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By A. G. McGregor

During the past 5 years, five new copper-smelting plants have been built and put into operation in the State of Arizona. The monthly copper output from these plants averages from 5,000,000 to 18,000,000 lb. Previously, there never was as much activity in copper-smelting plant construction in the same length of time in all the rest of the world. Naturally, in this amount of work, some new problems were met and new features in plant design and equipment developed. Some of these features are described in this paper. Concentrate Hauling, Unloading and Sampling System (a) Concentrate Car The International Smelting Co. has provided at its plant at Miami specially designed cars for hauling the concentrates from the mills of the Inspiration Copper Co. and the Miami Copper Co. The car has a bottom that is readily made tight to hold flotation concentrates and is quickly and cheaply unloaded. Figs. 1, 2 and 3 show views and details of the car. The main feature of this car is the slot in the bottom throughout its length, which is closed by means of short planks that overlap like ship-lap as shown by Fig. 1. At one end of the car an iron gate operated by a screw and hand wheel is provided, which clamps or presses the planks together, making the bottom tight. A removable tapered plug rests vertically over this gate when the loading of the concentrates at the mill commences. A concentrate unloading pocket (Fig. 4), 180 ft.long, is provided at the smelting plant, which has a conveyor belt running throughout its length underneath the track. To unload a car, the vertical plug at the end of the car is lifted by means of a chain hoist which is supported by a trolley overhead. The gate at the end of the car is opened approximately 18 in. The removal of the plug leaves a hole down through the concentrates. The concentrates are poked through the hole from the top of the car until it is convenient for a man to stand on the bottom and draw one of the slats in the bottom toward the gate end of the car. The concentrates are then raked down with hoes on their natural angle of repose,

Jan 1, 1917

By C. D. Demond

In reverberatory smelting, fuel is the chief item of expense, as it commonly is in processes using large percentages of it. Hence the most suitable supply is eagerly sought; that is, the supply which, in the end, yields the greatest net profit. The better grades are not infrequently bought, even at an advanced price, because they are apt to be decidedly more economical. High price, of itself, however, is no merit, for freight is generally the largest part of the cost of fuel, and the nearby supply may yield as high efficiency as that from a greater distance. If a poorer grade is reasonably good, and if its cost is low enough to more than offset the decreased technical efficiency, it is of course the more suitable. Any smelting operation depends for both efficiency and economy on raising the furnace atmosphere considerably above the "critical" temperature; that is, above the temperature at which smelting is completed. If this temperature is not exceeded, smelting stops, no matter how much coal is burned; and the real value of a fuel depends on the number of degrees that the temperature is continuously kept above this point. For example, if one fuel maintains 2,500" F. and another only 2,100 F., while the "critical" temperature is 2,000" F., the first is worth at least five times as much as the second, although the increase above atmospheric temperature is only one-fifth more in one case than in the other. This "margin of temperature" above the smelting point is much more significant than the total number of heat units developed from the fuel. The case is parallel to that of water flowing from a pipe. The reservoir may contain a billion gallons of water; but, even though the fluid has come to the nozzle, not a drop will run out, where it can be of practical use, unless the level in the reservoir is higher than the nozzle; and the speed and volume of flow depend on how much higher the level is in the reservoir than at this point. If the temperature in a furnace is not above the critical level there will be no slag to flow over the skimming plate, even though there are enough heat units to bring an unlimited quantity of charge up to the point of slag formation; and just as the value of a water supply for the purpose of putting out a fire depends largely on the effective head, so the difficulties of furnace management

Jan 1, 1915

By Harry L. Washburn, Robert L. Llewellyn, W. J. Halvorsen

Many of the problems that occur in the preparation plant originate from practices in the mine. Impurities in raw coal can be in the seam itself or from extraneous material taken in mining from the roof or bottom. In the case of underground mines, the choice of mining equipment will affect the size consist and the amount of extraneous material included with the coal. Also, governmental regulations concerning the degree of rock dusting, gobbing underground, and cleanup have increased the dirt in raw coal. Sulfur dioxide emission standards, on the other hand, are pressuring the coal industry to clean coal more thoroughly. Coal supplied for coking purposes is nearly all upgraded by washing, while for the largest market, electric power generation, a high proportion is shipped as a raw product with processing, in whole or in part, only necessary when excess impurities are mined with the coal. This chapter will deal primarily with plants that process or wash coal to some extent (Fig. 1) and only incidentally with mines shipping raw run-of-mine coal crushed to a top size of, usually, 51 to 102 mm (2 to 4 in.), with little, if any, other treatment. JUSTIFICATION FOR COAL PREPARATION During the past decade, major changes have occurred affecting the market, profit, and long-range planning of the coal industry. Mining companies have become "partners" with consumers at many new and some old mines, both for steam and metallurgical coals. Coal properties have become "assigned" tonnages at mutually agreed upon conditions and prices. Lower unit-train tariffs have been instrumental in helping coal markets to compete against oil and nuclear energy. Coal prices for power plants are still on a Btu (British thermal unit)

Jan 1, 1981

By S. Gstalder, J. Raynal

Consideration was given to simple tests which could be performed on rocks to give a measure of rock drillability. Various methods of breaking rocks were considered and the hardness test developed by Schreiner was selected for this study. The test involves application of an increasing load on the rock face through a flat-faced cylindrical punch until rupture occurs. Test results show that hardness is a good measure of the breaking strength of rocks. Useful relationships are shown to exist between hardness and other physical quantities such as specific disintegration, Young's modulus and sonic velocity. Specific disintegration (volume of rock broken per unit of work input) provides a possible means of comparing the effectiveness of other methods of rock breakage. The relationship between hardness and sonic velocity may be very significant for it may be possible to deduce rock drillability from sonic log data. provided that a mineralogical factor is taken into account. TO test further the results of the work, laboratory drilling tests were performed which closely simulated down-hole pressure conditions. Correlations of drilling results with rock hardness measurements were quite good. It was concluded that rock hardness, as measured in the laboratory or as deduced from sonic logs, could be used in relations for predicting rock drilling performance. INTRODUCTION Drillability of rocks cannot be defined in an absolute manner by a single quantity or measured by a single test. Resistance of rock to drilling depends to a large extent upon the means used for rock destruction. This complicates drillability classification of rocks for there may be as many classifications as there are methods of rock breakage without known functional relations between them. The objective of this work was to develop. in terms of rock destruction behavior, means of selecting the best drilling method for a given rock or the conditions for optimum output from a given drilling method. ANALYSIS OF ROCK DESTRUCTION TESTS Gauthier and Baron' have reviewed the many test methods which have been developed for determining the resistance of rocks to breakage. These include drilling tests, punch tests, scratch tests, resistance to shock, wear tests, etc. A standard drilling test might be to determine the time required to drill a standard depth (1/16 in.) in a rock using a bi-cone microbit (1 1/4-in. diameter) when a standard load (417 Ib) is applied at a standard speed of bit rotation (110 rpm). From the standpoint of similarity, the results of microbit drilling tests would seem to be most representative of the several methods suggested above. However, evaluation of drilling performance by this method is only qualitative and cannot be applied directly to actual drilling conditions. Punch tests basically measure rock hardness. Punches of various shapes and sizes, including small cones for Vickers' and Knoop's tests, the wedge for Epstein's test and the right circular cylinder for Schreiner's test, have been used. Results of these tests lead to a quantitative hardness classification which would seem to be related to the resistance of rock to bit-tooth penetration. Scratch tests are related to the resistance of rocks to abrasion such as would be encountered in drilling with diamonds. Either the width of the scratch obtained at a fixed load or the load required to give a scratch of a fixed width may be used to evaluate surface hardness of the rock. This should be related to the resistance of the rock to wear. The above tests, and probably many others. give relative measurements of the breakage or destruction characteristics of rocks. There is no direct relation between results of these tests and the drillability of rocks. Also, the tests each measure different quantities which have different dimensions and they do not permit direct comparison of numerical values. As one step in rectifying the above difficulties. it is proposed that the results of all test methods be expressed in terms of volume of rock destroyed per unit of work required; this is referred to as "specific disintegration". Test results may then be reported in a form which shows both a classification of rocks in regard to each method and a comparison of methods with regard to each rock. The disadvantage in using specific disintegration is the difficulty of measuring this quantity with accuracy. The volume of rock damage is difficult to measure. as is the true value of work input. Rock heterogeneity adds to the

Jan 1, 1967

By Hiroshi Kato, Shin’ichi Nagashima, Hiroshi Takechi

The preferred orientations detleloped during cold rolling, annealing, and hot rolling of low-carbon steel sheets have been investigated by means of an inverse pole figure technique. And X-ray line profile meas-urerrlents were made for the study of the factor which causes the textural changes between cold-rolled and recrystallized sheets. From ND (sheet normal divection) and RD (rolling direction) inverse Pole figures tlze axis detisity change with increasing cold reduction was measured and the Preferred orientations were analyzed. These results can be explained by crystal rotation due to slip during rolling deformation. The ND axis density change during annealing of cold-rollitig sheets is contrary to the change observed in the case of rolling. It was found that the orientation dependency of stored strain energy resulting from cold rolling apparently corresponds to the textural changes during recrystallization. The texture in hot-rolled sheets was found to be influenced by finishing tenlperatltre. In a sheet kol-rolled below the Ar, temperature a significant differernce in texture between the surface and central layers was obtained, the former having {hkl}(111} and {110 )(uvw) orientations and the latter having {pqr}( 110) orientation. A large number of investigations1 6 have been made on the textures of iron and low-carbon steel sheets, and, since it was shown7 13 that preferred orientations are closely related to deep drawability of steel sheets, studies14" 7 on the influence of production processes upon textures have been made from the standpoint of industrial interest. Generally, the textures in low-carbon steel sheets have several components of preferred orientations, but the overlapping of poles makes it difficult to analyze texture quantitatively from pole figures. On the other hand, an inverse pole figure directly expresses quantitative values of components of preferred orientations as the density of a certain sample axis with respect to the crystallite coordinates. Such a texture representation is desirable for a study of deep drawability. The purpose of the present work is to use both inverse and conventional pole figures, with emphasis on the former, to clar~fy the textural changes ~n low-carbon steel sheets by the production processes of hot rolling, cold rolling, and annealing. And the factor causing the textural changes during annealing is studied using an X-ray diffraction line profile technique. EXPERIMENTAL PROCEDURE Sheet specimens for study of cold rolling and annealing textures were taken from a hot-rolled strip of rimmed steel 2.7 mm thick. The chemical composition is shown in Table I. Although the study of cold-rolling textures requires a suitable material with random orientation, it is difficult to produce a perfect random one. But the used specimens, obtained from the hot-rolled strip with a finishing temperature higher than Ar3, were nearly random, such as shown in Fig. 15. These were cold-rolled to various reductions by a 4-high rolling mill with 150-mm-diam work rolls and 300-mm-diam backup rolls. The influence of hot-rolling conditions such as finishing and coiling temperatures on textures of hot-rolled strips was studied. The chemical compositions of these hot coils are given in Table I1 and the hot-rolling conditions are given in Table 111. inverse Pole ~i~ure -~easurement. Two methods for determining inverse pole figures with high precision have been proposed. The first, by Jetter et a1.,18 consists of obtaining mean densities of divided regions in a unit stereographic triangle by solving simultaneous linear equations to approximate the integral relation between conventional and inverse pole figures. The second, proposed by ~oe'~-'~ and Bunge,22'23 consists of determining an expanded series of spherical surface harmonics which express axis densities from several sets of pole distribution data. Both methods require laborious numerical calculations which make them unsuitable for practical use. However, the axis densities of the locations corresponding to low Miller indices in a unit stereographic triangle can be obtained

Jan 1, 1969

By R. V. Higgins

This paper presents a computer method to obtain the shape factors and equal cell volumes of the channels for any well spacing pattern from a potentiometric model. By using this program the authors have processed the data for the seven-spot, direct line-drive and the staggered line-drive patterns. The data for the five-spot pattern had been previously processed by a noncomputer method and are included for completeness. The shape factors and volumes for the channels are presented in tables for those who want to use them to process data using their own permeability relationships and viscosities of their reservoir oils. The authors have used the data and sets of representative permeability curves to process sample calculationr of waterflood performances. The comparison of the calculated results shows that the influence of well spacing is small. The permeabilities of the reservoir rock to oil and water had a greater influence on oil recovery for a given pore-volume throughput of water than the well spacing pattern. The more water-wet the reservoir rock, the better the possibility of permeabilities which are conducive to good recovery. The viscosity of the reservoir oil also influences the recovery more than the well spacing pattern. The reduction in the percentage recovery of oil with increase in viscosity of the reservoir oils is small when oil viscosities are in the range of 0.1 to 3. Above this range the reductions in recoveries are extensive. Sample comparisons of the time required for different patterns to recover the oil are presented. Results of an example calculation are given to show the effect of the permeability profile on recovery. INTRODUCTION The effect of well spacing pattern on the recovery of oil when flooding with either gas or water has been studied by many investigators. Muskat et al.1 presented an analysis using conductivity, sweep efficiency and unit mobility to the time of breakthrough. Dyes et al.2 used experimental techniques (X-ray shadowgraphs) and different mobility ratios. They presented quantitatively the relationship between mobility and sweep efficiency at and after breakthrough. Hauber3 presented a method to predict waterflood performance for arbitrary well spacing patterns and mobility ratios. Craig et al.,4 using techniques similar to Dyes et al. to determine sweep efficiency for a five-spot pattern, added the use of relative permeability curves at breakthrough and thereafter. Douglas et al.5 sed rela- tive permeabilities and continuously changing saturations throughout the entire five-spot flood pattern. In obtaining their solutions they used finite-difierence equations. Hig-gins and Leighton6,7 also used relative permeabilities and continuously changing saturations throughout the pattern before and after breakthrough. They employed techniques that process a flood-pattern calculation on the computer in about one minute. The methods of Douglas et al. and Higgins and Leighton both checked closely the laboratory results for a wide range of mobility ratios. This paper presents some sample performances calculated by the Higgins and Leighton method that show the effect on recovery of different permeabilities and viscosities using the seven-spot, the line-drive and the staggered line-drive, as well as the fivespot flood pattern. No previous paper has presented these data using different permeability curves and continuously changing saturations throughout the flood patterns. The paper also presents (1) the results and analyses of the flood-pattern prediction, (2) the computer techniques for determining the shape factors and volumes from the potentiometric models for the foregoing flood patterns, and (3) the shape factors and volumes of the channels of the flood pattern in the event reservoir engineers may like to process waterflood calculations using their own permeability curves and reservoir oils. DESCRIPTION OF METHOD VOLUMES AND SHAPE FACTORS The use of channels taken from a potentiometric model (see Fig. 1) to aid in calculating the performances of water floods of nonlinear patterns has been thoroughly explained in the literature.0,7 Therefore, very little theory, discussion, or proof regarding this phase will be repeated in this paper. The computer method presented in this paper to calculate the volumes and the shape factors of the channels of potentiometric models employs the trapezoidal rule for the volumes and the Pythagorean theorem (the hypotenuse equals the square root of the sum of the squares of the two sides of a right triangle) for the shape factors. In calculating the volume of a channel, the area of each cell in the channel is determined and then multiplied by the thickness to obtain the volume. In determining the areas of the cells, trapezoids are constructed whose vertical sides are spaced Ax apart, as shown in Fig. 2. The length of the sides is the difference between an ordinate cut off by the top and bottom of the cell — usually equipo-tentials. The coordinates of the points along an equipo-tential or streamline are obtained by Lagrange's8 equation of interpolation for which the constants are coordinate points at the intersections. Three intersections for con-

Jan 1, 1965

By W. N. Lacey, B. H. Sage

THE results of an extensive experimental program relating to the effectiveness of gravel screens have been correlated. The factors considered in some detail include gravel size and condition of packing, sand size and size distribution, fluid velocity, fluid viscosity, and thickness and arrangement of gravel screens. Good agreement between calculated values based upon probability considerations and experimental results relating to the influence of the thickness of the gravel screen was obtained. All of these factors are treated in the correlation in order that their influence may be taken into account in ascertaining the characteristics of an effective gravel screen for a particular set of conditions. The details of the experimental program are not given in the present paper but a description of generalized behavior and typical experimental results are recorded in graphic form. INTRODUCTION Gravel screens have been placed in water and oil wells for a number of years1,2,3 with the dual objective of increasing the productivity and decreasing the entrance of sand into the well bore. An understanding of the factors controlling the effectiveness of gravel screens in this connection is of industrial interest because it will lead to the proper selection of gravel. Some of the fundamental considerations involved in the migration of sand through a coarser body of porous materials were investigated by Coberly and Wagner4 and further experimental work has been carried out by Gumpertz.5 Apparently the pertinent phenomena are somewhat complex and are influenced by many variables. The present paper deals with the prediction of the behavior of gravel screens under the conditions encountered in practice but does not attempt to discuss the experimental methods or results that were obtained as a background and upon which the prediction is based. INFLUENCE OF GRAVEL SCREENS UPON PRODUCTIVITY The use of a gravel screen may increase the productivity of a well by increasing its effective diameter, and this constitutes one of the objectives of its use. The permeability of most gravels and coarse sands that are employed in practice is so large compared to that of the sand in place that relatively little loss in production rate will arise from the use of material fine enough to cause the desired resistance to sand migration. For example, in Fig. I is depicted the approximate variation in the permeability of closely sized spherical gravels under the conditions of packing likely to be encountered in screens. The dotted lines indicate the variation that might be found because of differences in packing. It should be realized that the permeability is not a single-valued function of the. average grain diameter but is related to a large number of factors, including the size, the size distribution and the shapes of the particles. However, Fig. I does permit a rough estimation of the permeability of closely sized- spherical gravels and shows that the permeability with even the smaller particles is very large compared to that of most petroleum production horizons.

Jan 1, 1941

By J. B. Austin

IN considering so complex a process as the smelting of iron in the blast furnace, there is obviously no single method of calculating efficiency that gives a complete appraisal of the performance of the furnace in all its several functions; such a comprehensive view as is required to evaluate producing ability and manufacturing costs for a given furnace is obtained only by considering a group of efficiencies, each of which measures the performance of the furnace from a specific point of view. For instance, there is the rate of consumption of coke per ton of iron produced, which is probably the most frequently considered, and is certainly one of the most important of the group; there is the efficiency of recovery of iron charged; and there is the efficiency of utilization of energy, both chemical and thermal, in some respects related to the former two yet in other ways independent of either. In each of these cases, the calculation can be made on the basis of the actual input of material or energy, or it may be based . upon a comparison with the minimum amount of material or energy that would be required by a "perfect" furnace; that is, an imaginary ideal furnace analogous to the perfect steam engine used in thermodynamic calculations, when this furnace is operating under optimum conditions. Moreover, the furnace itself can be considered either as an apparatus for smelting iron or, taking a somewhat less common point of view, as a gas producer yielding iron and slag as by-products. Some of these effi-ciencies are more useful than others, yet all are instructive; for a knowl-edge of them not only leads to good engineering practice from the standpoint of control but also discloses limits to possible improvement in performance and indicates the lines along which improvement is most likely to be profitable. Estimates of some of these efficiencies have appeared from time to time in the literature, but many of them are open to objection because they are based on data of uncertain accuracy or because they have been calculated without due regard to the thermo-dynamic principles involved. Moreover, so far as the author is aware, no general survey of the blast furnace comparing its performance in all the aspects mentioned has been made.

Jan 1, 1938

By J. Szekely, V. Stanek

Heat and gas flow interactions in nonisothermal packed beds were examined in the paper. A study was made of the response of the system to a step or pulse change in the inlet gas temperature, with a fixed value of the overall pressure drop across the bed. Under these conditions the heat flow and fluid flow transients are coupled because the convective heat transfer rate is alfected by the mass flow rate of the gas which, in turn, for a fixed pressure drop will depend on the temperature profile in the system. The Problem was stated in terms of differential equations, which were integrated numerically. The parameters used in the computation were so chosen to reflect the operation of the stack region of blast furnaces and sinterbeds. The computed results showed that the pressure drop-flou1 relationships and the rate of progress of the temperature fronts (waves) were strongly interrelated and were also markedly affected by variations in particle size and in void fraction. MANY metallurgical processes involve the contact of solid particles with a gas stream in a packed bed arrangement under nonisothermal conditions. Examples are shaft furnaces, regenerators, pebble heaters, and the sinter process. Although the heat and mass transfer aspects of packed bed processing have been extensively studied, the associated flow phenomena and in particular the effects of nonisothermality on the flow, have received little attention to date. :In fact, most of the previous workers considered the flow rate of the carrier gas time invariant and independent of the heat or mass transfer processSzekely and carr2 have shown that the pressure drop-flow relationships in nonisothermal packed beds may be strongly affected by the temperature profile within the system. These authors have devised a method for relating the pressure drop to flow for a given temperature profile. thus providing an extension of the Ergun equation to steady nonisothermal systems. Finally, in a recent paper willmot3 examined the response of regenerators to externally imposed changes in the gas flow rate. Both these investigations were somewhat specialized since, in general, neither the temperature distribution nor the gas flow rate may be regarded as truly independent variables, thus the heat transfer and the fluid flow problems have to be solved simultaneously. The work reported here is divided into two parts: in Part 1 the general formulation is given and a detailed discussion is presented of fixed bed systems. Part is devoted to systems in which a gas and particulate solids are contacted in a counter flow arrangement. FORMULATION Consider a nonisothermal fixed packed bed, extending from through which a gas is flowing. The problem is to develop a relationship between pressure drop and gas flow (with the gas flow being the dependent variable) and to evaluate the rate at which a change in the gas temperature, imposed at the inlet, travels through the system. Let us consider an infinitesimal section of the bed and establish differential heat, mass, and mechanical energy balances over this region. In addition, relationships are needed describing the temperature dependence of gas density (equation of state) and the temperature dependence of viscosity. These may be written as: where c, and are constants. It is noted that in this formulation we neglected any temperature gradients within the solid particles, thus assuming these to be either sufficiently small or of sufficiently high thermal conductivity to meet this condition. The justification and consequences of this assumption will be mentioned in the discussion.

Jan 1, 1970

By O. D. Gonzalez, H. A. Wriedt

Alloys ranging from pure iron to pure nickel were saturated with nitrogen gas at 918°, 999°, and 1217°C and analyzed. The solubility of nitrogen at 1-atm pressure was obtained as a function of nickel content for the whole range of iron-nickel alloys and the temperature dependence of solubility is shown for the experimental alloy compositions. The heat of solution and the entropy of solution of nitrogen in the alloys as func-tiom of composition up to 41 pct Ni are given. 1 HE acquisition of more exact thermodynamic information for systems composed of iron with various alloying elements continues to interest ferrous metallurgists. The interstitial alloying elements, especially carbon, hydrogen, and nitrogen, comprise a field of particularly intense study. A recent investigation of carbon solubility in Fe-Ni alloys held at 1000°C in gases of fixed carbon activity showed an unpredicted minimum in the solubility near 72 pct Ni.1 The present investigation was undertaken to see if a similar anomaly in solubility existed for nitrogen in Fe-Ni alloys. The solubility of nitrogen in ? iron at known nitrogen activities has been measured several times.&apos;-&apos; Corresponding information for the solubility of nitrogen in solid Ni and Fe-Ni alloys is not available. Juza and sachsze9 reported that metallic nickel dissolved 0.07 pct N in equilibrium with Ni3N at 445°C. This result was regarded as dubious by Turkdogan and Ignatowicz10 who found less than 0.0004 pct N in nickel specimens equilibrated at 600°C with ammonia-hydrogen mixtures having fugacities of N2 gas up to 35,000 atm. Such fragmentary reports indicate only that nitrogen gas has a very much lower solubility in nickel than in iron. MATERIALS A purified iron from Battelle Memorial Institute was used for solubility measurements. This grade contained more than 99.95 pct Fe, the highest content of any measured individual impurity being 50 ppm for each of As, C, Cu, and Pb. The nickel and iron-nickel alloys, supplied by the International Nickel Co., contained 0.02 to 0.04 pct C, 0.17 to 0.19 pct Mn, 0.04 to 0.08 pct Si, < 0.01 pct P, <0.03 pct S, and <0.20 pct Co as principal impurities. The Fe-0.59 pct Mn alloy was of zone-melted quality, the highest concentration of any individual impurity being 15 ppm Al. The "prepurified" grade of nitrogen gas from Matheson Co. had a nominal nitrogen content of 99.996 pct. An "electrolytic" grade of hydrogen gas from National Cylinder Gas. CO. in which the principal impurity is water vapor was admixed with the nitrogen to prevent oxidation of these specimens. This grade was preferred to a purer grade because the presence of some oxygen helps in suppressing contamination of the specimens, for instance, by silicon from the porcelain furnace tube. EXPERIMENTAL PROCEDURE The specimens were equilibrated in vertical tube furnaces through which a 99 pct N2-1 pct H2 gas was passed at ambient pressure. For the 915", 918", and 999°C runs, a wound-resistance furnace was used, and for the 1217°C runs, a furnace with a tubular silicon carbide element was used. The temperature control system on both furnaces was similar: a Weston "Celectray" controller with a modulator, responding to the electromotive force of a thermocouple with its hot junction in the furnace, switched the furnace current between high and low settings. The temperature distributions in the working zones of the furnaces were determined with calibrated Pt/Pt-10 pct Rh thermocouples. The overall uncertainty in temperature was estimated to be ±3° at 915° to 999°C and ±5° at 1217°C . Consideration of the small temperature coefficients of the equilibria studied, together with the error limits in the method of analyzing for nitrogen, showed that further refinement in temperature uniformity would give no improvement in resultant accuracy. The reactive gas was generated by mixing together "prepurified" nitrogen and "electrolytic" hydrogen directly from cylinders commercially supplied. The flow rates of nitrogen and of hydrogen were fixed by setting with bleeders the pressure drops across the individual calibrated flow meters of constant resistance. For any given alloy, the solubility of nitrogen at 1-atm pressure (% N) was obtained from the analyzed nitrogen content of equilibrated specimens (% Na)according to Sieverts&apos; law, thus

Jan 1, 1962

By M. Lastra, A. Cruz, J. Menacho

The technical feasibility of treating exotic copper ore with an acid cure using concentrated H2S04 is studied. Applications in a conventional percolation leaching circuit for unaltered ore and in a conventional agitation leaching circuit for altered ore are examined. The main effects of an acid cure are to inhibit silica dissolution and to increase the sedimentation rate of agitated pulps. An increase in the rate and degree of copper extraction is also observed. Based on these results and the minimal additional investment required, acid curing appears to provide an excellent approach for treating exotic copper ores.

Jan 1, 1980

By R. H. Harrington

THE definition of precipitation-hardening is well understood and its principles have been subjected to study for some time. However, the variation of properties with double aging, combined with strain-hardening, gives promise of new and useful phenomena. Properly to understand these distinctions, definitions of these terms are necessary. Precipitation-hardening. This reaction usually depends upon an alloy having such a composition that it consists only, or in major part, of but one phase, a solid solution, at a high temperature, so that, upon slow cooling, this solution breaks down into two phases, the solid solution and a compound. By heating the alloy to the temperature for maximum solution of the compound, quenching, and reheating to a suitable lower temperature for critical dispersion precipitation of the compound, useful properties of the alloy may be developed to a maximum. Double Aging.-Dougle aging in part is similar to the process for precipitation-hardening, consisting of heating a precipitation-hardening alloy to the solution temperature, quenching, reheating to the suitable dispersion precipitation temperature, strain-hardening, and again reheat-ing to a suitable temperature to develop certain useful properties to a maximum. The strain-hardening may be induced by two methods: (1) a rate of cooling from the first reheat may suffice to strain the solid solution lattice of the alloy; or (2) the alloy may be cold-worked to a suitable degree between the two reheats.

Jan 1, 1936

By Jack White

W. I. Garms-—The authors state that when they added 11 tons of balls to the 45 pct volume ball load, the power needle did not budge. The question arises as to whether any increase in capacity accompanied the 11-ton addition. It is hardly conceivable that all of the balls making up the l l-ton addition were sterile. However, as the work done in the ball mill is not by kilo-watthours per se or balls per se but by kilowatthour-balls, it is possible that the kilowatthourballs in the mill before the ll-ton addition had a different amperage, voltage or robustage than those in the mill after the addition and that the overall outcome was that equal work was done before and after the addition. The authors can keep the efficiency that they got with the 45 pct volume 1-in. ball charge and get additional capacity by putting more kilowatthourballs to work in the form of the addition of 11 tons of 2-in. balls to the present ball charge, and subsequent makeup additions by weight of 20 pct 2-in. balls and 80 pct 1-in. balls. J. F. Myers (authors&apos; reply)-—Mr. Garms points his finger at the 11 tons of "sterile" balls added to the Tri-cone mill. A fact so interesting to us that we felt it should be reported. Clearly, ball slippage at the existing mill speed prevented any further transfer of power from the shell to the ball mass. We agree that the kilowatthourballs would increase, were we charging rough 2-in. balls as suggested by Mr. Garms. The assumption is, of course, that we would get a corresponding increase in work done. Our reported data (CIME meeting, Vancouver, 1946) shows a gain of work accomplished of 7.6 pct as we decreased the ball size from 2 in. to 1% in. and a further gain of work accomplished of 2.1 pct when we went from 1 % in. to 1 in. The small ball results reported by H. R. Banks at Chapman Camp are also very convincing. In the case of 2-in. balls they would take the conventional ball path and start cascading. They would thus destroy the classifying pool over the "foot" of the

Jan 1, 1951

By Jack White

W. I. Garms-—The authors state that when they added 11 tons of balls to the 45 pct volume ball load, the power needle did not budge. The question arises as to whether any increase in capacity accompanied the 11-ton addition. It is hardly conceivable that all of the balls making up the l l-ton addition were sterile. However, as the work done in the ball mill is not by kilo-watthours per se or balls per se but by kilowatthour-balls, it is possible that the kilowatthourballs in the mill before the ll-ton addition had a different amperage, voltage or robustage than those in the mill after the addition and that the overall outcome was that equal work was done before and after the addition. The authors can keep the efficiency that they got with the 45 pct volume 1-in. ball charge and get additional capacity by putting more kilowatthourballs to work in the form of the addition of 11 tons of 2-in. balls to the present ball charge, and subsequent makeup additions by weight of 20 pct 2-in. balls and 80 pct 1-in. balls. J. F. Myers (authors&apos; reply)-—Mr. Garms points his finger at the 11 tons of "sterile" balls added to the Tri-cone mill. A fact so interesting to us that we felt it should be reported. Clearly, ball slippage at the existing mill speed prevented any further transfer of power from the shell to the ball mass. We agree that the kilowatthourballs would increase, were we charging rough 2-in. balls as suggested by Mr. Garms. The assumption is, of course, that we would get a corresponding increase in work done. Our reported data (CIME meeting, Vancouver, 1946) shows a gain of work accomplished of 7.6 pct as we decreased the ball size from 2 in. to 1% in. and a further gain of work accomplished of 2.1 pct when we went from 1 % in. to 1 in. The small ball results reported by H. R. Banks at Chapman Camp are also very convincing. In the case of 2-in. balls they would take the conventional ball path and start cascading. They would thus destroy the classifying pool over the "foot" of the

Jan 1, 1951

By B. C. Allen

Liquid surface tensions of copper and 18 Group IV-A to VIII transition metals (Ti, Zr, Hf, V, Cb, Ta, Mo, W, Re, Ru, Rh, Pd, Os, Ir, Pt, Fe, Ni. Co) have been measured by the static pendant-drop and dynamic drop-weight methods on the same rod sample. The drops were formed by electron-bombardment heating in high vacuum. Application of necessary corrections enabled determination of surface tensions to k2 pct and agreement between methods to * 1 to 4 pct for all the metals studied. Evidence is presented that the liquid surface was well screened by metal vapor, suggesting negligible adsorption of gaseous impurities and that the surface tensions measured are characteristic of the metals involved. Correlations between liquid surface tension and melting point, molar volume, heat of vaporization, and atomic number are presented and discussed. Temperature coefficients of surface tension were calculated using Eötvös&apos; law. SURFACE tension and interface energies of metals are the result of incomplete atomic coordination resulting in a force perpendicular to the boundary, tending to minimize its area. These energies are important in many phases of metallurgy, including microstructure, sintering, joining, electronic emission, and lubrication, which in turn affect many physical and mechanical properties of metals. Liquid surface tension refers to the interface between the liquid and its own vapor or nonreactive atmosphere, and is considered a physical property of the liquid. Since equilibrium shapes can be readily obtained with liquids, the units of surface tension (force per length) and interface energy (energy per area) are interchangeable. Thermo-dynamically, the surface tension ?LV is given by the change in free energy F with surface area A at constant pressure P, temperature T, and composition N: for commercially important refractory metals, vanadium, columbium, tantalum,13,14 molybdenum,14 and tungsten,l5 and none for the rare platinum-group metals and rhenium. Measuring the surface tensions of transition metals is difficult because of their high reactivity and melting points. Of the many techniques available,16-18 the pendant-drop 19-21 and drop-weight methods17,22 are considered superior because they can be modified to eliminate persistent sources of contamination such as supports and capillaries necessary in the popular sessile drop, capillary rise, and maximum-bubble-pressure techniques. The necessary modification is to melt a drop on the tip of a vertical rod, which provides support through a solid of the same composition.13,15 The object of the work was to study the surface-tension behavior of copper and transition metals, having reasonably low vapor pressures. Liquid surface tension of each pure metal was systematically determined by using a combination of the static pendant-drop and dynamic drop-weight methods on the same rod. Liquid drops were formed by electron-bombardment heating in high vacuum. EXPERIMENTAL WORK As indicated in Table I, the metals studied were high purity and generally were obtained in rod form. The exceptions were titanium and zirconium, which were machined from crystal bars, and molybdenum (tot 11, osmium, and ruthenium, which were sintered and arc cast into rods. All the metals were ground or swaged to desired sizes between 1- and 7-mm diam, and centerless ground round and smooth to a finish better than 50 µ in., rms. Each rod was thoroughly cleaned with steel wool, degreased, acid etched, and dried. In a typical run, the rod was vertically clamped in a modified floating-zone electron-bombardment furnace designed after Calverley23 and Carlson.24 The specimen was outgassed and maintained positive at several kilovolts in a dynamic vacuum of 10-5 to 10-7 mm. The bottom end was enclosed by a tantalum pillbox and heated by electrons emitted from a hot concentric tungsten filament mounted on a movable bracket. The bombardment power was slowly raised until melting was observed. Power requirements ranged from 30 w for copper to 1300 w for 4-mm tungsten. The stabilized and out-gassed drop of near-maximum size was photographed at 4. 1X on panchromatic film at desired time inter-

Jan 1, 1963

By T. A. Wright

THE SAMPLING of waste materials containing copper, lead and tin has taken on a new significance within recent years, and is of increasing importance, on account of the entry of some of the copper refineries into this field and the tendency towards consolidations among the smelters. In the past, such material was sold on the basis either of a rough or grab sample or of casual inspection of the lot. The two principal sources of this waste are the processes of fabrication and the scrapping of automobile, electrical, plumbing, railroad and other equipment. In both cases much material can be sorted, salvaged and sold by classification and grade to be melted "as is" or with the addition of new or virgin metal. The increasing care in classifying exercised in the large manufacturing plants tends to increase the proportion of this usable scrap; on the contrary, the increasing use of more complex and special non-ferrous alloys tends to make sorting and grading more difficult in turnings, borings, clippings, etc., and consequently is making sampling of more moment. In tin, lead, aluminum, and zinc furnace by-products such as ashes, drosses, skimmings, etc., the trade practice of evaluation has not varied much. For instance, tin drosses, battery lead, and aluminum skimmings are ordinarily sold on what is called "metallic button" or "metallic recovery" or "metallic yield." Copper and lead waste, however, is being sold more and more on actual copper and lead contents based on sample and chemical analyses. This paper will be devoted chiefly to the sampling of materials suitable only for refining and recovery of one or more of the metals present. The methods described are often based on the fact that but one metal, such as copper, is to be paid for. The loss of volatile constituents in melting does not appreciably affect the final copper result, as the "after-melting" assay can he readily calculated to the "before-melting" basis, but if smelter efficiency continues to increase, so that in time zinc, for instance, may be recovered on a paying basis, the method of sampling dirty brass, for example, will have to be changed also. As a matter of fact, we may expect that improved refining processes will make possible the partial recovery of lead and tin which are now lost.

Jan 1, 1928

By P. S. Rudman

The solubility limit and the diffusivity of carbon in molybdenum have been obtained by duffising carbon into molybdenum rods from a Mo + Mo2C powder mixture. The solubility limit was taken as the long-time asymptotic limit of the rod composition. The diffusiv-ity was obtained from fractionally saturated rods from the rate of change of the average composition. Compositions were determined by chemical analysis. The solubility limit obtained is: WhILE the Mo-C system is important in refractory alloy technology neither the solubility limit nor the diffusivity of carbon in molybdenum is unambiguously known. In Fig. 1 the Mo-C phase diagram is presented. The heavy lines, the terminal solution solubility limit, and the eutectic temperature are results of the present investigation and will be discussed in detail later. However, it is readily seen that the previously published solubility limit determinations, Few and Manning1 and Fromm and ROy2 differ by up to an order of magnitude. The general form of Fig. 1, the Mo2C field, and a eu- tectic temperature -2200°C are due to an early Investigation by Sykes et a1.3 Although they did not determine the solubility limit, they did establish that the maximum at the eutectic temperature was about 1000 ppm. The only other prior data found on the solubility limit is from a lattice-parameter study by Speiser et a1 .,4 from which it can be concluded that the maximum solubility is greater than 1800 ppm. There does not appear to be any data oh the diffusivity of carbon in molybdenum. However, Samsonov and Epik5 have determined, from the rate of growth of an MozC layer, the diffusivity of carbon in Mo2C, and this has been erroneously interpreted, for example by ~c~eil,&apos; as applicable to diffusion of carbon in molybdenum.

Jan 1, 1968

By L.W. Eastwood, Arthur E. Bousu, C. T. Eddy

The recrystallization and grain-growth phenomena of cold-worked metals have considerable industrial importance because of their role in the fabrication of metals. For this reason, and because of the general academic interest in the subject, these processes have received considerable attention since the time of J. E. Stead&apos;s paper1 on The Crystalline Structure of Iron and Steel. There are considerable differences of opinion regarding the theory of recrystallization and grain growth and also differences in the observation of the modus operandi of the processes themselves. The value of many of the existing quantitative data on grain growth is decreased by the failure to distinguish between the grain sizes just after complete recrystallization and those resulting from coalescence. For this reason also, the value of the diagrams of stable grain sizes, like those produced by Bass and Glocker2 and Czochralski3, is lessened in so far as an interpretation of the facts of recrystallization is concerned. It is hoped that the data presentcd in this paper will help to clarify and to simplify the facts relating to recrystallization, and at the same time will show that some of the present-day conceptions are untenable. A paper on the theory of recrystallization, with additional data, will be completed in the near future by the writers. Since the literature on the subject has been adequately and frequently reviewed, the only referenccs to it in this paper will be those necessary in the discussion of the data presented.

Jan 1, 1935

By Arthur E. Bousu, C. T. Eddy, L. W. Eastwood

The recrystallization and grain-growth phenomena of cold-worked metals have considerable industrial importance because of their role in the fabrication of metals. For this reason, and because of the general academic interest in the subject, these processes have received considerable attention since the time of J. E. Stead&apos;s paper1 on The Crystalline Structure of Iron and Steel. There are considerable differences of opinion regarding the theory of recrystallization and grain growth and also differences in the observation of the modus operandi of the processes themselves. The value of many of the existing quantitative data on grain growth is decreased by the failure to distinguish between the grain sizes just after complete recrystallization and those resulting from coalescence. For this reason also, the value of the diagrams of stable grain sizes, like those produced by Bass and Glocker2 and Czochralski3, is lessened in so far as an interpretation of the facts of recrystallization is concerned. It is hoped that the data presentcd in this paper will help to clarify and to simplify the facts relating to recrystallization, and at the same time will show that some of the present-day conceptions are untenable. A paper on the theory of recrystallization, with additional data, will be completed in the near future by the writers. Since the literature on the subject has been adequately and frequently reviewed, the only referenccs to it in this paper will be those necessary in the discussion of the data presented.

Jan 1, 1935

By Y. G. Shiau, J. E. Burke

Several attempts have been made to account for the fact that grains in a fully recrystallized metal will coarsen on annealmg. Two fundamentally different hypotheses have been advanced, with several variations of each. One school considers that the cause of grain growth is the surface energy of the grain boundary. The theory of Jeffriesl that grain size and grain size contrast control growth is an example. The second school considers the primary cause to be a difference in the lattice energy on either side of the grain boundary. The more perfect grains are considered to grow at the expense of their less perfect neighbors, with a decrease in free energy, and a consequent increase in the stability of the system. Burgers2 presents the case for the strain or lattice imperfection theory of grain growth quite completely. The latter theory is attractive, since there is no doubt that differences in lattice energy or lattice perfection can cause grain boundary migration. A recrystallization nucleus grows for this reason as was beautifully demonstrated by van Arkel and Ploos van Amstel.³ Although it is generally stated that grain growth does not precede recrystallization, several workers4-5 have shown that small strains may induce a single crystal in an aggregate to grow, or at least may cause some grain boundary migration. The origin and nature of the imperfections that are considered to be responsible for normal grain growth have never been clearly described, but it is generally agreed that they are a consequence of the difficulty of atomic reorientation in the solid state, and that they do not seriously differ from the type of imperfection that can be introduced by mechanical deformation. An object of the present work was to determine whether the introduction of mechanical deformation would cause grain growth in a specimen which would not otherwise show it under the conditions used. It was also planned to determine the effect of such deformation on the rate of growth in a specimen which would show growth in the unstrained condition. Recently Maddigan and Blank6 have indicated that slightly strained specimens of alpha brass can undergo considerable growth prior to recrystallization if annealed at low temperatures. French7 has reported that at deformations less than 17 pet it is very difficult to detect the beginning of recrystallization in the same material. It was therefore planned to broaden this work to include a complete study of the microscopic behavior of alpha brass under condition~ of temperature, time, grain size and deformation such that recrystallization would not occur or would occur to only a Small extent. Experimental Procedure The brass was prepared by melting cathode copper and commercially pure zinc

Jan 1, 1949