Development of an Assessment Tool to Minimize Safe after Blast Re-Entry Time to Improve the Mining Cycle


A study has been examining the present problems resulting from inappropriate re-entry times across Australian underground development heading mining practices. It has focused on possible solutions that enable current ventilation practices with reduced quantities of fresh air without affecting re-entry times, or shorter re-entry times without increasing fresh air requirements or a combination of both. After blast re-entry times have been identified as a potential safety problems exaggerated by advanced mining technology and complicated by the modern prevalence of 12 hour shifts. Industry surveys on blasting re-entry time indicate most mines rely on a fixed time strategy to deal with the after blast re-entry mostly based on past experiences and observation. Very few monitor blast fumes for gas composition. A series of measurements of after blast fumes in various development heading arrangements has be undertaken to improve the understanding of occurrence and magnitude of blast contaminants. A development face ventilation study has been undertaken. Rigorous analysis has produced two empirical equations that can be used with some confidence to conservatively estimate re-entry times for level development headings. It was concluded that the working space volume used in mathematical modeling might be a constant for development headings of a similar configuration and environment, regardless of the relative distance from the end of the ventilation ducting to the face. Further testing is required to confirm this hypothesis.

Meeting Name

10th U.S./North American Mine Ventilation Symposium (2004: May 16-19, Anchorage, AK)


Mining Engineering

Keywords and Phrases

Blasting Re-Entry Time; Fresh Air Requirements; Ventilation Practices

Document Type

Article - Conference proceedings

Document Version


File Type





© 2004 A. A. Balkema, All rights reserved.

Publication Date

19 May 2004

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