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By J. A. Holmes

Venezuela has continued during 1929 to demonstrate that it is destined for many years to come to be one of our most important sources of crude petroleum. The producing fields of the Bolivar Coastal district along the east side of Lake Maracaibo have continued their phenomenal production, and two new fields have reached the near producing stage, while the results of deep test wells have strengthened the predictions and expectations that oil will be found and produced from many other pools and from several different geological formations. The finding of these new oil pools is not going to be easy, because the surface evidences of geological structure are scanty, and the subsurface problems are difficult, but intelligent effort backed by ample resources may be counted upon to overcome these obstacles and lead to a continued increase in the number of producing fields in Venezuela. During 1929 the total production of Venezuela was approximately 135,953,000 bbl., an increase of nearly 30,000,000 bbl., or 28 per cent., as compared with the preceding year. During 1929 oil in steel storage in Venezuela decreased from 13,000,000 to about 11,000,000 barrels. Tables 1, 2 and 3 briefly summarize Venezuelan production by fields and by years, and show the trend of production since its establishment on a commercial basis. Table 1.---Production of Crude Oil in Venezuela by Years, 1917 to 1929 All Figures in Barrels of 42 Gallons Total PRodUction Total PRoduction Year VeneZUela, Bbl. Year Venezuela, Bbl. 1917....................... 227,000 1927.................... 63,181,000 1918....................... 368,000 1928.................... 106,000,000 1919....................... 258,000 1929.................... 135,953,000* 1920..................... 548,000 Grand Total Since Ineep- 1921...................... 1,544,000 tion................... 380,791,000 1922....................... 2,448,000 Increase, 1929 over 1928.. . 29,953,000 1923..................... 4,170,000 Per cent. Increase......... 28.2 1924....................... 9,234,000 Per cent. 1929 Production 1925....................... 20,219,000 of Total............... 35.7 1926....................... 36,641,000 * Includes estimate for closing period of 1929.

Jan 1, 1930

By H. B. Pulsifer

The unprecedented high price of zinc ore prevailing through the early months of 1915 caused great activity in the Joplin district of Missouri. The Media mill is conspicuous as one of the first of the new "big mills" of the district. The mill was built over a mine previously worked but abandoned in 1912 because of the leanness of the ore and the large quantity of water encountered. The ore prices prevailing—$100 a ton in June, 1915, as against $50 in 1912-—favored the new undertaking. The mill was designed for good recovery so that it might operate in times of depression. In design and equipment, the mill is exclusively local in conception and construction. Former Exploitation The tract of land is a part of the large Guinn holdings; 70 acres are comprised in this particular lot, which is situated just a mile north of the center of Webb City on the Alba line of the Southwest Missouri Electric Railway. The ore lies 242 ft. below the surface at the top of the knoll which is surrounded by the well known properties: Black Cat, Ground Floor, Florence, Hurry-Up, Electrical, and Mercantile. Since the abandonment, in 1913, of the Yellow Dog a bit farther to the north, the Black Cat, Ground Floor, and Florence workings had been flooded. However, as there was no cut through from this side into the area it was proposed to exploit, it was thought that moderate pumping facilities would take care of the water. Three shafts had already been sunk to the ore horizon during the previous operations; the ground was connected by wide drifts and possibly 10 acres mined out, principally about the two southerly shafts which at surface are 8 and 13 ft. lower, respectively, than the collar of the shaft at which the new mill was built. The former mill on the lease was known as the Bohemian Girl. This mill, built in 1910, was removed after some 3 years' work. A head frame and hopper still existed at the middle shaft, sometimes known as the lower Hold Out shaft, but at the most northerly

Jan 1, 1918

By W. H. Bassett, C. Davis

Although brasses and bronzes have been made for ages, a systematic study of their physical properties has been carried out only during the years of the present century. Among these properties may be included those which are to be detected by means of microscopic examination; in other words by the science of metallography. The earlier workers in this field, both in this country and abroad, gave their attention to steel. When the senior author explored the situation in 1902, there was little encouragement to be found in undertaking the study of the non-ferrous alloys. A start was made, and the metallography of the brasses and bronzes, as well as of the copper-nickel-zinc alloys developed materially under his direction. Annealing experiments were begun in 1902, and in the succeeding years the effect of temperature, and the influence of previous working, on the grain size of brass were studied. The conclusions so well known and widely published today were largely reached during those earlier years. In 1905 the first complete annealing series were made. By this it is meant that brass and copper sheet, 5 B & S Nos. hard, was machined into tensile test specimens, then annealed under accurate control for 30 min. at temperatures up to the melting point of the material. Various determinations were made, including tensile strength and elongation in 2 in. There rapidly followed similar series on all of the copper-zinc alloys from 100 to 60 per cent, copper, on the bronzes, cupronickels, and on copper-zinc-nickel alloys. At this point there was published by Grard, in October, 1909,' the very comprehensive and complete work on the tensile properties of cartridge brass, 90-10 copper-zinc, and electrolytic copper. The excellent photomicrographs in that paper illustrated the changes in structure produced by cold rolling as well as by annealing at different temperatures, but where Grard's work was confined to copper and to two alloys, the investigations in this laboratory have been over the entire fields of the commercial copper-zinc alloys, copper-tin alloys, representative copper-nickel and copper-nickel-zinc alloys as well as aluminum bronzes and others of a more special nature.

By Charles P. Williams

The lead-bearing area of Missouri has been subdivided, geographically, into the Southeastern, the Central, and the Southwestern

By Alan Morris

Impingement attack, as one of the types of corrosion suffered by condenser tubes, has been given a prominent place in corrosion literature of recent years. It has been reproduced and studied in carefully controlled laboratory tests. Much has been learned of its mechanism, and of the effects of variables such as temperature, amount of air, size of bubble and water velocity. Incidentally the technical public has been given comparisons between the behavior of some few metals under various conditions of impingement attack. The tests recorded here were undertaken in an effort to find at least some sort of qualitative answer to questions which arose occasionally as to the relative resistance of various alloys to impingement attack, and which could not be answered by reference to the literature. The final decision to start work on the problem was influenced in large measure by the nature of the water available in this particular place. The mill of the Bridgeport Brass Co. is located on the Pequonnock River at Bridgeport, Conn., within two miles of its mouth. The water is much like many other estuarine sources which are used in condensers, and which cause particularly severe corrosion. It seemed a most suitable water to use in such tests. As the work progressed an important seasonal variation was noted. The purpose of this note is to record this seasonal effect. The results of individual tests are given only incidentally. Impingement Tests Early in 1929 the apparatus was built. The samples were disks of 1-in. dia., cut from sheet metal. They were eleaned with fine emery cloth and set in holders, as shown in Fig. 1. A stream of water pumped directly from the river impinged on the surface of the sample. Compressed air was injected into the water stream through an air duct. Water pressure was maintained at about 35 Ib. per sq. in. and air was controlled by a needle valve. Velocity of

Jan 1, 1932

POSITIONS VACANT (Under this heading will be published notes sent to the Secretary of the Institute by members or other persons.) Metallurgist wanted for research in iron and steel. Man with experience in mills preferred. Salary $4,000. No. 13. Opening for a few technical graduates to act as instructors in mining to men at the mines under the supervision of the State mine inspector. Salary $1,800 per year. No. 14. ENGINEERS AVAILABLE (Under this heading will be published notes sent to the Secretary of the Institute by members or other persons.) Mining engineer and metallurgist open for engagement, as superintendent of mines or constructing engineer. Technically educated, with 14 years' experience in United States and Latin America in concentration, amalgamation, cyaniding, constructing. Just finished building large modern all-sliming cyanide mill in Central America. No. 18.

Jan 4, 1914

By J. D. Shaw, E. B. Gebert, D. O. Noel

It is, of course, expected that manufacture of the various metal powders should involve numerous methods adapted to the specific characteristics of the metals themselves. Several methods for powdering a particular metal may be available, but the physical characteristics of the powder as produced by the several methods may be quite different. In the final analysis, the application of the metal powder dictates the physical properties that the metal powder must possess, and this, to a very large extent, will determine which of several possible methods of manufacture is adopted. Sometimes powder of the same metal is produced by more than one method, each powder having specific characteristics that make it particularly suitable for its application. For purposes of classification, the various methods of powdering metals can be grouped as follows: 1. Machining. 2. Milling (by ball mills, stamps, attrition mills, etc.). 3. Shotting (pouring molten metal into water, air, etc.). 4. Granulation (by stirring molten metal while solidifying). 5. Atomizing (disintegrating by steam, compressed air, etc.). 6. Condensation of metal vapor. 7. Reduction of oxide powders. 8. Chemical precipitation. 9. Electrolytic deposition. 10. Sintering (for producing alloy powders). 11. Formation of an alloy followed by dissolving or otherwise removing one of the alloying constituents. Machining Turnings, cuttings, filings, etc., are, of course, produced as by-products in machine work of various kinds, and find certain applications as metal powders. For example, iron powder so produced is used extensively as a reducing or precipitating agent and as a constituent in certain hard-finish cements.

Jan 1, 1938

By D. O. Noel, E. B. Gebert, J. D. Shaw

It is, of course, expected that manufacture of the various metal powders should involve numerous methods adapted to the specific characteristics of the metals themselves. Several methods for powdering a particular metal may be available, but the physical characteristics of the powder as produced by the several methods may be quite different. In the final analysis, the application of the metal powder dictates the physical properties that the metal powder must possess, and this, to a very large extent, will determine which of several possible methods of manufacture is adopted. Sometimes powder of the same metal is produced by more than one method, each powder having specific characteristics that make it particularly suitable for its application. For purposes of classification, the various methods of powdering metals can be grouped as follows: 1. Machining. 2. Milling (by ball mills, stamps, attrition mills, etc.). 3. Shotting (pouring molten metal into water, air, etc.). 4. Granulation (by stirring molten metal while solidifying). 5. Atomizing (disintegrating by steam, compressed air, etc.). 6. Condensation of metal vapor. 7. Reduction of oxide powders. 8. Chemical precipitation. 9. Electrolytic deposition. 10. Sintering (for producing alloy powders). 11. Formation of an alloy followed by dissolving or otherwise removing one of the alloying constituents. Machining Turnings, cuttings, filings, etc., are, of course, produced as by-products in machine work of various kinds, and find certain applications as metal powders. For example, iron powder so produced is used extensively as a reducing or precipitating agent and as a constituent in certain hard-finish cements.

Jan 1, 1938

By S. F. Ravitz, S. R. Zimmerely

High-grade cobalt concentrates were produced from the complex Blackbird ore with very good recovery in continuous pilot-plant operations in which a low-grade bulk cobaltite-pyrite flotation concentrate was roasted in a multiple-hearth furnace to oxidize the pyrite selectively. The cobaltite was floated from the resulting calcine.

Jan 10, 1950

By W. M. Reilly, Martin E. True, O&apos

A technique, equipment, and a compound have been developed and field tested for sealing tubing joint thread leaks without removing the tubing from the well. This eliminates the necessity of killing the well with possible damage to the producing formation, which could result if it were exposed to drilling mud. A thread sealing compound, developed and tested in the laboratory, is introduced into the tubing and squeezed into the joint to eliminate the leak. A high percentage of successful field applications have eflected an appreciable cost reduction in repairing leaking tubing strings in East Texas and in the Louisiana Gulf Coast area. INTRODUCTION In producing oil and gas wells the industry has been plagued with a never ending problem of tubing connection leakage. This situation is becoming increasingly more significant as more gas wells are placed on production and as higher pressures are encountered at greater depths of current drilling. Substantial progress has been made in minimizing thread leaks by careful handling and cleaning of joints and by the use of improved sealing compounds in combination with controlled makeup. But even with the use of the best known methods and sealing materials during initial makeup, occasional leaks through tubing joint threads appear inevitable. In some instances, tubing joints in high-pressure gas wells have been found to leak gas at relatively less pressure than that at which the tubing had been tested satisfactorily using liquid. Many expedients have been employed to prevent the physical replacement of tubing when leaks have developed. Perhaps the most commonly used is the sodium silicate treatment in which the solution is lubricated into the tubing to form a crystalline plug in the leak. Generally, any benefit realized is of a temporary nature. In addition to field studies on handling and makeup of tubing, extensive laboratory work has been undertaken on the development and testing of thread dopes.' Also, substantial effort has been devoted to testing tubing joints using high-pressure gas as a pressure medium.' The results of this work have emphasized that tubing joints are susceptible to occasional leaks, especially when subjected to relatively high differential pressures. To cope with the problem of leaking connections, an extensive investigation was undertaken to devise means of sealing leaks without removing the tubing from the well and without reducing the inside diameter of the tubing. The purpose of this paper is to present a technique, together with the associated equipment and compound, which have been developed for effecting a seal of leaking tubing in place. DISCUSSION Work was initiated simultaneously on two ventures: (1) to develop a satisfactory leak sealing compound and (2) to develop tools necessary to find the leak and place the compound. Leak Sealing Compound In the development of a sealing compound, tests were conducted on those compounds commercially available which include: (1) conventional thread lubricants, (2) thermo-setting resins and (3) other materials which held promise of effecting a seal. Although none proved completely satisfactory in their available form, two commercial compounds proved nearly equally effective in sealing leaks during laboratory tests after proportioned quantities of graded silica had been added. Field usage has indicated that the preferred compound is one prepared of an aluminum-stearate base thinned to the proper constituency and carrying a mixture of fine mesh graphite and graded silica. The compound developed by Humble Oil & Refining Co. is designated as Tubing Thread Leak Sealant 800. Placement Tools and Technique In developing tools to detect joint leaks and to place the sealing compound, work was done initially on wireline equipment. Preliminary designs were completed of a tool somewhat on the order of a pressure bomb to test individual joints with gas at high pressure to determine if the joint was leaking. An entirely different tool equipped with opposed packers was intended for placement of the sealing compound at high pressures in each leaking joint. The application of these tools

Jan 1, 1958

By P. E. Busby, C. Wells

FURTHER study of data used in determinations of 1—rates of diffusion of boron in austenite and 2—solubilities of boron in the a and phases of iron and steel' has provided an equation for the diffusion of boron in a iron. In brief, the previously published data were accumulated from the results of deboron-izing (and decarburizing) experiments carried out in the range of 700° to 1300°C. Diffusion coefficients (D?) for boron in austenite were calculated using the Grube solution of Fick's law. However, only solubility values were estimated from the discontinuous concentration-penetration curves, Fig. 1, which are characteristic of diffusion in two phases. Dr. Carl Wagner' has recently provided a solution for calculating D values from penetration curves of this type as follows: Cl1.1 —C8/C8- C11.1 = vp ? e ? erf (?) and D = ?/4?2 t where C11,12, C8, C11, and E have the values shown in Fig. 1. D is the diffusion coefficient, sq cm per sec; t is time of deboronizing anneal, see; and ? is a di-mensionless parameter. For a given diffusion experiment, the value of ? can be readily obtained by graphical solution from a plot of y vs the right-hand part of Eq. 1. D may then be evaluated from Eq. 2. The avplication of this solution to previously re-ported results, of which excerpts are given in Table I, permits the calculation of diffusion coefficients for boron in a iron. On the basis of these meager data, it is tentatively concluded that the diffusion of boron in a may be represented by the equation Da = 1011 e-92,900/RT where R is the gas constant, cal X 0C-1 X mol-1; and T is the absolute temperature, OK. Although the frequency factor, 106 sq cm per sec, is admittedly several orders of magnitude higher than expected, the value of Q, 62,000 cal per mol, appears reasonable and is, in fact, very similar to that for the self-diffusion of iron. It is pertinent to mention at this point that the value of Q obtained for the diffusion of boron in austenite by means of the Wagner solution is 19,000 cal per mol and is in excellent agreement with the value previously reported1 in the equation DT = 2xl0-3 e-21,000/RT [4] which was determined by the application of the Grube solution to other data. The fact that determined constants A and Q in the equation D? = A e-Q/RT were practically the same, independent of whether the Wagner or Grube solutions were used in determinations of D values, strengthened the authors' belief that the computed values of D (Table I) using the Wagner solution are reliable. The relative values in Eqs. 3 and 4 for the diffusion of boron in the a and ? phases, respectively, suggest that boron forms a substitutional solid solution in a iron and an interstitial solid solution in ? iron. The same tentative conclusion has been reached by McBride et al.3 on the basis of relative solubilities, atom diameter, and the size of the interstitial hole in a and ? iron. In connection with the data for test 14 listed in Table I, it is of interest to calculate the solubility of boron in a iron using the D value given by Eq. 3. As might be anticipated from the small movement of the interface in test 14, proper substitutions in Eqs. 2 and 1 give a low value, approximately 0.0004 pct B, at 850°C. Apparently at 835°C (test 13) it is possible to obtain 0.0018 pct B, and at 850°C only 0.0004 pct B into solution in the a phase before a second phase appears. These observations are consistent with the Fe-B constitution diagram proposed by McBride, Spretnak, and Speiser.3 References P. E. Busby, M. E. Warga, and C. Wells: Diffusion and Solubility of Boron in Iron and Steel. Trans. AIME (1953) 197, p. 1463; Journal of Metals (November 1953). 'W. Jost: Diffusion in Solids, Liquids, Gases. (1952) pp. 69-71. New York. Academic Press Inc. "C. C. McBride, J. W. Spretnak, and R. Speiser: A Study of the Fe-Fe2B System. Trans. ASM (1954) 46, p. 499.

Jan 1, 1955

By H. D. Wilde

At the Sugarland and Raccoon Bend fields in the Gulf Coast area, all wells are drilled with rotary tools and the casing is always set in cement that is placed by the circulation method. After the cement is set, the rotary mud that fills the hole is not withdrawn or bailed out; consequently, it is not customary to give the cementing job a direct test either by putting pressure on the hole to see whether the cement will hold or by observing whether an effective water shut-off is secured. About three years ago, this company started the practice of coring the cement left in the bottom of the casing and examining the core thus secured. If the core was hard and strong, the cementing job was judged a success but if the core was incoherent, soft, and crumbly, the job was considered a failure. Of course, there were intermediate types of cores and it was not always a simple matter from this examination to decide whether the job was a success or failure. After about two years, a summary of the core examinations that had been made indicated that of cementing jobs made at depths of 1000 ft. or less, 60 per cent.. were failures; of those between 1000 and 2000 ft., 80 per cent. were failures, and of those between 3000 to 6200 ft., 100 per cent. were failures. This sta,rtling table emphasized the need of the study of the conditions under which the wells were cemented and of adopting means to reduce the percentage of failures. In addition to these core tests, two wells gave direct evidence that the cementing jobs were not always successful. In one, a four-year-old well at Goose Creek, the casing was perforated, and when fluid was circulated some of the old cement wss brought to the surface. Most of it was powdery and the few chunks that were brought up were soft and crumbly. The other was a well at Raccoon Bend which during a blow-out brought a number of chalky, soft and crumbly pieces of cement to the surface. Suggested Explanations of Cementing Failures Efforts were made at once to explain the causes of these cementing failures. As all of the cements used were of a high grade and gave

Jan 1, 1930

By F. N. Rhines

DESPITE the large amount of study which has been devoted to the subject our present knowledge of the copper-oxygen system remains incomplete and unsatisfactory in many respects. This applies particu-larly to those regions in which solid metallic copper exists. The primary object of the present paper is the contribution of new information relative to the solid solubility of oxygen (or cuprous oxide) in copper at atmospheric pressure, together with certain observations in the low-pressure regions of the system. It seems appropriate also to present a brief summary of the outstanding previous work on the constitution of mixtures of copper with its lowest oxide in order to show the relation between the new facts and the system as a whole. The earliest recorded investigations of the copper-oxygen system are those of M. S. Lucas (1) § and of M. Chevillot(2) in 1819 and 1820. Lucas believed that liquid copper is capable of dissolving its oxide, but neither he nor Chevillot was able to furnish convincing proof of this property. It was not until 1866 that T. Graham° definitely established the existence of such a solubility. Nine years later W. Hampe(4) measured its extent and roughly outlined the copper-rich portion of the system. The first really precise examination of the constitutional relationship between copper and cuprous oxide, however, was that of E. Heyn(5) who in 1900 published a temperature-concentration diagram covering the range from 0 to 10 per cent of cuprous oxide at atmospheric pressure. Within these limits of composition cuprous oxide was found to dissolve in liquid copper, forming at 3.4 to 3.5 per cent a eutectic which melted at 1065° C. R. E. Slade and F. D. Farrow(6) extended these studies to mixtures of higher

Jan 1, 1934

By J. Y. Oldshue

INTRODUCTION The field of fluid mixing involves many different kinds of process objectives. In order to classify these objectives, Table 1 gives a listing of five basic application categories, gas-liquid, liquid-solid, liquid-liquid, miscible liquids, and fluid motion. However, each of these areas can be broken up into two different concepts one involved with uniformity of solids or liquids as a criteria, and the other involved with chemical reactions or mass transfer. The things that we would do to design a fluid mixing for solid suspension are quite different from things that we would do to design a mixer for heat transfer or gas-liquid mass transfer. Therefore, there are really ten separate mixing technologies. Each of these areas has its [ ] own principles of fluid mechanics, scale-up techniques and application experience. We will take a look at each of these areas and look at some of the ways that we can handle fluid mixing applications which.

Jan 1, 1979

WASHINGTON, D. C. HERBERT C. HOOVER, Chairman H: FOSTER BAIN, Vice-chairman DAVID WHITE, Vice-chairman HARVEY S. MUDD, Secretary-Treasurer, Room 2114, Dept. of Interior Bldg. J. F. CALLBREATH HENNEN JENNINGS E. W. PARKER T. T. READ An inspiring meeting of the Washington, D. C., Section was held at the Cafeteria of the Interior Building on Friday evening, Dec. 6, 1918. One-hundred and thirty-five members and guests attended, and Vice-chairman H. Foster Bain presided. The Committee on Nominations reported: for Chairman, Herbert Hoover; for Vice-chairmen, Frederick G. Cottrell, and F. L. Ransome;

Jan 1, 1919

By S. Usui, I. Matsuoka, H. Sasaki, J. Shimoiizaka

Depression of galena by sulfite or chromate ion in xanthate flotation was investigated by means of adsorption measurements, electron diffraction and flotation tests. Flotation of galena was depressed by sulfite ion only when galena had been oxidized; no depression took place with unoxidized clean galena. A similar behavior was found when chromate ion was used as a depressant, with the exception that the chromate ion depressed unoxidized clean galena around neutral pH. Depression was attained with galena on which xanthate still remained in appreciable amounts, indicating that the depression is not due to a decrease in xanthate adsorption. The galena surface produced sparingly soluble films under conditions in which depression of galena took place. These films were identified by electron diffraction as lead sulfite and lead chromate on oxidized galena and as chromic oxide on unoxidized clean galena. These observations in conjunction with contact angle measurements, indicate that the depressing action of sulfite or chromate ion arises primarily from film deposition resulting from the reaction between depressants and the galena surface. The thickness of the film was analyzed by means of electrochemical polarization.

Jan 1, 1976

By I. J. Demer, M. L. Holzworth, J. C. Kremer, P. A. Beck

For alloys which are in practice heat treated to obtain increased strength, such as steels, duralumin, copper-beryllium, and others, the treatment usually involves heating to a relatively high temperature. At such temperatures the grain size of the product is largely determined by grain growth. Even in metals and alloys annealed merely to relieve work hardening, recrystal-lization is generally followed by a certain amount of grain growth. Thus, effective grain size control, which is often of great practical importance in manufacturing processes, depends on the grain growth behavior of the material used. Despite its importance, grain growth has been the subject of few investigations of a fundamental nature. The term "grain growth" has been used to designate a group of related, but distinctly different, phenomena. The two most important and best known of this group are illustrated by the following example. Curve a in Fig I shows the increase of the average grain size of a copper-beryllium alloy, containing 2 pct Be and 0.15 pct Co, with increasing annealing temperature. The time of annealing was 2 hr. The grain size was quite uniform in all specimens. The results of a similar experiment with an alloy containing 2 pct Be and 0.31 pct Co are shown by curve b It is seen that for any annealing temperature below T, the grain size was smaller than. in the previous case. Grain growth became slower with the higher Co content. This "inhibiting" effect of the higher Co addition was associated with the appearance in the microstructure of fine, light blue particles of the CoBe phase. Up to temperature T, the structure of the inhibited alloy (curve b) was just as uniform as the structures represented by curve a. However, after annealing at T or at higher temperatures, the inhibited alloy showed some extremely large grains (much larger than the grain sizes developed by the uninhibited alloy with low Co content) mixed with the small grains according to curve b. The presence of these mixed or "duplex" structures is indicated in Fig I by the vertical lines branching off curve b. The type of grain growth occurring in uninhibited Cu-Be alloys (curve a) has been most frequently and best investigated in brass. This type has been designated as "normal grain growth,'' while the grain growth phenomena occurring in inhibited materials were, at times, referred to as "abnormal grain growth." However, since the latter term has been applied occasionally to the phenomenon of critical recrystallization, which also results in large grains although by an entirely different mechanism, in the present paper a different nomenclature has been adopted in order to avoid confusion. Typical of the grain growth in uninhibited metals and alloys is the continuous

Jan 1, 1949

By Michael B. Moolman

Both conventional and nonconventional process alternatives for gold recovery from cyanide heap leach solutions are discussed in terms of possible flowsheets. Conventional process alternatives include carbon adsorption and zinc dust precipitation, while nonconventional process alternatives include resin ion exchange, solvent extraction, and direct electrowinning. These strategies for gold recovery are compared on the basis of technological features and on the basis of process economics: Review of the technology status and process economics suggests that improvements for conventional process alternatives are possible and that further development of nonconventional process alternatives is warranted.

Jan 1, 1984

By Y. S. Bonillas

IRA B. JORALEMON, Warren, Ariz.-This paper has covered the situation so well that I have few suggestions to offer. Two points, however, are shown more clearly in the lower mines of the Calumet Arizona Mining Co. than in Copper Queen workings, and may be worth mentioning. The first is the usual association of high-grade primary sulphide orebodies with much larger masses of pyrite and silica, averaging less than 1 per cent. copper. The richer areas occur sometimes around the borders of the lean pyrite bodies, and sometimes entirely within them. While as yet we have not been able to find any certain reason for the location of high-grade sulphides in low-grade masses, it seems likely that the age of fracturing is one controlling feature. The first stage of mineralization, with pyrite and silica, had the effect of sealing up the rock. The later solutions, richer in copper, could pene-

Jan 12, 1916

By D. Duffey, P. F. Wiggins, F. E. Senftle

An examination of the neutron capture gamma ray method using a 252CF neutron source indicates that this technique may be feasible for process stream analysis of ores. Simulated laboratory experiments were made on iron in taconite and magnetite, and copper and nickel in their respective ores. Satisfactory analyses were obtained for 500-1000-g samples in a combined irradiation and counting time of 100 min. For large industrial size samples this time could be shortened. Based on these experiments, a set of guidelines are given for the use of the neutron capture gamma method in an industrial mill.

Jan 1, 1974