The processing methodological null zinc of the flying ash which contains the heavy metal

摘要

PROBLEM TO BE SOLVED: To provide a method in which useful heavy metals in fly ash are separated from chlorine and salts of calcium, and the like, and separated/recovered in a recyclable form in a smelting process, especially selenium in drainage is treated together with other heavy metals at room temperature, and the concentration of selenium is decreased to a drainage standard value or below. ;SOLUTION: A treatment method includes a salt elution process in which fly ash is added with a mineral acid to be converted into slurry, a heavy metal separation process in which the slurry is neutralized to be separated into precipitates containing heavy metals and filtrate containing salts, a dissolved oxygen removing process for removing dissolved oxygen from the filtrate, an iron salt coprecipitation process in which an iron (II) salt is added to adjust pH at 8-11, preferably at 8-9 and 9-11 in turn in two stages, to coprecipitate seleniun and other heavy metals with iron hydroxide, a precipitate washing process for washing the heavy metal-containing precipitates, and a heavy metal recovery process in which the washed precipitates, after being repulped with a mineral acid, is neutralized again for solid-liquid separation. The filtrate in the heavy metal recovery process is used as water to make the slurry in the salt elution process.;COPYRIGHT: (C)2001,JPO