机械活化—电位调控协同强化黄铜矿生物浸出动力学机制

Chalcopyrite is one of the most abundant and widespread copper-bearing minerals, accounting for approximately 70% of the Earth's copper. Although 20% of copper is produced through hydrometallurgy processes, the low leaching kinetics and low leaching rate of chalcopyrite limits the industrial application of chalcopyrite bioleaching. Many studies have shown that the leaching of chalcopyrite can be enhanced though mechanochemical activation or redox potential regulation. Electronic structure plays a key role on the leaching of chalcopyrite, however the reduction in particle size can affect the electronic structure of the solid. In order to find out the essence of mechanical activation pretreatment to improve chalcopyrite leaching rate, the physicochemical behavior under different mechanical activation conditions was first investigated in this study. The influence of mechanical activation on the electrochemical behavior of chalcopyrite was quantitatively analyzed by electrochemical test and electrochemical parameter solution. The mechanism of bioleaching of chalcopyrite enhanced by mechanical activation was investigated from the energy matching between the empty states of the oxidant and filled states of reductant and the leaching kinetic. A technique for enhancement of chalcopyrite bioleaching kinetics though mechanochemical activation and redox potential regulation was proposed.

黄铜矿是重要的铜矿资源，约占全球铜资源量的70%。目前，全球约有20%的铜是通过湿法冶金生产的，但由于黄铜矿生物浸出速度慢、浸出率低，从而限制了黄铜矿生物浸出的工业应用。许多研究结果表明，通过机械活化预处理或调控浸出液电位能显著提高黄铜矿的浸出率。电子结构对黄铜矿的浸出有重要影响，而颗粒大小的改变会影响固体的电子结构。因此，本项目以黄铜矿研究对象，研究其在不同机械活化条件下的物理化学行为，查明机械活化预处理提高黄铜矿浸出率的本质；通过电化学试验和电化学参数求解，定量分析机械活化预处理对黄铜矿电化学行为的影响；通过浸出试验和浸出动力学分析，从氧化剂非占据态与还原剂占据态能量匹配角度和动力学角度探究机械活化强化黄铜矿生物浸出的机制；通过机械活化条件—溶液电位—浸矿微生物的多因素优化调控，强化黄铜矿浸出动力学。

世界上20%的铜是通过湿法冶金生产，但黄铜矿浸出速度慢，浸出效率低。许多研究表明机械活化预处理可以提高黄铜矿浸出率。本文以黄铜矿为研究对象，研究其在不同机械活化条件，由机械能引起的矿物物理化学性质和内部晶体结构的变化，及其黄铜矿电化学和浸出行为影响规律，查明机械活化强化黄铜矿浸出机制。本文主要结论如下：.（1）机械活化后，黄铜矿粒度显著降低，D50由未活化时的10.28 μm 降至2.91 μm。XRD分析结果表明，活化黄铜矿衍射峰强度降低，衍射峰宽化，晶粒尺寸由1937 Å降至301 Å，而微观应变则由0 %变化至0.3486 %，晶胞体积进一步膨胀。.（2）机械活化与电位协同调控能明显提高黄铜矿浸出率，其中活化转速400 rpm黄铜矿在Fe3+=0.1mol/L体系浸出率是未活化黄铜矿的3.76倍，浸出渣中只存在黄铜矿和单质硫。黄铜矿在合适的电位范围浸出时可获得较高浸出率。浸出动力学结果表明机械活化能明显降低反应活化能，黄铜矿在Fe3+=0.1mol/L体系中活化能由90.98 kJ/mol降至62.83 kJ/mol。.（3）电化学试验表明：机械活化后黄铜矿氧化峰和还原峰电流均有不同程度增加，腐蚀电位减小，极化电阻降低，腐蚀电流和腐蚀速率增加，电荷转移电阻降低，活化后黄铜矿电子传递速度加快，电化学活性增强。.（4）Mott-Schottky曲线和XPS结果表明：机械活化预处理改变了黄铜矿能带结构，导带和价带位置发生正向移动，黄铜矿价带顶更接近Fe3+/Fe2+电对的Eredox值，意味着Fe3+能够从黄铜矿表面捕获电子被还原，即活化后黄铜矿能与Fe3+发生氧化还原反应。