印尼油砂热解过程中微量元素迁移规律的研究

Study on the Migration of Trace Elements in the Pyrolysis of Indonesian Oil Sand

采用逐级化学提取法对油砂中Li、V、Mn、Ni、Cu、Zn、Ga、Cd和Pb进行6种赋存状态的提取,分析各元素的赋存状态.利用电感耦合等离子体质谱仪测定油砂及半焦中9种元素的含量,分析元素在样品热解过程中的迁移规律.结果显示在6种赋存状态中9种重金属元素均有分布,同种油砂中不同元素的赋存形态存在一定的差异,Ga、Pb和Li均未出现在某一形态中突出赋存的情况,其余6种元素则存在在某一赋存状态占比较大的现象;热解实验显示,除Li外其他元素的迁移率都呈现出在500℃以下随温度升高不断增加,500℃到600℃之间放缓,在600℃以上再次快速增加的趋势.当热解温度为900℃时,9种微量元素的迁移率为40%~90%;Cd在油砂中富集程度较高,并且热解过程中迁移率可高达90%以上,对环境的潜在危害较大.

The sequential chemical extraction was used to extract and analyze six occurrence states of Li,V,Mn,Ni,Cu,Zn,Ga,Cd and Pb in oil sand. Inductively coupled plasma mass spectrometry was used to determine the contents of nine elements in oil sand and semi coke,so as to analyze the migration law of the elements in the pyrolysis process of samples. The results showed that nine heavy metal elements were distributed in the six occurrence states,and there were some differences in the occurrence fractions of different elements in the same kind of oil sand. Ga,Pb and Li did not occur in a prominent occurrence in a certain state,while the other six elements were prominent in a certain occurrence state. Pyrolysis experiments showed that the mobility of all elements except Li increased continuously below 500℃,slowed down between 500℃ and 600℃,and increased rapidly again above 600℃. When the pyrolysis temperature was 900℃,the mobilities of nine trace elements were 40% to 90%. The enrichment degree of Cd in oil sand was high,and Cd migration rate in the pyrolysis process could reach more than 90%,which was potentially harmful to the environment.