Search Documents

By E. A. Gulbransen, W. S. Wysong

THE behavior of tungsten and its surface oxides in oxidizing and reducing atmospheres and in high vacua at elevated temperatures is a question of considerable technical importance. The use of tungsten as a metal or as an important component in alloys in high temperature oxidizing atmospheres has been limited because of the unprotective nature of its oxide film and the volatility of its oxide. This paper will present results of a microbalance study1,2 of the following problems: (I) the oxidation behavior in the temperature range of 25 to 550°C (2) the reduction with pure hydrogen of thin oxide films formed on tungsten, and (3) the volatility of thin oxide films on tungsten. Tungsten is an interesting metal to study for the following reasons: (1) although the oxide to metal volume ratio is greater than one, the oxide is not considered protective, (2) the metal readily oxidizes at temperatures from 300° to 550°C (3) the oxides W02 and WO3 are reduced at temperatures as low as 500°C. by hydrogen, and (4) the oxide W02 is volatile at temperatures from 800 to 1100°C. LITERATURE The oxidation of tungsten in its thin film range has not been studied critically. In the thick film range Dunn3 has made the only systematic study. He found the oxidation rate to obey the parabolic rate law in the temperature range of 700 to 900°C. The temperature variation of the oxidation rate constant was found to follow an exponential law of the Arrhenius type. An inflection was noticed in the temperature plot of the rate law constant at 850 to 900°C. This was attributed to a phase change in the oxides. Scheil4 has studied the oxidation rate at 500 and 700°C over long periods of time and found a linear rate law. This result was interpreted as evidence for the presence of a nonprotective film. Pilling and Bedworth5 analyses of the oxide volume to metal volume ratio would indicate that a compact protective film should form. McAdam and Geil6 have studied the oxidation of tungsten in the thin film range using the interference color method. A parabolic rate law was found. Their curves showed that tungsten oxidizes faster than nickel but more slowly than iron. The lattice structures found in the oxidation of tungsten surfaces have been studied by Hickman and Gulbransen.7 They have reported that W03 is the stable oxide in contact with the metallic substrate up to approximately 600°C while W02 forms first at 700°C. Hägg and Magneli8 have recently reported a study of the lattice structures observed in the tungsten oxides using the X-ray diffraction method. In addition to an a-phase W03 and a d-phase W02, they reported the existence of two new phases. A ß' phase, homogeneous between

Jan 1, 1947

By F. L. Bosqui

INTRODUCTION The history of the development of gold metallurgy in South Africa is divisible into two periods: That preceding the introduction of the cyanide process on a commercial scale in 1890; and the 24 years intervening between that important event and the present time. The period between the discovery of the banket reefs of the Witwatersrand and the year 1890 was one of phenomenally rapid progress in mining development, but of no special interest to the metallurgist. There were no strikingly original or distinctly local advances in the treatment of gold ores. Californian practice in stamp milling and amalgamation prevailed, in mills ranging in equipment between 5 and 50 stamps, operating within a wide range of efficiency, and under the trying conditions usually en¬countered in a new and isolated field. The somewhat incomplete records of gold output of that period show that in December, 1887, there were 20 producing companies in the Witwatersrand district, of which 10 had mills, the largest being of 20 stamps. The only official record of returns for May, 1887, was that of the Wemmer mine, whose modest achievement with a 5-stamp, mill was 100 tons crushed, producing 887 oz. 3 dwt. of gold. This is interesting in view of the .present-day output of this field, which in 1913 reached 8,430,998 oz. The rapid increase of production during this first period (May, 1887, to January, 1891) is shown by the following summary for the year 1890:1 Total tons crushed 702,828 Number of stamps in operation 1,046 Average number of tons crushed per stamp per day 2.36 Yield of gold, ounces 494,817 Yield per ton, pennyweights 13.36 The stamp duty ranged between 1 ½ and 4 tons per day, according to weight of stamp, fineness of screen, and operating skill available. The prevailing weight of stamp was about 900 lb., and the screen, 900 meshes to the square inch.

Jan 5, 1915

By John Hays Hammond

The Transvaal comprises about 120,000 square miles (nearly • the size of the United States Territory of New Mexico). Besides the famous Witwatersrand, which will here be de scribed in detail, there are two quartz-mining districts of some importance, viz., Lydenburg and De Kaap. The Lydenburg district first attracted attention in 1876, when the alluvial deposits of that section began to be exploited. At a later period vein-rnining was started, and at the present time several companies are operating in that district. The product in 1898 of five companies, running 137 stamps, was 154,560 tons of ore, yielding 108,884 crude ounces of gold (an average of 14.09 dwt. crude gold per ton) valued at £392,378. The De Eaap gold-fields were discovered in 1884. In 1898, seven companies, running 200 stamps, produced 89,760 crude ounces of gold, valued at £314,792. I. Mining Titles in the Transvaal. The mining laws of the Tranuvaal are most excellent in char acter, and while the claims cover every square foot of land for an area of nearly 40 miles long by from 2 to 3- miles wide, there have been practically no conflicts over extra-lateral rights. Notwithstanding the change in the political status of the Transvaal likely to follow the present war, it may be coufi dently assumed that the main features of the mining law of the South African Republic will be retained, and certain op pressive featureu of monopolies, etc., bearing with special weight on the mining industry, will be abolished. The dynamite mo nopoly was one that bore most heavily on the mining industry; and, according to the Reports of the State Mining Engineer, explosives, including fuse and detonators, amounted to nearly 10 per cent. of the total working costs of the mines. Further more, it was impossible to obtain the proper quality for the most economical working, and often 80-per-cent. or 40-per-cent. gelatine had to be used- in many instances where 60-per-cent.

Jan 1, 1902

By Walter S. McKee

When mixed with common cast steel in quantities ranging from 11 to 131/2 per cent. and properly treated, manganese increases the ductility of the metal and adds greatly to its toughness and resistance to abrasive action, which properties comprise the distinctive characteristics that make manganese steel so valuable for many purposes at the present time.. * At present the manganese-steel foundries of this country have an annual capacity of about 60,000 tons and most of the growth has occurred within the past 10 years. In the early days of the industry it was impracticable to make manganese castings weighing over a few thousand pounds, but at present crusher heads, rolling-mill pinions, and similar castings weighing up to 30,000 Ib. each are produced, and it does not appear that the limit of weight has been reached by a considerable margin. Manganese steel is similar in analysis to ordinary first-class converter metal except that it is high in carbon and contains from 11 to 13.5 per cent. of manganese. From one standpoint manganese steel is similar to malleable iron in that the casting as it comes out of the sand is hard and brittle and must be made ductile by a heat-treating process. The heat treatment is an essential part of the process of making manganese-steel castings and must be properly carried out to secure satisfactory results. The necessity for heat treatment limits the thickness of sections which may be made of manganese steel. Originally the annealing depth was comparatively small, but researches carried on during the past few years have resulted in an increase in the thickness of section up to 51/2 in., which it is possible to treat successfully. Large castings are cored out to a minimum thickness of 51/2 in., thus not only eliminating some of the internal stresses which are invariably set up in a very thick casting, but also reducing the weight and inertia of the piece, an important consideration if the casting is to be a moving part in a machine. At the same time, the thickness of 51/2 in. is sufficient to permit the use of manganese steel for the heaviest classes of machinery.

Jan 1, 1916

By J. D. Runkie, A. G. Lyle, G. A. Gillies

Tar evaluation of data obtained by selective flotation from even a simple ore is a very difficult process, and when the ore tested is complex the process becomes extremely difficult and cumbersome The authors, in the course of an investigation into the selective behavior of various flotation reagents on nonmetallic minerals§ were confronted with an aggravated form of this difficulty, owing to the large mass of data that had accumulated over a period of years They finally devised a method whereby the results of the various flotation tests could be correlated and interpreted by means of graphs representing recoveries and rejections of the component minerals in the ore This method of graphical analysis proved so useful in nonmetallic flotation that it was afterwards applied to sulphide flotation, where it yielded equally satisfactory results Since this method of analysis leads to very definite conclusions as to the effect of changes in reagents and flotation procedure, it is felt that a wider application of the method might assist the industry by reducing the amount of test work required, and possibly increase the accuracy of the final analysis GRAPHS In Fig I, four curves are plotted on the same graph with cumulative percentages as ordinates and cumulative weights as abscissas In this instance the four curves are named, respectively the barite-recovery curve, the limestone-rejection curve, the silica-rejection curve, and the summation curve In these tests barite was the mineral concentrated, therefore a barite concentrate was produced Definitions Before explaining the curves in detail it might be advisable to define several new terms, such as "percentage rejection," "summation index," and "summation curve," as well as the word "test," which has been used in a special sense. A "test" will include all the operations performed upon a batch of ore from the time it is placed in the rod mill until the last product has been assayed Thus a test may be a comparatively simple procedure producing only one concentrate and a tailing, or it may be a very complicated procedure producing five or more concentrates of a specific mineral as well as a tailing The number of concentrates produced will depend entirely upon whether the collector was added to the pulp in the flotation cell in one lot or was added in five or more portions Percentage Rejection-The ability of a selective flotation collector to reject an undesired mineral is just as important as its ability to collect the desired mineral The percentage rejection curves shown on the graphs give this factor due consideration and its value is calculated as follows Suppose a concentrate contains 5 per cent of an undesired mineral This indicates

Jan 1, 1942

By John L. Watson

A conceptual model (MAGSEP) is described to simulate the beneficiation characteristics of a drum magnetic separator in terms of the probability of an individual grain being recovered in the magnetic concentrate. This probability is determined as a function of particle magnetic composition and magnetic field strength and is modified by particle size and the separator operating conditions. The model predicts the size, magnetic grade and distributions of magnetic and gangue minerals in the concentrate and tailings produced by the drum separator. The configuration of the magnetic concentration circuit may be altered to permit single or double drum units in parallel or series operation. The characteristics of the feed material, in terms of a magnetic parameter, are essential in permitting the determination of individual grain recovery probabilities upon which the model is based. Thus the model requires input data relating to the distribution of composite grains in terms of magnetic grade and particle size. To illustrate the use of the conceptual model an example is given for the beneficiation of New Zealand iron sands.

Jan 1, 1984

By K. Osseo-Asare

The presence of carbonaceous matter in gold ores presents a two-fold problem: (1) The poor release of gold from the carbonaceous matrix and (2) the uptake of dissolved gold by the carbonaceous leach residues. A critical review is presented of the published information from various parts of the world pertaining to the nature of the carbon-containing components of these ores and their different roles in the gold extraction process. Included in this paper are new results based on the authors' research on carbonaceous ores from the Prestea goldfields of Ghana. Methods for isolating and characterizing the carbon-containing materials are given and a discussion is presented of the interaction of the carbonaceous ores as well as the fractionated components with aurocyanide solutions. Emphasis is on basic physico-chemical phenomena, investigated with the aid of X-ray diffraction, infrared spectroscopy, adsorption, and electrophoretic mobility studies.

Jan 1, 1984

By W. E. D. Jr. Stokes

THE application of aviation to mining and petroleum operations, on the basis of economy and attainment, has become a demonstrated fact. According to Dominion Government records, 30. Canadian companies engaged in air transportation with northland mining camps, carried 13,000 tons of freight in 1935, and in 1936 carried 16,000 tons. In addition, many mining companies used planes to transport prospectors with canoes, outboard motors, gasoline drums and supplies to remote locations, and one company maintained a plane to take radium-bearing ore from its mine on Great Bear Lake nearly 1000 miles south to the rail-way at Waterways, Alberta. Heavy pieces of mining machinery weighing 2 tons are being carried by Ford trimotor planes over the Andes, at an altitude of not less than 15,000 feet. At Bulolo, New Guinea, 17,500 tons of disassembled gold-dredging equipment has been flown over inaccessible terrain, while supplies and building materials for a, community of 1000 whites have been transported by airplane. A 3 1/2-ton shaft was carried on one notable trip, while at another time an automobile, 2 tons of rice and a large safe went over the mountains in one plane. Fig. 1 shows an electric generator that was carried by plane to Bulolo.

Jan 1, 1937

By T. Watanabe, S. Karashima, H. Oikawa

Creep tests of a! iron and its solid-solution Fe-Mo, Fe-Co, and Fe-Si alloys with bcc structure were conducted under constant stresses in ferromagnetic and paramagnetic temperature regions above 0.5T,(T, is the absolute melting temperature). It was found their high-temperature creep behavior changed in the vicinity of the magnetic transformation temperature, that is Curie temperature, TC. In the ferromagnetic region below the steady-state creep rates were lower than those expected from the extrapolation of the data in the paramagnetic region, the amount of decrease being affected by solute addition. Also, activation energies for steady-state creep were different in the two temperature regions. The observed changes were concluded to be due to the effect of ferromagnetism on diffusion. It is well-known that plastic deformation of metals and alloys in the temperature region where mobility of atoms becomes high enough is controlled by atomic diffusion." Many experimental results394 on fcc and hcp materials have been reported to confirm this view. In bcc metals and alloys, not much basic investigation of creep deformation has been performed. In particular, experimental work on iron5-&apos; and its alloys, covering a quite wide temperature range is extremely scarce. On the other hand, the effect of ferromagnetism on diffusion has recently been demonstrated in a iron and its alloys;&apos; it has been made clear that diffusion rates in ferromagnetic temperatur~e region are significantly lower than those expected from diffusion measurement in the paramagnetic region. Therefore, it is concluded that the magnetic effect influences the high-temperature creep behavior in a! iron and in its alloys. The present authors have conducted creep experiments on a iron and its solid-solution alloys over a very wide temperature range, and have demonstrated the magnetic effect. A part of the result has already been reported elsewhere.26 In this paper, the experimental results will be described in detail. While the manuscript was in preparation, a similar magnetic effect on creep deformation of a iron was reported by Ishida . Though their experiments covered an extremely wide temperature range, the creep stresses varied from several thousand psi to several ten thousand psi with decreasing temperature. Consequently, it may be said that there remain some questions concerning their results. I) EXPERIMENTAL PROCEDURE The materials used in the experiments were pure iron and its alloys; they were prepared by vacuum melting (10"" mm Hg) electrolytic iron (99.9 pct), molybdenum powder (99.9 pct), ultrapure silicon, and cobalt pellet (99.5 pct) in alumina crucibles. The ingots were hot-forged to plates 10 mm thick and 50 mm wide, and then were hot-rolled at about 700°C into sheets 1 mm thick. Creep specimens, 5 mm in width and 15 mm in gage length, were machined from the sheets. They were annealed at temperatures which were well above their respective recrystallization temperatures. The chemical compositions of the metal and alloys are shown in Table I together with their heat treatments. High-temperature creep tests by the use of a lever-type creep testing machine were carried out in argon atmosphere under constant tensile stress. In order to keep &eep stress constant within about *0.5 pct, stress change due to specimen elongation was compensated by tensile force of a stainless-steel bellows which was inserted between the loading lever and lower specimen grip with the assumptions of a linear relationship between change in cross section and strain and uniform strain along the section. Beyond the limit of compensation by the bellows, small amounts of load were removed after appropriate strains. The testing temperatures were maintained to within i2"C of the reported values. Creep deformation was auto-graphically recorded at the upper (moving) specimen grip using a linear differential transformer which was held by a stainless-steel rod mechanically connected to the lower specimen grip. It was also directly measured with a dial-gage reading to -& mm. 11) EXPERIMENTAL RESULTS AND DISCUSSION 1) Creep Curves of a Iron and Its Alloys. Creep curves of a! iron, Fe-Si, Fe-Co, and Fe-Mo (<2 at. pct Mo) alloys usually consisted of three stages, that is transient (primary), steady-state (secondary), and accelerating (tertiary) stages. An example is illustrated in Fig. 1 for a! iron. However, in Fe-Mo alloys with more than 2 at. pct Mo, an inverse transient creepZ8 was observed as indicated in Fig. 2. The inverse behavior, which varied with the amount of molybdenum, may be due to the substructure* in the annealed specimen as was sug-

Jan 1, 1969

Albin, B. R Billings, Mont. &apos;28 Amster, Nathan L 25 Broad St., New York, N. Y. &apos;28 Bache, Jules S 42 Broadway, New York, N. Y. &apos;28 Barrett, C. P 5338 Harper Ave., Chicago, 111. &apos;28 Bayless, William S Russ Bldg., San Francisco, Cal. &apos;28 Bean, Louis, H 60 E. 42nd St., New York, N. Y. &apos;28 Beatty, Ross J Room 604, 6 N. Clark St., Chicago, III. &apos;28 Benwell, Oswald F Hold Mags. &apos;28 Beymer, Albert S., V.P., Keystone National Bank Pittsburgh, Pa. &apos;28 Blumenthal, Hugo 44 Pine St., New York, N. Y. &apos;28 Boettcher. Charles Ideal Cement Bldg., Denver, Colo. &apos;28 Bowlus, Thomas H., Banker, Pres., Allen County State Bank Iola, Ran. &apos;28 Brown, Colvin B Chamber of Commerce, Washington, D. C. &apos;28 Burt, Maxwell Struthers Southern Pines, N. C. &apos;28

Jan 1, 1934

By D. S. Tomalin, D. F. Stein

The effect of reducing oxygen to low concentrations on the fracture of high-purity iron single crystals has been examined at 78° and 20°K. It is found that iron single crystals grown by the strain-anneal method usually contain a few occluded grain boundaries which may become embittled in the presence of oxygen, thereby nucleating cleavage fractures. High purity with respect to interstitial elements was found to inhibit twinning and evidence is presented for an orientation dependence of the resolved yield stress. Deformation occurred by slip rather than twinning at both temperatures of testing with elongations of as much as 9 pct at 20°K. THE fracture properties of iron single crystals have been observedl-3 to be a function of temperature, orientation, and purity. Allen, Hopkins, and McLennan1 demonstrated that at 78°K iron single crystals became increasingly brittle as the tensile axis approached the (001) pole of the stereographic unit triangle. Iron crystals with the tension axis near a (001) pole were completely brittle and orientations near the (011)-(111) boundary were very ductile, achieving a 100 pct reduction in area prior to fracture. Later work of Biggs and pratt2 and of Edmondson3 demonstrated that by reducing the carbon content of the single crystals the transition between brittle and ductile failure at 78°K could be shifted to orientations nearer the (001) pole. Ed-mondson went further and pointed out that any mechanism which tended to increase the yield strength of the iron (i.e., carbon addition, pre-strain) also increased the tendency for brittle behavior at 78°K. Thus by a reduction of carbon content Biggs and Pratt were able to obtain ductile behavior to within 20 deg of the (001) pole, and Ed-mondson was able to obtain ductile behavior to within 26 deg of the (001) pole. Edmondson&apos;s material had a total interstitial content (carbon, oxygen, and nitrogen) of approximately 60 ppm and, although Biggs and Pratt reported no analysis, indications were that their iron contained comparable impurities. Stein, Low, and seybolt4 purified iron single crystals to a total carbon, oxygen, and nitrogen content of approximately 20 ppm. They observed a lowering of the yield stress with this increased purity, and thus one might have expected an observation of increased ductility. Although they tested specimens of orientations which the previous workers had indicated should be ductile, the crystals failed at a 78°K in a brittle manner with little elongation. Stein noted,&apos; however, that about 90 pet of the failures could be traced in origin to occluded grains. Allen et al.1 and Edmondson3 do not report examination of their cleavage surfaces, but Biggs and pratt2 reported that microscopic examination of the cleavage surfaces of many of their specimens revealed the presence of small occluded grains. Honda and cohen6 and Keh7 have also observed the initiation of fracture at occluded grains in iron single crystals. Therefore, the additional complication of occluded grains must be considered in studying the properties of iron single crystals and the origin of fractures determined if the ductility exhibited by the crystals is to be considered meaningful. Various investigators8-12 have studied the effects of impurities on grain boundaries in high-purity polycrystalline iron. Rees and Hopkins10 showed that the addition of oxygen to low-carbon (0.002 pet) iron weakened the grain boundaries, causing a shift from transcrystalline to intercrystalline fracture and a progressive decrease on the brittle-fracture stress with increasing oxygen content. In addition, it has been shown by Low and Feustel11 that the addition of carbon to polycrystalline iron containing oxygen eliminated grain boundary brittleness. Thus, oxygen can embrittle grain boundaries in high-purity polycrystalline iron, but the addition of an appropriate amount of carbon can eliminate the oxygen-induced brittleness. The oxygen content (19 ppm) of the iron "single crystals" employed by Stein el al. was large enough to suspect impurity effects at the occluded grain boundaries. Allen et al.1 Biggs and pratt,2 and Edmondson3 may have masked any occluded grain problem in their specimens considering the relatively high carbon levels they employed. stein13 demonstrated that the addition of as little as 0.9 ppm C to previously purified (less than 5 x 10-3 ppm C) "single crystals" would increase the elongation from a few percent to more than 20 pet at 78°K and the fracture was not associated with grade boundary initiation.

Jan 1, 1965

By D. J. Weintritt, R. G. Hughes

Statistics show arz increase in the average depth of wells drilled in recent years. As a corollary to this trend, drilling fluids have been improved in an effort to meet the problems inherent at temperatures approaching 500°F. Of importance are (1) deterioration of mud components and (2) the effect of solids on filtration and rheological properties. High-temperature, stable water-base and oil-bare muds are discussed. Those areas in which differences exist are pointed out. Results are based on data taken from the Fann consistotneter, rheometer and shear-strength measurements, static and dynamic filtration tests, methy-lene blue test for bentonite solids and specific heat measLrrenlents of muds. INTRODUCTION Higher well temperatures go along with the fact that the average depth of wells continues to increase. Recent data by Gardner&apos; lists 137 completions deeper than 15,000 ft for the first half of 1964 with a record second-half total of 167 wells drilling or proposed. In addition, there has been an increase in drilling for steam for power production or mineral recovery. In this application the depths are modest, but the mud may approach the critical pressure and temperature of water. Scearce and Magnon&apos; report drilling mud used at temperatures of about 700°F in the Salton Sea area of California. Most deep wells have been drilled with water-base muds. In recent years, however, there has been a substantial increase in the use of oil-base muds because of technological advances in effective additives. The significance of this development was dealt with in considerable detail by Simpson and his co-workers.3 Additiona1 field data have now been obtained to indicate that oil muds are competitive in control, performance and cost with the best types of water muds for use at high temperaturc. This parallel offer of two very different fluid systems, each offering a similar variability in performance, cost and convenience, has created the need to evaluate the merits of these fluids under specified conditions so that the advantages and disadvantages of each can be weighed in relation to the over-all drilling program. This paper is not intended as a review of all the factors. Rather, it attempts to emphasize: (1) important condltions and facts peculiar to high-temperature drilling muds, (2) that more than one imposed test condition or testing method is necessary to describe the quality of a mud at high temperature and (3) that elaborate experimental precautions are necessary whenever laboratory data are used in selection of a mud for field use. WHAT IS A HIGH-TEMPERATURE DRILLING FLUID? For the purpose of this discussion, a high-temperature drilling fluid is any system so formulated or treated to economically minimize the effects of temperature on the properties of the fluid. Our experience in drilling fluids suggests that these effects become obvious for many mud materials at temperatures of 300F or higher. It is understood that hydrolysis of starches, depoly-merization of certain organic thinners, or irreversible chemical reactions (such as that of clay and lime) can affect filtration, viscosity and shear strength at less than 300F. However, the temperature level is not a serious point and in no way affects the precautions and techniques used in this study. An up-to-date review of the literature on high-temperature drilling fluids and the many variations was treated by Rogers&apos;in 1963. EXPERIMENTAL REQUIREMENTS TESTING EQUIPMENT AND PROCEDURES With the advent of deeper drilling and increased demand for temperature-stable drilling fluids, new testing equipment and laboratory techniques were devised for the evaluation of drilling fluids subjected to elevated temperature and pressure. While the equipment has not been standardized, it is in widespread use. Milligan et al. Qescribe a filtration cell for determining the filtration properties of drilling fluids at temperatures in excess of 300F. They showed the effect of variations in temperature and pressure on oil and water muds filtered in the 300 to 400F range. The dynamic filtration apparatus described by Simpson6 permits the study of the filtration properties to temperatures of 350F for drilling fluids circulated over sandstone cores. Watkins et al.&apos; describe the use of pressure bombs for studying the effect of prolonged periods of elevated temperature upon the gelation or solidification of drilling fluids. Chisholm et a1.&apos; describe the use of a modified cement consistometer adapted for use in drilling fluid evaluations. A similar consistometer is used in this study, although the application and data-recording method have been changed. The consistency of a mud sample is measured by timing the movement of a soft iron bob which is magnetically moved up and down in the sample container.* Changer in the time of travel and the temperature of the mud at that moment are plotted with a two-point Brown Elec-tronik Recorder. A 10-in. chart with a speed of 4-in./hr is used. Fia.- 1 is a generalized internretation of the data ob-

Jan 1, 1966

By Oliver C. Ralston

A definite field of usefulness has developed for the brine-leaching processes of removing lead from ores and other products, so this paper reviews the developments, both in practice and in research, that have taken place since the publication of two earlier papers on this subject.&apos; Several commercial plants are now in operation and a number of semi-commercial test plants have been operated in an effort to determine the limitations of brine leaching and to compare the results with other forms of treatment. Briefly, the brine leaching of lead depends on the fact that lead chloride and lead sulfate are soluble in saturated sodium-chloride solutions. In dilute brines, the solubility of the lead salt is less than in pure water; but in the strong brines, the solubility is greater than in pure water due, supposedly, to the formation of a double sodium-lead chloride. This is seen in Fig. 1, which shows the results of M. Demassieux2 on the solubility of lead chloride in sodium-chloride solutions of different concentrations and at three temperatures. The curves are not those given by Demassieux but are calculated from his results in order to convert them to units common in metallurgical work. The right-hand branch of each curve shows that if the solution is kept in contact with solid sodium chloride the lead chloride can be almost entirely displaced from solution, but that brines which are saturated with sodium chloride, but are not in contact with the solid salt, have a very high solubility for lead chloride. The diagram gives the analysis of the solution in grams of lead per liter, although the substance actually in solution is lead chloride. At 100" C. as much as 100 gm. of lead per liter can be obtained; but at lower tem-

Jan 1, 1924

By Clyde E. Williams, V. N. Krivobok, C. H. Herty

THE extreme effect of the depression on the steel industry is well illustrated by the fact that the amount of iron ore shipped from the Lake Superior district was the lowest in 47 years. Something over 3 1/2 million tons of ore was shipped in 1932, compared with over 65 million tons in 1929. It is not surprising then that practically no advancement in iron ore beneficiation has been made. Improved research and development work, however, was continued at the Michigan College of Mines in the survey of the lean iron ores of Michigan with reference to the possibility of their concentration; at the University of Minnesota in its large-scale jigging studies of Lake :Superior ores; and at Battelle Memorial Institute in the development of improved jigging of iron ores. The successful operation of the new Hadsel mill at a gold property in California gave such low grinding costs on a quartz ore as to give much encouragement in the iron ore industry for a cheapening of the cost of grinding lean ores for concentration.

Jan 1, 1933

By W. P. Sykes

SEVEN years ago, Dr. S. L. Hoyt1 presented a masterful discussion of the hard metal carbides and cemented tungsten carbide. His lecture summarized most of the data then available in the field; many of the details relating to the production, properties and structure of cemented tungsten carbide had never been previously published, for, in fact, this information was only then being acquired. During the intervening years, the cemented carbides have assumed a place of real importance in the commercial field, with an ever widening variety of applications due to constant improvement in the control of production technique and the unremitting search for new compositions that might better the performance of the alloys in one or another type of service. The most recent summary of production methods, properties and guides for the successful application of the cemented carbides appears in the 1936 edition of the Metals Handbook. Of necessity, much detailed information relating to structures and physical properties is not included in such a summary, and it is with such details that the present discussion is concerned.

Jan 1, 1938

By George S. Koch

Since 1882, world zinc production has increased. In contrast, US zinc production rose until about 1915, but since then has remained nearly constant, with a slight tendency to decrease. Production from the Tri-State district, the largest early source of zinc in the US, has gone down steadily; this decline has been balanced by a growth in the rate of other districts. These changes in US production are due to economic, not geological, factors. Recent exploration has located large minable ore bodies: additional deposits will undoubtedly be found in the stratabound carbonate rock and volcanogenic environments. A statistical analysis of the exploration effort in the Middle Tennessee district indicates that new discoveries can be expected there. Thus, the US is in an early stage of the production cycle for zinc. Of major mining districts in the US, only the Tri-State is exhausted under current economic conditions; large zinc resources of low-grade material, which would repay mining at higher prices or improved technology, are known to exist in that district .

Jan 1, 1982

LIST OF THE MEETINGS OF THE INSTITUTE AND THEIR LOCALITIES FROM ITS ORGANIZATION Transactions Number Place Date Vol Page I Wilkes-Barre, Pa * May, 1871 I 3 II Bethlehem, Pa August, 1871 I 10 III Troy, N Y November, 1871 I 13 IV Philadelphia, Pa February, 1872 I 17 V New York, N Y * May, 1872 I 20 VI Pittsburg, Pa October, 1872 I 25 VII Boston, Mass February, 1873 I 28 VIII Philadelphia, Pa * May, 1873 II 3 IX Easton, Pa October, 1873 II 7 X New York, N Y February, 1874 II 11 XI St Louis, Mo * May, 1874 III 3 XII Hazleton, Pa October, 1874 III 8 XIII New Haven, Conn February, 1875 III 15 XIV Dover, N J * May, 1875 IV 3 XV Cleveland, 0 October, 1875 IV 9 XVI Washington, D C February, 1876 IV 8 XVII Philadelphia, Pat June, 1876, V XVIII Philadelphia, Pa October, 1876 V 9 XIX New York, N Y February, 1877 v 27 XX Wilkes-Barre, Pa * May, 1877 vi 3 XXI Amenia, N Y October, 1877 vi 10

Jan 1, 1910

By James P. Roe

I. INTRODUCTION. THOSE who deem the subject of this paper an old and super¬seded one may recall with advantage the words of the great proverb-maker, bidding us to seek the new in the ashes of the old. The manufacture of wrought-iron began with the small hearth built upon an eminence, and relying on the wind for blast. Next came, either the hearth about 12 in. in diameter by 2 ft. in height, blown by a man operating two goat-skins for bellows, or, a hearth of greatly varying diameter and about 10 ft. high, depending for its blast upon natural draft. The former appeared in India, the latter in Burmah; and both were in operation until quite recently, though their origin is lost in prehistoric times. The Catalan forge was the evolutionary descendant of the foregoing, and the parent of the Blase-ofen, which in turn led to the high bloomary or " Stückofen," the father of the blast-furnace, as a producer of cast-iron. The production of cast-iron checked the growth of the direct processes; and led to the introduction of various hearths, such as the Walloon, for low-silicon irons; and the South Wales process, combining the run-out fire with the finery, for higher-silicon irons. Some of these are still in operation in localities possessing the necessary raw materials; and their product is used for purposes requiring wrought-iron of exceptional quality, the supply of which is still smaller than the demand. We have to look back but a century and a quarter to see the introduction of the puddling process by Henry Cort; a process which, reinforced by the iron-oxide bottoms and fettling of Hall, was not less revolutionary in character, and more revo-

Jul 1, 1905

By C. S. Simons

Manufacturers of filtering, thickening or clarifying equipment, have been active in developing machines to meet increasingly rigid operator requirements, and the innovations resulting from this effort are moving into commercial applications. In general, the results of these applications are reported to be good. Little has been reported on progress in theory. The growing insistence on the part of pollution control agencies that waste water discharged into streams contain less and less suspended solids is being felt by a broad cross section of industry. A new clarifier, based on the often rediscovered fact that suspended solids settle more rapidly in inclined channels, is being marketed by Neptune MicroFLOC of Corvallis, Ore. This unit employs modules of inclined tubes, mounted in the upper zone of the clarifier, which carry the water flow. These were developed for light solids, such as those encountered in domestic water treatment and in paper mill waste water. In these applications, flow rates up to about three times those permissible in conventional clarifiers are reported to give comparable overflow turbidity. By combining these units with mixed media filters, high clarity may be obtained with minimum capital. Use of such units in the metallurgical industry, particularly where water reuse or effluent quality is important, should grow.

Jan 1, 1970

By AIME AIME

THE Tuesday afternoon session", H. A. Bedworth chairman and T. S. Fuller, vice-chairman, was opened with D. J. McAdam, Jr.&apos;s paper entitled "The Influence of Cyclic Stress on Corrosion." This paper dealt with the influence of cyclic stress on corrosion of alloy steels, corrosion-resisting steels, monel metal and aluminum alloys. The paper was discussed by T. S. Fuller, who pointed out that steels under stress corroded more than unstressed steels when subjected to steam.

Jan 1, 1930