The implementation of subterranean barriers with mine pre-drainage to reduce coal mine methane emissions from open-cut and underground metallurgical-coal mines

Abstract

There is an opportunity to reduce methane emissions from Australian, open pit, metallurgical coal (MC) mines and substantially reduce the carbon intensity of a high-value Australian export industry. MC is critical to the production of steel products and is essential to meet international urbanisation and energy system transformation goals. Initial research on this topic, outlined the application of subterranean barriers in coal mining towards the reduction of gas influx and whole-of-life coal mine methane (CMM) emissions in underground applications. Initially, the technology lacked economic viability for a majority of cases and especially after carbon pricing was eliminated in 2014. Today, with the imperative for the industry to reduce emissions, the technology becomes significant in its potential for emissions reduction for both underground and open-cut coal mines.The basis of barriers is similar to naturally occurring barriers (i.e., igneous intrusions or dikes) that have shown effective separation of drained and undrained mine works (as observed in adjoining mines in Central Queensland). Barriers have also been applied in the environmental, civil engineering and oil and gas industries, to manage or restrict subterranean flow patterns or contain contaminants. In this case, subterranean barriers are being implemented in conjunction with mine pre-drainage to reduce methane emissions from an open pit, MC mine. In addition, barriers can be used in underground mining operations.to improve mine pre-drainage and safety as well as reduce methane emissions.This paper describes the design, execution, and evaluation workflows and the relative importance of variables required for a barrier implementation in subterranean applications for open-cut and underground mining applications. This paper details the results of ongoing planning and modelling to implement and assess a barrier application for reducing gas migration from unmined in-seam or underground mine sections into open-cut MC mining operations. Finally, this paper builds on previous research and available technologies and is complementary to current pre-drainage for surface or underground mining operations. Barrier implementation in conjunction with the beneficial use of gas provides a working framework to reduce mine emissions toward necessary methane reductions by 2030.