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By A. D. Marriott, J. V. N. Dorr

This paper reviews recent developments in the application of classification practice to the origination of fine-grinding flow sheets and traces the history of the mechanical classifier from its initial application for separating cyanide process sands and slimes down to its present six or more distinctly different applications at copper concentrators; it undertakes to show also, by reference to diagrammatic fine-grinding flow sheets and accompanying operating data from nine copper concentrators in western North America, the advantages gained from improved classi-ficiation flow sheets at these properties in terms of reduced grinding costs, improved flexibility of operation or increased recovery. Comparison is only made between different fine-grinding flow sheets at a given plant and no attempt is made to compare different concentrators, on account of ore variations and differences in metallurgical objectives sought,. The adoption of the flotation process in recent years, and especially the development of selective flotation, has brought a demand for much finer grinding than formerly. This has caused much thought to be given to grinding efficiency, and today there is hardly a mill where the grinding flow sheet is not under close study and subject to frequent changes. When closed-circuit grinding was introduced into metallurgy some years ago, its value was recognized at once, and since then the combination of mills and classifiers has been regarded and operated as a grinding unit. Apart from variations in both the grinding and classifying elements of this unit, there have been many variations in grouping tried by different mills to suit varying conditions of ore and plant limitations. Although operators feel that in most cases their present flow sheets are on trial, and the data on present work are often incomplete, we have felt that a discussion of the progress that has been made and an endeavor to show present trends and their results should be of use to the profession. We have therefore prepared flow sheets of some of the larger mills with which we have been in contact and present them with available data as to their results, in the hope that they may be of service now rather than later when practice may have become more standardized and more complete records and analyses have been made. We believe that the data given,

Jan 1, 1930

By R. V. Higgins, A. J. Leighton

A fast method is needed for calculating thoroughly the performance of two-phase flobr~ in reservoir rock with complex geotrietry. The authors present such a method and .slzow its accuracy by romparison with laboratory performrrnce of a five-spot pattern. In making the performance c.alculations, the octant of the five-spot pattern was divided into four channels. The computer tinle required for the culculation was one rllinrcte. This is rorighly about minute per channel. INTRODUCTION By using an electronic computer it is now possible to make reservoir performance calculations in which fewer assumptions and more significant variables are included than was possible with a desk calculator. These performance calculations include such variables as the properties of the reservoir rock and its contained fluids, properties of the rock-fluid system and even different well-spacing patterns. Usually, the more variables that are included the higher the computer cost—and time on the computer is expensive. As a result, a short procedure is needed so the many variables will be included and accurate performance calculations will result. If a reservoir is composed of alternate layers of permeable and impervioi~s rock, and if each conducting layer has a different relative permeability, the combined computer cost for calculating each layer by the present long computer programs (which includes different well-spacing patterns and other variables) would be expensive. The performances of complex spacing patterns in a field often are studied by a potentiometric model, but in these model studies the analogy is to the flow of only a single phase. This paper presents a procedure to calculate the performance of a five-spot pattern with two phases flowing using a potentiometric model as a guide for the dimensions of channels and other related data. The time required to calculate the complete performance is about one minute on the IBM 7090 or four minutes on the IBM 704. The procedure can be extended to calculate the performance of more complex well spacings or an entire field with little modification. The procedure has been tested on the performance of the laboratory water floods of a five-spot pattern reported by Douglas, et alThe range of viscosity ratios in the laboratory experiments is from 0.083 to 754, which is extensive. The accuracy of the performance calculations is excellent as shown by the plotted points in Fig. I. The recovery as influenced by the geometry of the five-spot, taking into account the deviation from true radial character, has been predicted by Aronofsky and Ramey." The authors used a potentiometric model to determine the sweep efficiency to breakthrough of the flooding agent. Dyes, Caudle and Erickson,' by means of a laboratory model, show the influence of mobility ratio on recovery after breakthrough of the injected material. Dyes, et ai, used the X-ray shadowgraph technique and miscible phases in their studies. Craig, Geffen and Morse from the analysis of the performance of their laboratory model correlate many variables, including average saturation of a flooding agent determined by permeability relationship. Craig, et al, used X-ray shadowgraphs to determine the sweep efficiencies in sandstone models. In this report the sweep efficiency is not needed, and the important effect of continuously changing saturation gradients before and after breakthrough

By Charles Miller

Natural carbon dioxide has recently been exploited in the United States in consequence of oil and gas developments in the Western States and the growing demand by transcontinental and transoceanic shippers for solid carbon dioxide. The discovery by drilling of commercial deposits resulted in consideration of its geographic and geologic distribution and occurrence. Its wide distribution in nature is evidenced by its occurrence in the atmosphere, hydrosphere and lithosphere. The question of origin of carbon dioxide involves consideration of theories similar to those concerning natural hydrocarbons, although available evidence favors an inorganic rather than an organic source. Areas favorable to development of commercial production appear to be those in proximity to igneous rocks or in the vicinity of decadent volcanic activity, where, it has long been known, the gas is evolved either free or dissolved in the waters of fumaroles, geysers or mud pots. Structure contour maps are presented showing the Wagon Mound anticline in New Mcxico and the Farnham anticline, Utah. A well drilled on the latter supplies gas to a 20-ton plant manufacturing solid curbon dioxide at Wellington, Utah, on the Denver and Rio Grande R.R., whence it is shipped to surrounding territory and to the West Coast. Before funds are invested in a plant for the manufacture of liquid or solid carbon dioxide, whether supplied by wells or springs, an effort to ascertain the volume of gas available is advisable. The use of present methods of estimation of gas reserves with modifications to account for the quantity absorbed by any water present in the producing formation is recommended. The Farnham anticline is used as an example and computations are made of the probable volume of gas originally present in the structure. No attempt was made to compute reserves in the Niland area, California, for the reason that in such areas it is believed the volume is indeterminate. Introduction Carbon dioxide, in liquid and solid form, has found a wide variety of uses other than its primary application in carbonating beverages. It is now used in more than 40 different ways, ranging from cooling or freezing to use in gas or liquid form for mechanical purposes, chemical industry, explosive, fire extinction, and tire manufacturing. Undoubtedly the chief supply of carbon dioxide is obtained from industrial plants or artificial sources and until recently natural deposits of the gas have received little consideration. Few will question the utility and perhaps dependability of artificial sources, which possess the advantage over

Jan 1, 1938

By Charles Miller

Natural carbon dioxide has recently been exploited in the United States in consequence of oil and gas developments in the Western States and the growing demand by transcontinental and transoceanic shippers for solid carbon dioxide. The discovery by drilling of commercial deposits resulted in consideration of its geographic and geologic distribution and occurrence. Its wide distribution in nature is evidenced by its occurrence in the atmosphere, hydrosphere and lithosphere. The question of origin of carbon dioxide involves consideration of theories similar to those concerning natural hydrocarbons, although available evidence favors an inorganic rather than an organic source. Areas favorable to development of commercial production appear to be those in proximity to igneous rocks or in the vicinity of decadent volcanic activity, where, it has long been known, the gas is evolved either free or dissolved in the waters of fumaroles, geysers or mud pots. Structure contour maps are presented showing the Wagon Mound anticline in New Mcxico and the Farnham anticline, Utah. A well drilled on the latter supplies gas to a 20-ton plant manufacturing solid curbon dioxide at Wellington, Utah, on the Denver and Rio Grande R.R., whence it is shipped to surrounding territory and to the West Coast. Before funds are invested in a plant for the manufacture of liquid or solid carbon dioxide, whether supplied by wells or springs, an effort to ascertain the volume of gas available is advisable. The use of present methods of estimation of gas reserves with modifications to account for the quantity absorbed by any water present in the producing formation is recommended. The Farnham anticline is used as an example and computations are made of the probable volume of gas originally present in the structure. No attempt was made to compute reserves in the Niland area, California, for the reason that in such areas it is believed the volume is indeterminate. Introduction Carbon dioxide, in liquid and solid form, has found a wide variety of uses other than its primary application in carbonating beverages. It is now used in more than 40 different ways, ranging from cooling or freezing to use in gas or liquid form for mechanical purposes, chemical industry, explosive, fire extinction, and tire manufacturing. Undoubtedly the chief supply of carbon dioxide is obtained from industrial plants or artificial sources and until recently natural deposits of the gas have received little consideration. Few will question the utility and perhaps dependability of artificial sources, which possess the advantage over

Jan 1, 1938

By Fernando A. Buttazzoni, Jorge C. Munita

INTRODUCTION To provide a background for discussing long-range financial and operational planning in the mining industry, we would like to begin by describing the role of planning in Codelco. Having taken part in Codelco's planning process since its inception in 1976, we believe that useful conclusions may be drawn for the experience we shall relate. Although Codelco is a state-owned copper producer with an important role in the Chilean economy, and is consequently very much at the core of national economic planning, the following discussion is not related to government planning but to planning in an operationally and commercially autonomous business concern with all the characteristics of a private enterprise. The only way in which Codelco differs from private business is that its financial successes or failures have a more direct impact on the countryls ability to participate in international trade, to meet its international financial commitments and to achieve economic and social growth. Thus, what follows is a presentation of the conceptual features of the planning process at Codelco and a description of the current state of planning in the company. It is understood that certain conceptual components are basic to any formal strategic planning process, and that the components of Codelco's planning process are therefore generally applicable in similar companies. First, the mission and scope of operation of the company must be defined, and goals must be set to achieve leadership in the business activities in which it engages. Having set this framework, the company must constantly scrutinize those internal elements and conditions that are essential to fulfill its mission and achieve leadership. In Codelco this means considering the actions which can best serve to define future capacities, taking into account declining ore grades and determining optimal production levels; watching over the productivity and skills of its labor force, and; keeping abreast of technological developments in non-ferrous mining and processing. If the company is proficient in these three areas, it will be cost efficient and there- fore competitive. Codelco must also watch over the business environment in which it operates. The company sells concentrate, blister and fire-refined copper, wirebar, cathodes and wire rod and must study the behavior of the market to attune its product mix to the demand existing for these various commodities in the international market and the copper consuming industries in general. By examining the internal and external environment in which the company conducts its production and commercial operations, it is able to diagnose its strengths and weaknesses, to identify the hazards it must overcome to stay ahead in the copper trade, and to take full advantage of business opportunities as they arise. CHARACTERISTICS OF CODELCO-CHILE Although our subject is Codelco, readers should keep in mind that there are many other copper producing operations in Chile, all in the private sector, and many valuable deposits that may be exploited in the future. Codelco is the only public sector copper producer, although there is one other state enterprise that operates smelting and refining facilities principally to serve a large number of very small producers of copper concentrate. In the mid-19801s, Codelco is the largest copper mining company of the world and the largest producer and exporter of copper with yearly sales totalling close to US$ 1.8 billion in 1983. Moreover, it is a highly profitable copper company at a time when the world copper industry as a whole has reported losses for several years. Codelco-Chile is a fairly new organization. The history of the four mining operations it manages is much longer: El Teniente was opened in 1912, Chuquicamata in 1915, Salavador in 1959 -- with installations of the old Potrerillos mine dating from 1927 -- and Andina in 1970. Having had separate owners, the management systems of the

Jan 1, 1985

By C. M. Wayman, J. F. Breedis

The crystallography of the martensitic transformation in the Fe-30 Ni alloy was reinvestigated. The scatter in the habit Plane as determined from measurements on the mid-rib plane was smaller than reported previously, and the orientation relationship was determined from a martensite plate having known direction cosines. From agreement with crystallographic theory and from observations of the morphnlogy of the martensite plates, it is suggested that the mid-rib plane represents the starting region of the transformation. THE crystallography of the martensitic transformation in the iron-nickel system has been the subject of many investigations.&apos;-7 However, for iron alloys containing approximately 30 wt pct Ni, a wide scatter in the reported habit planes exists. In only one instance has a Laue determination of the orientation relationship been made, but the habit plane of the martensite plate studied was not determined experimentally. Because the most successful thermodynamic and kinetic analyses8 of the martensite transformation have been based on Fe-30 Ni alloys, it was considered desirable to reinvestigate the crystallographic features of the transformation in this alloy. Lieberman9 suggested that the most significant information for use in a theoretical treatment involves the determination of all the crystallographic observables from a single plate of the product phase. This was first done in essence by Greninger and Troiano10 for Fe-22 wt pct Ni-0.8 wt pct C, and is the method followed in this investigation. Some theoretical approaches11-13 in describing the martensitic transformation consider the overall transformation distortion to be comprised of a Bain distortion, or lattice deformation (PI, which produces the structure change, and a lattice invariant deformation (G), such as twinning, which together leave the interface or habit plane un-distorted. The incorporation of a rigid body rotation (R) results in a transformation distortion (E) such that the interface plane is left both undistorted and unrotated. In matrix notation, E = RPG where the lattice invariant deformation has "taken place" in the austenite. Bowles and Mackenzie14-16 in formulating a theoretical approach proposed an adjustable scaler quantity, denoted as 6, which represents a uniform dilation in the interface plane. This dilation acts to adjust the lattice spacings of the parent and product structures at the plane of contact. Using the dilation parameter as a variable, these authors were able to account for a continuous variation of habit planes in steels along a curve in the stereogram between {225}A and {259}A. she invariant line strain14 of the transformation is 6 RP, and the corresponding transformation distortion is E/6.) With the dilation parameter known, the invariant line is computed as the triple coincidence of the habit plane, the shear plane of the lattice invariant deformation, and the initial Bain cone.14 The contraction axis for the Bain distortion can be taken9&apos;17 as [010]A, and the correct permutation of the habit plane indices used. Kelly and Nutting 18 have established the shear plane (of twinning) in the tetragonal martensite of Fe-22 Ni-0.8C to be {112)M by means of transmission electron microscopy. The reasonable shear system is then {112}M which is equivalent to {011}A <01l>A. The as-

Jan 1, 1962

K. Baumgarten has returned from active service in France. He reports that he saw C. W. Campbell, formerly with the 2d Engineers on the Chateau Thierry front, and believes that the latter returned to the United States on August 1. He also saw J. J. Croston; G. J. Sielaff, recently transferred to the Gas Service; Thomas M. Smither, survivor of the Tuscania after a 10-mile swim to Ireland. While in Paris he en-deavored to see Prof. Sauveur, but was unsuccessful. F. K. Borrow was given a commission as Lieutenant in the Royal Garrison Artillery in 1914, but had to relinquish it, on account of ill health, in August, 1915. His health has much improved and he hopes to resume active work toward the end of this year. Davis, A. W:, see British Columbia Engineers, below. Alfred Fox, Jr., enlisted in the Public Schools Brigade, Royal Fusiliers, in September, 1914; was gazetted Lieutenant in the Royal Field Artillery in December, 1914, promoted to Captain in November, 1915, and Adjutant to 78th Brigade, Royal Field Artillery, in January, 1916. He was appointed Staff Captain of the 12th Divisional Artillery in November, 1917. He has served continuously in France since July 1, 1915. He was awarded the Military Cross in January, 1917, and four times mentioned in despatches. E. Fraser-Campbell writes that he joined the London University 0. T. C. in January, 1918, for five weeks; enlisted with the Argyll and Sutherland Highlanders in February, 1918, and attended a training course for officer cadets at Chatham for six weeks. He was commissioned 2d Lieutenant, Royal Engineers, in April, 1918. After two months on home training at Chatham, he landed in France on June 23, 1918, posted to 180th Tunnelling Co., R. E., and is now with his unit up on the line.

Jan 10, 1918

By Cyril Stanley Smith

On the 6th of February 1684, Dr. Martin Lister mentioned at a meeting of the Royal Society1 that "brass is magnetical," and promised to give an account of that assertion at some other time. He repeated his promise but never fulfilled it, and it was left for William Arderon2 to show, in 1758, that brass could be made magnetic by hammering and that it would retain polarity after magnetizing. Twenty-seven years later Caval103,4 examined the matter in great detail. Working with cast calamine brass, he showed that it could be made magnetic by hammering and nonmagnetic by subsequent annealing at a red heat. He found that annealing at a very high temperature caused the samples to lose their magnetic quality permanently, even after subsequent cold-working, but that remelting and cold- working restored it. He encountered some samples of brass that could not be rendered - magnetic by any treatment. Experiments in which these were remelted with iron additions gave negative results, and Cavallo concluded that iron impurity was not the cause of the magnetism. He worked with 50-grain (3-gram) samples melted under the blowpipe, hence cooled very quickly. Bennet5 made whole crucible charges from copper and zinc, and found _ the resulting brass ingots to be magnetic only when iron had been added and then only after cold-working. All these observations applied to material in the cast condi- tion, in which coring would produce a continuous spectrum of composition and cooling would result in varying degrees of precipitation. This knowledge of the subject seems to have been forgotten in the nineteenth century. The older brass was made by the calamine process and frequently contained iron in amounts of 0.5 per cent or more, absorbed from the impure ore with which the copper and charcoal were heated in making the brass. When metallic zinc became available in commercial quantities, calamine brass gradually disappeared, and with it the knowledge of its curious magnetic properties. Only when sensitive apparatus replaced the compass needle of the earlier investigators could the effects be detected in relatively pure metal. The effect of cold-working in inducing ferromagnetism was rediscovered by Bitter8 in 1930 in a sample of impure copper, and this was confirmed by Lowance and Constant: Honda and Shimizu, l0,11 and others. In the same year, Tammann and Oelsen12 showed that copper-rich copper-iron alloys after certain heat-treatments could be rendered ferromagnetic or made more strongly ferromagnetic by cold-rolling. Kussman and Seeman13 showed that the change of susceptibility of relatively pure copper on cold-working was associated with the iron content, and concluded that actual precipitation of iron was caused by cold-working, which is a satisfactory theory until one considers the improbably high rate of diffusion that this would involve. When studying precipitation phenomena in

Jan 1, 1942

By Cyril Stanley Smith

On the 6th of February 1684, Dr. Martin Lister mentioned at a meeting of the Royal Society1 that "brass is magnetical," and promised to give an account of that assertion at some other time. He repeated his promise but never fulfilled it, and it was left for William Arderon2 to show, in 1758, that brass could be made magnetic by hammering and that it would retain polarity after magnetizing. Twenty-seven years later Caval103,4 examined the matter in great detail. Working with cast calamine brass, he showed that it could be made magnetic by hammering and nonmagnetic by subsequent annealing at a red heat. He found that annealing at a very high temperature caused the samples to lose their magnetic quality permanently, even after subsequent cold-working, but that remelting and cold- working restored it. He encountered some samples of brass that could not be rendered - magnetic by any treatment. Experiments in which these were remelted with iron additions gave negative results, and Cavallo concluded that iron impurity was not the cause of the magnetism. He worked with 50-grain (3-gram) samples melted under the blowpipe, hence cooled very quickly. Bennet5 made whole crucible charges from copper and zinc, and found _ the resulting brass ingots to be magnetic only when iron had been added and then only after cold-working. All these observations applied to material in the cast condi- tion, in which coring would produce a continuous spectrum of composition and cooling would result in varying degrees of precipitation. This knowledge of the subject seems to have been forgotten in the nineteenth century. The older brass was made by the calamine process and frequently contained iron in amounts of 0.5 per cent or more, absorbed from the impure ore with which the copper and charcoal were heated in making the brass. When metallic zinc became available in commercial quantities, calamine brass gradually disappeared, and with it the knowledge of its curious magnetic properties. Only when sensitive apparatus replaced the compass needle of the earlier investigators could the effects be detected in relatively pure metal. The effect of cold-working in inducing ferromagnetism was rediscovered by Bitter8 in 1930 in a sample of impure copper, and this was confirmed by Lowance and Constant: Honda and Shimizu, l0,11 and others. In the same year, Tammann and Oelsen12 showed that copper-rich copper-iron alloys after certain heat-treatments could be rendered ferromagnetic or made more strongly ferromagnetic by cold-rolling. Kussman and Seeman13 showed that the change of susceptibility of relatively pure copper on cold-working was associated with the iron content, and concluded that actual precipitation of iron was caused by cold-working, which is a satisfactory theory until one considers the improbably high rate of diffusion that this would involve. When studying precipitation phenomena in

Jan 1, 1942

By H. H. Richardson, E. H. Dix

Of all the alloying elements used in commercial aluminum alloys, copper stands out as by far the most important, and it is perhaps for this reason that the constitution of the aluminum-copper system has received the attention of a number of experimenters covering a period of approximately 20 years. It would be expected that during this time the equilibrium relations would have been thoroughly and exactly worked out. In a general way this is true, but there is a surprising lack of agreement in the details of the high aluminum end of the diagram, particularly in regard to the solid solubility of copper in aluminum, which has been given variously as 2 per cent. to 5 per cent. at the eutectic temperature. The importance of this is much greater than might at first appear to one unfamiliar with modern commercial aluminum alloys. This is true because, with one exception, the susceptibility of the strong alloys to heat treatment depends, in part at least, upon the solid solubility relations of copper in aluminum. In 1919, Merica, Waltenberg, and Freeman1 published the first detailed information on these solubility relations. They found that the solubility of copper decreases with falling temperature from about 4 per cent. at 525" C. to about 1 per cent. at 300" C. and is apparently still diminishing at lower temperatures. In 1921 there was published a brief account of the results obtained in the National Physical Laboratory, Teddington, England.2 This laboratory, however, reported that 5 per cent. of copper is soluble in aluminum at 540" C., and that this amount decreases to about 3 per cent. at 20" C. In the same year Ohtani and Hemmi3 reported a solubility of 4.8 per cent. copper at 520" C., 2.6 per cent. at 460" C. and 1.5 per cent. at 420" C.

Jan 1, 1926

By James J. Halbouty, Michel T. Halbouty

Drilling activity in the South Texas area, which includes the South Corpus Christi and Laredo districts, showed a marked decline during 1941 from that of the preceding year. The rate of new discoveries, however, &apos;compared favorably with exploratory results of 1940 because of the many new productive sands opened in existing fields. South Texas completions for 1941 were about 12.3 per cent below the 1940 figure, compared with an increase of approximately 5.5 per cent in the total number of completions in the United States during 1941 over the 1940 total. During the year, 1452 wells were drilled in this area; of these, 1205 were drilled in or as extensions to the proven fields, and 247 were rank wildcats drilled in search of new producing pools. The comparable 1940 figures were: 1320 field or extension wells and 336 rank wildcats, a total of 1656 completions. This represents a decline in 1941 of approximately 8.7 per cent in proven-area wells, and of about 26.5 per cent in rank wildcats. It must be stressed that wells that were considered rank wildcats at the beginning of operations, but which opened production later classified as additions to existing fields, are not regarded as rank wildcats in this and previous annual reports on this same area. These wells are classified as semiwildcats (Table 2). There were 13 new oil or distillate fields and 4 new gas areas opened during the year, as listed in the next column. This listing represents a decline of 32 per cent from the 25 new areas found during the previous year, and to a great extent can be attributed to the 26.5 per cent decline in wildcatting. The rate of new discoveries based on the 247 wildcats was 14.5 to I, which compares somewhat unfavorably with the 13.4 to I ratio obtained in 1940 (Table 5). Dry wildcats totaled 230. The proof of the prolific character of the South Texas area as a source of petroleum reservoirs is to be found in the fact that of the 1205 field or extension (semiwildcat) wells completed during the past year 61 opened production from new sands or found crude in formerly distillate-producing sands. The 1940 total of 1320 such wells accounted for 50 horizons that provided either new production or crude in distillate sands, and in this respect the 1941 rate of discovery shows to greater advantage, the ratios for new sands being 19.7 to I for 1941 and 26.4 to I for 1940. The 1205 field or semiwildcat wells completed in 1941 resulted in 926 oil or dis-

Jan 1, 1942

By James J. Halbouty, Michel T. Halbouty

Drilling activity in the South Texas area, which includes the South Corpus Christi and Laredo districts, showed a marked decline during 1941 from that of the preceding year. The rate of new discoveries, however, &apos;compared favorably with exploratory results of 1940 because of the many new productive sands opened in existing fields. South Texas completions for 1941 were about 12.3 per cent below the 1940 figure, compared with an increase of approximately 5.5 per cent in the total number of completions in the United States during 1941 over the 1940 total. During the year, 1452 wells were drilled in this area; of these, 1205 were drilled in or as extensions to the proven fields, and 247 were rank wildcats drilled in search of new producing pools. The comparable 1940 figures were: 1320 field or extension wells and 336 rank wildcats, a total of 1656 completions. This represents a decline in 1941 of approximately 8.7 per cent in proven-area wells, and of about 26.5 per cent in rank wildcats. It must be stressed that wells that were considered rank wildcats at the beginning of operations, but which opened production later classified as additions to existing fields, are not regarded as rank wildcats in this and previous annual reports on this same area. These wells are classified as semiwildcats (Table 2). There were 13 new oil or distillate fields and 4 new gas areas opened during the year, as listed in the next column. This listing represents a decline of 32 per cent from the 25 new areas found during the previous year, and to a great extent can be attributed to the 26.5 per cent decline in wildcatting. The rate of new discoveries based on the 247 wildcats was 14.5 to I, which compares somewhat unfavorably with the 13.4 to I ratio obtained in 1940 (Table 5). Dry wildcats totaled 230. The proof of the prolific character of the South Texas area as a source of petroleum reservoirs is to be found in the fact that of the 1205 field or extension (semiwildcat) wells completed during the past year 61 opened production from new sands or found crude in formerly distillate-producing sands. The 1940 total of 1320 such wells accounted for 50 horizons that provided either new production or crude in distillate sands, and in this respect the 1941 rate of discovery shows to greater advantage, the ratios for new sands being 19.7 to I for 1941 and 26.4 to I for 1940. The 1205 field or semiwildcat wells completed in 1941 resulted in 926 oil or dis-

Jan 1, 1942

By J. M. Dumore

If in a vertical, downward miscible displacement, the transition zone between the displacing and displaced fluids is neglected, a criterion for stable displacement can be obtained by considering a small hypothetical protrusion of one of the fluids into the other. This criterion leads to the definition of the well-known critical rate, uc = kg p/p. The consideration is further extended by taking into account the transition zone that develops as a result of diffusion and mixing. A generalization of the previous criterion leads to the definition of another characteristic rate, the stable rate, which in actual miscible drives will be less than the critical rate. In such drives, the entire transition zone is stable at rates less than the stable rate. At rates between the stable and critical rates, the displacement is only partly stable, i.e. part of the transition zone adjacent to the displaced fluid is in an unstable position. From that part of the transition zone viscous lingers will develop. At rates greater than the critical rate the entire displacement is unstable and viscous lingers will develop more strongly. Results of laboratory experiments are in agreement with the expected behavior based on the theoretically deduced stability of the displacement. INTRODUCTION The simplest form of miscible drive in an oil-bearing formation is the injection of a fluid that is completely miscible* with the oil under reservoir conditions. In general, such a fluid, a solvent for example, is less dense and less viscous than the oil present in the formation. If it is injected into a horizontal homogeneous layer, gravitational forces will lead to the formation of a gravity tongue of solvent in the upper part of the layer and the adverse solvent-oil viscosity ratio will cause viscous fingers to develop. If, however, the solvent is injected up-structure into ,a dipping layer, gravity has a favorable effect, because it tends to keep the less dense solvent up-structure. Tongue formation and viscous fingering are consequently reduced and it is even possible that they will be suppressed completely. Viscous fingering and gravity tonguing are the consequences of the instability of the displacement. A stable displacement cannot result in growing viscous fingers and/or growing gravity tongues. Since large amounts of oil can be bypassed if there is viscous fingering and/or gravity tonguing, the stability of a miscible drive is very important with respect to the recovery efficiency of the drive. The stability is of particular importance in miscible-slug drives, as it determines how quickly the miscible slug between the displaced and displacing fluids will be distorted and broken up, after which the drive is no longer completely miscible. Stability is thus a most important factor in determining the success of a miscible drive, and it is considered that the aspects of stability considered in this paper will make a useful contribution to existing theories. Consideration is given only to vertical downward displacements, in which no gravity tongues can develop and which are therefore simpler than downward displacements in sloping layers. THEORY CRITERION FOR STABLE DISPLACEMENT Let us consider a vertical column of a homogeneous permeable medium saturated with oil. A solvent less dense and less viscous than the oil is injected at the top of the column at a constant rate; in the column the velocities of oil and solvent are assumed to be uniform. Diffusion and mixing of oil and solvent will at first be neglected, i.e. we assume that solvent and oil are divided by a sharp interface. An additional assumption is that the interface is horizontal. Continuity of pressures exists at the interface, because no capillary forces are present between the two miscible fluids. Consequently, at the interface (Z = I)):** Ps = Po - P-where Ps is the pressure at the solvent side and

Jan 1, 1965

By R. F. Mehl, G. V. Smith

THE decomposition of austenite in steels, because of its immense practical importance, has been subjected to extensive study in recent years from the point of view of the mechanism of the process.1-3 Although much information has been acquired, a number of questions, principally of theoretical interest, remain. One is that of the atomic-crystallographic mechanism by which each of the various reaction products forms. The isothermal reaction products of the eutectoid decomposition in plain carbon steels (to which this study is restricted) have conveniently been classified in three general groupings-pearlite, bainite, and martensite. Of these several products, pearlite and martensite have been studied extensively, but bainite has received only scant attention. As a result, the mechanism of the formation of pearlite and that of martensite are now fairly well understood while a great deal of uncertainty exists regarding bainite. PEARLITE Pearlite forms from austenite by the precipitation of alternate platelets of cementite and ferrite, which grow into the austenite matrix .2-5 The rate of reaction may be described in terms of a rate of nucleation and a rate of growth.2.3 Mehl and Smith6 have attempted to determine the lattice relationships existing between the ferrite in pearlite and the parent austenite. Using a pole-figure method of analysis, it was found that a limited number of ferrite orientations resulted from the decomposition of a single grain of austenite; it was not possible, however, to decide between two assumed ideal relationships, both of which appeared to account for the experimentally determined pole figure. It was definitely shown, however, that the relationship obtaining was quite different from that determined for the proeutectoid separation of ferrite.7 No attempt was made to determine the habit plane (matrix plane to which the precipitate lies parallel) of the pearlite lamellae. Belaiew8 earlier had stated that the number of directions assumed by the pearlite lamellae in a single grain of austenite was 12 (no details were given) and concluded wrongly, as Mehl and Smiths have pointed out, that the lamellae delineate the [210] planes of ferrite.* MARTENSITE It is known that martensite is a transitional constituent of body-centered tetrag-

Jan 1, 1942

By Heinrich Ries

The clay-resources of Colorado are but little known, for the reason that little has been published concerning them, and also on account of the hitherto small demand for clay products in the Rocky Mountain region. At the present day the wares manufactured from clay which are used in Colorado include common and pressed brick, terracotta, sewer-pipe, pottery and refractory articles. Most of these are brought from a considerable distance; but with an increasing demand for such goods in the West and a better knowledge of the available materials, there should be considerable expansion in the clay-working industry of Colorado in the future. The notes here presented are an abstract of those collected by the writer in October, 1896, in a reconnaissance of the clay-bearing formations of Colorado. Clay-bearing Formations. We may roughly divide the clay-bearing formations of Colorado into three groups : 1. Loess and alluvial deposits. 2. Jura-Trias and Cretaceous clays. 3. Tertiary clays. . The loess forms an extensive deposit of large area, though not very thick, extending from north to south across the State, and eastward from the foot-hills. It is generally a very sandy clay, with little plasticity, and is underlain by a gravelly stratum, which determines the workable depth. Clay similar to the loess is found underlying the river terraces in many of the broader valleys, such as those of the Arkansas, Grand River, etc. The Mesozoic formations extend along the eastern edge of the Rocky Mountains, and also occur in some of the deeper valleys tributary to the foot-hill belt. They consist of a great series of interbedded shales, sandstones and limestones of Jura-

Jan 1, 1898

By A. D. Mutch

IT has long been known that there are wide variations in the thermo-electric potential of pyrite. In the last few years a study of this variation and other properties of pyrite was carried out at the University of Toronto by F. G. Smith on specimens of pyrite from many localities.1-3 As a result of these studies the pyrite geothermometer was developed by Professor Smith. The calibration of the pyrite geothermometer is based on the assumption that "crystals of any one electronically conducting mineral species deposited at a high temperature have a more positive thermo-electric potential than crystals deposited at a low temperature, and the thermo-electric potential varies continuously between any given limits of the temperature of deposition." The cause of the variation was postulated to be crystal discontinuities, such as lineage boundaries. As yet this postulated relationship has not been established as fact. On theoretical grounds it is indicated that the thermo-electric potential of pyrite or any other partial conductor is dependent upon a number of factors as well as the temperature of formation. For this and other reasons there is ground for doubt as to the validity of the relationship postulated above. To date a large number of readings have been made with the pyrite geothermometer which have been recorded in terms of the calibration of the instrument in degrees centigrade. So far most of the pyrite tested by this technique has been in association with gold ore. The values for the temperature of formation obtained in these tests appear to be reasonable and, in relation to geological problems, to vary in the right sense. Determinations on some specimens not in association with gold ore have given readings that appear to be much too high, taking into account the probable maximum temperature of the host rock. To sum up, although many determinations made with the. pyrite geothermometer appear to give reasonable values for the temperature of formation of the pyrite, there are at the same time other readings which seem anomalous. On the basis of an examination of available results of work with the pyrite geothermometer, two problems must be considered: 1-the validity of the calibration of the pyrite geothermometer; and 2-the nature of the distribution of the thermo-electric potentials of pyrite in relation to the specific problems that have been examined. In this paper the academic problem relating to the validity of the calibration of the pyrite geothermometer will not be discussed. Instead, the variations of thermo-electric potential of pyrite in association with gold veins will be discussed with regard to specific examinations. The first of these two examinations deals with the distribution of thermo-electric potentials of pyrite in association with a gold vein and was carried out in the McIntyre Porcupine Mine, Schumacher, Ont., in the summer of 1949 as part of a study with this technique. The second problem deals with variations of thermo-electric potential of pyrite in gold ore specimens from all over the world. The specimens used in this study were part of the private collection of Frank Ebbutt, geologist for Howe Sound Exploration Co. Results of Detailed and Reconnaissance Studies In discussion of the results of determinations made in these two studies the values of thermo-electric potential in millivolts will be used. It will be noted that in some of the diagrams the determinations are recorded in terms of pyrite geothermometer temperatures. Fig. 1 is a calibration chart relating, pyrite geothermometer temperatures and thermo-electric potentials. A full discussion of the technique is given in the original paper by F. G. Smith.&apos; Briefly, the determinations are made by placing two stainless steel probes, one hot and the other cold, against the surface of the pyrite crystal being tested. The thermo-electric potential that is developed is read with a null-point potentiometer that is calibrated in what

Jan 1, 1952

By Ernest F. Burchard

The Pao deposits of iron ore are in the State of Bolivar, Venezuela, near Upata, about 30 miles south of the Orinoco River and 90 miles east of Ciudad Bolivar. They were discovered 4 or 5 years ago and have not yet been developed to the stage of mining. In March-April, 1929, the writer devoted a week to the examination of these deposits. The maps, drill records and chemical analyses presented herewith were derived from original sources, and the field photographs were made by the writer. The petrographic and metallographic data are from notes by C. S. Ross and M. N. Short, of the U. S. Geological Survey, who have kindly collaborated in these special phases of the study. The Iron Obebodies Topography and Accessibility The deposits are in a region of low mountains representing northern outliers of the Guayanan Highlands. These mountains reach altitudes of 1800 to more than 2000 ft. above sea level, as determined by aneroid barometer. The iron ore is found on mountain crests that reach altitudes of 1915 to 1930 ft., and may be followed down precipitous slopes for 200 • to 300 ft. or more. The greatest vertical range in outcrop is nearly 400 ft., and drilling has indicated that the ore extends to this depth below the surface in one place, at least. The superior hardness of the iron ore accounts for the preservation of the local mountain crests with the intermediate valleys eroded in softer granitic rock. The deposits of iron ore are reached by a private road for automobiles branching northeast from the Ciudad Bolivar-Upata road, a distance of about 12 miles. This road was used in 1928-29 by trucks for transportation of food and camp supplies, gasoline, drilling equipment, etc., but was not suitable for the transportation of iron ore. Between Ciudad Bolivar and the iron-ore area the western two-thirds of the automobile road passes through nearly level, open country known as the savanna, largely used for grazing cattle. About 96 km. (60 miles) east of Ciudad Bolivar at

Jan 1, 1931

By Jamie Deuel

The a ad on Connection" For the purpose of this paper, we will concentrate on the ubquitous radon gas as the principle, low-level radiation effect from uranium tailings piles. Standards are also proposed for gamma radiations but, by most accounts, this is much less of a low level problem than is radon. I am also aware of some just completed research at Oak Ridge National Laboratories that suggest polonium may be a major concern in tailings, but those data are preliminary at this time. What is radon gas? In the first place it is not a gas in the accepted sense in that it has no driving pressure head. It might prove a more convenient description to call it radon vapor. Radon vapor, then, is 7-1/2 times heavier than air. Radiologically, it is an alpha emitter which means it spontaneously gives off high ionizing potential but low penetrating power particles. In fact, the alpha particle has such low penetrating power that this sheet of paper will completely shield a person. The problem, though, is breathing the radon decay products, called radon daughters. If radon daughter products are ingested into the lungs, their alpha emissions may cause cancer. The principle carcinoma associated with breathing radon, or more basically, associated with radiological effects is oat cell car- cinoma of the undifferentiated mall cell type. Radon has a 3.8 day half life which means in less than four days half of its initial radioactivity has decayed away. In less than a month it essentially becomes inert or non-radioactive. The Tailings Situation The NRC, in its April 1979 Generic Environmental Impact Statement

Jan 1, 1983

By William A. Johnson

The mathematical analysis of diffusion curves in solid metals is carried out ordinarily by analogy with the flow of heat in a continuous medium and no account is taken of the fact that the materials involved are composed of discrete particles that move discrete distances at irregular intervals. It is possible to treat the problem on the basis of simple assumed atomic mechanisms, in which case, because of the small scale of the elementary process compared to the gross effects observed experimentally, the two procedures lead to the same expression for the variation of concentration with distance. Thus, for engineering purposes, the usual methods are quite satisfactory. If, on the other hand, our purpose is to go beyond the mere collection of data, however desirable this may be, it is necessary to recognize and understand the factors that are of fundamental importance. One factor that has not hitherto been considered when dealing with solid metals is the difference in atomic weights of the isotopes of a single metal. While all the atoms of a given element are alike chemically, their weights may vary by a small but significant amount, and atoms of different weights may have different diffusion rates. With gases this variation in isotopic weight produces a change in the rate of diffusion by a factor inversely proportional to the square root of mass. While, except for the lightest gases, this is not a large effect, it is, for example, sufficient to permit a considerable concentration of one isotope at the expense of others. If metals exhibit a similar phenomenon, some modification of the analysis of the diffusion process will be required, since the different isotopes of a given metal will have different probabilities of moving and the heat-flow analogy will contain a fundamental error. This situation cannot be rectified by using a diffusion coefficient based on the average probability of moving, and it can be shown that even when the diffusion coefficient is independent of composition, the diffusion curve will not agree with the simple theory except in the rare cases where only one isotope exists; e.g., gold. If, however, the mass effect in the solid state were no larger than in the gaseous, the errors arising therefrom in the analysis of ordinary diffusion curves would be quite negligible. Nevertheless, our desire to obtain all possible information concerning the details of the diffusion process, and the possibility of diffusion in the solid state as a means for separating isotopes are cogent reasons for undertaking an experimental study to determine whether isotopes of different masses diffuse at different rates. Experimental Procedure If isotopes of different masses diffuse at different rates, the ratio of the concentration of one relative to another will vary with the distance from the diffusion inter-

Jan 1, 1946

By William A. Johnson

The mathematical analysis of diffusion curves in solid metals is carried out ordinarily by analogy with the flow of heat in a continuous medium and no account is taken of the fact that the materials involved are composed of discrete particles that move discrete distances at irregular intervals. It is possible to treat the problem on the basis of simple assumed atomic mechanisms, in which case, because of the small scale of the elementary process compared to the gross effects observed experimentally, the two procedures lead to the same expression for the variation of concentration with distance. Thus, for engineering purposes, the usual methods are quite satisfactory. If, on the other hand, our purpose is to go beyond the mere collection of data, however desirable this may be, it is necessary to recognize and understand the factors that are of fundamental importance. One factor that has not hitherto been considered when dealing with solid metals is the difference in atomic weights of the isotopes of a single metal. While all the atoms of a given element are alike chemically, their weights may vary by a small but significant amount, and atoms of different weights may have different diffusion rates. With gases this variation in isotopic weight produces a change in the rate of diffusion by a factor inversely proportional to the square root of mass. While, except for the lightest gases, this is not a large effect, it is, for example, sufficient to permit a considerable concentration of one isotope at the expense of others. If metals exhibit a similar phenomenon, some modification of the analysis of the diffusion process will be required, since the different isotopes of a given metal will have different probabilities of moving and the heat-flow analogy will contain a fundamental error. This situation cannot be rectified by using a diffusion coefficient based on the average probability of moving, and it can be shown that even when the diffusion coefficient is independent of composition, the diffusion curve will not agree with the simple theory except in the rare cases where only one isotope exists; e.g., gold. If, however, the mass effect in the solid state were no larger than in the gaseous, the errors arising therefrom in the analysis of ordinary diffusion curves would be quite negligible. Nevertheless, our desire to obtain all possible information concerning the details of the diffusion process, and the possibility of diffusion in the solid state as a means for separating isotopes are cogent reasons for undertaking an experimental study to determine whether isotopes of different masses diffuse at different rates. Experimental Procedure If isotopes of different masses diffuse at different rates, the ratio of the concentration of one relative to another will vary with the distance from the diffusion inter-

Jan 1, 1946