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By J. T. Williams

The equilibria in the V-Zr alloy system were investigated by solidus temperature determinations, thermal analysis, dilatometry, electrical resistance measurements, microscopic examination, and X-ray diffraction analysis. There is a eutectic reaction at 1230°C between a compound, V2Zr, and a solid solution containing 10 pct V in ß zirconium. V2Zr decomposes at 1300°C into liquid and a solid solution containing about 10 pct Zr in vanadium. The eutectic composition is probably about 30 pct V. A eutectoid reaction between V2 Zr and a zirconium takes place at 777°C at a very high rate. The eutectoid composition is 5 wt pct V. The limit of solubility of zirconium in vanadium was estimated to be 5 pct at 600°C. No attempt was made to determine the liquidus for the system. THE recent availability of large quantities of high purity zirconium has stimulated the study of zirconium binary systems. The equilibrium diagram for the V-Zr system has received little attention, however. Wallbauml appears to have made the first report concerning the equilibria in these alloys. He reported the existence of a compound, V2Zr, having the MgZn2 ((214) type of structure with a, = 5.277 kX and c° = 8.647 kX. Anderson, Hayes, Roberson, and Kroll2 made a survey of some potentially useful zirconium binary alloys and found that zirconium probably dissolves a small amount of vanadium. They reported the probable existence of a compound between the two elements and suggested that the zirconium-rich solid solution undergoes a eutectic reaction with this compound. Pfeil," in a critical review of the existing information, estimated that the solubility of vanadium in zirconium is less than 4.7 pct and probably less than 1.8 pct. Rostoker and Yamamoto' proposed a partial diagram for the V-Zr system in a survey paper on vanadium binary alloys. Their diagram indicates the compound, V,Zr, a eutectic reaction at 1360°C, a peritectic reaction at 1740°C, and a limit of solubility of zirconium in vanadium of about 3 pct. They obtained no information on the equilibria in the zirconium-rich alloys. In view of the potential utility of the V-Zr alloys and the incomplete knowledge concerning the equilibria in the system, an attempt was made to establish the constitutional diagram. Preparation of the Alloys Raw Materials: The vanadium for making up these alloys came from the Electro Metallurgical Corp. Zirconium came from two sources. In the beginning of the investigation, sponge zirconium from the Bureau of Mines was used in making some of the alloys. Later, iodide metal made at the Westinghouse Atomic Power Development Laboratories became available. This material was used in the preparation of all the dilatometric and resistance specimens and about two-thirds of the solidus temperature specimens. A typical manufacturer's analysis of the vanadium is shown in Table I. No other analysis of the vanadium was made. The metal contained a dispersed second phase and did not have a sharp melting point. Typical results of spectrographic analysis of the Westinghouse zirconium are shown in Table 11. These data indicate a very high purity. The Bureau of Mines sponge metal was probably less pure but had good ductility. Melting: All of the alloys used in the investigation were made by melting pieces of vanadium and zirconium together in a dc electric arc furnace similar to those of Geach and Summers-Smith, craighead, Simmons, and Eastwood," and others. Melting was done in an atmosphere of helium scavenged of residual air by the preliminary melting of a separate charge of zirconium. Each ingot was turned over and melted at least three more times before removal from the furnace to aid in the attainment of homogeneity. Alloys prepared for use in the investigation are listed with the results of solidus determinations in Table III with the exception of the following compositions upon which no solidus determinations were made: 0.29, 0.54, 4.57, and 5.55 pct V. Analysis: The weight of each ingot made from iodide zirconium was within 0.1 g of the total weight of the initial charge, about 90 g. Since each component of each charge was weighed to the nearest 20 mg for amounts less than 10 g and to the nearest 0.1 g otherwise, the gross composition of an ingot could be calculated accurately. Chemical analysis for the vanadium content of several alloys agreed

Jan 1, 1956

By Frank Firmstone

In April, 1873, No. 2 furnace at the Glendon Iron Works being out of blast, it was decided to alter it from an open to a closed top. The three side flues, through which a part of the gas was formerly taken off, were 15 feet below the top, and as, for various reasons, it was not convenient to cut new flues through the brickwork at the top, as is commonly done with closed-top furnaces, a modification of Coingt's charger was employed. This apparatus, as figured by De Vathaire,* consists of a cup or hopper, like that used with the cup and cone, and a central pipe for taking off the gas, which descends some distance into the furnace, and has a projection around it forming a seat for a ring of a triangular cross-section, which closes the opening between the cup and the central gas-pipe. The charge is put into the cup, and by lowering the ring, is thrown into the furnace, a part going outside of the ring toward the walls, and a part through the inside toward the gas-pipe. In this form the apparatus was not applicable, for: 1st. With a gas-pipe three feet in diameter, in a top eight feet in diameter, the openings left by lowering the ring would not be large enough to let lump coal pass through. 2d. For the charger to shut tight, the ring must bear equally against the projection made for it on the gas-pipe, and against the edge of the cup. This would not be difficult to effect when the apparatus is first put up, but a comparatively small change in the relative position of the parts, such as is almost certain to occur from expansion, would cause the ring to touch the pipe or the cup, whichever happened to be the lower, first, and leave a leak between it (the ring) and the other. In the plan adopted (Figs. 5 and 6, Plate I), the central opening in the ring is closed by the bottom of the gas-pipe, whereby more room is left for the passage of the stock when the charger is open, than if the pipe descended into the furnace; and the pipe, instead of being rigidly supported, rests on the ring, when the charger is closed, and follows it for two or three inches as it opens, until stopped by the counter-balance lever C. When the ring is raised to close the furnace top, it comes in contact first with the bottom edge of the gas-pipe, then both are raised together, until stopped by the ring touching the edge of the cup. In this way a good joint is made at both places.

By W. J. Romanow

RECENT papers by Williams, Sherwood, and Boothby,1 Seybolt et al.2 Heikes; and Roberts4 attest to the increasing importance of the hexagonal ferromagnetic compound MnBi. Since the magnetic properties of MnBi crystals are highly anisotropic, it is useful and necessary to have appropriate aids for determining their orientations—a (00.1) standard stereographic projection and a corresponding table of crystallographic angles for this structure. The tables of crystallographic angles for the hexagonal system available in the literature5 are computed for c/a ratios greater than that of MnBi and cannot satisfactorily be used to find the crystallographic angles of MnBi. A table of angles between the crystallographic planes (HK.L) and (hk.1) was calculated for MnBi from the formula0 F=are cos Hh+Kk+ 1/2(Hk+hK) + 3/4 (a/c)2Ll/v(H2 + K2 + HK + 3/4 (a/c)2L2) (h2+ k2+hk + 3/4 (a/c)2l2) on an IBM Type 650 Magnetic Drum Data Processing machine. The lattice constants used are listed in Table I and are those determined by Willis and Rooksby7 at 20°C. More recently published values obtained by both X-ray and neutron diffraction"' show no difference from these significant to the calculation. From the crystallographic angles between the basal plane (00.1) and the general plane (hk.1) in Table I, an (00.1) standard stereographic projection was made for MnBi which is shown in Fig. 1. Acknowledgments The author wishes to thank R. G. Treuting and J. N. Hobstetter for their technical assistance, and Miss D. P. Booth for programing the IBM machine for the calculations. He appreciates the opportunity to read the paper of B. W. Roberts of General Electric Co. prior to its publication. References 1H. J. Williams, R. C. Sherwood, and 0. L. Boothby: Bulletin Amer. Physical Soc., 1956 vol. 1, p. 132. 2 A. U. Seybolt, H. Hangen, B. W. Roberts, and P. Yurcisin: AIME Trans., 1956, vol. 206, p. 605: Journal oF Metals, May 1956. 3R. R. Heikes: Physical Review, 1955, vol. 99, p. 446. .B. W. Roberts: A Neutron Diffraction Study of the Structures of Manganese B.W.Roberts:ANeutronDiffractionBismuthide, Physical. Review, 1956, vol. 104, p. 607. 5 A. Taylor and S. Leber: AIME Trans., 1954, vol. 200, p. 190; JouRNal of Metals February 1954. « C. S. Barrett: Structure of Metals, 2nd Ed., p. 635. McGraw-Hill Book Co. New York and London, 1952. 7B. T. M. Willis and H. P. Rooksby: Proceedings Physical Soc., London, 1954, vol. 67B, p. 290.

Jan 1, 1958

By Paul E. Rosten

Introduction This papers describes some of the latest improvements that have been incorporated or planned by the Cleveland-Cliffs Iron Co. to reduce operating costs and improve pellet quality. The Cleveland-Cliffs Iron Co. operates and manages mining, beneficiation, and pelletizing operations in Michigan, Canada, and western Australia. This paper deals with the grate-kiln pelletizing operations at Republic, Humboldt, Tilden, Empire, and Pioneer in Michigan, and the Adams and Sherman in Ontario, Canada. Table I characterizes each operation in regard to location, ore type, pellet capacity and date that pellets were first produced. All of the operations with the exception of Pioneer and Tilden, utilize downdraft-two-pass grate cycles of drying followed by preheating. Pioneer utilizes an all-downdraft, three-pass grate cycle which consists of three drying zones followed by the preheat zone. The Pioneer and Tilden cycles have been described previously (Lindroos and Koski, 1966; Villar and Dawe, 1975; Koski, 1977). Tilden utilizes a three-pass grate cycle with a stage of updraft drying, followed by two downdraft drying stages. Recuperation systems which supply hot gases to a drying zone from second stage cooling were designed and fur¬nished for Tilden I. Tilden II will be identical. Empire IV will also be furnished with a recuperation system. The Adams grate¬kiln system was retrofitted with a recuperation system. This paper will summarize some of the efforts that are in effect or planned for grate-kiln pelletizing systems to: (1) reduce operating and maintenance costs, (2) reduce energy requirements, (3) improve product quality, and (4) meet environmental standards.

Jan 1, 1981

By Guy R. B. Elliott

If chemical mining is to work, it is extremely important to watch heat balances. Some reactions with coal give off heat and others absorb heat. The reactions of coal with oxygen or air give off heat, but the reactions of coal with steam or with carbon dioxide absorb heat. By balancing the proportions of the two types of reactions, the energy of the coal can be almost completely recovered and environmental damage is minimized. The chemical reactions are listed in Table 1 in the usual form with subscripts (s) and (g) indicating solid or gaseous materials. In reaction 1, solid corbon, C(s), reacts with gaseous oxygen, O2(g), to produce gaseous carbon dioxide, CO2 (g). H means enthalpy or available heat in the material; F is free energy, and it measures whether the reaction can go at all, and if so, how much.

Jan 9, 1973

By W. L. Zeigler

DURING the middle 1880s, shortly after the discovery of silver-lead ores in the Coeur d'Alene district of northern Idaho, it became apparent that concentration of the ores would be necessary to obtain a profitable product. Too much siliceous material was present for direct smelting, and the majority of the ores found at depth were too low in metallic content for economic smelting processes at the time. As the ores occurred in quartzite shear zones with siderite and quartz gangue, a large quantity of waste material was present in all the mines. As the galena was not finely disseminated, this made possible relatively good extraction of the argentiferous galena by coarse concentration. The first concentrators consisted mainly of coarse crushing, screening and jigging, principally by Harz jigs, the slimes being treated on buddies. Later Wilfley tables took the place of sand jigs and vanners superseded the buddies. Because of the marketing conditions, no attempt was made until 1900 to effect a recovery on the zinc minerals present, which were found associated in varying amounts with the galena. All through this period, the greater part of the production was obtained from mines containing ore assaying high in lead and low in zinc. Parts of some ore bodies would be reversed in this respect, so that ores high in zinc were left intact. During the decade after 1910, several important mines, The Success and The Interstate Callahan, containing ores high in zinc, were put into operation and were a material aid in the needed zinc production during World War I. Gravity concentration by jigs and tables was used during this period, with bulk flotation increasing in popularity for the treatment of the fine material that had already been treated by ordinary slime concentrating machinery. No extra fine grinding for flotation concentration was thought profitable at the time. TAILINGS DISCHARGED INTO STREAMS From the start of mining and milling operations in this district until 1904, no attempt was made by the various mills in the upper district to impound or stack their tailings. They discharged them directly into the adjacent creeks or streams, to be carried away by high water. The Bunker Hill and Sullivan and the Last Chance mines, both in the relatively flat valley of the district, stacked huge piles of the coarse jig tailings on the near-by river bottom. Rain and snowfall are heavy in the Coeur d'Alene district, as it is on the heavily timbered Pacific slope of the Bitter Root Mountains. A heavy runoff occurs every spring and there is an occasional flood of disastrous proportions when warm "Chinook" winds accompanied by rain

Jan 1, 1947

By P. K. Strangway, H. U. Ross

Briquets consisting of pure artificial magnetite, pure artificial hematite, and mixtures of the two were reduced by hydrogen in a loss-in-weight furnace at temperatures in the range 500° to 1000° . The rate of reduction of the pure hematite briquets increased continuously with increased temperature. In contrast, the pure nmgnetite briquets exhibited a pronounced rate ninimutn at about 700°C. Metallographic studies of partially reduced briquets rerlealed that, at this temperature, the he.matite samples reduced in a topo-chemical manner while the magnetite ones reduced uniformly throughout, and after partial reduction their cross sections contained a mixture of iron and unreacted wustite grains. No iron shells could be detected on the surfices of any of these uwstite grains. X-ray diffraction investigations indicated that these grains had a rzinimum lattice parameter when they had been formed at the rate rninimum temperature. Also, it was found that an activation energy of 41,000 cal per mole zoas required for reduction when only these wustite grains were present. Thus, it is suggested that the overall reduction rate of the rnagnetile su?nples at temperatures in the range influenced by the rate nzinirnum phenomenon was limited by the rate qf iron ion diffusion in the unreacted wustite grains. THE rate minimum phenomenon, which has often been observed when reducing iron oxides at a temperature of about 700°C, is one of the most interesting, yet unresolved, problems in the field of reduction kinetics. Basic principles of chemical kinetics and 'In some instance, a second rate minimum has been observed at about 900°C. Since most investigators are in agreement that this minimum is directly related to the transformation from a to y iron (which takes place at 911°C) and since it was not encountered during the present reduction tests, it will not be referred to in this vaver. fundamental laws of diffusion all agree that, as the temperature is increased, the rate of reduction should also increase. However, with certain ores, it has been found that their reduction rate actually decreases with an increase in temperature up to some value X where a minimum reduction rate is reached. With further temperature increases beyond X the rate becomes more rapid again. Temperature X is usually referred to as the "rate minimum temperature", while the overall type of behavior constitutes the "rate minimum phenomenon". This phenomenon has been reported by numerous investigators. They have found rate minima during the reduction of both artifiial' and natural374 magnetites and artificia15j6 and natural5" hematites. Rate minima have been observed when reducing high-purity material2 or low-grade ores,3'4 when studying particles in the micronsize range5 or relatively large agglomerates,g10 and during reduction with either hydrogen7 or carbon monoxide.11"2 Previously, this phenomenon has been attributed to many factors; these include sintering and recrystallization of the iron formed during reduction374 changes in microporosity of the ore upon redction,"" formation of dense iron shells around retained wustite grains,11716 and chem-isorption,17 to name only a few. However, most investigators who have reported a rate minimum merely speculated as to what seemed to influence it and they did not examine the fundamental causes. Consequently, the present experimental study was initiated in order to evaluate the basic factors which could be associated with this phenomenon. MATERIALS AND METHODS The experimental techniques, followed during this investigation, are similar to those which have been described previously.18 The chemically pure magnetic powder was prepared by partially reducing Fisher reagent-grade hematite with a gaseous mixture of carbon monoxide and carbon dioxide in a rotating-drum furnace. Three-quarter-inch diam cylindrical briquets which weighed about 12 g were formed from this magnetite powder and pure hematite powder. All of the briquets were sintered while they were slowly raised through the 1200°C hot zone of a vertical tube furnace. An argon stream was continually flushed through this furnace in order to prevent oxidation of the magnetite briquets, while in the case of the pure hematite briquets sintering was carried out in air. The sintered hematite briquets had a density of 5.06 g per cu cm while the density of the sintered magnetite briquets was 4.27 g per cu cm. The sintered briquets were reduced by purified hydrogen in a loss-in-weight furnace at temperatures in the range 500" to 1000°C. In all instances, the critical reducing gas velocity was exceeded and, in order to ensure that the results were reproducible, duplicate briquets of each type were reduced under each set of experimental conditions. A continuous record of the weight loss during reduction was obtained with the aid of a Statham transducer. The present experimental setup was capable of detecting a change in weight as small as 10 mg. Since a weight loss of over 2 g usually occurred during each reduction test, an accuracy of better than 0.5 pct of the total weight loss could be achieved. RESULTS AND DISCUSSION Reducibility Tests. In the first set of experiments, pure hematite and pure magnetite briquets were used.

Jan 1, 1969

By Frank Firmstone

IN April, 1873, No. 2 furnace at the Glendon Iron Works being out of blast, it was decided to alter it from an open to a closed top. The three side flues, through which a part of the gas was formerly taken off, were 15 feet below the top, and as, for various reasons, it was not convenient to cut new flues through the brickwork at the top, as is commonly done with closed-top furnaces, a modification of Coingt's charger was employed. This apparatus, as figured by De Vathaire,* consists of a cup or hopper, like that used with the cup and cone, and a central pipe for taking off the gas, which descends some distance into the furnace, and has a projection around it forming a seat for a ring of a triangular cross-section, which closes the opening between the cup and the central gas-pipe. The charge is put into the cup, and by lowering the ring, is thrown into the furnace, a part going outside of the ring toward the walls, and a part through the inside toward the gas-pipe. In this form the apparatus was not applicable, for: 1st. With a gas-pipe three feet in diameter, in a top eight feet in diameter, the openings left by lowering the ring would not be large enough to let lump coal pass through. 2d. For the charger to shut tight, the ring must bear equally against the projection made for it on the gas-pipe, and against the edge of the cup. This would not be difficult to effect when the apparatus is first put up, but a comparatively small change in the relative position of the parts, such as is almost certain to occur from expansion, would cause the ring to touch the pipe or the cup, whichever happened to be the lower, first, and leave a leak between it (the ring) and the other. In the plan adopted (Fig's. 5 and 6, Plate I), the central opening in the ring is closed by the bottom of the gas-pipe, whereby more room is left for the passage of the stock when the charger is open, than if the pipe descended into the furnace; and the pipe, instead of being rigidly supported, rests on the ring, when the charger is closed, and follows it for two or three inches as it opens, until stopped by the counter-balance lever C. When the ring is raised to close the furnace top, it comes in contact first with the bottom edge of the gas-pipe, then both are raised to¬gether, until stopped by the ring touching the edge of the cup. In this way a good joint is made at both places. * Etudes our lea Haut Fourneaux, page 108.

Jan 1, 1874

By J. H. Keeler

The tensile characteristics of Zr-Fe binary alloys containing up to 5 atomic pet Fe are reported for the temperature range —195o to 500°C. A linear relation between stress at constant strain and volume fraction ZrFe2 was found. The coincidence of data from unalloyed zirconium with zero volume fraction ZrFe2 indicated little or no solid solution in IL-zirconium, in agreement with Hayes, Roberson, and O'Brien.' The absolute increase in strength due to particle strengthening, although decreasing with increasing temperature, was a greater percentage at high temperature. ZIRCONIUM is of interest for use in nuclear reactors because of its low neutron absorption, good corrosion resistance, and high melting temperature. The alloying of zirconium with iron has been considered as a means of increasing the mechanical strength of zirconium without seriously increasing the neutron absorption " over that of unalloyed zirconium. The Zr-Fe system has a eutectic at 934°C and 23.7 atomic pet Fe and a eutectoid at 800°C and 4.0 atomic pet Fe. The zirconium-rich end of this system determined by Hayes, Roberson, and O'Brien' is shown in Fig. 1. The intermetallic phase coexisting with a and ß-zirconium has been reported as Zr2Fe3,1 with a,, - 7.04A, and as ZrFe2,2 face-centered-cubic, the phase being of the MgCu, type (C-15). It was more recently agreed to be ZrFe33 and face-centered-cubic. This intermetallic phase is essentially insoluble in a-zirconium, the hexagonal-close-packed modification; and the lack of solubility makes the system particularly interesting metallurgically. The system is strengthened almost exclusively by particles of in-termetallic phase, and there is very little solid solution strengthening to complicate the analysis. The Bureau of Mines, in its survey of zirconium-base alloys,' reported the tensile properties of Zr-Fe alloys made from chloride process zirconium, induction melted in graphite crucibles, and swaged at 850°C in iron sheaths. Additional data on these ZrFe alloys were given by Hayes, Roberson, and O'Brien.' Chubb and Muehlenkamp% have recently reported the strength of Zr-Fe alloys containing up to about 1.25 atomic pet Fe. These alloys were made from crystal bar zirconium, hot worked at 820°C, annealed at 700°C, and tested both at room temperature and at 316°C. Experimental Procedure The materials used in this investigation were high purity zirconium made by the iodide process and electrolytic iron. The composition of the zirconium as obtained by spectrographic analysis and the nominal composition of the iron are given in Table I. Alloy ingots weighing 100 g were made by are-melting under argon in water-cooled copper crucibles in a multihearth furnace."

Jan 1, 1957

By JAS. F. McCARTHY

THE present Hecla Co. is a Washington corporation; the Hecla Co. of Idaho was the old company. The older corporation owned two claims, the Hecla and the Katie May, and was incorporated for 500,000 shares of one dollar par value. The principal shareholders and officials of the older company were among the early mining men of the camp. Among the active officials were John A. Finch and A. B. Campbell. Among the directors and share- holders were Patrick Clark, J. R. Smith, Frank Upman, F. J, Kipp, Chas. Kipp, B. A. Kipp and Carl Landsee. F. J. Kipp and Carl Landsee are now directors of the Company. All of the others mentioned have died, but the surviving members of their families retain their ownership in the Company's shareholders. B. A. ,Kipp, who recently died, was the largest shareholder at the time of incorporation and Patrick Clark was the second largest shareholder. B. A. Kipp is a brother 'of F. J. Kipp, director of the Company.

Jan 1, 1924

By John F. Elliott, Robert D. Pehlke

The rate of reaction of nitrogen with liquid iron and with binary alloys of iron and Al, Cb, Cr, Ni, O, S, Si, and W were measured. The surface active elements, oxygen and sulfur, decrease the rate markedly. The other alloying elements have very little effect on the rate except when they function as deoxidizers, The rates of absorption and de-sorption were found to be equal. Several possible reaction mechanisms which may control the rate are considered. In order to describe completely the behavior of nitrogen in steelmaking processes, the mechanisms of mass transfer between the gaseous and liquid phases, nitrogen and iron, respectively, must be understood. A kinetic study to determine the nature of these mass transfer processes was undertaken, and the results of that investigation are presented in this paper. Specifically, the study was directed toward determining the influence of alloying elements on the rates at which pure nitrogen gas at constant pressure is absorbed and desorbed by liquid iron solutions: A previous paper1 reported measurements of the equilibrium solubility of nitrogen in liquid binary iron alloys. The experimental data are presented and discussed first and then several possible rate limiting mechanisms are considered. PREVIOUS RESEARCH The results of several investigations on the rate of absorption of nitrogen by liquid iron and iron alloys have been reported.2-14 There is little agreement on the rate coefficients among these studies because of the influence of geometry on the experimental system and of the purity of the liquid iron. The rate was found to be influenced by alloying content for the binary liquid iron systems: Fe-Al,2 Fe-C,4,6 Fe-Cr,4,5,8 Fe-Mn,5 Fe-Ni,5,8 Fe-O,9,10 Fe-O,9,10 and Fe-Si.2,6,7,11 Several investigators12"15 have reported that the rate of nitrogen absorption is increased in a reducing gas mixture and decreased in an oxidizing atmosphere. A mechanism for the retardation by oxygen of the absorption of nitrogen has been described by Naeser18 as the formation of an iron oxide film at the gas-metal interface. The film slows the absorption rate until it disolves in the metal, thus permitting nitrogen to enter the liquid iron. Karwat17 discussed the influence of oxygen in terms of the formation of gaseous molecules of nitrous oxide which represent a higher energy form than the nitrogen and oxygen or the oxidizing gas and consequently constitute an energy barrier for the process. Fischer and Hoffmann10 showed that the oxygen markedly reduces the rate of absorption of nitrogen, the rate constant being one order of magnitude smaller in liquid iron containing 0.15 to 0.24 pct 0 as compared to that in melts containing 0.001 to 0.02 pct 0. Although Chipman and Murphy2 reported that the rate of absorption of nitrogen in liquid iron was essentially independent of temperature, Eklund3 found that the rate increases strongly with increasing temperature as did Kootz4 and Saito.5,6 Karnaukhov and Morozov7 also reported a large temperature coefficient, but related it to increased stirring at higher power inputs in an inductively heated system. All of the authors above have treated their results assuming that the reaction is diffusion controlled, that the surface reaction is in equilibrium with nitrogen gas, and that a "first order" reaction takes place. Karnaukhov and Morozov7 and Humbert; who studied the rate of absorption in a closed system by observing pressure changes in the system as a function of time, concluded that their results best fit a diffusion-type analysis. This was further verified by von Bogdandy, Dick, and stranski18 and Fischer and Hoffmann10 who found the initial rate of

Jan 1, 1963

By Virgil Miller, F. B. Petermann, S. F. Ravitz

The Cle Elum nickeliferous iron deposit is in Kittitas County, Washington, in a rugged, mountainous region about 23 miles north of the town of Cle Elum. The Biewett Pass deposit, which is similar in character and occurrence, is in Chelan County, about 18 miles east of the Cle Elum deposit. A more or less continuous ore zone may extend between the two deposits, since iron ore is reported to have been discovered at Iron Mountain, which lies directly between them. The ore probably was formed by meta-morphism of laterite resulting from Ieach-ing of serpentine derived from peridotite. It consists largely of magnetite grains distributed through a matrix of limonitic material containing a small amount of hematite and chromite. Many of the chromite grains have shells and inclusions of magnetite. The magnetite grains range in size from 1200-mesh to 1/4-in., the average size being 48 to 65-mesh; the chromite grains range from 20 to 150-mesh. The gangue minerals are olivine and serpentine with a small, amount of chlorite, and appear both as very thin bands in the ore and 's minute fragments in the limonitic matrix. The nickel is present as minUte inclusions of a nickel silicate mineral within the magnetite and gangue par- ticles, varying in size from 1500 to about 280-mesh. Detailed analyses of 3000-lb. lots of Cle Elum and Blewett Pass ore are given in Table I. TABLE i.—Analyses of Ore Samples Per Cent Ore from Constituent cle Elum' Blewett Pass Cr....................... 2.23 2-12 Ni...................... 1.43 0.9s Fe...................... 52.9 41.4 SiOz.................... 5.6 13.4 CaO.................... 0.3 0.8 MgO................... 4-1 7-5 AI2O3................... 7.0 2.g P...................... 0.022 0.034 S....................... O.O1 o.oa Mn..................... I.I 0.4 Ba..................... nil co..................... o.oa 0.02 CU..................... 0.02 0.03 As...................... 0.03 Au..................... nil Ag°..................... O.58 Pt...................... ml Fe++.................... 8.9 5-9 Fe+++.................. 44-0 35-5 « Ounces per ton, 1 sr,cte,so,","&&$ally absent: B, W, M~, T~, V, ~i, Bi, Pb. Sb. Sn. Be, In, Hg. Zn, Zr. Cd. Preliminary Tests Attempts to beneficiate the ore by ore-dressing methods, including various 'cornbinations of sink and float, tabling, jigging, flotation, and magnetic separation, were consistently unsuccessful. A wide variety of roasting and leaching tests were made on both raw and reduced ore, but in most of the tests little or no nickel was extracted, and in none did the extraction exceed 50 Per cent. No nickel could be volatilized as the carbonyl. by treating reduced ore with carbon monoxide. Fairly good sepa-

Jan 1, 1944

By A. W. Hale

IN a work published in 1838, De Morgan, the author of the article on "Probabilities,' in the Encyclopedia Metropolitana, says " The method of least squares is not yet introduced into the affairs of common life,….that many things which are demonstrable only by the higher branches of mathematics are looked upon as useless." And he mentions an instance in which "a method was suggested for estimating the relative importance of boroughs, by considering their population and contributions to the revenue com-

Jan 1, 1881

By J. B. Newkirk, R. W. Hendricks, R. Baro

STUDIES of the kinetics of precipitation in binary alkali halide systems are of interest from a theoretical point of view, because of the possibility of controlling diffusion rates by additions of aliovalent impurities. This note reports some preliminary results of a study of the kinetics of precipitation of AgCl from supersaturated solid solutions of AgCl in NaCl containing trace amounts of divalent cation impurities. In their study of the system NaC1- AgC1, Stokes and Li1 derived the phase diagram containing a mis-cibility gap with a broad maximum at approximately 170°C. They found that single crystals quenched from above the miscibility gap and aged at various temperatures within the two-phase region gradually turned light blue, then cloudy white, and finally opaque. The rate of transformation depended markedly on the aging temperature. The light-blue color in the early stages of aging was interpreted to be the result of Rayleigh scattering from precipitated particles less than 0.1 µ in diameter. These qualitative observations have been confirmed by us. However, a more precise tool was needed in order to quantitatively follow the growth kinetics of the precipitate particles. Because of the suspected small size of the precipitate particles and for other reasons, small-angle X-ray scattering was thought to be a suitable technique for this study. Small-angle X-ray intensities scattered from powder specimens were recorded on a General Electric XRD-5 diffractometer using the four-slit geometry described by Neynaber, Brammer, and Beeman.2 The slits were 0.08 mm wide by 10.00 mm high. It was found that, with very careful alignment, meaningful data could be obtained to within 3 min from the middle of the direct beam. Chromium radiation (?Ka = 2.29Å) was used in order to spread the scattered intensity to a relatively high angle, as indicated by Eq. [1]. A specimen containing 21.0 at. pet AgCl was prepared by melting analytic reagent-grade AgCl and NaCl under a chlorine atmosphere in a vycor cap-

Jan 1, 1964

By Leonard A. Wood, A. G. Winslow

Subsidence has occurred in several areas of the upper Gulf Coast region of Texas, although in most cases this is not evident without precise instrumental leveling. As referred to in this report, the region com- prises about 7200 sq miles of the Gulf Coastal Plain and includes all or parts of the following counties: Harris, Fort Bend, Waller, Brazoria, Galveston, Liberty, Chambers, Orange, and Jefferson (Fig. 1 ). Topographic relief is low, ranging from sea level at the Gulf of Mexico to 300 ft or more in northwestern Harris County.

Jan 10, 1959

By C. E. Birchenall, H. M. Schadel

THE purpose of this study was to measure the vapor pressure of silver as the first step in the determination of activities in silver alloys and to test the limitations of the method adopted. In order to work at low pressures, below 2x10-2 mm of mercury, the orifice effusion technique was employed. To shorten the time of collection of silver from the atomic beam, radioactive silver (Ag110) was used as a tracer. The rate of effusion of a monatomic vapor from an "ideal" orifice, where the thickness of the orifice edge is negligible compared with the orifice diameter, can be readily calculated from the kinetic theory of gases, G = vM a p/v2pRT where G is the weight of material effusing from the orifice per unit time; p is the vapor pressure at oven temperature, T; R is the gas constant; M is the molecular weight of the vapor; and a is the orifice area. Consolidating constants and expressing as the weight of material effusing from the orifice in a period of time, t, (5.83)(10-2) (vM) (a) (t) (p)/vT where GT is total weight of monatomic vapor effused (g); M is molecular weight of the effusing tracer vapor; a is orifice area (cm2); t is time of effusion (sec); p is vapor pressure of effusing material (mm of Hg); and T is oven temperature (OK). The vapor effuses from the orifice in a hemispherical pattern, and the intensity of the beam in any direction is given by the cosine distribution law.' Considering this, the weight of effused material can be calculated from the amount of material passing through a circular collimator intersecting the beam. If such a collimator is in a plane parallel to the plane of the orifice and with center on the normal to the orifice center, GT = G?/1-cos2? = G?/sin2? where G? is the weight of effused material passing through the collimator, and 0 is one half the apex angle of the cone defined by the collimator circumference and the orifice center. Reducing eq 3 to the more directly measurable quantities of orifice to collimator distance, d, and collimator diameter, D, the expression becomes,

Jan 1, 1951

By W. J. Parton

THE efficient recovery and preparation of small sizes of anthracite called No. 4 Buckwheat (3/3 2 by 1/3 2 in.) and No. 5 Buckwheat (1/3 2 in. by 0), present a difficult problem to the anthracite operators. In many instances preparation of these sizes, particularly No. 5 anthracite, is extremely inefficient. In many of the older preparation plants, inadequate facilities, and often none at all, were provided as an integral part of the plant for cleaning this fine anthracite. Consequently, much of the material smaller than s, 32 in. was discarded. As the demand for these sizes increased, facilities for preparing the fine sizes were often crowded into existing structures with consequent sacrifices of capacities and efficiency. In addition to this condition, the methods of preparing the finest sizes are being developed in an attempt to improve their efficiencies. Because the demand for small sizes of anthracite still is increasing, many operators would benefit by investigating and improving the cleaning equipment employed on these sizes.

Jan 1, 1949

By T. A. Rickard

Do not write until you have something to say. Think first; then write. In order to be understood, you must know what you wish to say. Clear writing is the consequence of clear thinking. Therefore consider your subject well before you begin to write; ruminate on it; marshal the salient facts in your mind; saturate yourself with the ideas you wish to express and with cognate ideas; then express yourself deliberately. If you are bubbling over with your subject the words will come, but you might as well expect to sail without a breeze as hope to give life to words without the living thought. Here I may advert to the fact that among the uneducated it is a common expectation to acquire the knack of writing without taking the trouble to study the art of literature. I overheard a woman in a suburban train remark to her neighbor: "I'd like to be able to write well without stopping to think about it". She was one of many that would like to do a thing well without the trouble of thinking; but it cannot be done in respect of anything to which thought is essential. The possession of a good voice does not justify a person in expecting to sing successfully to a large audience; before singing in public one has to master the technique of singing; one has to learn first how to breathe properly, how to enunciate, and many other things. The successful singer is an artist, not a megaphone. Most of us would regard a man or a woman without any training in the art of singing as a fool or an impostor if he or she were to give a public concert, yet we do not recognize the equal foolishness and imposture of persons that write books before they have studied the technique of writing. That is why so many books are unreadable, and why many books by clever men are difficult to read. They start to write books before

Jan 1, 1931

By ROBERT B. COONS

SELECTIVE SERVICE must meet three important demands for man power: (1) Activities concerned with production of war goods. (2) The armed forces. (3) Civilian activities and institutions the continuance of which are essential to maintaining the structure of our American democracy. In the above enumeration of demands I have placed everything, including most of our most prized possessions and activities, after the demand for men for war production and the armed forces. To establish an order between the latter two is difficult. For the time being, at least, the Selective Service policy is to make sure that we avoid the risk of "too little and too late." No soldier, sailor, or marine should be sent from these shores to risk his life without the assurance of having a gun, clothes, food, and medical supplies. Therefore, the premium is now being placed on man power for war production and in our process of selection no stone is left unturned to see that our agencies are fully informed of the needs of war production. Our procedures set up recourses for employers of war-production man power so that their activities need not be disrupted, at least not until they have had time to train replacements.

Jan 1, 1942

By ARTHUR THACHER

PRIMITIVE man supplied his wants as they arose; as he became more civilized he anticipated them by producing more regularly and storing the products for future use. This tended to cheapen' production and prevent ' violent fluctuations and therefore tended to increase consumption. In order to anticipate our wants, we must know what these wants will be, and this can be .determined only by statistics. 'While we have made great progress in gathering statistics, they are still far from what they should be; especially metal statistics. We determine fairly, well the amount produced, but this does not answer all inquiries because of the erratic conditions of mining, it is necessary to carry larger stocks of metals than of most other articles; moreover, as metals are more or less durable, it is difficult to determine the actual consumption. We often count under consumption what is being produced and sold, while the actual consumption is what is being worn out.

Jan 1, 1921