Study on the toxicity of fire smoke from mining conveyor belts

In recent years, mine conveyor belt fire accidents have occurred frequently, and an enormous amounts of toxic smoke generated during fire accidents seriously threaten the lives and safety of miners. To evaluate the smoke toxicity from mining conveyor belt fires and determine the characteristic gases for early warning of the fire, the combustion performance test and smoke density infrared spectroscopy combined test were employed to qualitatively and quantitatively analyze the change patterns of combustion products, and the index toxicity (CIT) and fractional effective dose, toxicity evaluation models, were used to evaluate the toxicity of combustion products. The results of this study showed that the heat release rate and smoke release rate of the conveyor belt had similar trends under different thermal radiation intensities, and the peak values of the heat release rate and smoke release rate increase with the increase in thermal radiation intensity. A total of 19 gas-phase substances were detected in the combustion products, among which the conventional index of toxicity of CO and HCl were 1.007 and 10.43 times the reference value, respectively, which are the leading causes of casualties in mine conveyor belt fires. In addition, the CIT of SO₂, HCN, NO₂, and CO₂ was 38.79%, 36.98%, 26.05%, and 9.00% of the reference value, respectively, all of which are highly toxic. Therefore, the above six types of gases can be used as indicator gases for conveyor belt fire early warning. The results of this study have vital guiding significance for the planning of escape routes and early monitoring and warning for personnel in mine conveyor belt fires.