Environmental Technology, Wageningen University, Wageningen, The Netherlands.
Environ Sci Technol. 2011 Aug 1;45(15):6316-21. doi: 10.1021/es200676z. Epub 2011 Jul 13.
Gold is commonly liberated from sulfide minerals by chemical and biological oxidation. Although these technologies are successful, they are costly and produce acidic waste streams. Removal of mineral-sulfur to overcome the mineralogical barrier could also be done by bioreduction, producing hydrogen sulfide (H(2)S). To make the sulfur within these minerals available for bioreduction, the use of partial bio-oxidation as a pretreatment to oxidize the sulfides to elemental sulfur was investigated in gas lift loop reactor experiments. Experiments at 35 °C using a refractory concentrate showed that at pH 2 arsenopyrite is preferentially partially oxidized over pyrite and that elemental sulfur can be subsequently converted into H(2)S at pH 5 via bioreduction using H(2) gas. A single partial bio-oxidation/bioreduction treatment increased the gold recovery of the concentrate from 6% to 39%. As elemental sulfur seems to inhibit further oxidation by covering the mineral surface, several treatments may be required to reach a gold recovery >90%. Depending on the number of treatments this method could be an interesting alternative to bio-oxidation.
金通常通过化学和生物氧化从硫化物矿物中释放出来。虽然这些技术是成功的，但它们成本高昂，且会产生酸性废水。通过生物还原去除矿物硫以克服矿物学障碍，也可以产生硫化氢 (H(2)S)。为了使这些矿物中的硫可用于生物还原，在气体升力环式反应器实验中研究了将部分生物氧化作为预处理来将硫化物氧化为元素硫的方法。在 35°C 下使用难熔精矿进行的实验表明，在 pH 值为 2 时，砷黝铜矿优先于黄铁矿进行部分氧化，并且可以通过使用 H(2)气体在 pH 值为 5 下将元素硫进一步还原成 H(2)S。单次部分生物氧化/生物还原处理将精矿的金回收率从 6%提高到 39%。由于元素硫似乎通过覆盖矿物表面来抑制进一步氧化，因此可能需要多次处理才能达到金回收率>90%。根据处理次数的不同，该方法可能是生物氧化的一种有趣替代方法。
