A study of copper recovery from copper‐contaminated sludge with ferrite and selective leaching processes

Abstract

The purpose of this study was to develop an effective resource recovery and leached residue stabilization process for copper-contaminated sludge. To this end, a treatment procedure utilizing ferrite and selective leaching processes was developed. The XRD examination of ferrite complex revealed the crystalline phases to be mainly Fe 3 O 4 , CuO, and 6CuOÁCu 2 O.A selective leaching process was followed to recover the copper content of the ferrite complex. To promote the dissolution percentage of copper and repress that of iron, additional 0.5 N sulfuric acid was added at intervals to the suspension in the second step of the selective leaching process. The purpose of this operation was to return the suspension pH back to 3 to promote the dissolution of copper oxide and repress the dissolution of iron.Finally, the heavy metal (i.e., Cu, Pb, Cr, and Cd) dissolution of the above residue was examined with toxicity characteristic leaching procedure (TCLP) testing and all met the regulatory standard.

Recovery of Cu and Fe from Printed Circuit Board waste sludge by ultrasound: Evaluation of industrial application

“…For example, Hu et al [5] reported copper recovery from copper-contaminated sludge via utilizing ferrite and selective leaching processes. Kuchar et al [6] used a sulfidation treatment process for copper recovery from copper-containing plating sludge.…”

Characteristic improvement of metal‐contaminated sludge using mineralization technology

“…Since the particle size of hydroxide compounds is very tiny, polyvalent metal ions (i.e., Fe 21 , Fe 31 , Al 31 ) are utilized to form polynuclear-hydrolyzed complexes to promote the settling of the suspension. However, hydrated flocs usually have a high-specific surface area, resulting in water molecules being easily adsorbed on particle surfaces.…”

“…Owing to wastewater treatments in most plants relying on neutralization precipitation and coagulation, the resultant sludge is composed of metal hydroxides, which are precursors to ferrite formation in our mineralization treatment [21]. The crystalline structure of ferrite is the same as that of the cubic spinel (MgAl 2 O 4 ); however, the positions of Mg 21 and Al 31 are replaced easily by those of M 21 (bivalent metal ions) and Fe 31 . Copper sulfate and ferrous/ferric exist in wastewater systems because ferrous or ferric reagent is used for coagulation during wastewater treatment.…”

“…The filtration rate could be improved considerably when the crystalline characteristic of the residue is improved [19,20]. Owing to wastewater treatments in most plants relying on neutralization precipitation and coagulation, the resultant sludge is composed of metal hydroxides, which are precursors to ferrite formation in our mineralization treatment [21]. The crystalline structure of ferrite is the same as that of the cubic spinel (MgAl 2 O 4 ); however, the positions of Mg 21 and Al 31 are replaced easily by those of M 21 (bivalent metal ions) and Fe 31 .…”

“…During wastewater treatment by a ferrite process, Fe 21 and an alkaline agent are utilized to neutralize metal wastewater and produce a hydroxide mixture. After sedimentation, appropriate temperature and aeration are applied to transform the Fe(OH) 2 and Fe(OH) 3 into an intermediate complex hydro sol often referred to as green rust, which is followed by dehydration of the sol.…”