Thesis--Wisconsin. / Vita. Includes bibliographical references (leaves 164-167).

The future of coal mining in the Witbank Coalfield over the next 30 years and beyond depends on effective and responsible utilization of the remaining reserves, both within unmined and previously mined areas. Similar to all mineral resources, coal is also non-renewable and the current resources will not last forever. Unlike most other resources coal resources have to be considered in long term strategic planning for energy supply. It has therefore become very important to use the remaining resources and reserves to their full potential. This has prompted mining companies to re-mine or do secondary extraction of areas mined during the previous 50 years. Reliable and internationally accepted valuation techniques and reporting standards are well established for virgin areas. The challenge is now to develop an equally robust and reliable system for remaining resources and reserves in previously mined areas. A number of established operations already exist in South Africa and internationally which are utilizing such reserves. Due to numerous factors affecting the viability of this type of operation a system or matrix is proposed for defining such resources and reserves. This classification scheme caters for the obvious geological, mining and beneficiation factors, and also for the multitude of lesser known but equally important factors. The effects of some of these factors on a future mining operation are demonstrated in a case study of such a previously mined area. Factors affecting the Run of Mine (ROM) tons and saleable tons are: a) derating percentage b) percentage mining extraction c) percentage dilution and contamination d) percentage fines generated e) spontaneous combustion Numerous pitfalls are identified such as top coaled areas, water accumulations, no access to old areas to verify existing information and the time lapsed since previous mining occurred. Another complicating factor is the lack of a method for the quantification of the impact of spontaneous combustion on remaining reserves. The financial viability of mining these areas are especially sensitive to the coal price, R/$ exchange rate, change in production and capital expenditure. The information generated during the investigation is processed in a financial model which is used to evaluate different scenarios and risk sensitivities. It is demonstrated that in evaluating previously mined areas, it is not the obvious factors that often determine the financial viability of a project, but rather the not so obvious financial factors. / Dissertation (MSc (Geology))--University of Pretoria, 2008. / Geology / unrestricted

Thesis (Ph. D.)--Virginia Polytechnic Institute and State University, 1999. / Paper copy printed by UMI (University Microfilms International), 1999. Includes bibliographical references (p. 94-99). Original electronic version available via Internet.

Thesis (Ph. D.)--Virginia Polytechnic Institute and State University, 1999. / Includes bibliographical references (p. 94-99). Original electronic version available via Internet.

Thesis (Ph. D.)--Universität Zürich. / Includes bibliographical references (p. 12-14).

Coal mining and timber are the two primary industries supporting the people of Southwest Virginia. Coal mining has occurred for more than 100 years, but production has dropped since reaching a peak in 1990. In order to properly plan with remaining coal production a study was conducted to characterize and estimate coal resources. Seam thickness was found to be the parameter which most influenced resource levels. An economic model was developed to determine which portion of the reserves could economically be extracted. It was found that 3.95 billion tons, or 14% of the remaining resource, is economic under current mining conditions. More than 60% of these reserves, however, are in deep seams which require shafts to be constructed prior to initiation of mining. / Ph. D.

Thesis (M.S.)--West Virginia University, 2009. / Title from document title page. Document formatted into pages; contains viii, 81 p. : ill. (some col.), col. maps. Includes abstract. Includes bibliographical references (p. 61-62).

This study attempts to provide detailed analysis of materials gathered from various sources and to an orderly presentation of facts and figures regarding railway construction in China.

A typical coal resource characterization study calls for estimating thickness, density, and quality parameters over a block or node simultaneously. Traditionally, estimation has been done for each variable independent of the other variables. The methods range from the well known polygonal and distance weighting methods to the geostatistical method of kriging. None of these methods takes the correlations between the variables into account explicitly. A comprehensive study has been undertaken to determine whether the joint estimation technique of cokriging may be used to utilize intervariable correlations in increasing the accuracy of estimation. Seam thickness, density, ash, calorific value, and sulphur have been studied to determine whether they are cross-correlated. Significant cross-correlations have been found to exist between ash content, density, and calorific value, where the rank of the coal is stable. A survey and a case study indicated that seam thickness may also be cross-correlated with ash content and density. Subsequently, separate kriging and cokriging results have been subjected to comparison via a cross-validation procedure. After normalization, cokriging has provided substantial improvements over kriging in estimating thickness, density, and ash content. Moreover, cokriging performed well in replicating the correlation schemes where kriging occasionally failed. In this study, geostatistical methods have been found to produce results in compliance with their probabilistic premises. A general purpose geostatistics software package has been written to carry out modeling and part of the research on a personal computer. This package has been designed to provide many advantages over the existing costly and black-box type software. / Ph. D.

Financial support given by the U.S. Energy Research and Development Administration and the Council on Wage and Price Stability.