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SULPHUR is a very well known mineral and apparently is produced in many places. It is engendered from an unctuous earthy and powerfully hot substance so that it is considered among experienced workers to bear a resemblance to the element of fire. This is called by these same men the masculine seed and the prime agent of Nature in the composition of metals. Because of its great dryness and heat it has, as experience shows, affinity with fire, which is easily introduced in it when brought near. And once introduced the fire is quenched only with difficulty before its unctuousness is wholly consumed. Although it shows itself to us of such a hot and dry nature, we must not think that sulphur is a substance so pure that it can stand by itself or that in order to attain its form it has no need of its portion and part of moisture like every other mixture. This is shown to us by its easy fusion, in which it resembles the metals. This thing is found in many places and in many varieties of color; some are white, others yellow and orange, and some others between gray and black. They also say that some red is found. It does not occur in that arrangement of veins like other minerals, but most liberal Nature makes whole mountains of it as is seen in the Aeolian islands, [26] near Sicily, in Etna or Moncibello which is the island of Sicily, at Pozzuoli, in the territory of Rome, in the Sienese domain at San Filippo, and in many other similar places. It is a substance that has a very strong odor and is most unpleasant to smell. It is very fixed in its substance so that it is never corrupted by time, by boiling, or by the moisture of water. For although it may stand in water a long time it never becomes soft nor does it ever decrease or increase in weight. It is brittle and easily crushed very fine. It is said that a trace of garlic rubbed on the mortar helps anyone who wishes to reduce it to impalpability. Its ores have a form more like earth than like stone although they some¬times have the color of a certain soft rock. The places where it is found are easily recognized by the great odor that they give out and by the very hot baths that often spring forth near it. What I have already told you about quicksilver that is contrary to the

Jan 1, 1942

By Edmund S. Davenport

The production of thorium of high purity by the Ca-CaCl2 reduction has been described by Marden and Rentschler,1 who also reported some of the properties of the coherent, ductile metal obtained from this pure thorium powder. The present paper describes the properties of thorium produced by the Ca-CaCl2 process modified in some details to meet commercial conditions. The principal effect of these changes in process has been an unavoidable increase in the oxide content of the thorium. Materials and Methods The thorium employed in this investigation was made from pure thorium oxide (ThO2) by the Ca-CaCl2 reduction. The washed and dried metal powder was pressed into bars approximately 0.160 in. dia. and 10 in. long, at a pressure of 75,000 Ib. per sq. in. The bars were heat-treated in vacuum at 1175' C. for 1 hr. This treatment yielded ingots sufficiently dense and coherent for mechanical working. Thorium has been successfully worked without a protective metallic covering, but for the purposes of this investigation it was more convenient to inclose the ingots in soft iron tubes and swage or roll cold to the desired sizes. The iron sheath was dissolved with nitric acid, leaving the cold-worked thorium exposed. Chemical Analyses Analyses of typical samples of the material used in this work arc given in Table 1. Thorium powder oxidizes in moist air, even at room temperature; no unusual precautions were taken to prevent such oxidation of the material used in this investigation. A certain amount of oxidation probably takes place during pressing; certainly during heat-treating unless a very slow heating schedule is employed. These factors account

Jan 1, 1930

APRIL 10-Officially, spring comes to the Great Lakes on March 21 as it does elsewhere in the country but in the Superior district continued snow and freezing until late in March have caused citizens in Duluth to place their bets on April 15 for the first ore vessels if the ice breakup is left to Mother Nature. North and west of Duluth and near the eastern end of the Mesabilies the little town of Aurora, population 1100. As the little v-nosed snowplow, pride of the community, shuttled back and forth clearing Aurora's few sidewalks, the crowd in Bradich's Cafe were more interested in the impending high school state championship basketball tournament in Minneapolis than in the outcome of Erie Mining Company's petition for water rights for their proposed 10 million ton taconite concentrating plant. Such a plant would employ 4500 workmen, and at the prevailing ratio of 10 people for every mine worker in Minnesota, this would mean a 45,000 increase in population for Aurora and the vicinity in the next few years. Downstate fishermen are alarmed at the flurry of activity by the mining companies in pushing plans for large scale recovery of iron from taconite. Inconvenience to these gentlemen will be inconsequential when compared with the vast increase in payrolls for range communities. Oliver is pushing the construction of a fine ore agglomeration plant at Virginia which will give them valuable experience for projected taconite processing. Oglebay, Norton & Co. is ready to go at Beaver Bay, north of Duluth, as the right of way for a railroad from Babitt to Beaver Bay is secured as well as permission to dispose of tailing into Lake Superior at the site of the proposed concentrating plant. This company is also doing research in agglomeration at Ashland, Ky., in cooperation with other interests. The financing is yet to be worked out. Of the four possibilities for agglomerating taconite concentrate-sintering, pellitizing, nodulizing and briquetting-the prospects for pelletizing appear the most favorable., It seems likely that 60 cents per ton can be saved by this process over sintering because only 1 to 2 pct of coal is required as compared with 7 pct for sintering. One reason for the lower coal consumption is that the chemical transition of magnetite to hematite which transpires in the pelletizing process is exothermic.

Jan 5, 1950

By Hallet R. Robbins

KOREA, the ancient " Hermit Kingdom," is a peninsula jutting out from the coast of eastern Asia. By the natives it is called " Chosen," which, translated, means " Land of the Morning Calm." It lies between the Yellow sea and the Sea of Japan. On the north it is separated from Manchuria and the Russian province of Primorsk by the Yalu and Tiumen rivers ; on the south the Korean straits interpose a rough voyage of 120 miles to the nearest point in Japan. The entire country is situated between the parallels of 34° and 42° N. latitude. The surface of the country is made up of successive ranges of unglaciated mountains, separated by narrow, fertile, and more or less densely populated, valleys. Through all the obscure centuries of its history, Korea has succeeded in maintaining a monastic seclusion, over which, from time immemorial until the late Chino-Japanese war in 1894, China exercised a shadowy sovereignty. Although Korea had been forced into slight foreign contact previously, her first foreign treaty was signed with Japan in 1876. Under the restraining guardianship of China, the Japanese treaty bore but insignificant innovations for Korea; but when, in 1883, a treaty was made with the United States, the first of the western nations, a decade after the American gunboats, under Commodore Rodgers and Lieutenant Schley, forced their way up the Salee river, shooting daylight through the ancient walls and fastnesses, Korea awoke from her sleep of 4,000 years. The Korean peninsula suddenly became the arena where rival nations' enterprises and individuals met in fiercest conflict. Out of this struggle grew two singularly successful American

Jan 7, 1908

By J. T. Norton, N. J. Grant, I. S., Servi

Coarse grained high purity aluminum was tested in creep at temperatures of 400° to 1200°F to develop subgrain structures. Measurements of subgrain size, distribution, and rotation were made from X-ray diffraction patterns. Subgrain size and distribution were checked metallographically and the size was compared with average slip band spacing. The slip family was determined for several specimens. THE interest and research recently evident abroad in the role of subgrain formation and polygon-ization as a contribution to the creep of metals at elevated temperatures is deserving of greater attention in this country. Such metallic subgrains can be defined as macroblocks existing within the grains. The general observation has been that the macro-blocks which belong to the same grain have a maximum difference in orientation of a few degrees. In spite of the considerable amount of work that has been done since Jenkins and Mellorl observed the "division of existing crystals into smaller units when deformation occurs at an annealing temperature," the subject of subgrain formation is only now receiving truly active discussion and investigation. The existence of subgrains has been revealed by metallographic methods, as in the work of Jenkins and Mellor,1 and by X-ray methods, first applied to this problem by Homes.' Hirst3 and Calnan and Burns4 applied the back-reflection Laue technique to the study of coarse grained specimens. Wood et al.5 and Greenough and Smith' examined the ring obtained with a back-reflection camera for the study of fine grained specimens. In addition to the above, the transmission technique was used by Wood.6 A special technique was developed by Guinier and Tennevin8 in order to improve the resolution. Metallographically, the subgrains have been observed directly on the surface of deformed specimens by Wood et al.,3 or have been made evident on repolished surfaces by applying a suitable etching reagent. The latter technique, first suggested by Lacombe and Beaujard,9 was then improved by Wyon and Crussard.10 Subgrains can be formed in single crystals after small amounts of bending followed by heating after this cold work, or during deformation at elevated temperatures. The first phenomenon was analyzed by Cahn11 for the simple case of pure bending followed by annealing. Cahn suggested a mechanism of subgrain formation based on the dislocation theory and called this phenomenon "polygonization." He extended this mechanism to the more complex case of local bending, such as the bending which may occur when a polycrystalline specimen is deformed in tension. Cahn's suggestion was later found quite consistent with the results obtained by Dunn and Daniels." An explanation has been presented recently regarding the formation of subgrains during deformation at elevated temperatures by Chang and Grant.'" In general, there are two schools of thought on the subject. One, according to Wood et al.,5 is that subgrain formation is a mechanism of deformation which is operative under certain conditions in the same way that the slip process is the mechanism of deformation which is operative under other conditions. The boundaries between the subgrains undergo a viscous flow which contributes substantially to the deformation of the material. The second, according to Cahn,13 Wyon and Crussard,10 and Chang and Grant,18 is that subgrain formation is the effect of simultaneous deformation and annealing and is,

Jan 1, 1953

By William I. Gardner

Optimum design of a structure obviously requires a thorough knowledge of the materials to be utilized in its construction. When the structure is a tunnel, a most important element in its design and construction is the geology. As a tunnel may be many miles in length and at depths of hundreds or thousands of feet, we face a real problem to meet the needs of the designer and builder. How can we determine the properties of our construction materials in this situation? Engineering geology has had a formidable challenge to meet the requirements of conventional excavation methods; the advent of machine methods for rapid excavation compounds the requirements for more detailed and more precise geological knowledge of the tunnel site. This chapter will discuss the means now at our disposal to meet the challenge to produce the required data on the tunnel site in the preconstruction stage. Our considerations will be directed towards construction of a free-flow tunnel, primarily in fractured rock formations, without any requirements for the rock mechanics type of in-situ tests that might be made for a pressure tunnel or for a large opening for an underground power plant. In essence the investigation must determine: (1) The geologic conditions affecting the type of construction equipment and excavation method of the rock to be broken and removed. (2) The quantities of water and gas to be encountered. (3) The strength and stability of the material surrounding the bore and its need for support and lining. GEOLOGICAL FACTORS AFFECTING TUNNEL DESIGN AND CONSTRUCTION The engineer or contractor may classify the rock as either competent or incompetent or more pointedly as "good" or "bad" ground. The geologist may bestow a precise petrographic name upon the rock, such as granodiorite or indurated tuff breccia or name the formation, as Mancos shale, for

Jan 1, 1970

By W. J., Kroll

MOST people believe that rare metals are always, scarce in nature, expensive to make, and therefore useless despite some miraculous properties which might make them a cure-all. There are' some metals, which are quite frequent in nature, such as zirconium, which are called rare only because our present methods for making them are elaborate, thus forcing the manufacturer to sell them at a high price. There are also truly rare metals, such as gallium, which do not occur frequently in ores, but are easily reducible from their oxides. In these cases the price of the concentration operation is the decisive factor. The distribution of the elements in the earth's crust is no indication as to the availability of a metal; the concentration operation is the critical factor. Concentration is frequently obtained in the course of metallurgical operations for the extraction of other metals, and the rare metal may be enriched in by-products, flue dusts, mother liquors or precipitates from electrolyte purification as are indium, thallium, selenium, and tellurium. A periodic table of the rare elements may serve as a basis for discussion of their properties and to establish a program. (Table 1.)

Jan 1, 1946

By Haydn H. Murray, Sam H. Patterson

The term "clay" is somewhat ambiguous un¬less specifically defined, because it is used in three ways: (1) as a diverse group of fine-¬grained minerals, (2) as a rock term, and (3) as a particle-size term. Actually, most persons using the term "clay" realize that it has several meanings, and in most instances they define it. As a rock term, clay is difficult to define be¬cause of the wide variety of materials that com¬pose it; therefore, the definition must be gen¬eral. Clay is a natural earthy, fine-grained ma¬terial composed largely of a group of crystalline minerals known as the clay minerals. These minerals are hydrous silicates composed mainly of silica, alumina, and water. Several of these minerals also contain appreciable quantities of iron, alkalies, and alkaline earths. Many defini¬tions state that a clay is plastic when wet. Most clay materials do have this property, but some clays are not plastic; for example, halloysite and flint clay. As a particle-size term, clay is used for the category that includes the smallest particles. The maximum-size particles in the clay-size grade are defined differently on various grade scales, Soil investigators and mineralogists gen¬erally use 2 micrometers as the maximum size, whereas the widely used scale by Wentworth (1922) defines clay as material finer than ap¬proximately 4 micrometers. Some authorities find it convenient to use the term "clay" for any fine-grained, natural, earthy, argillaceous material (Grim, 1968). When used this way, the term includes clay, shale, or ar¬gillite, and some argillaceous soils. Even though no standard definition of the term clay is accepted by geologists, agronomists, engineers, and others, the term is generally un¬derstood by those who use it. Clay is an abun¬dant natural raw material, and it has an amaz¬ing variety of uses and properties which will be discussed in this chapter. Clays rank among the leading industrial min¬erals in both tonnages produced and total value. Their importance is indicated in Table 1, which lists the 1970, 1971, and 1972 production and values according to the U.S. Bureau of Mines (Ampian, 1972). Adequate reliable statistical data on which to summarize world production of clay are un¬available; this paragraph outlines the world re¬quirements for clay only in a very general way. According to one estimate, the world bentonite production in 1972 was 3.5 million tons (Anon., 1973a), but in the authors' opinion it was prob¬ably at least 5 million tons. The total fuller's earth produced was at least 1.5 million tons and may have been as much as 2 million tons. The total world kaolin production in 1972 was more than 10 million tons. Approximately 7 million tons of this total was produced in only two regions-the Georgia-South Carolina kaolin belt in the United States and the Cornwall re¬gion, United Kingdom. The world's 1972 out¬put of ball clay, which is also produced pri¬marily in the United States and the United Kingdom, was approximately 1.5 million tons or perhaps a little more. The total world fire clay production in 1972 was probably about one and one-half to two times and the miscellaneous clay production three times the United States production. As industrial minerals, clays are a complex group that consists of several mineral commodi¬ties, each having somewhat different mineral¬ogy, geologic occurrence, technology, and uses. In this chapter these commodities are organized

Jan 1, 1975

By Wm. E. Milligan

LEAD stocks at the beginning of 1943 were comfortable when compared with those of other base metals such as copper, zinc and tin. This situation was early recognized by W.P.B. and other Governmental agencies and every effort was made to encourage the substitution of lead for these latter metals in all essential uses. Despite this apparently healthy condition, lead was not denied participation in the various measures inaugurated by the Government to relieve metal shortages. Thus in the Mexican trade agreement, effective Jan. 20, the tariff on two important classes of lead importss was halved. Similarly, in the setting up of B quota premiums, a B base was allotted to lead, with all pro¬duction above this figure receiving an additional payment of 2.75c. per lb., or a total payment of 11.75c. per lb. At about the same time it was announced that all quota transactions would be based upon the lead content as shown by the smelter settlement sheets. This basis was 86 percent of the lead content for all ores shipped to custom milling plants and 95 per cent for ores and concentrates shipped to custom smelting plants. The importance of this action can be appreciated when in the Coeur d'Alene it was estimated as equivalent to a 5 per cent increase compared to the previous base.

Jan 1, 1944

By H. G. Moulton

THE INCREASING scale of mining operations over the past decade, particularly in connection with the exploitation of large bodies of comparatively low-grade copper ores, has made necessary the study of the behavior of rock under failure. When extractions of as high as 40,000 tons a day are reached in steam-shovel operations and as high as 20,000 tons per day in underground mining operations, it is evident that excavations soon become of such size that the behavior of the rock will often be dependent on fundamental principles applicable to more or less homogeneous materials under stress, rather than on weathering or local planes of weakness. In the ordinary rock excavations encountered in civil-engineering practice, such as excavations for subways, highways, railroads, etc., rock faces are not carried to depths sufficient to develop any pressures, or consequently any failures, except those due to loose masses resulting from local planes of weakness. When, however, orebodies whose tonnage is measured by hundreds of thousands are to be extracted by steam-shovel operations in open pits, it is necessary to determine if possible in advance the slopes that the sides of the pits will assume, for these slopes influence the shape of the excavations and thereby the amount of ore that may be extracted by the open-pit method. When large orebodies are mined underground at depths of 300 to 500 ft. (91 to 152 m.) by caving methods, the surface subsiding as the ore is withdrawn, it is necessary to determine in advance the outermost limits of fracture in the subsiding surface, for on the delineation of these limits depends the location of surface improvements, mills, smelters, etc. and also the location of development work, such as hoisting shafts, main haulage levels, and all other underground openings that must remain undisturbed during the period of ore extraction. Heretofore, in civil-engineering practice, it has been assumed that earth and rock behave differently in failure. For the calculation of earth

Jan 2, 1920

By John A. Gann

The following investigation constitutes a brief réumé of the more important binary magnesium alloys from the standpoint of metallo-graphic technique, and the effect of heat treatment on structure and properties. The comparative newness of the subject justifies this procedure as a preface to a more detailed study of each individual series of alloys. The work was started with the idea of practical application in the industry rather than as a theoretical investigation. The alloy compositions studied were selected as those most likely to show whether heat treatment would produce beneficial results. Furthermore, it was considered satisfactory to use commercial 99.9 per cent. magnesium, the best commercial grade of alloying ingredients, and to limit the time of heat treatment at the expense of incomplete equilibrium. These facts must be kept in mind when examining the results obtained, and the conclusions drawn. Preparation of Alloys All melts were made in an oil-fired cast-steel pot, approximately 12 in. dia, by 12 in. deep. Approximately 15 lb. of flux and 50 lb. of magnesium were melted and the calculated amount of alloying metal was added. After thorough alloying and puddling, the metal was chill cast in a graphite mold with four 1/2 by 1/2 by 4 in. bars fed from a common sprue and runner. The next higher composition alloy in a given series was made by adding the calculated amount of metal to the heel from the preceding cast. The pot was thoroughly cleaned after each series and new flux then introduced, thus avoiding possible contamination from earlier melts. The percentage compositions given in Table 1 are the calculated values. While not all alloys were analyzed, enough were checked to indicate that the reported compositions are correct to a few tenths of one per cent. A more detailed description of the foundry methods employed has been given in a previous paper. 1

Jan 1, 1929

By John A. Gann

The following investigation constitutes a brief réumé of the more important binary magnesium alloys from the standpoint of metallo-graphic technique, and the effect of heat treatment on structure and properties. The comparative newness of the subject justifies this procedure as a preface to a more detailed study of each individual series of alloys. The work was started with the idea of practical application in the industry rather than as a theoretical investigation. The alloy compositions studied were selected as those most likely to show whether heat treatment would produce beneficial results. Furthermore, it was considered satisfactory to use commercial 99.9 per cent. magnesium, the best commercial grade of alloying ingredients, and to limit the time of heat treatment at the expense of incomplete equilibrium. These facts must be kept in mind when examining the results obtained, and the conclusions drawn. Preparation of Alloys All melts were made in an oil-fired cast-steel pot, approximately 12 in. dia, by 12 in. deep. Approximately 15 lb. of flux and 50 lb. of magnesium were melted and the calculated amount of alloying metal was added. After thorough alloying and puddling, the metal was chill cast in a graphite mold with four 1/2 by 1/2 by 4 in. bars fed from a common sprue and runner. The next higher composition alloy in a given series was made by adding the calculated amount of metal to the heel from the preceding cast. The pot was thoroughly cleaned after each series and new flux then introduced, thus avoiding possible contamination from earlier melts. The percentage compositions given in Table 1 are the calculated values. While not all alloys were analyzed, enough were checked to indicate that the reported compositions are correct to a few tenths of one per cent. A more detailed description of the foundry methods employed has been given in a previous paper. 1

Jan 1, 1929

By C. H. Mathewson

MICROSCOPIC rnetallography has been exploited quite well enough to bring about a very general understanding that the typical metal or alloy is composed of minute crystalline particles blended into a coherent microstructural mosaic. One does not have to be a specialist in metallography to realize that the properties of such an aggregate are essentially a summation in appropriate form of individual effects derived from the shape, size, placement or orientation and cohesive characteristics of the component particles. It is clearly of great importance to consider the various forms of discontinuity which may occur at the boundaries between these crystalline particles. When a number of particles each possessing the same orderly arrangement of atoms are brought together into a close-fitting system of purely haphazard contacts, not unlike a handful of snowflakes compacted into a snowball, the particles are said to possess random orientation. There are no generally accepted views concerning the arrangement of the atomis or the constitutional reaction between atoms where one crystal meets another, but these contact regions are characterized by strength rather than weakness and it is customary to require the presence of many rather than few boundaries in preparing metal for useful service. Under certain circumstances all of the particles in a metal may be nearly alike in orientation. Other general tendencies of orientation may be associated with particular forms of mechanical and thermal treatment. In contrast with these cases of fortuitous or statistical diversity of orientation, we often find adjacent particles united along a plane which possesses a grouping of atoms belonging equally well to both structures. This, of course, determines a fixed relationship between the two orientations and it is always possible to derive one from the other by some form of rotation or reflection prescribed by the symmetry of the crystal structure under consideration. Particles united in this manner are known as twin crystals although the term refers to the form of association rather than the number of individuals concerned.

By Francis Foley

IN THE first report1 disks of steel of- known composition and history were exposed, under carefully prescribed conditions, to impacts of explosion products resulting from the explosion of 50-gm. charges of explosives having well-determined rates of detonation, or to, impacts of a weight of known mass, falling through measured distances. There were available at the Bureau of Mines Experiment Station five explosives, having rates of detonation of 5716, 4470, 3190, 2296, and 1523 meters per second. It being desired to continue this exposure downward, and no explosives with a lesser rate of detonation being at hand, resort was had to the impact of a falling weight, the differences in the velocity of impact being attained by varying the height from which the weight was allowed to fall. It was expected by this means to demonstrate experimentally that the development of Neumann bands was determined by the suddenness of the deformation of the metal in which they were produced. But while progressive deformations were obtained with the explosive charges, the falling-weight method failed because the tup was progressively deformed, also the disks were so flattened as to be unfit for metallographic examination. A return, therefore, has been made to the use of explosives as the source of energy, an air-gap being interposed between the charge of explosive and the disk, as the effect diminishes as the function of the distance between the charge and the object on which the products of its explosion, or the shock wave from its detonation, impinge. The details of the arrangement of the tests by the air-gap method were the same as those described by Foley and Howell,2 except that after the system had been set up and the desired apparent specific gravity for the explosive

Jan 2, 1926

By F. R. Cattoir, R. W. Kimball, C. T. Anderson

ONE of the principal impurities in all steels is sulphur. Sulphur-bearing, manganese-free steels exhibit hot shortness. Manganese is added to steel to improve the hot-working properties. If no sulphur were present in steel, it is probable that hot shortness would be nonexistent. This paper is the first of a series to be issued by this Laboratory reporting the measurements of hot forgeability tests and the physical properties of Fe-C alloys to which additions of various alloying elements have been made. The present paper describes the results- obtained by the addition of varying amounts of sulphur to Fe-C alloys. To obtain control over residual elements in the various charges melted in the arc furnace, it was considered advantageous to use sponge iron from one source as the melting stock rather than scrap metal having an unknown history. Small amounts of unwanted alloying elements might be introduced into the charge when scrap was used, thereby influencing the results of the various heats. A sponge iron having a high silica-lime ratio was used. Ore from Sunrise, Wyo., had been reduced to sponge iron and briquetted at the Bureau of Mines sponge-iron plant at Laramie, Wyo. The briquettes were 5 in. in diam and 2 to 3 in. in thickness, and weighed about 10 lb each. The chemical analysis of the sponge iron is as follows: C, 0.67 pct; Mn, 0.10; SiO2, 4.75; CaO, 1.4; P, 0.044; S, 0.72; MgO, 0.4; A12O3, 1.1; total Fe, 87.5; Fe metallic, 79.2; and reduction, 90.5 pct. Where a reducing agent was required, crushed graphite electrodes usually were used. The charcoal available contained 0.20 pct S. An analysis of the available coke showed it to contain 0.70 pct S. Where high sulphur heats were required, elemental sulphur additions were made to the ladle. Limestone of good quality was obtained locally and had the following analysis: CaO, 53.7 pct; MgO, 0.8; ignition loss, 42.4; R2O3, 0.2; SiO2, 3.0; and P2O5, 0.014. Melting Procedure Sponge iron was melted to produce metal stock for the experimental alloys in a silica-lined, three-phase, direct-arc, size ST, Moore Rapid Lectromelt furnace with a 500 kva rating. Fig. 1 shows this furnace installation. About 25 tons of sponge iron was melted in 75 heats, averaging 927 lb of sponge iron to the heat. An addition of carbon was required to complete the reduction of a portion of the iron oxide remaining in the sponge to prevent high losses of iron oxide in the slag and a low carbon content in the resulting metal. As reducing agents in preparing the melting stock, charcoal, coke, and a carbon product resulting from the thermal decomposition of natural gas were used. The quantity varied from 20 to 60 Ib per furnace charge, with an average of 38 lb. An average analysis of the metal obtained gave 0.52 pct C, about 0.01 pct Mn, 0.070 pct P, and 0.092 pct S. The average yield of metal was 647 lb with 241 1b of slag, the sponge-iron recovery being 70 pct. The metal obtained in melting the sponge iron was cast into pigs weighing about 20 lb each to facilitate recharging into the furnace for further refining. The pouring of the pigs is shown in Fig. 2. The average power consumption for the production of the 24 tons of metal obtained was 1704 kw-hr per ton.

Jan 1, 1954

By AIME AIME

THE papers on geophysics were roughly divided into two groups*, those presented Monday morning being of a more technical and theoretical nature, whereas the afternoon session was principally taken up with discussions of a predominantly geological flavor. Thus it was made possible for those of a mathematical turn of mind to indulge their penchant for formula and differentials before lunch, leaving the field comparatively free, after lunch, for the geologists to learn of practical applications. The advantage of this classification is evident, and it is to be hoped that in some future meetings it will be possible to hold joint sessions of the geophysicists and mining geologists, to consider the overlap of the two fields.

Jan 1, 1931

By Victor O. Strobel

Fire-brick hot-blast stoves have been the subject of frequent discussions at the meetings of the Institute; and although it is my object to elucidate some of the points in connection with this subject, I will not go into the specific features of all types, but more especially call attention to a new type recently designed by Mr. Fred. W. Gordon. As the economical production of a ton of pig-iron is a more essential feature than a large output, much depends, where fuel cannot be obtained cheaply, upon suitable apparatus whereby high temperatures can be maintained. Where iron-pipe stoves have been employed, the fuel-consumption reached one and a half pounds of fuel, and, when a larger output was desired, often two pounds, to the pound of iron produced. The temperature attained rarely exceeded 900' F., and that at the expense of frequent renewals of the pipes, which was not inconsiderable. The fire-brick hot-blast stoves of the past five or six years have clearly demonstrated their superiority over the old system. Of the accompanying drawings, Fig. 3 illustrates a four-pass regen-

Jan 1, 1886

By Ralph H. Sweetser

N Greenup and Carter counties, in the northeastern part of Kentucky, are the remains of many old charcoal furnaces built and operated during the period from 1818 to 1892. They were all included in what was called the Hanging Rock district. In the summer of 1930 I visited ten of these old blast furnaces, as follows:

Jan 1, 1931

By R. J. Evans

THE Combined Metals Reduction Co.'s plant is at Bauer, Utah. It was built primarily to treat ore from the Combined Metals mine at Pioche, Nevada. Shortly after its completion, the company acquired the old Honerine mine, and ores from this mine, as well as custom ores from widely scattered districts, are now being treated at the Bauer plant. PIOCHE ORE The Pioche ore, which comprises about 50 per cent. of the mill feed, occurs as a replacement of an impure thin-bedded limestone. The lime beddings are separated by thin layers of micaceous shale containing appreciable quantities of sericite and graphite. The ore is an exceptionally fine-grained, dense mixture of minerals and gangue, assaying approximately 0.03 oz. gold, 7.2 oz. silver, 7 per cent. lead, 15 per cent. zinc, 16 per cent. iron, 29 per cent. insoluble and 1.5 per cent. lime. Of the total lead 7 per cent. is in the form of sulfate and carbonate. Approximately 10 per cent. of the ore consists of chert nodules impregnated with barren pyrite; the nodules average 0.8 mm. in size, and are extremely hard, compared with the other constituents of the ore. Microscopic examination of Pioche ore ground to 80 per cent. minus 150 mesh shows pyrite, sphalerite and galena still attached. EARLY ATTEMPTS AT ORE DRESSING Metallurgists, both professional and those working for private companies, have been more or less familiar with the Pioche ore since 1913; in fact, a total of 35 commercial and plant laboratories experimented with the ore between 1913 and 1921. The work during this period was decidedly negative, it being seemingly impossible to effect a satisfactory separation of the valuable minerals into marketable products. In 1913, it was recognized that fine grinding-that is, about minus 200 mesh-was required to liberate the minerals from one another, and from the gangue, but such fine grinding was not considered practicable at this time.

Jan 1, 1928

By Z. T. Bieniawski

Tunneling in coal mines includes driving the main haulageways or roadways which serve as the development entries. Although constituting the lifelines of these mines, little attention has been paid to development entries in the United States in terms of systematic pre-construction planning and design. Coal mine tunnels, as the terminology is used in Europe and elsewhere, are understood in the United States to be the main development entries, either in room-and-pillar mining or in longwall mining. These development entries are not tunnels in the traditional sense since they usually are of a multi-entry type involving entries and cross-cuts, and their intersections. Thus, the design of coal mine tunnels is intertwined with the design of coal pillars. This paper summarizes the results of a three-year research project aimed at improving the design of development entries in U.S. coal mining. A design approach has been developed for this purpose and design procedures for roof support in main entries and for pillar sizing are proposed.

Jan 1, 1984