微生物浸出-浮选协同作用制备超纯铁精矿的基础研究

Ultrapure iron concentrate, a further processed product of magnetite concentrate, which important quality index is the content of silicon. The gangue mineral of magnetite concentrate are dominated by quartz and Fe-bearing silicates. Flotation and low-field magnetic separation can be also applied to reduce quartz, but Fe-bearing silicates and magnetite separation by processing is difficult because of their similar physical and chemical properties. It is, therefore, decided to study the possibility of leaching Fe-bearing silicates by silicate bacteria which is used to selective dissolve silicate and reverse flotation quartz using silicate bacteria and its metabolites as flotation reagent. Moreover, the multiple testing technologies will be combined to further study the adsorption morphology and interaction on minerals surface by microorganism and its metabolites. And then the relation between mineral crystal structure and leaching rate by microorganism is established. The floatability of minerals after interaction with the polysaccharide and protein from microbial metabolites is investigated. Based on the above, the adsorption characteristics of microorganism and its metabolites on the surface of the silicon containing minerals will be revealed, and leaching mechanism of Fe-bearing silicate by microorganism is elucidated. The relations between flotation behavior of quartz and magnetite and adsorption behavior of microbial flotation reagents are built certainly. Finally a technical prototype for desiliconization of magnetite concentrate by bioleaching and bio-flotation is achieved after establishing the relationship between Fe-bearing silicates leaching behavior and microorganism. The research is in order to provide new theory and technical support for preparing ultrapure iron concentrate.

超纯铁精矿是常规磁铁矿精矿进一步分选深加工的产品，硅含量是衡量超纯铁精矿质量的最重要指标。铁精矿中的杂质石英可由浮选、弱磁选等分选方法脱除，但含铁硅酸盐矿物与磁铁矿物化性质相似，难与磁铁矿选矿分离。本项目利用可选择性分解硅酸盐矿物的微生物浸出铁精矿中的含铁硅酸盐矿物，浸矿微生物及其代谢物反浮选脱除石英，并结合多种测试技术，深入研究微生物及其代谢物在矿物表面的吸附形貌和相互作用，矿物晶体结构与微生物浸出的关系，以及微生物代谢多糖和蛋白质作用下矿物可浮性的变化，揭示微生物及其代谢物在含硅矿物表面的吸附特性，阐明微生物对含铁硅酸盐矿物的浸出机理，建立含铁硅酸盐矿物浸出行为与浸矿微生物之间的关系，以及石英和磁铁矿的浮选行为与微生物浮选药剂吸附行为之间的关系，形成微生物浸出-浮选脱硅技术原型，为我国超纯铁精矿的制备提供新的理论和技术支撑。

含铁硅酸盐矿物与磁铁矿物化性质相似，难以选矿分离。微生物浸出与浮选是利用微生物及其代谢物选择性溶解矿物或改变矿物表面的亲疏水性实现矿石脱硅的重要方法。本项目主要围绕可选择性浸出含铁硅酸盐矿物的微生物在磁铁矿与含铁硅酸盐矿物表面的吸附规律和界面作用及其对矿物可浮性的影响核心研究目标，系统地开展了可浸出含铁硅酸盐矿物中硅的微生物筛选，微生物浸出含铁硅酸盐矿物的规律与机理，浸矿微生物及其代谢物对磁铁矿与含铁硅酸盐矿物可浮性的影响研究，阐明了浸矿微生物及其代谢物在矿物表面的吸附特性和界面作用机理以及其对矿物可浮性的影响规律，建立了微生物浸出与浮选脱除磁铁矿石中含铁硅酸盐矿物的关系。筛选出的多粘类芽孢杆菌、胶质芽孢杆菌、解淀粉芽孢杆菌三株细菌可浸出含铁硅酸盐矿物中硅，其中解淀粉芽孢杆菌浸矿脱硅效果显著。细菌浸出结果表明，层状结构和架状结构的含铁硅酸盐矿物易被细菌浸出，单链与双链结构含铁硅酸盐矿物浸出效果略差。细菌浮选分离磁铁矿与含铁硅酸盐矿物实验结果表明，细菌培养液为浮选药剂时，磁铁矿与含铁硅酸盐矿物浮选分离效果较好，细菌在磁铁矿与含铁硅酸盐矿物表面吸附量差及细菌代谢物对磁铁矿的抑制起主导作用；细菌浸矿作用后，磁铁矿与金云母可浮选分离，但与石英难以分离，细菌在金云母表面吸附量较多，磁铁矿与石英对细菌的吸附作用相近。在分析浮选药剂组合使用、抑制剂对磁铁矿与含铁硅酸盐浮选分离影响规律与机理的基础上，初步提出了细菌浸出-浮选协同脱除磁铁矿石中含铁硅酸盐矿物的工艺，为超纯铁精矿的制备提供了理论指导。