), glauconite lost its appeal as a source of this commodity. Historical Background Greensand was used as a fertilizer in New Jersey in the latter part of the 1700s. During the early 1800s its use became more common; applications of up to 100 tons per acre were sometimes made, although recommendations for agricultural use suggested 20 to 50 tons per acre (Tedrow, 1957). Many crops, especially the forage type, were said to improve with greensand application; however, because of slow release of potash, large quantities were required. Certain greensands that contain sulfur and sulfide minerals are harmful to plant growth, and these were classified as "poison," "burning," or "black marls." The availability of higher-grade potash salts from other mineral sources, and the manufacture of prepared fertilizers, displaced the agricultural use of green- sand during the later 1800s. During the mid-1800s the domestic greensand industry, centered in a small section of the eastern United States, grossed more than $500,000 per year. Toward the end of the century, annual production had dwindled to less than $100,000. By 1910 there were only six or eight greensand producers, grossing less than $5000 (Tyler, 1934). There was a small revival in the industry during World War I because of the curtailment of foreign potash, especially from Germany. During the later 1940s and early 1950s greensand was again recommended as a food nutrient for plants and farm crops. Agronomic studies discussed its potential as a soil additive that gradually releases potash and many trace- element nutrients essential for plant growth (Tedrow, 1957). Greensand was sold with the idea that it would condition soil and absorb and hold water while its base-exchange properties would release trace elements. For a short time glauconite was utilized in certain parts of New Jersey as a binding additive in the brick industry, and in the 1800s for making green glass (Cook, 1868). In the early 1900s the base-exchange property of glauconite was recognized for water treatment, and the mineral gained acceptance as a water softener. Mansfield ( 1922) does not mention base-exchange; however, the base ex-

Jan 1, 1975