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Prospecting methods used in Tennessee have gradually improved with the years, as required by depletion of the easily accessible and shallow deposits and the universal trend toward mechanization, and as necessitated by exploring deeper beds, often occurring under limestone and flinty overburden. In the early days it was a very simple matter to dig pits by hand, using a plentiful supply of local farm labor to expose relatively shallow deposits of "brown rock" under shallow clayey overburden that would stand up without timbering. Visual inspection of the exposed phosphate and expert judgment of the "grade" analysis, aided by a "biting" test to reveal presence of unwanted silica, furnished most of the information required. All this might be helped by a few samples sent to the local chemist† who supplemented his income by judicious trading or tanning a few bear skins. The extra curricula activities did not affect the accuracy of the analysis which hold up even under present day standards. Some shot and core drilling was done in Hickman County, mostly for the limestone-like blue Phosphate deposits. The next step was the use of a 4-in. posthole auger, hand operated as described by Guenther, followed by a completely mechanized rig, as described by Pickard. Both these methods are practically adapted to the prospecting of the relatively soft brown rock deposits at moderate depths of clay overburden. For prospecting in areas of deeper overburden, such as are often found in Hickman County, up to 150 or even 200-ft depths, a modified core-drilling method is described by Guenther. Johnston describes a special diamond-drilling technique, developed by TVA, to penetrate flint horizons, which was adopted by the International Minerals in chemical corporation to prospect in Hickman County where deposits had previously been prospected at considerable expense and with difficulty, by small, temporary, hand-dug shafts.

Jan 1, 1948

By G. L. Corrigan, J. R. Coleman

Four factors that largely determine the end product obtained when cement and water are mixed are the chemical compo ition of the cement, the fineness to which the cement is ground, the amount of mixing water used, and the procedure used in mixing the slurry. In order to study the effect of two of these factors, the other two, the chemical composition and method of mixing, are kept constant, leaving as variables fineness and water-cement ratio. Through years of experimentation and usage it has been well established that the reduction of cement clinker to a very fine state by grinding improves its cementing value, principally because the reaction between cement and water takes place only at the surface of the cement particle, further action being hindered by the accumulation of reaction products that tend to coat the unreacted material. Therefore, the more finely ground a cement, and the greater the surface exposed in proportion to its mass, the more rapid is the hydration rate. Similarly, the greater the surface exposed, the greater the proportion of the cement that reacts, and the lower the amount of residue that is unreacted and so remains inert and unable to make any contribution to cementing properties.1 Although it is more expensive to manufacture a finely ground cement than a coarser cement, the advantages of fine grinding of construction cements were so marked that the fineness of cement has increased considerably in past years. When the manufacture of special oil-well cements was begun, it was necessary to consider properties of cement that previously were considered of minor importance, foremost of these being pumpability. Since, with the water-cement ratio constant, a finely ground cement will produce a neat slurry of higher consistency and shorter time of pumpability than will a coarser cement, there is a tendency to grind oil-well cements to a lower degree of fineness. Therefore, in order to produce oil-well cements that will make a slurry having a long time of pumpability, cements are manufactured that because of their coarseness generally are poorer cementing materials than some of the more finely ground construction cements. On the other hand, often it is necessary to pump oil-well cements for long periods of time to place them properly behind a string of casing in a deep well, and since high strength is not of foremost importance for such cement, there is room for considerable controversy concerning the proper fineness range.

Jan 1, 1941

By A. E. Nehrenberg

R. A. Schmucker, Jr.—The writer wishes to point out that an acicular growth of austenite, similar to that described in the author's paper, was recently observed in an alloy steel of only 0.06 C content. This steel, which represents an 0.07 max C, 1.35 Cr, 0.55 Ni, 0.20 Mo analysis, combines the characteristics of minimum hardness in the annealed condition with maximum hardenability and is therefore suited primarily for cold-hobbing applications. The acicular austenite formation in this steel was observed accidentally during a determination of its Ac1 temperature. The samples used in this investigation represented as-forged bar stock which had been given a preliminary temper at 1300°F. The critical (Ac1) temperature was finally established at 1400 °F. Fig. 15 represents the microstructure of the sample which had been heated at 1450°F for ½ hr, water quenched, and tempered at 600°F for ½ hr (for the purpose of darkening the martensite). It will be observed from the distribution of the darkened areas of martensite that the parent austenite grains formed at 1450°F had grown in an acicular manner and still occupied only a small percentage of the total area. The remainder of the area contains the original equiaxed ferrite grains in which new austenite had as yet scarcely formed. However, the tiny isolated martensitic patches at several points where three or more ferrite grains intersect indicate that small austenite grains had formed and started to grow in an apparently equiaxed fashion. Fig. 16 represents the prior microstructure of an original sample in the as-forged and tempered condition, before it was heated -above the critical temperature. It is probable that there are two kinds of ferrite in this structure: (1) The equiaxed proeutectoid ferrite grains which separated from the austenite when the steel was cooled from the forging temperature, and (2) the acicular ferrite associated with the aggregate of fine carbide which is represented by the patches of

Jan 1, 1951

By S. Stutz

Coal, like most other minerals, only exceptionally occurs in a sufficiently pare state to he directly available for general manufacturing purposes. And even where this is the case, the small coal or slack is usually more impure than the lump coal, as the slate, clay, etc., from the roof and bottom of the vein become mixed with it in the handling it undergoes. These impurities often exceed ten or more per cent. in addition to the impurities of the coal itself. The most common impurities of the coal are slate, or shale, clay, and sulphur. The latter occurs in different forms, but moat frequently as bisulphide of iron, or iron pyrites, and as sulphate of lime, or gypum. In both cases the impnrities add greatly to the amount of ash, and where they are present in considerable quantities the raw coal, and still more the coke made from it, is unfit for the manufacture of iron. Coke will coutain on an average at least fifty per cent. more ash and sulphur than the ram coal from which it is made. To the manufacturer of iron every additional per cent. of ash which his coal or coke contains is a source of additional expense, seemingly small, and yet very important in the aggregate. In the blast-furnace, for instance, the ash must be heated up to the melting-point, and, since it is composed largely of refractory substances, the consumption of carbon in melting it will be equal to at least one-half of its weight; that is, a certain part of tile coke is consumed for the melting and fluxing of the ash and is lost. Besides this, it is well enough known to the iron-master that coke containing lees ash makes the &lag or cinder more liquid and less incliner1 to stick to the walls of the furnace. Fuel containing much sulphur produces generally a white iron, poor in carbon, while from the same ore arrd flux, with a pure fuel, a good foundry iron might be obtained. The work of separating slate, sulphur, etd, from the coal has as yet only been successfully accomplished by the washing process. This process depends for its success on the differences in the specific

Jan 1, 1881

By A. R. Amos, S. B. Patterson

Log washers have been used for many years in the washing of clay iron ores, phosphate rock and manganese ores, but not until the past 15 years have they been employed to any extent in the preparation of aggregate materials and fluxing stone. For a machine of such importance where tenacious clay or soft rock must be eliminated, there are few data generally available. The purpose of this paper is to set forth the results obtained from several operations, together with a few suggestions for planning a specific installation. Where the material to be washed out consists of loose surface soil, silt, or small amounts of quickly soluble clay, there is little competition with other forms of washers, because greater power and maintenance are required for the operation of log washers, but where the foreign matter is a stiff clay, such as occurs with high-calcium limestones and in marginal gravel deposits, the ability of other kinds of washers to eliminate completely the hard clay balls is at least uncertain. Then the log washer comes into its own field, for with the breaking and churning action of the logs it will clean out the toughest clay. Even with material from the hydraulic dredge, if it contains tough clay, the log washer is desirable unless the gravel is subjected to a costly soaking and rehandling process. Recently there has been a considerable development in other types of machines to accomplish these results but it is not within the scope of this paper to make comparisons between competitive types, but to present the best obtainable data on log washers only. From the primitive design that gave it its name, a long log hewn from a tree, with paddles forged to shape from strap iron and attached by lag screws, the log washer has gradually been developed to the present all-steel type. As now manufactured, the log washer consists essentially of two built-up logs on which are mounted a series of paddles, carried by shafts fitted at the ends of the logs on bearings fastened outside the enclosing steel box, or trough, which is set at an angle of about 5" to 10" and into which the material is fed. Stuffing boxes at the places where the shafts pass through the box at the lower end are equipped with water-

Jan 1, 1938

By T. N. Williamson

6.3-1. Historical Development. Rotary drilling has been used in surface mining for many years. Its principal use is for primary blasthole drilling. In this use, holes in the range from 4 to 15 in. in diameter are drilled in overburden and massive ore bodies for large initial blasting operation. With properly designed shot patterns and loading, secondary blasting is seldom required. The use of rotary drilling with diamond bits for exploration is discussed in Chapter 3.1. Small rotary drillholes of approximately 2-in. diameter are employed as blastholes to shatter uncovered coal seams, but this is a minor part of surface mining drilling operations. Another minor use of rotary drills in surface mining is for placing wire saw poles in dimension stone quarries, usually accomplished with large-diameter calyx or steel shot drills. Primary blasthole drilling by the rotary method was performed with drag bits until 1949 (19). Its use in mining was only in soft formations, so that rotary drills prior to that time were found principally in overburden drilling for the surface mining of coal. In 1949 it was found that air circulation to remove cuttings resulted in increased penetration rate and prolonged life for the rolling-cutter type of bits. Prior to that time, and since their introduction in oil well drilling in 1907, water had been used for circulation with these bits. The dependence on water to clean the hole had delayed the acceptance of bits with rolling cutters in mines because of water haulage and freezing problems as well as the loss of water through cracks in the formation. After rolling cutters were introduced, subsequent improvements in tools made rotary drilling adaptable to harder formations (18). This system is now used in the hardest formations encountered in mining. 6.3-2. Principles of Operation. ENERGY. Rotary drills attack rock with energy supplied to the bit by a rotating drill stem, and infrequently by

Jan 1, 1968

By J. H. Henderson, J. Naar

The displacement of a wetting fluid from a porous medium by a non-wetting fluid (drainage) is now reasonably well understood. A complete explanation has yet to be found for the analogous case of a wetting fluid being spontaneously imbibed and the non-wetting phase displaced (imbibition). During the displacement of oil or gas by water in a water-wet sand, the porous medium ordinarily imbibes water. The amount of oil recovered, the cost of recovery and the production history seem then to be controlled mainly by pore geometry. The influence of pore geometry is reflected in drainage and imbibition capillary-pressure curves and relative permeability curves. Relative permeability curves for a particular consolidated sand show that at any given saturation the permeability to oil during imbibition is smaller than during drainage. ' Low imbibition permeabilities suggest that the non-wetting phase, oil or gas, is gradually trapped by the advancing water. This paper describes a mathematical image (model) of consolidated porous rock based on the concept of the trapping of the non-wetting phase during the imbibition process. The following items have been derived from the model. 1. A direct relation between the relative permeability characteristics during imbibition and those observed during drainage. 2. A theoretical limit for the fractional amount of oil or gas recoverable by imbibition. 3. An expression for the resistivity index which can be used in connection with the formula for wetting-phase relative permeability to check the consistency of the model. 4. The Iimits of flow performance for a given rock dictated by complete wetting by either oil or water. 5. The factors controlling oil recovery by imbibition in the presence of free gas. The complexity of a porous medium is such that drastic simplifications must be introduced to obtain a model amenable to mathematical treatment. Many parameters have been introduced by others in Iprogressing" from the parallel-capillary model to the randomly interconnected capillary models independently proposed by Wyllie and Gardner3 and Marshall4. To these a further complication must be added since an imbibition model must trap part of the non-wetting phase during imbibition of the wetting phase. Like so many of the previously introduced complications, this fluid-block was introduced to make the model performance fit the observed imbibition flow behavior. THE IMBIBITION MODEL ASSUMPTIONS The following assumptions are common to many two-phase models previously described. 1. The wetting characteristics of the medium are clearly defined. 2. When two fluids co-exist in the medium, the wetting phase will fill the smaller pores and the non-wetting fluid the bigger ones. 3. The pores have a circular cross section. 4. Apparent pore radii are related to the capillary pressure (drainage) by

By Herbert K. Kutter

This paper is concerned with the physical phenomena in the fracture process of presplitting and only indirectly with the establishment of the optimum presplitting parameters. Its nature is therefore qualitative, rather than quantitative. Before examining the problem of presplitting, it is first necessary to study the phenomena which occur when an explosive charge is detonated in a borehole. To do this it is desirable to consider the action of the explosion wave separately from that of the expanding gases.l In the theoretical analysis such a separation poses no problems. Experimentally this was accomplished by use of an underwater-spark discharge to generate the stress wave and by pressurized oil to simulate the pressure of the explosion products. The main role of the wave is to generate a densely radially fractured zone around the borehole. The subsequent gas pressure, exerted against the walls of a highly (radially) fractured cavity, generates a quasi-static stress field (henceforth referred to as static stress field). This stress field was found to be the same as that of a pressurized cylindrical "equivalent cavity" with a radius equal to that of the crack tips. Under these conditions the quasi-static stresses become appreciable and cause further extension of the radial cracks. It was further found that, under gas pressure, the longest of the radial cracks would extend first, and extension of two diametrically opposed radial cracks requires the least pressure. From these observations concerning the single shot the transition to a whole series of more or less simultaneous shots, as in presplitting, can readily be made. In the case of multiple shots, as in presplitting, exactly the same effects occur, but at numerous locations and sufficiently close in time that they interfere with

Jan 1, 1968

By Carl F. Floe, Michael B. Bever

THE possibility that carbon may be soluble in copper to a limited extent has been recognized for over a century. The quantitative investigation of this problem, however, requires more sensitive techniques than have formerly been available. Three recent developments have made possible more accurate determinations: the vacuum-fusion method of analysis, the production of copper of high purity and the availability of high-purity refractories, particularly graphite. In addition to its obvious theoretical interest, the problem of carbon solubility in copper is of practical importance. In the production of copper and of high-copper alloys, carbonaceous covers are frequently used. If even minute amounts of carbon are dissolved, insoluble carbon oxide gases will be formed when such metals are poured under oxidizing conditions. A mechanism of this kind could well be one of the principal causes of gas porosity in casting copper-base products. REVIEW OF LITERATURE In 1823 Vivian1 raised the question as to whether copper by overpoling becomes "combined with a minute portion of carbon." Karsten2 asserted, in 1832, that carbon reduces the high-temperature strength of pure copper, so that when the carbon content has reached 0.2 per cent the metal will be brittle at a dark red heat. According to Karsten, carbon contents of o.05 per cent make it difficult to hot-work copper. He also reported that the specific gravity of copper is 8.8969 and that it increases to 8.92 58 if the copper is cemented with carbon and then melted. He emphasized the difficulty of determining analytically the small amounts of carbon present in copper. The metal was removed by wet methods and the residue considered as carbon. At Percy's request, Dick,3 in 1856, carried out various working tests on copper that had been in prolonged contact with carbon, and found that the working properties of the metal had not been affected. He also attempted to determine the presence of carbon analytically. In one experiment the copper was dissolved and the residue was fused with litharge, and in another essentially a combustion analysis was made on a copper sample. In a final experiment, a sample was dissolved and the residue subsequently subjected to a combustion analysis. Indications of as much as o.005 per cent carbon were found, but Dick considered his work inconclusive largely because of the possible interference of sulphur. Percy4 concluded, from Dick's experiments and from some experimental work of his own, that the solubility of carbon in copper had not been established with

Jan 1, 1945

By Toshihisa Adachi, Shosei Serata, Shunsuke Sakurai

The present state of knowledge of three-dimensional rock properties does not provide an adequate basis for evaluating the safety of under- ground structures in situ. Most of the triaxial studies reported in the past have dealt with crushing strength, but have failed to consider the intergranular behavior and triaxial strain state of rocks. Without this information, the structural competence of rocks cannot be accurately assessed. The absolute three-dimensional testing method (ATT) was conceived for the purpose of analyzing the three-dimensional states of stresses and strains in aggregate rocks under conditions commonly encountered in underground structures. In-situ stress-strain states are not simple, even in the simplest possible form of opening, excavated in a homogeneous and isotropic rock medium. In general, there are four basic stress-strain states which are present in underground openings, regardless of the complexity of their geological conditions. They are the yielded, brittle-fractured, stress-relieved, stress-concentrated states, as illustrated in the schematic diagram, Fig. 1. The ATT machine was designed to create and study all these states in the laboratory. A theory describing the aggregate behavior of rocks under these diversified states is essential to evaluate the safety of underground structures. The Griffith theory is limited to tensile failure of ductile materials and therefore does not apply to behavior of aggregate rocks under compression. The Griffith theory also fails to consider the grain boundary characteristics of aggregates, which is the determining factor of rock behavior. The Mohr-Coulomb theory of failure ignores the importance of the intergranular behavior of rocks. An application of the continuum theory to

Jan 1, 1972

Prospecting methods used in Tennessee have gradually improved with the years, as required by depletion of the easily accessible and shallow deposits and the universal trend toward mechanization, and as necessitated by exploring deeper beds, often occurring under limestone and flinty overburden. In the early days it was a very simple matter to dig pits by hand, using a plentiful supply of local farm labor to expose relatively shallow deposits of "brown rock" under shallow clayey overburden that would stand up without timbering. Visual inspection of the exposed phosphate and expert judgment of the "grade" analysis, aided by a "biting" test to reveal presence of unwanted silica, furnished most of the information required. All this might be helped by a few samples sent to the local chemist† who supplemented his income by judicious trading or tanning a few bear skins. The extra curricula activities did not affect the accuracy of the analysis which hold up even under present day standards. Some shot and core drilling was done in Hickman County, mostly for the limestone-like blue Phosphate deposits. The next step was the use of a 4-in. posthole auger, hand operated as described by Guenther, followed by a completely mechanized rig, as described by Pickard. Both these methods are practically adapted to the prospecting of the relatively soft brown rock deposits at moderate depths of clay overburden. For prospecting in areas of deeper overburden, such as are often found in Hickman County, up to 150 or even 200-ft depths, a modified core-drilling method is described by Guenther. Johnston describes a special diamond-drilling technique, developed by TVA, to penetrate flint horizons, which was adopted by the International Minerals in chemical corporation to prospect in Hickman County where deposits had previously been prospected at considerable expense and with difficulty, by small, temporary, hand-dug shafts.

Jan 1, 1948

By Edwin Ludlow

For many years, coal has been known to exist in the valley of the Sabinas river, in the State of Coahuila, and for about 15 years it has been worked by the Mexican International Railway Co., which opened mines for its own fuel-supply when the railway was built, and has been mining continuously ever since. The coal-basin worked by this company lies along the Sabinas river, principally on the SW. side. It covers a wide area and has been carefully prospected, but only in a few parts have the beds been found sufficiently thick and regular for economical operation. This Sabinas basin was considered the only one in this field, until, in the Spring of 1899, the Las Esperanzas basin was found by Messrs. J. L. Elliot and E. D. Peters, who were in Mexico looking after some copper-properties. After a further examination by Mr. James T. Gardiner, of New York, the Mexican Coal & Coke Co. was organized in June, and active work was begun on Nov. 5, 1899. The coal-field of Las Esperanzas, situated in the State of Coahuila, about 85 miles SW. of Eagle Pass, Texas, adjoins and runs parallel with the Sabinas basin—an anticlinal separating the two outcrops by about 2 miles. Fig. 1 is a sketch-map of a part of the basin. The coal-formation is in the Upper Cretaceous, and corresponds with the Laramie measures of the United States. The following geological section, taken in Nogales canon, shows the measures between the massive limestones forming the Sierra de la Santa Rosa and the outcrop of the coal: Section. Feet. Limestone,...Unknown. Blue shale,.........110 Shale and sandstone,.. 60 Bed of fossiliferous shale,. 60

Jan 1, 1902

By M. M. Austin

Pure metallic tantalum, from a practical standpoint, is one of the newer developments in the metal field. Although it was used as filament in incandescent lamps in 1906, only within the last, five years has the metal been available in sufficient quantity and suitable form for more general application. In addition to corrosion-resisting properties and high melting point, the metal has an ability to withstand unusual amounts of cold working. It affords some striking demonstrations of block movement during plastic flow. Strength and Ductility of Tantalum Since there is no good way of defining working properties numerically, illustrations will be used. It is possible to roll a bar of pure tantalum 0.4 in. thick to sheet 0.001 in. thick, without heating or annealing. The sheet produced will be sound and may be bent upon itself at right angles to the direction of rolling. Longitudinally the sheet will be somewhat brittle. A disk of annealed metal may be cupped and drawn to the form of a capsule 3/16 in. dia. by 146 1? in. long. If carefully handled this capsule can be further deformed by drawing to a tube having an outside diameter of 0.050 in. Disks of tantalum may be spun into tubes of 39 in. dia. and 1½ in. long. In the form of rod, reductions may be made from 0.4 in. to 0.001 dia. In the latter process, it is necessary to heat the wire four or five times to 500" C., at intervals between 0.040 and 0.001 in. Although the melting point of tantalum is 2850" C., these heatings at 500" C. are sufficient to distinctly anneal it. Published figures on the strength and ductility of tantalum are not particularly accurate. This is due to the fact that these properties vary widely, depending on the extent to which the metal is contaminated by gas. There are no sharp critical points in these changes with gas content; samples of metal will vary from a springy or actually brittle condition to one of leadlike softness. Samples that have had a prolonged heating at high temperatures in a good vacuum, under conditions such as would be provided in vacuum-tube experimentation, will yield a product of about the hardness of annealed copper. The usual commercial metal will have the hardness of annealed mild steel.

Jan 1, 1930

By W. W. Smeltzer

The linear formation rates of wustite films have been determined over the temperature range 590° to 1030°C using a vacuum microbalance technique. These rates are dependent directly on the partial pressure of carbon dioxide, Activation energies for film and scale formation in carbon dioxide and oxygen atmospheres are equivalent to either the dissociation energies of carbon dioxide and oxygen, or the activation energy for the diffusion of cation vacancies in wustite. Of the metals, iron is the most widely used basic constituent of durable alloys despite its intrinsic property of converting at a relatively rapid rate to the oxides from which it is derived. This property has accounted partially for many investigations on the oxidation of iron at low and high temperatures. Interpretation of the results have been complicated by formation of multilayers containing the various oxide phases. To aid in elucidation of the oxidation kinetics, measurements have been carried out in this investigation on the growth of the wustite surface layer. There are several studies directly related to the objective of this investigation. The growth of multilayer scales has been demonstrated to be diffusion controlled in oxygen at atmospheric pressure over the temperature range 450" to 1200°C by Davies, Simnad, and Birchenall.' To gain an insight into the diffusion mechanism, Himmel, Mehl, and ~irchenall' determined the self-diffusion coefficients of iron in wustite, magnetite, and hematite. These results were used to evaluate the oxidation rates of iron and its oxides, taking as a basis the theoretical parabolic rate equation developed by Wagner., The evaluations were compared to experimental data and were shown to provide essential confirmation of this theory. Fischbeck, Neundeubel, and salzer4 have demonstrated that the oxidation of iron in carbon dioxide and other atmospheres at high temperature obeys a linear relationship. Because the Arrhenius temperature coefficients of the reaction rate constants changed at the A, point they concluded that the passage of iron into the oxide controlled the reaction. This viewpoint has been accepted by Benard and ~albot' to explain the occurrence of linear rates in oxygen before the onset of diffusion-controlled parabolic oxidation. This basic premise of a rate-controlling reaction at the iron/oxide interface has been questioned recently by Hauffe and Pfeiffer.' Since the formation of wustite may follow a linear or parabolic relationship depending on the pressure of the gaseous re-actant, they propose that linear oxidation is determined by a chemisorption reaction while parabolic oxidation is controlled by diffusion. As confirmation of this viewpoint, Hauffe and pfeiffer6 and Pfeiffer and ~aubmeyer' have established that the linear scaling constants of wustite formation at 1000°C in carbon-dioxide or low-pressure oxygen atmospheres

Jan 1, 1961

INTRODUCTION Within the past few years Clark (1972), King (1970), and King, et al. (1973), have summarized porphyry molybdenum occurrences. Clark (1972) includes as porphyry or stockwork deposits some occurrences more recent exploration has shown to be of other genetic types. King (1970) and King, et al. ( 1973) provide broad general descriptions that unfortunately are restricted to the US. Nor does the King, et al. (1973) description have benefit of the Wallace (1974), Hall, et al. (1974), or Giles (1975) data on alteration, fluid inclusions, or isotope chemistry. The synthesis presented here up- dates these older summaries, eliminating all but the well established porphyry molybdenum deposits as well as enumerating the unifying characteristics displayed by these deposits within the Cordillera of North America. This type of deposit occurs in the South American Andes as well, but Andean deposits are not well documented so only North American Cordilleran deposits are considered. Stockwork, porphyry, and Climax type molybdenum deposits are synonymous geo- logical labels for the large molybdenite de- posits found in parts of the western Cordillera of North America (Khruschov, 1959). These labels describe and define the type of deposit discussed herein. The term porphyry is preferred for this chapter because it describes the common characteristics; it separates the molybdenum deposits from the porphyry copper deposits, which have many similarities but also important differences. This usage also eliminates blanket application of the word stockwork to breccia pipe deposits such as Boss Mountain in British Columbia. J. R. Woodcock has contributed much to this chapter; his influence, original data, and thoughtful comments qualify him as co-author. Porphyry molybdenum deposits are characterized by fine-grained molybdenite occurring alone or with quartz and/or pyrite in fractures and open spaces of stockworks and breccias. The molybdenite is generally less than one millimeter across and in many cases too fine-grained to be seen with the aid of a hand lens. Occasionally some deposits con-

Jan 1, 1978

By John Chipman, Karl L. Fetters

Tax relationship between the composition of the slag and that of the underlying metal during the refining of a heat of liquid steel may best be studied in the light of the two broad physicochemical concepts of equilibrium and reaction rate. Actual steelmaking processes, typified by basic open-hearth practice, involve such complexities of operating variables that it is impossible to distinguish with any degree of certainty between the general limiting conditions imposed by chemical equilibrium and the effects associated with rates of diffusion or of chemical reaction. Further advances in the physical chemistry of steelmaking will depend upon our ability to distinguish clearly between these two kinds of effects, and the experimental work that must be done falls naturally into two classifications. The first is the study of chemical equilibrium that cannot be carried out with assurance under operating conditions but must be done in the laboratory. The second is the subject of rates of reaction and diffusion and the mechanism of the process as a whole, which can best be studied under operating conditions. The latter is not entirely independent of the former, since its interpretation often requires a knowledge of the equilibrium state. It is the purpose of this and of several papers that will follow to present the results of laboratory investigations of equilibria involving liquid steel and slag. Open-hearth slag is a complex mixture containing at least eight major components and perhaps twice as many whose influence may be classified as probably minor. It is not surprising that progress toward a complete understanding of such a material at high temperatures has been slow. Attempts to apply the established principles of physical chemistry to the behavior of the individual components of this mixture have been beset by an almost complete lack of data on its chemical properties in the liquid state. This has necessitated the adoption of various methods of approximation based upon such assumptions as, for example, that for a given component the ratio of its mol fraction in the slag to that in the metal is a constant, or that the molecular composition of the liquid slag is the same as its crystalline constitution after solidification. From the thermodynamic viewpoint, such assumptions are merely useful dodges, which enable one to hazard a guess as to the magnitude of the more fundamental quantities, the chemical potentials and activities of the components of slag. The problem of determining the activity of each substance in an eight-component system seems too complex to be undertaken without the aid of generalizations derived from experimental data on similar systems containing a smaller number of components. Accordingly, it was planned in the present investigation to study the equilibrium of molten iron with the simplest

Jan 1, 1941

By D. K. Crampton, H. l. Burghoff, J. T. Stacy

THE effect of cold-working upon electrical conductivity of copper and of copper alloys appears not to be generally known in detail Although several papers on the subject have been presented, showing variable effects according to alloy composition, it is often assumed that the 2 to 3 per cent lowering of the conductivity of ordinary tough-pitch copper by severe cold-working is typical for copper alloys Because of this situation it was decided to carry out the present work upon several types of copper, copper-zinc alloys over the commercial range of brasses, other binary alloys, and numerous age-hardening alloys in the quenched, and quenched and aged conditions The large number of alloys investigated made it impossible to study every one in the detail it may have merited Inasmuch as several interesting points that could not be satisfactorily explained came to light, further work is contemplated by the authors It is usually considered that the normal effect of cold-work on ductile metals and unordered alloys is to decrease conductivity slightly In alloys that are in the ordered state, as annealed or otherwise heat-treated, cold-working tends to disorder the structure, resulting in very marked lowering of conductivity The random state of atomic arrangement produces lower conductivity than the ordered state for the same composition 1 PREVIOUS WORK previous work in the authors' laboratory has shown the electrical conductivity of several copper alloys to be decreased by greater amounts than might have been expected, in view of the general knowledge on the subject, when cold-worked Guillet and Ballay2 investigated the influence of cold-work upon the resistivity of several metals and alloys, including copper and some copper alloys The increase of resistivity due to severe working was less than 4 per cent for all pure metals tested, while the increases for the alloys were generally higher In the copper-zinc alloys, they found that the increase of resistance due to drawing increased with zinc content, and reported a 21 7 per cent increase of resistance for an alloy containing 67 9 per cent Cu as severely worked Masima and Sachs3 studied the change in electrical resistance of three brass crystals when stretched in the tensile test, obtaining increases in resistance of the order of 3 per cent for 30 to 40 per cent reduction of area of the specimens The resistance decreased again when the cold-worked crystals were subsequently annealed Bardenheuer and Schmidt4 found that the conductivity of copper was decreased by 3 to 4 per cent when reduced 50 per cent by working The conductivity of 72-28

Jan 1, 1941

By Irving Lipkowitz

While the light metals are recognized generally as a distinct group in technical literature, economic classifications and data usually still treat them as part of the nonferrous group of metals. However, the economic characteristics of the light metals also differ markedly from those of other nonferrous metals. The distinctiveness of the light metals, as, a group and individually, becomes evident when their growth, since World War II is compared with that of other metals, as in Table 14.3.1. The growth of light-metals production has been much sharper than that of other metals. A weighted average for the light metals shows an increase of 112% during the 1958 to 1968 period. This compares with a 62% increase in the "All Primary Metals" component of the Federal Reserve Board Index of Industrial Production. The contrast was even sharper during the next six years (1968-1974), with light metals production up another 50% as against a 21 % increase in the FRB Primary Metals production index. The most important reason, however, for considering light metals separately is the trend and pace of technological change and not their distinctive statistics. Technology both creates and demands increasingly sophisticated materials. As technology advances and as all the world makes more extensive use of advanced technology, the importance of the light metals is likely to accelerate rapidly. There may be a profound clue to the future in the fact that light metals were predominant among the materials used in the construction of the Apollo 11 spacecraft. In determining what materials to use for the spacecraft and its equipment, the National Aeronautics and Space Administration (NASA) has explained that it did not look to "some of the more exotic metals" and relied instead on "generally proven materials." Accordingly, it apparently used a wide variety of metals, including precious metals, rare earths, special steels, copper, and light metals. What seems particularly significant is that, in seeking performance, NASA relied as heavily as it did on the light metals. Materials breakdown estimates show that aluminum accounted for over 75% of the materials used, titanium for another 5%, and magnesium was also used. Thus, light metals accounted for over 80%' of the materials used for the Apollo 11 spacecraft. The light metals are also unique in their availability. They rank high in abundance among the elements in the earth's crust. Aluminum is the third most abundant element, after oxygen and silicon, with magnesium ranking eighth, and titanium ninth. Among the structural metals, aluminum is the most abundant in the earth's crust, iron is second, magnesium third, and titanium fourth. This potential availability of light metals provides strong incentives for continuing improvements in process technology, because of two major national problems: (1) there is

Jan 1, 1976

By E. G. Woodruff

The earlier struggles in petroleum geology were directed to solving the Qrigin and method of accumulation of petroleum. We are now fairly well agreed on those subjects. Most of us think that the great mass of petroleum commercially produced comes from plants or animals, or possibly from both. We are confident that the oil was not produced where it is now found but has accumulated in reservoirs of various kinds. The types of reservoirs are certainly variable but they just .as certainly follow definite geologic laws. Some of these types of reservoirs can be determined from surface study; others cannot. We know, too, that these types of reservoirs (largely structures such as anticlines, domes, and terraces) are much more widespread than the oil pools. In other words, there are many places where good sands and good structures exist but where oil is not found. It is the purpose of this paper, therefore, to attempt to analyze, from a regional standpoint, some of the conditions that control the presence or absence of oil pools and to group them in a regional way, hence the term "Petroliferous Provinces." The paper lays no claim to presenting new facts but attempts to group and classify the information that so many have expressed again and again. The essential factors for an oil field are petroleum, a reservoir material, and conditions under which the petroleum can enter the reservoir but cannot escape except through the drill holes. The paper will first discuss the source of petroleum as it occurs in definite regions, then the regional arrangement of reservoir strata, and finally the areal arrangement of structures. To have petroleum, there must be a source. Since living matter is considered the source of the petroleum, geological conditions must have been such that living organisms were abundant. Arid regions on the earth's surface have not given rise to living things in sufficient abundance to produce oil; similarly, too cold regions and saline inland lakes. The converse of this is that warm moist conditions must prevail to produce an abundance of vegetable matter. Before an area can be

Jan 1, 1921

LANS are underway for the annual meeting of AIME, to be held in New York, February 17 to 21. The technical program includes meetings of all divisions of all three branches, Mining, Metals, and Petroleum. The bulk of the technical sessions will be held at the Statler Hotel, and the annual banquet will be held at the Waldorf-Astoria, Wednesday evening, February 20. The technical program of the Mining Branch activities is included in this issue. While it is not complete in every detail, it shows general interest groupings as well as subjects to be discussed. The program for each division is shown separately to facilitate following the activities of these special interest groups. Then, after a full scale and possibly somewhat strenuous technical meeting, a post-meeting feature will appeal to many of the members. A restful cruise to Bermuda and Nassau is offered at special rates to AIME members and friends. The schedule is a 3:00 pm departure from New York on the Queen of Bermuda on Saturday, February 23; arrival at Bermuda at 7:00 am Monday, February 25; arrival at Nassau at noon, Wednesday, February 27; and the trip ending again in New York at 9:00 am, Saturday, March 1. Rates begin at $202.10 per person, with higher rates depending upon accomodations desired. The base rate includes outside room with private bath and all meals, as well as Federal, Bermuda and Nassau taxes. Reservations for the trip should be made immediately through Leon V. Arnold, 36 Washington Square West, New York 11, who is in charge of arrangements.

Jan 1, 1952