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By Steven Mitchell

BACKGROUND Homestake Mining Company began milling operations at the Bulldog Mountain Mine near Creede, Colorado in 1969. The Bulldog Mill, rated at 350 tpd, produces a bulk flotation condentrate assaying about 180 oz/T Ag and 20% Pb, from heads of about 16 oz/T Ag and 2% Pb. The circuit is straightforward with two-stage grinding to 1-5% plus 65 mesh, followed by rougher and cleaner flotation. Reagents used are Z-6, Z-11, Aerofloat 242 and Aero Promoter 404, with an Aerofroth 65-MIBC mixture for a frother. Additional information on the geology, mine and mill are available in references (1) and (2). A flow sheet for the mill and CIP plant together is attached as Figure 1. Final flotation tailings normally vary from 1.5 - 2.0 oz/T Ag. These tailings are cycloned to produce sand for underground backfill. After cycloning, the sands are repulped and given a final scavenger float. This sand scavenger recovers a small additional amount of silver which recycles back to the main flotation circuit. The tailings are recycloned and pumped to the mine or, if the mine cannot accept sand, to tailings. The majority of the silver in the flotation tailings exists in the fine fractions; cycloning upgrades the slimes and lowers the assay of the sand. The sand, after scavenging, typically assays 0.5 oz/T Ag, and the slimes assay about 3.0-3.5 oz/T Ag. From 1969 to 1976 all of the slime tailings and the sand tailings not used underground were impounded in a tailings pond located about

Jan 1, 1983

By McQuiston. F. W., E. C. Tveter

Sulfide mineral flotation has been applied to all naturally occurring sulfides and several synthetics. Of even more importance is the fact that economic separations are now being made between sulfides of essentially all the different metals. The variety of methods and minerals involved in such practice make it difficult to characterize them except in terms of general factors which influence the practices used. Ore grade and mineral composition are the major factors determining the processing method and the extent to which processing must be carried to achieve optimum economic return for a given ore. Since the choice of treatment is also affected by such factors as mine location, shipping charges, smelter schedules, each ore is a separate problem even though mineralization may be similar; The dissemination of minerals in the ore naturally determines the fineness of grind required for liberation. However, since grinding costs are a major part of most milling costs, emphasis has been placed on means of rejecting gangue minerals at the coarsest size possible. This has led to increased flotation of middling products or bulk concentrates for subsequent regrind and retreatment. Reagent development has also played an important part in present plant practice. Relatively few new frothers and collectors have found application during the past 25 years and many have disappeared. In general practice, re- agent combination choice is now fairly consistent with the type of collector being chosen on the basis of the mineral to be floated, the frother on the basis of pulp alkalinity, and the modifiers primarily on the basis of minerals to be rejected. REPRESENTATIVE FLOTATION PLANTS The milling operations described in this chapter have been selected primarily to illustrate these differences in ores and processing methods for the major types of ore minerals. The compositions of these minerals are shown in Table 1. These concentrators were chosen as representatives, both on the basis of geographic location and mineral content of the ore treated. At least one mill is included from each of the major producers, but the primary object was to show the practice employed for the various ore minerals and the different approaches to the middling problems encountered. The individual plants which have contributed data to this study are listed in Table 2, with a summary of their operating data, and are discussed in the order shown.

Jan 1, 1962

By A. S. Yue, A. E. Vidoz, F. W. Crossman

Tensile specimens were prepared from a single grain of an epitaxially grown Al-CuAl2 eutectic ingot. The eutectic lanzellae were oriented parallel and perpendicular to the tensile axis of the specimens. Since the composite was of the eutectic composition, the aluminum-rich matrix could dissolve up lo 5. 7 wt pct Cu in solid solution and, therefore, was amenable to strengthening by precipitation hardening. The tensile properties of the eutectic single crystals were determined at room temperature as functions of interlamel-lar spacing, platelet orientation, and thermornechanical trealment. The obserced variations in composite stress and modulus with respect to the level of&apos; composite strain are discussed in terms of premature fracture of CuAlz platelets, a distribution function for the strength of the lamellae, and unequal strains due to localized fracture of&apos; platelets. The discontinuous fiber composite model of Kelly and Tyson is modgied to account for a changing distribution of fiber lengths during composite loading. The tensile properties at elevated temperatures were determined for the direc-tionally solidified eutectic oriented with platelets parallel to the tensile axis. The observed properties are attributed to the onset of plasticity of the CuAL2 phase above 150°C. DURING the investigation of whisker- and fiber-reinforced metallic matrix composites in recent years, two major problem areas have developed: 1) The fabrication of the composite involves tedious handling techniques in order to obtain a unidirection-ally aligned and uniformly spaced set of whiskers in the metal matrix. 2) Due to weak interfacial bond strengths or because of the formation of additional embrittling phases at the metal-fiber interface during long-time exposure or fabrication at elevated temperatures, many composite systems have exhibited considerably lower strengths than those predicted by a law of mixtures analysis.&apos; These problems have been bypassed by the technique of growing whiskers and plates of high-strength materials in a ductile metal matrix by controlled unidirectional eutectic solidification.2 The tensile properties of directionally solidified A1-CuA12 eutectic are presented here. This alloy consists of a ductile aluminum matrix, containing up to 5.7 wt pct Cu in solid solution, which is amenable to precipitation hardening by heat treatment and a reinforcing high modulus CuAlz intermetallic phase. The two phases are present in the form of alternating platelets or lamellae. The microstructural stability of this unidirectionally solidified alloy at elevated temperatures has been studied extensively.3.4 and preliminary tensile and bend tests have been reported. 5-7In the present investigation the tensile properties of the A1-CuA1, eutectic have been studied as a function of several ther-momechanical variables: solidification rate. heat treatment. rolling at elevated temperatures. and lamellar orientation. It was felt that the uniformity of structure and excellent interfacial bonding would give tensile properties concomitant with the metal matrix composite theory of strengthening proposed by Kelly and coson. 8-9 The tensile properties that were obtained point to a wide distribution of strengths for the CuAlZ platelets, which leads to large deviations from the predicted mechanical behavior for this composite. EXPERIMENTAL PROCEDURE Epitaxial Growth of Eutectic Alloy. The A1-CuA1, eutectic alloy was prepared by an epitaxial growth process. Sections of a master alloy ingot (total impurity content <0.008 pct) were placed in an alundum boat, melted. and directionally solidified to obtain a multigrained plate 12 by 2 by 4 in. This plate was tapered at one end to mate with a seed crystal 1; in. long and 4 by $ in. square. Then the seed-plate combination was placed in an alundum boat which sat in a quartz tube passing through the center of a horizontal resistance wound tube furnace. A dried argon atmosphere was maintained. The temperature gradient in the furnace was such that the liquid-solid interface of the eutectic alloy was located near the end of the furnace and could be observed through the quartz tube. Single-crystal plates were formed by melting the material back to the midpoint of the seed crystal of the desired platelet orientation and then epitaxially growing the plate from the seed by withdrawing the alundum boat from the furnace at a constant rate. This technique was used to produce aluminum and CuA12 lamellae parallel and perpendicular to the transverse direction on the plate. Metallographic examination showed that both phases were continuous across the original liquid-solid interface. It was also possible to grow a plate from two seeds placed side by side: and, although the lamellae of one seed were oriented at 90 deg to those of the second seed, the interface between the two grains remained parallel to the growth direction along the entire ingot length. Maintenance of a straight intergranular boundary during the solidification process was possible as long as both seeds were oriented with their original growth direction parallel to the solidification direction of the plate. Eutectic plates were directionally solidified at rates of 0.2, 1.0. and 4.7 cm per hr and sectioned transversely to the solidification direction to determine the apparent inter lamellar spacing of the lamellae. Metallographic examination was also employed

Jan 1, 1970

By James Bowron

CONSIDERING the importance of the steel trade and the strategic position occupied in it by the Birmingham District, it may be surprising to many to realize that even the first pig iron smelted with coke was made in Alabama on Feb. 28, 1876, although merchant pig iron had been produced in Rockwood, Tenn., in 1867, a plant which is still in active operation. The heavy deposit of Clinton ore extending from Pennsylvania into Alabama, varying greatly in accessibility on account of geological changes such as erosion or anticlinal upthrow, varies equally as much in thickness and in quality. The brown ores extensively scattered through the South also vary materially in quality, some being relatively low in phosphorus and high in manganese, and vice versa. The red ore varies materially in phosphorus, but the iron produced from these ores was always considered to be too high in phosphorus for treatment by acid Bessemer or open hearth and did not contain sufficient for the basic Bessemer process. Under these conditions there remained only the basic open hearth as a possibility, and for many years it appeared impossible to use it, because, with coke smelted iron, the silicon was too high to permit its use in basic lined furnaces.

Jan 1, 1924

By Lloyd Pollish, Robert N. Breckenridge

SUCCESS in any underground mining operation is determined by accessibility of the orebody, which in turn is dependent upon maintenance of passageways to the mining zones and temporary support of the voids caused by extraction of ore. This is accomplished by one or a combination of the following methods: timbering, back-filling, pillaring, or, more recently, rock bolting. Timbering has usually been the principal means of maintaining these underground openings necessary for mining operations. Timber, however, does not prevent ground movement beyond the scope of localized sloughing, which is indicated by the gradual failing of the timber itself. Besides this, timbering has always been a costly process, and with the decline of available supplies of timber close to the mining areas, mining men have constantly sought other methods of controlling ground. Rock bolting is now replacing timbering at an ever increasing rate. Experience has proved that this form of ground support is just as applicable to blocky igneous rock as to stratified rock. Besides preventing sloughing of the walls and back of underground openings, Fig. 1, rock bolting has a stabilizing effect on the surrounding ground in much the same manner that steel reinforcing rods add to the strength of concrete structures. Further, rock bolting is flexible and may be applied to any shaped excavation, whereas timber sets are in a fixed pattern and the ground must often be changed to conform with this pattern. Rock-bolting installations were made in metal mines of the Northwest as early as 1939. An exhaust air crosscut was driven that year in one of the Butte mines of the Anaconda Copper Mining Co. The crosscut was rock-bolted and gunited at the time it was driven and is still being used to exhaust hot humid air from the 3400 level of the Belmont mine. It is interesting to note that no sloughing or caving has taken place in the 14 years it has been open. Even though these early installations of rock bolts were successful, few men recognized their potentiality until recent years, when the coal mines started their programs of mechanization and the great trend toward roof bolting began. In some areas of the Northwest stopes that previously required heavy timbering and close backfilling are now being mined by the more economical cut-and-fill and shrinkage methods. When used in conjunction with timbering, rock bolting increases the efficiency of the operation by decreasing hanging wall dilution and by making it possible to blast larger rounds. Most of the rock bolts installed to date in mines of the Northwest have been the 1-in. diam slot and wedge type, but there has been a recent trend to- ward using the 3/4-in. diam expansion shell bolt shown in Fig. 2. In addition to these commercially manufactured steel bolts, wooden bolts have been used with considerable success by the Day Mines of Wall&apos;ace, Idaho. Installation of the slot and wedge type requires three distinct operations, with tools for each operation: 1—drilling the hole to proper diameter and depth, 2—setting the bolt, and 3—tightening the nut. Holes are drilled and bolts set with pneumatic rock drills. A number of setting or driving tools have been used successfully, but most follow the same general pattern. Usually the driving tool is designed to accommodate a short length of drill steel on one end and the rock bolt on the other end. In this manner the hammering effect of the rock drill is transmitted through the steel and driving tool to the bolt. When machines not having stop rotation are used, slippage is allowed between the driving tool and bolt or between the drill steel and driving tool. The rock bolt nuts are tightened either with pneumatic impact wrenches or with hand wrenches. Impact wrenches are desirable because they are faster and assure adequate tightness. Expansion shell bolts have the following advantages over slot and wedge rock bolts: 1—No special equipment other than a wrench is needed for their installation. 2—Installation is faster. 3—They are removable. 4—Holes need not be drilled to a specific depth as the expansion shell will anchor anywhere along the length of the hole. These advantages are offset somewhat by the lesser strength of the bolt, since expansion shell bolts are generally made from 3/4-in. diam steel as compared to 1-in. diam steel for the slot and wedge type. One manufacturer, however, is now fabricating expansion shell rock bolts from steel of high tensile strength, which gives this ¾-in. bolt a much greater strength than that of the mild steel bolt. Table I illustrates tests made by the Anaconda Copper Mining Co. to determine the proper hole size to use with various types of bolts and to determine

Jan 1, 1955

By James E. Adler, Timothy C. Richmond

The Stillwater District is located in south central Montana approximately 75 miles southwest of Billings, the state&apos;s largest city. It lies along the northeast front of the Beartooth Mountains and is within the boundaries of the Custer and Galatin National Forests. The first white visitors in the district were the early trappers, who were soon followed by the prospectors. These early prospectors were drawn to the area by gold and silver discoveries at Cooke City in 1870 as well as by the large gossan formation in Verdigris Creek near the west bank of the Stillwater River and by several scattered smaller gossan exposures throughout the area. The first patented mining claims were recorded in September, 1886.

Jan 3, 1974

By D. B. Williams

The end of the war in Europe and the Pacific failed to curb the upward trend of production in Venezuela,- which easily surpassed that of any previous year. The total production for 1945 amounted- to 323,369, 430 bbl., which was 26 per cent over the total for 1944, the previous peak in the history of the oil industry of the country. This increase was caused mainly by the greater demand for petroleum in the last stages of the war; the fact that the danger from enemy submarines had been overcome, which allowed all oil companies to use increased shipping facilities, and the fact that more materials were available for drilling operations. However, the materials supplied were by no means adequate and considerable credit is reflected on the Venezuelan petroleum industry for the increased production obtained by utilizing all available equipment to its fullest extent.

Jan 1, 1946

By K. M. Rolls, R. M. Rose, H. B. Shukovsky

Studies of the phase structure, critical current density, and resistive critical magnetic field of a 45 pct Nb-55 pct Zr superconducting alloy after final-size heat treatments are reported in this paper. A combination of optical metallography, X-ray diffraction, and electrical-resistivity measurements were used to determine the phase structure. Superconductivity measurements, made with heat-treated wires, are correlated with microstructure. Although no quantitative relationship between microstructure and critical current density is found, it is shown that SINCE Kunzler1 as well as Berlincourt, Hake, and Leslie2 first described the high-field, high-current-density superconductivity of Nb-Zr alloys, it has be- the critical current density is highest when the microstructure is finely divided by fibering, coring, precipitation, or fine-scale phase dispersions. The resistive critical field is very sensitive to the compositions of the phases present. Since the alloy investigated here is near the maximum resistive critical field for the Nb-Zr system, any phase decomposition results in a lower H,. Elimination of the effects of cold work lowers H, also. A possible interpretation of the latter in terms of internal surface superconductivity is suggested. come apparent that the resistive critical field and the current-carrying capacity of such alloys are, in large measure, dependent on composition and processing. The resistive critical magnetic field (Hr) for low current densities has been found to increase progressively with zirconium content until a flat maximum is reached between 50 and 65 pet Zr.3 For any single composition, a characteristic maximum value of H, is attained by heavily cold-drawn wire.4 critical current density (J,) depends not only upon cold work but also, apparently, upon microstructure. Heat treatments of cold-worked wires generally

Jan 1, 1965

By C. G. Dunn

James, Jones, and Leak (JJL) conclude that growth-rate and orientation-distribution data obtained in a steep thermal gradient should be used with caution to account for isothermally produced recrystallization textures. I agree. However, it is not clear whether they conclude a) that the orientation dependence of rate of growth of secondaries in (commercial) silicon iron depends on both temperature and a temperature gradient or b) that, in applying rate data obtained in a steep thermal gradient, the isothermal annealing temperature must be close to the temperature for which the rate data apply. Also, it is not clear what tem-

Jan 1, 1967

By Dennis V. D’Andrea, Sidney M. Runke

This paper describes the Bureau of Mines-El Paso Mining and Milling Company cooperative research program at the Emerald Isle mine3 near Kingman, Ariz. This research program was directed toward developing in situ leaching methods for 200,000 tons of ore exposed in the pit bottom and also 1,500,000 tons of ore under 200 feet of overburden adjacent to the pit. A test area in the pit bottom containing 15,000 tons of ore was blasted and leached. The results of this leach test were encouraging, and the entire pit bottom was leached in-place for about 7 months. Two test blasts under 200 feet of overburden and extending to 290 feet were detonated in an area near the open pit. The results of these blasts were evaluated by core drilling and permeability measurements. An in situ leaching system was designed, but not implemented, to recover copper from the 1,500,000-ton area near the pit. The company decided to terminate operations at the Emerald Isle mine in November 1975.

Jan 1, 1976

By Valentin R. Garfais

The world&apos;s petroleum production in 1928 is estimated at 1,322,896,-000 bbl., an increase of about 62,000,000 bbl. over 1927, as compared with an increase of over 133,000,000 bbl. in the previous year. The daily average was close to 3,600,000 bbl., of which the fields on the American continent produced about 84 per cent. The most important development during the year has been the partial success of the attempts to temporarily control production without appealing to legislation and, as a consequence, the increasing realization that, in order to reach a permanent cure for this situation, some form of legislation is necessary to&apos; make possible the conservation of the oil supply and the stabilization of the industry. The importance of such a control over American production is not merely local but worldwide, as the American oil supply is now and for years to come will be the controlling factor of the industry. United States.—Production in the United States, which in 1927 increased about 15 per cent. over the previous year, remained practically stationary in 1928, the total being estimated at 902,000,000 bbl., or 68.2 per cent. of the world&apos;s output. This uniformity in production during the last two years was due primarily to the curtailment of output from wells already drilled, it being estimated that the available or shut-in production at the end of the year was close to 500,000 bbl. per day, or equivalent to the combined production of Venezuela and Russia, the countries ranking second and third. Venezuela.—With a production estimated at 106,000,000 bbl., Venezuela has trebled its output in the last three years. The increase in 1928 was 43,000,000 which placed this country as second in rank, a position which it should easily maintain for years to come. The output could have been considerably larger had not the oversupply in the United States made it advisable for Venezuelan operators to enter into tentative conservation agreements. Russia.—In Russia, production has doubled in the last five years, and reached a new peak in 1928 with an output estimated at 87,800,000 bbl., or an increase of 10,000,000 bbl. over the previous year. Difficul-

Jan 1, 1929

By J. H. Schulman, M. H. Buckenham

Although much interest has been taken in the use of mixed collectors in flotation, this investigation is probably the first in which oppositely charged collectors have been considered. The results obtained and the techniques used could well be applied in the behavior of other mixe the behavior of other mixed collector systems and could possibly explain the effective flotation results which have been reported when various collector combinations have been used. Collectors conventionally employed in flotation systems are soluble in water, but many of their homologs of longer hydrocarbon chain length are insoluble. The properties and behavior of these insoluble compounds may be conveniently studied when they are spread as monolayers at the air/water interface on the Langmuir-Adam trough. Although some extrapolation is involved in applying effects observed at this interface to the solid/liquid interface where the action of collectors is most important in flotation, the technique nevertheless is most useful for the study and interpretation of flotation phenomena. Of particular interest in this field are investigations on the insoluble monolayers of the fatty acids, alkyl sulfates and alkyl amines; the penetration of these insoluble monolayers by soluble surface active components and their interaction with metal ions from the underlying solution.&apos;-&apos; Unfortunately, the insoluble xanthates and related compounds do not exhibit stable monolayer properties due to rapid oxidation at the air/water interface and, therefore, cannot be studied directly in this way. These approaches have enabled Leja and Schulman8 to suggest mechanisms explaining dynamic attachment of mineral particles to air bubbles involving collector-frother interaction and the adsorption of collectors onto mineral surfaces. In this and other papers 9-12 considerable evidence is presented to support the concept of collector-frother and metal ion-monolayer interaction and to emphasize the value of monolayer techniques in elucidating the flotation system. Molecular interactions resulting from monolayer penetration are determined by the nature of and the association between both the polar and nonpolar groups of the two molecules concerned. Stable complexes are formed on penetration when interaction takes place between both the polar and nonpolar groups, and although the resultant complexes are not necessarily true chemical compounds, the properties of the molecularly associated complexes are very different from those of the individual components. Shortening of, or changes from, a straight hydrocarbon chain in one of the reacting molecules reduces considerably the stability of the associated complex as do changes in temperature, pH and substrate composition. The effect of hydrocarbon chain length becomes most important when observed effects are to be applied in flotation studies where soluble homo-logs and, therefore, much shorter hydrocarbon chain lengths are used. The present investigation is based on Langmuir trough work carried out by Bowcott,l3 who studied the penetration of insoluble amine monolayers by potassium lauryl xanthate. Bowcott observed that cetyl amine monolayers were readily penetrated by xanthate, but found that with time the high film pressures resulting from penetration and association fell off, indicating decomposition and ejection of xanthate from the film. This decomposition was pH dependent. Of particular interest in this work were studies on an equimolecular mixed monolayer of the fully N-substituted ammonium compound, for example, cetyl trimethyl ammonium iodide (CTAI) and potassium cetyl xanthate. Despite the fact that the CTAI is water soluble and the xanthate on its own is incapable of forming a monolayer, the mixed film was stable up to a surface pressure of 67 dynes per cm. In this condensed state the xanthate was stabilized against atmospheric oxidation, although iodine injected beneath the film caused an immediate collapse. The stabilizing of xanthate against oxidation by association with an alkyl trimethyl ammonium bromide (TAB) could be important in flotation, and a study of the performance and behavior of mixed collectors therefore was undertaken. A modified Hallimond tube operated under controlled conditions was used to evaluate flotation. Surface tension measurements were made to investigate the properties of the soluble

Jan 1, 1963

By A. W. Ambrose

The underground losses of oil exceed by hundreds of thousands of barrels all the oil that has been lost in storage, transportation, or refining. The quantity lost is, of course, indeterminate; but when it is considered that the contents of an entire oil field have been excluded from recovery by invading waters, some idea of the amount wasted may be gained. Similarly, enormous quantities of gas have been lost underground. Conservation of the oil, therefore, should start before it is brought to the surface rather than after it is placed in storage tanks. Water is one of the most important causes for underground losses and the operator should give as serious consideration to an underground flood of water as he would to a destructive surface flood. The best insurance, of course, is to have the wells drilled in such a manner that water has no access to the productive oil and gas horizons, and on abandonment the wells should be properly plugged. The encroachment of edge water and the occurrence of waterin;the base of an oil sand present a very serious problem to an oil company sooner or later these waters are bound to cause considerable damage, if they do not entirely destroy the possibilities of further production. Too often, however, a field has been considered to be in a hopeless condition, whereas wells in as bad a condition in other areas have been repaired and the life of the field appreciably lengthened. The corrections are very often suggested by technical study. Very successful results have been accomplished by detailed underground work in the California oil fields, in Cushing, Oklahoma, and in other areas. The purpose of this paper is to outline briefly1 general methods of analyzing oil-field water problems in a producing or in a producing and developing oil field, with a view to suggesting repair work on offending wells. Reference is continually made to producing oil wells; the same general method of procedure, however, should be adopted in a gas field.

Jan 1, 1921

By E. C. Harder

CERTAIN typical characteristics of bauxites, ores of aluminum permit their classification into a number of categories, each of which has special features that enable grouping within it deposits from widely scattered bauxite fields. There may be local variations in conditions that have introduced differences of lesser importance between similar deposits in different fields, resulting perhaps from the influence of factors other than those that have produced the distinguishing features of each of the different groups, but in general the similarity between the deposits in each group is sufficiently striking to make the grouping indicated of interest. Several factors and conditions enter into the decomposition process that results in the development of bauxites and laterites and affects their character. The principal conditions favoring optimum bauxitization are: (1) pres- ence of rocks with easily soluble minerals yielding residues rich in alumina; (2) effective rock porosity, enabling easy access and free circulation of water; (3) normal to abundant rainfall alternating with dry periods; (4) vegetation, including bacteria, advantageously distributed; (5) available sources of appropriate solution and precipitation agencies; (6) a tropical or at least a warm climate; (7) low to moderate topographic relief, allowing free movement of the water table but a minimum of erosion; and (8) long quiet periods in earth history. Assuming that all of these factors are operating to a greater or less degree, it seems that the one that affects most the physical character of the resulting bauxite or laterite deposits is the chemical and mineralogical composition of the rocks that by their decay yield the bauxite deposits. This factor is used in the classification followed in this paper. In the process of weathering of ordinary silicate and carbonate rocks of the earth&apos;s crust, whether of igneous or sedimentary origin, it is the minerals of the alkalies that yield most readily to attack. The alkaline earth compounds also offer no great resistance, particularly the carbonates. Thus, among the rock-forming elements, those producing the most insoluble compounds are aluminum, iron, and silicon, together with certain ones of less importance, such as titanium, manganese, and phosphorus. In normal weathering processes such as prevail in temperate regions, the common minerals of rock decay are

Jan 1, 1952

By Gary E. McIntosh

This paper will discuss a US Bureau of Mines project designed to assess and predict the impacts which surface coal mining will have on the regional shallow groundwater systems in the Powder River Basin. The primary objective will be met through the accomplishment of the following: (1) The design and establishment of a regional network for monitoring shallow groundwater systems in the basin; (2) monitoring the direction and rate of flow, water quality, and aquifer characteristics of the shallow groundwater systems; and (3) development of a regional groundwater simulation model, with appurtenant subroutines to determine local effects.

Jan 1, 1980

By R. G. Treuting

Germanium single crystals strained in tension at 600°C slip on the {Ill} plane and, macroscopically at least, in the <110> direction. Deformation is in homogeneous: various localized rotations are observed, as is a banding consistent with secondary slip banding. The structure after deformation is polygonized with a domain size of about 2x1O-3 cm. In relaxation tests, an incubation period prior to flow is observed, of duration inversely related to temperature and applied stress. Under continuous loading, there is a sharp first yield point. A critical resolved shear stress therefore must be cited with respect both to temperature and to rate of loading. At 600°C, when loading proceeds at 2900 psi per min, it is 1310 psi. The yield point phenomenon is suggestive of Cottrell&apos;s solute atom atmosphere theory and five points of qualitative agreement with this theory are found. PLASTICITY of germanium at elevated temperatures has been reported by Gallagher,&apos; who ascribed it to slip on {Ill) planes and described some associated effects. Preliminary experiments with single crystals of silicon and germanium loaded as simple beams confirmed {ill) as the slip plane of both materials.V his was demonstrated by the standard technique employing traces on two surfaces of known angle on a deformed crystal of known orientation.3 These experiments did not fix the slip direction, since more than one glide system operated. Uniaxial tensile straining is preferred for this purpose in order to restrict slip to one predominant system and to provide an unequivocal determination of the orientation change with respect to the stress axis. Experimental Method Specimens were diamond-sawed from germanium crystals containing about 5x10-5 wt pct Sb prepared by the zone-leveling process described by Pfann and Olsen;4 these specimens measured about 81/2 in. long, 0.20 in. wide, and were of various thicknesses from 0.035 to 0.060 in. Prior to testing, a specimen was coated over 1 in. or more of length at each end with Apiezon wax, chemically polished (in a solution of 15 ml HF, 25 ml HNO,, 15 ml CH3COOH, and 3 to 4 drops Br2), and dewaxed in warm xylene. A brief re-etching after scribing through a complete wax coating with vernier dividers provided gage marks at 0.200 in. intervals on the polished surface. A specimen with grips soft soldered to the ends was passed through the furnace tube and the grips pinned to the tensile machine in series with a stress gage. The Schopper testing machine is best described by reference to the illustration on p. 107 of Schmid and Boas5 and is operated with the pendulum arm locked, fixing the upper head. Load is applied through the screw-driven lower head, manually or by reduced speed motor. The furnace is 21/2 in. long surrounding a 4x7/16 in. ID quartz tube and was positioned about the specimen to permit free motion. The inert or reducing atmosphere required was sufficiently provided by a flow of helium introduced at the center of the furnace tube, with the tube ends loosely plugged with asbestos paper. Surface corrosion was slight. The stress gage employs a Be-Cu strip with SR-4 units incorporated in a simple bridge network with provision for balancing and calibrating. The bridge output on loading is fed through a Leeds and North-rup dc amplifier to a Speedomax 10 mv recorder, and calibration is obtained by dead loading. Experiments of two types have been conducted. Most have been in relaxation at constant elongation. One stress-strain curve has been taken with the machine continuously driven. Following extension of a specimen, Laue X-ray photographs were taken to obtain the orientation change between deformed and undeformed regions, recorded on a single film by translating the specimen in a plane normal to the beam between exposures. Sequences of such multiple exposures were made on some specimens to include the entire orientation range on one film. Slip Direction To obtain a maximum orientation change with a single slip system, crystals of very closely <110> axial orientation were used. The classic determination of slip direction rests on establishing that direc-

Jan 1, 1956

By William Johnson

IT is now recognized that several important types of reactions in metallic systems proceed by the formation of nuclei and the growth of these nuclei. The process, of freezing is a simple example of this, as Tammann pointed out years ago.1Tammann held that the rate of freezing is determined by a rate of nucleation, expressed as the number of nuclei formed per unit volume of unfrozen liquid per second, and a rate of growth of these nuclei, expressed as the linear rate of radial growth in units of length per second. For isothermal freezing the conception is simple; for ordinary freezing, extending over a range of temperature, it is not as simple, for the values of the two constants must change with change in temperature. There is ample evidence that the postulated mechanism is correct even though a quantitative derivation of the rate of isothermal or of ordinary freezing in terms of the two constants has been lacking. In recent years other reactions have been found to proceed in a similar fashion. It has been well established, particularly by Bain,2-8 that the formation of pearlite from the eutectoid decomposition of the solid solu-tion austenite proceeds in such a way, and Polanyi and Schmid, Tammann and Crone, Parnop and Sachs, and others&apos;-1 have shown that the process of recrystallization proceeds in a similar way. Isothermal reaction rates have been determined for eutectoid decom-position by a number of investigators. Bain&apos;s2-8 work on the formation of pearlite from austenite is especially valuable in this respect-the type of isothermal reaction curve obtained, as illustrated in Fig. 13, showed an initial slow rate, accelerating to an intermediate maximum rate which then decelerated to the completion of the reaction; similar curves have been obtained by Wever and his collaborators.&apos; Other eutectoid decompositions show similar behavior: for example, the decomposition of the beta eutectoid in the copper-aluminum system, studied by Smith

Jan 1, 1939

By Barnabas Bryan

During the boom period of 1928 and 1929, several oil companies took advantage of high security prices to sell stocks, thereby securing money for the company very cheaply. Few if any of those companies realized that the money received was not at all cheap in view of the fact that it was for investment in fixed assets at inflated prices. Suppose a company borrowed twenty millions of dollars to expand its marketing facilities during the boom. It diluted its capital and acquired fixed property which could not earn its interest requirements during the following deflation and therefore consumed income from other company activities. The company also had to stand the deflation in the capital value of all the property it bought. Since the mistaken expansion during the boom accelerated the decline in net income during deflation, the financial position of the company was harmed in proportion to the amount of that expansion. Thus the company was unable to get money to buy fixed assets in the depression when all property is cheap. The same condition holds for the company that sold common stock for the purpose of developing potential production in a newly discovered oil field. Regardless of what the ultimate value of the new field may be, potential production does not increase the net income of the company. The difficulty of meeting the enlarged dividend requirements due to the increased number of shares outstanding impairs the financial position of the company during deflation in some relation to the probability of decreased dividends. This company also is not in a position to expand during the depression when properties and companies can be bought for a fraction of their real value. Expansion of fixed assets during boom times has been the ruin of many otherwise good companies. Some of those which most extensively bought property during the post-war boom have not yet recovered. A number of cases could be cited in sugar, leather, fertilizer and wool. This does not seem to be governed by the quality of the property bought, for examination shows the assets to have been of individual high quality in many cases. When recovery is long deferred it is likely to be true, as in sugar or textiles, that the industry has a large "potential" capacity for overproduction.

Jan 1, 1931

By A. W. Gauger

WITHOUT QUESTION the Commonwealth of Pennsylvania contains the most remarkable coal deposits of the whole world. Within its borders ,are to be found excellent coals ranging in rank from the high volatile bituminous of the western part of &apos;the state through the low volatile or semi-bituminous of central Pennsylvania to that aristocrat of solid fuels, anthracite, found in the East. . . . But while other states and even the Federa1 Government have recognized the needs of the coal industry, Pennsylvania has not. Though bituminous coal represents one of the most important industries in the state, far more important in annual productive wealth than agriculture, for example, hundreds, of thousands of dollars have been spent on agricultural research whereas little or nothing has been spent on coal investigation.

Jan 1, 1932

The plans for the activities of the Petroleum Division for the coming year do not differ materially from those of the past several years. The fall meeting is scheduled for Oct. 12 and 13 and is to be held at Tulsa, Oklahoma. The Division, of course, will take part in the annual meeting of the Institute at New York. A fall meeting will also be held in California at approximately the same time as the meeting at Tulsa. A number of papers are to be presented at the two meetings simultaneously. The various committees are at work arranging the programs. The Division will continue to be active in its various fields of endeavor, such as stabilization, production reviews, and economics, but special stress is to be laid on the engineering and research fields. In the past the Division has served as a forum for open and frank discussion of problems confronting the engineers in the oil industry. It is hoped that it will continue to function in this capacity. Papers presenting original ideas and extending the boundaries of knowledge and understanding in the field of petroleum production will be welcomed. Members who have interesting information to contribute should not wait until called upon by one of the Committees, but should offer a paper at the earliest opportunity. The past year has seen a decided strengthening of the control over production, with prospects of even more rigid control in the future. It is essential that production programs under such control be carefully planned and it is highly desirable that petroleum engineers take an active part in the planning, to insure efficient production of oil and minimize the waste of this natural resource. At a time like this, when it is difficult to keep the production of oil within reasonable limits, it may seem unnecessary to improve the efficiency of production methods, but, as has been aptly said, the trouble is not that we have too great a reserve of oil but that we are producing tomorrow&apos;s oil today. Therefore it behooves those who are entrusted with the engineering and scientific phases of production to learn how to get the greatest yield economically possible from the present and future fields in order that we may enjoy the advantages of petroleum products for a long time to come.

Jan 1, 1934