Search Documents

By R. T. Mishler

Silver-gold. mine, in northern Mexico, with arrow veins in rhyolite. One fourth area developed has been ore. Deposits average 20 in. wide and 73 oz. silver per ton; diluted in mining to 40 oz. per ton. Developed by drifts and raises at 100-ft. intervals. Samples cut every 5 ft. Ore and waste sampled separately to make combined stoping width 3 or 3 1/2 ft. Ore reserves figured to sloping width; high assays not modified. Tonnage and assay of ore extracted higher than estimates. Ore stoped principally by cut and fill method. Cars from each stope counted and sampled. Cars check tonnage to concen¬trator within 1 per cent.; silver assay 9 per cent. high. Tonnage and assay from scopes corrected to agree with feed to concentrator. Profit or loss for each slope estimated monthly. THE Lucky-Tiger mine is a silver-gold property, situated at El Tigre, in the northeastern part of Sonora, Mexico, at, an elevation of 6000 ft. in the Sierra Madre Mountains. It is 30 miles by wagon road from the Esqueda station on the Nacozari railroad. Since its discovery in 1903, the mine has produced forty million ounces of silver. The ore has averaged 40 oz. silver and 0.25 oz. gold per ton. Copper, lead and zinc have been of minor importance, having averaged 0.4 per cent., 1.1 per cent., and 1.5 per cent., respectively. The richness of the ore,, combined with its occurrence in narrow veins, required the use of the more expensive methods of mining.

Jan 2, 1925

By Samuel Lasky

THE writer has been interested in determining the mineralogic dis-tribution of silver in the base-metal ore of the Ground Hog mine of the Asarco Mining Co. in the Central mining district of New Mexico.1 This ore consists of a varitextured mixture of sphalerite, chalcopyrite, galena and pyrite in a quartz gangue. The average ore contains 14 per, cent of zinc, 9.5 per cent of lead, 5 per cent of copper, and 10 oz. of silver per ton. Generally it is accepted that the silver in ores of this type, in which no definite silver minerals can be recognized, is contained in the base-metal minerals. Published assays of pure mineral specimens from many dis-tricts show that each of the base-metal minerals contributes in some degree to the total silver content of the ores, and to determine the pro-portionate amount contributed by each mineral in any specific ore it has been the practice to assay selected specimens of each mineral, the purity of which has been determined microscopically. There being no such assays available for the Ground Hog ore, and it being impract cable to have enough of them made to give average results, the writer resorted to a mathematical attack upon composite assays of large quantities of ore and concentrates. Surprising results were obtained, and it is the threefold purpose of this paper to present these results, to describe the mathe-matical method used, and to point out the value of using this method even when assays of pure specimens are available.

Jan 1, 1934

By S.G. Bankoff

Ince1 proposed that electrostatic attraction between oppositely charged particles was responsible for slime-coating. Del Giudice2 postulated the metathetic formation of a cementing compound. Wark3 suggested that prevention of slime-coating was related to peptization of the slime. In the experiments of Table I the technique employed was essentially that of del Giudice, with the difference that the particle was examined under a film of water rather than dry.4 In general, the polished particle was agitated for 2 min. in a pulp consisting of 12.5 grams of the slime (—200 mesh) and 50 C.C. of distilled water, washed in three baths of distilled water, and examined at 220 diameters with the Leitz Ultropak. Observations of Brownian movement were made at 850 diameters with dark-field illumination. Several of these experiments do not jibe with the metathesis theory. According to published solubilities,5,6 the lead salts of the anions in experiments c through g are more insoluble than lead carbonate, there- fore should prevent the formation of lead carbonate on the galena surface. In experiment i the calcium oxalate, which precumably was on the calcite surfaces, should have permitted the formation of a lead carbonate cement by virtue of its greater solubility. Experiments j through m show that the addition of lime accelerates the deposition of quartz onto a galena surface. The writer is unable to postulate a satisfactory cementing compound, according to the metathesis theory, to explain this effect. These experiments led to the conclusion that the metathetic formation of a cement-

Jan 1, 1943

By S. G. Bankoff

INCE1 proposed that electrostatic attraction between oppositely charged particles was responsible for slime-coating. Del Giudice2 postulated the metathetic formation of a cementing compound. Wark3 suggested that prevention of slime-coating was related to peptization of the slime. [ ] In the experiments of Table I the technique employed was essentially that of del Giudice, with the difference that the particle was examined under a film of water rather than dry.4 In general, the polished particle was agitated for 2 min. in a pulp consisting of 12.5 grams of the slime (-200 mesh) and 50 c.c. of distilled water, washed in three baths of distilled water, and examined at 220 diameters with the Leitz Ultropak. Observations of Brownian movement were made at 850 diameters with dark-field illumination. Several of these experiments do not jibe with the metathesis theory. According to published solubilities,5,6 the lead salts of the anions in experiments [c] through g are more insoluble than lead carbonate, therefore should prevent the formation of lead carbonate on the galena surface. In experiment [i] the calcium oxalate, which presumably was on the calcite surfaces, should have permitted the formation of a lead carbonate cement by virtue of its greater solubility. Experiments [j] through m show that the addition of lime accelerates the deposition of quartz onto a galena surface. The writer is unable to postulate a satisfactory cementing compound, according to the metathesis theory, to explain this effect. These experiments led to the conclusion that the metathetic formation of a cement-

Jan 1, 1941

By R. J. Borg, C. E. Birchenall

The self-diffusion coefficients for a iron have been deternzined between 980° and 1167° K using Fe55 as the tracer. With decreasing temperature the diffusivity was found to decrease more rapidly than predicted by the Arrhenius equation in the region of the Curie temperature. The diffusion coefficients obtained well above the temperature of the magnetic transformation are more precise ard differ substantially from all the previously reported values. In the temperature region beginning at least 50" above T,, the diffusion coefficient is given by D = 118 (±2) exp 1 HE self-diffusion coefficients for a iron have been reported previously as the result of four independent investigations The general lack of agreement and the poor precision of most of the previous work prompted the redetermination by the present authors. The possible effect of the onset of ferromagnetism upon the diffusivity5 provided an additional impetus for this investigation. The earlier measurements of Birchenall and Mehl1 gave low values for the diffusion coefficient at temperatures below the Curie temperature, Tc. However, the precision of these measurements is not sufficient to establish an indisputable correlation between the low values and the magnetic transformation. The results of this investigation along with all the previous ones are shown in Fig. 1. EXPERIMENTAL Small rectangular samples, approximately 1 by 0.5 by 0.3 cm, of high-purity iron (Vacuum Metals Corp., "Ferrovac") are first heated in hydrogen at 900°C for24hr in order to remove possible trace amounts of dissolved carbon and oxygen. The small

Jan 1, 1961

By S. G. Bankoff

Ince1 proposed that electrostatic attraction between oppositely charged particles was responsible for slime-coating. Del Giudice2 postulated the metathetic formation of a cementing compound. Wark3 suggested that prevention of slime-coating was related to peptization of the slime. In the experiments of Table I the technique employed was essentially that of del Giudice, with the difference that the particle was examined under a film of water rather than dry.4 In general, the polished particle was agitated for 2 min. in a pulp consisting of 12.5 grams of the slime (—200 mesh) and 50 C.C. of distilled water, washed in three baths of distilled water, and examined at 220 diameters with the Leitz Ultropak. Observations of Brownian movement were made at 850 diameters with dark-field illumination. Several of these experiments do not jibe with the metathesis theory. According to published solubilities,5,6 the lead salts of the anions in experiments c through g are more insoluble than lead carbonate, there- fore should prevent the formation of lead carbonate on the galena surface. In experiment i the calcium oxalate, which precumably was on the calcite surfaces, should have permitted the formation of a lead carbonate cement by virtue of its greater solubility. Experiments j through m show that the addition of lime accelerates the deposition of quartz onto a galena surface. The writer is unable to postulate a satisfactory cementing compound, according to the metathesis theory, to explain this effect. These experiments led to the conclusion that the metathetic formation of a cement-

Jan 1, 1943

By Teder R. I., M. M. Protodyakonov

In order to find an empirical relation between a quantity F and (m) independent variables or factors, each of which take (n) different values or levels, it is necessary to conduct nm different experiments (all possible combinations of the factors), each of which has to be repeated a few times (usually five) due to the scattering of the data. The total number of such experiments is very large, thus for example, when m = 4 and n = 5, it is equal to 5.54 = 3125; and very rarely is it possible to conduct such a number of experiments. Various possible methods of planning partial experiments are illustrated in Fig. 1. Each method shows a large combinative square consisting of five columns and five rows of middle squares, each of which, in turn, is further divided into five columns and five rows of cells. Such a partition corresponds to a plan of an experiment with four factors, each of which takes five different levels. The blackened cells indicate the combination of factors in a partial experiment. The total number of experiments is reduced on the basis of the following considerations: a) The effect of only a few levels of some factors is studied (Fig. la). Such an investigation gives no information on the effect of some factors, therefore it cannot be accepted as satisfactory; b) By reducing the number of levels of each factor; in such a case it is not possible to obtain an empirical relationship, but only whether some factors have an effect. This is evidently inadequate;

Jan 1, 1971

By Fred P. Dewey

IN preparing material for the exhibit of the National Museum at the New Orleans Exposition in 1881, it was decided to attempt to photograph the interior of a coal-mine, in order to get a strictly truthful representation of a thick coal-seam, and to show incidentally the methods of mining. While we have many drawings, both mechanical and artistic, illustrating the subject, they are not satisfactory for these purposes, simply because they are drawings. Aside from this, much interest attaches to pictures of inaccessible places, and the enlarged copies (30 inches by 40 inches) of the photographs we succeeded in obtaining, have attracted a large amount of attention from the visitors to the Museum. The Kohinoor colliery, Shenandoah City, Pa., was selected as most suitable for the attempt, principally on account of the fine exposure of the Mammoth bed, and the comparatively level character of the workings, in that colliery. This is one of the many anthracite-mines of the Philadelphia and Reading Coal and Iron Company. A detailed section of the fiftyfoot or Mammoth bed in this colliery is as follows: Feet. Inches. 1 0 Clod. 1 7 0 Coal. 1 0 Slate. Top Split. 8 0 Coal. 1 6 Slate divider.* 6 0 Coal. 1 0 6 Slate. 2 6 Coal. 0 5 Slate. 1 8 Coal. 1 2 Charcoal. 5 0 coal. 1 0 Bone and Coal. „ „ Coal. [ Bottom Split. 0 6 Bone and Slate. 3 0 Coal. 0 10 Bone and coal. 1 2 Coal. 0 2 Bone. 4 4 Coal. 0 1 Bone. 0 8 Coal.

Jan 1, 1888

By Bernard York, John J. Reed

J. P. Zannaras (U.S. Tungsten Corp., Congress, Ariz.) —In the investigation described in the paper by Bernard York and John J. Reed, the 8x8x8-in. square block was subjected to compressive forces from three sides, top, side, and rear. Let us refer to the stresses set up by these forces as Sz due to top pressure, Sy due to side pressure, and Sx due to rear pressure. At the section across the 2-in. hole (when failure occurred at 317 psi) the compressive stress Sy was equal to 317 x 8/6 = —422 psi, the top compressive stress S; is of the same intensity, —422 psi, and the rear compressive stress S, equals —317 psi. The true stress is T = Sy — S — S Taking as 0.2,* Taking the case when the opening was ½ in. and failure occurred at 517 psi, 8 Sy - 517 x -----= —537 psi 7.5 8 Sz = 517 x-----= —537 psi 7.5 Sx = —517 psi The true stress T = Sy — Sz — S, T - —537 + 0.2 x 537 + 0.2 x 517 = —327 psi. It can be shown that the above fundamental formula holds good not only for the above two examples but for all sizes of openings used, because when this formula is expressed in terms of the external pressure and size of the opening it agrees perfectly with the experimental results obtained by the authors and given in Fig. 12 of their paper. General formula: T = Sy — s: — S....

Jan 1, 1955

By Frank C. Greene

The wildcatting in northern and northwestern Missouri, which started in 1939, was continued in 1940. Two new gas fields were found and one discovered in 1939 was further extended. The total number of completions was 94, of which 5 were oil wells with about 48 bbl. initial production, 30 were gas wells with an initial open-flow capacity of 37,655,000 cu. ft., and 59 were dry holes. The outstanding discovery was the Polo gas field, T. 55 N., R. 28 and 29 W., in Caldwell County. A sand now believed to be a lens in the Bandera shale at a depth of 400 ft. yielded flows of more than 12,000,-000 cu. ft. In all, I0 wells with 31,490,000 cu. ft. of gas, were drilled. The rock pres-sure is 80 lb. At present no arrangements for an outlet have been made. In Platte County, the Prairie Point gas pool in sec. 7, T. 51 N., R. 33 W., and sec. 12, T. 51 N., R. 34 W., and the Lake-side pool in sees. 5 and 6, T. 50 N., R. 33 W., were further developed, and in the latter both oil and gas have been found, but data are not available for publication at this time. Drilling for gas continued in proven areas in Clay County, and for both oil and gas in proven areas in Jackson and Cass Counties. Table 1 summarizes the results of drilling in Missouri in 1940.

Jan 1, 1941

By Frank C. Greene

The wildcatting in northern and northwestern Missouri, which started in 1939, was continued in 1940. Two new gas fields were found and one discovered in 1939 was further extended. The total number of completions was 94, of which 5 were oil wells with about 48 bbl. initial production, 30 were gas wells with an initial open-flow capacity of 37,655,000 cu. ft., and 59 were dry holes. The outstanding discovery was the Polo gas field, T. 55 N., R. 28 and 29 W., in Caldwell County. A sand now believed to be a lens in the Bandera shale at a depth of 400 ft. yielded flows of more than 12,000,-000 cu. ft. In all, I0 wells with 31,490,000 cu. ft. of gas, were drilled. The rock pres-sure is 80 lb. At present no arrangements for an outlet have been made. In Platte County, the Prairie Point gas pool in sec. 7, T. 51 N., R. 33 W., and sec. 12, T. 51 N., R. 34 W., and the Lake-side pool in sees. 5 and 6, T. 50 N., R. 33 W., were further developed, and in the latter both oil and gas have been found, but data are not available for publication at this time. Drilling for gas continued in proven areas in Clay County, and for both oil and gas in proven areas in Jackson and Cass Counties. Table 1 summarizes the results of drilling in Missouri in 1940.

Jan 1, 1941

By F. A. Hill

Coal mining in the State of Washington offers many interesting problems for the mining engineer, due to the varied physical conditions occurring in different fields, and often in, the same mine. The different coal seams worked in the same mine commonly require different mining and transportation methods for economical operation. The coal measures have inclinations ranging from 5° to vertical, and in the same mine the dip of the coal may vary from 30° to 50°. In all fields, the seams are extensively faulted, folded, and sheared. The quality of the coal produced ranges from brown lignite to bituminous- coking coal, the following being typical analyses: Lignite Sub Coking Coal bituminous Moisture 23.5 14.30 0.57 Volatile hydrocarbon 31.0 33.03 23.57 Fixed carbon 37.4 41.30 65.55 Ash 8.1 11.37 10.31 100.0. 100.00 100.00 Very little of the coal contains as much as 0.75 per cent. sulphur. The brown lignites occur mostly in Lewis and Thurston Counties, and, as a rule are very cheaply mined. This coal has been successfully used in locomotives of the Oregon & Washington Railroad, after equipping them with specially designed fireboxes. The sub-bituminous coals occur in all the coal-mining counties. Their cost of production varies widely, according to the character of the formations, the pitch, and the wall conditions. This makes a fairly good steam coal, but the lump is used mostly for domestic trade, after grading into lump, nut, and pea.

Jan 4, 1918

By B. E. Eakin, A. L. Lee

Atmospheric pressure viscosity values For light hydrocarbons were calculated by a simple mixing rule based on the Sutherland constants for pure components. This method was further extended so that the atmospheric pressure viscosity of a mixture may be calculated based on the molecular weight information only. INTRODUCTION A proven method for estimating the gas-phase viscosity of a mixture is the one by Herning and zipperer.l This mixing rule has the following form: One method for calculating the pure component viscosity i is the Sutherland equation,2 which has the following form: The Sutherland constants B and S are determined from experimental data. A set of Sutherland constants for light hydrocarbons based on the data of several investigators3-5 is presented in Table 1. APPLICATION The Herning-Zipperer equation and the Sutherland equation were used to obtain an equation for calculating the gas-phase viscosity of light hydrocarbons. This equation has the form, Eq. 3 was used successfully in the study of methane-n-butane mixtures.6 Further analysis indicated that the Sutherland constants are a function of molecular weight.7 The gas-phase viscosity may be calculated based on molecular weight information only. The following equation was developed: The atmospheric pressure viscosity of ethane, propane, n-butaneand four methane-propane mixtures calculated on the basis of Eq. 6 are compared with the data of other investigators in Tables 2, 3, 4 and 5, respectively. A plot of atmospheric pressure viscosity vs molecular weight based on Eq. 6 is presented in Fig. 1.

Jan 1, 1965

Department of Conservation and Development, State of North Carolina, Raleigh, N C H J Bryson, State Geologist. The latest list of publications will be sent upon request. Of the many Bulletins, Economic Papers, Circulars and Volumes issued by the Department of Conservation and Development, the following are available and relate to mining and geology of the state ? Bulletin 18, Bibliography of North Carolina geology, mineralogy and geography (1909), 50 cents, 21, The Gold Hill mining district (1910), 15 cents, 22, Report on Cid mining district (1911), 15 cents, cloth 75 cents, 25, Zircon, monazite and other minerals, 15 cents, cloth, 75 cents, 28, Limestones and marls, 15 cents, 29, Kaolins of North Carolina, 50 cents, 31, Deposits of brown iron ore, 50 cents, 32, Magnetic iron ores, 15 cents, 33, The Deep River coal field, 50 cents, 37, Pyrophyllite deposits, 35 cents A series of the Economic Papers review the mining industry in North Carolina for the years cited Those now available are Economic Paper 23 (1908-1909-1910), 10 cents, cloth, 50 cents, 49 (1913-1917), 20 cents, 55 (1918-1923), 25 cents, 60 (1924¬1925), 15 cents, 63 (1927-1928), 25 cents. Other available Economic Papers on geology and mining are No 3, Talc and pyrophyllite deposits (1900), 25 cents; 58, Oil prospecting well near Havelock (1927), 5 cents, 59, Oil-bearing shales of Deep River Valley (1927), 10 cents Available volumes on geology. Vol 1, Corundum and the basic magnesian rocks (1905), 35 cents, cloth, $150, 5, The Cretaceous formations of North Carolina (1923), cloth $1 75

Jan 1, 1933

By R. Van A. Norris

The following tests were made, during 1889, for the Susquehanna Coal Company, to determine the relative efficiency of several styles of mine-car wheels in use at their collieries at Nanticoke, Pa. The wheels experimented upon may be divided into two classes: The "old style" (Figs. 1 and 2), which are oiled at every trip; and the "new style" (Figs. 3, 4, and 5), which require oiling about once in two to four months. Fig. 1 shows a section of a plain cast wheel, with patent annular oil-chamber. This is held in position on the axle by a square, split cotter-pin. Fig. 2 is a similar wheel, with a patent cast bushing, which is readily replaced when worn. The lubrication is effected by a simple oil-hole, but the oil is delivered a little inside of the gaugeline of the wheel, where it is most needed. Figs. 3, 4, and 5 are sections of a " new style " patented, self-oiling wheel. In this, the outer end is cast closed, and the wheel is fastened to the axle by a spring cotter-pin passed through one of the plugged holes. Dirt is prevented from entering the open end by a cap, with faced end and packing-ring, fitting over the end of the hub. The lubricant is introduced into the oil-chamber through one of the plugged holes in the hub. When the wheel is in motion, the lubricant is thrown by centrifugal force away from the axle, enters the two ports shown, and is

Jan 1, 1890

By R. S. Sandhu, L. E. Baker, W. Y. Shieh

The finite element method of analysis was introduced by Clough.1 Within a short period, it has developed into a powerful solution technique in structural and continuum mechanics. It has been used to solve boundary value problems in two and three-dimensional elasticity.2-5 Anisotropy and heterogeneity of materials were allowed for at the earliest stages. 1,4 Its application has been extended to allow for cracks,5 creep and viscoelasticity, 6,7 incremental construction,6-8 nonlinear elasticity3,9 effect of joints in rock,10 and to materials with different behavior in tension and compression.7 Because of its versatility, the finite element method has found increasing application in the field of rock mechanics. In fact, several of the more significant developments have been motivated by problems in this field. Elasto-plastic material behavior based on the incremental or rate-type theory of plasticity rather than the deformation theory was considered by Reyes and Deere11 A material law based on a generalization 12 of the Mohr-Coulomb criterion was used. In this chapter, the formulation of material laws developed by Reyes and Deere 11 is used. An efficient analysis procedure, incorporating recent developments in finite element analysis, is developed for plane-strain conditions. To demonstrate its effectiveness, the procedure is applied to three cases, one for which an exact solution is available, another for which field observations had been made, and a third one for which a parallel study was made, using an accepted limit-equilibrium method.

Jan 1, 1970

By R. P. Smith, L. S. Darken

FOR a high-purity iron-carbon alloy, the phases existing at equilibrium at temperatures slightly above the temperature of the metastable eutectoid are austenite and cementite (hyper-eutectoid) or austenite and ferrite (hypo-eutectoid) and those below the eutectoid temperature (carbdn content > 0.02 pct) are ferrite and cementite. Such an alloy, held in a carefully controlled and measured temperature gradient (about 1 cm per deg) which includes the eutectoid temperature, then quenched and examined metallographicall.y, provides a precise measure of the eutectoid temperature. The samples were hollow cylinders approximately 1.3 cm OD, 0.63 cm ID, and 2.5 cm long, which had been carburized to the desired carbon content at 1000°C with an appropriate hydrogen-methane mixture. In order to cool the samples to room temperature with a minimum change of carbon content and absence of cracks they were quenched in a Cerro Bend bath at 480°C, followed by a water quench to room temperature. Three cylinders were suspended in the furnace1 in a purified helium atmosphere, by a closed end, thin wall, silica tube which also served as a thermocouple well. The top and bottom cylinders served only as a means of making the temperature gradient along the center cylinder more uniform. The temperature was determined with a platinum-platinrhodium thermel calibrated by comparison with a thermel certified (* 0.5OC) by the National Bureau of Standards. After holding in the temperature gradient for 24 to 72 hr the samples were quenched in Cerro Bend at 480°C, followed by

Jan 1, 1960

By K. V. S. Sastry

INTRODUCTION Flotation is by far the most important unit operation of mineral processing. Most of the common base metals are produced from flotation concentrates of metal sulfides. Flotation is proving to be a valuable process for producing non-metallic minerals such as ceramic oxides, silicates, clays and phosphate fertilizers. All these fltation separations are carried out on materials which are predominantly in the 10 to 100 micronssize range. The present practice of flotation circuits for the production of large tonnages of metallic and non-metallic mineral concentrates is fairly well understood, developed, and standardized. Two kinds of problems are encountered (1, 2) with fine particles smaller than 10 microns. First is the interference of the fine particles with the flotation of the coarser particles and the second is the poor flotation behavior of fine particles. In general, these problems are handled either by eliminating, minimizing, or ignoring the fines in the flotation circuit feed. In recent years, however, a considerable number of experimental and theoretical studies have been carried out to understand the flotation behavior of fine particulates. This literature is summarized in four review papers (2-5). Application of the conventional flotation techniques for the separation of mineral fines is known to be uneconomical, and to present several scientific and technological problems (1-5). The objective of this presentation is to examine the flotation behavior of fine particles in terms of their physical-chemical properties and to review the potential techniques of fine particle flotation. Specific reference to the problem areas and research needs will also be included in the discussion.

Jan 1, 1979

By W. T. Burns

Attempts were made in 1908, at the Great Falls Works, to produce ingots direct from the Butte precipitate by smelting the material in a reverberatory refining furnace. The ingots produced in this manner averaged 99.4 per cent. of copper and 0.40 per cent. of arsenic and antimony. The copper content being considered too low, it was decided to cast the copper into anodes and to treat the anodes in the electrolytic plant. No. 1 Furnace, in which the precipitate was treated, was a regular cathode refining furnace previously employed in making wire bar, cake, and ingot from electrolytic cathodes. The hearth of the furnace was 24 by 12 ft., having a capacity of 100,000 lb. of cathodes. The furnace was coal fired, and the copper was dipped by means of trolley ladles. The average composition of the furnace charges was as follows: Per Cent. Peer Cent. Copper. Precipitate,..........7.5.3 40 to 80 Purification cathodes,.....1.9 92 Refinery slag (oxide slag),.. 10.1 50 to 60 Electrolytic cathodes,... 2.1 99.9 Precipitate anode scrap,.... 3.1 99.0 Scrap copper,.........7.5 99.2 100.0 The slag from this furnace amounted to 46 per cent. of the total amount charged and was of the following average composition: Per Cent. Cu..............16.86 SiO2.............34.7 FeO.............18.8 A12O3.............13.0 CaO.............9.4 MgO.............2.7 S............... 0.47 As..............0.11 Sb...............0.006 Ag, oz per ton.....0.18

Jan 1, 1914

By W. C. Winegard, C. J. Simpson

BNINGESSNER et al.1 have shown that the solidification substructure in dilute cadmium alloys persisted after repeated deformation, recrystallization, and annealing treatments. On the basis of this and similar evidence, Whelan has suggested in a recent publication' that the solidification structure might affect the mobility of grain boundaries even after primary re-crystallization. This suggestion is important, since the technique used by previous investigators3-5 to fabricate grain growth specimens consisted only of casting, deforming, and recrystallizing prior to the grain growth anneal. Usually no attempt was made to homogenize samples with prolonged annealing. Experiments. To test the Whelan hypothesis, grain growth experiments were performed with samples in which the degree of solute segregation was altered by controlling the solidification rate of the alloys. The initial experiments were performed on the Pb-Ag system. Alloys containing 0.01 at. pct Ag were produced from 99.9999 pct Pb and 99.999 pct Ag. Cylindrical samples, 40 cm long and 12 mm in diam, were solidified in graphite-coated Vycor tubes by lowering them through a vertical furnace at varying rates with the furnace power settings constant. Six-centimeter sections were discarded from each end, and the 28-cm section from the center was cut into sections 25 mm long for grain growth experiments. These samples were deformed with the aid of a drophammer to a uniform thickness of 5.7 mm. After almost instantaneous recrystallization, the samples were given a grain growth anneal for various times at 260°C in a salt bath. Experimental results are shown

Jan 1, 1970