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By N. M. Macmillan, R. S. Kalyoncu, A. R. C. Westwood

The environment-sensitive hardness and laboratory-scale rotary drilling behavior of granite, quartz, and feldspar have been studied. By controlling the chemistry of the drilling environment, it is possible to triple the rate of drilling granite. Pre-existing flaws or other microstructural features play a minor role.

Jan 1, 1975

By Hans M. Ewoldsen

The generation and evaluation of solutions to body force problems is of extreme interest to the geotechnical profession, as all natural stress states must necessarily include some contribution from the weight of the material. In this chapter the elastic solution for the stress field around a circular, horizontal tunnel at an arbitrary depth beneath the surface of a half-space is reexamined. The influences of body force, initial stress, and free surface proximity are examined and related to in-situ cases. The solution as presented deals only with an isotropically elastic medium; this medium is further considered only in a half-space configuration. It is readily apparent that these restrictions impose severe limitations if analogies are attempted with in-situ cases where geologic discontinuities, inhomogeneities, and irregular boundaries exist. The question might be raised as to the propriety of geotechnically oriented researchers even considering such idealized conditions. There is, however, much to be gained from study of such solutions. The lack of geologic discontinuities and inhomogeneities allows the investigator to separate and leisurely examine such parameters as are included in the solution, without worry of interrelationships of a host of other parameters. Further, elastic solutions have had extensive usage prior to the development of such techniques as the finite-element solution. It is interesting to compare body force solutions with the external field solutions which in the past have been used for design purposes. Finally, the exact solution may be used to verify the accuracy of the finite-element type of solution. The mathematical solution on which this chapter is based was originally developed by R. D. Mindlin.l Because of the complexity and length of the solution, no attempt was made to determine the resultant stress fields until the advent of the present-day high-speed digital computer. How-

Jan 1, 1972

By R. C. Buehl, J. P. Morris

F. D. Richardson—The authors are to be congratulated on this further contribution to our knowledge of the thermodynamics of the interaction between sulphur and carbon and silicon in liquid iron. As the authors state, the influence of carbon and silicon on the activity coefficient of sulphur in liquid iron is clearly of great importance in the blast furnace, since it must cause a three to fourfold improvement in the partition of sulphur between slag and metal. The influence of increasing temperature in further increasing the activity coefficient of the sulphur in the metal in the blast furnace by increasing the carbon content is also of interest. This effect, however, is probably only part of the reason for the general observation in blast furnace practice, that the sulphur content of the metal is lowered by increasing temperature. Other contributing factors are the lowering of the oxygen potential in the presence of carbon by increasing temperature and the probable increase in the activity coefficient of the lime in the slag for the same reason. The former of these effects, which works via the (CaO) + [S] = (CaS) + [O] equilibrium, might possibly account for a 70 pct improvement in the sulphur partition and the latter might give a further 50 pct improvement. C. Sherman—I would like to compliment the authors on their very careful research. If I may, I would like to show results of calculations on the carbon-sulphur-iron system similar to the ones that were shown in our paper for the silicon-sulphur-iron system. For Fe-S-C ternary system k=PHgs/PH2 x 1/(f1°) (f2°) (%S) where fs = sulphur activity coefficient fs' = fs for Fe-S system of equal pct S f3° = f2/f2 for Fe-S-C ternary system This same analysis has been used on other systems, but the results shown in fie.- 7 are for carbon and silicon. L. S. Darken—I would like to make two brief comments in addition to complimenting the authors on an apparently very precise and accurate investigation. The first is that the present work is in agreement with a calculation by Larsen and myself." Our calculation (much less precise than the present work) was based on: (1) Unpublished work on the sulphur content of molten iron (1.5 pct at 1500°C) in equilibrium with graphite and an iron sulphide slag; (2) the distribution coefficient of sulphur between slag and carbon-free liquid iron. We expressed the result in a form equivalent to log 7. = 0.18 [%C] which gives an activity coefficient (?s.) of sulphur only slightly higher than the authors find and certainly within the precision of the earlier work. My second comment concerns the correlation of the thermodynamic findings with atomistics. A rough pic- ture of the atomic arrangement in the liquid solution is rather easily conceived for this particular liquid solution containing iron, carbon, and sulphur. Carbon has a very much stronger affinity for iron than for sulphur. Hence we may conclude that a sulphur atom will but seldom be adjacent to a carbon atom—since this would be a position of high energy. From the metallic radii of iron and carbon we know that six iron atoms pack neatly around one carbon atom. Thus each carbon atom in retaining this shell of iron atoms (which latter may not be replaced by sulphur on account of the high energy requirement) decreases the available positions for each sulphur atom by six. Hence each atomic percent of carbon decreases the equilibrium sulphur content by 6 pct (of itself). Or, at low concentration each atomic percent of carbon increases the activity coefficient of sulphur by 6 pct. This is in good agreement with the observed increase (6 or 7 pct at low carbon content). It is indeed gratifying to find a case where, by such simple reasoning, quantitative agreement is found between precise data and the modern picture of the atomistics of the metallic state. J. P. Morris (authors' reply)—We would like to point out that there is an error in the equation on p. 322 of the paper. The third equation should read: ½S2 (gas) + H2 (gas) = H2S (gas) The authors wish to thank everyone for the interest they have shown in the paper. In regard to the general observation in blast furnace practice, that the sulphur content of the metal is lowered by increasing the temperature, Dr. Richardson is correct in stating that the cause can be attributed only in part to the increase in activity coefficient of sulphur resulting from the rise in carbon plus silicon content of the metal with rise in temperature. However, this factor is probably an important one. The results of one experiment, performed since this report was written, indicate that at a constant temperature the addition of silicon to a melt saturated with carbon causes an increase in the activity coefficient of sulphur even though the carbon solubility is lowered. In this test, 2.5 pct silicon was added to a melt saturated with carbon and maintained at 1400°C. Although the carbon content dropped from 4.85 to 4.1 pct, the activity coefficient of sulphur was increased by about 20 pct.

Jan 1, 1951

By W. S. Row

This mine is operated at 4000 to 4500 tons daily through a single shaft, with one rock hoist and one service hoist. Latest shaft construction is concrete with wooden dividers. Economics of drifters and air-leg drills are compared, as well as costs of shrinkage and sub-level stoping. Economy of large haulage equipment and underground crushing is shown.

Jan 3, 1953

By Leo F. Reinartz

This is the fourth and final installment of Leo Reinartz' summation of the steelmaking industry over the first one hundred years. ALTHOUGH basic open-hearth steel has been in the limelight for many years, it has had to share some of its glory with two lesser but nevertheless important rivals, one 50 years old and one a rejuvenated process. Electric steel Electric-steel manufacture began in a humble way in the United States in 1906, when the first heat was tapped from a 3-ton Heroult electric furnace at the Halcomb Steel Co., Syracuse, N. Y. During the intervening years, it has completely eliminated the crucible process. For many years electric melting furnaces were located predominantly in relatively small, nonintegrated plants, making all kinds of high-grade alloy steels. Most of these furnaces, with capacities ranging from 5 to 20 tons, had basic bottoms. During and after World War II, many large basic electric furnaces, some up to 200 tons in capacity, were installed in integrated plants to make commodity steels. There were several reasons for building electric furnaces. Capital investment per annual ton of capacity was low and furnaces could be installed quickly. Since these furnaces used mostly scrap iron in the charge, no extra expensive coke- and blast-furnace capacity had to be added. The perfection of the top-charging design, and the development of large transformers and furnaces, made possible tons per hour as high as from modern 350-ton. open-hearth furnaces. Electric furnaces have high availability and repair costs are low. The process is flexible. Alloy and plain carbon steels of high quality can be made. Where power costs are low, the operating cost can

Jan 1, 1961

By Henry Mulryan

The largest and purest known deposit of diatomite is being actively mined and processed 3 1/2 miles south of Lompoc, Santa Barbara County, Calif., by the Johns-Nlanville Products Corporation. The workings cover 4000 acres, the depth of economically recoverable diatomite being 1000 ft. (Fig. 1). Lompoe, a community of 2500 population, is situated in the Santa Ynez River Valley 10 miles inland from the Pacific Ocean. It is 44 miles

Jan 1, 1938

By Henry Mulryan

The largest and purest known deposit of diatomite is being actively mined and processed 3 1/2 miles south of Lompoc, Santa Barbara County, Calif., by the Johns-Nlanville Products Corporation. The workings cover 4000 acres, the depth of economically recoverable diatomite being 1000 ft. (Fig. 1). Lompoe, a community of 2500 population, is situated in the Santa Ynez River Valley 10 miles inland from the Pacific Ocean. It is 44 miles

Jan 1, 1938

By S. B. Christy

The practice of the cyanide-process of gold-extraction has brought to light many important contradictions of familiar chemical analogies, which still obscure both the theory and the practice of the art with distinctions subtler and more difficult to make or follow than those which delighted the heart of the old-time metaphysician. Yet Nature herself has drawn these distinctions; and if we hope to succeed in this modern search for the Golden Fleece, we must be able to follow her through the winding labyrinth. There are so many phases of this question that I shall attempt to touch on only one of them at this time, but it is one that lies at the root of many others. In reviewing my paper on " The Solution and Precipitation of Cyanide of Gold,"* Mr. E. B. Wilson contends† that" in the solution of gold by means of alkaline cyanides the various reactions are determined, as to their order and intensity, by the relative position of the elements concerned in the electro-chemical series, or series of voltaic tension." In a modified form this statement is probably true. That is to say, the difference of electrical potential in any closed electrical circuit determines the nature of the reactions which ensue. But the matter is not so simple as Mr. Wilson assumes. Recent investigations show that the order of the metals in the electro-chemical series depends not only on the nature of the elements themselves, but also on the chemical composition of the solution in which they are placed; its degree of concentration; its temperature; and, in the case of gases, on the pressure. Unless all these conditions are taken into account, inferences drawn from the electro-chemical series are likely to prove more

Jan 1, 1901

LEAD and tin mixed together make an alloy through an attachment of natural affinity which they have with each other, so that when they are mixed it is difficult to recognize by the sight which one it is, if the essences of their qualities are not surpassed by more than half. If, indeed, one can be recognized, it is the tin which gives off a certain sharp odor to the sense of smell, besides having a greater hardness and whiteness. The best of these is the one that is the purest in its kind. In the alloy of tin it is the one that is the whitest and hardest, or, when it is bent or some thin end of it is held tightly by the teeth, is heard to crackle as frozen water does. Because this happens more with this than with other metals, I do not wish now to inquire into it. It is enough that it be a sign for recognizing when tin is pure or mixed. Pewterers say that it should be joined in alloy with lead and that it is better for working when it contains four or six pounds to the hundred because it makes it softer to the hammer and more fluid in casting. But I do not like to hear this, even if all they say is true, for I see that the tin that comes from England, when worked as well as in cakes that show it to be pure, is much more beautiful and better in all works than is that made in Venice. And I believe that it is not better for any work when mixed than when pure, except for the advantage of the master who, if he does nothing else, sells lead that is worth little for tin that is worth much. I find that when mixed it serves in only two things. One is when it is wished to make a solder for copper, for use when it is not worth while to solder the bottoms and large pieces of vessels with low-grade silver as should be done. The other is when master potters calcine it in order to make glazes and to apply white to their vases. I consider lead to be useless in all other works of any kind of metal, since it unites with none of the other metals of good company except tin.

Jan 1, 1942

By Oswald J. Heinrich

(Read at the Philadelphia Meeting, February, 1878.) DURING the last twenty years much has been done to investigate and define the Mesozoic formation of the United States along the Atlantic States, as well as in the Territories. The investigations of Professors Hitchcock, Emmons, Hayden, H. D. Rogers, and those now in progress in connection with the geological surveys of Penn-

Jan 1, 1878

Jan 1, 1913

By R. C. Hyslop

THE object of this experiment was to obtain a usable set of field curves for determining the susceptibility of rocks with the vertical magnetometer. The need often arises for determining the susceptibility of rocks in the field in order to interpret magnetic anomalies obtained. This is particularly true when diamond drilling has been done and the relation to the surface rocks of the samples taken is desired. Many methods of measuring rock susceptibility have been developed, but in general they require careful shaping of the sample or pulverizing it in addition to delicate laboratory measuring instruments designed for the purpose. The requirements for a practical method for the determination of susceptibilities are as follows: I. There should be as little alteration as possible of the specimen. 2. A minimum of time should be required in the preparation of the specimen and the calibration of the equipment. 3. The equipment used should be portable. 4. An accuracy within the limits of the survey at hand should be obtainable. 5. A means of measuring the remnant magnetism should be available. LABORATORY PROCEDURE With these ideas in mind, the problem was approached in the manner in which Koenigsberger1 developed his method using the principle of the electrical theory of images of Lord Kelvin and applying it to the magnetic case. This solution of the problem states that the apparent change [ ] in the magnetic field intensity due to the proximity of a specimen is given by: [ ] Where k is the susceptibility of the specimen, m the strength of the pole of the needle, and a its distance from the surface of the specimen, as shown in Fig. I.2 This relation is true only for an infinite body and corrections are necessary for a finite body. Koenigsberger used in his work a variometer of special design. He suggested that a Schmidt vertical balance or horizontal magnetometer, as well as some other instrument, might be used. The Colorado School of Mines horizontal torsion magnetometer operates on this principle. In the

Jan 1, 1941

By James Marsh

INTRODUCTION Economists have long expressed suspicion of the economic theory of natural resource exhaustion, even in writing articles which have contributed to it (1). Indeed, the gap which separates the pure theory from practical management seems unusually wide. It is doubtful whether a mine manager could possibly know enough about the relevant parameters of his mine to steer it along the optimal paths described by the theorists (2). Nevertheless, enough faith in the theory remains that mine managers are suspected of being a separate breed whose behavior must be studied in special courses using specialized text-books, collections of readings, and journals (3). The implied hypothesis, that mines and natural resource firms are managed differently than other firms, is the subject of this paper. In the next section the theory is developed and analyzed. In section III, I discuss the implications of the statistical results that have been obtained. Finally, conclusions are reserved for section IV. THE MODEL A key difference between the traditional theory of natural resource production and that of other forms lies in the set of variables which ire assumed to jointly determine the quantity of output the firm will produce. Output, in the non-resource case, is assumed to be a function of k clearly definable and distinguishable inputs or factors of production, viz., y = f(xl, x2, ..., xk), (1) here

Jan 1, 1977

By Donald L. Birkimer

GENERAL INTRODUCTION To paraphrase comments made by Black and Hoek(1) on the status of rock mechanics, the general methods of applied science related to rock mechanics are: a. Observe the phenomena of nature as they occur and, wherever possible, quantify the observations. b. Propound a model or theory to explain the phenomena observed. c. Test and develop the theory by further experimentation in the laboratory and in the field. d. Use the theory developed to predict behavior in similar or extended circumstances. e. Insure by measured experiment and observation that the predictions made are valid, or that deviations from the predicted behavior can be accounted for. f. Modify the theory and practice as necessary, and continue the process until more general laws can be formulated and applied, with a useful degree of confidence, to practical problems. This paper will present an infant concept. It will, in fact, propound a possibly useful theory to help explain commonly observed phenomena. It will test and develop the theory for a material similar in nature to some rocks. It will be used to predict behavior in the extended circumstances of a

Jan 1, 1971

By F. C. Blickensderfer

DURING 1914 and 1915 extensive experiments were conducted at the concentrator of The Detroit Copper Mining Co. of Arizona, at Morenci, Ariz., in order to test the relative grinding efficiencies of the Marathon, the Chilean and the Hardinge Mills. The Marathon mill used in the experiments was the first one ever built by the manufacturers; and since this was the first time that it was given a thorough tryout, with such remarkable results, the data have been, assembled in the following paper and submitted in the interests of the milling profession.

Jan 8, 1916

By S. C. Lee

An uncoupled thermoviscoelastic finite element formulation with an application to Underground Coal Conversion (UCC) is presented. An incremental solution procedure with an implicit time stepping scheme is used under the thermorheologically simple material (TSM) postulate. The presented formulation, for a homogeneous and isotropic medium, is employed in the simulation of the UCC post-burn phase. Temperature, displacement, stress, and failure responses under thermomechanical loading are predicted. The solutions for the selected field problem indicate potential roof collapse, stress relaxation, and modest surface subsidence with a progressive thermal and failure front. The corresponding thermoelastic responses with temperature- dependent elastic properties are also presented and compared with the thermoviscoelastic results.

Jan 1, 1984

By A. M. Gaudin, T. P. Meloy

This paper presents the theoretical derivation of the distribution equation for single fracture. The equation is shown to accord with experiment. Several empirical size-distribution equations have been proposed to describe the size of broken materials. Among them are the Gaudin-Schuhmann equation and the Rosin-Rammler equation.3*4 The Gaudin-Schuhmann equation relates the relative fraction of undersize to relative size —. In this relationship Mo is the total weight of crushed sample, M(x) the weight of undersize contained, x the size considered, K a quantity called the size modulus, which together with the slope parameter, m, characterizes the product. The slope parameter is usually close to unity. The Rosin-Rammler equation relates the same relative fraction of undersize to the relative size modulus by an equation of different form In this relationship, e is the base of natural logarithms. In the fine size-range when m is unity both equations give Gilvarry and Berstrom have sought a size distribution equation having a sound theoretical basis. They have come to an equation taking into account the effect of volume, surface and edge flaws in fragmentation. If the effect of the volume and surface flaws is neglected, the equation taking only edge flaws into account has the form of the Rosin-Rammler equation. In the present paper, a theoretical size-distribution

Jan 1, 1962

By B. Etkin, A. A. Haasz

The Infrasizer Mk III, developed at the University of Toronto, is capable of sizing particles of a few pm to hundreds of pm according to particle terminal velocity, which is a function of particle density, size and shape. The factors limiting the performance of the Infrasizer Mk III have been presented and analyzed. It has been established theoretically and experimentally that the device has excellent potential as a laboratory instrument. The principle is applicable to a continuous production classifier, a prototype of which is now under development.

Jan 1, 1980

By Carroll C. Bailey, William F. Boericke

Mine financing, or providing adequate capital for developing and bringing a mining property into production, is an essential requirement for a successful operation. Today it presents a different picture than even twenty-five years ago. The day appears to be gone when a mining property could pay its own way from grass roots to production. The country has been quite thoroughly combed for surface showings from which sufficient initial profit could be immediately garnered to pay for further development and production facilities. The four M's for success in mining-mineral, market, management, and money-are still essential, but doubled or tripled wage costs and steep advances in cost of equipment and supplies throw increased emphasis on adequate capital funds for converting a prospect into a producer. Consequently, the old picturesque, although seldom rewarding, grub- staking procedure where a single venturesome citizen might advance funds to a prospector on a fifty-fifty basis for whatever discovery he might find, has largely disappeared. Its place, to some degree, has been taken by the small syndicate of venturesome members who band together for furnishing funds to a group of prospectors for the same general purposes. Such a syndicate has a definite organization and is usually assured of sufficient initial funds, or flow of funds, to carry on work for several years. It is usually headed by an engineer-promoter or an entrepreneur trader who has had considerable field experience as well as personal knowledge of his prospecting crews. For the owner of a potential mining property who has ample capital, the problem is to determine (1) justification for the necessary investment in exploration and development, and (2) the economics of the enterprise as to size and degree of integration of the ha1 operating entity. If the owner of such a property has little or no capital, he also faces these same basic problems but, in addition, must be able to present the findings of fact and persuade the prospective investor that the enterprise will produce

Jan 1, 1964

By P. Somasundaran, G. E. Agar

The role of calcium, phosphate, and fluoride species in determining the zeta potential of apatite in aqueous solutions was investigated in this study. The zeta potential of apatite was determined by streaming potential measurements over a wide range of concentrations of potassium nitrate, calcium nitrate, potassium dihydrogen phosphate, and potassium fluoride solutions at various pH values. While the addition of phosphate made the apatite surface more negative at all pH values, calcium caused a significant increase of the zeta potential only when the zeta potential was negative. Fluoride addition had only a minor effect on the zeta potential, but both negative and positive values were increased.

Jan 1, 1973