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By W. F. Hosford

A quantitative explanation is offered for the peculiar curled grain shapes found in the microstructures of drawn wires of bcc metals and compressed aluminum specimens. It is shown that once an [011] fiber texture is developed, the slip system are so oriented that further slip tends to produce plane strain rather than axially symmetric flow of individual grains. With plane -strain flow, however, compatibility of neighboring grains can be maintained only by a bending of grains about one another. PROBABLY the most obvious microstructural feature of heavily worked metals is the distorted shapes of grains. In the course of deformation, the shape change of each grain must be compatible with that of neighboring grains; otherwise holes would be formed at grain boundaries. In analyses of poly-crystalline deformation by Taylor and subsequent workers it was assumed that grain boundary compatability was maintained by each grain undergoing the same shape change as the polycrystalline aggregate in which it is imbedded. According to this assumption, when simple tension or compression is applied to a random polycrystal or to one with a fiber texture, each grain ought to deform with axially symmetric flow. Initially equiaxed grains should become cigar-shaped during wire drawing and pancake-shaped during compression. While microstructural observations of deformed metals are generally in accord with such a picture, certain striking exceptions may be noted. Peck and Thomas5'8 found that grains in heavily drawn tungsten, iron, and niobium (columbium) wires become shaped like ribbons curled about the wire axis, Fig. 1. At a suggestion from the author, they rationalized the development of these micro-structures by considering the orientation of the slip systems in the [011] texture formed by the wire drawing. It is shown in this paper that marked departure from axially symmetric flow of grains is also observed when polycrystalline aluminum is severely compressed. Again the explanation must lie in the orientation of the slip system in the [011] texture, which is formed in fcc metals by compression.' THEORY A simple quantitative argument will be presented to show that the development of these microstructures is a result of flow on the combination of slip systems for which the minimum amount of mechanical work is expended in producing a unit tensile (or compressive) strain. First it must be realized that the macroscopic strains of a crystal resulting from slip are given by: where d dy, and dc, are normal strain increments parallel to the x, y, and z reference axes; are crystallographic shear-strain increments on slip systems

Jan 1, 1964

By R. F. Evans, J. M. Avery

MUCH has been written of the glamour of magnesium from sea water, the Aladdin-like creation of a huge magnesium plant in the Nevada desert using cheap hydroelectric power from Boulder Dam; the marvels of the Hansgirg process for the electrothermal reduction of magnesium oxide by carbon, and the ferrosilicon process for producing magnesium from dolomite. This is the story of the production of -magnesium by the electrolytic process, using steam-electric power supplied by a public utility, in a plant at Painesville, Ohio, 30 miles east of Cleveland on the shore 'of Lake Erie. The story is not without interest, since it involves several unique developments that provide the answer to a question frequently asked: How is it possible to produce magnesium metal economically at such a location as Painesville, Ohio? Basically, the answer lies in making use of facilities already in existence for the production of soda ash, which makes it possible to manufacture magnesium chloride, the principal raw material, cheaply enough to offset the high cost of electric power. To this is coupled the successful conversion of by-product chlorine into a product required for the war program. The source of magnesium for this operation is the enormous surface deposit of high-grade dolomite in the region south of Toledo, within reasonable freight haul of Painesville. This same geological stratum underlies the Painesville plant, but unfortunately at a depth of about 3000 ft. apparently too great a depth to permit underground mining to compete with the delivered cost of rock from surface quarries in other areas. The cost of dolomite obviously is an important factor, since the rock contains only some 12 per cent magnesium (20 per cent MgO) so that one dollar on the cost of stone means more than $8 in terms of its magnesium content, and more than that in terms of recoverable magnesium metal. PRODUCTION OF MAGNESIA FROM DOLOMITE In the summer of 1941, the Diamond Alkali Co. was well along with construction of a plant intended for the commercial production of refractory and other grades of magnesia from dolomite. The process to be used was designed to make maximum economic advantage of existing plant and operations by tying the production of magnesia in with the manufacture of soda ash in such a way as to make use of the lime (CaO) value of calcined dolomite. The process finally adopted after a lengthy research and development program has much in common with the old Clerc-Nihoul process, but includes certain innovations found to be necessary or

Jan 1, 1945

By R. A. Bergman, C. J. B. Fincham

THERMODYNAMIC properties of many high-temperature systems containing sulfur, such as slags, metal sulfides, and solutions of sulfur in liquid metals, have been studied by means of equilibration with known gas mixtures.'" This method presupposes a complete and accurate knowledge of the thermodynamic data for all possible components of the gas phase at high temperatures. However, a survey of the data available up to 1952 on the thermodynamics of gaseous sulfur species and compounds, by Richardson and Jeffes,' showed that there was considerable uncertainty in the values of the free energies of formation of S, SO, HS, and CS. In many cases, this uncertainty made it impossible to decide whether or not these species would form a significant proportion of the sulfur present in the gas phase in any given system. After the review by Richardson and Jeffes had been published, St. Pierre and Chipman6 measured, by an indirect method, the free energy of formation of SO. This also enabled a clear choice to be made among the three possible spectroscopic values for the dissociation energy of S2 into atoms10 thereby determining the free energy of formation of S from S2, and fixing the free energy of formation of HS more accurately" The main purpose of the present investigation was to measure the free energy of formation of CS, which was still in considerable doubt. For example, at 1600°C, it could be estimated to be +6 +25 kcal per mole,* most of the uncertainty being in the * Based on the dissociation energles of CS6 and S2,5 the heat of sublimation of graphite, and, the assumption that the entropy of formation of CS is the same as that of CO. value of the dissociation energy." A secondary purpose of the investigation was to determine more accurately the equilibrium sulfur pressures over dilute solutions of sulfur in carbon-saturated liquid iron. General Method Dilute solutions of sulfur in liquid iron, saturated with carbon, were brought to equilibrium at 1600" and 1800°C, with known gas mixtures consisting, initially, of A and CS2. After equilibrium had been reached, the melts were quenched and analyzed for sulfur. In the high temperature region of the furnace, an equilibrium was set up between the various possible sulfur species and compounds in the gas phase; namely, CS2, CS, S2, and S. (It can be calculated that the amounts of S6 and S, are negligible at these temperatures:) Morris and Bueh17 and Kitchener, Bockris, and Libermana had previously studied the corresponding

Jan 1, 1958

By Richard McCaffery

THERE has been some discussion among blast-furnace operators regarding the relative merits of tuyeres of the converging type and tuyeres designed in an attempt to produce a diverging jet of air. An article1 on Progress in German Blast Furnace Practice indicates the interest in this subject abroad. This article illustrates a diverging type of tuyere which is shown here in Fig. 1A. The design appears to be rather poor as regards known properties of air flow. The adoption of this. tuyere, the article states, resulted in a decrease of blast pressure of about 4 lb. per sq. in. and an increase of the output of the furnace. If the improvements mentioned are due entirely to the change in tuyere design, the subject of tuyere design seemed worthy of investigation and this paper is a report of such work. Because of the gain in efficiency brought about by the use of a diverging tuyere in the German plant, it was thought desirable to investigate the shape of the air streams issuing from various-types of tuyeres to ascertain whether the gain was due to the tuyere itself or to the distribution of the air in the furnace. Since it is difficult to do experimental work on a full-sized furnace, or even on full-sized tuyeres, and because of the equipment available for the work, it was decided to carry out the work on scale models of tuyeres. Therefore, in this work, single tuyeres were used and the blast discharged into the atmosphere. The shape of the air stream was determined by means of a Pitot tube suitably supported in the air stream at various positions. The air was. furnished by a Roots blower driven by a 10-hp. direct-current motor having field control, and capable of discharging 250 cu. ft. per min. with a pressure on the discharge of 4 in. of mercury. A modern blast furnace with 21-ft. hearth requires about 50,000 cu. ft. per min. of free air at from 16 to 23 lb. per sq. in. pressure, depending upon the type of burden. This pressure is the total pressure required to force the air through the burden and through the tuyeres. Upon computation the pressure drop through the tuyeres is about 1 to 2 lb. per sq. in. By making the tuyeres to a one-fifth scale, and by using a pressure of 1.5 in. of mercury, the shape of the air streams should be

Jan 1, 1931

By B. R. Coil, C. A. Ross

NEW demands for underground power in the Miami mine of the Miami Copper Co., Miami, Ariz. has brought about expansion of the distribution system for both ac and dc power. Progress in mining equipment and the normal changes in the mine were responsible for this increased demand. Early power requirements were for pumping and haulage. A 440 v ac power line down No. 5 shaft took care of a small pumping load and shaft station lighting, 275 v dc power was generated by motor generator sets on the surface, with a churn drill hole from surface to the 570 haulage level serving as a cableway. Electric lights were installed where power was available, and thus were confined to the haulage level and shaft stations. All industrial power in the Miami area is 25-cycle, which dates back to the hydroelectric generator installation at Roosevelt Dam in 1908-10. The Problem The main haulage level was moved to the 720 level and later, to the 1000 level, requiring a longer feeder line with the resultant voltage drop. Also, as mining progressed to the east, the churn drill hole for the power cable would have been subjected to subsidence cracks. The first extension in the use of electricity was in electric blasting. About 1935 the mine went to electric blasting, using the dc haulage current. Bringing electric current to the working levels of the mine for blasting greatly expanded the use of electric lights. Lights were used in tool rooms, powder and cap magazines, stairways, and other semi-permanent installations. Like all mines, Miami Copper began to study and experiment with mechanical mucking and transportation of ore by slushers, shakers, and belts during the late 1930's and early 1940's. At the beginning of the program, power was supplied from the haulage level 275 v dc system. Later it became necessary to run a cable, carrying 440 v ac power, down the No. 7 ventilation shaft. The increased use of power came about gradually, and many new problems were added, not the least being the introduction of switch boards and power cables into the working areas of the mine, where drifts and crosscuts take weight, and require repairs. The 25-cycle current presented special problems, in that 25-cycle transformers are twice as large and about 2V2 times as heavy as 60-cycle transformers of the same power output. The 25-cycle transformers were considered too large for installation in the mining areas. In 1947 the distribution system was revised and standards were adopted, governed by the following

Jan 1, 1952

Book Review Mexico, TODAY AND Tomorrow. By E. D. Trowbridge, Detroit. The McMillan Co., New York, 1919, 353 pp., 7;2 X 5 in. $2.00. The first eight chapters are devoted to an historical narrative of the Mexican peoples from the earliest times to the close of the war with the United States in 1345. "In dealing with events antedating what may be termed modern Mexico" the author has "made no attempt at original research, and so far as concerns anything prior to 1900, the work here presented is a repetition, a reflection, of the findings of opinions of Fiske, Prescott, Bancroft, Luis Perez Verdia and other authorities." The remainder of the hook deals with Mexico during and since the Diaz regime. It is interesting throughout but is not always convincing or consistent. Social conditions are described in a way illuminating and possible only to one who is familiar with the peon and his hitherto seemingly hopeless position in reference to the wage system and church oppression. In fact, the author makes the hold accusation that the "primitive rather than immoral" condition of the peons in the matter of their marital relations is due to the disregard of the church for their welfare and capabilities. The true accounts of the Madero revolution and the Huerta regime read like fascinating medieval fiction. The reason given for men remaining in the Madero army is still the controlling one regarding any of the armies there. "They had horses, arms, all the food they wanted, money to spend and no work." The discussion of Mexican financial schemes is wholly from the Carranza viewpoint. To meet a monthly deficit of ten million pesos the author says "the government forced loans from the National Bank, and Bank of London and Mexico, and repeated the operation several times, finally practically exhausting their bullion and cash reserves. Hostile foreigners refer to this operation as the looting of the hanks! Drastic as this action was, there was good ground on which to justify it." However, that necessity knows no law is never an acceptable tenet except to him who applies the screws. The discussion of the economic problems and their solution is rather chimerical and presupposes a civil and national virtue in the present government not discernible except to one ultra friendly. The book is an interesting exposition of the very much involved situation from the viewpoint of approval of both the Carranza government and the attitude of the United States in its dealings with him. The editing of the book leaves something to he desired. P. E. B.

Jan 9, 1919

By H. A. Wheeler

That lead and zinc deposits are the result of prolonged,, slow deposition is the idea of most students of ore deposits, and in many cases, where the ore-bearing solutions have been very weak or the precipitating conditions have been very feeble, the ore accumulations have undoubtedly taken a long period of time. As these two vital conditions have been subject to great variations in the different mining camps, the following example is highly interesting in showing that deposition can be very rapid under favorable conditions, geologically speaking, and also extremely recent. In fact, the writer is inclined to regard most, if not all, of the Mississippi Valley deposits of lead and zinc as probably being very young, at least not older than Tertiary, if not Quarternary, in age. The extensive Joplin lead and zinc district, in southwestern Missouri, which is about 60 years old and has numerous mines that were abandoned from 1 to 50 years ago, shows that the lead and zinc today are in an active condition of solution and redeposition, although these two metals occur in the predominant form of sulfides. The mine waters from the older and more or less abandoned portions of the district are frequently so acid, mainly from the oxidation of associated pyrite, as to necessitate the use of wooden pipes and pumps. The first boom in the Oklahoma zinc fields, which is the southwestern extension of the Joplin district, occurred when ore was accidentally struck in drilling a water well. Among the mines then opened up was the Mission mine, at Lincolnville, Ottawa County, Okla. This mine was opened in 1903 in lean "sheet ground," or a flat blanket formation of chert carrying disseminated zinc blende, or "jack," and galena. Theore-body was very free from iron pyrites and the concentrates were very high grade, the "mineral," or lead concentrates, assayed 80 to 85 per cent. lead and the jack, or sphalerite, assayed 60 to 65 per cent. zinc. The orebody was very shallow, occurring at a depth of 76 to 95 ft. (22 to 28 m.) and very wet, requiring three or four pumps to handle the water. The mine was operated until 1914, when it was closed by litigation and immediately filled with water. The second Oklahoma boom, five years ago, opened up the large, active camps of Picher, Tar River, and Century, which are located 2 to 5 mi. west of Lincolnville. They are considerably deeper, being farther down on the westwardly dipping monocline that emanates from the Ozark

Jan 1, 1920

By Louis V. Bender

AfteR investigating the work of coal-dust fired reverberatories of the Canadian Copper Co., at Copper Cliff, Ontario, the management of the Washoe Reduction Works decided to experiment with and ascertain the advantages of using coal dust as a fuel in their reverberatories. Consequently, during the month of June, 1914, reverberatory furnace No. 8 was changed in order to use powdered coal as a fuel. The results obtained by this method of firing are gratifying and show a decided saving in cost of smelting as compared to grate firing with lump coal. The furnace, as remodeled, is 124 ft. long by 21 ft. wide, and varies in height from 8 ft. 6 in. at the back end to 5 ft. 7 in. at the skimming end. The general construction of the furnace is similar to that of the other furnaces at this plant. There are no side doors to this furnace, as it was thought that with the present arrangement for feeding no "fettling" or "claying" would be required. The interior of the furnace can be inspected through the burner port holes, after shutting off the burners and giving a few seconds' time for the gases inside the furnace to clear away. The charging is done on either side of the furnace from longitudinal hoppers, extending a distance of 74 ft. from the back end of the furnace. Leading from the hoppers into the furnace are 6-in. pipes, spaced 191/4 in. apart, through which the charge is intermittently dropped. The charge is kept well above the slag line at all times; in this way the side walls are protected and no fettling is needed on this portion of the furnace. The remainder of the furnace requires fettling. After operating for three months, we found that the bricks were eaten into along each side wall from the skimming door back to the point where the charge had been dropped. The depth of this cutting away was 8 in. close to the front end and gradually tapered to zero at a distance of 50 ft., and was greatest on the side of the furnace having the larger flue connection. Hoppers will be put in for the entire length of furnace, from which fettling material will be dropped, to prevent this cutting. After the run of three months, the roof was in excellent condition. At the back of the furnace the bricks were not cut into at all; at 30 ft.

Jan 1, 1915

By Philip S. Morse

THE Australian lead-smelting plants began to use charges carrying high zinc percentages somewhat earlier than was common with American plants. When lead smelting first started in Australia the immense deposits of oxidized lead at Broken Hill were available but later these oxidized ores became exhausted and were replaced by sulfides. This was before the days of flotation and these sulfides when concentrated carried about 1 per cent. of zinc to 6 per cent. of lead. The works of the Sulphide Corpn. at Cockle Creek was perhaps the pioneer in high-zinc slags but the Port Pirie plant of the Proprietary Co. was a close and very able second and has continued the work to the present time. The Cockle Creek lead furnaces remained in operation until shortly after the war when most of the Broken Hill companies combined and took over the Port Pirie plant to treat their concentrates. As it was the practice both at Cockle Creek and Port Pirie to carry 20 per cent. or more of lead on the charge, it was found that under these conditions of large amounts of zinc in the charge, good roasting was absolutely necessary and matte production was unwise. The Hunting-ton-Heberlein system of roasting was introduced and later the Dwight & Lloyd process. In this way, by roasting the sulfide portions of the charge as thoroughly as possible and making no matte, a method of smelting was developed where the slag over long periods carried as high as 20 per cent. ZnO without serious furnace troubles, and slags carrying even up to 33 per cent. ZnO have been reported. The zinc slags were not very different in appearance from the ordinary slags produced in American practice except that they gave off more smoke and fume on tapping. The slag usually ran hot and freely, coming from the tap in a full stream. Normally there was little crust on the sides of the furnace and the tuyeres gave no trouble though they were always rather dark. At the works of the Sulphide Corpn. it was the custom, on account of the labor situation, to shut down the furnaces during the Christmas holidays, thus giving a campaign of about 12 months. The furnaces at the end of the run usually showed no crust on the sides, though crusts always occurred at the back and front ends. A furnace campaign of 22 to 23 months has been made at this plant where both sides of the

Jan 1, 1929

By W. A. Ver Wiebe

The year 1939 in Kansas, with a production of 57,944,300 bbl. from 19,669 wells, shows a slight recession from the peak of oil production reached the previous year, when slightly over 59,000,000 bbl. of oil was marketed. The previous peak had been reached in 1917 with 45,451,000 bbl. marketed. Another still earlier peak had been reached in 1904, when slightly less than 5,000,000 bbl. was produced and sold. The production of gas probably reached a new peak during 1939 with a total of over 69 billion cubic feet. Between the peak of the year 1908, when over 80 billion cu. ft. was produced, and that of 1939 the production dropped to 16 billion cu. ft., in the year 1921. During the year 1458 wells were drilled. This figure is somewhat lower than that given in several trade journals, because it does not include wells that were deepened or recompleted in a different geological horizon. Nearly 75 per cent (1029) of the total number of wells were completed as commercial oil wells (824 in western and 205 in eastern Kansas). The commercial gas wells completed number 71, of which 24 are in eastern Kansas and 47 in western Kansas. The remaining completions include 154 dry holes in eastern and 204 dry holes in western Kansas. Based on daily potential capacity the new discoveries of the year accounted for a cumulative initial production of 264,000 bbl. in eastern and 1,158,827 bbl. in western Kansas. It is interesting in this connection to note that the number of wells completed in the state rose gradually to a first peak in 1904, when 2782 were drilled. The number dropped off rapidly to 368 three years later, but rose to the second and highest peak in 1918, when 4671 wells were completed. In the period between 1904 and 1912 more gas wells than oil wells were completed. Between the high peak of 1918 and the somewhat lower peak of 1937, the low point was reached during 1931 with the completion of only 470 wells. In the matter of new pools discovered, Kansas again ranks high. The exact number depends somewhat upon the interpretation of a "new" area—whether it should be called a new pool or a long extension of an older pool. In some places this determination cannot be made until more wells are drilled within the area. Therefore, the figures given

Jan 1, 1940

By W. A. Ver Wiebe

The year 1939 in Kansas, with a production of 57,944,300 bbl. from 19,669 wells, shows a slight recession from the peak of oil production reached the previous year, when slightly over 59,000,000 bbl. of oil was marketed. The previous peak had been reached in 1917 with 45,451,000 bbl. marketed. Another still earlier peak had been reached in 1904, when slightly less than 5,000,000 bbl. was produced and sold. The production of gas probably reached a new peak during 1939 with a total of over 69 billion cubic feet. Between the peak of the year 1908, when over 80 billion cu. ft. was produced, and that of 1939 the production dropped to 16 billion cu. ft., in the year 1921. During the year 1458 wells were drilled. This figure is somewhat lower than that given in several trade journals, because it does not include wells that were deepened or recompleted in a different geological horizon. Nearly 75 per cent (1029) of the total number of wells were completed as commercial oil wells (824 in western and 205 in eastern Kansas). The commercial gas wells completed number 71, of which 24 are in eastern Kansas and 47 in western Kansas. The remaining completions include 154 dry holes in eastern and 204 dry holes in western Kansas. Based on daily potential capacity the new discoveries of the year accounted for a cumulative initial production of 264,000 bbl. in eastern and 1,158,827 bbl. in western Kansas. It is interesting in this connection to note that the number of wells completed in the state rose gradually to a first peak in 1904, when 2782 were drilled. The number dropped off rapidly to 368 three years later, but rose to the second and highest peak in 1918, when 4671 wells were completed. In the period between 1904 and 1912 more gas wells than oil wells were completed. Between the high peak of 1918 and the somewhat lower peak of 1937, the low point was reached during 1931 with the completion of only 470 wells. In the matter of new pools discovered, Kansas again ranks high. The exact number depends somewhat upon the interpretation of a "new" area—whether it should be called a new pool or a long extension of an older pool. In some places this determination cannot be made until more wells are drilled within the area. Therefore, the figures given

Jan 1, 1940

By Frank H. Macpherson

When it became apparent early in 1941 that the United States might be drawn into the war, studies were made of the bauxite situation in Arkansas, principally because 9.5 pct of the known bauxite reserves of the country were located in that State. Bauxite mining was then geared for maximum production to supply ore to meet this country's war requirements and, if necessary, to supply the needs of Canada as well. In view of the comparatively small bauxite reserves, Congress appropriated funds for an extensive exploratory drilling program to be carried out by the Bureau of Mines in cooperation with the Geological Survey. An alumina plant was erected near Bauxite and an aluminum plant near Hot Springs, Ark., by the Defence Plant Corp. The Metals Reserve Co. established a schedule of prices, arranged for stockpile sites and a buying agency. Operators cooperated to step up production and new ones came into the field. Production Record Prior to 1941, the greatest annual production in Arkansas was 562,892 long tons, dry basis in 1918. During the single month of August 1943, 693,596 long tons were mined—130,704 tons more than for the entire year of 1918. In general the Arkansas bauxite deposits are relatively small, irregular in thickness, somewhat scattered and, compared to coal, iron or open-pit copper deposits, are ill-adapted to an expansion in output. Commercial deposits range in horizontal extent from less than an acre to about 40 acres and are usually very irregular in outline. The average thickness of all known workable deposits is between 12 and 15 ft. with a maximum of about 60 ft. The ore bodies are usually somewhat undulating and nearly horizontal although locally some deposits dip as much as IS°. Types of Bauxite Three physical types of bauxite may be recognized: pisolitic, granitic and amorphous. Pisolitic ore is the most common type. It consists of small pebble-like nodules, ranging from the size of a pin head up to several inches in diameter, all set in a fine grained matrix. Transported bauxite is usually- pisolitic. Most residual bauxite is granitic. It is believed not to have moved appreciably from the location where it originally was formed. This is indicated by the fact that it appears to grade into unaltered nephelite syenite, which it overlies. Amorphous ore is the least abundant. It is nonpisolitic and resembles clay, has no characteristic texture, and can be identified definitely only by chemical analysis. Uses of Bauxite Bauxite is chiefly used for, and at the present time is substantially the only

Jan 1, 1948

By Frank H. Macpherson

When it became apparent early in 1941 that the United States might be drawn into the war, studies were made of the bauxite situation in Arkansas, principally because 9.5 pct of the known bauxite reserves of the country were located in that State. Bauxite mining was then geared for maximum production to supply ore to meet this country's war requirements and, if necessary, to supply the needs of Canada as well. In view of the comparatively small bauxite reserves, Congress appropriated funds for an extensive exploratory drilling program to be carried out by the Bureau of Mines in cooperation with the Geological Survey. An alumina plant was erected near Bauxite and an aluminum plant near Hot Springs, Ark., by the Defence Plant Corp. The Metals Reserve Co. established a schedule of prices, arranged for stockpile sites and a buying agency. Operators cooperated to step up production and new ones came into the field. Production Record Prior to 1941, the greatest annual production in Arkansas was 562,892 long tons, dry basis in 1918. During the single month of August 1943, 693,596 long tons were mined—130,704 tons more than for the entire year of 1918. In general the Arkansas bauxite deposits are relatively small, irregular in thickness, somewhat scattered and, compared to coal, iron or open-pit copper deposits, are ill-adapted to an expansion in output. Commercial deposits range in horizontal extent from less than an acre to about 40 acres and are usually very irregular in outline. The average thickness of all known workable deposits is between 12 and 15 ft. with a maximum of about 60 ft. The ore bodies are usually somewhat undulating and nearly horizontal although locally some deposits dip as much as IS°. Types of Bauxite Three physical types of bauxite may be recognized: pisolitic, granitic and amorphous. Pisolitic ore is the most common type. It consists of small pebble-like nodules, ranging from the size of a pin head up to several inches in diameter, all set in a fine grained matrix. Transported bauxite is usually- pisolitic. Most residual bauxite is granitic. It is believed not to have moved appreciably from the location where it originally was formed. This is indicated by the fact that it appears to grade into unaltered nephelite syenite, which it overlies. Amorphous ore is the least abundant. It is nonpisolitic and resembles clay, has no characteristic texture, and can be identified definitely only by chemical analysis. Uses of Bauxite Bauxite is chiefly used for, and at the present time is substantially the only

Jan 1, 1948

By R. F. Evans, J. M. Avert

Much has been written of the glamour of magnesium from sea water, the Aladdin-like creation of a huge magnesium plant in the Nevada desert using cheap hydroelectric power from Boulder Dam; the marvels of the Hansgirg process for the electrothermal reduction of magnesium oxide by carbon, and the ferrosilicon process for producing magnesium from dolomite. This is the story of the production of magnesium by the electrolytic process, using steam-electric power supplied by a public utility, in a plant at Painesville, Ohio, 30 miles east of Cleveland on the shore of Lake Erie. The story is not without interest, since it involves several unique developments that provide the answer to a question frequently asked: How is it possible to produce magnesium metal economically at such a location as Painesville, Ohio? Basically, the answer lies in making use of facilities already in existence for the production of soda ash, which makes it possible to manufacture magnesium chloride, the principal raw material, cheaply enough to offset the high cost of electric power. To this is coupled the successful conversion of by-product chlorine into a product required for the war program. The source of magnesium for this opera- tion is the enormous surface deposit of high-grade dolomite in the region south of Toledo, within reasonable freight haul of Painesville. This same geological stratum underlies the Painesville plant, but unfortunately at a depth of about 3000 ft.— apparently too great a depth to permit underground mining to compete with the delivered cost of rock from surface quarries in other areas. The cost of dolomite obviously is an important factor, since the rock contains only some 12 per cent magnesium (20 per cent MgO) so that one dollar on the cost of stone means more than $8 in terms of its magnesium content, and more than that in terms of recoverable magnesium metal. Production of Magnesia from Dolomite In the summer of 1941, the Diamond Alkali Co. was well along with construction of a plant intended for the commercial production of refractory and other grades of magnesia from dolomite. The process to be used was designed to make maximum economic advantage of existing plant and operations by tying the production of magnesia in with the manufacture of soda ash in such a way as to make use of the lime [CaO)., value of calcined dolomite. The process finally adopted after a lengthy research and development program has much in common with the old Clerc-Nihoul process, but includes certain innovations found to be necessary or advantageous. Essentially, the process is based upon the following series of reactions:

Jan 1, 1949

Book Review MAN-TO-MAN: THE STORY OF INDUSTRIAL DEMOCRACY. By John Leitch, Phila¬delphia, Pa. The B. C. Forbes Publishing Co., New York, 1919, 2.19 pp., 7 1/2 X 5 in. $2.00. "Man to Man" is a short, well-written, well-printed, easy to read and very interesting hook. It is an account of a method introduced into more than twenty industrial plants to give the workers a share in managing their own troubles. It is not a panacea for labor troubles and strikes, but neither have existed where the new method has been tried. The scheme is, in a word, to organize the working force like the government, having a cabinet composed of the executives, a senate composed of foremen, and a house composed of men elected by fellow workers from all departments. This governing machinery takes up all complaints of workers, investigates, reports, and settles. The increased profits due to economy and increased production from this cooperation are divided 50-50 between the company and the men. Experience has shown that, since inattention, tardiness, irregularity, and inefficiency tend to reduce their profits, all men very quickly, after once convinced of the sincerity of the management in their scheme of cooperation, eliminate them because it is for their personal profit. Astonishing results have been attained, including higher wages, greater output, lower unit costs, great reduction in labor turnover, elimination of waste, an increased loyalty and a waiting list of employees even in periods of labor shortage. Profit sharing as such and stock ownership as a benefit to industrial relations are discussed briefly and illuminatingly, although they are not believed by the author to he the best way to bring about the human relation between those who work,for and those who work with money. The author is not against unions but does not believe the union is the best medium for improving industrial relationship. The look is nowhere dogmatic but is always forceful and convincing and, being well written, is very entertaining. It is doubtful if "Industrial Democracy" is the right expression for the solution of the problem but certainly anything that will place on the shoulders of labor some of the responsibility of industry and will increase production is tine much-to-be-desired desideratum. It is a. contribution to the solution of our biggest problem and should be read by everyone who employs men and who has been worried by the labor turnover. P. E. B.

Jan 7, 1919

By Walter R. Hibbard, Walter L. Finlay

INTRODUCTION THE key feature of the lattice coherency theory of precipitation hardening1-6 is the forced coherence between matrix and precipitate which elastically strains both lattices and is believed to be the major source of strengthening in precipitation hardening. In systems exhibiting age hardening, the atom movements leading to precipitation are not at all extensive and are such as to require the minimum amount of energy to produce the interface; that is, the new lattice forms in such a way as to be as nearly as possible a continuation of the old with a matched, coherent plane at the interface at least during the initiation of the precipitation. The crystallographic sequence whereby regions of the matrix change to the precipitate lattice usually can be resolved into a set of shearing operations.5,6 Conversely, the perhaps novel speculation is made that solution of a second phase is accompanied by shearing movements which are possibly the reverse of the precipitation shearing movements. A basic premise of the investigation reported in this paper is that precipitation and solution shearing movements constitute structural weaknesses which might cooperate with applied stresses to facilitate plastic deformation. Another basic premise of the investigation is that the application of hydrostatic pressure to a precipitation hardening system will significantly alter the degree of disregistry across the matrix-precipitate interface and thereby significantly affect the course of age hardening. Two binary precipitation hardening systems were investigated: 12 pct zinc in aluminum which undergoes transformations, both precipitation and solution, by a simple crystallographic mechanism; and 4 pct copper in aluminum which undergoes a complex transformation in precipitating and dissolving a second phase. The effects of the application of uniaxial tensile creep stress during elevated temperature aging of both systems and of hydrostatic pressure during the elevated temperature aging of 12 pct aluminum-zinc were then investigated. Previous Investigations Van Wert in 1935,7 studied the effect of hydrostatic pressure on the room temperature age hardening of a few precipitation hardening systems. The latter were rather unfortunately selected since none is known to exhibit any marked volume change on aging and the majority were complex commercial alloys the precipitation mechanisms of which are not known. Jenkins, Bucknall and Jenkinson,8 in 1944, applied tensile creep stresses to a complex coppernickel-silicon alloy at various temperatures. The complexity of the alloy and the industrial objective of the work did not permit an appreciable addition to the theoretical understanding of either deformation or precipitation hardening.

Jan 1, 1948

By E. S. Wheeler

The conversion plant of the Clirnax Molybdenum Co. is at Langeloth, Washington . County, Pennsylvania, approximately 30 miles west of Pittsburgh. The molybdenite concentrates converted originate in the company's mine and mill at Climax, Co1orado.l They are delivered to the Langeloth plant by rail packed in 175-lb. bags. War production of concentrates at the mill started in 1918 but it was not until about 1920 that any peacetime uses of the metal began to develop. Early conversion of Climax concentrates was mainly into ferromolybden um, produced for the company by a custom smelter. Chronology of Plant Development In 1924 a small hand-rabbled roaster was built at Langeloth, the roasted concentrates being used principally in the production of calcium molybdate by a conventional wet method. The size of the original plant is indicated by the fact that during 1925 about 400,000 lb. of molybdenum was converted. In 1925-1926, a multiple-hearth roaster was erected (12-ft. 0.d. 8-hearth Nichols-Herreshoff); also the first experimental ferromolybdenum was produced at Langeloth. At this time sa.1cium molybdate was produced in the furnace by a process to be described. With continued interest in and increased use of molybdenum, it was necessary to arrange for enlargement of plant facilities. Although only one 12-hearth 16-ft. 0.d. roaster was erected at this time (1929), plans were prepared for a duplicate unit, which was completed in 193 5, giving a potential roasting capacity of some 16,000 lb. Mo per day under the then prevailing roasting practice. Shortly after this second unit had gone into production, increased demand overtaxed the plant, and as a result two 12-hearth 18-ft. 0.d. roasters were placed in operation in 1936 and 1937. This gave the plant a potential roasting capacity of 40,000 to 50,000 lb. Mo per day, and necessitated major changes in auxiliary handling equipment as well as improved facilities for producing ferromolybdenum. Following the introduction (1938) of a new product—molybdic oxide briquets— and because of the constantly growing demand for molybdenum, plant facilities were again enlarged in 1940 and 1941 by the erection of two 16-hearth 18-ft. 0.d. roasters. These two new units, along with a change in roasting practice, brought the potential roasting capacity to 150,ooo to 190,000 Ib. Mo per day, based on about 15 lb. per sq. ft. of hearth area. Other departments of the plant have necessarily grown, until today the plant is modern throughout and completely mechanized, with equipment geared to produce marketable products as follows:

Jan 1, 1944

By John P. Bryant, Samuel Kincheloe

Plant nutrients are obtained by plants from both the air and the soil. Carbon dioxide, a gaseous form of carbon and oxygen, supplies the carbon which usually makes up 50% or more of plant structure. Plants are capable of absorbing carbon dioxide directly from the air. Most of this nutrient comes from the air, although some carbon dioxide is absorbed by soil water and taken into the plant as liquid. Growing plants use more water than any other substance. Plant nutrients in the soil dissolve in soil water; soil water entering the plant carries nutrients into the plant structure. Water is then given off into the air as the plant breathes or transpires. Inorganic or mineral nutrients essential to plants are supplied through the soil. Inorganic or mineral composition of plants usually is less than 5% of their weight. In most crop-growing areas, much of this nutrition is inadequately supplied from the soil and must be provided by fertilizers. Proper fertilization of a soil to improve its mineral level and productivity is the role of the fertilizer industry. The 13 essential plant nutrients which often must be added to soils or plants and are generally considered fertilizer minerals are categorized as primary minerals (nitrogen, phosphorus, and potassium); secondary minerals (calcium, magnesium, and sulfur); and micronutrients, or trace minerals (boron, iron, manganese, copper, zinc, molybdenum, and chlorine). These classifications are based on quantity of nutrients utilized by plants and have no implication as to function or degree of necessity. One point of major significance to the fertilizer industry is that not all nutrient carriers supply that nutrient in a chemical form which will be available to the plant. Thus, a product which may be considered a fertilizer mineral may require substantial processing or may require substantial processing or treatment before it becomes useful as a nutrient carrier. Fertilizer Industry Scope Until about 1900 demands for higher crop yields were met simply by bringing new agricultural lands into cultivation. Since that time great progress has been made in increasing yields through fertilization and improved varieties and cultural practices. The importance of the fertilizer industry to the economy and welfare of the US is widely recognized. Fig. 1 illustrates the relationship of lime and fertilizers to crop yields. In terms of tons of fertilizer products, the growth of the industry has been phenomenal, particularly between 1950 and 1980. Table 1 shows the increase in fertilizer usage. Primary Plant Nutrients in Fertilizers Primary minerals (nitrogen, phosphorus, and potassium) are designated as such because [ ]

Jan 1, 1983

Frontino operates three underground lode mines at Segovia in the area of northwest Antioquia, Colombia, which has been an important gold producing district since the late 1800s. Auriferous pyrite, the pre-dominent sulfide, carries very finely disseminated gold. Other minor sulfides are galena, pyrrhotite, and sphalerite in quartz gangue with the host rock being granodiorite. Silver is associated with the galena and also occurs as a sulfo-salt. In 1.973 and 1974, at an annual milling rate of 145,000 mt (160,000 st), average mill heads were 7.80 g per mt (0.23 oz per st) Au; 20.0 g per mt (0.58 oz per st) Ag; and 0.37% Pb; with a production of 1,150 kg (35,700 oz) Au and 4,500 kg (141,000 oz) Ag. Over 300 mt (330 st) of Pb concentrate were shipped. The ore is crushed to minus 16 mm (5 18 in. ) and fed to a rod mill with the discharge passing over a 1.07 m by 1.07 m (42 in. by 42 in. ) jig operating in closed circuit with the underflow from a cyclone in closed circuit with two ball mills. Cyclone overflow is bulk-floated for sulfide recovery from which the tailings are sent to the river as waste with the flotation concentrate joining the jig concentrate for cyanidation. The combined gold bearing concentrates, after cyclone classification, are reground to a very fine mesh in closed circuit with cyclone classification, with the overflow going to the primary thickener. Regrinding, classification, and thickening is done in cyanide solution, and the primary thickener produces a pregnant solution for Merrill -Crowe precipitation. The thickener underflow is the feed to the agitators, thickener, and filter from which the overflow and filtrate are sent to precipitation. The washed filter cake is repulped and floated for the recovery of a galena concentrate for shipment. About 40% of the recovered silver is in this concentrate. In the refinery the precipitate is melted into a dore bullion. This 600 mt (660 st) capacity mill employs several interesting techniques. Gold recovery of 85% to 90% from a complex sulfide denotes good practice. While total power at 42 kwh per mt (46 kwh per st) is high, it would be recognized that the grinding units are small in size and the flowsheet is complicated due to the gold occurring in the sulfide minerals. The extremely low-cost electric power is generated by

Jan 1, 1981

By D. B. Jugle, J. B. Darby, O. J. Kleppa

A systematic study has been made of the kinetics of solution under steady state, dynamic conditions of titanium, vanadium, chromium, iron, cobalt, and nickel in liquid aluminum. It was found that the temperature dependence of the solution rate obeyed an Arrhenius-type rate equation, and that at a given temperature the rate of solution of the various solutes correlates quantitatively with the equilibrium solubility of the solute in liquid aluminum. These results are consistent with a mechanism where the rate-controlling step is the diffusion of solute atoms through a liquid boundary layer. THE present study was initially started in order to explore the feasibility of liquid-metal solution calorimetry for transition metals and alloys. Previous work1 in this field employing liquid tin as a solvent at temperatures in the 500' to 600' range had indicated that the rates of solution of most transition metals in tin are very low. Under such conditions effective solution calorimetry is difficult. The objective of the present investigation was two-fold: a) To obtain, as far as possible, quantitative data on the rates of solution of a series of transition elements in liquid aluminum. b) To explore whether liquid aluminum might be a suitable solvent for liquid-metal calorimetry. In the course of this work a comprehensive set of data was obtained on the steady state rates of solution of transition metals in a common liquid-metal solvent. The results are consistent with the boundary layer model, which assumes that the rate-controlling step consists of diffusion of solute atoms through a viscous liquid layer. EXPERIMENTAL PROCEDURE A vacuum-tight stainless steel vessel was surrounded by a resistance furnace, as shown in Fig. 1. In all experiments the temperature of the liquid solvent was controlled to 2.5' by means of a Micromax controller. A high-vacuum manifold connected to the vessel maintained a vacuum of 1 x 105 mm of Hg or better. The vacuum vessel was equipped with a charging section isolated from the working chamber by a vacuum-tight gate valve. This arrangement allowed the specimen holder to be removed or inserted into the apparatus without removal of the liquid metal bath. The specimen holder was suspended from a closed end stainless steel tube, which also served as the thermocouple protection tube. The portion of the tube that was below the solvent level was surrounded by an alumina protection tube to isolate it from the liquid metal bath. The stainless steel tube was connected through a rotary vacuum seal and a gear train to a fractional horsepower motor. For most experiments the tube was rotated at a constant

Jan 1, 1963