孔雀石晶体层状空间结构及其插层硫化机理

Malachite is the most important copper oxide mineral and the main object in copper recovering. The most common process of copper recovering from malachite is sulfuration flotation. It has been widely demonstrated through experiments and industrial practices that the sulfuration reaction is very fast, and a large amount of sodium sulfide are consumed. Such phenomena can be hardly explained by the existing theories like sulfurating from surface to inner successively which are inconsistent with mixed control model. In the project, the layer structure of the malachite crystal was further confirmed and the intercalation sulfuration mechanism was proposed, which could help explain the current theory problems of sulfide flotation. So as to investigate its mechanism, malachite was selected as the main research object in this project, and the crystal cleavage planes and lattice parameters were obtained by structure refinement and the scanning electron microscope (STEM). The adsorption position and movement of sulfide ion on surface and interlayer were conducted by the time-of-flight secondary ion mass spectrometer (TOF SIMS). Subsequently, the experimental study of the adsorption thermodynamics and kinetics of sulfide ion was proceeded. The dynamics computational simulation of geometric and electronic structural properties of crystal surface and interlayer, and adsorption process and mechanism of sulfide ion on surface and interlayer were conducted using CASTEP, Dmol3 and cluster models. The process and essence of the sulfuration of copper oxide minerals such as malachite were revealed according to the acknowledge of crystal layer structure in malachite. The new theory of intercalation sulfuration mechanism model could be established. The theoretical foundation of the targeted regulation of flotation pulp and the efficient flotation separation of copper oxide ore were provided.

孔雀石是最主要的氧化铜矿物，是回收铜的主要对象之一，最常用的工艺是硫化浮选法。实践表明，孔雀石硫化速度很快，且消耗大量硫化钠，但现有的表面硫化理论或从表层到次层依次硫化的观点难以解释这些现象，与硫化过程的混合控制理论也不一致。本项目进一步证实孔雀石晶体存在层状结构，提出插层硫化的新机制，能够解释当前硫化浮选存在的理论问题。为探明其机理，本项目以孔雀石为主要研究对象，采用结构精修和扫描透射电子显微镜对晶体解理面和层状结构进行检测和确认；运用飞行时间二次离子质谱仪表征晶体表面和层间硫离子吸附位置和动向；进行硫离子吸附热力学和动力学试验研究；采用CASTEP、Dmol3及团簇方法对表面和层间电子结构性质、硫离子层间吸附过程及机制进行动力学计算模拟；从而弄清孔雀石晶体层状空间结构特征，形成插层硫化理论，揭示孔雀石等氧化铜矿硫化作用的形式和本质，为氧化铜矿浮选矿浆针对性调控及其高效选别提供理论依据。

孔雀石是最主要的氧化铜矿物，最常用的选矿回收工艺是硫化浮选法。但孔雀石硫化速度快且消耗大量硫化钠，之前的表面硫化理论难以解释这些现象，探究其原因和机理对提高孔雀石硫化效率和降低药耗具有重要意义。本项目进一步证实了孔雀石晶体存在层状结构，提出了插层硫化的新机制，能够解释当前硫化浮选存在的理论问题和实践现象。为探明其机理，本项目以孔雀石为主要研究对象，对其晶体解理面和层状结构进行了检测和确认；运用飞行时间二次离子质谱仪表征了晶体表面和层间硫离子吸附位置和动向；进行了硫离子吸附热力学和动力学试验研究；对表面和层间电子结构性质、硫离子层间吸附过程及机制进行了动力学计算模拟。得到的主要研究结论包括：世界不同地点的孔雀石具有相似晶面指数，可视化的晶体结构几乎相同，进一步确认了孔雀石晶体都具有明显的沿（-201）面的层状结构。孔雀石晶体中两个相邻层中的铜原子之间最小距离大于硫离子直径，晶体中羟基的存在及其平衡作用、同层之间的共价键作用、不同层间分子间作用力，共同维持了层状结构的稳定存在，给硫离子的层间硫化提供了空间结构和相互作用上的可能。采用ToF SIMS深剖质谱分析确认了孔雀石插层硫化的客观存在。动力学计算模拟结果也表明硫离子能够进入孔雀石晶体的层间。孔雀石硫化程度从表面到内层呈现降低趋势，在不同的内层深度含有不同的硫化物种。硫离子在孔雀石表层吸附与插层吸附的机制不同。孔雀石硫化的过程是表面和层间同步吸附硫离子的过程，是扩散控制的过程，进而实现了综合硫化的结果，强化了捕收剂的吸附稳定性。本项目的研究结果揭示了孔雀石晶体层状空间结构特征，形成了插层硫化新观点，明晰了孔雀石等氧化铜矿硫化作用的形式和本质，将对氧化铜矿的浮选回收具有理论指导作用，为浮选矿浆的针对性调控和实现矿物高效分离提供了理论依据。