Paste backfill responses in deep mine temperature conditions
9th International Symposium on Mining with Backfill
Mechanical stability, economical performance and environmental behaviour represent important performance criteria for a cemented paste backfill (CPB). During the last fifteen years several studies have been conducted to investigate the factors affecting these properties. However, until now, most of the studies were carried out on CPBs cured at “laboratory” curing temperatures (20-25°C). This means the deep mine temperature conditions were mostly ignored.
Recent explorative studies have revealed that the mine temperature affects significantly the strength and pore structure of CPB at early ages. However, these studies were only focussed on the short-term properties of CPB; moreover only limited CPB mixtures were tested. The economical performance and environmental behaviour were also not addressed. Thus, there is a lack of knowledge about the performance of CPB in deep mining environments. Furthermore, the progressive depletion of ore available at shallow depths in several underground mines worldwide means that underground mining operations occur more and more often at greater depths. Hence, an understanding of the effect of deep mine temperatures on the performance of a CPB is required for both economical and environmental reasons, and the safety of mine workers.
Hence, a research program was conducted to study the impact of deep mine temperature conditions on the short-term to long-term properties of CPB. Several CPBs with different compositions, cured at different temperatures (20 to 50°C) and times (7 to 150 days) were tested regarding their mechanical properties, economical performance and microstructural properties. The obtained results have shown that the mechanical, economical and microstructural (short-term to long term) performance of CPB is strongly influenced by the deep mine temperature conditions. This finding can potentially have serious backfill design implications in today’s and tomorrow’s mines. Results of this study could serve as background information for the development of optimal backfill design procedures in deep mine.
DEEP MINE, Safety, Performance, Paste backfill, economical, Stability