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Toxic gas leakage in metallurgic plants has emerged with the growth of crude steel production in recent years, causing damage to people, facilities, and the environment. Poisonous gas leakage can lead to other severe accidents including fires, explosions and gas poisoning. In this paper, we propose a risk assessment system (RAS) for toxic gas leakage using a fuzzy evaluation method integrating the entropy weighting method (EWM) and the order relationship method (ORM) and compiled an index system consisting of four first-level indices and fifteen secondary indices. The first-level indices are blast furnace safety performance, protective facilities, evacuation and dilution facilities, and poisonous gas management. The four first-level indices’ toxic gas leak evaluation result is 0.8581, 0.8971, 0.7733, and 0.8652, respectively. We observe that the overall status of the metallurgical plant is “excellent”, yet the result for the evacuation and dilution facilities was less than 0.8, indicating that there is still room for improvement. The risk evaluation time is reduced by forty percent by adopting RAS.

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In this study, to explore the influence of metals and oxides on the oxygen production rate and stability of sodium chlorate oxygen candles, 28 experimental samples were investigated. The effects of Co2O3, Co3O4, and Fe2O3 with different mass fractions on the thermal decomposition temperature and thermal decomposition rate of sodium chlorate were compared and analyzed. Co3O4 (5%) was obtained to reduce the thermal decomposition range to 260–450°C and reduce the pyrolysis interval ∆T to 46.2°C. Through the development of three metals (Fe, Mg, and Mn), under four mass fractions (2%, 4%, 6%, and 8%) mixed with Co3O4 (5%), the results of the effective oxygen production efficiency test for the thermal decomposition reaction of sodium chlorate demonstrated that Mn (6%)–Co3O4 (5%) exhibited the best catalytic and heat coupling effect; the effective oxygen production efficiency of 97.8% was achieved. Oxygen candle oxygen supply experiment was conducted; the oxygen candle composition for the test was determined to be NaClO3 (86%), Mn (6%), Co3O4 (5%), and kaolin (3%); in the four stages of the oxygen candle oxygen supply reaction test, the average oxygen supply rate reached 1.647 L/min, actual oxygen production was 28 L, and effective oxygen production rate of the oxygen candle was 53.6%. An increase of 9% was observed compared to the previous similar studies. The results of this study present a formula to optimize the oxygen supply of the oxygen candle, which is crucial for improving the oxygen supply performance of the oxygen candle.