Treatment of Cr(VI) in COPR using ferrous sulfate–sulfuric acid or cationic polysulfides / James M. Tinjum in Journal of geotechnical and geoenvironmental engineering, Vol. 134 n°12 (Décembre 2008)  

Treatment of Cr(VI) in COPR using ferrous sulfate–sulfuric acid or cationic polysulfides [texte imprimé] / James M. Tinjum, Auteur ; Craig H. Benson, Auteur ; Tuncer B. Edil, Auteur . - 2009 . - pp. 1791–1803.
Geotechnical and geoenvironmental engineering
Langues : Anglais (eng)
in Journal of geotechnical and geoenvironmental engineering > Vol. 134 n°12 (Décembre 2008) . - pp. 1791–1803

Mots-clés :	Acids Chemical treatment Expansive soils Industrial wastes Metals Stabilization Sulfides
Résumé :	Column tests were conducted to evaluate two treatment strategies for reducing and stabilizing hexavalent chromium, Cr(VI), in chromium ore processing residue (COPR): permeation with a FeSO4–H2SO4 solution and blending with a cationic polysulfide reagent (CaSX) . Cr(VI) leached at concentrations exceeding 50mg∕L from untreated COPR permeated with synthetic groundwater for >20 pore volumes of flow (PVF), and concentrations of Cr(VI) in the solid phase remained high (6,600mg∕kg) . Permeation with solutions containing FeSO4–H2SO4 eliminated Cr(VI) from the effluent after initial, elevated leaching of Cr(VI) (100–1,500mg∕kg) ; however, high solid-phase concentrations of Cr(VI) remained in the column residuals (>1,300mg∕kg) . COPR treated with CaSX leached Cr at two orders of magnitude. However, acid dissolution channels eventually formed, resulting in preferential flow. COPR permeated with FeSO4–H2SO4 contained less brownmillerite and Cr(VI)-bearing hydrocalumite and hydrogarnet relative to untreated COPR. For COPR treated with CaSx , S encapsulated the subparticles of COPR with some micropore penetration, suggesting permanence of excess reductant after leaching with 23.5 PVF of synthetic rainwater.
En ligne :	http://ascelibrary.org/doi/abs/10.1061/%28ASCE%291090-0241%282008%29134%3A12%281 [...]