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By Merle L. Bowser, Lawrence W. Scott, John N. Murphy

The environmental status of underground mining operations is critical to the health and safety of the miners; particularly in a large mine, the multitude of interacting parameters that can favorably or adversely affect the environmental status makes the manpower requirement of the routine checking of specific areas and conditions a formidable one. While the concept of environmental monitoring for miners has been considered for some time, until recently the availability of sensors to reliably measure the parameters of interest severely limited the utility of such systems. The status of sensors for mine use and the evaluation of enviornmental monitoring systems is reviewed.

Jan 1, 1980

By P. G. Shewmon

A novel technique for determining the surface energy (?) and its derivative with respect to orientation, (?') is described. Essentially it involves the 'floating" of a wedge on the substrate, said wedge being made of a material which is not wet or only slightly wet by the substrate, i. e., as a greased needle "floats" on water. A thermodynamic analysis of a system in which the wedge is supported entirely by surface energy is given. If the original suyface is not at a cusp orientation, the surface tension is directly measurable from the groove angle formed. If the original surface is at a cusp orientation, there may or may not be a groove depending on the relative value of ?' and the weight of the wedge. Experiments primarily on copper and silver showed that sapphire, quartz and refractory metal wedges were wet while graphite wedges were not. The technique was demonstrated to work using graphite wedges, but the results obtained were not as eccurate as those obtained by other workers using the wire-creep experiments. It is concluded that the technique might prove most useful with non-metals where ?' is large and filament creep experiments would be quite difficult. If an absolute value of the surface free energy (?) of a metal is to be determined, the most reliable methods used to date measure an average over the various orientations exposed on a polycrystalline sample. For example, ? for silver, gold, and copper have been measured by determining the force required to just keep a thin wire,' or foil,' specimen from contracting under the influence of ?. Herring 3 has predicted and experiment confirms, that the sensitivity of this method is inversely proportional to the grain size.' Thus it cannot be used to measure ? for a particular orientation by using a foil single crystal or a very coarse-grained specimen. An accurate value if ? for tungsten averaged over a range of orientations has been determined using a field emission technique. The same techniques cannot or have not been used to measure ? for non-metallic solids, and as a result the values available are much less accurate.4 This Paper resents a means of making an absolute determination of ? for a particular surface orientation on any solid, as long as the given surface orientation does not break up into other orientations during an anneal. Experimentally ? is found to vary with orientation and at a few low index orientations it is found to have a cusped minimum, i.e., the derivative of ? with respect to the orientation of the surface changes discontinuously at the low index orientation, see Fig. 1. The slope of a plot of ? vs orientation (herein designated ?') is called the torque on the surface, since it tends to rotate the exposed surface toward the low index orientation, or if the surface is at the cusp orientation it opposes any force tending to rotate the surface out of the low index orientation. The ratio ?'/? has been determined for a few metals, but in cases where this ratio is high there is presently no means of determining either ?'/? or the absolute value of ?' for the orientations present on an annealed surface. The technique discussed herein also provides a means of determining an absolute value of ?' for those orientations which deviate only infinitesimally from a cusp orientation. It should work best on surfaces where ?'/? is large; that is, for cases where no other technique is available for measuring ?'. Aside from trying to learn more about surfaces through measuring ? and ?', the primary reason for wanting values of ? or ?' is to study adsorption. From measurements of the variation of ? for a particular orientation with the concentration of an impurity, one can obtain the number of impurity atoms adsorbed per unit area (Ti) on that orientation using the Gibbs adsorption equation.' where µi is the chemical potential of the adsorbed impurity. Thus, if absolute values of ? could be obtained for the free surface of a given surface orientation as a function of µi, ri could be determined for the given orientation. Furthermore, by equilibrating a grain boundary with the given surface at various values of ki, one could also determine ri for the grain boundary. Similarly Robertson 6 has pointed out that if y is taken to be a continuous function of and µi, then a2 ?/a @a µ2 = a2 ?/a pi a +. Thus, at all orientations away from cusps the following equation holds From a measurement of ?' vs ki, it is thus possible

Jan 1, 1963

By L. G. Marshall

WHILE surveying in a small Western mine, the following problem was encountered: Two traverses had to be connected by running a traverse line down the main hoisting shaft, which was the only connection between the two levels. The shaft was inclined at about 80 deg. from the horizontal and measured 8 by 10 ft. The distance between levels was about 110 ft., measured on one side of the shaft. The surveying equipment consisted of a transit, tripod, level rod, 100-ft. chain, and plumb bobs. There were no side or top the- scope attachments with which to take large, vertical angles. Therefore, we were confronted with the problem of taking readings between two points, one of which could not be seen through the instrument when set up under the other point, owing to the obstruction of the horizontal plate, and of measuring the distance between these points with a chain that was too short. The method of a line of plumb bobs down the shaft was impractical because a setup would be needed part way down the shaft, which would call a halt to all hoisting operations for some time. After considerable experimentation the following method was used.

Jan 1, 1936

By Howard L. Hartman, Burke O. Trafton

There is a fruitful area of computer competence which has gone virtually unnoticed by the mining industry. This is in the solution of its numerous fluid-flow distribution problems, involving the circulation of air, water and other fluids in conduits through mines. Typical of these is the mine ventilation system, which circulates air through mine openings to the working faces. The networks of interconnected airways in large mines-often resembling a tortuous maze or labyrinth defying representation by schematic, let alone solution-must somehow be resolved and analyzed, if effective and safe control of the ventilation is to be maintained. These are admirably suited to programming for solution by high-speed electronic computer. Not only can direction of flow be determined but quantity and head loss as well. EARLIER EFFORTS AT NETWORK SOLUTION The only prior attempt to solve mine ventilation networks by digital computer methods was made by a Japanese investigator1 in 1958 whose work went unpublished. Unfortunately, he employed a method of network analysis little used in the United States and one which could accommodate a maximum of only 30 airways. While his analysis seems unnecessarily cumbersome and involved, it did suggest that a digital computer approach was feasible.

Jan 9, 1963

By P. A. Beck, Hsun Hu

It has been known for many years that in cold drawn polycrystalline aluminum the recrystallization texture is practically identical with the deformation texture.l,2,3 V. Goeler and Sachs4 stated that in cold rolled polycrystalline aluminum, too, the deformation texture is retained upon recrystallization. This behavior was interpreted by Dehlinger9 as an indication that each recrystallized grain inherits the orientation of the matrix in which it grew. However, Burgers and Basart showed6 that in deformed aluminum single crystals the orientation of the recrystallized grains strongly deviates from that of the matrix. Barrett demonstrated8 that even in deformed polycrystalline aggregates the local orientation within each deformed grain changes on recrystallization. No explanation has as yet been offered of how the aggregate texture can be retained, while the local texture is everywhere changing. According to Burgers and Louwerse6 the orientation change on recrystallization in compressed and rolled aluminum single crystals corresponds to a rotation around [112] axes lying in the active slip planes and perpendicular to active slip directions. This orientation change was rationalized by them on the assumption that the orientation of the recrystallized grains is determined by the orientation of the available nuclei, and that these nuclei are small fragments of the deformed crystal, rotated in the deformation process. Barrett pointed out,? however, that these assumptions were by no means proven, and that the total volume of material necessary for the nuclei is so small, that it must be available in any orien- tation whatever. It is, therefore, unlikely that an "oriented nucleation" theory could satisfactorily explain the orientation changes in recrystallization of a deformed crystal. Furthermore, in contradiction to Burgers and LOU-werse's conclusions, Barrett's results for the orientation change could be best expressed in terms of rotations around. [Ill] axes. Thus agreement is lacking not only in the interpretations but apparently even in the experimental results contributed by the various investigators. The orientation relationships on coarsening* in a highly oriented polycrystalline matrix were first investigated by Burgers and Basart.5 They produced a fine grained highly oriented matrix by the recrystallization of a compressed or rolled single crystal of aluminum, and studied the orientation relationships in three successive generations of crystals: the "deformation texture" in the single crystal, the recrystallization texture, and the coarsening texture. Burgers24 showed that the preferred orientation of each successive generation was almost always widely different from that of the preceding one, but that the coarse grains often approximately reverted to the orientation of their grandparent, the deformed single crystal. This observation, and the idea that the orientation of the coarse grains is determined by that of the available "nuclei," led to the concept that the coarse grains are nucleated by the remnants of the deformation texture.12,15 On the other hand, Bowles and Boas16 found, in a carefully conducted experiment, that in recrystallized fine grained copper of cube texture coarse grains grow in orientations which can be derived from the orientation of the recrystallized matrix by rotation around a [lll].] direction: the coarsening texture here does not appear to be related in any simple manner to the original rolling texture from which the cube texture had been obtained by recrystallization. It may be assumed that in a recrystallized material, even with a strong texture, there always are present some grains of practically any orientation. These may serve as "nuclei" for the coarse grains, provided that the conditions are favorable for their growth. The existence of a coarsening texture may be considered as an indication that grains with certain relative orientations with respect to the preferred orientation of their neighbors can grow much faster than others. This "oriented growth" theory was briefly suggested by van Arkel, as early as 1936,13 and it was mentioned by Burgers." Recently, C. G. Dunn produced direct

Jan 1, 1950

By J. V. Emmons

THE processes of hardening and tempering steel tools within the past 15 or 20 years have been so developed that the forward strides of the industry can scarcely be followed by the average observer. No small part of the credit for this phenomenal advancement is due to the improved methods of measuring the high temperatures necessary. Pyrometry has made possible the discovery and use of the many special alloy steels the wonderful properties of which are revolutionizing the industrial world. So sensitive are these steels to changes of temperature that often a variation of only 10° F. at a critical point of the heat treatment will cause the failure of the tool. In the tool-manufacturing industry today, accurate control of the many heating operations is imperative. The principal processes in the manufacture of tools that require accurate high-temperature measurements are annealing, carburizing, hardening, tempering, and laboratory research. Several other operations, such as forging and straightening, use rougher and correspondingly less accurate methods. These operations are usually performed in the following approximate ranges of temperature: DEGREES F. DEGREES F. Annealing 1000 to 1700 Tempering 200 to 1200 Carburizing 1400 to 1000 Forging 1400 to 1800 Hardening 1400 to 2500 Straightening 300 to 1300 Laboratory research covers the entire range. Annealing and carburizing are usually done in muffle or semi-muffle furnaces, heated with coal, coke, oil, gas, or electricity. Many of them are of large size, holding several tons of steel at one charge. Both indicating and recording pyrometers are used. The recording instruments are generally of the thermoelectric type, while for the indicating, both optical and thermoelectric are used.

Jan 9, 1919

By Oscar A. Glaeser

THE mine and plant of the United Verde Copper Co., located in Yav-api County, at Jerome, Arizona, have been described in various technical publications and, therefore, a brief outline of its essential features will suffice. The orebodies are of the schist replacement type, the main sulfide mass being a large lens-shaped body approximately 7 acres in cross-sectional area. In general, the mineralization is found along the iron-schist contact, with the orebodies extending about 1000 ft. along this contact and varying from a few feet to 250 ft. in width. The mine is located on a mountain slope and has openings into it on three horizons, as follows: 1. Raises and ore passes open vertically into the shovel pit. These extend down to the 1000-ft. level, where they terminate as loading bins in the Hopewell adit. The main fan intake air shaft, which also extends vertically down to the 1000-ft. level, has its surface opening on the hillside at the extreme north end of the shovel pit, and the main mine air return exhausts through a raise at the extreme south end of the shovel pit. 2. The 500-ft. level adit. 3. The Hopewell adit on the 1000-ft. level. The mine has a vertical downward extent of 2000 ft. below the 1000-ft. level. Underground operations are carried on through two main shafts, both of which are wholly underground. Shaft 5 is the ore-hoisting shaft. It has three compartments and extends from the 800 to the 3150-ft. level. Shaft 6 is the service shaft, and is used for lowering and hoisting men and material. It has a large cage compartment and three smaller compartments for counterweights, ladderway, and pipe and power lines. This shaft extends from the 500 to the 2550-ft. level, and is now being extended to the 3000-ft. level. An air shaft for the downward movement of fresh air from the fan has been provided, and extends to the 2550-ft. level at this time. Work has been started to extend this air shaft to the 3000-ft. level. A return airway for vitiated mine air, in the form of raises and short connecting drifts, extends downward to the 2100-ft. level. The underground mining operations extend from the 300 to the 3000-ft. level. There are about 45 stopes in active operation on the 17 levels

Jan 1, 1929

By J. E. Forciea, O. E. Palasvirta, L. G. Hendrickson

AH pilot and commercial plants working with Mesabi Range taconite employ wet magnetic separation. Progress is being made with a dry magnetic process, but this has not yet been applied to taconite except in the laboratory and pilot plants. Flowsheets in all five plants are similar, including multiple stages of grinding, each followed by magnetic separation, which rejects a finished tailing. The flowsheet in Fig. 1 is used in the preliminary and commercial plants of the Erie and Reserve mining companies and in Unit C of Oliver's Pilotac plant. At Erie the desliming operation is omitted. In the Reserve plants two ball mills are used with each rod mill. Pilotac uses flowsheet 2 in Unit A-B and has also tested flowsheet 3. Principal differences in the three flowsheets are the number of grinding stages and the type of roughing. The terms open-circuit roughing and closed-circuit roughing are best defined by the diagrams. Special Test Data Given in Table I: For the Erie and Reserve commercial plants, Table I reflects routine conditions. Pilotac, the experimental plant, has been run with several flowsheets, including those followed at Erie and Reserve's commercial operations. Pilotac data for these last two flowsheets are similar to commercial plant results and are not repeated in Table I; statistics are given, however, for special test conditions. using other flowsheets. when the objective was to 'to extra-grade concentrate, Variations Among Taconites: Although crude ore tributary to these plants is generally classified as taconite, there are important differences in mineralogy and fineness of dissemination.

Jan 1, 1959

By A. R. Krause, C. Laird

In order to establish whether or not there is a real temperature effect in fatigue (independent of environment) , poly crystalline copper and Cu- 7.9 A1 alloy have been cycled at 298° and 7° K in vacuo and the fatigue lives compared with those in air and in liquid nitrogen. The lives of both copper and the alloy were found to be highly temperature-dependent in the absence of environment. This result casts serious doubt on the validity of the cell structure hypothesis for stage I crack propagation as presently formulated, because it predicts that there should be no such tempevnture dependence. On the other hand, the plastic blunling process is consistent with the result. Effects of environment aside, the homogenization of slip which accompanies testing at low temperature, and at low strains, seems to be the main cause for increased fatigue life. At high strain amplitudes, the fatigue lives of wavy slip materials, typically copper, are independent of temperature.' It is well-known, however, that low-strain lives greatly as as the temperature of testing is decreased. By contrast, the lives of planar slip materials, such as Cu-7.9 pct A1 alloy, increase to an even greater extent with decreasing temperature throughout both the high and low strain ranges.1'2'5 The mechanism of this temperature effect is associated with the earliest stages of fatigue failure,'" crack nucleation, and stage I growth,"' which is slow propagation along slip bands to the depth of a few grain diameters. Such life behavior has been interpreted on at least two different bases. On the one hand, those interested in the temperature effect at high strain amplitudes1 believe that stage I growth occurs by the plastic blunting process of crack propagation.7'9 They explain the effect in planar slip materials by the homogenization of slip* which accompanies fatigue testing at low temper- atures and serves both to delay crack nucleation and to decrease the rate of stage I propagation. On the other hand, Holt and Backofen,2 who have studied the effect in low strain fatigue, believe that stage I growth can be interpreted by a cell structure hypothesis.10-12 They have challenged2 the conclusion that there is a real temperature effect in this regime of fatigue testing and have interpreted the increased fatigue lives almost entirely in terms of the "environmental-protective'' effect of the liquid nitrogen and helium baths used to obtain low temperatures. This interpretation by Holt and Backofen2 may offer a means of discriminating between these two mechanisms as currently formulated and used to explain stage I growth. On the basis of the plastic blunting process applied to stage I crack propagation,7* the low strain fatigue lives of both wavy and planar slip materials should be increased with decreasing temperature. This follows because both materials show increased slip homogenization in this strain regime."13 Consequently, crack nucleation in intensified bands will be delayed and the linking of such small cracks into larger stage I cracks will be difficult. In addition, the blunting process required to lengthen a stage I crack from the order of 2 to 10 (where the strain concentration of the crack begins to overcome the slip homogenization property of the material) will also be retarded. These delays will give rise to longer lives in both kinds of material. In contrast to the blunting hypothesis, no temperature dependence has been predicted on the basis of the cell structure hypothesis, because it is well-known that materials cycled at low temperature show no differences in type of dislocation structure for a given strain amplitude.18"20 If the lives of wavy and planar slip materials do show a temperature dependence when the environment is eliminated as a variable, then it is questionable whether cell structures per se have a fundamental role in fatigue fracture. Accordingly, specimens of copper and Cu-7.9 wt pct A1 have been cycled at 298° and 77°K in vacuo and the fatigue lives compared with those in air and in liquid nitrogen, in order to establish whether or not there is a real temperature effect in low strain fatigue. Since it is difficult to measure the strains in specimens when cycled in vacuo, S-N curves have been used as the basis of comparison. In studying the influence of temperature on fatigue life in ordinary environment, Holt and Backofen2 used the superior basis of E-N curves. However, they also published S-N curves and thus established the relationship between E-N and S-N curves. This relationship is used to support the S-N comparison reported in the present investigation. EXPERIMENTAL Materials. The copper employed in this investigation was of 99.99 pct purity and the cu-7.9 pct A1 was prepared from metals of the same purity. The stock, of 3 in. initial diam, was reduced in size by rolling

Jan 1, 1969

By Michael A. Toole, O&apos

INTRODUCTION The tremendous capital investment required to produce a low grade ore deposit demands a reliable answer to the question: "How much does it cost to drill a well to produce the uranium that geologists have indicated is there in the ground?" However, you will find the answers given will be many and varied, depending on whether they come from the operating company, the drilling contractor, a geologist, a reservoir engineer, purchasing agent, or whoever. Each generally considers only a limited area of the total operation. The operating company usually depends upon the drilling contractors, service companies, and consultants to supply expertise. Because it is often difficult to see the "whole picture" or even to agree upon what the "whole picture" is, planning a well program and its costs is often done piecemeal. Frequently, costs "saved" in one area of the program are needlessly spent in another, because the effect of one area upon the other was overlooked. Since the drilling fluid is such an influential part of the drilling program, it should be given utmost consideration when planning the overall program. As W. D. Lacabanne wrote in 1954: "The drilling fluid system is understandably called the heart of the rotary oil drilling rig. Any other type of rotary rig.... should benefit by the incorporation of mud fluids in the drilling scheme." And G. R. Gray mentions that "The driller recognizes the drilling fluid as one of the useful tools available to solve drilling problems." However, in minerals drilling, only in recent years has the drilling fluid been considered as more than a tool to get through special problem areas. Although there are many similarities between drilling for oil and gas and drilling for minerals, the differences in the drilling equipment used justifies designing specific fluids for the minerals drilling industry. NL Baroid/NL Industries, Inc. has been a leader in introducing such fluids and in providing technical know-how to the minerals drilling industry. The purpose of this paper is: (1) to discuss the selection of drilling fluids to meet specific drilling conditions during both exploration and production and (2) to show the interrelationship among factors present in the exploration and production phases that influence total well costs. DRILLING FLUIDS FOR DRILLING PROBLEMS The drilling fluid is a tool that can be used to improve drilling performance by improving hole cutting, cleaning, stability, and formation productivity. Properly formulated and maintained drilling fluids enable the drilling operation to be carried out with increased efficiency and lower total (overall) costs. However, it should be noted that not all drilling problems can be solved by even the most carefully prepared and maintained drilling fluids. Of the many possible drilling problems encountered in a well before reaching target depth, this paper will discuss only those most likely to be present in the shallow [61 to 610 m (200 to 2000 ft)] drilling operations in South Texas. LOST CIRCULATION Loss of circulation is the most common problem encountered in drilling. Because the losses occur under varied conditions, it is often difficult to determine the exact causes. "Lost circulation" or "lost returns" means the partial or complete loss of drilling fluid to voids in the formation. "Loss of water" while drilling with water may take place into any permeable section and should be distinguished from "water loss" or filtration of fluid through the filter cake of mud solids laid down on a permeable formation. "Loss of water" can frequently be stopped by the addition of colloidal sized clay particles such as high yield bentonites, whereas "water loss" may be controlled with organic polymers. Subsurface conditions that lead to loss of circulation can be classified as: (1) natural fractures, (2) induced fractures, (3) unconsolidated or highly permeable formations (loose gravel), and (4) cavernous formations (crevices and channels). Loss of circulation may occur whenever the borehole pressure exceeds the formation pressure. The greater the differential pressure, the more likely it is that circulation may be lost. To stop loss of whole mud, voids must be bridged so that a filter cake can be laid down on the permeable section. The plugging material must be of the proper size and shape to offer greater resistance to the fluid flow around it than the flow up the annulus. A plugging composition that satisfies these requirements may not be able to be handled by the small rig pump available.

Jan 1, 1979

By W. M. Weigel

The first successful use of the wire saw in slate quarrying in the United States was late in 1926, at the quarry of the Colonial Slate Co. near Wind Gap, Pa. This installation was sponsored and supervised by the United States Bureau of Mines in collaboration with the National Slate Association.' The success of this trial resulted in other installations of wire saws, so that 27 were in operation at Pennsylvania slate quarries2 by October, 1928. Marble Quarrying with a Wire Saw Until recently, little or no attempt has been made to use the wire saw in the quarrying of other stone, but it is believed that its successful use in slate will be followed by attempts to take advantage of its possibilities in other quarrying operations. An example of such a trial is the recent installation of a wire saw at the marble quarry of the Saint Clair Marble Co. near Guion, in the Ozark region of northern Arkansas. This quarry is in a comparatively new district and the decision to open and develop it had to be made in the face of many unknown factors. For this reason, it was essential that the development costs be held at a minimum, and as a wire saw could be installed more cheaply than standard channeling equipment, it was decided to try it out. One factor Largely controlling the decision was that the location was peculiarly adapted to this method. The point of development selected was on the rather abrupt end of a ridge formed on the south by an almost perpendicular bluff along the White River and on the north by a rather steep slope with little or no overburden. By taking advantage of this topography it was possible to place the supporting standards for the sheaves at both the outer and driving end without the necessity of drilling or excavating openings to receive them, and to locate the motive power in line with these standards, which made it unnecessary to deflect the sheaves.

Jan 1, 1931

By R. W. Hertzberg, F. D. Lemkey, J. A. Ford

The technique of unidirectional solidification has been applied to the A1-AI3Ni and A1-CuAl2 ezltectic alloy systems; the controlled microstructure of A1-A3Ni consists of parallel A13Ni whiskers emhedded in an aluminum matrix while the Al-CuAl2, system solidifies as parallel alternate lamellae of aluminm and CuAl2. Mechanical tests (tension and flexure) have shown that the particle-matrix interface bond formed during unidirectional solidification allowes for efficient load transfer from the matrix to the reinforcing phase. Strength and fracture characterstics of the alloys were studied as a function of phase orientation; the tensile strength of controlled Al-Al3Ni samples was 43,000 psi (three times greater than that of as-cast specime~s). The strength of the Al-CIA2, cutectic was studied as a function of lamellae-flexure stress-axis orientation using a microbend apparatus. A twofold increase in outer fiber stress was observed as the lamellae were rotated from a position of no reinforcing (perpendicular to the stress axis) to one of maximum reinforcing (parallel to the stress axis), The brittle reinforcing constituent in each alloy (A13Ni and CuAl2) was observed to he the nucleating phase for fracture. It is to be concluded from this investigation that unidirectionally solidified eutectic alloys have a potential use as reinforcing coniposite) materials. In a recent review article, Chadwick1 has described the work of many investigators in the area of controlled solidification of binary eutectic alloys. Thus far, more than twenty eutectic alloys have been unidirectionally solidified to produce structures consisting of two phases in the form of alternating lamellae or as whiskers embedded within a continuous matrix; in either case, the phases are aligned parallel to the growth direction. In particular, Kraft and Albright2 have shown that the Al-CuA1, eutectic alloy exhibits a lamellar microstruc- ture as a result of unidirectional solidification while Lemkey, Hertzberg, and Ford3 have studied the A13Ni whisker-aluminum matrix morphology in the A1-A13Ni system. Whether these alloys could exhibit reinforcing behavior would have to depend upon the strength and volume fraction of the reinforcing phase (AI3Ni and CuA12) and the nature of the bond between the reinforcing phase and the matrix. Hertzberg and Kraft4 have shown that the interface bond between chromium whiskers and a copper matrix in unidirectionally solidified Cu-Cr is particularly good while Lemkey and Kraft5 have reported chromium-whisker tensile strengths in excess of 1,000,000 psi. However, with the chromium volume fraction being less than 2 pct, no reinforcing behavior was displayed by the Cu-Cr alloy.6 In view of the encouraging results concerning the good interfacial bond and high strength of the reinforcing phase in the Cu-Cr system and preliminary mechanical test data reported by Lemkey et al.3 for the A1-A13Ni system, the A1-CuA1, and A1-A13Ni eutectic alloys containing 50 and 10 vol pct, respectively, of the reinforcing phase give promise of possessing mechanical reinforcing behavior. Based on this premise, the objective of the investigation was to study the strength and fracture behavior exhibited by these anisotropic microstructures. EXPERIMENTAL PROCEDURE Controlled Solidification Procedure. An extensive description of the technique of unidirectional solidification has been presented elsewhere.' However, the pertinent details for each eutectic system studied are discussed below. Al-A13Ni System. Several master heats of this alloy were prepared by vacuum-induction melting in an A12O3crucible and casting in SiO2 mold or by induction melting in alumina crucibles under argon. The initial heats were prepared from 99.99 pct A1 and 99.99+ pct Ni, while later heats used 99.999+ pct A1 and 99.99+ pct Ni. Specimens of these master heats were unidirectionally solidified using induction and resistance heating sources and argon atmospheres at growth rates from 1.1 to 28.7 cm per hr. The thermal gradients in the liquid were controlled in the range of 26" to 36°C per cm for these runs. Al-CuA12 System. The master heat and controlled

Jan 1, 1965

By Harry T. Davis, Jasper L. Stuckley

The object of this paper is to record and interpret field and laboratory observations made by the writers during five years of study of the barite deposits of North Carolina. Deposits of barite are known to occur in three localities in North Carolina (Fig. 1) two of which—the Hot Springs and Kings Mountain —contain material of economic value. The Hot Springs area begins near Bluff, some 6 miles south of Hot Springs, and continues northeast by Stackhouse; a total length of 7 miles. The Kings Mountain deposits lie along a belt that extends from the north end of Crowders Mountain in a southwestward direction, along the east side of this and Kings Mountain, to Kings Creek, South Carolina. The third locality is 3½ miles southeast of Hillsboro, Orange County, a short distance west of the highway leading from Hillsboro to Chapel Hill. It is not known when barite was first discovered in North Carolina, but production from the Hot Springs area began some 50 years ago. The state has never produced large quantities of barite—usually there have been less than three producers—and definite figures are not available, but reasonably reliable estimates indicate a total production of 300,000 tons. From 1901 through 1920 barite mining was on a seemingly prosperous basis and a large tonnage was shipped from the Hot Springs and Kings Mountain areas. With the depression of 1920 the industry began to decline and production practically ceased in 1926. Geology of the Barite Areas In the Hot Springs area barite is found in the Max Patch granite of Archean age and the Snowbird formation of Cambrian age. The Max Patch granite is of two varieties, one gray to whitish and the other red. The gray granite is coarse, at times porphyritic, and composed of quartz, orthoclase and plagioclase feldspar, with a little biotite and muscovite. The red granite is also coarse and differs from the other only in having conspicuous pink and red feldspar. Both varieties have been much metamorphosed and weathered in places, so that they contain secondary

Jan 1, 1935

By Harry T. Davis, Jasper L. Stuckley

The object of this paper is to record and interpret field and laboratory observations made by the writers during five years of study of the barite deposits of North Carolina. Deposits of barite are known to occur in three localities in North Carolina (Fig. 1) two of which—the Hot Springs and Kings Mountain —contain material of economic value. The Hot Springs area begins near Bluff, some 6 miles south of Hot Springs, and continues northeast by Stackhouse; a total length of 7 miles. The Kings Mountain deposits lie along a belt that extends from the north end of Crowders Mountain in a southwestward direction, along the east side of this and Kings Mountain, to Kings Creek, South Carolina. The third locality is 3½ miles southeast of Hillsboro, Orange County, a short distance west of the highway leading from Hillsboro to Chapel Hill. It is not known when barite was first discovered in North Carolina, but production from the Hot Springs area began some 50 years ago. The state has never produced large quantities of barite—usually there have been less than three producers—and definite figures are not available, but reasonably reliable estimates indicate a total production of 300,000 tons. From 1901 through 1920 barite mining was on a seemingly prosperous basis and a large tonnage was shipped from the Hot Springs and Kings Mountain areas. With the depression of 1920 the industry began to decline and production practically ceased in 1926. Geology of the Barite Areas In the Hot Springs area barite is found in the Max Patch granite of Archean age and the Snowbird formation of Cambrian age. The Max Patch granite is of two varieties, one gray to whitish and the other red. The gray granite is coarse, at times porphyritic, and composed of quartz, orthoclase and plagioclase feldspar, with a little biotite and muscovite. The red granite is also coarse and differs from the other only in having conspicuous pink and red feldspar. Both varieties have been much metamorphosed and weathered in places, so that they contain secondary

Jan 1, 1935

By Kenneth A. Gutschick, Robert S. Boynton

Lime has become a general and loosely used term to denote almost any kind of calcareous material or finely divided form of limestone or dolomite, as well as burned forms of lime. However, according to Webster, lime is only calcined limestone (known as quicklime, unslaked lime, or calcium oxide). It also embraces the secondary product of quicklime, i.e., hydrated lime or slaked lime (calcium hydroxide). There are two basic types of limestone used for lime manufacture-high calcium and high magnesium (dolomitic). The dolomitic quicklimes and hydrated limes correspond to their "high calcium" counterparts. The only difference is that the dolomitic types are a combination of the elements calcium and magnesium, in varying percents, whereas high calicum limes contain less than 5% MgO down to 1/2%. In either case a pure form of limestone of at least 97% combined carbonate content is needed to make salable lime, barring a few exceptions. The calcination of both types is diagrammed chemically as follows: [ ] In the foregoing reversible reactions the limestone is burned (calcined) in lime kilns, with the carbon dioxide content of the stone expelled as a gas. The weight loss during calcination of pure high calcium limestone is 44%; with equimolecular dolomitic limestone, the weight loss is 48%. Since lime has a strong affinity for CO_, particularly if moisture is present, it will readily revert to its original carbonate form. This occurs when quicklime "air-slakes" and adsorbs CO.. from the air. Thus, quicklime is perishable and should be stored in dry, water-tight areas. Depending upon the type of kiln used and the physical structure of the stone, the size of the quicklime may range from sandlike granules to 8 in. lumps. However, pebble sizes ranging from 1/4 in. to 2 in. are the most common. Screened quicklime fines are also com¬pressed (pelletized) into 1 in. pellets. For some purposes ground or pulverized forms of quicklime are used, ranging from No. 10 mesh to dust. Generally a pebble of quicklime is about the same size as the pebble of limestone before calcination (perhaps shrinking slightly). A more stable form of lime is hydrated lime. This is obtained by adding water to quicklime, slaking it into a dry, fine, subsieve size white powder. Because its affinity for moisture has been satisfied, it is not vulnerable to further moisture like quicklime. However, it has the same strong affinity for CO_. The following reversible chemical reactions illustrate how hydrated lime when heated (or dehydrated) can revert to the original oxide form:

Jan 1, 1975

By Donald A. Corrigan, John Chipman

It is shown that the heat of solution of nitrogen in liquid-iron alloys is Proportional to the interaction coefficient. This proportionality forms the basis for a method of predicting nilrogen solubility at any temperature when the interaction coefficient is knoun at 1600°C ov when the solubility is known at some one temperature. A method for predicting the solubility of nitrogen in liquid steels, including alloy steels, was proposed some years ago by Langenberg.' Since the data available at that time were restricted to temperatures of about 1600°C, his predictions were similarly restricted. More recently, Nelssonz devised an approximate method for estimating nitrogen solubilities at higher temperatures. It is the purpose of the present paper to present a method by which the solubility of nitrogen at any temperature within the steelmaking range may be predicted from the known interaction coefficients at 1600°C. Nitrogen in iron and in all of the alloys to be considered here is known to obey Sieverts' Law; hence the activity of nitrogen in an alloy of fixed composition is proportional to its concentration, here expressed in weight percent. The activity of nitrogen is defined as equal to its weight percent in the binary Fe-N solution at any temperature. Its activity coefficient in any alloy is the comparison being made at equal values of T and PN2. In all alloys the activity coefficient changes with composition, log fN being a linear function of the percent of alloying element at low concentrations. In the following calculations the alloy compositions are restricted to those in which this linear relation is exhibited. For most systems this is a fairly wide range, for example up to 5 pct V and to 10 pct Cr or Ni. For this composition range. complex alloy is the same as that in the Fe-N-j ternary solution. Langenberg's method of prediction was based on Eq. [3], the values of log fN for various additions being taken from a graph. Instead of using the simple addition indicated in Eq. [3], he used a more complex method suggested for Fe-S-j alloys by Morris and Buehl.3 For the composition ranges in which Eq. [2] is valid the two methods are equivalent. Nelson extended the prediction to other temperatures on the assumption that logfN is inversely proportional to absolute temperature. It may be shown that inverse proportionality would result if the partial molal entropy of nitrogen were unaffected by addition of the alloy element, an assumption which Nelson designated as a "regular" solution. It has been shown recently by the authors4 that this assumption is not a good approximation. The heat of solution of nitrogen (N2) in an alloy may be obtained if the solubility is known as a function of temperature. Measurements of this nature have been reported recently by Beer5 for Fe-Mn alloys, by Nelsson2 for Fe-C, by El Tayeb and parlee6 for Fe-V, and by Pehlke and Elliott7 for many alloys embracing a wide range of compositions. In connection with the work of the last named authors it is noted that their Fig. 22 gives the heat effect per half mole rather than per mole of N2. In using their data we have shifted some of their values slightly by using the best straight line in preference to their curve. Their data, supplemented by others from the literature, are summarized in Table I. In Fig. 1 the heat of solution of nitrogen is shown as a function of composition for the several alloy systems. The difference between the heat effect in the alloy. AH; and that in pure

Jan 1, 1965

By A. V. UDELL

OF all the metals that have from time to time been called the "Wonder Metal," mercury, often called quicksilver, is probably the most deserving of this designation. A wonder metal it must have been to those workers of an earlier day who named it after that Latin god of commerce and gain, characterized as the fleet messenger of the gods and the conductor of souls to the lower world. The word mercury has been used to indicate a carrier of tidings, a bearer of news, a nimble or clever person, a hawker, and a skillful thief. All of these attributes, and more, are recognizable in this metal, the technical terminology of which is "Hydragyrum," meaning water-silver, and from which the chemical symbol "Hg" is derived. Fickle in its occurrence in nature, simple in its metallurgy, illusive in captivity, it serves man in life or death, in war or peace, in commerce, science and arts, in mining, agriculture, and forestry with a versatility found in no other element.

Jan 1, 1929

By O. B. Ellis

Although thousands of tons of stainless steel have been used successfully for many types of equipment, there have been few cases of failures due to the phenomenon described as stress corrosion cracking. During the past seven years only six cases of such failures have been drawn to our attention and investigated in the Research Laboratories with which the author is associated. These failures oc¬curred in two coffee urns, two wool con¬ditioning units, one dyeing machine, and another in a part of a steam-jacketed stock pot. In each case the equipment failed in a comparatively short time after exposure to conditions of high humidity at tempera¬tures in the range of 100 to 200 F. The failures in all cases were characterized by general embrittlement and cracking of the stainless steel, with only slight indications of general corrosion except at the cracks. The first failure of this type was a coffee urn returned for investigation in 1937. The top and bottom sections showed a general corrosive attack and embrittlement and cracking of the stainless steel. The chemical analyses of these sections were as follows:

Jan 1, 1945

By Sydney H. Ball

A QUARTER of a century ago, a pessimistic Belgian financier in conversation with the founder of the Belgian Congo, that great ruler, Leopold II, emphasized the danger to the colony should the synthesis of rubber be discovered. The king replied, "I do not worry. The Congo has had its ivory period; it now has its rubber period. Tomorrow it will have that of its mineral wealth; eventually that of agricultural products." That "tomorrow" arrived some twenty years ago. Through her mines the Belgian Congo has survived the present depression, and her mines for the next decade will safeguard her. The Congo, in turn. is the surest foundation industrially and financially of Belgium itself. In few, if any, political units is mining as dominant as in the Belgian Congo. In 1930, 1931 and 1932 mineral products represented respectively 67.9 per cent. 70.5 per cent and 59.3 per cent, of the total exports. In 1933 for each white person in the colony, there was produced about $1,675 worth of gold, diamonds, copper, tin ore and minor mineral products and in 1930 the per capita production, notwithstanding the larger population, was almost $2,000.

Jan 1, 1934

By Sidney Powers

Discussion of the paper of SIDNEY POWERS and ALFRED C. LANE, presented at the New York meeting, February, 1916, and printed in Bulletin No. 110, February, 1916, pp. 535 to 548. N. L. BOWEN, Washington, D. C. (communication to the Secretary*). -This detailed study and. complete demonstration of differentiation as a result of the sinking of crystals has a great general significance in petrogenesis. If this action can be demonstrated in an effusive body, even though a very thick one, how can one doubt its possibility in large intrusive bodies? The authors speak of the sinking of augite and the rising of plagioclase but I should consider that they should depend entirely on the former action to obtain their results. It is true that in my experiments, to which the authors refer, a floating of crystals was in one case obtained, viz., in the case of tridymite crystals, but it must be remembered that tridymite has an exceptionally low density. Plagioclase crystals, on the other hand, are of nearly the same density as basaltic liquid. Under magmatic conditions they might be a little heavier than the liquid or a little lighter, we do not know which, but the margin would be exceedingly small and any motion resulting, whether upward or downward, would be correspondingly small in the usual case. For this reason I should think that the sinking of pyroxene should be considered probably the sole factor in producing the observed result, for which purpose it appears to be entirely adequate. The measurements of grain have also a certain significance in this connection. In the experiments referred to a difference of grain was obtained in different parts of the charge, which was entirely independent of the rate of cooling but connected with the fact that a sinking crystal does not depend entirely upon diffusion for the collection of its material from the surrounding liquid. The crystals which sank a considerable distance were therefore exceptionally large. Now in the Cape Spencer flow the augite crystals are normally (top and bottom) somewhat smaller than the plagioclase crystals, but in the layer somewhat below the middle,

Jan 5, 1916