Immobilisation of high-arsenic-containing tailings by using metallurgical slag-cementing materials.

The mixture of finely ground blast furnace slag (BFS), basic oxygen furnace (BOF) steel slag (SS), and flue gas desulfurisation (FGD) gypsum could be used as cement to solidify heavy metals. In this study, these cementitious materials were combined with high-arsenic-containing tailings to form cemented backfill material (CBM). The results indicated that the optimal design of CBM was that of specimen CBM2 which showed good early strength (10.09 MPa) at a curing age of 3 days containing 60% BF slag, 30% SS, and 10% gypsum. And the arsenic leaching concentration of CBM2 at a curing age of 7 days and 28 days were both less than the limits specified in standards for drinking water quality (Chinese Standard GB 5749-2006). The predominant hydration products of CBM2 contained rod-like ettringite and amorphous C-S-H gel both of which promote arsenic solidification.