Search Documents

By Pedro G. Salom

I HAVE had an opportonity, within the last few months, of making a large number of physical and chemical tests of steel for boiler and ship-plate, which has been, and is now being, used principally for the United States Government cruisers, now building in Mr. John Roach's yard, at Chester, Pa. Through the courtesy of the Messrs. Houston, of the Chester Rolling Mills, I have the honor to lay before the members of the Institate the results of these tests. These results have developed some points in regard to the nature of steel, which are more or less new, and which, I hope, will prove interesting. The original specifications, as regards the manner of testing, were so inipracticable (when their severity mas taken into consideration), that the keel of the first vessel, which will be launched next month, would, had they been carried out, probably not have been laid until next year. At my suggestion, in order to simplify and expedite the immense amount of testing that had to be done, the Naval Advisory Board was induced, after considerable discussion, to alter the specifications, so as to test each heat, instead of each lot of twenty plates, but reserved the right of making the quenching-test on a piece from each ingot, after it had been rolled. This relieved us from the anxiety of having a lot of plates rejected, after they had beell rolled and sheared, by reason of the presence of one or two plates which might have been injured in heating or rolling, or which might not have been able to stand the tests; while it insured the Government in obtaining a uniform quality of steel, and prevented the temptation to introduce a half-dozen or more had plates in a lot, and run the risk of their being selected as the testplates. I give below a portion of the original specifications, as prescribed

Jan 1, 1884

By B. C. Raynes

IN the early part of 1952, under the auspices of the U. S. Atomic Energy Commission, Horizons Inc. undertook an investigation dealing with the preparation of high purity thorium metal in order to develop an economically competitive production process for this metal based on a recovery of the metal by a fused salt electrolysis, since a survey of the literature of thorium chemistry indicated that electrolytic methods had not received much attention, despite the consideration that electrochemical production methods often offer attractive commercial potentialities. Thorium metal has been prepared by methods which fall into four general categories: 1) reduction of halides or double halides; 2) reduction of the oxide; 3) thermal decomposition of halides; and 4) electrolytic methods. Some of the important results obtained by various investigators since about 1900 in recorded attempts to prepare pure thorium metal are summarized in Table I. A bibliography of pertinent literature is included in this paper. Thorium is strongly electropositive and possesses a great affinity for oxygen and nitrogen. As a result the prospects for the production of high purity thorium from aqueous media or oxygen bearing compounds are remote. The most promising and profitable area of investigation for production of thorium metal lies in fused salt electrolysis. Thorium has been produced previously by this technique from halide salts in fused alkali chloride eutectic mixtures. Until recently, however, the lack of known large uses for thorium has inhibited the investigation of these methods. The basic problem in an investigation into fused salt production methods for thorium is to develop a suitable fused salt system for the economic preparation of thorium. The first portion of the work in these laboratories was a small scale investigation of the electrolysis of potassium thorium fluoride, KThF5, under a variety of conditions. High purity thorium was prepared in this manner, but the process did not appear to offer the simplest and most attractive continuous commercial operation. The work reported here relates to an all-chloride system employing thorium chloride as the cell feed. ThCL4 was produced as an anhydrous material stabilized in molten sodium chloride. This product, further diluted in NaCl, was subjected to electrolysis. The electrolytic process has been studied in cells capable of holding up to 50 lb total salt charge. Ductile, pure thorium metal has been reproducibly obtained in this operation. Considerable experimentation was carried out in the preparation of ThCL as a cell feed free from moisture, oxides, and other impurities. Thorium was cathodically deposited as a coarsely crystalline powder interspersed with residual bath salts. Aqueous procedures for separating and recovering the metal were developed. The thorium metal powder obtained has been evaluated with respect to its hardness, chemical purity, and certain other physical properties. Preparation of ThC1,—Thorium chloride, and the chlorides of some other metals (aluminum, beryllium, tantalum, zirconium, etc.) cannot be obtained from aqueous solution by direct heating and evaporation. Evaporation and heating of a solution of thorium chloride yields a hydrated salt or partially hydrated salt, and finally Tho,. Anhydrous thorium chloride is obtained by forming a hydrated ammonium chloride complex salt in acidified water solution, dehydrating this compound, and finally decomposing the double salt and subliming the ammonium chloride component. Various methods for the preparation of anhydrous thorium chloride, in accordance with this concept, were investigated as indicated in Table I1 from hydrated thorium chloride (ThCl, . 3H2O), and from thorium oxycarbonate (ThOCO,). In the method found most satisfactory for this work, thorium oxycarbonate was dissolved in an excess of concentrated HC1 to give a clear yellow solution. At least 2 mol NH,Cl were added to the solution per mol of contained thorium. Ammonium thorium chloride hydrate was crystallized from solution by cooling and saturation with HC1. The resultant complex, (NH,Cl),ThCl;xH,O, was dehydrated by evaporation at 130° to 150°C and thoroughly dried at about 250°C. The dried ammanium thorium chloride was then mixed with sodium chloride in proportions to form NaThCL or to produce a ThCL4-NaCl mixture with a given thorium content. The ammonium chloride was sublimed off at temperatures above 500°C in an inert atmosphere furnace to give an anhydrous chloride source electrolyte, essentially free of Tho, and of NKC1.

Jan 1, 1958

By W. C. Winegard, C. J. Beinjessner

PREVIOUS investigations 1,2 of Fe3P described by pearson3 and schubert4 show that Fe3P has a bct unit cell having four Fe3P tetrahedra centered around each lattice point. The space group is 14, No. 82, and all atoms occupy general positions 8(g). The cell dimensions3 are: a = 9.090, c = 4.446 kX, with an axial ratio of c/o = 0.4891. We have measured the lattice parameters of Fe3P, using a Fe as an internal temperature standard, at 23°, 414°, and 678°C and computed the thermal expansion over this temperature range. The Fe,P was prepared by melting under vacuum (after flushing with argon) a commercially pure iron and "ferrophosphor" in a high-frequency induction furnace. Part of the ingot was crushed for X-ray examination and for chemical analysis. X-ray diffraction and light microscopy indicated iron phosphide (Fe3P) present as the major constituent and a small amount (about 5 pct) of a Fe. Chemical analysis showed 0.05 wt pct Si, 0.008 wt pct N, 0.018 wt pet C, and less than 0.02 wt pct each of other metallic elements. X-ray diffraction powder patterns were obtained from a mixture of iron and Fe3P sealed in an evacuated quartz capsule using a Unicam high-temperature

Jan 1, 1968

By E. J. Fasiska, L. Zwell

PREVIOUS investigations 1,2 of Fe3P described by pearson3 and schubert4 show that Fe3P has a bct unit cell having four Fe3P tetrahedra centered around each lattice point. The space group is 14, No. 82, and all atoms occupy general positions 8(g). The cell dimensions3 are: a = 9.090, c = 4.446 kX, with an axial ratio of c/o = 0.4891. We have measured the lattice parameters of Fe3P, using a Fe as an internal temperature standard, at 23°, 414°, and 678°C and computed the thermal expansion over this temperature range. The Fe,P was prepared by melting under vacuum (after flushing with argon) a commercially pure iron and "ferrophosphor" in a high-frequency induction furnace. Part of the ingot was crushed for X-ray examination and for chemical analysis. X-ray diffraction and light microscopy indicated iron phosphide (Fe3P) present as the major constituent and a small amount (about 5 pct) of a Fe. Chemical analysis showed 0.05 wt pct Si, 0.008 wt pct N, 0.018 wt pet C, and less than 0.02 wt pct each of other metallic elements. X-ray diffraction powder patterns were obtained from a mixture of iron and Fe3P sealed in an evacuated quartz capsule using a Unicam high-temperature

Jan 1, 1968

By Nathan C. Rockwood

THE title of this paper, I understand, was suggested by professional mining engineers as an opportunity for someone to pose problems rather than to offer solutions for them, but the paper will merely attempt to pose some of the production problems of the mineral aggregates industry in such manner as to create professional interest in their solution by the mining engineer, geologist, geochemist and the metallurgical engineer versed in mineral-dressing technique. DEFINITION OF MINERAL AGGREGATES "Mineral aggregates" may be defined as fragments of any rock or mineral used to supply bulk or volume or substance for a given purpose. For example, mineral aggregates are used in portland-cement concrete to provide bulk with the expenditure of the least feasible amount of cement binder. Mineral aggregates are used without portland cement or bituminous binder in highway and railway roadbeds to provide substance, to carry loads. Mineral aggregates are used in filters for water and sewage, to provide substance for the liquid to trickle through. These are only a few typical uses of mineral aggregates. For all these uses, strength, toughness, resistance to abrasion, and durability are usually prime requisites; so, while theoretically mineral aggregates may be of any mineral composition, what really is desired is a mineral composition as nearly inert under the conditions of use as anything of earthly origin can be. EXPLORATION AND POSSIBILITIES OF DEVELOPMENT The distribution of deposits of mineral aggregate is universal, since almost any part of the earth's crust can be used; even the top soil is sometimes used in stabilized surfacing for highways or airport runways. Nevertheless there is ample opportunity for exercise of the talents of the mining engineer and the geologist in finding the particular deposit that will be most economical to develop, keeping in mind such considerations as: (1) quality and mineralogical characteristics of the material; (2) size and permanency of the market; (3) final cost of opening and development of the deposit; (4) selection of location of plant; (5) methods and costs of distribution of the product in comparison with both present and possible future competition; (6) selection of the proper type of operating equipment; (7) estimation of probable waste products and their disposal. These are typical but there are other considerations also. Because profit margins are far smaller than in any comparable mining operation, it is all the more logical to assume that a higher degree of expert knowledge is desirable to make a success of a mineral-aggregates business. The industry has much engineering talent in its operating branch, but it lacks, to a considerable

Jan 1, 1943

By H. Foster Bain

THE "miracle of production." which was such an essential element in winning the European war, was nowhere more in evidence than in our Western States. In shipbuilding alone the Pacific Coast States -et a mark never before equaled, and in production of war goods of many kinds, both Rocky Mountain and Coast States accomplished more than their proportionate share if measured by population standards. This was only possible because of the building of immense new plants of many types, largely financed with Government money. Their operation has built up payrolls in the West and brought a measure of prosperity which Westerners are naturally anxious to have made permanent. A widespread doubt obtains, however, throughout the nation and even in the Western States themselves, as to whether, and if so to what extent, this may prove possible. The question has been raised as to whether the national treasury has not been raided to stock the Western ranges with a voracious breed of white elephant .

Jan 1, 1945

By L. D. HUNTOON

MY first article on Canadian Gold, published in the Canadian Mining Magazine in 1911 expressed the view that the Hollinger mine would repay all the money invested and that other mines would be developed in this area. Many published forecasts have since been made. Quoting from the Northern Miner of Oct. 29, 1931: "It will be noted in studying the chart prepared by this engineer that his forecast for 1931 at $50,000,000 was too modest, as the output for this country this year will be closer to $54,000,000."

Jan 1, 1932

By Frederic P. Dewey

THE Bureau of the Mint of the United States Treasury maintains 13 offices for the purchase of gold-bullion, and this paper describes an investigation to establish the reasonable differences in the assay-results at the various institutions which may be commercially allowable in the settlements between them. Beginning with the comparative assay of proof-gold at the Philadelphia mint and the Utrecht mint, which shows 0.00002 as the closest agreement now possible, eight tables of comparative results, taken from the regular work of the service, are given. These tables begin with very fine gold, produced in an electrolytic refinery, showing close agreement. in the assay-results, and follow through decreasing gold fineness and . increasing amounts and complexity of base metals to very impure and complex bars produced at cyanide-mills, some of which give widely-varying results. Next is given a series of results on samples, prepared and sent out to various laboratories in the service, to test the influence of different metals and various combinations upon the' agreement of the assay-results; 11 samples were sent out and each one was assayed from 44 to 71 times, making a total of 623 assays. To these are added 107 assays of identical samples of coin-gold. On a previous occasion,' I have endeavored to show the degree of accuracy that may be expected in the ordinary everyday analysis of various materials, and on another occasion2 I

Aug 1, 1909

By Glenn S. Wyman

CHUQUICAMATA, located in northern Chile in the Province of Antofagasta, is on the western slope of the Andes at an elevation of 9500 ft. Because of its position on the eastern edge of the Atacama Desert, the climate is extremely arid with practically no precipitation, either rain or snow. All primary blasting in the open-pit mine at Chuquicamata is done by the churn drill, blasthole method. Since 1915, when the first tonnages of importance were removed from the open pit, there have been many changes in the blasting practice, but no clear-cut rules of method and procedure have been devised for application to the mine as a whole. One general fact stands out: both the ore and waste rock at Chuquicamata are difficult to break satisfactorily for the most efficient operation of power shovels. Numerous experiments have been made in an effort to improve the breakage and thereby increase the shovel efficiency. Holes of different diameter have been drilled, the length of toe and spacing of holes have been varied, and several types of explosives have been used. Early blasting was done by the tunnel method. The banks were high, generally 30 m, requiring the use of large charges of black powder, detonated by electric blasting caps. Large tonnages were broken at comparatively low cost, but the method left such a large proportion of oversize material for secondary blasting that satisfactory shovel operation was practically impossible. Railroad-type steam and electric shovels then in service proved unequal to the task of efficiently handling the large proportion of oversize material produced. The clean-up of high banks proved to be dangerous and expensive as large quantities of explosive were consumed in dressing these banks, and from time to time the shovels were damaged by rock slides. As early as 1923 the high benches were divided, and a standard height of 12 m was selected for the development of new benches. The recently acquired Bucyrus-Erie 550-B shovel, with its greater radius of operation compared to the Bucyrus-Erie 320-B formerly used for bench development, allowed the bench height to be increased to 16 m. Churn drill, blasthole shooting proved to be successful, and tunnel blasts were limited to certain locations where development existed or natural ground conditions made the method more attractive than the use of churn drill holes. Liquid oxygen explosive and black powder were used along with dynamite of various grades in blast-hole loading up to early 1937. Liquid oxygen and black powder were discontinued because they were more difficult to handle due to their sensitivity to fire or sparks in the extremely dry climate. At present ammonium nitrate dynamite is favored because of its superior handling qualities and its adaptability to the dry condition found in 90 pct of the mine. In wet holes, which are found only in the lowest bench of the pit and account for the remaining 10 pct of the ground to be broken, Nitramon in 8x24-in. cans, or ammonium nitrate dynamite packed in 8x24-in. paper cartridges, is being used. This latter explosive, which is protected by a special antiwetting agent that makes the cartridges resistant to water for about 24 hr, currently is considered the best available for the work and is preferred over Nitramon. Early churn drill hole shots detonated by electric blasting caps, one in each hole, gave trouble because of misfires caused by the improper balance of resistance in the electrical circuits. Primarily, it was of vital importance to effect an absolute balance of resistance in these circuits, the undertaking and completion of which invariably caused delays in the shooting schedule. Misfires resulting from the improper balance of electrical circuits, or from any other cause, were extremely hazardous, since holes had to be unloaded or fired by the insertion of another detonator. The advent of cordeau, later followed by primacord, corrected this particular difficulty and therefore reduced the possibility of missed holes. After much experimentation, the blasting practice evolved into single row, multihole shots, with the holes spaced 4.5 to 5 m center to center in a row 7.5 to 8 m back from the toe. Sucti shots were fired from either end by electric blasting caps attached to the main trunk lines of cordeau or primacord. The detonating speed of cordeau or primacord gave the practical effect of firing all holes instantaneously. Double row and multirow blasts, fired instantaneously with cordeau or primacord, proved to be unsatisfactory in the type of rock found at Chuquica-

Jan 1, 1953

By Glenn S. Wyman

CHUQUICAMATA, located in northern Chile in the Province of Antofagasta, is on the western slope of the Andes at an elevation of 9500 ft. Because of its position on the eastern edge of the Atacama Desert, the climate is extremely arid with practically no precipitation, either rain or snow. All primary blasting in the open-pit mine at Chuquicamata is done by the churn drill, blasthole method. Since 1915, when the first tonnages of importance were removed from the open pit, there have been many changes in the blasting practice, but no clear-cut rules of method and procedure have been devised for application to the mine as a whole. One general fact stands out: both the ore and waste rock at Chuquicamata are difficult to break satisfactorily for the most efficient operation of power shovels. Numerous experiments have been made in an effort to improve the breakage and thereby increase the shovel efficiency. Holes of different diameter have been drilled, the length of toe and spacing of holes have been varied, and several types of explosives have been used. Early blasting was done by the tunnel method. The banks were high, generally 30 m, requiring the use of large charges of black powder, detonated by electric blasting caps. Large tonnages were broken at comparatively low cost, but the method left such a large proportion of oversize material for secondary blasting that satisfactory shovel operation was practically impossible. Railroad-type steam and electric shovels then in service proved unequal to the task of efficiently handling the large proportion of oversize material produced. The clean-up of high banks proved to be dangerous and expensive as large quantities of explosive were consumed in dressing these banks, and from time to time the shovels were damaged by rock slides. As early as 1923 the high benches were divided, and a standard height of 12 m was selected for the development of new benches. The recently acquired Bucyrus-Erie 550-B shovel, with its greater radius of operation compared to the Bucyrus-Erie 320-B formerly used for bench development, allowed the bench height to be increased to 16 m. Churn drill, blasthole shooting proved to be successful, and tunnel blasts were limited to certain locations where development existed or natural ground conditions made the method more attractive than the use of churn drill holes. Liquid oxygen explosive and black powder were used along with dynamite of various grades in blast-hole loading up to early 1937. Liquid oxygen and black powder were discontinued because they were more difficult to handle due to their sensitivity to fire or sparks in the extremely dry climate. At present ammonium nitrate dynamite is favored because of its superior handling qualities and its adaptability to the dry condition found in 90 pct of the mine. In wet holes, which are found only in the lowest bench of the pit and account for the remaining 10 pct of the ground to be broken, Nitramon in 8x24-in. cans, or ammonium nitrate dynamite packed in 8x24-in. paper cartridges, is being used. This latter explosive, which is protected by a special antiwetting agent that makes the cartridges resistant to water for about 24 hr, currently is considered the best available for the work and is preferred over Nitramon. Early churn drill hole shots detonated by electric blasting caps, one in each hole, gave trouble because of misfires caused by the improper balance of resistance in the electrical circuits. Primarily, it was of vital importance to effect an absolute balance of resistance in these circuits, the undertaking and completion of which invariably caused delays in the shooting schedule. Misfires resulting from the improper balance of electrical circuits, or from any other cause, were extremely hazardous, since holes had to be unloaded or fired by the insertion of another detonator. The advent of cordeau, later followed by primacord, corrected this particular difficulty and therefore reduced the possibility of missed holes. After much experimentation, the blasting practice evolved into single row, multihole shots, with the holes spaced 4.5 to 5 m center to center in a row 7.5 to 8 m back from the toe. Sucti shots were fired from either end by electric blasting caps attached to the main trunk lines of cordeau or primacord. The detonating speed of cordeau or primacord gave the practical effect of firing all holes instantaneously. Double row and multirow blasts, fired instantaneously with cordeau or primacord, proved to be unsatisfactory in the type of rock found at Chuquica-

Jan 1, 1953

By Glenn S. Wyman

CHUQUICAMATA, located in northern Chile in the Province of Antofagasta, is on the western slope of the Andes at an elevation of 9500 ft. Because of its position on the eastern edge of the Atacama Desert, the climate is extremely arid with practically no precipitation, either rain or snow. All primary blasting in the open-pit mine at Chuquicamata is done by the churn drill, blasthole method. Since 1915; when the first tonnages of importance were removed from the open pit, there have been many changes in the blasting practice, but no clear-cut rules of method and procedure have been devised for application to the mine as a whole. One general fact stands out: both the ore and waste rock at Chuquicamata are difficult to break satisfactorily for the most efficient operation of power shovels. Numerous experiments have been made in an effort to improve the breakage and thereby increase the shovel efficiency. Holes of different diameter have been drilled, the length of toe and spacing of holes have been varied, and several types of explosives have been used. Early blasting was done by the tunnel method. The banks were high, generally 30 m, requiring the use of large charges of black powder, detonated by electric blasting caps: Large tonnages were broken at comparatively low cost, but the method left such a large proportion of oversize material for secondary blasting that satisfactory shovel operation was practically impossible: Railroad-type steam and electric shovels then in service proved unequal to the task of efficiently handling the large proportion of oversize material produced. The clean-up of high banks proved to be dangerous and expensive as large quantities of explosive were consumed in dressing these banks, and from time to time the shovels were damaged by rock slides. As early as 1923 the high benches were divided, and a standard height of 12 m was selected for the development of new benches. The recently acquired Bucyrus-Erie 550-B shovel, with its greater radius of operation compared to the Bucyrus-Erie 320-B formerly used for bench development, allowed the bench height to be increased to 16 m. Churn drill, blasthole shooting proved to be successful, and tunnel blasts were limited to certain locations where development existed or natural ground conditions made the method more attractive than the use of churn-drill holes. Liquid oxygen explosive and black powder were used along with dynamite of various grades in blasthole loading up to early 1937. Liquid oxygen and black powder were discontinued because they were more difficult to handle due to their sensitivity to fire or sparks in the extremely dry climate. At present ammonium nitrate dynamite is favored because of its superior handling qualities and its adaptability to the dry condition found in 90 pct of the mine. In wet holes, which are found only in the lowest bench of the pit and account for the remaining 10 pct of the ground to be broken, Nitramon in 8x24-in. cans, or ammonium nitrate dynamite packed in 8x24-in. paper cartridges, is being used. This latter explosive, which is protected by a special antiwetting agent that makes the cartridges resistant to water for about 24 hr, currently is considered the best available for the work and is preferred over Nitramon. Early churn drill hole shots detonated' by electric blasting caps, one in each hole, gave trouble because of misfires caused by the improper balance of resistance in the electrical circuits. Primarily, it was of vital importance to effect an absolute balance of resistance in these circuits, the undertaking and completion of which invariably caused delays in the shooting schedule. Misfires resulting from the improper balance of electrical circuits, or from any other cause, were extremely hazardous, since holes had to be unloaded or fired by the insertion of another detonator. The advent of cordeau, later followed by primacord, corrected this particular difficulty and therefore reduced the possibility of missed holes. After much experimentation, the blasting practice evolved into single row, multihole shots, with the holes spaced 4.5 to 5 m center to center in a row 7.5 to 8 m back from the toe. Such shots were fired from either end .by electric blasting caps attached to the main trunk lines of cordeau or primacord. The detonating speed of cordeau or primacord gave the practical effect of firing all holes instantaneously. Double row and multirow blasts, fired instantaneously with cordeau or primacord, proved to be unsatisfactory in the type of rock found at Chuquica-

Jan 1, 1952

By ERNEST W. ELLIS

MORE or less contradictory findings as to the most satisfactory feed for concentration tables of the Wilfley type is shown by the diversity of opinion among experimenters. Prof. R. H. Richards,l as a result of his work, favors classification. On the other hand the work of Messrs. Cox, Gibbins, and Porter,' of McGill University, points in general to the desirability of screen-sized feed The ore used was obtained from the West mill of the Bunker Hill and Sullivan Mining and Concentrating Co., Kellogg, Idaho, and consisted of argentiferous galena in a gangue of quartzite and siderite. The natural feed was taken from the launder supplying the Fahrenwald classifier. Classified feed was collected from each of the ten spigots of this same classifier. From the natural feed the screen-sized feed was pre- pared in the laboratory. All three types of table feed were therefore derived from the actual mill circuit of a large plant.

Jan 1, 1926

By R. W. Raymond

The " law of the apex," with its vague and impracticable " extra-lateral rights," is defended—if it is defended at all— on the ground that it is required by the peculiar conditions of the mineral deposits or of the mining industry in those States and Territories in which it is operative. As I have repeatedly attempted to show, in papers read before the Institute, and most recently in an article on " The Relation of the Mining Law of the United States to the Davelopment of its Mineral Resources," published in Mr. Rothwell's Mineral Industry for 1894, there is now (whatever may have been the case formerly) no peculiarity of conditions in the regions referred to which warrants the subjection of their mining industry to a burden so vexatious and injurious as this law imposes. I have called attention to the absolute freedom from expensive litigations over mining titles enjoyed by all other States in the Union and all other regions in the world where the absurd extra-lateral right does not exist.

Jan 1, 1896

By F. B. Harris

MINE surveying and engineering at the various properties of the United States Smelting Refining and Mining Company has developed and increased in importance steadily as mining methods have changed and expanded, both in the development of ore bodies and in the methods and styles of stoping. Most important to satisfactory engineering practice, and secondary -only to accuracy and precision, is the preservation of all data relative to surveys and calculations so that it is readily available for use at all times and in -such form that it is permanent, easily found, and usable. The first consideration for a proper, accurate, and practical start for surveys and efficient engineering at any property is an accurate triangulation net and system of co-ordinates. This has been our practice and the first step seas to select a base line, readily accessible and easily measured, situated preferably on an even grade where the difference of elevation between the two -end monuments was not too great and -the distance was long enough for practical use. Permanent concrete monuments were built for these base-line points so constructed that they could be easily recognized and were visible. Precise levels were run on this base 'line and the elevation (sea level datum) if possible was established at each end monument. The distance was carefully measured many times, back and forward, by using a tape that had been standardized by the National Bureau of Standards. The tape was supported at ,each 25-ft interval on stakes which had been brought to grade between each measuring point. All conditions were

Jan 1, 1948

By Robert W. Coughlin

Pulverized coal has been introduced at the anode where it is oxidized during the electrowinning of metals from their aqueous solutions This substitutes an electrochemical reaction between coal and water for the usual oxygen-evolving half-cell reaction at the anode, with the result that overall cell potential is significantly lowered and the consumption of electrical energy is correspondingly reduced. Experimental results are reported for electrowinning copper as an example of this novel modification of the electrowinning process in this example, the use of coal lowered the consumption of electricity by two-thirds of the requirement of the conventional process When the potential electrical energy of the coal consumed is considered the new, coal-assisted process consumes about 45% less energy, and the energy costs (combined costs of coal and electricity) are reduced by about 50%.

Jan 1, 1981

By P. S. Miller, S. H. Ash

EXTENSIVE and diversified resources justify large populations and great industries. To carry on the business of commerce and meet the demands of large populations, the utilization of tunnels in some form for transportation purposes constitutes an important link in modern civilization. The driving of tunnels has been appropriated by the tunneling branch of the heavy-construction industry, and the progressive steps taken by modern tunnel builders were not even dreamed of 50 years ago. Great strides have been made toward more rapid progress in tunneling in the United States during the past 10 years. Tunneling consists of a definite cycle of operations developed from ideas that are crystallized and translated into action programs through various engineering phases that begin with the first preliminary survey and do not end until the job is completed. Once the line of the bore is established and a time set for the completion of the work, the face must advance according to estimates prepared before the work commences. This schedule must be followed in regular sequence from the moment the drills start against a new face of rock until they are ready again to drill the succeeding face, constituting a round.1 Mining is largely tunneling carried on under conditions often more inherently hazardous than actual tunnel construction, but for various reasons1 tunneling is more hazardous than mining in any branch of the mineral industry, On the other hand, obstacles are sometimes encountered in heavy-construction tunneling projects that when met in mining enterprises do not offer comparable tasks to avoid or overcome them. One of these is the existence of water under high pressures. In mining enterprises, various alternatives offer a solution in driving a tunnel, even to the extent of its discontinuance or the abandonment of the mine, but a "construction" tunnel usually must go forward because some important project depends largely if not entirely upon it. This paper describes an unusual method of driving a water-supply tunnel through rock carrying water under pressures and conditions that did not permit the use of ordinary tunneling methods. THE DELAWARE AQUEDUCT The new Delaware aqueduct is a Manhattan project of some magnitude; when completed, it will contain what probably will be, for some time to come, the longest tunnel in the world. Various features in its construction are currently described in the trade journals of the construction industry, and informative engineering details are given in the Delaware Water Supply News, published twice a month by the Board of Water Supply of the City of New York. Work was begun on this project on March 24, 1937. The tunnel will convey water from reservoirs at the headwaters of the Delaware River to the City of New York.

Jan 1, 1942

By W. B. Plank

I HAVE been asked by the Chairman of the Engineering Education Committee to outline what the engineering colleges would like the mining companies to do with the young engineer just, out of college. It has been suggested that, because my own personal experience has been almost entirely within the coal industry, I handle this subject from that view- point. Many thoughtful engineering educators are today wondering what effect the present employment policies of many industrial companies are going to have on the young man just starting out in his profession. Since before the World War large industrial concerns, such as those in the electrical and mechanical industries, have gone to the colleges to interview 'likely graduates until today there has developed in most of our engineering colleges, especially in the eastern part of the country, what appears to be a lively competition on the part of these companies in bidding for the young graduate engineer. The employers of mining engineers, with one or two exceptions, have not yet begun to enter this competition. It remains to be seen how serious this situation will become, how it will affect the training of other engineers, and what effect, if any, it will have on the mind of the young man about to enter college who may be inclined to take up mining engineering, but who gains the impression from this well advertised employment service just mentioned that there is no opportunity for him in the mineral industry as com- pared with the opportunities offered in say civil, mechanical, and electrical engineering.

Jan 1, 1929

By G. Sachs, C. C. Chow, L. J. Klingler

Most structural parts which are heat treated are designed using strength properties which have been determined in the principal direction of the wrought material. For example, for rolled or drawn materials, properties are given for the rolling or drawing direction. The structures, however, may be loaded so that the critical stress is in some direction other than that for which the properties of the material are known. Investigations of forged products,123 have shown that while the yield strength and tensile strength of carbon steel billets and bars vary little with the direction of the test specimen in relation to the fiber, the contraction in area in tension tests and the impact strength in notched bar impact tests decrease in the transverse direction. The contraction in area and, consequently, the fracture stress of hard aluminum and magnesium alloy forg-ings have also been found to be lower in the transverse direction. An investigation on aluminum alloy plate4 likewise has shown the dependence of the fracturing characteristics upon the direction* of the test specimens, the longitudinal direction being considerably stronger than the transverse direction and the normal direction, with the normal direction being the least strong. The variation of properties with direction has been explained by a type of anisotropy called mechanical anisot-ropy. This anisotropy results from the elongation, in the direction of the principal strain, of certain phases, inclusions, and/or cavities in the metal during working. A mechanical fibering is thus produced which seems to persist through annealing and heat treatment. This investigation was initiated to determine the flow stress and fracture stress, at high hardness levels, at 90° to the rolling direction in a round steel bar. It is this direction which receives the critical stress in drawing dies machined from round bars. Preliminary tests showed a large difference in properties between the 0° and 90° directions. Consequently, it was felt that a more complete investigation, utilizing several types of tests, was warranted to determine the flow and fracture characteristics of a steel at various orientations, for a number of hardness levels. This investigation was conducted on an air hardening nondeform-ing die steel. Material and Procedure The distribution of properties was made on a 3-in. round bar of annealed high-carbon, high chromium steel of the following analysis: Pct Carbon................... 1.53 Manganese................ 0.39 Silicon.................... 0.27 Chromium................ 11.76 Vanadium................. 0.25 Molybdenum.............. 0.81 The 3-in. bar was produced from an 8-in. ingot, which was annealed and forged to a 4-in. square billet. The billet was annealed and rolled to a 3-in. round which was then annealed and straightened. This steel is an air hardening die steel which has very good dimensional stability on hardening; therefore, the residual stresses resulting from hardening would be expected to be low. A hardness survey across the diameter of the annealed bar showed no difference in hardness from the center to the outside. However, the test sections of all the specimens were taken approximately half way between the center of the bar and the surface to avoid any surface effect or possible porosity at the center. Tension, compression and bend tests were made on specimens hardened and tempered at six different temperatures. The tension test specimens, Fig 1, were machined from the bar at orientations of 0, 22.5, 45, 67.5 and 90° from the axis of the steel bar. The specimens were rough machined, heat treated and then ground to size. The test section on each specimen was lapped in a direction parallel to the axis of the specimen to remove any transverse scratches which might act as stress raisers. The specimens were tested in fixtures which insured concentricity of loading of less than 0.001 in.5 The transverse strains were measured with a radial strain gauge,5 the least count of which was 0.0001 in. change in diam. The compression specimens, Fig 1, were machined from the bar at ori-

Jan 1, 1950

By W. H. C. SIMMONDS

The mining, metallurgical, and petroleum industries can be viewed as financial or as social institutions or both. The differences between these two conceptions of their businesses will influence their environmental 'and social actions. During the next 10-20 years western industry will be subject to a drop in the growth of a more highly educated labour force and to the emergence of holistic economics, new national goals, and a new ecological perspective. The profitability of the mining industry may therefore be influenced by the human side of its business to a greater degree. The increasing human, social, and environmental responsibilities can be discharged by improving the miner's equipment; by learning to look at situations through the eyes of all those involved; by developing common 'languages' which governments and the public can understand; and by mediating where feasible on the international scene.

Jan 1, 1978

By W. E. Forsythe

WHEN measuring ordinary temperatures, the instrument is generally placed in very close contact with the body the temperature of which is desired. However, if the temperature of the source is continually raised, a point is soon reached where no known substance will, in general, remain constant in any of its temperature-measuring properties if placed in direct contact with the source. Also, it is occasionally necessary to measure the temperature of a source that 'is so small or so situated that it would be very hard to bring the measuring instrument into direct contact with the source. When these conditions exist, advantage is taken of the well-known fact that all bodies, when at sufficiently high temperatures, send out radiation in amounts readily measurable. This radiation has been found to be related to the temperature. The temperatures of very hot bodies have probably always been judged by the color, or the brightness, of the light given off. With practice, one can estimate probably within 50° to 100° C. of the correct value. However, if judgment is left to the eye alone, very much larger errors are sometimes made, due to

Jan 9, 1919