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By NEFE NONE

Possible New U.S. Half-Dollar. - Tile George Washington Commemorative Coin Act, H.R. 3133, was introduced in the House and approved by the House Banking Committee. It would allow the minting of at least 10 million commemorative silver half-dollars the size of the same coin produced before 1965. A companion bill, S. 1228, was introduced in the Senate. Taxes and the U.S. Minerals Industry. - The General Accounting Office completed a report to Congress on "Assessing the Impact of Federal and State Taxes On the Domestic Minerals Industry." the study presents a quantitative method to assess the effect of taxes on profitability, and suggests ways to use taxes or tax credits to help marginal mine operations and possibly to increase mineral production, Limited copies of the 139-page report are available free of charge from U.S. General Accounting Office, Documents Handling & Information Sevices Facility, P.O. Box 6015 Gaithersburg, Md. 20760.

Jan 1, 1981

Anaconda Aluminum Co. began production from a new 60,000-ton-per-year potline at Sebree, KY, which brings the total capacity of the plant to 180,000 tons per year. A strike by workers at Alcan Aluminium Corp. primary aluminum smelters at Arvida, Que., Isle Maligne, Que., and Beauharnois, Que. shut down the plants and the company announced force majeure on part of its ingot supply commitments. Kaiser Aluminum and Chemical Corp. announced plans to increase its price for primary aluminum from 60.0 cents per pound to 63.0 cents per pound effective July 1.

Jan 1, 1979

By H. W. Gillett, E. L. Mack

Prior to 1911 the literature on melting brass by electricity consisted entirely-save for some suggestions made in patent literature but not actually worked out-of a few observations by farseeing men ' on the theoretical advantages of melting brass and other nonferrous alloys in electric furnaces. Roeber was the first to see and clearly state the possible advantages of the electric furnace in brass melting. The same factors tha.t make it desirable to manufacture special steels in the electric furnace rather than in crucibles, he declared, apply to brass as well. He pointed out the possibility of using larger melting units, of eliminating crucible cost, of readily controlling the purity of the product. and of nearly eliminating the loss of zinc. "The replacement of the • old crucible process is sure to come," he said; "perhaps it will come in two years, but it will, necessarily, in ten years .... The inevitable advance along this industrial line will have great influence in the metal world and will also provide, in large cities, a new kind of load for the central station." The years 1905 to 1910 may be termed the purely theoretical period of the development of the electric brass furnace, though the Conley furnace was tried out e:xperimenta.lly about 1910 and a few heats were made in an induction furnace. 2 In December, 1911, the American Chemical Society held a symposium on mineral wastes, at which Bassett s discussed the zinc· losses that attend making brass in fuel-fired furnaces.

Jan 1, 1922

By Jorge Nelson Rivera Guillén

"La tierra es una unidad de un complejo astral que se observa desde la antigüedad en sus aspectos exteriores y su dependencia del sistema solar. En ese sentido, el presente texto señala la génesis y evolución de los minerales comprendido en la tierra a través de cuatro libros denominados ""Los misterios del planeta tierra"", donde se mencionan los aspectos tectónicos preliminares y preparatorios para la disgregación de la Pangea Nueva, cuya “lenta explosión” ocasionó la separación de las placas tectónicasy la acción de fuerzas distensionales que actuaron sobre los fragmentos que generan desequilibrios barotérmicosinternos y la formación de zonas magmáticas y metalizaciones."

May 1, 2015

By BUREAU OF MINES

Mercury has been used by mankind since prehistoric times. It has been, and is now, widely used in industry and medicine and has unique properties which make direct substitution difficult or impossible. At present its prin- cipal uses are for electrical apparatus, control instruments, electrolytic soda preparation, mildew-proofing paints, pesticides, and medical and dental preparations. Deposits of mercury are less common than those of other base and precious metals, but some of the deposits are very large and have been ample to meet the world's past demands. The price of mercury has had many sharp fluctua- tions, but in general, the limited number of producers has resulted in a more stable price structure than that of many other commodities. The United States has been one of the main producers of mercury, and from 1850 to 1961 produced 3,247,704 flasks. Yearly production since World War II has varied from 4,535 to 38,067 flasks. An estimate of domestic resources of mercury producible at various price ranges was prepared for each mercury mine by combining specific knowledge of mercury mineralization with estimates of potential, based on geologic informa- tion and past production history. The sum of the individual estimates for each price range is shown in a table. A parallel estimate of nationwide production potential was made from a study of past price and production relationships. These were analyzed by plotting yearly production figures against the previous year's price, expressed in dollars of constant purchasing power. An equation was fitted to the data by mathematical means and was used to extend the curve into areas of higher than historic prices. Potential production rates at various price levels were taken from this graph. The estimated yearly production rates were used to make an estimate of total potential based on the premise that produc- tion rates and reserves have a proportionate relationship.

Jul 1, 1964

New GSP Trade Status Approved.--President Carter, by Executive Order effective March 30, has approved Generalized System of Preference treatment for imports of nonferrous metal products and other imports from Ecuador, Indonesia, Zimbabwe, Uganda, and Venezuela. As of May 2, Afghanistan and Ethiopia will be taken off GSP status. Under the Generalized System of Preferences, certain imports from developing countries are provided duty-free treatment. A country can lose its GSP status if its shipments of the product exceed $41.9 million or more than 50% of total U.S. imports during the preceding year. However, the President can waive the 50% rule in cases where total U.S. imports of an item in 1979 were less than $1 million. Certain nonferrous imports from Mexico, Peru, Chile, and Zambia are already covered by GSP. Hearings April 10 on International Tin Agreement.--The Fifth International Tin Agreement of which the United States is a signatory, which entered into force on July 1, 1976, will expire on June 30, 1981. A negotiating conference for a Sixth International Tin Agreement will be held under auspices of the United Nations at Geneva from April 14 to May 16, 1980.

Jan 1, 1980

By Belisario Pérez

Con el objetivo de lograr cero accidentes en las empresas minero-metalúrgicas de la división minera Breca, se fortaleció la gestión de incidentes mediante la incorporación de los eventos de alto potencial (EAP). En el periodo del 2012-2018, en gran medida gracias a la gestión de los EAP, se logró una reducción del 91% del índice de frecuencia de accidentes incapacitantes y del 100% en el número de accidentes fatales. El presente trabajo detalla dicho modelo de gestión, que puede servir para mejorar el desempeño de seguridad de otras empresas minero-metalúrgicas en el país, contribuir a la reducción de accidentes en el sector y lograr así el objetivo de cero accidentes.

Sep 20, 2019

By K. K. Kelley

This work is both a revision and an elaboration of Bureau of Mines Bulletin 371, which was published in 1934 and included data available to October 1933. During the intervening years, a large number of new experimental, high-temperature, heat-content data have become available through continuous, systematic efforts of the Pacific Experiment Station of the Bureau of Mines and the Laboratory for Inorganic and Physical Chemistry of the University of Groningen (Netherlands), coupled with various individual investigations at many institutions. In addition, calculations from spectroscopic and molecular constant data have been extended and applied to a wide variety of gaseous substances. This bulletin purposes to collect and correlate all available high-temperature heat-content and specific-heat data for inorganic sub-stances and to formulate tables and algebraic expressions for their representation. It is hoped in this manner to remove some of the tedium of thermodynamic calculations for industrial metallurgical research workers and engineers who often have available only an inadequate library in this field. It is expected also that this bulletin will have value to those teaching courses in metallurgical and chemical thermodynamics.

Jan 1, 1949

By Camila Cabrera, Francisca Rivero

El objetivo de este trabajo es proponer un modelo integrado de gestión de cierre de faena minera que permita la transición económica, social, cultural y ambiental de las y los habitantes del territorio en un escenario post-minería. Para ello, se realizó un benchmarking de experiencias de cierre y un análisis comparativo de regulaciones nacionales de Perú y Chile, además de una revisión de estándares internacionales. Asimismo, se elaboró un instrumento con el fin de identificar la información crítica para el diseño de un Plan Integral de Cierre, y una herramienta para evaluar los impactos sociales y oportunidades del cierre de faena.

Sep 29, 2023

By Patricio Campos

Durante los diez últimos años, la perforación hidráulica ha desplazado al sistema neumático en aplicaciones mineras y obras civiles. En ese sentido, el presente texto describe las ventajas e inconvenientes de este sistema hidráulico como alternativa futura en el campo de la perforación. La aplicación de esta tecnología aumentó la productividad en la perforación de roca y disminuyó a un costo menor de operación que la de perforadora neumática. De forma que se la considerará como proceso obligatorio en breve plazo, al tiempo que mejora el ambiente de trabajo del personal.

May 1, 1982

By Terry R. Guilinger

A minitest of the new potassium chloride-potassium carbonate two-stage in situ uranium leach process has been carried out at the Intercontinental Energy Corporation (IEC) Zamzow project site in South Texas. Substantial quantities of high concentration uranium were produced indicating the viability of the leach solution. The test results yield information regarding the reservoir dispersivity, the average cation-exchange capacity of the formation, and the distribution coefficients describing carion-exchange reactions. The test a1 so indicates permeability anisotropy and the existence of disturbed flow fields. The research was partially funded by the U.S. Bureau of Mines.

Jan 1, 1984

By C. B. Manula

Bituminous coal mining in the United States is currently experiencing a period of rapid growth which began in the early 1960's. Future demands are conservatively predicted to rise to 700 million tons by 1980 and to anywhere between 1 to 3 billion tons by the turn of the century. This means a continuous expansion of coal production by a factor of at least two can be expected before the end of the century. Over the last few years, production from underground mining has decreased; yet it is about 50% of the total coal output. In the absence of any discovery of near surface coal deposits, and even after conceding that some deeper deposits can be surface mined with changes in technology it can be reasonably assumed that coal production from underground will continue to play an important part in solving the energy crisis.

Jan 1, 1975

By Henry Branes

Para maximizar el retorno de la inversión se aplica la economía de escala pero no se consideran el riesgo financiero al aumentar la escala del proyecto. Las curvas de recuperación metalúrgica vs ley de minera no son lineales. Esto implica elegir un punto óptimo, donde los rendimientos decrecientes de la minería selectiva no justifican el aumento del costo de minado y la reducción de la tasa de alimentación a planta. El artículo analiza las variables más significativas y propone una metodología para definir la capacidad de planta óptima para obtener el máximo rendimiento de la inversión basado en la sensibilidad de una serie de escenarios de planes de minado.

Sep 1, 2017

By Mijail Denisov

El presente trabajo señala las características de la composición geológica de los pequeños yacimientos de los metales no ferrosos. Para ello señala los puntos principales de la apreciación de los pequeños yacimientos desde la eficiencia económica. De otro lado, la parte proporcional correspondiente a los pequeños yacimientos de los metales no ferrosos en las reservas y extracción de minerales, disminuye sistemáticamente. Asimismo, gran número de pequeños yacimientos predetermina la posibilidad de realizar extensos trabajos de extracción y obtener minerales en volumen considerable.

Jul 1, 1981

By N. B. Aughenbaugh

This report summarizes the results of an investigation into the causes of coal mine roof instability caused by the environmental characteristics of the air ventilated through a mine. The field studies, which were mostly in the Illinois Coal Basin, concentrated on collecting data of surface weather conditions, mine air characteristics (relative humidity and temperature), roof material types, roof movements, and characteristics of roof deterioration. The field studies revealed seasonal changes in weather are reflected in the mine air. The intake air undergoes rapid tempering along its course as it interacts with the ambient mine conditions. There are seasonal moisture interchanges between the mine rock and air, and a mine will lose more water than it gains on a yearly basis. The field studies also established that when the roof rock is shaley, seasonal changes in the humidity will cause roof deterioration because of the detrimental action of moisture on the shale. Roof falls were inventoried and classified by geometry. In the laboratory investigations, physical tests proved unreliable for evaluating shales for roof stability. The Franklin slake test lacks the sensitivity needed to differentiate shale durability for roof stability. A relative humidity test that reveals the sensitivity of a shaley rock to moisture change was devised. Environemntal chamber studies showed that neither temperature nor barometric pressure have a direct influence on shale durability. Photoelastic studies showed that the rate and depth of moisture absorption into a shale is controlled by bedding planes, fractures, and holes interrupting the exposed surface.

Jan 1, 1976

By J. C. Johnson, W. G. Pariseau, D. F. Scott, F. M. Jenkins

In situ stresses are important input data for the design of safe, stable stope layouts and extraction sequences. However, it is commonly assumed that normal and shear stress gradients in a stress field are negligible and, consequently, that stresses are uniform throughout the region of analysis. To evaluate these assumptions and to provide input data for an analysis of a shaft pillar mining plan, in situ stresses were measured at the Homestake Mine, Lead, SD, using overcoring on hollow inclusion cells and borehole deformation gauges. These measurements were used with conventional least squares, best fit data reduction schemes. The results showed that normal stresses within the shaft pillar were less than, but comparable to, those estimated from finite-element modeling. Shear stresses were an order of magnitude less than normal stresses and varied considerably from site to site. Possible causes of this variability include effects of scale, elastic moduli, anisotropy, and axial strain. Because of the variability, it is not possible to determine the magnitude of horizontal stress gradients.

Jan 1, 1993

By Jack E. Brockway

As tunnel boring machine technology has expanded, so has its range of application. Tunneling machines (TBM's) are tackling tasks today that fifteen years ago were considered "inappropriate". A case in point is incline/decline TBM boring. An incline or decline bore presents peculiar design considerations that differentiate it from a horizontal bore. This paper reviews those design considerations as they apply to TBM's, backup, muck handling and other tunneling subsystems. In addition, several abbreviated case studies are presented. By the review of real life tunneling techniques as well as design considerations, the "appropriateness" of TBM incline/ decline boring today becomes apparent. INCLINE Introduction In contemplating the impact of incline versus horizontal tunnel boring system design, the obvious consideration is gravity. Up-hill boring can be quite different than horizontal boring. Muck, water and machine weight all tend to slide down the incline. In addition, hydraulic and lubrication systems if unaltered, will find their fluids pooled in the lower corners contentedly ignoring such higher elevation items as gears and bearings. In order to address this inherent gravity problem, a review of

Jan 1, 1983

By Meylin Terrel-Gutierrez

El presente texto muestra un modelo cuasianalítico para predecir la SD (Sechi) en cuerpos de agua claros y turbios. El enfoque está basado en el la relación inversamente lineal entre la SD y las concentraciones de OAS, donde la última ha sido reemplazada por su banda de reflectancia correspondiente o sus combinaciones propuestas por estudios previos de acuerdo con el tipo de cuerpo de agua.

Jan 1, 2014

Who Macraes Mining Company Limited is can be summed up by the following statements: +         We have been New Zealand's largest gold producer for seven years +         We have one of the lowest market capitalisation per reserve ounce of the gold producers in the  Australian Gold Index +         We have a resource finding cost of less than NZ$l0 per ounce +         We have a large land bank with proven reserves +         We have an Operating Cash Margin of approximately NZ$200 per ounce +         We have reduced our Dry Milled Tonne Cost by 34% since 1992   Our Mission is to continually grow our gold business, through maximising cashflow and focusing on our value drivers being: +         Increasing reserves +         Increasing cash operating margins +         Increasing production   The real challenge is the reduction of operating costs and the optimisation of revenue, particularly in the current gold price environment.   The Company has as at 31 December 1996 total mineral resources of 6.1 million ounces and reserves of 3.4 million ounces. This together with our current cash position of approximately NZ$15 million and strong hedging book of approximately 800,000 ounces places the Company on a sound financial footing whilst positioning itself to aggressively pursue its growth strategy when gold price and market conditions improve.

Jan 1, 1997

By José Luis Quijahuamán

El presente trabajo señala el cambio de proceso metalúrgico de flotación a cianuración CIL para el tratamiento de mineral del yacimiento Chipmo en la Planta de Procesos de Orcopampa, donde se trata principalmente minerales de oro con bajo contenido de plata, así como las ventajas de su aplicación. Los beneficios que ha generado este nuevo proceso involucran los aspectos económicos, sociales y ambientales respectivamente. El primero, refiere un mejor costo beneficio, la mayor recuperación de oro, la comercialización de dore como producto final del proceso y el menor número de personal en las operaciones debido a la simplificación del proceso; el segundo, señala el cambio a un mejor clima organizacional en la empresa y la irrigación de terrenos eriazos, beneficiando a pobladores de las comunidades cercanas. Finalmente, el tercero, describe la reducción de aspectos ambientales significativos, la cero emisión de efluentes líquidos, el menor consumo de agua son los principales beneficios de este proceso.

Sep 12, 2005