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By Howard E. Kremers

Since the discovery of the first-known rare earth elements more than a century ago, these metals have always been of academic interest. It is not so well known, however, that a rather stable, respectably large industry based on rare earths and their related materials has been in operation for more than 60 years. Rare earths, of course, are the elements having atomic numbers 57 through 71--lanthanum through lutetium in the periodic table. The most important commercial members of this group are mixtures of the lower atomic-numbered rare earths, and cerium. Although yttrium is not a rare earth, it occurs with rare earths and its properties are so similar to them that. it must be included in a discussion of these elements. In addition, thorium is important to most producers of rare earths because their ores generally contain this element. Thorium extractive metallurgy and technology is closely related to rare earth chemistry due to the frequent similarity of properties.

Jan 4, 1962

By Paul A. Beck

It is well known that the hardness of metallic single crystals, like that of polycrystalline metals, increases during deformation (hardening by cold-work). It is also known that, as a consequence of deformation. the metallic material acquires an evident thermodynamic instability, revealed, for example, by the fact that the increased hardness gradually decreases with time, especially at elevated temperatures (softening by annealing). The temperature at which the stabilizing process begins is different for various metals, and for any metal it depends on the amount of deformation. Such stabilization of deformed metals may proceed in two different ways: through recovery, and through recrystallization. The former process allows the unstable deformed metal body to approach stability gradually and without visible change in the grain structure; the latter process, like an allotropic transformation, yields directly the undeformed stable "phase" in the form of new undeformed crystals, which, starting out of a certain number of nuclei, grow into and " consume " the deformed hard material. The extent of stability attainable through recovery is limited, especially if the deformation of the metal crystal or crystals involves not only the gliding along slip planes, but also the bending of the slip lamellae, or at any rate the bending of comparatively large parts of the crystal lattice. In such cases, for instance in bent single crystals or polycrystalline metals subjected to any deformation, recovery will not as a rule be able to restore the "istraight" undeformed lattice, and stability can be attained only by recrystallization; that is, by the consumption of the bent crystal lattice parts by new, undeformed crystals—a much more drastic process. It is evident that the part of the surplus free energy stored in deformed crystals, which is present in the form of the elastic energy of the bent lamellae, is in these instances not considerably involved

Jan 1, 1937

By R. P. Ehrlich, D. A. Dahlstrom

In the hydrometallurgical circuit, many phase separation steps are usually necessary. Typical steps are pregnant liquor - leach residue separation by counter- current decantation or continuous vacuum filtration, clarification of liquids prior to precipitation, ion exchange or solvent extraction, dewatering of final product, etc. The paper discusses the more recent advances in these areas and considers general operating parameters and cost factors. In addition, emphasis is placed on future needs because of the growing importance and necessity of hydrometallurgical processing of minerals.

Jan 1, 1973

By Harvey P. Knudsen, Young C. Kim, Edward Mueller

Abstract-This paper describes the results of a comparative study of the geostatistical ore reserve estimation method over three conventional methods; the polygon method, the inverse of the distance squared (IDS) method, and ELIP which is similar to IDS. Each method was evaluated on its ability to accurately predict individual block grades for one bench of the Pima mine, located near Tucson, Ariz. Results at the Pima mine indicate that the geostatistical method is no better or worse in predicting block grades and total tonnage than the ELIP or IDS methods. In contrast, the polygon method is clearly inferior. All of the methods would have given better results if geology had been included in the block model. At already producing mines ELIP or IDS may be good choices since they involve substantially less cost in computer time. For prospective or new properties the geostatistical model is more attractive due to its ability to construct confidence limits on the estimates.

Jan 1, 1978

By H. J. Freyn

The American iron and settl manufacturer finds himself to-day barely at the threshold of enormous possibilities for practicing rational economy in the use of fuels.

Jan 1, 1915

By Thomas R. Couzens

This chapter covers certain aspects of open pit production planning based on experience, pointing out approaches to planning that may help produce a realistic picture for evaluation and operation The subjects discussed are roads, preproduction stripping, dump planning, dewatering, the relationship of production planning to equipment selection, and computer methods for the short-range or operational pit planning process Actual determination of ore limits, pit design, and production schedules are covered in other chapters This discussion is somewhat general. Specific problems that occur in mine planning are extremely varied, and it is not possible to cover many of them in a chapter, therefore, only some of the principles that are important in the approach to open pit production planning problems will be discussed.

Jan 1, 1979

By McAuliffe, Eugene

THE TERM "engineer" has been defined in many ways by many men broadly speaking the statement that "an engineer is one versed in or practicing any brar1c.h of engineering" is sufficient. A rather close relation exists between the sciences of surgery and engineering. A successful surgeon must have the capacity to perform the most delicate work, under extremely circumscribed conditions. This portion of his education is purely mechanical and although marvellous in itself, it must remain secondary to that greater possession, a thorough knowledge of human anatomy coupled with a comprehensive understanding of human psychology. In sub- stance, the surgeon must not only know how to operate but what is more important, he must be able to decide when, if ever, the operation should be undertaken.

Jan 1, 1932

By Neil H. Cole

Cost and price inflation and financial gearing through loans are characteristic of modern resources projects. Conventional discounted cash flow and 1P.R analyses, in real terms, and without financing, have inadequacies which can yield misleading results. The degree of improvement in value for project equity owners is limited to the value of the additional tax benefit accorded through the financing instrument used. Debt financing may be low in price and value, but its priority means that the equity owners assume a higher risk, thereby increasing the cost, or price, of their capital. The cost of equity capital, or investment hurdle rate, is related to the Capital Asset Pricing Model. Distortions do occur, with inflation, due to depreciation effects, which can cause the adoption of misleading project rate of return or hurdle rate criteria. For investment decisions, the greatest accuracy possible in forecasting is essential, especially for inflation rates,

Jan 1, 1985

By AIME AIME

SIR HENRY CORT HAROLD CARPENTER, great-great-grandson of Henry Cort, famous as the initiator of iron puddling some 150 years ago, carries on the tradition of an illustrious name. Newest of those elected to the Institute's roster of Honorary Members, Sir Harold is distinguished for his achievements in the field of metallurgy as an investigator, teacher, administrator, organizer, and director of research. His interests in research have been in both the ferrous and non-ferrous fields. His name is particularly honored in its association with the establishment of fundamental con¬stants and of critical ranges of iron and iron alloys, and with original and fundamental studies of the preparation and properties of metal single crystals.

Jan 1, 1938

Jan 1, 1970

By E. R. Funk, H. Udin, J. Wulff

The surface tension of solid silver is measured by a refinement of the Udin, Shaler, and Wulff technique. The tests were made in a purified helium atmosphere at four different temperatures and various times. The average of the results is y = 1140 + 90 dynes per cm for the range 875° to 932°C. A SUCCESSFUL measurement of the surface tension of solid copper was reported by Udin, Shaler, and Wulff.' They performed experiments on copper held in vacuum within 100°C of the melting point. At these temperatures, the creep rate in 5 and 3 mil copper wires was sufficient to permit determination of a balance between the contractile force of surface tension and the extending force of small copper weights joined to the end of the wire specimens. By suspending a series of variously weighted specimens and measuring the change in a gage length during the test, the balancing applied load could be found. This point of zero strain is a measure of the surface tension. The mathematical formulation of this gives: w = r y [1] where w is the weight for zero strain; r, the radius of the wire; and y, the surface tension. A subsequent note by Udin pointed out that eq 1 applies only to single-crystal specimens. Since the specimens used revealed a "bamboo" structure upon

Jan 1, 1952

R. L. Fleischer (Department of Metallurgy, Massachusetts Institute of Technology)— The authors have presented valuable observations of oehavior of aluminum at intermediate and high temperatures. I should like to consider their interpretation of the appearance of cross slip plane traces in sample B-3 as partly due to "bending of the crystal due to grip constraint." Because bending moments might be set

Jan 1, 1960

By K. L. Meissner

IT is well known that the so-called pure aluminum contains noticeable amounts of impurities, chiefly iron and silicon, and many investigators have studied the forms in which these impurities exist. Hanson and Archbutt1 state that iron exists in aluminum as FeAl3 and silicon as elementary Si. The solubility of FeAl3 in solid aluminum is practically zero, or at, least so small that the smallest trace of this compound is always visible as a separate constituent. Under the microscope an untrained eye can hardly distinguish, without etching, the two constituents FeAl3 and Si, but they can be differentiated by suitable etching reagents. Anderson2 also found the same results. At the same time, Merica, Waltenberg, and Freeman3 found a constituent of unknown composition. They found a small thermal effect, at 610° C., on the cooling curves of aluminum with small amounts of iron and silicon. The intensity of this effect increased with increasing silicon content, until an effect occured at 576° C. due to the eutectic between aluminum and silicon. The authors ascribed the effect at 610° C. to a compound, which they call "X constituent." It was thought to be a ternary compound containing iron and silicon and could be observed under the microscope as dark particles. Dix4 has published unetched photomicrographs of an aluminum with 0.51 per cent. iron, 0.99 per cent. silicon, and 0.32 per cent. copper that shows three constituents: the dark Si (black in the figure), the lighter FeAl3, which appears in half tone and crystallizes in needles, and a constituent of the same color as FeAl3 but of different crystal form, often resembling Chinese script. This last constituent, Dix thought, is a compound of Fe and Si; not the compound FeSi but a compound containing a relatively small amount of silicon. Therefore an alloy of aluminum, iron, and silicon (the copper should not be regarded in the following considerations) must contain the following four constituents: Al, FeAl3,

Jan 1, 1926

By James D. Reilly

13.1-1. Introduction. COAL RESERVES OF THE UNITED STATES. Bituminous coal is the most abundant fossil fuel in America. With reserves of 1,660 billion tons and assumed recovery of 5070, there is more than 830 billion tons of recoverable coal--enough to assure ample supplies of energy for centuries. Looking at Fig. 13.1-1, coal is found in a majority of the states, including [ ]

Jan 1, 1968

By Robert L. Bates

An industrial mineral, says the Glossary of Geologic Terms, is "any rock, mineral, or other naturally occurring substance of economic value, exclusive of metallic ores, mineral fuels, and gemstones; one of the nonmetallics." Probably most geologists and engineers would accept this simple and straightforward definition, at least as a general statement. On analysis, however, certain anomalies crop up. For example, it may be considered arbitrary to include industrial diamond and corundum, but to exclude their precious varieties, gem diamond and sapphire. So the present volume has a section on gems and gem materials, in spite of the definition. Another problem arises when we try to define precisely what is metallic and what is nonmetallic. Bauxite and ilmenite certainly qualify as metallic ores, but both are also raw materials of important nonmetallic substances; hence they are included in the book. A third anomaly is that, by common consent of geologists, engineers, mineral economists, and others concerned, the term industrial minerals may include not only rocks and minerals but also certain manufactured products like cement and lime, and even mixed groups of natural and artificial products, such as abrasives and refractories. Thus the central realm of the industrial minerals is clear enough, but its boundaries tend to be indefinable. Since a definition that allowed for every irregularity in the outer fringes would be excessively un- wieldy, the one quoted above may be considered satisfactory. The expression industrial minerals is commonly equated with nonmetallics, and with the somewhat more precise phrase industrial minerals and rocks as in the title of this book.

Jan 1, 1975

By W. G. Whildin

This paper will be confined to a discussion of the methods in use in the property of the Lehigh Coal and Navigation Co. in the Panther Creek valley.

Jan 1, 1915

By H. A. J. Wilkens, H. B. C. Nitze

At the Atlanta meeting of the Institute in October,' 1895, some brief remarks were made by Mr. Wilkens on the above subject. It is the object of this paper to set forth the substance of these previous statements, embodying therewith additional information gained since that time, and a brief illustrated description of the method and means of the separation.* Lack of time will unfortunately not allow as complete a resume of the subject in all its phases, especially those relating to the scientific side of the question, as its novelty and importance would warrant, so that even this paper must be considered a preliminary one. It is hoped that at some future meeting of the Institute we may find an opportunity of presenting supplementary data of interest. The paradoxical title above used requires some explanation. The term " non-magnetic material " is applied to such substances as have heretofore been considered non-magnetic in the arts, more especially in the practice of ore-concentration. Scientifically, it has been shown by Faraday, Plucker, Wiedemann and other physicists that magnetism is an inherent property common to all substances, solid, liquid and gaseous, i.e., all suhstances are either attracted or repelled by the poles of a magnet, although ill the great majority of cases the manifestation of this

Jan 1, 1897

By Stuart M. Buck

The term "splint" seems to have been adopted to describe the fracture of the hard bituminous coals of West Virginia. It is not a scientific name, but rather a trade term, and does not indicate a correspondence with English splint. At present it is a popular word, and is very loosely applied to coals of various qualities, in the desire & improve their sale. The Kanawha splint is distinguished by its hardness, dull lustre, coarse fibrous structure, its purity, and especially its resistance to atmospheric influence. It kindles very readily, burns with a bright flame, but does not cake, so that a lump when half consumed, may be broken by a slight blow in its plane of cleavage, though it will resist a strong blow in any other direction. I have seen pieces that have been exposed to frost and sun

Jan 1, 1882

[Aamot, Olav Crone, (M'29) Chem. Engr., Elektrokemisk, Raadhusgt. 23, Oslo, Norway. Abadilla, Quirico A., (M'38) Min. Engr., Dir. Bureau of Mines, Manila, P. 1. Abbott, Agatin, (J'40) Asst. Geol., Trench Mine, Patagonia, Ariz. Abbott, Clarence E., (M'04) Civil Engr., V.P., Tennessee Coal Iron & R.R. Co., 1642 Brown Marx Bldg., Birmingham, Ala. Abel, Raymond L., (M'28) Prof., Chem. Engrg., Univ. of Pittsburgh, Pittsburgh, Pa. Abel. Walter D., (M'32) Min. Engr., Div. of Corporations, State of Calif., 403 California State Bldg., Los Angeles, Calif. Abele, Louis T., (M'31) 4800 Patterson Ave.. Richmond, Va. Abell, Leo M., (M'31) Research Met., Mount Morgan Ltd., Mount Morgan, Queens., Australia. Abenius, Hakan V., (M'37) c/o Falu Gruva, Falun, Sweden.]

Jan 1, 1940

By J. G. Koenigsberger

THE electrical specific resistance of rocks in the field is measured by sending a current through a medium of great volume, compared to the electrodes, whose resistivity should be measured. The whole resistance can be determined by the Wheatstone bridge and the specific resistance calculated by a well-known formula. The resistivity of some rocks in place in Germany and in Switzerland is given; first, of a rock near the surface, and especially near electrodes. Practical applications are made in the determination: (1) of the continuity of a conducting orebody; (2) of the surface area of an orebody; (3) in the detection of a water-bearing fault in a salt mine. Preliminary observations are described: (1) on the influence of the depth of ground-water table; (2) on the detection of gas under high pressure in coal seams. The observations in this paper of the electrical resistivity of rocks and soil in place are along the lines of the very interesting method and results of the Messrs. Gish, Rooney, Hotchkiss and Fisher.1,2 All the work described has been done since 1920.

Jan 1, 1928