| abstract |
[Problem] To prevent the elution of heavy metals, which can reduce the elution of lead when spraying a carbonate-containing alkali metal compound such as sodium hydrogen carbonate to combustion exhaust gas, compared to the case where phosphoric acid is added alone to the fly ash. Provide a method. A carbonate-containing alkali metal compound is added to combustion exhaust gas by spraying. While adding a calcium compound to the fly ash, the pH of the eluate shown in the Environmental Agency Notification No. 13 test (L / S = 10) is adjusted to 8 to 11, and the calcium ion concentration in the eluate is 50 mg / Adjust to L or more. Specific examples of calcium compounds include slaked lime, calcium chloride, quicklime, calcium nitrate, calcium nitrite, calcium silicon, calcium acetate, and calcium organic acid salts. Among them, slaked lime and calcium chloride are preferable because of good solubility of calcium. [Selection figure] None |