常压下高级氧化-碱湿法预处理低品位微细浸染型原生金矿的机理研究

In order to effective extract gold from low grade microfine disseminated primary gold deposit by hydrometallurgical pretreatment in constant pressure. Improve the efficiency of dissolution and corrosion of gold wraps is the main means to strengthen pretreatment, and appropriate advanced oxidation process have an edge on strengthening pretreatment. Advanced oxidation process will have good prospect of application on strengthening pretreating low grade microfine disseminated primary gold deposit. Explore clearly the thermodynamic properties, chemical reaction kinetics of dissolution process and mechanism of strengthen pretreatment of advanced oxidation system of pyrite hydrometallurgy pretreatment, the alkaline leaching behavior of quartz under the condition of different ion concentration. Investigating the relationship between gold leaching rate of microfine disseminated primary gold and porosity factor, morphology, extent of corrosion and valence of elements of pyrite and quartz. The technology idea is through pyrite advanced oxidation process, quartz alkaline and leaching microfine disseminated primary gold deposit experiment, focused research the oxidizing ability between different advanced oxidation process, the valence changing mechanism of elements Fe and S, the surface corrosion rate mechanism in the process of quartz leaching, reduced the gold wrapped by pyrite and quartz in hydrometallurgical pretreatment process of microfine disseminated primary gold deposit, improved the gold leaching rate. Making effective extracting gold from low grade microfine disseminated primary gold deposit in constant pressure become reality, providing reference for the development and utilization of this type gold deposit.

为了在常压下通过湿法预处理有效回收低品位微细浸染型原生金矿中的金，强化预处理是提高金包裹物溶解和腐蚀效率的主要途径，合适的高级氧化体系具有强化预处理作用，高级氧化体系在强化低品位微细浸染型原生金矿预处理方面具有良好的应用前景。探清黄铁矿高级氧化体系反应热力学性质、溶解过程化学反应动力学规律和强化机理，石英在不同离子浓度下碱浸行为。考察微细浸染型金矿中金的浸出率与浸出渣中黄铁矿和石英表面孔隙率、形貌变化、溶蚀程度以及元素化合价的关系。技术思想是通过黄铁矿高级氧化和石英碱湿法预处理试验，微细浸染型金矿的浸出试验，着重从不同高级氧化技术对黄铁矿的氧化能力，氧化过程中铁、硫元素化合价的转变机理，石英碱浸过程中表面溶蚀速率和机理进行研究，减少微细浸染型金矿湿法预处理过程中黄铁矿和石英对金的包裹，提高后续过程中金的浸出率。实现常压下低品位微细浸染型原生金矿高效利用，为该类型金矿开发利用提供借鉴。

为了在常压下通过湿法预处理有效回收低品位微细浸染型原生金矿中的金，强化预处理是提高金包裹物溶解和腐蚀效率的主要途径，合适的高级氧化体系具有强化预处理作用，研究发现，基于SO4-∙和·OH的高级氧化体系在常温常压下能高效溶蚀黄铁矿，为后续浸金创造有利条件。过硫酸盐体系中温度对黄铁矿氧化浸出影响较大，APS溶液浸出7h时，70℃的浸出率要比30℃时提高了46.62%；70℃时过硫酸盐仅通过热激活就能产生SO4-∙氧化黄铁矿；常温下，需添加Fe2+以化学激活方式产生SO4-∙，nZVI(FeO)-APS高级氧化黄铁矿效果较明显，在0.5h氧化率分别为91.12%、82.95%；黄铁矿在浸出过程中表面形成蜂窝状孔洞，浸出过程符合1-2/3x-(1-x)2/3=kt动力学模型，受残留固体膜层扩散控制；过硫酸盐分解产生SO4-∙浸出黄铁矿在理论上完全可行，浸出过程中S元素最终以SO42-和HSO4-形式存在，而Fe元素最终以Fe2+和Fe3+形式存在。H2O2氧化过程中没有固相生成物，黄铁矿中Fe转化为Fe2+和Fe3+于溶液中，Fe2+与H2O2反应生成氧化性极强的∙OH，氧化过程中有H2SO4生成；黄铁矿主要被酸性H2O2、∙OH和Fe3+氧化，矿物中S最终转化为SO42-或HSO4-；酸性H2O2氧化法预处理后Fe浸出率为95.33%。在nZVI-APS体系中，黄铁矿氧化反应路径TS1→IC→TS2，其中TS1是该体系产生SO4-∙速控步；Fe2+与APS中S原子、O原子和O桥键均产生吸附，而O桥键上吸附成键最稳定；SO4-∙均能氧化黄铁矿中Fe和S，其中Fe是主要反应活性点。不同晶体缺陷载金黄铁矿稳定性顺序：As<载金黄铁矿<Co<Ni，即As取代在氧化预处理时更容易被氧化。溶液中难免离子NH4+、Fe2+对NaOH溶解石英均有促进作用；在NH4+-NaOH体系中，石英溶解符合化学控制收缩核动力学方程1-(1-α)1/3=kt，但表观活化能为12.02kJ/mol，在扩散控制范围内，表明石英在难免离子影响下NaOH溶解石英具有特殊性，推测是多元多相复杂体系；NaOH、NH4+-NaOH和Fe2+-NaOH体系与石英溶解路径TS1→IC→TS2，均为亲核加成-消除反应。研究成果为实现常温常压下高效预处理低品位微细浸染型原生金矿提供技术原型和理论依据。