Cement based solidification/stabilization of arsenic-contaminated mine tailings

Cement was used to solidify/stabilize the abandoned mine tailings contaminated primarily with arsenic (up to 88 mg/kg) and lead (up to 35 mg/kg). Solidified/stabilized (s/s) forms with a range of cement contents, 5–30 wt%, were evaluated to determine the optimal binder content. Unconfined compression strength test (UCS), Korean standard leaching tests, toxicity characteristic leaching procedures (TCLP), and synthetic precipitation leaching procedure (SPLP) were used for physical and chemical characterization of the s/s forms. Addition of 5% cement was enough for the s/s forms to satisfy the UCS requirements (0.35 MPa). The addition of 7.5% cement remarkably reduced the leachability of arsenic in tailings. However, that of lead tends to increase slightly with increase of cement content due to its amphoteric nature. The discussions were made for determination of optimal binder content and for results from different evaluation procedures.