Search Documents

By R. B. Hoy, Stanley J. LeFond, K. Reckling

World production of natural diamonds prob¬ably exceeds 50,000,000 carats a year. The Republic of Zaire is the leading producer, with an output which is primarily industrial rather than gem grade. The USSR ranks second, and the Republic of South Africa third. Diamonds are also mined in South-West Africa, Angola, Ghana, Sierra Leone, and other African coun¬tries. In the western hemisphere, Brazil and Venezuela are the principal producers (Fig. 1). A very small output of diamonds is mined today in India, which was the first source of commercial production. In the U.S., efforts at commercial diamond mining have been con¬fined to a small area near Murfreesboro, Ark. The first diamond was found in a kimberlite pipe there in 1906. Small-scale trial mining has not, however, proved economical. Since diamonds were first discovered over 2000 years ago, only about 130 tons have been mined. In order to obtain 1 g (5 carats) of diamonds, it is necessary to remove and process approximately 25 tons of rock. Recovering this small percentage involves a combination of highly developed techniques in mining, quarrying, and earth-moving, and extremely sophisticated recovery processes. End Uses Diamonds are used for two unrelated end uses; gem diamonds are jewels of great beauty while industrial diamonds are essential ma¬terials of modern industry. Although imitation stones are substituted for the gem diamond, none of these matches its properties sufficiently well to offer real competition. Synthetic indus¬trial diamonds are now of a quality that per¬mits wide substitution in the fine-grained sizes. Gem Diamonds A diamond is a natural prism. It has the ability to bounce light rays (reflection), to bend them (refraction), and to break them into all colors of the rainbow (dispersion). This ability to "modify" light gives the diamond three characteristics for providing beauty. First is brilliance, the reflection of light back to the eye. Second is fire, dispersion of light into the colors of the spectrum. Third is scintillation, the "twinkling" that occurs when the diamond is moved (Bauer, 1969). The skill of the diamond cutter is required to unlock the brilliant, fiery beauty of a gem dia¬mond (Fisher, 1966). Diamond-cutting skills have gradually developed over the centuries. The first cutters, in India, learned how to grind one rough diamond against another to remove their "skins" and to give them various shapes. This revealed some fire and beauty, but little compared to that of the diamonds that are cut today. About 1475, a Flemish cutter named Van Gerquem discovered that diamond dust on an iron wheel would polish facets on a diamond to provide more brilliance and fire. Cutters continued to experiment with facets, and shortly before 1700 a Venetian cutter named Peruzzi developed the 58-facet brilliant cut. With the development of the science of optics, cutters have learned more about the behavior of light within the diamond. Early in the 20th century, they learned how to angle Peruzzi's

Jan 1, 1975

By AIME AIME

A LUSTY baby of the Institute, the Coal Division, showed that it had acquired a full set of teeth and was capable of man's work at the Division meeting at Fairmont, W. Va., on March 26 and 27. At this second of a series of field meetings, the first of which was held in Pittsburgh last fall, the industry in the East was represented from top to bottom and good humor and enthusiasm were the predominant notes. West Virginians are always good hosts and this meeting would have proved the statement to any inclined to doubt it. The spacious auditorium of the Fairmont Hotel was arranged for the technical sessions, the hotel being headquarters for the meeting. About a hundred and twenty-five representatives were registered and in attendance when Thomas G. Fear, chairman, opened the morning session at 10 o'clock Mr. Fear first introduced Howard Eavenson, vice-chairman of the morning program, who, as chairman of the Coal Division, had labored long and cheerfully to make the meeting successful. Mr. Eavenson talked briefly on what the organization was doing, pointing out that these field meetings were designed to bring the members into closer touch with the parent Institute and give the younger engineers in the field a better opportunity to participate in the work the Institute is doing. He congratulated the various committees for their work in promoting the meeting.

Jan 1, 1931

By J. N. Hummel

The methods of electrical prospecting, which employ contact electrodes to produce an electric field in the ground, furnish information concerning the constitution of the material beneath the surface, as indicated by the distortion of this artificially produced field and anomalies therein. To reveal the distortion of such field of known character, it is only necessary to measure qualitatively the direction of the field, using sensitive compensation methods. In such a case, the survey is relatively simple, and that is an important factor from a practical point of view. The distortion of the normal field thus determined permits an easy interpretation and gives approximate information as to the subsurface conditions, without the necessity of a thorough theoretical knowledge of the electrical field. The true field of application of the equipotential lines and search-coil methods, which are based on this principle of directional determination of the electrical field in the ground, is that of search for deposits of economic minerals for the mining industry, although they can also be used in solution of other problems; for example, in the determination of the strike of anisotropic beds. The distortion of the electric field as represented by the picture of equipotential lines or other measured curves is striking only when bodies having conductivities different from that of the country rock are embedded in the underground, or when the underground is anisotropic. It is obvious that methods based on such a simple principle and capable of solving directly many of the practical problems of mining geology have found a widespread application. However, these methods are unable to furnish any information as to the presence, depth and physical properties of layers in the underground, which have different conductivities, but are parallel, or only slightly inclined, to the surface. Where such conditions exist in the underground, the picture of the field

Jan 1, 1932

By W. B. Daly, A. S. Richardson

The application of artificial refrigeration, or air-conditioning, to the ventilation of deep, hot mines has long been a subject of interest to the operators of such properties. Artificial cooling of the air in theaters, railroad coaches, and various industrial plants has been so successful within recent years that it has been natural to assume that the adoption of similar methods would afford a ready solution to the difficult problem of mine ventilation. It should however, be obvious, that although there may be nothing technically impossible in the application of this process to mine ventilation there is a great economic distinction between the maintenance of a high standard of comfort for a large number of people in a relatively small space such as a theater and the cooling of air to improve working conditions for miners scattered throughout the extensive workings of a large mine. Many methods of air-conditioning have been considered by the management of the Anaconda Copper Mining Co. at various times, but until the development of the process to be described in this paper none has seemed economically practicable. The Ventilating Problem at Butte The main obstacle to satisfactory ventilation in the Butte mines is the normally high temperature of the granite country rock. In the present operating zone, rock temperatures as high as 120' F. have been noted, and in some parts of the district the rate of increase of temperature with depth has ranged as high as 3.5" F. per 100 ft. Other factors, such as the decay of mine timber and the oxidation of sulfide minerals in the ore bodies, contribute to raise the temperature of the air in the working places but, particularly in the development of the mines to greater depth, the naturally high temperature of the rock is of predominant importance. In few other places, probably, are the ordinary ventilating measures more hindered than at Butte. At an operating depth now exceeding 3000 ft., all of the air required for ventilation must pass through timbered shafts which, because of heavy ground, are of small size and offer great resistance to the flow of air. Shaft compartments are rarely more than 4.5 X 5 ft., and the shaft area open to the flow of air usually does not exceed 65 sq. ft.; in only two shafts is the area as great as 85 sq. feet.

Jan 1, 1934

THE composition and quality of finished steel depend upon selection and proportioning of the raw materials of the charge as well as upon control of furnace practice. This chapter deals only with the raw materials of the basic open-hearth process that are important in determining the composition of the steel or slag. They are the metallic charge, oxygen-bearing materials, fluxes, alloying and deoxidizing additions, and certain refractory materials used for maintenance of bottoms. Other refractories, which may affect the slag composition, are discussed in Chapter 3. Wide variations are possible in the type and composition of charged materials but certain limiting relations among the elements of the charge must be observed. Since the process consists essentially of refining by the oxidation of undesired dements, a balance must be established between the sources of oxygen and the elements in the charge that are subject to oxidation (see Chapters 2 and 7). For example, if it is desired to use a high ratio of blast-furnace hot metal to scrap, it is necessary to add an oxygen-bearing material such as ore or mill scale to eliminate the excess carbon and silicon that are present in the hot metal. An example of the opposite extreme is the use of a metallic charge composed entirely of steel scrap. With this type of charge, it is common practice to substitute burnt lime for limestone as a flux and to charge some carbonaceous material such as coke to avoid an excess of oxygen in relation to the elements of the charge that are subject to oxidation. Elements such as copper and nickel, which are not oxidized or eliminated by, any other reaction, may be introduced into the charge only to the extent to which they are permissible in the finished steel. An example of adjustment of the charge for elements of this type is found in the use of steel scrap high in copper. In this case, metallic components of the charge other than the scrap should be low in copper, or a sufficiently high ratio of pig iron to scrap should be charged to dilute the copper from the

Jan 1, 1951

By John T. Dickman, Ralph E. O’Dette

Chemical Abstracts Service (CAS) is in the process of evolving a computer-based information system which will process all of the material selected for abstracting in the area of chemistry and chemical engineering and its related fields such as the earth sciences and technologies. This system is already operational to some extent and is expected to be fully utilized by 1971. The objective of CAS is to make chemical and related information more readily available, more usable and more used. Chemical Abstracts handle some 5000 abstracts weekly from 13, 000 journals and patents from 25 nations. These cover all of the 80 CA subject sections which relate to chemistry and also extend into areas of interest to geologists, mineralogists, and mining engineers. In this way, CAS fulfills its objective of complete coverage of its major fields, informative abstracting, and indexing to maximum specificity. The concept of a computer-based information system is that of a single machine-language data base into which the results of intellectual analysis of the literature are entered and from which computer programs produce a variety of publications and services applicable to the needs of a wide range of users.

Jan 1, 1969

Discussion WEDNESDAY AFTERNOON, FEBRUARY 21, 1951 Ralph E. Grim presiding R. E. GRIM, CHAIRMAN-Has anyone a particularly fruitful point to make or question to ask on any of the papers that have been presented at the two sessions held on Monday and one held this morning? GENESIS OF ENDELLITE T. S. LOVERING-I think we are all a little bit embarrassed when we are asked if we have any particularly fruitful point for discussion; I just have a point. I believe that yesterday Bates said that he had found endellite in only hydrothermally altered rocks-he did not find it in sedimentary rocks-but this morning I heard Victor Allen say something about it as the normal product of weathering, and I am confused. My question concerns the genesis of endellite. I want to know whether endellite is found as a normal product of weathering. I understood from the paper by Bates that it was not a product of weathering and in the paper by Victor Allen* endellite was said to be a product of normal weathering. Did I misinterpret these two papers? T. F. BATES-I did not intend to state or imply that endellite is formed only under hydrothermal conditions. We have been studying the North Carolina deposits extensively and I feel that they illustrate very well the result of normal weathering processes acting on pegmatitic material. The resulting clay seems to be largely endellite or halloysite, almost to the exclusion of kaolinite. I may have misled you in the statement I made toward the end of my talk, to the effect that of all the kaolinic clays we have investigated with the electron microscope, we have not yet found halloysite or endellite in samples from clay deposits that are definitely sedimentary in origin. R. E. GRIM, CHAIRMAN-Professor Allen, have you anything to say on the matter of bauxite?

Jan 1, 1952

Trans. No. Place Date Vol. Page 1. Wilkes-Barre Pa......May.71 1 3 2. Bethlehem, Pa.........Aug., '71 I 10 3. Troy, N.Y............Nov..: 71 1 13 4. Philadelphia, Pa........Feb., 72.. 1 17 5. New York. N. Y.*......May, '72.. 1 20 6. Pittsburgh. Pa.........Oct..' 72.. 1 25 7. Boston, Mesa..........Feb., '73.. 1 28 8. Philadelhia, Pa.*......May, '73.. 2 3 9. Easton, is............Oct..' 73.. 2 7 10. New York, N. Y.......Feb..' 74 . . 2 11 11. St. Louie. Mo.*........May,' 74 . . 3 3 12. Hazleton, Pa...........Oct., '74.. 3 8 13. New Haven Conn......Feb., '75.. 3 15 14. Dover,N.J.*..........May, 75.. 4 3 15. Cleveland,O...........Oct. 75. 4 0 16. Washington D. C......Feb.'' 76.: 4 18 17. philadelphia, Pa.......June,: 76.. 5 3 18. Philadelphia Pa........Oct 76.. 5 19 19. New York, N. Y.......Feb: '77.. 5 27 20. Wilkes-Barre. Pa.*.....Mag :77.. 0 3 21. Amenia N. Y..........Oct. 77.. 6 10 22. Philadeiphia Pa........Feb.;' 78. . 6 18 23. Chattanooga' Term.*. . . May' 78. . 7 3 24. Lake George: N. Y....: Oct. 78. . 7 103 25. Baltimore, Md.*.......Feb:' 79.. 7 217 26. ~ittsburgi, Pa.........~a;' 79.. 6 3 27. Montreal, Canada......~ept.;' 79.. 8 121 28. New York, N. Y.*......Feb., '80.. 8 275 29. Lake Superior, Mich....Aug., '80. . 9 1 30. Philadelphia, Pa.*......Feb., '81. 9 275 31. Staunton, Va..........May, '81. .10 1 32. Harrisburg, Pa.........Oct.. '81..10 119 33. Washington, I). C.*....Feb., '82. . 10 226 34. Denver. Colo..........Aug.. '82. . ll 1 35. Boston. Mass.*.........Feb.. '83..11 217 38. Roanoke, Va...........June, '83.. 12 3 37. Troy, N. Y...........Oct.. '83. .12 175 38. Cincinnati. O.*.... Feb, '84..12 4 39. Chicago Ill............May, '84. . 13 1 40. philadelphia, Pa........Sept., '84. . 13 285 41. New York, N. Y.*......Feb., '85. . 13 586 42. Chattanooga, Tenn.....May, '85..14 1 43. Halifax, N. S..........Sept., '85.. 14 307 44. Pittsburgh, Pa.*........Feb.. '86 . . 14 587 45. Bethlehem. Pa.........May, '86 .. 15 Ixiii. 46. St. Louis, Mo..........Oct, 86.. 15 Ixx. 47. Scranton, Pa.*.........Feb.', '87. . 15 lxxvi 48. Utah and Montana.....July '87.. 16 xvii. 49. Duluth, Minn...........July' '87. -16 xxiv. 50. Boston. Mass.*.........Feb.: '88. . 16 xxviii. 51. Birmingham, Ala.......May, '88. .17 xix. 52. Buffalo N. Y..........Oct. '88.. 17 xxiv. 53. New york, N.Y........feb.' ;89 . . 17 xxxi. 54. Colorado..............June' 89 . . 18 xvii. 55. Ottawa, Canada........Oct., 89. . 18 xxiv. 56. Washington, I). C.*. . . Feb. 90. .18 xxx. 57. New York, N. Y........sept:, '93. .19 vii. 58. New York, N. Y.*......Feb. '91. . 19 xxv. 59. Cleveland, O.......... June, :91 . .a xvi. 60. Glen Summit, Pa.......Oct, 111. . 20 lxi. 61. Baltimore, Md.*.......Feb.: '92. .21 xix. 62. Plattsburg, N. Y.......June, '02. . 21 xxxiii. 03. Reading. Pa...........Oct., :92. .21 xliv. 64. Montreal. Canada*.....Feb. 93..21 65. Chicago, Ill............aug.: '93..22 XI. 66. Virginia Reach. Va.*. ...Feb., '04. .24 xwl. 67. Bridgeport Coon.......Oct., '94..24 xxx?. 08. Florida ...'............Mar., '95. .25 xix 69 Atlanta. Ga......... Oct 95. 25 xi 70. Pittsburgh. Pa.*........Feb., '96.. 26 xvii. Trans. No. Place Date Vol. Page 71. Colorado..............Sept. '96. .26 xxix. 72. Chicago, Ill............Feb.. "97.. 27 xvii. 73. Lake Superior..........July '97. .27 xxx. 74. Atlantic City, N. J.*. ..Feb.: :98. .28 xvii. 75. Buffalo N. Y..........Oct. 08. .28 XXXVI. 76. New York,N. Y.*......Feb.: '99. .29 xvii. 77. California.............Sept., ;99. . 29 xlix. 78. Washington, D. C.*.....Feb., 00. .30 xix. 79. Canada...............Aug.. '00. .30 xlv. 80. Richmond. Va.*........Feb.. '01. . 31 xix. 81. Mexico................Nov..'01.. 32 cxviii. 82. Philadelphia Pa. $......May, :02. . 33 xxxv. 83. New Haven, Conn......Oct.. 02.. 33 xlvii. 84. Albany N. Y.*........Feb '03. .34 xxiii. 85. New York, N. Y........Oct.': '03. .34 xi. 86. Atlantic City. N. J.*....Feb., '04. .35 XXIII. 87. Lake Superior..........Sept.'04. .35 dii. 88. Washington. D. C......May' '05. .36 xlii. 89. British Columbia.......July, '05. . 36 90. Bethlehem. Pa.........Feb. '06. .37 xli. 91. London, England.......July: '06. .37 xlviii. 92. New York, N. Y........April, '07. . 38 lii. 93. Toronto, Canada.......July. '07. .38 lix. 94. New York, N. Y........Feb., :08. .39 xli. 95. Chattanooga, Tenn.....Oct.. 08..39 xlviii. 06. New Haven Conn......Feb. '09. .40 xli. 97. Spokane,Wash.........Sept:.'09. .40 xlviii. 98. Pittsburgh, Pa.........Mar.,'10. .41 xxxviii. 99. Canal Zone............Nov.,'10. .41 dv. 100. Wilkes-Barre, Pa.......June. ' 11. . 42 xxxiv. 101. San Francisco, Cal......Oct.. '11..42 xliv. 102. New York. N. Y.*......Feb 12. .43 Ixxvii. 103. Cleveland, Ohio........0ct;' '12.. 44 wii. 104. New York, N. Y.*......Feb.. '13. .45 xv. 105. Butte, Mont...........Aug., '13. .46 ?' 108. New York, N. Y........Oct., 13..47 vii 107. New York. N. Y.*......Feb.. '14..48 xv. 108 Salt Lake City. Otah Aug. :l. 49 5: 109. Pittsburgh, Pa.........Oct., 14. .50 vii. 110. New York, N. Y.*......Feb., '15. .51 xvi. 111. San Francisco, Cal......Sept., '15. .52 xii. 112. New York,N. Y.*......Feb., '16..54 xvi. 1 Arizona...............Sept.,'l6. .55 VII 114. New York, N. Y.*......Feb., '17: .56 vii. 115. St. Louis, Mo..........Oct.. '17..57 vii. 116. NewYork,N. Y.*......Feb.. '18..59 xvii 117. Colorado.....:........Sept.,'18. .60 vii. 118. Milwaukee, Wis........Oct.. '18. .60 x:!: 119. NewYork,N. Y.*......Feb., '19..61 xi. 120. Chicago...............Sept.,' l9.. 62 VII. 121. New York, N. T.*......Feb., '20..63 ix. 122. Lake Superior District. .Aug., '20.. 66 ix. 123. New York, N. Y.*......Feb., '21. .66 xiii. 124. Wilkes-Barre, Pa...... Sept.. : 21.. 66 xix. 125. New York, N. Y.*......Feb., 22. .67 ix. 126. San Francisco. Cal......Sept.,:22. .68 xxix. 127. New York, N.Y.*.....Feb., 23. .69 xxix 128. Canada...............Aug., '23. .69 xxxv! 128.129. New York, N. Y.*......Feb., ;24. .70 xxxi. 130. Birmingham, Ala.......Oct. 24. .71 xxxiii 131. NewYork.N Y.*......Feb.: '25.. 71 xxxviii. 132. 131.Salt Lake City, Utah .. .Sept., '25. .73 xvi 133. New York, N. Y.*......Feb., '26. .73 xxii. 134. Pittsburgh Pa ....... Oct.. '26. .74 xv. 135. New York,' N. Y.*............Feb., '27. .75 x::: 135.136. NewYork,N. Y.*......Feb., '28..76 104 137 NewYork.N. Y.*......Feb., '29. .291 116 138.San FranciscoYork,N.Y. Cal..........Oct. 29..308 406 139. New York, N. Y.*...Feb., '30..30H 1321

Jan 1, 1930

By H. P. Wheeler

WHEN Germany invaded Poland in September, 1939, the only operating helium plant in the United States was that near Amarillo. Texas, supplied with helium-bearing natural gas from the near-by Cliffside gas field. Today the Bureau of Mines has five plants capable of producing more than 25 times the prewar helium output of the Amarillo plant. Two of the plants have received Army-Navy "E" flags for their part in the faraway "Battle of the Atlantic," where heliumfilled Navy blimps chased Adolf Hitler's submarines away from American shores. Meteorologists, watching balloons carried high into the stratosphere by helium, determined weather conditions that influenced the selection of D-day and dates for other military operation. Demand for helium doubled overnight when the Navy decided to expand its lighter-than-air activities; and as the blimp patrol proved effective, the helium demand became ever greater. A tribute to the success of the Bureau of Mines in meeting the demand for helium was paid by the late Secretary of the Navy, Frank Knox, in a letter to the Secretary of the Interior on April 10, 1944. Secretary Knox wrote, in part,

Jan 1, 1945

By WALTER B. JONES

IN ALABAMA there are three distinct groups of bauxite deposits, as follows: (1) Cambro-Ordovician contact with the principal-deposits located in Talla-dega, Calhoun, DeKalb, and Cherokee Counties, and in adjacent portions of the State of Georgia. (2) Midway-Nanafalia contact, with the principal deposits in Barbour and Henry Counties, and in adjacent portions of Georgia; also in North-eastern Mississippi. (3) Mississippian - Cretaceous contact, with a group of deposits centered around Margerum in Colbert County. For the purpose of more clearly describing bauxite mining in the state, past, present and possible future, these three groups will be described separately.

Jan 1, 1934

By Charles A. Morgan

The proms of mire drawing depends upon the property which certain metals possess, termed ductility, which is defined in Brande's Dictionary of Science as a property inconhequcnce of which metals may be drawn out at length wilhotit interrupting the continuity of their constituent parts. As ticfincd thy M. Tresca, it is the property of flowing when subjected to pressure, and ie termed by him the "flow of solids," in his paper, read before the AcaiXemy of Sciences in Paris, November, 1866 * In the simple language of the wire shop, it is that quality in certain metals that thcm to be drawn (or etretched) out througl~ a tapering hole in a metal block or die, the die being more dense and harder than the metal to be redud. It is a fact well known to tllose slrillet1 in the ai*, that to eu~xeed in drawing iron or steel wire, it is of' the utmost, importance to have tborough lubritatiun, as a lack of it woullii udu-se abrasion of the wire, or of the walls of the tapering hole in the dia or plate, and quickly put an end to the operation. In drawing coarse or large sizes of pire, say & inoh diameter, the pressure upon the sides of the tay~dng hole, where the wire comes i.u contact with the die, so great that an ordina,y labricaot is equeezed out when the nsoal rc~luctions iu size are matie, and abrasion takea place. In order to meet this diffic:ulty, and emure proper lubrication, it has been a ccmmon prtictice for yazrs to apply a paste made of rye or wheaten flour, or lime, to the surface of the wire to be drawn, and when the pnstc is dry, to smwr tl~e wire with tallow or grease; the wire is then ready to be draw, the dried pa serving fo prevent the lubricant from being presetf out in the prows. Some years since, when Bessemer metal came iargely into use material for wire, 'the writer fourid that its dmwing requid so much more power than iron wire, that he was led to institute a. series of trials to ascertain the difference in power required. It was fotind that Bessemer wire requircd from 100 to 200 per cent. more power to makc the same reduction in sizes than soft iron wire, the difference depending npou the amount of carbon and other chemical constitu-

Jan 1, 1881

By Henry Mulryan

The largest and purest known deposit of diatomite is being actively mined and processed 3 1/2 miles south of Lompoc, Santa Barbara County, Calif., by the Johns-Nlanville Products Corporation. The workings cover 4000 acres, the depth of economically recoverable diatomite being 1000 ft. (Fig. 1). Lompoe, a community of 2500 population, is situated in the Santa Ynez River Valley 10 miles inland from the Pacific Ocean. It is 44 miles

Jan 1, 1938

By Henry Mulryan

The largest and purest known deposit of diatomite is being actively mined and processed 3 1/2 miles south of Lompoc, Santa Barbara County, Calif., by the Johns-Nlanville Products Corporation. The workings cover 4000 acres, the depth of economically recoverable diatomite being 1000 ft. (Fig. 1). Lompoe, a community of 2500 population, is situated in the Santa Ynez River Valley 10 miles inland from the Pacific Ocean. It is 44 miles

Jan 1, 1938

By A. J. Weinig

The method described is a modification of Schutzenberger's whereby the solution in titrations and the standards are protected from the atmosphere by a layer of kerosene. Indigo-disulfonate is the indicator and sodium hydrosulfite the standard. The method is rapid and delicate. It has been tried on a variety of mill solutions and mill men have found the method of value. THE important part that dissolved oxygen plays in the cyanide treat-ment of gold and silver ores is commonly recognized by most metallurgists and mill men.. But heretofore there has been no simple method on which the mill man could rely for determining the amount of oxygen in the various mill solutions. A few methods are adaptable to the, laboratory, such as the gasometric1 determination by actually measuring the oxygen. Winkler's2 iodometric method, and Schutzenberger's3 method, which depends on the reducing action of sodium hyposulfite on a blue solution of indigo carmine; but these are not readily adaptable to the needs of the mill man and cannot be applied to cyanide solutions without modification. The gasometric method is the most accurate but it takes too long to complete a determination. White's' method (a colorimetric method that depends on the degree of coloration imparted to a solution of pyrogallic acid in the presence of caustic soda) although much more rapid than any of the methods named, often gives misleading results on account of grading of colors of different solutions, which nearly always contain various kinds of salts. The method herein described was devised for the use of the mill man, the aim being to develop a simple, practical, accurate method. It is a modification of the Schutzenberger method and depends on the reducing

Jan 8, 1924

By A. L. Jr. Pozzi, A. O. Garder, D. W. Peaceman

A new numerical method is proposed for the solution of multidimensional miscible displacement problems. Besides the usual stationary grid associated with numerical procedures, the method uses moving points for which positions and concentrations are computed each time step. Based on the method of characteristics for treating combined transport and dispersion, the method applies equally well to any number of dimensions and, in contrast with other numerical procedures, properly takes into account the physical dispersion, no matter how small. Extensive tests show that accurate solutions of one-dimensional problems can be obtained over a wide range of values of the dispersion coefficient, including zero. They also show that the moving points do not need to be uniformly spaced, and that increasing the number of moving points beyond 2/grid interval does not significantly improve the accuracy of the solution. Two-dimmsional calculations using the new method were carried out to simulate laboratory model displacements in which gravity caused overriding of solvent. Good agreement between observed and computed profiles and measured and computed concentrations of produced fluid was obtained for a viscosity ratio of 1.89; at higher viscosity ratios, fair agreement was obtained Computed results were found to be significantly affected by vertical dispersion, and negligibly affected by dispersion in the direction of flow, in agreement with conclusions based on experimental observations. INTRODUCTION Although miscible displacement processes are potentially of great economic significance, limited progress has been made in developing mathematical methods for predicting the outcome of a solvent flood. Because of the complexity of the partial differential equations which describe multidimensional miscible displacement, numerical methods are a natural approach to their solution. The task of finding suitable numerical approximations to one of the partial differential equations, which involves both dispersion and convective transport, has been particularly difficult. Dispersion in the absence of transport is described by the heat flow equation, a second-order equation of parabolic type. This equation has been very successfully treated by numerical methods. Transport in the absence of dispersion is described by a first-order equation of hyperbolic type. This equation has been treated numerically with some success in one dimension, both by Lagrangian and Eulerian techniques, 1.2 but extension to two or more dimensions has not been satisfactorily accomplished. Usually one of two things happens: either the numerical solution develops oscillations or it becomes smeared by artificial dispersion resulting from the numerical process. When transport and dispersion are considered simultaneously, this numerical dispersion may dominate the low physical dispersivicy that generally characterizes miscible displacement. Stone and Brian2 have developed a new difference equation for treating combined transport and dispersion in one dimension. By suitable choice of certain parameters, they succeeded in markedly reducing both oscillation and numerical dispersion. However, a satisfactory extension to higher dimensions has not yet been found. Peaceman and Rachford3 presented a centered-in-time and centered-in-distance difference equation combined with a 1,transfer of overshoot" procedure which was demonstrated to work well in one dimension. The technique was applied to the two-dimensional miscible displacement problem, but subsequent calculations with zero dispersivity showed little change in results compared with the calculations they presented. This indicates that their method involved a numerical dispersion of the same order as the physical dispersion. The present paper describes an alternate method for solving the combined transport-dispersion

Jan 1, 1965

By Franklin R. Carpenter

In area, the Black Hills are about equal to the State of Connecticut. As the accompanying geological map indicates, they exhibit in the main a simple structure, presenting a central mass of granite and Archæan rocks, on all sides of which the later sedimentary rocks dip

Jan 1, 1889

By Arthur F. Colombo, Donald W. Frommer

With the opening of the Tilden mine near Ishpeming, MI, a new era in iron ore beneficiation was begun. A description of a U. S. Bureau of Mines investigation is summarized to illustrate the selective flocculation-deslime-flotation process developed by the Bureau and used at the Tilden concentrator, which is also briefly described. The operating parameters for the selective flocculation-cationic flotation of an oxidized taconite from the Mesabi range are discussed. A water reclamation system using lime and a cationic flocculant was applied to reclaim the effluents from a 900-pound-per-hour flotation pilot plant. About 80 percent of water requirements were recovered, and the calcium content of the reclaimed water was found to be more important than clarity in influencing the selective flocculation and flotation processes. Although reclaimed waters with about 10 ppm calcium registered turbidities of approximately 5,000 ppm SiO2 equivalents, the concentrates produced using these waters contained 64 percent Fe and 55.0 percent SiO2 and had accompanying iron recoveries of 75 percent. Lower grade concentrates resulted from using reclaimed water with higher calcium contents and lower turbidities.

Jan 1, 1976

By S. C. Jones, J. A. Davis

This paper describes displacement mechanisms of micel-lur solution slugs, displuced by a thickened water "mobility buffer", in a glass micromodel and in consolidated Berea sandstone cores. Colored motion pictures, taken through a microscope, recorded interactions on a pore-to-pore bash in the micromodel. Production and differential pressure data from consolidated cores previously waterflooded to residua1 oil saturation revealed displacement mechani.sm.s macroscopically. Oil is displaced miscibly, while interstitia1 water is displaced immiscibly by the injected micellar. solution slug. Part of this water is dispersed and carried near the lead ing edge of the .slug, and some may remain as a residual saturation. Thickened water displaces any residual water. It also emulsifies with the. slug material, thereby displacing it. The displacement sequence forms banks of oil and water with relatively constant fractional flows, saturations, and mobilities. The mobility of oil and water flowing ahead of the .slug defines .slug viscosity required for stable displacement. Equations are presented that describe. several aspecis of the displacement flow behavior: oil breakthrough, oil cut during production of the stabilized bank, breakthrough of banked water and the resulting decreased fractional flow of oil, fluid mobilities, etc. Breakthroughs, calculated from the equations, are compared with experimental data. Slugs of micellar sollution, ranging from 1 to 5 percent PV, produced unusually high oil recoveries (up to 100 percent) in previously waterflooded consolidated cores. Investigation of the effect of mobility buffer size on oil recovery indicated that recovery is reduced in 3-in. X 4-ft cores for mobility buffer sizes .smaller than 50 percent of the pore volume. Introduction A new oil recovery process,* conceived in 1962, utilizes a slug of micellar solution' that has sufficient viscosity to avoid an unfavorable mobility ratio with respect to the oil and water it displaces. These micellar solutions are composed of hydrocarbons, water, and surfactants, and may contain electrolytes and co-surfactants. The micellar solution is displaced by a "mobility buffer". The mobility buffer is a bank of reduced-mobility fluid, preferably an aqueous polymer solution. The entire system is displaced by unthickened water. This paper describes some of the microscopic and macroscopic displacement mechanisms observed during laboratory development of the fluids for a potential field test. Microscopic phenomena were observed photographically in a specially constructed glass flow model and macroscopic data were taken from constant rate, tertiary displacements conducted in Berea sandstone cores. Qualitative Description of Micellar Solution Flooding This section qualitatively describes displacement mechanisms that occur when a slug of micellar solution is injected into a previously waterflooded core. The slug completely removes oil from the portion of core it contacts, and banks oil in the process. The oil saturation in this bank and the flowing WOR reach definite, fixed values that are determined by water and oil mobilities and slug characteristics. This zone of constant WOR and oil saturation will be called "stabilized oil bank" in the following discussion. When this stabilized bank reaches the outlet end of the core, the oil cut jumps from zero to a constant value equal to the fractional flow of oil. Saline water has little or no solubility in the slug. Because of this. the slug displaces in-place brine immiscibly. During slug injection, most of the brine is displaced ahead of the slug, some is carried along in the leading portion of the slug, and part of the brine may become immobile. The immobile, residual brine is later miscibly displaced by thickened water. Displacement of all the oil and only part of the water during slug injection results in a higher fractional flow of oil ahead of the slug than occurs when all the water is displaced after injection of thickened water is begun. The slug spontaneously emulsifies fresh (low-salt content) water. By emulsification, the slug can become infinitely diluted, and hence totally displaced, by thickened water. Fluid saturations in the core are shown schematically in Fig. 1. Parts A and B show conditions before and after the start of the thickened-water injection, respectively. Since thickened water displaces any residual brine by-

Jan 1, 1969

By P. R. Gage, R. W. Bartlett

At high temperatues and reduced oxygen pressuves, molybdenum silicicles oxidize to form SiO(g) vathev than a passivating SiO2 film. This is a sevious problem for low-pressure applications of sili-cide-coated rejvactory tnetals. As oxiclalion pvoceeds, the higher oxidntion potential of silicon initially suppresses oxidation of molybdenum and silicon is depleted near the surface. Eventually, silicon depletion causes secondary passivation (SiO2) mid an active to passiue transition in oxidntion behavior at moderately low pressures. At very low pressures, silicon depletion continues until steady-state oxidation of both silicon and rnolyhdenum can proceed at rates propovtional to their initial stoicliiorrzetvies. Ohsel-vations of 'oxidatiou-rate belzcriliov at temperatures from 1101° to 1700°C and oxygen pressures from 10-7 to 1 at in were made using thermogravimetn'c, X-ray diffraction, and elect?*on-rtric?ro/,vobe techniqrres. The experimental results are in good agreement with calculated lirnits for the various types of behavior that were based on tlievtnochernicnl atzd dffusion rate data for the Mo-Si system. A protective oxide film normally forms during the oxidation of elemental silicon. However, at elevated temperatures and reduced pressures this film is not present and oxidation is rapid. wagnerl has shown that this behavior occurs because SiO(g) is more stable than SiO2. The behavior of the silicides at high temperatures is similar but more complicated. Molybdenum and several silicide compounds are involved and the chemical activity of silicon, or the equivalent silicon vapor pressure, can vary considerably in these phases. Also, diffusion in the silicides resulting from reactions in which a higher silicide is reduced to a lower silicide, or molybdenum containing dissolved silicon, must be considered. EXPERIMENTAL AND ANALYTICAL METHODS Isothermal oxidation experiments were conducted using hot-pressed MoSi2 and Mo5Si3 wafers. Each experiment was conducted at a fixed oxygen pressure by controlling the flow of oxygen in and out of the furnace chamber. Most of the experiments were conducted in a molybdenum-wound tube furnace. Special construction features, including use of a high-purity dense A12O3 refractory tube, permitted operation in high vacuum to 1500°C. Higher temperatures could be obtained at higher working pressures and with a sacrifice of tube lifetime. Temperature was measured with three Pt 6 pct Rh/Pt 30 pct Rh thermocouples and controlled with a proportional controller. Weight changes were monitored with a quartz spring balance. The few experiments, at higher temperatures and low pressures, were conducted in a cold wall vacuum chamber using induction heating with direct susceptance of the sample. Because of the variable levitation effect of the induction coil on the sample, weight changes could not be monitored continuously in these experiments. All samples representing both experimental methods were weighed before and after oxidiation and examined with a microscope and analyzed by X-ray diffraction. The analytical treatment assumes equilibrium at interfaces and uses existing thermodynamic data. For convenience, equilibria are expressed as chemical potentials or as vapor pressures of the gases involved. The resulting differences in equilibrium vapor pressure between adjacent interfaces and between the surface and external atmosphere drive diffusion processes in the solid and gas boundary film, respectively. These diffusion processes govern the rate of oxidation. A bibliography of the sources of thermochemical data for the reactions pertinent to the Mo-Si-O system is given in Table I. Reactions are listed with the sources of free-energy data referenced. Since all of these reactions involve one or more gas species, usually oxygen, a plot of the product-gas chemical potential, -RT In Pg, vs absolute temperature for each reaction is given in Fig. 1. These curves can be used to determine equilibrium vapor pressures or to compare the stability of different compounds in the various gases: O2, Si, SiO, and Moo3,. The data of Table I and Fig. 1 were used to determine the analytical results presented in this paper. EXPERIMENTAL RESULTS The weight changes for three MoSi, samples oxidized at 1500°C are plotted against time in Fig. 2. The treatments were identical except for the indicated variance of oxygen pressure and each curve represents one of three characteristic types of behavior that were observed. The upper curve is an example of passive oxidation, which is defined as

Jan 1, 1965

By Larry Dale

An approach for predicting the development of mineral resources on public lands has been developed as an aid to resource agencies. It consists of new techniques for evaluating the economic potential of the resource, the uncertainty about mine cost estimates, and the uncertainty about the occurrance of mineral deposits. New mineral sup- plies from inferred and hypothetical resources can be predicted by using these techniques. A case study illustrates their application in predicting development of copper resources in western Montana.

Jan 1, 1982