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By O. C. Wheeler

In order that the series of reports on oil and gas in Colombia may be complete, the report for the year 1941, which was not available for Volume 160 of the TRANSACTIONS, is given here. The report for 1945 begins on page 4o6.

Jan 1, 1946

By L. G. Austin

My first contact with industrial milling was during the time I worked in the electricity generating industry in the United Kingdom. In visits to power stations to investigate either deposits in the boiler furnaces or polluting deposits settling around the stacks. I had to check the performance of the vertical coal pulverizers, since poor pulverization aggravated both problems. Naturally, then, when I came to the USA in 1957 to take a PhD in fuel technology at Penn State, I was put to work to review the science of coal pulverization. After this reviewing, I was completely confused. On one hand, there was a well-developed understanding of stress-strain equations, and a rapidly developing knowledge of how stressed, brittle solids fractured, based on the Grifith crack theory. On the other hand, reading in the grinding literature gave me: -Kick's Law, which was clearly not correct in the light of modem fracture theory; -Rittinger's Law, which was also clearly not correct; -Bond's Third Law of Comminution, which was claimed to have something to do with the Grifith crack theory, but where the connection between the two was made by intuitive pseudo-scientific reasoning I could not accept; -the choice of mill motor power for the most common type of coal mill, the Raymond pulverizer, was calculated from the fan power required to move air through the mill. Although I could accept the empirical connection between the two, it made no sense from the point of view of fracture energy. Even today, most books or review chapters on size reduction start from these laws. Incorrect statements abound in the literature, such as "the Hardgrove Index is based on Rittinger's Law," which it is not, "The Bond theory states that work input is proportional to new crack tip length produced in particle breakage," which is not true, etc. My own test work showed that these "laws" did not fit the data for grinding of coal. At about this time, Epstein (1948) and Broadbent and Callcott (1956), following the original work by R.L. Brown (1941) at the British Coal Utilization Research Association, proposed describing breakage as a series of fracture stages. I took their concepts and developed the basic differential equation for a batch grinding process continuous in time, analogous to a batch chemical reactor. Robin Gardner then joined the project and did his PhD on treating batch grinding in the same way as a batch chemical reactor. He found that the basic equation had already been partially derived by Sedlatschek and Bass (1953) in Ger- many. We confirmed experimentally the validity of the equations for describing batch grinding (1962) and formulated the equation describing steady-state continuous grinding in a fully-mixed mill. At about the time this work was published, Gaudin and Meloy (1962) and Filippov (1961) independently published essentially the same equations, but without experimental proof of the validity of the concepts. I will give a brief overview of what these beginnings had led to in the design of mills for size and power, and show some of the results of this more detailed understanding of grinding processes. Concepts of Fracture Mills such as tumbling ball, rod, pebble and autogenous mills and vertical mills such as the Raymond, and E-type, apply compressive stress to lumps or particles relatively slowly. Compressive stress applied to a particle of an elastic brittle solid imparts overall strain energy to the solid and produces local regions of tensile stress, [(Fig. 1)] (Berenbaum and Brodie, 1959).

Jan 1, 1985

By Herbert K. Kutter

This paper is concerned with the physical phenomena in the fracture process of presplitting and only indirectly with the establishment of the optimum presplitting parameters. Its nature is therefore qualitative, rather than quantitative.

Jan 1, 1968

By Charles T. Baroch, Charles J. Baroch

Nuclear energy probably has greater potentialities for changing the world's way of life than any other recent discovery. The atomic-bomb bursts over Hiroshima and Nagasaki suddenly changed the concepts of war. Peaceful uses of nuclear energy are advancing so rapidly that no study of economic trends is complete without giving them consideration. The minerals specialist, especially, must be aware of this new force in our lives, as minerals and metals are essential in harnessing the new force, and atomic energy itself is rapidly improving its competitive position in the energy field. Future historians may chronicle December 2, 1942, as the beginning of the Atomic Age. On that day Enrico Fermi and his co-workers at the University of Chicago produced and controlled the first self-sustaining nuclear chain reaction. Lie many inventions, the first application of nuclear energy was as a weapon of war. However, its potential usefulness in man's work and welfare far outweighs in economic importance its destructive use in war, unless its military effect would be considered so great and all-embracing that no major power will hereafter chance a world conflict. Recognition of this potential has generated a vast international effort to exploit the atom for peaceful beneficent purposes. Like its physical manifestation, the advent of nuclear energy has unleashed chain reactions that have pervaded the political, social, and economic environments of the world. The impact of nuclear developments in one of many fields is exemplified by the uranium mining industry. Uranium was discovered in 1789 and in the next century and a half it found only an insignificant use as a ceramic coloring agent; in fact, in the latter part of that period, it was a largely unsalable by-product of the radium and vanadium industries. Up to 1940 the total quantity of uranium metal produced was not more than a few grams, of doubtful purity. Thus the production of 12,400 pounds of pure

Jan 1, 1964

By T. A. Rickard

Flaubert, as we know, laid stress on the selection of the right word, le mot juste, the precise epithet, the word that belongs to the thing. A sentence, or even a paragraph, may be spoiled by the use of a word that is not proper, that does not fit or is foreign to the meaning intended. An Australian mining expert is reported to have said: You have a property of considerable value, and what I saw warrants a good development of very rich cubicular galena, with gossan intermixed. 'Cubicular' means `belonging to a small bedroom', a `cubicle' being a sleeping compartment. He meant `cubic', of course. This is a malapropism, and reminds me of the lady from Chicago that, on her return from Europe, said how much she had enjoyed the rural parts of France, because, among other things, it was "so delightful to hear the French pheasants singing the mayonnaise to the tune of the Los Angelus". It is impossible to amalgamate coal-tar thoroughly with the pulp in the agitating-tank. In metallurgy, `amalgamate' refers to the combination of mercury with one or both of the precious metals, forming an amalgam, which is an alloy of mercury with another metal. It differs from other alloys, such as brass or bronze, in being made without the aid of heat, inasmuch as mercury is molten at the ordinary temperature. The word comes to us from the Greek. through Old French and means `something soft'. It is a mistake to use technical terms, having a specific meaning, for purposes that are foreign to that meaning. The writer of the quotation is not discussing any combination of metals; he is dealing with the physical process of mixing and is using 'amal-

Jan 1, 1931

By M. J. Pool, with Appendix by Larry Kaufman, R. W. Krenzer

Thermodynmic properties of the Cu-Mn system have been deterrrzined in the temperature range 973" to 1273°K by measuring the vapor pressure of manganese in equilibrium with alloys of compositions varying from 0.13 to 0.91 rnole fraction manganese using the Knudsen effusion technique. Activities of manganese calculated from the measured vapor pressures show large positive deviations. Calculated heats and entropies of mixing are positive with a maximum occurring at approximately 0. 7 mole fraction manganese. ThE investigation of thermodynamic properties of binary systems involving transition metals is of considerable interest at the present time. The incomplete subvalency electron levels of transition metals lead to unusual behavior in some alloys, and considerable information can be obtained by determining the thermodynamic characteristics of these systems and relating the thermodynamic behavior to observed physical properties. The Cu-Mn system, shown in Fig. 1,' provides an example of an alloy system in which the determination of the equilibrium phase diagram and various physical properties has received considerable attention, but very little work has been done on measurement of the thermodynamic properties. Elemental copper and manganese have comparable electronegatives, atomic sizes, and cohesive energies, but differ in crystal structure. They form a continuous series of solid solutions only at high temperatures and the structure varies in a continuous manner from fcc at the copper-rich end to fct at the manganese-rich end.' The purpose of this investigation was to measure the vapor pressure of manganese over a series of Cu-Mn alloys and from these values determine the thermodynamic properties of the binary system. Vapor pressure measurements were made in the temperature range 973" to 1273"K, remaining within the solid-solution region for each alloy studied. EXPERIMENTAL PROCEDURE The relative thermodynamic properties of solid Cu-Mn alloys were determined from vapor pressure measurements by means of the Knudsen effusion tech- nique. Several discussions of the theory can be found in the literature. In the case of copper and manganese, it is assumed that manganese is the only component subliming, so the vapor pressure of manganese over the various alloys can be determined directly by measuring the weight loss of the effusion cell. This is a valid assumption since the vapor pressure of manganese is about four orders of magnitude higher than the vapor pressure of copper in the temperature region of interest. The vapor pressure of manganese over the alloys at any given temperature is then related to the weight loss of the effusion cell per unit area per unit time. An upper limit of 1.5 x 10"s has been measured for the ratio of polyatomic to monoatomic molecules for manganese vapor in equilibrium with solid manganese at 1180°K, so it was assumed that manganese vapor is monoatomic. The effusion cells, fabricated from high-purity alumina, are 26 mm high, 18 mm OD, and have a wall thickness of 1 mm. Three different sized holes of 2.03, 2.54, and 3.18 mm diam were drilled in the lids from the inside face to minimize chipping, and the lids were then slip-cast onto the cells to provide a gas-tight seal. Alumina was selected for this particular application both because of its resistance to thermal shock and reaction with manganese vapor. In the ideal case, the orifice of the effusion cell should have a knife edge so that effusion through the orifice

Jan 1, 1970

By J. R. Morison, M. P. O’Brein, J. W. Johnson, S. A. Schaaf

The force exerted by unbroken surface waves on a cylindrical object, such as a pile, which extends from the bottom upward above the wave crest, is made up of two components, namely: 1. A drag force proportional to the square of the velocity which may be represented by a drag coefficient having substantially the same value as for steady flow, and 2. A virtual mass force proportional to the horizontal component of the accelerative force exerted on the mass of water displaced by the pile. These relationships follow directly from wave theory and have been confirmed by measurements in the Fluid Mechanics Laboratory of the University of California, Berkeley. The maximum force exerted by breakers or incipient breakers is impulsive in nature, reaching a value much greater than that produced by unbroken waves but enduring for only a short time interval. This impulsive force represents the ultimate development of the accelerative force and is produced by the steep wave front and large horizontal acceleration at the front of a breaker. This impulsive force greatly exceed. the drag force computed from the particle velocities of the breaker. The reader is cautioned that these preliminary results are applicable only to single piles without bracing and are likely to be modified somewhat where multiple piles are driven, one within the influence of the other or where multiple piles are connected by submerged bracing. This paper is essentially a preliminary report submitted at this time because of the current importance of wave forces in the design of offshore structures. An extended series of additional experiments is planned for the near future. Theoretical Relationships For the sake of simplicity of treatment, the theory will be developed from the equations for waves of small amplitude. The horizontal displacement of a water particle is described by the equation 2p cosh — (d + z) H L 2pt X =----------------------sin ----- . , (1) 2 2pD T sinh------ L The horizontal component of the orbital velocity is obtained by differentiation with respect to time as 2p cosh — (d + z) pH L 2pt u = ------------------- cos— .... (2) sinh- L The acceleration of the water particles at any position is obtained by again differentiating with respect to time as 2p cosh — (d + z) 9 u -2vH L 2pt -----=----------------------------sin ----- . . (3) 3 t T2 2pd T sinh------ L where H = wave height — ft L = wave length — ft d = still water depth — ft z = depth below the still water measured negatively downward — ft. T = wave period — sec t = time — sec The force exerted on a differential section, dz, in length is pD2 s u pD 1 dF= [CM (p/4) st + Cn/2 u2] dz • • (4) where D = pile diameter — ft p = water mass density — slugs/ft3 C, = coefficient of mass C,, = coefficient of drag Substituting for a s u/s t arid u2 from Eqs. (3) and (2), the force per unit length at any position z is dF p2 pD H2 &apos; / = — [- fM sin ? ± fD cos2 ? ] . . . (5) dz 2T2 fM D fD 2pt Cm = pA/H:CD = A2;? = T [+ cos2 ? for 0 < ? < p/2 cosh— (d+z) 3p L — < o < 2p Sin L -cos2 ? for p/2 <? <3p/2 The sin 9 term (inertia) i- negative for 0 < 0 < p and positive for p < ? < 2p. Values of A and A&apos; appear in Fig. 1

Jan 1, 1950

Discussion of the paper of GEORGE S. RICE and H. H. CLARK, presented at the Pittsburgh meeting, October, 1914, and printed in Bulletin No. 94, October, 1914, pp. 2563 to 2571. NORMAN V. BRETH,* Pittsburgh, Pa.-It was my privilege to visit in the last two months on behalf of the U. S. Bureau of Mines 10 mines where electric shot-firing systems controlled from outside the mine are installed. I will describe briefly what I saw in some of these mines, which are located in Utah, New. Mexico, Oklahoma, Alabama, and Kansas. At a mine in Utah, 230-volt alternating current is used to fire the shots, which is taken from a small transformer in the substation. The shot-iring circuit is independent of all other wires and is tested for grounds every day. There are no lightning arresters on the firing circuit. Porcelain insulators are used inside of the mine, and glass outside. The switches are situated as follows: One in the substation, one in, the shot-firer&apos;s cabin, two at each cross entry; where the shot-firing circuit crosses the trolley wire a switch is placed on either side of the entry in series with the shot-firing circuit. The miners are checked in and out of the mine. The coal is undercut and is shot down with permissible explosive, the shots being connected in multiple. There are 75 to 110 shots fired each day. A great many times there are no missed shots. If not more than two or three are missed they are left until next day. The fan is kept running at full speed when the shots are fired. The shot-firing switch is closed only once and the whole mine is shot at once. At another mine in Utah, power wires are used for shot-firing circuits; 500-volt, direct current is used to fire the shots. The only sizes of wire used outside of the power wires are Nos. 8 and 14 B. & S. gauge. The return is connected to the pipe lines and track. Porcelain insulators are. used inside of the mine.

Jan 4, 1915

APPROXIMATELY 3500 people thronged the Hotel Statler from February 18 to 24 for the 173rd general meeting of AIME. It was a technical extravaganza in that 82 technical sessions were held, at which 500 authors presented some 350 papers. Fortunately, Jerry Peirce, outgoing President, didn&apos;t have, to preside at all the events although after his year&apos;s stint as President, he has more than a nodding acquaintance with some of the latest problems in the mining, metals, and petroleum industries. Although the Welcoming Luncheon on Monday noon was the official opening of the meeting, Local Section Delegates and the Board of Directors convened on Saturday and Sunday, respectively. The large attendance and business like demeanor of these two groups was in accord with the energetic and competent service they have rendered the Institute through the year. To the applause of engineers and their wives who thronged the grand ballroom of the Statler for the Welcoming Luncheon, President Peirce introduced Oliver B. Hopkins, president of the Canadian Institute of Mining and Metallurgy and C. Gerow, secretary of CIM. Dr. Hopkins brought greetings from the CIM and expressed his satisfaction in the splendid spirit of cooperation that exists between the two Institutes. Dr. Hopkins is president, Interprovincial Pipe Line Co., Toronto, and counts as a close personal friend M. L. Haider, who is the 1952 President of AIME and lately of Toronto where he was a director and general manager of Imperial Oil Ltd. Mr. Haider will be known shortly as Mike to thousands of AIME members as he makes his Local Sections presidential tour. There was a pause in luncheon proceedings when Judge Harold R. Medina arrived amid the applause of the audience and somewhat breathless from his trip via motorcade from an antitrust trial against investment bankers at the courthouse downtown. With the Judge at his elbow, President Peirce took the opportunity in his introduction to good humoredly chide the Judge for the vixenish habits of public servants in their treatment of astute businessmen. The successful inventor who patents his inventions is a monopoly; the copper manufacturer who buys his competitors a drink is in collusion; but the business failure need only look to the government for a subsidy, Mr. Peirce pointed out. Judge Medina, quickly captured the admiration of his listeners. He spoke about justice, deploring partisan deals on nominations for judge-

Jan 1, 1952

Charles Catlett, Staunton, Virginia (communication to the Secretary*): I have had occasion to examine a few of the irondeposits in the immediate section of which Mr. Watson speaks, but have not had an opportunity to visit any of the well-known manganese-deposits. I find the former can be very safely read in light of the information which it is possible to get from the same measnres farther. north, where they are less completely decomposed. In the same way all of his conclusions in regard to the geology of the manganese-deposits bear out their occurrence in Virginia, when we allow for the far more complete decomposition in the section he has so carefully studied. Judging from the same measures farther north, I think he will be safe in agreeing even further with Penrose as to the origin of these ores. Some years ago I carried on prospecting work in these measures in Virginia, in which the iron-ore and manganese-ore were followed down to undecomposed material, and in which their occurrence along a definite line of stratification, and apparently a part of the original bedding, was plainly shown. This is unusual, however, even in the section of which I speak. At Crimora, Virginia, the decomposition is quite complete; at the same time the results of some hydraulic work, which has been done there, disclosed, at the time of my last visit, the manganese interbedded in the residual clay along a definite and distinct plane parallel to the bedding of the underlying quartzite, and which, as is shown at other points, corresponds with the plane of the original material. In view of the phosphorus reported by Mr. Watson as existing in the Cartersville ores, and the not uncommonly prohibitive amount in southern ores, I am interested to know whether

Jan 1, 1904

By R. F. Mehl, C. E. Birchenall

SINCE Maxwell1 first considered the self-diffusion process in 1872 its importance in the kinetic theory of matter has been recognized. Until the discovery of isotopes in 1913, a direct measurement of this quantity seemed impossible. The only information that could be gathered indirectly was for gaseous systems for which the kinetic theory was well developed. When methods of direct observation be-came available, investigations on self-diffusion were carried out in condensed phases. In metals these data are presumably of potential importance in the study of recovery, recrystallization, creep, sintering, and related phenomena. Following the pioneer work of Von Hevesy2 and his collaborators, who determined the rate of self-diffusion in lead with the naturally occurring thorium B isotope, several metals have been investigated. Pb, Ag³, Au.6,5, and Cu6,7,8,9 are examples of isotropic crystals existing in only one phase modification. Anisotropy of diffusion has been demonstrated in Bil6 and Znll. This paper is a study of a single metal in two allotropic forms and also of self-diffusion in a body-centered cubic lattice. Despite the fact that the measurements in each of the papers cited on self-diffusion in copper seem to be internally consistent to about 10 to 15 pet, the curves reported by different authors differ by factors of 2 to 4 at the same temperatures. This uncertainty may account, in part, for the failure to establish a successful correlation between the self-diffusion rates and other physical characteristics of the metals. No satisfactory theory of metallic self- diffusion has as yet been proposed to account for all the existing data and to permit estimation in other metals. Experimental Part: Two units of radioactive iron were used in these experiments, each a mixture of Fe53 and Fe59 (12). Fe53 decays by K electron capture and the emission of an X ray with a half life of about 4 years. Fe59 emits two beta spectra, one with a maximum energy of 0.26 Mev, the other 0.46 Mev, and gamma rays of 1.1 and 1.3 Mev, with a half life of about 44 days. They were present in nearly equal concentration initially. The composite half life started at about 50 days and increased as the Fe59 decayed, leaving Fe55 relatively more abundant. After aging a year, the half life was too long to measure significant decay in a month. The absorption properties also changed with time. Because of the importance of the absorption coefficient in the diffusion calculations, it was necessary to determine this quantity frequently over the period during which these experiments were carried out. This correction was unsuspected at the time of publication of notesl3 on this work and accounts for the discrepancy in alpha iron and for part of the discrepancy in gamma iron.* * The data in the present paper supersede those given in the notes entirely. In one note the scale of log D was inadvertently reversed. In addition to the correction for the drift in absorption coefficient, the D values for gamma iron at low temperatures were high owing to insuficient correction for diffusion occurring during heating and cooling through the high temperature part of the alpha range at a rate much slower than that employed in the runs reported here. The high temperature alpha rates are much higher than the low temperature gamma rates and correspond to large equivalent times at these temperatures. These experiments were discarded and new measurements taken. Independent experiments with the same activity units indicated a radioactive contaminant in the iron, but exhaustive attempts to isolate and identify it chemically failed. These experiments? indicate † These experiments will be discussed in a later publication from this laboratory. that the contaminant represented only a trace of little importance in the diffusion results. The active iron was plated from an iron chloride solution. Enough of the solution was dropped on a 1% in. square of filter paper to wet it thoroughly.

Jan 1, 1951

By R. F. Yap, N. Arbiter, C. C. Harris

A fully-instrumented driving mechanism has been constructed to study the power, aerating and solid suspension characteristics of several laboratory flotation machines. Machines operating over normal flotation speed ranges give substantially constant power numbers in liquid systems indicating that they operate close to fully baffled turbulent flow conditions. Owing to lack of geometrical scaling, power numbers for different sizes of cells of the same make are different. Even larger differences occur between cells of different manufacturers. For a given impeller, varying the tank size did not significantly affect the power consumption. Tank geometry and baffling has a slight effect on power consumption with shrouded impellers. For a given impeller speed, suspension height decreases while power increases with increasing mass of solids in suspension. While power consumption is hardly affected by particle size and clearance between the impeller and tank bottom, the suspension height significantly increases as clearance increases and as particle size decreases. Aeration was found to affect not only power but also the suspension characteristics of the machine. For closely sized particles, drastic sedimentation occurred when a critical value of the air flow number was exceeded. The critical air flow number decreased with increasing particle size. This effect was less marked with a wide particle size range. The self-aerating capacity of flotation machines increases with cell size at a given speed for the same impeller-shroud system, but decreases in the presence of frother and solids. Equations have been established for correlating all of the studied variables. Data taken from the literature were also correlated with these equations. The modern mechanical flotation machine has, over a period of 60 years, displaced other designs to become the dominant type. Once the correct chemical environmental conditions have been established, the major requirement, selective mineral-air adherence, is essentially a function of two operating variables — impeller speed and air rate. The special nature of this dependence is such that in the same apparatus, but under different operating conditions, adherence can be either prevented or destroyed. Another aspect of this observation is that flotation machines though differing in detail to a considerable extent can produce similar metallurgical results. It must be concluded that having determined the correct reagent levels, establishing the correct operating conditions are at least as important as machine design. Since about 1960, after 30 years of fairly stable circumstances, manufacturers have been developing new types of machines whose major feature is emphasis on pulp flow characteristics by virtue of new im-peller-stator designs. As far as can be ascertained, these new designs necessitate radical departures from accepted impeller speed-air rate values. Performance data are still awaited. Flotation machine development has been empirical, as is selection of operating conditions. The purpose of the work at Columbia University has been to elucidate the fundamentals of the subject so that the purely mechanical aspects of the flotation process can be understood in hydrodynamic terms.1-6 Hopefully, this might lead to intelligent selection of a particular machine and its operating conditions for a specific ore based on a minimum of testing, or even to new types of flotation machines. The present investigation is the most comprehensive to date.7,8 Earlier work, which was largely exploratory, has been repeated and extended and employes the most accurate measuring techniques available. Additionally, sufficient hydrodynamic data were obtained under flotation conditions to delineate the relevant operating ranges. Attention has been given to scaling in that several geometrically scaled tanks and impellers have been constructed and tested; it has been pointed out elsewhere that undistorted geometrical scaling rarely pertains in flotation machine design.5 This paper is divided into sections dealing with relevant combinations of the three phases: liquid, air and solid. Summaries of the literature have been given in previous publications2-4 and will not be repeated here. Recently, several reviews of mixing have appeared, which can be usefully referenced.9-11 It is of interest to note that flotation is not included

Jan 1, 1970

By Eckley B. Coxe

The subject of this paper will be treated as briefly as possible under the following heads : I. The latest designs of some of the machinery used at these collieries in the preparation of coal. 11. The means employed for elevating, conveying and transporting the coal and slate in and about the breaker. 111. The means employed for raising the coal from the mines to the top of the breaker. IV. The iron breaker as a structure. V. The preparation of the coal as effected in the iron breaker. A key to the plates and the letters and numbers designating different parts, will be found at the end of the paper. I. Preparing Coal. Anthracite coal as it comes from the mines is not marketable. The "run of mine" cannot, as in the case of bituminous coal, be sold. Anthracite, being very compact and practically free from volatile combustible matter, burns only at the surface, and it is, therefore, deemed important to have the lumps as nearly of a uniform size as possible, so that between them a large amount of surface will remain exposed to the action of the air without checking the draught too much, or allowing enough air to pass to cool the coal below the ignition-point, In other words, if the pieces of coal of the size of a chestnut and smaller are mixed with lumps of the size of an egg they fill the air-passages and prevent a free draught. It has long been recognized, therefore, that one of the most important points in preparation is to have a uniform sizing, and also to make as large a number of different sizes as can be produced without too

Jan 1, 1891

By Richard H. Mote, W. C. Schroeder

The endlessly changing pattern of mineral supply and demand offers opportunity to the alert and can bring disaster to the unwary. The discovery of ore bodies, the invention of extractive processes, the provision of new transport facilities, the political stabilization of underdeveloped areas, and many other changes can increase supply dramatically. Such new outpourings of mineral wealth from ore bodies bring fortunes to their developers, and consumers frequently find their competitive positions decidedly improved by new and cheap sources of supply. On the other hand, operators of marginal properties can find competition from newly opened high-grade mines intolerable. Consumers that have depended on the products of nearby, high-cost mines may find new, remote, low-cost supplies advantageous only to their competitors. The invention of new prospecting methods can have spectacular effects. Shortly after World War I the discovery rate of petroleum pools began to decline. The leading prospecting technique of that day, the projection downward of surface reflections of geologic structure, was proving less rewarding. Prophets foretold an oil shortage in the near future. But at that very moment scientists were perfecting the application of seismic waves to reveal underground oil-bearing geologic structures. As these geophysical methods were put into commercial use the whole outlook changed-the problem of the 1930&apos;s became how to cope with the surplus from discovery, not how to meet the ever rising demand. Many lead mines were being abandoned as unprofitable about this same time because the penalties charged by smelters for the zinc in the ores and concentrates more than counterbalanced the payments for lead and silver. Then selective flotation (at the time called differential flotation) appeared,

Jan 1, 1959

By Gieskieng, D. H.

Published tables of jaw crusher capacities are compiled for the most part from field performance data, interspersed with interpolations, extrapolations, various safety factors, and other modifications. Such a table attempts to balance and equalize field data from widely different materials, with differences of crushability, efficiency of feeding, sizing of the feed, and so on. The tests described in this paper were undertaken with the objectives of checking previously reported capacities; of studying the effects of various factors upon the capacity, including jaw plate curvature; and, if possible, of deriving a general capacity equation. Such an equation has been derived from the data obtained in these tests. It is given together with factors for its use. While more accuracy than is usually required may be obtained by careful application of the equation, it is of simple form and provides a convenient reference plane upon which the potential capacity of various crushers may be compared, and with which operating adjustments may be made on existing installations. The principal deviation in these tests from the usual approach consists of a laboratory technique which has been developed for the production of selected

Jan 1, 1949

By Henry Mackay

THE interesting paper recently submitted by Messrs. Tobelmann and Potter&apos; shows that chemical problems have developed which are of great interest in this new and important branch of metallurgy. Those who realize what a process of this kind really involves will agree that it deserves a better name than "leaching process." The word leaching conveys the idea that the copper is simply leached out of the ore with acid and then precipitated on iron; the chemistry of such a process would be of little interest. As, however, during the first year&apos;s operation of this plant 24,400,532 lb. (11,067,837 kg.) or about two-thirds of the produce, was electrolytic copper, while 7,992,033 lb., or about one-third, was cement copper, it would seem more appropriate to term the process electrochemical. It further appears, from the particulars given, that efforts have been made to have the entire production in the form of electrolytic copper. -This could be done if the chemistry of the problem were kept in balance, so that it would not be necessary to discard any solutions that carried copper and acid of commercial value. A process, such as that under consideration, in which the copper is precipitated from solution by electrolysis, the solvent being at the same time regenerated, is one that requires special chemical and electrochemical knowledge and experience if all the -copper in solution that has been extracted from the ore is to be successfully and economically produced as electrolytic copper. The object of this paper is to discuss, from the practical and theoretical standpoints, the chemical and electrochemical problems involved in the working of a process of this kind, and&apos; which must be solved to keep it in chemical and electrochemical equilibrium. In such a process, if the chemical balance is maintained, a solution can be used alternately as a

Jan 9, 1919

By George A. Guess

THE increasing demand for greater speed and more accuracy, in making daily assays of ores and products from mills treating material containing but very small quantities of lead and copper, has caused the older analytical methods to be supplanted by new ones devised to meet the needs of modern work. For " control " work in copper analyses, I had, previous to the present equipment, introduced in my laboratory the ordinary electrolytic method, using hollow cylindrical electrodes, and with these I began a series of experiments in determining the lead-content of daily mill-samples and controls. The results, proving accurate and satisfactory, I then devised, with Mr. H. E. T. Haultain, a cheaper electrode than the ordinary jacket electrode, which costs from $15 to $20,-the expense of the older form making the installation of many units very costly. The form of cathode finally adopted as the most satisfactory, shown in Fig. 1, is cut from 0.001-in. platinum foil. It is 12.5 cm. long, and is divided into a blade 4 cm. wide and 6.25 cm. long, and a tongue 0.7 cm. wide and 6.25 long, the immersion area being 50 sq. cm. and weight 1.5 grams. The blade is first sand-blasted and then corrugated lengthwise, in order to impart the necessary rigidity. Strips of platinum foil 0.001 in. thick, 12.5 cm. long and 0.5 cm. wide, having a median corrugation, form the anodes. Three electrodes are used in each cell, one anode in the middle and one cathode oil each side of the anode. These electrodes are connected to slotted alumi¬num terminals, in which they are held by contact pressure. The terminals are -in. rods, projecting 2 in. horizontally in front of the wall of the cabinet.; at the back the middle electrode (anode) is connected with one pole of the current, and the two outer ones (cathodes) with the other pole.

Nov 1, 1905

By AIME AIME

A CORPORATION would go into bankruptcy if its affairs were conducted as are those of the state of New York, according to the Committee on New York State Government Reorganization of the American Engineering Council of the Federated American Engineering Societies, in a report to the chairman, of the Joint Judiciary Committees of the Senate and Assembly. The report, just made public, was signed by the three members of the committee who were appointed by Herbert Hoover. They were H. de-B. Parsons, chair- man, Paul G. Brown and Lewis B. Stillwell. Although the American Engineering Council is a national organization, it decided to aid in governmental reorganization in New York State because of the magnitude of the task. The Council&apos;s committee in its report urged the passage of three state reorganization amendments for consolidation of departments, an executive budget system, and a four-year term for the higher state officials. In the words of the report :

Jan 1, 1921

By Arthur R. Still, Paul Gilmour

The ore deposit of the Iron King mine occurs in a group of steeply-dipping metamorphosed eugeosynclinal volcanic and sedimentary rocks of Precambrian age. Within this sequence, the ore deposit lies at the contact of a unit made up of rhyolitic tuff and interbedded andesite and a structurally underlying series consisting of andesitic tuffs, minor rhyolitic tuffs, and argillaceous sediments. Field evidence suggests that these rocks have been overturned. The ore deposit is made up of a series of overlapping, conformable or bodies consisting of massive pyrite and associated lenses of massive quartz. These contain recoverable amounts of gold, silver, lead, zinc, and copper. A parallel zone of copper mineralization occurs within the hanging-wall rocks. The deposit is considered to belong to a large and important group characterized by mineralogical composition and the lithology and structural type of the host rocks. Evidence regarding the origin of the deposit is reviewed, and it is concluded that the ore bodies were formed through the agency of volcanic hot springs on, or near, a submarine surface of deposition

Jan 1, 1968

By R. U. Fitting, A. C. Bulnes

Field experience with limestone and sandstone production indicates the existence of wide differences between the reservoir behavior of these two types of formation. Little attention appears to have been given to the separate study of the flow of fluids and the retention of fluids in limestones. This paper presents data and arguments to demonstrate the existence of a difference between the two types of formation, and urges the separate intensive investigation of limestone reservoirs. AH experimental data presented pertain to dolomitic limestone formations in west Texas and New Mexico. Two kinds of Porous media are recognized— intergranular and intermediate. Intergranular rocks are those in which the porosity and permeability are determined by the geometrical properties and the sorting of the sedimentary units; intermediate rocks, those in which there is no direct relationship between grain properties and the porosity and permeability. Limestones in general are intermediate media. The partial relationship between porosity and permeability of any class of Porous media is represelried by an area of .finite extent and definite shape on the permeability-porosity plane. The horizontal and vertical variations of porosity and of permeability in limestone and sandstone formations are discussed and compared. Comparisons are made of connate-water content, the relative permeability-saturation relationship, and capillary phenomena in the two kinds of rocks. A number of tentative conclusions are drawn relative to the reservoir properties of lime- stones; in particular, (I) dolomitic limestones are oil bearing and apparently are oil productive in zones of permeability less than 0.1 millidarcyj and (2) primary depletion (by gas expansion) oil saturations may be lower in dolomitic limestones than in sandstones. Introduction It is well known that the reservoir performance of limestones displays numerous irregularities when compared with that of sandstones, and that the departures from "normal" behavior of limestones are more frequent and generally more marked than in sandstones. This is particularly true of fractured limestones and those that have undergone considerable development of secondary porosity&apos; A review of the literature of production research published during the past 15 years reveals a startling absence of theoretical and experimental investigations directed specifically toward explaining and predicting the performance of limestone reservoirs, even. though such problems as the prediction of water encroachment and the estimation of ultimate recoveries continue at the "inspired guess" stage. By far the greater part of the experimental data reported pertain to measurements on sandstone core samples, while the theoretical studies, almost without exception, are developed from the assumption of an ideal porous medium and therefore seldom are applicable to limestone formations. The chief cause of this situation appears to be the common belief that, to all practical intents and purposes, sandstones and the majority of producing limestone formations

Jan 1, 1945