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By Morris Cohen, Robert C. Ruhl

The phases in Fe-C alloys over a wide composition range have been studied after splal quenching from the liquid state. Binary alloys containing 0 to 5.1 wt pel C as /cell as a large number of ternary Fe-C-Si alloys with 2.5 to 5.0 wt pct C and 0.3 to 5.1 wt pct Si were attlong those sludied. Olher Fe-C-X alloys, zcilh X being Co, Cr, ,Wn, Ni, and Ru , were also inrestigated after splat quenching. At high carbon contents, a new hcp phase (designaled 6 phase, but different from e carbide) is retained upon splat quenching. The .fraction of this phase varies up lo 97 pcl for a Fe-4.K-1.9% alloy. The composition of the E phase ranges from about 3.8 10 4.8 wt pet C, and the corresponding laltice parameters increase linearly ulith carbon content, while the c/a ratio remains essentially conslc~nl. The E phrtse appears to he a solulion of carbon in E iron, the latler being nornially found only at high pressures. It is deduced that the unit cell of the E phase corresponds to the formula Fe12C3, and llzal il is relaled to tlie ordered slruclures 0.f 6 iron carbide and c iron nilride. The E phase is compared and contrasted to the olher known carbides and nitrides of iron and nickel. An exlrapolaTion of the atomic volume 1,s carhon conlent of /he E pllase lzcts giz.en a neu7 estitnale jor /he alomic volume of E iron, 11.30 cu A, a1 atmospheric pressure and temperature. Other alomic volume relalionships lead to /he co~zpositioti Fe2.iC tor E iron carbide, /he unit cell fortr~ula being -Fe2rClo The E phase undergoes a lulo-slage decomposition upon healing, .forrning firsl rnarlensile plus E carhide, a/ler 1 hr at 140" lo 200°C, slid then ferr ite Plus cementile, after 1 lir a1 330" to 460°C. A1 carbo,l contents between 1.5 and 3.0 LC/ pcl, (he predo.wirzar/t plzase alley quenching is fcc austenite. The retained carbon content of this phase increases with itlcreasing silicon in certain concentration ranges, reaching a maximum of 2.37 wt pct C itz a Fe-2.6C-4.OSi alloy. This is the highest carbon conten1 reLaitled in austenite to date. These high-carbon aus-tenites can be partially tm?zsforttled lo tnartensile hy severe deformation in the temperature range of — 190 to -50°C. TECHNIQUES for splat quenching from the liquid state have been utilized in numerous recent investigations to produce metastable phases in a variety of alloy systems. Among the several ways of splat quenching, the shock-tube method appears to yield the highest cooling rates1-3, 7, 8 and was adopted here. Estimated cooling rates attained in the present experiments ranged from 10' to 10 80Cper sec.' As a part of a research program on interstitial al- loy phases, the Fe-C system was selected for splat-quenching studies. It was hoped that splat quenching would allow high metastable supersaturations of carbon to be retained in solution. Also of considerable interest were the conditions governing the occurrence of the various intermediate phases upon solidification. The alloys investigated included both binary Fe-C compositions as well as six ternary Fe-C-X alloy systems. The known phases in the Fe-C system are summarized in Table I.* Only the ferrite and graphite are ent investigation.14 and is described in detail herein Table II summarizes corresponding data on Fe-N phases, which are also of interest here because of their similarity to the Fe-C phases. EXPERIMENTAL PROCEDURES Alloys were prepared by melting the elements. 99.9 pct purity, in an inert gas nonconsumable electrode arc furnace. The buttons. weighing about 5 g. were remelted twice. were then fragmented. and their interior surfaces were examined for uniformity: if any doubt existed. they were remelted again. Chemical analyses were performed on all the alloys. the accuracy being about k0.05 wt pct. At high temperatures, carbon-containing alloys react with alumina crucibles as follows: If the atmosphere in the splat-quenching furnace does not contain sufficient carbon monoxide the alloy can be depleted of carbon and contaminated with aluminum. Calculations and experimental observations showed that 50 to 100 torr CO partial pressure effectively blocked the above reaction in all the alloys investigated. The splat-quenching equipment in Figs. 1 and 2 provides for evacuation and back-filling with CO-Ar mixtures. The furnace is capable of operation up to 1650°C. and the gettering action of the graphite heating element reduces the oxygen partial pressure in the furnace atmosphere to below 10-5 torr, thus preventing oxidation of the specimens.

Jan 1, 1970

By Ernest F. 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 fluorspar 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. Arizona Fluorspar has been reported as occurring in Arizona in the following localities: near Duncan, Greenlee County; near Naco, Tombstone, and Paradise, Cochise County; Black Mountain, Mojave County; 25 miles southwest of Tucson, and at Helvetia and Silver Bell, Pima County; near Mammoth mine, Pinal County; in Yavapai County, 7 miles from Aguila, and in the Bradshaw Mountains; and near Dome, Yuma County. Production has come principally from the Castle Dome district, Yuma County, with minor quantities from Greenlee, Pima and Yavapai counties. The writer examined deposits in the Castle Dome district, Yuma

Jan 1, 1934

By Charles Clayton

CAST-STEEL runners, while not interesting from a commercial standpoint, furnish valuable material for microscopic study. Foley1 found not only the usual ingot structure, but zones of Widmannstattian structure, which he explains as due to differential crystallization. The writer, in examining nickel-steel runners, found a type of pro-eutectoid ferrite that is unusual and most probably new. The runner in question was 8.75 cm. (3.5 in.) in diameter and analyzed at its center 2.69 per cent, nickel and 0.350 per cent. carbon and at its edge 2.62 per cent. nickel and 0.359 per cent. carbon. The macrostructure, which is the usual type, is shown in Figs. 1 and 2, which are a cross-section and the longitudinal surface, respectively. Slight segregation of ferrite can be seen near the center of the segment and at other points near the edges of polyhedral grains. Stead's reagent brings out the dendritic structure within the grains as shown in Figs. 3 and 4. This texture is what would be expected of such a steel. Figs. 5 to 10 show the peculiar swirls of pro-eutectoid ferrite, the finding of which prompted this paper. These swirls, or eddies, if such a term can be applied, occur in all parts of- the runner and in all parts of the individual grains. I he tipper left-hand figure shows this ferrite at a grain boundary; the middle left-hand figure shows the inner portion of a grain; and the lower left-hand figure shows these swirls at the edge of a grain which is also the outer edge of the runner. Straight-lined ferrite associated with swirls is found in the areas of Figs. 11 and 12. The texture of the carbon-bearing constituent of the runner is shown to- some extent in Fig. 12, the pearlite being very fine or sorbitic. Higher magnification does not bring out any new features either in the peculiar ferrite or in the pearlite. Figs. 13 and 14, at 240 diameters, show the curved and straight-lined ferrite.

Jan 3, 1920

By F. C. Bond

Since the Third Theory of Comminution was presented eight years ago (I) it has found increasing use in crushing and grinding problems. The practical utility of its wok index equation is quite generally acknowledged (2). However, its theoretical basis has been questioned in at least three technical articles (3) (4) ('). The purpose of this paper is to present experimental proof that it is scientifically correct. Particles under compressive stress are strained and deformed. They absorb strain energy, and when this locally exceeds the breaking strength, a crack tip forms. The surrounding strain energy flows to the crack tip, which rapidly extends and splits the rock, releasing the strain energy as heat. The initial energy flow causes additional crack tips in highly strained areas. If the compression is rapidly applied by impact, crack tips may form before the strain energy has reached equilibrium in the particle, thus decreasing the total work input required for breakage. The energy necessary to break is essentially the energy necessary to produce crack tips, since the energy necessary to extend the cracks to breakage is already present as strain energy in the deformed particles. After breakage nearly all of this energy appears as heat. The crack length cannot be measured directly. However, in particles of regular and similar shape the crack tip length is considered as equal to the crack depth, or crack extension necessary to break, so that the crack length equals the square root of one-half of the surface area. The Third Theory states that the useful work done in crushing and grinding is directly proportional to the total length of the new cracks formed. It can be confirmed by showing that a constant work input produces a constant length of new cracks when reducing the same material to different product sizes. This is done in the present paper on a wide variety of material. The constant work input was supplied by one revolution of the 12" x 12" laboratory ball mill used in making grindability tests by the Allis-Chalmers method (12) (13) The new crack lengths produced per mill revolution were measured from all available grindability test results at 28, 35, 48, 65, and 100 mesh on fifteen different ores, and were found to remain substantially constant for each ore at all mesh sizes. A new technique is used for the measurement of crack lengths. Size distribution plots of the mill feed and product are made by the Third Theory method (9) and the crack lengths are obtained from these plots by the procedure described in the present paper. The energy input required to produce a unit length is of fundamental importance in the size reduction of brittle solids. The crack length Cr is expressed in centimeters per cubic centimeter of solid material. It bears a definite relationship to the external surface area of the crushed or ground solid. A uniform particle shape must be assumed before the surface area and crack length can be evaluated. In this paper it is assumed that the relationship between the surface area and the particle volume of a particle d microns in diameter is the same as that of cube d microns on a side. The external surface areas of particles with a cubical breakage probably agree approximately with this rule, and correction factors can be applied when physical measurements of the surface areas are available for comparison. However, the assumption of equivalent cubes has been found satisfactory for most calculation purposes. Assuming equivalent cubes, one cubic centimeter of particles d microns in diameter will have a crack length Cr of v30.000/d centimeters, and a surface area of 60,000/d square centimeters. The specific crack length is thus equal to the square root of one-half the specific surface area. Where Sa is the surface area in square centimeters per gram and Sg is the specific gravity of the ground solid, then Cr = vSg . Sa/2 = 173.2/ vd (1)

Jan 1, 1961

DAVID WHITE,* Washington, D. C.-This paper is very timely since the Philippine Islands are presumably open to the enterprise of the American driller, whereas much of the territory in that part of the world is closed to us. The United States has ambitious plans for the operation of a great merchant marine, which is to be oil burning in the main, and it takes but a glance at the world map to see the strategic advantage of oil supplies in the Philippines for such marine operations. It is a little difficult to understand why more attention has not been given to the Philippines, in spite of the difficulties attending development in these islands. A number of American oil companies are, I believe, at the present moment taking an interest in the possibilities of the Philippines. Important factors in the formulation of opinion regarding the importance of the oil deposits of the Philippines, as brought out by Mr. Pratt,1 are the point of view and the breadth of experience of the examining geologist. The average oil geologist, whose experience has been mainly in the Appalachian region, the Mid-continent, or Louisiana, or possibly even in California, on seeing the narrowness of the basins, the closeness of the folding, and the presence of igneous rocks here and there, would be likely to draw unfavorable conclusions as to the possibilities of the Philippine Islands. Geologists visiting that region should be familiar with the geological conditions of oil occurrence in Japan, Formosa, the East Indies, or in the Baku district, and their conclusions should be formulated with the knowledge and understanding of the occurrence of oil in those regions rather than in the United States.

Jan 8, 1920

By R. W. Raymond

THE absence of a convenient glossary of terms connected with mining and metallurgy has long been felt by the general public. It is to meet this want, not to furnish a technical manual for experts, that the following glossary has been prepared. It originated in an attempt on my part to revise for publication the manuscript of a compilation prepared from the appendix of Yale's work on Mining Titles and one or two other sources, to serve as an appendix to a new work on mining law, about to be published by Mr. H. N. Copp, of Washington, D. C. This revision soon assumed, contrary to my original intention, the proportions of a reconstruction; and with the consent of Mr. Copp, and for the purpose of receiving from my fellow-members valuable aid, I presented my still incomplete work as a paper at the Lake Superior meeting of the Institute, inviting from any quarter suggestions of new terms or better definitions to be incorporated in the glossary before its final publication. This invitation was so widely and generously responded to, that I cannot undertake to make in this place individual acknowledgments to those members of the Institute, and professional colleagues outside of it, who have favored me with assistance and advice. The labor bestowed upon this paper since its presentation at the Lake Superior meeting has considerably exceeded that of its first preparation, as may be inferred from its great increase in length, as well as the numerous alterations which it has undergone. It could certainly be still further enlarged and improved; but I think a comparison of it with any of the glossaries of the same class now in print will show, at least, that it is an advance upon what has hitherto been accomplished. 1 shall be grateful, however, for further criticisms and suggestions; and I purpose at some future time to incorporate in a supplementary paper the results of such additional collections or corrections as I may obtain. To avoid too great prolixity, I adopted at the outset the following general principles: 1. To include the most important technical words and phrases used by American miners and metallurgists, or occurring in English books and periodicals.

Jan 1, 1881

By Eugene Guccione

FOREWORD-At the SME-AIME meeting in Las Vegas this year, the SME Publications Board and the MINING ENGINEERING Committee decided that a fitting way of celebrating the United States' bicentennial would be to publish an article in ME covering the great men in American mining. After some discussion as to the inclusion of financiers -men such as William Randolph Hearst, J. Pierpont Morgan, etc.-the group agreed that the feature should be restricted to the "nuts-and-bolt people," e.g., mining engineers, geologists, mineral processing engineers. Thus, from the AIME All Institute Honors roll and from the SME Awards list, the group chose these 11 historical figures: Herbert Hoover, Daniel C. Jackling, Henry Krumb, James Douglas, Rossiter W. Raymond, Hal W. Hardinge, Seeley W. Mudd, Erskine Ramsay, Howard N. Eavenson, Robert A. Richards, Arthur F. Taggart. What follows is an account of each of these great miners' achievements and the problems they faced, and an assessment by some of today's mining leaders of the challenges that lie ahead.

Jan 7, 1976

By H. Rush Spedden, A. M. Gaudin

ALTHOUGH the number of minerals that are ferromagnetic) or highly paramagnetic is strictly limited, it has been known for some time that many minerals have slight but supposedly characteristic magnetic susceptibilities. With the exception of pyrrhotite, however, sulphides have been thought nonmagnetic. A new magnetic separator has been made available recently in limited quantity to research laboratories. This device, the Frantz Isodynamic Separator, has been used for the separation of various nonsulphides from each other. Its application to the separation of sulphides, however, does not seem to have been reported. In the Richards Mineral Dressing laboratories, the success achieved through the use of this device in separating associated sulphides has been so startling as to lead us to believe that it constitutes a magnificent adjunct to heavy-liquid separation and to quantitative mineragraphy as a tool for the mineral investigator. THE SEPARATOR The separator (Fig. I) consists of: I. A powerful magnet, the strength of which can be adjusted by means of a rheostat; 2. A vibrating chute of nonmagnetic metal on which the mineral to be separated is made to flow (Fig. 2); 3. A feed bin and adjustable feeder; 4. Receptacles for the collection of products; 5. Means for changing, setting, and accurately reading the two slopes of the chute; viz., the cross slope and longitudinal slope. The separator is made operative by the special shape of its pole pieces, which ensures a strongly converging field. It is said by the makers of the machine that the pole pieces apply a constant mechanical force to a particle of given susceptibility, regardless of its position in the operating space of the separators.* Susceptible particles, therefore, behave as though of lower specific gravity than under ordinary circumstances. This effect, combined with the slopes of the chute and the action of the vibrator, causes a stratification not unlike that obtainable on a shaking table. The chute is of rectangular cross section, and shallow; it is broadened toward the discharge end and divided longitudinally by a partition into two compartments that lead to the collecting receptacles. Although the separator probably can be used to make separations at fairly coarse

Jan 1, 1943

By Andrew Cosgarea, William R. Upthegrove, Morteza Mirshamsi

The capillary-reservoir technique was used with lead-210 and cadmium-115m to determine the self-diffiLsion coefficients of both cadmium and lead in the liquid binary Cd-Pb system. The self-diffusion coefficients of pure cadmium and pure lead were obtained and were compared with the theoretical predictions. Good to excellent agrement between the experimental and predicted values was obtained. The self-diffusion coefficients of cadmium were tneasuved in alloys containing 2.50, 9.13, 17.40, 31.00, 45.00, 69.00, and 97.00 lot pct Cd by determining- the amount of cadniiutn-115m which diffused out of a small-bore capillavy into an infinite reservoir during- a given time peviod. Sinzila7-measurements were made with lead-210 to determine the self-diffusion coefficients of lead in these identical alloys. Diffusivities were determined from measurenzents performed in the temperature interval of 290" to 480°C. The results were correlated with the Ar-vhenius equation, and the maximum variation of the equation parameters (Q and Do) was also inrestigated . THE theory of diffusion in liquids, particularly liquid metals, is relatively undeveloped in contrast to that for the gaseous and solid states. Although the practical application of liquid metals as heat-transfer media has become increasingly important, few liquid-metals systems have been investigated. Experimental data of fundamental significance in this field are not readily obtained, which may explain but not justify the present lack of knowledge. What work has been completed is primarily restricted to liquid diffusion of pure metals; little work has been done in liquid-metal diffusion of binary mixtures. A review of liquid-metal diffusion theory and research is available elsewhere.1-4 In an effort to add to the knowledge of liquid-metal systems and to increase the basic understanding of the diffusion process in liquids, a study of diffusion in the binary-liquid system, Cd-Pb, was undertaken. The capillary-reservoir technique5 was employed to measure the self-diffusion coefficients of cadmium and lead in molten binary alloys. Measurements were made with seven selected compositions and over a temperature range from 290° to 480°C. The experimental apparatus consisted essentially of the following items: constant-temperature bath, diffusion cells, capillaries, capillary-filling device, and a radioactive tracer counting system. EXPERIMENTAL APPARATUS Constant-Temperature Bath. A cylindrical steel vessel, 8 in. in diam and 15 in. deep, surrounded by an insulated heating coil was used with a sodium-potassium nitrate salt mixture heating medium. The bath was maintained slightly below the desired control temperature by the furnace-heating element; and a 250-w heater, actuated by a Bayley proportional temperature controller, was utilized for the final control of the temperature. A constant-speed mixer stirred the salt to insure a uniform temperature within the bath. Four calibrated Chromel-Alumel thermocouples were placed at various positions in the salt bath to verify the absence of temperature gradients. The observed temperature variation during any diffusion run was less than 0.l°C. The entire furnace assembly was mounted on four shock absorbers to exclude building vibrations and the stirrer propeller blades were adjusted so not to induce vibrations within the reservoir. A schematic diagram of the furnace and the constant-temperature bath is shown in Fig. 1. Diffusion Cell. The diffusion cells and associated parts were the same, except for slight modification, as the one used by walls1 in this laboratory, and are shown in detail elsewhere.' A graphite crucible, 4 in. long and 40 mm (1-1/2 in.) ID, enclosed in a 60-mm (2-1/4 in.) Pyrex tube cell about 18 in. long, was used as a container for the melt. The reservoir (molten alloy in the graphite crucible) was usually about 2 to 2-1/2 in. deep. Graphite was used because of its satisfactory nature as a refractory material and the low solubility of carbon in molten Cd-Pb alloy.677 The Pyrex cell was closed at the bottom and fitted at the top (open end) with a 2-in. Dresser coupling. A brass flange was welded to the top of the coupling. The upper part of the diffusion assembly was bolted to this flange with an O-ring seal. The lower part of the diffusion cell was supported in a 3-in. brass cylinder which was open to allow for circulation of salt around the cell. The top assembly consisted of two synchronous motors, a drive shaft, a thermocouple well, and controlled-atmosphere inlets and outlets. One motor was used for rotation of the capillaries at a rate of 1/2 rpm in the reservoir during the diffusion run. The other motor was used for the vertical positioning of the capillaries and the capillary holder by means of a simple screw drive. The capillary holder and drive assembly were lowered into the reservoir for the run and raised after the desired diffusion time at a rate of approximately 0.4 in. per min. Capillary holders were made of graphite. These

Jan 1, 1967

By G. D. Van Arsdale

This paper describes a series of experiments leading to the development of a method for leaching the mixed ores of the Inspiration Consolidated Copper Co., containing chalcocite and silicates of copper, by the use of solutions acidified with sulfuric acid and carrying ferric sulfate. Iron is added to the solutions and ferric iron is regenerated electrolytically to a percentage high enough to act as an effcient solvent. The decreased yield is partly compensated for by a higher current density. An important problem in modern copper metallurgy, particularly in the Southwest, has been to obtain good recoveries from what are commonly known as mixed ores; that is ores in which the copper occurs partly as oxide and partly as sulfide compounds. The dividing line between mixed ores and ores commonly accepted as concentrating is not definite. In other words, much ore now being concentrated carries considerable copper in non-sulfide form, on which recoveries are not so good as on ores carrying less of these constituents. While treatment by concentration may be commercially profitable on ores carrying oxide copper within certain limits, there are large deposits for which the application of concentration could not be considered, and yet which have not been considered amenable to leaching because they carried too much sulfide. The Inspiration Consolidated Copper Co. has large amounts of such mixed ores, and this paper is an account of the experimental work by which a method was developed for their treatment, and for which a large plant is now being erected by the Inspiration Co. It is not claimed that the method is a general solution of the problem of mixed-ore treatment but it is apparently well adapted for leaching the ores of the Inspiration Co., for which it was designed. The work done has covered preliminary laboratory and test-plant investigation, and a pilot-plant run, extending from March to the middle of December, 1923. Thoroughly consistent and satisfactory results were obtained continuously for more than six months in the pilot plant; and it is believed that the results and probable costs that can be had on a large scale have been definitely proved. The method, however, was designed for local conditions; and while the basic principles are general, there are ores on which it will not work and other ores for which considerable modification may be required.

Jan 1, 1926

By A. M. Gaudin

THE study that is presented here was undertaken in order to condense information concerning comminution, and covering a great variety of conditions, into one or several rules which would be of use in the development of a systematic theory as well as in many directly practical ways. As the result of this work, the following conclusions appear justified 1. Rocks may be classified, from the point of view of comminution, into two general classes which are (a) structurally homogeneous, and (b) structurally heterogenous. Structurally homogeneous rocks are those in which fracture takes place through grains and grain boundaries alike; heterogeneous rocks are those in which fracture passes in preference through grain boundaries. 2. If a sized product composed of structurally homogeneous rock grains is crushed, a product results in which the relation between the percentage weight of grains of various sizes and these sizes themselves follows a definite law. This is not true of structurally heterogeneous rocks. 3. Ball milling with structurally homogeneous rocks, and under certain conditions, presents exceptions to this rule. 4. In ball milling with structurally homogeneous rocks, there exists a critical ratio of size of feed to size of balls, above which the machine operates essentially by surface wear, and below which it operates essentially by breaking across the body of the particle. 5. In ball milling, with structurally homogeneous rocks, and when the size of feed grains exceeds the critical size, the particles worn off are of a, substantially definite size which depends upon the ball size 6. In the case of a typical heterogeneous rock, such as Manhattan schist, particles are crushed in such a way that there is a greater proportion of grains of the size that is the average grain-size of the rock than there would be in that range of size with a structurally homogeneous rock. This has been found to be true with-all the crushers tested. 7. Different methods of crushing produce grains of different shapes.

Jan 2, 1926

By Charles R. Keyes

Prefatory,........323 Foundation of classificatory schemes in general..325 Past opinion on the classification of ore-bodies,.326 Nature of ore-deposits,....... 326 Definition........326 Fundamental law of origin.... 327 Significance of ore-bodies,.... 327 Date of origin........328 Original source of ores..... 328 Alteration of ore-bodies,....329 General methods of ore-formation.... 330 Ascension verm lateral secretion... 330 Replacement.......330 General factors in classification....332 Genesis in ore-classification....332 Literature of ore-deposits...... . 333 Criteria of ore-classification,..... 335 Primary grouping of ore-deposits..... 338 Hypotaxic deposits......341 Eutaxic deposits...... 341 Ataxic deposits....... 313 Secondary categories of ore-bodies....343 Ternary phases of ore-deposition.....344 Types of hypotaxic or surface deposits..... 344 Illustrations of eutaxic ore-bodies.... 347 Examples of ataxic ore-bodies.....352 Recapitulation.. .. .. .. 355 Prefatory. Much has been written on the genesis and classification of ore-deposits. Much remains yet to be written on the subject

Jan 1, 1901

By G. Willard Quick

FAILURES in railroad rails have been of vital concern to engineers; railroad executives, rail manufacturers and the general public for years. Failures from transverse fissures originating from internal nuclei have received particular attention in the past 20 years. Dr. J. E. Howard first reported this type of failure in 1911, as being responsible for a wreck-on the Lehigh Valley R. R. in which several lives were lost. Since then many transverse fissures have been found. In 1919, Waring and Hofammann1 etched longitudinal sections of rails in hot acid and found cracks extending both longitudinally and transversely in certain used rails as well as in some new rails.. Since then it has been thought by many that these "shatter" cracks are the nuclei from which transverse fissures subsequently develop in service. Methods for reducing the rate of cooling rails on the hot. bed have been devised to decrease the temperature gradient and consequently the stress gradient in the rails. A study of the tensile properties of rails at elevated temperatures was made by Freeman and Quick,2 who investigated the properties at temperatures through which rails pass on the cooling bed after leaving the hot saw. In their investigation a special study was made of the ductility of the steels in the temperature range 400° to 700° C. In this temperature range it was found that certain rail and other steels showed a marked decrease in elongation and reduction of area. The phenomenon was called "secondary brittleness" and the temperature range the "secondary brittle range." A tentative explanation was presented that internal failure such as "shatter cracks" and "hair cracks" in rails are the result of thermal stresses developed in the steel structure while cooling through the secondary brittle range. The investigation showed that the magnitude of the phenomenon varies for different heats, but that it did not differ for specimens from different ingots or for different rails in a particular ingot. It was also shown that annealing rail steel at a temperature either above or below the critical

Jan 1, 1932

By A. Becker, J. A. Slankis

Equipment has been developed to utilize natural 8 Hz electromagnetic fields to measure rock resistivities. Telluric and magnetotelluric surveys have detected resistivity variations associated with geological contacts and metallic sulfide deposits. The fundamenfa1 premises of these methods are illustrated by the results of surveys across a Pleistocene-Precambrian contact in the Ottawa Valley and a near-surface sulfide deposit in Northern Quebec. Such interfaces are characterized not only by variations in apparent resistivity, but also, unexpectedly by the spatial anisotropy of the electric fields and the presence of a strong vertical magnetic field component in their vicinity. Standard geophysical electrical and electromagnetic methods (Heiland, 1940) for the determination of the electrical properties of the ground and the search of good electrical conductors necessitate the use of a transmitter and receiver which are coupled galvanically or inductively through the ground. The electrical properties of the ground are deduced from either the transfer function, or the impulse response, of the transmitter — ground — receiver system. Where deep penetration is desired these methods require powerful transmitters whose weight and size increase the cost and reduce the speed of operation. It is possible however, to resort to another class of electrical prospecting methods which employ ambient, natural electromagnetic fields in place of a transmitter.'-' In the audio and subaudio frequency ranges, these fields are generated by thunderstorm activity. At some distance from the seat of the disturbance, the e.m. fields propagate as plane waves with a horizontal magnetic field component. The incident wave, of course, induces currents in the ground. Where the ground is homogeneous the relation between the horizontal magnetic and horizontal electric fields vectors is particularly simple:' /E/ = \[SpT/H/ (1) where: /E/ = magnitude of horizontal electric field in millivolts/kilometer (RMS) /H/ = magnitude of the orthogonal inducing magnetic field in milligammas (RMS) p = rock resistivity in ohm-meters i = frequency of measurement in c/s In practice, the ground is seldom an homogeneous half space, lateral conductivity variations exist, (in the case of base metal prospecting these are the features actually sought) and the two field vectors are no longer simply related. The ratio of E to H is still useful, however, for the determination of an "apparent" ground resistivity. From a theoretical view point, the general problem of a two dimensional fault or dyke anomaly can be separated into two distinct cases. In the first case, where the e.m. energy propagates in a direction normal to the strike, the horizontal magnetic field remains constant and is oriented along the strike of the formation.3 As shown by d'Erceville and Kunetz," all the information about the anomaly is contained in measurements of the electric field component. In fact, away from the interface, the electric fields are proportional to the square roots of the resistivities:

Jan 1, 1970

By J. J. Rutledge

I. DESCRIPTION OF THE CLINTON ORES AND ASSOCIATED POCKS. THE Clinton rocks in Stone Valley comprise (1) thick layers of deep-red shale, (2) layers of reddish-gray shale interspersed with beds of sandstone and thin beds of extremely fossiliferous limestone, and (3) yellowish-gray shales alternating with thin layers of olive-colored shales. These layers of shale are all very thin and are at no point massive.1 A bed of gray-white sandstone varying in thickness from 12 to 30 ft. occurs in the tipper portions of the Clinton shales. This is called the ore sandstone, a name given to it by Rogers and adopted also by the Second Pennsylvania Geological Survey. It is the surest guide to the presence of the iron-ore bed, which lies below its lower edges at distances varying from 10 to 20 ft. This ore sandstone, in the valley, lies generally at very low inclinations, but often is locally subjected to considerable changes in dip. At its outcrop this ore sandstone weathers very easily and yields a rather sparse crop of stone, Composed of dirty, iron-stained boulders. Upon the roads these boulders are quite well rounded, and bear fragments of crinoid stems and other fossil forms. The ore sandstone exhibits at many points evidences of former movements in this very great thickness of the shales, and as it is the only stratum in this series competent to transmit and record stresses due to structural movements, its evidence is of considerable importance in determining the occurrence of movements in times past.

Nov 1, 1908

By R. E. Zimmerman

THE separation of fine sizes of coal from its impurities by means of various flotation methods has become of increasing importance in the coal industry. This, no doubt, will be even more so in the future as the quantity of high grade coal is depleted, particularly that used for metallurgical purposes. The purpose of this paper is to describe and report the results of research work done under the auspices of the Pittsburgh Coal Co. to determine the amenability of their bituminous fine sizes of coal to flotation, to investigate the value of various reagents and factors affecting their use, and compare the results between froth flotation and bulk oil flotation. Compared with the preferential flotation of complex minerals, or ores, the flotation of coal is comparatively easy. However, this statement should not lull one into the feeling that there are no special problems involved. For instance, the separation of coal from pyrite in high sulphur coals is still far from being 100 pct successful. Size consist has considerable effect on reagent consumption and recovery. Other factors will be described and finally it must be remembered that in the flotation of coal a low priced material is being treated and thus economic considerations govern more closely its application than is generally the case in treating other minerals. As a result of the research work done by the Pittsburgh Coal Co. on the flotation of coal, it was concluded that it was practical to clean the -48-mesh coal commercially by froth flotation and after several different types of flotation units and circuits were investigated by means of pilot plants, large scale units were installed at their Champion Nos. 1, 4 and 5 Preparation Plants for the cleaning of -48-mesh slurries. These large scale operations have been recently described by D. H. Davis. 1 C. P. Proctor and C. B. Carlson2 in their chapter on Froth Flotation of Coal in the AIME Seeley W. Mudd series book on Coal Preparation describe some of the practical applications of our Pittsburgh Coal Co. laboratory work in actual plant practice as well as summarizing part of the investigational work. The author presents this paper, however, as a supplement to their reports, and records the basic research accomplished in the laboratory investigational work as well as the results of experi¬ments using bulk oil flotation. In presenting this work the author wishes to state much more work must be done in applying the principles of flotation to cleaning coal, especially in view of recent studies and practices in other mineral beneficiation fields. METHODS OF CONDUCTING LABORATORY TESTS The bulk of the research work was conducted in the laboratory of the Champion No. r Preparation Plant. This plant has elaborate facilities for sampling and analyzing coal and proved to be an admirable location

Jan 1, 1948

By C. O. Fairchild

THE meaning of temperature control can be extended to cover not only the control of temperatures' but also the control of processes through a knowledge of the temperatures involved. In this sense it has a very wide interest. A list of the industries in which temperature control is used in one way or another would cover nearly the entire industrial field. This discussion will be confined to the field of high temperatures. In practically all industries involving operations at high temperatures, pyrometers are used or men are paid for their ability either to estimate temperatures or gage an operation by some physical or chemical change or condition dependent on temperatures. As progress is made in the development of instruments and of methods for measuring temperature, some of these highly skilled artisans are learning the use of a new tool. Many processes have been, in recent years, improved by means of exact measurement thus substituted for estimation, but in a great many industries the pyrometer has had practically no opportunity to demonstrate its usefulness. The perfecting of instruments must be accompanied with a dissemination of the knowledge that new instruments are available and can be economically used. The demand at present, however, is ahead of the supply, and many industries are handicapped by the want of pyrometers. One of the highest paid skilled tradesmen of the present time is the man in the steel rolling mill who knows when proper working temperatures are attained. The metallurgist in his development of steels is continually demanding closer adherence to given temperature ranges in the processes, and the pyrometer is rapidly becoming indispensable. Properties of the finished products are being correlated with working temperatures and so closely that in some cases even the pyrometer is taxed to give the required accuracy. The greatest progress has been made in those industries in which the lower temperatures are used, particularly below 500° C. In this lower range automatic control has been highly developed.

Jan 9, 1919

By B. C. Allen

The interface energies of chronzium, molybdenunz. hugsten, and their solid-solution alloys Cv-35Re, MO-33Re, and UJ-25Re were studied at 0.6 to 1.0 of the absolllte liquidus ter)zpe,vature using fiz&apos;e )izethods. Liquid surface tension, yv , was deter mined clsing the pendant-drop and drop-weight methods. Results are, respectizlely, 1700, 2370, and 2480 +100 dynes per ct for the rhernium -containing alloys and essentially the same as tlwse reported for liquid chro)riln, trolybdenum, and tungsten. Average solid slrjace energy, rsv< xias ))zeasured using tlre fiber-extetlsion method. The ratio of ysS, the acerage high-angle grain-boundary energy, to ySV cclas jolnd fronz grain-bolzdary grooue angles fort)zed at the surface in an inert atrfizosphere. Absolllte iute?:face energies were deterawined using ?nultip/rase equilibria involzing suitable liquids of known surface tension (tin, silver). Interpretation of the experimented results in view of pvobable tenzperatzcre, orientation, and purity effects giz,e the follouling approximations in ergs per sq ctn: ysv (i2lo. Mo-33Re) - 2100, ySS (Mo, Mo-33Re) - 800, rr (defornzation twins in MO-33Re at 1200"C) - 800. ysV (Cr. Cr-35Re) - 2400. YSS (CY, Cr-35Re) - 1000. Probably Ylv- YSV- 2500 for tungsten and W-25Re, giving yss (It&apos;, W-25Re) - 900. The interface energies of solid and liqid ch?&apos;omiu?.z, nolybdenu?rr, and tungsten are not geatly aff&apos;ected by rhenium and therefore are not a ttlajor factor in the ductili zing rhenium effect in Croup VI-A metals. THE interface energies of the refractory Group VI-A metals, chromium, molybdenum, and tungsten, are not well-established. The objective of this investigation was to study the liquid surface tension, solid surface energy, and grain-boundary energy of these metals and compare them to those found for the bcc solid-solution alloys, Cr-35e,&apos; 0-33e,&apos; and -25e. Five techniques were used to measure interface energies in high-purity polycrystal rod, wire, and sheet at 0.6 to 1.0 of the absolute liquidus temperature. The alloys were chosen to see if there was any connection between interface-energy behavior and the ductilizing rhenium effecL4j5 EXPERIMENTAL WORK Materials. A description of the materials used is presented in Table I. Chromium rod was prepared by arc melting iodide process crystals supplied by Chromallo Cor., hot extruding, and warm swaging to 0.63-cm-diam rod.6 The sheet was prepared by rolling as-extruded rod to 95 pct reduction in area from a hydrogen furnace at 800" to 900°C and surface grinding off 0.02 cm from each face. Cr-35Re rod was prepared by arc melting sintered rhenium powder and iodide chromium crystals, warm rod rolling to 50 pct reduction in area in cans, and swaging to 60 pct reduction in area at 1100" to 1200°C. Some of the rod was warm-rolled to sheet and then surface-ground. Portions of swaged chromium and Cr-35Re were further reduced by swaging and drawing to 0.013-cm-diam wire by the General Electric Co. Mo-33Re and W-25Re rod, sheet, and wire were provided by Chase Brass and Copper Co. The molybdenum sheet consisted of two lots, both essentially the same except for the carbon content. Liquid Surface Tension. The liquid surface tension of Cr-35Re, Mo-33Re, and W-25Re was measured by a combination of pendant-drop and drop-weight methods using techniques already decribed." Following out-gassing, molten drops were formed on the ends of centerless-ground Mo-33Re and W-25Re rods by electron bombardment at 5 x 106 mm. Similar drops were formed on outgassed Cr-35Re rods by induction heating under 1 atm of 99.995 pct Ar. Solid Surface Energy. Solid surface energy was measured by conducting microcreep experiments on molybdenum, Mo-33Re, chromium, and Cr-35Re wires at 2350°, 2306, 1550°, and 180O°C, respectively. In preparation, gage marks -2.5 cm apart and -0.001 cm deep were circumferentially scribed on the wire with a razor blade. Weights of the wire material were then attached. Five to seven reasonably straight wires were hung in a container made out of the wire material. The free end was placed through a small hole in the removable top and secured by bending a small portion 90 deg. The containers not only tended to provide vapor-solid equilibrium for the wires but also protected them from gaseous impurities. They were nominally 2.5 cm in diam by 5 cm high and were made from extruded chromium rod, Cr-35Re arc casting, molybdenum bar stock, or welded Mo-33Re sheet. After deg re as ing, the assembly was outgassed at a relatively low temperature to 2 x 10"5 mm and then recrystallized 2 to 8 hr at the creep temperature in a rhenium-element resistance furnace. The static argon atmosphere was gettered by tantalum radiation shielding. Specimen temperature was measured optically to 25"C using calibration with known melting points and blackbody conditions. The wires generally developed a stable bamboo-type structure according to Fig, l(b), (c), and (d) and retained their gage marks [upper portion of Fig. l(d)]. One or two of the weights were clipped off to provide a low load for the creep anneal. To minimize the possibility of bending or breakage, the wires remained attached to the top of the annealing container which was held to keep the wires vertical. The distance between gage marks was

Jan 1, 1967

By W. W. Beddow

TWENTY years or so ago I wrote an article on management which consisted mostly of a chart similar to thousands of others of that day showing line functions, staff functions, and the chain of command in a typical mining organization. Since hen we have been "bossing" from the faces to the swivel chair and we have made many errors of no little expense to our companies. We have kept the chart in mind but many times we have changed the functions to fit the people we have had to work with. Good management after all is getting results with the people, the equipment, the supplies, and the natural conditions of the coal seam or seams and adjacent strata present. We have made, with little effort, a good showing with average people and equipment in good natural conditions. We have made a miserable showing (although expending every personal effort) with better than aver- age people and equipment in bad natural conditions. In the latter case many of our stockholders felt that better management would have found some way to save their investment. Perhaps they were right.

Jan 1, 1944

By A. S. Richardson

AIR conditioning, or air cooling, for the improvement of ventilation in the Butte mines has come into increasing use during the past 10 years. In part, the methods practiced have been described in previous publications of the Institute, but some improvements on earlier methods have been made and a number of new features have been developed. This paper is presented as a record of progress made, and for the sake of completeness describes all general features of the work. The need for air conditioning in the ventilation of mines in the district arises from the fact that the temperature of the ground and mine water has shown a very great increase with increase in mining depth, and has now reached a maximum of slightly over 130ºF. The most difficult part of the ventilation problem is the maintenance of temperature and humidity of a satisfactory standard in the working places, especially on the lower levels. Although ordinary ventilation is adequate to maintain good conditions in most of the working places it is subject to a number of limitations at great depth. Most important among these limitations is that with increase in depth the air becomes heated before it reaches the working places, both by compression from increase in atmospheric pressure and by heat transferred to it from rock at high temperature, so that its capacity for lowering temperatures is greatly reduced before it reaches the operating zone. Increasing depth of mining also increases the distance traveled by the air in its passage through the mine, and this causes a corresponding increase in resistance to air flow, so that there is greater difficulty in maintaining even the same volume in circulation. Thus, in the face of a demand that the ventilating system have a very much greater capacity to remove heat from the mine, the tendency is for that capacity to diminish. The only evident alternatives were (I) the opening of additional air shafts to increase the volume of air in circulation, (2) an extension of the existing system that would be subject to the same limitations, or (3) the adoption of an entirely different method such as air cooling. Fortunately for an economic solution of the problem, the mean annual temperature of the surface atmosphere at Butte is about 40°F., with very low relative humidity in summer, so that there is unlimited natural cooling power at a temperature range adaptable to air-conditioning methods. METHODS Two similar methods of air conditioning are used, as necessitated by service requirements and dependent upon the equipment available. In one, which is the more important and has the greater cooling capacity, water is circulated in a closed circuit, and, alternately, first absorbs heat from warm mine air and then dissipates it in the surface atmosphere by cooling at a cooling tower. The second

Jan 1, 1941