Search Documents

By V. B. Achanti, A. W. Khair

Laboratory studies were carried out at West Virginia University to investigate the rock fragmentation mechanism by continuous miners using an automated rotary cutting simulator. The primary factors influencing the fragmentation process were found to be: bit spacing, bit geometry, depth of cut and cutting drum rotational speed. This paper presents the influence of these parameters in achieving optimum energy consumption and minimizing dust generation during rock fragmentation process. Tree bits were used simultaneously on Indiana limestone while the bit tip angle was varied from 60° to 900. Bit spacing was varied from 2.54 cm (1 in.) to 5.08 cm (2 in.) while the cutting process was assessed for varying cutting depths. Restorable dust generated during the course of the experiments was analyzed utilizing cascade impactors. Assessment of these parameters has led to a better understanding of the cutting mechanism by continuous miners in terms of energy consumption and dust generation.

Feb 24, 1997

By A. U. Seybolt, R. E. Honnemon

THE purpose of this communication is to present activity data of nickel in the Ni-A1 binary system that was obtained for oxidation studies in this system. This data has been calculated from previous aluminum activity data at 1000°C1,2 by two types of Gibbs-Duhem integrations. These results should be of particular current interest to oxidation studies of aluminide coated nickel-base superalloys3 as well as other problems. The aluminum activity of Steiner and Komarek1 is plotted in Fig. 1 as a function of composition in Ni-A1 alloys at 1000°C. The dashed parts of the aluminum curves represent our approximate extrapolations from the directly measured regions. In the terminal solution regions (a and L phases) standard parabolic solution functions of the following form are assumed: where i is the component subscript, Ki is a constant at a fixed temperature, and xi is the atom fraction. The resultant nickel activity curve at 1000° C from the Gibbs-Duhem integration4 of the aluminum data is shown in Fig. 1. The solubility ranges of the phases present in the Ni-A1 binary at 1000°C are also denoted at the bottom of Fig. 1. Corresponding values of the nickel activity, aNi and yNi, are listed in Table I at useful compositional intervals. including phase boundary values. The aNi and yNi data listed in Table I are subject to the uncertainties present in the experimental aluminum activity data1 and to deviations from parabolic solution behavior in the terminal solutions. The errors introduced into aNi and yNi due to the parabolic solution assumption are expected to be relatively small (<20 pct of the values given) in all the phases except the liquid phase. Some deviation from parabolic solution behavior in the liquid phase is indicated

Jan 1, 1970

By R. Farrar

The survey work on protective canopy design was conducted in a 2-month period commencing November 15, 1973. The reported re¬sults under this contract are intended to provide guidance to coal mine operators in complying with federal regulations pertaining to incorporation of protective canopies on underground coal mine electric face equipment. All coal mine electric face equipment manufacturers and 11 coal mines were visited in the course of conducting this survey. Canopy designs currently being manufactured and those now being used underground were examined and discussed with manufacturers, mine operators, machine operators, and safety committeemen. The general objective was to find out what kind of canopies are now being made and used underground, what the operational problems are, and what can be done to secure improvements. Specifically, the survey scope was as follows: a. Survey all electric face equipment manufacturers. b. Survey 10 coal mines (seam height 60 inches and greater). c. Identify current production canopy configurations and minimum mine entry dimensions for each model and type of electric face equipment. d. Assess in-mine operation of canopies developed by manufacturers and/or coal companies. e. Specify optimal canopy configuration and minimum mine entry dimensions for each type and model of electric face equipment.

Jan 1, 1974

By Lester Brown

La dependencia de los países ricos o desarrollados respecto de los países pobres es cada vez mayor -en tanto los primeros agotan sus abastecimientos requeridos por la industria y dependen de las reservas de minerales de los países pobres. La dependencia también implica que la economía de los Estados Unidos se está volviendo más vulnerable a las fuerzas externas como los pactos colectivos en los países suministradores, huelgas en las minas extranjeras o en la industria naviera. Por ello, los países pobres, dándose cuenta del progreso en el trato de su posición por algunos minerales, negocian en términos más favorables para sus materias primas. En ese sentido, el presente texto describe la dependencia económica de los países desarrollados hacia la materia prima de los países subdesarrollados.

Nov 1, 1973

By Lui Chocano

"El presente trabajo señala los beneficios de la aplicación de la tecnología de la virtualización en la empresa minera Yanacocha, la cual está enfocada en brindar soluciones tecnológicas que aporten beneficios directose indirectos en las operaciones del programa en conjunto y las áreas de Operación. Esta tecnología de la información provee recursos para el procesamiento de la información y soporte de los servicios ofrecidos a la operación. Así también la virtualización de servidores ofrece una ventaja diferencial para los negocios como la optimización de los recursos actuales en los centros de datos (servicios y servidores), de forma que permiteextender la capacidad para albergar y brindar nuevos servicios a nuestras áreas internas. "

Sep 24, 2008

This paper provides an update to a paper by the author on an overseas explorer&apos;s perception of New Zealand, presented at the 1997 New Zealand Minerals &amp; Mining Conference. New Zealand has one of the most open and internationally competitive economies in the world. The petroleum exploration industry in New Zealand is booming with a record number of wells planned for 2000. New Zealand is keen to encourage investment in mineral exploration to develop its natural resources. A study of the geological potential of New Zealand estimated the value of known and potential resources of metals at $86 billion. Gold has the greatest potential, with a total resource estimated at $33.5 billion. The price of gold has averaged NZ$554 since the beginning of 1998, and NZ$593 in the last year, which is very competitive with other countries. An assessment of country risk compared New Zealand with twenty other countries in ten risk categories: sovereign risk, land access, environmental issues, land claims, mining legislation, social risk, infrastructure, civil unrest, natural disasters and workforce. New Zealand ranked fifth, showing it has low country risk. This provides a high degree of certainty for investment, which is important for the perception of New Zealand as an exploration destination. Corruption was considered separately, and New Zealand ranked third out of ninety countries, showing it is one of the least corrupt countries in the world. New Zealand has a favourable business environment, good geological potential, low country risk and no corruption. Despite this, New Zealand has not registered on the radar screens of overseas mineral explorers, and the positive factors appear to have been overlooked. New Zealand has considerable undeveloped mineral potential, and with the current rise in commodity prices, it is hoped New Zealand can participate in a resurgence in mineral exploration.

Jan 1, 2000

By Jasper L. Stuckey

PYROPHYLLITE, first identified as soapstone,&apos; later as agalmatolite,2 and finally as pyrophyl-lite, has been known to occur in North Carolina for more than 130 years and has been produced intermittently in commercial amounts for the past 100 years. Pyrophyllite mining, however, has become a major industry in North Carolina only during the past 25 years. North Carolina and California are the chief producing states. Current annual production averages 125,000 tons, of which slightly more than 90 pct comes from North Carolina. Distribution and Geologic Setting: All known pyrophyllite deposits in North Carolina are associated with rocks of the Carolina Slate Belt,&apos; which is composed of a vast series of metamorphosed volcanic and sedimentary materials, occurring as two zones extending in a northeast-southwest direction across the state. The larger of these zones, lying in the central Piedmont region, varies from 8 to 50 miles wide. The smaller zone lies along the eastern edge of the Piedmont region and is partly covered by coastal plain sediments. The rocks in both zones consist of a great volcanic-sedimentary series, composed of air-laid and water-laid tuffs and breccias, lava flows, and slates. On the basis of composition, they may be classed into three groups: 1) tuffs, breccias, and lava flows of acid or rhyolitic composition; 2) tuffs, breccias, and lava flows of a basic or andesitic composition; and 3) water-laid slates composed of fine grained materials derived chiefly from the acid tuffs and breccias and

Jan 1, 1959

By Juan Carlos Ramírez

El presente trabajo señala la importancia e influencia del Sistema Privado de Pensiones (SPP) y las AFP para el desarrollo e inversión del sector minero. Para tal fin, se analiza la interfase necesaria entre cada agente del sistema y así lograr tres objetivos: la garantía real de los fondos, fondos disponibles para el sector productivo minero y una alternativa más de colocación de fondos para las AFP. Asimismo, se minimiza la creación de mecanismos de control adicionales para conectar el sector minero hacia otros sectores económicos-financieros, no solo a través del sistema bancario tradicional, sino con otros campos financieros, bolsas y SPP.

Nov 24, 1993

By H. Warren Newcomen

Assessments of the stability performance of open pit highwalls have traditionally been based on consideration of surface movement rates. Although generally accepted in industry, this approach presents challenges for establishing appropriate threshold values to allow for safe mining operations and does not address the issue of total strain. Surface movement monitoring data from a limited number of open pit mining operations in North and South America has been evaluated in terms of highwall strain, rock mass quality and inferred mechanism of instability. Threshold strain levels for key stages of highwall stability proposed from previous work have been reviewed and are generally endorsed based on evaluation of additional data. An empirical highwall strain criteria for the assessment of highwall stability performance is postulated based on the observed trends in highwall strain data from the case histories presented.

May 1, 2004

The London Metal Exchange began its first official session of aluminum trading on Monday, October 2, LME prices based on 3-month forward contracts opened Monday at 52.4 cents per pound, fell midway through the week to 52.3 cents and ended Friday at a high of 52.7 cents. For the week, LME metal averaged 52.5 cents. Although Reynolds Metals Co. and Aluminum Co. of American continued in September to value unalloyed 99.5 percent aluminum ingot at 53 cents per pound, other producers were at higher positions of 55-57 cents. Alcan Aluminum Corp. of Alcan Aluminum, Ltd., a Canadian producer, increased prices for its U.S.-marketed ingot by 2 cents to 55 cents per pound, effective September 21. New York merchants increased ingot quotes by approximately 0.5 cents to 52.8-53.5 cents per pound.

Jan 1, 1978

By Walter E. Vanderpool

Three drilled foundations for an elevated water-tank were instrumented, tested and monitored during construction and the first two years in service. One shaft was load tested by the Osterberg method. A void was detected in one shaft by cross-hole sonic logging, pulse-echo logging and concrete coring. The void was instrumented, hydrostatically tested and pressure grouted. The shaft was ?abandoned? and replaced by two smaller shafts with a straddle beam cap. One of the replacement shafts and the cap were instrumented. The strain that appeared in the abandoned shaft, the replacement shaft and the cap were monitored during the remainder of the construction, through the commissioning test and the first two years of service. The results demonstrate the precision and sensitivity of the vibrating wire strain gage.

Jan 1, 2004

By Alberto Ramirez Sauri

El concepto de rentabilidad se relaciona con un sistema de medida de rendimiento expresado en términos de utilidad de una inversión, una actividad económica o negocio. Mientras que la productividad se relaciona con la cantidad de producto extraído con determinados factores de producción y factores. Por ello, el presente texto analiza las tendencias de los diferentes grados de utilidad con el capital invertido, los márgenes con respecto al ingreso y su relación directa con la productividad del sector minero. Así también es necesario que el sector minero uniformice sus criterios contables para poder llegar a obtener indicadores de rentabilidad, productividad y de otro carácter económico, que permita a cada unidad ubicarse con relación al promedio del sector, facilitándole al empresario el conocimiento necesario para optimizar su gestión en beneficio del sector y la economía del país.

Nov 1, 1972

By Gordon I. McPhail

"El presente texto señala un método de conservación del agua y diseños de drenajes para el control de ARD (Drenaje Ácido de Rocas). El método fue aplicado en el desarrollo de un proyecto aurífero en Argentina, donde dada la cercanía de la mina con el pueblo, se eliminó el uso del cianuro y se empleó el procesamiento off-site que contó con una gran cantidad de escenarios de desarrollo viables. Este planeamiento considera un proceso integral de molienda, concentración y relaves que reemplaza las instalaciones para el almacenamiento de relaves (TSF) como entidades independientes. Así también cuantifica las compensaciones hechas entre los beneficios y efectos sociales, económicos y ambientales. "

Jul 1, 2016

By S. L. Huang

The location and shape of potential failure surfaces in soil slopes were directly determined based on the stresses induced in the soil mass and the strength of the soil itself. Stress calculations were carried out by the finite element method with the Drucker-Prager nonlinear material model. The Mohr-Coulomb failure criterion and Mohr&apos;s circle stress analysis were then applied to the calculated stresses to determine the characteristics of the failure surface.

Jan 1, 1989

By Nicholas P. Callas

This report presents research results obtained in the investigation of deviation control of boreholes in the rotary drilling process. The approach taken in this research is the passive method of placing stabilizers in the bottom-hole assembly to control deviation. Extensive use was made of the drill string mechanics theories of Lubinski and Woods. Analog, digital and hybrid solutions to variety of boundary value problems were investigated in order to determine the best models for bottom-hole assemblies. Field drilling data was analyzed and the results obtained from various models were compared to the actual drilling results. Various accomplishments of this work have been published in open energy industry literature, with more publications to follow.

Jan 1, 1981

By Keith L. Harris

Economic activity in the United States picked up in the third quarter, according to the latest estimate released by the Department of Commerce. Real gross national product (GNP)--the Nation&apos;s output of goods and services--grew at a seasonally adjusted annual rate of 4.3%, or $17.6 billion, compared with a rate of 1.9% for the second quarter of 1985 and 1.6% for the third quarter of 1984 (table 1). The 4.3% rate is one percentage point above the preliminary estimate reported in the August/September issue of Minerals and Materials. Most of the upward revision was due to the change in business inventories and Government purchases, while the figure for net exports was revised downward substantially. The 4.3% growth bettered by 1.5% the average rate of growth in GNP from 1974 through 1984 and was 1.1 % above that of the period from 1975 through 1984 and 0.7% above that of 1980 through 1984. Of importance to the minerals industry was the $14.4-billion growth in personal consumption expenditures, $10.2 billion of which was for durable goods (especially domestically produced automobiles) and the growing residential investment. The net export deficit continued to grow, however, and investment in nonresidential structures, producers&apos; durable equipment, and business inventories declined. Prices, as measured by the GNP fixed-weighted price index, increased at an annual rate of 3.1% in the third quarter, compared with 3.9% in the second quarter. The slower rate of inflation resulted mainly from a decline in energy prices, following second-quarter increases. Fourth-Quarter Prognosis Many of the economic data available for October and November indicate that the economy is growing modestly and will continue to grow over the next 3 to 6 months. The composite index of leading indicators, designed to predict economic activity within 3 to 6 months, rose 0.3% in October, the sixth consecutive monthly advance, according to the Department of Commerce. Six of the 11 available leading indicators were positive: Stock market prices rose, as did sensitive material prices, credit outstanding, and manufacturers&apos; new orders for consumer goods and materials; initial claims for unemployment insurance decreased, and firms were getting slower delivery of goods. Four of the indicators were negative: Business formations, homebuilding permits, contracts and orders for plant and equipment, and money supply all declined. The average hours worked per week, already at a high level, remained unchanged.

Jan 1, 1985

By Enrique Monge

El presente texto señala las plantas de tratamiento mecánico de acero, así como las plantas de rodamiento para barras y planchas semiterminadas, las de rodamiento para la producción de barras comerciales, la producción de formas estructurales en la industría del acero en los Estados Unidos de Norteamérica.

Jan 1, 1958

By Timothy W. Ellis

Wire Bonding is the dominant IC interconnection process presently used in the semiconductor assembly industry (1). The flexibility, adaptability and cost of wire bonding will continue to keep it as the key process for the interconnection of integrated circuits to substrates. However, wire bonding still has certain technological hurdles to overcome if it is to continue following the semiconductor roadmap (2). Particular issues which need to be addressed include low overall tensile strength, low elastic modulus, low shear per unit area and mechanical loop stability of Gold based micro-alloys. The ability to produce ?Deformation Process Metal-Metal Matrix Composites? (DMMCs) is based upon the deformation nature of immissible metallic systems. For reference, the Gold (Au)-Molybdenum (Mo) phase diagram is shown in Figure 1 (3). By inspection of the diagram, Au has a very low solubility for Mo, while Mo has essentially no solubility for Au. This is the metallurgical analog of oil and water. In the Au-Mo case, this is particularly troublesome when producing precursor ingots of the alloy to be formed into wire products. In Table 1, the melting points and densities are shown for Au and Mo. As shown, the melting point of Mo is significantly higher than Au, and is very close to the boiling point of Au (2856°C). However, Au?s density is higher than that of Mo. As such, conventional casting techniques are not suitable, since solid Mo would float off the surface of an Au melt thus depleting the matrix of its alloy addition. In this work, two-phase composite wires were produced by deformation processing to develop an interconnection wire with elevated tensile strength, modulus and shear to those commonly available in the market (4). This technology has been used previously in the production of high strength electrical conductors particularly for high field pulsed magnets (5).

Oct 1, 2003

El presente artículo señala que el proceso de exploración en superficie de la mina de Cercapuquio para determinar nuevas zonas mineralizadas, es de difícil actuación a causa de la falta de ganga en este tipo de mineralización. Para ello, se consideró oportuno proceder a una exploración de carácter geológico de la zona en estudio, antes de empezar los trabajos sistemáticos de exploración geofísica. Asimismo, los procedimientos empleados en las etapas de exploración, son las siguientes: trabajos geológicos, geofísicos y mineros.

Oct 1, 1955

By Y. M. Jiang

A users friendly PC Computer Program has been developed to implement a systematic design of the powered support. The required input data are: (1) thickness, RQD, and compressive strength of the immediate roof; (2) mining height; and (3) type, thickness, and tensile strength of the main roof. Several important parameters for support selection under a given geological condition are generated through the implementation of the program, including type of support most favorable for the geologic condition, minimum inclination angle of the legs with respect to the horizontal axis, suitable setting load ratio of the front to rear leg for the 4-leg supports, optimum setting load, and support capacity.

Jan 1, 1989