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By H. J. de Haan, J. van Lookeren

In view of their size and favorable characteristics, Shell's heavy-oil fields on the eastern coast of Lake Maracaibo, Venezuela — known as the "Bolivar Coast" — are obvious candidates for the application of thermal recovery methods. During the last decade various methods have been tested, such as steam drive,', steam soak and in-situ combustion.3 Steam soak was discovered as a promising production method rather accidentally in 1969, during early steam drive testing in the Mene Grande Tar Sands1 When steam erupted at the surface due to breakdown of the overburden, the injection wells were back-flowed to relieve the reservoir pressure. This resulted in high oil production rates, all the more impressive because the reservoir is unproducible by primary means. It was concluded that injection of limited amounts of steam might be a very effective method for stimulation of heavy-oil wells. To obtain information that would be more widely applicable, testing of the process was continued in the eastern part of the Tia Juana field (Fig. 1). Here even more favorable results were obtained than in Mene Grande. This created sufficient confidence to prompt a large-scale project, which was considered essential for an adequate evaluation of ultimate recovery, steam requirements, mechanical problems and economic prospects. To obtain an early answer on the ultimate recovery a fairly depleted area was selected in the western part of the same field ("A" in Fig. 1). The first steam was injected in March, 1964. This paper describes the performance until the end of 1966. The production mechanism and well inflow performance are discussed in some detail. In view of the favorable results obtained so far, steam soak operations have expanded considerably since the start of this project. Presently, five other projects are under way, of which two are about the same size as the one under discussion, with further extensions being programmed. Description of the Project Reservoir Data Shell's part of the Main Tia Juana reservoir has a proven area of 8,800 acres and an average net oil sand thickness of 130 ft. It contained an initial quantity of 2,750 million bbl of stock tank oil (STOIIP), with an API gravity ranging from 10 to 15 API and a viscosity of 100 to 10,000 cp (at 122F). As a geological unit it is known locally as the Lower Lagun-illas member of the Lagunillas formation, which is early Miocene in age. The sand bodies are believed to be distributary channel sands deposited in a lower coastal plain. Most of the channel sands have lateral and some vertical communication. The field was developed mainly in the period from 1936 to 1950. The ultimate primary recovery is estimated at 18.1 percent of STOIIP, of which 12.5 percent STOIIP had been produced by the end of 1963 from some 540 wells. By then the average pressure had decreased from an initial value of 960 to 550

Jan 1, 1970

By C. F. Weinaug, R. W. Farley, J. F. Wolfe

A rapid, accurate method for predicting the dew points of gas condensate systems and their subsequent normal and retrograde phase behavior with pressure decline has been developed. The method predicts dewpoint pressure, volume percent liquid, condensate content of produced gas, and the liquid and gas compositions at pressures below the dewpoint pressure. Use of a modified form of the BWR equation of state, which was established by regression calculations on experimental data from several gas condensates, provides depletion behavior predictions that are significantly improved over predictions using K-values based on convergence pressures and Standing's correlation for density. INTRODUCTION Prediction of complex hydrocarbon-mixture thermodynamics is fundamental to reservoir and gas process engineering. In particular, accurate descriptions of phase behavior are needed to plan production operations for gas-condensate reservoirs. Although analysis of reservoir behavior during producing and cycling operations can be made for simple reservoir models, extensions of these studies to more complex reservoir systems are still difficult, both with regard to numerical techniques and the phase behavior of the fluids. This report presents a mathematical method for handling the complex phase relationships encountered in retrograde condensates; it represents an advance in reservoir behavior technology in that it will aid the development of closed-form mathematical representations of total production systems. A typical phase diagram for a complex hydrocarbon mixture is shown in Fig. 1. When the reservoir temperature T, is higher than the critical temperature Tc, and lower than the critical-condensation temperature Tct' the mixture is a gas condensate. Decreasing the pressure on a condensate while maintaining nearly constant temperature will result in two phases forming at the dew point. Further decrease in pressure will cause additional liquids to be formed. This phenomenon is called retrograde condensation. As pressure continues to decrease, normal phase behavior regions are encountered (liquid vaporizes as the pressure decreases) until the low-pressure dew point is encountered. When a gas-condensate reservoir is produced, gas is withdrawn and the volume of fluids in the reservoir remains nearly constant as the pressure declines. Heavier components tend to accumulate in the liquid phase as a result of retrograde condensation, while lighter components tend to concentrate in the vapor phase. Thus, as the gas is produced the composition of the gas and the condensate

Jan 1, 1970

By A. B. Cook, C. J. Walker, G. B. Spencer

Although water will displace oil from a petroleum reservoir to a greater extent than gas will, there are some reservoirs in which gas rather than water should be used for pressure maintenance. This is indicated by the high-percentage oil recovery in the case history reports on the Pickton field1 in East Texas and the Raleigh field2 in Mississippi. In gas cycling, total oil recovery includes vaporized products from the immobile oil in addition to oil produced by displacement. If a large part of the immobile oil is vaporized, total oil recovery may be higher than that obtainable from pressure maintenance by water injection. However, the amount of immobile oil vaporized may range from almost 0 to 100 percent, and no simple and reliable method has been presented in the literature for calculating oil vaporization. Development of such a method was the purpose of this study. Several papers concerning the calculation of oil vaporization have been published,3 6 and each is based on the concept dealing with K values — equilibrium constants for the various components in reservoir oils. (K for a component in a system of vapor and liquid in equilibrium is the mole fraction in the vapor phase divided by the mole fraction in the liquid phase.) This appears to be the most logical approach. Yet, the problem is too great for a perfect solution, even with modem laboratories to analyze oils and high-speed digital computers to perform calculations; the number of components in reservoir oils is too large. Because of their complexity no two reservoir oils are exactly alike. Also, K values change not only with variations in pressure and temperature but also with composition of the reservoir oil. In addition, during gas cycling, the lighter hydrocarbons tend to vaporize first. Thus, the reservoir oil becomes more dense and less volatile as gas cycling continues. Furthermore, the greatest amount of oil vaporization occurs near the injection well. Therefore, a simplified method is required for calculating oil vaporization because a rigorous method is not practical. The present methods of calculating vaporization generally require knowledge of the reservoir oil composition in which the mole fractions of the lighter components through hexanes are given; the remaining oil is described as C, + (heptanes and others of greater molecular weights). Assigning one K value for the C,+ system provides the simplest solution, but this incorrectly assumes that K for C, + does not change as gas cycling continues. This assumption can cause large errors because the K value may become less than a thousandth of the original after a large amount of oil vaporization. Another way to solve the problem is to determine changing K values for C, + according to how much of the C, + has been vaporized. To determine these values a sample of the reservoir oil is injected into a pressure-volume cell, and dry gas is batched in and out of the cell. Appropriate measurements and tests are made to determine K

Jan 1, 1970

By P. T. Allsman

INTRODUCTION The honor of being the recipient of the Mining Society's Daniel C. Jackling Award for 1966 imposes on me the responsibility to search for the subject that I would be best qualified to discuss. It seems that my experience in the mineral industry — nearly 15 years in private and 30 years in public employment — should uniquely qualify me to comment upon the relationships between the mining industry, mineral engineering as a profession, and government, and the changing economic, technologic, political and social changes that dictate their relationships. Such conditions, the increasing knowledge of the world mineral resource base, the greater demands of an expanding population with a rising standard of living, shall be evaluated with respect to our profession — mineral engineering. In all of these forty or so years, I have been in close touch with many phases of the mineral and energy resource industries, especially those of the United States. Particularly during the past 10 years, I have had a ringside seat at the "goings on" in Washington. During all of this period I have observed and analyzed many of the problems of the industry and its relations with the government. During the past few years, I have had increased opportunity for doing research and have found a need to learn something about the mathematical techniques that are undergoing such a revival since electronic computers were developed. One of these techniques is multivariate analysis, which is a system for correlating a large number of complex variables. By applying this technique to the seemingly chaotic present-day situation, there emerges a course of steady improvement in the minerals resource industries that wars, depressions, and political strife have failed to obstruct for long. In short, I advocate a need for new concepts in mineral engineering to cope with the changes, pos- sibly adding many more specialized areas on one end of the spectrum, and broad engineer-generalist approaches at the other. The meeting place shall be where the intricate mineral resource problems at the frontier of knowledge merge into the socio-techno-logical problems of the world. HISTORICAL INVOLVEMENT OF GOVERNMENT IN MINERAL RESOURCE PROBLEMS Involvement of government in mineral resource problems undoubtedly is as old as government itself. But passage of the Mining Act of 1866, superseded by the Act of 1872, was the first major entry of our Federal Government into the problems of mining. Passage of the law was necessary to resolve many conflicting claims and disputes in mining. The General Mining Law of 1872 and the Mineral Leasing Laws of 1920 apply to millions of acres of public lands and to certain privately owned land on which the mineral rights have been reserved to the Federal Government. The extensive involvement of government in the mineral industry business today often comes as a shock to the mineral engineer who has begun to climb the ladder to the top in his company. He is often poorly prepared to cope with the situation and becomes frustrated and even hostile. Better knowledge of the role of government perhaps would ease his situation. In our political system, private industry is responsible for producing minerals. To make certain that the production is adequate for a peace-time economy, and to guarantee the Nation's security in an emergency, the Federal Government finds it expedient to develop policy and engage in regulatory, educational, and research activities. A few examples will illustrate the varied role of government in relation to mineral problems. In varying degrees many agencies of the Executive Branch of Government have responsibilities that influence the functioning of the mineral and energy industries. In addition, of course, Congress, the Judiciary, and State and local governments exercise great influence. The Department of the Interior is primarily responsible for activities to promote the development and conservation of mineral and fuel resources, and the

Jan 1, 1967

By H. W. Fleming, R. R. Brooks

The Clearwater Deposit, a small occurrence of massive-sulphide mineralization enclosed in an envelope of disseminated-sulphide mineralization, was discovered as a result of an aeroelectromagnetic survey in New Brunswick in 1955. Subsequently, additional flights were made over the deposit and various ground follow-up methods were employed to ascertain the nature of their response. All methods proved to be capable of indicating the occurrence with varying degrees of precision. This paper is a presentation and a discussion of the magnetic and electromagnetic data, both airborne and ground, and the self-potential data obtained over this deposit. The attention of Canadian mining exploration companies was initially focussed on New Brunswick by the discovery, in 1953, of the Brunswick ore body. Ground electromagnetic surveys were of considerable assistance in locating and developing this deposit. In the following year, 1954, the Heath Steele base-metal deposits were discovered by employing an airborne electromagnetic device and ground electromagnetic surveys to follow-up the airborne indications. These discoveries demonstrated clearly that both airborne and ground electromagnetic techniques were applicable for locating the near-surface deposits of massive sulphides present in this region. Airborne electromagnetic equipment became available on a contract basis through Aeromagnetic Surveys Limited early in 1955 and was used extensively thereafter throughout a large portion of northern New Brunswick. It was as a result of one of these surveys with Aeromagnetic Surveys Limited equipment in the summer of 1955 that the Clearwater Deposit was detected. The airborne anomaly was located on the ground by means of an electromagnetic survey using a Swedish Slingram unit. During 1956, the region was investigated more thoroughly- in the hope that other sulphide bodies might be located. Airborne electromagnetic coverage was extended and the Clearwater Deposit itself was used as a testing ground for the various methods and types of equipment currently in use in New Brunswick. In this paper com prative data are presented for the airborne magnetic, airborne electromagnetic, ground magnetic and ground electromagnetic surveys over this deposit. The ground electromagnetic instruments used were the McPhar vertical-loop unit and the Slingram and Boliden horizontal-loop units. Self-potential surveys were carried out with a McPhar unit. From the geophysical point of view, all ground electrical methods employed indicated the presence and the extent of the massive-sulphide mineralization with a good degree of accuracy. The horizontal-loop methods however, defined the contacts more precisely as is to be expected when dealing with a flatly-dipping

Jan 1, 1961

By Reginald E. Hore

I. INTRODUCTION. SINCE the discovery of silver at Cobalt, Ontario, in 1903 more than 100,000,000 oz. of silver have been produced b: the mines in the Nipissing district, and there is reason to believe that at least as much more will be produced in the next five years. The estimated value of the aggregate output o ore to the end of 1910 is $48,327,280. The ore yielded 93,977,833, oz. of silver and was mined at a net profit of about $26,000,000. For 1910 the production was 30,558,825 oz. valued at $15,436,894, and yielding a profit of about $9,000',000 The details of the production of the Cobalt district for the years 1904 to 1909, inclusive, are given in Table I. TABLE I.-Silver-Production of the Cobalt District, 1904 to 1909 SMELTING-ORE. Production. Value. Silver-Content. Value Per Ton Ounces. Oz. Per Ton. 1904 206,875 $111,887 1,309 $708 1905.:.... 2,451,356 1,360,503 1,143 634 1906 5,401,766 3,667,551 1,013 687 1907 10,023,311 6,155,391 677 416 1908 18,022,480 8,468,293 736 363 1909 22,436,355 10,809,872 809 389 CONCENTRATES. 1908 1,415,395 $665,085 1,240 585 1909 3,461,470 1,651,704 1,174 559 The shipments from Cobalt are in the form of smelting-ore, concentrates from milling-ore, and bullion. The smelting-or( is largely high grade, averaging about 3,000 oz. per ton- A

May 1, 1911

By Robert H. Richards

(Pittsburg Meeting, March, 1910.) THIS is in part a review paper, indicating the various steps that have been taken in developing hindered-settling apparatus, some of the standard data that have been obtained, and some of the conclusions one is led to as to the effect of it in improving concentrating-methods and machinery, and in part it brings in some unpublished work. CAUSES OF LOSS IN ORE-CONCENTRATION. In making a study of the separation of valuable minerals from the waste gangue, particularly by water concentrators, it is necessary to define, first of all, what are the causes of-loss that are likely to interfere with the concentration. Having made this definition; we can then study to see in what way the machines make their losses, and plan remedies for them in an intelligent way. Losses may be stated to occur as included grains, as flat or long grains, as fine free mineral, and as absolute slime. We will take, these up one by one, as follows: Included Grains.-Fig. 1 shows by a set of diagrams how included grains may occur: first, where the heavy mineral grains attached to the quartz are of large size; secondly, where they are of small size ; and thirdly, where very fine particles of heavy mineral are included in the quartz. We have to decide in regard to included grains whether they are rich enough to go direct to, the furnace, or poor enough to throw away, or whether they lie between these two points and require recrushing as the only means of severing the values from the waste. This last case is the only one requiring special treatment at our hands. We will therefore consider that next. * By mutual consent, this paper has been presented also before the Colorado Scientific Society, and the Canadian Mining Institute, Montreal.

Feb 1, 1911

By H. S. Price, J. C. Cavendish, R. S. Varga

A numerical formulation of bigh-order accuracy, based on variational methods, is proposed for the solution of multidimensional diffusion-convection-type equations. Accurate solutions are obtained without the difficulties that standard finite difference approximations present. In addition, tests show that accurate solutions of a one-dimensional problem can be obtained in the neighborhood of a sharp front without the need for a large number of calculations for the entire region of interest. Results using these variational methods are compared with several standard finite difference approximations and with a technique based on the method of characteristics. The variational methods are shown to yield higher accuracies in less computer time. Finally, it is indicated how one can use these attractive features of the variational methods for solving miscible displacement problems in two dimensions. INTRODUCTION The problem of finding suitable numerical approximations for equations describing the transport of heat or mass by diffusion and convection simultaneously has been of interest for some time. Equations of this type, which will be called diffusionconvection equations, arise in describing many diverse physical processes. Of particular interest here is the equation describing the process by which one miscible liquid displaces another liquid in a one-dimensional porous medium. The behavior of such a system is described by the following parabolic partial differential equation:

Jan 1, 1969

By L. H. Simons, H. H. Spain

I NT RODUCTION Theory indicates that linear water-floods should exhibit scaling and stabilization properties in both oil-wet and water-wet porous media'. Experimental verification of these proper-ties in oil-wet media was obtained some time ago', and more recently, Perkins', employing a high permeability unconsoli dated sand and a low oil-to-water viscosity ratio, has obtained flooding data in a water-wet medium which follow the pattern of scaling and stabilization. Also, Root and Calhoun3 have found similar trends in the displacement of gas by liquids from unconsolidated sands. In general, however, the experimen-tal evidence appears still somewhat conflicting since scaling and stabilization of water floods in water-wet media has not been observed in most of the studies to date'.".'. The purpose of this paper is to provide a more comprehensive picture of waterflood behavior in water-wet media and to corroborate the validity of the scaling and stabiliza-tion concepts. The need for differentiating between the intrinsic nature of water-oil displacements inside a porous medium and perturbating secondary end effects is discussed, pertinent experimental procedures are outlined and the results of flooding tests conducted at low and at high oil-to-water viscosity ratios on con- solidated, water-wet Alundum cores are analyzed. END EFFECTS IN WATER-WET MEDIA Outlet End Effects The peculiar feature of the outlet end effect in water-wet cores is that it not only results in an excessive wetting phase saturation at the outflow face,'.' but that it also retards the moment of water breakthrough: i.e., causes an undue delay in the appearance of water in the produced effluent. Conditions existing in a water-wet core when water first arrives at the outflow face are schematically shown in Fig. 1. At this flooding stage the saturation distribution, Fig. la, has not yet been distorted by the outlet end effect. A water-invaded pore at the outlet core face, opening into the oil-filled void space between the end of the core and the end plate of the flooding cell, is illustrated in Fig. lb. The curvature of the water-oil interface is concave toward the outlet, and the pressure on the water side of the interface is lower than on the oil side by an amount equal to a certain capillary pressure (Fig. lc). Before the water (of this particular pore) can be produced from the core, it is apparent that the pressure in the water phase must exceed that in the oil outside the core. Accordingly. when water first reaches the outlet face, it will not leave the core but will accumulate inside, and only oil will be produced. Eventually, as the water injection is continued. sufficient pressure is built up in the water to reverse the curvature of the interfaces in the outlet pores, and only then will water be produced from the core. This stage, illustrated in Fig. 2. corresponds to the conventional "water breakthrough" observed in flooding experiments. For purposes of discussion, it is convenient to distinguish between the flooding stage at which water first arrives at the outlet face of a core (Fig. 1) and the stage at which water is first produced from the core ( Fig. 2). The former will be referred to as "water arrival" and the latter water breakthrough. In oil-wet media

By R. V. Norris

The great coal strike of 1902, which confined the work at the Short Mountain colliery of the Lykens Valley Coal Com pany almost exclusively to pumping, gave an opportunity to determine with considerable accuracy the cost of pumping the water from these very old, extensive and wet mines. This colliery, which is located in the extreme southwestern end of the anthracite coal-field, has been operated continuously since 1836, and has shipped 7,747,313 tons of coal. This and the Williamstown colliery are the only operations in Dauphin county. The workings cover about 5 miles along the North dip of the extreme westerly end of the basin, with the operating slopes near the center. They extend around the westerly spoon of the basin and back about 31/4 miles easterly on the South dip. The mines are very deep, the present workings ex tending to 711 ft. below sea-level, and about 1600 ft. below the lowest surface-opening. The coal is hoisted principally from the Short Mountain slope, which is 1550 ft. long, with 26 to 68 degrees dip, and from an inside slope, No. 4, 800 ft. long, with 52 to 72 degrees dip. The ordinary capacity of the colliery is about 1000 tons per day, and the average output for the years 1897 to 1901, in clusive, was 297,000 tons per year. The seams worked are the lowest Red Ash measures, being, respectively, Nos. I, II and III of the coal-bed series, but locally called the " Little Lykens," " Lykens," and " Whites." On the accompanying plan the Lykens seam is shown in full and the Whites in dotted lines. The pumping-plant is divided into four lifts, the pumps being located as shown in the section, Fig. 1, and the plan, Fig. 2.

Jan 1, 1904

By A. J. Terrones

THE classical papers on contact metasomatic deposits by Lindgren on the Clifton-Morenci district,' by Barrell on Marysville, Mont.,' and by Gold-schmitt on the Oslo district, Norway,' laid the foundation for understanding of the importance of separating the metamorphic process from the subsequent metasomatic stage. Knopf' made a big step forward by recognizing that sulfide ore minerals are invariably younger than silicates and by further stressing the importance of structural control" in ore finding. Some years later Harrison Schmitt" fought the idea that contact metasomatic deposits are erratic, irregular, bunchy, economically marginal, and of small size, concluding that these descriptions have little factual basis. He emphasized the importance of detail mapping and careful geological study as fundamental requirements for a better understanding of these deposits. This article presents a comparative description of the structural features at the Magistral, Antamina, Morococha, Vilca, Ferrobamba, Katanga (Quibio), Tintaya, and Huarca contact deposits (Fig. 1). Further, it will describe how these structural features controlled the emplacement of the intrusives, their shape, distribution of metamorphic and metasomatic halos, and sulfide deposition in post-skarn structural channelways. Finally, the modifications introduced by a superimposed hydrothermal stage recognized at some localities will be discussed. Primary exploration and careful sampling of recognized structural targets were instrumental in outlining the copper ore potential at the Antamina and Tintaya districts, thus proving the benefits and reward of careful geological examinations in this type of deposit. The Magistral District: This district lies in the Province of Pallasca, Department of Ancash, in northern Peru, at 8o 16' S and 77" 47' W. High to medium grade copper orebodies in garnetite, bordering a quartz monzonite stock, are exposed at the bottom of a glaciated valley in the western slope of the Andes at 4250 m (14,000 ft)* elevation.

Jan 1, 1959

By D. F. Malott

The Michigan Dept. of State Highways makes extensive use of geophysics for subsurface surveying which would be applicable for uses in other fields. Examples of resistivity surveys are given which include a proposed large-volume excavation with suggestions for land use after excavation, subsurface evaluation for engineering design, and a subsurface survey for land appraisal. An example of a combined refraction seismic and resistivity survey is shown where the resistivity is used for outlining the unconsolidated soils, while the seismic method is used to outline bedrock and to evaluate it for rippability. A refraction seismic survey at the bottom of bridge caissons for evaluation of bedrock uniformity and a rehtive aid in assessing rock strength is reported. These past several years have been a period of unprecendented construction and commercial expansion. Vast private manufacturing complexes and government road, power, and office projects are being built or are in planning stages. Nearly everywhere, municipalities are expanding outward and upward. Many towns are developing into cities and many cities are displaying new skylines, and the building boom shows little sign of slowing down.

Jan 1, 1970

CONTENTS PAGE ANDERSON, ARVID E., and CAMERON, FRANK K.-Recovery of Copper by Leaching, Ohio Copper Co. of Utah. Discussed by Thomas B. Brighton, H. C. Goodrich, Arvid E. Anderson, Thos. P. Billings, Frank K. Cameron 2 BEESON, J. J.-Mining Districts and Their Relation to Structural Geology. Discussed by Charles Keyes, Chas. A. Porter 4 DOBBEL, CHAS. A.-Deep-hole Prospecting at the Chief Consolidated Mines. Discussed by G. W. Crane 10 CRANE, G. W.-Notes on the Geology of East Tintic. Discussed by G. W. Crane, H. E. Havernor, N. O. Lawton 11 SACKETT, B. L., BARDWELL, CARLOS, JACOBSON, SIMON, and JENSEN, N. H. Lead Smelting in Utah. Discussed by D. W. Jessup, B. L. Sackett, E. H. Laws 13 BARDWELL, E. S., and MILLER, Roy H.-Pulverized Coal as Fuel for Copper Refining Furnaces. Discussed by L. D. Anderson, E. S. Bardwell, C. P. Crawford 15 WIGTON, G. H.-The Chief Consolidated Volatilization Process and Mill. Discussed by Thomas Varley, S. G. Olmstead, V. O. Lawton, O. C. Ralston.... 16 JESSUP, D. W.-Evolution in the Preparation of Ores for Lead Blast Furnaces. Discussed by W. Spencer Reid, D. W. Jessup, Carlos Bardwell 19 ALLEN, H. P., and MADGE, WM. C.-Chloridizing Mill of the Standard Reduction Co. Discussed by Thomas Varley, H. R. Hanley, H. P. Allen, George H. Dern 20 TUCKER, E. L., and HEAD, R. E.-Effect of Cyanogen Compounds on Floatability of Pure Sulfide Minerals. Discussed by Blarney Stevens 24 Mix, B. E., and BARKER, L. M.-Method of Unloading Ores and Coarse-crushing Practice at Magna Plant of Utah Copper Co. Discussed by W. C. Madge,B. E. Mix 25 KEIGLEY, C. T.-The New Byproduct Coke Plant of the Columbia Steel Corporation. Discussed by W. M. Grant, C. T. Keigley, A. C. Feilder 25 JACKSON, P. W.-Blast Furnace Plant of the Columbia Steel Corporation. Discussed by W. R. Phibbs, H. M. Henton 26 OLDRIGHT, G. L., KEYES, H. E., and WARTMAN, F. S.-Production of Ferric Sulfate and Sulfuric Acid from Roaster Gas. Discussed by G. D. Van Arsdale William E. Greenawalt, G. L. Oldright 27 MAZANY, M. S.-Braden Copper Company Caletones Smelter. Discussed by A. B. Young, G. L. Oldright 36 HARRINGTON, D.-Safety Methods in Utah Coal Mines. Discussed by Edward K. Judd, Otto Herres, Benedict Shubart, A. C. Watts, D. Harrington 36

Jan 12, 1925

By C. H. Wayman, D. W. Fuerstenau

The effect of bubble size and concentration of certain reagents on the terminal velocity, shape, path, and drag coefficients of single air bubbles in distilled water has been investigated. Bubbles of a certain size range rise considerably faster than Reynolds number-drag coefficient relationships predict, whereas a small amount of frothing agent reduces their terminal velocity. The rapid velocity at which bubbles rise in distilled water appears to result from slip at the boundary and from circulation within the bubbles. Surface-active agents retard bubble motion through prevention of both circulation and slip at the boundary. A surface tension concentration gradient helps maintain bubble sphericity. HE gas phase is one of the indispensible in-gredients in flotation operations. Flotation depends on the collision of an air bubble and a mineral particle in a pulp and their ability to remain in contact long enough for adherence to take place. Before it is possible to understand the mechanics of air bubble-mineral particle encounter, it is necessary to learn more about the nature of bubbles themselves before collision with a mineral particle has taken place. To date, little work has been done on air bubbles in flotation systems. In 1945 Fahren-wald' presented a study of the role of frothers on air bubbles and on aeration in flotation, and recently Wark and Sutherland' discussed the work of Rosenberg- in relation to flotation. The research reported in this present article was undertaken to investigate systematically the effect of bubble size and the concentration of certain reagents on the terminal velocity, shape, path, and drag coefficient of single bubbles in distilled water. Most of the work is concerned with the effect of a-terpineol on bubble motion in water, but studies were made with potassium chloride, potassium hydroxide, potassium ethyl xanthate, and potassium amyl xanthate. Experimental Method and Materials: To obtain free bubble rise and reduce wall and surface effects, the investigators used a tank of 5½x5½x30-in. internal dimensions, filled with water to within 4 % in. of the top.' The tank was made of acrylic plastic so that the walls would have good optical properties. Distilled water, which was re-distilled in a block tin still and saturated with air before each test, was used in all the experiments. All solutions were made with reagent-grade chemicals. During each experiment the water was at room temperature, and during the course of an experiment the temperature did not fluctuate more than 0.5°C. Since the experiments were performed over a period of six months, the temperature varied between 25° and 27°C. The temperature at which each series of experiments was conducted is recorded with the data. The experimental apparatus is presented dia-grammatically in Fig. l. Individual air bubbles were generated from purified compressed air through a capillary of 0.003-cm internal diameter at a rate

Jan 1, 1959

By Christopher Haycocks, Lawrence P. Johnson, George M. Neall, James M. Townsend

No method of roof control yet devised has proven to be universally acceptable for the wide range of strata conditions experienced in U. S. coal mines. However, a relatively new innovation, the roof truss, has proven itself capable of preventing roof failures which both conventional and resin bolting could not. Presently, the economics of roof trusses are not favorable when compared to bolting due primarily to drilling and installation procedures, but this is expected to change with improved truss and equipment designs. To realize the full potential of this new method of roof control, design criteria are needed which can optimize the effect of the truss for varying strata conditions. A review of the literature reveals that some work has been conducted on the roof truss. Cambrell and Haynes1 (1970) showed that the roof truss is superior to angled roofbolts installed through a header. Sheorey, Verma, and Singh2 (1973) used statics to prove that the optimum angle of inclination should be greater than 45°. However, to date, no systematic attempt has been made to establish design criteria. In this paper, the problem was approached in three ways. First, model studies were performed to determine general trends of truss support as a function of a number of variables. This provided a better understanding of the support mechanism involved. Secondly, beam theory was employed to calculate the actual support capacity of a truss, realizing the many simplifications, assumptions, and shortcomings of this approach to such a complicated problem. Last, field testing will be utilized to test the hypotheses previously developed and provide hard data to further synthesize roof truss design criteria. Field testing has recently commenced and should be complete before mid 1977.

Jan 1, 1979

By W. E. Wrather

CURTAILMENT of production was a matter of far more serious concern to the oil industry through 1933 than the search for new supplies of oil. The huge reserves of crude, built up during past years, instead of inspiring a feeling of security, were viewed apprehensively. The status of past laws and court decisions seemed to guarantee to operators the right to produce oil at will, and this entrenched privilege was so widely adhered to that the market was-in a constant state of chaos. The more modern idea of the ownership of oil in place and correlative rights gained headway slowly, since usually there were enough belligerent producers, staunch believers in the old established order, to defeat the efforts of the majority who sought to' introduce order and restraint. State regulatory commissions were unable to cope, with the rebellion among producers with the result that those who abided by proration rulings were penalized, while those who flouted the rulings and produced unrestrainedly were able to make profits on large volumes of flush oil even at low prices. This situation, known in the vernacular as the "hot 'oil" problem, became so acute that the industry was threatened with ruin. The low price for 36c A.P.I. in the Mid-Continent came in April. at 25c per barrel 'but gradually moved upward to the long-hoped for price of $1.00 per barrel in October, after the Federal Government had taken a hand in the matter and effectively allocated production among the oil producing states and materially curbed the "hot oil" runs.

Jan 1, 1934

By Thomas T., Read

IT does not seem practicable to review all the other specialized curricula that have developed in the mineral industries field in so much detail as has been given for petroleum. Nor is it easy to draw a definite line between true curricula, leading to a designated degree in the special subject, and options, which may range from the mere substitution of one or two courses for others ' in the final years to differences so extensive as almost to amount to separate curricula. Even to attempt to catalogue all the options that have been offered at one time or another would , require too much space. The remainder of this discussion, there- fore, will be confined to three topics which seem to be of major importance. Mining and metallurgical curricula will be covered in a later chapter. Geology The first, from the historical view, is geology in its relation to the mineral industries. Previous, chapters have made clear that in the early years of mineral industry instruction in the United States economic geology and mining engineering, so overlapped one another that men who were by training and experience economic geologists were appointed professors of mining, while men who had graduated as mining engineers sometimes developed into professors of geology. Even today men whose basic training was in- geology as a pure science, and who perhaps took a doctor's .degree in that subject, have attained such distinction in the mineral industries as to be universally accepted as "mining men," and their right to be regarded as mining engineers would not be questioned, even though 'they did not .take a degree in engineering. Nevertheless the distinction does exist, and has been made a concrete reality in recent years by the enactment of

Jan 1, 1941

By Norman F. Schulz

The technical excellence of separation achieved in a mineral concentration process, or any other process where two constituents of any kind are physically separated from each other, is expressed uniquely and quantitatively by the separation efficiency (E,): E. = (R - R,), where R is the percentage of the valuable constituent and R, the percentage of the waste appearing in the concentrate. The separation efficiency meets all the usual requirements of a true efficiency and is independent of the nature of the process used. It can be visualized as the percentage of the feed material that, in effect, actually undergoes complete separation while the rest of the feed is distributed randomly and unchanged into the two separation products. The problem of quantitatively assessing the results of a mineral concentration process recurs whenever one tries to decide which of two similar test results is more desirable. Although economic factors may greatly influence the eventual choice of process, they usually have very little to do with the technical excellence of a separation and are, therefore, not a consideration at this point. Concentrate grade and recovery, used simultaneously are the most widely accepted measures of performance, and if both the grade and the recovery are greater for one case than for another, the choice is simple. However, when the results of closely competitive operations are compared, it often occurs that one set of test results shows a higher grade and a lower recovery than another and the choice is no longer obvious. Laboratory investigations of a mineral concentration process applied to a given feed material can often be designed to yield successive paired values of concentrate grade and recovery over the practical range of the course of a separation process.' These results may be plotted as some combination of the cumulative values of grade, weight recovery, or unit recovery in the concentrate. The resulting correlations for two slightly different sets of conditions can then be compared qualitatively, or even quantitatively in particular cases.2 Such comparisons are not applicable, however, to individual concentration test results. The reduction of a separation test result to a single efficiency figure, preferably as a percentage of ideality, would afford the simplest and most precise means for comparing the results of competitive tests. The effective proportion of feed material that undergoes complete separation in any real concentration process, hereafter referred to as "separation efficiency," is such a figure. It is essily calculated from the usual feed and product data and can even be evaluated, in many cases, from data in publications describing various concentration processes. Mineral Concentration Processes and Their Evaluation Mineral Concentration Processes: The overall concentration process may be subdivided into a liberation process which severs the bonds between unlike mineral species, and a separation process, which sorts the resulting liberated particles into two products—a concentrate rich in mineral A and a tailing lean in mineral A. A perfect mineral concentration process is represented by the idealized scheme shown in Fig. 1 in which liberation and separation are not differentiated. The feed mixture consists of two mineral types which are completely liberated early in the process and then sorted by type. All the mineral particles of type A which respond uniquely to the selection forces acting in the ideal separator, report to the concentrate, while all the mineral particles of type non-A report to the tail-

Jan 1, 1971

Albin. B . R Billings. Mont . '28 Amnter . Nathan L 26 Broad St.. New York . N . Y . '28 Bache . Jules S 42 Broadway. New York. N . Y . '28 Borrett . C . P . 5338 Harper Ave .. Chicago. I11 '28 Baum . Frank G. . Cons . Hydro-Electric Engr Camel'. Shasta Co. . Cal. '23 Baylean, William S Russ Bldg .. San Francisco. Cal . '28 Bean, Louis H .. V.P.. Dwight P . Robinson & Co.. lnc 126 E . 46th St New York. N . Y . '28 Beatty . Roes J . 1106 First National Bank' Bldg .. Chicago . Ill . '28 Benwell . Oswald F . 110 Gilpin St .. Denver. 1310 . '28 Beymer. Albert 9.. V.P .. Keystone. National Bank Pittsburgh. Pa . '28

Jan 1, 1929