Study on the performance of water washing dechlorination from domestic waste incineration fly ash and the leaching characteristics of heavy metal Zn
The single factor experiments and response surface optimization experiments were conducted to explore the optimal water washing conditions for dechlorination and the optimal leaching conditions for Zn in domestic waste incineration fly ash.The results showed that under optimized conditions(washing temperature 35 ℃,washing time 10 minutes,washing liquid-solid ratio 10 mL/g),the dechlorination of fly ash could reach 73.4％.After secondary washing,the removal rate of chloride ions reached 96.8％.The leaching characteristics of Zn in fly ash were compared using different types of acids.The results showed that the leaching rates of different leaching agents were as follows:hydrochloric acid＞nitric acid＞tannic acid(TA)＞diethylenetriamine pentaacetic acid(DTPA)＞disodium ethylene diaminetetra acetic acid(EDTA).The optimal hydrochloric acid leaching conditions for Zn were determined by response surface optimization method:liquid-solid ratio of 10 mL/g,hydrochloric acid concentration of 2.0 mol/L and leaching time of 8 hours.At this point,the leaching rate of Zn could reach 70.48％.
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