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CONTENTS PAGE WARNER, ROBERT K.-Efficiency of Screening. Discussed by Robert C. Canby,Robert K. Warner, W. 0. Borcherdt, V. E. Flanagan 1 FAHRENWALD, A. W.-Surface Reactions in Flotation. Discussed by Arthur F. Taggart, A. M. Gaudin 7 Efficiency of Screening Discussion of the paper of ROBERT K. WARNER, presented at the New York Meeting, February, 1924, and issued, as Paper No. 1293-M, with MINING AND METALLURGY, January, 1924. ROBERT C. CANBY, Wallingford, Conn.-On page 2, the author speaks of the importance of using a testing sieve clothed with the same material as the screen being studied; does he regard this as essential? In practice, how does the screen efficiency calculated by the difficult-grain method compare with those computed by the usual undersize method? Is it possible by the author's method, to obtain a measure of efficiency that can safely be compared with that of another screen sizing a different ore? ROBERT K. WARNER.-The use of a testing sieve clothed like the mill screen being studied is desirable but not essential for routine work about a mill where the character of the feed varies little, as regards the shape of the grains and the sizing test. Close agreement in size of aperture between the sieve and the screen is, however, important if the data obtained are to be valuable to others working on a different feed. If the testing sieve is coarser than the mill screen, the efficiency will appear unfairly low; whereas if it is too fine one might get efficiencies greater than 100 per cent. because of the apparent oversize in the undersize. In either of these cases the usefulness of the difficult-grain method of calculation would be reduced. As screens wear, the undersize grows appreciably coarser so that it is desirable to test screens only when the cloth is new or else to provide testing sieves that are worn about the same amount. The futility of making efficiency observations on a. distorted or broken screen surface is obvious.

Jan 6, 1924

By Meguru Nagamori

DURING the smelting of the sulfide ores of copper, nickel, and certain other metals, a matte phase is formed. For a better understanding of the physico-chemical properties of mattes, binary systems such as Cu-S, Ni-S, Fe-S, and so forth, should be studied, especially in the vicinity of liquid compounds such as Cu2S, Ni3S2, FeS, and so forth. These compounds are relatively stable in the solid state although they can exhibit appreciable deviations from stoichiometry. With small deviations from stoichiometry there are large changes in the activity of both sulfur and metal this is a characteristic of both solid and liquid sul-fides near the stoichiometric compositions. In the vicinityof molten Cu2S,1 for instance, the activity of sulfur increases about 100 times for a 0.012 increase in the mole fraction of sulfur and, correspondingly, the activity of copper decreases greatly. In this sens the minor deviations from stoichiometry should be carefully taken into account in studies of such metal-sulfur melts. Metal-sulfur melts may be considered to have properties intermediate between metallic solutions and molten salts, i.e., neither entirely metallic nor entirely ionic. The radius of the ion sZ- is 1.84 as compared with 1.04? for a single bond covalent s.2 It is therefore inferred that when the sulfur is more ionic its partial molar volume is larger, although metal-metal, metal-sulfur, and sulfur-sulfur interactions may bring about further complexities. Thus, it is to be expected that the molar volumes, which are derived from density-composition relations, will help in resolving the structure of the melts. In this study the maximum bubble pressure method with bubbling gases of H2, H2S, and Ar, .was employed to measure the density. EXPERIMENTAL Materials. Silver of 99.95 pct purity was melted in an alumina crucible and hydrogen gas was then bubbled through the liquid for the deoxidation. In preparation of Cu2S, electrolytic copper powder (>99.9 pct Cu) was mixed with precipitated sulfur and heated to 1200°C in an alumina crucible under a hydrogen atmosphere. Mixtures having the approximate compositions FeS and Ni3S2 were prepared by heating reagent grade electrolytic iron or reduced nickel powder with precipitated sulfur under a hydrogen atmosphere. The H2S gas was of 98.5 pct purity, the impurities being mostly CO2 and CS2 which hardly contaminate the melts. Apparatus. The crucible system is shown schematically in Fig. 1. To minimize the variation of melt composition during a density measurement, the apparatus was designed in such a way that either Ar, H2, H2S, or mixtures of these gases could be used as the bubbling gas. When the melt had a high partial pressure of sulfur, H2S gas was used. When the partial pressure of sulfur was so low that oxygen might dissolve in the melt, the use of H2 was preferred. In intermediate cases, argon or mixtures of H2-H2S were used. Density of Dibutylphtalate. Dibutylphtalate was used as the manometer fluid. Relative to distilled water, the density of the dibutylphtalate, pdib g per cc, was measured and found to be: pdib (25°C) = 1.046 i 0.002. With the use of the temperature coefficient reported by Kemppinen and Gokcen,3 the following value was

Jan 1, 1970

By C. G. Rhodes, D. Kramer

High-field critical transport current density (J) measurements at 4.2 °K as a Junction of applied magnetic field (H) were made on samples of cold-rolled and annealed columbium with H parallel to J. Microscopic examination of the samples revealed a well-defined planar fiber structure produced by the cold rolling. J was found to he lower when fibers are parallel to the direction of magnetic field penetration than when they are perpendicular. This effect may he a consequence of the interaction of flux movement with fiber boundaries. THE severe changes in microstructure brought about by cold working superconductors leads to profound changes in their superconducting behavior. In particular, the ability of a superconductor to carry a transport current with zero resistance (the maximum value of this current density will be called "J" in the presence of large external magnetic fields (to be referred to as "H") is greatly influenced by the microstructure. In the case of columbium, LeBlanc and Little1 and Autler et a1.2 have observed an increase in J due to cold work. LeBlanc and Little also observed an anisotropy in J in cold-rolled columbium strips, which Hake et al.3-6 have shown to depend upon the angle between H (H ? J) and the rolling plane. An increase in J due to cold work has been found in a variety of high-field superconducting alloys3'4'7-9 as has the anisotropy effect.10 First explanations of why cold work raised J invoked the idea that dislocations carried the high-field supercurrents,8,11 since cold working drastically increases the dislocation density and presumably the number of supercurrent paths. However, recent ideas on the nature of high-field superconductivity together with new experimental evidence reveal that the bulk of certain superconductors can remain superconducting in high fields while carrying high transport currents. These later developments have been discussed by Berlin-court and Hake12 and a comprehensive review has been prepared by Berlincourt.13 According to the ideas of Gorter14 and Anderson,15 one would expect that the influence of microstructure on high-field supercurrent density will depend on tine interaction between microstructure and penetrating flux and on the direction of the Lorentz

Jan 1, 1965

By Ford R. Bryan, Edward F. Runge

BECAUSE of the need for ductile heat resistant alloys of non-strategic composition, there has been metallurgical development of Fe-A1 alloys possessing improved ductility and hot strength, together with high oxidation resistance. Iron and alu- minum form solid solutions up to approximately 35 pct Al. Alloys in the 8 to 12 pct A1 range are characterized by excellent oxidation resistance, high electrical resistivity' and, when appropriately alloyed, have creep rupture strength equivalent to that of the austenitic stainless steels.' At higher aluminum levels, the magnetic properties are of considerable interest. Nachman and Buehler" have recently reported on the desirable magnetic characteristics of the 16 pct alloy.

Jan 1, 1957

[Appalachian Petroleum Section: James M. Kimbrough, chairman; John H. Adair, first vice-chairman; Walter L. Diddle, second vice-chairman; Byron M. Finch, secretary-treasurer. Balcones Section: Robert V. West, chairman; Frank W. Jessen, first vice-chairman; Zane V. Morgan, second vice-chairman; Brantley G. Myers, secretary-treasurer. Meets 4th Wed., Petroleum Club (San Antonio) or Terrace Dining Room (Austin) Billings Petroleum Section: Charles B. Evans, chairman; L. M. Lyon, first vice-chairman; Gordon E. Lansford, second vice-chairman; Fred. A. Haddenhorst, secretary-treasurer. Meets 3rd Tues., Billings Petroleum Club. California Coastal Section: Robert L. Richardson, chairman; David K. Hayward, first vice-chairman; W. Jackson Bransford, secretary; William N. Harwell, treasurer. Meets 3rd Thurs., Pierport Inn, Ventura. Caracas Petroleum Section: Edwin A. Moo re, chairman;. Jose Cirigliano, vice-chairman; Frank B. Davis, secretary; Robert N. Powers, treasurer. Meets 2nd Tues., Caracas Theater Club.]

Jan 1, 1961

By Roscoe C. Clark

A study of the effect of various corrosive waters on five different types of cements indicated that those cements containing less than 5 per cent tricalcium aluminate were the most resistant to corrosion. INTRODUCTION Oil field experience indicates that some formation waters are excessively corrosive to some cements. A study has been made to determine the most corrosive waters and the relative resistance of various types of cement to these corrosive waters. PROCEDURE This study of the corrosion of cement was limited to an evaluation of the effect of various corrosive waters on five different types of cements. A determination was made of the types of cements which offer the greatest resistance to corrosion and of the chemical contents of waters found to be the most destructive to cements. The laboratory tests were conducted by immersing small cylinders of 20 samples of set cement in various corrosive waters. The initial mixing of most of the cement slurries was done using Tulsa tap water as the mixing water; however, a few of the slurries were mixed using a sulfate water as the mixing water. When the 20 samples had been immersed for a period of nine months, they were removed from their corrosive baths, inspected and photographed. The field tests were conducted by placing ten cement specimens, each contained in a screen wire thimble, in the gas anchors of insert pumps in wells in six different fields. The specimens were observed whenever it was necessary to pull the pumps and were returned to the 1aboratory when deterioration had reached a serious state. EXPERIMENTAL RESULTS In both the field and laboratory tests the resistance of the different cements to corrosion was determined by the condition of the samples and the number of samples of each that were in good condition at the end of the immersion period. Table I lists the various cements tested in the order of their resistance to corrosion with the most resistant at the top and the least resistance at the bottom. An analysis of Table I reveals that the upper half of the table predominates in slow set and sulphate resisting cement.: (low 3CAO.A12O3 content) while in the lower half the port-land and high early strength cements are in the majority. Of the last two the high early strength cements appear to offer less resistance to sulfate water corrosion. An investigation of the composition of the cements listed in Table I indicated that as a general rule the cements containing less than five per cent tricalcium aluminate will exhibit the greatest resistance to corrosion. The destructive action of various corrosive waters was compared by listing the waters in the order of those containing the largest number of samples that failed completely. These ratings are presented in Table II with the most corrosive waters listed first and the least corrosive last. Figs. 1 and 2 show the end views of cement samples which had been immersed in the baths of five per cent MgSO, water and the five per cent Na2SO4 water respectively in the laboratory. These .pictures are representative of the results obtained and present a pictorial evaluation of the corrosive resistance of various types of cements.

Jan 1, 1950

L. C. UREn,* BerkelEy, Cal. (written discussion).—I heartily concur with Rlr. .Fobs concerning the need for advanced courses on various phases of Petroleum Engineering. I think that his criticism is probably true of most of the engineering schools that are specializing at all in Petroleum Engineering, that is, that most of their so-called graduate courses are not of graduate caliber but are merely more specialized aspects of undergraduate subjects. It would undoubtedly be to the advantage of the petroleum profession if more advanced work could be offered in a few of the leading engineering institutions so that there would be something substantial to offer graduate students wishing to return after a period of undergraduate work, for additional training. There is no doubt but that a better trained engineer, more useful to the oil industry, could be secured from schools offering such advanced training. The problem of adpting our instruction to fit the needs of engineers trained along other lines who wish, after completion of their undergraduate work, to enter thc petroleum engineering field, is a more difficult one. It has been my experience that such men are usually sadly deficient along certain lines and that they are really not prepared for the more advanced work in Petroleum Production Engineering until they have gone back over the work which they have missed in their undergraduate training. I note that Mr. Fohs suggests that other eastern and western colleges not now stressing Petrolelim Engineering, should be encouraged to take up advanced work of this character. With this, however, I cannot agree unless the institutions arc also prepared to offer a full sequence of undergraduate work on which the more advanced courses may be superimposed. Whether or not there is a need for additional engi-ncering colleges entering the petroleum engineering field is an open qucstion. I believe that we arc turning out enough petroleum engineers at the present time and that none of the six institutions now specializing in this field arc overcrowded. Morc-ovcr, they are fairly well distributed over the country, though there may be room for an additional school in the field in the eastcrn section of the United States. F. W. Padgett, Norman, Okla. (written tliscussion).—Assuming that the stnclcnt has the proper fundamentals, that is, general science and a knowledge of the technology of the industry, then the problem is: What courses should be offered from the graduate standpoint? (a) Course Work.—His knowledge of the technology of the industry can be extended advantagcously by means of one and two-hour courses, which consist in a more detailed survey of the various branches of the industry. (b) Lilerdure.—This work may, or may not, be connected directly with his research problem. The student should become familiar with methods of locating articles in the 1iterature; should also become familiar with all the important original

Jan 1, 1928

By Charles N. Bell

The Telluride mining district of southwestern Colorado is defined by the 37" 45' and 38" parallels of latitude and 107" 45' and 108" meridians of longitude. Telluride was never a boom camp, but has had a steady growth. In recent years, notwithstanding the business depression of 1920, the business has been the same as in normal years. The first prospector is said to have appeared in 1875, in which year locations on the Smuggler vein were made. Shipments were made in 1877 and 1878, and in 1879 milling the ores was attempted. While the district produced high-grade ores, it did not become important until 1890, when the Rio Grande Southern R. R. was completed from Ridgway to Telluride. The railroad has since been extended to Durango. In the fall of 1896, 400 stamps were in operation, and the annual production was $3,000,000.00, two-thirds of which was gold. The total production from 1875 to 1923 was: gold $58,274,527; silver 41,-830,920 oz., valued at $31,016,893; copper 15,258,866 lb., valued at $2,533,291; lead 166,056,484 Ib., valued at $8,324,910; zinc 18,141,182 Ib. valued at $1,323,787; or a total production of $101,473,408. All claims are held in fee. Most of them are 1500 by 300 ft. but claims located within the last few years are 1500 by 600 ft. General supplies are obtained at Telluride, Denver, and Salt Lake. The largest mines are within 6 miles of the town of Telluride. Denver is 422 miles and Salt Lake is 439 miles, by rail, from Telluride. One-half of the distance to Denver and one-sixth of the distance from Telluride to Salt Lake is by narrow-gage railroad. The labor is efficient. The best miners are Italians and Austrians, then Slavs, Greeks, and Mexicans follow in the order mentioned. There are no labor unions. There are no serious mine pumping problems, the drainage being through adits. The Tomboy and Smuggler companies pump water from their reservoirs, the former for milling and domestic purposes and the latter for milling, power, and domestic purposes. BIBLIOGRAPHY A partial bibliography of the Telluride District is: Geologic Atlas Telluride No. 57; Preliminary Report on the Mining Industries of the

Jan 1, 1925

By C. G. Dunn

NUCLEI that are formed during the recrystallization of a grain following plastic deformation generally have orientations that differ from the original. This aspect of recrystallization may be described in terms of orientation changes. It was shown previously, in an investigation on recrystallization in silicon ferrite,1 that the observed orientation changes were highly improbable on a chance basis, and that some mechanism must be involved. Analysis showed that the data could be satisfactorily classified into the smaller of two subclassesf of the 36 third- order twin transformations. No attempt was made at that time to classify the data within the special class of 12 third-order twin transformations, although results did indicate a greater probability for some of them to occur. A classification of this type would be more valuable, of course, with more data on orientation changes per old deformed grain. The present work fulfills this condition to some degree and also extends the scope of the investigation to include the effects of original orientation and the amount of plastic deformation. The effect of original orientation is of considerable interest because of the known effects of orientation on plastic deformation, particularly with regard to degree of fragmentation and the formation of de- formation bands, and because the orientations produced by deformation should influence the orientations obtained through recrystallization. Barrett and Levenson2 reported that single crystals of iron deformed in the range 82 to 97 per cent could be put into three general classes; namely, crystals in class I maintained a reasonably sharp single orientation, those in class 2 transformed into two distinct orientations, and those in class 3 changed into a large number of major and minor orientations. Something similar would be expected for silicon ferrite crystals, and verification of this for a few cases of types class I and class 2 deformation has been reported elsewhere3 for single crystals of silicon ferrite cold-rolled in the range 10 to 20 per cent. As an example of class 2 deformation, it was shown that a crystal of silicon ferrite cold-rolled in a {110} plane in a < 100> direction developed two layers, or deformation bands differing in orientation. When this happens it is possible to etch away one band and leave a single structure for use in studying the orientation changes that occur during recrystallization. when preferred crystal orientations are obtained in recrystallization, it is notparticularly necessary to evaluate groups of common orientation, as was done previously (ref. I, Table 6); but an

Jan 1, 1946

By J. W. Harshbarger, E. L. Montgomery

The region of metallic ore deposits in northern Chile, southern Peru, western Bolivia, and northwestern Argentina occurs in arid zones at altitudes as high as 6 km (19,700 ft). Because surface water supplies are meager, new mines require unexploited sources of water. Prolific ground water aquifers occur in salar basins in this region of the Andean Highlands. Exploration water wells have been constructed and aquifer characteristics have been tested in eight salar basins. Results indicate ground water quality is good. Aquifer transmissivity and storage computed from results of pumping tests indicate maximum capacities of more than 170 L/sec (2700 gpm) for individual production water wells. Results of investigations conducted by the authors demonstrate that ground water reservoirs in the Andean Highlands comprise a source of large quantities of water for the mineral industry.

Jan 1, 1986

By E. A. G. Colls

Discusses corrosion in Trail chemical plants producing ammonia, sulphuric, nitric and phosphoric acids, ammonium phosphates, sulphate and nitrate, together with miscellaneous allied material problems and their solution using erosion or corrosion proof materials. Conclusion, that for work of this nature, most costly material may well be cheapest in the long run.

Jan 4, 1950

Jan 1, 1916

By Frederick Burbridge

The Morning silver-lead-zinc mine of the Federal Mining & Smelting Co. is about &apos;two miles northwest of Mullan, Ida. The lode is a metasomatic fissure vein. The orebody is approximately 2000 ft. long within the bounds of the property and varies in width from knife edge stringers to 50 ft. It has been developed to a depth of 3600 ft. and stands nearly vertical in Revett quartzite, which .strikes north 65" west. The high-grade veins and lenses are generally mixed with waste (siderite, quartz, and quartzite). The average grade of ore to sorting plant in 1921 was 4 oz. silver per ton, 8.6 per cent. lead, and 4.1 per cent. zinc. Wall rock stands only a short time without timbering. The minimum angle of gravity flow is 45". The ratio of waste sorted out to ore is 6 per cent. No gases are generated underground and temperature has no influence on mining operations. Fresh air is forced down the air raise and up the main shaft. Drifting and Stoping Main drifts 12 ft. wide and 13 ft. high are driven every 200 ft. (vertically) and are connected by raises 125 ft. apart. These raises consist of three compartments (chute, tramway, and timber slide) and are for the purpose of ventilation, access, and hoisting supplies to stopes. Ground is stoped between raises. Chutes are placed every 25 ft. for drawing off ore broken in stopes. Waste for filling is obtained from waste raises off the stope in walls or waste is dumped from the level above down the chute compartment of raises, which is bulkheaded so that waste can be drawn off at any floor as required. Timbering Posts and caps for square sets (varying in diameter from 6 to 24 in.) are cut to length in a sawmill on the surface. No preseratives are used. Timber is taken on a flat car along drifts to a raise nearest the working place and hoisted as required. Practically no timber is salvaged for

Jan 1, 1925

By Leon W. Dupuy

Many articles have been written describing peculiar and particular types of drilling. Little correlation has been made between the character of ground to be drilled and sampled and the type of drilling most desirable for procuring satisfactory samples. In development work, the engineer and metallurgist often desire the recovery of a sample in as physically natural a condition as possible, particularly when the sample must provide material for process tests as well as chemical and physical analyses. This paper describes the results of experimentation in drilling unconsoli-dated materials carrying titanium minerals in the Magnet Cove area, Ark. The drilling was most difficult in that the ground varied much in consistency, and it was vitally necessary to recover a physically natural sample. Ordinary churn drilling recovered a sample that could be analyzed chemically, but the sample was not in its natural state. The problem was successfully solved by utilizing and further developing methods used in the oil and clay industries. In the Magnet Cove area of Hot Spring County, Ark., the titanium minerals include rutile, brookite, ana- tase, leucoxene, and others. They occur in soil, clays, and altered rocks adjacent to novaculite in contact meta-morphic deposits. In preparing titanium minerals for use in the industry, it is necessary to know the physical characteristics of the ore. Also it is believed that the particular physical character of the titanium mineral used is just as important as the chemical character. Brookite and rutile, for example, are the same chemically but differ in crystalline structure. In preparing titanium minerals for market, beneficia-tion is necessary. For the millman to make a satisfactory laboratory test, the sample he uses must be as nearly of the same physical character as he would have from mine run ore. In the past at Magnet Cove, churn drilling had been done on the properties, and assays of total titania had been obtained. It was found, however, that the total titania was indicative merely of the presence of titania but did not tell the metallurgist the character of the material or even give him the slightest indication of what he might expect to recover. When the Bureau of Mines entered the field in the winter of 1947 and 1948, it was therefore necessary that a natural sample be recovered. LIMITATlONS IN ORDINARY PRACTICE The churn drilling that had previously been done had shown that the occurrence of titanium-bearing mineral was somewhat widespread. The samples were, however, completely beaten up and in a finely powdered state. The minerals had been slimed, and such ore dressing tests as were made from the churn-drill samples were found to be worthless. Test pitting and outcrop sampling had provided satisfactory samples of surface ore but did not represent the entire ore body. A quantity of rutile had been produced from the surface residual concentrations in the westerly part of the cove, but production ran into metallurgical trouble as depth was attained. Representative deep samples upon which ore dressing research might depend were needed.

Jan 1, 1950

By R. W. Smith, Z. Sadowski

The stabilities of finely divided mineral suspensions were determined as functions of pH and concentrations of polyethylene oxide, sodium ligninsulfonate, sodium dodecybulfate, and sodium oleate. In addition, the electrokinetic potentials of the minerals were determined under identical pH and additive concentration conditions. Flocculation or dispersion of the suspensions is discussed in terms of both the amount and manner of adsorption at the appropriate solid-liquid interface as it is influenced by additive concentration and pH.

Jan 1, 1986

Jan 1, 1917

Jan 1, 1944

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Jan 1, 1938

Jan 1, 1944

By J. C. Marquardt L., J. A. Bratt, J. P. Hunt

The Quebrada Blanca copper/molybdenum prospect lies on a dissected plateau in the high Andes of Northern Chile. The Superior Oil-Falconbridge Group began exploration of the Property in 1977 under a joint venture foreign investment agreement with the Chilean government. Quebrada Blanca is a relatively high grade secondarily enriched porphry copper deposit. Primary mineralization occurred 38 million years ago and accompanied quartz monzonite intrusive. Early disseminated Primary mineralization was followed by hydrothermal mineralization, mineralized breccia, and post-mineral faulting. After supergene enrichment Quebrada Blanca was buried under late Tertiary gravels and then partially re-exposed in Quaternary time. During the past five years, a successful exploration program has developed an open-pit mining reserve, provided samples for bulk metallurgical testing, and located more than adequate supplies of water for future operations. The main orebody is amenable to conventional metallurgical treatment and contains more than 400 Mt (441 million st) of recoverable open-pit ore at about a 1:1 overall stripping ratio. The average millhead grade during the first six years of operations will exceed 1.5% Cu, plus recoverable molybdenum values. Several hundred million tons of additional reserves are available in the surrounding districts

Jan 1, 1984