Phase Transformation Processes and Mechanisms of Inderite in Deionized Water and Magnesium Sulfate Solution at 308.15 and 323.15 K

Salt lakes are rich in boron, magnesium, potassium, lithium, and other elements of considerable industrial significance. Boron serves as a crucial tracer for investigating geological processes due to its high incompatibility and solubility. However, boron tends to form complex borates with other elements in salt lakes such as magnesium borates. The excessive accumulation of boron in brine, coupled with the phase transition of magnesium borate that releases boron, complicates the study of the boron cycle and contributes to environmental pollution. Therefore, investigating the phase transitions of borates and identifying stable solid phases at various temperatures are crucial for enhancing our understanding of the boron cycle and mitigating pollution in salt lakes. This paper investigated Mg2B6O11–H2O (308.15, 323.15 K) and Mg2B6O11–MgSO4 (5, 10, 20 and 30%)–H2O (308.15 K) systems via isothermal dissolution equilibrium, thermogravimetry, and X-ray diffraction. At 308.15 K, Mg2B6O11–H2O began converting to pinnoite at 237 h, reaching equilibrium at 1000 h; at 323.15 K, conversion started at 33.5 h and finished within 170 h. In MgSO4 solutions (5–30%), inderite remained stable for 68–94 days without transformation.