Search Documents

By Horace Williams

IN VIEW of the frequent occurrence of petroleum in other parts of the world, it seems odd that so large an area as is contained within the borders of Brazil should be without this product. This apparent deficiency may be due, however, to our ignorance of the regions in which-it, may exist. In some places, indications point to the probable existence of petroleum in ages gone by; and while the presence of petroleum pools may be problematic, in several regions conditions not unfavorable to their occurrence exist. Yet, Brazil has enormous oil resources in the rich oil-shales in different parts of the country. Many of these shales are very rich and only suitable processes for the extraction of the oil are lacking. At the present time, only a few small experimental plants are producing oil by distillation from these shales. These plants have been the subject of recent investigations by the Geological and Mineralogical Survey, a. pre-liminary report of which is in the hands of the printer. The only regions where studies have not been made are the upper Amazon, the Acre, the Rio Negro, and the Peruvian frontier, which really seems to be the most promising field for, explorations of any in the country. In the vast plateau region of the interior north of the 20th parallel of latitude, granites, gneiss, mica schists, and, very old metamorphosed sedimentaries predominate. Later, sedimentaries occupy a minor position and, where found in the interior, represent a thin veneering resting on the older rocks. At several places near the coast they have a greater development and contain considerable beds of oil-shale and may, in some cases, offer conditions favorable for the occurrence of oil. Such deposits are found in the Permian rocks of central-and southern Maranhão; in the Tertiary and Cretaceous beds along the coast of Alagôas Sergipe, Bahia, and perhaps farther south in Espirito Santo; and in the Parahyba embayment north of Cape Frio and in the interior Tertiary basin of eastern Sao Paulo.

Jan 9, 1920

By W. W. Vaughn, R. H. Barnett, E. E. Wilson

Soon after the search for uranium ores on the Colorado Plateau began in earnest, thousands of feet of drill core ranging from 1 1/8 to 2 1/8 in. diam became available for study. Although significant advances had been made in the technique of quantitative gamma-ray borehole logging, instrumentation was in the development stage, and complete reliance could not be placed on gamma-ray logs alone to interpret quantitatively the meaning of radioactivity in a drillhole. A method that would be faster than chemical analysis and still give reproducible and reliable results for various drill core sizes was desirable to provide additional information on the enormous footage of drill core being accumulated. A solid phosphor scintillation drill core scanner was designed and constructed. Basically the instrument was developed to measure radiation from a drill core which would not be clearly recorded by a gamma-ray logger using a Geiger tube as the sensitive element. Such data would be beneficial in constructing isorad maps to delineate ore-bearing zones. A calibration in the range 0.01 to 0.1 pct eU3O8 was provided; above 0.1 pct eU3O8 gamma-ray logs were available and were being used to calculate grade and tonnage of ore reserves. The core scanner, however, has been used to estimate equivalent uranium content of ore-grade materials containing as much as 2.2 pct eU308 with an accuracy of ±10 pct, the sample being in the form of a BX drill core. Actually, an apparent calibration of eU308 vs counts per unit time is a straight line with a slope that is a function of the sensitive element and the geometry of the counting assembly. A true calibration that will show the expected departure from a straight line is due principally to the random nature of the pulse from a radiation source and the nonlinearity of the electron circuitry.

Jan 6, 1959

By Leonard B. Griffiths

In a recent communication, Smith and Wood described some results of 800°C compression/creep tests on WC-12 wt pct Co alloys in which plastic flow in the WC particles was believed to have occurred. The deformation observed in the WC particles was found to be a function of the rate of loading. The authors suggested that their data constituted support for the Ansell6-Lenel theory of yielding in dispersion-strengthened alloys. I do not agree with this interpretation since the Ansell-Lenel theory does not apply to the type of alloy in question. In this alloy, the dispersoid is present to the extent of about 80 vol pct. Even where there is no continuous skeleton, which apparently is the case in this instance, the simple fact is that nearly all of the load is carried elastically by the stronger material (wc).7 The constraint imposed upon the matrix, by virtue of the differences in Young's modulii and Poissons ratios, severely limits the stress level to which it may be subjected (assuming that the interfaces remain intact). If one allows for the constraint and then performs the same computation as in Smith and Wood, one finds that the stress on a WC particle is about 4 x 105 psi. This is about 21/2 times lower than the predicted fracture stress for WC. I would completely agree with the final paragraph of Smith and Wood, namely, that loading rate is of considerable significance. However. a more likely interpretation of their data is, I submit, that in the absence of stress relaxation (by secondary slip or climb) those WC-Co interfaces subjected to a normal tensile stress begin to fail. Once this occurs, the stress distribution will change rapidly and "premature" fracture of the WC then becomes quite probable. Tne serrated edges shown in Fig. 1 may very well be fine, interface fissures.

Jan 1, 1970

By Henry Louis

The present paper comprises two parts, which have but little con nection with each other. The first is practically a continuation of the investigation on the specific gravity of gold liberated by means of acids from its alloys, on which subject I had the honor of presenting a brief note to the Institute in 1893 (Trans., xxii., 117); the second describes a series of experiments on the behavior of amorphous gold under the action of heat. By the kindness of Prof. W. C. Roberts-Austen, C.B., F.R.S., chemist to the Royal Mint, I have been permitted to conduct these experiments in the mint assay-office, all the splendid resources of which institution were freely placed at my disposal. I desire at the outset to express my obligations to Prof. Roberts-Austen and to all the staff of the mint assay-office for their kind assistance at all stages of my experiments. I.—The Specific Gravity of Gold in Alloys. In the note already referred to, I published my discovery that the gold left on dissolving out the silver from an alloy of gold and silver (which I shall here term " residual amorphous gold ") has a higher specific gravity than ordinary molten gold. I also pointed out that I had worked on very small quantities of material and with balances and weights on the accuracy of which I could not implicitly rely, and that in so far my numerical data were inconclusive, although I had but little doubt of the correctness of the broad fact. The experiments now recorded were made under the most advantageous circumstances and with various refinements. Particularly, I found that the ordinary form of specific-gravity bottle was responsible for several small sources of error; and I accordingly designed an improved form (Journal of the Society of Chemical Industry, April 30,1894, vol. xiii., p. 322), which I used for this work. The

Jan 1, 1895

Discussion of the paper of IRVING A. PALMER, presented at the Salt Lake meeting, August, 1914, and printed in Bulletin No. 91, July, 1914, pp. 1447 to 1460. L. S. AUSTIN, Salt Lake City, Utah.-With the union of the Guggenheim interests and the American Smelting& Refining Co. in 1900, competition among the lead-smelting companies appeared to have been largely eliminated. This condition prevailed for but a short time, owing to the erection of smelteries by competing companies. Naturally, as competitors, the older companies endeavored to keep improved methods to themselves, not realizing, it would appear, that such knowledge could never be bottled up, but would drift into the common field of practice. Of late it has begun to be felt that more is gained than lost by adopting a franker and more open policy. The line, however, is drawn in. giving details of costs, which, fully known, it is felt, would be taken advantage of by a rival. As Mr. Palmer says, steady and substantial progress has been made, and latterly, I may add, the improvements have been radical. Sintering by the Huntington-Heberlein method or with Dwight-Lloyd machines has effected an important saving over reverberatory roasting, the cost being, say, 50 to 75c., as compared With $2 per ton by the older method. Moreover, the .large use of a sintered product has resulted in doubling blast-furnace tonnage. However, the change has not been an unmixed blessing, as in the machine roasting little time can be given to the breaking up of the blende, and it has been impossible to decompose largely the zinc sulphide, so detrimental in later blast-furnace treatment. The satisfactory roasting of the blende is still an unsolved problem. Nor is this all. For the best reduction it has been found that a part of-the change should be crude (unsintered) ore, indicating that the already fused material is only too ready to change to slag, thus lessening the opportunity for better reduction.

Jan 11, 1914

It is probable that the first commercial production of coal in Ohio was for the supply of Wheeling, before mines were opened at that place. This coal came from Pipe Creek in Belmont County,l where the seam was exposed a short distance above the river. This movement could not have lasted more than a few years, because coal was being mined at Wheeling in 1818, and probably before that.2 Mining began in Tuscarawas County in 1810 and in Perry County in 1816, and has been followed steadily since then. In the eighteen twenties the Pomeroy field in Meigs County, Jackson County, and the northern Ohio field in Summit County commenced production. All of the early data available are given in Table 57. No early official reports were made, but after 1859 the Secretary of State published statistics of production, admittedly inaccurate, by counties, and under various officials these have been continued to the present day. Ohio has never published statistics about coal in smaller units than the county; no reports of individual properties have ever been collected. The period from 1800 to 1885 includes the opening of practically all of the coal fields of the state, although those of eastern Ohio were not large producers at its end. During this time the use of raw block coal in blast furnaces had begun and ended, and at the end, coke was nearly the universal fuel for this purpose. Much of the coal traffic on the Ohio River and its main tributaries originated in the necessity of a fuel supply for Cincinnati and other down-river cities. This traffic started in 1794, and few records of it are available until many years later; in 1846 records of the movement to Cincinnati began and have been maintained with increasing thoroughness, and represent one of the most complete records of such a traffic extant anywhere. As these data show the originating fields of most of the coals used there, the available figures to 1885 have been collected in Table 16.

Jan 1, 1942

By Charles L. Mantell, P. P. Napolitano

High-purity tellurium oJ semiconductor grade may be prepared by a combination of electrowinning from tellurium oxide, electrorefining and controlled atmosphere melting, as detailed in the paper. SEMICONDUCTOR devices such as transistors and rectifiers depend upon extremely pure forms of silicon, germanium, and selenium. Although tellurium is chemically related to these elements, it has not been studied as a semiconductor because commercial forms are too impure. Highly purified tellurium would be an interesting starting point for a study of its solid-state characteristics. Tellurium shows a greater electrical conductivity in the direction of the helices or chains forming the crystals than at right angles to the chains, and thus is a semiconductor. Unlike selenium, the conductivity is only slightly increased by exposure to light. Impurities such as Ag, Cu, Au, Fe, Sn, As, Sb, Bi, Br, and I provide accepters and make extrinsic tellurium of the P type. So far, however, no elements have been found which, when introduced, would act as donors. Small amounts of tellurium dioxide enormously increase the thermoelectric power. Many extremely pure metals have been made by electrolytic refining or electrowinning procedures. Tellurium forms compounds in a number of valences, as indicated in Table I. The physical properties given in Table II do not show any unusual conditions which would interfere with the formation of elec- trodes, or the deposition of the metal on a cathode. Tellurium dioxide could be obtained in relatively high purities of 98 pct TeO2 or better at reasonable prices. Tellurium dioxide is soluble in caustic to form tellurites, which are conductive, ionizable, and from which tellurium metal may be deposited at a cathode. Preliminary solubility tests to saturation of tellurium dioxide in approximately 10 pct sodium hydroxide gave the results of Table III. The temperature range is a practical one for electroplating. Electrochemical test facilities were set up and these met the operating conditions of Table IV. For a determination of purity of deposits, there was available a Jarrell Ash Co. quantitative emission

Jan 1, 1964

By Alphonse Hennin

It is well known that under certain conditions ammonia is found in the gas produced by the distillation of coal. Until recently it was held, and many still believe, that this ammonia exists in the coal, and is a natural product of the destructive distillation, varying in percentage, like the other products, according to the nature of the coal, but not formed synthetically beyond that limit. This opinion is in contradiction with well-established facts concerning the formation of ammonia from the elements of the coal. If any ammonia exists as such in the coal, the quantity is insignificant. The purpose of this paper is to explain the theory of the formation of ammonia during distillation, and call the attention of the members of the Institute to its application in connection with the production of heating-gas for metallurgical purposes, etc. For many years little or no importance was attached to the presence of ammonia in coal-gas. It was deemed by the gas-manufacturers an undesirable product of the process, as one of the impurities to be removed; and no attempt was made for its recovery. Not until its practical extraction and utilization was found possible, did scientists commence to investigate the question. Little was known about the nitrogen of the coal, and still less about the reactions leading to its transformation into ammonia. A. W. Hofmann, I believe, was the first to establish a relation between the percentage of nitrogen in the coal and the proportion of ammonia in the coal-gas. As early as 1863 he pointed out that, in dry distillation, such as is practiced in the manufacture of illuminating-gas, only one-third of the total nitrogen in the coal is liberated, two-thirds remaining in the coke. It is no longer possible to doubt that the ammonia is a synthetical product, resulting, under certain conditions, from the combination of the,elements of the coal. Chemistry teaches that ammonia is formed in many cases when

Jan 1, 1893

By Gregory J. Comstock

There is a growing interest in the possibilities presented by the manipulation of metal powders, which justifies an attempt to summarize their character and potential value. A summary of this kind presents an opportunity for making a classification of metal powder products into several general types. Our present knowledge of the finer and more abstract aspects of many of the principles involved in metal powder technique is extremely limited. Any conclusions as to the ultimate value of the process will, therefore, for the present at least, be of doubtful value unless they are substantiated by its products. The number of such products is increasing. A study of their diverse and unusual characteristics; an examination of the methods by which they are made, and a consideration of the reactions that take place during their fabrication, in so far as we can define them, should afford as good an evaluation of this interesting development as it is possible to make at this time. A critical study of this kind results in a formidable list of special attributes, which apparently are characteristic of applied powder metallurgy. A comparison of these special effects with the end products and well defined limitations of the melting and casting process indicate that often they may very well be considered as being special advantages. They are subject, of course, to certain not as yet so well defined limitations of their own. Based on current products only, a necessarily condensed summary of the more striking special attributes of the metal powder process follows. Manipulation of Highly Refractory Metals The powder process presents a means of manipulating highly refractory metals, which cannot be cast and formed in the usual melting and casting process. Tungsten, molybdenum and tantalum are the classic examples of the adequacy of the metal powder process for meeting unusual conditions of this character. The development and application of these metals by means of it, and their importance in the electrical

Jan 1, 1938

By A. S. Nowick, A. E. Roswell

Anelastic measurements of atomic mobility in an Ag-Zn substitutional solid solution, make possible a study of the rate of decay of lattice defects frozen into the alloy by quenching. A WIDE variety of experimental evidence has accumulated recently in support of the belief that atomic mobility or diffusion in face-centered cubic lattices occurs principally through the movement of lattice defects, as contrasted to a mechanism by which two or more atoms directly exchange lattice positions. The most direct evidence, summarized in a recent review,' includes the Kirkendall-effect measurements and anelastic measurements on quenched alloys. Theoretical calculations' have focused attention on the lattice vacancy as the defect probably responsible for diffusion in the common metals. Later calculations3 have also shown the possible importance of combined pairs of vacancies in producing diffusion. The only defect that has been considered seriously, in addition to the vacancy and combination of vacancies, is the "interstitialcy" (an atom which has left its normal lattice position and entered an interstitial position) ; the calculated energy of formation of an interstitialcy in a close-packed lattice is too large to permit a reasonable probability for the occurrence of this defect In view of these calculations it may be tentatively concluded that the defects producing atomic movements are single or multiple vacancies. Anelastic measurements of atomic mobility in substitutional solid solutions provide a valuable method for the study of lattice defects. By means of this method it was first demonstrated' that defects may be frozen into a lattice by rapid quenching from high temperatures. (It was subsequently shown6 that resistivity measurements may also be capable of detecting the presence of frozen-in defects.) A summary of the principles involved in these anelastic measurements will now be presented. The anelastic method is based on a relaxation phenomenon in substitutional solid solutions, first discovered by Zenera in a brass and subseauentlv investigated extensively in a series of Ag-zn solid solutions.' This relaxation effect may be observed in the usual way either dynamically, as a peak in

Jan 1, 1954

By H. E. Williams

In view of the frequent occurrence of petroleum in other parts of the world, it seems odd that so large an area as is contained within the borders of Brazil should be without this product. This apparent deficiency may be due, however, to our ignorance of the regions in which it may exist. In some places, indications point to the probable existence of petroleum in ages gone by; and while the presence of petroleum pools may be problematic, in several regions conditions not unfavorable to their occurrence exist. Yet, Brazil has enormous oil resources in the rich oil-shales in different parts of the country. Many of these shales are very rich and only suitable processes for the extraction of the oil are lacking. At the present time, only a few small experimental plants are producing oil by distillation from these shales. These plants have been the subject of recent investigations by the Geological and Mineralogical Survey, a preliminary report of which is in the hands of the printer. The only regions where studies have not been made are the upper Amazon, the Acre, the Rio Negro, and the Peruvian frontier, which really seems to be the most promising field for explorations of any in the country. In the vast plateau region of the interior north of the 20th parallel of latitude, granites, gneiss, mica schists, and very old metamorphosed sedimentaries predominate. Later, sedimentaries occupy a minor position and, where found in the interior, represent a thin veneering resting on the older rocks. At several places near the coast they have a greater development and contain considerable beds of oil-shale and may, .in some cases, offer conditions favorable for the occurrence of oil. Such deposits are found in the Permian rocks of central and southern Maran-hao; in the Tertiary and Cretaceous beds along the coast of Alagsas Sergipe, Bahia, and perhaps farther south in Espirito Santo; and in the Parahyba embayment north of Cape Frio and in the interior Tertiary basin of eastern Sao Paulo.

Jan 1, 1921

By Gregory J. Comstock

There is a growing interest in the possibilities presented by the manipulation of metal powders, which justifies an attempt to summarize their character and potential value. A summary of this kind presents an opportunity for making a classification of metal powder products into several general types. Our present knowledge of the finer and more abstract aspects of many of the principles involved in metal powder technique is extremely limited. Any conclusions as to the ultimate value of the process will, therefore, for the present at least, be of doubtful value unless they are substantiated by its products. The number of such products is increasing. A study of their diverse and unusual characteristics; an examination of the methods by which they are made, and a consideration of the reactions that take place during their fabrication, in so far as we can define them, should afford as good an evaluation of this interesting development as it is possible to make at this time. A critical study of this kind results in a formidable list of special attributes, which apparently are characteristic of applied powder metallurgy. A comparison of these special effects with the end products and well defined limitations of the melting and casting process indicate that often they may very well be considered as being special advantages. They are subject, of course, to certain not as yet so well defined limitations of their own. Based on current products only, a necessarily condensed summary of the more striking special attributes of the metal powder process follows. Manipulation of Highly Refractory Metals The powder process presents a means of manipulating highly refractory metals, which cannot be cast and formed in the usual melting and casting process. Tungsten, molybdenum and tantalum are the classic examples of the adequacy of the metal powder process for meeting unusual conditions of this character. The development and application of these metals by means of it, and their importance in the electrical

Jan 1, 1938

By Robert Linton

IN 1898, Joseph L. Giroux and J. A. Snedaker organized the Pilot Knob Copper Co. and began developing the Pilot Knob mine at Kimberly, Nev., for high-grade copper ores, carrying good gold and silver values that the formation had disclosed. At that time the nearest railroad was over 150 mi. distant. The high-grade ores did not prove to be extensive at this point-at least to the depth. (240 ft.) to which the work was carried-but development of neighboring claims indicated extensive deposits of sulfide porphyry ore of concentrating grade lying at shallow depth, and deeper deposits of direct-smelting oxidized ores occurring in limestone near the limestone-porphyry contact. The properties passed through the hands of several organizations, with only meager development, until acquired in 1913 by Consolidated Coppermines Co., whose holdings now comprise 3480 acres of mining claims in the Robinson district. Since that time development has been prosecuted more actively; and for the purpose of determining the most efficient and economical method of treating the ores, considerable testing work has been done during the past three years, both in the laboratory and in actual mill operations. At first, the shipments were of ore high enough in grade to be profitable even with the long wagon hauls to the railroad and prevailing freight and smelting charges. In 1905, a blast furnace and a concentrator were erected at Kimberly. On account of insufficient ore supply, the blast furnace was never blown in and later was dismantled. The concentrator as originally equipped wag operated for only about two months, both because the ore supply was not sufficient and because gravity concentration did not yield satisfactory extraction. The location and arrangement of the mill further entailed high operating costs. In 1908, the Nevada Consolidated Copper Co. began to mill successfully, on a large scale, its sulfide porphyry ores, which are similar in character to the adjacent Coppermines ores. After that time, all of the ores and concentrates produced by Coppermines Company were

Jan 8, 1920

By Glenn A. Keep

THIS paper is not an announcement of the successful conclusion of the Cerro de Pasco Copper Corporation's pacos-pyrite problems, but merely a description of the commercial-scale, intermittent-roasting operations conducted by the writer, J. H. Lucas and others of the staff. It was prepared by request, for presentation at the February meeting of the Institute. The results obtained in Peru confirm the 1-ton-a-day experiments completed about three years ago at Kearny, N. J. by C. C. Gordon and Mr. Lucas, where it was first demonstrated that a mixture of about 80 per cent. pacos ore with 10 per cent. pyrite ore and 10 per cent. salt could be roasted intermittently in a small 1-ton-a-day Holt-Dern furnace without extraneous fuel, producing porous calcine that could be leached rapidly. Mr. Keep and his staff, by successfully introducing improvements in the construction of the commercial furnace and in their handling of material, have established beyond doubt a low cost for roasting. The other steps in the process of treating pacos and pyrite ores have not as yet been demonstrated as sufficiently conclusive to warrant their acceptance for a permanent plant. Cerro de Pasco Ores The ores of the Cerro de Pasco Copper Corpn. at Cerro de Pasco, Peru, are situated at an altitude of 14,000 ft. The town and mines are served by the Cerro de Pasco Railroad, which operates between Cerro de Pasco and Oroya, the site of the company's copper and lead smelters. Table 1.—Average Analysis of Cerro de Pasco Ores Pacos Ore Pykite Ore Silver, oz............................................... 10.3 12.0 Gold, oz................................................ 0.007 0.01 Lead, per cent........................................... 1.7 1.8 Copper, per cent......................................... 0.19 0.27 Zinc, per. cent........................................... 1.4 1.02 Iron, per cent........................................... 13.4 34.45 Silica, percent.......................................... 61.8 24.5 Alumina, per cent....................................... 2.5 0.62 Lime, per cent........................................... 1.5 0.20 Manganese, per cent..................................... 0.42 0.09 Sulfur, per cent,.......................................... 1.1 34.2

Jan 1, 1929

By J. J. Sense

10.2-1. Equipment Scheduling. In any earth-moving operation, more profit may be earned or lost by equipment scheduling than by any other single facet of the project. Many now-defunct earth movers would have survived the cost-profit squeeze had they followed an efficient, cost saving, equipment scheduling program. The ideal program would have every item of the equipment fleet working all of the time. In practice for many obvious reasons, principally mechanical conditions, operating conditions, and human nature-this ideal situation is not possible. The cost-conscious organization strives to keep as many pieces of equipment of the fleet working efficiently as much of the work day as possible. Operating efficiency requires the minimum equipment to move the predetermined tonnages in the prescribed period of time. In the case of a shovel-truck operation this would mean the scheduling of the minimum shovel and truck shifts to excavate and transport the necessary tonnage to the processing plant or waste dump. To accomplish this goal, the operator must work from the predetermined production established by the requirements of the plant, stripping ratio, mine plan, etc. This production schedule may be in terms of tons or yards per year, per month, or per hour, but must eventually be translated into tons or yards per ma- chine per unit of time. In this regard, the reader is referred to Sections 8.0, Excavation and Loading, and 9.0, Haulage and Transportation. The trend to larger and faster, and as a result more costly, equipment requires that the operator consider every possibility to keep the equipment operating around the clock, seven days per week. In some areas seven day operation may not be feasible economically, because of premium pay for Sunday work. Mine labor agreements are generally written without premium pay penalties for weekend work, and such scheduling is possible and most often desirable.

Jan 1, 1968

By E. L. Larison

DURING the early years of the present century a notable interest appeared in American industry in the matter of recovering and render-ing profitable byproducts of manufacturing operations. Among the byproducts of reduction of sulfide ores in many plants large amounts of sulfur dioxide gas were available. In certain instances the concentration of SO2 in the gases evolved was, or could be made, sufficient to make them suitable for manufacturing sulfuric acid. At the Anaconda Reduction works such a condition existed. Large tonnages of copper concentrate were being roasted and the roaster gases were available and suitable as a source of sulfuric acid. Earlier work on a large scale at Martinez, Calif., and in the Ducktown region, Tennessee, had shown the feasibility of manufacturing sulfuric acid from the SO2 contained in gases arising from the reduction of copper sulfide ores. In California and Tennessee the acid found a ready market in manufacture of fertilizers, while the situation regarding disposal of the sulfuric acid was quite different at Anaconda. No local use for acid existed, and a commodity of such low value could not stand freight charges to consuming centers. There was a very large accumulation of sand tailings from the gravity concentration mill below the plant at Anaconda. This material, made by the comparatively crude methods in use up to about 1915, contained about 13 lb. of copper per ton, largely as sulfide minerals. In 1912 serious research work toward recovery of this copper was instituted and after about two years of laboratory and pilot-plant development, a process for accomplishing it was perfected. This process involved roast-ing the sand tailings, leaching the roasted tailings with sulfuric acid, and throwing out the copper by passing the solutions over scrap iron. Under this plan each ton of sand required the introduction of about 70 lb. of 60° Be. sulfuric acid.

Jan 1, 1934

By H. M. Wolflin

SOMEWHAT more than a year ago the writer collected some extensive notes on metal-mine fires and a paper on metal-mine fire prevention and fighting, a summary of these notes, was hastily pre-pared, with the assistance of G. Chester Brown, chief mining engineer, Industrial Accident Commission for the National Safety Council meeting. This summary, which is admittedly incomplete, is submitted in the hope that it will evoke some discussion that may result in a reduction in metal-mine fire hazard along the line. To accomplish such a reduction does not require the application of complicated scien-tific data. The use of just a little care, a small amount of thoughtfulness and a bit of common sense will work wonders. UNDERGROUND FIRE FIGHTING There may be some interest in a short list of con-clusions of a rather general nature that were reached in connection with some recent mine-fire fighting opera-tions. No effort has been made to cover the field; the items have been jotted down loosely, and very hastily, in the order in which they occurred to the writer. Originality is claimed for, only a few of them. 1. Temperature readings and analyses of mine-air samples, systematically taken, are invaluable aids to effective metal-mine fire fighting and recovery opera-tions. The analysis of the return-air samples fre-quently gives a surprisingly accurate indication of conditions existing underground. 2. Employees must be thoroughly trained in the use, of mine rescue apparatus, because a relatively slight difference in the amount of training makes a vast difference in the amount of work they can per-form under oxygen. In general, slender, wiry men make better apparatus men than those of heavy, more muscular physique, although there are frequent excep-tions to any such general statement. 3: Surprisingly high temperatures, up to 165° F. or 170° F. pan be endured for short periods by wearers of mine rescue apparatus if the air is dry, but lower temperatures, 135° to 140° F. are almost unbearable if the air is very moist.

Jan 2, 1922

By Gregory J. Comstock

THERE is a growing interest in the possibilities presented by the manipulation of metal powders, which justifies an attempt to summarize their character and potential value. A summary of this kind presents an opportunity for making a classification of metal powder products into several general types. Our present knowledge of the finer and more abstract aspects of many of the principles involved in metal powder technique is extremely limited. Any conclusions as to the ultimate value of the process will, therefore, for the present at least, be of doubtful value unless they are substantiated by its products. The number of such products is increasing. A study of their diverse and unusual characteristics; an examination of the methods by which they are made, and a consideration of the reactions that take place during their fabrication, in so far as we can define them, should afford as good an evaluation of this interesting development as it is possible to make at this time. A critical study of this kind results in a formidable list of special attributes, which apparently ate characteristic of applied powder metallurgy. A comparison of these special effects with the end products and well defined limitations of the melting and casting process indicate that often they may very well be considered as being special advantages. They are subject, of course, to certain not as yet so well defined limitations of their own. Based on current products only, a necessarily condensed summary of the more striking special attributes of the metal powder process follows. MANIPULATION OF HIGHLY REFRACTORY METALS The powder process presents a means of manipulating highly refractory metals, which cannot be cast and formed in the usual melting and casting process. Tungsten, molybdenum and tantalum are the classic examples of the adequacy of the metal powder process for meeting unusual conditions of this character. The development and application of these metals by means of it, and their importance in the electrical

Jan 1, 1938

By Robert W. Hunt

PeRhaps of all the scientific economic questions which have been claiming the attention of capitalists, metallurgists, manufacturers, directors of public utilities, and the general public of America, during the last few years, none have been of more importance than the one relating to the wear and safety of steel rails. The discovery of the Bessemer process made possible modern railway development. In that growth, as has generally happened in all progressive movemeuts, all its departments have not remained equally balanced. Iron rails permitted the construction of roadways for the passage of power-driven vehicles. In time the speed and weight of such carriages proved too much for the wearing-qualities of the rails, and the limit of railway capacity seemed to have been reached. Bessemer made his invention, which was soon perfected and developed, especially as related to steel rails, and thereby increased the limit of capacity, and vastly greater railway progress was made pgssible. The Siemens-Martin open-hearth process followed, and was later supplemented by the Thomas-Q-ilchrist basic improvement. For a time the Bessemer steel rails of commerce were more than equal to all that was asked of them, but this did not long continue, as evidenced by the records in our Tansactions. Revolutionary changes occurred in the industrial world, and in no part of it more than in steel-rail manufacture. Great and powerful commercial combinations were made, whose financial resources made possible the supplanting of the then most efficient blast-furnaces, steel-works, and mills, by others of theretofore unimagined capacity. Old traditions and practices of steel-making were wiped away, and, in too many cases, output was apparently the chief aim, with the result that much dissatisfaction with the wear and safety of rails was felt by railway officials, and the general public was concerned as to its safety when traveling. The climatic conditions of the winter

Jan 1, 1913

By L. I. Cothern

THE introduction of mechanized mining has created a demand for long working faces. It has also prompted mining men to contest the old theory that longwall methods can be used only where roof conditions are ideal and where pack-wall material is plentiful. "Longwall" as used in this paper means "modified longwall," "semi-longwall," or any of the various "wall" or "long-face" methods of mining. Many mines are now using long conveyor faces that differ only in their methods of development, types of roof support and method of loading coal onto the conveyor. Some types of longwall operations are being carried on successfully under conditions heretofore considered impossible by men experienced in longwall mining. With possibly one or two exceptions, long-face methods in Alabama are a direct result of the need for lower mining costs. The advantages over room-and-pillar systems were clearly expressed in an article by Messrs. Fies and Lacy of the DeBardeleben Coal Corporation1 as follows: (1) increased tonnage per miner; (2) increased percentage of lump coal; (3) reduction in cost of development; (4) elimination of the cost of room yardage; (5) reduction in the cost of haulage, from ability to use larger cars; (6) reduction in the cost of machine cutting; (7) reduction in cost for tracks; (8) reduction in the cost of deadwork; (9) reduction in the cost of supervision. An attempt on the part of the operator to gain these, advantages by changing from room-and-pillar to longwall requires considerable courage, and credit should be given to those men who have done their bit to meet the competition of rival fuels. The initiatory problems to be solved are in reference to: (1) retreating or advancing system, (2) length of wall, (3) method of roof support, (4) method of entry development, (5) type of conveyor or loader, (6) hand vs. machine loading (onto conveyors), (7) hand vs. machine loading in entries, (8) control of roof pressure,

Jan 1, 1940