螯合剂与鳌合工艺协同强化垃圾焚烧发电飞灰固化—脱盐一体化及应用

Enhanced solidification-desalination integration and application of waste incineration fly ash by chelating agent and chelating process

经济的快速发展使得城市垃圾处理问题日益严峻,垃圾焚烧发电是处理生活垃圾的主流手段。但垃圾焚烧过程中产生的飞灰对人体健康和生态环境具有较大危害,亟需高效且经济的飞灰固化技术,防止填埋过程中重金属浸出。依据重金属矿化及地球化学原理,利用磷酸盐和硫化物复配形成高效螯合剂。在实验室中取得了显著的固化效果,固化后飞灰浸出液中重金属含量均远小于国标。但是,在中试放大试验中,传质差大大限制了螯合效果。为了强化传质,改进鳌合方式,将鳌合剂浓度稀释至1%,与飞灰形成浆料鳌合,最后再利用板框过滤或离心分离,实现重金属固化与盐类分离的协同,进而提出了新型鳌合工艺,在500 kg规模中试也取得了显著固化效果,其飞灰浸出液中12种重金属含量也远小于国标限制,更重要的是该技术还能从飞灰中回收钾盐和钠盐。因此,复配型螯合剂和新型鳌合工艺协同是一种强化垃圾焚烧飞灰固化的高效方法。

The treatment of urban waste is becoming more and more imperative with the rapid development of economy.Waste incineration power generation is the mainstream means of dealing with domestic waste.However,the fly ash produced in the process of waste incineration is very harmful for human health and ecological environment.Therefore,efficient and economical technology for fly ash solidification is urgent to prevent leaching of heavy metal during landfill.Herein,efficient chelating agent was formed by phosphate and sulfide based on the principle of heavy metal mineralization and geochemistry.Significant curing effects have been achieved in the laboratory,and the heavy metal content in the fly ash leaching solution after curing is far less than the national standard.However,poor mass transfer greatly limits the chelation effect in the pilot scale-up test.The chelating method was modified to strengthen the mass transfer.The concentration of the chelating agent is diluted to 1%,and then form a slurry with the fly ash,finally plate and frame filtration or centrifugal separation are used to achieve the synergy between the solidification of heavy metals and the separation of salts.As a result,a significant solidification effect was also achieved in a 500 kg pilot test with modified chelating process.The content of 12 heavy metals in the fly ash leaching solution is far less than the national standard limit.More importantly,the potassium and sodium salts were also recovered from the fly ash.Obviously,the synergy of the compound chelating agent and the new chelating process is an efficient method to strengthen the solidification of waste incineration fly ash.