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By Douglas Bunting

With the gradual exhaustion of the upper veins in the anthracite coal-fields, the problem of mining at greater depths acquires increasing importance and demands the consideration .of a number of important factors, one of which is the greater earth-pressure and the consequent necessity of stronger support for the roof. Under the pillar-and-chamber system, almost exclusively followed in the Northen anthracite-field, the highest economy in mining is generally secured by leaving, on first mining, pillars only sufficient to support safely the overlying strata. As to the necessary size of such pillars, the opinions of mining experts are widely divergent. In establishing the width of chambers and pillars, the thickness of vein and its depth below the surface have received little consideration. For instance, it has been quite usual to work both overlying and underlying veins with the same width of chambers and pillars, when the lower vein was two and one-half times as thick, and twice as far below the surface, as the upper. In view of the generally-accepted theory that the crushing-strength of coal-pillars of the same base-area becomes less with increased height, it is probable, in this instance at least, that the moat economical mining has not been secured. This question of adequate pillar-support is economically less important down to about 800 ft. than at greater depths; and it is with reference to mining at these greater depths that the study of the subject here presented has been prompted. The necessity of leaving larger pillars, involving greater mining-costs per ton and also smaller yields per acre, is one of the troubles of deep working. To mine without leaving adequate pillar-supports will result, sooner or later, in a squeeze. Limited areas, it is true, have been mined at certain widths of

Jan 1, 1912

By P. R. Sperry

Aluminum alloy 3S was examined to determine the relationship between the applicable phase diagram and the microstructures produced under conditions tending toward non-equilibrium as well as equilibrium. The only phases present in the alloy were aluminum, (Mn,Fe)A16, aAI(Mn,Fe)Si, and silicon. It was found that the alloy behaved essentially as though it belonged to the Al-Mn-Si system. The effects of various solidification rates and of various homogenization treatments were studied. Particular attention was given to a nonuniform precipitate distribution which reflected the solute distribution in the cast aluminum solid solution. Some possible explanations for the solute distribution based on characteristics of the Al-Mn-Si or AI-Mn systems were discussed. ALUMINUM alloy 3s (aluminum plus 1.25 pct Mn) is one of the oldest and the most widely used of the wrought aluminum alloys. In spite of this fact, there are some aspects of the metallography of 3s which have not been revealed or which have not been brought to the attention of the metallurgist working with the alloy. The purpose of this investigation was to demonstrate in general how some of the fundamentals of equilibrium phase diagrams may be applied to the study of an alloy and to show specifically the origin of certain metal-lographic features of aluminum alloy 3s. It is hoped that this information can serve as a basis for solving specific problems relating microstructure to such things as mechanical properties, recrystallization, grain growth, and surface finish. Literature Survey Considering that alloy 3s contains only one alloying addition, manganese, it seems reasonable that it would have characteristics pertaining to the A1-Mn system. However, those characteristics might well be altered by the impurities in the commercial alloy, especially iron and silicon. Therefore, not only the simple binary but also more complex systems had to be reviewed. One characteristic of the A1-Mn system worthy of mention is its sluggishness, which leads to conflicting solubility data1,'2 and makes it relatively easy to supersaturate the solid solution and shift the eutectic composition during rapid solidification.3'4 Another characteristic is the strong influence which small amounts of impurities, especially iron, exert in lowering the solid solubility of manganese. Undissolved manganese is ordinarily present in an intermetallic phase, MnAl,, having an orthorhombic crystal structure. A metastable precipitating phase designated as "G" has been reported but small amounts of iron and silicon suppress this phase entirely." Raynor has established that MnA1, can dissolve a considerable amount of iron by a substitution of iron for manganese atoms up to 50 atomic pct.'" Consequently, in the Al-Mn-Fe liquidus diagram, the eutectic valley separating the primary aluminum and (Mn,Fe)Al, fields is fairly close to a constant Mn + Fe content." This is an important consideration in regulating the composition of 3s and also other aluminum alloys with high manganese additions."

Jan 1, 1956

By John C. Calhoun, F. W. Gooch, J. P. Everett

The results of two sets of displacement experiments are reported. In the first set of experiments various solutions of sugar in water were displaced by other solutions of sugar in water. In the second set oils were displaced by water. Each set of experiments was performed on a linear system made of cemented silica sand grains. These displacement tests were made to evaluate the behavior when the ratio of fluid viscosities between the displacing and displaced phases was varied. A further consequence of the test results is a comparison between displacement behavior when the displaced and displacing phases are miscible as with sugar solutions and when they are immiscible as with oil and water. INTRODUCTION Buckley and Leverett1 have presented a theory for the displacement of oil by gas or water based upon the relative permeability concept. This theory presents the displacement of oil as occurring in two phases, an initial or primary phase preceding the breakthrough of the displacing phase and a subordinate or secondary phase during which both oil and the displacing phase flow simultaneously through the same porous section. These authors gave the results of calculations to show that the percentage of oil displaced during the primary phase by water drive would be dependent upon the ratio of the viscosity of the oil to that of the water. No experimental evidence was reported by these authors to substantiate their theory. Qualitatively, however, it has been found to be in agreement with many observed field results. Laboratory investigators have been in general agreement in reporting for air or gas drive2,3 a small primary phase of production and a large secondary phase. Reported investigations on water drive3,4,5 have shown instances where both primary

Jan 1, 1950

By D. T. MacRoberts

Tins paper embodies the results of theoretical studies concerning gas reservoirs, especially the effect of drilling programs of various intensities upon pressure depletion and ultimate recoveries. The primary objective has been to determine the net quantity of recoverable gas that could be obtained as a result of each additional well, in comparison with the gas that might be secured from a single well ideally placed with respect to both acreage and geological structure. No method is yet known whereby the relative merits of intensive and sparse drilling can be compared experimentally; a reservoir must either be drilled closely or developed with wide spacing, but both programs cannot be conducted simultane-ously. Hence, the analytical method seems to be the only approach to the problem. While the present state of our theoretical knowledge does not offer a precise solution to the problem of gas flow in sand bodies, it takes such appropriate cognizance of the limitations of the methods used as to restrict any answer obtained to the realm of engineering accuracy. In solving the problem for the average gas field, it was found that practically the same answers resulted as to pressure distribution, regardless of the size of the drainage radius, even though the latter was assumed to vary from a few feet as a minimum to that of the entire reservoir as a maximum. Such limits represent extreme possibilities; therefore, the practical conditions that are associated with normal development programs, in which wells are placed in the center of tracts varying in size from 40 to 640 acres, will of necessity result in less extreme variations than those indicated in the tables accompanying this paper. Stated more concisely, the amount of gas unrecovered at abandonment (of the particular field used for illustrative purposes) will lie somewhere between 4.6 and 6 per cent of the total original content, no matter how intensively the field is drilled.

Jan 1, 1938

By AIME AIME

WHEN H. I. Smith joined the Institute back in 1908, he was an instructor in mining and metallurgy at Penn State the college from which he had graduated the year before with a B.S. degree. He had not gone far afield for his education, for he was born, February 15, 1984 at Finleyville, Pa., a small village some fourteen miles south of Pittsburgh and without doubt famous chiefly as H. I.'s birthplace. The summer that he graduated he took a trip to the copper mines Arizona and Mexico and en route worked for four weeks for the Portland Gold Mining Co. at Cripple Creek, Colo., as a mucker and trammer. The next summer he roamed farther afield mines and metallurgical works in Europe. Wishing to see more of Arizona, he left the Penn State faculty early in 1909 and went out to Wenden in that State to become mining engineer and assistant superintendent of something called the Corona Copper Co., with 72 mining claims and a one-mule-powered whim for a hoist. When that job folded he helped build the Santa Fe railroad from Parker. Ariza., to Danby Cialif., and then came back to Pennsylvania to enter Government services as a junior mining engineer with the Bureau of Mines.

Jan 1, 1943

By W. A. Lang, K. C. Gilbart, E. Stansfield

It has long been known that coal is unstable and oxidizes in air, even at ordinary atmospheric temperatures; also, that such oxidation affects the analysis of coal. Nevertheless little or no precaution is taken to prevent oxidation in the ordinary methods of analysis, and the possibility of error due to oxidation is sometimes ignored even in researches on coal. Although the general nature of coal oxidation is well known, and many workers have made careful studies of the rate of oxidation of different types of coal exposed to oxygen at different temperatures, yet the amount of oxidation coals undergo in the ordinary process of analysis, and its influence on the determined analysis, is not well known, and the published data are widely scattered through the literature. This paper is a collection, from this laboratory, of data that bear on the subject, together with a brief summary of three methods employed here to evaluate the oxidizabil-ity of coal. The post-Carboniferous coals of Alberta range all the way from anthracite down to lignite. As some of them are notably susceptible to oxidation, the necessity for care was early forced upon our attention, and oxidation has been reduced either by the removal of air with a vacuum pump or by the displacement of air with natural gas (methane). The two routine analytical operations most liable to involve oxidation are the preliminary, partial drying of the crushed coal (called air-drying) and the determination of moisture. The first is a prolonged operation on coarse coal at ordinary temperatures, and the second a short treatment on powdered coal at higher temperatures. Oxidation also occurs in coal samples stored in ordinary sample bottles. In order to gain information for this study, determinations were recently carried out on the same samples in air, in natural gas, and in vacuo. Sixteen coals were tested; three would be classed in the United States as coking bituminous coals, two as noncoking, nonslacking, bituminous coals, and the rest as subbituminous. Table 1 gives typical analyses of these coals as mined.

Jan 1, 1934

By H. M. Chance

The present value of most coal properties resides largely in the cod remaining to be mined, which thus constitutes the most important asset. The object of this paper is to discuss methods commonly used in computing the value of minable coal. To distinguish clearly between such coal values and the values of other property, the several kinds of property values should be divided into classes; so as to avoid the unintentional omission of items of importance. Value op Coal Reserves Judicial decisions prescribe, and appraisers commonly accept, current sales value as the preferred means for determining the value of transferable property. With few exceptions a property is worth the sum that can be realized from its sale by a willing seller to a willing buyer, a sale in which compulsion urges neither party, and between whom there is no community of interest to fix a value; or it is worth at least as much as a responsible buyer will offer for it. Actual sales of like property or bids from responsible buyers for the property, or for substantially like property, are the best established methods for determining values. Only in the absence of such sales or bids can valuations by other methods be entertained, and only for reasons of weight can sales values be set aside. Valuation Based on Royalties Sales of coal in the ground, as customarily carried out through lease under royalty agreements, are therefore the most trustworthy means available for determining the value of coal reserves. The constantly rising value of high-grade coal in the United States can most readily be shown by the increasing royalties per ton that can be obtained for such coals under leasehold. The rising value of land containing such coal can also, of course, be proven by the price at which such properties are actually sold as compared with prices obtainable for lands containing coal of the same grade in the past. It is exceedingly difficult, however, to establish values by the prices paid for coal

Jan 1, 1927

By S. D. Baumer, P. M. Hulme

B. M. Larsen (U. S. Steel Co., Kearny, N. J.)—Could we have some sort of an estimate on the cost of calcium carbide for this treatment? Also, if you used calcium carbide on carbon-saturated iron, would some effect hold back the reaction? P. M. Hulme (authors' reply)—As far as I know we have not worked on carbon-saturated iron. About 3½ pct C is the highest we have worked on. As far as cost goes, it depends on how much sulphur You have to take out. It will run anywhere from $0.75 to $2.00 a ton overall cost including the cost of carbide per ton of metal treated. That is, using the efficiencies that we show in this paper. We are getting better efficiencies now. T. L. Joseph (University of Minnesota, Minneapolis, Minn.)—Did you say 2 lb of calcium compound? Mr. Hulme—That is based on 10 lb of calcium carbide per lb of sulphur removed. D. E. Babcock (Republic Steel Corp., Youngstown, Ohio)—We have run this type of desulphurization process at the blast furnace. We have desulphurized between 100 and 200 at the blast furnace and taken the iron right out of the furnace with an injector system. The process gave us quite varied results; stratified iron, high sulphur on the top and low sulphur on the bottom, and we decided it was impractical. Mr. Hulme Just what was the type of injection equipment? Dr. Babcock—Nitrogen gas for one injection method and we used fairly large gun equipment. We followed the same general type of pattern you show only on a larger scale. Mr. Hulme—It sounds very much like what we call the gale of wind method. We have very erratic results with that. Dr. Babcock—We have tried several types, and particle sizes. The operation was not satisfactory. Mr. Hulme—Of course, we have never tried it on that scale except on a continuous basis. That is the reason we abandoned the idea of working on 35 ton ladles on a batch principle and took it as it came out of the cupola and treated it on the fly on a continuous basis. Dr. Babcock—When you compare the relative effectiveness of the process as carried out, it does not give a very favorable comparison of that process which is already developed. We did not feel it was worth the

Jan 1, 1952

By H. B. Aaron

DIFFRACTION micrography provides a useful tool for studying complex strain fields. Newkirk1 observed an X-ray diffraction effect due to strain interactions at the intersection of slip lines in LiF and attributed this effect to a reduction of primary extinction due to strain-gradients. It is the object of the current study to correlate the observations and rationalize the appearance of the strain fields around intersecting slip planes in x-ray extinction contrast studies by a semiempirical method. Fig. 1 shows typical strain patterns observed by Newkirk on (200) reflections in LiF using chromium radiation and a variation of the Berg-Barrett (B-B) technique. In other reflections (e.g., {220}) the strain patterns are absent. If one defines a vector 3 along the striations from the more to the less dense portion, and a vector v in the direction of the X-ray beam parallel to the reflecting plane, such that both 3 and v lie in the reflecting plane of the crystal, Fig. 1, then the positions of the striations on (200) reflections appear to be confined such that where is the angle between v and 3, Fig. 1. It will be seen later that 3 is the projection of Sb on the reflecting planes. In some instances the strain effects are observed only above the slip plane, Fig. l(C), in others only below, Fig. l(D). Where the strains appear to be both above and below the slip line, Fig. l(E), one sees that there are actually two slip lines present, Fig. 1(F) and (G). Furthermore, the strain patterns are observed in the vicinity of the intersection of emergent edge dislocations (diagonal lines on the micrograph) with emergent screw dislocations (horizontal lines on the micrograph), e.g., Fig. l(HJ) and (MN), but not in the vicinity of the intersection of two emergent edge dislocation arrays, Fig. l(HJ) and (KL). However, in the latter case the contrast of the dislocation array itself is reduced along (KL) and increased along (HJ). Line (AB) in Fig. 1 is the edge of the crystal, and the material to the left of (AB) is the side of the sample. Any empirical correlation will have to include most, if not all of the aforementioned observations. Lang2 and Newkirk1 determined that the condition for contrast is given by g-b#0 [2] where b is the Burgers' vector and g the diffraction vector (normal to the reflecting planes). If one assumes that the direction of the observed strain fields is given by the vector sum of the slip vectors (Sb1) of the intersecting slip planes, then Eq. [2] may be generalized to g-S#0 [3]

Jan 1, 1963

F. WEIMER,* Washington, D. C. (written discussiont).-For electrical measuring instruments, especially those types that involve the Wheat-stone bridge or potentiometer principle and standards of electrical resist-ance, there has been, for a considerable time, a need for better resistance materials. For a satisfactory resistance material, much depends on the purposes for which it is to be used. For potentiometers and Wheatstone bridges, such as are in more or less general use, and the more common forms of resistance standards, a good quality of manganin answers fairly well. However, it should not be presumed that manganin is considered ideal for the purpose, for in measuring instruments and resistance stand-ards, there is still much to be desired. An experience of more than 10 years in the study of the resistance standards and resistance apparatus shows that manganin resistances change with time in a way that is very annoying and the maintenance of the unit of resistance to the desired accuracy requires an excessive amount of work or may be said to be prac-tically impossible. The changes in resistance are generally most rapid and erratic in resistances of very low and very high values. In resist-ances of low value, the resistance material is often in the form of thin sheets so that the surface is large and usually more or less unprotected from the atmosphere, or the oil in. the case of oil-immersed standards. In resistances of high value, the resistance material is in the form of fine wire and, therefore, the surface is large compared with the cross-section. In resistances of medium value, the surface is less, compared with the cross-section, or better protected, usually by a silk wrapping impregnated with shellac. This suggests that one of the difficulties with manganin is slow surface action or oxidation, even when an effort has been made to protect the surface from such action However, the changes observed cannot all be accounted for on this basis. There are, presumably, also some internal changes in the resistance material even when it has been annealed. Further; the changes in manganin resistances seem to be more or less independent of its electrical properties. In other respects, too, manganin is not ideal.

Jan 11, 1919

Jan 1, 1914

Jan 1, 1956

Jan 1, 1946

Jan 1, 1941

By T. F. Witherbee

THE following calculation of heat requirement covers the working of the furnace from January 25th to February 14th, inclusive. A short time previous to the first date the furnace had been working rather badly, so that 300 lbs. of ore and 500 lbs. of limestone were taken off. Within the time mentioned the quality of the iron passed

Jan 1, 1877

Jan 1, 1945

By A. S. McCreath

Jan 1, 1884

Jan 1, 1941

By R. H. Terhune

THE enormous production of pig-iron, together with the many difficult and interesting problems with which its manufacture is fraught, has secured to this industry the exclusive attention of scientists with reference to the chemistry of iron, while some of the minor departments of its metallurgy have suffered neglect. Particularly is

Jan 1, 1873