Influence of Saline Sulfuric Acid Treatment on Vermiculite Process and Its Mechanism

The study of weathering alteration of phyllosilicate minerals is of great significance for understanding the chemical cycle of the earth surface, soil formation and environmental changes. A phlogopite from Xinjiang, China was used as a raw material to control the oxidation environment, pH value, ion species and concentration of sulfuric acid solution in the process of phlogopite vermiculization. The phase, composition release law, spectroscopic properties and thermal properties were characterized by X-ray diffraction, inductive coupled plasma emission spectroscopy, Fourier transform infrared spectroscopy, and thermogravimetry-differential scanning calorimetry, respectively. The results show that the degree of vermiculite increases with the increase of Mg²⁺ ions concentration in the solution, but the less conversion effect exists at a certain H₂O₂ content in the solution. The conversion effect can be enhanced after the use of sulfuric acid to adjust the solution pH value, because the acidic environment can improve the oxidation capacity of hydrogen peroxide and the increase of SO₄^2– ions concentration. The more jarosite substances are formed, thus accelerating the process of vermiculization.