Process intensification of low concentration magnesium sulfate 2027 Minerals

Rare earth elements (REEs), particularly middle and heavy REEs, are strategic metals critical to advanced technologies. Ion-adsorption type rare earth ores (IAREOs) constitute the primary global source of these REEs, making the development of efficient and environmentally friendly extraction methods highly significant. Conventional in-situ leaching using magnesium sulfate suffers from high reagent consumption and prolonged percolation cycles. Here, we introduce a novel approach combining low-concentration magnesium sulfate leaching with pulsed microwave irradiation, and establish a microwave-coupled column leaching system simulating in-situ conditions. Comparative experiments with conventional heating leaching reveal that, under low microwave energy density (1.19 W/g), a pulse regime of 20 s on – 5 min off optimally enhances leaching performance. Relative to conventional heating leaching, pulse microwave assisted leaching accelerated seepage by 32% – 39% and increased REEs extraction efficiencies by 6.42% – 10.73%. The study further explores pulsed microwave-assisted gradient injection leaching. A two-stage injection scheme (stage I: 1.25 wt% MgSO4, L/S of 2:5; stage II: 0.5 wt% MgSO4, L/S of 3:5), corresponding to a total MgSO4 concentration of 0.8 wt%, achieves a REEs recovery of 90.12%, representing a 20.54% increase compared with conventional continuous leaching at the same concentration, demonstrating the significant enhancement effect of pulsed microwave irradiation on the leaching process.