煤型锗矿床中锗的赋存状态及机理研究

As a kind of strategic resource, germanium is extracted primarily from coal-hosted Ge ore deposits. The Wulantuga (Inner Mongolia) and Lincang (Yunnan Province) high-Ge coal deposits are the only two Ge ore deposits in China that can be utilized industrially and are of substantial scientific and economic value. The organic affinity of germanium in the Ge-rich coals has been widely recognized, but the mode of occurrence of Ge in the organic matter and its mechanism remain unclear. In this project, the object of study is germanium in the Wulantuga and Lincang Ge ore deposits. A series of advanced techniques/methods will be applied, including Inductively Coupled Plasma Mass Spectrometry (ICP-MS), Electron Probe Microanalysis (EPMA), Fourier Transform Infrared Spectroscopy (FTIR), Raman Spectra (Raman), Nuclear Magnetic Resonance (NMR), and mineralization simulation. By using the knowledge of coal petrology, coal geochemistry, and coal structure chemistry, this project aims to investigate the distribution patterns of abnormally enriched trace elements (especially Ge) in the macerals of Ge-rich coals, the bonds between germanium and organic matter, and the aqueous media conditions for germanium transfer to organics during peat accumulation and the diagenetic process. By analyzing the factors that influencing the mode of occurrence of Ge in the transfer process from solution to organics and the change of the Ge occurrence in the diagenetic process, the mode of occurrence of germanium and its mechanism for the coal-hosted Ge ore deposits are expected to be disclosed. This study can not only enrich the knowledge on the coal-hosted Ge ore deposits, but also provide scientific support for the extraction and utilization of Ge from coals.

锗作为一种战略资源，主要提取自煤型锗矿床。内蒙古乌兰图噶和云南临沧高锗煤矿床是我国仅有的两处可用于工业开发的煤型锗矿床，具有重要的科学和经济价值。高锗煤中的锗具有显著的有机亲和性是学界共识，但锗在有机质中的赋存状态及其机理尚不明确。本项目以乌兰图噶和临沧锗矿床中的锗为研究对象，借助电感耦合等离子体质谱、电子探针、红外光谱、拉曼光谱、核磁共振和矿化模拟等手段，充分运用煤岩学、煤地球化学和煤结构化学的理论，深入研究乌兰图噶和临沧锗矿床中锗等异常富集微量元素在高锗煤显微组分中的分布规律，确定锗与有机质的结合方式，推演泥炭堆积和成岩过程中锗与有机质结合的有利介质条件。通过分析锗从溶液向有机质转移的过程中影响锗赋存状态转变的因素，以及锗的赋存状态在成岩过程中的演变，揭示煤型锗矿床中锗的赋存状态及机理。本项目的研究不仅可以丰富煤型锗矿床的理论知识，还可以为指导锗的提取利用提供科学依据。

内蒙古乌兰图嘎和云南临沧煤型锗矿床对我国锗的战略储备和资源安全至关重要。煤型锗矿床中锗的有机亲和性广为人知，但其具体结合方式尚不明确，而绿色高效开发利用煤型锗矿床的关键就在于查明富锗煤中关键元素的赋存状态及其机理。本项目结合谱学实验和密度泛函理论计算，对煤型锗矿床中异常富集的锗及伴生元素钨的赋存状态及机理开展了系统研究。取得以下成果：（1）发现HCl-HF处理可显著脱除富锗煤中富集的Ge、W等有机亲和微量元素，同时在一定程度上破坏富锗煤有机质的结构。通过精细研磨、酸处理、浮沉实验获得富锗煤的腐植组样品，采用13C-NMR和KBr-FTIR半定量分析对比HCl-HF处理前后的富锗煤腐植组的结构差异，圈定富锗煤中与Ge富集有关的官能团为酚羟基结构。（2）考察富锗煤中Ge与羟基官能团之间的相互作用，研究了五种模型分子（邻苯二酚、苯酚、乙醇、乙酸和苯甲酸）形成Ge-O配合物的反应路径和稳定结构，发现酚羟基具有更强的反应活性。理论计算结果表明酚羟基对Ge的固定具有重要作用，从煤结构的角度揭示了煤型锗矿床中Ge的有机结合态的机理。（3）分析富锗煤中W的原子化学环境，对比研究Ge-O和W-O配位结构的差异。与Ge相比，由于整体上结合能更强，W可与羟基结合形成更为稳定的配合物。对于乙酸或苯甲酸，W倾向与3个分子结合形成变形八面体的W-O饱和配位结构，而Ge则倾向与4个分子结合形成四面体的Ge-O饱和配位结构。（4）从Ge-O和W-O配体的结构和成因推演煤型锗矿床中Ge和W的固定机制，即羟基官能团中的H解离后使O得以暴露，进而与碱性含N2热液中的Ge、W结合形成Ge-O和W-O配位结构。根据Ge和W微观尺度的赋存状态及机理，提出了煤型锗矿床中战略金属元素成矿的“形成—再分布”两阶段演化模式。