‘Mine-to-Close’ method best for managing mine-closure risks – Beale – by Dorothy Kosich (Mineweb.com – February 11, 2014)

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Heavy data gathering, lab testing instead of field tests, and standards-based regulation may not be the best approach to sustainable mine closure, says mining hydrologist Geoff Beale.

RENO (MINEWEB) – Mining hydrologist Geoff Beale of Schlumberger Water Services is urging mining companies to “take careful consideration of closure when planning their initial and expanded site layoffs” to reduce the chance of being saddled with mine pollution liability issues in perpetuity.

In a presentation to the Northern Nevada Section of the Society for Mining, Metallurgy and Exploration Monday night, Beale noted that mine operators increasingly adopt a “mine to close” approach when planning their initial and expanded site layouts.

Beale reminded his audience that the controlled mine closure has only occurred within the past two decades, and that many of the mines entering the closure stage now were developed before closure regulations existed.

Nevertheless, he stressed, it is best for miners to manage mine closure issues, rather than handing it over to government agencies, which immediately reduces efficiency and raises cost, such as can be the case with foreign governments of developing nations.

In his talk, Beale observed that mine closure practices and science address four general categories: 1) open pit mines in arid environments, such as those found in Nevada; 2) open pit mines in temperate/humid environments; 3) underground mines in elevated terrains; and 4) underground mines in lowland terrain. Beale called underground mines in lowland terrain the easiest to manage for closure, while underground mines in elevated terrain are the most difficult.

Issues which may have to be managed during mine closure include pit backfilling, rapid flooding to form a pit lake, managing pit slope instability on closure programs, and how to minimize the potential for acid generation and achieve acceptable post-mining water quality. The management of Acid Mine Drainage is often a primary obstacle for mine closure.

Ironically, the same sinkhole problems which plague Florida now have become a post-closure mine issue in South Africa, Beale observed.

While studies are important for developing broad closure concepts and for identifying crucial closure issues at the early stage of the mining cycle, Beale noted, “There will be a much greater understanding of actual closure conditions during the final years of mine operations when a longer period of monitoring data is available.

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