Search Documents

By B. C. Allen

Grain-boundary gvoocing was studied irz chronziu?n. molybdenum, tungsten, and the solid-solution alloys, Cr-35Re. Mo-33Re, and W-25Re at 0.6 to 0.9 of the absolute liquidus temperature under an inevt atmosphere , foveign nzetal zlapor, and liquid metal. The controlling mechanism of matter transport was deduced frolr groove size and shape. kinetics of growth, and cotnparisoz with theoretical relatiotzships derived by Mullins. Grooves in chowzizon formed prittzarily by volume diffusion tkrongk kelium or argon at 1 atm pressure and by e1)apovation-condensatiotz in a static vacuum. Groozles in the other nzetals and alloys forrned priniarily by sirface diffusion, the coefficients of which were calculated. Carbon was found to decrease the acti7:ation energy for surface diffusion on molybdenun. Sitrface diffusizities weve sinzilav for iWo-0.0ZC and Mo-33Re. The presence of about 1 -?nm pressure of silver or tin vapor did not affect the neckanis)n of grooz;e formation. In liquid titz or silz:er, pain bolindary gvooves formed by zolume diffusion in the liquid. BASED on theories of ullins," the mechanisms of grain-boundary grooving have been determined for low-melting metals such as copper in an inert atmospheres or in liquid lead.4 The purpose of this investigation was to study grain-boundary grooving in the refractory Group VI-A metals, chromium, molybdenum, and tungsten, and the bcc solid-solution alloys, r-35e, 0-33e,= and -25e,' at 0.6 to 0.9 of included to see whether Mullins' theories were applicable to them as well. EXPERIMENTAL WORK The materials chromium, molybdenum, tungsten, Cr-35Re, Mo-33Re, and W-25Re were in the form of 0.050-cm-thick sheet assaying 99.98 pct or better. The nominal carbon level was generally 30 ppm. The oxygen + nitrogen + hydrogen content was -50 ppm. Mo-33Re and W-25Re were prepared by powder-metallurgy methods and supplied by Chase Brass and Copper Co. The remaining materials were arc-cast. Chromium and Cr-35Re were prepared at Battelle by arc melting, extruding, swaging, and rolling. Mo-0.003C was supplied by Climax Molybdenum Co., and Mo-0.02C and tungsten by Universal Cyclops Corp. As a source of liquid metals, tin and silver granules assaying 99.98 pct were used. Spectrographic analyses indicated the presence of -100 ppm each of iron and silicon. Vacuum melting reduced the combined gas content to c5 ppm (2.60,, 0.9N2, 0.4H2 in tin and l.602, 0.7N2, and c0.04H2 in silver). Specimens were prepared for grain-boundary grooving. Coupons 0.5 by 1.5 cm with a small hole in one end, or substrates 1.5 by 1.5 cm, were cut from sheet. The specimens were annealed in containers of the same material to provide a vapor-solid equilibrium as well as to protect them from gaseous impurities. Outgassing was done at 2 x 10"5 mm for 15 to 30 min at 1150°C for chromium and Cr-35Re, 1750°C for molybdenum and Mo-33Re, and 2600°C for tungsten and W-25Re. Then recrystallization to a stable grain size of about 0.5 mm was accomplished by annealing at least 1 hr at 1600°C for chromium, 1800°C for Cr-35Re, 2350°C for molybdenum, and 2300°C for Mo-33Re in a rhenium-element resistance furnace under 1 atm of static argon or helium. The atmosphere was gettered by tantalum radiation shielding. Tungsten and

Jan 1, 1967

By A. Lubinski, J. E. Hansford

Rotating drill pipe passing through dog-legs suffers fatigue damage due to cyclic bending stresses. Curves of the cumulative fatigue damage incurred in either steel or aluminum drill pipe going through Such dog-legs are presented. These curves provide means for properly planning the rate of angle build-up in directionally drilled wells and allow discarding of drill pipe which has been fatigue-damaged in dog-legs. INTRODUCTION Drill pipe which is subjected to bending as it rotates, experiences a cyclically varying bending stress. If this bending stress is sufficiently large, the drill pipe is fatigue-damaged by each revolution, and ages as fatigue damage accumulates. Drill pipe can be bent intentionally, as in the case of directionally drilled holes, or unintentionally due to unde-sired changes in hole direction caused by variations in formation properties, weight on bit, etc. These changes in hole direction, whether intentional or unintentional, are called dog-legs. The theoretical limits of dog-legs which are permissible before the drill pipe begins to fatigue can be calculated.' However, in wells where the maximum permissible dogleg is exceeded, the concept of cumulative fatigue damage can be used to estimate damage suffered by the drill pipe. This concept has already been used to estimate the cumulative fatigue damage of drill pipe due to drilling vessel roll.' The purpose of this paper is to extend the usage of the cumulative fatigue damage concept to drill pipe in doglegs, and to draw conclusions which may be beneficial in preventing numerous frustrating and expensive drill pipe failures. FATIGUE OF STEEL DRILL PIPE IN IDEALIZED GRADUAL AND LONG DOG-LEGS It is taken for granted that, if necessary, the reader will become familiar with the definitions and concepts which follow by examining the reference cited in each case. For Ref. 1, it will suffce to read only through the section Abrupt Dog-Legs. 1. Concept of the two extreme kinds of idealized doglegs: gradual and long dog-legs and abrupt dog-legs,' 2. Concept of why the bending moment in drill pipe un- der tension is the largest in the vicinity of the tool joint,' 3. Concept of why dog-leg severity which drill pipe can withstand decreases with an increase in tension,' and 4. Definition of the rate of change of over-all hole angle (dog-leg severity)." Figs. 1 and 2 indicate the aging (fraction of life expended) of steel drill pipe passing through a gradual and long dog-leg. Both figures have a left-hand ordinate scale labled Length of Drill Pipe Below Dog-Legs. This scale can be used for cases in which the drill collar weight is applied to the bit and does not contribute to the tension in the drill pipe. It can be used for either 3 1/2-, 4 1/2- or 5-in. drill pipe. This is due to the fact that, if the drill collars do not contribute to the drill pipe tension, then the effect of pipe tension on bending due to a change in pipe size is nearly compensated for by a corresponding change in pipe rigidity. On the other hand, if drill pipe is rotated off bottom, then drill collars contribute to the tension in the drill pipe and this increase in tension is not compensated for. In this case, one of the three right-hand ordinates must be used (the one which corresponds to the correct drill pipe size). In the right-hand ordinates, tension should be understood as the weight in mud of the portion of the drilling string below the dog-leg, minus the weight on bit.

Jan 1, 1967

Discussion of the paper of G. K. Burgess and J. J. Crowe, presented at the New York Meeting, October, 1913, and printed in Bulletin No. 82, October, 1913, pp. 2537 to 2591. HENRY M. Howe, New York, N. Y. :-I think we can hardly rate the importance of the entry of the Bureau of Standards into our field. There is no body in the world that is better fitted to undertake this work than that Bureau, and it is work which really calls for the aid of some national organization. The skill and care with which this work has been done speaks for itself. It is very striking that within a very few months the distinguished English investigator, Professor Carpenter, of whom I spoke before, thought that he had disproved the existence of beta iron by proving that the A2 retardation which Professor Burgess has now demonstrated did not occur. Dr. Burgess's demonstration of the existence of. this retardation makes the existence of beta iron very probable, in my opinion. Osmond used to call beta iron " decipuum." You knew of its existence as you know of the existence of certain planets, only by the perturbation which it caused. Certain phenomena could not be explained, except by assuming the existence of a third allotropic form, beta iron. The evidence that you got was always evasive and susceptible of other explanations, except that which we have to-day, which it seems to me is not capable of other explanation. Professor Carpenter proceeded in the same way that Dr. Burgess has, by taking the heating and cooling curves of exceedingly pure iron, and thought that he had shown that there was no thermal change, no absorption or evolution of heat at the supposed A2 point, and hence that the A2 point did not exist. This he did by a piece of reasoning which I think seems to most of us rather surprising. That is to say, if of ten witnesses, three have seen a thing and seven have not, the evidence of the seven who have not is set aside, and that of the three who have seen stands. In Dr. Carpenter's own experiments under certain conditions he found the A2 change, the heat evolution., under certain others he did not. That is like the three witnesses who saw and the seven who did not see. You can arrange your test so that this change will not become visible or so that it is masked. But though an existent change can be masked a non-existent one cannot be shown. So that the reasoning seemed to me wholly fallacious.

Jan 12, 1913

By H. Larson, J. Chipman

The ferrous and ferric oxide concentrations of slags, expressed as j = Fe+++/(Fe+++ + Fe++), have been established through gas-slag equilibrium at 1550°C in a range of oxygen pressure of 10-I to 10-9 equilibriumatm. The value of j is increased by basic additions (BaO, CaO, MgO, MnO) and decreased by acidic oxides (SiO2 and TiO2). Oxygen pressure is shown graphically as a function of composition for slags which are analogous to those at the slag-gas interface of the open hearth furnace. THE progress which has been made in recent years in understanding the chemistry of metallurgical slags has been based largely on studies of slag-metal and slag-gas equilibria. There is a considerable body of knowledge which is applicable to reactions occurring at the slag-metal interface in open hearth steelmaking. There is little information concerning reactions of the slag with the furnace atmosphere and hence little basis for an understanding of the transfer of oxygen, sulphur, or hydrogen between gas and slag. The oxygen pressure of the open hearth atmosphere is normally of the order of 10-1 to 10-3 atm which differs by several orders of magnitude from that of about 10" atm at the slag-metal interface. The chemical properties of the slag, for example, the ratio of ferric to ferrous iron and the ability of the slag to hold sulphur in solution, are greatly affected by changes in oxygen pressure. This investigation was undertaken to enlarge our knowledge of the effect of oxygen Pressure on steel-making slags. Using air or controlled mixtures of CO a CO2 a range of oxygen Pressures from 10.' to 10.' was covered. Review of the Literature There are only a few references in the literature which pertain directly to this investigation. The most important is that of Darken and Gurry1,2 on the system iron-oxygen. This work included the determination of the phase diagram of the system and also a study of the field of homogeneous melts and their oxygen pressures. Their apparatus and procedure were very similar to that used in this study. Iron oxide was melted in a platinum crucible under an atmosphere of CO2:CO, CO2:H2, H2O, CO2, air or O2 depending upon the partial pressure of oxygen desired. After equilibrium was reached, the sample was quenched and analyzed for ferrous and ferric oxide. By appropriate calculations these authors were able to determine the oxygen and iron activities in the various slags, heats of formation of the oxides of iron, and heats of solution of iron and oxygen in the liquid slags. In a subsequent paper' the same authors made a less thorough investigation of the effects of additions of lime and manganese oxide on the composition of iron oxide melts. Only a few experiments were made and those in a narrower range of temperature and oxygen pressure. Darken' has investigated the fusion temperature of iron oxide in contact with silica under various atmospheres. He found that the temperature changes from 1120° to 1447°C as the gas composition changes from CO2/CO equal to 20.8 to pure oxygen. A comprehensive paper by White" predates the work of Darken and Gurry. The decomposition of ferric oxide into oxygen and lower oxides of iron was studied from 1000° to 1650°C and under oxygen pressures from 2 to 76 cm of mercury. The effect of

Jan 1, 1954

By R. R. Nash, W. F. Sheely, E. D. Levine

ThiS note reports on the variation with temperature of critical stress for basal slip of binary solid-solution single crystals of indium and of thorium in magnesium. PROCEDURE Alloy single crystal spheres were acid machined to 3/8-in. diam cylinders with the basal planes of the crystals normal to the cylinder axis and then annealed at 810°K. Stress was applied parallel to the slip system, (0001) [1120]. Experimental details will be presented in another paper.' Two nearly equivalent' techniques of stressing were used. Stress on the magnesium-indium alloy crystals was increased by 1 g per sq mm at 1-min intervals, and the critical flow stress was defined as the lowest stress to pro-

Jan 1, 1960

By N. E. Rogen, N. J. Grant

AGE-hardening in nickel-chromium-titanium-aluminum alloys in the composition range characterized by the Nimonic alloys, is dependent upon the precipitation of the Ni3(AI,Ti) (y') phase.1 This phase is found to precipitate at about 700°C.1 Ni,Al is a face-centered-cubic ordered structure with a lattice parameter of 3.560 A. The atomic configuration is such that the aluminum atoms occupy the cube corners and nickel occupies the cube faces with titanium substituting for the aluminum preferentially. A maximum of three out of every five aluminum atoms can be replaced by titanium atoms in the -y 'phase.' When the solubility of the y'-phase is exceeded for titanium the T(Ni,Ti) phase is formed. The T-phase is an ordered close-packed hexagonal intermetallic structure which shows little solubility for the other elements in these alloys. The lattice parameter for T-phase is a - 2.5454 kr and c = 8.2900 kx units."

Jan 1, 1959

By AIME AIME

THE papers on geophysics were roughly divided into two groups*, those presented Monday morning being of a more technical and theoretical nature, whereas the afternoon session was principally taken up with discussions of a predominantly geological flavor. Thus it was made possible for those of a mathematical turn of mind to indulge their penchant for formula and differentials before lunch, leaving the field comparatively free, after lunch, for the geologists to learn of practical applications. The advantage of this classification is evident, and it is to be hoped that in some future meetings it will be possible to hold joint sessions of the geophysicists and mining geologists, to consider the overlap of the two fields.

Jan 1, 1931

By A. M. Skov, L. F. Elkins

Inclusion of anisotropic permeability in mathematical analysis of pressure transients observed during development of the huge Spraberry field indicates a major fracture trend which is in good agreement with that observed by fluid-injection tests spread over a 12- by 17-mile area. Delineation of this trend is important in selecting a pattern of injection for the pending large-scale water flooding in this field. Determination of reservoir parameters yielding best agreement between calculated pressures and observed reservoir pressures in newly completed wells was made using an IBM 650 computer. INTRODUCTION The Spraberry field covering 400,000 acres is a tight sand of less than 1-md permeability cut by an extensive system of vertical fractures. Primary recovery dominated by capillary retention of oil in the fractured sand matrix blocks is less than 10 per cent of oil in place. Strong forces of capillary imbibition of water into the sand, coupled with water flow under dynamic pressure gradient, indicate considerable increase in oil recovery can be achieved through water flooding. Best results will occur if the pattern of water injection is selected to force the water flow across the grain of the major fracture system. Existence of an oriented vertical fracture system in the Spraberry, observed first in cores, was highlighted more recently by the 144-fold contrast in permeability along and at right angles to the major fracture trend required to match relative water breakthrough times in Humble Oil & Refining Co.'s waterflood test there. Spraberry operators since have conducted two gas-injection tracer tests for further areal confirmation of the fracture trend. Re-analysis of early reservoir pressure transients for evidence of anisotropic permeability has permitted many more local determinations of major fracture trend without resort to further field tests. This paper is limited to updating analysis of reservoir pressure transients to include anisotropic permeability as a test for orientation of the major fracture trend in the Spraberry. The reader is referred to Refs. 1 and 2 for information about general Spraberry reservoir performance and to Refs. 3 and 4 for information about significance of fracture orientation in selection of the injection-well pattern for water flooding the Spraberry. RESERVOIR PRESSURE DATA—DRIVER AREA During early development of the Spraberry Driver area, Sohio Petroleum Co. made the extra effort to measure the initial pressure in each of the 71 wells in a 5-mile-long area immediately after completion. Progressively greater reductions in pressure ranging up to 400 psi were observed throughout the six-month development period. Detailed data are presented in Ref. 1. Since the reservoir oil was undersaturated some 300 psi initially, early reservoir performance involving 55 new well pressures is subject to analysis as flow of a single compressible fluid in a porous media. Assumption of uniform permeability in all directions yielded good agreement between calculated pressures and observed pressures of these wells in the earlier study,' but subsequent, additional, mathematical development to include anisotropic permeability in the transient pressure considerations and present availability of electronic computers to perform the much more extensive arithmetical calculations now yield even better agreement. The previous analysis, assuming uniform permeability, consisted essentially of calculating pressure reduction expanding circularly around each producing well and summing these effects at the time and location of each newly completed well for comparison with the measured pressure reduction. Permeability, effective fluid and rock compressibility, and permeability X thickness were varied until the best match with measured pressures was obtained. The present analysis, assuming anisotropic

By Donald T. Hawkins, Ralph Hultgren

The lorsion effusion method has been used to measure the vapor pressure of lead over pure lead and eight Pb-Sn alloys ranging from 9.1 to 87.9 at. pct Pb in the temperature range 950° to 1125°K. The resulting ?H°y 298 = 46,630 ± 200 cal per g-atow for pure lead is in excellent agreement with previous work. Deriued ?Gph values for the alloys were smoothed and correlated with previous heat of formation data to obtain entropies for the liquid alloys. values for the tin component were calculated by Gibbs-Duhem integmtion. Surfhce depletion of these liquid alloys was found to be absent, as shown by the fact that the measured pressure remained substantially constant with time in contrast with previous measurements on iron-rich solid Fe-Mn alloys. The activities and Gibbs (free) energies of the liquid Pb-Sn system are not well known although the heats of formation have been accurately determined by K1eppa.l Vapor pressure determinations of the activity of lead by Voronin and Evseev2 disagree with those of Predel.3 Elliott and chipman4 measured activities by the electromotive -force technique in the ternary Pb-Sn-Cd system. From the resulting values of the activity of cadmium, they were able to calculate the activities of lead and tin for the binary Pb-Sn system at the compositions xsn = 0.33 and 0.67. Atarashiya, Uta, Shimoji, and Niwa5 determined the activity of tin from Hz-H2O equilibrium measurements, but their results are subject to question due to uncertainty in the final state of their samples. To resolve these differences, measurements of the activity of lead were made using a torsion-effusion apparatus. Among other advantages, this apparatus rapidly detects errors caused by surface depletion, which tends to reduce the apparent vapor pressure of the more volatile component. If the measured torques remain nearly constant with time, only bulk depletion is occurring. This contrasts with the rapid decrease in torque found in solid Fe-Mn alloys at high temperatures and low manganese contents.6 EXPERIMENTAL 99.999+ pct Pb was obtained from the American Smelting and Refining Co. and 99.999 pct Sn from Vulcan Detinning Co. Eight Pb-Sn alloys were prepared by melting together weighed amounts of the pure metals in evacuated Pyrex tubes and quenching the melts in water. Loss of weight in preparation was less than 0.02 pct in all cases. The effusion cells were made from high-purity, nonporous graphite. Graphite was chosen because of its resistance to reaction with lead and tin and because it can be accurately machined with precision orifices. Two cells were used with overall dimensions as shown in Fig. 1. The orifices of cells 1 and 2 were, respectively, 1 and 1.5 mm in diam.

Jan 1, 1968

By Frank C. Smith

THE following article covers the history of a metallurgical campaign, commenced in March, 1905, at the mines of the Socorro Gold Co., in the so-called desert region of Yuma county, Arizona. The results obtained were simply a function of necessity, as will be seen from the description of the local economic conditions and the character of the ores treated. The mines and mill of the Socorro Gold Co. are located near the small village of Harrisburg, about 60 miles from Congress Junction, Arizona, which, at the time this work was undertaken, was the nearest railroad station, and from which all supplies were brought by wagon through the desert, at a cost varying from $10 to $15 per ton in addition to the railroad freights. Wood, the only available fuel, cost $7 per cord. Water for all purposes was pumped to the plant from a well in the valley about 4 miles away. Under the Arizona law, a working-shift is 8 hr. Wages were $6 per day for foremen and mill-men, $4 per day for blacksmiths and engineers, $3.50 per day for miners, and $3 per day for shovelers and trammers. The ore consisted of quartz, in which, above the 250-ft. level, the iron-minerals were largely oxidized and some free gold was visible; below that level few traces of oxidation occurred, and pyrite constituted the principal mineralizer in the quartz, together with occasional pockets of galena and a few eccentric specks of covellite. The 20-stamp mill was equipped with plates for amalgamation, and three Standard tables for concentration. The tails from the tables were elevated by a centrifugal pump to a launder, by which they were conveyed to a 60-ton cyanide-mill for further treatment. The cyanide-mill was erected at so great a distance from the stamp-mill that a separate crew of workers and a separate power-plant were necessary. No arrangement had been made for the treatment of the concen-

Jan 1, 1907

By Archer E. Wheeler, Milo W. Krejci

There are two general methods in use for the production of metallic copper from matte which are worthy of consideration : (1) the Welsh blister process, and (2) the converter process.' As practically all of the copper produced to-day is made in converters, we will give a brief outline of that process before proceeding with the special subject of this paper. Matte may be roughly defined as a mixture of the sulphides of copper, iron, nickel, silver, etc. In the converter process this is blown up to metallic copper in a modified type of Bessemer converter. The conversion of matte consists mainly in, (1) the removal of sulphur in the form of SO2, and (2) the slagging of the iron. With this brief statement we come to the two subdivisions of the process of converting mattes: Converting with acid linings. Converting with basic linings. Converting with Acid Lininys, This is carried out by lining the converter with siliceous rock or ore, which performs two functions: It protects the iron shell of the converter from the molten charge, and it furnishes the silica for combining with the iron as it is oxidized from the matte, to form a ferrous silicate. It follows from the second of these functions that this siliceous lining must be replaced from time to time, and in practice it has been necessary to reline converters every 8 to 40 hr., this time varying in different plants and even with different linings in the same plant, the life of a lining depending upon the grade of the matte treated, and upon the composition, the thickness, the tamping, and the drying of the lining.

Jan 1, 1914

By N. F. Schulz, H. A. Lex

Representative samples of typical manganiferous iron ores from the Cuyuna Range, Minn., were reduced to the metallic iron state at temperatures just short of fusion with an excess of coke in the manner prescribed by the R-N Direct Reduction Process. The magnetic separation characteristics of the reduced ores were determined at several grinds by means of the Davis magnetic tube concentrator. The efficiency of metallic iron concentration by magnetic separation was a direct function of the degree of metallization of the ore sample and of the degree of liberation at-tained in grinding. Some improvement of liberation characteristics was observed if a small amount of sodium chloride was present in the ore during reduction. Despite the extremely fine-grained structure of the crude ores, iron concentrates containing more than 90% Fe at iron unit recoveries of 90% or more were obtained from well-metallized samples of three of the four ores tested. The rejection of manganese to the tailings corresponding to such separations varied from 80% to 95%. The manganiferous iron ores of the Cuyuna Range in Minnesota constitute a major potential source of manganese in the United States provided that a technically and economically feasible process can be devised for its recovery. The iron and manganese of these ores occur chiefly as oxides or carbonates in the form of very small, irregular, discrete grains embedded in a matrix of quartz or other siliceous gangue. The present investigation was undertaken as a sequel to an earlier one conducted jointly by the U.S. Bureau of Mines and the R-N Corp. Those results indicated that the R-N Direct Reduction Process might be a means for recovering both a metallic iron concentrate and a marketable manganese by-product from Cuyuna manganiferous iron ores.' The R-N Process is one of many proposed schemes for the treatment of crude iron ores involving the di- rect reduction of the iron content to metallic iron followed by physical extraction of the iron. In general, it consists of the following stepsz2 1) Iron oxide in crushed natural ores or iron concentrates is about 95% reduced to metallic iron at elevated temperatures but without fusion in a rotary kiln in the presence of a solid carbonaceous fuel (usually coke), limestone, and combustible gases. 2) The kiln product, consisting of metallized ore, excess coke, lime, and coke ash is cooled. The excess coke is recovered and recycled to the kiln feed. 3) The metallized ore is ground for liberation and magnetically separated to yield a metallic iron concentrate. 4) The metallic iron concentrate is agglomerated by a briquetting process. The reduction kiln temperatures must be high enough for the desirable chemical reactions to proceed at practical rates without causing fusion of any of the ore constituents. The time of exposure of the ore to the reducing conditions must be ample for 90% to 95% metallization of the iron oxides present. If more than 95% of the iron is metallized, however, difficulties may arise in the briquetting step, presumably because of accompanying higher carbon content of the metallic iron. Although not always necessary, powdered limestone or dolomite may be added at some time during reduction to aid in eliminating sulfur and phosphorus from the final product.3,4 Other additives, notably sodium chloride, when present during reduction, result in improved liberation characteristics of the metallic iron from certain reduced ores.'v6 Under the reducing conditions normally employed, P(co + H2)= 1 atmosphere, and 1830' to 2150°F (1000° to 1170°C), the R-N Process is claimed to be adaptable to a wide variety of low, medium, and high grade iron and manganiferous iron ores. The manganese oxides and carbonates are reduced mostly to nonmagnetic MnO which is rejected to the nonmagnetic tailings. Manganese-bearing pyroxenes of the original ore, however, may be rejected poorly, if at all, apparently because these minerals occur within the iron lattice or are entrapped in the metal particles.7 The investigation was limited to studies of the Cuyuna ores listed in Table I, which were reduced to the metallic iron state under various conditions

Jan 1, 1969

By R. G. Weavind, R. S. Young, I. Wolf

ONE of the most important fields of investigation at the Diamond Research Laboratory in Johannesburg is concerned with improvements in metallurgical practices for the diamond mining companies, with particular reference to increased recoveries of the smaller industrial stones. Considerable work has been done on the possible application of flotation processes to the diamond industry. From the viewpoint of recovery processes, diamonds in their natural state may be grouped into two classes, the water-repellent diamonds, which adhere to a grease surface, and the water-avid diamonds, which, because of their wettability, will not adhere to a grease surface and must be recovered by means other than the grease tables used for water-repellent diamonds. Experiments in the flotation of small diamonds from both kimberlite and alluvial deposits indicate the following conclusions: Water-repellent diamonds: Satisfactory flotation of —16 mesh diamonds, which are naturally water-repellent, may be accomplished using either Aero-float 25 together with cresylic acid, or Du Pont B23 as frother together with kerosine as auxiliary oily conditioner or froth stiffener. The quantities of reagents required are of the order of 0.15 lb per ton Aerofloat and 0.18 lb per ton cresylic acid. The use of acid circuits is detrimental, and for best results a pH between 7 and 9 should be maintained. R. G. WEAVIND and I. WOLF are with the Diamond Research Laboratory, Johannesburg, South Africa, and R. S. YOUNG, Member AIME, is Director of Research, Diamond Research Laboratory. TN 76B. Manuscript, March 23, 1951. A flotation period of 5 to 10 min is necessary to insure that all floatable diamonds are removed. Diamonds larger than 16 mesh cannot be recovered satisfactorily by flotation. Xanthates do not act as collectors for diamonds, and this is probably associated with their inability to impart a water-repellent surface to this mineral. Water-repellent diamonds smaller than 28 mesh can be floated quite well by the addition of a frother alone, such as pine oil or Du Pont B23. Water-avid diamonds: Partial flotation of the smaller sizes of wettable diamonds can be achieved by preconditioning with fatty acid soaps, cationic amines, and similar reagents, which will impart a water-repellent film to diamonds. Washing to remove excess reagent, followed by flotation, will result in a fair recovery, but the latter is much lower than for water-repellent diamonds. Crushed boart: Recovery of crushed boart from the waste products of industrial uses is best accomplished by first conditioning the diamonds present in the mixture with fatty acids, cationic amines, etc., removing the conditioning agent by washing, and floating in a cell of the pneumatic type. Flotation reagents found to be most suitable are Du Pont B23, and Aerofloat 25 together with cresylic acid. The optimum quantities are 1.2 g Du Pont B23, and 0.55 g Aerofloat plus 1.4 g cresylic acid, per liter of pulp in the cell. A solids-to-water ratio of 1 to 4 is found to be the most suitable, and alkaline circuits are necessary for best results. Diamonds larger than 28 mesh are not recovered satisfactorily by this procedure, but for finer sizes flotation offers an excellent procedure for the reclamation of this strategic industrial material.

Jan 1, 1952

By Akio Suzuki, P. G. Wahlbeck

AS a part of a study of the vaporization of transition metal-chalcogen systems, the vaporization reactions for the Ti-Se system have been studied. In order to establish vaporization reactions it is important to determine the identity of vapor species in equilibrium with the condensed phases. In some cases, it is possible to deduce the identity of vapor species through observations of composition change of the condensed phase with which the vapor is in equilibrium. Determination of vapor species in equilibrium with condensed phases should precede vapor-pressure measurements and is necessary for proper thermodynamic analysis of vapor-pressure data. Bear and McTag-gart' reported that vacuum heating ot TiSea at 950°C produced a residue with a composition of 1.7 Se/Ti atomic ratio units. Analyses of condensed phases existing for the Ti-Se system have been performed by Bernusset,2"4 Gron-vold and Langmyhr,5 Hahn and Ness,' and Ehrlich.~ Results and conclusions of two types of experiments are described herein: 1) experiments where samples of known composition were vaporized followed by chemical analysis of residues and 2) experiments where the vapor species were identified by means of a mass spectrometer. Experimental Section. Sarnple Preparation. Samples of TiSe2 were prepared in a sealed, evacuated quartz ampule by heating to 1000°C stoichiometric amounts of selenium of 99.999+ pct purity obtained from the American Smelting and Refining Co. and titanium of 99.2 pct purity obtained from A. D. Mackay, Inc. After heating, the sample was ground and reheated to insure homogeneity. Samples containing less selenium than TiSez were prepared by mixing amounts of titanium powder and TiSez appropriate for the desired composition; the titanium and TiSez mixture was heated in the same manner as described for TiSe2. Analyses of titanium selenide samples contained in quartz crucibles were performed by gravimetric oxidation in oxygen at 800°C; the products of the oxidation were solid TiOz and gaseous Se02. The mass of the original sample and the mass of TiOn determined the Se/Ti atomic ratio. The sample of TiSen used in these experiments had a composition of 2.04 Se/Ti atomic ratio units. The compositions for all samples reported were analyzed by this method. Va/!orization Experiments. Samples of titanium selenides were vaporized in tungsten Knudsen crucibles. Some vaporization experiments were carried out in glass vacuum lines followed by chemical analyses of residues, and some vaporization experiments were performed with a Bendjx mass spectrometer as described previously.8

Jan 1, 1967

By G. G. Gunther, C. L. Boeke

DISCUSSION I. M. Symonds, (Cia. Minera de Penoles, Monterrey, N. L., Mexico)—Messrs. Boeke and Gunther have written most interesting papers describing their zinc de-leading operations. Mr. Gunther was kind enough to show me his operation last fall. Aside from the excellent results, I was most impressed by the ease of control. I had expected a difficult operation requiring careful control and supervision, but found one requiring little attention. The only disappointing fact of the separation is the poor copper recovery in the concentrate of the delead-ing float. The final zinc concentrate still has about 3 pct chalcopyrite, assuming the copper is chalcopyrite, and adversely affects the zinc grade. If the copper mineral is free, the poor recovery is probably due to the high cyanide concentration. Fortunately, about 75 pct of the copper is recovered before the pulp goes to the zinc circuit. Mr. Gunther's remarks about proper cyanide to zinc sulphate ratios cannot be overemphasized. Although our experience has been confined mostly to the conventional lead-zinc separation, we have found these ratios most important, and more important in the mill than in the laboratory. The laboratory appears to give optimum results over a wider range of reagent control than the mill, especially in regard to the effect of cyanide. In handling relatively high grade ores in the mill we usually find that ratios of cyanide to zinc sulphate of 1 to 10 or 20 or higher work best. Where there is a substantial amount of chalcopyrite present it has been noted that cyanide in the range of 0.02 to 0.10 lb per ton of ore is often beneficial in zinc rejection and possibly in copper recovery in the lead concentrate, while larger amounts, say 0.20 to 0.25 lb per ton, will float more zinc and cause a serious rejection of chalcopyrite. On an ore with 15 to 20 pct zinc content we have had to use 0.8 to 1.2 pounds of zinc sulphate per ton of ore with the above cyanide to obtain optimum results. Some time ago we made a laboratory study following Parral and Santa Barbara practice on an ore which had never a very satisfactory rejection of zinc in the lead concentrate. The results were not encouraging and a mill test was not run. Since then the study has been reopened using in the laboratory fresh zinc concentrate from the mill instead of one made in the laboratory. A reasonably clean lead float from the zinc concentrate was obtained. It has been checked several times and each time the zinc concentrate made in the mill responds and the one made in the labora-

Jan 1, 1953

By G. G. Gunther, C. L. Boeke

DISCUSSION I. M. Symonds, (Cia. Minera de Penoles, Monterrey, N. L., Mexico)—Messrs. Boeke and Gunther have written most interesting papers describing their zinc de-leading operations. Mr. Gunther was kind enough to show me his operation last fall. Aside from the excellent results, I was most impressed by the ease of control. I had expected a difficult operation requiring careful control and supervision, but found one requiring little attention. The only disappointing fact of the separation is the poor copper recovery in the concentrate of the delead-ing float. The final zinc concentrate still has about 3 pct chalcopyrite, assuming the copper is chalcopyrite, and adversely affects the zinc grade. If the copper mineral is free, the poor recovery is probably due to the high cyanide concentration. Fortunately, about 75 pct of the copper is recovered before the pulp goes to the zinc circuit. Mr. Gunther's remarks about proper cyanide to zinc sulphate ratios cannot be overemphasized. Although our experience has been confined mostly to the conventional lead-zinc separation, we have found these ratios most important, and more important in the mill than in the laboratory. The laboratory appears to give optimum results over a wider range of reagent control than the mill, especially in regard to the effect of cyanide. In handling relatively high grade ores in the mill we usually find that ratios of cyanide to zinc sulphate of 1 to 10 or 20 or higher work best. Where there is a substantial amount of chalcopyrite present it has been noted that cyanide in the range of 0.02 to 0.10 lb per ton of ore is often beneficial in zinc rejection and possibly in copper recovery in the lead concentrate, while larger amounts, say 0.20 to 0.25 lb per ton, will float more zinc and cause a serious rejection of chalcopyrite. On an ore with 15 to 20 pct zinc content we have had to use 0.8 to 1.2 pounds of zinc sulphate per ton of ore with the above cyanide to obtain optimum results. Some time ago we made a laboratory study following Parral and Santa Barbara practice on an ore which had never a very satisfactory rejection of zinc in the lead concentrate. The results were not encouraging and a mill test was not run. Since then the study has been reopened using in the laboratory fresh zinc concentrate from the mill instead of one made in the laboratory. A reasonably clean lead float from the zinc concentrate was obtained. It has been checked several times and each time the zinc concentrate made in the mill responds and the one made in the labora-

Jan 1, 1953

By B. N. Bose, M. F. Hawk

SINCE Davenport and Bain' introduced the isothermal transformation technique for the study of austenite decomposition in steels, a new field of investigation has opened up. Extensive research has been carried out on many different steels, but relatively little work has been done on eutectoid transformations in analogous alloy systems. The researches of Smith and Lindlief,² Mack,³ and Klier and Grymko²0 on the beta-phase transformation in copper-aluminum alloys, of Hibbard, Eichelrnan, and Saunders4 and Smith5 on the kappa-phase transformation in copper-silicon alloys, of Chaudron and Forester6 on the decomposition of "FeO," and of Wasserman7 on similarities between the iron-carbon, copper-aluminum, copper-tin, and copper-beryllium systems essentially comprise the field. The iron-nitrogen system, in view of its remarkable similarity to the iron-carbon system, is particularly attractive for the study of eutectoid decomposition. The present investigation is concerned with the study of isothermal transformation, proceeding by the familiar nucleation and growth processes, and of martensitic transformation characteristics of pure iron-nitrogen alloys. The kinetics of transformation and the morphology of the transformation products have been investigated, for these must be the factors determining the properties and behavior of the final product. The Iron-Nitrogen System he binary iron-nitrogen phase diagram has been a matter of considerable disagreement among vari01.1s investigators. However, the phase diagram according to Eisenhut and Kaupp8 and Lehrer10 is now considered essentially correct as reproduced in fig. 1. The important values, 2.35 pct nitrogen and 591°C, for the co-ordinates of the eutectoid point (obtained from this diagram and used in the re- search to be described) were confirmed in a concurrent study of Paranjpe, Cohen, Bever and Floe." The eutectoid decomposition involves the transformation of the ? face-centered cubic interstitial solid solution of nitrogen in iron to the a body-centered cubic interstitial solid solution of nitrogen in iron and the ?' nitride of iron. This nitride is essentially the compound Fe,N; it also possesses a face-centered cubic lattice but a considerably larger one than the ?; the nitrogen atoms in ?' are arranged in an ordered way in the centers of the unit cubes.8,10,11 A martensitic structure has also been reported8,12 in iron-nitrogen alloys and was studied in the research to be described here. Materials and Methods The specimens used in this investigation were prepared by nitriding "pure" iron. This iron was supplied by the Westinghouse Research Laboratories and is the product bearing their trade name "Puron"; it contains about 0.04 wt pct total impurities, the major portion of which is oxygen. Specimens were ribbons several inches long, a tenth of an inch wide, and 0.125 mm thick; this was the

Jan 1, 1951

By R. Lagneborg, R. Gullberg

An X-ray method for determinig volume fractions of phases in textured materials has been developed. The method involves measurements of the integrated intensities of reflections of each phase for one single orientation of the sample. The method was checked by evaluating the phase contents in samples from two stainless Cr-Ni steels containing austenite and ferrite in known amounts. In the present case measurements of about five reflections from each phase were required. The agreement between calculated and known volume fractions was found to be very close. AN X-ray diffraction method is often employed for determining the amounts of two or more phases in a material. The details of the method have been described at several instances.'" In short, the method is based upon the fact that the integrated intensity of a reflection is directly proportional to the volume fraction of the phase considered. In principle, the method only requires the measurement of the intensity of one reflection for each phase. The most severe shortcoming with this method is that it disregards influences from preferred orientation in the material. In a diffractometer, where this type of analysis is most conveniently carried out, the geometry is such that the diffracting planes for a specific Bragg peak are all parallel to the surface of the specimen. This implies that it must be required that the occurrence of the diffracting planes parallel to the specimen surface must be as frequent as for any arbitrarily oriented physical plane of the sample. This requirement will generally only be fulfilled for a material free of texture. Since all materials in reality always exhibit a preferred orientation to some extent. the deficiency of the method is quite serious. In cold-deformed material the texture is appreciable, but also annealed material will in many cases display a considerable texture. The problem of quantitative phase analysis in textured material is one of obtaining the integrated intensity averaged over all orientations of the specimen with respect to the X-ray beam. Lopata and ~ula~ have shown that this can be accomplished by integration of intensities over the whole pole figure, or by random rotation of the specimen in the X-ray beam, or by a combination of both. Hence, in this method the average integrated intensity for a specific reflection is obtained by directly determining the intensity for a sufficient number of physical orientations of the sample. However, since an excess of diffracting planes in a certain surface plane necessarily must be accompanied by a deficiency of another type of diffracting plane, it appears to be possible to obtain the correct average intensity for a specific diffracting plane by performing an appropriate averaging of intensities belonging to a large number of diffraction planes of different hkl when all intensities have been produced from one single orientation of the specimen surface. In the present work such a method has been attempted and tested experimentally for two stainless Cr-Ni steels containing austenite and ferrite. 1) THEORY The expression for the integrated intensity of a Bragg reflection diffracted from a phase in a polycrys-talline sample in a diffractometer is: where C is a constant only dependent on the incident X-ray power and the diffractometer geometry, v the volume of the unit cell, F the structure factor, m multiplicity of the diffracting plane, L Lorentz factor, P polarization factor, e-2 temperature factor, p average linear absorption coefficient of the irradiated vO1umej and V volume fraction of the phase 'Onsidered. Hence, the factor R in the abbreviated form of Eq. [I] can be calculated and depends only on 0 and the diffracting plane {hkl}. For an alloy containing two phases, a and y, we can write

Jan 1, 1967

By George W. Mansfield

My plan in this paper is, first, to prove three general points, and then to take up the specific applications of the electric motor to nining work. The three poinb are: 1. The electric system is the simplest method known for transmitting and distributing any amount of energy from one locality to another, irrespective of the intervening distance. 2. The electric system with its applications is not in its infancy.

Jan 1, 1888

By L. R. Mabson, F. M. Russell

INRODUCTION Roan Consolidated Mines Limited (RCM) operates five underground mines - Mufulira, Luanshya, Baluba, Chambeshi and Chibuluma (figure 1) . Associated metallurgical plants provide for the operations of milling, smelting two refineries for copper and a cobalt plant. Primarily a producer of high quality copper (242,000 tonnes during 1980) the Company is also the world's second largest producer of cobalt metal. RCM's remaining ore reserves at 31st March 1980 were 275 million tonnes at 2.84% copper. Monthly ore production is in excess of 1.2 million tonnes. Sublevel open stoping was the choice of mining method for the first underground operations on the Copperbelt for ore with dips steeper than 30 degrees. This was for use at the Roan Antelope mine, subsequently to be called Luanshya mine. The sublevel open stoping system was planned based on the methods used in many of the iron mines of Michigan and New York and in the copper mines of Tennessee. Peterson (Ref. 1) gave the following reasons for employing sublevel stoping, reasons which are still valid today: (1) the working place could always be barred and made safe, and the sublevel exit was always at hand; (2) the working conditions were similar day by day and drilling operations were repetitive; (3) pillar spacing can be varied as conditions demand; and (4) stoping operations could be shut down completely or opened up to full capacity at short notice, without affecting grade or causing wastage of reserves. Such was the success of the method that it was adopted as the basic mining method at all the RCM mines in their initial stages. Although cut and fill, block caving, and sub- level caving methods have been used, sublevel open stoping in its many variants still accounts for nearly 90% of total ore production in the Company. The following descriptions outline some of the applications of sublevel open stoping within RCM. LUANSHYA Geology There are two main ore deposits at Luanshya: the Roan (Luanshya Mining Area), in which mining began in 1930, and Baluba, in which mining production started in 1973 (figure 2). Both orebodies occur in synclinal and variably folded basins. These basins are underlain and completely surrounded by much older schists and granites. The ore formation, an argillite, lies near the base of the sediments and is underlain by conglomerates, quartzites and arkoses. Copper mineralisation is mainly found in two well defined zones, separated by a varying thickness of pyrite mineralisation. In the eastern part of the Roan deposit only the upper orebody is present, but west of 18 shaft and at Baluba the lower orebody predominates. Locally the subjacent quartzites of the footwall formation are also mineralised with copper. The copper mineralisation is found princi- pally as disseminated sulphides, mainly chalcocite, bornite and chalcopyrite. Near the surface the sulphides have been changed to oxides. At Baluba the cobalt mineral carrollite is found with the sulphides. Mining methods Sublevel open stoping is the basic mining method. In its standard form this method is best suited to steeply inclined orebodies, with simple structures and with a strong foot- wall and hangingwall. In recent years, as more complex folding and flatter dipping orebodies have been encountered, considerable variations have been introduced. Stope drilling is effected with drifters and extension steel.

Jan 1, 1981