X-ray absorption near edge structure (XANES) spectroscopy analysis of the limonites used found that between 3.1 and 8.0% of the total chromium in the three limonite samples used in experiments was present in the raw materials as Cr (VI). Further investigations found this to be due to the release of Cr (VI) in the acidic liquors. Bioleaching experiments carried out in laboratory-scale reactors using limonites from a laterite mine in New Caledonia found that solid densities of ∼10% w/v resulted in complete inhibition of iron reduction by acidophiles, which is a critical reaction in the reductive dissolution process. However, there are also reports that the more oxidised and more biotoxic form of this metal may be present in some limonites, formed by the oxidation of Cr (III) by manganese (IV) oxides. Chromium-bearing minerals, such as chromite, where the metal is present as Cr (III), are widespread in laterite deposits. ![]() Limonite bioprocessing is an emerging technology that often uses acidophilic prokaryotes to catalyse the oxidation of zero-valent sulphur coupled to the reduction of Fe (III) and Mn (IV) minerals, resulting in the release of target metals. There is currently considerable demand for these transition metals, and this is projected to continue to increase (alongside their commodity values) during the next few decades, due in the most part to their use in battery and renewable technologies. Limonitic layers of the regolith, which are often stockpiled as waste materials at laterite mines, commonly contain significant concentrations of valuable base metals, such as nickel, cobalt, and manganese. 4Health and Life Sciences, Coventry University, Coventry, United Kingdom.3Diamond Light Source, Didcot, United Kingdom.2Natural History Museum, London, United Kingdom.1School of Natural Sciences, Bangor University, Bangor, United Kingdom. ![]() Herrington 2, Giannantonio Cibin 3 and D. Ana Laura Santos 1*, Agnieszka Dybowska 2, Paul F.
0 Comments
Leave a Reply. |
AuthorWrite something about yourself. No need to be fancy, just an overview. ArchivesCategories |