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By Zhang Yongzhu

In hydrometallurgical processes of PGMs separation and refining, differences between 1-PGMs (Ru;Rh;Pd) and h-PGMs(Os;Ir;Pt) in thermodynamics and kinetics have been observed. The successful practice in the separation and refining of PGMs in China, is mainly based on the following two kinetically extraction sequences of: (1) for the extraction of PGMs complexes in different configurations with coordination mechanism (AuCI,) -> (MCl6)2-> (MCl4 )2-> (MCI6) 3- , and the substitution rate for h-PGMs complexes with higher effective nuclear charge Z' is much more slow than that of I-PGMs. and (2) for the extraction of PGMs in different configurations with oxonium (or ion -exchange) mechanism (AuCl4)-> (MCl4)2--> (MCl6)2-> (MCl6)3- and the extraction of h-PGMs complexes with low surface charge density is more fast than that of I-PGMs complexes. In view of atomic structure theory, the similarity of atomic radii and chemical properties and difficult separation of PGMs resulted from the Lanthanide Contruction between 5th period (1-PGMs) and 6th period (h-PGMs). The differences between h-PGMs and 1-PGMs are due to the loss shielding of 4f subshells on 5d electrons for h-PGMs with higher nuclear number, which makes h-PGMs have a higher Z' (effective nuclear charge) and strong attraction for outer space electrons. As a result, h-PGMs metals and complexes are thermodynamically more stable and kinetically more inert than the corresponding 1-PGMs. The differences between h-PGMs and 1 -PGMs in aspects of elements properties, complexes, hydration, substitution and redox reactions , are discussed.

Jan 1, 1993

By V. F. Parry

The major industrial uses of char or semicoke produced by low-temperature carbonization of coal4/ are as fuel for generating electric power, for blending with metallurgical coking coal as a substitute for low-volatile coals, and for gasification to produce synthesis gas for chemical purposes. This paper discusses various methods for carbonizing coal, emphasizing processing of the noncoking coals to produce char for thermal power-plant fuel and for blending with metallurgical coking coals and tar for chemical use. Low-temperature carbonization is a relatively simple processing step involving heating coal to about 900° to 1,200° F. to decompose the coal into 4 main products: (1) Semicoke or char; (2) complex, partly oxygenated liquid hydrocarbons or tar; (3) fixed gases; and (4) water. If the coal is heated rapidly under conditions that prevent decomposition of the primary products, 68 to 87 percent of the net heat in the raw coal is left in the char and 10 to 23 percent of the potential heat appears in the primary tar. Fixed gases represent approximately 7 percent of the heat and approximately 2 percent is lost or dissipated in the reactions of decomposition. Considering the different ranks of coal in the United States, the yield of tar will vary from about 9 to 44 gallons per ton, therefore it is important that each coal be carefully considered if it is to be carbonized for industrial use.

Jan 1, 1955

By Pingchao Ke, Zhihong Liu

"To overcome the problem that scoroditeis not stable in neutral and alkaline solutions, we proposed and investigated a synthesis method of scorodite coated in-situ with hydrated ferric oxide in the Fe(II)-As(V)-H2O system at the initial Fe(III)/As(V) molar ratios larger than 1.0.The synthesis was carried out at 90?,pH 1.5 under atmospheric pressure. During the synthesis, oxygen gas was conducted and bubbled into the system to oxidize Fe(II) ions into Fe(III)ions, and Na2CO3aqueous solution as neutralizing agent was added controllably into the system for keeping the pH constant at 1.5. In this study, three samples of scorodite were synthesized at the controlled initial Fe(II)/As(V) molar ratios of 1.0, 2.0 and 3.0, respectively. The characterizations of the samples by HRTEM, TEM/EDX, and chemical composition indicated that the particle surfaces of scorodite synthesized at the initial Fe(II)/As(V) molar ratio of 2.0 and 3.0 were coated in situ by a film of hydrated ferric oxide with the thickness of several nanometers, while the sample synthesized at the initial Fe(II)/As(V) molar ratio of 1.0 was uncoated scorodite. The TCLP and long-term leaching for the toxicity characteristic of the samples showed that scorodite coated in situ with hydrated ferric oxide was stable in a wide pH range from 3.0 to 10.0, with the arsenic concentrations in the leaching solutions less than 1.0mg/L. Nevertheless, uncoated scorodite was unstable under the conditions from weak acidity to alkalinity, with the arsenic concentrations in the leaching solutions larger than 5.0 mg/L.INTRODUCTIONArsenic pollution is a challenge for environment and health and has been an important issue for scientists (Hopkin, 1989).Arsenicis commonly associated with ores or concentrates of nonferrous metals, mainly as independent arsenic bearing minerals such as arsenopyrite (FeAsS), tennantite(Cu12As4S13), enargite (Cu3AsS4), cobaltite (CoAsS), and gersdorffite (NiAsS), realgar (As2S2), orpiment(As2S3), etc.(Matschullat, 2000; Mandal & Suzuki, 2002; Long & Peng, 2012). In the nonferrous metallurgical processes, arsenic is enriched mainly in such arsenic bearing materials as various flue dusts, residues, and anode slimes, which results in the accumulation of arsenic in the system owing to the circulation of those arsenic-bearing materials back to the system and the pollution to the environment (Harris, et al, 2003).In addition, the utilization of arsenic is limited and has been decreasing owing to its toxicity and carcinogenicity. Therefore, arsenic has to be removed from those arsenic-bearing materials and discarded safely (Dutrizac & Jambor, 1988; Monhemius & Swash, 1999; Drahota & Fillippi, 2009).In this case, how to immobilize arsenic has become a difficult problem which must be solved. Among the methods of immobilizing arsenic which have been proposed and investigated, immobilizing arsenic into a stable mineral to fix it, has been realized as a promising method and becomes a research focus(Dutrizac et al, 1987; Dutrizac & Jambor, 1988; Demopoulos et al, 1995; Fujita et al, 2008a; 2008b).Scorodite has been known as one of the best minerals for immobilizing arsenic, owing to its high stability under weak acidic condition, the arsenic content as high as 32wt%,and good crystallinity benefiting the separation of solid to liquid(Daivid et al, 1999; Zhu & Merkel, 2001). Scorodite can be synthesized from arsenic containing solutions under both hydrothermal and atmospheric conditions, and a lot of work has been done on the synthesis of scorodite and its leaching stability characterization (Filippou & Demopoulos, 1999; Gomez et al, 2011).Two plants for the immobilization of arsenic as scorodite have been putin to operation in Chile and Japan, respectively (Filippou & Demopoulos, 1999; Amir et al, 2016)."

Jan 1, 2017

By B. W. Gandrud

[The Bureau of Mines is conducting an extensive investigation of coal preparation in the Alabama coal fields in cooperation with the University of Alabama coal-mine operators. In this investigation the drainage characteristics of typical coals from the Warrior and Cahaba fields were studied]

Jan 1, 1941

PRESIDENTS DAVID THOMAS 1871 R W RAYMOND 1872-1874 A L HOLLEY1875 ABRAM S HEWITT 1876 T STERRY HUNT 1877 ECKLEY B COXE 1878 - 1879 WILLIAM P SHINN 1880 WILLIAM METCALF 1881 RICHARD P ROTHWELL 1882 ROBERY W HUNT 1883 JAMES C, BAYLES 1884-1885 ROBERT H RICHARDS 1886 THOMAS EGLESTON 1887 WILLIAM B POTTER 1888 RICHARD PEARCE 1889 ADAM S HEWITT 1890 JOHN BIRKINBINE 1891-1892

Jan 1, 1923

By James R. Hein

Manganese nodules form at the sediment surface of abyssal plains throughout the global ocean at water depths of about 4000-6500 m. The nodules form a continuum from purely hydrogenetic (all metals from seawater) to purely diagenetic (all metals from sediment pore waters), which will determine which metals of potential economic interest are enriched in the nodules. Another important factor in metal enrichment is whether diagenesis in the bottom sediment is oxic or suboxic. There are several nodule fields in the deep ocean that have received much attention with regards to economic potential, the most important being the Clarion-Clipperton zone (CCZ) in the NE Pacific, where the International Seabed Authority (ISA) has signed 12 contracts for exploration areas, each spanning 75,000 square kilometers. Those nodules are rich in nickel (mean 1.3 wt. %), copper (mean 1.1 %), and manganese (28%), with moderate amounts of cobalt (mean 0.2%), molybdenum (587 g/t), and lithium (129 g/t). A conservative estimate is that there exists 21,100 million dry tonnes of nodules in the CCZ, yielding more manganese, twice the nickel, three times the cobalt, and four times the yttrium than the entire land-based reserve base (economic plus marginally economic plus subeconomic reserves) for each metal. Total rare-earth elements (REEs) as oxides average 0.09% in CCZ nodules, a potential byproduct even at that grade because the heavy REE complement averages 26%, compared to less than 1% for the large land-based carbonatite REE deposits. The price for HREEs is much greater than for the light REEs. For comparison, the REEs in deep-ocean ferromanganese crusts are 3 to 5 times greater than nodules and the HREE complement averages 18%. Of the 12 CCZ contracts, 7 are with States (China, France, Germany, Japan, Korea, Russia, and a group of States (IOM); and 5 are with companies: G-Tec Sea Mineral Resources NV, Nauru Ocean Resources Inc. (NORI); Tonga Offshore Mining Ltd (TOML), UK Seabed Resources Ltd (Lockheed UK), and Marawa Research and Exploration Ltd. Three other nodule fields that have received attention are in the Peru Basin, which has nodules very rich in manganese (34%) and lithium (mean 311 g/t), the Penrhyn Basin (Cook Islands Exclusive Economic Zone), with nodules very rich in cobalt (mean 0.4%); and the Central Indian Ocean Basin (CIOB), where India has an exploration contract with the ISA. CIPB nodules have mean nickel, copper, and manganese contents of 1.1%, 1.0%, and 24% respectively.

May 1, 2013

By Peter E. Halbach, Andreas Jahn

"Co-rich ferromanganese crust deposits exist on slopes, summits and platforms of seamounts and guyots throughout the global oceans, where deep-sea currents have kept the seafloor structures more or less free of sediment for millions of years. They form by direct precipitation from cold seawater under more or less oxic conditions and consist of thin layers (2 up to 25 cm thick) covering hard substrate rocks in water depths of 800 to 5000m (Halbach and Marbler, 2009; Hein et al., 2000). Besides Mn these crusts contain interesting concentrations of minor elements (Co, Ni, Ti and Cu) and trace elements (Mo, W, Te, Ga, Pt and REEs), thus they represent significant metal deposits and promise potentially valuable additions to the world’s metal resources.The prospects for mining of this marine type of metal deposits largely depend on the grades and the scale of the potential ore resources. However, only a few percent of existing seamounts and guyots have been mapped and sampled in detail, most of them in the Pacific Ocean. Therefore, a model to estimate the geological resources based on the global seamount catalogue of Wessel (2001; revised: Wessel et al., 2009) and the empirical parameters which control the metal composition and distribution was developed."

Jan 1, 2017

By H. A. Guess

For a number of years I have used for the commercial wet assay of lead generally the ammonium molydate, and occa-sionally the ferrocyanide method. These well-known methods need no detailed description here. In the ore-selling and ore-buying establiahments of the West, 90 per cent. of all wet lead-assays are made by one or the other, and at least nine-tenths of this proportion by the molybdate method. A procedure so well-established must have merit; and, in

Jan 1, 1905

R. F. WOOD,* Sandusky, Ohio.-I made a few tests of gun-metal specimens, after I noticed the results on quenching -reported by the Bureau of Standards. The data of one such test are given herewith. The bars were heat treated and quenched before they were machined, and in all cases they were brought up to 700° or 800°. They became extremely brittle,, showed almost no elongation, except such as was caused by the failure of the pieces to fit together after they were pulled, and the tensile stength was reduced from around 35,000 to about 13,000 lb. per sq. in. In addition, the weakening effect of the quenching seemed to be almost as marked when the bar was allowed to slowly air-cool from red to black, and then quenched, as it was by quenching directly from the red heat. Test Bars.-Rough size, 9/16 in. diam. over test section, grips 13/16 in. diam. Cast two in a flask, one on each side of a block 8 by 4 by 1 in. and fin-gated thereto from the grips but not from the test section. Poured with flask in inclined position, with gate to lower end of block and riser from upper end of each test bar. Bars were machined to ½ in. over the test section, after heat treatment. Casting the Bars.-Charge of 1500 lb. consisting of 400 lb. of new metals and 1100 lb. of G turnings and scrap was melted in open-flame oil furnaces and then poured into a 1-ton ladle. From the ladle 150 lb. was poured into a preheated No. 50 crucible, land from this the flasks of test bars were poured. The six flasks are indicated below by the numbers 1 to 6 and the bars in each flask by the letters a and b, thus 4a and 4h, for instance, were the two bars in flask No. 4.

Jan 12, 1919

By John J. Friel

Digital imaging systems are particularly useful in microscopy, because they make it possible to extract information not readily accessible by manual methods and to display that information clearly. Computer-aided imaging systems analyze, process and compare images, and of these, image analysis is most useful in materials science. Image analysis quantifies the microstructure by making measurements on the entire field or by measuring the size and shape of features individually. Even true surface area can be calculated. Modem image analyzers make thousands of measurements in seconds, leaving the investigator to interpret the data and relate them to process and material properties. Image processing, which may be necessary to prepare an image for analysis, includes everything from simple contrast transforms and kernel filters to complicated processes such as grain boundary reconstruction using artificial intelligence. An example of image comparison is point-by-point screening of X-ray maps of different elements to extract phases. In all of these operations, the computer makes a large number of measurements in seconds and returns information that could not be realistically obtained by manual methods.

Jan 1, 1992

By John F. Wiss

A series of controlled experiments was conducted at four surface coal mines to study the effects of certain blast parameters upon the ground and air vibration. Preliminary scale-model blasts were conducted at a quarry to provide basic data. It was found that the amplitudes of the ground and air vibration were controlled by the maximum explosive weight per delay. Either cube root or square root scaling could be used for the seismic amplitudes, and cube root scaling could be used for the overpressure amplitudes. Both amplitudes were not significantly affected by the total charge weight per blast, the attitude of the boreholes, or the charge length or diameter. The overpressure amplitudes were affected by the charge depth, the use of cover over surface detonating cord, and the use of adequate stemming. The length of the delay intervals and the spacing of holes were important in determining the potential for reinforcement of the amplitudes in certain directions from the blasts. In downwind directions from the blast, the attenuation of the overpressure with distance decreases. Surface terrain t did not significantly affect the overpressure amplitudes within the range investigated. The type of overburden affects the generation of both amplitudes and the propagation of the seismic amplitudes. Spectral analysis of the ground and air vibration is reported. A bibliography of pertinent literature is included as an appendix. A scaled distance of 300 ft/lb1/3 should produce a peak particle velocity of less than 1 ips and an overpressure of less than 128 dB linear peak. For square root scaling, a scaled distance of 75 ft/lbl/2 should limit the ground vibration to less than 1 ips.

Jan 1, 1978

By A. Wahab Khair, Nagendra P. Reddy

"This paper presents an analysis of preliminary tests on the effect of in-situ and operating parameters on fragmentation of coal using a specially designed unique automated rotary coal cutting simulator (ARCCS). In these tests coal blocks with an approximate dimension of 18 in. x 15 in. x 6 in. (45.7 cm x 38.l cm x 15.2 cm) were first. subjected to confining pressures, equivalent to in-situ conditions. Such. blocks were then cut by the cutting head of the ARCCS, thus simulating the action of the continuous miner in underground coal mining. During the tests under a particular set of in-situ and operating parameters a number of other parameters such as 1) penetration of bit into coal, 2) penetration resistance (thrust and cutting pressures), 3) rotating velocity of cutting head, and 4) acoustic emission activity in the coal block were monitored. After each cutting cycle the fractured surfaces were photographed and a velocity survey was conducted by using a sonic technique. At the end of each experiment the cutting paths of the bits in coal were photographed using an optical microscope with a camera attached to it. Furthermore, the coal fragments were collected in bags using a vacuum cleaner. These fragments were then sieved for size distribution analysis. The results of the preliminary tests indicated that underground coal cutting can be simulated in the laboratory and the effects of the important parameters, i.e. operating and in-situ parameters, can be studied successfully. INTRODUCTIONThe continuous-mining machines which were introduced in the 1950's now account for more than half the production of coal from underground mines. Unfortunately, these continuous miners, which were designed for increased productivity, have also increased the concentration of respirable dust in mines. As a result, the Federal Coal Mine Health and Safety Act of 1969 was enacted to enforce on the coal operators that the airborne respirable dust not exceed 2 mg/m3, and was intended to reduce the incidence of coal workers pneumoconiosis. This plus the other aspects of the legislation and the subsequent monitoring and enforcement by MSHA made it very imperative that the coal operators provide a relatively healthier and safer working environment for the coal miners. Since 1970, the Federal government has paid over 11.7 billion dollars to more than 470,000 miners with coal workers pneumoconiosis and their survivors (1). These regulations, coupled with the assessment of the continuing burden on miners, the mining industry and taxpayers appear to have provided an impetus for the mining .community towards comprehending the different parameters that influence dust generation and entrainment."

Jun 1, 1988

By Michael R. Cartwright

The Gold Acres outcrop was located by Lee Lakin in 1922, according to Mr. H. W. Treweek. There was no activity, however, until 1935, when prospect drifts and pits penetrated the deposit. It was then drilled by the Willow Creek Mining Company. Beginning in the late 1930s and continuing to the late 1940s more than 150 churn drill holes were drilled in the Gold Acres area. From this drilling came what is now known as the London Extension pit. Only oxidized ore amenable to cyanide vat leaching was mined during this time. Our records indicated that this period of mining removed some 1.4 Mt (1.5 million st) of ore at an average grade of 0.006 kg/ t (0.2 oz per st). Union Pacific and Newmont Mining Company worked in the area prior to acquisition by the Cortez Joint Venture. Union Pacific drilled a number of core holes in the area. The unoxidized nature of the ore, small tonnage, and low grade undoubtedly prevented mining at this time. From these indications of mineralization shown by previous companies, the Cortez Joint Venture developed and mined 2 Mt (2.4 million st) at 0.005 kg/t (0.15 oz per st) in the Gold Acres pit. This pit is located immediately southwest of the older London Extension pit. Cortez Gold Mines has continued to drill to the west and south of these pits along the downdip continuation of the former ore bodies. The downdip extension is unoxidized and more metallurgically difficult than the normal Carlin type ores, but, more than 2.4 Mt (2.7 million st) have been outlined. It depends now upon the gold price and milling costs to turn this mineralized area into an ore body. A possible lesson to be learned from this deposit is that continued mining success depends upon an ongoing adequately funded exploration-development-metallurgical research program. These three disciplines must always be present to locate the mineralization and to turn this mineralization into ore. [ ]

Jan 1, 1985

By Richard H. Follis

Activated carbons used for precious metal recovery from carbon-in­pulp (CIP), carbon-In-leach (CIL) and carbon-in-column (CIC) circuits often become fouled with Inorganic precipitates (i.e., CaCOa, CaS04, SI02), and adsorbed organics (I.e., petroleum distillates from lubricants, dissolution products from wood) (1,2). These contaminants occlude carbon pore structure, such that diffusion controlled adsorption and desorption (elution) of Au(CN)2-and Ag(CN)2· are lmpeded(3,4l. Thus, after only short exposure to the hydrometallurgical environment, the characteristic carbon activity is reduced(5l. By frequently regenerating circuit carbons, activity losses associated with fouling can usually be minimized. Regeneration typically Involves (not necessarily Is this order): 1) elution to remove adsorbed ionic species (e.g., until they are removed from the carbon pore structure, Au(CN)2" and Ag(CN)2-are contaminants )(6l; 2) acid washing with 3-15% (wt/wt) hydro­chloric acid, to dissolve soluble Inorganic precipitates such as CaC03; 3) neutralization and/or water rinsing to remove residual acid; 4) thermal regeneration at 350-650 °C to remove adsorbed and/or pyrolyzed organ­ics; and 5) screening to remove fine carbon particles produced by Impaction and abrasion in the various stages of the hydrometallurgical circuit (i.e., adsorption, elution, and regeneration). The overall process Is purposed to reopen the circuit carbon pore structure, and to maintain the activity and qualities of virgin (new) carbon(7,8l. While most CIP, CIL and CIC operators regenerate circuit carbons, few evaluate the effect of the process on carbon quality in a systematic way. Process control usually Involves Iterating critical regeneration parameters such as: acid concentration; time frames for acid washing and water rinsing; and temperature and residence time for thermal regeneration. Carbon quality control frequently comprises only sporadic activity tests performed on non-representative grab samples dipped from conve­niently accessed carbon storage bins. So, regenerated carbon quality may vary and (at times) be unacceptable for effective hydrometallurglcal circuit operation. To verify the efficacy of the regeneration process and assure accept­able adsorption and elution rates for Au(CN)2· and Ag(CN)2·, operators should systematically assess regenerated circuit carbon quality. This paper, then, suggests methods for effectively assessing circuit carbon quality, Including: carbon sampling procedures; standardized physical and chemical test methods; and criteria and general procedures for comparative adsorption rate (activity) testing. Also, a two tier quality control testing scheme is proposed, and techniques for presenting and interpreting test data are demonstrated.

Jan 1, 1992

By Anthony M. Opyrchal

This Bureau of Mines study assesses the economic significance of the Florida phosphate industry to selected counties in Florida, the State of Florida, and the Nation: it also includes a brief survey of the industry's international impact. Based on forecasts of Florida phosphate production in 1981, and using constant 1977 dollars. estimates are given for 1981 for regional and national output the value of this output, income, and employment created by the phosphate industry in Florida, Federal, Stale, and county tax revenues generated by the State's phosphate industry are also estimated for 1981. The concentrated impact of the phosphate industry on certain areas of Florida and on the State?s regional industries is examined using economic base analysis complimented by an industrial complex approach. The industry's impact at the Stare and national levels is examined through input- output analysis. In addition, an attempt to forecast for 1990 the effects of constraints on phosphate rock mining as a result of economic conditions and other factors is included as an appendix to the report. Also discussed is the phosphate industry's importance to the U.S. balance of trade: U.S. agricultural production. Including forward linkages; the U.S. sulfur industry; and the phosphate industry's importance to the production of fluorine and uranium by- products from fertilizer manufacturing.

Jan 1, 1981

By E. R. Buchanan, R. E. Reed-Hill, F. W. Caldwell

Poly crystalline zirconium tensile specimens containing a sizable fraction of grains unfavorably oriented for slip were deformed at 77°K to strains as high as 9 pct. The contributions of the various twinning modes to the observed strain were deter~nlned quantitatively using measured twin volume fractions and Schrnid orientation factors. The results indicate that at very small strains twinning can account for almost all of the observed strain. At higher strains slip becomes the dominant means of deformation. The most significant form of twinning was {1121}. PLASTIC deformation in polycrystalline aggregates is poorly understood even today. This is primarily because slip cannot be easily observed or studied in the interior of a metal. On the other hand, twinning can be discerned inside a specimen after deformation. Twinning studies can therefore often yield quantitative information about polycrystalline deformation not otherwise obtainable. This investigation uses the above aspect of twinning in determining the contributions of twinning to the strain during tensile deformation at a cryogenic temperature (77°K). Polycrystalline zirconium was used as the object of study. There are several reasons why this information should be of value. In contrast to many metals, both the strength and ductility of zirconium increase with a corresponding decrease in temperature. This may be related to the fact that twinning becomes more profuse and complex with decreasing temperature. Secondly, it has been discovered that certain room-temperature properties of zirconium can be greatly improved by about 1 pct prestrain at 77°K. These include an increase in tensile elongation in critical directions by over 50 pctl and a large mechanical hysteresis effect.2 Both effects are believed to be related to twins formed by prestraining: plastic twin-boundary movements accounting for the increased ductility, and anelastic twin-boundary movements for the internal friction. Thirdly, hexagonal metals which twin primarily on only the (1012) mode (such as beryllium, zinc, and magnesium), unlike zirconium, are very limited in ductility at cryogenic temperatures. Therefore, the significance of the various types of twinning in zirconium at cryogenic temperatures is of more than academic interest. Three twinning mechanism-s have beenobserved in quantity at WOK, {1012), {1121), and {1122). Each must be considered as a unique deformation mechanism because of their markedly different twinning shears and basically different angles between twinning and basal planes, as shown in Table I. It is therefore necessary to separately consider the role of each of these twins during plastic deformation at 77°K. Fortunately, each twin possesses unique morphological features which makes its identification possible on a properly prepared metallographic section. The use of the polarized microscope3 can also greatly aid in identification of the various forms of twins. EXPERIMENTAL PROCEDURE Arc-melted sponge zirconium plate, previously describedY4 was machined into 1/8 by 1 1/4 in. threaded-end, round tensile test specimens. These specimens were deformed to the desired strains in a liquid-nitrogen cryostat mounted in an Instron testing machine. The tensile axis was the transverse plate direction. This specimen direction resulted in large numbers of grains in orientations unfavorable for deformation by prism or basal slip. Deformed specimens were sectioned, mounted in epoxy cold-mount resin, ground on metallographic papers, electropolished, and anodized to provide surfaces sensitive to polarized light. Standard quantitative metallographic procedures5

Jan 1, 1965

Arizona E. P. MATHEWSON, Chairman W. V. DECAMP. First Vice-chairman H. W. ALDRICH, Second Vice-chairman E. D. GARDNER, Secretary-Treasurer, Care U. S. Bureau of Mines, Tucson, Ariz. F A. AYES, J. P. HODGSON W L DU MOULIN WILLIAM KOERNER Boston Meets first Monday each winter month GEORGE B WATERHOUSE, Chairman GEORGE A PACKARD, Vice-chairman F. LEROY FOSTER, Secretary-Treasurer Room 8-219, Mass. Inst. of Tech , Cambridge, Mass. F K MORRIS F S MULOCK

Jan 1, 1923

By S. Sener

In this investigation, the changes in the grindability of both ulexite and colemanite related with the different structural modifications created by the heat treatment were examined with respect to work index (Wi). The effects of the heat treatment temperature and time on grindability index were also investigated. It was observed that, heat treatment significantly affected on the grindability of ulexite. The work index of original ulexite was found 7.11 kWh/shton and decreased to 3.5 kWh/shton level within 200-480°C for 60 minutes. On the other hand, the work index of original colemanite was found as 6.48 kWh/shton and no appreciable change was observed when heated up to 320°C. Thermally assisted comminution can be used to improve the grindability characteristics of ulexite. Besides, the different behaviour of ulexite and colemanite under heat treatment can be used for their separation. The artificial mixture of ulexite and colemanite could be separated with over 90% recovery by utilizing their different grindability characteristics by thermal treatment, semi-autogeneous grinding and screening.

Jan 1, 1999

By L. Stein

A simplified radiochemical method has been developed for quantitatively analyzing; radon gas in underground uranium mines. In this method, a measured volume of air is drawn by a pump through a drying tube and a cartridge containing dioxygenyl hexafluoroantimonate reagent. Radon is captured as n nonvolatile product. After radioactive equilibrium has been established between radon and its short-lived daughters (approximately 4 hours), the gamma-emission of the cartridge is measured with a scintillation counter. The amount of radon is then calculated from the gamma-emission rate. The effect of cartridge geometry, reagent load, and air flow rate upon collection efficiency and counting efficiency is reported.

Jan 1, 1977

By B. N. Das, J. B. Darby, P. A. Beck, Y. Shimomura

A POWDER pattern for the (Cr, Mo, Co)R-phase annealed at 1200°C was reported in 1951.1 Through the courtesy of Prof. D. P. Shoemaker of Massachusetts Institute of Technology the authors became aware of inconsistencies of this pattern with that to be expected from the structure of the R-phase, as determined by Komura, Shoemaker, and Shoemaker.' In addition, Professor Shoemaker also noted that the powder pattern reported8 for the (Cr, Mo, Co)D-phase, annealed at 1300°C, agreed fairly well with that to be expected from the newly determined structure of the R-phase. In view of these findings, the previously reported powder patterns of the R-phase and of the D-phase were compared carefully. It was found that most lines in the two patterns (22 lines) were to a fair degree of accuracy related to each other by a single conversion ratio for the corresponding d spacings. The value of the conversion ratio was found to be 1.0058, so that the d spacings of the D-phase pattern previously reported were larger than the correspond- ing d spacings for the reported R-phase pattern by approximately that factor. The intensity relationships between corresponding lines in the two patterns were similar, as judged visually. The following exceptions were noted: Lines Nos. 2, 3, 19, 20, 21, 22, 23, 24 and 25 of the D-phase pattern,:' all designated weak or very weak, were missing in the apparently somewhat fainter R-phase pattern used.' Lines 1, 2, 3, 5, 15 and 34 (all weak or very weak), reported for the R-phase, were missing in the D-phase pattern, Table I. In view of these observations it seemed probable that the two patterns differed from each other mainly by a slight change in lattice parameters (with c/a remaining approximately constant), and that the pattern previously reported for the R-phase contained some weak extraneous lines, most likely to be attributed to impurities. In order to check the foregoing assumption, two specimens of an alloy containing 43 pct by weight of cobalt, 41 pct molybdenum, and 16 pct chromium, which was within the composition range of stability of both the D-phase at 1300°C and of the R-phase at 1200°C, were homogenized at 1200 and 1300°C, respectively, and quenched. X-ray diffraction patterns of the powders of these two specimens, obtained with CrK radiation, were compared carefully with each other and with the D-phase pattern previously

Jan 1, 1959