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By Michael Chender

The current outlook for financing new copper production is not very encouraging. At a time when companies are slogging through a protracted period of low prices as well as having to accept lower profits due to more stringent tax and royalty schedules, banks are beginning to require companies to take a greater equity interest in new projects. Mineral resource financing, including copper, seems to have lost much of its appeal to the lending institutions, and loans of any kind to many of the developing countries -from which over half of new copper capacity could be expected to come-are being examined much more critically than they were in the late 1960's and early 1970's.

Jan 12, 1976

By G. S. Ansell, J. Weertman

The creep behavior of an aluminum alloy hardened with a finely dispersed phase of aluminum oxide was investigated. The as-extruded alloy shows an approximate steady-state creep in which the creed rate depends exponentially on the applied stress. The activation energy of creeb is abbroximately 150,000 cal per mole. The recrystallized alloy shows no steady-state creep. ONE method of improving the creep resistance of a metal is to introduce a finely dispersed second phase into the metal matrix. The improvement of the creep resistance has been qualitatively explained by assuming that the dispersed second-phase particles act as obstacles to dislocation motion. If the main effect of second-phase particles is simply to hinder dislocation motion then it is possible to derive a high-temperature creep equation for a dispersion-hardened alloy in a straightforward manner. In the Appendix of this paper such an equation is derived from a creep model which works very well for pure metals. Recently, F. V. Lenel has fabricated, for the first time, powder extrusions of aluminum-aluminum oxide in a large-grained recrystallized form. This alloy, designated as MD 2100, consists of a fine dispersion of aluminum oxide plates in a matrix of commercial purity aluminum. A considerable amount of investigation has been carried out concerning the microstructure and physical properties of this alloy.&apos; ) The aluminum oxide is present in the form of flakes 130A units thick and 0.3 u on edge. They are dispersed in the aluminum matrix with an average spacing of approximately 0.5 jx. The spacing varies in the range of 0.05 to 1.5 µ. The alloy structure is extremely stable at high temperatures. For this reason the alloy offers a unique opportunity for a fundamental study of creep of a very finely dispersed two-phase alloy. Lenel supplied specimens in both the unrecrystallized and recrystallized condition. This paper reports high-temperature creep experiments carried out on these specimens. The results obtained were rather unexpected. No steady-state creep was observed in the recrys-tallized material. In fact, after some transient creep which takes place upon loading, the creep rate is essentially zero ( < 10-8per min). If the second-phase particles acted solely as obstacles to the motion of dislocations, measurable steady-state creep would be expected. Since none is observed it appears that the main effect of the fine dispersion in the recrystallized material is to inactivate the dislocation sources themselves, rather than hinder the motion of dislocation loops created at these sources. EXPERIMENTAL DETAILS Specimens were tested in wire form, 0.087 in. in diam for the as-extruded alloy, and 0.035 in. in diam for the recrystallized alloy. These samples were held in friction-type wire grips; a gage length of 2.5 cm was used for all the creep tests. The specimens were held at 600°C in the test apparatus for at least 15 hr prior to each test. The tests were run under the condition of constant loading and, since the creep strains were small, can be considered as constant stress tests. The temperature of testing was held constant within 3°C. Elongations were measured with an optical cathetometer which was capable of measuring strains as smaIl as 0.00012. This allowed the measurement of strain rates as low as l0-8&apos;per rnin. In addition to the creep tests optical micrographs were made in order to determine both the grain size and microstructure of these materials. RESULTS Fig. 1 shows a few typical creep curves obtained from the as-extruded material. The elongations were somewhat erratic, but each curve shows a region of quasi-steady-state creep from which an approximate steady-state creep rate can be obtained. In general the higher the stress at a given temperature, the greater the total elongation before fracture. The lower the applied stress, the longer is the region where the creep rate is almost constant. Summary data from the creep tests of the as-extruded material are listed in Table I. The steady-state creep data of the as-extruded material for a range of stresses at a constant temperature follow a creep equation of the type creep rate = K&apos; = A exp (&) [11 where A and B are constants, k is Boltzmann&apos;s constant, T is the absolute temperature, and a the stress. The standard error of estimate of the data received is less than one order of magnitude. As shown in Fig. 2, if one compensates the creep-rate data for the effect of temperature over the range of test temperature, the steady-state creep data roughly follow a creep equation of the type Temperature compensated creep rate = K* = A exp

Jan 1, 1960

By WILLARD HAYES

(Glen Summit Meeting, June, 1911.) THE determination of the question whether the Mayari and Moa mining-claims of the Spanish-American Iron Co. have been rightly denounced under the third section of the law of bases rests on the findings in the following questions of fact: 1. Is the mineral an iron-ore? 2. Is the iron-ore a bog iron-ore? 3. Is the iron-ore ocher? 4. If ocher is present, can it be mined separately and independently of the iron-ore ? 1. IS THE MINERAL AN IRON-ORE? Since the material is shown by a large number of analyses to contain from 41. to 50 per cent. of metallic iron and less than 0.02 per cent. of phosphorus, and since it has been and is being actually used on a commercial scale for the production of iron and steel, it must be classed as an iron-ore. 2. IS THE IRON-ORE A BOG IRON-ORE? Bog iron-ore has certain invariable characteristics of chemical composition, physical appearance, geological relations, and origin by which it can always be recognized with certainty. In chemical composition, it is the hydrated sesquioxide of iron, limonite, or a mixture of limonite and other closely-related iron hydrates. It never contains the anhydrous oxides-hematite or magnetite; is never magnetic, and never contains either nickel, chromium, or cobalt oxides. On the other hand, it is invariably high in phosphorus-content. In physical appearance and texture it is a yellow or reddish-brown amorphous spongy material, and always contains water-worn sand-grains, silt, clay, and plant-remains. In its geological relations it is wholly independent of the rock

Mar 1, 1911

By N. R. Morrow, C. C. Harris

The experimental points which describe capillary pressure curves are determined at apparent equilibria which are observed after bydrodynamic flow has ceased. For most systems, the time required to obtain equalization of pressure throughout the discontinuous part of a phase is prohibitive. To permit experimental points to be described as equilibria, a model of capillary behavior is proposed where mass transfer is restricted to bulk fluid flow. Model capillary pressure curves follow if the path described by such points is independent of the rate at which the saturation was changed to attain a capillary pressure point. Aemodified suction potential technique is used to study cyclic relationships between capillary pressure and moisture content for a porous mass. The time taken to complete an experiment was greatly reduced by using small samples. INTRODUCTION Capillary retention of liquid by porous materials has been investigated in the fields of hydrology,l soil science,2 oil reservoir engineering,3 chemical engineering," soil mechanics,5 textiles: paper making: and building materials In studies of the immiscible displacement of one fluid by another within a porous bed, drainage columnsl and suction potential techniques2 have been used to obtain relationships between pressure deficiency and saturation (Fig. 1). Except where there is no hysteresis of contact angle and the solid is of simple geometry, such as a tube of uniform cross section, there is hysteresis in the relationship between capillary pressure and saturation.2 The relationship which has received most attention is displacement of fluid from an initially saturated bed (Fig. 1, Curve R2), the final condition being an irreducible minimum fluid saturation Swr. Imbibition (Fig. 1, Curve A), further desaturation (Fig. 1, Curve R), and intermediate scanning curves have been studied to a lesser but increasing extent.2 ,3,9-12 This paper first considers the nature of the experimental points tracing the capillary pressure curves with respect to the modes and rates of mass transfer which are operative during the course of measurement. There are clear indications that the experimental points which describe these curves are obtained at apparent equilibria which are observed when viscous fluid flow has ceased; and any further changes in the fluid distribution are the result of much slower mass transfer processes, such as diffusion. Unless stated otherwise, this discussion applies to a stable packing of equal, smooth, hydrophilic spheres supported by a suction plate5 with water as the wetting phase and air as the nonwetting phase. The discussion can also be applied, in many

Jan 1, 1966

By P. Sanchez-Mejorada

GEOLOGISTS who are acquainted with the mines of northeastern Mexico realize that the most important lead-silver replacement deposits of the province are confined to a single formation. But since the formation is several hundred meters thick, the author has determined the relative position of the lead mantos in the belief that this information will prove useful in the search for new mines. This article describes the stratigraphic location of lead-silver replacement deposits known in several mines situated in a region comprising part of the states of Coahuila and Nuevo Leon. The area studied extends for 200 km* (125 miles) from east to west and 70 km (45 miles) north to south. Metallogenic Province: The most important metallic deposits of the region have the following common characteristics: 1) The orebodies occur as manto replacements of calcareous sediments. 2) The horizons that have contributed large tonnages of ore are in similar positions in the corresponding stratigraphic columns (as it will be shown later on). 3) Lead is the most important metal in the ores. Silver is commonly present in small amounts. Occurrence of zinc is dependent on the degree of oxidation of the primary sulfides. 4) A large proportion of the total production has been in the form of oxidized ores. 5) The deposits are located on anticlines. Rocks of Cretaceous age crop out over large areas of the states of Nuevo Leon and Coahuila. forming part of a belt that extends to the south along the eastern Sierra Madre. The sediments are cut by a small number of intrusive stocks ranging in characteristics from rhyolite to diorite. The most prominent structural feature of the region is a series of folds trending northwest-southeast. Faulting is not conspicuous in the region, although a major fault zone is found farther East.&apos; The physiography closely reflects structural features, with mountains formed by anticlines and valleys conforming with intermediate synclines. Narrow valleys have also been developed along the axes of many anticlines, where solution of limy sedi- ments and erosion have proceeded along axial tension fractures. Stratigraphy: Rocks of the Upper Cretaceous are exposed in only a small percentage of the total area. Generally they have been eroded away from the mountains and are covered by recent talus and alluvium in the valleys. Humphrey&apos; has published an excellent paper describing the Cretaceous formations of the Sierra de los Muertos, a short distance west of Monterrey. A brief summary of these formations is given below to convey an overall picture of the stratigraphic sequence that prevails just south of the area under consideration. Upper Cretaceous Indidura: Essentially thin shaly sediments. Cuesta del Cura: Limestone in thin wavy beds

Jan 1, 1959

By Robert U. King, John W. Vanderwilt

THE Climax molybdenite deposit in Lake County 100 miles southwest of Denver is located in the central part of the mineral belt extending northeasterly across the state. Principal geographic features and geology are shown on Fig. 1. The first period of molybdenite mining, which began in 1918, ended in April 1919 because of limited demand and a price drop to about 72¢ per lb. During this time the ore came from the Leal level and surface outcrops at a higher elevation. Rate of mining was 250 tpd and several million tons of ore averaging 0.7 pct molybdenite were developed. Since April 1924, when the second period* began, Climax Molybdenum Co. has been the only operating company. Production in 1924 was 400 tpd and finding ore was a continual problem. When the White tunnel was extended, however, further ore was encountered. The orebody was thought to be tabular until 1926, when B. S. Butler recognized the relation of the developed ore on the Leal and White levels to a central area of fine-grained hydrother-mal quartz, and by 1929 diamond drilling had blocked out indicated ore reserves in excess of 100 million tons. In 1946, on the basis of information obtained from 25 miles of mine workings and a completed exploratory program involving over 200,000 ft of diamond drilling, the present authors reviewed and brought up to date the geology of the orebody. More recently Sears," employing microscopic techniques, made a study of hydrothermal alteration and mineralization, and Howell and Schassberger&apos;" restudied available geologic data. Production (1953) of molybdenite ore has been expanded to over 25,000 tpd and total production from 1918 through 1953 has been: Tungsten, tin, and pyrite are byproducts and monazite also was produced from 1949 through 1951, after which it was not saved. A maximum of 15 to 20 tons of monazite was produced. Geology of the Area Pre-Cambrian crystalline rocks constitute most of the Mosquito Range for several miles to the north, east, and south of the Climax molybdenite deposit, see Fig. 1. To the west the crystalline rocks are in fault contact with shales and sandstones of Pennsyl-vanian age. Both crystalline rocks and sediments are intruded by dikes and sills of Tertiary age. Numerous faults with small displacements are to be found in the crystalline rocks east of the Mosquito fault and in the sedimentary beds to the west. Pre-Cambrian Rocks: The pre-Cambrian rocks consist of schist and gneiss, identified with the Idaho Springs formation, and granite with minor pegmatite correlated with the Silver Plume granite of the Silver Plume area. The Idaho Springs formation is a general term applied to pre-Cambrian schist and gneiss found over a large part of the Colorado Front Range. At Climax this formation consists largely of biotite-schist and quartz-biotite gneiss with minor quantities of plagioclase and orthoclase, although in places appreciable quantities of feldspar and quartz are present in the more gneissic varieties. Locally, especially along the contact with granite, recrystal-lization of the schist has produced coarser texture and a more pronounced than average gneissic appearance. The gneiss and schist have been mapped as a single unit by Butler and Vanderwilt (1933)" and by Singewald (1951).12 Schist predominates at the higher elevations of the Mosquito Range and in the area to the north and east of Climax. The regional trend of schistosity is northeast with varying dips to the east. Silver Plume granite and associated pegmatite intrudes the Idaho Springs formation. Silver Plume granite in many places and in the Climax district in particular has an irregular form, and many large and small inclusions of schist and gneiss occur within the granite. Granite predominates at the surface in the immediate vicinity of the area of hydrothermal alteration and extends for several miles to the northeast and southeast. As more schist is present at lower levels of the mine than in the upper levels, the suggestion is that the granite is sill-like in form,

Jan 1, 1956

By H. H. Kellogg

Available high-fernperatzwe equilibrium measurements and other thermochernical data have been critically reciewed for sulfation reactions of the type: Recommended values for log K and ?Fo as junctions of temperature are given for thirty-six suck reactions involving twenty-six different metals. Methods of calculation and choice between conflict-ing data are discussed. SELECTIVE sulfation now enjoys a considerable renaissance as a metallurgical unit process due, in large part, to the available of the fluid-bed re- actor—a device capable of the close control of temperature and gas composition necessary for a successful sulfation process. An additional need, however, if sulfation chemistry is to be approached in a scientific manner, is a reliable body of data on the equilibrium and kinetics of sulfation reactions in simple and complex systems. This paper offers a critical review and compilation of equilibrium data on pure sulfates (simple systems). The last such review, by K. K. Kelley in 1935:30 has proven itself most useful, but the existence of many new data makes necessary a re-evaluation of the available information. METHODS OF CALCULATION For a simple sulfation reaction such as MS04(c) = MO(c) + SO3 [1] there are two approaches one may take toward establishing the value of ?Fo or K as a function of

Jan 1, 1964

By John E. Lanning

During the last decade, since most smelters have included Cottrell plants as standard equipment for the removal of dust from furnace gases, it has become apparent that smeltermen have had a new problem slowly developing. This problem has manifested itself in accelerated destruction of, or serious injury to, the masonry of flues and chimneys. The masonry either spalls, if the material is of low strength, or acquires large major cracks, either of which conditions attains such proportions that renewals or reinforcing become necessary to maintain the structure in satisfactory condition. This paper describes the failure of a large modern brick chimney to such an extent that its safety was vitally impaired; the investigation of its condition; the methods of restoring satisfactory strength to the structure; and the installation of an acidproof lining. Plant History The Clarkdale smelter of the United Verde Copper Co., which was put in operation in 1915, was primarily a blast-furnace plant. The smelter at Jerome had utilized blast furnaces exclusively, and in the design of the new (1915) plant, blast-furnace smelting evidently was considered of major importance, the smelting equipment consisting of four blast furnaces 48 in. by 26 ft. 8 in. and three reverberatories, each 19 by 101 ft. The latter, supplemented by roasters, were intended mainly for handling dust and fine ore resulting from the crushing operations. The original roasting equipment consisted of six six-hearth Wedge roasters, six more being added in 1917. All gases from blast furnaces, reverberatories, roasters and converters were conducted by means of suitable flues and dust chambers to one central chimney. This chimney, 30 ft. inside diameter by 400 ft. high, is a self-supporting steel structure, lined with 4-in. brick supported on steel shelf angles, riveted to the shell, spaced about 15 ft. vertically. The bricks were of local manufacture, not particularly hard-burned, and were laid in ordinary cement-fireclay-sand mortar. No record is available to indicate that any particular effort was made to secure an acidproof mortar. The same materials were employed in the construction of the reverberatory and roaster flues, and the roaster dust chamber. Parenthetically, it may

Jan 1, 1934

By Y. Oka, H. Majima

When a rock particle is subjected to an external force, internal stresses and deformations are experienced by the particle. Assuming that the breakage of a rock is mainly due to tensile stresses generated by the action of a pair of concentrated loads, F, directed in compression towards the loading points at the shortest distance, as illustrated in Fig. 1, the stress and deformation experienced by a particle of irregular shape can be determined with the aid of the theory of elasticity. According to the photoelastic experiments made by one of the present authors,&apos; the stress states in a rock particle of irregular shape are quite similar to that of an inscribed sphere of diameter x, as indicated in Fig. 1, but accompanied by the faint stresses, in the vicinity of the particle outside of the inscribed sphere. Therefore, the stress components in an irregularly shaped particle can be estimated by referring to stress components in a sphere. Applying polar spherical coordinates to an elastic spherical body, as shown in Fig. 1, the stress components are all expressed as multiples of F /x2 and more or less influenced by the loading angle and Poisson&apos;s number m. In general, the energy w, acting on a rock particle is defined as the product of loading compression F

Jan 1, 1970

By David White

THE submission of carefully prepared estimates of the oil reserves of the United States calls for no apology or explanation. In this country, petroleum is a rapidly wasting asset and an occasional appraisal of the amount remaining in the ground is a simple business procedure to safe-guard the general welfare and the prosperity of the republic. The rumored danger of failure, in the near future, of the foreign supply on which we depend in constantly increasing amounts makes the immediate review of our available reserves the more imperative. The Director of the U. S. Geological Survey, in March, 1921, requested the American Association of Petroleum Geologists to cooperate in the preparation of new estimates of the oil remaining in the ground. With the members of this cooperative committee, state geologists, regional geologists, consulting specialists, and geologists and engineers attached to many companies worked both independently and through sub-committees. The reports for districts, counties, fields, etc., after review by local or state committees, were discussed by the joint cooperative committee in conferences that, in some instances, were attended by the original compilers of estimates for the states or smaller areas. Finally the data were reviewed and the figures revised by the joint cooperative committee, so that the totals given in Table 1 represent the opinion of the committee, which was composed of F. W. DeWolf, W. E. Wrather, Roswell H. Johnson, Wallace A. Pratt, Alexander W. McCoy, Carl H. Beal, C. T. Lupton, G. C. Matson, K. C. Heald, W. T. Thom, Jr., A. E. Fath, Kirtley F. Mather, R. C. Moore, and David White, chairman.

Jan 6, 1922

By C. D. Woodward

The Anaconda Copper Mining Co. purchases 25,000 kw. of electric power for its mining operations at Butte, Mont. This power is delivered, over duplicate feeders, in the form of 60-cycle, 2400-volt, three-phase current, to five compressor plants, where most of the energy is used for driving air compressors. At the compressor plants are located the switching apparatus for controlling the 2400-volt power and distributing it to the various mines. At these points, also, there are a number of motor-generator sets for converting the alternating current to 275-volt direct current for the haulage systems. Pole lines convey the powcr from the compressor plants to outdoor transformer substations at most of the mines. When it is not economical to distribute the power at the lower voltages in the mines, transformers and motor-generator sets are placed at strategic points underground. All power is purchased on a maximum-demand basis; therefore there is installed at one of the compressor plants an eight-element totalizing graphic wattmeter. This instrument records simultaneously the value of all power taken at the numerous points of delivery, which not only climinates the diversity factor but permits load dispatching between compressor and pumping plants, and thus materially reduces the maximum demand from the power system. As most of the mine hoisting is done by 90-lb. compressed-air winding engines, the air-compressor equipment for the winding engines and mining operations is quite extensive. The standard air compressor has a rating of 7500 cu. ft. per min. of free air, and most of the compressors are directly connected to synchronous motors. The synchronous motors are designed for 80 per cent. loading power factor, thus facilitating power-factor correction of total mine load. Consequently by cooperation with the power company, the voltage of the power received at the compressor plants is constant. In the mines there are installed an induction motor load of approxi-mately 10,000 hp., and 4500 kv.-a,, in transformer capacity. It is the practice to install 2200-volt motors in the mincs, except those rated below 50 hp, hence there are in operation underground about 5000 hp., in the

Jan 1, 1923

By C. D. Woodward

The Anaconda Copper Mining Co. purchases 25,000 kw. of electric power for its mining operations at Butte, Mont. This power is delivered, over duplicate feeders, in the form of 60-cycle, 2400-volt, three-phase current, to five compressor plants, where most of the energy is used for driving air compressors. At the compressor plants are located the switching apparatus for controlling the 2400-volt power and distributing it to the various mines. At these points, also, there are a number of motor-generator sets for converting the alternating current to 275-volt direct current for the haulage systems. Pole lines convey the powcr from the compressor plants to outdoor transformer substations at most of the mines. When it is not economical to distribute the power at the lower voltages in the mines, transformers and motor-generator sets are placed at strategic points underground. All power is purchased on a maximum-demand basis; therefore there is installed at one of the compressor plants an eight-element totalizing graphic wattmeter. This instrument records simultaneously the value of all power taken at the numerous points of delivery, which not only climinates the diversity factor but permits load dispatching between compressor and pumping plants, and thus materially reduces the maximum demand from the power system. As most of the mine hoisting is done by 90-lb. compressed-air winding engines, the air-compressor equipment for the winding engines and mining operations is quite extensive. The standard air compressor has a rating of 7500 cu. ft. per min. of free air, and most of the compressors are directly connected to synchronous motors. The synchronous motors are designed for 80 per cent. loading power factor, thus facilitating power-factor correction of total mine load. Consequently by cooperation with the power company, the voltage of the power received at the compressor plants is constant. In the mines there are installed an induction motor load of approxi-mately 10,000 hp., and 4500 kv.-a,, in transformer capacity. It is the practice to install 2200-volt motors in the mincs, except those rated below 50 hp, hence there are in operation underground about 5000 hp., in the

Jan 1, 1923

By Charles R. Keyes

Discussion of the paper of Charles R. Keyes, Bi-Monthly Bulletin, No. 19, January, 1908, pp. 1 to 31. BERNARD MACDONALD, Guanajuato, Mexico (communication to the Secretary*) :-Mr. Keyes&apos;s paper is very interesting to me because of my personal experience with the development of the ore-deposits of Lake Valley. Seeing that many of the important facts connected with the early history of the development of these mines are either now unknown, or have become more or less distorted, and thinking that it would be interesting as well as valuable to have these recorded as a historical supplement to Mr. Keyes&apos;s elaborate paper, I present the following narrative: In February, 1881, soon after the Atchison, Topeka & Santa Fé railroad made connection with the Southern Pacific at Denting, N. M., the Lake Valley properties were brought to the attention of New York and Philadelphia capitalists by John A. Miller, of Silver City, N. M. At that time silver was $1.10 all ounce and silver-mining was very attractive. Vast fortunes were being made in Leadville and other Colorado camps, and Tombstone was pouring out its millions. Lake Valley, like all&apos; other mining-camps in their early history, had its drawbacks, but the railroad, then passing within 14 miles of it, mitigated many of these. The camp lay in the foot-hills of the Black range, in which the Apaches had their stronghold, and raided, when it suited their convenience, the surrounding country, killing the prospectors and pioneer settlers and stealing their cattle. This band of Indians was joined by the outlaws and desperadoes from the frontiers of Texas, Arizona, and Mexico, who collectively defied the United States soldiers, restrained, as the latter were, by the mollycoddles from the East. The brutality of the Indian raids through Arizona and New Mexico in those days would scarcely be believed now, but they stain in deep

Feb 1, 1909

By James E. York

AT a meeting of the American Society for Testing Materials at Atlantic City, June, 1908, Dr.. C. B. Dudley, in his presidential address,&apos; showed the vital necessity of not only making a steel rail as good as in the past, but of making it considerably better in order to meet the present and prospective require¬ments of railroads. Doctor Dudley requested the co-operation of all who from personal experience could give information that would result in bringing about the production of a steel rail that could be relied upon to meet the present requirements. I have had considerable experience in the practical manufacture of steel of almost every grade, during the past 40 years, and I shall suggest changes that will bring about the results desired. Doctor Dudley has had a long experience as chemical and metallurgical expert for the Pennsylvania railroad, but he frankly admits that up to the present time both he and other metallurgical experts lack the practical knowledge of steel-making that is necessary to state correctly the reasons for the unreliability of the steel rails now produced. The necessity is self-evident for more positive practical knowledge on the part of these experts of what is possible and what is impossible regarding the practical manufacturing of steel rails from the ingot to the, finished product. Chemical knowledge in steel-making is far in advance of what it was years ago, and might be said to cover every requirement (in that department) for producing reliable steel. The study of the metallography of steel has been of great value, also the physical testing of steel, but this knowledge will only de-

May 1, 1909

By William P. Shinn

It is almost exactly seven years since the last previous meeting of the Institute in this city. In a paper on " Pittsburgh, its Resources and Sorroundings," read at that meeting, I showed that Allegheny County had produced in 1878, " one-twelfth of all the pig-iron,.... two-ninths of all the rolled iron (except rails), over one-eighth of all the Bessemer and open-hearth steel, two-thirds of all the crucible blister and puddled steel, one-fourth of all the glass, one-eighth of all the coal, and one-sixth of all the pig-lead produced in the United States;" and the object of this paper is to show that, great as the record then was, it has been greatly surpassed since.* Population. In my former paper I expressed the opinion that the census of 1880 would show the population of Allegheny County to be in excess of 300,000. The census report made it 355,869. The following shows the growth of the county in population from 1790 to 1880: 1790,...........10,309 1800,........... 15,087 1810,...........25,317 1820,...........34,921 1830,...........50,552 1840.............81,235 1850............138,290 1860............178,881 1870,...........262,204 1880,...........355,869 This makes Allegheny County, in 1880, rank sixth in population of the counties of the United States, whereas in 1870 its rank was ninth. The population of Pittsburgh in 1880 was 156,359, being twelfth

Jan 1, 1886

By Charles C. Russell

Pressures developed by the coal during the coking process have been responsible for serious trouble to many companies that operate or build by-product coke ovens. The insidious nature of this trouble is indicated by the fact that oven operators, unless they have ascertained the characteristics of the coals they use, cannot determine the existence of dangerous pressures until after the damage has been done. A rather popular misconception is that ease of pushing of the charge at the completion of the coking period indicates that no dangerous pressure has been developed, but this is far from the truth; pressures developed during the coking period are often completely dissipated by the shrinkage of the charge in the completion of coking, and so any criterion based on the ease of pushing is futile. However, methods of testing coals are available that will definitely distinguish the dangerous coals from those that are safe, and such methods have been brought to a high degree of certainty. The operator should take no risk that involves either a lack of knowledge of the behavior of coals during coking or the failure to believe that certain of the coals or coal mixtures can cause damage to the oven structure. This merely tends to minimize the problem and leads to claims that coking coals of all kinds may be carbonized with no danger of damage to the oven structure provided some particular kind of byproduct oven is used. This lack of appreciation of the true situation is in itself one of the main factors leading to damage of coke-oven structures. Coals that develop more than a certain safe pressure cannot be used in by-product coke ovens without causing damage to the side flue walls. The following paper presents a highly certain method for the measurement of the pressures developed during the carbonization of coal—a method that is the culmination of many years of work on the problem in which a number of methods for the purpose were investigated and used. While actual pressures found may appear to be small when expressed in pounds per square inch, the number of square inches in each oven wall is so large that the total pressure on the oven wall becomes an enormous load.

Jan 1, 1940

By Charles C. Russell

Pressures developed by the coal during the coking process have been responsible for serious trouble to many companies that operate or build by-product coke ovens. The insidious nature of this trouble is indicated by the fact that oven operators, unless they have ascertained the characteristics of the coals they use, cannot determine the existence of dangerous pressures until after the damage has been done. A rather popular misconception is that ease of pushing of the charge at the completion of the coking period indicates that no dangerous pressure has been developed, but this is far from the truth; pressures developed during the coking period are often completely dissipated by the shrinkage of the charge in the completion of coking, and so any criterion based on the ease of pushing is futile. However, methods of testing coals are available that will definitely distinguish the dangerous coals from those that are safe, and such methods have been brought to a high degree of certainty. The operator should take no risk that involves either a lack of knowledge of the behavior of coals during coking or the failure to believe that certain of the coals or coal mixtures can cause damage to the oven structure. This merely tends to minimize the problem and leads to claims that coking coals of all kinds may be carbonized with no danger of damage to the oven structure provided some particular kind of byproduct oven is used. This lack of appreciation of the true situation is in itself one of the main factors leading to damage of coke-oven structures. Coals that develop more than a certain safe pressure cannot be used in by-product coke ovens without causing damage to the side flue walls. The following paper presents a highly certain method for the measurement of the pressures developed during the carbonization of coal—a method that is the culmination of many years of work on the problem in which a number of methods for the purpose were investigated and used. While actual pressures found may appear to be small when expressed in pounds per square inch, the number of square inches in each oven wall is so large that the total pressure on the oven wall becomes an enormous load.

Jan 1, 1940

By JOSEPH MACDONALD

STRIPPED of its romantic possibilities, mining is a commercial business, carried on for the profit there is in it, and the business of the manager, in its ultimate analysis, is to make the profit as large as possible. The general manager of a mining company should keep himself personally familiar with all the details of its operations. If be fails to do so, chaos results, labor becomes inefficient, costs go up, and profits go down. Nowhere is this emphasized more than in Mexico. If the mining operations are extensive and complex, involving, besides the work of mining the ore, its transportation and treatment by various milling operations, and the marketing of the products, the business, to be carried on properly, must be divided into a number of main departments, which are subdivided into minor departments. Each main department should be under the immediate charge of a superintendent, or a foreman, and each minor department under a shift-boss. Organized in this way, and with all the principal centers of activity connected by telephone, the manager can keep in touch at all times with the details of every branch of the business, and be in a position to perform effectively the full duty of manager. The ?total cost of mining operations may be broadly divided under the heads of Labor, Supplies, and Marketing. Of these, it will be found, on averaging a number of cases, that the cost of labor will be about two-thirds of the total cost. The importance, therefore, of an efficient labor-department will be apparent. This department must be sub-divided and organized differently, according to the peculiar conditions at each mine, and no one system, however well suited for one particu-

Jan 1, 1909

By Fredrick C. Pearson, Albert Brown, Emil R. Ermert

EARLY in 1946 the Shen-Penn Production CO., a subsidiary of the Philadelphia and Reading Coal and Iron Co., was organized to operate the Shenan-doah Stripping, one of the largest open-pit anthracite mines in the world. This mine is located in the Western Middle Field near Shenandoah, Schuylkill County, Pa., and involves the removal of approximately 60,400,000 cu yd of overburden to permit the recovery of 9,200,000 gross tons of rough cleaned coal from an area 8000 ft long and 2700 ft wide, with a maximum depth of 400 ft. Operations began in August 1946, and within the next few years 31,811,-000 cu yd of overburden and 2,994,000 gross tons of rough cleaned coal had been removed. During the early days of open-pit mining operations, steam was the primary motive power. However, as the size of the equipment increased, so did the problems of fuel, water, labor, and maintenance. Because of its efficiency and convenience, electric power rapidly replaced steam. Later the modern diesel engine was developed, and today practically all stripping equipment is either electric, diesel-electric, or diesel-powered. In locations where electric power is not readily available or where operations are scattered over a large area, diesel power is favored. At Shenandoah operations are highly concentrated in a relatively small area, and this fact, coupled with the availability of ample electric energy, indicated the selection of electric-powered equipment. Since this was a new company, it was necessary to purchase every item, from the smallest tools to stripping shovels. Although the organization period was hampered by the postwar scarcity of materials, an excellent opportunity was afforded to set up a thoroughly modern plant. This paper will describe the power facilities, with particular emphasis on the more unusual features. The substation is a major item in a power distribution system, and a simple arrangement utilizing high quality equipment is an excellent investment. With this in mind, a 3000-kva unit type substation was selected and installed. This unit is made up of three sections, which are assembled simply by bolting together the various sections and connecting the power leads, see Fig. 1. The transformer proper, rated at 3000 kva, is oil-filled and nitrogen-sealed, having a 66,000-v Delta primary and 4160-v Wye secondary with a grounded neutral and 46-ohm ground resistor. The function of this resistor will be described later. Electrical energy is purchased from a public utility and is delivered to the main substation at 66,000 v over one or the other of two incoming lines. These lines terminate on a high voltage switching section on which high voltage fuses and Thyrite lightning arresters are installed. The outgoing feeder switching unit is made up of the following: 1—An auxiliary compartment consisting of potential and current transformers with necessary terminal blocks for connecting to power company metering equipment. 2—Another auxiliary compartment containing a control transformer, battery, and battery charger for the furnishing of power for tripping and reclosing of power circuit breakers. The assemblies in these auxiliary compartments are mounted on carriages that can be rolled in and out with ease. Potential transformers are readily accessible for inspection and fuse replacement. When withdrawn from the operating position they are completely de-energized and grounded. 3—Two feeder breaker compartments, each with a 1200-amp, 5000-v, solenoid-operated magneblast air circuit breaker, voltmeter, ammeter, overcurrent relays, and a ground relay. These power circuit breakers can be quickly and safely withdrawn or repaired. A built-in isolating mechanism is used for lowering the breaker to a transfer truck for repair or inspection or as a means of disconnecting the breaker from the source of power as an added precaution when working on power lines. Thus inspec-

Jan 1, 1953

By Albert Brown, Emil R. Ermert, Fredrick C. Pearson

EARLY in 1946 the Shen-Penn Production CO., a subsidiary of the Philadelphia and Reading Coal and Iron Co., was organized to operate the Shenan-doah Stripping, one of the largest open-pit anthracite mines in the world. This mine is located in the Western Middle Field near Shenandoah, Schuylkill County, Pa., and involves the removal of approximately 60,400,000 cu yd of overburden to permit the recovery of 9,200,000 gross tons of rough cleaned coal from an area 8000 ft long and 2700 ft wide, with a maximum depth of 400 ft. Operations began in August 1946, and within the next few years 31,811,-000 cu yd of overburden and 2,994,000 gross tons of rough cleaned coal had been removed. During the early days of open-pit mining operations, steam was the primary motive power. However, as the size of the equipment increased, so did the problems of fuel, water, labor, and maintenance. Because of its efficiency and convenience, electric power rapidly replaced steam. Later the modern diesel engine was developed, and today practically all stripping equipment is either electric, diesel-electric, or diesel-powered. In locations where electric power is not readily available or where operations are scattered over a large area, diesel power is favored. At Shenandoah operations are highly concentrated in a relatively small area, and this fact, coupled with the availability of ample electric energy, indicated the selection of electric-powered equipment. Since this was a new company, it was necessary to purchase every item, from the smallest tools to stripping shovels. Although the organization period was hampered by the postwar scarcity of materials, an excellent opportunity was afforded to set up a thoroughly modern plant. This paper will describe the power facilities, with particular emphasis on the more unusual features. The substation is a major item in a power distribution system, and a simple arrangement utilizing high quality equipment is an excellent investment. With this in mind, a 3000-kva unit type substation was selected and installed. This unit is made up of three sections, which are assembled simply by bolting together the various sections and connecting the power leads, see Fig. 1. The transformer proper, rated at 3000 kva, is oil-filled and nitrogen-sealed, having a 66,000-v Delta primary and 4160-v Wye secondary with a grounded neutral and 46-ohm ground resistor. The function of this resistor will be described later. Electrical energy is purchased from a public utility and is delivered to the main substation at 66,000 v over one or the other of two incoming lines. These lines terminate on a high voltage switching section on which high voltage fuses and Thyrite lightning arresters are installed. The outgoing feeder switching unit is made up of the following: 1—An auxiliary compartment consisting of potential and current transformers with necessary terminal blocks for connecting to power company metering equipment. 2—Another auxiliary compartment containing a control transformer, battery, and battery charger for the furnishing of power for tripping and reclosing of power circuit breakers. The assemblies in these auxiliary compartments are mounted on carriages that can be rolled in and out with ease. Potential transformers are readily accessible for inspection and fuse replacement. When withdrawn from the operating position they are completely de-energized and grounded. 3—Two feeder breaker compartments, each with a 1200-amp, 5000-v, solenoid-operated magneblast air circuit breaker, voltmeter, ammeter, overcurrent relays, and a ground relay. These power circuit breakers can be quickly and safely withdrawn or repaired. A built-in isolating mechanism is used for lowering the breaker to a transfer truck for repair or inspection or as a means of disconnecting the breaker from the source of power as an added precaution when working on power lines. Thus inspec-

Jan 1, 1953