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By R. F. Mehl, G. V. Smith

The decomposition of austenite in steels, because of its immerse practical importance, has been subjected to extensive study in recent years from the point of view of the mechanism of the process.1"3 Although much information has been acquired, a number of questions, principally of theoretical interest, remain. One is that of the atomic-crystallographic mechanism by which each of the various reaction products forms. The isothermal reaction products of the eutectoid decomposition in plain carbon steels (to which this study is restricted) have conveniently been classified in three general groupings—pearlite, bainite, and martensite. Of these several products, pearlite and martensite have been studied extensively, but bainite has received only scant attention. -As a result, the mechanism of the formation of pearlite and that of martensite are now fairly well understood while a great deal of uncertainty exists regarding bainite. Pearlite Pearlite forms from austenite by the precipitation of alternate platelets of cementite and ferrite, which grow into the austenite matrix.2--5 The rate of reaction may be described in terms of a rate of nucleation and a rate of growth.2.3 Mehl and Smith6 have attempted to determine the lattice relationships existing between the ferrite in pearlite and the' parent austenite. Using a pole-figure method of analysis, it was found that a limited number of ferrite orientations resulted from the decomposition of a single grain of austenite; it was not possible, however, to decide between two assumed ideal relationships, both of which appeared to account for the experimentally determined pole figure. It was definitely shown, however, that the relationship obtaining was quite different from that determined for the proeutectoid separation of ferrite.7 No attempt was made to determine the habit plane (matrix plane to which the precipitate lies parallel) of the pearlite lamellae. Belaiew8 earlier had stated that the number of directions assumed by the pearlite lamellae in a single grain of austenite was 12 (no details were given) and concluded wrong!:!, as Mehl and Smith6 have pointed out, that the lamellae delineate the {2I0} planes of ferrite.* Martensite It is known that martensite is a transiti0nal constituent of body-centered tetragonal lattice,' and that it forms suddenly

Jan 1, 1942

By J. S. Woodward, F. B. Plummer

The measurement of the rate of flow of liquids through sands dates back to 1856, when H. d Arcyb, a French physicist, carried out his classic experiments on the flow of water through sand layers. The earliest recorded data on relationships of pressure to flow of fluids through porous rocks in this country are those of Newell 23 in 1885. The first comprehensive studies of flow were made in 1898 by King15, who measured the rate of flow of water and air through consolidated and uncon-solidated sands and published the results. From 1900 to 1920 there appears to have been little interest in permeability. In 1920 the increase in demand for oil led the U. S. Bureau of Mines to begin a series of experiments to determine subsurface relationships of oil and water and the characteristics of their flow. Mills18 studied the relationship of flow of liquids to text- and structure of the sands, and Melcher17 in 1925 made a quantitative study of effect of changes in pressure on rate of flow of crude oil through Oklahoma oil sands. Since 1930 the importance of flow measurements to production of oil and gas has been emphasized by a large number of excellent investigations. Among these the works of Fettke9.10, BarbI.2, Cloud6, Nutting24-", Bot-set4, Nevin22, Tickell32.33, Fancher, Lewis and Barnes8, Moore, Schilthuis and Hurst19, and Wyckoff, Botset and Muskat"-39 have contributed much to our knowledge of the technique of permeability measurements and to the laws of liquid and gas flow through porous sands. The application of their work has led to the establishment of laboratories for measuring the permeability and porosity of oil sands by most of the large companies. All the investigations, except those of Wyckoff, Botset and Muskat, and Moore, Schilthuis and Hurst deal with linear flow; that is, flow in a more or less straight line through a given cross-sectional area of sand. Three years ago, at the University of Texas, experiments were started to measure radial flow of liquids through sands; that is, flow from all directions toward a central opening—the conditions that operate in a

Jan 1, 1937

By J. B. Newkirk, D. L. Martin, A. H. Geisler, R. Smoluchowski

A FUNDAMENTAL investigation of the mecha-nism of the ordering reaction and of the accompanying changes in properties has been undertaken, since an extensive study of this process could well contribute to the knowledge of phase transitions in alloys. Cobalt-platinum alloys were chosen for the study since they exhibit interesting and unusual permanent magnet properties.1,2. In addition, the ordering reaction in cobalt-platinum alloys is a convenient one to study experimentally because of the high maximum ordering temperature, the large difference in the X-ray scattering power of cobalt and platinum atoms, and the relative ease with which the alloys can be plastically worked into wire and strip. In the early stages of this study, it became apparent that the published phase diagrams&apos;, &apos; of the cobalt-platinum system contained questionable features, in the region of 40 to 60 atomic pct Co, which were considered in another publication by the authors.4 That portion of the research reported elsewhere on the equilibrium states of cobalt-platinum alloys does not confirm the presence of a previously reported, high temperature disordered tetragonal phase and a low temperature body-centered cubic phase. On the other hand, the structure of the ordered phase is face-centered tetragonal with an atomic distribution analogous to that of CuAu.4 This lattice forms from the disordered face-centered cubic phase in such an orientation that the <100> directions are parallel to the <100> direc-tions of the disordered phase. At compositions other than the ideal 50 atomic pct the ordered phase can exist in equilibrium at high temperatures with the disordered phase. A Widmanstatten pattern of plate-like particles of the ordered phase parallel to (110) planes of the disordered matrix is observed when an initially disordered alloy is held at these temperatures. The temperature range of the two-phase region has been determined for three alloys by X-ray diffraction analyses, microscopic examination, and electrical resistivity measurements, and these results are incorporated with some of those of Gebhardt and Köster in the revised phase diagram of fig. 1. The purpose of the investigation reported here was to examine the mechanism of ordering in co-balt-platinum alloys by X-ray diffraction and metal-

Jan 1, 1951

By M. W. Hayward

THE object of this paper is to record and tabulate the data and field observations obtained by the writers and their associates during 10 years of intensive study of lead-zinc deposits in the Cretaceous limestone areas in Northern Mexico, particularly in mines owned by the Cia. Minera de Peñoles, S. A. At the El Paso meeting of the Institute in October, 1930, J. G. Barry made the suggestion that a committee be appointed to correlate the ideas and theories which have been put forth by the numerous engineers and geologists who, during recent years, have made a study of the ore deposits in the area under consideration. The first step in a work of this nature would be to record all of the observed facts, and these facts would have to be accepted by those who attempted to formulate a theory of ore deposition. It is with this idea in mind that the writers have described as accurately as possible the actual, observed facts pertaining to the occurrence of the lead-zinc ores in dolomites or dolomitic horizons. By most writers the term "dolomite," is loosely used to designate magnesium-bearing limestones, regardless of the percentage of MgO present. Since no, true dolomites exist in the areas to be described, we shall also loosely use the terms dolomite or dolomitic limestone to designate those beds having a magnesia content of 5 per cent MgO or more. For a number of years the writers have been impressed with the fact that in areas where dolomite beds occur a large percentage of the lead ore is found in these beds, in spite of the fact that such beds may be overlain or underlain by pure limestone, which one would assume to be just as favorable for replacement as the dolomite, if not more &apos;so on account of its being more soluble in acid solutions than the dolomite. It is true that in some limestone areas, such as the Erupcion-Ahumada districts, Chihuahua, and Providencia, Zacatecas, where no dolomite beds have been found, large tonnages of lead ores have been mined. We venture to predict, however, that had there been dolomitic beds in these areas, the

Jan 1, 1931

By Ottokar Hofmann

In tank-lixiviation, the extraction of the silver from chloridized ore by solutions of hyposulphite salts is performed by filtration. The ore-particles are kept stationary, while the solvent moves down through the mass of ore. The quickness of extraction, other conditions alike, is in direct proportion to the rapidity of the movement of the solvent through the ore. The solution, if left in contact with the ore without moving, displays but very little solving energy. If the filtration is interrupted for ten or twelve hours, and thus solution and ore are left in complete contact for that length of time, it mill be found that, when filtration is started again, the outflowing solution is but very little more saturated with silver than it was at the time of interruption, and that the ten or twelve hours were almost a perfect loss in the total time of extraction. Notwithstanding the long contact, the solution had not become saturated with silver chloride to its full solving capacity. A rapid movement of the solvent through the ore is essential to a quick extraction. This fact is well known ; and the endeavor of leachers has been to hasten extraction by increasing the rate of filtration. Siphons, vacuumpumps and other devices have been used with more or less success; but none of them have given full satisfaction. I have found that, if chloridized ore is brought into rapid contact with a proper volume of moving sodium hyposulphite solution, the silver chloride contained in the ore dissolves almost instantly, and that it is rather the volume of the solvent than its concentrated state which produces this effect. Such favorable conditions cannot be attained in tanks. The rapidity with which a certain volume of the solvent can be brought into contact with the ore-particles is limited by the speed with which the solution descends through the ore; and thus the leaching-time in tanks cannot be shortened beyond the limit set by the filteringcapacity of the ore. In a trough, however, these favorable conditions can be attained by gradually introducing the ore into the moving stream of the solvent. The ore can thus be brought into

Jan 1, 1888

By Edward O’Toole

THe Pocahontas district occupies the extreme southern end of West Virginia, principally McDowell, Mercer and Wyoming counties, and a part of Tazewell county, in southwestern Virginia. The first record of the coal field is a report by Prof. J. P. Lesley, of Pennsylvania, about 1880, in which he mentions a coal opening at the upper end of Abbs Valley, Tazewell county, Va. C. R. Boyd, a mining engineer of Wytheville, Va., published a series of articles in 1881, mentioning coal on Indian Creek, Tazewell county, and on Horse Pen creek, which coals, he stated, extended toward the Ohio River. He also mentions the Abbs Valley coal reported by Lesley. In 1881, F. J. Kimball (who became president of the Norfolk & Western R. R. in 1883)) after examining the Scott mine in Abbs Valley, went northward across Abbs Valley Mountain to the place now known as Pocahontas, where he located what has since been called No. 3 vein of Pocahontas coal. In November, 1882, Jed Hotchkiss and others prepared a cross-section of the Flat Top Mountain coal measures, some notes on which were published by Mr. Hotchkiss, between 1880 and 1892, under the title of " The Virginias.&apos; In May, 1881, the Norfolk & Western R. R. was organized through the purchase of the Atlantic, Mississippi & Ohio R. R., an old line running from Norfolk, Va., to Bristol, Tenn., with branches from Petersburg to City Point and from Glade Springs to Saltville. At that time, charters had been granted for three railroads tributary to the New River Valley, but their proposed routes would indicate that the promoters were concerned with minerals, timber, and a connection with the Chesapeake & Ohio R. R., rather than the development of any coal in the Pocahontas district. One of them was projected to extend up Bluestone River a short distance, but not far enough to reach the coal in the Bluestone Valley, and a little grading was done for a narrow-gage road between New River Station and a point in Giles county, Virginia, near the West Virginia line. All charters and railroads in this district were acquired by the Norfolk & Western R.R.

Jan 1, 1925

By Graham Bright

Metal mines were developed long before coal mines and the early lighting of underground workings was effected by torches and candles. The early coal mines were outcrop workings and little trouble was experienced from gas, but as the mines became deeper and shaft mines were opened it became apparent that an open-fame lamp was exceedingly dangerous where gas occurred. No satisfactory way of lighting gaseous coal mines was found until Sir Humphrey Davy brought out his famous safety lamp in 1815. The introduction of the Davy lamp was a great step forward but it was unsatisfactory from a light standpoint because the gauze absorbed a large percentage of the light given out by the flame. Clanny corrected this by the introduction of a cylindrical glass lens, which not only permitted a free distribution of the light from the flame but added greatly to the safety by eliminating the possibility of the flame coming in contact with the gauze and by protecting the flame against air currents. A very complete story of the flame safety lamp since its inception is given in the U. S. Bureau of Mines Bulletin No. 227, by J. W. Paul, I;. C. Ilsley and E. J. Gleim, published in 1924. A little more recent publication, known as Safety in Mines Research Board Paper No. 4, entitled "The Light Power of Flame Safety Lamps," by R. V. Wheeler and D. W. Woodhead, was published in England in 1927. The flame safety lamp was the only lamp available for gaseous mines for about 100 years. Although the incandescent electric lamp has been in use over 50 years, it was not found safe to use this lamp from wired circuits in gaseous locations. The storage battery was advocated shortly after the development of the incandescent lamp but until the introduction of the tungsten filament in the miniature mine-lamp bulb, the battery lamp was not a real possibility because of the excessive weight of the battery necessary to produce a sufficient amount of light. The actual development of the electric-battery type of lamp took place largely between 1910 and 1915. In England and Europe, the developmenb was almost entirely along the

Jan 1, 1936

By R. Moldenke

The presence of nickel-chromium in pig iron made fro111 Cuban oles is so well known that the word "Mayari" is unconsciously associated with it. Since 1904, when exploration of the Mayari deposits of iron ore in northeastern Cuba was undertaken, there llas been increasing interest in these ores. Tlie Transactions contain numerous references to t1ieln.l This iron ore, which is shipped to the Tinited States in the nodulizecl state, has been thoroughly tested and found very valuable; the deposit covers over 25,000 acres and there is in sight over 500,000,000 tons of ore that, by systematic mining, runs practically constant in composition. With nickel and chromium present, also titanium in sufficient quantities to attract attention, as well as extremely low phosphorus and sulfur contents, the iron founder is naturally interested in the utilization of RInpari ore for pig iron for the better grades of finishrtl iron products. The present point of coilsn~iil)tion ol ILlapri ore is at Sparrow&apos;s Poi111, where hlayari pig iron of ally desiretl coml>osition is made. The composition of the dried ore is about as follows: Iron -29 per cent., silica 3 pc.r cent., nickel 1 per cciit., chroiniun~ 1.5 per cent., alumina 11 per cent., ant1 coinbined water 13 per cent. When nodulized, the iron runs up to nearly 56 per cent., the silic:~, :tlumi~i:i, nickel, and c~llromiurn are slightly highr than the arno~l~its just given. Practically all the, combined wntcr is driven off aild the iiodulizccl ore carries only a few- tenths per cent. of 1 C. M. Weld: Residual Rrolvn Iron Ores of Cuba. Tmns, (1909) 40, 299. C. K. Leitll nnd If&apos;. J. Mcncl: Origin of Iron Ores of Central and Northeostr~n rlbn. Trans (1911) 42, 00. C. W. Hayes: May:~ri and Mos Iron-ore Deposits in Cuba. Idem, 109. J. E. Little: Maynri lron Mincs, as Developed by the Spanish-American Iron (&apos;0. Idem, 152. J. F. Iie~np: M&apos;ryari Iron-ore Dcposi(s. Trans. (1915) 61, 3. C. K. Leith 2nd N. J. Mead: Additional Data on Origin of Lateritic Iron 01cs or Eastern Cubn. Tmns. (1916) 63, 75.

Jan 1, 1923

INTRODUCTION Conditions for formation of porphyry copper deposits appear to have been propitious in the Appalachian orogen from the end of Precambrian into Middle Ordovician, and again from Middle Devonian into Mississippian. In the Appalachians we can now record the evolution of a porphyry copper province within a developing orogen, one that reached metamorphic and structural maturity by the end of Devonian. Fig. 15, after Irwin and Coleman (1972), locates that portion of the Appalachian orogen included in this study, and Fig. 16 illustrates general geology of the area. Deposits mentioned in Table 3 and in the text are shown in Fig. 16. Data presented summarize personal observations by the author, published descriptions of specific areas noted in the bibliography, and abstracts from Provincial assessment files. Sources of previously published data are acknowledged. Few comprehensive descriptions of individual porphyry copper deposits in this area exist, so much of the data presented is new to the literature. Porphyry mineralization has, for this chapter, been restricted to porphyry copper de- posits, although porphyry molybdenum de- posits (Clark, 1972) are also shown in Fig. 16 (Hollister, et al., 1974). Copper- molybdenum and tungsten-molybdenum skarns are also omitted to simplify discu sion, though each is known in the area studied. Gaspe Copper is included, however; min- eralization in this deposit is present in the intrusion as well as in the skarn adjacent (Bell and Scott, 1954). Porphyry deposits listed in Table 3 are included because of some important feature, although other deposits have been reported (e.g., Kirkham and Soregaroli, 1975 ) . Clearly, no table now compiled could be complete. The pace of exploration insures that new occurrences will probably be found. Summaries of features exhibited by intrusions shown in Table 3 should remain valid, however, since they appear representative and are based on an adequate number of deposits in the area studied. Paleozoic porphyry copper prospects (shown in Fig. 16) are more common, apparently, in the northeastern part of the orogen, rarely having been found south of Catheart or west of the Logan Line. Occurrences of molybdenum and other associated lithophile elements are, however, known to the south and west as well as further north. Killeen and Newman (1965), King (1970),

Jan 1, 1978

By Philip D. Wilson

The mines of the Calumet & Arizona Mining Co. are situated in the Warren Mining District, Cochise County, Arizona, between Bisbee and Warren and adjoin those of the Copper Queen Consolidated Mining Co. and the Shattuck Arizona Copper Co. Paleozoic 1imestones.of considerable thickness have been intruded by granite porphyry. A great stock of the intrusive outcrops boldly near the city of Bisbee and is known as Sacramento Hill. From this central core the porphyry has tongued out into the limestone for many thousands of feet as dikes and sills of irregular shape and variable dimensions. Churn drilling has recently developed a large tonnage of secondarily enriched copper ore in the main porphyry mass of Sacramento Hill. While some ore has been found in porphyry in other parts of the district, it is relatively unimportant compared with that which occurs in the Paleozoic limestone as irregular lenses replacing favorable beds near porphyry contacts or associated with well-marked fracture zones often many hundreds of feet away from the intrusive. In a zone extending from Sacramento Hill for a distance of from 1,500 to 3,000 ft., the limestone has been extensively metamorphosed and in this contact metamorphic zone the ore occurs through a known vertical thickness of upward of 900 ft. and individual orebodies often show extension in a vertical direction of over 200 ft. At a greater distance from the intrusive stock, the ore occurs as lenses of greater horizontal than vertical dimensions with an average thickness of approximately 30 ft. An exception to this rule is found in the occasional steeply dipping mineralized fractures, almost true tabular veins, which are found long distances a way from the zone of contact metamorphism. The copper was probably introduced during or slightly later than the porphyry intrusion in the form of chalcopyrite and bornite. These primary copper minerals are always associated with pyrite and often occur as rich lenses in a huge mass or shell of pyrite carrying an insignificant percentage of copper. In many instances the copper-bearing solutions were preceded by siliceous solutions and these latter, often persisting during the period of mineralization, have thoroughly indurated the ore-

Jan 1, 1917

By B. W. Gandrud

WET-PROCESS coal-washing tables as we know them today have been in use in this country for approximately 25 years. The literature records only a few table installations worthy of note prior to adoption of the present-day differential-motion table. According to Phillip,1 six Campbell bumping tables were being operated by the St. Bernard Coal Co., Earlington, Ky., in 1893. As late as 1923, according to Richardson, 2 such tables were in operation in the Rosedale washery of the Cambria Steel Co., at Johnstown, Pa. Bumping tables probably were not used to any considerable extent except in the plant at Earlington, and at two or three plants in Pennsylvania, but they may be considered as. forerunners of the present-day coal-washing table. The transition from bumping tables to the type of tables now in use signalized a revolutionary change in table design. The advantages of the new design over the old were so outstanding as to make its adoption inevitable. BUMPING TABLES Bumping tables, as the name implies, utilized a bumping action for conveying the refuse and discharging it over the refuse end. The tables were hung from rods attached to overhead supporting beams. A shaft and cam arrangement at one end of the table served as the actuating mechanism and imparted to the table an endwise, back-and-forth, swinging motion. A bumping block was fixed in the proper position at the shaft end, so that the table would strike against it at the end of each backward swing. The hanger rods or stirrups were so adjusted as to give the table a slight uphill slope toward the refuse end; that is, the end next to the driving mechanism. The feed box was near the upper end of the table and designed to spread the mixture of coal and water over the width of the table. Wash water was added a short distance below the feed box. With the table in motion and coal mixed kith water being fed to it through the feed box, a certain amount of stratification took place, depositing heavy refuse at the bottom of the bed in contact with the surface of the table. Constant bumping and a certain amount

Jan 1, 1950

By G. R. St. Pierre, L. M. Adelsberg, R. Speiser

The rate of scale fot&apos;~I~ti0n on tantalum held in H20-Hz-Ar gns mixtures at temperatures between 840" and 1250°C is related to gas composition and ternpevature. It is found that water vapor partial pressure determines the oxidation rate at a given temperature and that the oxygen potential as fixed by the water vapor to hydrogen ratio Ins no significant effect on the oxidation rate. The Ta205 scale formed during oxidation is composed of an inner lattice-dijf~ision barrier and an outer layer of- cracked/porous oxide 1 HE oxidation of tantalum at temperatures less than 800°C is characterized by solution of oxygen into the metal,&apos;-&apos; the formation and growth of suboxides into the metal,&apos;)2~10-15 and the delayed nucleation of the highest oxide, Above 800°C, Ta205 is found to nucleate rapidly10, 11, 15, 16 except at low oxygen pressures:15 however, there is uncertainty regarding which does not retard the oxidation process. For each gas con~position and temperature investigated, the oxidatioz rate becomes constant after a short adjustment period. It is shozm that a constant oxidation rate nzay pre~?ail even though the tlzickness of the inner lattice-dijjitsion layer of Ta205 is clanging. TFze initial czcrz!ature of the typical &apos;Paralinear" oxidation curve may result froprz causes other than an increasing thickness of tlze inner protective layer. the detailed mechanisms of the high-temperature oxidation. Peterson, Fassell, and wadsworth17 observed linear oxidation behavior for tantalum in oxygen at temperatures between 600" and 1000°C. They reported that equilibrium adsorption of 0, occurs on a surface prior to the rate-deter mining step of the reaction. Cowgill and stringer1&apos; confirmed the observations of Peterson and his coworkers. They stated that the rate-determining step of the reaction could be either the incorporation of adsorbed oxygen into the anion lattice or the dissociation of 0, at the gas-oxide interface. The relative rates of the two surface reactions were proposed to be dependent upon the reaction temperature and the oxygen pressure. stringerlo subsequently reported that the reaction surface is located somewhere

Jan 1, 1968

By C. K. Stoddard, R. G. Knickerbocker, E. T. Leidigh, R. R. Lloyd, K. L. Mattingly

During July 1941, a study was initiated at the Boulder City Experiment Station of the Bureau of Mines on proposed methods for the production of magnesium metal. The major emphasis was placed upon development of a process that required minimum reliance upon the sale or utilization of by-products to meet economic competition from processes already in operation. It was felt that only through the development of such a process could the nation&apos;s vast resources of dolomite and low-grade magnesite that are contiguous to large blocks of firm power be properly utilized. During the course of exploratory tests on electrolytic and electrothermic processes, it was noted that fused magnesium chloride would dissolve appreciable quantities of magnesium oxide in the presence of small amounts of boric oxide. The use of such a solution in an electrolytic cell employing a graphite anode and a steel cathode caused the deposition of magnesium at the cathode and the evolution of carbon oxides at the anode with minimal amounts of chlorine The original results were sufficiently encouraging to justify further investigation on an enlarged scale, since the process seemed to present advantages over other proposed processes.1,2 for the direct use of magnesium oxide in a fused chloride electrolyte. When work oil a larger scale was initiated it was found that the addition of boric oxide to the electrolyte resulted in dispersion of metal and constantly decreasing current efficiency. However, by this time solubility studies had shown that magnesium oxide was sufficiently soluble in magnesium chloride melts containing no boric oxide to effect the same anode reactions, and development work was continued. Over two years of development work have been carried out, and considerable work remains to be done. It is desired to emphasize the fact that many of the difficulties met require a long period of continuous operation before they become serious enough to affect operation of the cell. ACKNOWLEDGMENTS This paper is one of many reporting on various aspects of the Bureau of Mines&apos; program initiated in August 1939 by passage of the Strategic Minerals Act the scope of which was greatly expanded by subsequent legislation. Some of these papers are published as war minerals reports. others as bulletins, technical papers, reports of investigations

Jan 1, 1949

By Don B. Shupe, John K. Berry

The handling and disposal of mine water is a much larger problem than is apparent at first glance. Many more tons of water are removed from underground coal mines in the United States each year than tons of coal. In the old anthracite region of Pennsylvania the average was around 32.7 t (36 st) of water for each ton of coal produced, while bituminous mines average about 4.5 or 5.4 t (5 or 6 st). Water encountered in the mines may come from several different sources. In mines with light cover and without a firm solid roof, rain may seep directly into the workings. This is also true of deeper mines where pillar falls have broken the roof to the surface. The top under creek beds is generally faulty and broken and water comes through the roof at this point. Deeper mines are frequently overlain by water-bearing strata and pillar breaks and faulty top can admit water, while places running to the dip often accumulate water which comes up through the bottom. In all cases, except where passing under a year-round stream, the amount of water made is usually pretty closely connected with the weather-more water during the rainy season, less in the dry, although the deeper a nine is, the longer it is before changes in rainfall are felt. Another source of water, not connected with seasonal changes, is old water, accumulated over a period of time in abandoned workings of the mine, or from flooded adjacent mines. Here the water filters through the coal, the parting, or comes up through cracks in the bottom. Similarly, core holes, drilled to prospect the property, can be a source of unexpected water and modern safety requirements for dust-allaying water at the working faces can turn a pleasant working area into a soggy mess over the weekend if the system is not properly maintained and operated. Why water must be disposed of is obvious. If allowed to accumulate, sooner or later the mine will fill up, or at least it will become "roofed" in low places, blocking ventilation and traffic. It must be controlled long before it reaches this stage. Water standing in the working faces is

Jan 1, 1981

By C. K. Stoddard, R. G. Knickerbocker, E. T. Leidigh, R. R. Lloyd, K. L. Mattingly

DURING July 1941, a study was initiated at the Boulder City Experiment Station of the Bureau of Mines on proposed methods for the production of magnesium metal. The major emphasis was placed upon development of a process that required minimum reliance upon the sale or utilization of by-products to meet economic competition from processes already in operation. It was felt that only through the development of such a process could the nation&apos;s vast resources of dolomite and low-grade magnesite that are contiguous to large blocks of firm power be properly utilized. During the course of exploratory tests on electrolytic and electrothermic processes, it was noted that fused magnesium chloride would dissolve appreciable quantities of magnesium oxide in the presence of small amounts of boric oxide. The use of such a solution in an electrolytic cell employing a graphite anode and a steel cathode caused the deposition of magnesium at the cathode and the evolution of carbon oxides at the anode with minimal amounts of chlorine The original results were sufficiently encouraging to justify further investigation on an enlarged scale, since the process seemed to present advantages over other proposed processes 1.2 for the direct use of magnesium oxide in a fused chloride electrolyte. When work on a larger scale was initiated it was found that the addition of boric oxide to the electrolyte resulted in dispersion of metal and constantly decreasing current efficiency. However, by this time solubility studies had shown that magnesium oxide was sufficiently soluble in magnesium chloride melts containing no boric oxide to effect the same anode reactions, and development work was continued. Over two years of development work have been carried out, and considerable work remains to be done. It is desired to emphasize the fact that many of the difficulties met require a long period of continuous operation before they become serious enough to affect operation of the cell. ACKNOWLEDGMENTS This paper is one of many reporting on various aspects of the Bureau of Mines&apos; program initiated in August 1939 by passage of the Strategic Minerals Act the scope of which was greatly expanded by subsequent legislation. Some of these papers are published as war minerals reports. others as bulletins, technical papers, reports of investigations

Jan 1, 1945

By Wheeler P. Davey

In an article in the General Electric Review, January, 1915, reference was made to the X-ray examination of a steel casting 9/16 in thick. Fig. 1 shows one of the radiographs thus obtained. All these radiographs showed plainly the tool marks on the surface of the casting. All but one showed peculiar markings the shape of which strongly suggested that they were indeed the pictures of holes in the interior. A circular piece, 1 in. in diameter, was punched from the casting at a point where the radiograph shown in Fig. 1 indicated that a blow-hole should be found. (Location of sample shown by circle in Fig. l.) Fig. 2 is a photograph of the end of the punching, showing the hole that was found. Since that article was written it has seemed desirable: (1) to obtain data from which the exposure necessary for any thickness of steel could be at once calculated; (2) to find the thickness of the smallest air inclusion which could be radiographed in a given thickness of steel; (3) to determine in what direction to hope for further progress; and (4) to develop the technique of radiographing metals. In order to gain some preliminary data, several pieces of 1/2-in. (12.5-mm.) boiler plate were obtained, 5 by 7 in. (12.5 by 17.5 cm.) in size. In one of these, holes were drilled in such a way that the axis of each hole was midway between the faces of the steel and parallel to those faces. The diameters of these holes were as follows: Hole number Diameter I.........................................1/4 in. =6.3 mm 2........................................1/8 in. =3.l mm. 3................................... 1/16 in. = 1.6mm. 4....................................... 1/32 in. = 0.8 mm. 5........................................1/64 in. = 0.4 mm. Exposures were made on Seed X-ray plates at 20 in. (50 cm.) distance with Coolidge tube X-117, operated on Scheidel-Western induction coil with mercury turbine break. The X-ray plate was placed on a sheet of 1/8in. (3.1-mm.) lead. The steel was placed above this and a Iead

Jan 1, 1916

By Donald F. Irwin

Amid the violent economic changes of recent years that have affected Canadian gold-mining operations so deeply, the discovery and early developments of Kirkland Lake might easily be overlooked. There was more than one "false dawn" for the district before developments finally established the fact of a superb mineralized zone extending through the present operating properties. Never far from the railway, Kirkland Lake has had the benefit of direct rail service for many years. The pioneer discovery on which the first mill and cyanide plant was erected was the "Tough-Oakes," this property being on what is now the eastern end of the producing area; some time later, the "Lake Shore" was discovered at the present center of the district, and a small plant was built upon it also. Both of these early treatment plants were of pre-war design. Progress in gold metallurgy has caused a gradual change in cyanide practice since the early days at Kirkland Lake, which may be observed in the various plants now operating there. From the beginning, it was recognized that Kirkland Lake ores were more responsive to cyanidation than to alternative recovery methods, and that their mineralization contained gold in very finely divided form. Although sulfides and tellurides are present, the quantity is small, being in the order of 1 or 2 per cent by weight, so that gravity concentration is undesirable, since gold is not confined to the sulfides. Some complication is offered by the presence of tellurides, which have caused lengthy controversy over their importance in recovery methods, but which are now generally regarded as less harmful in the light of increasingly high recoveries being obtained. Nevertheless, finely divided gold intimately associated with sulfides in the presence of tellurides; and occurring in the hard Kirkland Lake porphyry ore, substantially free from natural slime-forming constituents, indicates fine grinding. This has been the universal practice although the degree of grinding has varied a little among the different mills and is considerably finer now than formerly. The natural condition as outlined caused the establishment of fine grinding at an early stage in the development of Kirkland Lake, during the period of valuation of gold at, $20.67 per ounce. With the arrival

Jan 1, 1935

By A. R. Rosenfield, G. T. Hahn

The effects of adding 0.025 volume fraction of uniformly dispersed Tho2, particles (particle size -380A) to iron have been examined. The two-phase alloy is shown to have a lower transition temperature and higher cleavage stress than either the base metal or a solid-solution alloy (Fe-3Si). Enhanced cleavage resistance is thought to be a consequence of particles limiting the effective slip distance of dislocations and thus the ability of Pile-ups to act as stress concentrations. Further calculations predict that the highest cleavage strengths are attained with uniform dispersions, where the particle size is kept small (-250A) and the volume fraction is relatively large (-2 to 3 pct). ALTHOUGH a fine dispersion of second-phase particles is known to impart strength to an alloy, the possibility that it might also impart ductility has only recently been explored. Outstanding progress has been made in the production of ductile tungsten alloys containing Tho21,2or (Hf, Zr)C,= but the contribution of the dispersion to ductility has neither been optimized nor fully analyzed. The basis for such an analysis has now been developed1,5 and is discussed briefly below. Experiments on iron are also described that attempt to isolate one of the possible ductilizing mechanisms and test its effectiveness. In analyzing these experiments, it is important to remember that cleavage obeys a stress criterion, and that either a lower ductile-to-brittle transition temperature or a higher cleavage stress is evidence of enhanced resistance to cleavage. DUCTILIZING MECHANISMS Slip Blockage. Cleavage fracture of polycrystals may be initiated at the intersection of a slip band (or twin) and a neighboring grain or a large (-1 to 5 µ) particle. The slip band generates a stress concentration at its head, and either the grain boundary fractures, the particle fractures, or cleavage is initiated in a neighboring grain. Experimental evidence for this viewpoint is found in metallographic studies8-8 and from the observation that cleavage is usually preceded by yielding.8-11 The potency of a slip band as a stress concentrator

Jan 1, 1968

By J. W. Gwinn

The underground haulage system in the lead-silver mine of the Bunker Hill & Sullivan Co., situated at Kellogg, Idaho, is the most extensive in the Cæur d&apos;Alene district, comprising about 35,000 ft. of tunnels, drifts, and cross-cuts where locomotive haulage is in use. The main working adit, known as the Kellogg tunnel, or No. 9 level, is approximately 10,000 ft. in length from the portal to the main working shaft and extends beyond that about 4,500 ft. in each of two directions. On this level all the ore from the Bunker Hill & Sullivan, the Sierra Nevada Consolidated, and the Caledonia Mining Co.—an average of 44,600 tons per month—is hauled to the mills, located a short distance from the portal. Electric haulage by the trolley-type locomotive is used on this level throughout. Below this level, at intervals of 200 ft. vertically, are five other working levels (Nos. 10, 11,12,13, and 14); and the total haulage distance on these, where electric locomotives are used, is approximately 16,000 ft. No. 13 level has but recently been opened up and is not working to capacity; while the main cross-cut on No. 14 has just been started, and has no need of power haulage. Of the four levels equipped with electric haulage, Nos. 11, 12, and 13 have storage-battery locomotives, and No. 10 still retains the trolley type by reason of the small and decreasing tonnage produced. Electrification - Electric power is supplied to the mine by two systems. The first, the 500-volt direct-current trolley, was installed in 1897 when the Kellogg tunnel was started, and was extended as the tunnel advanced, being used for the first trainload of ore on Nov. 17, 1902, since which time it has been in continuous service. The current for the line is transmitted on a No. 00 copper wire as far as the shaft, and on No. 0 wire throughout the remaining length of the Kellogg tunnel; and until the installation of the storage-battery locomotives it was used in practically all the cross-cuts and drifts on each level below No. 9.

Jan 1, 1915

By A. L. Holley

The first session was held in the rooms of the American Philosophical Society, on Tuesday evening, February 26th. The President, Dr. T. Sterry Hunt, called the meeting to order, and after a few introductory remarks concerning the importance of theoretical and speculative science, which often involves principles of the highest economic value, and, more than all that, serves to enlarge our conceptions of the universe, and ennoble us, by the cultivation which it affords to our most exalted faculties, proceeded to discuss some points in the chemistry of the atmosphere. It is known that there is in the crust of the earth a great amount of oxidized carbon, not only in the shape of coal, but also in the graphite or plunlbago of the crystalline rocks, in the various bituminous shales or pyroschists, which are found in all succeeding rock-formations, and also in the forms of bitumen and petroleum. All the analogies of nature lead us to conclude that these various carbonaceous substances have had an organic origin, and have been generated by the deoxidation of carbonic acid, a process effected by the growing plant, and attended with the liberation of oxygen. He showed that the carbon of a layer of coal covering the whole earth&apos;s surface to the thickness of one meter, would, in its production from carbonic dioxide, liberate an amount of oxygen equal to that now present in our atmosphere. But bituminous coal contains also a large amount of hydrogen, derived from the deoxidation of water, which implies the liberation of a farther portion of oxygen. The amount from this latter source would equal, for the various coals and asphalts, from one-eighth to one-fourth, and, for the petroleums, onehalf of that set free in the deoxidation of the carbon which these hydrocarbonaceous bodies contain. From what we know of the composition of the stratified rocks, it is probable that they include an amount of deoxidized carbon and hydrogen many times greater than that contained in a layer of coal one meter in thickness, and, consequently, that the disengaged oxygen in past ages must have far exceeded that now present in our atmosphere. To this must be added

Jan 1, 1879