| 摘要 |
<p>PROBLEM TO BE SOLVED: To provide a method for making molten fly ash generated in melting treatment of incineration ash harmless and recovering heavy metals, which is avoided in the use of the large quantity of chemicals and suppressed in the quantity of final waste. SOLUTION: This method comprises (A) a washing process for dissolving soluble components in water by dispersing the molten fly ash in water, (B) a precipitation process for precipitating calcium as a carbonate and dissolving the alkali metals and heavy metals as soluble compounds in the liquid by blowing a high concentration carbon dioxide-containing gas to decrease the pH of the liquid to 5.5-6.5, (C) a process for filtering and separating calcium carbonate generated in the precipitation process with other insoluble components, (D) a process for precipitating the heavy metals as the hydroxide while the compounds of the alkali metals is dissolved in the liquid by adding a water soluble alkaline material in the filtrate in the filtering process to increase pH 9-10 and (E) a process for filtering, separating and recovering the precipitate generated in the precipitation process.</p> |
