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By R. G. Hudson, L. Yang

In electrochemical separation of metals, it is necessary to control the potential applied between the electrodes so that only the desired electrode reactions can occur. A knowledge of the minimum potential needed for a given electrode reaction to take place continuously is therefore pertinent to the success of the process. In molten chloride systems at high temperatures, activation polarization is believed to be small,1,2 so the minimum potential needed for the electrolytic decomposition of a molten metal chloride MC1n (n = valence of the metal ion) is therefore essentially the equilibrium electrode potential E of the metal-chlorine galvanic cell in the solution. If the decomposition products are pure M and chlorine at a pressure of p atm, E*Eo-rt/nf in [i] Since EO (the standard electrode potential of MCln) is a constant at a given temperature and R (the gas constant), and F (the Faraday's constant) are all constants, the variation of E with the electrolytic bath conditions is largely determined by the effect of the latter on the activity of the metal chloride amcln (standard state = pure MC1,). Measurement of E and study of how amCin varies with temperature and concentration, the nature of the solvent, and that of the coexisting solutes are therefore pertinent in the selection of optimum operating conditions for the electrochemical separation of metals. Because of its low melting point, high decomposition potentials of its components, and the low solubility of heavier metals in it, the LiC1-KC1 eutectic melt is a useful solvent and has been used in the electrodeposition of Mo,3Ce,4 and u5 metals. Senderoff and Brenner3 measured the potentials of Zn/Zn++, Fe/Fe++, Cu/Cu+, Mo/Mo+++, and Ag/Ag+ against an Ag/AgCl (pure) reference electrode at 600°C and a concentration of 4.1 mole pct of each chloride and came to the conclusion that complex ion formation occurred in some of the melts. Laitinen and LiUe gave an electromotive force series at 450°C for a number of {Metal/Metal ions (unit activity)) electrodes in LiC1-KC1 eutectic melt, the {pt/pt++ (unit activity)) electrode being chosen as the reference. Walker and Danly7 studied the ther-modynamic properties of NiC12 in LiC1-KC1 eutectic melt over a wide range of temperatures and concentrations by measuring the electrode potential between a nickel electrode and a chlorine electrode in the melt. Since potential measurements made by using the chlorine reference electrode are of more direct significance both in the study of electrochemical separation and in the evaluation of the thermodynamic properties of the melt, it is therefore decided to measure the electrode potentials of cells of the type {M/MCin (mole fraction = N) in LiC1-KC1 eutectic melt/Cl2 over a range of N values and temperature for a number of metal chlorides. The results should indicate the order by which the various metals plate out on the cathode and how this order is affected by temperature and the concentration of the metal chloride in the solu-

Jan 1, 1960

By M. C. Udy, C. H. Lorig

THROUGH the years much interest has been centered in attempting to develop a direct method of iron-ore reduction, to replace or supplement the present indirect blast-furnace process. It would not be difficult to produce a list of more than 500 patents dealing with the direct production of iron and steel, but the few of this type of process that have proved successful do not produce in competition with the blast furnace; they produce special products. A survey of the literature reveals that the equilibrium conditions for the reduction reactions (iron oxides with carbon monoxide and with hydrogen) have been fairly well established but that data on the rate of reaction are discordant, although the general effects of the variables are known. This dissertation deals with the rate of reduction of a magnetite concentrate with hydrogen. The following variables have been studied: bed depth, gas velocity, particle size and temperature. The behavior of a single particle was also studied. LITERATURE Two general factors should be considered in a study of reduction of iron oxide: (I) equilibrium relations, and (2) rate of reaction. The first factor, equilibrium, has received the attention of many investigators and the equilibria Fe304-FeO-H2-H20, Fe3O4-FeO-CO-CO2, FeO-Fe-H2-H20, FeO¬Fe-CO-C02 are fairly well established. Of the second factor, the rate of reaction, much less is known. Data are comparatively scarce and there is very little concordance. The discordance probably results from the large number of variables influencing the reactions. However, the general effect of the variables is known. Among these variables are temperature, gas velocity, particle size, porosity, gas composition (distance from equilibrium), presence of impurities, greater or less prevalence of side reactions, and even design of the apparatus itself. Wetherill and Furnas1 published an excellent paper in 1934. They point out that any one or more of five processes (the chemical reaction, diffusion of the reactant through the gas film, diffusion of the reactant through the solid phase, diffusion of the reaction product through the solid phase, or diffusion of the reaction product through the gas film) may be the slow process, and thus the rate-controlling process. It is regretted that the work of these authors was limited to experiments at one temperature, and that the range of gas compositions was limited. Langmuir2 has shown that heterogeneous reactions take place at phase boundaries.

Jan 1, 1942

By F. E. Jaumot, R. L. Smith

Self-diffusion in zinc has been used as an instrument for comparison of the absorption and sectioning techniques as a means of studying diffusion. Single crystal as well as poly-crystal samples were used asanda the temperature range of diffusion extended from 200° to 415°C. For temperatures above 200°C, the data indicate that the results obtained from the absorption technique agree with those obtained from the sectioning technique. The effect on the values of the diffusion coefficient of electroplating vs evaporation as a means of applying the tracer was investigated and no significant difference observed. It was found that an excess or deficiency of tracer did not materially affect the results obtained from the sectioning technique, but invariably caused errors with the absorption technique. NEARLY all self-diffusion experiments and many alloy diffusion experiments have employed radioisotopes as the instrument for following the diffusion. Of the various techniques in which radioisotopes are applicable, the two most widely used are the sectioning and absorption techniques. In the former, the diffusion coefficient is obtained from a curve of log concentration vs the square of the mean penetration depth. In the latter, the diffusion coefficient is calculated from a knowledge of the decrease in activity at the surface after diffusion. In spite of the importance of knowing the reliability of the diffusion data and the widespread use of these two techniques, they had not been directly compared experimentally on the same samples. Thus, such a comparison was worthwhile. The specific system chosen for this comparison was the self-diffusion of zinc, since the metal was readily obtainable in high purity, single crystals were easily grown, and the anisotropic features of the diffusion added an additional factor of interest to the comparison. Self-diffusion in both single and polycrystals was investigated, since the possibility existed that grain boundaries and grain boundary diffusion might produce different effects for the different techniques. Also, the effects of electroplating vs evaporation as a means of applying the radioactive tracer, and the effects of applying an excess or deficiency of tracer material were studied. The general experimental procedures and the mathematical analyses of both techniques have been described previously in some detail, and only those points essential to an understanding of the present work will be discussed here. The mathematical analysis of the sectioning data requires only a knowledge of the solution of Fick's equation. where C,, is the initial concentration, C is the concentration at depth x, D is the diffusion coefficient, and p is the absorption coefficient of the solvent metal for the radiation from the solute. Having obtained F from the experiment, the value of z can be read from a plot of F vs In z, and D can then be calculated if is known. The necessity of knowing the absorption coefficient causes most of the criticism of the absorption technique. It is very difficult to measure accurately under the conditions existing in the diffusion experiment, but it is absolutely necessary, as will be indicated briefly later. Portions of this problem have been discussed in detail elsewhere." The difficulties involved in the measurement of the absorption coefficient arise from three principle factors: the physical characteristics of the absorber, the geometry, and complex radiation spectra. The first two are heavily dependent upon the third. If

Jan 1, 1957

By H. I. Aaronson, H. A. Domian

ELectvon-probe analgsis has been used to in7:estigatr the partition ot alloying- elements between aus-tenite and proeutectoid ferrite (or the Jerritic component of bainite) in high-purity Fe-C-X alloys, lsuully at tzco levels of carbon content fca 0.1 and 0.4 pct in ntost steels) at temperatures between the M, and the Ae3 in Si, mn, Ni, mo, Co, Al, Cr, Cu, and PI steels. No partition ous found during the early stages of transformation at any temperature studied in the Si, ,mo. Co, Al, Cr, and Cu steels. Partition did take place, Jrowel'er, in Ihe Mn, ATi, and Pt steels, occurring in lewtperature. regions below the Ae3 of ca 130°, 65", UNDERSTANDING the mechanisms through which alloying elements influence the kinetics of austenite decomposition reactions which proceed by nucleation and 35c respectively. A break was discovered in the TTT curve for the initiation oj the proeutectoid ferrite reaction in the latter steels at the temperature at which partition began. The alloy content in ferrite at the a:y bondavy remained at constart lecels, shown experimentally to be significantly above those corresponding to eqiilib+iu??l, e'en at the longest reaction times investigated (ca 1o6sec). The partition and the TTT curve observations foere rationalized on the basis of the thermodynamic treatment developed in an accompany ing paper. and diffusional growth has been a major research objective of physical metallurgy since the latter part of the 19th century. The measurements made on the dif-fusivities of carbon and of substitutional alloying elements in austenite during the 1930's and 1940's seemed to provide a useful clue as to the nature of these mechanisms. These measurements showed that the diffu-sivity of carbon is several orders of magnitude higher than that of the alloying elements at a given tempera-

Jan 1, 1967

By G. Derge, Ling Yang, G. M. Pound

The specific conductance and its temperature dependence were measured over the entire composition range of the molten Cu2S-CuCI system. At a typical temperature of 1200°C, 10 rnol pet of the ionically conducting CuCl reduced the specific conductance from about 77 ohm-lcm-l for pure Cu2S to about 32 ohm -1cm -1, and 50 mol pet CuCl reduced the conductance to that for pure CuCI—about 5 ohm 1cm1. The nature of electrical conduction in molten Cu2S, FeS, CuCI, and mixtures was studied by measuring the current efficiency of electrolysis at about 1100°C. The Cu2S, FeS, and mattes were found to conduct exclusively by electrons, but addition of 1 5 wt pet CUS to Cu2S produces a small amount of electrolysis. Addition of CuCl to Cu2S suppresses electronic conduction, and ionic conduction reaches almost 100 pet at a CuCl concentration of about 50 mol pet. These facts are interpreted in terms of electron energy level diagrams by analogy to the situation in solids. RESULTS of electrical conductivity studies on molten Cu-FeS mattes as a function of composition and temperature have been reported.' The specific conductances ranged from about 100 ohm-' cm-' for pure Cu2S to 1500 ohm-' cm-1 for pure FeS. This is in sharp contrast with the low specific conductance of molten ionic salts for which the transfer of electricity is by migration of ions in the field. In general, these ionically conducting molten salts, such as NaC1, KC1, CuC1, etc., have a specific conductance of the order of magnitude of 5 ohm-' cm-'. It was concluded on the basis of this evidence that molten FeS and Cu,S exhibit electronic conduction. Pure molten FeS has a small negative temperature coefficient of specific conductance, resembling metallic conduction, while pure molten Cu2S has a small positive temperature coefficient, resembling semi-conduction. The molten Cu2S-FeS mattes follow a roughly additive rule of mixtures, both with respect to specific conductance and temperature coefficient. Savelsberg2 has studied the electrolysis of molten Cu2S and Cu2S + FeS. He concluded that while molten Cu2S is an electronic conductor, there is some ionic conduction in molten Cu2S + FeS3 owing to the formation of the molecular compound 2Cu2S.FeS and its dissociation into Cu1 and FeS2-1 ions. The present work does not verify his results. Chipman, Inouye, and Tomlinson" have studied the specific conductance of molten FeO and report a high specific conductance, about 200 ohm-1 cm-1 of the same order of magnitude as that found for molten mattes, and a positive temperature coefficient. They interpret these results in terms of p-type semiconduction in the ionic liquid by analogy to the situation in solid FeO.1 imnad and Derne' detected appreciable ionization in molten FeO by means of electrolytic cell efficiency measurements. In order to verify the conclusion that electrical conduction in molten Cu2S and mattes is electronic, and to gain further insight into the structure of molten sulfides, the following investigations were carried out in the present work: 1) The specific conductance, s of the molten system Cu2S-CuC1 was measured as a function of temperature over the entire composition range. As discussed later, molten CuCl is an ionic substance. It was thought that if molten Cu2S were simply ionic in nature, addition of small amounts of CuCl might not have a catastrophic effect in lowering the high conductance of the Cu2S. On the other hand, if much electronic conduction occurs, addition of the ionic CuCl should have a large effect in destroying the electronic conduction. 2) The electrolytic cell efficiency of the following molten systems was measured at about 1100°C in specially designed cells: Cu3; Cu2S + FeS, 50:50 by wt; FeS; Cu2S + CuS, 15 wt pet; Cu2S + CuC1, 5.9 to 46.4 mol pet; and CuC1. This gives a direct measure of the fraction of current carried by ions in these melts. Further, the cell efficiency, extrapolated to zero ionic current, is given by cell efficiency = (s leasile + s elexstronic). [1] s lucile for molten CulS would be expected to be no greater than that for molten CuC1, whose s lonle is about 5 ohm-' cm-1, as will be seen in the following. u,.,,.,.,.......for molten Cu,S is of the order of 100 ohm-' cm-'.' Thus, a large increase in cell efficiency from 0 to values of 10 to 100 pet upon addition of CuCl to Cu2S would indicate destruction of the electronic conductance. Conductance Measurements Experimental Procedure—The apparatus and experimental method were the same as those described in detail in connection with the study of electrical conduction in molten Cu,S-FeS mattes.' A four terminal conductivity cell and an ac poten-

Jan 1, 1957

By O.W. Ellis

Recently there has been a considerable revival of interest in the effects of the various elements commonly added to brass for the purpose of increasing its strength. For many years the work of Guillet2 alone gave reliable information in this regard. Even today his determinations of the coefficients of equivalence of the various elements relative to zinc in brass are those universally employed in industry. This is so because these coefficients have stood the test of time—their substantial correctness has been proved in almost universal practice. It is not our intention to discuss here these coefficients or their use. Rather do we wish to emphasize the need for further systernatic studies of the mechanical properties of the ternary systems of copper, zinc, and other individual elements. Since Guillet published the results of his first investigations Millington, 16 Smalley33 and Thiband 45 have added somewhat to our information. In general they have confirmed the findings of Guillet, which may be stated in the following rather general terms: 1. The addition of aluminum to the 70:30 and 60:40 brasses progressively increases their hardness and strength and reduces their ductility and resistance to shock. 2. The addition of small amounts of iron to a 60:40 brass improves its strength without affecting its ductility. 3. The addition of small amounts of manganese to a 60:40 brass causes a progressive increase in its strength and reduction in its ductility. A considerable amount of information has been amassed in regard to the effect of nickel on brass (9, 22, 41) which it is unnecessary to refer to here, in view of the scope of this paper. The situation in regard to these alloys in 1926 was very clearly stated by an anonymous writer,47 in The Metallurgist of February of that year, whose remarks were so to the point that they are well worth quoting: It will he seen that there are still large fields remaining to be studied in each of these systems (those of the aluminum, iron, nickel and manganese brasses) before our knowledge is adequate. When we come to the more complicated systems the position is even less satisfactory, and on account of the very incomplete nature of the work which has been

Jan 1, 1929

By O. W. Ellis

Recently there has been a considerable revival of interest in the effects of the various elements commonly added to brass for the purpose of increasing its strength. For many years the work of Guillet2 alone gave reliable information in this regard. Even today his determinations of the coefficients of equivalence of the various elements relative to zinc in brass are those universally employed in industry. This is so because these coefficients have stood the test of time—their substantial correctness has been proved in almost universal practice. It is not our intention to discuss here these coefficients or their use. Rather do we wish to emphasize the need for further systernatic studies of the mechanical properties of the ternary systems of copper, zinc, and other individual elements. Since Guillet published the results of his first investigations Millington, 16 Smalley33 and Thiband 45 have added somewhat to our information. In general they have confirmed the findings of Guillet, which may be stated in the following rather general terms: 1. The addition of aluminum to the 70:30 and 60:40 brasses progressively increases their hardness and strength and reduces their ductility and resistance to shock. 2. The addition of small amounts of iron to a 60:40 brass improves its strength without affecting its ductility. 3. The addition of small amounts of manganese to a 60:40 brass causes a progressive increase in its strength and reduction in its ductility. A considerable amount of information has been amassed in regard to the effect of nickel on brass (9, 22, 41) which it is unnecessary to refer to here, in view of the scope of this paper. The situation in regard to these alloys in 1926 was very clearly stated by an anonymous writer,47 in The Metallurgist of February of that year, whose remarks were so to the point that they are well worth quoting: It will he seen that there are still large fields remaining to be studied in each of these systems (those of the aluminum, iron, nickel and manganese brasses) before our knowledge is adequate. When we come to the more complicated systems the position is even less satisfactory, and on account of the very incomplete nature of the work which has been

Jan 1, 1929

By F. W. Jessen

The Mechanism of solution of salt and mixed halites of sodium and potassium is reviewed. The variation in the rate of salt removal under both laminar and turbulent flow conditions is discussed. Many changes are possible in the development of solution cavities whether used for production of salts or for storage of hydrocarbons. The parameters influencing the type and shape of cavity formed with single well or multiple well systems are examined and information presented regarding field application of techniques developed and the means of controlling overall configuration of solution cavities.

Jan 1, 1972

THE composition and quality of finished steel depend upon selection and proportioning of the raw materials of the charge as well as upon control of furnace practice. This chapter deals only with the raw materials of the basic open-hearth process that are important in determining the composition of the steel or slag. They are the metallic charge, oxygen-bearing materials, fluxes, alloying and deoxidizing additions, and certain refractory materials used for maintenance of bottoms. Other refractories, which may affect the slag composition, are discussed in Chapter 3. Wide variations are possible in the type and composition of charged materials but certain limiting relations among the elements of the charge must be observed. Since the process consists essentially of refining by the oxidation of undesired dements, a balance must be established between the sources of oxygen and the elements in the charge that are subject to oxidation (see Chapters 2 and 7). For example, if it is desired to use a high ratio of blast-furnace hot metal to scrap, it is necessary to add an oxygen-bearing material such as ore or mill scale to eliminate the excess carbon and silicon that are present in the hot metal. An example of the opposite extreme is the use of a metallic charge composed entirely of steel scrap. With this type of charge, it is common practice to substitute burnt lime for limestone as a flux and to charge some carbonaceous material such as coke to avoid an excess of oxygen in relation to the elements of the charge that are subject to oxidation. Elements such as copper and nickel, which are not oxidized or eliminated by, any other reaction, may be introduced into the charge only to the extent to which they are permissible in the finished steel. An example of adjustment of the charge for elements of this type is found in the use of steel scrap high in copper. In this case, metallic components of the charge other than the scrap should be low in copper, or a sufficiently high ratio of pig iron to scrap should be charged to dilute the copper from the

Jan 1, 1951

By M. C. Young

The Ozark Lead Company operating facilities are located in Reynolds County at the south end of the "New Lead Belt" of southeast Missouri. Development of this wholly owned subsidiary of Kennecott Copper Corporation started in May 1964, with a six foot diameter by 1250 foot deep steel lined shaft. A 20-foot diameter, 1480 foot deep, concrete lined production shaft was collared in March 1968. Production from the facilities began that month and has reached a present average of approximately 6000 tons per day. This paper describes the fully automatic system used to hoist the lead-zinc ore from a depth of 1420 feet to the surface crushing and concentrating facilities, as well as the man and materials hoisting system which allows the lowering of large equipment into the mine. MINING Galena, sphalerite and some copper minerals are found in several mineralized zones of the relatively flat lying dolomite of the "Bonneterre formation". The mineable ore zones vary from 10 feet to 110 feet thick, from 200 feet to 1200 feet wide, and several thousands of feet on strike. Two-boom diesel-hydraulic jumbos equipped with rotary percussion drills are used for both development and production. The jumbos are used principally to open the room and pillar stopes, and a track mounted down hole drill is used to bench in areas where the ore thickness warrants. Explosives used are ANFO, dynamite, and water-jell which are detonated by electric blasting caps. Broken ore (and waste) is hauled by rubber tired transports to chuted transfer raises. Approximately every 500 feet, these raises connect the orebody to the 15 foot by 28 foot train haulage level below. Two twenty ton diesel-hydraulic locomotives haul 160 tons per trip to storage pockets which have a total storage of 1500 tons of material. From these pockets the material is fed over a 6 foot by 20 foot mechanical vibrating feeder which includes one 4 foot by 6 foot grizzly section to a 48 inch by 60 inch jaw crusher. The grizzly and crusher products are transferred horizontally 45 feet on a 48 inch conveyor belt, to one of two 750 ton storage pockets. The material can flow unimpeded into one pocket or be deflected into the second pocket by a movable rock filled hopper. LOADING POCKET The material in each storage pocket is controlled by six lengths of ship anchor chain. The upper end of the 20 foot chain is anchored behind a brow in the pocket, while the lower ends are joined by a header. The lower ends of the chains are raised by two electric powered marine barge winches using 3/4 inch cables. The crusher operator controls the raising and lowering of these chains from a console in the crusher station. The upper and lower travel of the chains is controlled by cams and limit switches on the winch drive. The winches are located within 5 feet of the shaft, and shaft water continually causes problems with the electric components. A malfunction in the upper travel switch will cause the winch to pull the chains into the cable sheave (breaking the cable or sheave), while the lower switch causes the winch to unwind too much rope. Serious consideration is being given to changing the electric motors to pneumatic, since pneumatic motors will eliminate the need of any electrics at the winches. The winches can be "bottomed out" against the sheave without damage to the cable or sheave when raising the chains, and can be allowed to "free wheel" to lower the chains. A surge pocket below the two storage pockets feeds material to two

Jan 1, 1975

By T. L. Fritzlen

EXTRUSION of aluminum alloys in this country is performed mainly by direct extrusion, therefore this paper is confined only to factors affecting the rate of extrusion by this method. Many factors affect the rate of extrusion of aluminum alloys. It is the purpose of this paper to present a discussion on the factors that are subject to technical control. Most of them are closely related, so that a clear-cut distinction between them is rather difficult. However, an attempt will be made to evaluate the effect of each factor separately, as far as possible. The most important factors only will be considered, and these will be discussed in detail under three general headings: (I) characteristics of the equipment, (2) size and structure of the ingot, and (3) temperature of ingot, cylinder, and other parts. It is a well established fact' that the pressure and the speed of extrusion are related and are exponential functions of one another. Therefore, whenever a certain condition tends, for instance, to increase the pressure required for extrusion, it will reduce the extrusion speed if the pressure is maintained constant. For this reason, in this paper the effect of various conditions is expressed either in regard to their effect on the pressure required or the extrusion speed. Another established fact is the relationship between the temperature of the material being extruded and the pressure required to extrude. According to Schishokin,2 this relationship is of the exponential type, and as the temperature is increased the pressure required is decreased. It would seem from the preceding that the greatest rates of extrusion can be obtained by the use of higher temperatures. However, as is well known, other factors intervene to limit the rate of extrusion of aluminum alloys when increasing the temperature. These factors will be discussed in detail later. CHARACTERISTICS OF THE EQUIPMENT The capacity of the press determines the maximum unitary pressure that can be applied for any given cylinder diameter. Pressures used for extrusion of aluminum alloys range from approximately 50,000 lb. per sq. in. to 150,000 lb. per sq. in., dependent upon the alloy and the size of the shape extruded. Higher pressures could be used to advantage, but existing steels limit pressures employed in the production of extrusions. Numerous mechanical characteristics of the extrusion press affect extrusion rate. The most important characteristics of the press itself are: (I) sensitivity of the main pressure valve and accuracy of pressure gauges, (2) accuracy of equipment to heat the cylinder uniformly and to control cylinder temperature, and (3) accuracy of means of measuring the speed of extrusion. The variables subject to control during the extrusion operation are pressure, temperature, and speed, and it is evident that the preceding characteristics

Jan 1, 1945

By Charles M. Rolker

The main tin-producing regions of the world are known to be England, Australia and the Dutch East Indian possessions, chiefly Banca and Billiton. During recent years, the tin of the Malay Peninsula, exported from Penang and Singapore, has been coming prominently to the front. France, Austria, Hungary, Germany, Spain, South America, Russia and China still present insignificant figures. The conspicuous part which the Dutch possessions in the Indian Archipelago have taken in supplying the world with tin, is well known. Tin was discovered in Banca as early as 1710, and has been produced there ever since; but the supply has been most important since Banca came fully into the possession of Holland, in 1821. In Billiton and the adjoining island of Singkep, the existence of tin was known prior to 1822.* The Lingganese knew of its existence in the valley of Embalong, from creeks and streams in the neighborhood of Tima and Simper hills, on Billiton and also on Singkep island, but the prevailing superstition that tin-mining brought misfortune, influenced them to let this industry lie idle. The attempts of the Dutch government to test this question were lukewarm, perhaps by reason of the fear of reducing, through new discoveries, the price of Banca tin, and the island was abandoned in 1826, leaving only a military post. In 1850, Dr. Crookewit, a chemist and naturalist, was sent out to verify the rumors that tin existed in Billiton. His report was unfavorable; but in 1851 Mr. C. De Groot, a mining engineer, found tin readily, and the active work on Billiton dates from that time. Less than 600 tons were produced during the first ten years, and 3000 tons in the next decade. Billiton tin-mining is done by

Jan 1, 1892

By D. Webster

It has been found that cold work and annealing treatments greatly retard subsequent grain growth and re-crystallization in thoria-dispersed nickel and NiCr. It is suggested that this is due to cavities which form at the particle-matrix interface durilzg cold work. Some of' the cavities formed are stable at elevated temperatures and prevent the mouement of large-angle grain boundaries. The movement of these boundaries at elevated temperatures is known to start recrystal-lization and when they are pinned by voids recrystal-lization is made more difficult. TD Nichro,me had a maximun resistance to recrystallization when the initial structure was coarse-grained and had a low dislocation density. A precipitation reaction occurred between 700° and 1200° F in cold-worked TD Nichrome. It has been shown by Grant and his coworkers1-3 that a large part of the strength of dispersion-hardened materials is a result of the cold-worked structure produced during fabrication. In a comparison of the strength of cold-worked copper with and without an oxide dispersion, Grant4 has demonstrated that there is little difference in strength at room temperature. The function of the dispersion is essentially to maintain the cold-worked structure at higher temperatures than is possible in the base material. The dispersion accomplishes this by making recrystallization more difficult. The mechanism by which this is achieved is discussed in this paper. The fabrication history of the material has been found to greatly influence recrystallization behavior and this aspect is discussed in some detail. I) MATERIAL Three different thoria-dispersed materials were examined. 1) DuPont 2 pet thoria-dispersed nickel (TDNi) in 0.050-in. seeet. Thoria particle size is in the range 100 to 2500A. 2) DuPont 2 pct thoria-dispersed nichrome (20 pet Cr, 80 pct Ni) (TDNiC) in 0.125-, 0.060-, and 0.040-in. sheet. In the as-received condition these sheets have

Jan 1, 1969

By H. M. Day

THE constitution of the system silver-mercury has attracted the attention of many investigators during the last two decades, but since their results are for the most part in poor agreement, there is little need for a review of their individual contributions. It remained for the very careful thermal and microscopic investigation of Murphy1 in 1931 to give the constitutional diagram in its present and unquestioned form, which is shown in Fig. 1. He devised methods for taking cooling curves on alloys under high pressures and for the microscopic observation of alloys which contained liquid mercury as a structural constituent at ordinary temperatures. The compositions of the intermediate phases were con-firmed and supplemented through X-ray analyses by Preston and Stenbeck.3 According to Murphy, at 276° C. silver is able to dissolve 44 to 45 weight per cent of mercury, which may increase at lower tempera-tures to about 50 per cent. Preston concluded that the saturation boundary occurred at 46 ± 2 per cent at 100° C. From the values reported in the literature, these are the only ones that may be accepted as lying even in the right region.

Jan 1, 1938

By Bruce E. Grant, Thomas Jancic, Lawrence G. Dykers, Frank Buchella

Principal factors influencing equipment selection can be grouped into five basic categories: tonnage requirements, ore and waste; topography and property line considerations; ore control requirements; physical characteristics of ore and waste; and climatic considerations. Loading, transporting and ground preparation equipment are largely determined by tonnage requirements. Large size equipment is appropriate for a production of about six million tpm, medium size for three million tons and small size for one million tons or less.

Jan 12, 1973

By C. M. Loeb, T. E. Norman

The use of ball, rod and tube mills for grinding ore, cement and other materials has grown so rapidly during the past forty years that the world's annual consumption of ferrous grinding media for these mills is now estimated to be between one half million and one million tons per year. Ferrous grinding balls constitute the major portion of this tonnage. Obviously they represent suficient value to justify thorough studies of the factors governing their performance. The selection of grinding balls is governed principally by: I. Quality (wear resistance, impact resistance, soundness, and the like). 2. Sources of supply and delivered cost. 3. Grinding characteristics or efficiency in the ball mill. This paper deals principally with the quality of ferrous grinding balls. In the study of these factors certain data relative to the fundamental nature of ball wear in ball mills have been obtained. These data are also presented and discussed briefly. The Development of a Suitable Wear Test A study of the fundamental factors governing the quality of grinding balls has been hampered seriously by the fact that a competent test has, in the past, involvetd the purchase of several hundred tons of halls of a specific type which were then run in one or more ball mills for a period ranging from several months' to several years' duration. Often, during the period of test, it became necessary to change operating conditions or the character of the ore fed to the test mill with the result that the rate of ball consumption changed and the test figures became of little value. Under such circumstances, progress in the development of better grinding balls, has been necessarily slow. Economic factors and variations in the quality of balls produced by different sources of supply generally make it necessary for each mill operator to determine for himself the most suitable type of balls for his mills. In our own ball mill grinding operations at Climax, Colo., we were faced with this problem. After we had run a few large scale wear tests at considerable expense we decided to investigate the possibilities of a small scale wear test which would be capable of testing numerous types of balls within a relatively short time. The most important requirement of any test is, of course, that it give results which can be used to predict accurately the wear in full scale operations. It was known that Ellis and his associates1'2 had developed a method of testing grinding balls by small scale tests run at the Ontario Research Foundation. Ellis' method of testing was used as a starting point in our investigations. In the course of our tests a number of modifications of the original method were found to be desirable so that, by an evolutionary procedure, a method of small scale

Jan 1, 1949

By C. M. Loeb, T. E. Norman

The use of ball, rod and tube mills for grinding ore, cement and other materials has grown so rapidly during the past forty years that the world's annual consumption of ferrous grinding media for these mills is now estimated to be between one half million and one million tons per year. Ferrous grinding balls constitute the major portion of this tonnage. Obviously they represent suficient value to justify thorough studies of the factors governing their performance. The selection of grinding balls is governed principally by: I. Quality (wear resistance, impact resistance, soundness, and the like). 2. Sources of supply and delivered cost. 3. Grinding characteristics or efficiency in the ball mill. This paper deals principally with the quality of ferrous grinding balls. In the study of these factors certain data relative to the fundamental nature of ball wear in ball mills have been obtained. These data are also presented and discussed briefly. The Development of a Suitable Wear Test A study of the fundamental factors governing the quality of grinding balls has been hampered seriously by the fact that a competent test has, in the past, involvetd the purchase of several hundred tons of halls of a specific type which were then run in one or more ball mills for a period ranging from several months' to several years' duration. Often, during the period of test, it became necessary to change operating conditions or the character of the ore fed to the test mill with the result that the rate of ball consumption changed and the test figures became of little value. Under such circumstances, progress in the development of better grinding balls, has been necessarily slow. Economic factors and variations in the quality of balls produced by different sources of supply generally make it necessary for each mill operator to determine for himself the most suitable type of balls for his mills. In our own ball mill grinding operations at Climax, Colo., we were faced with this problem. After we had run a few large scale wear tests at considerable expense we decided to investigate the possibilities of a small scale wear test which would be capable of testing numerous types of balls within a relatively short time. The most important requirement of any test is, of course, that it give results which can be used to predict accurately the wear in full scale operations. It was known that Ellis and his associates1'2 had developed a method of testing grinding balls by small scale tests run at the Ontario Research Foundation. Ellis' method of testing was used as a starting point in our investigations. In the course of our tests a number of modifications of the original method were found to be desirable so that, by an evolutionary procedure, a method of small scale

Jan 1, 1949

By O. G. Lellep

IN every country economic circumstances prescribe the method used to produce a commodity at lowest cost. In Pennsylvania a man's wages for working 4 hr buys a ton of coal wholesale; in Germany a laborer must work 40 hr, or ten times as long. In western Europe, therefore, conservation of fuel is of primary importance, and recent practices of burning lime and cement differ from those employed in the United States. This paper presents data collected during a trip through western Europe in 1953. Considered uneconomical, shaft kilns for burning cement disappeared in the United States two generations ago. But because required capital investment is low and operation greatly improved, shaft kilns are still used to some extent in Europe, where fuel costs are high, and are even included in designs for plants under construction. During the last 50 years shaft kilns have been maintained at the same physical size, while their output has been increased at least four times.

Jan 7, 1954

By E. A. Anderson, M. L. Fuller

The copper-zinc phase equilibrium diagram has been the subject of many investigations. Until recently, however, the boundary of the terminal solid solution of copper in zinc (eta) has not been thoroughly investigated. This paper reports determinations of the solid solubility of copper in zinc at temperatures from 100' to 400' C., the course of the liquidus and solidus for the eta solid solution and determinations of the peritectic temperature and peritectic point for the reaction between epsilon and the melt to form eta. The liquidus of the eta phase was determined by thermal analysis and the solidus by the microscopical examination of specimens quenched from temperatures above and below the solidus. The temperature of the peritectic horizontal was obtained by thermal analysis and the composition at the peritectic point was determined by extrapolation of the solid solubility boundary of the eta phase to the peritectic horizontal. The solid solubility boundary of the eta solid solution was investigated very carefully. Particular care was used to achieve equilibrium in the alloys at each temperature selected. The X-ray, electrical conductivity and microscopical methods mere used in determining the solid solubility limits. The X-ray method measures the changes in the solvent lattice with increasing solute content and in this manner locates the composition of the alloy at which no further change in the solvent lattice takes place, the limit of solid solubility. The method of electrical conductivity measures the conductivity of the alloys of a graded series of compositions, whereby the solubility limit is indicated by a discontinuity in the conductivity-composition relationship. The microscopical method distinguishes, by direct inspection, between the homogeneous solid solution alloys and those having a secondary constituent in addition to the solid solution phase, and thus indicates from the examination of a series of alloys the solid solubility limit.

Jan 1, 1934

By H. J. Wasson, E. B. Hopkins

Throughout 1928, production of oil from Venezuela steadily increased, and at the close of the year, the output was at the rate of nearly 400,000 bbl. a day. The total for the year was approximately 106,500,000 bbl., representing an increase of about 66 per cent. over the 63,000,000 bbl. produced in 1927. Venezuela now stands next to the United States as the second largest oil-producing country in the world; and there is abundant evidence to suggest that this relationship will endure for a number of years. Reserves were notably increased in the Lake shore fields, and the potential output of the Maracaibo Basin is much greater than the current production. In spite of this, the percentage of production increase was comparatively moderate, and the rate of this increase continued to fall off slightly, as has been the case for the last three years. This does not suggest that further annual increases in Venezuelan output will not materialize; only that the rate of these increases appears to be on the decline, and that with every succeeding year the future tendency will be in the direction of a stabilized level of output. The following table shows the production trend of the country since 1925: 1925 increase over 1924, 132 per cent. 1926 increase over 1925, 80 per cent. 1927 increase over 1926, 75 per cent. 1928 increase over 1927, 66 per cent. Many factors will work to prevent a reversal of this trend, but the principal ones are strong ownership in large-acreage units, and the probable indisposition of the world market to absorb a more rapidly increasing Venezuelan output at prices profitable to the producers. The distress oil element is not a factor in Venezuela; also, any unforeseen jump, such as results in the United States from the discovery of a Seminole or a deep sand at Long Beach, or Santa Fe Springs, is impossible in Venezuela, on account of lack of means for transporting a sudden surplus of oil, and the slowness with which additional transportation equipment in the form of shallow-draft tankers can be obtained.

Jan 1, 1929