Prevention of rock and gas outbursts in superdeep-level mining in Internatsionalny Mine of ALROSA

Abstract

Since 2019 development heading and construction of permanent roadways in Internatsionalny diamond mine of ALROSA below the absolute elevation of –790 m (depth 1190 m) is carried out in complicated geological and geotechnical conditions due to susceptibility of enclosing rock mass to rock and gas outbursting. The outbursting nature assessment and development of safe mining methods in such conditions were implemented in association with top academic institutions specializing in safe underground mineral mining under geodynamic hazard, namely, the Institute of Mining of the Ural Branch of the Russian Academy of Sciences, VostNII Research Center, VNIMI Research Institute, RMS Mining Solutions, etc. The main method to prevent gas dynamics phenomena is assumed as the controlled advance shooting in adjacent rock mass by means of drilling-and-blasting of rocks in front of a fore-breast to a depth of 1.7–2.5 m. The current outburst hazard prediction in dolomite rocks is implemented daily by measuring initial gas flow velocity in test holes with diameter of 43 mm using MIG-TS1 tool. For enhancing prediction efficiency, the optimized shooting chart design includes three operating stages: stage 1 is advance shooting to 6.5 m; stages 2 and 3 are blasting intended to advance the face by 2.2–2.5 m with regard to the assumed fragmentation factor. These measures enable an essential increase in the rate of heading and mining at the required level of safety.