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煤中稀土元素研究现状及展望

Research status and prospect of rare earth elements in coal

  • 摘要: 稀土作为战略资源广泛应用于国防工业和高科技领域,我国作为稀土生产和出口大国,传统稀土储量日益减少。因此扩大我国稀土资源储量具有重要的经济价值和战略意义。稀土元素在特定的地质条件下可以在煤中富集,甚至达到工业品位。近年来,煤地质学家对煤中稀土元素开展了大量研究工作,取得了丰硕的研究成果。实测了新疆、鄂尔多斯、青海木里、宁夏鸳鸯湖等地125个样品中稀土元素含量,并结合前人资料对煤中稀土元素分布特征、赋存状态、富集影响因素、燃烧过程中迁移规律以及粉煤灰中稀土元素赋存状态和分离提取方法进行总结,为煤和粉煤灰中稀土元素的资源化利用提供理论依据。我国煤中稀土元素含量远高于美国煤中稀土元素含量,二连盆地-海拉尔盆地和西南川滇桂地区是我国两大煤中稀土元素成矿带。稀土元素在煤中主要以稀土矿物、有机化合物以及离子吸附的形式存在。煤中稀土元素的富集可能是不同时期沉积物源、搬运介质、沉积环境、风化淋滤和岩浆活动相互叠加的结果。煤燃烧过程中,稀土元素作为非挥发性元素在飞灰和底灰中进一步富集。粉煤灰中稀土元素赋存在玻璃体、含稀土矿物和非晶碳中。不同类型和来源的粉煤灰可能适用于不同的物理分选和化学提取方法。我国作为煤炭生产和使用大国,从煤和粉煤灰中提取稀土元素具有天然优势。因此,加强煤及燃烧产物中稀土元素提取实验研究,建立工业化提取稀土元素的实验工厂具有良好的发展前景。

     

    Abstract: As a strategic resource, rare earths are widely used in the defense industry and high-tech fields. As a major producer and exporter of rare earths, traditional rare earth resource of China has been declining. Therefore, expanding China's reserves of rare earth resources has important economic value and strategic significance. Rare earth elements can be enriched in coal under specific geological conditions, and even reach industrial grades. In recent years, coal geologists have carried out lots of researches on rare earth elements in coal and have made great progress. In this paper, the content of rare earth elements in 125 samples from Ordos in Xinjiang, Muli in Qinghai, Yuanyang Lake in Ningxia and other places were measured,and combined with previous data, the distribution characteristics of rare earth elements in coal, occurrence state, enrichment factors, and migration laws during combustion were measured, and the separation and extraction methods of rare earth elements in fly ash were summarized, which provides theoretical basis for the resource utilization of rare earth elements in coal and coal fly ash. The content of rare earth elements in coal in China is much higher than that in America. The Erlian-Hailaer basin and southwestern Sichuan-Yunnan-Guangxi region are the two metallogenic belts of rare earth deposits in coal. Rare earth elements mainly exist in coal in the form of rare earth minerals, organic compounds and adsorbed ions. The enrichment of rare earth elements in coal may be the result of superposition of sediment sources, transport medium, sedimentary environments, weathering leaching and magmatic activities in different periods. During coal combustion, rare earth elements, as nonvolatile elements, are further enriched in fly ash and bottom ash. Rare earth elements in coal fly ash are present in glass, REY-bearing minerals and amorphous carbon. Different types and sources of coal fly ash may be suitable for different methods of physical separation and chemical extraction. As major coal producer and consumer in the world, China has natural advantages in extracting rare earth elements from coal and fly ash. Therefore, enhancing study on the extraction of rare earth elements from coal and combustion products, and building industrial extraction of rare earth elements of the pilot plant have prospective prospect.

     

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