含氟生物浸出体系中阳离子竞争络合解毒机理研究

针对生物浸出体系中氟对浸矿微生物的抑制问题，提出结合氟的溶液化学性质，利用金属阳离子的竞争络合作用，使溶液中的游离F^-形成络合态，进而使细菌可耐受高氟浓度生长。比较了不同金属氟化物对细菌生长的影响，结果显示：AlF₃和FeF₃性质稳定，对细菌生长无明显影响；MgF₂溶于浸出体系释放F^-，对细菌产生毒害作用。热力学分析结果表明，Al³⁺、Fe³⁺对F^-的竞争络合机理以及Mg²⁺对F^-无竞争络合符合热力学定律。比较了Al³⁺和Fe³⁺对F^-的解毒能力，结果表明，Al³⁺、Fe³⁺对氟均有解毒作用，解毒能力大小为Al³⁺>Fe³⁺。通过PHREEQC计算可知，络合物形态可通过调节溶液中F^-与金属离子的浓度控制，且随着F^-与金属离子浓度比的减小，配位数向低配位方向移动。

Research of Fluoride Detoxified by Cation and Its Competitive Complexation Mechanism in Fluoride-bearing Bioleaching System

In order to solve the problem of fluoride inhibition on leaching microorganisms in bioleaching system, the chemical properties of fluorine were proposed. The competition complexation of metal cations was utilized to alternate the free F^- into complex state, thus made it possible for bacteria growth under high fluoride concentrations. The effects of different metal-fluoride complexes on bacteria growth were compared. The results show that the stability of AlF₃ and FeF₃ has no obvious effect on the bacteria growth, and MgF₂ dissolves in the leaching system to release F^- ions, which has a toxic effect on bacteria. Through thermodynamic analysis, it is found that the competitive complexation mechanism of Al³⁺ and Fe³⁺ to fluoride ions and the non-competitive complexation of Mg²⁺ ion to fluorine are in accordance with the laws of thermodynamics. The detoxification abilities of different cations (Al³⁺, Fe³⁺) to fluoride ions were compared. The experiment results of different metal cations competitive complexation to fluorine show that Al³⁺ and Fe³⁺ are able to detoxify to fluorine, the detoxification ability to fluorine is in the order of Al³⁺>Fe³⁺. The complex species were calculated by PHREEQC. The results show that the complex species can be controlled by adjusting the concentration ratio of fluoride and metal ions in the solution, and with the decrease of the concentration ratio of fluorine and metal ions, the coordination number moves to the low coordination direction.