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By A. Sadik

The proliferations of media sources and non-profits organizations in Ghana have put the negative impacts of mining on the ?spot?; this has resulted in public outcry about mining. Although, the gold mining industry has responded by implementing several voluntary measures to ensure sustainable mineral development, these critics label such measures as ?green wash?. In this study, a content analysis of newspaper articles of the Ghana Web Database was carried out after the collection of a total of approximately 900 newspaper articles from it. The data were statistically analyzed to chronologically examine the main media view points and the changing perception of mining issues as reported by private and public media. The results showed government, mining industry (Gold), illegal miners and non-profit & community groups as the main media view points and total of twenty-eight related gold mining sustainability issues. The findings of this study could be used by the gold mining companies to improve upon the communications of their unknown sustainable mineral development measures and to design effective communications and education programs for the public.

Jan 1, 2009

By Calvin K. Lee

This Bureau of Mines report describes a simple fire-retardant treatment for wood. The treatment involves preheating the wood surface at high heat flux (~0.6 cal/cm2 sec) to form an in situ surface char layer (~3 mm thick) on the wood. Laboratory-scale fire tests show that the precharring technique improves the fire-resistance of virgin wood by decreasing and delaying generation of volatile gases through thermal insulation effect of the surface prechar layer.

Jan 1, 1978

By Masami Hayashi

The Bureau of Mines conducted laboratory studies to investigate methods for desilicating sodium aluminate solution derived from leaching a limestone-anorthosite sinter with 10-pct Na2C03 solution. Desilication tests were made at atmospheric pressure to determine the effects of time and additions of lime and desilication residues. A two-stage, countercurrent desilication procedure was developed to reduce the Si02 content sufficiently to meet specifications for cell-grade A1203. Both stages were conducted at boiling temperatures at atmospheric pressure. Reagent lime was charged as desilication seed to the partially desilicated solution in the second stage, and a product (desilication residue) precipitated by the lime addition was charged to the freshly leached solution in the first stage. Average A1203 loss in the desilication circuit was 5.8 pct, and the product solution contained less than 0.04 g/l Si02. Complete precipitation of A1203 by carbonation resulted in a hydrate containing less than 0.01 pct Si02. Calcination of this hydrate would produce A1203 meeting the 0.015 pct Si02 specification for cell-grade material.

Jan 1, 1982

By J. Chlopas, D. J. Barratt, M. V. Sharp

"This paper describes the modifications made to the Fox Mine copper concentrate bin in order to obtain a continuous flow condition. The design of these modifications is based on test results obtained on Fox Mine concentrate using the flow factor testing machine in the research facilities of Cominco at Trail, B.C.The original design consisted of a cylindrical steel bin on a concrete slab with two slot-discharge openings. Based on predictions of the maximum mass flow hopper angle for conical and wedge shaped hoppers for the concentrate on various potential bin lining materials, Ultra-High Molecular Weight (UHMW) Polymer was selected as a liner.Using the recommended angles for conical and wedge shaped hoppers, the profile of the bin base was changed to suit the existing slot openings.The initial method of fastening the liner resulted in failure of the connections. Subsequent modification to the zinc concentrate bin fastener system proved satisfactory and it has now been in operation for over one year without any separation of the lining material.Utilization of flow testing procedures on concentrate samples has demonstrated that proper design of storage bins or hoppers to achieve continuous flow can be incorporated into the design of new plants."

Jan 1, 1978

By Arnulf Muan, Egil Aukrust

Activities of COO in the three solid solution series COO-MgO, COO-MnO, and COO-"FeO" have been determined at 1200°C by equilibrating oxide samples with a metal phase (cobalt or a Co-Fe alloy) in atmospheres of known oxygen activities. The systems COO-MgO and COO-MnO are ideal, within limits of experimental error, whereas the system COO-"FeO" shows a slight positive deviation from ideality at the temperature of this investigation. KNOWLEDGE of activities of oxide components in solid solutions is necessary for the calculation of the cation distribution among coexisting oxide phases in many important metallurgical, ceramic, and geochemical systems. Very few activity-composition curves are available for such systems at the present time. A start on the prodigious job of obtaining such data has been made by studies of solid solutions with simple sodium chloride type structure containing NiO or "FeO" as a component.1-3 The present paper describes similar studies for solid solutions with sodium chloride type structure containing COO as a component. For the systems COO-MgO and COO-MnO, the activity solid solution is determined by the equation Here po and are the oxygen activities of the gas phase in equilibrium with the phase assemblages metallic cobalt plus oxide solid solution, and metallic cobalt plus pure COO, respectively. In the system CoO-"Fe07', the metal phase is a Co-Fe alloy rather than pure cobalt. In this case the activity of COO in the oxide solid solution is calculated from the equation where a& is the activity of cobalt in the metal phase. Because the system Co-Fe is close to ideal4 and the metal phase appearing in the present work contains less iron than cobalt even at the lowest COO concentrations of the oxide phases used may be set equal to N . Hence, Eq. [2] becomes The value of Nc, can be estimated from the relative stabilities of the oxides COO (see below) and I) EXPERIMENTAL METHOD Two different but closely related procedures were used in the present investigation to determine the activity-composition curves. In one method, the oxide solid solutions were equilibrated against

Jan 1, 1963

By Patricio Oyanader

La innovación es una disciplina que busca resolver retos a través de soluciones nuevas que generen un beneficio para la organización. En ese sentido, el presente texto señala los cuatro elementos clave (estrategia de innovación, desempeño, personas para innovar y los dispositivos habilitadores) en la gestión de la innovación de una empresa. Dentro de ese grupo de elementos, el tercero es el más importante -en tanto son las personas las que generan innovaciones en la resolución de sus problemas. Así, la novedad y el beneficio son conceptos que rompen los paradigmas de lo tradicional y viabilizan los desafíos operacionales como los de la gestión

Sep 1, 2013

By R. M. Lamya

The kinetics of copper cementation during atmosphere leaching of a Ni-Cu matte in CuSO4-H2SO4 solution was studied as a function of initial copper ion concentration, initial acid concentration, temperature, stirring rate, particle size distribution and pulp density. It was found that all these process variables influenced the rate of cementation. A two-stage rate of reaction was observed inmost of the experiments, with the rate of cementation in the initial stage being slower than that of the subsequent second stage. The increased rate of cementation in the second stage was attributed to the enhancing effect of the surface deposit. The cementation process was found to take place by two different rate-controlling mechanisms. At a temperature range of 50?70°C, an activation energy of 74.6 kJ/mol was obtained, indicating a surface reaction controlled process. At higher temperatures (70?80°C) a lower value of activation energy was observed (18.2 kJ/mol), indicative of a process controlled by diffusion through surface layers. The structural characteristics of the cemented deposit could not be determined in the investigated system where the deposit was mixed with the leach solid residue.

Jan 1, 2005

By Y. Shiraishi, Y. Sakurai

A new method, the gliding cylinder method, was proposed as a wide range viscometer for the measurements of molten salts, slags, and glasses. The method consists of two coaxial cylinders, cylindrical bob and a vessel containing a liquid sample. There is a narrow gap between bob and vessel. When the vessel moves against the bob, the generated force on the bob consists of three types of resistance: (1) Stokes’s resistance on the bob, (2) a capillary flow resistance though an annular gap between vessel and bob, and (3) lubricating resistance in a gap. The last two can be calculated on a theoretical basis but the first cannot be estimated by a simple calculation since a wall effect did not calculate easily. However, it can be assumed that the generated force depends on both the viscosity of a liquid and velocity of the vessel. Thus, the relation between viscosity and a force at desired velocity of the vessel was measured using several standard reference materials including glycerol aqueous solutions and standard reference oils. The results depended on the magnitude of the gap between the bob and the vessel. For the wider gap, it was shown that the viscosity is a linear function of a gradient of force with respect to a vessel velocity. In contrast, if the gap is small, the viscosity depends on the gradient (of force with respect to velocity). This implies that the non-linear phenomena would occur in Stokes resistance. Though detailed analysis is in a further investigation, a calibration method can be applied to determine the viscosity by this method, because good correlation was obtained among these quantities. Viscosity of molten salts, such as NaNO3and ZnCl2was measured by this method as high temperature demonstration. Keywords: viscometer, viscosity, sphere pull-up method, fused salts, molten slags, glass melts

Jan 1, 2004

By Mario Samamé Boggio

El presente texto describe la producción del alcohol como alternativa energética -en tanto replantea la política energética y la inscriba en el contexto histórico, geográfico, económico, social, tecnológico, cultural, ecológico del país que habitamos y del mundo que nos rodea. En ese sentido, se revisa la producción del alcohol a través de la biomasa, el cual mejora el rendimiento de la combustión en un motor de combustión interna, obteniéndose un mayor octanaje y el alcohol etílico se puede obtener a partir de biomasas de tres orígenes: carbohidratos en forma de azúcar (caña de azúcar, melazas), carbohidratos en forma de almidón (yuca, maíz, papa); y carbohidratos de las celulosas (madera y residuos agrícolas).

Mar 1, 1983

By David van Cleave, David L. Rome

Whether you buy your minicomputer from a manufacturer or another vendor, the first thing you must do is define your needs. With good planning, the initial cost will be low and your return on investment will be maximized over the long term. Involving all members of your staff who will he using the new computer in the planning phase is also important. Their participation will alleviate any potential concerns they may have about new equipment, and their suggestions will provide valuable input for your specifications. After you define your proposed system, survey available hardware and software. The survey will help you in the next step, preparation of specifications. The specifications, along with a quote request, are then sent to various manufacturers. Consider the Manufacturer When selecting your minicomputer, one important item to consider is the manufacturer. Remember, when you buy a computer, you're also buying the services of a computer company. A firm that makes a commitment to its customers and provides a product that is field tested before releasing it for sale is preferable. Examine the company's maintenance and support packages, since every machine requires preventive maintenance. Does your manufacturer or original equipment manufacturer (OEM) support service sites in your area? Has their service record been commendable? Will they provide training for your personnel and a supply of circuit boards so you can retain a degree of self-service autonomy? Three methods of buying a computer involve the manufacturer, an OEM, and the systems house. Buying direct from the manufacturer means you go straight to the source, using no middleman. This gives you maximum flexibility; you can consider every alternative and many possible combinations of computers, peripherals, and software until you find exactly the right system for you. The OEM buys computers direct from the manufacturer and builds them into his own computerized, special purpose product. He usually sells a complete package, including software and hardware, and often noncompetitive equipment as well (a scientific or engineering instrument, for example), designed for the mining market. Because he offers a packaged product, the OEM can often charge less for the system than if you put the pieces together yourself. In many ways, the OEM also provides a unique system. And while the OEM sells a packaged solution, he also usually has the special market knowledge necessary to modify the system to meet your unique needs, if necessary.

Jan 11, 1981

By X. L. Huang

This paper deals with the experimental and theoretic study of the contact pressure beneath the deep foundation of Beijing International Hotel, The experiments have been carried out in project and in model footing 6.6m2. The result of measurements shows the contact pressure at the edge is greater than that at the center. The theoretic analysis on the base of elastic theorey is in good agreement with the test if the proposed assumption used.

Jan 1, 2010

By Jeffrey M. Listak

This U.S. Bureau of Mines report describes the implications of in-mine ground control on the automated or remotely controlled operation of longwall mining equipment, Perhaps the greatest challenge to longwall automation researchers is the development of systems that will continuously function in the complex and unpredictable underground environment. The high degree of environmental variability, together with conditions brought about by the extraction process, makes complete automation of longwall mining a difficult task. The intellectual thought processes and split-second decision making required to avert disasters are lost when workers are removed from the face. As many mine operators can attest, minor problems, left unresolved, can eventually accumulate and lead to catastrophic consequences. The automation process will have to assess and manage various routine problems that are otherwise resolved through worker observation and experience.

Jan 1, 1990

By Adrian Coombs

The York Durham Sewage System (YDSS) Interceptor Tunnel Project is located in the Town of Richmond Hill, Ontario, Canada, just north of Toronto. Construction commenced in September 2006 and completion is planned for early summer, 2008. The project involved public and agency buy-in of construction technologies and methods that minimized dewatering, design and construction of sealed shafts with jet grout break-in and out blocks in order that Earth Pressure Balance (EPB) mode could be maintained by the Tunnel Boring Machine (TBM) during shaft entry and exit. This paper will discuss the advances that were made possible through the opportunity to apply and test these technologies in order to accommodate the aquifer and artesian conditions present on this project.

Jan 1, 2008

Mr. Murray said: Having recently returned from a visit to America, it may be of interest to members to hear something from me of the mining fields and metallurgical works which I had the opportunity of seeing, and the impressions which I formed concerning general practice and conditions there, as compared with our Australian standards in the mining industry, and in matters generally.The most striking feature of the North American continent is thehuge plan upon which Nature has built, the multiplicity of immense mountains, rivers, and lakes, the snow-covered tops of the former forming reservoirs for the latter during the summer months, being most impressive to the Australian visitor. Starting from Vancouver I travelled east for over 500 miles through the wonderful Canadian...

Jan 1, 1927

By R. H. Hiltz

One of the major hazards in underground coal mining is fire. The inherent hazard of fire is exaggerated by the nature of coal mining restricted areas, the highly combustible nature of coal itself, and a potential for explosive concentrations or dust and gas in the air it becomes imperative therefore to make every effort to eliminate the causes of fires, while providing the most effective means possible to control and extinguish those fires which may occur it has been demonstrated by prior work that the problem of control increases in proportion to the time necessary to institute control procedures. There are several areas of underground coal mining with obvious fire potential. Some of these, like belt heads, have reliantly undergone improvements in standby fire control devices Others, although having fire suppression systems available to them, have not received as complete a systematic study of their problems. Face machinery, particularly those without a water supply, falls in this latter category.

Jan 1, 1973

By J. Koster

Boron is an element whose metallurgical possibilities never have been investigated thoroughly, probably because of the difficulties experienced in the preparation of elemental boron and its intermetallic compounds. The southwestern United States contain the world's largest deposits of boron minerals. In general, the mineral is readily available, and mining costs are not excessive. The most important boron mineral of commerce is borax (sodium tetraborate); however, there are large deposits of colemanite (a mineral having the composition represented by 2CaO 3B203 5H20) in Clark County, Nov. This material was worked in times past by converting it to sodium tetraborate. In recent years the deposits have laid idle because of a mere readily available source of borax in the old lake beds of California.

Jan 1, 1940

By G. Hangone

Paper written on project work carried out in partial fulfilment of MSc thesis This paper investigates the effects of thiol collectors: xanthates, dithiophosphates, dithiocarbamates and mixtures of these on the froth flotation performance obtained with a bornite-rich copper sulphide ore from Okiep Copper Mine with a feed grade of 1.8%copper. Batch flotation tests were used to assess the performance in terms of mass-water recovery, sulphur grade-recovery and copper grade-recovery relationships and the Klimpel rate constant for copper recovery. The results showed that the di-ethyl-dithiocar-bamate (di C2-DTC) was the weakest collector of copper sulphide minerals. Highest copper recoveries were obtained with the di-ethyl-dithiophosphate (di C2-DTP), which were accompanied with more watery froths and lower copper grades demonstrating frothing properties in addition to collector action. Superior copper recoveries were obtained with the 90% ethyl xanthate (C2-X):10% di-ethyl-dithiophosphate (di C2-DTP) and 90% ethyl xanthate (C2-X):10%di-ethyl-dithiocarbamate (di C2-DTC) collector mixtures compared to that obtained with ethyl xanthate at an equivalent collector dosage of 0.139 mol/ton ore (a dosage equivalent to 20 g sodium ethyl xanthate per ton ore). A superior copper grade was obtained with the 90% ethyl xanthate: 10% di-ethyl-dithiocarbamate collector mixture at a dosage of 0.0695 mol/ton ore compared to that obtained with ethyl xanthate at the same equivalent dosage. Keywords: flotation, collector mixtures, copper sulphide ore

Jan 1, 2005

By Virgil Miller

Bureau of Mines Reports of Investigations 3244, 3245, 3246 and 3264 give data of detailed studies on smelting in the lead blast furnace handling zinciferous charges at Trail, B. C. The present paper gives more on analyses of the gases leaving the top of the charge and on accretions formed on the walls of the blast furnace. New data are presented to show the effect of the temperatures at the tuyere zone on the lead content of the slags made. The greater part of this paper, however, deals with a much debated subject, namely air used in lead blast furnaces. Original data are presented to show the effects on smelting lead 'products when air is supplied to a lead blast furnace under volume versus under pressure control.

Jan 1, 1940

By Virgil Miller

Bureau of Mines Reports of Investigations 3244, 3245, 3246 and 3264 give data of detailed studies on smelting in the lead "blast furnace handling zinciferous charges at Trail, B. C. The present paper gives more on analyses of the gases leaving the top of the charge and on accretions formed on the walls of the blast furnace. New data are presented to show the effect of the temperatures at the tuyere zone on the lead content of the slags made. The greater part of this paper, however, deals with a much debated subject, namely air used in lead blast furnaces. Original data are presented to show the effects on smelting lead 'products when air is supplied to a lead blast furnace under volume versus under pressure control.

Jan 1, 1940

By Werner Joseph

El presente trabajo describe los aspectos que comprenden la metalurgia del antimonio y sus compuestos. Para ello, se revisa su historia, propiedades físicas y químicas, origen y materias primas, pirometalurgia de los minerales sulfurados y oxidados, hidrometalurgia y electrometalurgia, métodos extractivos especiales, producción de los principales compuestos, mercado y proyecciones futuras.

Mar 1, 1985