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By Timothy D. Arnold

Barrick Gold’s Bullfrog underground mine, near Beatty, NV, was established as an after-thought to the main open pit. As open pit ore dwindles, the underground mining became increasingly more important as an ore source, and to the overall economics of the project. This situation is similar to many other mines. Today, there is a move towards underground mining in the United States. There are inherent problems in starting and operating underground mines in the shadow of any open-pit operation. Several attempts were made at the Bullfrog Mine for productive increases. Some were successful, while others were not.

Jan 1, 1996

By R. E. Mitchell

Environmental Impact Assessment (EIA) is the accepted method for evaluating proposed mining and other industrial projects to obtain regulatory approval and to help companies plan for responsible development. Another evaluation system becoming increasingly more common for proposed projects is the Environmental, Social and Health Impact Assessment (ESHIA). An ESHIA differs from an EIA for its more comprehensive and inclusive approach to evaluate potential impacts on public health, and its ecosystem services approach to assessing biodiversity impacts. An ESHIA may also be required by certain lenders for financing major projects. Conducting an ESHIA for a proposed mining development is not without its challenges, with costs, scheduling, regulatory concordance and other constraints to be considered. This paper examines some benefits and challenges of ESHIAs and summarizes lessons learned using a case study approach.

Jan 1, 2012

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

By D. J. Englund, R. A. Davis

"A three-dimensional CFD model of a straight grate furnace for indurating iron-oxide pellets was developed for exploring conditions of furnace operation for fluid flow, heat transfer and reactions. The model includes reactions for natural gas combustion in the gas phase and calcination and magnetite oxidation as well as drying in the pellet bed. The performance of the model was investigated with a series of pellet production rates that included adjustments to the fuel rates to achieve proper induration temperatures in the pellet bed. The model may be used to discover opportunities for process improvement.IntroductionIron oxide pellets are a feedstock to blast furnaces for iron making. Pellets require physical strength characteristics needed to maintain their integrity during storage, handling, transportation and smelting. Pellets are produced from iron ore in a series of mineral processing operations that form wet green balls from slurries of iron-ore concentrate with binders, such as bentonite, and possibly fluxing-agents such as limestone and dolomite. The green balls are dried, fired at high temperature, and then cooled in an induration furnace to achieve the strength and chemical composition required for efficient reduction and slag separation in blast furnaces. Induration furnaces are generally straight grates or grate-kilncooler configurations. These furnaces operate with pellet beds passing through a series of temperature zones to control drying and chemical reactions in the bed.Process air passes through the zones in an overall counter flow direction to the pellets for efficient heat transfer and energy recovery from the cooling stage. Consequently, the zone conditions and the overall furnace performance are highly coupled. Thus, it becomes challenging to predict how changes to any single zone may affect the rest of the furnace. To gain a better understanding of machine performance and coupling, a three-dimensional, steady-state model of a complete straight grate induration furnace was created using computational fluid dynamics (CFD)."

Jan 1, 2015

By George H. K. Schenck

Diminishing returns in management's fight to lower manufacturing expenses have added luster to savings that can be achieved in delivered costs through creative management of the distribution function. This is especially true for companies engaged in the production of bulk commodities, for which transport costs may represent 25 to 50% or more of total delivered price, A. E. Cascino, vice president of International Minerals and Chemical Corporation, recently gave an example of why top management in his firm is concerned with distribution: "The price of a ton of phosphate rock, f.o.b. mine, is about $7. The cost of warehousing, freight, and handling frequently totals an additional $11 . . . . If one of our competitors . . . discovers a way in which he can cut his distribution costs by $3, we're dead! Even if we wanted to offset our competitor's more efficient means of shipping with reduced f.o.b. price for our product-we don't have that much profit margin . . . ." In a special report on the revolution now occurring in transportation of goods, Business Week stated in its September 24 issue: "Moving and storing goods on their way from mine and mill through various sub-assemblies to their final markets costs anywhere from $50 billion to $75 billion a year- $100 billion if paperwork costs are included.

Jan 1, 1967

By Jedson Alessandro Damasceno

Atualmente, a maioria dos pátios utilizam recuperadoras com roda de caçambas para remover o minério das pilhas de estocagem. Tipicamente, estas máquinas são operadas manualmente, com todos os movimentos controlados por operadores, o que faz com que o processo seja totalmente dependente de sua experiência, tornando difícil manter o processo em operação ótima. Para alcançar uma melhor performance, foi implementado um sistema automático que controla todos os movimentos de recuperação. Um importante desafio encontrado durante a construção dessa solução foi a de estimar a taxa de recuperação em tempo real, uma vez que esta informação é essencial para o algoritmo que controla o movimento de giro da máquina. Uma medição real dessa taxa está disponível, mas, a balança localizada na lança fica distante da roda de caçambas. Em outras palavras, a medição real está disponível com um grande atraso (aproximadamente 13 segundos). Este delay é inaceitável para o algoritmo de controle que necessita de uma medida em tempo real da taxa de recuperação na roda de caçambas. Diante disso, foi necessário implementar um sensor virtual. Este sensor foi implementado usando um sistema neuro-fuzzy para estimar a taxa de recuperação em tempo real utilizando outras variáveis disponíveis, tais como a pressão na roda de caçambas e medidas de penetração obtidas por radares. As estimativas obtidas ficaram muito próximas dos valores reais, e este sensor pôde então ser utilizado pelo algoritmo de controle.

Aug 17, 2017

By James A. Wasson

Because of the danger to life and property in a coal mine if an oil or natural gas well should be accidentally intersected during mining operations, certain precautionary measures should be carried out prior to entering previously unmined areas. The locations of all wells both at the surface and at the depth of the coalbed should be accurately determined. The condition of the well should be learned from surface observations, and more importantly, from subsurface examination by geophysical logging devices where possible. It is also desirable to learn the physical properties of the hydrocarbon-bearing rock formation and the hydrocarbon fluids. The major hazard presented by oil or natural gas wells to mining operations is that of explosion and fire due to the rapid release of gas into the mine atmosphere. Wellbore pressure, the principal index of danger, should be determined by one or more of the methods described and by a service company such as those listed in the appendix. Because of high pressures involved and the consequent hazard, much emphasis has been placed on underground storage of natural gas in areas containing minable coalbeds. Maps are shown of the principal coal producing areas and the locations of currently active gas storage reservoirs. A checklist has been included of factors to be considered when mining coal in an area where oil or gas wells exist.

Jan 1, 1973

By Marcela Alves Silva

Os aços inoxidáveis duplex - AID são ligas de Fe-Cr-Ni com no mínimo de 10,5% de Cr, promovendo uma película superficial aderente de Cr2O3, com proteção a corrosão e proporção microestrutural de austenita e ferrita próximas a 50%, potencializando as propriedades mecânicas e resistência à corrosão.Possuem boa soldabilidade, porém pode provocar um desbalanceamento microestrutural e a precipitação de fases deletérias, acarretando o declínio das propriedades, principalmente na zona afetada termicamente – ZTA. Desta forma o presente trabalho tem como objetivoavaliar à influência da energia de soldagem sobre a ZTA da junta soldada de AID, comparando soldas realizadas pelo processo TIG e FCAW levando em consideração o balanceamento das fases ferrita e austenita. Para tanto, foram realizadas soldas com parâmetros comumente utilizados nas indústrias em geral. As amostras apresentadas foram soldadas de acordo com o padrão da Thermon Indústria Mecânica, uma das colaboradoras deste projeto. Conclui-se que a comparação entre os dois processos distintos resultou em fatos já esperados, embasado na revisão bibliográfica, onde o corpo de prova soldado pelo processo TIG apresentou menor região propensa a fragilizações, menor ZTA. As frações de austenita e ferrita em cada corpo de prova foram similares nesta região.

Aug 17, 2017

By Caroliny Gomes de Oliveira

O presente trabalho avaliou a utilização de uma célula eletroquímica portátil de ensaio de EPR-DL aplicada na detecção da susceptibilidade à corrosão no aço inoxidável superduplex UNS S32750. Amostras do referido aço foram tratadas termicamente na temperatura de 850°C por tempos de 1, 10, 60 e 600 minutos para criar diferentes padrões de precipitações de fases deletérias. Foram utilizadas as técnicas de microscopia ótica (MO), microscopia eletrônica de varredura (MEV) e espectroscopia por dispersão de energia de raios-x (EDS) para análise da microestrutura. Os resultados mostraram que a célula portátil de EPR-DL foi capaz de detectar com sucesso a presença das fases deletérias precipitados no aço. Além disso, quanto mais longo o tempo de tratamento, maior foi o grau de precipitação e, consequentemente, maior a susceptibilidade à corrosão no AISD, em função da maior razão Ir/Ia obtida.

Aug 7, 2018

By B. K. Shibler, K. C. Vincent, W. W. Agey

"INTRODUCTION As a part of the investigation of domestic manganese deposits, examining engineers of the Bureau of Mines collected samples of ore from three from three properties in the general vicinity of Tracy, Calif.The Buckeye mine is 23 miles of Tracy, just inside the northeast boundary of Stanislaus County. The mine is owned by K.O. Winship estate of San Francisco and is leased by Verner Allen, also of San Francisco.The ore is principally manganese carbonate occurring in interbedded layers in white chert, with the original,carbonate mineral altered in place. Four samples, representing four types of ore, were submitted, as follows: A, black oxide; B, pink carbonate; C, gray carbonate.The Wilfred Murphy property (also known as the Murmac claims) is approximately 30 airline miles south of Tracy. The property can be reached by road from either Livermore or Patterson and is on the divide separating Santa Clara and Stanislaua Counties Calif. The ore occurs in lenses along a white-chert formation. A 2-ton sample of ore for testing was taken from a dump accumulated from assessment and development work. The Ladd mine, 13 miles from Tracy in San Joaquin County is owned by Pat J. Connolly of Tracy and is leased by Mack C. Lake of San Francisco. The ore is essentially a chert impregnated with manganese oxides and the association is therefore exceedingly intimate and complex. Samples from each of the three adit levels of the mine were submitted for ore-dressing study.As the samples differed widely in physical character and response to ore-dressing methods of treatment, beneficiation of ores from each property was considered as a separate problem. Hence results of the investigations will be prescribed in separate sections of this report."

Nov 1, 1947

By Eulogio Velasco, Jose Nino, Marcos Cardoso

"Recycling of aluminum scrap for production of secondary alloys used for automotive applications is increasing continuously. Automotive alloys require a strict control to remove alloy impurities, inclusions and excess of magnesium. The advantage of aluminum is its recyclability with large energy and emission savings with minimal loss in material properties. The aim of this work is to study the magnesium removal from recycled aluminum by chlorine injection in a reverberatory furnace, and removal by an oxidation process at high temperature in an industrial rotary furnace.The magnesium removal by gas injection is carried out by the reaction between chlorine and magnesium, with its efficiency associated to kinetic factors. In the rotary rapid oxidation of aluminum and magnesium elements at high temperature is characterized by the formation of surface films composed of magnesium oxide. Additionally this work reviews the benefits of an efficient demagging process.IntroductionThe advantages of using light alloys for automotive applications include fuel economy improvement, greenhouse gas reductions and polluting emissions. These characteristics makes the aluminum alloys an attractive option for automotive components such as powertrain products and other critical parts like cylinder heads and blocks. [1]Aluminum alloys coming from recycled automotive components, used beverage cans (UBC) and wrought alloys have positive effects in the energy savings and current environmental trends. Producing a scrap recycled aluminum ingot consumes approximately 5% of the energy required to produce a primary aluminum ingot from bauxite ore. [2]"

Jan 1, 2011

By D. P. Lindroth

The Bureau of Mines is engaged in research on ground probing radars for detection of geologic hazards in advance of mining. Penetration distances and interpretation models depend on the dielectric properties and wave propagation characteristics for coal measure stratified media. Relative dielectric constants and dissipation factors were measured under ambient conditions for Pittsburgh Seam coal measure rock over the frequency range of 20 to 100 MHz by the susceptance-variation method. The rock types measured were representative sedimentary rock located above the Pittsburgh Coal Seam. Extreme values for the computed attenu-ation distance ranged from 1.7 m at 100 MHz for siltstone to 230 m at 20 MHz for a particular limestone.

Jan 1, 1984

Gold was first discovered on the Shotover by Thomas Arthur in 1862, and soon there were over 3000 miners working on the river. It has often been called the richest river in the world. Most countries probably have one of these, but it was certainly the richest in New Zealand. In the early days some miners collected as much as 200 oz/d from a sluice box, and the early river gravels must have been extremely rich before the gold bearing terrace gravels were sluiced into the river. Otago produced about 10 Moz out of the NZ total of over 30 Moz. Most of this was alluvial and possibly one third or more came from the Shotover. The extremely cold winter and danger of flooding made it a dangerous river to work. During 1863 when heavy rain melted snow in the high country, the river rose 35 ft overnight and drowned many miners camped on the banks. These hazards still exist and dominate the method of working. The early hand miners cleaned out much of the riverbed, and the advent of the hydraulic elevator enabled deeper parts of the river to be worked over. Extensive sluicing of high terraces also took place particularly around Skippers. Several companies have attempted operations on the Shotover. Many of these were distinctly unsuccessful, such as the suction dredge at Maori Point about 1930 and the Skippers Limited fluming in about 1934. At least two attempts were made to divert the river with the Sandhills cut above Skippers and the Oxenbridge Tunnel down near Arthur's Point.

Jan 1, 1983

By Ana Maria Gontijo Figueiredo

Muitos dispositivos biomecânicos têm sido produzidos com ligas superelásticas (SE) de NiTi. Na maioria das aplicações, o material é submetido a solicitações mecânicas cíclicas, tornando seu comportamento sob fadiga um parâmetro importante. Neste trabalho são apresentados resultados de ensaios de fadiga por flexão rotativa de um fio SE, ensaiado a seis temperaturas diferentes, sob amplitudes de deformação (?a) variando de 1% a 12%. As curvas mostram que a vida em fadiga do material na fase martensítica estável (ME) é cerca de 100x maior do que na fase austenítica estável (AE). A curva do fio SE se aproxima da curva do fio AE para pequenas ?a e, com o seu aumento, se aproxima da curva do fio ME quando ?a aumenta. As superfícies de fratura obtidas foram observadas ao microscópio eletrônico de varredura e foram calculadas as áreas correspondentes à fratura por fadiga (af). Os resultados mostram que, para o fio nas fases AE e ME, af decresce continuamente com o aumento da ?a. Para o caso do fio SE, af permanece relativamente constante para valores intermediários de amplitude de deformação (2% a 8%). Para uma mesma deformação, af cresce com a redução da temperatura, com o consequente aumento do número de ciclos para falha.

Aug 8, 2018

By Márcio Zamboti Fortes

A alguns anos os setores residencial e industrial tem se deparado com mudanças de paradigmas que tangem a necessidade de melhorias em suas atividades, com o intuito de desenvolver processos com menor impacto ambiental, sustentáveis e com eficiência energética, objetivando reduzir o consumo de energia elétrica. O uso de tecnologias baseadas em fontes renováveis para a geração de energia elétrica, tais como a solar e a eólica, tem apresentado-se como uma alternativa a ser implementada por estes setores para atender às exigências do mercado, se beneficiando da difusão da tecnologia e uso destes equipamentos, para a consciente utilização da energia elétrica. A instalação e avaliação de novas fontes de geração de eletricidade estão sendo desenvolvidas pelo projeto Cidade Inteligente de Búzios através da implantação de painéis fotovoltaicos e aerogeradores de pequeno porte em unidades consumidoras residenciais, comerciais e industriais e alguns resultados estão apresentados neste texto.

Sep 25, 2017

By J. -C. Tricket, W. A. Düweke, S. Kock

The high-resolution three-dimensional (3-D) seismic reflection data acquired for Impala Platinum between 1998 and 2002 in the western Bushveld Igneous Complex form an integral part of Impala?s mine planning and development programme. These data are of sufficiently high quality to provide unprecedented 3-D models of the geological structure of the Merensky Reef and UG2Chromitite Reef, from which the mine deduces the size, geometry and distribution of mineable blocks. Conversely, the seismic data details zones of un-mineable ground caused by structural disturbances in the form of potholes, fault zones and pegmatoid intrusions. Furthermore, variations in dip and strike are well imaged, allowing the mine planners to optimize the mine design and layout. Current interpretation work is focused on enhancing the accuracy of these geological model seven further through the analysis of ?seismic trace attributes.? Preliminary testing on the Impala Platinum 3-D seismic volume has shown that attribute analysis has the potential to illuminate a number of geological reef disturbances that are otherwise ?invisible? in the original seismic time volume. Potential areas of improvement include inter alia: ?Improved definition of major fault zones ?Improved definition of zones of reef depression (?slumping?) ?Identification of reef terracing and/or reverse dip.. Keywords: 3D reflection seismics; Impala Platinum Ltd; seismic attribute analysis; Seismic Micro Technology (SMT); rock solid attributes; dip-azimuth; instantaneous phase and similarity.

Jan 1, 2004

By P Cochrane

Our ability to generate information and transport it about the planet on super highways of optical fibre is about to change the way in which we communicate, work and live. There is not a single aspect of our future that will go untouched by the communication and computing revolution that Is now upon us. The change we are about to witness will overshadow the impact of the printed word, industrial revolution and physical transport. The next major wave of information technology (TT) development will focus on the delivery of information and experience on demand, in the right form, at the right time, at the right price, to fixed or mobile terminals anywhere, over networks of optical fibre, radio, satellite and optical wireless. Bandwidth, distance and time will no longer be significant cost elements as service and access become dominant.

Jan 7, 1996

By Kristian E. Waters, Hao Ma, Haibei Wang

Heavy metal ions exist in waste effluents including mining tailings, manufacturing discharges, and smelting and metal plating process wastes. Various methods are available to treat industrial effluents containing high levels of metal ions, but when confronted with wastewater that has low metal ion concentration below 500 mg/L, most techniques suffer from low removal or separation efficiency as well as high operating cost. ELM-based techniques can be used to solve these problems.

Apr 1, 2023

By Howard I. Young

WHEN so many statements are being made relative to the requirements of zinc metal, it is difficult for some of us who are acquainted with the industry to visualize how it is possible to step up production so as to supply some of the fantastic requirement figures that are published from time to time. I shall attempt to approach this subject from the standpoint of existing conditions which affect production, also keeping in mind the price ceiling under which the industry operates. Total production of primary and secondary zinc in the United States for 1941 will be about 878,000 tons, to which should be added about 36,000 tons of Mexican slab zinc available for consumption or export from the United States, giving a total available of 914,000 tons. Production of slab zinc of all grades in 1942 should be 953,000 tons. Adding the available Mexican supply should bring the total to 989,000 tons.

Jan 1, 1942

By Israel Liebman

The Bureau of Mines developed three types of passive water barriers for suppressing slow-moving coal dust explosions. One type is a modification of a conventional tub barrier and depends on the dynamic pressure generated ahead of an explosion to tilt the tub to release its water and suppress the explosion. The other two barriers operate in response to an increase in static pressure developed ahead of the explosion. Tests indicate the first barrier begins to release its water at air speeds as low as 50 ft/sec, and the second and third barriers will operate at a rise in static pressure as little as 0.5 psi. All three barriers were found to be effective in suppressing coal dust explosions propagating at speeds as low as 100 ft/sec. A plan is described for installing a water barrier in a working mine on a trial basis.

Jan 1, 1976