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By E. P. Polushkin, Henry L. Shuldener

This paper describes the results of microscopic examination of a series of brass pipes removed from apartment and office buildings in New York City, adjacent localities on Long Island, and Philadelphia. They were selected as typical of approximately four hundred pipe specimens obtained over a period of five years during an investigation of corrosion in hot-water installations. A part of the investigation is reported in this paper and includes a brief history of the pipes, a description of their inside surface and microstructure, and a study of the effects of corrosion, with particular reference to the structural aspects of local and selective dezincification. Although the bibliography on the corrosion of brass pipes is quite extensive, it refers almost entirely to corrosion in sea water. The authors believe that their examination of this series of pipes, which had been subjected to the corrosive action of fresh water for various lengths of time, may throw some additional light on the problem of corrosion. Pipes Examined The pipes were made by different manufacturers and their sizes range from 3/4 in. to 4 in. nominal inside diameter, the majority being within I to 2 in. They can be divided into two groups according to chemical composition: (I) with a copper content of 60 to 62 per cent and (2) with a copper content of 65 to 68 per cent. The first group (pipes made of Muntz metal) comprises 22 pipes and the second (pipes made of high brass) comprises 18 pipes. The pipes had been in service in various locations in the hot-water systems of the buildings involved. Some were taken from horizontal lines in the basement, some from overhead distributors and some from vertical risers. The distance, in terms of feet of pipe, of the specimens from the hot-water generator was no less than 75 ft. and often IOO to 300 ft. In the majority of cases the water-heating equipment was provided with a regulator to limit the temperature of the hot water supply. The normal range of temperature in pipe systems of this kind is Ioo° to 160°F. Water Supples The average chemical composition of the water supplies carried by the pipes is shown in Table I. In evaluating the corrosiveness of a natural water, four factors are considered of prime importance: namely, hardness, alkalinity, pH and silica content. The waters listed in Table 1 are characterized by relatively low hardness, 10, alkalinity, low pH and low silica content. The waters of lower pH and higher CO2 content are more corrosive. A characteristic of all of these waters is that they do not deposit a protective mineral coating as do waters with high bicarbonate of lime content, which would be reflected

Jan 1, 1945

By Caner Zanbak

Deformational behavior of a rock mass can be modeled with a constitutive law based on theories of elasticity, and plastic and viscous deformation. For most rock types, such constitutive models may be used with confidence because there is no geochemical interaction between the rock-forming minerals and water. However, if volume changes in the rock due to geochemical phase transitions are predicted, then these volume changes must be converted into mechanical parameters and must be included into the constitutive laws. In this paper, geochemical phase transitions between anhydrite (CaS04) and gypsum (CaS04-2H20) will be brought to the attention of researchers in rock mechanics. Hydration of anhydrite to gypsum may yield volume increases up to 62.6 percent and dehydration of gypsum to anhydrite may cause volume decreases up to 38.5 percent. If one were to convert the volume increases in hydrating anhydrite into strains and calculates the required stresses to restrict the expansions, the magnitude of stresses will be found at GPa levels. Such stresses on swelling anhydrite layers cannot be provided by geologic media. Therefore, the host rocks will deform under these high stresses. On the other hand, under increasing stresses, geochemical transition of anhydrite to gypsum may stop after some hydration of anhydrite, and anhydrite and gypsum systems may become stable. Changes in temperature and solution compositions in the anhydritel gypsum system also control the stability of the geochemical system, and therefore, the extent of volume changes. A similar conceptual model can be drawn for volume decreases due to dehydration of gypsum to anhydrite. In this case, stress reduction on the gypsum layer may cause extensive fracturing and changes in the state of stress in the host rock mass.

Jan 1, 1984

By H. Conrad Meyer

The wizardry of nucleonics has added new and greater dimensions to the almost inseparable "twins"-zirconium and hafnium. So close is their relationship that neither element is found free of the other in any presently known mineral. Although zirconium in the form of its oxide was discovered in 1789 by Klaproth, the metal in an impure, nonductile form was not isolated until 1824 by Berzelius. About 100 years later -1925-van Arkel and deBoer developed and patented a technique for the deposition in vacuo of crystalline, coherent, highly ductile metal of extreme purity on an electrically heated filament through the dissociation of gaseous zirconium tetraiodide. Within the past five years both zirconium and hafnium have been dramatized by the press and in popular science magazines. This has led to the false assumption that practically all of the world consumption of zirconium ores is used in the production of the metals. Recent statistics on the subject show that not over 15 pct of the zirconium ore consumed in 1958 went to ferrosilicon zirconium and zirconium metal. The rest was consumed in refractories, foundry sand and facings and ceramics. The importance of zirconium as a component in compact, relatively lightweight nuclear energy units, such as those now used in the submarine Nautilus,6 is well established. A rival of zirconium metal as a casing for atomic fuels is a newly developed ceramic body. It is claimed to be cheaper than zirconium-to withstand higher temperatures-and to be more resistant to corrosion. Whether such ceramic casings have the required low thermal neutron absorption cross section, high strength and easy formability of zirconium is yet to be demonstrated. Hafnium, because of its low order of abundance and its close chemical relationship to zirconium, was not definitely recognized as a new element until around 1923, despite prior claims. A study of the X-ray spectra of zirconium led to its identification. The circumstances leading to the discovery of hafnium were much less fortuitous than those surrounding zirconium. The more precise tools of arc and X-ray spectrometry lent themselves admirably to the search for elements to fill certain gaps in the periodic table. [ ] Pure, ductile hafnium-a metal similar in appearance to stainless steel-has a specific gravity of 13.3 (zirconium 6.52) and a melting point of 2,200°C. In other respects it closely resembles zirconium except in one important respect which gives it a preeminent position in nuclear energy development, namely, a high thermal-neutron absorption cross section. This explains the necessity of hafnium-free zirconium in atomic piles. The ability of hafnium to capture thermal neutrons makes it an excellent "moderator" of "governor" when used as control rods in nuclear reactors (Table 1).

Jan 1, 1960

By John Treweek

FOR many years the Homestake Mining Co. has devoted serious attention to the elimination of accidents, and ground is steadily being gained in this direction. In accident prevention work it is line-plunging with perfect teamwork and not the spectacular forward pass that brings progress toward the goal. In both surface plants and under- ground workings we regard "good housekeeping" as a first requisite for safety as well as efficiency. Under this term are included all types of safety guards and protective devices as well as cleanliness and orderliness it working places. Perhaps the most important factor in safety work is to arouse and maintain employee interest. The general morale and contentment of employees is of particular importance.

Jan 1, 1938

By Sherwin F. Kelly

THE geophysical scene shifts and alters, the emphasis changes, and new possibilities loom, but the tendency is always towards widening the field and deepening the analytical penetration. Seismic methods have had their heyday, the torsion balance is being displaced by the gravimeter, electrical methods are showing deeper penetration, soil analysis is the newest tool, and gamma-ray logging appears on the horizon. One of the striking features of re- cent geophysical work in the oil fields has been the marked decrease in the number of seismic crews employed. Although the percentage of company crews is believed to have increased appreciably. the sum total has fallen sharply, as shown by the figures for the Gulf Coast area. About two years ago probably over 100 seismic parties were operating there, whereas now there are only about 35. This decrease may be partly due to the low prices of petroleum with a consequent reluctance to spend money to increase crude-oil re- serves but more probably to the fact that reflection and refraction shooting have been carried on so extensively that they have been applied to a large pro- portion of the areas in which they may reasonably be expected to succeed. Some of the earlier enthusiasm, particularly over reflection prospecting, may have erred on the side of over- optimism; some of the present curtailment may be due to over pessimism; but in the opinion of various observers seismic work at the present rate seems to be at it- optimum. It nevertheless remains pre-eminent as a technique for detailing structures in areas where good reflections can be obtained and is the only method that will give accurate depth to definite beds. Results may be poor in certain areas but many regions still remain wherein it can be applied, so that plenty of structural mapping remains to be done by the reflection seismic method.

Jan 1, 1940

By R. E. Allen

ONE of the most unusual oil field engineering accomplishments of the past two years is the development and rapid advance in the directed drilling of wells. Directed drilling as referred to herein is the controlled steering of the drill stem in the required direction to a given location in the oil sand. The deliberate drifting of holes is an act so far removed from what has been considered good drilling practice that all of the old questions of correlation, drillability and production difficulties are revived. Only a few years ago, during the boom days of Seminole and Santa Fe Springs, the crooked-hole problem, as it was then called, occupied a primary position among the topics of the day in the fields of California and the Mid-Continent. The net result of all the discussion and study at that time was the conclusion that oil wells should be drilled with as little deviation from

Jan 1, 1933

By H. Kosmider, P. Coheur

New processes of blowing with an oxygen-enriched air or gas mixtures of oxygen and steam allow the steelmaker to produce, in a basic converter, a rimmed steel low in nitrogen (0.0020 pct), phosphorous (0.020 pct), and sulphur (0.020 pct). The physical properties (ductility) of the new steels are excellent. Furthermore, from the point of view of economy, these new methods of blowing offer outstanding possibilities. THE natural occurrence of geological deposits of iron ore and local economic circumstances led European blast furnace men to work large quantities of lean iron ore with a phosphorus content as high as 0.5 pct. The iron obtained from these ores generally contains 1.5 to 2.1 pct phosphorus, 3.6 to 3.9 pct carbon, 0.3 to 0.6 pct silicon, 0.04 to 0.08 pct sulphur, and 0.3 to 1.2 pct manganese. To produce steel from this pig iron, the steelmaker has at his disposal several processes. One of the simplest and most economical is the pneumatic process developed by S. G. Thomas in 1879. This process of steelmaking, called the Thomas process, consists of blowing through the bottom of a basic bessemer converter and is used widely in Western Europe, as shown in Table I. Due to the development of tonnage oxygen plants, this process has become more important because the use of oxygen offers new possibilities of steel manufacture. Not only may the quality of the steel be improved, but liquid pig iron also may be used, the composition of which does not meet the heat requirements of the blow with atmospheric air. It is not intended to present here a detailed scientific discussion of the basic bessemer process but rather to discuss briefly its industrial possibilities in the case of rimmed steel and when blowing with atmospheric air, oxygen-enriched air, or gas mixtures of oxygen and steam. This paper is based on the current practice at Klockner-Hüttenwerk Haspe's steel division, and at six Belgian and Luxemburg steel works. The latter are members of the Liege section of the C.N.R.M. (National Institute for Metallurgical Research) and are: ARBED, John Cocker-ill, Esperance-Longdoz, HADIR, Miniere et Metal-lurgique de Rodange, and Ougree-Marihaye, most of which are working with tonnage oxygen plants.' In order to avoid any misunderstanding, it should be noted that most of the techniques to be men- tioned, or similar ones, are used currently at many steel plants in Western Europe. Background The basic converters used in Europe have a capacity of 17 to 65 tons of steel, and are similar in shape to the one in Fig. 1. The lining is brick or rammed dolomite and has a life of 250 to 500 blows. The bottom is rammed dolomite and has a life of 40 to 80 blows. As far as we know, the type of blast used does not appear to have any influence on the life of the lining. Bottom life, on the contrary, depends very much upon the composition of the blast. It is only when

Jan 1, 1955

By Norman D. Fitz Gerald

THE growth of domestic requirements for motor fuel has been phe-nomenal, rising year after year in a fashion almost unique among com-modities, resisting depressions and forging rapidly ahead in times of prosperity. Consumption advanced from 226 millions of barrels in 1925 to 522 millions of barrels in 1938; or 130 per cent. The economic influ-ences generating and sustaining this demand are of vital concern to the petroleum industry. The general factors affecting utilization of motor fuel are well known but it is the purpose of this paper to employ the recently developed technique of economic dynamics to describe them mathematically. Such problems in economic analysis are complicated by the freedom of all the variables to fluctuate, their mutual interdependence, changing incidence upon one another, and the nonquantitative character of some of them. Economic quantities and relationships, unlike those of the physical world, are continuously changing and this dynamic characteristic is both a distinguishing and confusing feature in economic research. The com-plexities of the problems require application of the analytical devices of mathematical statistics to uncover the probable relationships between factors. The procedure employed is to formulate a logical relationship linking the dependent to the independent variables, and then simul-taneously, rather than sequentially, determine their separate effects by multiple correlation. This transformation of common knowledge to quantitative terms makes it possible to measure the probable effects of changing conditions upon requirements, assisting in the sound interpreta-tion of economic policies. The utility of the results of such dynamic analysis is in sharp contrast to the sterility of the trends and other simple empiricisms of descriptive statistics. It is not intended in this study to throw light on the reasons why any motor fuel at all is consumed; but to discover relationships explaining why more was consumed at one time than at another. Specifically the prob-lem is confined to the measurement of the influences of statistically

Jan 1, 1940

By J. C. Sarace, S. M. Sze, C. R. Crowell

Thin films of tungsten 077 n-type germanium, silicon, and gallium arsenide were obtained by reacting tungsten hexafluoride with the semiconductor surface in an argom atmosplrere at temperatures between 325° and 400° C. Capacity-voltage, current-iloltage, and photoelectric measurements were used to investigate the characteristics of the tungsten -semiconductor diodes thus Produced. The junctions are shown to he very close to ideal Schottky barlp/ers with barrier heights measured with respect to the Fermi energy of 0.18, 0.65, and 0.78 1.1 jar W-Ge, W-Si, and W-GaAs, respectively. The electrical properties of the W-Si interface show no deterioration when heated to 1000°C in dry forming gas for 5 min. A theoretical value of the Richardson constant, A, appropriate to the semiconductor-hand structure has been used in evaluating the current-voltage characteristics. ThE W-Si surface-barrier diode was initially proposed for investigation because the eutectic temperature with silicon (1400°C) is much higher than that in the Si-Au system 1370°C).1 This would permit more flexibility in heat treatment and possibly provide greater reliability at elevated temperatures. The lower work function of tungsten (4.54 ev)2 compared with that of gold (4.78 ev)3 also suggested that a lower barrier height would be obtained with tungsten and hence a lower forward bias and lower minority carrier injection ratio for a given current density. The investigation was extended to include the characterization of W-Ge md W-GaAs surface-barrier diodes. The tungsten films have been produced by reacting WF6 with germanium, silicon, and GaAs surfaces in an argon atmosphere at temperatures from 300° to 500°C.4 This process is a very satisfactory alternative to the relatively difficult process of evaporating tungsten films in vacuo. To ensure an adequate electrical characterization of the tungsten-semiconductor interface, three types of barrier-height measurements have been performed. The mutually consistent results obtained lead to the conclusion that the tungsten-semiconductor junctions are indeed of the Schottky type. EXPERIMENTAL PROCEDURE The apparatus used for producing tungsten films is shown schematically in Fig. 1. It consists of an argon carrier gas line to which metered amounts of tungsten hexafluoride can be rapidly added. The mixture passes through a heated reaction tube containing the semiconductor slices and is exhausted to a hood. The argon is purified by passage through a 6-in. column of titanium turnings maintained at 800°C. The tungsten hexafluoride dispensing arrangement was designed by V. C. Garbarini and W. R. Bracht.4 A measured amount of liquid tungsten hexafluoride is injected into the argon stream and vaporizes. The mixture passes through a sodium fluoride absorption cell to remove traces of hydrogen fluoride, then into the nickel reaction tube. The tube is 12 in. long with an inside diameter of 1/2 in. The center section is heated by a furnace of the self-supporting wire-filament type. It was chosen for its rapid heatup and cooling. The wall thickness is 10 mils except for a 3-in. hot zone which is 30 mils thick to reduce thermal gradients along the length. The samples to be coated are placed on a sapphire plate and centered in this section. The tungsten is deposited with the following sequential steps: the loaded reaction tube is flushed with argon at a rate of 500 cu cm per min and heated to 370°C. Then 0.45 g of liquid tungsten hexafluoride is injected into the argon stream. The samples are held at this temperature for 2 min. The tube and samples are then cooled to room temperature and the samples removed. Tungsten films were grown on (111) faces of silicon and germanium polished with Linde A abrasive and lightly etched with HF-HNO3. The GaAs surfaces were (100) faces chemically polished with a H2SO4-H2O2 solution. The films have typical sheet resistances of 0.2, 8, and 15 52/0 when grown on germanium, silicon, and GaAs, respectively. After the tungsten deposition, ohmic contacts were alloyed on the back surfaces of the wafers. Ohmic contacts to the germanium and silicon were obtained by alloying Au-Sb at 370°C, ohmic con-

Jan 1, 1965

By T. T. Read

FOR the second time the Mineral Industry Education Division opened the sessions at the Annual Meeting by gathering at the Engineering Woman's Club, Sunday at 3 p. in., and, in spite of the informality of the hour, with a good attendance of representative men in the educational field. The chairman of the Division, Thomas T. Read, after briefly reviewing some of the more significant events of the past year, introduced H. P. Hammond, professor of civil engineering, Brooklyn Polytechnic Institute, a leading figure in the project of the Engineers' Council for Professional Development for accrediting engineering schools. Prof. Hammond made it clear that the project is not to rate engineering schools but to accredit them; not to arrange them in order of excellence, but to segregate them into two groups, those that are entitled to recognition as genuine engineering schools, and those that are not. About thirty schools in the whole country will presumably fall into the latter class; they are typified by an unnamed institution where the teacher of mathematics bears the title of Professor of Civil Engineering and the man who teaches chemistry that of Professor of Chemical Engineering, and having no engineering instruction except some elementary surveying, but still claiming in its catalogue to be an engineering college. While everyone would like to avoid the necessity of accrediting engineering colleges, it cannot be avoided, since the University of the State of New York, and several other agencies, are already doing it. If it cannot be avoided it is best that it should be done by a qualified agency set up by the national engineering societies, so that the results may command respect and general acceptance. It is for this reason, and this alone, that the accrediting committee of the E. C. P. D. has been set up. It is now ready to begin its task, and during-the coming year it will accredit the schools in two of the seven geographical districts into which the country has been divided, beginning with New England and the Mid-Atlantic States.

Jan 1, 1935

By William L. Russell

A new instrument for measuring bulk and grain vol-urnes is described, and compared in accuracy with two modifications of Nutting's method, All three methods are reasonably fast, and in all three the probable error in the determinations of bulk volume can be kept down to about 0.1 to 0.2 per cent. INTRODUCTION The new pycnometer described in this paper is designed to give speed without sacrificing accuracy. Some time ago Russell1 described a somewhat similar appa-ratus; however, the instrument described in the present paper is more accurate. Nutting' designed the pycnom-eter shown in Fig. 1 (A and B), and Pirson3 has shown points like those of Fig. 1-D. The procedure described in this paper for using Nutting's pycnometer has been modified from that used by Nutting. CHOICE OF LIQUIDS The best liquids for measuring grain volumes are hydrocarbons or chlorinated hydrocarbons which evaporate slowly. Trimethylbenzene or mesitylene, triethylben-zene, carbon tetrachloride, and tertalin have been used for this purpose. Any of these liquids or mercury may be used for measuring bulk volume. PREVENTING ERRORS DUE TO INVASION OF LIQUID Errors due to the invasion of the porous, permeable bulk samples by the liquid of measurement may be prevented or greatly reduced by using mercury, by applying an impervious coating, or by soaking the bulk samples in the liquid of measurement until bubbles cease issuing from them. Errors are produced only by the invasion of the samples which occurs between movement when the samples are weighed in air and the moment the weight of liquid displaced by the sample in the pycnometer is determined. No error is produced by varying degrees of filling of the pore space of the samples by the liquid of measurement. The excess liquid should be wiped from the samples immediately before the weight in air W1, is determined, and they should be placed in the pycnometers immediately. OPERATION OF NEW INSTRUMENT The new pycnometer is shown in Fig. 2. It consists of two glass parts which fit together at a ground glass joint. The spaces J and D are connected by fine glass tubes E, and the space J must be larger than the space D by at least the volume of the largest sample to be tested. The projections H afford a grip for twisting when the two parts tend to stick together. The position of the sample in mercury is shown by I, and in other liquids by M. F is a permanent mark on the glass, and G is a tem-Some marker. In order to determine the position at which G should be placed, invert the instrument so that A is at the bottom, and fill space D. Place the cub K

Jan 1, 1958

By D. W. Frommer, M. M. Fine

Mineral dressing research showed that iron concentrates of commercial quality could be produced from the Pea Ridge deposit near Sullivan, Mo. Magnetic separation and flotation, on a laboratory scale, yielded concentrates ranging from 60.0 to 71.4 pet Fe at recoveries of 89.9 to 97.6 pct. Early in 1957 St. Joseph Lead Co. announced discovery of three new centers of iron ore deposition in east central Missouri.' The discovery resulted from exploratory drilling in the vicinity of a magnetic anomaly or high. A deep hole, drilled into the Pre-Cambrian porphyry to determine the cause of anomaly, penetrated a magnetite-rich deposit.' The magnetic surveys that revealed the anomalies were begun by the Missouri Geological Survey in 1929 and were continued into the 1930's.3 At that time an area in Crawford County known as the Bourbon magnetic high was located. A second anomaly, similar in size and intensity, was discovered about six miles to the northeast in Franklin County in the vicinity of Sullivan. This area was not studied in detail until the early 1940's. To determine the cause of the anomalies, the USBM drilled four holes at the Bourbon site in 1943-1944.4 The most productive hole penetrated four mineralized zones having a total thickness of 127.5 ft. These zones contained magnetite in rhyo-lite porphyry at depths between 1600 and 2000 ft. Additional iron ore below 2000 ft was considered a possibility at the time. Some years later, the USGS, Missouri Geological Survey, St. Joseph Lead Co., and others cooperated in sponsoring an aeromagnetic survey of the Bourbon-Sullivan area which resulted in discovery of a third high, about eight miles distant at Pea Ridge. This deposit, with an estimated reserve of 50 to 100 million tons of iron ore, is considered the main find, although other orebodies in the same general area are of definite interest.' When this discovery was announced, St. Joseph Lead also revealed plans to exploit the deposit jointly with Bethlehem Steel Co. A new corporation, Meramec Mining Co., was established, and 1962 was set as the target date for completing physical plant.2 Annual production goals of 2 million tons of beneficiated and pelletized iron ore were proposed. Preparation of the site for shaft sinking was begun in June 1957. Orebody and Character of Samples: Drilling to date has established the Pea Ridge orebody as a crescent-shaped pipe about 300 ft wide. Some drillholes were bottomed at 2800 ft in very good iron ore.6 he orebody is predominantly magnetite, although hematite and a mixture of hematite and magnetite occur in the upper areas and peripheral walls. Drillhole cores representing ore from different areas and depths of mineralization were grouped into composites for testing. These composites consisted of: 1) medium grade mixed hematite and magnetite, 2) high grade mixed hematite and magnetite, and 3) high grade magnetite. The medium grade ore came from three holes with depths of i350 to 1900 ft. The high grade mixed hematite and magnetite cores came from the 1790 to 2812-ft interval of one hole. Partial chemical analyses of the three samples, given in Table 1, reveal that all are excessively high in phosphorus and sulfur, and sample 1 is

Jan 1, 1960

The Raymond Memorial Volume, which the Members of the In-stitute have been so anxiously awaiting since the beloved man's death, is nearly ready for publication. It will contain about 45,000 words and some illustrations and a frontispiece portrait. This book promises to fill every expectation of the contributors to the volume and the host of admirers of the genius who so long guided the destiny of the Institute. It will contain one of Doctor Raymond's best stories, entitled "James and Jim;" his famous article on "Job on Mining;" and one of his poems entitled "The Grand Canyon." A biography of Doctor Raymond has been written by his daughter, who is the wife of a member of the Institute. The memorial addresses delivered by Dr. Henry F. Drinker and T. A. Rickard at the annual meeting in New York in 1919 will be included. There will also be very interesting reminiscences by H. M. Howe, A. S. Dwight, C. W. Goodale, R. W. Hunt, Lyman Abbott, J. F. hemp, T. A. Rickard. The volume has been edited by T. A. Rickard, which promises all that can be wished for the volume from a literary standpoint. The edition will he limited so that it is very desirable that orders for this volume be sent in to the Institute as promptly as possible. The price will be $5.00.

Jan 12, 1919

By J. F. Myers, R. J. Tower

"There is nothing new under the sun." All over the world, mineral-dressing engineers are working at their problems, no two of which are alike. Each encounters equipment and process problems. Many devise simple ways and means of overcoming their difficulties. Many of these problems are quite common in the industry, yet, since no one human being seems capable of thinking of everything, these problems at some plants often are looked upon as necessary evils. The purpose of this symposium is to gather together, from competent engineers, devices and practices that have been useful to them. Most of the ideas contributed are not new, yet there is no plant operator, old timer or youngster, who will not find some idea herein that will give him a suggestion for improving his operation. Space does not permit a complete elaboration on all of the contributions offered. Each item is summarized, but this will be ample for those skilled in the art of mineral dressing. A list of contributors appears at the end of the paper, and the superior number at the end of each item identifies its source. General Equipment A signal light to show that a steel bin, containing relatively line, moist ore, is full, can be made by suspending a copper rod in the bin to a sufficient depth to ensure ample contact with the ore. One wire of a 32-volt circuit should be attached to the rod and one to the side of the bin. Sufficient current will flow to make the signal light burn. A 110-volt circuit could be used, but 32 volts ensures safety.10 Fig I shows a circular bin for crushed ore. It is a concrete structure footed on the ground, using no supporting columns. Tailing from the sink-float was used for aggregate. Cross conveyors for discharging ore are not required, nor is a tripper for filling. Segregation is minimized by drawing from different gates. An exhaust fan on top of the bin eliminates condensation due to temperature of the ore.21 A beam with an adjustable point of suspension near the center permits rigging rolls for removal in a very few minutes. This makes unnecessary the lacing of the cable through the hub bolts on one side, around the shaft on the other, and the trouble of balancing the load.8 The ratchet handle on a Symons crusher may be replaced by a drum with a cable wound on it. When the cable is pulled by a crane or hoist it causes the drum to revolve and thus screws or unscrews the bowl. This reduces handwork and materially shortens the time required for the job.' TO Spread ore feed from an apron feeder over a belt conveyor, place a heavy steel bar about midway between the top

Jan 1, 1949

By John T. Galey

In all, 210 wellst were completed in southwestern Pennsylvania during 1939, which is 59 more than were drilled during the preceding year. Of this number, 137 were gas wells, which is a considerable increase from the 81 completed during 1938. Only 25 oil wells were completed, as against 28 in the previous year, and 28 dry holes, 6 more than last year. Shallow Development—Gas The increase in the number of gas wells is largely the result of a search for additional gas in Armstrong and Indiana Counties. Although a considerable number of wells were drilled in the latter county, the majority of them produced less than 100 M cu. ft. initial open flow. In Armstrong County, a new pool was opened in Cowanshannock township, producing from the third Bradford sand. Several large wells were obtained there, one of which produced an initial of nearly 12 million cu. ft., with a reservoir pressure of 1100 Ib. However, the productive area has been fairly well outlined by further drilling and shows that the pool covers only about 800 acres. The sand is 20 to 30 ft. thick, and probably has 5 to 6 ft. of pay. Thus this reserve is not an important one. Several wells were found in Menallen township, Fayette County, where the Big Injun sand has been having a play for the past three years, but the activity there is much less than a year ago. Oil On the west side of the Bradford sand gas pool, Cowanshannock township, Armstrong County, a well was drilled which flowed 100 bbl. the first day from the Tiona sand. The probability is that this well is a freak, as the Tiona has been drilled within a fairly close distance on every

Jan 1, 1940

By John T. Galey

In all, 210 wellst were completed in southwestern Pennsylvania during 1939, which is 59 more than were drilled during the preceding year. Of this number, 137 were gas wells, which is a considerable increase from the 81 completed during 1938. Only 25 oil wells were completed, as against 28 in the previous year, and 28 dry holes, 6 more than last year. Shallow Development—Gas The increase in the number of gas wells is largely the result of a search for additional gas in Armstrong and Indiana Counties. Although a considerable number of wells were drilled in the latter county, the majority of them produced less than 100 M cu. ft. initial open flow. In Armstrong County, a new pool was opened in Cowanshannock township, producing from the third Bradford sand. Several large wells were obtained there, one of which produced an initial of nearly 12 million cu. ft., with a reservoir pressure of 1100 Ib. However, the productive area has been fairly well outlined by further drilling and shows that the pool covers only about 800 acres. The sand is 20 to 30 ft. thick, and probably has 5 to 6 ft. of pay. Thus this reserve is not an important one. Several wells were found in Menallen township, Fayette County, where the Big Injun sand has been having a play for the past three years, but the activity there is much less than a year ago. Oil On the west side of the Bradford sand gas pool, Cowanshannock township, Armstrong County, a well was drilled which flowed 100 bbl. the first day from the Tiona sand. The probability is that this well is a freak, as the Tiona has been drilled within a fairly close distance on every

Jan 1, 1940

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 Robert E. Green, T. Hinton

The velocities of the three possible modes of elastic-wave Propagation have been calculated for single-crystal aluminum at 1-deg intervals throughout the standard steveographic triangle. The results are presented as isospeed contours. The deviations between the direction of maximum energy propagation and specirzen axes are presented as arrows drawn within the standard triangle. The orientation factors associated with dislocation nzotion on the primary slip system only and also on all twelve slip systenzs have been calculated for all three elastic waves. The orientation factors associated with a longitudinal standing--7aue resonant specivnen hazle also been calculated. The relevance of these results to ultrasonic attenuation measurements is discussed. DUE to the widespread use of ultrasonics in the investigation of the properties of solids a number of authors15 have discussed in detail the theory of elastic-wave propagation in solids. In this paper the modes of wave propagation are evaluated according to the procedure suggested by reeen' for the case of single-crystal aluminum at 1-deg intervals throughout the standard stereographic triangle. The wave speeds are presented in the form of contour diagrams within the standard triangle. The deviations between the direction of maximum energy propagation and the normals to the wave fronts are presented as arrows drawn within the standard triangle. The orientation-de pendent factors (orientation factors) associated with dislocation damping as derived in the preceding paper6 have been calculated for the case of aluminum at 1-deg intervals throughout the standard triangle. The orientation factors for dislocation motion on the primary slip system only and on all twelve slip systems are presented in the form of contour diagrams, for both the traveling- and the standing-wave conditions. The relevance of these results to ultrasonic attenuation measurements is discussed. ELASTIC-WAVE PROPAGATION Three waves can be propagated in a linear elastic homogeneous anisotropic medium. The velocity of propagation v of each of these waves in a medium of density p can be obtained from the determination of the eigenvalues and eigenvectors of the matrix equa- The A's are a series of moduli which are functions of the elastic constants cij and the direction cosines 1, m, and n of the specimen axis. In the case of cubic single crystals where there are only three nonzero elastic constants cll, c12, and C, the A's are, The solution of Eq. [I] will give the wave speeds (eigenvalues) and the direction cosines a, 0, and y of the particle displacements (eigenvectors). To obtain the direction of maximum energy flux requires the calculation of the energy-flux vector ET with com- w is the angular frequency, A, the amplitude, and v the velocity of the wave. The direction cosines a, b, and c of the energy flux vector are then given by

Jan 1, 1967

By K. R. Weller

The Ardlethan Tin Ltd. concentrator typically recovers 55% of the tin in a gravity concentrate at 51% grade from fresh ore assaying 0.5% Sn. Coarse gravity concentration is performed in a complex circuit involving Reichert cones, spirals, shaking tables and two regrind mills. The paper describes how flow and size-by-size sample data from a steady-state survey were used to construct a computer model of the plant involving 46 process streams. The data reduction involved a computer- aided mass balancing technique, recovery-size modelling of gravity concentrators and the use of a mineral dressing flowsheet simulator. The model was used to simulate possible rearrangements of the available equipment. Early simulations indicated that improved performance could be obtained by using spirals to-treat cone middlings or tailings rather than cone concentrates. A test spiral rig was used at Ardlethan to determine typical performances for all cone product streams and the results were incorporated in new simulations. A revised circuit was recommended and implemented by Ardlethan Tin as far as physical restraints within the plant would allow. Production figures show that a substantial increase in tin recovery and 10-15% increase in milling rate were achieved following the circuit changes, and these improvements were sustained over a six month period.

Jan 1, 1984

By H. E. Stauss, G. Sandoz

THE purpose of this note is to draw attention to the possibility that a melt may be contaminated by a material not in direct contact with it by means of gaseous intermediate agents. In recent years silicon has assumed a position of importance because of its use in rectifiers and transistors and close attention has been required to control of both purification and contamination during all stages of preparation.' This note reports the observation that a graphite heater may have contaminated silicon ingots without direct physical contact through reactions that developed gaseous products. Several ingots made with the equipment of Hino and Stauss,2 using a graphite heater in a dried helium atmosphere, were found to have a small amount of a very hard substance on the free surface. X-ray analysis by F. W. von Batchelder showed the sub- stance to be Sic. Similar contamination was not found when the heater was tantalum, indicating that the carbon had not come from an original impurity in the silicon powder. One source of the carbon could have been volatile matter released from the graphite heater. This heater had been used about ten times at the time of the observations. A second source of carbon could have been a direct reaction between the quartz crucible and the graphite heater to form CO, or an indirect reaction involving a crucible-melt interaction and volatile SiO as an intermediate product. Such reactions should have developed Sic on the heater; and in fact a yellow powder did form on the inside of the graphite heater although its composition could not be determined. References 'H. C. Torrey and C. A. Whitmer: Crystal Rectifiers (1948) Chapter 10. New York. McGraw-Hill Book Co. 2 J. Hino and H. E. Stauss: Trans. AIME (1952) 194, p. 656; Journal of Metals (June 1952).

Jan 1, 1954