by Ashis Sinha
In the midst of the COVID pandemic’s social, economical, and psychological impacts, a team of mining engineers from IIT (ISM) Dhanbad conducted a study to investigate solutions to reduce the effects of blasting in mines, such as house collapse and habitat discomfort, produced by ground vibration.
The team comprises a PhD student of the Mining Engineering department, Anurag Agarwal, a native resident of Chhattisgarh who carried out the research under the guidance of his faculty members, including his research guide Dr. B.S. Choudhary and senior faculty Dr. VMSR Murthy, from March 2020 to December 2020 in the coal mines of Jharia, the dolomite stone mines of Gaya in Bihar, and the limestone mines of Rajasthan, proposed a blasting design that can help to reduce blasting-induced environmental issues, informed Rajni Singh, Dean Media and Branding, IIT (ISM).
In his nine-month survey and data analysis, Agarwal found out that the average percentage of explosive energy conversion into seismic energy is higher (6.12 per cent) in dolomite mines than in coal mines (around 3.1 per cent).
The analysis of blast vibrations, which was also performed with MATLAB, revealed that seismic energy dissipated into rock masses correlates with radial distance after using the modified seismic energy prediction equation.
“Explosives used in mines are primarily aimed at the fragmentation of rocks for mineral excavation, but despite significant technological development in this area, explosive utilisation efficiency has not been increased,” said Agarwal, adding that under current blasting practices, only less than 30% of explosive energy is used for breakage and displacement of rock masses in mines, while the remainder is wasted in unwanted effects such as ground vibration, fly rock or air overpressure, noise light etc.
Such unintended consequences of blasting frequently result in the relocation of people from mining areas, and sometimes law and order issues arise as a result of protests by blast victims. After conducting extensive research on mine blasting, Seismic energy prediction in bench blasting is the key to its optimization, so our study was conducted to predict the mine blast, induced seismic energy, which was analysed using Peak Particle Velocity (PPV),” added Agarwal.
A modified equation to predict the conversion of explosive energy into seismic energy has been proposed as part of the research, said Agarwal adding, “the blast design proposed as part of the research, as well as the modified equation, can aid in the optimization of seismic energy released during mine blasting.”