Early detection of spontaneous combustion disaster of sulphide ore stockpiles

The fire hazards induced by the spontaneous combustion of sulphide ores pose safety, environmental, and economic concerns to the mining and metallurgical industries and have become one of the most important problems in mining, particularly when sulphide ores have to be stored for a long time or transported for a long distance. The first purpose of this paper is the selection of a suitable detection indicator for running through the entire process of spontaneous combustion from oxidation to fire and accurately determining the position of the fire source of the spontaneous combustion of sulphide ore stockpiles at an early stage. We conducted on-site and laboratory experiments by using five indices to assess the oxidation characteristics of sulphide ores. Experimental results show that the change of surface temperature on sulphide ore stockpiles could indirectly reflect the nature of sulphide ore oxidation and is closely related to the various stages of spontaneous combustion. On the basis of the temperature anomaly analyses and infrared thermal imaging technology, a new fire source detection method, which can monitor the highest temperature point on the surface of self-igniting ores, was proposed. The investigation result shows that the maximum temperature differences are 0,5; 0,16 and 0,04 °C at the detection depths of 2, 3, and 5 m, respectively, and a scope of 1 × 1 m when close to the self-ignition duration. Under the same condition, the maximum temperature differences are 1,39; 0,53 and 0,14 °C at a scope of 2 × 2 m. Therefore, the infrared thermal imaging system with a sufficiently high accuracy can be used to measure the temperature differences on the surface of ore stockpiles, thus resulting in the determination of fire source position.