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By J. Leland Myer

IN a precise study of Pennsylvania anthracites, the research on European. anthracites is of little value to us because of their different physical and chemical nature. Likewise, there can be little correlation with the physical properties of bituminous and lower rank coals. Although all high-rank coals are thought to have had a common origin, microscopic examination revealing essentially the same kinds of organisms in similar .states of preservation, the different physical properties apparently arise from the degree or kinds of metamorphism of these coals. Representative samples from the Pennsylvania deposits have been selected for analysis, together with graphitic anthracite, bituminous coal, and some of the common forms of carbon. A complete list, with descriptions, is shown in Table 1.

Jan 1, 1932

By R. L. Robinson, P. DeFrank, R. F. Hatfield

Production equal to or greater than open-hole completions is possible through perforated completions if the flow paths throughout the perforations are free of obstructions.' Previous investigations have indicated that, in some cases, maximum productivity is not obtained due to plugging of the perforations with debris from the wellbore fluid and/or debris from the perforating process. Control of wellbore fluid and proper well completion techniques are very important in the elimination of perforation plugging.' Selection of properly designed perforating equipment also is quite important for maximum well productivity. Studies made with the use of the perforation flow laboratory, in which perforating tests are run under simulated well conditions, have shown that perforation plugging occasionally occurs. Plugs in perforations result from various causes. One of the contributors to plugging that can be controlled by the perforating device is the slug or carrot resulting from jet perforating. This condition has undergone extensive study, and previous developments have resulted in a decrease in carrot size—but not in complete elimination. It was felt that, if a method of completely eliminating the carrot could be found (with charge performance equal or better than previously obtained), a significant contribution would have been made. Such a charge has been developed and is reviewed in this paper. THEORETICAL CONSIDERATIONS OF CARROT ELIMINATION There are several popular theories of how a shaped charge jet is formed."," One of these is the hydrodynamic theory, wherein the liner is treated as a fluid under the impact of the explosive forces. Another is the spalling theory, where the interaction of shock waves in the liner causes small particles to be torn from the inner surface of the liner and projected at high velocity toward a common focal line to form the jet. It is not unreasonable to assume that both of these theories may be partially correct. For purposes of our discussion, it is simpler to use the second theory. Generally speaking, when a plate of metal is attacked by an explosive shock pulse, the pulse is transmitted through the metal at high velocity, as shown in Fig. 1(A). Pressures at the shock front may be 6 X 10' psi or higher. This shock wave (a compression wave) upon striking a free surface, Fig. 1(B), is partially reflected back as a tension wave. The interaction of the tension wave with the decaying compression wave causes a stress concentration in the metal; when this stress becomes great enough, a failure occurs and a small particle flies off and is projected away from the metal surface, as shown in Fig. 1(C). A new free surface is then presented to the shocks; the process repeats itself until there is no longer enough energy to cause failure, leaving a portion of the metal relativcly untouched. See Fig. 1(D). To apply this theory to a perforating shaped charge, consider the flat plate to be folded into a somewhat conical shape, with a column of explosive placed in intimate contact with the cone (Fig. 2). An explosive initiator detonates the charge, creating a shock wave

By AIME AIME

L H. DUSCHAK gave an interesting talk at a recent meeting of the. San Francisco Section, based -011 experimental work with a variety of ores at the laborator of the Treadwell-Yukon Co., in Berkeley, Cal. He was of the opinion that the customary "cut and try" method of flotation testing was still in evidence and that the flotation process was more of an art than an exact science. Propounded theories have enabled investigators to' classify reagents as well as to suggest new ideas both in the metallic and nonmetallic fields, but the application of theory has riot as yet been able to solve many of the unknown factors in operation.

Jan 1, 1932

The Library of the above-named Societies is open from 9 A.M. to 10 P.M. on all week-days, except holidays, from September 1 to June 30, and from 9 A.M. to 6 P.M. during July and August. The Library contains about 55,000 volumes, including sets of technical periodicals and the publications of scientific and technical societies. Membebs of the Institute, with few exceptions, are forced to spend a portion of their time in localities isolated from sources of information. To these the Library can render valuable service through correspondence; letters requesting information will receive special attention. The Library is prepared to furnish references and copies of articles on mining and metallurgical subjects; to determine the existence of mining-maps, and to furnish general information as to the geology and mineral resources of all countries. All communications should be made as definite as possible so that the information received may be what is desired and not include collateral matter which may not be of interest. The time spent in searching for such collateral matter will be saved, and the information will be sent more promptly and in more usable shape. The members of the Institute can he of service to the Library by forwarding copies of mining-reports, maps privately issued, and. similar material, which will be classified, indexed, and made available to other members. Suggestions for additions to the Library, either by purchase or personal solicitation as gifts, will he welcomed. It is hoped that members while in the city will use the Library freely, and assurance is given that most careful service will be rendered to them.

Jan 4, 1914

By T. Prof. Egleston

IF we may characterize the aim of metallurgists twenty years ago by any one point towards which their efforts were especially directed, we should say it was the idea of adapting "waste products" to some useful purpose, while the energy of to-day seems rather to take the direction of so arranging processes as to have no " waste products." The iron-master of this decade no longer speaks of the waste gases

Jan 1, 1873

By Charles Pack

DIE castings may be defined as metal castings made by forcing molten metal, under pressure, into a metallic mold or die. It is necessary to keep this definition in mind to avoid confusing this process with other permanent-mold casting processes. The fundamental principles of the process have been known and practised many years. The simplest application is embodied in the modern linotype machine in which molten metal (usually tin-lead alloy) is forced under pressure into a metallic mold. The pressure is derived from a piston and cylinder immersed in the molten metal. Progress in the art of die casting may conveniently be divided into threee groups: Machine for imparting pressure to the metal, material for the die or mold, casting alloys. CASTING MACHINES The problem of delivering molten metal under pressure into a die is comparatively simple, when dealing with low-fusing-point alloys, as the alloys of lead and tin, but it is much more complicated when dealing with metals of higher fusing points, such as the alloys of zinc, aluminum, and copper. Although the art of die casting is comparatively new and, to a large extent, unknown, the records of the patent office are replete with patents on the subject. Fig. 1 shows the Underwood machine patented in 1902; this is probably one of the first machines designed for the production of commercial die castings. The relation of this machine to the linotype casting machine is clearly. apparent. A cylinder and piston are immersed in the molten metal, the application of power to this piston forcing the molten metal, under pressure, into the mold or die. The Doehler machine, Fig. 2, patented in 1907, is based on the same general principles. This machine is used to a large extent at the present time, throughout the United States, for the production of zinc, tin, and lead alloy die castings.

Jan 2, 1919

By E. H. Crabtree, T. C. King

THE ferrosilicon grinding unit at the Central Mill of the Eagle-Picher Mining & Smelting Co. near Picher, Okla., was completed in March 1947. The object of the plant was to grind pigs of ferrosilicon, having a size of approximately 1 ½ by 4 by 12 in. and an analysis of 85 pct Fe and 15 pct Si, to approximately 100 mesh by crushing and wet grinding in a ball-mill classifier circuit. The minus-loo mesh ferrosilicon had formerly been purchased, and was used as medium in the heavy media process for treatment of lead-zinc ores. From the standpoint of dollars and cents, the cost of minus-100 mesh ferrosilicon was roughly $40.00 per ton more than pigs of the corresponding alloy delivered to the mill. Estimated wet grinding costs were considerably below this figure. The possible saving in cost of make-up medium for the cone plant was particularly attractive since, at that time, the plant losses averaged over four tons of minus-100 mesh ferrosilicon per day. Aside from the probable saving on the grinding charge, the need for such a unit was twofold. First, periodic fluctuations in the differential between the top and bottom densities of the cone were thought to be detrimental to metallurgy. There was little doubt that an intermediate differential existed at which the heavy media separation was most efficient, representing a compromise between concentrate grade and tailing loss. Furthermore, if a finer, but considerably cleaner, medium could be obtained, there was the possibility that the differential could be decreased without increasing the viscosity, or conversely, the viscosity of the medium decreased without increasing the differential. Preliminary to experimental work aimed at pegging the cone differential and circulating medium viscosity at whatever values were found to be most efficient, it was essential to have control over both the non-magnetic content of the medium and the particle size of the contained ferrosilicon. The latter was possible by means of a grinding unit at the mill. Second, whereas the ferrosilicon alloys are made by a number of manufacturers, only two, to our knowledge, grind it in any quantity for use in heavy media plants. For all practical purposes, the Central Mill was limited to one source of supply, a particularly vulnerable position. In case the supply was cut off, it was thought that pigs of the 85 pct Fe, 15 pct Si alloy could be obtained elsewhere, providing means of grinding them was available. There was no published information available covering wet grinding of ferrosilicon. Dry grinding in batch mills and in continuous mills with air classification was being practiced, but the cost of grinding was excessive and the dust condition objectionable. It appeared that primary and secondary crushing was no particular problem, providing heavy duty equipment was used;

Jan 1, 1947

By J. E. Gosline

In any theory of a hydrodynamic nature dealing with the vertical flow of gas-liquid mixtures in pipes, the two factors that present the greatest difficulty are the relative motion between the phases and the energy loss resulting from turbulence work. The former has generally been referred to in the literature as "slippage" and the latter as "friction." A third factor of importance is the nature of admixture between liquid and gas for both the relative motion between the phases as well as the turbulence work are functions of the type of mixture. Although much work of a general nature has been performed on the vertical flow problem, there have been very few attempts made to study experimentally the factors involved in the phenomenon individually. Of these, perhaps the most notable is the work of Moore and Wilde1 on slippage. Some writers on the subject have assumed that over a wide range of operating conditions the controlling type of mixture is one in which gas bubbles of uniform size are distributed throughout the liquid, and that the data obtained from experiments on the motion of single bubbles through various liquids may be used in evaluating the slippage. Ver-sluys2 has further assumed another controlling type of mixture in which the liquid occurs as a dispersed phase within the gas and applies data on the fall of drops of water in air to calculating the relative velocity. It was for the purpose of studying the applicability of data on single bubble motion to the slippage factor and to further observe the nature of mixtures that a research program was conducted at the University of California during 1932 and 1933. These experiments formed a basis for

Jan 1, 1936

By J. E. Gosline

In any theory of a hydrodynamic nature dealing with the vertical flow of gas-liquid mixtures in pipes, the two factors that present the greatest difficulty are the relative motion between the phases and the energy loss resulting from turbulence work. The former has generally been referred to in the literature as "slippage" and the latter as "friction." A third factor of importance is the nature of admixture between liquid and gas for both the relative motion between the phases as well as the turbulence work are functions of the type of mixture. Although much work of a general nature has been performed on the vertical flow problem, there have been very few attempts made to study experimentally the factors involved in the phenomenon individually. Of these, perhaps the most notable is the work of Moore and Wilde1 on slippage. Some writers on the subject have assumed that over a wide range of operating conditions the controlling type of mixture is one in which gas bubbles of uniform size are distributed throughout the liquid, and that the data obtained from experiments on the motion of single bubbles through various liquids may be used in evaluating the slippage. Ver-sluys2 has further assumed another controlling type of mixture in which the liquid occurs as a dispersed phase within the gas and applies data on the fall of drops of water in air to calculating the relative velocity. It was for the purpose of studying the applicability of data on single bubble motion to the slippage factor and to further observe the nature of mixtures that a research program was conducted at the University of California during 1932 and 1933. These experiments formed a basis for

Jan 1, 1936

By A. S. Richardson

THE design of mine airways receives, in general, very little engineering treatment. To a large extent this is, of course, due to the fact that information upon which to base calculations is seldom available in definite form. In many mines the extent of the workable deposits may not be known at the time an air course is planned, and the length of service is indeterminable. Volume of air required for ventilation may also increase with extension of the life of a property, and natural obstacles, such as heavy ground, often place limitations upon the size of opening that can be maintained. Perhaps a majority of the shafts used in ventilation of metal mines were originally intended as hoisting shafts, and many of the tunnels and cross-cuts similarly used, were also designed as haulage ways or for other operating purposes. Even when a shaft is sunk solely for ventilation, custom usually dictates a size and shape consistent with the type commonly used for ordinary operations, because experience has demonstrated it can be excavated and maintained. In fact it may not be very far wrong to say most ventilation openings were never made with any consideration as to economic design for such use. When an air course is required to pass air between different parts of mine workings under a fixed pressure, the size of opening required for a given volume of flow, is, of course, determined by the resistance factor of the air course. It is then impossible to proportion the opening with reference to economics of power consumption, and this paper is limited to the design of openings where ventilation pressure or power consumption may be varied for economic advantage.

Jan 2, 1926

Jan 1, 1936

By John W. Tieman

Coal is a term applied to vegetable matter (trees, grasses, etc.) which was subjected to heat and pressure through geologic ages. This resulted in a change in both the physical and chemical properties. Because its chemical composition is variable, geologists classify coal as a heterogeneous mineral rather than a homogeneous mineral. Peat represents the initial, unconsolidated stage in the development of coal. This coalification continues with time and the application of temperature and pressure to lignite, subbituminous, bituminous, and anthracite toward the theoretical graphite end member. PHYSICAL PROPERTIES OF COAL The physical properties are concerned with the characteristics of coal in its natural state, or prior to its end use as a fuel. For example, the hardness and grindability of coal determine the maintenance cost for coal mining, handling, and pulverizing equipment; the specific gravity of coal and its associated minerals determines the coal preparation technique used in a cleaning plant as well as the capacity of coal bins, boats and size of cargo, and other coal storage facilities. The physical properties are, of course, dependent on the chemical constituents of coal, and all properties are interrelated. Specific Gravity The specific gravity (sp gr) of a solid is the ratio of the weight of a cubic foot of the solid to the weight of a cubic foot of water. The specific gravity of pure coal has been reported to range between 1.23 to 1.72 and increases with the change in rank from lignite to anthracite. This means that it is 1.23 to 1.72 times heavier than water.

Jan 1, 1981

By J. T. Shapland

When externally mounted sliding-gate valves are used to control the flow of metal from ladles, none of the valve components are immersed in steel. In general, the refractories used to date in sliding-gate valves have been made of a high-alumina composition. Because these refractories replace the fireclay sleeves and clay-graphite heads used to construct conventional stopper rods, they represent a major change in the use of pouring-pit refractories, Changes in the well and lining of the ladle as a result of conversion to external flow control probably will not be as severe; however, the sliding-gate valve makes it possible to preheat to a higher temperature and to decrease the turnaround time, and materials more refractory than those currently employed, such as basic brick, might be used in these areas. Another area of pouring-pit refractories that has became quite important is the tundish used with continuous casters. The use of external flow-control devices on tundishes makes it possible to use the tundish for prolonged periods of time and makes the use of better refractories necessary. In this application, high-alumina and zirconia are finding acceptance.

Jan 1, 1972

By William P. Blake

The ancient city of Guanajuato, the capital of the State of that name, has been built up and sustained chiefly by the milling industry based upon the veins of the Veta Madre and La Luz. It is distant about twelve hours, by rail, from the City of Mexico. Its elevation above the sea is about 6300 ft., and it has a salubrious climate. The population, at the date of my visit in 1891, was estimated at from 80,000 to 100,000 persons. The place is justly celebrated for the antiquity, depth and extent of the mines, the magnitude of the deep shafts, and the enormous total yield of the district in silver and gold, which is comparable with that of the Comstock Lode in the United States. Several important public institutions are located at this center. The State office for the records of claims and of the statistics of mining and production is known as the Deputacion de Mineria. The Mining College, with its fine collection of ores and minerals from the mines of the region, is highly interesting to mineralogists. A mint for the coinage of silver, but not of gold, coins from four to twelve millions of' silver dollars annually. The silver received at the mint is melted in an open-hearth furnace, and is ladled out and cast into long and thin bars, which are rolled down to the proper thickness for the blanks. The bars contain some gold which is not parted. There is an export of dore bars to Germany, amounting in value to from $1,000,000 to $1,500,000 annually. There were, in 1891, upwards of forty reduction-works in and about the city where the silver ores were treated, chiefly by the ancient patio method. In these works were 65 Chilean mills, 301 arrastres of large size, and 936 of smaller dimensions. There were 36 steam engines, but mule-power was generally used at the ar-

Jan 1, 1902

By H. R. Wenk

This paper describes a workshop on deformation mechanisms and texture development in rocks. Empahsis is on relating macroscopic mechanical properties with microscopic structures and the methods of their quantitative analysis.

Jan 1, 1982

By Subhash C. Malhotra

This paper discusses the historical background on major sources of obsolete electronic scrap and spent catalytic converter scrap. The paper discusses the principal changes taking place that will affect the future supply of these scraps. The author projects from this background the future opportunities for reclaimers and refiners in these two important segments of the precious metals scrap reclamation industry.

Jan 1, 1984

By P. S. Rudman

Laves phases, AB2, are considered as Izerrzisub-stitutional solutions m1hich are defined by a one-for-truo replacement scheme. Atomic-size tnisfit is considered in terms of deviations of the ratio 2V°b/V°A from unity, where v° = atomic volume. A simple elastic model has been used to calculated deviations from "Vegard&apos;s law of atomic vol-umes". Comparison has been made between calculated and observed atomic-volume deviations fov 222 Laves phases. Agreement is generally very good although there ave some few exceptions which appear to be excusable in terms of electronic changes that ore beyond the scope of the present model. We can consider the formation of a binary sub-stitutional solution A-B from an A solvent as one-for-one replacements of A atoms by B atoms. As the atomic-size ratio deviates from unity, the solution becomes thermodynamically less stable and hence more restricted because of atomic-misfit strain energy. In accordance with our previously presented conclusion1 that the atomic volume, v, is in general the most appropriate measure of atomic size, the ideal size ratio for a binary sub-stitutional solution is vg/vA = 1. The Laves phases have been described by Berry and Raynor2 in terms of various stacking sequences of hexagonal layers of B atoms for the three structures MgZn2(C14), MgCu2(C15), and MgNi2(C36). To form the Laves phase of ideal composition AB, we start with complete hexagonal layers of B atoms in the appropriate stacking sequence and we remove, according to an appropriate scheme for each structure, two out of every four B atoms and replace the two removed atoms by one A atom. We thus might expect to find that the ideal size ratio for the Laves phases is 2v/B/ VA= 1. From this point of view, then, we call Laves phases hemi-substitutional solutions since we employ one-for-two replacements. By analogy with substitutional solutions we can expect for Laves phases that as the ratio 2VB/Va deviates from unity the phase occurrence will be more restricted. Laves3 has plotted the distribution of Laves phases as a function of the radius ratio, ?A/rB, and found that, while the distribution extended from 1.05 < rA/B < 1.50, the

Jan 1, 1965

By E. B. Spice

Although much may be learned about the economics of cold weather operations by studying successful mining ventures in southern and central Canada, it is the purpose of this article to extend the study by considering only permafrost areas. Geographically this means most of the country north of the 60th parallel. In this area, at the present time, only five Canadian companies are carrying on routine and successful mining operations on a year-round basis. However, there have been some score of unsuccessful ventures, and a number of properties in the development stage show promise of being producers. Problems of cold weather are worthy of study. It may be pointed out that successful mines in this area face problems of isolation and costly transportation as well as cold weather. To reach valid conclusions, consider the development of a mythical mineral deposit located on the 65th parallel in the heart of the barren lands; problems of isolation and transportation will be ignored.

Jul 1, 1956

By Fred Allison

THE magneto-optic method of analysis had its origin in experiments1 which were designed to detect and measure a time lag in the Faraday effect and later to study this time lag as a function of the wave length of the light.2 Faraday discovered in 1845 that a beam of plane polarized light, when passed through a transparent, isotropic medium traversed by a magnetic field of force parallel to the direction of the light, suffers a rotation. The direction of rotation is reversed with the reversal of the magnetic field and its magnitude depends upon the strength of the field, the length of the path of light in the substance and the nature of the substance. This phenomenon of magnetic rotation is known as the Faraday effect. A question which had been of some interest for years was whether this power of a liquid to rotate polarized light is acquired instantly with the application of the magnetic field, that is, whether it is a case of instantaneity or whether there is a very small interval of time which intervenes between the application of the magnetic field and the consequent rotation of the light by the liquid; in other words, whether there is a time lag in the Faraday effect. Efforts to measure such a lag previously had met with failure. It was recognized at the outset&apos; that since a time lag had escaped detection it must be extremely small, if to a measurable extent it exists at all. It became necessary therefore to adopt a timing device capable of making measures of almost infinitesimally small intervals. The velocity of light served as this timing device, a modification of a method originally employed by Abraham and Lemoine3 being adapted to the requirements of the problem. Since light travels about 30 cm. in a billionth of a second and since settings in our observations may be repeated with deviations not exceeding 3 mm.,

Jan 1, 1932

By R. Dawson Hall

WHAT are the opportunities for the services of engineers in the coal mines? The best answer perhaps can be made by detailing the present lines of development in the bituminous coal mining regions. They are just at the beginning of a period that can be conservatively termed revolutionary. A few glimpses of new possibilities in economic mining that will reduce the cost of bituminous coal at the mines by at least one half have convinced almost everyone that a change must shortly come about. The cost of housing has become such a burden, especially in mountainous regions, that development which demands the hiring of more men and constructing more houses would not be profitable. The introduction of mechanical aids to mining, transportation and dumping suggests a way of obtaining a large tonnage with the same or a smaller number of men with no further house construction. At the same time the restriction of immigration has made it increasingly difficult to obtain men inured to hard labor. Modern civilization is not productive of muscular energy and at the same time it provides men who are not indisposed to the use of the mental effort required to direct the physical forces now available for the replacement of such energy.

Jan 1, 1924