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By G. H. Ashley

THE Pittsburgh coal bed stands today: as probably the largest contributor of wealth of any single mineral deposit in the world. If it is not, what other deposit is? To the present it has contributed more than 2,530,000,000 tons of high-grade coal from Pennsylvania alone, worth nearly $4,000,000,000. Since 1910 it has added more than $2,500,000,000 to the value of Pennsylvania's mineral output. There is estimated to be about three times as much coal still in this bed as has been mined. To realize the full value of this wonderful bed it must be remembered that the figures given are for one State only. To them should be added the figures for the same bed from West Virginia, Ohio and Maryland. Furthermore, as known by man, this great deposit is only a fraction of its original whole. Outliers in Somerset County, Pa., indicate that its original extent in Pennsylvania in an east and west direction was more than two times its present extent. Add to that the northward extension as indicated by outliers in northern Allegheny, Armstrong and Indiana counties,, and it seems safe to say that its original extent was not less than three times the area at present underlain by it. And as the subjacent beds of the Allegheny group are found still further eastward and northward, it is at least a possibility that it originally covered an area many times its present area.

Jan 10, 1926

By R. W. Raymond

This paper is simply a summary, prepared at the request of the Council of the Institute, of the report of Mr. Albert Ladd Colby, of South Bethlehem, Pa., presented at the New York meeting (October, 1896) of the Association of American SteelManufacturers, on " The Advisability of the Endorsement by the Association of the United States Standard Gauge, approved by Act of Congress, March 3, 1893, to the Exclusion of the Birmingham Gauge, the .Brown and Sharpe, and all Others:" a subject on which, at the Pittsburgh meeting (April, 1896) of the said Association, Mr. Colby had been appointed as a committee. The report favors the adoption, not of the United States standard gauge to the exclusion of others, but of a decimal system of gauging all materials in thousandths of an inch, thus doing away entirely with arbitrary gauge-numbers running in inverse order to the actual thickness. The American Institute of Mining Engineers originated this movement. The report of its committee on a standard wiregauge, presented in October, 1877,* recommended the abandonment of the system of fixed gauges for commercial use, and of the system of representing the diameters and sizes by numbers, and the adoption, in lieu thereof, of the system of expressing sizes in thousandths of an inch or fractions of a millimeter, and the use of the micrometer-gauge as a means of measuring sizes. In 1892 the American Society of Mechanical Engineers appointed a similar committee, and corresponding action was

Jan 1, 1898

By Frank S. Shuri

INTRODUCTION The Calumet Pumping Station, located on the south side of the Greater Chicago area, is part of the Tunnel and Reservoir Plan to accomodate the city's wastewater. The Station consists of two parallel rock caverns, each 18 m high, 20 m wide, and 62 m long, located in Silurian dolomite approximately 91 m below the ground surface. The caverns are oriented N-S with a 24-m-wide pillar between them. Prior to construction, rock mechanics studies were conducted in an L-shaped test adit at the location of the west cavern. The purpo3e of the rock mechanic studies was to characterize the site, particularly the in situ stress field and deformation characteristics of the rock. This information, together with other physical properties of the rock and geologic data, was used to evaluate the stability of the preliminary cavern design, with particular emphasis on cavern orientation, rock reinforcement, and pillar stability. GEOLOGY OF THE SITE Stratigraphy The Chicago area is located on the Kankakee Arch, a broad, gently sloping arch of Paleozoic sediments. Rocks in the project area consist of Silurian dolomites unconformably overlain by Pleistocene glacial deposits. The formations of interest to this study are: - Racine Formation, inter-reef facies. This dolomite is gray- brown, silty, and compact. It contains occasional prominent bedding surfaces. The Racine Formation in the project area varies from 73 to 74 m in thickness.

Jan 1, 1984

By P. St. J. Perrott

AN explosive of balanced composition might be expected, on first consideration, to develop maximum propulsive strength.1 This hypoth¬esis is based on the assumption that an excess of oxygen would act simply as an inert material with a consequent lowering of flame temperature, also that a deficiency of oxygen would tend toward incomplete reaction of the combustible materials, thereby preventing development of the full strength of the explosion. Actually, however, it can be shown both theoretically and experimentally that an explosive having a certain oxygen deficiency will develop the greatest propulsive strength. This fact has been known to the technical staffs of explosives manufacturers for many years, but it has not always been recognized by explosives engineers in the field. For example: There is a fairly widespread opinion that the wrapper of a stick of dynamite is merely a container for the explosive and that it plays little if any part in the development of propulsive strength. Actually, it can be shown that the wrapper enters fairly completely into the explosive reaction. In the case of most gelatin dynamites, a given weight of explosive from which the wrappers have been removed will develop considerably less strength than the same weight of explosive plus wrapper, in spite of the fact that the latter combination contains less weight of the actual explosive ingredient. It can also be shown that a cartridge 7/8 in. in diameter may be stronger, weight for

Jan 1, 1928

By Robert H. Hafner, Irvin R. Kramer, Stewart L. Toleman

IN his paper on the calculation of hardenability from chemical composition, Grossmann1 discussed the effect of most of the alloying elements used commercially. The purpose of the work reported in this paper was to determine the effect of several other elements on hardenability-arsenic, antimony, beryllium, cobalt, columbium, germanium, tellurium, tin, aluminum, and titanium-and to extend the range of composition of some of the elements studied by , Grossmann-chromium, copper, manganese, molybdenum, nickel and silicon. EXPERIMENTAL METHODS To determine the effect on hardenability, suitable amounts of the alloying elements were added to experimental heats and the hardenability determined by means of end-quenched hardenability specimens. The steels were melted in a high-frequency induction furnace with a basic crucible, using ingot iron as a base for some of the heats and S.A.E. 1015 for others. The alloying additions were made as ferroalloys or as metal, depending on the ' alloying element. Hundred-pound heats were split and poured into square, tapered, cast-iron ingot molds with hot tops. Aluminum was not used as a deoxidizer in most of the heats. The ingots were homogenized for 12 hr. at 1260°C. (2300°F.) , and forged into rounds of 1 ½ in. diameter. These bars were normalized twice from 840°C. (1550°F.) before machining into Jominy bars. The composition of the steels was deter- [ ] mined in most cases by samples taken from the end-quench hardenability specimen. As suggested by crafts,2acid-soluble

Jan 1, 1943

By Robert W. Zimmerman

POROUS SOLID COMPRESSIBILITIES There are four different compressibilities associated with porous solids, each relating the fractional change in either bulk volume or pore volume with the change in either pore pressure or confining pressure. These will be referred to as Cbc, Cbp, Cpc, and Cpp, with the first subscript denoting the relevant volume, and the second subscript denoting the relevant pressure. They are defined as: [ ] Note that minus signs are included in two of the definitions so that each of the compressibilities will always have a positive value. In general, each compressibility depends on the elastic moduli of the matrix material, the porosity, and the exact geometry of the pores. Taking the latter factor into account calls for separate analysis for each different pore shape, which of course can only be attempted for a few relatively simple cases. But lower bounds for each of the four compressibilities can be found, independant of pore structure, in terms of only the porosity (0) and the elastic moduli of the matrix material (any pair chosen from K, E, G and V). The first step is to find relationships between the four compressibilities, starting with the following observation: If a porous solid made of a linear elastic, isotropic and homogeneous matrix material is subjected to uniform hydrostatic pressure of magnitude P on its external and all of its internal (pore) surfaces, the state of stress in the solid will be exactly the same as that which would occur

Jan 1, 1982

By D. L. Harris, A. M. Gaudin

THE following results, presented here in condensed form,1 were obtained in a preliminary study of the adsorption of n-hexane thiol, hexyl mercaptan, on sphalerite, zincite, willemite, and quartz, from aqueous solution and from a gas. Interest in this subject was aroused by a Belgian report2 of effective use of hexyl mercaptan for flotation collection of oxidized zinc minerals. The relatively low boiling point, 149°C, of the mercaptan3 suggested the desirability of extending the usual measurements of partition of collector between aqueous solution and gas and between gas and mineral. It is believed that this paper presents the first measurements of this type on a flotation system. Attempts were made to carry out the measurements at equilibrium, but as the work progressed it became increasingly doubtful that this desirable condition had been achieved. To control composition and extent of the gas phase, the apparatus was a wholly-enclosed thermally-controlled glass system. Because of these constraints and the desirability of dealing with pure minerals, a scale of operations was chosen in which a few grams of deslimed mineral were used in each test. It was also necessary to choose a particularly sensitive method for mercaptan analysis, and in fact a method that would permit the experimenters to follow the approach to equilibrium. For these reasons mercaptan marked by radiosulphur 35 was used. An analysis was made for the radiosulphur by a modification of the method of Gaudin and Carr.4

Jan 9, 1954

By Richard L. Ash, Thomas E. Pearse

Most theories of blasting phenomena are based on the condition that explosive charges have a spherical shape. If a cylindrical charge is considered, the explosive is usually assumed to have an infinite velocity of detonation. Another limitation is also often imposed whereby only one free face is considered to exist. Unfortunately, these conditions all serve to limit the number of variables involved and tend to over-simplify analyses. The result is that explanations for actual effects from blasts are seldom realistic. In addition, no solution has yet been found to explain the actions of certain blasting agents that appear to stress materials in a different manner than do many of the high explosives. In order to determine causes for some of the unexplained phenomena, investigations were conducted by the writers on both actual field blasts and theoretical problems. Although many solutions have been proposed to explain the rock breakage processes, none relate the effects of hole depth, explosive and rock energy- propagation velocities with charge placement geometry. Evidence indicates there is a definite interdependence of those factors and that they are of vital importance in proper drill-pattern design. For simplicity most of the discussion in this paper applies to vertical blast-holes drilled in uniform massive rock for open pit blasting, although the basic principles presented apply to all forms of blasting with certain basic modifications being necessary for specific field conditions.

Jan 9, 1962

By William C. Buell

As used in connection with open-hearth or other high-temperature operations, "insulation" refers to a multitude of substances, natural or manufactured, that have the one principal property of preventing the flow of heat by conduction to a greater degree than refractories can prevent it, the principal properties of the latter being resistance to temperature and/or chemical action. The term "control" as commonly applied to the mechanization of management functions is inappropriate without qualification, for without some degree of control of every operation we could produce no steel worthy of the name. Although grouped together in this paper, insulation and control in open-hearth furnaces have little, if any, interrelationship, therefore the paper is made up of two distinct parts. INSULATION OF OPEN-HEARTH FURNACES More than ten years ago the writer proposed the insulation of an acid open-hearth furnace system below the charging floor, and it was accomplished, with gratifying results. Possibly that was the first time the insulation of regenerators and slag pockets of any open-hearth furnace was undertaken, but shortly thereafter such insulation became general, and when the six groups of 15D-ton furnaces' were built in 1929-1930, they were completely insulated below the charging floor. While the practice was accepted at least five years ago, it was not well understood, however, as indicated by the following incident which occurred in connection with an installation made in 1929. After the

Jan 1, 1935

By Howard V. Sears

ArcHodrilling (Arcuate Hole Drilling) of short radius overhead curved holes from within the working level with a new, small-diameter in-the-hole drill produces tangible, assayable chip samples from the entire height of the projected mine level where the hole arcs down immediately in front of the working face. Drilling through the projected level with diamond coring tools produces samples showing the competence of roof and floor strata as well as the geological and economic characteristics of the ore. Hand-portable solid state electronic surveying instrument has been developed to survey the ArcHole and a convenient nomograph plotting record sheet converts survey digital readouts to hole inclination in degrees, to radius of curvature in feet, and to attitude of the plane of curvature from vertical in degrees, all without calculation. The ArcHodrilling system offers a tool with which the exploration geologist can more nearly assess the true potential of old mining properties being reexamined and to reduce the number of surface diamond drill holes needed to secure development data about new ore bodies. It gives the mine geologist an opportunity to secure those data at a fraction of the cost of drilling from the surface. The mining supervisor has a convenient, cheap tool to look ahead to know what he will be mining tomorrow. The mill supervisor has an opportunity to reduce his mineral loss in tailings by being able to anticipate the grade of his mill feed.

Jan 1, 1973

By Y. Astafyev

In applying computers at the enterprises it is necessary to develop an open-pit model which completely corresponds in its structure, properties and characteristics to real open-pit mining. This model is used for controlling open-pit operations which ultimately define the system controlling ore reserves. The preparation and reserving of the latter are highly expensive and labour-consuming, therefore the investigations are aimed at developing the ore reserve control system which is capable to provide open- pits with the necessary ore reserves on the basis of equipment relibility characteristics, and thus helps to solve the ore reserves problem which is to define their optimum dimensions under conditions of stochasticity of production processes. In accordance with the tasks of the investigation it may be conventionally divided into three parts. The aim of the first part is to develop a structural open-pit system model consisting of a set of elements which are represented here by drill-rigs, shovels, trucks, unit trains, plant receiving bins and dumps (Fig. 1). The combination of similar elements makes up technological components the sequence of which forms simple systems. The latter, in their turn, grouping according to the type of mined rocks and inter- acting in parallel, form the "Stripping" and “Mining” subsystems. In addition to this, there is the "Ore Reserves" subsystem which serves as a "store" and includes opened-up, prepared and ready for extraction ore reserves.

Jan 1, 1977

By John L. Baum

GEOLOGISTS and engineers working around a diamond drill rig have often had the opportunity to observe the magnetic attraction of drill rods pulled out of the hole for core removal. This is sometimes an amusing pastime, but this same magnetic force inadvertently applied to a compass needle can cause it to lose its polarity entirely or to become reverse polarized when placed in the immediate vicinity of stacked rods. The first recommendation, of course, would be to avoid the rods, but in surveying an operating drillhole this is not always possible; therefore steps must be taken to neutralize the magnetic effect of the drill rods. Early in the summer of 1949 the geological department of the New Jersey Zinc Co. undertook at Franklin, N. J., an extensive program of surveying the course of deep diamond drillholes. The majority of the holes were surveyed while in the process of being drilled, and considerable difficulty was encountered. A pattern for the deviation of drillholes had been established for the district from surveys in holes from which the drill rig had been removed. It was observed that a certain operating deep drill- hole being surveyed did not fit this pattern. In the resulting confusion of repeated surveys and cementing a plug for wedging operations, the lower 1800 ft of the hole was lost. Because of this incident studies were initiated to determine the source of the difficulties and to develop safeguards against recurrence of faulty surveys.

Jan 12, 1954

By Leo Brewer, Gerd M. Rosenblatt

Thermodynamic calculations predict the species vaporizing from metal-oxide mixtures when reliable free energy functions, enthalpies of formation, and dissociation energies are available for the possible gaseous and condensed oxide components. Calculations of the oxygen to metal ratio in the vapor phase compared with the oxygen to metal ratio in a liquid metal saturated with oxide impurity are presented The possibility of purifying metals contaminated with oxide by vacuum melting or by distillation is discussed. Kinetic considerations affecting rates are neglected. IN recent years extensive information has been obtained on the thermodynamic stability of gaseous oxides of metals due to a variety of new types of measurement. Perhaps the greatest amount of information has come from the application of mass spec-trometry to the study of high-temperature vapors.' In many instances oxides of quite unusual oxidation states are found to be important in the high-temperature vapors. At low temperatures the standard free energy change for a reaction as given by the equation ?F° = ?H° - T?S° is determined primarily by the AH" value. However, at higher temperatures where the value of T in the T?S° term is large, the entropy term becomes equal to or greater than the AH term. At low temperatures only reactions for which AH is negative or only slightly endothermic are of importance. This restricts the main equilibrium species largely to those with completed octets or those with the principle oxidation number of the element. At

Jan 1, 1962

By J. S. Johnson, W. C. McCulloch

All phases of plant operation must be synchronized so that the A number of interruptions in the flow of material may be reduced to a minimum. In the majority of plants operating under a labor agreement, time lost during the operating shift cannot be made up with overtime. With the work week restricted to 35 hr., the ratio of productive time to total time justifies extra effort in keeping the plant operating at capacity during the productive shift. This does not apply when central plants with adequate storage are operated by multiple shifts. In such installations the problems become similar to those of any factory or mill where added units, parallel circuits, or excess capacity serve to maintain the average production during intervals of maintenance shut- down. These plants, by special agreement, may run continuously, barring mechanical interruptions. The control of plant operation is in those procedures that are practiced to obtain from the run-of-mine product a high recovery of clean coal products to meet adopted trade standards and consumer specifications at the lowest possible cost. Correlation of all factors for continuous operation requires more than mechanical perfection in the plant. The run-of-mine coal must be delivered to the preparation plant without delays and the clean coal and refuse products taken away. Power supply and water requirements must be adequate. Signal systems must be established for emergency stops and to facilitate resumption of coal flow.

Jan 1, 1943

By J. L. Thompson

Lime made in a coal-fired rotary kiln has two distinct parts: the interior of the pebble which constitutes about 90% to 95% of the mass, and the surface dust layer which is the remaining 5% to 10%. Uncalcined carbonate and impurities in the product may be present and will not contribute to the hydration reaction. Sulfur, in the form of calcium sulfate, inhibits the hydration reaction out of all proportion to its actual weigh- percent concentration (perhaps more than 100 times). If the stone contains dolomite, this will also inhibit the reaction as its rate of hydration may be nearly three orders of magnitude slower than that of calcium oxide. Early in the hydration reaction dolomite appears practically intert, but given sufficient time, it will hydrate. The heat of reaction is nearly the same as for calcium oxide, but the time necessary for complete hydration may be hours; whereas for calcium oxide it is only fractions of a second. The dust layer on the surface also inhibits hydration as it contains a collection of compounds which have low heats of hydration. This layer can tie up additional calcium and delay or prevent its reaction. In addition to these chemical processes, an important physical characteristic of the lime is its specific surface area. This is effected by the thermodynamics of calcination and the original stone grain chemistry. All of these factors are agglomerated in the gross slaking rate of lime.

Jan 1, 1980

By G. St. J. Perrott

AN explosive of, balanced composition might be expected, on first consideration, to develop maximum propulsive strength.1 This hypothesis is based on the assumption that an excess of oxygen would act simply as an inert material with a consequent lowering of flame temperature, also that a deficiency of oxygen would tend toward incomplete reaction of the combustible materials, thereby preventing development of the full strength of the explosion. Actually, however, it can be shown both theoretically and experimentally that an explosive having a certain oxygen deficiency will develop the greatest propulsive strength. This fact has been known to the technical staffs of explosives manufacturers for many years, but it has not always been recognized by explosives engineers in the field. For example: There: is a fairly widespread opinion that the wrapper of a stick of dynamite is merely a container for the explosive and that it plays little if any part in the development of propulsive strength. Actually, it can be shown that the wrapper enters fairly completely into, the explosive reaction. In the case of most gelatin dynamites, a given weight of explosive from which the wrappers have been removed will develop considerably less strength than the same weight of explosive plus wrapper, in spite of the fact that the latter combination contains less weight of the actual explosive ingredient. It can also be shown that a cartridge 7/8 in. in diameter may be stronger, weight for

Jan 1, 1928

By Walter W. Lilly, Issa S. Oweis

Application of rock engineering in geotechnial consulting practice considered herein is in areas of: (a) bedrock verification for foundation support, (b) bearing capacity and settlements, and (c) excavations. A routine geotechnical investigation usually provides data on depth to rock, rock classification, and rock quality. In cases of rock outcrop, such outcrops are mapped for geologic structures and rock mass description. In addition, the regional geology and the general aspects of the groundwater regime are usually known from either published literature or previous experience. The predominant technique for ground and site investigation are usually drilling and geologic reconnaissance. Other techniques involving seismic and geophysical soundings, borehole camera, and oriented cores are used by by no means routine. Performing laboratory strength and compressibility tests is often made to be considered as routine. The use of the point load test is gaining increasing use in the United States and would, perhaps, become a routine field or laboratory test due to its simplicity and, more importantly, its relatively low cost. The purpose of this paper is to describe cases where mostly routine investigation and testing were used to arrive at engineering decisions. Bearing Capacity and Settlements The allowable bearing values for foundation support on rock is usually dictated by local building codes which presumably should reflect local experience. The interpretation of the code, however, can present a problem, especially if the interpretation is made by a designer under the delusion of knowledge in rock engineering. For

Jan 1, 1982

By Fred P. Dewey

Although coke is the acknowledged metallurgical fuel, and has been extensively used in this country for more than thirty years, yet the facts on record in regard to its physical properties are exceedingly meagre; and this is also true, but in a less degree, of its chemical composition. An investigation is being carried on in the National Museum which is intended to supply, so far as may be, this deficiency, and through the kindness of Professor Baird, Director of the Museum, I am permitted to present to the Institute a summary of a portion of the results already obtained. So far as I am aware, the credit for the first systematic investigation of the physical properties of coke belongs to Mr. John Fulton, Mining Engineer of Cambria Iron Co. The results of this investigation have been published in Report L, Second Geological Survey, Pennsylvania, 1875, and in a pamphlet setting forth the advantages of the Connellsville coke, the latter published also by the " Virginias"* His results are not altogether free from experimental errors, and the assumption that "the specific gravities of coke and water are very nearly alike "- is scarcely warranted. It has seemed to me, therefore, desirable to make an independent investigation of the physical properties of coke on a plan somewhat different from that adopted by Mr. Fulton. This is the investigation now being carried on at the National Museum.

Jan 1, 1884

By R. Hogg, R. Schaller, P. Luckie

OVERVIEW This paper is a review of two fine particle processing unit operations - classification and mixing. It may appear that these two processes have nothing in common. In fact, the simplified symbols used to represent them on flowsheets - a tipped equilateral triangle such that the base lies along the vertical - are totally reversed. For classification, a splitting action, the apex of the tipped triangle is to the left of the vertical base. A horizontal flow arrow indicating input is drawn to the apex while two horizontal flow arrows indicating outputs are drawn from the top and bottom of the vertical base, respectively. On the other hand, for mixing, a blending action, the apex of the tipped triangle is to the right of the vertical base. Two horizontal flow arrows indicating inputs are drawn to the top and bottom of the vertical base, respectively, while a single horizontal flow arrow indicating output is drawn from the apex. Classification is the process whereby a collection of particles is separated into two or more portions differing in some physical or chemical property. Mixing is the process whereby two or more portions of particles differing in some physical or chemical property are combined into a collection of particles. The common bond that links them together in the same review is the fact that they both require dispersion of the particles in order to achieve successfully their individual objectives.

Jan 1, 1980

By Blamey Stevens

The object of this paper is to present a theory of the formation of fissures, which seems to be supported by all available data. The investigation is, in the main, an exact one, and irregularities of the rock-structure are generalized. From the conclusions drawn a general classification of fissures is made, and this should be of practical use in the comparison of mineral deposits. The theory also throws some light on the equilibrium of the earth's crust and the depth of action of surface-waters. Incidentally, additions are made to the theory of earthquake-slips. Former Theory. It has been previously pointed out that the "jointing" of homogeneous rocks occurs in two sets of planes, at right angles to one another, and making angles of 450 with the directions of greatest and least principal stress.' The theory by which this fact is explained does not, however, account for fissures and faults, because normal faults are usually more vertically, and reverse faults more horizontally, inclined than 450. The "jointing law" is based on the following axiom: In a homogeneous mass under pressure, rupture must take place on the lines of maximum tangential stress."2 This law applies, with fair approximation, to the tests on jointing which can be made in the laboratory, and as nearly as can be expected to the natural jointing-planes in rock-masses, where the stresses are not very great; but it entirely fails to account for fissure-fractures.3

Jan 1, 1910