Evaluation of dioxins and dioxin-like compounds from a cement plant using carbide slag from chlor-alkali industry as the major raw material

• Published in: Journal of hazardous materials Vol. 330; pp. 135 - 141
• Main Authors: Zhao, Yuyang, Zhan, Jiayu, Liu, Guorui, Zheng, Minghui, Jin, Rong, Yang, Lili, Hao, Liwei, Wu, Xiaolin, Zhang, Xian, Wang, Pu
• Format: Journal Article
• Language: English
• Published: Netherlands Elsevier B.V 15.05.2017
• Subjects: Carbide slag; Cement; Dioxin; Polychlorinated biphenyl; Polychlorinated naphthalene; Carbide slag; Polychlorinated naphthalene; Polychlorinated biphenyl; Dioxin; Cement
• ISSN: 0304-3894; 1873-3336
• DOI: 10.1016/j.jhazmat.2017.02.018

•POP profiles from a cement kiln using carbide slag as raw material were studied.•PCN emissions were higher than those of PCDD/Fs and PCBs.•Mass balance showed that TEQs of all POPs were reduced by this kiln system.•PCN emissions from the investigated system should be emphasized. Carbide slag produced from chlor-alkali industry contains high amounts of calcium compounds and can potentially be used as raw material for cement production; however, it contains large amounts of chlorine so it is essential to evaluate the emissions of chlorinated organic pollutants, including polychlorinated dibenzo-p-dioxins and dibenzofurans (PCDD/Fs), polychlorinated biphenyls (PCBs), and polychlorinated naphthalenes (PCNs). A field study of the emission profiles of these pollutants in a cement plant using such slag was performed. The average concentrations of PCDD/Fs, PCBs, and PCNs in stack gases collected at the kiln back end were 6.31, 1.07, and 31.89pg TEQ m−3, respectively. PCDFs dominated over PCDDs in particulate samples. Di- to pentachlorinated biphenyls were dominant homologs in the particulate samples. MonoCBs were the dominant homolog in stack gases from the kiln back end, and homolog concentrations decreased with increasing chlorine numbers. Mono- and diCNs accounted for 48–98% of PCNs. The estimated toxic equivalents of stack gas emissions of PCNs, classified as new persistent organic pollutants under Stockholm Convention, were unexpectedly higher than those of PCDD/Fs and PCBs. A mass balance indicated that all of the toxic equivalents were reduced by this cement kiln system. The highest 2,3,7,8-PCDD/F output is with clinker.