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The Du Pont Magazine for August and September gives the following interesting information regarding recent progress in the use' of explosives. Blasting -Clay.-"The place where I tried blasting down clay for a brick yard had been worked for some years by old-time pick and shovel method. There was a large shallow pit, irregular in shape, with a perpendicular face at one end. I put down a line of holes 3 ft. deep and 6 ft. back from this face, loading each hole with one and one-half car-tridges of Red Cross Extra 40 per cent. dynamite. The charges were connected up to a blasting machine circuit and fired electrically. "Two of these shots kept the brick yard men very busy for two days taking out the loose clay. "I am convinced that if any brick yard man will try this method he will always have a blasting machine and dynamite on hand thereafter, because it cuts labor cost almost in two to get down the clay in. this way." In some clay pits the practice is to blast a large amount of clay in the fall, allowing it to freeze and thaw through the winter. Such clay is much easier to puddle in the spring than freshly dug or blasted clay. When the clay contains stones, the blasting loosens them and makes their separation-easy. Well-Drill Holes in Quarrying.-The well drill or cable drill method of working a quarry face is now in quite common use. The use of large drills is constantly increasing among quarrymen. In fact the growing tendency is for large machinery of all kinds such as mammoth crushers, steam shovels, etc. Volume is what is wanted nowadays. The advantages of the big drill over the piston driven drill are numerous. By carrying the holes the full depth of the face the stone is loaded and treated on one working floor. It eliminates the cost of bench cleaning. Loading operations are less frequent, thus lessening the danger. Stone can be shot down in greater volume and in better shape, making it economical to use a steam shovel. No bench cleaning makes it safer for the men. It is cheaper and can be used in outlying and temporary operations where the cost of installing a power plant would be out of the question. It permits a greater spacing of bore holes and eliminates the necessity of "squibbing" or springing. In this method usually holes from 4 in. to 6 in. in diameter are drilled the full depth of the face from 15 ft. to 2,0 ft. apart, and as far back and the whole face shot down at one time. The cost of well drilling may vary all the way from 20 cents to 75 cents: per foot, and in extremely hard rocks up to $1.50 per foot.

Jan 10, 1916

By H. R. Thresh

An oscillational vis cometer has been constructed to measure the viscosity of liquid metals and alloys to 800°C. An enclosed cylindrical interface surrounds the molten sample avoiding the free surface condition found in many previous measurements. Standardization of the apparatus with mercury has verified the use of Roscoe's formula in the calculation of the viscosity. Operation of the apparatus at higher temperatures was also checked using molten lead. Extensive measurements on five different samples of zinc, of not less than 99.99 pct purity, indicate i) impurities at this level do not influence the viscosity and ii) the apparatus is capable of giving reproducible data. The variation of the viscosity ? with absolute temperature T is adequately expressed by Andrade's exponential relationship ?V1/3 = AeC/VT , where A and C are constants and V is the specific volume of the liquid. The values of A and C are given as 2.485 x 10-3 and 20.78, 2.444 x 10-3 and 88.79, and 2.169 x 10-3 and 239.8, respectively, for mercury, lead, and zinc. The error of measurement is assessed to be about 1 pct. Prefreezing phenomena in the vicinity of the freezing point of the zinc samples were found to be absent. AS part of an over-all program of research on various phases of melting and casting nonferrous alloys, a systematic study of some physical properties of liquid metals and their alloys was undertaken in the laboratories of the Physical Metallurgy Division.1,2,3 The most recent phase of this work, on zinc and some zinc-base alloys, was carried out in cooperation with the Canadian Zinc and Lead Research Committee and the International Lead-Zinc Research Organization. One of the properties investigated was viscosity and the present paper gives results on pure zinc; the second part, on the viscosity of some zinc alloys, will be reported separately. Experimental interest in the viscosity of liquid metals has virtually been confined to the past 40 years. The capillary technique was already established as the primary method for the viscosity of fluids in the vicinity of room temperature; all relevant experimental corrections were known and an absolute accuracy of 1 to 2 pct was possible. Ap- plication of the capillary method to liquid metals creates a number of exacting requirements to manipulate a smooth flow of highly reactive liquid through a fine-bore tube. Consequently, the degree of precision usually achieved in the high-temperature field rarely compares with measurements on aqueous fluids near room temperature. However, the full potential of the capillary method has yet to be explored using modern experimental techniques. As an alternative, many investigators in this field have preferred to select the oscillational method. Unfortunately, the practical advantages are somewhat offset by the inability of the hydrodynamic theory to realize a rational working formula for the calculation of the viscosity. In attempting to overcome this restriction many investigators have employed calibrational procedures, even to the extent of selecting an arbitrary formula for use with a given shaped interface. However, where calibration cannot be founded on well-established techniques, the contribution of such experiments to the general field of viscometry is questionable. A critical appraisal of the viscosity data existing for pure liquid metals reveals a somewhat discordant situation where considerable effort is still required to establish reproducible and reliable values for the low-melting point metals. The means of rectifying this situation have gradually evolved in recent years. Here, the theory of the oscillational method has undergone major advances for both the spherical and cylindrical interfaces. The basic concepts of verschaffelt4 governing the oscillation of a solid sphere in an infinite liquid have been adequately expressed by Andrade and his coworkers.5,6 Employing a hollow spherical container and a formula, which had been extensively verified by experiments on water, absolute measurements on the liquid alkali metals were obtained. The extension of this approach to the more common liquid metals has been demonstrated by culpin7 and Rothwel18 where much ingenuity was used to surmount the problem of loading the sample into the delicate sphere. Because of the elegant technique required to construct a hollow sphere, the cylindrical interface holds recognition as virtually the ideal shape. On the other hand, loss of symmetry in one plane increases the complexity of deriving a calculation of the viscosity. The contributions of Hopkins and Toye9 and Roscoe10 have markedly improved the potential use of the cylindrical interface in liquid-metal viscometry. The relatively simple experi-

Jan 1, 1965

By R. V. Riley

IN the metallographic examination of the alloys of iron and silicon, several investigators1-' have reported on the occurrence of an unusual type of etched structure, particularly in the alloys of higher silicon content. This, the so-called "barley shell" structure, has been observed with iron-silicon alloys over a wide range of silicon content, and under certain circumstances it can be seen upon the micro-sections of pure iron. The barley shell structure may be demonstrated most easily with iron-silicon alloys in the range 8 to 20 pct Si after etching in a hydrofluoric acid base etchant. Two etchants which produce the structure are: Corson's reagent, which is 2 parts hydrofluoric acid, 1 part nitric acid, and 2 parts glycerol; and picric acid reagent, which is 1 part hydrofluoric acid and 1 part saturated solution of picric acid in alcohol. Both when freshly prepared and used for etching commercial silicon-iron alloys containing 14 to 16 pct Si, invariably produce the barley shell structure shown in Fig. la. It is now well known that the barley shell structure is a pseudomorph and the true structure of an alloy of this composition consists of a single phase of silico-ferrite together with graphite as shown in Fig. lb. Lower silicon alloys and even pure electrolytic iron may also be etched in the above reagents to give the barley shell provided the etchant has been either: 1—Stored in contact with glass or silica, or 2—used previously for etching an iron containing silicon. Pure iron etched in perfectly pure hydrofluoric acid base etchants free from silicon contamination gives a normal structure free from the barley shells. Therefore, although the hydrofluoric acid in the reagent primarily is responsible for the barley shells, silicon, or its compounds, also must be present, either in the etching reagent or in the specimen. It was of considerable interest to the author to read the paper by Wachtell,? in which the barley shell etch was deliberately used for the identification of the boundaries of high and low silicon areas in diffusion experiments made upon laminate bars of compacted and sintered pure iron and ferrosili-con powders. This method of utilizing the barley shell etch is novel and in the hands of the investigator gave a useful differentiation between the high and low silicon areas in those specimens. For the reasons already given, however, the technique is not to be regarded as of universal application. Misleading results might be obtained, for example, if two or more specimens were etched in the same etchant. Fresh pure reagents only must be used each time. Provided this is done and the investigators are well aware of the limitations of the method, then the barley shell pseudomorph can be made of limited use in distinguishing between higher and lower silicon areas in a microspecimen of a ferrous material. The greatest of care must be exercised in the interpretation of the results which may be regarded as qualitative only and may, in fact, not be specific to silicon alloys.

Jan 1, 1952

By M. T. Hepworth, A. K. Stewart

Iron containing 0.1 pct A1 and -0.9 pct P by weight was internally oxidized in the temperature range 900° to 1300° C, where the bcc structure is stabilized by phosphorous. By measuring the depth of penetration of oxygen with time in an internally oxidized zone for an imposed surface oxygen potential, oxygen permeability was determined. The dgfusion coefficient of oxygen in iron was then calculated using known solubility data, yielding the expression: where Do is the diffusion coefficient of oxygen in bcc iron in sq cm per sec and T is temperature in OK. RECENTLY Hepworth, Smith, and Turkdoganl measured the diffusivity of oxygen in bcc iron and reported the temperature dependence of diffusivity from data determined in the a, and 6 temperature ranges. Subsequently Swisher and Turkdogan' have measured the diffusivity of oxygen in fcc iron. Internal oxidation techniques were employed by these investigators and in this current study. The analysis of this technique is developed by wagner3 (presented in English by Hauffe4 and Rapp 5). In this present study bcc iron stabilized by phosphorous was used to determine oxygen diffusivity in the temperature range 900° to 1300°C. Meijerin 6 has studied oxygen permeability in this temperature range using bcc iron stabilized with 5 pct Sn. Other inves- tigators who have studied oxygen permeability in bcc iron at other temperatures are Schenck et al., 7 Bohen-kamp and Engell, 8 and Bradford. EXPERIMENTAL Electrolytic iron of 99.99 pct purity was alloyed to contain 0.897 pct P and 0.093 pct Al. The maximum weight percent phosphorous required to stabilize bcc iron between 910" and 1392°C is 0.51 pct as determined by Haughton,10 0.42 pct by Roquet and jegaden," and 0.58 pct by vogel,12 with the latter value preferred by Hansen.13 Microprobe analysis indicated that there was no segregation of the phosphorous either before or after permeability studies; therefore, the quantity of phosphorous added was assumed to be sufficient to stabilize the bcc structure. Furthermore, the permeability results of studies on this alloy agreed substantially with interpolated values from previous data on bcc iron.' An ingot of the Fe-P-A1 alloy was hot-rolled to a l-in.-thick slab. Specimens were machined to dimensions: 13/8 by $ by 1/4 in. The experimental apparatus and procedure used have been described before.' A constant oxygen potential was established by passing argon and hydrogen through a column of oxalic acid dihydrate, which has a water vapor pressure which is well-known as a function of temperature. Slab specimens were exposed to a gas mixture sufficiently lean in oxygen to prevent the formation of a surface oxide for predetermined temperature for selected times. The specimens were then quenched, sectioned, and examined metallo-graphically. All quenched specimens were iron-plated to provide protection from the outside sample edge during polishing. Fig. 1 shows a typical microstruc-ture for a specimen oxidized at 953°C for 48.00 hr at a water vapor-to-hydrogen pressure ratio of 0.20. DISCUSSION AND RESULTS The following equation was derived by Hepworth et al.' from Wagner's kinetic expressions for internal oxidation:

Jan 1, 1969

By F. M. Lewis, R. B. Bhappu

In 1977 a paper was presented which reviewed the cost trends in producing copper by conventional processes for five years, 1972 through 1976. In this paper these costs have been updated to include the years 1977 and 1978.

Jan 1, 1982

By Conrad W. Stellar, John L. Paynich

Design/Build concept that provides for earliest possible completion and lowest cost is presented. Elements of the program include: joint cooperation between owner, designer and builder; schedule construction sequence; and a line budget. Benefits over lump sum contracts are reviewed.

Jan 1, 1979

By O. P. Hood

None of the methods now in use for the transportation of materials underground is entirely free from more or less serious objection.

Jan 1, 1915

By David T. Day

In 1897 I published a proposed explanation for the variation in color and specific gravity of Pennsylvania oils. A resume of this subject mas also presented at the First International Petroleum Congress, in Paris, in 1900. Since that time

Jan 1, 1911

By J. H. Henderson, J. Naar

The displacement of a wetting fluid from a porous medium by a non-wetting fluid (drainage) is now reasonably well understood. A complete explanation has yet to be found for the analogous case of a wetting fluid being spontaneously imbibed and the non-wetting phase displaced (imbibition). During the displacement of oil or gas by water in a water-wet sand, the porous medium ordinarily imbibes water. The amount of oil recovered, the cost of recovery and the production history seem then to be controlled mainly by pore geometry. The influence of pore geometry is reflected in drainage and imbibition capillary-pressure curves and relative permeability curves. Relative permeability curves for a particular consolidated sand show that at any given saturation the permeability to oil during imbibition is smaller than during drainage. ' Low imbibition permeabilities suggest that the non-wetting phase, oil or gas, is gradually trapped by the advancing water. This paper describes a mathematical image (model) of consolidated porous rock based on the concept of the trapping of the non-wetting phase during the imbibition process. The following items have been derived from the model. 1. A direct relation between the relative permeability characteristics during imbibition and those observed during drainage. 2. A theoretical limit for the fractional amount of oil or gas recoverable by imbibition. 3. An expression for the resistivity index which can be used in connection with the formula for wetting-phase relative permeability to check the consistency of the model. 4. The Iimits of flow performance for a given rock dictated by complete wetting by either oil or water. 5. The factors controlling oil recovery by imbibition in the presence of free gas. The complexity of a porous medium is such that drastic simplifications must be introduced to obtain a model amenable to mathematical treatment. Many parameters have been introduced by others in Iprogressing" from the parallel-capillary model to the randomly interconnected capillary models independently proposed by Wyllie and Gardner3 and Marshall4. To these a further complication must be added since an imbibition model must trap part of the non-wetting phase during imbibition of the wetting phase. Like so many of the previously introduced complications, this fluid-block was introduced to make the model performance fit the observed imbibition flow behavior. THE IMBIBITION MODEL ASSUMPTIONS The following assumptions are common to many two-phase models previously described. 1. The wetting characteristics of the medium are clearly defined. 2. When two fluids co-exist in the medium, the wetting phase will fill the smaller pores and the non-wetting fluid the bigger ones. 3. The pores have a circular cross section. 4. Apparent pore radii are related to the capillary pressure (drainage) by

By D. D. Todd, W. A. Oates

THERMODYNAMIC data for solutions are best derived from a combination of equilibrium and calorimetric studies. However, the accurate measurement of heats of mixing of metallic solutions at high temperatures presents considerable experimental difficulties, simple calorimeters1-3 giving

Jan 1, 1964

By C. E. Lesher

THIS paper reports a study of the reactivity of 950°F and 1650°F cokes as measured by relative rates of reduction of iron oxides at temperatures up to 2200°F. Previous work cited shows general acceptance of the theory that reduction by carbon is a gaseous reaction, and that kind and character of carbon as well as particle size have measurable effect on the velocity of reaction. As will be shown, the data obtained in this study confirm those conclusions. The work was not designed to examine iron oxide reduction equilibrium, but if reaction velocity be defined as the speed with which "a reaction tends to approach conditions of equilibrium," the data here presented may be considered as a study of reaction rates, and the relative degree of reduction to metallic iron as the measure of reactivity. Three standardized combinations of Lake Superior brown iron ore with carbon were tested by similar procedures. One combination was a mechanical mixture of carefully sized high-temperature coke (1650°F) with the ore. The second was a mechanical mixture of the ore with Disco* obtained by carbonizing the identical coal at 950 °F. The third was an agglomerate prepared by carbonizing the coal and ore at 950°F, premixed in proportions to give as nearly as possible the same relative amounts of carbon and ore as the mechanical mixtures. This agglomerate, obtained by heating the finely divided ore (through 30 mesh) with coking coal through the plastic temperature range so as to form solid aggregates, gives a product in which the oxide particles are impregnated with, and intimately bound together with low-temperature coke. The agglomerate-—ore-Disco—was most active in oxide reduction; the mechanical mixtures of Disco and ore next in order, with coke the least reactive. General Discussion: Carbon exists in many forms and it is well known that the form or nature of the carbon used in reduction of oxides is related to the critical temperature of reduction. Sugar carbon, charcoal, and lampblack are forms of carbon that will reduce oxides at lower temperatures than high-temperature coke, and coke will, in turn, give a lower critical reduction temperature than graphite. There have been many investigations of this characteristic of carbons. Johnson' reported a difference of 130°F (70°C) in the critical reduction temperature of zinc oxide as between charcoal 1891 °F (1033°C) and Acheson graphite turnings 2021°F (1105°C) with zinc oxide. Bodenstein2 using charcoal and coke, found a difference of 138°F (77°C) comparing an experimental figure of 2066°F (1130°C) for coke and 1928°F (1053°C) for charcoal, in the reduction of zinc oxide. He concluded that this is very marked and observed that the "type of carbon merely raises or lowers the temperature at which rapid reaction takes place." Comparing the effectiveness of types of carbon in reduction of zinc oxide, it was found that a "brown coal coke" gave 97 pct zinc elimination at 1832°F (1000°C), as compared with 48 pct with "hard coal coke."' A wide range of metallic oxides was studied by Tammann and Sworykin,4 who found that the temperature at which decomposition of oxides begins depends on the nature of the carbon used. Carbon in the form of graphite, lampblack, and sugar carbon was investigated. Sugar charcoal will reduce Fe2O3 to Fe3O4 at 842°F (450°C) as compared with 1112°F (600°C) for coke, according to Meyer." Direct reduction of iron oxides by charcoal begins at 1382°F (750°C), but "first becomes intense" at 1652°F (900°C), whereas with coke, direct reduction begins at 1742°F (950°C), and "first becomes appreciable" at 2012°F (1100°C).6 he total reduction of the sample under certain conditions when heated in a current of CO with charcoal was about 100 pct for limonite and about 77 pct for magnetite. Using coke under the same conditions, the respective percentages were 75 and 47. In a study of processes for sponge iron7 by the Bureau of Mines, the conclusion was reached that a low-temperature char from noncoking subbituminous coal is the most satisfactory solid reducing agent. In a critical study of zinc smelting from a theoretical viewpoint Maier8 concluded that the reduction is by CO, that the reaction between ZnO and CO is intrinsically more rapid than the subsequent reduction of CO2 by C, which is limited by diffusion rates, which in part effectively limits the smelting process. Maier said that the operation is improved with the activity of the reducing carbon. An active carbon, he said, is one maintaining a low CO, content in the retort. Reactivity of Carbon: One form of carbon is more potent in reducing oxides than another. A carbon that reacts faster than another at a given temperature is said to be more reactive. Reactivity is measured by several methods, using carbon dioxide, air, or steam as reactants.9 ebastian and Mayers" have developed a method for the determination of absolute reaction rates between coke and oxygen by a study of ignition points under certain conditions. These and other investigators have established the relative reactivity of types of carbon. Lignite, charcoal, bituminous coal, cokes in the ascending order

Jan 1, 1951

By C. E. Lesher

THIS paper reports a study of the reactivity of 950°F and 1650°F cokes as measured by relative rates of reduction of iron oxides at temperatures up to 2200°F. Previous work cited shows general acceptance of the theory that reduction by carbon is a gaseous reaction, and that kind and character of carbon as well as particle size have measurable effect on the velocity of reaction. As will be shown, the data obtained in this study confirm those conclusions. The work was not designed to examine iron oxide reduction equilibrium, but if reaction velocity be defined as the speed with which "a reaction tends to approach conditions of equilibrium," the data here presented may be considered as a study of reaction rates, and the relative degree of reduction to metallic iron as the measure of reactivity. Three standardized combinations of Lake Superior brown iron ore with carbon were tested by similar procedures. One combination was a mechanical mixture of carefully sized high-temperature coke (1650°F) with the ore. The second was a mechanical mixture of the ore with Disco* obtained by carbonizing the identical coal at 950 °F. The third was an agglomerate prepared by carbonizing the coal and ore at 950°F, premixed in proportions to give as nearly as possible the same relative amounts of carbon and ore as the mechanical mixtures. This agglomerate, obtained by heating the finely divided ore (through 30 mesh) with coking coal through the plastic temperature range so as to form solid aggregates, gives a product in which the oxide particles are impregnated with, and intimately bound together with low-temperature coke. The agglomerate-—ore-Disco—was most active in oxide reduction; the mechanical mixtures of Disco and ore next in order, with coke the least reactive. General Discussion: Carbon exists in many forms and it is well known that the form or nature of the carbon used in reduction of oxides is related to the critical temperature of reduction. Sugar carbon, charcoal, and lampblack are forms of carbon that will reduce oxides at lower temperatures than high-temperature coke, and coke will, in turn, give a lower critical reduction temperature than graphite. There have been many investigations of this characteristic of carbons. Johnson' reported a difference of 130°F (70°C) in the critical reduction temperature of zinc oxide as between charcoal 1891 °F (1033°C) and Acheson graphite turnings 2021°F (1105°C) with zinc oxide. Bodenstein2 using charcoal and coke, found a difference of 138°F (77°C) comparing an experimental figure of 2066°F (1130°C) for coke and 1928°F (1053°C) for charcoal, in the reduction of zinc oxide. He concluded that this is very marked and observed that the "type of carbon merely raises or lowers the temperature at which rapid reaction takes place." Comparing the effectiveness of types of carbon in reduction of zinc oxide, it was found that a "brown coal coke" gave 97 pct zinc elimination at 1832°F (1000°C), as compared with 48 pct with "hard coal coke."' A wide range of metallic oxides was studied by Tammann and Sworykin,4 who found that the temperature at which decomposition of oxides begins depends on the nature of the carbon used. Carbon in the form of graphite, lampblack, and sugar carbon was investigated. Sugar charcoal will reduce Fe2O3 to Fe3O4 at 842°F (450°C) as compared with 1112°F (600°C) for coke, according to Meyer." Direct reduction of iron oxides by charcoal begins at 1382°F (750°C), but "first becomes intense" at 1652°F (900°C), whereas with coke, direct reduction begins at 1742°F (950°C), and "first becomes appreciable" at 2012°F (1100°C).6 he total reduction of the sample under certain conditions when heated in a current of CO with charcoal was about 100 pct for limonite and about 77 pct for magnetite. Using coke under the same conditions, the respective percentages were 75 and 47. In a study of processes for sponge iron7 by the Bureau of Mines, the conclusion was reached that a low-temperature char from noncoking subbituminous coal is the most satisfactory solid reducing agent. In a critical study of zinc smelting from a theoretical viewpoint Maier8 concluded that the reduction is by CO, that the reaction between ZnO and CO is intrinsically more rapid than the subsequent reduction of CO2 by C, which is limited by diffusion rates, which in part effectively limits the smelting process. Maier said that the operation is improved with the activity of the reducing carbon. An active carbon, he said, is one maintaining a low CO, content in the retort. Reactivity of Carbon: One form of carbon is more potent in reducing oxides than another. A carbon that reacts faster than another at a given temperature is said to be more reactive. Reactivity is measured by several methods, using carbon dioxide, air, or steam as reactants.9 ebastian and Mayers" have developed a method for the determination of absolute reaction rates between coke and oxygen by a study of ignition points under certain conditions. These and other investigators have established the relative reactivity of types of carbon. Lignite, charcoal, bituminous coal, cokes in the ascending order

Jan 1, 1951

By D. P. Pope, T. Vreeland

Observations of dislocations in zinc using Berg-Barrett X-ray micrography confirm the validity of a dislocation etch for (1010) surfaces. A technique for measurement of the depth in which dislocations can be imaged in X-ray micrographs is given. This depth on (0001) surfaces of zinc was found to be 2.5 µ using a (1013) reflection and CoKa radiation. BUCHANAN and Reed-Hill (B & RH) have recently questioned the ability of a dislocation etch to reveal all of the basal dislocations which intersect (1010) surfaces in annealed zinc crystals.' This etch was developed by Brandt, Adams, and Vreeland who conducted a number of different experiments to check its ability to reveal dislocations.2,3 B & RH prepared (0001) foil specimens for transmission electron microscopy from annealed crystals and observed dislocation densities of about l08 cm per cu cm in the foils, while the etch indicated densities of the order of l04 cm per cu cm in their annealed crystals. As this etch has been used in a number of studies of dislocations in zinc, it is of considerable importance to reassess its validity in the light of the B & RH results. The X-ray work reported here was undertaken to check the ability of the etch to reveal dislocation intersections on (1070) surfaces of zinc. The X-ray technique was chosen for this check because it could be applied to the as-grown crystals with a relatively small amount of specimen preparation. We believe that the possibility of accidental deformation in preparation of the bulk specimens is considerably less than that for thin foil specimens suitable for transmission electron microscopy. Unfortunately, basal dislocations are not visible on Berg-Barrett topo-graphs of (1010) surfaces, which are the surfaces on which the etch is most effective. Therefore, a one-to-one correspondence between the etch and X-ray observations could not be made. Basal dislocations near (0001) surfaces have been observed by Schultz and Armstrong4 using the Berg-Barrett technique, but they did not report the as-grown dislocation density observed in their crystals. We have applied the X-ray technique in this study to surfaces oriented from 1 to 2 deg of the (0001) to determine the basal dislocation density, and have compared this density with that observed using the etch on a (1070) plane of the same crystal. The X-ray observations permit determination of the depth in which basal dislocations can be observed under the diffracting conditions used. SPECIMEN PREPARATION High purity zinc crystals are very soft, so a good deal of care must be exercised in the preparation of observation surfaces. As-grown crystals approximately 2.5 cm in diam and 20 cm long were acid cut into 1.25 cm cubes. A thin slab was cleaved from an (0001) surface to produce an accurately oriented reference surface on the specimen. Some of the cubes were examined in the as-machined condition while some were annealed in argon at 410°C for 2 hr. Heating and cooling rates were less than 2°C per min. Some of the specimens were scratched on a (0001) surface with a razor blade to produce fresh dislocations. Approximately 2 mm of material was acid lapped from one face of a cube to produce a surface oriented between 1 and 2 deg from the basal plane and parallel to the [1210] direction. A (1070) surface was also acid lapped. The lap used a 1 to 3 pct solution of HN03 in water to saturate a soft cloth which was backed by a stainless steel plate. The cloth was moved over the crystal surface at a rate of 20 cm per sec while a normal force of about 4 g was maintained between the cloth and the specimen. As-lapped surfaces were examined as were surfaces which were chemically and electrolytically polished after lapping. The small angle between a lapped surface and the (0001) plane was measured to 0.1 deg using a Unitron microgoniometer microscope (the cleaved surface was used as a reference in this measurement). The microscope was modified so that the intensity of reflected light could be continuously monitored on a meter. This modification produced nearly a ten-fold increase in the reproduceability of orientation readings. OBSERVATIONS The Unitron Microgoniometer observations indicated that the lapped surfaces had a terraced structure with the terraces quite rounded and spaced about 0.1 mm in the [1010] direction. The maximum change in slope between terraces was 0.25 deg, indicating a terrace height of about 0.1 µ. A Unitron measurement of the average angle between (0001) and a lapped surface was checked by micrometer measurement of the specimen and found to agree within 0.1 deg. The Berg-Barrett micrographs using (1013) reflections and CoKa radiation5 revealed subboundaries, short dislocation segments, spirals, and loops near the surfaces which were oriented from 1 to 2 deg of the (0001). Micrographs of surfaces prepared by lapping appeared very similar to those of the chemically and electrolytically polished surfaces. The loops and spirals were not extinct in (1013) or (0002) reflections, indicating that they have a nonbasal Burgers vector. Extinctions of the short, straight dislocations indicated that they belonged to an (0001)(1210) system. Fig. 1 is an example of a micrograph which shows a subboundary, and dislocation segments which are pre-

Jan 1, 1970

By L. J. Boucher

The beneficiation process at Northampton is described and reasons are given for installing a flotation plant. The economics of running the plant, the difficulties of operation, and subsequent remedial action are discussed.

Jan 3, 1953

In the 100' years since AIME was founded in 1871, the Institute has issued a great many publications in a variety of forms: periodicals, Transactions volumes, and special volumes or books. The following is a brief history of AIME publishing with some suggestions for proper referencing. TRANSACTIONS AIME Transactions volumes have been numbered consecutively since No. 1 was issued in 1873, including papers for the period 1871-1873. One or more volumes have been issued each year and may be divided into three general time periods: General Volumes (1873-1927), Volumes classified by subject matter (1928-1949), and the present practice, begun in 1949, of issuing three volumes per year, one each in the fields of mining engineering, metallurgy, and petroleum technology. The broad divisions of subject matter in each of these volumes correspond to the technical areas of the three constituent societies of AIME. AIME's Technical Publications, usually designated by TP number's (until the change in numbering system by the Society of Mining Engineers in 1958), may, with some exceptions, be referenced to an AIME Transactions volume. Reference to a specific volume, rather than paper number, is the preferred reference, since the volumes are the form of publication most commonly available in libraries. In many cases, over the years, the Technical Publications may also have been available in some other form, either as separates or in a periodical. General. Volumes (Vols. 1-78, 1873-1927): Until 1927 all papers eligible for Transactions were published in general volumes with no systematic attempt made to segregate the material on the basis of the technological fields to which the papers related.. One volume per year was issued from 1873 until 1912; from 1912 until 1927 from two to four volumes were issued annually. In addition to the Transactions papers, these volumes carried some of the proceedings of the business meetings of AIMS. Subject Volumes. (Vols. 79-183; 1928-1949): The material for these volumes was segregated according to subject matter, and up. to seven volumes were issued a year. In the latter part of the period, from 1934 on, there was one volume each' year for the Petroleum, Institute of Metals, and Iron and Steel Divisions and-the remaining papers were grouped in various ways and is sued whenever sufficient numbers of papers had accumulated: The subject volumes containing mining engineering papers are listed in Table 1. The volumes for the period, 1936-1949 are included in this Cumulative Index. Each of the Transactions volumes carries on the binding the year of publication; this date does not give an indication of when the papers included were originally presented at meetings. The contents of the volumes usually list the meetings at which. the papers were presented. Not all papers from a given meeting necessarily are in one Transactions volume. Some of the earlier volumes do not have a number on the binding or within the volume. In 1934 numbers" were assigned to all Transactions volumes, commencing with the 1871-1873 volume as No. 1. Many of the papers published [ ]

Jan 1, 1972

By P. Marier, T. R. Ingraham

When anhydrous cupric sulfate is heated in a stream of nonreactive gas, cupric oxysulfate is formed. When this reaction is complete, the cupric oxysulfate then decomposes to cupric oxide, which is the normal end product of reaction. The kinetics of each of these reactions has been studied using pellets prepared from finely divided cupric sulfate and from finely divided cupric oxysulfate. In each case, the reactant-product interface within the pellet is well-defined, and by normalizing the decrease in inter facial area with the weight fraction of the pellet decomposed it has been shown that the interface migrates into the pellet at a uniform rate at constant temperature. The activation energy estirnated for the decomposition of cupric sulfate is 57 ± 7 kcal per mole and that for cupric oxysulfate is 67 ± 8 kcal per mole. The rate of interfacial reaction is flow-sensitive, increasing with increasing flow of a sweep gas in the range from 50 to 2000 cu cm per min. The rate of decomposition is retarded by sulphur trioxide in the sweep gas. The relationship between sulfur trioxide Partial pressure and rate is consistent with the Langmuir Adsorption Isotherm governing the retention of sulfur trioxide in the interfacial layer. MOST of the work reported on the thermal decomposition of cupric sulfate and of cupric oxysulfate is related to the thermodynamics of the individual decompositions.'-4 No information is available on the rates of the individual reactions, on their activation energies, or on the effects of gas flow or of partial pressure of sulfur trioxide on the reaction rates. Some dubious conclusions based on relative reaction rates have been drawn from studies on the oxidation of sulfides. For example, on the basis of the products observed in a quenched system, it has been suggested5" that, when copper sulfide is roasted, the cupric oxide which is formed arises from the decomposition of either cupric sulfate or cupric oxysulfate. This is very difficult to reconcile with the thermodynamics of the C-S-O System,3 which support the probability that both cuprous oxide and cupric oxide precede cupric oxysulfate and cupric sulfate in the sequence of products formed during the oxidation of cuprous sulfide. In this paper the individual sulfate decomposition reactions will be examined and suggestions will be advanced for the mechanism of reaction. This will be based on the effects on reaction rate of changes in interfacial area, flow rate, and back-pressure of sulfur trioxide. EXPERIMENTAL Materials. The copper source material used in all experiments was Fisher Certified Reagent Grade anhydrous cupric sulfate, for which the following analysis was supplied by the manufacturer: chloride, 0.002 pct; alkalies and earths, 0.2 pct; insoluble, 0.002 pct; iron, 0.020 pct. Cupric oxysulfate was prepared by roasting cupric sulfate for 48 hr, with frequent rabbling, in an open tray in a muffle furnace maintained at 725°C. At this temperature, cupric sulfate develops about 0.16 atm pressure of combined sulfur trioxide, sulfur dioxide, and oxygen. Cupric oxysulfate develops only about 0.05 atm pressure, and is stable until

Jan 1, 1965

By J. C. Allen, E. V. Herring

CHILE EXPLORATION CO's. oxide plant at Chuquicamata, the largest of its kind, started in 1915 with initial operations at the rate of 10,000 tons of ore per day. Anaconda Copper Mining Co. acquired the controlling interest in 1923 and in the next few years modernized the plant and mine, extending operations to a nominal capacity of 490 million lb of electrolytic copper yearly by 1942. Plant production averaging 495.7 million lb of copper per year was maintained for the eight-year period extending from 1941 to 1948 inclusive. During the World War II production reached its highest level when in 1944 the output was 531.8 million lb. The maximum production for any one month was 49.6 million lb, achieved in May 1947. E. A. Cappelen Smith, consulting metallurgist for M. Guggenheim's Sons, worked out the first process for the treatment of Chuquicamata copper oxide ore about 1913, and directed a staff of 20 young engineers operating a pilot plant at Perth Amboy, N. J., on three shifts for an entire year. The copper is extracted from the oxide ore by a hydro-metallurgical treatment described in detail by T. A. Campbell in AIME Transactions, Vol. 106, Copper Metallurgy, 1933. The Oxide Plant is divided into five main operations as follows: (1) Crushing, (2) Leaching, including dechloridizing and sulphur dioxide treatment, (3) Tailing disposal, (4) Electrolytic precipitation, (5) Smelting and melting. Crushing The present Primary Crushing Plant has been in operation 25 years, during which time 4,342,112 cars of 70 tons net capacity have passed through the dumpers. The ore as received from the mine is frequently blocky and up to 5 feet in section. It is reduced to 9-in. size by two 60-in. gyratory crushers, and transported to the east and west ore bins by 60-in. conveyors. In the secondary crushing operation the ore is first reduced to 2 to 3-in. size by five standard 7-ft cone crushers and two No. 10 gyratories. This product is then reduced to 3/8-in. size by fifty-two 48-in. vertical Symons disc crushers and is transported by belt conveyors to the loading bridges from which it is charged° into the leaching vats. Conveyor belt No. 14 which serves the eight vats in the east section of the leaching plant has transported over 125 million tons of ore, which is a record for any type of conveyor. This 60-in. belt travels at a speed of 600 fpm and carries loads up to 5500 tons per hr. Leaching The ore is leached in 14 vats, averaging 13,500 short tons net capacity each. These vats are lined with a natural mastic which adequately resists the sulphuric acid leaching solutions. The leaching process as presently conducted comprises soaking the ore with successive volumes of leaching solution and spent electrolyte and withdrawing successive volumes of enriched solution from the vat to a total of approximately 3.2 million gal. The first 1.6 million gal of this volume withdrawn is called strong solution and contains about 35 parts of copper per 1000. The balance of 1.6 million gal subsequently withdrawn is stored in a

Jan 1, 1952

By K. F. G. Hosking

I read Professor Gaudin&apos;s paper with great interest and pleasure because for some time I have held that the chemical aspect of comminution is a subject of considerable importance to the mineral dresser and deserves to be thoroughly investigated. It does seem appropriate, however, to emphasize the fact that "fresh" edges and corners produced by the grinding of solids display enhanced reactivity has been recognized and utilized in the development of certain mineral identification techniques. Some of these techniques are worth noting, not only because they might facilitate research in the aspect of mineral dressing under discussion, but also because they emphasize the fact that many mineral species commonly regarded as being very inert can display a surprising reactivity when in the freshly ground state. In 1951 Isakov6 published a number of tests for the components of certain mineral species which depend essentially on grinding in a mortar a mixture of the material under investigation with a solid reagent. Thus when stibnite, 4(Sb2S3), is ground with sodium or potassium hydroxide. the antimony is revealed by a momentary development of a yellow color which changes in air to orange-red. Other antimony minerals need a preliminary treatment before the test can be carried out. This consists of grinding with aluminium sulfate, ferric sulfate or potassium bisulfate, and breathing upon the resultant mixture. I have employed a similar technique to determine the approximate magnesia content of certain limestones.&apos; The method depends essentially on the fact that when a sample of limestone is ground under controlled conditions with solutions of sodium hydroxide and Titan yellow the color of the final product is, within limits, a function of the amount of magnesia present. I have also shown that the components of a wide range of minerals can be identified by applying chemicals to their streaks on portions of vitrified, unglazed floor tiles, etc. Under such circumstances the diversity of the reactions which take place in the cold (because of the reactivity of fresh corners and edges) is surprising. Thus, for example, if a garnierite, (Ni,Mg)3Si2O5(OH)1, streak is treated first with a drop of 0.880 ammonia and then with a drop of a 1 pct alcoholic dimethyl-glyoxime it immediately becomes red, indicating the presence of nickel.&apos; Stevens and Carron9 have evolved a simple field test for distinguishing minerals by "abrasion pH." A soft nonabsorbent mineral is scratched in a drop of water on a streak plate until a milky suspension is formed. A piece of pH indicator paper is dipped into the suspension, after which it is removed and the maximum deviation from neutrality noted. When a hard mineral or one which absorbs water is being tested, fragments are first ground for 1 min with a few drops of water in a mortar to make a heavy suspension. The importance of the findings of such tests to mineral dressing may be judged by the abrasion pH values, Table 11, recorded by Stevens and Carron for certain species usually regarded as comparatively inert. The combined results Of the above researches clearly indicate that comminution is capable of altering the pH of a pulp and of causing the chemical nature of the surfaces of some of the components to be profoundly changed&apos; Depending On circumstances such surface alterations may have a beneficial or an adverse effect if these products are subsequently subjected to flotation. The tests also suggest that by grinding "inert" minerals with appropriate solid or liquid reagents "reactive" surfaces may be developed which might facilitate separations by flotation. It is an interesting and instructive problem to determine the reactions that are likely to take place when dry solid substances are subjected to comminution and to the unavoidable heat liberated during the process. To do this it is theoretically necessary to know the free energy values of the reactants and possible resultants, but unfortunately there is a dearth of such data! However, the heats of formation of many substances are known, and generally speaking, if in a reaction of the type AB + CD = AD + CB the sum of the heats of formation of AB and CD is less than that of AD and CB the reaction will probably proceed to the right. Thus, according to a note I have (the author of which I cannot name) if PbS (black) is warmed with CdSO, (white), PbSO., (white) and CdS (yellow) are formed, and that the reaction does, in fact, take place is indicated by the change in color of the mixture. The reaction is expected, as the sum of the heats of formation of PbS and CdSO, is less than that of PbSO, and CdS (as shown below). PbS + CdSO4 = PbSO4 + CdS 22.2 + 218.0 < 216.2 + 33.9 Finally, certain other aspects of the chemistry of comminution, which are neither mentioned by Professor Gaudin nor referred to by me are to be found in a paper by Welsh" and in the printed discussion thereof. A. M. Gaudin (author&apos;s reply)—The observations contributed by Dr. Hosking are indeed welcome, as they add to our experimental knowledge of a topic which is believed to be of the first importance. In connection with the experiments cited it should be kept in mind that oxidation, hydration, and carbonation at various rates should always be deemed to be possibilities when grinding is done in water or in air, even in "industrially dry" air. Special precautions might lead to sufficient minimizing of these reactions and to the assertion, instead, of deliberately-created reactions. The author wishes to thank Dr. Hosking for his contribution.

Jan 1, 1957

By D. K. Crampton, H. I. Burghoff, J. T. Stacy

The effect of cold-working upon electrical conductivity of copper and of copper alloys appears not to be generally known in detail. Although several papers on the subject have been presented, showing variable effects according to alloy composition, it is often assumed that the 2 to 3 per cent lowering of the conductivity of ordinary tough-pitch copper by severe cold-working is typical for copper alloys. Because of this situation it was decided to carry out the present work upon several types of copper, copper-zinc alloys over the commercial range of brasses, other binary alloys, and numerous age-hardening alloys in the quenched, and quenched and aged conditions. The large number of alloys investigated made it impossible to study every one in the detail it may have merited. Inasmuch as several interesting points that could not be satisfactorily explained came to light, further work is contemplated by the authors. It is usually considered that the normal effect of cold-work on ductile metals and unordered alloys is to decrease conductivity slightly. In alloys that are in the ordered state, as annealed or otherwise heat-treated, cold--working tends to disorder the structure, resulting in very marked lowering of conductivity. The random state of atomic arrangement produces lower con- ductivity than the ordered state for the same composition.1 Previous Work Previous work in the authors&apos; laboratory has shown the electrical conductivity of several copper alloys to be decreased by greater amounts than might have been expected, in view of the general knowledge on the subject, when cold-worked. Guillet and Ballay2 investigated the influence of cold-work upon the resistivity of several metals and alloys, including copper and some copper alloys. The increase of resistivity due to severe working w is less than 4 per cent for all pure metals tested, while the increases for the alloys were generally higher. In the copper-zinc alloys, they found that the increase of resistance due to drawing increased with zinc content, and reported a 21.7 per cent increase of resistance for an alloy contaiiiing 67.9 per cent Cu as severely worked. Masima and Sachs3 studied the change in electrical resistance of three brass crystals when stretched in the tensile test, obtaining increases in resistance of the order of 3 per cent for 30 to 40 per cent reduction of area of the specimens. The resistance decreased again when the cold-worked crystals were subsequently annealed. Bardenheuer and Schmidt4 found that the conductivity of copper was decreased by 3 to 4 per cent when reduced 50 per cent by working. The conductivity of 72-28

Jan 1, 1941

By D. K. Crampton, H. I. Burghoff, J. T. Stacy

The effect of cold-working upon electrical conductivity of copper and of copper alloys appears not to be generally known in detail. Although several papers on the subject have been presented, showing variable effects according to alloy composition, it is often assumed that the 2 to 3 per cent lowering of the conductivity of ordinary tough-pitch copper by severe cold-working is typical for copper alloys. Because of this situation it was decided to carry out the present work upon several types of copper, copper-zinc alloys over the commercial range of brasses, other binary alloys, and numerous age-hardening alloys in the quenched, and quenched and aged conditions. The large number of alloys investigated made it impossible to study every one in the detail it may have merited. Inasmuch as several interesting points that could not be satisfactorily explained came to light, further work is contemplated by the authors. It is usually considered that the normal effect of cold-work on ductile metals and unordered alloys is to decrease conductivity slightly. In alloys that are in the ordered state, as annealed or otherwise heat-treated, cold--working tends to disorder the structure, resulting in very marked lowering of conductivity. The random state of atomic arrangement produces lower con- ductivity than the ordered state for the same composition.1 Previous Work Previous work in the authors&apos; laboratory has shown the electrical conductivity of several copper alloys to be decreased by greater amounts than might have been expected, in view of the general knowledge on the subject, when cold-worked. Guillet and Ballay2 investigated the influence of cold-work upon the resistivity of several metals and alloys, including copper and some copper alloys. The increase of resistivity due to severe working w is less than 4 per cent for all pure metals tested, while the increases for the alloys were generally higher. In the copper-zinc alloys, they found that the increase of resistance due to drawing increased with zinc content, and reported a 21.7 per cent increase of resistance for an alloy contaiiiing 67.9 per cent Cu as severely worked. Masima and Sachs3 studied the change in electrical resistance of three brass crystals when stretched in the tensile test, obtaining increases in resistance of the order of 3 per cent for 30 to 40 per cent reduction of area of the specimens. The resistance decreased again when the cold-worked crystals were subsequently annealed. Bardenheuer and Schmidt4 found that the conductivity of copper was decreased by 3 to 4 per cent when reduced 50 per cent by working. The conductivity of 72-28

Jan 1, 1941