铀矿石生物浸出中氟对铁-硫氧化细菌的影响

Influence of Fluorine Ion to Iron-Sulfur Oxidizing Bacteria in the Uranium Bioleaching

本文针对某铀矿矿石氟含量高的特点,研究了铀矿石生物浸出过程中矿石浸泡液中pH值与氟离子浓度变化规律、不同起始氟离子浓度对铁-硫氧化细菌生长发育的影响以及所选用铁-硫氧化细菌对氟离子的适应能力。结果显示,铀矿石中氟离子浓度随着生物浸出体系中pH值由高到低的变化而呈现出由低到高的线性变化特征;试验用铁-硫氧化细菌对氟离子非常敏感,20 mg/L氟离子便会抑制其生长;但经过较高浓度含氟离子培养基长时间培养选择后筛选所得到的菌株却对较高浓度氟离子生长基质有较强的耐受性,如菌株Z-1可在含氟1.48 g/L的溶浸液中一昼夜即可将5 g/L Fe2+完全氧化。研究结果表明,通过驯化可以获得耐氟铁-硫氧化细菌,将其应用于生物浸出工艺中,既不会降低铀浸出率,也不需额外的经济投资。

The variation rules between pH value and fluorine ion concentration in the uranium ore soaking solution, the influence of different originated fluorine ion concentration to the iron-sulfur oxidizing bacteria growth and the bacteria＇s adapted ability to fluorine ion in the process of uranium ores bioleaching have been investigated against the characteristic of higher grade fluorine in the uranium ores. The consequence reveals that the fluorine ion concentration is continuously rising up while the pH is falling down, and the strains of bacteria used in this research are greatly sensitive to fluorine ion, such as, fluorine of 20 mg/L would inhibit growth of the bacteria. And result also shows that the strain can tolerate the higher fluorine ion concentration after a long time period domestication in high fluorine-containing culture. For example, after domestication, strain of g - 1 can completely oxidize 5 g/L Fe^2＋ in fluorine-containing culture （fluorine ion concentration is 1.48 g/L） in 24 h. The con- clusion indicates that iron-sulfur oxidizing bacteria can acclimate the environment of fluorine-containing by domestication and its application in bioleaching not only elevate the uranium leaching rate, but also reduce the economic investment.