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By Fred Bond

This paper is a continuation of two earlier papers,1,2 and presents new data on the grindability of various ores and other materials-the results of several years of intermittent research work on the nature of grinding and interpretation of test results. It is divided into five parts: 1. The tabulated results of several hundred grindability tests on a wide variety of ores. 2. A method of correcting screen analyses and calculating from them the surface and other properties. 3. A description of a. new method of measuring the "surface energy" of in ore by pendulum impact tests. 4. Test results. 5. A general discussion of the test results and their application to grinding problems.

Jan 1, 1938

By Henry S. Drinker

The Musconetcong tunnel is situated in New Jersey, near the line of the Central Railroad of New Jersey, about twelve miles from Easton, on the Easton and Amboy Railroad, the latter being the extension of the Lehigh Valley Railroad to tide-water. Up to the present time, the terminus of the Lehigh Valley Railroad has been at Phillipsburg, N. J., opposite Easton, passengers connecting there with New York by the Morris and Essex (D. L. and W.) and New Jersey Central lines; freight and coal being forwarded by the Morris and Essex to tide-water at Hoboken, and by the Central Railroad to Elizabethport and Port Johnson ; also, by the Belvidere and Delaware connections through Trenton to South Amboy.

By Henry S. Drinker

THE Musconetcong tunnel is situated in New Jersey, near the line of the Central Railroad of New Jersey, about twelve miles from Easton, on the Easton and Amboy Railroad, the latter being the extension of the Lehigh Valley Railroad to tide-water. Up to the present time, the terminus of the Lehigh Valley Railroad has been at Phillipsburg, N. J., opposite Easton, passengers connecting there with New York by the Morris and Essex (D. L. and W.) and New Jersey Central lines; freight and coal being forwarded by the Morris and Essex to tide-water at Hoboken, and by the Central Railroad to Elizabethport and Port Johnson ; also, by the Belvidere and Delaware connections through Trenton to South Amboy.

Jan 1, 1875

By Marcus Grossmann

THIS paper offers for consideration certain somewhat radical modifications in the iron-carbon diagram, these modifications being the result of the presence of notable amounts of alloying elements. When only small amounts of alloys are present, 'the standard iron-carbon diagram (Fig. 1) can be used with but insignificant changes; when larger amounts of Chromium, Per Cent FIG. 1.-IRON-CARBON DIAGRAM. FIG. 2.-IRON-CHROMIUM DIAGRAM. alloys are present, however, it assumes a distinctly altered appearance. No comment is offered for the present except to call attention to the delta area, A4BM, which represents a region of mixtures of austenite and delta iron, just as area A3SP represents mixtures of austenite and alpha iron.

Jan 12, 1926

By Rodney G. Ravenscroft

Leasing is not a new phenomenon. Experts have identified its origins as early as biblical times. It is a method of finance that has grown rapidly and is now used in most countries, including those of South East Asia, South America, the Middle East and even the People's Republic of China. Internationally, the leasing world divides fairly easily into two groups and this is determined, by and large, according to whether a country has Anglo-Saxon origins or not. Most of the Anglo-Saxon countries have seen tax-oriented leasing become a sophisticated means of financing the acquisition of large and costly items of equipment and large projects. Countries such as France, Spain and Japan have a highly developed leasing industry but it is not tax-oriented. This paper will not address leasing of this kind. LEASING - THE CONCEPT Wide acceptance of leasing as an alternative for financing capital equipment has grown with the recognition by the users of equipment that it is use and not ownership that generates profits. Whilst this seems obvious, memories of repossession of assets during the Depression and attitudes towards leasing as "last resort financing" have raised strong philosophical resistance that has only recently begun to be overturned. A financial lease is a commitment by way of contract between a user of equipment (lessee) and a financial owner (lessor) under which the lessee makes a series of payments in return for use of the equipment. The lessee is acquiring economic value associated with ownership but not ownership of the equipment itself - that remains with the lessor. A lease is a method of financing the use of an asset; other methods finance the assets themselves. It is the taxation aspects that then become important. The lessee is giving up some or all of the taxation benefits of ownership such as depreciation and investment tax credits. The lessor claims these benefits, as he is entitled to do as owner, and takes them into consideration when determining the level of lease payments that are necessary to generate his required rate of return. These lease payments are, of course, lower than they would have been without those taxation benefits. The lease payments themselves are fully tax deductible. This is tax shelter leasing. The lessor is acquiring taxation deductions that are applied fully and immediately against his other taxable income so as to reduce the amount of tax he is to pay to the revenue authorities. It is this concept that makes financial leasing work. Governments provide incentives by way of tax concessions to encourage capital investment. Governments presume that prudent capital investment will offer employment opportunities, generate sales and streamline economic activity. These, in turn, will lead to the collection of government revenue. It makes no difference at all whether these incentives are claimed by a commercial or industrial owner/user or by a financial owner who makes equipment available for use by industry. Rather, the issue is to ensure that if an incentive is available, it is used so as to achieve its desired results. No greater or lesser incentive is available for leasing and leasing does not misuse the taxation aspects of equipment ownership. The critical issue is whether the full value

Jan 1, 1985

By A. S. Emanuel

A correlation has been developed for calculating the phase behavior of, gas-condensate systems at reservoir conditions. The correlation is based on the principle of corresponding states and has been coded for an IBM 7094. Experimental K-values were determined for several gas-condensate systems at reservoir conditions to evaluate various semi-empirical parameters of the correlation. The approximate range of application of the correlation is 150 to 300F and 1,500 to 6,000 psi. INTRODUCTION The rapid development of digital computers during the past several years has made feasible the calculation of hydrocarbon phase behavior by methods based on rigorous thermodynamic principles. Good correlationsl have been developed for low to moderate pressures, but these techniques have not yet been extended successfully to reservoir fluids at high pressures. Consequently, the determination of phase behavior of oil and gas systems at reservoir conditions is still based almost entirely on generalized data correlations or on experimental studies of the fluid in question. While these methods have been used successfully many times, they do have inherent limitations that restrict their applicability. Generalized correlations, such as the NGShlA K-charts, are limited to the range of pressure, temperature and components for which the data were determined. The accuracy of these correlations is often questionable because the effect of total system composition is not well defined. Experimental studies offer a reliable method for determining phase behavior, but usually the studies are costly and time consuming. Recently, Leland and co-workers presented a new approach to calculating phase behavior from the principles of corresponding states.6-8 Corresponding states methods determine the thermodynamics properties of a given system by comparison with a reference substance whose properties are known. The accuracy of this approach depends on close chemical and structural similarity between the reference substance and the system in question and between components within the system itself. For high accuracy, it is usually necessary to correct for chemical and structural dissimilarities. In principle, however, the corresponding states method should be no less accurate at high pressures than at low pressures, provided reference substance properties are known. This paper describes an empirical modification of the basic correlation proposed by Leland, et al.6 for the specific purpose of calculating the phase behavior of gas-condensate fluids at reservoir conditions. The modified correlation, which has been programmed for an IBM 7094, may be used for either approximate or precise determination of fluid behavior depending on the amount of analytical and, experimental data available for the system. BASIC THEORY The basic theory of the corresponding states phase equilibria correlation was first published by Leland, Chappelear and Gamson.6 Subsequently, Leland, Chappelear and Leach published methods for improving the accuracy of the original theory.7-9 The aim of the correlation is to calculate the K-value of each component of a given system as a function of pressure, temperature, and over-all composition, where Once the K-values are known, the phase behavior may be determined directly by an appropriate flash calculation. The basic equation for calculating component K-values was taken from the work of Joffe. 4 For any component i of a mixture, the K-value is given by

Jan 1, 1969

By Philip B. Bucky

[CONTENTS t. How Does One Determine WhetherPAGE an ore Body Will Block-cave?R. W. Hughes13 Sherman R. Burdick 13 PAGER. T. Gallagher 14 Mark A. Smith 2 C. F. B. Price, Jr.14 Harry A. Leidich2Benjamin F. Tillson 14 McHenry Mosier2C. F. Jackson14,17 R. W. Hughes2R. Taborelli15 Sherman R. Burdick3Frank A. Ayer16 R. T. Gallagher 3Philip B. Bucky16 Benjamin F. Tillson 3Rollin Farminr6 Lucien Eaton 3J. L. G. Weysser15, 0,17 C. F. Jackson 3George S. Rice17 Philip B. Bucky32. How Does One Determine the Block4. What Determines the Procedure in Dimensions and the DevelopmentRemoving Caved Ore? Work Necessary to Make an OreHarry A. Leidich17 Body Cave?McHenry Mosier17,21 Mark A. Smith 5,7,() R. W. Hughes17 Harry A. Leidich6Sherman R. Burdick 18 McHenry Mosier6,7,12 R. T. Gallagher 18 R. W. Hughes6Mark A. Smith I8 Sherman R. Burdick 7Philip B. Bucky20, 21, 23 R. T. Gallagher 7C. F. B. Price, Jr20 Benjamin F. Tillson 7,11R. H. Bennett21 L. E. Young7C. F. Jackson 21, 23 Robert D. Hoffman8, 1 2Gerald Sherman 3 . 21 Gerald Sherman8Tell Ertl21 Philip B. Bucky10, 11, 12G. K. Foster 23 R. S. McClellan 12C. H. Shoemaker23 Tell Ertl 12 3. How Do the Forces Act and What Are5. What Are the Criteria for Determining the Stresses Developed in a Blockthe Efficiency of a Block-caving That Cause It to Block-cave?Operation? Mark A. Smith 12, ISHarry A. Leidich23 Harry A. Leidich13McHenry Mosier24 McHenry Mosier13R. W. Hughes24 Sherman R. Burdick 24 R. T. Gallagher 24]

Jan 1, 1942

By E. P. Polushkin

The object of this paper as to show that the structural composition of an alloy may be found by the planimetric measurement of the total area occupied by each of the constituents on a few representative photomicrographs of this alloy. When the area is determined the volume and the proportional weight of the constituent may be calculated. This method has been used for the determination of the structural composition of binary eutectics and other binary alloys with known constituents; also the composition of unknown constituents in binary alloys. The accuracy of the method is. high enough to justify its application to metallographic problems instead of the chemical analysis. THIS work has for its purpose the establishment of a new method for determining the structural composition of alloys. The area occupied by a constituent on a few representative photomicrographs of the alloy is measured, by a planimeter, especially designed for metallographic work, and the volume and proportional weight of the constituent calculated. Experiments have shown that 'the results are accurate enough to justify the application of the method to many problems in metallographic research instead of chemical analysis. The advantage of the method is the possibility, of determining the amount of the constituents with-out separating them from the alloy; their composition may also be determined if the ultimate chemical analysis of the alloy is known. DESCRIPTION OF PLANIMETER Suppose Fig. 1 represents a part of a photomicro-graph on which the total area of the black figures is FIG. 1?-PART OF PHOTOMICROGRAPH ON WHICH TOTAL AREA OF BLACK FIG- URES IS TO BE FOUND. to be found. By a system of parallel lines drawn short equal distances apart all figures may be divided into trapezoids. As the area of a trapezoid is equal to its median multiplied by its altitude, the relation between the total areas of the black and the white figures comprised within each strip is equal to the relation between the sums of medians for these figures respectively.

Jan 12, 1924

By Paul Merica

ONE of the most useful, and at the same time least commonly used, methods of thermal analysis for the determination of transformations in metals and alloys consists in the recording of the tune intervals required for successive increments of temperature change during heating or cooling, the temperature of the furnace containing the specimen being altered at a uniform rate. The curve obtained by plotting these time intervals as a function of the mean temperature of the specimen during the interval is called the inverse-rate curve. It is probably due to the fact that no simple and convenient method has apparently been available for the measurement of the successive time intervals that this method has not been so generally used as, for example, the differential method, for which several tykes of automatic or semi-automatic apparatus have been designed. Whenever this method has been used, the intervals have usually been measured with the use of a chronograph; its operation as practised at the Bureau of Standards' is as follows: The temperature of the specimen is measured by a thermocouple and a dial potentiometer. The operator sets the potentiometer at successive values of the electromotive force differing by equal increments, usually 0.02 millivolt, and records the exact instant on the chronograph, by pressing a contact key, at which the galvanometer coil passes through its null position. Two-second intervals are also recorded on the chronograph record, and the number of 'seconds elapsing between successive signals is afterward counted from the record and plotted as a function of the electromotive force or of the temperature. This is an admirable method and by it most minute thermal arrests may be detected, but it requires a good chronograph, which is generally difficult to obtain, and the time of one operator during the recording and, subsequently, to read the intervals from the record; the latter operation often takes from one to two hours.

Jan 7, 1919

ROSWELL H. JOHNSON,* Pittsburgh, Pa.-The industry, I think, has suffered very severely from the lack of just such work as has been done by Messrs. Lewis and Beal. I think we owe a great deal to the Bureau of Mines for at last undertaking this much needed work, even though it is so belated. It could have been of very great assistance in so many properties where its usefulness has now passed. I think it is perhaps well to sound a note of caution, owing to the fact that so much of this information was derived from eastern Oklahoma; but with the new bulletin giving the decline for many fields, there will be far less danger of falling into error through assuming too much uniformity. The cumulative percentage curve seems to 'me to be a. particularly splendid idea. It should have a very important -influence, especially as the authors have themselves pointed out several variables that ought to be taken into consideration. The thickness, I think, is going to be an especially important one to work out along the general lines of method that they have advanced. Probably the most surprising thing in the paper is the general rule that the decline of a well is more correlated with its size than with its age. I can't help but think that that generalization, important as it is, is rather rough and will not apply so clearly when we have a larger number of fields before us. Still the generalization, rough as it is, is of very great importance, since the industry has been very largely basing a great many of its ideas on the ignorance of that principle. It leads to certain corollaries that are of great consequence. The first is that the undrilled portion of the property must be appraised on a. different basis from that used for the drilled portion.

Jan 4, 1918

By Morris Cohen

This paper deals with the calculation of the composition of the infinitesimal trace of alloy that transfers from the liquid to the solid state at each temperature during the equilibrium solidification of a binary solid solution, and which thereby enables the compositions of the coexisting liquid and solid phases to follow along the liquidus and solidus lines respectively during the cooling. A general expression for the composition (d) of the liquid-to-solid transfer at each temperature has been derived: d = ZLXL(XL - P) + Zsxs(P- ZL(XL - P) + Zs(P - Xs) where ZL and Zs are the slopes of the liquidus and solidus lines at the given temperature, XL and xs are the composi-tions of the stable liquid and solid phases at the same temperature, and P is the composition of the alloy under considera-tion. The d equation is valid for the process of equilibrium heating as well as cooling, and may be applied to vapor-to-liquid, vapor-to-solid, liquid-to-liquid, and solid-to-solid transfers if the corresponding equilibrium diagrams are known. The d -versus-temperature curves for two alloys Pl and P2 are shown in Fig. I. In each case, the liquid-to-solid transfer has the same composition as the stable solid FIG. I.-GENERAL SOLID SOLUTION DIAGRAM SHOWING S CURVES FOR ALLOYS P1 AND P2. phase only at the temperature of the be-ginning of solidification, and has the same composition as the stable liquid phase only at the temperature of the completion of solidification. At each intermediate tem-perature, the composition of the liquid-to-solid transfer differs by a finite amount from those of the two coexisting phases. Therefore, during equilibrium cooling, the transfers must merge into the solid phase from the liquid without forming a transition phase; otherwise the condition of equilibrium would be violated. At any given temperature during solidification, the composition of the liquid-to-solid

Jan 1, 1940

The House Committee of the Engineering Societies Building has lent to he members of the three welfare committees a room on the ground floor of the building where they can carry on some of their war activities. Two sewing machines and two knitting machines are installed there and ladies are invited to sew for the Foreign War Relief Committee and knit for the Emergency Committee, which is working for the 27th Engineers, a special mining regiment. The Emergency Committee, Mrs. H. Norman Spicer, Chairman, reports the formation of a committed of 21 members. The organization meeting was held March 7, and plans were made for future activities as follows: A letter was read from Mr. Ingalls asking for 72 sweaters, 72 helmets, 66 pairs of wristlets as well as 772 pairs of socks, 272 being for immediate delivery. To meet this request it was decided to secure the helmets and wristlets from the Navy League, and to undertake the making of the sweaters and socks ourselves. Accordingly Mrs. H. N. Spicer and Mrs. J. H. Devereux were empowered to buy wool in sufficient quantities, and woven material for the 72 sweaters, sending the bills to Mr. Ingalls, who had guaranteed the money from the Engineering and Mining Journal. This was attended to promptly, and the materials were ready for distribution to the committee on March 13. After considerable difficulty, knitting machines for the socks were discovered and the agent came to demonstrate them. Mrs. Spicer gave one to the Committee and Mr. Ingalls has guaranteed the money to buy two when the manufacturers can deliver them. Up to April 6, 130 pairs of socks, machine and hand-knitted, have been handed in-also 68 sweaters, 80 helmets and 90 pairs of wristlets. It has been calculated that it needs five women knitting behind each man at the front to keep him continuously supplied with knitted garments.

Jan 5, 1918

By Samuel Hoyt

THIS paper gives a brief description of an investigation made several years ago on the diffusion of zinc into copper. The material for that study was furnished in the form of thin copper strips coated with zinc. The result was required rather quickly and at not too great an expense, and especially information was desired as to the rate at which zinc would diffuse from the zinc coating into the copper and the temperature at which the operation should be carried out. A study of the requirements of this problem indicated that the solution might be secured by means of six determinations. This is the smallest number that will give the information desired and, at the same time, furnish checks on the accuracy of the determinations which justify an abbreviated experimental program. This does not count a preliminary test which was designed to give some idea of the correct temperature to use. The minimum number of temperatures that can be used is two. Knowing the rates of diffusion of zinc into copper at two properly chosen temperatures, it is possible to calculate the rate for any other temperature, and also to check the accuracy of the determination by means of the heat of diffusion, which is calculated from the effect of temperature on the rate of diffusion. The minimum number of determinations at any one temperature is three. The amount of diffusion which occurs at a fixed temperature is definitely related to the time of diffusion, so that by determining the amount of diffusion for three different time intervals, this relationship may be established and possibly a check on the accuracy may be secured. This accounts for the six determinations or experiments, and suggests the logical plan of the work. The check used here is not generally applicable to diffusion phenomena, but it seems to hold closely enough for the limited amount of diffusion in this investigation to justify its use.

Jan 1, 1928

By Advisory Editorial Board

FOR many years there has been no book that adequately represented the present state of the art of coal preparation-an art that has been rapidly changing during the passing years, and particularly during the last ten or fifteen years. In fact, changes of preparation have been so rapid that no book could keep abreast of their progress, and even the Proceedings of the technical societies have not been able to do so. It has been the intention of this committee and of the editor to make this book as nearly up to date as possible and to make it one that would appeal primarily to operating men, while at the same time adequately showing the theory back of the many processes used. The start of the war and the increased calls upon the time of the authors selected for the various chapters have slightly dimmed the brightness of the ideal intended, but the result undoubtedly brings the practice of preparation and its literature closer together than they ever have been before. It is the hope of the committee that this book will be useful both to those whose daily work is concerned with preparation and to consumers who use the product produced at the many fine and up-to-date coal plants throughout the country, which are now producing, as they always have done, all the coal needed by this country in its greatest crisis. While the committee has exercised a general supervision over the preparation of the various chapters, all of the correspondence and edi¬torial work have been done by Prof. David R. Mitchell, and it has been his untiring interest and devotion that have made the book possible-the credit is all his. Advisory Editorial Board, B. M. Bird Cadwallader Evans, Jr. Thomas Fraser W. H. Lesser William C. Mcciilloch J. B. Morrow H. S. Salmon Raymond E. Salvati Kenneth A. Spencer H. F. Yancey Howard N. Eavenson, Chairman.

Jan 1, 1943

By Thomas E. Howard

Tunneling is at the threshold of a new era. An exciting new technology is becoming available. And, supplying the increasing quantities of minerals required by a growing and socially advancing world population, together with providing the subsurface facilities attendant to the rapid urbanization of the more developed countries of the world, will require underground excavation during the next decades on a scale that would have seemed fantastic a few years ago. It is estimated that world mineral consumption will increase fivefold by the year 2000. Projections for the United States indicate that domestic consumption of nonfuel minerals may increase two to three times by the end of the century. Meeting these requirements will entail opening up many new underground mines, even if present trends toward surface mining continue. And, at least in the United States, new factors that are becoming increasingly important may modify these trends. We are depleting our shallow easy- to-find and easy-to-mine mineral deposits; and, if we are to avoid becoming dangerously dependent on imports, we must turn more and more toward deeper deposits that are not amenable to surface mining. Growing public concern with environmental quality is apparently leading toward increasingly stringent regulation of surface mining which also will tend to make underground mining economically more attractive. The world market for underground construction is also growing rapidly. The most conservative projections indicate that in the United States alone more than $7.0 billion will be spent on excavation for underground facilities during the next ten years. And these estimates do not include any of the bold, imaginative new applications for underground excavation that have been proposed, such as extensive underground power transmission, the Chicago Deep Tunnel plan, and the Northeast Corridor Transportation project. There can be little doubt then that the market for tunnels for conventional applications is increasing rapidly and that the trend will continue. It

Jan 1, 1970

By A. K. Schellinger, R. D. Lalkaka

IF the ball mill is considered only from an energy standpoint, it can be thought of as a converter of kinetic energy into heat energy and surface energy. The law of the conservation of energy must apply to the ball mill as it does to any machine or process in nature. The heat energy output of the ball mill is apparent to any casual observer of the operating mill since the outflow pulp will be appreciably warmer than the inflow water and rock. The rock in the ball mill is crushed by shearing of its ionic bonding caused by some impact-induced stresses beyond the elastic limit. As the bonds holding the mineral crystal lattices together are ruptured, new surface area is created on each unit of which a definite number of unsaturated bonds exist. Such unsaturated energy of bonding may be termed the "surface energy," and is a potential energy figure. This created energy was withdrawn from the ball mill system and represents an absorption, or disappearance of heat. To reduce the size of the rock, surface area must be created and with it the at- tendant characteristic surface energies of the minerals concerned. Thus the creation of surface energy, from an energy viewpoint, is the creation of useful work by the ball mill. Because of the controversial nature of the energy efficiency figures for modern operating ball mills, it seemed worthwhile to approximate the ordinary magnitude of such efficiencies from the above viewpoint. This was done by an energy balance of the three aforementioned forms of energy, kinetic, heat, and surface energy, for two 9Y2x10-ft grate-type ball mills grinding cement raw materials. Kinetic energy input to the balls was approximated as closely as possible while the heat energy output was measured by means of a thermometer and water and rock flow rates. The assumption was made

Jan 1, 1952

By Paul D. Merica

One of the most useful, and at the same time least commonly used, methods of thermal analysis for the determination of transformations in metals and alloys consists in the recording of the time intervals required for successive increments of temperature change during heating or cooling, the temperature of the furnace containing the specimen being altered at a uniform rate. The curve obtained by plotting these time intervals as a function of the mean temperature of the specimen durnig the interval is called the inverse-rate curve. It is probably due to the fact that no simple and convenient method has apparently been available for the measurement of the successive time intervals that this method has not been so generally used as, for example, the differential method, for which several types of automatic or semi-automatic apparatus have been designed. Whenever this method has been used, the intervals have usually been measured with the use of a chronograph; its operation as practised at the Bureau of Standards1 is as follows: The temperature of the specimen is measured by a thermocouple and a dial potentiometer. The operator sets the potentiometer at successive values of the electromotive force differing by equal increments, usually 0.02 millivolt, and records the exact instant on the chronograph, by pressing a contact key, at which the galvanometer coil passes through its null position. Two-second intervals are also recorded on the chronograph record, and the number of seconds elapsing between successive signals is afterward counted from the record and plotted as a function of the electromotive force or of the temperature. This is an admirable method and by it most minute thermal arrests may be detected, but it requires a good chronograph, which is generally difficult to obtain, and the time of one operator during the recording and, subsequently, to read the intervals from the record; the latter operation often takes from one to two hours. There is here suggested a simple, convenient, and, it is believed, equally accurate method of recording the successive time intervals, by which the

Jan 1, 1921

By J. W. Leonard

This expanded and more detailed supplement to earlier published work1 is offered as a means to demonstrate the high empirical correlation which exists between the readily measured coal bench scale test parameters of volatile matter (d & a.f.), Hard-grove grindability index (HGI), Koppers cone bulk density (BD) and pulverization level (% passing a 1/8-in. screen) to the less readily measured full scale coke stability index. Thus, Fig. 1, 2 and 3 represent the correlated test data contained in Tables I, II and III respectively. Ninety-six coals are correlated so that 97% of the resultant cokes fall within two points and 100% fall within three points of the actual tested coke stability indices. The main generalizations which can be drawn from the correlation of these coals are as follows: 1) The coke stability indices for higher bulk density coals (46.0 BD to 50.6 BD) appear to be largely influenced by differing combinations of factors for coals above and below a pivotal point of approximately 36% to 37% volatile matter. Below this pivotal volatile matter coke stability index appears to be influenced largely as a result of changes to the coal volatile matter and pulverization level. While above this pivotal volatile matter coke stability indices appear to be dependent on the coal hardness, as measured by the HGI, and to some extent upon coal volatile matter. Pulverization appears to have little influence on the coke stabilities of the harder coals (52 HGI to 58 HGI) of greater than 36% to 37% volatile matter. 2) The coke stability indices for lower bulk density coals (41 BD to 45.9 BD) appears to be largely influenced by changes to coal volatile matter and pulverization level for softer coals above approximately 58 HGI. 3) The main empirical observation to be drawn from these results is that for coals above approximately 36% to 37% volatile matter the quantities of hard and soft constituents as measured by the HGI are important when defining coal rank for correlation to the coke stability index.

Jan 1, 1965

By Richard W. Markley

A centralized online data acquisition system has been developed by the U.S. Bureau of Mines Pittsburgh Mining and Safety Research Center for rapidly digitizing, storing, and processing experimental signals originating up to 1100 feet away from a central computer. This system, which services seven laboratories, is currently based on a CDC System 17 1/- computer with 56K of semiconductor memory, four disk drives (one shared online with a CDC 1700), two magnetic tape drives, high-speed A/D hardware, and other input/output peripherals. The laboratories are linked to the central computer by 15-pair cables and signal conditioners and to the computer's communications controller by modems and current loops. The A/D throughput rate is approximately 30,000 samples per second (9 bit plus sign resolution) and permits scanning about 30 instruments once every millisecond for up to 100 seconds, being limited only by disk capacity. The laboratories serviced by this facility conduct explosions research and include such facilities as an Experimental Coal Mine Explosion Facility (45 channels), a Constant Volume Combustion Laboratory (4 channels), and a Simulated Coal Mine Laboratory (15 channels). Personnel support includes one systems analyst, two applications analysts, one operator, and a hardware technician. The system has performed adequately for burst-type data acquisition, but due to a lack of long-term reliability (24 hours) of the real-time multiprogramming operating system and unpredictable power failures, slow phenomena signals are generally digitized and stored offline. This latter data is input to the computer through peripherals such as a high-speed paper tape reader, or high-speed asynchronous communications ports. Processing of data is done either in real-time (as soon as data is collected) or in batch mode. Smaller batch jobs are run on this computer, and all others are transmitted by means of the system's high-speed UT 200 terminal simulator to a CDC-6000 series computer.

Jan 1, 1977

By Gram Curtis

The apparatus described below for the handling of plates upon their delivery from the rolls, embodies features believed to be of interest to those contemplating the building of new plate-mills, and also to such owners of existing mills as may be considering the improvement of their works. The points to which attention is called are the small space required for the finishing-end of the mill, and consequently the very moderate size of the building for the amount of plates handled; the directness and ease of manipulation, and therefore the mall amount of labor required; the distribution of plates; the facilities and time allowed for their cooling. These, together with other features of detail and general arrangement scarcely less important, will become apparent when the descriptions and illustrations herewith given are understood. As these devices deal with the finishing of the plates only, they may be added to any plate-train when the floor-space and the building are large enough to permit their introduction; and it will be obvious that the features of this method, more or less modified, are applicable to any existing mill. Figs. 1 and 2 show a three-high 32-and 19- by 120-inch Lauth mill, with hydraulic lifting-tables, served by four heating-furnaces, with hydraulic cranes for charging and drawing. Upon leaving the rolls, the plate is allowed to rest with its forward edge projecting somewhat beyond the end of the catcher's table. Here it is seized by the automatic tongs, A, suspended from a buggy travelling in the overhead trough, B, and actuated by the hydraulic cylinder, C. These tongs are operated by a boy, who stands several feet from the heated plate, and controls the long light handle, D, shown in the plan, Fig. I. His duty is merely to advance the tongs by means of .the hydrulic cylinder, C, to raise or

Jan 1, 1892