Semester

Summer

Date of Graduation

2014

Document Type

Dissertation

Degree Type

PhD

College

Statler College of Engineering and Mineral Resources

Department

Mining Engineering

Committee Chair

Yi Luo

Committee Co-Chair

Christopher Bise

Committee Member

Felicia Feng

Committee Member

Jingxin Wang

Committee Member

Liming Yuan

Abstract

Spontaneous combustion is one of the most serious problems to mine safety and production in the global coal industry. It is considered to be the trigger for fires and explosions in underground coal mines especially for gassy mines. Such thermal events are not easily detectable since they normally occur in inaccessible gob and sealed area. It is also difficult to find the most likely hot point accurately. Admittedly, determination of the propensity for spontaneous combustion before mining activity should be a necessary step in the design of a mine and ventilation plan. However, due to the complexity of the chemical and physical properties of coal, spontaneous combustion has not been fully understood.;Many methods and techniques have been developed for studying self-heating of coal. Each of the methods has its unique characteristics and index for assessing the propensity of self-ignition. However, all the reasonable candidate factors causing spontaneous combustion could not be examined thoroughly by any single method. Accountable relationships among the propensity indices of different methods should be established. The certainty for assessing the propensity of spontaneous combustion will be greatly improved by using the combination of various methods. On the other hand, spontaneous combustion is affected by many factors. According to a proximate analysis of coal, it is believed that sulfur and volatile matter in coal are the main intrinsic factors that cause the self-heating of coal. Their oxidation at lower temperatures than that of fixed carbon to initiate coal's self-heating should be quantified.;In order for better understanding spontaneous combustion behavior, the following research has been done in this dissertation:;• Establishment of a coal spontaneous combustion testing facility that features adiabatic self-heating, thermogravimetric analyzer (TGA) and USBM self-heating temperature methods in the mine ventilation laboratory at West Virginia University.;• Correlation of U.S. coal rank and propensity for spontaneous combustion has been studied by classifying coal rank quantitatively. This quantified rank system provides a schematic view that reflects the relationship between rank and self-heating temperature of coal. As such, it can be used to serve as a quick estimate of self-heating potential of U.S. coals and as a cost effective way for initial risk assessment for any new mine development.;• Based on the law of energy conservation, a mathematical model has been developed to quantify the self-heating rate of coal and assist the adiabatic self-heating test when the testing period becomes impractically long. Then improvements have been made to the model by enhancing the model's ability to consider the effects of sulfur, volatile matter and moisture contents in the coal - three important factors affecting a coal's self-heating process. Heat release rates for pyrite oxidation and moisture condensation are built into the model.

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