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By D. D. Pollock

Many constitution diagrams do not indicate the limits oJ solid solubility of the silver-rich solid solutions below 200°C. Thermoelectric measurements were employed to determine this limit in the nieighborhood of room temperature. The appearance of a second phase causes a discontinuity to occur in the tkevtrroelectric power as a function of cornposition at constant temperature and pressure. This discontinuity was employed to determine the limits of the silver-rich terzinal solid solutions of the Ag-A l, Ag-As, Ag- Bi, Ag--Ge, Ag-In, Ag-Pb, Ag-Sb, and Ag-Sn systenls at 30°C. CONSIDERABLE work has been done on the constitution of binary alloys of silver. The available data have been compiled by Hansen1 and Elliott.2 However, many of the binary diagrams do not show the limits of solid solubility of the silver-rich solutions below about 200° C. This work was undertaken in an attempt to extend these limits to the neighborhood of room temperature . PREPARATION OF ALLOYS All of the alloys were made with silver containing less than 0.014 pct (by weight) of impurities. The materials were weighed out into 225-g heats and melted in a high-frequency induction furnace. The indium, tin, and antimony alloys were melted in A1203 crucibles, under a boric anhydride cover, and were poured into split graphite finger molds. The aluminum, germanium, arsenic, lead, and bismuth alloys were melted in machined graphite crucibles; they were also covered with boric anhydride and poured into split graphite finger molds. The $-in.-diam ingots were heated to 750°C and were forged and hot-rolled down to 0.1 by 0.1 in. The wires were pickled in a 25 pct HNO3-75 pct H2O solution to remove any oxygen-rich surfaces. The wires were then annealed at 550°C for 2 hr in a dissociated ammonia atmosphere. They were then furnace-cooled for 20 hr to room temperature in this atmosphere. The wires were cold-drawn to 0.0808 in. diam. The finished wires were again annealed at 550°C in the same manner as in the first anneal. Thermoelectric Power. The thermoelectric power of a single specimen of each alloy was determined against pure silver which contained a maximum impurity content of 0.014 pct by weight. The wire specimens were straightened and then cleaned with ethyl alcohol. They were then reannealed in the same way as the finished wires to assure that any residual stress would be at a minimum level. Previous work has shown that the presence of small amounts of stress has the effect of decreasing the thermoelectric power. The alloy specimen was soldered to the pure silver wire to form the measuring junction. A standard set of copper leads was then soldered to the reference junctions of the thermocouple. These junctions were maintained in separate dewar flasks which contained finely shaved melting ice during the test. The thermal electromotive forces of the thermocouples were measured at four temperatures between 15° and 45°C. A known source of electromotive force was balanced against the output of the thermocouple until a null balance was reached. The data were then expressed in terms of the thermoelectric power at 30°C. The results were then converted to absolute thermoelectric power, s303.3 These data have an average error of less than ±0.2 pct. RESULTS AND DISCUSSION All of the experimental data are given in Table 11. Since the electromotive forces of the binary alloys of silver were determined against the pure silver from which they were made, the resultant thermoelectric powers are only a function of the intentionally added binary elements at the constant test temperatures. This provides a direct measure of the effects of the alloying elements. The absolute thermoelectric power of an alloy of silver is given4 by:

Jan 1, 1968

By T. L. Joseph, G. Bitsianes

THE layered structure of partially reduced iron ore was described in a previous paper.' Reduction by hydrogen was found to take place at well-defined interfaces between layers of the solid phases. In the present investigation, a detailed study was made of the wiistite phase that had formed during the partial reduction of a cylindrical compact of chemically pure hematite. An unusually wide band of wiistite permitted a rather detailed study of this phase. The specimen was made from Baker's C.P. hematite in the form of a cylinder 1.5 cm in diameter and 1.8 cm long. A dense ore structure with about 6 pct porosity was attained by heating the specimen in air at 1100°C for 3 hr. To confine reduction to the top surface, a ceramic coating was applied to the bottom and sides of the cylindrical compact. The specimen was then partially reduced in hydrogen at 850°C and subjected to a coordinated sequence of macro-, micro-, and X-ray examinations. A section of the partially reduced cylinder is shown in the macrograph, Fig. 1. Four layers consisting of metallic iron, wustite, magnetite, and unreduced hematite are clearly shown. The effort to force reduction to proceed downward in topochemi-cal fashion was only partly successful, as some reduction occurred along one side and bottom of the cylinder. A rather wide layer of dark wustite phase had formed, however, and permitted sampling for X-ray studies as indicated. To supplement previous work and to study the wustite layer in more detail, ten separate layers were removed for X-ray examination. Broad and diffuse patterns were obtained with the as-filed powders, especially with those of iron and wiistite, and the condition indicated a cold-working and variable composition effect within the respective layers. This condition was corrected by annealing the entire series of powders at an appropriate temperature. For the annealing treatment, the ten powder samples were wrapped in silver foil, sealed under vacuum in small quartz tubes, and heated at 750°C for 16 hr. The specimens were then drastically quenched in cold water to preserve the annealed condition. These annealed specimens were X-rayed in turn and the compiled patterns are shown in Fig. 2. The standard patterns for iron and its oxides have been interjected at appropriate positions for purposes of comparison and phase identification. All of the patterns obtained were clearcut and concise so that positive identifications could be made for all of the phases. The outermost layers A, B, and C were composed almost entirely of iron with a small amount of wiistite being detectable at the X-ray limit of phase detection. Layer D from the iron-wustite interface showed both of these phases. The next four layers E, F, G, and H were all in the dark phase band which had been tentatively identified as wustite by the macroexamination, Fig. 1. The diffraction data with their single-phase patterns of wiistite for these layers checked the visual evidence. Continuing the X-ray analyses after layer H, the macrograph (Fig. 1) shows that layer I came largely from the magnetite zone but included some fringes of the wiistite-magnetite interface. The diffraction pattern for the sample confirmed this observation. Layer J came from the unreduced core of the specimen and its diffraction pattern indicated a preponderance of hematite phase. The reduction behavior of synthetic compacts has thus been found to be similar to natural dense iron ore. The previous results were supplemented with measurements of the diffraction films and calculations of the respective unit parameters. These X-ray data are summarized in Table I and offer some interesting correlations as to the compositions of the various phases undergoing reduction. The iron layers that were analyzed gave lattice parameters close to that of pure iron at 2.8664A. Evidently this iron was present in layers A through D as a pure phase with little or no oxygen dissolved in its lattice. With the wiistite layers an entirely different situation prevailed in that there was a definite and

Jan 1, 1955

By J. C. Fisher

Martensite transformations in steels and other alloys are characterized in part by the absence of composition changes during the growth of a new phase. Transformation occurs rapidly, and there is insufficient time for long range diffusion or partition of alloying elements to take place; martensite reactions in alloys thus are similar to phase transformations in single component systems. A fundamental understanding of martensite transformations in steels is impossible without knowledge of the free energy change upon transforming austenite (face centered cubic iron containing alloying elements) to ferrite (body centered cubic iron containing alloying elements) of the same chemical composition. The present paper assembles the best information available concerning the influence of temperature and composition on this free energy change. Most of the material has been taken from the work of Johansson,' Mehl and Wells,2 Zener3,4 and Smith;5 and indirectly, through these authors, from the work of Austin.6 In agreement with the generally accepted viewpoint, martensite is assumed to be an ordered solution of carbon in ferrite of the same composition as the parent austenite; only at high temperatures and low carbon concentrations is the carbon in ferrite distributed at random. The properties of the disordered solution are estimated by extrapolating the known properties of iron-carbon solid solutions into the range of supersaturation, and the free energy change associated with ordering is estimated from the theory developed by Zener. By incorporating Smith's recent thermodynamic measurements and Zener's theory of ordering, the present analysis modifies previous estimates of the free energy change associ- ated with martensite transformations. Consider a two component system consisting of a solvent A and a solute B. Let Na and Nb represent mol fractions of A and B respectively, let aa = raNa and ab = YbNb represent activities, and let superscripts 1 and 2 refer to phases 1 and 2. The partial molal free energies of A and B in phases 1 and 2 can be summarized as follows: free energy standard state Fa' - Fao1 = RT In an1 pure A' Fa2 - Fa2 = RT In aa2 pure A2 Fb1 - Fbo = RT In ab1 pure B Fs2 - FB2 = RT In aB2 pure B. The free energy of a gram atom of phase 1 is* AF1 = Na'Fa1 + Nb'Fb1 and that of phase 2 is AF2 = NA2FA2 + NB2Fb2. A martensite transformation from phase 1 to phase 2 requires Na1 = Na2 = Na and NB1 = NB2 = Nb, and the free energy change per gram atom accompanying transformation is AFi-2 = NA(Fa2 - Fa1) + Nb(Fb2 - Fb1) = NA[RT In (aA2/aA1) + AFa1?2] + Nb RT In (aB2/aB1) = Na[RT In (ra2/ra1) + AFa1?2] + Nb RT In (TaVTB1). [1] where yn2, yn1, yB2, yB1 are activity coefficients, and where Ma'+* is the free energy change upon transforming a gram atom of pure A from phase 1 to phase 2 at the temperature in question. For martensite transformations in plain carbon steels, A = iron (Fe), B = carbon (C), 1 = austenite (7). 2 = ferrite (a), and Eq 1 is AFr ?a= NFe[RT In (rf.a/rfer) + AFF.r?a] + TVc RT In (eca/rc1)- L2] Nothing is known concerning the values of yFea and yca for carbon concen- , trations in excess of 0.025 pct. However, the approximation rf.7 = 7f." = 1 cannot be appreciably in error for small carbon concentrations, and Eq 2 reduces to Afr-a = NfeFfer?a1 + NC RT In (rca/rcr)- [3] Johanssonl and Zenera have calculated MFfr?a from the specific heat measurements compiled by Austin.6* Their calculated values agree closely, and are summarized in Table 1. The activity coefficients relative to graphite for carbon dissolved in iron vary with temperature according to the relationships d In rcr/d(1/T) = AHcr-R dlnyca/d(l/T) = AHCa/R where AHc? and AHca are the heats of solution of graphite in y and a iron. Assuming the values of AH to be independent of carbon concentration and temperature, In rCr = AHcr/RT + I1 In rca = AHCa/RT + 12

Jan 1, 1950

By B M. H Sharp, R P. Hide, S P. Devine

Uncertainty and debate currently pervade the mining industry in New Zealand. The operational uncertainties, whether external (eg gold prices, the exchange rate), or internal (eg coal expansion difficulties), are large. In addition, many wider factors which influence mining are in a state of flux. State Coal Mines, the operating branch of the Mines Division of the Ministry of Energy I may be made a state corporation, with the remaining Mines Division functions being revamped. The agencies administering environmental legislation are to be restructured. Mining legislation amendments have been proposed and then dropped, and the area is now to be reviewed (The Press, 31 July 1985). Some mining licences have been withdrawn, and become the subject of heated debate in the community (The Press, 19 July 1985, and subsequent letters to the editor).

Jan 1, 1985

By G. F. Bolling

Single crystals of each metal were deformed at 77°K and heated at constant rates, variously in the range 0.125" to 4o°Kper min from 77" to -390oK, while being monitored in an X-ray diffractometer. Changes in diffraction-peak heights and line breadths were used to ascertain the temperature ranges of recrystalliza-tion. The results were subjected to the analysis of nicholas' in order to obtain the rate-controlling activation energies,Q. In this analysis no recourse to a separate and distinct nucleation stage is required and the results of studying recrystallization proved consistent with the hypothesis of a constant number of nuclei or equivalent hypotheses. The values Pb = 5.5 ± 0.5 keal per mole Zn ~ 7.5 Sn - 5 Bi - 9. 5 correspond for lead, zinc, and tin to activation energies obtained elsewhere for grain boundary migration, and for bismuth and lead to previous studies of re-crystallization by Barrett.6 This correlation allows the conclusions that interference from recovery was minimal and that the observed recrystallization rates in these pure metals are effectively governed by grain boundary migration. Good agreement was not found between the results of this kind of study in zone-refined aluminum and previous work; and supplementary isothermral experiments involving hardness tests and metallography did not resolve the discrepancy. Nevertheless, at least a range,Q = 11.5 ± 2 keal per mole, can be assigned to the activation energy for boundary migration in aluminum. An experimental study of one aspect of the recrystallization process is presented here for four metals of different crystal structure. The metals chosen for study were all zone-refined to reduce impurity effects, but the attendant high purity presented a difficulty. For any reasonably high driving force a "re-crystallization temperature", TR, is in the range of 0.25 T,, where T, is the absolute melting point, and study was therefore restricted to lower temperatures. An X-ray technique under constant heating-rate conditions adequate above 90°K was devised for the study; in consequence, a newer type of analysis following Nicholas1 had to be used to obtain quantitative information about activation energies. The standard methods of studying recrystallization have involved the comparable analyses of Johnson and Mehl2 and Avrami3 which are reviewed by Burke and Turnbull.* The general analysis4 which is applied only to isothermal studies using any of various investigative techniques states:

Jan 1, 1968

By Timothy W. Ellis

"This paper presents the basic theory of operation, physical chemistry and phase equilibria which allow the development of liquid-liquid extraction circuits based on metallic solvents. The incorporation of reduction and reduction/diffusion processes into the process scheme is discussed and a detailed description of several liquid-liquid extraction schemes are developed. A synopsis of experimental results obtained using this method to separate rare earth and other metal based materials will be given.IntroductionConcerns over the effects of waste materials in the environment has been one of the significant social hallmarks of the late 20th century. Essentially every industrialized country has had to incorporate the cost of waste material into the equation of production. Legislative initiatives have led to the passing of very tough laws, by historical standards, which govern the environmental impact of materials processing.Liquid-Liquid extraction is a very common unit operation normally using aqueous and/or organic based solvents. Early work at the Ames Laboratory focused on the use of this technique for the reprocessing of spent fuel from liquid metal breeder reactors by the use of metallic solvents. Recently, we have revisited this area as a means to recycle/reprocess several emerging rare earth based materials, although this method has a much wider range of application. The reinvestigation of this technology is particularly timely as hydrometallurgical based processes are coming under increasing scrutiny in the U.S.A. by the Environmental Protection Agency (EPA). Although technology currently exists to remove contaminants from aqueous based waste streams, often the application of such methods is expensive. With proper design and judicious selection of reagents liquid metal extraction can achieve a high recovery along with a benign waste stream.This process has several possible advantages over other technologies. First is the elimination of aqueous solvents. Therefore, problems associated with disposal or reprocessing of the aqueous carrier are eliminated. Second, with proper system design, very high separation coefficients can be obtained thus limiting the number of stages required. Third, metals are extracted from metals with a metallic product, thereby eliminating the need to re-reduce metal for oxides or other compounds which are the common output for aqueous based extraction procedures."

Jan 1, 1996

By Jack L. Taylor

Single crystals of tungsten grown from powder -metallurgy swaged rod by high-temperative annealing were deformed in tetzsion at temperatures from 2500 to 5000 OF. Orientation of specittzen tensile axis, strained ratrix, and defortnation bands was determined optically by reflections from {110} etch pits. Slip traces meve analyzed and slip directiorz determined. Results indicate that {110}(111) , {112){111}. and {123}{111} type slip occur in tungsten over the terpe,atuve rutge investigated. Slip is orientation-dependent occuvring on tCuzt cowzbitzation oj slip plane and direction which has the highest critical resolved shear stvess. Overshooting appears to be a general occurrence between 2500' and 5000°F. Dejornatiotz bands show rotation in a directiorz opposite to the yotation of tire tensile axis. DEFORMATION in bcc metals has been reviewed by Maddin and Chen,' Keh and eissman,' and most recently by Nabarro, Basinski, and olt. From these reviews it is apparent that some disagreement exists concerning the crystallography of plastic deformation in bcc metals. There is evidence of noncrystallo-graphic slip, the crystal slipping on or near a noncrys-tallographic plane in the (111) zone for which the resolved shear stress is greatest. There is also evidence to indicate that crystallographic slip occurs in the planes of the same zone. On the other hand, there is agreement that the close-packed direction ( 111) is the slip direction in bcc metals. Further, in pure bcc metals4 and alloys the operative crystallographic slip systems are strongly dependent on temperature. Both crystallographic and noncrystallographic slip have been reportede8 in tungsten, a group VIA bcc metal. The number of slip families which operate in the case of crystallographic slip, however, has been in question. The earliest study by oucher' of single-crystal tungsten tested at temperatures of 1800 to 5000°F led to the conclusion that only {112)( 111) type slip operated. Raymond and eumann recently reached the same conclusion studying deformation by rolling of plasma-flame single crystals at 1800°F; however, only [loo] and [110] orientations were studied. Work at high temperatures by Leber and Pughs on tungsten and Chen and Maddin9 on molybdenum suggests that conjugate slip on nonparallel (110) planes may account for the slip on (112) and (123) planes found by others working with bcc metals. The present paper presents evidence of three families or modes of slip in tungsten in the temperature EXPERIMENTAL PROCEDURE Material. Standard microtensile specimens, 0.160 in. diam by 0.640 in. gage length, were ground from commercial powder-metallurgy swaged tungsten rod, type MK. Specimens were heated for 10 min at 5150°F or 6 hr at 5400°F in vacuum of 1 x 105 Torr or less to produce single crystals. At the lower temperature an average of two out of seven specimens heated in a group developed single crystals throughout the specimen length as shown in Fig. 1, the rest remaining wholly poly crystalline. At the higher temperature, three or four out of seven specimens became single crystal. Other than to note that Laue X-ray photographs generally showed sharp, well-defined spots, no attempt was made to assess crystal perfection or measure dislocation density. Two tungsten single crystals grown from the melt by the plasma-arc process were also used for this study.

Jan 1, 1967

By J. Chipman, M. N. Dastur

The importance of dissolved oxygen as a principal reagent in the refining of liquid steel and the necessity for its removal in the finishing of many grades have stimulated numerous studies of its chemical behavior in the steel bath. From the thermodynaniic viewpoint the essential data are those which determine the free energy of oxygen in solution as a function of temperature and composition of the molten metal. A number of experimental studies have been reported in recent years from which the free energy of oxygen in iron-oxygen melts can be obtained with a fair degree of accuracy for temperatures not too far from the melting point. Certain discrepancies remain, however, which imply considerable uncertainty at higher temperatures; also several sources of error were recognized in the earlier studies. It has been the object of the experimental work reported in this paper to reexamine these sources of uncertainty and to redetermine the equilibrium condition in the reaction of hydrogen with oxygen dissolved in liquid iron. The reaction and its equilibrium constant are: H2 (g) + Q = H2O (g); K1 _ PH2O / [1] Ph2 X % O Here the underlined symbol Q designates oxygen dissolved in liquid iron. The activity of this dissolved oxygen is known to be directly proportional to its concentrationl,2 and is taken as equal to its weight percent. The closely related reaction of dissolved oxygen with carbon monoxide has also been investigated:3,4,5 co (g) +O = CO?(g); K _ Pco2___ [2] K2= pco X % O [2] The two reactions are related through the wat,er-gas equilibriuni: H2 (g) + CO2 (g) = CO (g) + H2O (g); K2 = PCO X PH2O [3] PH2 X PCO2 and with the aid of the accurately known equilibrium constant of this reaction, it has been shown5 that the experimental data on reactions [1] and 121 are in fairly good, though not exact, agreement. Experimental Method Great care was taken to avoid the principal sources of error of previous studies, namely, gaseous thermal diffusion and temperature measurement. The apparatus was designed to provide controlled preheating of the inlet gases and to permit the addition of an inert gas (argon) in controlled amounts, two measures found to be essential for elimination of thermal diffusion. A known mixture of water vapor and hydrogen was obtained by saturating purified hydrogen with water vapor at controlled temperature. This mixture, with the addition of purified argon, was passed over the surface of a small melt (approximately 70 g) of electrolytic iron in a closed induction furnace. After sufficient time at constant temperature for attainment of equilibrium the melt was cooled and analyzed for oxygen. GAS SYSTEM A schematic diagram of the apparatus is shown in Fig 1. Commercial hydrogen is led through the safety trap T and the flowmeter F. The catalytic chamber C, held at 450°C, was used to convert any oxygen into water-vapor. A by-pass B with stopcocks was provided so that the hydrogen could be introduced directly from the tank to the furnace when desired. From the catalytic chamber the gas passed through a water bath W, kept at the desired temperature by an auxiliary heating unit, so that the gas was burdened with approximately the proper amount of water vapor before it was introdvced into the saturator S. All connections beyond the catalytic chamber were of all-glass construction. Those connections beyond the water bath were heated to above 80°C to prevent the condensation of water vapor. After the saturator, purified argon was led into the steam-hydrogen line at J, and finally the ternary mixture was introduced into the furnace. THE SATURATOR The saturator unit comprised three glass chambers, as shown in Fig 1, the first two chambers packed with glass beads and partially filed with water and the third empty. Each tower had a glass tube with a stopper attached for the purpose of adjusting the amount of water in it. The unit was immersed in a large oil bath, which was automatically controlled with the help of a thermostat relay to constant temperature, ± 0.05ºC, using thermometers which had been calibrated against a standard platinum resistance thermometer. The performance of the saturator over the range of experimental conditions was checked by weighing the water absorbed from a measured volume of hydrogen; the observed ratio was always within 0.5 pct of theoretical.

Jan 1, 1950

By Martin A. Elliott

Recommendations for safe practices in the operation of Diesel engines underground must take into consideration the hazards that might be created if the composition of the underground atmosphere differs from that of normal air. One aspect of this problem was discussed in the second report6/ of this series, which presented the results of tests in which a Diesel engine was operated with mixtures of normal air and exhaust gas supplied to the intake of the engine. Atmospheres .of this type were studied first because they will be present whenever the exhaust was is discharged into the atmosphere of underground workings in which an engine operates. Diesel engines in underground service may operate in another type of atmosphere, namely, one

Jan 1, 1941

By Martin A. Elliott

Recommendations for safe practices in the operation of Diesel engines underground must take into consideration the hazards that might be created if the composition of the underground atmosphere differs from that of normal air. One aspect of this problem was discussed in the second report6/ of this series, which presented the results of tests in which a Diesel engine was operated with mixtures of normal air and exhaust gas supplied to the intake of the engine. Atmosphere .of this type were studied first because they will be present whenever the exhaust was is discharged into the atmosphere of underground workings in which an engine operates. Diesel engines in underground service may operate in another type of atmosphere, namely, one

Jan 1, 1941

By T. T. Lin, N. H. Madsen, K. Groom, B. A. Chin

"The objective of this research is to investigate the feasibility of using infrared sensors to monitor the welding process. Data were gathered using an infrared camera which was trained on the molten metal pool during the welding operation. Several types of process perturbations which result in weld defects were then intentionally induced and the resulting thermal images monitored. Gas tungsten arc using AC and DC currents and gas metal arc welding processes were investigated using steel, aluminum and stainless steel plate materials. The thermal images obtained in the three materials and different welding processes revealed nearly identical patterns for the same induced process perturbation. Based upon these results, infrared thermography is a method which may be very applicable to automation of the welding process.IntroductionAutomatic welding is commonplace in industry today. However, most, if not all, involves preprogramming for performance of a repetitive task. These systems are incapable of correcting for perturbations which arise during the welding process. Control of the welding process requires the identification and monitoring of perturbations in a wide variety of parameters. The varied nature of these parameters and the large number of variables involved have thwarted previous attempts at closed loop control of the welding process. The sensor(s) employed by a control system need to meet rather strenuous requirements. First and foremost of these is that such a sensor must be able to identify and discriminate between perturbations that might affect the quality of the weld, including such geometrical perturbations as a change of direction in the seam between the parts being welded, gaps in the seam or a misalignment of the parts being welded. The sensor should also be able to locate and identify contaminants and impurities in the weld puddle and ahead of it while monitoring the extent of the heat-affected zone and the cooling rate of the metal. The sensor(s) should, additionally, be able to perform these tasks in a time frame that is consistent with automatic control of the welding process. This paper presents results that could aid in the assembly of such a controlled welding system."

Jan 1, 1986

By K. D. Hester

This paper will review the metallurgical aspects of the completed expansion program at Quirke, and the current rehabilitation and refurbishing program at Panel. During the Quirke program, completed at the end of 1977, the plant capacity was increased from a nominal 4,500 to 7,000 short tons per milling day. The expansion of crushing, grinding, neutral thickening and filtering, leaching, partial neutralization, sand-slime separation, sand washing, C.C.D., clarification, ion exchange, mine water treatment, and tailings neutralization and pumping will be considered. The application of Enviro-Clear thickeners in the mine water treatment circuit and in the C.C.D. will be briefly reviewed. An automatic grinding and classification circuit for limestone will also be covered. The refurbishing program underway at Panel will be discussed. The Quirke and Panel plants will be contrasted and compared. In particular, reference will be made to environmental considerations. The innovative system for producing yellow cake at Panel, LAMIX, will be considered as well as the proposed treatment system for Panel tailings.

Jan 1, 1979

By C. L. Berrier, Wm. B. Daly

Jan 1, 1923

At long last, mining is on the rebound in Minnesota?s Iron Range and the excitement is starting to show. The SME Minnesota Section?s annual meeting was once again held in the heart of Iron Range country, at the Duluth Entertainment and Conference Center on the Duluth waterfront. The conference boasted a record attendance of 475 people and its largest-ever trade show. Appearances by Governor Mark Dayton?s new Iron Range Resources & Rehabilitation Board (IRRRB) appointee, Tony Sertich, as well as a local Fox news crew (see clip on SME website [link: http://fox21online.com/news/duluth-mining-conference-breeds-optimism-tech-innovation]) made clear that a lot of eyes [ ] are on the industry as it dusts itself off from the 2008-2009 recession. While the early years of the 21st century were very good to the Iron Range, the global drop in commodities prices and production left many companies reeling and brought back bad memories of the collapse of the industry in the 1980s. However, two years of solid growth and a rebound to above pre-2008 production levels have let the Minnesota mining industry to relax a little and talk seriously about long-term growth and stability.

Jan 1, 2011

By Wm. B. Daly, C. L. Berrier

Jan 1, 1923

Payloader The Frank G. Hough Co. has made available another four-wheel drive tractor-shovel. It has a 1 cu-yd bucket with 60 hp Diesel or 54 hp gasoline power optional. The use of large pneumatic tires, same size all around, and drive on all four wheels gives this new Payloader traction to work effectively in sand, mud and snow, and travel on pavements with- [ ] out injuring the surface. Rear wheel steer with power booster plus short wheel base makes it easy to operate and highly maneuverable. Four speeds in both directions insure fast travel speeds for transport and fast operating speeds on shuttle loading or similar operations. Bulldozer blade, crane hook, fork lift and snow plow attachments are available, quickly interchangeable with the bucket to further increase its multi-purpose usefulness. Circle No. 1

Jan 1, 1952

By David M. Gullikson

As part of its program of petroleum production research the Federal Bureau of Mines has long been engaged in the study and development of systems of analysis of oilfield waters (8, 12, 20, 21, 22, 27, 30).21 However, many of the early chemical procedures developed by the Bureau and widely adopted by the petroleum industry are time consuming, and some are unreliable for determining certain constituents found in California oilfield waters. Because of the need for more rapid and more accurate methods having greater sensitivity with low concentrations of some constituents, a study has been made by the Bureau's Petroleum Research Laboratory at San Francisco, in developing new techniques and modifying previously published techniques for analyzing oilfield waters by flame spectrophotometric, potentiometric, and colorimetric methods. Test solutions were synthesized for testing the suitability and accuracy of the procedures, and the effect of interfering ions. These solutions contained known quantities of characteristic constituents of oilfield waters including sodium, magnesium, potassium, calcium, lithium, strontium, barium, sulfate, chloride, bromide, iodide, carbonate, bicarbonate and borates in a wide range of concentrations. The compositions of these synthetic brines are listed in table 22. Many California oilfield waters contain salts of petroleum-derived organic acids and several synthetic oilfield waters also were prepared to which large quantities of naphthenates or salts of petroleum acids were added.

Jan 1, 1961

By J. E. 214-000-000-010 Warren, M. R. J. Wyllie, T. Meidav, L. Scharon, R. Uhley, A. J. deWitte

By considering the stoichiometry of the underground combustion process, an equrztion was derived relating the point velocity of the combustion front as a function of the air flux, fuel content, efficiency' of oxygen uitilization, hydrogen:carbon ratio, and ratio of carbon dioxide In carbon monoxide produced. In addition, an equation for cnlcrllating the amount of injected air necessary 10 produce the oil from I Cu. ft of reservoir space was derived. This equation has a direct bearing on evaluating compression costs for the process. Values calculated from these equations are in good agreement with experimentnlly obscrvcd values obtained from laborator) tube runs reported in the literature. The equations are also u\eful for atlcrlyzinf: experinlental data for inconsistencie.r.. I NTRODUCTION The injection of energy in the form of heat into an oil-bearing formation as a means of increasing the recovery of oil has been the subject of much discussion and experimentation as far back as 1920. The ideas have ranged from the injection of steam to the direct use of electricity as a means of getting thermal energy into a formation. However, most laboratory and field studies have been confined to the process whereby a portion of the crude in the reservoir is burned to generate the necessary heat to increase the mobility of the oil by reducing its viscosity. A recent paper by W. L. Martin, et al.', described the results of a number of laboratory experiments in which the combustion process was studied in a sandpack. Studies such as this indicate that with the temperatures involved, the oil is partially coked in this process and it is this coke which provides the fuel for combustion. The combustion of this residual coke can be analyzed theoretically by applying simple stoich-iometric principles to the combustion process. It is the purpose of this paper to compare the results reported in these experiments with those obtained from theoretical considerations. The variables studied by Martin, et al, among others, include combustion front velocity, air flux, oxygen utilization, fuel concentration, ratio of carbon dioxide and carbon monoxide in combustion gases, and the hydrogen:carbon ratio of the residual fuel. All these variables come into consideration when the stoichiometry of the combustion process is studied. The experimental conditions and results are tabulated in Tables 3 and 4 of Ref. 1. For purposes of comparison with calculated results, it was necessary to change the units of a number of the variables. UNDERGROUND COMBUSTION STOICHIOMETRY The combustion or oxidation of the carbonaceous residue or "coke" on the sand can be described in terms of the equation: where n is atomic ratio of hydrogen to carbon, m is ratio of moles of CO2 to CO produced, and CH. is taken as the unit molecular weight, realizing that actually the coke has a large range of high molecular weights. Assuming that all the fuel laid down in the sand is burned, the ratio of moles of oxygen consumed to moles of coke can be written as follows. Moles 0MolesMolescoke In terms of moles O2 per pound of coke, where 12 + n is the molecular weight in pounds per mole. If the 0, consumed is measured in standard cubic feet (60°F and 1 atm) and the coke in pounds per cubic foot of formation, 2, then:

By W. Rostoker, A. S. Yamamoto, K. Anderko

ALTHOUGH the corrosion resistance of magnesium and its alloys is closely related to iron content, there has been no direct measurement of the solid solubility of iron in magnesium. Bulian and Fahrenhors;1 and Mitchel]2 agree that pure iron or a limited terminal solid solution crystallizes from the Mg-rich liquid. For this reason a magnetic-moment method was selected to estimate that portion of the total iron content which is not in solid solution. Since iron in solid solution in magnesium cannot contribute to ferromagnetism, the difference between chemical and magnetic-iron analyses should yield the solid solubility. By experimentation it was found that the melting of pure sublimed magnesium (99.995 wt pet purity) in Armco-iron crucibles at about 800°C is a convenient way to introduce small amounts of iron. Melts retained 5, 10 and 20 min at 800°C analyzed 0.003,, 0.005,, and 0.018 & 0.001 weight pet Fe, respectively, after being stirred, heated to 850°C, and cast into graphite molds. The as-cast alloys were pickled in acid (dilute HC1 + HNO3), annealed at 600°C for 3 days, scalped on a lathe to remove the pitted surface, pickled again, extruded at about 100°C to 3-mm wire, reannealed 41/2 days at 500°C, and water-quenched. The specimens were again scalped, pickled, and used both for chemical and for magnetic analysis. Most of the precautions described were intended to prevent iron pickup by contact with tools or superficial iron enrichment by volatilization of magnesium during heat-treatment. It is believed that the specimens ultimately used for test were homogeneous and characteristic of phase equilibria at 500°C. Magnetic Analyses A susceptibility apparatus of the Curie type was used for magnetic analyses. Field strengths of up to 10,400 oersteds could be generated. By this method, an analytical balance measures the force of attraction which a calibrated magnetic field exerts on a suspended specimen. The force equation is as follows f/m = M dh/dy where f/m = force per unit mass of sample M = magnetic moment per unit mass dH/dy = magnetic field gradient The dH/dy characteristic of the instrument is determined by the use of a standard palladium sample, and the calibration is made independently for all values of H. Since a large finite field is required to saturate an assembly of ferromagnets, it is necessary to measure the apparent magnetic moment for increasing steps of H until a saturation value is obtained. The percentage of iron in the sample as free ferromagnetic iron may then be computed simply C= 100 (M1/M1) where C = percent content of undissolved iron in sample M1 = saturation magnetic moment of sample per unit mass M1 = saturation magnetic moment of iron per unit mass taken as 217 emu-cm per gm There is no serious difficulty in applying this method except for the unusual magnetic behavior of very fine particles of ferromagnetic substances. It has been found and is the basis for a widely accepted theory that with sufficient subdivision, the magnetic fields required to saturate and the coercive force after saturation rise to exceedingly high values. Recent work on precipitates of Fe and Co from copper solid solutions8 showed that about 5000 oersteds were necessary to approach saturation. The magnetic moments as a function of field strength measured in the present investigation are listed in Table I. Only the 0.018 wt pet Fe alloy yielded a magnetization curve with a fairly well-defined saturation plateau at 3.76x10 -2 emu-cm/ gm. This corresponds to 0.017 & 0.001 wt pet Fe in the alloy. This indicates that the solid solubility must be of the order of 0.001 wt pet Fe. The magnetic-moment data of the other two alloys are badly scattered, indicating that the amount of ferromagnetic iron in these samples is so low that the magnetic forces acting on them cannot be measured accurately by the analytical balance used. Nevertheless, the fact that even the 0.003, wt pet Fe alloy shows ferromagnetism indicates that the solid solubility must be below that value. Acknowledgment This work was sponsored by the Pitman-Dunn Laboratory of Frankford Arsenal, Philadelphia, Pa. The support and permission to publish are gratefully acknowledged. References W. Bulian and E. Fahrenhorst: Zeic. Metallkunde, 1942, vol. 34, pp. 116-170. 2 D. W. Mitchell: AIME Transactions, 1948, vol. 175, pp. 570-578. 3 G. Bate, D. Schofield, and W. Sucksmith: Philosophical Magnsine, 1955, vol. 46, pp. 621-631.

Jan 1, 1959

By H. M. Cyr, T. F. Steele, C. W. Siller

The development of a new metallurgical roasting device is described. It consists of a refractory column into which air is injected at various levels, forming several superimposed fluidized beds with no supporting grates. When pelleted zinc sulphide concentrates are charged, the roasted product needs no further sintering before reduction to metal. WHEN a gas such as air is blown upward with increasing velocities through a loose mass of solid particles, marked changes in the physical behavior of the particles are noted. At first, when the velocity of the gas is insufficient to support any of the solid, the mass constitutes a "fixed bed." As the gas velocity increases until the pressure drop through the bed approaches the effective weight of the bed per unit area, the bed expands until the solid particles are supported by the air rather than by the lower particles. Some vibration of the particles becomes apparent, but little mixing occurs. This condition is called a "quiescent fluid bed." A further increase in gas velocity imparts more separation and more motion to the individual particles until a condition of turbulence is reached. This "turbulent fluid bed" resembles a rapidly boiling liquid with the characteristic highly agitated diffuse surface and many small eruptions of the boiling mass. Different degrees of turbulence can be generated and all produce excellent mixing. The final stage occurs when the gas velocity becomes so great as to create a "dispersed suspension." Here no surface of the mass is defined and the gas carries solid particles out of their original positions. These changing conditions of fluidization have been studied carefully and pertinent nomenclature standardized by a committee of the American Institute of Chemical Engineers.' Many mathematical analyses2-3 have been made of the forces acting in a fluid bed. These analyses are invaluable, especially for the design of column sizes and selection of equipment. However, in a metallurgical process involving solids of many sizes with changing densities, varying temperatures, and changing gas compositions within the bed, calculations based on theory become approximate. Optimum operating conditions then are best determined experimentally. Many applications have been made of the principles of fluid-bed action by mechanical, chemical, and metallurgical engineers. Especially when good con- tact between reacting solids and gases is desired, very effective results are obtained from fluid beds. They permit excellent temperature control and uniformity throughout a mass of solids in fluid action. Heat transfer to walls and any coolers is high, and fast reaction rates are attained because the solid surfaces are continuously swept clean. The main disadvantages of fluid-bed operations are the danger of short-circuiting in a single bed, danger of incipient sintering which stops action, the necessity of avoiding large changes in particle size or density during roasting, and dust losses when particles of the charge are carried out with exit gases. In the metallurgical field the roasting of sulphide ores to form oxides and sulphur dioxide appears to combine several operating conditions which can be achieved to advantage in a fluid bed. Roasting involves a solid-gas reaction where a high reaction rate is necessary for high capacity, where good temperature control is important in order to prevent sintering, where good heat transfer is needed, and where the density of the solids, when changing from sulphides to oxides, is not largely changed. Short-circuiting, however, constitutes a major problem when a single fluid bed is used. Because of the turbulence of the bed, an entering particle may be in the region of the discharge before it is roasted. Hence, to attain a satisfactorily low sulphur in the calcine, a long average residence time with correspondingly low capacity is required. The solution to this difficulty is the use of multiple stages, which in the conventional fluid-bed design requires separate hearths with feed and discharge mechanisms for each stage. A further practical difficulty in fluid-bed roasting of flotation zinc concentrates is their fine particle size which makes a true fluid action without excessive carry-over of dust very difficult to attain, especially when the large air volumes necessary for high capacity are used. A New Design After considerable experimentation in the laboratory and on a semipilot-plant scale, a new method and equipment for roasting were devised which provided a unique solution to these problems. A detailed account of this development appears in the patent literature," and many of the variations of this development reported herein are the subject of

Jan 1, 1955