Characteristics of dioxin emissions from a Waelz plant with acid and basic kiln mode

Pao Chen Hung, Kai Hsien Chi, Mei Lien Chen, Moo Been Chang

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10 Scopus citations

Abstract

The concentrations of polychlorinated dibenzo-p-dioxins and dibenzofurans (PCDD/Fs) were measured in the flue gas of a Waelz plant operated in acid and basic modes, respectively. To abate (PCDD/F) and other pollutants, the plant operates with a post-treatment of flue gases by activated carbon injection and subsequent filtration. Relatively high PCDD/F discharge by fly ashes is found with acid kiln mode of the Waelz process. Therefore, basic kiln mode of the Waelz process is investigated and compared in this plant. With the adsorbent injection rate of 7kg/h (95mg/Nm 3), the PCDD/F concentration in stack gas was measured as 0.123ng I-TEQ/Nm 3 in the basic operating mode. The added Ca(OH) 2 reacted with metal catalysts and HCl (g) in the flue gas and thus effectively suppressed the formation of PCDD/Fs. PCDD/F concentrations in fly ashes sampled from the dust settling chamber, cyclone, primary filter and secondary filter in basic kiln mode were significantly lower than that in acid kiln mode. Total PCDD/F emission on the basis of treating one kg of electric arc furnace dust in the basic operation mode was 269ng I-TEQ/kg EAF-dust treated which was significantly lower than that in acid mode (640ng I-TEQ/kg EAF-dust treated).

Original languageEnglish
Pages (from-to)229-235
Number of pages7
JournalJournal of Hazardous Materials
Volume201-202
DOIs
StatePublished - 30 Jan 2012

Keywords

  • Basic kiln mode
  • Metal recovery
  • Partitioning
  • PCDD/F
  • Waelz process

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