| 摘要 |
A method for purifying sludge suspected of containing heavy, toxic and/or precious metals in order to extract them, the sludge being suspended in an aqueous solution and together forming a mass to be treated. FeCl<SUB>3 </SUB>is mixed with the mass, until an acidic pH of the solution is obtained. (CO<SUB>2</SUB>H)<SUB>2 </SUB>and NH<SUB>4</SUB>Cl are then mixed with the mass until metal pro-chelates are formed. Mixed alkali sulfides are then mixed with the mass until a solution with a very basic pH is obtained, to form colloidal complex iron chelates, which trap the metals. The solution is neutralized by adding an acid, until alkaline-ferrous sulfides and hydroxides containing the metals are precipitated. The mass is then centrifuged to form from the mass a liquid phase and a solid phase, the solid phase containing the alkaline-ferrous sulfides.
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