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By J. H. Yang, K. E. Gray

Results of single-blow bit-tooth impact tests on saturated rocks under elevated confining pressures and zero pore pressure were reported in a previous publication.1 This paper presents an extension of the earlier work to include a study of crater formation during tooth impact on both gas- and liquid-saturated Berea and Bandera sandstones at elevated confining and pore pressures. The basic data obtained were force-time, displacement-time, velocity-time and force-displacement curves during crater formation. Crater volume was also measured and the mode of crater formation determined. Bit tooth geometry, depth of penetration and velocity of impact were held constant. Results indicate that, with pore fluid present in the rock, failure trends from brittle to ductile as pore pressure is increased at constant confining pressure (pore pressure and borehole pressure were equal) For a given rock type, the mode of crater formation was dependent not only upon the nominal effective stress, but also upon the fluid which saturated the rock pore space. When confining pressure and pore pressure were equal (zero nominal effective stress), bit-tooth impact resulted in brittle failure for nitrogen-saturated Berea, and brittle to transitional failure for nitrogen-saturated Bandera; when saturated with liquid both rocks failed in a ductile manner at zero nominal effective stress. INTRODUCTION Dynamic wedge penetration tests have been conducted by investigators in several fields, but the failure mechanism of rock under dynamic stresses is not understood completely. The complex action of drilling bits, even considering the action of a single tooth, may be considered as a combination of drag bit and rolling cutter action. Thus, as a first step in understanding rock breakage in oil well drilling, single chisel impact and rock planing are of fundamental importance. For example, Gray 2 and Crisp3 studied drag bit cutting action at brittle stress states. Simon4 and Hartman5 studied the reaction of rocks to vertical impact by means of drop tests. The depth of penetration, crater volume and force-vs-time curves during crater formation were observed. The significance of indexing single-bit impacts has been noted.4,6-8 Gamer et al,9 reported impact tests on impermeable Leuders limestone at atmospheric and elevated confining pressures. In all cases the tests were accomplished on dry rock and pore pressure was considered to be zero. The importance of both confining pressure and pore pressure on the failure characteristics of rock was described. 10-12 It was found that the yield strength and ductility of porous rock depend on the state of stress under which the sample is tested. The importance of pore pressure on drilling rate in microbit experiments was noted by Cumingham and Eenink. l3 Robinson 12 also pointed out that in drilling the most important parameter in rock failure is the effective stress, where effective suess is defined as confining pressure pc minus pore pressure pp. The effect of pore pressure and confining pressure on rock strength was also noted by Serdengecti and Boozer 14 in strain rate tests, and by Gardner, Wyllie and Droschackl5 in elastic wave studies. Until recently all reported wedge impact studies under simulated wellbore stress states have been conducted on dry rock. Maurer 16 reported impact tests on samples saturated with deaerated water. Borehole and formation fluid pressures were equal in these tests except when mud was used in the borehole. With mud in the borehole and a high borehole-to-formation fluid pressure differential. Maurer observed "pseudoplastic" crater formation. Podio and Grayl reported impact tests on Berea and Bandera sandstone saturated with pore fluids having wide ranges in viscosities. In Podio and Gray's tests, confining pressure was elevated, but pore pressure and borehole pressure were held fixed at atmospheric pressure. The presence of

By Franz Wever

ACCORDING to Tammann,1 the explanation of the effect of mechanical deformation in producing changes in the properties of metals is one of the most important problems of physical metallurgy, taking rank with the study of the constitution of alloy systems; and this problem has long attracted-the attention of practitioner and scientist alike. Its solution was not advanced materially until Tammann2 set up his translation hypothesis with its crystallographic basis, while other hypotheses, such as the amorphous metal hypothesis of Beilby3 and Rosenhain,4 have been shown by more intensive studies to be less and less satisfactory. The principles of the Tammann translation hypothesis have proved to be useful even up to today and in spite of all of the recent accumulation of experimental data, while the differences of opinion which have arisen relate to the extent to which the hypothesis accounts for the observed changes in properties and to what extent further assumptions are necessary. Stimulated by the proposals of Tammann, there soon developed a lively experimental activity which aimed at the elucidation of the structural or crystallographic changes produced by the mechanical deformation of metals. Parallel movements of crystal "blocks" along definite crystal slip planes had already been observed by lowing and Rosenhain5 in 1900, in metals which had been moderately deformed but without shedding light on the crystallographic nature of the processes accompanying more severe deformation. The solution of this important problem was not advanced until a much later date, or until the methods of X-ray crystal analysis had become available. Shortly after the discovery of the diffraction of X-ray by crystals, symmetrical diffraction effects were

Jan 1, 1931

By W. P. Sykes

THIS investigation was undertaken primarily to establish the relations existing between temperature and mechanical properties in molybdenum, nickel, and an aluminum-copper alloy. Molybdenum (m.p. 2500° C.) was chosen because it is partly similar to tungsten and partly similar to the common ductile metals. Also it is known to furnish, by proper treatment, a desirable material to use in studying relation of grain size and physical properties. The molybdenum used was of the quality that is drawn into wire 0.003 in. in diameter for use as filament supports in incandescent lamps; chemical analysis shows less than 0.1 per cent. of impurities. Nickel belongs to the same class as iron. Its melting point is 1450° C. and an allotropic change at about 370° C. results in a loss of magnetism above that temperature. This feature made nickel doubly valuable for the purposes of these tests. The nickel used was obtained from the Driver-Harris Co. as 0.090 in. (2.3-mm.) wire, annealed; analysis showed 99.8 per cent. nickel and 0.150 per cent. iron. Aluminum is one of the low melting-point metals. Some tensile tests at elevated temperatures have been reported by Bengough but the possibility of learning more with the low temperature and sensitive apparatus available recommended this metal. The samples marked Al are an aluminum-copper alloy; they contained 3 per cent. copper, 0.42 per cent. iron, and 0.21 per cent. silicon. The presence of the copper somewhat complicates the analysis of the results; but the action of copper in aluminum has been studied so that its influence might have been foretold, in part at least. The material and analyses were furnished by the Aluminum Castings Co. The nickel wire, which was deformed at 400° C., was drawn under a bath of molten lead and through a die, which also was immersed in the bath. A thermocouple was suspended in the molten metal to indicate

Jan 1, 1921

By M. H. Waxman, L. J. M. Smits

A simple physical model was used to develop an equation that relates the electrical conductivity of a water-saturatedshaly sand to the water conductivity and the cation-exchange capacity per unit pore volume of the rock. This equation fits both the experimental data of Hill and Milburn and data obtained recently on selected shaly sands with a wide range of cation-exchange capacities. This model was extended to cases where both oil and water are present in the shaly sand. This results in an additional expression, relating the resistivity ratio to water saturation, water conductivity and cation-exchange capacity per unit pore volume. The effect of shale content on the resistivity index - water saturation function is demonstrated by several numerical examples. INTRODUCTION A principal aim of well logging is to provide quantitative information concerning porosity and oil saturation of the permeable formations penetrated by the borehole. For clean sands, the relationships between measured physical quantities and porosity or saturation are well known. However, the presence of clay minerals greatly complicates log interpretation, particularly the electrical resistivity and SP logs, and considerably affects evaluation of hydrocarbon-bearing formations. The conductance and electrochemical behavior of shaly sands and their relation to log interpretation have been studied by many workers. wylliel and Lunch2 reviewed this work in some detail. Virtually all laboratory measurements of electrical resistivity and electrochemical potential of shaly sands published to date are the work of Hill and Milburn.3 Their measurements were made on about 300 cores covering a large variety of sedimentary rocks, and a wide range of equilibrating NaCl solution concentrations. Hill and Milburn described their conductivity data by an empirical equation in which the shaly sand conductivity Co was expressed as a function of the solution conductivity C and two parameters b and F01 . The quantity b was shown to be a measure of the effective clay content of the rock, being approximately proportional to the cation-exchange capacity of the rock divided by its pore volume. The latter ratio is designated as 9, in this paper and has the dimensions meq/ml or equiv/liter. Qv is identical with the term representing the concentration of fixed charges in the Meyer-Sieved and Teorel15 theory of permselective membrane behavior. F01 is a formation resistivity factor referred to a hypothetical equilibrating solution resistivity of 0.01 ohm m at 25C,* where clay effects presumably are minimized. F01 was correlated to porosity by an Archie-type equation.6 The Hill-Milburn equation describes their data with a standard deviation of approximately 1 percent and a maximum deviation of + 10 percent. Shaly sands behave as permselective cation-exchange membranes, their electrochemical efficiencies increasing with increasing clay content. The electrochemical potential data of Hill and Milburn were expressed graphically, and demonstrate that the membrane efficiency (or cation transport number) of these sands is a function only of the b value (i.e., Qv) and the respective salt concentrations of the two solutions forming the liquid junction in the sand. The diffusion potentials are not dependent on F01 or any parameter relating to the porosity or pore geometry of the rock. The Hill-Milburn resistivity equation correctly predicts a decreasing sand conductivity Co with decreasing solution conductivity C?. However, at some low value of C,, the calculated Co-C, function goes through a minimum; with further decrease in C?, the predicted sand conductivity increases sharply. As pointed out by Hill and Milburn, an increasing value of Co with decreasing C, is physically meaningless. Since this occurs below the range of practical values of C,, the usefulness of the empirical equation is not affected when

Jan 1, 1969

By G. Derge, R. E. Grace

Diffusivity of bismuth in liquid Pb-Bi alloys has been measured by the capillary reservoir method as a function of temperature and composition. Fair agreement between theory and experiment is found for the measured diffusion coefficients and activation energies of diffusivity and viscosity in dilute lead alloys. The measured diffusion coefficients in the high bismuth alloys describe mass transport in special concentration gradients. THE study of diffusion in liquid metals has been restricted largely to the amalgams over small ranges of temperature and composition. In contrast to this, diffusion and transport of ions and molecules in aqueous and organic solvents have been studied extensively for the past 50 years. The general difficulty of measuring diffusion coefficients in both gases and liquids at high temperatures has been that of eliminating convection currents. Measuring techniques based on freezing and sectioning after the diffusion period1 are not particularly satisfactory because of the volume changes and segregation which occur during freezing. The most promising technique which is currently being developed for liquid metals is the capillary reservoir method. This eliminates convection currents from the diffusion zone and requires measurements only of the length and initial and final compositions of the alloy within the capillary. Anderson and Saddington' have measured the diffusion coefficient of tungstate anions in aqueous Na,W04; Wane4' and Hoffman- ave studied structure and self-diffusion in water and self-diffusion in mercury, respectively, by similar techniques. Selection of the Pb-Bi system for initial study was made for several reasons: I—It afforded a low temperature system for development of techniques which would be suitable for high temperature measurements in liquid iron. This research on diffusion in liquid iron is now in progress as a part of a general program on the rates and mechanisms of slag-metal reactions. 2—Activity data on liquid Pb-Bi alloys of all compositions are available from the emf meas- urements of Strickler and Seltz.9 3—Some data are available on the diffusion of bismuth into solid lead. The measurements on solid alloys were made by von Hevesy and Seith7 for the concentration range of 0 to 2 pct Bi. An appropriate solution to Fick's law (unsteady state) for the capillary reservoir has been found by considering the mass flow which passes through a unit area of surface on a slab of infinite thickness as a function of time. This is the first application of this solution to diffusion measurements, although a similar solution is available for identical boundary conditions.' By analogy with heat conduction, the problem reduces to a perfectly insulated infinite slab at temperature C,, one surface of which is quenched to C, for all times, t. Heat is permitted to flow from quenched surface of the slab to an infinite supply of coolant at C.' (see Appendix). For the corresponding solution for diffusion in liquids, these terms become Where Cu is the initial concentration of component A" in entire capillary at t - 0, C, is the final con- In this case. component A is bismuth, and C, = 0. centration of component A in entire capillary at t = t, C, is the concentration of component A in bath for all t, 1 is the length of the capillary in centimeters, t is the time of diffusion period in seconds, and D is the diffusion coefficient in square centimeters per second. By comparison with solutions to Fick's law used in the solid state, this solution for liquids is similar to the Grube solution for solids, where the change in D with chemical composition is not taken into consideration. Difficulty is to be expected if large concentration gradients are employed and if the concentration gradients extend over an appreciable length of the capillary.

Jan 1, 1956

By Rudolph G. Wuerker

MUCH descriptive matter[ ] has appeared on the subject of suspension roof supports, or roof bolting, as it is more commonly called. The wide- spread introduction of roof bolting into coal mines and metal mines is truly phenomenal. Mine operators were quick to recognize the advantages of supporting wide openings without hindrance to machine maneuverability and ventilation.

Jan 6, 1953

Jan 1, 1920

By A. M. Gaudin

Activation of sphalerite with silver ions results from the exchange of two Ag ions for one Zn ion in the sphalerite lattice. The exchange is proportional to the logarithm of time and proceeds until either of the reactants is consumed. Sodium cyanide prevents the activation of sphalerite by controlling the ratio [Zn++]/[Ag+]' in solution. If sphalerite has already been activated with excess silver, cyanide ions can deactivate sphalerite provided oxygen is present. SOLUBLE: silver salts are effective activators for flotation of sphalerite with potassium ethyl xan-thate as collector.* Since sphalerite takes up large quantities of silver ions rapidly,2-4 investigation of this system appeared fruitful for studying the mechanism of sphalerite activation and deactivation. Experimental data presented here comprise studies of the mechanism and rates of activation and deactivation of sphalerite with silver and cyanide ions. A 20-lb sample of sphalerite from Ottawa County, Oklahoma, was handpicked, crushed, screened, hy-drosized to produce a 65/100-mesh fraction, and purified by electrostatic separation. The sphalerite was then leached with benzene and absolute ethyl alcohol to remove possible organic contaminants and with 0.1 M NaCN to remove any copper that might have been picked up during screening. The benzene had been specially purified by grinding with fine sphalerite for 12 hr to remove trace impurities that might have had a specific affinity for sphalerite. Ii'inally, the mineral was washed, dried in flowing nitrogen, and stored in large ground-glass stoppered weighing bottles under a small nitrogen pressure. The specific surface of two samples from the 65/100-mesh sphalerite stock, measured by krypton gas adsorption," was 420 cm2 per g. Compared with spheres of the same size and specific gravity, the prepared mineral had five times as much surface. Results of a wet chemical analysis and of a spectro-graphic study are given in Table I. Manganese, nickel, tin, indium, thallium, cobalt, and magnesium were not detected spectrographically. All solutions were preparid by -adding reagent-grade chemicals to conductivitv water. which had been previously saturated with the desired gases. Nitrogen and oxygen were purified, but no attempt was made to purify the laboratory air. Radioanalysis was carried out with prepurified Ag110 tracer obtained from the Oak Ridge National Laboratory. The complete decay scheme for Ae is complex. Its primary emissions are 0.09 and 0.55 mev ß rays and 1.48 mev y raysB and its half-life is believed to be 270 days. In preparation of solutions of AgNO3, the amount of Ag110 added was negligible compared to that of the inert silver. Abstraction of silver from solution by sphalerite was measured after agitation of 1.5 g sphalerite with 20 ml of solution in 50-ml pyrex flasks. All sample preparations were carried out in a dry box so that the proper atmosphere could be maintained. After the mineral had been agitated in the silver nitrate solution, an aliquot of the solution and a sample of the wet mineral were transferred to separate counting vials and weighed. The solid sample was dried and re-weighed and the activity in both vials measured by means of a scintillation counter. With scintillation counting it is possible to count y radiation from the solid and liquid, a distinct advantage over the older ß-ray counting techdiques.4 All measurements of silver activity were made using a sodium-iodide well-type scintillation counter. The amount of zinc in solution was measured colorimet-rically by the monocolor method of Sandell.7 Activation Studies Exchange Between Zinc Ions and Silver Ions During Activation: The increase of Zn++ in solution during activation with Ag+ is shown in Table 11. These data indicate a replacement of one Zn++ by two Ag+. Analysis of a separate two-month agitation test indicated that the replacement of Zn++ by Ag+ was, as expected, in the molar ratio of 2.0.

Jan 1, 1958

By R. B. Toombs

The national and international importance of Canada's minerals and metals producing industry is reported. The growth of the Canadian industry is traced from 1945, through the period of rapid development of the early 1950's, to the consolidation and expansion activities of the late 1950's and early 1960's. Mineral production in Canada during 1963-including steel, nonferrous metals, and fuels -is reported. It is estimated that by 1970 the Canadian industry will produce $3.9 billion worth of metals, nonmetals, and fuels.

Jan 8, 1964

By F. L. Bosqui

INTRODUCTION The history of the development of gold metallurgy in South Africa is divisible into two periods: That preceding the introduction of the cyanide process on a commercial scale in 1890; and the 24 years intervening between that important event and the present time. The period between the discovery of the banket reefs of the Witwatersrand and the year 1890 was one of phenomenally rapid progress in mining development, but of no special interest to the metallurgist. There were no strikingly original or distinctly local advances in the treatment of gold ores. Californian practice in stamp milling and amalgamation prevailed, in mills ranging in equipment between 5 and 50 stamps, operating within a wide range of efficiency, and under the trying conditions usually en¬countered in a new and isolated field. The somewhat incomplete records of gold output of that period show that in December, 1887, there were 20 producing companies in the Witwatersrand district, of which 10 had mills, the largest being of 20 stamps. The only official record of returns for May, 1887, was that of the Wemmer mine, whose modest achievement with a 5-stamp, mill was 100 tons crushed, producing 887 oz. 3 dwt. of gold. This is interesting in view of the .present-day output of this field, which in 1913 reached 8,430,998 oz. The rapid increase of production during this first period (May, 1887, to January, 1891) is shown by the following summary for the year 1890:1 Total tons crushed 702,828 Number of stamps in operation 1,046 Average number of tons crushed per stamp per day 2.36 Yield of gold, ounces 494,817 Yield per ton, pennyweights 13.36 The stamp duty ranged between 1 ½ and 4 tons per day, according to weight of stamp, fineness of screen, and operating skill available. The prevailing weight of stamp was about 900 lb., and the screen, 900 meshes to the square inch.

Jan 5, 1915

By R. D. Reiswig, J. M. Dickinson

The 0s-Ir equilibrium diagram was determined. The diagram is of the simple peritectic type, with a peritectic temperature of about 2660°C. The solid miscibility gap is narrower than previously reported, the nearly vertical solvus lines occurring at about 42 and 63 wt pct 0s. Widmanstaetten figures resembling martensite in some of the two-phase alloys account for a previously suspected transformation. In view of the long history of use of such alloys, it is surprising that the 0s-Ir equilibrium diagram has not yet been completely determined. The boundaries of the miscibility gap in this system have been estimated to be between 24 and 39 wt pct 0s and 79 and 100 wt pct OS. It has been predicted3 that alloys of ruthenium, osmium, and rhenium with the fcc platinum metals should solidify peritectically in their two-phase regions. The metallographic examination of natural osmiridium alloys has been said4 to indicate, by the presence of a martensitic structure, the existence of a transformation or a phase separation. On the basis of superconducting transition temperature measurements, a 70 at. pct 0s alloy was found5 to be two-phase prior to annealing. EXPERIMENTAL The elemental components used in this work were obtained from several suppliers as sponge. The purities, stated by each supplier to be in excess of 99.8 pct, were confirmed in each case by a semiquantitative spectrographic analysis. The pure components were premelted in an inert-gas tungsten arc furnace with the evolution of some fume, crushed, and pickled for use as alloy melting stock. Upon arc melting to the final compositions, no fume evolution was observed. Because weight losses of the order of 15 mg or less were observed in preparing alloy buttons weighing 15 g, "synthetic analyses" were used in determining the compositions of the alloys. Alloys used in this investigation contained 15, 20, 33, 40, 42, 43, 45, 50, 55, 60, 63, 64, 66, 70, 79, and 80 wt pct 0s. Heat treatments of the alloy buttons and pieces thereof were performed in a previously described6 tungsten tube furnace under pressures of 105 torr or less. It was found that homogenization treatments on the specimens were essential to remove the severe coring which was present, a 3-hr treatment above 2300°C removing all the metallographi-cally visible evidence of coring. Following the various heat treatments, the specimens were "vacuum-quenched" by melting a tungsten fuse wire and allowing them to drop onto a water-cooled copper plate. In a few instances, specimens were quenched into molten tin for comparison, but no difference was apparent. Vacuum-quenched specimens cooled from 2400°C to below a red heat in less than 60 sec. Typical equilibration times varied from 3 hr above 2300°C to 88 hr near 1100°C. The utilization of successively longer equilibration times and the approach to equilibrium from both directions indicated that the times used were sufficient to give a close approach to true equilibrium. Heat-treatment temperatures were measured with a calibrated Leeds and Northrup optical pyrometer through a 0.120-in. lateral sight hole in the tungsten heater tube. It was known that the assumption of black-body conditions inside the 1-in.-diam by 10-in.-long tube was unwarranted. The empirical results of work with thermocouples and melting

Jan 1, 1964

By E. Bicknese, R. Clark

The mechanism and rate of reduction of FeO at conditions similar to those in the stack of a blast furnace have been determined for temperatures from 980" to 1165°C. Preliminary studies of the reduction of Fe2O3 with activated coconut charcoal in a static system (no flow of reducing gas) have shown that the CO2-CO ratio of the product gas depends upon the relative reactivities of the Fe2O3 and charcoal. In a systern with a "hot blast" of CO and Nz (simitar to dry bosh gas), synthetic FeO, and actiuated coconut charcoal, the rate of reduction was not sensitive to the flow of reducing gas, and the rate-controlling step alas the chemical reaction at the metal-oxide interface. Wherz solid carbon was not present, a critical flow rate of reducing- gas had to be met in order to prevent a lowering of the reduction rate. The effect of a less-reactive carbon (blast-jurnace coke) and of a "natural" FeO on the mechanistn and rate, and the mininum amount of carbon necessary in the charge to tnaintain the reducing potential of the gas phase, have been determined. THE importance of iron oxide reduction processes has encouraged many studies of the process reaction kinetics. Despite this, the mechanism is not well-understood and three main theories have evolved, which can be stated as follows: A) the rate-controlling step is diffusion, either gaseous diffusion of the reductant or product gas through a porous solid,' or solid-state diffusion of iron and oxygen atoms through the so1id.2 B) The slow step is diffusion of reducing gas through a stagnant boundary layer. C) The reaction rate is controlled by the chemical reaction occurring at the metal-oxide interface and is proportional to the area of this interface.3 By increasing the velocity of the reducing gas to a flow rate beyond which no increase in the reduction rate is observed, critical flow rate, it may be possible to eliminate B as the slow step. However, as warnere points out, the establishment of a critical flow rate may only assure that the reaction is not limited by a reduction in the reducing potential of the gas and that B may still be the rate-determining step. Edstrom and Bitsianes and Seth and Ross8 show that A and C may both be correct for the reduction of the same oxide, depending upon the stage of the reduction, and that the relative importance of the two mechanisms varies with the porosity of the oxide. Themelis9 has derived expressions which express A, B, and C in terms of the fraction reduction, Rx, of a spherical particle. Thus, in the case of A a plot of In (1 - Rx) vs time must be linear and the time to reach a given reduction is proportional to the square of the particle diameter. For B a plot of (1 - Rx) vs must be linear and the time to reach a given reduction is proportional to the square of the diameter. For C a plot of 1 - (1 - RX)1/3 vs f must be linear and the time to reach a given degree of reduction should be proportional to the diameter. In the case of mixad controlled reactions, none of the plots are linear over their entire length. The results of previous studies, in which the rates of gaseous reduction of iron oxide were measured in the absence of carbon, may not correspond to blastfurnace practice because they ignore the effects of the Boudouard reaction. CO2 +C — 2CO The presence of carbon may alter the mechanism or the rate of iron oxide reduction through an enrichment of the gas phase by Eq. [1]. In this case, the presence of and reactivity of carbon become important. If the Boudouard reaction has no effect on the rate of reduction, the reducing gas could be supplied by some means other than the gasification of carbon at the tuyeres and carbon could, theoretically, be eliminated from the burden. Preliminary studies of the reduction of Fe2O3 with activated coconut charcoal were made to determine if the reactivity (surface area) of the Fe2O3 had any effect on the product gas composition. Two size fractions of Fe2O3 were reduced with charcoal in a static system (no flow of reducing gas). In each case the charcoal was -100 + 325 mesh and was 25 pct of the total charge. One fraction of the reagent-grade Fe2O3 was submicron in diameter. The other fraction was -100 + 200 mesh and was prepared from the former by compacting, sintering at 1300°C, crushing, and screening. In each experiment, the reaction vessel was filled with a mixture of CO and CO, which would be in equilibrium with FeO and iron at the reaction temperature. A furnace was heated to the desired temperature, the vessel was placed in the furnace, and the gaseous products of the reaction were collected and analyzed. The results of these experiments, Fig. 1, show that the gas phase associated with the submicron oxide is more oxidizing than that with the -100 + 200 mesh oxide. Therefore, in a static system, the relative rates of the reduction reaction and the gasification of carbon depend upon the reactivities of the Fe2O3 and charcoal. The reduction of FeO to iron is the most important reaction occurring in the blast furnace and is probably the slowest of the several reduction steps. The mechanism and rate of reduction of FeO in a system containing carbon and a flow of dry bosh gas have been studied. TRANSACTIONS OF THE METALLURGICAL SOCIETY OF AlME

Jan 1, 1967

By J. L. Moriarty, Irving Johnson, H. M. Feder

The crystallization of ternary alloys has been studied as a coprecipitation phenomenon by measuring the substitutional carrying of trace metals with CeCd11 precipitating from liquid cadmium. The Doerner-Hoskins logarithmic distribution law has been found to apply in all cases; the coprecipitation coefficients obtained were: 1.48 (La), 1.06 (Th), 0.63 (Pr), 0.24 (Gd), 0.17 (Sm), 0.13 (U), 0.10 (Er), 0.09 (Sr). Li, Na, K, Ba, Y, Sc, and Zr were not measurably carried. It has been observed that coprecipitation was most extensive for those tracers which form with cadmium an intermetallic compmdnd isostructural with CeCd11 or closely related thereto. For these tracers an inverse relation between Solubility in cadmium and coprecipitation coefficient was noted. THE partition of impurities between the liquid and solid phases of a metal or a congruently melting intermetallic compound has been extensively studied by the methods of zone melting.' However, when the composition of a liquid alloy and of the solid phase crystallizing from it differ grossly, partition of an impurity cannot be investigated in this manner. Partition of the impurity under equilibrium conditions may be studied by investigation of the appropriate phase diagram and partition under nonequi-librium conditions may be studied by observation of coring in the solidified alloys.2 The nonequilibrium case is of special interest in metallurgical practice because many complex alloys are cooled too rapidly to permit the uniform diffusion of impurities throughout the crystallizing phase(s). With this in mind, the present study was undertaken to obtain quantitative data on the phenomenon of coprecipitation via substitutional solid solution in certain metallic systems. It will be noticed that rather than adopting metallurgical ter- minology we have chosen to refer to the partition of impurities during alloy crystallization as coprecipitation.3 In the terminology of coprecipitation the impurity is referred to as the tracer and the precipitating phase as the carrier. From aqueous solution, coprecipitation may occur as a result of adsorption on the surface of the carrier, by occlusion of the liquid within the crystals, or by solid solution of the tracer in the carrier. By slow cooling of liquid metallic solutions it is relatively easy to form large, regular crystals of the carrier; the effects of adsorption and occlusion may be minimized and the influence of substitutional solid-solution formation may be made to predominate. Previous studies of the crystallization of some intermetallic compounds4 and of copper, silver, and gold5 have shown that the coprecipitation or partition behavior of trace metals is entirely analogous to that observed in aqueous systems when ionic substitution occurs, e.g., coprecipitation of Ra++ with BaSo4. The precipitation of CeCd11 from liquid cadmium was chosen for study. This choice was influenced by the following consideration. If the relative atomic sizes of the tracer atom and the atom for which it substitutes determine the tendency to coprecipi-tate, then a lattice having a substitutional site of well-defined size would be desirable. In CeCd116 (structure type cubic BaHg117) the cerium atom is completely surrounded by a cage of twelve nearly equidistant cadmium atoms. Thus, atoms much larger or much smaller than cerium should be poorly accommodated in this cage. The choice of a lanthanide central atom allowed the testing of the size hypothesis with a number of lanthanide tracers which differed in size but not in valence or electro-negativity. EXPERIMENTAL The general technique of this investigation was to prepare a slightly undersaturated solution of carrier in liquid cadmium to which a tracer was added. The concentration of tracer was always so low that saturation over the entire temperature range investigated was never exceeded. The solution was cooled in a stepwise fashion. After each step a por-

Jan 1, 1964

By John H. Walthall, Raymond L. Copson, Travis P. Hignett

In October 1942, the War Production Board requested the Tennessee Valley Authority to undertake investigations to determine the feasibility of producing alumina suitable for reduction in aluminum cells, from clays and other domestic materials, by a lime-sintering, soda-ash leaching process. The work was undertaken by the chemical engineering staff of the Authority under the general direction of the War Metallurgy Committee of the National Academy of Sciences. The investigation included small-scale tests to determine the most suitable conditions for the process, and construction and operation of a pilot plant to obtain data for evaluation of the process and for design of a plant. The results of this investigation are described in the present paper. Sources of Alumina Alumina for the commercial production of aluminum is obtained from bauxite by the Bayer process. The tremendous demand for aluminum for wartime uses is causing rapid exhaustion of the high-grade bauxite deposits in the United States. On the other hand, there is an abundance of aluminous materials such as clay and lower grades of bauxite, which are not suitable for treatment by the Bayer process because of their high silica content. The Tennessee Valley Authority has conducted research and pilot-plant work for more than 5 years on methods for the production of alumina from clay and low-grade bauxite. Particular attention has been given to the high-grade white kaolin found in Carroll County, Tennessee. Exploratory drilling has demonstrated that at least 4 1/2 million tons of kaolin containing in excess of 34 per cent AlzOI is available in this area by strip-mining methods. It has been estimated that hundreds of millions of tons of clay of similar quality occur in the Tennessee Valley region. The Process The process is illustrated in the flowsheet (Fig. I), and consists essentially of the following steps: I. Heating a mixture of clay and limestone to form a sinter containing calcium aluminate and dicalcium silicate. z. Leaching this sinter with a dilute sodium carbonate solution, to form a sodium aluminate solution and a calcium carbonate, calcium silicate residue, which is discarded. 3. Treating the sodium aluminate solution with carbon dioxide to precipitate aluminum trihydrate and regenerate the sodium carbonate solution, which is recycled. 4. Heating the aluminum trihydrate to produce alumina. The process was considered promising because of the abundance and cheapness of the two raw materials, clay and limestone; and because, as compared with an acid process, smaller amounts of critical

Jan 1, 1944

By Francis Freeland

An examination of accessible English literature shows that but small space has been allotted to the determination of faults ; most suggestions being confined to Schmidt's rule of the downthrow on the hanging-wall of the fault, or the coal-miner's rule of the obtuse angle. Von Carnall's modification of Schmidt's rule is sometimes given without the important exception, and Zimmermann's rule is

Jan 1, 1893

By J. J. Pye, J. B. Drew

The surface-diffusion coefficients of Ni63 diffusing on low-index planes of nickel single crystals have been measured over the temperature range from 400° to 1000°C using a precision autoradio-gvaphic technique. The activation energy for sur -face diffusion appears to he the same on the {111}, {110), and (100) planes and amounts to -0.60 ev. This is in good agreement with the value (-0.62 ev) reported for (111) planes obtained by mass-transport techniques. In an earlier paper, the authors have reported self surface-diffusion coefficients on silver.' In that work, a deviation of the diffusion coefficients from linearity in the Arrhenius plot was observed at high temperatures. This effect was attributed to a loss of tracer atoms into the bulk by volume diffusion. The purpose of the present work was to extend the technique developed to the nickel surface-diffusion system up to the point where volume diffusion would come into play. The nickel system especially lends itself to this technique due to the high efficiency of the isotope in darkening the film and the large absorption of the weak radiation (0.063 mev /3- particle of the trapped tracer atoms. The diffusion coefficients and ictivation energy for different orientations on nickel can also be compared with a report published by Blakely and Mykura 2 where a mass-transfer technique was used. This paper reports the self surface diffusion of nickel on the low-index planes over a wide temperature range using a precision autoradiographic technique. EXPERIMENTAL PROCEDURE The experiment is similar to that described in the earlier publication consisting of a radioactive needle as a source resting on a flat, smooth, chemically polished surface annealed in a dynamic dry-hydrogen atmosphere. The needle is held snugly on the surface by a holder fabricated from commercially pure nickel. The point source is made by grinding down a small-diameter nickel rod until a tip of approximately 0.1 mm radius is formed. It is then etched and the needle tip plated with the radioactive isotope Ni63. Nickel single crystals were used whose main impurities were spectrographically determined as Co 0.05, Fe 0.007, C 0.005, and S 0.003 pct. The surfaces, oriented to within 1/2 deg of the low-index planes, were carefully mechanically polished and etched in a 50-30-10-10 hot solution of acetic, nitric, sulfuric, and phosphoric acids giving a smooth polished surface. The crystals were then washed in distilled water and alcohol. Annealing temperatures ranged from 400° to 1000°C with a furnace arrangement in which the crystals could be brought up to temperature in times short compared to diffusing times. The temperature was maintained constant to ±10°C. In the temperature range investigated, the ratio of the surface-diffusion coefficient to the volume-diffusion coefficient (Ds/Du) was 105 or more and the mean bulk-penetration values, calculated from literature values of volume-diffusion coefficients,3 were on the order of 10-5 cm. After the diffusion anneal, the sintered needle is removed, and both the radius of the needle point and spot left on the crystal face are measured. The crystal is then placed on photographic film. Diffusion profiles are obtained by scanning the film with a recording microdensitometer which has a slit width of 10µ. DISCUSSION AND RESULTS The experimental conditions are such that the source strength and needle radius are essentially constant and the time is adjusted such that the mean bulk penetration is small. An exactly analogous heat-flow problem has been considered by Carslaw and Jaeger4 and the solution can be written in integral form as:

Jan 1, 1964

By H. A. Koch, R. L. Slobod

This paper discusses a new oil recovery process called the "miscible slug process." This process involves the injection of propane or LPG into the reservoir prior to gas injection. The operating conditions are maintained so that the slug is miscible with both the reservoir oil and the injected gas phase. Thus, a miscible phase displacement is achieved, and high recoveries are obtained from the area of the reservoir contacted. The most striking discovery of the laboratory study which included displacements from cores up to 123 ft in length was that relatively small slugs of LPG are effective over reservoir distances in the miscible displacement of oil. This makes possible the commercial application of the process. The important factors controlling the size of the slug are: (I) reservoir length, (2) reservoir fluid composition, and (3) reservoir pressure at the displacement front. Of lesser importance are the effects of injection rate and porous medium type. Questions which have not been completely answered deal with the effects of gravity and reservoir inhomogeneities on the process. INTRODUCTION One of the major problems facing the oil industry today is recovery of the large fraction of the discovered oil which will remain unrecovered unless some new processes are found. Water flooding has been one successful method used to increase recovery over natural depletion. But even successful water floods may leave 25 to 40 per cent of the pore space filled with residual oil. Recently a process which involves the use of thermal energy has been reported1,'*' which may prove useful in increasing recovery from shallow reservoirs containing highly viscous crudes. This paper deals with a new oil recovery process involving use of miscible phases to displace the oil from the reservoir. Miscible phase displacement oil has been an intriguing idea because the elimination of capillary effects in the reservoir leads to 100 per cent recovery in the areas contacted by the miscible displacing phase. The big deterrent in the past to the practice of miscible phase displacement has been the high cost involved in using large volumes of solvent in the process. The use of high pressure gas to achieve a miscible phase displacement of reservoir oil has been reported4,5 as one economically feasible method. However, this process calls for the maintenance of pressures above 3,000 psi at the dis-placement front. The process described in this paper is not restricted to high reservoir pressures; the only qualification being that the slug of material which is injected into the reservoir must be miscible with both the displaced oil 2nd the displacing phase. Two such cases are the use of an alcohol slug followed by water to achieve a mis-cable water flood, and the use of a low boiling hydrocarbon slug such as propane followed by gas to achieve a miscible gas drive. This paper will deal specifically with the propane dug process. This process will obtain a miscible phase displacement at pressures as low as about 1,200 psi at a reservoir temperature 01 150°F. The process is very simple. The propane displaces oil completely at one front because it is miscible with the oil, and gas displaces the propane completely at a second or trailing front because it is miscible with the propane. A small band of propane should thus remain wedged between the gas and oil phases. This idea has been called the "miscible slug process."6 Unfortunately, the propane slug will become diluted as it flows through the reservoir. This results from a mixing action since the fluids flow through a complex reservoir porous medium rather than simple capillaries. Fig. 1 diagrams a miscible slug displacement. The effects of some of

Jan 1, 1958

THE composition and quality of finished steel depend upon selection and proportioning of the raw materials of the charge as well as upon control of furnace practice. This chapter deals only with the raw materials of the basic open-hearth process that are important in determining the composition of the steel or slag. They are the metallic charge, oxygen-bearing materials, fluxes, alloying and deoxidizing additions, and certain refractory materials used for maintenance of bottoms. Other refractories, which may affect the slag composition, are discussed in Chapter 3. Wide variations are possible in the type and composition of charged materials but certain limiting relations among the elements of the charge must be observed. Since the process consists essentially of refining by the oxidation of undesired dements, a balance must be established between the sources of oxygen and the elements in the charge that are subject to oxidation (see Chapters 2 and 7). For example, if it is desired to use a high ratio of blast-furnace hot metal to scrap, it is necessary to add an oxygen-bearing material such as ore or mill scale to eliminate the excess carbon and silicon that are present in the hot metal. An example of the opposite extreme is the use of a metallic charge composed entirely of steel scrap. With this type of charge, it is common practice to substitute burnt lime for limestone as a flux and to charge some carbonaceous material such as coke to avoid an excess of oxygen in relation to the elements of the charge that are subject to oxidation. Elements such as copper and nickel, which are not oxidized or eliminated by, any other reaction, may be introduced into the charge only to the extent to which they are permissible in the finished steel. An example of adjustment of the charge for elements of this type is found in the use of steel scrap high in copper. In this case, metallic components of the charge other than the scrap should be low in copper, or a sufficiently high ratio of pig iron to scrap should be charged to dilute the copper from the

Jan 1, 1951

NEW MEMBERS. The following list comprises the names of those persons who became members during the month of September, 1913: Members. ANDERSON, ANDREW P., Min. Engr 908 Story Bldg., Los Angeles, Cal. ANDROS, STEPHEN 0., Min. Engr University of Illinois, Urbana, Ill. BECKETT, PERCY G., Min. Engr Globe, Ariz. BLAIR, THOMAS S., JR., Prest. Blair Engrg. Co 343 S. Dearborn St., Chicago, Ill. BOYLE, HARRY, Min. Engr S07 Lowman Bldg., Seattle, Wash. BRADEN, EUGENE B., Vice-Prest., Selby Smelting & Lead Co., Merchants Exchange Bldg., San Francisco, Cal. CHALMERS, JOHN W., Min. and Elec. Engr., Morro Velho, Villa Nova de Lima, Honorio Becalho Minas Geraes, Brazil, So. America.

Jan 10, 1913

By K. Osseo-Asare

The presence of carbonaceous matter in gold ores presents a two-fold problem: (1) The poor release of gold from the carbonaceous matrix and (2) the uptake of dissolved gold by the carbonaceous leach residues. A critical review is presented of the published information from various parts of the world pertaining to the nature of the carbon-containing components of these ores and their different roles in the gold extraction process. Included in this paper are new results based on the authors' research on carbonaceous ores from the Prestea goldfields of Ghana. Methods for isolating and characterizing the carbon-containing materials are given and a discussion is presented of the interaction of the carbonaceous ores as well as the fractionated components with aurocyanide solutions. Emphasis is on basic physico-chemical phenomena, investigated with the aid of X-ray diffraction, infrared spectroscopy, adsorption, and electrophoretic mobility studies.

Jan 1, 1984