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By D. W. Mitchell

INE operators have a choice of several classi- fications of mechanical loaders. Within each classification there are many types and makes available. Table I lists loaders on which manufacturing data as to operating characteristics are available. This paper discusses the conditions met in a mine as they affect these characteristics. It is assumed that management will provide satisfactory engineering, supervision, power, maintenance, loader service within a concentration of workings, and a balanced working cycle served by balanced production equipment. These are factors which affect the optimum operational efficiency of a loader. The conditions which determine loader choice are: Height of Vein—The main limitation to the use of a loading machine is the height to which the vein is mined; i.e. a loader cannot be higher than the place in which it is to work unless rock is taken. Since there are several low vein loaders being developed and successfully applied, this does not appear to be a requisite of an efficient mining operation. The maximum useable height of a loader should be equal to the working seam thickness less a working clearance for travel and operation. A—Working seam thickness = B—Artificial roof support thickness = C—Safe headroom below support = (generally about 6 in.) D—Height of roadway = E—Total of B + C f D =_______________________ A—E = maximum loader height F—Distance from top of roadway to bottom of roof support = G—-Height of loader's coal or ore line (see Table I) = H—Difference between F and G = Size of largest broken particle + a safety factor of 2 to 3 in. H is a loadability factor and is important because the clearance over the top of the conveyor chain to the roof or roof support must be greater than the largest broken particle or else the particle and/or the conveyor chain may be broken. From this standpoint it might be desirable to use a lower height machine even though it may have a smaller capacity, though this is warranted only when increased lump realization offsets lower man-day and machine pro- duction rates. Ivan Given has stated, "Loading should not be handicapped by securing lump only to grind it in the breaker." Width of Working Place—The width of a working place is the greatest width a place may be safely driven. The working place includes not only the face but the roads the loader must tram when mucking out more than one face. The width is limited by the system of placing props with sufficient room between them for the machine runner (about 2 ft). Maximum width of place in which the loader will operate at maximum efficiency is determined by the type of mounting. With track-mounted loaders, maximum width of place is determined by maximum angular swing of the loading head and proximity of track to the face. The use of double track leads to added expense and operational complexities. Several mines that have used double-track systems have found that a substantial saving is made by the use of machines that load out wider places. Trackless loaders may work in rooms of any maximum width. Minimum width of place in which a loader will operate is determined by width of the loader plus a safe movement area for the operator. Often a barodynamic study of the mine will show that either an increase in room width and/or a change in the system of propping may be made by using roof bolting, full or part-width room timbers, removable aluminum I-beams at the face, etc. Increasing the width of a working place will, in general, increase loader operating efficiency by providing more material per fall and by decreasing the preparation and moving time per ton. A change in the system of propping that would increase the minimum width might permit the use of a higher capacity loader with safer working conditions. Proper face tirnbering is necessary to insure safety from roof falls and because the speed of preparation and loading generally increases since the men work with greater assurance and there is less chance of kicking out posts. Maximum Room Length—With the exception of the scraper and the duckbill, the limit to room

Jan 1, 1952

By C. P. Lawhon, J. P. Simpson, W. M. Evans

Data obtained under controlled test conditions using a microbit drilling machine showed that oil emulsified in water muds may either increase or decrease the drilling rate, depending upon drilling conditions. A low-viscosity oil such as diesel fuel can give drilling rates in limestone almost equal to that of water. Data obtained for water emulsified in oil muds showed little decrease in the drilling rate in water-saturated cores as the water percentage of the mud was increased above the 5- to 10-percent range. Changes in drilling rate were found to be dependent upon the oil or water concentration of the mud and upon the type of formation drilled. Changes in static filtration on paper (API filtrate) did not correlate with filtration while the mud was circulated across rock. INTRODUCTION Oil additions to water muds have been reported to increase drilling rates, provide hole stability and improve filtration control. Eckel' showed that water-base emulsion muds used in the West Texas area increased drilling rate with increasing oil concentration up to 15 percent oil by volume, but drilling rate decreased at a concentration of 20 percent by volume. Based on laboratory tests using water muds to drill shale, Cunningham and Goins' reported that drilling rates increased and tendency for the bit to ballup decreased with the addition of oil. Percentage increase in drilling rate varied with the particular formation. They showed oil additions to improve drilling rates ap proximately 75 percent in Vicksburg shale and as much as 150 percent in Miocene shale. Each investigation showed an optimum oil content for the particular formation. Most data that indicated improved filtration control due to oil additions were based on static API Eltrates through paper rather than dynamic filtration through permeable rocks. Some types of dynamic test give a better representation of filtration down-hole while drilling and might be more likely to show some correlation with drilling rate. Static filtration would be important, of course, in relation to hole stability and formation damage. This laboratory's drilling tests, conducted on water-raturated Berea sandstone, indicated that improvements in drilling rate were not evident with increasing oil concentration in water-base muds. Investigation also showed similarity between oil-emulsion (water-in-oil) muds and water-emulsion (oil-in-water) muds while drilling these formations. In Lueders limestone high concentration of water-in-oil muds and high concentration of oil-in-water muds provided the same relative drilling rates. In Berea sandstone there was a large reduction in relative drilling rate with both the oil and water muds that contained low percentages of emulsified fluid. Dynamic filtration rates of water muds on rock did not always decrease with increasing oil percentages even though the static API filtration rates on paper did decrease. Data observed in laboratory drilling of limestone and sandstone indicate that improvements in field drilling operations when water- or oil-emulsion muds are wed may not be the result of increased drilling rates but of improved hole conditions. In some cases, actual drilling rates might be slower but improved hole conditions will result in less total time on the hole. DEFINITIONS Mud pressure—Pressure of drilling fluid as measured after leaving the drilling chamber. This is considered as the approximate mud pressure just past the bit and at the face of the formation. Terrastatic pressure—Pressure representing weight of overburden. Formation pressure—Pressure of formation fluid as measured at outlet of drilling chamber. This is considered as approximate pressure of fluid in the pores of the formation. Differential pressure—Difference between the mud pressure and formation pressure. Relative drilling rate, percent—Drilling rate with experimental fluid divided by drilling rate with water times 100 equals percent. LABORATORY EQUiPMENT AND TESTING PROCEDURES The drilling equipment has been described in previous publications The microbit drill is a closed system (capacity, approximately 7 gal) that can be pressurized to 15.000 psi and heated to 500F. Main components are a drilling chamber, filter-heater, rotary-drive and variable-speed cir-

By M. Bevis, E. O. Fearon, P. C. Rowlands

Fe-Ni and Fe-Ni-C martensite specimens have been deformed in compression at room temperature and the habit planes of operative deformation twins determined by two-surface optical trace analysis. The full orientations of the martensite crystals were determined from divergent X-ray beam diffraction patterns. The experimental results are in excelled agreement with predicted twinning modes. In particular, the habit planes of some deformation twins in bcc martensites are consistent with a "Type XI compound'' twinning mode with Kl, Kz, 71, 77~ elements given by {5, 8, 11) {ioi}, (33) (ill) Tetragonal derivatives of this mode are operative in bct martensites. UnUSUAL deformation twinning modes have been reported by Richman' to occur in Fe-Ni-C martensites with bcc and bct structures. The twin habit planes were determined by single-surface trace analysis (pole locus method) and the remaining twinning elements were determined from the geometry of twin-twin intersections. The indices assigned to the observed habit planes are (3 101, "(089)" and "{0, 1,13)" or "{1,2,7} ", and only in the first case do the twinning elements correspond to a predicted twinning mode. This is mode 1.4 in the paper by Bevis et al. The results presented in Ref. 2 indicate that previously unpublished bcc and bct modes should be operative in preference to the (130) mode and anomalous modes reported by Richman. In view of these results and the uncertainties involved in determining habit planes from single-surface trace analysis and twinning elements from twin-twin intersections5 a two-surface trace analysis of deformation twins in Fe-Ni and Fe-Ni-C martensites has been carried out. EXPERIMENTAL PROCEDURES Two alloys with compositions Fe-23 pct Ni-0.6 pct C and Fe-30.4 pct Ni were prepared from 4N pure materials by induction melting under a vacuum of 10"5 mm Hg. The alloys were homogenized at 1350'~ for 5 days. Both of these alloys are austenitic at room temperature with M, temperature - — 50"C. The aus-tenite grain size of the Fe-Ni-C alloy was approximately 300 to 400 p. The Fe-Ni alloy was remelted in a vertical tube furnace and the melt lowered slowly from the hot zone of the furnace to produce s ingle -crystal austenite specimens. Specimens approximately 10 by 5 by 5 mm were cut from the ingots and quenched to various temperatures below the Ms temperature. The specimens were elec-tropolished in a 10 pct perchloric acetic electrolyte before being deformed in compression at room temperature. Martensite plates which exhibited profuse deformation twinning were selected for analysis and the specimen polished on a second surface such that the two surfaces which contained the martensite plate enclosed an obtuse angle of approximately 145 deg. The specimens were then electropolished to reveal the traces of the deformation twins on both surfaces. The full orientations of the martensite crystals were determined using a divergent X-ray beam technique (Kossel line technique) employing an AEI SEM2 electron probe microanalyzer. Details of this technique which include a detailed description of the Kossel camera attachment to the microanalyzer used in the present experiments have been discussed elsewhere.3 Only additional details relevant to this investigation are discussed here. The specimens were mounted with one surface normal to the incident electron beam as illustrated schematically in Fig. 1. The martensite plates to be analyzed were located using the normal scanning equipment of the microanalyzer. The position of the electron beam and hence the position of the source of divergent X-rays generated within the crystal could be located to within 1 p. Exposure times of approximately 8 to 10 min were required for back-reflection Kossel patterns and it was found that useful diffraction patterns could be obtained consistently from heavily deformed martensite plates. A reference line (carbon contamination mark) produced on the two surfaces of the specimen by scanning the electron beam in a direction having a known relationship with the reference !ine in the X-ray camera enabled the full orientation of the crystals to be determined. Martensite plates with widths as small as 8 p could be oriented using this procedure. The Kossel line patterns were interpreted using the charts developed by Rowlands and ~evis~ as generally

Jan 1, 1969

By R. Stickler, A. Vinckier

An optical and electron microscope study was made on a commercial 302 stainless steel heat treated for massive carbide precipitation. Convincirg evidence was obtained that the grain boundary precipitate does not grow away from the grain boundary into the matrix, but grows as a network of large thin dendrites in between the grains. IN austenitic stainless steels the carbon in supersaturated solution precipitates when the steel is heated in the temperature range 450" to 1000°C. During such heat treatments the chromium-rich carbide occurs primarily at the grain boundaries and has adverse effects on the corrosion resistance and low-temperature ductility of the material. It has been shown that the morphology of the precipitated particles differs widely depending on the time and temperature of the heat treatment, the nature of the boundary, the misfit between the grains, and so forth.1"5 It was assumed by Mahla et al.,' Streicher,' and Mc Nutt' that the carbide particles which nucleate in the grain boundary grow in various geometric or dendritic forms away from the boundary into the matrix. However, Kinzel,' Hatwell et a, and Plateau et aL4 found that the particles nucleate in the grain boundary and grow as a network of thin dendrites in the grain boundary interface. We have made a comprehensive studyg of the precipitation occurring in a commercial 302 austenitic stainless steel heat treated for times ranging from 0.15 to 1500 hr at various temperatures from 480" to 1065"~. This study was made to elucidate the influence of heat treatments on both the mechanical and the corrosion properties of this steel. Part of this investigation which is pertinent to the morphology of the grain boundary carbides referred to above is separately reported here. We found that the particles which nucleated in the boundaries grew in the interface of these boundaries, thus supporting the viewpoints of Kinzel,' Hatwell et al.,3 and Plateau et al.4 Furthermore, when carbide particles nucleated in the matrix very close to the boundaries, they possessed a morphology distinctively different from the particles growing in the grain boundaries. MATERIAL A study of metallographic samples and of fracture surfaces of a 302 stainless steel is reported in this paper. The composition and heat treatments are listed in Table I. Polished and etched samples were examined und813r the optical microscope, and carbon extraction replicas of etched micrographic samples and various fracture surfaces3'8'9 were examined under the electron microscope. RESULTS AND DISCUSSION A representative optical micrograph of the 302 steel, condition A, is shown in Fig. l(a). Particles can be seen on the grain boundaries but no traces can be found of particles which grow from the grain boundaries into the matrix. A carbon extraction replica of this sample shows numerous large thin dendrites, Fig. l(b). The lateral dimension of such carbide particles vary up to 100 p, and their thickness estimated from the amoun! of electron penetration i:; between 500 and 1000A. Such large dendrites are extracted from almost all grain boundaries and, if they had grown into the grains, they would definitely be revealed by etching traces in the matrix, Fig. l(a). The reason why these large dendrites on the extraction replica appear to be grown into the grain is due to the mechanism of the extraction replica process. Thus, these dendrites are supported by the carbon replica film only at the edges originally along the grain boundary trace A-A, Fig. l(b), in the polished metal section and have subsequently fallen over onto the carbon replica film during handling. Although such dendrites generally fall only to one particular side of the grain boundary trace, one finds occasionally that parts of a dendrite have fallen to both sides, as shown in Fig. l(b). Further evidence for the growth of carbide in the grain boundary can be obtained from the appearance of fracture surfaces. A small impact specimen of the 302 steel, condition A, was broken at liquid nitrogen temperature. The fracture path follows the

Jan 1, 1962

By David S. Bolin

INTRODUCTION This paper is directed toward those companies or individuals who may be considering the possibility of tin exploration or development projects in South America. Although tin deposits are known in many countries of Latin-America including Argentina, Peru, and Mexico, the majority of the deposits are located in Bolivia and Brazil. These two countries also account for virtually all the current production. Many factors affect the economic decisions related to mining and exploration projects in this region including the following: 1) Types of deposits 2) Anticipated size and grade of deposits 3) Deposit geometry and ore distribution as it affects the selection of a mining method 4) Metallurgical amenability 5) Governmental policies 6) Taxation 7) Anticipated capital and operating costs 8) Marketing costs This discussion will be directed toward each of these points. The majority of the presentation will be concentrated on Bolivia as this country is the principal producer in the region, however, the potential for further tin development in Brazil is excellent. Due to the remote and previously almost inaccessible location of the stanniferous districts of Brazil, little is known with respect to size and type of non-alluvial deposits which may exist in this vast country. TYPES OF DEPOSITS Two major types of deposits are currently being exploited in Bolivia; alluvial, and hard rock or lode deposits. Bolivia produces substantial tin from both types of deposit whereas virtually all Brazilian production to date has been from alluvial sources. Alluvial Deposits Brazil: The alluvial tin deposits of Brazil are located in river channels and flood plains adjacent to low mountain ranges. The terrain containing the tin placers is flat, marshy, and generally jungle covered. The major controls of alluvial cassiterite concentration are the ancient and present stream channels. The average tin concentration in the placers varies from 500 grams to approximately 1.0 kilograms per cubic meter. Tin reserves in the Rondonia field of Brazil have been estimated at 600,000 tons of fine tin. A bucketwheel suction dredge went into production in the Rondonia district in 1979, and four others have since been ordered. Several other gravel pump, and hand mining operations are also in production in this field. In addition to the Rondonia district, tin occurrences are known from Xingu, in Para state, and in the state of Minas Gerais. Bolivia: The alluvial deposits of Bolivia are somewhat more complex due to the variable geomorphology and abrupt topography. Conventional placer accumulations of cassiterite are found in many stream channels and intermontane basins surrounding the major lode tin producing regions. In addition to stream and valley placers, a group of deposits locally referred to as "Pallacos" or "Llamperas" which consist of colluvium, landslide debris and glacial moraine material, contain substantial tin reserves in some areas. The stream channel and intermontane basins contain the only deposits which are presently being exploited by mechanized methods. One dredge is working the stream channel below Cerro Rico de Potosi and another is operating in an intermontane basin southeast of the city of Oruro. Both of these dredges are operated by private companies. The average grade for these operations varies from 250 to 500 grams per cubic meter. The largest of the intermontane basin placers known at present is the Centenario deposit located adjacent to the Catavi lode deposit. This deposit contains approximately 170 million cubic meters of material with an average grade of about 150 grams per cubic meter. The "Pallacos" deposits are found on the slopes of mineralized areas and in glacial moraine. The mineralized material is generally completely unsorted, with tin and sometimes tungsten values distributed erratically throughout the entire mass. Most of these deposits are worked by small leasors or cooperatives; however, at least one mechanized washing plant is in operation southeast of Oruro. The size of these deposits may reach up to several million cubic yards. Grades are very erratic, but may range from 200 to 500 grams per cubic yard. In addition to the formal mining operations, virtually every drainage surrounding the major mines is being worked by independent' miners utilizing hand mining and jig or pan concentration. The aggregate production from these operations is substantial. The

Jan 1, 1982

By John C. Calhoun, R. C. Newman

A report is made of experimental work performed on the capillary retention of water within porous solid systems, the displacement being accomplished with air and various organic liquids. A portion of the experiments were designed to measure the lowering of vapor pressure of water within a porous solid with subsequent conversion of such vapor pressure data to capillary pressure values. The form of the capillary pressure curve at high capillary pressures has been elucidated from this data. Certain theoretical approaches are presented to indicate the correlation between work done by previous investigators. The present work is correlated also with theory. Surface area values are calculated for the various core systems studied. INTRODUCTION Leverettl in 1941 presented a paper which gave the essential concepts of capillary behavior in porous solids. His presentation included both theoretical and experimental aspects of the problem. He defined the term "capillary pressure" and applied it to an ideal porous system. His work included the definition of a dimensionless quantity which was a function of fluid saturation and which could be correlated with porosity and permeability for clean, unconsolidated sands. His experimental work was performed by the drainage of water from packed columns of unconsolidated sands. Subsequently, other authors have presented experimental techniques which permit the determination of capillary pressure data on small core samples. Data have been presented on porous systems other than unconsolidated sand and with the use of liquids other than water. Notable among these are the works of Hassler, Brunner and Deahl,2 Bruce and Welge,³ Amyx and Yuster, and Purcell. Others have indicated the applicability of such data to field problems without regard to the theoretical aspects of the capillary pressure saturation function. Within the recent published literature there have also been reported studies of the correlations between capillary pressure data and other fundamental properties of porous solids. It was the intent of the present reported work to investigate the behavior noted by water and various other liquids within porous systems in an attempt to amplify existing correlations between capillary properties, surface properties, and other fundamental characteristics of porous systems. The experimental work described here was performed as two different investigations but due to its nature it is reported as separate phases of the same general topic. CAPILLARY PRESSURE AND VAPOR PRESSURE LOWERING It has long been recognized that the vapor pressure above the curved surface of a liquid is a function of the curvature of the liquid surface." The capillary pressure is also a function of the curvature of the liquid surface. Both capillary pressure values and vapor pressure lowering are, therefore, functions of the liquid saturation of a porous solid. A quantitative relationship between the vapor pressure lowering and the capillary pressure can be simply developed by considering a porous solid system containing water in equilibrium with its vapor. The capillary pressure at any height within the system is defined as Pc= Pv -P1.......(1) where PI is the pressure in the vapor phase and PI is the pressure in the liquid phase. Consider that both the water and its vapor are continuous phases within the system and that at any point the two phases are in equilibrium. The gradients in the liquid and vapor columns within the porous system are: PI = plgdh dPv = pvgdh By integrating these gradients from the point where h = 0 to the height h, values of PI and PI at the point h are found. Let the point where h = 0 be that where Pc = 0. At this point also Pv is equal to Pve, the equilibrium vapor pressure of the liquid above a flat surface. From the first of these integrations since p is independent of height: P = p1gh + P, From the second, by substituting pv = PvM/RT, where M is the molecular RT weight: Pv M Pvo- RT gh By combining the two last equations to eliminate h, one obtains: P1 RT Pv Substituting, values for Pv and Pi in equation (1) gives PyRT RT Pv which is approximately Pc=RT/Mp1 In Pvo/Pv .......(2) This equation relates the vapor pressure above a curved surface with the capillary pressure across the curved surface in terms of measurable quantities. The equivalent of this equation is given by Freundlich."

Jan 1, 1949

By V. F. Hollister

The Queen Charlotte gold deposit (also known as the Specogna, Babe, or Cinola) was discovered in late 1970 by Efrem Specogna and Johnny Trico. They were prospecting along the trace of the Sandspit fault, and they sampled jarositic material that included veins from the fault zone. Their assays included some good gold values. They located the Babe Claims in 1971 and optioned them to Kennco Explorations Ltd. Kennco conducted stream sediment and soil geochem studies, geological mapping and drilling of 55.2 m (181 ft) in two drill holes. Kennco withdrew from the property, and by 1977, Cominco, Placer Development, Silver Standard, and Quintana Minerals had each successively worked on the deposit. Consolidated Cinola Mines bought the claims in 1977 and completed exploration of the deposit ultimately in a joint venture arrangement with Energy Reserves. Energy Reserves entered in late 1979, and by 1983, a total of 200 surface and 12 underground drill holes had been completed, totaling 28 600 m (93,832 ft). In addition, a 461.9 m (1515 ft) adit was driven in the ore body. Reserves published by Cinola aggregate 34 Mt (37 million st) of 1.7 g (0.060 oz) Au per tonne. All industry geologists working in the area agree that the Queen Charlotte gold is an epithermal gold deposit in porous volcaniclastic and clastic rocks that is genetically related to a Miocene-Pliocene rhyolite plug. The geologic description here follows the oral presentation made by G. G. Richards, J. S. Christie, and M. R. Wolfhard at a 1976 CIM meeting. Additional comments by the late C. S. Ney of Kennco Explorations are included with the Richards, Christie, and Wolfhard data to complete the geologic set- ting. The attached reprint by Champigny and Sinclair (1 980) provides additional data on the deposit. The Queen Charlotte (Babe, Specogna, or Cinola) gold deposit is located on Graham Island in the northern Charlotte Islands, at the fault boundary of the Skidegate plateau and the Charlotte lowlands. The Sandspit fault marks the physiographic boundary, and it is intruded by rhyolite porphyry at the deposit. Because displaced geochem anomalies, drain- age patterns, and topography suggest dextral and east side down movement for the fault, exposed east block rocks are younger than rocks west of the fault. The east block, which included the ore deposit, is a lowland largely masked by unconsolidated Pleistocene and Recent clastic rocks. Rocks west of the rhyolite plug, on the Skidegate plateau, are Cretaceous carbonaceous and calcareous shale unconformably overlain by a thin veneer of rhyolite tuff. The deposit is about 100 m (328 ft) above sea level. GEOLOGIC SETTING At the ore deposit, the Sandspit fault is a complex structure. However, lithologies on either side of the fault-controlled rhyolite porphyry plug are distinct. West of the rhyolite, the upper member of the Cretaceous Haida formation shale is the most common rock type. The member is composed of dark grey to black, poorly consolidated, and thinly bedded carbonaceous and calcareous shale. The sequence is silicified to an argillite or a hornfels near the rhyolite. West of the rhyolite porphyry plug, but not importantly involved in the mineralization, is a thin masking cover of rhyolite tuff. The tuff unconformably succeeds the cretaceous shale, but it is largely eroded in the mine area. East of the fault-controlled rhyolite porphyry plug is a thick section of conglomerate and sandstone of the Miocene- Pliocene Skonun formation. The ore body occurs within the coarse clastics, the rhyolite intrusive as the western boundary. Ore is entirely contained within the clastics. Original permeability of the clastic rocks was a major control for ore deposition and alteration, and for that reason, the Skonun formation is described in greater detail. The Skonun formation clastics unconformably overlie Haida shale. The Skonun is at least 300 m (984 ft) thick in the mine area, where it trends northerly and dips easterly 15º to 25º. The sequence is about 62 percent conglomerate, 3 1 percent coarse arkosic sandstone, and 7 percent interbedded siltstone and sandstone. Contacts between adjacent beds are generally sharp. Stratigraphic correlations between drill

Jan 1, 1985

By John C. Calhoun, R. C. Newman

A report is made of experimental work performed on the capillary retention of water within porous solid systems, the displacement being accomplished with air and various organic liquids. A portion of the experiments were designed to measure the lowering of vapor pressure of water within a porous solid with subsequent conversion of such vapor pressure data to capillary pressure values. The form of the capillary pressure curve at high capillary pressures has been elucidated from this data. Certain theoretical approaches are presented to indicate the correlation between work done by previous investigators. The present work is correlated also with theory. Surface area values are calculated for the various core systems studied. INTRODUCTION Leverettl in 1941 presented a paper which gave the essential concepts of capillary behavior in porous solids. His presentation included both theoretical and experimental aspects of the problem. He defined the term "capillary pressure" and applied it to an ideal porous system. His work included the definition of a dimensionless quantity which was a function of fluid saturation and which could be correlated with porosity and permeability for clean, unconsolidated sands. His experimental work was performed by the drainage of water from packed columns of unconsolidated sands. Subsequently, other authors have presented experimental techniques which permit the determination of capillary pressure data on small core samples. Data have been presented on porous systems other than unconsolidated sand and with the use of liquids other than water. Notable among these are the works of Hassler, Brunner and Deahl,2 Bruce and Welge,³ Amyx and Yuster, and Purcell. Others have indicated the applicability of such data to field problems without regard to the theoretical aspects of the capillary pressure saturation function. Within the recent published literature there have also been reported studies of the correlations between capillary pressure data and other fundamental properties of porous solids. It was the intent of the present reported work to investigate the behavior noted by water and various other liquids within porous systems in an attempt to amplify existing correlations between capillary properties, surface properties, and other fundamental characteristics of porous systems. The experimental work described here was performed as two different investigations but due to its nature it is reported as separate phases of the same general topic. CAPILLARY PRESSURE AND VAPOR PRESSURE LOWERING It has long been recognized that the vapor pressure above the curved surface of a liquid is a function of the curvature of the liquid surface." The capillary pressure is also a function of the curvature of the liquid surface. Both capillary pressure values and vapor pressure lowering are, therefore, functions of the liquid saturation of a porous solid. A quantitative relationship between the vapor pressure lowering and the capillary pressure can be simply developed by considering a porous solid system containing water in equilibrium with its vapor. The capillary pressure at any height within the system is defined as Pc= Pv -P1.......(1) where PI is the pressure in the vapor phase and PI is the pressure in the liquid phase. Consider that both the water and its vapor are continuous phases within the system and that at any point the two phases are in equilibrium. The gradients in the liquid and vapor columns within the porous system are: PI = plgdh dPv = pvgdh By integrating these gradients from the point where h = 0 to the height h, values of PI and PI at the point h are found. Let the point where h = 0 be that where Pc = 0. At this point also Pv is equal to Pve, the equilibrium vapor pressure of the liquid above a flat surface. From the first of these integrations since p is independent of height: P = p1gh + P, From the second, by substituting pv = PvM/RT, where M is the molecular RT weight: Pv M Pvo- RT gh By combining the two last equations to eliminate h, one obtains: P1 RT Pv Substituting, values for Pv and Pi in equation (1) gives PyRT RT Pv which is approximately Pc=RT/Mp1 In Pvo/Pv .......(2) This equation relates the vapor pressure above a curved surface with the capillary pressure across the curved surface in terms of measurable quantities. The equivalent of this equation is given by Freundlich."

Jan 1, 1949

By J. E. Andersen, J. Halpern, C. S. Samis

In the presence of oxygen, galena is oxidized in an aqueous medium containing sodium hydroxide, in accordance with the following reaction: PbS + 2O2 + 3OH ? HPbO2 + SO4 = + H2O A novel method was devised for following this reaction which takes place in an autoclave under oxygen pressure, by measuring the concentration of HPbO2- in the solution with a cathode ray polarograph employing stationary platinum electrodes. Using this procedure a study was made of the kinetics of the reaction, in which the effect of a number of variables, including temperature, oxygen pressure, NaOH concentration, and agitation, on the rate, were determined. The results of this study are described and discussed, in terms of possible mechanisms for the reaction. IT is known that sulphide minerals can be oxidized in aqueous media in the presence of oxygen under pressure. Reactions of this type can be classified in two categories depending upon whether the products of oxidation are insoluble or soluble in the aqueous medium. An example of the first type of reaction is the oxidation of pyrite in alkaline solutions, giving rise to an insoluble iron oxide. The kinetics of this reaction have been investigated and its mechanism established.' It has been applied in the oxidation of iron sulphides present in refractory gold ores to improve the subsequent recovery of gold by cyanida-tion.' The second type of reaction finds application where it is desired to recover the metal by leaching during oxidation. In this case a medium is selected in which the oxidized mineral is soluble. For example, nickel, copper, and cobalt sulphide ores can be treated by oxidation in the presence of a solution of ammonia dissolving the nickel, copper, and cobalt as the metal ammine sulphate salts.:' A similar treatment has also been reported to apply to zinc sulphide ores.' It is known that lead sulphate is soluble in solutions of sodium hydroxide or ammonium acetate. It should therefore be possible to dissolve the lead from galena ores by aqueous oxidation with oxygen under pressure using either of these solutions. The applicability of the ammonium acetate treatment has been investigated and confirmed in a recent study.' The present paper describes the results of a similar study in which the kinetics of the oxidation of galena in sodium hydroxide solutions have been investigated. The object of this investigation was pri- marily to obtain information of a fundamental nature relating to the kinetics and mechanism of this reaction. The use of pulps of comminuted ore in a study of this type is undesirable because of the difficulty in controlling and measuring the surface area. The measurements were therefore made using galena crystals of measured surface area and in this way absolute reaction rates were obtained. The reaction was found to proceed as follows: PbS + 2O2 + 3OH ? HPbO2 + SO4 + H2O [I] The products are sodium plumbite and sodium sulphate salts which dissolve in the aqueous solution. The reaction studies were carried out in an autoclave in which a desired pressure of oxygen was maintained. The reaction was followed by measuring the concentration of lead in the solution with a cathode ray polarograph. The results obtained in this investigation are presented and discussed in the present paper. Experimental Materials: The crystals of galena were obtained from Violamac Mines, Sandon, B. C. The following impurities were indicated by spectrographic analysis carried out by the Provincial Assay Office, Victoria, B. C.: Sn, 0.02 to 0.2 pct; Sb, 0.07 to 0.7; Zn, 0.01 to 0.1; Si, Fe, Mg, As, less than 0.05 pct; Ag, 126 oz per ton, the latter determined by standard fire-assaying procedure. After cutting a specimen measuring approximately 5x7x12 mm, the crystal surfaces were ground parallel to the 100 axes using No. 2 emery, washed with water, and the dimensions were measured with a micrometer. Oxygen gas was of commercial grade and supplied in cylinders by Canadian Liquid Air. Solutions were made up with chemicals of chemically pure grade and distilled water. Equipment: Autoclave: The autoclave used in these studies was constructed of stainless steel and

Jan 1, 1954

By J. N. Breston, R. V. Hughes

Conclusions drawn by previous research workers with reSPect to the relation between Pressure gradients and/or velocity and oil recovery obtained by laboratory water flood tests have been in disagreement probably due to variable procedures and unnatural conditions and materials. The Bradford Laboratory of the Pennsylvania Grade Crude Oil Association as part of its secondary recovery research program has conducted nineteen water floods on two long cores of widely differing characteristics in an attempt to clarify this relationship and make it an aid in predicting flooding pressures in the field. Unlike previous research procedures the present experiments were conducted with the aim of duplicating field conditions as closely as possible by using long unextracted consolidated cores, a live crude, and natural brines for both flooding and, connate water content. Also, the pressure gradients and flooding velocities were representative of field conditions where similar sands were being flooded. Eleven floods on one core and eight floods on the other core showed increased recoveries and lower residual oil saturation with increased flood pressure gradients and flood velocities. A marked decrease in recovery was obtained from both cores at very low flood velocities. This pressure versus recovery relationship is shown to hold up to the point of water breakthrough and also up to the 100 and 1 produced water to oil ratio point. INTRODUCTION The possibility of water flooding oil sands was suggested by Carl1 of the Pennsylvania Geological Survey in 1880. It is not known when the practice was tried intentionally for the first time, but its beneficial effects were noted in the annual production rate of the Bradford field as early as 1907. The practice was illegal in Pennsylvania until 1921. Early water floods in the Bradford field usually consisted of shooting or splitting the casing secretly to permit subsurface waters to enter the producing sands under hydrostatic head. As it was noted that the benefits of water flooding seemed to be proportional to the quantity of water dumped into the well many also began to utilize surface sources after the practice became legal. It was probably during the middle 20's before many producers realized that the pressurehead of the water upon the producing sand determined the rate and quantity of water that would enter the sand. Hence, rate and quantity of production appeared to be a direct function of input pressures. By 1927 a few producers had ventured the installation of pressure pumps in order to increase water-input rates and production through the combination of hydrostatic and hydraulic pressures. The adoption of pressure flooding and the "five-spot" drilling pattern in the Bradford field were essentially simultaneous. Water-input pressures in 1930 seldom exceeded 300 p.s.i. at the well head or 1100 p.s.i. at the sand face. Since that time, water-flood producers in the Bradford-Allegany fields have gone to higher and higher pressure until today 600 p.s.i. at the well heads is called a low pressure flood. Many high pressure floods now operate at 1300-1400 p.s.i. at the well head. The limiting and advisable pressure at the sand face has been pronounced as that pressure just under what is required to lift the overburden or to cause formation parting: According to this rule any water flood operation utilizing well-head pressures nearly equal in pounds per sq. in. to 1.1 times the average depth in feet to the top of the producing sand would be considered as a high-pressure flood. Despite the higher pressure trends in the Bradford-Allegany field operations and the results of early laboratory water flooding research, the desirability and benefits of high input pressures are still questioned by many operators, particularly in midwestern water flood operations. The present paper recounts a series of 19 laboratory water floods using two long, consolidated cores of widely differing characteristics saturated with live crude and flooded with oil field brines in an effort to simulate field conditions under • various pressure gradients and flooding velocities. For both cores, higher recoveries and lower residual oil saturations were obtained at higher pressure gradients and flood velocities. This relationship is shown to hold up to the water breakthrough point and also up to the 100 to 1 produced water to oil ratio point.

Jan 1, 1949

By W. Rostoker

Single isothermal sections were constructed for the titonium-rich corners of the systems Ti-Fe-O, Ti-Cr-O, and Ti-Ni-0 with a view to locating the shape and disposition of the ternary intermediate-phase fields for the compounds isomorphous with Fe3W3C. IN a previous note,' it was reported that a group of ternary intermediate phases existed which occurred in the general composition range Ti,X,O-Ti&O where X was one of the following elements: copper, nickel, cobalt, iron, or manganese. In two instances, binary intermediate phases occurred (Ti²Cu and Ti²Ni) which appeared to be isomorphous. The X-ray diffraction patterns of the phases could be indexed on a cubic lattice whose cell edge was of the order of 11 kX. Karlsson2 stated that the line extinctions and line intensities indicated that these phases were isomorphous with Fe³W³C and therefore belonged to the space group Oh. This author also noted that no unique phase of this type occurred at the composition Ti,Cr,O. This latter statement was accepted as true at the time the previous technical note was written.' However, work continued along these lines and that reported here has shown that a phase isomorphous with Fe³W³C does exist in the vicinity of the composition Ti³Cr³O but not at or near Ti4 Cr²O. The lattice parameter of this phase was found to be 13.01 kX. Metallographic examination of both as-cast and annealed specimens of these supposed ternary oxide phases disclosed structures which were far from single phase in many instances. It was considered a point of some interest to locate more positively the composition coordinates of the single-phase fields. To this end, single isothermal sections for the systems Ti-Fe-O (1000°C), Ti-Cr-0 (1000°C), and Ti-Ni-0 (900"C) were constructed. Phase relationships were studied by both X-ray diffraction and metallotrra~hic methods. Allovs were prepared as 10 g buttons by melting in a noncon-sumable electrode, water-cooled copper crucible arc-melting furnace using a helium atmosphere. Oxygen was introduced quantitatively by the use of weighed amounts of TiO² or TiO. Iodide titanium and the purest available alloying metals were used. All results are discussed in terms of the nominal composition of the melts. Previous experience with making oxygen-rich alloys had shown that oxygen losses were not significant if a homogeneous melt was produced. Weight-loss measurements were used to check loss in metallics during melting. Anneals were conducted in evacuated Vycor bulbs, and annealing times ranged from 24 hr at 1000 °C to 48 hr at 900°C. To achieve equilibrium in certain sluggish alloys, seven-day anneals were used. Debye-Scherrer powder patterns were taken in a 14 cm diam camera using filtered CuK radiation (K² = 1.541232 kX; K., = 1.53739 kX). Specimens were prepared by crushing and screening previously annealed buttons. In general, the X-ray diffraction results were used to identify the major phases, while the metallographic examinations were more useful in indicating the number of phases present. By the use of the combined results and general fundamental rules governing ternary equilibrium, it was possible to construct isothermal sections in good detail. In some instances where auxiliary lattice-parameter data were available, it was possible to lay down tie lines and to locate more positively corners of three-phase fields. Isothermal Section of the System Ti-Fe-O at 1000°C The binary systems Ti-O³ and Ti-Fe4 have been published. Binary phases, TiO, TiFe, and TiFe2, are likely to be encountered in the titanium-rich corner of the system. The structures are NaCl (Bl), CsCl (B2), and MgZn, (C14) types, respectively. Although preliminary X-ray diffraction studies indicated the presence of a ternary phase in the composition range Ti,Fe,O-TiJ?e,O, metallographic examination of two specimens at these compositions revealed the presence of other phases. Thirty-eight alloys were used to delineate the phase boundaries of the isothermal section illustrated in Fig. 1. The five almost single-phase ter-

Jan 1, 1956

By N. J. Grant, R. Nordheim

An extensive study was made of the aging characteristics of alloys based on the 80 pct Ni-20 pct Cr composition hardened with aluminum and/or titanium, each up to 4 pct. Aging was followed by means of hardness and hot electrical resistance measurements as well as by X-ray and microscopy. Stress rupture tests at 1500°F were utilized as a check on the predicted behavior. THE titanium and aluminum hardened Ni-Cr alloys, exemplified by Nimonic 80 and Inconel X, constitute one of the more important groups of alloys developed to meet the demand for materials retaining their strength at elevated temperatures. For service in the temperature range 1200" to 1500°F, these alloys offer high creep resistance. With increasing service temperature, however, the strength of the simpler Ni-Cr base alloys falls off rapidly so that above 1500°F there is a significant loss of strength. The present investigation was undertaken with the hope that a better understanding of the factors controlling the precipitation hardening of these alloys would make it possible to increase the useful service temperature range. Primarily this investigation involved the study of the effects of titanium and aluminum on the hardening and the subsequent softening at elevated temperatures. The titanium and aluminum contents were each varied between 0 and 4 pct by weight at a constant nickel to chromium weight ratio of about 4:1. (Except when otherwise stated, all compositions are expressed on a weight basis.) The major part of the investigation was confined to alloys with less than 0.06 pct C. Recently several papers dealing with the identity of the microconstituents in the titanium and aluminum hardened Ni-Cr alloys have been published. Using X-ray analysis of the residues from anodic dissolution, Rosenbauml was only able to identify carbides and nitrides in Nimonic 80 and Inconel X. However, since Rosenbaum worked with alloys in the hot rolled rather than in the aged condition, his results are inconclusive. Recently Hignett' reported that the hardening of Nimonic 80 was due to the controlled precipitation of Ni,(TiAl) having the cubic Ni3A1 structure. Taylor and Floydv-" published the results of an investigation of the nickel-rich corner of the Ni-Cr-Ti, Ni-Cr-Al, and Ni-Ti-A1 systems. In the Ni-Ti and the Ni-A1 systems the hexagonal Ni,Ti phase, 7, and the cubic Ni3A1 phase, -y', respectively, exist in equilibrium with the nickel-rich solid solution. The interatomic distances in the basal plane of Ni,Ti and the octahedral planes of the matrix are almost equal, thus explaining the Wid-manstaetten type structure formed when Ni,Ti precipitates from solid solution. When Ni:,Al precipitates from solid solution, it appears usually in globular form, often dispersed along rows corresponding to definite crystallographic directions. The 7 and phases are also the only intermetallic compounds which occur in the nickel ternary alloys with up to 25 pct Cr and 10 pct Ti or Al. Taylor and Floyd found that Ni,Ti takes practically no nickel, chromium, or aluminum into solution. Nial, on the other hand, dissolves a considerable amount of chromium and titanium and some nickel. Up to three out of every five aluminum atoms could be replaced by titanium in Ni,Al. This substitution caused a slight increase (less than 1 pct) in the lattice parameter. With respect to the effect of variation in the titanium and aluminum contents on the high temperature strength of Nimonic 80 type alloys, Pfeil, Allen, and Conway" reported that an 80 pct Ni-20 pct Cr alloy containing 0.20 to 0.30 pct A1 had the highest creep resistance when the titanium content was kept between 1.65 and 2.75 pct. Experimental Procedure The materials used for this investigation were electrolytic nickel, electrolytic or low carbon chromium, sponge titanium and 2s aluminum. The alloys were melted in an indirect carbon arc furnace under

Jan 1, 1955

By R. V. Hughes, J. N. Breston

Conclusions drawn by previous research workers with reSPect to the relation between Pressure gradients and/or velocity and oil recovery obtained by laboratory water flood tests have been in disagreement probably due to variable procedures and unnatural conditions and materials. The Bradford Laboratory of the Pennsylvania Grade Crude Oil Association as part of its secondary recovery research program has conducted nineteen water floods on two long cores of widely differing characteristics in an attempt to clarify this relationship and make it an aid in predicting flooding pressures in the field. Unlike previous research procedures the present experiments were conducted with the aim of duplicating field conditions as closely as possible by using long unextracted consolidated cores, a live crude, and natural brines for both flooding and, connate water content. Also, the pressure gradients and flooding velocities were representative of field conditions where similar sands were being flooded. Eleven floods on one core and eight floods on the other core showed increased recoveries and lower residual oil saturation with increased flood pressure gradients and flood velocities. A marked decrease in recovery was obtained from both cores at very low flood velocities. This pressure versus recovery relationship is shown to hold up to the point of water breakthrough and also up to the 100 and 1 produced water to oil ratio point. INTRODUCTION The possibility of water flooding oil sands was suggested by Carl1 of the Pennsylvania Geological Survey in 1880. It is not known when the practice was tried intentionally for the first time, but its beneficial effects were noted in the annual production rate of the Bradford field as early as 1907. The practice was illegal in Pennsylvania until 1921. Early water floods in the Bradford field usually consisted of shooting or splitting the casing secretly to permit subsurface waters to enter the producing sands under hydrostatic head. As it was noted that the benefits of water flooding seemed to be proportional to the quantity of water dumped into the well many also began to utilize surface sources after the practice became legal. It was probably during the middle 20's before many producers realized that the pressurehead of the water upon the producing sand determined the rate and quantity of water that would enter the sand. Hence, rate and quantity of production appeared to be a direct function of input pressures. By 1927 a few producers had ventured the installation of pressure pumps in order to increase water-input rates and production through the combination of hydrostatic and hydraulic pressures. The adoption of pressure flooding and the "five-spot" drilling pattern in the Bradford field were essentially simultaneous. Water-input pressures in 1930 seldom exceeded 300 p.s.i. at the well head or 1100 p.s.i. at the sand face. Since that time, water-flood producers in the Bradford-Allegany fields have gone to higher and higher pressure until today 600 p.s.i. at the well heads is called a low pressure flood. Many high pressure floods now operate at 1300-1400 p.s.i. at the well head. The limiting and advisable pressure at the sand face has been pronounced as that pressure just under what is required to lift the overburden or to cause formation parting: According to this rule any water flood operation utilizing well-head pressures nearly equal in pounds per sq. in. to 1.1 times the average depth in feet to the top of the producing sand would be considered as a high-pressure flood. Despite the higher pressure trends in the Bradford-Allegany field operations and the results of early laboratory water flooding research, the desirability and benefits of high input pressures are still questioned by many operators, particularly in midwestern water flood operations. The present paper recounts a series of 19 laboratory water floods using two long, consolidated cores of widely differing characteristics saturated with live crude and flooded with oil field brines in an effort to simulate field conditions under • various pressure gradients and flooding velocities. For both cores, higher recoveries and lower residual oil saturations were obtained at higher pressure gradients and flood velocities. This relationship is shown to hold up to the water breakthrough point and also up to the 100 to 1 produced water to oil ratio point.

Jan 1, 1949

By E. Martinez

Samples of chrysocolla, a hydrated copper silicate, from several sources were submitted to differential thermal analysis (DTA) and thermal gravimetric analysis (TGA). Pure samples of chrysocolla are difficult to obtain, but comparison of the thermograms revealed that certain reactions occurred in all the samples and it is believed that these are due to chrysocolla. Endothermic reactions occurred at 50' to 175°C, 350° to 650°C, and 980° to 1100°C each of which caused a weight loss. The first was due to loss of absorbed water, the second to a dehydroxyla-tion, and the last to conversion of cupric oxide to cuprous oxide. In addition, two exotherms were detected at 685° to 695°C and 935° to 950°C. Infrared spectra of heated samples indicated the exotherms were due to changes in the Si-O bonds leading to the formation of cristobalite. The results suggest that thermoanalysis may be a more sensitive and reliable method for detection and identification of chrysocolla than X-ray diffraction, infrared spectroscopy, or optical techniques. The recovery of copper from oxide ores has been the subject of much research in recent years. One of the principal oxide copper minerals is chrysocolla, a hydrated copper silicate. The information available indicates that it has widely varying properties depending on the origin of the sample. Chrysocolla usually is found associated with cuprite, malachite, azurite, and native copper. Most of these other minerals are recoverable by present day flotation practice, but chrysocolla is lost in the tailings.1,2 Reagent combinations that are successful in laboratory chrysocolla flotation with ore from one source have been found to be ineffective with another. 3 The copper segregation process offers an altemative to beneficiation of oxide copper ores.4'5 The process is of particular interest in processing ores that cannot be treated by conventional hydrometal-lurgical methods because of high acid consumption.6 Fuller understanding of the properties of chryso- colla may prove of value in the search for improvements in both the flotation and segregation processes. Chrysocolla samples from Arizona, Nevada, Chile, Australia, and South Africa were studied by differential thermal analysis (DTA) and thermal gravimetric analysis (TGA). In addition, a sample from Miami, Ariz., was submitted to X-ray diffraction, infrared spectrophotometry, and surface area determination. EQUlPMENT Differential thermal analysis (DTA) detects, amplifies, and records exothermic-endothermic reactions occurring in a sample as its temperature is raised at a constant rate, usually 10°C per minute. A unit made by the Robert L. Stone Co. was used in this study. The tests can be run if desired with a gas streaming through the sample. A thermobalance records weight losses or gains in a sample as its temperature is raised at a uniform rate. The gravimetric analyses (TGA) were run on a Chevenard thermobalance converted electronically for graphic recording. A heating rate of 5°C per minute up to 1100°C was used in these tests. A Perkin Elmer Infrared Spectrophotometer, Model 221, was used with sodium chloride optics obtaining IR spectra in the 2 to 15 region. A pressed pellet technique with potassium bromide was used in preparing the samples. DESCRIPTION OF SAMPLES Chrysocolla is found in the oxidation zones of copper deposits commonly associated with malachite, azurite, and limonite. It is described as varying in composition and in color from bluish green to brown or black. Inclusions of other minerals are usual so chemical analysis of chrysocolla samples may be suspect. However, it is considered by many to be a solid solution of CuO, SiO2 and H2O with a general formula of CuO.SiO2.2H2O or 2CuO.2SiO2. 3H20. Chukhrov7 has described a sample from the Urals as CU3,5(OH)2 (A1Si3) O10.nH2O and stated that chrysocolla is a montmorillonite-type mineral. On the basis of X-ray analyses, DTA, and infrared spectra of chrysocolla from the Inspiration Mine, Ariz., Sun8 concluded that there was no substantial evidence to classify it as a montmorillonite mineral. Chrysocolla samples from many sources throughout the world were used in this investigation. The following is a brief description of each:

Jan 1, 1963

By S. K. Basu, H. H. Kellogg

THE physical-chemical behavior of the system Pb-S-0 is of prime importance to the understanding of lead smelting processes, yet little accurate information is available on either equilibrium or kinetic behavior in this system. This paper is the first report of a program designed to fill gaps in our knowledge of this system. In the total ternary Pb-S-0, the region of greatest metallurgical interest is that bounded by the compositions Pb-PbS-PbS0,-PbO-Pb. Systems richer in sulfur, or richer in oxygen,* than those essentially pure SO2. This conclusion follows from the fact that all systems are in a highly reduced state, since either PbS or Pb is a constituent of all the equilibria. The content of 02, SO3, S2, S6, S8, and so forth, can be shown to be negligible compared to SO, in all such systems.* corresponding to this region can only be obtained at gas pressures exceeding 1 atm, a condition seldom met in lead smelting practice. Not only is the present study limited to condensed phases within this portion of the total system, but it is limited to temperatures at which all phases are pure solids, except for lead, which is liquid. In this limited system the following seven condensed phases are known to exist: Pb(l), PbS(c), PbO(c), PbSO,(c), PbSO,•PbO(c), PbSO4 • 2PbO(c), and PbSO, -4PbO(c). PbO exists in two crystal modifications,' but only the high-temperature yellow form is considered here. Schenck and co-workers2-4 reported the compound PbSO4 3Pb0 to be stable at high temperature, but the more recent work of Lander,5 and the present work, prove that the tetra-basic sulfate, rather than the tri-basic sulfate is stable. Fig. 1 shows the composition diagram for the binary PbO-PbSO2, based primarily on the work of Lander. In this study the univariant boundaries and invariant points existing among these seven condensed phases and the gas phase have been determined. In a ternary system, the phase rule indicates that an invariant point involves the simultaneous equilibrium of five phases—four condensed phases and the gas phase. A univariant relation involves four phases—three condensed phases and the gas phase. The gas phase in the systems studied is The following stable univariant equilibria between SOz and the condensed phases were identified: (a) PbS + 7PbS04 = 4(PbSO, - PbO) + 4SO2 (b) PbS + l0(PbS04 • PbO) = 7(PbSO4- 2PbO) + 4SO2 (c) PbS + 8(PbSO4 • 2PbO) = 5(PbSO4 . 4PbO) + 4SO2 (d) Pb + PbSO, • 4PbO = 6PbO + SO2 (e) 3PbS + PbSO4 . 4PbO = 8Pb + 4SO2 (f) 3PbS + 16(PbS04 PbO) = 7(PbSO4 . 4PbO)+ 12SO2 (g) 2PbS + PbSO,2PbO = 5Pb + 3SO2 (h) Pb + 3(PbSO4 . 2PbO) = 2(PbSO,. 4PbO) + SO, Of these eight univariant equilibria, five were measured in this work (a, b, c, d, and g) and the behavior of the other three (e, f, and h) was calculated by thermodynamic analysis of the measured data. Two invariant points were found corresponding to simultaneous equilibria as follows: Point 1: PbS, PbSO4PbO, PbSO4.2PbO, PbSO, - 4PbO, and SO2 Point 2: Pb, PbS, PbSO, . 2PbO, PbSO, - 4PbO, and SO2, From the measurements it was also possible to calculate the thermodynamic properties of the three basic sulfates of lead at 298.16°K. EXPERIMENTAL Apparatus—The experimental method consisted of the measurement of the gas pressure exerted by a given reaction mixture at a given temperature. An iridium crucible was used to contain the reaction mixture. There was no evidence of attack of the iridium,* but after use at high temperature for a week

Jan 1, 1961

By Pradeep K. Rohatgi, David N. French, Surendar M. Jain, Clyde M. Adams

The effect of solute concentration and diffussivity on dendritic solidification of dilute binary aqueous solutions has been investigated; chlorides of sodium, potassium, lithiurn, and hydrogen were used as solutes. Dendrite spacings were measured in spherical droplets and in unidirectionally solidified specimens. In the droplets, the freezing rate is uniform over the entire specimen and remains constant from the beginning to the end of solidification. In the unidirec-tionally frozen specimens the freezing rate varies within a given volume of liquid during the solidification cycle; in addition, it varies with location uithin the specimen. Mass transport analysis has been used to calculate the supersaturation, AC, supercooling, AT, and transcerse growth velocity, V , of ice dendrites during solidijication from the dendrite spacings measured in the droplels. The ice dendrite spacing in a given solute increases lineary with the solule concentralion at a fixed freezing rate. The ualues of AC, AT, and V increase with an increase in solule concentration. The value of AT in the aqueous solution is of the same order of magnitude as in Al-Cu alloys of the same concentration; the dendrite spacings in Al-Cu alloys also increase with an increase in solute concentralion. For the jamily of aqueozrs solulions incestigaled, the dendrite spacing increases linearly with solute diffusivity at fixed values of concertralion and freezing ,rate. The values of ?C and ?T decrease, whereas the value of V increases with an increase in solule diffusicity. The measured dendrite spacings , L, can be expressed by the relatiun: L = K;(dfa/db) 4 K2C +K3D - K4 where dfs/d? is-change in fraction solid with time (freezing rate), C is solute concentration, D is solute diffusivit K1 = (14 * 4)pmin1'2, K2 = (70 ± 10) pl (moles)- K3 = (24 r 3) . l05 psec (cm)-~. K. = -132 ± 10) 1. FREEZING of solutions is almost always an ehunmix-ing" process because the composition of crystallizing solid generally differs from that of the parent liquid. " Solute concentration and transport are therefore in]portant considerations in solidification of solutions. The influence of these factors on the dendritic solutions produced from metallic solutions is of practical significance since the properties of the solid aggre-gate are often strongly influenced by dendrite spacing.''' Alexander and Fthines3 found that dendrite spac- ings generally increase with solute concentration in several metallic systems. Michael and Bever1 have observed an increase in a aluminum dendrite spacings in dilute A1-Cu alloys. Rohatgi and AdamsJ have reported a linear increase in a aluminum dendrite spacings with increasing copper contents up to 28 pct in A1-Cu alloys. Bolling and Tiller"' have theoretically examined the effects of solute concentration and diffusivity on the growth of cells and dendrites. Their analysis of dendritic growth assumes a steady-state growth and the maximum possible velocity for dendrite propagation. In addition, the quantitative analysis is restricted to dendrites of rotational symmetry and is therefore not directly applicable to the plate-shaped dendrites of ice obtained in the present study. There are practically no experimental observations of the effect of solute diffusivity on dendrite spacings in metallic systems. The reason appears to be the lack of experimental data on solute diffusion coefficients in liquid metallic solutions. The present work is concerned with the effect of solute concentration and diffusivity on dendritic solidification of dilute aqueous solutions: the solutes examined are potassium chloride. sodium chloride, lithium chloride. and hydrogen chloride. There were several reasons for selecting these solutes. The variation of dendrite spacing with freezing rate in these solutiolls is similar to that observed in A1-Cu alloys.8 These aqueous solutions have almost identical phase diagrams at dilute concentrations. Fig. 1. and the diffusion coefficients show very little variation with solute Concentration.9,10 Dendrite spacings were measured as a function of freezing rate. solute concentration. and solute diffusivity. Dendrite spacings were measured in two different types of freezing systems. droplet and unidirectional, respectively. In the droplet freezing system

Jan 1, 1970

By Robert E. Green, Robert A. Swanson

Ultrasonic attenuation and stress were measured simultaneously as a function of strain for aluminum single crystals tested in compression. The propagation mode and polarization of the ultrasonic waves were chosen with reference to the theoretical analysis presented in Part I. Good experimental agreement was found with this theory and with earlier experimental work in tensile tests. Support is given to the contention that ultrasonic -attenuation measurements are much more sensitive to the early stages of plastic deformation than are conventional stress -strain measurements. Dislocation meclzanisms are suggested which are compatible with both the present and the earlier experimental observations. A brief historical introduction of previous work concerned with the study of dislocation motion by ultrasonic-attenuation measurements has been given in Part I. The purpose of the present experimental investigation was to make use of the theoretical considerations from Part I in order to gain further knowledge concerning dislocation motions during plastic deformation. Emphasis was placed on the choice of propagation modes and polarization of the waves, such that interactions between these waves and dislocation movement on a specific slip system could be investigated. EXPERIMENTAL PROCEDURE Since the primary concern of this investigation was dislocation damping, other sources of damping were eliminated as much as possible. The test specimens were 0.5-in.-diam single crystals of 99.99+ pct pure aluminum grown from the melt by a modified Bridgman technique. Ultrasonic-attenuation measurements were made at a frequency of 10 megacycles per sec using a Style 56A001 Ultrasonic Attenuation Comparator manufactured by Sperry Products Inc. after a design by Chick, An- derson, and Truell.1 At this frequency the particle vibrations are essentially adiabatic and thermo-elastic damping should be absent. This frequency was selected since it was one of the frequencies used by Hikata et al.2 n conjunction with tensile tests on aluminum crystals, thus allowing direct comparison with this work. The use of quartz-crystal transducers insures that the amplitude of vibration is not sufficient to cause the break away of the dislocation loops from weak pinning points. The quartz-crystal transducers used all possessed a resonance frequency of 10 megacycles per sec and were thin circular discs 0.375 in. in diameter. X-cut crystals were used to generate the longitudinal waves and AC-cut crystals to generate the transverse waves. Aluminum was chosen as the basic material because it is a typical fcc metal whose deformation behavior is well-known and because the most recent work at the time the present research was initiated was that by Hikata et al. who used aluminum. The present tests were run in compression to see if such tests could be satisfactorily run in compression without being severely masked by grip effects.. A second reason was to compare the results in compression with those of the tension experiments of Hikata et at. Finally, shorter specimens could be run in compression with less over-all damping than in tension. All of the aluminum-crystal test specimens used were oriented for plastic deformation by single slip; i.e., they possessed the orientation having a maximum Schmid factor of 0.5. Because of the well-known time dependence 3 of plastic strain at constant stress, the test specimens were subjected to a quasi-static loading. Previous investigations4-' have indicated that attenuation after plastic deformation is also time-dependent, so any continuous loading of the specimen would show that changes in attenuation were also a function of strain rate. By loading the specimen to a given stress level and holding it constant until the recovery process was essentially complete, the time dependence was eliminated. The quartz transducer was permanently bonded to the aluminum crystal using Eastman 910 cement. Excess cement was removed from around the quartz with DMF (dimethyl formamide). Eastman 910 was found to be far superior for bonding, especially with regard to the shear-wave transducer, since it formed a solid bond which readily supports shear-wave propagation. The solid bond formed by the Eastman 910 cement also insured that the quartz

Jan 1, 1964

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. C. Winegard, J. R. Carruthers, A. Plumtree, L. R. Morris

The unidirectional solidification of dendrites containing central twin planes was studied in A1-Ti alloys. Once nucleated, the twinned dendrites are a Twore ejficient form for solute redistribution and therefore grow in preference to the normal columnar dendvites. Comparison of these twinned dendrites to adjacent colunmar dendrites by means of decanting experinzents and electron-probe rnicvoarmlysis indicates that these special dendrites grow with less undercooling than normal dendrites. These findings are further supported by the effect of forced convection on the dendrite morphologies. COMMERCIAL semicontinuous cast ingots of most aluminum alloys frequently exhibit large grains which appear to be composed of hundreds of parallel, continuous, thin lamellae. This structure has been termed "basaltic",' "fiederkristall", or, commonly, "feathery grain". The lamellae are 'about 100 p thick, several inches long, and each lamella contains a central (111) coherent twin boundary. The feathery grain has been reported to have a (112) direction2 and a (110) direction4 in the twin plane parallel to the casting direction, in contrast with the usual columnar structure where a (100) direction predominates. Aust et uZ.~ proposed that the twin boundaries were growth twins nucleated by stacking faults on the octahedral planes. chalmers6 has suggested that feathery grain may grow by a re-entrant edge mechanism, as proposed by wagner7 for twinned dendritic growth in germanium. Cahn et ~1.~ have concluded that the occurrence of feathery grain is evidence of some form of lateral layer growth rather than the atomically continuous growth normally observed in metals. The postulates by Chalmers and Cahn would seem to be contradicted by the work of Nakao~"' who showed that feathery grain only occurs when growth rates are high and the aluminum contains some solute. Specifically, Nakao found that in order to obtain feathery grain, in small castings solidified unidirec-tionally upward, the rate of growth must be above 2.4 cm per min and a critical solute concentration must be present. Below this solute concentration the grain structure was totally columnar. The critical solute concentration was found to be approximately: 0.04 wt pct Ti, 2 wt pct Cu or Mg, and 8 wt pct Zn. As pointed out by Chalmers it is not obvious why a twin-plane re-entrant edge mechanism would occur in aluminum which is thought to have a diffuse solid-liquid interface. The present experiments were undertaken to determine the growth mechanisms in- volved and to study the solute segregation in more detail. EXPERIMENTAL PROCEDURES Alloys ranging in composition from 0.05 to 0.23 wt pct Ti* were prepared from 99.9 pct pure Ti and 99.993 pct pure Al. Two-hundred-gram samples of A1-Ti binary alloys were solidified unidirectionally and vertically upward from a water-cooled copper base, in a heated insulated mold. The 1-in.-diam, 6-in.-length mold was made of Marinite (manufactured by Johns-Manville Co.). The mold was attached to a 24-in. pivoted arm such that by dropping a weight the mold was rotated 180 deg, throwing the liquid metal from the solid. In this way, the solid-liquid interface was revealed by decanting. A sketch of the decanting mold is shown in Fig. 1. The alloy was poured into the mold at temperatures ranging from 680" to 750°C, partially solidified by water cooling from the base, and decanted after a measured time interval. Growth rates for each metal-pouring temperature were calculated from solidification-time vs length solidified curves. Temperature gradients in the melt were measured using four No. 34 gage thermocouples which protruded into the mold cavity. Grain orientations were determined by X-ray diffraction using Laue back-reflection techniques. Grain substructures were examined metallographically, using polarized light, by applying a thin epitaxial anodic film to polished sections after the method of Hone and pearson." Titanium micro segregation was measured by electron-probe microanalysis using a NORELCO AMR/~ with a mica crystal and proportional-flow counter. Several of the cast samples exhibited feathery and columnar dendrites growing in the same direction and

Jan 1, 1967

By D. F. Stein

In spite of the apparent usefulness of autoradiography in demonstrating segregation, it has had very limited success in demonstrating grain boundary segregation. Because of this limited success, a model system amenable to mathematical analysis was devised to determine which variables in the experiment are most important. As a result of these calculations, it was concluded that autoradiograPhy is a rather insensitive technique to measure grain boundary segregation. The range (energies) of the emitted particles (ß and a) must be low, and the concentration of the radioactive speczes at the grain boundary must be (in general) two or three orders of magnitude greater than the concentration within the grain. Because of these very restricted conditions , the limited success of the technzque is not surprising. In spite of the apparent usefulness of autoradiography in demonstrating segregation, it has had very limited success in demonstrating grain boundary segregation. Sulfur segregation in iron1 and possibly polonium segregation in Pb-5 pct B1 2 alloys are the only autoradi-ography experiments that have demonstrated segregation to grain boundaries in metals without the formation of a second phase. Segregation to a boundary without the formation of a second phase is often called Gibbs' absorption and is discussed by McLean in Chapter 5 of Ref. 10. There are several394 experiments showing grain boundary diffusion of a radioisotope, but this type experiment is not representative of equilibrium between the concentration of an element at a grain boundary and that in bulk, so it will not be discussed in this paper. In an attempt to determine if temper embrittle ment of low-alloy steels was associated with segregation of antimony to grain boundaries, a program to use auto-radiography (using Sb-125) was initiated. Even though other measurements strongly suggest that segregation is occurring during embrittlement, no evidence of grain boundary segregation was observed in the auto-radiography experiments. An attempt was also made to detect segregation of carbon (using C-14) to grain boundaries in iron during slow cooling. There is again strong indirect evidence7 that segregation occurs during such a treatment, but the autoradiography experiment gave no evidence of such segregation. Because of the failure of these experiments and the general lack of success by our metallographic unit in measuring grain boundary segregation using autoradi-ography, a model system amenable to mathematical analysis was devised to determine which variables in the experiment are most important. MODEL SYSTEM The model system is illustrated in Figs. 1 and 2. It is a semi-infinite bicrystal with a single grain boundary perpendicular to the top face. The width of the grain boundary, W, is defined as the region to which segregation has occurred and it is assumed that this region is of constant composition. The assumption of an infinite dimension is for mathematical reasons but the results of such an analysis (as will be demonstrated later) are valid for even very small specimens. It also is assumed that the measurement is not limited by means of detecting the radiation (photographic emulsions, counters, and so forth) but that the means of detecting radiation is linearly sensitive to the radiation and has infinite resolving power. The distance y is the perpendicular distance from the center of the grain boundary to the point at which the background radiation is measured and x is the integration variable. CALCULATION FOR BETA PARTICLES Two values of the intensity of radiation will be calculated, the intensity at the center of the grain boundary and the intensity far from the grain boundary. The radiation at the center of the grain boundary can be calculated in the following way. Assume a grain boundary of width W having a uniform concentration equal to Cgb + Cb where CGb is the excess concentration of the element under consideration at the grain boundary and Cb is the bulk concentration. The intensity of radiation, IgB, at the center of the grain boundary, is a consequence of the amount of radioactive material, decay rate, absorption, and geometrical factors which can be represented mathematically by the following expression:

Jan 1, 1968