Search Documents

By R. M. Brick, M. A. Williamson

CERTAIN features of the response of copper and brass to deformation and recrystallization remain obscure. The textures obtained on rolled sheet are listed by Schmid and Boas1 as: No adequate explanation has been advanced for the presence of the secondary deformation texture of copper and its absence in brass or for the origin of the cubic recrystallization texture of copper.2 A recent publication3 attempted to rationalize the above empirically described annealing texture of brass on the basis of retention of the (110) [112] rolling orientation plus twinning about the central octahedral poles of the usual secondary (110) [115] orientation. The difference in the textures of annealed copper as compared to 70-30 brass is also shown by the difference in the position of ears for drawn copper, at o° and 90°, as compared with drawn brasses, at 45°, for all compositions between 90-10 and 70-30.4 Data on individual crystals are as yet too few to permit of an analysis of these textures comparable to that of mild steel as made by Barrett and Levenson.5 EXPERITMENTAL METHODS The materials studied included copper specimens cut from the central, equiaxed crystal portion of a tough-pitch wirebar; brass made from this copper and high-purity (99.99 per cent) zinc including alloys of 7 per. cent, 15 per cent, 24 per cent, 29 per cent and 36 per cent Zn and large single crystals of 70-30 brass. Sections ¼ in. thick of the cast polycrystalline copper and brasses were reduced 40 per cent by rolling, recrystallized to a common grain size of 0.045 mm. and then rolled directly to foil 0.002 in. thick. Hardness readings employing both the Vickers and Rockwell machines were taken at intervals during the reduction. For comparison, similar specimens were cross-rolled-i.e., turned through 90 for each pass-and comparable hardness data were secured. Finally sections from the single crystals of brass were cut to obtain the following initial orientations; these sections were rolled, hardness data secured and a complete micrographic record of structural changes obtained:

Jan 1, 1941

By G. A. Moore

A brief review is given of methods designed to produce metallic iron of high purity, and typical results are listed. A recent method, utilized at the National Bureau of Standards, consists of the extraction of ferric chloride by ether, reduction of this ferric chloride to ferrous chloride, further purification of this chloride, and the subsequent electrolytic deposition of metallic iron. iron produced by this procedure apparently is softer than, and otherwise different in properties from, any iron previously prepared and contains appreciably smaller amounts of impurities. THE history of attempts to produce "pure" iron reaches to antiquity and it may be presumed that each ancient armorer who succeeded in making a better steel concluded, correctly, that he had done a better job of removing the "base metals," and incorrectly, that he now at last had a "pure" metal. Early metallurgical papers mentioned use of "pure iron" in making alloys—this "pure" iron in most cases being inferior to some commercial stocks of the present time. Improvement has been continuous, and usually at a sufficient rate to convince each succeeding group of workers that they, at last, were using the really pure metal (until the analysts also improved their techniques to again discover the impurities). These adventures were reviewed in some detail by Cleaves and Thompson.' Although the ores of a metal may be abundant, difficulties in extracting it may make the pure metal very rare. When impurities are restricted to a total of a few parts per million, nearly all pure metals become rarities. Lead, copper, gold, mercury, silver, zinc, aluminum, bismuth, and the six platinum metals are claimed to be available with total impurities ranging from 2 to 50 ppm. The present small and scattered world supply of so-called "pure" iron holds an unimpressive place in another group of 16 metals having approximately 100 ppm of foreign material. Of about 20 less rare metals, only the platinum metals are more costly to prepare. While the production of such rare varieties of iron may appear insignificant in the presence of thousand-ton operations with 95 to 99 pct metal, it must be emphasized that all researches on commercially interesting irons and steels are in fact studies of the modifications of the properties of iron by additional materials. Until the properties of high purity iron are directly measured, all ferrous research must operate without known base values. Traces of impurities may affect the properties of a metal in many ways. Infinitesimal traces of solutes, by disturbing the electronic configuration, greatly change the electrical properties of transistors and semiconductors2-3 and slightly larger traces might alter these quantities in iron. Soluble impurities which disturb the perfection of lattice arrangement not only may alter the magnetic constants and electric properties, but by their close association with dislocation phenomena probably control the very existence of the "yield point"; determine the value of yield stress; and perhaps control the selection of slip and cleavage planes. It has been speculated that impurities might even cause the allotropic transformation in iron, but in any case their rearrangement must contribute to the unreliability of heat capacity and other thermodynamic measurements. Impurities which do not remain in solution may cause even greater effects on the properties. Microscopically visible amounts of phases other than ferrite can be found in all high purity irons which have come to my attention. It can be calculated that from 50 to as little as 2 ppm of an insoluble material might be sufficient to completely film all grain boundaries in irons having grain sizes from ASTM Nos. 10 to 1. Should this occur, such films, even though invisible, may be very important in fracture problems, especially at extremes of temperature:' Studies of grain growth and diffusion normally imply consideration of a single-phase system, hence, in the presence of insoluble impurities they can be expected to give ambiguous data." High purity iron is also in demand for use as chemical and spectro-chemical standards; for work in classifying the lines of the iron spectrum; for biological work in nutrition; and for work in nuclear physics. where the presence of some sensitive

Jan 1, 1954

By J. F. Myers, S. E. Sharp

The safety data presented in this paper are based upon replies to a Questionnaire sent out to representative mining companics. The authors feel that it is a fair cross section of the milling industry, in that the 17 companies, of the United States and Canada, reporting on 22 mills, are scattered from the Hudson Bay to the Mexican border and from coast to coast. These data concern the accident records of the various plants from 1939 to 1944, inclusive and the six years are divided into two periods. The first period (1939, 1940 and 1941) represents something of a normal operating condition. The second period (1942, 1943 and 1944) represents the period of time that was most affected by war conditions. During the second period there was a high labor turnover, inexperienced workers were numerous, women replaced men in many kinds of work, a labor shortage existed more or less throughout the industry, and supervision was pushed for peak production. All of the companies reporting compiled their accident experiences for these six years in accordance with the standards set up by the American Standards Association (New York, N. Y.), consequently the tabu lated data presented herein are comparable. The authors of this paper feel that the industry as a whole is greatly indebted to the personnel of the companies that furnished these data, which make this study possible for presentation. This survey covers a total exposure of 74,528,880 man-hours, with 105,471 man-days of lost time from 870 accidents. Safety Records In Table I, the safety record is shown of the various mills reporting. The severity rate is usually conceded to be the most vital statistical figure in safety parlance, therefore the participating companies are listed in order of their severity rate for the combined six-year period, under size of organizatiori. The table also shows the frequency rate as well as the frequency-severity ratio (F/S). As noted in Table I, most of the companies suffered an increase in both severity and frequency rates during the second period; only six of the 22 enjoyed an improvement. From correspondence with the various plants, it seems that a few had very little labor shortage or turnover, and these were not greatly affected. A few plants, anticipating the situation, strengthened their training facilities and actually were able to show a better experience during the second period. This gives great credence to the value of organized training in any safety program. The frequency-severity ratio (F/S) shown in the last column of Table I offers

Jan 1, 1947

By S. E. Sharp, J. F. Myers

The safety data presented in this paper are based upon replies to a Questionnaire sent out to representative mining companics. The authors feel that it is a fair cross section of the milling industry, in that the 17 companies, of the United States and Canada, reporting on 22 mills, are scattered from the Hudson Bay to the Mexican border and from coast to coast. These data concern the accident records of the various plants from 1939 to 1944, inclusive and the six years are divided into two periods. The first period (1939, 1940 and 1941) represents something of a normal operating condition. The second period (1942, 1943 and 1944) represents the period of time that was most affected by war conditions. During the second period there was a high labor turnover, inexperienced workers were numerous, women replaced men in many kinds of work, a labor shortage existed more or less throughout the industry, and supervision was pushed for peak production. All of the companies reporting compiled their accident experiences for these six years in accordance with the standards set up by the American Standards Association (New York, N. Y.), consequently the tabu lated data presented herein are comparable. The authors of this paper feel that the industry as a whole is greatly indebted to the personnel of the companies that furnished these data, which make this study possible for presentation. This survey covers a total exposure of 74,528,880 man-hours, with 105,471 man-days of lost time from 870 accidents. Safety Records In Table I, the safety record is shown of the various mills reporting. The severity rate is usually conceded to be the most vital statistical figure in safety parlance, therefore the participating companies are listed in order of their severity rate for the combined six-year period, under size of organizatiori. The table also shows the frequency rate as well as the frequency-severity ratio (F/S). As noted in Table I, most of the companies suffered an increase in both severity and frequency rates during the second period; only six of the 22 enjoyed an improvement. From correspondence with the various plants, it seems that a few had very little labor shortage or turnover, and these were not greatly affected. A few plants, anticipating the situation, strengthened their training facilities and actually were able to show a better experience during the second period. This gives great credence to the value of organized training in any safety program. The frequency-severity ratio (F/S) shown in the last column of Table I offers

Jan 1, 1947

By Paul Hett

The much-heralded Deep Ruth operation of Kennecott Copper Corp., at Ruth, Nev., is scheduled to become a producer by 1957. Inaugurated as a project in 1951, production was originally scheduled to start in 1953, but excessive water hindered shaft sinking. A revised schedule called for output by 1955, but again plans had to be changed. This time the change was to permit mining of an orebody that would have otherwise been lost because of block caving methods planned for the main deposit. The new ore is within the cave limits of the larger orebody, above the first production level. Ore will start coming from this new source in 1956, a year ahead of the principal operation. (See NEWS, page 344.) There is little doubt that current economic conditions and unforeseen expenditures for early shaft development will make the Deep Ruth a high-cost producer. Yet, some of the drawbacks of the Kennecott operation may be mitigated by the possibility that additional exploration will increase the already assured 25 million tons of 0.83 pet copper ore. While Kennecott is missing out on the current high copper market and is thus left with a potentially narrowed profit, the predicted demand for copper has created an optimistic feeling. Its development is certain to enlarge known U. S. copper reserves and significantly extend the life of Kennecott's Nevada operations.

Jan 4, 1955

By Frank Schrader

J. DANA SPERR, Jerome, Ariz. (communication to the Secretary*).¬Very little accurate information has been published about this district. Most of the geological data appearing in the technical press are based on "careful observations" made from an auto stage and a casual glance through the U. S. Geological Survey Bulletins, No. 340 of 1908 or No. 397 of 1909, both by F. C. Schrader. Mr. Schrader's report is still the best publication on the district. A really careful study of this report will uncover only a very few statements which have since proven questionable. This is a remarkable record when it is considered that only a short time was spent by Mr. Schrader in the field and that there was very little development work done at that time. The mining world and especially Mohave County, Ariz., will feel a sense of gratitude to Mr. Schrader for revising his early report. on this

Jan 3, 1917

C. E. Dewey, Georgetown, Colo. (communication to the Secretary) : In his remarks on crushing-machinery, Mr. Douglas says (Twins., xxii., p. 322): "To insure a smaller and more uniform size of particles in the crushed material, the Dodge crusher still communicates motion to the upper extremity of tile movable jaw, which oscillates on fixed pivots projecting from its lower extremity!' The notion that, in order to obtain a fine and uniform product from a rock-breaker, the movable jaw must be pivoted at its lower extremity, seems to obtain generally among mill-men, as well as among manufacturers of machinery. My experience with machines of both types does not confirm this belief. It is true that, to obtain a uniformly fine product from a jaw-crusher, the stroke at the lower extremity of the crushing-surface must be short; but that the movement at that end must be less than at the other or receiving-end is, I think, an erroneous assumption. Figs. 1 and 2 are intended to illustrate the two types of machine. It is found in practice that the capacity and the nature of the product of either machine, as usually constructed, are governed by the opening, C D, and the length of stroke of the movable jaw at D. This being the case, machines of either type, of the same width of crushing-surface, running at the same speed, and having the same adjustment as to opening and stroke at D, should give, when fed

Jan 1, 1895

By J. E. Lawver, R. R. Beebe, J. L. Wright

This paper describes a separation coefficient Ks useful as a "measure of goodness" to be used in factorial and response surface methodology. The use and limitations of the separation coefficient is discussed, and a computer program for calculating the coefficient is presented (in Fortran). The application of the coefficient is illustrated in terms of electro-dynamic separation of Mesabi semitaconites. Present Mesabi wash ores and gravity concentrates with an iron to silica ratio of only 5 or 6 to 1 are no longer readily salable, for the steel industry now demands concentrates with an iron to silica ratio of at least 10 to 1 and a structure comparable to pellets. THE ELECTRODYNAMIC-FLOTATION PROCESS Wash ores and gravity concentrates consist largely of hematite, goethite, and quartz. Several methods of beneficiation are being tested at the University of Minnesota Mines Experiment Station with a view to improving the salability of these materials. A process that looks particularly promising from an economic view is the combination electrodynamic-flotation process shown in Fig. 1. This process is designed to upgrade gravity concentrates to a 5% silica content and to provide fines — from the flotation circuit —to permit agglomeration. Although electrodynamic concentration of specularite is an established and well-understood process, the electrodynamic concentration of Mesabi goethite-hematite gravity concentrates presents interesting and enigmatic problems. The gravity concentrates are by no means assemblages of clean, free mineral particles. Instead, the concentrates to be retreated consist of a great variety of middlings. More or less complete liberation would require grinding to minus 325 mesh, at which size only flotation could be expected to function, and even then grades and especially recoveries would not be satisfactory. A close examination of the gravity concentrates shows that grinding to 100% minus 48 mesh will produce a product which is approximately 70 weight % plus 325 mesh (see Fig. 1). The remaining 30 weight % can be deslimed and floated by conventional methods, but the resulting iron concentrate is

Jan 1, 1964

By E. T. Turkdogan, P. Grieveson

Experimental results are given for the rate of oxidation of ferrous iron to ferric iron in pure molten iron oxide by carbon dioxide + carbon moloxide mixtures at 1550°C. It is shown that the rate-controlling process is the interdiffusion of iron and oxygen atoms within the melt. The inter-diffusivity of iron and oxygen in the melt is obtained from the results and the value of (5.0 * 1.0) x 10-5sq cm per sec is recommended for the temperature of 1550°C. Similarly, it is also found that the rate of reduction of molten iron oxide is con -trolled by diffusion in the melt; however, apparent interdiffusivity values from these experiments are 10 to 20 pct higher than those obtained in the oxidation experiments, by virtue of convection arising from density difference. The results of the oxidation experintents are used to calculate an estimated self-diffusivity of iron in molten iron oxide of (1.5 * 0.5) x sq cm per sec. BECAUSE of the industrial importance of iron oxides, the study of the kinetics of both the reduction and oxidation of the solid oxides has received a great deal of attention. However, knowledge of the kinetics of similar reactions in the liquid state is very meager. Dancy 1 studied the kinetics of reduction of molten iron oxide by carbon in pig iron and found that the reaction is very fast. It was concluded from the results that the reduction of molten ferrous oxide is a first-order reaction up to 80 pct reduction, while

Jan 1, 1964

By Robert L. Thoms, Richard M. Gehle

Hydraulic fracturing is of considerable interest as a possible release mechanism during operation of storage caverns in salt formations. However, field data are lacking on fluid pressures required to initiate and propagate fractures over a range of depth in U.S. salt domes. A currently active research project is outlined which has the objectives of gathering field data on hydrofracture gradients in inland and coastal domes of the Gulf Coast. A wireline minifracturing system with downhole microprocessor controls is briefly described.

Jan 1, 1985

By V. D. Perry

Carlisle: Reno, let's start off by asking "When was the first day that you began working in your profession?" Sales: I began in Butte, Montana, on August 22, 1900 as an assistant engineer for the Boston & Montana Consolidated Copper and Silver Mining Co., and continued at that job for about a year. The general manager was C. S. Batterman, and the mines- Mountain View, Pennsylvania, Leonard, East Colusa, and one or two others-were part of Boston & Montana.

Jan 5, 1966

Elected Died 1895 ABBOTT, AI ATTHUR 1908 1882 ABBOTT, ARTHUR V 1906 1905 ABE, MASAYOSHI 1909 1903 ADAMS, CHARLES C. 1905 1906 ADAMS, JOHN C. 1913 1905 ADAMS, WILLAMS 1909 1903 ADAMS, W. EDWARDS 1910 1884 ADDY, MATTHEW 1896 1906 AFFLECK, WILLIAM A. 1911 1889 AKERS, WILLIAMS A. 1906 1905 ALABASTER, RUPPERT C. 1911 1899 ALBERGER, LOUIS R. 1911 1894 ALLEN R B 1896 1905 ALLEN, R. SCOTT 1906 1886 ALLISON, ROBERT 1916 1874 AMIOT, H. 1892 1886 AMSLER, CARL 1894 1898 ANDRSON, JOHN W 1905 1895 ÅNGSTROM, CARL 1901 1887 ARCHBALD, JAMES 1910 1900 ARLETT, GEORGE H 1906 1895 ARMSTRONG, JOHN F 1898 1882 ARNOLDS, HUGO 1886 1875 ASHBURNER, CHARLES A 1889 1872 ASIIBURNER, WILLIAM 1887 1883 ATKINS, C M , JR 1885

Jan 1, 1917

By A. C. England, William F. Haney, Paul B. Crawford, Bobby L. Landrum

The creation of unsymmetrical vertical or horizontal fractures in a producing well will result in a unique distortion of the normal shut-in pressures existing at the four surrounding wells. An electrical model study has been made to show how the shut-in pressures at the wells surrounding the fractured producing well may he used to estimate the size and orientation of vertical or horizontal fractures. The pressure differences at the four surrounding wells are recorded during production from the fractured well. The resulting pressure dato are matched from a table of several hundred possible fracture combinations. The table refers to the figure showing the effective size and orientation of the commercially created fracture. INTRODUCTION The creation of commercial fractures about oil and gas wells has led to considerable speculation as to the size and shape of the fractures. It is important that the size and shape be known in certain instances, especially when pressure maintenance programs are to be initiated. It was shown that if knowledge of a vertical fracture could be found that such information may be utilized in planning a waterflooding or gas cycling program and that in some cases the fractures might be utilized very effectively.' Other work showed that it may be desirable to create "pancake" fractures in certain reservoirs but that they should exist in a desirable range.' If the fractures are too large, they should be plugged prior to initiating a pressure maintenance program. If an irregular shaped "pancake" fracture is created, it is desirable to know the orientation of this fracture because similar but unreported studies have shown that "pancake" fractures may or may not substantially affect the sweep efficiencies and performance of the flooding or cycling program. Consequently, it may be desirable in some instances to estimate the effective size and orientation of the fracture. ANALOG An electrical model was used in making this study. The electrical model consisted of a circular reservoir approximately 8 in. in diameter, 1 in. thick and was filled with a dilute salt solution. A copper band formed the periphery of the reservoir. A vertical fracture was simulated by a copper strip soldered to the wire well located in the center of the reservoir. Vertical copper strips of various lengths and orientation were soldered to the wire well to represent vertical fractures in the reservoir. In studies reported here on vertical fractures it was arbitrarily assumed that two fractures originated at the well and extended out into the reservoir. An electrical potential was imposed between the wire well and the periphery of the tank. Plots of the iso-potentials are shown in Figs. 1 through 9. This model provides the steady-state isopotentials existing in a uniform, homogeneous circular reservoir having a vertically fractured well at its center. The permeability of the fracture is much greater than the permeability of the matrix proper. The effects of gravity are neglected. In preparing Tables 1 and 2, four symmetrically located unfractured wells were assumed to exist around

Jan 1, 1956

By D. M. Davidson

The drill sampling and evaluation of the Piney River ilmenite property was carried out during the early part of 1944 by E. J. Longyear Co., using the company's standard core-drill outfits to complete 44 holes to an average depth of IIO ft., from which were collected 1100 samples. The Piney River ilmenite-apatite lode is 25 miles north of Lynchburg, in Nelson and Amherst Counties, Virginia (Fig. I). Its elevation is about 900 ft. above sea level and it lies in the old pre-Cambrian complex of crystalline rocks that make up the Piedmont physiographic province lying east of the Blue Ridge Mountains. The terrain is gently rolling and well watered and is drained by the Piney and Tye Rivers, which are tributary to the James. Geology The Piney River ore body comprises the upper, weathered part of a tabular basic rock, which occurs in a large area of granite-gneiss. The section containing profitable ore is about 3000 ft. long. It is separated naturally by thinning, into northeastern and southwestern segments with widths of 300 and 100 ft. respectively. The dip averages 4.5° southeast but steepens locally (Figs. 2 and 3). The unaltered rock is an even, granular mixture of feldspar, ilmenite, and apatite, to which Watson1 gave the name Nelson-ite. The decomposed ore body, which is now being exploited by open cut, is a yellowish clay material in which black ilmenite and glassy apatite are the only conspicuous minerals. An economically important structural feature of the deposit is a banding of minerals coinciding with the dip and strike of the dike. This is more pronounced in the footwall of the northeastern part of the intrusive, where there is also a higher than average concentration of ilmenite. According to Watson,' the TiO2 content of the Nelsonites of this region ranges from 10 to 42 per cent, while P205 varies from 4 to 15 per cent. It is inexpedient at present to disclose exact metal content of the Piney River ore body; suffice it to say that the average tenor lies well within the extremes noted by Watson. Sampling Methods and Procedure During a preliminary inspection of the ore body, Longyear engineers surmised that because of its soft, clayey character, drill sampling would yield little core, therefore they made all possible preparations to procure accurate samples of the drill cuttings, or sludge. The first requisite in obtaining representative drill cuttings is to secure their full recovery. Only under certain conditions, and by employing a most careful and rigid sampling technique, is this pos sible. There must be no loss of the water circulating in the hole, and the velocity

Jan 1, 1949

By D. M. Davidson

The drill sampling and evaluation of the Piney River ilmenite property was carried out during the early part of 1944 by E. J. Longyear Co., using the company's standard core-drill outfits to complete 44 holes to an average depth of IIO ft., from which were collected 1100 samples. The Piney River ilmenite-apatite lode is 25 miles north of Lynchburg, in Nelson and Amherst Counties, Virginia (Fig. I). Its elevation is about 900 ft. above sea level and it lies in the old pre-Cambrian complex of crystalline rocks that make up the Piedmont physiographic province lying east of the Blue Ridge Mountains. The terrain is gently rolling and well watered and is drained by the Piney and Tye Rivers, which are tributary to the James. Geology The Piney River ore body comprises the upper, weathered part of a tabular basic rock, which occurs in a large area of granite-gneiss. The section containing profitable ore is about 3000 ft. long. It is separated naturally by thinning, into northeastern and southwestern segments with widths of 300 and 100 ft. respectively. The dip averages 4.5° southeast but steepens locally (Figs. 2 and 3). The unaltered rock is an even, granular mixture of feldspar, ilmenite, and apatite, to which Watson1 gave the name Nelson-ite. The decomposed ore body, which is now being exploited by open cut, is a yellowish clay material in which black ilmenite and glassy apatite are the only conspicuous minerals. An economically important structural feature of the deposit is a banding of minerals coinciding with the dip and strike of the dike. This is more pronounced in the footwall of the northeastern part of the intrusive, where there is also a higher than average concentration of ilmenite. According to Watson,' the TiO2 content of the Nelsonites of this region ranges from 10 to 42 per cent, while P205 varies from 4 to 15 per cent. It is inexpedient at present to disclose exact metal content of the Piney River ore body; suffice it to say that the average tenor lies well within the extremes noted by Watson. Sampling Methods and Procedure During a preliminary inspection of the ore body, Longyear engineers surmised that because of its soft, clayey character, drill sampling would yield little core, therefore they made all possible preparations to procure accurate samples of the drill cuttings, or sludge. The first requisite in obtaining representative drill cuttings is to secure their full recovery. Only under certain conditions, and by employing a most careful and rigid sampling technique, is this pos sible. There must be no loss of the water circulating in the hole, and the velocity

Jan 1, 1949

By D. J. Carney, E. Richard Randolph, E. Van Meter, J. J. Oravec, Stanley H. Ward, Gerald J. Anderson, Rolland L. 203-000-000-005 Blake

DURING the last 30 years the inductive electromagnetic method has been used chiefly in the search for massive sulphide mineralization. This application has met with varying degrees of success and in recent years has resulted in discovery of several large orebodies. Little has been written concerning its use in exploration for soft iron ores, but one of the present authors has reported on experiments with massive magnetic deposits.' To augment the exploration tools available to geologists in delineating iron orebodies, Cleveland-Cliffs Iron Co. and McPhar Geophysics Ltd. undertook in 1953 to apply the inductive electromagnetic method to Cleveland-Cliffs properties in the Lake Superior region. As a result of this project, equipment has been developed that enables simultaneous transmission of two audio frequency waves, and the field technique and interpretative procedure involved have furthered exploration in the district significantly. Thus far, inductive electromagnetic application in the Lake Superior region has been only a development tool, that is, it is used to locate obscured contacts and faults as a part of property expansion and development. However, its application to primary reconnaissance of unexplored areas may be feasible in the future. The method has assisted in placing drillholes efficiently, and the elimination of excess drilling foot-ages and/or actual elimination of unnecessary holes has amply justified the expense of the geophysical survey. Cost of the field work involved is comparable on a per station basis to the cost of a magnetometer or superdip survey. Since observations require no reduction, i.e., are directly interpretable, overall expenditure is low, and the scope and detail of the survey can be adjusted in the field as geological- geophysical correlation becomes evident. To a great extent, this eliminates the second-guessing so commonly arising after office calculations are completed on data obtained with other types of geophysical surveys. This unique feature of field interpretation and its associated intimate feel of the project area, is, perhaps, one of the most valuable aspects of the inductive electromagnetic method as applied to iron ore exploration. Basis of Method Fundamentally, the method involves transmission of an alternating electromagnetic wave, of a chosen audio frequency, which permeates the ground materials in the vicinity of a transmitting, or primary, coil, see Fig. 1. This wave, or field, induces an electric current in any conductor on which it is incident. The flow of an alternating current in a conductor sets up its own, or secondary, radiating electromagnetic field. These two fields form a resultant whose configuration depends on the following characteristics of the subsurface conductors: 1) size, 2) shape, 3) electrical conductivity, 4) magnetic permeability, and 5) frequency of the transmitted wave. To a lesser extent the resultant is also dependent on material adjacent to the conductor, topography, and surface conductivity. For illustrative purposes, the primary, secondary, and resultant fields may be represented by vectors. In operation, the direction of the resultant vector is measured by a small receiving coil tuned to the frequency of the transmitted wave. Generally speaking, the method can be compared to the transmission and reception of the familiar radio broadcast, with special variations permitting measurement of the effect on reception of intervening materials. Field Technique Mechanics of field operation are simple. The mast is set up in a vertical position and is then guyed in place. The transmitting loop then is raised by means of a sheave at the top of the mast and the coil connected to the motor-generator. A special plane table is clamped into position on the mast and the loop is plumbed. The plane table is oriented according to a grid system established over the project area. By means of this plane table it is possible

Jan 1, 1956

By R. A. Meussner, R. J. Goode

Six intermediate phases occur in the Nb-Zn sysThese phases form by peritectic reactions at 1120°, spectively. The Nb Zn 15 phase appears as the minor phase in the eutectic structure, and the terminal phases remain nearly pure niobium and zinc even at high temperature. Vapor -pressure measurements on the four high-temperature phases (Nb Zn to Nb Zn 3) permitted estimates of the composition limits of these phases and the calculation of approximate values of AFO, AH°, and AS°. 1 HE present study of the constitution of the binary Nb-Zn system was a part of an analysis of the mechanism by which coatings of the Nb-Zn intermediate phases protect niobium against oxidation at high temperature.' Since the primary interest in these phases was in coating service, attention in this study was given principally to the four phases stable at high temperature with only cursory attention to the two low-temperature phases. The solubility studies of niobium in zinc by Martin, Knighton, and Feder2 and the reports from the present study of the Nb-Zn coating represent the only published data pertaining to this system. Previously Hodge, Evans, and Hoskins, in an experimental survey, had noted that niobium was not resistant to attack by molten zinc, but no further observations were reported. EXPERIMENTAL PROCEDURES a) General. The nature of the binary Nb-Zn system precluded the use of more conventional methods of determining the phase equilibria such as thermal analyses of a series of cast alloys. An extrapolation of the liquidus data of Martin, Knighton, and Feder2 to higher temperatures suggested that the solubility of niobium in zinc would remain low in the entire temperature range of interest. The preliminary results of the present studies showed that all of the high-temperature intermediate phases form by peritectic reactions. Thus the sluggish nature of this type of reaction and the steepness of the liquidus indicated that thermal analyses would not yield reliable data. The peritectic reactions, of course, precluded the direct formation of samples of the individual phases from the melt. b) Materials. The niobium and zinc used in the present studies were of high purity. The niobium, in the form of 0.1-in.-diameter rods, contained 30 ppm 0, 30 ppm N, and 15 ppm C. Aside from 0.05 pct Ta, the metallic impurities (iron, titanium,

Jan 1, 1965

By Adrian M. Crawford

INTRODUCTION A study has been made of the stability of blocks and wedges of rock subjected to gravity forces in the roofs of underground excavations. Rock wedges may become wholly or partly self supporting with the mobilization of shear resistance of discontinuities bounding such wedges. The influence of in-situ stresses and the relative stiffnesses of the intact rock, and shear and normal stiffnesses of the discontinuities has been investigated. A two dimensional, plane strain model of symmetric rock wegdes in a horizontal stress field has been utilized. A comparison between the results of an extension of a closed form solution proposed by Bray(1981), and numerical analyses with Displacement Discontinuity elements (Crouch, 1976), are presented. These analyses indicate that the stability of the wedge and the stress redistribution around the wedge upon excavation of an opening is markedly influenced by the ratio of intact rock stiffness to seam normal and shear stiffness. It is shown that the analytical solution provides a reasonable measure of the lower and upper bounds of the loads necessary to cause failure of the wedge. MODELS The problem considered (Fig. 1) is a two dimensional plane strain model containing two discontinuities. The discontinuities are symmetrically disposed with respect to a horizontal excavation which forms a wedge of rock bounded by these discontinuities. The angle of the intersecting discontinuities at the apex of the wedge is 2[a]. Mechanical properties of the two discontinuities are identical, being represented by linear normal and shear joint stiffnesses Kn and Ks and angle of friction [o]. The rock wedge is loaded by an in-situ horizontal stress field [ah]

Jan 1, 1982

By C. R. Criss, R. J. McCormick

ThiS paper .summarizes the development and perform. ance of the Coldwater Oil field, Isabella County, Mich. Production is obtained at a depth of 3750 ft from a dolomite reservoir, which is probably both Rogers City and Dundee. There appears to be no persistent barrier to vertical fluid movement between the Rogers City and Dundee, and both formations are believed to have a common original oil-water contact. No we1ls are open to production at the level of the Dundee. The discovery of the field in 1944 was followed by the drilling of 81 producing wells and nine dry holes. By the end of 1952, the field had produced 12,763,000 bbl of oil, at which time 69 active wells were producing 3600 B/D oil and 21,000 B/D water. The reservoir has an effective natural water drive, and bottom-hole pressure has declined 75 psi from an original pressure of 1453 psi. Oil is undersaturated at reservoir conditions with a solution GOR of 512 cu ft/bbl and a saturation pressure of 1190 psi. INTRODUCTION Although the Coldwater Field is now in its ninth year of production, it ranks seventh in cumulative recovery, and second in current daily oil production in the State. Following complete development of the field in 1946, it has consistently contributed approximately 11 per cent of Michigan's daily production. Coldwater appears to have a greater pay thickness than most fields producing from the Rogers City forma- tion in the west central part of the Michigan basin. Except as influenced by the extent of closure and the thickness of the oil column, reservoir performance is believed to be representative of Rogers City fields in this part of the basin. For this reason, it is felt that the following presentation of factual data for the field will be of general interest. HISTORY AND DEVELOPMENT Discovery of the Coldwater field during Aug., 1944, followed favorable subsurface geological correlations and core tests drilled to a shallow stratigraphic marker horizon. The field is located in the west central part of the Michigan Basin in Coldwater Township (T16N-R6W), Isabella County. It is 60 miles west-northwest of Bay City, and near the geographic center of the southern peninsula of Michigan. The discovery well flowed 200 bbl of oil the first 24 hours from the Rogers City dolomite at a depth of approximately 3750 ft. Field production is principally from the Rogers City with a minor amount assumed to come from the underlying Dundee dolomite, although none of the wells are open to production at the level of the Dundee. Both the Rogers City and Dundee formations belong to the Devonian system (See Geologic Column-Fig. I.) In addition to Rogers City-Dundee oil production, sweet gas is produced from the Michigan Stray sand of the Mississippian system at a depth of 1400 ft. The gas reservoir has approximately the same areal extent as the underlying oil reservoir. Although gas production is an important feature of the Coldwater field, this report is concerned only with the oil reservoir. The productive area is approximately 3200 acres. The pool is developed on a 40 acre spacing pattern with wells drilled in the center of the north half of 40 acre tracts, except for a few off-pattern wells drilled along

Jan 1, 1955

By E. E. Brownson

THIS paper will be confined to the treatment of methods as applied in the laboratory of the Boston and Montana Reduction Department of the Anaconda Copper Mining Co. at Great Falls, Mont. As the electrolytic plant of this company operates at a current density of approximately 35 to 40 amperes per square foot when running up to capacity, the arsenic and antimony content of the anodes delivered to the, plant is of considerable importance as bearing on the purity of the refined cathodes turned out. Owing to the rather high relative percentage of antimony, it has always been the custom to determine antimony as well as arsenic in all forms of copper. Thus, anodes have been analyzed in which the antimony was about equal to the arsenic although the average shows about 2 parts of arsenic to 1 of antimony. In the refined copper the relative proportions of the two impurities vary considerably, but probably in the average are about equal. In this latter case, the percentage of the two is so small that ordinarily no attempt is made to separate them, the report of analysis showing percentage of As and Sb combined. Although rapid and exceedingly accurate determinations of arsenic may be made by means of various distillation schemes, the determination of antimony, either by itself or together with arsenic, has always been more or less cumbersome and has required a considerable amount of time. By the methods, details of which follow, the determination of arsenic and antimony, either separated as in the case of anodes or together in case of refined copper, is accomplished in 24 hr. from the time the sample is received by the chemist.

Jan 8, 1913