Search Documents

By Lawrence K. Jetter, Robert F. Mehl

SOME advances have been made recently in the theory of the kinetics of precipitation from metallic solid solution despite the complexities of the problem, but there is surprisingly little quantitative information available on rates of precipitation with which to test present theory or upon which to build new theory.? Attempts to measure rates of precipitation have been beset with difficulties which originate both in the anomalies that attend the changes in the properties selected for measurement, as, for example, in electrical conductivity or mechanical properties, and also in the complexities in the structural changes in some systems, as in the aluminum-copper system. If the functional relationship between the quantity of precipitate and the value of the selected property is uncertain, measurements of that property are obviously of uncertain utility in determining absolute rates of precipitation. If the precipitating system passes through one or more transition stages, the interpretation of measured rates lacks definiteness; in such cases, it is necessary to measure the rate of reaction in each separate stage, if the rate measurements are to have any significance from the kinetic point of view.* These difficulties cannot be wholly avoided, for at least in some measure they are characteristic of the process of precipitation from solid solution, but they can be minimized both by the selection of a simple system and by the use of a method of measurement relatively free from anomalous behavior. The present paper reports dilatometric measurements on the rate of precipitation of silicon from the aluminum-rich solid solution in the aluminum-silicon system-a study that approaches the desiderata of simplicity. The aluminum-silicon system offers advantages from these points of view: there are no known anomalies in the property changes accompanying precipitation ;2,3,4 there are no known transition stages; the precipitate is an element, not a compound, and both matrix and precipitate are cubic, and while the structures are not identical (the solid solution is face-centered cubic and the precipitate is diamond cubic), the system at least approaches the ideal case of a crystal precipitating from a matrix of the same crystal type-the ideal case which Becker5 assumed in treating the precipitation process theoretically. The dilatometric method, while not free from disturbing effects, as the subsequent dis-

Jan 1, 1942

By Thomas J. O’Neil

During the past five years, the mining industry has been subjected to new operating constraints that are unprecedented in number, scope, and urgency. The industry must operate in a safer, cleaner manner, yet produce more without large price increases. Compliance with any new sweeping legislation is always difficult-and particularly so in today's adverse economic climate, which is being aggravated by the steady stream of environmental control and tax-reform programs. In effect, while government is unwittingly but surely undercutting the country's productive capabilities, it blames industry for the resulting failure to meet consumer demand. Any such real or alleged failure then brings heightened bitterness from Congress. During the recent energy shortage, for instance, threats of nationalization were ventilated in public along with proposals to abolish the mineral depletion allowance.

Jan 11, 1974

By Dae S. Young

A new probabilistic approach is introduced for slope stability analysis including adverse impact of blasting vibrations. The material strength within a slope area is randomized in this bi-variate joint probability analysis. To be a completely general engineering method, the new probabilistic approach employs the random variable transformation technique: the Hermite model of the Gaussian transformation function, which transforms the experimental histogram of strength values to the standard Gaussian variables. Because bi- normal joint probability is analyzed on the true probability region projected on the Gaussian transformed variable plane, it is an exact solution of slope stability based on the available sample data. Details of the probabilistic approach are given through a case study on an iron ore mine. The case study demonstrated that the probabilistic approach is effective and simple enough to be a routine engineering practice for slope analysis.

Jan 1, 1984

By Henning Nielsen

SIX weeks ahead of schedule, the International Nickel Co. of Canada Ltd. has brought a 30-mile rail line into the newly born town of Thompson, Manitoba. Its construction spurs the development of a rich new mining region slated to become the world's second largest nickel-producing area-exceeded only by Inco's Sudbury, Ont., workings. Two mines, the Thompson and the Moak Lake, will be opened to meet International Nickel's scheduled annual production goal of 385 million lb of refined nickel by 1961. Accomplishment of this aim will mean an additional 75 million lb of the metal available to consumers. In addition, stepped-up out- put of Inco's Sudbury holdings may increase this figure by another 25 million lb. (For an earlier report on these developments see MINING ENGINEERING News, January 1957).

Jan 12, 1957

By Carl L. Renzoni

INTRODUCTION This paper defines equity as the issuance of a permanent interest in the business on a broadly distributed basis. As such, it excludes the issuance of equity to either a merchant bank or to another corporation. Nearly twenty years ago the equity markets were very simple: The instruments used were primarily common shares, convertible debentures or convertible preferred shares. Another equity-type option often used, especially by junior companies, was the sale of joint venture interests. Issue sizes were generally in the order of $25 - $100 million and issues were syndicated primarily in North America and Europe by one or two investment dealers. Mining corporations today benefit from a market with much more depth. Issues are syndicated by dealers on a truly international basis, and issue sizes now often range up to $300 million. Moreover, dealers are now willing to take significant risk in buying the issues for redistribution. This discussion of trends in equity markets will encompass: 1) common shares 2) warrants to buy common shares 3) convertible debentures 4) commodity backed instruments A review follows of events that affect the mining industry and investment dealers as they have a bearing on the equity markets for the metal producers. FACTORS AFFECTING THE MINING INDUSTRY The current business cycle, up to October 1987, had been characterised by a buoyant stock market and depressed base metal prices. Mining companies entered this period with weak balance sheets and little prospect of cash flows meeting capital needs. The issuance of equity and the sale of assets were used extensively to reduce debt to manageable levels. During this period, the relative high price for gold, and more important, the very high earnings and cash flow multiples afforded to gold producers, caused companies to target gold as the only game in town. The need for capital to acquire and develop gold properties prompted an unprecedented volume of equity issues. (Burns Fry led or co-managed over $1 billion of mining equity issues per year during this period). This high demand for equity capital by the industry prompted an increase in the use of equity instruments, such as commodity backed instruments. In addition, government tax incentive programs in Canada, such as flow-through shares, allowed smaller companies to raise significantly more equity than would otherwise have been possible. Over $1 billion in flow-through equity was raised in 1987 alone. The abundance of flow-through capital in Canada made it easy to form a new company. One flow-through share fund developed a system of providing the working capital required for a company to be eligible to receive flow-through share capital so that an entrepreneur required only a mining property to get started. Many new companies were formed and several flourished in a buoyant stock market environment to the point that market capitalizations grew to $100 million or more. The current period is in stark contrast to that before October 1987. The equity markets are generally available to the resource industry only on a window basis and only for senior companies and for special situations. The industry is benefitting from buoyant metal prices, and bankers are anxious to provide debt capital. Investment dealers previously processing several equity issues

Jan 1, 1990

By J. M. Locke

BRÜCKNER's revolving cylinders for roasting ores, etc., are now used at a number of the mills in Colorado and New Mexico, for the purpose of roasting and chloridizing silver ores, with highly satisfactory results, even from those cylinders of small size, erected before the many improvements of recent date. As examples of the larger improved cylinders, reference can be made to those erected at the Tennessee Reduction Works, Silver City, Grant County, New Mexico, and those which were built, in 1871, at the celebrated Caribou Silver Mill and Mines, Colorado, a mining enterprise which has proved so satisfactory as to have been lately sold to a Holland company for an enormous amount. These cylinders, as now constructed by Messrs. Lane & Bodley, of Cincinnati,, Ohio, are shown in Plate III, in which Fig. 1 is an elevation in perspective, Fig. 2 a longitudinal, and Fig. 3 a trans¬verse section. Fig. 4 is a sketch of a mill, with Brückner's cylinder. The exterior of the cylinder is a shell of boiler iron, 12 feet long by 5 feet 6 inches in diameter. The ends are partially closed with similar material, leaving in the centre a circular opening about 2 feet in diameter, bounded by a flange projecting several inches.. Upon one side is placed an opening closed by a hinged door. Upon the outside of the cylinder are bolted three bands, as shown in Fig. 1, in which the section of the first is square, and that of the third semi¬circular; the second, or middle band, is a strong spur gear. Passing through the cylinder are six pipes parallel to one another, in a plane at an angle of 15° to the axis of the cylinder; these pipes also lie in this plane at an angle of from 30° to 35° to the longitudinal, axis of the plane, as shown in Fig. 2, where the internal arrangement of the cylinder is seen, a perforated diaphragm being formed through part of the cylinder by means of perforated plates placed between

Jan 1, 1874

By C. A. Heiland

WITH seventeen papers submitted. and thirteen presented in three sessions, the geophysicists had a most successful meeting at New York in February. The first paper on Monday morning dealt with the location of a diabase dike near Chapel Hill, N. C., by magnetic and resistivity methods. The magnetic indications were pronounced directly over the dike. whereas the anomalies of apparent resistivity were less distinct and displaced away from the dike. In the second paper, Professor Keys reported on the results obtained with four different methods of depth calculation on known portions of the Falconbridge

Jan 1, 1937

By Samuel Lasky

WITH the movement of American capital into foreign investment, a new field of specialization for the American mining engineer is gradually opening a field hitherto entered almost wholly by chance and without full appreciation of its possibilities. Our age has been fitly called the "Age of Specialization." The special application of one's knowledge and ability to a definite and restricted branch of .his profession is purely a modern condition. Any profession, or branch of a profession or, industry, in which the problems may be segregated into definite types, calls for specializa-tion. Modern industry demands efficiency and that, reduction and ultimate annihilation of waste. Effort and time wasted by workers' on a problem with which they are not familiar is as flagrant a waste of money -the final standard-as any waste of materials. One of the subdivisions of mining engineering which is beginning to be recognized is of engineers who are clearly conversant with the particular and peculiar problems obtaining under foreign operating conditions. The need is as yet obscured, however, by the domestic prosperity of our American mining industry. The opportunity here lies more with the American engineer than with other nationals. The foreign en-gineer now in that service is not there through a realiza-tion of the special opportunities that exist, but through necessity, whereas, with the American engineer, more especially ,the recent graduate or those who will soon graduate, this is a new field to be entered wholly by choice. As a matter of fact, many engineering students will find it necessary to seek foreign service if they wish to remain in mining. Although the scope of the domes-tic industry is tremendous and there are many positions open to the junior engineer, there are not enough for the great number of graduates turned out yearly from our, mining schools. Educators tell us that less than 40 per cent. of the students in engineering schools gradu-ate; and of these but a minority continue in engineering. Even this minority is too great for our domestic. In-dustry, and although the young engineer realizes that condition after a few years he rarely seeks foreign work. A. perusal of the directory of the American Institute of Mining Engineers indicates that, but about one-half of one per cent of the Junior Associates are in positions outside of North America. Granting that most of them are still in school, the figure is surpris-ingly small.

Jan 1, 1927

By L. T. Leyson, U. C. Tainton

Some time ago, at ameeting of the Institute Prof. J. W. Richards1 said, "I take exception to the statement that all the factors in the production of electrolytic zinc were known long ago.... There is possible in my opinion an improvement of perhaps 50 per cent. in the new electrolytic processes." An examination of the literature of the subject will show the justness of Professor Richards' contention. The work of the earlier investigators was carried on in the shadow of difficulties that, today, are hardly more than memories. We seldom hear now of zinc sponge, that bête noir of the electrolytic-zinc pioneers. Zinc sponge was the name given to a peculiar, soft, black, non-adherent form of zinc deposit that was utterly useless for melting into ingot form. At the big plant at Cockle Creek, New South Wales, in 1897, Edgar Ashcroft2 said that the solution in the plant would suddenly, and without ascertainable cause, go' "bad" and begin to deposit spongy zinc. The most delicate, even spectroscopic, methods of analysis were unable to detect any difference between "good" solution and "bad" solution; either form might change to the other on being kept for a while. When it is added that an outbreak of this insidious disease (which appeared to be infectious, or at least contagious) could be dealt with only by discarding the solution and washing out all tanks and pipe lines, some idea may be gathered of the troubles of the zinc electrometallurgist in what may be spoken of as the "sponge age" of electrolytic zinc. Thanks to the efforts of a number of investigators, we are today able to diagnose with considerable certitude the nature of the malady that puzzled Ashcroft and his co-workers. The researches of Mylius and

Jan 1, 1924

By Robert J. White

Strong's equation for calculating bottom-hole pressure reduction due to gas cutting of drilling mud is corrected, resulting in a simpler equation which is easier to use. Use of the equation is illustrated by examples. It is shown that reduction of weight of a 10 lb/gal mud by 50 per cent at the surface due to gas cutting produces only n 3 per cent decrease in hydrostatic head at the bottom of a 5,000-ft well. It is also shown that at the surface 5 volumes of air per volume of mud are required to reduce the apparent mud weight from 8.5 to 6.5 lh/gal in a 3,000-ft well. Illustrative graphs are included to show the effect of various degrees of gas cutting on apparent mud weight at depths of 2,000, .5,000 and 10,000 ft and to show variation of apparent mud weight, with depth for a 100 lb/cu ft (13.37 lb/gal) mud gas cut to 90 lb/cu ft (12.03 lb/gal) at the surface. INTRODUCTION In 1938, Strong' published the following equation for calculating reduction in bottom-hole pressure due to gas cutting of drilling mud h = 1/D [p + pn/100 In p + p(1-n/100)/p(1- n-100)] where: h = depth in feet P = pressure in atmospheres at depth h due to mud column only D = hydrostatic pressure in atmospheres of a col-umn of uncut mud 1 ft high p = back pressure at well-head (in atmospheres) n/100 = fraction by volume of gas in mud at well-head at back pres-sure p This equation was recently found to contain an error due to an incor-rect expression for variation of vol-ume fraction of gas with pressure. Values calculated by the original equation are close to the correct values for small percentages of gas for which it was derived but become increasingly erroneous as the gas content increases and are completely unusable at the very high gas con-tents employed in aerated mud. DERIVATION The nomenclature used is the same as in Strong's paper. The pres-sure dP exerted by a lamina of thickness dh at a depth h ft is ex-pressed by Eq. 1 where x = volume fraction of gas at depth h dP = D (l - x)dh . . . (1) When we express x in terms of the wellhead per cent gas n, the well-head pressure p and the pressure P at depth h, the result is Eq. 2. x = (np/p+p)/(100-n) + (np/P + p) When this is substituted in Eq. 1 and rearranged to separate the var-iables the result is dh = 1/D [dp + np/100-n dp/(P + p]. Integration between appropriate lim-its results in or if the wellhead is open so that p = 1 atm and we rearrange Eq. 4, the result is loss in head = hD — P = n/100-n In (P + 1) ...(5) Eq. 5 can be solved easily by successive approximation using hD as a first approximation for P on the right-hand side and calculating a first value for loss in head. This can then be used to get a new value of P using the left-hand side of the equation. Values converge very rap-idly even for quite large values of per cent by volume gas n. EXAMPLES The effect on bottom-hole pressure of 50 per cent gas cutting of the mud in a 5,000-ft well using 10 Ib/ gal mud will be calculated, we have: h = 5,000 ft 10 X 7.48 144 X 14.7 = 0.0353 atm/ft hD = 176.5 atm n = 50 Substituting these values in Eq. 5 and using hD as a first approxima-tion of P on the right, we have, approximate loss in head = 50/50 In (176.5 + 1) = 2.30 log 177.5 = 5.17 atm. We calculate a new value of P as follows:

Jan 1, 1958

By L. C. Kern

This paper presents information on the use of a new propping agent (malleable aluminum particles) which has been used successfully for producing high-conductivity fractures. The conductivity of a packed fracture depends on the width of the fracture as well as the permeability of the propping material. It is significant that the flow capacity of a propped crack is often increased many fold by propping the crack with a sparse distribution of particles. However, the flow capacity of a sparsely propped crack can be limited by two phenomena: (I) crushing of the propping particles, and (2) embedment of the propping particles in the formation walls. Malleable aluminum particles exhibit interesting properties which tend to overcome these limitations. As high loads are applied to the particles they will deform slightly, rather than shattering. The deformation results in a greater bearing area against the formation wall. This reduces the stress on the particle and reduces particle penetration into the formation. The behavior of aluminum particles under load and the bearing capacities of serveral formation rocks have been measured in the laboratory. By properly using these data, as explained in this paper, the flow capacities of aluminum-propped cracks can be calculated for a variety of conditions. Aluminum particles have been used successfully in the field to prop fractures. Where high-conductivity fractures were needed, the aluminum-propped fractures have given greater well stimulation than could have been expected for conventional fracturing processes. INTRODUCTION The purpose of a hydraulic fracture treatment is to create a conductive channel from the wellbore out into the oil or gas formation. The word conductive is emphasized because we believe that the fracture conductivity (flow capacity) is one of the most important factors influencing fracturing results. Previous papers have pointed out the additional well stimulation that can sometimes be achieved by increasing fracture conductivity. Several years ago, we investigated in some detail the effect of fracture conductivity on productivity increases to be expeced from vertical fractures. Both electrical analog and theoretical studies of unsteady-state flow behavior were made. A discussion of the electrical analog equipment and some of the results of the study were given in a previous paper' by Dyes, Kemp and Caudle. Further details were given recently by McGuire and Sikora.5 Fig. 1 shows the remarkable influence of relative fracture flow capacity and length on well stimulation. Briefly, the study indicates the following. 1. High-permeability formations require high-conductivity cracks for best results. 2. The longer the crack, the higher the fracture conductivity required for best results. 3. If the conductivity of the crack is very large compared to the formation (i.e., flow is not being limited by crack conductivity), then the longer the fracture, the better will be the results. Judging from recently published articles,1,314 there is current interest in methods for obtaining high fracture conductivities. Hence, we would like to present in this paper a discussion of a new fracture propping process (use of aluminum particle) which we have used successfully to obtain highly conductive fractures. There are several factors which influence the conductivity of a propped crack. Conventional fracturing techniques frequently result in a crack completely packed with fracturing sand. For such conditions, the crack conductivity is the product of the width of the packed fracture and the permeability of the propping material. It is significant that a large increase in conductivity sometimes can be obtained by propping with particles which are distributed sparsely (less than a

By Philip M. McKenna

WHEN a new material becomes available to industry, it is useful to describe its properties as a guide to its most effective application; and when the new material may be produced in compositions having a series of graded properties, tests to select the combination of properties best adapted for various uses are helpful. The class of materials to be considered in this paper are hard tool materials produced by processes of powder metallurgy from hard carbide constituents and various matrices of iron, nickel or cobalt, or alloys of them with tungsten, or tungsten and carbon. The customary use of carbide hard alloys is for metal-cutting tools; although wire-drawing dies, lathe centers, follow rests, grinding rests, burnishers, rolls, extrusion dies, measuring gauges and micrometers, and a number of other tools are also made with these hard alloys as the essential wear-resisting parts. The properties and tests to be considered are those affecting these uses. In the development of tool materials since the industrial revolution we have had carbon tool steels, Mushet steel, high-speed steels, stellites, and now cemented carbide compositions. For an understanding of the latter category of materials their properties and uses relative to the older and more familiar tool materials will be considered. Hardness has been the property of greatest practical interest in tool materials. The word "hardness" is a generalized term lacking definite¬ness unless the specific test used is described. However, efforts to explain physical properties as a consequence of chemical bond, and distance between atoms in chemical compounds have been illuminating. This seems the most generalized attack on the problem, and is based upon the idea that atoms in a lattice are held together as the square of the valence and inversely as the square of the distance between the atoms. The compounds compared must all be of the same crystalline arrangement. It is interesting to note the values of the figure [V ] a number of

Jan 1, 1938

By C. G. Dunn

It is well known that plastic deformation alters many of the properties of a metal and subsequent heat-treatment partially or completely restores these properties.l In the deformed or strained state, the metal is unstable and tends to change toward a condition called a "strain-free state." The transformation occurs through recovery, recrystallization, and grain growth—processes that may take place singly or in combination. The distortion of the lattice of an individual grain of a metal in a state of strain may be rather complex in nature, because plastic deformation produces: (I) dislocations within mosaic blocks; (2) elastic variations of the lattice spacings; and (3) gross alterations throughout the lattice, especially along slip planes, along composition planes between a grain and its mechanical twins, and along boundaries of deformation bands. These gross alterations are of the nature of bent planes or rotated regions of the crystal lattice and are revealed by a spread in the orientation of the grain. Although we cannot describe these strains and their formation accurately because of insuffcient knowledge, we can, nevertheless, use the information as well as possible to obtain a better understanding of recovery processes. In recovery, the lattice of a grain is not made anew as it is in recrystallization, but is improved or mended in such a way that the basic structure remains unaltered: Until recatly observations were .that recovery produced no marked changes in the shapes of spots in Laue diffraction patterns, whereas recrystallization did, but now it is known for silicon ferrite2 that Laue spots may become quite sharp entirely through recovery. Consequently, the shape of Laue spots alone would not be a suitable test to distinguish between recovery and recrystallization. There is considerable evidence that the micro-structure usually does not change visibly during recovery. Absence of a visible change in the microstructure, therefore, provides a sufficient test of recovery in many cases. However, including this observation in a definition of recovery as a necessary condition (this is usually done) is unfortunate, because recovery may, as will become evident later, produce new grain boundaries that are visible not only in the microstructure but also in the macrostructure. For the present, therefore, let us say that a necessary condition for a process to be one of recovery is that the principal orientation or orientations of a deformed grain be essentially unchanged throughout the transformation toward the strain-free state. Several transformations may occur that fulfill this condition, and the nature of the distortion in a grain indicates what these must be if the lattice is to be mended in part or fully. Consequently, it will be convenient as well as

Jan 1, 1947

By C. G. Dunn

It is well known that plastic deformation alters many of the properties of a metal and subsequent heat-treatment partially or completely restores these properties.l In the deformed or strained state, the metal is unstable and tends to change toward a condition called a "strain-free state." The transformation occurs through recovery, recrystallization, and grain growth—processes that may take place singly or in combination. The distortion of the lattice of an individual grain of a metal in a state of strain may be rather complex in nature, because plastic deformation produces: (I) dislocations within mosaic blocks; (2) elastic variations of the lattice spacings; and (3) gross alterations throughout the lattice, especially along slip planes, along composition planes between a grain and its mechanical twins, and along boundaries of deformation bands. These gross alterations are of the nature of bent planes or rotated regions of the crystal lattice and are revealed by a spread in the orientation of the grain. Although we cannot describe these strains and their formation accurately because of insuffcient knowledge, we can, nevertheless, use the information as well as possible to obtain a better understanding of recovery processes. In recovery, the lattice of a grain is not made anew as it is in recrystallization, but is improved or mended in such a way that the basic structure remains unaltered: Until recatly observations were .that recovery produced no marked changes in the shapes of spots in Laue diffraction patterns, whereas recrystallization did, but now it is known for silicon ferrite2 that Laue spots may become quite sharp entirely through recovery. Consequently, the shape of Laue spots alone would not be a suitable test to distinguish between recovery and recrystallization. There is considerable evidence that the micro-structure usually does not change visibly during recovery. Absence of a visible change in the microstructure, therefore, provides a sufficient test of recovery in many cases. However, including this observation in a definition of recovery as a necessary condition (this is usually done) is unfortunate, because recovery may, as will become evident later, produce new grain boundaries that are visible not only in the microstructure but also in the macrostructure. For the present, therefore, let us say that a necessary condition for a process to be one of recovery is that the principal orientation or orientations of a deformed grain be essentially unchanged throughout the transformation toward the strain-free state. Several transformations may occur that fulfill this condition, and the nature of the distortion in a grain indicates what these must be if the lattice is to be mended in part or fully. Consequently, it will be convenient as well as

Jan 1, 1947

The following is a list of members who died in 1928. It is compiled from reports to the Secretary's office. Biographical sketches published in Mining and Metallurgy are indicated in the last two columns. Issue Containing Year or Date or Biography Election Name Death 1928 Page 1914 Adams. David T.................... July 22 October 471 1905 Aguilera. Pedro................... May 3 October 469 1902 Althouse, H. W.................... NOV. 3 December 559 1920 Averill: C. C...................... July 9 October 471 1915 Baldwin, C. Kemble............... Aug. 9 October 471 1926 Barquist, Walter C............... NOV. 14 June 298 Barron,* Clarence Walker......... Oct. 2 November 511 1917 Beasley, Fred E.................... Aug. 31 October 471 1901 Belden, S. B....................... May 15 July 333 1927 Binney, Edwin, Jr.................. Dec. 29 February 96 1915 Bonsall, James Malcolm............ Feb. 12 June 284 1917 Boyle, John....................... July 12 December 561 1913 BradEn, Eugene B............. Jan. 29 March 157 1889 Bulkley, Frank.................... Mar. 25 May 240 1896 Callaghan, J. T., Jr............... Apr. 1 1892 Chalmers, George.................. Feb. 4 April 197 1898 Clark, Josiah H.................. May 7 July 333 1887 Copeland, F. K............. Nov. 10 December 561 1915 Cunningham, B. L11............... Dec. 6 August 294 1888 Dana, R. T........................ Aug. 20 December 559 1907 Dennis, Clifford G............... Dec. 28 March 1 1920 DeVenny, Thomas................ Feb. 13 April 197 1882 d'Invillier-, Edward V........... Jan. 4 March 157 1884 Duncan, M. M..................... Dec. 17 February 96 1924 Dyrssen, WaldemaR ............... Aug. 4 October 471 1906 Edmondson. H. W................ Dec. 21 February 1884 Emmerton, F. A.................. Oct. 9 June 298 1911 Eu, S. H............................ July 20 February 1917 Farrand, Ira W.................... Sept. 6 October 469 1900 Fell, E. Nelson...........•......... Mar. 25 May 231 1918 Fenton, Clarence M.............. October Junet 298 1908 Ferraris, Erminio................. Sept. 22 June 298 1914 Galloway. A. D. R............... December April 215 1924 Grant, A. W., Jr................... .4pr. 5 June 285 1917 Grant, Clifford G............... Jan. 26 January? 37 1918 Grant, Frank E.............. Jan. 14 September 417 1921 Gunderoth, C. J.................. Feb. 15 1897 Harms, Ernest..................... Aug. 12 November 512 1891 Hartrick, J. S..................... Feb. 9 June 285 1925 Hochschild, Berthold.............. Jan. 24 April 197 1917 Hutton, L. W...................... NOV. 3 January 37 1894 Jenning", S. J...................... NOV. 17 December 560 1925 Jones, J. Ravenscroft............... Jan. 29 March 157 1880 Jones, J. T......................... May 4 June 284

Jan 1, 1929

By J. R. Martson

The arrangement of the larger furnace at the United Verde smelter, together with the boiler layout and connecting flues, is shown in Fig. 1. The important dimensions are given in the figure, and cross-sectional areas of combustion space, flues, etc., are recorded. The location and extent of the baffling in the boilers also are shown because of their importance in the interpretation of the data. Two boilers serve each reverberatory furnace. They are of the class M-26 Stirling type (rated at 713 boiler hp. each). Steam is generated at 178-lb. gage pressure at a total temperature of 528" F., from feed water at a temperature of 113" F. The feed water is condensate from turbogenerators plus make-up softened by the lime-soda process. The make-up is rather large in amount as it must match the amount of steam consumed in reciprocating blowing engines and the like, which are not served by surface condensers. As a result the boiler feed water has a hardness of 1.5 to 3.0 grains per gallon, but this results in the formation, during six months to one year of boiler operation, of scale only of "eggshell " thickness or less. The boilers are set at the same elevation as the tapping floor of the furnace, which results in the introduction of the waste-heat gases at the top of the front bank of tubes and necessitates the inversion of the usual baffling arrangements. The boilers are equipped with valve-in-the-head soot blowers, which keep most of the dust blown off the surface of the tubes, but it is necessary to supplement the soot blowers by high-pressure air lances, inserted by an attendant through side doors in the boiler setting. Deposits of coal ash and of dust from the furnace charge accumulate in the flues between the reverberatory furnaces and the boilers and this necessitates cleaning of these connecting flues by hand during the greater part of one of the three 8-hr. shifts during each 24 hr. This cleaning operation requires the opening of clean-out doors, which, of course, has some effect on the yield of steam. Revebberatory Furnace Practice The United Verde furnaces are fired with pulverized coal of sub-bituminous type of which the screen and chemical analyses are given in Table 1.

Jan 1, 1934

By B. Chalmers, S. Wojciechowski

THE structure of the equiaxed zone of several A1-Cu samples mechanically stirred during unidirectional solidification was examined. The stirring was produced by rotary oscillation of the mold about its vertical axis.' It was found that in Some samples the structure is not of the same type over the whole of the equiaxed zone; it consists of regions with two different etching responses. Fig. 1 shows this structure in a Al-1 wt pct ku sample. The lighter etching regions with a coarse structure form something like a network and the darker etching regions with a finer structure can be observed as the continuation of the coarse structure inside this network. The difference in size and shape of the dendrite branches (they are rounded in the coarser structure) is similar to that found by Williamson and Chalmers in ice crystals solidified in undercooled water: when the amount of undercooling was small, the ice crystals were more rounded and coarser than these solidified with a larger amount of undercooling.' It seems justified to conclude that the observed structure resulted from solidification under different thermal conditions: the coarser structure solidified first out of the "purer" liquid and with a smaller amount of undercooling and the finer was formed later out of solute-enriched liquid under conditions of much more rapid heat extraction. A considerable change in the heat flow conditions at the later stages of solidification can be easily understood by taking into account that the coarser crystals form a continuous network and the amount of trapped liquid is relatively small; hence the contribution of latent heat is much smaller in the later stages of solidification. The difference in structure and etching characteristic reflects a difference in composition between these two regions. It was found that the darker etching re- gions are harder (30.4 to 31.3 HV5) than the lighter etching ones (25 to 26 HV5). A similar type of structure was found in a A1-4 wt pct Cu sample grown by Czochralski method. Fig. 2 shows the structure in the lower part of a sample grown slowly and then decanted by a rapid removing of the sample from the melt. In a few places trapped liquid solidified in the same manner as in the sample shown in Fig. 1.

Jan 1, 1968

By John J. Cioston

THE steadily rising flood of gold production from all parts of the world has created an avalanche of rumors regarding the stability of the present price of this metal. Markets have been unsettled from Johannesburg to London from New York and Toronto to Melbourne, despite repeated denials from, American and British authorities of any immediate intention to alter the price. Various economists and financial writers have blossomed forth with predictions that the price would be set at the old level of $20.67 per oz.; some have even been so brash as to state That a price of $15 would be necessary to bring production within control. These effusions, based entirely upon monetary theories and with no regard to production costs, serve to confuse rather than clarify the situation.

Jan 1, 1937

By Charles E. Weaver

During the past few years there has been considerable activity in prospecting for oil and gas in several parts of western washington. From time to time seepages of oil or emanations of gas have been reported from various places. Several companies have been organized for the purpose of drilling, but only a part of these have actually begun operations. In certain localities very small seepages of oil occur, but up to the present time no oil or gas in commercial quantities has been obtained. In order to determine the conditions which may be favorable or unfavorable to the occurrence of petroleum it becomes necessary to know the character and extent of the geological formations in which such deposits might occur. In other regions where producing wells have been developed it is possible to know what formations contain the oil and what structural conditions influence its concentration in reservoirs or zones. It is usually possible to determine those strata which contained the materials from which the petroleum may have been derived and also the position and distribution of the more porous sandstone belts into which it may have collected. Detailed stratigraphic surveys may even determine the depth at which a certain known oil-bearing zone may be tapped at any particular place. It is also possible to recognize those formations which are presumably barren of oil, as well as those which are absolutely so. In new regions far distant from any of those which are now producing or have produced in the past, it becomes absolutely impossible to foretell whether oil may exist in commercial quantities or not. Assuming that such deposits do exist, it is extremely difficult to predict at what depth the produciqg zone or zones occur. However, in prospecting in a new and unexplored region, use should be made of such laws as have been found to govern the occurrence of petroleum deposits in other well-developed fields. Such deposits in their world-wide distribution are found almost exclusively associated with sedimentary rocks. Areas composed predominatingly of igneous and metamorphosed rocks are to be rcgarded as extremely unfavorable localities for the occurrence of commercial deposits of oil or gas. Assuming that such oil deposits are

Jan 1, 1916

By S. Fróes Abreu

The importation of liquid fuels in Brazil amounts to about 1,300,000 tons; 30 per cent of this total being gasoline for automobiles and airplanes. Statistics show an increasing consumption of gasoline notwithstanding the use, daily greater, of fuel alcohol, a domestic fuel of low cost in the producing areas. The Brazilian market for petroleum products has shown a tendency to grow as the country has steadily developed— expansion of the industries in the areas already developed, and also the recent occupation and population of new zones. The war has brought many difficulties to Brazil. It has limited the importation of petroleum products, which came mostly from the United States, Venezuela and Mexico. During the first days of the present crisis automobile and truck traffic was vastly curtailed; but the national activity in the production of more fuel alcohol, and principally in the development of producer gas, has done much to provide a solution for the transportation crisis threatened at the beginning of the gasoline shortage. Many thousands of cars and trucks in Brazil are now burning producer gas made from charcoal. Producer gas for automobiles has been improved by Brazilian engineers and many new types have appeared. - Production There is only one producing oil field in Brazil—the one in the State of Baia, near the Baia de Todos os Santos. The first producing oil well was drilled in Lobato in 1939 by the Federal Government following studies carried on in that area by Oscar Cordeiro, S. Froes Abreu, G. Paiva and J. Amarai. The field and laboratory work done by these men was published in 1936 in a paper entitled " ContribuicBes para a Geologiado Petroleo no Reconcavo (Baia)," which indicated the potentialities of the area as an oil producer. After the discovery of the first producing well, the Brazilian Government issued a decree establishing an area, 60 km. in radius, as a National Reservation. This first well was drilled in Lobato. In no other locality in Brazil is any petroleum produced. Although many wells have been drilled in the southern part of Brazil, on the northeastern coast and in the Amazon Basin, they yield nothing. Actual production is below 1000 bbl. daily. The producing area covers Itaparica Island, Candeias and Arath, Joanes Island and Lobato. Since very little geological information was available, especially about subsurface structure, it was necessary to drill several wildcats in order to collect the data essential in the choosing of good locations. The United Geophysical Co. was contracted to perform a geophysical survey to clear up the major problems concerning the oil deposits in the Reconcavo beds. The best wells in Reconcavo are on Itaparica Island, where the daily flow amounts to about zoo bbl.; in other sectors production is considerably lower and most of the wells are pumping. In the Aratfi sector, near an area of very light oil, there is an important gas field, with wells producing about I0,000,000 cu. ft. daily.

Jan 1, 1944