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By Walter Miller

During no similar period in the development of petroleum refining technology has so much progress been made in methods and equipment for the economical utilization of heat. Drastically severe commercial and economical conditions controlling the refining industry during 1927 gave a great impetus to improved efficiency and more economical operation in all departments. I think it is fair to say, however, that more progress has been made in the department of heat utilization than in other branches. I use the word utilization advisedly in the dual sense of better primary generation and application of heat and of saving by recovery methods. It was because of this trend that the subject, "Economical Application of Heat," was made the keynote of the refinery engineering sessions just completed. No new, outstanding elemental discoveries can be claimed for the year along this line. Some of the progress made has been in the development of better furnaces and distilling equipment embodying the more modern principles of boiler practice in obtaining complete combustion of the fuel, low excess air requirements and high transfer rates through the heating surface. Transfer rates of 3000 to 6000 B. t. u. per sq. ft. per hr. were considered good some time ago in the older type of equipment. Today a transfer rate of 25,000 to 35,000 B. t. u. is an actual accomplishment in commercial installations and engineers are talking of the feasibility of 50,000, 75,000, even 100,000 R. t. u. per sq. ft. per hr. Contributing most to bringing this about have been the rational use of the velocity factor on both the oil and firing side of the heating surface, and the study and application of the principles of radiant heat in furnace design. Vapor Heat Economy The principle of heat exchange, especially against oil vapors, has been applied to a greater extent than ever before. The recovery of heat from oil vapors is not new. This was practiced 20 years ago or more in Europe,

Jan 1, 1928

By B. C. Mariacher

EXTRACTION of uranium from ores is being ac-complished by processes which. for the most part, subject the entire ore to acid or carbonate leaching. Ore deposits with a U 3 O 8 content below 0.10 pct U 3 O 8 are seldom considered suitable for treatment by leaching. A preliminary concentration that would enrich the uranium content of an ore by a simple, low cost process based on physical properties of the ore might result in some low grade deposits becoming commercial ores. In addition, the process might be employed in existing operations to reduce transportation and leaching costs and to increase capacity of existing leaching plants. A study to attempt the development of a preliminary concentration process for primary uranium ores was undertaken by the Colorado School of Mines Research Foundation under sponsorship of the U.S. Atomic Energy Commission. The objective of this work was to produce concentrates containing 0.25 pct U3O8 from the low grade ores tested. Ores Tested: The main effort was devoted to the low grade primary uranium ores from northwestern Saskatchewan. Samples were obtained from the Beaverlodge operation of the Eldorado Mining & Refining Ltd. Additional primary ores, obtained from deposits in Gilpin County, Colo., contained from 0.07 to 0.10 pct U3O8. Summary of Concentration Tests: The Beaverlodge ore was tested to determine amenability of the ore to concentration by magnetic, electrostatic, gravity, and scrubbing processes. None of these produced satisfactory results. Both gravity and magnetic processes produced fairly good concentrates when closely sized fractions of the ore were treated, but on the basis of treating the total ore, recovery was poor. Preparation of sized fractions and the low capacity of equipment for suitable concentration made these methods impractical. As flotation offered the advantage of treating the total ore without intermediate sizing, the main effort was in this direction. A flotation process was developed that fulfilled the concentration objectives as set by the AEC. Pilot plant testing was used to verify results obtained from laboratory batch testing. Mineralogy: A petrographic examination of the Beaverlodge ore included a study of polished sur- faces and identification of the radioactive mineral by autoradiograph and X-ray diffraction. Approximate quantitative mineral identification was as follows: quartz, 60 pct; orthoclase feldspar, 20 pct; chlorite, 10 pct; carbonates, 5 pct; and miscellaneous minerals, 5 pct. Included in this last group were plagioclase feldspar, pyrite, mica, chalcopyrite, pyroxene, sericite, magnetite, galena, and uraninite. The most general occurrence of uraninite was in the form of crusts and thin coatings on limonite-stained grains of pyrite, quartz, and pyrite-quartz intergrowth. At least 90 pct of the uraninite was still attached to other minerals in a 100 by 200-mesh size fraction. The uraninite crusts were as small as 10 to 20 µ diam, and 5 to 10 µ thick. The Flotation Process Petrographic examinations of the Beaverlodge ore had indicated the impracticability of attempting to concentrate the uranium by floating individual grains of uraninite. Liberation of the uraninite required grinding to sizes below those suitable for flotation. However, there was preferential association of the uraninite with some minerals while others were free of uraninite attachment. The approach to the development of a flotation process was, therefore, based upon an attempt to concentrate the uraninite by floating carrier minerals. The following paragraphs discuss the various stages of the process with regard to the factors tested and the conditions under which best results were obtained. Grinding: The most effective size range for flotation was —150 mesh + 13 µ. The —13 µ material in the final concentrate had a higher U3O8 content than the total ore, but not as high as the average concentrate; however, rejection of slimes before flotation was prohibitive because of the loss in uranium carried in the —13 µ fraction. Grinding techniques which contributed to a minimum production of fines, such as stage grinding, were then employed. Quartz and Silicate Depression: These minerals represented approximately 80 pct of the ore and were free to a large degree of uraninite attachment. Significant improvement in the grade of the concentrate was obtained by depression of these minerals with hydrofluoric acid or sodium fluoride. Promoter: Selective stage flotation of uraninite carrier minerals was simplified by development of a single promoter mixture. The mixture consisted of an emulsion of a fatty acid, fuel oil, and a petroleum sulfonate and was selected after a comprehensive series of tests. It contained three parts by weight of an oleic and linoleic acid such as Emersol 300,

Jan 1, 1957

By G. A. Koehler

The Hiawatha mine, a producer of iron ore, is near the City of Iron River, in Iron County, Michigan. This mine, operated by The M. A. Hanna Co., has been chosen by the author as a typical iron mine in this district that is using the cut-and-fill mining system. General Geology The Hiawatha ore body lies along the steeply dipping north limb of a syncline that closes around on the east end to form a bathtub-shaped structure. Throughout this major structure there are very many smaller wrinkles or folds, which vary the direction as well as the thickness of the ore body. The total length of the ore formation with minor interruptions so far developed is about 3600 ft. The ore body throughout the entire present depth of 2000 ft. has averaged approximately 40 ft. in thickness; it is somewhat narrower at the upper levels and shows a marked increase in thickness on the bottom levels. This increase in thickness probably indicates that the bottom of the trough is near or that a major monoclinal fold has been encountered, which flattens the ore and gives apparent horizontal thickening. The footwall of this ore body is generally a black, graphitic slate, very rich in iron sulphides, quite combustible when exposed to air, and very treacherous to handle during mining operations. The hanging wall, in most places, is a cherty, fairly hard iron formation, and in general stands quite well ill open stopes. There are places, however, where black slate is found in both the hanging wall and the footwall, which makes mining difficult, as the black slate tends to slough off after being exposed to air. In these places it becomes necessary to leave a scale of ore 5 to 6 ft. thick on both hanging wall and footwall, which is not recovered. Fig. I shows a typical vertical cross section through the Hiawatha ore body. Type of Stoping Because of the size and shape of the ore body and the hard, dense structure of the ore, sublevel stoping has been an efficient and economical method of extracting the ore. This method, with various minor changes, has been used since the mine was opened in 1893. There have never been any stope-filling operations, however, until recent years, when crushing of pillars and black-slate fires forced the issue and methods were arrived at to fill all stopes. Development of Deeper Levels Shaft sinking to deeper levels in development operations has been done successfully by two methods without interference or hindrance to production. These systems are: I. Sinking an auxiliary winze a short distance from the shaft, then drifting back to the shaft location and putting up a pilot raise through to the bottom of the shaft. This raise is always in the manway compartment of the shaft, so that no work is ever done under a cage or skip. A 20-ft.

Jan 1, 1946

By Thomas T. Read

AT this time of the year, engineering schools are releasing a group of young men who probably are, on the average, in much the same attitude of mind as a person arriving at the terminal station of a railway journey; namely, of having a general idea of his objective, but having to make a decision as to just where he is going and how best to get there. The man leaving the train can at first follow the crowd, but it soon breaks up, as one goes one way and one another, until he has to choose his own course. The recent graduate may do the equivalent of following the crowd by accepting the first position offered, but this only postpones a decision as to where he is going and how best to get there. So many young engineers ask for advice as to what to do that the following statement has been prepared as an attempt to make a general answer to such queries. The engineer taking his first job should realize two fundamental relations. The first is that in electing to be an engineer he has elected to be a hired man. A consulting engineer has more freedom than a man on a regular pay roll, but he is also a hired man; hired for briefer periods at a relatively high rate, but under the necessity of simultaneously doing his consulting work and developing new retainers. There is nothing derogatory in being a hired man (all doctors, lawyers and clergymen are hired men), but the tardy realization that he is one seems to give many an engineer a mental jolt that can be avoided if he accepts it from the beginning.

Jan 1, 1926

By M. B. Ramachandra Roa

This paper records the results of the earth resistivity surveys made in the Godavari River in connection with the Ramapadasagar project. After describing the topographical and geological features of the area, the results of the investigation at the several sites have been mentioned. Further, a detailed account has been given of the resistivity methods adopted, the apparatus used and the interpretation of the curves. The resistivity measurements carried out over the water course have been specially outlined, and a review of the verification of the electrical indications by drilling in a number of cases, has also been presented. Introduction The Government of Madras has under consideration the Ramapadasagar project which is estimated to cost some Rs.660,-000,000 (about two hundred million dollars). The most essential feature of this project is the construction of a high dam across the Godavari near Polavaram for impounding the waters of this great river of South India, whose maximum discharge is 2 million cu secs in flood time. It is estimated that when the proposed reservoir is constructed, about one million tons of rice could be produced annually under irrigation. To those who have had any acquaintance at all with the recent distressing famine conditions which India has passed through and is still undergoing, the Lounteous effects which this project will bring about to the country in the future, are obvious. In the region of the proposed reservoir, the river flows for several miles through a hilly tract, hemmed in between flanks of hard, solid rock; but the river bed is mostly sandy. A few bore holes put down in this sandy bed touched rock at a depth of 180 to 200 ft. The river bed is about jo ft above the mean sea level (m.s.l.) and the bedrock was found at —125 to —160 ft m.s.l. The crest of the dam is proposed at +162 ft m.s.l. The proposed dam mould therefore be about 120 to 130 ft above the river bed, and the foundations would have to reach down nearly zoo ft below the bed at the deepest part. A number of alternative sites were proposed for investigation, and it became necessary to quickly ascertain the bedrock topography at these sites. Dr. M. S. Krishnan,* who was consulted in the matter, furnished a detailed account of the geological features of the region and suggested a geophysical investigation which the writer carried out from February to April 1944, employing solely the electrical resistivity methods. The total length of the survey lines for the electrical measurements amounted to 62,600 ft and the number of resistivity determinations was about 2500. Altogether nine alignments for the dam were inten-

Jan 1, 1949

By D. Mills, G. B. Craig

ZIRCONIUM has been float-zone-refined in an electron-beam furnace and the redistribution of oxygen, iron, and tungsten has been measured. The iodide zirconium used in the present experiments initially contained both oxygen and iron in the range 100 to 200 ppm by weight, and tungsten in amounts less than 10 ppm. Float-zone refining of zirconium, using induction heating, has previously been attempted by Kneip and Betterton1 and Langeron.2 Kneip and Betterton were primarily interested in the removal of iron and nickel. They achieved some purification, with respect to both these elements, in material given up to six passes at 150 mm per hr under an argon atmosphere. Langeron reported purification for a large number of elements after four completed passes in a static vacuum system operating at pressures less than 10-6 mm of Hg and with rates of zone travel between 30 and 40 mm per hr. He did not report oxygen concentrations, but stated that there was inverse segregation of this element. westlake5 has also used a minimum of four zone passes to remove iron from zirconium. No rates or conditions were given. Belk6 has shown that tungsten contamination can occur during electron-beam melting. He reported an increase from 0.01 to 0.05 pct by weight tungsten in molybdenum after four complete zone passes. The vacuum system for the electron-beam unit used in the present investigation consisted of a single-stage rotary pump backing a liquid-air-trapped oil-diffusion pump. A pressure of less than 10-8 mm of Hg was obtained with Dow-Corning 705 fluid in the diffusion pump. In order to avoid contamination of the zirconium by evaporation from the tungsten filament, a special focusing cage4 was employed. Three rates of zone travel, 114, 38, and 4 mm per hr, were investigated, with the liquid zone moving from the bottom to the top of the bar. The bars used were 3 mm diam and the total melted length was 130 mm. Oxygen was analyzed by neutron-activation analysis using a neutron flux of 10' neutrons per sq cm per sec to form the isotope N16 by the 016 (n,p) N16 reaction. The standard deviation is quoted for each oxygen determination. The iron and tungsten analyses were performed spectrographically, and the precision is estimated to be ±6 pct. Analyses for tungsten were all below the detectable limit of 10 ppm, confirming the protection given by the focusing cage. No significant redistribution of oxygen was found at the two higher rates of zone travel. The redistribution of oxygen and iron obtained after five passes at a rate of zone travel of 4 mm per hr (1.1 x 10-4 cm per sec) is recorded in Tables I and 11. Burris, Stockman, and Dillon3 have estimated the distribution of solutes during multipass zone refining. Using their curves for an effective distribution coefficient of Keff = 1.5 and 2 for oxygen and Keff = 0.3 for iron, the expected concentrations were estimated for the present material. These are shown in Tables I and 11, along with the experimentally measured values. The calculated concentrations are based on a molten-zone length of 10 pct of the total melted length, whereas in the present experiments the molten zone was approximately 5 pct of the total melted length. The effect of zone length on solute redistribution is most pronounced after a large number of zone passes. Comparison with Pfann's published data8 for solute redistribution for various Keff's and zone lengths indicates only small differences at low numbers of completed zone passes. It is evident that the expected distribution has not been realized in the case of iron. Scrapings of material deposited on the inner surfaces of the electron-focusing cage were found to be magnetic. It is, therefore, concluded that redistribution of iron is masked by evaporation. Deposition of iron inside the focusing cage was observed at all rates of zone travel. The results of the investigation may be summarized as follows: 1) Segregation of oxygen is typical for a solute with a distribution coefficient, Keff > 1. 2) No redistribution of oxygen takes place at high rates of zone travel. 3) The distribution coefficient for oxygen lies between 1.5 and 2.0. 4) Purification with respect to iron occurs mainly by evaporation. 5) The focusing cage is effective in preventing tungsten contamination.

Jan 1, 1967

By L. A. Walker

DURING the past twelve years the underground shaft of the United States mine at Bingham has been sunk an additional 2000 ft. with stations and pockets cut every 200 ft. without interrupting the mining of 600 tons of ore per day and the advancing of 1500 ft. of development per month. Following is a brief description of the way the joint work is conducted. The vertical underground shaft is a three-compartment shaft with outside dimensions of 6 ft. 4 in. by 15 ft. 6 in., and inside dimensions for each compartment of 4 ft. 2 in. by 4 ft. 8 in. The manway compartment of the main shaft is used as the hoisting compartment in sinking operations; it is partially lined with 2 by 12-in, lagging and a bucket is used without guides or crosshead. Preparatory work includes the placing of a bulkhead in the manway compartment, 60 ft. above the lowest station or level, the installation of a hoist, a head sheave, a fleet sheave, a-signal system, air and water lines, and a trap door for handling waste.

Jan 1, 1937

[A AALSETH Earl P (M 51) Consult Geol Engr 2019 Eldorado Dr, Billings, Mont ABADIE Henry G (M 43) Asst to. Supt of Oper Long Beach Oil Dev Co 925 Harbor Plaza, Long Beach 2, Calif. ABBET Waldo (A 56) Asst Diet Oper Supt Sun Oil Co P 0 Box 66, Stowelt, Tex ABBOTT Clifton T (A 60) Apartado 677, Maracaibo, Venezuela ABBOTT Fred E Jr (M 59) Abqaiq Diet Mgr Arabian American Oil Co Dhahran, Saudi Arabia ABBOTT J L (M 56) Partner Pritchard & Abbott 1010 Ft Worth Natl Bk Bldg, Fort Worth 2, Tex ABBOTT Richard H (J 51) Partner Abbott & Howard 422 W Hermosa, San Antonio 12, Tex ABBOTT William G (M 50) Div Mgr Rice Engrg &. Operating Inc Box 1142, Hobbs, N. M. ABDERHALDEN Ronald R (J 59) Prod Engr Continental Oil Co Box 100, Carml, 111]

Jan 1, 1961

By R. S. Wagner, W. C. Ellis

A new mechanism of crystal growth involving oapor, liquid, crnd solid phases explains many observations of the effect of implurities in crystal growth from the vapor. The role of the impuuitq is to form a liquid Solution with the crystalline tnalerial to be grown from the vapor. Since the solution is n prefevred site for deposition firorti the uapor, the liquid becorrles supersaturated. Crystal growth occurs by precipitatzon from the supersaturated liquid crt tlie solid-liquid zntevfnce. A crystalline defect, such as a screw dislocation, is not essetztial for VLS (vapor -liquid-solid) growth. The concept of the VLS mechanism is discussed in detail with reference to tire controlled growth of silicon crystals using gold, platinum, palladium, nickel, silver, or copper as an implurity agent. RECENTLY a short communication' described a new concept of crystal growth from the vapor, the VLS mechanism. In this paper we present a detailed description of the process and its application to the growth of silicon crystals and we discuss its relevance to existing concepts of .'whisker" crystal growth. Crystal growth from the vapor is usually explained by a theory proposed by Frank2 and developed in detail by Burton, Cabrera, and Frank.3 In this theory a screw dislocation terminating at the growth surface provides a self-perpetuating step. Accommodation of atoms at the step is energetically favorable, and is possible of much lower supersatu-ration than required for two-dimensional nucleation. Crystals of a unique form resulting from aniso-tropic growth from the vapor are "whisker" or filamentary ones. Such crystals have a lengthwise dimension orders of magnitude larger than those of the cross section. For most filamentary crystals both the fast-growth direction and directions of lateral growth have small Miller indices. The special growth form for a whisker crystal implies that the tip surface of the crystal must be a preferred growth site. sears4 proposed that, according to the Frank theory. a whisker contains a screw dislocation emergent at the growing tip. Such an axial defect provides a preferred growth site and accounts for unidirectional growth. The hypothesis was extended by Price. Vermilyea. and Webb," still implying the presence of a dislocation at the whisker tip. They postulated that impurities arriving at the fast-growing tip face become buried while those arriving on the surface of slow-growing lateral faces accumulate and thereby hinder growth. These considerations led to a whisker morphology. There is increasing evidence that most whisker crystals grown from the vapor are dislocation-free. Webb and his coworkers6 searched for an Eshelby twist7 in zinc? cadmium, iron. copper, silver, and palladium whisker crystals. They found unequivocal evidence for an axial screw dislocation in only one element, palladium. However, not every palladium crystal examined contained a dislocation. Observations with the electron microscope have failed to show dislocations in whisker crystals of zinc, silicon.9 and one morphology of AlN.10 Since many whiskers are completely free of dislocations, an axial dislocation does not appear to be required for whisker growth of many substances. A significant advance in understanding whisker growth has been a recognition of the need for impurities. This requirement has been clearly demonstrated for copper,11 iron,13 and silicon9-1 whiskers. For silicon, detailed studies proved conclusively that certain impurities, for example, nickel or gold, are essential. Another pertinent phenomenon which has received little attention is the presence of a liquid layer or droplets on the surface of some crystals growing from the vapor. Crystals in which this has been observed include p-toluidine,14 MoO3,15 ferrites,16 and silicon carbide.'" The liquid layers or globules were considered to be metastable phases, molecular complexes, or intermediate polymers originating from condensation of the vapor phase. The possibility has been suggested that the halide being reduced is condensed at the tip18 or adsorbed on the surface11 of a growing metal whisker, for example copper. The literature on whiskers discloses illustrations of rounded terminations at the tips. These appear. for example, on crystals of A12O3,19,20 sic,21 and BeO.22 For BeO, Edwards and Happel suggested that during growth of the whisker the rounded termination consisted of molten beryllium enclosed in a solid shell of BeO. A recent paper9 on the growth of silicon whiskers contains many observations pertinent to an understanding of the mechanisnl of whisker growth. These observations are summarized as follows. 1) Silicon whiskers are dislocation-free. 2) Certain impurities are essential for whisker growth. Without such impurities the silicon deposit is in the form of a film or consists of discrete polyhedral crystals.

Jan 1, 1965

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Jan 1, 1938

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Jan 1, 1938

WHEN one leaves the busy street and enters a library, the closing of the door behind him marks his passage into another world. Outside is the world of phenomena and appearances-of thronging pedestrians bustling about their business, of gregarious sights and sounds, of insistent auto-mobiles. Inside, on dusty shelves, is the stored learning of civilized man-the recorded ideas of countless generations. It is somewhat of a magic world. Here are the theories and secrets for which thousands of men toiled and gave their heart's blood. To produce one book on one phase of an ob-scure-subject may have required the best efforts of a group of men unique in their period. To prove one theory, or es-tablish a single application of a theory, may have taken the devotion of a genius who sacrificed his life to his work. This theory is perhaps stated in one paragraph of unassum-ing type, and the library contains millions of such para-

Jan 11, 1927

By James W. Lower

IN developing the orebody on lower levels of the Star mine at Burke, Idaho, Hecla Mining Co. is faced with a serious problem in driving raises. Levels are at 200-ft intervals. As a raise is being driven between levels, at points about 70 and 130 ft from the sill, heavy pressure arches develop and the raise becomes extremely hazardous. Eventually, following a blast, caving occurs, making it impossible to recover the raise. In February 1957 it was decided to attempt sinking a small winze on the vein from the 5500 to the 5700 level. This shaft (winze-raise No. 2) was to be used as a raise prior to stoping. It was assumed, and correctly, that the heavy ground pressure could be controlled by timbering close to the bottom after each advance.

Jan 7, 1958

By J. J. Frawley, W. J. Childs, W. R. Maurer

The object of this investigation was to determine the growth habit of bismuth and bisrrtuth alloy dendrites as a function of supercooling. To do this, techniques were developed to increase the amount of supercooling in bismuth and bismuth alloys. For pure bismuth, the growth habit was dependent on the amount of supercooling. At low amounts of supercooling, about 10" C, prismatic dendrites were obtained. With increased supercooling, about 20 C, a hopper growth habit was observed. In many cases where hopper growth had occurred, the hopper dendrites were twinned during the growth process. This twinned surface enable prismatic dendrites to nucleate and grow by a twin plane mechanism. When the amount of supercooling was increased to about 25 °C, the growth habit was a triplanar growth. With still greater supercooling, about 3s°C, a branched growth habit occurred. The exposed planes on the prismatic, hopper,, triplane, and branched dendrites have been determined. The growth habit of the dendrites which grew along the crucible wall was found to have the (111) as the exposed plane, with <211> growth direction. It is apparent that dendritic growth of a metal is dependent on its purity and the solidification variables present. One of the solidification variables is the degree of supercooling. Supercooling, although often observed, has not been studied extensively until recent years. For dendritic growth to occur in a pure metal, the metal must be thermally supercooled. After the dendrites grow into the supercooled melt, the heat of solidification raises the temperature of the specimen to the melting point of the material and the remaining liquid will solidify at this temperature. Decanting is the removal of this remaining liquid before complete solidification. This removal of the remaining liquid after recalescence had occurred is a great aid in the study of dendritic growth. In this investigation, decanting was accomplished by a vacuum-decanting technique . Other investigators1-5 have studied the growth characteristics of various low-melting-temperature pure metals and alloys as a function of supercooling. However, large degrees of supercooling were not included. For their study of dendritic growth of lead, Weinberg and chalmersl employed a decanting technique which was achieved by pouring off the remaining liquid, exposing the solid/liquid interface. This method was employed later by Weinberg and Chalmers2 for the investigation of tin and zinc dendrites. The method for obtaining a solid/liquid interface was improved by Chalmers and Elbaum. They employed a triggered spring which was attached to the solidifying section of the specimen. Upon activation, the spring jerked the solid interface away from the liquid melt. In the study of growth from the supercooled state, a metal of low melting point which exhibited a high degree of supercooling was desired. Bismuth gave very consistent supercooling when a stannous chloride flux was employed. The maximum supercooling obtained was 91°C, with an average supercooling of between 65" and 75°C. The consistency of supercooling greater than 50°C was very high. The use of vacuum to aid in the rapid decanting of molten metal has proven to be very successful in this investigation. The vacuum gives a rapid decantation, usually leaving the solidified metal structure sharply defined. The purpose of this investigation was to study the effects of supercooling and the effects of alloy additions on the growth habit of bismuth dendrites. The structure of bismuth has been variously defined as face-centered rhombohedral, primitive rhombohedral, and hexagonal. However, bismuth has only one plane with threefold symmetry, the (111) plane, and the crystal-lographic structure is considered a 3kn structure. MATERIALS The bismuth which was employed in this investigation was obtained from the American Smelting and Refining Co. of South Plainfield, N. J. The accompanying spectrographic analysis data indicated the bismuth to be 99.999+ pct pure. The tin was obtained from the Vulcan Materials Co., Vulcan Detinning Division, Sewaren, N. J. It was classified as "extra pure". Nominal analysis was 99.999+pct. In order to prevent contamination of the bismuth melt from the atmosphere, an anhydrous stannous chloride (Fisher certified reagent grade) was added to each melt. The fluxing action obtained from the use of the chloride provided a large amount of supercooling in the specimen. APPARATUS A 30-kw, 10,000-cps motor-generator set, connected to a 6+-in.-diam air induction coil, was employed to melt and superheat the specimens. The temperatures were recorded by means of a chromel-alumel thermocouple and a potentiometric recorder. The thermocouples were 0.003 in. in diam, and were encapsulated with Pyrex glass to prevent the thermocouple from acting as a nucleating agent and also from contaminating the melt. Fig. 1 illustrates the vacuum-decanting apparatus when a liquid flux was employed. A standard 30-ml Pyrex beaker was placed on top of an asbestos insulating block. A 5-mm-ID Pyrex tube with aA-in. spacer tip attached to its end was used for the decanting tube. The spacer tip contributed significantly to a successful decanting operation. The tip located the opening of the decanting tube about -^ in. from the bottom of the

Jan 1, 1969

By R. E. Boehler, N. C. Ludwig

At Buffington Station, Gary, Ind., Universal Atlas Cement operates fourteen 8 x 101/2 x 155-ft cement kilns in mill 6 and two 11 x 360-ft kilns in the Harbor plant. The No. 11 and 12 kilns in mill 6 are equipped with Manitowac recuperator sections. This report describes studies in measuring exterior shell temperatures on several of these kilns and the development of a traveling radiation pyrometer with certain novel features. Preliminary Work: At first various temperature-sensing devices were placed on the steel shell: 1) crayons with calibrated melting points, 2) colored paints with temperature-calibrated pigments, 3) aluminum paints with temperature-calibrated binders, and 4) metal-stem dial thermometers. The colored paints and aluminum paints failed to indicate the temperatures correctly. The crayons and thermometers did indicate fairly correct temperatures, but it proved impossible to apply enough of these on the shell to detect all the potential areas where hot spots might develop. Furthermore, considerable labor was required to apply these sensors and read the temperatures. Consequently no further work was done with these devices. Formation of Hot Spots: In the burning or clinker-ing zone of a cement kiln, the thickness of the protective coating and thickness of the brick govern the amount of heat transmitted to the steel kiln shell. Usually the protective coating consists of 4 to 8 in. of fused cement clinker. The formation of a hot spot is usually caused by loss of coating? that is, localized areas of the coating become thin or fall away from the refractory. This is generally caused by excessive temperature in the burning zone over a fairly long period of time. It may also be caused by a sudden thermal change in the burning zone. Variations in raw feed composition and in feed rate require changes in the fuel and air rates, and when these are not appropriately altered, conditions may develop in the kiln that will result in loss of coating. Luminescence on the kiln shell indicates that a hot spot has developed to a point that usually alters the refractory&apos;s thermal conductivity properties. When this thermal weakness zone occurs in the burning zone of the kiln, constant vigilance is required to protect it by maintaining proper coating. Even so, it has been the writers&apos; experience that within a period of several days to about four weeks the hot spot usually recurs with greater severity. This necessitates shutting down the kiln and re-bricking the affected area. One of the prerequisites of a good burnerman is the ability to maintain a protective coating despite the many variables in operation. When he knows that it is getting thin or that an area has dropped off, he reduces the firing rate and kiln speed and brings feed into the affected area in an effort to rebuild the coating. But when powdered fuel is burned, the atmosphere of the kiln may prevent the burnerman&apos;s observing the condition of the coating closely at all times without taking off the fire. It is not considered good practice to do this frequently, as it imposes a thermal shock on the coating and upsets operation of the kiln. To help the burnerman scan the shell of the kiln along the burning zone, therefore, a radiation pyrometer, connected to a potentiometric recorder, was mounted on a slowly moving steel cable. The theory of operation, construction details, and adaptability of the radiation pyrometer are included in an excellent monograph&apos; and also in a textbook.&apos; Shell temperatures of the Atlas Cement kilns were measured with a Brown Instruments Div. low intermediate range Radiamatic unit, of range 200" to 1200°F, and a circular chart Electronik potentio-metric recorder, of range 500" to 1000°F. In Bulletin 59095M the supplier publishes standard calibration data (millivolts vs degrees Fahrenheit) for this radiation pyrometer, These data, however, apply only to flat surfaces having emissivities of unity. Calibration of Radiation Pyrometer for Use on Curved Surfaces: When applied to surface temperature measurements, the radiation pyrometer reading depends on the nature of the surface, the material of which it is composed, and also to some extent on the temperature of the surroundings. Although the present radiation pyrometer is designed to give a calibrated response under ideal (black body) conditions when used commercially, it must be calibrated empirically. The calibration procedure, given below, follows that described by Dike (Ref. 1, pp. 38-39). Calibration tests on plane and curved surfaces showed that the response of the radiation pyrometer was very

Jan 1, 1961

By M. W. Cox, V. F. Hollister

Exploration for metallic mineral deposits is carried on by those special adaptations of methods which the explorer believes will yield most economically or satisfactorily the particular answer sought. In this project the usual methods of geologic observation, recording, and interpretation, when combined with magnetic geophysical methods and geochemical soil sampling, led to disclosures of appreciable zinc mineralization where none was visible in surface exposure. Since 1945 considerable work has been done with geochemical prospecting methods, chiefly in determining the presence and distribution of various elements existing in minor amounts in rocks, soil, vegetation or waters of mineralized areas. Such work, in which the U. S. Geological Survey has taken the lead, finds a ready place in the field repertoire of the exploration geologist as a supplement, not a substitute, for other methods. The Chollet project was carried out in 1951 by the American Smelting & Refining Co. near its Van Stone mine in northern Stevens County, Wash., in the area shown in Fig. 1

Oct 1, 1955

By Rees D. Rawlings, C. W. A. Newey

The aging characteristics of an Fe-11 at. pct Mo alloy have been studied by means of light metallography together with density, Young&apos;s modulus, and hardness measurements. The results were consistent with the precipitation of a single intermetallic compound during aging; overaging was slow relative to that in other iron-based binary alloys. The solution treatment temperature had a small effect on the rate of hardening whereas deformation prior to aging had a marked effect on both the rate of hardening and the peak hardness. The density data indicate that the compound precipitated is Fe3MO2 and not the Laves phase Fe2Mo. Analysis of the modulus and density results gave values for the time exponent for precipitate growth of approximately 1.0 and 1.5 for the alloy aged with and without prior deformation, respectively. DETAILED studies of precipitation hardening in bcc matrices have been confined largely to the effects of carbides and nitrides. In view of this and the growing technological interest in intermetallic compound strengthening, e.g., in maraging steels, a study of precipitation in iron-based alloys with a low interstitial content has been undertaken. This paper is concerned with the aging behavior of an Fe-11 at. pct Mo alloy; the mechanical behavior of the alloy will be reported later. The early work of sykes on Fe-Mo alloys showed that precipitation of the intermetallic compound was accompanied by an increase in hardness and a decrease in volume of the material. More recent surveys of the strengthening associated with precipitation have been made3-5 and, in particular, Elsen and wassermann4 showed that deformation prior to aging increased the rate of hardening. These latter workers also followed the precipitation process by means of dilatometry, electrical resistivity, and lattice parameter measurements. Their results confirmed that there is a decrease in volume on aging. Except for the work of Hornbogen on an Fe-20 at. pct Mo alloy, neither clustering nor the precipitation of a nonequilibrium phase has been observed in Fe-Mo alloys. Studies of alloys of lower molybdenum content475 indicate that the equilibrium intermetallic compound is precipitated during aging. However, there is some doubt concerning the nature of the equilibrium precipitate phase. According to the phase diagram constructed by Hansen,8 the phase should be precipitated. This phase has a rhombohedra1 crystal structure which is characterized by the formula Fe706,&apos; although the composition of the molybdenum-rich boundary corresponds approximately to Fe3Mo2. The version of the diagram proposed by Sinha, Buckley, and Hume-Rother indicates that the A phase, a Laves phase Fe2Mo, should be precipitated. Their observation of a Laves phase supports the earlier findings of Bechtoldt and Vacher,13 although, in a recent study of the system by means of diffusion couples, Rawlings and Newey did not detect the phase. The work presented here describes the effect of solution-treatment temperature, aging temperature, and prior deformation on the aging characteristics of the alloy as revealed by light metallography together with hardness, density, and Young&apos;s modulus measurements. In addition the density data are used in an attempt to determine the compound precipitated during aging. EXPERIMENTAL PROCEDURE A 29-kg ingot of the alloy was cast at R.A.R.D.E., Fort Halstead, from deoxidized, Japanese electrolytic iron and sintered molybdenum. The ingot was homogenized for 6 hr at 1473°K and then worked, with intermediate anneals, into 6- and 16-mm-diam rods and 6-mm plate. Chemical analysis of the alloy gave, wt pct: Mo, 17.5 (11 at. pct); C, 0.003; Si, 0.002; S, 0.005; P, <0.002; and02, 0.0098. Solution treatments were carried out under a dynamic argon atmosphere in a vertical, "crusilite" element, furnace which had a facility for rapid quenching into iced water. Except for the study of the effect of solution treatment temperature, all specimens were solution-treated at 1573" * 2°K for 1 hr. Salt baths were used for the aging treatments. Specimens for hardness, density, and Young&apos;s modulus measurements were produced, after heat treatment, from the stock rod or bar using a precision silicon carbide slitting wheel. As described later, the quenching treatment produced local plastic strain in the stock material; consequently, care was taken to ensure that the specimens were not prepared from these regions. Those specimens used in the studies of the effects of prior deformation on the aging behavior were strained in compression in a Denison universal testing machine. Specimens for light metallographic observations were mechanically polished on successively finer grades of diamond paste down to and then etched in either alcoholic ferric chloride or in a 2 pct nital solution. Vickers diamond pyramid hardness data were obtained using a 30-kg load. At least five impressions were averaged for each determination. Density measurements were made using a displacement technique in which each specimen was weighed in air and in dibromoethane at 296°K. The specimens were cylindrical and weighed 3 to 4 g; all weighings were made on a balance reading to 1 x 10"5 g. For each specimen the mean value of five weighings was used to calculate the density. The density of the dibromoethane was determined using the displacement procedure and a standard nickel specimen. The error in an absolute density value was estimated to be HI.01 pct. To obtain the density as a function of aging time a single specimen was used and the density meas-

Jan 1, 1969

F. E. BACHMAN, Port Henry, N. Y. (written discussion*).-Experi-ments with titaniferous ores found in Essex County, New York, made by the MacIntyre Iron Co. in 1914, showed&apos; that titaniferous concentrates are reduced in the furnace with no greater, and probably with less, expenditure of heat, and consequently of fuel, than non-titaniferous mag-netites; and as a greater proportion of their oxygen is removed by carbon monoxide than is the case with non-titaniferous magnetites, a lower fuel consumption for the reduction of iron may be expected. After the furnace was blown out at the end of the experiment, the formation in the hearth was found to be abnormal. The brickwork was replaced, entirely around the furnace, by a layer which at -the tuyere circle was made up of cinder, fine carbon, and coke; the coke, however, gradually disappeared toward the bottom, being replaced by cinder and graphite. The usual salamander of graphite and iron was missing. The material left in the hearth seemed to be cinder that had not drained from the last cast; its composition, though, would indicate that it was in the furnace previous to the taking off of the titaniferous ore. At first, this material was thought to be blast-furnace cinder mixed with less iron and graphite than is normal; but an examination showed it to be made up of cinder with small masses of iron and graphite. There were also patches of a steel-gray material having a metallic luster; a microscope showed these patches to be made up of black metallic crystals interlacing white crystals.

Jan 11, 1919

By C. E. Lawall

ONE of the most important developments in the coal industry during 1940 was the continued uptrend in the production of bituminous coal. Estimated production for the year is 450,000,000 tons, with an additional production of anthracite of 50,000,000 tons making a total of approximately 500,000,000 tons. This is an increase of 12.5 per cent over 1939. Despite an estimated decrease of about 3.5 per cent in anthracite production, all of the major coal-producing states had increases in production for 9140. The national defense program, with the consequent increase in industrial activity, undoubtedly had an important effect on the increased demand for coal.

Jan 1, 1941

By C. F. Cigliana

TO accommodate a large tonnage at high speed from a single level at San Manuel, a very flexible haulage system was designed to give maximum access to stoping areas, minimize delays, and pro- vide for safety. With these requirements as a guide, the haulage was laid out as a simple double loop with one-way traffic of continuous pull. These loops consist of two parallel drifts 100 ft apart, center to center. Haulage drifts are numbered from north to south, the northernmost being the No. 1 drift. This holds true on both the North and South haulage loops. Haulage drifts are connected at 1000-ft intervals with crossovers so that it is possible to bypass any given section that may be inaccessible. Two of these turnouts are double diamonds, one located on the approach to the rotary dumps at the hoisting shafts and the other on the departure from the dumps. The turnout on the approach or North haulage is 835 ft in front of the rotary dump, and the one on the departure, or South haulage, is 1058 ft from the dump. This type of turnout allows trains coming down either haulage drift No. 1 or No. 2 to be routed into either shaft and expedites movement by avoiding delays due to congestion in the dumping area. The double diamond on the return haulage loop facilitates returning empty ore trains to the panels.

Jan 5, 1958