| 摘要 |
A method is provided for selectively treating flocculated heavy metal contaminated iron-based sludges from an industrial waste water treatment process. The method removes the heavy metal contaminants with a minimum loss of the iron therein. The method comprises dissolving the sludge in hydrochloric acid to produce a ferric chloride solution. The solution is filtered to remove precipitated heavy metal salts, such as lead chloride. The filtrate containing the remaining heavy metal chlorides and ferric chloride is then cooled or otherwise treated to remove additional heavy metal chlorides. The remaining ferric chloride based solution is then reduced (exposed to iron powder) to a ferrous chloride solution and heavy metals. After filtration of any additional precipitated heavy metals, the ferrous chloride solution is ready for recycling. The precipitated/filtered heavy metal salts can be supplied to one or more conventional recovery processes to produce one or more heavy metals, instead of disposing of them as hazardous waste.
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