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By Oswald J. Heinrich

The responsibility resting upon the owners and managers of mines where fire-damp is generated, renders it a matter of imperative duty that a frill and correct statement of any explosion that occurs should be given to the public. But such a statement must be based on the testimony of impartial eye-witnesses or trained experts. Then a sad experience may result in the adoption of effective preventive measures. In the absence of any official and professional body of mining experts in the State of Virginia, the writer desires to submit to his professional brethren of the American Institute of Mining Engineers an account of an explosion which recently took place in a colliery under his management, and earnestly desires a thorough and impartial discussion on the Fats submitted. Description and Plan of the Mine.—The "Grove" shaft is situated at the nearest point 825 feet from the last old workings upon the Midlothian property, south of the old Pump shaft works. (See Plate 111.) The shaft was sunk by the former company, some thirty years ago, to the depth of 622 feet. An incline over 230 feet long, starting in a northwest direction at a depth of 105 feet above the shaft bottom, had been driven to explore the coal on the dip. A return of very small dimensions had been driven round the shaft on the south side, entering the upcast chamber. With the information obtained from the former company that a seam of coal about four feet thick, at a depth of 490 feet, had been found, and with the information obtained by the present proprietor, R. T. Burrows, of Albion, N. Y., by means of two boreholes on the dip west of the old shaft, in both of which workable seams of coal at various depths had been ascertained, the clearing out and thorough retimbering of this shaft were commenced in March, 1873. Borehole No. 1, at a depth of 4773 feet from surface, revealed a seam of coal. This borehole was afterwards carried to a depth of 1140 feet to the granite, without finding any other seam of coal. Borehole No. 3, at a depth of 608 feet, revealed the first coal-seam, 14 1/2 feet thick; at 633 feet, the second, 12 feet thick; at 662 feet the third, 1 foot thick, and at 692 feet the fourth, 43 to 5 feet thick. The borehole was stopped at a depth of 715 1/2 feet.

By G. A. Vissac

In the presentation which follows, wash-ability curves, such as are commonly used in making studies preliminary to the cleaning of any coal or to the concentration of any mineral, have been reduced in each instance to a single straight line; thus all the most important characteristics of the coal or mineral are represented in a form more advantageous than that in which such data usually are shown. To obtain consistent results, float-and-sink data must be based on a single definite narrow size range, which may be designated "a coal unit." It will be shown that such units, each embodying a different size range, can be grouped to form what may be termed "a composite coal." A three-dimensional presentation will emerge, which will closely identify the coal, illustrate its characteristics in a new manner and explain many obscure facts. Float-and-sink Tests For the preliminary study of any cleaning or concentration problem, or in the control of any operation, float-and-sink tests must be made. The results of these tests are grouped in tabular form and then illustrated in various systems of curves; but if such a graphic representation is to have the utmost practical value, it must offer at least the following advantages: (I) It must be easier to read than the tabular results, and (2) it must be easy to plot, check and interpolate. The first requirement will be attained by reducing the number of curves to a minimum, and the second by some system of representation that will use only straight lines. Of the many washing curves now in use, only the "recovery curve," often known as the "composite curve"—a somewhat misleading term—will be considered; Any point on the recovery curve will show what percentage of weight of clean coal can be recovered when the mineral is washed at a certain specific gravity. As an example, the tests listed below Fig. I are illustrated in the drawing by a curve obtained by plotting (I) as abscissas the ash content of the coal recovered and (2) as ordinates the corresponding percentage of refuse discarded; but, in general practice, instead of writing down that weight, it is customary to set down its complement, which is the corresponding weight of coal recovered. From this curve can be deduced the information necessary for the solution of most practical problems. New Form of Graphic Presentation The resemblance of the recovery curve ill Fig. 1, or, for that matter, the recovery curve obtained in common practice! to a Power curve is apparent. The general equation of such a curve is Y = axn, where n is negative. Taking logarithms: log y = a + n log x. Using a logarithmic scale, the equation of the recovery curve will be Y = A + bX. On this logarithmic basis! the recovery graph will be a straight line, using the same variables as in Fig. I; namely, the ash con-

Jan 1, 1942

By C. E. McCarthy, A. George Stern, Stanley J. Green

THE national interest prompts consideration of any new source of mineral wealth even though the immediate need may be of minor importance. A critical shortage of potash in the United States during the World War of I9I4-I8 stimulated broad development, which established an American potash industry on a basis so sound that this commodity is not even listed as urgent in the present war program. However, this should not minimize its importance, and the need remains, not only for adequate supplies of the usual potash salts (the chloride and the sulphate) but of all potash chemicals. Potassium carbonate (known commercially as pearl ash) has been a high-cost commodity; in consequence, the quantity used by industry has been relatively small. By a combination of fortuitous geographical circumstances, there is opportunity to produce a low-cost potassium carbonate with the possibility that this might become an important source of chemical potash. The following paper considers a recently developed process1 taking advantage of these conditions. WYOMINGITE DEPOSIT For many years it has been known that a deposit of potash-bearing igneous rock known as wyomingite occurs in the southwestern part of Wyoming at Zirkel Mesa, which is 44 miles northeast of the town of Green River (Fig. I). The western escarpment of this deposit is about 3 miles east of the Superior Branch of the Union Pacific Railroad. This mesa alone covers approximately 3300 acres, and the average thickness of the wyomingite flow is 75 ft. It has been estimated2 that about one billion tons of wyomingite occur in this one deposit, all of which can be mined by open quarrying without overburden. In addition, there are several smaller deposits within 10 miles, so that the aggregate wyomingite in the area approaches two billion tons. This is one of the world's largest sources of leucite, and the only known deposit of its kind in the United States. The wyomingite (which is in the form of a lava flow and numerous small craters), with the mineral leucite as its most important component, has a mineral composition3 of: leucite, 50 per cent; phlogopite, 15; diopside, I2; kataphorite, 15; glass and apatite, 8. The phlogopite is present in visible phenocrysts 1/8 to 1/2 in. in diameter, but the leucite usually is almost microcrystalline and not capable of liberation by grinding. Chemically, the wyomingite has a potash content averaging slightly higher than eleven per cent K20. The potash is mainly in the leucite, but part of it is in the phlogopite and a small amount is in the feldspars that are occasionally seen as undigested occlusions of the granite country rock, through which the leucite-bearing lava intruded, and as sanidine feldspar both in the crystalline and glassy phases of the rock. A typical analysis of the wyomingite from Zirkel Mesa is as follows:

Jan 1, 1944

By N. Tiner

In an article on magnesium and its alloys, Gann and Winston! stated that manganese has a limited solubility in the liquid state. W. Schmidt2 showed a diagram according to Joseph Ruhrmann indicating that the solubility of manganese in liquid magnesium falls from about 2.65 per cent at 790°C. to about 0.5 per cent at 675°C. The curve was extrapolated to show zero solubility at the melting point of pure magnesium (Fig. I). This work suggested that at the lowest manganese contents it was not possible to detect either a eutectic or the formation of a solid solution, so that manganese was stated to be present in the structure as large individual crystals. Two years after the presentation of, these results, Gann3 brought evidence to show that some manganese is capable of dissolving to form a solid solution, any excess of manganese present then assuming chiefly the form of small blue-gray particles scattered throughout the primary magnesium crystals, occasionally in clusters but seldom at the boundaries. He presented micrographs of cast alloys containing 0.1, 0.4 and 1.0 per cent manganese that show a small amount of coring around the individual particles due to solid solution, and indicate that the location of the manganese particles is closely associated with the original dendritic structure of the primary crystallization. He also pointed out that the amount of manganese that can be dissolved in magnesium depends on the amount of other alloying elements present, the effect of the second alloying element being to decrease the amount of manganese retained in the alloy. E. Schmid and G. Siebe14 have determined the solid solubility of manganese and its variation with temperature by means of precision X-ray diffraction measurements. They found that the solubility is 3.4 per cent at 645°C. and decreases to practically zero at 200°C. It is apparent that the X-ray diffraction measurements of Schmid and Siebel are not in agreement with the results of Ruhrmann as presented by Schmidt. This disagreement, and also the lack of data on magnesium-aluminum-manganese and magnesium-zinc-manganese systems, led the author to the present investigation, to determine accurately the liquid solubility of manganese and its variation with temperature. Experimental Method The experimental method for making solubility determinations consists of saturating the molten magnesium or the alloys with manganese at various temperatures and analyzing the dip samples taken from these melts. Melting is carried out in a cylindrical steel pot heated by an electric resistance furnace. The pot had a metallic outside coating to protect the steel against oxidation, and a graphite inside lining to prevent the contamination of the melt by prolonged contact with iron. The inside diameter of the pot was 4 in. and the depth 12 inches.

Jan 1, 1945

By J. H. Jackson, P. D. Frost, C. H. Lorig, A. C. Loonam

THIS paper describes (1) the effect of sodium on the tensile ductility of magnesium-lithium base alloys, and (2) the precautions necessary to avoid sodium contamination. Effect of Sodium on Properties The harmful effect of sodium in magnesium-lithium base alloys has been recognized by other investigators.1,2 However, quantitative data on its effect have not hitherto been published. The effect of sodium on the ductility of an 87 pct Mg-9 pct Li-4 pct Zn alloy is shown in fig. 1. The sodium was introduced by adding sodium chloride to the flux, which consisted of 50 pct LiC1-50 pct KC1. Moderately high ductility was obtained at an indicated sodium content of about 0.05 pct. Actually, the value probably was less than 0.05 pct, be-cause analyses of the lithium, which were more accurate than those of the alloy, indicated that the highest ductility was obtained when its sodium content was 0.02 pct or less. In fact, in alloys having somewhat greater strength than this particular composition, the sodium content of the lithium must be under 0.01 pct to avoid embrittlement. The effect of sodium on the ductility of several alloys having fairly low strength levels is shown in fig. 2. These alloys were melted with a flux containing 75 pct LiC1-25 pct LiF, to which various quantities of sodium chloride had been added. Sodium had no significant effect in pure magnesium but markedly decreased the ductility of the magnesium-lithium-zinc alloy, even though the alloy contained only 3 pct Li. As the lithium content of the binary alloys was increased, the ductility of the sodium-free alloys also increased. However, the effect of sodium on ductility became progressively more pronounced. Sodium raised the minimum hot-rolling temperatures, particularly those of the high-strength alloys, but its effect, in this respect, was less critical than its effect on tensile ductility. For optimum cold roll-ability, a low-sodium content was required. No deleterious effect of sodium on the stability of properties at slightly elevated temperatures was found. Control of Sodium in the Alloys Optimum ductility is obtained in the magnesium-lithium base alloys when sodium-free materials are used. Commercial lithium was formerly the chief source of contamination. Now purified lithium is usually available. When lithium of ordinary purity is used, the effects of sodium can be minimized by using a flux consisting of 75 pct LiC1-25 pct LiF. Bubbling nitrogen through the melt also helps remove sodium. The damaging influence of sodium on the ductility of the magnesium-lithium base alloys was observed very early in the alloy development program. The discovery came about as a result of chemical analyses made on the lithium used in the alloys. Ductile alloys had been made from lithium containing about 0.2 pct Na, whereas the lithium used in the brittle alloys contained about 0.9 pct Na. The first magnesium-lithium alloys were melted under commercial fluxes ordinarily used in melting magnesium alloys. These fluxes were unsuited for scavenging the contaminating sodium, and the resulting alloys were not ductile. Next, a flux containing 50 pct KC1-50 pct LiCl was tried. This was somewhat more effective but still was not satisfactory. After a number of different experimental fluxes had been investigated, one containing 75 pct LiC1-25 pct LiF was adopted. This flux made it possible to obtain good ductility in the alloys. The

Jan 1, 1951

By A. Lee Barrett

MINE power systems are quite different in many respects from those usually found in industrial plants. Wide areas are served, usually by a circuit which is connected continuously throughout the mine. In some mines one circuit may run for several miles. There are usually a small number of branch circuits involved considering the areas covered. In all mines circuits are sectionalized at approximately 2500 ft by means of switches. All, or at least most branch circuits, are sectionalized by manual switches. In some mines automatic sectionalizing gear is used to give automatic overload protection at various strategic points in the system. However at the present time this practice is by no means general. Circuit hazards in mine electric systems are much greater than those encountered in industrial installation. Falls of roof or coal form a prominent hazard which may break the wire and may cause ground faults or partial ground faults. Ordinarily electric cables in mines cannot be insulated, there- fore n fall can easily cause a short circuit. The humidity in most mines is greater than 95 pct and at many points the floor is wet and water may be dripping from the roof over insulators, increasing the difficulties at that point. All electrical circuits must be contained in the mine entries and space must also be provided for moving equipment and men. Consequently, because of the proximity of the power circuit to the locomotives and other moving equipment a considerable hazard is introduced. Mine haulage track is not always good so that wrecks are not unusual. A wreck frequently does consider- able damage to the power circuit. A ground fault frequently results in heavy arcing which may be sustained. If the damage to the circuit is mechanical it may mean that a trip of coal has wrecked and a great deal of coal dust could be thrown into the air as a result of the wreck. The arc resulting from the ground fault could ignite the coal dust and a mine explosion would result. A continued ground fault, even if high in resistance, also may ignite the coal which may be on the bottom of the entry and a mine fire may result. The fire hazard is one of the most serious hazards in any coal mine. Since the mine circuit is completely interconnected, any power interruption resulting from a fault seriously affects the whole operation. Unless the mine is completely sectionalized the whole mine will be shut down until the fault is located and the proper switches are opened to isolate the fault; even then large areas may still be without power if they are supplied by a single power circuit which may be opened in isolating the fault. Further, mine power is usually supplied from a relatively small number of substations and the fault may be on a stub feed circuit, in which case power cannot be restored until the fault has been cleared. Practice varies widely with respect to placement of substations. Usually they will be spaced from I to 2 miles in 500V operations, and at 1 mile intervals or less, in 250 V operation. Actual mining operations govern substation placements and no general rules can be followed.

Jan 1, 1948

By C. E. Lesher

COAL has been fighting a rear-guard action since the last World War. The battle against competitive fuels has been largely guerilla warfare with more sniping within the ranks than of organized opposition. Oil and natural gas are the fuels that over these twenty odd years have driven coal backward and out of many profitable markets. Now, somewhat timidly, the coal industry is trying a new weapon; namely, Research, or let us more properly say, Organized Research. Engineers have been designing this weapon for many years, supported by those interested in coal, including some coal producers. A part of this pioneer work has been Fundamental Research, the Ph.D. kind that is over the heads .of most of us. Another part has been aimed at immediate objectives and realizable profits, the practical, man-in-the-street sort. That is Industrial Research. Enough has been accomplished to make a fair exhibit, but whether this new weapon will have sufficient fire power to rout the opposition, whether the industry will really go into production and use it, the next few years will tell. NEED FOR COAL RESEARCH To utter "Research" is to use the modern magic word; to conjure up the miraculous-rubber from weeds; radar; magnesium from sea water; yes, even gasoline from coal. Research is a very general term. It means something different to every man. What is the coal industry seeking with its research; or what should it seek? And, specifically, how is it going about the job; and is it taking the best way? There are many who say that Coal has been asleep at the switch, while Oil and Gas have been taking the energy business. In an organized way this is true. Large-scale, privately financed research is just started in the Pennsylvania, anthracite industry, and it is still a dream for bituminous coal. What has been done so far collectively is purely defensive; as, for instance, to improve mechanical devices for burning coal so as to be able to recover markets for house-heating fuel long since abandoned to oil and gas. To appreciate just how seriously bituminous coal has slipped back in the national economy in the past 25 years, one has only to recall that, in the last war the Navy required for its operations all the high-grade, low-volatile coal that could be produced, and that anthracite was withdrawn from the middle and northwest markets to keep the eastern seaboard warm. All coal was "rationed" by zones, if not to individuals. Now the Navy, the Armed forces and the Merchant Marine are propelled by oil and gasoline. Gasoline and heating oil are rationed to individuals. Production of all coal in this country in 1918 reached the historic figure of 678,200, 000 tons, and in 1943, after 25 years, it is expected to reach a special wartime total of 660,000,000 tons. Meanwhile, production of crude oil this year may exceed 1,500,000,000 bbl., and like that of natural gas, reach four times the amount produced in 1918.

Jan 1, 1944

By F. V. Lenel, G. S. Ansell, M. J. Salkind

An experiment is described in which the growth of interparticle necks in an array of loose spherical silver powder at temperatures near 300°C was determined by measuring changes in the electrical resistance of the array. The activation energy for neck growth of contacts was derived by abruptly changing temperature and noting the change in the rate of neck growth. Since the experiments were run under an external load, the changes in activation energy with stress could he determined. The activation energy was found to decrease rapidly with increasing stress. It is concluded that the material transport in the experiments is one of plastic flow by dislocation motion. The variation of activation energy with stress is typical for cross slip of dislocations, an important material transport mechanism in the temperature range investigated. THE process in which powder compacts or aggregates of loose powder are held at an elevated temperature under an external load is called hot pressing or sintering under pressure by powder metallurgists. In this investigation the early stages of this process as applied to loose spherical silver- powder aggregates were studied. The powder particles were approximately 100µ in diameter and the temperature was near 300°C, i.e., below one half of the melting point of silver in degrees Kelvin, where volume diffusion is not expected to contribute to sintering. In the process, the contact or neck areas between powder particles grow. Since this involves plastic deformation of the particles under a constant external load (even though not under constant stress) it would be termed creep by mechanical metallurgists. On the other hand, the growth in neck area observed in compacts or loose-powder aggregates held at elevated temperature without the application of an external load is termed sintering by powder metallurgists. During sintering the major driving force is the stress due to surface tension. However, even when no load is placed on the compact or powder aggregate, an external stress, i.e., gravity, plays an important role in sintering in addition to those stresses arising from surface tension, as was shown in two previous investigations.'" It is therefore postulated that no sharp dividing line can be drawn between the phenomena of "creep" and "sintering". Different material transport mechanisms may be involved in either of these phenomena, but they will depend upon the temperature and the level of stress, but not necessarily upon the nature of the driving force: surface tension or external load. At the low temperatures of this investigation, an external stress much higher than the stress due to surface tension is necessary to obtain measurable rates of neck growth. In order to avoid misunderstanding this phenomenon will be called "creep". The rate of growth in contact area in the loose silver-powder aggregates was determined by meas-

Jan 1, 1965

Apparatus and a method for determining the volumetric behavior of hydrocarbons at pressures up to 10,000 psia and at temperatures between 0° and 460°F are described. The equipment is suitable for measuring the total volume of the system and the volume of a liquid phase as functions of state within these ranges of temperature and pressure. Introduction During the past two decades there has been a marked increase in the ranges of temperature and pressure encountered in underground hydrocarbon reservoirs of commercial interest. In addition, greater interest in the intensive characteristics of the fluids found in these reservoirs has developed. Apparatus Several types of apparatus have been developed in the authors' laboratory for volumetric measurements of hydrocarbon systems. The earliest equipment described1 was characterized by constant volume, and the weight of material present was varied systematically in order to attain the different pressures desired in the study. Later another apparatus2 was built in which the effective volume of the cylindrical cell, which confined a hydrocarbon sample of constant weight was varied by injection or withdrawal of mercury. The effective total volume of the equilibrium cell was measured by ascertaining the position of the mercury surface but no measurement could be made which gave knowledge of the volumes of individual phases existing within the hydrocarbon system. A third apparatus3 was designed for use at higher pressures and temperatures than the earlier equipment would tolerate. This apparatus was of the variable volume type but was built in the general form of a U-tube, the mercury level being measured at the surface which was not exposed to the hydrocarbon system. This arrangement avoided the need of subjecting measuring equipment to the extremes of temperature at which studies were made, but it gave no provision for measurement of the volumes of individual phases. Although this last apparatus was satisfactory as to accuracy and convenience for many purposes, need was felt for measurements of the volume of the liquid phase of the hydrocarbon system. For this reason a fourth equilibrium apparatus was designed and constructed, and it is the purpose of the present paper to describe it. The equilibrium cell has a working range of temperature from 0° to 460°F at pressures up to 10,000 psi. Provision for measurement of both total volume and liquid-phase volume makes it particularly suitable for the equilibrium study of heterogeneous systems consisting either of simple mixtures or of complex field samples of hydrocarbons. The general arrangement of the ap-

Jan 1, 1948

By Jack A. Kanz, Samuel R. Shortes, E. C. Wurst

Zinc diffusion into GaAs from the vapor phase through reactively sputtered SiO, films Izas been inrestigated for various zinc pressures at 1000"C. Diffusions were carried out in evacuated quartz ampules with elemental zinc and with various Zn-Ga alloys. Sputtered films have proved effective in lowering surface concentrations and preventing surface deterioration during diffusion. Approxin.ate complenzentary error-function impurity distributions were found when surface concentrations were reduced to approximately 3 -—4 x 10" atoms cm'3 or less with dilute zinc sources or by diffusion through SiO, films. Zinc difhsions in GaAs tlzrough SiO, films produced more planar diffusion fronts than were observed with uncoated zuafers under identical conditions. A) Surface Deterioration During Diffusion. Device technolorn-- in compound semiconductors has been hampered by several difficult problems not normally encountered with silicon and germanium. 111-V and 11-VI compound semiconductors generally have volatile constituents at temperatures used for diffusion. To achieve specific junction depths in reasonable lengths of time, or to obtain particular impurity distributions and doping levels, it is often necessary to use temperatures which cause surface deterioration and erosion of the wafer. The resultant surfaces are generally unsuitable for devices. The type and extent of surface damage depends to varying degrees on the particular environment of diffusion and on the particular impurity in question. The most common type of deterioration results from simple dissociation of the gallium and the arsenic during diffusin.' The deterioration process is significantly enhanced by thermal gradients in the diffusion zone, usually resulting in vapor transport and condensation at the cooler portion of the system. The resulting damage sometimes appears as a general haziness over the surface or an array of pyramidal etch pits characteristic of the particular orientation. Occasionally, erosion of the surface occurs uniformly over the wafer so that surface loss is not readily apparent. Workers in GaAs usually resort to the sealed-ampule type of diffusion system3"5 rather than the more conventional open system used for silicon and germanium. Another type of deterioration results from direct interaction of the impurity with the surface. The form of deterioration may vary from surface alloying, as in the case of zinc, to direct chemical attack and vapor transport of the reaction products, as in the case of sulfur. Surface alloying with zinc occurs at higher temperatures and source vapor pressures.4 The process is largely controlled by the amount of free gallium on the surface of the wafer in equilibrium with the arsenic lost to the system. The group-VI elements, sulfur, selenium, and tellurium, are commonly used donor impurities for gallium arsenide. These elements are characterized by high vapor pressures and high chemical

Jan 1, 1964

By J. M. Callow

The selective action of oils for lustrous minerals was first disclosed by Haynes in 1860. In 1885, Miss Carrie Everson elaborated this idea and also disclosed the fact that acid increased the so-called selective action. Her patent called for oils, either animal, vegetal or mineral, also for an acid or salt. The process was tried out on a practical scale in Baker City and Leadville, in 1889, and failed: first, because, as has since been shown, of the unsuitability of the ore to flotation; and second, because the invention was too far in advance of the times. Then followed the Elmore brothers, first with their bulk oil processes and later with their vacuum method. The basic principles of oil flotation were undoubtedly covered by the above inventors, the work done since their time being merely a building up on ground work laid by them. Different kinds of oil, different quantities of oil, and all the varying degrees of agitation, were all exemplified and practiced by them in one phase or another, and the developments that have since been made are but elaborations of the fundamental principles laid down by Haynes, Everson, and the Elmore brothers. In 1902, the Potter-Delprat process was developed in Australia. In this process no oil was used, the mineral being raised by the generation of gas, brought about by the introduction of acid into the pulp. The mineral particles appeared on the surface of the separatory vessel, in the form of a scum or froth, buoyed up by minute gas bubbles attached to them. This no doubt first gave the suggestion of gaseous flotation. In 1902, also, Froment, an Italian, was granted a patent in which he combined violent agitation with oil and gaseous flotation, the gas being generated within the pulp, in much the same way as in the Potter-Delprat process. In the same year, Cattermole came out with a unique method. First, the pulp was emulsified with a small quantity of oil, by violent

Jan 1, 1916

By L. A. Rapoport

This paper is intended as an aid in the perfornzance and interpretation of experimental studies of multi-phase flow in porous tnedia. The mathenmatical formulation of incompressible, two-phase flow phenomena in a three-dimensional porous medium is presented. The resulting equations which account for the effects of gravitational and capillary forces are used to derive general scaling laws permitting accurate representation of water-oil displacement processes by means of experimental flow models. The significance of the scaling laws is examined in the light of the physical concepts of micro-behavior of fluids in porous media. Formulations of scaling con(litions obtained by application of dimensional analysis are reviewed. The principles of application and the limitations of flow model studies are discussed. INTRODUCTION Most of the problems facing a reservoir engineer involve three-dimensional, two-phase flow systems. influenced by the effects of gravitational and capillary forces. Present computational procedures generally do not permit the evaluation of such systems without introducing greatly simplifying assumptions. The actual reservoir configuration is usually replaced by one or a combination of several "equivalent" linear systems, and the effects of capillarity and gravity are considered to be negligible. While these assumptions may in many instances be justified, there are a number of important practical problems for which the results obtained on the basis of such simplifications remain open to question. An alternate approach to the problems that are not amenable to analytical treatment consists of seeking their solution by experimental laboratory investigations. The main difficulty of such investigations lies in the fact that multiphase flow phenomena subjected to gravity and capillary forces proceed differently at different rates and in systems of different dimensions. Therefore, unless great discrimination is exercised in selecting the conditions and interpreting the results of laboratory tests, such tests may be entirely misleading in regard to field applications. The purpose of this paper is to present a theoretical background for the performance of laboratory tests that are more nearly representative of field behavior. It will be shown that simulation of field behavior can be achieved by conducting laboratory tests under conditions selected in accordance with definite scaling laws. The formulation of conditions required for the scaling of two-phase flow experiments in porous media has been presented in the literature on several occasions.12,3,4 One of these formulations advanced by Leverett1, cannot be considered applicable to most practical cases inasmuch as it does not cover generally the regime of laminar flow. An adequate treatment, based on the consideration of dimensional analysis, was presented by Engelberts and Klinkenberg.2 Their treatment, however, is concerned primarily with the scaling of linear flow systems, and hence somewhat limited in scope. Accordingly, the formulation of more general scaling laws, applicable to three-dimensional systems, appeared to be warranted. It appeared, furthermore. desirable to establish this formulation on the basis of a mathematical treatment, rather than by application of general principles of dimensional analysis, to permit more explicit

Jan 1, 1956

By G. A. Crowe, W. T. Bishop

WHILE the literature in the United States on general polarographic technique is extensive, very little appears to be directly applicable to the analysis of flotation tailings. For this reason, it seemed worth while to present a few polarographic methods of ore analysis that have been in constant use in the laboratories of the Hercules Experiment Station for the past few years. At the time of our initial investigation of the polarographic method, there was little or no mention of its specific application to flotation tailings. It was therefore necessary for us to establish suitable conditions for the analysis of our flotation tailings and to consider possible interfering constituents. The polarograph, or dropping mercury electrode, method was discovered in 1925 by J. Heyrovsky and M. Shikata,1 of the Charles University, Prague. This method has since received extensive development and the literature contains many articles on the use of the polarograph for the quantitative determination of metals as well as anions, oxygen in solution, and reducible organic compounds. Kolthoff and Lingane,2 by the publication of their book, "Polarography," in 1941 did much to advance the knowledge and use of the polarograph. In chapter 25 of that book, methods for the polarographic analysis of brass, steel and iron products, alloys, and zinc ore are given. Aluminum,3 cadmium,3.4 cobalt,4 copper,3-9 gold,10 iron,3,11 lead, 3,12,13 molybdenum," nickel,4.8,9 tin,15 and zinc3,4,5,7 in ores have been analyzed by the polarograph. However, most of the work on tailing samples has been published in Russian journals and translations are not yet readily available. In this paper we will describe the method that was developed and used in our laboratory for the determination of copper, zinc, and lead in flotation tailings. PRINCIPLE OF THE METHOD The polarograph is an instrument for applying a potential to a mercury pool and a dropping mercury electrode separated by a solution, and for measuring the resultant electrical current. The procedure is essentially a small-scale electrolysis, in which the voltage required to reduce or oxidize the material identifies it qualitatively and the current measures the concentration quantitatively. Different constituents in a sample may often be determined simultaneously provided they reduce at sufficiently different voltages. An example is the determination of copper and zinc in the same solution. The reduction potentials are quite far apart, as shown in Fig. I. The polarographic method is particularly useful in the range of concentration between those normally determined by spectographic and chemical methods. In

Jan 1, 1946

By W. A. Dunkley, W. W. Odell

The sulfur content of coal is perhaps more important in the manufacture of illuminating gas than in any other coal-using industry. Whether the gas is made by the distillation of coal in retorts or ovens or by steaming incandescent coal or coke in the water-gas process, a portion of the sulfur present in the fuel always passes into the crude gas. Practically all the sulfur that remains in the finished gas is transformed into sulfur dioxide (SO2) when the gas is burned. Sulfur dioxide is a pungent suffocating gas and, if present in the air in any perceptible amount, is deleterious to health and comfort and damaging to house furnishings. SO universally is this recognized that laws regulating the amount of sulfur that may be permitted to remain in the gas are very generally in force. The capacity of a plant to purify gas frequently limits the selection of coal for gas making. This condition may arise from different causes. Some plants were originally designed to handle a certain grade of low-sulfur gas coal, and very little leeway was allowed for growth or for the use of inferior coals. Other plants, when built, had ample capacity to purify gas from relatively higher sulfur coals, but their output has grown so rapidly that their purifying capacity is now limited and only the low-sulfur coals can be handled. There is a great quantity of coal in the United States that would satisfy the requirements of the gas manufacturer, were it not for the high sulfur content. The coals containing less than 1 per cent. sulfur are becoming scarcer year by year and, in time, the gas industry will probably be compelled to use coals that are now considered out of the question. Sulfur Compounds in CRude Gas Sulfur exists in unpurified illuminating gas in a variety of compounds; chief of these are hydrogen sulfide (H2S) and carbon disulfide (CS2). In crude coal gas H2S is usually present to the extent of 0.5 to 2.0 per cent., by volume, equivalent to about 300 to 1200 gr. per 100 cu. ft. of gas. In carbureted water gas, the amount of sulfur compounds depends not only on the sulfur content of the coal or coke used, but also upon cite

Jan 1, 1920

By Y. L. Yao

THE NaT1-type compound may be considered as the penetration of two diamond lattices in such a way that a superstructure of the bcc lattice is formed. Examples of the NaT1-type compound of lithium are LiZn, LiCd, LiA1, LiIn, and LiGa. Except for LiZn and LiCd, each molecule of these equiatomic compounds contains a total of four valence electrons. In LiZn and LiCd it was suspected (for example, see Ref. 1) that the fourth electron was withdrawn from the 18-shell of zinc or cadmium. An incomplete 18-shell would have to show strong paramagnetism. In 1955 Klemm and Fricke2 determined the magnetic susceptibility of LiZn, LiCd, LiA1, and LiIn (also NaTl and NaIn). The molar susceptibility of the outer electrons of LiZn and LiCd was found to be not strongly but weakly positive; that of LiAl and LiIn not negative but weakly positive. Thus they questioned the hypothesis about LiZn and LiCd in particular and the description of the NaT1-type structure in general. However, they did not determine the magnetic susceptibility of LiGa. This note is to report results for all five compounds of lithium. The starting materials are 99.9 pct pure lithium sticks containing less than 0.005 pct Na. 99.9 pct Zn, 99.9 pct Cd, 99.99 pct Al, 99.999 pct In, and 99.999 pct Ga. Weighed amounts of two components were wrapped in tantalum foil and placed in a graphite crucible. It was found that the tantalum sheath minimized the vaporization losses of lithium during melting. The sheath was easily stripped from the alloy rod and the tantalum in the alloy was barely detectable (less than 0.01 wt pct). The melting was performed in a resistance furnace under an argon atmosphere. Alloy specimens were annealed for 1 hr at 400°C in vacuum. The magnetic susceptibility at room temperature was determined by the Faraday Method, using the procedures previously described.' The results are shown in Table I. The interpolated values at 50 at. pct of Li and the average values at 48 to 52 at. pct of Li at 20°C determined by Klemm and Fricke2 are also shown. It is seen that the present value for LiZn and LiCd is slightly more positive but the present value for LiAl and LiIn is slightly less positive than their corresponding values. Also, it is noted there is an abrupt decrease of susceptibility of LiAl from 51.2 to 52.5 at. pct of Li. Klemm and Fricke2 found that the total susceptibility of LiZn, LiCd, LiA1, and LiIn is almost independent of temperature. slater4 gave a working expression for the diamagnetism of the atomic core as follows:

Jan 1, 1964

By C. S. Matthews, H. C. Lefkovits

The performance of depletion-type reservoirs at the stage in which the gas is at such low pressure that gravity is essentially the sole driving force has been investigated both theoretically and by use of scaled models. A simple theory is developed which completely explains the scaled model experiments. It also agrees with some field data. When the range of production rates to be considered is less than 25, the theory predicts that the production rate decline curve for homogeneous reservoirs in which there is a free surface will be of the hyperbolic type with n = 2: The theory gives a physical significance to the parameter y. INTRODUCTION This investigation was undertaken to determine a method for prediction of performance of reservoirs where gravity is the sole driving agent. Depletion-type reservoirs fall into this category after the pressure has fallen to some low value. Some examples of this type are found at Healdton ('Oklahoma), Oklahoma City (Oklahoma), Midway-Sunset (California), and East Coalinga (California). Generally the production rate per unit thickness is quite low in such reservoirs, with the conse- quence that this stage is sometimes called the stripper stage. However, per well production rates may be of the order of 50 B/D because of the considerable sand thickness open in some of the reservoirs. In the past, predictions of behavior of such reservoirs have been based on empirical extrapolation of the rate of production to the economic limit. Difficulties arise when new wells are drilled in the field or when production is artificially curtailed, since in such cases the decline rate of individual wells or leases changes and no clear trend can be detected. It was hoped that the present study would lead to improved methods for evaluation of such reservoirs. The study was initiated by building a scaled model for a particular field and by running a number of experiments on this model. Later a simple theory was developed which explained the laboratory results completely. The theory led, as shown below, to a hyperbolic-type decline equation which had been used previously' in a completely empirical manner. THEORY The General Case The problem to be treated here is the following: We are given a homogeneous cylindrical porous reservoir with exterior radius r, wellbore radius r., and height h,, containing, from the bottom up to a height hit oil, some gas, and interstitial water (see Fig. 1 A). The portion of the reservoir between K, and h, is filled with gas at low pressure, with residual oil, and with interstitial water. If at a time t = 0, the level of the oil in the wellbore is lowered to a height h,, what is the production rate from the reservoir at a time to The configuration within the reservoir at some instant

Jan 1, 1957

By B. M. Larsen

IN endeavoring to put the art of the steelmaker on a more scientific basis, as a means of securing closer control of the product, we must be severely critical of the basis of any theory we use. In particular, we must be careful to distinguish between factors that are primary and those of only secondary importance. The concentration relations that determine the slag-metal equilibria, which are usually more or less closely attained, are of course of primary significance, but a clear picture of the whole process requires that the actual rates of the several reactions be taken properly into account. At the high temperature of the steelmaking furnace, all reactions might be thought to be very rapid, but some of them in fact are not; the essential causes of this condition are important to a proper understanding of the process. This paper aims to present, and to justify, the viewpoint that the most significant reaction is the oxidation of carbon in the metal, the progress of which determines the oxygen pressure levels in slag and metal and produces stirring effects, all of which influence the course of the process as a whole. REACTION RATES AT STEELMAKING TEMPERATURES General experience in reaction rates makes it almost certain that at steelmaking temperatures equilibrium is attained practically instantaneously when the reactants are well distributed in a single liquid phase -that is, in the so-called homogeneous reactions. The actual slowness of some of the reactions in the open-hearth furnace must therefore be attributed to a relatively slow rate of diffusion within the slag or metal phase, which limits the rate at which the reactants can meet each other in the liquid steel or at its surface. That the reactions can be made to go with great rapidity, by proper mixing and stirring of the reacting phases, is indicated by the following illustrations: I. In the Bessemer process there is intimate contact between air and the whole mass of metal, and the reactions are complete in a few minutes. 2. Perrin1 has demonstrated that by pouring liquid steel into slag contained in a deep ladle, and thereby producing almost a slag-metal emulsion, the phosphorus or oxygen content of the steel is adjusted immediately. 3. Barret, Holbrook and Woods observed a quite rapid rate of desulphurization when powdered calcium carbide was stirred vigorously into liquid iron. 4. When a spoonful of liquid steel is poured into a mold containing aluminum wire, the formation and precipitation of alumina occurs in the fraction of a second required to freeze the surface layer of the tiny ingot. The first three examples all show that any means of increasing the effective surface between slag and metal and promoting intimate mixture of the reacting phases, thereby obviating the limitation imposed by diffusion, will enhance the speed of the steelmaking process.

Jan 1, 1941

By Gifford White

Considerable attention has been directed in recent years to methods of electric prospecting other than the conventional direct-current techniques. It has been extensively recognized that electrical data of a more general nature than that possible by direct-current methods might be useful in geophysical studies. To this end, a number of different types of electric currents have been employed, such as single-frequency alternating currents, square-topped periodic current waves,4 periodic surges of a less specific nature,s and suddenly applied direct current.1,2 Yet, to the author's knowledge, little analysis of these different types of driving currents has been made from the standpoint of network theory to determine just what typc of currents would give the most useful data, and, most important of all, to determine the relation of the data taken by one method to those of another. Without touching on the actual theoretical problem of how currents flow in the earth under specified boundary conditions, some very useful information can be obtained from the study of the fundamental integral equations of electrical networks, throwing light on the problem not ordinarily appreciated by the field worker. Some manipulation of the standard network equations will be made, with the sole purpose in mind of developing expressions leading to practical results. Suppose that four points in the earth have been located and it is wished to obtain the most useful type of electrical data by inserting current into two of them and measuring the potential developed between the other two. The first problem that arises is that of which pair of the four shall be chosen as current grounds. In the direct-current case, where only steady potentials are measured, the selection is of little consequence, but as soon as currents varying with time are used at the current grounds, a new effeet arises. The fact that a varying current is flowing in the current-carrying conductor between the current grounds means that magnetic and electric fields varying with time will be produced

Jan 1, 1940

By Thomas D. Bailey, Alec M. Crowell

Although natural gas was first discovered in Northwest Arkansas in 1887, . near Fort Smith, Sebastian County, the literature contains very little information on the region, which is separated distinctly from the oil area of Southern Arkansas. For that reason this brief and concise report is a summary of developments from discovery to the present time. Northwest Arkansas produced 5,736,-ooo,ooo cu. ft. of natural gas during 1942, the trend of production having been generally upward over the past five years, as is shown in Fig. I. Since 1904 a reserve of 237 billion cubic feet of natural gas has been discovered in Northwest Arkansas, of which approximately 162 billion cubic feet have been expended, leaving a reserve of approximately 75 billion cubic feet available as of Jan. 1, 1943. A prolific new field discovered in Pope County Oct. 23, 1942, will add to the reserve of the region materially. Per well reserves, over-all, are unusually high because of the practice of multiple completion. As yet no commercial deposits of oil have been discovered in Northwest Arkansas. but the gas deposits have proved of immense value industrially, principally in the processing of zinc ore mined in the local area as well as that imported from distant states. With the war, new interest in the exploitation of the metallic ores of the region lends new significance to the gas reserves tabulated herein. Geological Discussion The region covered in this report comprises the Arkansas Valley from Pope County weslward to the Arkansas-Oklahoma state line as shown in Fig. 2. This valley is a westward trending structural trough with sharp-topped ridges and mesa-like mountains rising above the valley's undulating surface. It is bounded on the north by the Ozark Highlands and on the south by the Ouachita Mountains. The sedimentary beds of the Arkansas Valley are composed mainly of noniossil-iferous shales and sandstones. The rocks contain a high content of carbonaceous material and many coal beds are found in the region. The Gxed carbon ratios (ratio of fixed carbon to volatile combustible matter of surface coals) are very high and average about 80 per cent over the region covered in this report. Little or no calcareous material is present. Rocks of the Arkansas Valley are sharply folded, and igneous intrusive rocks cut the sedimentary beds at a few places. The Arkansas Geological Survey' made a detailed reconnaissance survey of the Arkansas Valley province in 1927, the purpose being to delineate the major structural features (Fig. 3) and to point out the possibilities of discovering addi. tional gas deposits. More than fifty anticlines were mapped as a result of this survey. The information gained by this

Jan 1, 1943

By Alexander Bowie

In many places throughout the Western mountain plateau regions of the United States coal beds in place have been burned over very extensive areas, the fire evidently originating on the nakedly exposed outcrop of the coal bed and gradually burning its way into the bed for considerable distances under very heavy cover. The surface evidences of the burned-out coal beds are seen in the calcined and discolored rocks overlying the places of the outcrops. The greater the mass of the burned coal the higher the results of its combustion can be seen in the overlying strata. I have noted many instances of this condition in the States of South Dakota, Wyoming, Colorado, New Mexipo, and Arizona. In the lignite fields of Dakota and Wyoming I noted stretches of level country many square miles in extent where the surface rooks were roasted and vitrified by the burning of a great bed of lignite lying nearly level and with a light cover; this is probably the most favorable natural condition for the burning out of a coal bed. The less the depth of the rock covering overlying the coal bed, the better the chance for a continuous supply of air to the fire; but when the coal bed dips heavily into the ground, or even if level, if it passes under a hill or mountain which gives the bed a heavy covering of strata, the fire has more chances of being extinguished from natural causes than in the first condition described. The distance which a crop fire may extend into a coal field is very much influenced by the dip, the thickness of the coal bed, and the nature of the rock covering immediately overlying it. In reasoning on this subject, it would seem logical to assume in the case of a coal-bed cropping at the base of a hill and dipping into it, with an extensive drainage surface above the crop line, that a crop fire would be promptly extinguished by the caving in of the overlying strata and the precipitation of the rainfall from the drainage surface above the outcrop through the breaks formed in the caving strata. This consideration would be more or less effective according to the climate of the location and the nature of the overlying strata. In a humid climate where the rainfall was heavy the water from the natural precipitation alone would probably extinguish a crop fire before it could work its way very far under cover, but in an arid climate this preventive does not seem to be effective.

Jan 1, 1915