Silver-catalyzed bioleaching of enargite concentrate using moderately thermophilic microorganisms
Silver-catalyzed bioleaching of enargite concentrate using moderately thermophilic microorganisms
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DOI：
10.1016/j.hydromet.2018.03.014
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发表时间：
2018-05-01
期刊：
影响因子：
4.7
通讯作者：
Okib, Naoko
中科院分区：
文献类型：
--
作者：
Oyama, Keishi;Shimada, Kazuhiko;Okib, Naoko
在45℃条件下，采用中等嗜热嗜酸微生物的混合培养，研究了银(Ag)催化剂对辉绿岩(Cu3AsS4)精矿生物浸出的影响。添加Ag2S可以在抑制黄铁矿氧化的同时选择性地溶解铜：在最高Ag2S浓度为0.04%时，铜的回收率达到96%，而铁的溶解被抑制到第72天只有29%。热力学计算、液/固分析和动力学研究的总体结果表明，银催化微生物浸出辉铜矿精矿是通过形成至少两种次生产物(辉铜矿，Cu2S；三银硫化砷，Ag3AsS4)进行的：添加Ag2S作为银催化剂，热力学和微生物方面有助于降低细菌浸出过程中溶液的氧化还原电位，从而满足E-ox(Cu2S)和lt；Eh<；E-c(Ag+)通过形成辉铜矿中间体来促进辉铜矿溶解的作用。硫化三银砷及其中间层(Cu，Ag)(3AsS4)的形成表明辉石晶格中的铜离子逐渐被银取代。这种二次产物没有施加限速步骤，因为银催化的生物浸出被证明是由表面化学反应控制的，而不是像没有Ag2S时那样通过产物膜扩散。
Effect of silver (Ag) catalyst in bioleaching of enargite (Cu3AsS4) concentrate was studied using mixed cultures of moderately thermophilic acidophilic microorganisms at 45 degrees C. Addition of Ag2S enabled selective Cu dissolution from enargite while suppressing pyrite oxidation: At the highest Ag2S concentration of 0.04%, Cu recovery reached 96% while Fe dissolution was suppressed to reach only 29% by day 72. Overall results from thermodynamic calculation, liquid/solid analyses and kinetic study suggested that Ag-catalyzed bioleaching of enargite concentrate proceeds via formation of at least two types of secondary products (chalcocite, Cu2S; trisilver arsenic sulfide, Ag3AsS4): Addition of Ag2S as Ag catalyst thermodynamically and microbiologically contributed to lowering solution redox potentials during bioleaching, consequently satisfying E-ox (Cu2S) < Eh < E-c (Ag+) to enhance enargite dissolution via formation of chalcocite intermediate. Formation of trisilver arsenic sulfide and its intermediate layer (Cu,Ag)(3)AsS4 indicated that Cu ion in the enargite lattice is gradually substituted with Ag. Such secondary products did not impose a rate-limiting step, since the Ag-catalyzed bioleaching was shown to be controlled by a chemical surface reaction, rather than diffusion through product film which was the case in the absence of Ag2S.