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By G. Sachs, G. Espey

SIMPLE methods can be used for the determination of the residual stresses in thin-walled tubing if the stresses consist of high tensile stresses at the one surface and high compressive stresses at the other surface Such a stress distribution is approximated in sunk tubing and in deep-drawn shells It is possible to cut sections from such articles in such a manner that a major part of the residual stress is relieved by a bending of the part that is separated from the adjacent metal The circumferential stress is evaluated from the change in diameter D, occurring on splitting a length of tubing (Fig Ib),1-5 or from deflection resulting from the cutting out of a circumferential tongue (Fig Ia) G The bending moment M released by such a flexure is [ ] The release of this bending moment corresponds to the release of stresses, which, in a thin section, vary linearly from one surface to the other, and have the following value in a particular fiber a certain distance (zx from the surface [ ] where C is the section modulus and d is the thickness of the section, the ratio AI C being d 2 for a rectangular section* The maximum stress values at the surfaces are [ ] For most purposes the simpler equations [ ] will be satisfactory, where Dm is the average of the mean diameters of the tubing

Jan 1, 1941

1 Healthy and active Local Section organizations are vital factors in promoting the vigor and growth .of the Institute 2 Activity on the part of Local Sections should be recognized and stimulated by appropriation of funds, from the Institute's treasury, and these appropriations should be as large as is consistent with the relative needs for other activities 3 As between different Sections, the amount of such appropriations should be based primarily on the extent of activities as reflected in the number and character of meetings held and the attendance of the members at such meetings 4 In making a request for funds for any year, the officers of a Local Section should submit a report on the printed form approved by the Directors at their meeting on November 19, 1937

Jan 1, 1952

Horace F. Lunt, York, Montana* :—Two years ago I visited the region described by Mr. Jennings and assisted in the examination of a somewhat similar group of deposits in the White Mesa sandstone on the Navajo Indian Reservation, 125 miles north of Flagstaff and 50 miles east of the Kaibab plateau. There, the Triassic red sandstone is less than 200 ft. thick, and is overlain by a stratum from 200 to 250 ft. thick of white sandstone, which gives the name of " White Mesa" to that locality. The white sandstone shows all phases of crossbedding in great complexity, and evidently marks a period of oscillation and subsidence of the water, or an elevation of the land, at the close of a geological epoch. The prevailing color is white or gray, but occasionally it is red. In structure, it is composed of well-worn grains of quartzsand, from which most of the cementing material has been leached out, leaving it soft and friable. Possibly the cement was ferruginous, as is indicated by occasional traces of red color. The copper-deposits consist of a replacement of the cement of one particular cross-bedded stratum of the sandstone by chrysocolla, having also at times various quantities of tenorite in grains or masses. Some specimens of the ore contain as much as 32 per cent. of copper. Generally the copper-deposits are a few hundred cubic feet in size, and no strict line of demarcation is shown between them and the surrounding sandstone, the bluish-green color of the chrysocolla gradually fading into the white of the sandstone. The ore is apparently associated with small vertical crevices or fissures. Some of the deposits show a distinct vein-structure, while others do not. The origin of the ore is not very clear. Undoubtedly the solutions, coursing through the crevices noted above, played a prominent part in its deposition, as possibly

Jan 1, 1904

By Walter O. Snelling

In combating mine-fires the use of carbon dioxide as a means of producing an atmosphere in which combustion cannot be sustained, has been many times suggested and frequently tried, generally with a fair degree of success. The carbon dioxide is produced by acting on limestone with dilute sulphuric acid, large wooden boxes being used to hold the limestone, and arranged in such a manner that one box may be cleaned and refilled with blocks of limestone while another is being used in generating the carbon dioxide.. The gas is led by means of pipes of large diameter to the location of the fire, tight brattices having been previously put up as close to the fire as possible on every side, so as to limit the space to be filled with the gas to the smallest possible volume. The cost of producing carbon dioxide has been, however, a decided draw-hack to the use of this method, and the danger of producing carbon monoxide by the reduction of the carbon dioxide by heated carbon, and consequently bringing about an explosion, has also tended to prevent the application of this method. The use of sulphur dioxide in combating mine-fires has not, I believe, been previously suggested or tried, and yet the method presents such decided advantages over the use of carbon dioxide that it seems proper to suggest the advisability of considering it as a cheap, convenient, and safe means of fightr ing stubborn mine-fires. 1. Cost, Preparation, etc.—One ton of brimstone, costing from $20 to $30, will produce about 25,000 cu. ft. of sulphur dioxide gas, and allowing for all sources of loss it is probable that sulphur dioxide gas can be produced for about $1,300 per 1,000,000 cu. ft. For carbon dioxide gas, produced by the action of sulphuric acid on limestone, a good estimate would be $4,000 per 1,000,000 cu. ft., provided that sulphuric acid

Jan 1, 1909

By Marvin P. Barnes

The Sacaton open pit copper mine has recently been placed into production. Some problems have been encountered in maintaining grade control due to differences between early block estimates and actual production grade. A study was made using three methods for computing grade for 50' x 50' x 40' size blocks from exploration and development drill holes; 1) The polygonal method, 2) The inverse distance squared method, and 3) The geostatistical kriging method. The results of each were compared against a control block file created by using the assay results of all blast holes drilled in the ore over three benches of the new pit. Results indicate that the kriging technique gave better estimates for grade of individual blocks than did the other two methods for this particular deposit.

Jan 1, 1977

By E. A. Holbrook

AS A whole, engineering schools have not awakened A to the fact that the workmen compensation laws passed in most of our states between 1914 and 1917 effected a quiet but none the less real revolution in. the relations between labor and management; no longer are industrial accidents unfortunate or careless happenings over which we feel a humanitarian interest and sorrow, they are a cost of the process and the finished product, as vital as improved design and increased efficiency. Last year the writer and others made a committee report to. the American Institute of Mining and Metallurgical Engineers on the cost of accidents in the coal industry of Pennsylvania. Comparatively the accident record in Pennsylvania coal industry is not high, yet the direct compensation cost plus the interference with operation cost of accidents was over 5 per cent. of the total cost of producing the coal. This stands out more vividly -if you realize that about 70 per cent. of the' cost of producing the coal is for payment of labor, wages that are fixed and over which engineering efficiency and management skill have little or no direct effect. This leaves 30 per cent. of the cost chargeable .to hoisting, haulage, overhead 'and other items subject to engineering control. One sixth of this is due to cost of accidents. Surely a direct place 'for an engineering attack.

Jan 1, 1925

By J. L. Gillson

Historically, rock deposits and sand deposits of titanium minerals came into production about the same time, although there may be some argument as to what is meant by production. Beach de- posits of heavy minerals in India (Figs. 1-4) and Brazil (Figs. 5) were worked for monazite about the turn of century, but as there was then no market for titanium minerals, these were thrown away. The rock rutile deposits at Roseland, Va., Fig. 6, were worked to supply rutile for titanium chemicals and for coloring ceramics long before there was a titanium pigment business. The pigment industry started about the middle twenties, both in Europe and the U. S., and almost simultaneously the rock deposits at Ponte Vedra Beach near Jacksonville, Fla., were worked for titanium content. Since those days, production from both types of deposits has continued to grow at a rapid rate; many deposits of both types have been found, and reserves have grown to very large figures. In total tonnage of reserves, there is no doubt that the rock deposits are far ahead of the sand deposits; nevertheless there is a very large tonnage of commercial sands available. It is the quality of titanium mineral in the sand and the relatively lower costs of operating sand deposits that have kept them abreast, at least in annual tonnage produced, with the rock deposits.

Jan 4, 1959

By Jackson R. Pellett

INTRODUCTION The Friedensville mine is situated in Upper Saucon Township, Le- high County, Pennsylvania, in the southern central part of the Allentown quadrangle of the United States Geological Survey, approximately 5 miles southeast of the City of Allentown and 4 miles south of the City of Bethlehem. Zinc was first discovered in the Friedensville area early in the 19th century and several mines were operating during the latter part of the century. Zinc oxide was produced in 1853 and zinc metal in 1859. All mining in the area ceased in 1893 chiefly because of an unfavorable economic situation caused by a severe ground water problem and competition from the higher grade ores in New Jersey. Property acquisition by the New Jersey Zinc Company began in 1899 and periodic exploratory drilling was carried on until 1940 when sufficient reserves were proved for development of a mine. Shaft sinking was undertaken in 1947 and, due to severe hydrologic conditions, was not completed until 1952. Production began in 1958 and today the mine is producing about 64,000 tons of zinc concentrate per annum. The concentrates are trucked to the Company's smelter at Palmerton, Pennsylvania, approximately 30 miles north of Friedensville. The mine also produces from its mill tailings industrial and agricultural grades of limestone for commercial markets.

Jan 1, 1970

By Karl Sundberg

DURING the past few years Swedish geo-electrical prospecting methods have been described in several papers; namely, by us in a paper en-titled "Electrical Prospecting in Sweden," published by the Geological Survey of Sweden, 1925, and in a paper, "Electrical and Electro-Magnetic Prospecting," read by Hans Lundberg at the 1926 annual meeting of the A.I.M.E. In a written discussion on the latter paper, Theodore Zuschlag has made some observations, pub-lished in the Trans. Vol. LXXIV, which has just ap-peared. In this discussion the theories of the Swedish geo-electrical methods are criticized. The statements of Mr. Zuschlag are the reason for, our submitting the following information.1 In developing an art, such as electrical prospecting, the first thing to do, of course, is to make clear the fun-damental principles of electrical prospecting and then apply them to practice. This application cannot, in this case, be made by theoretical calculations only, because Nature is far too complicated to permit of exact theo-retical calculations on the phenomena involved in prac-tical electrical prospecting. Therefore, it is necessary to start with simplified cases, then turn to more and more complicated ones, and, finally, to test the applica-tion of results found, first in the laboratory and then in the field under known conditions.. Only in this way can results of practical value be obtained. This pro-cedure comprises three important parts: theory, the work in the laboratory, and the work in the field. In the papers mentioned above, we have briefly out-lined the work done in developing the Swedish geo-electrical methods, mainly giving some practical results, because these are most important and most likely to interest mining people. Possibly, because the discus-sion of theoretical considerations in our papers has been brief and sketchy, Mr. Zuschlag feels justified in in-ferring that the theories used as the foundation in Swedish electrical prospecting methods are not free from fundamental objections. His fundamental ob-jections are:

Jan 3, 1927

Where Does the Mine Dollar Go? BY PAUL M TYLER (Min & Met, April, 183 3900 words) Wage earners on the job get nearly 50 per cent of the mine dollar; salaries normally take over 5 per cent (less for large metal mines); and less than 20 per cent is expended for supplies, materials, fuel, and power The total of all such specified expenditures, which may be loosely described as "direct costs," has tended over several decades to decline from over 75 per cent to under 70 per cent of the gross receipts from the sale of products of mines and quarries The item of supplies and material is far less important in the extractive industries (mines, forests, and fisheries) than in manufacturing For manufactured products the average cost of raw materials was 30 4 per cent of gross sales, almost double the proportion for the mineral industries, whereas factory wages and salaries accounted for only 33 2 per cent instead of 51 9 per cent Within reasonable limits, the margin above direct costs as herein calculated affords a measure of capital's share in the total realized from sales A preponderant group of mineral industries operate under conditions that permit or require a margin of 25 to 45 per cent At one end of the scale are highly organized industries such as sulfur, fuller's earth and iron ore mining employing much

Jan 1, 1935

By Keith E. Robinson, Brian Stimpson

INTRODUCTION In inclined sedimentary strata slope failure may occur by sliding along bedding and along a discontinuity or weak zone, as illustrated in Fig. 1. This mode of failure may be called 'bi-linear', as the failure surface is comprised of two linear or approximately linear segments. This type of failure has been suggested for the famous Frank Slide, Alberta, Canada (Cruder and Krahn, 1973) in which an estimated 90 M 5 tons (8.97 x 10 MN) of rock separated from Turtle Mountain and buried the town of Frank. Also, with the increasing depth of open pits and the construction of highways through inclined sedimentary strata this mode of failure is of major concern to the rock slope stability engineer. A computer program for calculating factors of safety for this slope failure mode is provided and includes the ability to vary shear strengths of potential slide surfaces, ground water elevations and wedge geometry. LIMITING EQUILIBRIUM MODEL The simple limiting equilibrium model used in the analysis is shown in Fig. 2. It is assumed that jointing is orthogonal to bed- ding and that the interface between the upper and lower wedges there- fore corresponds to a joint plane or planes. No shear strength is attributed to the interface so that the resultant force, P, from the upper wedge acts normally across the interface. The normal loads

Jan 1, 1983

By A. Henry

THE manufacture of wheels of metal for locomotives and cars constitutes an important branch of the iron industry, and one closely related, moreover, to many of the conditions of railway practice, such as speed, safety of passengers, and economy of working. It has been, also, since the introduction of iron roads, a subject of constant study on the part both of engineers of construction and iron manufacturers. The car-wheels at first used in Europe had spokes of wrought iron and a hub of cast iron. Subsequently endeavors were made to make the wheels entirely of wrought iron, by forging successively the different parts which constituted the hub, spokes, and rim. By this treatment the expansion of the heated portions at the last forgings gave rise to interior ruptures in the already cold and finished parts. The metal was thus strained before use, and the wheels broke frequently in service. It was in consequence of these failures, doubtless, that the engineers of this country were led to employ exclusively wheels of cast iron. The railway companies are nevertheless greatly interested in the reduction of the weight of rolling stock, while preserving abundant strength, and by the employment of wrought-iron wheels one may attain this double end if the defects of manufacture which we have just mentioned are avoided. This may be accomplished by making the wheels in such a manner that the different parts are welded at the same time, whereby the interior strains which so frequently give rise to ruptures in wheels successively forged are avoided. This result has been attained by what is known in France as the Arbel process, of which I will give you a short description if you will kindly give me a few minutes' attention. The process may be briefly summed up as follows : A pile of puddled bars of the general form of the wheel to be made is prepared,

Jan 1, 1877

By Adolph Henry

The manufacture of wheels of metal for locomotives and cars constitutes an important branch of the iron industry, and one closely related, moreover, to many of the conditions of railway practice, such as speed, safety of passengers, and economy of working. It has been, also, since the introduction of iron roads, a subject of constant study on the part both of engineers of construction and iron manufacturers. The car-wheels at first used in Europe had spokes of wrought iron and a hub of cast iron. Subsequently endeavors were made to make the wheels entirely of wrought iron, by forging successively the different parts which constituted the hub, spokes, and rim. By this treatment the expansion of the heated portions at the last forgings gave rise to interior ruptures in the already cold and finished parts. The metal was thus strained before use, and the wheels broke frequently in service. It was in consequence of these failures, doubtless, that the engineers of this country were led to employ exclusively wheels of cast iron. The railway companies are nevertheless greatly interested in the reduction of the weight of rolling stock, while preserving abundant, strength, and by the employment of wroughtiron wheels one may attain this double end if the defects of manufacture which we have just mentioned are avoided. This may be accomplished by making the wheels in such a manner that the different parts are welded at the same time, whereby the interior strains which so frequently give rise to ruptures in wheels successively forged are avoided. This result has been attained by what is known in France as the Arbel process, of which I will give you a short description if you will kindly give me a few minutes' attention. The process may be briefly summed up as follows: A pile of puddled bars of the general form of the wheel to be made is prepared,

By D. Hnrrington

THE Dust Symposium was attended by approximately 100 persons, nearly all of whom remained from the starting hour (2 p. m.) until the use of the auditorium was demanded for another meeting at 5:30 p. in. In calling the meeting to order, D. Harrington made a few remarks as to the importance of the health dust problem in mining as well as in general industry and expressed gratification that the subject is now out in the open and that mining people are desirous of ascertaining the facts. B. F. Tillson acted as chairman of the meeting. The milling executive who desires to know what to do to prevent his workers from being unduly exposed to the dust hazard can get much out of the paper by D. E. Cummings, who has been doing much work in mines trying to keep -the dust in the air within safe limits. His recommendations indicate that the main protection of the worker in mines is by adequate ventilation, supplemented by the extensive use of water in drilling, as well as in water curtaining to condition air both in regard to dust content and to temperatures. Blasting was shown to be one of the chief causes for dust and it was recommended that whenever feasible all blasting should be delayed to the end of the working shift.

Jan 1, 1935

By Edward Estabrook

THIS paper gives a brief account of the geologic and production problems encountered in the Grass Creek oil field, the methods used in their solution, and the beneficial results obtained from the work. The author wishes to acknowledge the assistance received from J. H. Pearson and Miss Ninettta A. Davis in the collection of the data and the preparation of the cross-sections. Permission for its publication was given by the officials of the Midwest Refining Co. and the Ohio Oil Co. The Grass Creek oil field is located in Ts. 98-99 W., R. 46 N., Hot Springs County, Wyo. The productive area includes about 2 1/2 mi. (4 km.) on the apex of a great anticlinal fold occupying more than 150 sq. mi. Fig. 1 shows the structural contours of the field. Oil was dicovered in the field in June, 1914; development proceeded rapidly and production rose to a maximum in 1918. The marketed production has been approximately as follows: BARRELS BARRELS 1915 94,073.5 1918 2,946,774.27 1916 1,404,183.97 1919 2,000,584.84 1917 2,780,697.51 1920 1,485,080.94 About 350 wells, 800 to 1500 ft. (243 to 457 m.) deep have been drilled to reach the upper oil sands; two companies, the Ohio Oil Co. and the Midwest Refining Co., operate the entire field.

Jan 2, 1922

By William B. Plank

PRESENT enrollment of 182,361 students in the engineering schools of the United States and Canada represents an increase of 6.6 pct over the enrollment in these schools in 1951-52. Thus is brought to a halt the steady decrease in engineering enrollment that began with the close of the 1947-48 academic year, five years ago. The mineral engineering student picture is similarly encouraging. In the United States schools, 9453 students are preparing themselves for positions in the Mineral Industry. This is an increase of 8.3 pct over last year as compared with an increase of 6.6 pct in the total United States engineering enrollment. The rate of recovery for the mineral engineering group is thus more rapid than for the engineers as a whole.

Jan 4, 1953

By D. H. Bacon

Nearly all men are too busy with their own affairs to keep informed of the progress in other lines. From time to time we read statistics showing the development in some industry that astonish us; but the feeling of surprise soon fades: to be followed by others that likewise pass away. A short resume of what has been done in one line may be of interest. Down to late in the fifties the ore-product of Lake Superior mas handled over a mule-tram-road to Marquette; now the Duluth, South Shore and Atlantic, the Chicago and Northwestern, the Wisconsin Central, the Duluth, Superior and Western, the Duluth, Mesabi and Northern, the Duluth and Iron Range and the Lake Superior and Ishpeming railroads serve the shippers. Down to nearly 1870 a 700-ton ship was an enormous craft, the loading of which required two days; the unloading being seldom accomplished in that time. In 1871 the largest ore-barge carried 1050 toils and made twelve trips per season. Now the cargoes reach 5000 tons, the loading requiring less than three hours, and the unloading ten hours. Now the mines cover more land than was familiar to even the " timber-cruiser " when the Jackson mine was opened. The annual shipments have grown from a few thousand to 10,000,000 tons, and the ability of the mines to produce is not taxed. Lake-freights are at one-eighth, and rail-freights at one-quarter, of early prices. The deeper waterways, commodious locks and large ships of to-day are in a greater measure due to the movement of ore than to any other cause. Great savings have been made in each detail of each department. The only item of cost that has not been lessened, I am glad to say, is the money paid to men. Wages, measured by what they will buy, are as high

Jan 1, 1898

The rich Tiller seam in southwest Virginia averages 10 to 15 ft in thickness. But because it is separated into two benches, mining engineers for years considered it neither physically nor economically feasible to mine. Profitable recovery of this coal has been made possible only by: full-seam mining with automatic machines; and the largest and most highly automated coal preparation plant of its kind-a plant ten stories high which washes, screens, and dries at the rate of 1500 tph, and produces both metallurgical and steam coal products. The Moss No. 3 preparation plant of Clinchfield Coal Co. Div. of Pittston Co. is located at Clinch- field, Va., only a short distance from the 450-tph Moss No. 2 plant, and was designed, built and erected by Link-Belt Co.

Jan 7, 1959

By John Griffen

THE distinguishing principle of the Tromp process is the use of a medium in the bath which is not stable, i.e., the solids will settle and the density of the medium increases with depth. A medium of uniform density can most easily be effected by agitation or by means which increase the viscosity of the medium. Either of these works against the sharpness of separation of coal from its impurities. The Tromp process grinds the medium solids to relative coarseness, allows them to settle downward in the bath without hindrance, and introduces horizontal currents of medium at intermediate levels between top and bottom of the bath. This prevents any accumulation of particles denser than the upper layer of the medium from which the clean coal is conveyed away or an accumulation of particles lighter than the bottom layer or medium whence the refuse is removed. In a relatively shallow bath making a two-product separation, the intermediate horizontal currents sweep these intermediate gravity materials away to be discharged with the refuse removed by the conveyor. Such a system provides a number of advantages. The gravity of separation can be changed simply by changing the density of the medium without changing particle size of medium solids or other conditions, as would be necessary with a system requiring uniform or stable density throughout the bath. Some installations in Europe separate at 1.40 sp gr on one shift, producing a superclean coal, and on the next shift reclean refuse from dry cleaning units and effect a separation at 1.80 sp gr. Medium solids may be much coarser in size consist, which reduces the viscosity of the medium and promotes its fluidity and in turn the sharpness of separation. Coarser medium solids with a more rapid settling rate are much more easily recoverable from the dilute medium rinsed from the products. The Tromp process is not limited to the use of medium solids having magnetic properties. Instal-

Jan 1, 1952

ROBERT VAN ARSDALE NORRIS, who died at his home at Wilkes-Barre, Pa., on April 20, 1928, was born at Newark, N. J., on May 2, 1864, of parents who were direct descendants of such sterling New Eng-landers as Governor William Bradford, John Alden and Timothy Dwight. He went to the Collegiate School in New York and then to the Colum-bia School of Mines where he graduated with the class of 1885, having among class-mates A. S. Dwight, E. N. En-gelhardt, H. L. Hollis, G. B. Lee, Richard Moldenke, Wil-bur Sanders, Joseph Struth-ers, E. A. Wiltsee, and I. H. Woolson. His marked ability even among so many men of unusual ability caused him to be chosen as assistant to Pro- fessor Munroe in the summer school of mining and survey-ing immediately after gradua-tion, and he shortly after was also inspector of dredging operations on the Maurice River improvement work, Millville, N. J. The follow- ing year he worked in the chemical laboratory of Herman Behr in Brooklyn, and toward the end of 1886 he joined the staff of the Pennsylvania R. R. Coal Co. and the Susquehanna Coal Co. as assistant engineer. Six years later he was made principal assistant en- gineer and in 1900 he was made chief engineer of these companies. In 1904, he withdrew from them and estab- lished an office as a consulting engineer at Wilkes- Barre, later taking his son, Robert V., Jr., into partner- ship with him. They acted as consulting engineers for the coal department of the Delaware, Lackawanna & Western R. R. Co., the Lehigh Valley Coal Co., Coke Bros. & Go., Inc., the coal department of the Pennsyl- vania R. R. Co., the Wilkes-Barre & Hazelton R. R. Co., the Sterling Salt Co., and others, specializing in ex- amination and appraisal of coal properties, and also matters of Federal taxation.

Jan 5, 1928