Nickel separator

Nickel and Cobalt. Often present with copper in sulfuric acid leach Hquors are nickel [7440-02-0] and cobalt [7440-48-4]. Extraction using an organophosphoric acid such as D2EHPA at a moderate (3 to 4) pH can readily take out the nickel and cobalt together, leaving the copper in the aqueous phase, but the cobalt—nickel separation is more difficult (274). In the case of chloride leach Hquors, separation of cobalt from nickel is inherently simpler because cobalt, unlike nickel, has a strong tendency to form anionic chloro-complexes. Thus cobalt can be separated by amine extractants, provided the chloride content of the aqueous phase is carefully controUed. A successhil example of this approach is the Falcon-bridge process developed in Norway (274). 

In addition, solvent extraction is appHed to the processing of other metals for the nuclear industry and to the reprocessing of spent fuels (see Nuclearreactors). It is commercially used for the cobalt—nickel separation prior to electrowinning in chloride electrolyte. Both extraction columns and mixer-settlers are in use. 

Daudinot, A. M. Liranza, E. G. Cobalt-nickel separation by solvent extraction in Cuba. International Solvent Extraction Conference, Cape Town, South Africa, Mar. 17-21, 2002, 964-969. 

Tait, B. K. Cobalt Nickel Separation—the extraction of cobalt(II) and nickel(H) by Cyanex-301, Cyanex-302 and Cyanex-272. Hydrometallurgy 1993, 32, 365-372. 

Fig. 7.6 Cobalt-nickel separation as a function of number of contact stages concentration of cobalt and nickel 20gdm each in aqueous feed solution.

American Cyanamid Company, Technical data on cobalt-nickel separation using CYANEX 272 extractant, 1982. 

These general differences in chemical behavior have been exploited to provide the solvent extraction processes currently used or proposed for cobalt-nickel separation. All these processes remove cobalt from nickel... 

For simple acidic extractants, such as carboxylic or sulfonic acids, the similarity in formation constants does not produce cobalt-nickel separation factors (Sn° 2) sufficiently large for commercial operation (Fig. 11.4). Data for pH versus extraction for some chelating acid extractants does seem to offer the possibility of separation [e.g., for the hydroxyoxime Acorga P50, the pHso for nickel(II) is 3.5 and for cobalt(II) 5.0]. Normally, this pH difference would be suitable for a separation process, but this particular system has hidden complications. The rate of nickel extraction is very slow compared with cobalt and, in addition, although cobalt is initially extracted... 

Earlier it was noted that nickel and cobalt could be extracted by carboxylic and sulfonic acids, with nickel being extracted at the lower pH. However, with alkylphosphorus acids, a selectivity reversal is observed, with cobalt being favored under acid conditions. The cobalt-nickel separation factor has been shown to depend upon metal concentration, reagent structure, diluent, temperature, and the presence of a diluent modifier. Thus, with increasing cobalt concentration the color of the extractant phase changes... 

An alternative route to cobalt/nickel separation following ammonia leaching in the Caron process is to produce a mixed Co/Ni carbonate product. This can then be dissolved in sulfate media and processed using one of the acidic extractants described later [13]. 

With analytical methods such as x-ray fluorescence (XRF), proton-induced x-ray emission (PIXE), and instrumental neutron activation analysis (INAA), many metals can be simultaneously analyzed without destroying the sample matrix. Of these, XRF and PEXE have good sensitivity and are frequently used to analyze nickel in environmental samples containing low levels of nickel such as rain, snow, and air (Hansson et al. 1988 Landsberger et al. 1983 Schroeder et al. 1987 Wiersema et al. 1984). The Texas Air Control Board, which uses XRF in its network of air monitors, reported a mean minimum detectable value of 6 ng nickel/m (Wiersema et al. 1984). A detection limit of 30 ng/L was obtained using PIXE with a nonselective preconcentration step (Hansson et al. 1988). In these techniques, the sample (e.g., air particulates collected on a filter) is irradiated with a source of x-ray photons or protons. The excited atoms emit their own characteristic energy spectrum, which is detected with an x-ray detector and multichannel analyzer. INAA and neutron activation analysis (NAA) with prior nickel separation and concentration have poor sensitivity and are rarely used (Schroeder et al. 1987 Stoeppler 1984). 

Ribeiro CP, Costa AOS, Lopes IPB, Campos FF, Ferreira AA, and Salum A. Cobalt extraction and cobalt-nickel separation from a simulated industrial leaching liquor by liquid surfactant membranes using Cyanex 302 as carrier. J Membr Sci 2004 241 45-54. Frankenfeld JW, Cahn RP, and Li NN. Extraction of copper by liquid membranes. Sep Sci Technol 1981 16 385 102. 

Conventional production of vitamin K consists of four steps hydrogenation of 2-methylnaphthoquinone-l,4 to 2-methylnaphthohydroquinone-l,4 in a solvent in the presence of Raney nickel separation of the product from the catalyst by filtration evaporation of the solvent and boiling with acetic anhydride. Because the anhydride is highly corrosive, it tends to attack the nickel, and hence complete separation of the catalyst is necessary. On the other hand, use of a palladium alloy membrane reactor eliminates corrosion and makes it possible to complete the whole process in a single step (Gryaznov et al., 1986). The overall reaction is... 

Bis (2,4,4,-trimethylpentyl) phosphinic acid extraction agent, nickel separation from sulfate media... 

Recent research has also been focusing on electrochemical recovery of cobalt from spent Li-ion cathodes. Researchers in Italy (20) and Brazil (21) investigated the recycling of cobalt from the cathodic material of Li-ion spent batteries, where the final cobalt recovery step relied on electrochemical techniques. In one example, the cathodic material (also containing nickel) was dissolved in acid, cobalt and nickel separated by solvent extraction, and the cobalt electrowon at 250 A/M, pH 4.1 and 50°C. In the other example, cathodic LiCo02 was acid leached, and the metallic cobalt deposited directly on 430 steel. The deposit was then oxidized to C03O4 in air at 850°C. 

Re-leaching of mixed hydroxide intermediates in ammonia solutions is impeded if aluminum is present [29]. Cobalt - nickel separation using solvent extraction with Cyanex 272 as practiced at the Bulong operation from 1999 to 2003, requires low levels of aluminum to avoid crud formation [30]. Aluminum can also adversely affect the performance of the Cyanex 301 reagent, as used at Goro for extraction of nickel and cobalt [31, 32]. 

The processing of the NorthMet deposit of PolyMet Mining using a combination of flotation and hydrometallurgical unit operations has been presented. The development of a split-cleaner flotation circuit followed by a copper-nickel separation process allows for generation of up to four concentrate products ... 

Flett, Douglas S. (2004) Cobalt-Nickel Separation in Hydrometallurgy a Review Chemistry for Sustainable Development 12 81-91... 

Advantages of the vapor-phase carbonylation using active carbon support in comparison with the liquid homogeneous catalyst system are as follows. Corrosive attack to reactors and pipes of iodide-acetic acid solution can be avoided. No problem of limited supply, such as of rhodium, is associated with use of nickel. Separation of products from catalyst is facilitated by a gas-solid system. These catalysts can work at higher temperature. 

Uranium extraction Rare earth extraction Cobalt/nickel separation Zinc extraction, etc. 

Cobalt/nickel separation Rare earth separation... 

Cobalt/nickel separation Zinc and iron extraction Magnesium extraction... 

Rickelton, W. A., Robertson, A. J., and Hillhouse, J. H. 1991. The significance of diluent oxidation in cobalt-nickel separation. Solvent Extr. Ion Exch. 9 73-84. 

This chapter is concerned with the study of kinetics of solute transfer at free liquid/liquid boundaries. This process has found many applications in separation science [1] with developments in hydrornetallurgy (e.g. Cobalt/Nickel separation), nuclear fuel reprocessing, pharmaceutical industry and supported liquid membrane technology. indexTransfer kinetics... 

Acidic carboxylic acids naphthenic acids Shell Chemical Co. copper-nickel separation... 

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