Document Type

Conference Paper

Publication Date


Publication Details

Ashutosh Bhaskar, Alok Kumar Baranwal, Praveen Ranjan, Tapan Kumar Jena, Mayank Shekhar and Debaprasad Chakraborty, Application of plastic funnel in blast hole to improve blasting efficiency of opencast coal mine at West Bokaro, in Naj Aziz and Bob Kininmonth (eds.), Proceedings of the 2019 Coal Operators Conference, Mining Engineering, University of Wollongong, 18-20 February 2019, 345-351.


Blasting being one of the key activities of mining, its efficiency in terms of lower explosives consumption, improved rock fragmentation, decreased fly-rock, reduced noise and vibration level is very much desired for an effective mining operation which can be achieved by maximizing the utilization of explosive energy in the blast hole. Use of ‘reverse plastic funnel’ into the blast hole is one of the techniques for more utilization of explosives energy to improve blasting efficiency. The reverse plastic funnel is placed between explosive and stemming column in the blast hole which eliminates the contamination of explosive from drill cuttings (used for stemming), thus increases the Velocity of Detonation (VoD) of the explosive. Also, the conic shape of funnel creates a ‘Wedge effect’ guiding more of the explosive energy into the rock rather than upward out of the blast hole which helps in utilizing more explosive energy for rock breakage and reducing fly rock generation. In order to establish the benefit, trials were carried out in OB (overburden) benches of opencast coal mine at West Bokaro. In-hole VoD is measured by using Micro Trap VoD Recorder. It was found that the in-hole Velocity of Detonation (VoD) of the explosive is more in blast hole having funnel which means more strength of explosive. It was also observed that the fly rocks generation is negligible from blast holes in which funnels are placed.