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By Hugh Rose

JAY A. CARPENTER, Tonopah, Nev: (communication to the Secretary*).-This description of the Santa Gertrudis mill is of great interest to the operators of similar silver mills in Nevada. At the San Francisco meeting last September there were two excellent papers presented on Nevada silver mills; one by A. H. Jones on The Tonopah Plant of the Belmont Milling Co., and the other by E. E. Carpenter on Cyaniding Practice of the Churchill Milling Co., Wonder, Nev. At the same meeting, I presented a paper on-Slime Agitation and Solution Replacement Methods at the West End Mill, Tonopah, Nev., covering this .particular feature of our milling practice. A comparison of the data presented in these four papers is interesting in that, while the general design and practice is much the same in all cases, there is a wide difference in the design and practice in the various departments of 'the mills. It is to be regretted that Mr. Rose did not round out. this excellent article by following Mr. Jones's and Mr. Carpenter's' lead in giving the average gold and silver content of the ore milled and the resulting tailing, with the consumption of chemicals and the? cost of milling. The practice of the Santa Gertrudis mill in the use of ?cyanide and zinc offers an interesting comparison with that of the Nevada mills, and a discussion of this point may bring out the reasons for the differences that exist.

Jan 12, 1916

Diffusion in Solid Metals. BY ROBERT F MEHL (Institute of Metals Division Lecture Tech Pub 726 in Metals Tech, Aug , also Trans, vol 122 22,500 words ) Diffusion in solid metals constitutes one of the important fundamental phenomena in metallurgical behavior Apart from its obvious importance in processes such as chromizing, carburizing, nitriding and calorizing, it plays an important part in the processes of homogenization, age-hardening, and transformations in steel, its scientific importance is no less great Diffusion may occur within a grain, along a grain boundary, or upon a surface, though the exact and even the relative values of these separate processes are known for only a very few cases The requirement of solid solution formation presents the possibility of identifying solid solution phases by a study of diffusion layers Some distortion accompanies diffusion, leading to little¬ understood grain-size changes Distortion assists diffusion though usually it dis¬appears before diffusion has become extensive In a binary system the rate of diffusion is the more rapid in the lower melting metal Many of the published data are too qualitative to permit sound scientific conclusions Age-hardening data may be treated as diffusion data and rates of reaction in steel could profitably be studied from this point of view Studies on diffusion are of great importance to the develop-

Jan 1, 1937

By Samuel Shallcross

TO principal function of the Bell limestone mine, of the American Lime & Stone Co., at Bellefonte, Pa., is to supply raw material to the company's modern rotary kiln plant at Bellefonte. Because mining costs are naturally higher than many open quarries with more favorably lying strata, it cannot compete, except to a limited extent, in the markets for road material and fluxing stone. In the broad sense, mining does have an advantage over the average open quarry when the end products are designed for and controlled by process and final inspection for the exacting demands of the industrial and chemical markets. Approximately 80 per cent of the output of the Bell mine is sold in the industrial and chemical markets. And as higher standards are set each year for construction and agricultural work, the remainder of the mine output goes to these two classes. Mining produces more fines than open quarries, and these fines are difficult to market; on the other hand, owing to absence of contaminating clay and impure rock, a greater percentage of the output of a mine is marketable. Because of the great production of fines, rotary kilns for lime burning are necessary when the stone must be mined. In 1921 the American Lime & Stone Co. operated 19 quarries and 72 lime shaft kilns spread over an area of 40 miles between Bellefonte and Altoona, Pa. At that time the lime-production capacity of the 72 kilns amounted to approximately 700 tons per day. After 15 years the company operates three rotary kilns and six shaft kilns, with a combined output of approximately 500 tons of lime per day, concentrated in its single Bellefonte plant (Fig. 1). Its only stone-producing plants are now the limestone mine at Bellefonte and a construction-stone open quarry at Union Furnace, near Tyrone, Pennsylvania.

Jan 1, 1936

By George A. Johnson, Leon H. Banks

The Missouri-Kansas Zinc Corpn., operating in the Waco district, 15 miles northwest of .Joplin, Mo., owns large tailing piles made during milling operations of the years 1918-28 by the Butte-Kansas, Acme, and Barnsdall mining companies, whose holdings have been purchased and consolidated under the ownership of the Missouri-Kansas Zinc Corpn. These tailings had been considered too low in value to be worth retreating by the ordinary methods. C. Erb Wuensch, consulting engineer of the Missouri-Kansas Zinc Corpn., noted the difference in the type of tailing from upper-level and lower-level ore. The latter contained hard lime chats. He also found that mill losses had been due to particles of blende on the corners or sides of the chats and to the existence of soft, porous, cellular, lime chats containing varying amounts of blende. He conceived the idea that a quick grind in rolls or hall rnills might change the type of the rnaterial so that jigging could rnake a clean tailing for discard and a partly concentrated product sufficient in blende content to justify the expense of fine grinding in hall mills to free the mineral entirely. A laboratory was equipped with the necessary machines and the writers were assigned the problem of developing a method of retreating the tailings. Laboratory Testing From preliminary drill sampling of each pile was obtained the blende content, the soluble sulfate content, and the general characteristics of the material to he treated. The tailings were a mixture of lime and flint with some shale. Visual examination showed most of the blende to be in the dolomite and very little in the flint, although there were some flint particles with blende on the cleavages. The blende was found as particles on the corners or cleavage faces in one type of chat and in another disseminated in a soft, porous, cellular lime. Because of the porosity of the latter type of chat, the apparent specific gravity, under hindered-settling conditions, is less than that of a solid piece of lime or flint. That it,

Jan 1, 1930

By John C. Calhoun, Alfred Chatenever

An exploratory study wap made to examine the possibilities of a visual approach in investigations into microscopic mechanisms of fluid behavior in porous media. Appropriate apparatus and techniques were developed so that microscopic phenomena could be recorded on color movie film as well as be observed visually. The observation flow cells in which tlie fluid behavior studies were made were essentially single-layered matrices of spheres between plates. sometimes all-glass, sometimes all-Lucite and sometimes a combination of the two. The fluids were limited to water and a filtered crude oil. Two flow regimes were observed during the flow of the immiscible liquids: channel flow and slug flow. In the former, transport was effected through stable networks of interconnecting channels; and in the latter, part of the movement took place in the form of slugs. Under certain conditions, flood-front patterns were found to be different depending upon which liquids were the displacing and displaced phases and not depending upon whether the matrix was water-wet glass or oil-wet Lucite. Residual formations of oil and water were observed and are described. Some of the ramifications and significance of the ohservetl phenomena are discussed. INTRODUCTION In recent years considerations of microscopic mechanisms of fluid flow in porous media have taken on greater significance. Much needs to be learned before the fundamentals of petroleum technology are completely established. For example, many unanswered questions exist in connection with relative permeability, displacement phenomena, residua! fluid formations. flow structure, etc.; and further analytical mathematical formulations are seriously indicated. It is hoped that systematic investigations into the microscopic mechanisms connected with the behavior of fluids in porous media will shed some light on some of the problems extant. Until recently microscopic mechanisms have been considered almost exclusively as speculative hypotheses. Within the past few years, however, the problem has been submitted to a limited number of experimental investigations. Nuss and Whiting' made some studies on the pore-space geometry of sandstones and limestones by impregnating cores with an inert plastic and leaching the solid matrices to leave behind plastic models of the pore spaces. SchaeferZ traced pore spaces microscopically through lengths of limestone cores by cutting away thin sections from the exposed faces normal to the line of view. In 1949 two projects were organized in which dynamic flow phenomena were examined microscopically to uncover microscopic mechanisms. One was set up at the Pennsylvania State College where Lowmanb bserved heterogeneous fluid flow phenomena in capillaries. The second was the American Petroleum Institute Research Project 47B at the University of Oklahoma where microscopic studies of dynamic fluid phenomena in synthetic porous matrices have been made by visual observation and cinephotomicrography.' It is with the latter that this paper is concerned. treating the techniques involved and the observations made. TECHNIQUES Observation Flow Cells The observation flow cells formed a focal point in the techniques employed. Essentially, these were matrices composed of a single layer of spheres sandwiched between two flat plates. This design was arrived at after a series of pre-

Jan 1, 1952

By F. O. Jones

The capabilities of small proportions of divalent cations, such as calcium or magnesium, for controlling clay blocking are reported. Potentially sensitive formations can be exposed to fresh water if at least one-tenth of the salts dissolved in both the native water and invading fresh water are calcium and magnesium salts. Often, even less suffices. The behavior evidently depends upon the cation exchange properties of the clays, which favor adsorption of calcium and magnesium over sodium. Clays having sufficient adsorbed calcium and magnesium resist dispersion by water and consequent blocking of permeability. An allied phenomenon, the dependency of clay blocking on salinity contrast, is also reported. Abrupt change from highly saline to fresh water can cause blocking which may not occur if salinity is lowered slowly. A process related to osmosis is thought responsible for this behavior. Applications of findings to drilling, fracturing and water flooding are discussed. INTRODUCTION Many formations, when exposed to fresh water, can lose permeability through clay effects.',' For example, drilling-mud filtrate can cause oil permeability decreases, which persist long enough to interfere with drill-stem testing and well completion.3 Ultimate productivity may suffer when clay damage is severe, especially if drawdown pressures are low.' The injection pressures and the time required for water flooding can increase if clay blocking occurs. Earlier work indicates that clay blocking is caused by obstruction of flow channels by clays or other mineral fines dispersed by fresh water.'!" It is well known that increasing salt concentrations in water tends to prevent clay blocking. Also it is well established, although perhaps not as widely known, that the nature of the dissolved solids is also important. If, for instance, formation clays are exposed to calcium chloride solution and then exposed to weaker solutions of calcium chloride or distilled water, considerably less permeability damage results than if the clays had been exposed instead to sodium chloride solutions. The reasons for this behavior are: (1) clays are cation-exchange, or base-exchange, materials similar in this respect to zeolites or exchange resins, and (2) clays in the calcium form do not disperse easily in fresh water, whereas clays in the sodium form do. The base-exchange form of a clay is easily altered by flowing a solution through it. For example, a sodium clay can be changed to a calcium clay simply by passing a calcium chloride solution through the clay bed. There is general agreement that the reason calcium and magnesium clays do not disperse easily in fresh water is because the calcium ions do not ionize easily from the clay surfaces.' Sodium clays, however, are believed to allow the sodium ions to ionize from the clay particle surfaces. In fresh water, this allows the particle to accumulate a net negative electrical charge great enough for the particles to repel one another and, therefore, disperse more easily. The foregoing suggests that, even in the presence of a large excess of sodium, a relatively small ratio of divalent cation, such as calcium or magnesium, might serve to prevent clay dispersion. The divalent ion probably adsorbs to a disproportionately large extent, because of being adsorbed more tightly, with the result that the proportion of divalent cation on the exchange positions of the clay might then be great enough for the clays to resist dispersion. Consequently, an investigation was conducted to find how mixtures of salts in solution influence clay blocking. APPARATUS AND PROCEDURE Water permeability tests were conducted using conventional techniques. The equipment is illustrated schematically in Fig. 1. Flow rates of solutions driven through small core samples at known temperatures and pressures were measured. Regulated compressed air, usually at 10 to 15 psig, was used to drive the solutions. Core samples 0.75 in. in diameter and 1 in. long were used for the most part. Cores were saturated by evacuating and then admitting a de-aerated solution. Tight core samples were first saturated with carbon dioxide gas and then evacuated and saturated with the test solution. After saturation, 140 psig pressure was imposed for several hours. Cores were tested to insure absence of gas saturation by a Boyle's

Jan 1, 1965

By Orson Cutler, Shepard

THE OBJECT of this paper is twofold: (1) To analyze the forces that cause air bubbles to spread on mineral surfaces in the flotation process; and (2) To develop a rational expression that will serve as a criterion of the floatability of minerals, to the end that the efficiencies of various flotation reagents can be accurately compared. Heretofore, the subject of the spreading of air bubbles has been dismissed with the statement that the surfaces of minerals on which bubbles spread are water-repellent. Imperfect understanding of the forces involved has led to the use, hitherto, of various erroneous formulas for the calculation of the comparative effectiveness of flotation reagents.

Jan 1, 1932

By Hans Haalck

PRACTICAL or applied geophysics-as we designate the border region between physics and geophysics on one hand and practical geology on the other-has as its object the application of physical or geophysical methods of investigation to problems of practical geology. Its field of operation comprises all methods of physical measurement that are used in the problem of determining, from the geophysical influences of the subsoil that can be measured at the surface of the earth, the special characteristics of the association of strata, faults, etc., to detect the presence of deposits and to investigate underground structures. It therefore represents an aid, a physical method of research in practical geology, and is inseparably connected with geological studies; for this reason, it is also called geophysical prospecting. Formerly research methods of practical geology were based on observation exclusively: first, on the observation of the strata and formations at accessible tarts of the surface of the earth, especially in shafts, borings and mines if such were available; then on the observation of the tectonic conditions in so far as these were already known at places directly visible; and finally, by estimation of the importance of formations of the terrane. Later, there were added in special cases, analytical chemical crystallographical, petrographical and similar investigations of rock samples which were taken from the places under consideration. The knowledge thus obtained is of value and is expanded by hypotheses and constructions that are supported by geological theories of origin and by laws of the sequence of formations and rock systems, which are based on long experience.

Jan 1, 1928

By M. H. Rana, W. D. Bullock

A basic requirement in any geomechanical investigation is the establishment of the state of stress in the rock mass. So far, qualitative determinations have been more readily obtained than quantitative ones. This is due to the fact that in order to define stress magnitudes in a rock mass it is necessary to make various basic assumptions about the physical properties and characteristics of the rock itself. The assumptions are generally that the rock is an isotropic, homogeneous solid which will behave elastically under various conditions of applied load. These assumptions are not valid. Due to the foregoing factors, the present investigation was confined to a consideration of stress directions only. Within recent years, two methods of determining stress orientations in geologic materials have been used and have received some publicity in the technical press. These are the techniques of photoelasticity and petrofabrics. The technique of using reflected polarized light for observing strains on the faces of rock samples has been described by Emery.1,2 With this technique it is possible to measure relative strains in relaxation. Absolute strain magnitudes are not attainable without the use of questionable assumptions. However, directions of strains (and thus, stresses) can be determined accurately on a point basis or on a statistical basis over the complete area of the strain gage being used. Petrofabrics, according to Friedman,3 an important geological discipline which can provide knowledge on the state of stress associated with naturally deformed rocks. Even though textural and structural features span at least 15 orders of magnitude, from crystal lattices

Jan 1, 1972

By G. W. Traer

THE distillation of bituminous coals at what is commonly termed low temperature, and the quantities, nature and adaptabilities of the products have been the subject of considerable experimentation, during recent years. Fortunately, the earlier work in this country was done by men whose scientific training qualified them properly to record and interpret the results of-their experiments. The work of Prof. Parr, of the University of Illinois, is especially notable in this respect. Prof. Parr's work, added to that of English experimenters, demonstrated certain things to a degree which is generally regarded as convincing. They have proved that a caking bituminous coal, when subjected to a temperature of not more than 1000° F. (preferably somewhat less) will yield light tar having low specific gravity (about 1.06) and high value; also, that this yield, with a given coal, will depend upon the percentage of hydrocarbons in the coal, the maximum temperature used, and the promptness with which the distillate gases are removed. It is assumed that air is excluded from the retort, and that the coal is subjected to heat for a sufficient time to drive off all of the tarry hydrocarbons. The results attained in the first, or low-temperature stage of the Carbocoal process, recently described by C. T. Malcolmson, corroborate these general principles. It is the purpose of the writer to describe other work of a practical nature, directed toward the commercial adaptation of these principles, which was begun nearly two years ago; this investigation was assisted by A. J. Sayers, of the Link-Belt Co., and Carl Scholz.

Jan 9, 1918

By O. U. Bradley

THE methods of handling the oil output of the mid-continent fields are not unlike those practised in other oil fields of the United States, and it is not expected that this paper will present any entirely novel ideas. Some features of the practice of handling this oil may be of interest, however. WOODEN CAGING TANKS Practically all of the oil sold to pipe lines and other purchasing agencies throughout the Mid-continent field is gaged from wooden tanks. Steel gaging tanks are slowly coming into use, and are preferable in many ways-leakage and evaporation are reduced, and the strapping and recalculation of capacities are unnecessary. The wooden tanks are slightly coned to facilitate tightening the hoops. The-sizes in, common use are 250, 500, 800 and 1600 bbl. The number and the capacity of the gaging tanks upon any producing oil property depend upon its production, and the facilities for disposing of the output. The 1600-bbl. size was the most common in the Cushing field, particularly during the period of flush production. The tanks are distributed over the leased premises in groups of two, three, and four tanks each, and these are filled from flow tanks, or through direct pipe connections with the heads of the wells. Flow tanks are merely temporary reservoirs to facilitate the transfer of oil from the wells to the gaging tanks. They diminish fire risk,, and are considered indispensable on small producing properties where .water is pumped with the oil, as they permit the refuse and water to settle out before the production is run to the gaging tanks.

Jan 3, 1918

By William S. Hannan, H. Rush Spedden

Flotation may be defined as a process whereby mineral particles are concentrated by selective adhesion to air-liquid interfaces. The process involves attachment of desired mineral particles to air bubbles, and removal of the mineralized air bubbles from the surface of the pulp as a mineral concentrate. Problem Although great strides have been made in understanding the principles of flotation, one part of the process which has not been adequately explained is the mechanism by which selected mineral particles become attached to air bubbles. A glance at the froth of an operating flotation cell demonstrates adequately that use of proper reagents and conditions mill result in such attachments; but how such attachment takes place is not definitely known. A better knowledge of this factor might lead to improved flotation practice either through altered machine design or the application of scientific innovations. Direct observation of the behavior of mineral particles and bubbles in an operating cell does not appear promising because of the complexity of the system. For this reason, conclusions concerning the problem must be deduced from theoretical considerations or from observation of simplified systems designed to reproduce conditions thought to exist in an operating cell. Present Theories Two mechanisms have been recognized as fundamental in particle-bubble attachment: gas precipitation and direct encounter. It is a simple matter to demonstrate in the laboratory that attachment can be brought about by either mechanism. As to the relative importance of the two in a particular flotation system, however, there is a divergence of views. Taggart1 states, Under exceptional circumstances sufficient force and time to effect attachment may conjoin in an ore pulp undergoing agitation, and a preformed bubble adhere to a collector-coated mineral particle, but the occurrence is rare. . . . Pulp-body froth flotation effects selection in the body of a conditioned pulp by causing gas bubbles to precipitate from solution in the liquid phase preferentially at the surfaces of collector-coated particles, and to cling to these particles, Gaudin2 states that, within the pulp body of an agitation machine, attachment of mineral particles to air bubbles occurs as a consequence of contact between the two. This theory has been supported by theoretical reasoning and much circumstantial evidence. Perhaps the most interesting bit of evidence in favor Of this theory js the difficulty in the flotation of fines. If attach-

Jan 1, 1949

By Carl Lemke

SOME of the principal metallurgical difficulties en-countered in the differential flotation of lead-zinc-iron sulfide ores arise from the following causes: The oxidized, or partly-oxidized, condition of one or more of the minerals ; impurities in the minerals them-selves; composition and character of the gangue miner-als; soluble salts in the ore; and unfavorable metal ratios. In many of the ores received at a custom mill there are present appreciable amounts of oxidized' or partly-oxidized minerals, although the ores may be substantially sulfides. Often the ores are not oxidized at all when received but on account of operating condi-tions at the mill it is necessary to stock them for several months before they can be milled, and considerable oxi-dation takes place while they are lying in stock. In most ores received at Midvale, when oxidation is pres-ent, the lead and iron sulfides have been more affected than the zinc sulfide, but with some ores the zinc mineral has also become partly oxidized. Some ores, such as those taken from old mine-dumps or from old stopes, may show very little total oxidation, but the greater part of the valuable minerals has been sufficiently acted upon by oxidation to make the minerals very difficult to float. Ores of this character are among the most difficult the flotation operator has to contend with, be-cause the galena, sphalerite, and pyrite are all sluggish in their behavior in the flotation cells. Only a part of the lead mineral will float in the lead circuit. The re-mainder will lag badly and tend to come up with the zinc or, if badly oxidized, will go -through all the flota-tion circuits into the tailing. The zinc mineral, if it has also been affected by oxidation, will act in a man-ner similar to the lead mineral. A hard pull will be required to float a reasonable percentage of it, and this is likely to bring up so much pyrite that it will be difficult to make a zinc concentrate of commercial grade. If it happens that the zinc mineral has not been no-ticeably affected by oxidation it will tend to float in the lead circuit because a hard pull is also required in that circuit in order to bring up the sluggish galena. When only a fraction of the sulfide minerals has become partly altered, or completely oxidized mineral is present in relatively small quantity, it is usually possible to make reasonably clean concentrates of all three sulfides, that is, lead, zinc and iron concentrates. Most of the oxi-dized and semi-oxidized minerals will go into the tailing and the losses will be proportional to the oxidation.

Jan 4, 1927

By C. H. Hitchcock

The puiblication by the Institute of a small geological map of the United States calls for an explanation of its peculiarities. The title intimates that it is intended "to illustrate the schemes of coloration and nomenclature recommended by the International Geological Congress." By way of further explanation it is said to be "based, by permission of the Director of the United States Geological Survey, upon the map published in his Fifth Annual Report, the portions not colored in that map being here supplied from other sources." The map referred to was prepared by W. J. McGee, and in the text of the report containing it he has given a list of the authorities employed in the compilation. The scheme of coloration used for the map was the one proposed by the Director, in the Seeond Annual Report, for the publications of the United States Geological Survey, which differed materially from those employed by the older American geologists. Because of the increasing diversity in the particular colors employed to represent rocks by geologists in different countries, and of the existence of very dissimilar schemes of nomenclature, it seemed best to the American Association for the Advancement of Science, at its Buffalo meeting in 1876, to appoint an international committee of geologists, who should consult together, and, if feasible, to call an International Congress to discuss these subjects. The proposition met with favor, and the meeting was called. The first session was held at Paris, in 1878, when geologists were present from twenty different countries. Once organized, the Congress has perpetuated itself, enacting regulations for its conduct, choosing the French language for its medium of communication, and arranging for the compilation of a geological map of Europe upon which the perfected schemes of coloration and nomenclature will be delineated. The American Association maintains a standing committee to represent it at the international sessions, and to report their proceedings. Sixteen countries were represented at the second Congress, at Bologna;

Jan 1, 1887

By J. W. Downey, M. V. Nevitt

The phase boundaries for the 950" isothermal sections in the ternary systems Zr-Co-0 and `Zr-Ni-0 have been determined for the composition range from 50 to 100 at. pct Zr. The two systems show very similar phase relations, having no extensive solid solution phase fields. Each contains a ternary phase. These phases are apparently isostructural, but their structure has not been determined. Some aspects of the phase relations are discussed in terms of the alloying behavior of transition metals. THE work described in this paper is the outgrowth of a recent study of the occurrence of phases having the Ti2Ni-type structure (structure-type E9,) in certain ternary systems involving Ti, Zr, or Hf with another transition metal and O.", In the Zr-CO-0 and Zr-Ni-0 systems no Ti2Ni-type phases were found to occur. However, there are several interesting aspects of the phase relations in the two systems which have significance from the point of view of the alloying behavior of transition metals. The results of this investigation may also have some importance in studies of the oxidation of Zr-Co and Zr-Ni alloys. In both the Zr-Co-0 and Zr-Ni-0 systems only the 950" isothermal sections were investigated and, as a further restriction, the study was limited to the composition range from 50 to 100 at. pct Zr. A tentative Zr-Co binary diagram has been published by Larsen, Williams, and Pehin. In the composition range pertinent to the present work they report a eutectic at 980°C and 75.9 at. pct Zr, the products of which are the terminal solid solution based on /3 Zr and the compound Zr2Co, and a eutectic at 1080" and 64.8 at. pct Zr whose products are Zr,Co and ZrCo. The solid solution based on /3 Zr is shown to decompose eutectoidally at 826°C into a Zr and Zr2Co. The limits of solubility of Co in a and /3 Zr have not been established. The structure of Zr2Co is not identified in the publication just cited. Dwight has reported that ZrCo has the CsC1-type strcture. The Zr-rich portion of the Zr-Ni diagram has been determined by Hayes, Roberson, and Paasche." The phase relations are very similar to those of the ZrCo system. A eutectic reaction whose products are /3 Zr containing 2.9 at. pct Ni and Zr,Ni occurs at 961°c, and a eutectic between Zr,Ni and ZrNi is found at 985". The solid solution based on /3 Zr decomposes eutectoidally at 808°C. The solubility of Ni in a Zr is not known accurately but is believed to be very small. Smith, Kirkpatrick, Bailey, and Williams7 have found that Zr2Ni has a tetragonal structure of the A1,Cu-type and that ZrNi is orthorhombic. Domagala and McPherson8 have published a constitution diagram for the system Zr-ZrO,. At 950" their diagram indicates that the solid solution of 0 in 0 Zr is stable from 0 to 0.5 at. pct while the phase field of 0 in a Zr extends from 6 to 29 at. pct. These solubility limits were adopted in the present study and no binary Zr-0 alloys were made. No previous data on the phase diagrams of the ternary systems are known to exist. EXPERIMENTAL PROCEDURE The experimental details involved in the preparation of alloys in this laboratory by arc melting have been described in several previous papers"3 and they will not be repeated here. Information concerning the purity of the metals used is given in Table I. Oxygen was added in the form of reagent grade ZrO,. All of the cast specimens in both alloy systems were annealed in air-atmosphere tube furnaces at 950 3' for 72 hr and water quenched. The specimens were protected from oxidation by wrapping them in Mo foil and sealing them in quartz tubes that had been evacuated at room temperature to a pressure of 1 x 10B mm of Hg. The phase boundaries were determined by metallography, and identification of the phases was accomplished primarily by X-ray diffraction methods which employed a powder camera having a diameter of 114.6 mm. The diffraction techniques which are in use in this laboratory have been previously described.' An etchant that proved satisfactory for most of the alloys consisted of 5 pct by vol of AgNO

Jan 1, 1962

By C. F. Allen, G. B. Walker

K. F. TROMP*—In dealing with the question of the most suitable kind of solid media for heavy density suspension processes Walker and Allen point out that the particle size of the solid media should not be taken too fine, as the viscosity increases with the area of the solid media and a low viscosity is essential lor high tonnage and accurate separation. A coarser particle size of the solid media will, in their opinion, of necessity give rise to a differential density in the bath (higher gravity at the bottom of the bath than at the top) but they advocate acceptance of the differential density rather than a higher viscosity. Though I fully agree with the choice the authors have made, I cannot subscribe to their view that only by accepting a differential density in the bath a coarse particle size of the solid media can be used. There certainly is another alternative: stronger agitation. Applying sufficiently strong vertical currents, a uniform gravity can be obtained quite well in a suspension of a coarse solid media. Of course, this is not a very attractive solution, for it means a degradation of the true gravity separation and a step backwards to hydraulic classification, which makes the washing dependent on size and shape of the particles. However, to a greater or lesser extent, this is what actually takes place in all the heavy density suspension processes relying on a uniform gravity in the bath. The so-called "stable" suspension processes make no exception. They all "stabilize" their suspensions by introducing or creating vertical currents, be it upwards or downwards or both, be it by hydraulic or by mechanical means. In fact, there is no such thing as a "stable" suspension in gravity separation, as the very reason for the use of suspensions in this field is the property that the solid media is able to settle and so facilitate the recovery. I have been enlarging on this point because the characteristics of the various processes can only be well understood and viewed from the same angle (from Bar-voys up to Chance) when the fact is recognized that mechanical or hydraulic agitation is a condition sine qua non for obtaining a uniform density from top to bottom in a suspension. Is a Cone-slraped Vessel Essenlial? Of the two alternatives for getting a low viscosity Walker and Allen have preferred correctly the sacrifice of uniform gravity in the bath instead of increasing further their vertical current arid agitation. The resulting differential density of the bath brings the problem of bow to prevent accumulation of intermediate gravity products in the bath, an accumulation which, if not prevented, would ultimately plug their cone. According to the authors an open-top cone combined with a downdraft current of the bath liquid would he the only suitable way to cope with such suspensions and they assume as a fact that "in any vessel other than a cone, such a differential density could not be tolerated." My experience is quilt: different. In my process, which has been in successful operation for more than a decade, differ-ential density of the suspension is applied ranging from values below 0.1 up to differentials above 0.5, according to the prevailing requirements of the individual plant. In this process, which is charac-terized by the use of horizontal currents in a suspension of differential density, the form of the vessel is of secondary importance and different types are in operation. It so happens that none of these are in the, form of a cone. The fact that 24 washboxes on my process have been installed and 12 others are under construction may constitute sufficient proof against the opinion that only a cone-shaped separator would be suited for differential density separation. Horizontal Currents in Differentia1 Den-sity Sepparation I myself have some doubts as to the suitability of a cone with downdraft for dealing with differential density (or, for that matter, any other washbox relying on vertical currents for removing the intermediate gravity products). It ap-pears to me that it is restricted to feed of small size only and even then with watch-fulness. If we take, for example, a piece of 2 in., the draft necessary to pull such a piece down to a zone wherein the den-sity of the suspension is, say, 0.03 higher, is quite considerable. For a suspension of, say, 1.6 sp gr the downdraft will have to be in the region of 3 in. per second. Unfortunately. most of the differential in density is in the part immediately below the reach of the top current which transports the floats. Consequently, we need the downdraft where we like it least: in the upper part of the cone. This entails the risk that light float particles are carried away with the downward current. This current of, say again, 3 in. per second would carry particles up to 1.3 sp gr and 3/8 in. size into the 1.6 gravity zone. This is prohibitive. It is also prohibitive because a downdraft of 3 in. per second in the upper part of the cone would require a tremendous circulation of medium. IIalf way up a 20 ft diam cone, a downdraft of 3 in. per second would correspond with 8500 gpm. With the downward current following the way of least resistance, the strength of the downdraft will not be exactly the same at different places of a cross area. If, as I anticipate, the center of the cone is favored, the strength of the downdraft will fall below the critical value near the

Jan 1, 1950

By Olof Löfgren

PART 1 INTRODUCTION All modern pelletizing plants are equipped with either the drum or the disc circuits. Choice of one or the other circuit is not simple and it is desirable to establish a firm basis for such a task. For a meaningful and a fair comparison it is necessary to have the two systems working in parallel in the same plant with the same concentrate under the same supervision. Furthermore, the comparison has to be based on a defined green ball quality and size distribution. BALLING CIRCUITS The LKAB straight grate plant at Malmberget, Sweden, was started up in Septenber 1973. It was designed for a 2.5 Mton annual capacity and was equipped with five balling drum circuits. During the first year of operation it was found that the induration plant had the potential for a higher capacity which required increased balling capacity. For this purpose it was decided to install a balling disc circuit complete with a roll screen. The reasons for selecting a disc were space limitations and LKAB's desire to gather experience on balling disc circuits. The disc circuit was started up in 1975 and was run in parallel with the balling drums in the same plant and with the same raw material and under the same operating personnel. The necessary conditions for a comparison were thereby fulfilled. The data for the size distribution and quality of the green balls were obtained on random sampling during one year of operation, so that all the variations which appear in a commercial plant are covered.

Jan 1, 1977

By Charles S. Robinson

The Henderson ore body is east of the Continental Divide in the Front Range of the Colorado Rocky Mountains, about 80 km (50 miles) west of Denver. The ore body is being developed for mining by workings that extend more than 1100 m (3500 ft) below the topographic surface. During construction of the mine workings, ground water in fractures in cystalline rock has been encountered. From 1969 to 1973, Charles S. Robinson & Associates, Inc., in cooperation with the engineering and geologic staffs of the Climax Molybdenum Company, a division of Amax Inc., studied the ground water geology of the Henderson mine development area. Detailed geologic record( of the Henderson mine were available as a result of the exploration, evaluation and development of the mine. Records of the flow, chemical composition and temperature of the ground water at and near the surface, from the entire mine, from portions of the mine, and from exploration holes drilled in the mine, were kept as the mine was developed. Where possible, ground water pressures in drill holes and changes in pressure with time, were recorded. The geologic, hydrologic and chemical data were correlated. The following conclusions were drawn from the correlations: The ground water in the Henderson mine occurs in fractures in Precambrian igneous and metasedimentary rock and in a series of Tertiary intrusive rocks. Two zones of ground water were recognized; an active zone, in which the fracture systems are recharged and discharged annually into the surface water system, and a passive zone, in which the fractures were filled with water in the geologic past. Discharge from the passive zone is through mine workings that intersect the fracture systems. Discharge from a fracture or fracture system is initially high but decreases with time. The rate of decrease in flow (or pressure) is exponential. By measuring the change in flow with time, it is possible to calculate the amount of flow at some given period of time in the future. Based on changes in rate of flow and pressure, and the geology, and assuming rates of mining of the ore, it will be possible to predict the volumes of water that will have to be handled during the life of the mine and the area around the mine that will be drained by the mining operation.

Jan 1, 1979

By C. Erb Wuensch

The Eagle mine is situated in the Kerber Creek mining district, Bonanza, Saguache County, Colo. The climate and topography of this district arc similar to those of mining camps of the Rocky Mountain region that lie 9000 to 12,000 ft. above sea level. The district is at the northeasterly edge of the San Juan volcanic region, in which successive Tertiary lavas have built up a high plateau resting upon earlier sedimentary formations, or the underlying pre-Cambrian complex. The latter was exposed in places by erosion previous to the eruptions. In the Bonanza district, proper, only volcanic formations, andesites and latites, are found. Dr. H. B. Patton,1 in his survey of the district, discriminates between several varieties of lavas and maps these as distinct flows. They are local variations within the same lava and it is impossible to determine any distinct line of demarkation between them. Structurally they are members of the same flow. There are three general types of vein occurrences: 1. Lead-zinc-copper-silver-gold veins in well-defined fissures with a quartz gangue; ill these, the various sulfides show a zonal arrangement. 2. Massive gray copper ores high in silver, in irregular fractures in the form of small lenses and pockets, in which little or no quartz is found. 3. Manganiferous quartz veins very low in silver and gold at the surface which, with depth, become important silver veins containing subordinate amounts of gold. These veins have a quartz gangue with an abundance of Phodochrosite. The silver is associated with small amounts of sphalerite, galena, and pyrite; fluorite also is present. The Eagle is the only mine that has been developed in the manganiferous quartz type of vein. It was discovered ill the fall of 1582, but little more than assessment work was done on the property for a number of

Jan 1, 1923

By C. Erb Wuensch

The Eagle mine is situated in the Kerber Creek mining district, Bonanza, Saguache County, Colo. The climate and topography of this district arc similar to those of mining camps of the Rocky Mountain region that lie 9000 to 12,000 ft. above sea level. The district is at the northeasterly edge of the San Juan volcanic region, in which successive Tertiary lavas have built up a high plateau resting upon earlier sedimentary formations, or the underlying pre-Cambrian complex. The latter was exposed in places by erosion previous to the eruptions. In the Bonanza district, proper, only volcanic formations, andesites and latites, are found. Dr. H. B. Patton,1 in his survey of the district, discriminates between several varieties of lavas and maps these as distinct flows. They are local variations within the same lava and it is impossible to determine any distinct line of demarkation between them. Structurally they are members of the same flow. There are three general types of vein occurrences: 1. Lead-zinc-copper-silver-gold veins in well-defined fissures with a quartz gangue; ill these, the various sulfides show a zonal arrangement. 2. Massive gray copper ores high in silver, in irregular fractures in the form of small lenses and pockets, in which little or no quartz is found. 3. Manganiferous quartz veins very low in silver and gold at the surface which, with depth, become important silver veins containing subordinate amounts of gold. These veins have a quartz gangue with an abundance of Phodochrosite. The silver is associated with small amounts of sphalerite, galena, and pyrite; fluorite also is present. The Eagle is the only mine that has been developed in the manganiferous quartz type of vein. It was discovered ill the fall of 1582, but little more than assessment work was done on the property for a number of

Jan 1, 1923