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By Clarence Wright

THE average lead and zinc content of the ores mined and milled in the Joplin district is low as compared with that of other lead and zinc deposits throughout the United States. Because of this fact and of the high grade of the concentrates, the ratio of concentration is unusually high. Most of the operating companies have aimed to produce as high a grade of concentrate as possible in order to obtain the highest price for their product. They have done this at the sacrifice of the percentage of zinc recovered. The average percentage of zinc recovery is from 60 to 70 per cent. For percentage of recoveries from actual mill tests, see tables. The concentration is commonly effected by crushing the ore to h-in. (12.7 mm.) size and subjecting it to a roughing and cleaning over two or more large Cooley jigs, of the Harz type, the finer sands being treated on the usual types of sand and slime tables. The treatment of slimes by flotation is being tested at several of the larger mills. COARSE CONCENTRATION When the ore. has been hoisted from the mine it is dumped onto a chute leading to a grizzly made of iron bars, usually heavy rails, spaced 4 to -5 in. (101 to 127 mm.) apart. The oversize is caught on the grizzly, the mineralized pieces are broken with sledge hammers so as to pass through, and the boulders that are practically barren are sorted out by hand and trammed to the waste-rock pile. The proportion of waste rock thus sorted out varies from a fraction of 1 per cent to 15 per cent., depending on the nature of the rock.

Jan 10, 1917

By W. W. Lowry, G. C. Eggleston, W. E. Keck

THE potential iron ores of Michigan can be classified from the stand- point of the predominant impurities into siliceous, sulphurous and phosphorous ores. Research on the flotation of each of these classes of ore was carried out in the following manner. The flotative properties of the valuable minerals of iron and of the worthless and deleterious ones were first determined under carefully controlled conditions. This information was then applied to synthetic mixtures of these minerals, which simulated the potential ores. Finally, data obtained during the two foregoing stages of the investigation were used in the flotation beneficiation of samples of the potential ores. Hematite is the most important mineral of iron in each of the above classes of iron ores. This paper deals with a study of that mineral in the very nearly pure state. There are two varieties of the mineral-specular hematite and massive hematite. The latter is the principal variety, but the former is an important mineral of iron in some of the potential ores. Because of this condition, flotation research was performed with both varieties. This research consisted essentially of: (1) a survey of the literature on hematite flotation, (2) the preparation of pure massive hematite, (3) the preparation of pure specular hematite, (4) the development of a laboratory procedure and (5) flotation experimentation. For the purpose of this discussion, the results of previous work on the flotative properties of hematite can be summarized as follows: Specular hematite has been readily floated with terpineol and sodium oleate or heptylic acid1. Further, hematite has been likewise floated with a proprietary frother and oleic acid or other soluble oils2. Finally, lead nitrate, copper sulphate, silver nitrate, chromium nitrate, mercuric chloride, ferric

Jan 1, 1937

By N. F. Fiore, M. F. McGuire

THIS communication describes a series of experiments in which dislocation etch pitting was used to ascertain the depth of damage in crystals which were mechanically polished or which were cut with either a commercial metallographic cut-off wheel,* a com- All specimens were cut from single crystals of American Smelting and Refining Co. 99.999+ pct pure copper which were grown from the melt by the Bridge-man technique. The test specimens were disks, with faces being (111) planes and the disk axis a (111) direction. The disks were annealed in a vacuum of 10-5 Torr for 24 hr at 950°C prior to cutting or polishing and were given a light electropolishing in an ortho-phosphoric acid bath before etch pitting. Both Youngs1 and Livingston's2 reagents were used for etch pitting and the reagents gave identical quantitative results; however Livingston's reagent produced less staining and so all photomicrographs shown are of {111) surfaces etched with this solution. The surface of the annealed crystals showed well-defined subboundaries and a density of dislocations of about 1 X 106 per sq cm excluding those present in subboundaries, Fig. 1. The depth of cold work produced during mechanical polishing was determined after an annealed specimen was mounted in a paraffin holding block to protect it from extraneous damage. The exposed (111) surface was ground on metallographic papers and then polished on billiard cloth through 0.05-p alumina abrasive. It was necessary to remove about 0.3 mm (-0.01 in.) to obtain a structure representative of the annealed sur- face, indicating that the crystal was damaged to this depth during mechanical polishing. The cold work caused by standard cutting methods was measured in another series of tests in which cuts

Jan 1, 1967

By Joseph L. Gillson

BRAZIL has had an industry based on ocean beach deposits of heavy minerals containing monazite, zircon, rutile, and ilmenite for well over 40 years, but except at the very earliest period, prior to 1906, and again during World War 11, has this industry been at all comparable in size with similar operations in other countries. Limiting factors have been neither a lack of reserves nor lack of markets (except for zircon). Although poor local transportation and shipping facilities have handicapped the development in Brazil, these conditions were perhaps equally bad (when mining operations started) in the Indian State of Travancore, and in New South Wales and Queensland, Australia, in which states the principal production of beach deposits of heavy minerals has occurred. The outstanding restraints on the Brazilian industry have been the lower quality of the Brazilian minerals, the relative small size of individual deposits that were known until recently, the lack of interest of Brazilian investors in mining ventures, and the unfavorable climate for investment of foreign capital under Brazilian mining law. The lower quality of the minerals is indicated by the fact that the Brazilian monazite carries only 5 to 6 pct ThO2,*, and the ilmenite 56 1/2 pct TiO2, whiteness of the Australian zircon. An inadequate market for the abundant zircon that will be avail- able in any operation in Brazil is certainly a heavy restraint, since otherwise it could be an important byproduct. The oxide of zirconia, baddeleyite, that has come from Brazil is from other sources. 1 Since the Brazilian beach sands carry only a little rutile, that mineral has not been available as a valuable byproduct to help finance the operations.

Jan 6, 1950

By John T. Popp, Jodi A. Rulli, Anthony T. Iannacchione

Anomalous geological features in the coal and surrounding strata of a mine in northern West Virginia have fractured and deformed an inherently weak roof rock prior to mining. Horizontal stresses, as much as six times greater than overburden related horizontal stresses, have induced cutter roof failure. This failure was distinguishable from rock deformation associated with geological anomalies because it was induced by mining. The characterization of these features has allowed for the prediction of zones of unstable roof rock and the determination of failure trends on gateroad stability. Geological anomalies included clastic dikes and a narrow zone of sandstone roof. Clastic dikes, representing intrusions of shale and claystone, were invariably accompanied by local roof rock instability, and often formed the boundaries of roof falls. Shale was the dominant roof lithology except where a small sandstone occurred in the northwest portion of the longwall mining area. The sandstone occurs in two phases: a sandstone-filled channel, 5-m- thick and 60-m-wide, which eroded and replaced the shale roof and the upper part of the coalbed; and a sheet sandstone unit which was crossbedded to interbedded with the underlying shale. Horizontal stresses are naturally relieved through the initiation of cutter roof failure. This failure may extend from a few meters to several tens of meters horizontally, and from a few centimeters to several meters vertically. Orientations of entries and crosscuts has a greater influence on the direction and total length of cutter roof failure at the rib-roof intersection than does the principal directions of the in situ horizontal stresses. Seventy-four percent of the cutter roof failures occurred along the rib-roof intersection. Orientations of cutter roof failure away from the rib- roof intersection were clustered in the north-south direction and may have been influenced by the horizontal stress field.

Jan 1, 1984

By William L. Fink, Dana W. Smith

Many investigators have attempted to determine the true nature of the internal changes taking place during aging. Merica, Waltenberg and Scottlt were the first to propose a theory of age-hardening. They attributed the age-hardening of duralumin to the precipitation of minute particles of the compound CuA12. Later Zay Jeffries and R. S. Archer2 augmented the above theory by suggesting that the small CuAl2 particles acted as "keys" causing "slip interference." Many other investigators3 have devoted much time to the mechanism of age-hardening, some corroborating the "precipitation" and "slip interference" theory, others coming to different conclusions because of effects that to them seemed unexplainable by the early theories; e.g., the increase of electrical resistance upon aging, the fact that no change in lattice parameter could be detected during the early stages of aging even at elevated temperatures, and the fact that the density did not change as would be predicted. In 1932, Merica revised4 his earlier precipitation theory to take care of these presumably anomalous effects. This revised theory, the "knot" theory, assumes that substantial age-hardening occurs before actual precipitation of solute as discrete particles. The assumed mechanism is one of diffusion of solute atoms into groups forming distorted regions which act as "hard" spots and cause slip interference. These "knots" are assumed to have approximately the same lattice arrangement as the solvent. The anomalous behavior of lattice parameter, density, and electrical conductivity, require a modification of the simple precipitation-hardening theory, only if it is assumed that the precipitation of minute particles during aging has the same effects on these properties as the formation of large particles under equilibrium conditions. Data obtained by the authors in the study of the aluminum-magnesium system5 indicated that

Jan 1, 1936

By R. R. Sayers

Ventilation may be defined as the process by which vitiated air of an enclosed or partly enclosed space is continuously replaced by fresh air. Fresh air has been defined as invigorating pure air. Pure dry air at sea level contains the following gases:1 Analysis of Air at Sea Level Per Cent. Oxygen.................................................. 20.94 Nitrogen................................................. 78.09 Carbon dioxide........................................... 0.03 Argon................................................... 0.94 Helium, krypton, neon, xenon, hydrogen, hydrogen peroxide, ammonia, ozone........................................ traces Carbon Dioxide Limit For many years carbon dioxide was used as an index of the purity of the air vitiated by the metabolism of people. It was, however, well known that the untoward effects produced on those exposed to such air was not due to the concentration of the carbon dioxide. It has been found that the untoward effects on the comfort and efficiency of those so exposed are due to the increased temperature and humidity. It has been found that men can breathe air containing many times the amount of carbon dioxide found in our worst ventilated theaters and assembly halls, which, according to Rosenau, do not contain above 0.5 per cent, carbon dioxide. Nevertheless, in mines it sometimes occurs in sufficient quantities to cause symptoms in men or even unconsciousness and death. One-half of 1 per cent. of carbon dioxide in normal air causes a slight and unnotice-able increase in the ventilation of the lungs, that is, a man exposed to one-ha,lf of 1 per cent. of carbon dioxide will breathe a little deeper and a little faster than when in pure air. If 2 per cent. of carbon dioxide is in the air, the lung ventilation will be increased about 50 per cent.; if there

Jan 1, 1927

OPEN-HEARTH refractories are not merely an accessory to the furnace. They themselves ore the furnace, to all intents and purposes. The steel work of the main structure is merely a frame which helps to support the refractories; and the regenerators, a necessary part of the furnace system, consist almost entirely of refractories with very little supporting structure. Not only do refractories constitute the essential part of the furnace, but they also carry the liquid steel all the way to the point where it begins to solidify. On leaving the furnace the liquid passes through a refractory runner into a refractory-lined ladle, then through a refractory nozzle closed by a refractory stopper on the end of a refractory- protected rod. The liquid is sometimes sent through an additional refractory-lined tun-dish, a supplementary ladle, or a refractory runner for bottom pouring, until it finally enters the iron mold in which it solidifies. Even in the mold, refractory materials are sometimes used to provide a non-conducting "hot top." These materials, from ladle to hot top inclusive, are often referred to as the "pouring-pit refractories." CAUSES OF FAILURE Compared with the equipment used in most industrial processes the open-hearth furnace has a relatively short life. The most important quality of an open-hearth refractory, therefore, is its rate of failure. The discussion here of the individual refractory materials will therefore keep uppermost the question "Why, how, and where does it fail?" The principal causes of failure of open-hearth refractories are, in their order of importance: 1. Reaction with iron oxides. 2. Reaction with slag. 3. Flow and failure under load. 4. Melting. 5. Spallimg. 6. Mechanical breakage. Reaction with Iron Oxides and Slag. This is by far the most important cause of failure. Liquid iron oxide comes very near to being the

Jan 1, 1944

By David Cole

AT the time flotation appeared upon the metallurgical horizon in Arizona, the writer, under the direction of Dr. Ricketts, was engaged in remodeling and enlarging the No. 6 Concentration Plant of the Arizona Copper Co. at Morenci, and the work had been in progress nearly a year before the Inspiration experiments with flotation had disclosed the revolution in concentration that was at that timè impending. The simplified flowsheet worked out for the remodeling of the Morenci plant had been based upon the removal of the freed metal in a minimum number of stages by treatment upon tables equipped with Butchart riffles, the latter being adapted to accomplish both classification of feed and removal of the metal at one operation, substantially as described in my previous paper.1 The scheme of treatment for the slime was based upon the well-known fact that after copper sulphides, such as chalcocite and chalcopyrite, etc., are reduced to a certain extremely fine state of comminution they are definitely beyond the reach of separation upon any of the concentrating devices then known. By using drag-belt classifiers (which served as conveyors as well as separators), the overflow would be of the usual "slimes" class. Experiment had shown that when these drag-belt overflows were, properly diluted (that is, to about 5 to 7 per cent. solids in the feed under treatment) . the very fine sand, and especially the very fine but still granular sulphide particle's, would, if given a short distance to fall, quickly settle out in prime condition to yield an excellent recovery on vanners; a further valuable feature would be that the very fine non-separable final overflow tonnage might be discharged direct to tailing, thus conserving space requirements so as to permit within the old building, without embarrass-ment, the increase of capacity required.

Jan 9, 1916

By Charles Barrett

PLASTIC flow in metal crystals and the changes in orientation resulting from it are generally understood to take place by the following funda-mental mechanisms: (1) slip on crystallographic planes, (2) homogeneous crystal rotation resulting from the slip, (3) bending of the lattice between the planes of slip, and, under certain circumstances, (4) twinning. This paper and a preceding one on iron subjected to uniaxial compression1 concern two additional processes that must now be added to this list: (5) the formation of deformation bands, and (6) the bending and rotation of these bands. The present investigation yields a new understanding and definiteness to the common terms so loosely used when speaking of cold-worked metals -"grain fragmentation," "elongated grains," and "deformation twins," "deformation bands," "etch bands," or "X-bands." Bands have been noted on the polished and etched surfaces of cold-worked metals by vari-ous investigators for more than 25 years, ? yet their nature and their significance have been so little understood that they are not treated in the most comprehensive modern texts on the deformation of crystals. The experiments in this series show that they are one of the fundamental processes in the deformation of metals, of importance in the development of preferred orientations, in work-hardening (since they have the effect of reducing the effective grain size and interfering with slip), and in the recrystallization process. The present experiments were performed on the same stock of mate-rial that was used in the earlier compression experiments1-hydrogen-purified mild steel in which the carbon content had been reduced to the limit detectable under the microscope and in which single crystals could be grown by a strain-anneal treatment.2

Jan 1, 1939

By J. J. Mulligan, F. F. Colcord, E. F. Kern

The electrolytic separation of silver and gold has been practiced by the refineries in the United States for a good many years, and probably because of frequent visiting between officials of plants and the consequent exchange of views, operations in the various silver and gold refineries are very similar. We find, for instance, they practically all use electrolytes of approximately the same composition, which, no doubt, is more the result of experience than of studies of electrolytes. At the new electrolytic parting plant of the U. S. S. Lead Refinery, Inc., East Chicago, Ind., considerable attention has been given to the composition of electrolytes, especially to their conductivity and their effect on the character of the silver deposit. We are not aware that anything has been recently published on this subject and are, therefore, presenting such data as we have with the idea that, although it will not be wholly new, it may stimulate interest in the subject. Effect of Copper Content on Conductivity The first work was to determine the specific conductivity of silver nitrate and copper nitrate solutions. Concentrated solutions of silver nitrate and copper nitrate were prepared by dissolving analyzed chemically-pure salts in distilled water, and determining the silver and copper in each. Definite amounts of the concentrated solutions were taken, mixed and diluted to a definite volume. The silver and the copper were determined in each of these solutions and the conductivity was then determined. The plotted results are shown in Figs. 1 and 2. The effect of increasing quantities of silver and copper is readily seen. A comparison of the two sets of curves shows conclusively the benefit of holding the copper content of the electrolyte above 5C g. per liter, as its effect is to increase greatly the conductivity in an approximate propor-

Jan 1, 1926

By Edwin Ludlow

For many years, coal has been known to exist in the valley of the Sabinas river, in the State of Coahuila, and for about 15 years it has been worked by the Mexican International Railway Co., which opened mines for its own fuel-supply when the railway was built, and has been mining continuously ever since. The coal-basin worked by this company lies along the Sabinas river, principally on the SW. side. It covers a wide area and has been carefully prospected, but only in a few parts have the beds been found sufficiently thick and regular for economical operation. This Sabinas basin was considered the only one in this field, until, in the Spring of 1899, the Las Esperanzas basin was found by Messrs. J. L. Elliot and E. D. Peters, who were in Mexico looking after some copper-properties. After a further examination by Mr. James T. Gardiner, of New York, the Mexican Coal & Coke Co. was organized in June, and active work was begun on Nov. 5, 1899. The coal-field of Las Esperanzas, situated in the State of Coahuila, about 85 miles SW. of Eagle Pass, Texas, adjoins and runs parallel with the Sabinas basin—an anticlinal separating the two outcrops by about 2 miles. Fig. 1 is a sketch-map of a part of the basin. The coal-formation is in the Upper Cretaceous, and corresponds with the Laramie measures of the United States. The following geological section, taken in Nogales canon, shows the measures between the massive limestones forming the Sierra de la Santa Rosa and the outcrop of the coal: Section. Feet. Limestone,...Unknown. Blue shale,.........110 Shale and sandstone,.. 60 Bed of fossiliferous shale,. 60

Jan 1, 1902

These pages may be used as order sheets. Mark the number desired opposite title of pamphlet wanted, add your name and address, tear out the sheets and mail them to us. Single orders 25 c. Pamphlets 10 c. each in lots of three or more. Pamphlets 5 c. each in lots of fifty or more. These prices prevail for orders for pamphlets of the same or different titles, when cash accompanies order. The pamphlets listed on the following sheets are advance copies printed to facilitate discussion at the meetings of the Institute. They are offered for sale at the reduced prices given above as long as the supply lasts. This list is published in the Bulletin in order that members may have the first opportunity to secure pamphlets, which sometimes are in such great demand that the supply is exhausted before the wants of members can be supplied. The following list includes only a fraction of the pamphlets that have been published by the Institute. Any other paper published by the Institute may be obtained for the price of $1, except those published in Volume XXXI, which are rare. The Institute is still selling back volumes of Transactions at reduced prices, but some of these volumes are becoming rare and members who desire to complete their sets of these very important books on mining and metallurgy are advised to send in their orders as soon as convenient. The attention of members is also called to the bibliographical index of the science of ore deposits contained in the Emmons Volume which is selling at $3 in paper and $4 in half morocco. The Posepny Volume is already exhausted and members who do not get in their orders for the Emmons Volume at the present reduced price may soon find themselves unable to obtain it on such favorable terms.

Jan 8, 1917

By C. A. Mitke

(Butte Meeting, August, 1913.) 1. Character of Gases which Caused Helmets to Get Out of Order. DURING September, -1911, the fire area in the Lowell mine continually increased and gases resulting from the fire came through the upcast shaft. These gases contained such a large percentage of sulphur dioxide that the men were unable to go up and down on cages, and, within a comparatively short time, repairs in the shaft were found to be necessary. Since the fire was in sulphide ores and extended into certain timbered sections, the gases contained varying amounts of SO2 CO2, and perhaps, at times, CO. The temperature in the shaft was generally about 97°, and the relative humidity from 97 to 99.5 per cent. The corrosive action of the fumes became apparent when the cables had to be changed more often than usual, the heads of lag screws .in the guides of the shaft disappeared, and the cages needed frequent repairs. It also became necessary to repair two compartments of the shaft by putting in 150 ft. of new guides between the 600 and 800 levels and lag screws in nearly all the old guides from the surface to the 800 level. 2. Ordinary Methods of Testing Helmets which were Unsatisfactory. These conditions required all work to be done by men wearing oxygen helmets. The Draeger type was tried, and was used until all repairs were completed. At first the helmets were. tested for air circulation and air tightness and the injector was tested by water gauge according to the methods recommended by the Draeger Oxygen Apparatus Co. Six arrangements, covering .these different tests, are illustrated in the catalogue and circulars of the company.

Jan 7, 1913

By José Geraldo Vieira

Companhia Vale do Rio Doce (CVRD), founded in 1942, is located near the town of Itabira, Brazil. Its iron ore deposits include over 500 million metric tons (mt) of high-grade hematite and about 2 billion mt of itabirite (banded rock formed by thin alternate layers of hematite and silica). These deposits are part of the Iron Ore Quadrangle, of which the overall reserves have been estimated at more than 30 billion mt. The magnitude of the project meant difficult early years for the company, including large investments, extensive railroad rehabilitation, and construction of ore port and ore handling facilities. Companhia Vale do Rio Doce was organized as a stock company, and 91% of its shares are presently owned by the Brazilian government. Financing has been accomplished in part through loans from international monetary agencies foreign banks, and foreign industry, as well as Brazilian banks. The company markets mainly abroad. In 1967, it exported 10.6 long tons (It) of ore, principally to West Germany, Japan, Netherlands, Italy, France, United Kingdom, and the United States. The Rio Doce geographic region where CVRD operates is strategically located among the large population centers of Rio de Janeiro, Belo Horizonte, Salvador, and Vitoria (Fig. 1). It covers an area of approximately 81,000 sq km in the states of Minas Gerais and Espirito Santo, and its population in 1968 was about 3.5 million. This region presents excellent prospects for development, with factors favorable for forestry, agriculture, grazing, and exploration for minerals other than iron ore, Electric power (hydroelectric plants) is available, as well as two main systems of transportation: the Rio-Bahia highway and the Vitoria-Minas Railroad. Pioneer activities at Itabira started about 1720 as small gold mining centers. The town is about 80 km northwest of Belo Horizonte and

Jan 1, 1969

By W. E. Keck, Paul Jasberg

THERE is a considerable tonnage of iron ore in the Menominee Range of Michigan that is unsalable only because it has too large a content of sulphur. Beneficiation of such ore is economically desirable, as a relatively large quantity of finished concentrate would be obtained (deleterious sulphur mineral content being generally less than 5 per cent) and because large blocks of such ore have been developed incidentally during search for low-sulphur ore. Research on the flotation beiieficiation of these high-sulphur ores consisted of: (1) a study of the flotative properties of the principal minerals in a nearly pure state, (2) flotation of synthetic mixtures of these pure minerals and (3) application of this experimental information to samples of the ores. Gypsum in iron ores is extremely deleterious; but when sufficiently free from impurities it is a valuable commodity. In 1934, the United States produced 1,500,000 tons of calcined and uncalcined gypsum valued at $13,700,0001. Of this quantity and value, Michigan produced approximately 19 per cent4. Thus this investigation may also prove to be of interest in connection with the gypsum industry if minerals separation, such as flotation, becomes necessary in the future processing of gypsum. Data on the flotative properties of gypsum would also be of interest to the science of flotation because such information has been extremely limited. The technical literature reveals one reference to the flotation of gypsum, in which was discussed the use of the mineral, with several others, to determine the relation between the floatability of minerals and the pH of the flotation solution2. This investigation necessarily was not comprehensive in regard to gypsum, but it did show that the mineral could be floated with oleic acid under varying pH conditions.

Jan 1, 1937

By E. Posnjak

IT is rather the general belief that acidified solutions of ferrous salts are readily oxidized when in contact with air, and often elaborate pre-cautions are taken to prevent it. This, however, is not the case and several statements may be found in the literature expressing surprise at the extreme slowness with which oxidation takes place when air or oxygen is bubbled through such a solution. Thus C. Baskerville and R. Stevenson1 "observed with surprise" that no. oxidation apparently took place, as shown by titration with 0.5 N KMnO4, when a stream of air was passed for 3 hr. through an acidified solution of ferrous ammonium sulfate or ferrous sulfate. The same authors state that even the presence of salts such as cobalt, chromium, copper, manganese, etc., which usually act as oxygen carriers, had "no effect upon the oxidation as was observed by, passing air for 3 hr. through solutions of Mohr's salt acidified with sulfuric acid." While this statement will be proved further on to be at least partly incorrect the slowness of the oxidation of ferrous salts alone has been previously established by McBain.2. His investigation also showed that the rate of oxidation increases markedly with an increase in the concentration of ferrous sulfate as well as that of oxygen; the concentration of free acid had a comparatively small influence, which in the case of sulfuric acid was to retard slightly the rate of reaction. More recently R. Thomas and E. T. Williams3 investigated the catalytic effect of nitric oxide on the oxidation of ferrous salts, which had been earlier patented by McCulloch.4 They found that the probable mechanism of the catalytic action was the oscillation of the catalyst between two stages of oxidation and its interaction alternately with the oxygen and the ferrous iron.

Jan 1, 1927

By Leo F. Reinartz

This is the fourth and final installment of Leo Reinartz' summation of the steelmaking industry over the first one hundred years. ALTHOUGH basic open-hearth steel has been in the limelight for many years, it has had to share some of its glory with two lesser but nevertheless important rivals, one 50 years old and one a rejuvenated process. Electric steel Electric-steel manufacture began in a humble way in the United States in 1906, when the first heat was tapped from a 3-ton Heroult electric furnace at the Halcomb Steel Co., Syracuse, N. Y. During the intervening years, it has completely eliminated the crucible process. For many years electric melting furnaces were located predominantly in relatively small, nonintegrated plants, making all kinds of high-grade alloy steels. Most of these furnaces, with capacities ranging from 5 to 20 tons, had basic bottoms. During and after World War II, many large basic electric furnaces, some up to 200 tons in capacity, were installed in integrated plants to make commodity steels. There were several reasons for building electric furnaces. Capital investment per annual ton of capacity was low and furnaces could be installed quickly. Since these furnaces used mostly scrap iron in the charge, no extra expensive coke- and blast-furnace capacity had to be added. The perfection of the top-charging design, and the development of large transformers and furnaces, made possible tons per hour as high as from modern 350-ton. open-hearth furnaces. Electric furnaces have high availability and repair costs are low. The process is flexible. Alloy and plain carbon steels of high quality can be made. Where power costs are low, the operating cost can

Jan 1, 1961

By R. R. Sayers

IT has long been common knowledge that workers in anthracite are prone to develop a disabling disease of the lungs. Some of the earliest scientific contributors dealing with anthracosis were: Pearson1, in his report in 1813, on the coloring matter of the bronchial glands and black spots in the lungs; Stratton2, in 1838, who first termed the condition anthracosis; Greenhow3, who reported to the pathological society in 1865, on the Black Lung of the Collier, and Pick4 in 1870, who reported on the chemical composition of the ash of a collier's lungs. Visconti5, in 1870, is accredited with being the first to use the term "silicosis" to denote the pathological condition of the lungs resulting from the inhalation of silica. Rovida6 confirmed the reports of Pick and Visconti in 1871, in his report on a case of silicosis and chemical examination of the lungs for silica content. The relationship of pulmonary infection, as associated with disabling pneumoconiosis affecting the coal miner, has frequently been discussed. While most reports have emphasized the role of infection, there has been some disagreement regarding the prevalence of tuberculosis among those suffering from anthracosis. The report by Wainwright and Nichols7 in 1905 has frequently been cited to show that the incidence of pulmonary tuberculosis among coal miners was -less than that among the general population. It was their opinion that pulmonary tuberculosis was more prevalent among the miners' families than among the miners themselves.. Collis and Gil-christ8, in 1928 in their study of the Effects of Dust upon Coal Trimmers, concluded that among such workers there was an excess of deaths from bronchitis and pneumonia but not from pulmonary tuberculosis. They

Jan 1, 1935

By F. Clerf

Blast-furnace practice in France is determined more or less by the character of the ores used. Some French ores are siliceous and others are calcareous, therefore by proper burdening a self-fluxing mix can be used. This is not always done, as, for instance, at the Caen furnaces of the Société Métallurgique de Normandie, where the Soumont ore of Normandy is used, which is a carbonate. This ore is crushed and calcined at the mines, yielding a product that is porous and well sized for blast-furnace consumption. The lines of the Caen furnaces are given in Fig. 1. Originally these furnaces had 16 tuyeres; six are plucked and these tuyeres are set in the lower part of the bosh. Operating data on these furnaces are given in Table 1. Table 1.—Operating Data, Caen Furnaces Kg. Lb. Blast-furnace burden per ton of iron: Soumont ore....................................... 200&2100 (44004650) Limestone...................................... 900-1000 (2000-2200) Basic Bessemer slag (bearing phosphorus).............. 100 (220) Scale.............................................. 35 (77) Manganese ores.................................... Coke.............................................. 1100-1200 (2420-2640) Coke analysis: Ash, per cent............. 9.5 H2O, per cent............. 4.0-10.0 Flue dust (approx.), kg. per metric ton.... 200 (440 lb.) Blast volume, cu. m. per hr.............. 83,000 (49,000 cu. ft. per min.) Preesure, lb............................ 12 Blast heat, deg. C....................... 650 (1200" F.) Top temperature, deg. C................ 250 (445O F.) Top-gas analysis, per cent............... CO2 9.3 CO 30.3 O2 0.3 H2 3.0 Production per 24 hr. about 510 tons. MINETTE ORES The most important ore deposits in France are in the west of Lorraine. They are called the "minette" ores and are of two classes-—siliceous and

Jan 1, 1937