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By David G. Chedgy

The Meadow River No. 1 preparation plant, owned by Sewell Coal Co. which is a subsidiary of the Pittston Co., was commissioned in the spring of 1974. A survey of the environmental noise levels was conducted, and the dominant noise sources identified. An engineering program was initiated to reduce the prevailing levels to a point that the operator's exposure would be within compliance with the MESA regulation for ear protection. The program was continued until compliance was achieved and the attenuation factors for each abatement device recorded. The highlights of this program will be presented with a discussion of the practicality of the devices utilized.

Jan 1, 1977

Duval Corporation, the copper -producing subsidiary of Pennzoil United, Incorporated, operates two plants south of Tucson, Arizona: Esperanza and Sierrita. The newest, the Sierrita mine and mill, came into full production in 1971 at a rate of 72,000 tpd (now 87,000 tpd) which at that time made it the largest designed copper plant in the world. In 1968, the largest milling units then available were selected; these included fourteen 16$ ft by 19 ft long ball mills (5 m by 5. 9 m), each equipped with a 3,000 hp motor. The primary crushing plant contains two 60 in. by 89 in. Allis- Chalmers gyratories; each is constructed for two-side dumping by 120- and 150-ton trucks. Access to the maintenance areas to service the drive motors, eccentrics, apron feeders, and speedup conveyor is through hatches between the crushers. This area also contains a good- sized elevator and a stairway. The rather shallow dump pocket, the 300 -ton crushed ore pocket, and the overall design make for a fine, compact arrangement for two 60 in. crushers installed in a total height of 89 ft (27. 13 m) from dump level to top-of-concrete at the lowest level beneath the collecting or speedup belt. This efficient layout is reflected in the short changeout time for mantle and concaves (8 and 30 hours respectively) and the low crushing cost of $0.0416 per ton (first half of 1975). The crushers are installed on 64 ft (19.5 m) centers (Bougainville and Palabora, both with 54 in. crushers, are 55 and 43 ft or 16.76 and 13. 1 m respectively). The switchgear room is located between the truck dumping positions on one side of the installation and the hydroset units on the other side, with dust collecting equipment mounted over the latter. Protection of these units from rocks falling from the trucks is provided by concrete walls. Truck dumping is controlled from a central 25 ft high (7.6 m) control room, which permits fine observation of operations. Removal of oversize boulders from the dump pockets is done with a hydraulic grapple or a rock hook or sling attached to the auxiliary crane hook. Spare mantle stands and a maintenance room with a zinc melting furnace are located at one end of the surface facilities. The maintenance room is equipped with an access door for the crane, which is equipped with 80- and 20-ton hoists. The two 84 in. (2. 135 m) apron feeders receiving the 6 in. (152 mm) crushed rock discharge onto a 72 in. (1. 83 m) collecting and wear belt operated at a speed compatible with the 60 in. (1.524 m) takeaway belt running at a speed of 630 fpm (192 mpm). This belt feeds a 54 in.

Jan 1, 1978

By John W. Tieman

Research on processes to remove sulfur oxides from flue gas has been in progress for many years. Pioneers in this field were the British who, in the early 1930's, installed a full-scale flue gas scrubbing unit on a 120 MW boiler using alkaline water from a Thames estuary plus chalk. Since that time, various methods have been studied by many investigators. Federal laws covering air pollution started with the 1955 Air Pollution Control Act. With the advent of the Air Quality Act of 1967, and subsequent publishing of criteria and available technology for control of sulfur oxides in January 1969, the clamor for information on commercially available control techniques to remove sulfur from fossil fuels has rapidly increased.

Jan 8, 1972

By M. J. Hart, E. C. McDowell

There are no formulas that guarantee success when obtaining zoning approval for mineral aggregate mining. Local land use decisions often represent the most controversial issues faced by a community. Public awareness, concern, willingness to get involved, sensitivity to the environment and, probably most important, fear of change only begin to describe the atmosphere in which local land use decisions are made. The public hearing process is quasi judicial, adversarial, and unfortunately, not designed for resolution of disputes. It is not difficult to see the need for an alternative to present methods. Hopefully, some day there will be a process that will do away with or at least minimize unnecessary, unproductive, and unmanageable community conflicts.

Jan 1, 1986

By Charles Holland

MINERS have observed for many years that as pillars are removed in mining operations the pillar adjacent to those mined out frequently shoes evidence of being compressed. Although this has been known for a long time, little or no information is available concerning how far from the mining area the pillars are affected in this manner, or how great is the magnitude of the compression, or concerning the manner or char-acteristic way in which the compression acts, as the mined-out area approaches the pillar under consideration. The writer made a study of pillar action in the Mona mine of the Arkwright Coal Co., partly to get some quantitative data on the deformation of coal-mine pillars. The study was not completed but it seems best to present the information that was obtained.

Jan 1, 1937

By Herbert Clark Hoover, Lou Henry Hoover

IN the last book I have explained the methods of delimiting- the meers along each kind of vein, and the duties of mine officials. In this book1 I will in like manner explain the principles of underground mining and the art of surveying. First then, I will proceed to deal with those matters which pertain to the former heading, since both the subject and methodical arrangement require it. And so I will describe first of all the digging of shafts, tunnels, and drifts on venae profundae; next I will discuss the good indications shown by canales2, by the materials which are dug out, and by the rocks ; then I will speak of the tools by which veins and rocks are broken down and excavated ; the method by which fire shatters the hard veins ; and further, of the machines with which water is drawn from the shafts and air is forced into deep shafts and long tunnels, for digging is impeded by the inrush of the former or the failure of the latter ; next I will deal with the two kinds of shafts, and with the making of them and of tunnels ; and finally, I will describe the method of mining venae dilatatae, venae cumulatae, and stringers.

Jan 1, 1950

By George Rice

WITH so tremendous a subject, an attempted review of the coal situation of the world in a short talk must necessarily be of a sketchy character. It is hardly necessary to tell a body of engineers that had it not been for nature's gift of coal the material side of modern civilization would never have reached its present status. On the other side, it is regrettable that it was a byproduct of coal, T. N. T., which made possible Germany's initial success in this war, because that country had an enor-mous development of manufacturing plants that could be immediately utilized to make this destructive agent. One sometimes hears the casual remark that when the coal of the world is exhausted we shall use electricity; but, of course, electricity is ordinarily only a means of transforming and transmitting energy derived from fuel or water power, and chiefly from coal. It is true, we have much undeveloped water power, but it is more or less remote from the centers of industry; and when all shall have been developed it will not begin to supply the power requirements of the world. It is, however, reasonable to expect that before the world's supply of coal shall be exhausted, methods will have been discovered of harnessing other forces of nature, such as the tides, or the energy emanating from the sun. Petroleum and natural gas naturally come to mind, but the days of both, as fuel, appear to be numbered, although the products of petroleum, if economically used, doubtless will be available for internal-combustion engines, automobiles, trucks, and boats. for a long time, provided the reckless use of crude petroleum as an ordinary fuel is stopped. The products of petroleum are too valuable to mankind for such waste to be permitted. The civilization of the world, therefore, appears to rest, and, so far as can be seen, will indefinitely continue to rest, upon coal.

Jan 1, 1918

By R. W. Raymond

Richard Pennefather Rothwell, was born May 1, 1836, at Oxford, Upper Canada (now the province of Ontario). His father, Rev. John Rothwell, was a native of County Meath, Ireland, where the family (originally, no doubt, a Scottish one) still holds large estates, under a grant from William and Mary. John Rothwell was graduated at Trinity College, Dublin, and became a clergyman of the Established Church. He married Elizabeth Garnett, of Athearn Castle, Ireland, and subsequently came to Canada. It is said that he was a man of liberal views combined with sterling piety, an enthusiastic sportsman and yachtsman, and a pastor who refused for many years to accept any remuneration from his parishioners. After preliminary education, the subject of this sketch entered Trinity College, Toronto, with the intention of studying law; but a year later he resolved to become a civil engineer, and entered the Rensselaer Polytechnic Institute at Troy, N. Y., where he was graduated, with high standing, as civil engineer, in 1858. He then went to Paris, and entered the Imperial School of Mines, where, by reason of the proficiency he had already acquired in civil engineering, he was able to finish in two years and a half the full three-year course, and to take the degree of Engineer of Mines. In 1861 he took the "practical courses" in mining and ore-dressing at the Mining Academy of Freiberg, Saxony. After traveling in Italy, etc., he went in 1862 to London, where, for the purpose of familiarizing himself with business methods, he entered the offices of W. T. Henley, a manufacturer of wire

Jan 1, 1902

By N. W. Johnson

Mount Isa Mines Limited (Isamine) has process control computers in the major surface plants -- lead smelter, copper smelter, lead/zinc concentrator, and copper concentrator. HP computers are used to implement the more complex stabilizing control loops and control schemes aimed at optimizing plant performance. The choice of control strategies is discussed with particular reference to long-term performance in metallurgical plants. These control schemes must be understood by the process metallurgists who are responsible for the performance and initial fault finding. Major emphasis has been placed on the ability of the control systems to handle most of the common plant upset conditions as well as providing improved performance under normal operating conditions. To illustrate the approaches adopted, the lead/zinc concentrator crushing system and the process bag- house control system for lead smelter off-gas handling are reviewed in detail. The improvements in both of these areas resulting from control systems implementation are discussed.

Jan 1, 1984

Discussion * of the paper of H. M. Chance, presented at the butte meeting, august, 1913, and printed in bulletin No. 79, July, 1913, pp. 1315 to 1341. George H. Ashley,+ Washington, d. C.:-Mr. Chance's long practical experience in reporting on coal lands admirably fits him for a discussion of the value of such lands. On behalf of the government geologists, I wish to express my appreciation of Mr. Chance's friendly, constructive criticism of the government method of valuing coal land in the first part of his paper and, at the same time, to reply to some queries he makes. All admit that coal has no " intrinsic "-monetary value, in the sense that a pound of coal of certain chemical and physical characters is worth " intrinsically " so many cents or fractions of a cent. The term has, however, been found very useful as including those natural factors of coal value, among which are its position and location in the earth, that affect its sale price in contrast with the other cost elements involved in the labor and capital necessary in mining, preparing, transporting, and selling the coal (extrinsic factors). Mr. Chance, while recognizing the " dual origin of value," does not offer any better terms. The survey agrees with Mr. Chance in his definition of coal conservation, that it means the fuller utilization of the heat contents of the coal, and the more complete recovery of the coal from the ground. Coal land withdrawals have not been made to keep such lands off the market, but to prevent their acquisition as non-coal lands before they could be classified so as to be disposed of under the proper law. Nor has the pricing of the more valuable coal lands above the minimum been to raise money for the reclamation fund, to which the money goes, but primarily to discourage the alienation, for holding or speculation, of coal lands not intended or needed for development, and, secondarily, to secure to the people the ?unearned increment," which they are certain in any case to be charged.

Jan 11, 1913

By A. Bentzen, S. S. Wong, W. K. Fletcher, B. J. Price, A. J. Sinclair

One hundred eleven pyrite samples from three porphyry-type deposits in the Canadian Cordillera were analyzed (many in duplicate) by AA spectrophotometry for Co, Ni, Cu, Pb, Zn and Mn. All elements have density distributions that are lognormal or combinations of lognormal populations. Co and Ni in pyrites show zonal patterns that relate generally to mineralogical zones in the porphyry systems, particularly if contoured as the Co/Ni ratio. High Cu and Mn values in pyrites also correlate with Cu-rich mineralogical zones. Other elements studied appear less regular in their distribution patterns, although Pb and Zn highs in pyrite seem to occur sporadically near the margins of porphyry systems. These data considered with two other studies permit construction of an empirical model for the distribution of certain minor elements of pyrites from porphyry systems of the calc-alkalic suite. In particular cases pyrite geochemistry shows potential as an exploration tool to aid in target definition for detailed exploration.

Jan 1, 1978

By Charles B. Dudley

THEO. N. ELY, Esq., Superintendent of Motive Power. DEAR SIR: It is now nearly three years since my first report to you on the subject of steel rails was written. That report, as you will remember, dealt principally with the question of the relation between the chemical composition and physical properties of steel rails and their power to resist crushing and fracture in actual service. Other matters were referred to or touched upon in that report, but the main question was, Why do some rails crush or break in service while others do not? You will doubtless remember that the principal conclusion arrived at was, that the softer rails are less liable to crush or break in service than the hard ones. Or, in other words, so far as conclusions could be drawn from the chemical analysis and physical test of 25 samples of steel rails which had actually been in service, these conclusions were that those rails which have the smaller amounts of carbon, phosphorus, silicon, and manganese are less liable to crush or break in service than those which have larger amounts of these elements. Or, again, looked at in the light * At the Lake George meeting of the Institute in October, 1878, I had the honor of presenting to the Institute, through the kind permission of the officers of. the Pennsylvania Railroad Company, the results of a study of twenty-five samples of steel rails, which had all been in actual service. Considerable discussion followed the publication of that paper, and there seemed to be a strong disinclination, especially on the part of the steel-rail manufacturers, to accept the conclusions presented. One of the principal objections urged against the conclusions drawn was, that they were based on too few samples; in other words, that no conclusions safe to act upon could be drawn from the examination of twenty-five rails. In view of this criticism it was decided to repeat the investigation with a larger number of samples, and with the aid of the experience gained in the first investigation. The results of this second study of steel rails are, by the permission of the officers of 'the Pennsylvania. Railroad Company, herewith presented to the Institute, with the sincere desire that they may aid in adding to our knowledge of this most important product. Like the previous paper, this is in the form of a report to one of the officers of the company, which will account for the style, and the manner of presenting the data

Jan 1, 1881

By W. H. Bassett

THE modern smelting and refining of copper is distinctly an American development. The present demand for sound and perfect castings for rolling is due to the development of American industry. Prac-tically every article made from sheet metal or, for that matter, from any form of metal is made by mass produc-tion methods. Faulty material disturbs the orderly sequence of operations and in addition requires expen-sive inspection and unbearable rejection of finished product. This demand, therefore, is positive and will have to be met. Some mines produce ore that can be smelted and re-fined without the electrolytic process into satisfactory copper for the wrought metal industry, and some of these ores carry small amounts of impurities that are of use in hardening and toughening the copper. Most of the copper ore mined contains impurities that must be removed and, fortunately, precious metals which are separated at the same time make this re-moval profitable. The modern electrolytic refineries have their methods so well under control that the product meets all re-quirements without question if properly fire refined and cast. The "if" in this case is important, because there is evidence of carelessness or want of control at times in the material from some of the producers. It is nec-essary that the melted cathodes should be saturated with oxide to dispose of sulfur and that the copper should then be poled to the proper pitch or set. Sometimes statements leak out to the effect that it is unnecessary to oxidize completely the molten cathodes and a little less rabbling saves poles, which are expensive. The re-sult is that the rolling mill gets porous castings and produces seamy or slivered sheets or strips. The condition of the molds, their temperature, and the temperature of the metal are all important to good copper cakes, wedges, or wire bars. Cracked, and burned molds leave rough places and porous spots. Molds which are out of shape, or cracked, make shrink-age cracks which gap open when the castings are hot-rolled. Dampness means porosity. Drops of oil mean porous or honey-combed areas. Poor or irregular dress-ing means mold wash in the castings. Cold copper or slow pouring means cold sets.

Jan 4, 1928

By S. M. Purdy

Under certain conditions of hot rolling and air cooling from the hot-rolling temperature, bars of a high carbon (0.40 pct C) chrome-nickel austen-itic alloy were found to show magnetism even though no ferrite or martensite could be detected by microscopic or X-yay methods. The appearance of magnetism in such alloys may come from chromium impoverishment of the austenite grains near the precipitated carbide particles. SPORADICALLY, hot-rolled bars of Silchrome 10, an exhaust valve steel, have been found to be magnetic. Because of the analysis of the alloy—0.40 pct C, 18 pct Cr, 8 pct Ni, 3 pct Si —magnetism is unexpected. Preliminary investigation showed neither martensite nor ferrite to be present; only austenite and Cr23C6. Since a literature search was fruitless, a brief study was made of the appearance of magnetism in this alloy. The only basic difference between the two heats is the nitrogen content. Permeability was measured using a Severn magnetic gauge. This instrument consists of a magnet mounted on a counterbalanced arm. A set of calibrated plugs is placed in contact with one pole of the magnet. The specimen is placed close to the other pole of the magnet. If the specimen pulls the magnet away from the plug, it has a permeability greater than that marked on the plug. This technique is swift and reproducible. Previous experience has shown that the permeabilities obtained corresponded to those obtained on a permeater with a field strength of 100 oe. Specimens from both heats were annealed at temperatures between 1700 and 2300°F. One set of specimens was water cooled and another furnace cooled. All the water-quenched specimens were non-magnetic; the furnace cooled ones were magnetic as shown in Table I with no difference being observed between the two heats. Microstructural examination of the specimens showed the expected increase in carbon solubility with increasing temperature. Carbide solution was complete at 2200°F. The specimens heated to 1900°F or below showed some carbide precipitation from the hot-rolled structure. A furnace cooled specimen from a given temperature showed less carbide out of solution than the water-quenched specimen from the next temperature below; e.g., the specimen furnace cooled from 2100°F showed less carbide out of solution than the water-quenched specimen from 2000" F. These studies indicated that the appearance of magnetism was not related to the quantity of carbon in or out of solution and it was related to precipitation at temperatures below 1700" F. A set of samples annealed and water-quenched from 2100° F was aged for 4 hr at temperatures between 1000" and 1600°F; all were non-magnetic. A second set of samples, similarly annealed, was aged 1 to 24 hr at 1200°F with the results shown in Table II. None of the latter set of specimens showed magnetism until they had been aged about 8 hr. Magnetism was quite strong after aging 24 hr. X-ray diffraction studies on several of the magnetic specimens showed that the austenite had a lattice parameter of 3.58A and that the carbide was Cr23C6. Several of these samples were electrolytically digested in 10 pct HCl in ethanol, with a current density of 0.1 amp per sq cm. None of the particles in the residue were magnetic. Accidentally, one cell was run at 1 amp per sq cm; e.g., magnetic particles were found in this residue. After careful separation, the magnetic particles were mounted on a quartz fiber and their diffraction pattern determined using a 5.73-in. Debye-Sherrer camera with CrK radiation. These particles showed a fcc structure with a lattice parameter of 3.57A. Prolonged exposure, up to 16 hr, produced no other lines on the film. The following facts seemed to be established at this time: 1) Austenite was the magnetic phase. 2) Neither ferrite nor martensite could be detected. 3) Magnetization could be produced by aging at 1200°F. One explanation of these data is that the carbide precipitation impoverishes the region immediately around the carbide particle of carbon and chromium and increases the proportion of nickel. All of these serve to increase the Curie temperature of the region around the carbide particle. If the composition change is enough, the Curie temperature will rise above room temperature. If the volume of the affected region is great enough, the magnetism will become detectable. At low aging temperatures, composition changes are great enough but the overall volume of impoverishment is quite small

Jan 1, 1962

By R. F. Rolsten

The preparation of pure metals by the thermal decomposition of volatile halides was developed byde boer' and van Arkel.2 This has proved to be a useful technique for the refining of columbium,the mechanical and physical properties of which are seriously altered by such interstitial contaminants as oxygen, nitrogen, hydrogen, and carbon. The conventional deposition surface of a resis-tively heated metal filament was replaced, Fig. I, with an indirectly heated clear quartz surface. The impure columbium (feed) was contained in the annular space between the Vycor deposition bulb and the perforated molybdenum retaining cylinder. The head assembly was attached to the deposition bulb by fusing the Vycor at "A". This unit was then connected to a vacuum system composed of a three-turn glass coil to eliminate fracture due to vibration or expansion, a McLeod gage, a cold trap, a two-stage mercury diffusion pump, and a mechanical pump. The entire system was cold outgassed, and the 10 to 20 g of iodine in the auxiliary bulb (reservoir) was held in dry ice to prevent excessive loss of iodine. The columbium was hot outgassed at 800" to 825oC with the pressure maintained at l0-5 to 10-6 mm Hg for 48 hr and cooled under vacuum to 200° to 240oC. Iodine was sublimed from the reservoir and collected in the deposition bulb. The feed material temperature was adjusted to give the desired iodide vapor pressure and the finger temperature of 1000" C was independently attained and measured with a platinum-platinum 10 pct Rh thermocouple located in the center of the nichrome wire helical heating element, "F." The system was attended until temperature equilibrium was established, whence it operated without attention. This is a definite ad- vantage over the conventional "hot-wire" technique which required either constant attention or automatic control. In operation, the iodine vapor originally introduced into the vessel reacted with the crude metal to form a columbium iodide. This iodide vapor diffused to the hot deposition surface where it thermally decomposed, depositing columbium and releasing iodine. This liberated iodine then diffused back to the crude columbium where iodide was formed again. Thus, by repetition of this process, the iodine carried pure columbium from the crude material to the filament, where it deposited. The success of the "iodide" process in producing ductile metals depends on preventing the transfer of oxygen, nitrogen, hydrogen, and carbon from the feed material to the deposit. In many cases relatively minor quantities of these interstitial contaminants impair the ductility of metals. The material produced by the iodide process has such exceptional ductility that it is frequently and mistakenly assumed that iodide metal is always of very high purity. This assumption is not necessarily true since a number of metallic impurities can also be transferred. In the present investigation, the temperature of the feed material was adjusted to iodinate selectively and the deposition temperature adjusted to decompose the iodides selectively. By this technique, some metals present in the feed material were prevented from codepositing with the columbium. It is quite important to have the feed material symmetrically located around the deposition surface in order to obtain a uniform deposit at the maximum rate. For example, Runnalls and pidgeon3 observed that, when the base of a titanium filament was about 1 cm from the feed material, deposition was rapid on that section close to the feed, but that the rate decreased with distance from the feed so that a

Jan 1, 1960

By Edward Keller

THE ASSAY FOR COPPER. SOMEONE some time ago remarked that some chemists still insist on telling us how to determine copper by the electrolytic method. The. writer must confess that he believes that everything is not known definitely as yet as to how the exact amount of copper is determined in such material as purest commercial electrolytic copper. Some of us are not yet convinced that the pure copper atom is at all times deposited from an acid solution and that no oxygen or hydrogen will, under certain conditions, accompany it. Difficulties with impurer material are frequent, but erroneous results are not always apparent, since these do not speak so readily for themselves as those in the first case. By this is meant that if a chemist finds 100 per cent. of copper in electrolytic copper it is pretty certain that he perceives the result to be wrong, while if he finds 0.1 per cent. of copper too much in a very impure material he is far more likely to be unconscious of his error. These, in a wide experience, are frequent happenings and the writer has always looked with interest to publications on this subject. In turn, he :feels justified in giving to others a few of his own observations. Up to a few years ago there were two methods of electrolytic copper assay in technical use, which had in common, that the amount of copper deposited on the cathode did not exceed 2 g., and they differed in that, for the one a large sample 1 (20 to 80 g.) was taken from the general sample by a splitting device, dissolved, and from the solution a small portion (to contain 1 or 2, g. of copper) measured out for the electrolytic deposition; in the other Method the copper was determined, generally in 1-g. portions of the separated coarse and fine portions of the sample, all of which passed -a 16 or 20-mesh screen, being accomplished by a 40-mesh screen,

Jan 8, 1913

By Henry S. Munroe

THE plan of organizing a summer class of students of the School of Mines, for the practical study of mining and miner's work, received at the outset the following cordial indorsement : I have thought over the plan proposed by you of taking the students to the mines during the summer, and of having them actually take part, under the direction of skilled workmen, in all the various kinds of mining work; and of using them as a carps of engineers to make Inside and outside surveys, particularly with a view to the detailed study of the geology of the mine. I have no hesitation in saying, that if the students have been previously instructed in the theoretical part of their studies, by lectures and practice during the winter, the plan would be an admirable one. Of course experience will suggest modifications of detail. From the work you have done at our mines this spring, I feel sure that you would be perfectly competent to carry out your plan, and I shall gladly aid you in any way I can. "Yours, sincerely, T. B. Coxe." The plan of the proposed summer school thus indorsed by Mr. Coxe was adopted by the trustees of Columbia College, and an appropriation of one thousand dollars, or so much thereof as might be necessary, was voted for the experiment. A volunteer class of thirteen students was formed, and the first summer school was held at Drifton, in July and August of that. year (1877). The following extract, from an editorial notice in the Engineering and Mining Journal, of August 11, 1877, will give an idea of the 'organization of the school and the work required of the students. "The students, on reporting to Professor Munroe, were divided into squads of two or three men each, and on Monday, July 2d, were assigned to the Care of skilled miners, selected for the purpose by the mine boss, for instruction in gangway work. Half of the students worked in the morning and the other half in the afternoon, one squad at a time with each miner. The times of going and coming to and from work were so arranged that each student spent four to four and a half hours in the mine each day. While in the mine they assisted the miner to load his car, thereby learning readily to distinguish 'slate ' and

Jan 1, 1881

By E. R. Parker, T. H. Hazlett

An understanding of the mechanism of creep of metals requires an accurate knowledge of shape of the time-deformation curve. An expression is developed which accurately expresses the creep curve for a number of structurally stable metals and alloys. VAST strides have been made in the development of high temperature creep resistant alloys; however, no sound understanding of the physical mechanism of creep exists to date. Consequently, creep resistant alloys are still developed by "cut and try" methods formerly so successful but now yielding returns at a continuously diminishing rate. It is apparent to all workers in the field that if the mechanism of creep were understood, much fruitless labor could be avoided. The dirth of fundamental knowledge has not discouraged the theorists. Speculation has flourished and numerous theories of creep have been proposed. A critical review of these theories reveals that, even though there are some general areas of agreement between the majority of the workers, there are many basic questions yet to be resolved.' It is generally conceded that theoretical speculation is far in advance of experimental evidence. The shortage of reliable creep data greatly hinders more rapid progress in this field. It is essential that the effects of different stresses and temperatures on the creep characteristics of metals be quantitatively determined. Once this has been accomplished, it will then be possible to evaluate the effects of alloying additions and, it is hoped, to provide a firm basis of facts for theoretical treatment of the creep phenomenon. The work reported herein was undertaken to determine the effects of such variables as stress, temperature, alloying, and structure on the creep characteristics of some metals. Material and Equipment Nickel was selected as the base material for the current investigation and an experimental program was initiated to determine the effects of temperature and stress on the creep characteristics of this material. Since a large quantity of high purity nickel was required for the proposed program and such material was not commercially available, it was decided to refine, cast, and prepare the required metal in our own laboratory. The resulting nickel test bars had the following composition, given in percentage by weight: Fe, 0.030 (1); Si, 0.003 (2); Ca, 0.001 (1); Mg, 0.020 (2); and S, 0.002 (2); to make total impurities of 0.056. The nickel (balance by difference) is 99.944 pct. The details of the purification process are described elsewhere.' This

Jan 1, 1954

In March 1956 a conference on geochemical methods of prospecting for ore deposits was held in Moscow. This conference was the culmination of a ten-year period of extremely rapid increase in both research and routine application of geochemical prospecting methods in the USSR. This activity was divided among groups centered in extremely widely separated bases of operation, ranging from Moscow and Leningrad in the West, Yerevan in the Caucasus, and Alma-Ata in Central Asia to Chita near the Manchurian frontier in the Far-East. The All-Union Conference on Geochemical Methods of Prospecting for Ore Deposits, as the meeting was called, was the first opportunity for these scientists from many parts of the country to meet and exchange experiences. It also served to introduce members of the different research laboratories located in the city of Moscow itself, where adequate channels of technical communication had not yet been established. As a result of the Conference, it was resolved that a concerted effort should be made for the participants to publish the results of their work. Two books have appeared as a direct response to this resolution. I. I. Ginzburg prepared a synthesis of the field of geochemical prospecting for minerals based on the material presented at the Conference. This volume has been translated into English and is now available. In addition, the individual papers presented at the Conference were assembled into a symposium volume and published in 1957 under the editorship of V. I. Krasnikov. Unless otherwise noted, these two books have supplied the source material for the present appraisal of the status of geochemical prospecting in the USSR. It is thus about four to five years old. In the years following the conference, the literature has carried a substantial volume of technical papers, together with a few monographs pertaining to specialized aspects of geochemical prospecting.

Jan 6, 1960

By H. O. Hofman

The substance of this paper was prepared for the Seventh International Congress of Applied Chemistry, held in London, May, 1909, under the title, Some Developments in Blast-Roasting. In the absence of the author, a short abstract of the paper was read, and the abstract only will appear in the proceedings of the congress. The present paper has been partly rewritten and considerably enlarged by information gained since the original was prepared; also some illustrations have been added. Blast-roasting* is a generic term for the process of forcing air through finely-divided metallic sulphide with the object of roasting and agglomerating in a single operation. At first the process was confined to a galena-concentrate; lime, limestone, or gypsum was added, to serve both as a diluent to keep separate the particles of galena that they might be thoroughly oxidized, and as a flux that the partly-roasted ore niight be agglomerated by the formation of some slag. Later it was extended to treat other metallic sulphides. The leading processes were the Huntington-Heberlein and the Savelsberg of Europe, and the Carmichael-Bradford of Australia. In the United States and Canada, the Huntington-Heberlein process has found application in some instances with galena-concentrates, for which it was originally intended; but this class of ore is not often treated alone, hence the process has had to be modified to suit conditions. The Savelsberg process has been transplanted to this country in about its original form. The Carmichael-Bradford is not used at present. The changes called for in the Huntington-Heberlein process to adapt it to the class of lead-bearing ores usually smelted have been the

Jan 1, 1911