4 - Coal wastes: handling, pollution, impacts, and utilization

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Nearly 40% of the worldwide electricity generated comes from coal; therefore, coal will remain a crucial contributor to the global security of energy supply in the following decades. In the extraction of precious coal products, 1ton of hard coal produces 0.4tons of extractive waste materials, including coal washery rejects, tailings, and waste rock. The latter two often contain economically recoverable coal. There is an emerging demand for more responsible ways of disposing of mine waste and tailings because of many severe environmental impacts across the globe caused by coal-waste dumps and tailings storage facility failures, runoff water pollution, and spontaneous combustion incidents. One promising solution that has emerged is to seek revenue generation opportunities by creating secondary products from the waste streams. This can occur by recovering fine coal from a tailings stream and using the extra revenue toward the cost of a “dry” disposal solution. There is also potential to recover “lost coal” from plant discards either after placement in dumps or beforehand by additional crushing to liberate the saleable coal. In addition, opportunities such as the recovery of minerals, rare earth elements, and individual mineral concentrates should also be considered. Other potential secondary products include various low-cost building products, ranging from road base, fabricated bricks and blocks, roofing materials, and agricultural products such as soil additives and moisture-retaining materials offered in various pellet forms. This chapter focuses on the coal mining waste situation globally and describes efforts to reuse coal mining waste and recover lost coal. Case studies on a few recently completed projects are included at the end of this chapter. We thus concluded that it is vital to find new ways to manage, reuse, and recycle coal mining wastes due to unavoidable environmental issues.