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By Jacques B. Wertz

Even with the best geological maps, there is a constant need for further information and a constant demand for new clues, particularly in exploration work. New ideas and new thoughts are a necessity for progress. In the structural study of an area, be it in Arizona, Africa, or British Columbia, the basic fracture pattern has to be determined first. There is, however, no assurance that the trends shown on the map are really meaningful because they often are secondary in nature, having occurred as a consequence of an intrusion, of doming, or of gravity faulting. Thus, such trends often are a weak basis for assuming the presence of ancient and important zones of fractures that could constitute useful guides to mineral exploration.

Jan 6, 1969

By Charles Barrett

RECRYSTALLIZATION textures-the orientations of grains after recrys-tallization-have been studied extensively not only because of their metallurgical importance but also because of the information they yield regarding the atomic movements during recrystallization. Recrystallized grains must possess the same orientations as the submicroscopic nuclei from which they have grown, and thus they offer a direct road by which experimenters can penetrate the submicroscopic realm. Many perplexing results have come of these studies, but one of the most striking has been the apparent difference in behavior between single crystals and polycrystalline grains. For example, Burgers and Louwerse have shown' that when single crystals of aluminum are deformed by compression and are recrystallized (at 600° C.) the new grains appear with orientations that are different from the orientations of the deformed crystal in which they grew; but polycrystalline specimens, on the other hand, appear to have a [110] fiber texture both before and after recrystal-lization and thus to retain their texture during recrystallization. This apparent difference between the habits of single crystals and small grains is the subject of the first part of the present research and has been explained by findings reported herein. A similar situation appears to exist for aluminum when elongated or drawn into wires, for single crystals alter their orientation2,3 and polycrystalline wires retain their texture 4,1 6 upon recrystallization after elongation (at least with high-purity alumi-num), and it is possible that the explanation found in this paper for compression can be extended to cover elongation and other types of deformation as well. The second part of this paper deals with the theory of recrystallization textures. In the most successful theory for aluminum recrystallized after compression,1 much weight is given to the orientation of highly stressed nuclei in the deformed material. Taylor's "local distortions" are assumed to exist along the slip planes where displacement has occurred, consisting of fragments rotated in a specific way with reference to the slip plane and slip direction; namely, about an axis lying in the slip plane perpendicular to the slip direction. 1,7,8,9

Jan 1, 1940

By Jerome Alexander

THE object of this paper is to show that many of the important phenomena of metals and alloys are due to the facts that, at some stage, metals and alloys, or some of their constituents, are in a colloidal state and that a portion of the metal or alloy tends to remain in this state. The so-called amorphous phase in pure metals is an isocolloid, consisting of colloidal groups of metal molecules that may be dispersed in still more finely subdivided metal; these colloidal particles are not truly amorphous, but may consist, in part, if not entirely, of ultramicroscopic crystals; as a result the expressions amorphous phase and amorphous theory might be replaced by the expressions colloidal phase and colloidal theory. Any substance is in the colloidal state when the constituent particles consist of molecular or atomic groups, whose size varies approximately from about 100µµ down to about 5µµ, that is from just below the limit of microscopic resolvability to the dimensions commonly ascribed to the larger molecules. Colloidality involves no assumption as to the shape, internal structure, or orientation of the colloidal particles; size alone is the critical factor. A colloidal system may therefore contain crystalline groups, or amorphous groups (non-crystalline, random or haphazard clusters), or a mixture of the two. All colloids consist of at least two phases, the subdivided substance, or dispersed phase, and the substance into which this is subdivided, the dispersion medium. It is not necessary that there be any chemical difference between the dispersed phase and the dispersion medium. As molecular forces are extremely powerful, their application may produce marked changes in the physical properties of metals. It is doubtful whether metal in the interior, especially of large masses, possesses the same properties as that on or near the surface, which alone is open to, inspection.

Jan 10, 1920

By H. Rush Spedden, A. M. Gaudin

Although the number of minerals that are ferromagnetic‡ or highly paramagnetic is strictly limited, it has been known for some time that many minerals have slight but supposedly characteristic magnetic susceptibilities. With the exception of pyrrhotite, however, sulphides have been thought nonmagnetic. A new magnetic separator has been made available recently in limited quantity to research laboratories. This device, the Frantz Isodynamic Separator, has been used for the separation of various non-sulphides from each other. Its application to the separation of sulphides, however, does not seem to have been reported. In the Richards Mineral Dressing Laboratories, the success achieved through the use of this device in separating associated sulphides has been so startling as to lead us to believe that it constitutes a magnificent adjunct to heavy-liquid separation and to quantitative mineragraphy as a tool for the mineral investigator. The separator (Fig. I) consists of: 1. A powerful magnet, the strength of which can be adjusted by, means of a rheostat; 2. A vibrating chute of nonmagnetic metal on which the mineral to be separated is made to flow (Fig. 2); 3. A feed bin and adjustable feeder; 4. Receptacles for the collection of products; 5. Means for changing, setting, and accurately reading the two slopes of the chute; viz., the cross slope and longitudinal slope. The separator is made operative by the special shape of its pole pieces, which ensures a strongly converging field. It is said by the makers of the machine that the pole pieces apply a constant mechanical force to a particle of given susceptibility, regardless of its position in the operating space of the separators." Susceptible particles, therefore, behave as though of lower specific gravity than under ordinary circumstances. This effect, combined with the slopes of the chute and the action of the vibrator, causes a stratification not unlike thai obtainable on a shaking table. The chute is of rectangular cross section, and shallow; it is broadened toward the discharge end and divided longitudinally by a partition into two compartments that lead to the collecting receptacles. Although the separator probably can be used to make separations at fairly coarse

Jan 1, 1943

By H. Rush Spedden, A. M. Gaudin

Although the number of minerals that are ferromagnetic‡ or highly paramagnetic is strictly limited, it has been known for some time that many minerals have slight but supposedly characteristic magnetic susceptibilities. With the exception of pyrrhotite, however, sulphides have been thought nonmagnetic. A new magnetic separator has been made available recently in limited quantity to research laboratories. This device, the Frantz Isodynamic Separator, has been used for the separation of various non-sulphides from each other. Its application to the separation of sulphides, however, does not seem to have been reported. In the Richards Mineral Dressing Laboratories, the success achieved through the use of this device in separating associated sulphides has been so startling as to lead us to believe that it constitutes a magnificent adjunct to heavy-liquid separation and to quantitative mineragraphy as a tool for the mineral investigator. The separator (Fig. I) consists of: 1. A powerful magnet, the strength of which can be adjusted by, means of a rheostat; 2. A vibrating chute of nonmagnetic metal on which the mineral to be separated is made to flow (Fig. 2); 3. A feed bin and adjustable feeder; 4. Receptacles for the collection of products; 5. Means for changing, setting, and accurately reading the two slopes of the chute; viz., the cross slope and longitudinal slope. The separator is made operative by the special shape of its pole pieces, which ensures a strongly converging field. It is said by the makers of the machine that the pole pieces apply a constant mechanical force to a particle of given susceptibility, regardless of its position in the operating space of the separators." Susceptible particles, therefore, behave as though of lower specific gravity than under ordinary circumstances. This effect, combined with the slopes of the chute and the action of the vibrator, causes a stratification not unlike thai obtainable on a shaking table. The chute is of rectangular cross section, and shallow; it is broadened toward the discharge end and divided longitudinally by a partition into two compartments that lead to the collecting receptacles. Although the separator probably can be used to make separations at fairly coarse

Jan 1, 1943

By Emil Gathmann

INTRODUCTION. IN presenting this paper I will attempt to answer certain questions proposed at this meeting and describe and illustrate methods of producing sound steel in an economical and hence commercial manner, which are adaptable to the production of practically all steel manufacturers, by readily effected rational changes in the methods of casting, cooling, and subsequent handling of the ingots. In some of the high-grade mills of America, where it is essential to obtain perfectly sound billets or blooms, it is the practice to discard from 35 to 40 per cent. of the crop- or pipe-end, and even with this excessive discard, secondary pipe or shrinkage-cavities are frequently discovered during subsequent working of the blooms and billets into their various manufactured products. The usual discard of from 10 to 20 per cent. from the crop-end of the ingot, which is made by the present generally employed methods of form and solidifying of the castings, certainly does not give the slightest assurance of the saleable product being physically sound or chemically homogeneous. I am aware that in the past there has been and at the present time there still is a decided difference of expert opinion as to what constitutes physically sound steel.

Jan 4, 1913

By H. Rush Spedden, A. M. Gaudin

ALTHOUGH the number of minerals that are ferromagnetic) or highly paramagnetic is strictly limited, it has been known for some time that many minerals have slight but supposedly characteristic magnetic susceptibilities. With the exception of pyrrhotite, however, sulphides have been thought nonmagnetic. A new magnetic separator has been made available recently in limited quantity to research laboratories. This device, the Frantz Isodynamic Separator, has been used for the separation of various nonsulphides from each other. Its application to the separation of sulphides, however, does not seem to have been reported. In the Richards Mineral Dressing laboratories, the success achieved through the use of this device in separating associated sulphides has been so startling as to lead us to believe that it constitutes a magnificent adjunct to heavy-liquid separation and to quantitative mineragraphy as a tool for the mineral investigator. THE SEPARATOR The separator (Fig. I) consists of: I. A powerful magnet, the strength of which can be adjusted by means of a rheostat; 2. A vibrating chute of nonmagnetic metal on which the mineral to be separated is made to flow (Fig. 2); 3. A feed bin and adjustable feeder; 4. Receptacles for the collection of products; 5. Means for changing, setting, and accurately reading the two slopes of the chute; viz., the cross slope and longitudinal slope. The separator is made operative by the special shape of its pole pieces, which ensures a strongly converging field. It is said by the makers of the machine that the pole pieces apply a constant mechanical force to a particle of given susceptibility, regardless of its position in the operating space of the separators.* Susceptible particles, therefore, behave as though of lower specific gravity than under ordinary circumstances. This effect, combined with the slopes of the chute and the action of the vibrator, causes a stratification not unlike that obtainable on a shaking table. The chute is of rectangular cross section, and shallow; it is broadened toward the discharge end and divided longitudinally by a partition into two compartments that lead to the collecting receptacles. Although the separator probably can be used to make separations at fairly coarse

Jan 1, 1943

By W. Rutledge

As is well known, the Sydney coal-field comprises an area of about 200 square miles, being about 32 miles from the month of Big Bras d' Or, on the northwest, to Mira Bay on the southeast, by about 6 miles in width. The whole of this area is underlain by

Jan 1, 1886

By J. R. Lewis, J. H. Hamilton, V. D. Hanson, K. W. Heinlein, J. M.194-000-000-006 Vonfeld, J. P. Denny

TWO overfeed drum-type separators using a suspension of magnetite in water as the separating medium have been installed in the Champion NO. 1 preparation plant of the Pittsburgh Coal Co., Division of the Pittsburgh Consolidation Coal Company. A simplified flow diagram of the Champion No. 1 coarse coal circuit is shown in Fig. 1. A railroad car rotary dump, capable of handling 20 cars per hr, discharges the coal into a hopper. Coal is fed from the hopper of the rotary dump to a 60-in. belt conveyor by two reciprocating pan-type feeders. The belt conveyor feeds the run of mine coal onto the main raw coal screen. The first deck is fitted with 3 in. round hole perforated plate which removes the 3x0-in. coal. The second deck of the screen is equipped with 6-in. lip screens which separate the remaining coal into +6 in. and 6x3 in. The +6 in. coal is transferred to a shaking picking table and then discharged onto the loading boom. The 6x3-in. coal is fed to the No. 2 dense medium vessel for cleaning. The clean coal from this unit flows to a vibrating screen where the medium is removed and the coal sized into 6x4 in. and 4x3 in. The 6x4-in. coal is transferred to the loading booms and the 4x3-in. is conveyed to the clean coal classifying screens to remove degradation. The 3x0-in. raw coal is blended in a system composed of three storage bins having a total capacity of 400 tons. From these bins the coal is fed onto a 48-in. flight conveyor by three reciprocating feeders. This flight conveyor delivers the coal to the Rheo plant. The 3x0-in. coal is then cleaned in two 48-in. Rheolaveur launders each equipped with two Rheo boxes. The first set of boxes removes a primary refuse and the second set produces a middling product which is recirculated in the launders. The cleaned coal and water overflows from the primary launders to two sizing and dewatering shaker screens where the water and — -in. coal are removed for further cleaning in the Rheo fine coal plant. The 3x3h-in. clean coal is combined with the 4x3-in. coal from the No. 2 vessel, sized into 4x2 in., 2x1 34 in., and 1'/4x in., then sent to the loading booms. The 3x0-in. refuse from the primary launders is normally fed to the No. 1 dense medium circuit, but any portion or all of this material can, as an alternate, be processed in the Rheo rewash launder. The primary refuse when fed to the dense medium circuit is screened into YSXO which is cleaned in the fine coal plant and 3x for cleaning in the No. 1 vessel. The clean coal from this vessel is passed over a vibrating drainage and rinse screen, then sluiced to the rewash sizing shaker where it is dewatered and sized for loading. The installation of a pilot plant separating vessel using a suspension of magnetite in water was pro-

Jan 1, 1953

By J. H. Hamilton, J. R. Lewis, K. W. Heinlein, V. D. Hanson, J. M. 194-000-000-006 Vonfeld, J. P. Denny

TWO overfeed drum-type separators using a suspension of magnetite in water as the separating medium have been installed in the Champion NO. 1 preparation plant of the Pittsburgh Coal Co., Division of the Pittsburgh Consolidation Coal Company. A simplified flow diagram of the Champion No. 1 coarse coal circuit is shown in Fig. 1. A railroad car rotary dump, capable of handling 20 cars per hr, discharges the coal into a hopper. Coal is fed from the hopper of the rotary dump to a 60-in. belt conveyor by two reciprocating pan-type feeders. The belt conveyor feeds the run of mine coal onto the main raw coal screen. The first deck is fitted with 3 in. round hole perforated plate which removes the 3x0-in. coal. The second deck of the screen is equipped with 6-in. lip screens which separate the remaining coal into +6 in. and 6x3 in. The +6 in. coal is transferred to a shaking picking table and then discharged onto the loading boom. The 6x3-in. coal is fed to the No. 2 dense medium vessel for cleaning. The clean coal from this unit flows to a vibrating screen where the medium is removed and the coal sized into 6x4 in. and 4x3 in. The 6x4-in. coal is transferred to the loading booms and the 4x3-in. is conveyed to the clean coal classifying screens to remove degradation. The 3x0-in. raw coal is blended in a system composed of three storage bins having a total capacity of 400 tons. From these bins the coal is fed onto a 48-in. flight conveyor by three reciprocating feeders. This flight conveyor delivers the coal to the Rheo plant. The 3x0-in. coal is then cleaned in two 48-in. Rheolaveur launders each equipped with two Rheo boxes. The first set of boxes removes a primary refuse and the second set produces a middling product which is recirculated in the launders. The cleaned coal and water overflows from the primary launders to two sizing and dewatering shaker screens where the water and — -in. coal are removed for further cleaning in the Rheo fine coal plant. The 3x3h-in. clean coal is combined with the 4x3-in. coal from the No. 2 vessel, sized into 4x2 in., 2x1 34 in., and 1'/4x in., then sent to the loading booms. The 3x0-in. refuse from the primary launders is normally fed to the No. 1 dense medium circuit, but any portion or all of this material can, as an alternate, be processed in the Rheo rewash launder. The primary refuse when fed to the dense medium circuit is screened into YSXO which is cleaned in the fine coal plant and 3x for cleaning in the No. 1 vessel. The clean coal from this vessel is passed over a vibrating drainage and rinse screen, then sluiced to the rewash sizing shaker where it is dewatered and sized for loading. The installation of a pilot plant separating vessel using a suspension of magnetite in water was pro-

Jan 1, 1953

By Pol Duwez, Ellis P. Frink, Paul Pietrokowsky

Ti-Au alloys in the composition interval 0 to 66 213 atomic pct Au have been studied over a temperature range from 400° to 1500°C. A partial phase diagram has been established from micrographic and macroscopic observations. All intermediate phases, Ti3Au, TiAu, and TiAu., exhibit open melting maxima. It has been observed that small additions of gold lower the allotropic transformation temperature of titanium. The P solid solution decomposes eutectoidally to a solid solution plus Ti3Au. The solubility of gold in a solid solution decreases with temperature. THERE have been several papers in the literature pertaining to the alloy system Ti-Au. However, a comprehensive study of this interesting constitu- tion diagram has not been conducted. Previous investigations have been concerned with the crystal structure of intermediate phases or partial phase diagrams. This paper represents a partial constitution diagram, Ti-TiAu,, the first portion of an investigation of the entire binary system. Laves and Wallbaum' reported the intermediate phase Ti,Au to be isomorphous with CuAu, L12 type. In a more recent paper, Duwez and Jordan' have concluded that TiAu has an atomic arrangement which is related to Cr,Si. The intermediate phase

Jan 1, 1957

By Sir John Cadman

Since my previous review of the Persian fields, presented in 1929,' considerable progress has been made. The main feature of drilling development has been the delimitation of the Haft Kel field and its extensions. Although the limits have not yet been reached, a productive area of about 40 square miles has already been proved and it is now certain that the field will be of the same order of importance as the Masjid-i-Sulaiman field. Production to main pipe line from Haft Kel was begun in November, 1929, and to date about 4,500,000 tons have been produced. Normal production has continued from the Masjid-i-Sulaiman and Naft Khaneh fields. The search for oil in horizons below the main producing limestone is perhaps the most interesting and important exploratory drilling work in progress. Promising results have been obtained in the first well deepened in the Masjid-i-Sulaiman field with this objective, and the exploration of these lower formations is being continued. In this connection an allied program of geochemical research work on the nature of the oils and oil-bearing rocks of different horizons is at, present being undertaken. Masjid-i-Sulaiman Field Since the Haft Kel field was brought into production in 1929, production from Masjid-i-Sulaiman has been reduced in order to equalize to some extent the producing lives of the two fields. The production for the last four years has been as follows: m Approximate Equivalent in TonB Barrels 1929 5,434,071 38,038,497 1930 4,925,869 34,481,083 1931 4,248,086 29,736,602 1932 Approximately 4,500,000 31,500,000

Jan 1, 1933

By E. Hornbogen, R. C. Glenn

Copper precipitates from a iron as fcc E phase without formation of intermediate compounds. In the first stage of the precipitation, spherical particles with diameters < 100A are formed at a high rate. During the second stage, the particles grow at a rate given by Zener&apos;s equation for growth of a spherical precipitate. In the third stage, growth is slower. Rod-shaped particles form after long aging times at 700°C. Maximum strengthenzng was observed at the beginning of the second step of precipitation. During plastic deformation of the aggregate, particles appear to deform initially by twinning. THE work discussed herein was part of a study of precipitation of substitutional elements from a iron. Copper was chosen as one of these substitutional elements because it has about the same atomic size as a iron, and does not form an intermetallic compound with iron. The data on the iron-copper system then available were summarized by Daniloff1 several years ago. The solubility of copper in a iron has been determined by electrical conductivity measurements,2 lattice parameter measurements,3 and by saturating thin iron foils with copper and determining the copper content.4 The results of the three investigations do not agree very well, but the value of 2.4 wt pct for the maximum solubility at 840°C seems to be the most reliable,4 Fig. 1. An alloy containing 1.23 wt pct Cu was used in our work to assure starting with a completely homogeneous material. On the copper-rich side of the diagram, there is a maximum solubility of about 4 wt pct Fe in copper at 1094°C ( phase). The precipitation of

Jan 1, 1961

By Robert L. Clayton, Arthur Baker

Two massive sulfide zinc-copper ore bodies are in quartz-sericite schist (probably formed by regional metamorphism of sediments) and andesite of the Precambrian Yavapai Series, on opposite sides of a large rhyolite mass. The Copper Queen ore body is conformable with bedding of its schist host rock, but the Old Dick ore body probably crosscuts the strata. A lens of low-grade mineralization in chlorite schist, associated with the Old Dick ore body, crosscuts through 150 feet of strata. The ore bodies are almost entirely enclosed by premineral faults with less than 150 feet of displacement. The minerals of the ores are pyrite, sphalerite, and chalcopyrite, with minor arsenopyrite and galena and small amounts of intimately associated chlorite, sericite, and calcite. Old Dick sphalerite-chalcopyrite intergrowths have mutual boundaries, and sphalerite grains contain abundant exsolved chalcopyrite. Copper Queen sphalerite-chalcopyrite intergrowths have extremely ragged boundaries, the sphalerite contains no exsolved chalcopyrite, and the ore overall has a schistose texture. The pre-mineral fault on the hanging wall of the Copper Queen ore body has had 100 feet of post-mineral displacement. Wall rocks of the Old Dick ore body locally have been sericitized. Andesite and quartz-sericite schists for at least several hundred feet around both ore bodies have been chloritized erratically and contain traces of copper.

Jan 1, 1968

By A. G. McGregor

In the Southwest a number of large steel chimneys discharge the gases from the copper smelting furnaces. Some of these chimneys show no deterioration after twenty years, others show serious deterioration after tour years service. A steel stack 20 ft. 7 1/2 in. (6.3 m.) in diameter by 279 ft. (85 m.) high, Fig. 1, used for roaster gases only at the Calumet & Arizona Mining CO.&apos;s plant at Douglas, Ariz., was lined to the top of the bell, 40 ft. (12 m.) from the base, with common brick placed on end, lime and cement mortar being used. Above the bell, the stack was lined with 4 by 4 by 8 in. (10 by 10 by 20 cm.) building tile, placed on end, making a lining 4 in. thick. The tiles were supported on angle-iron rings, riveted to the inside of the chimney shell about 15 ft. apart. The chimney was put into use in the latter part of 1913. Four years later, considerable of the tile lining had fallen out of place and mixed with the flue dust at the bottom of the chimney. About a year later, several flattened and distorted sheets were noticed about 70 ft. below the top. An investigation showed that the thickness of these distorted sheets, which was originally 1/4in., had been reduced one half. One year later, or six years after the chimney went into use, several holes, a square foot and smaller in area, appeared near the flat spots mentioned. Soon afterwards, when the chimney was shut down for repairs, it was found that most of the tile lining for 125 ft, from the top had fallen out and that the steel shell was badly corroded; but where the lining remained in place the shell was undamaged. Many of the tile which had fallen out of place had become soft or flaky and crumbling, others were as hard as when placed. An analysis of the hard and soft tile is shown on p. 2. These tile were of a fireclay mixture, and were used instead of common brick on account of lower cost. The steel forming the upper 125 ft. (38 m.) was replaced, and a 4 1/4-in. (11-cm.) lining of firebrick was laid from the bell to the top of the chimney. The brick were placed on end, wedges and keys being used. After each 8-in. course was set, keyed, and wedged tight, thin mortar —water, sodium silicate, and finely ground silica—was worked into the joints. The brick are supported on angle-iron rings, every 15 ft., in the same way as the tile.

Jan 1, 1921

By Archibald Blue

JUST one hundred years ago, in a paper read before the Royal Society of London and published in its Transactions, Rt. Hon. Charles Greville established and named the mineral species, corundum, the crystalline oxide of aluminum; and we have it on the authority of Professor Judd that in an appendix to Greville&apos;s paper the Count de Bournon correctly defined the crystallographic characters of the species. The names of its

Jan 1, 1899

By GEO H. DEIKE

NOT much activity has been evident during the past year in the establishment of co-operative scholarships but the interest among the coal-mining companies is more pronounced than ever. This is apparent from the replies received to a letter sent out by the Committee on the Promotion of Student Interest in Coal Mining to over 120 coalmine operating officials. With that letter was forwarded a bulletin issued by the school of mineral industries of The Pennsylvania State College entitled ?Industrial Scholarships ? a Partnership of Industry and Education.? In that circular was outlined the need for trained men in the war and postwar world, and particularly as such demands pertain to the growth of the mineral industries.

Jan 1, 1943

By Everett Carpenter

THE average daily production of crude oil-in Kansas a1 the beginning of the year was about 71,000 1 bbl. and, at its close, 82,000 bbl.-an increase of 11,000 bbl. per day. The total production for the state during the year was about 28,250,000 bbl., or an average of practically 77,500 bbl. per day for the year. This increase in the production was the result of the discovery of several new pools of high-grade oil. COWLEY AND SUMNER COUNTIES One of the principal factors in bringing the production of the. state back to its former level was the newly discovered pools in western Cowley County. During December, 1923, the Waite Phillips Co. completed its Johnson No. 1 in Sec. 20, T. 33 S., R. 3 E., which opened up the Rainbow pool about 12 miles southwest of Winfield. In this pool, the production comes from the Burbank sand, locally called the "Rainbow," found at a depth of 3200 ft. The sand varies in thickness from 25 to 40 ft. in the seventeen wells completed during the year, and the initial productions ranged from 300 to 3000 bbl. per day of 40° Be. oil. The Rainbow pool is purely a wildcat discovery, for no. rocks suitable for the use of the geologist are present. To determine the geologic conditions, the larger companies core-drilled the Rainbow area immediately after the discovery. The Marland Refining, Co., drilling on the Graham farm in Sec. 9, T. 33, R. 3, failed to find the Burbank sand and continued to the Siliceous lime, often erroneously called the Wilcox, at 3505 ft., where a well with an initial production of 900 bbl. of 40 Be. oil was obtained. In the development following this discovery, 4 additional wells were completed, 3 of which encountered pay sand at 2500 ft., the initial productions each being about 200 barrels. Judging by the sands already proved and the area indicated as probably oil bearing by the development to date, these pools have a very promising outlook for the future. It is not unlikely that a field second only to El Dorado may have been opened.

Jan 3, 1925

By Douglas R. Cook

The discovery of the gold deposits of the Jerritt Canyon district, with proven recoverable reserves in excess of 67.6 Mg (2.4 million oz) of gold, has contributed greatly to the tremendous resurgence in exploration for disseminated gold deposits in Nevada and throughout the west. The Jerritt Canyon project, including the Bell mine, is a 70130 joint venture between Freeport Gold Co. and FMC Gold Corp., both of which are wholly owned affiliates of the respective parent companies, Freeport-McMoRan Inc. and FMC Corp. The Jerritt Canyon district is located in the center of the Independence Mountains in north-central Elko County, Nevada, approximately 48 km (30 miles) northeast of the Carlin gold mine and 68 km (42 miles) north of Elko. Although the discovery of a commercial gold mine at Jerritt resulted from Freeport&apos;s exploration activities, the initial identification of a gold prospect in this area was a consequence of a program by FMC in the search for antimony. Their program was, in part, based on data in the Nevada Bureau of Mines Bulletin 61, "Antimony Deposits in Nevada." Work on the property began in 197 1 with geologic mapping followed by sampling and geochemical analyses. FMC geologists, including Robert Hawkins, Russell Hayden, and Hal Hurst recognized the striking similarity of the area to the geologic environment of Newmont&apos;s nearby Carlin gold deposit and soon focused on the gold potential. Increases in the price of gold served to stimulate interest and support for the exploration program. Geochemical samples were collected and analyzed for gold and trace elements usually associated with gold. A strong gold anomaly was found on the North Fork of Jerritt Canyon, which was called the Alchem anomaly. Drill-testing of this anomaly in 1973 revealed significant grades and thicknesses of gold mineralization in the lower portion of the Roberts Mountain formation. This initial discovery and subsequent close-spaced drilling proved the existence of several small pods of low-grade, gold-bearing material which cropped out at their up-dip edges, causing the surface anomaly. The mineralization was very encouraging, but was not, by itself, of economic importance from the standpoint of either grade or tonnage. Freeport Exploration Co. established a district office in Reno in late 1974 with responsibilities for exploration of hard minerals in the Basin and Range Province. Emphasis of the program was directed to the discovery of precious metal deposits. Enfield Bell, as District Manager for this new office, was particularly interested in the Independence Mountains and when the opportunity for a joint venture with FMC became available in 1976, it was aggressively pursued. Enfield Bell and David Stevens evaluated the FMC data and with the support of management formulated a bid in competition with 23 other companies. Freeport was selected by FMC as partner and a joint venture agreement was successfully negotiated. In mid-summer of 1976, Freeport Exploration Co. began an expanded program of detailed mapping and geochemical sampling under the direction of Bell and Stevens that led to new interpretations of the structural and alteration patterns. Hawkins&apos; contribution during this period must be recognized since he not only was one of the original geologists assigned to the antimony and subsequently the gold investigations, but shortly after the start of the joint venture exploration, he was hired by Freeport Exploration Co. as the project geologist for the venture. Hawkins had studied the central Independence Mountains for his thesis and his understanding of the regional geology provided an excellent background for the continued exploration of the gold de- posits. His interpretation of the structure in the vicinity of the Alchem anomaly was of significant help in the Freeport exploration program. Drilling, based on this new under- standing of the geology, revealed the edge of the Marlboro Canyon ore body, which is now being exploited in the Bell mine. Although a classic bullseye geochemical target led to the discovery of the Alchem mineralization, the bulk of the reserves known today in the Marlboro Canyon area lay

Jan 1, 1985

By Robert F. Brindisi

There are approximately thirty to forty operating mills in the United States which are currently producing uranium yellow cake. This figure includes a significant number of in situ and by-product operations however the conventional acid leach flowsheet depicted in Figure 1 is the most common process used by domes- tic yellow cake producers. Ground ore is leached with sulphuric acid and the solids are separated from the pregnant liquor and washed in a series of counter- current decantation thickeners. After clarification of the pregnant liquor, uranium is recovered from the solvent extraction/stripping circuit by the addition of ammonia with precipitation of ammonium diuranate, or simply yellow cake. The yellow cake precipitate is then thickened in a conventional thickener before re- porting to the dewatering/washing unit operation. De- watered solids subsequently report to thermal drying, and clarified liquor from the dewatering/washing step is recycled to the yellow cake thickener. The yellow cake dewatering/washing unit operation is generally accomplished using either a solid bowl centrifuge or a rotary vacuum drum filter. In most cases the underflow from the yellow cake thickener is pumped to the dewatering/washing unit operation at approximately fifteen to twenty percent solids. For the purpose of this discussion ammonium diuranate, the product of ammonia precipitation from a conventional acid-leach uranium mill flow sheet, as discussed earlier, will be considered. With only slight adjustment this discussion will be equally applicable to sodium diuranate or uranium perioxide precipitates and to either in situ or by-product operations where such precipitates are generated. Some of the domestic uranium mills which have selected solid bowl centrifuges instead of vacuum drum filters for the dewatering/washing unit operations are listed in Figure 2. Why have these uranium mills, as well as others not listed, chosen to use the solid bowl centrifuge for this particular application? It is simply a matter of performance, reliability and economics. In the remainder of this paper the performance, initial cost, installation cost, maintenance and power consumption of both the solid bowl centrifuge and the rotary vacuum drum filter will be com- pared. In order to provide a consistent basis for comparison the appropriate sized (centrifuge or filter) unit for the dewatering/washing of 400 to 500 pounds per hour of yellow cake solids will be considered. Such a flow will usually be generated by a typical 3,000 ton per day (acid-leach) uranium mill.

Jan 1, 1980