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By C. A. WARNER

IN all the meetings of the Petroleum Division, emphasis was placed on the essential importance, in the successful furtherance of our war effort, of efficiently producing, transporting, refining, and utilizing maximum quantities of crude oil and natural gas with the minimum expenditure of critical material. With representatives present from all branches of the petroleum industry, from all parts of the United States, the sessions were opened Tuesday morning with Commander Harry P. Stolz. U.S.N.R., Chairman of the Division, and A L. Haider as associate chairmen. From that time until the symposium on petroleum economics was closed Thursday afternoon papers of exceptional interest and importance were presented and discussed in a most frank and open manner.

Jan 1, 1943

By W. M. Albrecht, M. W. Mallett

The solubilities of hydrogen in titanium and several of its alloys were determined at 600 to 1000°C and pressures of 0.05 to 10µ of mercury. Solubility increases with increasing beta phase in the alloys. Factors found to affect degassing rates are specimen size and presence of thick surficial oxide. Removal of hydrogen by heating in vacuum and in flowing inert atmospheres was studied. Practical curves predicting minimum degassing times are presented. THE presence of hydrogen in titanium and titanium alloys has detrimental effects on the mechanical properties of the metal.'"," The hydrogen content of commercial titanium is sometimes of the order of 200 ppm by weight' and varies with alloy composition. As a consequence, titanium and some titanium alloys as normally processed are sometimes not ductile unless treated to lower the hydrogen content. The best known hydrogen-removal treatment is heating the material in a vacuum. The rate of removal (degassing) at a give temperature determines the duration of the treatment required to attain a satisfactory low hydrogen level.

Jan 1, 1959

By T. A. Rickard

Among the names which won a world-wide fame during the golden age of the early fifties, Bendigo and Ballarat were to Australia, what the Yuba and Grass Valley were to California. The map of Victoria did not for a long time show the name of old Bendigo;* for this first and more distinctive name was replaced with the more English Sandhurst, just as the alluvial diggings gave place to quartz mining. Towards the close of last pear, steps were taken to give back the old name, as associated with the early days of rich alluvium, and more suggestive than the application taken secondhand from an English military academy. History. The first discovery of gold? in this district, was made in the autumn of 1851 ; but there has never been any certainty as to the day or the man. At that time the country around Bendigo Creek was a part of the Ravenswootl sheep-run, and its resemblance to the Forest Creek district (now Castlemaine), induced the first prospecting. It was late in November when the "rush" broke out; the shepherds left their flocks; the sylvan solitudes were disturbed by * The name of Bendigo is said to have been derived from a hut-keeper on the Ravenswood sheep-run, who on account of his fondness for " fisticuffs " was nicknamed Bendigo, after the prize-fighter of that name. It is not aboriginal, as is often supposed, but Spanish ; and equivalent to our Benedict. There must always be some confusion between the two names of Sandhurst and Bendigo; the town, and with it the gold-field, having been three tinies named. Several other old familiar names have been likewise unfortunately replaced by second-hand English ones; so that an old digger talks of Forest Creek when he means the modern Castlemaine, Mt. Ida for Heathcote, Growler's Creek for Bright, etc. I shall use the names Sandhurst and Bendigo interchangeably. The first discovery of gold in Australia, was made by E. H.Hargraves, February 12, 1851, near Bathurst in New South Wales. In August of the same year the discovery at Buninyong, near Ballarat, inaugurated the first of a series of rushes to the Victoria gold-fields.

Jan 1, 1892

By R. Simon

The sources of energy dissipation for concentrated loadings on rock are considered in an attempt to account for the experimentally measured magnitude of the work required to break out a unit volume of rock from the free surface of an essentially semi-infinite medium. It is concluded that most of this work probably represents the elastic strain energy developed by the loading in a much larger volume of rock beneath the loaded region than the volume of the rock fragment broken out to the side of the loaded region. This strain energy is largely dissipated in the form of stress waves generated by the high rate of unloading produced by the propagating cracks. The energies associated with the formation of the new surfaces of the cracks and with the stress waves generated directly by the loading process are computed to be negligibly small. Possibilities for improving the utilization of energy to drill rod. subject to the geometrical limitations imposed by down-hole operation, are discussed. It is pointed out that any such possible improvements would probably have to be differential ones, since each rock configuration of more favorabIe loading geometry that can be created down the hole is accompanied by a complementary configuration of less favorable loading geometry. INTRODUCTION Dislodging each cubic inch of rock from the bottom of the hole by the action of a bit requires the expenditure of an amount of energy that varies from approximately 5,000 in.-lb to approximately 100,000 in.-lb, depending on the hardness of the rock, or, more technically, upon its fragmentation strength.1 In this paper we will discuss (I) why the energy expended in drilling is so large, (2) what happens to this energy upon completion of the drilling process, and (3) what are the possibilities for reducing the magnitude of the energy required to drill rock. DETERMINATION OF ROCK DRILLING ENERGY The volume of rock removed per unit time from the bottom of a hole of diameter D is evidently (7/4)D2R, where R is the rate of penetration of the bit. If P is the rate at which work is done by the bit on the rock at the bottom of the hole, the energy required to break out a unit volume of rock is given by: Ev =(4/p) P/D2R............(i) For rotary drilling, of either the rolling-cone or drag-bit varicty, P = 2pLN, where L is the torque resistance to rotation at the bottom of the hole and N is the rate of rotation of the bit. L is essentially the same as the torque measured at the rotary table only when drilling in shallow holes. The energies expended in rotating the drill string against the frictional resistance of the walls of the hole and and against the viscous drag of the drilling fluid are extraneous to the subject under consideration, although these may be much greater in magnitude than E, when drilling in a deep hole. For percussion drilling, P = fE where f is the percussion frequency and E is the work done on the rock per impact. The latter quantity can be both computed and measured for a percussion drilling machine. 2 (Under satisfactory drilling conditions, defined in terms of ranges of numerical values of certain dimensionless parameters, E is only 30 to 50 per cent less than the impact energy of the striker.2) Alternatively, E, may be measured directly by dropping chisels shaped like bit edges, backed by rigid weights, onto the surfaces of laboratory rock samples of effectively semi-infinite extent. Under these circumstances, essentially all of the impact energy is converted to work done on the rock, and the relationships among volume of rock broken out, chisel shape, impact energy and indexing distances can be obtained.3 The values of the energy required to break out a unit volume of rock under favorable circumstances are substantially in agreement for rotary drilling, percussion drilling and drop testing at atmospheric pressure. The energy per unit volume is a quantity of the order of magnitude of roughly twice the com-pressive strength of the rock as measured by a uniaxial loading test. The phrase "order of magnitude" in this paper means from about 1/3 as much to 3 times as much; i.e., the energy per unit volume may range from roughly the same up to several times

By John A. THOMPSON, Pazcl D. Torrey, Frank Breayster

DISCOVERY of natural gas in the Dundee field of New York in February, 1930, and the subsequent discovery in Tioga in September of that year, focused the attention of the natural-gas industry on the enormous possibilities of production and distribution in - the most populous area of the United States-New York and New England. Prior to 1926 the natural-gas industry in New York State had settled into a definite and limited policy, with the distributing companies controlling the output from its discovery to the ultimate consumer. Production amounted to between G and 7 thousand mil- lion cubic feet a year, with another 10,000 million feet imported from Pennsylvania for distribution in New York State. This gas was primarily from the Medina sand stone in. the western part of the state.

Jan 1, 1932

By Thos Stroup

RECENT contributions to the literature relating to the problems of coal mine management have discussed the pros, and cons of unionism among the miners as bearing upon the immediate problems of the industry, but have devoted singularly little thought to the underlying causes, and the fundamental reasons. for the remarkable growth of union sentiment among the miners, a growth paralleled only in the case of the railroad workers. It is all very well to revile their organization, its obvious stupidity and stubbornness, its multitude of economic and social crimes, but it is also well to realize that there have been deep-seated causes for all these things, causes that, while operating in all industries and amongst all workers, have in none of them found the optimum conditions for development such as exist in the coal mining industry. The rise of the United Mine Workers of America to a position of importance in the industry synchronizes roughly with the introduction of short-time operation; of course seasonal shutdowns and slow-time working have always been evident in our bituminous fields, but these evils have grown steadily worse since 1895 and the U. M. W. of A. has grown steadily stronger; yet short-time operation alone cannot account for this tremendous growth for, witness the signal failures that have always attended the attempts to organize the harvest workers, the fruit packers and other highly seasonal workers.

Jan 9, 1923

By Selma Hermann

For the past century, the so-called aluminum bronzes have been assuming a role of ever-increasing importance in the metallurgical field. The last quarter of that century has marked many efforts to find alloying elements that would alleviate some of the undesirable qualities of the aluminum bronzes-for example, the heterogeneity of the alpha solid solution and the extreme hardness of the beta. Much of this work, however, has been rather haphazard-compositions and heat treatment are usually so much at variance as to make comparison impossible. It is the object of this research to study the effect of certain percentages of common alloying elements on aluminum bronzes of analogous compositions and heat treatments. It is hoped that the material gathered here will at least serve as a basis for further systematic study.

Jan 1, 1930

E. T. Dumble, Houston, Texas (communication to the Secretary) : During the field-season of 1890 I had occasion to examine some of the salines of eastern Texas. As the result of my stridy of them I came to the conclusion that, together with the oil of Hardin county (since extended to Beaumont by the work of Capt. Lucas) and the rock-salt and gypsum-deposits of the coast country, extending southward to the Rio Grande, these were simply a continuation of similar deposits in Louisiana described by Hilgard, Hopkins, and others; and I recommended the sinking of wells wberever they were found.

Jan 1, 1902

By R. Floyd Farris

A THOROUGH knowledge of the behavior of cement slurries under elevated tempera-tures and pressures is necessary in order to solve properly the many problems pre-sented in deep-well cementing operations. In the earlier days of the petroleum indus-try the depths of wells were shallow as compared to those of today, and the subsurface temperatures and pressures were not of sufficient magnitude to affect seriously the problem of proper control of cement-slurry properties. Today, however, the search for new reserves has extended drilling to such depths that bottom-hole temperatures of more than 200°F. and bottom-hole pressures of 3000 to 5000 lb. are not uncommon. Moreover, there is every indication that within the next few years wells will be drilled to even greater depths and bottom-hole temperatures and pressures will be correspondingly higher than those with which we are concerned today. It has been realized for some time that the behavior of cement slurries at high temperatures and pressures might be very different from that at atmospheric tempera-ture-pressure conditions, but while the temperature effects have been investigated with a reasonable degree of thoroughness, the pressure effects have received little public attention. While the trend toward deeper drilling may make changes in cementing technique and the choice of cements imperative, it was the purpose of this investigation to consider factors having a bearing on the latter, only secondary consideration being given, for the present, to details of tech-nique and equipment for oil-field use. More specifically, the purpose of this work was to consider the effect of temperature and pressure upon the behavior of cement slurries.

Jan 1, 1940

By N. Lilienberg

The success of European experiments in melting iron and steel with gases resulting from the decomposition of steam by incandescent coal, has encouraged me to design, with the valuable assistance of Mr. George S. Dwight, a plan for producing and burning these gases in a manner economical and efficient for metallurgical purposes. That this direction is the right one, is demonstrated by the repeated efforts made in practice, to introduce as much steam as possible with the blast in ordinary producers, thus displacing a certain amount of nitrogen. Such attempts, however, must always be limited by the cooling influence of the steam. The accompanying drawings represent the producers and the steel-melting furnace, arranged according to our first ideas which may be susceptible of improvement in details when put into practical

Jan 1, 1885

By R. B. Woodworth

INTRODUCTION IN the sinking of bore holes, there are but two fundamental operations -drilling and hoisting,-which determine in the main the character of drilling mechanism and structures. There are endless ramifications, however, in the execution of these fundamental operations, according to the purposes for which the bore holes are drilled, their maintenance after completion, the protection and convenience of workmen, etc. The three main lines of use for bore holes are in mineral exploration, the sinking of water and salt wells, and the exploitation of petroleum and natural gas. This paper has to do more especially with the last. Here again there are many divergences. Wells may be drilled by either the percussive, the hydraulic, or the abrasive method. Finally, each of these methods, as applied by drillers of diverse nationalities, has followed somewhat different lines of development. The American system of cable-tool drilling has perhaps had the widest application; the hydraulic rotary is also in extensive use; but the Canadian system, the Galician system, and the Russian free-fall system all have their points of recognized merit and are preferred by operators accustomed to their use. These differences in drilling procedure, which rest ultimately on essential variations in geological conditions, are reflected in the chilling structures as well as in the drilling mechanism. The purpose of the present paper is to record those stages in the development of the application of steel to the construction of drilling mechanism and structures with which the writer has been intimately associated, and to contribute to the history of the art of drilling other data acquired in the course of his personal investigations. It is necessarily limited by reason of space to American practice, with especial reference, therefore, to the cable-tool system and the hydraulic rotary method of drilling wells for oil and gas.

Jan 11, 1915

By Wilson Lundy

THE history of the production of sulfur from salt domes in Louisiana and Texas originated with the operations of the Union Sulphur Co. at Sulphur, La., followed by the Freeport Sulphur Co. at Bryanmound, Tex. Including the present development of Grande Ecaille by the Free-port Sulphur Co., which constitutes the tenth dome to be equipped for the production of sulfur in the Gulf Coast, less than 10 per cent of all the known domes have proved to contain sulfur in commercial quantities. The Grande Ecaille salt dome is in the tidal marsh of the Mississippi River delta in Plaquemines Parish, Louisiana. It is 10 miles southwest of the right descending bank of the river approximately 45 miles below the city of New Orleans and is within 4 miles of the shore line of the Gulf of Mexico.

Jan 1, 1934

To Americans, Alaska occupies a unique position, both geographically and historically. The only integral portion of the United States lying in the sub-Arctic and Arctic regions of the Earth, the early remoteness and climatic conditions effectively combined to impede the economic development of this area. Although Alaska has been a part of our Nation since 1867, its mining industry is still at that stage of development which characterized the West 100 years ago when miners concentrated on high-grade lodes and rich placer deposits. Since World War II, however, there has been a noticeable increase of interest in the raw materials of the North. This concern has been most noticeable in Canada, Scandinavia and Russia, but it has been, and is being shown in Alaska. To the American mining industry, the potential importance of this State can be summed up by the question, "Can Alaskan mining compete successfully with those of other states and countries?" The answer revolves about the vital factors of geography, economics, and the political turmoil of the World. These aspects are among those discussed on the following pages in a series of articles by Alaskans and non-Alaskans alike. We invite you to read "Alaska: Regional Report."

Jan 12, 1961

By Matthew J. Hrebar

SINCE the first installation in 1936, the use of rubber-tired equipment for secondary mine haulage has increased rapidly. From August 1936 to January 1944, approximately 750 rubber-tired units were placed in operation. Of these, 650 units were installed after January 1940. During the year 1941, it per cent of the mobile loaded bituminous tonnage was hauled by rubber-tired equipment. This percentage increased to about 20 per cent during 1943. The first rubber-tired units were battery-powered tractor-trailer types. In the year 1938 the battery-powered self-contained car was introduced. In 1939, the cable-powered self-contained car made its appearance. These self-contained units are our modern "shuttle cars." By the end of 1941, approximately 15 per cent of the shuttle cars in operation were cable-powered. Installations made during 1942 and 1943 increased the proportion of cable-powered cars to about 40 per cent of the total number of shuttle cars in use. There is a marked trend toward cable-powered cars, although one need not make many trips to mines where both types are used to discover that opinions are highly controversial as to the relative advantages and field of use of each type. It is natural for mining engineers in the coal-mining industry to have diversified opinions regarding the use and application of coal-mining machinery. Coal mining is not a standardized industry; natural conditions vary from mine to mine. However, it is surprising how many operations in scattered fields arrive at the same conclusions and adopt similar methods. This happens not so much through cooperation and exchange of ideas as through hard, costly experimentation, involving months of low production and relatively high costs. What then, are the reasons for increased use of cable cars? Could it be that present scarcity of materials is forcing their use? True, battery cars require considerably more auxiliary equipment, but during 1942 it was no more difficult to obtain than shuttle-car cable. Furthermore, the trend toward cable cars started before curtailments on mining equipment took effect. Undoubtedly, cable-reel shuttle cars were introduced to produce coal at a lower cost by simplifying trackless mining through the elimination of auxiliary equipment, and by reducing the first cost on equipment. The theory of cable-powered shuttle cars is well based, as can be proved by successful operations. Many operators have weighed the advantages and disadvantages of each type carefully before choosing the type most suitable to their operation. Others have taken much for granted and accepted one or the other without much thought. At many small operations, low first cost is apt to be the deciding factor. One large company, with considerable experience in the use of battery locomotives, preferred to use cable cars even though it was neces¬sary to reduce the section voltage from

Jan 1, 1944

By Michael Tenenbaum

THE importance of semikilled steel as a high tonnage grade has long been recognized. The increasing severity of the applications for which semikilled steel is used makes it desirable to obtain further information regarding the features of open hearth practice and ingot structure that can affect steel performance in subsequent rolling and fabricating operations. Accordingly, an investigation is being carried out studying the structure of various types of semikilled steel ingots. This paper reviews some of the observations made and information gathered in this investigation. By definition, semikilled steel may be considered to include all nonrimming steels in which the natural shrinkage occurring during ingot solidification is offset to an appreciable degree by gas formation. Accordingly, this type of steel includes the entire range intermediate between rimmed and fully killed steel. The resultant ingot structures range from those of steels that have been capped to suppress a weak rimming action to those steels that have been killed in the furnace or ladle to the extent that no mold deoxidizer is required. A survey reported to the 1946 AIME Open Hearth Conference' reviewed the practices being used at 28 major plants for the deoxidation of semikilled steel. It was found that most plants divide the deoxidizing additions between the ladle and the mold many of the plants adding only minor amounts of deoxidizer to the bath or none at all. Silicon, aluminum and titanium were the only elements used for ladle and mold deoxidation. Mold deoxidizers were added as capping additions or as uniformly fed additions. Several practices were reported in which the steel was deoxidized in the ladle to the extent that little or no mold deoxidation was needed. No reference was made to grades capped by using special mold designs or special closures over the top of molds. Accordingly, specific examples of this type of practice will not be considered in this paper. It appeared from this survey of deoxidation practice that semikilled steel can be divided into three types, namely, capped semikilled, in which aluminum is added near the end of pour or after shut-off, intermediate semikilled steels, in which aluminum is fed uniformly throughout the pour, and semikilled steels requiring no mold deoxidation. In an attempt to cover the ingot structures obtained by the range of practices reported in the preceding survey, three series of experimental heats were made using increasing amounts of aluminum, silicon and titanium for ladle deoxidizers. The ladle deoxidizers were added as stick aluminum, 50 pct ferrosilicon and 20 pct ferrotitanium (4 pct carbon), respectively. Two methods of studying ingot structures were used. Ingots were removed from production, burned longitudinally and machined to allow observation of the central pipe and coarse blowholes. During the machining operation much of the finely porous subsurface structure was obliterated. Accordingly, observations were also made

Jan 1, 1947

By W. W. Anderson, D. G. Girton

The photoluminescence of Pr, Nd, Ho, Er, Tm, and Yb in CdS, and Ho, Er, Tm, and Yb in ZnSe has been observed from crystals Prepared by diffusion using rare earth metals and an excess chalcogen pressure. For a given temperature, time, and chalcogen pressure the spectral characteristics were very reproducible from run to run, and the emission intensity for Nd, Er, and Yb in CdS was as high or higher than the best vapor phase doped crystals we have grown. For a few rare earths it was found that certain conditions of diffusion tend to yield optimum rare earth emission intensity with respect to the background lattice emission. Photoluminescence measwements of Yb in CdS as a function of depth gave a profile which was neither a Gaussian nor complementary error function. Part of the profile appears to arise from a fast component of the diffusion and the other part from a slow diffusing component. At 960°C and 33 atm S pressure, a com -plimentary error function approximation of the slow diffusing component gave a diffusion coefficient of D = 1.3 x 10-9 sq cm per sec. MOST of the studies of emission from rare earth ions in II-VI compounds have been reported on crystals doped during growth,1,2 although Kingsley and Aven prepared ZnSe:Er by diffusion for paramagnetic resonance and fluorescence studies. Pappalardo and Dietz prepared CdS:Yb by diffusion, but they made optical absorption measurements., We know of no study on the properties of rare earth diffusion in the II-VI compounds. To date we have diffused Pr, Nd, Ho, Er, Tm, and Yb into CdS, and Ho, Er, Tm, and Yb into ZnSe and observed the rare earth emission spectra. For a given temperature and chalcogen pressure, the emission characteristics are very reproducible from run to run and for Yb, Nd, and Er in CdS, as good as the best crystals we had prepared by doping during vapor phase growth.2 The emission of Pr, Ho, and Tm has been observed in CdS prepared by diffusion for the first time. Previous attempts2 to prepare these later three materials by vapor phase growth were unsuccessful. The problem of obtaining reproducible characteristics in II-VI semiconductor compound work is well known.5 Not only is it difficult to reproduce results from one laboratory to another but it is sometimes difficult to reproduce results from one growth run to another under ostensibly identical conditions within one laboratory. This situation has been particularly bothersome in research on the luminescence of rare earth activated ZnS1 and Cds2. Crystals from one vapor phase growth run would show very strong rare earth line emission while crystals from a nearly identical run would show no rare earth emission. It was also observed on occasion that the intensity of the rare earth emission was not constant over the entire volume of a single crystal. MATERIAL PREPARATION AND INSTRUMENTATION Vapor phase grown boules of CdS were supplied by Dow Corning. This material was characterized by a free electron concentration of n - 3.5 x 1015 cm-3 and Hall mobility of 350 sq cm per v sec at room temperature. There were microscopic voids and decorated precipitates in some samples. The precipitates annealed out at diffusion temperatures but the voids remained. Single crystal rectangular samples of mm dimensions were sawed from the boules. The ZnSe was polycrystalline, UHP grade from Eagle-Picher. Poly-crystalline samples were sawed from the ingots. The samples were lapped, polished on one side, etched in a solution of 0.5 M K2Cr2O7 in 16 N H2SO4, and thoroughly washed in distilled water. A sample, excess sulfur (or selenium), and 5 mg of rare earth metal (turnings) were sealed in a 3.6 cm3 quartz ampoule at about 2 X 10-5 torr. The high chalcogen pressure used (1 to 30 atm) prevented thermal etching of the crystals and affected the diffusivity and solubility of the rare earth ions in the crystal lattice. For meaningful or reproducible results, it is thus necessary to specify the vapor pressure at which the diffusion was carried out. It is assumed that a negligible amount of the chalcogen was used in the formation of rare earth sulfides or selenides Our sulfur vapor pressure calculations are based on data assuming S2, S6, and S, molecules only in which case the equilibrium constants are given by6 where the pressures are expressed in torr. Selenium vapor consists of a mixture of Se2, Se4, Se6, and Se6 molecules. The selenium vapor pressure was calculated using equilibrium constants given by The status of the rare earth source during diffusion is unknown, i.e., the partial pressures of the rare earth metal and of the rare earth chalcogenides has not been determined. All emission spectra were recorded at 77°K on a Perkin-Elmer model 98-G spectrometer using a 640 line per mm grating. No correction was made for the spectrometer and detector spectral sensitivity. Excitation was by means of an XBO 1600 w xenon arc

Jan 1, 1970

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 Jill Dill Pasteris

Several mineralogical prospecting techniques are used in diamond exploration. Most are concerned with identifying indicator minerals such as pyrope garnet and magnesian ilmenite, which are derived from mantle xenoliths hosted by kimberlites. The first goal of such prospecting is to locate kimberlite intrusions; the second goal is to identify the diamond-bearing kimberlites. Explorationists have worked much less on the indigenous kimberlite phases. The kimberlitic opaque oxides, ilmenite and particularly spinels, promise to be useful in discriminating between intrusion episodes in identified kimberlites, and perhaps in the evaluation and prediction of diamond grades. Several petrologists have showed that spinel compositions and zoning patterns are specific to certain intrusive facies in South African and Canadian kimberlites. Careful evaluation may indicate a correlation between spinel parameters and diamond content.

Jan 1, 1984

By J. H. Craig

As a result of information that the Navy Department was questioning the advisability of raising the maximum allowable exposure temperature for zinc-coated steel parts from 500 to 750 F., it was decided to make a series of high temperature tension tests on several types of uncoated and zinc-coated steels. The objective was to determine at what temperature intergranular penetration of galvanized steel by zinc might take place under conditions of rapidly applied stress and temperature. Tests were conducted in the range from room temperature to 1400 F. In this range, low-carbon and high-carbon steels did not suffer any adverse effects due to zinc coatings. In fact, at 1400 F. the zinc coatings appeared to have a beneficial effect. In stainless steel, the coating had no effect up to 1000 F. Above this temperature, the zinc coating appeared to cause a marked loss in ductility and a less pronounced loss in strength. There was no visible evidence of zinc penetration of the stainless steel structure, but it was assumed that this was the cause of the adverse effect.

Jan 1, 1945

By H. W. Camp

ALTHOUGH the situation in the oil industry during the past year has. not been conducive to large expenditures for development and research, there is little indication that such expenditures have been curtailed. While few outstanding achievements have been reported, considerable progress has been made in the development of new products and the adaptation of petroleum derivatives to new uses. The most important question facing the refiner today is the anti-knock quality of his gasoline. This year has seen the widespread adoption of the term "octane number" as a measure for anti-knock values, and in the latter months of the year the public has been made acutely aware of this condition through competitive advertising. Gaso-line is no longer priced on volatility and gravity alone, but on octane number as well; and premiums are being paid for material of relatively high octane rating. The situation has grown more and more competitive and has forced refiners continually to raise the octane rating of their regular and com-petitive grades, and at this writing the same situation exists for premium grades which have possessed relatively high anti-knock properties for some time. Straight-run gasoline produced from paraffin-base or semiparaffin-base crudes has an inherently low anti-knock value, and in order to convert this material to a higher quality it has been found necessary to crack an increasing percentage of the crude oil charge. By completely cracking the heavier portions of the crude, and blending back with the straight-run gasoline, it has been possible to produce an average of 63 to 65 octane number gasoline' on average Mid-Continent crude. This operation carried to the fullest extent does not suffice, however, and the recent and rapid development of the so-called "re-forming unit," has resulted. The straight-run gasoline fraction is cut into two parts: a light, low boiling point gasoline; and a heavy gasoline or naphtha. The latter containing the low anti-knock portions of the gasoline, is sent through a re-forming unit and subjected either to high temperature ,or pressure, or both, which materially increases its octane number. On average Mid-Continent the blend of low boiling point straight-run,

Jan 1, 1932