Bio-reduction of Co and Ni bearing Manganese Minerals

红土和锰结核是微生物法提取钴的潜在新来源。开发这些资源和优化加工路径的关键是了解微生物-铁和锰矿物界面上的氧化还原反应。确定微生物与含钴铁、锰羟基氧化物相之间的相互作用机理，对于了解钴的自然生物地球化学循环，以及这种具有重要技术意义的金属在生物加工过程中从潜在矿石中释放是至关重要的。这些通常结晶较差的含铁富集物的铁和锰矿物学由铁和锰羟基氧化物组成，钴以Co(II)和Co(III)的形式存在。微生物异化还原Fe(III)和Mn(IV)提供了从这些来源中提取Co的途径；在关键的微生物-矿物相互作用中，Mn对电子传递过程的控制不如Fe，对Co和Ni的控制也很少。包括脂多糖在内的胞外聚合物被认为在微生物-矿物相互作用中具有不同的重要性，细胞色素、菌毛和分泌的黄素可能在电子转移中起关键作用[1，2]。学生将通过研究地质杆菌与锰和锰/铁氢氧化物的相互作用来阐明微生物还原锰羟基氧化物在控制钴命运中的作用；红土中的钴和锰呈正相关，而镍与锰结核中的锰氢氧化物中的二氧化锰呈正相关。将使用一系列最先进的微生物和地球化学技术来研究一套包含潜在矿石的微观世界。同步辐射通过确定所涉及的氧化还原过程以及有机和无机组分之间的空间关系，对于揭示这些过渡金属的行为机制至关重要。特别是，扫描透射式X射线显微镜(光束线I08，DLS)在40纳米尺度上提供元素分布、金属氧化状态和结构信息。通过测量C K边和MnL2.3、CoL2.3和FeL2，3边，可以确定微生物种类与不同微观世界产物的氧化状态的关系[3，4]。这将有助于更好地了解钴在环境中是如何循环的，并有助于优化浸出过程和选矿放大开发。

Laterites and Mn-nodules are potential new sources of Co that can be extracted by microbial processes. The key to exploiting these resources and optimising processing pathways is an understanding of the redox reactions at the microbial-Fe and Mn mineral interfaces. Determining the mechanisms of the interaction between microbes and Co-bearing Fe and Mn hydroxyoxide phases is critical to understanding the natural biogeochemical cycling of cobalt, and also the release of this technologically important metal from potential ores during bioprocessing. The Fe and Mn mineralogy of these, often poorly crystalline, ferruginous concentrations comprises the ferri- and mangano-hydroxyoxides with cobalt present as both Co(II) and Co(III). Dissimilatory Fe(III) and Mn(IV) reduction by microorganisms provides a pathway to extract Co from these sources; the controls on the electron transfer processes in the key microbial-mineral interactions of Mn is less well known than Fe, and that of Co and Ni are little studied. Extracellular polymeric substances including lipopolysaccharides are thought to have varying importance in microbial-mineral interactions, and cytochromes, pili and secreted flavins may play a key role in electron transfer [1,2].The student will elucidate the role of microbial reduction of Mn hydroxyoxides in controlling Co fate by examining the interaction between Geobacter species and Mn and Mn/Fe oxyhydroxides; Co and Mn are positively correlated in laterites while Ni correlates with MnO2 in Mn-hydroxides in Mn-nodules. A suite of microcosms containing potential ores will be studied using a range of state of the art microbial and geochemical techniques. Synchrotron radiation is crucial to exposing the mechanisms of behaviour of these transition metals by determining the redox process involved and the spatial relationship between the organic and inorganic components. In particular, scanning transmission X-ray microscopy (beamline I08, DLS) provides, at a scale of 40nm, elemental distributions, metal oxidation states and structural information. Measurement the C K-edge and Mn L2.3, Co L2.3 and Fe L2,3 edge will identify the relationship between microbial species and the oxidation states of the products of different microcosms [3,4]. This will lead to a better understanding of how Co is cycled in the environment, and also help optimise the leaching processes and mineral processing scale-up development.