976 resultados para Underground Mine


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This paper investigates the composition of remuneration packages for middle managers and relates the structure of remuneration contracts to firm-specific attributes. A statutorily defined position in a single industry is studied as an example of middle management. This allows us to control for differences in task complexity across managers and industry-induced factors that could determine differences in remuneration contracts. Higher-risk firms are expected to pay their mine managers a greater proportion of variable salaries and market and/or accounting-based compensation than low-risk firms. Results indicate that high-risk firms pay a higher proportion of variable salaries and more compensation based on market and/or accounting performance.

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Velocity and absorption tomograms are the two most common forms of presentation of radar tomographic data. However, mining personnel, geophysicists included, are often unfamiliar with radar velocity and absorption. In this paper, general formulae are introduced, relating velocity and attenuation coefficient to conductivity and dielectric constant. The formulae are valid for lossy media as well as high-resistivity materials. The transformation of velocity and absorption to conductivity and dielectric constant is illustrated via application of the formulae to radar tomograms from the Hellyer zinc-lead-silver mine, Tasmania, Australia. The resulting conductivity and dielectric constant tomograms constructed at Hellyer demonstrated the potential of radar tomography to delineate sulphide ore zones. (C) 2001 Elsevier Science B.V. All rights reserved.

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Pasminco Century Mine has developed a geophysical logging system to provide new data for ore mining/grade control and the generation of Short Term Models for mine planning. Previous work indicated the applicability of petrophysical logging for lithology prediction, however, the automation of the method was not considered reliable enough for the development of a mining model. A test survey was undertaken using two diamond drilled control holes and eight percussion holes. All holes were logged with natural gamma, magnetic susceptibility and density. Calibration of the LogTrans auto-interpretation software using only natural gamma and magnetic susceptibility indicated that both lithology and stratigraphy could be predicted. Development of a capability to enforce stratigraphic order within LogTrans increased the reliability and accuracy of interpretations. After the completion of a feasibility program, Century Mine has invested in a dedicated logging vehicle to log blast holes as well as for use in in-fill drilling programs. Future refinement of the system may lead to the development of GPS controlled excavators for mining ore.