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Technology has no recognized rank in what is called polite literature; the subject-matter of engineering is not supposed to lend itself to artistic treatment; we are the hewers of wood and drawers of water to the high-priests of learning that live on the cold summit above our humbler dwellings. Therefore the hierophants smile at the notion of 'style'- “that curiously personal thing”--in technical writing. The "great art" of Pater, the "inevitable phrase" of Raleigh, the "note of distinction" that Arnold demanded are said to be beyond the scope, as they are supposed to be beside the need, of a writer on geology or engineering. This is a narrow view. Science, no less than belles lettres, calls for the best exercise of the human intelligence; the art of writing should be employed as skilfully and as earnestly in a description of the structure of the Sierra Nevada, or of the construction of a tunnel through the range, as in a rhapsody welcoming the rosy fingers of the dawn. The idea still lingers that fine writing does not befit technology, even though the masters of the Victorian period- Huxley, Tyndall, Ruskin-proved that science is worthy to be arrayed in the best robes that the looms of thought can weave. At the beginning of these lectures I quoted Barrie's remark touching the inability of the scientific man to express himself. That imputation has been passed to the technologist, whose utilitarian pursuits are supposed to make him too clumsy for the refinements of human speech. We may not have acquired the self-consciousness of those writers on Art whose "power of expression is so cultivated that their sensual caterwauling may be almost mistaken for the music of the spheres"; nor can we imitate the politicians, who have the ability to speak far beyond anything that they may have to say; but we too have a litera-

Jan 1, 1931

By H. H. Rachford, D. S. Howard

In the withdrawal of fluids from tilted aquifers it is of value to be able to predict pressure patterns during the course of the pressure decline. As an example of this, in the displacement of fluids from oil reservoirs being produced by water-drive, prediction of the reservoir pressure is an important factor in fixing production rate. The prediction of pressure patterns in the depletion of an inclined aquifer has conventionally been made by solving the well known flow equations for the pressure Patterns in a horizontal aquifer, and correcting these patterm for the pressure difference due to the hydrostatic head associated with the vertical distance between a point in the horizontal aquifer and the corresponding point in the tilted aquifer. Inasmuch as the equation describing flow in tilted strata is different from that for horizontal flow. there was question as to the validity of the simple corrective procedure current1y in use. To examine the magnitude of error made using this procedure, an inclined aquifer was chosen for which the error was expected to he large, and the equation for flow in this tilted stratum was solved numerically. The results of the conventional procedure of correcting the solution of the equation for horizontal flow was compared with the solution of the correct equation by studying the difference between predicted pressures by the two methods. Three forms of the hydrostatic head correction were studied. The results for all three forms of the head correction are similar. The error in the approximate solution is quite dependent on the position of the horizontal aquifer with respect to the inclined one. The error is greatest at the producing end ad increases with amount of fluid withdrawn. The magnitude of the errors is not large if a good choice is made for the position of the horizontal datum. The most satisfactory position for the datum in all cases is near or slightly about the mid-point of the inclined stratum. Use of the best approximate method studied with the best datum tested yielded predicted pressures in error no greater than 7 psi. INTRODUCTION The movement of water by expansion from an aquifer to displace fluids from a contiguous oil reservoir was first recognized over 20 years ago.9 Since that time much work has been done to relate this mechanism to reservoir behavior mathematically. The result of this effort on the part of many workers has led to an understanding of underground fluid movement which has enabled us to follow and predict the behavior of the water-drive reservoir. One reason that good progress has been made in the application of mathematics to the study of pressure patterns and water movements in aquifers has been that the differential equation which describes this process is of a relatively simple form. The equation for the isothermal, horizontal, viscous flow of water through homogeneous sandstone is identical with that for the diffusion of heat through homogeneous solids, and this equation and means of obtaining solutions for it with many types of boundary conditions have been studied extensively. That this work has been highly successful is clearly emphasized by the large number of solutions developed for problems of interest both by methods of formal mathemat-

Jan 1, 1957

By E. P. Dahlberg, R. E. Reed-Hill

On the assumption that stress or strain relaxation occurs as the result of a thermally activated process, equations are derived relating to tensile experiments that give the strain as a function of the time under the condition of constant stress, and the stress as a function of the time for constant strain. It is demonstrated that if the strain-rate equation i = previously proPosed by Kuhlmann., is used as a starting point, then the relaxation of strain at constant stress may be expressed by the equation c = (-RT/(Y) 1tz tanh (t + is the strain capable of being relaxed at any given instant. Similarly, it is shown that the relaxation of stress at constant strain may be given by a = (-RT/B) In tanh (t + t0)/27, where a is the instantaneois value of the relaxable stress. The fact that these relationships reduce to well-known empirical equations at both large and small values of the stress Or strain is also shozcn. The present theory is shown to agree well with experimental data obtained from tensile elastic aftereffect experiments on a zirconium specimen prestrained at 77 k as to make it strongly anelastic. It is also demonstrated that elastic aftereffect data obtained using torsional specimens ?,Lay agree reasonably well with the equation derived for the case of tension. RELAXATION experiments are often employed as a means of studying metallic deformation mechanisms.' The simplest and most commonly employed techniques involve stress relaxation at constant strain and strain relaxation at constant stress. In general, however, investigations of this nature have been seriously handicapped in the past by a lack of suitable equations giving the time dependence of the relaxing variable over an interval that extends from small strains up into the region where internal-friction experiments become strain-amplitude dependent. This paper presents a derivation of such a set of equations for the case where the time-dependent part of the strain is anelastic or recoverable and the specimens are loaded in simple tension. The relaxation of strain under the condition of constant stress will be considered first. Let us assume that strain relaxation occurs as the result of a reversible thermally activated process that occurs at a number of relaxation centers lying in an elastic matrix. Then, following Kuhlmann,2 we may express the rate of strain relaxation as follows: where C is the strain rate, AFx the free energy of activation of the process controlling strain relaxation, a, the effective or average resolved stress at the relaxation centers, u an activation volume, R the universal gas constant, T the absolute temperature, > a factor with dimensions of a volume that accounts for the strain contribution of a successful operation of a unit process, N the number of relaxation centers per unit volume, and v the Debye frequency. The first term on the right of Eq. [I] represents a strain rate in the direction favored by the stress, while the second term represents the rate in the opposite direction. It is implied in Eq. [I.] that both F and v are symmetrical with respect to the two basic directions of operation of a relaxation process. Eq. [I] may also be written where and S and Q are the activation entropy and activation energy, respectively, of the relaxation process. In the following, A will be considered a constant. This is compatible with a set of experimental conditions where the relaxation rate is controlled by a single basic reversible process in which it may be assumed that the temperature dependence of the product ?Nv is negligible in comparison with the temperature variation of the exponential term. It is also implied that v, 7, and N do not depend strongly on a, . In deriving a relationship for the strain as a function of the time from her equation, equivalent to Eq. [2], Kuhlmann2 chose to consider only the limiting cases where the time was either very small or very large. It will now be shown that it is possible to integrate Eq. [2] to obtain a single equation valid over a wide range of strains if the concept of relaxable strain is introduced. The use of this quantity, which is the difference between the instantaneous value of the strain and the value of the strain at complete relaxation, represents the primary point of departure of the present theory from that of earlier workers. Let us express the effective stress at the relaxation centers in terms of strain. For this purpose we may use the following equation derived by zener3 for the case of strain relaxation at slip bands: where M? and M are the relaxed and unrelaxed moduli respectively, go the applied constant tensile stress, and m an average orientation factor that takes account of the fact that a,, the effective stress at the relaxation center, may not be a tensile stress (i.e., a

Jan 1, 1967

By O. N. Carlson, S. A. Bradford

Discontinuous yielding in tensile tests was observed in V-O alloys in the temperature ranges of 150° to 175°C and also 350° to 400°C. The magnitude and intensity of the serrations were found to vary considerably with oxygen content. Maxima were observed in tensile and yield strengths and in the strain-hardening coefficient at the higher temperature only. The strain rate sensitivity was observed to be negative between 150° and 400°C. THIS investigation was undertaken to study the effect of oxygen on the tensile properties of iodide vanadium in the temperature range of 25o to 450°C. Brown1 observed an increase in strength between room temperature and 400°C in vanadium metal, and found that oxygen and nitrogen had a rather pronounced effect on the strength and ductility. A maximum in the tensile strength was observed by Rostoker et al.2 near 300oC and by Pugh3 around 450°C for calcium-reduced vanadium. Pugh also found a maximum in the yield strength and in the strain-hardening exponent, and minima in the elongation and strain rate sensitivity at the same temperature. Eustice and Carlson4 reported the appearance of serrations in the stress-strain curves between 140° and 180°C in iodide vanadium containing 600 ppm O. These anomalies in the mechanical properties indicate that strain aging occurs in vanadium, but the impurity or impurities responsible for the above-mentioned effects have not been identified. The phenomenon of strain aging is usually characterized by the return of the yield point after interruption of a strength test. In the temperature range where strain aging occurs, the yield and tensile strengths attain maximum values, elongation and strain rate sensitivity exhibit minima, and discontinuous yielding is generally observed in the stress-strain curve. Cottrell5, 6 has postulated that strain aging is due to the migration of solute atoms to dislocation sites to produce locking after the dislocations have broken free from their impurity atmospheres during the initial yielding. At the strain-aging temperature the process is a dynamic one in which the solute impurity atoms diffuse to the vicinity of the moving disloca- tion producing "locking" which gives rise to maxima in the tensile strength and serrations in the elongation curves. Cottrel17 has noted that discontinuous yielding in iron occurs when the diffusion coefficient of nitrogen, D, and the strain rate, i, are related by D = 10-9 €. EXPERTMENTAL PROCEDURE The vanadium metal employed in this study was prepared by the iodide refining process as described by Carlson and owen.8 A representative analysis of the vanadium used in this investigation was: 150 ppm O, <5 ppm N, <1 ppm H, 150 ppm C, 150 ppm Fe, 70 ppm Cr, <50 ppm Si, 30ppm Cu, 20 ppm Ni, <20 ppm Ca, <20 ppm Mg and <20 ppm Ti. Alloys containing from 200 to 1800 ppm O, all of which lie in the solid solution range of the V-O system, were prepared by arc melting vanadium together with portions of a high-oxygen master alloy. The master alloy was prepared by tamping pure V2O5 into holes drilled in a vanadium ingot and arc melting this five or six times in an inert gas atmosphere, inverting the button between each melting step. The oxygen content of the master alloy was then determined by vacuum fusion analysis. Vanadium containing less than 150 ppm O was prepared in the following manner. A bar of iodide vanadium was deoxidized by sealing it in a tantalum crucible with a few grams of high-purity calcium. This was held at 1100°C for 4 days to allow time for the oxygen to diffuse to the surface and to react with the calcium vapors. The calcium oxide product was later dissolved from the surface of the bar with dilute acetic acid. In this way vanadium containing from 20 to 50 ppm O was prepared. Sample Preparation. The are-melted ingots were cold swaged into 3/16-in. diam rods and these were machined into cylindrical tensile specimens with a reduced section of 1.00-in. length and 0.120-in. diam. The test specimens were annealed for 4 hr at 900°C in a dynamic vacuum of mm of Hg to remove hydrogen from the metal. This recrystal-lization treatment produced a uniformly fine-grained structure with a mean grain size of approximately 0.06-mm diam. The oxygen contents reported in this paper were determined by a vacuum fusion analysis of the tensile specimens after testing. Analyses for other interstitial or metallic impurities showed no significant changes from that of the original material. Tension Tests. Tension tests were performed on a screw-driven tensile machine at a constant cross-head speed of 0.01 in. per min. Tests at elevated temperatures were carried out by heating the

Jan 1, 1962

By H. E. Cline

Calculations of the formation and growth of faults caused by a variation in lumellar widths were made for a two-dimensioml three-plate problem. The angle between the a-ß boundary and the growth direction was allowed to vary and the time evolution was studied using a quasisteady state approach. At spacings smaller than a critical spacing given by X V = AO variations in the larrlellar widths grow in time to produce faults that coarsen the structure, while at spac-ings larger than this critical spacing, variations in the lamellar widths decay in time. If small plates are introduced into the structure they may grow only at large spacings to refine the structure. The time evolution and shape of faults were calculated for the three plate-problem and then the three dimensional problem and rod-like eutectic were qualitatively discussed. UNDERSTANDING of the mechanism by which the spacing of directionally solidified eutectics is determined may allow one to control their structure better. Steady state solutions for the growth of lamellar structures have been found for a range of lamellar spacings A and growth velocities V. To obtain a unique solution for the isothermal growth of pearlite, Zener1 assumed that growth occurs at a maximum velocity, while Tiller2 assumed that a eutectic alloy, grown under an imposed velocity, will choose a spacing corresponding to minimum undercooling. These assumptions are equivalent and have been referred to as "extremum growth". The extremum condition predicts the observed relation between velocity and spacing as given by V = constant [I] but does not provide a mechanism for changing the lamellar spacing. Jackson and Hunt3 calculated the interface shape by using solutions to the diffusion equation for a planar interface and a relation of the interface composition to the local curvature. If the spacing is much larger than the extremum spacing, the interface breaks down catastrophically to form forked plates. However, the catastrophic breakdown cannot account for the small adjustments in spacing that must occur in practice..3 Direct observations during the growth of organic eutectics4 and the Pb-Sn eutectic5 show that spacing changes occur by the formation of faults. A fault in a plate-like eutectic is the edge of a plate. Once the faults form, they may move to make small adjustments in the spacing.6,3 The motion of faults intersecting the growing interface was shown by an approximate analysis to give Eq. [I].6 A perfectly regular lamellar structure should be able to persist over a range of lamellar spacings. However, during growth small perturbations in the structure may occur. If the amplitude of the perturbation increases in time the structure is unstable, while if all possible perturbations decrease in time the structure is stable. In a previous paper7 variations in the shape of the solid-liquid interface were considered, while this paper considers only variations in lamellar widths while maintaining a macroscopically planar solid-liquid interface. Previously, theories of lamellar growth1"3 have artificially contrained the growth to give a regular periodic structure. To allow for a variation in spacing, the three phase intersections and groove angles were allowed to change with time as determined by assuming local equilibrium. THREE-PLATE PROBLEM Since the spacing changes in eutectics by local formation of faults,4&apos;5 it is suggested that local variations in spacing are responsible. The interaction between neighboring plates will be greatest because they have the smallest diffusion distance. For simplicity, as a nearest neighbor approximation, a three-plate problem will be considered, as illustrated in Fig. 1. The structure consists of a periodic array in which all the plates are allowed to vary in width. As in steady state growth it is assumed that the average composition in the solid remains constant. A variation in plate widths, that maintains the composition in the solid, was introduced by making the first a-phase plate thinner by an amount A, keeping the width of the second B-phase plate constant, and increasing the width of the third a-phase plate. If the structure were not perturbed, as in the regular two-plate problem previously described,&apos; then the groove angles at the three-phase junctions are the equilibrium angles, 0, and ? B, and the solid-solid boundary is normal to the interface. In the three-plate problem with a variation in plate widths the phase boundaries are assumed to be related to the three-phase junction by equilibrium angles, but the a/B boundaries may be rotated by an angle 0 from the growth direction. The angle H be-tween the tangent to the a/B boundary and the growth direction may vary during growth and determine the —> — — —.A_ Q-0 / 0 x, X2 Fig. 1—Schematic of the three-plate problem showing a variation in the spacing and the effect on the angles at the three phase intersections.

Jan 1, 1970

By C. H. Bowen

NDUSTRY needs a generally applicable means of defining average grain size and grain size distribution. Students of sediments hade explored this field, employing methods that might also prove useful in engineering problems. Before attempting to solve specific problems it is well to review the derivation of commonly used grade scales and the reasons for their selection. This aspect of the problem seems largely to have been lost, and a review of basic factors may suggest causes for failures in using size analysis data. Three facts are implicit in selection of a grade scale: 1) Most particulate mixtures are continuous distributions of sizes, and any grade scale that may be employed is an arbitrary means of visualizing that distribution. 2) For purely descriptive purposes, any grade scale, regardless of the rationality of the class intervals, will be satisfactory if it is accepted by a sufficient number of workers. 3) For analytical purposes, class intervals must be small enough to define the continuous distribution accurately. Further, where statistical studies are involved, a fixed relationship should exist between classes or grades. An argument in favor of geometrically related size grades lies in the fact that most particulate mixtures contain such a wide range of sizes that use of an arithmetic diameter scale is practically impossible. Udden, who recognized this fact in 1898,&apos; proposed one of the first grade scales based on a regular geometrical interval. Udden used 1 mm as his basic diameter and a ratio of 2 (or 1/2) between classes. In 1922 Wentworth2 re-examined Udden&apos;s grade scale, retaining the same class interval and basic diameter, but extending the scale in both directions and renaming the classes. In 1930 (Ref. 3, p. 82) the American Society of Testing Materials proposed what is now known as the U.S. Standard fine sieve series, also based on the 1 mm diam, with a v2 ratio between sieves. This, then, is a one fourth Udden-Wentworth series in the sizes below the 4 mesh sieve. The U.S. Standard coarse sieve departs from the 1 mm base and uses inches; hence it is not a direct continuation of the fine series. The U.S. Standard series would thus seem to possess all the attributes of a good grade scale, which it is. It has a large number of classes (sieves). in fact too many for practical use in its entirety. This v2 subdivision of the Wentworth grades has led to the common use of two v2 sieve series, the half-Wentworth and the engineers&apos; series. Geologists and sedimentologists favor the half Wentworth, or 18, 25, 35, 45 sieves, etc., whereas the engineers, preferring round numbers, utilize the other half of the U.S. Standard grade scale in the 16, 20, 30, 40 sieves, etc. The fixed geometrical ratio between classes is an advantage in statistical analysis, but the unequal classes cause some complications in calculations. This is especially true when moment measures are used. It was to simplify these calculations that Krumbein in 1934 devised the phi scale. Phi is defined as being equal to —log2 of the diameter in millimeters. Selection of logarithms to the base 2 relate the phi scale directly to the Wentworth grade scale in such a manner that the whole or fractional diameter values 2, 1, 1/2, 1/4 mm, etc., become rational whole numbers, —1, 0,1, 2, etc. Since this is an arithmetic rather than geometric series, calculations are facilitated. When the logarithm is multiplied by —1 the phi values below 1 mm become positive, those coarser than 1 mm negative. Because of its relationship to the Wentworth grade scale (and in turn to the U.S. Standard fine sieve series) it is not necessary to use the transformation equation to calculate the phi value for each individual sieve; this can be done graphically as shown in Fig. 1. It should be noted that this graph may be extended in either direction to include the range of sizes most commonly used by the individual worker. Application to Statistical Analysis Any attempt at systematically relating size analysis data to properties involves a statistical study whether it is recognized as such or not. Since this is true it would seem more logical to use measures and devices related to the general body of statistical theory. Several methods are available for studying particulate mixtures. One of the most commonly employed, and also the most often misused, is the histogram or block diagram. If its limitations are recognized and provided for, the histogram is a very useful tool. According to conventional practice, the bars of equal width are plotted and the values noted in terms of diameters, when in point of fact, log diameter is implied by such notation. Further, the histogram is sensitive to choice of grade scale and size of class interval, either of which may color the result. Grade scales whose classes are not related by fixed intervals are particularly difficult. Another basic weakness of the histogram is that it pictures a continuous distribution as a series of discrete grades.

Jan 1, 1957

By T. A. Rickard

Technology has no recognized rank in what is called polite literature; the subject-matter of engineering is not supposed to lend itself to artistic treatment; we are the hewers of wood and drawers of water to the high-priests of learning that live on the cold summit above our humbler dwellings. Therefore the hierophants smile at the notion of &apos;style1-" that curiously personal thingy-in technical writing. The "great art" of Pater, the "inevitable phrase" of Raleigh, the "note of distinction" that Arnold demanded are said to be beyond the scope, as they are supposed to be beside the need, of a writer on geology or engineering. This is a narrow view. Science, no less than belles lettres, calls for the best exercise of the human intelligence; the art of writing should be employed as skilfully and as earnestly in a description of the structure of the Sierra Nevada, or of the construction of a tunnel through the range, as in a rhapsody welcoming the rosy fingers of the dawn. The idea still lingers that fine writing does not befit technology, even though the masters of the Victorian period-Huxley, Tyndall, Ruskin-proved that science is worthy to be arrayed in the best robes that the looms of thought can weave. At the beginning of these lectures I quoted Barrie&apos;s remark touching the inability of the scientific man to express himself. That imputation has been passed to the technologist, whose utilitarian pursuits are supposed to make him too clumsy for the refinements of human speech. We may not have acquired the self-consciousness of those writers on Art whose "power of expression is so cultivated that their sensual caterwauling may be almost mistaken for the music of the spheres"; nor can we imitate the politicians, who have the ability to speak far beyond anything that they may have to say; but we too have a litera-

Jan 1, 1931

By Lawrence Addicks

ONE of the properties of copper, which has done much to give it its present prominent place among the useful metals, is its electrical conductivity, a property which has now become the chief criterion of &apos;the value of the commerical product. In pursuance of that distinctively American principle that, 1&apos; the best is none too good," metal of the highest conductivity is usually called for even where such extreme purity is of no advantage, for instance, in the making of brass and other alloys. The average brass-founder feels nervous unless his copper is so very pure that it shows a conductivity of 99 or 100 per cent., while the character of the zinc used is usually overlooked in his anxiety. Electrolytic refining has made it possible to produce copper of a&apos; very high degree of purity, the metallic impurities averaging but a few thousandths of 1 per cent.; oxygen, usually present in the form of cuprous oxide, bringing the total up to about a tenth of 1 per cent. The published data bearing upon the relationship between chemical purity and electrical conductivity is, however, very scant,&apos; nearly all the work that has been done having dealt with alloys carrying considerable quantities of the foreign elements. In this paper I have brought together the results of experiments extending over a period of several years that have been carried out with the idea of determining the amount of various elements which would lower the conductivity 3 or 4 per cent.-a series of impure coppers rather than alloys. There are many precautions necessary to keep the conditions

Mar 1, 1905

By Michael A. Gustafson, Fernando B. Sotelino

INTRODUCTION The degree of success of any new project will ultimately depend on two factors: (i) the underlying economic strength of the project; and (ii) how successfully the parties involved can coordinate their interests to establish a financing structure which indeed capitalizes on the project&apos;s inherent economic attractiveness. A project&apos;s underlying economic attractiveness is determined by its inherent comparative advantage in accessing the factors of production, combining these factors of production to create a product and marketing this product. Initially, the decision regarding whether to go ahead with the project - the go/no go decision - has to be based on its total ability to generate cash flow returns to project participants to compensate them for resources committed and risks undertaken. The extent to which project sponsors will actually benefit from the project&apos;s inherent economic attractiveness is fundamentally dependent on their ability to establish the long-term financing arrangement which best meets the objectives and constraints of each project participant and sources the most advantageous funding. The decision regarding the financing of the project, the "how-to-go" decision, is then an attempt to find the capital structure, consistent with market terms and conditions and sound financial management policies which will best: (i) match planned outflows with cash inflows; and (ii) maximize the return for project sponsors. This article makes use of a case study to illustrate the analytical process involved in dealing with the go/no go and the how-to-go decisions on a project. Though most commonly applied to project finance situations, the guideline described herein is equally applicable to other financing situations, such as leveraged buyouts and debt restructurings, where timely repayment of debt depends largely on the future cash flows to be generated by the entity being financed. Our case study is of a hypothetical expansion of an existing copper mining operation in Latin America. The company, Latin American Copper (LAC) currently has 147 million metric tons of proven sulphide ore reserves. The existing mine complex consists of an open pit mining operation and a conventional flotation plant with a processing capacity of 20,000 metric tons of ore per day. LAC sells copper concentrates primarily to Japanese custom smelters. The mine has been in operation for 5 years, fine copper production last year was 108,240 metric tons, and LAC currently has assets of $175 million and net worth of $135 million. Due to a recent increase in proven reserves, LAC is considering doubling the treatment capacity of its flotation plant to 40,000 tons per day, and expanding its mining capacity to meet the additional concentrator capacity (the "Project"). Project capital expenditures and incremental working capital have been estimated at approximately $210 million. The construction period is expected to cover one year, including a three-month start-up phase. The Project is to be funded by a combination of equity, senior debt, including both supplier credits and/or commercial bank term loans, and subordinated debt. LAC&apos;s shareholders are willing to commit a maximum of $50 million to the Project. A government development agency, which is also a minority shareholder, might be willing to lend approximately $40 million to LAC in the form of subordinated notes, depending on the ability of the Project to generate foreign exchange reserves. Commercial banks cannot be expected to offer loans with maturities longer than ten years. The Project is expected to increase the value of the firm because: (i) It will solidify the Company&apos;s position as a low-cost copper producer by taking advantage of economies of scale. As a result of the expansion, cash production costs are expected to decrease 7.0[c]/lb. and all-in costs 11.0[c]/lb; (ii) The potential earnings stream from the sulphide ore reserves will be realized

Jan 1, 1985

By H. Foster Bain

Steel for any large structure must be imported, the Hanyang works being entirely unable to supply local demand. The United States Steel Products Co. has warehouses and small stocks at Shanghai and at normal times there are heavy importations from Europe. It is difficult to obtain any accurate index of prices, but comparison of customs valuations with Pittsburgh quotations shows angles, bars and plates to have averaged $10 gold per ton higher in China in 1914, while on galvanized and tinned plates the excess was- $38 per ton. The margin since has been greater. Previous to the war little machinery was manufactured in China. There were shipyards at Shanghai and at Hong Kong which built a small number of engines, and small foundry and repair works are found at a number of ports. Their capacity was limited and the difficulties and delays incident to transport in China so numerous that in practice every important mine has a small foundry, boiler works, and machine shop. This must be taken into account in plans for work in the country. While skilled workmen can be found it is to be noted that most of them have been trained

Jan 1, 1921

By E. J. Schmitz

This novel safety-lamp, which was first introduced in some of the German coal-mines in 1882, at once attracted general attention in the coal-districts of Europe. Objections which arose during the early stages of its use at the mines have gradually died away with the increase of experience in handling the lamp 011 the part of the miners, and the continual efforts to perfect it on the part of its inventors. Wolf&apos;s lamp has rapidly surpassed all its rivals, and has already a greater distribution on the Continent than any one of its older sisters. In the course of two and a half years, the manufacturers have sold 25,000 of the lamps, besides remodelling several thousand rapeseed-oil lamps. This great success, which of itself speaks loudly enough as to the superiority of the Wolf benzine-lamp, is corroborated by both official and private reports, which all agree in pronouncing this lamp the best yet brought forward. It was described in a paper by Mr. Eugene B. Wilson, read at the Chicago meeting of the Institute, in May, 1881,* in which its salient merits were briefly but clearly indicated. Every previous improvement of the original Davy lamp has been directed to one or more of the following main points: 1. Light of greater and more uniform intensity. 2. Freedom from smoke or soot, which clogs the gauze and other parts of the lamp. 3. A greater safety and sensitiveness in the presence of firedamp. 4. An illuminating material which, satisfying the foregoing conditions, should be also cheap. 5. A lock which could not be opened in the mine by the miner. 6. An arrangement for lighting without opening the lamp. 7. An arrangement for changing the size of the flame in the closed lamp, to supersede the picker, the danger from which is explained in Mr. Wilson&apos;s paper, already cited. It may safely be said that wolf&apos;s lamp was the first to secure all these objects. The adoption of benzine instead of rapeseed-oil (previonsly the best illuminant) has completely satisfied conditions 1, 2, 3, and 4. Benzine gives a much clearer, stronger, and more uni-

Jan 1, 1886

Discussion of the paper Of ROBERT H. BEDFORD and WILLIAM HAGUE, presented at the Salt Lake meeting, August, 1914, and printed in Bulletin No. 92, August, 1914, pp. 1807 to 1816. W. L. SAUNDERS, New York, N. Y. (communication to the Secretary *) . -Messrs. Bedford and Hague have given us a very interesting and practical paper. No better excuse for such a paper could be desired than the statement made that the expense of drilling. in this mine is one-third of the cost of delivering the ore at the mill. This statement. should be written in red letters, because it applies to a great many mines besides the one referred to and because it is generally true that in a mining plant, as also in papers read before the Institute, more attention by fat is given to the metallurgical side of mining than to the excavation of the ore, and no study of the excavation work is properly made that does not involve a careful inquiry into the merits of the rock drill used. Next in importance to the selection of a good rock drill, in a case where the actual drilling cost is one-third the cost of delivering the ore, is that. the drill should be maintained in order and kept up to its highest efficiency. The best rock chill may run down in efficiency through accidents, wear, or other conditions which are sometimes beyond supervision or control. The machine is usually in the hands of men who know how to get workout of it, not men who know how it works. The best drill runners are not machinists,. but miners. They could not tell you how the valve operates or the principle of the rotation, but they know how to get the work done. A testing machine, particularly the type described in this paper, may he of the greatest value in maintaining a uniform state of efficiency.

Jan 11, 1914

By A. B. Stevens

IN the calculation of oil and gas reserves by volumetric methods, it is necessary to know the volume of the reservoir available for the storage of the oil or gas. To obtain this information, a number of methods for determining both total and effective porosity of reservoir rocks are used. For the determination of the total porosity, or the porosity that considers all of the pore spaces, connected and isolated, the Russell7,8,9 and the Melcher-Nutting1-6 methods are the best known and most- widely used in the petroleum industry. These methods have disadvantages in that they give the total porosity of the samples and in that the samples are reduced to grain size in the determination. In many sands there may be little or no difference between total and effective porosity but in other sands there may be considerable difference between the two. For the estimation of oil-and gas reserves the effective porosity of the reservoir rock always should be used. Of the methods that have been developed for the determination of the effective porosity of reservoir rocks, or the porosity that considers only those pore spaces that are connected, the best known are the so-called Boyle&apos;s law6,10-13, and the Washburn-Buntings.5,6,11 methods. The Wash-burn-Bunting method is probably the most widely used because it gives effective porosity, it is rapid, and the apparatus is inexpensive. This method employs a special porosimeter in which the core sample is placed in direct contact with mercury. This method has disadvantages in that, as a result of the high vacuum created in the pore spaces, mercury is drawn into the openings, making it impossible to use the sample for a check determination and also ruining the sample for any further test, such as permeability. The purpose of this paper is to describe an appa-ratus employing the same principle as the Washburn-Bunting method but so designed that the core sample does not come in contact with the mercury in the porosimeter.

Jan 1, 1939

Prof. HEnRy Louis, Newcastle-upon-Tyne, Eng. (communication to the Secretary*):—I welcome Mr. Hammond&apos;s paper as an attempt to give definiteness to the best modern professional practice. Such a codification of our professiollal ethics is urgently needed, seeing how widely the views of nlining engineers direr on some of the points raised; for example, I have no hesitation in performing a class of work, as to which Mr. Hammond seems to entertain some doubts, and, on the other hand, I strongly condemn a practice which he appears to recommend. I have not the least hesitation in making reports for vendors of mining-properties, and am constantly doing so; the best justification for this practice may be found in the fact that such reports have been repeatedly accepted by buyers as giving a correct representation of the facts of the case, which is all that should be demanded from any report. On the other hand, Mr. Hammond advocates that mining engineers should take payment for their reports in shares of a company to be floated upon the basis of such reports. I hold that this is ethically wrong, as even themost honest of men is liable to be unconsciously biased under these conditions. Indeed, I go much further, and maintain that a mining engineer who reports or advises upon mining-properties should never hold any mining-shares at all, or be himself interested in any mine, and this has been my consistent practice for many years. A man who hold shares in a mine, and is called upon to report upon a neighboring property or a similar mine, can never be wholly unbiased; and even if he could be, he would always lay himself open to the suspicion that he was giving a favorable report 80 as to enhance the value of the property in which he himself is interested, or an unfavorable report so as to stifle competition. It is quite as bad for the manager of a mine or the consulting manager to be interested, because he will have access

Jan 1, 1910

By Ernest Burchard

FLUORSPAR is found in most of the states from the Rocky Mountains westward, and commercial production of the mineral has been reported from Arizona, Colorado, Nevada, New Mexico, Utah and Washington. The map in Fig. 1 indicates the general distribution of many of these deposits but it is by no means complete. In the summer of 1926 the writer examined certain deposits of fluor-spar in Arizona, California, Colorado, New Mexico and Washington; in November, 1927, revisited the Jamestown, Colo., district, and in earlier years examined deposits in Colorado and New Mexico. Based on notes of his own and. on descriptions and other data by H. A. Aurand, H. W. Davis, R. B. Ladoo, V. C. Heikes, W. D. Johnston, Jr., and by producers of fluorspar, he prepared the following brief descriptions of deposits and estimates of reserves of fluorspar, originally for the use of the subcommittee on fluorspar of the Joint Committee on Foreign and Domestic Mining Policy and on Industrial Preparedness respectively of the Mining and Metallurgical Society of America and the American Institute of Mining and Metallurgical Engineers. Descriptions of many fluorspar deposits in various western states and districts have been published. It is not feasible to summarize this literature here, but the appended bibliography will indicate to the interested reader what papers are available.

Jan 1, 1933

By Carl Gatlin, S. Srini-Vasan

It is shown thar k k ratios cornputed on the as.sutnption that the average sandstone reservoir has a pore-size distribution characrerized by a linear 1/P saturatioN plo are in good agreewient with correspotlding k,,/k,, ratios obfairzed by Wahl, Mul-/ins and Elfrink by correlatiotz of field measurements. Methods of calculating relative permeability data have recently been reviewed and extended.&apos; It was shown that for sandstone reservoirs where &apos; is approximately a linear function of effective saturation (as suggested first by Corey&apos;) it is possible to express relative permeabilities in very simple terms. For systems wetted by connate water and producing oil and gas (gas saturation growing at the expense of oil) the expression for the The accuracy of Eq. I has been frequently confirmed in our laboratories; because of its simplicity we make routine use of it in the analytical solution of proble~ns in reservoir engineering. Nevertheless, comparisons of the k,,,/k,, ratios yielded by Eq. 1 with appropriate reservoir data have been few. The publica- tion by Wahl, Mullins and ElfrinkV of an empirical equation for k,,/k,, ratios is thus of interest since this equation is specificalljl stated to be Vased on the correlation of field measurements made on sandstone reservoirs. Not surprisingly these authors found that it was necessary to

By Adrian C. Dorenfeld

Laboratory data form the basis for the design of flotation circuits. These data, obtained from testing samples of the ore, should show the optimum con- ditions for concentrating the ore and the effects of change in process vari- ables. Among the more important variables commonly met in flotation practice are: Liberation Size-This is the particle size at which substantially all of the valuable minerals are detached from the gangue minerals. Reagent Additions- Experimental data will show the reagents used and their quantity, quality, and point of addition. Pulp Density-This is an important variable in the design of the flotation circuit because it is one of the factors determining the size and number of flotation cells. Flotation Time-The time necessary to make the separation into concentrate and tailing depends on such factors as particle size and reagents used and must be known for determination of the size and number of flotation cells in the plant. Temperature of Pulp-Temperature affects flotation reactions. Water at approximately room temperature is satisfactory for most flotation separations, but some minerals such as fluorspar are best floated in hot water. Type of Circuit-Many types of circuits can be designed, as discussed in detail later. The laboratory tests should provide data for design of the plant circuit best suited to the ore. Water-Knowledge of the quality of the future plant&apos;s raw water is important because water quality may drastically affect flotation results. If possible, flotation tests should be made using samples of the water to be used in the plant. Flotation results may vary with seasonal temperatures and with circulation of reclaimed water. Experimentation can show whether it will be necessary to provide for heating, cooling, treating, or reclaiming the water. Uniformity of Ore-The extent of variation of the ore in hardness, grind- ability, mineral content, and floatability should be investigated so that the designer can ascertain methods to overcome problems caused by ore variations. Settling and Filtration Data-To design the plant flotation circuits, settling and filtration rates and ultimate percentage solids of the various products must be determined. Corrosion and Erosion-Corrosion and erosion tests should be made on the flotation pulps, particularly if the pulps are acid or at an elevated temperature, so that suitable materials of construction can then be chosen.

Jan 1, 1962

By Homer F. Staley, C. P. Karr

The casting alloy 88 copper, 10 tin, 2 zinc, commonly known in England as Admiralty metal and in this country as Government bronze, gun metal, or Naval Department composition G, has, at its best, many valuable properties. However, its physical properties are known to vary widely with slight changes in method of manufacture of the castings, such as slight variations in composition, variation in pouring temperature, kind of mold used, method of pouring and gating of molds, size and shape of castings, amount and kind of heat treatment, and so forth.&apos; The microstructure of castings made from this alloy is influenced by slight variations of composition, rate of cooling, and kind and length of heat treatment. This is best understood by reference to the equilibrium diagram. The part of the diagram in which we are interested and the effect of the thermal equilibrium relations on the physical properties of the alloy 88 copper, 10 tin, 2 zinc, have been discussed by Hoyt, Campbell, Primrose, and Rawdon.2 In Fig. 1 is given the equilibrium diagram of the copper-tin alloys. Briefly stated, the relations of composition and temperature changes are as follows. Compositions between A and a consist of but one constit ent—the a bronze, which is a solid solution of copper and tin, rich in copper. On cooling from the molten state these compositions gradually crystallize, at temperatures above 790°, into a mass of interwoven treelike crystals or dendrites. The cores of the dendrites are rich in copper and the percentage of tin gradually increases as the surfaces are approached. AS cooling progresses, after a11 the metal has crystallized, no further changes occur in the crystals other than diffusion within the crystals, which tends to erase the dendritic pattern and to render the structure more homogeneous. * Metallurgical Ceramist, U. S. Bureau of Standards, Associate Physicist, U. 8. Bureau of Standards. A. D. Flinn: Iron. Age (1915) 96, 1292-3. C. P. Karr: U. S. Bureau of Standards Tech. Paper 59, Pt. 1. S. L. Hoyt: Enging. (1913) 96, 667-7, 704-5. William Campbell: Trans. Am. Inst. Met. (1912) 6, 158-172. H. S. Primrose: Metal Ind. (1916) 14, 202-4. H. S. Rawdon: U. S. Bureau of Standards Tech. Paper 59, Pt. 11.

Jan 1, 1921

By R. M. Raymond

RECENTLY one of the Welsh coal companies, which has an excellent plant of up-to-date ma-chinery both on the surface and underground, operated under modern methods, sent one of its engi-neers to the United States to study actual operations in the mines. He visited several of the most important and best conducted collieries, went back, and reported that the greatest difference between operations in England and in the United States was. the closer con-tact between management and workmen. By manage-ment he meant management all the way through; close cooperation between office management, superintend-ents, foremen, shift-bosses, etc., and the workmen. A visit to some of the coal mines in that country by the writer made this fact rather impressive. The feel-ing on this side of the water that the methods in use in the coal mines in England are not up-to-date was found in many cases to be quite erroneous. Many mines, particularly those with very thin beds, in which profitable operations are doubtful under the best con-ditions, have necessarily had to adhere to old methods instead of making mechanical improvements. The Powell-Duffryn mines, in the center of the South Wales district, are certainly operating successfully, and have planned their business excellently. Sufficient areas of contiguous land have been leased for extended opera-tions. Mine plants are laid out in the valley, for work-ings on both sides, on a reasonable tonnage of 1500 to 3000 tons to each operation. The beds are from 30 to 48 in. thickness, and a 3-ft. seam is considered an ex-cellent thickness of coal; in fact, the miners prefer to work on the thinner beds rather than the thick ones, where they consider it more difficult to control the backs. This company is making use of its fine coal for produc-ing electric power, which is distributed to its own operations, and for use in the communities adjoining. For this purpose methods of cleaning the fine coal are being put into use. Compressed air is generated at the central power plant and is transmitted over long dis-tances to various mines in each valley. A byproduct coke plant uses more of the fine coal and gives further returns from non-commercial coal. The long-wall system applied in sections of limited size is popular in working the small seams, and me-chanical cutting is used, also handling either by shaking chutes or belt conveyors, or a combination of both. In some mines mechanical cutting is not necessary. The backs are so handled that in the softer or somewhat crushed seams hand cutting can be carried on effec-tively.

Jan 10, 1927

By Y. C. Liu, R. H. Richman

Deformation and recrystallization textures of the a solid solutions of Cu-P, Cu-As, and Cu-Sb alloys are examined as a function of composition. It is found that the deformation texture of copper is unckanged up to a composition of 0.43, 0.41, and 0.24 at. pct of phosphorus, arsenic, and antimony, respectzvely, and then the transition to the 70 : 30 brass type of deformation texture proceeds linearly as the logarithm of the solute content. Recrystallization textures consist of strong, new components that do not all bear the usual<111> rotational relation to the deformation components. The dependence of the deformation texture transitions and the recrystallization orientations upon composition and solute-element type is discussed. A systematic evolution of individual recrystallization components in the annealing texture of copper was portrayed as a function of germanium or tin content in a previous study.&apos; Similar patterns of tex-tural change have been observed with copper-zinc alloys,2 and in less detailed studies of other systems.3,4 In fact, most of the literature dealing with preferred orientations in copper alloys indicates that the influence of solute elements upon textures in copper is of one general type. As the alloy content of copper is increased, the deformation texture changes from the copper type to the 70:30 brass type, and the annealing texture undergoes a comparable change from the (001) [ loo] orientation of unalloyed copper to the {113} <211> type of 70:30 brass, with the notable exception of copper alloyed with Periodic Subgroup V-B elements.4-8 In almost every case it is possible to describe the reorientations after annealing as 30 to 40 deg rotations about <1ll> poles of the deformation components. Since there is apparently not much difference in the final textures of the copper binary systems already investigated, only a limited variety of preferred orientations has served as the basis for current theories of the origin of annealing textures. In order to test the validity of the proposed theories, and the possibility that the <111> rotations are not unique, it would be most desirable to study the reorientation relationships of additional, and heretofore unanalyzed, recrystallization components if such components exist. Examination of the literature reveals a good deal of uncertainty concerning preferred orientations in copper alloyed with elements in Subgroup V-B of the Periodic Table. Phosphorus is known to inhibit the cube texture in copper when present in amounts as low as 0.01 wt pct,8 but the recrystallized matrix that occurs instead of the cube orientation was reported as either random or weakly textured, with orientations not observed in Cu-Zn, Cu-Ge, or Cu-Sn alloys.4-9 A Cu-0.75 at. pct As alloy apparently contained, along with the (001)[100] and (113) <211> type of recrystallization components, {110} <112> and (110) <001> components, whereas an almost random distribution of orientations was found in alloys of higher arsenic content.4 A {110} <001> component also appeared in rolledand annealed Cu-Sb alloys, but otherwise the recrystallization textures of Cu-Sb alloys seem to con-

Jan 1, 1962