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By Harold L. Lovell

The current interest in sulfur recovery from coal measures is indicated by a recent report prepared for the Public Health Service (1) It was noted that the concentration of pyrites to a product containing 42-48 percent sulfur should be relatively easy with present equipment. It was also pointed out that a utility potential exists for the high-grade iron concentrate which results as a by-product of the consumption of pyrites in the acid-making process. However, economics, marketing characteristics, location, transportation, pyrite levels and coal characteristics all strongly influence the feasibility of fostering industrial development of such processes. The extent of pyrite recovery and product quality is intimately related to pyrite particle size and its degree of liberation, a consideration usually given greater emphasis in metal ore preparation than in processing coals. Consequently, fine crushing to nearly 20 mesh probably will be essential for maximum practical processing. It appears that any process separating pyrites from a coal must involve a reprocessing of the normal preparation plant refuse, although some yields can be attained from certain existing operations as products from, a shaking table or a jig. Further, the existence of millions of tons of coal refuse cannot be ignored as a mined source of raw materials. The recovery of saleable products from such wastes, although untried on a large scale under current conditions, not only offers a realistic source of sulfur but also would achieve a secondary refuse with the minimal contents of substances which incite and propagate the burning of organic and inorganic combustibles. These silicate materials, thus beneficiated, also offer some potential for economic utilization. Some significant tonnages of pyrites have been produced from coal measures in the past, but the experience was, in general, not consistent with current coal preparation practice. The processes involved did not include cyclones and heavy media; nor were they carries out under the sociological environment concerned with pollution as exists today.

Jan 1, 1967

By D. G. Cerigo

"INTRODUCTIONAn interim report covering an uncompleted project on revenue mill optimization was presented at the invitation of Mr. C.S. Stevens, the Secretary of the Canadian Gold Metallurgists. The work described summarizes the preliminary work carried out at the Noranda Research Centre on computer mill optimization and is an attempt to arrive at a model of a circuit using the ""black box"" approach and hence by using economic factors related to concentrate dollar value to maximize revenue. The help and cooperation of Mr. J.D. Wild, Mr. M.J.S. Bennett of Noranda and Dr. A. Bobkowicz of McGill University is gratefully acknowledged.DERIVATION OF MODELHistorical data from the Normetal mill were used for the study. Normetal ore contains chalcopyrite, sphalerite, gold, silver, pyrite and pyrrhotite. For simplicity, data were chosen for days when only two concentrates had been derived, a copper concentrate which also contains the gold and silver, and a zinc concentrate. In these periods when pyrite concentrate was not produced, its circuit was used as an extra zinc scavenger unit. Figure I is a schematic drawing of the circuit and Table I explains the nomenclature.The mill had been operated to obtain a fixed grade of copper and zinc in the copper and zinc concentrates respectively, at the same time insuring acceptable recovery levels. The target grade for the copper and zinc concentrates had been derived by manual calculations based on past experience. The data used were 170 sets of daily mill reports, a sample of which is shown in Table II. The data consist of daily tonnages of feed, concentrates and tailings and their average compositions obtained by taking samples every twenty minutes from each stream and analyzing the daily composite samples."

Jan 1, 1967

By D. C. Seidel

The role of surface charge in soluble salt flotation, which was developed in Part 1, is extended to relate the theory to the specific phenomena of KCI- NaCl separations. Temperature-collector solubility relationships, metal ion activation, and particle size effects are discussed.

Jan 1, 1967

By R. R. Young

Good afternoon gentlemen. It is always a pleasure to talk about a subject dear to our hearts--the high speed transfer of bull; materials. Specifically, today we will be reviewing the engineering approach to an age old problem of ship loading and unloading. You may be puzzled by the title of this paper and we will attempt to explain this for you--particularly the use of the words "New Era", since high speed automated facilities are nothing new to the material handling engineer. The new era in material handling designs refers to an all out concerted effort to provide custom engineering tailored to specific operations and economic requirements of the client. It shuns hardware type of engineering wherein existing machines and devices are dusted off and reapplied. It provides automation when automation can be justified and it exemplifies the application of systems engineering to solve specific problems.

Jan 1, 1967

By P. O. Parfitt

At the McIntyre mine, there are two distinct operations: a gold mine with narrow veins, mined by cut-and-fill methods, and a copper mine with large, open, long-hole stopes. The application of the Critical Path Method to scheduling work in the copper mine, where it has been used successfully for several years, is de-scribed briefly. This application is relatively simple. Use of C.P.M. has now been extended to the gold mine. To replace the former method of scheduling from bar-charts, a procedure was developed for scheduling automatically. To handle an operation of this size and complexity, a computer was essential. Improved schedules are now being produced, with a saving in time.

Jan 1, 1967

By R. R. Godard

The practice of dust abatement or control is not new to any operation of United States Steel Corporation. This report will review those activities, past and present, within the five operating districts of United States Steel-Coal Operations with specific reference to mechanical and continuous mining, and including both the health and safety aspects of the problem. Obviously, the first principle of dust control is to inhibit its formation If this is not practical, steps may be taken to prevent its becoming airborne. Airborne dust control can be realized by either collecting it at the point of generation, diluting it with large volumes of air to reduce concentration, settling it by various means, or with reference to ignition hazard only, render it incombustible by neutralization with an inert material. These basic principles have been verified by the work of many, including the Bureau of Mines, U. S. Department of Interior, Bituminous Coal Research, Inc., and the Mining Research Establishment of the National Coal Board of Great Britain. Their application to every day mining problems is best illustrated by the following examples.

Jan 1, 1967

By F. Haessner, M. Wilkens, U. Jakubowski

ThOUGH at present there is a wide range of possibilities for the quantitative determination of preferred orientations, pole figures of identical specimen material have not been determined by different methods as yet.''' In this paper a comparison of (Ill), (200), and (220) pole figures is presented which were obtained from a 95 pct cold-rolled high-purity cop- per sheet (99.9998 pct Cu), by three different methods. The three methods are: a) The combined X-ray reflection-transmission technique of plane samples by schulz3 and Decker, Asp, and Harker. 4 A Siemens texture goniometer was used. The experimental details are described elsewhere. 6 b) The X-ray reflection technique of spherical samples by Jetter and Boric.' A Siemens texture goniometer with some modifications was used. The samples were prepared by sticking 140 polished sheets together with an adhesive and machining a sphere (20 mm diam).* Additional

Jan 1, 1967

By J. Stringer, I. W. Edington, C. R. Rarey

THE geometrical interpretation of transmission electron micrographs of hcp metals is more complicated than the equivalent interpretation of cubic metal for two reasons: firstly, prominent zone axes are not in general normal to prominent planes, so that a simple diffraction pattern often corresponds to a nonra-tional foil plane; and secondly, the Miller-Bravais sys-tem of indexing directions is not easy to visualize. In this, the indexing is referred to the Bravais four-axis system, and the direction is labeled [hkil], chosen so that and I are shown in Fig. 1. Some geometrical relationships useful for the interpretation of transmission micrographs have been calculated and are tabulated below: 6) Direction of the intersection of two planes; this is easily calculated by applying Condition 4 to both planes: a direction that lies in both planes is clearly their direction of intersection. Some of the above expressions have also recently been given by Otte and Crocker;' Expression 5 is of course in most standard crystallographic texts. It is generally considered easier and quicker to use graphical methods for the interpretation of electron micrographs than analytical methods. For this purpose, it is most convenient to use a "double stereo-gram" in which both the poles alzd the rational directions are plotted. It is, of course, necessary to orient

Jan 1, 1967

By V. B. Tare, H. Schmalzried

The use of solid electrolytes for determining kinetic paraneters at elevated tevnperatures is pointed out. The reaction rate constant k1 of the phase-boundary reaction during oxidution of iron to wiistite by CO2-CO gas mixtures has been deternined between 850 nnd 975C, using ZrOz(+CaO) as an electrolyte. Values are between 1.4 x 10-a and 5.2 x 10 ole per sq ctn atm. The tzain difficulty is due to mixed potentials arising from side reactions at the electrolyte inteyface. In a number of papers the calcium-doped zirconia electrolyte has been used for the determination of thermodynamic data from measured differences in oxygen activities (or potentials) between two electrodes. The purpose of this note is to suggest the use of this solid electrolyte for kinetic measurements as well. The principle can be seen from Fig. 1. A thin and compact phase II (electron conductor) is fixed on a plate of gas-tight, polished ZrO2(+CaO) (I), which separates two compartments with different oxygen potential. p, is a constant reference pressure of oxygen (1 atm). The electromotive force of this galvanic cell is given by E = RT5 In pep, and pe is the oxygen partial pressure at the interface electrolytephase 11. If phase I1 is in equilibrium with the surrounding gas phase, p, = DR. If pg changes sud- denly to a value pi, p, and therefore the electromotive force, E, change as a function of time according to the phase-boundary reaction rate at the gas phase I1 interface and the transport processes inside phase 11. It is assumed that local equilibrium is established at the boundary electrolytephase 11, that the gas phase shows no concentration gradients, and that the con-

Jan 1, 1967

By J. S. Coffman

Wyoming is estimated to have more than 700 million tons and Utah more than 2.5 billion tons of +10 percent P2O6 phosphate rock considered to have some future economic potential. In Wyoming, the +24 and +18 percent P205 rock potential resources total nearly 250 and 450 million tons, respectively. In Utah, the +31, +24, and +18 percent rock total approximately 33 million, 222 million, and 2.2 billion tons, respectively. These resources are all located above the local drainage levels and do not include latent resources. All of the mining and beneficiation of phosphate rock in the two States is done by San Francisco Chemical Co. The facilities include open pit mines at Vernal, Utah, and Leefe, Wyo.; an underground mine in the Crawford Mountains, Utah, and beneficiation plants at Leefe and Vernal. One of the principal markets for the phosphate rock is Western Phosphates, Inc., fertilizer plant at Garfield, Utah. Recent exploration and development has been under-taken by different companies in the Southeastern Wind River Range, Sublette Range, and Crawford Mountains. The facilities at Leefe and Vernal are in the process of expansion. Some of the areas of western Wyoming contain vast quantities of phosphate rock in minable units, but, because of their remote location, are classed as latent areas. In these areas, there are estimated to be about 700 million, 2 billion, and 3 billion tons of phosphate rock in the +24, +18, and +10 percent P205 grade classes, respectively. The Snake River Range of Idaho and Wyoming is also estimated to contain roughly 21, 106, 177, and 214 million tons of potential resources in the +31, +24, +18, and +10 grade categories, respectively. This area also contains a large amount of latent rock in the more remote areas.

Jan 1, 1967

By Ronald P. Hollenbeck

The value of mineral production in Alabama increased 1 percent above the record high set in 1965. Alabama ranked second among the States in the production of bauxite, third in the production of masonry cement, native asphalt, and scrap mica, sixth in the production of portland cement, ninth in the production of iron ore, and tenth in the production of lime. The mineral industry of Alabama was dominated by the mining and processing of coal and stone, the manufacturing of cement, and the production of crude petroleum. These industries accounted for 87 percent of the State's total value of mineral production, compared with 85 percent in 1965.

Jan 1, 1967

By S. W. Mao

Hydrologic and economic criteria figure in many obvious ways in water resources development, but they are rarely linked quantitatively, and most of the applications are pertinent only to the case-in-point. In the preparation of the Regional Plan for the massive program of ground water development in the Punjab, situations have arisen where the choice among two or more alternatives was made by analyzing the economic implications of critical hydrologic parameters. Two of these situations which are of more-or-less general interest are described herein. The first involves basic development policy -- whether ground water development should be based on the demand of the economy, or the conservation concept of safe-yield. The analysis demonstrated that mining of ground water is clearly indicated for areas where alternative supplies are unavailable. The second problem involves integrating hydrologic data into an economic model to determine optimum well design, From an analysis of all pertinent factors, a simple nomograph was derived which can be used to determine well specifications on-site during construction. The nomograph can be modified for use in any alluvial terrain.

Jan 1, 1967

By Forrest T. Moyer

The overall disabling work injury experience, excluding office- workers, at nometal mines and mills during the period 1961-63, as reported to the Bureau of Mines by operators, was 77 fatal and 7,201 nonfatal injuries during an aggregate worktime of 335,029,685 man- hours. These injuries, fatal and nonfatal combined, occurred at a frequency rate of 21.72 per million man-hours, comprising 0.23 for the fatal and 21.49 for the nonfatal injuries. The combined severity rate of the disabilities was 2,312 days lost or charged per million man-hours, consisting of 1,379 for the fatal and 933 of the nonfatal injuries, The average severity of all disabilities during 1961-63, was 106 days per injury, The number of days lost or charged, excluding officeworkers, at nonmetal mines and mills during 1961-63, was 462,000 days charged to fatal injuries and 312,461 days lost from nonfatal injuries. The outstanding causes for fatal injuries were explosions (18 fatalities occurred in a major mine-explosion disaster in a potash mine in Utah in 1963) and falls of rock or ore from back or side, while most nonfatal injuries were caused by handling materials, slips or falls of persons, haulage, and machinery. The parts of the body most frequently injured during the period 1961-63 were the trunk, hand and finger, and foot and toe, An average of 52,810 men were at work daily, There were 20 nonfatal disabling injuries reported for office- workers at nonmetal mines and mills during the period 1961-63 during an aggregate worktime of 23,088,496 man-hours, These injuries occur- red at a frequency rate of 0.87 per million man-hours, There were no fatal injuries reported.

Jan 1, 1967

By F. D. Everett

This report summarizes the results of a nationwide investigation completed in 1964 to determine the nonferrous base metal ore reserves and potential sources of ore and to evaluate criteria for their ultimate exploitation. Engineers of the Bureau of Mines contacted mining company officials, reviewed reports and Government records, and where necessary made personal appraisals in arriving at the results. The estimates are presented by metals in ores in geographic regions and include some of the problems affecting the reserves and potential sources. The recoverable metal in the measured ore category and in the total ore reserves was estimated as follows: [ ] At the 1963 rate of domestic mine production these total reserves would be adequate to provide copper for 62 years, lead for 121 years, and zinc for 42 years. Data also are given for gold, silver, and other coproducts. Reserve estimates greatly exceed those of previous investigations; some prior estimates of copper reserves are included for comparison (table 23). Projections of requirements for base metals indicated the United States will need approximately 45 percent more copper in 1970 and 110 percent more by 1980 than was consumed in 1960; similar projections for lead indicate increases of 20 percent by 1970 and 45 percent by 1980; zinc projections are 40 percent more by 1970 and 90 percent by 1980. Much of the production of gold and silver is a coproduct of base metals recovery and the projected need for the precious metals exceeds all the United States can produce. Some problems of the industry are mentioned. A graphic evaluation of the economic availability of the reserve and potential sources is shown.

Jan 1, 1967

There was a time, in the memory of some here tonight, when the annual meeting of The Institute was a nostalgic occasion. Often, in the 1920s, there was comment on the decline of Australian mining and on the lack of new mineral discoveries. When some of our Presidents prayed then for a new Bendigo, and instead were given a Mount Isa, they were justifiably disappointed because of the vastly different capital requirements.In 1967 the mining picture is very different. The recent mining developments in Australia are certainly as important as several Bendigos and several Kalgoorlies. The mining industry in Australia has never been more dynamic than today (Table 1). And if we ask why it is so dynamic, the answer lies in the role which overseas capital is playing in the industry. The contribution of overseas capital should concern us not only because we are members of the mining and metallurgical profession, but also because we have a duty to make our profession contribute as much as possible to the well-being of Australians. It is not sufficient to argue that overseas capital is good for the mining industry; we must also examine whether it is good for the economy and the nation. In this context the current criticism of the inflow of overseas capital into Australian mining is useful, for it gives us an opportunity to see what has resulted from the inflow.In discussing this question I do not suggest that we emulate Captain Hancock, that legendary Moonta mine manager who, according to Oswald Pryor's cartoon, used to say to his miners: "When I say a thing is, it is, even if it isn't". The question can only be discussed on a factual basis; and I would submit that many of the important facts relating to overseas capital in our mining industry are often overlooked or ignored. I would further submit, on the basis of these facts, that Australia's present day mining industry has been largely built on overseas capital and that the overall benefits of that capital to Australia have been enormous.

Jan 1, 1967

By J. W. Wolfe

The Benedict-Webb-Rmbin equation of state was used in digital computer programs to make rapid determinations of natural gas equilibrium phase compositions. Mixture components were the nine hydrocarbons, methane through heptane. Comparative tests were made with data from field separators, plant exchangers and literature sources. For most tests made, the B-W-R equations predrcted component K-vallles, mixture enthalpies and phase aensities within tile accuracy of available correlations for rune-component mixtures: significant deviations were noted when mixtures contained components heavier than heptune. INTRODUCTION Rapid, accurate methods for calculating the properties of hydrocarbon mixtures are needed for predicting the behavior of natural gas processes. For example, because of the common use of two-phase separation methods in gas proccssing, calculations must be made for the density and composition of equilibrium vapor and liquid phases. In addition, predictions must often be made for the temperature and pressure changes associated with the flow of single- and two-phase natural gas fluids through heat exchangers, chokes and turbines. The complex nature of non-ideal mixtures makes rigorous calculations for these natural gas properties difficult and time-consuming. Natural gas properties have conventionally been determined with generalized data correlations. These correlations, such as the K-values presented in the NGAA Equilibrium Ratio Data Book, are usually based on some average property of the mixture and have proven to give satisfactory estimates for the properties of most oil and gas systems. Digital computers, however, have not only increased the utility of these correlations, but also have made practical the use of equations of state for calculating the properties of natural gases. Potentially, if basic pure component data are available, all the desired thermodynamic properties of mixtures can be derived from a single equation of state describing the mixture. Currently. the best equation of state for describing the behavior of pure, light hydrocarbons over single-and two-phase regions, both below and above critical pressure, is that of Benedict. Webb and Rubin.' The equation contains eight constants which are determined by empirically fitting the equation to pure-component PVT data. Benedict and his co-workers presented the clevelopment of their equation as early as 1940.2 The B-W-R equation is a modification of the Beattie-Bridgeman equation of state and gives better PVT predictions than the Beattie equation at densities above the critical density. Benedict et al. made the equation applicable to mixtures by relating the mixture constants to composition and the constants for pure compounds. These authors, in a serics of articles in 1951,' showed the accuracy of the B-W-R equation when applied to light hydrocarbons and their simple mixtures, and demonstrated the equation's utility for making vapor-liquid equilibria calculations. Since its inception, the B-W-R equation has been the subject of many papers. Numerous additions and modifications have been proposed,'-',"'-':' the purpose of most being to improve the equation's ability to predict PVT properties of specific mixture systems. In 1959, Opfell, Pings and Sage summarized much of the work on the B-W-R equation in their book on equations of state." Since natural gases are primarily mixtures of light hydrocarbons, the B-W-R equation is a natural choice for an equation of state to compute both phase equilibria and thermodynamic properties of natural gases. Consequent-

Jan 1, 1967

Devitrification of a glassy volcanic ash equivalent to an alkaline trachyte in composition has resulted in the formation of an interstratified illite-montmorillonite with an 1:1\1 content of 1:4 as the principal clay mineral.A high concentration of potassium ions and a deficiency of magnesium ions favoured the formation of the potassium-bentonite.A poorly ordered mica mineral, equivalent to illite, was produced by weathering of potassic feldspar. Subsequent degradation of the illite through the loss of potassium was responsible for the formation of several interstratified minerals with very approximate 1:1\1 contents of 4: I as minor components.Other authigenic minerals present in small amounts were u-cristobalite, sepiolite, and the zeolite clinopitolite.The non-swelling character of the potassium-bentonite makes it economically unattractive...

Jan 1, 1967

By Howard N. Egan

EASTERN COAL CORPORATION is located in the heart of the Appalachian Mountain area of extreme Eastern Kentucky, The mountains are of sedimentary origin, and have been deeply eroded by streams as the area has been thrust up during geologic time. There are many seams of coal interspersed between beds of shale and sandstone. While some of the seams are thin, there are a number that can be economically mined. We are mining the Pond Creek, or No. 2 Gas Seam, at a rate in excess of 6,000 tons per day. Our central preparation plant utilizes tromp baths for the plus 3/8" size and Rheolaveur for the minus 3/8" portion. No provision was made to recover the fine coal, which was included with the plant effluent pumped to a 12 acre refuse pond. The pond is impounded behind the coarse refuse dump. This pond rose 15 feet last year. Obviously, no pond could stand many years at this rate. Limited pond space in this rugged area of steep hills and narrow valleys dictated a revised disposal method. Our first thought was that it would be necessary to dry the fine refuse sufficiently to permit inclusion with the coarse refuse, which is hauled uphill by monitor and then trucked to final disposal.

Jan 1, 1967

By W. C. Ellis

Growth directions of tin, zinc, and cadmiun whisker crystals grown spontaneously fi-om the solid are summarized. In tin the edge and diagonal directions of the unit cell are jound with the exception oj- the [110] diagonal. In cadmiurn and zinc the usual dip-ections are a or a + c. The c direction has not been ohserwed. The gvouth directions from the solid are for the most part the same as those found for vapor-grozun crystals and are the ohserz:ed glide directions in plastic j-lou. Whisker crystals of these elements grown from the solid are not twinned. Specular lateral reflections are associated with planes of snall crystallographic indices. WHISKER crystals of tin, zinc, or cadmium grow spontaneously at room temperature in periods from months to years from thin electroplates and other prepared films of the respective metals.''2 It has been established that these crystals are single, but the question of twinning, such as occurs in whisker crystals of silicon,3'4 has not been resolved. Studies of morphology have been restricted to determinations of growth directions.5-' Whisker crystals are both straight and kinked. A few studies have been made on kinked whiskers including measurements of kink anglesa and determinations of growth directions,' but unfortunately not both on the same crystals. The kink angles, for the most part, for each species are grouped closely about a few unique values, but these values are not always those between observed growth directions in a single crystal. To supplement existing data, the growth directions, identification of lateral features, and presence or absence of twinning were determined with a Weissenberg goniometer by a method described elsewhereg on eight whisker crystals of tin, five of zinc, and five of cadmium. One kinked cadmium whisker was examined in detail. The specimens were needlelike, a few microns in cross section, and of the order of a millimeter in length. They were removed from electroplated substrates on laboratory specimens and commercial equipment after several years of growth as described in Table I. Since the specimens were less than 10 p in cross section they were ideally strong with no attendant risk of plastic deformation or damage in handling. Only deformation twinning has been reported for these elements. Therefore, twinning probably should not be expected in whisker crystals of these metals, particularly a twin plane containing the growth direction. A twin plane oriented in this direction was the one sought in this study. No examination was made for twinning at the boundary between kink segments except for one cadmium crystal. Well-defined reflections occur as a whisker crystal of tin, zinc, or cadmium is rotated about its growth direction when illuminated by a beam of light Although these reflections had been noted in earlier investigations, no study of them was made, probably because the earlier studies had disclosed also that

Jan 1, 1967

By G. S. Cole, G. F. Bolling

ThE exact type of fluid flow which occurs in a solidifying ingot is important in determining subsequent grain structure. This has been shown in studies of natural Convection" and of forced stirring or other disturbances of the melt."16 We shall explicitly argue that a complement to the existing natural flow in an ingot should be more effective than other types of flow in promoting the columnar-to-equiaxed transition. The ultimate effects of fluid flow upon structure is one of the topics of solidification that we have investigated in the alloy system Pb-Sb, under conditions simulating casting. In Fig. 1, the essential features of a bidirectional growth apparatus are shown; horizontal freezing from water-cooled faces within a low-thermal-conductivity lavite boat is a reasonable simulation of an ingot section. Details such as the furnace and thermocouples are omitted in order to show the location of four permanent. magnets, each with a pole separation of 21 in. providing a central field of about 1000 Gauss. When coupled with a dc current imposed through appropriate connections made at the cooled faces, a flow of fluid is produced as shown schematically. This technique described by Pfann and ~orsi" is ideal for our purpose since the flow indicated is the same as that we observe to occur naturally in this system. Components of 99.999 pct purity were used for study and all due precautions were taken in alloy preparation to avoid contaminants. Sections of the specimens were taken to ensure results representative of the interior as well as the surface of specimens. All proportions of equiaxed and columnar regions were measured by tracing the etched grain structures onto graph paper and simply counting squares. Four alloys were examined at superheats of 40" * 5°C and 100" * 9°C. Preliminary tests had shown that no appreciable enhancement of structure was obtained with magnetic field alone, so that this condition is not reported; it should nevertheless be noted that other configurations of magnetic field will reduce convection and thus enhance columnar growth.'8 For the tests reported the magnetic field was applied to a specimen by bringing the four preassembled magnets to a position 2 mm from an outer tube immediately after the ingot was poured. The dc current of 30 amps passed through the sample throughout the entire solidification cycle, resulting in a power dissipation of 9 w per sq cm of interface. This may be compared to the evolution of latent heat of approximately 18 w per sq cm. Table I contains the results of this experiment in terms of the total area ratio, equiaxed/columnar grains, as a function of the field interactions, solute concentrations, and superheats employed. The total structure of the ingot is seen to be most influenced when both the field and current are applied simultaneously; when current acts separately, little effect may be noted in spite of the heat supplied. In addition, the change in structure from the no field-no current case to the field-current condition is more pronounced at the higher superheat, and the higher the concentration of antimony. An example of the grain refinement, as well as the increased equiaxed zone, is shown in Fig. 2. It is now important to prove that there is indeed an increase in fluid flow due to the presence of the field-current interaction; this is done by temperature measurements in the liquid metal. Let us consider a bidirectional casting in which heat is applied to and removed from the system, in such a way that rate of solidification is zero.* When a sensitive thermocouple

Jan 1, 1967