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By H. H. Stoek

The fundamental reasons underlying the choicc of a method of mining a coal seam are safety of operation, cheapness of producing the coal and the character of the product as a saleable article. From the standpoint of safety, open or strip coal mining is always preferable, as many of the dangers inherent to underground work are absent, such as explosions of gas and dust, falls of roof and coal, and also to a great extent those due to haulage and the use of explosives, thus eliminating three of the chief causes of accident from which about 75 per cent. of the underground accidents in coal mines occur. The conditions under which coal is stripped also make the work much safer than ordinary quarry work, as the depth of the pit is usually comparatively small. Prom the standpoint of low mining cost, there is much misapprehension and many of the costs given are misleading in that they do not take into account such items as the destruction of the surface for future use, the full cost of the removal of the overburden, depreciation, amortization, coal depletion, loss of time through floods and from bad weather in winter, etc. Coal is no doubt often put on the cars at less cost by stripping than by underground mining, but by no means always so, as is too generally assumed. In some cases coal must be obtained by stripping or not at all, because the small amount of overburden renders underground mining impossible.

Jan 1, 1918

By M. C. Fuerstenau, R. B. Bhappu

The response of beryl to sulfonate flotation was examined. The dependence of flotation recovery on sulfonate concentration, pH, and the absence or presence of various ions is also demonstrated. The response of quartz and feldspar to sulfonate flotation at various values of pH is given to. show the conditions necessary for selective separation. Finally, beryl was successfully concentrated from a natural ore using a technique devised from experimental observations on systems of pure minerals. With the possible exception of quartz, the flotation characteristics of silicate minerals are rather poorly understood. This is due in part to the com- plexity of the mineral systems themselves and in part to an insufficient amount of flotation data. The complexity of the systems arises from the wide range of chemical composition that the silicate minerals can assume. This is reflected in the variability of such physical properties as hardness and cleavage. Although the chemical composition of silicate minerals can vary considerably, a general grouping can be accomplished conveniently on the basis of the assemblage of SiO4 tetrahedra in all the silicates. That is, it has been shown that six basic groups can be obtained, depending on the arrangement of oxygen sharing between adjacent silicon atoms (or substituted aluminum). When all four oxygen atoms are shared, a framework structure such as quartz or feldspar is obtained. When three oxygens are shared, infinite sheets are obtained as in the micas and clays. When two oxygen atoms of the tetrahedra are shared, infinite chains are obtained, such as those in

Jan 1, 1963

CONTENTS PAGE BAIN, EDGAR C.-The Nature of Martensite. Discussed by Ancel St. John, Henry S. Rawdon, Jerome Alexander, Howard Scott 1 FEILD, ALEXANDER L.-Effect of Zirconium on Hot-rolling Properties of High-sulfur Steels and the Occurrence of Zirconium Sulfide. Discussed by Beram D. Saklatwalla, Bradley. Stoughton, Andrew M'Cance, George F. Comstock, Alexander L. Feild 12 SAUVEUR, ALBERT and KRIVOBOK, V. N.-Use of Sodium Picrate in Revealing Dendritic Segregation in Iron Alloys. Discussed by George F. Comstock, John H. Hall 17 KINNEY, C. L., JR.-Economic Significance of Metalloids in Basic Pig Iron in Basil Open-hearth Practice. Discussed by V. J. Pazzetti, George B. Waterhouse, C. L. Kinney, Jr 19 NEAD, J. H.-Absorption of Sulfur from Producer Gas in Open-hearth Furnaces.. Discussed by George B. Waterhouse, C. L. Kinney, Jr 26 PRIESTLY, WILLIAM J.-Effect on Steel of Variations in Rate of Cooling in Ingot Molds. Discussed by Emil Gathmann, Paul E. McKinney, George A. Dornin. 27 MONYPENNY, JOHN H. G.-Stainless Steel, with Particular Reference to the Milder Varieties (Stainless Iron). Discussed by P. A. E.-Armstrong, Beram D. Saklatwalla 33 ROYSTER, P. H., and JOSEPH, T. L.-Effect of Coke Combustibility on Stock Descent in Blast Furnaces. Discussed by Ralph H. Sweetser,. Richard Franchot, Sidney Cornell, T. L. Joseph 41 DAVIS, F. W., and BOLE, G. A.-Observations on Requirements of Refractories for Open Hearth. Discussed by C. L. Kinney, Jr., L. F. Reinartz, P. E. McKinney 46

Jan 5, 1924

By H. H. Stoek

THE fundamental reasons underlying the choice of a method of mining a coal seam are safety of operation, cheapness of producing the product and the character of the product as a saleable article. From the standpoint of safety, open or strip coal mining is always preferable, as many of the dangers inherent to underground work are absent, such as explosions of gas and dust, falls of roof and coal, and also to a great extent those due to haulage and the use of explosives, thus eliminating three of the chief causes of accident from which about 75 per cent. of the underground accidents in coal mines occur. The conditions under which coal is stripped also make the work much safer than ordinary quarry work, as the depth. of the pit is usually comparatively slight. From the standpoint of low mining cost, there is much misapprehension and many of the costs given are misleading in that they do not take into account such items as the destruction of the surface for future use, the full cost of the removal of the overburden, depreciation, amortization, coal depletion, loss of time through floods and from bad weather in winter, etc. Coal is no doubt often put on the cars at less cost by stripping than by underground mining, but by no means always so, as is too generally assumed. In some cases coal must be obtained by stripping or not at all, due to the small amount of overburden that renders underground mining impossible.

Jan 9, 1917

By Mark Malamphy

THE occurrence of outcrops of bituminous schists and sandstones impregnated with heavy asphaltic petroleum first directed attention to the Sao Pedro area as a possible source of commercial production of petroleum. Since 1920, more than 20 wells have been drilled in this area. The discovery of oil shows and small quantities of natural gas in some of the early wells led to the continuation of drilling in the hope that more important findings would result. During the early part of 1934, detailed magnetometer observations were made in this area, and a con-siderable number of torsion balance stations were occupied. The results of these geophysical observations help considerably to clarify the structure of the area and the very considerable amount of geologic information available makes possible a much more exact interpretation of geo-physical anomalies. In presenting the results of these observations, and interpretation of the geophysical data, certain actual case problems are included; i.e., geophysical anomalies due to anomalous masses of which the forms and positions are more or less known. Although anomalies due to igneous intrusions are probably more important to geophysicists in Brazil than in other countries, these data have a certain interest for all geophysicists, particularly because they were obtained in the south magnetic hemisphere, where the lines of magnetic force are directed upward, and in a region of moderately low inclination. This is considered as a geological-geophysical problem, and only passing mention will be given to the petroleum possibilities of the area.

Jan 1, 1936

By Mark Malamphy

MOST igneous rocks, and particularly those of the basic type, con-tain relatively high percentages of magnetite and other iron oxides, which give them moderately high magnetic susceptibilities and make them responsible for an important percentage of the magnetic anom-alies observed during the course of geophysical surveys by the mag-netic method. The irregular form and high susceptibility of the igneous rocks make them readily polarizable and the position and strength of the magnetic poles formed are not always explicable by theoretical calculations of anomalies due to certain assumed forms in the normal magnetic field of the area under study. During the last four years our field work has permitted us to make detailed observations of anomalies due to igneous rocks in all the states of south Brazil. The form and position of the igneous rock at some places were fairly accurately known, which made it possible to calculate theoretical anomalies and compare them with the observed data. Some of the data we obtained have been published and additional cases are now awaiting publication. In this paper, we will present a few specific cases where the geology is moderately well known and which we believe to be of considerable value as representing typical magnetic anomalies in the south magnetic hemisphere, where the inclination of the magnetic field is very low. Although the vertical intensity is negative in the Southern Hemis-phere, we have adopted the convention of plotting increase in intensity (negative) as a positive anomaly; i.e., above the x axis. This conven-tion facilitates comparison with anomalies in the north.

Jan 1, 1936

By A. Hultgren

PAGE Outline of Progress of Knowledge and Theories about Gas Evolution in Steel Ingots, and Its Influence on Crystallization and Segregation 2 Object of Present Investigation 16 theoretical Discussion of Process of Solidification 17 Gas Given Off from Rimming Steel during Solidification 17 Equilibrium Diagram of the Iron-carbon-oxygen Alloys 19 Solidification of Pure Iron-carbon-oxygen Alloys 25 Solidification When Carbon Monoxide Is Given Off at Constant Pressure... 25 Solidification When Gas Evolution Is Suppressed 26 Schematic Application on Solidification of Rimming-steel Ingots 27 Influence of Manganese, Sulphur and Phosphorus 28 Experimental Work 30 Liquid Steel and the Mold Gas 30 Ingots Investigated and Methods Used 33 Ingot Structure 42 Structure of Rim Zone 42 Structure of Core 49 Structures Obtained under Special Conditions of Freezing 50 Distribution of Metalloids 55 Other Observations Made 60 General Discussion of Solidification Process 63 Condition of Liquid Steel before Casting 63 Rimming Period 70 Composition of Rim Zone 93 Freezing after Top Is Closed 96 Slag Inclusions and Ingot Scum 102 Reaction between Gas in Blowholes and Surrounding Solid Steel during Cooling 103 Summary 105 Appendix-Preparation and Etching of Ingot Sections 106 References 107 IN 1934, Jernkontoret (The Swedish Ironmasters' Association) appointed a committee for the study of the structure of rimming-steel ingots and the various phenomena associated with their solidification. The members of the committee, including those who have joined it later, have been: I. Bohm, B. D. Enlund, B. Kalling, M. Tigerschiöld, 1. Wohlfahrt and the authors. The present paper? is a somewhat

Jan 1, 1939

By AIME AIME

EVER since Henry Bessemer, nearly 100 years ago, developed the steelmaking process that bears his name, occasional variation has been noted in the quality of steel made in the acid converter, owing largely to the difficulty of stopping the ? refining-which takes only ten to twelve minutes -at precisely the right moment. Principally as the result of this, the amount of Bessemer steel made in the United States gradually declined over the years until it is now about 7 per cent of the total.

Jan 1, 1943

By AIME AIME

THE name of Dr. Henry Sturgis Drinker has been added to the short list of Honorary Members of the American Institute of Mining and Metallurgical Engineers, a signal honor rightfully bestowed. To quote the Philadelphia Inquirer, "It is essentially a recognition of the highest achievements, the greatest benefits, and most deserving personalities among engineers themselves." The regard in which Doctor Drinker is held by his friends and associates is reflected in the following comments of the press: Doctor Drinker is distinguished far beyond the confines of Bethlehem and of Lehigh University, to the development of

Jan 1, 1921

By Clyde Evarts Weed

SOME one once affirmed his great belief in luck, adding that he had found that the harder he worked the more luck he had. Clyde Weed is a firm believer in this method of courting the fugitive lady. He is at work early and late, often leaving his staff at Anaconda's offices at 25 Broadway breathless trying to keep up with the ideas teeming from a fertile brain and the actions those ideas entail. Miles ahead of his assistants much of the time, he still manages to be an agreeable fellow to work with, no small accomplishment as many can testify. Mr. Weed arrived in the world at Moorestown, Mich., on Aug. 8, 1890. Sixteen years later he entered Michigan Agricultural College, a lowly freshman. The following year, with the experience and wisdom expected of a sophomore, he transferred his studies from the reaping of a harvest on the surface of the earth to delving into the deeper, unpredictable bowels of the earth, his studies now shifted to the Michigan College of Mines. Last June his alma mater conferred upon him the degree of Doctor of Engineering.

Jan 1, 1947

By AIME

IRWIN W. ALCORN, present Chairman of the Petroleum Division, was born Sept. 5, 1899 at Marietta, Ohio, and moved with his family to Robinson, Ill., at the time of the early oil development there. This was in the days of the Star spudders, mud, mules, and Stanley steamers. Al graduated from Robinson High School after participation in basket ball, also attaining the captaincy of the football team of that school. He entered Missouri School of Mines and Metallurgy in 1918 and was ushered by the Army into the S.A.T.C. In 1920 he transferred to the Massachusetts Institute of Technology, later to return to receive his B.S. degree -in metallurgy at Rolla, also joining the AIME. On graduation, he worked for the Skelly Oil Co. at Cushing, Okla., shifting to the Moore Refining Co. at DeNoya, Okla., as superintendent of a small pipe-line system. After an interval of two years with the National Supply Co. in Tulsa, he joined the Independent Oil and Gas Co. of that city, and at various times was chief engineer of the Texas division, superintendent of the West Texas pipe-line system, chief engineer of pipe-line construction, and chief engineer of the refining division. Al organized the Company's production engineering department. In 1930 the Company was merged with the Phillips Petroleum Co. The depression was in and Al was out, 'as was true nine months later when the Smith Separator Co. whose chief engineer he had become, was liquidated. The next few years was spent with Oil Well Supply Co. as a subsurface pumping equipment engineer

Jan 1, 1948

Jan 1, 1923

Jan 1, 1923

By LOWELL LAWRENCE

MAGNETITE minim and milling in the Eastern States continued at a low rate of production during 1934. The year's output was 50 per cent greater than in 1933, but when one considers that the 1934 output was only 1.5 per cent of the combined plant capacities of the eastern iron ore producers, the far-reaching effect of unrestricted importation of foreign ores and pig iron is apparent. The Chateaugay Ore and Iron Co., at Lyon Mountain, N. Y., produced 1.00,136 gross tons of concentrated and sintered ore up to Nov.1, when operations were closed clown. At Mineville, the Witherbee, Sherman Corp. confined its productivity to part-time operation of its Old Bed and Harmony mines front May 1 Lo Oct. 27. This period of activity was brought about by the use of Mineville ores in the recent blast made by the Green Island furnace at Troy, N. Y. The Forest of Dean property at Fort Montgomery, N, Y., has continued closed down during the year.

Jan 1, 1935

Executive ARTHUR S DWIGHT, Chairman B THAYER CHARLES F RAND P MATHEWSON J V W REYNDERS Membership WILLIAM H BASSETT, Chairman W Y WESTERVELT Vice-chairman P MATHEWSON H G MOULTON F T RUBIDGE Finance WALTER H ALDRIDGE, Chairman GEORGE D BARRON GALEN H CLEVENGER

Jan 1, 1923

By Lynn C. Jacobsen

Among the unforeseen consequences of the 1973 Arab oil embargo has been a considerable array of new or increased taxes on the so-called energy minerals. These taxes will be the subject of this report. Both Federal and State taxes have been enacted, but I will be concerned mostly with state severance taxes and particularly those on uranium. Severance taxes are considered to include all taxes having the distinctive feature of being applied on a natural resource at the stage of extraction. The tax may be based on units of production or on value, and if on values it may be on gross value or on gross value less either arbitrary or cost-related deductions. The tax has a number of aliases - resource excise tax, conservation tax, privilege tax, mining excise tax, ad valorem production tax, and more - and this makes comparison of tax burdens among states difficult. The windfall profit tax on oil is an example of a severance tax at the Federal level. Severance taxes are an established feature of state tax systems, but they continue to be a controversial issue, and proposals to raise or modify existing severance taxes are regularly submitted to the legislatures of the Western energy producing states. No concensus exists as to what is a reason- able and proper level of severance taxation or to the form it should take. The taxes which have been adopted by the various states reflect the interaction of a variety of interests and the specific circum- stances in each state. What follows is a summary of theoretical, practical, and emotional viewpoints and arguments that surface in any statehouse in which a severance tax bill has been introduced. The New Mexico experience will be heavily relied upon. THE ECONOMISTS Marginal effects. A severance tax which is based on a gross percentage of revenue or on units of production is a constant addition to variable costs, and to the mine operator has the same effect as any other increase in operating costs. The direction of these effects is straightforward: the tax will cause the property to have a lowered present value, to be mined at a lower rate than without the tax, raise the minimum grade that will be mined, lead to lower total recovery, make marginal properties sub-marginal and discriminate in favor of richer, more profitable operations (Lockner, 1965; Steele, 1967). In the short run, production facilities are fixed and imposition of a severance tax will have little effect on production levels. In the longer term, capital is mobile and investment and exploration expenditures will shift from minerals and jurisdictions with high taxes to those with low taxes. Over a considerable range of taxation the effect will be to change the relative position of the taxing state, but an overly optimistic evaluation of the capacity of mineral producers to absorb a tax can bring an industry to a halt. It is generally acknowledged that imposition of high severance taxes on taconite in Minnesota stopped development completely, and that only the adoption of a constitutional amendment limiting the amount of taxes that could be imposed in the future brought the firms back and encouraged them to make the huge investments required (Weaton, 1969). A tax which is a percentage of the net operating income (gross revenue less cash operating costs) does not influence the cut-off grade for recovery nor change the time preference for extraction, and hence, is free of the negative features of the tax applied to gross revenues or units of production. In theory it is a more efficient tax but relative administrative complexity and inherent difficulty in predicting revenue have discouraged its use. The Wyoming severance tax on uranium, which uses grade of ore as well as price in establishing taxable value, is the most cost related, and hence, the most neutral and efficient of the various state severance taxes on uranium. Economic rent. Despite the discrimination and the anti-conservation aspect inherent in most severance taxes, economists generally endorse their use because they are seen as a vehicle to appropriate rents - that is, returns greater than the long-run competitive supply price. Conspicuous examples of supposed economic rents are the returns to oil producers because of the OPEC cartel, the returns of the uranium producers under AEC buying contracts in the 19501s, and the high prices obtained by the uranium producers for contracts entered into in the 1976-1979 period. Mining of coal in the Western states is believed by some to generate huge economic rents because of the OPEC caused increase in price of a competitive fuel (McLure, 1978, p. 261), and possibly because of clean air regulations favoring the burning of low-sulfur coal. In theory, such surplus returns could be taxed completely away without affecting supply. In practice, the situation is more complex (Steele, 1967, pp. 234-236); economic rent of mineral production is an elusive quantity involving as it does replacement costs, and technical and market risk, and it, like beauty or pornography, probably exists mostly in the eye of the beholder. Rent may also be perceived to be present in the upper portion of a cyclic market which also has a downside. Where rent exists, it is almost certain to be short-lived - cartels self- destruct, government subsidies end, competitive adjustments occur - but the taxes imposed to capture it tend to be immortal. There is little doubt that the perception of un- usual and undeserved (obscene) profits in the mid- and late 1970's was a major factor in the adoption of energy mineral taxes strikingly higher than had been previously considered. At the New Mexico legislature of 1977 supporters of a moderate tax were repeatedly confronted with some variant of the statement, "You can't expect me to believe that a

Jan 1, 1982

By W. A. Backofen, D. L. Holt

Push-pull fatigue tests have been carried out at 4.2°K, 77oK, and room temperature on two poly crystalline materials of widely different stacking-fault energy (?): pure copper (? - 70 ergs per sq cm) and the Cu-8 wt pct A1 alloy (? - 2.8 ergs per sq cm). Constant stress-amplilude was imposed and measurement was made of the plastic-strain amplitude (ep) at saturation. Lives extended from 104 to 106 cycles. Designating lives at the various temperatures by NRT, N77, and N4.2. the ratios N77/NNT and N4.2/N77 ranged from 3.5 to 18 under the condition of common Ep . Metallo-graphic examination revealed different crack morphology in Cu-8 Al fatigued at room temperature, and at 77" and 4.2oK. At room temperature, cracks lay in or near grain and lain boundavies; at 77o and 4.2oK. cvacks were transcrystalline. Tests on single crystals of Cu-8 A1 showed that such a change in the cracking mode in polycrystallitle material accounted for a factor of- about 3.25 in N77/NRT . The longer life at lower tewperatztre (conslant cp) has heels attributed to two deuelopinents: a reduced production of the dislocation tangles and subgrain boundaries which serve as paths of rapid cracking, and suppression of oxygen chetni-sorption at the crack tip It was concluded that in both materials the luller accounted for an extension of the life at 4.2oK beyond that at room temperature by a factor of 15. XV ECENT experiments on the fatigue of Cu-A1 alloys in the so-called high-cycle range (greater than lo4 cycles) have emphasized the importance of stacking-fault energy (y) as a quantity affecting crack propagation rate and fatigue life.1,2 It was found in comparisons at essentially fixed plastic-strain amplitude that crack growth rate decreased by a factor of about 5 over the composition range from copper (? - 70 ergs per sq cm) to Cu-8 wt pct Al (? - 2.8 ergs per sq cm). The argument was made that, when stacking-fault energy is high, cross slip and climb are favored, so that dislocation tangles and/or subgrain boundaries form more readily under cyclic loading. Since the boundaries and tangles act as paths of rapid crack propagation ,3, 4 life is shortened as a result. However, when stacking-fault energy is reduced (as by alloying), cross slip and climb become more difficult, with the result that substructure formation is retarded and growth rate is also reduced. A purpose of the present work was to investigate the substructure effect in relation to temperature. As temperature is lowered, ? is varied only slightly (if at all), but decreased thermal activation can interfere with cross slip and climb. Thus substructure formation could be curtailed and life increased. Fatigue life in the high-cycle range is also known to be strongly influenced by environment. Working with copper, Wadsworth and Hutchings observed that life in a vacuum of 10-8 mm Hg exceeded life in air by a factor of 20.5 They isolated oxygen as the agent that furthered cracking. While the details are still unclear, a requirement in any mechanism of oxygen-accelerated cracking is that there be chemisorption at the crack tip. That could prevent welding on the compression half cycle,= interfere with reversal of slip,1, 6 or aid in breaking metal-metal bonds at the crack tip.5'7 In the work being reported here, temperature was lowered by immersion in liquid nitrogen and helium, which also served to reduce both the oxygen concentration and chemisorption rate. A possible effect upon life, i.e., a lengthening, had to be recognized. Several researchers have determined fatigue lives at low temperatures presenting their results in the form of stress amplitude (S) vs cycles in life (N) curves.8-11 Such curves reflect, primarily, the fact that metal is strengthened by lowering temperature; effects of substructure and changing environment tend to be masked. The difficulty can be overcome by comparisons based on identical plastic-strain amplitudes, and in the present work the dependence of life on both plastic strain and stress amplitude was established. EXPERIMENTAL Materials. The principal materials were polycrystal-line copper (? - 70 ergs per sq cm)" and the Cu-8 wt pct Al alloy (? - 2.8 ergs per sq cm),I3 the latter being near the limit of solubility of aluminum in copper and having, therefore, the lowest stacking-fault energy in the CU-Al system. Specimens were machined from 0.118-in.-diam cold-swaged rods of high-purity (99.999 pct) copper and the Cu-8 Al alloy, the latter produced initially in a graphite boat by induction vacuum melting a mixture of 99.999 pct Cu and 99.99 pct Al. The machined specimens were annealed to produce mean grain diameters of about 0.070 mm in copper and 0.190 mm in the alloy. Specimen dimensions are given in Fig. 1. Values of the tensile yield stress, ultimate strength, uniform strain (determined by the Considgre construction), and reduction of area, for both materials at 4.2oK, 77oK, and room temperature, are listed in Table I. The tensile apparatus in which these results were obtained has already been described.14 Apparatus. Specimens were fatigued in push-pull with a machine that is illustrated schematically in Fig. 2. The specimen is first soldered into the top grip (1) with Woods metal, and the grip is then screwed into the inner tube (2) which is connected to the drive rod of the Goodmans vibration genera-

Jan 1, 1968

Jan 1, 1967

Jan 1, 1967

N/A

Jan 1, 1945