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By Albert R. Ledoux

In Great Britain all analytical chemists are styled assayers, but in the United states a slight distinction is made, assayers being considered those analytical chemists who have chiefly to do with the determination of the precious metals. There have grown up around the assayers of precious metals a number of customs and traditions which, as a rule, do not fetter American chemists when called upon to determine the composition or constituents of any samples submitted to them for analysis. In Great Britain, on the other hand, trade-customs even go to the extent of enforcing the employment of an admittedly erroneous atomic weight in certain alkali-determinations. If the American chemist is asked to determine the amount of lime in a water, potash in an alkali, or silica in an ore, the owner of the sample does not presume to suggest what method he shall employ, nor does he question his report on the ground that he should employ another method. But even in America it is different with the assayer. Unfortunately for the guild, as well as for those who have to base business operations on the reports of assayers, customs and traditions as well as divergent interests seek to circumscribe him in his choice of method and sometimes dictate how he shall perform his operations. This was true at one time of copper, which to-day in England is still determined by the so-called Cornish fire-assay, an attempt to imitate in the laboratory the various metallurgical operations in the smelting-works; but nowhere in this country is the assayer forced to employ any particular method for determining copper so long as his certificate indicates the true total percentage of copper in the sample. It is true that both buyers and sellers demand use of the electrolytic method, but only because it is the most accurate. In America the trade accepts the assayer's statement as final, and makes

Jan 1, 1895

By John K. Hammes

INTRODUCTION This introductory paper presents a description and definition of what the finance function is and what it specifically means for the mining industry. In its simplest terms, finance is, "management of money matters". As an area within the discipline of business administration it draws heavily on the related fields of economics and accounting, and to a lesser extent on marketing and production. MINING FINANCE DEFINED In preparing to write about what finance means to the mining industry, I asked a number of mining people the question, "What does mining finance mean to you?" Most responded that mining finance was "How a company borrowed money for mine development", and perhaps half those questioned included "raising equity" in the definition. It is not surprising that the mining industry concept of finance is the providing of funds needed for the objectives of the business, for that was once a view shared by authorities in the field of business administration. Further, it is certainly the area where much of the emphasis has been placed in the past ten to fifteen years as the industry struggled with the development of more remote and more refractory or lower-grade orebodies while profitability and internal cash flow were below expectations. No wonder project finance became such a popular topic. Twenty years ago it is probable that the emphasis would have been on mine valuation, for that subject was the area of finance then most often examined in industry publications. Papers concerning the pros and cons of payback, internal rate of return, and discounted cash flow appeared regularly. Let's examine the following situations, each the result of a financial decision: - Funding the exploration program in a developing country was accomplished by buying the next six-months budget needs in local currency. One week later the currency devalued 30 percent. If the purchase had been delayed or the local currency borrowed short term, a substantial saving would have been made in funding the program. - A major mining company borrows heavily to finance both expansion of its primary mining business and its entry into several new industry segments. When markets for all of the commodities it produces turn down for a prolonged period, there is concern over the adequacy of cashflow to cover debt service in addition to other company needs. The company's financial officers, however, had arranged very large committed credit facilities from numerous financial institutions which assured the availability of funds for several years. This enabled the company to implement a strategy to conserve cash, sell assets and survive until conditions improved. Further, short term suppliers of credit also were comfortable with the assurance that longer term credit was there to support them. -A medium size mining company financed several mines independently with limited obligations on the part of the parent company. The company decided to refinance the operations under one agreement. More flexible terms, lower interest cost and a longer tenor financing were achieved in return for assuming the risk as a direct obligor. - The exploration and development group of a large mining company proposes to develop a new mine in a country in which the company does not presently operate. When the investment is rejected they are advised that one reason was that the reinvestment assumption inherent in the discounted

Jan 1, 1985

By P. Chiotti, J. T. Mason

Metallographic, thermal, X-ray, and vapor-pressure data were employed in establishing the Ce-Zn phase diagram. Nine compounds and three eutectics were observed. The eutectic compositions in weight percent zinc and temperatures are 10 pct and 495"C, 37 pct and 795°C, and 56 pct and 810°C. Three of the compounds, CeZn, CeZnn, and CeZne.5, melt congru-ently at 825°, 87.505°, and 980°C, respectively; the other six compounds, CeZns, CeZns.67, CeZn4.5, CeZn5.25, CeZn,, and CeZnll, decompose peritectically at 820°, 840°, 870°, 885", 960°, and 795"C, respectively. The compound CeZn5.25 is an AB5 type with a small range of composition which lies on the zinc-rich side of the 1 to 5 stoichiometry. Zinc vapor-pressure data obtained by the dewpoint method were employed in calczilating the thermodynamic properties of both the liquid alloys and solid compounds. The data for the A critical review of the information available on the Ce-Zn system up to 1960 has been given by K. Gschneidner, Jr.' Of particular interest is the work by J. schramm2 who investigated the region between 55 and 100 wt pct Zn and reported a CeZn,, compound which decomposes peritectically at 785"C, a CeZn, compound which melts congruently at 972"C, and five temperature horizontals at 79@, 817", 840", liquid alloys were fitted to the relation from which the relation was obtained by integration. In these relations F XS is the excess partial molal free energy, N is atom fraction, and the constants c and d have the values c = (-22,000 + 7.0T) and d = 6171,000 + 74.0T). Relations for the standard free energy of formation for the solid compounds were derived from the data. At 973°K the enthalpy in kilocalories per gram-atom z)aries from —11.3 for CeZnz to —8.21 for CeZn~l and the free energy in the same units varies from —7.1 joy CeZn, to -3.82 for CeZn11. and 942°C in the region between 55 and 75 wt pct Zn. No attempt was made to identify other features of the system. I. Johnson and R. yonko3 used a fused-salt cell to measure the electromotive force between pure cerium and an alloy consisting of zinc-rich liquid in equilibrium with CeZnll. Solubility data for cerium in zinc has been reported by J. Knighton et u1 .4 Johnson and Yonko give the following equa-. tions for the mole fraction of cerium in zinc and the standard free energy of formation of CeZnll:

Jan 1, 1965

By R. T. Gallagher, C. G. Brennecke

This paper is the result of a research program entered into cooperatively by the General Reinsurance Corporation and Lehigh University in January 1944. The research program was instituted to find a more positive method to determine the presence of hazardous roof conditions in mining operations. The co-authors, together with Mr. R. D. Currie, Engineer for the General Reinsurance Corporation, started working on the project in January 1944, first undertaking a library search; second, a preliminary study based on some existing equipment; third, the design of new and more suitable equipment; and finally, the field testing of equipment and methods. PURPOSE Any study of the accident statistics of mining operations will disclose the rather startling fact that approximately 50 to 60 per cent of all fatal underground accidents in the anthracite and bituminous mines are caused by falls of roof and coal, the metal and nonmetal mines showing only a slightly smaller percentage. Advancements in safety engineering have produced definite results in the decrease of accidents due to blasting, haulage, electricity, and explosions but no such decrease is shown in those caused by falls

Jan 1, 1946

By Joseph L. Patrick

Geologic exploration, which has experienced an upward trend in the United States since 1962, continued with increasing activity through 1965. New, spectacular discoveries of recent years and continued questionable economic and political climates in many areas of the world have continued to focus the exploration attention of an increasing number of companies on the United States. Traditional geologic field methods are being bolstered by development of new methods, techniques and geophysical instruments. Reports from the states emphasize that successful exploration is dependent upon the combined effort of geochemistry, geophysics and geology, with high quality laboratory support of the field effort becoming increasingly necessary. PROGRAMS NOW UNDERWAY IN WEST During 1965 mineral exploration reached an all- time high in Nevada. Although examinations are being carried on throughout the State, much of the work is limited to two areas. The first area to attract recent exploration interest, initiated by discovery of the Carlin gold mine by Newmont Mining Corp., is an area of windows near the leading edge of the Roberts Mountains thrust fault in northeastern Nevada. Included in this area are the old camps of Mountain City, Battle Mountain, Cortez, Mineral Hill and Eureka. Major mining companies are using a combination of surface mapping, geochemistry, geophysics (largely induced potential surveys), following up with drilling. The second area of exploration is along the Walker Lane, a wide shear zone that parallels the Nevada-California boundary from Virginia City to Las Vegas. Activity has been intense in the Tonopah-Yerington area. Discovery of a large copper-iron deposit following an airborne magnetometer survey first focused recent attention on Walker Lane. Sixteen major companies are involved in exploration in the State.

Jan 2, 1966

By E. D. Williamson

DURING the wartime rush to prepare the glass necessary for the needs of our army and navy, the problem of the temperature control of the annealing kilns became most serious. The narrow limits of strain allowable (all the specifications called for less internal strain than the average of the previously used German glass) made necessary a very exact procedure and the methods had to be used on a much larger scale than theretofore. At the Charleroi plant of the Pittsburgh Plate Glass Co., the members of the staff of the Geophysical Laboratory, which was cooperating with the company, had occasion to study the methods available, and reached a number of conclusions (many of them by no means new except in their application) that may interest and assist those who have to meet similar problems in other fields. The following is a short account of the essential features of the system of temperature control evolved, along with a rather abridged statement of the reasons that led to the adoption or rejection of various schemes.

Jan 8, 1919

AMERICAN INSTITUTE OF MINING ENGINEERS 29 West 39th Street, New .York, N. Y. PROPOSAL FOR MEMBERSHIP Address Member is hereby proposed by the undersigned, as a Associate Junior Member of the American Institute of Mining Engineers. Signatures of .-' three Members or Associates. Place of birth Year of birth Education, when, where and how acquired, with degrees, if any. " A technical education is not requisite for membership. Dates Please give record of experience on following page with dates; for example, in the form used by "Who's Who In America" and similar publications.

Jan 7, 1917

By R. W. Shoenberger, J. D. Clendenin, W. L. McMorris, N. Schapiro, B. R. Kuchta, A. A. Terchick, R. J. Gray, J. G. Price

INTRODUCTION * The United States is fortunate in having enormous reserves of metallurgical-grade coals. Although these coals are better in quality and more accessible than most coals found throughout the rest of the world, the best grades of these coals are being depleted. Consequently, more efficient exploration tools and techniques, such as advanced methods of core drilling and logging, correlation by palynology,** stratigraphy, paleontology and petrography are being used to help assess the extent and quality of the remaining coal reserves. Exploration and assessment of new and existing coal properties become of utmost importance in determining (1) the economic justification for mining the coal, (2) the optimum design of the preparation plant and (3) the most effective use of the coal. Fortunately, the cost of mining coal has remained stable because of better mine planning, more efficient operations and increased mechanization of mining operations. However, increased mechanization raises the amount of impurities in the coal mined, and this requires more and better coal beneficiation to meet the more stringent quality requirements set by the market. Besides, mechanical miners also produce relatively fine coal and, to ensure maximum liberation of impurities, much of the coal presently being used must be crushed to a finer size prior to preparation. The bulk of all coals presently used in this country is mechanically cleaned, much of it at a lower specific gravity than in the past. This necessitates the use of new and improved processes and equipment for coal washing and recovery, such as heavy-medium cyclones and vessels, and froth flotation cells. However, because wet-cleaning processes are pre- dominant in the United States and fine coal retains large amounts of moisture, the increased production of cleaned fine coal accentuates the need for new or improved methods and equipment for dewatering and drying this coal. The larger amounts of coal being beneficiated and the use of new and improved beneficiation processes will aid in controlling and ultimately eliminating sources of pollution. Modem coal markets demand coals that meet rigid specifications. Most coals are purchased under contracts that specify moisture, ash, and sulfur contents, or heating value, depending upon the end use. There has also been a growing trend toward specifying other properties, including particle size and coking capability. These specifications may include not only the * Editor's note: Because of the numerous and varied contributions of the associate authors of this chapter, the text does not differentiate between sections prepared by each individual as has been done in other chapters. ** Palynology is the study of plant microfossils, especially spores, pollen, and other types of fossils not usually studied by paleontologists.

Jan 1, 1968

By Su Zhen

Based on the technical features of the Feng- huang-shan concentrator, the authors have designed a new scheme for optimal search and self-adaptive control in flotation process, in order to apply computer control to the concentrator. Hence, a plant test of optimal control in bulk flotation of copper and iron sulfides was successfully carried out. The control parameters are xanthate addition, pulp level, and amount of aeration, etc., in flotation cells. Two mathematical models of multiple parameters established by the authors were adapted and flotation efficiency was used as an objective function in the control.

Jan 1, 1984

By Sylvain Pirson

THE number of seismograph field crews employed in the active survey of potential oil territories is still on the increase, owing to the ever pending threat of a shortage in the supply of crude oil. It is to be expected that for years to come the seismograph will be responsible for discovering many new oil fields, both in wildcat territories and in deeper formations, and that the seismographic campaign will go on unabated. Yet improvements in instrumental design, in the field and interpreta-tive techniques, are brought about year after year, and lead to the reshooting of areas many times surveyed previously. Notwithstanding the experience gained by the past eight years of active work in reflection seismographic surveys, the results given by this method of mapping deep formations have in many instances been at variance with the information subsequently obtained by the drill. To overcome this shortcoming, geophysicists have used closer spacing of the shot points and closer control of the depth points. The method dis-cussed here is being used actively in the Mid-Continent region and endeav-ors to reduce the interpretation work to a mere mechanical technique, leaving as little as possible to the opinion of the interpreter.

Jan 1, 1937

By Walter A. English

The four papers making up this symposum have been prepared especially for those who have no knowledge of seismograph prospecting. To many people mathematics is a formidable subject, and many are discouraged from studying seismograph prospecting under the mistaken assumption that the mathematical requirements are severe. In the papers presented here there is not a single mathematical equation. We believe that considerable competence in dealing with some of the most important problems of this work can be attained without any mathematical training whatever. At the present time, there is a real need for interpretation of results by persons thoroughly competent to bring geologic experience and imagination to bear on data that are subject to multiple interpretation from a strictly physical viewpoint. Likewise, those charged with the responsibility of planning seismograph exploration campaigns would do well to become familiar with as much as possible of the technical aspests of the work. They would then be in better position to judge of its success in individual cases. It has often been said that the seismograph is a new structure-finding tool for the geologists to use. Using a tool and using its product are two different things. One does not use an automatic screw-threading machine when he buys a box of screws at the hardware store. Neither does the geologist

Jan 1, 1940

By Walter A. English

The four papers making up this symposum have been prepared especially for those who have no knowledge of seismograph prospecting. To many people mathematics is a formidable subject, and many are discouraged from studying seismograph prospecting under the mistaken assumption that the mathematical requirements are severe. In the papers presented here there is not a single mathematical equation. We believe that considerable competence in dealing with some of the most important problems of this work can be attained without any mathematical training whatever. At the present time, there is a real need for interpretation of results by persons thoroughly competent to bring geologic experience and imagination to bear on data that are subject to multiple interpretation from a strictly physical viewpoint. Likewise, those charged with the responsibility of planning seismograph exploration campaigns would do well to become familiar with as much as possible of the technical aspests of the work. They would then be in better position to judge of its success in individual cases. It has often been said that the seismograph is a new structure-finding tool for the geologists to use. Using a tool and using its product are two different things. One does not use an automatic screw-threading machine when he buys a box of screws at the hardware store. Neither does the geologist

Jan 1, 1940

By John M. Kelly

This report covers the development, exploratory drilling, and production of oil and gas in New Mexico during 1945. The statistical information was gathered from state regulatory agencies and other sources believed to be reliable; it is presented here in combined form for general information only, and the author assumes no responsibility for its accuracy or completeness.

Jan 1, 1946

By A. O. Bartell

Do you know that valuable clues to the geology and mineralization of a district can be found in a handful of sand from a stream bed draining the area? This handful of sand has a story to tell to those who have a little patience. The handful of sand may contain tiny specks of valuable minerals (gold, scheelite, cinnabar, chromite, tourmaline-to mention a few), that will lure you upstream with the hope of uncovering a new deposit. More practically, this handful of sand can indicate the type of rocks that are exposed by the drainage system. Any mineral that has a specific gravity of 3.5 or higher can be separated from soil by panning. Garnet and pyrite, for example, can indicate an outcrop of metamorphic rock. In one district where the writer prospected, small boat-shaped orthorhombic crystals of topaz always indicated the presence of andesite outcrops.

Jan 1, 1948

• Pellets of concentrated iron ore have been smelted in the blast furnace by Armco and the results proved satisfactory. Various percentages of pellet burdens were tried and it has been found that charges up to 70 pct pellets are workable. •In the reorganization of the Department of the Interior, two new assistant secretaries were appointed and the work divided between the four assistant secretaries. C. Girard Davidson will head a division of mineral resources including the Bureau of Mines, Geological Survey, Division of Oil and Gas and Division of Geography. •Germanium, one of the rarest of metals and a wartime strategic material, has been discovered almost in the shadow of the Capitol. The only catch is that the scattered nature of the deposits makes profitable recovery extremely doubtful. Nevertheless, experts have tabbed the concentration in the District of Columbia area the world's second richest known concentration of the element. • Cakes of mica, weighing up to 500 lb, have been formed at the Colorado School of Mines by a new "cool hearth" method. The process avoids use of crucibles and contains the molten mica in a basin of unmelted raw mixture from which the melt was derived. Crystallization takes place in this melting basin which forms a center pool surrounded by a solid cool mass of the unmelted raw mixture. • William 1. Baxter, of the International Economic Research Bureau, predicts a period of deflation because of war-essential restrictions on consumer credit and materials use. He stated; "the recent prosperity was based mainly on the sales boom in autos, homes, and household accessories." •Two subsidiaries of United States Steel have decided to build four new ships immediately to augment iron ore and limestone carrying capacity on the Great Lakes to meet demands created by the national defense emergency. •The Norfolk and Western Railway is making a complete change over to coal to drive its locomotives. •A national roster of scientific personnel similar to the one used in the last war will be established by the Office of Education, by agreement with the National Security Resources Board. The new unit, the National Scientific Register Project, will make studies of the Nation's scientific manpower supply and recommend steps to increase the numbers of skilled personnel where needed. •National Lead Co. will start construction immediately of new facilities at St. Louis, Mo., for production of titanium pigments for paints. Producers of titanium pigments have been under considerable pressure to meet all demands from paint manufacturers, particularly for titanium dioxide. •The basic criteria for deferment of reservists in civilian occupations are (1) the Department of Labor List of Critical Occupations, and (2) the Department of Commerce List of Essential Activities, both of which were announced Aug. 3. Fundamentally, the reservist deferred must be engaged in a critical occupation which is necessary to a highly essential activity, and he will be deferred only until he can be satisfactorily replaced in that occupation. A delay in call to active duty, it was emphasized, may not be considered as an indefinite exemption from military service.

Jan 9, 1950

By John M. Gallow

Discussion of the paper of JOHN M. CALLOW, presented at the New York meeting, February, 1916, and printed in Bulletin No. 108, December, 1915, pp. 2321 to 2339. R. H. RICHARDS, Boston, Mass.-I think there is one note which would be interesting to have recorded in connection with this paper, and that is another form of flotation machine. The Minerals. Separation machine has a vortex action, with a vertical shaft and a propeller. This new frother has been developed for the Copper Queen Co. at Bisbee, Ariz. It has a horizontal shaft and a paddle wheel for a frother. It has eight cells, I think, all connected underneath in one continuous tank, and the only separation of the cells is in the upper chambers where the froth is. When this paddle wheel goes around it throws out the froth and the sand goes to the bottom and drifts over from the first to the second cell, where it is paddled again, and comes out with its froth; the sand goes to the third cell where it is again beaten. In that way the sand is continually drifting toward the last cell, while each new froth remains in its own cell. You can see in the working of this machine just the same effect that you see in Callow's machine, i.e., the earlier cell has the darker or richer froth, and the latter has the lighter or poorer froth until you get to the farthest one-which has very little froth, and is very light. JOSEPH W. RICHARDS, So. Bethlehem, Pa.-Speaking from the metallurgical standpoint, it is quite desirable, in many cases, that the oil be removed from the concentrate in order to facilitate the metallurgical work, and I think attention should be directed to the desirability of removing from zinc sulphide concentrates the oil which interferes with their subsequent roasting. The value of the oil is not large; in Mr. Callow's plant, for instance, it would be $20 a day, and it may be possible that a process might be developed which, within the limits of the value of the oil, would remove it, and thus facilitate the metallurgical treatment. LEONARD WALDO, New York, ,N. Y.-The question came up about a year ago as to why-Mexican crude was not an admirable oil for flotation. I have never heard any satisfactory answer to the question. The Mexican crude has the peculiar property of comparative freedom from dangers of fire, a very great reluctance to part with its water, and a specific gravity almost identically the same as water.

Jan 5, 1916

By Harry L. Brown, James M. Dickinson, Philip E. Armstrong

The elastic stiffness coefficients of niobium have been rneaslrred from -150°C to over 650 C and ave in accord with the anomalous temperature dependence previously observed for Young's modulus. This unusual behavior has been shown to be the result of changes in the relative values of the shear elastic coefficients. The bulk modulus remained essentially constant over the temperature range studied, while changes in the shear coefficients produced a more nearly isotropic behavior as the temperature increased. A number of investigators have reported data on the temperature dependence of Young's modulus of polycrystalline niobium. The values cited for the room-temperature modulus ranged from 0.71 to 1.17 x 10" dynes-cm-' (10.3 to 17.0 x lo6 psi) and in each case the modulus was observed to decrease with increasing temperature. In our recent study,8 both polycrystalline and single-crystal samples of essentially strain-free high-purity niobium showed a Young's modulus whose temperature dependence as well as magnitude was strongly dependent on specimen orientation. This was shown to be the result of changes in the relative magnitude of the two shear moduli, C and C'. Young's modulus of polycrystalline samples with strong [110] textures and Young's modulus of single crystals whose orientations were away from the [loo] actually increased as much as 12 pct between room temperature and 1000°C. While studies on the residual effects of previous fabrication, thermal treatments, and impurity contents will probably resolve the problem of the widely differing Young's modulus values observed in polycrystalline niobium, a more complete description of the elastic properties requires an evaluation of the single-crystal elastic constants. A knowledge of these constants can provide a clearer picture of the nature of the temperature dependence, as well as establish a basis for predicting the modulus behavior of polycrystalline niobium, both in the randomly oriented condition and with various fabrication textures. The effects of residual strains on the elastic behavior then can be separated from orientation effects. EXPERIMENTAL METHOD Thin rod-resonance techniques were used to obtain both the Young's modulus and shear modulus of single-crystal specimens. The determination of these moduli as functions of the crystallographic orientation of the specimen axis provided sufficient information to permit calculation of the single-crystal elastic constants. The necessity for torsional as well as longitudinal measurements led to the design and assembly of a vertical-tube vacuum furnace incorporating probes for the simultaneous determination of both longitudinal

Jan 1, 1967

By M. J. Pool, P. J. Spencer, J. R. Guadagno

THE present work was carried out as part of a general program to study the magnitude and concentration dependence of exothermic heats of solution of various metals in liquid tin. Thermodynamic data for the Te-Sn system are very limited, particularly for dilute alloys. Indeed, apart from the prior heat of solution determinations of Pool,1 the only other published values are those of McAteer and seltz2 who carried out electromotive force measurements on solid alloys of compositions from 75 to 95 at. pct Te at temperatures between 543° and 668° K, of Colin and Dro-wart3 who made mass-spectrometric studies of the vapor in equilibrium with solid SnTe, and of Robinson and Bever4 who determined the heat of formation of SnTe by solution calorimetry. The present work thus provides further thermodynamic information for this system, specifically in a temperature range where the solubility of tellurium is very limited. The liquid metal solution calorimeter used in this investigation has been described previously.' No further discussion of its design or operation will therefore be given here. For each series of measurements a tin bath consisting of approximately 70 g of 99.99 pct pure Sn was carefully weighed out and inserted in the calorimeter which was maintained at the desired temperature to within ± 1/4°c. Tellurium, of 99.999 pct purity, was supplied by Atomergic Chemetals Co., a division of Gallard-Schlesinger Chemical Manufacturing Corp. Approximately 0.0006 to 0.001 g-atom specimens of tellurium were used for each experimental run and these were added to the calorimeter from a temperature of 273" K. Heat of solution values were calculated by analysis of a strip-chart recorder plot of the heat effect accompanying the solution of each sample in the tin bath. The heat capacity of the latter was determined at regular intervals during a series of tellurium drops by using pure tin or tungsten calibration samples, the heat contents of which were obtained from the standard compilation of Hultgren et al5 The composition of the bath was calculated after each drop from a knowledge of the weights of tin and tellurium added. Values of the heat of solution of tellurium at 725" and 775° K are listed in Table I together with the corresponding tellurium contents of the alloys. The data are also plotted as a function of tellurium concentration in Fig. 1, which includes the equivalent data obtained by pool' at 750° K. It can be seen that the heat of solution remains

Jan 1, 1969

By J. M. Hodge, H. M. Reichhold, R. D. Manning

The work reported in this paper represents the first of a series of investigations of the factors governing notch toughness in ferritic materials. This paper is concerned with two of these factors, namely, the effect of ferrite grain size, and the effect of an alloy content of 3.64 pct nickel. Every effort has been made to hold other variables constant in order to isolate the effects of these two. The compositions chosen for study were 0.02 pct carbon in order to eliminate the variable of carbide distribution, one steel being a plain carbon steel and the other alloyed with 3.64 pct nickel. Both steels were fully killed with silicon, without an aluminum addition, so that the variable of deoxidation practice was held constant. Finally, all samples were water quenched from 1200°F and tempered 24 hr at 300°F in order to hold the quench aging variable constant and to decrease the tendency for grain boundary carbide precipitation. The ferrite grain size was varied by heat treatment over the range of A.S.T.M. grain size numbers of about 2 to 6 in each steel so that the effect could be evaluated individually and the notch toughness of each steel could be compared at comparable ferrite grain sizes. Materials and Experimental Procedure MATERIALS The materials for this investigation were obtained from Battelle Memorial Institute as 250 Ib induction melts which were forged into 134 in. square bars and then rolled into 0.6 in. square bars. Both steels were deoxidized with silicon, the aluminum content being held to a minimum. Check analyses of these materials are shown in Table 1. HEAT TREATMENT FOR GRAIN SIZE The grain size was varied by varying both the cooling rate and the austeni- tizing temperatures. The heat treatments used and the corresponding grain size values are tabulated in Table 2. A semicontinuous network of grain boundary carbide was observed in the microstructure of both the plain carbon and nickel steels in the as rolled condition and an additional heat treatment was necessary to eliminate this variable. Therefore, all samples were water quenched from 1200°F and tempered 24 hr at 300°F as a final treatment before testing. This heat treatment served to eliminate to a great extent the grain boundary carbide network and to hold the quench aging effect constant. IMPACT TESTING Standard keyhole Charpy impact tests were machmed after heat treatment. A bath of acetone and dry ice was used for refrigeration of the samples down to temperatures of —94°F (—70°C) and a bath of either methyl-cyclohexane or isopentane, cooled by

Jan 1, 1950

By Charles Berry

Conventional and nonconventional insurance is examined from the point of view of a financier of a major mining and minerals project. The paper reviews the elements of a conventional insurance program; explains why such a program is not fully responsive to the project financier's needs; examines some of the new insurance coverages that can supplement a traditional program; and emphasises that these insurance markets are still in the early stages of their development with consequent effects on capacity (insured amount) and to some extent price (insurance premium).

Jan 1, 1985