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By Y. L. Yao

A scale based on existing data for the mutual solid solubilities of metals in binary systems has been compiled. This scale is useful for estimating the relative magnitude of two solubilities, provided that these two metals do not form a continuous series of solid solutions. In his classic work on the theory of metallic solid solutions, Hume-Rothery proposed that, other things being equal, a metal of lower valency should be regarded as more likely to dissolve one of higher valency than vice versa. He called this the "relative valency effect". Later he found that the application of this general principle was limited to the three univalent metals: copper, silver, and gold. In dealing with alloys of these metals with metals of higher valency, Hume-Rothery stated, it is usually found that the solid solution of the univalent metal is of the greater extent.&apos; The question of whether there is a systematic trend in comparing the relative magnitude of mutual solubilities, if valency is not considered a criterion, naturally arises. The present paper proposes a "mutual solid solubility" scale on an empirical basis. The order of its arrangement is determined by the relative magnitude of mutual solid solubilities. Some applications of and inferences from this scale are given. ORIGIN AND SCOPE OF THE SCALE An extensive survey of over 400 binary phase diagrams shows that, with certain exceptions and within certain limitations, metals can be arranged in the following order: Na Zn Cd Ga Bi Ge Sb As Hg Sn Si Mg Li Ba In Tl Pb Al Ca Be Mn Cr Re W Mo Cu V Ta Fe Ru Cb Co Ti Hf Ni Os Zr Ir Pt Au U Rh Ce Pd Ag Th so that a metal higher on the scale tends to have a higher solubility in a metal lower on the scale than vice versa. some experimental solubility data are given in Table I. These data, unless otherwise specified, are taken from Hansen and Anderko.6 Throughout this paper, the term "solubility of A in B" is taken to mean the maximum solid solubility of A in B in atomic percent, while the maximum solid solubility of B in A in atomic percent is called "reciprocal solubility". The exceptions found in the above-mentioned survey are: Al-Ag system, 20.34 at. pct Al in Ag, 23.8 Ag in Al; Mg-Pb system, 5.9 Mg in Pb, 7.75 Pb in Mg; As-Sn system, vanishingly small amount of As in Sn, a large As primary solid solution; Cd-Hg system, Cd in Hg <Hg in Cd; Mg-T1 system, 5(?) Mg in ßT1, 15.4 T1 in Mg; W-Ti system, -21 W in ßTi, -25 Ti in W; Zr-Ag system, probably small amount of Zr in Ag, 20 Ag in ßZr.7 Considering the large number of examples, the exceptions are few. It is remarkable that metals may be so arranged without considering other factors such as size, crystal structure, electronic structure, and so forth. A limitation to the use of the scale is the fact that it cannot be tested for two metals forming a continuous series of solid solutions. It is interesting to point out that when the continuous solid solutions have a miscibility gap the critical composition is

Jan 1, 1961

By Clarence Fenner

THE manufacture of optical glass is a process that demands careful regulation and control at all stages in order that satisfactory results may be obtained. The product, to serve its purpose, must meet stringent requirements, which can be assured only by careful procedure in manufacture. During the greater part of the time that a pot of glass is in the furnace, temperatures should be kept within certain rather narrow limits; a departure on either side is likely to be detrimental to the glass and may result in total loss. If the temperature during melting and fining be low, the melt is likely not to fine properly and the glass will contain quantities of bubbles, or "seed," or it may become milky and unfit for use; too high a temperature, on the other hand, is severe on the pot and may cause it to leak or cast stones, or the increased solution of pot material in the melt may acid to the color of the glass and decrease its transmission. Moreover, variations in the working temperature will mean variations in the amount of selective volatilization and, consequently, variations in optical properties from pot to pot. Furthermore, in the closing stages of furnace treatment, the melt is cooled until a certain degree of stiffness is attained, when the pot is withdrawn. The quality of the glass-its freedom from striae and bubbles-will depend in large measure on whether the temperature to which cooling has been carried is suitable. For each type of glass there is a narrowly restricted range of temperature to which each pot of the given type should be cooled before withdrawal. A quick and reliable method of measuring temperatures is, therefore, of the first importance. In the optical-glass work conducted by the staff of the Geophysical Laboratory during the period of the war, much attention was given to the clatter of determining what methods would meet the requirements. This article will deal with these investigations and with the application of the results to actual practice at various plants. At the. time that the work of the Geophysical Laboratory was begun at the Bausch & Lomb plant, each melting furnace was equipped with

Jan 7, 1919

By W. G. Cornwell, R. J. Hisshion

The development of a process for the treatment of telluride concentrates at Emperor Gold Mining Co. Vatukoula, is discussed. The concentrate is produced by flotation in cyanide solution immediately after milling. Two stages of cleaning are employed and a high-grade concentrate is produced usually containing more than 50% of the precious metal. The process developed in the first instance involved batch roasting followed by batch leaching in strong cyanide solution, recovering gold and silver only. The procedure currently employed is chemical oxidation of the tellurides using hypochlorite as the oxidant in a basic solution of a caustic soda and sodium carbonate. After oxidation the gold and silver are recovered by cyanidation. The residue is then leached with sodium sulfide and elemental tellurium precipitated with sodium sulfite.

Jan 1, 1977

By B. B. Zavoico

Considerable progress has been made during the past year throughout the Russian petroleum industry. Perhaps the most remarkable achievement is the execution of the programs set out by the Central Planning Bureau of the Department of Commerce. These programs have been increased twice during the past operating year, necessitating drilling the richest reserves, instead of developing gradually as originally planned. The fulfillment of the set-out programs during the past few years makes therefore the present five-year plan of considerable importance to the international oil statisticians in approximating actual supply conditions up till 1933. The production of all Russian fields increased by 14,200,000 bbl. as compared with the 1927-1928 operating year, while the next year&apos;s program anticipates a further increase of 15,700,000 barrels. It appears therefore that production for 1932-33 will total 187,000,000 bbl., or approximately double that of the operating year just closed. It is also evident that the old fields are counted upon to produce only about 67 per cent. of the total, the new fields, not yet discovered, to furnish the balance of 33 per cent. The Soviet oil leaders therefore are hoping to have new fields discovered and developed by 1932-33. However, as in the past wildcatting

Jan 1, 1930

By I. F. Jackson, H. L. Hartman

Hard-metal inserts have received considerable attention in the mining industry recently for a variety of excavating and penetrating purposes. Their use in percussive drilling and in coal cutting machines is well known, but attempts to utilize them in cutting materials such as dimension stone have been discouraging because of excessive tool wear and failure. Particular attention is given to those properties of hard-metal inserts that affect their resistance to wear. A consideration of the actual wear mechanism shows the importance of correct mounting of the inserts and of the selection of suitably powered driving motor so as to achieve minimum tool wear and maximum tool life. Comparisons are made between the performances of types of hard-metal inserts, relating their inherent properties with results obtained in laboratory tests. As part of a broad program to improve the quarrying and processing of industrial minerals, The Pennsylvania State University has been investigating the machinability of slate under laboratory and field conditions. It should be emphasized that the results of the research presented in this paper are also applicable to other natural structural materials, and particularly to the more workable ones such as limestone and sandstone. Improvements which accrue in cutting and sawing should prove of benefit to all the dimension stone industry. Further, it may be pointed out that the results reported here are applicable to rotary drilling (with drag bits) as well as to cutting and sawing of rock. INVESTIGATIONS IN RELATED FIELDS The investigation was initiated with an extensive survey of available literature related to metal cutting and to rotary drilling. The following similar features between metal cutting and slate cutting became evident: 1) Hard-metal inserts are widely used as a cutting tool in both cases. 2) The forces acting on the tool may be resolved into normal and tangential components. 3) Rate of penetration and tool wear are important criteria in each case. On the other hand, important differences also exist: 1) Most metals, exhibit plastic behavior, while slate (and most rock) is a brittle material under normal conditions. 2) In metal cutting the component of force acting parallel to the surface of the workpiece is considerably greater than the force holding the tool against the workpiece. 111 slate cutting, this situation is reversed. Similarities between drag-bit rotary drilling and slate cutting are as follows: 1) In both casts, a tool, usually of the hard-metal insert type, is used to penetrate a brittle material. 2) The drilling forces and related variables, such as rotation speed, are similar. 3) Chip formation in each case is essentially the same. 4) The shape of the tool is similar in rotary drilling and slate cutting. Important differences are also apparent: 1) The objective of drilling is to produce a directed hole, while in cutting it is to form a kerf. In core drilling, however, a kerf is also produced. 2) The horizonta1 component of force in rotary drilling decreases from the center to the outside of the tool, whereas in slate cutting the component is almost uniformly distributed across the width of the tool. 3) The power absorbed in the drill rod is greater in rotary drilling. 4) The clogging action of chips, if excessive power is applied to the tool and if flushing is insufficient, is more serious in rotary drilling. Because of the striking similarities between metal cutting and slate cutting, and between rotary drilling and slate cutting, it was considered that the findings of investigators in those fields would serve as a guide for experimental studies of slate cutting. The following is thus devoted to a discussion of those aspects of metal cutting and rotary drilling pertinent to the present investigations.

Jan 1, 1962

By R. V. Colligan

[CONTENTS PACE Educating and Training Economic Geologists of the Future. By C. H. BEHRE, JR. (TP 2278, Min. Tech., Nov. 1948. Discussions by R. V. COLLIGAN and EVAN JUST) ....... I Mercury Industry in Italy. By EDWIN B. ECKEL. (TP 2292, Min. Tech., Jan. 1948. Discussion .............................. by C. N. SCHUETTE) 3 Chert in the Kingsport Formation at Mascot, Tennessee. By ARTHUR T. ALLEN. (TP 2299, ............... Min. Tech., Jan. 1948. Discussion by M. M. BUTLER) 5 Wall Rock Alteration at Butte, Montana. By RENO H. SALES and CHARLES MEYER. (TP 2400, Min. Tech., May 1948. Djscussions by C. D. HULIN, W. D. JOHNSTON, JR., and L. C. ................................... GRATON) 5] Educating and Training Economic Geologists of the Future R. V. COLLIGAN*-I can best illustrate my opinions by drafting another five year plan (Table 2). This plan is set up following the same stipulations outlined by Dr. Behre, namely: (I) the student is preparing himself for commercial work as a mining geologist; (2) he is attending an institution with a sufficiently broad curriculum (that is, engineering school and mining school as well as liberal arts college) to furnish the courses listed; and (3) he is not planning to continue his studies through to a doctor&apos;s degree before going into commercial work. A comparison of my study plan (Table 2) and that submitted by Dr. Behre (Table I) will at once point up the basic similarity, due to the obvious fact that there are so many essential courses which must be included in any outline of study. However, a more detailed analysis will show up certain differences, which, in fact, are only certain refinements on Dr. Behre&apos;s program. These I plan to discuss in order of their importance. The first and most important change is the addition of 12 hr of optional subjects, making a total of 24 hr of optional subjects as against a total of 12 hr under Dr. Behre&apos;s schedule. This of course entails the elimination of certain courses, which I shall discuss later. However, I wish to make it clear that I suggest eliminating these courses not because I feel that they are unnecessary, but rather because I feel the optional courses are more necessary to the complete education of the individual. I appreciate that Dr. Behre recognizes the importance of the cultural side of education, but I take issue with his thesis that the student will get it without credit and in his spare time. I do not think that the average college student, and certainly not the college freshman, is mature enough to know what he needs and where to get it in his spare time. I think it must be "spoon-fed"; he must be oriented through specific courses. University life (or should I say "college life") is too full of athletics, fraternity activities, dances, "bull sessions," and countless other enjoyable distractions, all of which contribute to the "full man." I fail to see how the average young American male can possibly sandwich in a necessary complement of "cultural activities" in his spare time. Since these latter activities do not fall within the pattern set by the "group," and show less promise of immediate return in enjoyment, or increased social status on the campus, they are bound to suffer in competition with the more popular, "group" activities. No doubt much of the criticism levelled against arts colleges, namely, that the cultural courses are useless, is well taken, for the culture

Jan 1, 1947

By E. P. Barrett

THE high-frequency laboratory induction furnace with a rotating liquid crucible enables research workers to conduct certain investigations heretofore very difficult or impossible to realize because vessels are not obtainable that are capable of resisting the physical conditions or the chemical actions to which they are subjected. Applications for patents covering commercial uses of centrifugal liquid crucibles were filed in the United States in 1919,1 in France in 1925, in the United States and Germany in 1926,2 and in France in 1927.3 In 1928, Schuette and Maier,4 of the Bureau of Mines, reported the construction of a whirling table beneath a high-frequency induction furnace. SHAPE AND SIZE OF CENTRIFUGAL LIQUID CRUCIBLES When a vessel containing a liquid is rotated, the inner surface of the liquid takes the shape f a paraboloid under the simultaneous action of centrifugal force and gravity. The internal dimensions of the paraboloid rotating liquid crucible are governed by the diameter of the container and its speed of rotation. Melted Wood&apos;s metal was poured into cylinders 2 ½ in. in diameter, which were rotated at 180, 300, and 468 r.p.m. When the metal was solid, a slurry of plaster of Paris was added, and rotation continued until the plaster had set. Fig. 1, a photograph of sections f the cylinders, shows the effect f speed f rotation of the containers upon the shape f the inner surface f the rotating liquid crucibles.

Jan 1, 1938

By James E. Lawver, James L. Wright

This paper describes the design of a cell used to measure the electrical conductivity, or the reciprocal resistivity, of granular materials. It also establishes a quantitative relationship between the electrical conductivity and the electrical separation of selected mineral samples. It is estimated&apos; that the free world produces about 13 million tons of mineral concentrates a year by electrostatic or electrodynamic methods. At least 95% of these concentrates are produced by corona discharge type machines that separate minerals by exploiting the differences in their electrical conductivity. But, what is meant by the electrical conductivity of a mineral? How large a difference in the electrical conductivity of two mineral species is necessary to effect a separation? Just what is the role of conductivity in electrical separations with regard to capacity and selectivity? There is a considerable amount of information in the literature on both the mechanisms of conduction and the values of the electrical conductivity of pure single-crystal mineral specimens. In addition, some insight into the role of mineral conductivity can be obtained by referring to a Bureau of Mines publication&apos; in which 95 minerals have been grouped as conductors or insulators as a function of temperature. The classification was made on the basis of the percent of weight that reported as "conductors" in an electrical separator. But, as is often the case in the mineral industry, practical application leads theory — and there is little useful information in the literature giving any kind of quantitative relationship between electrical conductivity and electrical separations. The problem is a bit complex because electrical conductivity per se — which can be rather easily measured on large, single grains — is not sufficiently informative to permit quantitative predictions of the separability of the mineral system. Practical "high-tension"* separations are made at such feed rates that the band of minerals on the rotor is multilayered in thickness. Thus, the effective conductivities of minerals as seen by a high-tension machine include particle-to-particle contact resistance, which is often a controlling factor in making a separation. This is particularly true when the mineral grains are coated with slime or with a dielectric surface film. From a high-tension separation viewpoint, one is actually concerned with the time required for corona-charged grains to lose enough charge so that the centrifugal force acting on the particles exceeds the image force holding the grains to the rotor. This calculation requires a knowledge of the effective mineral conductivity s. (The conductivity of the metal rotor is sufficiently greater than that of the minerals so that it need not be considered in charge decay calculations.) The charge density at time t can be approximated by the relaxation equation.3 where t 5 charge density at time t r, - charge density when t = 0 cr e total electrical conductivity £ = permittivity The time required for the charge density to fall to l/e of its initial value is called the relaxation time and is numerically equal to €/n. AS defined here, u is the conductivity of an element of homogeneous grains making contact with each other and with a grounded rotor. This paper deals with the design of a conductivity cell used to measure a, or its reciprocal p, the electrical resistivity. CELL DESIGN Initial test work was performed with a cell recommended by ASTM.4 Since the reproducibility with the ASTM cell was not satisfactory, it was decided to

Jan 1, 1970

By A. M. Gaudin, T. P. Meloy

This paper presents the theoretical derivation of the distribution equation for single fracture. The equation is shown to accord with experiment. Several empirical size-distribution equations have been proposed to describe the size of broken materials. Among them are the Gaudin-Schuhmann equation and the Rosin-Rammler equation.3*4 The Gaudin-Schuhmann equation relates the relative fraction of undersize to relative size —. In this relationship Mo is the total weight of crushed sample, M(x) the weight of undersize contained, x the size considered, K a quantity called the size modulus, which together with the slope parameter, m, characterizes the product. The slope parameter is usually close to unity. The Rosin-Rammler equation relates the same relative fraction of undersize to the relative size modulus by an equation of different form In this relationship, e is the base of natural logarithms. In the fine size-range when m is unity both equations give Gilvarry and Berstrom have sought a size distribution equation having a sound theoretical basis. They have come to an equation taking into account the effect of volume, surface and edge flaws in fragmentation. If the effect of the volume and surface flaws is neglected, the equation taking only edge flaws into account has the form of the Rosin-Rammler equation. In the present paper, a theoretical size-distribution

Jan 1, 1962

By S. C. Termes, R. L. Wilfong

As part of an effort to provide basic data on the fundamental scientific and engineering principles of minerals beneficiation, the Bureau of Mines is conducting research on the flocculation of mineral fines. This paper presents results of studies using cross-linked starches containing carboxyl, diethanolamine, iminodiacetic acid, and xanthate groups to flocculate hematite, goethite, chromite, manganite, pyrolusite, cuprite, and cassiterite fines. The carboxyl and xanthate derivatives flocculated all minerals except cassiterite; the latter was flocculated by only the diethanolamine derivative. The imlnodiacetic acid derivative flocculated hematite, goethite, chromite, cuprite, and pyrolusite fines. Zeta potential measurements were made to help define the reaction mechanism responsible for flocculation. These measurements indicate that electrostatic attraction probably is not involved, except possibly in the case of the diethanolamine derivative. The separation of hematite from quartz by selective flocculation with chelating crosslinked starches under two pH conditions and with two dispersing agents is described. Best recoveries and grades were found when either the carboxyl or xanthate derivatives was added at the natural pH of the pulp in the absence of a dispersing agent.

Jan 1, 1984

By Michael P. Richardson

INTRODUCTION This paper is intended to be a summation of the state-of-the-art i n draw theory and draw- point spacing. Knowledge of this very important factor in the successful design and operation of a block caving mine is scarce and nonconclusive. It is hoped that the presentation of this paper will stimulate interest and discussion which will lead to a stronger understanding of these a1 1 important factors. Please note that block caving as used here- in refers to block, panel, and mass caving systems in general, not just to the specific system of block caving where discrete blocks of ore are prepared and caved as a unit. DRAW THEORY The knowledge of draw theory as related to the practice of block caving mines is, unfortunately, very limited. In recent years much work in draw theory has been done in respect to sublevel caving systems and an understanding of draw mechanics relating to sublevel caving seems to be emerging. This work is certainly helpful to those of us interested in block caving but the question of "what goes on up above" still hounds us since we are more interested in the region of draw which begins just above the area where sublevel caving interest ends. Herein is presented a brief summary of draw theory with an attempt to look at the factors which can help our understanding of the area of draw influence in block caving mines. Nature of Gravity Flow An understanding of the flow of granular material (rock, sand, grain, or prill as examples) is the first step toward understanding block caving draw. If we take a supported column of granular material and allow gravity flow through an aperture at the bottom of the column, an ellipsoidal shaped zone of disturbance of the in-place material will form and grow with extraction of material through the aperture. The volume of this zone of disturbance or loosening is about 15 times the volume of material extracted at any given time (Kvapil, 1980). Figure 1 shows the development over time of the zone of disturbance. The ellipsoid of disturbance represents a future ellipsoid of extraction which will equate to the volume of materia1 extracted by that future time. Extraction involves the movement of the particles located vertically over the drawhole directly downward while material outside this direct vertical volume moves radially inward and down toward the drawpoint as shown in Figure 2a. Figure 2b shows the result of this motion on originally horizontal strata within the ore column. Increased draw increases the eccentricity of the ellipsoidal volume or, in other words, the ratio of the height over the width of the disturbed area increases as ore is withdrawn from the column (Kvapil , 1980). This becomes important to block caving since eventually a vertical cylinder of draw will be approximated as this ratio increases without bounds. Figure 3 shows this result. The width of this draw cylinder is a critical dimension for the determination of draw point spacing in relationship to block caving mine design. McCormick (1968) for one, felt that within this cylinder of draw, mass flow would take place. This is the

Jan 1, 1981

By J. M. Schopt

COAL petrology is the study of the lithologic composition and texture of coal and includes megascopic as well as microscopic differentiation. Coal petrography is a quantitative study, principally (but not exclusively) microscopical in nature. The distinction between coal petrologic and coal petro-graphic studies usually is not important, but it is important to recognize that these studies differ materially from other types of petrology that deal primarily with minerals. The petrologic entities* of coal are less clearly distinguished than most minerals and the basis of distinction is not always clearly expressed. The relation of coal petrology to geologic, mining, and technologic problems is most evident when results of coal petrologic studies can be stated quantitatively. The chemical and physical composition of coal and the determination of its quality and properties are continuing problems. The source of these problems lies in the heterogeneity of coal and in its almost complete insolubility in ordinary solvents at normal temperatures. The empirical and comparative character of standard chemical coal analytic values is one of the consequences resulting from heterogeneity and insolubility of coal. Nevertheless, these coal analytic methods are highly technical and diversified. Coal petrol.ogy employs a group of similar analytical methods which provide information about coal that the other methods cannot supply. The heterogeneity of coal is most clearly demonstrated by means of petrologic studies. The properties utilized in coal petrologic studies are related to texture (size, form, and association), hardness, light reflectance, and light absorption and transmission (color). Size relations are most evident but are commonly overlooked. Coal is classed chemically as a mixture, and chemical analyses thus show the composition of the sample as a whole. Geologically coal is an organic clastic deposit, derived from diverse plant fragments and particles having a size range comparable to that of a conglomerate or breccia. The mixture of different materials that compose coal, large and small, can be realized only by microscopic study. This is because the fundamental cellular units of plants, from which coal is formed, are microscopic in size. The kinds of altered plant particles and fragments in coal have specific differences in hardness, reflectance, and color that signify differences in composition. These differences must be taken into account in evaluating the aggregate properties of coal. Terminology and Texture Full discussion of terms applied by various petro-logists in analysis of coal is beyond the scope of this article. For convenience the simpler types of petrologic entities that are defined without reference to lithologic occurrence or texture will be called coal components. Fig. 1 lists reactive and relatively inert

Jan 1, 1957

By David Keys

THE actual procedure in estimating depth of overburden from mag-netic observations made on the surface will vary with the form of the deposit and any theoretical discussion will apply only so far as the form of the deposit conforms to the mathematical premises on which the theory is based. Since the shapes of natural deposits in the field cannot be expressed rigorously in mathematical form, the best that can be done is to assume some simple form and deduce results. Fortunately many small variations in form produce only slight changes in the estimated depth of overburden, therefore the methods have a definite practical value. For the theoretical treatment, magnetic ore deposits may be divided roughly into three classes, depending upon whether the magnetic anom-alies may be considered to arise from (1) a single magnetic pole, (2) a dike or (3) a magnetic doublet. Particular cases, falling under one or other of these classes, have been discussed by different authors.1-4 In general, it may be stated that when the magnetic effects as measured on the surface are due only to one pole of the body, the other pole being so remote that its effect may be neglected, the resultant anomaly F at any point will vary as the inverse square of the distance r of the point from the pole, which may be expressed mathematically by F = k/r2, where k is a constant. When the deposit occurs in the form of a long, thin dike, the resultant anomaly will be of the form F = k&apos;/r and when the deposit is in the shape of a lens, so that both poles have an appreciable effect on the surface, the result will be similar to that caused by a magnetic doublet, and the form will be F = k&apos;/r3. The particular class under which a deposit falls may be deduced from the results of the magnetic survey. The second class is readily found, but there may be difficulty in deciding between the first and third. Isody-namic contours of both the vertical and horizontal anomalies will often be a good guide in making a correct decision.

Jan 1, 1937

An abstract of a paper from the Canadian Mining and Metallurgical Bulletin of August 1978 by E. Stamboliadis, J. McHardy, T. M. Salman, Department of Mining and Metallurgical Engineering, McGill University, Montreal, Quebec, states that: “The recovery of gold, silver and other heavy metal cyanides from mill solutions is technically possible using the ion exchange technique. However, the costs involved are greater than the costs of the zinc precipitation technique used for gold recovery. There are two main reasons for this: one, the fact that in gold ore cyanidation metal cyanides other than gold and silver occupy most of the resin capacity and hence reduce the adsorption efficiency of the resin for the Au and Ag cyanides; secondly, the high cost of the eluting agents.” Resin, therefore, cannot in most cases be efficiently used for recovery of precious metals. With copper in solution, only 1.47% of the resin capacity is used for gold and 0. 8970 for silver; the rest is occupied by unwanted metal cyanides, such as copper occupying 73.7%. On the other hand, although activated carbon will adsorb copper cyanides, they will be preferentially displaced by gold and silver cyanides. Ion exchange is by one or two orders of magnitude more expensive than the conventional method of zinc precipitation. The cost of removing impurities, such as copper from the resin, is greater than the cost of recovering gold. With an oxide ore amenable to cyanidation and with a low content of other metals, such as may occur with some of the Soviet gold deposits, ion exchange would be an efficient as Carbon-In-Pulp.

Jan 1, 1981

TO WE BOARD OF DIRECTORS OF THE AMERICAN INSTITUTE OF MINING AND METALLURGICAL ENGINEERS Gentlemen:-The following report covers briefly some of the more important activities of the Institute during the year 1923. In my report for the year 1922, I drew attention to the falling off in membership of the Institute due to the depressed condition of the mining industry in several lines and the inability of many of our members to find profitable employment in mining or its associated branches. A number who were unemployed during 1922 established connections during 1923, but a still greater number have been forced to resign or drop their membership during 1923. Fortunately, the number dropped is not so great as in the previous year. The Employment Service conducted by the four Founder Societies bears witness to the trend in business. For the young men just out of college, there are plenty of opportunities at small salaries, there are plenty of opportunities for them as laborers; but for the mature members, those of experience, there are few calls. During the last eighteen months, our Employment Service has been able to place only six of our members out of every hundred engineers for whom it has found work. Another loss which this Society has suffered, but which is not felt so keenly by our sister societies, is in its foreign members. The A. I. M. E. has always had a large foreign membership, but of recent years exchange has been so heavily against many European and South American countries that a large number of members residing abroad have been compelled to relinquish their membership. Almost invariably these members express keen regret because of the necessity that confronts them, and almost invariably the writers express hope that present conditions will not last long and that they will soon be able to ask for reinstatement. Having stated the darkest side of the picture first, it may now be drawn to your attention that in spite of these losses the number of persons applying for membership was decidedly encouraging. From the quality point of view, the membership has not gone backward. The Membership Committee has declined to recommend many

Jan 1, 1925

By Harry M. Conger

It is a pleasure for me to keynote this first Western Regional Minerals and Coal Conference here in the Black Hills of South Dakota. It is pleasing for two main reasons. First, Homestake Mining Company has been associated with the Black Hills since 1875 when gold was discovered following Custer&apos;s trek through the Hills during 1874. Second, the future mineral development of the Black Hills will depend, to a great extent, on minerals and metals covered in this conference. The metals and minerals that are featured in this conference have unique similarities--and important differences--and therefore, will be of great interest to all who are involved in our industry in this area of the country. Precious metals have always been, and likely will always be, subject to political influence; they are only partially affected by the demands of our industrial economy. Energy minerals, while more directly affected by industrial stimulus, are also politically sensitive. In this regard, the need for a minerals policy affecting the energy sphere has been made very clear to us in the last five years. More importantly, the lack of a national policy and purpose relating to our total future energy needs has severely affected the overall economy and security of this country. Very briefly today, I would like to outline for you my thoughts on the future of these most important minerals. I will start by a discussion of precious metals, primarily my favorite precious metal, gold. A brief history of gold will be helpful in setting a perspective for forecasting its future although it is difficult to give a brief description of a metal that has been prized by man for over 6,000 years. Until recently, as you know, gold was held by the Federal government as a metal to be owned by the government only and

Jan 1, 1983

By H. M. Howe

One of the little electric-resistance magnesia crucible-furnaces which I designed for the metallurgical laboratory of the School of Mines of Columbia University is shown, in vertical section, of full natural size, in Fig. 1. The furnace itself consists of two semi-cylinders of magnesia, A A, with a cover of magnesia, B B, and a stopper, C, also of magnesia, which is perforated to admit the leads x, y, of a thermo-electric couple. The furnace is heated by the spiral of platinum wire, D D (entering and departing by the openings I and K), through which a current of any desired strength is passed, bringing it to incandescence, and to ally temperature, not above the melting-point of platinum, which may be desired. The crucible E, actually used in this furnace, is also of magnesia. I have heard of some unsuccessful attempts with furuaces of this general class, and have attributed these failures to the use of siliceous materials for the furnace-walls. Of course such a result is what we should expect, since the silica mould readily be electrolysed by the current, and the resultant silicon would alloy with platinum ; but the little magnesia furnace here clescribed seems to be wholly free from this objection. It has been used in my laboratory for some months, and temperatures, up to 1100° C, hare been developed in it over considerable periods of time—indeed, it has been held near 1400" C. for about two hours—without indication, thus far, of any deterioration of the platinum. In the section shown, F F are a pair of steel disks, bound together, but separated by the inverted thermo-junction, N, of the thermo-electric pyrometer. This arrangement permits the observation and record of retardations in the heating and cooling of F F—in other words, the determinations of the cooling curves of steel—a purpose for which the furnace has been used, thus far, more frequently than in the determination of meltingpoints. For the latter operation, however, it is also suitable.

Jan 1, 1902

By W. B. Lilienthal

A considerable saving in time and money has been effected by use of a specially designed stainless steel container for laboratory drilling mud test work. This container involves use of a standard tall-form stainless steel beaker for service in which the mud sample is heated to an elevated temperature and maintained there for protracted periods of time, while undergoing agitation to facilitate mixing of mud components. Agitation is accomplished by rotating the filled containers on motor-driven rollers within an oven. Several porcelain balls are generally placed in the containers to further improve agitation. Soft glass containers (.Mason jars) were used in this service in early work, and were found to be unsuitable for the following reasons: 1. Poor resistance to thermal shock. 2. Containers could withstand only relatively low pressures. 3. Accidental breakage in handling. 4. Chemical deterioration and subsequent mud contamination from reaction of high pH muds with the glass at elevated temperatures. Pyrex containers were also considered, but, inasmuch as they provided improvement only in items 1 and 4 listed above the additional cost was not believed to be justified. A scale drawing of the container is shown in the figure illustrating details in cross-section. A pressed stainless steel lid was fabricated to match the rolled edge of the beaker

Jan 1, 1950

By C. M. St. John

INTRODUCTION The stress redistribution accompanying the excavation of a deep tunnel may induce failure of the rock. The role of the support system is to control the extent of the failed region and hence to limit closure of the tunnel within an allowable amount. In such circumstances, the design of the support system is generally based on the Ground Reaction Curve (GRC). The GRC is the relationship between the support pressure and the induced displacement at the tunnel wall for a circular tunnel under hydrostatic loading. In the calculation of the GRC (see Brown et al. (1983) for an exhaustive list of reference), the rock is generally treated as an elastoplastic material characterized by cohesive-frictional yield strength and by dilatancy during plastic deformation. A recent analytical development (Detournay, 1983) has allowed the generalization of the GRC concept for some cases of non-hydrostatic in-situ stress fields (Detournay and Fairhurst, 1982). As an application of that development, this paper describes design charts that provide powerful means of performing parametric analysis for tunnels subject to non-hydrostatic loading. BACKGROUND The in-situ stress in a plane perpendicular to the tunnel axis can be decomposed into mean and deviatoric components, Po and So (see Fig. 1). Since it is assumed that the rock is characterized by a Mohr-Coulomb yield strength, the deviatoric invariant So must be less than the limiting value Sl0 given by

Jan 1, 1984

By S. Fukushima, E. Kimura

In the Mitsubishi beneficiation process of ilmenite, chlorine is regenerated in the dechlorination furnace where the gases produced from a selective chlorination of ilmenite are directly introduced. The present paper describes a reaction mechanism and mixing characteristics of the reactant gases for dechlorination of ferric chloride with oxygen. A furnace of a small diameter where the reactant gases passed through in the state of nearly plug flow was used for determination of the effects of temperature and of partial pressures of ferric chloride and oxygen on the rate of the reaction. The experimental data of the reaction rate were applied to various models for calculations of the rate equations and the most suitable reaction model was determined. The results of the experiments also showed that effects of gas mixing onto the reaction rate could not be ignored, so that experiments of gas mixing was carried out. Gas flow patterns and scale effects were observed with use of transparent model furnaces of different sizes.

Jan 1, 1976