Removal of total chromium from chromium slag leachate by fly ash combined with calcium oxide

Fly ash has a large specific surface area, but as a treatment agent used alone in chromium containing wastewater was not efficient for its low adsorption capacity, high dissolution loss and leaching toxicity. In order to solve the above defects, the technology of fly ash combined with calcium oxide was used to remove the total chromium from chromium slag leachate. It could be concluded that when temperature was 25℃, the weight ratio of fly ash to calcium was 1:1, the initial concentration of total chromium was in the range of 0.30-80.00 mg/L, the rotation speed was 150 r/min, the total chromium removal rate could reach more than 90%. The control sample research showed that using fly ash combined with calcium oxide was better than the using fly ash or calcium oxide alone as adsorbent for the total chromium treatment. Using SEM, XRD and Infrared spectrum to characterize the raw material of fly ash, the treated chromium residue and so on, the results showed that the reaction with fly ash and calcium oxide could generate crystal mineral in the medium of water, in which process chromium could be included in the crystal mineral. The leaching test of residue showed that the chromium was fixed very well in crystal mineral.