The extraction of lithium from spodumene produces leached spodumene concentrate (LSC) as a mineral by-product. Previous studies have demonstrated its promising pozzolanic potential and suggested its suitability as a cementitious material (SCM). This study investigates the influence of the two modifications of leached spodumene (LS) in LSC on the development of hydration phases and pozzolanic reactivity in cementitious systems. Two LSC samples with different proportions of hexagonal leached spodumene (H-LS) and tetragonal leached spodumene (T-LS) were selected and incorporated into mixed cement mixtures at 10, 20 and 30 wt% and hydrated for 28 days. Phase development was monitored using XRD in combination with quantitative Rietveld analysis. In addition, thermogravimetric analyses in conjunction with differential scanning calorimetry (TG-DSC) and isothermal calorimetry measurements were carried out to gain further insights into the hydration behaviour and reaction kinetics. Synthetically produced reference phases (α-, β- and γ-spodumene as well as H-LS and T-LS) were also characterised in terms of their pozzolanic activity. The results show no significant differences in the hydration behaviour of the two LSC samples, suggesting that both H-LS and T-LS exhibit comparable pozzolanic reactivity. Overall, the ratio of H-LS to T-LS appears to have only a minor influence on hydration performance and reactivity.
Left: Ternary system CaO – SiO2 – (Al,Fe)2O3 with slag, OPC (Portland cement) and LSC – residue from lithium extraction
Right: Leached spodumene (HAlSi2O6) (Image: J. Woskowski, Design: R. Killian)
