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By C. F. Allen, G. B. Walker

The sink-float methods designated by heavy-media separation processes were pioneered by C. Erb Weunsch for the treatment of base metal ores as an improvement over jigs. The work of Weunsch was further developed by Victor Rakowsky and The American Zinc, Lead and Smelting Co. Early in the development of the processes, the inherent unsuitability of galena as the solid constituent of the medium was recognized and ferrous media amenable to magnetic recovery and control were developed. The high efficiency and low cost of magnetic recovery and cleaning of ferrous media regardless of particle size, slime contamination, or surfacial oxidation had led to the adoption of ferrous media by all of the sink-float plants operating under the heavy-media separation processes patents controlled by American Zinc, Lead and Smelting Co. Approximately 2,000,000 tons of base metal and nonmetallic minerals are treated each month by these methods. Heavy-media separation processes are a modern practical and economical adaptation of the well-known laboratory procedure for separating a mixture of two solids by immersing the mixture in a liquid having a specific gravity intermediate the specific gravities of two solids. The lighter solid floats while the heavier sinks. This method of separation has been attempted on a commercial scale, but the high loss and high cost of the organic liquids halted the development of the process. Many attempts have been made to simulate a heavy liquid by using a suspension of a finely divided solid in water. If the solid phase of the suspension is ground fine enough, the suspension can be made stable or so slow settling that a substantially uniform specific gravity can be maintained from top to bottom of the bath. However, any material separated by such methods will inevitably be contaminated by some slime which will eventually accumulate in the bath and cause a viscous medium at the expense of separating efficiency. Therefore, it is necessary to provide means for continually cleaning a portion of the medium to eliminate slime at the same rate at which it is introduced to the medium. The problem of efficiently cleaning the medium limits the minimum grain size of the solid of the suspension in the case of the Chance sand process for cleaning coal, because de-cantation is the only cleaning method available. If the sand is too fine, it will be lost along with the slime. Therefore, coarse sand must be used, and to maintain a semblance of a uniform suspension, it is necessary to use strong rising water currents. The combination results in a separation based more on hindered settling classification than on sink-float principles. As previously mentioned, galena was used as the solid constituent of the medium during the early stages of the development work. The high specific gravity of galena made it suitable for the preparation of medium for high specific gravity separations. Galena can be cleaned by either decantation or by froth flotation. As with sand, de-cantation limits the minimum particle size of the media that can be cleaned without excessive loss. Froth flotation for cleaning galena medium has been used, but the problem of floating fine galena that has been exposed to extensive oxidation is well known to be a most difficult one. Last year the largest heavy-media plant m the world, and the second plant to be installed, converted from galena medium to ferrous medium despite the fact that the ore contains galena which can be used as medium. The change to ferrous medium has been beneficial in many ways. Today all the heavy-media plants have been converted from galena to ferrous media. Unquestionably, ferrous media have the widest application of any media developed, for the following reasons: 1. Ease of recovery and cleaning by magnetic means. Particle size or surface condition not a factor. 2. Low consumption per ton of ore treated. 3. Resistance to abrasion. 4. Widest range of media densities, including higher workable densities (1.25 to 3.4) than have been found possible with nonferrous media. 5. Space required for recovery and cleaning of ferrous media is considerably less than that for nonferrous media. 6. Ferrous media require lower capital investment and operating costs for media recovery and cleaning. Advantages of Heavy-media Separation Processes Heavy-media separation processes offer the following positive advantages, amply demonstrated on a wide variety

Jan 1, 1950

By C. H. Hitchcock

A brief resiclence in Virginia hasenabled me to examine some of its crystalline strata, and a few hints, concerning their correspondence with similar rocks elsewhere, may be of service to those who are studying them. In comparing the crystalline rocks of Virginin and New England, we may first recall the similarity of their geographical position. They constitute a continuous belt, being traceable through the Highlands of New York and yew Jersey, Southeastern Pennsylvania, in the counties of Bucks, Montgomery, Philadelphia, Delaware, and Chester, and Marylund. Thus the Green Mountains of Vermont and the White Mountains of New Hampshire seen] to be topographically continuous with the Blue Ridge and Midland districts of Virginia. This tract of country has been termed the Atlantic area in distinction from the Appalachian territory, whose eastern limit is the great, Lower Silurian limestone valley extending from the St. Lawrence and Champlain valleys to Alabama. The Appalachian formations were studied by the brothers Rogers, forty years since, and found to refit, unconformably upon the western flank of the Blue Ridge, the oldest of the series adjoining the gneisses, followed westerly by the other Palseozoic members in a regular ascending order, to which numercial designations were applied—Number 1 being the Cambrian, Number 2 the Lower Silurian Iimeqtones, etc?. In Vermont the same conclusion Was presented in the State reports: the Green Mountains were said to possess the anticlinal structure, and to underlie the quartzites and limestones. Inasmuch as this Atlantic area is' topgraphically continuous from the Middle to the Northern States, and is unconformably overlaid upon the west side by the same succession of strata, the presumption ii very strong that the history of bath sections has been the same, and that the entire area is of Eozoic age. Cross sections, in both districts, illustrate the existence of gigantic overturns, causing the strata of 'the Appalachian region to dip to wards the Atlantic gneisses. To the beginner it would appearthat tile Silurian group must dip beneath the crystallines, and hence many of the geologists in the beginning of the study of the stratigraphy of this easters border of the continent believed that

Jan 1, 1882

By Henry Hibbard

THE process of making washed metal now followed is in principle that described by Holley before this Institute in 1879, as the Krupp washing process. Sir Lowthian Bell also experimented extensively in England during 1877 and 1878 on refining iron and joined his interest with Krupp, the process being often referred to as the Bell-Krupp process. The only plant in this country now operating this process is that of the Brier Hill Steel Co., Youngstown, Ohio. This process may be considered as the sole survivor of the numerous methods conceived for refining crude iron, when the removal of phosphorus from steel-making material was the great desideratum affecting large districts. The east coast of England and all northern Germany, the homes of Bell and Krupp, respectively, could at that time make steel only from imported ores. These processes were in use or in various stages of development 40 years ago and all except the Bell-Krupp received their quietus from the development of the basic steel processes, both pneumatic and open hearth. The aim of the early refining processes was, first, the removal of the silicon; which could be clone on a sand bottom, and later, the removal of the phosphorus, requiring a bottom which would give or permit a basic slag. The incidental advantages of increased yield and small fuel consumption were not generally recognized or considered; the aim of the later. operations was the saving of the difference in value between low and high phosphorus irons, as well as hastening the removal of the metalloids. The chemistry of the washing process follows in part that of the puddling process, and indeed washing might, be considered as the first half of puddling, since all the non-ferrous elements of the crude iron, except the carbon, are eliminated and the iron is maintained molten until cast. In puddling, the iron loses its carbon as well, and because of that, its fusion point rises above the hearth temperature; it freezes into a pasty malleable form, and is worked at once by squeezer, hammer, or rolls.

Jan 12, 1915

By Charles H. Jacoby

In 1774 a Swedish chemist, C. W. Schule, first recognized manganese as an element. That same year Schule's associate, J. G. Gahn, isolated the element manganese for the first time. In 1856 the Bessemer process of steelmaking gave birth to the economic importance of manganese. Later, in 1882, Robert Hadfield discovered high manganese steels. Although the primary use of manganese is in the ferroalloy industry, two additional important uses for manganese are making chemicals and dry cell batteries. Manganese is also vital to plant and animal life. Various chemical compounds of manganese are used in fertilizers, feeds, glass manufacture, paints, varnishes, and for numerous medicinal and chemical purposes. For the study of industrial minerals and rocks, only the chemical and battery grade material is of concern, but for the sake of comparison, metallurgical aspects are included in this presentation. Although currently the world's largest consumer of manganese, the United States is producing only minor amounts of ore at the present time. This is due primarily to the fact that although huge deposits of manganese occur within our borders, all are of such low grade as to be economically unfeasible to mine. For many years various government agencies and segments of private industry have devoted sizable sums of money and time in an attempt to upgrade ores from the various deposits, and also in an attempt to recover manganese from blast furnace slags. In view of current world prices, and the quantity of high grade material available, there is little likelihood that any of these approaches will be found to be economically feasible in the near future. Geology and Mineralogy Mineralogy There are over one hundred minerals that contain manganese. These minerals vary from those with compositions that are predominantly manganese to those having only minor percentages. [ ] Geology From a geological standpoint most manga¬nese deposits are complex. In general, it can be said that all primary deposits of manganese are carbonates or silicates. The most productive and profitable have been those of sedimentary origin and residual concentrations. Examples of these residual types of deposits are associated with the metamorphosed lodes of Madhya, Pradesh, India, and the lateritic deposits of Orissa and Bihar, India; nodules in the residual clays of the Philippine Islands, U.S. southern Appalachians and Arkansas, Ghana, and Brazil. Sedimentary manganese deposits are best exemplified by the Nikopol district of Russia and the Tchiatouri area of Georgia, USSR. Hydrothermal replacements are characterized by the rhodochrosite deposits of Butte and Phillipsburg, Mont. In general, the hydrothermal type deposit has not resulted in any large tonnages being produced, but may have given

Jan 1, 1975

By Henry M. Howe

THIS paper gives the composition of the iron and slag at different stages in the "air-furnace" process of preparing "hard metal," or white cast-iron, for conversion into malleable cast-iron by annealing. The details of the process are given in an appendix. One of us had been trying for years to work some chemist of some of our malleable-iron works up to a degree of enthusiasm which would lead him to make such au investigation. It would have had the advantage of the greater familiarity with the conditions which one habitually on the spot must have. Failing in this, he made use of an opportunity which presented itself of taking samples here represented, with such fairness as the conditions permitted, holding firmly that a rough approximation to the truth is better than the complete lack of data, or that a bird in the hand is worth two in the bush. We hope that this attempt may stimulate others effectively to duplicate this work, and thus correct or confirm it. Our results are shown in Table I. and graphically in Figs. 1 and 2. Discussion.-At the time when the first two samples were taken, the metal and slag were still too sluggish to permit fair sampling, and not until sample 6 were the conditions really favorable, because at the time of the fourth sample the metal was not fully melted, and even at the time of sample 5 it was still sluggish. Indeed, the slag was probably very heterogeneous throughout, because it took up silica and alumina rapidly from the bottom, and because it was so siliceous as to be sluggish at this relatively low temperature. This hetero-geneousness is exaggerated in the two samples of slag 8, apparently by the great viscosity due to its extraordinary acidity. Note that the manganous oxide of one sample is about two and

Mar 1, 1909

By Lyon F. Terry

ACCEPTED current practice for A the valuation of mineral property is based upon Hoskold's theory and valuation tables first published in 1877, and popularized by Herbert Hoover's "Principles of Mining" issued in 1909. In more recent years the procedure has been developed further in the course of the extensive valuation work required for Federal taxation purposes. The 1-aluation of oil and gas properties and of mines is based upon the same principle-the estimation of the present worth of future net revenues. However, in valuing oil and gas properties the method used for discounting future revenues differs somewhat from that adopted for mines, owing principally to the nature of the re- source. production from oil and gas properties usually declines from year to year, whereas coal and ore de- posits are adapted to a more uniform rate of output.

Jan 1, 1940

By James C. Fowler

The use of ground-probing radar as a reflection mapping tool is gaining acceptance in subsurface investigations. This tool may be used to obtain near-surface information useful to geotechnical engineers. Along with the lightweight field equipment now available, radar is being used to obtain information that may impact the safety and production of mining, tunnelling, and excavating operations.

Jan 1, 1982

By Fordyce Coburn

RICHARD ore mine of the Colorado Fuel & Iron Corp. is an underground magnetite operation located in northern New Jersey approximately four miles northeast of the town of Dover, and 40 miles west of New York City. The mine is situated on the southeastern flank of one of the many gneissic ridges having a northeast-southwest trend

Jan 11, 1953

By R. B. Moore

Page History................................ 708 What is Radioactivity?........................ 710 Disintegration Series.......................... 711 Radium Ore Deposits......................... 713 Metallurgical Treatment........................ 717 Methods of Ore Concentration..................... 722 Future Supply of Ore......................... 723 Uses of Radium............................ 723 Mesothorium as a Substitute for Radium................. 724 Discussion.............................. 725 Probably no other metal excites as much interest, among both scientific men and the general public, as radium. This is due partly to the high cost of radium salts and partly to the peculiar properties of the element. Since radium-bearing ores were discovered in the United States, the interest of American scientific men has been stimulated and, at the present time, more radium is extracted and refined in this country than in all the rest of the world together. HISTORY The property of radioactivity was discovered, partly by accident, by Henri Becquerel, the French physicist, in 1896. He was experimenting with certain fluorescent substances in order to find, if possible, a connection between fluorescence and the recently discovered X-rays. Among other chemicals which possess the property of fluorescence, he was using salts of uranium. His custom was to expose the fluorescent substance to the action of sunlight and then register the effect of possible penetrating radiation on a photographic plate protected from ordinary light. Bec-querel's experiments gave positive results at once, and he at first believed that he had discovered a relation between fluorescence and X-rays. Later he exposed a plate to a uranium salt which had not been previously exposed to sunlight. To his surprise, on developing this plate, he found that he had obtained the same effect as he had previously secured when

Jan 1, 1919

The annual spring excursion of the College of Mines, University of Washington, is being made to the Coeur d?Alene region of northern Idaho. A party of 15 students and, instructors is visiting the Bunker Hill and Sullivan mine, mill and smelter at Kellogg, and several mines and mills in the neighborhood of Wallace and Mullan.

Jan 5, 1917

By Ralph H. Kress

Haulage trucks designed expressly for mine service were introduced about 35 years ago. The first models to arrive on the scene hauled about 15 tons and easily outperformed the modified highway trucks that had been used for mine haulage up to that time. The specialized trucks obviously had a greater potential for mining operations, and once this fact was recognized, competitive pressures in both the mining and truck-manufacturing industries drove the new vehicles toward ever more efficient performance. Many changes in truck design resulted, but not all were accepted for a variety of reasons. Often poor design was the reason, but in many cases progressive and promising designs were abandoned only because the truck manufacturer lacked the courage, tenacity, or vision to capitalize on them. There were also many cases where a promising new design was abandoned because the prototypes were initiated in a mine where personnel lacked the patience to prove them. Truck Startup Takes A Team Ally new truck that is to succeed and contribute to lower mine haulage costs must be well conceived and launched with good teamwork on the part of all concerned. Naturally, it is essential to have a good overall truck design at the outset to make this teamwork worthwhile. The design must include the selection of the right components manufactured by suppliers that can each do justice to their particular part of the new truck. Last, but by no means least, the mine operator where the truck is to be launched must be enthusiastic in his efforts to see the new vehicle through to successful operation.

Jan 1, 1971

The plan for establishing relations of American industry with national labor on a definite basis so closely follows the channels of the efforts of Engineering Council, principally in the classification and compensation work, that it is of special interest to the engineering profession. The principles laid down under the following headings are about to he submitted to a referendum vote of the membership of the Chamber of Commerce of the United States. These principles were prepared by a special committee of the Chamber of Commerce after a long period of study of the entire subject of industrial relations. 1. Industrial enterprise, as a source of livelihood for both employer and employee, should be so conducted that due consideration is given to the situation of all persons dependent upon it. 2. The public interest requires adjustment of industrial relations by peaceful methods. 3. Regularity and continuity of employment should be sought to the fullest extent possible and constitute a responsibility resting alike upon employers, wage earners, and the public. 4. The right of workers to organize is as clearly recognized as that of any other element or part of the community. 5. Industrial harmony and prosperity will be most effectually promoted by adequate representation of the parties in interest. Existing forms of representation should be carefully studied and availed of in so far as they may be found to have merit and are adaptable to the peculiar conditions in the various industries. 6. Whenever agreements are made with respect to industrial relations they should be faithfully observed. 7. Such agreements should contain provision for prompt and final interpretation in the event of controversy regarding meaning or application.

Jan 6, 1919

My bets are on you, every time! But who is right? In the "cobalt issue" of our favorite magazine, January 1951, you stated: "By far the best immediate United States prospect for, large amounts of cobalt is the Blackbird mine of the Calera Mining Co., which is operating for Howe Sound Co., in Leinhi County, Idaho." In the March 1 issue of Saturday Evening Post, Ernest F. Mechlin, Jr., chief cobalt section, National Production Authority, states: "The Bethlehem Steel Co.'s Cornwall, Pa. ore bed is the principal domestic source." Maybe he should have said: "was the principal domestic source", or perhaps Howe Sound's Idaho cobalt is still in the prospect stage in Mr. Mechlin's opinion, perhaps in yours too. KATHARINE W. CARMAN GEOLOGIST 933 MICHIGAN AVE. EVANSTON, ILLINOIS Mr. Mechlin is correct in his statement that Cornwall is the principal domestic source of cobalt, but within the year, Blackbird production should greatly exceed that from Cornwall. Calera is expected to ultimately produce 3 million lb per year, whereas Cornwall averages 520,000 lb per year. -Editor.

Jan 1, 1952

INTRODUCTION It has been impossible for the student, the practicing engineer, and the geologist to find all of the essential elements of mineral appraisal and mineral economic analysis in a single text. Indeed, the most recent texts on mine evaluation are over 20 years old. Many of the basic principles of mine sampling and evaluation have not changed over the ensuing years, but with the advent of the digital computer the entire scope of mineral evaluation has been expanded to encompass superior techniques that heretofore were not possible when using manual methods. The old manual methods for ore reserve computations and the techniques for assignment of area of influence to drill-hole samples are now as antiquated as the Model-T Ford. With the computer making possible solutions that had not been practicable in terms of time and effort, it is important for the practicing explorationist and mining engineer to understand many of the new concepts and principles that can be applied with the resolving power of the computer. Many practicing mineral industry professionals have been disappointed by certain computer programs and thus have some reservations about computers being able to solve their very real problems. Often the gap between the practicing engineer and the ivory tower theoretician applying modern computer techniques is too broad to be bridged with scattered, fragmented publications. PURPOSE AND SCOPE OF TEXT It is the intent of this book to update and to unify a great many scattered reference works used in the mineral industry today. The ensuing pages are addressed both to the professional already working in the mineral industry who needs information on computerized methods as well as to the serious student seeking to grasp the fundamentals and modern techniques of mineral appraisal and feasibility. These techniques are based on sound mathematical principles and theory, with the computer as a tool-but a very essential tool-for the solution of the problems involved. The computer can be of value only if it is programmed by those having sufficient expertise to use its inherent problem-solving capability, and the output is interpreted by those who are sufficiently acquainted with its operation to understand the data it produces. In the pages that follow the author intends to outline in considerable detail all the essen-

Jan 1, 1980

By Roy Hardy

THE Getchell mine is a comparatively recent discovery in the old Potosi mining district, Humboldt County, Nevada, a district organized in the seventies and eighties, in which some prospecting was done in several metamorphic zones along a monzonite-sedimentary contact. The district had no production in the early days and no further work was done until the same metamorphic zones were prospected for tungsten (scheelite) in 1917 and 1918, when a few small lots were shipped. It again lay dormant until 1934, when prospectors investigated a large siliceous escarpment at one end of the old district where outcroppings were a prominent feature of the topography. Undoubtedly, during the early prospecting of the district, the outcroppings had been investigated for mineral, probably by panning, with negligible results because the gold later found is invisible in the concentrate and is refractory. A fire assay revealed the presence of sufficient gold to warrant develop-ment work. The outcroppings were easily prospected by short tunnels having their portals in the siliceous material on the hanging-wall side, with a maximum distance to crosscut to the footwall of 135 ft., or a distance at right angle to dip of 60 to 90 ft. Development work, reaching a depth of over 600 ft. on the dip of the vein, was done by means of various crosscut tunnels, winzes and laterals. A churn-drill hole was also sunk, which intersected the vein at a depth of 1100 ft. on the dip. Sufficient development work of this character was completed by 1937 to justify the erection of a reduc-tion plant to roast the sulphide ore and cyanide the calcine, and to treat the oxidized ore by straight cyanidation, to make a doré bullion for shipment to the mint. The erection of the plant was started that year and finished early in 1938, with a combined capacity of about 800 tons per day. It has operated continuously since erection and recently was enlarged to handle 1000 tons per day. The vein dips with the slope of the mountain, and by stripping the hanging wall the ore may be mined by power shovel for several hun-dred feet below the outcrop. Thereafter underground methods will be necessary.

Jan 1, 1940

By David R. Mitchell, R. B. Hewes

MANY processes for cleaning coal that are in use depend primarily on physical properties of coal and refuse other than specific gravity and surface conditions relating to froth flotation. These properties are shape, coefficient of sliding friction, resilience, friability, magnetic susceptibility, and electrical conductivity. In many of these processes specific gravity does have some effect and many separators are designed to utilize more than one of the physical properties cited. Although the processes described herein do not have a widespread application, yet for specific coals and specific conditions, they are economically important. A problem confronting many coal-mining districts is the marketing of the slacks or screenings and dust passing the final sizing screens. Processes in commercial use installed primarily to increase the form value, and hence the market value, of these slacks and dusts include briquetting, packaging, and low-temperature carborization. MECHANICAL PICKERS Machines utilizing shape, fictional resistance, and differences in resilience of coal and impurities are usually called mechanical pickers. They require a closely sized feed, therefore their use is confined to the pea, nut, and egg sizes. Various types of these devices are described by Berrisford, 1, 2 Taggart, 3 and Peele. 4 Shape In general, coal differs in shape from its accompanying dirt throughout the range of commercial sizes. Coal, breaking into roughly, cubical particles, contains a greater number of axes that are approximately the same length than does the dirt. The latter, consisting of pieces of slate and shale and lenses of pyrite, is flatter in nature. Further, flat coal often has a dirty, slaty appearance, even though of high quality. Mechanical pickers known as flat pickers, or "flatters," are widely used in the Pennsylvania anthracite region to remove flat coal from the final clean coal. This practice greatly improves the appearance of the final market product.

Jan 1, 1943

MINING; SOLUTION U.S. 4,066,297 - In the solution mining of uranium from an underground deposit of uranium ore using an alkaline leaching solution, precipitation of alkali metal salts is avoided by maintaining the Injected leach solution of an alkaline carbonate or bicarbonate and an oxidant undersaturated with respect to carbonates Undersaturation is effected by use of a water softening unit or by bleeding a portion of the recycled alkallne leach solution. A P. Spence, assigned to Atlantic Richfield Co Jan. 3, 1978 4 pp. (299-4). Filed: 6-1-76 (69 1,344)

Jan 1, 1979

By J. S. Levine, M. Prats

Several methods are available for calculating the performance of solution-gas-drive reservoirs from the PVT properties of the oil and from the relative permeability and other properties of the formation. These methods require a number of simplifying assumptions. The present method of computation has made use of a high-speed computer to solve simultaneously the nonlinear partial differential equations that describe two-phase flow by solution-gas drive in order to calculate the performance of a reservoir. Some of the results obtained by the nonlinear partial differential equation solution are compared with those obtained with an approximate method, which has been called the semisteady-state solution. The pressure and saturation profiles from the wellbore to outer boundary calculated by the two methods are compared for one constant-terminal-rate case and two constant-teminal-pressure cases. The agreement in these profiles, as well as in the values of average reservoir pressure and cumulative recovery, leads to the conclusion that, for most engineering calculations, the semisteady-state method will give a reasonable approximation to the numerical solution of the differential equations describing solution-gas drive. An unfavorable (as regards ultimate oil production) set of relative permeability curves was used in the calculations in the belief that the effect of the parameters which were studied would be emphasized to a greater degree. Furthermore, the reservoir was assumed to be completely homogeneous, and these results should not be considered applicable to any other type of reservoir. Gravity effects are not considered. The absolute permeability was varied from 25 to 0.5 md. At an economic limit of 2 B/D, the recovery for a 25-md reservoir is about 1.8 times as great as that for a 0.5-md reservoir. The effect of permeability on the producing gas-oil ratio is minor. Once PVT properties of the oil and the relative penneability properties of the reservoir are fixed, the pro- during gas-oil ratio is found to be a function of the fraction of oil recovered. Well spacings of 10, 40 and 80 acres were considered. For the assumed homogeneous-reservoir properties, the effect of spacing on recovery at an economic limit of 2 B/D was very slight. Certain dimensionless groups can be used to extend the results to other fields having different penneabilities, spacings, reservoir thicknesses, well radii and porosities, so long as the PVT and relative permeability properties are similar to those used in this paper. INTRODUCTION An important aspect of reservoir engineering is the prediction of the performance of the reservoir based on the limited information normally available early in the life of a field. Usually, soon after a field has been discovered, it is necessary to decide upon the spacing to be employed and the production program to be used for most efficient utilization of reservoir energy. Where these decisions have not been dictated by legal or political considerations, they have frequently been based on experience factors which indicate that two fields with similar characteristics will probably have similar performances. To the extent that the industry has been successful in economically exploiting oil reservoirs, this rule-of-thumb method has been found to have merit. A large amount of theory has been developed with which it is possible to predict the performance of a reservoir by using certain known properties of the oil and the formation. Because of the difficulties of the mathematics involved for a drainage area having square or rectangular boundaries, the problem usually has been simplified and idealized by assuming each drainage area to have radial symmetry and the field to be represented by a number of these drainage areas. Muskatl was one of the first to formulate the theory for two-phase flow and to solve the equations for a few cases by numerical integration, using the relatively slow means of computing available at that time. His equations describing

ALTHOUGH the refining period of the heat is generally defined as A starting after the charge has been completely melted, it may more properly be considered as beginning with the first efforts to facilitate the shaping up of the slag and the making of corrective additions for the control of slag or metal composition. Such actions may be initiated during the latter half of the lime boil. The early part of the refining period may, then, in essence overlap the latter part of the melting period. The primary aims of the refining period are to reduce phosphorus and sulphur from the steel bath to levels safely below the maximum contents specified, to eliminate carbon as rapidly as possible and still allow time for proper conditioning of the slag and attainment of the necessary bath temperature, and to deliver the heat ready for tapping or furnace deoxidation, with slag in the proper physical and chemical condition, and with carbon and oxygen contents and the temperature of the steer bath at the proper levels for the composition and grade of steel being produced. The particular conditions that fulfil these aims are distinctly different, depending upon whether the steel is to be finished according to fully-killed, semikilled, or rimming practice and also depending upon the carbon range specified. Regard- less of the type of charging practice employed, the object of the refining period is to produce repeatedly the desired finishing and tapping conditions for the grade of steel being produced. The variations and proportions of raw materials used in the charge may cause some variations in the degree of control required during refining, but not in the method of control. The refining period can therefore be discussed from a viewpoint largely independent of charging and melting practice. SHAPING UP THE SLAG In the first helper's vocabulary, refining practice consists in "shaping up" his heat. This includes elimination of sulphur, phosphorus, and carbon, putting the slag in proper condition, and adjusting bath temperature. Shaping up the slag is a major consideration because

Jan 1, 1944

By Enrique Touceda, Henry M. Howe

This paper gives the composition of the iron and slag at different stages in the " air-furnace" process of preparing " hard metal," or white castriron, for conversion into malleable cast-iron by annealing. The details of the process are given in an appendix. One of us had been trying for years to work some chemist of some of our malleable-iron plants up to a degree of enthusiasm which would lead him to make such an investigation. It would have had the advantage of the greater familiarity with the conditions which one habitually on the spot must have. Failing in this, he made use of an opportunity which presented itself of taking samples here represented, with such fairness as the conditions permitted, holding firmly that a rough approximation to the truth is better than the complete lack of data, or that a bird in the hand is worth two in the bush. We hope that this attempt may stimulate others effectively to duplicate this work, and thus correct or confirm it. Our results are shown in Table I. and graphically in Figs. 1 arid 2. Discussion.—At the time when the first two samples were taken, the metal and slag were still too sluggish to permit fair sampling, and not until sample 6 were the conditions really favorable, because at the time of the fourth sample the metal was not fully melted, and even at the time of sample 5 it was still sluggish. Indeed, the slag was probably very heterogeneous throughout, because it took up silica and alumina rapidly from the bottom, and because it was so siliceous as to be sluggish at this relatively low temperature. This hetero-geneousness is exaggerated in the two samples of slag 8, apparently by the great viscosity due to its extraordinary acidity. Note that the manganous oxide of one sample is about two and

Jan 1, 1909