State and leaching characteristics of Cr and As in the solid phase products of ultra-low emission coal-fired units

The content and state and leaching characteristics of the two trace elements, viz., chromium (Cr) and arsenic (As), in the solid product of ultra-low emission units in the coal-fired power plants are investigated. The results show that the contents of chromium and arsenic in the fly ash are in general higher than those in the bottom slag. In the fly ash samples of units 1#, 2#, and 3#, the most abundant chromium and arsenic species appear in the exchangeable state and oxidizable state, respectively, whereas in the ash sample of unit 4#, the residues account for the most chromium and arsenic species. The leaching concentration of arsenic is lower than 0.01 mg/L as specified in the groundwater environmental standard (GB 14848—2017); however, the leaching concentration of chromium in the fly ash of 2# and 3# units is higher than the emission limit, to which close attention should be paid.