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By Eric J. Jette

In thermodynamic studies of gas mixtures and liquid solutions, the respective problems have been greatly simplified by the use of two general limiting laws; Dalton's law of partial pressures and Raoult's law. It is generally recognized that these two laws have a common physical and chemical basis which may be stated as follows: The law may be expected to be strictly valid only for systems in which the different molecular species are so nearly the same in their physical and chemical properties that a molecule is unable to recognize whether its neighbor is one of its own kind or not. Positive and negative deviations from both laws are frequently encountered. The occurrence of negative deviations in both gases and liquids is ascribed to attractive forces which, in the more extreme cases, may be so large in magnitude and so highly specific in character as to lead to the formation of definite chemical compounds. Positive deviations in gases develop only at higher pressures where the intermolecular distances are so decreased that factors such as molecular size and shape, which ultimately become concerned with the repulsive forces, come into play. In liquid mixtures, positive deviations are generally considered as due to differences in the symmetrical (nonpolar) fields of force which surround the various molecular species and which are supposed to give rise to a tendency for each species to associate with its own kind and thus to "squeeze out" the other variety. Fundamentally this also involves the existence of repulsive forces between unlike molecules. If the fields of force are unsymmetrical (polar) a tendency towards compound formation results. Stated in more exact terms, strict adherence to the law means that the "activity" (or any adequate measure of this quantity) of a component in a mixture is a linear function of the molecular (or atomic) fraction of that component between the mol fraction limits 0 and 1. A positive deviation means that the activity is greater than corresponds to the law; a negative deviation that the activity is less. The deviations from Raoult's law have been fully discussed by many writers1

Jan 1, 1934

By Bruce F. Grant, Stefan F. Szasz

During 1947, a Sinclair research team was assigned to investigate thermal methods of oil recovery. The assignment was recommended by a survey of possible research approaches to increase the amount of oil that ultimately can be recovered from oil producing reservoirs. The use of heat to stimulate oil production rates by the melting of paraffin deposited in well bores can be traced back to within one or two decades of the drilling of the Drake well. The application of heat on a larger scale has been discussed by generations of oil producers. Shortly after the turn of the century, one intrepid operator is reported to have injected steam into a Pennsylvania property. After a few weeks, he apparently became discouraged and terminated his experiment. Subsequently, the literature contains references to several well-developed techniques for supplying heat to a producing well bore to melt paraffin or to reduce the viscosity of oil contained in the formation immediately around the well bore.1.?.3.4 Some early references discuss procedures to furnish heat to the reservoir,5,6 with the injection well as the heat source, thus obligating the process to maintain the entire rock mass at a temperature above that at which the desired improvement in oil recovery would occur. Another approach to reservoir heating was reported by a group of Russian technologists in 1935.7,8,9 They definitely demonstrated that combustion can occur within the porous structure of an oil-bearing sandstone. Their field experiments, however, relied less on combustion within the rock than on heat furnished by combustion of oil supplied to the injection well bore. Ignition of the air-oil mixtures in the well bore was found very difficult, and the field tests were carried on for only short periods of time. Publication of the Russian work spurred at least one independent operator in this country to try firing an air-gas injection well, on for only short periods of time. Publication of the Russian work spurred at least one independent operator in this country to try firing an air-gas injection well. The Brundred Oil Corp. reportedly obtained combustion in the sand immediately around the injection well bore, but the experiment was abandoned because of interference with normal production schedules. Injection capacity of the experimental well was greatly reduced by firing. The well was reshot and pieces of sand showing partial fusing of the quartz matrix were recovered. To the authors' knowledge no other field experiments utilizing combustion techniques for formation heating were undertaken prior to 1948, although the patent literature evidences continued interest in formation heating."'," CONCEPT OF COMBUSTION-SUPPORTED HEAT WAVE The references cited were in agreement that heat applied to a reservoir would increase recovery, but there

Jan 1, 1955

By Joseph E. Pogue

Proration in the petroleum industry has come to mean a method for curtailing the production of crude petroleum by artificial effort, and it is in this sense that the term is employed throughout this paper. Although a contrived curb on supply has been invoked at various times in the past in particular fields and to meet specific situations, it is not until the past few years that this procedure has become general and assumed a dominant role in the oil business. In the sense that we now understand it, proration had its inception in the Seminole area of Oklahoma in 1927, from which time and place the practice spread to include practically all the flush oil fields of the country, especially those of California, Kansas, Oklahoma and Texas. At present there is perhaps no phase of the oil business that commands more attention than proration, nor one that engages more time and effort on the part of executives in the business. The practice of proration, indeed, has not only become an integral part of the policy of most companies and operators, but it has also taken on the aspects of a "movement" involving two schools of thought with considerable feeling, and at times some bitterness, on both sides. In this atmosphere it is difficult to find calm, dispassionate consideration of proration, for most discussions are either vigorous exhortations by its proponents, or else sharp condemnations by its opponents; although it appears that the majority of the industry is clearly "in favor of" proration. It is hoped that this analysis will be taken as an attempt to appraise the movement as an economic force, without bias and without regard to the incidence of the conclusions upon any preconceptions that the industry may entertain. Evolution of Proration To appreciate the causes that brought proration into being, it is necessary to view briefly the development of the petroleum industry over the past twenty years, approximately the span of the gasoline era., For the first ten years of the period, the industry was seeking capital

Jan 1, 1932

By R. B. Gordon, D. A. Koss

Ultrasonic-atlenuation changes due to the formation of free dislocations have been observed during tensile tests of magnesium and LiF single crystals and samples of polycrystalline Results on the LiF and samples are similar: A preyield attenzration increase is observed which, however, be-corlzes smaller as the magnitude of the drop in load al yielding increases. This indicates that the yield point observed in these materials is due to dislovation rather than dislocation unpinning and that the initial density ' free dislocations must be low if the yield point is to be sharp,. Tests on the magnesium ere conducted at both 27" and 200C. Magnesium has the unusual property that the yield drop is larger at the higher test temperature and is accomplished by a decrease in attenuation. The latter is due principally to the temprovary pinning of detained dislocations by highly solute atoms. After strain aging., a stress as low as 0.3 bur suffices to unpin dislocations; microstrain measuements of sufficient sensitivity should. reveal plastic flow at stress levels this low IN another paper,' we describe the technique of simultaneously observing ultrasonic-attenuation changes and plastic microstrain during deformation of spher-oidized carbon steels. Changes of ultrasonic attenuation indicate damping effects caused by the oscillation of long, freely moving dislocation segments. Simultaneous microstrain measurements are used to indicate total dislocation motion. The dislocation-damping observations are most useful in the study of the early stages of deformation where the dislocation density is low and the plastic strain is small and relatively difficult to measure. Particularly interesting results are found in materials which display sharp yield points. Observations of these phenomena are reported here for three materials: single-crystal LiF and magnesium, and poly crystalline molybdenum. EXPERIMENTS Dislocation-damping effects were observed by measuring changes in acoustic attenuation with the ultrasonic-pulse method. The end faces of each of the specimens were ground flat and parallel and a quartz 10 Mc per sec, x-cut transducer was attached to one face. The bonding agents used were: a) "Nonaq" stopcock grease with magnesium, b) beeswax with LiF, and c) salol with molybdenum. With the LiF, the best acoustic signals were obtained at 45 and 50 Mc per sec; all other measurements reported are at 10 MC per sec. The Sperry Ultrasonic Attenuation Comparator2 was used to measure attenuation changes. In the

Jan 1, 1967

By Orville R. Lyons, A. C. Richardson

During the past few years there has been a growing demand by coal operators for detailed information about the performance characteristics of the various dryers now being manufactured, preferably in such a form that the information could be used to determine the type of dryer best suited to a particular drying problem. A few operators have been desirous of going even further, because they are of the opinion that present-day dryers are not properly designed and that fundamental studies of dryer design should be undertaken. This growing demand for a method of dryer evaluation and the indicated need for fundamental research resulted in the sponsorship by Bituminous Coal Research, Inc. of a project at Battelle Memorial Institute to investigate the thermal drying of coal. In investigating this problem, the most feasible method of attack appeared to be a survey of active operations to determine the present status of the thermal drying of coal. Data were obtained, usually by actual plant tests with the cooperation of the various preparation engineers and their staffs, for 9 screen-type dryers, 8 rotary-type dryers, 3 continuous-pallet-type dryers, 2 flash-type dryers, I tray-type dryer, and I cascade-type dryer. The testing program provided: (I) data for 24 coal-drying operations, (2) information about the inherent characteristics of the coals dried, (3) information about the previous treatment that the coal had received, and (4) information about operating costs. The data obtained through the dryer survey and relationships determined from the data make it evident that all of the types of dryers included in the survey can be operated with the same degree of effectiveness if each type of dryer is used to dry the sizes of coal for which it is best suited. It should be noted that it is usually undesirable and often impossible to dry different sizes of coal in one type of dryer. By use of the data in the report, any prospective dryer user, having determined the surface moisture percentage and screen-size analysis of the coal to be dried, the tons of water to be removed per hour, and the final surface moisture percentage desired, should be able to determine with a fair degree of accuracy: (I) the difficulty of the drying problem, (2) the approximate cost of drying, (3) the required dryer inlet gas temperature and volume and exhaust gas temperature and volume, (4) the type of dryer to use, and (5) the size of dryer required. The method of testing the dryers and determining the difficulty of drying can be used by operators already having dryers to check the performance of their particular dryer and determine whether they are operating effectively. Considerably more information was obtained from the survey of thermal drying than was anticipated when the survey was first considered. However, a great deal of work still remains to be done in the field

Jan 1, 1949

By C. W. Gibbs, E. K. Parks

In 1929 the Standard Oil Company of California commenced the development of a device for obtaining temperatures and pressures in flowing and shut-in wells and of suitable running equipment for such a recorder. Although simple in principle, the recorder has required much experimental work in its development. The various problems have now been solved to such an extent that it is believed that the apparatus affords a sturdy and reliable means for obtaining information regarding depth pressures,—apparatus that may be turned over to a well gang for routine operation. As an example of the rough usage the device will withstand a recent incident may be cited. Owing to failure of the lowering line at the conclusion of a run a recorder was dropped some 6300 ft. through 2 1/2-in. tubing filled with gassy oil. The device was fished out undamaged and with the pressure record intact, although the instrument had been subjected to a pressure greater than 2300 lb. per sq. in. for some 24 hr. after impact at bottom. Description of Recorder The instrument is of the continuous recording loaded spring type (Fig. I). Temperature is not recorded continuously but is obtained by maximum recording thermometers in an auxiliary thermometer well. The entire instrument assembly, from bottom of the recorder to top of the socket, is 6 1/2 ft. long and weighs less than 25 lb. The maximum outside diameter of the recorder shell is 1 1/4in., and all attachments need be no larger. This permits lowering the device inside 2-in. tubing. The operating principle is simple. The well pressure acts upon a piston A resisted by the extension of spring B. The spring deflection is recorded by a stylus C upon paper within the recording drum D. Springs.—To improve accuracy at lower maximum well pressures five interchangeable spring assemblies are used. These have maximum pressure ranges of from 250 to 5000 lb. per sq. in. Piston diameter is the same in all cases, and each spring is designed for a deflection of about 5 in. for maximum pressure loading. A complete spring assembly there-

Jan 1, 1934

By Hugh Douglas

ANTIMONY Antimony (Sb) has been used since the early Egyptian dynasties. Prior to World War I, total demand amounted to only 6000 to 7000 tons per year (tpy). Wartime uses and rapid rise of industrialization in the Northern Hemisphere nations have pushed world antimony use to the 78,000-tpy level. An overwhelming supply of low-cost antimonial resources in the Sino-Russian bloc countries has and will continue to have a major impact on availability and price to users outside the bloc. Table 14.4.1 shows trends in world production, United States production and consumption, and prices. Demand Antimony is used principally as an alloy in lead-based metals and other alloys. Pure metallic antimony usage is small and is confined to such areas as laboratory and electronic applications. Lead-antimony alloys are used in automobile storage batteries, chemical pumps, and pipes, tank linings, roofing material, and cable sheaths. The metal increases the hardness of lead, and, for such uses as foundry printing type, reduces shrinkage for casting and lowers the melting point. Antimonial oxides are used for ceramic purposes, white paint pigments, glass forming, textile finishing, fire retardants in military clothing, matches, and solder. Wartime applications include use as hardener for bullets, an element for tracer bullets, and ingredient for producing dense white smoke for visual markers. A small but rapidly growing use for antimony is for metallic compounds in semiconductors and thermoelectric devices. In the United States demand for antimony is about evenly divided between metallic end-use markets and nonmetallic markets. In metallic end uses, antimonial lead accounts for 27% of total metallic and nonmetallic use; in nonmetallic areas major uses are flame retardants (15%) which is the fastest growing market, plastics (13 % ), and ceramics and glass (11%). While antimony has advantages in most of its applications, there are uses in which other materials can be substituted, including: mercury, titanium, lead, zinc, chromium, tin, and zirconium in paints and pigments; tin in sheathings; calcium in battery plates; and bismuth in type metal. Supply Antimony is produced from both antimony ores and as a byproduct of smelting other ores. The principal ore mineral is stibnite (Sb2S3), along with its oxidized antimonial minerals and derivatives which occur in small discontinuous replacement veins or fissure vein implacements. Stibnite occurs in quartz-gold veins and copper-lead-zinc

Jan 1, 1976

By H. A. Baumann

Experimental data are presented showing the influence of size consist and firing rate upon the performance of bituminous coal-fired, single-retort, industrial underfeed stokers. Size segregation, degradation, and distributor data are also included. The conclusion is reached that size consist of the fuel as fired, is a critical factor in its performance on this class of equipment.

Jan 1, 1950

By Walter E. Duncan, Oscar F. Tangel, A. M. Gaudin, Franklin Dewey, R. A. Johnson

Xanthates have been used as collectors of sulfide minerals in the concentration of ores by flotation for over a decade, yet much remains to be done to elucidate the underlying reasons for the remarkable effectiveness of these compounds in this connection. Briefly stated, the known facts concerning the effect of these reagents on the floatability of minerals are as follows: 1. Xanthates are without effect on silicates, silica, and generally on minerals currently regarded as "gangues." 2. Xanthates in very small amount increase enormously the floatability of sulfides of copper, lead, silver, iron and mercury. 3. If zinc sulfides are first '(activated," as by treatment with a copper salt, they are readily floated by xanthates; otherwise not. 4. Elemental copper, silver and gold have their floatabilities increased by xanthates. 5. Sulfides of elements that are not typically metallic—e.g., stibnite, realgar, molybdenit—are not made to float markedly better by treatment with xanthates. 6. Oxidized minerals of lead and copper are floated if treated with large amounts of xanthates, but not so if treated with amounts of the same order of magnitude as required for sulfide flotation. Oxidized zinc minerals are not floated unless xanthates having unusually long hydrocarbon chains (e.g., eight carbon atoms or more) are used. Iron oxides and carbonate are not floated by xanthates. From a flotation standpoint the most striking feature about xanthates is the very small amount required to accomplish startling changes in the behavior of some minerals. The amounts used in practice to effect excellent concentration are frequently of the order of 0.05 lb, of agent per ton of ore; that is, of the order of one part of agent per forty thousand parts of ore. Changes in amount of agent of the order of 0.01 lb. per ton of ore (or 0.002 lb. per ton of pulp, on a 4:l basis) have marked effects on the metallurgical results obtained. Yet these changes represent a variation of but one part per million parts of pulp.

Jan 1, 1935

By C. A. Hansen

Page Introduction............................206 Power Characteristics in Zinc Sulfate Electrolysis........... 207 Current Efficiency......................... 207 Corrosion Rates..........................216 Voltage Required by the Zinc Cell..................219 Power Requirements of the Zinc Cell ................221 Impurities in Zinc Electrolyte.....................222 Non-cumulative Impurities.....................223 Cumulative Impurities ....................226 Impurities in General........................228 Temperature and the Stability of the Zinc Cell..............229 Practical Expedients for Control of the Zinc Cell...........234 Acknowledgments...........................234 Appendix................................235 Discussion...................:.......... - 236 Introduction It has been the experience of the writer, during some five years' work with electrolytic zinc, that the zinc cell is perhaps more sensitive to impurities in the electrolyte than the analytical methods as yet developed for the chemical identification and determination of these impurities; but that, when proper purification methods have been applied to a given solution, the behavior of the cell is quite independent of the original sources from which the zinc sulfate has been derived. It has also appeared that the behavior of the zinc cell is the best and surest check on the correctness and thoroughness of the purification methods used, because it indicates the presence of both current impurities and cumulative impurities derived from the leaching of the ore; it also indicates whether these impurities are current or cumulative, at least in so far as they are of serious importance commercially.

Jan 1, 1919

By K. C. Ko, M. K. McCarter

Experimentation with seismic velocity measurements at Kennecott Copper Corp.'s Bingham mine disclosed that some recognized slide areas are characterized by low velocity profiles. A new traverse technique employed during the investigation allows rapid and precise measurements of a quantity referred to as "apparent velocity." This value is a weighted average of the actual velocity in the overbreak zone near the surface and in the intact rock at depth. The low points on the velocity profile are apparently the result of lower actual velocities and deeper overbreak in less competent material within the slide zones. Experience verifies the usefulness and practicality of the technique in delineating adverse areas prior to detectable failure. The technique may be employed as a rapid and economic means of slope stability surveillance in large open pit mines.

Jan 1, 1973

By C. E. Sims, C. A. Zapffe

MANY hundreds of publications have appeared during the past 78 years that treat the subject of hydrogen in iron and steel,105 but conclusions regarding the functions of hydrogen in causing some important defects in steel are still unsatisfactory to many; and other hydrogen-caused phenomena yet remain to be identified with this gas. The most widely discussed of these defects is hydrogen embrittlement, but the conception, perhaps the popular one, that embrittlement is due to hydride formation does not conform to the known facts.104 The true identity of hydrogen embrittlement seems instead to lie in a mosaic nature of metal crystals, which is a concept not yet accepted by most metallurgists. A study of hydrogen embrittlement therefore provides new viewpoints in regard to the crystalline substructure of steel. A second widely discussed hydrogen-caused defect is the "flake" or "shatter crack." Although it is generally agreed that the presence of hydrogen is a prerequisite for their appearance, it is also realized that internal stress plays a decisive part. The relationship of hydrogen to internal stress has not been explained very clearly; nor is it always clear what the relationship is between a "flake" and a "snowflake," or between a "fish eye" and a "shatter crack." More importantly, the relationships among hydrogen embrittlement, hydrogen-caused fissures such as "flakes" and the ultramicroscopic structure of steel have scarcely been recognized. The present investigation attempts to provide an explanation for the embrittlement of steel by hydrogen by showing cause for accepting the "block" concept of metal crystals, and then to show how the numerous hydrogen-caused defects are interrelated in the light of this concept. EVIDENCE OF SUBSTRUCTURE IN METAL CRYSTALS It appears that the concept of a crystal as an aggregate of smaller multi-atom units must be accepted in some form if the behavior of metals is to be understood. The abundant literature on the evidence of an ultramicroscopic "mosaic" structure in metals and other crystalline substances suggests that the physicist has provided the metallurgist with an invaluable new insight. The exact picturization that any one physicist provides may be open to question, but the fact that there is some such fundamental substructure seems undeniable. The present work makes no pretense of comprehensively treating the imperfection structure theories. Nor will conclusions be drawn here regarding the exact nature of the substructure of crystals. However, the acceptance of some imperfection theory of fundamental attributes seems so necessary to an understanding of the behavior of hydrogen in steel that the following brief

Jan 1, 1941

By Walter M. Stephen

Modern developments in alloy steels have been so rapid and diverse that engineering practice has scarcely had time to re-appraise all items of past experience wherein conclusions became axiomatic under conditions that no longer apply. A case in point is the wet screening of abrasive ores within the fine range still looked upon as belonging exclusively to classifiers. By virtue of the development of stainless steels (18 per cent Cr, 8 per cent Ni), it is no longer true that classifiers are more economical than screens in closed circuit with large-tonnage ball or rod mills at 65 or even 100 mesh, provided a selective overgrind of the higher-gravity constituents of the ore is not desired. Wet screening of ores is a highly corrosive as well as an abrasive operation, because of the inevitably high degree of oxygenation of the water. Screen cloth of ordinary or spring-steel wire almost at once becomes pitted and covered with a film of corrosion products, which causes rust-blinding of fine-mesh screens and offers high frictional impedance to the flow of ore particles. On the other hand, the well-known properties of stainless steel enable it to maintain a bright surface, and so to eliminate blinding either by ore particles or by corrosion products. That a large-tonnage mill grinding hard ore to 65 mesh can be operated economically in closed circuit with screens instead of classifiers has recently been demonstrated at the Copper Cliff concentrator of the International Nickel Co.; in the test to be described, a 6½ by 12½-ft. Marcy rod mill ground from 625 to 820 tons of ore per day to approximately 65 mesh, operating in closed circuit with three 4 by 5-ft. Hum-mer screens, without any classifier. Stainless-steel cloth gave an indicated life of several months. There was no difficulty with blinding, yet dilution and spray water could be controlled so that screen undersize averaged not less than 40 per cent solids. In contrast, ordinary carbon steel was pitted and blind with rust within 40 hours.

Jan 1, 1939

By Walter M. Stephen

Modern developments in alloy steels have been so rapid and diverse that engineering practice has scarcely had time to re-appraise all items of past experience wherein conclusions became axiomatic under conditions that no longer apply. A case in point is the wet screening of abrasive ores within the fine range still looked upon as belonging exclusively to classifiers. By virtue of the development of stainless steels (18 per cent Cr, 8 per cent Ni), it is no longer true that classifiers are more economical than screens in closed circuit with large-tonnage ball or rod mills at 65 or even 100 mesh, provided a selective overgrind of the higher-gravity constituents of the ore is not desired. Wet screening of ores is a highly corrosive as well as an abrasive operation, because of the inevitably high degree of oxygenation of the water. Screen cloth of ordinary or spring-steel wire almost at once becomes pitted and covered with a film of corrosion products, which causes rust-blinding of fine-mesh screens and offers high frictional impedance to the flow of ore particles. On the other hand, the well-known properties of stainless steel enable it to maintain a bright surface, and so to eliminate blinding either by ore particles or by corrosion products. That a large-tonnage mill grinding hard ore to 65 mesh can be operated economically in closed circuit with screens instead of classifiers has recently been demonstrated at the Copper Cliff concentrator of the International Nickel Co.; in the test to be described, a 6½ by 12½-ft. Marcy rod mill ground from 625 to 820 tons of ore per day to approximately 65 mesh, operating in closed circuit with three 4 by 5-ft. Hum-mer screens, without any classifier. Stainless-steel cloth gave an indicated life of several months. There was no difficulty with blinding, yet dilution and spray water could be controlled so that screen undersize averaged not less than 40 per cent solids. In contrast, ordinary carbon steel was pitted and blind with rust within 40 hours.

Jan 1, 1939

By Herbert A. Wendel

Reaching the miner with safety education" is R the ultimate goal, the main objective, of every safety program in the mining industry. If we can get safety education to every worker, and it is properly learned, enforced and obeyed, we should eliminate at least 85% of all potential accidents. We should then have very few accidents as a result of unsafe behavior, which, in turn, would allow us to concentrate most of our future efforts on preventing the types of accidents which are caused by faulty or defective machinery, equipment, tools and materials. An uninformed or uninitiated person would think that it should be a rather simple process to reach the miner with a safety education. Theoretically he would be right because here we get involved in a matter of semantics. When we say "reaching the miner with safety education" we actually mean that this education must also be accepted and learned by the miner; we intend to mean that safety must be observed and followed at all times. But in order to realize our complete meaning of the phrase, we must find the solution for a number of problems and obstacles which are well known to management and safety personnel.

Jan 1, 1965

By Howard Thompson, H. N. Hall, Frank Nuss

Removal of bit cuttings is an important function of drilling muds. In an effort to obtain better understanding of the factors influencing the removal of cuttings, an extensive series of laboratory tests were made in which slip velocities of various sizes and shapes of particles were measured in muds of different physical properties. Empirical equations were then derived from these experimental data. These equations show that slip velocity is dependent on cutting size and shape, mud flow constants, and flow state of the mud. Applicability of these equations for field use is demonstrated by comparing computed slip velocities with slip velocities obtained from field tests. Drilling muds have many functions, but perhaps the most important is the removal of bit cuttings from the well. In a 10,000-ft well, the weight of rock which is drilled and must be carried to the surface is over 150 tons. In addition to this, the mud must remove any sloughings from the well bore. Failure of the mud to promptly remove either bit cuttings or sloughs from the well bore causes re-drilling and excessive wear on bit teeth, slows down drilling rate thereby increasing well costs, and greatly increases possibilities for stuck drill pipe when circulation is stopped for any length of time. Drilling muds lift bit cuttings to the surface by means of the upward velocity of the drilling mud in the annulus. Because a density difference exists between the rock being drilled and the drilling mud, there is a difference between mud velocity and the rate of bit cutting travel, called the net rise velocity. To evaluate the ability of any type of drilling mud in respect to lifting cuttings, some method must be known for predicting the rate of fall of cuttings through mud traveling upwards in the annulus. Equations for the rate of fall of particles through a true fluid have been satisfactorily determined by several authors. 1-6 Since drilling muds are not true fluids, but obey the laws of Bing-ham,7 it should not be expected that equations for rate of fall of cuttings in a true fluid would be applicable to plastic fluids such as drilling muds. Several authors have attempted to compute cutting slip velocities in muds using a viscosity value obtained with a Stormer viscosimeter; however, unsatisfactory results were obtained. Pigott8 took cognizance of the phenomenon of variation of viscosity with velocity in laminar Row, and calculated laminar slip velocities using a variable viscosity with Stokes law, and turbulent slip velocities using Rittingers law. Drilling muds obey the laws of plastic flow which involve factors not affect-

Jan 1, 1950

By Oliver C. Ralston, Foster Fraas

VIRTUALLY all commercial use of electrostatic separation has employed separators depending on differences of conductance of the broken, solid mixtures treated by them. The two main types of conductance separators have been: (1) Those in which the separating field is as near a static field between two charged electrodes as it is possible to maintain in the face of the usual leakage that takes place between electrodes with some 5 to 50 kv tension between them and spacing of l/z to 3 in.; (2) those in which a convective discharge of corona or spray type, but not a spark discharge, takes place between the carrier electrode and a charged electrode facing it, which is of very restricted area, such as a row of needle points or a small diameter wire parallel to the face of the carrier electrode. The present paper deals with this latter type. The principle is usable in separators where the carrier electrode, usually grounded, has the shape of a roller, a conveyor belt, a vibrating table, a sloping chute, or a nearly vertical plate. The innovation studied by us has been the use of the convective field for charging material on the carrier electrode and succeeded by a field between the carrier electrode and an electrode made of a true dielectric which cannot take on a charge by conduction but is charged by being in the radius of the corona discharge. The acquired charge is of the same sign as that of the corona but is not dischargable by contact with a good conductor. However, high-tension charge tends to leak off because of the ionization of the ambient air. The field between this electrode and the carrier electrode is as near static as it is possible to obtain. There are some differences in behavior of this electrode and that of the gas tube electrode used by Sutton, as will be discussed below. Both electrodes cause increased adhesion of nonconductive particles to the carrier roll. The particles are pinned there because they are convectively charged on their outer surfaces facing the corona electrode. The electrodes also cause increased rate of release of conductive particles tending to be pinned by corona charging but conveying the charge to the grounded carrier roll almost as rapidly as it is received by the particles.

Jan 10, 1950

By William Newnam

WHEN Hugh Lee Pattinson discovered, in 1829, that the crystals formed during the slow cooling of molten lead were poorer, and the remaining liquid richer in silver, than the original lead, an important step was made in the metallurgy of this metal. Being the first process applicable to the desilverization of low-grade lead bullion, it soon found its way into all European countries having such a product to treat, thereby effecting the saving of many ounces of silver annually which previously had been thrown away. The old hand process was expensive, as viewed from the standpoint of more modern methods; the labor was great anti the tonnage was small, but on the other hand the results were fairly, satisfactory. This process flourished for some time after the introduction of the cheaper Parkes process in 1852 and it is still in use in a few European smelteries. Only one notable improvement was made on the original process, that of Luce and Roan at Marseilles, France. It consisted in the application of steam for stirring and the tapping of one-third of the liquid lead, through perforated plates covering the tap holes flush with the bottom of the kettle, thus leaving two-thirds in the form of crystals in the original kettle. This modification considerably lowered the operating costs as it permitted of much larger kettles, an increased tonnage and eliminated much of the slow, hard labor of the hand process.. The Luce and Rozan process has persisted in its original form to the present clay. Stephen Tredinnick, English born, spent most of his years around the Luce and Rozan plants at Marseilles and elsewhere in Europe, coming later to Eureka, Nev., in 1878, to operate the Luce and Rozan plant at that point. Mr. Tredinnick was a competent Luce and Rozan operator and being devoted to the process he firmly believed that with modifications the costs could be so lowered as eventually to supplant the Parkes process.

Jan 5, 1917

By Stewart L. Toleman, Robert H. Hafner, Irvin R. Kramer

In his paper on the calculation of harden-ability from chemical composition, Gross-mannl discussed the effect of most of the alloying elements used commercially. The purpose of the work reported in this paper was to determine the effect of several other elements on hardenability—arsenic, antimony, beryllium, cobalt, columbium, germanium, tellurium, tin, aluminum, and titanium—and to extend the range of composition of some of the elements studied by Grossmann—chromium, copper, manganese, molybdenum, nickel and silicon. Experimental Methods To determine the effect on hardenability, suitable amounts of the alloying elements were added to experimental heats and the hardenability determined by means of end-quenched hardenability specimens. The steels were melted in a high-frequency induction furnace with a basic crucible, using ingot iron as a base for some of the heats and S.A.E. 1015 for others. The alloying additions were made as ferroalloys or as metal, depending on the alloying element. Hundred-pound heats were split and poured into square, tapered, cast-iron ingot molds with hot tops. Aluminum was not used as a deoxidizer in most of the heats. The ingots were homogenized for 12 hr. at 1260°C. (23oo°F.) and forged into rounds of I½ -in. diameter. These bars were normalized twice from 840°C. (I55o°F.) before machining into Jominy bars. mined in most Cases by samples taken from the end-quench hardenability spedmen. AS suggested by Crafts,2 acid-soluble (8

Jan 1, 1944

By Robert H. Hafner, Irvin R. Kramer, Stewart L. Toleman

In his paper on the calculation of harden-ability from chemical composition, Gross-mannl discussed the effect of most of the alloying elements used commercially. The purpose of the work reported in this paper was to determine the effect of several other elements on hardenability—arsenic, antimony, beryllium, cobalt, columbium, germanium, tellurium, tin, aluminum, and titanium—and to extend the range of composition of some of the elements studied by Grossmann—chromium, copper, manganese, molybdenum, nickel and silicon. Experimental Methods To determine the effect on hardenability, suitable amounts of the alloying elements were added to experimental heats and the hardenability determined by means of end-quenched hardenability specimens. The steels were melted in a high-frequency induction furnace with a basic crucible, using ingot iron as a base for some of the heats and S.A.E. 1015 for others. The alloying additions were made as ferroalloys or as metal, depending on the alloying element. Hundred-pound heats were split and poured into square, tapered, cast-iron ingot molds with hot tops. Aluminum was not used as a deoxidizer in most of the heats. The ingots were homogenized for 12 hr. at 1260°C. (23oo°F.) and forged into rounds of I½ -in. diameter. These bars were normalized twice from 840°C. (I55o°F.) before machining into Jominy bars. mined in most Cases by samples taken from the end-quench hardenability spedmen. AS suggested by Crafts,2 acid-soluble (8

Jan 1, 1944