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By William S. Roberts

As part of the Bureau of Mines critical and strategic minerals program in Alaska, 34 high-purity chromian spinel samples were analyzed for trace and major element geochemistry and mineralogy. The samples were analyzed by X-ray diffraction, X-ray fluorescence, and chemical techniques. Systematic differences in chemistry are evident when samples collected from the Chugach Mountains and their related extension are compared with chromian spinel samples collected from interior Alaska. Compared with the Chugach samples, the interior Alaska samples have higher average amounts of A1203, Fe203, Ti02, and NiO, have lower average amounts of FeO and Cr203, and exhibit greater dispersion in values. Considerable mineralogical variability of chromian spinel exists between and within individual Alaskan chromite-bearing ultramafic complexes. Of 34 samples analyzed, 25 samples are magnesiochromite, 5 are chromite, 3 are spinel, and 1 is hercynite. As a group the interior Alaska samples have a smaller average unit cell dimension than the Chugach group of samples. The chemical and mineralogical differences between the two groups of samples can be attributed to different genetic histories and may have implications for locating chromian spinel deposits amenable to standard beneficiating techniques.

Jan 1, 1985

By L. G. Marshall

This report presents a cross section of the sand and gravel operations in the Minneapolis-St. Paul area. The study covers individual operations, economic problems peculiar to the industry, glacial geology of the area and its effect upon the grades and types of products, and past, present, and future trends of the expanding population and its effect upon the industry.

Jan 1, 1963

By L. G. Marshall

This report presents a cross section of the sand and gravel operations in the Minneapolis-St. Paul area. The study covers individual operations, economic problems peculiar to the industry, glacial geology of the area and its effect upon the grades and types of products, and past, present, and future trends of the expanding population and its effect upon the industry.

Jan 1, 1963

By John H. Schilling

The Gabbs magnesite-brucite deposit is unique in size and is one of two magnesite deposits being exploited in the United States. It is near the town of Gabbs, which is one hundred miles southeast of Reno, in west-central Nevada. The brucite was discovered in 1927; the magnesite was found while exploring the brucite. During World War II, more than 80,000 tons of magnesium metal was produced from about 900,000 tons of magnesite ore mined from these deposits. An additional 5,000,000 tons of magnesite and 1,000,000 tons of brucite have been produced for use in making magnesia refractories and chemicals. Basic Inc., presently the only producer, mines 1.5 ± 0.25 million tons of ore and waste annually using high-selective open-pit rriethods; the ore is up-graded, calcined, and processed into a variety of products. Known reserves of highgrade (less than 5 per cent CaO) magnesite ore total more than 25,000,000 tons, and there are larger tonnages of lower-grade material; brucite reserves are small. The magnesite and brucite are in generally west-dipping dolomite of the upper member of the late Triassic Luning Formation, in the over-riding plate of the Paradise thrust fault. A great variety of dikes and a stock of Cretaceous granodiorite intrude the Luning Formation in the vicinity of the magnesite-brucite deposit. The magnesite bodies are scattered over an area of about a square mile around a prong of granodiorite which extends north from the stock. The brucite is mainly in two bodies in contact with the prong of granodiorite; at the surface and along deeper cracks the brucite has weathered to hydromagnesite and artinite. In the area of magnesite-brucite mineralization, much of the dark, fine-grained, schistose, regionally-metamorphosed dolomite of the Luning Formation has been marmorized to a lighter-colored, coarser-grained, massive dolomite that is intergrown in varying proportions with the magnesite. The magnesite and marmorized dolomite can not be distinguished visually. In addition to the two varieties of dolomite, the gangue in the magnesite and brucite bodies mainly is the various varieties of dike rock, serpentine and a variety of other "contact" minerals, and "post-ore" dolomite and calcite. The magnesite ( and recrystallized dolomite) is believed to have formed by the hydrothermal replacement of the regionally metamorphosed sedimentary dolomite; alternatively it has been suggested that the magnesite is sedimentarv and formed contemporaneously with the dolomite in an embayment of the Triassic sea. Because all the igneous rocks exposed in the immediate vicinity of the magnesite deposits appear to be younger than the magnesite, the ore-forming solutions are thought to be related to a somewhat older granite which crops out elsewhere in the area. The brucite is the result of contact-metasomatic replacement of magnesite during the emplacement of the granodiorite stock.

Jan 1, 1968

By Lowell Stroud

Since 1929, the Helium Activity of the Bureau of Mines has operated a helium-extraction plant at Amarillo, Tex. The natural gas that supplies this plant is obtained from the Cliffside geologic structure 12 miles to the northwest and over the years, has become known simply as "Cliffside gas," There is need for published data on the low-temperature phase equilibria of helium-bearing natural gases. To date, little information has been published on the equilibrium phase compositions, solution of helium in condensed natural gas, condensation characteristics, or equilibrium vaporization coefficients for methane, nitrogen, and helium in helium-containing systems. A windowed phase equilibrium apparatus (8)6 was used to obtain 105 equilibrium samples, representing 35 experimental conditions of condensed Cliffside gas at pressures of 100, 200, 300, 400, and 500 p.s.i.a. and temperatures from 0° to -270° F. Data on equilibrium vapor-liquid composition for Cliffside gas are presented in both tabular and graphic form and are discussed in detail to show their relationship to certain criteria that must be met to effect an efficient separation of helium from natural gas by means of low-temperature processes. Facts about condensation characteristics and solution of helium in the liquid phases are included, The important relationship of these two factors in decreasing the percentage of total helium lost by solution in the liquid phase is discussed.

Jan 1, 1961

R. W. Raymond, New York City: As was announced in the Secretary's note, appended to the pamphlet edition of Dr. Ledoux's paper, I have undertaken to superintend the preparation of the samples required by his plan, and the ollation for publication of the results reported. Promises of cordial co-operation hare been received already from a number of leading assayers;? and it is to he expected that the data thus collected, and the discussion to be based upon them, will shed much light upon the important question raised in this paper. Although a detailed discussion of methods on the present occasion might be deemed premature, I am sure that suggestions on the subject from members engaged in assaying would be timely and valuable as a preliminary to later and more detailed criticism. Herbert G. Torrey (U. S. Assay Office), New York City : I may say in relation to the losses in the furnace that I have made a number of experiments, and on my little blank form years ago I put down a place for the losses in the cupel. It met with a good deal of opposition among the smelters, but I claimed that it was my duty to give the full amount of the gold and silver present, and that it

Jan 1, 1895

By Laura Pires Ribeiro Martins

Para a produção de peças e componentes automobilísticos, a utilização de ensaios não destrutivos é de grande importância, tanto para a detecção de defeitos como para a estimativa de propriedades físicas e mecânicas. Este estudo tem como objetivo avaliar dois métodos de ensaios não destrutivos (frequência de ressonância e ultrassom) através da determinação do módulo de elasticidade e do amortecimento de vibrações, em ferros fundidos vermiculares de classe FV 450. Estas técnicas também foram avaliadas para identificar a presença de microporosidades de contração na solidificação. Verificou-se que estas metodologias permitem estimar valores de módulo de elasticidade com bastante precisão, superior à obtida com ensaios de tração. Comprovou-se ainda que a capacidade de amortecimento de vibrações, avaliada pela taxa de atenuação da oscilação, é sensível à presença de interfaces na microestrutura do material, bem como à presença de pequenas porosidades.

Aug 16, 2017

By A. Hultgren, G. Phragmén

Page Outline of Progress of Knowledge and Theories about Gas Evolution in Steel Ingots. and Its Influence on Crystallization and Segregation................ 134 Object of Present Investigation........................................... 148 Theoretical Discussion of Process of Solidification........................... 149 Gas Given Off from Rimming Steel during Solidification................... 149 Equilibrium Diagram of the Iron-carbon-oxygen Alloys................... 151 Solidification of Pure Iron-carbon-oxygen Alloys.......................... 157 Solidification when Carbon Monoxide Is Given Off at Constant Pressure... 157 Solidification when Gas Evolution Is Suppressed....................... 158 Schematic Application on Solidification of Rimming-steel Ingots.......... 159 Influence of Manganese, Sulphur and Phosphorus......................... 160 Experimental work..................................................... 162 Liquid Steel and the Mold Gas......................................... 162 Ingots Investigated and Methods Used.................................. 165 Ingot structure....................................................... 174 Structure of Rim Zone.............................................. 174 Structure of Core................................................... 181 Structures Obtained under Special Conditions of Freezing................ 182 Distribution of Metalloids............................................. 187 Other Observations Made............................................. 192 General Discussion of Solidification Process................................. 195 Condition of Liquid Steel before Casting................................. 195 Rimming Period...................................................... 202 Composition of Rim Zone............................................. 225 Freezing after Top Is Closed........................................... 228 Slag Inclusions and Ingot Scum........................................ 234 Reaction between Gas in Blowholes and Surrounding Solid Steel during Cooling 235 Summary.............................................................. 237 Appendix—Preparation and Etching of Ingot Sections....................... 238 References............................................................. 239 In 1934, Jernkontoret (The Swedish Ironmasters' Association) appointed a committee for the study of the structure of rimming-steel ingots and the various phenomena associated with their solidification. The members of the committee, including those who have joined it later, have been: I. Bohm, B. D. Enlund, B. Kalling, M. Tigerschiöld, S. Wohlfahrt and the authors. The present paper‡ is a somewhat

Jan 1, 1939

By G. Phragmén, A. Hultgren

Page Outline of Progress of Knowledge and Theories about Gas Evolution in Steel Ingots. and Its Influence on Crystallization and Segregation................ 134 Object of Present Investigation........................................... 148 Theoretical Discussion of Process of Solidification........................... 149 Gas Given Off from Rimming Steel during Solidification................... 149 Equilibrium Diagram of the Iron-carbon-oxygen Alloys................... 151 Solidification of Pure Iron-carbon-oxygen Alloys.......................... 157 Solidification when Carbon Monoxide Is Given Off at Constant Pressure... 157 Solidification when Gas Evolution Is Suppressed....................... 158 Schematic Application on Solidification of Rimming-steel Ingots.......... 159 Influence of Manganese, Sulphur and Phosphorus......................... 160 Experimental work..................................................... 162 Liquid Steel and the Mold Gas......................................... 162 Ingots Investigated and Methods Used.................................. 165 Ingot structure....................................................... 174 Structure of Rim Zone.............................................. 174 Structure of Core................................................... 181 Structures Obtained under Special Conditions of Freezing................ 182 Distribution of Metalloids............................................. 187 Other Observations Made............................................. 192 General Discussion of Solidification Process................................. 195 Condition of Liquid Steel before Casting................................. 195 Rimming Period...................................................... 202 Composition of Rim Zone............................................. 225 Freezing after Top Is Closed........................................... 228 Slag Inclusions and Ingot Scum........................................ 234 Reaction between Gas in Blowholes and Surrounding Solid Steel during Cooling 235 Summary.............................................................. 237 Appendix—Preparation and Etching of Ingot Sections....................... 238 References............................................................. 239 In 1934, Jernkontoret (The Swedish Ironmasters' Association) appointed a committee for the study of the structure of rimming-steel ingots and the various phenomena associated with their solidification. The members of the committee, including those who have joined it later, have been: I. Bohm, B. D. Enlund, B. Kalling, M. Tigerschiöld, S. Wohlfahrt and the authors. The present paper‡ is a somewhat

Jan 1, 1939

By R. Lindsay Mundell

In the first half of 1990, lessening of cold war tensions was welcome. But Iraq's invasion of Kuwait in August led to the Persian Gulf War in January and February 1991. The subsequent oil shock contributed to a dampening of the U.S. economy, and the U.S. gross national product rose only 0.9 % to $5,463 billion (U.S. billion = 109). The buildup of military forces in the Persian Gulf area focused greater attention not only on petroleum but also on other strategic materials. The U.S. Department of Defense continued to review stockpile goals and upgrade several mineral materials. In addition, the U.S. Bureau of Mines continued to maintain the standby Emergency Minerals Administration. After the Defense Production Act, which authorizes priorities, allocations, and supply expansion, lapsed on October 20, 1990, the Selective Service Act of 1967 became the authority to ensure that orders of the Armed Forces and defense atomic energy programs were given priority treatment.

Jan 1, 1993

By William T. Boyd

Foreign mining publications describing successful hydraulic mining installations, and successful domestic hydraulic mining in a gilsonite bed, have prompted the Federal Bureau of Mines to conduct a literature survey of foreign publications to determine if the hydraulic mining method can be applied to domestic coal mining. Most foreign publications do not give detailed data about the water pressures, water capacities, and production and manpower requirements for successful hydraulic mining, However, they do provide enough general data on mining conditions, manpower, and equipment used to show that conditions in many bituminous coal deposits in the United States may be favorable for economical coal extraction, using high-pressure water jets. Therefore, the Bureau proposes to conduct a field investigation to determine the most appropriate natural conditions, water pressures, and equipment for successful hydraulic mining of coal beds in the United States with variable dip, thickness, and hardness. In the past, technical personnel reviewing foreign mining reports assumed that a steeply pitching coal bed was necessary for successful hydraulic mining. Although the structure of the coal bed may be a factor in gaining assistance from overburden pressures or help in an integrated hydraulic mining and transportation system, the coal is broken mainly by the action of high-pressure, water-penetrating cracks, fissures, or cleats; therefore, the slope of the coal bed is not necessarily a determining factor in hydraulic mining.

Jan 1, 1959

By Sean Dessureault

Dentro de los procesos de la operación minera, se requiere conocer las etapas que describen el planemiento y la extracción hasta la entrega final del mineral. En ese sentido, el presente texto se enfoca en el control del blending de una de las minas de carbón más grandes que se encuentra en el estado de Wyoming, Estados Unidos.

Jan 1, 2012

By Henry H. Ginsberg

The effectiveness of 0.01 pct. molybdenum, as ammonium molybdate impregnated on coal, on the hydrogenation of a high-volatile bituminous C coal at 8,000 p.s.i.g. and 460° to 480° C. has been studied in a pilot plant by the Federal Bureau of Mines. Under these conditions, the Bureau obtained 98 to 99 pct. conversion5/ of coal to liquids and gases at throughputs of 29 to 101 lb. of m.a.f. coal per cubic foot of reaction space per hour. At 460° C. the indicated yield of oil ranged from 63 pct. (based on m.a.f. coal) at a throughput of 35 lb./c.f.h. (pounds per cubic foot per hour) to 68.5 pct. at a throughput of 58 lb./c.f.h., and the yield of gaseous hydro-carbons ranged from 25.5 to 19 pct. at the same throughputs. The maximum measured yield of oil boiling under 325° C. was 47 pct.

Jan 1, 1960

By Verônica Scarpini Candido

O uso cada vez mais frequente do poli metacrilato de metila (PMMA), muitas vezes em substituição ao vidro temperado, se deve a sua alta rigidez, praticidade, leveza e transparência. No entanto, as normas de fabricação atuais na indústria de polímeros recomendam testes específicos nesses materiais. O presente estudo tem o objetivo de testar mecanicamente as propriedades do material Polimetacrilato de Metila (PMMA) em condições que simulem um ambiente muito mais agressivo do que o usual. Para tanto foram realizados testes de espectroscopia na região do infravermelho (FTIR), análise termogravimétrica (TGA), testes de tração e impacto Izod, e análise por Microscopia Eletrônica de Varredura (MEV). Os resultados revelaram que o Polimetacrilato de metila (PMMA) manteve suas propriedades mecânicas em tração até a temperatura de 105°C. No que se refere à resistência ao impacto, a temperatura influenciou negativamente no desempenho desse polímero.

Oct 30, 2017

By C. P. Broadbent

The process metallurgy of many nickel laterite smelting operations is controlled largely by the physical chemistry of the slag system. Consequently, accurate phase diagram information and physicochemical property data are essential to interpret and predict the behaviour and optimisation of the overall process. The system (SiO2 - MgO - FeO) first described by Bowen et al. between 1914 and 1935 and the system (SiO2 - MgO - FeO - Fe2O3) determined by Muan and Osborne in 1956 are of particular relevance to the study of nickel laterite smelting slags as these systems form a reasonable approximation of many industrial slags. This paper will review the literature for these (and other relevant) phase systems. In addition data available from the ternary and (quasi)ternary phase diagrams will be compared with data obtained from industrial slags. The physico-chemical properties under consideration will include; melting and crystallisation behaviour (solidus and liquidus temperatures), viscosity - temperature relationships, heat flux considerations, electrical conductivity, surface and interfacial tension.

Jan 1, 1993

By R. W. Geehan

The Bureau of Mines has been investigating deposits of critical and essential minerals in the United States since 1939. Bureau engineers made a preliminary examination of the Morefield mine early in 1943 and recommended investigation by trenching and diamond drilling, The Bureau of Mines conducted work from August to December of 1943, which indicated that the Morefield mine was a favorable location for an experimental mining program. The Bureau of Mines carried on such a program from September 1947 to March 1949. The property investigated is 30 miles southwest of Richmond in Amelia County, Va. (fig. 1). During World War II mica and beryl were shipped from the Morefield mine, but after the high prices and premiums paid during the war years were not available the mine was closed.

Jan 1, 1953

By D. G. Willard

The U.S. Department of Interior, Bureau of Mines has evaluated the potential resource and annual availability of cobalt from 27 deposits or districts in 11 market-economy countries. More than 95 pct of primary cobalt production from market-economy countries, mainly byproduct output from copper and nickel operations, was analyzed. Approximately 1,200,000 mt of cobalt is potentially recoverable at the demonstrated resource level. Very large additional resources exist, especially in laterite deposits, but are at the inferred level. The producing operations evaluated in this study are expected to produce about 19,000 mt of cobalt in 1989, significantly less than the available capacity of about 31,000 mt. More than 14,000 mt per year of cobalt is produced from copper-cobalt deposits in Zaire and Zambia, of which 11,000 mt can be produced at a copper price of $O.60jlb or less with a O-pct discounted cash-flow rate of return (DCFROR). Approximately 4,400 mt of cobalt is produced annually from nickel-cobalt deposits in six countries, of which about 1,800 mt (in Canada and Brazil) could be produced at a nickel price of $1.50jlb or less at a D-pct DCFROR. Approximately 200 mt per year of cobalt is produced from a cobalt mine in Morocco. Most of the evaluated nonproducing operations and prospects that could potentially produce cobalt as a principal product or byproduct would require a total cost (including a 15 pct-DCFROR) significantly exceeding January, 1989 market prices of the principal commodities. Principal-commodity dependence, transportation routes, cobalt toxicity, and other issues that could affect the availability of cobalt are addressed herein.

Jan 1, 1991

By Cleiton Rodrigues de Vasconcelos, Elizeth Oliveira Alves, Kleber Gonçalves Bezerra Alves

Em virtude da periculosidade do Pó de aciaria (PAE), práticas alternativas, como a reinserção do resíduo no processo produtivo, ou sua incorporação em outros materiais fizeram com que a reciclagem tenha se tornado uma via para este subproduto. O presente trabalho tem como objetivo identificar as áreas de desenvolvimento tecnológico de utilização do PAE, avaliar a potencialidade de reaproveitamento e reciclagem do resíduo oriundo do processo de produção do aço carbono, comparando as características obtidas do PAE analisado com os requisitos indicados através da análise de patentes. O PAE produzido no estado de Pernambuco foi caracterizado pelas técnicas de Fluorescência de raios X (FRX), separação granulométrica via peneiramento, distribuição do tamanho de partículas, Difração de raios X (DRX), Microscopia eletrônica de varredura (MEV) e Espectroscopia por energia dispersiva (EDS). A prospecção tecnológica foi realizada nas bases de patentes europeia EPO e na base nacional de patentes nacional do INPI. As análises realizadas mostraram que o material apresentou aproximadamente 28,5% de suas partículas com granulometria inferior a 53μm, composto em sua maioria por ferro e zinco presentes na forma de óxidos, organizados nas fases franklinita, zincita e magnetita. A baixa granulometria e composição química possibilitam a sua aplicação no campo dos materiais cerâmicos, bem como sua reinserção no processo de fabricação. O resíduo estudado apresentou características similares com os demais resíduos observados nas patentes.

Mar 1, 2019

By Foluke Salgado de Assis

Este trabalho visa apresentar alguns resultados obtidos através de ensaios balísticos realizados em sistemas de blindagem multicamada. Seguindo as especificações da norma americana NIJ 0101.06, foram realizados ensaios utilizando munição de calibre 7,62x 51 mm, que possui velocidade acima de 800 m/s. A blindagem multicamada utilizada possui como camada frontal uma pastilha hexagonal cerâmica (alumina dopada com 4% de nióbia), segunda camada de compósito de matriz poliéster reforçada com tecido de juta e como terceira camada uma placa de alumino 5052 H34. A utilização de compósitos poliméricos reforçados com fibras naturais em substituição às fibras de aramida é de grande interesse, pois além de desempenharem a mesma função no sistema de blindagem, possuem um valor de mercado bem menor. Com os resultados obtidos do ensaio balístico, os valores foram associados com o seu comportamento dinâmico utilizando o método do casamento de impedâncias.

Aug 17, 2017

By C. Hendricks

This paper is based upon field studies conducted in a western Canadian open pit coal mine. This work has involved the adaptation of microprocessor-based instrumentation to monitor various operating parameters on-board blasthole drills and mining shovels. A review of instrumentation and monitoring methodology will first be presented. Based upon experience from field-based studies, the paper will subsequently focus on the application of monitoring technology within the framework of an integrated Equipment Monitoring System. Such a system will permit the real-time performance evaluation of key equipment involved in surface mille production.

Jan 1, 1991