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By Stuart S. Forbes

Changes and additions made to the Canadian Copper Refiners Ltd. electrolytic refinery between 1949 and 1955 are reviewed. The effect of high current density on current efficiency and section work is discussed. OPERATING and physical changes which have been made to the electrolytic tank house of Canadian Copper Refiners Ltd. suggest a review of present conditions. Previous papers1 a have described the general arrangement. Since then, expansion, closer anode spacing, and higher current densities have increased annual cathode capacity from 112,000 to 182,000 tons. A recent extension to the tank house, begun in the spring of 1954 and completed in August 1955, was undertaken to handle the monthly production of about 3,000 tons of anodes from Gasp6 Copper Mines. The anticipation of these additional receipts and large stocks of unrefined copper caused by the increase in custom smelting at Noranda made it necessary to increase production without immediately available additional cell capacity. Accordingly, from December 1954 through March 1955, the tank house was operated successfully at a current density of 24.0 amp per sq ft. Again, as of September 1955, one of the two tank house circuits is being operated at this high density. Although other refineries may operate at current densities higher than 24 amp per sq ft, none is doing so with anodes which contain silver and gold content as high as those being refined at Canadian Copper Refiners Ltd. General Arrangement The original building consisted of two parallel bays, each 660 ft long and 60 ft wide, with a 24 ft pump bay extending along the west side of the building. A previous expansion, completed in 1939, was to the west of the original building and consisted of two 60 ft parallel bays 240 ft long. The length of these two bays was extended in 1954 to 540 ft, adding one stripper and 12 commercial sections to No. 2 electrical circuit. Space is still available for an additional six commercial sections and one stripper section. Construction on these seven sections started in September 1955, and will be completed early in 1956. The tank house capacity will then be 206,000 tons of cathodes per year. In the two tank houses there is a total of 900 cells distributed as follows—commercial, 468; stripper, 36; total, 504 in the No. 1 tank house (No. 1 circuit): commercial, 360; stripper, 36; total, 396 in the No. 2 tank house (No. 2 circuit). Section arrangement consists of nine cells to a tier and two tiers or 18 cells to a section. Anodes, weighing 620 lb each, are cast with a Baltimore groove and are refined by the multiple system. Solution enters each cell through a bottom inlet at one end and overflows at the top of the opposite end. Rate of solution flow through the cells is controlled by valves at each section to 4.5 gpm. Electrical power to the tank house is now provided by nine 675 kw motor generator sets. Each set consists of a 135-12 v 5000 amp dc generator, driven by a 980 hp 2300 v synchronous motor. When No. 1 circuit is operated at 22,000 amp, five sets, at 4400 amp each, are connected in parallel. As the maximum allowable current on No. 2 electrical circuit has recently been set at 18,000 amp, only four sets are connected in parallel on No. 2 circuit. A tenth set, now being installed, will be reserved as a spare, for use in either circuit as required. Recent Changes In 1949, the annual capacity of the tank house was increased from 112,000 to 132,000 tons by closing the

Jan 1, 1957

By George S. Koch

Since 1882, world zinc production has increased. In contrast, US zinc production rose until about 1915, but since then has remained nearly constant, with a slight tendency to decrease. Production from the Tri-State district, the largest early source of zinc in the US, has gone down steadily; this decline has been balanced by a growth in the rate of other districts. These changes in US production are due to economic, not geological, factors. Recent exploration has located large minable ore bodies: additional deposits will undoubtedly be found in the stratabound carbonate rock and volcanogenic environments. A statistical analysis of the exploration effort in the Middle Tennessee district indicates that new discoveries can be expected there. Thus, the US is in an early stage of the production cycle for zinc. Of major mining districts in the US, only the Tri-State is exhausted under current economic conditions; large zinc resources of low-grade material, which would repay mining at higher prices or improved technology, are known to exist in that district .

Jan 1, 1982

By Robert Isaac Williams

The Questa mine is located in northern New Mexico on the western flank of the Sangre de Cristo Mountains about 75 miles north of Santa Fe and ranges in elevation from 6,800 to 10,000 ft. GEOLOGY The rocks of the area are Precambrian metamorphic rocks covered by Tertiary extrusive andesites and rhyolites and intruded by Tertiary granitic rocks. These Tertiary intrusives are localized in an east-west belt about 20 miles long and 2 miles wide, extending from Questa to Red River. The Questa orebody is associated with a north-trending aplite intrusive about 3/4 mile wide and 1 3/4 miles long. In the area of mineralization, the metasomatism of aplite has produced a mottled porphyritic rock. This hybrid rock has caused much of the controversy about the Questa mine intrusive. The orebody is essentially monomineralic and consists of numerous closely spaced molybdenite veins varying in thickness from ' 'paint" to 3 in. and occurring in both the andesites and the intrusive. In the intrusive the veins are often siliceous. Common alteration minerals associated with the molybdenite ore vary with the original composition of the rock. The alteration of the aplite has produced phenocrysts of orthoclase, albite, oligoclase and biotite; veins of quartz, orthoclase, and biotite; and graphic myrmekitic intergrowths of feldspars and quartz. In many places near the contact, the andesite is indistinguishable from the metasomatized aplite. The dominant alteration in andesite, however, is the development of fine-grained biotite with apatite, rutile, and sphene.

Jan 1, 1969

By Russell Dayton

THE metallurgical polarization microscope has been utilized in several researches in the last few years, thus attaining a fair degree of prominence, but little has been written in a manner suitable to a metallurgist concern-ing the theory of this instrument. In this investigation the theory was carefully studied, and the results are presented here in a detailed manner, yet as simply as possible. The theory is discussed with particular reference to the three chief functions of the instrument: (1) determination of anisotropy; (2) effect of strain; and (3) identification of inclusions. Each of these is investigated experimentally, with especial attention to the mechanism of producing any effect. Where possible, the discussion is supplemented by photomicrographs. The instrument used had numerous defects as a polarization microscope; these and their remedies are discussed. In the microscopic study of transparent mineral sections (chal-cography) the use of polarized light has aided tremendously in the identification of a mineral. The determination of strain in transparent substances (photoelasticity) by the use of polarized light has lately become a commercial process, used in testing finished glass articles. The success of the use of polarized light with opaque materials has not been so great. The magnitude of the effects obtained is much less than that of the corresponding effects with transparent materials, and the mechanical difficulties are much greater. Konigsberger,(1)? in 1909, was the first to apply polarized light to the microscopic study of

Jan 1, 1935

By W. E. Ruder

IT has been pointed out by Stead 1 that grains of considerable coarseness may be developed in steels containing from 3 to 5 per cent. of silicon, and in a previous paper 2 the present author has shown that under the proper conditions of annealing single grains having an area of 50 sq. cm. may be obtained. It is the purpose of this paper to discuss in more detail the conditions, promoting the growth of these grains, in the hope that the experiments described may throw some additional light upon the general problem of grain growth in metals. These silicon steels lend themselves particularly well to such experiments because of the ease with which the change in structure may be followed and because of the fact that the effect of the carbon present is largely obliterated by the high percentage of silicon. This forms a solid solution with the iron, which acts very much like a pure metal. This alloy has been found to have but one critical point, viz., Are. This point, determined by Roberts-Austen for Hadfield's 4 per cent. Si alloy, was found to lie at 703° C. Vigouroux3, in working with pure Fe-Si alloys, finds this point to rise from 750° C. for 0.5 per cent. Si to 860° for 6 per cent alloy, with a flat region in the curve from 3 to 4 per cent. Si. No accurate determination of this point has been undertaken by the present author, but it has been roughly determined to lie between 730° and 750°.

Jan 12, 1913

By W. A. Backofen, D. H. Avery, G. A. Miller

An evaluation has been made of the relative importance of yield strength (?) and stacking-fault energy (y) to the rate of fatigue-crack growth in materials of fcc structure. Pure copper and its solid-solution al-loys with aluminum and nickel were chosen for the study because they provided sufficient range in both quantities of interest that either could be varied independently of the other. Experiments involved alternating tension and compression of flat specimens which were prepared with sharpened internal notches so that most, if not all, of the crack-nucleation interval could be eliminated. Growth rate (dC/dN) was concluded to be proportional to the square of the plastic-strain amplitude (€,,) over a strain range of approximately 6x 10-4 to 6 x 10-3. The factor, k, linking dC/dN and ep in dC/dN = kEp2 increased and decreased with corresponding variations in y, but it did not respond syste?>/atically to change in ay, indicating that y is the significant variable in crack growth at constant plastic-strain amplitude. In polycrystalline material, k varied by a factor of 5 over the available range of y. In a few single-crystal experiments on Cu-A1 alloys the growth rate responded less strongly to change in y. It has been suggested that single crystals behave somewhat differently than poly crystalline material because there is more extetnsive substructure near the grain boundaries in the latter, and this facilitates crack advance by separation along subgrain boundaries. A point of some controversy in current work on fatigue relates to the effects of strength and stacking-fault energy on crack growth. In recent experiments a separation was made between the cycling intervals for crack nucleation and the subsequent growth that eventually ends a specimen's fatigue life.' The study was carried out on Cu-A1 alloys primarily, fatigued in alternating four-point bending to constant deflection. A nucleation interval of about 10' cycles (at a total strain amplitude = 0.2 pct) was found to be insensitive to aluminum content in the range 0 to 7.5 wt pct, while the growth period was increased approximately forty fold over the same compositional range. The increase was not in any sense linear, however. Rather, most of the change occurred below 4 pct A1 or a stacking-fault energy, ?, of about 15 ergs per sq cm. It was argued that the plastic-strain amplitude was approximately constant, and therefore the effect of composition must have grown out of the reduction in stacking-fault energy. Several studies have shown that, with high ?, cross slip is encouraged, subgrain structure is introduced during fatigue, and cracking is aided through propagation along subgrain boundaries.1-5 Therefore, lowering ? sufficiently to interfere with substructure formation would be expected to retard growth rate. On the other hand, it is a general rule that resistance to fatigue cracking increases as strength is raised. Accordingly, there might still have been some doubt that Y was the controlling variable, since strength would be increased as y was lowered by the aluminum additions. To help in dispelling that doubt, an experiment was made on a polycrystalline Cu-Ni alloy similar in strength to the Cu-A1 alloys but of higher ?; the crack-growth interval was found to be essentially that of pure copper.' Further support for this position on stacking-fault energy as it relates to crack growth is derived from work by Boettner and McEvily,6 in which the actual crack-growth rate was measured on samples previously notched so as to minimize the nucleation period. Unfortunately, it was necessary in isolating strength level to compare different alloy systems and grain sizes. Recognizing the complication, it was still concluded that growth may be retarded by a reduction in y, per se. A related study has also been made by Roberson and Grosskreutz.7 The zinc content of a brass was systematically changed to alter strength and stack-ing-fault energy, although not below the 15 ergs per sq cm at which pronounced change in growth interval was found in the earlier work. The results were limited to more or less conventional S-N diagrams so that nucleation and growth events could not be separated. No definite conclusions were drawn, but

Jan 1, 1967

By W. H. Herrnstein, J. B. Clark, E. C. Utley, A. J. McEvily

The ratio of the endurance limit (10' cycles) to tensile strength of age-hardened aluminum alloys is approximately 0.3, whereas the ratio for annealed alloys is about 0.5. The lower value for the age-hardened alloys has been associated with the instability of coherent precipitate during cyclic loading, but it has not been definitely established whether this instability is due to overaging or reversion during cyclic loading. The results of the present investigatzon support the reversion viewpoint. In this work specimem of 2024-T4 aluminum alloy were aged for 16 hr at 150°C after cycling for 10 pct of the life at 25.000 psi. These specimens were then tested to failure and exhibzted a marked increase in fatigue life. It is proposed that during the early stages of fatigue in this alloy dislocations cut through the coherent precipitate and bring about the reversion of the precipitate. Subsequent aging at 150ºC induces reprecipitation in the precipitate-free zones so that the weakened regions are strengthened and the fatigue life is extended. It Is recognized that the fatigue strengths of precipitation hardened aluminum alloys are unusually low relative to their tensile strength.'-= This feature is illustrated in Fig. 1 where it can be seen that age-hardened alloys have lower fatigue ratios (the ratio of the fatigue strength to the tensile strength) than those in the annealed or cold worked state. Further, as shown in Fig. 2, the more an alloy is dependent upon precipitation hardening for its total strength, the lower is the ratio of the fatigue strength to the tensile strength. This state of affairs has been associated with an instability of the metastable metallurgical structure of precipitation hardened aluminum alloys during cyclic loading. Evidence2 in support of this view is that the fatigue ratio increases in these alloys as the test temperature is lowered, thereby indicating that thermo-mechanical instability, rather than some other factor such as a non-uniform distribution of precipitate, is the factor responsible for the low fatigue ratio at room temperature. Two mutually exclusive proposals have been ad- vanced to account for this instability. Hanstock has proposed that overaging takes place during cyclic loading, and in support of this view, Broom et a1.2 have indicated that an overaging process might be promoted by the large numbers of vacancies which are created during cyclic loading. The creation of vacancies by radiation4 has been shown to lead to rapid overaging. Hanstockl obtained visual evidence of overaging in an aluminum alloy after cyclic loading, but in this instance it has been pointed ou? that because of the high frequency used (60,000 cpm) the observed effect may have been due to normal high temperature precipitation around energy dissipating cracks. Efforts to discern visual evidence of overaging in this alloy at lower test frequencies were not successful.3 The alternative postulate3 is that reversion takes place during cyclic loading and leads to localized soft spots at which fatigue cracks are readily initiated. Evidence for this process has recently been provided by Polmear and Bainbridge5 who demonstrated metallographically that regions depleted of precipitate were created during cyclic loading of an aluminum alloy. Inasmuch as precipitate particles bordering the depleted region had not grown in size, it was concluded that the solute atoms which had constituted the missing particles had gone back into solution. No mechanism for the reversion process was presented. The present study was undertaken to investigate further the conditions leading to instability during cyclic loading, and to determine whether reversion or overaging had taken place as a result of cyclic loading. BACKGROUND AND TEST PROCEDURE In order to differentiate between the processes of reversion and overaging, rest periods at an elevated temperature, which ordinarily would insure additional precipitation, were used in this investigation. It was expected that after a period of cyclic loading an elevated temperature rest period would result in a decrease in the remaining life of the specimen if overaging were occurring during cyclic loading, whereas in the case of reversion, reprecipitation would occur and the fatigue life would be extended. Such an expectation is based on the assumption that the crack-nucleation phase is a significant portion of the total fatigue life, and that such a treatment is of influence in the crack-nucleation stage and is relatively unimportant thereafter.

Jan 1, 1963

By F. W. Jessen, James N. Howell

The accumulation of paraffin deposits in tubular goods has been recognized as a major production problem since the inception of the petroleum industry. This problem is not limited to any particular geographical area nor is it limited to a specific type of crude oil.' Generally speaking, "paraffin" deposition pertains to the deposition of any predominately organic material in flow lines, and possibly even at the sand face, which would hamper the production of oil. In some fields, a continuous effort is required to remove deposits of paraffin and in order to accomplish this, many unique methods have been devised. The best solution to this problem, however, is to prevent the formation of such deposits. One method which has been tried in a number of fields is the use of plastic pipe. The purpose of this investigation is to compare the relative effectiveness of several plastic materials to aid in the reduction or prevention of paraffin accumulations in surface flow lines. COMPOSITlON OF PARAFFIN DEPOSITS By definition, paraffin deposits are those materials which are insoluble in crude oil at the prevailing producing conditions of temperature and pressure. Such deposits1 s usually consist of small particles of petroleum wax intermixed with resins, asphaltic material, and crude oil. They may also contain a variety of foreign materials such as sand, silt, water, various metal oxides, sulfates and carbonates of iron. barium, and calcium. The petroleum waxes deposited in flow strings usually consist of both a "hard" and a "soft" wax fraction. These waxes are largely aliphatic hydrocarbons with smaller amounts of aromatic and naphthenic compounds. Nathan' has classified the hard and soft wax fractions. The aliphatic hydrocarbons present are those of high molecular weight with high melting points. Reistle3 pointed out that these high molecular weight compounds first separate from the oil due to a sharp decrease in solubility as the melting point increases. The identification of the resins and asphaltic materials rests, at present, on an arbitrary solubility procedure. Under certain conditions, materials which are insoluble in pentane (ASTM D-893) are defined as resins and asphalts. Subgrouping of these materials is made on decreasing solubility in benzene and carbon disul-fide. Shock' found some correlation be-tween the solvent response and the pentane insoluble content of paraftins: higher pentane insoluble fractions are less soluble in any of the commonly used commercial solvents. PARAFFIN CONTROL METHODS The methods used in oil fields to prevent and remove paraffin accumulations can be grouped into four general classes: (1) operative methods, (2) physical methods, (3) chemical methods, and (4) combination of any of these. Operative methods attempt to prevent the formation of paraffin deposits while the other methods are concerned primarily with the removal of these deposits. Plastic coated pipe has been used for a number of years to prevent cor- rosion in wells, and in manv instances paraffin deposits have -been greatly reduced. Field observations have indicated that plastic coated pipe not only reduced paraffin accumulation but in some cases eliminated deposition completely; however, data are needed to demonstrate the relative effectiveness of plastic materials. Deposition Apparatus The pipe used to determine the effect of velocity on rates of deposition was %- and 2-in. nominal diameter, and 5 ft in length. Steel, butyrate, rigid PVC, kralastic resin-type plastic pipes, epoxy coated pipe, PVC lined glass fiber pipe, and aluminum pipe were tested. Steel pipe was used as a control. Fig. 1 is a schematic diagram of the apparatus showing the relative position of the separate units making up the equipment. In order to facilitate the installation and removal of the test pipes in the apparatus, O-ring seals capable of sustaining pressures of 50 psi were provided at each end. Test pipes were submerged in a cold water bath maintained at or below room temperature by circulating water through copper cooling coils packed in ice. A hot water bath equipped with immersion-type heaters, stirrers, and a thermoregulator was used to maintain the temperature of the oil prior to introduction into the piping manifold. The capacity of the oil reservoir was 30 gal. A 33-gal/min centrifugal pump, capable of producing turbulent flow velocities in the test pipes, was used to circulate the oil through the system when using %-in. pipe; and a 70-galjmin centrifugal pump was used in later tests using 2-in. pipe. A by-pass arrangement made it pos-

By Dr. O’Neil Thomas J., Donald W. Gentry

The greatest of all gifts is the power to estimate things at their true worth. LaRockefoucauld INTRODUCTION The primary reason for performing a feasibility study on a proposed mining venture is to investigate all phases of the proposal in as much detail as necessary to justify either dropping the project or continuing expenditures through the next stage. The economic evaluation component of the feasibility study, therefore, must ultimately be based on information which provides an answer to the question, "What is it going to cost?" Unfortunately engineers preparing feasibility studies never have all the engineering or economic information they would like or need. Consequently, the economic portion of the analysis can only be performed if estimates of the various costs associated with the project are made. Project cost estimates, in turn, require estimates of all the physical factors affecting cost components, including anticipated performance of plant and equipment as well as all pertinent geologic, mineralogic, and metallurgical variables. Before useful cost estimating procedures can be applied considerable data must be collected, compiled, and organized. Preparatory work typically includes organization of cost data available for estimating purposes, development of techniques for updating historical costs, and establishing methods of forecasting prices and costs over the duration of the project. Cost estimates for mining and mineral processing projects involve so many features and variables that it is absolutely essential to have some means by which the vast amount of detail can be organized. It is very important to identify, in as much detail as possible, all the cost data available (historical and developed) to the estimator. These costs, after being properly identified in detail, should be com- piled, stored, updated regularly, and made readily available for use in developing new cost estimates Accessing files of current cost information requires a standardized numerical system of classifying cost data. When uniform definitions and procedures are used, every project record contributes to the common store of estimating data.

Jan 1, 1984

By F. M. Simonds, E. Z. Burns

The Rawley property is located in the Kerber Creek mining-district, Saguache county, Colorado, at an elevation of 10,600 ft. (See sketch-map, Fig. 1.) Ore was found in this vicinity as early as 1880, and claims covering a large area were located and in many instances patented. The ores, however, being of comparatively low grade, and the nearest railway station, Villa Grove, being some 20 miles away, it is extremely doubtful whether any considerable amount of ore was ever handled at a profit. It is safe to say that several hundred thousand dollars were spent (a large part in building mills) previous to 1902-03. About that time a very capable promoter gathered together a group of these claims and interested some New York people, who had had no previous mining experience, in the purchase of these claims. Following the organization of a company, this promoter became General Manager. As often happens under such conditions, the first step was to erect a mill to treat 100 tons per day. It may not be fair to this enterprise to say that the failure which followed might have been foretold, simply on general principles, but this much is certain—the water supply fluctuates in the course of a season through a wide range and for a considerable portion of the year was inadequate to run this mill at capacity. Further, it is currently reported that some of the mill foundations were placed on ice. However true this statement may be, it is a fact that, when first inspected by us, many of the belts in the mill were held on'their pulleys by means of idlers. A shut-down followed, with a material re-adjustment of interests, at which time we became consulting engineers for the company.

Jan 1, 1914

By W. P. Sykes

SEVEN years ago, Dr. S. L. Hoyt1 presented a masterful discussion of the hard metal carbides and cemented tungsten carbide. His lecture summarized most of the data then available in the field; many of the details relating to the production, properties and structure of cemented tungsten carbide had never been previously published, for, in fact, this information was only then being acquired. During the intervening years, the cemented carbides have assumed a place of real importance in the commercial field, with an ever widening variety of applications due to constant improvement in the control of production technique and the unremitting search for new compositions that might better the performance of the alloys in one or another type of service. The most recent summary of production methods, properties and guides for the successful application of the cemented carbides appears in the 1936 edition of the Metals Handbook. Of necessity, much detailed information relating to structures and physical properties is not included in such a summary, and it is with such details that the present discussion is concerned.

Jan 1, 1938

By Donald C. Barton

The theory of gravitation is based on Newton's law that any two bodies exert a mutual attraction which is proportional to the product of their masses and inversely proportional to the square of the distance between them; i. e., A = KMRm2 (1) where K is a constant, M and m are the respective masses of the two bodies, and R the distance between them. In the earth's gravitational system, the earth is one of the bodies; the other may be any body within or without the earth. In theoretical discussions and calculations,in regard to gravity, that other body usually is taken as a unit of mass: in the C:. C:. S. system, a body of one gram in mass. Gravity and Level Surfaces Gravity is defined in geophysics as the force of attraction exerted by the earth, towards itself, on a body of unit mass. The intensity of gravity is usually expressed in dynes of force or in centimeters of acceleration In geophysical work in America, most commonly it is expressed in dynes (per gram) with the "per gram" understood and not directly expressed. In geophysical work in Europe, most commonly it is expressed in centimeters per second per second (cm. /sec.2) and less commonly lrierely as centimeter-gram-second units (c. g. s). At sea level, the intensity of gravity amounts very nearly to 980 dynes. The vertical is the direction along which the attraction of gravity is exerted at any point. In most cases, it is very nearly, but not quite, perpendicular to the earth's surface. The path that would be taken by a body falling freely through space toward the earth is vertical at each point and may be spoken of also as ('the vertical," or as the line of the vertical, or as a line of force of gravity. At the earth's surface it comrrlonly is very nearly, but not quite, a straight line.

Jan 1, 1929

A1 in carbon steel, equilibrium temperature, XLVII, 740-747. A2 and A3 in pure iron, critical ranges, XLVII, 665-739. Abbott, Ai Arthur: [biog. notice, Bulletin No. 27, Mar., 1909, xxvii]; death, XXXIX, . [xl]. Abbott, Arthur Vaughan: [biog. notice, Bulletin No. 16, July, 1907, 6581; death, XXXVII, [xxxix]. [ ]

Jan 1, 1918

By Cyril Smith

ISOLATED alloys of copper and silicon were prepared and examined by chemical methods more than one hundred years ago, but it was not until the work of Rudolfi1 that the equilibrium relations. were studied. The early history of the alloys was well described by Baraduc-Muller2 PERCENT SILICON-BY WEIGHT FIG. 1.-COPPER-SILICON EQUILIBRIUM DIAGRAM ACCORDING TO RUDOLFI (1907). and need not be further discussed here. The diagram of Rudolfi, based entirely on thermal observations, showed silicon to be soluble in copper up to 4.5 per cent. at 849° C., at which temperature there was a peritectic horizontal resulting from the formation of a 0 phase with about 7.4 per cent. silicon from a and liquid with 7.85 per cent. silicon. The ß phase was believed to form a eutectic with Cu3Si at 820° C. and 9.8 per

Jan 1, 1928

By A. L. Jr. Pozzi, A. O. Garder, D. W. Peaceman

A new numerical method is proposed for the solution of multidimensional miscible displacement problems. Besides the usual stationary grid associated with numerical procedures, the method uses moving points for which positions and concentrations are computed each time step. Based on the method of characteristics for treating combined transport and dispersion, the method applies equally well to any number of dimensions and, in contrast with other numerical procedures, properly takes into account the physical dispersion, no matter how small. Extensive tests show that accurate solutions of one-dimensional problems can be obtained over a wide range of values of the dispersion coefficient, including zero. They also show that the moving points do not need to be uniformly spaced, and that increasing the number of moving points beyond 2/grid interval does not significantly improve the accuracy of the solution. Two-dimmsional calculations using the new method were carried out to simulate laboratory model displacements in which gravity caused overriding of solvent. Good agreement between observed and computed profiles and measured and computed concentrations of produced fluid was obtained for a viscosity ratio of 1.89; at higher viscosity ratios, fair agreement was obtained Computed results were found to be significantly affected by vertical dispersion, and negligibly affected by dispersion in the direction of flow, in agreement with conclusions based on experimental observations. INTRODUCTION Although miscible displacement processes are potentially of great economic significance, limited progress has been made in developing mathematical methods for predicting the outcome of a solvent flood. Because of the complexity of the partial differential equations which describe multidimensional miscible displacement, numerical methods are a natural approach to their solution. The task of finding suitable numerical approximations to one of the partial differential equations, which involves both dispersion and convective transport, has been particularly difficult. Dispersion in the absence of transport is described by the heat flow equation, a second-order equation of parabolic type. This equation has been very successfully treated by numerical methods. Transport in the absence of dispersion is described by a first-order equation of hyperbolic type. This equation has been treated numerically with some success in one dimension, both by Lagrangian and Eulerian techniques, 1.2 but extension to two or more dimensions has not been satisfactorily accomplished. Usually one of two things happens: either the numerical solution develops oscillations or it becomes smeared by artificial dispersion resulting from the numerical process. When transport and dispersion are considered simultaneously, this numerical dispersion may dominate the low physical dispersivicy that generally characterizes miscible displacement. Stone and Brian2 have developed a new difference equation for treating combined transport and dispersion in one dimension. By suitable choice of certain parameters, they succeeded in markedly reducing both oscillation and numerical dispersion. However, a satisfactory extension to higher dimensions has not yet been found. Peaceman and Rachford3 presented a centered-in-time and centered-in-distance difference equation combined with a 1,transfer of overshoot" procedure which was demonstrated to work well in one dimension. The technique was applied to the two-dimensional miscible displacement problem, but subsequent calculations with zero dispersivity showed little change in results compared with the calculations they presented. This indicates that their method involved a numerical dispersion of the same order as the physical dispersion. The present paper describes an alternate method for solving the combined transport-dispersion

Jan 1, 1965

Jan 1, 1902

By Archer E. Wheeler, Milo W. Krejci

The Boston & Montana Reduction Works at Great Falls, Mont., was formerly the reduction works of the Boston & Montana Consolidated Copper & Silver Mining Co., and continued as the reduction plant for the independent company until June 1, 1910, when the consolidation of a large number of the operating companies of Butte was effected. It then became merged in the Anaconda Copper Mining Co. as the Boston & Montana Reduction Department of the Anaconda Copper Mining Co. The history of copper converting at this plant, while not covering the entire period of the commercial use of the process in this country, does cover by far the larger part of it, and as the operation of and appliances for the process have undergone many changes during the time, it may, perhaps, be of some interest to put the record of these changes into permanent form. The plan followed in the preparation of this paper has been to give first a brief chronological record of the principal events and changes and then, even at the risk of some repetitions, to give more detaild accounts of some of these changes under separate headings. The headings for the complete paper are as follows: 1. General. Chronological Review. 10. Development of Different Classes 2. Mechanical Manipulation. of Converters After Class I. 3. Casting of Finished Copper. 11. Basic Lining. 4. Tamping of Linings. 12. Number and Size of Tuyeres. 5. Early Acid Linings. 13. Cast Copper Tuyeres. 6. Acid Linings With the Use of Ore. 14. Efficiency of Air. 7. Introduction of Flux Through the 15. Size of Converter Mouth. Tuyeres. 16. Height of Converter. 8. Bottom Blast. 17. Summary. 9. Disposal of Converter Slag, General Chronological Review. Ground was broken for the general concentrating and smelting plant in the spring of 1,891. The first departments to start operations were the concentrator in March, 1892, and the Brückner roasting and reverbera-tory smelting departments in April, 1892. The converter department

Jan 1, 1914

By R. D. Schoone, J. T. Michalak

Recovery, recrystallization, and texture development of a cold-rolled aluminum-killed steel have been studied during simulated box annealing. Two different initial conditions existed prior to cold rolling: 1) essentially all of the nitrogen in solid solution and 2) most of the nitrogen precipitated as AlN. The combined effect of nitrogen and aluminum in solid solution before annealing was to inhibit recovery and sub-grain growth at temperatures above about 1000°F and to raise the recrystallization temperature range on continuous heating at 40°F per hr from 1000"-1050°F to 1065"-1085°F. For the material with nitrogen and aluminum initially in solution there was an inhibition in the nucleation of the (001) [110] texture component and an enhancement of the (111) [110] texture component. The differences in annealing behavior mzd texture development are attributed to preprecipitation clustering of aluminum and nitrogen at subboundary sites developed by prior cold working. THE annealing of cold-worked aluminum-killed steels has been the subject of numerous investigations.'-'2 These studies have been concerned with kinetics of recrystallization, with microstructure and texture development, and with the individual and combined effects of composition, thermal history prior to cold rolling, and heating rates during subsequent annealing. It has been shown that the inhibition of recrystallization, and the development of the pancake-shaped grain and recrystallization texture characteristic of aluminum-killed steels, can be associated with the precipitation of A1N particles during a recrystallization anneal involving heating rates in the range 20" to 80°F per hr. If the AIN is precipitated before cold rolling or if more rapid heating rates are employed, the cold-rolled steels recrystallize more rapidly to an equiaxed grain structure and texture comparable to that of rimmed low-carbon steel. The retardation of recrystallization, the development of the elongated grain structure, and the pronounced (111) texture have been attributed to: 1) precipitation of A1N at prior cold-worked grain boundaries to form a mechanical barrier to grain boundary migration;' 2) precipitation on the boundaries of the growing recrystal-lizing grains as well as on cold-worked grain boundaries;'" and 3) preprecipitation clustering or precipitation on subboundaries to retard recovery, nucleation, and growth. The present study was undertaken to study in more detail recrystallization and texture development during commercial box annealing of cold-rolled aluminum-killed steels. Comparison of the annealing be- havior after cold rolling, for two different conditions prior to cold rolling, was made in an attempt to define more clearly the role of aluminum and nitrogen in forming the recrystallization texture. A) MATERIAL AND PROCEDURE The material used in this investigation was a commercial low-carbon aluminum-killed steel which was hot-rolled with a finishing temperature of about 1565"F, then coiled at about 1020°F. The composition, in wt pct, was: 0.050 C, 0.30 Mn, 0.007 P, 0.019 Si, 0.03 Cu, 0.02 Ni, 0.02 Cr, 0.045 Al, and 0.004 N. Two 4.5 by 13 by 0.078 in. sections were cut from the center section of a hot-rolled panel and one of these was reheated to provide two different conditions prior to cold rolling: low AlN: as commercially hot-rolled, with aluminum and nitrogen in solid solution; and high AlN: as commercially hot-rolled, then reheated at 1300°F for 3.5 hr to precipitate most of the nitrogen as AlN. ~etallc&a~hic examination indicated that the reheating did not change grain size nor carbide distribution (some spheroidization of pearlite was noted). Texture analysis at half-thickness level showed that both sections had the same substantially random as-hot-rolled texture. The results of check chemical analysis of each sample are given in Table I. Both sections were cold-reduced 65 pct on a laboratory rolling mill to a final thickness of 0.027 in. Cold rolling, in one direction only, was in the direction of the prior hot rolling. Specimens 1.0 by 1.25 in. were cut from the cold-rolled sheets and given a simulated box anneal in an atmosphere of 2 pct HZ-98 pct He. Specimens were heated at a constant rate of 40°F per hr from room temperature to various temperatures in the range 750" to 1300°F and cooled immediately by withdrawal to the water-cooled end of a tube furnace. The temperature in the 6-in. uniform hot zone of the furnace was controlled within 3"F. Selection of the individual specimens was made to give a random distribution of annealing temperatures with respect to location in the cold-rolled sheet. At least two specimens of each condition were annealed to the same temperature and smaller specimens for light microscopy, transmission electron microscopy, and X-ray studies were prepared from each of these. Rolling-plane sections for each of these studies were taken at half thickness. Light microscopy and transmission electron micro-

Jan 1, 1969

By R. D. Carnahan, J. E. White

A study of dispersion strengthening in TD-Nickel (nickel plus 2 vol pct Tho2) was conducted employing microstrain techniques at ambient room temperature. It was found that optimum strength was due primarily to the incorporation of stored energy developed by a variety of thermal-mechanical treatments. The relatively low strength of the recrys-tallized condition implies that the dispersed particles themselves offer only token resistance to deformation. The development of resistance to large-scale recovery or recrystallization at temperatures near the melting point requires a more extensive sequence of strain-anneal cycles than does the development of optimum strength. A micro-Bauschinger effect was observed which appears to be related to the lattice resistance to the movement of free dislocations. The effect was nearly identical to that in pure nickel indicating that the presence of the dispersed phase and considerably increased dislocation density (stored energy) only alters the number or effectiveness of barriers. THE early stages of deformation of engineering materials can be conveniently studied by utilizing strain-gage techniques which permit resolution of strains less than 5 X 10-7 in. per in. for testing in four-point bending (Carnahan and white1). The present investigation, part of a continuing study on the very early stages of deformation, was designed to reveal the true role of a dispersed phase in promoting high strength in a commercially available dispersion-strengthened alloy. Although this technique has been used for some time to study microdeformation in pure metals and alloys, it has just recently received attention as a means of investigating dispersion strengthening. Studying the very early stages of deformation in alloys which depend upon a finely dispersed inert phase for strength may prove to be a very important method for a better understanding of these materials. It is essential to obtain considerable clarification of actual dislocation movement and the kinds of deformation barriers which exist before optimum properties can be designed into this type of material with any degree of confidence. Considerable research on a variety of dispersion-strengthened materials has resulted in two different schools of thought regarding the strengthening mechanism. One faction2-4 favors the idea that the particles themselves resist the motion of dislocations. The criterion for yielding is the fracture of the dispersed second-phase particles due to an array of piled-up dislocations. Other invesfigators5-a have shown that particles are effective primarily by allowing a greater buildup of stored energy or dislocation density through thermal-mechanical treatments in the composite than the pure matrix material. The particles themselves, then, are not exclusive obstacles, but the complex network of particles, dislocation tangles, subboundaries, and grain boundaries are strength determining. The development of such a complex dislocation network in SAP has been studied recently in some detail by Goodrich and Ansell. The ability of dispersion-strengthened alloys to resist softening or recrystallization is also of considerable importance; however, the criteria for maximum stability may not necessarily be those for maximum strength. In this study, in addition to the evaluation of the microstrain properties of TD-Nickel, it is felt that considerable clarification of the true dependence of strength and stability on the dispersed phase is shown. I) MATERIAL AND PROCEDURE TD-Nickel is a dispersion-strengthened alloy developed by the E. I. DuPont de Nemours Co., which contains 2 vol pct thoria (Tho2) in a pure-nickel matrix. The average ThO2 particle size is approximately 0.1 p and the interparticle spacing is less than 1 u. The material was supplied by DuPont in two conditions: hot-extruded bar stock, and stress-relieved cold-rolled sheet 0.025 in. in thickness. The bar was extruded at 2200°F from a cold-pressed and sintered billet. The sheet stock was prepared from the extruded material by a process involving ten or more 50-pct cold reductions by rolling with intermediate anneals at 1800° to 2000°F. Test specimens used in this study were prepared in the form of rectangular parallelepipeds measuring 0.375 by 1.375 in. in thicknesses ranging from 0.025 to 0.040 in. Samples prepared from sheet and extruded stock were mechanically polished before heat treatment and were handled with extreme

Jan 1, 1964

By R. S. Handy

DOES hand-sorting of mill feed pay? The fact that the practice is so general would seem to indicate that there must be good reasons for following it; yet, to my mind, the advantage in many cases is doubtful enough to invite a thorough discussion of the subject, in an effort to determine under what conditions hand-sorting does pay. A typical sorting plant in the Coeur d'Alene district handles about 800 tons of mine-run ore per day. The material is run over a grizzly with about 4-in. opening; the oversize is crushed to about 4-in. size and joins the undersize, and the whole product is washed and screened on trommels with about 1 ½ -in. openings. The oversize from these trommels is spread on a belt and the waste and first-class ore are sorted out by hand, the residue being further crushed, and passes, together with the trommel undersize, into the mill feed bins. About 50 tons of shipping ore and 150 tons of waste are sorted out per day, leaving about 600 tons of mill feed. To sort out this material requires 20 ore sorters and five bosses and repairmen. The normal cost of hand-sorting is about 16 c. per ton of run-of-mine ore, or 65 c. per ton of material sorted out. I believe that straight crushing and milling of the run-of-mine ore, in this case, is not only cheaper, but is metallurgically moree canonical and efficient than hand-sorting followed by milling of the residue. At one of the Bunker Hill rock-houses, 1250 tons of run-of-mine ore are reduced to pass 30-mm., or about 1 ¼ -in. opening in six hours, requiring five men. The equipment and the power consumed are not greatly different from that required in a sorting plant of the same capacity, and the normal cost of thus preparing the feed for milling is under 3 c. per ton of mine product. The relative cheapness of this method as against hand-sorting is thus clearly established, the saving being about 13 c. per ton. If there is any virtue in hand-sorting, then, it must lie in the metallurgical results achieved.

Jan 4, 1918