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By Wallace N. Thomas

The present interest in large diameter grinding mills and the rapidly rising cost of the drive in proportion to the cost of the mill establishes a need to explore the drive system in detail. The drive for a seven to eight thousand horsepower mill will cost from 1350 thousand to $600 thousand which represents nearly half the total cost of the mill package, and requires as much building space as the mill proper. Some of the drive components require a longer time to manufacture and the installation time and costs are equal to those for the mill. It is apparent that the drive has become a dominant factor in the overall mill design consideration. A new plant requires a tremendous investment in both time and money. With the high degree of competition in the mining industry, low capital cost is an exceedingly important factor in the development of a project. It is just as important, however, to insure that the equipment is going to perform satisfactorily for the anticipated life of the project without adding unplanned operating, maintenance and replacement costs. This is the position in which the engineer or designer usually finds himself and is really one of his primary functions -- establishing a realistic compromise between cost and performance.

Jan 1, 1969

By R. W. Smith, K. H. Lee Discussion by Fred C. Bond

Fred C. Bond (Tucson, Ariz.) — This is a valuable paper presenting much well directed research testing. It describes a practical method by which the long and relatively accurate Bond closed-circuit grindability can be adapted to a known ore so that results of comparable accuracy can be obtained on the same ore from much shorter batch grinding tests. This can be very useful in control work. In large mills a routine batch grinding test on the head sample can be made each day, or even each shift, to check grinding performance by comparison of the work index from each mill grinding section with that obtained from testing. However, it would be well to re-standardize the batch test against a Bond test, perhaps once a week at

Jan 1, 1969

By D. C. Seidel, E. F. Fitzhugh

The Colorado School of Mines Research Foundation has developed a hydrometallurgical process for recovering nickel from oxidized ores, including both the iron-rich laterites and magnesium-rich, soft silicates. Known as the HSO-HTCP (Hydrothermal Sulfidization Oxidation-High Temperature Cementation in Pulp) Process, the system consists of feed preparation, sulfidization, oxidation, precipitation (cementation), and calcination and melting. This paper deals primarily with the sulfidization and oxidation phases of the process. Nickel sulfide ores lend themselves readily to concentration before smelting or pressure leaching, but neither of the major oxidized ore types — the iron-rich laterites and magnesium-rich, soft silicates-has been directly concentrated. Upgrading of crude ore in current practice is limited to cobbing lumps of the harder, lower grade rock (protore) from the softer, enriched silicate ore, because only a small percentage of the nickel in these ores occurs in discrete, contrasting mineral particles. There is no apparent mineralogical contrast in the superficial, iron-rich lateritic ores and, in fact, there is no firm assurance that the nickel atoms are within the lattices of the limonite minerals, or else irregularly adsorbed on the limonite. Within underlying, "rotten rock" silicates, occasional veinlets of gamierite and related nickeliferous silicates are found.' The gamierite veinlets, however, are only incidental, and the majority of the nickel atoms occur as erratic replacements of magnesium atoms in the micaceous chlorites of the ore mass. Pyrometallurgical processes account for nearly all the nickel currently being recovered from oxidized ores. Plants in New Caledonia, Oregon, Japan, Brazil and Greece smelt the ores to make ferronickels or a sulfide matte,2 and the ammoniacal leaching3 at Nicaro, Cuba, is preceded by a reducing roasL4 The only fully hydrometallurgical installation has been the politically ill-fated Freeport Nickel Co. enterprise, and this process was limited to lateritic ores.5p6 A hydrometallurgical technique which might handle both laterite and the typically richer silicate ores has been an enticing goal. The technique described here was developed at the Colorado School of Mines Research Foundation, Inc. on behalf of the Republic Steel Corp. It uses sulfur, heat, air and metallic iron to recover nickel from these ores. Inasmuch as the ores are treated as aqueous slurries, the cost of drying a plant feed that normally carried 30% or more moisture is eliminated, and there are no dust problems. Patent applications have been filed by Republic Steel Corp. on the procedures used for getting the metal into solution and on the subsequent recovery without liquids-so l ids separation of the slurry. It is referred to as the HSO-HTCP Process (Hydrothermal Sulfidization Oxidation — High Temperature Cementation in Pulp). THE PROCESS FLOWSHEET The results of various experimental studies have been combined to form the continuous flowsheet illustrated in Fig. 1. This flowsheet serves as a general pattern showing the sequence of the operations which include: (1) feed preparation; (2) sulfidization; (3) oxidation; (4) precipitation (cementation); and (5) calcination and melting. This paper deals primarily with the sulfidization and oxidation phases of the process. Feed preparation: In general, the silicate ores can be considered as earthy rather than hard, and preparation might be carried out before the addition of water in a trommel, or with water in a scrubber or log washer. This breaks up the earthy particles, allowing the hard lumps to be separated by screening. The oversize material from most ores is relatively barren and may be discarded. If there is occasion to control the iron-magnesium ratio in the plant feed, laterite, which normally breaks up readily into fine sized particles, and silicates are mixed in suitable proportions. The fine product slurry from the initial steps is mixed with elemental sulfur and fed to a conventional ball mill, although the amount of actual grinding that takes place is relatively small. The object of milling is to complete the disintegration to natural particle size and to produce an intimate mixture of the ore and elemental sulfur. This pulp, which is almost entirely -200 mesh, has a pH of about 7.0 and normally can

Jan 1, 1969

Jan 1, 1969

By H. W. Lang

The Bureau of Mines conducted an investigation to observe the effect of cetane improvers upon nitrogen oxides concentration in diesel exhaust gas. Amyl nitrite and amyl nitrate were used as additives to the fuel used in a four-cycle, single cylinder type test engine. It was concluded that nitrogen oxide concentrations were not enhanced at fuel-air ratios above 0.03 pound of fuel per pound of air.

Jan 1, 1969

By P. Somasundaran

Flotation of minerals has usually been discussed in terms of solid-liquid interfacial phenomena. This paper discusses the relative importance of phenomena such as collector adsorption at other interfaces formed between the bubble, liquid and solid. Adsorption of collector ions of various chain lengths at liquid-gas and solid-gas interfaces has been obtained. The data have been analyzed under conditions corresponding to those of flotation to show the significant role of collector adsorbed on the bubble surface in determining the bubble-mineral attachment required for flotation, and consequently to suggest consideration of this role in the development of better flotation conditions. Vacuum flotation of quartz with alkyl ammonium acetate reported in the foregoing paper1 showed that the collector chain length has an effect on flotation even at concentrations below those necessary for hemi-micelle association of the hydrocarbon chains at a solid-liquid interface. This chain length effect might be explained by the following arguments: Hydrocarbon chains find it energetically favorable to be in a medium of low dielectric constant. Considering the possibility of an iceberg structure at the solid-liquid interface, such a structure would produce a region of lower dielectric constant at the solid-liquid interface than in the liquid phase, because the dielectric constant of ice is 2 to 3,2 while that of water is 80. Depending on chain length, this difference will certainly cause even individual ions to adsorb in higher quantities at the solid-liquid interface. Another mechanism to consider is the possible formation of dimers, trimers, etc and chain length would influence this formation. But, above all, the chain length effect on flotation at concentrations of low adsorption at the solid-liquid interface could be due to the significant but often-neglected role of the collector adsorption at the bub- ble surface. Collector ions or molecules are adsorbed both at the solid-liquid interface and the liquid-gas interface. Below the concentration for hemi-micelle association at the Stern plane adjacent to the surface, the bulk of the collector ions adsorbed at the solid-liquid interface are in the diffuse part of the double layer. If such systems, where there is a gas bubble coming in contact with the solid surface, are to achieve some degree of electroneutrality, those collector ions would have to migrate from the diffuse part of the double layer to the region directly adjacent to the surface during the induction period when the bubble is making contact with the solid. The time necessary for this migration would contribute to the induction period required for creation of the solid-gas interface. It seems reasonable that the induction period could be reduced sufficiently for flotation to occur if these collector ions were carried to the surface by the bubble. In an attempt to ascertain whether or not the bubble could possibly have sufficient collector ions at its surface to meet the requirement mentioned above, the adsorption density of the collector ions at the liquid-air interface was determined. For this purpose, the surface tension of alkyl ammonium acetate solutions was determined as a function of concentration. Adsorption densities of the collector at the liquid-gas interface were calculated using the Gibbs adsorption equation: where y is the interfacial tension and ri and pi are the adsorption density and the chemical potential, respectively, of the chemical species, i. Using the convention that the adsorption density of water at the interface is zero, the following relationship is obtained for the liquid-gas interface where lg refers to liquid-gas interface and RA+ refers to the alkyl ammonium ions. For dilute solutions, rf^-wri^&rfwW [3] where C is the concentration of the collector ions in solution. l?:: can now be evaluated using Eq. 3 and surface tension measurements.

Jan 1, 1969

By W. H. Yarroll Discussion by W. A. Griffith

W. A. Griffith (Head, Research Department, Phelps Dodge Corp., Morenci, Ariz.) - It is gratifying to see the increasingly common use of classical statistical procedures by metallurgical researchers. Mr. Yarroll has given excellent illustrations of the utility of multiple correlation analysis of complex metallurgical data. Our experience in applying these procedures to historical plant operating data has differed, however, from that which he suggests. The uninitiated frequently assume that the volumi-

Jan 1, 1969

By Harry Perry

A technology for producing liquid fuels from oil shale at prices competitive with crude oil prices is a necessary but not exclusive prerequisite for the development of a shale oil industry. Many other factors will affect the timing and the rate at which oil shale is commercially developed. Among the more important are: governmental policy concerning oil shale and oil resources (including the Outer Continental Shelf) that are under Federal control; oil import policy; Federal taxation of shale oil production including depletion allowances; regulatory practices; competition from other energy sources, both synthetic and natural; Federal treatment of factors affecting competing energy resources; and present legislation under which the public resources must be leased. Significant changes in any of the foregoing factors could have a controlling effect on the timing and rate of oil shale development. The effect of changes in each of these factors is evaluated.

Jan 1, 1969

By P. S. Kotval

THE nominal composition of "hconel" alloy 718 is 53 pct Ni-19 pct Cr-19 pct Fe-3 pct Mo-5 pct Cb-0.8 pct Ti-0.6 pct A1-0.05 pct C. The nature of the fine strengthening phase in this alloy has been open to debate. iseelstein' has identified the strengthening phase in the matrix of "Inconel" alloy 718 as a colum-bium-rich fcc y' precipitate. Wagner and Hall2 have noted that the metastable y' precipitate overages to an orthorhombic Ni3Cb precipitate which manifests itself as an acicular phase. These authors thus clarify Kaufman and Palty's earlier suggestion3 that the strengthening phase is orthorhombic NisCb. Wagner and Hall's review also reports work by cometto4 which suggests that the fine strengthening phase is not fcc / but bct with a Ni3V type structure and based on the Ni3Cb composition. Kir man and warringtons have shown by analysis of electron diffraction patterns that the metastable strengthening phase in a 55 pct Ni-15 pct 0-25 pct Fe-5 pct Cb alloy is bct and based on the Ni3Cb composition. Raymond~ has provided electron diffraction evidence which indicates that "y'" in "Inconel" alloy 718 is bct in structure. This note presents unambiguous data on the structure of the strengthening phase in "Inconel" alloy 718* ihe samples of this alloy were provided by courtesy of the ASTM task group on phase identification in 'superalloys. after prolonged aging. The electron diffraction patterns presented show that strengthening phase is not y' but bct as was proposed by cometto,' supported by Raymond,~ and identified by Kirman and warringtons in a similar system. Fig. 1 shows a selected-area diffraction pattern taken from a thin foil of "Inconel" alloy 718. The sample had received a final aging treatment of 1118 hr at 1200°F to precipitate the strengthening phase in the matrix. Fig. 2 is a schematic representation of the features in the diffraction pattern. The matrix orientation is (0i2)~,, as is shown by the indexed zone in Fig. 3. Figs. 4, 5, and 6 illustrate that the pattern, Fig. 1, is composed of three bct zones, viz., (0i4), (2i0), and (i01), respectively. These three zones correspond, respectively, to the alignment of the c axis of the bct unit cell with the [001], [loo], and [OlO] directions of the fcc matrix and serve to illustrate the fully coherent relationship of the precipitate structure with the matrix. The streaking of certain reflections is also consistent with the above orientation relationship. The interpretation of the diffraction effects presented here shows the metastable strengthening precipitate in "Inconel" 718 alloy to be bct in structure and demonstrates that it is not an ordered fcc y' phase.

Jan 1, 1969

By K. M. Myles

The vapor pressure of palladium over a series of Rlz-Pd alloys has been measured by the torsion-effusion method. The thermodynamic properties of the alloy system at 1575=K have been calculated from the vapor pressure data. The activities and the free energies of formation exhibit large positive deviations from ideal behavior. The enthalpies of formation are endother-mic. The entropies of formation are positive and larger than the ideal entropy of mixing. All of the thermodynamic properties suggest that a strong tendency toward phase separation exists in the solid solutions. The possible origin of the phase instability and the various factors that influence the thermodynamic properties are discussed. RECENT studies of the thermodynamic properties of alloys of palladium with nontransition elements have indicated that a significant contribution to the enthalpy of formation is related to the redistribution of the conduction electrons upon alloy formation.'-' The present work was undertaken to ascertain the importance of this contribution in Pd/transition-metal alloys. The Rh-Pd system was chosen for this investigation for several reasons: 1) The thermodynamics of the system were unknown. 2) Rhodium and palladium are completely soluble at high temperatures; below 1118OK the solid solution becomes immiscible.', 3) The difference in magnitude between the vapor pressures of rhodium and palladium permitted the use of an existing effusion apparatus. 4) Additional information was known about the alloy system that would facilitate the interpretation of the thermodynamic results. EXPERIMENTAL PROCEDURE The thermodynamic properties of the Rh-Pd alloy system were calculated from the vapor pressure of palladium over solid palladium and over several solid Rh-Pd alloys. The vapor pressure was measured by means of the torsion-effusion apparatus that has been described previously. In this method, an effusion cell is suspended from a tungsten filament inside a high-temperature furnace. Two orifices are located eccentrically such that the effusion of the vapor creates a rotational torque in the filament. The angle of rotation is directly related to the total vapor pressure within the cell. As the vapor pressures of rhodium and palladium are approximately five orders of magnitude apart," the total vapor pressure was considered to be effectively equal to the equilibrium vapor pressure of palladium. The effusion cells were made from high-purity alumina since auxiliary experiments indicated that essentially no reaction occurs between alumina and solid Rh-Pd alloys. Unfortunately, because the orifices were irregular, an accurate calculation of the Free- man-Searcy correction factors" could not be made. The constants were determined in an independent experiment where the vapor pressure of copper, as measured in the alumina cell, was compared with an accurate value of the vapor pressure, which had been determined previously.4 Depletion of palladium from the surfaces of the specimens was minimal as the deflection of the cell remained constant, for at least 15 minutes, at each of the experimental temperatures. Lattice parameter measurements of the postrun alloys also indicated that no changes in the composition of the surfaces had occurred. The alloys were prepared by arc melting the requisite amounts of the 99.99 pct pure elements. The four most palladium-rich alloys were remelted in a levita-tion furnace since complete melting of the components had not occurred in the arc furnace. All of the alloys were subsequently homogenized at elevated temperatures in sealed alumina thimbles. After heat treatment, the alloys were analyzed chemically and were in essential agreement with the nominal compositions. The thermal histories and nominal compositions of the alloys are given in Table I. Lattice parameters of the heat-treated alloys were computed, by means of the method described by Mueller et a1. ,I2 from X-ray diffraction powder patterns obtained with filtered copper radiation in a 114.6-mm-diam Straumanis-type Debye-Scherrer camera. The results, which are tabulated in Table I, exhibit a slightly greater negative deviation from Vegards' law than the values reported by Raub et al.13 The diffraction lines were sharp and well-resolved and thus indicated that the alloys were homogenous. RESULTS The logarithms of the individual values of the vapor pressure of palladium were fit, by the least-squares method, as a linear function of the reciprocal of the absolute temperatures. The constants of the equations are given in Table I along with the temperature range over which the data was accumulated. The latent heat of vaporization at 298.15"K for pure palladium, calculated by the third-law method,14 showed no systematic temperature dependence. The average value of 88,920 * 20 cal per g-atom agrees favorably with the average of the results obtained in the most reliable previous investigations.15"19 The activities of palladium were computed from the vapor pressure data at 1525', 1575", and 1625OK. Consistent with the mass spectrometric study of the atomicity of palladium vapor,lg the vapor was assumed to be monoatomic. The activities of rhodium were determined by integrating the Gibbs-Duhem equation with the aid of the a function.20 In the calculations, the activities of the pure solid metals were assigned the value of unity. From the activities, the partial and integral free energies, entropies, and enthalpies of formation at 1575° K were computed; they are assembled in Table 11.

Jan 1, 1969

By H. Biloni, R. Morando

The surface structure and substructure of Al-Cu alloys solidified as conventional ingots and under particular conditions such as those used by Bower and Flemings are studied. The influence of lampblack coating on the mold walls is especially considered and the results compared with those obtained in copper and graphite molds where no coatings exist. When high heat extraction conditions exist the observations show that mechanism of copious nucleation is responsible for most of the chill zone. When the heat extraction through the mold walls is low, a coarse grain structure with dendritic morphology arises, with a size that depends on the degree of convection present, analogous to that analyzed by Bower and Flemings. In both cases the effect of the convection on the macroscopic and microscopic appearance is discussed. The ingot macrostructure consists of one or more of three zones: "chill zone", "columnar zone", and central "equiaxed zone". The mechanism of the columnar-equiaxed transition has been subject of considerable interest and at present at least three theories exist about the formation of the equiaxed region: 1) the constitutional supercooling theory1 maintains that the equiaxed crystals nucleate after the columnar zone has formed, as a result of the constitutional supercooling of the remaining liquid; 2) chalmers2 pointed out, however, that there were several objections to this proposal, and that consideration should be given to the possibility that all the crystals, equiaxed as well as columnar, originated during the initial chilling of the liquid layer in contact with the mold; 3) Jackson et aL3 and O'Hara and ~iller~ suggested that a remelting mechanism of the dendrite arms is responsible for the formation of the equiaxed region. After the work of Cole and Bolling and other authors6 it became evident that convection (natural, reduced, or forced) plays a very important role in the transition from columnar to equiaxed and on the size of the resultant equiaxed structure. Until recently the accepted explanation of the chill zone was that it occurs as a result of copious nucleation in the liquid layer in contact with the mold walls.798 The columnar region is a subsequent result of the growth of favorably oriented grains and, as a result of a selection mechanism studied by Walton and Chalmers,9 elongated grains with marked texture are formed. Recently, however, Bower and Flemings" using an ingenious laboratory experiment introduced the idea that the "copious nucleation" mechanism is not responsible for the formation of the chill zone and that the presence of convection, introducing some form of "crystal multiplication", plays a decisive role in the formation of the chill zone. Unfortunately, it is important to consider that for their conclusions Bower and Flemings extrapolated the results obtained in their special experiments to the case of conventional ingots, and that these authors only analyzed the macrostructures of the specimens. Let us consider the work by Biloni and chalmers" concerning predendritic solidification. These authors were able to show that a study of the segregation substructure of A1-Cu gives information about the nucleation and growth of crystals formed in contact with a cold surface. A spherical predendritic region characterizes the first part of every grain nucleated in contact with the surface as a result of the chill effect. The aim of this paper is to elucidate through the observation of the segregation substructure the conditions under which (in the Bower and Flemings type of experiments and in conventional ingots) either the nucleation or the multiplication mechanism gives rise to the structure in contact with the mold walls. I) EXPERIMENTAL TECHNIQUES The experiments were performed on two alloys: Al-1 wt pct Cu and A1-5 wt pct Cu. The purity of the aluminum was 99.99 pct and the copper 99.999 pct. The results obtained with both alloys were similar. In the Bower and Flemings type of experiments the apparatus employed to obtain rapid solidification against a surface was similar to that used by those authors. The liquid was drawn by partial vacuum into the thin section mold cavity. Plate casts were 5 cm wide and usually 7.5 cm high. The thicknesses of the cast were 0.1 and 0.3 cm. Two different materials were used for the mold, copper and nuclear-grade graphite. The internal mold surfaces were polished and left uncoated for some experiments. In other experiments, the copper or graphite surface was coated with a thin film of lampblack material. In some of these particular experiments one of the mold walls was left with an uncoated region (usually in the form of a cross). The conventional ingots were cast in graphite or copper molds. In different experiments the mold walls were sometimes uncoated or coated with lampblack material. The results obtained in conventional and Bower and Flemings copper molds were compared with those obtained with copper molds coated with a very thin film of graphite; the results obtained were essentially similar. The size of the conventional ingots was 5 cm diam and 7 cm high in all cases. The cast surfaces produced by the Bower and Flemings type of experiments and conventional methods were observed macroscopically and microscopically without any metallographic preparation. As Biloni and Chalmers showed," the observation of the chill surface can give considerable information about the structure and segregation substructure.

Jan 1, 1969

By S. K. Tarby, V. S. Robinson III

A number of experimental determinations of the vapor pressure of liquid silver have been reported in the literature. 1-8 This communication presents additional data for the vapor pressure of liquid silver measured in the temperature range of 1450° to 1600°C and summarizes the results of previous investigations. The results reported here were obtained as part of a

Jan 1, 1969

By H. E. Cline, J. L. Walter

Grain boundary sliding and migration were studied in pure aluminum bicrystal and polycrystal samples with two-dimensional grain structure. Scratches, 50 P apart, were used for measurement of sliding and migration distanceso. Samples were deformed at constant rate at 315C and events recorded continuously on wrotion picture film. Electron micrograPhs of boundary-scratch intersections were obtained. Yield and flow stress values were measured. The sequence of sliding and migration events for a three-grain junction is described in detail. Sliding depended only on the resolved shear stress imparted to the boundary. Sliding was accowmodated by formation of shear zones in grains opposite triple points and adjacent to curved boundaries. These shear zones provided the driving force for grain boundary migration. Migration caused rumpling of the boundaries, decreasing the sliding rate. Sliding and migration generally began at the same time, occurred simultaneously and ended at the same time. In the bicrystal, sliding and migration rates were proportional. Initial sliding rules of 5 X joe cm per sec. were measured for the polycrystal and bicrystal samples. These sliding rates agree wilh the internal friction experirnents of K;. The observations seem consistent with a viscous boundary sliding nzechanism. GRAIN boundary sliding is the translation of one grain relative to its neighbor by a shear motion along their common boundary. Sliding is thought to be an important mode of deformation at elevated temperatures and at low strain rates such as prevail in creep,' and perhaps in the area of superplastic behavior.2"4 Although much work has been done to investigate grain boundary sliding, the effort has not led to the identification of a mehanism. KG showed that grain boundaries in aluminum exhibit a viscous nature under very small displacements of internal friction measrements. Various dislocation mechanisms have been proposed but are without conclusive experimental support. Attempts to relate sliding to 6's viscous boundaries have been unsuccessful in that measured rates of sliding are always several orders of magnitude lower than KG'S results would predict.= In bi crystals7and polycrystalsR of aluminum tested under constant load, the grain boundary sliding was found to be proportional to the total creep elongation which indicated that sliding might be controlled by deformation of the grains. Shear zones were observed to extend beyond grain boundaries at triple points to accommodate the sliding.8 Surface observations brought forth the opinion that sliding and migration occurred alternately, in sequence.' Measurements of sliding at the surface have been criticized because they might not be representative of the interior of the sample. Generally speaking, it seemed that much of the previous work and knowledge was based on observations made at relatively low magnification and examination of samples after deformation had been accomplished. Thus, it was the purpose of the present study to continuously record, at high magnification, the events occurring during the deformation of pure aluminum. Samples with two-dimensional grain structures were used to simplify interpretation of the results. The sliding and migration of small areas of many samples were continuously recorded by time-lapse motion pictures. Replicas of the surface were used to provide high-resolution electron micrographs. These observations, coupled with tmsile strength data, provide sufficient information to arrive at an understanding of the phenomenon. EXPERIMENTAL PROCEDURE An ingot of 99.999 pct A1 was rolled to sheet, 0.127-cm thick. Tensile specimens, with a gage length of 0.85 cm, were machined from the sheet. Bicrystal tensile specimens, of the same dimensions, were spark cut from a large bicrystal ingot. The grain boundary was oriented at 45 deg to the tensile axis. The surfaces of the tensile samples were ground flat on fine metallographic paper and were then electropolished in a solution of 75 parts absolute alcohol and 25 parts of perchloric acid. The solution was cooled in an ice-water bath. Using a weighted sewing needle suspended from a small pivot on a precision milling machine, a grid of fine scratches, 50 p apart, was scribed on one surface of the sample. The polycrystalline samples were then annealed in hydrogen for 15 min at 350" to 400°C to produce a two-dimensional grain structure of about 0.2-cm average grain diameter which would not undergo further growth at the test temperature, 315OC. Examination of both surfaces of the samples showed that the grain boundaries were perpendicular to the surface of the polycrystal and bicrystal samples. A hot-stage tensile machine was constructed for use with an optical microscope as shown in Fig. 1. The specimen is shown mounted in the grips. The grips ride in V-ways so that the sample can be mounted without damage. The rear grip is free to slide so that when the sample expands during heating it is not put under a compressive stress. When the grips and samples are at temperature, the rear grip is locked in place by two set-screws. The other grip is connected to a synchronous drive motor which, through a worm gear and a fine-threaded rod, deforms the

Jan 1, 1969

By P. C. Good

The Bureau of Mines conducted a laboratory investigation of a sinter-leach method to recover aluminum and fluorine from waste carbon potlining residues from secondary cryolite recovery operations in aluminum reduction plants. After removal of carbon by burning, the residue was sintered at 900° to 1,100° C with silica and N2CO3, then crushed and leached with dilute NaOH solution, dilute Na2C03 solution, water, or water containing residual Na2O which remained in the sinter after reaction and decomposition of Na2CO3. Over 90 percent of the contained aluminum and up to 87 percent of the contained fluorine were extracted from this waste product in the form of a mixed alkaline solution. Treatment of the alkaline solution with CO2 yielded a white precipitate containing 89 percent of the original aluminum and 61 percent of the original fluorine as a mixture of synthetic cryolite and alumina, together with a variable excess of soda.

Jan 1, 1969

By T. G. Sieber, T. D. Tiemann

The extraction of quartz from siliceous iron ores by dissolution in sodium hydroxide solution has been described in detail in AIME Transactions. l923 data reported covered the temperature range from 230-416°F, where a continuous increase in the amount of silica extracted with increase in temperature was found. It is the purpose of this paper to describe some unexpected results of more recent work exploring principally the range of 500600°F where higher rates and greater amounts of silica extraction were antici-p ted. In brief, the experimental procedure consists in digesting the ore under pressure in solutions of sodium hydroxide, filtering the suspension and weighing and analyzing the dried residue for iron content. The amount of extraction is calculated from the weight loss or from the iron analysis of the residue and that of the original ore.

Jan 1, 1969

By James W. Burns

Thin, heavily doped n-type layers of GaSb have been grown on p-type GaSb substrates. Techniques have been developed for the growth of the n-type layers from a tellurium-doped gallium-rich solution. The solution used consists of 95 at. pct Ga and 5 at. pct Sb. The process consists of immersing the p-type wafer in the solution at a temperature slightly above the liquidus temperature, holding briefly to permit dissolution of the substrate surface, then decreasing the temperature to a value slightly below the liquidus to obtain 1 HE resistivity of n-type GaSb varies linearly with applied hydrostatic pressure, while the resistivity of p-type GaSb is insensitive to such pressure.1,2 The growth. Growth from a solution of GaSb in tin will also be described. In either case the substrate is clamped to a shelf at one end of a graphite boat, and immersion of the wafer and subsequent decanting of the solution is accomplished simply by tilting the furnace. The process is useful for the formation of p-n junctions in III-V compounds and has the advantage that the problems normally associated with diffusion of Group VI elements are not present. Layers up to 4.0 mils in thickness have been grown by the process. material therefore should be useful in a hydrostatic pressure-sensing device. A practical hydrostatic pressure sensor, however, requires the fabrication of GaSb sensing elements of several hundred ohms resistance. Attempts were made to prepare such elements by diffusion, taking advantage of the high sheet resistance of the thin diffused layers and depending upon the p-n junction to provide isolation from the base layer. Additionally, thin layers of conductivity type opposite from that of the base layer were pre-

Jan 1, 1969

By C. Dalton, H. L. McGill

The purpose of this study was to develop a method for predicting the time delay created by metering a fluid through an annular restriction with translational motion of the boundaries. This time delay is utilized to control the opening of valves in various down-hole oilfield tools and forms the basis for the "hydraulic jar". The hydraulic jar is used to give upward impact forces to tubing or other tools that become lodged down-hole. The design of these jars has primarily been by trial and error; varying the clearances, fluid viscosities and dimensions of the jar until a satisfactory time delay was achieved. Obviously, a better understanding of the fluid flow characteristics is required to produce designs that are satisfactory and to eliminate the trial-and-error approach. Previous studies of flow in annular spaces were based on constant length of the annular restriction. Any motion of the boundaries of the annular space was confined to a rotational motion, like that encountered in journal bearing design. Consideration of the effect of translational motion of one boundary with respect to the other was necessary in applying this previous work to a time delay device. A prediction method was developed that takes into account this relative translational motion. Equations were developed to predict the relative velocity, the flow rate, and the time delay in a concentric annular space. The effect of eccentricity also was included. Experimental data were obtained and closely correlated with the prediction method. This correlation is presented graphically in terms of predicted and actual relative velocities for various annular clearances and pressure drops. This extension provides design equations which predict the performance of the hydraulic jar, thereby eliminating trial-and-error solutions and reducing the development time required for satisfactory designs. INTRODUCTION The design of down-hole oilfield tools which use hydraulic delay systems based on flow through annular orifices with relative motion of the boundaries is usually a trial-and-error process. The annular clearances, fluid viscosities and dimensions of the mechanisms were varied until satisfactory delay times were obtained. The development of these tools has been expensive, and a better understanding of the characteristics of annular flow with relative motion of the boundaries could result in superior and less expensive designs. The purpose of this investigation was to provide a method of predicting the performance of down-hole tools which use annular flow and, in particular, the performance of a down-hole tool known as the "hydraulic jar". The hydraulic jar is used to free pipe, packers and other tools that become lodged down-hole. The jar, located in the tubing string between the surface and the object which is stuck, releases the object though the repeated application of upward impact blows. The jar is basically a slip joint that is restrained in a collapsed condition until the desired tubing tension has been developed. The slip joint is then released and accelerates rapidly until it shoulders, delivering an impact blow or jar to the object. The delay obtained by metering the fluid through the annulus formed by the jar valve and housing provides the time delay necessary to stretch and apply tension to the tubing or pipe. Fig. 1A gives a schematic diagram of the hydraulic jar and brief details of its operation. The metering of the hydraulic jar begins when the tension force being applied to the jar by the pipe creates a pressure differential across the valve that is approximately equal to the force divided by the displacement area of the valve. This pressure differential induces flow through the annular restriction formed between the valve and housing. The valve moves with respect to the housing as the

Jan 1, 1969

By R. C. Gould, A. M. Skov, L. F. Elkins

Comparison of long term decline in oil production during cyclic waterflooding or pressure pulsing of part of the Driver Unit with steady injection-imbibition flooding in the Tex Harvey area led to large expansion of flood in the Driver Unit on the steady injection basis. While the flood has been successful, the major problem has been attainment of satisfactory oil production rates in most of the wells. Large volume fracture treatments of low capacity wells were unsuccessful in achieving sustained increases in production. A two-section area in the Driver Unit has already recovered 620 bbl of oil per acre by waterflood but other areas have not performed so well. Sun Andres water containing 300 to 500 ppm H,S is sweetened to 0.5 to 1 ppm H,S by extraction with oxygen-free flue gas. This prevents contamination of gas produced in the area and apparently it has reduced corrosion in minimum investment, thin-wall, cement-lined water dktribution systems. Cement-lined tubing in injection wells has mitigated corrosion as effectively as thick polyvinyl chloride films have, and at less cost. Introduction As reported in the literature the Spraberry field of West Texas has presented unusual problems for both primary production and waterflood ing. Earlier information from the Spraberry Driver Unit included conception and evaluation of cyclic waterflooding or pressure pulsing in a nine-section pilot test as an aid to extraction of oil from the tight matrix rock and as a boost to normal capillary imbibition forces An additional 5 years' operation in that area, and performance of expanded steady injection water-flood, now covering a total of 68 sq miles, are reported herein. In addition, since the Driver Unit is one of the largest waterfloods in areal extent in the U. S., many operating experiences are presented for the benefit of engineers concerned with operation of other Spraberry floods or with other waterfloods where this reservoir technology and/or water handling technology may be adaptable in part. These include: (1) attempts to improve producing well capacity through large volume fracture treatments, (2) long-term performance of water treating plants utilizing oxygen-free flue gas to extract H,S from sour San Andres water, (3) performance of thin-wall cement-lined pipe in water distribution systems including comparison between those sections carrying raw San Andres water and those carrying treated water, and (4) comparison of performance of various lining materials and subsurface equipment in water supply and water injection wells. These experiences are reported without regard to whether results are good, bad or indifferent. Since the operations reported are limited to the techniques, materials, and equipment actually used in the Driver Unit, no comparison is possible with results of other approaches used in other Spraberry floods or in waterfloods generally under different conditions. However, an attempt is made to quantify these experiences as much as possible in the space available to permit other engineers to select those parts applicable to eheir problems. Background The Spraberry, discovered in Feb., 1949, is a 1,000-ft section of sandstones, shales and limestones with two main oil productive members—a 10- to 15-ft sand near the top and a 10- to 15-ft sand near the base, having permeabilities of 1 md or less and porosities of 8 to 15 percent. Extensive interconnected vertical fractures permitted recovery of oil on 160-acre spacing from this fractional-millidarcy sandstone, but they made capillary end effects dominant. Primary recovery by solution gas drive is less than 10 percent of oil in place, with most wells declining to oil production of a few barrels per day when reservoir pressures are still in the range of 400 to 1,000 psi. Partial closing of the fractures with declining reservoir pressure is believed to be the cause of such low production rates at these relatively high reservoir pressures. In 1952 Brownscombe and Dyes proposed that displacement of oil by capillary imbibition of water from the fractures into the matrix rock might significantly increase oil recovery from the Spraberry, overcoming otherwise serious channelling of water through the fractures." A pilot test conducted by the Atlantic Refining Co. during 1952 through 1955 indicated technical feasibility of the process; but low oil production rates averaging I5 to 20 bbl/well/D failed to create significant interest in large-scale waterflooding at that time." Humble Oil & Refining Co. conducted a highly successful 80-acre pilot test during 1955 through 1958 with

Jan 1, 1969

By Jonas Svensson

The Grangcold Pellet Process - for which patents have been applied or already granted in a number of countries - uses a hydraulic adhesive such as Portland cement, slag cements, pozzolanic cements, etc., for the production of cold bonded pellets. The idea of using a hydraulic binder for the agglomeration of iron ore fines is not new. Portland cement was proposed as an adhesive for cold bonded iron ore briquettes in patents granted more than 50 years ago (1). In a report on the briquetting of iron ore fines, published in Stahl and Eisen 1959 (2), it is stated that briquettes bonded with Portland cement are used on a small scale at on ironwork in Germany. According to the report, the briquettes showed excellent strength in the blast furnace although their general use was made impossible because they required a long hardening time, during which they are sticky, soft and difficult to store and handle. The Grangcold Pellet "recess has overcome this particular disadvantage by mixing the balls with a suitable amount of the balling concentrate before storing them. The pellets are embedded in the concentrate during storing in such a way that they are isolated from each other and thus prevented from sticking together to form clusters. Thanks to the embedding concentrate, the pellets are subjected to a more or less uniform pressure from all sides which does not deform them. Thus the mixture can he stored in a stockpile or in a silo until the pellets have hardened sufficiently. The concentrate is separated from the pellets by means of screening. The concentrate is returned to the balling operation and the pellets are either shipped to the blast furnace or stored for final hardening.

Jan 1, 1969

By L. H. Van Vlack, T. Y. Tien, R. J. Martin

The phase relationships of the MnTe-MnS system were studied by DTA procedures. There is an eutectic at 810°C with about 10 mole pct MnS-90 mole pct MnTe. An eutectoid occurs at about 710°C with approximately 7 mole pct MnS where the MnTe(NaCl) solid solution dissociates on cooling to MnTe(NiAs) and MnS. There is very little solid solubility of MnTe in MnS. ALTHOUGH MnS may exist in three different crystal forms,' only the NaC1-type phase is stable.2 Above 1040°C, MnTe also has the cubic NaC1-type structure. Below that temperature, MnTe changes to the NiAs-type structure.3 This phase transition is rapid for both heating and cooling. As a result the high-temperature crystal form of MnTe cannot be retained at room temperature. Because MnO, MnS, and MnSe are all stable with the NaC1-type structure, and MnTe has this structure at high temperatures,4 solid solution formation could be expected among these compounds. It is interesting to note, however, that a complete series of solid solutions exist only in the MnS-MnSe system,' and that the solid solution is quite limited in the MnO-MnS system.' The MnSe-MnTe system possesses a complete series of solid solutions at high temperatures with separation at lower temperatures.7 Although ion size may be critical in the miscibility of MnO-MnS, it is quite possible that the bond type plays a more important role with the miscibility of MnSe-MnTe. This would permit us to speculate that the miscibility gap would be extensive in the MnTe-MnS system. EXPERIMENTAL Preparation. The samples were prepared by mixing and compacting MnTe and MnS powders. The MnS was previously prepared through the sulfur reduction of Mnso4.8 The MnTe had been prepared by mixing and compacting double vacuum distilled metallic manganese and high-purity tellurium in stoichiometric ratio modified with 1 wt pct excess tellurium. The compacted powders were put in a graphite crucible which was sealed in an evacuated vycor tube. The free space in the vycor tube was made minimal to reduce the loss of tellurium. The sealed assembly was then heated slowly to about 500° C where the free manganese and tellurium reacted vigorously, melting the MnTe which formed. Only one phase, MnTe, was detected by X-ray powder patterns and metallographic techniques. Each compact of MnTe-MnS was placed in a graphite crucible and then sealed in an evacuated vycor tube. The samples were heated at 1250°C for 4 hr and furnace-cooled. Microscopic examination revealed no third phase beyond MnS and MnTe. A typical microstructure is presented in Fig. 1. Identification. X-ray powder patterns were obtained using 114.6 mm Debye-Scherrer camera and Fe-Ka radiation. Mixtures of cubic MnS and hexagonal MnTe were observed in all of the compositions prepared. No lattice parameter change was noticed among different compositions, indicating no solid solution could be retained at room temperatures between these two end-members. A lattice parameter of 5.244Å for MnS was obtained by the Nelson and Riley9 extrapolation method using the diffraction lines of (h2 + k2 + 12) equal 12, 16, 20, and 24. The values, a = 4.145Å and c = 6.708Å, for hexagonal MnTe were obtained from the (006) and (220) lines in the back-reflection region. These values agree well with the values reported by Taylor and Kag1e.10 Differential Thermal Analysis. A differential thermal analysis procedure was used to determine phase relationships since the high-temperature equilibrium conditions could not be retained for examination at room temperature, even when the sealed samples (~0.5 g) were quenched in water. The samples were sealed in an evacuated 4 mm vycor tube with a recess in the bottom to accept a thermocouple. An Al2O3 reference was similarly prepared and the two placed within a piece of insulating fire brick to dampen spurious temperature changes within the furnace. The furnace was controlled by a mechanically driven rheostat which increased the temperature at a rate of about 15°C per min. Known phase changes in the Pb-Sn system1' and the a-to-ß quartz inversion12 were used for calibration

Jan 1, 1969