脉石矿物对黄铜矿微生物浸出体系的影响规律和机理

There are few studies on the effects of gangue minerals on the bacterial leaching for copper, and the efficiency of bacterial leaching is low recently. Aiming at these problems, the influence mechanism and law of the gangue minerals on bacterial leaching of chalcopyrite are investigated, based on the characteristics of the typical gangue minerals associated with chalcopyrite and multiphase system characteristics of bacteria- mineral- stripping ion. At first, the changes of pH value, redox potential, bacterial growth, and copper extraction of leaching solution with increasing of leaching time are analyzed under the effects of gangue minerals. The influence rules of gangue minerals on the bacterial leaching of chalcopyrite are revealed. And then, the experiment of gangue minerals dissolution in the leaching system is conducted. The tpye, concentraction and kinetic characteristics of dissolved ions under the biochemical action of leaching system are studied. The law and mechanism of the dissolving of gangue minerals in the bacterial leaching system are revealed. At last, the effects of coexisting ions on the bacterial life activities are studied by the ways of SEM, IR, Zeta, and so on. The effect mechansim is revealed through the studying on the change of the cell structure, morphology, functional groups and surface potential of bacteria caused by coexisting ions. This research can get the restrictive factors of gangue minerals on the bacterial leaching system and control the leaching velocity and leaching efficiency effectively. At the same time, the research results may provide scientific basis and technical support for the study of gangue minerals behavior law in bacterial leaching of other ore and enriching the basic theory of regulating bacterial leaching process.

针对脉石矿物对微生物浸出体系影响研究鲜见的现状和生物浸矿效率低的问题，结合黄铜矿共伴生典型脉石矿物的特性和细菌-矿物-溶出离子多相体系特征，进行脉石矿物对细菌浸出黄铜矿影响规律和机理研究。通过不同因素条件下脉石矿物对浸出体系pH、氧化还原电位、细菌生长、铜浸出率随浸出时间变化的影响研究，揭示脉石矿物对黄铜矿细菌浸出体系影响规律；进行脉石矿物在浸出体系溶出试验，研究其在浸出体系中溶出离子种类、浓度和动力学特征，揭示脉石矿物在生物化学协同作用下离子溶出规律和机理；借助扫描电镜、红外光谱、表面电位等测试手段，研究共存溶出阴阳离子对细菌生命活动的影响，从细菌细胞结构、形态、功能基团、表面电位等方面揭示脉石矿物溶出离子多元体系耦合作用的机制。通过研究，将有效解决调控细菌浸矿速度和浸出率的科学问题，为脉石矿物在其它矿石微生物浸出过程中行为规律研究和丰富调控微生物浸矿过程基础理论提供科学依据和技术支撑。

微生物浸矿技术有利于资源综合利用和环境保护，其应用研究已成为复杂难选矿、尾矿、废石等资源化利用研究的热点。本项目针对目前国内外在脉石矿物对微生物浸铜体系影响和机制方面研究尚缺的问题，选择与黄铜矿共伴生的典型脉石矿物：石英、绢云母、白云石、磷灰石、萤石作为研究对象，首先研究了脉石矿物对黄铜矿微生物浸出体系的影响规律，进而对脉石矿物在微生物浸出体系中的溶出特征和机理进行了研究，最后研究了脉石矿物溶出离子对细菌活性和铜浸出率的影响。研究发现，脉石矿物的质量浓度与粒度是影响铜浸出效果的主要因素，在粒度相同时，单一脉石矿物在适宜浓度下促进黄铜矿微生物浸出的规律是：石英(5.0%)>白云石(0.3%)>绢云母(5.0%)>空白值>磷灰石(0.5%)>萤石(0.1%)，脉石矿物与At.f菌吸附作用后表面电位变化、浸渣中生成的钝化物不同是导致不同脉石矿物对铜浸出效果影响差异的原因。研究得出了脉石矿物在At.f菌浸出黄铜矿体系的溶出特征：浸出48天时总硅、Al3+、Mg2+、F-、PO43-的溶出率分别为0.14%、1.23%、43.47%、3.23%、2.48%，明显高于单独酸浸条件下的溶出率，说明脉石矿物在微生物浸铜体系中的溶出受微生物作用明显强于化学作用；脉石矿物溶出顺序和离子溶出率呈一致关系，均为白云石>萤石>磷灰石>绢云母>石英；溶出动力学研究发现，石英和绢云母溶出硅、Al3+动力学可用收缩核模型中内扩散模型解释，而磷灰石溶出PO43-可采用孔隙型颗粒模型中孔隙扩散模型来描述；从矿物晶格能、可溶性，细菌对矿物的选择性吸附角度分析了不同脉石矿物溶出规律的差异，并采用SEM-EDS、红外光谱和表面电位等手段，揭示了脉石矿物在黄铜矿微生物浸出体系的溶出机理。研究获得了溶出离子对培养体系和浸出体系中细菌氧化活性和铜浸出率的影响规律，离子对At.f菌氧化活性的影响大小顺序依次为Mg2+、Al3+、K+、Ca2+；对铜浸出率影响大小顺序为15g/L铝离子、15g/L镁离子、1g/L钾离子、0.1g/L钙离子，这些离子作用下48天时铜浸出率分别为71.39%、59.01%、57.87%、47.30%；从黄铜矿浸出前后物相、形貌、电位及官能基团的变化等分析了不同离子胁迫对黄铜矿微生物浸出的影响机制。研究成果揭示了脉石矿物在黄铜矿微生物浸出过程中的影响规律，为改善铜浸出效果提供了理论依据。