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By William P. Blake

The late Dr. Ebenezer Emmons of Albany, one of the geologists of the Survey of New York and the author of The Taconic System, brought to notice as early as 1838" a peculiar concretionary and lamellar form of phosphate of lime, to which he gave the name Eupyrchroite, from the Greek words for fire and color, with the pefix

Jan 1, 1893

By D. Gupta, S. Weinig

This investigation comprises the study of dislocation-oxygen interactions in a! titanium and its effect on the ductile to brittle transition in titanium. Internal friction techniques using a low-frequency lorsion pendulum were used to study the oxygen atom interactions with dislocations in "superpurity" titanium. A calculation of the interaction energy between an oxygen atom and a dislocation, based on the "breakaway" strain resulted in a value of 0.015 ev as compared to theoretical values of 0.022 and 0.035 ev for edge and screw dislocations, respectively. Both the saturation of the room temperature decrement and the transition from ductile to brittle behavior occurred at 1.5 at. pct 0. It was proposed that the embrittlement was due to oxygen atoms immobilizing the dislocations. It was possible to increase the ductility of the Ti-0 binary alloys by decreasing the oxygen pinning. The increase in uniform elongation was 30 pct for an increase in the preanneal temperature of 300°C. ThE room-temperature ductility of a titanium is significantly affected by interstitial solutes. Although oxygen has a solid solubility of 15.5 pct by weight, the room-temperature ductility extends only to 0.6 pct.' The ductility precipitously falls at this concentration and the fracture characteristics change from ductile to brittle.2 The small effective bulk composition of solute required to destroy the room-temperature ductility of the titanium must be indicative of an in-homogeneous distribution of solute atoms. Internal friction techniques were used in this investigation to

Jan 1, 1960

By F. W. Luerssen, J. F. Elliott

F LUSHING the early slag from a stationary open Fhearth having a high percentage of hot metal in its charge is necessary in order to remove silica from the system. The flush slag is strongly oxidizing and is somewhat acidic. It has, however, considerable capacity to extract phosphorus from the bath and it also removes considerable manganese. It seems probable that factors which control the distribution of phosphorus and manganese between slag and metal in the refining period also should be dominant in the flush and postflush periods. Several studies, as summarized elsewhere,1,2 support the viewpoint that conditions closely approaching equilibrium for these elements are rather readily established during the refining period. Over the years these studies have repeatedly demonstrated that 1—high slag v01ume, 2—low bath and slag temperature, 3—basic slag, and 4—strongly oxidizing slag favor rapid elimination of phosphorus from the bath to the slag. They also show that the following conditions favor retention of manganese in the bath: 1—low slag volume, 2—high bath and slag temperature, 3— basic slag, and 4—minimum oxidizing power of slag. When it is considered that the flush slag often carries as high as 75 pct of the manganese charged and only 25 to 60 pct of the phosphorus charged, it is evident that in removing silica much manganese is sacrificed but phosphorus removal is far from conplete. Because of overriding circumstances, this is accepted in most operations and actually it is considered to be inevitable. This may account for the fact that little attention has been paid to conditions affecting the elimination of phosphorus and manganese in the flush slag. A recent study of the behavior of various charge oxides has developed considerable information on the flush and postflush periods. Because the data are felt to be of general interest, they have been brought together and Presented in this paper. The object is to show the various factors in the flush and postflush periods which influence elimination of phosphorus and manganese. Physical Conditions During and After Flushing Physical conditions existing during the flush vary from plant to plant, from shop to shop, from furnace to furnace, and even from heat to heat. They are strongly influenced by the physical and chemical character of the charge oxide which is ordinarily necessary to provide sufficient oxidizing power early in the heat. Invariably the period is characterized by a vigorous reaction between the principal re-actants: the hot metal being added and the charge oxide. During the flush, it is probable that the slag acts to some extent as an oxidizer; but, because of the critical influence of the behavior of the charge oxid'e on flushing action, it seems apparent that the oxide itself is the dominant oxidizer. Fig. 1 shows the course of two heats which were selected as being typical of the group studied. Heat A was charged with 55 pet hot metal, based on the total metallics charged, and heat B had 57 pct hot metal. As indicated in Table I and Fig. 1, the melt-down slag, which is not usually voluminous and which is principally FeO, expands greatly in volume and will show rather high levels of SiO2, MnO, and P2O5 very soon after the beginning of the hot metal addition. Simultaneously, large volumes of CO are liberated which cause violent mixing of slag and metal. It is of interest to note that the time required to bring carbon down to a low level is very much longer than that required for the removal of silicon, manganese, or phosphorus. At the end of flush, carbon in the bath is still approximately 2 pct. When strongly reducing hot metal is brought into contact with strongly oxidizing conditions within the furnace! it is probable that the rate of mass transfer to the slag (and atmosphere) of silicon, manganese, phosphorus, and carbon initially depends principally on the rates at which the two participating phases are brought into contact That is, it depends on the nature of the various reactions. Later in the flush period, when the scrap is virtually all dissolved and the action of the bath has settled down to a steady and somewhat gentle boil, it is likely that other factors, such as the transfer of oxygen across the slag-metal interface, become dominant. The temperature of the slag-metal system is far from uniform. Heat is being driven by the flame down through the slag. Bubbling and surging of the metal also frequently brings portions of the bath in contact with the flame. At areas of contact between the ore and liquid metal, or slag and liquid metal, the oxidizing reactions generate much heat. On the other hand, scrap is being melted which tends to absorb large quantities of heat. Because the liquid bath is high in carbon, the steel scrap is brought into solution rapidly. This can proceed at a rather low temperature; and until much of the scrap has been taken into solution, the bath temperature would not be expected to increase appreciably. Consideration of these factors leads to the conclusion that during the flush period the slag should be rather hot and the bath relatively cold. Both observation and temperature measurements bear this out. Experimental Data The extended program of charge oxide evaluation permitted study of the widely varying conditions existing during the flushing period. Slag and metal analyses and bath temperatures reported herein (Tables I and 11) were obtained toward the latter portion of the work. Four different types of charge oxide, sinter, two types of hydraulic cement-bonded soft ores, and a pyrobonded agglomerate were used in the study. Although the heats reported were from only one 205 ton furnace, they show variations in flush slag analyses all the way from 25 pct FeO, which is typical with the use of a hard natural charge ore, to 45 pct FeO which resulted when a very poorly agglomerated fine ore was used. The physical behavior of the flushes showed a correspondingly wide variation from well controlled reactions to violent surges following periods of inac-

Jan 1, 1956

By Oliver Bowles

GLASS razor blades, glass chairs, and marble window panes attest that creative genius was still active in 1935. Many less striking, though doubtless more important, developments are to be recorded for the nonmetallic mineral industries, and not the least of them is the establishment of an Industrial Minerals Division in the A.I.M.E. under the able leadership of Samuel H. Dolbear, Chairman. Thus the nonmetallics are rightly granted equal dignity with metals and fuels in the category of mineral industries. The brief review of progress that follows merely touches the fringe of important developments in this broad field.

Jan 1, 1936

By S. K. Tarby, A. E. Rathke

A series of 0.21 pci carbon steel melts was processed under conditions which sinzulated industrial vacuum degassing practices. The results indicated that the efliciency of carbon deoxidation was not significantly increased by vacuunz degassing at chamber pressures below 100 torr. The two common phenomena of vacuu?rz carbon deoxidation, i.e.,an unaccountable carbon loss and nonequilibrium deoxidation, were observed in this study. Oxygen from adsorbed and chenzically combined water of certain refractory structures was probably responsible for the unaccourttable carbon drop. The nonequzlibrium deoxida-tion phenomenon was adequalely correlated by a bubble nucleation )mechanism. Although the major limiting factor in oxygen removal from these melts contained in alumina crucibles could not be eslablished with certainty, there was some evidence that melt-refractory interactions were not the most imp-portant limiting factor. CONSIDERABLE attention has been given to the use of carbon in conjunction with vacuum degassing* as a deoxidation technique. An advantage of utilizing the reaction: for deoxidation purposes is that the reaction product is gaseous and hence can be effectively removed from the melt. The pressure dependency of Eq. [I] is illustrated by the expression for the thermodynamic equilibrium constant, K: where pco is the partial pressure of carbon monoxide, and hc and ho are, respectively, the Henrian activities of carbon and oxygen in molten steel. The thermodynamic aspects of the C-0 reaction in molten Fe-C-0 alloys have been investigated extensively. Theoretical predictions based on Eq. [2] indicate that, at the chamber pressures reached in most vacuum degassing units, carbon is the most effective deoxidizer that can be obtained. ~ornak' has compared industrial values of carbon and oxygen contents with values calculated from theory, and has shown that on a commercial basis vacuum carbon deoxidation has not achieved the degree of success that is predicted from theoretical considerations of the C-0 reaction. The use of industrial units to determine the reason for this deviation is limited by economics and the difficulty in controlling critical process variables. Therefore laboratory-sized experiments in this area should yield valuable information. Investigations on vacuum carbon deoxidation have been made in experiments conducted under vacuum induction melting conditions where pressures in the low micron range, long treatment times, exposure to highly dynamic vacuum conditions, and relatively quiescent bath conditions have been maintained. Inve~ti~ators~~~ utilizing vacuum induction melting for the production of high-purity iron by carbon deoxidation have concluded that, under high vacuum conditions, melt-refractory interactions constantly supply oxygen to the melt. Thus, it has been suggested that refractory dissociation rather than the C-0 reaction establishes the lowest possible oxygen content of a melt. Thomas and Moreau4 and Bennett, Protheroe, and ward5 have studied carbon deoxidation of Fe-C alloys melted in magnesia crucibles under reduced pressures. The results of both studies differed considerably from those predicted by theory, and the limiting factor for lower oxygen contents was attributed to melt-refractory interactions. Because the refractory material used in both investigations was magnesia, no quantitative measure of crucible reaction could be made and the amount of carbon consumed during treatment was utilized as an indirect indication of the extent of crucible reaction. Studies concerned with the determination of the minimum oxygen content attainable in pure iron and Fe-C alloy material vacuum-induction-melted in various crucible materials have also been conducted."' The suitability of a crucible refractory for use under vacuum conditions appears to depend upon the major refractory constituent, the amount and type of impurity oxides, and the composition of the melt. Meadowcroft and Elliott9 have presented a theoretical review of the type and extent of various refractory reactions which should be considered in vacuum refining. ~eadowcroft'~ considered the vacuum degassing process to be dependent upon the "carbon boil" and has proposed that a part of the difference between the experimental and theoretical results for vacuum carbon deoxidation may be explained by the fact that the pco term in Eq. [2] is not the chamber pressure. Instead, the pressure necessary for carbon monoxide

Jan 1, 1970

By H. E. Cline, D. F. Stein

A fine lamellar structure with interlamellar spacings ranging from 0.I to 3.7 was Woduced by high-speed directional solidification and used to study the interaction of dislocations with an array of bimetallic bound-am.es. The tensile flow properties were measured at elevated temperatures and the results interpreted in terms of an image force model. As the width of the plates decreases the strength increases according to a Hall-Petch relation, suggesting pile -ups. Considerable strengthening was also observed at elevated temperatures. In recent years composites containing a strong but brittle phase and a ductile but weak phase have been studied extensively in the search for a high-strength material with adequate ductility.' However, the strength of these composites has been limited to a volumetric average of the strengths of the component phases. In this paper we will show that a composite made by directional solidification of a Cu-Ag eutectic has strength properties that substantially exceed the strength of either of the metals in the composite, and an explanation for this increased strength will be presented. The Cu-Ag eutectic is a near ideal material to study for several reasons. The eutectic structure is made up of alternate plates of silver-rich and copper-rich phases with the same crystal structure.2'3 In addition, the mechanical and elastic properties of silver4 and copper5 are known over a wide range of temperatures and the eutectic microstructure is stable to nearly the melting point.6'7 Therefore, the properties of the eu-tectic are readily comparable to various theories involving the mechanical properties of copper and silver. The experiments consisted of producing directionally solidified Ag-Cu eutectic material, determining the structure and performing tensile tests at different temperatures and strain rates. EXPERIMENTAL A) Solidification and structure. A cylindrical ingot 2.2 cm in diam and 15 cm long was prepared from 99.999 pct pure materials and cast in argon. The ingot was placed in an alumina crucible and was direc-tionally solidified at 7 x 10"4 cm per sec in a Bridg-man apparatus in argon. Metallographic examination at both ends and along the length of the ingot showed a uniform structure that consisted of fine alternate plates of silver- and copper-rich phases. The plates were aligned parallel to the growth direction, as shown in the longitudinal section, Fig. 1, and were in small randomly oriented domains of parallel plates as viewed in a transverse section, Fig. 2. Four smaller ingots 0.175 in. in diam were solidified at speeds of 2Xlo-', 4.4 xlo-', 4.4 x 10-3, and4.4x10-4 cm per sec to produce a range of lamellar spacings. Replica electron micrographs were taken to resolve the individual plates as shown in Fig. 3. The copper-and silver-rich plates in the larger ingot were about

Jan 1, 1970

By R. B. Gilmore

The North Texas district, as herein defined, includes the counties of Archer, Baylor, Clay, Cooke, Foard, Hardeman, Jack, Kiiox, Montague, Wichita, Wil-barger, and Young. Jack and Young Counties are included for the first time so that this district will correspond with District No. 9 of the Texas Railroad Commission. This area covers generally the crest and south flank of a system of buried mountains known as the Red River uplift. The oil and gas accumulations along this feature are in traps, which, although localized by structures incident to the regional uplift, usually are modified by stratigraphic changes in the sediments. The structural deformation caused by the Red River uplift is modified by the Rend arch, which is a broad anticline plunging northward from the Llano uplift in central Texas through Young and into Archer Counties. The fields in southern Archer, southeastern Baylor, southwestern Clay, and western Jack Counties arc on the extreme north end and along the flanks of the Bend arch and have generally the same type of oil and gas accumulation as the other fields in this district. Recent exploration has been along the flanks of the Fort Worth syncline, which is east of the Bend arch and south of the Red River uplift and extends into southeastern Clay and southwestern Montague Counties and along the eastern part of Jack County. The larger part of past oil and gas produc- tion has come from Pennsylvanian strata, with less important amounts lrom the Permian, and minor quantities from the Mississippian and Ordovician. Developments during 1943 About 1100 wells were drilled in the district during 1943 and more than 500 oil wells were completed, an increase from 1942. of approximately 12 per cent in the number of successful drilling operations of the total wells drilled. The addition of Jack and Young Counties to this district accounts for part of this increase, almost 150 wells being completed in the two counties. Production increased slightly over the previous year as a result of an increase in the number of producing wells and a greater demand for this high-gravity, sweet crude oil. The average depth of discovery wells was about 400 ft. deeper than in 1942. Although more discoveries produced from horizons below the base of the Strawn series than from those above the Straw, the deeper horizons, including the Bend series of the Pennsylvanian, the Mississippian limestone and Ellenburger of the Ordo-vician, largely were dissappointing from the viewpoint of major additions to oil reserves. The largest single addition to the reserves was in the basal Strawn sand in the Walnut Bend field, Cooke County. During the year, 31 wells were completed, both in the field and as cxtensions. The most active arca Was Jack County, in which five fields or potential fields were discovered, although only 44 oil wells were completed.

Jan 1, 1944

By R. B. Gilmore

The North Texas district, as herein defined, includes the counties of Archer, Baylor, Clay, Cooke, Foard, Hardeman, Jack, Kiiox, Montague, Wichita, Wil-barger, and Young. Jack and Young Counties are included for the first time so that this district will correspond with District No. 9 of the Texas Railroad Commission. This area covers generally the crest and south flank of a system of buried mountains known as the Red River uplift. The oil and gas accumulations along this feature are in traps, which, although localized by structures incident to the regional uplift, usually are modified by stratigraphic changes in the sediments. The structural deformation caused by the Red River uplift is modified by the Rend arch, which is a broad anticline plunging northward from the Llano uplift in central Texas through Young and into Archer Counties. The fields in southern Archer, southeastern Baylor, southwestern Clay, and western Jack Counties arc on the extreme north end and along the flanks of the Bend arch and have generally the same type of oil and gas accumulation as the other fields in this district. Recent exploration has been along the flanks of the Fort Worth syncline, which is east of the Bend arch and south of the Red River uplift and extends into southeastern Clay and southwestern Montague Counties and along the eastern part of Jack County. The larger part of past oil and gas produc- tion has come from Pennsylvanian strata, with less important amounts lrom the Permian, and minor quantities from the Mississippian and Ordovician. Developments during 1943 About 1100 wells were drilled in the district during 1943 and more than 500 oil wells were completed, an increase from 1942. of approximately 12 per cent in the number of successful drilling operations of the total wells drilled. The addition of Jack and Young Counties to this district accounts for part of this increase, almost 150 wells being completed in the two counties. Production increased slightly over the previous year as a result of an increase in the number of producing wells and a greater demand for this high-gravity, sweet crude oil. The average depth of discovery wells was about 400 ft. deeper than in 1942. Although more discoveries produced from horizons below the base of the Strawn series than from those above the Straw, the deeper horizons, including the Bend series of the Pennsylvanian, the Mississippian limestone and Ellenburger of the Ordo-vician, largely were dissappointing from the viewpoint of major additions to oil reserves. The largest single addition to the reserves was in the basal Strawn sand in the Walnut Bend field, Cooke County. During the year, 31 wells were completed, both in the field and as cxtensions. The most active arca Was Jack County, in which five fields or potential fields were discovered, although only 44 oil wells were completed.

Jan 1, 1944

By Herbert Hoover

THE Federation of Engineering Societies has been created for the sole purpose of public service. This initial meeting surely warrants some discussion of a few of the problems to which this organization, for expression of the --. engineering mind, can quite well give consideration. Some of the greatest of the problems before the country and, in fact, before the world, are those growing out of our industrial development. The enormous industrial expansion of the last fifty' years has lifted the standard of living and comfort beyond any dream of our forefathers. Our economic system under which it has been accomplished has given stimulation to invention, to enterprise, to individual improvement of the highest order, yet it presents a series of human and social difficulties for the solution of which we are groping. The congestion of population is producing subnormal conditions of life. The vast repetitive operations are dulling the human mind. The intermittency bf employment due to the bad coordination of industry, the great waves of unemployment in the ebb and flow of economic tides, produce infinite wastes and great suffering. Our business enterprises have become so large and complex that the old personal relationship between employer and worker has to a great extent disappeared. The aggregation of great wealth, with its power of economic domination, presents social, economic ills which we are constantly struggling to remedy.

Jan 1, 1920

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

By Donald D. Carr, Lawrence F. Rooney

Perhaps no other mineral commodity in this volume has as many uses as limestone and dolomite. These carbonate rocks are the basic building blocks of the construction industry, the material from which aggregate, cement, lime, and building stone are made. Carbonate rocks, and their derived products, are used as fluxes, glass raw material, refractories, fillers, abrasives, soil conditioners, ingredients in a host of chemical processes, and much more. Although the use of limestone and dolomite goes back before recorded history, new uses and products are continually being found. Carbonate rocks form about 15% of the earth's sedimentary crust and are widely available for exploitation. Found extensively on all continents, they are quarried and mined from formations that range in age from Precambrian to Recent. Reserves of carbonate rock are large and will last indefinitely, although high-purity deposits may be absent or have limited avail- ability in certain areas. Limestone and dolomite are so useful and so abundant that in 1972 more than 690 million tons were produced in the United States. In fact, about 75% of all stone quarried or mined in the United States was carbonate rock. Sand and gravel was the only mineral commodity produced in greater quantity. In this chapter we have sought to provide the general reader an overview of carbonate rocks, their composition, distribution, production, and uses, with emphasis on developments since 1960. In doing so we borrowed extensively from our recent report on the applied geology of limestone and dolomite (Rooney and Carr, 1971). The literature on the limestone and dolomite resources of the United States and Canada is so vast and diverse that one can easily become mired down in print. We tried to list those references that are easily accessible and that provide the economic geologist with a starting point for more intensive study. The table listing selected references on limestone and dolomite resources in Canada and the United States reflects our attempt to be selective rather than exhaustive and to direct the reader to the best sources of detailed information.

Jan 1, 1975

By L. O. Bacon

IN the spring of 1952 Calumet and Hecla Inc. began a geophysical program near Shullsburg, Wis., in the Wisconsin-Illinois lead-zinc district, to assist the geological and drilling exploration programs. Sphalerite, the ore mineral in this area, occurs with a considerable amount of marcasite. In general the higher the percentage of sphalerite in the ore, the higher the percentage of marcasite; however, there may be mineralized zones high in marcasite but low in sphalerite. Orebodies in general are relatively narrow and elongated. Reconnaissance exploration of virgin areas consisted of drilling along lines at 500 to 1000-ft intervals. Whenever a mineralized zone was intersected additional drilling was done to determine whether or not the zone carried zinc percentages of ore grade and, if so, to delineate the body. Calumet and Hecla Inc. was interested particularly in a method that would show the direction and position in which to drill from the original discovery hole. This suggested a method of contacting the orebody, which occurs at depths ranging from 100 to 200 ft, with one electrode. After a number of procedures had been considered it was decided to use equipotential line methods. Instrumentation and Field Procedure: The power source used was a 400-cycle Signal Corps motor-generator having a rated output of 1200 w at 115 v. The detection unit consisted of test probes, a two-stage amplifier, and &apos;head phones for determining the equipotential line by audio null. Field procedure consisted of contacting the sulfide body in the hole by a specially built spring-loaded expanding electrode which would be lowered into the hole, in the closed. position, until it reached the mineralized zone. At that point the mechanism was released so that the arms would make contact with the walls of the hole in the same manner that a well-bore caliper does. This electrode was then connected to the generator, the other terminal of which was connected to the surface electrode. The surface electrode was either a point, a straight line, or a circular line electrode. The point surface electrode was placed at a considerable distance from the hole, that is, 2500 to 5000 ft, depending somewhat upon the depth to the sulfide zone and the distance from the hole containing the subsurface electrode to which exploration was considered. A higher voltage output from the power source would have been desirable, although no difficulty was encountered in determining null points to a distance of 500 ft. Straight line electrodes used were approximately 1000 ft in length at a distance of approximately 1000 ft from the hole containing the subsurface electrode. The circular line electrode used consisted of 4400 ft of bare No. 10 copper wire, which provided a circle of 700-ft radius. All line electrodes were fastened to the ground at 20-ft intervals with copper staples 4 in. long. Equipotential points were determined at 25 to 100-ft intervals. Location of the points was made by plane table and stadia. In open country with a three-man crew, the points were plotted as they were determined. With a two-man crew, pegs were placed at equal potential points and surveyed in after several equipotential lines were determined. Although interpretation of results given in this paper is qualitative, the paper as a whole would not be complete without a discussion of the theoretical distribution of potential due to a circular line electrode. The theoretical distribution would be required if a quantitative interpretation of the measured potential distribution were to be made. The theoretical potential distribution due to a circular line electrode can be obtained by means of Legendre polynomials. Using the method as developed by Weber,&apos; the potential for a circular line electrode in a semi-infinite, homogeneous, isotropic medium can be expressed, using the spherical coordinate system, as: V(r,n) = pi/2pR[S(r/R)nPn(cos?)Pn(cosa)]r<R [1] er V(r,a) =pI/2pr[S(r/R)Pn(cos?) Pn(cosa)]r>R [2] where: 0 is the angle at the origin, taken on the axis of the circular electrode between the axis and the line drawn to the circumference of the circular electrode. a is the angle between the axis and the radius, r.

Jan 1, 1957

By John H. Bassarear, Harold W. Sorstokke

The never ending search for lower unit costs led Pima Min- ing Company&apos;s management to study various alternatives shortly after Expansion III was completed. A considerable amount of ore as- saying 0.35% copper had to be moved to maintain mill feed at the desired 0.54 % copper content, which is the overall grade of the ore reserves. Detailed investigations revealed that for a period of 8-10 yr, about 14,000 tpd of 0.30- 0.40% copper ore pass the crusher enroute to the low grade stockpile. This ore is very hard, very clean and has to be mined at a uniform rate. A six month pilot plant run testing autogenous and semi-autogenous grinding gave encouraging results. Since no mining costs need to be charged to the extra tonnage (it had to be mined anyway), the major costs would be against milling. The decision to proceed was made in August 1970. Fluor-Utah was retained as the prime design construction contractor. Ore was put through the new mill on December 29, 1971. By March of 1972 design tonnage

Jan 5, 1973

By Frank M. Brooks

Endeavoring to meet the requirements of more oil created by the war effort, the oil industry of Kansas in 1944 maintained a level of exploratory and development work well above the average of previous years. During the year, 1866 test wells were drilled, of which 838 were completed as new oil wells, 89 as new gas wells and 939 as dry holes. These figures compare with 895 new oil wells, 32 new gas wells and 834 dry holes for a total of 1761 tests in 1943. Thus, there was a marked decrease in the number of new oil wells, and an increase in the new gas wells and dry holes. The total daily initial potential of production discovered by the successful wells amounted to 494,689 bbl. of oil as compared with 736,297 bbl. in 1943. The increase in unsuccessful tests and decrease in the daily initial potential of production has caused considerable comment and speculation among the oil operators of the state. This tends to confirm the fact that each year it is becoming harder to find the remaining oil fields. The total number of wildcats drilled in Kansas was 651 in 1944, including the so-called "extension wildcats" (more than 1/2 to I mile from known production). Of this number, 410 are classified as "rank wildcats," being more than one mile from production. The total of 651 compares with the total of 577 for 1943, showing an increase in wildcat drilling of 74 test wells: Of these tests, 81 were successful in finding new oil fields or substafitially extending known areas of production, and 20 either found new gas pools or extended old ones. The ratio of dry holes to producing wells among the "rank" wildcats was approximately 10 to I (372 dry and 38 successful). This compares with a ratio of 10 to I in 1943, 11 to I in 1942, and 6 to I in 1941. A compilation of the results obtained by 34 active companies, including all of the major companies, reveals that their efforts accounted for 286 rank wildcat wells, of which-37 found oil or gas, making a dry-hole percentage of 87. Approximately 55 per cent of all, tests (pool and wildcat) were failures. Thc Kansas Nomenclature Committee of the Kansas Geological Society named and classified 43 new oil fields and 8 new gas fields during the year. The discovery wells of the new oil fields had a total initial potential of 18,358 bbl. for a per well average or&apos; 427 bbl. The average initial potential per well in 1942 and 1943 was 894 and 419 bbl., respectively. With nearly all wells producing at their economic capacity, the total production for Kansas during 1944 totaled 101,896,704 bbl., which compares with total runs of 107,709,679 bbl. in 1943. Production of natural gas during 1944 reached a new high record of 135 billion cubic feet. This compares with 122 billion cubic feet for 1943, and 98 1/2 billion cubic feet for 1942. The large Hugoton field of Southwestern Kansas accounted for about half of the total gas produced. Highlights OF the Year Although 51 new fields were found in the state during 1944, it is apparent that the

Jan 1, 1945

By George H. C. Norman

A NUMBER of methods have been developed for the determination of the dust concentration in air, some of which have been reported as very efficient and for research may be more satisfactory than the method about to be described. In practical mine use, however, the accurate research equipment is unwieldy and requires a high degree of technical skill to manipulate it. Also, it gives less general practical information to the operator in the same length of time than the method described here. Moreover, it is doubtful whether at the present stage of affairs the results obtained from the precise methods have any more practical significance than those obtained with simpler and more portable apparatus, which can rapidly give a sufficiently reliable indication of the relative dust hazard. HISTORY OF DUST DETERMINATION IN ONTARIO The first record of mine-dust determination in Ontario is given in an article by Dr. J. H. Elliott,&apos; in which he records a few dust counts made with the Palmer spray apparatus. There were insufficient data from which to draw any definite conclusions or reasonably compare with present-day counts using the konimeter. The first konimeter dust sampling was started in the Porcupine district in 1926, using light-field counting without adhesive and with no sample treatment before counting. A method of semidark-field counting was used from about 1928 to 1931 and dark-field illumination was adopted permanently about December 1931. The konimeter has been continued as the principal means of dust sampling in the mines of Ontario, where South African practice has been adopted because in South Africa most careful study has been given the problem of silicosis, and very complete records of work done there are

Jan 1, 1937

A FACT not generally understood about the Engineering Societies Library on Thirty-ninth Street in New York -in particular, not realized by many of the great indus-tries of the country-is that it is a free public institution. To utilize its valuable facilities one does not have to be a member of the national engineering societies (which shoul-der its financial deficit each year). Anyone, at any place in the world, can use the library. A man in California, or in South America, or in Persia, can write or cable to the Library staff and receive information on the same basis as any engineer living in New York. For example, a few months ago an American mining en-gineer in China needed additional geological information about a district which he was about to explore. He cabled his need to the Engineering Societies Library and the next steamer brought him the data he wanted. A phosphorus company in Alabama wished to obtain a translation from the Norwegian of an article on cement which they had heard about. They wrote to the Engineer-ing Societies Library; the article was located, and a trans-lation made and sent them.

Jan 12, 1927

By Sheldon P. Wirnpfen

AN extensive study of German underground manufacturing experience is being undertaken by the Air Materiel Command. Headquarters officials consider completely underground facilities one of the most effective means of protecting aircraft production against air attacks of the strength and type employed in World War II. Advantages accruing to underground manufacturing installations other than protection are, perhaps, a smaller maintenance problem and the possibility of using gravity flow on some production lines. Offsetting these advantages are the high cost of construction, problems of ventilation, and poor acoustics. Excavation costs might well be less than the cost of enclosing the same area on the surface, as new and better methods of rock drilling and transportation are developed. Certainly the amount of building materials used would be far less than in constructing a surface plant of the same dimensions. A fewer number of skilled workers would be required to perform the labor of excavation. Underground construction would

Jan 1, 1947

By Hiroshi Oikawa, A. G. Guy

Recent experimental evidence has shown that it is often incorrect to neglect the reactions occurring at an interface with respect to the diffusion reactions. By introducing reaction-rate constants and k for the transfer of components 1 and 2 between the a and b phases, a phenomenological description has been devised for the coupled processes of diffusion and in-terfacial reaction. An illustrative example has been analyzed with the aid of a suitable computer program. The results indicate that for kab values on the order of 10&apos;1 cm per sec and Ð values of about 10¯10 sq cm per sec, the interfacial reactions are significant during the first 10 2 to l0 6 sec of a diffusion experiment. Among the observable effects of the interfacial reactions in this case appear to be the burying Kirkendall markers and an anomaly in the initial shifting of these markers. THE study of diffusion between two phases is especially important because of its direct connection to phase transformations. For example, the transformation of austenite to ferrite involves diffusion in the a and ý phases and also an interfacial reaction (trans formation) at the a/? interface. If ferrite and aus-tenite are the two members in a diffusion couple, the same two reactions occur during the diffusion process. The numerical values obtained for the diffusion coefficients and interfacial-reaction constants from diffusion experiments can then be employed to predict phase-transformation behavior. Refinement of the calculations of phase transformation is also suggested by the present method for treating two-phase diffusion. In the recent paper by Nolfi et al.&apos; only the solute com ponent is considered in the interfacial reaction accompanying a phase transformation. The present analysis demonstrates that both components must be considered. It is generally recognized that reactions of some kind must occur at the interface in a two-phase diffusion couple, but usually it is assumed that the interface reaction occurs so rapidly that its effect on the overall process is unobservable because the slower diffusion process determines the kinetics of the process. However, Seith and Heumann 2 pointed out that effects of the interfacial reaction should always occur in the early stages of diffusion, and recently Eifert et al. 3 have shown that interfacial reactions influence the composition and motion of the interface in a/ß Al-Cu diffusion couples during the entire course of prolonged, high-temperature treatments. A general procedure for handling the combined processes of interfacial reaction and diffusion in a binary, two-phase system is to introduce kinetic coefficients for the interface reactions and to develop the system of equations governing the interlinked processes of diffusion and interface reaction. The resulting equations, although not amenable to solution in closed form, can be usefully manipulated by a digital computer. INTERFACIAL REACTIONS IN TWO-PHASE DIFFUSION Consider the general case of diffusion between two solid solutions, a and ß, which are adjacent phases in a binary system, Fig. 1. Two semiinfinite bars having compositions c1 and c0ß are jointed at x = 0. If concentrations are expressed in volume fraction,4

Jan 1, 1970

By L. Himmel, R. F. Mehl, C. E. Birchenall

The rates of self-diffusion of iron in artifically prepared wustites of various compositions have been determined using the decrease in surface activity technique. Similar measurements are reported for artificial magnetites of nearly stoichiometric composition and for natural hematite single crystals. These data, together with appropriate thermodynamic data derived from the present study or from the literature, are used to calculate the rates of oxidation of iron and its oxides, taking as a basis the theoretical rate equations developed by Wagner. The calculations are compared with experimental rate constant data for these same reactions and are shown to provide essential confirmation for the Wagner theory. For the most part, the results are also consistent with the previously proposed transport mechanisms in the oxides of iron. WHEN a metal is exposed to an oxidizing atmosphere at elevated temperatures, a superficial oxide layer is formed which then thickens according to some characteristic rate law. Provided that the oxide layer is dense and continuous and does not present any paths for gaseous diffusion, continued growth must inevitably involve the migration of the reactants—either the metal or oxygen or both—through the lattice of the solid oxide. This is true whether the reaction rate is controlled by the diffusion process itself or by a slow step in a reaction at one of the interfaces. If the overall rate is limited by diffusion, and if the concentrations or thermodynamic activities of the reactants at the boundaries of the oxide layer are independent of time, the familiar parabolic rate law is observed. Under these conditions, Wagner1 has shown that the rate constant may be expressed in terms of the mobilities of the reacting components and the appropriate concentration or activity gradients which are established across the growing oxide layer. In presenting the phenomenological basis for the theory, Wagner has emphasized the role played by lattice defects in diffusion processes in oxides. The essential validity of this theory has been confirmed by experiment for a number of simple systems including the growth of Cu2O on copper.&apos;-&apos; One of the objectives of the present study has been to extend the Wagner approach to the more complex process of the oxidation of iron and its oxides, and particularly to wustite, which is normally the major constituent of the oxide scales formed on iron at temperatures above approximately 570°C. For this purpose the rates of self-diffusion of iron in w?stite, magnetite, and hematite have been measured by tracer techniques and the necessary thermodynamic data have been obtained from equilibrium studies involving the oxides and their atmospheres. These data have subsequently been used to test the underlying assumptions of the Wagner theory as well as the detailed mechanism of the scaling of iron previously proposed by Davies, Simnad, and Birchenall.5 Lengthy treatments of diffusion and conduction phenomena in ionic crystals have been published." * The latest, by Jost,8 also summarizes much of the existing experimental data. In general, however, the oxides of iron have not been considered specifically and hence a brief review of the available

Jan 1, 1954

By AIME AIME

PAST President R. C. Allen, then State Geologist of Michigan, gave George Corless his first job-tracing ?magnetic? with the dip compass in northern Wisconsin. His second job was also with a man now Past President of the Institute-"Chief" Buehler, for whom he worked at Joplin three years. Then came seven years as geologist and later as assistant manager of the Chanute Spelter Co., a subsidiary of The American Metal Co., Ltd. His entrance into the oil business was not planned. During a lull in the zinc industry in July, 1926, he stopped at Houston, after a trip to the Rio Grande Valley, and was so impressed with the city that he decided to migrate. His first job there was with the Texas Company, whose impressive building across from the Post Office caught his eye after he had mailed a letter saying that he was settling in Houston and would not be home until Christmas. Some months later, A.I.M.E. Past President Philip N. Moore learned that he was in. Houston and wrote an unsolicited recommendation that resulted in his present employment with the Humble Oil & Refining Co. Today he is superintendent of the Gulf Coast Division of its production department. The Division extends from Jackson County, Texas, to New Orleans, and includes such pools as Sugarland, Conroe, Toni Ball, Thompsons, Anahuac, and Friendswood. -

Jan 1, 1938