Valorization of Delithiated β−Spodumene as a Raw Construction Material

With the ecological transition and the move towards net zero emission, lithium is the subject of much attention. Lithium is a key element in the manufacturing of batteries for electrical vehicles, which are expected to dominate the market in the European Union from 2035 onwards. Lithium occurs in more than 100 minerals including spodumene, petalite, or lepidolite. In Australia, spodumene is the main source of hard rock lithium. Australia is the world leader in lithium production, with five mines representing almost half of the world’s total lithium production in 2022. It is ranked second in the world in terms of proven reserves, with 6.2 million tonnes. Spodumene contains about 6% Li₂O when it is pure. In order to extract lithium, α-spodumene must undergo a phase transformation that is activated by heat. Therefore, the spodumene processing results in several waste components both in the solid and liquid streams. The solid residue may contain aluminosilicates that are intrinsic to the spodumene crystal and other components that are due to the process itself including sodium sulphate (obtained upon sulphating β-spodumene) and various hydroxides that result from the acid neutralisation. Overall, significant quantities of residues can be formed that can become an environmental burden if not reused in a circular economy. The objective of this research is to elaborate geopolymer mortars with different proportions of β-spodumene as alkali-activated materials and slag. It has been established that an optimum binder is obtained with 25% β-spodumene and 75% slag.