Rajpur Dariba Mine

The lead-zinc ore body was being worked by the Vertical Retreat Method. Fifteen stopes had already been mined and packed with consolidated fill containing 5% cement. While stope T -17 was being filled, the cement plug at the drawal level gave way and about 8000 m3 of the slurry, together with broken pieces of the plug, flowed to the lower levels and the main shaft. The 6 m diameter main shaft was being deepened and a plug made of 1200 mm and 800 mm I-section girders overlain by a 25 mm thick steel plate separated the working portion of the shaft from the portion being deepened. The impact of the flowing material falling into the shaft was so great that the girders comprising the shaft plug got sheared and bent and the plug was completely damaged. The slurry fell down to the bottom of the shaft filling it up to 52 m from the bottom. Twelve persons at the shaft bottom engaged in deepening operations and one person at the drawal level were entombed in the slurry.