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Ellsworth Daggett, who joined the Institute in 1873, and had beeu a prominent figure in the mining profession of Utah and other Western states for many years, died in San Francisco, Jan. 5, 1923. Mr. Daggett was a contemporary and intimate friend of Clarence King, James D. Hague, R. W. Raymond, and other Nestors of the mining engineering profession prominent in the last quarter of the nineteenth century. He was born at Canandaigua, N. Y., May 24, 1845; graduated from Sheffield Scientific School in 1864; pursued post-graduate courses there for two years, and for one year at the Bergakademie, in Berlin. He was in active practice as mining engineer from 1866 to 1914, but devoted most of his time during the World War to the perfecting of a submarine torpedo. He was connected with the United States Geological Exploration of the Fortieth Parallel in 1870. The plates illustrating mining industry, Volume III of the reports of that survey, were engraved from drawings obtained in the field during progress of the survey and prepared for the engraver by Mr. Daggett. He operated the Winnamuck mine and smelter at Bingham Cation, Utah, in the early seventies; the mines and mill at Cusihuiriachic, Chihuahua, 18867; and the Berlin mine near Austin, Nevada, 1904-6. On June 24, 1874, Mr. Daggett married Miss June Spencer, of Salt Lake City, who survives him, residing in New Haven, Corn. Appointed United States Surveyor General for Utah by President Harrison, in 1888, he was the first engineer to hold that office in Utah. He reorganized the mineral division of the office, required the courses of mineral surveys to be referred to the true meridian determined by solar or stellar observations, and did much to improve the accuracy and reliability of such surveys. Mr. Daggett was a member of the Alta and University Clubs of Salt Lake City, and president of the latter from 1890 to 1892; he was also a member of the Century Club, New York. Through his instrumentality, irrigation was brought to considerable tracts of land in northeastern Utah, and Daggett County of that state is named for him. Re wrote numerous technical papers, and an economic review entitled "A Quarter of a Century of Prices," in which was shown the close relation

Jan 1, 1923

Ellsworth Daggett, who joined the Institute in 1873, and had beeu a prominent figure in the mining profession of Utah and other Western states for many years, died in San Francisco, Jan. 5, 1923. Mr. Daggett was a contemporary and intimate friend of Clarence King, James D. Hague, R. W. Raymond, and other Nestors of the mining engineering profession prominent in the last quarter of the nineteenth century. He was born at Canandaigua, N. Y., May 24, 1845; graduated from Sheffield Scientific School in 1864; pursued post-graduate courses there for two years, and for one year at the Bergakademie, in Berlin. He was in active practice as mining engineer from 1866 to 1914, but devoted most of his time during the World War to the perfecting of a submarine torpedo. He was connected with the United States Geological Exploration of the Fortieth Parallel in 1870. The plates illustrating mining industry, Volume III of the reports of that survey, were engraved from drawings obtained in the field during progress of the survey and prepared for the engraver by Mr. Daggett. He operated the Winnamuck mine and smelter at Bingham Cation, Utah, in the early seventies; the mines and mill at Cusihuiriachic, Chihuahua, 18867; and the Berlin mine near Austin, Nevada, 1904-6. On June 24, 1874, Mr. Daggett married Miss June Spencer, of Salt Lake City, who survives him, residing in New Haven, Corn. Appointed United States Surveyor General for Utah by President Harrison, in 1888, he was the first engineer to hold that office in Utah. He reorganized the mineral division of the office, required the courses of mineral surveys to be referred to the true meridian determined by solar or stellar observations, and did much to improve the accuracy and reliability of such surveys. Mr. Daggett was a member of the Alta and University Clubs of Salt Lake City, and president of the latter from 1890 to 1892; he was also a member of the Century Club, New York. Through his instrumentality, irrigation was brought to considerable tracts of land in northeastern Utah, and Daggett County of that state is named for him. Re wrote numerous technical papers, and an economic review entitled "A Quarter of a Century of Prices," in which was shown the close relation

Jan 1, 1923

By E. E. Barker

ALTHOUGH flotation was known to be a successful process prior to 1912, Utah Copper Co.'s ores were not entirely treated by this process until 1923. Experiments had been conducted, of course, prior to that time, and in February, 1917, the first unit of the Arthur plant was changed over from gravity concentration to flotation. On May 16, 1918, the entire Arthur plant was on flotation, excepting the coarse concentrate which was tabled prior to fine grinding. The reasons for the delay in adopting flotation at these plants were, first, that it was decided to await the outcome of the litigation with the Butte & Superior Mining Co., which began with an injunction served on Oct. 3, 1911. This litigation continued for years. Then the demands on the plants in the war years 1916, 1917 and 1918, really precluded any further drastic changes during that period, as all efforts were bent on maximum tonnage, and the cry of tonnage, rather than of recovery, was the major issue. The postwar depression followed these years of intensive production, so that it was not until 1922 that the Magna plant was equipped to use this process. Excepting, then, the amount of coarse concentrate that was tabled, 1923 was the first year when the Utah Copper Co.'s ores were on, a full flotation basis. EFFECT OF FLOTATION ON ORE RESERVES The object of this paper is to point out the effect that flotation has had on the operations of the Utah Copper Co. In 1905, when D. C. Sackling began making history in copper, the ore reserves were 34,000,000 tons, with a grade of 2 per cent. copper and a mill capacity of 700 tons daily. The point of cut-off between nonprofitable and profitable grades was 1.2 per cent. A few years later the capacity was increased to 6000 tons, when 1.1 per cent became the point of cut-off. Ore reserves had climbed to 80,000,000 tons, having a grade of 1.9 per cent. In 1911 there was an ore reserve of 300,000,000 tons, with a grade of 1.5 per cent and a cut-off of 1 per cent.; in 1918 the ore reserve was approximately 400,000,000 tons, and a grade of 1.38 per cent., and point of cut-off 0.95 per cent., based on normal costs and prices. Up to this

Jan 1, 1928

By Graham John Mitchell

In May, 1919, a crosscut on the 1400-ft. level of the Briggs mine, a Calumet, & Arizona property at Bisbee, Ariz., penetrated a deposit of pyrite and chaleopyrite that had replaced quartzite and limestone and was cut, especially in the quartzite, by numerous fractures. As the drift advanced through these fractured portions, they were found to be free from copper-sulfate minerals although '(sooty" chalcocite was present in the fractures and also as coatings and replacements of pyritc. Howcver, sulfate soon made its appearance in certain fractures, filled them, and began to form stalactites. Several centers of incipient growth were noted for subsequent study, observations in the drift at frequent intervals during the past 17 months affording the opportunity of determining the rate of formation of the stalactites. The one to attain the greatest growth during the period of observation measured 27 in. long and averaged 1 in. in diameter. A close study showed it to be composed of small interlocked crystals of chalcanthite radiating from a small central tube-like opening. The trielinic form of the crystals was evident with prism and pinacoid faces recognixable. Assuming that the supply of copper-sulfate solution was constant (luring the 17 months—-and such an assumption is supported by the fact that the number of drops of excess solution falling, per minute, from the tip of the stalactite at the times of observation checked closely—thc stalactite, it has been estimated, grew at the rate of 1.58+ in. per month. DISCUSSION James I?. Kemp," New Yolk City.—J. S. Curtiss, in the monogr:tpll on Eureka, Ncv., say:: that a stalactite formed in limestonc grew 5/8 in. in three weeks and continued to grow as long as it had a drop of water or solution at the lower end. Another grew at the rate of 3/8 in. in the same time. In the case cited by Mr. Mitchell, the growth was about 136 in. in three weeks. A year ago we had an instance of the formation of cubes of galena on a railroad spike. A mine in northeastern Oklahoma had been idle about two years but on account of pumping of neighboring properties, the circulation of water was active throughout the drift. A cube of galena,

Jan 1, 1922

By Philip W. Moen

It is with sincere regret that the members of the Institute will have heard of the death, on March 17th last, at Terre Haute, Ind., of Professor Charles 0. Thompson, A.M., Ph.D., President of the Rose Polytechnic Institute of that city, and for many years pre viously the head of the Worcester County (Mass.) Free Institute of Industrial Science, and in 1881 and 1882 one of the managers of this society. To us he was chiefly known by the excellent character of the work which he had performed, as a recognized leader among the technical educators of the country. He was a constant, and interested atten dant at our meetings, seeking to acquaint himself not less with all that was noteworthy in the practical attainments and developments of the branches of industry represented by our membership, than with such such facts as would be of service to him in shaping or guiding a wise course of instruction in the institutions of which he had charge. We shall not soon forget him, or the genial courtesy of his manner, or his ready words and thoughtful comments. Charles Oliver Thompson was born September 25th, 1836, at East Windsor Hill, Conn., where his father, Rev. William Thomp son, D.D., was professor in the Connecticut Theological Seminary, since removed to Hartford. The son was fitted for college under the late Paul A. Chadbourne, and entered Dartmouth College in 1854. He was graduated in 1858 with honors. In all the studies of his course he had maintained a high rank, but showed marked proficiency in chemistry and mechanical philosophy. In 1861 he received the degree of A.M., followed by that of Ph.D. from his own college in 1879, and from Williams in 1880. In September, 1858, the year of his graduation, he became principal of the Peacham Academy, Vt., remaining in that position until November of 1864, though during that period he devoted several months to practical work as a surveyor and civil engineer. Thus his experiences were developing the qualities which, later on, fitted him to carry out so successfully the plans of the thoughtful projectors of a new system of technical education, along a path before untrodden, but which the test of time and the indisputable proof of success have shown to be both wise and fruitful.

Jan 1, 1886

THE Rocky MountainClub brought into the East the spirit of the West; the impulse to build, to develop, to accept unquestion-ingly the comradeship and help of any straight shooter who had it in him to accom-plish things and a will to work. That this was the spirit of the Club was due to its leaders. It was their spirit and they attracted around them men of the same stamp. Among those who made the Club what it was no one had larger in-low fluence than William Boyce Thompson, the vice-president and chief of financial staff. It was characteristic of him that the same financial genius that was employed in building up Nevada Consolidated, In-spiration, Magma, Texas Gulf, and as director of the Metro-politan Life and the Federal Reserve Bank, was freely placed at the service of the Club. It was equally char- acteristic that the generosity that financed the Red Cross Mission to Russia inspired the use of the Club funds for Belgian and war relief. "W. B.," as he is known to his many friends, was born at Virginia City in Alder Gulch, Mont., on May 13, 1869. His father, William Thompson, born at Cobourg, Ont., had drifted into the old Northwest and, hearing at Yankton of the gold strike at Bannack, crossed the plains on the Oregon trail in the summer of 1863, arriv-ing in Alder Gulch at the inception of a mining boom that lasted several years, during which something like $60,000,000 in gold was yielded by the placer diggings. His mother was a daughter of Maj. James R. Boyce, Sr., from Logan County, Ky., who had served under General Sterling Price of the Confederate Army. Major Boyce's ancestors were early settlers of the Old Dominion, and his grandfather had seen military service in the war for American independence. Major Boyce's mother was a descendant of the Marshall and Smith families of Westmoreland County, Va. When Thompson was eleven years old, the family moved to Butte, then a silver camp. He attended the public schools of Butte, but desiring a better education, entered Phillips Exeter Academy and later the Colum-bia School of Mines. Returning West, for a year or two he ran the Boulder Chief mine near Basin, Mont., which earned him a sobriquet, "Boulder Thompson." While here, some old ore sacks, oil-soaked, introduced him to flotation. He was also the first to leach some of the ore dumps of Butte.

Jan 4, 1928

At the University Club, New York, Jan. 23, Chairman George E. Hale and other officers of the National Research Council, gave a dinner to officers of the national engineering and other societies. About thirty persons were present, including officers of the National Research Council, the four Founder Societies, American Society for Testing Materials, Society of Automotive Engineers, Inc., Illuminating Engineering Society, United Engineering Society, and Engineering Foundation. Letters were received from the Western Society of Engineers, which also had been invited. Gano Dunn, vice-chairman of National Research Council, was toastmaster. The proposed permanent organization of the National Research Council and possible methods of connection with the national engineering societies, either directly or through Engineering Foundation, were outlined. It was suggested that not only the four Founder Societies be represented in the Engineering Division of National Research Council, but also that the other national engineering societies be admitted to membership. It was proposed that the Engineering Division should have a chairman who should be an engineer of wide reputation and of the highest professional attainments who should devote his whole time to the establishment and development of the Division. Methods of organizing industrial research were discussed. At a subsequent meeting of the National Research Council, an invitation was issued to each of the national societies to form a research committee encouraging that committee to become active in the promotion of research within its respective field. Due recognition is to be given each committee in the general organization of the National Research Council. Dr. H. M. Howe, in a very interesting and comprehensive address, told of much important work that had been clone by the various sections of the Research Council, as that of mechanical engineering in developing the often rather nebulous devices for helping win the war and putting them in such form that they could be of direct use to the military service. The section on metallurgy, till lately under Bradley Stoughton and now under G. H. Clevenger, did much valuable work in the improvement of helmets and body armor and made very extensive ballistic tests with refractory steels for this purpose. Important work was done in investigating the fatigue of metals and results of great moment were achieved. The committee on ferro-alloys, under J. E. Johnson, Jr., did important work in effecting economy of manganese in steel manufacture with a view to reducing the necessity for importation of manganese ore, thus releasing ships for other purposes. , The section on electric welding has accomplished valuable results in the development of electric welding for ships, a new branch of industry of very great promise.

Jan 3, 1919

By Coopers &. Lybrand

INTRODUCTION From a tax viewpoint, United States mining companies are at a substantial disadvantage in the international mining area compared with companies in other major capital-exporting countries, according to a 1975 study by Coopers & Lybrand for the American Mining Congress. The study compared the relative tax position of a United States investor with investors from Belgium, Canada, France, Germany, Japan, the Netherlands, Switzerland, and the United Kingdom. The comparison was based on average rates of return realizable by investor companies on four mine-model investments in twelve capital-importing countries. The countries in which these investments were assumed to be made are varied in their tax systems so that a wide range of possibilities was included in the analyses. Each mine model was standard so that the rates of return for each investment by each investor were affected solely by the respective tax systems of the capital-exporting and capital-importing countries. UNITED STATES POSITION The study found that the United States competitive position, in terms of the average rate of return on an overall basis, ranked next to last among the nine capital-exporting countries in the study. Further, the United States overall rate of return is more than 20% below that of the country (Japan) with the highest overall rate of return. On an average return-on-equity basis, the United States' position among the nine investor countries, for each of the mine investments studied, was: copper, eighth; iron ore, sixth; nickel, fifth; manganese, a tie for last place. Figure 1 shows the overall results realized by each capital-exporting country on the basis of average return on equity. [ ] The frequency with which a given capital-exporting country attains the highest or next highest rate of return in a capital-importing country provides further insight and another basis for comparing the tax laws of the capital-exporting countries. Of the situations compared in the study, the United States never attained the highest rate of return, and reached the second and third highest rate of return in only two instances. The tables showing the frequencies of rankings are given in Table 1 for each of the four mine models. In summary, the United States mining company does not have a competitive advantage under the tax rules when competing for mineral concessions in other countries. The United States company, in fact, appears to be at a clear disadvantage. The study also considered the effect of the following recent tax proposals on United States investors in international mining ventures:

Jan 1, 1985

By L. D. Jaffe, H. C. Mann, E. L. Reed

The authors have recently published1 evidence that brittle transgranular fracture of polycrystalline metals does not originate at a point and propagate continuously across the material, but rather develops at numerous related points, leading to a series of micro-cracks which subsequently link up. Series of related microcracks were observed in steel specimens broken in fatigue—specifically, at the central portions which broke during the final sudden fracture. Microcracks of the type mentioned have also been reported by Baeyertz, Craig and Bumps'2 in steel broken under impact. % Some micrographs published by Irwin3 may possibly be interpreted as showing discontinuous brittle cracks. This paper presents additional observations of the authors on discontinuous crack propagation under various conditions. Impact Test Specimens The impact test specimens were cut longitudinally from a steel forging containing: The heat treatment consisted of oil quenching in a heavy section from 1600°F and tempering at 1260°F. The resulting yield strength was 78,000 psi, tensile strength 100,000 psi, elongation 20.0 pet in 2 in., and reduction of area 55.0 pet. Standard V-notch Charpy specimens were broken in a 217 ft-lb machine at a striking velocity of 16.8 fps. Energy absorption and fracture appearance of this material in the V-notch Charpy test are plotted as functions of temperature in Fig 1. After test, fractured halves of specimens appearing 0, 40, 80, and 100 pet fibrous (to the unaided eye) were electroplated with nickel, sectioned longitudinally (perpendicular to the notch at its midpoint), polished and etched with Cohen-Hurlich-Jacobson (C-H-J) reagent (picric acid plus Zephiran chloride in ethyl ether)4 or with Vilella reagent (1 pet picric plus 5 pct hydrochloric acid in ethyl alcohol).5 Fig 2 and 3 show cracks near the path of final fracture in the specimen rated 0 pct fibrous. Many of the cracks terminate at the boundaries of ferrite grains, some at boundaries of pre- existing austenite gzains. * A crack often starts near the end of another. Cracks within the same ferrite grains are parallel or approximately parallel in several cases. A large percentage of the cracks are branched. Fig 4 illustrated a group of cracks in the 40 pct fibrous specimen. Branching and parallelism are well marked. No more than three directions of crack have been observed on the polished surface in one ferrite grain. This is consistent with the evidence6 that brittle fracture of ferrite takes place on the cube face crystallographic planes: the {100} planes. The appearance of some cracks suggests that they have passed around a projecting corner of a second ferrite grain by going outside the plane of polish. In Fig 5 cracks in the 80 pet fibrous specimen may be observed. Some of

Jan 1, 1950

By R. K. Matheson

THE Nivloc mine is 9 miles west of Silver Peak, Esmeralda County, Nevada. It has been operated by Desert Silver, Inc., since the summer of 1937. The cyanide mill treats 19o tons of silver-gold ore per day. In March of this year the main operations were about 2000 ft. west of the main shaft, which served as the downcast air passage for the mine. The mechanical blowers in use were sufficient to ventilate the west end at that time, but it was foreseen that as the mining area was extended ventilation would be an increasingly difficult problem, especially during the summer months. It was decided, therefore, to continue a raise from a point 100 ft. above the highest mining level (440-ft. level) to the surface; a distance of 443 ft. at approximately 65° From this point 40 ft. of drifting would be necessary to connect with a shallow shaft on the surface. (Fig. I.) All the raise was serviced from the 440-ft. level; costs and progress obtained in the initial 100 ft. are included in the following pages. CHOICE OF RAISE A raise in this locality would have four objects: (I) to provide an ample supply of fresh air to the working places; (2) to explore the vein from the highest mining level to the surface; (3) to provide waste fill for stopes in the area, and possibly provide a transfer for waste from the surface; (4) to provide an emergency exit in the west end of the mine. Before the mining of an ore shoot in the eastern part of the mine, a similar raise had been driven for purposes of ventilation and exploration. This raise and subsequent mining showed the vein to be noncommercial for a distance of about 250 ft. below the surface. However, in the area under operation, old surface workings showed occasional values. Thus from a development standpoint the raise was an excellent prospect. The raise chosen was a three-compartment, stulled raise having two chutes and a manway. The manway inside timber measured 4 ft. 8 in. by 4 ft. 6 in.; it carried air and water pipes, a ladderway and a slide for a timber skip. The two chutes would be used for drawing off the muck and the cleaning of the bulkhead, as well as for ore and waste passes, which would be especially useful for lateral exploration from the raise. The fairly large cross section of the raise (6 by 15 ft.) would provide a large quantity of waste for backfilling, and more could be obtained from a glory hole on the surface. TIME SCHEDULE As speed in completing the raise was the main requisite, three shifts were considered, but two shifts were decided upon when it was found that three would necessitate considerably larger fans than those available for clearing the raise. The main diffi-

Jan 1, 1942

By S. S. Cole, D. L. Armant

The smelting of titaniferous ores for the past hundred years has not been successful because of thickening of the slags in the furnaces. The interest in the utilization of these iron bearing materials has been due to the extensive deposits which have been found in various parts of the world.1 The literature contains references2 to the use of titaniferous ores in blast furnaces. None of these attempts has met with success due to the lack of sufficient information as to the cause of failures and to economic considerations. Evaluation of the published information, as to the probable cause of failure in various attempts, has indicated that the presence of lower valence titanium oxide and formation of titanium carbide contributed to the failure. It was apparent that severe reducing conditions which are present in a blast furnace had been one of the factors for such failures. The previous smelting operations had as a primary objective the recovery of iron from these ores. Under these conditions the highest recovery of iron could only occur with severe reducing conditions. Application of Melting Point Data The application of the melting point data, from the system CaO-MgO-Al2O3-TiO2 reported in another paper,3 to the smelting of titaniferous ores required an extrapolation of these melting points due to the presence of other impurities from the ores. Likewise, a study of the effect of varying FeO and reduced titanium content of the slag was necessary before the data could be fully applied. The melting point data under oxidizing conditions had clearly indicated that a fluid slag with a melting point in the temperature range of 1370°C could be obtained. The smelting of a titaniferous ore had as a primary objective the production of a high titanium slag which was fluid and substantially free of iron and low in trivalent titanium. Since production of a high titanium slag was of primary importance, rather than the recovery of iron from these ores, the smelting concept could be altered to a marked degree. The ferrous oxide could be maintained at higher levels than is the normal practice in iron ores slags without being detrimental to the slags, although a loss in iron recovery resulted. During the reduction of the molten mixtures of ferrous iron and titanium, carbon acts as the reductant for changing the valence of the titanium and iron. The reaction can go further than in the case of the reduction which occurs in iron-titanium solutions. The formation of metallic iron removes iron from the system, so that the titanium oxide can be reduced to trivalent and divalent titanium oxides and also form titanium carbide which removes the titanium from the slags as a soluble constituent. The problem, therefore, resolves itself into maintaining the proper amount of ferrous iron in the slag thereby avoiding the formation of appreciable amounts of trivalent titanium and no divalent titanium oxide or titanium carbide. The latter two have been found in the viscous

Jan 1, 1950

By T. Szaplonczay, D. E. Light

The auto-oxidation of sulfur dioxide to form sulfuric acid in commercially produced barren and recycle liquors, containing 1.66 and 4.56 gpl Fe respectively, from Elliot Lake was studied. A gas mixture, containing 3.5% SO2 and air was introduced into these liquors through a frit at a rate of 6.0g SO2 per hour per liter of solution. The barren and recycle were heated to 60°C. At the end of the first 24 hours of the process the concentrations of acid produced were 158 and 220 gpl H2SO4 for the barren and recycle respectively. Corresponding conversion efficiencies were 70 and 83%. In the period from 24 to 36 hours the rate of acid production decreased so that the H2SO4 concentrations at the end of 36 hours were 180 gpl for the barren and 260 gpl for the recycle; average conversions for the initial 36 hours were 55 and 68% respectively. Many investigators1'2'3 have considered the oxidation of sulfur dioxide to form sulfuric acid in aqueous solutions containing metallic ions. A summary of the work performed on this subject prior to 1946 has been presented by Keyes4 who described the auto-oxidation process as follows. Keyes also suggested that in this second reaction ferric ion serves as a catalyst for the conversion of sulfur dioxide to sulfuric acid. Neytzell-de Wilde and Taverner5 have reported on the use of auto-oxidation to produce a 4 to 5% sulfuric acid solution for use in a cyclic leach process at South African uranium plants. This paper describes investigations carried out to determine the feasibility of using the auto-oxidation process to produce sulfuric acid solutions of as high concentration as possible using commercially produced uranium plant barren and recycle liquors from the Elliot Lake region of Ontario. These liquors contained 1.66 and 4.56 gpl respectively of iron, chiefly in the ferrous state. This investigation is of particular interest to the uranium producers in Elliot Lake where the ores contain 3 to 4% sulfur, as sulfides. Flotation of these sulfides and roasting of same to produce SO, bearing gases have been successfully demonstrated using conventional methods.6'7 Barren and recycle solutions, as described previously, are also produced in large tonnages by these uranium producers. The experimental method and apparatus used to examine the auto-oxidation process will be described first. Then the tests carried out on laboratory prepared aqueous solutions containing ferric sulfate to determine optimum conditions will be presented. The next section will describe the tests using the commercial barren and recycle liquors. A final section will summarize the conclusions of the work. EXPERIMENTAL APPARATUS AND PROCEDURES Two types of solutions were used in the tests, a laboratory prepared aqueous solution containing definite amounts of ferric sulfate, and commercially produced iron bearing solution obtained from a uranium leaching plant in the Elliot Lake area. Two liters of a solution to be examined were placed in a 3 in. diam by 30 in. long glass cylinder with a cross-sectional area of 7 sq in. A mixture of air, and SO2 supplied from a lecture bottle for convenience, was introduced into the bottom of the vessel through a standard 30 mm glass frit, 700 sq mm in area. The temperature of the apparatus was controlled by a heating tape and variable transformer. Exhaust gases were vented to atmosphere. At the end of the test period the gas flow was shut off and the solution was analysed for H2SO4, Fe ++, and Fe +++, by conventional means. Four variables were examined using the laboratory prepared aqueous solution of ferric sulfate. First, the effect of SO2 concentration, from 1 to 1076, in the feed gas mixture was considered. Second, the temper-

Jan 1, 1964

By G. K. Manning, W. E. Few

T has been known for some time that both'inter-granular carbide and intergranular oxide phases cause brittleness in molybdenum. Parke and Ham' indicated that 0.0025 pct 0 present in molybdenum after solidification from the melt was sufficient to induce intergranular brittleness during forging. However, material containing 0.06 pct C could still be forged. However, adding this amount of carbon to insure deoxidation causes the formation of carbides on freezing. These carbides are precipitated at grain boundaries, and Rengstorff and Fischer' have shown they have an unfavorable effect on the room-temperature ductility of molybdenum. Take? in 1928 proposed that the solubility of carbon was a constant value of 0.30 pct from room temperature up to 1800°C. In 1935, Sykes, Van Horn, and Tucker' obtained X-ray data suggesting that the solid solubility of carbon in molybdenum was between 0.07 and 0.09 pct at temperatures from 1500" to 2100°C. The a-solubility line for carbon was included in the Mo-C diagram given in the Metals Handbook as a tentative line based on the data of Sykes, Van Horn, and Tucker. In order to determine the partial phase diagrams for these systems, it was necessary to construct a high-temperature furnace suitable for heat treating molybdenum at temperatures up to 4000°F. A molybdenum resistance furnace was built for this purpose in which samples could be heat treated in a purified atmosphere and quenched from any desired temperature.' Experimental Work Solubility of Carbon: Arc-cast molybdenum supplied by the Climax Molybdenum Co. and 18-gage molybdenum wire samples produced by powder metallurgy at the Fansteel Metallurgical Co. were used in determining the a-solubility line for the MO-C system. The cast molybdenum contained 0.032 pct C initially. Two lots of 18-gage wire were used, one containing 0.011 pct C and the other 0.005 pct C initially. All material contained a carbide phase as received. Fig. 1 illustrates the carbides found in the untreated material. Heat treatment in a purified hydrogen atmosphere was found to reduce the carbon content in the as-cast molybdenum. Purified argonT also decarburized molybdenum samples at temperatures above 3500°F; however, the carbon content remained constant during heat treatment in purified argon at lower tem- peratures. The argon was purified by passing it over titanium at 750 °C and then through a magnesium perchlorate drying tower. The hydrogen was purified by passing it through a commercial hydrogen deoxidizer, followed by a drying tower. Specimens having different initial carbon contents were heat treated in argon at 3500°F for periods ranging from 5 min to 5 hr and were analyzed for carbon. Samples of the same final carbon content had the same microstructures regardless of time at temperature. Furthermore, a gradient between center and surface in the amount of undissolved carbide particles present was never observed. It was concluded that at these low carbon levels, and at the high temperatures involved, diffusion proceeds so rapidly that the specimen is always substantially homogeneous in carbon content, in spite of the gradual loss in carbon. Based on the above findings, the following procedure was used to determine the carbon-solubility limit at 3000°, 3500°, and 4000°F. At each of these temperatures, a number of samples were heat treated, as shown in Table I, and rapidly cooled to room temperature. Since the samples lost carbon in proportion to the length of time heated, a series of samples were obtained of varying carbon contents. By use of a rapid cooling rate, the phases present at the high temperature were retained at room temperature. All samples were examined microscopically. Those found to contain either no excess carbide phase or only a very small amount were then analyzed for carbon. The samples actually analyzed for carbon

Jan 1, 1953

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