科研之友
微信
新浪微博
Facebook
分享链接
摘要
1,1,1-Trichloro-2,2-bi(4-chlorophenyl) ethane (DDT) pesticide that has been extensively used in agriculture in China in the last century, and even now, has been banned from all purposes. The disposal of obsolete DDT pesticide has been an urgent task for the Chinese government. In order to evaluate the feasibility of co-processing DDT in the current new style dry-process rotary kiln with a precalciner as the feeding point, the destruction efficiency (DE) of DDTs (including p,p'-DDT, o,p'-DDT, p,p'-DDE and p,p'-DDD), proportion of DDTs in the combustion residue and exhaust gas, and the release of chlorine were studied under different operating conditions of temperature, oxygen content and gas retention time in the laboratory. The DE of DDTs exceeded 99% when the temperature was over 800 degrees C with enough oxygen. As the temperature increased from 600 degrees C to 1200 degrees C, the proportion of p,p'-DDD increased and p,p'-DDT decreased but still the main effective component remained in the combustion residue. In the exhaust gas, the most dominant phenomenon was the rapid increase in p,p'-DDE concentration as the temperature increased. The release of chlorine reached a peak between 800 degrees C and 900 degrees C. It was found that the oxygen content had a positive correlation with the process of dechlorination. The proportion of p,p'-DDE increased as the oxygen content was increased in the exhaust gas. The gas retention time had almost no influenced on the DE of DDTs, but affected the degradation extent of DDTs in the gas phase. These experiments showed that co-processing of obsolete DDT pesticide in cement kiln precalciners is feasible.
