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On the following pages are abstracts of papers published by the Institute during the year 1936 as TECHNICAL PUBLICATIONS and CONTRIBUTIONS, papers in bound volumes appearing for the first time, and papers in MINING AND METALLURGY For abstracts of papers that appeared in bound volumes in 1936 but that were published as TECHNICAL PUBLICATIONS in 1935, see the YEAR BOOK dated January 1936.

Jan 1, 1937

By B. Chalmers, L. Bäckerud

The growth temperature of dendrite tips has been measured in a binary alloy system, Al-Cu, as a function of rate of formation of solid phase. Metallographic examination has rerealed the dendritic structure dereloped during different stages of the freezing process and factors influencing the undercooling, such as solute buildup, surface tension, and kinetic effects, have been estimated. Practical implications of the results are discussed. THE development of a dendritic growth pattern during the solidification of metals and alloys has an influence at least equal to that of grain size on the properties of the casting or ingot being produced. and consequently much interest has been devoted to the study of this phenomenon. A review of the knowledge gathered up to 1964 has been given by Chalmers.' Among recent publications in the area the works of Jackson et al 2 and Flemings and his coworkers3,4 are of special interest. This work is an experimental study of the factors which influence the development of a dendritic pattern during the solidification of a typical binary alloy system, A1-Cu, when there is no heat source in the liquid. This means that the temperature and the temperature gradient are controlled by the heat extraction from and latent heat evolved by the growing crystals. EXPERIMENTAL PROCEDURE Samples were prepared from a master alloy made up of aluminum, 99.995 pct, and copper. 99.99 pct, of the concentrations given below and of sufficient size to fill cylindrical graphite molds of 35 mm ID and 35 mm height. Bottom. wall. and lid of the graphite molds were all of 6 mm thickness, Fig. 1. Thin ceramic thermocouple shields could be introduced at different positions in the sample through holes in the lid. The assembly was heated in a small vertical resistance furnace to a suitable temperature. 700° to 720°C. which is well above the melting point of the sample. It was thereafter taken out of the furnace and chilled at selected rates, and the temperature changes in the sample were recorded. For high sensitivity in the temperature recordings, a reference thermocouple was held in a solidifying pure aluminum melt. which was very well insulated and therefore was at a constant temperature. 660°C, for nearly half an hour. The thermocouples were connected so that the difference voltage was fed into the recorder of which the most sensitive range was 1 mV. Temperature variations could be read to within 0.l°C. The thermocouples used were of the Chromel-Alumel type (28- or 38-gage wires) and the recorder a two-pen Moseley strip chart recorder. The different rates of chilling were obtained in the following way. a) The graphite crucible was wrapped in one or two layers of an insulating. feltlike material (Fiberfrax paper from the Carborundum Co.). The drop in temperature per unit time after complete solidification could thereby be varied from 8" to 18°C per min. This corresponds to a rate of heat extraction in the given samples from 0.08 to 0.17 cal cm-' sec-I. 6) The bare graphite mold was placed free on a piece of firebrick. The measured temperature drop was around 50°C per min (-0.5 cal cm-" ' sec- I). c) By blowing compressed air through a tube with many holes surrounding the mold in a ring shape. the rate of heat transfer could be raised to 150' to 200°C per min (-1.7 cal cm-3 sec- I). d) Cooling rates around 1000 C per mill (-9.4 cal cm-3 sec-l) were obtained by substituting the air in the device used in c by water. The range of cooling rates used in these experiments correspond to technical casting processes from slow solidification as obtained in sand molds to very rapid freezing which occurs in some continuous casting and welding processes. EXPERIMENTAL RESULTS The A1-Cu system was chosen for the experiments: the relevant part of the phase diagram is reproduced in Fig. 2. Observation of the Center Temperature. When a thermocouple is inserted in the center of the melt. the type of cooling curves obtained at slow solidification rates differs little from numerous published curves from similar systems. and the solidification pattern

Jan 1, 1970

By Philip B. Bucky

[ ] FOREWORD THIS symposium brings together points of view, experiences and ideas on rock bursts from a goodly portion of the globe. Some conceptions, particularly those regarding the necessity of depth, have been fairly well shattered, as we find that they are present in the water tunnels of New York, on the surface at marble quarries in Vermont, and in the coal mines of the United States, as well as in the deep mines of the South African and Kolar gold fields, and in the nickel, copper and gold mines of Canada. Their occurrence under such a variety of conditions is, therefore, a challenge,

Jan 1, 1942

By C. Scala, M. Gondouin

Published laboratory data have established that very significant streaming potentials can exist across mud cakes subjected to pressure differentials such as exist between a mud column and formation fluids. Since shale is similar in kind and in properties to a well-formed mud cake, it appeared possible that streaming potentials might also arise across shales. A practical consequence would be that the streaming potential contribution to the SP would be smaller than might otherwise be assumed since the SP is measured with respect to the "shale bare line". The resultant contribution would be the difference between the streaming potential across the shale and that across the mud cake. In order to investigate this possibility, a laboratory apparatus was devised for measuring streaming potentials under pressure conditions normally encountered in wells. Reported data on streaming potentids across mud cakes were verified. More important, appreciable streaming potentials were found across shale samples. As in the case of mud cakes, the shale potentials varied with the concentration and nature of the impregnating electrolyte. Dependence on pressure was In a different rela-tion than that for mud cakes, possibly because of the lower compressibility of shales. The differences in streaming potentials between the shales md mud cakes were generally small, although they might vary considerably in practice depending on the relative electro-kinetic properties of the particular shale-mud cuke combination. A "poorly eflective" shale with a "very eflec-tive mud cake" would produce the largest negative addition to the electrochemical component of the SP. Results of field experiments with pressurized wells were considered in the light of the laboratory results. INTRODUCTION Field experiments wherein the pressure of the mud column in a borehole was varied have often indicated the presence of a streaming potential, but its magnitude was not easily predictable and its sign sometimes changed from one formation to another in the same well.' In the interpretation of SP logs from standard surveys, nevertheless, the correct value of R,, is very frequently obtained, within the limits of field accuracy, using only the simple electrochemical expression of the SP provided that proper corrections are made for bed thickness, ion activity, etc.' Accordingly, it was apparent that the streaming potential component of the SP in a borehole was considerably more complex than commonly assumed and clarification was indeed necessary The close similarity in nature and constitution of a shale to a well-compacted mud cake suggested that a streaming potential might also exist across shales as pointed out by M. P. Tixier in 1953 and as recently emphasized by Wyllie." e practical consequence would be that the streaming potential across the mud cake would be canceled, at least in part, on electrical logs since the SP is recorded with respect to the shale potential as a base line. This appeared to be a plausible explanation for many of the effects observed but no supporting data were available. In 1955 preliminary experiments at low pressures were conducted in our laboratories which supported the hypothesis of the shale streaming potential and formed the basis for later studies at borehole pressures.* EARLY LOW PRESSURE EXPERIMENTS The early experiments were conducted primarily to determine the possibility of a streaming potential across shales. The shale used was a compact type designated as No. 7 from Reagan County, Tex. (Permian). Cut samples were saturated for over one month in .2 to 2.0-N NaCl solutions. In order to eliminate all electrode polarization effects, a dynamic method was used. A transient pressure of about 1 atm was applied across

By H. Y. Bassett

THIS paper attempts to show the various major operations used in nonferrous tube mills and does not necessarily represent the current practices at the two plants of the Wolverine Tube Div., of Calumet and Hecla Consolidated Copper Co. Inc. The operations now utilized in the production of tubing are quite varied and show the continual interest and advance metallurgically and mechanically to produce the best quality at the lowest cost. Naturally, any advance or lowering of cost is dependent on large production runs, which mean longer machine running time with maximum worker productivity. Standardization of tube sizes and elimination of unnecessary alloys are therefore very necessary, otherwise the development of costly new production machines would be of little benefit to the consumer as a whole. It should be noted that in such a short presentation it is impossible to describe in any detail the major operations. The short descriptions, it is hoped, will enable all who are interested to obtain a general idea of present, day practices in the copper tube producing field. Fig. I is a flowchart or sequence of operations showing the steps usually employed in tube production. RAW MATERIALS Quality starts with the raw material, and it is absolutely necessary that raw material be controlled and held to rigid specifications. Little need be said, however, regarding the raw materials for the casting of bars or billets, as the material always is purchased and checked against the various governing A.S.T.M. specifications. CASTING Casting, as is indicated in Fig. I, is quite varied and for convenience can be classified into two groups: The casting of solid billets, and the casting of hollow tubes, each of which is the base for subsequent operations. In the melting of the raw materials various types of furnaces are used, and the selection of any one is dependent on many factors outside the scope of this paper. However, as of general interest, a short description will be made of each. Induction Furnace (Low Frequency) This is popular in the melting of copper-base alloys, Fig. 2. In the induction furnace the principle of an inefficient transformer is used for the production of the necessary melting heat. The primary coil is.arranged around a transformer core made of high permeability silicon steel sheet. The secondary circuit is through a melting channel around the primary coil and opens into a hearth which contains the main charge. The heat is generated only in the melting channel, but because of the stirring action there is a constant flow of metal around the channel, which when mixing with the charge causes very rapid melting. The volatilization losses are very low as the furnace atmosphere above the charge is heated only by the heat from the melting metal. The stirring action, however, makes the use of any slag cover difficult. Such furnaces- must be started with molten

Jan 1, 1951

By W. B. Boggs, J. N. Anderson

An account of the operation of the Noranda smelter covering the period from December, 1927, when the smelter started, until December, 1929, was given in a paper published by the Canadian Institute of Mining and Metallurgy early in 1930.' The object of the present paper is to review matters of interest in the original paper and to describe the present construction and operation of the smelter, with particular reference to the reverberatory-furnace practice. The Noranda smelter was built by Noranda Mines, Ltd., from the designs of A. E. Wheeler, consulting metallurgist of New York, for the reduction of ores and concentrates from the Horne mine and to treat, on a custom basis, ores and concentrates from other mines in the Rouyn district. The smelter is at Noranda, about 330 miles directly north of Toronto. Construction work was started in June, 1926, and copper was first produced in December, 1927. The smelter was built throughout as two duplicate units, each with a rated capacity of 500 tons of ore per day. Operations were started with one unit and after several months it was found that one unit alone could smelt 1000 tons of ore a day. At that time there was only one hoisting shaft, No. 3, and its hoisting capacity and the capacity of the original crushing plant were insufficient to supply ore for the two units at the increased tonnage. Accordingly No. 4 shaft was sunk and a new crushing plant provided to handle the ore hoisted there. Operating two units at capacity also required the installation of two more converters to treat the additional quantity of matte produced. This work was completed in the latter part of November, 1929, and since then both smelter units have been operating continuously. In 1928, a mill to treat 500 tons a day of concentrating ore was completed. Since then the concentrator capacity has been increased twice, and at present 2000 tons a day of ore are being concentrated. The layout of the surface plant of the mine, concentrator and smelter is shown in Fig. 1 and the general plan in Fig. 2. The smelter is shown in more detail in Fig. 3. The original hoisting shaft, No. 3, is now used only for handling men, supplies and waste rock, and the original crushing

Jan 1, 1934

By Arthur F. Taggart

Some years ago, A. M. Gaudin and one of the authors published a paper showing removal of tar acids from solution by sulfides preferentially as compared to gangues (specifically by galena as compared to quartz).' The underlying phenomenon was classed as adsorption, and the paper went on to develop the general thesis that so far as water-soluble frothing and collecting agents in flotation are concerned, the phenomenon of adsorption is one of controlling importance. Adsorption was defined in that paper as "a process of rearrangement of a system, which results in establishing a difference in concentration, as between the interfacial layers and the bulk of the phases, of a substance or substances initially uniformly dispersed in one or several of the phases." The paper went on to develop the relation between adsorption and surface cnergy according to Gibbs' equation (which may be thrown into the form U/c = KdT/dc, where U = excess concentration in surface layer, c = concentration, T = surface tension, and K is a constant), and pointed out that, according to this equation, degree of adsorption and change in surface tension vary directly. The present paper offers a somewhat different definition for the term adsorption; and sets up, in sweeping terms, the generalization that simple chemical reaction underlies the functioning of the flotation reagents which control mineral collection, when these reagents are soluble in and act from solution in the water of the pulp. Adsorption According to the modified definition, adsorption means concentration at an interface between different phases in a heterogeneous system (thus far the definition runs as before), by the action of some mechanism, of which nothing is properly implied in the word, and concerning which the user of the word is probably in entire ignorance. Thus defined,

Jan 1, 1930

LIST OF MEMBERS AND ASSOCIATES ARRANGED ACCORDING TO STATES AND TOWNS. ALABAMA. Aldrich, Aldrich, W. F. Anniston, Noble, A. E Bessemer, Fergusson, V. Bir¬mingham, Aldrich, T. H., Jr, Bowron, C. E, Bowron, J., Davis, F H, Dimmick, F. D., Hillman, Ludwig, C. P., McCarthy, M. E, McCormack, G B., McCrery, Ramsay, E, Shook, A. M. Ensley, McDonald, S., Shook, J. W. Gadsden, Lee, R. H., Jr. Gannts Quarry, Hiller, E Helena, Squire, J. Huntsvalle, Moss Le¬high, Toulmin. Ozmoor, Greenamyer, A. G. Rock Run, Garvin, J M. Selma, Saylor, B. F. A. Sheffield, Miller, D, I. Tuscaloosa, Lodge, J. Woodward, Wood¬ward, A. H. ALASKA Coppermount, Wiswell, H. J. Douglas Island, Macdonald, J Ellamar, Stevens, B. Fairbanks, Hamilton, A L Haines, Le Wald, E A. Jualin, Hoggatt, W. B. Juneau, Denby, Hampton, W. H , Thane, B L , Whipple, J. R. Ketchikan, Bar¬ber, J C , Parker, J. L., Reid, G D Nome, Garfield, C D. Snettwham, Tisdale. Teller, Hirshberg, M. R. Treadwell Caty, Kinzie, Stow, H. P. Valdez, Esterly, G. M, Hazelet.

Jan 1, 1910

By C. Dirksen

This study investigates whether oxygen consumption during segregated forward combustion may be affected by natural convection. Linear theory indicates that thermal instability occurs in a horizontal porous medium when the modified Rayleigh number N 'Ra exceeds a critical value of about 40. Most experimental results, including those described here, indicate this value to be about an order of magnitude smaller. N ', is derived from "differential similarity" and the proper time scale factor is also obtained. The critical value of N'ra for a horizontal, water-saturated porous medium at atmospheric pressure subjected to a uertical temperature gradient was found to be about 3.0. The ambiguity in the value of N'R, arising when fluid properties cannot be assumed constant is indicated. Natural convection was observed for oblique systems below N 'Ra , while simultaneous horizontal flow did not affect N Racrit. The expected range of values for the various parameters pertaining to segregated forward combustion is indicated and the corresponding values of N 'Ra calculated. Only under very favorable conditions, such as high permeability, high pressure and low top temperature, can the critical value of N 'R, be exceeded. Thickness of the convection layer should not become too large, since the time required to obtain significant mixing is proportional to the square of the thickness. For an oblique combustion frant the conditions for significant mixing may be less strenuous. LNTRODUCTION Laboratory1,2 and field314 experiments have shown that a markedly upgraded oil can be produced by in situ forward combustion. Under certain conditions injected air may move through a high permeability, gas-saturated channel over the oil-saturated layer, while combustion takes place, exclusively, at the horizontal interface (Fig. 1). Such a channel may be a natural gas cap, or it may result from a forward combustion process in which injected air and combustion gases fingered through the top of the formation, causing a premature breakthrough at the production well. In this particular case of segregated forward combustion, the air stream moves parallel to the combustion front. Molecular diffusion and transverse mechanical dispersion will be insufficient to cause all the oxygen in the air stream to reach the combustion front. When the oxygen in the air stream is not completely consumed in the combustion process, it will reach the production well and create a serious fire hazard. In addition, the reduced efficiency may make the process economically unprofitable while also serious corrosion problems may be experienced in the production we11.3 This undesirable situation should, therefore, be prevented. However, in a situation as depicted in Fig. 1, an unstable temperature gradient exists in the gas phase. The combustion is taking place at the lower boundary at a nearly constant temperature that may be anywhere from 600 to 1,200F, depending on the conditions. The upper boundary of the gas phase is overlying, impermeable rock; its temperature might be around 100F, but may increase to 300F or higher due to conduction and convection as the combustion process continues. This represents a steep temperature gradient and it is conceivable that under those conditions free or natural convection will take place in the gas

Jan 1, 1967

By Carmine D. &apos, Lemuel Tarshis, Joel Hirschhorn, Antonio

Vapor-deposited nickel films in the thickness range 700 to 4360A were tested in uniaxial tension utilizing a microtester designed specifically for this study. Contrary to the findings of some investigators, a definite thickness-strength relationship was observed below 3000 A with a four-to sevenfold increase in strength over that of bulk nickel. The films were characterized by high elastic strains and little plasticity. On the basis of these and other reported data, it is suggested that the high strength level in metal films is related to the manner in which they are produced. Vapor deposition, owing to its severe quenching effect. is believed to promote the formation of point defects which inhibit dislocation movement. IN recent years it has been reported that metals, when in the form of thin films, exhibit extraordinarily high strengths. The data published to date have been primarily concerned with silver and gold because of the ease with which these metals can be vapor-deposited and their high resistance to surface oxidation. Previous investigations into the mechanical strength of thin films has uncovered an apparent dichotomy of view on film behavior. Beams and his co-workers have reported a definite dependence of strength on film thickness. Other workers,"-'6 however, in separate studies on the strength of poly crystalline and single-crystal films have found no such thickness-strength relationship. The study of thin-film strength is extremely difficult because of the many variables associated with film preparation, handling, and testing. Moreover, the manner of test employed by different investigators has varied quite radically, ranging from simple uniaxial-tension to biaxial-bulge testing. The work reported herein was conducted in order to determine the mechanical behavior of a structural metal when in the form of a vacuum-deposited thin film and to gain some insight into the reasons for the high strengths exhibited by metals having such a con- figuration. In this study a method of test was chosen which would yield results which are easily interpreted and lend themselves to comparison with properties of the same material in bulk form. Moreover, specimen-preparation parameters and film-handling techniques are set forth so that other investigators can properly compare their findings with ours. EXPERIMENTAL PROCEDURES A) Film Preparation. Vacuum deposition was performed in an 18 by 30 in. bell jar using a standard New York Air Brake Co. vacuum station with a 6-in. oil-diffusion pump. Before evaporation the system was pumped to a pressure of less than 2 x 10"5 torr. A shield was employed to protect the substrates from the emission of contaminants during the critical melting and outgassing of the evaporant. The source consisted of from one to six filaments (0.020 in. diam). The length of each filament was about 5 in. and was placed 6 to 8 1/2 in. from the substrate in such a manner that the substrate face was at 90 deg incidence with respect to the evaporant beam. The temperature of the source was 2000"~ during evaporation. The films were deposited onto a substrate arrangement which was composed of four basic components, that is: 1) a 3 by 1 in. glass slide; 2) a 22-mm sq micro cover glass on 1); 3) a 22 by 50 mm micro cover glass coated with collodion on 1); and 4) a stainless-steel sheet mask containing twelve rectangular openings of 1-mm and 2-mm widths and lengths of 5 mm laid over 3). Thus, test specimens of 1-mm and 2-mm widths are deposited onto a collodion substrate which precludes epitaxial effects in the specirnens. 17-le The rectangular cover glass and square cover glass were positioned in such a manner that a strip of film would be evaporated along the length and across the width of the large glass slide. This boundary of evaporated film was used to determine the film thickness by multiple-beam interferometry. The square cover glass was used for X-ray and chemical analyses. Thickness of the deposits was varied by changing the number of filaments used (one to six). The duration of evaporation was 30 sec for each filamgnt which resulted in a deposition rate of 8 to 20A per sec. Evaporations were all performed at room temperature; however, radiant heat from the source raised the substrate temperature to 40" to 60°C. All substrates were cleaned by ultrasonic agitation in a solution of spectranalyzed isopropyl alcohol. Collodion was deposited on the micro cover glass by immersion in solution of collodion in amyl acetate. B) Thickness Control and Measurement. Film

Jan 1, 1963

APPROXIMATELY 90 per cent of the steel that is melted and refined in the United States and poured into ingots is made in basic open-hearth furnaces, as shown in Table 1-1. The annual ingot capacity of the steel industry reported January 1, 1950, by the American Iron and Steel Institute3* was 99,040,160 tons, of which the basic open-hearth process accounted for 85,896,580 tons, 86.7 per cent of the .total. The capacity of the individual furnaces varies over a wide range, a large majority falling within limits of 50 to 200 tons (Fig 1-1). Most of the units constructed [ ] since 1942 are in the larger size groups, between 175 and 225 tons capacity.

Jan 1, 1964

Aalde, Kaare. ('40) Gen'I Del., Bisbee. Ariz. Aase, Glenn D., ('40) Univ. of North Dakota. Grand Forks. N. D. Abadesco, Enrique A., ('39) College of Engrg.. Univ. of the Philippines. Manila, P. I. Abbott. John L., ('40) Colorado School of Mines. Golden. Colo. Abdul-Ahad, A., ('39) Montana School of Mines. Residence Hall, Butte. Mont. Abreu, Ovidio M., ('38) Univ. of Nevada, Reno, Nev. Acomb, Allen. ('41) Louisiana State Univ., Box 1970, University. La. Acosta S., Gonzalo. ('40) Univ. of Texas, Univ. Sta., Box 1785. Austin, Tex. Adam, Howard W., ('41) Montana School of Mines. Butte, Mont. Adams, Albert, ('381 New Mexico School of Mines, Socorro. N. M. Adams. Charles W., ('39) Michigan College of Min. & Tech., Houghton, Mich. Adams. H. Travis, ('39) 316 South -5th St., Bur¬bank. Calif. Adams, Jack L., ('39) Univ. of Oklahoma, Nor¬man. Okla. Adams. John W., ('41) Colorado School of Mines, Golden. Colo. Adams. Lewis J.. ('39) 402 Del Mar Blvd., Corpus Christi, Tex. Adams, Rob L., ('40) Agricultural & Mech. Col¬ lege of Texas. Box 600, College Sta., Tex. Adamson. Charles R., ('41) Univ. of Utah, Salt Lake City. Utah.

Jan 1, 1941

By Paul A. Filteau

Asbestos ranks among the leading minerals produced in Canada. It is also mined in Russia, Rhodesia, South Africa, Cyprus, Italy, the U.S.A., Japan, China and several other countries. The most abundant variety, chrysotile, and also the most valuable form of asbestos produced, makes up 90% of the world's supply. In Canada, chrysotile is found in the provinces of British Columbia, Ontario, Newfoundland as well as in Quebec, the latter accounting for almost 90% of all the fibre produced in this country. A number of developments emerging this year could make 1968 a record production and export year for Canada's asbestos mining industry. Asbestos fibre consumption in increasing in the U.S., Canada, up 10% to date this year, Japan and in Latin America. Demand in Western Europe is again on the upswing, following a cut-back last year. As a result, shipments from Canadian mines for the first eight months of this year reached some 916,968 tons versus 873,402 in 1967, an increase of 43,566 tons or 5%. Indications are that Canadian asbestos production will for the first time ever top 1.5 million tons in 1968.

Jan 1, 1969

By R. L. Fleischer, B. Chalmers

In order to observe size effects associated with a grain boundary, aluminum single crystals and bicrystals of various cross-sectional dimensions were deformed in tension. Typical stress-strain curves are presented in conjunction with measurements of the effects of changes in crystal dimensions. Some effects of the growth rate used in preparation of crystals are also described. It is indicated that the macroscopic constraints at a grain boundary are responsible for the most prominent grain-boundary effect, the production of multiple slip. Two measurements of the width of the region of double slip are in agreement. It is concluded that the yield stress of aluminum is affected markedly by the inherent oxide coating. THE general problem to be examined is that of dimensional effects in the plastic deformation of metal crystals. These effects will be termed "size effects" and are here defined as follows: A size effect occurs in a series of crystals if their plastic-deformation properties are a function of crystal dimensions. Clearly then size effects depend on the nature of the boundary conditions imposed on the crystal. Crystal boundaries can be of three types: interphase, inter-crystalline, and free surface. Such deformation effects as are caused by distribution of phases, grain size, lineage structure, and single crystal external geometry are specific types of size effects. This discussion will be confined primarily to grain-boundary and single-crystal size effects, though in practice most "single crystals" not only have a number of small angle boundaries but also have one or more surface phases, so that the boundary conditions appropriate to a free surface do not necessarily apply. Hence, to this extent interphase size effects will be considered. The question of size effects associated with grain boundaries (called here intercrystalline size effects)

Jan 1, 1959

By Herbert Clark Hoover, Lou Henry Hoover

DIFFERENT methods of parting gold from silver, and, on the other hand, silver from gold, were discussed in the last book; also the separation of copper from the latter and further, of lead from gold as well as from silver ; and, lastly, the methods for refining the two precious metals. Now I will speak of the methods by which silver must be separated from copper, and likewise from iron.1 The officina, or the building necessary for the purposes and use of those who separate silver from copper, is constructed in this manner. First, four long walls are built, of which the first, which is parallel with the bank of a stream, and the second, are both two hundred and sixty-four feet long. The second, however, stops at one hundred and fifty-one feet, and after, as it were, a break for a length of twenty-four feet, it continues again until it is of a length equal to the first wall. The third wall is one hundred and twenty feet long, starting at a point opposite the sixty-seventh foot of the other walls, and reaching to their one hundred and eighty-sixth foot.

Jan 1, 1950

By Russell A. Carter

Although significant phosphate mining activity has occurred in four western states-Idaho, Montana, Utah, and Wyoming-southeastern Idaho contains the largest, most easily mineable reserves, and mining has focused there. More than half of the western phosphate field's economic reserves are within a 32 x 96-km (20 x 60-mile) rectangle bounded by Montpelier, Idaho, on the south, Soda Springs on the west, and Grays Lake on the east. A large amount of this land lies within the boundaries of the Caribou National Forest.

Jan 1, 1978

By Harry A. Lipsitt, Douglas Y. Wang

A fatigue study in completely reversed axial tension-compression has been perforried on high-purity titanium and on three high-purity alloys of titanium. The alloys each contain approxi7nately 0.75 at. pct of a single interstitial element; carbon, nitrogen, and oxygen, respectivley. The results corroborate a previously published theory which proposed that strain aging under alternating stress was responsible for the fatigue limit behavior of certain alloys. The present data indicate that in these alloys an increasing strain-talline aging effect under alternating stress is provided by oxygen, carbon, and nitrogen, respectively. CURRENT research on the nature of the fatigue limit in metals suggests that the presence of a fatigue limit in metallic materials is a manifestation of strain aging that occurs under alternating stress.lm5 A comprehensive theoretical model based on the above hypothesis has been developed to explain the existence of a fatigue limit.' This model also provides increased insight into several other fatigue phenomena as under stressing, overstressing, and coaxing effects. The theory, as well, provides equal understanding for those cases where no real fatigue limit is observed. Briefly, this theory assumes that the S-N curve for a pure metal is a smooth function of the applied stress, and the effect of adding an element that is soluble (or forms a precipitate) in the pure metal is simply to shift the S-N curve to the right. If the added element confers the power to strain age, the result is a further shift of the S-N curve, this time upward and to the right. Since strain aging is not expected to be a strong function of stress, and since damage per cycle is known to be quite stress dependent, it is to be expected that there will be some limiting lower stress at which the strengthening due to strain aging will balance the damage due to crack propagation. This stress is the fatigue limit. The position of the fatigue-limit knee was thought to be a function of the magnitude of the strain-aging effect on both the finite and infinite life portions of the S-N curve. Although the strain aging hypothesis seems to be reasonably valid for bcc materials,2'6 it needed to be tested for both fcc and cph metals. This report is the first of a series concerning the fatigue-limit behavior of titanium with varying amounts of the interstitial solutes (C, N,, and 4) that are known to cause static strain aging in titanium. Yield-point effects have been reported for polycrys-talline high-purity titanium alloys containing either carbon, nitrogen, or oxygen.7'9 These effects were observed at testing temperatures in the range 100 to 300'. In addition yield-point and strain-aging effects have been reported for single crystals of titanium containing 0.1 wt pct C plus N.' These yield points were observed over a wide temperature range, but no room-temperature aging occurred. Aging at 180' was required to cause the return of the yield point. The magnitude of the yield phenomena in titanium containing interstitials is not expected to be as large as is observed in bcc metals because of several factors. Titanium has a very high chemical affinity for oxygen and nitrogen. The thermodynamic stability of solutions of oxygen or nitrogen in titanium is recognized. Lattice parameter measurements of titanium containing arbon, oxygen,1° or nitrogen" show that the "c" parameter is expanded more than the "a" parameter, but that up to about 2 wt pct this results in an insignificant change of the axial ratio 'c/a." Ehrlich" has shown that the sites occupied by interstitial atoms in titanium are spherically symmetrical and therefore a lattice expansion, at a constant c/a ratio, results in a simple dilation of the interstitial site. Such a dilation involving no shear has been shown to react only with edge components of dislocations.13 This causes only a weak pinning action. Shear stresses would be anticipated locally when only one of the two interstitial positions was occupied. The carbon atom will cause a symmetrical distortion of the lattice whereas the oxygen and nitrogen atoms have, in addition, the previously mentioned chemical affinity of titanium for these elements. These factors will result in a considerably smaller reduction of free energy upon the association of interstitial atoms with dislocations, and therefore a much weaker pinning than has been observed for the bcc metals. These considerations would lead to the hypothesis that of the interstitial elements considered here carbon would cause the strongest pinning effect in titanium where the amount of interstitial in solution is constant. This hypothesis will be borne out in the analysis of the present results.

Jan 1, 1962

By F. J. Plecity, J. T. Michalak, W. C. Leslie

Isothermal recrystallization and grain growth in zone- and vacuum-melted irons and Fe-Mn alloys, up to 0.60 pct Mn, were studied in the range 480° to 650° C, after 60 pct cold reduction. In initial stages, rate of grain growth and rate of recrystallization of iron decrease with time. The recrystallization is typical of a growth-controlled process, and rate of growth is determined by the extent of recovery. Mn decreases rates of growth and of recrystallizatzon. The recrystallization process changes at about 0.30 pct Mn and nucleation may become time-depetzdet~t. In recent years, considerable effort has been expended in determining the effects of solute elements on recrystallization and boundary migration in fcc metals. The results have indicated that the effects produced by single solute additions are dependent upon both the element added and its concentration.'-' In contrast, there have been very few attempts to determine the characteristics of recrystallization and boundary migration in high-purity bcc metals, especially after heavy deformation, and the effects thereon of single solute elements.9-11 This study was undertaken to determine the recrystallization characteristics of various "high-purity" irons and the effects of manganese additions at two levels of base purity. It was hoped that the information obtained would improve our understanding of the recrystallization of pure metals and aid in formulating a theory for the effect of solute elements. The interest was not entirely academic, for the annealing of low-carbon steels, which is of very great commercial importance, is but poorly understood. MATERIALS The compositions of the irons and iron-manganese alloys used are listed in Table I. The zone-melted iron and Fe-Mn alloys were made by Battelle Memorial Institute. Iron S-1 was arc-melted in a water-cooled steel mold in an argon atmosphere. The ingot was forged into a bar, then given two horizontal zone-refining passes in an alumina boat. Iron V-4 was treated in a similar manner, but was not zone-refined. The iron for the zone-melted Fe-Mn alloys was induction melted in vacuum in MgO crucibles and cast into alumina molds. The ingots were forged into bars, machined to shape, and a groove milled down one side of each. The best available electrolytic Mn was placed in the grooves, and the bars were zone melted. The vacuum-melted Fe-Mn alloys were induction melted in this Laboratory in MgO crucibles and poured into cast-iron molds. Iron V-5 was purchased from National Research Corp. in the form of a small vacuum-cast ingot. The low-carbon steel was made by induction melting in air at the U.S. Steel Corp. Applied Research Laboratory. The history of the materials prior to the final cold reduction differed; these details are given in the Appendix. The penultimate grain size of the principal materials was kept in the range ASTM 2 to 4, except for the low-carbon steel. PROCEDURES The cold work prior to the final recrystallization anneal was kept constant at 60 pct. It is known that rolling procedure can influence the kinetics of recrystallization of ironI2; therefore, all specimens were rolled in one direction only, between clean,

Jan 1, 1962

By Armando M. Lago

Secular and cyclical patterns of postwar sources and uses of funds of the mineral sector are analyzed. A simultaneous equation behavior model of sources and uses of funds is developed for both mining firms and integrated producers, and these models were put through the task of predicting the financial and expenditure be-havior of mineral corporations in response to mergers and changes in investment tax credits and depletion allowances. Finally, the quantitative analysis methodology is applied to the analysis of optimum capital structure of mining corporations. The postwar changes that have occurred in the expenditure and financial behavior of mineral corporations are reviewed, particularly the relative importance of factors that affect the industry's supply and demand for funds. This quantitative statistical investigation of factors affecting sources and uses of funds of mineral corporations is achieved through the formulation of a simultaneous equation model of sources and uses of funds. After a description of the study sample, the postwar cyclical and secular financial behavior of mineral corporations is analyzed in detail. An econometric model of mineral corporate financial behavior is formulated. This model is then estimated and reviewed. Policy issues regarding depletion allowances, investment tax credits, and industrial organization of the mineral sector are discussed. Finally, the optimum financial structure of mining firms is discussed and the effect of corporate financial structure on the mining corporations' average cost of capital is analyzed.

Jan 1, 1971

By John S. Johnson, Thomas Fraser

SIZING is the process of separating mixed particles into groups of particles all of the same size, or into groups in which all particles L range between certain definite maximum and minimum sizes. In coal preparation, sizing is generally accomplished by passing the coal over screens. Separation by differential settling in air or water currents has been adapted to the special field of separating very fine sizes, and these processes are in commercial use to a relatively small extent in the coal industry. Separation with screens is a very old industrial practice. Agricola 1 described the use of screens for ore treatment in the middle ages. In the literature of the British coal industry references were made to the screening of coal as early as 1589, but the practice of extensive sizing for the market did not become general until the last half of the nineteenth century. In America, the practice of sizing developed first in the Pennsylvania anthracite region, beginning with the use of rakes2 in the mine working places to recover coarse coal. This mining procedure left the fines in the mine. Preparation outside the mine started with the installation of stationary cast-iron plates with 4 to 6-in. square holes. The run-of-mine coal was dumped upon the platforms, the large pieces of rock were picked out by hand, and the large lumps of coal were broken with hammers. The term "breaker," which still applies to the anthracite-preparation plant, originated with this practice, but the term is no longer descriptive of the entire function of the plant. In 1884, the first power-operated anthracite coal breaker3 was erected by Gideon Bart at his colliery at Wolf Creek near Minersville, Pa. This plant utilized a system of rolls for breaking the coal and revolving screens for sizing. The plant was driven by a steam engine. It could handle

Jan 1, 1943