Ge extraction from gasification fly ash

Water-soluble germanium species (GeS2 GeS and hexagonal-GeO2) are generated during coal gasilication and retained in fly ash. This fact together with the high market value of this element and the relatively high content,, in the fly ashes of the Puertollano Integrated Gasification in Combined Cycle (IGCC) plant directed our research towards the development of an extraction process for this element. Major objectives of this research was to find a low cost and environmentally suitable process, several water based extraction tests were carried out using different Puertollano IGCC fly ash samples. under different temperatures. water/fly ash ratios, and extraction times. High Ge extraction yields (up to 84%) were obtained at room temperature (25 degrees C) but also high proportions of other trace elements (impurities) were simultaneously extracted. Increasing the extraction temperature to 50.90 and 150 degrees C. Ge extraction yields were kept at similar levels, while reducing the content of impurities, the water/fly ash ratio and extraction time, The experimented data point out the influence of chloride. calcium and sulphide dissolutions on the Ge extraction. (c) 2004 Elsevier Ltd. All rights reserved.