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By D. S. Flett, A. W. Fletcher

Equilibrium studies on the extraction of nickel and cobalt with kerosine solutions of naphthenic acid have shown that an exchange extraction reaction occurs at pH 5.5. The nickel/cobalt separation factor is constant at 1.8 for constant total metal molarity and varying nickel/cobalt ratios. The separation factor decreases with increasing total metal molarity in the organic phase beyond 0.2 M and also decreases with increasing temperature. From the equilibrium data, it has been possible to derive a mathematical model for the separation of nickel from cobalt by exchange extraction in multistage systems. Experimental data from a continuously operated multistage mixer/settler apparatus has shown a reasonable correspondence with computer-calculated data. The effective separation of nickel and cobalt in sulfate solution remains a problem in hydrometallurgy and the hope that this would be solved by solvent extraction has not yet been fulfilled. With chloride solutions, advantage may be taken of the ability of cobalt to form anionic complexes with the chloride ion. It can then be readily separated from nickel, which does not form stable chloro complexes, by extraction with a suitable long chain amine. However, in hydro metallurgical operations, sulfate solutions are generally obtained in which no extractable anionic species are present. Thus, the possibility of using cationic extractants must be considered, and in this paper attention is directed to the use of carboxylic acids. The method of separation studied has been termed exchange extraction, which involves replacement of a metal in the organic phase with a more acidic metal in the aqueous phase. Thus, (BR2).+ (Az+)aqt=(AR,).+ (B2+)aq (I) where metal A is more acidic than metal B, R represents the acidic radical derived from the acid RH, and the subscripts e and aq refer to the organic and aqueous phases, respectively. Ashbrook and Ritcey' have used this method for the separation of cobalt from nickel using the sodium salt of di-2 ethyl hexyl phosphoric acid, which preferentially extracts cobalt. Some nickel is coextracted, and this is removed by exchange with cobalt ions in the feed solution by suitable countercurrent operation in a pulsed column. Much work has been carried out by a number of workers in Russia on the general use of exchange extraction for the separation of metal ions using car-boxylic acids. Gindin et aL a have demonstrated that this technique could be applied to the separation of nickel from cobalt using a C--C. carboxylic acid and have applied the technique to the production of high purity cobalt solutions for electrolysis. Further worka was concerned with the development of a process for the separation of nickel from cobalt in a pulsed column. This system permitted the separation of iron and copper from nickel and cobalt in one system. The procedure involved center feeding with acid backwashing at the top and alkali addition lower down the column. Thus the system operated under a pH gradient and the metals were distributed in the column in the order of their basicities. A similar application was studied by Gel'perin et al,4,5 for the removal of copper and iron impurities from a nickel anolyte by means of a C10-C,12 fatty acid fraction. Ginden et al,' and Fletcher and Wilson' have studied the effect of pH on the extraction of a number of metals with carboxylic acids. These studies showed that metals such as iron, copper, lead, zinc, nickel cobalt, and manganese are extracted at pH values close to the pH of hydroxide precipitation. Nickel is extracted at a slightly lower pH than cobalt and thus the nickel/cobalt separation factor has a value not much greater than 1. More basic work on complex identification has been reported by Fletcher and Flett: by Tanaka; and Jay-cock and Jones." These studies have suggested that at low loadings in the organic phase, the nickel and cobalt carboxylates appear to be dimeric and solvated by free carboxylic acid molecules. As the concentration of metal in the organic phase increases, the complex changes and larger polymeric species are formed. In order to permit assessment of the potential of carboxylic acids as extraction reagents for separation of

Jan 1, 1971

OF the many categories into which scientific knowledge has been arbitrarily 'divided, the one that has proved most. applicable in our attempts to gain an insight into the details of steelmaking processes is physical chemistry. To the young metallurgist who has only recently survived a college course in this subject, the application of its principles to reactions in liquid steel should not be difficult. The many excellent textbooks of physical chemistry provide ample material on the principles of this subject for the student of steelmaking processes. It is the purpose of this chapter to provide a concise review of the principles of physical chemistry that have proved useful in studies of steelmaking and at the same time to present some of the data that are essential to the application of physical chemistry to reactions at high temperatures. Certain parts of physical chemistry require rather formidable mathematics for their complete development, but in the main those applications in which we are here interested can be expressed in fairly simple terms. Many of the equations are logarithmic, and we shall use the symbols In X and log X to represent, respectively the natural and the common logarithm of X. The two are related-by In X = 2.303 log X. Logarithms may, be read from a good slide rule with sufficient accuracy for our purposes. In a few spots a knowledge of the calculus will be helpful. MATTER Innumerable forms of matter may, be recognized, and these may be converted by chemical processes into others, as ore, coke, and air are converted into iron, slag, and gas.. Whenever such a change occurs there is a corresponding change in the amount of energy associated with the matter. The process may require an input of energy, as in the electrolytic production of aluminum, or it may result in an output of energy, as in the combustion of fuel. The basic laws of the conservation of matter and of energy tell us that we cannot change the total amount of matter or the total amour t of energy.. When the fuel pile is used up, we realize that it has simply been converted into other forms of matter; .i.e., ash

Jan 1, 1964

By T. A. Rickard

In a former paper* the writer has described the essential features of the general geology of the Cripple Creek region. In the present account it is intended to examine into the occurrence of the ores, the value of which has made this district the most important among existing American gold-fields. The production of Cripple Creek from its discovery, in 1891, to the close of 1901, has reached a valuation of fully $125,000,000. During the past year (1901) the output amounted to $17,285,470. In 1900 it was $18,174,681. The first discoveries, which led to the development of the district, were made in the spring of 1891, but it was not until 1893 that vigorous work was commenced. A great impetus was then given to the exploration for gold on account, of the sudden drop in the market-price of silver, caused by the closing of the Indian mints in the summer of that year. This induced an energetic population from the older silvermining camps of Colorado to go to the new gold-field, which was then beginning to attract attention. Prospecting, at first, was hindered by the comparative absence of outcrops, due to the fact that the surface of the hills is covered with a considerable thickness of shattered rock, resulting from the action of frost at a high altitude; but so much indiscriminate digging was done that a number of rich veins were uncovered, and this stimulated the search for others. The advanced condition of the mining industry of Colorado offered unusual facilities for exploration and reduction; progress was therefore rapid, with the result that the district soon achieved great prominence.

Jan 1, 1903

Jan 8, 1951

Jan 4, 1950

By J. S. Pascover, J. K. Abraham

The influence of the early stages of precipitation on the kinetics and structure of martensite formation in Fe-27Ni and Fe-29.5Ni alloys containing from 0 to 10 pct Ti was examined with X-ray and electron microscopy techniques. The formation of a coherent, ordered preprecipitate had a profound stabilizing effect on the austenite. The Ms was decreased by increased titanium content and aging time up to a critical time. When the critical aging time was exceeded, the Ms was observed to increase markedly. The formation of the clusters was insuppressible and the volume fraction of clusters formed during the quench was a function of the titanium content. Martensite resulting from transformation of the clustered austenite is tetragonal with the c/a ratio increasing with titanium content. A model for the tetragonality is suggested. The morphology and substructure of the m artensite is inter-preted in terms of the above information and the cur-rent models of twinned martensite. ThE ramifications of precipitation in austenite to the properties of austenite have been the subject of numerous investigations. The current research is concerned with the influence of precipitation in austenite on the kinetics and structure of subsequent marten-site formation. In a previous investigation, Abraham et al.1 followed the aging reaction in an Fe-29.5Ni-4.2Ti* (at. pct) alloy using an X-ray diffraction technique. This technique, employing a Guinier camera, provided kinetic measurements through observation of the side band position as a function of aging time. The salient results of this work were: 1) The initiation of precipitation was not suppressed by quenching, i.e., there was a finite cluster zone size at zero aging time; and 2) The hardness of the aged austenite correlated extremely well with the zone size. During the previous work it was noted that the mar-tensite formed after aging was tetragonal, substanti-ating an earlier observation.2 Systematic investiga-tion revealed that the martensite was tetragonal in both the solution-treated then quenched, and the solu-tion-treated, aged, and quenched condition, and, furthermore, that a marked stabilization of the austenite occurred as a function of aging time. The present work is concerned with documenting the tetragonality and the stabilization phenomena as well as the ob- served microstruction with a suggested rationale for the behavior noted. EXPERIMENTAL PROCEDURE The compositions of the alloys are listed in Table I. The analyses were performed after the solution treatment of the strip material. Nickel was determined using the standard dimethy1-glyoxime procedure whereas titanium was determined colorimetrically with hydrogen peroxide and volumetrically by titrating with ferric iron. The materials were melted in a 5-lb vacuum induction furnace, cast into 2-in.-diam ingots, and forged in a temperature range of 950. to 1200°C to 1/2-in. slabs. The three higher titanium containing materials cracked during forging; therefore, to get the alloys into strip form, slices 1/8 in. thick were cut from the slab, homogenized 4 hr at 1150°C, then cold-rolled to a 0.04-in. thickness. The remaining slabs were hot-rolled, homogenized 4 hr at 1065"C, then cold-rolled to a final thickness of 0.03 in. All of the heat treatments were performed under a protective atmosphere of argon. The Ms temperature for most of the alloys is below room temperature; therefore, it was possible to solution treat, quench to room temperature, polish, and then observe the transformation optically on a cold-stage microscope. To determine the effect of aus-tenitizing temperature on Ms, eight of the alloys were treated at two temperatures, 1025" and 1120°C. No measurable variations in Ms were noticed. The remaining alloys were treated at 1025°C. The specimens, : by 5/16 by 0.03 in., were austeni-tized in a vertical tube furnace under a dynamic argon atmosphere. The bottom of the tube was submerged in water for quenching purposes. The question of stabilization that may be operating at room temperature was investigated and found to be negligible. Many of the specimens were held at room

Jan 1, 1970

By J. E. Hove

The high temperature physical properties of graphite are reviewed and interpreted in the light of present day knowledge of the mechanisms affecting these properties. The thermal and mechanical behaviors only are discussed and, whenever possible, comparisons are made with other refractory materials. Possible further studies are indicated, including some carbide work. AS long as the term high temperature implied only temperatures up to about 1000°C, the materials problems which arose could usually be handled by fairly conventional metal alloy types, such as the Co-Cr-Ni superalloys, for which there exists a great deal of technology. Perhaps this temperature can still be considered an upper limit for normal applications, but it is certainly true that the number of abnormal applications is increasing rapidly. The advent, in recent years, of ram-jet and rocket missiles and of high power nuclear reactor heat sources has raised a host of questions concerning the basic problem of what material to use in the temperature range up to 2000°C and higher. While there are, of course, many metals, in the second and third transition series, which melt at considerably higher temperatures than this, these metals are, at present, pretty well excluded from practical use by other considerations, such as re-crystallization, chemical activity, or excessive plastic deformation. The behavior of metals, from the standpoint of dislocation theory, is just beginning to be understood and thus there is some hope for the future development of very high temperature metals, but the immediate problems would most logically appear to have solutions involving the nonmetals, such as the refractory ceramics and graphite. For this reason, there is presently a great deal of engineering and experimental research being performed on the latter materials, much of this research being exploratory in the sense of gathering new property data. The situation, so far as graphite is concerned, is somewhat more fortunate than with the other refractory solids in the sense that a great deal is already known about its basic properties. This stems both from the fact that the carbon-carbon bond has been of interest to chemists for a long time (and graphite can be considered as a very large aromatic molecule, if desired) and the fact that its properties, both as a function of temperature and of radiation damage, are of critical importance to nuclear reactor designers. It is still true, of course, that such fundamental questions as why graphite remains solid to such a high temperature and why it has such a high thermal conductivity cannot entirely be answered at the present time. It is, nonetheless, meaningful and instructive to consider such problems in the light of existing knowledge. This is what the present paper will attempt to do. Before going on, it may be appropriate to classify graphite and justify its discussion before readers primarily interested in metals. Graphite is comparatively unique among materials in that there is always a property or group of properties which precludes calling it either a metal, a semiconductor, or a ceramic. It has the high electrical and thermal conductivities of a metal, but the artificial, poly-crystalline types show a negative thermal coefficient of electrical resistivity, generally characteristic of semiconductors. On the other hand, semiconductors, by definition, show an ever increasing resistivity as the temperature is lowered, whereas graphite approaches a finite, and, indeed, a rather low resistivity in the region of 10°K and, furthermore, a good single crystal of graphite has a positive temperature coefficient, as for a metal.' On still another hand, its porosity and brittleness at lower temperatures would put graphite in the ceramic class although, unlike most ceramics, it is readily machinable and has a high resistance to thermal shock. All things considered, it is probably more nearly appropriate to call graphite a metal than anything else. Although certainly outstanding in some ways, graphite has its peculiarities and, especially if the reader is unfamiliar with the data, it is probably valuable to review some representative property variations at high temperature. This review is meant to be mainly illustrative and no attempt has been made to be exhaustive. Review of High Temperature Properties At ordinary pressures, graphite does not melt, but sublimes directly into the gaseous phase at about 3700°C. Although the phase equilibrium diagram is still in some doubt, graphite will melt, at a slightly higher temperature, at pressures in excess of about 100 atm. The chief difficulty of using graphite in an oxidizing atmosphere is that the reaction rate becomes quite high at fairly low temperatures. If a threshold oxidation temperature2 is defined as the temperature at which graphite loses 1 pet of its weight in 24 hr, the value in air is 450°, the value in steam is 700°, and the value in carbon dioxide is 900°C. Efforts are presently being made to raise this threshold temperature either by impregnation with a retardant of some type (sodium tung-state and phosphoric acid, for example) or by a suitable metal or oxide coating. It is probably fair to say that, to date, these attempts have not shown any outstanding success in all respects. Most commercial graphites are fabricated by impregnating a carbon flour (say of coke or lampblack particles) with some type of hydrocarbon

Jan 1, 1959

By Eugene F. Poncelet

GLASS squares compressed on edge by steel jaws in poor contact with them developed jagged "partial-contact" cracks caused by the formation of local tensile stresses. Compressed by steel jaws in perfect contact, they developed smooth "release cracks" during release of the pressure, caused by the formation of local tensile stresses during the release of the pressure. All these cracks were parallel to the pressure. A Microflash photograph of a disintegrating specimen under sufficient pressure reveals a network of fractures roughly normal to each other, also "release cracks" and a disintegration cloud. The Griffith theory is amended to account for the formation of a first crack. A new theory, based on the theory of thermal agitation and wave propagation, is proposed to account for the progress, velocity and forking of cracks. The network of fractures is shown to have been caused by reflection at a free boundary of pressure pulses emanating from a first crack. Postulating equal distribution of energy in the pulses emitted on either side by a crack in particles, the smaller fragments are shown to continue fracturing preferentially while some of the coarser fragments remain as residual pieces. As comminution of the smaller fragments proceeds, the solid is reduced to a collection of residual particles of smaller and smaller sizes, accounting for the disintegration cloud. EXPERIMENTAL PROCEDURE Apparatus A crushing device was built, consisting of a steel frame and two polished, hardened steel jaws to crush plate-glass samples. This device was placed between the plates of a hydraulic press (Fig. 1). For centering the pressure, the upper jaw was guided vertically and provided with a rounded top. Later it was replaced by a steel jaw ground out of a 2 1/2-in. steel ball, the lower surface being ground to an optical flat (Fig. 2). Four rollers were used to eliminate side thrust. Screws and centering blocks served to center the specimen in the crushing device. Hard steel shims placed under the shoulder of the upper jaw limited the "follow through" of the jaw after failure of the specimen. Stress distribution was first examined with a polariscope mounted on an optical bench, using monochromatic light. It was found convenient to mount polaroid, quarter wave and monochromatic plates directly on the device itself. A Microflash unit* was used as light source for the photographs. A gold-paint pattern was fused on the plate-glass specimens and connected into the spark-

Jan 1, 1944

By Louis Huber

THE Liberty tunnels extend through a very steep hill in Pittsburgh (locally called Mount Washington) for a distance of slightly over a mile. The two tunnels parallel each other and are 59 ft. apart, center to center (Fig. 1). They are for vehicular traffic, and in each there is ample space for two lines of vehicles. Northbound traffic, towards downtown Pitts- FIG. I.-NORTH PORTAL OF LIBERTY TUNNELS. NOTE THE WINDBREAK AT END OFEAST TUNNEL. burgh, is confined to the east tunnel and southbound traffic to the west tunnel. The South Hills residential district is separated from downtown Pittsburgh by Mount Washington, a steeply rising escarpment south of and adjacent to the Monongahela River. The Mount Washington district immediately south of the Monongahela River has been reached, for many

Jan 1, 1927

By R. L. Slobod, C. Gatlin

This .study defines the basic mechanism of the mis-cible displacerrzent of oil and writer from porous Medici by various water-driven alcohol .slugs. Three distinct alcohol slug processes were .studied. Considerable data concerning the quanity of alcohol required for oil recovery were also obtained. All data were obtained in a 1-in. diameter, 100-ft long, unconsolidated core. The porosity of this system was 35 per cent. and the permeability was approxitrlately 4 darcies. Total core pore volume wax 5,716 cc. All displacements were conducted at a constant injection rate of 5 to 6 cc//min, which corresponds to a frontal advance of 5 ro 6 ft/hr. The first portion of this paper is concerned with 111 use of one alcohol—isopropyl—a\. the slug material. Isopropyl alcohol (IPA) is completely miscible with both oil rind water; however, miscibility of the threc-component systems, oil-water-IPA, requires a relutively. high concentration of IPA. Hence, the displocement is not of the misoible type unless the IPA concentration is maintained above some critical value. A slug of IPA equal to only 13.5 per cent of the pore volume was jound to be sufficient to obtain complete recover?, of residua1 naphtha. In later studies two distinct process variations were developed. The firsr of these utilized methyl alcohol (MA) and IPA as slug materials. It was shown that methyl alcohol may he substituted for IPA at the front and rear of the slug with no loss of oil recovery. A .slug of 4 per cent MA-4 per cent IPA-4 per cent MA was sufficient for complere oil recovery. Because MA is considerably cheaper than IPA, this represents an important step toward economic application. A .second process variation used normal butyl alcohol (nBA) and MA as the composite slug, the nBA segnzent being injected first. This technique requires the smallest total slug size (approximately 10 per cent) of all processes studied. The high cost of nBA, however, precludes commercial application. It is possible that this basic process, subject to changes of alcohol type, may lead to a commrercicil process. INTRODUCTION Within the last 10 years, considerable study has been devoted to the general mechanics of miscible phase dis- placements in porous media. These studies have. in general, dealt with two-component displacernent. All reported field trials to date have been modified gas drives of one type or another. These utilize either lean gas at high pressure, rich gas at lower pressure or an LPG slug. The irreducible water content of the reservoir remains immobile during these processes. Although these techniques hold great promise. certain drawbacks do exist. Poor areal sweep efficiency, inherent in any displacement having a highly unfavorable mobility ratio, is one disadvantage. Furthermore, the miscibility of all processes which use gas is dependent on pressure. These pressure limitations may prohibit application to shallow reservoirs. There are also many areas where large quantities of LPG and natural gas are not readily available. These factors emphasize the need for improved techniques. The alcohol slug process is also a miscible-phase displacement process. It differs from the previously mentioned two-component techniques, however, in that both the reservoir oil and water are displaced by the slug. This behavior is a consequence of the miscibility of certain oil-water-alcohol systems. In the simplest case, a relatively small volume (slug) of an alcohol (such as isopropyl) is injected into the system. Water is then used to drive the slug through the medium. Thus. three components—-alcohol. oil and connate water-—exist at the front side of the slug. Miscibility is obtained at some alcohol concentration, this being dependent on the solubility of the particular system. Miscibility is maintained within the slug until the alcohol concentration falls below that value required to maintain miscibility. When miscibility is lost, the process reverts to a water flood. Certain inherent benefits of this technique are apparent. High pressures are not necessary to obtain miscibility in these liquid systems. Furthermore, water is a more desirable driving agent than gas because of the improved mobility ratio and the attendant improvement in areal sweep efficiency. The main disadvantage is, of course, the relatively high cost of alcohols. The use of an alcohol slug to recover reservoir oil is not a new idea." ' However, this process has received only limited study, presumably due to the lack of industrial interest caused by the seemingly prohibitive cost of alcohols. The main purpose of this study was to investigate the mechanism of the displacement of oil and water by various alcohol slugs and to develop process modifications aimed toward possible commercial application.

By John C. Martin

The discovery of a new gas reservoir demands that the planning of a sottnd well-spacing program be initiated early in the development stage. It is the purpose of this discussion to illustrate by actual field examples the application of basic well-spacing principles, previously developed for oil reservoirs, to the problem of well spacing in natural gas fields. These studies are presented for the field use of geologists and engineers who are concerned with the initial planning of the proper development of the newly discovered gas reservoir. INTRODUCTION The phenomenal growth of a vigorous natural gas industry emphasizes the increasing importance of natural gas as a source of energy, fuel, and raw materials to our nation's economy. Since 1945 marketed production of natural gas for the U. S. has increased 21/2 times to a record high of 10.6 trillion cu ft during 1957. As major participants in the gas industry, we share an added interest to develop and produce our natural gas reserves with constantly improved efficiency. The subject of well spacing is vitally important to the gas industry, for the well itself plays a significant role in the development of the natural gas reservoir and in control of the recovery process. Maximum utilization of wells is an integral part of sound conservation practices. The discovery of a new gas reservoir demands that careful choice of well location and well spacing be made and that the planning of a sound well spacing program be initiated early an the development stage. With the drilling of the first development well, efforts of the geologist and engineer must be directed toward acquisition of adequate technical evidence upon which a firm recommendation for a spacing program may be based. With this technical appraisal as a foundation, operators and state regulatory agencies jointly can go far in providing a framework for sound development of gas fields to achieve a program of conservation that avoids the unnecessary well. WELL-SPACING CONCEPTS Through laboratory and field investigations of the mechanism of the recovery of oil and gas, of fluid behavior, and of effective control of reservoir and well, a crystallization of ideas regarding reservoir behavior has emerged as a well-developed technology. Associated with a better understanding of the fundamental principles underlying reservoir and well behavior has been the growth of concepts concerning the role of wells and their spacing in the development and operation of an oil or gas reservoir. In addition to serving as outlets for the withdrawal of fluids from the reservoir, wells are recognized as having two other important functions: (1) providing access to the reservoir to obtain information concerning the characteristics of the reservoir and its fluids, and (2) serving as a means by which the natural or induced recovery mechanism may be effectively controlled. Beyond a minimum number of wells required to fulfill these two functions, additional wells will not increase recovery. With particular emphasis upon well spacing in oil reservoirs, many studies of the well spacing-recovery relationship have evolved the concept that the ultimate oil recovery is essentially independent of the well spacing.' These fundamental concepts are no different when regarding the role of wells and their spacing in the natural gas reservoir. They are equally applicable to the consideration of well spacing in gas reservoirs. For the gas reservoir, the problem of well spacing then revolves around the question of drainage and the degree or extent to which a well may drain gas from its surrounding reservoir environment. Theoretical and Experimental Work During the past 30 years, theoretical and experimental work carried on to study the physical principles involved in the flow of fluids through porous media has shed light upon the matter of drainage. Fundamental mathematical equations have been derived to describe the mechanism of flow of oil and gas through porous rocks. With the recent advent of high-speed digital computers, attempts have been made with mounting success to develop solutions, employing numerical techniques, to mathematical expressions that describe more rigorously the physical behavior and mechanism involved in the unsteady-state flow of compressible fluids, such as a gas, through porous rock. In 1953, Bruce, Peace-man, Rachford and Ricez published a stable numerical procedure for solving the equation for production of gas at constant rate. The results of these calculations are significant with respect to this matter of drainage, for they indicated (1) that depletion of the gas reservoir resulted in a drop in pressure at the extremity of the

Jan 1, 1923

Jan 1, 1923

By R. S. Dean

BLUE HEAT PHENOMENA IN constructing a theory of the flow and hardening of metals, we necessarily make use of such phenomena as seem to be, universally observed in metals. It is, therefore, a matter of. concern to the constructors of such mnemonic systems if one or two of the group classified as metals show anomalous behavior. Such egregious phenomena are observed in pure or nearly-pure iron in the reaction of its mechanical properties to low-temperature annealing after cold work and to increased temperature of testing. In short it has been generally observed that iron," as an outstanding exception among metals, increases its hardness and strength by low-temperature annealing. after cold work,1 and also by increase of testing temperature to the range of 150° to 300° C. The investigation here recorded was made then with the object of ascertaining if similar phenomena were observed in high purity iron and, if not, to the presence of which impurities these phenomena could be traced.

Jan 1, 1929

By Alexander Gow

THE object of this paper is to discuss the fundamental principles of ball milling and to present some observations which have been made in laboratory and plant investigations. The discussion will be limited to wet grinding of ores in cylindrical mills, but doubtless many of the principles involved will be equally applicable in the other fields of fine grinding in which mills of the same type are used. In the concentrators of the United States there are about 650 ball, rod, or pebble mills, operating or ready to operate, and these have about 100,000 connected horsepower. For grinding in cement plants there is about three times this connected horsepower, and other industries have an unestimated amount, all used for the general type of grinding that is to be discussed here. It is true that these figures do not represent stupendous amounts of power, but when one considers that ball milling is often the "bottle neck" in a concentrator and that it often accounts for the largest single item in the cost sheet, the importance of a compre-hensive understanding of the principles of ball milling can be appreciated. Much of the past literature devoted to the subject has been concerned with the Kick-Rittinger dispute over evaluating grinding, or with dissertations on ball paths and the closely allied impact versus attrition hypotheses, or with the exclusive consideration of certain specific varia-bles, such as mill speed or circulating load, irrespective of the other factors in operation. Such subjects may be dismissed with but little discussion in what may be called, by comparison, a new philosophy in the study of ball milling. Briefly, this "new philosophy" consists of using power as an index of the mill operation, and investigating grind-ing from the standpoint of set and induced variables, with emphasis on the latter.

Jan 1, 1934

By H. D. Hoskold

This paper is presented in fulfillment of the promise made in my paper, " Remarks upon Surveying-Instruments,"" etc., and much of the material which would constitute an appropriate introductioil here is omitted, because it has been already published by the Institute, in connection with my own contributions- or those of Mr. Scott and others, in vols. xxviii. to xxxi. of the Transactions, and in the special Institute volume on Mine-Surveying Instruments. In these preceding publications will be found, for instance, descriptions of the writer's " miner's transit-theodolite" of 1863,† and his later " angleometer,"‡ both of which were steps of the progress in engineering instruments and methods which originated in the work of Bourns, before 1842, on the " BoxTunnel " of the Great Western railway in England, in which he had to make connections by direct telescopic sights down the shafts. About 1870 the writer devised a practical and much superior plan, and made detailed drawings for an instrument to meet all the conditions he had proposed prior to that year. The detailed plans were communicated to a celebrated optical firm in London; but, owing to their loss (in Paris or Germany, it is believed) and to other reasons, the matter was, for the time, allowed to lapse. Following upon Bourns's idea, my friend, the late Mr. Beansland, introduced, in 1856, a new system and a portable astronomical instrument.§ Such instruments, however, were neither common nor convenient, and did not come into general use among engineers.

Jan 1, 1902

By R. O. Leach, O. W. Wagner

Because of unfavorable wetting conditions much residual oil is left when a porous material is Pushed by water. Methods suggested to change reservoir wetting to improve oil displncernrnt efficiency are generally expensitlr. The present 1aborator.y study was undertaken to gain an under.standinx of the factors which determine reservoir wettability, arid to find out if oil displacement efficiency might be improved by a wettahility change accomplished at low cost in on oil reservoir. Contact angle measurements were made on mineral surfaces using sevc.r~zl sets of reservoir oil and water samp1es. Results of the contact angle studies suggest that reservoir wetta-hility may he primarily determined by natural surface-active substances present in the reservoir fluids. The effect of changing sa1inity and pH of the water phase was studied. The re.suits suggest that gross changes in preferential wettability might be acc~o~npli.shed by injection of water containing simple chernicnls to alter pH or salinity in the reservoir. Such treatment could he much less expensive than injection of commercial surface-active agents. Waterflood tests have also been made using synthetic cores and oil and water having wening characteristics similar to those of reservoir fluids. Cores initially oil-wet were flooded in such a way that they were made prefermtial1y water-wct by the advancing flood water. This reversal in preferential wettability achieved greater oil displacement efficiency than when either oil-wet or water-wet conditions were maintained throughout the flood. For the systems studied, the higher the oil viscosity the greater the percentage improvement obtained over conventional waterflood recovery. This suggests that a flooding process making use of wettability-reversal may extend the oil viscosity range over which water flooding is attractive. Because a precise adjustment of reservoir wettability does not seem to be required, and because altering the pH or salinity in some reservoirs may be inexpensive, it appears that a waterflooding process employing wet-[ability-reversal could find .succesful field application. I NTRODUCTION The efficiency with which water will displace oil from a porous material is related to the nature of the capillary forces present. These in turn are controlled by the preferential wetting of the solid by the two fluids. Because of unfavorable wetting conditions, 30 per cent or more of the original oil in place may remain unrecovered in that portion of a reservoir flushed by water. This paper is concerned with the possibility of improving waterflood oil displacement efficiency by alterations in the wettability of the porous material. A laboratory study was made to gain a better understanding of the factors which control reservoir wettability, and to determine if the oil displacement efficiency could be improved by some inexpensive means of manipulating wettability of the porous medium. Contact angle measurements were made with several natural and synthetic oil, water and solid systems (1) to obtain a better understanding of how to duplicate reservoir wettability in the laboratory, and (2) to discover possible means for changing preferential wettability of natural reservoir systems. Flooding tests were also made in synthetic systems to determine if oil displacement efficiency could be improved by those wettability manipulations suggested by the contact angle measurements. Based on these studies a possible method for improving waterflood oil displacement efficiency is presented. This method involves causing an originally oil-wet porous material to become preferentially water-wet during the course of a water flood. The purpose of this paper is to present results of the laboratory studies. THEORY Rock surfaces in some oil reservoirs are believed to be covered with a firmly attached bituminous or other organic coating. Such surfaces would be preferentially oil-wet in the presence of both oil and water, regardless of composition of reservoir fluids. Other reservoirs are believed to contain rock surfaces not permanently coated with such materials, and which would be preferentially wet by water in the presence of water and oil free from surface-active substances. However, when the reservoir fluids do contain certain natural surface-active materials in sufficient quantity, rock surfaces acquire a degree of preferential oil wettability caused by adsorption of these natural surface-active materials on the solid. The equilibrium amount of these materials adsorbed per unit surface area is believed to depend upon their concentration in the bulk liquid phases.

By Christopher W. Schram, Allan B. Tanner, Frank E. Senftle, George R. Boynton, Philip W. Philbin

Abstract-A borehole sonde wing a 252Cf neutron source and a Ge(Li) gamma-ray detector was field tested in a coal bed in Belmont County, Ohio, to ascertain whether such a device could be useful as a coal-exploration tool. As the sonde was lowered into the borehole, successive spectra were accumulated over short time intervals. The intensities of the capture gamma rays from hydrogen and of decay gamma rays from aluminum were determined simultaneously in each spectrum. A log of the intensities versus depth shows the depth and thickness of the coal bed.

Jan 6, 1978

By Arhtur T. Allen

THE Kingsport formation, a part of the Knox dolomite of Ordovician age, is composed of 538 ft of dolomite and limestone. Numerous bands, layers and nodules of chert, arenaceous and shale zones are present. The characteristics displayed by these features have been useful in mapping, prospecting and mining. Perhaps a better understanding of the origin of these zones will increase their usefulness.

Jan 1, 1947

By J. C. Bartlett

As American students of mining, philosophy, philology, music, history, or art have found it necessary or highly advantageous to supplement their course of study at home by a residence of some years at a foreign university, so, ever since mining has been practiced in this country in any other than a rude and wasteful manner, many American students of mining have sought in London or Paris, but chiefly in the Academy of Freiberg, Clausthal, or Berlin, such infor-