Search Documents

Jan 1, 1881

By G. R. Wilms

A study has been made of the structural changes in polycrystalline high purity aluminum during the tertiary stage of creep under conditions of constant tensile load. It appears that there is no basic modification in the particular mechanism of deformation that characterized the preceding secondary stage of creep, but that the changes in crystalline structure produced during the tertiary stage are only a consequence and not a cause of the accelerated strain. Intercrystalline fissures were observed on entry into the tertiary stage, and these might supplement the accelerated rate of strain owing to local stress concentrations. There is evidence that the formation of these fissures may be associated with the presence of surface imperfections, and it is suggested that a more generalized treatment of the results may explain certain creep characteristics of commercial alloys. IN previous work'-4 a study was made of the changes produced when specimens of annealed aluminum were deformed at various temperatures and rates of strain, especially under conditions leading to creep under constant tensile load. It was shown that, as the temperature was increased or as the rate of strain was decreased, elements of the substructure produced within the grains became coarser, and with the strain rate constant at a given temperature, their size tended to an equilibrium value. The preliminary process of the breaking down of the grains into a substructure was identified with primary creep.' The subsequent equilibrium, condition was associated with secondary creep. The question then arose whether the tertiary stage corresponded to any further significant change in the substructure. The question is also of interest in view of the opinion, expressed for instance by Andrade,5 that the tertiary stage is merely an accelerated rate of strain due to the reduced area of section of a specimen under continuous tensile load, and the other opinion, as suggested by the observation by Sully, Cale, and Willoughby6 of a tertiary stage in com-pressive loading, that this third stage is a real effect in its own right. The object of this paper is to record some observations on the tertiary stage of high purity aluminum. Experimental Procedure The material was aluminum of 99.98 pct purity as previously used. The specimens had a rectangular section of l/8 x l/2 in., and extensions were measured over a 1 in. gage length. After machining to shape, the specimens were annealed to give a standard grain size of 0.2 mm and then electropolished. The general procedure involved metallographic and X-ray diffraction examination at progressive stages of elongation (marked by arrows on the curves shown in Figs. 1 and 2), the specimen being extended to fracture under constant load at a given temperature. The X-ray tests were made by the back-reflection method from a stationary specimen, using CoK radiation. The longer edge of the micrographs in the paper corresponds to the direction of applied stress. Results The previous work showed that, in the secondary stage of creep in aluminum, three basic types of structure could be developed according to the temperature and rate of strain. These were: 1—slip, which predominated at the lower temperatures and higher rates of strain and produced the finest and least perfect substructure; 2—cell structure, which superseded slip as the temperature was raised and the rate of strain decreased and which was characterized by a coarser and more perfect structure and an absence of slip lines; and 3—a stage termed "boundary microflow," which predominated at still higher temperatures and lower rates of strain when the cell size had increased and become comparable

Jan 1, 1955

By R. D. Parker

LARGEST of any hoist installation ever manufactured in Canada is that being erected at No. 5 shaft, Creighton mine, of the Inter- national Nickel Company of Canada, Limited. It is a bicylindrical conical- drum hoist with the drums arranged in tandem, and driven by two direct- current motors through single reduction gearing. This hoist was designed by the Canadian Allis-Chalmers, Limited and manufactured at their works in Lachine, Quebec.

Jan 1, 1936

By Galen H. Clevenger

THE real and permanent advances which take place in any industry are for the most part slow evolutions which frequently develop and grow almost imperceptibly from clay to clay. A meritorious idea may and generally does require long and patient development and commercial application under a variety of conditions and in a number of localities before it emerges as standard and generally accepted practice. There must be not only technical perfection but also economic advantage. Thus a cross-section taken at any particular time of an industry may reveal little that is distinctly new and yet there may have been considerable progress. During the past year there has been little that is new in milling and yet there has been real progress; some problems have been solved and some of what we may term the newer developments have become more firmly, established.

Jan 1, 1930

By AIME AIME

STEADY advance has been made in the art of lead smelting and refining during the year. The bringing of natural gas to the Salt Lake valley has led to its adaptation to lead smelting operations. The Tooele plant of the Anaconda Copper Mining Co. has put into practice the high blast pressure and constant volume for lead blast furnaces, which we understand was first advanced by John F. Austin. It would appear that within limits, capacity is nearly proportional to the volume of air. If the charge is dense, a constant pressure, as in the old practice. did not get much air through the charge and the furnace slowed up. The constant volume idea makes the charge smelt at the same rate as if the charge were porous. The cost of a little additional power insures capacity operation at all times.

Jan 1, 1932

By Charles Behre

THIS paper deals with recent geologic studies in the slate belt of Northampton, Lehigh and Berks counties, Pennsylvania. The work was conducted under the auspices of the Pennsylvania Topographic and Geologic Survey. Three years have now been spent in detailed consideration of the economic geology of this region. In the field, particular attention was paid to the bearing of geology on quarry development and property valuation and the object of this paper is to summarize the results from that viewpoint. Excellent studies of a somewhat similar nature have already been carried out by Bowles,1 but with the emphasis upon the details of quarrying and fabricating methods, rather than upon the geologic relations. THE NORTHAMPTON-LEHIGH-BERKS DISTRICT Location The region here discussed lies in east-central Pennsylvania and extends southwestward from Delaware River, on the New Jersey line, to the Schuylkill in north-central Berks County. It is an elongated belt occupying the northern sections of the three counties mentioned and lying along the southern edge of Blue Mountain. Its length is about 50 miles and its average width five or six, though in places it attains a maximum of 10 miles.

Jan 1, 1928

By AIME AIME

As already announced in the January Bulletin, this publication will be issued during the coming year monthly instead of bi-monthly as heretofore. Among other reasons for this change, it is desired to effect thereby the earlier transmission to members of important papers, lists of candidates for membership, and other items of timely information. Spokane Meeting and Excursions. Further details of the' 97th meeting of the Institute have been sent to members in the Circular of May 8, 1909. For, convenience of the members a summary of the additional in¬formation is here presented. A special train of Pullman cars will leave Chicago about September 15. This train will be side-tracked at all places visited, and the sleepers will be available for lodging and the dining-car for meals during the entire trip, except during the Yellowstone Park tour. The general. cost of the trip per member will be $300, which includes transportation, berth, and meals for the entire trip from Chicago back to Chicago, almost 6,000 miles, and the tour through Yellowstone Park, occupying in all about 30 days. Special accommodations on the train will be furnished at the following, rates

May 1, 1909

By David L. Riley

Organization The Foundling Years - 1901-1921 Two events that occurred in the decade of the 1870's have had far- reaching effects upon the petroleum industry in the U. S. and formed a basis for the birth and growth of the petroleum engineering profession. In 187 1 a group of mining engineers banded together to form the American Institute of Mining Engineers "to promote the arts and sciences connected with the economic production of the useful minerals and metals and the welfare of those employed in these industries by all lawful means". Although it was to be 30 years before an event in Jefferson County, Tex., would cause petroleum to come into prominence as the world's principal source of energy, the founding of AIME provided an organization through which the application of engineering to the recovery of petroleum and natural gas could be developed. In 1875, a Pennsylvania judge who was called upon to make a decision for which there was no precedent reasoned that oil and gas were like wild game - they belong to the man who can reduce them to possession. His decision sired the "rule of capture", which stated that a landowner possesses the oil produced from his well, even though it might have come from beneath his neighbor's land. This interpretation prevailed for more than half a century, during which time gold-rush tactics were employed in the drilling and production of many oil fields in the U. S. The resulting overproduction and tremendous waste led to a virtual economic collapse of the U. S. petroleum industry by the early 1930's. To bring these malpractices under orderly control, proration and conservation policies were developed, and petroleum engineering became the medium through which they were devised and implemented. At the turn of the 20th Century, more than 90 percent of this country's oil production came from the East, but the picture changed with dramatic suddenness on Jan. 10, 1901. Captain Anthony F. Lucas, an Austrian mining engineer, had noticed concentrations of oil and gas near salt domes during mining operations on the Louisiana Gulf Coast. In 1899 he leased a low mound near Beaumont, Tex., began drilling, and after almost 2 years of intermittent operations, brought in the famous "Lucas Gusher"

Jan 1, 1971

By T. S. Lundy, R. E. Pawel

Effects of short-circuiting paths on observed diffusion behavior in real crystalline systems are considered. It is concluded that experimentally measured diffusion coefficients may vary widely from values associated with true lattice diffusion to those appropriate for short-circuiting paths alone depending upon the conditions of the experiment and the sensitivity and completeness of the data. IN 1961 Harrison1 classified experimentally observed diffusion behavior in systems involving both lattice and dislocation-enhanced atomic transport into three categories. His types A and C were limiting cases where the measured diffusion coefficients using the usual serial sectioning techniques were representative of lattice diffusion (with only slight effects of dislocations) and dislocation-network diffusion (with only slight effects from lattice diffusion), respectively. In both cases A and C for a sectioning experiment in which the diffusion couple has the semi-infinite geometry and unidirectional diffusion takes place from a plane source located at the origin of the coordinate system, he pointed out that Gaussian penetration behavior should be observed. For case A the lattice coefficient should be slightly enhanced by dislocation contributions, and the model of Hart2 can be used to predict the amount of this enhancement. For case C the observed coefficient should be that for the dislocation network and have little or nothing to do with lattice diffusion. Hart's model in its general form is still applicable, but the apparent diffusion coefficient for this case is virtually independent of dislocation density. Harrison's case B is that for which non-negligible contributions exist for transport by both mechanisms and "the concentration distribution does not approximate to any simple form." With the possible exception of very low temperatures where diffusion distances approach atomic dimensions, any real diffusion specimen will in general show non-Gaussian behavior provided the data are complete enough to uncover it. Thus, a "complete" set of data for any real system cannot be expected to be totally amenable to treatment by a simple mathematical model which does not take into account the relative distribution of transport by the various modes or submodes. For a particular sensitivity of specimen analysis and at a given temperature of annealing if the concentration profile could be observed as a function of time, "the behavior will initially be type C, and will develop into type B. and ultimately type A".1 Thus, it appears that the type of diffusion behavior which is experimentally observed in a given system depends very much upon the particular experimental conditions and the particular tools available to obtain the data. Interpreted in this fashion, Harrison's classification refers not to the diffusion behavior as a whole but to the relative sensitivity of the method of examination and completeness of the data. In the present paper we will: 1) assume that the measured penetration behavior follows the same general classification as that proposed by Harrison; 2) give, for diffusion in tungsten, examples of the range of diffusion coefficients that it is possible to obtain in a single experiment; and 3) speculate that some arguments which consider the possibility of short-circuiting effects being responsible for "anomalous" diffusion in several bcc metals may have been discarded prematurely.3 Both monocrystalline and polycrystalline tungsten were used in this work. The former was obtained as triple-pass, electron-beam zone-refined 6.0-mm-diam rod from Materials Research Corp.. Orange-burg. N.Y. The latter was swaged, high-purity bar stock which was annealed for 2 hr at 2200°C and 10-9 torr to yield an average grain diameter of about 25 /i. The tracer Nb95 was received in oxalate solution from the Isotopes Division, Oak Ridge National Laboratory. Experimental procedures of specimen preparation, isothermal diffusion annealing, serial sectioning by anodizing-and-stripping, and y counting of the individual sections to determine the tracer penetration profile after a given diffusion anneal have been described elsewhere.4 However, it should be noted that the anodizing-stripping sectioning technique has the particular advantage for this research of permitting sectioning to be accomplished over a wide range of

Jan 1, 1970

By J. D. Vincent, Pierre R. Hines

INTRODUCTION OF FROTH FLOTATION INTO THE UNITED STATES "The introduction and development of the flotation process have proved to be of such momentous importance to the mining industry of the United States that they deserve to be considered historically ." T. A. Rickard l James M. Hyde installed the first froth flotation process in the U. S., about Aug. 1, 1911, at the Basin Reduction Co. plant, Basin, Mont., which was then under lease to the Butte and Superior Copper Co.2 Two months later, the Minerals Separation Ltd.. filed suit in the U. S. District Court of Montana against Mr. Hyde char& him with infringement of their Patent 835, 120/1906. The U. S. District Court decided in favor of Minerals Separation Ltd. on July 28, 1913. This decision was reversed by the Ninth Court of Appeals in San Francisco on May 4, 1914. Then the U. S. Supreme Court, on Dec. 11, 1916, upheld the patent on three counts only but restricted it to 'the use of less than one percent of oil.” The Miami Copper Co. was sued by Minerals Separation on Oct. 10, 1914, for infringement of Patents 835,120 and 962,678, and 1,099,699. The Miami Copper Co. was operating under John M. Callow's froth flotation process Patent 1,104,755/~uly 23, 1914. Miami lost this suit in the District Court of Wilmington, Del., and appealed to the Court of Appeals, Third Circuit, Philadelphia. The Third Court of Appeals decided against Miami, May 24, 1917. The case was referred to a Master and hearings to determine profit and damages were not settled until 1923. Nevada Consolidated Copper Co. was sued Sept. 9, 1919, and Magma Copper Co. was sued Jan. 10, 1920. Thus, the first ten years of froth flotation in the U. S. were beset by patent litigation. This litigation suppressed the free circulation of new discoveries or useful information that might be cited in a patent suit against the originator; it accounts for many of the blank spaces in the historical record. T. A. Rickard3 has reviewed the history of flotation and has given the chain of discoveries, patents, and processes that resulted in froth flotation. He has re- ported also on the patent litigation beginning in 1911 and ending in November 1923, when Minerals Separation's Patent 835,120 expired. He comments on

Jan 1, 1962

By Robert W. Thomas

LEACHING of mined-out areas at the Arizona property of the Ray Mines Division, Kennecott Copper Corp., was started on Jan. 20, 1.937, and by July 1, 1938, 10,000,000 lb. of copper had been produced by this method. Leaching operations at present are confined to the western portion of the ore body and over an area of approximately ten acres. The ore in this area was extremely high in pyrite and the copper content, which averaged slightly in excess of 1 per cent, was the result of incomplete secondary enrichment by solutions which apparently worked laterally from the main ore body. Above the ore was an unaltered zone of primary or protore averaging 125 ft. in thickness and containing approximately 0.6 per cent copper. Above this was the capping or leached zone averaging 50 ft. thick.

Jan 1, 1938

By J. R. Campbell

In order to discuss the subject intelligently, it will be necessary to touch briefly on the forms in which sulphur is supposed to exist in coking coal to be carbonized in beehive or byproduct ovens. Sulphur is known to exist in coal as sulphides and sulphates, as can be determined experimentally. Then there is the so-called organic sulphur, i.e., sulphur in combination with the carbon, 'hydrogen, and oxygen of the coal, about which much has been written, but nothing definitely proven in an experimental way. In fact, so far. as we know, there never has been developed a satisfactory and conclusive method in the laboratory for the direct determination of organic sulphur. For most coking coals, it can be safely assumed that the preponderance of sulphur is in the form of pyrite (FeSz). When exposed to comparatively low temperatures during the coking process, it loses its sulphur according to the following chemical reaction: 7FeS2 = Fe7Ss + 6S. It will be seen, therefore, that six out of the 14 atoms of sulphur (or 42.8 per cent.) are expelled, or volatilized. FelSa remains in the coke as pyrrhotite, or magnetic sulphide of iron; this accounts for the highly magnetic properties of the powdered coke. A more commonly accepted reaction is FeS2 = FeS f S, in which the straight sulphide of iron is produced with 50 per cent. volatilization of sulphur. In the beehive methods of coke making, air is introduced in sufficient amounts to carry on the distilling and the coking processes, and the sulphur is oxidized along with the other volatile products: First, into sulphur dioxide (SO2), known by the pungent andsuffocating odoremitted from the trunnel head; second, into sulphuric anhydride (SOa); and, finally, into sulphuric acid, as it comes into contact with the air and moisture. In a properly regulated draft on a beehive oven, there is never complete combustion of the gases. In other words, the coking process should be carried on in a reducing atmosphere, and a low-grade producer gas kept issuing from the trunnel head. For coals of about 30 per cent. volatile matter, the ratio of air to gas is 3½ to 1. In complete combustion, the ratio is 6 to 1, producing an extremely high temperature

Jan 1, 1916

By W. F. NETZZEBAND

THE long-hole drill has been used for prospecting underground in the tri-State district for several years, and its value has been pretty thoroughly proved. An attempt was made to get a statement of their experience with the machine from all the operators who were known to have used the machine. The majority of them replied to the questionnaire so that this paper is practically a summary of the experience of the district, together with some practical details taken from the experience of the Eagle-Picher Lead Company. When the drill was first used by the Eagle-Picher Lead Co., it was put in low headings and was mounted on a cross-arm supported by two drill columns. This was found to be a rather awkward method of mounting, because fairly long moves were made and the same drill columns could not be used on any two successive set-ups. The machine was later moved to a mine with high headings so that this type of mounting was found to be impractical. A heavy tripod was tried and found satisfactory, provided care was taken to see that the set-up was solid. The Evans-Wallower Lead Co. and the Century Zinc Co. report using the double post set-up, but the headings are low in these mines. The Commerce Mining St Royalty Co. first used the double-post mounting in high headings by cutting a niche in the wall and setting the post in it. This proved to be a slow and expensive method and was later abandoned for the tripod. The Federal Mining & Smelting Co. has used a tripod throughout its operations. Great care must be taken in using the tripod to see that the set-up is solid. Wherever possible it is advisable to sludge in the legs and let them set a short time before the machine is put into use. Where high bottom is encountered the Eagle-Picher operator found it advisable to drill jack- hammer holes in the bottom and drive the legs into them.

Jan 1, 1930

By T. D. Jones

MUCH the same story can be told for the lead industry for the year 1945 as for the three previous years. In response to inquiries as to new developments, invariably the answer has been, "No new developments-our men either too busy with the man-power problem or trying to get production out." Time and efforts of industry have been concentrated for the most part on war or readjustment problems. Now that V-E and V-1 day have passed, the lead industry can justly be proud of its record in World War II. As in previous wars, lead played an important role and one of its most spectacular uses was in the production of the atomic bomb. We read that the part lead played was rather obscure, but as a protective agent, lead played a most significant role. "Since the materials in the Pile Plant are intensely radioactive, all storage and handling must be done behind thick concrete walls or lead shields. The material is never seen and all operations are auto matically controlled by a foolproof remote control system especially designed for this purpose." (Chews. & Met., Sept. 1945.) When our armies invaded the European theater of war and made a landing on Normandy beach, gasoline and oil for the motive power were furnished through miles of armored lead pipe. This amaz-

Jan 1, 1946

By AIME AIME

WHETHER by the Mohawk Trail, Sound steamer, air plane, railroad or any other route or mode of locomotion, all roads will lead to Boston the week of National Metal Congress, Sept. 21-25. The Institute of Metals and Iron and Steel divisions of the Institute are then to meet jointly at the Hotel Statler, and the American Society for Steel Treating, the American Welding Society, the Society of Automotive Engineers and the Iron and Steel Division of the American Society of Mechanical Engineers present carefully planned programs at their respective sessions. The National Metal Exposition will be held on Commonwealth Pier.

Jan 1, 1931

By ELIHU THOMSON

IN 1877, Professor Thomson delivered at the Franklin Institute, [Philadelphia, five lectures on electricity. The object of the lectures and the demonstrations, which were numerous and many of them original even to the employment of special apparatus constructed by the lecturer, was to show clearly that electricity, of whatever name, was the same., differing only in tension (as it was termed) and in the current flowing, or quantity (the old term), in steadiness or in wave-like character. In those days, the textbooks divided the subject into statical and dynamic electricity, with sub-divisions such as frictional electricity, voltaic electricity, magneto electricity, electromagnetism, thermo electricity, and animal electricity. The well-known Ruhmkorff coil,' or spark coil as it is now called (as when used for the ignition of automobiles), was employed to step, up a battery current to a high-tension discharge which would charge condensers, such as Leyden jars.

Jan 1, 1921

By Thomas C. Patton, Eric S. Cheney

L-D gold mine is 3 miles south of Wenatchee, central Washington. Recognition of locally mappable conglomerates, sandstones, and shales within the Paleocene (?) Swauk formation led to the discovery that the known epithermal gold mineraliza¬tion is limited to a previously unknown imbricate thrust zone of unknown displace¬ment cutting the open folds o f the area. Hypabyssal intrusions also are most nu¬merous along the trace of the thrust faults. Yakima basalt of Miocene age uncon¬formably overlies the Swauk formation, thrust faults, and the intrusions. The L-D mine is in a northwesterly trending imbricate fault block of nearly vertical strata. Microscopic native gold, electrum, and naumannite occur in quartz veins and as low¬grade disseminations in the well-silicified portions of arkosic sandstones. Fault gouge on the "footwall fissure" limits ore to the hanging-wall block of the fault. Epithermal mineralization and alteration are spatially related to the nearby intrusions. Right lateral north-south faults offset the ore a maximum of 300-400 ft along any one fault. From 1949 until January 1967, when the L-D mine closed, 1,036,572 dry tons of ore valued at $14,962,305 and averaging 0.396 oz Au per ton and 0.607 oz Ag per ton were mined. Recognition of the structural control of the mineralization and altera¬tion within the Swauk formation suggests several areas within and outside of the mine that warrant further exploration. For example, the high-angle faults, imbricate thrusts, and the intrusions of this area are on strike with similar features along the major Entiat fault zone 10 miles to the northwest. The L-D gold mine (previously called Squilchuck, Wenatchee, Golden King, Gold King, and Lovitt) is located in Squilchuck Canyon about three miles south of Wenatchee, Chelan County, Wash. (Fig. 1) on the eastern edge of the Cascade Mountains. The major stratigraphic unit in the area is the nonmarine early Tertiary Swauk formation, which is predominantly com¬posed of arkosic sandstone. The lack of laterally per¬sistent units and the paucity of outcrops heretofore have precluded all but the grossest subdivision of the Swauk.' As a result, the true significance of the open folds in the Wenatchee area was not recognized, and although the geology within the mine was known, the structural setting of the mine was virtually unknown. During the present investigation, several locally map¬pable units were discovered within the Swauk which, in conjunction with mine maps, indicate an imbricate thrust zone. The epithermal gold mineralization, most of the hypabyssal intrusions, and the zones of hydrother¬mal alteration are located within or near this thrust zone. The purpose of this paper is to: (1) to describe this structural setting, rather than the detailed mine geology already presented by Lovitt and Skerl,2 and (2) to sug¬gest that from an exploration standpoint, this struc¬tural setting may be repeated in areas inside and outside of the mine area. Stratigraphy and Structure of the Swauk Formation General: The Swauk formation contains three distinct lithologies. Typical Swauk sandstone is gray on fresh surfaces, poorly sorted, weathers tan, and is cross¬bedded; it consists of 40-60% quartz, 20-40% feldspar, and up to 10% muscovite and biotite 9 The typical shale is gray to dark brown, very soft, and interbedded with silty sandstones; sharp contacts exist between the

Jan 1, 1972

By Walter W. Bradley, OLAF P. JENKINS

IN April of this year the California State Division of Mines (formerly known as the State Mining Bureau) observed its 50th anniversary. The Division serves as a bureau of information and, an encyclopaedia of California's economic minerals. Its primary function is to make economic surveys of the mineral resources of California, their development and utilization. Geological studies also constitute a related part of the work as being necessary in tracing and out- lining ore deposits and the most likely areas in which to find them. The results of the Bureau's data-gathering are published in the form of annual reports of the State Mineralogist, and in bulletins on specific substances. The Division is just completing a series of reports on the mineral resources of the State arranged by counties.. It is now starting .a new series of reports arranged according to substances particularly the so-called non- metallic commercial groups. Of these the following are now available: clays, barite, and mineral paint. These will be followed by reports on feldspar and silica, diatomaceous earth, limestone and others

Jan 1, 1930

By F. S. McNicholas, R. L. Healy

NOTEWORTHY because of the amount of explosives used, the tonnage broken, and the wide range involved both vertically and laterally, was a large underground blast fired last November at the Hidden Creek mine, Anyox, B. C. Stoping methods and mining prac¬tices at the Hidden Creek mine have previously been described in the technical press. Earlier mining methods employed included shrinkage stoping, glory-holing, and "spiral" stoping. The latter especially has been a practice peculiar to the Granby company, having been used for years at its Phoenix mines and later at the Anyox property where conditions as to size of orebodies and strength of ground both in the ore and walls were similar. These methods all leave tremendous excavations supported at key points by pillars and braces that may only be safely mined by big blasts.

Jan 1, 1935

By R. E. Boni, G. Derge

Application of surface tension measurements has been made to molten silicates in order to determine the effect of sulphur upon the surface tensions of synthetic blast furnace slags. In melts with the same molar ratios of AI2O3 + SiO2 to the basic oxides BaO, CaO, and MgO, the surface tensions increase in the order of oxides listed. Sulphur lowers the surface tensions of the basic BaO, basic CaO, acid BaO, acid CaO, and acid MgO slags in that order; and the concentration of excess sulphur at the slag surface increases in this same order of slags. The rate and amount of desulphurization of iron by these slags is favored by a low excess surface sulphur in the slag. IN a previous paper,1 the authors discussed the applications of surface tension measurements of molten silicates to problems of metallurgical interest. Of major importance is the aid that such studies lend to forming a working concept of slag structure. Since the ability of a slag to desulphurize metal depends strongly upon its composition,2"4 fundamental information about the structural differences between various slags which contain sulphur should aid the development of better desulphurizing media. For that reason, the present investigation concerns the effect of sulphur upon the surface tensions of synthetic blast furnace slags. Experimental Procedure , The maximum bubble-pressure method was used to measure the surface tensions of synthetic blast furnace slags in the temperature range 1300° to 1600°C. The method is based upon the equation which was developed by Schrödinger5 from a consideration of the forces of hydrostatic pressure and surface tension of a liquid which oppose bubble formation when a gas is forced through a tube immersed in the liquid. where y is the surface tension between argon and slag in dynes per centimeter; g is the gravitational constant, centimeters per second2; H is the manometer reading in centimeters; s2 is the density of manometer fluid in grams per cubic centimeter; S1 is the density of the medium in grams per cubic

Jan 1, 1957