煤、煤泥和煤矸石燃烧过程锂镓稀土元素的迁移规律

Migration of lithium,gallium and rare earth elements in coal,coal slime,and coal gangue during combustion

掌握煤中伴生有价微量元素在燃烧过程的迁移规律,对伴生元素的利用意义重大。选取4种高铝煤炭、1种煤泥和2种煤矸石等不同组成特性的样品为研究对象,采用逐级化学提取方法分析了锂(Li)、镓(Ga)和稀土(REE)在原料中的赋存形态,考察了以上元素在300~1100℃燃烧过程逸出情况和在燃烧灰中的富集行为,探讨了元素迁移规律与原料组成特性的关联。结果表明,Li、Ga和REE在7种样品中的赋存形态均以硅酸盐态为主,在燃烧过程的逸出率有与原料灰分呈负相关、与挥发分和含碳量呈正相关的趋势。以上元素在灰中均发生了不同程度的富集,REE的富集倍数高于Li和Ga。原料中微量元素含量和挥发分越高、灰分越低,同等燃烧条件下所得灰中微量元素的含量就越高。

Mastering the migration of valuable rare elements in coal during combustion is of great significance to theutilization of valuable elements in coal. Four coal samples with high aluminum content, coal slime, and two coalgangue samples were used in this work. The combine form of lithium(Li), gallium(Ga) and rare earth elements(REE) in these samples was analyzed using a stepwise chemical extraction method. We investigated the escape ofLi, Ga, and REE during coal combustion between 300 and 1100℃ and their enrichment behavior in ash. Thecorrelation between migration of rare elements and composition characteristics of coal samples was also discussed.The results showed that Li, Ga and REE in these coal samples were mainly in form of silicate. The escape ratio ofthese elements during coal combustion was negatively correlated with the ash content in coal, and positivelycorrelated with volatile matter and carbon content. These elements are concentrated in different degrees in ash, andthe enrichment efficiency of REE is higher than that of Li and Ga. The higher the content and volatile content of trace elements in the raw materials and the lower the ash content, the higher the content of trace elements in the ashobtained under the same combustion conditions.