Current situation and development prospects of metallurgical by-product gas utilization in China's steel industry.

China's annual metallurgical by-product gas production exceeds 1400 billion Nm3, the calorific equivalent of ∼266 million tonnes of coal. The widely-studied blast furnace gas used in hydrogen-enriched carbonic oxide recycling oxygenate furnaces ensures carbon-reduction. Converter gas contains abundant heat resources, equivalent to ∼6.5 million tonnes of coal. Using high-temperature by-product gas online reforming methods to convert thermal energy into chemical energy and combining it with power generation and other industries imparts physical heat recovery exceeding 60%. China's annual coke oven gas (COG) production could support more than 100 million tonnes of direct reduced iron production, thus reducing CO 2 emissions by more than 150 million tonnes (nearly 10% of China's steel industry CO 2 emissions). We summarise the characteristics, availability, and steel-chemical co-production utilisation of three by-product gases, and discuss the application of COG in direct reduced iron production and development of metallurgical by-product gas utilisation for carbon reduction in China. • Development direction of metallurgical by-product gas. • The utilisation of by-product gas in steel-chemical co-production. • Coke oven gas for direct reduction ironmaking. • Online reforming method to convert thermal energy into chemical energy. • Blast furnace gas for hydrogen-enriched carbonic oxide recycling oxygenate furnace. [ABSTRACT FROM AUTHOR]