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By AIME AIME

THE Institute of Metals held a well rounded out symposium on the working of metals, distributed over two sessions. At the first session* four papers were presented, two dealing with the, cold working of metals and alloys and two with the hot working of non-ferrous alloys. The first paper by E. V. Crane, dealt with "Metal Working in Power Presses." Mr. Crane pointed out the empirical nature of engineering data available for use in calculating the probable stresses developed and power requirements, for the shearing, drawing, binding and other forming operations. He described the various operations, methods of determining stresses developed and presented data obtained. In the discussion C. F. Hammond took exception to Mr. Crane's objections to the rather too frequent. annealing operations in drawing of cartridge cases, pointing out that the material was-manufactured to meet specified structure and physical requirements, which could only be met by carefully controlled sequences of working and intermediate annealing operations.

Jan 1, 1931

By M. E. Bell

The term "operational research" was probably first used to describe work started under E. C. Williams, now Director, SHAPE Air Defense Technical Center, late in 1937 or 1938, at the Bawdsey Research Station of the British Air Ministry, a laboratory center concerned with the development of radar equipment. After the practicability of the early techniques had been demonstrated, a large (for those days) program of development and installation was authorized. It was very soon realized, both by the Royal Air Force and by the scientists that almost as important as the gear itself was the way in which it should be used. Accordingly, it was decided that some scientists should cooperate to study the way in which the equipment should be deployed and operated in conjunction with the Royal Air Force. To distinguish this work from the normal work of a research and development establishment, the term "operational research" was coined. It merely meant at this time that this particular section of scientists was to be concerned with the use of the gear rather than with its technical development and it seemed natural to those concerned to adopt the word "operations" which has a specific connotation in the armed forces.' This method was later extended to peacetime business enterprise, government operations and other human activities. Operations research appears to have penetrated the extractive industries more slowly and less completely than other industries, the military, or the government. This may be due (1) to a difference in the attitude of management towards operations research, or towards research of any kind, for that matter; (2) to unsuitability of the extractive industries for application of the operations research method; (3) to inaccessibility of the data; (4) or to a lack of trained personnel who are interested in applying operations research to the mineral industries.

Jan 8, 1963

By Dean, R. S.

THE numerous theories of hardening which have been advanced in recent years are all satisfactory in accounting for some of the phenomena observed in hardening metals, but none so far presented account for all of the facts observed. Some years ago one of the authors, R. S. Dean,' presented a theory to account for some of the properties accompanying work hardening. The present paper develops this theory further in the light of recent experimental work and extends it to other forms of hardening. Many of the ideas included have come from the writings and personally communicated thoughts of others. We have attempted to give proper credit in every case, but it is possible that we have not always done so. As an historical basis it is desirable here to review very briefly the hardening theories which have been current. The first comprehensive theory of work-hardening phenomena was due to Sir George Beilby.2 He contributed the idea that with cold work part of the structure of the metal was rendered amorphous and that-it was to this amorphous material that the cold-worked metal owed its difference in properties. According to Beilby's theory this amorphous material was a supercooled liquid and, therefore, had the characteristics of a vitreous material. That such a theory is not capable of explaining the property changes in metals has been repeatedly pointed out. This theory also allowed a slip to take place only once on a given plane, which, as has been pointed out by Jeffries and Archer13 is not consistent with the observed length of an, individual slip and the amount of elongation which can be obtained by wire drawing. The modifications, which have been proposed to this hypothesis to make it coincide with the experimental facts, have to a considerable extent robbed the theory of its clean-cut characteristics. The commonest of these modifications replaces the amorphous phase with an

Jan 1, 1927

By Eifu Moriyama

In 1953, Akita Plant, having a capacity of 560 tons per month, was built at Akita city by Mitsubishi Metal Mining Co., Ltd. for the purpose of treatment of the Ikuno and Akenobe Mines's zinc concentrates. Akita city, in whose neighborhood the black ore has been discovered, is located about 500 Km north of Tokyo and faced with the Japan Sea. This plant has been continuously expanded to have the capacity of 7,500 tons per month by the end of 1969. Efforts have been made to mechanize installations and to achieve continuous process. One of the characteristics of Akita Plant is the recent establishment of the residue treatment process. Many processes had been investigated, and finally commercial sulphate roasting of the residue has been carried out since 1965. At Akita Plant, special high grade electrolytic zinc, zinc alloy for die-casting (MAK brand), cadmium, cement copper and sulphur dioxide gas are produced. Sulphur dioxide gas is sent to the next door fertilizer plant to make acid. Table 1 shows production and the average assay of the electrolytic zinc and cadmium in 1969. This plant is divided into four main sections, two subsections, and residue treatment sections: Main sections are: (M-1) roasting section, (M-2) leaching and purification section, (M-3) electrolysis section, (M-4) melting and casting section,

Jan 1, 1970

By Frederic P. Dewey

This old and well-known method of determining silver is, in bullion work, so far superior to the furnace-assay that it is looked upon with reverential awe by many, if not by most, users, and its ease of execution, with proper equipment, commends it highly where much commercial bullion work on silver is required. The method is so thoroughly well known that a description of it here may seem to be unnecessary, but many thousands of determinations are annually made by it in the U. S. Mint Service and its practice is there reduced to an art. This is necessary both for the sake of economy of time, and because high-grade work with it requires constant practice. It is useless for a person who uses it only occasionally to expect to attain high accuracy with it, without spending more time upon a detemination than is warranted in a busy commercial laboratory. It is always employed in the Mint service whenever possible, but its chief field is in the determination of silver in standard silver (ingots and coin), which is 900 fine in silver and 100 fine in copper, and I shall first briefly outline its use on this metal and then take up various points in detail, especially as related to the accuracy of the results obtained. For this determination 1,115 mg. of standard metal are weighed and transferred to a glass-stoppered bottle, the metal is dissolved in nitric acid, and 100 cc. of a standard solution of NaCl run in. The bottle is then vigorously shaken and a measured portion of a decimal salt solution added, and again shaken, if necessary. These operations are repeated until the silver is precipitated. Standard metal being 900 fine, 1,115 mg. should carry 1,003.5 mg. of silver, which is a convenient figure to work with.

Jan 1, 1914

The regular activities of the Institute are financed mainly by income derived from members' dues, from advertising in MINING AND METALLURGY, and from the sale of publications to the public. In addition, collateral activities and special projects are financed each year by means of income from endowed funds controlled and administered by the Institute. In the aggregate, the principal sums of these endowments amount to more than $530,000. An active effort is being made to increase the endowment funds of the Institute through a standing committee, of which H. T. Hamilton is chairman, and of which the other members are: W. H. Aldridge, George D. Barron, Cleveland E. Dodge, D. C. Jackling, Henry Krumb and J. V. W. Reynders. This committee feels that there exists a tremendous opportunity for the Institute to be of ever-growing service to the public, to the mineral industries, and to the profession. It welcomes suggestions as to names of men of means who are vitally interested in the mineral industries, and to whom the opportunity to make a contribution or bequest might appeal favorably if presented in the proper light by the committee.

Jan 1, 1941

By P. Nicholls

Though the burning of fuels extends far back into antiquity, and though fuel beds are the most common and widely distributed example of chemical actions and engineering practice, there has been little attempt to group fuel beds by types or to define the principles associated with them. This paper does not profess to cover completely the subject of fuel beds. It suggests some of the over-all principles of the two more common types. No new investigational data are included, but the deductions are largely based on a recent publication of the U.S. Bureau of Mines'. Definition of Types There are three primary types of fuel beds: (I) Underfeed, in which the fuel and the air move in the same direction; (2) overfeed, in which the fuel and the air move in opposite directions; (3) crossfeed, in which the fuel and the air move at right angles to each other. The principle that fixes the type is the relation between directions of the flow of fuel and of air. Fig. 1 shows the three types diagrammatically. All other types are compounded of these three in a simple or more or less complex manner. It does not follow that these three type designations are limited to the methods used in representing them in Fig. 1; they may be turned in any direction, and as long as the relative directions of the fuel and air are the same the type is not changed. For example, A as shown .resembles a pot-type stoker, but the air and fuel can move downward as in the so-called smokeless heating boiler furnace. Also, C can be placed horizontal, as in chain-grate stokers. For this reason, the terms used to designate the three types are not all that could be desired; more logical ones could be coined, but those used probably are satisfactory until the discussion of fuel-bed types becomes more common.

Jan 1, 1936

By P. Nicholls

Though the burning of fuels extends far back into antiquity, and though fuel beds are the most common and widely distributed example of chemical actions and engineering practice, there has been little attempt to group fuel beds by types or to define the principles associated with them. This paper does not profess to cover completely the subject of fuel beds. It suggests some of the over-all principles of the two more common types. No new investigational data are included, but the deductions are largely based on a recent publication of the U.S. Bureau of Mines'. Definition of Types There are three primary types of fuel beds: (I) Underfeed, in which the fuel and the air move in the same direction; (2) overfeed, in which the fuel and the air move in opposite directions; (3) crossfeed, in which the fuel and the air move at right angles to each other. The principle that fixes the type is the relation between directions of the flow of fuel and of air. Fig. 1 shows the three types diagrammatically. All other types are compounded of these three in a simple or more or less complex manner. It does not follow that these three type designations are limited to the methods used in representing them in Fig. 1; they may be turned in any direction, and as long as the relative directions of the fuel and air are the same the type is not changed. For example, A as shown .resembles a pot-type stoker, but the air and fuel can move downward as in the so-called smokeless heating boiler furnace. Also, C can be placed horizontal, as in chain-grate stokers. For this reason, the terms used to designate the three types are not all that could be desired; more logical ones could be coined, but those used probably are satisfactory until the discussion of fuel-bed types becomes more common.

Jan 1, 1936

By Tracy Jarrett

IN making gold alloys possessing certain physical properties, such important factors as corrosion resistance, color, hardness and melting points must be considered. All of these requirements depend directly upon the composition. It is possible to obtain the same colored gold alloy by using different compositions, but in doing so one may bring in some undesirable property. Other investigations have been carried on in this field by F. E. Carter,1 E. M. Wise,2 and L. Sterner-Rainer.3 To make a complete study of the effect of composition upon these properties, a systematic investigation was carried on involving a range of copper content from 85 to 65 per cent. Elements such as zinc, silver and nickel were used to replace in part the copper content. The gold content in all the alloys remained constant. Only 10-karat gold alloys of those containing 41.6 per cent gold will be considered. All of the alloys were made in an induction furnace. Each alloy was cast in a 3 by ¼ by ¾ -in. ingot. The method of obtaining the melting points and making color determinations was described in a previous paper.4 The Rockwell B scale with the ball and 100-kg. weight was used for all hardness determinations. The submersion of test pieces in concentrated nitric acid is one of the standard corrosion tests used in the optical trade. A test piece in the 50 per cent cold-worked condition, ½ by 2 by 0.043 in., is blanked from a strip using a. die, and the weight, loss per square inch of surface is taken as a means of comparison. The time for this test is 2 ½ hr. of actual sub-mersion of the test piece in the acid. This standard test was applied to all of the 10-karat gold alloys discussed in this paper. The tensile tests were made upon strips of the dimensions shown in Fig. 1. The test pieces after blanking were annealed at 1300° F. for 20 min. and cooled in air. The "drop of the beam" method was used in determining the yield point, as there was a very marked "drop" when the yield point was reached.

Jan 1, 1939

By Robert Anderson

ROUGHLY, a crack in a casting may be considered, for the moment, to be due to fracture of the alloy resulting from the stress set up by the contraction in volume on passing from the liquid to the solid state. Cracks may be external or surface, internal or deep-seated, or incipient or so-called strain cracks. Draws may appear as depressions, unevenness, and "pinching in" of the surface of a casting. Roughly, draws are due to contraction in volume and are governed largely by the same factors as cracks. A casting may be cracked, however, without being drawn. Shrinkage is a foundry term; it connotes the contraction in volume of a metal or alloy on passing from the liquid to the solid state. Pattern-makers' shrinkage is the total contraction in volume (including liquid, solidification, and solid shrinkage) that occurs when an alloy is poured into a mold. The contraction in volume of aluminum is one of the principal factors affecting the occurrence of cracks, as will be shown later, and the question of shrinkage and its control requires careful study in any treatment of cracking in castings. In the case of, sand and die castings, cracks have been attributed to a number of causes, but in the case of most light aluminum alloys, they are due to the large contraction in volume on freezing and the lack of its regulation or control. The most important factors are: (1) Contraction in volume; (2) composition of alloy; (3) quality of melting charge; (4) design of casting; (5) method of molding; (6) hardness of ramming; (7) method of gating; (8) hardness and characteristics of cores; (9) chills; (10) risers; (11) melting temperatures; (12) furnace used for melting; (13) pouring tempera-tures; (14) inclusions in alloys; (15) hot shortness of alloys; and (16) physical properties of alloys at high temperatures. Of these, the first, second, third, and eleventh to sixteenth involve ascertainable metallurgical facts; the remainder are largely matters of opinion, judgment and technical knowledge of men experienced in the production of castings.

Jan 10, 1921

Jan 1, 1971

By Kenneth R. Hancock

Iron oxides are unique in that they are the only significant colored mineral found in a natural state suitable for use as a pigment after it has been pulverized to pigmentary size. The current world production of iron oxide pig¬ments is estimated by the author to be between 450,000 and 550,000 tons based on 1969 data. The fact that highly colored natural deposits of iron ore are found throughout the world ac¬counts for its use in prehistoric man's artistic cave paintings. These early artists did not realize that they had established man's first paint test fence which now has some 20,000 years of exposure. In addition to abundance, constituting about 7 % of the earth's crust, iron oxides have the advantages of low cost, permanency, and are not toxic. Through the centuries, succeeding civilizations have utilized iron oxides as a major source for decoration and protection when coloring was desired. In the last century the chemical industry has improved on nature by developing a complete range of synthetic iron oxide pigments which surpass the pigments pro¬duced from natural iron ores in uniformity, color quality, and chemical purity. In the United States alone, the combined production of natural and synthetic iron oxides produced sales of over $28,000,000 in 1970 (Stipp, 1970). Nomenclature With the increasing importance of the syn¬thetic iron oxides it is necessary to make a distinction between the natural or mineral pig¬ments and the synthetic pigments. Natural pigments are those products which are derived from selected ores and should not be confused with iron ores mined for steel production. Iron ores that are mined for steel must be capable of being mined and reduced to iron on a com¬mercial basis. These ores are selected on the basis of iron content and processing economics. It is therefore unusual when iron ores for steel production are suitable for use as mineral pig¬ments. Natural pigment ore sources are se¬lected for their special physical-chemical prop¬erties and can command a premium price. Synthetic pigments, and in this instance iron oxides, are those pigments produced from basic chemicals. Through chemical synthesis pig¬mentary sized particles are produced as opposed to comminution, the major procedure common to all natural iron oxide pigments.

Jan 1, 1975

O. S. GARRETSON, Buffalo, N. Y.: If I may judge from the half-tone illustration engraved from a photograph of this medal and accompanying Dr. Prazer's paper, I do not think the cast ing is exceptionally fine. I have often made castings of simi lar character which I think were equally good. For instance, I have taken a coin, moulded it directly in fine sand, and cast from it in Scotch (or the equally good, if not better, Ameri can Scotch ") foundry-iron a copy quite as sharp and smooth as the original. The secret is in using very fine sifted sand. In fact, I have used for this purpose the dust which had accumulated on the beams overhead in my foundry, riddling it with a very fine sieve before using it. ['NOTE BY THE SECRETARY.—After the session at which these remarks were made by him, Mr. Garretson cast at his Buffalo foundry, in the presence of a number of members of the Institute, copies of the bronze pin furnished to visiting members by the Local Committee of the Buffalo meeting. The accom panying illustration, Fig. I, has been reproduced from a photograph of such a casting, made in green sand, under the conditions of ordinary foundry-practice, and not subsequently polished in any .way. I can also certify that the photo graphic negative was not touched, to improve its clearness of definition, before the production of the " half-tone" plate from which Fig. 1 has been printed. As, in the case of the Kytchtym medal, it was the thin, ribbon-like sprue, rather than the low-relief features of the medal itself, which indicated the fluidity of the metal and the sharpness of the casting, so in this work of Mr. Garretson it is the long and slender pin which offers the strongest evidence of these qualities. It is scarcely neccssary to point out that the filling in the mould of a long and nar row opening, such as this pin presents, is the severest test that could be imposed upon the casting, and that the sharpness of the point of the pin in the casting is striking evidence of the success with which this test has been met. The Pittsburgh Testing Laboratory .has made for the American Manufacturer measurements of this casting and an analysis of the sprue. The thickness of the main casting is from 0.049 to 0.068 inch. That of the tag bearing the stamped number is 0.024 inch. The analysis, which represents the iron ordinarily employed by Mr. Garretson for thin castings, is as follows :

Jan 1, 1899

By J. T. Norton, Joseph Gurland

IN spite of the extended use and high state of practical development of the cemented tungsten carbides, the structure of these alloys is still a matter of considerable controversy. The characteristic high rigidity and rupture strength of sintered compacts have been attributed to a continuous skeleton of tungsten carbide grains, formed during the sintering process. This view is based mainly on the work of Dawihl and Hinnuber,1 who reported that a sintered compact of 6 pct Co maintained its shape and some of its strength after the binder was leached out with boiling hydrochloric acid. After leaching, only 0.04 pct Co was reported to remain in the compact. They also showed that the assumed increasing discontinuity of such a skeleton, as the cobalt content is increased, could be made to account for the observed discontinuous increase of the coefficients of thermal expansion, the loss of rigidity, and the impaired cutting performance of alloys of more than 10 pct Co. Contradictory evidence was cited by Sanford and Trent,' who mentioned that a sintered compact was destroyed by reacting the binder with zinc and leaching out the resulting Zn-Co alloy. The skeleton theory also does not account for the observed change of strength of sintered compacts as a function of cobalt content. If the skeleton is responsible for the strength, the latter would be expected to decrease with increasing binder content. Actually, the strength increases and reaches a maximum around 20 pct Co. In addition, tungsten carbide is brittle and undoubtedly very notch sensitive. The highest value found in the literature for the transverse rupture strength of pure tungsten carbide prepared by sintering is 80,000 psi.3 herefore, such a skeleton does not easily account for a rupture-strength value of 300,000 psi and higher, commonly found in sint.ered tungsten carbide-cobalt compacts. In view of the conflicting data present in the literature, experiments were undertaken to determine whether the sintering of tungsten carbide-cobalt alloys leads to the formation of a carbide skeleton or whether the densification behavior and the properties of cemented compacts are consistent with a structure of isolated carbide grains in a matrix of binder metal. The specimens were prepared from powders of commercial grade. Tungsten carbide powder ranged in particle size from 0 to 5x10-4 cm. Mixtures of tungsten carbide and cobalt were ball milled in hexane for 48 hr in tungsten carbide lined mills. After milling, the specimens were pressed in a rectangular die (1x1/4x1/4 in.) at 16 tons per sq in. NO pressing lubricant was used. Sintering of the tungsten carbide-cobalt compacts was carried out in a vertical tube furnace equipped with a dilatometer (Fig. I), by means of which the change of length of the powder compacts could be followed from room temperature to 1500°C. An atmosphere of 20 pct H, 80 pct N was maintained inside the furnace. Decarburization of the samples was prevented by the presence of small rings of graphite inside the furnace tube. The temperature of the sample was measured by a platinum-platinum-rhodium thermocouple, which also was part of a temperature control system able to maintain a constant temperature within ±100C. Pure tungsten carbide compacts were prepared by sintering the carbide without binder or by evaporating the binder from sintered compacts in vacuum at 2000°C. Since complete densification of these samples was not desired, they were sintered only to 60 or 80 pct of the theoretical density of tungsten carbide. The specimens were prepared for metallographic examination by polishing with diamond powders and etching with a 10 pct solution of alkaline potassium ferricyanide. Cobalt etches light yellow and the carbide gray. The amount of porosity is exaggerated since it is difficult to avoid tearing out carbide particles, especially from incompletely sintered samples. Experimental Observations A number of specific experiments were carried out in order to study some particular aspect of the sintering problem. The details of these experiments, together with their results, are as follows: Electrolytic Leaching: The binder was removed by electrolytic leaching from sintered tungsten carbide-cobalt compacts for the purpose of determining the continuity of the carbide phase. The method used was based on the work of Cohen and coworkers4 on the electrolytic extraction of carbides from annealed steels. If the sample is made the anode, using a 10 pct hydrochloric acid solution as the electrolyte, the binder is dissolved, but the rate of solution of tungsten carbide is negligible. A current density of 0.2 amp per sq in. was applied. As shown in Fig.

Jan 1, 1953

By Charles Wurms, Robert Steinitz

DURING an investigation to determine the compatibility of several metals with tungsten, the degree of reaction between tungsten and lead was determined. A literature survey showed considerable disagreement between the results of various earlier investigators. Information presented by M. Hansen1 states that, according to S. Inouye,2 tungsten has very poor resistance against attack by molten lead, even at the low temperature near the melting point of lead. A phase diagram in the same reference indicates a solubility of 30 wt pct W in molten lead at 1300°C. Contrary evidence was shown by Parkman and shepard3 in their investigation of materials for use in heat transfer systems containing liquid lead alloys; they performed experiments at 980°C for times up to 50 hr without noticing any appreciable attack on the tungsten. Tungsten sheet was immersed in molten lead contained in Vycor tubes evacuated to at least 10-4 mm Hg. R. Bernard4 and R. I. Jaffee5 also indicate that no reaction occurs between molten lead and tungsten. However, no experimental data were included in these reports. In order to settle the question of the solubility of tungsten in molten lead, tungsten powder with an average Fisher subsieve particle size of 6µ was pressed in a double-acting die at 6 tsi to small compacts. They were then sintered in an atmosphere of hydrogen for 2 hr at 1700°C, resulting in a sintered density of 64 pct of theoretical with final dimensions of 0.260 in. in height and 0.245 in. in diameter. For all tests, the tungsten pellets were immersed in molten lead. Table I is a summary of the experimental procedures showing atmospheres, temperatures, and times. The first experiments were performed at 650°C; at this temperature, the liquid lead should wet the porous tungsten better than at its melting point, and penetrate into the pores. The lead was heated in a graphite crucible with a graphite cover. No protective atmosphere was used, as it was expected that the formation of CO would be sufficient to prevent oxidation. This, however, proved to be wrong, and all tungsten samples showed a slight oxide film after treatment. The tungsten samples were immersed in the molten lead for times of 5 min, 10 min, 1/2 hr, 1 hr, and 2 hr. After this time, the melt was poured into a form and the

Jan 1, 1962

By Louis Huntoon

HISTORY of the Porcupine area has been pub-lished in detail by the Ontario Bureau. of Mines in several issues of its annual reports. An. interesting volume could be written on: this topic; especially if personalities were introduced, such as the. transaction whereby the original title to the Hollinger group of claims was settled between Ben Hollinger and Alex Gillies by the toss of a coin. The early history of the McIntyre mine also had its thrilling events, such as its manager, R. J. Ennis, dodging the sheriff and deposit-ing red-hot gold bricks in the bank to meet his pay-roll. The occurrence of quartz veins containing low gold values was reported in 1896 by E. M. Burwash and again in 1899 by W. A. Parks. The first application for a mining claim appears to have been applied for on Dec. 30, 1906, by W. 0. Taylor, of Toronto, one of the old employees of the Hudson Bay Co. On the recom-mendation of Mr. Taylor, early prospecting was done on the shores of Porcupine Lake. It. was not until the spectacular discovery of the surface croppings at the Dome mine, by J. S. Wilson in 1909, that a rush to the district took place. Exploration was carried on during 1910 and 1911. The big boom was on in 1911, when claims sold on the evidence of mere rock croppings, owing to the prevailing heavy overburden. Rock croppings with specks of gold brought big prices. The country was heavily timbered and most difficult to prospect. My first trip was made during the summer of 1911, while the railroad was under construction from Porquis Junction to South Porcupine. I published my observations in the Canadian Mining Journal, Dec. 15, 1911, discussing in particular the character of the ore deposits and the future prospects of the camp. The first mills were erected in 1911, only to be destroyed by the disastrous fire in July of that year. They were rebuilt and the first important shipments are recorded in 1912. The history of the camp from the discovery of the Dome to the present consists of alternate chapters of great optimism and those of a more non-committal nature. For the engineer unfamiliar with the character of the deposits of this area, and the north country in general, it is at times most difficult to draw conclusions and submit definite recommendations. When valuable orebodies apex at depth, with no surface showings other than slightly mineralized veins of quartz or quartz containing a little visible gold; when at depth valuable veins and ore deposits, paralleling the one being explored, are developed by cross-cutting, such as Nos. 85-58 on the Hollinger, which have been its largest producers, the engineer assumes responsibilities rarely called for in other mining districts. This fluctuating aspect is exemplified in the three large producers, and may be duplicated with some of the old producers now being explored.

Jan 8, 1923

Seattle offered sunny, dry weather to about 2500 mining men who assembled September 10 to 14 for the 1961 American Mining Congress. The impact of snappy sessions on national mineral policy, state of the industry and foreign competition (to name only a few) was somewhat overshadowed by enthusiasm of conventioners for salmon fishing. This lordly fish, which mysteriously runs to its hatching place to spawn and die at this time of year, was not cooperating with the anglers in Puget Sound. However, this did not prevent consuming ample amounts of the deliciously prepared Quinault salmon at the "Potlatch" celebration.

Jan 10, 1961

By Herman Van Fleet, Frederick W. Neil, O&apos

The object of this paper is to describe the present status and possil~ilities of liquid oxygen as an explosive based upon the investigations, research and practical work of the Ingersoll-Rand Co., and of the Air Reduction Co., from early in 1922 to date. The following work was done. 1. A study of the history and physical theory of L. 0. X. as an explosive. (No attempt will be made in this paper to give the history or theory, as this has already been covered by the literature on the subject.) 2. An investigation of the use and the practice with L. 0. X. in the iron mines of Lorraine where L. 0. X. has its largest application in Europe. Although L. 0. X. is extensively employed in the iron mines of Lorraine, many of the mines using it exclusively, and blasting with it a total of approximately three million tons of iron ore per year, the fact that the mining practice in Lorraine1 is to drill comparatively shallow holes and blast only a few holes at a time, renders the data obtained there of very little value in estimating the possibility of replacing dynamite with L. 0. X. in American mining methods. In fact, in the iron mines in Lorraine, L. 0. X. replaced black powder, or its equivalent. 3. Laboratory research work on properties of absorbent materials. 4. Work in the Bureau of Mines explosive laboratory at Pittsburgh, Pa., on the properties of L. 0. 3. cartridges. 5. Practical work underground with L. 0. X. cartridges in the Kitherbee-Sherman iron mines at Mineville, N. Y. 6. Practical work in the quarries of the Calcite Quarry Co., Myers-town, Pa. 7. Practical blasting in several quarries and open-pit mines.

Jan 1, 1927

By W. A. Krivsky, R. Schuhmann

Jan 1, 1962

By R. G. Gifkins

Mean boundary migration depended linearly upon creep extension under various conditions. Prolonged annealing or air-casting increased the proportion of immobile boundaries at a given stage of tests. Grain growth during annealing followed a power law. The linking of migration and sliding in creep and models for migration are examined; activation energies are calculated from these models. Segregation of oxygen to boundaries appears to be a controlling factor. THE idea that boundary migration and boundary sliding during creep are linked has often been suggested,'-5 especially when evidence has been obtained for an alternation between the two processes. In simple bicrystals sliding can occur without any migration6 but in more complex bicrystals7 it is observed. McLean' and Couling and Roberts 5 made measurements of both sliding and migration; McLean concluded that there was no linking of the two processes whereas Couling and Roberts supported the idea. McLean' also developed a model for migration during creep and annealing. The present work was initiated as part of a study of the recrystallization of lead during creep9 but has been extended to examine some aspects of the mechanism of migration. MATERIALS AND METHODS Specially refined high-purity lead* was used; the total of impurities, excluding oxygen, was 0.0008 wt pct. Oxygen was removed as far as possible by melting in vacuo, treating at 550" to 600°C with hydrogen and then casting at 450°C under a vacuum of 10-2 mm Hg; the oxygen was then believed to be 0.00005 wt pct. Specimens were made from extruded strip and then annealed at the required temperature in an air oven, controlled to 5 lac. They were then polished in a mixture of acetic acid and hydrogen peroxide. At this stage some specimens were etched to give grain contrast and their grain sizes determined by the intercept method. Migration of boundaries during creep was measured on the surface of polished (not etched) specimens, directly loaded at room temperature (22°C) or 50°C (52"C) to initial stresses of 300 to 700 1b per sq in. Twenty six vacuum-cast hydrogen-reduced specimens were used and, in addition, two specimens were from material air cast after hydrogen reduction ("partial" air cast) and two from air-cast material not treated with hydrogen ("full" air cast). Duplicates were made in the majority of tests. At intervals through the creep tests, specimens were unloaded and the migration measured, normal to the direction of migration at the point of measurement, for each boundary along standard traverses. Usually between 110 to 180 boundaries were measured at each of some twelve stages of the tests. Migration was measured on the projected image (X100) using prism illumination. Fig. 1 illustrates the method of measurement and shows the kind of variation of migration found from boundary to boundary and along particular boundaries. Fig. 2 gives an example of more extensive migration. The mean value of distance migrated was generally reproducible to *10 pct but occasional points gave a scatter of *20 pct. The correctibn applied by McLean8 to allow for the contribution sliding makes to the apparent distance of migration could not be used, for the sliding at most boundaries was too small to measure with the equipment available. There were two reasons for supposing the correction unnecessary in the present work;

Jan 1, 1960