At the underground development of the sulfide deposits by the systems with a consolidating stowing, the temperature of the ore mass and the mine atmosphere increases due to the heat released during the hydration reaction of the hardening mixtures. This facilitates the activation of the oxidizing processes occurring in the sulfide ores. As a result, the areas with a reduced oxygen content are formed in the extended upstream workings. A decrease of the oxygen content in the working atmosphere below the critical values is a source of mortal danger for the underground mine personnel.
These assumptions were confirmed when analyzing the causes of the emergency at the Taimyrsky mine of PJSC «MMC «Norilsk Nickel». The production here is carried out with the application of slicing and chamber mining systems with the filling of the mined-out space by the consolidating stowing. Main ore minerals: pyrrhotite, chalcopyrite, cubanite, talnakhite and pentlandite, which chemical activity testifies to their potential fire hazard. Solid (rich) sulfide copper-nickel ores are prone in the fragmentary and crushed state to oxidation by air oxygen accompanied by the formation of heat. More intensive oxidation occurs in the presence of moisture and air flow through the crushed ore.
The calculations showed that the high air temperature, along with the presence of wet ore dust and fines in the dead-end mine where the accident occurred, contributed to the occurrence of critical deoxygenation of the atmosphere, which was the objective cause of the incident. In order to avoid the recurrence of this situation, it is required to control the oxygen content in the dead-end mine workings located near the filling mass. In addition, accidental penetration of people into these workings should be completely excluded.