Field Evaluation of Stemming Plugs in Limestone Mining

Effective stemming is a critical yet frequently underestimated factor governing the utilisation of explosive energy in bench blasting. This paper reports the results of controlled field trials conducted at the Sitapuram Limestone Mine, the captive quarry of Zuari Cement Limited, located in Chintalapalem Mandal, Suryapet District, Telangana, India. Stemming plugs were deployed in half of a 29-hole blast to quantify their effect on rock fragmentation quality, muckpile throw, and per-tonne blasting cost relative to conventionally stemmed holes. The blast design comprised a staggered two-row pattern with 150 mm diameter holes, 8.5 m depth, 4 m burden, 5.5 m spacing, and ANFO as the primary blasting agent. Results indicate measurably improved fragmentation and greater muckpile displacement in the stemming-plug-assisted portion of the face. A preliminary cost comparison is presented. The findings corroborate the growing body of literature demonstrating that stemming plugs, by generating an air deck and reflecting a tensile stress wave within the borehole column, significantly enhance the efficiency of explosive energy utilisation without increasing drilling or explosives expenditure.

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