Nickel, separation from cobalt

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. 

A mineral ore contains cobalt and small amounts of nickel. In order to determine the nickel concentration it must be separated from cobalt. Solvent extraction using 0.01 M 8-hydroxyquinoline in CHCI3 is chosen. Which metal should be extracted from the other, and at what pH Consider Figure 9.3 and connected text. 

Pavlides, A. G. and Wyethe, J. 2000. Ion exchange column design for separation of nickel traces from cobalt electrolyte. In Proceedings ALTA SX/IX-1. Melbourne ALTA Metallurgical Services. 

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). 

Gas Reduction. The use of a gaseous reduciag agent is attractive because the metal is produced as a powder that can easily be separated from the solution. Carbon dioxide, sulfur dioxide, and hydrogen can be used to precipitate copper, nickel, and cobalt, but only hydrogen reduction is appHed on an iadustrial scale. In the Sherritt-Gordon process, the excess ammonia is removed duting the purification to achieve a 2 1 ratio of NH iNi ia solution. Nickel powder is then precipitated by... 

The mixture can be separated by distillation. The primary phosphine is recycled for use ia the subsequent autoclave batch, the secondary phosphine is further derivatized to the corresponding phosphinic acid which is widely employed ia the iadustry for the separation of cobalt from nickel by solvent extraction. With even more hindered olefins, such as cyclohexene [110-83-8] the formation of tertiary phosphines is almost nondetectable. 

Solvent Extraction Reagents. Solvent extraction is a solution purification process that is used extensively in the metallurgical and chemical industries. Both inorganic (34,35) and organic (36) solutes are recovered. The large commercial uses of phosphine derivatives in this area involve the separation of cobalt [7440-48-4] from nickel [7440-02-0] and the recovery of acetic acid [61-19-7] and uranium [7440-61-1]. 

Assay of beryUium metal and beryUium compounds is usuaUy accompHshed by titration. The sample is dissolved in sulfuric acid. Solution pH is adjusted to 8.5 using sodium hydroxide. The beryUium hydroxide precipitate is redissolved by addition of excess sodium fluoride. Liberated hydroxide is titrated with sulfuric acid. The beryUium content of the sample is calculated from the titration volume. Standards containing known beryUium concentrations must be analyzed along with the samples, as complexation of beryUium by fluoride is not quantitative. Titration rate and hold times ate critical therefore use of an automatic titrator is recommended. Other fluotide-complexing elements such as aluminum, sUicon, zirconium, hafnium, uranium, thorium, and rate earth elements must be absent, or must be corrected for if present in smaU amounts. Copper-beryUium and nickel—beryUium aUoys can be analyzed by titration if the beryUium is first separated from copper, nickel, and cobalt by ammonium hydroxide precipitation (15,16). 

D. Benzoin-a-oxime (cupron) (VII). This compound yields a green predpitate, CuC14Hu02N, with copper in dilute ammoniacal solution, which may be dried to constant weight at 100 °C. Ions which are predpitated by aqueous ammonia are kept in solution by the addition of tartrate the reagent is then spedfic for copper. Copper may thus be separated from cadmium, lead, nickel, cobalt, zinc, aluminium, and small amounts of iron. 

Determination of titanium with tannic acid and phenazone Discussion. This method affords a separation from iron, aluminium, chromium, manganese, nickel, cobalt, and zinc, and is applicable in the presence of phosphates and silicates. Small quantities of titanium (2-50 mg) may be readily determined. 

Determination of tungsten as the trioxide (tannic acid-phenazone method) Discussion. Tungstic acid is incompletely precipitated from solutions of tungstates by tannic acid. If, however, phenazone (2,3-dimethyl-l-phenyl-5-pyrazolone) is added to the cold solution after treatment with excess of tannic acid, precipitation is quantitative. This process effects a separation from aluminium, and also from iron, chromium, manganese, zinc, cobalt, and nickel if a double precipitation is used. 

The aforementioned fact is also the basis for the separation of co-occurring metals from each other. Whenever feasible, such electrochemical separation is an interesting and effective technique, in principle. In practice, however, such selective deposition is not considered very feasible, particularly for elements which are close neighbors in the electrochemical series. For example, the decomposition potentials of nickel and of cobalt are -0.25 V and -0.27 V, respectively. This small 0.02 V difference makes the selective deposition of nickel, leaving cobalt in the solution, or vice versa, rather difficult to achieve in practice. On the other hand, it is quite easy to co-deposit nickel and cobalt and to obtain an alloy. 

Arsenic and lead are conveniently co-precipitated and removed with the cobalt precipitate. Finally, copper is separated from solution as copper(II) sulfide by stirring in nickel powder and elemental sulfur... 

Sarangi, K. Reddy, B. R. Das, R. P. Extraction studies of cobalt (II) and nickel (II) from chloride solutions using Na-cyanex 272. Separation of Co(II)/Ni(II) by the sodium salts of D2EHPA, PC88A and Cyanex 272 and their mixtures. Hydrometallurgy 1999, 52, 253-265. 

Liranza, E. G. Daudinot, A. M. Martinez, R. V. Barzaga, B. R. Separation of cobalt and nickel by solvent extraction from sulfate liquors obtained by acid leaching of a product from the caron process. International Solvent Extraction Conference, Cape Town, South Africa, Mar. 17-21, 2002, 952-957. 

Feather, A. M. Cole, P. M. The separation of cobalt from nickel ammonium sulfate solution by solvent extraction. Value Adding through Solvent Extraction, [Papers presented at ISEC 96], Melbourne, Mar. 19-23, 1996, 1, 511-516. 

Gandhi, M. N. Deorkar, N. V. Khopkar, S. M. Solvent extraction separation of cobalt(II) from nickel and other metals with Cyanex-272. Talanta 1993, 40, 1535-1539. 

In another procedure [522] the sample of seawater (0.5-3 litres) is filtered through a membrane-filter (pore size 0.7 xm) which is then wet-ashed. The nickel is separated from the resulting solution by extraction as the dimethylglyoxime complex and is then determined by its catalysis of the reaction of Tiron and diphenylcarbazone with hydrogen peroxide, with spectrophotometric measurement at 413 nm. Cobalt is first separated as the 2-nitroso-1-naphthol complex, and is determined by its catalysis of the oxidation of alizarin by hydrogen peroxide at pH 12.4. Sensitivities are 0.8 xg/l (nickel) and 0.04 xg/l (cobalt). 

Berndt et al. [740] have shown that traces of bismuth, cadmium, copper, cobalt, indium, nickel, lead, thallium, and zinc could be separated from samples of seawater, mineral water, and drinking water by complexation with the ammonium salt of pyrrolidine- 1-dithiocarboxylic acid, followed by filtration through a filter covered with a layer of active carbon. Sample volumes could range from 100 ml to 10 litres. The elements were dissolved in nitric acid and then determined by atomic absorption or inductively coupled plasma optical emission spectrometry. 

Low-molecular-weight extractants can generally be expected to have uneconomic solubilities in most systems, but where high salt concentrations prevail, the solubility may be substantially lower and may be economic. This has been shown to be true for naphthenic and Versatic acids, which have high solubilities in water but appear to be economically useful when used in high ammonium sulfate liquors, such as those produced in the Sherritt-Gordon process for the extraction of cobalt and separation from nickel [12]. 

The solubility of Versatic 911 in water has been studied as a function of both pH and salt concentration for a fixed (0.5 mol dm ) concentration of reagent in the solvent [15] and is illustrated in Fig. 7.10. The use of high salt concentrations (4moldm ammonium sulfate) has been shown to be effective in keeping Versatic 911 losses at pH 7-8 to more economic levels (<100 ppm) in the separation of cobalt from nickel [16]. 

Ritcey, G. M. Ashbrook, A. W. Lucas, B. H. Development of a solvent extraction process for the separation of cobalt from nickel, presented at the Annual AIME Meeting, San Francisco, 1972. CIM Bull., January 1975. 

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... 

Nickel may he measured quantitatively hy several microanalytical gravimetric methods that include (l)formation of a red precipitate with dimethyl-glyoxime, (2) precipitation as a hlack sulfide with ammonium sulfide, (3) precipitating as a complex cyanide hy treating with alkali cyanide and bromine, and (4) precipitation as a yellow complex hy treating an ammoniacal solution of nickel with dicyandiamide sulfate (Grossman s reagent), followed hy the addition of potassium hydroxide. All of these methods can separate nickel from cobalt in solution. 

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