| 摘要 |
PURPOSE:To certainly prevent the elution of heavy metal from treated matter by easily, efficiently and safely treating soot. CONSTITUTION:Phosphoric acid and/or phosphate and silicic acid and/or silicate are added to soot to be kneaded therewith. Since a substance generating harmful gas is not contained in a chemical agent to be used, there is no possibility of the generation of harmful gas at the time of the addition of the chemical agent. Silicic acid and silicate form a compd. extremely low in solubulity along with heavy metal in an especially high pH region while phosphoric acid and phosphate form the above mentioned compd. along with heavy metal in an especially low pH region. By together using both chemical agents, the elution of heavy metal can be certainly prevented over a wide pH range. |
