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Jan 1, 1956

By G. St. J. Perrott

A study of certain fundamental characteristics of liquid-oxygen explosives has been made. A discussion is given of the factors affecting the life of the cartridge and the relation between explosive strength and oxygen content. The explosive properties of L.O.X. cartridges packed with a variety of lampblacks, gas blacks, and other materials have been experimentally determined by means of the ballistic pendulum, Bichel gage, and measurement of the rate of detonation. DURING the past year, the Bureau of Mines has carried on an investigation of liquid-oxygen explosives (L.O.X.) to supplement the work described in previous publications.' The present paper gives results of the first part of this work, which was a laboratory investigation of the properties of typical combustibles used in L.O.X., and the relation of these properties to the absorption and retention of oxygen by the explosives and their explosive characteristics. No attempt will be made to describe the development of liquid-oxygen explosives, because this phase of the subject has been well covered. The L.O.X. cartridge consists of a paper wrapper filled with an absorbent combustible material that is saturated with liquid oxygen by soaking it therein. After saturation, the cartridge is removed from the liquid and fired with fuse and cap, or electric detonator, in a manner

Jan 12, 1924

By William Fink

ALUMINUM forms not only binary compounds with most of the metallic elements but also forms many ternary or more complex constituents. Several of those occurring in the more important alloy systems have been identified under the microscope and the action of various etching reagents has, been carefully studied.' The determination of the structure and composition of these complex constituents is a matter of some difficulty and little information is available. X-ray crystal analysis offers a promising method for the study of such constituents. First, and of considerable importance, is the possibility of recognizing the presence of a given constituent by means more positive than microscopic observation. Evidence can also be obtained concerning the nature and composition of the constituent in question and ultimately it should be possible, at least in some cases, to describe the structure including the relative locations of the various atoms. In this paper some results of an uncompleted study of the constituents of the aluminum-iron-silicon system are given and the methods employed are described. Inasmuch as iron and silicon are the chief impurities in aluminum, the constitutional relations of this system are of fundamental importance in the metallurgy of pure aluminum and its alloys; the system has been studied by several investigators and the more important contributions have been reviewed recently.2 Fig. 1 shows the structure of the aluminum-rich alloys after prolonged annealing at 560° C., in accord with one of the most recent investigations.3 The ternary alloys examined in the course of the present investigation were all annealed at 550° or 560° C.; in fact, some of the specimens were the identical ones used by Dix and Heath, who kindly supplied them for this work. Since the results

Jan 1, 1930

There are two types of shovels currently used primarily as mining tools-the stripping shovel and the quarry-mine (Q-M) shovel. The two types have basically the same features, the main difference being in size. The stripping units are giant four-crawler shovels that operate by placing overburden alongside in a mined-out area. The Q-M units, on the other hand, are two-crawler shovels that usually load into trucks or trains. Powering Systems A typical stripping or Q-M shovel is fully electric, receiving power through a trailing cable that is connected to a large motor-generator set with multiple generators. In the full Ward-Leonard system, each generator furnishes d-c power to separate motors which drive the mechanisms for the principal motions of the shovel-hoist, crowd and swing.

Jan 10, 1967

By George Moore

IN spite of many investigations of the occlusion of hydrogen in iron, the nature of the process and the reasons for the accompanying effects upon the metal are still open questions. This is in large part due to three causes: (1) the difficulty of obtaining iron of adequate purity as starting material; (2) the occurrence of allotropic transformations, which compli-cate the effects; and (3) the fact that the body-centered cubic modifica-tion does not lend itself readily to crystallographic investigation. The present paper attempts a critical review and correlation of the somewhat scattered and disconnected existing observations, and an experimental determination of the extent to which the conclusions that appear to follow from these are applicable to iron of really high purity, studied under well-defined conditions.

Jan 1, 1939

Jan 1, 1918

By James M. Hodge

The Cumberland Gap extension of the Louisville and Nashville railroad, recently completed from Cumberland Gap to Norton, 71 miles, connects at the latter point with the Norfolk and Western, making a direct through line from Louisville to Norfolk. The whole of this connecting link skirts the southern boundary of the southwest Virginia coal region, but for the first 57 miles of its course it is separated from the coal by a mountain range (Cumberland mountain and its extension, Stone mountain), which bars entrance to the field from that direction, excepting at Pennington Gap, where access may he had to a small area only, which has not yet developed any very satisfactory coal. The railroad passes through the range at Big Stone Gap, and for the last 14 miles of its course to Norton is in direct contact with that part of the coal region known as the Big Stone Gap coal-field. By this road a western and southwestern outlet from the field is secured; the Clinch valley extension of the Norfolk and Western railroad gives exit eastward from Norton, and the South Atlantic and Ohio railroad, built through Big Stone Gap simultaneously with the L. & N. R. R., delivers the coal to points south and southeast. Besides these lines already built, an early connection with the East Tennessee, Virginia and Georgia railroad, via its Rogersville branch, is probable, and connections with the railroads of eastern Kentucky are projected. The Charleston, Cincinnati and Chicago railroad has already done some grading on one of the latter, but the rugged country intervening will prevent its construction till the demand for it becomes urgent. The coal-field embraces in Virginia about 120 square miles, to which should be added some 30 square miles in Kentucky, also tributary to Big Stone Gap, the whole of it underlaid by coal, probably of workable thickness, and much of it by two or more such beds. The determination of the boundaries of the field, however (except on the south, where Stone mountain forms a natural limit beyond which only a small, isolated tract of coal is found), is involved in much

Jan 1, 1893

By Harry L. McNeill

THE Selective Media Process was developed by the author in a laboratory provided by The Steårns-Roger Manufacturing Co. It is the outcome of an [ ] investigation into the possibilities of coarse beneficiation by sink and float without using the conventional heavy media. Commercial work to date has been limited to the treatment of minus 3/8-in. iron ore at the Hill Trumbull washing plant of the Cleveland Cliffs Iron Co., at Calumet, Minnesota. Two cut away prints of the machine are shown (Figs. I and 2). A rotary conical impeller is mounted within a stationary cone (Fig. 2). This impeller is adjustable vertically by a 12-ton screw jack. The speed of the impeller can be varied from 14 to 32 r.p.m. by the Reeves variable-speed motor pulley mounted on the 7 ½ -hp. motor drive. Attached to the bottom of the stationary cone is the automatic control valve for sink product, actuated by a ¼ -hp. gear motor. The sink product is dewatered in a conventional drag driven by a 7 ½ -hp. motor and discharged onto an inclined conveyor containing from 6 to 10 per cent moisture. Two plants are operated at the Hill Trumbull property. All the ore is first treated in a typical washing plant (Fig. 3). When treating "wash ore" a finished concentrate can be produced by the log washers and Akins classifiers, as the separation involves only fine silica (minus 48-mesh) and free iron. However, when "jig ore" is fed to the washing plant the coarse

Jan 1, 1946

By Robert H. Aborn, J. J. B. Rutherford

It is now well known that troublesome intercrystalline corrosion may occur in austenitic stainless steels following exposure of the metal to a temperature within the range 1000° to 1500° F. (540° to 815° C.). The present paper describes a satisfactory method of estimating the extent of such corrosion, based on the measurement of the electrical resistance of a specimen before and after attack. This new method enabled us to study quantitatively the effect of several factors upon intergranular corrosion in the 18 Cr, 8 Ni type of alloy. The results show that susceptibility to this attack increases with increasing carbon content and grain size and appears to pass through a maximum for certain combinations of temperature of sensitization and period during which the alloy was maintained at that temperature; and are in complete accord with our interpretation of the mechanism of this phenomenon. The method is probably applicable to other metals or alloys subject to intercrystalline attack, such as the aluminum alloys of the duralumin type. The methods hitherto in use for estimating the degree of intergranular attack fall into three types: (1) microscopic examinationll (2) macroscopic examination of fractures, and (3) determination of the time required for complete failure or disintegration.2 None of these lends itself very well to a measurement of the extent of corrosion. The first two are qualitative in nature and the third provides an arbitrary value largely dependent on individual judgment, since failure is a progressive phenomenon and not a sudden event. Our experience is that weight-loss determinations, although valuable in some types of corrosion investigations, bear no simple relation to intercrystalline corrosion in this type of alloy, as is to be expected since the phenomenon probably involves only the thinnest films between adjacent metallic grains. Measurement of electrical resistance has been used recently in the study of some types of corrosion,3 but seems not to have been applied to

Jan 1, 1932

By Frederic P. Dewey

At the Seventh International Congress of Applied Chemistry I presented a paper,' The Assay and Valuation of Gold-Bullion, in which are briefly mentioned a few illustrations of different methods of sampling gold-bullion, particularly cyanide-bars. Since then I have carried on an extensive investigation upon the sampling of gold-bullion in relation to its effects upon the assay-results, in connection with the statement of accounts between the smaller assay-offices of the United States which purchase gold-bullion and the mints where the purchases are re-deposited. Under the name of gold-bullion are included metals of widely different composition. We may have practically pure metal, 999.75 fine or even more in gold; alloys of .gold and silver with only trifling amounts of base metal; alloys of gold and copper with trifling amounts of other metals; ternary alloys of gold, silver, and copper, or gold, silver, and lead; and most complex alloys of from five to eight or more constituents of ordinary occurrence, besides some of the rarer metals occasi'onally. In any one or all of these classes we may have one or more of the metalloids, which may add to our difficulties. Of course, with metal 999.75 fine in gold there is only slight opportunity for different samples to differ in fineness, but on such fine metal we expect the assays to agree very closely, and the sampling must be done with the utmost care. When possible, dip- or granulation-samples of the molten metal should be taken; but when it is necessary to sample bars, the chief point to guard against is surface-dirt.

Jan 1, 1913

By H. A. Guess

INTRODUCTION. HISTORY AND PRODUCTION STATEMENTS. SOUTHEAST Missouri is the oldest of the large producing districts of the United States. The first recorded production from disseminated ores was in 1869, although for many years prior to that time lead had been mined from shallow pockets, and steady growth in production has been shown ever since, the greatest increases being during the past five years. The production by years for each of the operating companies from 1869 to 1907, inclusive, is given in Table I. In Table II. is given the production by years from 1908 to 1912, inclusive, for the district as a whole, showing the tonnage of crude ore mined, yield in concentrates, average assay of concentrates; yield in metallic lead both per ton of crude ore and in total; also approximate value of the yearly production.

Jan 12, 1913

By R. Woodward Moore

A GRAPHICAL method of analyzing the data obtained from shallow earth-resistivity depth tests is presented. The method is based upon empirical results and has no theoretical basis. The usual apparent resistivity-electrode spacing curve is used together with a cumulative resistivity-electrode spacing curve plotted on the same sheet. The greatly reduced scale required for plotting the cumulative values of resistivity together with the effect of the summation of the individual resistivity values serves to minimize the effect of purely local surface anomalies and inadvertent errors of measurement. The point of intersection of tangents or straight lines drawn to intersect at zones of maximum curvature in the cumulative curve indicates the depth to the underlying material. Numerous figures are presented in which data from published reports and from recent field studies are analyzed and the results compared with actual depths established by borings or with depth values obtained by the use of theoretical methods of analysis. Smoothly rounded curves of apparent resistivity such as are often obtained in the field, and which have been a serious drawback to attempts to analyze the data empirically heretofore, appear to be susceptible to rather accurate analysis by the method described. The method is best suited to analyses involving shallow two-layer formations. It has been applied successfully, however, in analyzing the data obtained from tests made over shallow three-layer formations. As with most empirical methods, its chief advantage is its simplicity and ease of application.

Jan 1, 1944

By S. H. Penn

Preliminary experimental evidence seems to preclude the use of unlubricated mechanical force drills on the moon. Measured values of the coefficients of friction and adhesion between metallic and nonmetal-lic solids have been shown to increase in an ultra-high vacuum environment. The paucity of real knowledge of the influence of a hard lunar vacuum upon interacting solid surfaces, relegates current proposals to sample the moon with a mechanical force drill, to the equivalent of wildcatting on earth. Within a few years, drilling will be attempted on the lunar surface with tools that have been designed with parameters that are normally considered for most conventional terrestrial drills. Lunar drills must be light in weight, portable, have reasonable penetration rates, low manpower requirements, etc. Although the initial equipment cost is expected to be high, this will probably not be a critical factor. Early lunar drilling will be limited to shallow holes with depths of 10 ft or less. The primary function of these holes will be to furnish samples of lunar surface materials but they may also be utilized for other purposes, such as geophysical experiments. Instruments may be installed in them capable of measuring thermal diffusivity, gamma radiation, etc. As sampling will be the primary objective of the earliest holes, sample contamination is a parameter that effectively excludes such otherwise promising techniques as explosive or plasma jet drilling. The most desirable method is probably some form of mechanical force drilling that has the capability of operating in the extreme lunar thermal environment (125° to 37S°K), high vacuum (10- l3 torr range), and low gravity.

Jan 1, 1968

By Donald R. Reichmuth

Most brittle solids are relatively weak in tension and this weakness can be very significant in determining their performance in structures and excavations. Consequently, accurate knowledge of the tensile strength of brittle materials has long been recognized as important. In the past, measurements of the tensile strength of materials such as concrete, ceramics, and particularly rock have been hindered by problems encountered in fabricating test specimens and in accurately loading them. These difficulties have resulted in a scarcity of published tensile strength data. This can be readily seen in tabulations such as Wuerker's "Annotated Tables of Strength and Elastic Properties of Rocks."1 There are now three distinct approaches being used to determine the tensile strength of brittle materials. These are shown schematically in Fig. 1. The first method consists of simply pulling the specimen apart by applying an axial load. Although this procedure is the easiest to understand, the technical problems encountered during testing are numerous. Specimens cannot be readily fabricated into dumbbell-shaped specimen* like those customarily used for testing inetals. Cylindrical specimens cannot be loaded in jaw-clamps because adverse stress conditions arise at the clamping points, which causes unreliable results. An innovation developed by Niles Grosvenor at the Colorado School of Mines, in which the load is applied through steel-end caps glued to the ends of the specimens, has considerable merit, hut the samples are costly to prepare.2 All tests using a direct pull are further handicapped by the possibility of small amounts of bending being present, the specimen's surface condition, and

Jan 1, 1968

By L. W. Kesler

Kansas produced 41,966,773 bbl. of oil in the year 1927, thereby taking fourth place among the oil-producing states of the Union. The daily average production decreased from 121,609 bbl. in January to 110,244 bbl. in December. Due to excessive flush production and the resulting decline in the price of crude during the year, operations, both in proved and outlying districts, were reduced materially from those of 1926. There were 2338 completions in 1926, but only a total of 1333 in 1927. Regardless of this decrease in the total number of completions, Kansas made a slight gain in total production for the year, producing 620,262 bbl. more than in 1926. This is accounted for, in part, by the comparative long life of the settled production from the Bartlesville sand areas to the east of the Nemaha granite ridge, and by prolific production in eastern Summer County from horizons new in their importance in the state, productive here at two localities along the axis of the granite ridge (Table 1 and Figs. 1, 2 and 3.) For convenience in further consideration, the state is divided into Eastern and "Western" Kansas. Special emphasis will be placed on those areas in the state of which but little is generally known, and which have not been given detailed consideration in previous publications.

Jan 1, 1928

By Louis A. Panek

Ground movements in the zone adjoining an active cave were measured at four sites in the San Manuel Mine. Measurements were made to detect extension and inclination, basic components of displacement, which can readily be duplicated by mine personnel using relatively simple equipment. The displacements demonstrated the development of a zone of strain relief surrounding the active cave, within which the ground tends to migrate toward the cave, and extension cracks develop tangential to the cave. This expansion of the ground surrounding an active cave can be exploited to promote future caving; it also creates special problems with respect to the design of an effective ground support system for mine openings in the production area.

Jan 1, 1981

By Alan F. Stewart, Douglas R. Piteau, Dennis C. Martin

Three examples of open pits where toppling failure controls the stability and design of the slopes are described. Two examples involve the design of overall slopes in base metal mines. The third example concerns the analysis and design of remedial measures to prevent toppling failure from occurring in a critical slope in a coal mine. The analytical techniques for assessing toppling failure on a rational basis are discussed for the three examples. This includes an assessment of the important parameters which govern the stability for the toppling failure mode. The geological setting and input data for each example are described, as are the important external or limiting factors pertinent to the sites in question. A statistical cumulative technique was used to assess one of the most important input parameters in the two examples involving overall slope design. Both deep-seated toppling failures, involving the entire slope, and shallow bench failures are considered. Results of the stability analyses and their related engineering significance with regard to slope stability and design are discussed. A sensitivity analysis of various parameters is effectively utilized. Design charts are developed and evaluated accordingly. In the example where toppling failure was unavoidable, the rationale for design of stabilization techniques to prevent toppling is discussed.

Jan 1, 1983

By Evan Just

Government aid, regulation, and participation in the mineral industry are not new; they date back to the time when man first adopted communal living. Even in primitive tribal life, the obtaining of arrowhead or ceramic materials, washing of gold, or mining of copper were specialized activities, under tribal sponsorship. Later, when kingdoms, dynasties, and hierarchies developed, titles to mining properties were held by the sovereign or the state, work usually being done by slaves. Title acquisition through denouncement developed in Europe in the late Middle Ages and spread to the Western Hemisphere with the Spanish and Portuguese empires. Denouncements still recognized the rights of the sovereign in the requirement to pay royalties, which practice continues in many places today. Thus, anyone who views government participation in mineral activity as "encroachment" has no historical perspective. Only in a few countries and for a few generations have private interests enjoyed the right to exploit mineral deposits without the specific consent of the sovereign or without payment-of-royalty. Governments and the mineral industry have been linked together by other factors. Governments have had special interest in metals and minerals as stores of value and for armaments. Spanish conquests in the New World were energized by the lure of gold and silver. Pursuit of gold led to the American seizure of California in the days of the Forty-niners. The strategic importance of minerals in our own times has called for special steps to stimulate production in national emergencies and to prevent the enemy from acquiring mineral supplies. Our export controls to deny certain minerals to unfriendly countries, purchases for Government stockpile, and subsidies for domestic production are examples. Production regulation by state governments of oil and gas has become a well established routine. In brief, the mineral industry has never lacked aid, regulation, and participation by governments. The entrepreneur who wishes to explore for or develop minerals must deal with governments in most areas before he can begin, because mineral rights are reserved by them. He can proceed through discovery and de-

Jan 1, 1959

By Jack Parker

There are some simple theoretical approaches to pillar design but they leave much to be desired. There are also more complex theoretical approaches, but at this time the most realistic approach is to go into the mines and observe and measure how real pillars are performing under real conditions; to allow the information thus gathered to ferment in our minds - then to project the behaviour of those pillars into our new designs and mining techniques, probably with no formulas at all. Examples, from half-a-dozen different mines, show how a simple- minded approach, through observation and measurement, led to changes in pillar design which often contradicted the textbook but made very significant contributions to mining safety, efficiency and costs. The good news is that we know a lot more about pillar design than we realize. We have, between us, looked at millions of pillars of all kinds, under all conditions, but we have overlooked what they are trying to tell us. We can take problem situations and turn them into opportunities and, in that way, become better stewards of the resources which have been given to us.

Jan 1, 1983

By H. P. Greenwald

Those interested in the early developments and experiments, both in the United States and abroad, that led to modern rock dusting, will find an excellent summary in a paper by George S. Rice,13 published in 1914. The period from 1914 to 1924 was one of intensive experiment on coal-dust explosions in the United States; abroad, war activities and rehabilitation stopped this work over a large part of that decade. American findings were published by the Bureau of Mines, particularly in Bulletins 167 and 268. It is convenient to consider that in the United States rock dusting to prevent coal-dust explosions in mines was initiated in 1924 with the publication of tentative specifications.17 This was followed in 1925 by an investigation of methods and costs12 and approval by the American Engineering Standards Committee of a Recommended American Prac-tice.18 Approximately 13 years have elapsed since this approval, and inasmuch as changes in rock-dusting practice in the United States have been evolutionary, it is necessary to consider this entire period as "recent" in some phases of the work. There have been no official changes in the Recommended American Practice since its approval. This paper reviews as briefly as possible knowledge acquired since the issue of the earlier papers mentioned, through experience in mines and experiments conducted by different organizations engaged in the promotion of mine safety. Size of Rock Dust The Recommended American Practice states that the dust shall be 100 per cent minus 20-mesh and 50 or more per cent minus 200-mesh. Results of large-scale tests on the relative effectiveness of rock dust of different sizes were published by the Bureau of Mines15 in 1933 and are reproduced here as Fig. 1. The limiting curve of this figure shows that

Jan 1, 1940