Search Documents

By E. A. Swedenborg, J. S. Ross

Oil-field waters enter into many underground problems with which the petroleum engineer has to deal. Whether the problem is one of infiltration or natural encroachment, it is always desirable to determine the source of the water before commencing repair or remedial work. The usual mechanical tests for determining the source of extraneous water in wells are slow and expensive. An excellent means for the identification of oil-field waters may be afforded by their chemical characteristics when the chemical character of waters from the various sands has been established by careful sampling and analysis cautiously interpreted. In the Salt Creck field, Wyoming, a fairly high degree of efficiency has been attained in the control of field operations by utilizing the information afforded by the analysis. All of the operating companies appreciate this means of identifying waters, with the result that water-sampling has become general practice. Most of the chemical work dealing with Salt Creek waters has been done since the laboratories of the Midwest Refining Co. and the U. S. Geological Survey, were established in the field; the former in 1922, the latter in 1924. A spirit of cooperation has existed between the company and the government personnel by which many of the data for this paper were made available. Sands of the Salt Creek Field The principal sand horizons in the Salt Creek field are the Shannon, First, Second, and Third Wall Creeks, Dakota, Lakota, Sundance and Tensleep. Of these the important oil producers are the First Wall Creek, Second Wall Creek, Lakota and the Sundance. The Third Wall Creek is lenticular and is productive in only a few wells in the southern end of the field. There are also a number of shale wells, but they do not produce water in any appreciable amount. The stratigraphic position of these sands and their relative thicknesses are shown on the condensed composite section of Salt Creek

Jan 1, 1929

By G. St. J. Perrott

ONE of the important hazards in coal mining is the danger of ignition of explosive mixtures of methane and air or coal dust and air, or both, by the explosives used in blasting the coal. It has long been recognized that certain explosives are more dangerous than others in this respect. In America and abroad, government testing stations have been established for officially passing on the suitability of explosives for use in coal mines. In this country the Federal government is given no power to enforce the use of the approved explosives but merely publishes from time to time, through the Bureau of Mines, those explosives which have passed the tests necessary to place them on the list for use in coal mines. In spite of this lack of police power, the increase in the use of permissible explosives since the promulgation of the first list in 1909 has been rapid. In 1912, only 8 per cent. of the explosives used in coal mines were permissible; in 1925, this figure had increased to 25 per cent. While the past record of permissible explosives has been most gratifying, it is very desirable that we pave the way for further improvement in explosives and blasting methods by learning more about the mechanism of ignition of gas and coal dust by explosives. To this end a considerable amount of investigative work already has been carried out and a large amount yet remains to be done. It is the purpose of this paper to discuss briefly the effect of the characteristics of explosives and method of loading in the borehole on the liability of a blown-out shot to ignite explosive mixtures of gas or dust. For an account of the methods by which an explosive is tested for permissibility for use in coal mines, the reader is referred to Schedule 17-A of the U. S. Bureau of Mines.

Jan 10, 1926

By Edward W. Parker

At the Cleveland meeting of the Institute, October, 1912, I had occasion to call attention to the general though erroneous impression that the principal mining activities of the United States lie west of the 100th meridian of longitude. Few, I believe, realize that the States east of the Mississippi river, which comprise only 28.8 per cent. of the total area of the United States, exclusive of Alaska, contribute about two-thirds of the total mineral production, computing by values. In 1910 the percentage of the production credited to the Eastern States was 67; in 1911 it was 65. When I have, with becoming modesty, ventured to speak of these comparisons, I have usually been met with the rejoinder, " But you include coal." I surely do, for whereas coal (m petroleum, as natural gas, as limestone) is not in the strictly technical definition of the word, a " mineral," it is legally mineral, is certainly a mineral substance, and contributes by far the largest tonnage and approximately one-third of the total value of all mineral products. The production of coal-mines in 1911 weighed approximately 500,000,000 tons. In 1912 it exceeded that record by nearly, if not quite, 50,000,000 tons. According to H. D. McCaskey, of the U. S. Geological Survey, the total weight of all the metallic ores mined in the United States in 1911 was 105,000,000 tons (a little more than one-fifth that of coal). In 1910 Mr. Lindgren estimated the total weight of all metallic ores at 120,000,000 tons. The products of the quarries, clay-pits, oil-wells, phosphate-mines, and other non-metallic products, taken all together, did not in 1911 weigh in excess of 300,000,000 tons, so that the output of coal exceeds by 25 per cent. the combined tonnage of all other mineral products. The coal-mines give to

Jan 1, 1914

Last November, when the British Educational Mission was visiting this country, letters were sent to the various mining schools asking what arrangements had been made for cooperating with British and. French schools. Of the eleven schools from which replies were received, none had taken any definite steps in this direction. The Colorado School of Mines, though, stated that it was offering scholarships to all men who had served in the U. S. Army and Navy during the war. A letter was also sent to Sir Henry Miers, Vice-chancellor of the University of Manchester, who was the head of the British Mission. He replied as follows: "In my opinion the mining profession is second to none in the responsibility of the duties which it involves or to which it leads in all parts of the world; also it is a. profession in which the student or teacher has much to gain by migrating to foreign countries. This applies in a special degree to British students coming to America where they will be able to enlarge their views by a widened experience. We (the Mission) have everywhere found the most, cordial acceptance of such proposals. Several of the British Universities have recently instituted a new doctorate of philosophy attainable after 2 or 3 years course of advanced study; this scheme includes Oxford and Manchester. The conditions admitting to the degree course are that the applicant should be a graduate of an approved University and should show evidence that he is qualified to pursue the course which lie proposes." In a conversation with Prof. Alfred C. Lane, of Tufts College, Sir Henry Miers said that students from Great Britain should be most easily attracted to America, both to universities and colleges and technological institutions.. He doubts, however, whether Great Britain can offer America, in this respect, as much as America can offer her. Prof. Lane, though, is quite sure that, especially for geologists, there is much to be

Jan 2, 1919

BURKE BAKER, Philadelphia, Pa. (written discussion*).-The small briquetting plant of the American Briquet Co., at 25th Street and Washington Ave., Philadelphia, was built primarily as a demonstration plant. Its output per hour is 4 tons of 2-oz. briquets, which have been retailed in the, vicinity during the year the plant has been in operation. They have proved very acceptable for use in ranges, heaters and grates in-home, and in steam heating plants in apartment houses and hotels. They have not been sold for power purposes, although satisfactory tests have been made in. this field. Anthracite silt is used and is shipped direct from breaker or washery, the only preparation it receives being the removal f excess moisture by means of a Ruggles-Coles rotary dryer. Care is taken, however, to purchase silt containing less than 18 per cent. ash. The method is covered by U. S. Patent No. 941454, issued to Chas. E. Hite, and is known as the "emulsion process." The binder, which is the, basis of the patent, is composed. of 0.5 per cent. cornstarch or wheat flour; 1 per cent. asphaltum or hydrolene, and 6.5 per cent. water, on the weight of coal dust. It is prepared in a tank equipped with paddle agitators and heated by steam jets. The starch and water are first made into a paste by being brought to the boiling point with live steam; the melted asphaltum is then introduced and thoroughly beaten into the paste by the agitators. This rapid stirring breaks. the hot asphaltum into minute particles which are distributed through the paste, producing a smooth chemical emulsion. This emulsion, when dried, is not soluble in water. The binder is mixed with the dry coal dust in a horizontal paddle mixer, 8 per cent. binder to the weight of coal being used. The resultant plastic mass is then discharged into the press, which is of the simple roll type. Since the binder is a liquid and is not sticky or gummy until

Jan 3, 1918

By H. Case Willcox

AERIAL photographic surveying and mapping is not new or unknown to geologists. However, it has been utilized but little before, principally because it is only within the last few months that practical means of adapting this method to the requirements of petroleum companies have been discovered. No American aerial survey company has taken up aerial surveying and mapping as an engineering service to be offered to petroleum companies and their geologists for use in undeveloped and jungle-covered petroleum areas. This method of surveying and mapping, however, is used by the War Department, the U. S. Reclamation Service, and Geological Survey, and the corresponding Departments of the Canadian Government. ADVANTAGES OF AERIAL PHOTOGRAPHIC SURVEYING AND MAPPING The advantages of aerial photographic surveying and mapping to petroleum companies and their geologists are many. One of the most valuable is presented in the very first phase, or the exploration period. It is assumed that, when convinced that petroleum possibilities are present, a petroleum company has secured a concession of 8000 sq. mi. of unexplored area in Eastern Venezuela. The company may either have the entire area surveyed and mapped by the aerial photographic method, or send its chief field geologist up in an airplane so that he, from-an aerial reconnaissance, may reject certain portions that, for geological reasons, the company would not be interested in. He will then point out the regions that are to be surveyed and mapped. After the air-work is completed, the results are brought down, developed, and printed; then the resulting "contact prints" are given to the field geologist. They may be roughly assembled to give a general idea of the property in its entirety, or they are in shape to be examined in adjoining pairs under the stereo-scope. With this instrument, the geologist is enabled to make a minute examination of surface indications. The work of assembling and constructing a complete general or detailed map, according to the scales desired by the petroleum company and for the later office use, is continued by the aerial photographic company.

Jan 3, 1925

By Fred H. Lippold, Wm. H. Wolf

Methods of fair payment for excavating, supporting, and concrete lining tunnels have been sought by various owners for years. Tunneling techniques have changed with the development of equipment-from the hand-mucking operation to the machine mucker and, most recently, to machine-boring; from tunnel supports using timber sets to steel sets to rock bolts and, most recently, to shotcrete support; and from hand-placing the concrete lining using wooden forms to pumping or pneumatic placing using steel forms. As tunnel construction techniques advanced, so did methods for payment for the work performed. The recent development of tunnel-boring machines, or "moles," is precipitating another change. These changes have led to some difficulty in providing proper payment for the various items of work for different types of tunnels. As a major construction agency engaged in water-resources development in the western states, the U.S. Bureau of Reclamation has long been aware of the need for clarification of payment provisions in tunnel construction. The Bureau has some 150 miles of tunnels completed on its projects and about 50 miles of tunnels under construction. In this construction, the Bureau has benefited by the advance made by contractors in improving the techniques of tunnel excavation. To assure that the Bureau has an up-to-date approach to payment provisions, the Chief Engineer recently established a "standard" method of payment for all types of tunnels. It is believed that this new method of payment will be equitable for all contractors bidding on various types of tunnels using the diversity of methods of excavation now available to them. These payment provisions provide for different quantities for excavated tunnels using the blasting technique or using machine-boring techniques. In this way, the contractors have a choice in excavation methods and an equal opportunity to be low in their bids. We believe this will be an incentive to all contractors to be as progressive as the development of new equipment economically allows.

Jan 1, 1970

The following is an incomplete list of members and guests who called at Institute headquarters during the period Sept. 10, 1919, to Oct. 10, 1919. L. D. Anderson, Salt Lake City, Utah. P. S. Matthews, Newark, N. J. Ray J. Barber, New York City. A. Poole Maynard, Atlanta, Georgia. L. A. Barton, Major U. S. Engineers. L. J. Mayreis, Jamshedpur, India. J. A. Battle, Chicago, 111. Benj. L. Miller, Bethlehem, Pa. R. W. Bissell, New York City. Geo. D. Morgan, Bartlesville, Okla. Gilman E. Brown, Shanghai, China. A. C. Munroe, El Paso, Texas. Stanley Brown, Chuquicamata, Chile, Paul I. Norton, Jr., Columbus, Ohio. S. A. Walter G. Perkins, Stanford University, Norman Carmichael, Clifton, Arizona. Cal. Richard H. Catlett, Newark, N. J. Fred S. Porter, Seattle, Wash. Roderic Crandall Charles E. Prior, Cherry Creek, Nevada John J. Croston, Atlanta, Georgia. G. M. Richards I. N. Dally, Seattle, Wash. Gilbert Rigg, Melbourne, Australia. A. Faison Dixon, New York City. Pierre H. Sauvajol, Paris, France. Walter Dobbins, Springfield, Ill. Carl Scholz, Chicago, Ill. Foss E. Douglass, Rancagua, Chile. Ellsworth H. Shriver, Marysville, Ohio. H. S. Emlaw, Grand Haven, Mich. Harvey B. Small, Magangue, Colombia. R. S. Everet, Barre, Mass. Henry B. Smith, New Britain, Coma. H. W. Gipp, Melbourne, Australia. J. T. Smoody, Cornwall, Pa. F. A. Glass, Brainerd, Minn. S.. J. Speak, London, England. C. D. Grier, New York City. D. R. Thomas, New York City. James L. Head, Rancagua, Chile. Kirby Thomas, New York City. Geo. B. Holderer, New York City. R. M. F. Townsend, Washington, D. C. W. Spencer Hutchinson, Boston, Mass. Carl J. Trauerman, Helena, Mont. Henry Jequier, Paris, France. A. C. Veatch, London, Eng. L. W. Kemp, Chuquicamata, Chile. Myron R. Walker, Pittsburg, Pa. Herbert S. Kohlberg, El Paso, Texas. Curtis C. Webb, New York City. H. M. LaFollette, La Follette, Tenn. James Wilding, San Francisco, Cal. Richard Lamb, New York City. S. H. Zimmerman, New York City.

Jan 11, 1919

By S. J. McCarroll

J. Bruce Clemmer, J. B. Rosenbaum, and C. H. Schack (U.S. Bureau of Mines, Salt Lake City)—We have watched with considerable interest Three Kids development of Manganese Inc. and have been impressed by the ingenuity with which management and staff have solved their many obstinate handling problems. Mr. McCarroll has been lenient in describing the difficulties faced by the company in developing a process for beneficiating Three Kids ore. The operation, equivalent in size to a 20,000-ton sulphide ore plant, is treating a unique ore by a flotation process pioneered by Manganese Inc. Perhaps the magnitude of the conditioning and flotation problems peculiar to Three Kids ore can be better appraised when it is pointed out that two-thirds to three-fourths of the ore is floated in the rougher step and that the four stages of cleaning which follow are equivalent to floating the whole plant feed two to three times. Our experience in both laboratory and pilot plant flotation of Three Kids and other manganese ores leads us to agree with Mr. McCarroll that suitable conditioning is a prime requisite for successful oil-emulsion flotation. The difficulties of proper conditioning were demonstrated in pilot plant processing of Artillery Peak manganese ore at our Boulder City, Nev., experiment station. Over three months of experiments and extensive plant revision were required before satisfactory conditioning was obtained in the 25-ton-per-day plant. Such factors as time, type and intensity of mixing, aeration, surface to volume relationship, and power input are still being studied by the Bureau of Mines in hopes of learning how best to condition manganese pulps for oil-emulsion flotation. Other factors affecting flotation of manganese with oil emulsion also deserve attention. A few of these are the influence of stability and proportion of ingredients in the collector emulsion, the feasibility of grinding

Jan 1, 1955

By James Quigley

As the outcrop mines in the West developed into underground operations, systems of ground sup- port were gradually evolved. In the early coal mines there was little need for support except near the dirt line in portals, where stone masonry was common. Where the top was shaley or broken, native pine props with light cross bars and legs furnished enough support even in Utah's 25-ft coal seams. As depth of workings increased, roofs and backs of the same general nature as those near the surface became more and more unstable and required more and more support. Some coal airways show this tendency very clearly. From the surface down the same type of roof shows deterioration which an experienced eye can translate into a measure of depth under surface rather than change in rock characteristics. Rock bolts, developed by various companies and by the U. S. Bureau of Mines, have become an effective substitute for timber in sections of some metal and nonmetal mines formerly requiring excessive timber support, and further use of war surplus landing mats, chain link fencing, and a new punched channel developed by one of the steel companies has enabled other mines to operate deposits where costs of timber and lack of clearance for timber support would have prohibited mining. The block caving mines have made extensive use of reinforced concrete underground to achieve similar ends under difficult conditions. Steel sets are standard in many Bureau of Reclamation projects, although these are usually covered in with concrete to make the permanent structures the Bureau's reclamation projects require. But the use of steel in mining operations is limited and has been confined principally to the iron ore mines of Michigan, Wisconsin, and Minnesota. Some mines have installed used rail as posts, caps, and crossbars, but a rail section is not suited for load carrying, and used rails are generally brittle, having a tendency to fail without warning when overloaded.

Jan 7, 1959

By A. M. Starfield

The study of strain waves in rock over the past decade has, for the most part, been an investigation related, but not applied, to rock blasting; the design of rock blasts has proceeded on a basis that is independent of strain wave research. This duality is reflected in the paper by Dr. Clark.1 While the greater part of the paper is devoted to a discussion of spherical waves in elastic and visco-elastic media, it is in an entirely unrelated section, the section on scaling and cratering, that the practical approach to rock blasting is found. Work done by the U. S. Bureau of Mines, as described in the paper by Duvall, Atchison, and Fogelson,2 has established a correlation between crater dimensions and the peak compressive strain in the rock. Strain wave measurements have thus been used to compare explosives but have not, as yet, been applied to the planning of a production round once an explosive has been selected. The optimum burden, for instance, is still determined either by experience, empirical formulae (e.g. that of Langefors 3), or a cratering experiment and the theory that has been developed around that proposed by Livingston.4 Even then there is some ambiguity in applying deductions from short, concentrated explosive charges to the long charges often used in practice (although Bauer 5 reports doing this with considerable success) and wave theory has until recently thrown no light on this problem, being confined, with only a few exceptions, to spherical charges. The hesitation in applying strain wave theory has probably been due to two questions that have not been answered satisfactorily: just how important is the strain wave in rock breakage, and if it is important, under what conditions will the wave break rock? This paper is an attempt to answer the first question, to avoid the second question by an admittedly oversimplified assumption, and then to investigate the implications of this assumption for blasting with long cylindrical charges.

Jan 1, 1967

By Wilbert McBride

Two Alco 3 ½ -ton motor trucks were used by Young Bros. while operating at the Mammoth Collins mine at Shultz, Ariz. One was equipped with an oil tank holding 1,075 gal. and was used for the transportation of "tops." The, other was fitted with a stake body and used to carry machinery, wood, rails, pipe and all classes of miscellaneous supplies. The bodies were made of oak with maple flooring and were attached to the frame of the chassis by U-bolts, to avoid drilling the main members of the frame. Most of the hauling was done from Tucson, a distance of 47;2 miles. During the first. 3 months, part of the road was in very bad condition and the tire cost was excessive. After this part was repaired the road was in fair condition, but never good. There were no excessive grades or bad sand, but wagon ruts, too narrow for the truck wheels and of a different gage, caused heavy tire loss; while chuck holes, sharp curves and stones, both imbedded and loose, were objectionable features. During wet weather the trucks could not get sufficient traction to climb some of the hills and were likely to stick in the mud in certain places, so that no attempt was made to run them unless they were on the road when the rain started. This lost time amounted to about 5 per cent. of the total, but, whenever possible, it was utilized in making minor repairs. The price of gasoline, was from 17 to 21 c. per gal. Rubber tires were used throughout. Drivers were paid $4.50 to $5 per shift, and a return trip to Tucson was counted as two shifts even when made in one day. Drivers were provided with a room in Tucson and were paid for all time lost due to causes beyond their control. Trucks were loaded one way only.

Jan 7, 1916

By COREY C. BRAYTON

OUR first air travel began at Barranquilla on a trip to the platinum dredging-operations at Andagoya. The fare is based on a minimum weight of passenger, and I will have to admit that the minimum is too low. To make this trip by boat would have necessitated going back to the Canal, thence down to Buena Ventura, and up the San Juan river, which would have taken, counting delays, two or three weeks. The time by Scadta airplane was six hours. We stopped at Cartagena for a day to look over that historic city. The route from there lay along the north coast to the mouth of the Atrato river, then up this river, over the jungle, and over a divide some 300'ft. in elevation and down the San Juan river a few miles to Andagoya at the junction of the Condoto. The General

Jan 1, 1930

By C. A. Heiland

The new geophone described herein was developed by Charles H. Hull, instrumentmaker of the Colorado School of Mines, and the writer. The first geophone was invented during the war for the purpose of detecting enemy sapping or underground mining operations and for locating enemy artillery. It is based on the principle of the seismograph—a heavy lead mass suspended by one or two diaphragms, which are clamped to an air-tight case. When the ground vibrates during the transmission of sound waves, the case moves with it while the so-called steady mass remains practically motionless. Attached to the top of the casing is a hose leading to an earpiece shaped like a stethoscope. When the mass and the diaphragm move up and down in the case, the air is compressed and rarified in the inside; thus the vibration is communicated as sound wave to the human ear. The geophone combines a surprising simplicity of construction with an extreme sensitivity. Other listening instruments were developed during the war, adaptations of the telephone and the microphone—that is, instruments operating through the medium of electricity—of which the so-called seismicrophone, an adaptation of the carbon-granule microphone receiver, probably has found the greatest application, but such instruments apparently have not proved as useful as the simple geophone despite obvious advantages arising from the use of electricity. The carbon receivers were more subject to extraneous noises and to what is called "frying," and they did not offer the advantage possessed by the geophone; namely, the simultaneous use of two receivers, which makes it possible to determine the location of the source of sound. During the war, the U. S. Bureau of Mines made a study of the geophone and of the propagation of sound waves through rock. These studies have been continued, as the earlier results proved the possibility of using the geophone in various non-military ways, principally in mining, and the results of these studies have been published.'

Jan 1, 1932

By O. W. Rees, Gilbert H. Cady

Unit coal calorific values represent a close approach to pure coal values; they possess characteristics theoretically inherent in the latter values. They are essentially uniform in the same seam for areas possessing essentially uniform geological environment. They are higher in older than in younger coals in most cases, and in deeper than in shallower coals. In general, they display characteristics closely in accordance with expectation assuming that they are essentially indices of rank. Because it possesses these characteristics, the unit coal value is essentially a standard value, characteristic of each bed in each local region. Hence it can be used as a basis for determining the accuracy of results in newly established laboratories, or when new equipment is installed, or in checking the results of different laboratories, or even in determining the character of coal as mined or prepared if ash, moisture and sulfur values are known. DISCUSSION (A. C. Callen presiding) R. P. Hunson,§ Wayland, Ky. (written discussion).—One of the interesting observatioris made by the authors is that there is a more or less definite correlation between unit coal calorific values and the geological environment of the coal bed. It is very interesting to note that, in general, the unit B.t.u. value increases with the increase in the probable original depth of burial, and that each seam tends to increase in calorific value toward the areas of diastrophic instability. It is generally conceded that Parr's formula, for determining unit coal values, is about as accurate as any formula subsequently proposed for the same purpose. In his formula, Professor Parr did not differentiate between the sulfur present as iron pyrites and that present as organic sulfur. However, the practical application of the formula has shown that this is of little consequence. I agree with the authors that unit coal calorific values are useful ill determining the accuracy of calorimetric determinations, and in determining the character of the

Jan 1, 1934

By Elmer W. Pehrson

The term "survival" in the title means the preservation of a society in which men are free from the political and economic restraints that characterize totalitarian systems, be they communist, socialist or facist. It means the ability to withstand the enemy's offensives in the fields of propaganda, commercial competition and, if necessary, war. The temptation to substitute "victory" for "survival" is great but a realistic appraisal of the creeping socialism and demagoguery that pervade our time indicates that we may have to be content with survival in status quo. "Mineral strength" means assurance that adequate supplies will be available to meet all the contingencies of cold and hot wars. The overall mineral position of the U. S. viewed in the light of these premises is far from secure. It is true that we are the leading producing and consuming nation of the world, but the Soviet Union is gaining and the Sino-Soviet Bloc confronts us with a sobering potential. The emergence of the Common Market in Europe as an economic and political unit places a third independent entity into the competition. Our total mineral output continues on an up- ward trend but the reverse is true in certain strategic commodities. Moreover, consumption is moving ahead faster than production so that there is increasing dependence on imports which has significant adverse geopolitical connotations. There is widespread belief that our resources can at least maintain present levels of self-sufficiency during this critical period in world history, but social dreamers, the labor monopoly, and trade and taxation policies have discouraged aggressive activity in exploration and development, and access to essential foreign sources is threatened by a variety of circumstances. Our stockpiles, belatedly built up to achieve minimum protection against shortages in time of war, are under. political attack and threatened with partial destruction on the basis of what are at best uncertain assumptions regarding the new: look of global warfare.

Jan 11, 1962

By J. D. Kalasky

Continuous mining has revolutionized the coal industry but intensified the problems of earlier mechanization. From the installation of the first miner, it was recognized that face ventilation would be one of these problems. To establish an efficient work cycle for the equipment being used, conventional mechanized mining provides four or more development faces. Continuous mining, relying on a single machine, requires only one face, although more than one can be driven alternately by the same machine. In gaseous areas mined by the older methods, the intermittent rate of exposure allows time for the face to bleed off or be cleared, and the width obtained with conventional units makes it possible to hang a brattice line almost to the face. Continuous mining increases the ventilation hazards; there is no margin of time, and very limited space. For all practical purposes, continuous miners available today can be grouped into two major types, rippers and borers. The two can be further classified, respectively, as flexible and rigid. Both types have been in operation in U. S. coal mines for the past five to ten years in a number of seams, under various conditions ranging from slightly gaseous to very gaseous. Common methods of face ventilation utilizing jute or plastic brattice material for line curtains, stoppings, and checks have so far met with success. Air volumes to operating sections are greater than for conventional mining, and specific instructions have been given to section crews stressing the precautions needed in dealing with a steady rate of gas emission and the importance of maintaining reasonably air-tight brattice to direct a good steady flow toward the face at all times. Operators of continuous miners, as well as the foreman on each section, are equipped with an approved safety lamp for gas testing. When the miner is in steady operation, tests for gas at the face are made at 15 to 30-min intervals, depending on the

Jan 1, 1960

By T. C. Shelton, W. M. Huang

One of the problems arising from the use of modern machines and systems in coal mining is increased emission of explosive gases into the mine passageways. Interest in degasification of coal seams has grown. The authors summarize the results of coal permeability tests done at Virginia Polytechnic Inst. on one of the fundamental aspects of the problem. There are undoubtedly many factors that affect the emission of gas from coal but the permeability of coal to gas flow would seem to be fundamental. However, there is very little information on coal permeability to gas flow available in the U.S. at the present time, despite the fact that such knowledge would appear to be significant in any degasification effort. Studies made recently in the mining engineering laboratories at Virginia Polytechnic Inst. have determined values of permeability on 1-in. cubes of selected coals. COAL PERMEABILITY The permeability values given in this paper are based on adaptations of Darcy's law formulated by Henry Darcy in I856 from experiments with fluid flow in porous media.' Using air as the gaseous fluid, they were obtained by employing similar methods as are used to dete1:mine the permeability of petroleum and gas reservoir rock specimens. Permeability is. a measure of the ease with which fluids flow through a porous substance, and it is governed by the connected pores within a porous medium. If a few large-sized pores, fractures or channels are present within the medium, the medium can have great permcnability without significant porosity. It is reasonable to assume, therefore, that the permeability of coal, due to its structure, is based on fractures connecting the pore space left as the result of some degree of devolatilization or other changes of the substance from which coal was formed. The results of this irvestigation tend to validate this assumption in that the values obtained indicate a close relationship between the rank and permeability of coal. COALS TESTED AND PROCEDURE The coals whose permeability values were determined in this investigation are given in Table I.

Jan 1, 1962

By Edgar Rickard

E UGAR RICKARD comes of a long line of mining men and was born at Pontgibaud, France, in 1874, where his father was then in the course of his professional work. Later his father came to California and was until his death prominently connected with milling in that state and Nevada. Edgar Rickard grew up at Berkeley, attended the University of California, graduated in 1895 from the mechanical engineering course, and remained a year longer for post-graduate work in the College of Mining. His first job was as assarer for the Mountain Copper Co., Keswick, Cal., in 1896. The following year he was assayer and surveyor for the Cornucopia Mines, Oregon. In 1898, he joined the staff of the Venture Corporation, London, and for two years made examinations for them in various parts of the world. He served as mine manager at Cripple Creek and at the Briseis tin mine, in Tasmania. From 1901 to 1905, he was general manager of the Progress Mining Co. in Lower California, but when his cousin, T. A. Rickard, bought the Mining and Scientific Press he was persuaded to come to San Francisco as business manager of that periodical. A few years later the two cousins went to London and started the Mining Magewine there as a joint venture, Edgar being the business manager. In 1915, he took over control, T. A. Rickard returning to California to devote his time to the Mining u.rbd Scientific Press. In 1917 Edgar Rickard sold out to his British associates and came home to serve in the Food Administration through the war. Rickard was one of the first of the American engineers called to his staff when Herbert Hoover began his relief work by helping stranded Americans home at the be- ginning of the war and he has been with him constantly since in the Commission for Relief in Belgium, the

Jan 1, 1929

By Randolph H. Schnitzel

MARINGER and schwopel have investigated the internal friction of high-purity molybdenum. After light tensile deformation, they observed internal-friction peaks at about 230° to 290°C, 310" to 370°C, and 820° to 870°C, which they have attributed to the interstitials carbon and nitrogen, and to stress relaxation across grain boundaries, respectively. The electron-beam melting technique has been successfully applied to refractory metals including molybdenum. By this technique single crystals and higher-purity levels than those of commercial molybdenum are readily obtained. Since electron-beam processed molybdenum possesses such desirable qualities, it seems reasonable to determine: u) if internal-friction peaks do exist in these single crystals, and b) if so, whether or not these peaks can possibly be attributed to the motion of specific interstitials. The molybdenum crystal used in this investigation received four melting passes in the electron-beam furnace. This crystal was about 11 in. long and had an orientation 4 deg from the [loo]. The process of making wire consisted of grinding the crystal rod to a diameter of 0.040 in. and then electropolishing to a final diameter of 0.030 in. Since Maringer and schwopel have indicated that the peak at 230" to 290°C may be due to the presence of carbon, the wire was cut into two equal lengths and one length was carburized prior to the internal-friction measurements. The critical condition necessary for the controlled addition of carbon proved to be a difficult problem. Therefore, a simpler nonequilibrium method was used. This consisted of carburizing at 2000°C in graphite powder to obtain a case, annealing at higher temperatures in vacuum to partially dissolve carbon into the molybdenum, and then removing the remaining case by dissolving it elec-trolytically. After this treatment, metallographic examination of a small section of the specimen revealed carbides in the matrix. Vacuum fusion and carbon analyses for both the virgin (as melted) and carburized specimens are given in Table I. Internal-friction measurements of these specimens were conducted in an apparatus of conventional

Jan 1, 1964