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By Arthur L. Flagg

The Elk City mining district of Idaho occupies a position near the geographical center of Idaho county, a region of moderate elevation in the western foot-hills of the Bitter Root mountains. The district comprises an area of approximately 350 Sq. miles, bounded on the west by the Newsome district and on the south by the Dixie and Oro Grande districts. There are no mining districts to the north or east. Elk City, the principal town and the seat of the mining office for the district, is situated in a hydrographical basin surrounded by low hills. The elevation is 4,200 ft. above sea-level. Through this basin flow Elk Creek, Red river, and American river, which unite west of town to form the south fork of the Clearwater. The one township is set out from the Bitter Root Forest Reserve. Though a railroad starting from the Stites terminus of the Clearwater Short Line of the Northern Pacific railroad has been under consideration for some years, the camp is yet without railroad facilities. The projected road would follow the south fork of the Clearwater on easy grades, but would be very expensive to build and maintain. While such a road would greatly benefit those who are now operating in the camp, and in a sligh degree stimulate interest in its possibilities, there is hardly business enough to warrant its construction. At present all supplies and equipment are hauled in by wagon from Stites, a distance of 58 miles, over a wagon road constructed by the State in 1904, following in the main the old Nez Perce trail. While this is not a bad road, it is not all that might be desired. Starting at Stites at an elevation of 1,327 feet above sea-level, the road runs through low hills to Clearwater, a distance of 10 miles. In the next 16 miles the climb is steady until the Mountain House is reached, which is near the summit of Mount Pisgah. This is the highest point passed on the road, having an elevation of 6,500 ft. From the

Jan 1, 1914

By W. F. Netzeband

THE zinc-lead mines of the Eagle-Picher Lead Co. are situated in the Tri-state district of Oklahoma-Missouri-Kansas. The company is operating, at the present time, seven mines in the brecciated deposits of the Picher, Okla., camp; two in the water-course ground of the Treece, Kans., camp; two in the open, boulder ground of the Crestline, Kans., camp; and one in the sheet ground of the Pierce City, Mo., camp. The accompanying map (Fig. 1) shows the relation of the rich narrow runs to the other ore-bodies of the district. The runs are designated by cross-hatching so as to distinguish them from narrow drifts that have been driven as prospect drifts or haulage drifts. Figs. 2, 3 and 4 are cross-sections showing the type of formation encountered in the operation of the drills. The Picher camp is in the brecciated type of deposit with some water-course ground encountered, usually near the edge of the deposit. These deposits are flat and fairly uniform so that they can be mined systematically. However, scattered between these deposits are narrow runs that are usually very rich. Up to the present time, most of the prospecting has been done from the surface with churn drills, supplemented with some prospect drifts in the ground, once the mine is opened up. Prospect drifts are expensive, do not give much information except the presence or absence of ore and are therefore not used to any great extent. In the early days of the camp only the larger deposits were found and mined, with an occasional narrow run which was drilled out more or less by sheer luck. Later, more of these narrow rich runs were found and mined, until today many of the properties that were formerly considered worked out are being leased and re-drilled. It is very evident that many of these narrow runs, which are often only 20 ft. wide, can easily be missed by drilling from the surface unless very close drilling is practiced. This, of course, becomes very expensive as there are from 150 to 250 ft. of

Jan 11, 1926

By G. A. Moore, D. W. Williams, C. E. Sims

During the past several years the steel casting industry has made studies of heavy castings in which the test bar has been taken from heavy sections rather than from attached or separately cast coupons. It has been noted that the ductility properties of these heavy sections are often lower than those normally expected. Such lowered ductility is usually accompanied by a spotty test bar fracture and the ductility values often can be greatly improved if a low-temperature aging treatment is given to the casting. A loss of ductility of this type is considered "abnormal," since it is not accompanied by an increase of tensile strength or hardness, and "temporary" when the ductility can be restored by aging, The cure of such an abnormal condition represents a real improvement in the quality of the steel. Some hundreds of previous investigations, largely qualitative in nature, have established beyond reasonable doubt that hydrogen is normally present in newly manufactured steel and that this gas, in small amounts, can cause a temporary ab- normal loss of ductility. The commonly observed association of high gas content and low ductility has given strong evidence for the presumption that hydrogen, possibly assisted by other gases, is the primary cause of the low ductility observed. Accordingly, the Steel Founders' Society of America has, since Nov. I, 1944, sponsored investigations at Battelle Memorial Institute whose primary objective is to obtain quantitative information on the relation of the amount of hydrogen and nitrogen in steel, together with associated methods of steelmaking and treatment, to low-ductility effects and porosity. In order that these investigations might proceed on a quantitative basis, hydrogen analyses of a precision considerably higher than any previously reported in the literature were necessary. 'The method chosen was selected entirely on the basis that it had the highest probability of freedom from uncontrollable errors and will be described in detail in another publication.' Briefly, the method used consisted of the hot extraction of solid pieces of steel weighing from 45 to 50 g in a highly evacuated quartz tube maintained at 1050°C (1925°F) for a period of approximately 40 hr. The greatest precautions were taken to eliminate blanks and insure a sound gas-collection system. vacuum and temperature conditions were maintained automatically. Mercury-filled risers were used for the introduction of samples in order that the System could be degassed thoroughly in

Jan 1, 1949

By C. E. Sims, G. A. Moore, D. W. Williams

During the past several years the steel casting industry has made studies of heavy castings in which the test bar has been taken from heavy sections rather than from attached or separately cast coupons. It has been noted that the ductility properties of these heavy sections are often lower than those normally expected. Such lowered ductility is usually accompanied by a spotty test bar fracture and the ductility values often can be greatly improved if a low-temperature aging treatment is given to the casting. A loss of ductility of this type is considered "abnormal," since it is not accompanied by an increase of tensile strength or hardness, and "temporary" when the ductility can be restored by aging, The cure of such an abnormal condition represents a real improvement in the quality of the steel. Some hundreds of previous investigations, largely qualitative in nature, have established beyond reasonable doubt that hydrogen is normally present in newly manufactured steel and that this gas, in small amounts, can cause a temporary ab- normal loss of ductility. The commonly observed association of high gas content and low ductility has given strong evidence for the presumption that hydrogen, possibly assisted by other gases, is the primary cause of the low ductility observed. Accordingly, the Steel Founders' Society of America has, since Nov. I, 1944, sponsored investigations at Battelle Memorial Institute whose primary objective is to obtain quantitative information on the relation of the amount of hydrogen and nitrogen in steel, together with associated methods of steelmaking and treatment, to low-ductility effects and porosity. In order that these investigations might proceed on a quantitative basis, hydrogen analyses of a precision considerably higher than any previously reported in the literature were necessary. 'The method chosen was selected entirely on the basis that it had the highest probability of freedom from uncontrollable errors and will be described in detail in another publication.' Briefly, the method used consisted of the hot extraction of solid pieces of steel weighing from 45 to 50 g in a highly evacuated quartz tube maintained at 1050°C (1925°F) for a period of approximately 40 hr. The greatest precautions were taken to eliminate blanks and insure a sound gas-collection system. vacuum and temperature conditions were maintained automatically. Mercury-filled risers were used for the introduction of samples in order that the System could be degassed thoroughly in

Jan 1, 1949

This volume summarizes characteristics and the geological setting of porphyry copper deposits of the Western Hemisphere. Grouped by characteristics, porphyry copper deposits are described in six regions: Andean orogen, Appalachian orogen, Alaska, northern Cordilleran orogen, southern Cordilleran orogen, and the Caribbean. Each region has its own peculiarities of geologic setting, and those deposit characteristics that may be projected from one chapter to another will be used in reaching the conclusions from which to draw genetic models for porphyry copper deposits. The term porphyry in this volume denotes a type of ore deposit, rather than a rock classification. The classification of intrusive igneous rocks used in this volume is shown in Figs. 36a and 42 (pp. 103, 130). Some modern classifications suggest mineral-ratio definitions other than those used in this volume; however, most literature references cited are based on the classification shown in Figs. 36a and 42. The reader should be aware, therefore, that quartz monzonite in this volume contains from 35% to 65% potassuim feldspar and at least 10% quartz. A term used in this volume is defined where introduced within the context of a specific chapter. Distensional tectonic conditions are used in the sense of Cady (1972) in the Appalachian orogen, for example. Porphyry copper deposits are defined as large bodies of mineralized rock, usually including a porphyritic intrusive phase, that have copper sulfide minerals disseminated through them. The definition has no commercial connotation and is used strictly in a noneconomic sense to encompass the spectrum of copper mineralization associated with these deposits. Terms commonly accepted in the literature are not defined. Porphyry molybdenum and porphyry copper deposits commonly are distinguished by most economic geologists. The basis for the separation is summarized in one chapter of this volume. To permit the reader to more easily peruse the bibliography for any particular region, references will be found at the end of each chapter. The bibliography is not intended to be complete, but is designed to provide adequate minimum coverage for descriptions of deposits in the chapter concerned. Each entry is properly referenced in the text of that chapter to facilitate the reader's research into any particular topic. This volume is written from the point of view of the exploration geologist whose task it is to evaluate the structural, petrographic, mineralogic, and metallogenic characteristics of a porphyry copper deposit. The goal of the evaluation is to determine if, and where, concentrations of metals may exist in an igneous- hydrothermal system that includes the most complex set of geologic factors found in any of the many types of ore deposits. The successful porphyry copper geologist is simultaneously a petrographer, geochemist, structural geologist, and mineralogist. Some porphyry copper deposits have developed in volcanic arcs underlain by a Benioff seismic zone with a trench paralleling the arc. The most convincing example of a deposit known to have developed in an environment where subduction is an active process is the 3.3 m.y. (million years) old Dry Creek occurrence in the Aleutian arc (this volume). On the other hand, the younger deposits in the Cascades appear to have formed in a volcanic arc lacking both the Benioff zone and the offshore trench. Subduction is not widely accepted as an active mechanism for the period when the younger Cascade deposits formed. Subduction has also been questioned for deposits formed at a great distance from a plate boundary (e.g., Bingham). Regardless of the pros and cons regarding subduction, most deposits are associated with regional faults. Strike-slip

Jan 1, 1978

During the nineteen months in which our country was actively engaged in the war, the United States Shipping Board Emergency Fleet Corpn. expanded the shipbuilding capacity of the United States from an unimportant position among the world's producers of ocean-going tonnage to first place. At the same time it increased the overseas merchant fleet of the United States from a negligible quantity to second place. The shipbuilding program has been greatly reduced since the signing of the armistice. There have been suspended or canceled contracts for 754 ships aggregating 3,797,825 deadweight tons, which would have cost $797,564,276 to complete. The cost of canceling these contracts will be about $202,853,456, and the saving effected by cancelations will approximate $594,710,820.

Jan 7, 1919

By Benjamin Petkof

The mineral mica, which has been known to man since ancient times, has played an impor¬tant role in the development of our modern industry. In the latter part of the 19th century sheet mica began finding use as a dielectric insulating material in the newly developing electrical industry. Later, when modern elec¬tronics began to develop, it became a vital insulating and dielectric material for use in electronic equipment. Both the electrical and electronic industries were greatly dependent on some form of natural mica. The manufacture of electric motors of varying sizes, electronic tubes, and other electronic items was dependent on an adequate supply of sheet mica. During World War II this material was so vital to national defense that special efforts were made to mine it in the United States as well as to obtain it from overseas mica-producing areas. However, advancing technology has successfully begun the progressive development of man-made mica-based and non-mica-based materials that can replace mica for many uses. In addition, developing technology has dictated changes that have made sheet mica unnecessary for some uses. As the demand for sheet mica declined, the demand for scrap and flake mica has continued to increase. In fact, today the domestic production and use of scrap and flake mica far outshadows the necessity for good¬quality sheet mica in this country. Historically the United States has always been dependent on foreign sources of material for good-quality sheet mica and imports practically its entire requirement. In the case of scrap and flake mica, the United States is the dominant world producer and consumer. End Uses Sheet mica (Chowdhury, 1941; Rajgarhia, 1951; Skow, 1962) is available in many com¬mercial forms, but these forms can be broadly classified into manufactured and unmanufac¬tured mica. Manufactured mica consists of mica that has been shaped, punched, or other¬wise processed into some form, suitable for a particular end use. Unmanufactured mica con¬sists of partially hand-trimmed or processed material that has not been prepared for any particular end use. Unmanufactured mica is broken into two commercial classes consisting of sheet mica and scrap and flake mica. These classes of mica differ greatly in their ultimate end uses and marketed forms. Sheet muscovite mica can be classified by color, degree of prep¬aration of the crude material, thickness, size, visual appearance, and electrical quality. In addition, phlogopite mica is also classified by its thermal stability. Scrap and flake mica consist of mine, trimming shop, and factory scrap that occurs as remnants from mining, processing, and manufacturing operations, and small particle size mica that is available from the beneficiation of pegmatites, clays, schists, or other mica-rich host rock. The end uses for sheet mica vary so greatly from those of scrap and flake mica that it is necessary to discuss them separately. Sheet Mica Sheet mica consists of relatively flat sheets of material which have been mined as naturally occurring books or runs of mica. These sheets are hand-trimmed to remove any imperfections and are punched or stamped into specified shapes for industrial use. Sheet mica can be further processed and is described or specified as block, film, or splittings based on thickness. Block mica is not less than 0.007 in. thick with a minimum usable cross-sectional area of 1 sq in. Film mica is split from the better quali¬ties of block mica to specified thickness groups ranging from 0.0012 to 0.004 in. Splittings are sheets of mica with a maximum thickness of 0.0012 in. and a minimum usable area of 0.75 in. Other small sized, lower quality block mica

Jan 1, 1975

By L. E. Wemple

Previous to 1915, zinc refining had not become a general practice among the zinc smelters in the United States. Such refining as had been carried on was confined chiefly to remelting very high-leaded zinc, such as third-draw metal from the retort furnaces, and slab dross, and hard spelter from galvanizing pots. In this remelting operation, the lead and iron were settled out and the refined spelter obtained graded fifth class, ie., Prime Western. Owing to the presence of lead in most zinc ores, the bulk of the spelter produced by direct smelting is of this Prime Western grade. Careful selection of ores of low lead content gave purer grades of spelter, z.e., Brass Special and Intermediate; and smelters which could secure ores carrying practically no lead produced high-grade spelter. Thus, in general, the grade of spelter produced by any smelter was predetermined by the purity of the ore it could obtain. The needs of the warring nations of Europe for enormous quantities of cartridge and other high-grade brass resulted in such a demand for the purer grades of spelter that the available supply of lead-free and low-lead ores could not produce the quantity required. Prime Western grades went begging, so to speak, while high grades sold at times from 5 to 15 c. per pound over the Prime Western market. The great demand, coupled with the wide market margin, which permitted the inherent costs and losses, resulted in the conversion of the lower grades into higher grades by processes of refining. These conditions also accentuated the development and size of the electrolytic plants, which were being worked out at the time this increased demand for pure grade of metal occurred. The electrolytic process, where available, produces a higher grade of spelter from impure ores than does the fire process; a large portion of those impurities in the ore, which by the distillation process would be carried into the spelter, are removed in the leaching of the ores and the purification of the solutions. The refining process, adopted at a number of smelters for the purpose of converting low-grade spelter into grades suitable for bras4 was that of redistillation.

Jan 1, 1918

At the Second Pan-American Scientific Congress, meeting in Washington, D. C., from Dec. 27, 1915 to Jan. 8, 1916, the following special topics will be discussed in each of the four sub-sections of Section VII, of which Hennen Jennings is Chairman: A. Mining.-The mining law of each country and the changes that may be made to aid the development of mineral resources. History of the mining industry in each country with reference to the beginnings of that industry. The development of the Patio process. Bibliography of mining. B. Metallurgy.-Present methods of concentrating ores and the development of concentration methods. International relations in the exchange of ores and metals. Bibliography of metallurgy. A. and B. Mining and Metallurgy.-Development of hydro-electric power for mining and metallurgy, the amount probably available, and specific benefits from its utilization.

Jan 1, 1916

C. Q. Payne, New York City: Prof. Blake's inference that magnetic separation may be successfully employed upon smithsonite and iron oxide, after a preliminary roasting, is confirmed by the fact that this separation has been carried on with entire success for over a year at the works of the Wythe Lead and Zinc Mine Co., Austinville, Va. The ore mined on this property is a mixture consisting chiefly of galenite, smithsonite and limonite. The crude material is crushed, screened and washed in log washers for the removal of clay, and then jigged for the separation of the galenite. The zinc-and iron-ores are then roasted in reverberatory furnaces, being turned and moved towards the bridge-end of the hearth by manual labor. The roasted material contains from 20 to 26 per cent. of metallic iron. The slight difference in the specific gravities and the friable condition of the ores after roasting prevent the separation of the oxides by means of jigging. It was therefore the practice, previous to the use of magnetic separation, to charge the roasted material directly into the retorts of the zinc-furnaces. The rapid cutting of the retorts under this practice proved a serious inconvenience and expense. In the spring of 1892, the writer built for the Wythe Lead and Zino Mine Co. a magnetic separator which embodied several novel features and which was designed to treat the roasted zinc- and ironoxides. This separator has proved entirely successful for the purpose for which it was designed. During the first nine months of its operation, 1415 tons of 2240 pounds of roasted material were passed through the separator, producing about 675 tons of heads carrying from 50 to 55 per cent, of metallic iron, which are sold to a neighboring blast-furnace. The tailings, which contain the zinc, carry from 4 to 6 per cent. of metallic iron. For magnetizing the iron-ore previous to separating it from the zinc-ore, no change whatever mas made in the form of the reverberatory furnace previously employed. It was found that, by charging near the bridge-end of the hearth, toward the end of the roast-

Jan 1, 1894

By C. B. Jordan

LAVES and Wallbaum' have described TiRu and TiOs as having the same structure as TiFe; they had previously described the latter compound as having the CsCl structure. On the other hand, a careful investigation of the structure of TiFe by Duwez and Taylor- ailed to reveal the ordered CsCl structure, finding instead a random arrangement of titanium and iron atoms on the points of a body-centered-cubic space lattice. Consequently, it is not clear whether Laves and Wallbaum proposed the ordered or the disordered structure for TiRu and TiOs. In order to settle this question as to the structural type and to obtain values of the lattice para- meters (thereby completely determining the structures), the present investigation was undertaken. Samples having the compositions TiRu and TiOs were weighed out accurately from iodide titanium supplied by the New Jersey Zinc Co., ruthenium powder from Goldsmith Brothers Smelting & Refining Co., and osmium powder from Wildberg Brothers Smelting & Refining Co. No analysis was made of any of these metals. According to the respective analyses of the suppliers, total impurities amount to less than 0.03 pct in the titanium and to less than 0.5 pct in the osmium. The purity of the ruthenium is not known. The alloys were prepared by arc melting in a furnace of the type described by Schramm, Gordon, and Kaufmann.9 pecimens for X-ray diffraction were obtained by crushing the ingots and passing the resulting powders through a 200 mesh screen. Diffraction patterns were made with a powder

Jan 1, 1956

By Leland Wemple

PREVIOUS to 1915, zinc refining had not become a general practice among the zinc smelters in the United States. Such refining as had been carried on was confined chiefly to remelting very high-leaded zinc, such as third-draw metal from the retort furnaces, and slab dross, and hard spelter from galvanizing pots. In this remelting operation, the lead and iron were settled out and the refined spelter obtained graded fifth class, i.e., Prime Western. Owing to the presence of lead in most zinc ores, the bulk of the spelter produced by direct smelting is of this Prime Western grade. Careful selection of ores of low lead content gave purer grades of spelter, i.e., Brass Special and Intermediate; and smelters which could secure ores carrying practically no lead produced high-grade spelter. Thus, in general, the grade of spelter produced by any smelter was pre-determined by the purity of the ore it could obtain. The needs of the warring nations of Europe for enormous quantities of cartridge and other high-grade brass resulted in such a demand for the purer grades of spelter that the available supply of lead-free and low-lead ores could not produce the quantity required. Prime Western grades went begging, so to speak, while high grades sold at times from 5 to 15 c. per pound over the Prime Western market. The great demand, coupled with the wide market margin, which permitted the inherent costs and losses, resulted in the conversion of the lower grades into higher grades by processes of refining. These conditions also accentuated the development and size of the electrolytic plants, which were being worked out at the time this increased demand for pure grade of metal occurred. The electrolytic process, where available, produces a higher grade of spelter from impure ores than does the fire process; a large portion of those impurities in the ore, which by the distillation process would be carried into the spelter, are removed in the leaching of the ores and the purification of the solutions. The refining process, adopted at a number of smelters for the purpose of converting low-grade spelter into "grades suitable for brash was that of redistillation.

Jan 11, 1917

By Robert Henry Bradford

This investigation was undertaken at the suggestion of Prof. Henry M. Howe, of the Department of Metallurgy, Columbia University, who, in a letter to the author, dated October 23, 1900, wrote as follows, suggesting the subject of this dissertation : "The extraction of silver from copper mattes by either the Ziervogel or the Augustin process depends upon converting the silver into silver sulphate by means of the sulphuric anhydride evolved from the decomposition of ferrous sulphate and cupric sulphate, which are formed during the roasting operation itself from the iron and copper sulphides present. "It occurred to me, some time prior to the autumn of 1897, that these processes might be made much easier by adding to them, at the proper stage, ferrous or cupric sulphate, or both, in the form of green or blue vitriol. That is, instead of having to rely solely on our ability to generate these sulphates in this very delicate roasting operation, my idea was that we could add a small quantity of already-prepared sulphate at the proper state of roasting, viz., at or before the period when the solphatizing of the silver occurs. The comprehensive audit of the accounts of a mining company is extremely important in its relations to the legal situation and obligations of the corporation, the personal liability of the directors, and the interests of the investing public. A consideration of the subject as affecting the professional duties and fixing the responsibility of a mining engineer engaged in the expert examination of a mine or in charge of mining operations, is equally important, though this phase of the question is not often presented systematically.

Jan 1, 1903

By Oliver C. Ralston, Foster Fraas

Electrostatic methods of separation are used only when some peculiar advantage is gained. Such cases are minerals that are not separable by differences in specific gravity or magnetic response and that are desired in particles as large as 10-mesh, a size on which flotation separation is inefficient. This paper covers several separations of this type and others. It includes studies in the electrostatic behavior of kyanite, sillimanite, and zircon, simple silicates that cannot be called either acid or basic but are more nearly neutral. Kyanite and sillimanite are both desired in 10-mesh size and are difficult to bene-ficiate from low-grade ores to give that type of concentrate. A separation of garnet from diopside was studied because this mixture had been removed from a wollas-tonite product by drying and magnetic separation, and no special or extra-preparation for electrostatic separation was necessary. The Separator The separator used in these tests is of the nonhomogeneous field type shown in Fig Ia. It consists of a 11.4-cm-diam rotating metal roll 2 at ground potential over which the dry mixture of minerals is fed. The roll serves as one electrode of the separating field, and the other electrode is that of 3, a smaller 5-cm-diam rotating metal cylinder which is held at a high direct-current potential. In this paper the term "electrode" will be confined to the electrode at 3, roll 2 being designated only as "roll."

Jan 1, 1949

By Oliver C. Ralston, Foster Fraas

INTRODUCTION ELECTROSTATIC methods of separation are used only when some peculiar advantage is gained. Such cases are minerals that are not separable by differences in specific gravity or magnetic response and that are desired in particles as large as 10-mesh, a size on which flotation separation is inefficient. This paper covers several separations of this type and others. It includes studies in the electrostatic behavior of kyanite, sillimanite, and zircon, simple silicates that cannot be called either acid or basic but are more nearly neutral. Kyanite and sillimanite are both desired in 10-mesh size and are difficult to beneficiate from low-grade ores to give that type of concentrate. A separation of garnet from diopside was studied because this mixture had been removed from a wollastonite product by drying and magnetic separation, and no special or extra-preparation for electrostatic separation was necessary. THE SEPARATOR The separator used in these tests is of the nonhomogeneous field type shown in Fig I[a]. It consists of a 11.4-cm-diam rotating metal roll 2 at ground potential over which the dry mixture of minerals is fed. The roll serves as one electrode of the separating field, and the other electrode is that of 3, a smaller 5-cm-diam rotating metal cylinder which is held at a high direct-current potential. In this paper the term "electrode" will be confined to the electrode at 3, roll 2 being designated only as "roll." [ ]

Jan 1, 1947

Starting in 1940, national prize-paper contests for Student Associates and members of Student Chapters of the Institute have been conducted by a Sub- committee of the Committee on Student Relations Five cash prizes of $100 each may be given annually To be eligible for the national contest, a paper must have been the prize winner in a preliminary contest conducted by a Local Section of the Institute The money for the national prizes is drawn from the corpus of a special fund begun in 1940 by a contribution of $2,500 made by D C Jackling, and to which others have made substantial contributions since that time Contributions to the fund from members who are interested will be welcome since the original contributions are about exhausted A special committee, headed by Donald H McLaughlin, was appointed in 1952 to obtain further funds

Jan 1, 1952

By Paul B. Crawford, Bobby L. Landrum

Electrical model studies have been made of the effect of unsymmetrical vertical fractures on production cnpacity. The study war restricted to the case of two vertical fractures originating at the well and extending out into the reservoir for various distances and orientations. The ratio of the short fracture length to the long fracture length was varied from 0.1 to 1.0 in successive studies. The angle separating the two fractures was varied from 0 to 180 degrees. The most effective fractured patterns were obtained when the fractures were oriented 180 degrees. It was found that when the total fracture length was equal to 0.2 of the drainage radius, the increase in production capacity may vary from approximately 1.55 to 1.95. depending upon the ratio of the short fracture length to the long fracture length and the angle separating the two fractures. If the total fracture length were 0.5 of the drainape- radius. poroduction cavacitv., increases varving 1.95 to 2.65 were observed, depending on the angle between the fractures and the ratio of the .short fracture length to the long fracture length. The fractured well production capacity decreased aPproxin?ately I to 10 per cent as the angle separating the fractures was varied from 180 to 90 degrees. It was dependent on the particular fracture. The commercial application of reservoir fracturing techniques has caused an interest to be expressed in the effect of vertical and horizontal fractures on production capacities. Some data have indicated that substantially vertical fractures may be created in some reservoirs. It is believed that the fractures are possibly unsymmetrical, that is, one fracture may extend due north 100 ft and a second fracture on the opposite side of the well may extend south or southeast only 50 ft. The total fracture length, ratios of the lengths and angles of separation may vary considerably. For this reason variations in these factors were considered. The study was restricted to the case of two vertical fractures originating at the well and extending out into the reservoir. It is not known that such will occur in a reservoir, but the results may be of value in interpreting or studying fracturing applications. PROCEDURE An electrical model was used in this study of the effect of unsymmetrical vertical fractures on production capacity, A wooden tank 30 in. in diameter and approximately 2 in deep was coated with paraffin wax. A copper band was situated at the periphery and a single wire electrode was positioned at the center of the tank. The ratio of the reservoir radius divided by the

Jan 1, 1956

INTRODUCTION Porphyry copper deposits have been reported from the Caribbean area by Pease (1966), Cox, et al. (1973), Guild (1974), Kesler, et al. (1975), and others. This chapter summarizes the most widely known characteristics of those deposits. Only one deposit that conceivably can be classed as a porphyry copper occurrence is in production (Pueblo Viejo, Dominican Republic), but others are known whose tonnage and grade are of economic interest. Deposits in this province may be classified as copper-gold or copper-molybdenum types (Kesler, 1972), but deposits associated with quartz-rich plutons that have high Na2O:K2O and high gold:copper but low molybdenum: copper ratios dominate. Porphyry copper occurrences are reported in the literature from Puerto Rico, Haiti, the Dominican Republic, Jamaica, and Cuba. Only the porphyry copper deposits from Puerto Rico are extensively described in the literature; consequently the Caribbean porphyry copper province in general is not as well documented as the southern Cordilleran orogen. Because past published technical descriptions are incomplete, some data presented here are new to the literature. The Caribbean includes the island arcs between North and South America. Porphyry copper occurrences are known from the Greater Antilles, the generally east-west trending group of islands that lies south of North America. Fig. 48, therefore, only covers the Greater Antilles portion of the Caribbean. Porphyry copper deposits in this area are not described by the Lowell and Guilbert (1970) model in details of metallization (general paucity of molybdenum), alteration (scarcity of orthoclase), or petrography (preponderance of quartz diorite). Therefore, this model should be modified to include deposits associated with quartz-bearing plutons such as those found in the Caribbean. In the Meme deposit on Haiti ore occurs in skarn adjacent to the quartz diorite phase of a composite quartz monzonite-granodio-rite-quartz diorite pluton (Kesler, 1968). This deposit, with a K-Ar 66 m.y. date, is not included in Fig. 48 as a porphyry copper deposit because metallization is restricted largely to the intruded rocks. Although the intrusive rocks at the Meme deposit may contain sulfide near skarn contacts they are otherwise essentially unaltered. Porphyry molybdenum deposits as defined by Clarke (1972) have not been reported in the Caribbean area.

Jan 1, 1978

By G. Thodos, R. B. Grieves

A method has been developed for the accurate calculation of the cricondentberm and cricondenbar temperatures of multicomponent hydrocarbon mixtures of known composition. The mixtures may contain any number of components including paraffins and isoparaffins, olefins, acetylenes, naphthenes and aromatics. This approach is based upon the mole fraction of the low-boiling component in the mixture and graphically presents the ratios of the cricondentherm and cricondenbar temperatures to the pseudocritical temperature as {unctions of a boiling-point parameter. The only requirements are the critical temperature, normal boiling point and the approximate vapor pressure behavior of each component. For mixtures of more than two constituents a stepwise calculation procedure is necessary where the pseudocritical temperature is based upon the critical temperature of the pure low-boiling component and upon the actual cricondentherm or cricondenbar temperature of the mixture of all the remaining higher-boiling components. From an analysis of 22 binary systems (123 compositionsl, the average deviation of calculated cricondentherm temperatures from reported values is 0.87 per cent, based on degrees Rankine; and for 10 multicomponent mixtures containing from three to six components, the average deviation is 0.98 per cent. From an analysis of 18 binary systems (104 compositions) the average deviation of calculated cricondenbar temperatures from reported values is 0. 79 per cent; and for 15 multicomponent mixtures, 1.47 per cent. Equations, derived from the graphical relationships, are presented which enable rapid calculations for both binary and multicomponent systems. INTRODUCTION With the increasing tendency towards the use of high pressure processes, the need for an accurate method of calculation of the properties of a multicomponent hydrocarbon mixture in the critical region is becoming more essential. Critical region phase relations are also significant in gas condensate reservoirs, for which a knowledge of the fluid phase boundaries and regions of retrograde condensation make it possible to evaluate optimum operating conditions. The possibility of liquefaction in the underground structure may be established, and information on the feasibility of the use of repressurizing may be determined. A typical phase diagram for a multicomponent hydrocarbon mixture is presented as Fig. 1. This figure also shows the regions of retrograde behavior encountered by following lines AB and AC. If accurate methods of calculating the temperatures and pressures at the critical, cricondentherm (maximum temperature) and cricondenbar (maximum pressure) points of multicomponent hydrocarbon mixtures of known composition were available, it would be possible to estimate closely the entire phase diagram of any mixture. Several methods have been presented in the literature for the estimation of the critical temperatures and pressures of multicomponent mixtures containing all types of hydrocarbons and including the fixed gases.4-8,21 Considering the cricondentherm and cricondenbar points, the work is more limited. Etter and Kay5 have developed rather complex equations for

By W. B. Finkeldey, C. H. Mathewson, C. S. Trewin

This paper was prepared upon request as a contribution to a symposium covering the manufacture, properties, and uses of the important non-ferraus metals. In approaching a subject as broad as this, there is a natural desire to build up a comprehensive and finished production which shall constitute a dependable source of information on all questions properly belonging to this branch of metal technology. There are, however, a number of circumstances, apart from the mere routine of labor and thought involved, which operate rather effectively against the possibility of completing such .an ambitious program at the present time. First of all, as far as any public record of results is concerned, the commercial rolling, drawing, and forming of zinc with relation to changes of structure and properties—and this we consider to constitute the clement~ of metal technology—might as well be an unpractised art. We have never seen a published photomicrograph showing the structural characteristics of either hard or soft sheet or strip, although the structure of castings has been frequently described, and other coarse-grained structures resulting from hard-hammering and annealing have been reproduced. Thus, an author in this field must proceed to his task without much assistance from the literature, and the outcome can represent only a personal estimate of principles, facts, or findings, and not a summary or survey of progress in the entire field as determined by varied experience, practice, and settled opinion.

Jan 1, 1921