宁夏灵武煤热解过程中稀土元素配分规律及地球化学特征

Distribution pattern and geochemical characteristics of rare earth elements in Ningxia Lingwu coal during pyrolysis

采制宁夏灵武煤样,在1 000℃/min升温速度下对煤样进行不同终温(300,400,500,600,700,800,900℃)的热解制取半焦样;采用ICP-MS法测试煤样及其热解半焦样中稀土元素的含量,并对半焦样中稀土元素地球化学参数进行计算、分析.结果表明:宁夏灵武煤中稀土元素丰度不高,其中轻稀土元素,重稀土元素,Sc,Y的质量分数分别为29.731×10-6,3.402×10-6,2.570×10-6,5.690×10-6;热解半焦中稀土元素含量随热解终温的升高而升高,稀土元素在半焦中呈富集趋势,但轻、重稀土元素的富集程度不同;原煤样与热解半焦样中稀土元素分布模式均表现为趋势相似的由左向右先陡降后平缓的曲线,原煤样为Eu负异常的V型曲线,热解半焦样的Eu负异常不明显,Ce负异常明显,说明轻稀土元素分馏程度较高,重稀土元素分馏程度较低.

Seven char samples were derived from Ningxia Lingwu coal after pyrolysis with vari ous temperatures （300, 400, 500, 600, 700, 800 and 900 ℃） at heating rate of 1000 ℃/min. The contents of rare earth elements in coal and char samples were determined by ICP-MS meth- od, and the geochemical parameters of rare earth elements in chars were calculated and ana- lyzed. The results show that the abundance value of rare earth elements in Ningxia Lingwu coal is low, in which the mass fraction of light rare earth element, heavy rare earth element, Sc and Yare 29. 731×10- 6, 3. 402×10-6, 2. 570×10- 6 and 5. 690×10- 6 respectively. Though the contents of rare earth elements in chars increase and enrich with the uprising of pyrolysis temperature, the enrichment degree of light rare earth element and heavy rare earth element are different. Both the rare earth element distribution pattern of coal and char samples first decrease sharply and then become flat. Compared with the negative Eu anomaly with V-type curve in coal samples, char samples show negative Ce anomaly and unconspicuous negative Eu anomaly, suggesting that the fractional degree of light rare earth element is higher than that of heavy rare earth element.