title: Recovery of molybdenum, nickel and cobalt by precipitation from the acidic leachate of a mineral sludge.
abstract: The objective of this study was to investigate the recovery potential of molybdenum (Mo), nickel (Ni) and cobalt (Co) from synthetic and real acidic leachate of a mineral sludge from a metal recycling plant by sulfide precipitation. The operational parameters (metal sulfide (M/S) ratio 0.1-1, agitation speed 0-100 rpm, contact time 15-120 min and pH 1-5) were optimized in batch conditions on synthetic metal leachate (0.5 M HNO3, Mo = 101.6 mg L(-1), Ni = 70.8 mg L(-1), Co = 27.1 mg L(-1)) with a 0.1 M Na2S solution. Additionally, recovery of the target metals was theoretically simulated with a chemical equilibrium model (Visual MINTEQ 3.0). The optimized Na2S precipitation of metals from the synthetic leachate resulted in the potential selective recovery of Mo at pH 1 (98% by modeling, 95% experimental), after simultaneous precipitation of Ni and Co as sulfide at pH 4 (100% by modeling, 98% experimental). Metal precipitation from the real leachate (18 M H2SO4, Mo = 10,160 mg L(-1), Ni = 7,080 mg L(-1), Co = 2,710 mg L(-1)) was performed with 1 M Na2S, and resulted in a maximal Mo recovery at pH 2 (50%), while maximal recoveries of Ni and Co were observed at pH 4 (56% and 60%, respectively). Real leachate gave a lower metals recovery efficiency compared with synthetic leachate, which can be attributed to changes in the pH, nature of leachant, co-precipitation of Zn and competition for S(2-) ions.
authors.affiliation: a Laboratoire Géomatériaux et Environnement (LGE), Université Paris-Est , Marne-la-Vallée , France.|b Groupement de Recherche Eau-Sol-Environnement (GRESE), Université de Limoges, Faculté des Sciences & Techniques , Limoges , France.|d UNESCO-IHE Institute for Water Education , AX Delft , The Netherlands.
authors.forename: M
authors.initials: M
authors.lastname: Vemic
authors.affiliation: b Groupement de Recherche Eau-Sol-Environnement (GRESE), Université de Limoges, Faculté des Sciences & Techniques , Limoges , France.
authors.forename: F
authors.initials: F
authors.lastname: Bordas
authors.affiliation: c ERAMET , Le Palais sur Vienne , France.
authors.forename: S
authors.initials: S
authors.lastname: Comte
authors.affiliation: b Groupement de Recherche Eau-Sol-Environnement (GRESE), Université de Limoges, Faculté des Sciences & Techniques , Limoges , France.
authors.forename: G
authors.initials: G
authors.lastname: Guibaud
authors.affiliation: d UNESCO-IHE Institute for Water Education , AX Delft , The Netherlands.
authors.forename: P N L
authors.initials: PN
authors.lastname: Lens
authors.affiliation: a Laboratoire Géomatériaux et Environnement (LGE), Université Paris-Est , Marne-la-Vallée , France.
authors.forename: E D
authors.initials: ED
authors.lastname: van Hullebusch
mesh_terms: D011232:Chemical Precipitation; D007220:Industrial Waste; D019216:Metals, Heavy / Q000032:analysis / Q000737:chemistry* / Q000302:isolation & purification*; D059027:Recycling / Q000379:methods*; D012722:Sewage / Q000737:chemistry*
chemical_list: D007220:Industrial Waste; D019216:Metals, Heavy; D012722:Sewage
keywords: Molybdenum; cobalt; nickel; recovery; sulfide precipitation