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By A. R. Troiano, A. B. Greninger

There is need for an adequate working hypothesis that would describe at least qualitatively the crystallographic mechanism for the transformation from austenite to martensite in steel. A general theory would not only be of great assistance in the correlation of existing data and in planning future experimentation, but would also form the basis for an eventual explanation of the property changes that accompany lattice transformations. The mechanism of martensite formation described in the following pages is the outcome of two new experimental determinations: (1) the accurate evaluation of the lattice relationship between austenite and individual crystals of martensite, and (2) the measurement and analysis of the change in position that a volume of austenite undergoes when it transforms into a crystal of martensite. For this latter study, the stereographic analysis of shear was employed; this method greatly simplifies the solution of lattice-shear problems, and some space is devoted to its description. Lattiice Relationships and Habits PREVIOUS WORK The lattice relationships between austenite and martensite in carbon steels have been studied by Kurdjurnow-and Sachs,' and by Wassermann;2 and in iron-nickel alloys by Nishiyama.3 Wassermann,2 and Mehl and Derge.4 The studies by Kurdjumow and Sachs and by Wassermann were made on single (austenite) crystals of quenched 1.4 pct carbon steel, and the results of these two independent studies agree closely with the postulated lattice relationships: (III)r||(0ll)a [101]r [111]a [1] Both Nishiyama and Wassermann worked with an alloy of iron plus 30 pct nickel (all austenite at room temperature), and "martensitic alpha" was formed by cooling in liquid air. They agree that the lattice relationships for these conditions are: (lll)r||(011)a [112]r[011]a [2] Mehl and Derge worked with a range of iron-nickel alloy compositions centered about 30 pct nickel. They concluded that when the transformation takes place near room temperature or above, relationship [l] holds, but if the same specimen is made to transform at -195°C, relationship [2] obtains;intermediate temperatures evidently produced a combination of these two relationships. Sachs and co-worker~,1,7 as well as Nishiyama,3 have proposed transformation mechanisms for martensite formation.* Both of the mechanisms picture the transformation as initiated by shearing movements along the octahedral [Ill] plane of austenite, followed by suitable expansion and contraction to complete the transformation. These mechanisms have been described and commented upon by Mehl, Barrett, and Smith,8 Mehl and Derge,4 Wassermann,2 and others, and generally accepted by investigators in this field. Greninger and Troiano9 have recently published the results of a detailed study of the shapes and orientation habits of martensite crystals in plain-carbon and nickel steels. They found that, contrary to previous assumptions, martensite plates form not along the octahedral planes but along austenite planes of very high indices; these results were in line with those of previous studies of martensite reactions in nonferrous alloy systems by Greninger and coworkers.6,10 Greninger and Troiano concluded that the transformation theories of Kurdjumow and Sachsl and of Nishiyama3 are untenable. Phragmén11 reached a similar conclusion. EXPERlMENTAL METHODS The object of this particular study was the evaluation of (1) lattice relationship between austenite and martensite, and (2) relationship between the martensite lattice and the martensite plate. The technique used for solving these problems was similar to that used by Greninger6 on martensitic structures in 8 copper-aluminum alloys. Briefly, the method consists of grinding and polishing a specimen on a surface parallel to an individual martensite plate and thus exposing a single martensite crystal for an area of l to 3 mm. The orientation of this exposed martensite crystal is then determined by means of a back-reflection Laue X ray pattern.12 Another pattern is obtained from the matrix crystal, and a stereo-graphic plot of data from these two patterns then provides the solution to the problem. It is necessary to repeat this process on several crystals in order to determine whether or not the solution is unique.

Jan 1, 1950

By Frank S. McKenna, Myron A. Pugacz, Clarence E. Jackson

THE notched-bar impact test has proved worth while in certain applications as a test for control of the quality or the heat- . treatment of steel. In view of the serious thought that even so simple a test as the tensile test, has evoked during the past years, it is not surprising that the notched- bar impact test should have inspired much experimental work. The correlation of the great number of data has not been successful, although steady progress has been made toward a better understanding of this test. Progress has been made, especially, in the isolation of the effects of the many variables that control the results. The stress system imposed on a specimen with a notch is so complicated and un- predictable that no simple evaluation of the test has been possible. Because of this uncertainty, many engineers hesitate to use the notched-bar impact test, and this attitude may well continue until a better understanding of the effects of the variables in the test are available. Without doubt, any additional data that may be presented should be accompanied by as complete a description of the details of test as possible, so that it may be added to the general fund of information that is to serve as the basis for the theory of the notched-bar impact test. The many factors that may control the test results have been pointed out repeatedly. The importance of the effect of the type and dimensions of the specimen has been recognized. Most of the work reported by American investigators has been limited to small- size (Charpy) specimens tested as a simple beam; two types of notches (Fig. I) have been commonly used. Considerable data have also been presented by many investigators using a small specimen tested as a cantilever beam; this commonly being called the Izod test. Here, however, a shear component of stress makes the stress system even mare complex than that present in the simple beam type of test, hence a critical analysis is difficult. Much work has also been reported by investigators using the tension type of specimen. A second variable that must be con- trolled is the testing temperature. An indication that the tests were performed at room temperature is not sufficient, since in many steels a variation of a few degrees in the actual testing temperature may be sufficient to give an entirely different range of results. Other factors. such as the com- position and condition of the material being tested and the speed of test, should also be considered. Many investigators have contributed data and theoretical discussions on the problems encountered in notched-bar test-

Jan 1, 1944

By Jean Howard

RECENT attempts to produce secondary recrystalli-zation in high-purity iron have given conflicting results. Coulomb and Lacombe1'2 did not find it but Dunn and Walter3,4 did. The latter workers have stated that (100) [001] and/or (110) [001] orientations develop depending on the oxygen content of the annealing atmosphere. This Technical Note records results which are in agreement with Dunn and Walter in so far as it shows that secondary recrystallization can be produced in high-purity iron, but does not confirm that both types of orientation are obtainable. Similar observations have been made on chromium-iron and molybdenum-iron, although when this technique is used on 3 1/4 pct Si-Fe, both types are obtained as in the work of Dunn and alter.' Pure iron strip was cold-rolled from sintered compacts prepared from Carbonyl Iron Powder-Grade MCP of the International Nickel Co. (Mond) Ltd. The powder contains about 0.5 pct 0, 0.01 pct C, 0.004 pct N, (0.002 pct S, $0.005 pct Mg and Si, and 0.4 pct Ni—that is, it is substantially free from metallic impurities other than nickel, which is thought to be unimportant in the present work. The iron powder was (a) pressed at 25 tons per sq in. into blocks measuring 3 by 1 by 0.3 in., (b) deoxidized in hydrogen (dewpoint -60°C) by heating first at 350°C and then at 600° C until the dewpoint returned to -60°C at each temperature and (c) sintered in hydrogen (dewpoint -40°C) at 1350°C for 24 hr. (when dewpoint is referred to in this Note, it is the value as measured on the exit side of the furnace). The sintered compacts were cold-rolled to 1/8 in., annealed in hydrogen (dewpoint -60°C) at 1050°C for 12 hr and cold-rolled to 0.004, 0.002, and 0.001 in. with inter-anneals at 900°C for 5 hr and a final reduction of 50 pct. Final annealing of strip between alumina or silica plates at 875" to 900°C in hydrogen with dewpoints of -20°, -55" and -80°C produced secondary grains with the (100) in the rolling plane; the extent of secondary recrystallization was greatest when the dewpoint was -55°C. Annealing in a vacuum of 2 x 10"5 mm Hg at the same temperature produced no secondary recrystallization at all. With strip thicker than 0.002 in. very few secondary crystals developed whatever the conditions of annealing. Using a processing schedule somewhat similar to that described above, secondary recrystallization was produced in two bcc alloys of iron, viz. 80 pct Fe + 20 pct Cr and 96 pct Fe + 4 pct Mo. The former was reduced to final thicknesses of 0.001 to 0.004 in. and the latter to final thicknesses of 0.001 to 0.016 in. With the chromium-iron, a final anneal at 1250°C (found to be the most effective temperature for developing secondary crystals in the 0.004-in material) with a dewpoint of -25°C produced a greater degree of secondary recrystallization than with dewpoints of -50°C or -20°C. Secondary crystals developed in strips of all thicknesses from 0.001 to 0.004 in. Final annealing in vacuum produced no secondary crystals at all. For the molybdenum-iron a temperature of 1200°C was most effective. It was found that a dewpoint of -50°C during the final anneal gave better results than a dewpoint of -25 "C on the 0.008 in. material. Final annealing in vacuum gave slightly worse results than annealing in hydrogen with a dew-point of -50°C. Secondary crystals were developed in strips of all thicknesses up to 0.008 in. The experiments show that the extent of secondary recrystallization is a maximum for certain critical values of oxygen content of furnace atmosphere and annealing temperature, and that these values are different for different alloys. The thinner the material, the less critical these values are. The general conclusions are that secondary recrystallization can be obtained in high-purity iron, chromium-iron, and molybdenum-iron, using a processing schedule similar to that which will cause the phenomenon to take place in high purity 3 1/4 pct Si-Fe. Unlike the silicon-iron, however, only the (100) (0011-- orientation has been produced in these alloys, irrespective of the temperature of final annealing and the oxygen content of the furnace atmosphere. The information used in this Note is published by permission of the Engineer-in-Chief of the British Post Office.

Jan 1, 1962

FOREIGN WAR RELIEF COMMITTEE Chairman, MRS. JESSE SCOBEY The task of the committee since Oct. 17, 1918, has been to stimulate and foster interest in the work of the Dispensary in France, to aid and further the work, and to that end has centered on the inauguration of an "Engineers' " day, once a week, at the headquarters of the American Fund for French Wounded, where members of the Auxiliary might join in sewing for this "Dispensary of the New York Section of the Woman's Auxiliary to the A. I. M. E.," recently established at Briey, France. Letters and pledge forms asking for workers were sent to all members of the Auxiliary in New York City and vicinity, and a most gratifying response has assured the success of the undertaking. The meetings in December, pending the completion of better working facilities at Fund headquarters, were held at the home of Miss Madeline P. Stone, to whom the committee extends its grateful thanks for her hospitality large, well-equipped room at Fund headquarters has now been assigned to the committee for Tuesday of each week, from 10 a. m. to 5 p. m., with Mrs. Percy E. Barbour of the committee as director of work room. All members of the Auxiliary and others whose interests are with the mining profession will be welcome on "Engineers'" day-Tuesdays-at 73 Park Ave.

Jan 2, 1919

By Donald Barton

THE theory of gravitation is based on Newton's law that any two bodies exert a mutual attraction which is proportional to the product of their masses and inversely proportional to the square of the distance between them; i. e. A= K MM/R2 (1) where K is a constant, M and m are the respective masses of the two bodies, and R the distance between them. In the earth's gravitational system, the earth is one of the bodies; the other may be any body within or without the earth. In theoretical discussions and calculations in regard to gravity, that other body usually is taken as a unit of mass: in the C. G. S. system, a body of one gram in mass.

Jan 1, 1928

By John Vasey

A shaft of 1690 m depth is currently being sunk to exploit a large copper sulphide orebody. The primary crusher chamber, main pump chamber and the other excavations on the crusher level were developed from the shaft during the sinking operation. The maximum principal stress is horizontal and has a magnitude twice that of the vertical stress. It increased linearly with depth and on the elevation of the crusher level, 1613 m below surface, the stresses induced by mining can exceed the strength of the rock. The development of a workable crusher level layout, and a crusher chamber design and support system are described. Excavation and support of the workings are detailed and a comparison of expected and actual results is made.

Jan 1, 1983

By Thos Gibson

THE object of taxation is the raising of a revenue. Unless a tax accomplishes this, it is a failure. The right to take for public purposes a part of the moneys obtained from the carrying on of private enterprises is an attribute possessed only by a lawful government, and may indeed he called the supreme attribute of government. In free, democratic communities this power must of necessity rest upon the consent of the governed. Power implies obligation, hence it is obviously the duty of a government, in framing a system of taxation, to provide one which, while effective in producing a revenue, is also just and impartial. It will be conceded that mines and mining property ought to bear a fair share of the public expenditure. The question is, upon what basis taxation should proceed. Two separate taxing principles are usually contended for: Taxation should be proportionate to the benefits received by the person or property taxed; taxation should be based on ability to pay. A third is sometimes added, taxation should have reference to the extent and value of the natural resources enjoyed. As applied to mining taxation, it is pointed out by those who support the first mentioned basis that, mines being usually situated in rocky and hence sparsely peopled regions, mining companies are frequently obliged to construct roads, railways, telegraph and telephone lines, schools, water and sewerage systems, and many other amenities and conveniences of civilization, the cost of which in regions better suited for agriculture and consequently more thickly populated, has either been defrayed locally, or can be spread over a sufficiently large taxable group of people to materially lighten the financial burden on the mine. The mining com¬pany, it is argued, having made these outlays, should receive credit for, them and be relieved of taxation to a corresponding extent. There may be some force in this contention, but the situation is capable of relief without attempting to place taxation upon so unworkable a basis as the value of benefits received. Who is to be the judge of these benefits, and how are they to be valued? The very existence of a mining company and its ability to carry on business in peace and security, depend on the prevalence of law and order, which is a result of good government. The state provides protection against violence, and courts of law for

Jan 4, 1919

By W. F. Carew, F. A. Crossley

IT has been reported that the Ti-8 pct A1 alloy is ductile as water quenched from 800°C but brittle as annealed at 650 °C." The present, somewhat limited, investigation was undertaken to discover the cause of the embrittlement. In order to evaluate to some extent the continuity of the embrittling phenomenon, alloys of 6, 8, and 10 pct A1 were studied. Subsequent to the completion of most of this work, Ence and Margolin reported that a Ti,A1 phase exists and that two or more unidentified compounds may exist in the Ti-A1 system.' Materials, Equipment, and Techniques The alloys were prepared using Kroll process sponge of 124 Bhn hardness. In addition, some 8 pct A1 material was made with iodide titanium. The sponge-base alloys were prepared as melts of 4 lb or more by double arc melting. The iodide Ti-8 pct A1 alloy was prepared as 200-g buttons. The alloys were forged at temperatures of 980" to 1150°C. Results of chemical analyses are given in Table I. A Baldwin-Southwark 60,000-lb capacity tensile machine, equipped with an autographic stress-strain recorder, was used for the tensile tests. Standard tensile test specimens, 0.252 in. diam, were used. Standard Charwy V-notch impact specimens were tested using a -kiehle machine. specimens were sealed in evacuated Vycor bulbs for heat treatment. Powder samples for Debye-Sherrer anal- ysis were prepared by filing and screening through 325 mesh. The —325 mesh fraction was taken in an effort to concentrate a microstructural constituent assumed to be less ductile than the a phase. The powder samples were stress relieve2 by annealing

Jan 1, 1958

By Michael Tenenbaum, T. L. Joseph

Recent researches on the reduction of iron ores have stimulated interest in the effect of increased pressures within the iron blast furnace. From a physicochemical viewpoint, it seems logical to suppose that the increased pressure would increase the rate of reduction of the iron ore within the furnace. This increased reaction velocity would in turn be reflected in an increase in the output of the blast furnace. Any substantial effect of elevated blast-furnace pressures should accordingly be of both technical and economic interest to the operator. It is doubtful whether it is possible to increase the pressure in the stack of the blast furnace beyond two or three atmospheres without incurring severe mechanical difficulties. The benefits to be procured by elevations in pressure must therefore be restricted to pressures below two, or at the most, three atmospheres. Within this range it would seem both economically and mechanically feasible to modify the present design of the upper portion of the blast furnace to accommodate these more stringent operating conditions. This investigation was undertaken to study the effect of moderate pressures on the rate of reduction of iron ore with hydrogen. The use of carbon monoxide is contemplated for later work. Although any results that are obtained in the laboratory cannot be interpreted directly in terms of large-scale commercial operations, it is possible, through such an investigation, to ascertain the order of magnitude of the effects of higher pressure. A more quantitative conception of the effects that would result from the use of increased pressures in the modern blast furnace is needed. In some recent work, Diepschlagl found that, all other factors remaining constant, the degree of reduction of iron ores was much greater when carried out under pressure. Pressures as high as seven atmospheres were used. The degree of reduction was determined from the ferrous and ferric iron in the sponge iron. Results were obtained using both carbon monoxide and hydrogen at temperatures of 400°, 600° and

Jan 1, 1939

By Michael Tenenbaum, T. L. Joseph

Recent researches on the reduction of iron ores have stimulated interest in the effect of increased pressures within the iron blast furnace. From a physicochemical viewpoint, it seems logical to suppose that the increased pressure would increase the rate of reduction of the iron ore within the furnace. This increased reaction velocity would in turn be reflected in an increase in the output of the blast furnace. Any substantial effect of elevated blast-furnace pressures should accordingly be of both technical and economic interest to the operator. It is doubtful whether it is possible to increase the pressure in the stack of the blast furnace beyond two or three atmospheres without incurring severe mechanical difficulties. The benefits to be procured by elevations in pressure must therefore be restricted to pressures below two, or at the most, three atmospheres. Within this range it would seem both economically and mechanically feasible to modify the present design of the upper portion of the blast furnace to accommodate these more stringent operating conditions. This investigation was undertaken to study the effect of moderate pressures on the rate of reduction of iron ore with hydrogen. The use of carbon monoxide is contemplated for later work. Although any results that are obtained in the laboratory cannot be interpreted directly in terms of large-scale commercial operations, it is possible, through such an investigation, to ascertain the order of magnitude of the effects of higher pressure. A more quantitative conception of the effects that would result from the use of increased pressures in the modern blast furnace is needed. In some recent work, Diepschlagl found that, all other factors remaining constant, the degree of reduction of iron ores was much greater when carried out under pressure. Pressures as high as seven atmospheres were used. The degree of reduction was determined from the ferrous and ferric iron in the sponge iron. Results were obtained using both carbon monoxide and hydrogen at temperatures of 400°, 600° and

Jan 1, 1939

By Thomas Read

AMONG the large number of deep mines in the world there are several which do not differ much in depth. The St. John del Rey mine, in Brazil, has reached a vertical depth of 6726 ft. below the top of its shaft; miners enter it, however, through an adit which intersects the shaft 324 ft. below its top, wherefore it might be said that the mine is really only 6400 ft. deep. In the Kolar gold field of India there are a number of deep shafts, one of which reaches to a vertical depth of 6140 ft. below surface. In South Africa also there are a number of deep shafts, the Village Deep being 6100 ft. early in 1921. The City Deep, Ltd., proposes to sink to a depth of 7000 ft. but pre-sumably by the time it does so the St. John del Rey will be deeper than that, since it has been increasing in depth at an average rate of about 150 ft. per year. The deepest shaft in the United States, the Tamarack No. 5, although it is only 5308 ft. deep, actually approaches nearer to the center of the earth (4100 ft. below sea level, as against 3958 ft. , at St. John del Rey). The deepest workings in the Calumet & Hecla go down to 4600 ft. below sea level. The St. John del Rey is not only the deepest, mine in the world, but it also is worked by the oldest registered English mining company, which was organ-ized in 1830 to work a mine at a considerable dis-tance from this one. That mine proved unprofitable, and in 1837 operations were transferred to the. deposit now under discussion, where operations have been prac-tically continuous ever since.

Jan 6, 1923

By L. C. Kern

This paper presents information on the use of a new propping agent (malleable aluminum particles) which has been used successfully for producing high-conductivity fractures. The conductivity of a packed fracture depends on the width of the fracture as well as the permeability of the propping material. It is significant that the flow capacity of a propped crack is often increased many fold by propping the crack with a sparse distribution of particles. However, the flow capacity of a sparsely propped crack can be limited by two phenomena: (I) crushing of the propping particles, and (2) embedment of the propping particles in the formation walls. Malleable aluminum particles exhibit interesting properties which tend to overcome these limitations. As high loads are applied to the particles they will deform slightly, rather than shattering. The deformation results in a greater bearing area against the formation wall. This reduces the stress on the particle and reduces particle penetration into the formation. The behavior of aluminum particles under load and the bearing capacities of serveral formation rocks have been measured in the laboratory. By properly using these data, as explained in this paper, the flow capacities of aluminum-propped cracks can be calculated for a variety of conditions. Aluminum particles have been used successfully in the field to prop fractures. Where high-conductivity fractures were needed, the aluminum-propped fractures have given greater well stimulation than could have been expected for conventional fracturing processes. INTRODUCTION The purpose of a hydraulic fracture treatment is to create a conductive channel from the wellbore out into the oil or gas formation. The word conductive is emphasized because we believe that the fracture conductivity (flow capacity) is one of the most important factors influencing fracturing results. Previous papers have pointed out the additional well stimulation that can sometimes be achieved by increasing fracture conductivity. Several years ago, we investigated in some detail the effect of fracture conductivity on productivity increases to be expeced from vertical fractures. Both electrical analog and theoretical studies of unsteady-state flow behavior were made. A discussion of the electrical analog equipment and some of the results of the study were given in a previous paper' by Dyes, Kemp and Caudle. Further details were given recently by McGuire and Sikora.5 Fig. 1 shows the remarkable influence of relative fracture flow capacity and length on well stimulation. Briefly, the study indicates the following. 1. High-permeability formations require high-conductivity cracks for best results. 2. The longer the crack, the higher the fracture conductivity required for best results. 3. If the conductivity of the crack is very large compared to the formation (i.e., flow is not being limited by crack conductivity), then the longer the fracture, the better will be the results. Judging from recently published articles,1,314 there is current interest in methods for obtaining high fracture conductivities. Hence, we would like to present in this paper a discussion of a new fracture propping process (use of aluminum particle) which we have used successfully to obtain highly conductive fractures. There are several factors which influence the conductivity of a propped crack. Conventional fracturing techniques frequently result in a crack completely packed with fracturing sand. For such conditions, the crack conductivity is the product of the width of the packed fracture and the permeability of the propping material. It is significant that a large increase in conductivity sometimes can be obtained by propping with particles which are distributed sparsely (less than a

By B. G. Bunting, J. H. Johnson, H. J. Schock

This paper describes an experimental method for monitoring diesel-generated exhaust gas pollutants in a deadended drift to assess the effect of control approaches. Experiments were conducted to determine the relative merits of these ventilation configurations: no auxiliary ventilation, induction ventilation at the entrance to the drift, and ventilation of the dead-ended drift with positive displacement tubing. The drift used in this experimental work was approximately 32 m long and slightly downsloping, with an everage height and width of 2.4 and 8.6 m, respectively. For this drift, it was found that ventilation with positive displacement tubing provided the best removal of diesel-generate pollutants. Induction ventilation appeared to be the least effective of the three methods examined.

Jan 1, 1982

By Willard L. Hunter

Four solvent extraction systems were studied to determine their efficiency jor extraction and separation of tantalum and columbium. Aqueous feed solutions of varying HF-HCl concentrations and metal content were contacted with equal volumes of cyclohexanone, 3-methyl-2-butanone, and 2-pentanone and solutions of varying HF-H2S04 concentrations were contacted with equal volumes of 2-pentanone. One multistage continuous test was made in a polyethylene pulse column using cy clohexanone as the organic phase. In each system studied, columbium and tantalum purities in excess of 95 pct with respect to each other were obtained in single-stage tests at low acidities in the feed solution. Separation factors ranging from 1700 to 2400 were obtained when rising HF-HCl mixtures in the aqueous phase. Best results were obtained when a solution of HF-H2S04 was used as the aqueous phase and 2-pentanone as the organic phase. A separation factor in excess of 6000 was obtained in one stage with aqueous solution concentrations of 2 _N HF and 2N H2S0,. When acid concentrations were increaszd to 52 HF and 10 _N H2S0,, 99.9 pct of the tantalum and 98.2 pct of the columbium initially present in the feed solution were transferred to the organic phase. The separation of columnbium and tantalum obtainable by means of the solvent extraction systems presented in this paper was found to corn -pare favorably with other systems, including the HF-H2SO4-methyl isobutyl ketone system currently used by most producers for the extraction and separation of these metals. TANTALUM and columbium are always found together in minerals of commercial significance, although the proportion of the two metals in ores varies within broad limits. Columbium is estimated to be 13 times more abundant than tantalum. Five methods generally employed for the separat:ion of these metals are: 1) fractional crystallization (the Marignac process),2 2) solvent separation, 3) fractional distillation of their chlorides, 4) ion exchange, and 5) selective reduction. Of these methods, the one currently used by industry to the greatest extent is that of solvent separation. One of the early technical developments in solvent separation of tantalum from columbium was reported by the Bureau of Mines: the HF-HC1-methyl isobutyl ketone system; data were presented for both laboratory and pilot-plant experimentation.3 Of twenty-eight organic solvents tested for their ability to extract tantalum from an HF-HC1 solution of columbium and tantalum, 3-pentanone (diethyl ke-tone), cyclohexanone, 2-pentanone, and 3-methyl-2-butanone were chosen for further study. Data on the HF-HC1-diethyl ketone system has been published4 and data describing the use of cy clohexanone, 2-pentanone, and 3-methyl-2-butanone as the organic phase are included in this report. RAW MATERIAL The source of tantalum and columbium oxides for this study was ('Geomines" tin slag from the Manono Smelter, Cie Geomines, Gelges, S.A., Congo. In order to extract the valuable Ta-Cb content, the slags were carbided, chlorinated, and the sublimate from chlo-rination was hydrolized and washed free of chloride with water. The washed material was air-dried and stored in a stoppered container. Throughout the paper, "feed material" refers to this mixture of hydrated oxides which was employed because of its high solubility in aqueous solutions. Typical analysis of the hydrated oxides is shown in Table I. I) HF-HC1-CYCLOHEXANONE SYSTEM Batch Separation. Effect of Acid Concentration. To determine the effect of varying the acid concentration upon the transfer of tantalum and columbium, a series of tests was made in which approximately 2.5 g of feed material was added to 25 ml solutions of 2, 4, 6, 8, and 10 N HF and 0 through 5 N HC1. Tantalum pentoxide concentration of the solu%ons was approximately 21 g per liter and columbium pentoxide was 14 g per liter. These starting solutions were shaken with equal volumes of cyclohexanone in 100 ml polyethylene bottles for 30 min. The phases were carefully separated in 125 ml glass separatory funnels. The time of contact of the solutions with the separatory funnels was kept at a minimum to reduce silica contamination. The measured phases were separated into 400 ml polyethylene beakers and the metal contents of each were precipitated by addition of an excess of ammonium hydroxide. Precipitate from each phase was filtered on ashless filter paper, ignited at 800" to 1000°C for 45 min, weighed, and analyzed by X-ray fluorescence.5 Data tabulated in Table I1 and illustrated in Fig. 1, show that maximum separation of tantalum from columbium for each HF concentration was obtained with no HCl present. The purest tantalum product was obtained with some HCl present. The highest separation factor was obtained at 2 N HF and

Jan 1, 1970

By R. J. Wygal

A method is presented by which homogeneous, isotropic, and reproducible aggregates of particles such as glass beads, sand, ground glass, etc., may be prepared simply and quickly by using a "particle distributor". Several applications of the packing method to the construction of model reservoirs are described. The flow characteristics of these packings me given. Some factors which limit the usefulness of unconsolidated packs for simulating reservoir rock are overcome through artificial cementation of the aggregates. INTRODUCTION Many laboratory studies of porous media are based on experiments using test packs of sand, glass beads and other granular materials. More confidence can be had in the results of such studies if the test packs are known to have uniform properties throughout, to be mechanically stable and to be accurately reproducible. This paper presents a method by which such packs of a variety of shapes and sizes may be constructed using a particle distributor. Some factors which limit the usefulness of unconsolidated packs as a means for simulating reservoir rock are described. A method of overcoming these limitations, which involves artificial cementation of the packs, is presented. DEVELOPMENT Particles packed by the tamping or vibrating techniques are usually either non-uniform or mechanically unstable. An invention by Currie and Gregoryl overcomes these difficulties to some extent. The invention is based on the use of a stream of falling particles impinging on and passing through a distributor matrix of several layers of closely spaced spheres. The particles are well dispersed by numerous collisions with the spheres. They become homogeneously distributed at some distance below the distributor matrix and at that position are collected in the sample container. This apparatus, however, was found to be ineffective when small particles were used since small particles accumulate on the top surfaces of the spheres. An improved distributor matrix was made, first in the form of a stack of five sieves, and then in the more adaptable form of spaced layers of wire screen. Fig. 1 shows a longitudinal view through a five-layered distributor of eight-mesh wire screen. This device gives excellent results.* Fine particles pass through the distributor with very little hold up. The fine structure of the wire matrix with its many deflecting surfaces ensures good particle distribution. There are no dead areas immediately below the screen as were sometimes observed to occur below a matrix of spheres. Using such a device, 20-30 mesh sands were packed to a porosity of 32.1 per cent at rates varying from 0.17 to 6 lb/rnin. The lowest porosity achieved by tamping small increments of similar sands into a container was 33 per cent. Motion pictures at 3,000 frarnes/sec of the surface of a growing pack of 2-3/4 mm glass beads have helped to show the mechanism by which packs of low porosity are obtained. The beads, although packed at the rate of 5 lb/min, were observed to hit the pack surface singly, for the most part, and at well spaced points of impact. Part of their energy is transferred to surface beads which are thereby

By B. Yarar

Samples of coal from an adit in the Fording River District of British Columbia showed hydrophilic properties between depths of 0-24.5 m (0-80 ft) and was naturally hydrophobic at greater depths. Laboratory experiments indicated that weathered samples (i.e., those mined at 0-24.5 m) could be upgraded by froth flotation at pH32 following slimes removal. The i.e.p. of samples varied regularly between pH = 1.6-4.1, the weathered fractions being at the lower end of the pH scale. These values followed a pattern comparable with the flotation behavior of samples. A patchwise structure for coal surfaces determining the resultant disjoining pressure which in turn determines flotation-non-flotation relationships is postulated.

Jan 1, 1983

By C. A. Stetefeldt

Metallurgical processes cannot be conducted successfully With out the aid of analytical chemistry. The great perfection of Iead smelting in the West, for instance, has only been accomplished by the analysis of ores, fluxes, slags and all products of the furnace. Ores are mixed and fluxed to obtain a slag of desired composition. Account is even taken of the composition of the ashes obtained from the coke. The " muscular " smelter has left the field forever! This state of affairs has been induced by sharp competition, i.e., by a com plete separation of the industries of mining and reducing ores, not by the liberality and wisdom of directors and stockholders to pro vide laboratories and engage chemists, or by their love for scientific investigation. It would be considered absurd, at present, to run a lead-smelter, a blast-furnace for pig-iron, or a Bessemer plant without the assist ance of a well-equipped laboratory and a chemist; but it is con sidered quite sufficient to provide amalgamation- or lixiviation works merely with a crude assay-office, and an assayer who is paid less than a laborer in the mill. In my opinion, this will change in the near future. By the ex clusion of Mexican lead-ores, and their growiring scarcity in the West, smelters have been forced to raise their charges on so-called dry silver-ores, and cannot handle the latter now in such unlimited quantities as formerly. The inevitable result must be that the sur plus of these dry silver-ores, especially those of low grade, will be reduced by processes cheaper than smelbing; and here the introduc tion of lixiviation has an excellent field, provided the muscular lixiviator has an able chemist for an assistant. It is to be regretted that so little analytical work has been done in lixiviation. We know almost nothing of the composition of roasted ores before and after lixiviation; of the constitution of the first wash water and of lixiviation-solutions after prolonged use; of the chemistry of sodium and calcium sulphides; of the col-hposition

Jan 1, 1892

By G. P. Bowman, D. F. Howard, R. K. Saxer, J. R. Myers

This study was undertaken to redetermine the phase diagram of the lead molybdate-bismuth molyb-date salt system. A portion of this diagram was originally determined by Zambonini in 1920, and more recently by Beale. Thermal analysis and X-ray methods were used to define this system. The diagram was found to be a simple eutectic type with an eutectic at 11 mol pet lead molybdate and 634OC. A maximum solid solubility of 6 mol pet was found at the lead molybdate end of the diagram. Solid solubility at the bismuth molybdate end of' the diagram appeared to be quite limited and possibly nonexistent. These results generally agree with those of Beale, but differ significantly from those of Zambonini. MOLTEN salt systems have been vigorously investigated since World War 11. Much of this work has been performed as pure research; however, consideration has recently been given to their possible use as coolants in nuclear reactors. Because of this application and other potential applications, it was decided to reinvestigate the lead molybdate-bismuth molybdate phase diagram. This diagram was originally determined by Professor F. Zambonini of the University of Turin in 1920.' In 1961, a portion of this diagram was redetermined by Beale.2 With the quality equipment and high-purity materials available today, it was expected that discrepancies between the results of this present investigation and Zambonini's work would be obtained. This investigation was conducted in two parts. First, the general shape of the phase diagram was determined by cooling-curve analysis. Next, the primary solid-solution phase at the lead molybdate end of the diagram was investigated by means of X-ray diffraction techniques. EXPERIMENTAL PROCEDURE High-purity lead molybdate, assaying 99.993 pet, and high-purity bismuth molybdate, assaying 99.989 pet, were employed during this investigation.* The results of a spectrographic analysis of the two salts are presented in Table I. Twenty-two experimental compositions were prepared for cooling-curve analysis. Compositions selected are presented in Table 11. Several randomly selected samples were analyzed chemically to check that the compositions of the prepared specimens were within the limit of

Jan 1, 1964

By Michel David

One of the most important questions that arises in ore estimation can be stated as follows: What is the error when one extends the grade of a sample to a certain volume? The theory of regionalized variables, with the concept of extension variance, provides a response to that crucial question for any kind of sample extended to any volume. For the usual "extensions" encountered in current mining practice, some simple results can be derived from that theory which was initiated by Dr. G. Matheron. These results have been applied to a stratiform lead-zinc deposit for which several estimations of grade, tonnage and related precision have been made for a series of grid sizes such as might be used in a progressive exploration program.

Jan 1, 1969

By A. U. Seybolt, F. J. Norton

A standard technique for heat treating small metallurgical samples where no appreciable contamination from the atmosphere can be tolerated is that of sealing small samples in evacuated fused-silica tubes. Since vitreous silica is relatively impervious to diffusion of gases, even at temperatures approaching the devitrification range, around 1100°C, this simple procedure has been very widely adopted as a standard technique in metallurgical research. Many workers have recognized that, with metals of fairly high reactivity, insulation from direct contact with the SiOz envelope is desirable in order to avoid displacement reactions of the type M + SOz-- MOz + Si(in M). It is not so generally known, however, that the 'rate of permeation of oxygen from the air through the SiOz enclosure at tem-

Jan 1, 1964