Transformation of mine tailings into cement-bound aggregates for use in concrete by granulation in a high intensity mixer

Abstract

Mine tailings pose one of the world's largest volumes of challenging residues. To overcome the environmental liability and reduce monitoring and reclamation costs associated with the long-term storage of tailings – and to add extra income to the miners' activities – sustainable solutions and new applications for such residues seem prudent. The aggregate market may be able to absorb significant volumes of tailings. Due to the fineness of tailings, however, a granulation process is required. The tailings studied in the present work originated from the flotation process of a non-ferrous multi-metal mine and were mostly composed of limestone and quartz. The granulation process with a cement binder in a high intensity mixer was studied in detail in this paper. An optimization of the mixing parameters resulted in granules with a single granule crushing strength of 3.1 MPa when using only 5 wt% of CEM III/B as binder (95 wt% of tailings). The optimal granules were tested in mortars by partially replacing standard quartz sand (17 and 32 wt%). Compressive strength after 28 days of 44 MPa was obtained and the leaching of heavy metals was suppressed by using CEM III/B as cement binder.