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By G. E. Pellissier, C. W. Mason

Tin has long been cited as offering a classic example of polymorphism, second in repute only to the allotropy of sulphul.. The notorious "tin disease," which Cohenl has studied so exhaustively in terms of the enantiotropic transformation of tetragonal white P tin to cubic gray a tin, has apparently encouraged the expectation that one or more additional polymorphic modifications might exist. The search for confirnmntion of this idea has, as might be anticipated, led to the accumulation of a body of miscellaneous evidence, much of which would probably never have been sought, or taken seriously even by its discoverers, but fur previous assumptions. The ball apparently was started rolling iii 1880 by Trechmann,2 who reported a new modification of tin (7 tin), which was brittle and found in "hard head," a highly arsenical, slaggy material produced in a certain stage of tin smelting. A mixture of two kinds of crystals was obtained from a Cornish tin furnace, and those thought to be 7 tin were studied crystallographically. The results indicated that these crystals were rhombic and of different density from the tetragonal tin prepared electrolytically by Miller. Their analysis was given as 98.7 per cent Sn, 1.3 per cent Fe, and traces of As, Sb, Bi and S. In 1881 von Foullon4 obtained similar crystals from a Bohemian tin furnace. Headden5 examined crystals similar to those of Trechmann and von Foullon and reported them to be monoclinic, but of analysis corresponding to stannous sulphide. Later, Stevanovic,~ by goniometric measurements, proved that these crystals of SnS were really rhombic. Groth7 pictures and describes both "rhombic tin" (Fig. 9, vol. 1) ant1 stannous sulphide (Fig. 84, vol. 1); their faces and angles correspond within the accuracy of measurement. Spencers in 1921 examined the above evidence critically; lie lound similar crystals from Cornish tin furnaces, proved them to be SnS, and even was able to analyze some of Trechmann's original specimens, finding high sulphur content. (Apparently Trechmann's analysis had been based on :L second lot of crystals, not described crystallographically.)

Jan 1, 1939

By Robert A. Bauer

This study showed that diametral point-load testing performed parallel to the bedding planes of highly anisotropic sedimentary rocks produced inconsistent results that cannot be used to accurately estimate uniaxial compressive strength. Axial point-load values from tests performed normal to bedding planes and evaluated by the T500 index produce good correlations with the uniaxial compressive strength values obtained for five different rock types. A strong correlation also existed between the moisture content and the uniaxial compressive strength of the tested lithologies. A combination of axial point-load and moisture content indices produces the best correlation with the uniaxial compressive strength test results.

Jan 1, 1984

By M. B. Bever, A. K. Jena

Equations for the heat effects of additions of mixtures of multicomponent phases to a solution have been derived in terms of the enthalpy interaction coefficients. By these equations and the measured composition dependence of the heat effects on addition of mixtures of Ag-Cd solid solutions and elemental gold to liquid tin-rich solutions, values of the enthalpy in-teraction coefficients in tin-rich solutions at 541°K have been obtained. Analysis of these results in terms of the regular solution theory and the quasichemical theory suggests that near the melting point of the solvent association in the solution becomes important. SEVERAL recent papers have discussed the nature of dilute solutions on the basis of measured enthalpy interaction coefficients. l-3 These coefficients contribute to the understanding of the constitution of solutions and can be used for the evaluation of thermo-dynamic data of multicomponent systems. Their experimental determination, however, is laborious. This communication reports values of the enthalpy interaction coefficients of silver, cadmium, and gold in liquid tin-rich solutions obtained from the measured heat effects of additions of mixtures of Ag-Cd solid solutions and elemental gold to liquid tin-rich solutions. These measurements were made in the course of the determination of the heats of formation of Ag-Cd solid solutions reported in a concurrent publication.4 THE HEAT EFFECT OF AN ADDITION TO A SOLVENT This analysis is concerned with the addition of a mixture of multicomponent phases from the temperature To to a solvent of known composition at temperature T. If Nmixture << Nsolvent, where N designates the gram-atoms involved, the heat effect per g-atom of mixture added can be expressed as (HT - HT )i = difference in heat contents of component element i in the mixture at T and To Q = heat effect on solution of the mixture at temperature T Also1 Q = S Xi [2] where ?Hi ,T,x = relative partial enthalpy per g-atom of i in solution at temperature T and composition of the solution x x = average of the atom fractions of the added material in solution before and after the addition The relative partial enthalpy ?Hi per g-atom of an element i in a dilute solution composed of a solvent 1 and the solutes j = 2, ... m is related to the interaction coefficients by the following equation5 ?Hi - ?Hi-?Hi,x1-1 + S n1ixj+ . . . +S...S...S nrixn2... Xnji...Xnmm+... [3] vhere Xj = atom fraction of solute j in the solution nri = the rth order enthalpy interaction coefficients, which can also be represented by the more general designation5 L(i)n2,n3...nm and nj may have any positive integral value or zero. For identification of various rth order interaction coefficients, nri is written as nn2i2,...nij,...nmm. Eqs. [1], [2], and [3] combine to give the following general equation for the heat effect on addition of a small quantity of a mixture to a large quantity of a dilute solution n = _?ga ?Ha,To + ? Xi(HT - HT o)i a. i + ?xi?Hi,X,i?1 + ??xnjixj + . . . + ???. . .?. . .?xinrix2n2. . . xnji. . . xnmm+ . . . [4] The first term on the right-hand side of this equation is the heat of decomposition at the addition temperature of the phases present in the mixture, the second term is the heat required to raise the temperature of

Jan 1, 1970

By R. K. Datta

Eluropium -activated yttrium vanadate, excited by short- and long-wavelength ultraviolet radiations, shows enzission lines near 6100A, the principal ones correspondirzg to transitions of EU+3 ions from 5Do to the F2 energy level. The ~neclmlallistns of absorption and etnissiorz of this phosphor have been empirically studied. The absorption is caused by two separate processes in the matrix. The phosphor YVO4:Eu and tlie matrix YVO, haue essentially the same resectance spectra in the region 2500 to 4000if. There are two broat ah~o?~ption bands: natnely, around 2600 and 3600A regions. Whet? compared with the reflectance spectra of the constituent oxides, namely, Y2O3, V205, Eu2 03, the absorption bands of the tnatvix and the phosphor in the short- and long-wavelength ultraviolet regions can be interpreted as due to charge-transfer processes involving i) Y-O and ii) 17-0, respecti~~ely. The excitation spectrum&apos; of the phosphor has two broad bands with peaks at about 2600 and 3600A regions. U can be postulated that enevgy absorbed under short- crud long-wavelength ultraziolet excitatzon, respectzcely, by Y-0 and V-O parts of the niatrix is transferred by radcatio~zless process to EU+3 ions. Thzs postulate can empirically be proved on the basis of the spectra of the systems (YVO4,-YPO4,):Eu. PO? ~ons do not have&apos; any appreciable absorption in the short or long uv regions. When P0&apos;t3 ions are substitlited for v0i3 ions in YVO,:Eu phosphors, the absorption and excitation in the lo~zg uv region are gradually reduced. Ailoreover, the £«+3 emission under 3650A excitation is decreased zuitlz increase in PO^ content, lt~lzereas the emission under 253711 excitation remains esserztially constant with as IILUCIL as 60 mole pct of YPO, in YVO,:En. EUROPIUM-activated yttrium vanadate (YV04:Eu) is a well-known phosptor.&apos;-3 When excited by cathode rays, 2537, or 3650A radiations, YV04:Eu emits typical narrow-band spectrum of EU&apos;3 fluorescence in the region of 5900 to 7100A, a very strong maximum occurring at about 6190A. This emission is considered to be due to 5Do — 7F2 transition of excite: EU*3 in 4f state. Moreover, the emission under 3650A excitation increases with temperature markedly. Because of these properties, YV04:Eu phosphor finds wide application in industries, namely, in color television tube, laser, and high-pressure mercury-vapor lamps. It is the purpose of this paper 1) to present the empirical study of the mechanism of absorption and excitation of YV04:Eu phosphor by ultraviolet radiation, and 2) to offer an explanation for the process of emission. It should be mentioned that a theoretical discussion on the mechanism of absorption in terms of the crystal or ligand field theory is beyond the scope of this paper. Empirical studies presented here are based primarily on spectroscopic and crystal-chemical investigations. EXPERIMENTAL i) Preparation of Materials. The synthesis of vanadate phosphorinvolves preparation of (Yi-.tEuj^Oj, blending the mixed oxide with an oxidic compound of vanadium, such as V205 or NH4V03, and firing the mixture at about 1000°C for several hours when YVO4:Eu forms as a primary phase. (Y1-xEux)203 compositions are prepared by coprecipitation of oxalates, and igniting them at about 1000°C. The vanadium compound is added in excess of the stoichiometric proportion for fluxing purposes. The charge is cooled, ground, and the excess of vanadium is removed by a hot wash (-80°C) of alkali or ammonia. Y(VP)04:Eu samples are prepared by mixing (Yi-xEux)203 with stoichio-metric proportions of (NH4)2HP04 and the vanadium compound. The mixtures are prefired at 700" to 800°C for 1 or 2 hr, then ground and refired at 1150°C. The firings of the phosphors are done in silica crucibles, and the homogeneity of the final products checked by X-ray diffraction analysis. ii) Spectroscopic Measurements. Diffuse reflectance sqectra of the samples within the range 2500 to 7000A are obtained by using CaF2 as standard in Cary Recording Spectrophotometer, Model No. 14. The emission spectra from phosphor plaques, excited under different ultraviolet sources, are obtained by a direct-recording spectroradiometer4 adapted with a grating monochromator with nearly constant dispersion. Maximym sensitivity in the spectral region from 2500 to 7000A is obtained with a quartz-windowed, S-20 response p$otomultiplier. The total&apos; band pass is kept about 30A. The spectra are calibrated against the light from a standard tungsten filament lamp reflected from a magnesium-oxide plaque. Brightness data given throughout this report $re measured from the height of the main peak (6190A) of the emission spectra. The excitation spectra are measured using sodium salicy-late as standard. RESULTS AND DISCUSSION The diffuse reflectance spectra of both pure and activated YV04, along with their constituent components, are shown in Fig. 1. YVO4 shows two broad absorption bands, namely, around 2500 and 3600A, respectively. Since there is little difference between the reflectance spectraoof YVO4 and YVO,:Eu in the uv region (2500 to 4000A), it can be postulated that excitation of the phosphor is mainly due to absorption by the matrix, i.e., YVO4. The question, now, is whether the matrix (Yv04) is excited as a whole, or different components are responsible for the two absorption bands. The characteristic absorption spectra of molecular ions involving transition metal ions, both in aqueous solutions and in crystals, are due to electronic transi-

Jan 1, 1968

By W. M. Parris, P. D. Frost, H. A. Robinson

The effects of hydrogen content and strain rate on the static tensile and notch-rupture properties of the Ti-3Mn-complex alloy heat-treated to differed strength levels were investigated. The extent of embriulement was found to be proportional to the amount of hydrogen present and the strength to which the specimens were heat-treated. The research suggests the possible necessity of specifying lower hydrogen limits than are now allowed when titanium alloys are heat-treated to higher strengths than are presently used. The research also supports a hypothesis advanced earlier for a mechanism of hydrogen embrittlement. MUCH attention has been focused on the effects of hydrogen in in Most of the published in- formation has dealt with the effects of hydrogen on alloys in the annealed or lowest-strength condition. The work of Kotfila and Erbin3 is one of the few exceptions. In view of the fact that heat-treatments are now being used to produce high strength in titanium alloys,&apos; it is necessary that more attention be given to the effects of hydrogen on these alloys in the heat-treated condition. Research was initiated to establish the effects of hydrogen on the properties of the Ti-3Mn-complex alloy at various strength levels. This research, which supplemented that of Kotfila and Erbin, was started because it was found that high-strength tensile specimens of this alloy were strain-rate sensitive. The essential results of the research are summarized in this paper. MATERIALS AND EXPERIMENTAL PROCEDURES Material for this investigation was a 41/2-in.-diam bar forged from a single commercial heat of the Ti-3Mn-complex alloy having the composition given in Table I. The as-received forging was reduced further by forging at 1750°F to 3/4-in. square bars. About one fourth of this material was vacuum annealed at 1400°F for 24 hr to obtain a base hydrogen content of 25 ppm. The remaining bars were hydrogenated to levels of 90, 140, and 260 ppm in a large Sievert&apos;s apparatus in the following manner: Four 3/4-in. square bars, 5 in. long, were placed in the reaction chambzr. The chamber was evacuated, heated to 1400°F, and a measured amount of hydrogen was introduced. When absorbtion was complete, as indicated by the drop in pressure, the reaction tube was cooled and the bars removed. Each batch of bars was then sealed in individual evacuated Vycor containers and heated for 24 hr at 1400°F in order to distribute the hydrogen homogeneously. After vacuum-annealing or hydroge nation, the bars were rolled at a temperature (1400°F) below the ß-transus to 1/2 - in. - diam rounds. Groups of the rolled specimens representing each of the hydrogen levels were given the following heat-treatments: 1) One hr at 1300°F, water-quenched. 2) One hr at 1300°F, water-quenched, and aged 8 hr at 1100°F. 3) One hr at 1300°F, water-quenched, and aged 4 hr at 1000°F. 4) One hr at 1300°F, water-quenched, and aged 48hr at 800°F. Heat-treated bars were machined into standard 0.250-in.-diam tensile specimens having 1-in. gage lengths. Throughout the processing and testing of this material, hydrogen analyses were made by vacuum-fusion methods to check for accuracy of hydrogen additions, homogeneity, and possible losses during processing. A summary of these analyses is given in Table II It may be seen that the actual hydrogen contents were reasonably close to the desired levels. In addition, it was noted that the variation in hydrogen content within any one bar did not exceed

Jan 1, 1959

By M. S. Seltzer

High temperature steady-state creep rates have been determined jor lead sulfide single crystals whose defect concentrations were fixed by equilibration under controlled sulfur pressure. The activation energy of creep, Qc , for undoped lead sulfide, is a function 01 composilion, decreasing from 2.9 to 2.2 ev as the carrier concentration increases from 9 x 1016 to 8 1018 electrons cm-3 for lead excess crystals, and increasing from 1.7 to 2.3 ev as the concentration of holes increases from 4 x 1017 to 1 x 1018 cm-3 in sulfur excess material. For five different composilions, Qc for undoped and bismuth-doped crystals has been found to be equal to Qpb + Qs, the self-diffusion activation energies for lead and sulfur in PbS. It is well-established1 that high-temperature steady-state creep of pure metals is a diffusion-controlled process, where the activation energy of creep is equal, within experimental error, to the activation energy of self-diffusion. The relationship between the activation energy for steady-state creep and those for self-diffusion in binary compounds is more complicated, however, because two different diffusing species must be considered, and becayse the activation energies may be influenced by compositional variations and by foreign atom additions.2-4 In some cases experimentally determined creep activation energies are correlated with those for self-diffusion of the slower-moving species, but such agreement is by no means universal. Interpretation of experimental results is difficult because few investigations include measurements of creep rates and self-diffusion coefficients of both diffusing species on single crystals of similar composition and foreign atom concentration. The objective of this investigation, therefore, is to determine the influence of stoichiometric defects and foreign atoms on steady-state creep and self-diffusion for a well-characterized binary compound. Lead sulfide, a compound semiconductor which crystallizes in the NaC1-type structure, and whose homogeneity range includes compositions on either side of the 1:l atom ratio, was chosen for study in this investigation. The pressure-temperature-composition relations for PbS are available,5,3 and deviations from stoichiometry may be monitored by electrical measurements.7 Single-crystal specimens are available to allow observation of effects due to bulk phenomena without interference from grain-boundary effects. These crystals have been employed to determine steady-state creep rates under compressive stress for "pure" and bismuth-doped PbS as a function of sulfur pressure and temperature as well as crystal orientation and applied stress in order to establish the relationships between defect concentrations and creep rates. EXPERIMENTAL PROCEDURES Crystal Growth. Lead sulfide crystals, prepared by the Bridgman method, are grown in evacuated quartz crucibles, filled with almost equal atomic proportions of high-purity (99.999 pct) lead and sulfur, and heated to a temperature above the melting point of PbS (about 1127°C) so that the lead and sulfur react to form molten PbS. The crucible and melt are dropped through the hot zone of the crystal-growing furnace at the rate of 1 cm per hr. The maximum melting point of PbS is slightly on the lead-rich side of the 50:50 composition; hence crystals grown from a near stoichiometric melt are usually n-type semiconductors containing excess lead atoms. Typically the lead excess concentration in solid solution with the PbS is 3 x 1018 atoms cm-3. Crystals containing either 1/20 or 1/2 mole pct Bi2S3 were prepared by addition of the foreign atoms prior to crystal synthesis. Preparation of Specimens of Controlled Stoichiom-etry. Since it is difficult to grow crystals of desired composition, the process of crystal growth and control of stoichiometry are separated into two distinct operations. Equilibration of as-grown PbS to a desired composition is most easily accomplished by first annealing the n-type crystals under high sulfur pressure (about 1 atm) at temperatures above 700°C. This process serves to put excess lead precipitates into solution, yielding 0 -type crystals upon quenching to room temperature. Inter diffusion occurs readily in crystals so treated, and the methods described by Bloem may then be employed to obtain crystals of controlled stoi-chiometry. For the creep measurements made in this study, this involves heating crystals in mixtures of H2 and H2S The equilibrium constant for H2S is given by: Thus the sulfur partial pressure is obtained from knowledge of the H2/H2S ratio and Kh2S for the temperature in question. Fig. 1 shows the p-T-x diagram for PbS. It can be seen that, within the stability limits for single-phase lead sulfide, desired compositions may be obtained by equilibrating under a specified sulfur pressure and temperature. Characterization of Crystals. The principal methods for evaluating PbS crystals include measurement of electrical properties and mass-spectrographic analysis. The measured electrical parameters include Hall coefficient, conductivity type, and electrical resistivity Bloem7 has shown that there is a 1:l relation between the defect concentration and carrier concentration obtained. Hence, if the contribution to the carrier con-

Jan 1, 1968

By William H. Shockley

There was an extensive mining and industrial exploitation of Russia, about 20 years ago, by Belgian, French and British capitalists; but the results were discouraging. It is said that the Belgian and French public together lost approximately $400,000,000, chiefly in the coal and iron industry of southern Russia. This loss is largely accounted for by the fact that most of the companies were formed, as usual in " boom" times, to sell stock; and that thorough investigations were not made. I11 1906, renewed interest was taken in Russian mines, especially in those of gold and copper, and a considerable literature is growing on this subject; but as yet I have seen no account of one of the large Russian mining estates. The following notes on such property, where the conditions are so different from those in the mining regions of the United States, should be of interest: This inadequate and probably somewhat inaccurate account is made up, partly from my own notes made on the ground, in the summers of 1904 and 1905, and partly from a volume on the geology and resources of the estate issued several years ago, containing surface- and mine-maps, and from a pamphlet published in 1904, giving a general account of the condition and prospects of the property. This pamphlet includes a report made in 1899 by Arthur L. Pearse, a member of this Institute. Both these books are in Russian, and were prepared by the Bogoslovsk Mining Co., which owns and operates the property. Articles in many other languages have appeared dealing with various matters connected with the estate; but I know of no other general account of it. In numerous books and articles on the Urals and Siberia, however, localities are described in which somewhat similar conditions prevail. Recent papers by

Jan 1, 1909

By L. A. Delano

During 1916, the St. Joseph Lead Co. milled 2,505,670 tons of ore. This is a daily operating average of 7855 tons. The economic concentration of such a large tonnage necessarily requires a plant equipped with modern machinery and operated efficiently. The milling process used in producing this output has been a gradual development through the long period of years that the company has been in existence. HISTORICAL SUMMARY OF MILLING PRACTICE Ore was first mined at Bonne Terre, Mo., in 1864. The early milling practice was crude. It consisted of breaking the ore into small pieces by hand, pulverizing in a Blake crusher and a pair of Cornish rolls to approximately minus 6 mm., and jigging in the old-fashioned hand jigs. Only the coarse heavy galena was saved, the gangue being shoveled off and discarded. The output for the first year under this method was only 240 tons of pig lead. The first mill of the company was a combination of extensions and additions built from time to time as the mines developed. It was a museum of early milling machinery, such as jigs, percussion tables, buddies, dolly tubs, log washers, etc., following no definite flow sheet. The chats, or tailings, were hauled to waste dumps by mule and ox teams, as much as 500 tons per day being moved in this manner, until a railroad was built in 1880. This mill was burned in 1883, at which time the annual output had reached approximately 7300 tons of pig lead. A new mill of 500 tons capacity was designed and built by C. B. Parsons. This mill has been admirably described by H. S. Munroe.&apos; The ore was crushed in Blake crushers, Cornish rolls, through 6-mm. screens, and treated by jigs of the Parsons type, percussion tables and log washers, or trunking machines, for cleaning the galena. The middlings were recrushed in rolls and treated on Harz jigs. The mill was operated without change, except later installing Gates crushers and en-

Jan 1, 1918

By B. M. Larsen, L. S. Darken

SOME years ago we collated all laboratory data then available to us on the distribution at equilibrium of manganese and of sulphur between metal and simple slags, and used the results in setting up an equation, which proved to be in accord with determinations of the distribution ratio of manganese and of sulphur between liquid steel and open-hearth slag, over a wide range of operating conditions. We now present an outline of our calculations and inferences on these two closely related questions, which are of especial importance because of the advisability of conserving manganese wherever possible. In general, our results show that in the open-hearth furnace equilibrium between metal and slag, with respect to both manganese and sulphur, is substantially attained during the finishing period of the heat, or in about a half hour to an hour after any additions were made. This implies that the end result will be identical whether manganese is added as alloy or metal to the liquid steel or as oxide to the slag. The proportion of total manganese retained by the steel is favored: (I) by use of the minimum amount of lime, consistent with other operating limitations, required to give a lime-silica ratio of about 2.4, which usually corresponds to a minimum practical slag volume; (2) by a high concentration in the slag of MnO relative to FeO; (3) by high operating temperature. Absorption of sulphur by the slag from the liquid metal is favored: (I) by large slag volume; (2 by a high concentration of active (or "free") lime and of manganese oxide dis) solved in the slag; (3) by low concentration of silica, iron oxide, and phosphate dissolved in the slag. DISTRIBUTION OF MANGANESE BETWEEN SLAG AND METAL AT EQUILIBRIUM On the basis that the distribution of manganese between liquid steel and slag is controlled by the reaction [FeO + Mn = MnO + Fe [A]slag metal slag metal] the distribution at equilibrium, at a given temperature, is expressed by the equilibrium constant for this reaction, which is defined as [K" aMoO aFeI1 dFec) aMn] where a is the activity of the molecular species denoted by the subscript. The activity of each of the several components, although it is not known precisely, is approximately equal to the concentration of each component expressed as its mol fraction; that is, as the ratio of the number of mols of the given component to the total number of mols of all the molecular species present in the metal or slag, as the case may be. Moreover, since the activity, or concentration, of iron in the liquid metal is in fact substantially constant, the term [afe] may be combined with K" to give a new constant K&apos;. Making these changes,

Jan 1, 1942

By J. H. Nead

The experiments herein described were undertaken with a view to investigating thoroughly the influence of carbon on the tensile and impact physical properties of carbon steel. The original comprehensive plan included investigation of a series of steels with varying carbon contents over a wide range of heat treatments. These were to be studied as to their static tensile qualities, and also their resistance to shock as measured by the Charpy impact bending test. A thorough metallographic examination was likewise included in the schedule. The Charpy tests and the metallographic examination have not been completed to date, and are accordingly withheld for another report. All heat treatments, however, have been made, and the static tensile tests have been completed. A description of the procedure of the experiment and the results thus far obtained are therefore reported herein. Conclusions No attempt is made to draw general conclusions from these experiments, but the curves and the data are submitted as being of general importance and wide applicability. Composition of Materials An attempt was made to secure steels increasing in carbon by increments of 0.1 per cent. from 0.1 per cent. up to 0.8 per cent., and from that composition to 1.6 per cent. by increments of 0.2 per cent. Actually, however, steels of the composition given in Table I were procured, and as the carbon contents were arranged sufficiently well so that satisfactory curves could be drawn showing the relation between carbon content and other properties, these steels were used in the experiments.

Jan 1, 1916

By W. I. Garms, J. L. Stevens

Because of the many conflicting opinions regarding the functioning of the ball load and the characteristics of ball wear in ball-mill grinding, the following résumé of reports covering recent tests conducted at the Hayden plant of the Kennecott Copper Corporation is submitted with the view of pointing out certain salient features that should throw additional light on the subject. Mills Used Cylindrical drum mills with trunnion feed and discharge were used. The discharge trunnion was 13½ in. in diameter. Dimensions inside the lining were 6 ft. 6 in. in diameter and 9 ft. 6 in. long. The mills were Britannia-lined and nine lifter bars projected 2 in. from the lining. The mill speed was 162/3 r.p.m. Feed to the mill was 9 per cent on 10-mesh, 85 per cent on 100-mesh, 77 per cent solids. New balls measured 2 in. in diameter and the approximate weight of the ball load was 40,000 pounds. Initial Test During a test that was being conducted to determine the relative economic value of standard cast balls vs. forged steel balls in the local &apos;grinding operation, certain observations were made in regard to the functioning of the various ball sizes and the characteristics of ball wear, which warranted a supplementary test for the purpose of confirming such observations. For the initial test, the necessity for developing a graduated load of the new forged balls before the test could be started was realized, but the time required to obtain a graduated load and the functioning of the various ball sizes was not clear. No advantage could be seen for starting out with a full load of forged balls, as this initial load, at the least, would have to be completely ground out and replaced by daily additions of balls before the graduation could be complete and a normal static condition of ball sizes reached. For a considerable period prior to exhaustion of this initial charge there would be an unusual quantity of worn balls of a certain size, which would not be typical of a normal charge and could influence the characteristics and functioning of the entire load. Therefore, it was decided to start by daily addition of the forged balls to a mill that contained a normal operating load of cast balls. After 88 days of operation the mill was shut down for inspection. By that time the load consisted of a mass of forged balls functioning around a large core of the residual material of the former cast-ball load. This core of cast slugs, locally referred to as "the kidney," was well defined from the forged-ball load.

Jan 1, 1947

By W. I. Garms, J. L. Stevens

Because of the many conflicting opinions regarding the functioning of the ball load and the characteristics of ball wear in ball-mill grinding, the following résumé of reports covering recent tests conducted at the Hayden plant of the Kennecott Copper Corporation is submitted with the view of pointing out certain salient features that should throw additional light on the subject. Mills Used Cylindrical drum mills with trunnion feed and discharge were used. The discharge trunnion was 13½ in. in diameter. Dimensions inside the lining were 6 ft. 6 in. in diameter and 9 ft. 6 in. long. The mills were Britannia-lined and nine lifter bars projected 2 in. from the lining. The mill speed was 162/3 r.p.m. Feed to the mill was 9 per cent on 10-mesh, 85 per cent on 100-mesh, 77 per cent solids. New balls measured 2 in. in diameter and the approximate weight of the ball load was 40,000 pounds. Initial Test During a test that was being conducted to determine the relative economic value of standard cast balls vs. forged steel balls in the local &apos;grinding operation, certain observations were made in regard to the functioning of the various ball sizes and the characteristics of ball wear, which warranted a supplementary test for the purpose of confirming such observations. For the initial test, the necessity for developing a graduated load of the new forged balls before the test could be started was realized, but the time required to obtain a graduated load and the functioning of the various ball sizes was not clear. No advantage could be seen for starting out with a full load of forged balls, as this initial load, at the least, would have to be completely ground out and replaced by daily additions of balls before the graduation could be complete and a normal static condition of ball sizes reached. For a considerable period prior to exhaustion of this initial charge there would be an unusual quantity of worn balls of a certain size, which would not be typical of a normal charge and could influence the characteristics and functioning of the entire load. Therefore, it was decided to start by daily addition of the forged balls to a mill that contained a normal operating load of cast balls. After 88 days of operation the mill was shut down for inspection. By that time the load consisted of a mass of forged balls functioning around a large core of the residual material of the former cast-ball load. This core of cast slugs, locally referred to as "the kidney," was well defined from the forged-ball load.

Jan 1, 1947

By S. C. Jones, J. A. Davis

This paper describes displacement mechanisms of micel-lur solution slugs, displuced by a thickened water "mobility buffer", in a glass micromodel and in consolidated Berea sandstone cores. Colored motion pictures, taken through a microscope, recorded interactions on a pore-to-pore bash in the micromodel. Production and differential pressure data from consolidated cores previously waterflooded to residua1 oil saturation revealed displacement mechani.sm.s macroscopically. Oil is displaced miscibly, while interstitia1 water is displaced immiscibly by the injected micellar. solution slug. Part of this water is dispersed and carried near the lead ing edge of the .slug, and some may remain as a residual saturation. Thickened water displaces any residual water. It also emulsifies with the. slug material, thereby displacing it. The displacement sequence forms banks of oil and water with relatively constant fractional flows, saturations, and mobilities. The mobility of oil and water flowing ahead of the .slug defines .slug viscosity required for stable displacement. Equations are presented that describe. several aspecis of the displacement flow behavior: oil breakthrough, oil cut during production of the stabilized bank, breakthrough of banked water and the resulting decreased fractional flow of oil, fluid mobilities, etc. Breakthroughs, calculated from the equations, are compared with experimental data. Slugs of micellar sollution, ranging from 1 to 5 percent PV, produced unusually high oil recoveries (up to 100 percent) in previously waterflooded consolidated cores. Investigation of the effect of mobility buffer size on oil recovery indicated that recovery is reduced in 3-in. X 4-ft cores for mobility buffer sizes .smaller than 50 percent of the pore volume. Introduction A new oil recovery process,* conceived in 1962, utilizes a slug of micellar solution&apos; that has sufficient viscosity to avoid an unfavorable mobility ratio with respect to the oil and water it displaces. These micellar solutions are composed of hydrocarbons, water, and surfactants, and may contain electrolytes and co-surfactants. The micellar solution is displaced by a "mobility buffer". The mobility buffer is a bank of reduced-mobility fluid, preferably an aqueous polymer solution. The entire system is displaced by unthickened water. This paper describes some of the microscopic and macroscopic displacement mechanisms observed during laboratory development of the fluids for a potential field test. Microscopic phenomena were observed photographically in a specially constructed glass flow model and macroscopic data were taken from constant rate, tertiary displacements conducted in Berea sandstone cores. Qualitative Description of Micellar Solution Flooding This section qualitatively describes displacement mechanisms that occur when a slug of micellar solution is injected into a previously waterflooded core. The slug completely removes oil from the portion of core it contacts, and banks oil in the process. The oil saturation in this bank and the flowing WOR reach definite, fixed values that are determined by water and oil mobilities and slug characteristics. This zone of constant WOR and oil saturation will be called "stabilized oil bank" in the following discussion. When this stabilized bank reaches the outlet end of the core, the oil cut jumps from zero to a constant value equal to the fractional flow of oil. Saline water has little or no solubility in the slug. Because of this. the slug displaces in-place brine immiscibly. During slug injection, most of the brine is displaced ahead of the slug, some is carried along in the leading portion of the slug, and part of the brine may become immobile. The immobile, residual brine is later miscibly displaced by thickened water. Displacement of all the oil and only part of the water during slug injection results in a higher fractional flow of oil ahead of the slug than occurs when all the water is displaced after injection of thickened water is begun. The slug spontaneously emulsifies fresh (low-salt content) water. By emulsification, the slug can become infinitely diluted, and hence totally displaced, by thickened water. Fluid saturations in the core are shown schematically in Fig. 1. Parts A and B show conditions before and after the start of the thickened-water injection, respectively. Since thickened water displaces any residual brine by-

Jan 1, 1969

By Walter McDermott

THIS machine is an improvement on the well-known endless traveling belt used for dressing slimes in many mills ; the chief point of difference, and constituting the essential advantage of the present over the old form, is the application to the machine of a secondary agitating or shaking motion, in addition to the ordinary progressive motion of-the belt. In the machine as heretofore made, the inclined belt or apron moved slowly up against a thin stream of water and ore, depositing the concentrations carried over in a tank placed below, through which the belt travelled, of course, in a reversed position. By reference to the accompanying drawings, it will be seen that in this main principle the new modification does not differ materially; but the means by which it is carried out are essentially different. The machine consists of a substantial frame of mood, F, Figs. 41, 42, and 43, within which hang the shaking frame and rollers, B B, A, Endless apron ; B, Apron frame and rollers ; C, Driving drum ; D, pulleys; El Shaft and connecting rods; F, Wooden frame; G, Shaft of regulating Pulley ; H, Yokes. supporting the upper half of the travelling apron, A, which passes below around the driving drum, C, in the water-tank, J. On leaving the water-tank, the belt passes over the guiding and tightener pulley, G. The ends of the shaking-frame, B, are provided with iron yokes, H H, bored to admit the shafts of the end rollers, and carrying a lug, by which attachment is made to the connecting rods,

Jan 1, 1875

By Frederick G. Coqueron, Joseph E. Pogue

The purpose of this study is to present the results of a detailed survey of the financial and operating aspects of 30 oil companies comprising a major sample of the American petroleum industry. This review supplements a previous paper entitled "Capital Flow and Capital Formation in the Petroleum Industry, 1934-1941,"a and deals not only with a longer period but also gives new and more revealing analyses of the capital movements and characteristics. The data are gathered from published financial statements of the companies, especially the annual reports to stockholders and Form 10-K to the Securities and Exchange Commission, supplemented by confidential information. The 30 oil companies covered by this study are listed on the leading stock exchanges and for the purpose of analysis are grouped as follows: 9 companiesb engaged principally in crude production, 4 companiesc with production averaging in excess of refinery requirements, and 17 companiesd with refinery throughput in excess of crude production. These samples are sufficiently broad and representative to constitute norms against which individual company performances may be profitably compared. The 30 companies in 1942 produced 54 per cent of the Nation&apos;s total output of crude oil and refined 79 per cent of the country&apos;s crude run to stills. The financial data apply predominantly to the domestic oil business, although 15 of the companies have investments and operate facilities in foreign countries. The net value of these foreign holdings amounted to 724 million dollars, or 12 per cent, of the combined net assets of the 30 oil companies at December 31, 1942.

Jan 1, 1944

By Oliver C. Ralston

A definite field of usefulness has developed for the brine-leaching processes of removing lead from ores and other products, so this paper reviews the developments, both in practice and in research, that have taken place since the publication of two earlier papers on this subject.&apos; Several commercial plants are now in operation and a number of semi-commercial test plants have been operated in an effort to determine the limitations of brine leaching and to compare the results with other forms of treatment. Briefly, the brine leaching of lead depends on the fact that lead chloride and lead sulfate are soluble in saturated sodium-chloride solutions. In dilute brines, the solubility of the lead salt is less than in pure water; but in the strong brines, the solubility is greater than in pure water due, supposedly, to the formation of a double sodium-lead chloride. This is seen in Fig. 1, which shows the results of M. Demassieux2 on the solubility of lead chloride in sodium-chloride solutions of different concentrations and at three temperatures. The curves are not those given by Demassieux but are calculated from his results in order to convert them to units common in metallurgical work. The right-hand branch of each curve shows that if the solution is kept in contact with solid sodium chloride the lead chloride can be almost entirely displaced from solution, but that brines which are saturated with sodium chloride, but are not in contact with the solid salt, have a very high solubility for lead chloride. The diagram gives the analysis of the solution in grams of lead per liter, although the substance actually in solution is lead chloride. At 100" C. as much as 100 gm. of lead per liter can be obtained; but at lower tem-

Jan 1, 1924

By P. A. Fisher, J. B. Wilson, D. J. Whitehead, C. J. P. Ball, A. C. Jessup

The properties of a new magnesium alloy ZT1 containing 3.0 pct Th, 2.5 pct Zn, 0.7 pct Zr are described. The alloy possesses good creep and fatigue resistance up to 650°F, is free from microporosity, and is readily sand-cast. ZT1 is shown to be superior to zinc-free Mg-Th-Zr alloys. THE advent of the jet engine created a demand for a light sand-casting alloy capable of being cast into large complex shapes and capable of resisting creep at temperatures up to 500°F. This demand has been largely met by alloys of the magnesium-cerium mischmetal-zirconium types, containing about 3 pct Ce mischmetal and 0.7 pct Zr, typified by Elektron magnesium alloys MCZ and ZREI, the latter alloy also having a zinc addition of 2.5 pct. These alloys utilize the valuable properties at elevated temperatures conferred by the addition of rare earth metals to magnesium, a fact which has been known for many years and discussed by several investigators.1-1 Murphy and Payne8 showed that the addition of the powerful grain-refining element zirconium to Mg-Ce mischmetal alloys produced alloys with attractive room temperature properties combined with good creep properties and castability. With the increasing power of modern jet engines the temperatures to which some of the magnesium parts are subject are likely to exceed the safe working range of the cerium-mischmetal-containing alloys, and at the beginning of the research considerable interest had been shown by aeroplane engine designers in a magnesium sand-casting alloy suitable for service at higher temperatures, e.g., 600°F and above. At an early stage in the development of this type of alloy a check on the fatigue properties at elevated temperatures indicated that, since the fatigue limit even at 108 eversals was appreciably higher than any permissible creep stress, the main emphasis of the research could be concentrated on creep behavior. The primary aim in developing the new alloy has therefore been to attain maximum creep resistance; but due consideration has also been given to other important properties such as castability, tensile strength, and cost. It is by now well established that it is not possible to correlate creep strength with other short time mechanical properties such as are obtained in tensile

Jan 1, 1954

By H. S. Munroe

To those familiar with ore-dressing practice, it is hardly necessary to dwell upon the importance of the jig. Within its proper sphere no substitute has been found that does the work as well or as cheaply. Its capacity is large, it requires but little attention, and the losses are small. In one form or another, it is the principal machine used in the concentration of low-grade ores, and for the separation of one metallic mineral from another; and it is almost the only machine used for the purification of coal. The present paper is a study of the action of the jig in the light of results obtained in the Lake Superior copper mills, ad at the St. Joseph Lead Co.&apos;s dressing-works, in Missouri; and a description of experiments undertaken with the view of reproducing and isolating the conditions of jigging, in order to develop the laws which underlie the process. There are two recognized systems of jigging, the English and the Continental or German. The English system is a development of the hand-jigging formerly employed in Cornwall and other metalliferous districts of England, and introduced by English miners to this country. In this method the crushed ore, coarse and fine together, is first jigged oh a

Jan 1, 1889

By Augustus Locke

In 1900, when. the public first heard of "secondary enrichment," the Butte chalcocite seemed clearly supergene. Mining, through successive regions of leached capping, bonanza sulfide, and sulfide less rich, had paused at lean bottom levels which, though chalcocite-bearing, suggested the waning of copper. The deepest chalcocite, at 1500 ft., was yet too shallow to disturb the supergene hypothesis. But, with deeper mining, lean levels yielded to fat ones. Here and there they showed, within the same vein, an inverted distribution, chalcopyrite above and chalcocite below. To the miners&apos; astonishment, they carried chal-cocite, unaffected by cross faults, on an independent course to the depth of 2500 ft. The pattern of ore distribution, hitherto revealed only in fragments, was now appearing in perspective, and, in the depth of the chalcocite, was beginning to make Butte differ from all districts where the chalcocite is indubitably supergene. The idea of hypogene origin at length came into favor; by 1913, when Sales&apos; advocated this origin, the argument had become a powerful one. This argument rested on field evidence; but, already, there was beginning to emerge microscopic evidence not included in this argument. Especially pertinent was the proof that (1) the deep chalcocite lies in-mixed with bornite, often microscopic; (2) the deep chalcocite often replaces bornite; and (3) replacement of bornite by chalcocite is accomplished more easily than that of pyrite, enargite, or chalcopyrite. The microscopic evidence has been accumulating for ten years and it demands

Jan 1, 1924

By Edward Keller

About a dozen years ago the art of bessemerizing copper- * matte, brought to these shores from France, was first established at the smelter, in Butte, Montana, of the Parrot Silver and Copper Company, which had bought the process from Mr. Manhks, the inventor. Through the efforts of Mr. J. E. Gaylord, general manager, and Mr. A. J. Schumacher, snperintendent,, assisted by an able staff, the new method rapidly underwent, at the Parrot establishment, an evolution towards higher perfedion, and within a few years its success and its advantages were so marked that all the great works in the west followed in the footsteps of this pioneer. The converter-process has now practically superseded the reverberatory-process in this country. The latter will undoubtedly, in a not very distant future, be relegated to metallurgical history. The writer has availed himself of what was perhaps the last chance to make comparisons of the two methods, working practically on the same material on an extensive scale, the reverberatory process being that of the Baltimore Copper Smelting and Rolling Company,* while the converter-process is that of the Anaconda Copper Company—both using the matte from the latter company&apos;s works in Anaconda, Montana. For the greater portion of the material considered in this paper, the writer is indebted to the two companies. In order to understand the difference of behavior of the several elements, and the difference of the copper produced in the two processes, it is best to study and follow those elements

Jan 1, 1899