Efficient consolidation of Pb(Ⅱ) in fly ash by modified tourmaline combined with cement

Abstract

Aiming at the problems of high heavy metal leaching rate and large cement consumption in cement-solidified fly ash technology, the modified tourmaline was added to reduce cement consumption greatly on the basis of meeting the safety landfill standard. The influences of tourmaline addition, curing time on the compressive strength and leaching concentration of Pb(Ⅱ) were studied by indoor simulation experiment, the solidified mechanism of Pb(Ⅱ) was studied by FT-IR and XPS. The experimental results showed that when the mass ratio of the modified tourmaline: cement: fly ash was 1:2:20, the solidified efficiency of Pb(Ⅱ) was as high as 99.97% and compressive strength was 3.12 Mpa. The effect was greatly affected by the amount of tourmaline, and the cement consumption was 30% less than that of pure cement solidified. The characterization results showed that the addition of tourmaline promoted the activation of SiO<inf>χ</inf> and the hydration reaction, and enhanced the precipitation and encapsulation protection of Pb(Ⅱ), which mainly existed in the form of Pb<inf>3</inf>(OH)<inf>2</inf>(CO<inf>3</inf>)<inf>2</inf> after solidified. The results can provide references for solving the problems of high leaching concentration and large cement consumption in cement solidified heavy metal Pb(Ⅱ) technology.