中国有色冶金

In the novel beryllium extraction process, which involves low-temperature dissociation of beryllium ore followed by physical purification of beryllium-containing compounds, the physical purification step is achieved by exploiting differences in the solubility of fluorides, thereby enabling efficient separation of impurities. As one of the main impurities in beryllium ore, manganese and the dissolution behavior of MnF₂ have received relatively little attention in previous studies. This work systematically investigates the dissolution characteristics of MnF₂ in both H₂O and H₂O-HF systems during the removal of manganese-containing fluorides in beryllium ore smelting. The following key conclusions were obtained. MnF₂ exhibits low solubility in water, and its solubility decreases with increasing temperature. In the presence of HF, it reacts to form soluble H₂MnF₄, resulting in a slight increase in solubility. The theoretical solubility of MnF₂ is 0.69 g/100 g, while the experimentally measured value is 0.78 g/100 g. After dissolution, it exists predominantly in ionic form. In the H₂O-HF system containing BeF_2， BeF₂ demonstrates relatively high solubility. However, owing to its small equilibrium constant, both BeF₂ and H₂BeF₄ coexist in the solution, and the concentration of H₂BeF₄ is governed by both temperature and HF concentration. HF and MnF₂ simultaneously supply F-, which coordinate with BeF₂ to form BeF^2-₄. This complex subsequently combines with Mn²⁺ to produce insoluble MnBeF₄, thereby facilitating the removal of impurities. Unbound coordinating ions remain in solution as H₂BeF₄.