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By H. Groeneveld, C. A. Connally, P. J. Hoenmans, J. J. Justen, W. L. Mason

A miscible displacement pilot using a slug of LPG driven by separator gas was conducted in the Cardiurn reservoir of the Pembina field. The injection pattern was a 10-acre, inverted, isolated five-spot. Upon completion of the LPG-gar phase, an experiment was conducted using a slug of water followed by gas. Calculated performance of the pilot is compared with actual performance. Equations are developed to calculate the distribution of LPG into zones of varying permeability, to estimate the progress of the flood at different times in the various zones and to estimate gas rates after breakthrough. The analysis indicates that permeability stratification was a dominant factor in controlling oil recovery and that oil was completely displaced from the swept pore volume. The results of the pilot indicated that miscible flooding is a practical means of pressure maintenance in this reservoir. The total recovery from the pilot area was good in spite of the early breakthrough of LPG. The effects of stratification were reduced by injecting a slug of water into the partially swept reservoir. INTRODUCTION The Pembina field,' located in Alberta, is the largest oil field in Canada and one of the largest in the North American continent. The reservoir is a stratigraphic trap producing from the Cardium sand. Neither bottom water nor free gas has been found. The recovery of oil by the natural depletion mechanism has been estimated at 12.5 per cent. Pressure maintenance studies of various areas have indicated that the recovery can be increased 21/2 times by water flooding, and a large area of the field is presently under water flood. However, reservoir studies of the North Pembina area indicated that miscible flooding might be competitive with water flooding. A pilot test was conducted to evaluate the performance of a miscible flood. A 10-acre, inverted, isolated, five-spot pattern was selected for the pilot. The pattern area was large enough to minimize wellbore fracturing effects and contained sufficient oil to provide significant working numbers. The performance of each of the four producers could be evaluated individually and compared. In the event of breakthrough in one direction, the effect would be isolated from the other producers. The use of a single injector minimized the volume of LPG required, and, because of the high mobility of gas, one well was sufficient to inject the necessary daily volume to replace the high rate of production. With four producers, the test could be completed in time for results to be evaluated, additional engineering studies to be made and a unit to be formed before the reservoir pressure in the North Pembina area declined below the bubble point. The pilot was located in an area developed on staggered, 80-acre spacing. The injection well was drilled at a regular location, while the four producers were drilled 467-ft north, east, south and west of the injector. Each quadrant and its associated producer were identified according to their direction from the injector— that is, north, east, south or west. The eight surrounding producers on 80-acre spacing were shut in to isolate the pilot area and provide for reservoir pressure observation. The pilot wells were completed using permanent-type completion techniques. After coring, casing was run through the pay section and cemented. Inside 51/2-in. casing, 2 1/2-in. tubing was hung. The wells were perforated opposite the Upper Cardium sand and lightly fractured. Fracturing volumes, rates and pressures were low to minimize the extent of the fractures. The fracturing treatments average 1,000 lb of 20-40 mesh sand in 700 gal of a low fluid-loss sand-carrying agent. Feed rates and wellhead fracturing pressures averaged 5.5 bbl/min at 2,535 psig, respectively. After fracturing, the productivity index was measured in each of the five pilot wells. The average PI of the four producers was 0.41 BOPD/psig drawdown. The measured PI'S were approximately the same as PI'S calculated from core analysis data, indicating that the fracturing treatments were just sufficient to overcome

By M. S. Rashid, C. J. Altstetter

Allotropic transformations in cerium have been studied by dilatometric, resistometric, X-ray diffraction, and metallographic techniques. The dilatometric study indicated that, on cooling below O°C, the high-temperature fcc phase, y, transforms partly to the hexagonal phase, ß, and, on further cooling, to the collapsed fcc phase, a. The amount of $ phase present at room temperature is increased by repeated cycling through the a-y transformation. It has been shown metallograPhically that the y-ß transformation has many characteristics of a martensitic transformation. In contrast to the y-ß transformation the ?-a transformation does not give the manifestation of a shear transformation. Small cellular ? domains of random shape and size collapse to a in a short time with no apparent coordination with neighboring domains. The considerable confusion in the literature over the existence of more than one high-temperature fcc phase is discussed. Two such phases have been reported in the literature and an attempt is made in this study to clarify the situation. Twelve fcc and two hcp structures have been shown to be easily reproduced or eliminated. It is proposed that the two "additional" allotropes reported in the literature and fourteen of the phases detected here are not allotropes of cerium but are due to contamination. CERIUM exists in several allotropic forms, but there is some disagreement over what the forms are. Furthermore, the conditions favoring the presence of a particular allotrope and the nature of the transformations from one form to another are uncertain. The objectives of this research were 1) to ascertain the allotropic forms of cerium, 2) to establish the conditions under which the allotropes exist, 3) to study the effects of annealing and thermal cycling on the allotropic transformations, and 4) to study the transformation mechanisms. Dilatometric, resistometric, metallographic, and X-ray diffraction techniques were employed. The form of cerium commonly found at room temperature is fcc and is designated ?. A complex hexagonal phase, 8, forms when y is cooled to slightly below room temperature. At still lower temperatures the y fcc structure transforms to an fcc form with a much smaller lattice parameter, termed a cerium. A bcc form, 6, which exists just below the melting point (800°C), will not be considered further in this work. There is a substantial body of experimental evidence (reviewed by Gschneidnerl) which favors the acceptance of these four allotropes, though some investigators have tried unsuccessfully to observe the ß hexagonal form.'-' There is disagreement, however, over the phase-transformation temperatures, due, in part, to broad hysteresis and overlapping of the transformations between the a, ß, and ? forms. The transformations are also sensitive to prior thermal and mechanical treatment. The differing purity of cerium used by different investigators is undoubtedly a factor. Cerium is difficult to separate from other elements and is quite reactive, igniting spontaneously when it is filed in air. The highest purity of cerium to date is reported to contain several hundred parts per million by weight of impurities, and early investigations were carried out on cerium containing several percent of impurities. There have been reports of more than one fcc allotrope at room temperature. Gschneidner, Elliott, and McDonald5 obtained diffraction patterns of an fcc phase with a lattice parameter about 1 pct less than that of the ? phase, instead of the y phase, on slowly cooling cerium filings from 23° to -198°C and warming them back to room temperature. However, when the sample was heated to 447°C and cooled to room temperature it consisted of only the ? phase. They have designated this new fcc phase "a-? intermediate", and say it is quite sensitive to impurities. After prolonged high-temperature treatment of a powder specimen, Weiner and Raynor2 obtained a diffraction pattern of an fcc phase of lattice parameter about 1 pct less than the ? phase. This they called the y' phase. It could not be reconverted to the y phase and is claimed to be different from the a-? intermediate phase.5,6 Dialer and Rothe3 reported two fcc phases* after cycling their powder specimens between room temperature and -192°C. Gschneidner, Elliott, and McDonald5 suggested that one of the fcc structures obtained by Dialer and Rothe was equivalent to their "a-? intermediate" phase. Table I presents some pertinent data on the proposed allotropes. For the ?(fcc)-ß(hexagonal) transformation

Jan 1, 1967

By Klaus Schwerdtfeger

Activities of lead in Pt-Pb and Pd-Pb melts in the temperature range of 800° to 1200°C have been detev-mined from electromotive-. force measurements 202th the cells Both systems display strong negative deviations from Raoult's law. The data obtained with cell [1] were combined with available data on the activity of PbO in silica-satuvaterl PbO-SbO2 melts to calculate the standard free cnergy of formation 01- liquid PbO. FREE energies of formation of oxides and activities of components in metal and oxide melts can be determined with galvanic cells consisting of a metal phase, an electrolyte containing the oxide of one of the components of the metal phase, and an oxygen electrode. This technique has been used previously to measure the standard free energy of formation of solid sio2, 1 and activities in Fe-si, CO-si,2 Ni-Si,2 and CaO-P2O5 3 melts. The present paper reports activities in Pt-Pb and Pd-Pb melts as measured with the same experimental technique. EXPERIMENTAL METHOD General Considerations. The following cells were used: Pbl (PbO-SiO2)liquid, SiO2 Pt-Pb 1 (PbO-SiOz)liquid, SiO2solidO2 [2] Pd-Pb (PbO-SiOz)liquid, SiO2solid O2 [3] Liquid alloy and' oxide melt were contained together in a silica glass crucible of essentially the same design as described previously.1'2 The PbO-SiO2 melts are ionic conductors.' During the experiment, the silica glass crystalizes in a layer adjacent to the electrolyte. The electrolyte equilibrates with solid silica and hence attains the composition of the Si02-liquidus curve in the system PbO-SiO2 at any particular temperature. Molybdenum wires were used to establish contact with the liquid metal. The oxygen electrode, which reaches the surface of the PbO-SiO, electrolyte from above, consists of a platinum wire inserted into a ceramic tube and provided with a 2-mm-diam platinum bead at its end. Gas of known oxygen partial pressure (pure oxygen of 1 atm: air, or N2 with 1.04 pct 0,) is blown through the ceramic tube onto the surface of the electrolyte. The cell reaction is Pb (metal) + 1/2O2 (gas) = PbO (electrolyte) [4] No oxidation of platinum or palladium ("displacement reaction") occurs. This is to be expected from the noble character of platinum and palladium, but was also shown experimentally, as described in the next section. The galvanic electromotive force of the cell is given by where AG is the change in free energy for Reaction [4], E(=2) is the number of electrical equivalents necessary to form 1 mole of PbO, and F is the Faraday constant. Formula [5] is valid only if no junction potential exists within the electrolyte. Junction potentials occur only when the compositions of the electrolyte are markedly different at the electrodes. Such differences are negligible in the PbO-SiO, electrolyte, as shown in the next section. Since molybdenum contact leads are used, appropriate corrections were made on the measured electromotive forces to account for the thermoelectric effect of the Mo-Pt couple. The thermoelec-tromotive forces were measured separately with a Mo-Pt couple, and were found to vary linearly from 19 mv at 740°C to 40 mv at 1310°C with molybdenum being positive and platinum negative (cold junction at 25°C). Extrapolation of these values to higher temperatures yields values which are in satisfactory agreement with those obtained previously in the temperature range 1440° to 1630°c.1,2 The change in free energy for Reaction [4] is expressed as where chemical potentials of the species. The value of constant for a given temperature because the slag composition is fixed. Inserting [6] into [5] and using appropriate expressions for upb and uO2 the relation

Jan 1, 1967

By Kenric C. Owen

INTRODUCTION Situated 23 miles east of Pretoria the Premier Mine started diamond production in 1903. Two years later it produced the largest diamond yet discovered, the 3 106 carat Cullinan stone. For the period to 1932 when the mine was closed down due to economic circumstances, open cast mining was practised using inclined rope haulage traction and by this time had produced 48.5 million carats of predominantly industrial quality diamonds from 148 million tons of ore. In 1945 it was decided to re-open the mine using underground mining methods. A system using long hole benching was devised (Hodgson and Sewel 1960). This system was later modified but still forms the basis for approximately fifty percent of production. Following the successful introduction of block caving on associated diamond mines in the Kimberley area (Gallagher and Loftus 1960) this mining method was introduced to the Premier Mine in the late 60's and now accounts for nearly 50% of production. This paper will discuss block caving at Premier Mine in the light of our experience and discussion will be directed to the main geological and structural features of the orebody and host rocks and the related constraints imposed on the mining methods. Reference is made to the long hole benching mining method for comparative purposes. GENERAL DESCRIPTION OF OPERATIONS The ore from the block caving and bench mining areas gravitates via ore passes to a twin haulage, 500m below surface. Electric 13 tonne locomotives, each hauling a train of 10 Granby type cars, deliver the ore to two 42" x 48" (1.06m x 1.22m) jaw crushers. The ore is reduced in size to minus 0.15m before being hoisted to the treatment plant on surface. Hoisting is done with 12.5 tonne bottom discharge skips in a five compartment rectangular shaft using two 3 240 H.P. semi automatic Ward Leonard winders. A small single drum service winder operates in the other compartment. Men and materials travel in a separate shaft in a 5,4m x 2,8m cage operated by a Koepi winder. These two shafts are also the main intake airways to the mine. The two main extraction fans capable of 250 m3/s at 3,2 kPa are situated on surface and are connected to the underground workings by an incline and a network of air passes and return airways. GEOLOGY Although there are numerous occurrences of kimberlite bodies in the district, the Premier Mine kimberlite pipe is the only economic orebody. It is roughly oval in shape with surface dimensions of 900m on the long axis and 450monthe short axis. The surface area is 320 000 m2. The kimberlite has intruded a massive body of felsite and norite which is intersected by a number of faults. The contact between the kimberlite and host rock is clear cut and dips inward at an average angle of 80°. Cutting across the pipe and the country rock is a 75 metre thick gabbro sill, the top of which intersects the pipe below the 347m level and dips at 15' to the north west. The kimberlite has been metamorphosed a distance of some 20m both above and below the sill contacts. Age measurements on biotite from the gabbro date the sill as 1 115 million years, thereby providing a minimum age of the pipe. (Pre Cambrian). All other pipes in South Africa are of Cretaceous age (60 million years). A simplified geological plan and section of the Premier Mine orebody is shown in Figure 1. It is thought that the kimberlite intruded in at least three distinct phases. The kimberlites of these different phases can be distinguished most easily by their characteristic colour. BROWN KIMBERLITE. This is the oldest kimberlite and forms a crescent shape in plan on the south eastern side of the pipe. In depth it increases in relative area. Although the brown kimberlite carries the highest diamond grade in terms of carats per ton all the various kimberlites in the Premier pipe are economic to mine.

Jan 1, 1981

By R. F. Hehemann, D. J. Cometto, G. L. Houze

The w transformation in the Zr-Nb system was studied using X-ray diffraction, dilatometric, re-sistornetric, hardness, and metallographic techniques. w forms in a diffusionless, completely reaersible manner on quenching and in a diffusion-controlled manner- on aging. The temperature at which w begins to form on quenching was determined as a Junction of composition and was found to decrease with increasing solute content. w formed bv aging establishes a metastable equilibrium with an enriched ß phase. The ß/w + ß transus has been determined for this metastable equilibrium and employed to rationalize retrogression and reversion phenomena observed in these alloys. The decomposition mechanism is discussed in terms of a gradual or continuous transformation from ß to the w state. BETA- stabilizing alloying elements lower the MS temperature of the martensitic bcc (ß) to hcp (a') transformation in zirconium and titanium alloys. In certain titanium alloys, a lower symmetry modification of the martensitic structure, termed (a"), also has been reported.1,2 These martensitic transformations are suppressed when the amount of the ß-stabilizing element exceeds a critical level. However, the high-temperature ß phase cannot be quenched to room temperature without change. At alloy contents just above the critical level, |ß trans-forms to the w phase when cooled rapidly.3-6 The amount of w in quenched alloys is reduced by increasing alloy content, and this phase virtually disappears above a critical composition.5 In addition to the transformation during cooling, w also can be formed by aging ß at temperatures below approximately 500°C, and significant alloy enrichment of retained 13 accompanies the isothermal transformation.1-8 The structure of LC is closely related to that of the ß from which it forms.9-15 The bcc (ß) lattice can be generated using a hexagonal cell with three atoms located at (000) and ±(2/3, 1/3, 1/3). This cell has an axial ratio of 0.612 and is oriented with respect to the cubic cell such that (0001)H (111)C and [1120]H [101]C. Consequently, there are four possible orientations of the hexagonal cell, associated with the four (111) planes of the bee lattice. Formally w can be obtained from 0 by allowing the two atoms at the ±(2/3, 1/3, 1/3) positions to approach the coordinates ±(2/3, 1/3, 1/2) and there are four equally probable orientations of w for each 0 grain. In titanium alloys w retains the cubic axial ratio of 0.612" and hence also can be indexed as triply cubic, but this is not the case for aged Zr-Nb alloys where w is clearly hexagonal with an axial ratio of 0.622." The lattice parameters and atomic positions of w depend on thermal history and alloy content. The atomic positions (000), ±(2/3, 1/3, 1/2) provide reasonable agreement between calculated and observed diffracted intensities for w in the fully aged condition.10,14 In the quenched condition, on the other hand, the atoms appear to be displaced from the central plane12,13,15 and assume positions ±(2/3, 1/3, Z = 0.42-0.48) rather than ±(2/3, 1/3, 1/2). This results in a structure with trigonal rather than hexagonal symmetry. The readily detectable parameter and axial-ratio changes of w in Zr-Nb alloys make this system especially attractive for studying the structural changes that occur in the formation and aging of w. Particular attention in this investigation has been directed to the relationship between the structure of w in the quenched and aged conditions, and to certain aspects of the reaction kinetics. MATERIALS AND PROCEDURE Zr-5, 12, 17.5, and 25 pct Nb alloys were prepared by a double arc-melting practice, encased in stainless-steel cans and hot-rolled to 1/8-in.-thick sheet.* Charged weights have been employed for the niobium contents and interstitial analyses are reported in Table I. Dilatometric, X-ray diffraction (filtered CuK, and MoK, radiation), metallographic, and hardness techniques have been employed to follow the transformations during isothermal and quench-aging heat treatments. In quenched specimens, the electrical resistivity also was studied. Betatizing was conducted for 1 hr at 900°C. With the exception of the isothermal dilatometric studies, samples were

Jan 1, 1965

By C. J. Frosch, J. A. May, H. G. White, C. D. Thurmond

Gallium phosphide epitaxial layers were grown from the vapor phase on undoped single-crystal galliurn arsenide substrates in silica tubes by an open-tube wet-hydrogen process. The epitaxial layers were grown over a range of water pressures at three substrate temperatures. Excess donor concentrations were determined by surface barvier capacitance measurelrzents without removing the layers from the substrates. The excess dmlor concentration, ND-NA, is fo~ind to vary approxilnately inversely with the pressure of water added to the hydrogen carrier gas. This is the relationship that would be expected for singly ionized silicon donors on gallium sites in extrinsic galliunz phosphide, with the silicon coming from the SiO generated by the reaction of hydrogen with the silica tube. An increase in the partial pressure of water in the hydrogen stream decreases the SiO pressure. The results indicate that ni, the intrinsic hole and electrmt concentration for gallium phosphide at the three substrate temperatures, is smaller than the concentration estimated from available data for the density of states effective masses and the energy gap. Mass-spectrographic measurements confirm that the dono?, introduced into gallium phosphide is silicon. The equilibrium concentrations of silicon in vapor-flown gallium Phosphide have been estimated from available thernzodynamic information that includes the solubility measurements of silicon in gallium phosphide in equilibrium with a gallium-rich liquid phase. Satisfactory agreement with the measured silicon concentrations is obtained. FROSCH1 has described an open-tube process for growing single-crystal Gap from the vapor phase by a GazO transport mechanism. The method depends upon the reaction of H20 in an H2 carrier gas with a heated source of polycrystalline Gap which provides the necessary vapor species. When the temperature of these vapor species is lowered, super saturation occurs and single-crystal Gap will deposit on a suitable substrate. Unintentionally doped single crystals of Gap grown by the wet H2 process in silica tubes are n type. Evidence is presented to show that the donor introduced is silicon, and that a qua si-equilibrium model accounts for the inverse dependence of the donor concentration on the water partial pressure and predicts the magnitude of the donor concentrations. Ainslie et al. experimentally showed a similar inverse relationship between the carrier density and oxygen pressure for GaAs. Emission-spectrographic analyses showed a decrease in the silicon concentration with increasing oxygen overpressure for GaAs. Cochran and Foster suggested the theoretical possibility of suppressing silicon contamination by using Ga20 generated by the reaction of gallium with water vapor. 1) EXPERIMENTAL The apparatus and procedures are essentially the same as those described by Frosch.' The apparatus consists of a 25-mm-ID SiO2 tube extending through a controlled high-temperature flat zone for the location of the polycrystalline Gap source and a downstream temperature gradient falling at a rate of about 14°C per cm. The latter provides the region of super saturation for the location of the single-crystal substrate. The partial pressure of water in the inflowing hydrogen stream, pA2, O was controlled by mixing me-tered proportions of dry H2 with H2 saturated with H2O vapor at 0°C. The total gas flows were about 200 cu cm per min in all experiments. The Gap sources were prepared by pulverizing boat-grown polycrystalline ingots to pass a 20-mesh sieve. The substrates were cut from an undoped single-crystal boat-grown GaAs ingot purchased from Monsanto. This ingot had a carrier concentration of about 1015 atoms per cu cm, a resistivity of about 5 ohm-cm, and a mobility of about 5000 sq cm per v sec at 25°C. Substrates with dimensions of 1 by 1 by 5 x lo-' cm were employed. The growth faces were chemically polished (111) arsenic faces. Epitaxial layers, at least 7.5 x 10-3 cm thick, were grown,. This required from 1 to 24 hr depending upon the Pii2Q values and the temperatures. In all of the runs, the source temperatures were 50°C higher than the substrate temperatures. Samples were prepared

Jan 1, 1968

By Charles Smeal, Robert J. Schafer, Max Quantinetz

Normally metal powders cannot be ground to sub-micron sizes because of welding and agglomeration phenomena. Through the use of selected grinding aids and grinding fluids, nickel and other metal powders have been ball-milled as fine as 0.1 It was found that certain inorganic salts are more effective grinding aids for metal powders than conventionally used surfactants. METAL and alloy powders are used to produce reagents, pigments, coatings, solders, brazes, and parts for industry by powder metallurgy techniques. They are also combined with refractory compounds to produce cermets and dispersion-hardened products. One of the interests at the Lewis Research Center has been to explore the potentialities of the dispersion strengthening process. Since the work of Ir-mann, many investigators have shown that the strength of dispersion-hardened products may increase with decreasing interparticle spacing.24 One approach to achieving small interparticle spacing is to combine fine refractory compounds and metal powders, preferably below 1 in size. In attempting to obtain fine metal powders, it was found that until very recently the best that could be obtained from commercial suppliers, particularly of ductile metals, was about 1.0 . Interest was therefore developed in providing finer metal powders for dispersion-hardening studies. Information obtained from the literature, from others working in the field, and from prior experimental work performed at NASA, led to a consideration of ball-milling as a technique to produce the desired materials. Some of the variables associated with ball-milling are the size, material, and nature of construction of the grinding container; the nature and amount of the grinding material and material to be ground; and the nature and amount of the grinding liquid and grinding aid, if employed, and the grinding time. In all ball-milling, welding and agglomeration can oc- cur as well as grinding. Because of the tendency of ductile metals to weld together, they are difficult to grind.5 The ultimate particle size obtained on grinding is generally the one at which the rate of grinding becomes equal to the rate of welding. To help delay welding and thus obtain smaller particle sizes, grinding aids are often employed. The principal objective of this investigation was to produce submicron metal powders by ball-milling the powders with selected grinding aids and grinding fluids. A secondary objective has been to attempt to explain the variations observed in grinding behavior by considering possible grinding mechanisms and correlating various parameters with grinding effectiveness. Three groups of ball-milling experiments were run; one in which the grinding aid was varied, a second in which the grinding fluid was varied, and a third in which the material being ground was varied MATERIALS, APPARATUS, AND PROCEDURE In the first group of experiments in which the grinding aid was varied Inco Carbonyl Grade B nickel powder initially 2.5 (all sizes refer to average particle size as measured by Fisher Sub -sieve Sizer) was used as the material being ground and 200-proof ethyl-alcohol as the grinding fluid. Surfactants, representative of typical organic structures, were selected as grinding aids. Inorganic salts used as grinding aids were chosen on the basis of the size and valence of their ions. Water soluble salts were used in order to facilitate their removal from the slurry after grinding. In the second set of experiments, grinding of the 2.5- Ni powder was tried in four different grinding liquids; water, cyclohexane, n -heptane, and methy-lene chloride. In this study seven grinding aids selected from those tried in the first group of experiments were employed. In the third group of experiments 200-proof ethyl alcohol was again used as the grinding fluid to mill Cu, Cr, Fe, Ag, and Ni powders of various initial particle sizes' All mill charges contained 300 ml of grinding liquid and 3000 g of 1/2 in. stainless steel balls. When inorganic salts were used as the grinding aid, 70 g of salt and 210 g of metal powder were employed, and with surfactants 6 g of grinding aid and 300 g of

Jan 1, 1962

By W. A. Tiller

The conventional techniques1 for determining the liquidus and solidus surfaces of an alloy system containing more than two components are extremely tedious to use and do not provide a complete picture of the equilibrium relations between solid and liquid alloys. These techniques are unable to yield "tie-line" information concerning solid and liquid phase equilibrium, a very important parameter in the solidification description of the liquid alloy and a very necessary parameter in the preparation of "zone-levelled" alloy crystals. The tie-line in a polycomponent system is analogous to the partition coefficient, k, in a binary system, it gives the composition of the solid, Cs, in equilibrium with a liquid of composition CL. That is, CS = kCL, where CL = [CO, c1,...Cn] denotes the concentrations of the n + 1 constituents, and k = [ko, kb ,...kon] denotes the gross partition coefficient for the elements between the two phases; thus, k is the tie-line in this system. To provide complete information concerning the two-phase equilibrium in a polycomponent system it is necessary to know both the liquidus surface and the gross partition coefficient. From these two the solidus surface is obtainable. The conventional techniques are unable to provide this information in other than a binary system so we must look elsewhere. In recent years considerable insight has been gained into the correct description of the liquid-solid transformation, 2,3 and controlled solidification experiments may now be designed to both facilitate and enhance equilibrium diagram studies. In the present paper consideration is given to two methods for obtaining the liquidus surface and the tie-lines in polycomponent systems. The methods to be described below deal with the solidification of an n + 1 constituent liquid alloy of initial composition [co, Co ,...Con], where the superscripts refer to the elements present and the Oth element is considered as the solvent in which the n solutes are dissolved. The general assumptions made in the treatment are the following: (i) the solid and the liquid at their interface are in equilibrium during the growth of the solid phase, (ii) there is no diffusion in the solid phase, and (iii) the liquid phase is completely mixed and is therefore homogeneous in concentration. METHOD I In this section a general experimental method will be described which, in principle, is capable of giving an exact description of the liquidus surface and tie-lines. Consider the unidirectional solidification of the liquid alloy specimens L cm in length (freezing either horizontally or vertically). Allow the sample to be frozen very slowly from one end, as indicated in Fig. 1, with complete mixing in the liquid, and then analyze the solid bar to determine its chemical constitution as a function of position, x, along the bar. Let Fig. 2 represent a possible distribution of the ith constituent along the bar. At the point x' the concentration of the ith constituent is C1/5(x'), and the average concentration of the rest of the bar between x' and L is given by C:(X' - L) where [ A(x) c1s(x)dx c1/s(x'-L) = f A(x) dx x * and A(X) is the cross-sectional area at x. In a similar manner. all the Cf(x' - L) may be determined. Thus, the gross artition coefficient k for liquid of composition [Cs(x - L),...Cs(X' - L)] is given by -ko= CUs')/Cos(x' - L)" k0 = csn{x')/cs(x'- L) During the freezing of a charge of length L, the liquid composition may vary over a wide segment of the phase diagram and the gross partition coefficient over this segment of the phase diagram may be determined from one, bar. Fig. 3 illustrates the magnitude of Cs(g)/C,' as a function of the fraction g of the bar which has Solidified.2 We can see that the concentration in the bar will vary over a range of about 15 wt pct for C,' = 10 wt pct and k0 = 0.5. It appears that 4 or 5 specimens would be adequate to study a simple binary eutectic phase diagram.

Jan 1, 1960

By W. A. Backofen, D. H. Avery, G. A. Miller

An evaluation has been made of the relative importance of yield strength (?) and stacking-fault energy (y) to the rate of fatigue-crack growth in materials of fcc structure. Pure copper and its solid-solution al-loys with aluminum and nickel were chosen for the study because they provided sufficient range in both quantities of interest that either could be varied independently of the other. Experiments involved alternating tension and compression of flat specimens which were prepared with sharpened internal notches so that most, if not all, of the crack-nucleation interval could be eliminated. Growth rate (dC/dN) was concluded to be proportional to the square of the plastic-strain amplitude (€,,) over a strain range of approximately 6x 10-4 to 6 x 10-3. The factor, k, linking dC/dN and ep in dC/dN = kEp2 increased and decreased with corresponding variations in y, but it did not respond syste?>/atically to change in ay, indicating that y is the significant variable in crack growth at constant plastic-strain amplitude. In polycrystalline material, k varied by a factor of 5 over the available range of y. In a few single-crystal experiments on Cu-A1 alloys the growth rate responded less strongly to change in y. It has been suggested that single crystals behave somewhat differently than poly crystalline material because there is more extetnsive substructure near the grain boundaries in the latter, and this facilitates crack advance by separation along subgrain boundaries. A point of some controversy in current work on fatigue relates to the effects of strength and stacking-fault energy on crack growth. In recent experiments a separation was made between the cycling intervals for crack nucleation and the subsequent growth that eventually ends a specimen's fatigue life.' The study was carried out on Cu-A1 alloys primarily, fatigued in alternating four-point bending to constant deflection. A nucleation interval of about 10' cycles (at a total strain amplitude = 0.2 pct) was found to be insensitive to aluminum content in the range 0 to 7.5 wt pct, while the growth period was increased approximately forty fold over the same compositional range. The increase was not in any sense linear, however. Rather, most of the change occurred below 4 pct A1 or a stacking-fault energy, ?, of about 15 ergs per sq cm. It was argued that the plastic-strain amplitude was approximately constant, and therefore the effect of composition must have grown out of the reduction in stacking-fault energy. Several studies have shown that, with high ?, cross slip is encouraged, subgrain structure is introduced during fatigue, and cracking is aided through propagation along subgrain boundaries.1-5 Therefore, lowering ? sufficiently to interfere with substructure formation would be expected to retard growth rate. On the other hand, it is a general rule that resistance to fatigue cracking increases as strength is raised. Accordingly, there might still have been some doubt that Y was the controlling variable, since strength would be increased as y was lowered by the aluminum additions. To help in dispelling that doubt, an experiment was made on a polycrystalline Cu-Ni alloy similar in strength to the Cu-A1 alloys but of higher ?; the crack-growth interval was found to be essentially that of pure copper.' Further support for this position on stacking-fault energy as it relates to crack growth is derived from work by Boettner and McEvily,6 in which the actual crack-growth rate was measured on samples previously notched so as to minimize the nucleation period. Unfortunately, it was necessary in isolating strength level to compare different alloy systems and grain sizes. Recognizing the complication, it was still concluded that growth may be retarded by a reduction in y, per se. A related study has also been made by Roberson and Grosskreutz.7 The zinc content of a brass was systematically changed to alter strength and stack-ing-fault energy, although not below the 15 ergs per sq cm at which pronounced change in growth interval was found in the earlier work. The results were limited to more or less conventional S-N diagrams so that nucleation and growth events could not be separated. No definite conclusions were drawn, but

Jan 1, 1967

By C. B. Daellenbach, T. D. Tiemann

The prevention of quartz flotation by chelation of activating ions with the tetrasodium salt of EDTA in oleic acid flotation was investigated using a small vacuum flotation cell. It was found that flotation of quartz could be entirely suppressed in the presence of activating ions during complete flotation of hematite. It was further shown that the concentration of activating ions liberated from Wisconsin Gogebic taconite is sufficient to float quartz in an oleic acid system. Large tonnages of low grade siliceous iron ores occur on the iron ranges of the Lake Superior district. Although the lower grade nonmagnetic types are currently not of economic importance, they constitute a large future potential source of iron and steel, and hence have been the subject for extensive research on their beneficiation. TACONITES Of particular interest to the Dept. of Minerals and Metals Engineering at the University of Wisconsin have been the low grade nonmagnetic taconites of the Wisconsin Gogebic Range. These occur as five members of the iron formation and have been described in detail elsewhere.' Essentially they consist of an intimate mixture of hematite, goethite and quartz, with minor amounts of siderite, magnetite, iron containing silicates, and manganese minerals. A typical mean analysis based on the Bureau of Mines analyses' is: SiO2-52.50%, Fe2O3-43.40%, (Fe-30.38%), A12O3-1.15%, P2O5-0.07%, Mn2O3-0.29%, CaO-0.07%, (S-0.03%), Loss on ignition-2.00%. The quartz in these ores is of a microcrystalline variety,2 and so intimately associated with the iron oxide minerals that extremely fine grinding, in the order of minus 325 mesh, is required for liberation. During grinding and subsequent flotation, the concentration of quartz activating ions in the pulp becomes sufficiently high to activate quartz which floats along with the iron minerals in the presence of oleic acid. cook3 and co-workers concluded that oxidized iron ores released appreciable quantities of quartz-activating ions in water pulps. This is shown to be true in the present investigation. As a matter of fact, application of this phenomenon, as well as the intentional addition of activating calcium ions, is made use of in the an ionic flotation of silica from the iron oxide minerals.4,5 In view of the above, it becomes almost impossible to effect a sharp separation of quartz in the oleic acid flotation of the iron oxide minerals from these taconites, even with satisfactory liberation. This fact led to the current investigation to find a means of linking the activating ions with a chelating agent. The aim was to establish basic data for the quartz-water-oleic acid system which might not only be applicable to iron ores, but also to the flotation of other siliceous ores as well. EXPERIMENTAL METHODS Vacuum Flotation Cell: The vacuum flotation used in this investigation is similar to that used by previous investigators.6,7,8 The cell consisted of a 100 ml graduated cylinder with the lip removed. Vacuum from a water aspirator was applied to the cell through a trap; suitable tubing, and a rubber stopper inserted in the top of the cell. Constant absolute pressure was maintained by means of a manometer connected to the trap with a tee. Flotation: The required amount of activating ion solution was pipetted into a beaker. This was then diluted to 99.0 ml with water having a pH below that desired for the test, or so adjusted with HC1. After addition of 1.0 ml of oleic acid solution (2.0 mg oleic acid per ml), the pH was readjusted to the desired value with NaOH, and the entire solution transferred to the cell containing 1.5 gm of quartz. After vigorously agitating the cell and its contents for 2 min, the vacuum was applied to the cell and the estimated degree of flotation observed for a 3-min period. Activating ions studied included Ca++, Mg++, Al+++, and Fe+ + + added as chloride solutions. In addition,

Jan 1, 1964

By H. Dykstra

Calculated wellbore pressures were obtained for parameters of radilcs ratio and permeability. In all cases bur two, after-production was allowed to occur for one day. The calculated pressure build-up data were compared with actual pressure build-up data from a condensate well. The paper discusses the comparison, gives reasons for, inability to match calculated (2nd actual data, and presents conc1usions derived from the comparison. INTRODUCTION Considerable information has been published on the decline in wellbore pressure for oil and gas fields resulting from production of fluids. Considerable information also has been published on pressure build-up for oil fields, but relatively little has been published for gas and condensate fields. Perrine' summarized the equations derived for pressure build-up in oil wells and showed how the different methods could be applied. On the other hand, very little theoretical information has been published on pressure build-up in gas or gas-condensate wells.2-4 Tracy,' by pointing out the similarity between the equation describing oil wellbore pressure decline and the equation describing gas wellbore pressure decline, showed how methods of pressure build-up analysis could be applied to a gas well. In analyzing pressure build-up data for gas or gas-condensate wells, it would be very desirable to compare actual pressure build-up data with calculated pressure build-up data. Such a comparison would lead to a better feeling for the quantitative picture of gas-well build-up curves and would help to establish a degree of confidence in a given build-up curve. This paper discusses the comparison and presents conclusions made from it. Calculated wellbore pressures are given for parameters of radius ratio and permeability. In all cases but two, after-production was allowed to occur for one day. The work was done in an attempt to evaluate the reserves of a gas-condensate field. As will be discussed later, it was not possible to make an evaluation. METHOD OF CALCULATION The method used for solving the depletion and pressure build-up behavior for a gas-condensate well was that developed by West, Garvin and Sheldon.5 or the IBM 704 computer program used, it was assumed that liquid condensing out of solution would have only a minor effect on the flow behavior. Therefore, the field was treated as having single-phase flow, with the gas saturation S, remaining constant at unity minus the connate-water saturation Sw. As will be discussed later, this may not have been a good assumption. It also was assumed that oil production could be considered as equivalent gas production by using a conversion factor based on an analysis of the liquid produced. An outer boundary condition of no-flow was assumed. BASIC DATA The data required for the study were reservoir properties, fluid properties and production data. Reservoir properties included the following: thickness h, 179 ft; porosity, 0.194; connate-water saturation, 0.43; gas saturation, 0.57; permeabilities k, 1.0, 0.5, 0.25 and 0.15 md; radius ratios re/rw, 800, 1,000 and 2,000; wellbore radius rw, 5 in.; initial reservoir pressure P, 6,529 psia; and reservoir temperature, 272°F. The selection of permeabilities was based on core-analysis data showing an average air permeability of about 2 md. With a relatively high connate-water saturation, the average effective gas permeability would be about one-half, or less, of the air permeability. The selection of radius ratios was based partly on the observed rapid decline in wellbore pressure during production and partly on the fact that the well was believed to be located in a relatively small fault block. Reservoir fluid properties were obtained from a reservoir fluid study on a recombined sample of gas and condensate. Gas formation-volume factors were calculated from pressure-volume measurements made at reservoir temperature. Gas viscosities were calculated by the method of Carr, et al,G from an analysis of the re-combined sample. These data are shown as a function of pressure in Table 1. The production schedule from the gas-condensate

By R. G. Treuting

Germanium single crystals strained in tension at 600°C slip on the {Ill} plane and, macroscopically at least, in the <110> direction. Deformation is in homogeneous: various localized rotations are observed, as is a banding consistent with secondary slip banding. The structure after deformation is polygonized with a domain size of about 2x1O-3 cm. In relaxation tests, an incubation period prior to flow is observed, of duration inversely related to temperature and applied stress. Under continuous loading, there is a sharp first yield point. A critical resolved shear stress therefore must be cited with respect both to temperature and to rate of loading. At 600°C, when loading proceeds at 2900 psi per min, it is 1310 psi. The yield point phenomenon is suggestive of Cottrell&apos;s solute atom atmosphere theory and five points of qualitative agreement with this theory are found. PLASTICITY of germanium at elevated temperatures has been reported by Gallagher,&apos; who ascribed it to slip on {Ill) planes and described some associated effects. Preliminary experiments with single crystals of silicon and germanium loaded as simple beams confirmed {ill) as the slip plane of both materials.V his was demonstrated by the standard technique employing traces on two surfaces of known angle on a deformed crystal of known orientation.3 These experiments did not fix the slip direction, since more than one glide system operated. Uniaxial tensile straining is preferred for this purpose in order to restrict slip to one predominant system and to provide an unequivocal determination of the orientation change with respect to the stress axis. Experimental Method Specimens were diamond-sawed from germanium crystals containing about 5x10-5 wt pct Sb prepared by the zone-leveling process described by Pfann and Olsen;4 these specimens measured about 81/2 in. long, 0.20 in. wide, and were of various thicknesses from 0.035 to 0.060 in. Prior to testing, a specimen was coated over 1 in. or more of length at each end with Apiezon wax, chemically polished (in a solution of 15 ml HF, 25 ml HNO,, 15 ml CH3COOH, and 3 to 4 drops Br2), and dewaxed in warm xylene. A brief re-etching after scribing through a complete wax coating with vernier dividers provided gage marks at 0.200 in. intervals on the polished surface. A specimen with grips soft soldered to the ends was passed through the furnace tube and the grips pinned to the tensile machine in series with a stress gage. The Schopper testing machine is best described by reference to the illustration on p. 107 of Schmid and Boas5 and is operated with the pendulum arm locked, fixing the upper head. Load is applied through the screw-driven lower head, manually or by reduced speed motor. The furnace is 21/2 in. long surrounding a 4x7/16 in. ID quartz tube and was positioned about the specimen to permit free motion. The inert or reducing atmosphere required was sufficiently provided by a flow of helium introduced at the center of the furnace tube, with the tube ends loosely plugged with asbestos paper. Surface corrosion was slight. The stress gage employs a Be-Cu strip with SR-4 units incorporated in a simple bridge network with provision for balancing and calibrating. The bridge output on loading is fed through a Leeds and North-rup dc amplifier to a Speedomax 10 mv recorder, and calibration is obtained by dead loading. Experiments of two types have been conducted. Most have been in relaxation at constant elongation. One stress-strain curve has been taken with the machine continuously driven. Following extension of a specimen, Laue X-ray photographs were taken to obtain the orientation change between deformed and undeformed regions, recorded on a single film by translating the specimen in a plane normal to the beam between exposures. Sequences of such multiple exposures were made on some specimens to include the entire orientation range on one film. Slip Direction To obtain a maximum orientation change with a single slip system, crystals of very closely <110> axial orientation were used. The classic determination of slip direction rests on establishing that direc-

Jan 1, 1956

By W. B. Morrison

The principal factors influencing the total percent elongation of a lead-tin eutectic and several low-alloy steels which exhibit superplasticity were investigated. These factors are: a) Strain-rate sensitivity of the stress (m). b) Specimen geometry; in particular, diameter-to-length ratio (d0/l0), and surface irregularity (e.g. notches). A feature of the tensile deformation of a superplastic alloy is the early appearance of a neck which continues to extend throughout the test. As a result the total elongation is directly related to the diameter-to-gage-length ratio. The strain-rate sensitivity of the stress varies during extension, mainly because of microstruc-tural changes. A satisfactory correlation exists between the minimum strain-rate sensitivity and total elongation, as indicated in the equation shown below. Notches cause a considerable reduction in total elongation and their effect is greatest at high values of strain-rate sensitivity. An initial notch depth exists below which there is no appreciable effect on elongation. An equation relating elongation to strain-rate sensitivity and specimen geometry is proposed, THE total percent elongation of a tensile specimen is usually regarded as a measure of superplasticity. However, little attention has been given to the fact that total elongation is also a function of specimen diameter and gage length, even though the importance of geometry has long been recognized in the tensile testing of materials in which elongations are relatively small.* In the present study, the effect on superplas- tic extension of the ratio of specimen diameter to length was investigated and an analysis was made of strain distribution along the gage length. Superplastic alloys are characterized by having a flow stress sensitive to strain rate but relatively insensitive to strain.2"&apos; In an earlier study,5 it was found that the strain-rate sensitivity of several low-alloy steels changed during the test and that the minimum value correlated best with total elongation. In the present study, the variation of strain-rate sensitivity during the straining of a lead-tin alloy was investigated. EXPERIMENTAL PROCEDURE Lead-tin eutectic alloy (32 pct Pb 68 pct Sn), made from high-purity lead and tin, was cast in the form of 1-in. diam rod. The rod was cold-rolled in stages to 0.25 in. diam and then swaged to 0.125 in. diam. Samples were cut from the rod at various stages of the mechanical working process. Tensile test specimens were then made by attaching threaded steel ends to the rods by an epoxy-base thermosetting adhesive which required a setting treatment of 2 days at room temperature. The rods were seated in the steel ends in holes approximately 0.01 in. oversize. The test pieces thus made were of various diameters and gage lengths. These were stored at a temperature of about -70°C (-94°F) until required for testing. The distribution of strain along the gage length of a specimen was determined at various stages of the tensile test. The lead-tin alloy was superplastic at room temperature and direct observations during testing were simple. The gage length was divided by reference marks into five initially equal units. These reference marks were made with ink and were reinforced during the test when the initial marks became faint. Photographs were taken, at intervals, of the deforming specimen and measurements of the elongation in each of the gage units were made on these photographs. Tests were also done on several superplastic low-alloy steels whose properties were described earlier.5 The chemical compositions of these steels are given in Table I. A diagram of the notched tensile specimen used in the steel tests is shown in Fig. 1. The specimens were tested at 900°C (1650°F) in a furnace through which a mixture of He + 2 pct H was continuously circulated.5 RESULTS Strain Distribution. Approximately 20 tests on lead-tin alloy specimens were conducted to determine the strain distribution during the test. An example is shown in Fig. 2 of the strain distribution in the gage

Jan 1, 1969

By Gerald G. Griswold, James O. Greenslade, Cherie Tilley, Richard Reseigh

INTRODUCTION The Harrison Western Corporation, a leading Denver based mine contracting and engineering concern, is presently engaged in sinking two 1,006 m (3,300 ft) shafts for the Phillips Uranium Corporation at their Nose Rock Project, approximately 13 miles northeast of the small community of Crownpoint in McKinley County, New Mexico. The Nose Rock Project is the first attempt by the Phillips Uranium Corporation to tap the deep uranium reserves in what has become known as the Grants Mineral Belt. (See Figure 1) Project Description Phillips Uranium Corporation&apos;s plan for the large 2700 metric ton per day (2950 tons/day) mining facility calls for a series of deep access and ventilation shafts ranging from 4.27 m (14 ft) to 5.49 m (18 ft) in diameter to approximate depths of 1,006 m (3,300 ft). The initial pair of shafts consists of one production shaft and one ventilation shaft separated by a distance of 91 m (300 ft). The interbedded layers of sedimentary sandstones and shales to be penetrated by the shafts contain several major water producing aquifers, the deepest being the mineralized zone called the Westwater Canyon Member of the Morrison Formation. A series of temporary and permanent water pumping stations is planned. Generally, the temporary stations are located above major aquifers to facilitate water removal while sinking through the aquifer and the permanent stations constitute what, in the final mode, will be the mine dewatering system. In addition, Phillips Uranium Corporation has In- stalled and is maintaining a system of depressurization wells that temporarily pump the major aquifers and considerably reduce the water inflows during shaft construction. The major aquifers are also chemically grouted prior to sinking. Site work for the project was initiated in the fall of 1976. Full scale shaft sinking commenced in November of 1977 on the 4.88 m (16 ft) diameter ventilation shaft and on the 5.49 m (18 ft) production shaft by another contractor. Harrison Western Corporation began work on the project on November 4, 1979 wlth the production shaft at a depth of 633 m (2,076 ft) and the ventilation shaft at a depth of 474 m (1,554 ft). This paper will address only the portion of shaft sinking completed by Harrison Western. Geology and Hydrology The Nose Rock Project is located on the Chaco Slope in the southern extreme of the San Juan Basin in northwest New Mexico. The southern San Juan Basin is generally bound by the Defiance Uplift to the west, the Zuni Uplift to the south and the Nacimiento Uplift to the east. The Grants Mineral Belt occupies most of the southern portion of the San Juan Basin and this project is located on the northern extreme of the Grants Mineral Belt. The San Juan Basin is comprised of sedimentary rock of continental, marginal-marine and marine origin, that dip northward from the Zuni Uplift and Chaco Slope into the interior of the San Juan Basin. (See Figure 2) Major Formations The major geologic formations to be penetrated range from mudstone and shales to siltstones and sandstones. The sandstones are highly productive aquifers which, under static conditions, would flow artesian. Water temperatures in the aquifers are high and therefore are a force to be dealt with. Temperatures range from 18ºC (65OF) in the upper aquifers to 48ºC (118º&apos;F) in the lower. The mudstones are generally bentonitlc. (See Figure 2) GALLUP SANDSTONE: The Gallup Sandstone is the first major regressive wedge in the San Juan Basin of the Cretaceous era and at this project is about 35 m (115 ft) thick. It is medium grained and prior to depressurization carried a hydrostatic water pressure of over 72.5 kg per cm2 (1,031 psi) which 1s artesian. Compressive strength ranges from 334.7 kg per cm2 (4,760 psi) to 421.8 kg per cm2 (6,000 psi). Water temperature is approximately 30°C (86°F).

Jan 1, 1982

By D. P. Kedzie, R. A. Dodd

The fatigue strength, fatigue hardening, and effect of fatigue deformation on subsequent age hardening of supersaturated Al(Cu) solid solutions have been determined as functions of alloy composition and temperature. The fatigue strength/tensile strength ratios, determined at 150°, 25°, and -195°C, decreased with increase in alloy content for all temperatures, but the F.S./U.T.S. ratios at -195°C decreased much more rapidly than did the ratios for 150" and 25°C. This suggested that strain aging and/or age hardening occurred during tests at higher temperatures. Additionally, the F.S./U.T.S. ratios at 150°C exceeded those at 25°C for all compositions, indicating greater strengthening during fatigue at 150°C. The effect of fatigue or tensile deformation at 150°, 25°, and -195°C on subsequent age hardening showed that the deformatzon increased the rate of precipitation and indicated that mechanically produced vacancies were probably formed during deformation. Fatigue hardening was studied at 150°, 25°, and -195°C, and the effect of room-temperature rests after 10 and 100 cycles was examined. The results confirmed that strain aging occurred at the higher temperatures . DURING the last 15 years various mechanisms of fatigue crack nucleation and growth based on dislocation and vacancy interactions, operating singly or collectively, have been proposed. The probable consensus of present opinion is that the fatigue process in pure metals essentially involves dislocation interactions, and that vacancies formed by such interactions play a minor or inconsequential role. However, there is some evidence that age-hardened alloys tend to overage during fatigue, probably by local vacancy-enhanced diffusion, and strain aging also might be important in selected cases. Furthermore, it has been established that the behavior of quenched-in vacancies in Al(Cu) and other solid solutions is composition-sensitive. Therefore, it seemed worthwhile to investigate various aspects of the fatigue behavior of supersaturated Al(Cu) alloys and to examine the results in terms of vacancy-enhanced effects. EXPERIMENTAL The alloys used in this investigation were prepared from 99.994 wt pet A1 and OFHC copper, the latter containing 0.04 pet 0 as the principal impurity. Six alloys were made, containing, by actual analysis, 0.58, 0.96, 1.96, 2.85, 4.45, and 5.51 wt pet Cu. They were induction-melted in air in graphite crucibles, cast as 7-in. by 7/8-in.-diam rods in graphite molds, and hot-rolled to 5/8 in. diam. The experimental work was a three-part program involving the determination of a) 10&apos; cycle fatigue stresses as a function of alloy composition and temperature; b) the effect of fatigue deformation on subsequent aging of the supersaturated alloys; and c) fatigue hardening as a function of alloy composition and temperature. For determining the 105 cycle fatigue stresses, a portion of the 5/8-in. stock was machined into Krouse rotating cantilever beam fatigue specimens, 2 in. in length by 1/4 in. minimum diameter. These were tested at +150°, 25°, and -195°C (liquid nitrogen) on a Krouse high-speed machine, with special weights to provide lower -than-normal loading ranges, this being necessitated by the small load requirements of those alloys of lower copper content. For the high-temperature tests a small resistance heater was designed to clear the collets and fit in between the chucks, while for the low-temperature tests a hollow nylon cylinder was used, having closed ends drilled to pass a fatigue specimen, and positioned similarly to the heater. A plexiglass container completely enclosed the fatigue machine; rubber gloves fixed to ports in the walls enabled the machine to be operated from outside the box. A tray of magnesium perchlorate dried the air in the container and prevented both atmospheric corrosion fatigue at room and elevated temperatures and troublesome ice build-up at low temperatures. A total of ten to fifteen specimens was used for each combination of alloy composition and temperature. The result of each test was plotted on a standard S-N diagram, and the next stress was selected on the basis of the trends indicated by previous specimens. In this manner a small portion of the S-N diagram was constructed, and the 105 cycle fatigue stress obtained. Small Krouse fatigue specimens were also used to study the effect of cyclic prestrain on subsequent

Jan 1, 1964

By E. M. Kalar, I. Iwasaki, J. D. Zetterstrom

Several methods of removing fatty acid coatings from iron ore flotation concentrates were tested both on a Mesabi oxidized iron ore and on a magnetic taconite concentrate, and their effects on the duplex flotation process and on pelletizing were compared. Either acid or alkali alone could not remove the coatings, but a combination of such reagents as lime and quebracho, calcium chloride and pyrophosphate, or sulfuric acid and an organic acid (oxalic, malonic, or citric acid) was quite effective. The use of activated carbon was found to be particularly promising. The removal of fatty acid coatings from iron ores is of much practical interest when a pelletizing process is being considered for a concentrate floated with a fatty acid collector or when a duplex flotation process is being considered for upgrading an oxidized iron ore. A duplex flotation process is a fatty acid flotation of iron minerals followed by an amine flotation of the siliceous gangue from the rougher iron concentrate. Such a process is being used in the Florida phosphate fields.&apos; Although in northern Michigan mills fatty acid flotation concentrates have been pelletized successfully, at other locations fatty acid coatings on iron flotation concentrates have proved so undesirable in the agglomeration operation that other methods of concentration had to be sought.&apos; Since fatty acid coatings cannot be removed as readily with a simple acid or alkali treatment from iron oxide surfaces as from Florida phosphates, a combination of reagents, such as lime and quebracho,3 lime and alkali phosphate,4 or sulfuric acid and oxalic acid,&apos; has been proposed. It was also thought that activated carbon might be effective in removing fatty acid coatings due to its high adsorptive capacity. Activated carbon, with its enormous surface per unit of volume, is well known for its exceptional efficiency in removing organic pollutants from industrial effluents. This article presents the practical aspects of the above methods when they are applied to the duplex flotation process and to the pelletizing of iron flotation concentrates. The article also includes a preliminary investigation of the common parameters involved in the depressant activity of the reagents. EXPERIMENTAL WORK Initially, the experimental work was directed towards the optimization of each method for the removal of hydrophobic coatings from iron oxide surfaces floated with fatty acids. Subsequently, the methods thus optimized were tested in the duplex flotation process with an oxidized iron ore and in the pelletizing process with a magnetic taconite concentrate. Preliminary Flotation Tests: Although the three types of chemical treatment reported in the literature were briefly investigated for the purpose of comparison, major emphasis was placed during the preliminary flotation tests on the use of activated carbon because it was thought to have certain advantages over the chemical methods. LIME AND QUEBRACHO - To obtain a flotation concentrate for optimizing the lime and quebracho method of fatty acid removal, the magnetic taconite concentrate was used. The concentrate had a size consist of 90% passing 325 mesh and analyzed 64.5% iron. After a few preliminary tests the fatty acid flotation procedure with the magnetic taconite concentrate was standardized as follows. A 1200-g sample of the magnetic concentrate was pulped in a Fagergren laboratoy flotation cell to 40% solids, conditioned with 0.5 lb of soda ash per ton for 2 min, and then further conditioned with 1.0 lb of Acintol FA-2 per ton for 2 min. After 5 min of flotation, recovery was nearly complete, averaging 98.6% of the weight and 98.7% of the iron. The cell product, which amounted to 1.4% by weight and analyzed 63.2% iron, consisted mainly of relatively coarse middling particles. Since the repro-ducibility of the flotation concentrates produced by this procedure was vey high, the same procedure was used to prepare fatty acid concentrates for each of the six tests of the lime and quebracho method. To test the removal of the fatty acid from the magnetite surfaces by the lime and quebracho method, a fatty acid froth product was returned to the flotation cell, repulped by 30 sec of agitation, and then con-

Jan 1, 1968

By W. O. Philbrook, R. S. Kaplan

Rates of oxidation were studied for levitation-melted samples of Fe-C, Fe-Si, Fe-C-Si, Fe-C-P, Fe-C-Mn, and Fe-C-S alloys oxidized by mixtures of either 5 or 10 pct O2, in helium at several temperatures in the range 1850o to 2050°C. The concentrations of the oxidized elements decreased linearly with time. Mass transport in the gas phase was found to be the rate-controlling step. Ilowever, a mulliple -film model was necessary to account for the flux of iron and manganese vapor counter to the oxygen flow. THE advent of the basic oxygen and spray-refining processes of steelmaking has generated considerable interest in the kinetics of reactions between oxygen-bearing gases and liquid iron alloys. The object of this research was the determination of the role of mass transport in the gas and metal phases and of surface chemical reactions in the overall oxidation process. Of the reactions for elimination of elements dissolved in liquid iron, the oxidation of carbon has been investigated most extensively. Studies by Fuji and Ura,1 Fuji,&apos; and Gunji et a1.,3 done with pilot-scale basic oxygen furnaces, indicated that mass transport of gaseous oxygen was rate controlling when the metal carbon content was greater than 0.15 to 0.30 pct. When the carbon content was less than this critical amount, diffusion of carbon dissolved in the iron was thought to be rate limiting. L. A. Baker et a1.4,5 levitated samples of iron-carbon alloys and oxidized them in CO-CO2, CO-C02-He, and O2-He atmospheres at 1660°C. These investigators found that the metal carbon concentration decreased linearly with time and their samples exploded when the carbon content fell below about 0.8 pct. They concluded that the rate-limiting step was the transfer of oxidant to the gas-metal interface. A model based on this rate-limiting step predicted decarburization rates within a factor of two of those experimentally observed. The explosion of the samples was attributed to a shift in rate-controlling step from gas-phase mass transport to transport of carbon dissolved in the metal. L. A. Baker and R. G. ward6 and R. Baker7 used freely falling droplets to investigate oxidation kinetics. In both papers, the authors speculated that flame fronts may have been partially responsible for the lack of better agreement between experiment and theory. Swisher and Turkdogan8 oxidized liquid iron having an initial carbon content of 0.97 pct with CO-CO2 and CO-C02-Ar mixtures at 1580°C. They concluded that a surface reaction was the rate controlling step. Iron-silicon alloys have been oxidized by R. Baker7 and Filipov and Martynov.9 R. Baker 7 also studied iron-carbon-silicon alloys falling as liquid droplets through oxygen. He found that the rate of both carbon and silicon oxidation varied inversely with the drop radius. When the initial silicon concentration was greater than 6 pct, the samples cooled during their fall. Manganese oxidation has been studied by R. Baker,7 and by Filipov and Martynov.9 ward10 investigated the loss of manganese from liquid iron under vacuum. He found that mass transport of manganese vapor was rate limiting in argon atmospheres of 0.02 torr to 700 torr pressure. Iron-sulfur alloys were desulfurized with H2-He and H2-Ar mixtures by Peters et al.11 A model based on the transport of H2S from the gas-metal interface into the bulk gas gave fair agreement between the predictions of the model and the experimental results. EXPERIMENTAL TECHNIQUE Essentially, the technique consisted of using helium-oxygen gas mixtures to oxidize levitated samples of liquid binary and ternary iron-base alloys. The fused silica reaction tube is shown in Fig. 1. The coil design is similar to that of L. A. Baker et al.4&apos;5 A Tef-lon-sheathed, ferritic stainless steel lifter (B) and an alumina pedestal (C) were used to support the sample in the coil prior to levitation and for the recovery of the sample. Samples were inserted into

Jan 1, 1970

By R. J. Stoehr, F. Howell

Since the ore mined in the Grants-Ambrosia Lake uranium area is taken from a water-saturated sandstone formation, part of the milling operation includes a drying process. The authors discuss the merits and disadvantages of two methods: natural drying and mechanical gas-fired drying; operating and cost data are included. In the Grants-Ambrosia Lake uranium area, approximately 7000 tons of ore are mined each day from a water-saturated sandstone formation. This ore is sampled and treated at four separate milling operations. Prior to the design and initial construction of the milling facilities, very little was known as to the physical properties of the ore which would be handled in the sampling and crushing facilities at the mills. All four mills initially were constructed without ore-drying facilities. As mining proceeded, it was determined that, even after drying the ore in place by use of drainage development underground, the moisture content of the ore as hoisted averaged approximately 18 pct. Actually, some of the mines produced ores which resembled cream-of-wheat in character and had a moisture content in excess of 24 pct. Each of the four mills had a differently designed sampling and crushing plant; therefore, the moisture content of the ores had varying adverse effects upon the operation of the plants. It was determined after some experience that most of the sampling and crushing facilities could not economically handle ore if the moisture content was greater than 10 pct—one operator considers 12 pct moisture as a maximum. In all of the plants, moisture content over 8 pct increases costs to some extent. In addition to the added sampling and crushing costs, some of the mills were located 15 to 20 miles from the mines and the high moisture content of the ores increased the haulage costs from the mine to the mill. It was generally conceded that it was necessary to employ some method to reduce the moisture content of the ore prior to sampling. Several methods were considered: 1) natural drying at the mine site, 2) mechanical gas-fired drying at the mill site, 3) mechanical gas-fired drying at the mine site, 4) radiant heating on concrete clabs, and 5) infrared shed drying. After preliminary investigation all possibilities but natural drying and mechanical gas-fired drying at the mill site were eliminated. NATURAL DRYING A cooperative feasibility study was conducted on the natural drying method. This study indicated the following: 1) During summer months May through September, ore piled 4-ft deep would dry from +20 to +10 pct HzO in 30 days with no mechanical turning. 2) In the first four days after piling a reduction of 5 to 7 pct total moisture content was accomplished by drainage and absorption of the water into the underlying ground on which the ore was piled, providing the ground surface absorption rates approached 10 gal per sq ft per day. After the first four days the decrease of moisture caused by drainage was practically nonexistent. 3) In the summer months drying by evaporation amounted to approximately 0.1 pct decrease in total moisture per day and mechanical turning of the ore could increase this as much as three times. 4) Climatic conditions of the area indicated that: a) Air temperatures averaged 64&apos; May, June, July, August, September; 41" October, November, December, March, April; 31" January, February. b) Average rain fall was 10 in. with 40 pct of this occurring during July and August. c) Only on very rare occasions were there over five consecutive days with below freezing temperatures. d) The annual evaporation rate was approximately 75 in. On the basis of this study, two of the mill operations decided to attempt to meet the moisture specifications by natural drying supplemented by mechanical turning. The other two operations decided upon rotary gas-fired drying at the mill site. The natural drying method has been quite successful in practice. The ore running approximately 18 pct moisture is trucked from the head frame and piled in rows about 6 ft wide, 3 1/2 ft deep, 5 feet apart during the months of May through September. In approximately 30 days this ore will

Jan 1, 1961

By A. V. Bradshaw, R. I. L. Guthrie

The behavior of large bubbles in the size range 4 to 25 cm3, rising through molten silver, has been studied. It was found that rising velocities were equivalent to those in aqueous systems of low viscosity. Mass transfer coefficients for oxygen bubbles dissolving in silver were found to be 0.036 ± 0.007 cm sec-1, being close to those predicted for transfer through the front surface of the spherical cap bubble only. It is suggested that the surface active nature of oxygen in silver could account for the relatively low coefficients obtained. MANY metallurgical processes involve interactions between gas bubbles and liquids. Examples include the removal of carbon monoxide in Open Hearth Steelmak-ing, the removal of sulfur by blowing air through copper matte during converting, and the removal of hydrogen from steel during vacuum degassing or inert gas flushing. The steps involved in such refining processes include; transport of the dissolved species to the bubble interface, adsorption and chemical reaction of the species at the interface, desorption of product molecules from the interface, and transport of product gas into the bulk gas phase of the bubble. It has been concluded1 that all the interfacial steps involved proceed so rapidly at steelmaking temperatures that transport of the solutes, present in the metal, become the important rate controlling factors provided nucleation phenomena are not restrictive. The O-Ag system was chosen for the investigation into gas bubble-molten metal interactions due to the relatively high solubility of oxygen that enables rates of oxygen transfer to be measured from changes in bubble volume. Other advantages of this system include the absence of a stable oxide phase at an oxygen pressure of 1 atm and the relatively low melting point of the metal which permits the use of a metallic container, providing that it is resistant to oxidation. In those metallurgical processes where bubbles have an important influence, bubble volumes are usually greater than 5 cm3. For this reason the present study relates specifically to single large bubbles of oxygen rising in silver. These bubbles adopt the characteristic spherical cap shape similar to that shown in Fig. 1 for a 30 cc bubble rising in water. After an initial investigation to determine the velocities of inert (nitrogen) bubbles rising in molten silver, experiments were carried out with oxygen and the rates of mass transfer between the oxygen bubbles and the silver were measured. EXPERIMENTAL Apparatus. The apparatus, Fig. 2, for containing molten silver, was constructed from "Nimonic 75" Alloy (75 pet Ni, 20 pet Cr, 5 pet Fe, Mn) and provided for the release of single bubbles from an hemispherical cup, situated at the bottom of the column. The cup was turned by translating the rotation of the drive shaft through 90 deg. This was accomplished by the use of a bevelled gear system, and a smooth drive was provided by the lubricating action of the silver on the gears. Since reliable high temperature seals at 1000°C were found to be impracticable, the filling and drive shaft tubes were extended outside the 3.5 kw resistance wire tube furnace, where connections were made using easily accessible O-ring seals. The apparatus remained gas tight to the atmosphere at pressure differentials far in excess of those used. The filling tube was connected via a small bore tube to the differential pressure transducer. Gas could be bubbled into the inverted cup from two i-in. tubes which passed down the inside of the column to preheat the gas. The temperature of the silver was maintained at 1020°C during all experiments. Measurement of Bubble Volume. In order to calculate mass transfer rates, it was necessary to obtain a continuous record of the bubble&apos;s volume during its passage through the column of molten silver. The method adopted for measuring the bubble volume involved closing off the top gas space to the atmosphere prior to each experiment, and recording the variation in gage pressure of this space during the formation and rise of the bubble. Since any change in bubble volume results in an equal change in top space volume, Boyles Gas Law may be applied (for isothermal con-

Jan 1, 1970

By D. E. Light, J. Y. Somnay

The use of alkyl acid phosphates and their alkali salts as collectors for the uranium minerals brannerite and uranothorite was investigated. In particular a detailed flotation study was carried out using isooctyl acid phosphate as a promoter. Tests were conducted on an Elliot Lake ore analyzing 0.11% U 3 O 8, chiefly as brannerite, and approximately 9% pyrite. Pyrite was floated with conventional reagents; the flotation of brannerite from the sulfide tails was studied to determine the optimum pH and pulp density to employ with isooctyl phosphate. 4 uranium recovery of over 90% was possible with a selectivity index of 8.95 when these tails were floated at 17% solids and a pH of 1.7. The effect of various modifying agents was also investigated. Aluminum sulfate, lactic acid and sodium silicate improved the selectivity of collection yielding selectivity indices of 9.5 to 11.5. Ferric chloride was found to be a depressant for brannerite. A Bancroft ore which analyzed 0.13% U308, and contained uranothorite was also amenable to flotation using isooctyl acid phosphate. The composite uranium concentrate obtained assayed 0.41% U308 at a recovery of 95.3% and a ratio of concentration of 3.24. Previous investigations1,2 on the flotation of brannerite, pitchblende, uraninite and/or uranothorite from various Canadian ores showed that fatty acids, including oleic acid and tall oils, petroleum sulfo-nates and alkyl acid phosphates, were suitable collectors for these uranium minerals. Additional work carried out by the Mines Branch in Ottawa on brannerite ores from the Elliot Lake area3 used the tall oil Acintol FA-1, or FA-2, as a collector. A recovery of 92% of the uranium in a concentrate which contained about 55% of the weight and assayed 0.2% U3O8 was obtained from a feed of 0.1% U308 in this latter instance. Eigeles et a1.4 carried out flotation on pitchblende ores and found that the most promising results were obtained with alkyl acid phosphates and their alkali salts as collectors. Within the homologous series of alkyl phosphates, the best flotation characteristics were displayed by isooctyl phosphates. Further, isooctyl phosphate derivatives were much less sensitive to hardness forming salts than oleic acid, enabling all flotation tests to be made with tap water. This paper describes tests employing alkyl acid phosphates for the flotation of ores containing brannerite and uranothorite. The flotation work described herein was conducted in conjunction with the development of a leaching process for Elliot Lake, Ontario, brannerite ores. In this process pyrite in the ore was concentrated by flotation and roasted, providing sulfur dioxide which was used to produce sulfuric acid in situ in a liquid-solid extraction process. A 40% conversion to sulfuric acid was indicated at a leaching temperature of 80°C; this resulted in the extraction of 93% of the total uranium after a contact period of 6 hr. A rotary kiln was used as a leaching vessel. Preconcentration by flotation was studied in conjunction with the above process to reduce the bulk of solids for leaching and, consequently, capital expenditure. The materials and methods used in this study will be described initially. Then the results will be presented in two sections, the first dealing with the brannerite ore, and the second with the uranothorite. Finally an economic analysis of the results on the brannerite material will be made. MATERIALS AND METHODS The two ore samples examined were from uranium-producing mines. One was a brannerite ore, a uraniferous quartz pebble conglomerate from the Elliot Lake area, which contained 0.11% U3O8, 4.3% S and 4.5% total Fe. Mineralogical studies of similar samples indicated the presence of quartz, microcline, sericite, pyrite and minor quantities of rutile, pyrrho-tite and zircon. The other ore was from a biotite-rich pegmatite in the Bancroft area; feldspar, quartz and biotite formed the major gangue components. Uranothorite was the principal uranium mineral; the head assay was 0.13% U 3 O 8. Preparation of Feed: The ores were crushed to —10

Jan 1, 1963