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By R. V. Norris

The removal of mine-water by hoisting in tanks instead of pumping, while somewhat a reversion to the methods of the ancients, has come very rapidly into favor in the anthracite region of Pennsylvania during the past few years. In fact, so much so, that at the present time there are at least eight large collieries at which all the water is hoisted, and six more plants are in preparation. The particulars of the plants in operation and under construction, as far as decided on, are given in the tables on pages 107 and 108. Besides these, the Delaware, Lackawanna and Western R.R. Co. is constructing a hoist of large capacity for a depth approximating 500 feet, to be located in the Keyser Valley, near Scranton. The hoists will be driven by electric motors, geared directly to the sheaves. The Lehigh Valley Coal Company is planning a large hoist for the Packer collieries in the Shenandoah district, but no work has been done on this as yet. The earliest regular hoisting, I believe, mas done by means of semi-cylindrical tanks (Fig. 1) at the Nanticoke collieries of the Susquehanna Coal Company. These tanks were attached under the regular shaft-carriages, taking in water through six large clack-valves in the bottom, and discharging through an endgate opened by a lever which was operated by a guide-piece on the shaft head-frame. These tanks were designed July, 1880, by the late J. H. Bowden, one of the very early members of the Institute. Similar tanks are still used in emergencies at the Nos. 1, 2, 3 and 6 shafts of the company. The objections to. their use were: that water could only be hoisted during the night-shift, or when the shafts were not in use for hoisting coal, thus requiring a very large sump, and greatly limiting the water capacity of the plants; that the alternate wetting and drying

Jan 1, 1904

By F. B. Foley

A description of tests made by a committee of the Division of Engineering of the National Research Council to determine whether velocity of impact affects the formation of Neumann bands. FOREWORD Not infrequently, in the case of the failure of a metal structure, such as a bridge, tank, airplane, gun carriage, etc., a doubt arises whether the failure was due, among other causes, to the effect of an overburden or of an explosive maliciously or accidentally exploded in contact with it. As few means of discriminating between the effects of these causes have been known and these means were of a rough qualitative character, it was surprising to find in the record of an inquiry into the failure of a structure, the statement that, by observations on the Neumann bands in the structure, it was possible to determine the speed of breakage in the metal and to distinguish between a fracture caused by an explosion and one caused by an ordinary mechanical strain. Such a criterion, if well proved, was of value to the explosives experts of the Bureau of Mines, the Ordnance Department of the United States Army and the Bureau of Ordnance of the United States Navy, but search showed no record of it in the literature nor did any of the metallurgists and metallographers consulted know of any data on which such a criterion could be based having been assembled and critically studied. However, it was universally held that there was promise in the idea and that there existed unique facilities at the Bureau of Mines Experiment Station at Pittsburgh for the preparation, under definitely known conditions, of material for study by metal-lographers, and that material of value might also be obtained from the proving grounds of the Army and Navy. Therefore, with the approval of the Director of the Bureau of Mines and the Chiefs of Ordnance of the War and Navy Departments, the Chairman of the Division of Engineering of the National Research Council, on April 12, 1919, appointed a Committee on the Investigation of Neumann Bands, which has since been engaged in this study and which, after some slight change in its personnel, consists now of the following: Dr. William Campbell, Advisory Metallurgist, Bureau of Ordnance, Navy Department. F. B. Foley, Metallurgist, Bureau of Mines. S P. Howell, Explosives Engineer, Bureau of Mines. Comdr. O. M. Hustvedt, U. S. N., Bureau of Ordnance, Navy Department. Dr. Charles E. Munroe, Chief Explosives Chemist, Bureau of Mines.

Jan 9, 1922

Book Notices CATALYSIS IN INDUSTRIAL CHEMISTRY. By G. G. Henderson. Lond. and N. Y., Longmans, Green and Co., 1919. 202 pp., cloth, 9 X 6 in., $3.25. This, the latest volume of the series of Monographs on Industrial Chemistry which is being published under the editorship of Sir Edward Thorpe, is intended to present broadly, our present knowledge of the phenomenon of which it treats. The hook reviews the existing literature on catalysis, paying particular attention to the many applications now used in industry. COMMERCIAL OILS-VEGETABLE AND ANIMAL. With special reference to Oriental Oils. By I. F. Laucks. 1st edition. N. Y., John Wiley and Sons, Inc.;, Lond. Chapman and Hall, Ltd., 1919. 138 pp., cloth, 8 X 5 in., $1.25. Intended to give to men in the oil trade, who have not had technical training, the technical data and information required in every-day dealings, in concise form. The various commercial oils are listed, together with their sources, uses, and phys-ical and chemical characteristics. The values have been collected from the standard texts, supplemented, particularly in regard to oriental oils, by the results obtained in the author's laboratory. FIFTY YEARS OF IRON AND STEEL. By Joseph G. Butler, Jr. Cleveland, The Penton Press, 1919. 145 pp., por., 10 X 6 in., leather. (Gift of author.) This volume is one of a special edition, of 100 copies, of an address delivered before the American Iron and Steel Institute in 1917, in which the author gives his personal reminiscences of the development in iron and steel making, as observed during an active participation in the industry in eastern Ohio, which began in 1857. To this are added some brief data on the early history of iron and steel, and a chapter on the activities of the American iron manufactures during the great war. The volume is profusely illustrated with portraits of men of note in the industry.

Jan 12, 1919

Illinois is rightly known as containing the coal deposit of which the first record in the United States was made. Joliet and Marquette saw "charbon de terre" along the Illinois River in 1673;1 LaSalle saw "mines de charbon" along the same stream in 1679; and Hennepin reported having "found in Several Places Some Pit-Coal" in 1682.2 In 1687 Jontel, in writing of the Illinois River country said, "along the river are coal pits, the coal whereof has been try'd and found very good."3 J. Carver reported the northern parts of the Mississippi River valley, "containing lead, copper, iron, coals, etc." in 17664 evidently referring to the Illinois country. Croghan, in the same year, saw coal along the Wabash River, near the mouth of the Vermilion in Indiana, but not far from Danville. Capt. Philip Pittman in his journey up the Mississippi in 1770 reported that "great pieces of coal are constantly found on the sand-banks, from whence it may be concluded, that there are coal-mines on the upper parts of the Mississipppi."5 This coal could only have come from the Illinois or Big Muddy Rivers. Morse, in 1798, refers to great quantities of coal on the upper branches of "the Father of Waters," and "on the Illinois River is a coal mine, which extends for half a mile along the middle of its banks."6 While, undoubtedly, some coal was used locally in various places, no records have been left of it and the first definite one is that in 1809 William Boon shipped some coal from the Big Muddy River, in Jackson County, to New Orleans, which was the first coal exported from Illinois.1 There has been considerable discussion as to this first shipment, whether it was made in 1809, 1810 or 1812. The records of arrivals of: boats in New Orleans in those early years is specific as to date, name of craft and name of captain, but no mention is made of cargo carried. William Boon arrived

Jan 1, 1942

By P. G. Shewman, T. L. Wilson

Using published surface-diffusion (D,) data and published sintering equations, it is shouln that surface difusion should dominate the neck-growth stage of intering for all materials in which D, has been measured (six metals and A1as). Also, grain boundary diffusion can be expected to contribute appreciably to shrinkage and possibly to neck growth below some critical temperature of the order of 70 pct 01- the absolute melting temperatuve. In view of the widespread conclusion in previous sintering work that volume diffusion dowzinates neck gvowth, experiments were conducted using spherical copper powders to test this conclusion. Scaling studies on neck growth at 950°and 1020°C clearly demonstrated that suyface diffusion dorninates. Kinetic studies on shrinkage gave more equivocal results that indicated an increasing role of' grain boundary transport at lower temperatures. Five diarszeters from 100 to 300 u were used in the scaling sludy and a temperature range of -650' 10 950 C was covered in the shrinkage studies. All experiments were conducted in dvy hydrogen. In 1949, Kuczynski published his now classic paper on the determination of the transport mechanism in sintering from the time laws of neck growth. In the interim, these laws have been applied to many systems and slightly modified by several authors. Essentially all these authors concluded that, for crystal- line materials, the dominant transport mechanism in neck growth is volume diffusion. This stems from the observation that the neck radius increases about as t"5 and that the activation energy approximates that for lattice diffusion. A related but independent series of studies stems from Mullins' rigorous analysis of the growth of the groove formed where a grain boundary meets a free surface." xperimental work stemming from this analysis has shown that for each crystalline material studied (Au, Ag, Cu, Ni, Fe, Pt, Al2O3) surface diffusion was clearly the dominant transport mechanism for groove widths up to the order 10 to 20 p. The ratio of the quantity of material being carried by lattice diffusion to that carried by surface diffusion increases linearly with the groove width, so surface diffusion is dominant for all widths under 10 to 20 u. The analysis of the relative contributions of surface and volume diffusion to grain boundary grooving, and to neck growth in sintering, shows that they are quite similar. Thus, using the available surface-diffusion data and the approximate equations of Kuczynski, or the more rigorous recent equations of Nichols and Mullins, 3 it can be shown that the small necks between particles must grow almost entirely by surface diffusion. The purpose of this study was to re-examine the basis for the conclusion that the neck-growth stage of sintering proceeds by volume diffusion. Using spherical copper powders, of several different diameters, precise experimental measurements were made of both neck growth and shrinkage. Application of Herring's scaling laws to the neck-growth data clearly indicated that neck growth occurred by surface transport, even though the neck radius increased as or Using the recent analysis of Mullins and Nichols as well as published data on surface diffusion, it is shown that the observed time law, as well as actual rate of neck growth, can be satisfactorily explained by a surface-diffusion mechanism.

Jan 1, 1967

By S. M. Marshall, A. C. Richardson, H. Y. Yancey

A year ago, Marshall and Bird presented a paper in which a new method of measuring the agglutinating power of coal was described.' The procedure used was to determine the strength of a button containing 10 parts sand and one part coal, formed by carbonizing the mixture in a crucible in an electric furnace. The result of the determination was reported as the total weight in grams required to bring about complete destruction of the button. Correlations were shown between the agglutinating value and some of the characteristics of the different coals that were investigated. This agglutinating test has been in use fairly continuously during the past five years for coals of widely differing coking qualities, and it has shown reasonably concordant results accurate enough for commercial use, although there are many features of the test which should have further scientific study. During the past year a study has been made of some coals of low coking strengths, and incidental to the main investigation some data which appear to be of interest and value were obtained on the loss in agglutinating power caused by exposure to the air. Three coals were investigated, all of which were of the Tertiary age; two were from one field in Asia, and one from a field in the United States. The three were similar, as shown by the proximate and ultimate analyses in Table 1 (moisture-free basis). Coals SA and RA generally contain about 5 per cent. moisture and coal P about 3.5 per cent. moisture on the as-received basis. The large difference in the ash contents of the coals, amounting to practically 10 per cent. between SA and RA, and P, makes difficult a direct comparison of their qualities. In the second section of Table 1 the figures have been put upon an ash-free basis., This table shows that these coals are closely alike. The ultimate analyses are almost identical except for the higher nitrogen content of

Jan 1, 1930

By Leslie F. Tedsen, John E. Dorn, Alan E. Flanigan

It is necessary occasionally to use aluminum-alloy sheet where moderately elevated temperatures are encountered. Considerable attention has been directed toward determining the influence of "artificial aging" on the room-temperature properties of the precipitation-hardenable alloys, as testified by numerous company reports and by references I to 4. Investigations on the properties at elevated temperatures are few, however, and have not always covered the range of times and temperatures of greatest interest. The present investigation was instituted to overcome this deficiency. The work was done for the Office of Production Research and Development of the War Production Board, under the supervision of the War Metallurgy Committee, as a part of the "restricted" Project NRC-548. It has been released for publication by the Office of Production Research and Development. AS is well known, the high-strength aluminum alloys achieve their remarkable properties as a result of precipitation-hardening. In production they are subjected to a solution heat-treatment followed by quenching, to retain the supersaturated solid solution. The solution treatment is followed by "aging" (precipitation-hard- ening) either at room temperature or at a suitable elevated temperature. A considerable increase in tensile and compressive yield stresses results from precipitation at room temperature ("natural aging"). Through the elevated-temperature process ("artificial aging") it is possible to obtain values of yield stress considerably higher than those attainable by natural aging. The increase in yield stress is accompanied by a smaller gain in ultimate tensile stress and by a decrease in elongation. During the first stages of artificial aging the yield stress increases steadily until it reaches a maximum value. In this condition the material is said to be "fully aged." Further exposure results in "averaging," attended by a steady decrease in yield stress. In the production of the artificially aged materials, temperatures and times are selected to achieve full aging. The following important characteristics are associated with the process: 1. The higher the temperature, the more rapidly is the fully aged condition attained. :7

Jan 1, 1946

By Leslie F. Tedsen, Alan E. Flanigan, John E. Dorn

It is necessary occasionally to use aluminum-alloy sheet where moderately elevated temperatures are encountered. Considerable attention has been directed toward determining the influence of "artificial aging" on the room-temperature properties of the precipitation-hardenable alloys, as testified by numerous company reports and by references I to 4. Investigations on the properties at elevated temperatures are few, however, and have not always covered the range of times and temperatures of greatest interest. The present investigation was instituted to overcome this deficiency. The work was done for the Office of Production Research and Development of the War Production Board, under the supervision of the War Metallurgy Committee, as a part of the "restricted" Project NRC-548. It has been released for publication by the Office of Production Research and Development. AS is well known, the high-strength aluminum alloys achieve their remarkable properties as a result of precipitation-hardening. In production they are subjected to a solution heat-treatment followed by quenching, to retain the supersaturated solid solution. The solution treatment is followed by "aging" (precipitation-hard- ening) either at room temperature or at a suitable elevated temperature. A considerable increase in tensile and compressive yield stresses results from precipitation at room temperature ("natural aging"). Through the elevated-temperature process ("artificial aging") it is possible to obtain values of yield stress considerably higher than those attainable by natural aging. The increase in yield stress is accompanied by a smaller gain in ultimate tensile stress and by a decrease in elongation. During the first stages of artificial aging the yield stress increases steadily until it reaches a maximum value. In this condition the material is said to be "fully aged." Further exposure results in "averaging," attended by a steady decrease in yield stress. In the production of the artificially aged materials, temperatures and times are selected to achieve full aging. The following important characteristics are associated with the process: 1. The higher the temperature, the more rapidly is the fully aged condition attained. :7

Jan 1, 1946

CONTENTS PAGE DANIELS, SAMUEL, LYON, A. J., and JOHNSON,. J. B.-Casting and Heat Treatment of Some Aluminum Copper-magnesium Alloys 1 ELLIS, O. W. and SCHEMNITZ, D. A.-Experiments on the Heat Treatment of Alpha-beta Brass : 4 ENOS, GEORGE M. and ANDERSON, ROBERT J.-Coatings. Formed on Corroded Metals and Alloys 5 COMSTOCK, GEORGE F.-Notes on the Hardness of Heat-treated Aluminum Bronze 6 Casting and Heat Treatment of Some Aluminum Copper-magnesium Alloys Discussion of the paper of SAMUEL DANIELS, A. J. LYON, and J. B. JOHNSON, presented at the Milwaukee Meeting, October, 1924, and issued, as Paper No. 1350-N, with MINING AND METALLURGY, July, 1924. D. HANSON and M. L. V. GAYLER, Teddington, England (written discussion).-At the National Physical Laboratory, the writers have made a number of researches on the relation between the constitution and mechanical properties of aluminum alloys of various types; the results obtained were in good general agreement with those of the authors. The writers, however, did not think that increasing the copper content of sand-cast low-copper duralumin to 4 per cent. necessarily caused a drop in the elongation to 1.5 per cent., as stated on page 9. In the case of sand-cast copper-aluminium alloys they had obtained much greater elongation, in some cases as great as 13 per cent. in heat-treated castings. For example, in a sand casting containing 3.5 per cent. of copper, a strength of 12 tons per square inch and an elongation of 13 per cent. were obtained; in a casting containing 4.5 per cent. copper, a tensile strength of 13 tons, and an elongation of 9 per cent. were obtained. These values were the maximum; the elongation varied considerably, being as low as 5 per cent. in some cases. In the writers' opinion, such variations are due more to unsoundness in the sand casting than to any other cause.

Jan 1, 1925

By C. S. Smith, L. W. Kempf, C. S. Taylor

The thermal conductivity of aluminum alloys is of considerable industrial importance. This is particularly true in such applications as internal-combustion engines where one of the principal reasons for the use of these alloys is their relatively higher thermal conductivity. In spite of this, relatively few data are available on this property of aluminum alloys. The reason is quite apparent to anyone concerned with the experimental determination of coefficients of thermal conductivity. This determination, in theory so simple, is extraordinarily difficult if any high degree of precision is desired. Fortunately, some .knowledge of the relationship between thermal and electrical conductivity has permitted the use of the latter physical property in deducing the relative approximate values of the thermal conductivities of metals. This fundamental relationship, first enunciated by Wiedemann and Franz' as applying to metallic elements and later shown by Lorenz2 to be applicable to alloys within a single metallic system, has been of service in the industrial application of metals. The electrical conductivity of metals is easily determined with a high degree of precision. It is, therefore, quite desirable that the relationship between electrical and thermal characteristics be determined with the greatest possible precision. This paper presents data on the electrical and thermal conductivities of a number of aluminum alloys of industrial importance. Literature on Thermal Conductivity of Aluminum Alloys Masumoto3 determined the electrical and thermal conductivities of 18 aluminum alloys. His results indicated a relatively constant relationship between thermal and electrical conductivity.

Jan 1, 1937

By E. C. Nelson

An equation is derived for calculating approximately the solubility of nitrogen in an alloy steel over a temperature range from 1200" to 1900°C using data on the effects of alloys on the activity coefficient of nitrogen in iron at 1600°C. Calculated values are compared with experimental data. STUDIES involving the solubility of nitrogen in complex iron alloys have been aided by a system devised by Lanenberg for calculating the solubility of nitrogen in ternary and higher alloys of iron at 1600C using available data on the activity coefficient of nitrogen in binary alloys. Calculated nitrogen solubilities agree well with experimental determinations on complex alloys,' and the calculation procedure is useful when experimental data on specific alloys are not required. A method for extending calculations of nitrogen solubilities in alloy steels to temperatures other than 1600°C would be useful because of the paucity of experimental data in this area. Assumptions which must be made to permit this calculation introduce an element of approximation; however, the calculation is useful in cases where a large number of alloys and temperatures are under consideration, and the precision of experimental measurements is not required. The activity coefficient can be freed from the isothermal restriction of Langenberg's calculation if it is assumed that the solution is "regular". This is a reasonably good assumption for solutions of nitrogen in iron alloys, because usually they are dilute and the heat of solution is relatively small. The presence of large amounts of certain alloying elements would make this assumption less tenable.3 One of the properties of a regular solution is: when "f" is the activity coefficient of a solute and "T" is the temperature in OK. If the activity coefficients at temperatures T and T2 are denoted by subscripts 1 and 2 respectively: The activity coefficient of nitrogen in a complex alloy then can be calculated at any temperature from the sum of the effects of the other solutes on the activity coefficient of nitrogen at 1600°C. It will be convenient to incorporate this expression into an equation which will give directly the logarithm of the solubility of nitrogen at any temperature in the presence of alloys. Two constants, the solubility of nitrogen in pure iron at 1600 "C and the partial molar heat of solution of nitrogen in iron are required. The heat of solution value of 1400 cal at 1600 °C quoted by Kubaschewski and vans will be used. The accuracy of the calculation will suffer if the heat of solution should change materially with temperature. In the absence of experimental data on the temperature dependence of this quantity, it will be expedient to restrict the application of the calcula-

Jan 1, 1963

By Raja V. Ramani, Ralph W. Barbaro

This paper presents an application of a Mixed Integer Programming (MIP) model to the problem of locating a centralized coal preparation plant and determining the production schedule for the mines. The system used for illustrating model application is hypothetical but realistic. It consists of three mines, two potential preparation plant sites, heavy media processing plant, and one market. The goal is to maximize the total profit of the system while satisfying the coal delivery schedule over a three year period meeting both quantity and quality requirements (ash, sulfur, and heat content). In addition to the base case, four different scenarios are analyzed. These four modifications are: (1) removing the flotation circuit from the preparation plant and sending all of the fines directly to the clean coal, (2) lowering the quality of coal from one of the mines, (3) applying discounts to the unselected site to improve its competitive position, and (4) adding a new mine. A detailed discussion of the base case and the effect of these four alternatives is presented.

Jan 1, 1983

By W. Hurst

What is entailed here is the extension of the sinzplified material balance formulas to encompass interference between oil fields. As previously reported, the ex-plicitness as so revealed for the cunzulative pressure drop as a function of all factors contributing to its change in the material balance equation, is now transcribed through the inter-conzmunicating aquifer to effect an increased pressure drop on an adjoining field by interference. Such is performed by mathematical analyses and the application of the Laplace transformations. What is accomplished is that the reiteration problems previously associated with interference studies are nullified, since volumetric changes for the fluids in situ are automatically adjusted by the explicitness so expressed, and what pertains to the superposition principle applies only to the impeded water drive upon a su.bject field, which is likewise incorporated in the over-all pressure drop that results. The mathematics treats with the rigorous solution of the problem, as well as with methods easily amenable to numerical interpretation by the practicing engineer. In all cases, however, what is deduced for areal extents, reveal interference between wells when time becomes large that further substantiate the analyses. Probably of equal significance, all variables and for/nation characteristics are accounted for. This applies to the differences in PVT analyses that occur from field to field and the physical parameters associated with the lithology of the reservoirs. The latter is deduced from a rigorous interpretation of the unsteady-state flow problem for sands of different permeabilities in series. Thus, what purports to be a trial-and-error calculation to include variations in sand conditions within the intercommunicating aquifer to define water drive has little importance compared to the designation of such paranzeters at the reservoir to constitute the essential criteria. INTRODUCTION In a recent publication, the reader has been introduced to the simplified material balance formulas,' It has been shown that the complexities formerly associated for identifying and determining reservoir pressure in the material balance relationship can be resolved by treating with the Laplace transformations, the inversion of which reveals pressure as an explicit function of all factors contributing to its change. For an under saturated oil reservoir, this constitutes an integrated effect from the inception of production; and for a saturated oil reservoir, such represents a survey traverse. However, what is most important, for the first time we are able to express the pressure change in a reservoir directly to the oil, gas and water produced, and to the physical parameters of the formation, in the same manner that reservoir pressure has served in the past to define well interference — which opens up this avenue of endeavor for investigating interference between oil fields. The occurrence of interference is by virtue of the juxtaposition of two or more oil reservoirs producing in the same aquifer. Thus, in any one field, the extended production so incurred creates a pressure lowering in the field, as well as in the aquifer, which can now be transcribed by these simplified material balance formulas to the adjoining reservoir to observe the increased pressure change so induced. These effects are retroactive from field to field, to reveal a pressure drop far in excess of normal depletion to evidence the interference pattern that can result. Such is the purpose for the present undertaking — to develop the mathematical physics treating with this phenomenon of interference between oil fields, employing the simplified material balance formulas. Since Ref. 1 often will be referred to in the text, it is identified as "The Simplification", in the same connotation that another paper has been referred to as the "Laplace Trans-formation. However, the amount of material to be covered in these passages is substantial; therefore, the total emphasis will be placed upon developing these fundamental ideas treating with interference rather than attempting to offer work curves, which always can be prepared. For the practical application of these simplified material balance formulas that form the framework of the present development, the reader will find a comprehensive treatment in the Appendix of Ref. 1, illustrating a factual field example. In essence, what is proposed by this presentation is to make available to the practicing engineer a simplified means to treat with interference between oil fields, independent of the complex machine computations that have attended such undertakings in the past. As the problem unfolds, a common pattern will be discernible, whereby the many reiteration processes that previously required computing devices are eliminated.

By J. A. Woolf, E. S. Leaver

The presence of soluble base metals in precious-metal ores usually precludes cyanidation as the best method of treatment. The laboratory experiments described in this paper show the possibility of cyanidation of gold-silver ores containing less than 0.5 per cent. of cyanide-soluble copper and the effect of zinc in the cyanide solution. Part I.—Copper in Cyanidation The proposed process of cyanidation of precious-metal ores containing copper is based on the regeneration of about 80 per cent. of the cyanide used in the dissolution of the copper. The method of regeneration involves a combination of the sulfide and the acid precipitation of the copper and silver. The resultant solution is made alkaline with lime, and the gold is precipitated with zinc dust. Solubility of Copper Minerals in Cyanide Solution In order to determine the solubility of copper minerals, including metallic copper, under the usual conditions for cyanidation, experiments were conducted with synthetic ores. Each ore sample was prepared by mixing the particular pure copper mineral with barren sea sand. Both the mineral and sand were ground to pass 100 mesh before they were thoroughly mixed. The percentage of copper in each head sample was determined by direct assay, excepting the metallic copper sample, which was computed on weights before mixing. Table 1 gives the results. Azurite, bornite, chalcocite, cuprite, malachite and finely divided metallic copper are readily and completely soluble under the usual conditions for cyanidation. Enargite and tetrahedrite are sufficiently soluble to cause an excessive loss of cyanide, and they also cause fouling of solutions with arsenic and antimony. Precious-metal ores containing small percentages of chalcopyrite or chrysocolla may give satisfactory returns with the usual cyanidation.

Jan 1, 1930

By E. C. Wright

The following article is based on observation of college graduates entering the steel industry in technical work made during the Past 25 Years, the first five of which were spent as a college instructor in two engineering schools, and the last 20 in the employ of a large steel company that has hired hundreds of engineering graduates for steel-mill operations. The college graduates encountered during this period have come from many colleges representing schools in Eastern States, Midwestern Universities, many Southern colleges, and many smaller colleges and normal training schools mostly in western Pennsylvania and Ohio. The college training of these students for engineering work naturally has varied widely and the educational qualifications of the entrants have been in many ways different. It was found at an early date that graduates of standard engineering colleges were much more adaptable than graduates in science from nontechnical schools. The engineering students seemed to be more suited to actual work in steel plants and in general were better able to grasp a knowledge of the operations they observed. However, although the graduates of engineering schools have had somewhat better training in physics, mathematics, and engineering, it has been a general and continual observation that most of the students employed have had inadequate training in the fundamental sciences. Since this discussion relates entirely to metallurgical engineers it should be emphasized that students taking metallurgical engineering courses in college seem to be poorly trained in organic chemistry-physics, physical chemistry, thermodynamics, and any higher form of mathematics than simple calculus. It has been noted frequently that young engineers faced with problems in a mill that involve some mathematics generally flounder badly, and that they have little conception of physical chemistry. Another common deficiency lies in the young graduate's lack of knowledge of where to look for the more detailed literature on any subject. He reverts instinctively to some college textbook whose coverage is usually very elementary. It is recommended that such textbooks contain a bibliography of the source literature. and that students be taught to use the original data. Many of the students had had previous courses in college dealing with metallurgical work such as steel melting, metallograhy, etc.r but it was found that their grasp of these subjects was extremely sketchy. It was soon realized that an ordinary engineering graduate could be taught more about steel melting and manufacturing processes in a few weeks in a plant than he could learn in a college course on such subjects. A similar statement may be made regarding the ability of students to conduct laboratory work. Their lack of technique and skill in handling equipment and setting up experiments was soon apparent. It became neces-

Jan 1, 1948

By E. C. Wright

The following article is based on observation of college graduates entering the steel industry in technical work made during the Past 25 Years, the first five of which were spent as a college instructor in two engineering schools, and the last 20 in the employ of a large steel company that has hired hundreds of engineering graduates for steel-mill operations. The college graduates encountered during this period have come from many colleges representing schools in Eastern States, Midwestern Universities, many Southern colleges, and many smaller colleges and normal training schools mostly in western Pennsylvania and Ohio. The college training of these students for engineering work naturally has varied widely and the educational qualifications of the entrants have been in many ways different. It was found at an early date that graduates of standard engineering colleges were much more adaptable than graduates in science from nontechnical schools. The engineering students seemed to be more suited to actual work in steel plants and in general were better able to grasp a knowledge of the operations they observed. However, although the graduates of engineering schools have had somewhat better training in physics, mathematics, and engineering, it has been a general and continual observation that most of the students employed have had inadequate training in the fundamental sciences. Since this discussion relates entirely to metallurgical engineers it should be emphasized that students taking metallurgical engineering courses in college seem to be poorly trained in organic chemistry-physics, physical chemistry, thermodynamics, and any higher form of mathematics than simple calculus. It has been noted frequently that young engineers faced with problems in a mill that involve some mathematics generally flounder badly, and that they have little conception of physical chemistry. Another common deficiency lies in the young graduate's lack of knowledge of where to look for the more detailed literature on any subject. He reverts instinctively to some college textbook whose coverage is usually very elementary. It is recommended that such textbooks contain a bibliography of the source literature. and that students be taught to use the original data. Many of the students had had previous courses in college dealing with metallurgical work such as steel melting, metallograhy, etc.r but it was found that their grasp of these subjects was extremely sketchy. It was soon realized that an ordinary engineering graduate could be taught more about steel melting and manufacturing processes in a few weeks in a plant than he could learn in a college course on such subjects. A similar statement may be made regarding the ability of students to conduct laboratory work. Their lack of technique and skill in handling equipment and setting up experiments was soon apparent. It became neces-

Jan 1, 1948

By Douglas M. Smith

Silver-gold ratios were studied at the Tayoltita epithermal vein deposit using channel sample, channel sample line, stope, ore body, and vein sample populations. The ratios are highly variable among individual channel samples (25:1 to greater than 500: 1) with both high and low values randomly distributed within ore bodies and veins. Whole vein ratios for the 14 most important ore producing structures range from 44: 1 to 105:1, and show zonal distribution relative to two small granitic stocks, low values closest to the intrusives. The zoned nature of the deposit suggests that the stocks, apophyses of an underlying batholith of late Eocene age, were the heat engines which powered the hydrothermal system responsible for ore deposition.

Jan 1, 1980

By W. O. Philbrook, R. H. Spitzer, F. S. Manning

A generalized mathematical model has been developed to describe the kinetics of the gaseous, topo-chemical reduction of porous hematite spheres. Gas-solid reduction is permitted at each of three advancing interfaces and is controlled by a complex series-parallel sequence of chemical and transport steps. Despite the fact that transport resistances are significant to the advance of each interface, little deviation from linear advance is predicted for the first 98 pct of reduction. Calculations to predict the movement of magnetite /wustite interface by a solid-state diffusion mechanism have been incorporated into the earlier dense-pellet model.' The porous-pellet model is found to give a better description than the dense-pellet one for McKewan's measurements2 of interface movements in dense polycrystalline hematite reduced in hydrogen-water vapor mixtures. THIS paper reports a continuation of work"3" directed toward the better understanding of gas-solid reactions and the development of mathematical models that may be helpful in the design or control of ore-reduction processes. Laboratory studies of the reduction of single oxide samples in tube furnaces normally employ an abundant excess of pure reducing gas. Reduction may appear to be adequately described by a model assuming gas-solid reaction solely at the iron/wustite interface.''' However, when iron ore is reduced in either a fixed bed or an efficiently operated counter-current column, there are portions of the bed where the partially spent gas is no longer capable of reducing wustite to iron. Nevertheless, the formation of the intermediate reaction products, wustite or magnetite, can and does continue. In order to account for this aspect of the reduction of beds of particles, three semiempirical mathematical models were devised.' One of these was for the limiting case of completely dense particles, and two alternatives were provided for porous particles. For purposes of the analysis, a dense pellet was defined as one in which the wustite and magnetite layers were impervious to the reducing gas when the atmosphere was capable of forming iron. In a porous pellet, the intermediate product layers were assumed to be sufficiently permeable to allow reducing gas to penetrate beyond the iron/wustite interface to form wustite and magnetite by removal of oxygen as a gaseous product rather than by a solid-state redfiction mechanism. Further progress required a better understanding of the reaction of the individual particles with the gas stream. A comprehensive mathematical treatment was developed' to describe the continually changing interplay of transport and reaction steps

Jan 1, 1967

By C. W. Clark, J. H. Schloen

Two papers have been written previously concerning operations at the Montreal East plant of Canadian Copper Refiners Limited. The first one,1 written in 1932, described silver-refinery operations at the time for producing silver and gold bullion from tankhouse anode slimes; the second,2 published in 1933, consisted of a description of the entire plant. Since publication of these papers the refinery has become the world's largest producer of refined selenium. The first selenium was produced in August 1934. Tellurium production on a commercial scale followed in October 1935. This paper will deal with selenium and tellurium production and also with present operations in the silver refinery. Blister cakes from Hudson Bay Mining and Smelting Co., Flin Flon, Manitoba, and commercial anodes from Noranda Mines Limited, Noranda, Quebec, are refined at Montreal East. Both these bullions have unusually high gold, selenium and tellurium content. The average assay of raw slimes produced from domestic and Noranda anodes is about 40 per cent Cu, 3600 oz. per ton Ag, 800 oz. per ton Au, 22 per cent Se and 3.7 per cent Te. EARLY SILVER-REFINERY OPERATIONS From the start of operations in 1931 until July 1934, the raw slimes were oxidize-roasted at 700° F. in a Nichols-Herreshoff furnace, acid¬leached with tankhouse discarded foul electrolyte (20 per cent H2SO4), filtered and charged directly to the doré furnace for refining to doré metal. This is the customary method for treating tankhouse anode slimes but was not suitable at the Montreal East plant because of the high selenium and tellurium content of our slimes. In the acid-leaching process about 50 per cent of the selenium and tellurium in the roasted slimes was dissolved in the electrolyte. These elements were recovered with the copper as a sludge in a small electrolytic

Jan 1, 1938

By Dwight E. Woodbridge

DuriNg April, Max, and June, 1910, I was in charge of an examination of the greater part of the Moa iron-ore area in Oriente Province, Cuba, on the north coast, near the east end of the island. My instructions, on arrival at the properties, were to check former estimates of tonnages and grades, and to re-examine the ore comprised in claims covering 44,727 acres. This work included the running of lines dividing the properties into co-ordinate planes, the boring of many thousand feet of holes spaced at the intersections of these co-ordinates, the taking of samples of the ore penetrated, the analysis of these samples for their various constituent minerals, and the determination of the results as to tonnages, depths, and grades, both for individual properties and for the entire group. Each section of every one of the thousand holes drilled was to be compensated for depth and grade with every other, a series of simple arithmetical calculations of no slight magnitude, the mere mechanical labor of which consumed much time, but finally resulted in giving a complete average of all the essential facts for the entire area of 18,000 hectares, Had it not been for the more than willing, active, and able co-operation of the officers of the Spanish-American Iron Co., from Charles F. Rand, President, and Jennings S. Cox, General .Manager, down to the most humble water-carrier, the work would have consumed far more time than it did. The lands thus systematically explored by me were comprised in the following denouncements: Punta Gorda, Yaminiguey, Baracoa secunda, Sagua, Moa, Yajrumaje, Lirio, and Cabanas, all of which were massed as the Moa group, so called, and cover an area of 13,832 hectares, or 34,179 acres. Some 10,000 acres additional to this was included in neighboring properties, lying between Moa and the east end of the island, the Buena Vista,

Jan 1, 1912