CKD의 간접탄산화에 의한 이산화탄소 저장기술 연구

Abstract

In this study, we have developed an efficient indirect carbonation technique which stores carbon dioxide by making it react with cement kiln dust (CKD) involving Ca. Since it contains considerable amount of CaO (43%) and its particles are very fine (23.08μm), CKD is a very suitable industrial waste for mineral carbonation. Through Ca extraction experiment, at first, we have determined the optimal conditions for the type and concentration of Ca extractant, the extraction time, and the mixing ratio of CKD and extractant. Results show that the most efficient extractant includes hydrochloric acid, acetic acid, ammonium chloride, and ammonium acetate. The best extraction performance occurs at 1.74M (10%) of extractant concentration and at 30 min of extraction time. As well, the most economical mixing ratio of CKD and extractant is 1:10 (g/mL). However, the temperature and stirring speed hardly affect the efficiency of Ca extraction. To summarize, over 87% of Ca could be extracted from CKD under the optimal conditions. In the subsequent experiment of carbonation between Ca extract and carbon dioxide, it is found that high efficiency of carbonation is obtained up to 89.2%. As well, high purity of CaCO3 is produced by ammonium chloride and ammonium acetate, whereas no solid is formed by hydrochloric acid and acetic acid. We conclude that up to 318 kg of carbon dioxide could be stored by 1 ton of CKD through the carbonation at 25℃ after extracting Ca by ammonium acetate. It is expected that this study would be helpful to resolve global warming issues and make many contributions to reuse of CaCO3, cost reduction of CKD disposal, and environment-friendly treatment of CKD.