烧结升温方式及气氛对水洗焚烧飞灰晶体演变的影响

Effect of heating program and atmosphere on the evolution of crystal washed fly ash during calcination

为使水洗焚烧飞灰的稳定化处理进一步优化,探讨了热处理的加热过程、气氛条件等对水洗焚烧飞灰晶体成分演变的影响.同时也探讨了3种飞灰:锅炉飞灰(RFA)、CaO/Ca(OH)2和NaHCO3分别作为中和剂得到的两种飞灰(CaFA和NaFA)水洗后(RFA-II#、CaFA-II#和NaFA-II#)进行热处理比较.结果发现700℃是个转折点,从这个温度点开始3种水洗飞灰中的晶体成分发生明显变化;原位连续加热模式更容易形成固体溶液因而更适合重金属的稳定;NaFA-II#较之CaFA-II#更易于稳定重金属成分.Factsage的模拟结果与XRD结果一致,而且发现飞灰中氯化物在加热过程中首先释放的是HCl.

In order to optimize the stabilization of washed municipal solid waste incineration(MSWI)fly ash(FA)by calcination,the influence of the heating method(continued-heating,multistep-heating)and atmosphere conditions on the evolution of crystal composition in washed FA was discussed.Three kinds of FA(RFA-II#、CaFA-II#and NaFA-II#)were tested and compared.RFA was the boiler fly ash(RFA),CaFA and NaFA were FA resulted from discharged gas neutralized by CaO/Ca(OH)2 and NaHCO3 respectively,and“II#”means they were dried residues treated by a double washing process.The results indicate that continued-heating was easier to form solid solution to stabilize heavy metals,and 700°C was the turning point after which the crystal in three FAs changed obviously.The FA neutralized by NaHCO3 was better to stabilize heavy metals.The simulation results from Factsage were consistent with the XRD results,and it was found that HCl was the first evaporation chloride released from the washed FA during the calcination process.