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By H. C. Chang, N. J. Grant, A. R. Chaudhuri

During the creep of coarse-grained polycrystalline magnesium at elevated temperatures, a nonbasal type of slip was found to play an important role in the deformation processes. The nonbasal slip traces were examined metallographically in eight specimens (13 grains) and the observed glide plane located stereographically for each grain. The tests were run at 500&apos; and 700°F at stresses of 148 to 786 psi. Based on these measurements and theoretical calculations, the crystallographic elements for nonbasal slip were determined. WHEN a metal deforms by slip, the conventional appearance of the slip bands on the surface of a specimen is that of straight lines. Such is the behavior of the face-centered-cubic metals, as for example, aluminum. The particular slip system on which slip occurs in these metals is governed by the criterion of resolved shear stress. Work on the body-centered-cubic metals a-iron,&apos;. &apos; molybdenum, and columbium4 has shown that the process of slip is somewhat more complicated than the simple gliding of one close-packed plane of atoms over another in a close-packed direction and that it results in the formation of wavy and irregular slip traces on the surface. The recent reviews and experiments of Vogel and Brick and Chen and Mad-din3 show that, for the body-centered-cubic metals, the resolved shear stresses along the planes and the degree of close-packing do not necessarily determine the slip system. Theirs and other investigations indicate that a complete understanding of the slip process in the body-centered-cubic metals is not yet possible. However, one behavior displayed by all these metals is that the slip direction is invariably one of the close-packed directions <11l>. The wavy nature of the slip-band traces has been explained on the basis of cooperative slip by planes sharing this same slip direction.1&apos;3l&apos; It is generally acknowledged that, when the hexagonal-close-packed metal magnesium (axial ratio c/a = 1.624) deforms by slip at room temperature, it does so by basal slip in the close-packed direction <1I%>. This type of slip has the conventional appearance of straight lines and is governed by the critical shear-stress law. Schmid and coworkers" showed that basal slip was operative in the temperature range of —185" to 300°C (—300" to 572°F). Work by Servi, Norton, and Grant6 has shown that, during the creep of coarse-grained aluminum at high temperatures, new slip systems come into operation. The existence of a new high temperature slip system at temperatures greater than 225 °C (437°F) for magnesium was suggested also by Schmid. This was later indicated by Bakarian and Mathewson&apos; to be slip along the pyramidal planes (10i1) in the close-packed direction <11%>.* They * Mention will be made in the text of pyramidal planes and prismatic planes. The pyramidal planes referred to are the type I. order 1 of the form {10il); and the prismatic planes of the type 1 of the form (10i0). For the sake of brevity, they are termed in the teat as pyramidal (10il: and prismatic (10i0) planes, respectively. Where reference is made to the pyramidal plane type 1, order 2 of the form {10i2), they are referred to as the pyramidal planes of the type (10i2:. observed that this kind of slip resulted in irregular markings on the specimen surface. According to them, a possible cause for the appearance of the markings was due to "limited accessory slip on the pyramidal {10i2) planes." Burke and Hibbard," on deforming a single crystal of magnesium at room temperature, found evidence of slip on a pyramidal plane {1011). They explained it as being due to the effect of grip restraints. It is pertinent to note at this point that, although basal slip has received a fair amount of attention, only two specimens have been investigated, that of Bakarian and Mathewson and of Burke and Hibbard, to establish the elements of nonbasal slip in magnesium. During the study of the deformation mechanisms

Jan 1, 1956

By L. M. Pidgeon, P. G. Thornhill

A LTHOUGH a considerable number of experi--ti mental investigations dealing with the roasting of sulfide minerals have been reported in the past,&apos;"" the behavior of the single roasting particle does not appear to have received the attention it perhaps deserves. This is understandable in that the natural sulfide counterpart of the slab or sheet of metal normally used in high temperature oxidation studies is difficult to obtain and prepare, and is, in most cases, virtually impossible to maintain in one piece at roasting temperatures. The employment, on the other hand, of static aggregations of small particles in masses great enough to permit evaluation of the roasting reactions by means of thermobalances or gas analyses introduces other complications, such as localized overheating, sintering, and variable gas-solid contact. In this investigation a compromise between the above extremes was attempted. Closely sized (e.g., 30 to 40 mesh) particles of natural sulfide minerals were isothermally roasted, out of contact with one another, in an air-swept system. The progress of the roasting reactions was followed by examination in polished section of the treated particles and by X-ray and chemical analysis of their residual sulfide kernels. In this way some conclusions respecting the mechanism of roasting reactions were drawn. Roasting Furnace—The vertical tube furnace used for roasting the sulfide particles had a heated zone 10 1/2 in. long in which four retractable light gage stainless steel trays were suspended. Each tray, and an accompanying baffle, was mounted on a 2 in. lengtn of 3/8 in. stainless steel tubing. These assemblies were axially suspended on a 30 in. length of ¼ in. stainless tubing, by means of which they could be lifted from the hot zone to a water-cooled brass chamber at the top of the furnace. Since each tray unit could slide freely on the 30 in. tube, any desired number of the trays could be retained in the cooling chamber by the manipulation of a horizontal plunger during a momentary withdrawal of the four trays from the hot zone. Although three heating coils, each equipped with variable external resistance, were employed, it was found impossible to avoid a drop of 10o to 15oC between the temperature at the top tray and that of the lower three. Consequently, only the bottom three trays were used for roasting. Temperature readings inside the furnace were made by means of a thermocouple inserted down the tray support tube at tray levels, and a separate thermocouple, inserted adjacent to the middle heating coil, was connected to a Micromax temperature control unit. Experimental Method—The sulfide minerals were obtained in a form as free as possible from gangue and contaminating sulfides, and were crushed and screened to the required particle size range. The tray assembly was kept inside the furnace during the heating-up period and, when a steady temperature had been reached, the trays were withdrawn. Each tray was sprinkled with from 200 to 500 mg of the sulfide grains, and the assembly was lowered into the furnace without delay in order to minimize the time required to achieve the operating temperature. The furnace top was then clamped into position and the thermocouple inserted down the center tube to the required level. It was found that, when this procedure was used, the trays achieved their former temperature within 2 min, after which time the flow of dry air was begun at a rate of 1 liter per min, and timing of the run was started. At the required intervals of time the trays were successively withdrawn from the hot zone and stored in the cooling chamber by means of the retention plunger. On completion of the run the treated particles were removed from the trays to be set aside for examination. The roasted particles were mounted in Lucite on a Buehler press Operating at a temperature of 140°C

Jan 1, 1958

By J. H. Wernick, D. Dorsi, K. E. Benson

A LTHOUGH a considerable number of experi--ti mental investigations dealing with the roasting of sulfide minerals have been reported in the past,&apos;"" the behavior of the single roasting particle does not appear to have received the attention it perhaps deserves. This is understandable in that the natural sulfide counterpart of the slab or sheet of metal normally used in high temperature oxidation studies is difficult to obtain and prepare, and is, in most cases, virtually impossible to maintain in one piece at roasting temperatures. The employment, on the other hand, of static aggregations of small particles in masses great enough to permit evaluation of the roasting reactions by means of thermobalances or gas analyses introduces other complications, such as localized overheating, sintering, and variable gas-solid contact. In this investigation a compromise between the above extremes was attempted. Closely sized (e.g., 30 to 40 mesh) particles of natural sulfide minerals were isothermally roasted, out of contact with one another, in an air-swept system. The progress of the roasting reactions was followed by examination in polished section of the treated particles and by X-ray and chemical analysis of their residual sulfide kernels. In this way some conclusions respecting the mechanism of roasting reactions were drawn. Roasting Furnace—The vertical tube furnace used for roasting the sulfide particles had a heated zone 10 1/2 in. long in which four retractable light gage stainless steel trays were suspended. Each tray, and an accompanying baffle, was mounted on a 2 in. iength of 3/8 in. stainless steel tubing. These assemblies were axially suspended on a 30 in. length of in. stainless tubing, by means of which they could be lifted from the hot zone to a water-cooled brass chamber at the top of the furnace. Since each tray unit could slide freely on the 30 in. tube, any desired number of the trays could be retained in the cooling chamber by the manipulation of a horizontal plunger during a momentary withdrawal of the four trays from the hot zone. Although three heating coils, each equipped with variable external resistance, were employed, it was found impossible to avoid a drop of 10O to 15OC between the temperature at the top tray and that of the lower three. Consequently, only the bottom three trays were used for roasting. Temperature readings inside the furnace were made by means of a thermocouple inserted down the tray support tube at tray levels, and a separate thermocouple, inserted adjacent to the middle heating coil, was connected to a Micromax temperature control unit. Experimental Method—The sulfide minerals were obtained in a form as free as possible from gangue and contaminating sulfides, and were crushed and screened to the required particle size range. The tray assembly was kept inside the furnace during the heating-up period and, when a steady temperature had been reached, the trays were withdrawn. Each tray was sprinkled with from 200 to 500 mg of the sulfide grains, and the assembly was lowered into the furnace without delay in order to minimize the time required to achieve the operating temperature. The furnace top was then clamped into position and the thermocouple inserted down the center tube to the required level. It was found that, when this procedure was used, the trays achieved their former temperature within 2 min, after which time the flow of dry air was begun at a rate of 1 liter per min, and timing of the run was started. At the required intervals of time the trays were successively withdrawn from the hot zone and stored in the cooling chamber by means of the retention plunger. On completion of the run the treated particles were removed from the trays to be set aside for examination. The roasted particles were mounted in Lucite on a Buehler press operating at a temperature of 146°C

Jan 1, 1958

By Allen L. Hatch

A survey of all phases of the world&apos;s lead and zinc production in 1968 from ore through to refined metal was conducted by sending questionnaires to individual companies ad the results of this survey are tabulated at the end of the paper. The paper goes on to review changes in the geographical distribution of the world&apos;s lead and zinc mine and metal production and in the trading patterns of raw materials, present and future utilization of metal production capacity, developments in metal smelting and refining processes and the growing importance of marketing, product development and research in the 1950&apos;s and 1960&apos;s.

Jan 1, 1970

By Robert J. Hite, Samuel S. Adams

Potash, the generic term for a variety of potassium-bearing minerals, ores, and refined products (Table 1), owes its importance as an industrial mineral to the potassium requirement of growing plants. The term potash originally referred to potassium carbonate produced by the leaching of wood ashes. This process, for which the first US patent was issued in 1790, was the basis for the largest United States chemical industry in the early nineteenth century. The agricultural use of potash soon eclipsed the chemical applications following the German discovery in 1840 that potassium is essential to plant growth. The initial discoveries of large deposits of soluble potassium minerals, essential for agriculture applications, were made in 1857 in Germany and in 1914 in the United States. More than 90% of the 27.5 Mt K20 produced in the world in 1980 (Searls, 1981) was derived from marine evaporite deposits and approximately 90% was used in fertilizers. The potassium content of an ore, mineral, or product is customarily expressed as % K20, a unit of measure which is neither a natural nor synthetic compound of potassium (1.0% K is equivalent to 1.2046% K2O). Geology Potassium, the seventh most abundant element in the earth&apos;s crust, is present in silicate minerals in igneous, sedimentary and metamorphic rocks. Potassium is also a major constituent of many surface and subsurface brines (Table 2). Economic potash deposits are essentially restricted, however, to widespread, thick accumulations of marine chloride evaporite deposits. These deposits yield high grade, large tonnage ore bodies, many of which are amenable to low cost mining and beneficiation. The products from these deposits are, moreover, ideal for use in fertilizer because of the high relative solubility of the potassium chloride and sulfate evaporite minerals. World potash production and reserves for such deposits so vastly overshadow other sources of potassium that the following discussion will be limited largely to potash deposits in marine evaporites with brief reference to certain potash-rich brines. Approximately 85% of current domestic production is from bedded salt deposits and much of the balance is from brines. Marine evaporite deposits are accumulations of salt minerals deposited in structural sedimentary basins through the evaporation of seawater or mixtures of seawater and other brines. The salt minerals are precipitated in assemblages and sequences of assemblages as determined by the compositions of the brines and the solubility relations in the salt systems (D&apos;Ans, 1933). The evaporation of seawater normally yields carbonate minerals as the first precipitates (Table 3). Further evaporation and concentration of the brine leads to the precipitation, in succession, of sulfate, chloride, and supersaline mineral assemblages including the salts of potassium and magnesium. The common minerals, ores, and products of potassium deposits are listed in Table 1. Many potash deposits contain accessory evaporite minerals together with a variety of detrital and authigenic silicates (Braitsch, 1971). The structural basins within which marine evaporites occur are of two main types: (a) cratonic basins formed by broad epirogenic movements (for example, the Michigan Basin of the midwestern United States and the Permian Zechstein Basin of eastern Europe), and (b) grabens, commonly related to continental

Jan 1, 1983

By F. F. Aplan, D. W. Fuerstenau

This chapter presents modern concepts of the flotation of nonmetallic minerals. In particular, it is concerned with such minerals as metal oxides, silicates, sulfates, carbonates, and halides. It is not the purpose to duplicate the two excellent, recent treatises by Gaudin l and by Sutherland and ark,^ but rather to expand their correlations of data, particularly in view of recent, ex- citing new experiments which are shedding new light on the principles of non- metallic flotation. Outstanding success has been achieved over the past 50 years in separating one sulfide from another or from the gangue constituents using a minimal amount of reagents. In contrast to this, selective flotation in nonmetallic systems is often difficult in that one class of compounds alone, the carboxylic acids, may float nearly the entire array of nonmetallic minerals under the appropriate conditions. Moreover, while lime, cyanide, sodium sulfide, and copper sulfate constitute the principal modifiers used to obtain selectivity among the various sulfides, the nonmetallic mineral flotation engineer is con- fronted with a vast array of modifying reagents. In sulfide and native-metal flotation, a strong chemical adsorptive bond is generally formed between the mineral and sulfhydral collector. In fact, re- cent radio-tracer studies show that below monolayer coverage as much as 98% of added mercaptan is adsorbed on the surface of gold.? Contrasted to this, Bloecher&apos;s data indicate that for the quartz-amine system only about 60% of the collector is adsorbed.4 This greater residual concentration in the solution results from weaker forces of adsorption in the quartz-amine system. In the flotation of nonmetallic oxide minerals, collector adsorption results from rather weak physical forces, primarily electrostatic attraction and van der Waals attraction between hydrocarbon chains. In the flotation of salt-type minerals, carboxylic acids are adsorbed both by physical and chemical forces. It is a study of the effect of the electrical forces superimposed on the chemical adsorptive forces that contributes most toward understanding nonmetallic mineral flotation. The need for quantification of general rules for the flotation of nonmetallic minerals is so great that Taggart 5 with unmasked sarcasm suggested that after trying anionic and cationic collectors:

Jan 1, 1962

By Frederick N. Clark

These tests were made under the writer&apos;s supervision in the mining and metallurgical laboratories of the Massachusetts Institute of Technology, in the winter of 1888-89, by Mr. Robert C. Williams, of Marquette, Mich., assisted by Mr. J. B. Seager, of the

Jan 1, 1890

By E. E. Wark, J. Rogers, I. W. Wark, K. L. Sutherland

SOAPS have been used as collectors for many years, but only in the last eight years have other long-chain paraffin salts been used. It may be anticipated that these newer collectors will be used mainly with nonsulphide minerals, for which the xanthates and similar compounds are of little value. On the other hand, the xanthates are both cheap and effective for sulphide ores and seem likely to retain their present eminence in this field. During 1938 and 1939 two of us (E. E. W. and I. W. W.) commenced a comprehensive investigation of the principles underlying the use of paraffin chain salts as flotation reagents. This research was sponsored jointly by the University of Melbourne and a group of Australian mining companies.[t] A broad, semi quantitative survey was then made of the field covered in the present paper. This was followed in 1940 by further work by one of us (K. L. S.). In 1941 the investigation was taken over by the Division of Industrial Chemistry of the Commonwealth Council for Scientific and Industrial Research, Australia. Discovery of some principles upon which are based the flotation of minerals by paraffin chain salts was followed by their application in the development of processes for the recovery of certain strategic minerals from their ores. Promising results in the flotation of cassiterite from various ores will be described in a subsequent paper. THE PARAFFIN CHAIN SALTS The basic requirements for a "collector" in flotation are that it should form a film over the surface of the mineral to be floated, and that this film should be orientated so that hydrocarbon (nonpolar) groups form the effective surface. When modified in this way, the mineral surface possesses some degree of air avidity. All investigators would agree with Taggart, Taylor and Ince23 that such a film can be produced only if the collector compound contains an active (polar) group to attract it to the mineral surface as well as the nonpolar group. One section of this large class of polarnonpolar compounds is the paraffin chain salts: CH3(CH2) „X where X signifies a polar group that ionizes in aqueous solution. Though the compound can ionize, it may be a weak or a strong electrolyte, and the hydrocarbon chain may be in the cation or the anion (Table I). Many compounds of similar constitution are available, but the usual polar groups are: -CO2Na, -SO3Na, -SO4Na, - PO4Na2, or an aminonitrogen group, the

Jan 1, 1946

By Earl Hanson

FIRES in heavily timbered mines are disastrous, involving danger to both life and property. Some mines have been completely ruined or so heavily damaged that reopening them would not pay. Though few mines are entirely free from danger of fire, the risk is minimized by proper care and good design of plant. The Tintic Standard mine is at Dividend, Utah, in the famous Tintic mining district, about 60 miles south of Salt Lake City. The development of the mine was begun in 1907 by the late Mr. E. J. Raddatz and his associates. From the beginning, the work was hampered by high rock temperatures and the presence of high concentrations of rock gases such as carbon dioxide and nitrogen. Development work was carried on with great perseverance for nine years, and resulted in the discovery of ore in 1916. The total production of the Tintic Standard mine to Jan. 1, 1936, amounted to 1,664,388 tons of ore, having a gross value of .$61,996,719.

Jan 1, 1936

By Leah L. Naugle, H. G. Landau, H. H. Lowry

EVIDENCE has been accumulating in recent years, in part from the work of the Coal Research Laboratory, that coals belong to a family of natural polymers and that even in complex reactions the differences between coals are quantitative and not qualitative. This point of view leads to the expectation that if a series of coals were subjected to a closely controlled set of experimental conditions the results obtained should be related to the chemical analyses of the individual coals. The data accumulated over the past 10 years by the Bureau of Mines in its "Survey of Coke-, Gas-, and By-Product-Making Properties of American Coals," in what has come to be recognized as the Bureau of Mines-American Gas Association (BM-AGA) carbonization assay test,1-12 offer an unusual opportunity to check this conclusion. The present paper reports an analysis of the data on the first go coals and coal blends-including coals numbered I to 55b, inclusive -which have been carbonized according to a standard procedure at intervals of 100°C. from 500° to 1100° in either or both 13 or I8-in. cylindrical retorts." In Table I are given the name of the seam from which the sample was obtained, the analytical data used, and the reference to the original publication of the Bureau of Mines. The coals range in fixed carbon from 46.2 to 79.0 per cent, in volatile matter from 15.4 to 41.3 per cent, in ash; from 2.1 to 15.9 per cent, in moisture from o.8 to 19.7 per cent, and in total sulphur from 0.40 to 4.44 per cent; therefore the entire gamut of bituminous coals is represented. The petrographic nature of the individual coals is not considered in the following analysis, although both "normal" bright coals and splint coals are included in the samples studied. For information on the petrography of the coals and for further information characterizing the coals the original papers should be consulted. Although the coals that are included extend over the whole range of bituminous coals, they do not cover this range entirely adequately. In particular, only 13 of the go coals have moisture contents greater than 3 per cent. This concentration at low moisture values means that the effect of moisture, which is an important factor, cannot be determined with as much certainty as would be desirable. All the coals were not tested at every temperature and in both retort sizes. Only the first 30 coals were tested at 1100°, and only about 50 at the other temperatures, except at 900°, where nearly all of them were included. In the accompanying tables the actual number of observations entering into each correlation is given. In this study equations are given for calculating analyses, yields, and properties of coke and by-products from the coal analyses. To decide whether these equations are satisfactory it is necessary to know the accuracy with which these quantities were measured in the assay tests.

Jan 1, 1941

By L. W. McKeehan

Jan 1, 1934

By W. F. Hosford, E. W. Kelley

Deformation studies have been conducted at room temperature on single crystals of magnesium and magnesium alloys with thorium and with lithium. Single crystals oriented to suppress shear on the easily activated basal slip systems were deformed by plane-strain compression. Compression along the C axis was accommodated by {1011} banding. Compression perpendicular to the unconstrained c axis activated {1012} twinning, and, after virtually complete twinning, deformation continued by {1011) banding in the twinned material. Compression perpendicular to the constrained c axis was accommodated by the simultaneous operation of (1012) twinning against the constraint and (1011 ) banding. Although this orientation was favorable for {1010)(1210) prism and {1011}(1~10) pyramidal slip, these modes were not observed in pure magnesium or in Mg-0.5 pct Th. However, {10i0)(1~10) prism slip was observed in crystals of Mg-4 pct Li during compression perpendicular to the constrained c axis. Fracture in all materials occurred parallel to (1124) or {l~il) depending on the orientation and composition of the specimen. THE mechanical behavior of the hcp metals is strongly anisotropic. Although several slip systems have been reported the slip is cpmmonly in the directions of closest packing, the (1210),&apos; and this does not produce strains parallel to the c axis. Hence the inherent anisotropy. The deformation mode most easily activated in magnesium at room temperature is (0001)(1210)- basal slip. Also {1010}(1~10) prism slip and {1011)(1210) pyramidal slip have been reported, primarily at elevated temperatures.2"4 However, at room temperature the shear stresses to activate the prism and pyramidal modes are roughly a hundredfold greater than that required for basal slip.&apos;j4 Thus prism and pyramidal slip may be expected only under special conditions of loading. Strains normal to the basal plane can be produced by twinning, however. Many twinning modes have been reported for magnesium,&apos; with (1012) twinning the most common and relatively easy to activate. Magnesium can deform by (1012) twinning when stressed along the c axis jn tension, but not in compression. In contrast, (1011) twinning is activated by compression along the c axis and not by tension. In addition to primary twinning, secondary twinning or slip can occur within the reoriented material of primary twins.&apos; In general at least five independent shear systems must be active to bring about an arbitrary shape change such as that in the individual grains of a deforming polycrystalline material.&apos; Because basal slip can_ provide only two independent shear systems and (1012) twinning can only accommodate an extension of the c axis, other deformation modes must be active in magnesium for an arbitrary shape change to occur. The purpose of this investigation has therefore been to study the various deformation modes in magnesium at room temperature, with special emphasis on those modes that are less easily activated. The effect of the alloying elements, thorium and lithium, has also been investigated. In polycrystalline aggregates, unambiguous identification of deformation modes is extremely difficult and the direct evaluation of the resolved shear stresses to activate them is not feasible. On the other hand, uni-axial tension and compression experiments on single crystals may not activate some of the- deformation modes because basal slip and/or {1012) twinning cannot be suppressed in most orientations. However, it should be possible to activate all possible deformation modes using oriented single crystals and plane-strain compression. Identification of active deformation systems and evaluation of the resolved shear stresses required to activate them should be facilitated. Wonsiewicz and Backofen have recently completed an investigation of the plasticity of pure magnesium crystals at various temperatures utilizing plane-strain compression and selected crystal orientations. This technique has also been used in the present work. The seven orientations selected for study are indicated in Table I. Plane-strain compression along the c axis (orientations A and B) should activate some deformation mode _other than basal, prism, or pyramidal slip, or (1012) twinning. In orientations C and D, prism or pyramidal slip would be expected to take place. When the compressive load is applied perpendicular to an unconstrained c axis (orientations E and F) the three slip modes should be suppressed but not (10i2) twinning. In orientation G, basal slip should occur.

Jan 1, 1969

By William E. Ford, Edward Salisbury Dana

239, Contact-Gwiorneters. - The interfacial angles of crystals are measured by means of instruments which are called goniometers. The simplest form is the contact- or hand-goniometer one form of which is represented in Fig. 377. This contact-goniometer consists of a card on which is printed a semi- circular arc graduated to half degrees at the center of which is fastened a celluloid arm which may be turned to any desired position. The method of use of the goniometer is illustrated in Fig. 377. The bottom of the card and

Jan 1, 1922

By W. G. Fischer

This paper attempts to close the gap between extensive rock testing with field measurements and the mine operator&apos;s need for safe mine layouts and alternatives. It was found that many of the variables that influence mine geometry and worker safety are relatively unimportant while others are critical. The development of empirical relationships that tie the critical variables to the safe useful life of a trona mine layout and observations made in 140 production areas where the variables were researched over a 15-year period are discussed. The concepts presented may have applicability in mine design for other bedded deposits.

Jan 1, 1986

By C. A. Heiland, W. H. Courtier

The investigations described were made on a portion of Clear Creek basin near Golden, Colo. (-4 portion of the area under survey is shown in Fig. 1. The photograph was taken in the vicinity of station No. 2 of Line 11.) Three principal purposes were in the minds of the investigators: 1. To repeat with modern, more sensitive and more reliable instruments magnetometric placer investigations previously made. 2. To disprove the recently advanced theory that deposits of the glacial period have no pronounced magnetic effects. 3. To develop in detail the theory of the magnetic effects produced by placer deposits. Six years ago, the first magnetic observations were published, which proved that it is possible to locate gold-bearing channels with relatively crude instruments.&apos; Two years ago, K. C. Laylander published results obtained with similar instruments.2 The measurements of the latter were discussed by the senior author of this paper.3 At that time, however, the material available for such a discussion was somewhat scarce and not made with the most modern magnetic instruments, although very brilliant results were obtained. Therefore, the senior author felt that magnetic investigations should be made on very clear geologic conditions with the most modern instruments. Comparison of Magnetometers The junior author undertook this work in the spring of 1928. The magnetic field balances, for vertical and horizontal intensities, designed by Schmidt were used (Figs. 2 and 3). The scale value of these instruments was approximately 257 and 157, respectively. The middle

Jan 1, 1929

By Clarence S. Ross

INTRODUCTION THIS chapter on the rô1e of physical-chemical processes in ore deposition presents unusual difficulties because it attempts to discuss the theory of processes that are very imperfectly under- stood, but which are among the most fundamental problems now before the student of ore formation. It is generally believed that a great variety of ore deposits are in some way derived from igneous rocks; but we desire to know the mechanism of their splitting off from the parent magma, the physical and chemical character of the material that acts as a medium for transfer from magma to the point of deposition, the manner of deposition, and the methods of replacement and removal of the invaded rocks. This problem is difficult for the field geologist because it concerns forces that for the most part have long since ceased to act. It involves a complex system of which the time for completion extends from the first development of the parent magma through its intrusion, its slow cooling and crystallization, and the final escape of its last residuum, a time probably represented by millions of years. In space the processes extend from profound depths of the abyssal magma which can never be directly observed, through the horizons characterizing deep-seated igneous rocks and ore deposits; those formed at moderate depths; and ends with surficial ones and surface thermal springs. The geologist usually can study the effect at but one of these horizons: he must attempt to fit his puzzle together while seeing but a few parts at a time. Thus he must deal with many isolated phenomena, as if they were the result of many physical and chemical systems; when in fact his problem involves a single exceedingly complex system, and will only be understood when that entire complex system is understood. The geophysicist is handicapped because he must attempt to interpret an extraordinary complex system, involving physical and chemical conditions which he can never hope to duplicate fully, through the study of many exceedingly simple systems.

Jan 1, 1933

By Frank Rieber

The discovery that strongly magnetic bodies localized near the surface of the earth could be detected by the distortion which they produced in the resultant magnetic field marked the beginning of magnetic surveying methods. From an original ability to detect bodies of magnetic iron ore and the like when located very close to the surface, these methods have been extended until today they promise to give much information with regard to the structure of such slightly magnetic material as sedimentary rock containing only a very small proportion of iron.&apos; The recent extensions have been made possible through the development of more delicate instruments, and of methods for their use. From the original compass and dip needle, the design of apparatus has progressed until equipment is typified by magnetic balances capable of measuring the components of the earth&apos;s field to an extremely high degree of accuracy. It seems unlikely that the limit of such instrumental development has been reached. Just as the change from compass and dip needle has enabled the location of relatively minor changes in magnetic materials, so additional developments in the direction of increased sensitivity, as well as in greater dependability and constancy of operation, should reveal positively many slight changes which either escape notice in the present surveys or are so small that they cannot with certainty be separated from uncontrollable errors due to inconstant operation of the equipment. The ability to read smaller and smaller variations does not mean, of course, that deductions as to the causes of these variations will be made as accurately and definitely as is possible with the more pronounced anomalies.

Jan 1, 1929

By D. K. Crampton

THE study of copper alloys of the age-hardening type has received considerable attention, and, among the alloys which the authors have considered, those containing small amounts of nickel and phosphorus as essential constituents seem especially interesting. Such alloys have attractively great capacity for being hardened and also have relatively high electrical and thermal conductivity in the hardened state. In addition, it has been found that the increase in hardness and strength imparted by aging can be greatly augmented by cold-working, so that axcellent combinations of conductivity and strength are obtainable. In view of the possible importance of the alloys, it was considered desirable to investigate the solubility relationships in the copper-rich portion of the copper-nickel-phosphorus system. This paper presents some of the results obtained in this investigation to date and also gives properties of typical alloys that appear to be of commercial interest.

Jan 1, 1940

By S. G. Gibbs

A new method for predicting the behavior of sucker-rod pumping systems is presented. The pumping system is described by a flexible mathematical model which is solved by means of partial diflerence equations with the aid of computers. Polished rod and intermediate-depth dynamometer cards can be calculated for various bottom-hole pump conditions. The technique permits simulation of a wide variety of operating conditions, both normal and abnormal. The data generated with the new technique are useful in refining the criteria for design and operation of sucker-rod systms. INTRODUCTION Sucker-rod pumping systems are used in approximately 90 per cent of artificially lifted wells. In view of this wide application, it behooves the industry to have a fundamental understanding of the sucker-rod pumping process. Oddly enough, our understanding has been rather superficial. This is evidenced by the semi-empirical formulas which have been used as the basis for design and operation of sucker-rod installations. Thoueh- we have realized the limitations of our methods for many years, it has not been computationally feasible to use more refined techniques. With the advent and widespread use of digital computers, it is now possible to handle the mathematical problems associated with sucker-rod pumping. This paper summarizes a computer-oriented method which can provide greater insight into the sucker-rod pumping process. It is hoped that this technique, and techniques which may evolve from it, will prove to be the tool needed by industry to obtain the most efficient use of rod pumping equipment. THE MATHEMATICAL MODEL Prediction of sucker-rod system behavior involves the solution of a boundary value problem. Such a problem includes a differential equation and a set of boundary conditions. For the sucker-rod problem, the wave equation is used, together with boundary conditions which describe the initial stress and velocity of the sucker rods, the motion of the polished rod and the operation of the down-hole pump. Of these items, the wave equation, the polished rod motion condition and the down-hole pump conditions are of primary importance. Discussion of the mathematical model centers about these factors. ROD STRING SIMULATION WITH THE WAVE EQUATION The one-dimensional wave equation with viscous damp- is used in the sucker-rod boundary value problem to simulate the behavior of the rod string. This equation describes the longitudinal vibrations in a long slender rod and, hence, is ideal for the sucker-rod application. Its use incorporates into the mathematical model the phenomenon of force wave reflection, which is an important characteristic of real systems. The viscous damping effect postulated in Eq. 1 yields good solutions, even though nonviscous effects such as coulcomb friction and hysteresis loss in the rod material are present. Fortunately, the nonviscous effects are relatively small, so the viscous damping approximation used in the wave equation is adequate. The coefficient v is a dimensionless damping factor which is found in field measurements to vary over fairly narrow limits. For mathematical convenience the gravity term is omitted in Eq. 1. The effect of gravity on rod load and stretch can be treated separately, as will be noted later. Since Eq. 1 is linear, the legitimacy of this procedure is easy to demonstrate. POLlSHED ROD MOTION SIMULATION The motion of the polished rod is determined by the geometry of the surface pumping unit and the torque-speed characteristics of its prime mover. By determining the motion of the polished rod, we formulate an important boundary condition. From trigonometrical considerations it can be shown that the position of the polished rod vs crank angle 0 is given by (see Fig. 1) These equations are obtained from the general solution of the "four-bar" linkage problem and can be used to describe the kinematics of any modern beam pumping unit.&apos; If prime mover speed variations are disregarded, the angular velocity of the crank is constant, and Eq. 2 can be used to predict the position of the polished rod vs time. However, the constant-speed condition leading to constant crank angular velocity is only approached in practice: hence, it is better to make provisions for prime mover speed variations in the mathematical model. The speed at which the prime mover runs is determined by its torque-speed characteristics and the torque imposed upon it. The torque that the prime mover "feels" is the net torque arising from the polished rod load and the opposing torque from the counterbalance effect. The

By Richard McCaffery

WHEN we began the study of blast furnace slags we limited our work at first to a study of those slags containing only lime, alumina and silica. In our paper1 on some of the results of this first work, the solubility of. sulfur in slags containing no magnesia was reported and the question of sulfur solubility and slag viscosity discussed. There has been, for a long time, a very great difference of opinion among metallurgists as to .the effect of magnesia in blast furnace slags, and the literature is full of expressions of the most contrary opinions on the subject. As a result, our next publication2 developed the constitution of slags considered as a four-component system, silica-alumina-lime-magnesia, and advanced an explanation of slag structure which accorded with the facts and with scientific theory. The present paper continues our study of the general subject of slags. As blast furnace slags are included in the silica-alumina-lime-magnesia system, which is a particular case of four-component solutions, we have determined that there are 22 components (Table 1), which may enter into the silica-alumina-lime-magnesia system and that 10 or 12 of these components may be present in blast furnace slags which are within the ordinary ranges of composition. To have a very definite conception of the behavior of these components in a slag, we have developed the theory of the cooling of a four-component solution from the liquid state to the solid and the conclusions that we obtained have been made use of in this paper. On account of the importance of the four oxides and 18 compounds which enter into the silica-alumina-lime-magnesia system, some method of calculating the percentages of the various compounds that are present in the slag when the percentages of the oxides are given, seemed very desirable and we develop a method later herein for doing this, and finally we give illustrations of

Jan 10, 1926