Flyrocks – Detection and Mitigation at Construction Site in Blasting Operation

Abstract

Construction and mining industry spends heavy coins on blasting technology, explosives and their safe detona- tion, from India's perspective safe blasting holds even more important stand. In India, around 90% of production comes from surface mines. In any surface mine, blasting is a crucial operation. Explosives in large quantities has been used for fragmentation of rock in surface mines but only a part of the explosive energy has been used in doing the useful work, the rest has been consumed toward unwanted work such as ground vibration, fly rocks, noise and air blast. These blasting prac- tices provide quick, efficient and cheap over-burden removal compared to other processes. However, they are major sources of mine related injuries and accidents. Usually blasting related injuries are related to fly rocks, lack of blast area security, premature blast and misfire. Out of these, fly rocks and lack of security accounts for 68% of total injuries incurred by blasting practices. The blasting is required for fragmentation and displacement of the broken rock. Fragmented rock is not expected to travel beyond the limit of blast area or the desired throw. However, sometimes they do. These rocks travel- ling beyond blast area or the throw due to force of explosion is known as fly rock. As fly rock is a critical issue in mining and construction industry, hence it becomes more so important to learn the causes for generation of flyrock and the mitiga- tion measures. This paper deals with causes of fly rock, hazards associated with flyrock and precautions to be taken to con- trol them with the help of a case study at a construction site. The Flyrock accident can be averted by sticking to basic prin- ciples of primary as well as secondary blasting. The shock tube initiation system may be preferred over detonating cord. Further, supervision of blast hole charging should get high order preference and care.