Search Documents

By C. P. Karr

FOR several years, the Bureau of Standards has been working in cooperation with an Advisory Committee on non-ferrous metals on various phases of the production and testing of zinc bronzes. The work has dealt, especially with the type of metal known as "Admiralty bronze" in England and as "Government bronze" in this country and consisting of 88 copper, 10 tin, and 2 zinc. Several reports have been made on this subject and these should be considered in connection with this paper.1 FIRST SERIES OF FIVE FOUNDRY TESTS A very brief summary of the first series of five foundry tests has been made,2 but for the sake of clearness the results are given here in different form. The five foundries cooperating in this investigation were: Ohio Brass Co., Mansfield, Ohio; Titanium Alloy Mfg. Co., Niagara Falls, N. Y.; Packard Motor Car Co., Syracuse, N. Y.; National Cash Register Co., Dayton, Ohio; Bureau of Standards, Washington, D. C. The object of the work was to determine whether uniform results could be obtained with this alloy in different foundries working under definite instructions. One of the participating foundries prepared, from virgin metal, a stock of ingots of the composition 88 copper, 10 tin, 2 zinc, and at the same time poured nine test bars from this melt of virgin metal. The results of the physical tests of these bars are shown in Table 1. Examination of this table shows that the highest and most nearly uniform results were obtained when the virgin metal was cast flat in chill molds and the lowest and most variable results were encountered when it was cast vertical in green-sand molds. In this, as in all other tables, the mean

Jan 9, 1919

By John Griffen

THEORY HYDRAULIC classification as explained by Rittinger and others was largely restricted to conditions wherein the free-falling velocities of the particles were conceived as governing the separations effected (see chapter 9). The laws governing classification under free-falling conditions have been summarized by Chapman and Mott as follows: 1 Nomenclature r represents, in a particle of irregular shape, the round-hole screen through which the particle would pass, or some other linear dimen¬sion of the particle equivalent to d, the diameter of a sphere. s, the specific gravity of the particle. 1, the specific gravity of the water used as a medium. K, a constant. W, the velocity of the water. In an Upward Current of Water 1. A particle will move upward if [W > KVr(s-1)] and, by suitably regulating the speed of the water current, the larger and heavier particles may be made to fall downward against the current, leaving the smaller, lighter particles in suspension in the current. 2. Particles such that [T1= s2-1] cannot be separated in an upward-current classifier with any one velocity of current. Coal particles having a specific gravity of 1.35 cannot be separated from refuse particles of 2.5 sp. gr. Unless 2.5-1 the ratio of diameters is less than [1.35-1 or 4.3 to 1,] and the raw coal must be screened to size limits within this ratio if they are to be separated. Cone¬-shaped vessels or vessels of other shapes that allow the use of&apos; different velocities of current at different points in the flow are used to modify this limitation. 3. During the initial stages of motion, coal particles ascend more rapidly than refuse particles of the same size. 4. A particle will ultimately fall if [W < KVr(s-1).] If particles of

Jan 1, 1950

By G. Nabi, W-K. Lu

Cylindrical specimens of natural dense hematite were reduced to magnetite at atmospheric pressure in H2-H2O mixtures of known composition over the temperature range 1084° to 1284°K. The rate of reduction was measured by the rate of movement of the interface between hematite and magnetite. The diffusion of gases through the gaseous boundary layer, the magnetite layer, and the interfacial chemical reaction were all considered in the interpretation of experimental data. The mass transfer coefficient through the boundary layer was calculated using accepted correlations. Values of the chemical reaction rate constant and the diffusivity of hydrogen in the magnetite phase were determined. THE present investigation is concerned with the reduction kinetics of natural hematite to magnetite by H2-H2O mixtures in the temperature range 1084" to 1284°K at atmospheric pressure. This reaction is the first step in the series of topochemical reactions in the process of reducing hematite to iron. Kinetic information of the simple steps such as hematite-magnetite transformation is necessary in order to have a better understanding of the complex processes of hematite reduction in iron-making. It also has direct industrial significance because magnetic roasting is one of the most important methods in benefication of lean ore.&apos; Although many technical papers have been published on the process of magnetic roasting and iron oxide reduction, very little information is available in the literature concerning the fundamental nature of hematite reduction to magnetite by reducing gases. Hansen et al.2 reduced the dense synthetic pellets of high-purity oxide in CO-CO2 mixtures and determined the reaction rate by weight-loss method. They were able to interpret most of their results by applying the interfacial area control theory developed by Mckewan.3 In contrast, Wilhelm and St. Pierre,4 who studied reduction of hematite to magnetite in H2-H2O mixtures by weight-loss method, stressed that the resistance of the porous magnetite layer to the diffusion of gases cannot be neglected in consideration of the overall reaction rate. In the present study the contributions of interfacial chemical reaction, diffusion of gases through the magnetite phase, and the gaseous boundary layer to the overall reaction rate will be considered. APPARATUS AND PROCEDURE Hematite Specimens Preparation. Natural hematite ore from Vermillon range of Northern Minnesota was selected for the present investigation because of its high purity and thermal stability. Chemical analysis of five samples gave the following average values: 67.52 pct total iron (96.62 pct Fe2O3, 0.28 pct FeO, 0.03 pct metallic iron), 2.53 pct SiO2, <0.07 pct MgO, 0.03 pct CaO, 0.05 pct combined mixture, 0.07 pct loss on ignition, and 0.34 pct other. Cylindrical specimens of 0.93 cm in diam and 2.7 cm in length were drilled from slabs of ore with a water-cooled diamond core drill. These specimens were heated to 1000°C and furnace-cooled. Specimens with silica pockets developed large cracks. The uncracked specimens were heated a second time, and their surfaces were carefully examined with a microscope. Those with hairline cracks or surface inhomoaenitv-- were rejected. Preparation of H2-H2O Mixtures. H2-H2O mixtures were prepared by the combustion of H2-O2, mixtures in a pyrex glass chamber in the presence of a catalyst. Alumina pellets coated with palladium, supplied by Englehard Industries, were used as the catalyst. Purified grades of hydrogen and oxygen were used which were repurified by usual techniques. Hydrogen before entering the combustion chamber was passed through an activated alumina H2O absorption bulb, with copper turning at the top. The cover of this bulb was not made pressure-tight so that any pressure development in the hydrogen line would cause the cover to blow off and also the copper turnings would act as a flame arrester in the case of a flashback from the combustion flame. Oxygen flow rates were measured with a bubble flow meter after purification with 1 pct accuracy. Hydrogen flow rates were measured by "precision wet test meter" and the amount of unburnt hydrogen was accurately measured by a bubble flow meter, after condensing water vapor in the gaseous stream. The Pyrex glass bulb contained concentric Vycor glass tubes as shown in Fig. 1. Oxygen was prevented from diffusing into the hydrogen line by threading platinum wire through pores at the combustion end of gas inlet tube. The glass bulb was heated with a Kanthal heating wire pasted in asbestos paper. The surface temperature of the bulb was measured with a thermocouple and adjusted to remain at approximately 350°C. The gaseous reaction chamber also served as a preheater for gases to avoid thermal segregation. The following sequence of operation was adopted. 1) Nitrogen was passed through the outer concentric tube to purge the catalyst bulb of oxygen. 2) Hydrogen was introduced through the inner tube until a steady flow was obtained. 3) Oxygen was then introduced into the nitrogen stream passing through the outer tube. 4) When combustion had commenced and a flame was visible over the platinum wire, the N2 was turned off.

Jan 1, 1969

By W. R. Ingalls

IN THE years immediately preceding 1914, the American people earned an aggregate income of 33 to 34 billion dollars, of which they saved about five billion, the annual saving being expressed mainly in the form of houses and railway extensions; to a less extent in public utilities, public improvements, factories and mines; and to a very small extent in foreign investments. It appeared needful that we should save and invest annually in these ways about 15 per cent. of our aggregate income in order to keep the development of our plant, so to speak, ahead of our steadily growing needs. The common knowledge that at present our housing and railway facilities are inadequate suggests immedi-ately that we have been running behind the pre-war ratio of reinvestment. Since 1919, we have not had any carefully prepared, authoritative estimates of the national annual income. However, with some experience in this subject, I have ventured to make rough estimates, which rest on solid foundations, although some rather empirical develop-ments are involved. Such estimates would be consid-ered good work in this field if they fell within limits of 10 per cent., plus or minus. Even so, these data are more useful when quickly available than more accurate data that are belated; for recognizing that there is a margin of error we can at least get a reasonable and approximate idea of how things are going.

Jan 2, 1923

By D. C. McLean, S. A. McKay

The purpose of this paper is threefold: 1) to describe actual ground control installations made at the various mines of the International Nickel Co. (Canada) Ltd mines in Sudbury, Ont. during a planned test program. 2) to suggest new ground control techniques which are now possible by the use of fully grouted bolts 3) to indicate the possible economic advantages to be gained by the use of resins and resin grouted bolts to control difficult ground conditions. Were a theme selected for this paper it would be: "Preserve the original roof in best condition possible by the use of smooth blasting techniques and fully grouted roof bolts — since the original rock is the best and cheapest material available for ground support." TYPES OF BONDED BOLTS As has been shown previously, there are several ways in which a bolt may be bonded. These are illustrated in Fig. 1 and 2. There are three general types of grouted bolts: 1) pretensioned, 2) post-tensioned, and 3) untensioned. The type which will be of most benefit to the user will depend upon the particular ground support problem involved. Despite the many arguments propounded for the necessity for using a tensioned bolt, ample evidence exists from actual experience that untensioned bolts can be effective in many instances. The outstanding characteristic of a grouted bolt is that it provides the user with a variety of rock consolidation techniques heretofore unavailable with conventional rock bolts. Many of the unusual characteristics of grouted reinforcing bar have been evaluated by researchers in the concrete structure field.&apos; Underground application has largely been pioneered in the construction field, with especially good work being reported from the Snowy Mountains Hydroelectric Authority in Australia. Techniques developed there using cement grouted bolts are now being adapted in many large government construction projects in this country with excellent results. The ap- plications described in this paper are those in which Cyanamid&apos;s Roc Loc Mining Kits were used exclusively. SLUSHER DRIFTS AND FINGER RAISES (BOX HOLE BROWS, DASHES) A common mining problem especially where block caving methods are applied is that of maintaining the roof in slusher trenches particularly at the intersections of the trench with the feed raises (box holes) through which the large fragments of broken ore tumble. Typical sections are shown in Fig. 3 and 4. In Fig. 3, the drift is normally driven 7 ft wide by 8 ft high initially. The rock involved is a hard norite (diabase) which is usually competent but has "block cleavage". This roof has a tendency to fall out in large blocks when subjected to operating stresses. Depending upon the initial condition of the roof, the drift is either lined with 2 to 3 ft of concrete immedi-

Jan 1, 1964

By C. W. Goodale

THE motives behind the organization of the Bureau of Safety were twofold. First, there was the policy of the company toward its employees, which was one of fairness and consideration for their welfare and which entails the prevention of injuries; second, in order to prevent injuries, a study of their causes was essential, and this study could be made only by a thorough systematic classification of accidents, which required a special department to form and carry out the plans. The Bureau of Safety was organized to begin operation Jan. 1, 1914, but practically all of the first year was spent in collecting data, making plans, etc. This department is semi-independent of others and reports directly to the president and general manager. It consists of the president of the company and the managers of the following departments: Mines, Washoe Reduction Works, Great Falls Reduction Works, Coal Department, Lumber Department, B. A. & P. railway, and the chairman of the Bureau of Safety. Working under this group is the General Safety Committee consisting of the manager of mines, as chairman, the general superintendent, two assistant general superintendents, and the heads of the following departments: mechanical, geological, purchasing, sampling works, and framing plant, as well as the safety engineer. Operating under the General Safety Committee are the group safety committees, consisting of the Anaconda group of mines, Boston & Montana group of mines, zinc group of mines,.Washoe reduction works at Anaconda, B. & M. reduction works at Great Falls, coal department, lumber department and the B. A. & P. railway. Each of these group safety committees was in charge of the superintendent or manager of the group represented and the committee consisted of the foremen of the mines or works that the committee served, as well as the safety engineer.

Jan 2, 1922

By E. A. Gulbransen, K. F. Andrew

The gas-metal reactions of zirconium are very interesting. The metal is extremely stable at room temperature to reactions with the several gases present in air and the metal will stay bright indefinitely. However, at temperatures of several hundred degrees higher the metal reacts readily with oxygen, nitrogen and hydrogen. This behavior, in addition to the fact that zirconium is one of the higher melting point metals which might have high temperature applications under the proper conditions, resulted in the work reported in this communication. There are several factors which indicate that zirconium might have good oxidation resistance at elevated temperatures. These are: (1) the high melting point of approximately 1860°C, (2) the high melting point of the oxide of approximately 2675°C, (3) the high degree of thermodynamic stability of the oxide to chemical reaction and the low decomposition pressure of the oxide and (4) the possible formation of a continuous oxide film since the volume ratio of oxide to metal is greater than unity. The unfavorable factors are: (1) the metal reacts to form nitrides, hydrides and carbides, (2) the oxide is soluble at elevated temperatures in the metal and (3) the oxide ZrO2 undergoes crystal structure transformations at high temperature. The oxidation resistance of this metal is not only a question of the rate of film formation but is complicated by the fact that the oxide and other reaction products dissolve in the metal which in turn will affect the physical and mechanical properties of the metal. The protection of the metal to nitride formation must be considered separately from the oxide problem. One unfavorable factor is that the volume ratio of the nitride to the metal is about unity. This indicates that a discontinuous film might be formed. This paper will present measurements on the rates of reaction of the metal with O2, H2 and N2 over a wide temperature and pressure range. The reaction in high vacuum and the stability of the several compounds formed will be presented. The results are correlated with fundamental rate theory and with the physical and chemical structure of the metal and film. Literature Although many papers have been published on the chemical reactions of zirconium with various gases, comparatively few are concerned with the protective nature of the metal and its reactions at normal pressures. The studies in the pressure range below 0.01 mm of Hg gas pressure are largely of interest in the nature of the adsorption of gases by hot filaments in high vacuum apparatus. The reactions of zirconium in this pressure range have been reviewed by Fast8 and by RaynOr.27 In spite of certain differences of opinion as to the maximum adsorption temperatures for various gases, the low pressure range is qualitatively understood. Some of these papers will be mentioned briefly here. 1. LOW PRESSURE Ehrke and Slack&apos; find that oxygen reacts above 885°C and hydrogen above 760°C. Nitrogen does not react up to a temperature of 1527°C. Fast9 on the other hand observes that oxygen is absorbed above 700°C and nitrogen at temperatures exceeding 1000°C. Hydrogen is absorbed from 300" to 400°C and liberated between 500" and 800°C. It is readsorbed at 862°C and released above 862°C. Hukagawa and Nambo22 find a rather complicated picture for the absorption of oxygen. A rapid initial absorption is found between 180" to 230°C. Further oxygen is not taken up until a temperature of 450°C is reached. The optimum temperature for complete absorption is 650" to 700°C. Nitrogen is found to be completely adsorbed at 600°C. However some of the gas is evolved at higher temperatures. Their data on the absorption of hydrogen indicate some of the gas is removed at 550°C. Guldner and Wooten17 in a study of the low pressure reactions of zirconium with various gases observed that the reaction with oxygen occurs at temperatures above 400°C and that the oxide is formed. The reactions with carbon monoxide and carbon dioxide occur rapidly at temperatures of about 800°C with the oxide and carbide being formed. Zirconium reacts at temperatures of 400°C slowly and at 800°C rapidly to form the nitride and with hydrogen and water at 300°C to form the hydride and a mixture of the oxide and hydride respectively. 2. NORMAL PRESSURE DeBoer and Fast3 in a study of the electrolysis of oxygen in zirconium find that the metal absorbs up to 40 at. pct of oxygen without forming a new phase. The solubility of nitrogen in the lattice has been studied by de Boer and Fast4 and Fast10 and is found to be considerable. At higher temperatures the oxide dissolves in the lattice at an appreciable rate according to Fast10 and the zirconium surface becomes active. De Boer and Fast4 and Hägg18 have studied the solubility of hydrogen and find that at room temperature the solubility corresponds to ZrH1.95 Desorption occurs on lowering the pressure. Hydrogen is stated to be more soluble in the ß-form and the

Jan 1, 1950

By C. Crussard, R. Tamhankar

It is the policy of The Metallurgical Society to provide, in the TRANSACTIONS OF THE METALLURGICAL SOCIETY OF AIME, a prompt and accurate medium for publication of reports of significant new research in both the scientific and engineering aspects of metallurgy. Papers submitted to the Society are judged by competent reviewers accord-ing to established criteria for technical merit, accuracy, originality, and presentation. STAFF: Editor, Gerhurd Derge Carnegie Institute of Technology Schenley Park Pittsburgh 13, Pa. Editorial Assistant, M. A. Redmerski Staff Coordinator, James J. Burke THE METALLURGICAL SOCIETY: W. R. Hibbard, Jr., President; J. C. Kinnear, Jr., Past-President; John Chiprnan, Vice President; T. D. Jones, Treasurer; R. W. Shearman, Secretary. PUBLICATIONS COMMITTEE OF THE METALLURGICAL SOCIETY: A. W. Thornton, Chairman; Dennis Carney, John Chip-man, J. C. Fulton, J. H. Hollomon, H. H. Kellogg, A. E. Lee, R. Maddin, J. D. Sullivan, and D. Swan. Review and selection of manuscripts is under the supervision of the following Publications Committees: Extractive Metallurgy Division: T. B. King, Chairman; S. J. Dickenson, R. P. Hermsdorf, R. Schuhmann, Jr., and P. T. Stroup. Institute of Metals Division: Robert Maddin, Chairman, F. Lincoln Vogel, Jr., Vice-chairman, W. A. Backofen, R. W. Balluffi, J. H. Bechtold, M. B. Bever, R. S. Busk, C. G. Goetzel, Paul Gordon, C. D. Graham, .Jr., Robert F. Hehemonn, R. I. Jaffee, F. E. Jaumot, Jr., Irving R. Kramer, A. J. Lena, Harold Margolin, C. J. McHorgue, Russell A. Meussner, J. B. Newkirk, H. W. Paxton, G. E. Pellissier, I. S. Servi, Alan U. Seybolt, A. J. Shaler, and Jack Washburn. Iron and Steel Division: J. C. Fulton, Chairman; T. B. King, F. C. Langenberg, W. 0. Philbrook, and T. 0. Winkler. Published bimonthly by the American Institute of Mining, Metallurgical, and Petroleum Engineers, Inc., 29 West 39th Street, New York 18, N. Y. Telephone: PEnnsylvania 6-9220. Subscription $20 per year for non-AIME members in United States and North, South, and Central America; $25, foreign; $5 for AIME members. Single copies, $4.00, single copies foreign, $5.00. The AIME is not responsible for any statement made or opinion expressed in its publications . . . Copyright 1958 by the American Institute of Mining, Metallurgical, and Petroleum Engineers, Inc. . . . Registered cable address, AIME New York ... Indexed in Engineering Index, Industrial Arts Index, and Chemical Abstracts... Second class postage paid at New Yark, N. Y., and Ann Arbor, Mich. Volume 212, Number 6.

Jan 1, 1959

By Clyde E. Williams

The purpose of this report is to supply the Coal Classification Committee&apos; with information for use in the formulation of a system of classification of coals according to their uses. Consideration is given here only to the nonferrous metallurgical operations that consume relatively large amounts of coal or coke; i. e., the smelting of copper, lead, zinc and aluminum. For all of these uses, coal of certain definite qualities is desired. Geographical location, however, often determines whether these qualities can be specified. In some instances the preferred qualities must be specified, regardless of cost. In others, quality may be sacrificed for lower cost, although the best quality consistent with cost is usually the determining factor. These considerations will be outlined in the following discussion under the various uses, which, however, will illustrate the impracticability of preparing definite specifications for coal used in the majority of the nonferrous industries. Coal and Coke in Copper Metallurgy From the standpoint of coal consumption, copper smelting and refining operations are the most important of the nonferrous metallurgical uses of coal. As nickel ores treated in the United States and Canada are associated with copper, the first step in their recovery is really a copper-smelting operation; accordingly, the following considerations under copper smelting apply equally to nickel. Copper Smelting in Reverberatory Furnaces.—For a long time, rever-beratory copper-smelting furnaces were fired with lump coal burned on grates in a fire box. Later, lump coal was displaced by pulverized coal or oil burned directly in the smelting chamber. Recently, natural gas has been used in several plants, although producer gas was used for this purpose at Great Falls as early as 1903.2 Requirements for coal used in

Jan 1, 1932

By G. Baralis, P. Gondi, I. Tangerini, G. Scandola

The precipitation behavior of Zn-0.5 pct A1 alloy single crystals was studied by means of electrical resistivity measurements and by optical and electron microscopy. The single crystals for the resistivity measurements were prepared by an original method in - 100-p -thick sheets. The order of the precipitation kinetics ranged between 1 and 1.5. The dislocations play a relevant role in the first-order kinetics. Precipitation always occurs both on dispersed particles and on dislocations. Statistical examinations have shown that the first-order kinetics can have two different activation energies; i.e., the precipitation can have dz;fferent mechanisnrs which could not be identified, however, in the course of the research. During the tnetallographic exanzination of the precipitation structures a specific process of dislocation decoration was obsereed. The main purpose of this work was to study the contribution of dislocations to the precipitation. A number of authors have observed precipitation on dislocations and reference might be made to several monographs on the ubject.&apos;&apos; The possibility that dislocations also accelerate precipitation has been considered by Turn-bull3 and Fischer et al.4 The studies described in the present paper were carried out on zinc, chosen as a base metal owing to the ease with which dislocations can be introduced into it and because of the absence of excess vacancies after quenching in conditions where phenomena of accelerated precipitation still occur. Aluminum was preferred as alloying element because of the accelerated precipitation phenomena that resulted in a preliminary reearch. EXPERIMENTAL METHODS The observations refer to a Zn-0.5 pct A1 alloy. The zinc was 99.995 pct pure; a typical spectroscopical analysis is given in Table I. As a rule the alloy was subjected to homogenization, quenching, or slow cooling and annealing. Homogenization was carried out by heating at 390" to 410°C for 24 hr. From the homogenization temperature, some specimens were quenched and some slowly cooled at a rate of 2°C per sec. At this rate no precipitate was detectable under the optical microscope just after cooling. Quenching was carried out simply by dropping the specimens into water, aqueous ethylene glycol solution at -30" c, or liquid-nitrogen baths placed close to the homogenization oven. Vaseline oil baths were used with a thermal stabilization of 10-20 for both the aging treatments and the measurements; aging was generally carried out at 90" or 130°C. To avoid oxidation phenomena during heating, the vaseline oil baths had to be frequently renewed. The precipitation kinetics were studied by means of electrical resistivity measurements, using ans potentiometric method (reproducibility ± 5 x 10 5 v, that is 0.5 pct of the total voltage decreases on the specimens during precipitation). First, various types of specimens were tested, i.e., polycrystals, single crystals grown in capillary quartz tubes, and thin single-crystal sheets prepared by means of an original method requiring no container except for the natural oxide. Even if fully annealed, the polycrystals and the capillary grown single crystals showed resistivity in -creases, most probably due to dislocations introduced in the course of the measurements. Similar resistivity increases in pure zinc were noticed by another author. Only the single-crystal sheets showed no resistivity change; thus they were chosen for the subsequent tests. As already mentioned, these single crystals were obtained by using, as a container, the natural oxide on the zinc surface; the oxide strength is sufficient to maintain the original shape during melting with sheets up to 500 p thick. An initial zone melting and subsequent zone leveling, which led also to formation of the single crystals, were thus carried out on rolled sheets of the required thicknesses (- 100 p) and shape, lying on a flat silica surface. The resistivities were first evaluated by measurements at the liquid-nitrogen temperature. This method gave poor reproducibility, however, and this was attributed to the thermal cycles which had to be operated. To avoid cycles and handling, it was therefore decided to make measurements directly in the annealing oil baths; this required thermal stabilization at ilo-&apos; "C. In this way only the resistance changes were measured. Specimens of pure zinc and of completely annealed alloy were always examined as controls together with those under consideration; only those measurement runs were taken into account where the reference samples showed no resistance increases. Again, the main inconvenience was due to oxidation and this was avoided by renewing the oil baths; even so data reproducibility was poor and the observations were therefore carried out on a large number (many hundreds) of specimens so as to provide indications of statistical value. For the transmission observations under the elec-

Jan 1, 1969

By Oscar Weiss

STILFONTEIN and surrounding areas gave negative results in all prospecting attempts since about 1904 when Goerz and Co., a forerunner of Union Corporation Ltd., first drilled in the region and on the farm Stilfontein. Subsequent efforts by African and European Investments Co. and Anglo American Corp. from 1934-37 were completely unsuccessful. Holes drilled by these companies on the farms Rietfontein, Hessie, and Palmietfontein were stopped in the Lower Witwatersrand system without finding payable reefs.

Jan 10, 1951

By Francis Laur

BAUXITE, at first considered as a mineralogical curiosity without importance, now attracts daily increased attention from mineralogists, geologists, and manufacturers. The metallurgy of aluminum, which has entered with the advent of electrolysis upon a new phase within the last few years, requires every day larger quantities of pure alumina, and this can only be obtained from bauxite, which is, of known substances, the richest in free alumina. Bauxite has been mined since 1872 in France, whereabout 200,000 tons have been produced, and where, as a natural consequence, its deposits, qualities, and applications have become known. Within a few years past, discoveries of important deposits of bauxite have been made in the United States and Canada, and this almost entirely new subject has thus acquired an additional interest for the mining engineers and metallurgists of the American continent. A brief summary of the available data concerning it appears likely, therefore, to be appropriate and valuable.* I.—HISTORICAL. It was in 1821 that the famous chemist Berthier discovered at Baux (Bouches du Rhône) a hydrate of alumina (varying from 66 to 79 per cent. in its contents of the oxide) mixed with silica and

Jan 1, 1895

Allan Gibb, Queensland, Australia (communication to the Secretary*):—It is gratifying that Mr. Edward Keller,&apos; who has clone so much work elucidating the principles of copper-metnllurgy, should have subjected only that portion of our investigation relating to magnetic iron oxide to anything like adverse criticism. Situated as we were on a rnining-camp, it was impossible to undertake work that would cover all the intricate possibilities connected with the materials commonly classed as matte. We therefore began the investigation on matte produced from ores that contained no other components than the sulphides of copper and iron that would be likely to enter into the composition of matte. We were, accordingly, free from ally possibility of magnetic iron oxide entering the matte, unless it were formed in the operation itself. The work done on this subject was incomplete, and the results thereof recorded as giving only negative evidence as to the absence of magnetic iron oxide. It would have been better to have left the matter open, as " not proven." The trend of the investigation was to account for the insufficiency of sulphur in matte to satisfy the requirements of ferrous and cuprous sulphides. So far as our deductions are correct, it was unnecessary to consider the (in our samples) somewhat doubtful constituent, magnetic iron oxide. The mattes that mere investigated were among those mentioned by Mr. Keller, " which scarcely show ally magnetic property." The samples showed no such property. There was no unaccountable variation in the specific gravity, which only varied, as would be expected, with the proportion of ferrous sulphide. I have had experience in smelting ores of which the gangue was a siliceous magnetite, both in blast- and rever-beratory furuace. The mattes so produced contained magnetic

Jan 1, 1908

By R. A. Falconer, H. L. Lovell

With increasing requirements for fine coal cleaning and the many advantages of the cyclone operating on a coal-water slurry, a series of studies designed to achieve an enhanced understanding of the cyclone parameters has been pursued. The purpose of this investigation has been to vary a series of dimensional parameters with an experimental 15-in. diam hydro-cyclone, and to determine the relative effects of parameter variations upon ash and sulfur removal. This study of the hydrocyclone is a continuation of a series of investigations, conducted in the Dept. of Mineral preparation at The Pennsylvania State University, which are directed toward the removal of ash and sulfur constituents from fine bituminous coal by size-density separations in cyclones, and toward a fuller understanding of the complex mechanisms involved in such separations. The purpose of this investigation has been to vary a series of dimensional parameters with an experimental 15-in. diam hydrocyclone, and to determine the relative effects of parameter variations upon ash and sulfur removal. Of special interest was the response to cone angle variation, since it is the high included cone angle that generally distinguishes the hydrocyclone as a gravity separator rather than a classifier. DESCRIPTION OF THE HYDROCYCLONE Fig. 1 is a dimensional drawing of the hydrocyclone used in the investigation. The unit was designed and fabricated by Heyl and Patterson, Inc., for experimental use. The dimensional parameters considered were: 1) Three cone sections having included angles of 45, 60, and 95,degrees, 2) Three 3 1/8 in. diam vortex finders having lengths of 15, 17, and 19 1/2 in., 3) Three 4 1/16 in. diam vortex finders having lengths of 15, 17, and 19 1/2 in. 4) Two apex sections having diameters of 2 and 2 1/4 in. The feed inlet orifice had a fixed diameter of 3 in. The hydrocyclone test installation was made at The Pennsylvania State University pilot plant at Barnes-boro, Pa., which operated at 50 tph. During the period that the hydrocyclone was tested, research was in progress at the Barnesboro site to reprocess refuse material from a near-by coal preparation plant in

Jan 1, 1968

By Carl Pierce

The writer of this article has not attempted to write a technical paper; on the contrary, he has tried to express in "steel-plant English," for steel men, a viewpoint drawn from his practice and experience. It is not his thought that it shall be taken as the "last word" in the making of this class of steel, or that good rimming steel cannot be made by any other practice. The paper was written to serve as the basis of a discussion from which it is hoped much benefit may be derived. The paper deals only with rimming steel made by the open-hearth process, and with the lower carbon steels, such as sheet and tin bar, rivet stock, skelp, etc., although good rimming steel as high as 40 to 50 carbon can be made by having good open slags and giving proper attention to working and tapping temperatures. Definition of Rimmed Steel Rimmed steel is sometimes called open or effervescing steel to differentiate it from killed or partly killed steel. It is steel made by a process which permits the free escape of gases from the metal in the molds. In passing up through the metal, the gases keep it in a rolling action from the walls of the mold inward. The top of the ingot rims in as the metal chills and the walls of the ingot get thicker, the center part remaining fluid until it reaches a pasty condition when it is covered with a cast-iron cap. The Charge In making up a charge for rimming steel, clean stock of a known composition must be selected, special attention being given to the analysis of the materials. The silicon in good rimming steel must be eliminated to a trace, therefore it is advisable to have a uniform amount going into the charge. Too much silicon gives a raw melting heat from which rimming steel is unlikely to result. For this reason a charge containing not to exceed 40 per cent. pig iron and 60 per cent. scrap, with no iron ore, is preferred to the Monell type of charge in which as high as 65 to 70 per cent. pig iron is used with a proportional amount of iron ore for the removal of the excess silicon and carbon. The silicon content of pig iron varies so much from day to day in the average blast-furnace practice that there is danger of getting too much of this element in the latter mixture when

Jan 1, 1926

By R. W. Raymond

In a former paper (Trans., xvi., 770) I gave the text of the archaic mining law of the State of New York, together with some comments upon its curious provisions. In that connection I pointed out two facts : first, that the law seemed to have originated in the schemes of private parties, who were satisfied with those parts of it which concerned them particularly; and secondly, that the remaining provisions had been hitherto quite inoperative, for the reason that mines of the character to which they referred had not been discovered in the State. Since 1888, when that paper was written, the New York Legislature has passed several acts relating to mines as follows: 1. Chapter 394, Laws of 1890. This provides for an inspection

Jan 1, 1895

By Clifton W. Livingston

So many factors influence blasting results that theories and rules are usually dismissed as impractical; the practice prevailing today is arrived at by cut and try. Usually the first step is to experiment with drillhole patterns and spacing until an arrangement is found that gives best results. The next step is to experiment with different types of explosives and sequences of blasting until the most satisfactory degree of fragmentation is achieved and until no further reduction in cost is immediately apparent. Improved fragmentation is generally attributed to the type of powder used, the sequence in which the holes are blasted, or the use of millisecond delays. Various types of drill rounds have been evolved in tunneling operations, underground development headings, and stoping, and various patterns of blasting in open pit mines and quarries. These practices usually are carried from mine to mine or from district to district, and great skill is exercised by those experienced in the art of blasting.

Jan 1, 1960

By J. E. Ryan

TRONA, Calif., is a miniature urban community of some 3500 people, located on the northwest shore of dry Searles Lake in the extreme northwest corner of San Bernardino County, approximately 186 miles north and east of Los Angeles. Since it is situated on the Mojave Desert, a typically desert climate prevails with wide variations in temperature between day and night, extreme daytime summer heat, and cool to cold winters. Rainfall averages somewhat less than 4 in. per year, and dust storms are common. The rate of evaporation, .however, is great, amounting to 6 to 9 ft of water per year. The extremely low humidity makes the summer heat of 110°F tolerable with only a mild, temporary discomfort. Nature of Deposit During the periods when Searles Basin was flooded, the waters that passed through Indian Wells Valley spread out to form a broad, shallow lake providing, in effect, a settling basin for suspended sediment. The drainage into the deeper and more isolated Searles Basin thus was clarified to a great degree before concentration began. Today, the elevation of the dry surface of Searles Lake is 1618 ft, and the salt deposit measures 5x7 miles. At the eastern and northeastern margins of the main playa zone and just at the foot of the alluvial slope of sand and coarser wash from the Slate Range mountains, a rim of crusted salts rises a few feet above the level of the flat. The deposit is a saline efflorescence composed of salts that were presumably brought up with rising ground waters to be deposited at the surface by solar evaporation. This deposit consists chiefly of trona, and it is after this Trona Reef that the town Trona was named. Strip mining operations have been conducted in the past at infrequent intervals for the recovery of crude trona salts. The main focal point of interest in Searles Lake from a commercial standpoint is the main salt body located almost centrally in the basin. The exposed portion of this porous saline deposit covers approximately 12 sq miles and averages 71 ft deep. Its interstitial voids, which constitute 50 pct of the total volume, are permeated with a brine, which is in equilibrium with the soluble salt deposits. The brine is the raw material for the operations of the American Potash and Chemical Corp. plant at Trona, shown in Fig. 1. The soluble salt deposits are of interest for their potential values in future technologic development. The brine, which is stratified according to slight differences in density, stands usually within 6 in. of the surface of this exposed, firm, salt body. The surface is usually dry and will support the weight of heavy mobile units and drilling equipment. Occasionally, however, surface waters from the higher watersheds encroach upon the main salt body during infrequent periods of precipitation on the surrounding mountains. This water dissolves surface salt, becomes a dilute brine, and has been observed to stand as high as 18 in. above the salt surface when undisturbed. Windstorms will shift the water back and forth across the lake surface. The exposed salt body is surrounded by additional submerged areas of commercial soluble salt deposits covering some 20 sq miles, hidden from view by marginal playa mud. These vary in depth up to as much as 30 ft. Thus, the outline of exposed and submerged salt deposits of commercial value is estimated to cover a total area of 32 sq miles, which is roughly circular but slightly elongated from northwest to southeast. It has been estimated that each square mile contains about 100 million tons% f alkali salts. The results of drill borings in the past 15 years have brought to light the interesting fact that the main salt body lies superimposed on an impervious mud deposit from 10 to 15 ft thick containing relatively little soluble salt. Under this deposit lies a second soluble salt body 35 ft deep. The lower salt body is interspersed with numerous insoluble mud lenses and its composition is considerably different from that of the primary, or main salt deposit. Recent drill borings have not penetrated beyond 300 ft. They have, however, revealed that underlying the lower salt body, the mud sediments carry deposited minerals of trona, nahcolite, mirabilite and much less soluble carbonates or sulphates of calcium and/ or magnesium. This structure is shown in Fig. 2. Current Lake Survey Program Several hundred holes have been drilled in the deposit. However, to carry out a thorough and carefully correlated study of the composition of the soluble salts and other minerals in the dry lake basin, a drilling program was inaugurated recently and is now nearing completion. In this survey, pattern drill holes are sunk at regular lh-mile intervals to a depth of approximately 150 ft. Drilling equipment consists of a No. 51 C. P.

Jan 1, 1952

By Charles F. Johnson

A pulse technique is described for the measurement of bar velocity. A low frequency sine wave pulse is used which allows the wave-length to become much larger than the lateral dimensions of the test specimen. The low frequency pulse method has been tested and compared with the resonant frequency method and the results show that both methods give, on the average, equivalent velocities.

Jan 1, 1971

By Gerald Sherman

IN the southern field of the anthracite region of Pennsylvania, many of the coal seams dip at angles of 40° to 50° from the horizontal. For transportation purposes, "tunnels" are driven across the coal measures and, occasionally, "rock gangways," beside the seams and parallel with them. The use of gangways driven in country rock appears to be increas-ing, as they avoid the maintenance&apos; of long gangways in coal, which eventually are driven to the colliery boundaries, and permit mining from a number of intermediate blocks without interference. The rock consists of slates or sandstones of moderate hardness, which may range into very hard, highly siliceous, fine-grained conglomerates. In this distinctly bedded formation,&apos; the direction of the heading, whether parallel with or across the structure, makes it necessary to distribute the drill holes in a different pattern to break the ground, but does not change loading conditions. In 1932, practically all the mucking was done by hand, and it was the established custom to use four men on two drills for drilling and breaking the ground, and five for loading it, out. A driver and mule was needed in addition, to assemble the rock cars at a siding or branching track in the rear, pending their final disposal. This might occupy the driver&apos;s whole time, or if the length of haul were short, he might be able to do other useful work. It was thought possible in 1932 to reduce the cost of driving such headings in rock by mechanical loading, and to investigate this subject a scraper loader was used in a section of tunnel then being driven. Opera-tions while driving 195 ft. of this tunnel using a scraper loader were care-fully observed. Time studies were made of the loading, and records made of the routine of breaking ground, but not in such detail. Tunnels or gangways in the colliery are 7 ft. high above the rails, by 10 ft. wide, which requires a minimum of 8 ft. in height, broken to allow for rails and ties. This cross section is of sufficient size to permit the use of any one of several types of power loaders, but for this demonstration if was found most convenient to use a scraper loader.

Jan 1, 1936