METHOD FOR TREATMENT OF FLY ASH INVOLVING FIXATION OF CARBON DIOXIDE

摘要

A method for the treatment of a fly ash involving the fixation of carbon dioxide, which comprises [1] a step (washing step) of washing a fly ash in a fluid having a pulp concentration of 5 to 100 g/L, while blowing a CO2 gas into the fluid, to thereby dissolve a Ca component as Ca(HCO3)2, and [2] a step of subjecting the slurry formed in the above washing step to a solid-liquid separation, to thereby recover Ca(HCO3)2 in a solution after washing and also recover a solid component as a washing residue. The above solution after washing can be used for producing CaCO3. On the other hand, the above washing residue has a low Ca content, which results in the by-production of a Pb-containing residue having a low content of gypsum through subjecting the washing residue to the leaching with sulfuric acid, and the Pb-containing residue is useful in Pb refining. Further, the solution after the separation of the Pb-containing residue can be used as a raw material for Zn refining.