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By G. Rowan, M. W. Clegg

Approximate analytical solutions for non-Darcy radial gas flow are derived for bounded and infinite reservoirs producing at either constant rate or constant pressure. These analytical solutions are compared with published results for non-Darcy flow obtained on digital and analogue computers, and the agreement is show to be very good. Some observations on the interpretation of gas well tests are made. INTRODUCTION The flow of gases in porous media is a problem that has been the subject of much study in recent years [l - 71 , and many methods have been proposed for solving the non-linear equations associated with it. The assumption that the flow satisfies Darcy's Law It has been observed, however, that the linear relationship between the flow rate and pressure gradient is only approximately valid even at low flow rates, and that as the flow rate increases the deviations from linearity also increase. It has been suggested by a number of authors that Darcy's Law should be replaced by a quadratic flow law of the form This form of equation was first suggested by Forchheimer [9] and, later, Katz and Cornell [10], and Irmay [lll, developed a similar equation. Houpeurt [12] derived this form of equation using the concept of an idealised pore system in which each channel consists of sequences of truncated cones giving rise to successive restrictive orifices along the channel. This type of representation leads to a quadratic flow law of type [4], for all fluids, but it is found that the quadratic term is only significant in the case of gas flow. The methods of Houpeurt for solving gas flow problems will be discussed further in another section of this paper. Solutions of the non-linear equation for Darcy gas flow 121 may be classified as either computer (digital and analogue), or approximate analytical ones. The former include the well-known solutions of Bruce et al. [13], and Aronofsky and Jenkins [14] , but the latter solutions, apart from the simple linearisation of equation (2) to yield a diffusion equation in p2 , are not so well-known. Amongst these approximate analytical solutions should be mentioned the work of Barenblatt [IS], who has applied the techniques of dimensional analysis to obtain similarity solution to a large class of non-linear equations; also, a number of Russian authors, including Barenblatt [16] , Kim [17] and others, who have used the method of moments for obtain-

Jan 1, 1965

During 1940, the Bahrein Island field produced a total of 7,073,919 bbl. of crude oil- an average of 19,328 bbl. per day. This is a decline of 514,635 bbl. from the I939 production of 7,588,554 bbl. At the end of 1940, there were 70 producing wells.

Jan 1, 1941

During 1940, the Bahrein Island field produced a total of 7,073,919 bbl. of crude oil- an average of 19,328 bbl. per day. This is a decline of 514,635 bbl. from the I939 production of 7,588,554 bbl. At the end of 1940, there were 70 producing wells.

Jan 1, 1941

By James W. Dally, William L. Fourney, Anders Ladegaard Peterson

For the past 3 years, the authors have been conducting research sponsored by the National Science Foundation (RANN) to improve the process of excavation by drilling and blasting. The approach followed has been experimental where the development of stress waves and fractures initiated at the bore hole have been investigated in order to obtain a complete understanding of the dynamic fracture process. The second step in the approach has been to introduce modifications in the drill and blast procedure which will permit closer control of the fracture process. The laboratory investigations involve high speed photography where the dynamic fracture process is recorded with a Cranz-Schardin 1, 2 multiple-spark camera. The camera is equipped with 16 spark gaps which are pulsed at 25 K volts to produce an intense but very short (0.5 sec) flash of light. The camera is capable of recording 16 photographs of a dynamic event at framing rates which can be varied from 30,000 to 1,500,000 frames per second. The exposure time is sufficiently short to stop motion associated with detonating explosive charges and to make visible the details of the fracture process at a bore hose. The bore hole in a massive intact rock formation is modelled with a two dimensional plate containing a circular hole to represent the bore hole. The model material employed is a transparent polyester known commercially as Homalite 100.* This polymeric material is extremely brittle as evidenced by its extremely low fracture toughness of [ ]. The fracture toughness is a measure of the ability of a material to resist the propagation of flaws or small cracks. In comparison, Schmidt3 has recently measured the fracture toughness of Salem limestone and determined [ ]. Thus, the Homalite 100 should closely model the brittle nature of rock where fractures occur at small flaws and propagate without any apparent plastic deformation. Homalite 100 is also birefringent, which indicates that it becomes optically anisotropic when subjected to either static or dynamic loads. Circularly polarized light is transmitted through the loaded Homalite 100 model in a polariscope4 and the birefringence produces an optical interference pattern which is called a fringe pattern. For dynamic photoelasticity, the multiple-spark camera is equipped with polaroid filters to produce the circularly polarized light required to generate the photoelastic fringe patterns. An example of a singlespark frame showing a fringe pattern from a typical experiment is presented in [Fig. 1]. The photograph was taken 0.000072 sec (72 sec) after the detonation of the explosive charge. The circular fringes are due to the outgoing dilatational or P type stress wave and travel with a velocity of 85,000 in. per sec (2260 m/sec) in the Homalite 100. The P wave is followed by a second lower velocity stress wave known as the shear or S type wave which propagates at a velocity of 49,000 in. per sec (1245 m/sec). In the local neighborhood of the bore hole, several radial cracks are visible. These cracks propagate at essentially a constant velocity of 15,000 in. per sec (380 m/sec) prior to arrest. The fringes about the crack tips and in the local region of the bore hole are primarily due to the residual gases contained in the bore hole after the explosive charge was detonated. Sixteen frames similar to this one are recorded during the experiment to give full field visualization of the dynamic event at 16 discrete times over its duration. The fringe order number N is related to the difference in the principal stresses of and 02 according to a stress optic law4: [ ] where f0 = material fringe value, and h = model thickness. The wholefield dynamic-fringe patterns provide a basis for simultaneously observing the interaction between propagating cracks and the stresses which drive these cracks. Fracture Control Experiments Improvements in the efficiency of the drill and blast procedures must involve close control of the fracture process following the detonation of an explosive charge in a bore hole. By control it is implied that the number of cracks initiated and the location of each crack on the wall of the bore hole can be specified. Control also, involves orienting each crack and maintaining the crack path and velocity until the specified crack length is achieved. If the entire fracture process can be controlled, then rounds can be designed to optimize volume removed. fragment size and minimize costs. One area of blasting where fracture control is vitally important is in underground excavation where the strength and stability of the rock walls must be maintained and smoothness and precision of the walls must be achieved. The smooth blasting method is one of the most commonly employed procedures for achieving some degree of fracture control. In smooth blasting, the central region of material is first removed, and then the final row of closely spaced undercharged or cushioned holes are fired to remove the final volume and produce a smooth wall. In some instances, unloaded or dummy holes between the loaded holes are recommended to guide the fracture plane. This investigation pertained to an evaluation of 3 features of the smooth blasting process. These included (a) the effect of stress reinforcement on fracture by simultaneously firing 2 charges; (b) the influence of a dummy hole on control of the fracture planes between 2 simultaneously fired charge holes; and (c) the influence of dummy hole spacing on fracture plane control.

Jan 1, 1979

By S. Shapiro, G. Krauss

The strutural and cr~stallo~aphic features of the plates of austenite produced by the martensite to aus-tenite or reverse martensitic tramformation have been determined in an Fe-33 wt pct Ni alloy. Micro-focus X-ray techniques and single-surface trace analysis 072 bulk samples yielded two distinct habit planes, (0.174, 0.309, 0.~35)~ and (0.375, 0.545, 0.749jM. The former plane uas the one predorninantly observed and its existence was verified by transn~ission electron microscopy. The orientation relation-ship between the reversed austenite and the parent martensite was approximately the same as the Nishiyamna and other relationships reported for the direct tramformation. Replica and thin-joil obser-vations show that both high densities of tangled dis-locations and occasional twins constitute the fine structure of the reversed austenite. Application of the phenomenological theory to a variant of the predominant habit plane defines an irrational plane and direction for the second shear in accordance with the comnplexity of the fine structure. The shear accompanying the reverse martensitic transformation is at least 0.51, the maximnum value of- the tangent oJ the tilt angle measured on surface replicas. A mechanism relating the fine transformation twins in martensite to the nucleation of reversed austenite of the predominant habit is proposed. The reversal of Fe-Ni martensite takes place both at the edges of martensite plates and in a piecewise fashion within them.' The shear-type nature of the reverse transformation is verified by the surface relief which accompanies both edge-type reversal2 and the fragmentation of plates of martensite' as a result of rapid heating above the A, (austenite start temperature). The orientation relationship between the edge-type reversal product and the parent martensite, as determined by transmission electron microscopy, is reported to be within 4 deg of either the Kurdyumov-Sachs or Nishiyama relationships,' but there is no work at present in the literature relating to the crystallography of the platelike reversed austenite. The fine structure of reversed austenite after heating to 50°C above the Af is reported4 to be composed primarily of tangled and jogged dislocations in concentrations up to 10" per sq cm. A replica investigation of partially reversed Fe-Ni martensites5 corroborates the increase in dislocation density following reversal and presents indications of other possible modes of fine structure. This paper reports on an investigation performed to examine in detail the morphology and crystallography of the plates of reversed austenite and the shear which accompanies their formation in a matrix of Fe-Ni martensite. EXPERIMENTAL PROCEDURE Discs of a high-purity Fe-32.9 wt pct Ni single crystal served as the starting material. The single crystal had been produced in the course of an earlier investigation6 and the carbon content was determined at the time to be 0.006 wt pct. The M,, and the A,, were respectively -120" and 300°C. Partial transformation to martensite was performed at -125°C and reversal of some of the martensite was accomplished by heating in the temperature range 340" to 355°C. Most samples were heated to the reversal temperature by immersion' in a salt bath for 2 min. For surface-relief studies some polished and etched Samples were heated in a tube furnace for ten min in a hydrogen atmosphere maintained over the samples throughout the heating and cooling cycles. Samples were prepared for metallographic examination by electropolishing and etching with an HC1-HNOs-H20 et~hant.~ On one of the surface-relief samples two sets of fiducial scratches were placed on the etched sample by drawing it over a slurry of 0.06 p alumina on a "microclothJ'. The orientations of individual plates of martensite were determined by X-ray analysis. A Rigaku-Denki microbeam X-ray generator in conjunction with a Micro-Laue camera with facility for precision location of the sample in front of the beam was employed for this purpose. The collimator size was 30 p and the specimen to film distance was 5 mm. The Laue photograms were enlarged to an equivalent 3-cm specimen to film distance for analysis. The orientation of each of the plates of martensite was compared to that of the parent austenite and the relationship be -tween the two phases was, in all cases, within a few degrees of those predicted for the direct transformation. The orientation relationship between one of the larger plates of reversed austenite and its parent martensite was determined in a similar manner. The habit plane of the islands of reversed austenite in the X-rayed plates of martensite was determined by a single-surface trace analysis. Each reversal island had with the parent phase one comparatively straight boundary which was presumed to represent the habit plane trace. The pole locus technique7 was applied to traces from six different plates of martensite to determine the indices of the habit plane. A 40-cm stereographic net was employed for this analysis The morphology and fine structure of the reversed austenite were studied by electron microscopy of pre-shadowed direct carbon replicas,5 and the macroscopic shear was evaluated by a two-stage replica technique similar to that employed in electron fractog-

Jan 1, 1968

By W. R. Ingalls

THE main objective of everybody, individually and collectively as the people of nations, is to earn their living and improve the scale thereof as much and as rapidly as possible. We are able to earn" our living only by working and producing. We I are able to rise to higher standards of comfort only by increasing our production of goods, or diminishing the waste of those that we do produce, or both. This statement is trite. It is equally trite to dwell upon the importance of increased production to be derived from increased efficiency of labor and improved manage-ment; and the good results that would accrue to every-body if employers and employees would work together to secure the maximum of production at the minimum of cost. All of this is nothing more than platitude, to which every intelligent person subscribes in the abstract; but what concerns us especially, and what is neither so easy nor so understandable, is to translate the expres-sion of the abstract principle into formulas for action. The national net income obviously may be increased in two ways, or by both together. One is to diminish the waste of the goods that we already have made available. The other is to increase the supply of goods. .Increasing the supply of goods may involve the elimina-tion of waste, but a distinction is to be drawn between the waste of things that we have and the failure to obtain those that we might have. If we limit the term "waste" to the careless and profligate use of the materials that have come into our possession, together with the absorption of labor in doing obviously unnecessary things; and if we character-ize by the term "inefficiency" the failure to accomplish in our industrial operations the best of which we are capable, we shall create a distinction that will be pro-motive of clear thinking. In this paper I am going to deal with inefficiency, not waste, observing the distinc-tion, arbitrary if you please, that I have made. Without any doubt the greatest inefficiency that exists in our economic affairs is that which causes hundreds of thousands, perhaps millions, of men to be idle a good deal of the time. The major reasons for such idleness are two-fold. One of them is the conse-quence of what for convenience may be called business cycles, although I do not hold to the hypothesis of business cycles as it is now being rather widely expounded. That hypothesis involves the idea of rhyth-mic undulations due to causes unknown, but which it is hoped may be ascertained. The movement of busi-ness in waves up and down is undeniable, but that there are recurrences of cycles every so often is purely imag-inary, I think. It is unnecessary-to digress into that subject. The extents of the rises and falls above and below a median line undoubtedly is less than is commonly supposed.

Jan 3, 1922

By L. W. Blau

PERHAPS the most important event f or exploration geophysics in 1940 was the publication of three textbooks : "Geophysical Prospecting for Oil," by L. L. Nettleton ; "Exploration Geophysics," by John J. Jakosky; and "Geophysical Exploration," by C. A. Heiland. The literature had grown so bulky, and such a long time had elapsed since the publication of the texts by Ambronn and Eve, that treatises covering exploration geophysics comprehensively in all its branches and giving literature and patent references were sorely needed. This need has been satisfied admirably in these textbooks, and geophysicists owe the authors a debt of gratitude. In 1940, geophysics came of age. A conference on applied nuclear physics was held at Massachusetts Institute of Technology from Oct. 28 to Nov. 2. Several papers on geophysical subjects were presented at this meeting. Geophysical activity has decreased in all parts of the world except perhaps in Canada where, under the stimulus of the war's increased demands, prospecting for oil has increased. However, even there the war has had a seriously adverse effect on prospecting for ores and upon the promotion of new properties, although activity in producing and near-producing mines has been stimulated.

Jan 1, 1941

By Ferit Gurses

EXTENSIVE coal and lignite deposits exist in Turkey. Bituminous coal is the nation's principal mineral resource; important not only as fuel for the industrial development of the country, but also as a means of obtaining foreign exchange. Of the electrical power generated during 1939, 82.8 per cent was derived from coal.1 It is anticipated that the lignite deposits will be one of the major sources of power for the electrification of the country. BITUMINOUS COAL The locations of the four principal bituminous-coal2 basins are indicated on Fig. 1. The Eregli-Zonguldak basin lies on the Black Sea northwest of Ankara; the Canakkale basin lies near the junction of the Dardannelles; the Trakya basin is in European Turkey northwest of the Bosphorus and the Erzurum basin lies far to the east. The Eregli-Zonguldak basin is the most important of the four. This coal basin was discovered in 1829 but did not arouse interest until 1848; up to 1865, its annual production had not exceeded 50,000 metric tons. In 1865, during the Sultanate, working of coal mines was started by the Navy department, and the annual production was 61,145 metric tons. In 1908, the Minister of Commerce and Agriculture was authorized to develop the whole coal basin. Production reached 264,397 metric tons in 1910, and during 1915-1922, preceding the revolution, the total production of the basin was 2,676,043, or an average of 334,000 metric tons annually. The period of national revolution that followed was marked by a steady increase in coal production in Turkey, although world production decreased, because of the crisis of 1929-1932, about 52 per cent. AREA AND GEOLOGY OF THE COAL BASIN The geology of the Eregli-Zonguldak area is not yet completely known. The basin begins at Gungazi, to the west of Eregli, and extends to Sogutozu, a distance of about 106 miles. The coal beds, however, appear only in places and the overlying Cretaceous strata hide them elsewhere. This area includes the most important centers, such as Kandilli, Alacaagzi, Teflenli, Kozlu, Gelik (see Fig. 2). The geological sequence of the district is correlated with the Cretaceous of the Balkans; which is, in turn, a prolongation of the Alpine zone. Geological surveys made by G. Ralli, R. Zeiller and P. Arni3 show that the Eregli-Zonguldak formations fall into three natural divisions. Series a, The Alacaagzi in the district of that name (Fig. 2), is of the Culm stage. The strata strike generally east-west and dip about 30° south. This series appears also around Kandilli and Camli, with a steeper angle of dip, but the deposits there lack regularity. The Alacaagzi stage appears also farther east, to the south of Kozlu and Gelik. The Alacaagzi series contains 15 seams of an average thickness of 2 ½ ft. of good coal. Series b, the Kozlu, best represented in Zonguldak, Kilimli, Catalagzi, and between

Jan 1, 1944

By E. C. Truesdale, W. K. Waring

The Research,Division of The New Jersey Zinc Company (of Pa.) has conducted, over a period of years, numerous tests of the reducibility of various zinc ores and the reactivity of various kids of coal, using a number of different experimental methods. Most of these tests have involved the reduction of mixtures of ore and coal. In such cases the following simultaneous reactions are believed to be mainly responsible for the production of zinc, as was shown by Bodenstein' some years ago: ZnO + CO = Zn + CO2 [i] C + COj = 2CO [2] Each of these reactions is dependent upon the other for the supply of CO and COz, respectively, and the over-all rate of formation of zinc vapor will be determined by the slower of these two reactions. An analogous pair of reactions sometimes of importance is: ZnO + He = Zn + HZO 13] C + Hz0 = CO + He U3 While it is possible to obtain an indication of the relative reducibility of various ores, or of a fine versus a coarse Ore, by testing them with a given coal, and while coal reactivities may be measured in a corresponding manner, a more direct determination of relative reaction rates is possible by carrying out the desired reactions, such as I and 2, separately and under reproducible conditions. It is one purpose of this paper to present some of the results that have been obtained by the latter method. C. G. Maier2 discusses the relative rates of reactions I and 2 and concludes that while at relatively low temperatures reaction I is faster than reaction 2, this difference becomes less with increasing temperatures, although at smelting temperatures reaction is still the faster. He also says (p. 48), "At temperatures . . . be- -tween 1100' and 1300°C., . . . the zinc oxide reduction reaction is intrinsically more rapid than its physical limitations; that is, it is limited by gas diffusion rates.'' In the course of numerous reactivity tests involving the separate use of reactions and I and 2, we have obtained data that show by direct experiment, we believe for the first time, the correctness of Maier's statements concerning these reactions. We also include data on the relative rate of reaction 3, involving reduction by hydrogen. Finally, some interesting results obtained by carrying out the reduction of ' a zinc ore-coal briquet in streaming atmospheres of nitrogen, carbon monoxide and hydrogen, respectively, are presented.*

Jan 1, 1944

By S. E. Szasz, E. J. Moore, B. F. Whitney

An accurate value of formation water resistivity R, is essential in calculating formation porosity and fluid saturation from electrical well logs. In the cases where R, has not been measured directly, it must be obtained from other data, e.g., the SP curve. This paper deals with another approach: how to calculate R, from the chemical analysis of the formation water. INTRODUCTION It is known that the resistivity of aqueous solutions of pure salts depends on their concentration and on the temperature; the concentrations are given in MPL (mg of solute per liter of solution), or sometimes in ppm (mg of solute per kg of solution): MPL = ppm X specific gravity. Values for different pure salts are available in the literature, but not for solutions of mixtures which are of practical interest. The major component of the dissolved material in almost all formation waters being sodium chloride, it is customary to express the resistivity of formation waters in terms of equivalent sodium chloride concentration, i.e., the concentration of a solution of pure NaCl which has the same resistivity at a given temperature as that of the formation water under consideration. Thus, the problem of calculating R, from the chemical anaylsis can also be stated as how to convert the other constituents of the solute into equivalent NaCl concentration. Salts dissolved in water are at least partly dissociated into ions, and do not conserve their identity. If known amounts of several salts are dissolved in water, the solution does not necessarily contain the same salts in the original proportion, but perhaps some other combination of the ions, along with free ions in solution. This is why the chemical analysis of formation waters is often given in terms of ions, as if all dissolved salts were completely dissociated. Our problem then boils down to how to convert the concentrations of the various ions to equivalent concentrations of Na' and C1-. Dunlap and Hawthorne' have proposed to convert the concentration of all other ions to equivalent Na' and C1-concentrations by means of constant multipliers; e.g., 0.95 for Ca"; 2.0 for Mg"; 0.27 for HCO 3-; 0.5 for SO, -, etc. Their factors were based on measurements made at 68F on 26 formation water samples from the Texas Gulf Coast, ranging in concentration from 1,500 to 75,000 ppm. The Dunlap method is widely used in electric log interpretation, and is often extrapolated beyond its original concentration range. A comparison of R, values calculated by this method and values actually measured on formation water samples has shown large discrepancies, especially at higher concentrations. Therefore, two new methods were developed at Sinclair Oil Corp.'s Tulsa Research Center to calculate equivalent sodium chloride concentration from the chemical analysis of formation water samples. FUNDAMENTAL CONSIDERATIONS The resistivity of a solution, or its reciprocal the conductivity, at a given temperature is determined by the charge, concentration and mobility of the ions actually present. Monovalent ions such as Na' or C1- always carry the same charge. Compounds of polyvalent ions, however. may show incomplete dissociation, e.g., NaSO; + Na' instead of SO,-- + 2Na'. This happens especially in more concentrated solutions. Only very dilute solutions are completely dissociated, as assumed in the chemical analysis report. At higher concentration, the degree of dissociation depends not only on the nature and concentration of the particular salt under consideration but also on the nature and concentrations of the other solutes. Mobility of the ions depends on the viscosity of the solution. It also depends on the degree of hydration of the ions, which in turn is a function of the nature and the charge of the ions and also of the amount of free water available per ion, i.e., the total ionic concentration. The net effect is that the conductivity increases slower than proportional to the concentration, even if a solution contains only one salt such as NaC1, and is different for different salts (Fig. 1). Conductivity can even decline with a further increase in concentration, e.g., if additional salt is little dissociated but ties up some of the free water and/or causes an increase in viscosity. In solutions containing more than one salt, the contribution of one salt to the total conductivity depends not only on the fractional concentration of this same salt, but also on the concentration of all other solutes. A perfect method would give the conductivity or resistivity of a solution as a function of the concentrations of all solutes present. This is so complicated as to be impractical, and a simpler method must be found which is of acceptable accuracy. The Dunlap method, on the other hand. is too simple because it askmes that at any concentration the contrih-

Jan 1, 1967

By V. F. Marsters

SEEPAGES Of oil in Ecuador have been known for many years. The locality first to receive attention, and still worked in a modest way, lies on the north shore of the Santa Elena peninsula, between La Puntilla and Salinas. Operations were first conducted largely by local capital. Later, foreign companies acquired large blocks of land, where they have done considerable drilling. For details concerning present drilling activities in Ecuador, we are indebted to Leon Price, an American resident engineer of Ecuador. The information solicited, came to the author through the office of the American Consulate,' with permission to use it. The coastal plain bordering the Province of Tumbes, Peru, continues to the northeast, but narrows on passing the Zarumilla River. From this, point northward it widens toward Santa Rosa. In fact, the pampas, as shown on the official Wolf map, correspond fairly well to the areal extent of the coastal plain as far as Guayaquil. This is shown in a general way on the accompanying map. The author understands that the Guayaquil embayment is bordered on all sides by the coastal plain, as recognized at Tumbes and farther southwest, and that it can be followed without a break as far north as Palmar. This view is supported by the mapped area regarded by Mr. Price as favorable or possible oil territory. Moreover the islands in the Gulf of Guayaquil are the same geologically as the coastal edge, being composed of Tertiary sediments. The author understands also that Tertiary formations occur north of Palmar. According to a report by Mr. Cardon, of Guayaquil, Tertiary sediments are exposed in the region of San Francisco and extend to and beyond Pta. Calera. There is also reason to believe that at least the lower part of the valley of the Santiago River is occupied by Tertiary sediments, which probably border the coast line and extend into the River Mira basin, and into Colombia.

Jan 7, 1922

By J. Stubbins

1 1.4-1. Source of Water. Precipitation in the form of rain or snow is the original source of water that enters most surface mines. The precipitation, which does not escape to the atmosphere, either becomes surface run- off or infiltrates into the ground to become ground water (3,4). Evaporation and surface run-off can be measured. The water that infiltrates the ground disappears from view and is more difficult to evaluate. In general, it moves in a pattern similar to the surface run-off, but at a much slower rate, since its progress is impeded by many subsurface conditions. The infiltrating water descends through the soil and rock by whatever passageways permit flow until the water table or top of the zone of saturation is reached. Though usually pictured as a level surface, it is dependent upon the topography and the permeability of the enclosing material, and therefore it can be as erratic and unpredictable as the subsurface geology. Ground water may become surface run-off again at a lower point, and likewise, surface run-off of lakes and streams can infiltrate to become ground water. Should the ground water be confined to a permeable zone overlain by an impermeable barrier, a pressure is created. Such water is said to be artesian if the pressure head is sufficient to raise the confined water to the surface. These conditions are more commonly found in relatively flat-lying bedded formations. 11.4-2. Recognition and Estimation of Water. Dewatering and flood control should be considered by the design engineer at an early stage in all surface mine planning. Recognition of the possible problems, and making allowance for their solution, is an inexpensive precaution. Circumstances which should lead to investigation are: 1. High rainfall 2. Experience of other mines in the area 3. Evidence of water and caving in drill holes 4. Presence of springs and artesian wells 5. Geological evidence of aquifers.

Jan 1, 1968

By Frederic Dewey

IT IS common to blame irregular assay results upon volatilization and much has been written upon the subject, but there is no. real evidence that, in a properly conducted assay, the loss of either gold or silver by volatilization is sufficient to affect appreciably the result, even when, arsenic or antimony may be present. Bulk assays of flue dust from assay muffles have been published, but the data given are totally insufficient to even approximate the volatilization from a single assay; and such figures as we have indicate the volatilization to be extremely small. Diligent search in the literature and wide inquiry among assayers and instructors have failed to produce a single case where the litharge volatilized in making an assay has been collected and assayed for gold and silver. Having attempted to do this, with most indifferent success, I am not surprised that this has not been done. While various textbooks give volatilization as a cause of loss in cupellation, it may safely be said that in the rare cases where this volatilization is sufficient to affect appreciably the result it is due to excessive temperature. Percy1 says "The loss of silver by volatilization during cupellation is very slight (unless the temperature has been much too high), and may be disregarded." This statement is repeated by the Beringers2 and Smith,3 who includes gold with silver. Mitchell4 says the litharge fume rarely contains over one ten-thousandth of silver. Campredon5 says that at a proper temperature no silver is lost by volatilization.

Jan 2, 1920

By David R. Mitchell, R. M. Fleming

MANY trends were evident in the coal industry during 1951. Some were favorable for the industry; others were not. Probably those having the most far-reaching consequences are those affecting coal's markets. The rapid dieselization of many railroads and the continued trend toward oil and natural gas for home heating has caused serious dislocations in various mining districts. Mines have been forced to close down or to work on a reduced time basis. Conversely the increased activity in the metallurgical industries has increased the demand for coking and special purpose coals, and the growing production of electric energy has increased the demand in certain areas for steam coals. The increased demand for metallurgical coal and for steam raising by the large utilities is more than equal tonnage-wise to the loss of coal to railroad dieselization and conversions to oil and gas in the domestic market. Since much of the expansion is at captive mines of large corporations, many commercial operators supplying railroad and domestic users have had their markets curtailed without any compensating demand from other sources. Feverish activity was in evidence in many areas by commercial operators attempting to find new markets. The Norfolk and Western Railway is the, only major American railroad committed to the burning of coal. It has an exceptionally good cost record. During 1951, fifteen additional modern coal-burning steam switching locomotives were authorized for construction in the company's Roanoke shops at a cost of about $1,450,000. When the new order is completed the road will own a total of sixty locomotives of the modern-switcher type, including thirty acquired by purchase last year. The Norfolk and Western today is the only American railroad building its own motive power. All of these locomotives burn coal. Production Coal production in the year 1951 will approximate 570 million tons of anthracite, bituminous coal, and lignite. Of this, approximately 7 pet is anthracite. Total production is approximately 30 million tons more than in 1950 and reflects the increase in general industrial activity. Exports are expected to be close to 50 million tons. The industrial stockpile is close to 75 million tons, the highest it has been since 1943. With the exception of the usual local stoppages the year 1951 was unmarked by labor disputes. It was a year of good labor-management relations with a negotiated wage increase unmarred by a work stoppage. This may be the beginning. of an era of sensible negotiations to find agreeable settlements of disputes without the usual protracted bickering and industry-wide strike. The United Mine Workers of America has condemned wildcat strikes, stating that in nearly every, instance proper grievance procedures have not been instituted. Government defense organizations, perhaps profiting by their experiences during World War II, are pursuing a more enlightened program with regard to the fuel requirements of the nation. Many prominent officials have stated that wherever possible coal should be considered the primary source of fuel in all defense expansion. With the increased consumption of steel by defense projects, approval of transportation facilities for liquid and gaseous fuels have been refused where these fuels would enter a coal producing area. Liquid and gaseous fuel producers also have failed to provide satisfactory evidence that they have sufficient reserves and are capable of supplying their product in adequate amounts for the periods of time required. Realization has at last become prevalent that the hydro-electric power installations in several areas are insufficient to handle increased demands.' Steam generating plants are being constructed in these areas and equipped to burn coal. Most notable of these, is the TWA area whose supplemental steam power plants are expected to consume 10 million tons of coal per year when completed. The Pacific Northwest is another area which is expected to follow the same pattern. Nearly all new steam-power generating plants are being equipped to burn coal either as a primary fuel or as an emergency measure. Metallurgical Coal The steel and other metallurgical industries are expanding rapidly to meet increased industrial demands and defense orders. Since these industries are dependent on coke, coke has had a year of high production and can be expected to break all existing records when steel-plant expansions are completed. Most notable of the expansion projects is that of the Delaware River area where the iron ore will be received by ship from Canada and South America. U. S. Steel is only one of several steel corporations that are planning on putting integrated steel producing units in this area. The Defense Solids Fuels Administration announced in December that through. November 30, 1951. 29 projects in eight states, with a total cost of

Jan 1, 1952

By H. F. Gossenberger, J. J. Tietjen, J. J. Gannon, C. J. Nuese

External quantum efficiency measurements at 300" and 77°K are presented for vapor-grown GaAs and GaAs1-xPx electroluminescent diodes as a function of junction depth and doping. In GaAs, external efficiencies are found to decrease exponentially with increasing junction depth, defining an average absorption coefficient of 900 cm-1 at 300°K and 350 cm-1 at 77°Kfor epitaxial layers of p-type GaAs. It is shown that photon absorption losses dominate at room temperature and, in fact, account for most of the external efficiency degradation between 77° and 300°K. Healever, the internal ('junction) quantum efficiency is also found to decrease by a factor of 3.5 between 77" ALTHOUGH rapid progress has been made in recent years with GaAs, Gap, and their alloys for use in electroluminescent diodes, there are still important unknown factors related to the performance of these de- and 300°K. The dependence of GaAs efficiencies on donor and acceptor concentrations is presented, illustrating best efficiencies at donor concentrations of 1.5 to 2x 1018 cm-3 . External efficiencies are found to be independent of acceptor concentrations less than 3 x 1019 cm-3 but to degrade at higher doping. The fabrication of GaAsi-xPx electroluminescent diodes is briefly discussed. External efficiencies here for planar uncoated diodes are about 0.035 pct at 300°K and 0.4 pct at 77°for x = 0.42. A brightness of about 8500 ft-Lamberts is attained at 77°K and of 315 ft-Lamberts at 300° K. for curvent densities of 10 amp per sq cm. vices. For example, although the external efficiency is known to decrease by factors of typically 10 to 30 between 77°K and room temperature, the exact causes of this are still uncertain. Experimental results of ill' and carr2 with zinc-diffused electroluminescent diodes suggest that this external degradation is almost entirely due to increased absorption losses at room temperature, with a relatively temperature-independent internal efficiency; recent calculations by Gonda et al.3 corroborate this hypothesis. In contrast, Pilkuhn and Rupprecht4 find the internal efficiency of solution-grown GaAs laser diodes to degrade from 100 to 66 to 40 pct as the temperature is increased from

Jan 1, 1969

By Francis Donaldson

The direct injection of cement grout into water-bearing fissures as a means of checking or stopping the flow of water into shafts and tunnels has been experimented with for a decade or longer and seems to have been first attempted in Europe. The earliest application of which the writer has found a record was at a shaft sunk by the Mining Society of Lens; this is described by C. Dinoire in the Transactions of the Institution of Mining Engineers.1 It is only lately, however, that the process has been entirely successful. This success has been accomplished on the Catskill Aqueduct, now under construction by the city of New York. This aqueduct includes a number of deep pressure tunnels, reached by shafts for both waterway and construction purposes. In portions of these shafts and tunnels considerable underground water was met. The contract for the first of these deep pressure tunnels was let to the T. A. Gillespie Co.; this section is known as the Rondout Siphon. It leads under the Rondout valley at a depth of from 400 to 800 ft. and is about 5 miles long. The engineers expected that considerable water would be encountered, but fortunately this was not the case except at one shaft, known as No. 4, which penetrated the rock at a junction between limestone and conglomerate. Water-bearing fissures were encountered almost immediately. At a depth of about 200 ft. a flow of 1,500 gal. per minute was struck. The. shaft then contained as many pumps as could be used, and it seemed impossible to sink it further. After vain efforts had been made to proceed, John P. Hogan, a division engineer of the Board of Water Supply, suggested that cementation of the fissures be tried. The process was attempted for the first time in this country. Since the shaft was partly full of water it was necessary to drill grout holes with a diamond drill. Platforms were placed on the timbers at the water level, the diamond drill was installed and six 90-ft. holes were drilled in the bottom of the shaft. Several car loads of cement were pumped through these holes into the fissures, the drill casings being used for grout pipes. This largely cut off the flow of water from, the bottom and sinking could then

Jan 1, 1915

By Morris Cohen, Robert C. Ruhl

The phases in Fe-C alloys over a wide composition range have been studied after splal quenching from the liquid state. Binary alloys containing 0 to 5.1 wt pel C as /cell as a large number of ternary Fe-C-Si alloys with 2.5 to 5.0 wt pct C and 0.3 to 5.1 wt pct Si were attlong those sludied. Olher Fe-C-X alloys, zcilh X being Co, Cr, ,Wn, Ni, and Ru , were also inrestigated after splat quenching. At high carbon contents, a new hcp phase (designaled 6 phase, but different from e carbide) is retained upon splat quenching. The .fraction of this phase varies up lo 97 pcl for a Fe-4.K-1.9% alloy. The composition of the E phase ranges from about 3.8 10 4.8 wt pet C, and the corresponding laltice parameters increase linearly ulith carbon content, while the c/a ratio remains essentially conslc~nl. The E phrtse appears to he a solulion of carbon in E iron, the latler being nornially found only at high pressures. It is deduced that the unit cell of the E phase corresponds to the formula Fe12C3, and llzal il is relaled to tlie ordered slruclures 0.f 6 iron carbide and c iron nilride. The E phase is compared and contrasted to the olher known carbides and nitrides of iron and nickel. An exlrapolaTion of the atomic volume 1,s carhon conlent of /he E pllase lzcts giz.en a neu7 estitnale jor /he alomic volume of E iron, 11.30 cu A, a1 atmospheric pressure and temperature. Other alomic volume relalionships lead to /he co~zpositioti Fe2.iC tor E iron carbide, /he unit cell fortr~ula being -Fe2rClo The E phase undergoes a lulo-slage decomposition upon healing, .forrning firsl rnarlensile plus E carhide, a/ler 1 hr at 140" lo 200°C, slid then ferr ite Plus cementile, after 1 lir a1 330" to 460°C. A1 carbo,l contents between 1.5 and 3.0 LC/ pcl, (he predo.wirzar/t plzase alley quenching is fcc austenite. The retained carbon content of this phase increases with itlcreasing silicon in certain concentration ranges, reaching a maximum of 2.37 wt pct C itz a Fe-2.6C-4.OSi alloy. This is the highest carbon conten1 reLaitled in austenite to date. These high-carbon aus-tenites can be partially tm?zsforttled lo tnartensile hy severe deformation in the temperature range of — 190 to -50°C. TECHNIQUES for splat quenching from the liquid state have been utilized in numerous recent investigations to produce metastable phases in a variety of alloy systems. Among the several ways of splat quenching, the shock-tube method appears to yield the highest cooling rates1-3, 7, 8 and was adopted here. Estimated cooling rates attained in the present experiments ranged from 10' to 10 80Cper sec.' As a part of a research program on interstitial al- loy phases, the Fe-C system was selected for splat-quenching studies. It was hoped that splat quenching would allow high metastable supersaturations of carbon to be retained in solution. Also of considerable interest were the conditions governing the occurrence of the various intermediate phases upon solidification. The alloys investigated included both binary Fe-C compositions as well as six ternary Fe-C-X alloy systems. The known phases in the Fe-C system are summarized in Table I.* Only the ferrite and graphite are ent investigation.14 and is described in detail herein Table II summarizes corresponding data on Fe-N phases, which are also of interest here because of their similarity to the Fe-C phases. EXPERIMENTAL PROCEDURES Alloys were prepared by melting the elements. 99.9 pct purity, in an inert gas nonconsumable electrode arc furnace. The buttons. weighing about 5 g. were remelted twice. were then fragmented. and their interior surfaces were examined for uniformity: if any doubt existed. they were remelted again. Chemical analyses were performed on all the alloys. the accuracy being about k0.05 wt pct. At high temperatures, carbon-containing alloys react with alumina crucibles as follows: If the atmosphere in the splat-quenching furnace does not contain sufficient carbon monoxide the alloy can be depleted of carbon and contaminated with aluminum. Calculations and experimental observations showed that 50 to 100 torr CO partial pressure effectively blocked the above reaction in all the alloys investigated. The splat-quenching equipment in Figs. 1 and 2 provides for evacuation and back-filling with CO-Ar mixtures. The furnace is capable of operation up to 1650°C. and the gettering action of the graphite heating element reduces the oxygen partial pressure in the furnace atmosphere to below 10-5 torr, thus preventing oxidation of the specimens.

Jan 1, 1970

By Francis Donaldson

THE direct injection of cement grout into water-bearing fissures as a means of checking or stopping the flow of water into shafts and tunnels has been experimented with for a decade or longer and seems to have been first attempted in Europe. The earliest application of which the writer has found a record was at a shaft sunk by the Mining Society of Lens; this is described by C. Dinoire in the Transactions of the Institution of Mining Engineers.1. It is only lately, however, that the process has been entirely successful. This success has been accomplished on the Catskill Aqueduct, now under construction by the city of New York. This aqueduct includes a number of deep pressure tunnels, reached by shafts for both waterway and construction purposes. In portions of these shafts and tunnels considerable underground water was met. The contract for the first of these deep pressure tunnels was let to the T. A. Gillespie Co.; this section is known as the Rondout Siphon. It leads under the Rondout valley at a depth of from 400 to 800 ft. and is about 5 miles long. The engineers expected that considerable water would be encountered, but fortunately this was not the case except at one shaft, known as No. 4, which penetrated the rock at a junction between limestone and conglomerate. Water-bearing fissures were encountered almost immediately. At a depth of about 200 ft. a flow of 1,500 gal. per minute was struck. The shaft then contained as many pumps as could be used, and it seemed impossible to sink it further. After vain efforts had been made to proceed, John P. Hogan, a division engineer of the Board of Water Supply, suggested that cementation of the fissures be tried. The process was attempted for the first time in this country. Since the shaft was partly full of water it was necessary to drill grout holes with a diamond drill. Platforms were placed on the timbers at the water level, the diamond drill was installed and six 90-ft. holes were drilled in the bottom of the shaft. Several car loads of cement were pumped through these holes into the fissures, the drill casings being used for grout pipes. This largely cut off the flow of water from the bottom and sinking could then

Jan 1, 1914

By T. J. Woodside

A. E. LEE*—One question of the flue leading to the tube coolers. What gas velocity is maintained to prevent settling of the finely divided fume ? T. J. WOODSIDE (author's reply)— 30 fps. Of course some fume settles out, but is immediately carried away by the screw conveyors. H. R. BIANCO —How effective are the soot blowers ? Do you have to use any hand lancing? T. J. WOODSIDE Only one point, which is right at the top of the economizer and which the soot blowers do not reach, we occasionally hand lance. But everywhere else the soot blowers have been very effective and no hand lancing has been done. L. V. DAVIDSON*—Do you have considerable variation in the lead content of the fume collected if the lead is higher, and is there greater tendency for the fume to stick on the boiler tubes ? T. J. WOODSIDE—There is very little variation in the lead content. From 5 to 7 pct is the widest range variation we have had and we have noticed no difference in the behavior of the fume. C. R. KUZELL—Mr. Woodside has been quite generous with data pertaining to metal and fuel economics. I think he stated that the coal consumption of the furnace was 21/10 21/10 for a pound of zinc recovered. I take it that that is the gross coal input to the furnace. I wonder what the net fuel consumption in terms of coal might be after crediting the fuel equivalent of the waste heat steam recovered? T. J. WOODSIDE—The fuel value of the waste heat steam is approximately 42 pct of the heat input to the furnace. A very large part of the heat, of course, goes out in jacket water—44 pct. A. D. TERRELL*—I would like to know how much lead is in the deleaded material. T. J. WOODSIDE—It is a little less than 2 pct now.

Jan 1, 1950

OLIVIA'S recent revolution, by hindsight, seems to have been inevitable. The misery of the majority of the people, coupled with the economic crisis engendered by the refusal of the United States to meet Bolivian demands for a higher tin price, gave the National Revolutionary Movement party all the excuse it needed for overthrowing the government. Most of the mines in Bolivia are owned by three families. Precisely what it will mean to the United States is still a moot question. Argentina, with a mixture of Marxism, Fascism, and few twists created by the Perons, is in a position to grab off much of the tin we need. Because of the contingencies of geographical location, language and a natural simpatico, Argentina may be able to continue its efforts to oust the United States from its South American markets. Point Four aid was supposed to be given to Bolivia, but only for agriculture. Even this was entirely too slow. Mining, Bolivia's other major source of income was forgotten by the Washington planners. Primary aim of the new power will be to diminish its dependence on the world tin market. At a time when the free world is fighting a battle for control of metal, it stands a chance of losing an important source of supply. With the accent placed on agriculture and other industries, mining in Bolivia is certain to suffer. Argentina will be in a position to get the available supply of tin, make a strong ally in the world order of things, and add to its power play against the United States in South America. Ten labor groups have formed the Bolivian Central Workers Union. The first item on their list for immediate action is the nationalization of the mining and railroad industries. They also came out for agrarian revolution and diversification of industry. President Victor Paz Estenssoro has promised to appoint a committee for the investigation of nationalization of the mines. At least, this is indicative of a feeling for the need for caution.

Jan 1, 1952