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By A. D. Zunkel, A. H. Larson

Equilibrium antimony contents of pb-sb alloys in contact with PbO-Sb2O3 slags containing less than 45 mole pct Sb203 uleve determined at 650', 700°, and 750°C in an inert atmosphere. In this ten~pevature range, the antimony contmzt of the alloy increased with increasing temperature at all slag compositions. The PbO-Sb203 phase diagram below 28 mole pct Sb2O3 was determined by thermal analysis and by application of a log sbZ4/y$b0 us plot determined from the equilibrium-activity data. The resulting phase diagram showed a eutectic at a temperature of 604°C and a comfiosition of 21.6 mole pct Sb2O, with a maximum terminal solid solubility of Sb203 in PbO of 5.6 mole pct. These results are compared with existing data in the literature. In the past three decades, only a small amount of experimental work has been done on the slag-metal equilibria in the Pb-PbO-SbaO3 or the analogous arsenic and tin systems. These systems are important in commercial lead-refining processes such as softening and dross fuming since it is impurities such as antimony, arsenic, and tin in lead bullion and Sb2O3, As2O3, and SnOz in lead drosses which must be re-

Jan 1, 1968

By H. E. Cline

Calculations of the formation and growth of faults caused by a variation in lumellar widths were made for a two-dimensioml three-plate problem. The angle between the a-ß boundary and the growth direction was allowed to vary and the time evolution was studied using a quasisteady state approach. At spacings smaller than a critical spacing given by X V = AO variations in the larrlellar widths grow in time to produce faults that coarsen the structure, while at spac-ings larger than this critical spacing, variations in the lamellar widths decay in time. If small plates are introduced into the structure they may grow only at large spacings to refine the structure. The time evolution and shape of faults were calculated for the three plate-problem and then the three dimensional problem and rod-like eutectic were qualitatively discussed. UNDERSTANDING of the mechanism by which the spacing of directionally solidified eutectics is determined may allow one to control their structure better. Steady state solutions for the growth of lamellar structures have been found for a range of lamellar spacings A and growth velocities V. To obtain a unique solution for the isothermal growth of pearlite, Zener1 assumed that growth occurs at a maximum velocity, while Tiller2 assumed that a eutectic alloy, grown under an imposed velocity, will choose a spacing corresponding to minimum undercooling. These assumptions are equivalent and have been referred to as "extremum growth". The extremum condition predicts the observed relation between velocity and spacing as given by V = constant [I] but does not provide a mechanism for changing the lamellar spacing. Jackson and Hunt3 calculated the interface shape by using solutions to the diffusion equation for a planar interface and a relation of the interface composition to the local curvature. If the spacing is much larger than the extremum spacing, the interface breaks down catastrophically to form forked plates. However, the catastrophic breakdown cannot account for the small adjustments in spacing that must occur in practice..3 Direct observations during the growth of organic eutectics4 and the Pb-Sn eutectic5 show that spacing changes occur by the formation of faults. A fault in a plate-like eutectic is the edge of a plate. Once the faults form, they may move to make small adjustments in the spacing.6,3 The motion of faults intersecting the growing interface was shown by an approximate analysis to give Eq. [I].6 A perfectly regular lamellar structure should be able to persist over a range of lamellar spacings. However, during growth small perturbations in the structure may occur. If the amplitude of the perturbation increases in time the structure is unstable, while if all possible perturbations decrease in time the structure is stable. In a previous paper7 variations in the shape of the solid-liquid interface were considered, while this paper considers only variations in lamellar widths while maintaining a macroscopically planar solid-liquid interface. Previously, theories of lamellar growth1"3 have artificially contrained the growth to give a regular periodic structure. To allow for a variation in spacing, the three phase intersections and groove angles were allowed to change with time as determined by assuming local equilibrium. THREE-PLATE PROBLEM Since the spacing changes in eutectics by local formation of faults,4'5 it is suggested that local variations in spacing are responsible. The interaction between neighboring plates will be greatest because they have the smallest diffusion distance. For simplicity, as a nearest neighbor approximation, a three-plate problem will be considered, as illustrated in Fig. 1. The structure consists of a periodic array in which all the plates are allowed to vary in width. As in steady state growth it is assumed that the average composition in the solid remains constant. A variation in plate widths, that maintains the composition in the solid, was introduced by making the first a-phase plate thinner by an amount A, keeping the width of the second B-phase plate constant, and increasing the width of the third a-phase plate. If the structure were not perturbed, as in the regular two-plate problem previously described,' then the groove angles at the three-phase junctions are the equilibrium angles, 0, and ? B, and the solid-solid boundary is normal to the interface. In the three-plate problem with a variation in plate widths the phase boundaries are assumed to be related to the three-phase junction by equilibrium angles, but the a/B boundaries may be rotated by an angle 0 from the growth direction. The angle H be-tween the tangent to the a/B boundary and the growth direction may vary during growth and determine the —> — — —.A_ Q-0 / 0 x, X2 Fig. 1—Schematic of the three-plate problem showing a variation in the spacing and the effect on the angles at the three phase intersections.

Jan 1, 1970

By D. G. Westlake

Levine has concluded that prismatic slip in titanium is controlled by two distinct thermally activated processes in the temperature ranges O° to 220°K and 220" to 300°K. We feel that his evidence is not convincing. He has drawn a curve through the plot of activation volume u* vs temperature T with a break at 22WK, Fig. 2. We believe that considering the possible experimental error apd the fact that there are only four points between 4° and 196°K, one could be justified to represent these points by the smooth curve we show as a solid line in Fig. 12. Levine believes that (8rf/aT)+ is discontinuous at 220°K, but he hints that he recognizes the possible doubt. We doubt seriously that the results shown in Fig. 1 indicate a discontinuity at 220°K. Certainly if he were justified in drawing a straight line through only four points on Fig. 2, we are even more justified in drawing straight lines through the seven points between 77" and 297°K on Figs. 1 and 3, because a straight line touches all seven of his circles. If his measurements of t were so precise that his decision to draw two curves in Fig. 3 is valid, then the experimental technique is deserving of further mention. We have drawn a smooth curve through the results in Fig. 3 and used this and the curve in Fig. 12 to obtain the values of shown in Fig. 13. Finding continuous is a contradiction of Fig. 4, which deserves comment itself. Levine obtained the solid circles in Fig. 4 using Fig. 2 and a smooth curve through the points shown in Fig. 3. We have replotted these solid circles in Fig. 14. We submit that there is no basis for his two straight lines (dashed in Fig. 14), and therefore have superimposed the curve that we believe is indicated. Certainly, there is reasonable doubt that a discontinuity in dH/dT exists at 220°K, even when one accepts Fig, 2. Furthermore, if one draws the straight lines indicated by least-squares treatments of the results presented as open circles in Fig. 4, their intersection is at about 196°K, not at 220°K as shown. Thus the alleged agreement between Figs. 3 and 4 with respect to "break" temperatures is not apparent. In Fig. 9, Levine has drawn a straight line very much different from the one indicated by a least-squares treatment. Obviously, he has done this because he recognized that H = 0 when T = 0. He is consistent in drawing the low-temperature curves in

Jan 1, 1968

By W. W. Weigel

In "Mine Drainage, Southeast Missouri Lead District," Trans. AIME, (1943) 153, 74-81, the general water conditions in the lead mines of Southeast Missouri were described. Some comments developed from the experience of time and some further

Jan 1, 1949

By Don L. Kendall, Martin G. Buehler

A simple physical model has been developed to fit carrier-removal data in silicon irradiated near room temperature with reactor spectrum neutrons. Commonly observed donor and acceptor defect energy levels are assumed to be introduced linearly with neutron fluence. The donor levels (in ev) are Ev + 0.16, Ev + 0.27, and Ev + 0.31 and the acceptor levels are Ec - 0.55, Ec - 0.40, and Ec - 0.1 7, where Ev and Ec are the valence and conduction band energies, respectively. The introduction rates of each level are adjusted to fit literature initial carrier-removal rate data. When normalized with respect to the Ev +0.27 level, the relative values of introduction rates are 5.3, 1.0, 3.1, 1.0, 2.0, and 20.0, respectively for the six levels indicated above. To fit p-f (hole concentration vs neutron fluence) and n-f (electron concentration us neutron fluence) data, the introduction rates are multiplied by a factor which preserves the relative values given above. This factor depends upon irradiation temperature, reactor energy spectrum, neutron fluence calibration, and oxygen content of silicon. An extensive study of the effect of neutrons on carrier-removal in silicon irradiated with reactor spectrum neutrons (E > 10 kev) has been given by Stein and Gereth1 (SG) and Curtis, Bass, and Germano' (CBG). They measured initial carrier-removal rates for both p- and n-type silicon over an impurity range typical of silicon devices. In this work, we attempt to fit a simple theory to this data to establish a usable relationship between hole and electron concentration, p and n, respectively, and neutron fluence f. The p-f and n-f relations are needed to assist in the design of neutron tolerant silicon devices and are needed to clarify presently used empirical resistivity-fluence relationships.3 Neutron damage in silicon produces a variety of defects ranging from simple point defects to defect clusters. For the purpose of this treatment, we assume that simple point defects dominate carrier-removal effects. In contrast to this view, stein4 has proposed that defect clusters are responsible for a significant portion of carrier-removal effects. In the following section, it is shown that the carrier-removal effect in n-type silicon with an electron concentration less than 1015 cm-3 can be explained adequately by assuming that the divacancy is the dominant defect and that its introduction rate is independent of the electron concentration. For electron concentrations greater than 1015 cm-= an additional acceptor defect center is needed, and for simplicity the A-center (vacancy-oxygen pair) has been chosen. Although the E-center (vacancy-phosphorus pair) can account for some of the results, the A-center was chosen because the E-center requires a more involved treatment which the presently available data do not justify. In p-type silicon three radiation-induced donor levels are assumed, namely the divacancy and two other centers of unspecified nature located at Ev + 0.16 ev and Ev to 0.31 ev. The donor divacancy at Ev + 0.27 ev is assumed to be introduced at the same rate in p-type as in n-type. However, this rate is too low to fit p-type initial carrier-removal data. The dominant centers in p-type silicon are assumed to be the Ev + 0.16 ev and Ev + 0.31 ev levels where the latter is not the divacancy. The introduction rates are chosen to fit initial carrier-removal rate data. Assuming that the introduction rates are independent of Fermi level, the ratio between them is fixed for subsequent p-f and n-f calculations. Using the same ratios, the initial carrier-removal rate data1,2 as well as p-f and n-f data1,5 can be fit provided the absolute value of the introduction rates are adjusted to account for irradiation temperature, reactor energy spectrum, neutron fluence calculation, and the oxygen content of silicon. THEORETICAL ANALYSIS This analysis is basically the same as that used by Hi116 to analyze electron damage in silicon except we express the degree to which an impurity level is ionized not in terms of the Fermi level, but in terms of carrier concentration. Landis and pearson7 have used the latter approach to analyze y-damage in silicon. Neutron-induced defects responsible for carrier-removal at room temperature are assumed to be simple point defects with no interaction between defects so that they may be represented by discrete energy levels. It is also assumed that no constituent of a defect complex is used up and defects stabilize shortly after irradiation. Defects are assumed to be introduced linearly with fluence according to the product Rtf where Rt is the defect introduction rate and f the neutron fluence. Taking into account the ionization of defects according to Fermi statistics, and considering charge neutrality where minority carriers are neglected, the n-f relation is where no is the preirradiation electron concentration. The parameter Nt is the electron concentration at which the ionized defect concentration is one-half the total defect concentration (Rtf) or where Et is the defect energy level. For silicon at 300°K, ni = 1.45 X 1010 cm-3 and Ei = Ev+ 0.542 ev which was determined using Ec — Ev = 1.11 ev and me* = 1.07 mo and mh* = 0.558m0. The spin degeneracy factor, which usually appears as a number multiplying the Nt/n term of Eq. [1], is taken as unity. In effect, this factor has been incorporated into the defect en-

Jan 1, 1970

By Douglas Bunting

The first presentation of this paper was before the Pennsylvania Anthracite Section of the Institute in May, 1914, after which a committee was selected to verify and add to the data contained in the original paper. The author is indebted to G. W. Engel, H. W. Montz, R. V. Norris, and H. H. Otto, of this committee, for additional information. I also wish to acknowledge the courtesies extended me by a number of the mining companies for information relative to accidents, systems of proving, and mining practice. The paper should bring forth additional criticism and recommendations, which will be of value in establishing future practice relative to this subject. Throughout the northern anthracite field of Pennsylvania glacial and alluvial deposits of sand, gravel, and clay exist in varying quantities. The extent and character of these deposits are described by N. H. Darton in Bulletin 45 of the U. S. Bureau of Mines, entitled, Sand Available for Filling Mine Workings in the Northern Anthracite Basin. It is estimated that the northern field contains 10,000,000,000 tons of these deposits, or a sufficient quantity to cover the 176 square miles of coal area to a depth of about 25 ft. These deposits of sand, etc., overlying the coal measures attain a maximum depth of more than 300 ft., and are usually saturated to such an extent as to render them semi-fluid. It is this condition of fluidity that limits the mining of coal seams cropping in or in close proximity to these deposits, and it is in the interest of safer and more efficient mining methods under these conditions that the study of this subject is here presented. The dangers incident to mining under deep deposits of sand have long been realized by operators in the northern anthracite field, and much has been done to prove the contour of the rock and vein croppings underlying these water-bearing deposits of sand and gravel. Although, as far as we know, the accidents of the past have not resulted in the loss of life, except in two instances, yet nearly all were attended with more or less miraculous escapes of men working in the vicinity of the breaks, so that the probable existence of pot holes, etc.,

Jan 1, 1915

By H. E. Williams

In view of the frequent occurrence of petroleum in other parts of the world, it seems odd that so large an area as is contained within the borders of Brazil should be without this product. This apparent deficiency may be due, however, to our ignorance of the regions in which it may exist. In some places, indications point to the probable existence of petroleum in ages gone by; and while the presence of petroleum pools may be problematic, in several regions conditions not unfavorable to their occurrence exist. Yet, Brazil has enormous oil resources in the rich oil-shales in different parts of the country. Many of these shales are very rich and only suitable processes for the extraction of the oil are lacking. At the present time, only a few small experimental plants are producing oil by distillation from these shales. These plants have been the subject of recent investigations by the Geological and Mineralogical Survey, a preliminary report of which is in the hands of the printer. The only regions where studies have not been made are the upper Amazon, the Acre, the Rio Negro, and the Peruvian frontier, which really seems to be the most promising field for explorations of any in the country. In the vast plateau region of the interior north of the 20th parallel of latitude, granites, gneiss, mica schists, and very old metamorphosed sedimentaries predominate. Later, sedimentaries occupy a minor position and, where found in the interior, represent a thin veneering resting on the older rocks. At several places near the coast they have a greater development and contain considerable beds of oil-shale and may, .in some cases, offer conditions favorable for the occurrence of oil. Such deposits are found in the Permian rocks of central and southern Maran-hao; in the Tertiary and Cretaceous beds along the coast of Alagsas Sergipe, Bahia, and perhaps farther south in Espirito Santo; and in the Parahyba embayment north of Cape Frio and in the interior Tertiary basin of eastern Sao Paulo.

Jan 1, 1921

By R. E. Reed-Hill

The shear continuity conditions under which one mechanical twin may cross another are considered. Twin intersections usually involve various types of slip deformation in addition to twinning. Because the shear of the crossing twin may be partly transmitted through the crossed twin by slip mechanisms, continuity of the twinning shear vectors is not required at a twin intersection. It is concluded that analyses based on twin intersections should not he used as an independent method for deducing twinning elements in newly observed twinning modes. WHEN one mechanical twin passes through another, a twin intersection is said to occur. In the simplest form of intersection, Fig. 1, the crossing of one twin by another is accomplished with the aid of a second-order twin induced, in the twin that is crossed, by the crossing twin. The subject of twin intersections is significant to the field of deformation studies because it has been postulated by cahn1 that twin intersections should occur only under the following continuity conditions: 1) the traces of the primary and second-order twin must be parallel to each other in the plane of the crossed twin; 2) the direction 771 and magnitude, S, of the twinning shear must be identical in the crossing and second-order twins; also, the sense of shear must be the same. If these postulates are valid they constitute a valuable tool for determining twinning elements of newly observed twinning modes in metals. In his classic paper in 1953 on the plastic deformation of a uranium, Cahn1 used these continuity conditions to deduce twinning elements for several uranium modes. However, in the same year, pratt2 showed that both of Cahn's continuity equations were violated for (1012) twin intersections in zinc. Later, Kiho and Maruyama3, 4 showed that Cahn's second postulate was violated in {301) and (101) twinning in tin and (101) twinning in bismuth. In spite of this documentation that Cahn's second postulate is often violated, several recent papers5'6 have been published which have attempted to use the condition of continuity of twinning shear vectors for the evaluation of twinning elements. The primary purpose of this paper is to call attention to the possible ambiguity inherent in applications of Cahn's postulate, and to present additional information concerning the nature of twin intersections.

Jan 1, 1964

By John T. Galey

Oil and gas development in southern Pennsylvania during 1937 was marked by considerably increased activity in deep-sand drilling. Nine tests were completed to the Oriskany sand: one in Independence and three in South Beaver townships, Beaver County; one in Franklin township, Butler County, two in Slippery Rock township, Lawrence County; one in Mt. Pleasant township, Washington County, which is drilling below the Oriskany, and one in Fairfield township, Westmoreland County. Two of these wells, both of which were in the Blackhawk pool, South Beaver township, Beaver County, obtained wet gas with open-flow volumes of 1.5 million cu. ft. and 3.1 million cu. ft. and closed-in pressures of 1900 Ib. The remaining seven were unproductive in the Oriskany. Two wells, one in Hampton township, Allegheny County, which is shut down temporarily as a result of a gas pocket, and one in South Beaver township, Beaver County, are drilling to the Oriskany. One deep test on the Chestnut Ridge anticline, South Union township, Fayette County, was completed after considerable difficulty as a dry gas well in the Onondaga limestone. At this locality the cherty limestone is porous as a result of fracturing. Three additional tests are under way in the area, one in South Union township, a second in North Union township, and a third in Wharton township. Completions Oil.—Despite price cuts and production curtailment of Pennsylvania Grade crude, caused largely by a decreasing demand from export markets, operation in the shallow oil areas continued at a fairly high rate and a number of good wells were completed. Some of these were new wells in close proximity to old production and others were old wells drilled into deeper pays. One new well of a number of producers drilled to the Nineveh Thirty-foot sand in the Harvey pool, Center township, Green County, made 400 bbl. of oil and 500 million cu ft. of gas the first 24 hr. The Chambers dam pool of Amwell and South Franklin townships, Washington County, yielded a number of Fifth Sand producers with initials as high as 200 bbl. Several wells in the old Mars-Butler field

Jan 1, 1938

By Charles W. Goodale

In the course of the preparation of my paper on " The Occurrence and Treatment of the Argentiferous Manganese Ores of Tombstone District, Arizona" (Dam., xvii., 767), my attention was called to two patents which have been issued for the use of a diaphragm at the upper end of a Howell furnace, whose importance merits more than a passing reference. Mr. J. K. Pardee invented and first put into use in the Algon quin mill, at Philipsburg, Mon., in 1880, a ('new' and useful im provement in rotary ore-roasting furnaces," which was intended "to increase the capacity, effectiveness and working economies of such furnaces." The following description and accompanying figures are taken from the patent papers, dated December 21st, 1880: Fig. 1 is a side elevation of the feed-end of the Howell rotary furnace, with parts broken away, the better to exhibit my invention. Fig. 2 is an end elevation of the same. Fig. 3 is an end elevation of the same, showing a modification of my invention. In operating a furnace of this kind, of the capacity of one ton of ore an hour, it was found that for the best work the two fire-places (one at each end of the revolv ing cylinder) consumed about ten cords of wood every twenty-four hours, and that about twenty-fonr tons of silver-ore were introduced through the feed-pipe. It was also found that of the amount of ore, fully one-third did not go through the revolv ing cylinder, but went into the dust-chanibers about the feed-end of the furnace or cylinder, and this ore going into the dust-chambers was found not to be sufficiently chloridized for amalgamation, but had to be re-roasted. I then caused to be made, out of boiler-plate iron, a segment of a circle, the height of which was about one third of the diameter of. the cylinder or furnace, the circumference of the circle being smaller than the circumference of the furnace, so that about a half-inch space would be left between the plate and the furnace, when said plate or segment was in position. This segment or plate of iron was then fastened to the bottom of the feed pipe, as shown in the drawings, wherein A represents the revolving cylinder or furnace; B, the fire-place and dust-chambers at the feed-end of said furnace; C, the inclined feed-pipe, and D, the diaphragm, partition, or plate fixed within said furnace, A. With the diaphragm or plate, D, in the position shown, the furnace was run for about a month, and it was found that with the furnace in best working condition only four cords of wood every twenty-four hours were consumed, that no fire was required at the feed-end of the furnace, that not one-twelfth of the ore

Jan 1, 1890

Abbott, Argyle Campbell 1209 Sherwin Ave., Chicago, Ill. Almstrom, Adne A., Student, Met. Engrg., Washington State College Pullman, Wash. Ankudinoff, N., School of Mines, Univ. of Utah Salt Lake Cite, Utah. Apter, Robert F., Student, McGill Univ Montreal, Que., Canada. Bailey, Donald G 798 Kensington Rd., Los Angeles, Cal. Baker, Kenneth B., Met., Aluminum Co. of America Pittsburgh, Pa. Barger, Thomas, Student, Univ. of North Dakota Grand Forks, N. D. Bartholomees, Geo. C Box 304, Bonne Terre, Mo. Bates, Walter, Student, Univ. of Utah, School of Mines Salt Lake Cite, Utah. Bobb, Russell V 16 College Ave., Houghton, Mich. Boswell, John C., Stripping Asst., Fairbanks Exploration Co Fairbanks, Alaska. Brandenburg, E. C., Student, Univ. of Kentucky 112 Church St., Lexington, Ky. Brannen, John, Chemist, Assay Office, Consolidated Min. & Smelt. Co. of Canada, Ltd., Tadanac, B. C., Canada. Brooker, Edgar, Jr., Student, Ferrous Met., Stanford Univ., Stanford University, Cal. Brooking, Leslie E 738 Lakoma, Norman, Okla. Clark, Martin Lester, Student, Missouri School of Mines Rolla, Mo. Collins, Edward D., Jr Box 1597, Ribbing, Minn. Comeau, Faye Bernard, Student, New Mexico State School of Mines Socorro, N. M. Conder, Henry S., Student, Pet. Engrg., College of Min., Univ. of California, Berkeley, Cal. Cotton, John Francis, Metallographist, Stealton Plant, Bethlehem Steel Corp., Steelton. Pa. Dahlgren, Elmer George, Student, Univ. of Wisconsin, Tripp Hall, Madison, Wis. Dale, James L., Student, Colorado School of Mines Golden, Colo. Dashti, Mirza Abdullah Khan, Graduate Student, Columbia School of Mines, Engrg. Chemistry, New York, N. Y. DeHuff, Gilbert L., Jr., Student, Lehigh Univ Bethlehem, Pa. de Romana, Enrique P., Jr. Engr Casilla 22, Arequipa, Peru. Oresbach, Charles Howard, Geol., Gulf Production Co Box 1428, Amarillo, Tex. Evens, Howard G., Student, Michigan College of Min. & Tech Houghton. Mich. Fassler, Glen Emerson Rodman, Inspiration, Ariz. Feight, Charles Donald, Foreman, Clairton By-Product Coke Wks., Carnegie Steel Co., 319 5th St., Wilson, Pa. Floe, Carl F., Student, State College of Washington Pullman, Wash. Fuentes, Vicente, Student, Pet. Engrg., Univ. of Oklahoma, School of Mines, Norman, Okla. Fuhrman, Carl F., Student, New Mexico School of Mines Socorro, N. M. Goergen, Gerald G., Cerro de Pasco Copper Corp Casapalca, Peru. Grove, Hubert A., Training Course, U. S. Aluminum Co New Kensington, Pa. Gastetter, Robert E 1010 N. Cherry Ave., Tucson, Ariz. Halbouty, M. T., Student, Texas Agriculturcl & Mech. College, Box 254, Faculty Exchange, College Station, Tex. Halfast, Edgar 710 E. Okmulgee Ave., Muskogee, Okla. Hall, Robert Lee 121 58th St., Niagara Falls, N. Y. Hanson, Rolf H., Student, Colorado School of Mines Golden, Colo. Hillyer. Shaler G., Student, New Mexico School of Mines Socorro, N. M. Hoertel, Frederick W., Met., R. W. Hunt Co., Engrs St. Louis, Mo. Holtz, Henry G., Student, Ohio State Univ Columbus, Ohio. Hon, Richard J Box 721, Miami, Ariz. Huffman, James O'Neil, Student, College of Min., Univ. of California Berkeley, Cal.

Jan 1, 1929

By Verne D. Johnston

ALTHOUGH the stocks of Lake Superior iron ore on dock or at furnaces at the beginning of the year were about 6,000,000 tons less than at the beginning of 1938, the steel industry was operating at only 52 1/2 per cent of capacity and continued at approximately this rate to about Aug. 1. Consequently the iron mines in the Lake Superior district during the winter and spring period were almost all on a curtailed production basis, governed mostly by the needs of the communities rather than by anticipation of ore demands. Many of these properties gave extra employment by prosecuting heavy strip- ping programs, and the underground mines by shaft sinking and rock development. All underground mines re- turned to full operation in September, mostly two-shift, five days per week. A few operated the sixth day. The ship- ping schedules were increased so that the actual delivery for the year exceeded early expectations by about 20 per cent. Final Lake shipments were slightly in excess of 45,000,000 gross tons.

Jan 1, 1940

By James K. Gluck, William E. Galloway, Gary E. Smith, John P. Morton, Christopher D. Henry

INTRODUCTION Surface mining and in situ leaching of uranium have the potential to alter ground-water quality around mines and leach sites. Of particular concern is the fate of uranium and its associated trace elements: molybdenum, arsenic, and selenium. We wish to under- stand the natural processes that control trace element concentrations in ground water and how these processes will influence dispersion of the elements from a mineralized zone, both naturally and during and after mining or restoration. For example, it is commonly recognized that the trace elements are soluble in oxidizing ground water but are insoluble, and can be precipitated, in reducing ground water. Thus oxidizing, metal-bearing water leaving a deposit could re- enter reduced ground, causing the water to be re- reduced and the trace elements to be, reprecipitated. In a sense, this is recreating the original mineralization process. To accomplish the above goals, we have (1) examined the theoretical controls of concentrations based on the available geochemical and thermodynamic data, (2) determined the major ion composition and oxidation-reduction status of Oakville waters because of the influence of these factors on trace element solubility, and (3) determined trace element concentrations and distribution in Oakville ground water. The last approach is used to evaluate how well actual behavior follows predicted behavior. This report focuses on two elements, uranium and molybdenum, because they exemplify the results obtained. The report also is restricted to a regional study of Oakville ground water. Results of more de- tailed study in and around major uranium districts in the Oakville and much of the raw data that support the conclusions in this report are presented in Galloway, Henry and Smith (1980). This report is part of that larger study, which concerned the depositional systems, hydrology, and geochemistry of the Oakville. The U.S. Environmental Protection Agency funded the study, under grant numbers R-805357-01 and R-805357-02. Theoretical controls were determined by reviewing the available literature on aqueous chemistry and behavior of uranium and molybdenum. To aid in under- standing water chemistry, Oakville water analyses were run through a modified version of the computer model WATEQF (Plumer, Jones, and Truesdell, 1976). WATEQF calculates speciation of dissolved ions and determines saturation with respect to a variety of minerals. In the discussion below, ion activity products (IAP) are compared with the equilibrium constant (KT) for various reactions and mineral products. Values of log IAP/KT near zero indicate that the water is in equilibrium with a mineral. Values less than -1 indicate considerable undersaturation and values greater than +1 indicate oversaturation. Galloway, Henry, and Smith (1980) give a more complete discussion of the application of this approach to Oakville water chemistry. Eh-pH diagrams have been constructed or adapted from the literature to predict what form -- dissolved ion or stable mineral species -- uranium and molybdenum assume under various conditions. Construction of the diagrams has followed procedures described by Garrels and Christ (1965). This approach is particularly appropriate because the solubility of the elements is Eh-dependent, and Eh varies greatly within the Oakville aquifer. A number of assumptions or approximations are inherent in the use of Eh-pH diagrams and chemical models such as WATEQF and in the interpretation of water chemistry in general. Both Eh-pH diagrams and chemical modeling rely entirely upon available thermo- dynamic data, including free energies of formation and dissociation constants for various reactions. These values are known to varying degrees of accuracy. Most major ions and minerals are relatively well control- led; however, data for trace metals are much poorer. Thermodynamic data are not available for some minerals, and for other minerals, two or more divergent values exist. By necessity, we have relied on the judgment of others to evaluate thermodynamic data. Calculations by WATEQF and constructions of Eh-pH diagrams are based on an assumption of equi1ibrium. Equilibrium may not be comnon in low-temperature aqueous environments; at best, ground-water composi tion may be in a state of dynamic equilibrium, continuously changing due to changes in environmental conditions. Eh-pH diagrams show what phases are stable at equilibrium under given conditions; they do not prove that the phases actually exist. Many minerals persist or form metastably under conditions outside their equilibrium stability field. The kinetics of reactions, which cannot be evaluated here, are important in determining what phases occur. Kinetics may be less of a problem for ground water that travels and evolves slowly through a semihomogeneous matrix than for many other natural systems. Eh-pH diagrams show equilibrium fields only of phases included. They do not indicate anything about stability relative to phases not included in the diagram. WATEQF, obviously, cannot calculate the degree of saturation of a mineral not included in the program or for which the appropriate ions were not analyzed. Thus, a mineral that was not considered may be the most stable phase under a given set of conditions and may control the solubility of a trace element. Also, this study is limited exclusively to in- organic compounds. Organic material is known to be an

Jan 1, 1980

By Ma Guang, Huang Jinshou

In this paper we briefly describe measuring techniques and their practical use in the mining industry of China. A strain coefficient matrix of triaxial strain cell for a flat ended borehole is also introduced.

Jan 1, 1983

By J. B. Clark

In multiphase ternary diffusion studies, plots of the variation bf the composition on the isotherm constitutes one of the most effective methods of presenting experimental results, especially if such plots are made in a manner which relates the composition path on the isotherm with the diffusion layer structure in the couple. Unfortunately, if different conventions for plotting are used serious misinterpretations occur readily, causing apparent disagreement between investigators who actually share the same viewpoint. A common convention for mapping these diffusion paths is needed at this time because with the increasing use of the electron-probe X-ray microanalyzer, a much greater number of ternary diffusion studies can be expected in the near future. In an effort to prevent unnecessary confusion in the future litera- ture, a convention for these plots is proposed, as outlined below. A hypothetical example of the use of these conventions is given in Fig. 1 where the path of composition through the diffusion structure of the 100 pct A/50 pct B, 50 pct C couple is plotted on the appropriate isotherm of the ABC system. The lower case letters relate the region in the diffusion layer structure to the appropriate composition on the ternary isotherm. 1) The diffusion path is plotted on the isothermal section corresponding to the diffusion temperature of the couple. 2) The terminal compositions of the plotted diffusion path are the initial compositions of the couple halves—provided infinite boundary conditions are maintained. If, in either couple half, infinite conditions are not maintained, then the path terminates at the composition of the exterior surface of the couple. If, at this surface, the composition varies with time or if the plotted path is time dependent, then the diffusion time should be noted beside the plotted path. 3) A solid line crossing a single phase field (e.g., line a-b in Fig. 1) denotes an existing layer of that phase in the diffused couple. 4) A dashed line crossing a two-phase field parallel to the tie lines (e.g., line g-h) represents an interface between the two phases with interfacial compositions designated by the ends of the tie-line. The line represents no spatial extent. 5) A solid line crossing a two-phase field so as to cut tie lines (e.g., line b-c or line j-k) represents a locally equilibrated columnar two-phase layer. The solid line should cut those tie lines which correspond to the lateral interfacial equilibria along the columnar

Jan 1, 1963

By J. G. Bouwkamp

This paper presents three general approaches towards the solution of the stress distribution and the behavior of tubular connections as used in offshore well drilling structures. First, the possibilities of using plastic models and photoelasticity techniques in evaluating the stress distribution in gusset plate connections are analyzed. The results of photoelastic studies on the stress distribution in the in-plane gusset plate of two-dimensional joints are presented. The influence of the configuration of the gusset plate (with and without cut-outs) is discussed. Second, the paper deals with recent developments and applications of computer programs to analyze connections with directly inter-welded tubes and with gusset plates. The possibilities and limitations of these programs are discussed. Stress patterns analyzed with these programs are presented for different joint configurations. Finally, the basic test procedures and results of a test on a tubular joint under static and alternating loads are discussed. INTRODUCTION The effective design of tubular connections as encountered in offshore well drilling towers or floating platforms has been complicated basically by the radial flexibility of the tube walls. This flexibility is a source of severe stress concentrations which can initiate an early failure of these joints. In an attempt to reduce the influence of the wall flexibility of the column tube, certain joints are presently designed by inter-welding the incoming branch members. In those designs, the force acting normal to the chord tube can be reduced considerably. A second group of joints incorporate gusset plates or stiffening rings to stiffen the column wall and to distribute the incoming branch member forces over a larger part of this wall. A third approach to improve the stress distribution in a tubular joint is to increase the wall thickness of the column member. This can be achieved by simply applying a thicker wall section in the vicinity of the joint. A fourth possibility to restrain the radial flexibility of the tube wall is to fill the column member with concrete. Also, a single, cast steel seat welded to the column tube can be used to improve the stress distribution in this wall. Although all these designs improve, in general, the state of stress in the column wall, the altered stiffness often causes the development of critically stressed areas in the web members. At the same time the actual design in most instances is decisively influenced by the site which governs the depth and controls the forces produced by waves, earthquakes and ice flow. Also, the towing, erection and foundation requirements of offshore structures can affect the actual design selection. Because of the complexity of the structural configuration of tubular joints, the stress analysis of these connections has necessarily been based on simplified and often crude assumptions. For the earlier and smaller type of connections with about 4-ft diameter column sections, the primary problem was to evaluate the relative stiffness of the column wall section and the load transfer between joint members. Due to the recent developments of offshore drilling structures with increasingly larger connections (e.g., column diameter. 32 ft; web members, 8.5 ft) this problem has become even more critical. One design philosophy for such large joints follows a member-to-member connection with radially heavy reinforced column sections. This radial stiffness can be attained by closely spaced and intensively stiffened horizontal diaphrams together with vertical stiffeners. A second solution incorporates a concrete-filled section between the outer and inner walls of the column tube. Another philosophy considers large gusset-plated joints. The problem in these joints is to develop an effective load transfer between the branch tubes and the gusset plate and to minimize the stress concentrations in the member walls as effectively as possible. Several concepts are followed to achieve this gradual transfer between web-member walls and gusset plates. Because the number of joints in these huge platforms is limited compared to the over-all size, a proper design of these joints is even more important than was the case for the many joints in the smaller, but multi-legged towers. A failure of one of those ultra-large joints could well cause the complete collapse of such a structure. Under these circumstances an accurate analysis of the large joints is of the greatest importance, together with information regarding the expected behavior of such joints under critical alternating load conditions. Recent applications of photoelastic model techniques have proved to be quite effective in evaluating the elastic behavior of such joints. Although a complete study of such connections is quite well possible with present-day photoelastic techniques, it might often be feasible and necessary to limit the objectives and to restrict these investigations to the study of a specific aspect of the joint. Another very promising avenue of approach to solve the complex stress pattern in these connections seems to be the recent development of digital computer programs. In this category, cylindrical shell programs and finite element methods for more complex configurations have

Jan 1, 1967

By B. B. Bucky

THIS investigation was carried on by means of models and the applica-tion of the principles of similitude to determine the effects of props, props and cribs and sand filling in longwall mining. The geologic structure and rate of face retreat were kept constant and the only change introduced was in the method of support. It is not felt necessary to repeat a description of apparatus, or to explain the fact that a scalar model made in all parts of the same material as the prototype will behave similarly to the prototype when rotated at speeds such that the centrifugal force is as many times the gravitational force as the prototype dimension is a similar linear model dimensions. The reader is referred to earlier papers1,2 for further information regarding these statements. All models were made of sandstone and were as in Fig. 6. They are composed of a 3/16-in. ore body bed A, overlain by a 3/16-in- bed B, a 3/8-in, bed C and two 1/8 -in. beds D and E. The model was rotated at ±2350 r.p.m. equivalent to a model ratio of 1268. It was worked back 1/4 in. at a time before being replaced in the centrifuge and again rotated. Table 1 gives model and prototype dimensions occurring in this discussion, the prototype dimensions being 1268 times the model dimensions. Figs. 1, 2, 3 and 4 were taken while the model was rotating at 2350 r.p.m. One was taken for each face retreat of 26.4 ft., but for obvious ,reasons all are not presented. Fig. 1 (A-E) shows the behavior of this type of structure with face retreats of 26.4 ft, and no artificial support. Fig. 2(A-E) shows the behavior of this type of structure where breaker and face props were used. The props were exceptionally strong, being of steel 1/8 in. square in cross section, and capped with 1/16 in. ± of soft wood and paper, to allow for roof deflection. The face props were

Jan 1, 1939

By C. E. Sims, G. A. Lillieqvist

The following presentation is more a summation of observations made and conclusions drawn over a period of three to four years than a report of experiments made with a definite objective. Tests were made, of course, to verify hypotheses, but the large mass of data was collected incidental to other work. Lack of space forbids the presentation of more than a few of those data. On the other hand, it is unfortunate that some of the most illustrative examples are not available. The work is admittedly incomplete but is presented in the hope that it will stimulate further work along a similar line. The answers to many of the questions left unanswered by this paper will be found only after long and painstaking study, such as is scarcely possible in a commercial laboratory where problems of immediate importance consume most of the time. It is also hoped that this study will in some measure throw light on some of the dark spots of steelmaking, and help to clarify some of the annoyingly vague references to "good practice." Only cast steel was studied and the conclusions apply to cast steel, but it is the authors' opinion that the quality of rolled or forged steel is largely dependent on the quality of the ingot, which is a casting. Although this discussion deals almost entirely with inclusions, it is important that the reader understand that only those natural inclusions which owe their origin to the solubility of certain materials in steel and to the chemical reactions of steelmaking are considered. Accidental inclusions, such as entrapped particles of slag, nozzle, runner, or mold arc outside its province and are not considered. Such accidental inclusions are always dangerous and should be carefully avoided. Relation between Ductility and Nonmetallic Inclusions In September, 1928, an acid electric furnace was put into operation at the Indiana Harbor plant of the American Steel Foundries. Following the usual practice, aluminum additions were made in order to obtain sound castings. Immediately the problem of low ductility arose. Previous to that time, only open-hearth steel was produced, and, aluminum being used rarely in that steel, there had been practically no trouble with low ductility in the lower carbon range.

Jan 1, 1932

By John A. Church

AT a time when the treatment of gold and silver ores by fusion, in opposition to the mill-process, is attracting so much attention in this country, it may be useful to consider what is done in a well-conducted foreign work. For this purpose I will ask the reader to accompany me to Lend, in Austria, a small but thoroughly organized

Jan 1, 1873

By D. K. Crampton

Internal stress and season cracking in brass have been studied for many years and the technical literature contains many data on various phases of the subject. A resume of the literature shows certain fairly well established points upon which various authors are mostly agreed: 1. Season cracking is primarily caused by the presence of relatively high internal stresses, or possibly in some cases by external stresses, or both. 2. A specific corrosion is also essential to season cracking. Certain agents, particularly mercurous salts, mercuric salts and ammonia salts, have such a specific corrosive effect. 3. The tendency to season crack under given conditions increases with increasing zinc content, brass containing less than 20 per cent. zinc being relatively immune. 4. In alpha brass the season cracks are intercrystalline; in alpha-beta brass they lie between the two constituents; and in beta brass they are transcrystalline. 5. The ordinary impurities or added elements in special brasses have little or no effect on the tendency to season crack. 6. Internal stresses can be eliminated, or at least reduced to a safe limit by annealing treatments at temperatures that do not produce visible microstructural changes or appreciable softening of the worked brasses. There are, however, some points in connection with the phenomenon of season cracking which have not been thoroughly investigated, or wherein different authors and investigators are not entirely in agreement. The investigations described in this paper were undertaken to determine: 1. The correlation between mercurous nitrate tests and actual season cracking on long-time atmospheric exposure. 2. The quantitative effect of type and degree of drawing operations on the intensity of internal stress and on the tendency to season crack in brass tubes. 3. The possibility of drawing high-brass tubes in such a manner as to prevent the occurrence of harmful stresses rather than to find a remedy for such stresses once having obtained them.

Jan 1, 1930