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By J. H. Lightfoot, Stuart E. Buckley

DEEP drilling has led to the development of numerous pools which yield products consisting predominantly of natural gas accompanied by high-gravity water-white or slightly straw-colored liquid. Yields of this "condensate" or "distillate," as it is commonly called, vary from traces to over a hundred barrels per million cubic feet of gas. The fact that this liquid exists in the reservoir as an integral part of the gas phase and is formed by condensation attending simultaneous reduction of pressure and temperature after its entry into the well was apparently first recognized about 1932.1 The nature of the physical phenomena involved in this condensation was clarified for the petroleum industry in 1933 by a report by Sage, Schaafsma, and Lacey2 of the results of an experimental investigation of the behavior of mixtures of methane and propane. Search of the literature has revealed that the condensation of liquid from gaseous mixtures by isothermal pressure reduction is not a new discovery. Kuenen was led by theoretical considerations to expect such a phenomenon, and in 1892 reported3 the results of experimental verification of his deductions. This was followed by a considerable amount of work on the phase relations of mixtures by Kuenen4,5,6 and by others,7,8 mostly in European universities. Since 1930 investigators in this country have reported experimental data on the properties and behavior of a number of hydrocarbon systems.9-17 It is now generally known that in the presence of natural gas the solubility in the gas phase of the heavier and normally liquid hydrocarbons increases rapidly with increasing pressure above 500 to 1000 lb. per sq. in. Thus, at pressures of 2500 lb. per sq. in. or higher a gas may contain appreciable quantities of hydrocarbons with normal boiling points as high as 600°F., which in turn may be condensed from the gas phase by the reduction of their solubility therein attending pressure reduction. The combined effects of pressure and temperature on condensation and vaporization of mixtures are most readily visualized by the study of phase diagrams. Since the construction, application, and interpretation of such diagrams have been described fully in readily available literature, 18-20 this paper will not review the theoretical aspects of this subject. While the behavior of gas-distillate systems is now clearly understood, at least in a qualitative way, most of the published work deals with the results of laboratory studies of binary systems or of synthetic mixtures of hydrocarbons, and although several systematic investigations of the effects of separator pressure and temperature on the yields of liquid product from gas-distillate wells have been made21.22 it appears that in all cases the limitations have precluded the construction of even approximately complete phase diagrams for naturally occurring systems. There has

Jan 1, 1941

By A. S. Nowick, E. S. Machlin

One of the main criteria used to rate the heat-resisting properties of alloys is stress rupture.' During a stress-rupture test a tensile specimen is held under a constant load at a constant temperature until it fractures. The chief measurement made during this test is the time requird for rupture at the specific test stress and temperature. It was found empirically from a series of stress-rupture tests at a constant temperature that when the logarithm of the time for rupture is plotted against the logarithm of stress a straight line is obtained within experimental error This method of showing stress-rupture data has been adopted by many investigators and the NACA.' By interpolation and extrapolation from these plots, values of the stresses required to rupture the specimens (the rupture strengths) in 10, roo, and 1000 hr are obtained for specific temperatures. Alloys are then rated for a particular application on the basis of their rupture strengths at the rupture life that most nearly represents the application. Inasmuch as stress rupture is an important criterion in rating heat-resisting alloys, it would be advantageous to know the quantitative dependence of the time lor rupture on stress, temperature, composition, and structure. In order to obtain this information, an investigation was made at the NACA Cleveland laboratory during the spring of 1945. The theory of rate processes was used because it has been found to apply to certain processes such as chemical reactions, viscous flow, and creep that occur at a definite rate for given conditions. It was thought that stress rupture was such a process. An equation was derived that gives, for a given composition and structure, the dependence of the time for rupture on stress and temperature. The investigation is part of a general program to provide information that will lead ultimately to the development of better alloys in order that the efliciency and power output of gas turbines used in aircraft propulsion can be increased. Theory The theory of rate processes will first be discussed as a general theory. It will then be shown that if stress rupture of heat-resisting alloys can be treated as a rate process, certain equations must be satisfied. Later sections will then show that these equations are satisfied. General Theory of Rate Processes The theory of rate processes5 developed by Eyring and others has been applied to chemical reactions as well as to other processes such as viscosity of liquids and diffusion. In every case in which rate-process theory can be applied, there is a small subdivision, so that the macroscopic process is the net effect of all the small processes. This smallest subdivision is called the "unit process." For example, in a chemical reaction the unit process is

Jan 1, 1948

By E. F. Ketterer, D. B. Collyer, A. B. Wilder

AISI constructional alloy steels are a series of steels in which a numbering system signifies the chemical composition limits. SAE (Society of Automotive Engineers) and AISI (American Iron and Steel Institute) use basically the same numbering system. The steels contain, in part, alloy additions of chromium, molybdenum, nickel, and vanadium. They are used widely in the automotive industry but have not been adopted for high temperature service. The purpose of this investigation was to study changes in microstructure observed in typical AISI constructional alloy steels in the welded and un-welded conditions after exposure for 34,000 hr at 900" and 1050" and, in several instances, 1200°F. The tensile and creep rupture properties after exposure for 10,000 hr were also evaluated. The investigation is a continuation of the work previously discussed. Little was known concerning the existence of graphite in medium or low carbon steels before 1943. It is important to note that continued exposure at elevated temperature is required in order to develop graphite in steels. Interest in the presence of graphite in steel, and also in changes in the properties of steels after long service at elevated temperatures, developed after 1943 when a failure of a welded joint of high temperature piping was associated with the graphitization of a relatively low carbon content steel with 0.50 pct Mo,8,0 Numerous investigations have beeen made in recent years studying the relationship of this type of failure to changes in properties. Attempts have been made to evaluate the performance of a number of steels, particularly in the heat-affected zone of welds. It was the unfortunate failure of a weld-heated zone in high temperature piping in the steam-power industry which focused attention upon possible failures, and upon the need for improved steels for high temperature piping service. Investigation by the National Tube Div., U. S. Steel Corp., Lorain Works, has included a wide variety of steels in an attempt to learn the effects of numerous factors and elements upon the long time performance of steels, although many of the compositions studied will never be used at elevated temperatures.1,4-7 Included were the well established AISI steel series, which offered opportunity to test moderately high carbon content steels as well as observe the effect of nickel, chromium, molybdenum, etc., upon the properties of these well known steels. The properties of the AISI steels were also studied for comparison with the previously reported properties of the Cr-Mo steels, now used by the steam-power industry.5,7 Materials and Testing Procedure The AISI alloy steels in Table I were exposed for 10,000 and 34,000 hr at 900°, 1050°, and 1200°F.

Jan 1, 1958

By A. William Johnson

It was pointed out in an earlier paper1 that our understanding of the atomic mechanism by which diffusion occurs in metallic alloys is scarcely in an advanced state. This unsatisfactory condition is the result not of any lack of interest, but of the difficulty of designing experiments that .will yield suitable data. The diffusion coefficient of an alloy, measured in the usual way, is simply a number specifying the rate of homogenization of a nonhomo-geneous metal; this number, of itself, can furnish neither the rate at which the individual atoms move nor information as to the mechanism by which they move. It does not necessarily follow, however, that such information cannot be obtained, even if the path to be followed is still not clear. Much success has been attained in the study of diffusion in ionic crystals. A number of experiments, for which there are few counterparts in connection with metals, yield information often indicating a detailed mechanism by which diffusion probably occurs. From such work, quite acceptable theories of lattice imperfections have been developed by Wagner, Schottky, Frenkel, Jost and others.2 It is postulated that real crystals of stoichiometric composition contain, in equilibrium, certain imperfections of which the most importarlt types are: (I) vacant cation sites, with an equal number of interstitial ions; (2) vacant anion sites, with an equal number of interstitial ions; (3) equal numbers of anions and cations in interstitial positions; (4) equal numbers of vacant anion and cation sites. The classification of a particular crystal according to this scheme then follows from studies of the variation of electrical conductivity with pressure of the electronegative component surrounding the crystal, with ion size, and with temperature; other physical phenomena, such as the Hall effect, have aided in establishing the classification. The relative mobility of the anion and cation may be determined by chemical analysis of the salt at the electrodes following electrolysis. With such information, and knowing that one ion never occupies the lattice site normally belonging to an ion of opposite sign, it is usually possible to ascertain the diffusion mechanism. It is clear that the same experiments are not applicable to metal crystals, and substitute experiments that yield as much information have not yet been devised. Much can be learned, however, about the mobilities of the two* kinds of atoms in alloys by the use of radioactive metals as indicators. Only one such experiment has been performed in the past. In 1933, Seith and Keil,3 in an effort to explain the great difference between the rate of diffusion of gold in lead and of lead in lead, measured the rate of diffusion of radioactive lead in 3 gold-lead

Jan 1, 1942

By Robert E. Cuthbertson

IT is the purpose of this paper to describe in detail the laboratory development and mill application of an unusual combination of flotation reagents employed in the concentrator of the Climax Molybdenum Co., on the Continental Divide, near Leadville, Lake County, Colorado. This development originated in an ore-dressing research laboratory maintained by Climax at the experimental plant of the Colorado School of Mines, which is staffed by men directly employed by the Climax Molybdenum Co. Mill-scale testing of laboratory developments was supervised by a representative from the testing laboratory, working in close cooperation with the operating staff at the mill. General milling practice at Climax is ably described in a paper by E. J. Duggan,1 mill superintendent. Other aspects of the Climax project have been described in papers by W. J. Coulter,2 by Butler, Vanderwilt and Henderson3 by Allen Kissock,4 and by Leo H. Glanville.5 Consequently, this paper will be confined to the metallurgical aspects of recent reagent developments, avoiding, as much as possible, repetition of material covered in these earlier publications. BRIEF HISTORY OF REAGENT PRACTICE AT CLIMAX Prior to the year 1937, the only reagents employed at Climax for froth production and collecting action in the flotation of molybdenite were steam-distilled or destructively distilled pine oils. The only exceptions to this practice were brief periods of mill testing, when reagents of various types were tried on an experimental basis. None of these experimental runs was sufficiently encouraging to justify its continuation as regular practice. Sodium, cyanide has been employed since the very early days of milling at Climax as an inhibiting agent for control of pyrite and chalcopyrite. Alkaline reagents such as lime or soda ash have been used in recent years to minimize the detrimental effect of iron salts on flotation of molybdenite. The presence of these harmful salts is attributed to the decomposition of fine metallics abraded from liners and balls in the first stage of regrinding rougher concentrate. Flint pebbles are used in subsequent regrinding, since alkaline reagents are not entirely adequate to offset the inhibiting effect of iron salts as the grind becomes progressively finer and the grade of concentrate progressively higher. Climax metallurgists were familiar at an early date with the use of petroleum products such as kerosene and gas oil as promoters of flotation of molybdenite. Charles C. Oliver6 discussed the use of pine oil and kerosene as early as 1920, in connection with the milling practice at Dominion Molybdenite Co., Quebec. Never theless, the early attempts to apply this knowledge in the Climax concentrator were complete failures. In the light of recent experience, it may seem strange that the early mill tests with petroleum

Jan 1, 1944

By George H. Cunningham, Allen C. Jephson

The plant for production of electrolytic zinc recently erected by the American Smelting and Rcfining Co. is situated along Nueces Bay, on the Gulf Coast, some 5 miles west by rail and highway from the city and port of Corpus Christi. A ship channel from the port now approaches to within 2 miles of the site. It is expected that this will be extended at some future date and so provide direct water shipment from the plant. In addition to Gulf shipping, an intercoastal waterway connects Corpus Christi with Houston and New Orleans. Factors leading to the establishment oi this plant in the area were: ample supplies of natural gas for the generation of electric power, advantageous shipping lanes, favorable market for acid, adequate supply of labor, and moderate climate. General Description The plant was erected primarily to assist with the production of high-grade zinc much needed for war purposes. Production started during October 1942. The purity of the slab-zinc output meets the American Society for Testing Materials' special high-grade spccifications. Other products of the plant are electrolytic cadmium and sulphuric acid. Residues containing lead, copper and silvcr are sent for treatment to the Company's smelter at El Paso, Texas. The design of the plant includes the use of Trail suspension roasting equipment, contact acid equipment, also batch leaching in mechanically agitated tanks, pressure filtering and washing of leach pulp, batch purification in mechanically agitated tanks followed by clarification in filter presses and cooling of purified solution by evaporation. Electrolysis is performed in cells using Tainton alloy anodes and aluminum cathodes. Cathode current density is 60 amp. per square foot. Except for the portion returned to the leaching division, the cell solution is continuously flowing in closed circuit through the cells to cooling towers, which hold cell temperatures within desired limits. Direct current for electrolysis, is supplied by generators driven by steam turbines. The cathode zinc is melted in a gas-fired furnace and cast in the usual way into slabs for shipment. The plant divides into five major divisions: Concentrates Storage, Roasting and Acid, Leaching, Electrolysis, Melting and Casting. No attempt is made to give many tabulated data in this paper; it is mainly a general description of the divisions and methods employed for operation. A plan is shown in Fig. I and a general flowsheet in Fig. 3. Concentrates Storage The original plan for inward shipments was to receive zinc concentrates by steamer at the port of Corpus Christi, there to unload into open railroad cars and move into the plant by rail. Up to the present, however, concentrates have been received mainly in box cars from mines in Mexico.

Jan 1, 1944

By E. J. Duggan

The mine and mill of the Climax Molybdenum Co. are at Climax, Colorado. Climax is on Fremont pass directly on the Continental Divide, at an elevation of 11,400 feet. Description of Ore The Climax ore-bearing rock is essentially an altered and highly silicified granite, fully half of the gangue being quartz. Molybdenite is the only mineral of economic consequence and most of it is intimately associated with quartz in the form of fine veinlets and stringers. Other minerals are molybdite, pyrite, and chal-copyrite. While the molybdite may be readily extracted by hydrometallurgical methods, its content is too low to make such operations profitable. The pyrite content ranges from 2 to 5 per cent and that of the chalcopyrite from 0.03 to 0.05 per cent. There is not enough copper to make its recovery attractive and one of the metallurgical problems is the elimination of it and the pyrite from the product. On account of the close association of the molybdenite with the quartz and the necessity of eliminating the pyrite and chalcopyrite from the final product, fine grinding followed by flotation is the only feasible method of concentration. History Construction of the first milling unit was started in 1917 and it was operated during parts of 1918 and 1919. In the postwar years, there was almost no demand for the product and production was at a standstill until 1924. The Company's research campaign to develop the use of the metal began to show results in that year. From r926 to 1932 production ranged from 500 to 1200 tons per day. In 1931 an additional mill section was built and production was gradually increased until in 1934 and 1935 about 3000 to 4000 tons was milled per day. This tonnage overtaxed the milling facilities, and as the demand for inolybdenum was growing constantly, additional milling equipment was needed. In 1936 and 1937 another crushing plant, six additional mill sections and the necessary auxiliary plants were constructed and brought into operation. This plant was designed to mill I0,000 tons per day, but it was not long before 12.500 tons was being treated during periods of peak demands. During the summer of 1941, to meet defense needs, the mill has been required to treat 15,500 tons per day. This has been accomplished with little plant expansion and at no loss in recovery, as will be described later. TO increase capacity still further, one more primary section is now being built. This will bring capacity to 18,000 tons per day, which can be stretched to 20,000 tons at a small sacrifice in recovery. Crushing There are two crushing plants: No. I, of 5000 tons capacity (flowsheet in Fig. I) and No. 2, of 15,000 tons capacity (Fig. a).

Jan 1, 1943

By George A. Morrison

THE Columbia Chemical Division of the Pittsburgh Plate Glass Co. is at Barberton, Ohio, 35 miles south of Cleveland. For many years large tonnages of limestone have been brought to the Barberton plant from distant points. The stone is here burnt in vertical kilns, the resultant product then hydrated and the hydrated lime used in chemical processing. To eliminate the expense of these shipments, the company decided to investigate a limestone bed known to exist on company property at Barberton, where the stone is used. The bed lay at a depth of more than 2000 ft. and was known locally as the "Deep Lime." Chemical analyses of sludge from churn-drill holes made some years ago proved that the limestone was of sufficient purity to warrant diamond-drill exploration. Four diamond-drill holes were put down at well-spaced intervals, to represent fairly an area of four miles by one mile. Cores logged as to chemical and physical conditions were found to compare closely, and to corroborate the earlier evidence that the limestone was of superior quality for chemical use. A plant of 300 tons per hour was subsequently decided upon. SITE The yard at the chemical plant was already so congested that location of the projected mine within its area could not be considered. Eventually a site was selected 2 miles northwest of the plant, near the main line of the Erie Railroad. Here 412 acres were owned outright by the company and stone rights were obtained on 250 additional acres. This location required a transportation line of nearly 2 miles (8800 ft.), crossing two major highways, and to avoid interruption of deliveries to the plant, overpasses were planned. GEOLOGY The limestone in the immediate vicinity lies about 2200 ft. below the surface. Geologists* identify this stone as Delaware of Devonian age. It is overlain by 18 ft. of unconsolidated (sand and gravel), 100 ft. of water-bearing sandstone, and finally 2080 ft. of shale into which sandstone in thin layers is interbedded. The contact of shale and limestone is abrupt, flat-lying and very pronounced. Berea sandstone, often found at 520 ft., is absent, but Euclid sandstone was encountered, together with a seepage of oil and a small amount of methane gas. The limestone bed itself is 345 ft. thick, and overlies 200 ft. of gypsum. The lower part becomes dolomitic as it approaches the gypsum. A detailed study of the drill cores indicates that the upper 50 ft, are highest in lime and reasonably low in silica. The physical make-up shows several separating cherty layers. These occur at definite horizons and cause distinct partings, which become horizontal planes of

Jan 1, 1943

By John L. Lamont, Walter Crafts

STUDIES of the effect of composition of steel on hardenability by Grossmann,1 and as-quenched hardness by Field2 and by the authors,3 have made it possible to predict the results of quenching when the composition and cooling rate are known. In order to extend the application of the hardenability calculation to the quenched and tempered condition in which steel is finally used, a survey has been made of the hardness changes caused by tempering. From this study a method has been developed for the prediction of hardness and tensile strength of steel in the tempered condition. The method of calculation was developed from Rockwell C hardness tests on quenched and tempered Jominy specimens and is expressed in Rockwell C hardness units. It is of an additive type in which the degree of softening from as-quenched hardness is estimated. Tempered properties may be calculated within about plus or minus 5 Rockwell C hardness or plus or minus 15,000 lb. per sq. in. tensile strength. This degree of accuracy is less than that necessary for the control of heat-treatment, but is adequate for the comparative evaluation and selection of alloy steels. The formula indicates that tempered hardness is primarily dependent on as- quenched hardness and, as in the hardening reaction, the progress of tempering is controlled mainly by the carbon content- Alloys tend to retard softening by a secondary hardening mechanism in which the alloy appears to migrate from ferrite to the carbide phase. The factors for the effects of alloys in tempering vary so much from the effects of alloys in hardening that different steels of equivalent hardenability may, after lie heat-treatment, differ considerably in tensile strength. PROCEDURE In developing the method for calculating tempered Rockwell C hardness, simple and complex steels were tested over a range from 0.08-to 0.65 per cent carbon and up to 2.68 per cent manganese, 2.18 silicon, 3.50 chromium, 4.94 nickel, and 1.06 molybdenum. The steels were made as small induction-furnace heats at the Union Carbide and Carbon Research Laboratories, Inc. The accuracy of the method was finally checked on a variety of carbon, low-alloy and high- alloy types of heat-treating steels produced under commercial conditions. The method was based on a study of tempered Jominy bars, and its validity was tested by correlation with the center hardness and tensile strength of oil-quenched and tempered bars from ¼ to 4 in. in diameter. The method of calculation was derived from the differences in Rockwell C hardness between as-quenched and quenched and tempered Jominy specimens. Prenormalized Jominy hardenability specimens quenched from a normal temperature for austenitization were used to obtain a range of as-quenched Rockwell C

Jan 1, 1946

By Robert E. Cuthbertson

It is the purpose of this paper to describe in detail the laboratory development and mill application of an unusual combination of flotation reagents employed in the concentrator of the Climax Molybdenum Co., on the Continental Divide, near Leadville, Lake County, Colorado. This development originated in an ore-dressing research laboratory maintained by Climax at the experimental plant of the Colorado School of Mines, which is staffed by men directly employed by the Climax Molybdenum Co. Mill-scale testing of laboratory developments was supervised by a representative from the testing laboratory, working in close cooperation with the operating staff at the mill. General milling practice at Climax is ably described in a paper by E. J. Duggan,1 mill superintendent. Other aspects of the Climax project have been described in papers by W. J. Coulter,2 by Butler, Vanderwilt and Henderson,= by Allen Kissock,4 and by Leo H. Glanville.5 Consequently, this paper will be corfined to the metallurgical aspects of recent reagent developments, avoiding, as much as possible, repetition of material covered in these earlier publications. Brief History of Reagent Practice at Climax Prior to the year 1937, the only reagents employed at Climax for froth production and collecting action in the flotation of molybdenite were steam-distilled or destructively distilled pine oils. The only exceptions to this practice were brief periods of mill testing, when reagents of various types were tried on an experimental basis. None of these experimental runs was sufficiently encouraging to justify its continuation as regular practice. Sodium cyanide has been employed since the very early days of milling at Climax as an inhibiting agent for control of pyrite and chalcopyrite. Alkaline reagents such as lime or soda ash have been used in recent years to minimize the detrimental effect of iron salts on flotation of molybdenite. The presence of these harmful salts is attributed to the decomposition of fine metallics abraded from liners and balls in the first stage of regrinding rougher concentrate. Flint pebbles are used in subsequent regrinding, since alkaline reagents are not entirely adequate to offset the inhibiting effect of iron salts as the grind becomes progressively finer and the grade of concentrate progressively higher. Climax metallurgists were familiar at an early date with the use of petroleum products such as kerosene and gas oil as promoters of flotation of molybdenite. Charles C. Oliver6 discussed the use of pine oil and kerosene as early as 19-20, in connection with the milling practice at Dominion Molybdenite Co., Quebec. Nevertheless, the early attempts to apply this knowledge in the Climax concentrator were complete failures. In the light of recent experience, it may seem strange that the early mill tests with petroleum

Jan 1, 1947

By George A. Morrison

The Columbia Chemical Division of the Pittsburgh Plate Glass Co. is at Bar-berton, Ohio, 35 miles south of Cleveland. For many years large tonnages of limestone have been brought to the Barberton plant from distant points. The stone is here burnt in vertical kilns, the resultant product then hydrated and the hydrated lime used in chemical processing. To eliminate the expense of these shipments, the company decided to investigate a limestone bed known to exist on company property at Barberton, where the stone is used. The bed lay at a depth of more than 2000 ft. and was known locally as the "Deep Lime." Chemical analyses of sludge from churn-drill holes made some years ago proved that the limestone was of sufficient purity to warrant diamond-drill exploration. Four diamond-drill holes were put down at well-spaced intervals, to represent fairly an area of four miles by one mile. Cores logged as to chemical and physical conditions were found to compare closely, and to corroborate the earlier evidence that the limestone was of superior quality for chemical use. A plant of 300 tons per hour was subsequently decided upon. SITe The yard at the chemical plant was already so congested that location of the projected mine within its area could not be considered. Eventually a site was selected 2 miles northwest of the plant, near the main line of the Erie Railroad. Here 412 acres were owned outright by the company and stone rights were obtained on 2 50 additional acres. This location required a transportation line of nearly 2 miles (8800 ft.), crossing two major highways, and to avoid interruption of deliveries to the plant, overpasses were planned. Geology The limestone in the immediate vicinity lies about 2200 ft. below the surface. Geologists* identify this stone as Delaware of Devonian age. It is overlain by 18 ft. of unconsolidated (sand and gravel), 100 ft. of water-bearing sandstone, and finally 2080 ft. of shale into which sandstone in thin layers is interbedded. The contact of shale and limestone is abrupt, flat-lying and very pronounced. Berea sandstone, often found at 520 ft., is absent, but Euclid sandstone was encountered, together with a seepage of oil and a small amount of methane gas. The limestone bed itself is 345 ft. thick, and overlies 200 ft. of gypsum. The lower part becomes dolomitic as it approaches the gypsum. A detailed study of the drill cores indicates that the upper 50 ft. are highest in lime and reasonably low in silica. The physical make-up shows several separating cherty layers. These occur at definite horizons and cause distinct partings, which become horizontal planes of

Jan 1, 1946

By Robert E. Cuthbertson

It is the purpose of this paper to describe in detail the laboratory development and mill application of an unusual combination of flotation reagents employed in the concentrator of the Climax Molybdenum Co., on the Continental Divide, near Leadville, Lake County, Colorado. This development originated in an ore-dressing research laboratory maintained by Climax at the experimental plant of the Colorado School of Mines, which is staffed by men directly employed by the Climax Molybdenum Co. Mill-scale testing of laboratory developments was supervised by a representative from the testing laboratory, working in close cooperation with the operating staff at the mill. General milling practice at Climax is ably described in a paper by E. J. Duggan,1 mill superintendent. Other aspects of the Climax project have been described in papers by W. J. Coulter,2 by Butler, Vanderwilt and Henderson,= by Allen Kissock,4 and by Leo H. Glanville.5 Consequently, this paper will be corfined to the metallurgical aspects of recent reagent developments, avoiding, as much as possible, repetition of material covered in these earlier publications. Brief History of Reagent Practice at Climax Prior to the year 1937, the only reagents employed at Climax for froth production and collecting action in the flotation of molybdenite were steam-distilled or destructively distilled pine oils. The only exceptions to this practice were brief periods of mill testing, when reagents of various types were tried on an experimental basis. None of these experimental runs was sufficiently encouraging to justify its continuation as regular practice. Sodium cyanide has been employed since the very early days of milling at Climax as an inhibiting agent for control of pyrite and chalcopyrite. Alkaline reagents such as lime or soda ash have been used in recent years to minimize the detrimental effect of iron salts on flotation of molybdenite. The presence of these harmful salts is attributed to the decomposition of fine metallics abraded from liners and balls in the first stage of regrinding rougher concentrate. Flint pebbles are used in subsequent regrinding, since alkaline reagents are not entirely adequate to offset the inhibiting effect of iron salts as the grind becomes progressively finer and the grade of concentrate progressively higher. Climax metallurgists were familiar at an early date with the use of petroleum products such as kerosene and gas oil as promoters of flotation of molybdenite. Charles C. Oliver6 discussed the use of pine oil and kerosene as early as 19-20, in connection with the milling practice at Dominion Molybdenite Co., Quebec. Nevertheless, the early attempts to apply this knowledge in the Climax concentrator were complete failures. In the light of recent experience, it may seem strange that the early mill tests with petroleum

Jan 1, 1947

By J. L. Lamont, W. Crafts

Studies of the effect of composition of steel on hardenability by Grossmann,' and as-quenched hardness by Field2 and by the authors, have made it possible to predict the results of quenching when the composition and cooling rate are known In order to extend the application of the hardenability calculation to the quenched and tempered condition in which steel is finally used, a survey has been made of the hardness changes caused by tempering. From this study a method has been developed for the prediction of hardness and tensile strength of steel in the tempered condition. The method of calculation was developed from Rockwell C hardness tests on quenched and tempered Jominy specimens and is expressed in Rockwell C hardness units. It is of an additive type in which the degree of softening from as-quenched hardness is estimated. Tem-pred properties may be calculated within about plus or minus 5 Rockwell C hardness or plus or minus 15,000 lb. per sq, in. tensile strength. This degree of accuracy is less than that necessary for the control of heat-treatment, but is adequate for the comparative evaluation and selection of alloy steels. The formula indicates that tempered hardness is primarily dependent on as-quenched hardness and, as in the hardening reaction, the progress of tempering is controlled mainly by the carbon content. Alloys tend to retard softening by a secondary hardening mechanism in which the alloy appears to migrate from ferrite to the carbide phase. The factors for the effects of alloys in tempering vary so much from the effects of alloys in hardening that different steels of equivalent hardenability may, after like heat-treatment, differ considerably in tensile strength. Procedure In developing the method for calculating tempered Rockwell C hardness, simple and complex steels were tested over a range from 0.08 to 0'65 per cent carbon and up to 2.68 per cent manganese, 2.18 silicon, 3.50 chromium, 4.94 nickel, and 1.06 molybdenum. The steels were made as small induction-furnace heats at the Union Carbide and Carbon Research Laboratories, Inc' The accuracy of the method was finally checked on a variety of carbon, low-alloy and high-alloy types of heat-treating steels produced under commercial conditions. The method was based on a study of tempered Jominy bars, and its validity was tested by correlation with the center hardness and tensile strength of oil-quenched and tempered bars from 1/2 to 4 in. in diameter. The method of calculation was derived from the differences in Rockwell C hardness between as-quenched and quenched and tempered Jominy specimens. Prenormalized Jominy hardenability speci-menS quenched from a normal temperature for austenitizatios were used to obtain a range of as-quenched Rockwell C

Jan 1, 1948

By W. Crafts, J. L. Lamont

Studies of the effect of composition of steel on hardenability by Grossmann,' and as-quenched hardness by Field2 and by the authors, have made it possible to predict the results of quenching when the composition and cooling rate are known In order to extend the application of the hardenability calculation to the quenched and tempered condition in which steel is finally used, a survey has been made of the hardness changes caused by tempering. From this study a method has been developed for the prediction of hardness and tensile strength of steel in the tempered condition. The method of calculation was developed from Rockwell C hardness tests on quenched and tempered Jominy specimens and is expressed in Rockwell C hardness units. It is of an additive type in which the degree of softening from as-quenched hardness is estimated. Tem-pred properties may be calculated within about plus or minus 5 Rockwell C hardness or plus or minus 15,000 lb. per sq, in. tensile strength. This degree of accuracy is less than that necessary for the control of heat-treatment, but is adequate for the comparative evaluation and selection of alloy steels. The formula indicates that tempered hardness is primarily dependent on as-quenched hardness and, as in the hardening reaction, the progress of tempering is controlled mainly by the carbon content. Alloys tend to retard softening by a secondary hardening mechanism in which the alloy appears to migrate from ferrite to the carbide phase. The factors for the effects of alloys in tempering vary so much from the effects of alloys in hardening that different steels of equivalent hardenability may, after like heat-treatment, differ considerably in tensile strength. Procedure In developing the method for calculating tempered Rockwell C hardness, simple and complex steels were tested over a range from 0.08 to 0'65 per cent carbon and up to 2.68 per cent manganese, 2.18 silicon, 3.50 chromium, 4.94 nickel, and 1.06 molybdenum. The steels were made as small induction-furnace heats at the Union Carbide and Carbon Research Laboratories, Inc' The accuracy of the method was finally checked on a variety of carbon, low-alloy and high-alloy types of heat-treating steels produced under commercial conditions. The method was based on a study of tempered Jominy bars, and its validity was tested by correlation with the center hardness and tensile strength of oil-quenched and tempered bars from 1/2 to 4 in. in diameter. The method of calculation was derived from the differences in Rockwell C hardness between as-quenched and quenched and tempered Jominy specimens. Prenormalized Jominy hardenability speci-menS quenched from a normal temperature for austenitizatios were used to obtain a range of as-quenched Rockwell C

Jan 1, 1948

By J. G. Morlet, A. R. Troiano, H. H. Johnson

Delayed failure in steel occurs by controlled initiation and growth of a crack. The incubation period for crack initiation was measured. Crack initiation and Propagation are controlled by interaction between hydrogen concentration and triaxial stress state. The incubation period results from stress-induced diffusion of hydrogen to the point of crack initiation. THIS paper describes the phenomenon of delayed failureland the kinetics of crack initiation and propagation in uniformly hydrogenated steel. The investigation was prompted by service failures of high-strength-steel components at applied stresses far below the conventional yield strength, after the part had successfully sustained equal or higher stresses for an extended time interval. This delayed failure phenomenon, often termed static fatigue, is associated1 with the presence of hydrogen. This is not surprising, since the voluminous literature on flaking and hydrogen embrit-tlement demonstrates that hydrogen may exert a potent embrittling influence. Flakes, or internal hairline cracks in alloy-steel forgings, are related to the presence of hydrogen retained from the steel-making process.2 On the other hand, embrit-tlement arises from hydrogen introduced during surface treatments such as acid pickling or electroplating. Laboratory delayed failures have been induced in notch specimens of 4340 steel by electrolytic charging of the specimen surface with hydrogen and subsequent static stressing.l,4,5 Static fatigue was observed over a wide range of applied stresses; however, failure did not occur below a critical applied stress, designated as the static fatigue limit. In this instance the extended time for failure resulted primarily from the macroscopic redistribution of hydrogen. A crack formed to the depth of the hydrogen enriched "case* upon loading; further crack growth naturally awaited diffusion of hydrogen into the material ahead of the crack. The crack-propagation rate was therefore controlled primarily by the macroscopic diffusion of hydrogen into the specimen interior during the test. Thus, in this instance static fatigue was associated with the movement of a gross concentration gradient. However, delayed failure in steel of uniform hydrogen concentration is of greater fundamental interest, as well as commercial significance. With a homogeneous hydrogen distribution a different mode of delayed failure might be expected. As the heterogeneous hydrogen distribution became more uniform,4,5 the initial crack-propagation rate decreased markedly and, in fact, what appeared to be an incubation period for crack initiation was observed. However, the macroscopic concentration gradient precluded an accurate evaluation of these observations. Although the existence of an incubation period, up to this time, has not been established definitely, it is not amiss to point out some implications of the concept. It is of interest in all hydrogen-induced embrittlement phenomena, such as flaking, delayed failure, and hydrogen embrittlement. Much discussion has centered around the possibility of an

Jan 1, 1959

By Stanley D. Michaelson, Norman Weisis

The purpose of beneficiation is to increase the economic value of an ore by elimination of waste rock or by separation of minerals that require separate reduction, without destroying the physical and chemical identity of the minerals. Flotation has replaced older methods of beneficiation to a very great ex- tent, nearly entirely in the case of the copper, lead, and zinc minerals and less completely in the case of such other minerals as iron, coal, and titanium. Flotation is also used to recover barite, fluorspar, feldspar, cement rock, spodumene, vermiculite, silica, beryl, and potash in the nonmetallic field, and cobalt, vanadium, germanium, antimony, mercury, molybdenum, manganese, nickel, gold and silver, cadmium, and bismuth for metals. The rapid growth of flotation to pre-eminence cannot be attributed to its low cost, because gravity, magnetic, and electrical methods may in some cases cost only half as much. But for ores containing finely disseminated minerals, these other methods are successful only in exceptional cases, for example the magnetic taconites or titanium-bearing sands. For low grade ores with coarse texture or spotty mineralization the advantages of low-cost gravity methods and highly efficient flotation are often combined, as in the beneficiation of coal and some ores of lead and zinc, phosphate, tungsten, and manganese. When an ore is responsive to either flotation or non-flotation concentration, or to combinations of the two, the choice depends upon cost of the process only when dealing with ores of low value; in other cases it is dictated by either the process efficiency or the product specification. Generally speaking, flotatio.1 is so efficient as compared with other methods of concentration that process cost is rarely an important factor in its selection. It is said, "The metal in the mill tailing has already been mined." Once the mining cost has been paid it doesn't increase total costs very much to do a thorough job of milling. With the exception of the few types of ores that are not amenable to flotation, the chief reason for preferring electrical and gravity methods to flotation may lie in the specification of the product. Flotation demands fine grinding, and specifications may not permit this with many nonmetallic ores or coal. Another reason is the size of investment-where capital is hard to obtain or the life of the property is short, the justification for a flotation plant may not exist, and one must be content to skim off the cream. y not exist, and one must be content to skim off the cream. Gravity processes often cost less than flotation because a large part of the waste rockcan be rejected without costly grinding, no chemicals are required,

Jan 1, 1962

By E. P. Polushkin, Henry L. Shuldener

This paper describes the results of microscopic examination of a series of brass pipes removed from apartment and office buildings in New York City, adjacent localities on Long Island, and Philadelphia. They were selected as typical of approximately four hundred pipe specimens obtained over a period of five years during an investigation of corrosion in hot-water installations. A part of the investigation is reported in this paper and includes a brief history of the pipes, a description of their inside surface and microstructure, and a study of the effects of corrosion, with particular reference to the structural aspects of local and selective dezincification. Although the bibliography on the corrosion of brass pipes is quite extensive, it refers almost entirely to corrosion in sea water. The authors believe that their examination of this series of pipes, which had been subjected to the corrosive action of fresh water for various lengths of time, may throw some additional light on the problem of corrosion. Pipes Examined The pipes were made by different manufacturers and their sizes range from 3/4 in. to 4 in. nominal inside diameter, the majority being within I to 2 in. They can be divided into two groups according to chemical composition: (I) with a copper content of 60 to 62 per cent and (2) with a copper content of 65 to 68 per cent. The first group (pipes made of Muntz metal) comprises 22 pipes and the second (pipes made of high brass) comprises 18 pipes. The pipes had been in service in various locations in the hot-water systems of the buildings involved. Some were taken from horizontal lines in the basement, some from overhead distributors and some from vertical risers. The distance, in terms of feet of pipe, of the specimens from the hot-water generator was no less than 75 ft. and often IOO to 300 ft. In the majority of cases the water-heating equipment was provided with a regulator to limit the temperature of the hot water supply. The normal range of temperature in pipe systems of this kind is Ioo° to 160°F. Water Supples The average chemical composition of the water supplies carried by the pipes is shown in Table I. In evaluating the corrosiveness of a natural water, four factors are considered of prime importance: namely, hardness, alkalinity, pH and silica content. The waters listed in Table 1 are characterized by relatively low hardness, 10, alkalinity, low pH and low silica content. The waters of lower pH and higher CO2 content are more corrosive. A characteristic of all of these waters is that they do not deposit a protective mineral coating as do waters with high bicarbonate of lime content, which would be reflected

Jan 1, 1945

By F. R. Hensel

PuRe silver and silver-lead alloys have been studied as to their suitability for bearing~.' A review of the properties of thallium and the silver-thallium constitutional diagram was made by the author to analyze the possibilities of silver-thallium compositions for antifriction materia1s. t The silver-rich end of the diagram as reported in the literatureg-" was found to be sketchy and it was necessary to carry out corisiderable experimental work to arrive at definite conclusions. Some of the results of this work are reported in this paper. Test Materials In the beginning of the work, only fused alloys were investigated. Later, research Table i.—Composition of Fused Silver-thallium Alloys Tested for Antifriction Properties Percentage Alloy No. of Thallium 1533...................... 0.48 1534.................... 1.06 a31 HT................... 2.04 231....................... 2.10 232 HT................... 3.83 Balance 232....................... 4.07 Silver 233 HT................... 5.86 a33....................... 6.38 a34....................... 9.84 a34 HT................... 10.07 was carried out on electroplating methods and diffusion processes. In preparing the fused alloyst care was taken to exhaust the toxic fumes caused by the thaillium content. The compositions of the series of fused alloys are listed in Table I. The silver-thallium alloys were melted in clay-graphite crucibles and cast into preheated steel molds of 3/4-in, diameter. In the cast condition, they showed a cored structure, as indicated by the micrographs of Figs. I to 3. The etching reagent used was a mixture of 2 grams K2Cr207, 8 C.C. H2S04, and IOO C.C. H20. The cored structure is unsatisfactory for the type of corrosion resistance required for bearing applications, and homogenizing experiments were carried out at various temperatures, the results of which are shown in Figs. 4 through 8. The alloys with a lower thallium concentration, which were heated for 2 hr. at 525°C show an almost completely homogenized solid solution type of structure. With higher thallium concentration, the homogenizing temperature was dropped to 475OC. to eliminate the formation of a liquid phase. It is evident that heating for 2 hr. at this temperature did not iesiilt iii complete elimination of the cored structure. As would be expected, cold-working of the cast structure is an expedient in establishing equilibrium conditions. The fine homogeneous grain structure shown in Fig. 7 corresponds to the cold-worked area under the Rockwell ball penetration when the hardness was taken before heat-treatment. A detailed structural study was made on a cast silver-thallium alloy containing 3.67 per cent thallium. Three micrographs (Figs. 9, 10 and 11) show the transition

Jan 1, 1946

By F. R. Hensel

PuRe silver and silver-lead alloys have been studied as to their suitability for bearing~.' A review of the properties of thallium and the silver-thallium constitutional diagram was made by the author to analyze the possibilities of silver-thallium compositions for antifriction materia1s. t The silver-rich end of the diagram as reported in the literatureg-" was found to be sketchy and it was necessary to carry out corisiderable experimental work to arrive at definite conclusions. Some of the results of this work are reported in this paper. Test Materials In the beginning of the work, only fused alloys were investigated. Later, research Table i.—Composition of Fused Silver-thallium Alloys Tested for Antifriction Properties Percentage Alloy No. of Thallium 1533...................... 0.48 1534.................... 1.06 a31 HT................... 2.04 231....................... 2.10 232 HT................... 3.83 Balance 232....................... 4.07 Silver 233 HT................... 5.86 a33....................... 6.38 a34....................... 9.84 a34 HT................... 10.07 was carried out on electroplating methods and diffusion processes. In preparing the fused alloyst care was taken to exhaust the toxic fumes caused by the thaillium content. The compositions of the series of fused alloys are listed in Table I. The silver-thallium alloys were melted in clay-graphite crucibles and cast into preheated steel molds of 3/4-in, diameter. In the cast condition, they showed a cored structure, as indicated by the micrographs of Figs. I to 3. The etching reagent used was a mixture of 2 grams K2Cr207, 8 C.C. H2S04, and IOO C.C. H20. The cored structure is unsatisfactory for the type of corrosion resistance required for bearing applications, and homogenizing experiments were carried out at various temperatures, the results of which are shown in Figs. 4 through 8. The alloys with a lower thallium concentration, which were heated for 2 hr. at 525°C show an almost completely homogenized solid solution type of structure. With higher thallium concentration, the homogenizing temperature was dropped to 475OC. to eliminate the formation of a liquid phase. It is evident that heating for 2 hr. at this temperature did not iesiilt iii complete elimination of the cored structure. As would be expected, cold-working of the cast structure is an expedient in establishing equilibrium conditions. The fine homogeneous grain structure shown in Fig. 7 corresponds to the cold-worked area under the Rockwell ball penetration when the hardness was taken before heat-treatment. A detailed structural study was made on a cast silver-thallium alloy containing 3.67 per cent thallium. Three micrographs (Figs. 9, 10 and 11) show the transition

Jan 1, 1946

By B. B. Zavoico

During 1936 the Russian oil industry made very satisfactory progress and, while not all difficulties of organization have been ironed out, the country is now assured of a supply of petroleum products in sufficient quantities and of quality demanded by modern motor equipment. The year 1937 promises to better by a wide margin the good showing of 1936. The statistics given in this paper for the first time take into consideration the varying gravities of crude oils of the several Russian oil fields instead of using a flat conversion factor of 7 bbl. per metric ton. It was found from the detailed study that the generally used average conversion factor should be increased from 7 to 7.25 bbl. per metric ton, the figure varying, of course, with the gravity of oil in the individual fields. Crude-oil production during 1936 is estimated at 201,500,000 bbl. as compared with 182,970,000 bbl. produced in 1935, an increase of 9.4 per cent. The greatest increase was again recorded in the Baku district, which increased its production by 10.9 per cent, from 141,257,000 bbl. in 1935 to 158,300,000 in 1936. Grozny district maintained its production at a level of about 23,000,000 bbl., but its old fields continued to decline and production was sustained by the development of newer fields. A great advance was made in drilling speeds and the total footage in 1936 reached 6,694,200 ft. as compared with 4,926,600 ft. drilled in 1935, an increase of 26.4 per cent. In older deep fields, producers were being completed at over 8000 ft.—a great depth for Russian drillers but two years ago. Several major discoveries were made in 1936. Northeast Caucasus.—Izberbash, east from Grozny and on the Caspian Sea, was the outstanding discovery, the initial production of the discovery well being around 3000 bbl. per day from about 5000 ft. The importance of the field is due to the large area of the structure, half of which, however, is under the sea, and also to its strategic location on the shores of the Caspian and near a trunk pipe line to the Grozny refining center. An active development program is being pursued in Izberbash and its 1937 production quota is set at 7,500,000 bbl. Achi-Su field, near Izberbash, also discovered during 1936, while not as prolific as Izberbash, is thought to cover a very large area and the small

Jan 1, 1937