烧结烟气脱硝废弃钒钨钛催化剂资源化利用途径分析

 2019年生态环境部等五部联合印发《关于推进实施钢铁行业超低排放的意见》提出,到2025年底前,全国力争80%以上的钢铁产能完成超低排放改造。目前,烧结烟气中NO_x减排成为重中之重。以钒钨钛系催化剂为核心的氨气选择性催化还原法(NH₃-SCR)成为烟气脱硝主流技术之一,并已广泛在钢铁企业投入使用。而随着催化剂使用寿命到期,废弃催化剂产生量逐年增加。据估计,2027年前后中国烧结烟气脱硝废弃催化剂产生量将达到100 000 m3/a。钒钨钛系催化剂含有V₂O₅,具有较强的生物毒性,新版《国家危险废物名录》中,已明确将这类废弃催化剂归为“HW50”危废。随着环保要求日益严厉,加强对钒钨钛系催化剂的有效处置利用已成为钢铁工业急需解决的关键共性难题。围绕废弃催化剂的处理思路和技术手段,总结了国内外废弃催化剂处置现状。主要处理思路分为有价元素提取、废弃催化剂循环利用和无害化处置等。有价元素提取相应的技术手段包括浸出、萃取、沉淀、水热合成、碳热还原等;废弃催化剂循环利用包括掺混制备新催化剂;无害化处置包括固化/稳定化处理后填埋。随着钢铁企业“固废不出厂”的新发展理念提出,分析了以废弃催化剂作为含钛资源在钢铁生产流程中资源化利用的相关研究思路,并对废弃催化剂在钢铁企业内部高效清洁利用进行了展望。

Analysis on resource utilization of spent V2O5-WO3/TiO2 catalyst produced in sintering flue gas

In 2019, the "Proposal on promoting the implementation of ultra-low emissions in the steel industry" was presented by Chinese government, aiming to convert more than 80% of China's iron and steel capacity enterprises into ultra-low emission transformation by the end of 2025. Currently, NO_x emission reduction from sinter flue gas has become the focus. Selective catalytic reduction with ammonia (NH₃-SCR) based on vanadium-tungsten-titanium catalyst has become one of the mainstream technologies for sinter flue gas denitrification and has been widely used in iron and steel enterprises. However, as the catalysts reach the end of their life, spent catalysts are increasing year by year. It is estimated that the spent catalysts produced by sinter flue gas denitrification will reach 100 000 m3 per year in 2027 in China. Vanadium-tungsten-titanium spent catalysts contain V₂O₅, which have strong biological toxicity and have been classified as "HW50" hazardous waste in the new National Hazardous Waste List. With the increasingly stringent environmental requirements, the effective disposal of spent catalysts has become a key common problem that needs to be solved in iron and steel industry. The current status of spent catalyst disposal was summarized in terms of disposal concepts and technical methods. The main treatment methods include valuable element extraction, spent catalyst recycling and harmless disposal. The corresponding technical approaches of valuable element extraction include leaching, extraction, precipitation, hydrothermal synthesis and carbon thermal reduction. Spent catalyst recycling includes the mixing of spent catalysts to make new catalysts. Harmless disposal includes solidification/stabilization before landfill disposal. Based on the new development concept of "solid waste does not leave the factory" in iron and steel enterprises, the research ideas related to the resource utilization of spent catalysts as a titanium resource in the steel production process are analyzed. Finally, the prospect of efficient and clean utilization of spent catalysts in iron and steel enterprises is presented.