M. S.

The purpose of this investigation was to determine the effectiveness of the leaching streams from waste copper ore dumps as a nutrient solution for subsequent biological oxidation and solubilization of sulfide minerals. The copper in the leaching streams is precipitated by displacement with iron. As a result of this procedure the solution is high in ferrous iron concentration and has a pH of near 3.7. The bacteria in the leaching streams are capable of oxidizing ferrous iron to the ferric state and sulfide minerals to sulfates. The effects of temperatures, pH, urea, and aeration rate on the oxidation of the ferrous iron in the stream were studied. The effect of oxidized and reduced forms of the solutions, pyrite, urea, and pH on the solubilization of chalcopyrite were investigated. It was found that an increase in the rate of bubbling air through the ferrous solutions greatly increased the rate of oxidation of the solution. The optimum pH was found to be near 3.2. The optimum temperature was near 35°C. Added urea had little effect on the rate of oxidation of the ferrous solution. The presence of pyrite slowed the rate of solubilization of chalcopyrite. This was interpreted as being due to the lower pH caused by the oxidation of pyrite. Copper was found in the effluent leachates from the mineral samples when the pH was near 3.0. Little copper was found when the pH was below 2.5. Raising the pH with CaCO3 increased the rate of solubilization of chalcopyrite. Added urea had little effect on the rate. It was concluded that the reduced form of the leaching stream is an effective leaching fluid for the biological solubilization of chalcopyrite because of its relatively high pH and nutrient content. Pyrite is preferentially oxidized in the presence of chalcopyrite in tailing solution.

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This dissertation is a study of the development of property rights in the coal industry as defined by Federal legislation. Previous analyses have argued that property rights develop efficiently and have employed a neoclassical model to study this development in the political market. This study asserts that the neoclassical model is inappropriate for analyzing the political market. This study concentrates on the coal industry, analyzing the historical events surrounding development of the property rights structure. A price theoretic approach is employed to determine whether changes in the property rights structure results in greater efficiency for the coal industry. The evidence provided in the study does not support use of the neoclassical model. The model is too constrained and does not allow the inclusion of nonmarket factors in the analysis. / Ph. D.

M.S.

The Appalachian coal fields contain many contiguously placed seams of coal. Mining in these seams has been active over such an extended period of time that considerable knowledge has been gained in the area of multiple seam mining. It is commonly accepted that the preferred sequence of extracting contiguous seams is in descending order. However, in the past, selection of the mining sequence has been based primarily on seam ownership, availability and economics, not on ground control considerations. One of the major ground control mechanisms that must be considered in mine design, when contiguous seams have not been extracted in descending order, is subsidence. This investigation examines the affects of subsidence not on the surface but on mineable seams of coal lying above the seam that has been extracted. Case studies were collected from the Appalachian region. These studies were analyzed to determine which factors could be correlated with damage. An empirical model was then developed to predict when interaction problems caused by subsidence will noticeably effect mining in an upper seam. / M.S.

"Factors Which Affect Mining of the Lower Mississippian Coals in Montgomery County, Virginia" ie a study ot the Merrimac and Langhorne seams of the Price formation in Montgomery County, Virginia. The main reference used in the review of literature was Bulletin XXV of the Virginia Geolog1cal Survey by Marius R. Campbell. The review of literature discusses geologic formations and structure and the coal as seen in various prospect and mine openinga by Campbell. The author visited mines during the field investigation and analyzed samples of coal collected at the mines. He discusses past mining operations in Montgomery County and has traced all available mine maps of past mining operations. These are filed as part of the thesis. Core drillings were also investigated by the author and reported depths of the coal in the Blacksburg syncline ere entered in Table III and Figure I. An investigation was also made into mining methods used in Montgomery County including a discussion of explosive gases encountered in mining the Merrimac seam. The author discusses the results of the investigation in the conclusions. Be ia convinced the coals of the Valley fields, although of poor quality, will becane increasingly valuable as anthracite deposit in Pennsylvania and bituminous deposits in Southern West Virginia and southwest Virginia are depleted. / Master of Science