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By Thomas H. Leggett

IN speaking of the mining and economic conditions prevailing at the present time on the Rand, it is not my intention to go into the details of the mining-practice, since this has been already well described both in the Transactions1 and elsewhere,2 but rather to take a more comprehensive view of the industry and its surroundings as a. whole, marking its general development and the lines of its future progress. In a. paper entitled Deep-Level Shafts on the Witwatersrand, with Remarks on a Method of Working the Greatest Number of Deep-Level Mines with the Fewest Possible Shafts,3 presented to this Institute in August, 1900, I drew attention to the great cost of sinking the very deep vertical shafts that were then being seriously proposed as necessary for the development of the deeper areas, pointing out the strong advisability of working this ground by means of inclines to be sunk from the existing shafts of from 3,000 to 4,000 ft. in vertical depth. In this paper it is stated (1:). 975): "In short, practice upon the Rand now tends towards fewer vertical shafts and more underground inclines, especially for the very deep mining about to be undertaken." In consequence, the 6,000-ft. vertical shafts, at one time so much discussed, have never been started, and they do not now seem likely ever to be. The necessity of placing all deep shafts further apart in order to make them control and exhaust larger areas was also dwelt upon. This economy was vitally necessary for both 1 Gold-Mining in the Transvaal, South Africa, John Hays Hammond, xxxi., S17 to 855 (1901). R Engineering and Mining Journal, vol. lxxxv., p. 53 (1908). ' Trans., xxx., 947 to 987 (1900).

Jan 5, 1908

By R. F. Hehemann, S. T. Zegler

The w phase in zirconium alloys containing more than G pct Nb can form in a difjUsionless manner during quenching or with composition change during aging at temperatures below 550°C. The latter treatment establishes a metastable equilibrium between an w phase containing 5 pct Nb and a ß phase containing 45 pct Nb. The superconducting transition temperat~ire of quenched Z?-10 pct Nb and Zr-15 pct Nb alloys is increased by aging at 375°C and both alloys exhibit the same Tc after prolonged aging. The superconducting transition both in the quenched and in the aged alloys is relatively sharp (occurring ovev a temperature range of <0.5°K), and is interpreted in terms of the microstructure that characterizes the ß-w) mixture and proximity effects postulated for thin-film superconductors. At elevated temperatures alloys of the transition elements from groups 4 to 6 in the periodic table exhibit wide ranges of mutual solubility in the bcc structure. Except for compositions that are high in a group 4 element? the bcc structure can be retained at room temperature by quenching and several systematic studies of the influence of composition on superconductivity in bcc alloys have been reported.&apos;&apos;2 The high-temperature bcc form (ß) of the group 4 elements—titanium, zirconium, hafnium—is not retained upon quenching but instead transforms marten-sitically to the hcp structure (a). The Ms temperature can be lowered by alloying the group 4 metals with a solute from a higher group and with a critical amount of solute the martensitic transformation can be suppressed. The 3 phase, however, is not retained without modification. Rather, a metastable phase, w (in particular in titanium- and zirconium-base alloys), occurs over a fairly wide range of compositions above that required for suppression of the martensitic transformation.3,4 As in the formation of a, the transformation of ß to w occurs in a diffusionless manner during quenching and the temperature for its initiation (ws) is lowered by increasing solute content. The ws temperature can be well below room temperature and reversibility of the transformation allows w that forms on cooling to low temperatures to disappear again when the sample is returned to room temperature.5 In Zr-Nb alloys the w phase can also be formed during aging at temperatures below 550°c.5 In this treatment, a metastable equilibrium is established between a niobium-rich ß phase and a zirconium-rich w phase. The present study of Zr-Nb alloys was undertaken to examine the influence of microstructure: as controlled by composition and heat treatment, on the superconducting transition temperature, Tc. MATERIALS AND PROCEDURE The alloys were prepared from zirconium crystal bar that was spectrochemically pure except for 30 ppm of Al, 40 ppm of Cu, 100 ppm of Fe, and 1 ppm of each B and Pb. The niobium used was 99.5+ pct pure containing according to the suppliers&apos; (Stauffer Chemical Co.) analysis a maximum of 50 ppmO, 60 ppm of N, 30 ppm of C, 5 ppm of H, 200 ppm of Ta, 50 ppm of Mo, and 15 ppm each of Fe, Co, and Ni. The alloys were prepared in the form of buttons weighing approximately 4 g by arc melting on a water-cooled copper hearth in an inert-gas atmosphere. All alloys were heat-treated in the ß-phase region for 3 days at 1000°C and water-quenched. For heat treatment, the specimens, 0.5 cm in diam by 1.0 cm long, were wrapped in zirconium foil and sealed in an inert-gas atmosphere inside quartz capsules. Quenching was done by breaking the capsules under water. Subsequent aging treatments of Zr-10 pct Nb and Zr-15 pct Nb alloys were done by placing the specimens in a lead bath at 375°C and quenching in chilled brine. The phases present in the quenched and aged alloys were identified by optical and X-ray metallography. X-ray powder patterns were taken at room temperature with a 114.6-mm-diam Debye-Scherrer camera and CuK-a radiation. Superconducting transition temperatures were determined from magnetic-permeability measurements6 in a 10 oe field. The superconducting transition temperature was determined from a plot of galvanometric deflection as a function of temperature by extrapolation of the linear portion of the curve to zero deflection. In Figs. 1 and 3 the arrows indicate the temperature range of the transitions. RESULTS AND DISCUSSION Superconductivity in Quenched Alloys. In Fig. 1 Tc for alloys quenched from 1000°C is plotted against nominal composition. Indicated also in Fig. 1 are results of metallographic studies. Alloys containing less than 5 pct Nb transform martensitically to a during quenching from 1000°C and Fig. 1 demonstrates that Tc increases significantly as the niobium concentration in a is increased. On the basis of the Bardeen-Cooper-Schreiffer theory of superconductivity7 it seems most likely that this increase in Tc results from an increase in the density of electronic states as zirconium is alloyed with niobium. This increased density of states has been revealed clearly in low-temperature specific-heat measurements.8 The martensitic transformation to a is suppressed when the alloy content exceeds 5 pct Nb. In the range from approximately 6 to 30 pct Nb, quenched alloys consist of a mixture of B and w phases and the amount

Jan 1, 1967

By Hsun Hu, R. S. Cline

A detailed studj) of texture formation in 2 pet Al-Fe single crystals with initial orientations of approximately (111) [112], (112) [111], and (112) [111] was made by examining the textures developed on the surface and at various interior sections of the crystal after rolling to various amounts. Depending&apos; upon the initial orientation of the crystal, the surface and interior textures may differ only in sharpness, or may differ essentially in orientation. The orientation of the (111) [112] crystal does not change upon rolling up to 70 pet, but after rolling more than 90 pet a distinct component of (001) (110] orientation is developed. The texture formed in the two (112) (1111 type crystals consists of (111) (1121 and (001) (1101 components. The latter, however, is largely confined to the surface layers. The textures formed on both sides of the crystal are identical, and the texture composition profile is approximately symmetrical with respect to the central section of the strip thickness. The formation of these texture components is analyzed. DURING the past seven or eight years, deformation and recrystallization textures in rolled Si-Fe single crystals have been extensively studied by various investigators.1-7 From these studies, much knowledge on texture formation in bee crystals of various initial orientations was obtained. However, these results also raised many questions, regarding particularly the correlation between deformation and recrystallization textures, as well as the deformation texture itself of some particular crystals. To take a (111) [112] type crystal as an example, it was shown by Dunn and Koh2, 3 that this orientation does not change during deformation by rolling. This finding is consistent with the conclusion reached by Barrett and Leven-son8 with respect to iron crystals that (111) [112] is one of the stable end orientations. However, different recrystallization textures were observed by Dunn and Koh3 in (111) [112] type crystals of different initial thickness, which widened differently during rolling even though their deformation textures were identical. Another interesting example, also from the results of Dunn and Koh2&apos;3 is that of texture formation in a (112) [111] crystal. This crystal developed a two-component deformation texture of (111) [112] plus (001) [110]. Its recrystallization texture, however, was found to be predominantly (110) [001], which is related to the (111) [112] component by a simple [110] rotation. This crystal, therefore, behaved as if the other deformation texture component, (001) [110], were not present. There are also discrepancies among the results of different investigators, as well as numerous unexplained fine features of the deformation texture of crystals of various initial orientations. In order to have a better understanding of all of these points, a detailed study of deformation textures is greatly needed. One of the obvious things that has been completely overlooked in previous texture studies is the possible effect of surface texture. All past work on the texture of Si-Fe single crystals was conducted in a rather simple manner, i.e., the rolled crystals were etched to a very thin sheet; then their textures were examined by transmission X-ray techniques. For recrystallization texture studies, unless precautions are taken by etching off a sufficient amount of the surface layer before annealing, the texture developed in the interior may be affected by the surface layer, which may well have a different initial texture and which may have undergone recrystallization earlier than the interior of the specimen. Because of this effect, it is now planned to reexamine the texture of various rolled and annealed single crystals at the surface, and at various sections below the surface by using reflection techniques. In some cases, both surfaces of the rolled crystal will be examined. In one of Dunn&apos;s early papers,9 he noted that at an early stage of rolling the crystal seems to divide roughly through the middle to become a sample which in effect consists of two layers having some what different orientations. This effect has never been further explored. The investigation described in the present paper constitutes the beginning of a series of thorough investigations of texture formation in deformed bee single crystals designed to clear up some of the uncertainties which have been discussed. We have chosen a high-purity 2 pet Al-Fe alloy for this investigation. It is known that the allotropic transformation of iron is eliminated by alloying with approximately 1petAl. Such an alloy, being very similar to silicon ferrite, can be heated to the solidus temperature without phase transformation. One reason for choosing A1-Fe instead of Si-Fe for the present investigation is that we have been able to make single crystals of a vacuum-melted high-purity A1-Fe alloy by the strain-anneal method without much difficulty, but were not successful in doing so with a vacuum-melted high-purity Si-Fe alloy. For many research purposes,

Jan 1, 1962

By M. Kaitz

A continuing discussion in both the petroleum engineering and economic literature is directed to the difficulties encountered in the use of discounted cash flow rate of return (DCF) as a measure of investment worth. Although useful in most Instances, DCF has been criticized because it is time-consuming in its trial-and-error solution, theoretically invalid, not adaptable to cash flow streams yielding multiple return solutions and not entirely reliable in selecting between mutually exclusive investments. The theoretical invalidity of DCF stems from the reinvestment assumption implicit in the calculation that earnings are reinvested at the DCF rate. The emerging consensus of the economic literature is that the net present value or the present worth of the net cash flow stream (discounting at the average opportunity or cost of capital rate) is more correct and reliable. Other criteria proposed have been ratios of net present value divided by initial investment or by present value of all investments in a project. All of these criteria are simple to determine and explicitly assume a reinvestment rate for [he income generated by a project. This paper develops and discusses a theoretically valid profitability criterion which is simple to compute and retains the appeal of a percent return on investment. It is called "percentage gain on investment" or PGI. It measures the gain an investment is expected to realize over like capital invested in the average opportunity and explicitly considers reinvestment potential. Why add another Concept to the large array of investment criteria now available, any one of which, or perhaps a combination of several, appears to embrace the form&apos;s (or individuals) objectives? The answer is that not one of the existing criteria provides both a readily comprehensible and theoretically valid measure of risk coverage that has general application. The proposed PGI does fulfill these requirements. INTRODUCTION An ancient expression warns that "one must yield to the times" — there are better ways of doing things. A review of the petroleum engineering and economic literature on one topic alone, measurement of investment worth, certainly is witness to this truth. In use for a number of years, the DCF has recently received attention, directed mainly to its theoretical invalidity. Several alternatives to DCF have been proposed to provide a valid, simply determined criterion to describe investment worth and to overcome the criticisms previously mentioned. This paper introduces another method called percentage gain on investment (PGI) and is proposed as but one of several yardsticks that should be used in making investment decisions. MEASURES OF INVESTMENT WORTH This paper will consider only those criteria which give weight to the time pattern of future earnings. These criteria are usually compared with an average opportunity rate or cost of capital of the firm to judge the relative worth of the investment. For purposes of demonstration, a 9 percent average opportunity rate will be used throughout this paper. Implicit in the DCF calculation is the assumption that earnings are reinvested at the DCF rate. Some argue, though, that there is no reinvestment assumption,&apos; that the DCF rate is simply that maximum rate of interest one can pay on the investment over the life of the project and break even. The determination of DCF is accomplished by discounting the net cash flow stream at that rate (DCF) which will yield zero. The question is: why should reinvestment potential be explicitly considered in calculating return on investment or other criteria measuring economic worth? Perhaps the answer lies in consistent or equal treatment of future cash flow. It appears entirely illogical to give different present worth value to $1 received, say, 10 years from now, which is the circumstance resulting in comparing projects with different DCF returns. In fact, $1 received in 10 years has the same value regardless of which project generated the income. DCF return thus favors investment projects which are expected to provide early income as compared to those providing long-term income. Not surprisingly, the controversy on reinvestment assumption is an old one. Hoskold&apos; discussed this same problem in 1877. He considered the future income from mineral properties as an annuity or a series of fixed future payments. (As will be demonstrated, his equation can be modified for variable income.) Prior to Hoskold, the value or what one could pay for the mine, was determined with the use of standard, single-interest tables. Here is what Hoskold said with regard to these tables. "This table, and others of its kind, to be found in most works on annuities, is constructed correctly according to

By H. L. Bridgman

The correct sampling of ores is a subject of far greater importance than is usually conceded to it. Of the little which has been published on this subject, the recent paper by Mr. Glenn, with the accompanying discussion by Dr. Raymond (Trans., xx., 155), is the latest and best, and well worthy the careful perusal of all interested in accurate sampling, whether by hand or by machine. It is doubtless true that thorough hand-sampling gives as good average results as can be obtained; but all hand-sampling is subject to the possible incompetency, carelessness, or dishonesty of the workmen employed. It is, moreover, tedious and expensive, requires large space, and usually entails considerable delay, both in unloading and in sampling. For these and other reasons, machine-sampling is now regarded with more favor than ever before. So-called machine-sampling may be accomplished in two radically different ways: 1. Part of the stream of material is taken for the whole time. 2. The whole stream of material is taken for part of the time. Under the first case the stream, as it issrles from the deliveryspout of the crusher, is cut continuously in any given proportion, such as one-tenth, one-fourth, or one-half, by some fixed apparatus, which, as it contains no moving parts, is strictly speaking not a machine at all, but may be termed an appliance. The principle under which these appliances operate is now pretty generally conceded to be wrong, becanse of the practical impossibility of&apos; cutting such a

Jan 1, 1892

[NORTH AMERICA UNITED STATES ALABAMA Birmingham CORD, Richard H DISMUKES, Edward B Citronelle PERRIN, Huey P Fairfield PAGEL, Herbert Ervin Huntsville ENG, Harvard KELLEY, Dean W WAGGONER, J B Mobile HORNER, William L PETROUTSON, Peter C Montgomery GAMBLE, Halbert R Redstone RAWLINGS, William E Tuscaloosa MASON, William L University CUDWORTH, James R JONES, Walter B]

Jan 1, 1961

THE SOUTHWEST MINING SECTION of the National Safety. Council held a well attended two-day conference at Globe, Ariz., March 19 and 20; followed by two days of mine-rescue maneuvers at the Old Dominion mine in cooperation with the Globe-Miami District Mine Rescue and First Aid Association and the U. S. Bureau of Mines. C. L. Colburn of the Bureau had general charge of the arrangements and was chairman of the conference. All sessions were held in the Old Dominion Library. The program of papers was as follows: MINE FIRE PREVENTION AND FIGHTING What to do in Case of a Mine Fire. / Chas. A. Mitke, Consulting Mining Engineer, Bisbee, Ariz. Gunnite as a Fire Preventative. W. C. Browning, General Manager, Magma Copper Co., Superior, Ariz. Chemical Engineer&apos;s Part in Fire Fighting. Dr. L. H. Duschak, Consulting Chemical Engineer, San Francisco, Cal. Mine Fire Drills. A. C. Stoddard, Chief Mining Engineer, Inspiration Consolidated Copper Co., Inspiration, Ariz. Notes on the Installation of Fire Fighting Equipment in Mines. Benjamin F. Tillson, Assistant Superintendent, New Jersey Zinc Co., Franklin, N. J.

Jan 5, 1923

By J. N. Sicking, F. H. Brinkman

A new method for obtaining equilibrium vaporization ratios (K-values) for reservoir fluids has been developed and tested. By application of the method, complex experimental measurements of liquid and vapor phase compositions are eliminated. This simplified technique reduces the cost of experimental equilibrium-ratio data for reservoir studies of condensates and volatile crude-oil systems. The method is designed for systems of constant composition and, therefore, is best suited for depletion studies where compositional changes at high pressures are minor. The basic data required, in addition to the composition of the initial reservoir fluid, are the relative vapor-liquid volumes and densities at reservoir temperature and variom reservoir pressures. Tests demonstrated that the method predicts equilibrium ratios accurately for condensates. A single test on a crude oil was not conclusive; further testing will be necessary before the accuracy of the method can be determined for crude-oil systems. In addition to determining equilibrium ratios, the calculation method provides information on the physical properties of the "plus" component in the vapor and liquid phases. The "plus" component is that mixture of components heavier than the least volatile fraction analyzed. This information is useful in studies of both natural depletion and cycling operations for condensate reservoirs where the heptanes-plus component in the gas phase is produced from the reservoir. INTRODUCTION As more volatile oil and condensate reservoirs are found, the use of phase behavior techniques to predict their performance is increasing in importance. These techniques have long been used for condensate fields and have more recently been applied to crude-oil fields containing oils of medium-to-high volatility. In these phase behavior methods, equilibrium ratios (K-values) are used to predict compositional changes in the reservoir fluids—thereby accounting for the recoverable oil that exists in the gas phase. The reliability of the predictions depends to a large extent on the equilibrium ratios used. These values must be obtained for each component for the entire pressure range being investigated. Unfortunately, because of the complex nature of hydrocarbon mixtures, accurate K-values are hard to obtain. The equilibrium ratios for a particular component will vary not only with the temperature and pressure, but also with over-all composition of the system. The importance of composition is quite critical at elevated pressures, but becomes negligible at pressures below about 300 psia. Therefore, because most phase behavior problems involve the high-pressure region, each fluid system becomes a special case. Experimental programs to determine characteristic K-values are quite difficult and time-consuming. Thus, it is often necessary to resort to approximations of the K-value data. Charts giving K-values for various mixtures and classes of mixtures are available in the literature. However, there are two major difficulties in using them: (1) the K-values of the "plus" component (that mixture of components heavier than the last one analyzed) must be obtained by extrapolation from the K-values of the other components; and (2) the K-values obtained must finally be adjusted by trial and error to agree with observed volumetric data. To eliminate these difficulties, a new method of determining equilibrium ratios was developed. Briefly, after the composition of the system as a whole has been analyzed, the method uses empirical correlations and the gross fluid properties of the system (relative vapor-liquid volumes and densities) to calculate K-values. Because the calculative procedure is long, it is best solved on a digital computer. About one hour of machine time on an IBM 650 computer is required to develop a K-chart for the fluid being examined. DEVELOPMENT OF THE METHOD OF OBTAINING K-VALUES Equilibrium ratios are defined as the ratio of the mole fraction of a component in the vapor phase to its mole fraction in the liquid phase. This statement is expressed in Eq. 1. A typical plot of equilibrium ratios for a particular system is shown in Fig. 1. It should be noted that, at pressures near the saturation pressure, the K-values appear to converge to a common point. This apparent convergence point is called the convergence pressure and is a characteristic of the system involved. Various empirical correlations of K-values have been noted. It has been observed that an isothermal plot of

By A. G. Starliper, H. Kenworthy, A. Ollar

Vapor pressure determinations were made on synthesized germanium sulfides. Germanium and cadmium were removed from sphalerite concentrates by fuming. The fume was retreated to separate some of the cadmium from the germanium and, at the same time, upgrade the germanium to more than 5 pet content. MANY sphalerite concentrates contain certain impurities which have economic value as byproducts. These may include the volatile sulfides of germanium, cadmium, and lead. The objectives of the research reported in this paper were to study the fundamental volatility characteristics of germanium sulfides, to increase the recoveries of ger-

Jan 1, 1957

By Eugene N. Cameron

Pegmatites occur in abundance in certain areas of South West Africa and in adjacent parts of northern Cape Province in the Union of South Africa. Some of the pegmatite deposits were prospected before World War I, and intermittent mining was done during the period between the two World Wars. The deposits of the Jooste lithium mines became an important source of lepidolite, and beryl, columbite-tantalite, wolframite, and other minerals were produced. Since World War I1 prospecting and mining have been carried on vigorously, with the result that South West Africa produced nearly 3000 tons of beryl during 1949 through 1953, together with more than 40,000 tons of lithium minerals, chiefly lepidolite and petalite. Small amounts of tantalite, columbite, and other minerals have also been produced during the postwar period. Most of this mineral production has come from two pegmatite areas roughly outlined in Fig. 1. One is the Karibib-Omaruru area of north central South West Africa. The second is the northeastern part of the Orange River pegmatite area, which extends into adjacent parts of Namaqualand, in northern Cape Province of the Union of South Africa

Sep 1, 1955

By A. Hansson, G. E. Tardiff

WHILE it is generally known that cold-worked low-and medium-carbon steels exhibit substantial increases in tensile rupture ductility with increased deformation velocity172 (up to the von Karman limit), the observations for annealed or normalized steel do not permit simple generalization. Various investigators, for example, have reported both small increases1,3 and small decreases4,5&apos; in rupture ductility with increased rates of deformation of normalized low-carbon steel. The purpose of the present note is to report on the dependence observed for strain-aged steel since preliminary work here indicates that strain aging results in the development of a consistent type of behavior that is understandable in the light of current knowledge of the lower yield dynamics for steels which deform inhomogeneously.6 This realization throws additional light on the influences responsible for the behavior of normalized steel. The results presented here were obtained for a 0.21 pct C, 0.012 pct N sheet (0.012 in. thick) steel which was received in a temper-rolled condition (approximately 3 pct reduction in thickness after process annealing); the as-received material had a spherodized structure with a ferritic grain size of ASTM 8. The material was selected for testing after 6 months room temperature aging, at which time the static lower yield and ultimate tensile strength measured 79 and 82 kpsi, respectively. ASTM 2-in. reduced section, 1/2-in.-wide specimens were used in smooth bar tests and 3/4-in.-wide specimens containing two 60-deg opposed edge notches (root radii = 0.002 in.) were used in notched bar tests. To facilitate strain measurement, the smooth bars were blued with ink and marked at 0.1-in. intervals along the gage length; the notched

Jan 1, 1968

By Donald H. McLaughlin

THE primary function of the mining engineer is to find mineral deposits and fuels in the accessible rocks of the earth and to recover them for the vast needs of our complicated civilization. On him has been placed the responsibility for the exploitation of the nation&apos;s and world&apos;s mineral resources. The degree to which the minerals of the earth have been utilized serves to an extent as a measure of man&apos;s material advancement, as well as an index of the relative strength of nations. The natural endowment of lands, varies greatly, but the intellectual energy of a people is revealed by the way in which they take advantage of their heritage of minerals or reach out to less developed regions by exporting their engineering skill as well as capital to secure the raw materials they need.

Jan 2, 1953

By H. Y. Yancey, B. M. Bird

During the past four years the experimental work in coal washing carried on by the U. S. Bureau of Mines and the University of Washington has been devoted mainly to the development of special methods for the tabling of fine sizes of coals that are difficult to wash. One important outgrowth of this investigation has been the application of hindered-settling classification to coal tabling. Although used for many years in ore dressing, the term "classification" as used here may be new to many readers. It may be defined as the separation obtained when a bed of particles is held in a uniform state of suspension in an upward current of water, either continuous or pulsating, just sufficiently strong to keep the bed in a mobile condition. A common example of this type of separation is a jig in which there is no suction stroke. When the hindered-settling classifier is used with the coal-washing table, the fine-size raw coal, instead of being fed direct to tables, as is the prevailing practice, is first fed to the classifier and grouped, according to the rate of settling against the upward current of water, into perhaps six separate products. After dewatering, each of these except the sixth, a refuse product, is elevated to a seperate feed bin arid washed on a separate table. This paper gives a brief discussion of the basis for the use of hindered-settling classification of a table feed; a description of the experimental work; a comparison of the results obtained with and without classification; and a discussion of the application of the classifier in commercial coal washing. Basis for Use oF Hindered-settling Classification of Table Feed Although theoretical reasoning might be used to justify treating a table feed by hindered-settling classification,l the simplest method of demonstrating the need of such a step before tabling is to show the

Jan 1, 1930

The history of surface mining is essentially that of mining coal, copper, and iron ores and the non- metallic minerals, i.e. clays, gypsum, phosphate rock, sand, gravel and stone. The accompanying table comparing world production with that of the U. S. indicates that two thirds of the 8.8 billion tons of ores mined throughout the world come from surface operation. Assuming that the stripping ratio for surface mining in the U. S. applies equally to world production, then over 21 billion tons of waste, or a total of nearly 27 billion short tons of material are mined annually in the world by surface methods. Several factors are significant indicators of economic and technologic trends in surface mining. Among these are increasing production, a shift in emphasis from underground to surface mining, a decline in the grade and quality of some crude materials and, with few exceptions, an increase in the productivity of labor.

Jan 10, 1967

By John T. Dickman, Ralph E. O’Dette

Chemical Abstracts Service (CAS) is in the process of evolving a computer-based information system which will process all of the material selected for abstracting in the area of chemistry and chemical engineering and its related fields such as the earth sciences and technologies. This system is already operational to some extent and is expected to be fully utilized by 1971. The objective of CAS is to make chemical and related information more readily available, more usable and more used. Chemical Abstracts handle some 5000 abstracts weekly from 13, 000 journals and patents from 25 nations. These cover all of the 80 CA subject sections which relate to chemistry and also extend into areas of interest to geologists, mineralogists, and mining engineers. In this way, CAS fulfills its objective of complete coverage of its major fields, informative abstracting, and indexing to maximum specificity. The concept of a computer-based information system is that of a single machine-language data base into which the results of intellectual analysis of the literature are entered and from which computer programs produce a variety of publications and services applicable to the needs of a wide range of users.

Jan 1, 1969

By M. E. Wadsworth, L. H. Raby, A. S. Peck

Infrared spec troscopy was used to study the adsorption of oleate collector on three varieties of hematite. Each of the minerals was found to react with either oleic acid or a solution of sodium oleate to form a mineral cation-collector anion chemisorbed layer at the solid-liquid interface. The chemisorption reaction displaced surface hydroxyls and was found to be pH dependent. The infrared band characteristic of the antisymmetrical C = 0 structural group of chemisorbed oleate appears between 1520 and 1540 cm-&apos;. Evidence is presented which shows that molecular filming of the mineral surfaces with un-dissociated oleic acid precedes chemisorption. Infrared absorbance is correlated with the flotation behavior of the mineral. Adsorption processes are usually classified into two types which are distinguished and character- ized by the nature of the bond formed between the adsorbate and adsorbent. The process in which molecules chemically bond to solid surfaces is termed activated adsorption or chemisorption. If only weak van der Waals forces bind the molecules to the surface then the process is termed physical adsorption. Chemisorption is of primary interest in flotation systems since selectivity may be obtained if a single mineral is rendered air-avid by a specific collector mineral adsorption reaction. In previous studies infrared spectroscopy was used to define the mechanisms involved in the adsorption of oleic acid and sodium oleate on fluorite, barite, and calcite. Infrared techniques were particularly useful since adsorbed monolayers were identified in situ. Further, the infrared method permitted identification of reaction products in the solid, liquid, and vapor phases of the systems. The chemisorption reactions displaced F- from fluorite, SO4 from barite, and CO3 from calcite. This investigation was pursued in an effort to characterize and interpret the adsorption processes for synthetic hematite, compact red hematite, and specular hematite (crystalline hematite). Adsorption tests were performed using either oleic acid or

Jan 1, 1967

(Members are urged to send in for this column any notes of interest concerning themselves or their fellow-members) The following is a partial list of members and guests who called at Institute headquarters during the period Mar. 10, 1917, to Apr. 10, 1917. Frederick R. Ahbe, Athens, Pa. Frank M. Leland, San Francisco, Cal. J. L. W. Birkinbine, Philadelphia, Pa. Edwin Ludlow, Lansford, Pa. Samuel D. Bridge, Monterrey, Mex. E. P. Mathewson, Toronto, Canada. J. R. Buchanan, Pasadena, Cal. E. V. Matlack, Webster Grove, Mo. G. M. Colvocoresses, Humboldt, Ariz. E. C. Potter, Clearwater, Mont. F. G. Cottrell, Washington, D. C. R. B. Stanford, Bluefields, Nicaragua. H. N. Eavenson, Gary, W. Va. R. S. Ransom, Jr., Newark, N. J. H. T. Fisher, Englewood, N. J.. M. L. Requa, San Francisco, Cal. E. P. Fleming, Salt Lake City, Utah. John A. Rice, El Paso, Tex. F. L. Garrison, Philadelphia, Pa. W. E. Rice, Ringwood, N. J. W. M. Grant, So. Bethlehem, Pa. Lewis A. Riley, Philadelphia, Pa. J. F. Hanst, Negaunee, Mich. Hallet R. Robbins, Vancouver, B. C. H. D. Hibbard, Plainfield, N. J. Allen H. Rogers, Boston, Mass. B. B. Hood, Chrome, N. J. A. A. Stevenson, Philadelphia, Pa. Henry M. Howe, Bedford Hills, N. Y. Wm. Huff Wagner, Johnstown, Pa. Hennen Jennings, Washington, D. C. E. E. Watts, Denver, Colo. Oscar Lachmund, Greenwood, B. C. Samuel S. Wyer, Columbus, Ohio. H. W. Aldrich, after ten years of service with the Anaconda Copper Mining Co., at Anaconda, has resigned and accepted a position as general superintendent for the Ladysmith Smelting Works, at Ladysmith, B. C. Charles E. Bunker, formerly superintendent of the Keystone mine, has been appointed superintendent of the Bunker Hill mine near Amador City, Cal.

Jan 5, 1917

By H. W. Morse

THE CHAIRMAN (H. W. MORSE).-Gentlemen, for the first time in the history of the American Institute of Mining Engineers, we have a full session on the subject of leaching-especially on the leaching of copper ores.. This branch of metallurgy is rather in its infancy. We have had one big plant running for a year or more, and pretty successfully; and another one which will be started in February or March, the New Cornelia. We have another one at Garfield for the Utah company, which is just designed and construction begun; and from several other points come reports of interesting test work. The first paper on the program this evening is one of some of the test work on the New Cornelia ore by myself and Mr. H. A. Tobelmann. LAWRENCE ADDICKS, New York, N. Y. (written discussion).-The Ajo proposition has had, as I understand it, two great advantages: it has not been obliged to measure leaching against flotation or some other metallurgical process, and it deals with a copper content high enough

Jan 12, 1916

By Kenneth B. Ray, George R. Gardner

The application of wet cleaning processes for the beneficiation of bituminous coal has created in some localities a problem in the recovery and disposal of fine solids in the washery water. The maximum allowable concentration of these solids in the washery circuit that is consistent with satisfactory operation of the cleaning units remains a controversial point. It has, however, been generally recognized for a number of years that some degree of control should be exerted over the concentration of such material. Early methods of control involved intermittent or continuous discharge of a portion of the plant slurry into near-by streams or settling ponds, and this persisted even after the adoption of settling tanks or cones. The practice is not always economical, for two reasons: first, because of the waste of coal, and, second, because it is sometimes difficult and expensive to obtain an adequate supply of water. The latter condition often is aggravated by chemical treatment of the make-up water that is necessary to prevent excessive corrosion of plant equipment. The modern approach to this problem has been the adoption of continuous thickening devices. However, because such equipment occupies considerable plant space and is somewhat expensive to construct, the practice of loading these thickeners beyond their rated capacity is widespread, therefore often the performance of such units is not altogether satisfactory. In recent years, European washeries have increased the rate of settling of the fine coal from the slurry by the addition of specially prepared starch solutions. These reagents cause flocculation of the solid particles and thereby increase the rate of sedimentation. The first important work on the flocculation and clarification of coal slurry was done by Henry, who developed the Henry process and used it successfully in Belgian preparation plants. Soon after the initiation in Belgium, the process was introduced into England, where subsequent investigation developed similar processes, which were successfully used in

Jan 1, 1940

By George R. Gardner, Kenneth B. Ray

The application of wet cleaning processes for the beneficiation of bituminous coal has created in some localities a problem in the recovery and disposal of fine solids in the washery water. The maximum allowable concentration of these solids in the washery circuit that is consistent with satisfactory operation of the cleaning units remains a controversial point. It has, however, been generally recognized for a number of years that some degree of control should be exerted over the concentration of such material. Early methods of control involved intermittent or continuous discharge of a portion of the plant slurry into near-by streams or settling ponds, and this persisted even after the adoption of settling tanks or cones. The practice is not always economical, for two reasons: first, because of the waste of coal, and, second, because it is sometimes difficult and expensive to obtain an adequate supply of water. The latter condition often is aggravated by chemical treatment of the make-up water that is necessary to prevent excessive corrosion of plant equipment. The modern approach to this problem has been the adoption of continuous thickening devices. However, because such equipment occupies considerable plant space and is somewhat expensive to construct, the practice of loading these thickeners beyond their rated capacity is widespread, therefore often the performance of such units is not altogether satisfactory. In recent years, European washeries have increased the rate of settling of the fine coal from the slurry by the addition of specially prepared starch solutions. These reagents cause flocculation of the solid particles and thereby increase the rate of sedimentation. The first important work on the flocculation and clarification of coal slurry was done by Henry, who developed the Henry process and used it successfully in Belgian preparation plants. Soon after the initiation in Belgium, the process was introduced into England, where subsequent investigation developed similar processes, which were successfully used in

Jan 1, 1940