Recovery of nickel from Orimulsion fly ash by iminodiacetic acid chelating resin

Macroporous resins containing imminodiacetic acid (IDA) groups (Lewatit TP-207, Purolite S-930 and Amberlite IRC-748) were studied under dynamic conditions for uptake of nickel ions from the sulphate solution at pH 4 deriving from preliminary acid leaching of Orimulsion fly ash and subsequent vanadium recovery and impurities removal stages. The effects of temperature and ionic medium on the Ni adsorption were investigated.     

Comparative study of chelating ion exchange resins for the recovery of nickel and cobalt from laterite leach tailings

Commercially available chelating resins with the iminodiacetate functional group have been evaluated for their suitability for the adsorption of nickel and other metal ions by a resin-in-pulp process from the tailings of a pressure acid leach process for nickel laterites. The Amberlite IRC 748 and TP 207 MonoPlus resins were found to be the most suitable in terms of loading capacity for nickel and kinetics of adsorption. The resin with the highest nominal capacity was observed to adsorb less nickel as a result of the adsorption of greater amounts of the impurity ions. The equilibrium loading for nickel on the preferred resin was found to be similar from the ammonium and protonated form of the resin although the kinetics of adsorption is greater when the resin is initially in the ammonium form. A study of the kinetics of the loading of nickel and cobalt from pulp has shown that the rate can be described in terms of a first-order approach to equilibrium. The optimum pH for adsorption was found to be in the range 4 to 5 as this pH is high enough to maximize the adsorption of nickel and cobalt while preventing precipitation of nickel and cobalt as hydroxides from the pulp. A method for minimizing the competition from more strongly loaded ions such as iron(III) and chromium(III) which are present in the pulp was also developed in the initial laboratory phase of the study.     

Formation and recovery of Co,Ni, Cu macromolecular complexes with polystyrene and acrylic acid

The formation and structure of Co²⁺, Ni²⁺ and Cu²⁺ macromolecular complexes with a series of polystyrene and acrylic acid copolymers (PSt/AA) were studied. Both the copolymers and the metal complexes (M-PSt/AA) were characterized by FTIR, elemental analysis, Gel Permeation Chromatography and AAS. It is shown that the PSt/AA copolymer has rather strong coordination ability to the metal ions by chelation with the carboxylate group, and the microstructures of the M-PSt/AA complexes can be well controlled. Its adsorption behavior toward Co²⁺, Ni²⁺ or Cu²⁺ and various related parameters in the separation process were determined. The results indicate that the adsorption capability varies with pH and the maximum adsorption capacities were 337 mg/g for Co²⁺, 338 mg/g for Ni²⁺ and 341 mg/g for Cu²⁺ at around pH 7. Adsorption isotherms reveal that the adsorption process is consistent with the Freundlich equation. Experiments show that PSt/AA can recover Co²⁺, Ni²⁺ or Cu²⁺ with a high adsorption rate and high selectively coefficient from a simulated industry solution containing Ca²⁺ and Mg²⁺ as impurities. The resin can be readily stripped with acid and recycled for re-use after transformation to its sodium form.