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By S. Shapiro, G. Krauss

RECENT investigations1 3 of the products of marten-sitic transformation in Fe-Ni and Fe-Ni-C alloys have made use of light microscopy to describe mar-tensitic fine structure. The application of conventional metallographic techniques to this problem was possible because of the similarity of distributions of parallel striations developed by etching polished surfaces to distributions of transformation twins which are positively identified in thin films by transmission electron microscopy. The surface striations frequently are not well-defined, and could also be due to, for example, rows of etch pits which are not resolved by the light microscope. This note describes the etching effects revealed by examination of surface replicas of mar-tensite in the electron microscope. The application of a replica technique both extends the observations of fine structure made with the light microscope and allows the results of conventional metallography to be used with more confidence. Samples of an Fe-33 wt pct Ni alloy were used for this study because of the detailed knowledge of the fine structure of martensite which has been developed'-4 for alloys of about this composition. Samples transformed to martensite at -120°C, and transformed samples heated to 340°C to effect a small amount of reversal of martensite to austenite, were examined. Surfaces were first prepared for replication by elec-tropolishing in a chromium oxide-acetic acid electrolyte at a current density of 0.1 amp per sq cm and a temperature of 15°C or a perchloric acid-acetic acid electrolyte at a current density of approximately 2 amps per sq cm and a temperature of 15°C. The polished surfaces were then etched for 4 to 7 sec by immersion in a solution of equal parts HC1, HNO,, and H20. Application of the etchant for this period of time produced discrete attack of certain features without loss of resolution due to overlapping of areas most susceptible to etching. The etched surfaces were replicated by 1) preshadowing with Pt-Pd alloy at an angle of 20 to 30 deg, 2) depositing a thin carbon film, and 3) stripping the film and shadowing material by immersion in a 5 pct nital solution. Two types of etching effects were observed by examination of the surface replicas in the electron microscope: l) continuous striations centered at the bottom of long grooves or the tops of pyramidal elevations on the sample surface, and 2) high densities of fine etch pits. Examples of both types of features are shown in Figs. 1 to 4. The striations are in each case continuous and have the same characteristic configurations as do transformation twins in martensite. Fig. 1 shows that the density of grooves decreases toward the edge of a martensite plate and Fig. 2 shows a region where the striations are of varying length. Similar examples of transformation twin arrangements determined by transmission electron microscopy of thinned foils of martensite have been shown in the literature,'~ and, based on these similarities, the striations and their associated grooves or mounds are considered to be evidence for the presence of transformation twins. The transf~rmation twins in martensite are on the order of l00 A thick, much too fine for resolution by the light microscope. It appears that orientation-dependent etching of the matrix martensite about the twins results in grooves or surface elevations which

Jan 1, 1967

By Robert B. Hall, Charles W. Bauer

Alunite, KA13(SO4)2(OH)6, was used from the 15th century until early in the present century as a source of potash alum and aluminum sulfate. Since early in this century its use for this purpose has declined to virtually nil with acid treatment of bauxite or clay replacing alunite as a source of alum. During the First World War alunite served as an emergency source of potassium sulfate fertilizer in the United States and Australia. More recently, alunite has been investigated as a nonbauxite ore of aluminum, with potassium sulfate and sulfuric acid as recoverable byproducts. The Soviet Union established a commercial-scale plant in the mid-1960s producing cell-grade alumina from alunitic ore and recovering byproduct potassium sulfate and sulfuric acid. Interest in nonbauxite ores, including alunite, is expected to continue in countries that presently are dependent on imports of bauxite or alumina to support their aluminum industries. The US has the largest aluminum producing and fabricating industry in the world but imports more than 90% of its aluminum-bearing raw materials. This chapter reviews the status of alunite as a potential source of aluminum with byproduct fertilizer, and the resources available to support this industry, whenever this becomes economically feasible. Historical Background Alunite has received little attention until recently, yet for centuries it held a higher place than many of the industrial minerals considered essential today. The deposits of alunite at Tolfa, northwest of Rome, were mined almost continuously from 1462 until about the middle of the present century (DeLaunay, 1907; Lombardi, 1977). The potash alum made from the alunite, called Roman alum, was a valued commodity in international trade, being used in the making of paper, in tanning leather, and as a mordant in textile dyeing. The industry at Tolfa is said to have been controlled by the Vatican and was a source of revenue for the Papal State until fairly recent times (Lombardi et al., 1977). Since early in the present century, the preferred method for making alum has been by acid treatment of bauxite, clay, or other aluminous material, so that alunite has fallen into near-total disuse as a source of alum chemicals. Appreciable quantities of mixed alunite-kaolin rock still are quarried in the Tolfa district for use by the Italian cement industry (Lombardi and Mattias, 1979), but the role of this material in the making of Italian cement is not clear. A large deposit of alunite-bearing rock in Chekiang province, mainland China, is said to have yielded a "great quantity" of alum over a period of several centuries (Yih, 1931). During the 19th century, alunite deposits in France, Spain, Australia, and other countries were exploited as raw material for making potash alum and aluminum sulfate. Interest in alunite was revived during the First World War, not for alum, but as an emergency source of potassium sulfate fertilizer. Large veins of nearly pure alunite had just been discovered on Alunite Ridge, 11 km southwest of Marysvale in Piute County, Utah (Butler and Gale, 1912), and these were quickly brought into production for making potash fertilizer to replace supplies cut off from the famous deposits at Stassfurt, Germany. An estimated 225 kt of Marysvale alunite was mined and processed at that time (Callaghan, 1973). Similarly, Australian alunite deposits were mined as a source of potash fertilizer during both world wars (Hall, 1978).

Jan 1, 1983

By S. R. Balajee, I. Iwasaki

The adsorption mechanism of corn starch and its derivatives at mineral-solution interfaces was investigated by the adsorption of cationic starch, unmodified corn starch, British Gum 9084, and anionic starch on quartz and hematite. The adsorption of these starches, which decreases in the order mentioned, is dependent on the balance between the magnitude of the electrostatic interaction and the magnitude of the hydrogen bonding. There exists a critical starch concentration for both optimum flotation and flocculation conditions of iron ores, which corresponds to a point where the starch adsorption reaches a saturation coverage. Flocculation occurs due to the adsorption of starch via electrostatic and hydrogen-bonding forces and by interparticle bridging as a result of the conformation of starch molecules at the interface. The depressant property of starches and starch derivatives in flotation' and their flocculation char: acteristics in clarification and filtration2.3 have long been recognized on a wide variety of ores. The effectiveness of a starch as a depressant for iron minerals has been the subject of much investigation in recent years both in the amine flotation of siliceous gangue and in the anionic flotation of activated silica from iron ores. It has been reported that the depressant activity of starches and dextrins in the cationic flotation of quartz from hematite increases with molecular weight, branching, and number of hydroxyl groups, 1 and that the selectivity is affected by changing the configuration of starch molecules and the composition of its polar groups.4 ,5 The manner in which starches are solubilized was shown to exert a significant influence as a depressant in the anionic silica flotation, and a series of articles covering the practical aspects of flotation and flocculation have already been reported.618 Chemical modification of the starch structure, the pulp pH, the calcium ion, and the residual starch concentration were identified as some of the more important variables affecting the flotation behavior. In the flocculation of iron ores, it was noted that most starches flocculated suspensions of hematite in water but did not flocculate similar suspensions of quartz,9 and that an excessive use of starch restabilized the suspensions due presumably to protective action. 6 An admirable application of such an observation to practice may be cited in the selective flocculation and desliming in the anionic silica flotation of iron ores, which resulted in superior metallurgy and lower reagent cost. 10 From detailed adsorption measurements, Schulz'and Cooke4 established that the adsorption of starches and their derivatives depended on the types of minerals and of starches, pH, and electrolytes present. Their adsorption data and the foregoing flotation and flocculation observations suggested that an electrical interaction between starches and charged mineral surfaces might be playing a role in their adsorption process. Adsorption of organic polymers, particularly of synthetic origin, at solid-liquid interfaces has been extensively studied in recent years,' and it is realized that their adsorption mechanism is considerably more complex than that of simple ions or molecules. A polymer molecule possesses a number of functional groups, and the adsorption at a point may restrict the adsorbability of adjacent groups. The mechanism may be further complicated by the conformation of the polymer molecules which may exist as coiled spheres, helices, or extended chains as a result of intramolecular interactions among functional groups as well as intermolecular interactions with solvent molecules. The object of the present investigation was to examine the effect of the chemical modification on the adsorption characteristics of starches and starch products on quartz and hematite at several pH values, so that by correlating this information with flocculation and flotation results, adsorption mechanism of starches on mineral-solution interface may be elucidated. EXPERIMENTAL MATERIALS Quartz: St. Peter sand was screened at 35 mesh and the undersize was scrubbed and deslimed at a Fagergren cell. The deslimed sand was cleaned with 0.1 N hot hydrochloric acid and washed repeatedly with distilled water, For anuscript, measurementsl the -200-mesh fraction of the sand was ground dry in a porcelain mill for 3 hr. The specific surface of the finely ground quartz was

Jan 1, 1970

By G. T. Smith, R. C. Moyer

Cadmium, along with other impurities such as lead, gallium, germanium and indium, is characteristically found associated with zinc ores, the average ratio of zinc to cadmium being about 200 to 1. The increasing demand for cadmium has led most zinc producers to develop a means for its recovery. The separation and recovery of this byproduct constitutes an important development in the metallurgical field. Zinc sulphide concentrates, principally from domestic sources, are processed at Donora Zinc Works and they assay approximately 60 pct zinc, 30 pct sulphur, 0.37 pct cadmium, and 0.8 pct lead. Concentrates are roasted to convert zinc sulphide to zinc oxide. Sulphur evolved as sulphur dioxide is used to manufacture 60º Baume sulphuric acid by the lead chamber process. The roasted calcine is sintered to remove the remaining sulphur and volatile impurities. Fume from the sintering machines is collected by Cottrell pre-cipitators and sent to the Cadmium Department for cadmium removal. The sintered product, a crude zinc oxide, is then mixed with coke and salt and charged into horizontal retorts for reduction to zinc metal. Furnace residues are then passed through a Waelz kiln which recovers practically all of the remaining zinc as an oxide. This oxide is collected by Cottrell precipi-tators and returned to the sintering plant for further processing. The following discussion covers operating procedure, and equipment used in the Cadmium Department for the manufacture of cadmium and its byproducts. (See attached Flow Sheet, Fig 1.) The production of cadmium may be divided into several steps, each of which will be discussed separately. These steps are as follows: 1. Raw Materials—Sinter Plant Cottrell dust, acid sludge and sulphuric acid. 2. Sulphating—Separation of lead. 3. Purification—Separation of impurities other than zinc. 4. Precipitation—Separation of cadmium from zinc. 5. Briquetting—Preparation of sponge for charging to furnace. 6. Smelting—Distillation of cadmium metal. 7. Remelting—Casting into commercial shapes. 8. Recovery of Rare Metals—Separation of germanium, gallium and indium. Raw Materials The raw material, or Sinter Plant Cottrell dust, from which the cadmium is manufactured, is recovered by Cottrell units collecting fume from two Dwight-Lloyd sintering machines. An average analysis of this dust is 36 pct zinc, 1.5 pct sulphur, 17 pct lead, and 5.5 pct cadmium, with associated elements in smaller amounts. A lesser tonnage of material removed from the sintering machine fans, and called fan cleanings, is also treated for cadmium. It is lower grade material and analyzes approximately 41 pct zinc, 1.2 pct sulphur, 14 pct lead, and 4 pct cadmium. Cottrell dust and fan cleanings are delivered to the Cadmium Department by monorail crane in bell-bottomed dump buckets. Acid sludge and 60" Bauine sulphuric acid are received from the Acid Department. The acid sludge is a mixture of lead sulphate, sulphuric acid and zinc sulphate, and is recovered mainly from the floors of the acid chambers or storage tanks. The acid sludge is delivered to the Cadmium Plant in a lead lined bucket. The 60º Baume sulphuric acid is delivered through a lead pipe to a lead lined storage tank. Sulphating Four well ventilated lead lined sulphating tanks, 8 1/2 ft in diam by 12 ft deep, are used. These are steel tanks lined with 20 lb lead on the bottom and 16 lb lead on the ides, equipped with Hastelloy side agitators. 15 hp motors drive 24 in. propellers at 450 rpm. There are water connections to stuffing boxes to keep sludge from entering the bearings. The tanks are covered with removable wooden lids and are connected to marine plywood

Jan 1, 1950

By I. Iwasaki

The steel industry is facing an unprecedented challenge. I would like to point out the role that flotation technology could play in meeting this challenge by providing high quality raw materials to the steel industry. Of all the technology available to a blast furnace operator, raw material preparation is by far the most important. Raw material preparation has been a key to the success of the Japanese steel industry. The foremost proponent of better raw material preparation was Professor Joseph at Minnesota. He gave a Howe memorial lecture to the AIME audience in the early 1950s, prepared from the lecture notes that he gave in his classes. At about that time he was invited to Japan. It is ironic that the Japanese steel industry listened and made it a success. In order for our steel industry to be competitive, first we must supply high quality and uniform quality raw materials to improve the efficiencies of our blast furnaces. Where does flotation fit in to the iron ore industry then? First, as a primary means for concentrating for oxidized iron ores. Second, to touch up magnetite concentrates for the removal of the last few percent of silica. And third, in the preparation of super-concentrates for direct reduction.

Jan 1, 1984

By H. H. Rachford, D. W. Peaceman

A system of partial differential equations describing miscible displacement of fluids in porous media is derived The system takes into account the influence of gravity, the spatial distribution of permeability, diffusion, and fluid viscosities and densities. A numerical procedure for approximating solutions to the differential systems has been tested for a horizontal two-dimensional geometry. In end-to-end displacements of oil with less-viscous solvents, the numerical solutions exhibited fingering qualitatively similar to that observed in laboratory models. Small random spatial variations in permeability about the mean value are sufficient to initiate fingering. Quantitative comparisons of computed results with laboratory data show good agreement. INTRODUCTION Miscible flooding of oil by solvent is receiving increasing consideration for field use.1-4 Unfortunately, such floods potentially present severe problems in loss of recovery through the by-passing of oil by expensive solvent. Consequently, their economic evaluation requires sound techniques for predicting recovery. The purposes of this work are to present a finite-difference method for calculating the multidimensional displacement of oil by solvent and to investigate the validity of the method by comparing results of calculations with data from displacements in laboratory models.5 The formulation of the method to simulate the model experiments treats a case of limited scope in the description of solvent flooding in the reservoir. The model experiments were carried out with fluids that were assumed to form an incompressible, ideal, two-component system with constant diffusivity. Establishing the validity of the method even in its present form provides a major step toward the goal of quantitatively evaluating individual solvent flooding projects. First, it demonstrates the fea- sibility of calculating the course of displacements which are dominated by an inherent macroscopic instability, i.e., viscous fingering. In addition, the method provides almost the only practical means of examining the effect of the size and extent of reservoir inhomogeneities on the development and propagation of the fingers, taking into account the important influences of diffusion and gravitational segregation. It might be inferred that such studies cannot yield results of practical value because in displacements dominated by macroscopic instability the pattern of finger development and the resulting performance should depend critically on small variations in the geometric distribution of reservoir inhomogeneities. The present method offers the capability inherent in computational techniques of predicting performance reproducibly with any arbitrary distribution of reservoir properties and, as such, provides a means of evaluating the sensitivity of behavior to uncertainties in reservoir definition and, thus, assessing the reliability of prediction of performance. THE PHYSICAL PROBLEM DATA USED FOR QUANTITATIVE TESTS OF CALCULATIONS In this work, a calculation for treating the miscible-displacement process is tested by comparing calculated results with experimental data. The experiments chosen for comparison have been described in detail,5 and the quantitative features are summarized in a later section. Briefly, oil was flooded by solvent of equal density from a thin rectangular channel in Lucite packed with uniform Ottawa sand. Under these conditions, two-dimensional geometry is considered adequate to represent the process. Inasmuch as the present work is concerned with testing of the method by comparison with specific two-dimensional data, the system of equations presented in the succeeding section will be oriented to defining the physical system specifically. THE DIFFERENTIAL EQUATIONS Suppose x, y to be a Cartesian co-ordinate system and define h(x, y) to be the height of a point above a horizontal reference plane. It will be assumed

By Y. C. Liu, G. A. Alers, S. S. Choi

In searching for an explanation for the obvious difference between the copper and the brass type of rolling texture, it is common practice to look for correlations with other properties. For example, there are obvious differences between copper and brass in the critical resolved shear stress, the extent of easy glide or stage I, and the amount of "overshooting)) during single-crystal deformation.' Also, the slip lines in copper are fine and wavy while those in brass are more coarse and better described as slip bands.' Since neutron irradiation is known to make these properties in copper change in such a way as to resemble brass,2'3 an excellent test for these possible correlations is to see whether neutron irradiation produces a corresponding change in the texture, i.e., whether irradiated copper develops a brass-type rolling texture. The experiment would also answer the more important question of whether or not lattice defects like those introduced by neutron irradiation have any effect on the development of rolling textures in fcc metals. Experimental studies using conventional X-ray pole figure techniques are inconvenient because the X-ray detection system must be modified to discriminate against the radioactivity which is induced in the specimen by the necessarily long exposure to neutrons. Nevertheless, some texture determinations have been

Jan 1, 1968

By Francis M. Rice

Before the world-wide depression, the primary purpose of most blast-furnace operators was to produce a maximum tonnage of pig iron per day for each furnace in blast. Some attention was paid to the conservation of labor and raw materials, but the idea was well established that low-cost pig iron was attainable only when each furnace was producing a high tonnage. After the depression had set in, the picture changed considerably. Each blast-furnace operator was forced to run his plant in a manner that best fitted the economical set-up of his company. A great deal of thought was expended on the different methods of operation, always with the idea of making each product in a way that would best serve his company financially. Because of this abnormal condition, the blast-furnace man was compelled to indulge in various practices of which many had been believed to be next to impossible up to that time. The ultimate purpose of these innovations was either one or a combination of the following: 1. To produce only enough pig iron for immediate consumption at a minimum cost. 2. To produce gas for boiler or mill use to supplant some higher priced fuel. 3. To consume the coke produced at the coke plant, which was often viewed as a byproduct. 4. To protect the cash position of the company. These conditions were met by diverse methods, some of which were: 1. Slow or decreased wind. In some instances the blast blown was held as low as 25 per cent of the normal volume. 2. Intermittent operation, in which the furnaces were shut down or "fanned" at frequent intervals.

Jan 1, 1935

By Francis M. Rice

Before the world-wide depression, the primary purpose of most blast-furnace operators was to produce a maximum tonnage of pig iron per day for each furnace in blast. Some attention was paid to the conservation of labor and raw materials, but the idea was well established that low-cost pig iron was attainable only when each furnace was producing a high tonnage. After the depression had set in, the picture changed considerably. Each blast-furnace operator was forced to run his plant in a manner that best fitted the economical set-up of his company. A great deal of thought was expended on the different methods of operation, always with the idea of making each product in a way that would best serve his company financially. Because of this abnormal condition, the blast-furnace man was compelled to indulge in various practices of which many had been believed to be next to impossible up to that time. The ultimate purpose of these innovations was either one or a combination of the following: 1. To produce only enough pig iron for immediate consumption at a minimum cost. 2. To produce gas for boiler or mill use to supplant some higher priced fuel. 3. To consume the coke produced at the coke plant, which was often viewed as a byproduct. 4. To protect the cash position of the company. These conditions were met by diverse methods, some of which were: 1. Slow or decreased wind. In some instances the blast blown was held as low as 25 per cent of the normal volume. 2. Intermittent operation, in which the furnaces were shut down or "fanned" at frequent intervals.

Jan 1, 1935

By Dever Ashmead

FROM time to time metal-mine engineers have inquired why anthracite mines and their preparators are rarely operated on the two or three-shift basis. The subject may be approached as affecting: labor, development, the underground workers, the preparator, the outside workers, capital, the supply account, power consumption, the storage of coal over various shifts, railroad car supply, and the market. LABOR From the start, the adoption of a plan of three full-shift operations in a day would cause difficulty with the colliery employees, for they have never worked on that plan and would show their resentment by suspending work. Even if they could be induced to work according to this schedule they would not be as efficient, for they would be working more or less unwillingly at hours at which they are accustomed to rest. Operation on a three-shift basis would necessitate triple manning of each working place, and dissensions would arise between the men, for each shift would claim that the preceding shift had taken undue advantage and had not left as favorable conditions as it had found. To obviate these disputes it might be necessary to let out the work to a contractor, who would hire his helpers to mine out the chamber, or breast. The state mining law requires that a miner be put in charge of each working place. To conform with this provision he would have, to hire three helpers and two miners to mine the breast. The labor unions have been trying to abolish the subcontractor in mine work and any method of working that would cause his return, however innocent in purpose, would result in labor disturbances.

Jan 2, 1922

By E. J. Rapperport, E. D. Levine

The boundaries of the (a +ß) field in the Al-Li system were determined between 150°and 550°C utilizing quantitative metallography and lattice-parameter measurements. The solubility of lithium in aluminum decreases from 12.0at. pct Li at 550°C to 5.5 at. pct Li at 150°C. P Al-Li is saturated with aluminum at 45.8 at. pct Li and has this boundary value constant over the temperature range 150°to 550°C. THE solid solubility of lithium in aluminum has been determined by several investigators, 1-6 but, as shown in Fig. 1, there is little agreement among the various determinations. The earliest investiga-tions'-' are suspect because of the use of impure materials. Although high-purity materials were employed in more recent work,4'5 the experimental techniques may have led to contamination of the specimens. Probably the best work has been that of Costas and Marshall,6 who obtained close agreement between results obtained by two independent phase-boundary techniques: electrical resistivity and mi-crohardness. No detailed studies of the solubility of aluminum in the bcc ß phase, Al-Li, have been reported. Cursory investigations1,2,6 have indicated only that the (a+ß) -p boundary lies between 40 and 50 at. pct Li and is relatively independent of temperature. The present work was undertaken in order to provide an independent check on Costas and Marshall's determination of the solubility of lithium in aluminum, to extend knowledge of this solubility limit to temperatures below 225°C, and to make an accurate determination of the solubility of aluminum in Al-Li. EXPEFUMENTAL Alloy Preparation. In view of the difficulties encountered in previous investigations of the A1-Li system, close attention was paid to the use of methods of alloy preparation and treatment that would minimize contamination. Aluminum sheet (99.99 + pct Al) was vacuum-induction melted in a beryllia crucible to remove hydrogen. Lithium (99.9 pct Li) was charged with pre-melted aluminum into a beryllia crucible, in a helium-filled drybox. The crucible was sealed in a Vycor tube and transferred from the drybox to an induction furnace. Melting of alloys was performed by induction heating in a helium atmosphere. Solidification was accomplished by means of a suction apparatus, shown in Fig. 2, in which the alloy was forced by changes of pressure into a 3/16-in. inside diam closed-end beryllia tube. This technique produced rapid solidification of a small portion of the melt, resulting in alloys with a high degree of homogeneity. Typical lithium distributions are presented in Table I. Transverse sections 1/8 in. long were cut from the alloy rods, and each section was split in half longitudinally. One half of each section was analyzed for lithium, and the opposing halves were employed for phase-boundary determinations. Lithium contents were determined by flame photometry with an accuracy of 1 pct of the amount of lithium present. Thermal Treatments. Homogenization and equilibration heat treatments were performed in electrical-resistance furnaces with temperatures controlled to ± 2OC. Calibrated chromel-alumel thermocouples were employed to measure temperature. Homogenization was performed in helium-filled l?yrex tubes for 1 hr at 565°C. The encapsulated specimens were then transferred directly to furnaces maintained at lower temperatures for equilibration. Equilibration times were 2 hr at 550°C, 8 hr at 450°C, 27 hr at 350°c, 90 hr at 250°c, and 285 hr at 150"~. These times were chosen on the basis of conditions employed by previous investigators. Alloys were quenched from the equilibration temperatures by breaking the capsules into a silicone oil bath. By performing all possible operations either in sealed capsules or in a helium-filled drybox, the specimens were given minimum exposure to the atmosphere. Quantitative Metallography. Metallography of Al-Li alloys is difficult because of the atmospheric reactivity of the ß phase. It was found possible, however, to prepare surfaces of good metallographic quality by preventing contact with moisture during preparation. Grinding through 4/0 paper was performed in the drybox. The specimens were then transferred under kerosene to the polishing wheel. Three polishing stages were employed: 25-p alundum with kerosene lubricant on billiard cloth, 1-µ diamond paste on Microcloth, and 1/4-p diamond paste on Microcloth. Between stages the samples were cleaned by rinsing in trichloroethylene and buffing

Jan 1, 1963

By John Freeman

THIS paper relates entirely to the casting of brass under fluid pressure in steel dies. Die castings of metals and alloys of low melting point have been available for many years but the development of brass die castings has been relatively recent, occurring within the past five years. The successful development of brass die castings has resulted from the availability of alloy steels that would give satisfactory life as dies and the development of suitable die-casting machines. The melting point of copper is 1084° C. (1983° F.) and of a high brass about 900° C. (1652° F.), as compared to 327.5° C. (621.5° F.) for lead, 419.4° C. (786.7° F.) for zinc and 658.7° C. (1217.7° F.) for aluminum, temperatures that are indicative of the casting temperatures required for the various types of alloys, of which the melting points are somewhat lower than those of the pure metals.

Jan 1, 1935

By W. W. Odell

ONCE it was believed that anthracite or coke were the only fuels generally available and suitable for the generation of water gas, particularly so when this gas was made in the generators of standard carburetted water-gas sets such as are commonly used in the manufacture of city gas. During the past 8 years, practice has changed considerably and it is -now common to find gas plants operating without anthracite or coke and using bituminous coal in the generator. This change in fuel has appreciably increased the marketability and sales of certain coal producers' products; accordingly it is of interest to coal operators and others to know the reason for this change, the present trend in practice and the adaptability of various coals for generation of water gas. This paper briefly discusses these conditions and some of the factors relating thereto. BITUMINOUS COAL NOT IDEAL BUT CHEAPER THAN COKE In spite of many changes which have been made in both process and generating apparatus for using bituminous coal as generator fuel more efficiently, in general it is not an ideal fuel for this purpose. It is supplanting coke because it costs less; it is so much cheaper per ton delivered at the gas works that water gas made therefrom costs less per unit-volume than that made from coke, even though the quantity of generator fuel consumed per therm (100,000 B. t. u.) of gas made is greater with coal. This is the reason why so many city gas plants, as well as others, are using bituminous coal instead of coke.

Jan 1, 1927

By L. W. Holm

This study shows that in the presence of foam, gas and liquid flow separately through porous media representative of reservoir rock. These results were obtained by using tracer techniques to measure the flow of the gas and liquid comprising the foam. Foam does not flow through the porous medium as a body even when the liquid and gas are combined outside the system and injected as foam. Instead, the liquid and gas forming the foam separate as the foam films break and then re-form in the porous system. Liquid moves through the porous medium via the film network of the bubbles and gas moves progressively through the system by breaking and re-forming bubbles throughout the length of the flow path. The flow rates of the gas and liquid are a function of the number and strength of the films in the porous medium. There is no free flow of gas; i.e., no continuous gas phase. On the basis of these results, foam can be expected to improve a water flood or gas drive by decreasing the permeability of the reseruoir rock to a displacing liquid or gas. This improves the mobility ratio and thus the conformance of the flood. INTRODUCTION Foam is formed when gas and a solution of a surface active agent are injected into a porous medium either simultaneously or intermittently. During the past few years, several papers have been published on the subject of foam flow in Dorous media. Foam has been used successfully in the removal of capillary water blocks from producing formations.''2 The use of foam in gas storage reservoirs to reduce gas leaks and to increase storage capacity has been considered in recent years. Foam has also been investigated as an oil displacing agent,3-5 and as an agent to improve the mobility ratio in a waterflood.6-10 However, the mechanism by which the gas and liquid phases comprising the foam flow through a porous medium has nor been described adequately. Normally, when two immiscible phases (gas and liquid) flow concurrently through a porous medium, each phase follows separate paths or channels. At given saturations of the two phases, a certain number of channels are available to each phase, and as saturations change, the number and configuration of the channels available for each phase also change. The effective permeability of each phase is a function of the saturation of that phase only, and the flow of each phase can be described by Darcy's law. When foam is present, the effective permeability of the porous medium to each phase is greatly reduced compaced with permeabilities measured in the absence of foam.6,11-13 Based upon the observed flow of surfactant solutions and gas in capillaries, it has been concluded that the gas and liquid may flow separately or they may flow combined as foam. At least four mechanisms have been postulated to explain how fluids flow with foam present: 1. A large portion of the gas is trapped in the porous medium and a small fraction flows as free gas, following Darcy's law.9 2. The foam structure moves as a body; the rate of gas flow is the same as the rate of liquid flow. 6,13 3. Gas flows as a discontinuous phase by breaking and re-forming films. Liquid flows as a free phase.12 4. A portion of the liquid and gas move as a foam body while excess surfactant solution moves as a free phase.14 It also has been suggested that different flow mechanisms exist for high quality (dry) foams made from dilute surfactant solutions and for foams made from more concentrated solutions. Studies conducted on the flow of foam through capillaries have shown that a plug-type flow occurs and that foam flows as a body.6,15 Fried also has described the flow of foam through porous media as

Jan 1, 1969

By F. D. Rosi, C. A. Dube, B. H. Alexander

WHEN a deformed polpcrystalline metal is heated to a sufficiently high temperature, a recrystallized structure develops which consists of small, essentially stress-free grains. This transformation is referred to as primary recrystallization. Under certain conditions, on prolonged annealing of the specimens, a type of grain coarsening occurs in which a small number of grains commence to grow at various points by devouring the neighboring finegrained primary structure, which, in itself, exhibits a marked stability toward normal grain growth. This grain coarsening process has been referred to by Burgers' as "secondary recrystallization" or "exaggerated grain growth." Although much work has been done on recrystallization and growth processes, present knowledge of the factors which determine the occurrence and growth of secondary grains is inadequate for the advancement of a theory which accounts for the observed characteristics of this recrystallization phenomenon. In this respect, it would be important to make measurements of the velocity of growth of these large secondary grains. The early work of Feitnecht2 on aluminum showed that the size of secondary grains increased with temperature and time, suggesting that such measurements would be possible. More recently, Burgers1 found that the growth velocity of these grains in aluminum was constant over a large time interval, as is generally found for the growth velocity of primary grains in a uniformly deformed test piece.3-5 It is reasonable to expect that the determination of the activation energy of the secondary growth process might lead to a better understanding of the underlying atomic mechanism. This investigation, therefore, is one of a series primarily designed to measure the growth velocity of secondary grains at various temperatures for silver, copper, and aluminum. It is hoped that these studies along with those of orientation relationships, will establish a sound basis for theorizing as to the origin and nature of the secondary transformation. Experimental Procedure The metal used in the present investigation was high-purity silver (999.9 fine), which was supplied in the form of cold-rolled plates 0.250 in. thick. These plates were annealed at 500°C for 1 hr and then straight-rolled to a thickness of 0.04 in. in three reductions of approximately 45 pct, followed in each case by an anneal at 450°C for 1/2 hr. The 0.04 in. sheets were given a final reduction of approximately 50 pct, which resulted in a thickness of 0.02 in., thereby insuring two-dimensional crystal growth. Individual specimens of this material about 1x3 cm were used for all heat treatments, unless otherwise noted. The annealing was carried out under an atmosphere of argon in an Inconel tube furnace whose temperature was controlled to within -+2°C. Metallographic examination of the secondary transformation was accomplished by mechanically polishing the specimens on one side to approximately one half their thickness through 2/0 metallographic emery paper, and then electrolytically polishing in a solution of potassium ferrocyanide and sodium cyanide. With a current density of approximately 20 amp per sq dm, the time required to obtain a satisfactory surface varied from 3 to 5 min. Standard potassium bichromate was used to etch the electrolytically polished surfaces. A heavy etch with this solution produced a sharp contrast between the secondary grains and the fine-grained primary structure, darkening the latter while leaving the large secondary grains bright. All area measurements of the secondary crystals were made with a planimeter on enlarged tracings of the grains.

Jan 1, 1953

W. R. CRANE, State College, Pa.-The use of mine models for instructional purposes, both in the classroom and for more general work, as in the engineer's office, is of so much importance that I was pleased to FIG. 1.-MODEL OF A TIMBERED STOPE. see Professor Stock's paper which supplements a fairly voluminous literature on the subject. I have been interested in model making for instructional purposes for nearly 20 years and have tried my hand at practically every phase of the work, and have also employed practically every kind of material that

Jan 1, 1918

By E. Swartzman

THE free-swelling index, a numerical value for the free-swelling properties of coal, is being used to an increasing extent in specifying coal for burning in various types of equipment. The empirical standard ASTM method for determining this index uses, as a source of heat, a gas burner which requires frequent calibration because gas pressures are not constant, relatively small changes in gas pressure resulting in rather wide variations in the temperature attained in a crucible and thus in the resultant size of the coke button. Furthermore, the quartz crucibles specified for the test are not standard equipment, and relatively small variations in dimension and wall thickness from those specified often result in rather wide variations in the resultant size of the button.

Jan 10, 1951

By H. F. Yancey, O. L. Furse

For several years the Bureau of Mines at its Northwest Experiment Station, in cooperation with the Mines Department. of the University of Washington, has been studying the breakage and degradation of coal. The first phase of the study was devoted to the determination of the friability of many coals of various ranks and comparison of various methods for estimating friability.' A study of the relative ease or difficulty with which various coals are reduced to the fine size required for use as pulverized fuel followed the completion of this work. Baltzer and Hudson2 list twelve research organizations in the United States, two in England, one in Germany and one in Canada that are reported to be engaged on this problem; showing the general appreciation of the need for a simple method of estimating the grindability of different coals. Hardgrove,3 ho has advanced a method for estimating grindability, points out that pulverizer tests of different coals are incomplete and unsatisfactory. He compares such tests to that of a boiler test made without knowledge of the calorific value of the coal. Frisch arid Holder4 also stress the same point. They state that,

Jan 1, 1934

By R. E. Jenkins

The Bell Canyon member of the Delaware Mountain group has yielded quite a large number of fields in which completion and production problems have been numerous and complex. Reserves are difficult to estimate due to the problem of evaluating the formation water saturation, and the feasibility of water flooding is questionable. Extensive laboratory investigations were undertaken to determine if normally measured rock and contained fluids properties could account for many of the peculiar characteristics of the formation. A statistical study or routine core-analysis data was made. Capillary-pressure data were obtained by several techniques. Fresh-water and brine permeabilities were measured and relative permeabilities of oil, water and gas were determined. Some qualitative wetta-bility tests were performed, and the petrography of a few thin sections was studied. The results of this work are presented, with typical or average data shown for each test. The permeability -to- water characteristic of the Delaware was found to be abnormally poor. Correlations of laboratory and field performance data indicate high water saturations in much of the formation. Pore geometry is highly uniform. INTRODUCTION The Delaware formation has undergone extensive exploration and development in the past few years. This has resulted in the discovery of quite a number of fields—producing oil for the most part. A large percentage of the productive wells have produced water along with the oil. Often there is no apparent pattern for the percentage of water cut experienced. In several instances vertical displacments of over 200 ft have been established between communicating wells in which the formation appears to be about the same, yet the structurally high wells yield a much higher water cut than the lower wells. Drill-stem tests have contributed little to well completion because they nearly always show small amounts of water (usually mud filtrate), regardless of what is produced later in the life of the well. Other formation evaluation methods have had no more than limited success in indicating ultimate productivity. Consequently, predicting the type of fluid productivity of Delaware wells has been very difficult. Hydraulic fracture treatments are almost universal, and unstimulated Delaware wells have not exhibited the productivity that normally would be expected of wells with the specific permeabilities encountered. Some operators have indicated that their Delaware wells need frequent re-stimulation. The uncertainty of reservoir water saturations reported for the Delaware has made difficult the task of evaluating oil in place in the reservoirs and estimating primary recovery. The unreliability of this data also will cause feasibility studies for water flooding or other secondary-recovery methods to be problematical. Several opinions have been voiced to explain why the Delaware performs as it does. Chronically poor well completions, dynamic water and tilted water tables, capillary inequi-libria, peculiar relative permeability characteristics and oil-wetness are among the suggested reasons. The dual purpose of this paper is (1) to describe the principal rock characteristics, and (2) to present an evaluation of those characteristics so that approaches can be made to explain the irrational behavior of wells completed in the Delaware. STUDY OF ROUTINE CORE-ANALYSIS DATA A statistical study of routine core-analysis data has been made to relate fundamental rock properties and characteristics of the formation to well productivity. For the most part, well production data were obtained from operators and augmented by production data from commercial information services. Only data which were available in detail and which were considered to be accurate were used. The core data used were obtained on samples from the perforated or open interval only and, thus, may not always represent the total productive interval in a well. All the core-analysis data included in this study are from the Bell Canyon member of the Delaware and were obtained by "plug-type" techniques, as opposed to whole-core or full-diameter techniques. Porosity values were obtained by the summation-of-fluids technique, permeability values are air permeabilities corrected for slippage to an equivalent liquid permeability, and the oil and water contents were determined by means of a high-temperature downdraft retort. All the procedures used are discussed at length in Ref. I. The core-analysis data were sorted

By Newell G. Alford

At its meeting in the fall of 1937, the Executive Committee of the Coal Division considered the growing scarcity of young engineers entering coal mining with serious intentions. This scarcity was the cause of considerable alarm and a committee consisting of C. T. Hayden, E. A. Holbrook, C. E. Lawall and L. E. Young, with the writer as chairman, was appointed to gather factual data on the current trend. A questionnaire1 was designed and mailed to the heads of the 60 mineral technology schools listed by Prof. W. B. Plank in his article in September 1937.2 Replies were received from 46 institutions, not all from heads of coal-mining courses but all from men that at one time or another have had experience with some kind of coal-mining curricula and know current student impressions. Our committee is indebted to all of these gentlemen for their cooperation. Our committee hoped by this means to quickly reach the root of the trouble and make a set of comprehensive recommendations to the Coal Division for relieving the industry immediately from the growing dearth of youth who yearn for coal-mining careers, but the condition is more serious than at first diagnosed. We must now refer the question back to the Coal Division, with the recommendation that the Division get the industry's permission for still another major operation on its frame of mind. In addition to 10-year statistics on the first pay received by graduates in coal mining and other technical work, we requested enrollment data for 20 years from all schools with either mining engineering or mineral technology curricula. Nine leading questions were also plied, as shown in the Appendix. Every one of the answers was significant and interesting. Fortunately, we encountered positive frankness that was extremely helpful.

Jan 1, 1938