Progress in resource utilization of calcium-based semi-dry desulphurization ash in iron and steel industry

In recent years, with the introduction of ultra-low emission policy in the iron and steel industry, nearly 70% of Chinese iron and steel enterprises have completed the collaborative treatment of sulfur and dust integration. The semi-dry desulphurization process using CaO or Ca(OH)2 as desulphurization absorbent produces a lot of desulphurization byproduct - desulphurization ash which is difficult to recycle. Relevant data show that China produces about 20 million tons of semi-dry desulphurized ash every year, which has become the third largest solid waste in China. At present, semi-dry desulphurization ash is mainly dealt with in storage, which leads to land occupation. Desulphurization ash has the characteristics of slow hydration reaction, strong alkaline and high content of metal impurities, and long-term storage will cause environmental pollution. Therefore, the utilization of semi-dry desulphurization byproducts has become a research hotspot and practical topic in the environmental field.