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By Raymond Mancha

THE purpose of the Coal Division's Committee on Ventilation is to cover one principal aspect of mine ventilation thoroughly each year, instead of attempting to touch upon several different subjects. The Committee for 1943 consists of four members besides the Chairman. Members, selected because of both knowledge of the current topic of mine ventilation, and diversity of occupation, are: Carel Robinson, consulting engineer with an operating background; T. G. Fear, chief engineer for the Hanna Coal Co., an operator of varied experience in mine ventilation; E. H. Denny, chief of the coal mine inspection division of the U. S. Bureau of Mines, obviously well qualified; and C. M. Smith, editor of Mechanization with a background of mine ventilation study as a member of the mining department of the University of Illinois, at present retained as a ventilation consultant by the Climax. Molybdenum Co. of Climax, Colo.

Jan 1, 1944

By J. T. Ryan

SiR Humphry Davy's epoch-making treatise delivered on Nov. 9, 1815, before the Philosophical Society of London, first announced and demonstrated a flame safety lamp for detecting methane in mine air. Coal mining was known in England as early as 1180, more than 600 years before the advent of a safe lighting and gas-detecting appliance. Mining, no doubt, took place first in outcrop coal, and danger from gas did not become apparent until the workings became deeper and more extensive. Davy's lamp did much to increase the safety of miners, and a modified Davy lamp is still widely used for detecting the presence and approximate amount of combustible gas in mine air. No factor in coal mining has improved more rapidly during the past 15 years than safety measures. This progress came about not only as a result of the workmen's compensation laws now in force in most of the states of the Union, but because the research work of the U. S. Bureau of Mines had demonstrated some dangers incident to coal mining which were not considered to be serious matters prior to that time. Electric power and explosives are necessary but potential hazards in American coal mines. A general mechanization program is now under way, while the mines are growing deeper and more extensive. Consequently ventilation problems are more complex and a demand has been created for positive detecting devices for carbon monoxide as well as methane. Scientists and manufacturers, working hand in hand during the past 10 years, have invented and developed appliances which make systematic and effective examination of mine air possible. The object of this paper is to describe briefly the approved testing devices in use today, with the hope that they may lead to the saving of life. Two Groups of Dangerous Coal Mine Gases Dangerous coal mine gases may be placed in two groups: (I) those that are dangerous because of their explosive properties, and (2) those that are dangerous because of their toxic properties. Methane (CH4) is the important gas of the first group, and in so-called gaseous mines constantly exudes from the coal and rock; it may accumulate and form an explosive mixture. The explosive range of methane-air mixtures is well defined. The low limit is 5 per cent., the high limit 15 per cent., and the most explosive

Jan 1, 1927

By S. W. Kessler, R. B. Pond

Metal specimens were solidified through a measured thermal gradient so a free surface and the liquid-solid interface could be examined. A line structure was observed on the surface and a hexagonal structure on the interface. A model to explain these forms is proposed. NUMEROUS observations of the dendrite form have been made both in nonmetallic and metallic systems. From these, extrapolations have been made as to the probable dendrite form in pure metals. Observations of the dendrite form in pure metals, nevertheless, have been scanty. In general, these observations have been made on the skeleton dendrite after the mother liquid has been drained from around it, and a mechanism of the formation of the dendrite has been postulated from this solid form. Recent investigations have been conducted in an endeavor to make a study of the formation of the dendrite in several pure metals and the effect of several variables on this mechanism and final form. For these investigations, an apparatus was designed and constructed as shown in Fig. 1. It consists of a talc block containing a half-cylindrical depression, the end of which terminates in the conical recess of a copper block having an external attachment for cooling. A heating coil extends the length of the mold just beneath the lower limits of the cavity. The entire cavity for holding metal is coated with a thin film of graphite. Six thermocouples are equally spaced in the cavity and under the graphite, and six microammeters indicate the temperatures at the particular thermocouple stations. Readings were taken of all meters at the same instant time measurements were taken by photographing the panel of microammeters and a stop watch which was started at the beginning of the run. It was possible with this apparatus to solidify metals through a measured thermal gradient and to observe the progression of the liquid-solid interface with time by following the formation of the dendrite markings in the surface of the solid material. These

Jan 1, 1952

By K. G. Colman

This text is intended to provide the operator and turn-key contractor with the basic data for sizing vibrating screens to be used in ore crushing plants. The basic capacities, modifying factors, etc. used in the area requirement calculations were developed empirically and modified to their present values based upon years of practical applications. It must be pointed out that screening is much more of an art than an exact science, however, the information presented here should provide for reasonably accurate screen sizing when applied to metallic ores .

Jan 1, 1978

By C. J. Bise, E. K. Albert

Mathematical modeling and computer simulation are the two primary techniques used for production analysis of underground coal mine layouts. Oftentimes, however, the selection between these two techniques is not based on an awareness of the level of effort needed for input formulation versus the suitability of the desired output. This paper will review mathematical modeling and two of the more prominent simulators (Virginia Tech's FACESIM and Penn State's UGMHS) used in underground coal mine production analysis. A hypothetical section will be analyzed by these programs and, based on the results of the aforementioned study, their advantages and disadvantages will be discussed.

Jan 1, 1985

By L. Delatour, K. Voltaire

This paper presents various aspects of the legal and economic settings that govern the exploration for mineral resources in Haiti.

Jan 1, 1980

By A. M. Adair

The effect of cathodically charging zone-refined iron with hydrogen and the resultant yield stress-grain size relationship has been investigated by tensile testing at -31°C. The resulting Petch plots (using a least-squares analysis) reveal a significant reduction in the slope and an increase in the intercept for specimens cathodically charged with hydrogen, regardless of whether the hydrogen is present during testing or is removed by evacuation. Other than surface blistering, the major effect of cathodically charging this material is to create occasional grain boundary cracks and thus presumably a large number of free dislocations at grain boundaries. These results are consistent with the hypothesis that the slope of the Petch plot is related to the stress required to activate dislocation sources at or near pain boundaries. While there is no significant effect of the presence of hydrogen on the lower yield stress of this material, the ductility is considerably reduced. After hydrogen removal by evacuation, the ductility recovers substantially and almost complete recovery of ductility is experienced by the smaller grain size specimens. THE influence of hydrogen on the mechanical properties of ferritic materials has received much attention throughout the history of the metallurgy profession. This interest has stemmed from the obvious importance of preventing the catastrophic failure of parts in service, and from the desire to determine what mechanism is responsible for the observed behavior. The various mechanisms proposed for hydrogen em-brittlement have been discussed in detail by Tetel-man,'who concludes that a combination of the applied stress and hydrogen pressure within voids best accounts for the many experimental observations reported. From a quite reasonable correlation of the strain aging and delayed-failure behavior of a variety of materials,2-7 Troiano and coworkers are of the opinion that the delayed-failure mechanism (slow strain rate embrittlement as well) is better explained as a lattice effect; solute elements diffuse to regions of high triaxial stress, form uncondensed atmospheres there, and effect a reduction in the cohesive strength of the lattice. Since hydrogen yield points8,9 have been observed in ferritic materials, and since the hydrogen embrittlement process may be related to strain aging, one further contribution to embrittlement could be hydrogen-dislocation interactions which make crack blunting by plastic deformation a more difficult process. The etch" relationship offers a means of comparing the relative ease of initiating and propagating plastic deformation in metals and alloys. In the present study, this relationship was used to compare the behavior of zone-refined iron in three conditions: uncharged, cathodically charged with hydrogen, and cathodically charged with hydrogen and evacuated. These Petch plots and the observed ductility parameters allowed a separation of the effects of the very presence of hydrogen and the act of cathodically charging hydrogen into this material. MATERIALS AND EXPERIMENTAL PROCEDURE An ingot of zone-refined iron was obtained from Battelle Memorial Institute which contained the following (typical) interstitial impurities in ppm: carbon, 10 * 5; nitrogen, 1; oxygen, 22; hydrogen, 0.9. The ingot was cold-reduced to a 1/2-in.-sq cross section, recrystallized 1 hr at 575°C, and then straight-rolled to a thickness of about 0.105 in. Tensile specimens were milled from the strip having a 1-in. gage length

Jan 1, 1967

By Ilmar Stöckel, Gösta Harlin, Agne Rustan

INTRODUCTION This chapter is a continuation of the studies by Rustan and Stockel (1979, 1980) on techniques for automating ventilation in Swedish mines and construction works. The studies have been financed by the Swedish Board of Technical Development. As a result of the studies it has been recommended that a good solution to diesel exhaust emission would be automatic, step by step control of the fans near the working place. Diesel vehicles are the major polluters underground in the mines. Therefore, we have suggested that diesel vehicles regulate the fans The goal of the continued study has been to find a way for active diesel vehicles to start and stop gallery fans at both intake and return air. In this paper different methods for activating fans are discussed. The best methods are chosen and tested in the mine. In this study we have found that change of temperature is an inexpensive and effective way to start and stop crosscut fans in sublevel caving and radio signals seem to be an attractive system for starting and stopping gallery fans . This work has been done in close collaboration between LKAB in Kiruna and the University of Luleå, Divisions of Electronics and of Mining and Rock Excavation. An advisory group for the project has been established with ventilation experts from the mines, representatives of the local mine workers' unions, and authorities from the local offices of Governmental Inspection of the Workers Safety. VENTILATION SYSTEM STUDIED In the project the ventilation system at LKAB in Kiruna was studied. The mining method used is sublevel caving with 9-13 m slice height. The air above ground is heated in winter by hot water and the main fans push the air down to a main distribution level along the 4000 m long and about 100 m wide ore body. From the distribution level, air is taken through shafts down to the sublevels, where it is pushed through the levels by local gallery fans on both the intake and return sides, Fig. 1.

Jan 1, 1981

By S. S. Lau

The authors of the previous comment stated that Dorn and Rajnak33 and others34-40 concluded that "agreement with this function [(t'/tp) -f(Un/2Un) = T/Tc} may be used as a criterion for that (the Peierls) mechanism of deformation". In contrast, however, Dorn and Rajnak33 and others34-40 never made such a statement. In order to clarify the issues involved it is appropriate to recapitulate the conditions that must be satisfied in order to suggest that some deformation process might obey the Peierls mechanism: 1) Within permissible variations due to changes in the slope of the Peierls hill the T*/Tp - T/Tc relationship must be obeyed. Although some mechanisms, e.g.. solute atom stress field, recombination of dissociated partials in bcc metals, intersection of dissociated dislocations, and so forth, give about the same t* - T relationship, other mechanisms, such as cross slip, disruption of attractive junctions, climb, motion of jogged screw dislocations, and so forth, give distinctly different t*-T relationships. On this basis some distinction can be made of the various mechanisms. 2) An important feature of the Peierls mechanism concerns its physical origin based on the nucleation of pairs of kinks. The value of T* at 0°K increases with the density of dislocation (i.e. , cold work) for the intersection mechanism and it increases with the square root of the atomic fraction of solute atoms in the solute atom interaction mechanism. In contrast the value of t* at 0°k, for the Peierls mechanism which depends only on the line energy and the shape of the Peierls hills. is independent of cold working and the square root of the solute atom concentration. These differences have been employed by various investigators for elimination of a few other possible mechanisms. On the other hand it is not possible to eliminate all mechanisms, e.g., the recombination of dissociated dislocations in bcc metals, and so forth, on this basis alone. 3) Further discrimination between possible mechanisms is based on the activation volume. For the in-

Jan 1, 1968

By Homer W. Riley

ANTHRACITE SMALL power-driven, toothed, cast-iron rolls were used first to break anthracite in 1844. Prior to that time, men with hammers, who stood on perforated cast-iron plates, broke the large lumps into commercial sizes. In order to convert run-of-mine into the various sizes required by the anthracite industry, about 20 million tons must be broken, annually, into smaller sizes. This phase of anthracite preparation is of major importance, because the degradation accompanying reduction in coal sizes should be kept at a minimum. The exclusive use of toothed rolls for that purpose indicates that comminution by rolls is the best solution of the problem. Many improvements have been made in tooth design, but the most important was a reduction of the peripheral speed of the rolls from 1000 to 300 ft. per minute. The higher speed was based upon and approximated the velocity of a falling piece of coal when it entered the rolls, Exhaustive roll tests at the slower speed showed that the same size reduction could be affected with less degradation. The adoption, therefore, of slow-speed, compound geared rolls, especially for breaking the larger sizes, became quite general after 1912. A high-speed roll is shown in Fig. 1 and a slow-speed roll in Fig. 2. Anthracite Crushing Problems.-Crushing anthracite presents the problem of selecting a series of rolls that will produce the greatest percentage of the prepared sizes of nut and over. The size distributions to be expected are shown in Table 1. Coal breaking and crushing practices in anthracite breakers involve the use of equipment for comminuting the following classes of material: 1. Run-of-mine-plus 6 ½ -in. coal. 2. Sized coal-steamboat, broken, egg, stove, nut, and pea. 3. Flat coal--coal that is flat and hence not suitable for the market. 4. Bone--a piece of laminated coal and slate, crushed for the purpose of reclaiming the coal. 5. Breaker refuse, reduced to a size suitable for flushing into a mine for back-filling purposes.

Jan 1, 1950

By Albert E. Wiggin, Frederick Laist

Early ill 1914 it was decided to test, on a fairly large scale, the treatment by flotation of Anaconda slime and mill tailing. For this purpose a standard-type Minerals Separation machine was installed at the Washoe Reduction Works during May and June, 1914. This was followed by the installation of a full-size Callow pneumatic machine plant. Experiments were also made, on a smaller scale, with the Froment, the Towne, the Fields, and the Anaconda flotation machines. The last-named machine was developed at this plant. In addition to the tests made in the standard-type Minerals Separation machine some tests were made using a Minerals Separation machine of the sub-aeration type. During the series of experiments a large variety of oils was tested. Experiments were also conducted using both round-table feed and tailing to determine whether it would be better to displace the round tables by flotation for the treatment of the slime, or to supplement the round tables by flotation of the round-table tailing. A series of tests was also made on the treatment of the mill tailing by grinding followed by flotation to determine the relative merits of flotation and leaching for the treatment of this product. In addition, flotation tests were made on mixtures of mill tailing and slime. The round-table feed referred to above is the total slime from the mill. It contains about 35 per cent. colloidal solids and approximately 90 to 95 per cent. of the total solids will pass through 200 mesh (0.067 mm.). It assays from 2.3 to 2.6 per cent. Cu. The mill tailing referred to above is the total discard from the mill, exclusive of the slime. It is all finer than 2 mm. and about 90 to 95 per cent. will remain on 0.25 mm. It assays about 0.60 per cent. Cu. A brief summary of the experimental flotation results follows:

Jan 1, 1917

By Ben F. Dickerson

Mineral exploration programs have often experienced mismanagement in the decision-making process, and these errors have consequently resulted in stockholder losses. Unfortunately, the events leading to these errors are little known and rarely studied, since managers aren't prone to publicizing their mistakes. However, a bit of magnified hindsight may serve to identify some of the problems. It is interesting to note that there does not seem to be a generally agreed-upon definition of the role and function of exploration management. Several articles have addressed this subject, written by both academic and industry exploration personnel. Two apparent thought trends can be observed: First, the theoreticians insist that modern scientific management principles can be directly applied, without modification, to mineral exploration. However, when one searches for the rules, the proponents rapidly retreat behind the computers and talk learnedly of management information systems and game theory.

Jan 6, 1978

NEW MEMBERS The following list comprises the names of those persons who became members during the period July 10 to Aug. 10, 1915: Members ALBERTSON, MAURICE MERTON, Mine Surveyor, Mining Corporation of Canada, Cobalt, Ont., Canada. ARMSTRONG, GEORGE CHANDLER Mgr., Indian Refining Co., Lawrenceville, Ill. BARBER, MAX HAYDEN, Min. Engr Supt., Crosby Mine, Nashwauk, Minn. BARNESON, JOHN Merchant, 310 Sansome St., San Francisco, Cal. BENSEL, JOHN A., Cons. Engr 111 Broadway, New York, N. Y . BORGESON, ANSHELM CYRUS, fin. Engr Shenango Mule, Chisholm, Minn. BROOKS, CHARLES PETER, Min. Engr 228 Dooly Bldg., Salt, Lake City, Utah. BROWN, FRANK HAROLD, U'011',. Min. Engr., Federal Co., Inc., 50 Broad St., New York, N. Y. CLARK, DOUGLAS Kellogg, Idaho.

Jan 9, 1915

By N. T. Cotman, C. H. Pickering, P. B. Crawford

A beat-conduction model has been developed to study the flow of fluids in a stratified oil reservoir which is being subjected to unsteady-state depletion. To simulate stratification, plates of different metals were joined together so that cross flow could occur between strata. A description of the model, plate construction and necessary instruments is included. The data indicate that stratified oil reservoirs experiencing cross flow may be treated as a single, homogeneous, producing sand having properties intermediate between those of the layers making up the system. A technique for averaging core-analysis data to arrive at the proper average value of rock permeability and porosity is presented INTRODUCTION Although oil has been produced from reservoirs for 100 years and reservoir injection processes have been undertaken for 40 years, the industry is still inadequately informed on the problem of reservoir inhomogeneities. Stratification is perhaps the best-known type of reservoir heterogeneity. Urenl discussed the possible significance of this nonuniformity in his 1927 paper on the theoretical aspects of water flooding. Since this time the problem of vertical permeability variations has been the subject of much discussion and numerous papers. Levorsen2 simply describes the origin of layered beds in his Geology of Petroleum. Some beds are field-wide and may be traced from well to well, while others apparently pinch-out and become discontinuous. In addition, the physical characteristics of a layer may vary from place to place. For these reasons, a stratified system is not easily defined. In calculations involving oil reservoirs in which permeabi1ities vary, methods presently used contain many simplifying assumptions. The reservoir frequently is considered as consisting of permeable layers, each of uniform vertical and lateral permeability and each behaving as if separated from adjacent layers by thin impermeable layers. Other assumptions frequently made in reservoir calculations are steady-state flow conditions, unit mobility ratio, linear geometry, average or homogeneous porosity, and negligible capillary-pressure and gravity effects. Muskat3 has. developed solutions to the stratification problem for mobility ratios other than unity for both linear and exponential permeability distributions. He assumes lateral uniformity and continuity of all productive strata and does not consider porosity. This study will take into account transient effects, cross flow and varying porosity, as well as the variations in permeability, by means of a heat analogy. Muskat5 has shown the similarity of the equations which describe the flow of fluids in a porous medium to the flow of heat through a solid. Landrum, et al,6 made an analogy between the flow of fluid in an unsymmetrical reservoir and the conduction of heat in a similarly shaped metal plate. This analogy is summarized briefly as follows. If fluid is produced from an oil reservoir above the bubble point, the resulting pressure distribution will be identical to the temperature which would result in a metal or heat-conducting plate if heat were similarly removed. This means that a study of heat flow in stratified thermal models will behave like fluid flow in stratified oil reservoirs. For mathematical correspondencies, set- Ref. 6. The fluid mobility k/p is proportional to the thermal conductivity, and the porosity-times-compressibility product is proportional to the density times specific heat of the thermal plate. EXPERIMENTAL EQUIPMENT AND PROCEDURE The stratified reservoir model used in this study is illustrated schematically in Fig. 1. A Leeds and Northrup Speedomax Type G temperature recorder

By R. K. Buhr, H. Thresh, M. Bergeron, F. Weinberg

The microsegregation of nickel and chromium in directionally solidified AISI 4340 steel castings has been measured using electron probe microanalysis. Minimum concentrations were observed to occur at the center of the dendrite stalks, as reported previously. However, the position of the maximum concentrations could not be determined from the dendrite configuration. An etching technique has been developed which shows the position of maximum concentration. Measurements were made of the distribution of nickel and chromium in the dendritic structure. The ratio of maximum to minimum concentration was determined as a function of primary dendrite arm spacing for both as-cast and partially homogenized materials. The results are compared with observations reported in the literatuve. A S part of an investigation of solute segregation in directionally solidified AISI 4340 steel casting, electron probe microanalysis was used to measure the distribution of nickel and chromium in the dendritically segregated material. This complemented the observations on the segregation of radioactive phosphorus obtained by autoradiographic techniques in the same castings.' Kattamis and I?lemings2 have reported similar measurements, using electron probe microanalysis, on dendritically segregated AISI 4340 steels. They found minimum solute concentrations occurred at the center of dendrites, maximum concentrations occurred in the center of interdendritic regions, for symmetrically oriented dendrites, and a regular variation of concentration within dendrite arms. The ratio of maximum to minimum concentration was found to be essentially independent of position in the castings, except near the chill surface where it was somewhat higher. Assuming complete diffusion in the liquid and no diffusion in the solid during freezing, they considered that isoconcentration curves in the steel were homothetic. As a result, isoconcentration curves of the various elements, contour surfaces of dendrites produced by isothermal-transformation studies, and the contour of the solid-liquid interface would all be similar, and could be superimposed by a uniform expansion or contraction of the contours. Preliminary results of the present investigation suggested that isoconcentration curves were not homothetic. It was also evident that points of maximum concentration could not be predicted from the dendrite configuration. Since the ratio of maximum to minimum concentration appeared to be an important parameter in defining the overall segregation in a casting, other techniques for determining the point of maximum concentration were investigated. In addition the overall solute distribution associated with the dendritic structure was examined for both nickel and chromium, and the consistency of the distribution for neighboring dendrites was determined. METHOD Fifty-pound heats of AISI 4340 steel were cast in a manner similar to that used by Flemings et al3 with a water-cooled copper base plate and exothermic sides and top. The nominal composition of the material was C, 0.41 pct; Mn, 0.66; Si, 0.35; S, 0.012; P, 0.010; Ni, 1.88; Cr, 0.95; Mo, 0.28. The steel solidified directionally from the chill surface, with a dendritic structure which increased in dendrite arm spacing with increased distance from the chill. Results of the general investigation of the cast structure and segregation of radioactive phosphorus in these castings have been reported elsewhere.' For the present measurements, sections were cut from the casting at several distances from the chill surface. The sections were subsequently heat-treated, mounted, and then polished on a plane perpendicular to the general freezing direction of the casting. Electron probe microanalysis was carried out with the JEOL-JXA3 microprobe using a voltage of 25 kev and beam current of 0.15 µa. The take-off angle is 22 deg. Quartz crystals were used in the spectrometers and measurements made for Ka radiation from both nickel and chromium simultaneously. A thin layer of carbon was deposited on all specimen surfaces prior to examination in the microprobe. Early measurements were made on polished surfaces, with indentation marks produced by a hardness tester to indicate the area of interest. It was found desirable to use etched surfaces, as opposed to polished surfaces, to reduce sample preparation time and more readily relate the microprobe scan to the structure. To determine if this could be done, without introducing significant errors, a series of measurements were made on polished and etched surfaces of the same specimen. Both polished and etched surfaces produced similar results within normal scatter as shown in the observations. Subsequent measurements were then made on etched surfaces. Measurements with the microprobe analyzer were made by point counting, for periods of 100 sec, at 10-µ intervals. Ten-second counts were made on pure nickel and chromium standards, incorporated in the specimen mount before and after each set of measurements. The results were adjusted for background, then corrected for dead time using the expression:

Jan 1, 1969

By R. J. Woody

Design of the most economic continuous counter-current decantation (CCD) circuit is based on selection of the number of stages and the wash volume that will give the minimum summation of the following items: 1) Capital and operating costs of the CCD circuit. 2) Capital and operating costs of the precipitation circuit. 3) Value of the dissolved product lost.

Jan 1, 1959

By B. S. Gottfried

This paper is concerned with possible transport mechanisms which occur during segregated burning (i.e., burning in an oil reservoir in which the oil-bearing formation is overlain by a "clean" porous zone containing only gas). ,Two analytical models are presented. In the first, burning is assumed to occur at the gas-oil interface, and the dominant mechanism is taken to be the rate at which oxygen diffuses to the interface. The second model assumes that combustion occurs within the clean zone, with the dominant mechanism being the mechanism of fuel deposition from the oil-bearing formation to the clean zone. ,Comparison of the results of the analyses with limited experimental data indicates that the latter mechanism is much more plausible. Both models are idealized representations of the actual process and are somewhat conjectural, however, owing to the lack of more definitive laboratory or field data. INTRODUCTION In recent years there has been considerable theoretical and experimental research directed toward understanding the recovery of crude oil by underground combustion. Although two different recovery schemes have been proposed, known as forward and reverse combustion, it is only forward combustion that shows promise of becoming a practical recovery technique.17 Most of the analyses of the forward combustion process have considered it to be pistonlike; i.e., oil is displaced by a vertical combustion zone which, with its ensuing gases, pushes die oil forward as the flame front is propagated through the reservoir.l-8,ll,l2,14-16 However, information gained in field pilot studies indicates that, at least to a certain extent, forward combustion proceeds in a segregated manner in oil reservoirs.10 An ideal segregated system is one in which the oil-bearing formation is overlain by a "clean" porous zone containing only gas. The location of the combustion zone in such a system is not immediately evident, although combustion is believed to occur either at the gas-oil interface or within the clean zone. In either case, the combustion zone may be horizontal and it moves in parallel rather than in series with the produced oil. The purpose of this paper is to explore the likely mechanisms by which segregated burning can occur, and to determine the sensitivity of the resulting models to changes in various physical parameters. Two governing mechanisms are considered: the case of a horizontal combustion zone at the gas-oil interface with the rate of combustion governed by the rate at which oxygen diffuses to the interface, and the case of combustion within the clean zone with the combustion process controlled by the transport of fuel from the oil-bearing formation to the clean zone. Both models are somewhat hypothetical and involve considerable simplification of the actual process. However, the results allow some preliminary understanding of segregated burning which is useful in the absence of more definitive laboratory or field pilot data.

Jan 1, 1967

By Barnabas Bryan

During the boom period of 1928 and 1929, several oil companies took advantage of high security prices to sell stocks, thereby securing money for the company very cheaply. Few if any of those companies realized that the money received was not at all cheap in view of the fact that it was for investment in fixed assets at inflated prices. Suppose a company borrowed twenty millions of dollars to expand its marketing facilities during the boom. It diluted its capital and acquired fixed property which could not earn its interest requirements during the following deflation and therefore consumed income from other company activities. The company also had to stand the deflation in the capital value of all the property it bought. Since the mistaken expansion during the boom accelerated the decline in net income during deflation, the financial position of the company was harmed in proportion to the amount of that expansion. Thus the company was unable to get money to buy fixed assets in the depression when all property is cheap. The same condition holds for the company that sold common stock for the purpose of developing potential production in a newly discovered oil field. Regardless of what the ultimate value of the new field may be, potential production does not increase the net income of the company. The difficulty of meeting the enlarged dividend requirements due to the increased number of shares outstanding impairs the financial position of the company during deflation in some relation to the probability of decreased dividends. This company also is not in a position to expand during the depression when properties and companies can be bought for a fraction of their real value. Expansion of fixed assets during boom times has been the ruin of many otherwise good companies. Some of those which most extensively bought property during the post-war boom have not yet recovered. A number of cases could be cited in sugar, leather, fertilizer and wool. This does not seem to be governed by the quality of the property bought, for examination shows the assets to have been of individual high quality in many cases. When recovery is long deferred it is likely to be true, as in sugar or textiles, that the industry has a large "potential" capacity for overproduction.

Jan 1, 1931

By A. B. Kinzel

THE demands of the petroleum and chemical industries for steels to be used in pressure vessels and similar structures at artificially low tempera-tures are continually increasing, and the writing of proper specifications with suitable tests becomes increasingly important. Likewise, the selec-tion of suitable steels for such applications is of increasing concern to the metallurgist. It is generally recognized that highly alloyed steels of the austenitic stainless type retain their properties even at very low tempera-tures and represent the best technological solution of the low-temperature steel problem. However, in many instances less expensive carbon or low-alloy steels suitable for service within limited temperature ranges are available. The problem thus becomes one of defining the various factors involved in the production and fabrication of these less expensive steels and determining the temperature ranges in which their properties justify engineering application. Most of the applications involve welded structures, and the heat effect of welding as well as the nature of the weld metal are matters of prime concern. The first problem that the metallurgist faces is the determination of the type of test to be used as a criterion of the performance of the steel in low-temperature service. It has been generally recognized that the static properties of steel as determined in the ordinary tensile test undergo a gradual and relatively slight change as the temperature of test is lowered in the range of current interest; i.e., from room temperature to minus 120° C. It is further generally recognized that the behavior of steel under impact involving notch sensitivity is definitely affected at the lower temperatures. While the major subject of this paper is the effect of grain-refining deoxidizers, of low-alloy additions and of welding on the low-temperature notched-bar impact properties, an inquiry into the general behavior of steel under low-temperature impact testing is included. This is a pertinent portion of the investigation and the results thereof are

Jan 1, 1937

By AIME AIME

THE 131st meeting of the American Institute of Mining and Metallurgical Engineers was held in New York on Feb. 16 to 20, 1925, with the largest registration of any previous meeting, the total being 1320 compared to 1276 in 1924. The technical sessions were more largely attended and aroused more discussion than ever before. There were joint meetings with the Mining Section of the National Safety Council, under the auspices of the Industrial Relations Committee of the Institute and two very important lectures, the Howe Memorial Lecture, under the auspices of the Iron and Steel Committee, and the lecture by Dr. Carl Benedicks, of Sweden, on Corrosion, under the auspices of the Institute of Metals Division. The Petroleum Division conducted its annual Symposium on Oil which will be published later in book form. At the annual business meeting on Feb. 17, the following ticket was elected, and the reports of the President, Treasurer, and Secretary 'were presented:

Jan 1, 1925