Distribution of Hg, As and Se in material and flue gas streams from preheater-precalciner cement kilns and vertical shaft cement kilns in China

作者：Yan Dahai; Peng Zheng^*; Ding Qiong; Karstensen Kare Helge; Engelsen Christian J; Li Li; Ren Yong; Jiang Chen

来源：Journal of the Air and Waste Management Association, 2015, 65(8): 1002-1010.

DOI：10.1080/10962247.2015.1051607

The aim of this study was to evaluate the behavior of Hg, As, and Se in cement production. Two types of cement plants were studied, including the vertical shaft kiln (VSK) and preheater-precalciner kiln (PPK) processes. Determination of Hg, As, and Se in the main material and gas streams were performed. It was found that recycling of particulate matter captured by an air pollution control device caused a significant enrichment of Hg and As inside both processes. The total quantity of Hg entering the process and the quantity emitted to the atmosphere were found to be 10-109 and 6.3-38 mg, respectively, per ton of clinker produced. The average Hg emission was calculated to be around 41% of the total mercury input. The emissions found complied with the European Union (EU) limit and exceeded partly the U.S. limit. Furthermore, it was found that oxidized mercury was the dominant species in the PPK process, whereas the reduced form was dominant in the VSK process, due to the oxidizing and reducing gas conditions, respectively. Regarding the distribution of As and Se, the major amounts were bound to the solid materials, that is, cement clinker and particulate matter. Based on cement production data in China in 2013, the annual emissions of Hg and As were estimated to be in the range of 8.6-52 and 4.1-9.5 tons, respectively.Implications: There are fairly limited studies on Hg, As, and Se measurements from cement manufacturing facilities in China, and even more limited studies on the behavior in vertical shaft kilns. The needs for increased emission reduction efforts in energy-intensive industries are globally recognized, and an improved understanding of the processes ongoing in a cement kilns system is decisive. Since the processes are complex and almost impossible to recreate in the laboratory, field measurements are indeed important. The findings in the present study were solely based on field measurements and the data are considered to be valuable for the further development of emission reduction technology.

• 出版日期2015-8
• 单位中国环境科学研究院