The accident at the Mir mine on August 4, that took the lives of eight people in the flooded mine, was caused by a combination of hydro geological, technical and organizational factors, an inquiry into the causes of the accident announced.
An anomalous hydro geological complexity of the deposit caused by a system of unfavorably underlying cracks in the structural fault was one of the main reasons.
The Head of the Federal Environmental, Industrial and Nuclear Supervision Service of Russia, Alexey Aleshin, presented the enquiry's findings to ALROSA President Sergey Ivanov following the completion of the investigation.
The director and chief engineer of the company’s Mirny Mining Division were suspended by Ivanov, and subsequently dismissed from the company.
Aleshin ordered a commission to carry out a technical investigation into the causes of the incident, with four expert groups created of leading Russian specialists and scientists.
Among the technical reasons cited were a number of design decisions, in particular, the project of ‘dry conservation’ of the open-pit mine implemented in the early 2000s which did not take into account the possibility of washing out of ore and rocks. "It did not provide for a long-term performance of the pumps installed at the bottom of the open pit for pumping out incoming water," according to the report. "The technological regulations and development projects contained no technology for backfilling of washouts in the mine workings. The storage of salt on the open pit edge contributed to the early failure of water-circulation galleries of the ‘dry conservation’ system."
The commission also reported that hydro geological observations were conducted within the ore body only, and the project did not provide for the monitoring of brine inflows. This led to the unreliable assessment of the changed hydro geological situation at the open-pit mine.
"It should be noted that the conditions that resulted in the accident did not emerge abruptly, it took them several years to develop. ALROSA experts observed no signs of an emergency. The monitoring system did not predict the emergency either. Today, there are no reliable control systems in Russia and abroad that can make it possible to identify the development of cavity formations in rocks."
The commission developed organizational and technical measures to localize and eliminate the causes of the accident, and identified 16 officials responsible for the violations that led to the accident. According to the company’s order, ALROSA’s management must determine the complete list of persons and their personal responsibility for the accident.
Image: courtesy of ALROSA
