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By D. S. Kingery, D. W. Mitchell

The authors attended the 11th International Conference of Directors of Safety in Mines Research held in France, July 1963. In addition to Conference discussions pertaining to control of coal dust they had the added assignment to study present European practices for neutralizing the coal-dust explosion hazard. Information was obtained through discussions with the Research Directors, by visits to testing stations and observations of operating mines in various countries. This paper tells what the current practice in this field is in Europe, and how effectively coal dust explosions are controlled. The method is rock dust barriers. CONTROL OF COAL DUST DISSEMINATION Experience in Europe indicates that the control of dust production and dissemination by water or foam systems is not successful except during undercutting. Cybulski, Dawes, and DeBraaf - respectively Director, Mines Research Establishment "Barbara", Katowice, Poland; Principal Scientific Officer, Safety in Mines Research Establishment, Sheffield, England; and Chief, Central Mines Research Establishment, Hoensbroek, Treebeek, The Netherlands - believe that wetted dust becomes readily dispersible and abatement measures should be considered only as a temporary means for reducing the health hazard. In an effort to reduce the health hazard, calcium chloride is used on the floor of main haulageways in Dutch mines and water infusion is practiced in Germany in mines where the coal is relatively porous. With respect to wet coal dust, the Belgians, British, Dutch, French, and Russians reportedly have accepted the results of research from the Polish and American experimental mines on the effectiveness of water as an inert in arresting explosion propagation. The Polish use the two test methods proposed by the U.S. Bureau of Mines1 for evaluation of the adequacy of wetness of mine dust; they require that water be added to the wet dust to maintain a minimum of 50% moisture by weight if dependence is placed on water alone. GENERALIZED ROCK DUSTING The general attitude with regard to protection against coal dust explosions throughout Europe is that generalized rock dusting is a vital primary step to inhibit initial ignitions but definite emphasis is also placed upon the efficiency of rock dust barriers. Those exceptions to generalized rock dusting are Germany and Austria where some rock dusting is done but principal reliance is placed upon rock dust barriers. The rock dust used in Belgium, Holland, Russia, and Poland is coarser than that used in the U. S.; 50% of the dust is through a No. 200 sieve (75 microns). Recent research by the Polish indicates that the portion finer than 20 microns is ineffective in arresting explosion propagation, and that the rock

Jan 1, 1964

By J. H. Mallery, J. H. Keeler

THE crystal structure of Zral, the compound richest in zirconium (91.03 pct Zr by weight) in the system Zr-Al, has been found to be ordered face-centered-cubic. This compound is of particular interest, since it is encountered as the precipitated phase in potentially useful zirconium-rich alloys. It forms peritectoidally from body-centered-cubic zirconium and Zr,Al at about 975°C. The Zr-A1 constitution diagram has been reported by McPherson and Hansen.' For the primary determination a 100 g ingot was prepared by arc-melting in a water-cooled copper crucible under purified argon. The raw materials were crystal-bar zirconium (a purity of better than 99.7 pct) and spectroscopically pure aluminum. The ingot was double melted, examined metallographi-cally, and found to be quite uniform as shown in Fig. 1. The hardness of the as-cast button was VHN 390 to 445. A 20 mil diam specimen was prepared from annealed (900°C) filings of Zr,Al. The specimen was mounted in a 5 cm radius powder camera and an 8 hr exposure was taken using copper radiation with a nickel filter. The structure of the compound Zral was found to be ordered face-centered-cubic of the Cuau type, with an a,, value of 4.37220.003A. Its calculated density is 5.976e0.013 g per cu cm. The relative intensities for the lines were calculated using the formula 1+cos2 20 I oc----------------- • p • /F7 sin2 0 cos 0 1 + COS' 20 where----------------is the Lorentz polarization fac- sin2 0 cos 0 tor, p is the multiplicity factor, and F is the structure factor. The X-ray data are given in Table I. The compound has exhibited plasticity when present as particles in a matrix of a zirconium. During hot working at about 900°C, the compound has been found to deform plastically to the extent that some of the particles exhibit a length-to-width ratio greater than 4:1 as shown in Fig. 2. In answer to the discussion of ref. 1, McPherson and Hansen pointed out that the compound may be cold rolled and reduced as much as 33 pct. Zr,Al has also been found2 under certain conditions to precipitate in lamellar form at grain boundaries of the a phase of hexagonal-close-packed zirconium. Acknowledgment This work was carried out under Contract W-31-109-Eng 52 for the United States Atomic Energy Commission.

Jan 1, 1956

By Geo. H. Ashley

The following paper is intended to be suggestive only, and to open the way for discussion and further observation. Its preparation was requested only two days before the time limit set for the submission of the papers comprising this symposium. Thus no time existed for detailed studies, so it is largely a memorandum of such facts as have come incidentally to the notice of the writer in the study of coal in the field. The field study of sulfur in coal has received very little special attention or description from coal student's. The presence of sulfur concretions is noted in hundreds of descriptions, and certain benches of a coal bed may be described as "sulfury" or the presence and position of sulfur bands may be noted in coal sections in connection with sampling. It may be accepted that some sulfur is present in all coal. The amount varies greatly in different regions, in different beds, and in the same bed in different areas. The anthracite of Rhode Island comes the nearest of any coal known to the writer of being free from sulfur, several analyses of that coal showing less than 0.1 per cent. Subbitumi-nous coals in Colorado in a few places have close to 0.2 per cent. of sulfur on the dry-coal basis and in other states subbituminous coals approach this lower limit. Bituminous coals seldom run under 0.4 per cent. of sulfur on the dry basis, though in a few places dry bituminous coals in Colorado and Washington have between 0.3 and 0.4 per cent. The better known bituminous coals have almost everywhere over 0.4 per cent. The best of the Pocahontas and New River coals run close to 0.4 per cent., but there is very little commercial coal in Pennsylvania, Ohio, Indiana, Illinois, Kentucky, or the other states, that runs under 0.5 per cent. on the dry basis. From these minimum figures, the amount will range up to 5 or 6 per cent. or higher if visible sulfur is not excluded. It must be remembered that the usual analysis of a coal bed is not intended to give the total proportion of sulfur in the bed but the amount in the coal after the removal of the more obvious and larger sulfur masses. Professor Parr has already pointed out that, chemically, sulfur occurs in several forms: as pyrite, organic sulfur, sulfates, and possibly as un-combined sulfur. Sulfur in the form of sulfates is commonly the obvious result of the weathering of pyrite and may be found in the coal within .

Jan 1, 1920

By Carl F. Floe, Hung Liang, Michael B. Bever

DATA on the solubility of hydrogen in iron-silicon alloys are of practical interest, as hydrogen causes gas unsoundness and embrittlement in iron and steel and is also a factor in the metallurgy of cast iron. Zapffe and Sims1 have recently demonstrated that in deoxidized iron and steel castings gassiness and bleeding are primarily functions of the hydrogen content of the liquid metal. These authors also suggested convincingly that ordinary melting and casting practice provides several sources of hydrogen for absorption by the metal. Norbury and Morgan,2 and Boyles3 have shown that dissolved hydrogen affects the graphitization of cast iron. Schneble and Chipman4 included in a study of the effects of superheating on the properties of cast iron an investigation of the part played by hydrogen. Schwartz, Guiler and Barnett6 investigated the significance of hydrogen in the metallurgy of malleable cast iron. A complete interpretation of investigations of this kind calls for equilibrium values of the solubility of hydrogen in the liquid and solid phases. From the theoretical standpoint, the solubility of gases, especially hydrogen, may reveal some aspects of the nature of liquid metallic solutions. This was implied in the early work of Sieverts6 on the effect of alloying additions on the solubility of hydrogen in copper. Recent work by Bever and Floe7 has shown that in liquid copper-tin alloys the solubility of hydrogen changes abruptly at the composition of the intermetallic compound Cu3Sn. It is of considerable interest to determine whether liquid alloys of iron also have compositions at which the solubility of hydrogen exhibits a discontinuous or otherwise unique behavior. Among the various alloys of iron the iron-silicon system is important because of the presence of silicon in various structural alloy steels, transformer sheets, cast irons and special acid-resisting castings. The various grades of ferrosilicon, finally, cover almost the entire remainder of the composition range. Published information on the solubility of hydrogen in iron-silicon alloys is meager. The first values for pure liquid - iron were reported in 1910-1911 by Sieverts and Krumbhaar8 and by Sieverts.9 They found that 100 grams of iron absorbs 28 C.C. of hydrogen at 1550°C. and one atmosphere pressure, and 31 C.C. at 1650°C. In 1938 Sieverts, Zapf and Moritz10 published a value of 26.3 c.c. at 1550°C. Data on the solubility of hydrogen in liquid iron-silicon alloys and in liquid silicon

Jan 1, 1946

By L. D. Jaffe, D. C. Buffum

The importance of temper brittleness in alloy steels has long been realized in Europe. In the United States recognition of its importance has developed within the last several years. Many brittle failures encountered in parts made of alloy steel are undoubtedly attributable, wholly or in part, to temper brittleness. These failures have occurred particularly at low temperatures, under shock loading, and in the presence of notches, restraints and combined stresses. It has been almost universally accepted that plain carbon steels are not susceptible to temper brittleness. As a result, considerable effort has been expended in attempts to discover the manner in which alloying elements introduce temper brittleness. It is desired to raise the possibility that plain carbon steels are not only susceptible to temper brittleness, but are much more susceptible than alloy steels, in the sense that they embrittle much more rapidly. It is suggested that previous views, (that plain carbon steels are not susceptible), are based upon an erroneous interpretation of the experimental results. Interpretation of Previous Data For many years the standard criterion for susceptibility of a steel to temper brittleness consisted of comparison of the energy absorption, in a notched-bar impact test at room temperature, of specimens that had received two heat treatments.' One specimen (or group of specimens) was quenched, tempered, and quenched from the temper. The other specimen (or group) differed only in having received an embrittlement treatment, which might consist of a slow cool from the tempering temperature, or of an isothermal hold in the range 45w550°C subsequent to quenching from the temper. If the energy absorption of the specimen receiving the embrittlement treatment was lower than that of the specimen not given this treatment, it was said that the steel was susceptible to temper brittleness. If the energy absorptions were the same, it was said that the steel was not susceptible. Several investigators2J found that plain carbon steels showed negligible difference in energy absorption in such tests (at least when their manganese content was below 0.60 pct), and concluded that plain carbon steels are not susceptible to temper brittleness. Recently the deficiencies of the criterion mentioned above have been pointed out.'-= The criterion now generally used for susceptibility to temper brittleness retains the heat treatments used in the earlier scheme, but instead of the notched-bar impact tests being made only at room temperature, they are made over a range of temperatures, covering the transition from ductile to brittle fracture. If the transition temperature of the specimens receiving the embrittlement treatment is higher than those

Jan 1, 1949

By David L. Holt, Walter A. Backofen, Anwar-ul Karirn

ANNEALING the binary alloy, Mg-0.5 wt pct Zr in a hydrogen atmosphere results in extensive precipitation of zirconium hydride. The morphology of these precipitates has already been investigated.lm3 Squires, Weiner, and phillips4 found, following creep testing of the hydrided alloy at 450" and 500°C, that hydride denuded zones formed along grain boundaries that were aligned approximately normal to the tensile axis. Zone formation was attributed to diffusional creep by magnesium transport down the prevailing stress gradients.4'5 Recently, electron microprobe analysis by Karim, Holt, and Backofen6 showed the zones indeed to be zirconium-free and furthermore it was shown that in compression, zones formed along boundaries approximately parallel to the stress axis. Thus it was confirmed that the zones are formed by diffusional creep. Typical zone-formation is shown in Fig. 1. Karim, Holt, and Backofen also measured the con- tribution to the total strain, from diffusional flow, slip creep, and grain boundary shear: results showed that diffusional strain tends to saturate with increasing imposed strain, while grain boundary shear eventually becomes the dominant deformation mode. It was suggested in explanation that the precipitate-denuded zones are soft and easily sheared, such deformation contributing to the grain boundary shear measurement. A point to be emphasized is that the Mg-0.5 Zr alloy was not superplastic for the index of strain rate sensitivity of flow stress, m = a log log 6 was only 0.25. It was recognized that diffusional creep in a poly crystalline aggregate must be accompanied by boundary shearing.' The suggestion was that the non Newtonian-viscous character of diffusional creep in the Mg-0.5 wt pct Zr alloy is due to resistance to sliding of boundaries lying approximately parallel to the tensile axis.= The work described in the present note should be seen against the above background for it represents initial efforts to observe in a similar way diffusional creep in a superplastic alloy. Previous work with the ternary-alloy Mg-6 Zn-0.5 Zr, pellet extruded, showed it to be superplastic however it does not contain resolvable precipitates to act as internal markers for diffusional creep. Also the fine grain size of the alloy (0.5 p) made conventional metallography rather difficult. Solubility relationships in the Mg-Zn-Zr system are not well known, however making reasonable guesses about the probable phase diagram of the ternary, Mg-Zn-Zr, various heat treatments were attempted to produce hydride precipitation. Finally a 16-hr anneal at 495' in hydrogen was found to pro-

Jan 1, 1970

By Gerhard Derge, Arthur H. Grobe, Harold Markus

The high corrosion resistance possessed by tin under most circumstances, combined with its generally satisfactory appearance and useful physical properties, has led to many and varied uses for the metal. These uses have been partly limited by the fact that tin is an expensive metal, therefore many applications have been developed in which tin has been employed in combination with lead, either by coating, as in tin-lined collapsible tubes, or by the formation of alloys containing various proportions of tin-rich and lead-rich phases, as tcrne plate. A detailed knowledge of the corrosion characteristics of the tin-lead couple therefore is of general interest and has become specially important at the present time, when every effort is being made to conserve tin as much as possible. The present study has been limited to carbonate solutions with a pH range from 8.4 to 11.2 so that the results may be related to earlier work on the corrosion of tin and its alloys. 1-3,6 In these papers, the effects of a number of anion and cation additions to these solutions have been observed. Apparatus and Method The electrodes for the corrosion cell were cut from rolled sheet about 1/16 in. thick. The length of all specimens was held constant at 7 in., while the width was varied from M to 2 in. These electrodes were fastened to brass electrode supports, which were attached to rubber stoppers fitting into tall-type one-liter Pyrex beakers that contained the electrolyte. The lead electrodes were prepared from Omaha pig* and the tin was rolled from a slab of Chempur.† After cutting to size, the sheets were polished with No. I emery paper and cleaned with carbon tetrachloride. The edges, back and upper parts of the specimen were coated with a synthetic lacquer, which was supplemented with beeswax for the lead electrodes. The binding posts were coated with beeswax after the electrodes had been clamped. The pH of the electrolyte was controlled by adjusting the ratio of carbonate to bicarbonate. Approximately 600 ml. of electrolyte was used in each beaker. The entire assembly was placed in an oil bath thermostatically adjusted to operate at 30°C. + 0.1". Potentials were measured against a saturated calomel electrode connected to the cell by an agar-agar salt bridge. The carbonate solution used in the salt bridge was the same as that used in the corrosion cell. Currents were measured with a milliam-

Jan 1, 1942

By L. S. Reid, R. L. Huntington, Chen Chun Ku

The simultaneous adsorption of water and hydrocarbon vapor from natural gas by three grades of alumina has been studied at atmospheric pressure and temperature. Results of this investigation reveal that the presence of water vapor in the gas inhibits the adsorption of hydrocarbon vapor, although the presence of the latter does not have a pronounced effect upon the adsorption of water vapor. Adsorption of water-hydrocarbon mixtures from gas is divided into three phases. In the first, both water and hydrocarbon vapor are adsorbed; in the second, adsorption of water vapor proceeds while desorption of hydrocarbon takes place; in the third phase, the adsorbyt approaches complete saturation with respect to both water and hydrocarbon vapors. Both theory and experimental data can be applied to design and operation of commercial dehydration plants, and an illustration is presented. Introduction Dehydration of natural gas becomes increasingly important as the operating pressures employed in gas processing and transmission are increased above 500 ib. per sq. in. Gas produced from high-pressure wells is saturated with water vapor when it leaves the reservoir and it continues into the processing plant or transmission system in a saturated condition because of the substantial decrease in temperature due to expansion at the wellhead. Usually this gas is accompanied by liquid water and hydrocarbons that have condensed with the change in temperature and pressure. Without dehydration, gas temperatures must be held at relatively high levels to prevent solidification of gas hydrates. According to Hammerschmidt's data8 on the relationship of pressure to the freezing point of natural-gas hydrates, the minimum safe operating temperatures range from 55' to go°F. for pressures ranging from 500 to 3000 lb. per sq. in., respectively. Often it is difficult to maintain gas temperatures above the hydrate-freezing temperature because of climatic conditions, unless flow-line heaters are installed. Also, in processing gas for its gasoline content at high pressures, it is desirable to employ operating temperatures lower than the hydrate-freezing point. In distributing high-pressure gas, the large pressure drop from line pressure to town-gate pressure often prbduces sufficient cooling to freeze the regulators and disrupt consumer service. Therefore, it is highly essential to dehydrate high-pressure natural gas if smooth and economical operation is to be maintained at all times. Few published data are available on the simultaneous adsorption of water and hydrocarbon vapors. The literature contains many mathematical expressions for rate of adsorption in various systems but a rational correlation of the existing rate

Jan 1, 1944

By Charles R. L. Oder, Howard W. Miller

Approximately 5000 tons of zinc ore a day was mined during 1943 in the Mascot-Jefferson City district in East Tennessee. This ore came from the Kingsport formation, a part of the Knox dolomite, of Ordovician age. The Kings-port is composed of 350 to 400 ft. of limestone and dolomite. Thin cherts, sandy layers and shales are numerous. Frequently, the limestones are altered to crystalline dolomite. The Kingsport is divisible into four main lithologic zones. These divisions are illustrated in an accompanying table, which gives detailed sections of the ore-bearing beds as found in the mines and shows the exact positions of the various ore zones within the formation. Key beds are described and the practical applications of stratigraphy in mapping, prospecting and mining are discussed. Introduction The Mascot-Jefferson City zinc district is in Knox and Jefferson Counties, in the Great Valley of East Tennessee. It extends from Mascot, I3 miles northeast of Knoxville, to Jefferson City, about 30 miles northeast of that city. The American Zinc Company of Tennessee is producing from five mines in the district, in which it has operated for more than 30 years. The only other important producer is the Universal Exploration Co. The approximate daily production of the district in 1943 was 5000 tons of sulphide ore, grading from 2.5 to 6 per cent zinc. Small amounts of oxidized ore are mined intermittently. The Knox dolomite has been described by various geologists,'-' but no detailed descriptions of the rock sections revealed by mining have been published. Rock units are not conspicuously different and careful study is required to distinguish them. Nevertheless, familiarity with the stratigraphy of the mineralized zones is essential to successful exploration and extraction of the ores; therefore the purpose of this paper is to give detailed stratigraphic sections as measured in the mines, to discuss their important features and to show their relationship to the stratigraphy of the district. Generalized Section Table I gives the most characteristic general features of the major stratigraphic units. The formation names given in parenthesis are locally and widely used terms, the correlations of which are not necessarily established. For this reason they are put in quotation marks and are replaced by more restricted terms. The names "Mascot" and "Kingsport" were adopted from local towns. They were chosen jointly by Josiah Bridge, of the Federal Geological Survey, and the senior author for use in their separate unpublished manuscripts describing the Knox dolomite in East Tennessee. Descriptions of the type sections may soon be published. The name "Longview" was first applied by Butts6 in Alabama.

Jan 1, 1949

By Michael Tenenbaum, C. C. Brown

IN recent years, the importance of slag control in basic open-hearth operations has been universally recognized. To effect such control during the working period of the heat, methods have been developed to measure or estimate slag oxidation and slag basicity. While satisfactory rapid chemical methods have been developed to determine slag oxidation, no completely adequate method of evaluating basicity has yet been provided. The most generally accepted control methods of measuring slag basicity are based on visual estimates. While considerable benefit may be derived from such estimates, the need for some measurable indication of slag basicity has become increasingly apparent. In a recent paper, Philbrook and Jolly[$] suggested a promising technique for making the basicity determination. Their method consists of measuring the pH of a mixture of powdered open-hearth slag and distilled water. It was found that a relation could be established between the slag basicity and the alkalinity of the water mixture as measured by the hydrogen-ion concentration. The general procedure followed in making the measurements and the considerations involved in constructing the original curves are given in the paper of Philbrook and jolly and need not be repeated. It is the purpose of this paper to discuss some of the factors considered in applying the pH measurements to actual slag control and to present some of the results of its application. FACTORS INVOLVED IN MEASURING pH OF WATER-SLAG MIXTURES To facilitate the application of the pH control system, it was desirable that no alteration be made in the routine methods of sampling and crushing the furnace slag. Some of the factors considered before establishing a curve to relate slag basicity with the pH reading are reviewed individually in the following paragraphs. EFFECT OF COOLING RATE Under actual operating conditions there can be considerable variation in the tem¬perature of the piece of slag crushed for the pH determination. To determine whether variations in crushing temperature or in cooling rate would affect the pH reading, a series of four samples was prepared from each of two separate slags. These samples represented conditions far more extreme than would actually be encountered. To obtain these samples, a thick pancake of slag was poured. One piece of this pancake was crushed immediately after it had solidified. Another piece was water-quenched and then crushed. A third piece was allowed to air-cool to room temperature before crushing. The fourth sample was prepared from a chilled slag. This sample was poured onto a heavy inclined steel plate at the

Jan 1, 1945

By C. W. Green-Halgh

The accuracy with which grade and tonnage of a mineral deposit may be calculated from diamond-drill assays is dependent upon: (1) the reliability of core and sludge samples and (2) the validity of methods used in grade and tonnage calculations. Limitations imposed by drilling and sampling preclude elaborate methods of computation. In adjusting core and sludge assays the importance assigned the core and sludge samples may be based on either the respective weights recovered or the respective volumes represented by each. Only when core and sludge recoveries arc poor do discrepancies between adjusted assays calculated by these two methods develop, in which case the "weight" method gives emphasis to the core sample and the "volume" method gives emphasis to the sludge sample. When the sludge suffers classification within the drill hole, the weight method gives more accurate results; when the sludge sample suffers no classification, the volume method gives more accurate results. Any drilling campaign offers a compromise between desired accuracy on the one hand and expediency, limited time, money. or facilities on the other. Since the determination of grade and tonnage is an approximation at best, a proper basis for their computation requires a knowledge of the limitations imposed by all phases of work upon which the calculations depend A rational basis for coordination of these phases of work requires determination of: (I) the degree of accuracy desired, as a function of the object of examination; (2) the degree of accuracy attainable, as a function of the limitations imposed in the drilling and sampling program; and (3) the validity of method to be used in calculating grade and tonnage from core and sludge assays. This paper presents results of a comparison made between two commonly used methods of adjusting core and sludge assays, the assumptions upon which these methods are based, and the interrelationship of the phases of work upon which these calculations are dependent. Object of Examination The Purpose of prospecting any mineral deposit is to secure sufficient samples from which Ore grade and tonnage may be calculated. Any mine examination, preliminary or formal, has a definite purpose, although its scope may be limited or broad. The type of examination to be conducted is dependent, therefore, 'pan the reason for instituting the investigation; its scope and thoroughness are directly related to economic considerations. It is highly desirable, therefore, that before starting a drilling campaign a complete understanding of the extent of examination and desired degree of accuracy be determined as a means of simplifying the drilling program and unifying the relative degree of

Jan 1, 1946

By Russell G. Wayland

This paper gives the author's personal idea of the general viewpoint of the world's largest mica consumer, the U. S. Army, toward the supply, uses, and conservation of mica. However, to cover so broad a subject in a brief paper will require the dismissal of many phases with little or no mention. For example, it will be necessary to omit further reference to phlogopite or amber mica, even though amber block and splittings for certain spark plugs and commutator segments present some supply problems. This paper will deal entirely with muscovite, or white mica. Muscovite Mica Muscovite mica is available commercially in four general forms; namely, as block mica, as splittings, as washer punch, and as scrap mica.1 No strategic importance is attached to washer punch and scrap mica, even though scrap has found some use in military construction and in electrical ceramics. The use of washer punch as such has fallen off with the non-manufacture of household electrical appliances. Some qualities of block mica are also of little or no interest, but other qualities of block mica and all splittings are considered of vital importance. Army equipment requires large amounts of muscovite mica splittings in the form of built-up mica commutator segments and coil insulation in motors and generators. Other military items using significant amounts of muscovite splittings are transformers, switchboards, and blasting apparatus. Flexible mica tape, made from bookform or loose-dusted splittings cemented to paper, linen, glass cloth, and other backing, is widely used in coil insulation in heavy electrical equipment and in aircraft generators. All muscovite mica splittings come from India, principally because of the enormous amount of hand labor required in their preparation. In this emergency, the need for them was anticipated and large industry and government stocks were on hand, while shipments have continued to come by sea in spite of wartime hazards. With the possible exception of certain bookform splittings, no trouble is anticipated in supply. Accordingly, the remainder of this paper is devoted to block (or sheet) muscovite mica, including condenser film that is split from block. The Mica Problem Block muscovite mica is commercially classified into the following general qualitie3, beginning with the best quality: 1. Clear and Slightly Stained (C & SS). 2. Fair stained (FS). 3. Good stained (GS). 4. stained (s). 5. Heavy Stained (HS). 6. Black spotted. The ratio of relative commercial abundance in the present new supply of these micas is approximately 1 C & SS to 4 FS to ro GS to 14 S to whatever the

Jan 1, 1948

By Harold Markus, Gerhard Derge, Arthur Grobe

THE high corrosion resistance possessed by tin under most circumstances, combined with its generally satisfactory appearance and useful physical properties, has led to many and varied uses for the metal. These uses have been partly limited by the fact that tin is an expensive metal, therefore many applications have been developed in which tin has been employed in combination with lead, either by coating, as in tin-lined collapsible tubes, or by the formation of alloys containing various proportions of tin-rich and lead-rich phases, as terne plate. A detailed knowledge of the corrosion characteristics of the tin-lead couple therefore is of general interest and has become specially important at the present time, when every effort is being made to conserve tin as much as possible. The present study has been limited to carbonate solutions with a pH range from 8.4 to 11.2 so that the results may be related to earlier work on the corrosion of tin and its alloys.1-3,6 In these papers, the effects of a number of anion and cation additions to these solutions have been observed. APPARATUS AND METHOD The electrodes for the corrosion cell were cut from rolled sheet about 1/16 in. thick. The length of all specimens was held constant at 7 in., while the width was varied from ½ to 2 in. These electrodes were fastened to brass electrode supports, which were attached to rubber stoppers fitting into tall-type one-liter Pyrex beakers that contained the electrolyte. The lead electrodes were prepared from Omaha pig* and the tin was rolled from a slab of Chempur.† After cutting to size, the sheets were polished with No. I emery paper and cleaned with carbon tetrachloride. The edges, back and upper parts of the specimen were coated with a synthetic lacquer, which was supplemented with beeswax for the lead electrodes. The binding posts were coated with beeswax after the electrodes had been clamped. The pH of the electrolyte was controlled by adjusting the ratio of carbonate to bicarbonate. Approximately 600 ml. of electrolyte was used in each beaker. The entire assembly was placed in an oil bath thermostatically adjusted to operate at 30°C. ± 0.1°. Potentials were measured against a saturated calomel electrode connected to the cell by an agar-agar salt bridge. The carbonate solution used in the salt bridge was the same as that used in the corrosion cell. Currents were measured with a milliam-

Jan 1, 1942

SEC. 1. This Institute is incorporated under the Membership Corporations law of the State of New York; its corporate name is American Institute of Mining and Metallurgical Engineers, Inc.; and its objects are such as are stated in its Certificate of Incorporation. ARTICLE II SEC. 1. The membership of the Institute shall comprise four classes, namely: 1. Members; 2. Honorary Members; 3. Associates; 4. Junior Associates. All members shall be equally entitled to the privileges of membership, excepting that Honorary Members, Junior Associates, and Members and Associates whose residences shall be outside of the United States, Mexico, and Canada shall not be entitled to vote. Members and Associates residing within the United States of America, Mexico, and Canada, and not in arrears for dues, shall be entitled to vote in person at the meetings of the Institute, or, as hereinafter provided for, by letter ballot. SEC. 2. Members shall comprise all those persons who on the third Mon- day of February, 1918, were members of the Institute, and in addition thereto, all those thereafter elected or transferred into the class of Members. A person to be eligible for election or transfer into the class of Members must be at least 27 years of age and must have had at least six years' employment in the practice of engineering, mining, geology, metallurgy or chemistry, during at least three years of which he must have held positions of responsibility in one or more of these fields. Graduation from the scientific course of a college, approved by the Committee on Membership, shall be considered equivalent to two years' employment, as required in the previous sentence. Employment as a teacher of engineering, mining, geology, metallurgy or chemistry, if in direct charge, may be considered a position of responsibility as specified in the second paragraph. Persons employed in research or any scientific literary work or in teaching in the scientific departments of colleges, approved by the Committee on Membership, who at the same time are engaged in consulting or in the active practice of mining, geology, or metallurgy, shall be entitled to consider the time so spent in active practice as equivalent to an equal length of time of employment in positions of responsibility, provided the work done or the positions held seem to the Committee on Membership to warrant the equivalency. The requirement of three years' employment in positions of responsibility may be waived by the Committee on Membership in the case of persons who have done notable original work in mining, or metallurgy, or have won distinction by research or investigations In one or more of these subjects.

Jan 1, 1928

By C. W. Phillips, R. S. Busk

With most cast metals the grain size may vary within wide limits, depending upon the conditions at the moment of freezing. These conditions are subject to control in magnesium-base alloys, by proper melting and superheating techniques, enabling production of quite uniform and fine-grained castings, almost independent of section thickness. However, such variations of grain size as do exist, in common with all metals, are reflected in corresponding changes in mechanical properties. It is the intent of this paper to present data giving the relationship between grain size and mechanical properties. Data are also included on the combined effects of grain size and micro-porosity. In addition, a short discussion of factors influencing the grain size of sand castings is included. Measurement OF Grain Size By grain size is meant the statistical distribution of volumes occupied by the individual crystallites in a metal section. Since this is almost always impossible of direct measurement, several methods of estimating and expressing the size have been evolved. Most exact methods make use of the microscope. This involves study of a single plane cut at random through the metal. What is seen in the microscopc are polygons, each the cross section of a grain. The diameters or areas of these polygons are then measured and the grain size is expressed as an average diameter, number of grains per unit area, average area per grain, or, rarely, average volume per grain. Rutherford, Abom, and Bain3 have discussed extensively the errors involved when using a plane section to estimate volume. They clearly point out that the tendency is to underestimate the true grain size because of the nature of the measurcment. The A.S.T.M. recommends that measurement be made by comparison with a standard chart, by means of Jeffries' planimetric method4 or Heyn's intercept method. The Society recommends that the notation be in terms of the number of grains per unit area (as is the grain-size number used for steel) or as an average diameter, expressed in inches or millimeters (as for copper and brass). The method of measurement used for this study was comparison with a standard chart, which has been described by P. F. George.5 The chart was constructed by photographing at Ioo diameters a uniform specimen with an average grain diameter of 0.003 in. The average diameter of this specimen was determined by numerous measurements, using both the Jeffries and Heyn methods. The other grain sizes were then obtained by appropriate enlargemcnt of the master sample. Careful comparison of the chart method with other methods on identical samples indicates that though the differences be-

Jan 1, 1945

All the TECHNICAL PUBLICATIONS and CONTRIBUTIONS published in 1941 are available at Institute headquarters, unless otherwise noted They are also on file in many public, university and technical libraries and, when so indicated in the list, may be found in the TRANSACTIONS TECHNICAL PUBLICATIONS in Classes A-Metal Mining, 13-Milling and Concentration, H-Industrial Minerals, and I-Mining Geology are distributed in MINING TECHNOLOGY, which is issued every other month Technical Publications in Classes C-Iron and Steel Division, D-Nonferrous Metallurgy and E-Institute of Metals Division are distributed in METALS TECHNOLOGY, which is issued twice quarterly TECHNICAL PUBLICATIONS in Class G-Petroleum Division are distributed in PETROLEUM TECHNOLOGY, which is issued every other month TECHNICAL PUBLICATIONS in Classes F-Coal Division, J-Mineral Industry Education Division, K-Mining Administration, and L-Geophysics, are issued as separate pamphlets An Institute member is entitled to one copy of any printed TECHNICAL PUBLICATION or CONTRIBUTION Copies of TECHNICAL PUBLICATIONS listed have been mailed to members of the Institute according to their registration by classes CONTRIBUTIONS and other TECHNICAL PUBLICATIONS will be sent upon request A member may purchase an additional copy of a TECHNICAL PUBLICATION or a CONTRIBUTION at one cent a page, minimum charge, 25¢ Nonmembers may purchase any CONTRIBUTION or a TECHNICAL PUBLICATION of the F, J, K, or L classes at the same rate, but the nonmember price per copy for METALS TECHNOLOGY, MINING TECHNOLOGY or PETROLEUM TECHNOLOGY is $1 25 domestic, $1 35 foreign countries. TECHNICAL PUBLICATIONS (separate pamphlet form), $2 per annum domestic, $2 50 foreign. METALS TECHNOLOGY, $7 per annum domestic, $7 80 foreign (Iron and Steel Division and Institute of Metals Division ferrous and nonferrous papers) MINING TECHNOLOGY, $6 per annum domestic, $6 60 foreign (metal mining, milling and concentration, Industrial Minerals Division, and mining geology papers) PETROLEUM TECHNOLOGY, $6 per annum domestic, $6 60 foreign Bound volumes have been mailed to members that have requested them, and MINING and METALLURGY Is mailed each month A member is entitled to one volume a year on his membership and he may purchase for $2 50 one copy of a volume not already received, additional copies of the same volume, $5 Nonmembers in the United States may purchase the volumes listed at $5 each, outside of the United States and its possessions, $5 6o Extra single copies of MINING AND METALLURGY, 25¢ current issue, back numbers 500 each to members, to nonmembers 50¢ current issue and $1 each, back issues Subscription price to nonmembers and to members for extra copies, $3 per annum domestic, $4 00 foreign.

Jan 1, 1941

By R. F. Janke, J. F. Bossler

Introduction The commercial use of ion exchange resins to recover uranium evolved in the decade following 1950 when significant efforts were made to recover this vital element economically and efficiently from low grade ores. It was discovered that in both acid and alkaline systems, uranium exists as an anionic complex. This led to the application of anion exchange resins to concentrate and purify the uranium product. While this is the simplest statement of what an ion exchange resin does in the recovery of uranium, it should not be forgotten that the industry is continuing to evolve new methods in mining and processing which affect ion exchange operation. The inception of solution mining, the use of expanded bed ion exchange columns and the development of continuous ion exchange systems represent several examples of this continuing evolution in the industry. Throughout all of the changes in equipment designs and variations in solution compositions, the purpose of the ion exchange resin remains the same - to concentrate and purify uranium. Ion Exchange Resins When evaluating ion exchange resins for a uranium recovery project, the task that faces the chemist or process metallurgist is an assessment of the efficiency and, therefore, the economics of the various candidate resins for a given project. This assessment should include consideration of both physical factors such as particle size, density, hydraulic expansion and pressure drop as well as chemical factors such as the uranium loading and elution characteristics. For any given application, the differences in the physical and chemical behavior of ion exchange resins are a function of the conditions used to manufacture those resins. Therefore, an understanding of the way in which manufacturing variables affect resin behavior is important. Since most uranium recovery projects are concerned with recovery of the anionic complexes of uranium using anion exchange resins, this discussion will be restricted solely to the family of anion resins. The majority of the ion exchange resins used in commercial recovery operations look similar to the resins shown in Figure #1. [ ] Most of these materials are based on a styrene- divinylbenzene copolymer. The liquid monomers, styrene and divinylbenzene, are charged to a co-polymer reactor containing water. The water insoluble monomers are then mixed with the water to suspend oil-like droplets of the monomer mixture in. the water. The entire reaction mixture is then heated causing the monomers to polymerize into sol id thermoset plastic spheres. The spherical nature of the particle, the particle size distribution and the primary crosslinking level are fixed in this step in the production process. Figure 2 is a simplified illustration of this step of the process. [ ]

Jan 1, 1979

James Douglas will long be remembered as a distinguished mining engineer and metallurgist, as a scientist with broad vision, as an executive whose understanding of practical problems coupled with his knowledge of men and affairs enabled him to weld together great mining interests and to their service build railroads and bring power. More, he will be recalled as a philosopher and a writer of charm, a historian of no mean order, and one whose catholic tastes and enthusiasms led him into the fields of education, medicine and theology. His aim was to possess that which he considered made life worth while—friends and effectiveness in whatever task he undertook. In this aim he was successful to a degree exceeded by few, as thousands of his friends and associates could and can testify. Dr. Douglas was born on November 4,1837, at Quebec, Canada. His father, James Douglas, Sr., was a prominent physician and the leading surgeon of Canada. He also established the first retreat for the insane in the Dominion, the Quebec Lunatic Asylum, to which he devoted his services for years; The son followed in the footsteps of his father and studied medicine, not only in Canada but also in Scotland and in Germany. He entered the University of Edinburgh in 1855 but after two years at that institution returned to Canada and was graduated from Queens university at Kingston, Ontario, .with the degree of Bachelor of Arts. Later he went to Lava1 University, Quebec, and subsequently became professor of chemistry at Morrin College, Quebec. After he was graduated—at the time he considered his formal education completed—he traveled with his father in Europe and in the Orient; visiting Egypt, being especially interested in that country, several times. They gathered together an important archaeological collection which later was donated by them to the Metropolitan Museum of Art in the city of New York. James Douglas was also greatly interested in photography, a hobby in which he made use of his chemical knowledge. The writer can remember distinctly the descriptions he gave more than forty years ago in Arizona of the difficulties he encountered with the old wet photographic plates, especially while traveling in Egypt, when he prepared and used his own chemicals. In his humorous manner he told how he once discovered, in the nick of time, the nurse preparing to give the baby in the party a rub-down, using for that purpose the white, limpid

Jan 1, 1934

By D. R. Miller

Internal friction and elastic modulus variations in electrorefined titanium, iodide refined titanium, and alloys of the latter material with oxygen, nitrogen, aluminum, and zirconium were investigated. No oxygen peak was detected with electrorefined titanium but, provided precautions were taken to prevent increases in background damping, an oxygen peak at about 410°C could be resolved with each of the other materials. An additional partially resolved peak was observed at 500°C in a Ti-N alloy. An anomaly in the variation of rigidity modulus with temperature was observed. Possible mechanisms for the formation of any oxygen peak have been discussed. PRATT, Bratina, and Chalmersl investigated the internal friction of commercial purity titanium and alloys of this material containing 1.5, 3.5, and 4.5 at. pct O. With commercial titanium the internal friction curve consisted of two components, a background which increased steadily with temperature and a peak at about 600" C which was due to grain boundary relaxation. In the Ti-O alloys, however, an additional internal friction peak was observed at 430" to 450°C and, since this peak increased in height as the oxygen content was increased, it was thought to be associated with the presence of oxygen. The diffusion of oxygen in titanium at temperatures between 300" and 500° C is believed to have marked effects in its tensile properties2'3 and the present internal friction measurements were undertaken to obtain further information on this diffusion, using material of higher purity than that of Pratt et d. and an apparatus of very much greater sensitivity. In the course of the investigation a number of important limitations on the work of Pratt et al. were revealed and results have been obtained which emphasize the need for ensuring that in this type of experiment, internal friction is independent of strain amplitude and that the values obtained are reproducible. 1) MATERIALS AND APPARATUS The basis material from which the majority of the specimens was prepared was iodide-refined titanium, the major impurities in which were oxygen and nitrogen—the metallic impurities being present at concentrations less than 0.001 at. pct. The hardness of this material after arc melting, forging, and swaging to rods 1/4 in. diameter was Dph = 110. Specimens 10 in. long and 0.020 in. (0.51 mm) diameter were prepared from these rods by further swaging and wire drawing and were finally annealed in vacuo (5 x 10-6 mmHg) for 24 hr at 800°C. The oxygen alloys were prepared from iodide-

Jan 1, 1962

By Will Mitchell, T. G. Kirkland, C. L. Sollenberger

BENEFICIATION of a Korean scheelite ore has been studied during the past year in the Basic Industries Laboratory at Allis-Chalmers Manufacturing Co. A flowsheet has been recommended including flotation, gravity separation, and a final cleaning by a magnetic separator. The investigation was continued in the field of flotation in order to establish the effect of certain variables on recovery and grade of rougher concentrates. The results of this investigation are recorded here. Mineralogy The scheelite ore was obtained from Korea and was mined from the Sang Dong deposit. This deposit is described as lying in gently dipping metamorphosed sedimentary beds of Cambrian age.' The metamorphism was probably either metasomatic replacement or recrystallization, or both, with subsequent hydrothermal deposition. Igneous bodies in the form of granite porphyry have been found within 7 km of the main shaft and are considered to be a possible source of the mineralizing solutions. The Myobong formation, the host for the Sang Dong deposit, was laid down in middle Cambrian times and consists of series of mudstone, siltstone, shale, and marl, with local stratification of mica schists, hornfels, and tactites. The scheelite is found in quartz bands in the tactites. Although there are six of these bands, only one, the "main bed" averaging 1.75 pct WOs, has been mined to any extent. The ore sample as received in the laboratory was the product of a cone crusher and was all —2 in. The rock appeared to be even textured, medium to fine grained, and gray green in color. No scheelite could be recognized by the unaided eye. However, under ultraviolet light of 2537 A, the scheelite fluoresced and could be distinguished from the gangue. Under the black light, the scheelite showed no definite vein structure but was disseminated throughout the specimen. The raw ore had a specific gravity of 2.96 and weighed about 125 lb per cu ft at —20-mesh Tyler. The —2-in. material was stage crushed through 20-mesh, and samples were cut for mineralogical, chemical, and spectrochemical analyses. Several polished sections were cut from hand specimens. Figs. 1 and 2 show quartz to be the matrix for scheelite. It was reported by Kim2 that the greatest scheelite concentration in the mine is found with a high concentration of quartz and a decrease in the abundance of garnet. Diameters of scheelite particles ranged from 1.2 mm down to less than 50 microns. Spectrochemical analysis showed the ore to be high in aluminum, bismuth, calcium, iron, magnesium, manganese, silicon, tungsten, and with lesser amounts of beryllium, chromium, lithium, sodium, and titanium. Chemical assays showed the —20-

Jan 1, 1952