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By H. l. Burghoff, A. I. Blank

J. J. Kanter.*—The authors of this paper have demonstrated that at 500°F their alloy will elongate, under appropriately adjusted stress, one or two per cent over a period of 6000 hr. Then they show that after the alloy has so elongated, it will still elongate anothcr 40 per cent if it is tested at ordinary temperature. I should like to ask the authors how much more than 2 per cent over a period of 6000 hr. their alloy will elongate at 500°F. H. L. BuRghofE.—We do not know, because we have not carried out stress-rupture tests on this material. I believe your point concerning the desirability of stress-rupture testing is very well taken. In the material that we have subsequently tested we have not seen any signs of deterioration. We do not know how much further it is possible to go beyond the 2 per cent before finding grain-boundary separation. We have not encountered any under the conditions of the test. W. E. Kingston.†—IS this particular type of copper susceptible to strain-aging, and if so at those comparatively low temperatures, is that going to affect the shape of the curve? By strain-aging I mean the phenomena that certain ferrous alloys show in which the resistance to deformation increases suddenly during the low-temperature creep cycle, apparently due to some precipitation type of reaction, perhaps analogous to hydrogen embrittlement. H. L. BUrghoff.—I believe that this material is not subject to strain-aging of this type. It is very high in copper content, of course, nearly loo per cent. There are some very minor impurities and it carries a small amount of phosphorus, which, unless it is present as an oxide, should be in solid solution well within the solubility limits. I believe it does not precipitate

Jan 1, 1945

By T. M. Girdler

IN THESE perilous days of world- wide uncertainty, this Institute and the profession represented by it take on new importance in the economic life of the nation. I have long been impressed by the fact that the objects of the A.I.M.E. are purely professional and scientific. The country has benefited from your honorable tradition of adherence to those objectives over a period of 68 years. The Institute's policy of refraining from controversial matters - has made possible the serious, balanced, and uncolored consideration of the particular problems that come before it.

Jan 1, 1939

By C. K. McArthur

THE subject of classification is so broad that this discussion is confined to what the author believes is of prime importance in connection with proper grinding and classification. The years passed have witnessed many noteworthy changes in fine grinding and classification, which have been accompanied by a readjustment of ore-dressing flowsheets for the preparation of better ground and/or sized products at an expenditure of less power, steel and maintenance than formerly. Nowhere in the industry is more being done in the way of experimental work to lower costs than in grinding circuits, because, at best, grinding costs are high. Recent years have indicated that, on the average, finer grinding has a real application. Without careful preparation of the process feed, no operation can be highly efficient or successful. In an earlier paper, the findings of an extensive survey at representative concentrators were presented1. Also, in the year of 1935, a technical discussion was given by Dr. J. V. N. Dorr (Some Notes on Classification Trends in America) before the Chemical, Metallurgical and Mining Society of South Africa In both papers mentioned, much has been said regarding flowsheets, grinding and classification. The author is very familiar with these papers, having had considerable to do with the actual operation of the flowsheets, as well as large mills and classifiers in the work described. Some data from the second paper have been included in the following discussion. Circulating Load In this particular paper it seems advisable to deal with the classification phases of the work that to a major extent govern the success of any closed-circuit grinding unit. The question has often been asked in connection with a closed circuit: "What circulating-load ratio should be carried?" This is really an

Jan 1, 1937

By R. L. Wiegel

The generation of operating information for mineral beneficiation processes has become more sophisticated as a result of the use of improved laboratory analytical techniques, some of which provide multiple component assays, as well as the introduction and gradual industrial acceptance of process sensors for the measurement of flow, density, size, and chemical composition. In general, however, the mineral processing engineer's ability to tie together this wealth of information has not kept pace with these developments. In fact, in almost all existing plants, the metallurgical inflow-output balance, wed to indicate current process performance, is still being calculated from only a small portion of the information routinely available. There is substantial activity in the development of techniques for using all available process information to significantly improve the reliability of the metallurgical balance. While the use of these improved techniques does require access to computing facilities and a slight change in perspective on the part of the mineral processing engineer regarding the inviolability of process information, there are numerous practical benefits to be derived from their application. In addition to summarizing some of the concepts basic to these techniques, this paper describes the experience of the author in applying one of these advanced metallurgical balance techniques to a variety of pilot plant and commercial plant flowsheets during the past eight years.

Jan 1, 1983

By R. M. Brick

Segregation can occur only in cast alloys that solidify over a range of temperatures with a difference in composition of liquid and solid phases within this range (ignoring monotectic systems and chemical reactions as in rimming steels). Thus a pure binary eutectic alloy should show no segregation unless undercooling occurs for one of the solid constituents of the eutectic; e.g., chill-cast Al-I2 per cent Si alloys. The phasial condition implicitly described above—solidification over a range of temperatures with a compositional difference between solid and liquid—is found in nearly all solid solutions or combinations of solid solutions and eutec-tics, Metastable conditions of solidification of these types of alloys cause coring; i.e., a difference in composition between the center of a dendrite and its periphery. This composition gradient can be detected usually only by microscopic examination of etched structures; it is a "micro" effect. The gradient of more immediate industrial concern is that between the center of a cast section and the surface layers. This gross (macro) effect is usually deter-minable only by sampling of the casting at different points, with chemical analyses of each sample. If the compositional difference is of the same type as in coring, the first parts to freeze being enriched in higher-melting-point constituents, and vice versa, the effect is called normal segregation. When what is apparently the first part of the casting to solidify shows a higher concentration of low-melting-point constituents, the effect is called inverse segregation. These macro effects are quite separate from the micro effect, coring, yet the latter must be described first because it is an essential part of the picture. Coring Solid Solution, Ni-Cu The nickel-copper phase diagram is reproduced in Fig. Ia, in which the solid lines represent the equilibrium liquidus I, 3, 7 and solidus 2, 5, 8, and where the vertical I, 4: 8 represents a 55 per cent Cu alloy. Upon moderately rapid solidification, the first dendritic axes of composition 2 (see Fig. Ib) start to form at a temperature somewhat under I. Solidification continues by growth of the dendritic nuclei, but at temperature 4 the increment solidifying is of composition 5. The rapidity of this crystal growth prevents diffusion of nickel and copper atoms from adjusting the composition of the entire dendrite at 5, which it would be under equilibrium conditions. The average composition of a specific dendrite, or the entire solid phase, at temperature 4 might be that indicated

Jan 1, 1945

By Eric A. Nordhausen

A good deal of dialogue has been published and voiced concerning one mining regulation or another, that, according to those raising the issues, in effect shuts down or drastically reduces mine and/or mill reduction. The objective of this discussion is to there fore synthesize the various regulations affecting the uranium mining industry and attempt to realistically assess the extent of impact to yellowcake production - on both an individual and collective basis. Emphasis is placed on the later or newer permitting requirements under the Mill Tailings Act, Underground Injection Control Program, the Consolidated Permit Program, and the Resource Conservation and Recovery Act (RcRA).

Jan 1, 1980

By O. B. Buchlen, J. W. Smith

The Coal Research Bureau of the School of Mines at West Virginia University, using an experimental flotation cell designated an airlift-cyclone was able to obtain a clean coal product containing 7.64% ash with 94% yield and 97% coal recovery. This favorable performance was obtained with the experimental flotation cell operating as a simulated three-stage unit on slurry taken from the fine coal circuit of a coal preparation plant. This experimental device, consisting of a sheet metal cyclone-like unit mounted on a U-shaped uplift pipe, uses a combined flotation and cyclone action to beneficiate the minus 14 mesh partially cleaned feed product. In addition to providing comparable analytical results, the airlift-cyclone possesses other attractive features among them being a low capital expenditure, utilization of moderate plant floor space, efficient operation on high density feed slurry, and absence of moving parts. The primary shortcoming of the experimental cell is its limited capacity. The Coal Research Bureau presently has under construction a larger unit which, it is hoped, will provide the capacity and quality to establish the airlift-cyclone as a commercially feasible unit. Froth flotation of fine coal is a practice which has only recently gained wide acceptance in this country. Various explanations can be put forth for this delayed acceptance of a very selective and efficient system of coal preparation. Among these reasons would be the advent of continuous mining machines resulting in the increased production of coal fines, the change in market patterns from domestic and rail consumers who did not want fines to a predominantly utility market which normally consumes fines, and also the imposition of legal restrictions in regard to stream pollution. However, the major detriment is probably the high cost involved both in installation and operation of the flo- tation unit and auxiliary systems. These facts assume greater emphasis when considering that froth flotation installations normally process a low quality feed product. A recent estimate' of installation costs including dryers, filters, and other auxiliary equipment for a flotation system was $5000 to $7000 per ton of capacity while the operating costs, exclusive of auxiliary equipment, were estimated at 10 to 306 per ton of feed. The Coal Research Bureau of the School of Mines at West Virginia University is currently developing a simplified froth flotation cell, designated an airlift-cyclone, which may provide considerable savings in capital and operating costs without sacrificing product quality or recovery. This experimental cell consists of three primary components: 1) a vertically mounted U-shaped pipe; 2) an air injector device; and 3) an integrally mounted cyclone-like unit (Fig. 1). A feed slurry is introduced at the top of one leg of the U-pipe while compressed air is injected near the base of the other leg. The air serves both to aerate the pulp and to cause it to flow upward into the base of the cyclone unit where the floated clean coal is separated from the reject material and unfloated coal which remains in slurry. The Coal Research Bureau's experimental airlift-cyclone is somewhat similar in principle to a flotation device developed by Russian engineers in the late 1950's. In tests upon a two-stage pilot-size device, the Russians obtained very favorable cleaning efficiencies.' However, later experience with production models demonstrated that rated capacities and acceptable product quality could not always be maintained.3 Because of these limitations, Russian engineers subsequently recommended that conventional, mechanical cells be used when cleaning difficult to float slurries. Engineers at the Coal Research Bureau felt that such a device utilizing the combined actions of a cyclone and a froth flotation machine offered numerous attractive features and merited investigation. Accordingly, a small capacity experimental airlift-cyclone was designed and, with the permission of the Christopher Coal Company Div. of Consolidation Coal Co., installed in Christopher's Humphrey preparation plant near Morgantown, West Virginia.

Jan 1, 1964

By Pei-Yung Huang, C. R. Hayward

In order to understand more fully the actual state of copper lost in copper reverberatory slags, a systematic study on the various reactions between certain metallurgically important copper compounds and synthetic copper reverberatory slags was undertaken by the authors in the Massachusetts Institute of Technology from 1942 to 1945.1 This paper, being only a part of the work completed, is published first because it furnishes the first experimental evidence of the formation of copper ferrite from reactions between cuprous oxide and copper reverberatory slags. Choice of Slag Composition The choice of the composition of the synthetic reverberatory slags to be used was much deliberated. Commercial copper reverberatory slags, neglecting minor constituents, avcrage :2,3 45 to 47 pct FeO; 38 to 42 pct SiO2; 5 to 6 pct CaO; 5 to 6 pct A12O3. Since the ternary system CaO-FeO-SiO2 has been much more thoroughly studied4 and is much simpler than the quaternary system CaO-FeO-SiO2-Al2O3, it was decided to use calcium oxide only instead of calcium oxide and alumina in the synthesis of the slags. Fortunately the composition of the average copper reverberatory slag with calcium oxide substituted for alumina lies in the region of the phase diagram clarified by the investigators. A survey of the phase diagram (Fig I) suggested two compositions: (I) the composition near the invariant point S, which is made up of 46 pct ferrous oxide, 37 pct silica and 17 pct calcium oxide; (2) the composition near the invariant point K with 45.5 pct ferrous oxide, 43 pct silica and 11.5 pct calcium oxide. Composition S has the advantage that the percentages of ferrous oxide and of silica almost exactly coincide with those of the average reverberatory slags, and that of the lowest melting point (1093º ± 3ºC) in the whole ternary system. The calcium oxide content, however, obviously is high. Since we have already substituted calcium oxide for alumina, and since calcium oxide is more basic than alumina, the fulfil- slag is decidedly too basic. Composition K has a slightly higher melting point (1150O + 3OC) and a higher silica content, but this is preferred because the slag is saturated with respect to tri-dymite and thus should not corrode siliceous refractories. Besides, it is less basic than composition S. The filial slag composition, therefore, was chosen to

Jan 1, 1949

By A. Kenneth Schellinger

IF the ball mill is considered only from an energy standpoint, it can be thought of as a converter of kinetic energy into heat energy and surface energy. The law of the conservation of energy must apply to the ball mill as it does to any machine or process in nature. The heat energy output of the ball mill is apparent to any casual observer of the operating mill since the outflow pulp will be appreciably warmer than the inflow water and rock. The rock in the ball mill is crushed by shearing of its ionic bonding caused by some impact-induced stresses beyond the elastic limit. As the bonds holding the mineral crystal lattices together are ruptured, new surface area is created on each unit of which a definite number of unsaturated bonds exist. Such unsaturated energy of bonding may be termed the "surface energy," and is a potential energy figure. This created energy was withdrawn from the ball mill system and represents an absorption, or disappearance of heat. To reduce the size of the rock, surface area must be created and with it the at-

Jan 6, 1951

By Arthur F. Taggart

The following notes represent significant excerpts from a mass of records of experimental work done in the ore-dressing laborattory at the Columbia School of Mines during the years 1926 to 1928 inclusive. Classification of Experimental Work The experiments performed may be grouped for purposes of description under the following general headings: I. Collecting agents. a. A method for quantifying collecting effect. b. Coating with undissolved collecting agents (oils). c. Action of dissolved collecting agents. II. Frothing agent's. a. A method for quantifying frothing effect. b. Relation between frothing effect and chemical composition. III. Inorganic reagents. a. Methods of studying the effects of these reagents. b. Effect on slime dispersion. c. Effect on sulfides. Summary of the Origins of Present-day Flotation Practice The first practicable, foolproof method of froth flotation was described in U. S. Patent 835120, issued in 1906 to Sulman, Picard and Ballot, and in the equivalent patents in other countries. A number of less simple methods of producing the same result had been described previously in patent publications and otherwise.' The reagents specified in all of these early patents were "oils" and, in addition, some inorganic substance, usually an acid. The quantities of reagents recommended and added were enormous when compared with those used today.

Jan 1, 1930

By Cyril Stanley Smith, Earl W. Palmer

STRIP of any of the metals used for deep drawing operations occasionally yields cups that are defective because of a rim that varies in height around the cup in a wave-like manner Some such defects are traceable to tools or other press factors, but when the protuberances formed (usually four in number on brass and other copper alloys) are symmetrically disposed with respect to the rolling direction of the strip, they are invariably attributable to the metal The effect is known as "caring" and the protuberances are called "ears" Other terms frequently heard are "tips," "scallops," and "corners " It is recognized that the effect is most commonly a result of a directional crystal structure produced by rolling and annealing operations in the manufacture of the metal strip Numerous papers dealing with various aspects of the caring effect have appeared in the literature, those listed in the references' being especially interesting and valuable An investigation of the factors influencing caring of brass cups has been in progress in the laboratories of the American Brass Co for several years, and it was thought desirable to make some of the results generally available in summarized form The present paper discusses many factors that do and do not contribute to ear formation In addition, a section is devoted to methods of minimizing the caring tendency of brass sheet by proper selection of the cold-rolling and annealing schedule by which it is produced In the space available, it is impossible to quote detailed experimental procedures and numerical results However, the authors make no statement that they do not believe to be properly substantiated, either by experimental evidence obtained under laboratory conditions or by experience in the actual production of deep-drawing brass in the brass mill MECHANISM OF EAR FORMATION It must be clearly understood that the formation on cups of symmetrical ears, four or more in number, is attributable solely to the strip metal, and results from the strip having different deformation characteristics in different directions The tools used in the drawing process, or the type and completeness of lubrication of the strip, have nothing to do with the problem of ears, although they do, of course, greatly affect the "drawing quality" of the strip and the general appearance of the cup A single tip may be drawn up on the rim of a cup because of misalignment of the tools, or because the gauge of metal varies from side to side of the strip The two-ear form that sometimes appears is also traceable to gauge variations However, the four-ear and six-ear symmetrical forms that we are concerned with here are caused by factors inherent in the structure of the metal itself

Jan 1, 1942

By R. I. Jaff, H. R. Ogden, D. J. Maykuth

A phase diagram for alloys containing from 0 to 66.9 pct Mn was determined. Two compounds, tentatively labeled 6 and y, were found in this range. The 6 compound is located at about 66.9 pct Mn and melts congruently at 1330°C. The ? compound has a composition near 53 pct Mn and originates in a peritectic reaction at 1200°C between liquid and 6. ß and Y enter into a eutectic reaction at 1175°C. The ß phase field terminates in a very sluggish eutectoid reaction between a and ? at 550°C. MANGANESE is one of the important alloying addition elements to titanium. As a ß-stabiliz-ing addition for a-ß and ß alloys, it provides high strength with adequate ductility.' Two of the earliest commercial alloys contain manganese as a major alloying component.' The earliest published data on the constitution of Ti-Mn alloys was that of Wallbaum,~ who reported the existence of the compound TiMn2. The transformation range of commercial-purity Ti-Mn alloys was investigated by Craighead, Simmons, and Eastwood' who found limited a solubility and a lowering of the ß transus to about 790°C at 7 pct Mn. Preliminary work by the authors of this paper, using high-purity titanium, confirmed the ß-stabilizing action of manganese and showed the existence of several intermediate phases in the Ti-Mn system." More recently, McQuillan3 determined the ß transus temperatures for high-purity Ti-base alloys containing up through 4.4 pct Mn. These data are given in Fig. 1. The present investigation covered alloys made with a high-purity base. The constitution of titanium-rich alloys made with commercial titanium has been reported4," by Holladay, Kura, and Jackson. The alloy range covered in the present investigation was from 0 to 69.5 pct Mn. This alloy range extends slightly beyond the composition of the first congruent-melting compound encountered on proceeding from the titanium end of the system. A description of the materials and methods used in the determination of the diagram is given in the Appendix. The partial phase diagram determined for the Ti-Mn system is shown in Fig. 2. Details on equilibria in the titanium-rich alloys are given in Fig. 3. Liquid-Solid Relationships Observations on the cast structures of the arc-melted ingots showed that the terminal solid solution of manganese in ß titanium enters into a eutectic reaction with an intermetallic compound labeled ?. As will be shown later, this compound has a composition around 53 pct Mn. The eutectic reaction temperature was determined as 1175°C by thermal analysis which also showed that the ? phase originates in a peritectic reaction at 1200°C. Fig. 4 shows typical eutectic structures for alloy compositions on both sides of the eutectic composition which is located at 42.5 pct Mn. In alloys over the range of 45.4 through 69.5 pct Mn, a second intermetallic compound, labeled 6, was identifield as the primary phase. This phase consistently increased in amount as the manganese content approached 66.9 pct, and, as shown in Fig. 5, an alloy structure containing 66.9 pct Mn consisted essentially of the 6 compound. Thermal-analysis data indicate a melting point of about 1330°C for the 6 intermediate phase. At 67.0 pct Mn, small quantities of a new, higher manganese-content phase were observed in the form of Chinese-script eutectic particles. Comparison of Fig. 6a and b shows an increasing quantity of this phase as the composition was increased to 69.5 pct Mn. The formation of peritectic ? in arc-melted alloys containing 45.4 pct Mn and above appears to be almost entirely suppressed, as shown in Fig. 7a and b. This is because of the narrow freezing range available for its formation by peritectic reaction and because of the very high cooling rates obtained in

Jan 1, 1954

By M. Prats, D. G. Russell

The performance of a well in a bounded, layered reservoir with interlayer crossflow has been investigated mathematically. The system studied comprises a centrally located well in a bounded cylindrical reservoir composed of two layers of contrasting physical properties. The reservoir contains a single fluid of small and constant compressibility. In the case of a well producing at constant pressure, the production rate of the crossflow system declines exponentially after the early transient behavior dies out. For wells which produce with constant rate, the pressure-time relationship is linear following the transient. For very early production time, the production rate of the two-layer crossflow system behaves as that of the two-layer stratified system (the case in which the layers are in communication at the well only). Except for early time, in most practical cases the performance of a two-layer reservoir with cross-flow can be duplicated by that of a single-layer reservoir. The equivalent single-layer reservoir must have the same pore volume and the same drainage and wellbore radii as in the two-layer case. In addition, the equivalent reservoir must have a "kh" (permeability x thickness) product equal to the sum of the "kh" products of the respective layers in the crossflow system. If the porosity and permeability distributions are known, the production and pressure behavior of a well with and without crossflow can be predicted. From a comparison of the observed pressure or production performance of a well and the theoretical behavior, the occurrence of interlayer crossflow can be detected. INTRODUCTION When flow is possible across the bedding plane from a low-permeability layer into an adjacent layer of moderate or high permeability, the earlier depletion of the more permeable layer will cause such flow to occur. If this situation exists, the oil recovery from tight layers can be appreciable; thus, the economic ramifications of interlayer crossflow are apparent. The possible importance and extent of flow between adjacent and connected layers — whether resulting from capillary, gravitational, or viscous forces — have been the subject of considerable speculation for many years. Jacquard1 presented a rigorous analysis of the crossflow due to single-fluid expansion occurring between two adjacent and connected layers when the well produces at constant rate. His presentation was entirely mathematical, however, and no numerical results from evaluation of the mathematical solutions were presented. Our objectives in the preparation and presentation of the present paper are essentially twofold— (1) to analyze the behavior of a well which produces a single compressible fluid from a bounded, layered reservoir with interlayer crossflow, and (2) to present practical numerical results and simplified formulas to facilitate engineering analysis of reservoirs with crossflow. The constant-terminal-pressure case was analyzed rigorously, whereas the constant-terminal-rate case was treated only for semisteady-state conditions. DESCRIPTION OF THE IDEALIZED TWO-LAYER RESERVOIR The reservoir to be studied is assumed to be bounded and cylindrical in shape, with a completely penetrating well at its center. The reservoir is composed of two adjacent horizontal layers between which fluid is free to flow. Each layer is assumed to be homogeneous, isotropic and completely filled with a fluid of small and constant compressibility. The total thickness of the reservoir is small enough

By E. H. Jr. Dix

THE consideration of alloying elements for aluminum has led to a series of investigations of the equilibrium relations between aluminum and those alloying elements. Therefore, the aluminum end of the aluminum-antimony diagram has been studied. The general form of the aluminum-antimony equilibrium diagram has been worked out by Campbell and Mathews1 and by Tammann.2 Campbell and Mathews described principally the beginning of solidification. They found the curve of beginning of solidification to rise gradually from the melting point of pure aluminum to a maximum at about 67 per cent. aluminum. After a slight lowering of the curve at a little greater antimony concentration the curve again rises to a maximum at 18.4 per cent. aluminum, which corresponds to the compound AlSb. The curve then drops to the melting point of pure antimony. Tammann explained the maximum occurring at about 67 per cent. aluminum as the result of the slow formation of the single compound AlSb. The space lattice of the compound AlSb, according to Owen and Preston,3 is face-centered cubic, the antimony atoms being intermeshed with an identical aluminum lattice. Very little, if any, work has been done on aluminum alloys containing small amounts of antimony.

Jan 1, 1930

The following Nominating Committee having been already appointed and approved by the Executive Committee in accordance with authority vested in the Executive Committee by the Board of Directors, was approved by the Directors: John V. N. Dorr, Chairman, Percy G. Beckett, J. W. Hutchinson, Julian Kennedy, William H. Linney, Charles W. Merrill, and E. Gybbon Spilsbury. The question of the purchase of Liberty Bonds, as well as that of bringing to the attention of the members the advisability of the purchase of these bonds, was referred to the Finance Committee. Sixty Members, four Associates, and thirty-six Junior Members were elected. Two Members were reinstated. Eight resignations were accepted.

Jan 7, 1917

By Frederick Laist

Introduction IN a leaching process, having obtained the copper in solution, the choice of the precipitation method is influenced y the following factors: 1. Availability of precipitant. 2. Adaptability to the leaching process. 3. Final product desired. 4. Regeneration of leaching solutions. 5. Fouling of solutions. There are three general classes of precipitation methods: 1. The use of iron, scrap or sponge. 2. Electrolytic deposition. 3. The use of some gas or reagent y which the copper is obtained, usually in the form of an intermediate precipitate which requires further treatment. For example, the precipitation of the copper as Cu2Cl2 from chloride solutions, with SO2 gas. The use of iron is adapted to almost any process. It has the great advantage of extreme simplicity, and the recovery of the copper and any values present in a highly concentrated, easily treatable form. The disadvantages are the cost in isolated places, the uncertainty of the scrap-iron market, and the fouling of the leaching solutions. The latter is a serious factor, When a reagent such as salt is used in them, which makes necessary their re-use. Where applicable, electrolytic deposition is very attractive. The copper is obtained in a form directly marketable, there is a regeneration of acid amid no fouling of solutions. Unfortunately, chloride solutions do not lend themselves to electrolysis. An entirely satisfactory anode material has not yet been discovered, although magnetite, apart from being rather brittle, seems to answer the requirements fairly Well.

Jan 7, 1914

By Robert Lepsoe

IT is generally realized that in cyaniding the precipitation efficiency of zinc dust is due to the fine division or extended surface of its metallic particles; but frequently it is thought that the presence of other, metals, say 2-3 per cent. lead, is advantageous,. causing more complete precipitation. The results of testing about fifty brands of commercial zinc .dust have led to the conclusion that there is a distinct relation of precipitation efficiency to fineness and that the effect generally can be estimated by examining the size of metallic particles. The presence of lead was not found to be of any importance. SPECIFICATIONS Generally the term "97 percent. to pass a 350-mesh screen, 95-97 per cent. uncombined metallic zinc" is used by the leading European exporters. Among the many methods of determination of metallic zinc, I have found the iodine test (iodine in potassium iodide) very satisfactory and rapid. It has been controlled by the other methods, samples of the same product having been sent to three different analysts: Iodine method 98. 11 per cent. metallic zinc, Volumetric method 97.63 per cent. metallic zinc, Ledoux Co., New York Bichromate method 98.16 per cent. metallic zinc, Watson Gray, Liverpool, England Bichromate method 98.20 per cent. metallic zinc, Norway Inst. of Tech., Trondhjem

Jan 2, 1925

By H. L. Shergold, O. Mellgren

Concentration of fine quartz particles at the iso-octane/water interface has been investigated under different conditions of pH and dodecylamine concentration. The results obtained from the related studies on the effect of amine concentration and pH on the interfacial tension, adsorption density, electrokinetic potential, contact angle, and concentration of the various amine species in the system are presented. A good correlation was obtained between these different variables. It is well-known that very fine mineral particles are difficult to float in conventional flotation machines. Flotation rate studies have revealed that the rate of flotation of fine mineral particles is much smaller than that of coarser size fractions. The theories accounting for this behavior have been discussed by Arbiter and Harris1 and also Meloy.2 Theoretically, a hydrophobic fine particle might never make contact with a bubble because of the presence of an energy barrier in the vicinity of the air/water interface.' This energy barrier will have electrostatic, hydrodynamic, and Van der Waals force components. It was thought that by using an oil phase instead of air the energy barrier would be decreased so that fine particles could be concentrated at the oil/water interface more readily than at the air/water interface. The technique used involves dispersing the fine particles in water, containing the appropriate chemical reagents, and injecting a fine dispersion of iso-octane oil droplets into the pulp. After vigorous conditioning, the pulp is passed into a separating column where the oil droplets coated with a layer of mineral particles rise to the surface to form a separate layer. Air is introduced into the base of the separating column to ensure that heavy agglomerates of oil and particles report with the organic layer. This technique has been described previously4 and adopted by Lai and Fuerstenau5 who studied the alumina-dodecyl sulfonate system. The interfacial phenomena in the system composed of hematite, water, and iso-octane in the presence of sodium dodecyl sulfate have been studied and the results reported" earlier. This paper describes the results obtained from investigations into the interfacial phenomena in the quartz/water/iso-octane system in the presence of dodecylamine. The technique used in measuring the interfacial tension, electrokinetic potential, contact angle, and adsorption density were similar to those described previously? Materials Selected pieces of a high purity natural quartz, from the Isle of Man, were crushed in a laboratory jaw crusher and pulverizer. The — 52+72 mesh size fraction was retained and leached with successive washes of hot concentrated hydrochloric acid to remove iron impurities. When no iron was detected in the solution by ammonium thiocyanate, the quartz was washed thoroughly with distilled water until the conductivity of the wash water assumed that of the distilled water. Samples of 25 g of the —52+72 mesh quartz were ground for 5.25 min in an agate vibratory mill. The ground product was 100% —44 m and 57% —10 am, as determined by the Andreasen pipette. The specific surface area of the sample used for the adsorption and flotation tests was 0.94 sq m g-l. This corresponds to a mean particle diameter of 2.4 am. The —44 am quartz sample was stored under vacuum in the presence of silica gel crystals. For the contact angle determination between the three phases, quartz, iso-octane, and water, a piece of the natural quartz was ground into a block about 15 mm long, 15 mm wide, and 5 mm thick. One surface of the block was then polished by successively finer grades of silicon carbide "paper." The final polishing was conducted with alumina on a "hyprocel" paper. The polished quartz specimen was cleaned using nitric acid and ethyl alcohol followed by a wash with distilled water and then stored under distilled water. This pro-

Jan 1, 1971

By H. M. Chance

In recent years an important function of the mining engineer has been the appraisal of the value of mining-properties required by those planning consolidations of a number of' individual operations. In no field of productive industry have the economic results attainable by consolidation been more clearly shown than in the mining-regions of the United States. In many important mining-centers unification of ownership of the most valuable properties has already partially or completely been attained, and, in other districts, projected absorptions and consolidations await only favorable financial conditions for their consummation. The iron-ore districts of the Lake Superior region, the coal-mines of Colorado, of Wyoming and of Utah, the anthracite mines of Pennsylvania, the Connellsville coking-coal mines, and large areas of bituminous coal-land in Pennsylvania, in Ohio, in the Indian Territory and in other portions of the United States, are now largely controlled by a few corporations operating on a large scale, or by a number of corporations working in harmony because of an affiliation and interleaving of interests. The tact of keen financiers and the diplomacy of men of great administrative ability are the chief operative forces in conceiving and accomplishing such consolidations, but in formulating and maturing them, the services of the mining engineer are often required to supply the facts upon which they must be based. For this purpose the expert is expected to furnish full and complete reports covering the quantity of ore, coal or other mineral available, its value per ton, cost of mining and treatment, etc. In reporting upon gold-, silver-, lead-, zinc-, copper- or iron-

Jan 1, 1905

By Charles A. Ashburner

The existence of natural gas-springs in Pennsylvania and the adjoining States west of the crest of the Allegheny Mountains was known to the earliest settlers. Possibly the first gas obtained from a well was at Fredonia, Chautauqua County, N. Y., where a well was sunk on the bank of Canadaway Creek, near the Main Street bridge, in 1821, and sufficient gas obtained for 30 burners, the inn having been illuminated by the gas when General Lafayette passed through the village about 1821. In 1858 another well was drilled, which supplied 200 burners. A still larger one was drilled to a depth of 1200 feet in 1871. According to Mr. E. J. Crissey, Secretary of the Fredonia Natural Gas Light Company, the average monthly supply of these wells in 1880 was 110,000 cubic feet. Since 1859, when the drilling of oil-wells in Western Pennsyl-

Jan 1, 1886