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By E. C. W. Perryman

The recovery and recrystallization characteristics of superpurity aluminum have been investigated using electrical resistivity, X-ray line breadth, and hardness measurements for the former and the micrographic method for the latter. The three different properties recover at different rates and have different activation energies. The recrystallization results agree well with Avrami&apos;s theory and furthermore indicate that the perfect subgrains formed during recovery are not the nuclei for re-crystallization. WHEN a metal is plastically deformed, its physical and mechanical properties generally undergo considerable changes and by subsequent annealing these changes are partly or wholly annihilated. Thus, a recovery process can be discussed, taking this term in its general sense. In practice, however, there is reason to discriminate between two apparently different processes, one most easily followed at low temperatures, in which the properties return to an almost constant value between that of the cold worked and fully annealed material, and a second process in which the properties return to their original values before cold working and which is accompanied by the formation and growth of new grains having an orientation different from that of the matrix. In this paper the word recovery will be taken to mean the changes in some property as a function of annealing time which occur either without the appearance of new grains or under conditions such that the new re-crystallized grains are very small (= 2 microns), are very few in number, and substantially do not affect the property being measured. This definition is rather abitrary, for it will depend upon the sensitivity of the technique used for the observation of new recrystallized grains, which in the present work was about 1 to 2 microns. However, it is helpful to use the term recovery in this sense and to reserve the term recrystallization for the processes of nucle-ation and growth of new grains in the cold worked matrix. Although considerable work has been done on recovery and recrystallization, most workers have based their study on the measurement of one or perhaps two parameters. Since very small amounts of impurities have such a profound effect on the recrystallization characteristics of a pure metal, it becomes extremely difficult to correlate one piece of work with another. With this in mind, the present work on recovery and recrystallization was done on the same material. Experimental Procedure Material Used and Fabrication: The composition of the superpurity aluminum used throughout this investigation was 0.002 pct Cu, 0.003 pct Fe, 0.003 pct Si, and <0.001 pct Mg. The ingot was hot rolled to 0.250 in., annealed, and cold rolled to 0.034 in. A large number of reductions and intermediate anneals were carried out so as to produce material with a minimum of preferred orientation and maximum homogeneity. For the recovery part of the investigation, the final cold reduction was 20 and 80 pct and for the recrystallization part, 20 pct. After each pass in the cold rolling process, the material was quenched in cold water in order to keep the rolling temperature as near room temperature as possible. Annealing Procedure: For the recrystallization work, specimens 1x1 in. were cut from the 0.034 in. cold rolled sheet and a hole was drilled in each through which a wire was threaded to support it in the salt bath. The temperature of the salt bath was controlled to +2°C and the time taken for a specimen to reach temperature was approximately 5 sec. These 1 in. squares were then divided into three groups, one of which was given 5 min at 318°C and another 2 hr at 244°C. These treatments were such that recovery was almost complete and a well defined subgrain structure produced. Separate specimens of each group were annealed for different times at 301°, 318°, 355°, and 373°C, i.e., three specimens for each annealing time. The delay between finish of cold working and start of annealing was about 1 hr. For the recovery work, strips 0.062 in. thick were cut from the cold worked sheet, annealed, and then given the last cold rolling operation. This was done for each annealing temperature. By this means it was possible to minimize the delay between cold working and annealing. In general, all measurements were carried out within 1 hr of the last cold rolling operation. Annealing at low temperatures was done in an oil bath the temperature of which was maintained constant to +1°C. Electrical Resistivity Measurements: Strips 20x0.5x0.05 in. were machined and the electrical resistance measured using a Kelvin double bridge. Measurements were made in an oil bath maintained at 20rt0.1°C. The same specimen was used for the complete isothermal annealing curve.

Jan 1, 1956

By Jack A. Simon, M. E. Hopkins

GENERAL GEOLOGY Coal is defined as a combustible rock that originated in the accumulation and physical and chemical alteration of vegetation. Coal can be ignited and burned like the wood that was man&apos;s earliest fuel, but coal gives more heat than the same amount of wood and has many industrial uses. Unlike wood, coal is not generally found on the surface of the ground but is mined from the solid rock of the earth. Before taking up the occurrence, formation, and the unique character of coal in the rock sequence, let us briefly consider the general character of all rocks in the crust of the earth. Relatively little is known about the very earliest history of the earth, although a number of logical theories have been developed. Manned exploration of the moon and the rocks returned to earth continue to provide some answers to questions concerning the earth&apos;s origin and history. The period of earth history with which we concern ourselves here begins after great areas of water had evolved on earth and substantial land areas of once molten (igneous) rock existed. Weathering and other processes that attacked the surface of the rocks reduced them to small particles. Water provided by rainfall transported this material, ultimately, to large bodies of water where it was deposited. Thus was initiated the geologic sequence of sedimentary rocks that lie above the once molten igneous rocks. The crust and upper mantle of the earth are made up of several large plates along which differential movement (primarily horizontal) takes place. Such movements, although small, are occurring today. These horizontal movements are accompanied by vertical movements causing important changes in the relative position of the continents and oceans. Low-lying coastal swamps with favorable climates are ideal locations for coal accumulation and burial by river-borne sediments, and large areas

Jan 1, 1981

By Fred A. Anderson, George B. Wallace, Edward J. Slebir

Auburn Dam will be a thin, double-curvature concrete arch dam about 685 ft high. With a crest length of about 4000 ft, it will be the world&apos;s longest single-arch dam. The site is located on the North Fork of the American River about 40 miles northeast of Sacramento, Calif. Construction is scheduled to get under way in 1970. In planning for the design and construction of Auburn Dam (see artist&apos;s conception), the foundation material, with its various discontinuities, is being investigated and the structural characteristics of the rock mass evaluated. The investigation and testing programs will aid in defining the pertinent geologic features and their individual and cumulative influence on the foundation. The work includes geologic surface mapping, surface trenching, core drilling, geophysics, tunneling, excavating shafts and raises, performing in-situ tests, and conducting laboratory tests on core and block samples. Competent amphibolite is the predominant material in the foundation, but significant bodies of chloritic, talcose, and metasedimentary rocks, a strongly developed jointing pattern, faults, and shear zones also affect the deformability of the rock mass. A comprehensive rock mechanics program, closely coordinated with geologic investigations as well as the engineering studies, therefore is required The rock mechanics work is a combination of many analytical studies and experimental investigations. The experimental work includes laboratory tests on core samples from holes drilled for geological studies of the entire foundation and in-situ tests performed in selected areas. The laboratory testing program evaluates the general properties of all important rock types and aids in correlating many of the key structural features encountered within the foundation. To derive maximum benefit from the field tests, they are conducted in materials which represent a

Jan 1, 1970

By JAS. F. McCARTHY

THE present Hecla Co. is a Washington corporation; the Hecla Co. of Idaho was the old company. The older corporation owned two claims, the Hecla and the Katie May, and was incorporated for 500,000 shares of one dollar par value. The principal shareholders and officials of the older company were among the early mining men of the camp. Among the active officials were John A. Finch and A. B. Campbell. Among the directors and share- holders were Patrick Clark, J. R. Smith, Frank Upman, F. J, Kipp, Chas. Kipp, B. A. Kipp and Carl Landsee. F. J. Kipp and Carl Landsee are now directors of the Company. All of the others mentioned have died, but the surviving members of their families retain their ownership in the Company&apos;s shareholders. B. A. ,Kipp, who recently died, was the largest shareholder at the time of incorporation and Patrick Clark was the second largest shareholder. B. A. Kipp is a brother &apos;of F. J. Kipp, director of the Company.

Jan 1, 1924

By C. A. Crawford

NICKEL and the nickel-copper alloy, the latter generally referred to as morel metal, are available in a variety of wrought and fabricated forums, of which the following are regular commercial products: Form Monel Metal Pure Nickel Roc Hot-rolled; round, hexagon, Same as morel metal square, and flat shapes Cold drawn; round, hexagon, square, and flat shapes Hot-rolled wire rod Cold-drawn wire rod Plates Hot-rolled Same as morel metal Sheets Hot-rolled annealed Same as morel metal Hot-rolled annealed, pickled Full-finished Full-finished, No. 3 grind one side Full-finished, No. 4 grind one side Cold-rolled (annealed) Cold-rolled, No. 5 polished finish Strip Hot-rolled (flat rods) Same as morel metal Cold-rolled (annealed) Cold-rolled (unannealed) Tubes and pipe Gas-welded tube Seamless tube Seamless tube in I. P. S. Gas-welded tube Forgings Bolts, rivets Same as morel metal Nuts and washers Forging to order Castings Sand castings Same as morel metal Centrifugal castings Electrolytic Cathodes of high purity Anodes Cast anodes Rolled anodes Shot and block for 25 to 50-1b. pigs 5, 25 and 50-1b. pigs melting. Shot Shot

Jan 1, 1927

By Roman Šejnoha, Karel Mazanec

A pronounced tendency for delayed fracture zoas observed in the martensite structure of low-alloy steels in the as-quenched condition. Cracks of predominantly intercrystalline nature nucleated and propagated at stresses substantially lower than the short-titne tensile strength of- the steels, and were observed even in hydrogen-free speciunens. The occurrence of delayed fractures in the as-quenched condition is interpreted as a supevposition of the effect of free dislocations generated during the martensite transforlnation, and of a weakening of the prior austenite grain boundaries caused by dynamic shocks exerted on the boundaries by growing martensite plates. AN important metallurgical problem, connected with the production and use of high-strength steels, is delayed fracture in martensitic structures. Such fractures occur in quenched steels as a result of prolonged loading with external stresses far lower than the short-time tensile strength of the steel. The same effect can be produced by sufficiently high internal stresses: it is well-known that quenched structures will in some cases crack intergranularly at room temperature if not tempered quickly enough even in the absence of any externally applied stress. In Troiano&apos;s papers1,2 on delayed fractures in high-strength steels, the fundamental role of hydrogen migrating under the influence of multiaxial stress towards the nuclei of cracks was found. Fig. 1 shows the typical relationship between stress and the time to fracture found by Troiano in hydrogen-charged high-strength steels. On the other hand, Shurakov 3,4 explains the realization of delayed fractures in martensite as due to a "quasi-viscous" behavior of the austenite grain boundaries immediately after the martensitic transformation. 1) MATERIALS AND EXPERIMENTAL METHODS Two low-alloy steels of commercial purity were used for the experiments reported in this paper. Their chemical composition is shown in Table I. The heats were melted in a laboratory furnace, cast to ingots, forged to bars of 3/4 in. diameter, and annealed. Machined test pieces were heat-treated as follows: Ni-Cr-Mo steel held at 900°C for 30 min and quenched in oil; Mn-Si-Cr steel held at 900°C for 30 min and quenched in water. For the delayed-fracture tests, notched cylindrical test pieces, Fig. 2, stressed in torsion, and unnotched cylindrical tensile-test pieces, 1/4 in. diameter, were used. The specimens were normally loaded with a constant static load 45 min after quenching for the torsional tests and 10 min

Jan 1, 1965

By F. Keller, E. H. Dix, R. W. Graham

Aluminum alloys containing relatively small amounts of magnesium and silicon are of commercial interest because they are readily workable in the annealed form and may be hardened and strengthened by suitable heat treatment. An intermediate temper can be produced in these alloys by quenching after a Solution heat treatment and the alloy in this condition can be formed easily. Artificial aging is required to obtain the maximum mechanical properties but this aging does not cause distortion nor require elaborate heat-treating equipment. The hardening of the alloys after quenching is attributable in part to the retention of the compound Mg²Si in solid solution, while the maximum hardness obtained by subsequent artificial aging is attributed to the fact that the solid solubility of the compound Mg²Si in aluminum decreases with decreasing temperature. Considering the importance of aluminum alloys susceptible to heat treatment, it is surprising how few fundamental investigations have been carried out on the aluminum-magnesium silicide alloys. This paper deals principally with the solid solubility relations of the compound Mg2Si in aluminum and is the sixth paper of a series1 from the laboratories of the Aluminum Co. of America reporting the results of investigations of equilibrium relations in aluminum-base alloys made from high-purity aluminum."

Jan 1, 1931

By N. H. van Lingen

A laboratory stud], has been made to determine what factors affect the penetration rate of roller bits, diamond bits and drag bits in rock drilling with clay /water muds. The rather simple relations that exist when pressures in and around the borehole are equal become more conzplicated when under down-hole conditions the penetration rate is hampered by the existence of a pressure differential between the mud at the hole bottom and the pore liquid at cutting depth. Expressions that have been derived for both the penetration rate and the magnitude of the pressure differential in permeable rock together fully account for operating, rock, mud and bit variables. In impermeable rock a similar pressure differential is caused by the bit action itself. In all cases, the pressure difierential and the reduction in penetration rate increase with the effectiveness of the plastering at the bottom of the hole by mud particles. Where bits are employed whose action is largely that of crushing, however, the plastering may become even more effective owing to the addition of rock particles rubbed into the pores of the rock. With roller bits, a plastically hehaving layer may be formed, which causes a further reduction in penetration. In the case of bits whose action is chiefly scraping, moreover, penetration may be arrested by the bit&apos;s becoming balled-up. The various adverse effects are reduced by thorough scavenging of the hole bottom. This paper shows how with jet bits the efficiency of such scavenging may he improved by suitable choice of the position of the nozzles. INTRODUCTION The reduction in a bit&apos;s penetration rate with increasing depth of hole has been the subject of many investigations. Various investigators &apos;,&apos; have independently reached the conclusion that this reduction occurs not so much because the rock-breaking process becomes more difficult as it does because the lifting of the rock fragments is impaired by a fluid pressure differential holding the fragments down. When such a pressure differential can be avoided, as in air drilling and to a smaller extent in water drilling, penetration rates remain high. Although the range of applicability of these techniques is being extended, most oil wells still have to be drilled with mud. In this paper we present the results of laboratory experiments carried out to determine what factors govern the hold down effect encountered in mud drilling. In the course of this investigation, the well known importance of bottom scavenging came more and more into prominence. Not only may it reduce the magnitude of the hold-down forces, but also it appeared to be a means of preventing the accumulation of a plastic mass of cuttings and mud on the hole bottom and bit which may cause penetration to cease almost completely. So that the effects of fluid pressures may be more readily understood, the factors that govern penetration rate in the absence of these pressures will first be discussed. The effect of down-hole pressures will then be assessed for the case of permeable rock where fluid pressures are well defined, and it will be demonstrated how rock strengthening due to confining can be accounted for. Subsequently, fluid pressures in less-permeable rock will be examined; we will show that in impermeable rock it is the bit action that governs fluid-pressure distribution and hold-down. In the case of poor scavenging and/or high bit load. cutting cake manifests itself. The effect, like various others. appears to depend on the type of bit used. From the very beginning, therefore, we shall base our discussion on the three main types of bits used in rotary oil-well drilling— roller bits, diamond bits and drag bits. Since space is limited, it will be impossible to make more than a passing reference to many aspects of the problem. Moreover. certain relations that are not of primary irnportance to our argument will unavoidably have to be stated in a somewhat dogmatic fashion, and the experimental data on which these are based necessarily must be omitted. EQUIPMENT The drilling experiments were performed on three machines, of which one has been designed for the realistic simulation of down-hole pressure conditions. HIGH-PRESSURES MACHINE In this machine (diagramed in Fig. 1) the mud, pore and confining pressures can all be adjusted independently. The foil-covered rock sample contained in the inner pressure vessel is confined by oil that is pressurized by means of a hand pump. The pore space of the watersaturated sample is connected to an arrangement which keeps the pressure in the pore space constant regardless of the rate of filtrate flow through the sample.

Discussion of the paper of W. A. Forbes, presented at the New York Meeting, October, 1913, and printed in Bulletin No. 82, October, 1913, pp. 2477 to 2514.. SAMUEL K. VARNES,* Steelton, Pa.:-We have a gas-cleaning plant consisting of a, centrifugal dry dust catcher, and two rain-type wet scrubbing towers, 25 by 60 ft. each, for rough cleaning of blast-furnace gas. This plant was put in early in 1910, with the intention of cleaning gas for use in hot blast stoves and under boilers, and was so used for several months. Soon after it went into service, the blast-furnace men complained that they could not get as high blast temperatures as they had obtained when using dirty gas. It was decided to run a series of careful tests to determine if this were true and to what degree the apparent results might be affected by other conditions. About 60 tests were run, covering a period of five months, and at the end we came to the conclusion that it did not pay us to scrub the gas for stoves and boilers. The tests were all run upon a single stove, no boiler tests being made, but the conclusions of the stove tests being applied to the boilers. The furnace burden was practically the same for all the tests and averaged: Per Cent. Daquari and other hard ores 57 Nodules 13 Raw Mayari ore 25 Mill cinder and scale 5

Jan 12, 1913

By B. L. Landrum, P. B. Crawford

The rise of a new laboratory model for studying tran-sient fluid flow problems, is described. The theory of he model is based on the analogy between the equa-ions which describe the flow of compressible fluids in porous media and the conduction of heal m solids. The "thermal model" is used to study the Iransient Pressure distributions during fluid displacement in five Standard well patterns. The studies indicate quantita-ively how die pressures change with lane at any poit in the reservoir. It was found that, in general, the equipressure contours are more radial about the wells early in the program than after steady-state conditions are established. In addition two studies of fractured five-spot patterns are presented to illustrate the opplicability of the model for a wide range of reservoir conditions. INTRODUCTION In reviewing the oil recovery techniques involving fluid displacement it was found that a very considerable quantity, if not all of the fluid within the pattern, mav be displaced (during a time-dependent or transient period rather than the usually applied steady-state conditions. Since the oil is displaced during a transient period, it was believed desirable to study the nature of the transients for several of the commonly used fluid displacement patterns. A literature review indicated fairly complete studies of the streamlines and isopotentials for steady-state: yet few data were available on the transient displacement process. Several simulated steady-state multiwell displacement programs were carefully mapped by Foster and Lodge on an electrical conducting sheet as early as 1875, hut the more recent work of Muskat provides the best source for steady-state phenomena having direct petroleum production applications. In order to study the transient phenomena a new lab-oratory model was developed which is based on the similarity of the equations that describe the flow of fluids and the conduction of heal. The equations describing heat flow were developed early in the nineteenth century. Regorous solutions tor most transient problems are in gcneral complex and usually limited to fairly restricted houndary conditions.2 the thermal model may be used to obtain approximate solutions for many transient problems without some of the restrictions required for analytical solution. The application of the analogy between heat conduc-. tion in solids. electrical flow and fluid flow, in a porous media has long been recognised. Techniques originally developed for the solution of heat conduction prol?lems have in many instances proved useful in ohtaining solutions to fluid flow prohlcms. Ir is not surpri5ing then that a heat conduction or thermal model might bf usefull in sludying transient fluid flow. As an example ol the problems suitable for the study with the thermal model, transient pressure distributions during fluid displacement programs are studied for the five-spot, line-drive, staggered line-diibe. seven-spot 211 two fractured patterns. A model was constructed of an iron plate of geometry similar to the reservoir patterns under study. The principle of mirror images as suggested by Bryan was employed in shaping the model. A temperature differential was obtained by soldering two sections of copper tubing to the plate at points analogous to the well location in the field. Hot and cold water was passed through the tubing. The temperature distribution, analogous to the pressure distribution in the field. was obtained a a function of time from thermocouplcs distributed over the plate.

By E. A. Lucero, H. E. Robbins, T. H. Dudley

EL Salvador mine of Andes Copper Mining Co., E subsidiary of Anaconda Co., is in northern Chile about 18 miles north of Potrerillos, 7825 ft above sea level. Initial production is planned for the first half of 1959. Plant capacity will be 30,000 tpd, and there are 308,835,000 tons of proven ore reserves, averaging 1.49 pct Cu. The Inca adit is being driven as part of the mine-to-mill haulageway. Because of the overburden it is planned to mine the deposit by block caving. Ore will be dropped from upper gathering levels through ore passes to the Inca adit, through which it will be transported out of the mine to the primary crushing plant located a half mile from the portal.

Jan 3, 1958

By Arthur B. Cummins

Diatomite is a siliceous rock of sedimentary origin, which may vary in degree of consolidation, but which consists mainly of the fossilized remains of diatoms. These are microscopic algae of the order Bacillaria. Diatomite is a unique form of silica, there being nothing else found in nature or produced by the manufacturing arts, that has its characteristic physical structure. There are numerous sediments which contain some diatom residues, admixed with a substantial amount of other materials-clay, carbonates or silica. While these are classified as diatomaceous silts, shales, or mudstones, they are not properly diatomite, a designation which is restricted to material of such qualities that it is suitable for commercial uses. The terms diatomaceous earth and kieselgur are synonymous with diatomite. The expressions infusorial earth and tripolite are obsolete. Diatomaceous silica is a definition best used to distinguish the basic component of diatomite, that is, the substance of the silica shell itself and is the major constituent of beneficiated diatomite or processed diatomaceous products. Some highly indurated materials, such as cherty shale, porcelanite, and opaline cherts which have resulted from diagenetic changes cannot be considered as diatomite although they may have been derived therefrom. On the other hand, diatomaceous oozes or loose sediments consisting mainly of diatom residues with or without much organic matter are source materials in process of becoming diatomite. Composition and Properties Pure diatomite is composed of opaline or hydrous silica, with small amounts of associated inorganic components-alumina, iron, alkaline earths, alkali metals, and minor constituents, all of which may occur in solid solution or as an essential part of the opal complex. Crude diatomite on the other hand may contain variable amounts of organic matter and soluble salts, and the usual contaminants of sedimentary formations-particles of rockforming minerals, sand, clay, or carbonates. As occurring in nature, diatomite contains an unusual amount of free water, which may vary from 10 to 60 pct or more. Diatomite, in the dry deposits which are characteristic of most of the important world deposits, occurs as a lightweight, comparatively light colored, "chalklike" material. The apparent density (dry basis) in situ varies from 20 to 40 lb per cu ft. The structure may be either massive or finely stratified. The earth is highly porous, usually soft and easily friable. It is nonreactive with acids and may be tentatively identified by the above characterizations. Confirmation is by microscopic examination which readily reveals the nature of the material. In deposits which contain organic matter the appearance of the material is totally different. The color may vary from light tan or gray to brown, greenish or nearly black. There is frequently difficulty in distinguishing it in the field from peatlike materials, but the difference is readily apparent after calcination. Powdered diatomite or diatomite products have an apparent density (loose weight) of 5 to 16 lb per cu ft, wet densities of 10 to 30 lb per cu ft, specific gravities 1.9 to 2.35, index of refraction 1.42 to 1.48. Diatomite is essentially micro-amorphous, but does show some tendency toward orientation in structure after a cristobalite pattern. Amorphous silica has been considered as a random association of cristobalite crystallites, the size of which are only slightly larger than a unit cell.20 The prop-

Jan 1, 1960

By M. H. Forester, John D. Cooner

ANTHRACITE ALTHOUGH the unmined anthracite will last for approximately 150 years, most of the thicker and cleaner coal beds have been almost entirely first-mined and pretty well robbed, leaving much of the present and future production to come from thin and dirtier beds. Herewith is a section of one of the dirty beds being mined in the Wyoming region [ ] This section shows that 45.8 per cent of the bed is made up of impurities and that the 45 in. of coal in the bed is in five benches, the thickest of which is 19 inches. In some localities of the anthracite region there are 14 beds of minable coal. Orderly and proper mining of the coal makes it necessary to rob or second-mine-almost all beds have already been first-mined-in sequence from the top downward. Therefore the robbing of the few remaining portions of the thicker and cleaner beds is in many instances being held up by the mining of the overlying thin and dirtier coal beds. Impurities Impurities consist of fire clay, slate, rock, and bone. The latter, which is black, contains 40 to 60 per cent carbon and often resembles good coal. In some beds there are also bands of "blue" coal, which, as the name implies, is of a bluish slaty color. Although much of this "blue" coal has a carbon content almost as high as the good anthracite, it is not

Jan 1, 1943

By C. L. Ray, R. E. Baarson, H. B. Treweek

As an example of nonmetallic mineral flotation, the separation of several pegmatite minerals will be discussed in considerable detail, from both the laboratory-testing and plant-operation standpoints. The pegmatites have been chosen to illustrate the practicality of the selective separations of the minerals in a complex nonmetallic ore and, in so doing, to set forth a summation of the flotation art and technology which is applicable in part to the beneficiation of several less complex nonmetallic ores. In addition, a brief summary of descriptions of other nonnietallic mineral flowsheets and separations is included. Some of the industrial minerals now being concentrated by froth flotation methods commercially, or in the laboratory, are listed in Table 1. GENERAL CONSIDERATIONS There are two classes of chemicals that are normally utilized as collectors in froth flotation separations of nonmetallic minerals. These are defined as anionic and cationic and are typified by the fatty acids and amines, respectively. The fatty acids are selective to those minerals that have a high concentration of positive surface charges, such as the various calcium minerals typified by calcite, phosphate rock, and fluorspar. The amines are selective to those minerals with a high concentration of negative surface charges, such as silica sand and silicates. It should be noted, however, that by using various inorganic chemicals, a new or synthetic surface can be placed on specific minerals which produces different characteristics, thereby reversing the flotation reagent required for separation. The polar end of the collector attaches to the mineral surface either by chemical or physical adsorption; the nonpolar unreactive end is oriented away from the mineral surface. The result is a hydrophobic coating at the mineral surface which causes attachment to air bubbles. It is this surface condition that permits the floating of minerals which normally sink in water. In order to utilize these fatty acids and amine derivatives, several conditions .must be fulfilled. Before there can be a selective flotation process,

Jan 1, 1962

By J. J. Mulligan, F. F. Colcord, E. F. Kern

The electrolytic separation of silver and gold has been practiced by the refineries in the United States for a good many years, and probably because of frequent visiting between officials of plants and the consequent exchange of views, operations in the various silver and gold refineries are very similar. We find, for instance, they practically all use electrolytes of approximately the same composition, which, no doubt, is more the result of experience than of studies of electrolytes. At the new electrolytic parting plant of the U. S. S. Lead Refinery, Inc., East Chicago, Ind., considerable attention has been given to the composition of electrolytes, especially to their conductivity and their effect on the character of the silver deposit. We are not aware that anything has been recently published on this subject and are, therefore, presenting such data as we have with the idea that, although it will not be wholly new, it may stimulate interest in the subject. Effect of Copper Content on Conductivity The first work was to determine the specific conductivity of silver nitrate and copper nitrate solutions. Concentrated solutions of silver nitrate and copper nitrate were prepared by dissolving analyzed chemically-pure salts in distilled water, and determining the silver and copper in each. Definite amounts of the concentrated solutions were taken, mixed and diluted to a definite volume. The silver and the copper were determined in each of these solutions and the conductivity was then determined. The plotted results are shown in Figs. 1 and 2. The effect of increasing quantities of silver and copper is readily seen. A comparison of the two sets of curves shows conclusively the benefit of holding the copper content of the electrolyte above 5C g. per liter, as its effect is to increase greatly the conductivity in an approximate propor-

Jan 1, 1926

By William G. Pariseau

The flexure of geologic strata, a phenomenon of interest to geologists and mining engineers alike, is examined as a sheet bending problem in Coulomb plasticity. Fonnulae for the distribution of stress, strain, and displacement increments; volume change; change in the length of the central surface; and power of dissipation, as well as for the neutral surface shift are given. Strains of any magnitude are considered. The analysis shows that deeply buried strata may bend and develop "tensile" cracks under generally compressive states of stress. It is also shown that bed separation and high capacity props are desirable in mechanized longwall mining, a result in keeping with operating experience. Although speculative at this time, the analysis provides a rational working hypothesis as regards the problem of strata flexure and control. | he purpose of this paper is to present an analysis of the flexure of geologic strata as a problem in the bending of a sheet of material failing in accordance with a Mohr-Coulomb criterion. The flexure of strata has an obvious academic interest to the geologist concerned with the mechanics of folding. It is of interest to the economic geologist as it relates to the structural control of certain types of ore deposits. It has an intimate association with mine subsidence phenomena, and is of concern to the mining engineer. Strata flexure is also the dominant feature of roof behavior about longwall workings. An improved understanding of strata flexure through a rational mechanical analysis thus appears desirable not only from the academic view but from the economic one as well. In the field, the most commonly observed feature of folding, subsidence, and longwall roof behavior is the permanent and therefore inelastic nature of the strata movement. Fig. 1 illustrates the physical disposition of strata in the vicinity of a longwall face. Inasmuch as most rocks (with the possible exception of certain evaporites) do not exhibit significant viscoelastic behavior, at least not over time spans of engineering interest, a plastic analysis is indicated. The analysis is meant to apply to strata whose deformation is dominantly that of bending such as might be expected in the remote roof about a longwall face.

Jan 1, 1970

By R. Kerby, T. R. lngraham

The rates of cadmiuln cementation from buffered solutions were studied on both the cylindrical and circular faces of a rotating zinc disk. The activation energies are equivalent on both surfaces, but the rate is more rapid on the cylindrical face. At higher temperatures and at pH values above 6.4, the rate of deposition increases because of an increase in the cathodic area of the deposit. The rate may also be increased by decreasing the thickness of the diffusion layer by rapid stirring. The presence of small amounts of copper, cadmium, lead, iron, or aluminum in the zinc does not affect the cementation rate, but when srnall amounts of copper, cobalt, and arsenic were present in the solution cadmium deposition ceased shortly after it started. Small amounts of copper in solution become cemented with the cadmium to form a coarse deposit of Cd3Cu. When zinc ores containing cadmium are processed for electrolysis, the cadmium appears with the zinc in the leach liquors. Because of the discharge potential of the cadmium ion and the hydrogen overvoltage on metallic cadmium, the cadmium ion must be removed prior to zinc electrolysis to prevent its codeposition. Cadmium is usually removed from acidic zinc sulfate solutions by cementation on zinc. When zinc sheets are used with the appropriate conditions of pH and temperature, a finely divided, high-purity cadmium powder is obtained; it floats to the surface with attached hydrogen bubbles and, after careful washing, may be processed directly to a marketable product.&apos; The reaction on zinc sheets is relatively slow because of the limited amount of exposed cathodic area on the sheets. A much more rapid reaction is obtained when zinc powders are stirred into the solution, but this procedure does have a potential disadvantage: some unreacted zinc may be trapped in the cemented cadmium and thus lower its grade.1 The equilibrium constant at 25°C for the displacement of cadmium by zinc is of the order of lo", which indicates that at equilibrium the displacement would be essentially quantitative and no back reaction need be considered. This indication is not entirely true, however, because in the presence of oxygen any loose cadmium which is out of contact with metallic zinc tends to redissolve after cementation.&apos; The overall effect is much the same as that to be expected if the equilibrium constant were much smaller. Previous experimental work on cementation reac- tions3 is in general agreement that the rates of cementation usually follow first-order kinetics. The metal on which cementation occurs is considered to consist of anodic areas from which metal dissolves and cathodic areas onto which the reactive metal is cemented. For the reaction to continue, the cemented deposit must remain open and porous for the removal of ions. Usually, the deposited metal influences the rate of cementation; when it blocks the pores in the deposit, the rate of cementation will be decreased. Alternatively, when the cemented metal grows as den-drites or as coarse powder the cathodic area is correspondingly increased and the rate of cementation increases,3 Thus, it is only during the initial stages of cementation, prior to the development of deposit effects, that the kinetic behavior of the reaction may be studied without ambiguity. In this paper, experiments will be described for cementation of cadmium from dilute solutions onto the surface of a rapidly spinning zinc cylinder. The effects of ionic concentration, disk rotation speed, temperature, and impurities will be described. APPARATUS AND PROCEDURE The apparatus used for the experiments was described in a previous paper.4 It consisted of a 2-liter vessel in which the contents were protected, against oxidation, by a stream of prepurified nitrogen. The vessel was immersed in a water bath which controlled

Jan 1, 1970

By James A. Barr

Phosphate rock is a natural rock containing one or more phosphate minerals usually calcium phosphate, of sufficient purity and quantity to permit its use, either directly or after beneficiation in the manufacture of commercial products.1 The principal minerals in phosphate rock have the apatite structure which may be represented by the type formula: Ca10(X2) (PO4)6 where X represents the hydroxyl group (OH), chlorine or fluorine, either singly or collectively. The calcium may be partly replaced by sodium, magnesium, and other positive ions such as manganese, strontium, lead, uranium, cerium, yttrium and other rare earths. The PO4 radical may be partly replaced by small quantities of UO4, AsO4, SiO4, CO3, SO4, or Vo4. A typical commercial rock is usually a calcium phosphate containing 3 to 4 pct fluorine, the major impurities being limonite or other iron oxides, clay, aluminum phosphates and silica as quartz sand. A little vanadium is present in most of the domestic rock deposits (except the Tennessee Brown Rock), according to Jacob, Hill, Marshall and Reynolds! A little uranium occurs in the Florida leached zone, as will be brought out later. The chemical analyses are reported as P205, or tricalcium phosphate Ca3(PO4)2, the latter often designated by the trade name BPL (bone phosphate of lime). Commercial analyses usually report iron and alumina as oxides, lime as CaO and silica or insoluble. Colony3 examined many samples of apatite, staffelite, dahlite and American phosphorites and concluded that all have identical X-ray diffraction patterns. The phosphates in the phosphate rock have very minute crystalline structures. The mineral apatite Ca3(F.Cl) (PO4) 3 is the principal primary source of the element phosphorus, and occurs widely distributed in igneous rocks but rarely in a minable mass. Only about 12 pct of the world production of phosphate rock comes from primary apatites; the remainder is derived from secondary phosphorites. These phosphorites have been formed by the alteration of sediments by solutions containing phosphoric acid. Such solutions have come from the weathering or leaching of igneous rock containing apatite, bone deposits of prehistoric animals, marine life or guano deposits. These phosphorites are mostly alterations of phosphatic limestones. The sedimentary phosphate deposits are of marine origin and may have been enriched by subsequent solution of the more soluble calcium carbonate by waters containing carbon dioxide, by physical concentration by wave action, and by redeposition of the dissolved phosphate ions. Uses of Phosphate Phosphorus is the spark of life and is the structure builder and one of the main elements of plant food (fertilizer). Without phosphorus, life cannot exist. A "complete" plant food[t] in addition to phosphorus compounds contains potash, which acts as a catalyst to convert nutrients to useful forms, nitrogen to supply the growth element and many minor elements. The cycle of supply of phosphorus is from the apatite to solution and soil, absorption of plant life, decay and return to the soil or by animal life feeding on the plants. With insufficient supply of phosphorus in vegetation, life is not prolific. If crops are removed from

Jan 1, 1960

By Richard D. Hagni

Abstract-Although the ore microscopist routinely examines polished sections to determine the mineralogy and texture of ores, his importance to the solution of problems peripheral to geology is not always fully realized. The techniques which he uses can be applied with little modification to the solution of a wide variety of beneficiation problem. By extending his studies beyond those normally considered to be of interest to the geologist, he can include examinations of polished sections of selected mill products. This is a logical extension, because the minerals and textures in the polished sections of ores are the same as those in mill Products. The mill dressing engineer should be more aware of the types of beneficiation problems that can be solved by the ore microscopist and what the ore microscopist can do for him. A greater degree of cooperation between the ore microscopist and the mill dressing engineer can be of significant mutual benefit. Ore microscopy holds an advantage over chemical analysis, because the interrelations and combinations of the mineral constituents of an ore or mil1 product can be visually determined. This advantage provides solutions to many beneficiation problems. Locking is a type of beneficiation problem that is particularly amenable to ore microscopy. The percentage, type, and distribution of locked particles can be readily determined with the aid of an ore microscope and an estimate made of the extent of additional grinding required for liberation. The extent of intimately locked types, which no reasonable amount of grinding will liberate, can also be evaluated. Mineral coating conditions, free particles of a deleterious mineral, and free particles of a valuable mineral held in floculated clusters of gangue are other features that can readily be observed. In some instances, visual examination may show that the problem is not one of locking. Photomicrographs illustrate the variety of beneficiation problems for which the ore microscope is applicable. These problems and their resolution demonstrate the importance of the instrument and show the value of close coordination between the mill dressing engineer and the ore microscopist.

Jan 10, 1978

By Edward Adarns Richardson

As developed up to the end of the Great War, an airplane was essentially a mechanism of wood and fabric, joined and held together by metal fittings and fastening. The engine and accessories, wire for wheel spokes and other tension members, and the occasional use of metal for inter-plane struts and the shafts of surface controls required some metal, but essentially it was a wood and fabric structure. Attempts had been made to use metal for other purposes, such as struts in the drag-trussing of wing panels and for short interplane struts, and Junkers had produced an airplane of iron in 1915. By 1917 he was using steel tubes and duralumin sheets, securing noteworthy advantages aerodynamically and from the standpoint of weight and upkeep. He was a pioneer along lines in which progress is still being made. Principles of Airplane Construction The loaded weight of airplanes ranges from 500 lb. for the light plane of which we heard so much a short time ago, to about 40,000 Ib. The great majority of planes range from 2000 to 10,000 Ib. Of this weight from 15 to 30 per cent. is for the dividend-earning load. This percentage is so low that every per cent. saved on the rest of the weight increases the pay load from 3 to 6 per cent,. The economic value of every pound that can be saved in designing or constructing a plane is sufficiently great to warrant spending money on refined methods of structural analysis, materials of superior strength properties for a given weight, methods of manufacture which may make possible the use of refinements in structural design, and the like, to an extent unknown heretofore. The weight of the airplane, without fuel, oil and crew, and pay load, ranges from 50 to 65 per cent. of the total weight loaded for planes suitable for commercial use. It is doubtful if the structural weight will ever be brought down to as low as 40 per cent. for commercial planes. The airplane may be roughly divided into: (1) Power plant, which includes engines, radiators, cooling water, oil and fuel tanks, piping, propellers, engine-starting systems, pumps, super-