Specialized metallurgical processes – compositions for use therei – Processes – Free metal or alloy reductant contains magnesium
Patent
1994-11-17
1995-11-21
Rosenberg, Peter D.
Specialized metallurgical processes, compositions for use therei
Processes
Free metal or alloy reductant contains magnesium
423139, 423140, C22B 314, C22B 344, C01G 5100
Patent
active
054682819
DESCRIPTION:
BRIEF SUMMARY
FIELD OF THE INVENTION
This invention relates to a process for the recovery of cobalt from an aqueous solution containing nickel and cobalt and, more particularly, relates to the separation of cobalt from nickel dissolved in an ammoniacal leach liquor to produce a substantially nickel-free cobalt solution from which high purity cobalt metal and salt products can be obtained.
BACKGROUND OF THE INVENTION
A hydrometallurgical process for the treatment of nickel-cobalt-copper sulphide concentrates and mattes to produce high grade nickel and cobalt powders has been in commercial operation for many years. In this process which is described in the publication, "The Winning of Nickel". J. R. Boldt, Jr. (Ed), Toronto, Longmarts Canada Limited, 1967, pages 299 to 314, the nickel sulphide feed materials are leached in ammoniacal ammonium sulphate solution, under elevated air pressure, in horizontal autoclaves. The metals: nickel, cobalt and copper, are dissolved as metal amine complex ions. Iron is oxidized to insoluble hematite, and sulphide sulphur is partially oxidized to form a range of unsaturated sulphur anions which remain in the leach solution. The hematite residue is filtered off and discarded, and the leach solution is treated to remove copper, to partially remove the ammonia, and to oxidize the sulphur anions to sulphate. The purified solution, which contains about 60 g/L Ni and 1 g/L Co, is then treated with hydrogen under elevated pressure and temperature to precipitate nickel selectively as the metal powder. The cobalt remains in the reduced solution which contains about 1 g/L Ni and 1 g/L Co. The residual metals are then precipitated using hydrogen sulphide to produce a mixed nickel cobalt sulphide which forms the feed to the cobalt refining process.
The recovery of cobalt, in this nickel refining process, is much lower than that of nickel, as a result of the adsorption of cobalt by the iron oxide leach residue. Furthermore, the selectivity of the reduction process, for nickel, depends on the maintenance of a low level of cobalt in the purified leach solution. It is only possible to produce nickel powder meeting the market specifications for cobalt, if the Ni:Co ratio is maintained above about 20:1. It will be appreciated therefore that this nickel refining process is not economically effective for the treatment of nickel feed materials with high cobalt content, since significant losses of cobalt to the leach residue and to the nickel powder product will be incurred.
A commercial cobalt refining process based on the soluble cobaltic pentammine process for separating nickel from cobalt, is operated in conjunction with the above nickel refining process. This process is based on U.S. Pat. Nos. 2,694,005, 2,694,006, 2,767,054 and 2,767,055 to Schaufelburger. In the refining process, mixed nickel-cobalt sulphides with a typical Ni:Co ratio of 1:1, are first leached at elevated air pressure and temperature in dilute sulphuric acid solution to dissolve the nickel and cobalt and oxidize the sulphide to sulphate. The acidic leach solution, containing cobalt and nickel sulphates, is purified to remove iron and trace metals such as Cu, Cd and Zn. Ammonia is then added to neutralize the free acid and to adjust the ammonia to metals mole ratio to form the-pentammine ions of divalent nickel and cobalt. The solution is then treated with air under pressure in an autoclave, to oxidize the cobalt (II) pentammine ion to the cobalt (III) pentammine ion. The nickel (II) pentammine ion is not oxidized under these conditions. The oxidized solution is then treated in a two-stage process with concentrated sulphuric acid to selectively precipitate nickel as the nickel ammonium sulphate double salt (NiSO.sub.4. (NH.sub.4)SO.sub.4), leaving cobalt (III) pentammine sulphate in solution. After the second stage of nickel removal, the cobaltic solution is essentially nickel-free, with a Co:Ni ratio greater than 1000:1. The cobalt (III) ion is reduced to cobalt (II), and acid is added to adjust the NH.sub.3 :Co mole ratio to about
REFERENCES:
patent: 2694005 (1954-11-01), Schaufelberger
patent: 2694006 (1954-11-01), Schaufelberger
patent: 2767054 (1956-10-01), Schaufelberger
patent: 2767055 (1956-10-01), Schaufelberger
patent: 2822264 (1958-02-01), Benoit
patent: 3227513 (1966-01-01), Alexa et al.
patent: 3751558 (1973-08-01), Crnojevich et al.
patent: 3933975 (1976-01-01), Nikolic et al.
patent: 4394357 (1983-07-01), Mounsey
patent: 4563213 (1986-01-01), Hubred
patent: 4600435 (1986-07-01), Wiegers
patent: 4619816 (1986-10-01), Ricketton
patent: 5102633 (1992-04-01), Husted
patent: 5174812 (1992-12-01), Price
Chemical Abstracts, vol. 77, No. 16, Oct. 16, 1972, Columbus, Ohio Abstract 104224p p. 155.
Chemical Abstracts, vol. 85, No. 24, Dec. 13, 1976, Columbus, Ohio Abstract No. 190652a, p. 193.
Chemical Engineering, Sep. 7, 1959, p. 145.
The Winning of Nickel--J. R. Boldt J., Edmonton, Alberta pp. 299-314.
Fors Arne I.
Horne D. Doak
Imai Jeffrey T.
Rosenberg Peter D.
Sherritt Gordon Limited
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