Pozzolanic activity enhancement of magnesium-rich nickel slag and geopolymer preparation

The pozzolanic activity of magnesium-rich nickel slag (HMNS) was improved by remelting and quenching method, the changes of mineralogical phase, microstructure, elements distribution of HMNS remelted and quenched by water were characterized, and the dissolution of Si, Al and Ca required for geopolymerization was also determined. The dissolution amount of Si, Al and Ca for treated HMNS were increased from 1.21, 1.66 and 0.35 mg/g to 6.24, 8.63 and 1.82 mg/g, respectively. From the results of XRD and FTIR, the crystal phases in HMNS after remelting water quenching was transformed into amorphous state, and the substances in treated HMNS mainly existed in the form of vitreous phase. And there was a phase-separated structure of Si-rich region and Ca-rich region on the basis of observation of microstructure and elements distribution. 70wt% of treated HMNS and 30% of FA were used to prepare geopolymer, and found that the compressive strength of geopolymer cured for 28 d was 42.2 MPa, increased by 78.5% compared to the counterpart prepared by untreated HMNS. These results confirm strong effects of the remelting and water quenching treatment on enhancement of pozzolanic activity of HMNS, and could provide help for the utilization of HMNS to prepare geopolymer.