Strengthening extraction of lithium and rubidium from activated α-spodumene concentrate via sodium carbonate roasting

As a critical resource, lithium is necessary for the flourishing of clean energy as an upstream raw material. With the global popularity of lithium batteries and strict requirements for environmental protection, a short, cost-effective lithium extraction process from α-spodumene was critical. In this paper, a novel process for efficient and direct extraction of lithium from α-spodumene was proposed. The main contents of the process were sodium roasting, water quenching and strengthening leaching. Firstly, the thermodynamic behavior of the roasting products was analyzed using Factsage 7.0 software. Subsequently, the factors of lithium extraction were investigated by single-factor condition experiments. And the response surface methodology (RSM) was used to carry out the three-factor and three-level Box-Behnken experiments. The investigation revealed that α-spodumene reacted directly with Na2CO3 at high temperature to form Li2SiO3, NaAlSiO4, and Na2SiO3. The stable aluminosilicate structure in α-spodumene was destroyed by the combined effect of sodium roasting and water quenching, which played a significant role in the release of lithium. In addition, the Na2CO3 dosage dominated the effect of lithium extraction, followed by roasting temperature and roasting time. Based on the model optimization results, the optimal roasting conditions were determined to be roasting at 1100 °C for 30 min with the addition of 45% Na2CO3. The extraction rates of Li and Rb were 95.9% and 90.3%, respectively, whereas those of Al was only 1.5%. This process provides a technological solution for the high-efficiency and synergistic extraction of valuable elements in α-spodumene.