活性焦制备过程中汞的迁移研究

为研究工业活性焦生产过程中汞的迁移情况,使用实验室设备模拟工业制备活性焦的工艺过程制备活性焦样品,并以冷原子吸收法为基本原理的测汞仪对制备活性焦的原料煤、炭化样品和活性焦样品的汞含量进行测定,计算制备过程中汞的迁移量。结果表明:制备活性焦的原料煤中汞含量为42. 4 ng/g,制备过程的中间产物炭化样品(TH)的汞含量仅为1. 0 ng/g,活性焦样品(HXJ)的汞含量仅为0. 8 ng/g。原料煤中汞的赋存形态主要以共价化合物的无机盐和一些腐植酸中的有机汞存在,这些汞化合物的分解温度在350℃左右,而炭化温度可达到650℃,此时原料煤中大部分汞的化合物都已分解并以零价汞蒸汽的形式逸散到大气中。炭化过程是活性焦制备过程中汞迁移逸散量最大的阶段,原料中97. 6%的汞在此阶段逸散到空气中。在工业化制备活性焦过程中,对炭化阶段产生的尾气进行脱汞处理十分必要。 In order to study the migration of mercury in the process of industrial producing activated coke,the laboratory equipment that can simulate the process of industrial preparing activated coke was used to prepare the activated coke sample. And the mercury content of raw coal,carbonized samples and activated coke samples was determined by the mercury detector based on cold atomic absorption spectrometry and the amount of mercury that migrated in the preparing process was calculated. The results show that the mercury content of the raw coal for preparing activated coke is 42.4 ng/g,the mercury content of the intermediate carbonized sample (TH) is 1.0 ng/g and that of the activated coke sample (HXJ) is only 0.8 ng/g. The results show that the form of mercury in raw coal is mainly composed of inorganic salts of covalent compounds and organic mercury in some humic acids,and the decomposition temperature of these mercury compounds is around 350 ℃. While the carbonization temperature can reach 650 ℃,the most of the mercury compounds in the raw coal have been decomposed and escaped to the atmosphere in the form of zero-valent mercury vapor. The carbonization process in preparing activated coke is the largest stage of mercury migration and evaporation,and 97.6% of the mercury in the raw coal escapes into the air at this stage. In the industrialized process of preparing activated coke,it is necessary to control and remove the mercury emission in the exhaust gas generated by carbonization stage