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By David E. Thompson, Andrew F. McKown, Herbert H. Einstein, Amr S. Azzouz

INTRODUCTION Design of supports for underground chambers in rock has undergone considerable development. This becomes evident when comparing support dimensions of subway station caverns built in the U.S. over the past fifteen years. The Porter Square Station cavern, which is a part of the Massachusetts Bay Transportation Authority (MBTA) Red Line extension, is the latest in this series. It is approximately 168 m (550 ft) long, 21 m (70 ft) wide, and 14 m (45 ft) high, and has a permanent support of light steel ribs imbedded in a 0.4 m nominal (15 in) shotcrete lining. An extensive construction control instrumentation program made it possible to evaluate the performance of the cavern and its support. This evaluation, which is presented in this paper, was the objective of a research project sponsored by the Urban Mass Transportation Administration (UMTA) and jointly conducted by Haley and Aldrich, and MIT. The actually used design procedure was compared with other approaches, notably procedures based on Finite Element analyses and empirical rock mass classification methods. Support dimensions predicted with all these approaches were compared to the actual support and its performance.

Jan 1, 1983

By R. Kwiatkowski

Agenda ? Health Canada Protocol _ Screening Level Risk Assessments (SLRAs) Contaminants Foods Exposure Pathways COPCs _ Site Specific Risk Assessments (SSRAs) In-depth, quantitative Monitoring Exposure estimates Food Issues in Environmental Impact Assessments ?Country Foods? ? Foods gathered from the project area and consumed by local residents.

Apr 1, 2005

By A. C. Fieldner

IN the Wall Street journal for March 1, 1941, was a tabulation of the construction under way or under negotiation by thirteen iron and steel companies for a predicted increase in annual coke production of 3,165,600 tons. That even this figure was short of the mark is indicated by other plans, then being considered, for a later expansion of 2,610,000 tons additional. Considerable progress has already been made on thin program, for approximately 500 new ovens were put in operation in 1941. and well over 200 should be completed in 1942. These figures include a number of units that replace older and obsolete equipment.

Jan 1, 1942

By D. M. Davidson, P. F. Kerr

The Permian Cutler Formation in Kane Creek, Utah bears uranium ore in fissure-type vertical veins. This fissure vein formation and its associated host rock bleaching, weak argillic alteration, and base-metal sulfide mineralization along with the development of hydrothermal minerals, a 60 m.y. isotopic Pb/U age, and well-crystallized uraninite's structural control, give evidence of ore deposition in a hydrothermal environment consistent with Laramide mineralization. Mica polymorph studies indicate first, that temperature during the hydrothermal alteration or subsequent ore deposition did not exceed 200°; hence Cutler deposits are classified telethermal; and secondly, that rock alteration and ore deposition are closely related both in time and space, as is seen in argillic alteration sequence. Ore deposition in an alkaline to slightly acid reducing environment is postulated. Ore textures and mineral associations and distributions also indicate that carbonate complexes may have been transported with the deposing ores. Bleached rock formations are not primary strati-graphic phenomena. Bleaching, or changes in ferric iron content, results from a chemical process involving reduction and conversion of hematite to a soluble aqueous ion. Nearby Chinle bedded deposits (Moss Rack sandstone), containing shale lenses, fossil wood, organic debris and minor fractures, overly the Cutler formation. Chinle ores have a single reported isotopic age of approximately 200 m.y. Their chemical environment is assumed similar to that of the Cutler ores, though slightly more acidic. Two genetic, paradoxically divergent interpretations of the bedded deposits are derived from available spectrographic, petrographic, X-ray and chemical analyses. Kane Springs canyon is located southwest of Moab, Utah, south of the Colorado River and northwest of the Lisbon Valley mining district (Fig. 1). Uranium deposits occur along the northeast flank of a Kane Creek salt anticline where two geologic formations bear ore, the Permian Cutler and the Triassic Chinle. The Cutler deposits' fissure vein formation is an unusual occurrence in the Colorado Plateau. The Chinle deposits appear to be of the normal sedimentary type. Associated with the vein deposits are a number of features, including argillic alteration of sedimentary strata. The minerals of these deposits and their associated features have been studied in detail in a two year program entailing both field and laboratory techniques. STRATIGRAPHY A stratigraphic section of the lithologic units in the Kane Creek area is given in Table I.

Jan 1, 1967

By D. Chetty

Process mineralogy forms an integral part of geometallurgy, with ore body characterisation being but one piece of the puzzle in optimising value derived from ore. This value is not only financial, but importantly speaks to sustainability from environmental and social standpoints. The reactive approach of traditional process mineralogy is increasingly being replaced by predictive methods in the geometallurgical sphere, for which mineralogical information must be timeously acquired on judiciously selected sample sets to understand ore variability and its impact on orebody processing. Such processes are not only metallurgical, but must incorporate mining and waste management protocols. Dwindling resources like water and energy also demand innovative approaches for lowering consumption and/or promoting recycling along the value chain. Addressing such challenges relies on appropriate characterisation of ore behaviour under different process regimes. Coupled with this, emerging characterisation tools are increasingly applied to understand the mineralogy of unconventionallypresented and difficult-to-process ores to meet societal and technology demands. Such tools are often accompanied by the generation of large, computationally intensive datasets, for which data management and storage are key requirements, particularly when deciphering temporal trends in ore and process variability. This paper will elaborate on these themes with examples that highlight the importance of process mineralogy throughout the minerals value chain. Keywords: Process mineralogy, ore characterisation, geometallurgy

Jan 1, 2020

By K. K. Kershner

The purpose of this investigation was to develop methods, on a laboratory scale, for recovering tin from Bolivian metallurgical slimes. Petrographic and chemical analyses were made of slime ore fractions from several well-known tin operations. High percentages of the total tin were volatilized as chlorides at temperatures below 600° C. Under optimum conditions reaction rates were relatively rapid, and the chloridizing reaction approached completion. Owing to the low temperatures involved and the high yields of tin, the process was considered to have possibilities for treating Bolivian slimes on a commercial basis. ACKNOWLEDGMENTS Appreciation is hereby extended to the Patino Mines and Enterprises, Inc., of Bolivia, for supplying slimed tin ores that were used in the experimental work. This company has since been nationalized.

Jan 1, 1959

By Jan A. Nilsen

This paper describes a key element in the construction of a major project undertaken by Harbourfront Corporation in its efforts to rejuvenate the central Toronto waterfront. The Spadina Pier forms one of the two major structures of the $10 million marina complex. Completed in early 1986, the 150 metre(490 ft.) long by 43 metre(140 ft.) wide pier structure will contain a 320 car parking garage as well as providing the foundation of a 17-story residential tower and a two-story retail/commercial complex. However, the pier structure posed a considerable challenge to its developers due to the the many restrictions imposed on the site by the environmental authorities which ruled out the construction of dykes or the placing of other fill materials on the highly contaminated bottom sediments. In addition, access at the site was restricted by its proximity to the main harbour navigation channel and a grain elevator berth. The original design called for a cofferdam to form an integral part of the finished structure. However, the contractor chose to regard the cofferdam as a temporary structure and proposed to construct the pier in the dry by enclosing the 10,000 square metre(107,600 sf) site with a 450 metre(1480 ft.) long single wall steel sheet pile cofferdom 7.5 metres(25 ft.) from the final pier structure. This paper will describes the design and construction of the cofferdam. Prior to finalizing the pier design, a geotechnical investigation of the shale bedrock was undertaken as well as a small sheet pile test cell program to evaluate the feasibility of driving a Canadian manufactured cold-rolled sheet pile into the bedrock. Relying on the design parameters for the shale bedrock, Foundation designed the cofferdam utilizing a post-tensioned bipod bracing system to resist a 7 metre(23 ft.) hydrostatic head as well as the maximum wind and wave forces expected at the site. The bipod bracing system consists of diagonal H-pile raker piles and verticle pipe piles anchored to bedrock with post-tensioned anchors grouted into bedrock.

Jan 1, 1987

By Weslei Viana Gabriel

Por meio do uso de técnicas de modelamento físico e matemático, caracterizou-se o fluxo de líquido, no interior de um molde de beam blank, quando alimentado por apenas uma válvula submersa constituída por três portas de saída cilíndricas e espaçadas de 120°. Verificou-se que o fluxo do jato de líquido que atravessa a alma se espalha ao longo de toda a superfície do flange antes de se recircular na região central do molde. Através da técnica de injeção de traçador e análise do perfil de velocidade, percebe-se que os jatos direcionados para as quinas do flange recirculam rapidamente e, por isto, se espalham numa pequena região. Este tipo de válvula se caracteriza também por ter uma maior intensidade de oscilação da superfície do que a válvula do tipo tubular. Foram realizados testes para simular a taxa de remoção de inclusões. Os dados obtidos mostram que esta válvula é mais eficiente na limpidez do aço do que uma válvula tubular simples.

Oct 30, 2017

By M. K. Elmouttie, G. V. Poropat

The analysis of structure using joint set statistics is well known. Other data such as the position of discontinuities and the contacts between rock mass units cannot be easily incorporated in simple statistical analysis based on orientation alone. Algorithms to model the structure of rock slopes using measurements of the orientation and position of discontinuities are being developed by CSIRO Exploration and Mining. These algorithms provide a capability to model the structure of a rock slope and estimate the likelihood of the formation of hazardous blocks in existing or proposed rock slopes and identification of the location and size of these blocks. The algorithms provide the basis of structural modelling to identify potential failure mechanisms in rock slopes.

Jan 1, 2006

By M. van Schoor

The bulk of the world?s platinum production originates from the Merensky and UG2 reefs within the Bushveld Complex, South Africa. Both the Merensky and UG2 reefs are disrupted by faults, dykes, potholes and iron-rich ultramafic pegmatite bodies (IRUPs)?features that impact negatively on production, planning and safety. It is therefore advantageous to know of their presence and geometry ahead of mining. To date, no geophysical technique has been successfully applied to the routine mapping of mine-scale potholes and IRUPs. These disruptive features may vary from a few metres to several tens of metres in diameter. In this paper the applicability of in-mine electrical resistance tomography (ERT) to map potholes and other disruptions to the continuity of the Merensky and UG2 reefs ahead of mining is demonstrated using two case studies.

Jan 1, 2005

By Izabela Diniz Duarte

O controle da temperatura do aço líquido desde o refino secundário até o lingotamento é condição essencial para alcançar alto nível de qualidade do produto final e economia de energia, o que permite ressaltar a importância de se determinar as perdas térmicas na panela. Entre outros fatores este trabalho buscou identificar a importância relativa das perdas térmicas para o revestimento refratário e através da escória. A temperatura, espessura da camada de escória, temperatura do revestimento refratário, propriedades físicas e características de convecção foram os fatores considerados. Cálculos numéricos que quantificam essas perdas.

Jul 30, 2018

By Renzon Daniel Cosme Pecho

O consumo do carvão mineral no mundo se encontra em aumento nos últimos anos, devido ao aumento dos preços dos combustíveis fósseis. No caso do Brasil, o carvão mineral é de baixa qualidade contendo, por exemplo, elevado teor de cinzas. Desta forma, o beneficiamento do carvão mineral gera uma quantidade grande de rejeito (RJ) que em contato com a água da chuva é responsável pela conhecida formação da drenagem acido. Alguns trabalhos vêm sendo propostos para contornar este inconveniente, alguns voltados para o aproveitamento do enxofre contido, outros pensando na geração de um possível condicionador de solos ou ainda na obtenção de absorventes para tratamento de efluentes. Dentro deste contexto, o presente trabalho estuda uma possível utilização do rejeito de carvão mineral do sul de Brasil através da extração de Ácido Húmico (AH) e a subsequente utilização deste no tratamento de efluentes. O trabalho reporta o uso da eletrooxidação do RJ seguido da caracterização do AH obtido por analise elementar e espectroscopia de 13C RMN CP/MAS. A etapa de aplicação do AH foi conduzida através de uma avaliação sobre a remoção de Pb+2 contido em uma solução sintética. A extração do AH consumiu cerca dos 12% da massa do RJ e a sua caracterização indicou um componente aromático de 54%, seguido pelos grupos alifáticos (34%). A proporção de grupos contendo oxigênio foi relativamente da ordem de 6% de O-alquilo, 3% de COO- e 3% de C=O.

Aug 8, 2018

By James E. Harding

AT just about the geographical center of the peninsula of Lower California is the El Arco gold mine. It is small and spotty, and three separate attempts to operate it in the past have failed. The only reason the present operation is possible is because of the higher price of gold and because the previous operators had spent about $300,000 developing the property with shafts, four levels, machinery, and a complete mill, all of which was acquired at a bargain price. All the known ore in the mine, to say nothing of the cost of recovering it, is

Jan 1, 1937

By Steven D. Wirch

Abandoned underground coal mine areas must either be sealed or ventilated to comply with federal mine regulations. Ventilation of these abandoned areas is often impractical due to roof falls and inadequate primary mine ventilation. If the area is sealed, a very complex ventilation system is set up. In which the gob "breathes" in and out due to barometric pressure fluctuations. The Gob Assistant is a computer program (for use on IBM compatible personal computers) which allows the prediction of air flows into and out of a sealed mine area. Gas flows with applicable control techniques are also modeled. This information is presented to the user who will decide which control technique, or combination of techniques will ultimately be applied. The Gob Assistant is an intelligent gob simulator that can reduce the guesswork involved in predicting the effects of sealing and control techniques before they are applied. This paper provides the fundamental principles upon which the Gob Assistant is based, verification of these principles, and an explanation of how these principles were integrated into the Gob Assistant.

Jan 1, 1988

By B. C. Vargas

The Toulon tunnel project is a key component of the Highway corridor on the French Riviera between Marseille and Nice and is a fundamental transportation infrastructure for the region. The first design studies started in the 1960?s. The tunnel project is made of 2 separate tunnels: South and North tunnel. The North tunnel was built between 1992 and 2002 after 10 years of difficult construction (for example, on March 15th, 1996, a collapse of the tunnel in the ?Marchand Area? generated a sink hole in the city Center, causing 20 months delay). The South tunnel alignment runs parallel to the North tunnel at the same depth below Toulon historical downtown (20 to 40m depth with some areas with less than 10m of cover). The Risk management program was studied to be a State of the Art program in urban tunneling construction. The Hydro Geological Context The whole project area is covered with backfills and colluviums of 1 to 4m thick. The Schist, marls and sandstones, randomly distributed along the alignment below the first layer have different characteristics. While the Schist are pretty compact, the marls are fractured. The other layers have very different characteristics, and many faults are located along the alignment, especially in the limestones. The Breccia are heavily decompressed and deformable, as well as the other soils located in the Marchand Area. This 80m long area is where the settlements need to be controlled with an extensive monitoring program. The complete Geological profile is presented in Figure 1. [ ]

Jan 1, 2012

By M. McWha

Laboratory bias is a universal problem in all branches of analytical science. It results from differences in methods, techniques, equipment, and calibrations between laboratories. Notwithstanding that it is a property that can be measured by the use of standards or by inter-laboratory testing, laboratory bias remains a material issue for the mining industry. There is extensive literature and clear guidelines on measurement from the International Organization for Standardization (ISO) and its worldwide federation of national standards bodies (ISO member bodies) and from the science of metrology. ISO guides cover the manufacture and use of standards. An accessible source of literature covering laboratory quality control comes from the public health sector, particularly pathology. There is little doubt in financial reporting rules about the meaning of materiality. Public reporting guidelines are clear that material matters need to be disclosed for investors. Unfortunately there is currently no clear guidance what to do about biased assay results in mineral industry public reporting guidelines. This paper reviews the requirements for the manufacture and use of reference materials, public reporting requirements in the mining industry, and presents proposals to improve management and reporting of laboratory biases. Keywords laboratory bias, reference materials, ISO Guides, financial reporting, materiality.

Jan 1, 2014

By H J. Stedman

A Transient Electromagnetic (TEM) geophysical survey was trialled in Bowen Basin Permian coal measures overprinted by Cretaceous intrusion. The trial’s intention was to compare whether TEM could assess residual coal more accurately and economically than drilling.TEM results were promising but had limitations. TEM did not compare to drilling for defining coal thickness or relative level definition. However, TEM resolved conductive anomalies laterally; providing a qualitative picture of remnant coal.Three material types and associated conductivities occur within the trial area: overburden (sandstone/siltstone), intrusive sills and heat affected coal.Ground conductivity was analysed by measuring decay of residual current within the TEM loop. Fast decay related to resistive overburden and intrusion, attenuated decay related to conductive coal.Generally speaking, carbon content governs coal resistivity where good quality, low ash, bright coal is more resistive relative to dull, high ash coal. Though in the trial area, relative to intrusion and overburden, coal was found to be the most conductive of the three materials.By modelling conductive anomalies, a general picture emerged of remnant coal regions. Subsequent highwall exposure reconciled with conductive TEM anomalies.CITATION:Stedman, H J, 2017. Findings from a transient electromagnetic trial for heat-affected coal, in Proceedings Tenth International Mining Geology Conference 2017, pp 233–238 (The Australasian Institute of Mining and Metallurgy: Melbourne).

Sep 20, 2017

The Federal Coal Mine Health and Safety Act of 1969 limits to 2 milligrams per cubic meter (for dust containing a maximum of 5% quartz) the average respirable dust concentration to which individual miners may be exposed. Section 205 of the Act directs that an appropriate exposure formula for dusts with quartz content in excess of 5% be established. This formula, entered in F. R. Document 70-12351 filed September 16, 1970, is 10 milligrams per cubic meter divided by % quartz. Thus, the total respirable dust exposure permitted limits the quartz to a maximum of 100 micrograms. For example, if % quartz is 5%, 10 mg/5 = 2 milligrams, and (.05) (2 mg) = 100 micrograms. Similarly, if % quartz is 10%, 10/10 = 1, and (.10) (1 mg) = 100 micrograms, etc. If the % quartz is less than 5%, the 2 mg/M3 limit prevails.

Jan 1, 1974

By Antonio Augusto Gorni

A Temperatura de Não-Recristalização (Tnr) é um parâmetro fundamental para a definição dos limites de temperatura a serem adotados nas fases de esboçamento, espera e acabamento da laminação controlada de chapas grossas feitas com aços microligados. Sua determinação experimental normalmente requer a execução de ensaios laboratoriais de torção a quente mas, a princípio, também é possível que a Tnr seja determinada a partir da evolução dos valores de tensão de escoamento média e temperatura obtidos durante a laminação de chapas grossas. O objetivo deste trabalho consistiu em verificar a viabilidade desta abordagem sob as condições específicas da usina de Cubatão da Usiminas. A partir dos resultados obtidos foi possível verificar o real potencial desta técnica, propor alterações na metodologia disponível na literatura e constatar suas limitações.

Jul 30, 2018

By Jian Li

Developing the Generation IV nuclear reactor is an international collaborative effort. One of the most promising Gen IV nuclear reactor designs is the supercritical water (SCW) concept, in which the water coolant runs at about 625 oC at the outlet. Under this temperature and high pressure condition, the cooling water is at supercritical state, which poses significant demand for both in-core and out of core materials. High-temperature mechanical properties, corrosion resistance and radiation damage are some of the key challenges. At present, no single commercial material can meet all the requirements of the severe SCWR conditions. Corrosion experiments per-formed under SCW condition yield various kind of corrosion modes, some are very challenging to characterize using conventional techniques. A combination of various advanced characterization techniques proofed to be essential to understand the root cause of materials? degradation.

Jan 1, 2010