Ceramics-Silikáty 46, (2) 52 - 55 (2002) |
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REPROCESSING OF ZINC GALVANIC WASTE SLUDGE BY SELECTIVE PRECIPITATION
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Jandová Jitka 1, Maixner Jaroslav 2, Grygar Tomáš 3
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1 Department of Metals and Corrosion Engineering, Institute of Chemical Technology, Prague
Technická 5, 166 28 Prague, Czech Republic
2 Central Laboratories, Institute of Chemical Technology, Prague
Technická 5, 166 28 Prague, Czech Republic
3
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Keywords: Galvanic sludge, Recovery, Zinc
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Multi-step selective precipitation method was tested for processing zinc waste galvanic sludge. This method involved acid leaching
of sludge in sulphuric acid, purification of sulphate leach liquors using a sequence of hydroxide, sulphide, and fluoride precipitation
to remove trivalent metals, Cu, Cd, Ca, Mg, and Si, oxidative precipitation to remove Mn, and finally precipitation of
Zn as zinc carbonate. The solids were separated from leach liquors after each precipitation step, and their phase composition
was determined by X-ray powder diffraction and elemental composition by AAS. The flowsheet proposed yielded relatively pure
Zn-precipitate, suitable for possible production of raw materials for ceramic, metallurgical, or pigment industry, however, due
to incomplete leaching of the sludge and co-precipitation of Zn to hydroxides of trivalent metals and Cu, Cd-sulphides, the overall
recovery efficiency was only 63-65 %. |
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