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By C. W. Pollock

THAT a distressing explosion of some magnitude did not take place in the Berry No. 3 mine of the Ford Collieries Co. recently was solely because no source of ignition was present when the stage was set for such an occurrence. The mines of this company, which are in West Deer Township, Allegheny' County, Pa., have been operating in the double or thick Freeport seam since 1.909. During this entire period they have been classed as gaseous by the Pennsylvania Department of Mines, and some gas has been encountered from time to time almost entirely however in development work in the vicinity of clay veins or wants-and never to my knowledge on gobs or in rib work.

Jan 1, 1935

By James Marsh

INTRODUCTION Economists have long expressed suspicion of the economic theory of natural resource exhaustion, even in writing articles which have contributed to it (1). Indeed, the gap which separates the pure theory from practical management seems unusually wide. It is doubtful whether a mine manager could possibly know enough about the relevant parameters of his mine to steer it along the optimal paths described by the theorists (2). Nevertheless, enough faith in the theory remains that mine managers are suspected of being a separate breed whose behavior must be studied in special courses using specialized text-books, collections of readings, and journals (3). The implied hypothesis, that mines and natural resource firms are managed differently than other firms, is the subject of this paper. In the next section the theory is developed and analyzed. In section III, I discuss the implications of the statistical results that have been obtained. Finally, conclusions are reserved for section IV. THE MODEL A key difference between the traditional theory of natural resource production and that of other forms lies in the set of variables which ire assumed to jointly determine the quantity of output the firm will produce. Output, in the non-resource case, is assumed to be a function of k clearly definable and distinguishable inputs or factors of production, viz., y = f(xl, x2, ..., xk), (1) here

Jan 1, 1977

By René de Batz

From 1754 to the end of 1895 the production of gold in Russia had been approximately as follows: Kilogrammes. Russia proper (Finland and the Caucasus),. .. 890 The Ural Region,........505,386 Western Siberia,........116,937 Eastern Siberia,........1,218,372 Total,.........1,841,085 of the value of more than $1,200,000,000.

Jan 1, 1899

By G. E. Frantti

UNDER the auspices of the Geophysical Committee of Michigan College of Mining and Technology, an investigation was made in Michigan's Upper Peninsula to obtain geophysical data" related to the regional subsurface geology in the area covered by Paleozoic sediments. The area surveyed includes that portion of the Upper Peninsula which lies between R18W to R26W and T41N and T49N, covering approximately 1300 square miles. On the index map, Fig. 1, it is represented by the cross-hatched zone west of Munising. Four of the five sites of detailed investigation are indicated by the letters A, B, C, and D. A detailed gravity and magnetic survey had previously been conducted by J. G. Wilsonz near Perkins, 8 miles north of Rapid River, on a local anomalous area. Results of his work, which showed a large positive magnetic anomaly associated with a gravity anomaly, aroused interest in the possible economic significance of the formations underlying the Paleozoic sediments in this part of the Upper Peninsula. Early in the 1900's the Michigan Geological Survey, as well as many private companies, had done a considerable amount of dip needle work near the southwest corner of the area discussed in this paper. Most of the information available to the writer was obtained from indicated magnetic anomalies on the geological map of the northern peninsula of Michigan. Results of the geophysical activities of mining companies in the vicinity of the Marquette range and Gwinn district were unavailable to the author. Physiography and Geography: The region under consideration has low to moderate relief. About half the area is comprised of swampy lowlands, and because of the swamps and forests much of the land is almost inaccessible. The major drainage system is dendritic, with streams flowing into Lake Michigan on the south and Lake Superior on the north. The general geology, shown in Fig. 2, indicates an overlay of Paleozoic sediments on pre-Cambrian formations along a line running approximately south from Marquette (not shown on the geological map). Actual contact between pre-Cambrian and Paleozoic sediments is not known because most of the area is covered with glacial till, and outcrops are very scarce. Exposures of the Paleozoic sediments show that these beds in the northern areas dip gently under Lake Superior and that in the southern areas they 'dip gently to the southeast. Outcroppings of the pre-Cambrian formations occur primarily to the west of the surveyed area except in the northwest corner where the Laurentian series outcrop as far east as the Gwinn district and also in T46N, R24W. Instrumentation: Gravity measurements were made with the Worden portable gravity meter. Since this was chiefly a reconnaissance regional survey, both the large and small dials were used. The instrument used had a constant of 0.0035 milligals per scale division, a working range of about 25 milligals.

Jan 1, 1957

By R. E. Hobart

The development of the Hauto power plant and the claims made by various engineers that electricity was more economical than steam for power purposes in and about the mines, led the Lehigh Coal and Navigation Co., in 1911, to conduct a test to ascertain the consumption of power used by a large steam hoisting engine. The question being one on which no reliable information could be found, and the opinion of various engineers differing to such an extent, it was decided that a test under actual operating conditions was necessary. This was arranged for at one of the collieries. The engine selected was 2 30 by 60-in. (76.2 by 152.4-cm.) piston-valve engine of modern type, and comparatively new. The boiler plant from which the hoist received its power was about 600 ft. (182 m.) from the engine, the latter being fed by a 10-in. (25.4-cm.) steam line insulated with magnesia pipe covering. Two batteries of the boiler plant, aggregating 1200 hp., were cut off and fed into a separate steam line leading direct to the hoist engine. Steam auxiliaries, consisting of feed-water pump and blowers, were fed by the boilers in test, and their consumption charged against the hoist. A barrel weighing device was installed, as it was felt that this would be the most accurate way of determining the consumption of water. The fuel, No. 3 buckwheat, was carefully weighed, and every precaution was taken to make the test accurate in every particular. The test was run for 1 week, or a total of 168 hr. A record was kept of the number of trips hoisted or lowered, and continuous indicator cards were taken. One particular set of cards was taken with the hoist operating balanced, and also with the hoist operating with no counterweight other than the empty cage, the coal in the car being weighed. The speed of the hoist was taken by means of a graphic recording instrument which registered the number of revolutions every 5 sec. From this record, speed-time curves were plotted.

Jan 1, 1918

By R. E. Hobart

THE development of the Hauto power plant and the claims made by various engineers that electricity was more economical than steam for power purposes in and about the mines; led the Lehigh Coal and Navigation Co., in 1911, to conduct a test to ascertain the consumption of power used by a large steam hoisting engine. The question being one on which no reliable information could be found, and the opinion of various engineers differing to such an extent, it was decided that a test under actual operating conditions was necessary. This was arranged for at one of the collieries. The engine selected was a 30 by 60-in. (76.2 by 152.4-cm.) piston-valve engine of modern type, and comparatively new. The boiler plant from which the hoist received its power was about 600 ft. (182 m.) from the engine, the latter being fed by a 10-in. (25.4-cm.) steam line insulated with magnesia pipe covering. Two batteries of the boiler plant, aggregating 1200 hp., were cut off and fed into a separate steam line leading direct to the hoist engine. Steam auxiliaries, consisting of feed-water pump and blowers, were fed by the boilers in test, and their consumption charged against the hoist. A barrel weighing device was installed, as it was felt that this would be the most accurate way of determining the consumption of water. The fuel, No. 3 buckwheat, was carefully weighed, and every precaution was taken to make the test accurate in every particular. The test was run for 1 week, or a total of 168 hr. A record was kept of the number of trips hoisted or lowered, and continuous indicator cards were taken. One particular set of cards was taken with the hoist operating balanced, and also with the hoist operating with no counterweight other than the empty cage, the coal in the car being weighed. The speed of the hoist was taken by means, of a graphic recording instrument which registered the number of revolutions every 5 sec. From this record, speed-time curves were plotted.

Jan 2, 1918

By Fuller, T. S.

THE number of rare or uncommon elements in use in the electrical industry nowadays is large, their application having come about through investigational work in industrial search laboratories and ' educational institutions. Such elements, together with those whose properties are more generally known, constitute Nature's gift to mankind and make possible the intricate devices which further our modern civilization. The' quality of raiaity is one of degree, and obviously depends largely on one's point of view. From the standpoint of quantity measured in the customary units of weight and volume, the amounts of many of the elements required are extremely small, but from the of view of performing some particular function or .other in a manner more satisfactory or cheaply than can be accomplished by any other sub- stance, the use in question may be extremely important.

Jan 1, 1928

By Bob J. Rawicki

TYPES OF WET DUST COLLECTORS Basically, there are two types of wettype dust collectors. One is mechanical, incorporating pumps, motors, fans, sprays, filters, or flooded beds. These come in many forms, but their operating principle is basically the same. The screen or flooded bed is wetted by a series of sprays. Polluted air is drawn in through a fan; here the dust particles impinge on the screen and are flushed off into a settlement tank. The air then passes through spray eliminators to the atmosphere. A great deal of time and money has been spent developing this type of collector. In laboratory tests where clean water at constant pressure, air at constant volume, and dust at low but constant mass to volume were applied, these collectors gave high percentage dust collection efficiencies. Theoretically and technically, they are very good. In practice, however, under rugged mining conditions where there are no constants, and dust load, particle size, water pressure, and volume of air vary with time, their efficiency varies dramatically. Some of the most common problems are: 1. clogging of screens 2. blocking of nozzles 3. replacement. of damaged pump stators Any of the above result in loss of air flow and dust collection efficiency. Generally, there are so many mechanical moving parts, something is always breaking down. This type of collector is very expensive in parts and labor to maintain. The second type of dust collector, which I personally developed, with the help of the British National Coal Board of Great Britain, has none of the above mentioned problems and it works on a completely different principle. My collector, the Mark III Precipitaire Wet-Type Dust Collector, (an improved version of previously successful models) has no internal moving parts, no flooded beds, screens, spray nozzles, etc. It is highly efficient - 99.8% efficiency on total collected dust and 97% on respirable dust. The pressure drop through the collector is constant, hence, air flow remains constant. There is no maintenance expenditure, be it labor or parts. The only maintenance that there is, is desludging. This, of course, varies with the dust load. With a low dust load, desludqinq may only be required every 4 weeks, but this is a very simple operation that can be handled by unskilled men and it takes only a very short time. My collector is powered by a ventilation fan that is placed on the clean air side for a longer fan and motor life. Dust is extracted solely by water action. The collector's operating principle is: Dust laden air is drawn in along ducting into a tapered scrubber section, shaped to create a self-induced curtain of water. This action washes the dust particles from the air and the collected dust settles into the bottom of the tank. Cleaned air is then exhausted via a series of spray eliminators where it is completely dried and on into the atmosphere. These collectors have been sold in Great Britain, to the National Coal Board, and throughout Europe. They have been working very well for many years now. GENERAL APPLICATIONS Dust is very dangerous; silicosis and black lung kill and disable many workers each year. Many of the mine explosions can be attributed to coal dust. By the use and application of dust collectors, these deaths and disasters can be avoided. There really is no excuse. However good and efficient a dust collector may be, it's positioning and installation arrangement is critical. The collector may remove 99% of dust supplied to it, but it takes the skill and experience of a dust control engineer to design and fit ducting, hoods, etc. to remove polluted air at source and deliver it to the collector. In some cases this is very simple; in the case of longwall machines, it is very difficult. In general, dust collectors should be used to collect dust at every point of dust generation. I have noted a great reliance on dilution as a means of dust control. I personally think this is a dangerous and unreliable method. As mines become deeper and the use of larger and more productive equipment becomes more common, reliance on dilution will be impossible and dust collectors will be essential.

Jan 1, 1982

By Chris Weyand

Throughout the past 40 years we have been drawing inevitably closer to the conclusion that coal will be our chief source of energy. Our reserves of natural gas and petroleum, on which we depend, are dwindling. Knowing that we will soon reach our physically extractable limit of these energy sources. The US government has created many incentives to encourage energy companies to transfer technology and resources from natural gas and petroleum to coal. Such encouragement is stimulated through taxation methods. Coal mining engineers deal mainly with production, which involves planning and design throughout the acquisition, exploration, development, production, and reclamation of a mine. Though taxation is not one of the areas analyzed by the engineer, it should be considered and understood as it is involved in the mine life cycle. This paper will discuss coal taxation in the five stages of mining and will explore certain tax saving decisions.

Jan 1, 1983

By E. F. Burch, R. W. Schoenberger

This paper deals with an investigation of the use of steam filtration for filter cake dewatering and shows that it may be applied on a practical scale. The advent of larger quantities of minus 1/4 in. coal in the raw feed to the preparation plant and the necessity of recovering this material has made the problem of meeting product moisture specifications more difficult. For a number of years thermal dryers have been used advantageously as a means of reducing fine coal moisture content where the over-all economics would justify such an installation. However, these units are not without their drawbacks because of high capital and operating costs, safety hazards and possible degradation of the product, and thus an alternative method of moisture reduction is highly desirable. After the various mechanical variables associated with filtration have been optimized, an examination of theory shows that surface tension and liquid viscosity are the only two remaining variables which might be altered to reduce moisture content. A lowering of the surface tension within the limits of normal wetting agent dosage results in a rather insignificant decrease in cake moisture content. Not until the dosage is increased to a point well beyond this limit is there an appreciable decrease in moisture. At these high dosage levels, interfacial tension is a major factor contributing to the appreciable moisture reduction obtained. Since no suitable method has been developed to recover and recycle this wetting agent, this phenomena is not of practical significance. On the other hand, a reduction in liquid viscosity has a pronounced effect on cake moisture. While it is readily apparent that one method of reducing liquid viscosity is to heat the entire feed slurry, it is equally apparent that this would not be an economic approach except, perhaps, in certain isolated cases. It does, however, suggest that water circuits should be designed to conserve heat as much as possible and to make use of any waste heat that may be available. The use of hot air as a heat carrying medium for drying porous materials on a filter has been practiced for many years. However, this method is restricted to materials with a high air rate in the order of 100 cfm/ ft2 because of the low heat release per unit weight of air passing through the cake. The normal fine coal filter cake has an air porosity far too low to make this a practical approach. Various types of radiant heating devices have been investigated and can significantly lower moisture content at reasonable thermal efficiency. However,

Jan 1, 1964

By W. C. Phalen

The production of salt in the United States divides itself at the outset into two distinct classes…

Jan 1, 1915

By WILKES BARRE

AS PREVIOUSLY announced, the semi-centennial meeting of the Institute is to be held at Wilkes-Barre, Pa., on Sept. 12, 13, 14, and 15. An interesting program of technical sessions and excursions is now being prepared by the Local Committee. At the time of going to press the program had not been completed in sufficient detail to permit its being pub¬lished in this number. The detailed program will be published in the September MINING AND METALLURGY, which will be printed in time to be distributed before the Wilkes-Barre Meeting. It may be said in advance, however, that the Com¬mittee has progressed so far in its work that we are assured of one of the -most notable meetings the Insti¬tute has held and that members will miss a rare .treat if they do not attend. The many trips and excursions, as well as the banquet, will be -given to the members as a compliment from the members of the Local Com¬mittee. . . The paper by Howard Eavenson on the Lynch Plant of -the United States Coal and Coke Co. will be illustrated by lantern slides and moving pictures. One of the most appropriate discussions will be that opened by Prof. J. F. Kemp on the Stratigraphy of the Anthracite Region; this also will be amply illustrated.

Jan 1, 1921

By Michael S. Roscoe

In order to more accurately predict longwall surface subsidence over the Pittsburgh No. 8 Coal in Eastern Ohio, North American Coal Corporation's Quarto Mining Company undertook or participated in several subsidence studies. Due to the changing roof geology and rapid variations in the amount of cover two separate areas were investigated at two different mines to determine the subsidence response if any to these changes. Data generated from these studies were compared with NCB derived,data for accuracy and then used to predict subsidence under houses, gas lines and other critical man made structures. The following report summarizes the results of these studies as well as the subsidence case histories of gas lines, transmission towers, houses and water wells. Problems that were encountered during both phases of this process (investigation and subsequent application) are also included.

By Tell Ertl, Will Mitchell

THE Mineral Industry Education Division made the headlines when Columbia's President, Nicholas Murray Butler, welcomed it in a provocative address made before a record crowd of over 100 members attending the opening Sunday session in the Columbia Men's Faculty Club. Arthur F. Greaves- Walker, Chairman of the Division, who was presented by H. R. Hanley, told of the excellent job of war research being carried on in the colleges. E. A. Holbrook led a discussion on the unionization of engineers, stating that he had learned that professional engineers were being forced into unions by subprofessionals. This might become a serious problem if the professional engineering organizations are lax in combating the

Jan 1, 1944

By John Freeman

THE tensile properties of steels at elevated temperatures have been studied by numerous investigators,1 primarily for the purpose of determining their suitability for structural uses. Tests with this objective have been confined largely to the temperature range of approximately 20° to 500° C., because of the rapidly decreasing tensile strength at the latter temperature. Tests have also been extended to higher temperatures for the purpose of determining the most suitable forging range. This temperature range is also of theoretical interest. The phenomenon of increased tensile strength and decreased ductility in the so-called "blue-heat" range, approximately 200° to 300° C., is well known. It was suggested to the Bureau early in 1926 that a study of the properties of rail steels in this temperature range might prove of interest in relation to the studies of transverse-fissure failures in rails. There were available from another investigation3 several new rails from several different heats made to approximately the same specification requirements, the complete manufacturing histories of which were known. It was decided to determine, at least in the preliminary series of tests, only the ultimate tensile strength, elongation and reduction of area, because of the difficulty, time and cost involved in determining the proportional limit and yield point at elevated temperatures.

Jan 1, 1930

By A. N. Mitinsky

(San Francisco Meeting, September, 1915) THE theory of elasticity, the science of the strength of materials, and all our calculations regarding engineering structures are based on Hooke's law, that in loaded bodies the deformations are, proportional to the load producing them. Without this law it would be impossible to design intelligently engineering structures such as bridges, frames, axles, etc. This being the case, the proportional limit,1 that is, the point at which deformation ceases to be proportional to load, is the most important factor in engineering design. Further, the working fiber stress should be fixed in reference to the proportional limit instead of, as is usual, in reference to the ultimate strength. The incorrect use of the ultimate strength instead of the proportional limit in setting the working fiber stress is probably clue to two reasons: (1) it is a more delicate operation to measure the proportional limit; (2) it is usually -assumed, though incorrectly, that the proportional limit is determined by the ultimate -strength. In Germany the point at which permanent set first appears is often taken instead of the proportional limit. The two points will coincide if Gerstner's law, that elastic deformations are proportional to the loads producing them both before and after permanent set, is true; and the limit of proportionality and the elastic limit or point of permanent set will both 'be represented on a stress-strain diagram, by the point at which the line ceases to be a straight line and becomes curved-or changes its inclination. It is to be further noted that the difference in definition between proportional limit and elastic limit introduces a difference in methods of determination in the testing laboratory. The German method of determining. the elastic limit by alternately loading and unloading

Jan 8, 1915

By John L. Schroder

The demands for increased productivity on the 1967 coal industry have generated new operating trends and fresh approaches to old methods, which have enabled the industry to keep pace with the expanding economy. Changes, while not radical in concept or design, have been plentiful and are marked by the refinement of the already tried, tested and proven. Perhaps not since World War II have there been demands on equipment manufacturers to design and deliver such diversified types of machines as those required by the industry in the past year. Equipment developments-following a plan which calls for higher productivity, lower maintenance costs and greater machine availability- have tended more toward increased horsepower and heavier, more rugged equipment. Electrical and mechanical components, designed in many instances with maximum reliability rather than initial costs as the main criterion, have contributed to the improvements in over-all performance. High-strength, specialty steels are finding use in a wide range of equipment applications. The horsepower capacity of electric motors being installed is more frequently being rated on a continuous basis rather than the former one hr or less and, as a result, fewer failures now occur because of overloading. These developments reflect the pyramiding cost of equipment down-time and represent definitive progress in reducing the magnitude of the problem.

Jan 2, 1968

By R. E. Wagner

MISSOURI's famous lead area, in what is known as Southeast Missouri, is locally termed the "Lead Belt." These deposits are in the Bonne Terre dolomite of late Cambrian age which has a thickness of nearly 400 ft. Underlying this is the La Motte sandstone which varies in thickness from 0 to 400 ft. The La Motte beds are deposited directly on the ancient erosion surface of Pre-Cambrian porphyries and granites of probably Algonkian age. The buried igneous peaks extend up into the Bonne Terre in several areas within the Lead Belt. Overlying the Bonne Terre are shales and siliceous dolomites of late Cambrian and early Ordovician age. Within the Lead Belt these have a thickness of from 0 to 500 ft. The district is bounded in general on the southwest by the Sims Mountain fault, on the northwest and north by the Big River fault, and on the

Jan 1, 1947

By Russell B. Cornell, William B. Plank

AT the close of the academic year 1940-'41 the largest number of students ever recorded received their first or bachelor degree in the mineral technology schools of the United States. The total of men thus prepared to enter their professional careers in the mineral industries was 1601, a number nearly 12 per cent larger than two years ago and nearly 75 per cent larger than four years ago. Notwithstanding this increase in the number of graduates and as had been predicted in the preliminary report in February, there was a slight decrease in the total student population of the schools in both the United States and Canada. During the college year 1940-'41, 9133 students were enrolled in the 54 schools of the United States and 764 in six of the seven schools of Canada.

Jan 1, 1941

By C. S. Herzig

Some time ago, in Mexico, our signal-bells in a 700-foot shaft caused us considerable annoyance by continually getting out of order, each time so delaying our hoisting operations that we naturally desired to remedy this evil. There were two mays open: either to patch up the old bell, which was of the ordinary pattern, every time it failed to work, or else to devise some new arrangement.. On consultation with our foreman we designed a signal-device which, during the number of months I watched its operation, worked satisfactorily, without once getting out of order. We sought to produce a simple device, in which no greater pull on the lever would be necessary from one level than from another; to counterbalance independently the weight of the pendant bell-rope, so that there would be no direct weight on the working-parts of the bell itself, and likewise to arrange it so as to necessitate only a light pull on the lever in signaling; and, finally, to make some sort of trip-arrangement, so that whenever the signaling-lever underground passed through a certain arc the signal would be given in the engine-room. By this means we wished to obviate the ill effects of sudden heavy pulls and rough usage in general, such as all signaling

Jan 1, 1901