高硫煤中有害元素组U-V-Cr-Mo的富集机理及协同脱除研究

High-sulfur coal in China accounts for a large proportion. With intensive mining at present, the superficial layer low-sulfur coal resources are now getting depleted, so the high-sulfur coal will have to be mined. However, high-sulfur coal contains high concentration of toxic trace elements. The applicant in the early stage found that toxic trace elements assemblage U-V-Cr-Mo in high-sulfur coal from Southwest China are enriched, but their enrichment mechanism is not clear, and after industrial coal preparation, the toxic elements assemble still cannot be effectively removed, therefore, it has great potential of environmental hazards. According to the scientific problem, this study selected the typical high-sulfur coal from the northern and southwestern China as the research object: (1) The distribution and occurrence characteristics of toxic elements U, V, Cr, and Mo in typical high-sulfur coal from northern and southwestern China will be contrastively analyzed for drawing a general rule, and reveal its enrichment mechanism; (2) Based on the leaching experiment, the ability of U, V, Cr, Mo and other toxic elements in high-sulfur coal invasion into the environment and the geochemical control factors will be discussed; (3) Based on the different coal preparation methods, the partitioning of toxic elements assemble U, V, Cr, Mo in high-sulfur coal will be discussed, and combined with chemical method, microorganism method, and organic extraction separation, looking for these toxic elements of synergistic removal method. The research results try to provide scientific basis for the effective utilization of high-sulfur coal and promote the development of clean coal technology.

我国高硫煤资源占有较大的比重，随着目前开采强度的加大，浅部低硫煤炭资源即将枯竭，将不得不开采深部高硫煤。然而高硫煤也伴生高含量的有害微量元素，申请人前期研究发现西南高硫煤中一般富集有害微量元素组U-V-Cr-Mo，其富集机理不清楚，而且进行工业化洗选之后，该有害元素组仍不能有效脱除，存在极大环境危害潜势。针对此科学问题，本项目以华北与西南典型高硫煤为研究对象：（1）对比分析华北与西南典型高硫煤中有害元素U、V、Cr、Mo的分布赋存特征，得出一般性规律，揭示其富集机理；（2）基于淋滤实验等，探讨高硫煤中U、V、Cr、Mo等有害元素侵入环境的能力和地球化学控制因素；（3）基于不同选煤方法的洗选实验，揭示高硫煤中有害元素组U、V、Cr、Mo的洗选分配规律，并结合化学法、微生物法和有机萃取分离等手段，寻找这些有害元素的协同脱除方法。研究成果试图为高硫煤的有效利用提供科学依据，推动洁净煤技术的发展。

项目基于西南地区贵州和云南高硫煤样的洗选、淋滤和热解等实验，以及TEM、SEM和FTIR等分析技术，研究了高硫煤中有害元素组U-V-Cr-Mo的富集机理及协同脱除，发表论文5篇，其中SCI 收录4篇，出版专著1部，达到了预期的成果。（1）查明了高硫煤中有害元素组U-V-Cr-Mo的赋存特征和富集机理。研究发现中国富铀高硫煤主要分布在华南聚煤区，富铀高硫煤一般具有富集V-Cr-Mo-U元素组合的特征，高硫煤中含铀矿物主要包括微细粒或者纳米级锐钛矿、铀钛矿和黏土矿物、黄铁矿等矿物中，V和Mo元素主要以吸附态、或者赋存在碳酸盐矿物、硫化物矿物和铝硅酸盐矿物中，Cr和U主要以有机态为主，部分赋存在矿物中。高硫煤中V、Cr、Mo、U的富集是受到了富V-Cr-Mo-U的热液流体和火山灰影响。（2）揭示了高硫煤中有害元素组U-V-Cr-Mo侵入环境的能力和地球化学控制。在酸介质下，高硫煤中V元素的释放率最低，Cr、Mo、U的释放率相对较高， V、Cr、Mo和U元素在400℃到1000℃的热解温度下含量差异不大，当热解温度升至1200℃，煤中有害元素在含量大幅度降低，V和Cr迁移率在35%左右，Mo的迁移率20%左右，U元素的迁移率达到了50%以上。（3）探索了高硫煤中有害元素组U-V-Cr-Mo的洗选分配规律及其协同脱除机理。基于不同的选煤方法研究发现，重选和浮选对V、Cr、Mo和U元素的协同脱除效果较差，磁选方法相对较好，除Mo元素外，V、Cr和U元素的脱除率高于使用重选和浮选。高硫煤中V、Cr、Mo和U元素的深度脱除与其赋存状态和富集成因有关，由于V、Cr、Mo和U形成受到同生热液影响，并赋存在同生微细粒矿物和有机质中，导致了高硫煤中V、Cr、Mo和U元素的脱除存在困难，磁选可以有效分离煤中有机质和微细粒矿物，因此脱除效果优于重选和浮选。