煤及其燃烧产物飞灰和底灰中稀土元素地球化学特征及集散规律

采用ICP—MS法测试了褐煤、肥煤和无烟煤以及在不同燃烧条件下获取的飞灰、底灰等29个样品的稀土元素含量;分析了稀土元素地球化学特征。结果表明,不同煤种的稀土元素含量不同,相同煤种在不同燃烧条件下获取的飞灰、底灰中的稀土元素含量也不同;褐煤、肥煤、无烟煤及其燃煤产物飞灰、底灰的稀土元素分布模式呈左高右低的宽缓的“V”型曲线;Eu存在明显负异常。研究了燃煤过程中稀土元素的分布及集散规律,稀土元素在飞灰、底灰中的含量比原煤有明显提高,其增加幅度为几倍至20多倍不等,表明煤炭燃烧后稀土元素在飞灰、底灰中进一步聚集;飞灰和底灰中稀土元素含量、飞灰和底灰对煤的稀土元素含量比和富集因子以及飞灰对底灰的稀土元素含量比和富集因子等,不仅与原煤中稀土元素有直接关系,而且还受锅炉燃烧方式、燃烧温度(炉温)等人为因素的影响。

Geochemical feature and laws of concentration and dispersion of rare earth elements between coals and their fly and bottom ashes

The contents of rare earth elements(REE)of 29samples in lignite,fatty coal,anthracite and their fly and bottom ashes in different combustion condition are determined by ICP-MS method,and geochemical feature of REE are analyzed.The results show th at different coals have different contents of REE,and the fly and bottom ashes produced in different combustion condition at the same coal rank have different contents of REE,too.The REE distribution patterns of lignit e,fatty coal,anthracite and all fly and bottom ashes are characterized b y a "V-shape"curve with obviously Eu negative anomaly and with enrichment of LREE and d eficiency of HREE.The distribution and laws of concentration and dispersion of REE during coal combustion process are studied.It i s found that the contents of REE in fly and bottom ashes are several times to twenty times higher than those of their raw coals,respectively.It manifests t hat the contents of REE are concentra ted in fly and bottom ashes after coal combustion.The contents of REE in fly and bottom ashes,the REE contents r atios and concentration factor of fly and bottom ashes to raw coals,and the REE contents ratios and concentrati on factor of fly ashes to bottom ashes not only have a direct relationship with the contents of REE in raw coals,but a lso are influenced by the man-made factors,such as the combustion meth od of boiler,combustion temperatur e(the temperature in boiler),and so on.