| 摘要 |
PROBLEM TO BE SOLVED: To make it possible to accurately determine the adding amount of a pH adjusting agent beforehand depending on the pH of dust containing heavy metals and to render the dust harmless, in the treatment of the dust containing heavy metal for changing to ferrite. SOLUTION: When dust containing heavy metals is stored in a hopper with a scale 2 while weighing, a part of the dust is obtained and weighed, and an acid or an alkali is added to a pH adjusting and measuring tank 6 so that pH of the obtained ash may become 7-11, and the added amount is measured. The second process consists of the ratio of the weight of the dust (a) sampled in the tank 6; and the added amount of the acid or the alkali (b); and the adding amount (B)of the acid or the alkali required so that pH of the dust of the weight (A) fed to a mixing reactor 17 may be 7-11, will be determined from (a/b=A/B). The heavy metals in the dust is rendered harmless by adding the amount of the acid or the alkali (B) into the reactor 17.
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