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By C. L. Clark, J. Russ

For many years attempts have been made to develop a laboratory test that would serve to indicate the proper temperatures to be used in the various hot-working applications to which metals may be subjected as they are being processed from the cast ingot to the desired finished products. That these attempts have not been very successful is indicated by the fact that most of the temperatures in use today in these operations have been developed over a period of years by trial and error. In other words, the selection of the proper temperatures for the hot-working of metals is generally an art rather than a science. Our knowledge with respect to the behavior of metals at elevated temperatures has been greatly extended during the past several years. While most of the work in this field has been done at proposed operating temperatures of equipment, rather than at processing or fabricating temperatures, one outstanding fact has been developed, which is applicable to the entire high-temperature range; that is, that the rate of deformation to which the metal is subjected is of the same order of importance as the temperature. The failure to properly recognize this fact has greatly retarded the development of a suitable laboratory test for determining hot-working temperatures. Influence of Rate of Deformation on High-temperature Properties It is not the intent of this paper to survey all the work that has been done On the effect of deformation rate On the properties of metals. The importance of this factor, however, was shown by Zay Jeffries' as early as 1919, when he called attention to the existence of the so-called equicohesive temperature and to the effect of certain factors on the location of this temperature' Fig. I is a diagrammatic sketch showing the effect of temperature On the relative strength of the crystals and grain boundaries and the type of fracture that will res depnding On the location of the test, or Or temperature with respect to the equicOhesive temperature. Since the type fracture varies, it also follows that at temperatures below the equicohesive temperature the major deformation occurs in the grains: while at temperatures above, the deformation results either from the movement of the grains with respect to each other or recrystallization of the strained material occurs almost instantaneously, producing new crystals at the fracture. As previously indicated, it is an established fact that the position of this equicohesive temperature for any given metal is dependent On the deformation rate' For example, in 0.15 per cent plain carbon steel the location of this temperature under

Jan 1, 1947

By Charles T. Van Winkle

Until the advent of the porphyry coppers and the introduction of flotation which soon followed, crushing and grinding for many years proceeded along somewhat stereotyped lines, without important alteration in type of machinery. For the finer crushing and grinding, stamps, rolls, and various patterns of Huntington and Chilean mills were in general use. Ball-mills were in use abroad, but owing to their small capacity and the high cost of screens and steel, they never obtained much footing in the United States. Tube-mills were first introduced into the crushing departments of cyanide plants when it was found that for crushing finer than 30-mesh other types of crushing machinery were not efficient. In order to crush with one pass, these mills were made 18 to 22 ft. (5.5 to 6.7 m.) in length. Pebbles were used as a grinding medium and the mills were lined with either silex blocks or fragments of quartz or flint pebbles set in cement. While the cylindrical tube pebble-mill had been used to some extent in small installations of concentration mills, the first instance of its use on a large scale was at the concentrating plant of the Miami Copper Co., where 8-ft. by 22-in. (2.5-m. by 55.9-cm.) Hardinge mills were tried out against Chileans. The results of these experiments led to the gradual replacement of the Chilean by the Hardinge mill. Robert Franke published an article' describing the work done, comparing the two types of mills. At the same time, according to Franke, a test was run using a 6-ft. (1.8-m.) Hardinge ball-mill as a substitute for rolls for intermediate crushing on 1/2-in. material. According to Franke, this mill was soon discarded, since it was found that to obtain the desired product the mill must be limited in capacity. The Miami Copper Co. made no test with other types of ball- or pebble-mills. Following this example, others installed the conical type; and when the Inspiration Consolidated Copper Co. decided to build a concentrator, it adopted the conical mill. As the requirements for mills would be very large, it purchased manufacturing rights in the State of Arizona from the

Jan 1, 1918

By Frank C. Canney

The word "other" in paragraph 4, line 11, column 1, page 205, should read "over;" the correct version of reason 2, this paragraph, is: 'L. . . 2) to evaluate the usefulness of certain geo-chemical techniques, V. C. Kennedy and S. W. Hobbs of the USGS had already studied the distribution of copper, lead, and zinc in the soils (both in background areas and over veins) and in the water and plants, providing a criterion for measuring the magnitude and effect of soil contamination; ...9 On page 206, in the top left hand corner of Fig. 1 (in the area bounded by 47°35' and 116°10), the reference to Fig. 3 is incorrect. The area of Pine Creek, South Fork Coeur d'Alene River, and portion of Big Creek (the area which includes, from left to right, Kingston, Pinehurst, Smelterville, and Kellogg) should be identified as that of Fig. 2A. The headings for columns 1, 3, and 4, Tables I and 11, page 209, column 2, were reversed when the paper was printed. The corrected tables are:

Jan 1, 1961

By Oliver Bowles

SUPERFLUOUS varieties and standards which are meriting the critical scrutiny of the manufactur-ing industry have a special significance in the non-metallic mining industries, where, many of the final or intermediate products are manufactured at the mine or quarry. Such processes of manufacture must be considered an integral part of mining in its broader sense. Improvements may be either elimination or standardization. - The chief requirement of elimi-nation is an agreement between consumers and pro-ducers based on facts deduced from: statistical data. Standardization is much, more complex. Standards .may be established only when a very; thorough knowledge has been gained of the physical and chemical properties of the products, and the requirements of consumers. The activities of the Bureau of Standards are. largely directed toward such determinations. Paving-brick manufacturers, together with highway engineers, representatives of certain engineering socie-ties, and Government bureaus, have agreed that of the 66 styles of paving brick on the market 11 only are, essential and 55 are superfluous. Steps have been taken to reduce the output of -all but the 11 standard types. It is customary for manufacturers of structural slate to prepare it in sizes specified by builders and architects. Thus the material cannot be manufactured in advance and the result is irregular activity of mills, delays in filling orders, etc. To improve this condition, the Structural Slate Co. has issued a series of pamphlets giving complete specifications of structural slate for various purposes. Architects find it so much easier .to, order slate from these sheets that standard sizes are specified in preparing plans for new structures. Slate switchboards are usually manufactured after. the order has been received. One manufacturer claims that 80 per cent. of all switchboards are of standard sizes, and he keeps such sizes in stock. The facility with which orders may be filled from stock, and the improved quality of seasoned switchboards, will undoubtedly influence electrical, companies toward a more uniform standardization in size. Simplicity, could be further attained by the elimination of minor irregularities in .style; for example, in the beveled. edges.

Jan 2, 1922

By James Terry Duee

No important producing developments took place in Colombia during the year 1928. This was at least partly due to the paralysis of operations by the passage, during the latter part of 1927, of a law which was regarded by the oil companies as confiscatory and unjust, and the promulgation of exceedingly stringent regulations of this law under decree No. 150, published Jan. 28, 1928. This decree, which contained 24 articles, practically prevented not only producing operations by the oil companies but even such activities as geological explorations and surveying, as severe fines were imposed for the possession of maps not registered with the Ministry of Industries. Both this regulatory decree and the law were subject to attack in the courts by several of the oil companies. The regulatory decree was suspended May 22 by Presidential proclamation, until the suits against it are decided by the Supreme Court and Council of State. Though another law was introduced into the Colombian Congress at a later date, no action was taken on it, and at the time of the writing of this paper, it would appear that no oil bill will pass the Colombian Congress during the present session. The Barco concession, which was revoked in February, 1926, still continues an unsettled matter, although there have been rumors that the government was attempting to come to some decision on this rather difficult question. A hopeful sign toward the close of the year was the settlement of negotiations with the Tropical Oil Co. over the acceptance of the payment for royalties due the government from that company. This settlement, which covered a royalty on crude oil produced from June 30, 1926 to June 30, 1928, represented a cash payment for approximately 3,000,000 barrels. It is to be hoped that during the coming year the Colombian government will see its way clear to clarify its position on petroleum legislation. A good augury for the future was the statement made by President Abadia Mendez on New Year's Day, in which he courageously admitted the errors of previous legislation and said, regarding oil, "Very soon

Jan 1, 1929

By Russell W. Mumford

LITHIA compounds have a place in pharmaceutical and other chemical industries and lithium minerals in glassmaking and ceramics. The metal, although rare, is used to a minor extent in alloys. During the nearly 50 years of production of lithium minerals in the United States, the silicate mineral spodumene has continued as the chief source of raw material for the manufacture of lithium salts. Although twice as much lepidolite, a lithium mica, has been mined, most of it has been used in the making of certain types of glass. Amblygonite has been an additional but minor source of lithium compounds. Triphylite, petalite, and zinnwaldite have also been utilized in the past. All of these commercial lithium minerals contain low percentages of lithium (Table 1). In 1938, a new raw material for manufacture of lithium compounds made its appearance. This product was crude dilithium sodium phosphate (Li2NaPO4), obtained as a by-product of manufacture of potash and soda chemicals from the brine of Searles Lake, California. Searles Lake, which is now dry, lies in the extreme northwest corner of San Bernardino County, California, and consists of a large mass of salts. It was estimated by the United States Geological Survey that the crystal body contained about 25 pct voids, which are filled with a saturated brine. The brine consists mainly of the sulphates, chlorides, carbonates, and borates of sodium and potassium. Several other acid radicals, including phosphates, are present. Lithium is present in the brine in an amount corresponding to 0.01 15 pct Li2O. In the course of evaporation of water from the brine, during the process of manufacture of sodium and potassium chemicals, dilithium sodium phosphate crystallizes out and is recovered by a flotation operation. The lithium concentrate is filtered and dried and is then ready for shipment. It analyzes from 19 to 21 pct Li2O and now constitutes the highest known grade of crude lithium material. It is and will continue to be a major source of lithium for manufacture of lithium products. The variation in lithia content of the commercial minerals as mined is due to replacement of the lithia by soda and potash, to partial alter-

Jan 1, 1949

By F. Banemann

In discussing the problem of abnormal magnetic polarization, C. A. Heilandl† emphasized the unfortunate fact that our knowledge of the geological and physical conditions relating to such occurrences is very limited and that a more detailed insight into their physical causes would be extremely valuable for interpreting measured anomalies. He also pointed out that to arrive at quantitative physical formulas that would express the conditions that cause abnormal polarization many more occurrences of the kind would have to be recorded. The first part of this paper is a contribution to such descriptions. Abnormal Magnetic Polarization in South Africa The occurrence was mapped in the course of a magnetometric survey carried out about 70 miles to the east of Johannesburg and east of the Witwatersrand gold field, for the purpose of detecting the position of the suboutcrop of certain magnetite-bearing shales that occur in the lower portion of the Witwatersrand system of sediments, shales whose position in section in relation to the ore-bearing members of the same system of sediments are known. In this case the shales are covered by younger strata several hundred feet thick. Lines of magnetometric traverse were run at right angles to the strike for a strongly magnetic body. This body is a shale zone in the Witwatersrand sediments and has a strike of N.20°E. (magnetic) and dips 15" to the east. The field work was done by a vertical intensity field balance (A. Schmidt principle). The plotting is done in such a way that the sign is reversed from that usually employed in the northern hemisphere, so that a positive profile is obtained in abnormal cases while the same conditions in the northern hemisphere would give a negative one. This method of recording should be kept in mind in reading what follows.

Jan 1, 1940

By F. Banemann

In discussing the problem of abnormal magnetic polarization, C. A. Heilandl† emphasized the unfortunate fact that our knowledge of the geological and physical conditions relating to such occurrences is very limited and that a more detailed insight into their physical causes would be extremely valuable for interpreting measured anomalies. He also pointed out that to arrive at quantitative physical formulas that would express the conditions that cause abnormal polarization many more occurrences of the kind would have to be recorded. The first part of this paper is a contribution to such descriptions. Abnormal Magnetic Polarization in South Africa The occurrence was mapped in the course of a magnetometric survey carried out about 70 miles to the east of Johannesburg and east of the Witwatersrand gold field, for the purpose of detecting the position of the suboutcrop of certain magnetite-bearing shales that occur in the lower portion of the Witwatersrand system of sediments, shales whose position in section in relation to the ore-bearing members of the same system of sediments are known. In this case the shales are covered by younger strata several hundred feet thick. Lines of magnetometric traverse were run at right angles to the strike for a strongly magnetic body. This body is a shale zone in the Witwatersrand sediments and has a strike of N.20°E. (magnetic) and dips 15" to the east. The field work was done by a vertical intensity field balance (A. Schmidt principle). The plotting is done in such a way that the sign is reversed from that usually employed in the northern hemisphere, so that a positive profile is obtained in abnormal cases while the same conditions in the northern hemisphere would give a negative one. This method of recording should be kept in mind in reading what follows.

Jan 1, 1940

By Herbert Clark Hoover, Lou Henry Hoover

GEORGIUS AGRICOLA was born at Glauchau, in Saxony, on March 24th, 1494, and therefore entered the world when it was still upon the threshold of the Renaissance ; Gutenberg's first book had been printed but forty years before ; the Humanists had but begun that stimulating criticism which awoke the Reformation; Erasmus, of Rotterdam, who was subsequently to become Agricola's friend and patron, was just completing his student days. The Reformation itself was yet to come, but it was not long delayed, for Luther was born the year before Agricola, and through him Agricola's homeland became the cradle of the great movement ; nor did Agricola escape being drawn into the conflict. Italy, already awake with the new classical revival, was still a . busy workshop of antiquarian research, translation, study, and publication, and through her the Greek and Latin Classics were only now available for wide distribution. Students from the rest of Europe, among them at a later, time Agricola himself, flocked to the Italian Universities, and on their return infected their native cities with the newly-awakened learning. At Agricola's birth Columbus had just returned from his great discovery, and it was only three years later that Vasco Da Gama rounded Cape Good. Hope. Thus these two foremost explorers had only initiated that greatest period of geographical expansion in the world's history. A' few dates will recall. how far this exploration extended; during Agricola's lifetime. Balboa first saw the Pacific in 1513 ; Cortes entered the City of Mexico in 1520; Magellan entered the Pacific in the same year ; Pizarro penetrated into Peru in 1528 ; De Soto landed in Florida in 1539, and Potosi was discovered in 1546. Omitting the sporadic settlement on the St. Lawrence by Cartier in 1541, the settlement of North America did not begin for a quarter of a century after Agricola's death. Thus the revival of learning, with its train of Humanism, the Reformation, its stimulation of exploration and the re-awakening of the arts and sciences, was still in its infancy with Agricola. We know practically nothing of Agricola's antecedents or his youth. His real name was Georg Bauer (" peasant "), and it was probably Latinized by his teachers, as was the custom of the time. His own brother, in receipts

Jan 1, 1950

By R. L. Mauger, P. E. Damon, B. J. Giletti

This report includes the lead isotopic dating of a suite of galenas from Arizona and an application of the K-Ar method to the dating of a Laramide porphyry copper deposit, the Silver Bell Mining District. The lead isotopic data supports prior age assignments based upon geologic inference. The Silver Bell study illustrates the necessity of correlative geologic and petrographic investigations for the interpretation of the results of potassium-argon dating. LEAD ISOTOPIC DATING OF GALENAS FROM ARIZONA ORE DEPOSITS A group of galenas from Arizona ore deposits have been analyzed for lead isotope ratios. The results were used to calculate model ages by the. method of Russell, Stanton and Farquhar,l6 in which the age is calculated directly from the Pb206/Pb207 ratio. The use of Pb206/Pb207 ratios eliminates the errors inherent in measuring the abundance of Pb204. The Holmes-Houtermanns model is the other model commonly used for calculating model ages. Both models assume that any lead sample is composed of primeval and radiogenic components and the calculated age is the time at which the lead was extracted from its source area. Using the Holmes-Houtermanns model, a lead is ordinary if its isotopic ratios lie on an isochron. The growth curve that passes through the experimental point determines the U/Pb ratio in the source area. The RSF model assumes the source area for conformable leads is the mantle, that this has a uniform U/Pb ratio, and thus all ordinary leads must lie on a single growth curve, having a mantle U/Pb ratio. The definition of an ordinary lead differs between the models, and differences in age arise mainly from the assumptions made to evaluate parameters in the model equations. These assumptions depend on the hypothesis chosen to explain ore genesis. In the RSF Model, the Pb206/Pb207 ratio is derived as a function of time. The equation contains three undetermined parameters which are evaluated by assuming three known points lie on the curve. These are the following: 1) Primeval lead from the Canyon Diablo and Henbury meteorites, 2) Modern conformable leads which lie on Patterson's zero isochron, 3) Lead from the Bathurst, New Brunswick base metal deposits. The Bathurst deposits are postulated to be examples of "conformable base metal deposits", as proposed by Stanton.l9 A conformable deposit has a particular genetic history and, as a result, the orebody conforms to stratigraphic layering in the host rock. The metals are brought to the surface in volcanic rocks which originated in the mantle. Weathering products of these rocks, including sulfur and metals, accumulate in areas undergoing sedimentation. The formation of sulfide ion in the sediments by the action of sulfate reducing bacteria causes fixation of iron as pyrite. If the pyrite becomes concentrated in favorable stratigraphic horizons, any base metal deposit eventually formed by replacement of pyrite will have a strata bound character. Compaction and expulsion of pore water from the sediments at depth result in upward mobility of solutions containing soluble base metal chlorides. The strata with high pyrite content act as chemical traps for the base metal ions and replacement occurs. An important result of this general evolutionary model is that, if complete separation of lead and parent isotopes occurred during accumulation of the sediments, any ore deposit formed solely of metals derived from those sedimentary rocks will contain "conformable" lead. This would be true even if the actual ore deposit were formed at a later date by some epigenetic process. In this case, mineralization would be controlled by local conditions, and need not conform to stratigraphic layering. Also, any ore deposit containing lead derived from a mantle or mantle-like source, even though not conformable in Stanton's sense, will fall on the curve for conformable ores and thus give a meaningful model age. Model ages for Arizona galena deposits are listed in Table 1. Fig. 1 is a location map. Jerome-Humbolt District: Galenas from the United Verde mine at Jerome and the Iron King mine at Humbolt give model ages of 1750 m.y. and 1640 m.y. respectively. Both deposits are massive sulfide bodies in a host rock of older Precambrian

Jan 1, 1965

By Kefton H. Teague

Olivine is a mineral containing a mixture of forsterite (Mg2SiO4) and fayalite (Fe2SiO4) in solid solution. The name olivine was first applied by Werner in 1790 (Hunter, 1941) because of the olive-green color of the mineral. Olivine is the principal component of the rock dunite, which itself is a member of the peridotite group of ultrabasic igneous rocks. European uses of the terms olivine and dunite are somewhat different than US usage. In commerce European usage defines dunite as containing 36 to 42% MgO, 36 to 39% SiO2, and loss on ignition of approximately 10%. The term olivine is used to designate a material containing approximately 85% forsterite, with a chemical composition of approximately 45 to 50% MgO, 40 to 43% Si02, 5 to 8% Fe2O3, and ignition loss of 1 to 2%. Uses The principal use of olivine is in various applications involving hot metal. Table I shows the best estimate available as to the amount of olivine consumed by various industries worldwide. In excess of 90% of world uses involve hot metal, with approximately 75% as a slag conditioner in the blast furnace production of pig iron. Approximately 15% of total olivine usage is as a special foundry sand in mold making for the brass, aluminum, magnesium, and manganese steel foundries (Schaller, 1957, 1958; Snyder, 1957; Anon., 1977). Olivine was first used as an industrial mineral in the early 1930s for a refractory material (Anon., 1970; Hunter, 1941). As a refractory raw material, olivine was first introduced in the United States as hand-cobbed, selected, shaped blocks of crude olivine. This use met with limited success. More recently, finely ground olivine blended with MgO and pressed into bricks, which are then fired, has found use in glass tank furnaces and open-hearth furnaces. Ramming or gunning mixes for basic furnace linings also utilize olivine. Olivine has been used in ladle linings with varied success. In Europe, substantial tonnages of olivine are utilized in refractory brick for night storage heaters (Anon., 1970). A limited amount of olivine has been used in the past as a fertilizer (magnesium source) and has been fused with rock phosphate to produce a magnesium phosphate as a plant food. The relatively high magnesia (MgO) content of olivine also attracted attention to it as a potential source of both magnesium compounds and as a source of metallic magnesium (Bengston, 1956; Hunter, 1941). The use of olivine as an additive in the blast furnace is relatively new, having been developed during the last decade. J.W. Currier (Private communication, 1978) describes the behavior of olivine in the blast furnace as follows: Olivine (Mg, Fe2, Si04) represents a unique lime-free source of magnesia and silica as a blast furnace charge component. Only recently has the magnesia-rich mineral been recognized as beneficial cleaner for blast furnace experiencing the problems associated with excessive alkali inputs and/or low coke stabilities. For some time it has been known that alkalis tend to recycle and accumulate in blast furnaces. In the high temperature region of volatilization the elemental alkalis formed attack the integrity of the graphite structure. This alkali attachment is enhanced when poor coke is used. Higher in the furnace stack volatile alkali cyanides condense and oxidize. This accumulation of alkalis tends to agglomerate the burden materials, producing scabs and scaffolds. These structures not only inhibit the downward movement of burden materials and the upward passage of wind, but also lead to erratic furnace performance

Jan 1, 1983

By B. W. Gandrud

WET-PROCESS coal-washing tables as we know them today have been in use in this country for approximately 25 years. The literature records only a few table installations worthy of note prior to adoption of the present-day differential-motion table. According to Phillips,' six Campbell bumping tables were being operated by the St. Bernard Coal Co., Earlington, Ky., in 11893. As late as 1923, according to Richardson, 2 72 such tables were in operation in the Rosedale washery of the Cambria Steel Co., at Johnstown, Pa. Bumping tables probably were not used to any considerable extent except in the plant at Earlington, and at two or three plants in Pennsylvania, but they may be considered as forerunners of the present-day coal-washing table. The transition from bumping tables to the type of tables now in use signalized a revolutionary change in table design. The advantages of the new design over the old were so outstanding as to make its adoption inevitable. BUMPING TABLES Bumping tables, as the name implies, utilized a bumping action for conveying the refuse and discharging it over the refuse end. The tables were hung from rods attached to overhead supporting beams. A shaft and cam arrangement at one end of the table served as the actuating mechanism and imparted to the table an endwise, back-and-forth, swinging motion. A bumping block was fixed in the proper position at the shaft end, so that the table would strike against it at the end of each backward swing. The hanger rods or stirrups were so adjusted as to give the table a slight uphill slope toward the refuse end; that is, the end next to the driving mechanism. The feed box was near the upper end, of the table and designed to spread the mixture of coal and water over the width of the table. Wash water was added a short distance below the feed box with the table in motion and coal mixed with water being fed to it through the feed box, a certain amount of stratification took place, depositing heavy refuse at the bottom of the bed in contact with the surface of the table. Constant bumping and a certain amount of

Jan 1, 1943

By Morris Cohen

It has been known for several years that in certain age-hardenable alloys precipitation of finely divided particles occurs simultaneously with the changes in physical properties; while, in other alloys, these changes take place prior to, or without any, precipitation. The silver-copper alloys are generally considered to be the classical example of the first group, and the aluminum-copper alloys (duralumin) are typical of the second group. The two types of aging are explained by the precipilation theory and the knot theory respectively.‡ It is well recognized now that these theories do not conflict with each other; the one used for a given aging system depends upon which way the alloy in question happens to age-harden. However, previous work on the aluminum-copper al1oys1,2 has shown that if the aging temperature is raised sufficiently the hardening will be accompanied by actual precipitation. In fact, it is quite probable that all of the so-called knot-hardening alloys will harden by precipitation at elevated temperatures. Therefore, a combination of the knot and precipitation theories is necessary to give a complete picture of the agehardening of these alloys, and indicates that knot formation and precipitation are not independent processes. To test the generality of this concept, it is necessary to show that the alloys that commonly harden by precipitation will harden prior to precipitation if the aging temperature is sufficiently lowered. For this reason, it would be well to carefully re-examine the aging characteristics of the silver-copper alloys at aging temperatures somewhat below those used by previous investigators. If hardening can be detected prior to precipitation in these alloys, it will lend great weight to the idea that knot forma-

Jan 1, 1937

By Howard N. Eavenson

The information contained in the following paper was collected at the request of the U. S. Coal Commission, and is published with the permission of that body and of the various companies furnishing the data. For obvious reasons, the names of the companies are not given. No data were obtained from states south of Virginia or west of the Mississippi River. The data about the amount of labor, in man-hours, required in producing a ton of bituminous coal have been collected with the idea of showing what is being done at some well-managed plants, and not to show the average amount required by all mines, which undoubtedly is considerably higher than the average of the figures shown.* Almost all of the figures were supplied by the various companies in reply to a questionnaire; when they were obtained from other sources the company was asked to verify them. On account of the amount of work required, the data were only requested for one or two months for each plant, and the figures represent in each case a month when the car supply was good and the work was practically steady. In the case of most of the West Virginia and Kentucky mines, these conditions were best met in May and June, 1922. The mines for which the figures are given are arranged by states and as to whether the mine operates under union or non-union or open-shop conditions. The union mines listed are generally considered to be as well-managed as are the non-union ones. The production per month in a few cases includes the amount of slate which is loaded and hauled out of the mine, as of course this requires nearly as much labor per ton as does the coal. These cases are noted. The number of days worked includes only the total time in which the tipple operated; not the number of days on which the mines operated. This makes the output per day appear slightly higher than it should be in

Jan 1, 1924

SINCE I have told you of the distillation of waters and the extraction of oils from things-all ingenious and useful processes-I wish to continue to speak of the arts. I am reminded that I first wish to write down for you the discourse that I made to you on another occasion a few days ago concerning the operation of a mint, so that if you have lost it from your memory (and this would not be surprising since you have had no practice in it) you may repossess it if you should need to practice it or even to talk about it, and if you find yourself in this activity it may not be new to you. I told you, as I believe you will remember and so again I repeat, that a very great and constant diligence is required by one who wishes to operate a mint well, or to have it operated, because it has many parts which it is necessary for anyone who enters this work to understand very well; indeed, if he wishes that all the work of his helpers be done well, he will have to do it himself. And if it were possible, he should have a hundred hands and a hundred eyes together, and at the same time should be in different places, because some loss often occurs in what is handled because of the carelessness of the workers or because of their little real trustworthiness. It is understood that such things require great hard labors and many kinds of knowledge. The material handled in this work is most often either gold or silver all ready to be spent, and these things are very attractive to those who handle them. In addition to being made into pieces of money likely to disappear, it is very easy to lose, and whatever part is lacking for any reason whatever [132v] brings detriment and loss to the patron since it is a thing of value. Therefore, in short, anyone who wishes to exercise this art well, without being fraudulent therein, must watch the weights with all care because the essence of this art is naught but the division of a quantity of weight into many exactly defined pieces and the alloying of gold by carats and of silver by leghe, exactly established in accordance with what the prince grants you as remedy.* If through negligence you exceed in perfection

Jan 1, 1942

By L. R. Jackson

THE idea presented in this paper is that the capacity of a metal for plastic flow before rupture is dependent on the type of stress system applied-that is, the absolute magnitude of the stresses are unimportant provided that they are large enough to produce continued flow; the important factor is the "type" of stress system. A term called the "triaxial stress ratio" is defined in such a way that this ratio can be used to characterize the "type" of system. The paper is divided into three sections. The first section discusses means of representing the effect of complex stresses on plastic flow and defines "triaxial stress ratio"; the second section discusses various methods of' obtaining complex stress distribution. The third section gives some experimental results showing the effect of types of complex stress on the capacity of various metals for flow. An appendix discusses some details on methods of obtaining complex stresses. I. REPRESENTATION OF COMPLEX STRESS SYSTEMS AND THEIR EFFECT ON PLASTIC FLOW Representation of Stresses It is convenient to have a consistent system of notation that will allow the representation of the entire range of complex stresses from hydrostatic compression to hydrostatic tension on plastic flow in a single diagram. Such a system is provided by making use of the fact that any complex stress system can be resolved into a hydrostatic tension or compression and a pure shear. Consider a stress system having the principal stresses [S1 S2 5 S3]. This system can be resolved into a new system consisting of the three components [ ] and three pure shears. If Sm is positive, the net stress effect is hydrostatic tension; if it is negative, the effect is hydrostatic compression. In order to produce a systematic notation, a quantity that will be referred to as the "triaxial ratio" will be defined by the equation [ ] Sm is given by Eq. I and S1 is the absolute magnitude of the largest principal stress without regard to sign. Table I lists the triaxial ratios for various common systems. [ ] Representation of Strains Strains will be plotted as "true" strains according to the system proposed by Ludwik.1

Jan 1, 1944

By Denis G. Maxwell

INTRODUCTION It is my intention in this paper to deal with gold, uranium, diamonds, platinum, manganese, chrome, vanadium and heavy mineral sands. These are the most important strategic minerals produced by the Republic of South Africa which are not covered in other sessions of this program. In each case I have high- lighted the statistics and peculiar advantages which combine to make South Africa a vital source of these minerals. Before proceeding to give individual attention to these minerals I believe it would be useful to define what I mean by 'strategic'. The Concise Oxford Dictionary defines strategic in the context of materials as 'essential for war'. However it is commonly used in a much broader sense than this (often, in fact, very loosely) and I prefer to define it as 'concerned with the acquisition and maintenance of power, whether economic, political or military.' A VITAL SOURCE In dealing with the individual minerals I have quoted statistics which are contained in Tables 1, 2 and 3. Table 1 clearly shows the absolute size of the South African mineral industry. However, it can also be used to demonstrate the importance of the industry to the South African economy if compared with the GNP in 1980 of about R60 billion. Table 4 illustrates clearly how important South Africa is as a supplier of these minerals to most of the important industrialized countries of the Western World. Gold If anyone had any doubts about the inclusion of gold in a list of strategic minerals I am sure that the above definition of 'strategic' will convince them that it certainly belongs there. Similarly no one is likely to have any doubt about the fact that South Africa is a vital source of supply. Tables 2 and 3 show that in 1980 we had 51% of the world's reserves and accounted for 55% of world production. The figures for the Western World are considerably higher. The only other major producer, of course, is Russia, with small but significant production in the Pacific Rim area coming from Australia, Canada, Latin America, Papua New Guinea, Philippines and the U.S. All South African mine gold production is shipped in bullion form containing about 88% gold and 9% silver to the Rand Refinery which is a modern refinery with large scale units capable of refining half a ton of bullion at a time. The Refinery is equipped to produce standard 'good delivery' gold as well as 9999 gold and 999 silver. The Refinery also produces the 22 karat blanks which are, used by the South African Mint to produce Kruger Rands. It goes without saying that the South African gold mining industry leads the world in all aspects of deep-level, narrow-reef mining technology. The industry's metallurgists, too, have a record of tenacious and continuing efforts to improve extraction to the level of the present finely honed efficient process used on all the modern mines. Uranium In 1980 South Africa had 14% of the uranium reserves of the Western World and accounted for 14% of production. In view of the paucity of data I am not in a position to estimate figures for the total world. All the other major sources of uranium in the Western World are situated around the Pacific Rim, with the U.S. and Canada already being major suppliers and accounting for 38% and 17% of Western World production in 1980. Australian production at the time was small but they have very large reserves and production is already rising rapidly. The U.S., Canada and Australia account respectively for 22%, 19% and 29% of the uranium reserves of the Western World. South Africa has been a major producer continuously for 30 years. Nearly all the uranium produced, amounting to about 115 000 tons up to the end of 1981, was a by-product or co-product of gold extraction. During that time the industry has frequently led the world in technological innovation, and has established a reputation as a reliable producer of a consistent, high-grade product. In the latter respect, it is helped by the fact that production is marketed by one company, Nuclear Fuels Corporation, which also blends, dries and calcines the product from the individual mines and samples and assays it before shipping. Diamonds Diamonds are the rock on which the South African mineral industry is founded. The discovery of diamonds in 1866 gave rise to the first major mineral industry in the country and the profits from diamond mining helped to finance the gold mining industry 20 years later. Although now overshadowed by gold, diamonds are still very important in the overall picture of mineral production and exports, as can be seen in Table 1. There are really three separate diamond markets - gem, natural industrial, and synthetic - and, to be meaningful, statistics should be provided separately. Unfortunately separate figures are not available. The figures in Tables 2 and 3 show that, for gem and natural industrial together, South Africa ranks third in the world in production and second in reserves. South Africa is a major producer of synthetics and probably ranks second in the world after the U.S. Recently, of course, Australia was the scene of a major diamond discovery and will soon become the only

Jan 1, 1982

By Alfred G. Heggem

It is the purpose of this article to describe methods recently introduced into the oil and natural gas industry to safeguard the lives of the workmen and to protect property from destruction. Only such drilling methods are described as pertain directly to the operations necessary to maintain the well under complete control at all times. Wells Formerly Drilled Without Controlling Equipment It may seem incredible that practically all wells, until rkcently, were drilled without the provision of any means for control. To drill a hole into a boiler carrying high-pressure steam without first providing means to control the escape of steam would be unthinkable, yet in oil fields wells are drilled into a gas or oil formation with a possible pressure of 300 to 1,800 lb. per square inch and a daily flow of 20,000,000 to 80,000,000 cu. ft. of gas or 1,000 to 15,000 bbl. of oil per day. Some wells have produced in excess of 100,000 bbl. of oil per day, but these are exceptional cases. In addition to the loss of product, one must consider the great danger attendant upon the promiscuous liberation of such an amount of explosive and inflammable substance. Introduction of Metal Casing for Deep Drilling The introduction of metal casing to secure a permanent and impervious wall in a well made the drilling of deep wells possible and removed many of the original problems encountered in well drilling, but it did not insure the control of the well. To obtain the full value of the casing it was essential that a pressure-tight joint be made between the wall of the well and the lower end of the casing. Many materials in various forms were used, including cotton, hemp, stable refuse, oats, rice, cloth, leather, cork, rubber, lead, clay and cement, resulting, after a slow process of evolution, in the general adoption of two types of bottom fittings for

Jan 1, 1916

By M. V. Nevitt

In the systems Ti-Mn-O, Ti-Fe-O, Ti-Co-O, and Ti-Ni-O the bounda.r-ies of the Ti2Ni-type phases were determined at one or more temperatures and the variation of the lattice parameter with oxygen content was determined. Densities were calculated from the lattice parameters and compared with measured density values. The: results indicate that the occurrence of the phase in these systesms can be correlated qualitatively with valency electron concentration, and that the role of oxygen is that of an electron acceptor. The lower limit of oxygen solubility appears to be determined by the valencies of Mn, Fe, Co, and Ni, while the maximum oxygen concentration coincides with the filling of the 16 (c) positions of the O 7h - Fd 3m space group. THE suggestion has been made by several investigators'" that the phases having the cubic E9,-type structure, and known as 17-carbide-type, double-carbide-type and Ti,Ni-type, are members of a family of electron compounds. This concept has been given additional support by recent work8 in which new isostructural phases involving second and third long period combinations were found, and which provided further evidence of the regularity of occurrence of the phase in terms of periodic table relationships. In this laboratory attention has been focused on the isomorphs containing titanium, zirconium, or hafnium, and the role that oxygen plays in their occurrence. In some binary systems Ti,Nitype* phases occur having the formula A,B where A is the titanium group element. Based on previous workq and the present investigation, oxygen is known to be soluble in two of these binary phases, Ti,Co and Ti2Ni. It is probable that oxygen is also soluble in the other phases of this kind. In other binary systems the Ti,Ni-type phase does not occur, but does occur in the corresponding ternary systems with oxygen .3-5 The experiments described here were performed to determine whether the occurrence and composition of certain of the Ti,Ni-type phases could be related to an electronic effect and whether oxygen's stabilizing role is exerted through an influence on the electron: atom ratio. The ternary systems Ti-Mn-O, Ti-Fe-O, n-Co-O, and Ti-Ni-O were selected for study for two reasons: First, several schemes have been proposed for first long period elements which, although not in quantitative agreement, show a generally consistent trend for the variation of valency with atomic number. Although for a transition metal the term valency is difficult to define and is generally not a constant number which can be applied to all alloys, it is usually assumed to be an index of the number of electrons per atom involved in metallic cohesion. Second, the determination of the Ti2Ni-type phase boundaries was facilitated by the fact that the phase relations in several of these ternary systems have been investigated by other workers."' EXPERIMENTAL PROCEDURE___________________ The alloys were prepared by arc melting crystal-bar titanium, reagent grade TiO, and electrolytic manganese, iron, cobalt, and nickel. Each button was remelted at least three times. The metals had a minimum purity of 99.9 pct except the nickel whose purity was 99.4 pct, the major impurity in this instance being cobalt. The preparation of the manganese alloys was attended by the customary difficulties associated with the vaporization of manganese. The technique used in this case was to add approximately 10 pct extra manganese to the original charge and to continue remelting the button until the final weight was in agreement with its intended weight. At least three alloys in each system were analyzed chemically and the results, even for the manganese alloys, were in good agreement with the intended compositions. A few additional alloys in the Ti-Mn-O system were prepared by the sintering of mixed powders in evacuated quartz tubes followed in some cases by arc melting. For annealing, the alloys were wrapped in molybdenum foil and placed in fused silica tubes containing zirconium chips. The fused silica tubes were evacuated at room temperature to a pressure of 1 x l0-6 mm of Hg and sealed. These capsules were then annealed for 72 hr at an external pressure of 5 x 10-5 mm of Hg in a vacuum furnace whose temperature could be controlled to + 1°C. The success of this procedure in avoiding significant oxygen or nitrogen pickup was indicated by the bright, ductile condition of the molybdenum foil and by the complete absence of a microscopic reaction layer on the specimens. This method did not permit rapid quenching of the specimens but in no case did metal-lographic examination indicate that a solid-state transformation had occurred on cooling. Metallo-

Jan 1, 1961

By N. A. D. Parlee, N. M. El Tayeb

Fe-V alloys with small percentages of vanadium show no deviations from Sieverts' Law up to P~, = 1 atm in the 1600º to 1750ºC region. At somewhat under 8 pct V and up to at least 20pct V, at 1604" and 1661 °C, nitrogen absorption follows Sieverts' Law at low Pn2 values, but deviates from this law beyond critical values of pn2, due to formation of a nitrzde phase of approximately VN composition. The behavior below these solubility limits can be described at all temperatures by the equations: RAO and parlee1 suggested that the nitrogen absorption curve for liquid iron alloys takes the general form shown in Fig. 1 when an alloy nitride precipitate is formed. They showed that the precipitation of 6 titanium nitride from liquid Fe-Ti alloys follows this general scheme and dealt with the general theory involved. Recently, Evans and Pehlke2 reported their research on the precipitation of aluminum nitride from liquid Fe-A1 alloys. Fountain and Chipman's recent paper3 on the precipitation of boron nitride from solid solution contains a fine example of the analogous behavior which they have been studying in the solid state. Researches on the absorption of nitrogen by liquid Fe-V alloys have been described by various authors.1,4-7 Most of this work has been confined to fairly low vanadium concentrations and rather high temperatures because of difficulties variously described as, formation of surface scums, bridging, and so forth. This behavior and the rough thermo- dynamic calculations made by chipman,8 over eleven years ago, indicated that excessively high vanadium concentrations should not be required for vanadium nitride precipitation. It seemed desirable to look for and study this precipitation in order to fill out the thermodynamically interesting nitrogen absorption data on these alloys. EXPERIMENTAL METHOD The general method used was essentially the same as employed by Rao and parlee,1 in which a Sieverts type of apparatus was used and the precipitation of the nitride detected by the "break-point" in the Sieverts' Law line, and by the visual observation of the formation of the new phase on the surface of the melt. There were, however, a few differences in apparatus and technique as described below. The oil manometer used by Rao and parlee' to measure low partial pressures of nitrogen was not employed. The present authors sought to avoid as much as possible the exposure of the liquid alloy to low total pressures of gas during the 6 to 10 hr long runs because of the heavy iron evaporation-loss errors involved. This was achieved, partly by keeping evacuation times to a minimum with fast pumping but largely by the use of two burettes, one for argon and one for nitrogen, and using them to equilibrate the alloy with mixtures of argon and nitrogen rather than nitrogen alone. Each run involved a careful sequence of operations. After melting, de-

Jan 1, 1963