材料期刊网

The relationship between Pb leaching concentration and the solution’s pH with time was analyzed when cement in its solidiifed form was leached in an acid medium. The effects of the particle size of the solidified form, the cement adding method, and the hydration degree on Pb solidification were also investigated. The experimental results indicate that cement is quickly dissolved and hydrated in the acid medium, forming a C-S-H gel or silicic acid sol with good adsorption. When cement-Pb solidified form is leached in an acetate solution, the hydrated product erodes with time, so the Pb concentration increases slightly in the beginning. Then, some of the Pb ions are absorbed by the newly generated silicic acid sol, C-S-H. Others produce Pb(OH)2 precipitation for secondary solidification, leading to a gradual decrease in the Pb concentration in a leaching time of more than two hours. Moreover, the particle size of the solidiifed form has important effects on the Pb dissolution. When the amount of added cement is low, with a pH of less than 9.5, the solidiifcation affects the sequence of the original cement powder, the cement hydrated powder, and the cement-Pb solidiifed form. When the added amount of cement increases with a pH of more than 11, the effect of adding methods on solidiifcation decreases, and the solidiifed form is a little better than others.