Mechanistic Investigation for Solidification of Pb in Fly Ash by Alkali Mineral Slag-Calcium Chloroaluminate as an Example

With the increase in municipal solid waste incineration, fly ash, its heavy metal content, and its disposal methods have attracted wide attention. This work investigates if the alkali-activated mineral slag gel solidification of heavy metals in fly ash has positive significance in promoting the harmless treatment of fly ash. This study obtained the optimal solidification conditions of fly ash from a grate incinerator, which are mineral slag content of 40%, activator content of 4%, and water content of 27.5%. Furthermore, the stability of synthesized calcium chloroaluminate is systematically investigated. The solidification effect of calcium chloroaluminate on Pb at pH = 10-13 was conducted at ambient temperatures from 15 degrees C to 35 degrees C to simulate the solidification environment of fly ash. The results show that the adsorption capacity of calcium chloroaluminate to Pb in a strongly alkaline environment is 0.1-3.5 mg/g. Pb is mainly solidified as lead-acid calcium chloroaluminate. This work provides a novel treatment strategy for fly ash.

Automated summary

This study investigates the solidification of heavy metals in fly ash using alkali-activated mineral slag gel, and explores its significance in promoting the harmless treatment of fly ash. The optimal solidification conditions for fly ash from a grate incinerator are determined, and the stability of synthesized calcium chloroaluminate is examined. The results show that calcium chloroaluminate can effectively solidify lead in a strongly alkaline environment.