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By Leo J. Miller

It is both an honor and a pleasure for me to be the keynote speaker for the Paul F. Kerr's Symposium on Applied Mineralogy. Professor Kerr was a man for all seasons to his students, and he treated all students as distinct individuals. Philip Bethke in his memorial to Dr. Kerr summed up our remembrance best by stating that "We have lost our most successful educator-administrator-scholar, who was our steadfast teacher-counselor-mentor-friend." His unique trait was the ability to bring out the best in a variety of individuals In order that their performance was at the peak of quality.

Jan 1, 1985

By J. W. Freeman, J. P. Rowe, R. F. Decker

HEAT-to-heat variations in properties of an alloy of constant nominal chemical composition have been a perplexing problem to the metallurgist. These heat-to-heat differences have been especially baffling in high-temperature metallurgy. In order to establish fundamental reasons for these heat-to-heat variations, the National Advisory Committee for Aeronautics has sponsored and financially assisted an extended research program on heat-resistant alloys at the University of Michigan. As part of the program to find the contribution of processing variables, Frey, Freeman, and white' studied effects of heat treating on nickel-base alloys and Ewing and reeman' investigated effects of hot-working practice on N155 alloy. To extend the program to the study of effects of melting practice on high-temperature properties, a 55 Ni-20 Cr-15 Co-4 Mo-3 Ti-3 pct A1 composition was selected for experimentation. The objective of this program was to establish the melting-practice variables which influenced the hot-working characteristics and creep-rupture properties and, at the same time, establish the metallurgical mechanisms for the effects. During the course of the investigation of practices using vacuum melting, it became increasingly evident through chemical analyses supplied by industrial concerns that a major variable was melt reaction with the crucible. This paper is devoted to the results of this phase of the melting-practice study. EXPERIMENTAL PROCEDURES Experimental 10-lb heats were induction melted in the University of Michigan vacuum-melting unit with the melting practices outlined in Table I. Aim analysis for the basic alloy, in wt pct, for all heats was as follows: Cr Co Mo Ti Al 20.0 15.0 4.0 3.1 3.1 Mn Si C Ni 0.12 0.12 0.08-0.15 Bal. Small amounts of boron and zirconium were added to certain heats as listed in Table I. These additions

Jan 1, 1959

By O. A. Cheadle, F. E. Lane

ThE computer program for arbitrary crystal systems reported by Camp and Clum' has been modified to make it more convenient for hexagonal crystals. The program' uses the Miller indexes (hkl) which can be confusing for hexagonal crystals while the modified program uses the Miller-Bravais indexes with four axes; e.g., the angles between the (110) planes, Fig. 1, are 0 and 90 deg but in the (hkil) system the angles between the (1150) planes are 0 and 60 deg. If a Laue photograph is taken of a crystal oriented with the prismatic planes nearly parallel to the film then the spots on the stereo graphic projection will be from high-index planes. The probable positions of the low-index planes, e.g., (0001) plane, can only be obtained from the intersection of zones and this is not accurate to 1 or 2 deg. The number of planes considered by the program (card 1)' has to be limited to the ones of low index or the program time is excessive but a solution will not be obtained if one of the spots has an index that is not being considered. To overcome this problem the program1 was modified so that if no fit was obtained at *1 deg (card 3) of the tabulated angles then ±2 or ±3 deg was tried. If still no solution was obtained either due to one of the angles not being measured correctly to ±3 deg or because one of the spots was from a high-index plane, then the last spot was discounted and a fit tried for the remaining spots at i1 deg, and so forth. The minimum number of spots that the program will try to fit is five. If the limit on any individual index is 4 (card 1) and (h + k + l + 1) is six then twenty-three planes are considered and there are over 1000 interplanar angles. Many pairs of planes have very similar interplanar angles and with the errors previously mentioned the program will often produce several alternative solutions to a group of spots particularly at ±2 or ±3 deg. However without the program the alternative solutions would probably not have been found. If a large number of spots are used the number of possible fits is reduced. In the example shown in Fig. 2, if only spots which are on the film are used (case 1) the program gives six possible solutions, Table I. However if points 7 and 8 are also used (case 2) the program gives only one fit which also agrees with a standard projection of the crystal. In addition to time-saving the program ensures that a correct solution is obtained since it is unlikely that all the alternatives would have been gound manually; the first would probably be assumed to be the correct solution. The program has been used for zirconium crystals but is equally suitable for other hexagonal materials.

Jan 1, 1969

G. McMEANS*—This paper is a very good demonstration of the use of a new tool for the solution of industrial problems of a physical nature. To have solved this problem without the use of radioactive tracers would have required a far greater amount of investigation and work. The authors have described their work in such detail and in such a manner as to suggest the possibilities of the use of such tracer studies in the solution of many perplexing problems of industry. R. E. BREWER †—The authors are to be congratulated on this very excellent paper, which describes the results obtained by utilizing radioactive tracers in investigating the complicated reactions in the coking process. The paper has especial merit because the study was made under typical operating conditions in a commercial coke oven. Considering all the difficulties involved, the results obtained are excellent. My brief comments will relate primarily to the method used for determining the sulphur in the gas and to the value of the data obtained in stimulating further research. In discussing their results, the authors state (p. 17) that "Of the total sulphur charged to the oven in the coal 95 pct was accounted for in the coke and gas. Most of the sulphur unaccounted for is believed to have been lost in the gas, since the gas sampling system removed all the H2S but probably only part of the organic sulphur compounds present in the gas. Although sulphur in the acid-insoluble tar residue in the gas scrubbing bottles was determined and added to the total sulphur determination of each sample, it is doubtful whether an aliquot portion of tar for each sample was obtained." The reviewer believes that the authors might have obtained a better sulphur balance had they used an improved procedure for determining sulphur in the gas. The absorption train should have included a trap to remove the tar and am-moniacal liquor and a wash bottle containing 5 pct sulphuric acid to remove ammonia in the coke-oven gas before it entered the gas scrubbing bottles containing the ammoniacal cadmium chloride solution. Sulphur in the tar and

Jan 1, 1950

By W. T. Isbell, Carleton C. Long

Zinc recovery from lead blast-furnace slags has heretofore been an indirect process, involving, first, the fuming off and collecting of an impure zinc oxide, and second, the reduction of the zinc portion of this oxide to metal either by electrolytic or pyrolytic means. (In a variation of this process, blue powder is the intermediate product rather than zinc oxide fume.) In 1940, W. T. Isbell proposed that molten slag from the lead blast furnace or stock-pile slag melted down in a blast or cupola-type furnace be charged directly into an airtight container (i.e., furnace) provided with means to heat further the slag by passage of electric current and means to introduce the carbon (coke) necessary to reduce the ZnO constituent of the slag to zinc as a zinc vapor and CO. He also proposed that the zinc vapors so obtained be condensed in a Weaton-Najariant internal condenser directly connected to the proposed furnace. It was thought that the Weaton-Najarian condenser could liquefy zinc vapor from lean mixtures of vapor and noncondensable gases. Such condensers have been in commercial use! since 1936 at Josephtown smelter, where the source of zinc vapor is a column of coke and zinc-bearing sinter electrically heated (charge resistor). Condenser output when supplied with vapor-gas mixtures containing approximately 45 per cent zinc and 55 per cent noncondensable gases, varies from 18 to 30 tons of slab zinc per day per condenser, depending upon the heat-transfer area (length) of the condenser and the volume of vapor (furnace size) fed to it. Lead-smelting operations at the St. Joseph Lead Company's plant at Hercu-laneum, Mo., produce a slag containing 12 to 16 per cent zinc. For several years this slag has been stock-piled with the object of recovering the zinc values if and when a commercial method was invented. Evaluation of the possibilities of the proposed method was made by pilot-plant operation at Josephtown. The first plant, designed in 1940 and operated in early 1941, consisted of a single-phase, two-electrode furnace. The evolved vapors were burned. Electrical characteiistics of the molten slag, power requirements, coke requirements, and extent of zinc elimination indicated the feasibility of the proposed method. In the latter part of 1941 a second pilot furnace was constructed, to which "was attached a small (6 ft. long) Weaton-Najarian condenser in order to develop an over-all picture of zinc-in-slag to zinc-in-slabs. This furnace was operated in the early part of 1942 and yielded such promising results that a decision was made to design- and construct a commercial furnace. Feed for the pilot-plant furnaces was granulated slag. A suitable deduction (300 to 350 kw-hr. per ton slag) was calculated in estimating power require-

Jan 1, 1944

By William I. Watson

Problems encountered in beneficiating mineral raw materials become increasingly difficult as there is a shift to lower grade and more complex raw materials, and because of the economic need to strive for ever higher recoveries, higher grade products, and lower processing costs. Methods of attacking the many problems should include not only the familiar chemical and physical tests and equipment, but such techniques as X-ray analysis, infra-red analysis, differential thermal analysis, and the use of electron and X-ray microscopes. Many people in the mineral-treating field are unfamiliar with these newer methods and techniques. The differential thermal analysis method, in particular, does not seem to be very well known, even though it offers interesting possibilities in the study of many ore treatment problems.

Jan 7, 1959

By A. L. Holley

The members of the society are doubtless aware that the production of American Bessemer steel works is constantly increasing; that the same converters and machinery are doing more work every year. This enlarged output is due to various causes, chiefly the following: 1st. Better organization—better knowledge on the part of both managers and men, of the plant and the process; of the way to economize the more exhausting labor, and of the arrangement of the details of labor and operations so that they shall not conflict; also, more pluck—a greater willingness to take risks, or, more properly, such an intimate knowledge of the nature and capacities of the refractory linings in various stages of disrepair, and the probable be- . havior of the fluid metal at various stages of its treatment, that the precise nature of the risk may be better known, so that the works may be crowded to their full capacity. In the early practice, after getting four or five consecutive heats in a day, the men preferred to " let well enough alone," and to devote the remaining time to preparation for another turn. Now, thirty, and sometimes forty heats are regularly made during the twenty-four hours, day after day, without the frequent occurrence and without the fear of breakdowns or " messes," as the spilling of steel charges was graphically named in Sheffield. 2d. Although no new refractory materials have been developed, improved means of preparing such as we have, and of imbedding

By C. S. Herzig

Some time ago, in Mexico, our signal-bells in a 700-foot shaft caused us considerable annoyance by continually getting out of order, each time so delaying our hoisting operations that we naturally desired to remedy this evil. There were two mays open: either to patch up the old bell, which was of the ordinary pattern, every time it failed to work, or else to devise some new arrangement.. On consultation with our foreman we designed a signal-device which, during the number of months I watched its operation, worked satisfactorily, without once getting out of order. We sought to produce a simple device, in which no greater pull on the lever would be necessary from one level than from another; to counterbalance independently the weight of the pendant bell-rope, so that there would be no direct weight on the working-parts of the bell itself, and likewise to arrange it so as to necessitate only a light pull on the lever in signaling; and, finally, to make some sort of trip-arrangement, so that whenever the signaling-lever underground passed through a certain arc the signal would be given in the engine-room. By this means we wished to obviate the ill effects of sudden heavy pulls and rough usage in general, such as all signaling

Jan 1, 1901

By E. C. Harder

AT a Meeting of the New York Section, on May 23, 1918, the sole subject of discussion was the nature and occurrence of iron ores in certain parts of the world.? Owing to the importance of this subject, it has been deemed' advisable to publish the remarks made at that meeting in the form of a paper, for presentation at the Milwaukee Meeting, instead of in the usual place, under News of Local Sections. The remarks related to the following districts: Brazil, by E. C. Harder, of the U. S. Geological Survey; Scandinavia, by Waldemar Lindgren, of the U. S. Geological Survey; Cuba, by C. M. Weld, of the U. S. Bureau 'of Mines; Southern Europe, by A. C. Spencer, of the U. S. Geological Survey; China, by H. Foster Bain, of the U. S. Bureau of Mines; Alsace-Lorraine, by Sidney Paige, of the U. S. Geological Survey. BRAZIL By E. C. Harder During the years immediately preceding the war, the iron ores of Brazil were attracting the attention of iron operators both in Europe and in the United States. This was clue to the large quantities of practically undeveloped ore available, and to its great purity. It is reasonably safe to state that had capital not been diverted from the exploitation of these deposits to war purposes, Brazilian iron ores would probably now be offered in European and American markets. It is certain that after the war these ores will play a prominent part in the economic reconstruction of Europe and perhaps in the development of America.

Jan 9, 1918

By James H. Boettcher, W. Durand Eppler

INTRODUCTION In the second quarter of 1979, Rapid Mining Co., Inc. ("Rapid") inquired whether Crocker National Bank ("CNB") would provide $4 million in term loan financing to help ("Dry Creek") acquire the outstanding shares of the Dry Creek Coal Company ("Dry Creek") in West Virginia. Prior to approaching CNB, Rapid had sought financing with the assistance of a financial advisor from a number of commercial banks without success. A summary of the initial terms requested by Rapid is shown in Table 1 compared with the actual terms on which the transaction closed. It is not difficult to note that the two sets of terms differ significantly. This is often the case when financing requests based on the expectations and vision of a mine developer are juxtaposed with more pragmatic requirements of a commercial bank. The "art" and fund of structuring financing plans for mining ventures (highly leveraged acquisitions or grass roots) comes in working with mine developers to arrive at a final financial structure that meets their objectives and constraints as well as those of the bank or other financial institutions providing much of the financing. Beginning with the terms requested by Rapid and ending with the terms that closed the transaction, this article briefly describes the process we went through with Rapid Mining. The Seller and Buyer The Dry Creek Coal Company was established in 1961, after its owner acquired the coal leases from Republic Steel. Republic has mined the primary coal seam from 1948-1961. Dry Creek was owned as a subchapter S corporation (i.e., for federal income tax purposes, income is taxed at the shareholder level) and had been run on a low key basis. Since the company had virtually no debt and limited cash needs, the owner produced primarily when rail cars were available and income was required. Output was therefore erratic as is shown in the top of Table II, but the result was a profitable little company with an attractive free cash position. Because the owner wished to retire and enjoy his wealth in a more readily spendable form, he had put the mine, with stated recoverable reserves of approximately 13 million tons, up for sale. In contrast, Rapid Coal's investors consisted of a number of investors of disparate financial situations. They had agreed upon a primary objective of income maximization and planned an annual production rate of 120,000 TPA which they and the current owner believed realizable. The Formulation of a Financing Structure Figure 1 presents a simplified overview of the sequence of steps taken in the financing process which lasted approximately three months from start to finish. Since banks see many requests for funding and considerble time is required to follow up on each, an important step was determining, after a brief review of the materials provided to us, whether the basic "eonomic entity" was viable. In this case, the size and quality of the reserves, the inherent operating cost characteristics, the sales arrangements, the management/labor situation and Rapid's principles all appeared to be sound enough to warrant investing the time necessary to do a thorough analysis of the project. Once this decision was made, the evaluation and analytic process shown in Figure 2 was initiated. The first and most fundamental concern of any banker is whether the loan will be paid back as scheduled from the cash flow generated by the project. The amount of debt relative to the owner's equity is of course crucial in such a determination. Before the debt/equity issue was addressed, however, a number of more qualitative factors had to be studied and if

Jan 1, 1985

By H. Becke, D. Stolnitz, D. Flatley, W. Kern

Extensive solid solubilities of CdTe (zincblende-type struckre) and InTe (B37 type) in each of the rock salt-type compounds, PbTe and SnTe, have been observed. Partial phase diagrams have been determined by thermal analysis and X-ray metallography. The limiting mol fraction. X,, of the solute in the rock salt-type a phase and the corresponding eutectic temperatures, T,, are: (PbTe)l-x(CdTe)x: X,- 0.2, T, =866°C; (PbTe),-,(lnTe),: X, - 0.35, T, = 646"C; (SnTe),-,(CdTe),:X,- 0.11, T, = 784 "C; (SnTe),-,(lnTe),: X,-0.53, T, = 630°C. The lattice parameters of the a phase decrease linearly with X, even in (PbTe),-,(CdTe),, where a, (CdTe) = 6.481A > %(PbTe) = 6.459A. This is taken as proof that the cadmium atom enters an octahedral interstice of the tellurium atom sublattice; i.e., the formation of the a phase entails the direct replacement of lead by cadmium. The a, us X curve extrapolates to 6.16A at X = 1, in agreement with the value predicted for an ionic crystal of CdTe; it is also consistent with the reported lattice parameter It is well-established that the compositions of intrinsic semiconducting and semimetallic compounds conform to normal valence rules.1"5 The apparent exceptions can be explained by taking account of anion-anion covalences, as in CdSb, or of multiple cation valences, as in In Te.'This empirical generalization is the basis of the chemical approach to semiconductors2 by which the properties of an intrinsic semiconductor are rationalized in terms of the ionic-covalent bonds necessary to saturate the valence-electron complement of the anion sublattice. A fundamental shortcoming of this approach is its disregard of long-range crystal interactions. It cannot, accordingly, deal with the phenomenon of charge conduction except through the use of ad hoc postulates. As an example, a crystal of CdTe would, in the valence-bond picture: be described in terms of electron pairs, each with the same discrete energy, localized between every cadmium and tellurium atom. This is, of course, contrary to the Pauli of the high-pressure rock-salt form of CdTe, corrected for decompression from 36 kbar. The free energy of formation of the a phase of pure CdTe at room temperature is calculated from the phase diagram to be +10 kcal per g-atom, in accmd with the value calculated from the transformation pressure. The standard enthalpy is +13 kcal per g-atom, and the standard entropy is +9 eu. The latter value implies the formation of extra classical particles, such as vacancies, interstitials, or nondegenerate charge carriers, but these alternatives are not consistent with the semiconducting properties and the densities of the a phase. The extrapolated values of the lattice parameters of (PbTe),-,(lnTe), and Spectively, for the rock salt-type modification of InTe. The corresponding interatomic separation is intermediate between monovalent and trivalent indium. The qualitative implications of the results are considered from the viewpoints of both valence-band theory and energy-band theory. principle, and is corrected by methods of molecular-orbital theory in which bonds are replaced by bands of molecular orbitals whose energies, E, depend upon a crystal-momentum vector, k.7 Each band is derived from a linear combination of atomic orbitals with two electrons required to saturate each molecular orbital in the band. In a crystal of N atoms containing z atoms in its primitive unit cell, there are 2 N/z states per band which lie in a region of k space bound by the Brillouin zone. In an intrinsic semiconductor, the bands can be grouped into valence bands which are normally filled and conduction bands which are normally empty. If the highest valence band and the lowest conduction band overlap anywhere within the Brillouin zone, the material is rendered semimetallic. The quantity defines the effective mass, m*, of an electron in a conduction band (or of a hole, i.e., an electron deficiency, in the valence band) and leads directly to the concept of charge mobility through the relation \x = et/m*, where e is the electron charge and t is the lattice relaxation time.

Jan 1, 1964

By Raymond E. Zimmerman

ROBERT E. HOCHSCHEID (Krebs Engineers, Cyclone Div.)--The subject article appears in the February, 1978, edition of Mining Engineering, and on page 190 carries the statement, "As most operators know, in a Water-Only cyclone, ability to adjust the vortex finder is quite important due to the sensitivity of this type of operations to variance in feed conditions and having to take them apart to make this adjustment is always a nuisance." Our experience as a manufacturer and supplier of Water Only cyclones does not agree with the above statement, and we offer the following brief discussion.

Jan 5, 1978

By Alfred Beasley

LEAD-REFINING practice at the. Bunker Hill differs to some extent from that of other United States refineries using the Parkes process, in that the Bunker Hill-has reverted to a custom used years ago of making two kinds of skims, or crusts, in the desilverizing kettles. Also, this was the first refinery to adopt the liquation process for silver skims as developed in Australia. Both of these ideas were brought to the attention of the operator by H. S. J. Sommerset, in the summer of 1924, while he was visiting metallurgical plants in the United States, when he was general superintendent of the Broken Hill Associated Smelters Pty., Ltd., of Port Pirie, South Australia. Since Mr. Sommerset's visit, United States patents on the liquation process have been issued to George Kenneth Williams, of Port Pirie, South Australia. At the Bunker Hill, the lead bullion is conveyed from the blast furnaces to the refinery in brick-lined cast-steel pots, each having a capacity of 5 tons, by a 20-ton electric crane, to which is suspended a Fairbanks-Morse suspension-type scale on which the gross, tare and net weights are obtained. The bullion is poured from the small bullion pots into either one of two kettles of 105 tons capacity, and when a kettle is entirely filled the heavy dross is removed by skimming it into a 5-ton pot suspended by the crane. The crane operator becomes proficient in the manipulation and a kettle is skimmed in a very short time. After the kettle is skimmed clean the bullion is pumped to a kettle of the same size alongside, where the bullion is cooled until it has almost frozen. By using two kettles for the drossing operation, one to accumulate the bullion where the heavy dross is removed, and then pumping to a clean kettle comparatively free of hangings, etc., it is possible to reduce the copper content much lower than if only one kettle is used in the operation. The average yearly analysis of bullion is given in Table 1.

Jan 1, 1930

(Members are urged to send in for this column any notes of interest concerning themselves or their fellow-members.) Members and guests who registered at Institute headquarters during the period Feb. 10 to Mar. 10, 1915: W. R. Van Liew, Batoum, Russia. Edward S. Jones, Scranton, Pa. Olof Wenstrom, Boston, Mass. Scott Turner, Tromso, Norway. D. G. Miller, Denver, Colo. A. H. Boyd, Denver, Colo. E. E. Olcott, New York, N. Y. M. M. Thompson, Morsemere, N. J. Francis R. Pyne, Elizabeth, N. J. F. C. Merry, Brooklyn, N. Y. Charles W. Goodale, Butte, Mont. Charles A. Filteau has been appointed General Manager for the Inca Mining & Development Co., Province of Carabaya, Department of Puno, Peru. Charles T. Kruse has been appointed Superintendent of the Jones & r, Loughlin mines in the Marquette and Menominee ranges.

Jan 4, 1915

The following list contains the names of members of whose deaths notices have been printed in MINING AND METALLURGY during the year ending April 1, 1937. Biographical sketches published in MINING AND METALLURGY are indicated in the last two columns. YEAR OF ELECTION - NAME - DATE OF DEATH - ISSUE CONTAINING BIOGRAPHY - PAGE I892 ALLDERDICE, TAYLOR May 20, I934 1919 ALTMEYER, MAURICE E June 9, I936 1917 ANDERSON, JAMES P Jan. I4, I937 I936 ANDERSON, O RAN M Jan. 12,1937 I908 AUSTIN, E. A I935 1914 BACON, MAURICE W Jan. 4, I936 Apr. I936 22I 1914 BARTHOLOMEW, WILLIAM F Oct. 7, I936 Dec. I936 602 I930 BERRY, HAROLD R July 1, I936 1915 Betts, Robert M Jan. 9, I937 HON

Jan 1, 1937

R. S. Shoemaker: Our first question is, is there a need for a grizzly before a primary crusher? What is its effect on crusher capacity and crusher maintenance? Is it worth the extra capital cost in a crusher installation? Vincent: ASARCO has a grizzly at Mission. Utah Copper uses grizzlies ahead of their gyratories. There is some quite abrasive ore at Mission, an argillite type of rock, which has a work index of 16.5 to 20, which is getting up toward the taconite classification. We get a life of 12- 16 million tons per set of concaves or per mantle with the grizzly ahead of the crusher. At Duval Corp., some 6 miles to the south of Mission, their crusher installation on a good, hard rock does not have a grizzly, and the last information I had is they get a life of about 2 ½ -3 million tons on their mantle and concave. At Silver Bell, our other copper unit in Arizona, they do not have a grizzly ahead of the gyratory and there they get a life of about 5-6 million tons. At Utah Copper, which we all know is a fairly soft ore, relatively speaking, they get a life of 24-27 million tons with grizzlies ahead of the crushers. I think a grizzly has a very definite effect on the life of the mantle and the concaves. As far as a jaw crusher is concerned, I think that usually it is desirable to have a grizzly if it is properly designed, which means it is self- cleaning. Otherwise I would not like to see one in the circuit.

Jan 9, 1967

By J. C. Rengel

Why and how the nuclear industry entered the electric power generation business is discussed in terms that nuclear energy was an undoubtedly additional energy resource and that it had promise of becoming a virtually inexhaustible generating power if breeder reactors could be devised. The growth of nuclear power, its total generation capacity, are related to the need of increasing energy requirements. The use of atomic energy for power generation will grow if it can compete economically with other fuels. The rate of growth, the time scale and direction of technical development is dependent on ore supplies. It is predicted that by 1980, 50% of all new power installations will be nuclear stations. INTRODUCTION Ten years ago, the nuclear industry was virtually unborn, the Atomic Energy Act of 1954 had just been signed, and peaceful applications of atomic power was little more than a phrase. Serious discussion of the practical application of nuclear energy to electric utility installations in the West was highly unlikely. The questions: Why and how did the nuclear industry enter the electric power generation business at all?; What is the predicted growth of nuclear power?; What technological changes do we predict?; How will the above changes affect the utilities? will in part be answered by this paper. WHY NUCLEAR POWER? The only justification for the West as for any other section of the country for atomic power is economics. Whatever energy source will provide the lowest generation cost will prevail; the only electric utilities which have shown an interest in nuclear power are those to whom it means lower generation costs. It is true that the Government sponsored the development of this technology long before there was any evidence of better economics; but a Government must take a very long-range view and it is the only type of organization that can afford to look more than twenty or thirty years into the future. The Government looked at projections such as shown in Fig. 1, which shows various rates of energy consumption, and matched these against estimates of fossil fuel resources. This showed that we will exhaust our low-cost fossil fuel supplies within 75 to 100 years and our total known fuel supplies within 150 to 200 years. The decision to invest in nuclear energy rested, therefore, on two arguments: a) It was undoubtedly an additional energy resource; and b) It has promise of becoming a virtually inex-haustable resource if breeder reactors could be devised if, while generating power, the reactors would produce more fissile materials than they consumed. This decision produced an unexpected bonus: nuclear power became competitive with fossil power much earlier than had been expected and, as shown in Fig. 2, forced the coal industry to take a hard look at its own position. I believe that the drop of coal prices shown here is the direct result of the entry of nuclear power into the energy supply business. At this point, it ought to be explained why and under what conditions nuclear power can be cheaper than fossil power. Fossil fuel cost to the utility is composed of two factors: a) Mining; and b) Transportation. As a result, the cost of fossil fuel to the utilities varies from 126, 106 Btu to 306, 106 Btu and higher. Nuclear energy is highly concentrated and the transportation factor becomes insignificant. Today the cost of nuclear fuel to the utility ranges between 156

Jan 1, 1967

By D. Geiselman, A. G. Guy

Single cvystals were grown from high-purity magnesium containing known amounts of nitvogen in the range 0.0008 to 0.0048 wt pet. Crystals of known ovientation were tested in tension in an Instron ma chine to determine the yield strength and to obsevue wheather a yield point occurred. Slowly cooled crystals or those given a solution heat treatment did not show a yield point. However, crystals that were aged following a solution treatment showed a yield point for all of the nitrogen contents studied. It was concluded that nitrogen caused the yield point by the Cottrell mechanism. NITROGEN has been shown to produce sharp yield points in single crystals of cadmium, zinc,2'3 ß-brass,4 and iron,5,6 as well as in polycrystalline iron7 and molybdenum.8,9 Since magnesium has a structure similar to zinc and cadmium, it seemed reasonable that magnesium should also exhibit a sharp yield point provided it contained sufficient nitrogen. Bobalek and Shrader10 reported a total nitrogen content of 0.002 to 0.0065 wt pct in com- mercial magnesium alloys, an amount well in excess of that required by theory. However. magnesium differs from cadmium and zinc in that it forms a stable nitride, Mg3N2, which has a standard free energy of formation of -95,480 cal per mole at 25" c." If rather than being in solid solution, the nitrogen were predominantly combined as the nitride, it could not act to produce a yield point. This type of behavior is the basis for the elimination of strain aging and a yield point in steel by the addition of strong nitride formers such as titanium,12 columbium,13 aluminum,14 vanadium,15 and boron.16,17 Thus, there appeared to be factors both favorable and unfavorable to the production by nitrogen of a sharp yield point in magnesium, and the purpose of this investigation was to determine the actual behavior of magnesium crystals containing known amounts of nitrogen.

Jan 1, 1960

By R. W. Raymond

THE question, what is the best proportion among weight, fall, and speed of stamps, is one which has not yet received thorough and systematic examination. In considering the economical application of stamping machinery, we meet, at the beginning, with serious difficulties in obtaining accurate data for comparison. The weight and fall of stamps vary as the shoes and dies wear out; and this may lead to a change of speed also. Moreover, defects in engines, boilers, or machinery for the transmission of power, may occasion serious losses, which cannot fairly be charged to the arrangements of the stamps proper. Again, the capacity of stamp-mills is directly dependent, in some degree, upon the nature and extent of discharge, fineness of screens, and other peculiarities of the battery. Finally, the hardness and tenacity of the rock crushed varies so much that comparisons between different localities cannot be implicitly trusted. The safest experiments are those made in the same mill, by changing first one and then another condition of working; but this is seldom possible for such conditions as weight and lift of stamps, and only within narrow limits for their speed. We may eliminate questions of friction, transmission, and generation of power, in the case of stamps, by measuring the power actually developed by their fall. Thus, the weight, multiplied into the fall in feet, and the number of drops per minute, gives us exactly the number of foot-pounds exerted by each stamp. Dividing by 33,000, the number of foot-pounds per minute in one-horse power, we have the horse-power per stamp, from which the effective power of the whole mill may be obtained. Dividing the amount of rock crushed daily by the effective horse-power, gives us the daily amount per horse-power; and this is the best measure that can be obtained for the effectiveness of the stamps. A complete discussion of the subject would require us to determine the exact influence of the discharge, etc., and the exact resistance offered by different classes of rocks, for both of which points the data are wanting. Professor J. D. Hague, in the third volume of the United States Geological Exploration of the Fortieth Parallel, gives a valuable

Jan 1, 1873

By M. Van Siclen

THE outstanding fact in connection with dust disease in the United States at present is the growing recognition of its seriousness by state officials and by the more progressive operators of mining, metallurgical and allied industrial plants. The same may perhaps be said of labor in some of its better organized centers, but the average independent non-union workman continues, .as of yore, to suffer the toll of disability and even of death from dust inhalation without realization of the source of his ill-being. Progress in the betterment of the handling of sufferers from dust disease and of the conditions creating dust hazards in mining and allied industries is pursuing a course similar to that of the now widespread campaign against accidents, in which the risk is more obvious, more severe, and was naturally recognized sooner. The coming on of dust disease is generally relatively slow and its immediate effects not infre-quently masked by or attributed to other diseases. Marked exceptions to this general rule have occurred in districts where the dust is particularly pernicious, such as the Rand and Joplin; yet such exceptions, unhappy in themselves, opened the eyes of medical men, and of those in other localities charged with the responsibility for the welfare of industry, to the much more widespread if less spectacular hazard existing from the inhalation of dust in all rock-excavating operations and all industrial operations creating inorganic dust, whether it be crushing and grinding, sand-blast-ing, granite-cutting, or what not. Advancement to date in the United States in prevention and treat-ment has been slow, yet the record shows that quantitative methods for determining the degree of hazard and means for decreasing it were being developed as far back as 25 years ago; and that more rapid progress may be looked for from now on. In 1908, in this country; F. L Hoffman?(1) discussed the mortality from consumption in dusty trades, especially brass foundries; and in 1913 E. R. Hayhurst(2) described the effects of inhalation

Jan 1, 1933