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By Edward Estabrook

THIS paper gives a brief account of the geologic and production problems encountered in the Grass Creek oil field, the methods used in their solution, and the beneficial results obtained from the work. The author wishes to acknowledge the assistance received from J. H. Pearson and Miss Ninettta A. Davis in the collection of the data and the preparation of the cross-sections. Permission for its publication was given by the officials of the Midwest Refining Co. and the Ohio Oil Co. The Grass Creek oil field is located in Ts. 98-99 W., R. 46 N., Hot Springs County, Wyo. The productive area includes about 2 1/2 mi. (4 km.) on the apex of a great anticlinal fold occupying more than 150 sq. mi. Fig. 1 shows the structural contours of the field. Oil was dicovered in the field in June, 1914; development proceeded rapidly and production rose to a maximum in 1918. The marketed production has been approximately as follows: BARRELS BARRELS 1915 94,073.5 1918 2,946,774.27 1916 1,404,183.97 1919 2,000,584.84 1917 2,780,697.51 1920 1,485,080.94 About 350 wells, 800 to 1500 ft. (243 to 457 m.) deep have been drilled to reach the upper oil sands; two companies, the Ohio Oil Co. and the Midwest Refining Co., operate the entire field.

Jan 2, 1922

By L. A. Roe, E. A. Elevatorski

Wollastonite, named after William H. Wollaston, an English chemist, is a calcium metasilicate, CaSiO3; CaO: 48.30%, SiO2: 51.70%. It has a short history as an industrial mineral. The earliest production of wollastonite is reported to be from a deposit near Code Siding, located north of Randsburg, CA. At this locality small tonnages of wollastonite were quarried during 1933-34 and 1938-41, and processed into mineral wool. This operation was largely experimental and virtually no United States production was again reported until the 1950s when a large deposit near Willsboro, NY, was developed by the Cabot Corp. A processing plant was placed onstream in 1953, with nearly continuous production to date. It is currently operated by NYCO, a division of Processed Minerals, Inc. Since 1958, wollastonite deposits in the Little and Big Maria Mountains of Riverside County, and in the Panamint Range of Inyo County, both in California, have operated intermittently for production of both ornamental and commercial wollastonite. During 1980, the United States was the major producing country, furnishing about 75% of the world's output. Current production comes from Finland, Mexico, India, and Kenya. Small amounts have been shipped intermittently from the USSR, New Zealand, Republic of the Sudan, Republic of South Africa, and Namibia (South-West Africa). The principal use of wollastonite is in the manufacture of plastics. Other uses are for paints, ceramics, adhesives, fluxes, glazes, thermal insulation board, and refractory products. Mineralogy Pure wollastonite, CaSiO3, has the composition of 48.3% CaO and 51.7% SiO2. However, it is seldom found in the pure state due to the ease with which it takes into solution the metasilicates of manganese, magnesium, iron, and strontium. Predominantly, wollastonite occurs as a contact metamorphic deposit forming between limestones and igneous rocks. Commonly associated minerals are garnet, diopside, epidote, calcite, and quartz. It has a specific gravity of 2.8 to 3.0, and hardness of 4.5 to 5 on Mohs' scale. When pure, it has a brilliant white color, but with impurities it may be grayish or brownish. Luster is vitreous to pearly. Melting point of wollastonite is about 1540ºC. Wollastonite occurs in coarse-bladed masses, rarely showing good crystal form. It is usually acicular or fibrous, even in the smallest of particles. The most unique property of crushed and ground wollastonite is its cleavage. Fragments of crushed wollastonite tend to be needle-shaped, imparting a high strength, and this property is the basis for many of its uses. The fiber lengths are commonly in the ratio of 7 or 8 to 1, length to diameter. The average diameter of wollastonite is 3.5 µm. Some crystals of wollastonite fluoresce under short-wave or longwave ultraviolet light, or both, with colors ranging from yellow-orange to pink-orange. Specimens may also show phosphorescence. The acicularity of wollastonite is a property of considerable importance to the marketplace. The plastics industry makes utilization of high aspect ratio grades of wollastonite (20:1) for reinforcing thermoplastics and thermoset polymer compounds. The naturally high pH of 9.9 (10% water slurry) is a prime property to the coatings industry. The coatings industry uses milled grades of wollastonite as a pH stabilizer in interior and exterior PVA and acrylic latex systems. Processed wollastonite can have a G.E. brightness of 90 to 93. Chemically, wollastonite is inert and this property makes it useful as a filler and reinforcing agent. There are two polymorphs of calcium silicates: wollastonite, a low temperature form, and pseudowollastonite, a high temperature

Jan 1, 1983

By J. S. Kirkaldy, D. H. Weichert, G. R. Purdy

Two-phase diffusion couples have been used to simulate the growth of proeutectoid ferrite in ternary Fe-C-Mn austenites. It has been shown, theoretically and expermentally, that the results fall into two classes: a high-super saturation class in which the major role of manganese additions is to influence the boundary conditions for carbon diffusion; and a low-supersaturation class in which the partition of manganese is required. In the latter case, a drastic inhibition of the reaction rate is to be expected. As an aid to the kinetic analysis, a portion of the iron-rich comer of the Fe-C-Mn constitution diagvam has been determined. The conclusions drawn from this work have a direct bearing on the kinetics of the grain boundary ferrite precipitation reaction and thus yield insight into the manner in which alloying elements can influence the rate of austenite-decomposition reactions. THE role of alloying elements in the austenite-decomposition reactions has provoked considerable interest, since it is apparent that an understanding of this phenomenon will yield insight into the harden-ability problem. In the present investigation, attention is focused upon the proeutectoid-ferrite transformation in the system Fe-C-Mn, and upon the manner in which manganese additions affect the growth rate of ferrite. When hypoeutectoid austenite is supersaturated, the ferrite first formed usually exhibits two distinct types of morphology. At low super saturations, grain boundary layers grow into the austenite grains with an approximately planar interface, and usually possess at least one incoherent phase boundary. At high supersaturations, Widmanstiitten plates appear, which bear an orientation relationship' to the parent austenite. In this case, there is a chance of partial lattice matching along the sides of the plates and an attendant semicoherent interface structure. Purdy and Kirkaldy2 have used a two-phase binary Fe-C diffusion couple to demonstrate that carbon volume diffusion controls the incoherent reaction, while Rouze and rube,' using thermionic-emission microscopy, have shown that the thickening of Widmanstatten ferrite plates is appreciably slower than expected for carbon-diffusion control. This suggests that the plates are bounded by partially coherent, low-mobility interfaces. The redistribution of alloying elements during transformation has been the object of studies by Aaronson4 and owmman,5 who have shown that no alloy partition occurs during ferrite precipitation in the systems Fe-C-Cr and Fe-C-Mo, respectively. More recently, Aaronson et al.6 have shown that some manganese partition occurs at low super-saturations in the system Fe-C-Mn, but that no partition occurs at higher super saturations. Pickle-simer et al.7 observed that no manganese partition occurred during the early stages of the pearlite transformation in a manganese steel, and concluded that volume diffusion of the alloying element is not the rate-deter mining factor. The diffusion coefficients pertinent to this investigation have been measured by Wells, Batz, and Mehl8 (carbon in austenite), R. P. smith9 (carbon in ferrite), Wells and Mehl 10 (manganese in austenite), and Kirkaldy and Purdy11 (diffusion of carbon on a manganese gradient in austenite). Kurdjumov 12 has shown that the diffusivity of substitutional elements in ternary austenites up-quenched from martensite may be greatly enhanced, due, apparently, to the presence of a persistent defect structure. The recent work of Krauss 19 showing high densities of tangled dislocations in reversed Fe-Ni martensite is in agreement with this conception. THEORETICAL Diffusion in ternary or higher-order systems may be described with the aid of Onsager's extenbion of Fick's first law,14 in which the flux of each of the n components is assumed to be a linear function of all concentration gradients:

Jan 1, 1964

By J. A. Kost

The contract objective was to evaluate the effectiveness of available dust-control technology for double-drum shearers. Eight underground surveys were conducted to evaluate drum design, drum spray nozzle locations, ranging-arm sprays, water quantity, wetting agents, and cutting techniques. The final report is made up of eight dust-control technique reports, each discussing, details of the individual mine surveys.

Jan 1, 1985

By S. K. Tarby, A. E. Rathke

A series of 0.21 pci carbon steel melts was processed under conditions which sinzulated industrial vacuum degassing practices. The results indicated that the efliciency of carbon deoxidation was not significantly increased by vacuunz degassing at chamber pressures below 100 torr. The two common phenomena of vacuu?rz carbon deoxidation, i.e.,an unaccountable carbon loss and nonequilibrium deoxidation, were observed in this study. Oxygen from adsorbed and chenzically combined water of certain refractory structures was probably responsible for the unaccourttable carbon drop. The nonequzlibrium deoxida-tion phenomenon was adequalely correlated by a bubble nucleation )mechanism. Although the major limiting factor in oxygen removal from these melts contained in alumina crucibles could not be eslablished with certainty, there was some evidence that melt-refractory interactions were not the most imp-portant limiting factor. CONSIDERABLE attention has been given to the use of carbon in conjunction with vacuum degassing* as a deoxidation technique. An advantage of utilizing the reaction: for deoxidation purposes is that the reaction product is gaseous and hence can be effectively removed from the melt. The pressure dependency of Eq. [I] is illustrated by the expression for the thermodynamic equilibrium constant, K: where pco is the partial pressure of carbon monoxide, and hc and ho are, respectively, the Henrian activities of carbon and oxygen in molten steel. The thermodynamic aspects of the C-0 reaction in molten Fe-C-0 alloys have been investigated extensively. Theoretical predictions based on Eq. [2] indicate that, at the chamber pressures reached in most vacuum degassing units, carbon is the most effective deoxidizer that can be obtained. ~ornak' has compared industrial values of carbon and oxygen contents with values calculated from theory, and has shown that on a commercial basis vacuum carbon deoxidation has not achieved the degree of success that is predicted from theoretical considerations of the C-0 reaction. The use of industrial units to determine the reason for this deviation is limited by economics and the difficulty in controlling critical process variables. Therefore laboratory-sized experiments in this area should yield valuable information. Investigations on vacuum carbon deoxidation have been made in experiments conducted under vacuum induction melting conditions where pressures in the low micron range, long treatment times, exposure to highly dynamic vacuum conditions, and relatively quiescent bath conditions have been maintained. Inve~ti~ators~~~ utilizing vacuum induction melting for the production of high-purity iron by carbon deoxidation have concluded that, under high vacuum conditions, melt-refractory interactions constantly supply oxygen to the melt. Thus, it has been suggested that refractory dissociation rather than the C-0 reaction establishes the lowest possible oxygen content of a melt. Thomas and Moreau4 and Bennett, Protheroe, and ward5 have studied carbon deoxidation of Fe-C alloys melted in magnesia crucibles under reduced pressures. The results of both studies differed considerably from those predicted by theory, and the limiting factor for lower oxygen contents was attributed to melt-refractory interactions. Because the refractory material used in both investigations was magnesia, no quantitative measure of crucible reaction could be made and the amount of carbon consumed during treatment was utilized as an indirect indication of the extent of crucible reaction. Studies concerned with the determination of the minimum oxygen content attainable in pure iron and Fe-C alloy material vacuum-induction-melted in various crucible materials have also been conducted."' The suitability of a crucible refractory for use under vacuum conditions appears to depend upon the major refractory constituent, the amount and type of impurity oxides, and the composition of the melt. Meadowcroft and Elliott9 have presented a theoretical review of the type and extent of various refractory reactions which should be considered in vacuum refining. ~eadowcroft'~ considered the vacuum degassing process to be dependent upon the "carbon boil" and has proposed that a part of the difference between the experimental and theoretical results for vacuum carbon deoxidation may be explained by the fact that the pco term in Eq. [2] is not the chamber pressure. Instead, the pressure necessary for carbon monoxide

Jan 1, 1970

By S. J. McCarroll

Fig. 1—The belt shown at right carries filter cake to mixing station over calciner. Crude ore conveyors appear in right background. THE Three Kids mine, some six miles east of Henderson, Nev., is in a typical southwest desert area, with high dry summer heat and cool to cold winter seasons. The manganese deposit was located during World War I.' During this period 15,000 to 20,000 tons of ore assaying up to 41 pct manganese were shipped. Interest in the deposit was not revived until the middle thirties, when experiments on the ore were initiated. Test work indicated possible recovery of only 70 pct by flotation, but in 1941 additional work was done at the Boulder City pilot plant of the U. S. Bureau of Mines and also by M. A. Hanna Co. As a result, the Manganese Ore Co. was formed and a plant utilizing the SO2 process was constructed. Numerous operation difficulties ensued, and the plant. was closed when the manganese situation in the country eased. In 1949 Hewitt S. West initiated negotiations to acquire the plant. In 1951 Manganese, Inc., was formed and contract entered into with the General Services Administration to supply 27 million units of metallurgical grade manganese in the form of nodules to the national stockpile. A second contract was made to upgrade 285,000 tons of stockpile ore. Test work was undertaken by the Southwestern Engineering Co. and likewise by the Boulder City pilot plant at the U. S. Bureau of Mines. Results obtained indicated the commercial feasibility of the flotation process. Construction of the plant, which is shown in Figs. 1 and 2, was started in June 1951, and operations on a break-in basis began in September 1952. Apart from the usual starting difficulties two major disasters caused serious setbacks, one a kiln failure in February 1953, and the other a fire that destroyed the flotation building in June of the same year. The nodulizing section of the plant resumed operation in November, and the flotation section in January 1954. The ore minerals are chiefly wad,* with minor amounts of psilomelane, and occur in sedimentary beds of volcanic tuff. The ore is overlain with beds of gypsum which outcrop or may be covered with surface gravel. Intermediate beds of red and white tuff occur frequently with lenses of red and green jasper and stringers of gypsum and calcite. Small amounts of iron are present; lead content averages about 1.0 pct and minute amounts of copper and zinc are found. Barite, celestite, and bentonite are present. Since these are made up of minute asicular crystals, moisture content is very high, averaging about 18 pct. Ore reserves have been estimated at 3 million tons averaging 18 pct Mn2 and up to 5 million tons after grade is dropped to 10 pct Mn. A good part of the orebody was stripped of overburden by the previous operating company . Approximately 50 pct of the ore, representing more than 60 pct of the manganese, can be mined by open-cut methods. A system for underground min- . ing has not yet been decided on. Open-cut mining with benches of 20 ft has proved satisfactory. Although the ore is soft and appears dry and dusty it has a certain resilience, probably due to the porosity and moisture which makes drilling and fragmentation difficult. Wagon drills have been abandoned in favor of the Joy 225-A rotary drill which will put down a 43/4 -in. hole at the rate of 2 ft per min. Holes are spaced in a pattern with 8 to 9-ft centers. Forty percent powder has been used, but better breaking to 2-ft size is obtained with low velocity bag powder of 30 pct strength. Loading is done with one 21/2-yd shovel, and cleanup follows with one D-7 bulldozer. The ore is hauled with Euclid trucks about 1000 ft from the pit to a blending pile, where the daily mine production is spread in layers by bulldozing until approximately one month's mill feed is accumulated. A new pile is then started and mill feed is drawn from the first pile by one 13/4-yd shovel and Euclid trucks, with a haul of approximately 500 ft. Mining is performed by an independent contractor with engineering and supervision by the company staff. Early test work indicated that the manganese could be floated with soap, a wetting agent, and fuel oil to give a recovery of better than 75 pct with a grade of 43 pct Mn. The concentrate when nodulized with coke would upgrade to 46 pct Mn or over, and the lead volatilized to 0.6 pct residual.

Jan 1, 1955

By Charles S. Larkey

Numerous papers have been published on the use of graphic methods for determining the best curve for estimating the production decline of oil wells but, as far as the writer has been able to ascertain, nothing has been published showing how curves may be worked out mathematically that will conform most closely to the production data under consideration in any given instance; hence the writer has endeavored to show just how such application can be made. Among the valuation engineers, two types of curves are in current use for the representation of the decline in production of oil wells. One may be represented by the equation, y = krx; this is sometimes known as a percentage curve, for the production for any period is multiplied by a constant rate or percentage to obtain the production for the succeeding period. It appears as a straight line on semilogarithmic cross-section paper. The other curve may be represented by the equation, y = kxn, and is shown as a straight line on logarithmic cross-section paper. In each equation, y represents the number of barrels produced in a given period of time, and x the successive periods of time. The other letters are constants to be determined for each well, or group of wells considered in arriving at the most probable curve to represent the rate of production for a given property. From this the underground reserves may be estimated by extrapolation, or by extending the curve beyond the last known period of production to show the most probable production values for the future. Application to the Burbank Pool Fig. 1 relates to a property in the Burbank Pool, Osage County, Okla. The production is shown as an average per well per month, is plotted to the vertical scale of barrels on the left-hand margin and to the horizontal scale of months at the bottom of the chart. In column y, the number of barrels is listed beginning with May, 1922, as the first month on which to base a decline curve. The type of curve used is of the form, y = krx, or, expressed in logarithms, log y = log k + x log r, in which log k and log r are constants to be determined so that the curve will most closely approximate the production data given.

Jan 1, 1925

By M. F. McCarty, R. S. Olson

New organic flocculants of high-molecular weight are replacing lime, glue, and starch in liquid-solid separation. Of these synthetic materials, poly-acrylamides are outstanding. Polyacrylamides form a class of compounds varying widely in composition and activity. Separan 2610, one of the first of these flocculants' released to the mining industry in 1954, is described' as a high-molecular weight polymer of acrylamide with or without a copolymer material and with some replacement of amide by carboxylic groups. MECHANISM OF FLOCCULATION In practice, flocculation makes solids settle faster and filter better. But two opposing factors control it. The random motion that causes particles to collide favors Van der Waals' forces, which hold the particles together. The effect of zeta potential opposes this contact, and particles are mutually repelled. Flocculation can be achieved by reducing the magnitude of the zeta potential; this is the mechanism of flocculation by lime addition. The way in which polyacrylamides accomplish flocculation is not fully understood, but the action is undoubtedly comp1ex and probably varies considerably depending on the system. To begin with, the active groups of these compounds have an extremely high affinity for solid surfaces, probably by hydrogen bonding." Initially some active groups of the molecule attach themselves to the solids with a large portion of the molecule extending into the solution. Two particles can become tied together by long flocculant molecules in the following ways—by bonding between the active groups of two flocculant molecules on different particles, or by an extended molecule from one particle attaching itself directly to the surface of the other particles." These flocculant bridges prevent the particles from moving apart through random motion, but when such motion moves them together other active groups on the flocculant bridge bond to the solids, holding them in the closer position. This process is repeated until the particles are close together. Although bridging is probably a major flocculation mechanism, it is not the only phenomenon involved. Relatively neutral acrylamide flocculants reduce the magnitude of the zeta potential by increasing the viscosity of solution in the immediate vicinity of the solid surface which contains the mobile counter ions of the double layer. In other words, it moves the shear surface which bounds the zeta potential out into the solution containing counter ions which tend to neutralize the zeta potential. This effect is probably more pronounced during the initial adsorption period, before the flocculant molecules are pulled close to the solid. In some cases the slight charge of the polyacry-lamide molecule tends to neutralize a zeta potential. However, this is not a primary flocculation mechanism, as evidenced by the fact that the polyacrylamides will flocculate solids with either positive or negative zeta potential. Adsorption of polyacrylamide flocculants by a solid is substantially an irreversible reaction. Since the flocculant molecule is attached to the particle surface by many active groups of high bonding strength, desorption would require the simultaneous breaking of many bonds—an unlikely occurrence. UNIQUE PROPERTIES The irreversible adsorption of certain polyacrylamides, the flocculant's high affinity for solid surfaces and its rapid adsorption make it effective, but these unique properties require special techniques to achieve maximum flocculation. If flocculants of this type are added to a pulp as a relatively concentrated solution, the solids in the

Jan 1, 1960

By M. G. Wallis

This report presents the results of a study to develop a detailed mining method design based on longwall mining with sublevel caving. The method is applicable to low-dipping coal seams 20 or more feet thick such as are found in the western United States. The report covers (1) the development and description of the mining method, (2) evaluation of the engineering feasibility of the design, (3) estimates of productivity and recovery, and (4) an engineering cost analysis and economic feasibility evaluation of the mining method design.

Jan 1, 1977

By B. Willit, J. Martin

"Continued emphasis on water and energy conservation with less operator attention has created a need for more sophisticated cooling tower controls. A joint Betz/ASARCO project has produced a computerized water parameter controller and automated pumpless feed unit. Interfacing the unit via radio modem to the operator control room computer allows real time system status monitoring. Incorporating SPC principles to monitor and regulate all pertinent parameters yielded enhanced water control. This paper described the system design and present the results of a six month trial.BackgroundReducing operating costs and better manpower utilization are two of the largest concerns confronting maintenance managers today. At the ASARCO plant in Amarillo, a trial has been initiated to prove that it is possible to accomplish both of these objectives by using automated cooling tower control. The system is being adapted from a unit that was designed for continuously operating cooling towers in refineries and power plants by Betz Equipment Systems Division, a subsidiary of Betz Laboratories, Inc. The System l3000™ is designed to continually monitor conditions in the cooling system and to provide adjustments to the chemical balance for corrosion and deposition control. At Asarco, the unit was installed on the Rodline cooling system which operates on an intermittent basis.The primary justification for this project is to reduce costs of the five cooling systems in the plant. Current procedures require an operator to make visual checks every two hours on the five cooling towers as well as run lab tests on the water to insure proper treatment levels. This manpower can be better utilized by controlling the towers and collecting all the data available at one central location, in this case, the boiler house."

Jan 1, 1989

By F. W. Glaser

Iron-silicon alloys have had a great influence, in many ways, in modern industry. Silicon steels have been used almost exclusively for the construction of electrical machinery, but have also become an important material for structures which benefit by the high tensile and yield strengths of this material. In elaborating on the early history of work done on iron-silicon alloys, Greiner, Marsh and Stoughton1 went back as far as 1808, and pointed to Berzelius as the first producer of ferrosilicon. During the last twenty years some very important contributions in the form of studies of the iron-silicon system, as well as of the physical properties of these alloys, have been published. In consideration of the brit-tleness and poor machinability of alloys containing more than 5-6 pct Si, commercial interests have stimulated the research done on iron-silicon alloys, but mainly in the range of 0 to 6 pct Si. Yensen2 has shown the influence of im- purities, such as carbon, sulphur and phosphorus on the magnetic properties of 2, 4, and 6 pct Si alloys. Corson3 extended his investigation of physical properties to approximately 32 pct Si, and attributed the brittleness of the high-silicon material to the particular constitutional features of the alloys. Though mentioned earlier in the literature, the effect of nitrogen on crystal growth and magnetic permeability of iron-silicon alloys has been demonstrated recently by Morrill4 and Rostoker,5 respectively. In all the above quoted investigations, except that of Rostoker,5 sand or chill casting processes were employed for the preparation of samples. A major advantage of the powder metallurgy process is that it does away with time-consuming machining in many applications. The powder metal industry is always interested in pro- ducing a finished product employing a material which has presented considerably greater difficulties in manufacture by other methods. Steinit26 described preparation and testing of various Fe-Si alloys which were produced by the powder metallurgy process for the manufacture of armatures for small electric motors or generators. While Steinitz investigated alloys up to 6 pct Si, Rostoker5 went as high as 9 pct Si. The author7 previously discussed the diffusion of iron-silicon compacts containing 6 and 10 pct silicon. It is the object of this paper to study the progress of diffusion occurring in iron-silicon alloys by electrical resistivity measurements. All samples were prepared by pressing and sintering of compacts. Iron, silicon, and Fe-Si powders of various mesh size and compositions were employed to obtain test samples. It was assumed that complete diffusion had been obtained when the electrical resistivity reached a constant value characteristic for that particular alloy. To this end, electrical resistance measurements were used to follow the progress of alloying under various conditions.

Jan 1, 1950

By R. L. McCarron, G. R. Belton

The diffusivities of oxygen and sulfur in liquid iron have heen determined hy a capillary technique in which the surface concentrations of the solutes were established by means of appropriate H2/H2 and H2S/H, gas mixtures. Total diffusate and concentration profile results are shown to be in good accord, yielding for- 1560 and Supporting results at 1660°C are also presented. The conditions necessary to avoid gas transport control in this type of experiment are discussed. IN spite of their importance in understanding the kinetics and mechanisms of refining reactions, the dif-fusivities of oxygen and sulfur in liquid iron are not well established. Accordingly, as a first step in studies of rates of solute absorption from the gas phase into liquid iron, new measurements of these diffusivities have been made and are presented in this paper. The only published results for the diffusion of sulfur in pure liquid iron are those of Kawai.' He used a diffusion couple technique in which two cylindrical specimens, one containing sulfur and the other with negligible sulfur concentration, were joined together and held in a refractory capillary. After an experiment, the sample was quenched and the concentration distribution of the solute determined. Kawai recognized that significant changes in solute distribution occurred during melting and freezing and he attempted to correct the concentration profiles for these effects to give a sulfur diffusivity of 4.6 x 10-6 sq cm per sec at 1560°C. The method of correction, however, was not rigorous and the uncertainty in this result cannot be easily assessed. Koslov et a1.2 have reported the diffusivity of oxygen in iron as 7.8 x 10"3 sq cm per sec at 1660°C. This value appears to be unreasonably high but, unfortunately, details of their experiments are not available. Shurygin and Kryuk have used the rotating disc method for a study of oxygen diffusion in liquid iron. In their experiments a silica disc was rotated in liquid iron containing oxygen, and the rate of formation of liquid iron silicate was determined by measuring the decrease in weight of the disc. On the assumption that the rate of dissolution was controlled by the diffusion of oxygen in the iron, the diffusion coefficient was computed to be 5.2 x sq cm per sec at 1550°C. However, the Levich equation, which was used to interpret the rate data, was originally de- rived for the case of mass transfer between a solid disc and a single-phase liquid. The hydrodynamic and diffusion boundary layers in the iron stirred by a disc, via coupling of the silicate melt, may be appreciably different from those predicted by Levich's equations. Recently, Novokhatskiy and Ershov, using an identical experimental method to that of Shurygin and Kryuk, obtained a diffusivity for oxygen in liquid iron of 1.22 x 104 sq cm per sec at 1550°C: no reasons were offered for the disagreement. Schwerdtfeger5 has also recently studied the diffusivity of oxygen in liquid iron. He reacted shallow melts of liquid iron, 0.5 to 1.0 cm deep and contained in high-purity alumina crucibles, with appropriate H20-HZ-He mixtures. The total sample was analyzed, without sectioning, to obtain the average concentration of diffusate. A value at 1610°C of D = 12(3) x 10-5 sq cm per sec was obtained from the results of twenty experiments.= Oxygen profile measurements, which were carried out in three additional experiments using long capillaries and the semiinfinite boundary conditions, indicated a diffusivity about half that computed from the shallow bath experiments. Possible sources of error in Schwerdtfeger's study will be discussed later in this paper. EXPERIMENTAL TECHNIQUE The essential arrangement of the diffusion cell is shown in Fig. 1. The liquid iron was contained in an alumina capillary, 3 to 4 mm diam and 3 to 9 cm long, which was supported by a hollow alumina pedestal and this whole assembly was held within a movable alumina reaction tube. This tube, which was about 7 mm in bore

Jan 1, 1970

By AIME AIME

SIR HENRY CORT HAROLD CARPENTER, F. R. S. professor of metallurgy at the Royal School of Mines, was presented with his Honorary Membership certificate in the A.I.M.E. on Oct. 18, at a luncheon in his honor in the Abraham Lincoln room of the Savoy Hotel in London. The presentation luncheon was attended by some thirty distinguished representatives of the academic and industrial British metallurgical world, all friends and acquaintances of Sir Harold. Frank W. Harbord and

Jan 1, 1938

By Gabriel Gonçalves Pessoa de Castro

O trabalho teve por objetivo produzir uma liga Al AA1070 com microestrutura ultrafina via prensagem por canais equiangulares. O processo empregou a rota C com 2 passes consecutivos a frio e acumulou uma deformação ?2 = 2,38. O material de partida é proveniente de um processo de laminação a quente na qual a microestrutura resultante era composta de grãos grosseiros com tamanho de grão de 14,5 ± 19,1 ?m e dureza de 31,1 ± 1,9 Vickers. Foi realizada a caracterização microestrutural com o auxílio das técnicas de microscopia eletrônica de varredura (MEV) e de difração de elétrons retroespalhados. O comportamento mecânico das amostras foi avaliado por ensaios de dureza Vickers, a fim de se determinar a energia armazenada durante os passes. Os resultados obtidos mostraram que o material de partida apresentou estrutura parcialmente recristalizada, decorrente do processo termomecânico de laminação. A deformação cisalhante severa que ocorre na interseção entre os canais durante o processamento via ECAP permitiu um intenso refinamento de grãos. O tamanho de grão após o 2° passe foi da ordem de 1,6 ± 1,7 µm. A dureza após o 1° passe quase dobrou em relação ao material de partida, mas praticamente se manteve no passe seguinte, sugerindo uma possível estabilidade. Pode-se concluir que ocorreu um considerável refinamento do tamanho de grão em função da elevada fragmentação e rotação da subestrutura após os passes de deformação.

Aug 8, 2018

By S. J. Matas, R. F. Hehemann, R. H. Goodenow

The hot-stage metallographic method has been employed to determine radial growth rates of upper and lower bainite. Lower bainite appears to grow as individual plates that increase in both length and thickness while upper bainite grows as sheaves of closely spaced plates or needles. A discontinuity in the temperature dependence of the growth rate appears to be associated with the transition from upper to lower bainite and stepped quenching experiments suggest that lower bainite will not continue to grow when the temperature is raised to the upper range. Thus, a single process does not appear to control the growth of both upper and lower bainite. A tentative model based on the forces acting on a dislocation interface is proposed to account for the slow growth of bainite. It has been recognized since the early studies of Davenport and Bain that a close relationship exists between the martensite and bainite transformations in steels. However, diffusion of carbon during the transformation has lead to considerable controversy concerning the reaction mechanism.1-7 Many studies4,5,7-9 have emphasized the structura and kinetic aspects of the bainite reaction and, in particular, the difference observed between the two forms of bainite—frequently termed upper and lower bainite. A kinetic difference between the two types of bainite has been revealed in the activation energy determined from the overall reaction;4,5 however, many difficulties arise in an interpretation of these activation energies since a number of temperature dependent factors contribute to the kinetics of the overall reaction. The displacive surface relief10 accompanying the bainite reaction permits a separation of the nuclea-tion and growth contributions to the reaction and allows the kinetics of the growth process to be examined. Several investigations of this type have been conducted; however, they have been restricted to the low temperature range.3'6'11 Here, bainite plates are observed to grow slowly in both length and width. The present investigation extends such studies to include the upper bainite range. MATERIALS AND PROCEDURE Materials. The composition of the steels studied in this investigation are presented in Table I. The range of composition permitted a study of the effect of carbon content on the growth rate of upper bainite in the 9 pct Ni steels and consideration of both upper and lower bainite in the higher carbon steels. These steels were received as hot-rolled rounds and were forged to approximately 1/2 in. thick plates for preparation of metallographic specimens. In order to produce an essentially zero carbon steel, Steel A was decarburized in wet hydrogen at 1550°F for 15 days with the result tabulated as Steel AD. Experimental Procedure. In order to study the slow growth of the displacive transformation product, a commercially available Leitz hot stage was modified to permit heating of the specimen by its own resistance in a manner similar to that employed by other investigators.6 The furnace chamber was maintained at a pressure of 2 to 3 X 10-5 mm Hg prior to austenitizing at 2000° ± 12° F for 5 min. Samples could be cooled from the austenitizing to the transformation temperature in approximately 15 sec and the progress of transformation was recorded with a 9 cm by 12 cm single frame camera or a 16 mm movie camera. RESULTS AND DISCUSSION Growth Characteristics. The general growth characteristics observed in this investigation were analogous to those reported previously.3,6,11 Typical growth sequences for the high temperature and low temperature forms are illustrated in Figs. 1 to 5. In both temperature ranges, bainite plates increase in length at slow, temperature dependent rates until interrupted by a grain boundary, another plate, or

Jan 1, 1963

By L. J. Froisland

Water classification and heavy-media sink-float methods were investigated for concentrating metallic junk automobile shredder rejects initially upgraded to about 75-percent metal content in an air elutriation system. An 8-inch-diameter water elutriation column with a feed capacity of 2.7 tons per hour was constructed and operated. The results obtained were compared with those produced by sink-float methods. Tests made on duplicate samples of an intermediate-grade metal product were successful in upgrading the metal con-tent from 75 percent to 98.7 and 99.1 percent with respective recoveries of 95.5 and 98.9 percent for the water classification and sink-float procedures. Tentative flowsheets for treating junk auto shredder rejects are outlined.

Jan 1, 1972

Copper was first produced in Australia in 1844, at the Kapunda Mine in South Australia, and, by 18i>0, production exceeded 2,000 tons of copper a year. Output increased ,steadily, reaching a peak of 14,00Qo tons a year in 1867 and 1868, when the Burra Burra and Kapunda Mines in South Australia and the Peak Downs Moine at Clermont, Queensland, were at the height of their production. At this period, Australian copper formed a considerable percentage of the world's supply, its output equalling, for a short time, that of the United States. Production declined to between 3,000 and 4,000 tons a year after the closing of' these three mines between 18717 and 1879, and, at this stage, the Australian output came chiefly from the Wallatoo and Moonta mines in South Australia. About 19000, it began to rise again, with the extension of the railway to the copper fields of Chillagoe and Cloncurry, and, between 1905 and 1912, was at its greatest, with a maximum of 47,774 tons of copper in 1912. During this period, Australia contributed 4,7 per cent. of the world's annual production, and ranked among the six major copper-producing countries of the world (Table 1).

Jan 1, 1943

By D. J. Freeh, W. E. Horst, R. C. Kellner

This paper is concerned with the description of grinding characteristics in a batch grinding system. A mathematical model was developed and used for simulating the system on an analog computer. A general equation describing the change of selected size fractions with respect to time is presented. The empirical verification of the model is discussed. In order to understand the performance of a grinding system, it would be desirable to have a mathematical description of the system's behavior. The development of a mathematical model to describe the performance of a batch dry-grinding operation was investigated. This is the first step toward reaching the objective of a practical mathematical description of a grinding system that could be employed for process control and optimization of a simple or complex grinding circuit. Although this article is concerned only with batch grinding performance, experimental work is being conducted to extend the model to continuous grinding systems. BASIC PROCESS CONSIDERATIONS In a paper dealing with the probability theory of wet ball milling, Roberts1 correlated the rate of change of oversize material, C, with energy input, E, as follows where the energy input is expressed in power/unit mass and k is a constant for each particle size. Experimental grinding studies were made by Bowdish2 to extend the previous work of Roberts. The work of Bowdish also showed that the rate of breaking of oversize particles in a ball mill is proportional to the concentration of oversize particles present. He further demonstrated that breaking of oversize particles is proportional to the surface area of the balls used for grinding. Rate equations were presented and it was concluded that grinding could be considered as a first order phenomenon according to the rate equation [2] di which is in accordance with Eq. 1. In Eq. 2, the effect of ball area is included in the constant k,. Other rate equations were reported to show the effect of a change in ball area and removal of fines during grinding. Correlation studies made by Arbiter and BhranY indicate a first-order rate equation for quartz; however, their data showed less than first-order rates existed for some of the other materials evaluated. More recently Kelsall4 has shown that the rate of breakage of any narrow size range of quartz could be described by a first-order rate equation. Several other investigators5-7 have described grinding behavior in terms of rate equations or kinetics. In general, the rate equations have been described for each particle size; however, the interactions between sizes and the overall relationships that exist have not been considered, at least not in the form of solving a group of simultaneous differential equations. Extensive work has been conducted by various investigators using a probabilistic approach which has expanded stein's' earlier work. Selection and breakage matrices are incorporated in the probabilistic model as contrasted with the deterministic method presented here. A batch grinding operation may be considered as an unsteady-state process from the standpoint that the conditions within the mill are a function of time. Therefore, a plot of mass fraction of the i-th size versus time would give a set of curves as shown in Fig. 1. In these curves X , represents the mass fraction of large size material, X2 intermediate size, and X3 small size material. An examination of these curves shows a strong similarity to the curves that would be obtained from a chemical reaction of the type9 A?B?C, [3] where A would be comparable to the largest size material being broken to an intermediate size, 3, and

Jan 1, 1968

By W. H. Eddy

The Bureau of Mines conducted laboratory batch and continuous flotation processing tests on waste granite fines from South Carolina to determine the possibility of recovering high-quality feldspar and glass sand. Three flotation systems were used for removal of the iron-bearing biotite: Two employed an alkaline anionic-cationic circuit and the third employed an acid cationic circuit. Commercial-grade products were obtained when the remaining biotite was magnetically removed from the feldspar and quartz concentrates. Continuous flotation processing yielded a feldspar concentrate containing, in percent, 3.60 Na20, 5.60 K20, and 2.25 Ca0, with recoveries of 75.3, 66.6, and 72.6 percent, respectively. The feldspar tailing was high quality glass sand containing 98.0 percent Si02 and 0.025 percent Fe203; about 60 percent of the quartz was recovered.

Jan 1, 1972

By S Basu, P M. Midhun

Electro-Slag Remelting (ESR) is a process capable of producing ingots with much lower centre-line segregation and better internal soundness than conventional ingot casting processes, as well as lower inclusion and sulfur concentrations. This process is commonly used for alloyed steels intended for critical applications like components of marine turbines, supercritical powerplants and rocket motor casings. It involves melting a metal electrode using electrical resistive heating in a slag pool and re-solidification of the resulting metal droplets beneath the slag layer, forming an ingot. Conventional ESR fluxes consist primarily of CaF2, Al2O3 and CaO, along with minor concentrations of SiO2, MgO etc. The emission of fluoride vapour from the molten slag causes several environmental and health problems, triggering a need to develop and reduce the fluoride content in the ESR flux. The present study aims to develop low-CaF2 alternatives to commercial ESR fluxes without compromising on productivity and the surface quality of the refined ingot. Thus, the modification in chemical composition needs to satisfy properties like electrical resistivity, viscosity and liquidus temperature, essential for efficient ESR operation. Since electrical resistivity and viscosity are highly dependent on the ionic structure of the molten slag, it is important to understand the effect of compositional modification on the structure of the flux. The present study employs Fourier-transform infrared spectroscopy (FT-IR) and Raman spectroscopy to investigate the structural variations in the modified fluxes, especially the effect of changing SiO2 concentration, in comparison with conventional CaF2-rich fluxes. Additionally, thermal analysis (Differential Thermal Analysis (DTA) and Thermogravimetric Analysis (TGA)) has been carried out to characterise the melting behaviour of the fluxes. The findings are compared with simulations carried out using the FactSage™ software, ver 8.3 (GTT Technologies, Aachen, Germany). Simultaneous analysis of liquidus temperature and the structure is expected to help in identifying the practical suitability of modified ESR flux compositions for industrial implementation.

Jun 19, 2024