Effect of Potassium Salt on Swelling of Halloysite Clay Mineral during Leaching Process of Ionic Rare Earth Ore

Abstract

Currently, the primary method for leaching rare earth ores is through in situ leaching. This approach involves contact between clay minerals and liquids, which can lead to the potential swelling of clay minerals with water, triggering natural disasters such as landslides. The main purpose of this study is to select the suitable anti-swelling solution for Hunan Jianghua ionic rare earth ore. According to the ore composition analysis, 88 wt% of Hunan Jianghua ionic rare earth ore is composed of halloysite clay mineral. Therefore, halloysite clay mineral is used to investigate its anti-swelling behavior in order to provide a reference for future research on the selection of raw ore swelling inhibitors. In this study, the traditional leaching agent, MgSO4 solution, was used as the solvent along with two additional compounds, CH3COOK and KCl, which were prepared in different concentrations to form a new composite swelling inhibitor solution to observe their effect on the swelling rate of halloysite clay mineral. At the same time, the seepage velocity of halloysite clay mineral with different anti-swelling solutions is studied. The results indicate that the optimal concentration in the CH3COOK + MgSO4 solution system is 0.05 mol/dm3. At this concentration, the swelling rate is 5.129%, the inhibition rate is 20.08%, and the seepage velocity rate is 12.51 × 10−3 cm/min, respectively. In KCl + MgSO4 solution, the swelling rate is 4.868%, the inhibition rate is 24.15% and the seepage velocity rate is 13.23 × 10−3 cm/min at the concentration of 0.02 mol/dm3, which is the optimum concentration. In addition, FTIR and TG studies have further demonstrated the mechanism by which these two composite bulking inhibitors inhibit the swelling of halloysite clay mineral.